Solder fatigue

Solder fatigue is the mechanical degradation of solder due to deformation under cyclic loading. This can often occur at stress levels below the yield stress of solder as a result of repeated temperature fluctuations, mechanical vibrations, or mechanical loads. Techniques to evaluate solder fatigue behavior include finite element analysis and semi-analytical closed-form equations.
Overview.
Solder is a metal alloy used to form electrical, thermal, and mechanical interconnections between the component and printed circuit board (PCB) substrate in an electronic assembly. Although other forms of cyclic loading are known to cause solder fatigue, it has been estimated that the largest portion of electronic failures are thermomechanically driven due to temperature cycling. Under thermal cycling, stresses are generated in the solder due to coefficient of thermal expansion (CTE) mismatches. This causes the solder joints to experience non-recoverable deformation via creep and plasticity that accumulates and leads to degradation and eventual fracture.
Historically, tin-lead solders were common alloys used in the electronics industry. Although they are still used in select industries and applications, lead-free solders have become significantly more popular due to RoHS regulatory requirements. This new trend increased the need to understand the behavior of lead-free solders.
Much work has been done to characterize the creep-fatigue behavior of various solder alloys and develop predictive life damage models using a Physics of Failure approach. These models are often used when trying to assess solder joint reliability. The fatigue life of a solder joint depends on several factors including: the alloy type and resulting microstructure, the joint geometry, the component material properties, the PCB substrate material properties, the loading conditions, and the boundary conditions of the assembly.
Thermomechanical solder fatigue.
During a product's operational lifetime it undergoes temperature fluctuations from application specific temperature excursions and self-heating due to component power dissipation. Global and local mismatches of coefficient of thermal expansion (CTE) between the component, component leads, PCB substrate, and system level effects drive stresses in the interconnects (i.e. solder joints). Repeated temperature cycling eventually leads to thermomechanical fatigue.
The deformation characteristics of various solder alloys can be described at the microscale due to the differences in composition and resulting microstructure. Compositional differences lead to variations in phase(s), grain size, and intermetallics. This affects susceptibility to deformation mechanisms such as dislocation motion, diffusion, and grain boundary sliding. During thermal cycling, the solder's microstructure (grains/phases) will tend to coarsen as energy is dissipated from the joint. This eventually leads to crack initiation and propagation which can be described as accumulated fatigue damage.
The resulting bulk behavior of solder is described as viscoplastic (i.e. rate dependent inelastic deformation) with sensitivity to elevated temperatures. Most solders experience temperature exposures near their melting temperature (high homologous temperature) throughout their operational lifetime which makes them susceptible to significant creep. Several constitutive models have been developed to capture the creep characteristics of lead and lead-free solders. Creep behavior can be described in three stages: primary, secondary, and tertiary creep. When modeling solder, secondary creep, also called steady state creep (constant strain rate), is often the region of interest for describing solder behavior in electronics. Some models also incorporate primary creep. Two of the most popular models are hyperbolic sine models developed by Garofalo and Anand to characterize the steady state creep of solder. These model parameters are often incorporated as inputs in FEA simulations to properly characterize the solder response to loading.
Fatigue models.
Solder damage models take a physics-of-failure based approach by relating a physical parameter that is a critical measure of the damage mechanism process (i.e. inelastic strain range or dissipated strain energy density) to cycles to failure. The relationship between the physical parameter and cycles to failure typically takes on a power law or modified power law relationship with material dependent model constants. These model constants are fit from experimental testing and simulation for different solder alloys. For complex loading schemes, Miner's linear superposition damage law is employed to calculate accumulated damage.
Coffin–Manson model.
The generalized Coffin–Manson model considers the elastic and plastic strain range by incorporating Basquin's equation and takes the form:
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Here "∆ε" ⁄ 2 represents the elastic-plastic cyclic strain range, "E" represents elastic modulus, "σm" represents means stress, and "Nf" represents cycles to failure. The remaining variables, namely "σf","ε'f","b",and "c" are fatigue coefficients and exponents representing material model constants. The generalized Coffin–Manson model accounts for the effects of high cycle fatigue (HCF) primarily due to elastic deformation and low cycle fatigue (LCF) primarily due to plastic deformation.
Engelmaier model.
In the 1980s Engelmaier proposed a model, in conjunction with the work of Wild, that accounted for some of the limitations of the Coffin–Manson model, such as the effects of the frequency and temperature. His model takes a similar power law form:
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Engelmaier relates the total shear strain (∆γ) to cycles to failure ("Nf"). "ε'f" and "c" are model constants where "c" is a function of mean temperature during thermal cycling ("Ts") and thermal cycling frequency ("f").
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∆γ can be calculated as function of the distance from the neutral point ("LD") solder joint height ("hs"), coefficient of thermal expansion (∆"α"), and change in temperature (Δ"T"). In this case "C" is empirical model constant.
This model was initially proposed for leadless devices with tin-lead solder. The model has since been modified by Engelmaier and others to account for other phenomena such as leaded components, thermal cycling dwell times, and lead-free solders. While initially a substantial improvement over other techniques to predict solder fatigue, such as testing and simple acceleration transforms, it is now generally acknowledged that Engelmaier and other models that are based on strain range do not provide a sufficient degree of accuracy.
Darveaux model.
Darveaux proposed a model relating the quantity of volume weighted average inelastic work density, the number of cycles to crack initiation, and the crack propagation rate to the characteristic cycles to failure.
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In the first equation "N0" represents the number of cycles to crack initiation, ∆W represents inelastic work density, "K1" and "K2" are material model constants. In the second equation, da/dN represents the crack prorogation rate, ∆W represents inelastic work density, "K3" and "K4" are material model constants. In this case the crack propagation rate is approximated to be constant. "Nf" represents the characteristic cycles to failure and a represents the characteristic crack length. Model constants can be fit for different solder alloys using a combination of experimental testing and Finite Element Analysis (FEA) simulation.
The Darveaux model has been found to be relatively accurate by several authors. However, due to the expertise, complexity, and simulation resources required, its use has been primarily limited to component manufacturers evaluating component packaging. The model has not received acceptance in regards to modeling solder fatigue across an entire printed circuit assembly and has been found to be inaccurate in predicting system-level effects (triaxiality) on solder fatigue.
Blattau model.
The current solder joint fatigue model preferred by the majority of electronic OEMs worldwide is the Blattau model, which is available in the Sherlock Automated Design Analysis software. The Blattau model is an evolution of the previous models discussed above. Blattau incorporates the use of strain energy proposed by Darveaux, while using closed-form equations based on classic mechanics to calculate the stress and strain being applied to the solder interconnect. An example of these stress/strain calculations for a simple leadless chip component is shown in the following equation:
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Here α is the CTE, T is temperature, "LD" is the distance to the neutral point, E is elastic modulus, A is the area, h is the thickness, G is shear modulus, ν is Poisson's ratio, and a is the edge length of the copper bond pad. The subscripts 1 refer to the component, 2 and b refer to the board, and s refer to the solder joint. The shear stress (∆τ) is then calculated by dividing this calculated force by the effective solder joint area. Strain energy is computed using the shear strain range and shear stress from the following relationship:
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This approximates the hysteresis loop to be roughly equilateral in shape. Blattau uses this strain energy value in conjunction with models developed by Syed to relate dissipated strain energy to cycles to failure.
Other fatigue models.
The Norris–Landzberg model is a modified Coffin–Manson model.
Additional strain range and strain energy based models have been proposed by several others.
Vibration and cyclic mechanical fatigue.
While not as prevalent as thermomechanical solder fatigue, vibration fatigue and cyclic mechanical fatigue are also known to cause solder failures. Vibration fatigue is typically considered to be high cycle fatigue (HCF) with damage driven by elastic deformation and sometimes plastic deformation. This can depend on the input excitation for both harmonic and random vibration. Steinberg developed a vibration model to predict time to failure based on the calculated board displacement. This model takes into account the input vibration profile such as the power spectral density or acceleration time history, the natural frequency of the circuit card, and the transmissibility. Blattau developed a modified Steinberg model that uses board level strains rather than displacement and has sensitivity to individual package types.
Additionally, low-temperature isothermal mechanical cycling is typically modeled with a combination of LCF and HCF strain range or strain energy models. The solder alloy, assembly geometry and materials, boundary conditions, and loading conditions will affect whether fatigue damage is dominated by elastic (HCF) or plastic (LCF) damage. At lower temperatures and faster strain rates the creep can approximated to be minimal and any inelastic damage will be dominated by plasticity. Several strain range and strain energy models have been employed in this type of a case, such as the Generalized Coffin–Manson model. In this case, much work has been done to characterize the model constants of various damage models for different alloys.


Roll forming

Roll forming, also spelled roll-forming or rollforming, is a type of rolling involving the continuous bending of a long strip of sheet metal (typically coiled steel) into a desired cross-section. The strip passes through sets of rolls mounted on consecutive stands, each set performing only an incremental part of the bend, until the desired cross-section (profile) is obtained. Roll forming is ideal for producing constant-profile parts with long lengths and in large quantities.
Overview.
A variety of cross-section profiles can be produced, but each profile requires a carefully crafted set of roll tools. Design of the rolls starts with a "flower pattern", which is the sequence of profile cross-sections, one profile for each stand of rolls. The roll contours are then derived from the flower pattern profiles. Because of the high cost of the roll sets, computer simulation is often used to develop or validate the roll designs and optimize the forming process to minimize the number of stands and material stresses in the final product.
Roll-formed sections may have advantages over extrusions of a similar shapes. Roll formed parts may be much lighter, with thinner walls possible than in the extrusion process, and stronger, having been work hardened in a cold state. Parts can be made having a finish or already painted. In addition, the roll forming process is more rapid and takes less energy than extrusion.
Roll forming machines are available that produce shapes of different sizes and material thicknesses using the same rolls. Variations in size are achieved by making the distances between the rolls variable by manual adjustment or computerized controls, allowing for rapid changeover. These specialized mills are prevalent in the light gauge framing industry where metal studs and tracks of standardized profiles and thicknesses are used. For example, a single mill may be able to produce metal studs of different web (e.g. 3-5/8" to 14 inches), flange (e.g. 1-3/8" to 2-1/2") and lip (e.g. 3/8" to 5/8") dimensions, from different gauges (e.g. 20 to 12 GA) of galvanized steel sheet.
Roll forming lines can be set up with multiple configurations to punch and cut off parts in a continuous operation. For cutting a part to length, the lines can be set up to use a pre-cut die where a single blank runs through the roll mill, or a post-cut die where the profile is cut off after the roll forming process. Features may be added in a hole, notch, embossment, or shear form by punching in a roll forming line. These part features can be done in a pre-punch application (before roll forming starts), in a mid-line punching application (in the middle of a roll forming line/process) or a post punching application (after roll forming is done). Some roll forming lines incorporate only one of the above punch or cut off applications, others incorporate some or all of the applications in one line.
Process.
Roll forming is, among the manufacturing processes, one of the simplest. It typically begins with a large coil of sheet metal, between and in width, and and thick, supported on an uncoiler. The strip is fed through an entry guide to properly align the material as it passes through the rolls of the mill, each set of rolls forming a bend until the material reaches its desired shape. Roll sets are typically mounted one over the other on a pair of horizontal parallel shafts supported by a stand(s). Side rolls and cluster rolls may also be used to provide greater precision and flexibility and to limit stresses on the material. The shaped strips can be cut to length ahead of a roll forming mill, between mills, or at the end of the roll forming line.
Geometric possibilities.
The geometric possibilities can be very broad and even include enclosed shapes as long as the cross-section is uniform. Typical sheet thicknesses range from to , but they can exceed that. Length is almost unaffected by the rolling process. The part widths typically are not smaller than however they can exceed . The primary limitation is profile depth, which is generally limited to less than and rarely larger than due to roll-imparted stresses and surface speed differentials that increase with depth.
Production rates.
The production rate depends greatly on the material thickness and the bend radius; it is however also affected by the number of required stations or steps. For bend radii of 50 times the material thickness of a low carbon steel thick can range from through eight stations to through 12 stations or through 22 stations.
The time for one product to take shape can be represented by a simple function: , where is the length of the piece being formed, is the number of forming stands, is the distance between stands, and is the velocity of the strip through the rolls.
In general, roll forming lines can run from or higher, depending on the application. In some cases the limiting factor is the punching or cut-off applications.
Other considerations.
While dealing with manufacturing, Things to consider are, for example, lubrication, the effect of the process on material properties, cost, and of course safety.
Lubrication provides an essential barrier between the roll dies and the work-piece surface. It helps reducing the tool wear and allows things to move along faster. This table shows the different kinds of lubricants, their application, and the ideal metals to use them on.
The effects of the process on the material's properties are minimal. The physical and chemical properties virtually don't change, but the process may cause work-hardening, micro-cracks, or thinning at bends when discussing the mechanical properties of the material.
The cost of roll forming is relatively low. When calculating the cost of the process things such as setup time, equipment and tool costs, load/unload time, direct labor rate, overhead rate, and the amortization of equipment and tooling must be considered.Safety is also a bit of an issue with this process. The main hazards that need to be taken into consideration are dealing with moving work-pieces (up to ), high pressure rolls, or sharp, sheared metal edges.


Metal spinning

Metal spinning, also known as spin forming or spinning or metal turning most commonly, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. Spinning can be performed by hand or by a CNC lathe.
The metal spinning trade is one that dates back to antiquity and was a skill used in the Ancient Egyptian era. This is when metal spinning was limited to soft metals spun by human power on primitive lathes. The technique gave significant advances to hydro and steam power in Europe and North America in the 19th century and by the early 20th century the electric motor provided the necessary power and high-speed turning capability. With this advancement, metal spinning craftsmen were now able to spin higher quality pieces made out of brass, copper, aluminum and even stainless and cold-rolled steel.
Metal spinning does not involve removal of material, as in conventional wood or metal turning, but forming (moulding) of sheet metal over an existing shape.
Metal spinning ranges from an artisan's specialty to the most advantageous way to form round metal parts for commercial applications. Artisans use the process to produce architectural detail, specialty lighting, decorative household goods and urns. Commercial applications include rocket nose cones, cookware, gas cylinders, brass instrument bells, and public waste receptacles. Virtually any ductile metal may be formed, from aluminum or stainless steel, to high-strength, high-temperature alloys including INX, Inconel, Grade 50 / Corten, and Hastelloy. The diameter and depth of formed parts are limited only by the size of the equipment available.
Process.
The spinning process is fairly simple. A formed block is mounted in the drive section of a lathe. A pre-sized metal disk is then clamped against the block by a pressure pad, which is attached to the tailstock. The block and workpiece are then rotated together at high speeds. A localized force is then applied to the workpiece to cause it to flow over the block. The force is usually applied via various levered tools. Simple workpieces are just removed from the block, but more complex shapes may require a multi-piece block. Extremely complex shapes can be spun over ice forms, which then melt away after spinning. Because the final diameter of the workpiece is always less than the starting diameter, the workpiece must thicken, elongate radially, or buckle circumferentially.
A more involved process, known as "reducing" or "necking", allows a spun workpiece to include reentrant geometries. If surface finish and form are not critical, then the workpiece is "spun on air"; no mandrel is used. If the finish or form are critical then an eccentrically mounted mandrel is used.
"Hot spinning" involves spinning a piece of metal on a lathe while high heat from a torch is applied to the workpiece. Once heated, the metal is then shaped as the tool on the lathe presses against the heated surface forcing it to distort as it spins. Parts can then be shaped or necked down to a smaller diameter with little force exerted, providing a seamless shoulder.
Tools.
The basic hand metal spinning tool is called a "spoon", though many other tools (be they commercially produced, ad hoc, or improvised) can be used to effect varied results. Spinning tools can be made of hardened steel for use with aluminum, or from solid brass for spinning stainless steel or mild steel.
Some metal spinning tools are allowed to spin on bearings during the forming process. This reduces friction and heating of the tool, extending tool life and improving surface finish. Rotating tools may also be coated with a thin film of ceramic to prolong tool life. Rotating tools are commonly used during CNC metal spinning operations.
Commercially, rollers mounted on the end of levers are generally used to form the material down to the mandrel in both hand spinning and CNC metal spinning. Rollers vary in diameter and thickness depending the intended use. The wider the roller the smoother the surface of the spinning; the thinner rollers can be used to form smaller radii.
Cutting of the metal is done by hand held cutters, often foot long hollow bars with tool steel shaped/sharpened files attached. In CNC applications, carbide or tool steel cut-off tools are used.
The mandrel does not incur excessive forces, as found in other metalworking processes, so it can be made from wood, plastic, or ice. For hard materials or high volume use, the mandrel is usually made of metal.
Advantages and disadvantages.
Several operations can be performed in one set-up. Work pieces may have re-entrant profiles and the profile in relation to the center line virtually unrestricted.
Forming parameters and part geometry can be altered quickly, at less cost than other metal forming techniques. Tooling and production costs are also comparatively low. Spin forming, often done by hand, is easily automated and an effective production method for prototypes as well as high quantity production runs.
Other methods of forming round metal parts include hydroforming, stamping, forging and casting. These other methods generally have a higher fixed cost, but a lower variable cost than metal spinning. As machinery for commercial applications has improved, parts are being spun with thicker materials in excess of 1in (25mm) thick steel. Conventional spinning also wastes a considerably smaller amount of material than other methods.
Objects can be built using one piece of material to produce parts without seams. Without seams, a part can withstand higher internal or external pressure exerted on it. For example: scuba tanks and CO2 cartridges.
One disadvantage of metal spinning is that if a crack forms or the object is dented, it must be scrapped. Repairing the object is not cost-effective.
External links.
https://www.metalcraftspinning.com/metal-spinning/


Orient Watch

 is a Japanese watch manufacturer founded in 1950. Established as an independent company in 1950, it became a functional subsidiary of Epson in 2009 before being fully integrated into the company in 2017.
Until it was absorbed into Epson, the Orient Watch Company had primarily marketed mechanical watches (self-winding & hand-winding), but also produced quartz, light-powered (solar) and radio-controlled models. Outside of the main business, the company produced some moving parts and electronic components that were then assembled into Seiko Epson's electronic devices.
Currently, Akita Epson Corporation (formally Akita Orient Precision Instruments Co., Ltd.), a group company of Epson, manufactures all of the Orient movements in-house in Yuzawa, Akita, Japan.
History.
The origin of Orient Watch Company dates back to 1901 when Shogoro Yoshida opened a wholesale shop called "Yoshida Watch Shop" in Ueno, Taito, Tokyo, Japan. Yoshida Watch Shop was successful, selling imported pocketwatches. In 1912, Yoshida expanded his business and began producing gold wristwatch cases. In 1920, Toyo Tokei Manufacturing was established, originally producing table clocks and gauges. It was not until 1934 that Toyo Tokei Manufacturing started the production of wristwatches. In 1936, the Hino factory was built in Hino, Tokyo, Japan. For several years, Toyo Tokei Manufacturing boomed at the Hino factory. However, the company shut down in 1949 in the Japanese economic devastation following World War II.
After Toyo Tokei Manufacturing was shut down, Yoshida's wristwatch manufacturing company was reborn in 1950, founded under the name Tama Keiki Company. Tama Keiki Co. continued manufacturing watches at the Hino factory. In 1951, Tama Keiki Co. changed its name to , and in the same year the first Orient Star went on sale. Orient Watch was able to expand their visibility overseas after a memorandum trade agreement with China in 1955. The Royal Orient went on sale in 1960. Other important watches in the company's history include the "Dynamic" in 1956, "Grand Prix 100" in 1964, "Fineness" (the world's thinnest automatic wristwatch with day and date calendar function for its time) in 1967, and the "Tenbeat" in 1970.
In 2003, the Orient Technical Center (OTC) was established and the assembly of luxury watches began in Ugo, Ogachi, Akita, Japan. In 2004, the high-precision caliber 88700 movement went on sale via the Royal Orient watch line. In 2005, Orient Star Retro-Future collection was launched. In 2010, Orient Watch Co. celebrated its 60th anniversary with a limited edition model. The Royal Orient line was discontinued around 2016, likely to prevent cannibalism between it and fellow Seiko group brands Grand Seiko, and Credor. To celebrate 70 years of the Orient Star line, the Orient Star skeleton watch was introduced with a silicon escapement made using Epson's MEMS technology, which has been used in high end Seiko watches since 2009.
In 2001 Seiko Epson (one of three core companies of the Seiko Group) became the majority shareholder (52%) of the company. Orient Watch became a wholly owned subsidiary of Epson in 2009. After transferring its business to Epson, the company now exists as a dormant company. Epson Sales Japan Corporation markets the Orient watches, while Akita Epson Corporation manufactures them.


Highly accelerated stress audit

HASA (highly accelerated stress audit) is a proven test method developed to find manufacturing/production process induced defects in electronics and electro-mechanical assemblies before those products are released to market. HASA is a form of HASS (highly accelerated stress screening) – a powerful testing tool for improving product reliability, reducing warranty costs and increasing customer satisfaction.
Since HASS levels are more aggressive than conventional screening tools, a POS procedure is used to establish the effectiveness in revealing production induced defects. A POS is vital to determine that the HASS stresses are capable of revealing production defects, but not so extreme as to remove significant life from the test item. Instituting HASS to screen the product is an excellent tool to maintain a high level of robustness and it will reduce the test time required to screen a product resulting in long term savings. Ongoing HASS screening assures that any weak components or manufacturing process degradations are quickly detected and corrected. HASS is not intended to be a rigid process that has an endpoint. It is a dynamic process that may need modification or adjustment over the life of the product.
HASS aids in the detection of early life failures. HASA's primary purpose is to monitor manufacturing and prevent any defects from being introduced during the process. A carefully determined HASA sampling plan must be designed that will quickly signal when process quality has been degraded.


DELMIA

Dassault Systèmes DELMIA is a Global Industrial Operations software that specializes in digital manufacturing and manufacturing simulation.
The acronym DELMIA means: Digital Enterprise Lean Manufacturing Interactive Application


Solder paste

Solder paste is used in the manufacture of printed circuit boards to connect surface mount components to pads on the board. It is also possible to solder through-hole pin in paste components by printing solder paste in and over the holes. The sticky paste temporarily holds components in place; the board is then heated, melting the paste and forming a mechanical bond as well as an electrical connection. The paste is applied to the board by jet printing, stencil printing or syringe; then the components are put in place by a pick-and-place machine or by hand.
Use.
A majority of the defects in circuit-board assembly are caused due to issues in the solder-paste printing process or due to defects in the solder paste. There are many different types of defects possible, e.g. too much solder, or the solder melts and connects too many wires (bridging), resulting in a short circuit. Insufficient amounts of paste result in incomplete circuits. Head-in-pillow defects, or incomplete coalescence of ball grid array (BGA) sphere and solder paste deposit, is a failure mode that has seen increased frequency since the transition to lead-free soldering. Often missed during inspection, a head-in-pillow (HIP) defect appears like a head resting on a pillow with a visible separation in the solder joint at the interface of the BGA sphere and reflowed paste deposit. An electronics manufacturer needs experience with the printing process, specifically the paste characteristics, to avoid costly re-work on the assemblies. The paste's physical characteristics, like viscosity and flux levels, need to be monitored periodically by performing in-house tests.
When making PCBs (printed circuit boards), manufacturers often test the solder paste deposits using SPI (solder paste inspection). SPI systems measure the volume of the solder pads before the components are applied and the solder melted. SPI systems can reduce the incidence of solder-related defects to statistically insignificant amounts. Inline systems are manufactured by various companies such as Delvitech (Switzerland), Sinic-Tek (China), Koh Young (Korea), GOEPEL electronic (Germany), CyberOptics (US), Parmi (Korea) and Test Research, Inc. (Taiwan). Offline systems are manufactured by various companies such as by VisionMaster, Inc. (US) and Sinic-Tek (China).
Composition.
A solder paste is essentially powdered solder suspended in flux paste. The tackiness of the flux holds components in place until the soldering reflow process melts the solder. As a result of environmental legislation, most solders today, including solder pastes, are made of lead-free alloys.
Classification.
By size.
The size and shape of the metal particles in the solder paste determines how well the paste will "print". A solder ball is spherical in shape; this helps in reducing surface oxidation and ensures good joint formation with the adjoining particles. Irregular particle sizes are not used, as they tend to clog the stencil, causing printing defects. To produce a quality solder joint, it's very important for the spheres of metal to be very regular in size and have a low level of oxidation.
Solder pastes are classified based on the particle size by IPC standard J-STD 005. The table below shows the classification type of a paste compared with the mesh size and particle size. Some suppliers use propriety particle size descriptions, Henkel/Loctite descriptions are given for comparison.
By flux.
According to IPC standard J-STD-004 "Requirements for Soldering Fluxes", solder pastes are classified into three types based on the flux types:
Rosin based fluxes are made with rosin, a natural extract from pine trees. These fluxes can be cleaned if required after the soldering process using a solvent (potentially including chlorofluorocarbons) or saponifying flux remover.
Water-soluble fluxes are made up of organic materials and glycol bases. There is a wide variety of cleaning agents for these fluxes.
A no-clean flux is designed to leave only small amounts of inert flux residues. No-clean pastes save not only cleaning costs, but also capital expenditures and floor space. However, these pastes need a very clean assembly environment and may need an inert reflow environment.
Properties of solder paste.
In using solder paste for circuit assemblies, one needs to test and understand the various rheological properties of a solder paste.
Use.
Solder paste is typically used in a stencil-printing process by a solder paste printer, in which paste is deposited over a stainless steel or polyester mask to create the desired pattern on a printed circuit board. The paste may be dispensed pneumatically, by pin transfer (where a grid of pins is dipped in solder paste and then applied to the board), or by jet printing (where the paste is ejected onto the pads through nozzles, like an inkjet printer).
As well as forming the solder joint itself, the paste carrier/flux must have sufficient tackiness to hold the components while the assembly passes through the various manufacturing processes, perhaps moved around the factory.
Printing is followed by a complete reflow soldering process.
The paste manufacturer will suggest a suitable reflow temperature profile to suit their individual paste. The main requirement is a gentle rise in temperature to prevent explosive expansion (which can cause "solder balling"), yet activate the flux. Thereafter, the solder melts. The time in this area is known as "Time Above Liquidus". A reasonably rapid cool-down period is required after this time.
For a good soldered joint, the proper amount of solder paste must be used. Too much paste may result in a short circuit; too little may result in poor electrical connection or physical strength. Although solder paste typically contains around 90% metal in solids by weight, the volume of the soldered joint is only about half that of the solder paste applied. This is due to the presence of flux and other non-metallic agents in the paste, and the lower density of the metal particles when suspended in the paste as compared to the final, solid alloy.
As with all fluxes used in electronics, residues left behind may be harmful to the circuit, and standards (e.g., J-std, JIS, IPC) exist to measure the safety of the residues left behind.
In most countries, "no-clean" solder pastes are the most common; in the United States, water-soluble pastes (which have compulsory cleaning requirements) are common.
Storage.
Solder paste must be refrigerated when transported and stored in an airtight container at a temperature between 0-10 °C. It should be warmed to room temperature for use.
Recently, new solder pastes have been introduced that remain stable at 26.5 °C for one year and at 40 °C for one month.
Exposure of the solder particles, in their raw powder form, to air causes them to oxidize, so exposure should be minimized.
Evaluation.
The main reason why evaluation of solder paste is necessary, is because 50-90% of all defects result from printing problems. Hence, paste evaluation is critical.
This procedure is quite thorough, yet minimizes the amount of testing required to differentiate between excellent and poor solder pastes. If multiple solder pastes are evaluated, the procedure can be used to eliminate the poor pastes from their poor printing quality. Further testing, such as solder reflow performance, solder joint quality, and reliability testing can then be performed on the solder paste finalists.
Concerns.
The main concerns about solder paste are:
These three concerns helped to spawn three enclosed systems for printing.


Demand flow technology

Demand Flow Technology (DFT) is a strategy for defining and deploying business processes in a flow, driven in response to customer demand. DFT is based on a set of applied mathematical tools that are used to connect processes in a flow and link it to daily changes in demand.
DFT represents a scientific approach to flow manufacturing for discrete production. It is built on principles of demand pull where customer demand is the central signal to guide factory and office activity in the daily operation. DFT is intended to provide an alternative to schedule-push manufacturing which primarily uses a sales plan and forecast to determine a production schedule.
History.
It was created by John R. Costanza, an executive with operations management experience at Hewlett Packard and Johnson & Johnson. Costanza, who was later nominated as a Nobel Laureate in Economics for Working Capital Management, founded the John Costanza Institute of Technology in Englewood, CO in 1984 to provide consulting and education services for manufacturers to implement the methodology.
DFT uses applied mathematical methods to link raw and in-process materials with units of time and production resources in order to create a continuous flow in the factory. The objective is to link factory processes together in a flow and drive it to customer demand instead of to an internal forecast that is inherently inaccurate.
Early adopters of DFT included American Standard Companies General Electric and John Deere (Deere & Company).
In the early years, DFT was regarded as a method for "just-in-time" (JIT), which advocated manufacturing processes driven to actual customer demand via Kanban. It was introduced as a way for American manufacturers to adopt Japanese production techniques, such as Toyota Production System (TPS), whilst avoiding some of the cultural conflicts in applying Japanese business methods in an American company. Later, it has come to be seen as a lean manufacturing method that allows factories to implement techniques such as one-piece flow, TAKT-based line design, Kanban material management and demand-driven production.
Demand Flow Technology is promoted as a method for any product, any day, any volume. In 2001, Costanza was awarded a patent for this approach for mixed-model manufacturing.
Principles.
Demand-driven manufacturing.
The central tenet to DFT is the primacy of customer demand in daily execution of the operation. According to Aberdeen Group,
DFT is a pathway to achieve demand-driven manufacturing capability. It is used as a framework to guide the design, implementation and deployment of demand driven manufacturing in a repeatable form. In this way, it is similar original concept of Just-in-Time (JIT) that was first deployed in Japanese manufacturers using a foundation of total quality management. More recently, Just-in-time has been more commonly used to describe supplier delivery methods, rather than a production philosophy. DFT assumes basic process capability that can arise from TQM and statistical process control (SPC) principles and embeds it in a framework of management that can more easily achieve demand driven in a repeatable way.
As a result, In-Progress and Finished inventories are all but eliminated, converted permanently into cash at full market value through much faster response to customer orders.
Cash released from Working Capital in this way no longer has to be reinvested in inventory. It becomes available to retire debt, fund growth and innovation.
Mixed-model production.
Mixed-model production is the production of a wide range of product models using a certain degree of shared resources and common material. It is commonly accepted that modern manufacturing places a greater pressure on producers for more choice in the product offering. Products are increasingly assembled from standard components and sub-assemblies, using machines and automated systems as well as manual labour. DFT is designed to handle this mix and provide a way to establish mixed-model production lines.
A production schedule based on MRP will tend to cope with high product mix by allocating each model to a multiple of a shift or a day. This means that the whole product mix is supplied across a scheduling cycle of a multiple of weeks. This tends to extend the lead-time or increase dependency on the forecast. DFT offers “The ability to accommodate a range of volumes for any product, any day, based on the direction of actual customer demand”.
Product synchronization.
The first tool to be used in a DFT implementation, product synchronization is a definition of relationship of processes in a flow to build a product. It takes the form of a diagram, usually created in pen and paper or whiteboard and formalized with a visualization program such as Microsoft PowerPoint or Visio. It displays how the processes relate to each other in a flow, with the conversion of raw material to finished goods. A process is defined by "A logical grouping of value-adding work performed to a common volume".
Sequence of events (SoE).
Each of the processes in the product synchronization requires a standard process definition. In DFT, the sequence of events provides this definition. In "The Quantum Leap", written by Costanza, the sequence of events is defined as "[t]he definition of the required work and quality criteria to build a product in a specific production process."
The SoE usually takes the form of a table with the product code, process ID, task description and sequence, required work and set-up time for machines and labour, and quality check criteria. The SoE intends to define times that are reasonable, realistic and repeatable to perform to the necessary quality. Many of the strengths and criticisms of DFT as a methodology stem from the SoE. The SoEs are the foundation of process definition but are not used as work instructions. To communicate standard work at the work center, operation method sheets are used.
In an MRP systems environment, the SoE represents a drill-down from the routing that provides a tabular view of the Product Synchronization at the process level. A DFT manufacturer would therefore use the SoE as the master record of process definition and derive routings and ISO documentation from it.
Operation method sheets.
These are visual description of work in motion, materials and the required quality check. In the purest form, operation method sheets are drawn in wire-frame to show the significant contours of the product form and clearly represent work in motion and quality without visual noise. The OMS has three stages of activity: total quality check, work, and verify. This establishes the concept where each operator checks the output quality of the operation immediately upstream. This can contribute to a total quality culture and parts-per-million capability.
Mixed-model process map.
The sequence of events and product synchronization define how tasks and quality check compose the process for any given product. The mixed-model process map shows how products and processes form a requirement for resources. In such a map, the products and processes form a matrix with products as rows and processes as columns. At the intersection are most commonly actual times (standard times at the process from the sequence of events), but could also display yield and optionality ratios.
Demand at capacity.
Demand at capacity is the volume of production for a single product item at capacity. It is a fixed value that defines the maximum daily rate of supply. The Demand-at-Capacity is often confused with the daily rate of production. In contrast to Toyota Production System, and many other lean manufacturing derivatives, a DFT line is designed for variable output rates according to daily demand. Thus, the demand data that are used for line design represent a limit quantity not an actual rate of supply. The relationship between the Dc and the average daily demand will be driven by the required service level of the product item to market demand. A higher service level will call for capacity that can supply a higher daily rate than the average over a long range. This will likely affect the resource productivity and inventory levels. A greater mix on the line is able to provide a higher level of service for any given level of resources and inventory.
Effective hours.
The effective hours is the time available for a given resource to produce product or perform process set-up or changeover. It is defined per shift and represents the total available time to perform tasks set in the SoE. Non-productive time such as equipment maintenance, breaks, 5S activity and continuous improvement is deducted from effective hours. Setup time is included as it is arguably a form of productive time and calculations for batch size optimization and dynamic Kanban will require setup and run-time to be managed from a common pool of resource time.
Takt & Operational Cycle-Time, OP c/t.
Takt-time is the ratio of time to volume at capacity and in DFT is expressed as
Where HE is Effective Hours, S is the number of shifts and DC is the demand at capacity, a daily rate set for design purposes at some point 2 to 5 years into the future. This ratio can be expressed for finished products at the end of the line and is referred to as Takt-Time. It can also apply at the process where bill of material relationships, process yield and optionality can affect the dependent volume for any given Dc at the finished goods level. At the process level, this ratio is known as operational cycle-time.
Takt time is typically used to calculate the "line design" or number and disposition of physical resources required to produce a given mix and volume of products that changes on a daily basis according to customer demand.
Uniquely to DFT Takt time is constant, based on a fixed mix and product volume which is set for factory design purposes 2 to 5 years into the future. This allows for a stable "line design" that does not need to change on a daily basis. Daily changes in mix and volume are accommodated in DFT by adjusting the number of people working in production. Those not required to meet the Daily Rate (Dr) are free to spend quality time in training and continuous improvement activities.
Weekly scheduling cycles to achieve level-loading of mix and volume, which cause significant planning delays, are eliminated. It becomes possible to produce any product on any day in response to real customer demand making possible a true Demand Flow.
As a result, In-Progress and Finished inventories are all but eliminated, converted permanently into cash at full market value through much faster response to customer orders.
Cash released from Working Capital in this way no longer has to be reinvested in inventory. It becomes available to retire debt, fund growth and innovation etc.
Material Kanban.
DFT shares a conventional definition of material Kanban based on a visual signal to replenish a point of consumption with required material. A typical material Kanban system in DFT is "Single Card, Multiple Container" and enables card or container quantities to be consumed and replenished without shortages.
Material Kanban provides an alternative to kitting as a way of issuing material to the production floor. A DFT environment will strive to simplify the definition of warehouse locations for material and reduce the number of transactions required to control the flow of material during production. The aim of Material Kanban is to connect the material flow with actual requirement at the process and provide a more robust availability of parts to production whilst reducing the response-time to the customer.
Production Kanban.
Production Kanban is designed for a replenishment quantity that may be smaller than a lot size or batch. It is based on a "dual card Kanban" system where a "move" card or container represents the quantity required by the downstream point of consumption and a "produce" card is kept on a display board and accumulates to a replenishment batch.
Demand-based management.
Demand-based management is an approach that defines tolerance capability for demand in order to unify material and production planning under conditions of demand uncertainty. It uses "flex fences" to set the upper and lower boundaries of supply against a definition of the current daily rate of demand. The current rate is usually some kind of smoothed average and will move over time. The flex-fences will be different for different product items or groups and should be calculated individually. Order policies, purchasing, inventory and production capacity will all be set against these flex fence boundaries, so these calculations will sit at the heart of operations planning.
Unfortunately, this is a calculation-intensive and critical process that is largely unsupported by MRP/ERP systems. The lack of system tools and clash with conventional MRP planning routine are primary reason why demand-based management has not had the same level of adoption experienced by the rest of the DFT principles.
Value and results.
Companies that implement DFT are typically looking for an improvement in the response to customer demand. This is reflected in the lead-time or replenishment time for finished product and will affect the level of inventory that is held to buffer response requirements.
Effective response to demand can be described as a distribution curve, with some orders taking longer to fill than others. The result is variation and uncertainty in the manufacturer’s ability to serve the market. Working capital is required to hedge this response lag and uncertainty.
DFT aims to reduce both the variation and duration of response to demand. This can be seen as a more capable fulfillment that provides a higher level of customer service at a lower level of working capital. The intended results are improvement in delivery performance together with increased cash-flow and return on working capital.
Applications.
Demand flow technology is applicable in a wide range of product environments and has been successfully deployed in many different industries. Companies who have embraced demand flow technology include John Deere, Flextronics, American Standard Companies, Trane, AstraZeneca and many others. It has a strength in those manufacturing operations that are expected to supply a high mix to an unpredictable and volatile market. It is often seen as the science behind flow manufacturing for discrete manufacturers, whose products do not naturally flow across the manufacturing processes.
Advantages and criticisms.
Advantages.
It is simple.
Demand flow technology provides a simple, logical method based on applied mathematics. The technique is based on simple operators of addition, subtraction, multiplication and division so it does not rely on advanced mathematics.
It is repeatable.
DFT forms a step-by-step guide to converting production from a scheduled-push to a demand-pull and flow system. Although it is applicable to a wide range of products, the steps are consistent and work in the same way. It does not depend on the judgment of an expert in the same way as lean or Six Sigma and can be taught to a broader audience through short training workshops.
It is effective.
At its heart, DFT formalizes the natural flow of material, processes and information required to build a product. It is not so much an invented technology as a description of the optimal way to align a factory towards customer demand.
It is customer-centric.
DFT places the customer at the center of the operation. It enables companies to formalise a customer-centric view with practical tasks and actions that guide behaviour in the organisation. It moves the concept of customer-driven to an achievable plan of action beyond a statement of philosophy.
It aligns business and customer goals.
The concept of maximizing shareholder value is often seen as a conflict with the quality of customer service. Demand Flow Technology, if applied correctly, can unify financial and customer objectives in a holistic approach to managing operating capital and growing a business.
Criticisms.
It is constrained to the factory.
Demand flow techniques have been widely applied to the factory, yet have failed to gain widespread acceptance in corporate management. All too often, it tends to be limited to production planning whilst operations and material planning continue to be dominated by use of ERP/MRP systems. The holistic ideal of demand flow may be fractured by this conflict.
It is unsupported by systems.
Major ERP/MRP vendors have largely ignored the advantages of Demand Flow techniques, or been acquired before their products have had a chance to gain market share. The advocates and users of Demand Flow have largely failed to challenge the inadequate logic that conventional MRP uses for planning capacity and production resources As a result, manufacturers are forced to rely on an outdated routine for planning that is largely unchanged since the 1960s.
It requires process definition and discipline.
DFT aims to apply a standard process definition of product to daily requirements of demand. This favours processes that are capable and defined to the task level. This is sometimes a level of detail and discipline absent from the organisation. The creation and maintenance of Sequence of Events documentation involves extensive manual work. There are powerful advantages to quality and capability in performing this work, but success usually depends on management commitment to change beyond the narrow actions of a DFT implementation.


Free machining steel

Free machining steel is steel that forms small chips when machined. This increases the machinability of the material by breaking the chips into small pieces, thus avoiding entanglement in the machinery. This enables automatic equipment to run without human interaction. Free machining steel with lead also allow for higher machining rates. Free machining steel costs 15 to 20% more than standard steel, but this higher cost is offset by increased machining speeds, larger cuts, and longer tool life.
The disadvantages of free machining steel are: ductility is decreased; impact resistance is reduced; copper-based brazed joints suffer from embrittlement with bismuth free machining grades; shrink fits are not as strong.
Types.
There are four main types of free machining steel: "leaded", "resulfurized", "rephosphorized" and "super". Super free-machining steels are alloyed with tellurium, selenium, and bismuth.
Mechanics.
Free machining steels are carbon steels that have sulfur, lead, bismuth, selenium, tellurium, or phosphorus added. Sulfur forms the compound manganese sulfide, which is soft and acts as a chip-breaking discontinuity. It also acts as a dry lubricant to prevent a built up edge on the cutting tool. Lead works in a similar way to sulfur. Bismuth achieves a free machining steel by melting into a thin film of liquid for a fraction of a microsecond to lubricate the cut. Other advantages to bismuth include: more uniformly distributed because of its similar density to iron; more environmentally friendly, as compared to lead; still weldable.


Burr (edge)

A burr is a raised edge or small piece of material that remains attached to a workpiece after a modification process.
It is usually an unwanted piece of material and is removed with a deburring tool in a process called 'deburring'. Burrs are most commonly created by machining operations, such as grinding, drilling, milling, engraving or turning. It may be present in the form of a fine wire on the edge of a freshly sharpened tool or as a raised portion of a surface; this type of burr is commonly formed when a hammer strikes a surface. Deburring accounts for a significant portion of manufacturing costs.
In the printmaking technique of drypoint, burr, which gives a rich fuzzy quality to the engraved line, is highly desirable—the great problem with the drypoint medium is that the burr rapidly diminishes after as few as ten impressions are printed.
Types.
There are three types of burrs that can be formed from machining operations: "Poisson burr", "rollover burr", and "breakout burr". The rollover burr is the most common. Burrs may be classified by the physical manner of formation. Plastic deformation of material includes lateral flow (Poisson burr), bending (rollover burr), and tearing of material from the workpiece (tear burr). Solidification or redeposition of material results in a recast bead. Incomplete cutoff of material causes a cutoff projection.
Burrs can be minimized or prevented by considering materials, function, shape, and processing in the design and manufacturing engineering phases of product development.
Burrs in drilled holes cause fastener and material problems. Burrs cause more stress to be concentrated at the edges of holes, decreasing resistance to fracture and shortening fatigue life. They interfere with the seating of fasteners, causing damage to fastener or the assembly itself. Cracks caused by stress and strain can result in material failure. Burrs in holes also increase the risk of corrosion, which may be due to variations in the thickness of coatings on a rougher surface. Sharp corners tend to concentrate electrical charge, increasing the risk of static discharge. Burrs in moving parts increase unwanted friction and heat. Rough surfaces also result in problems with lubrication, as wear is increased at the interfaces of parts. This makes it necessary to replace them more frequently. Electrical charge buildup can cause corrosion.
Deburring.
There are many deburring processes, but the most common are mass-finishing, spindle finishing, media blasting, sanding, grinding, wire brushing, abrasive flow machining, electrochemical deburring, electropolishing, thermal energy method, machining, water jet deburring, and manual deburring.
Manual.
"Manual deburring" is the most common deburring process because it is the most flexible process. It also only requires low cost tools and allows for instant inspection.
Manual deburring is either done with tools like scrapers, files, sandpaper, stones and reamers or with handheld power tools that use abrasive points, sandpaper, or cutters similar to those used to deburr during machining.
Electrochemical.
"Electrochemical deburring" is the use of electrochemical machining to deburr precision work pieces and edges that are hard-to-reach, such as intersecting holes. The process uses a salt or glycol solution and electricity to dissolve the burr. The electric current is applied with a specialized tool to reach the burr location. Burrs are removed in 5 to 10 seconds, while the rest of the work piece is unaffected.
Thermal.
"Thermal energy method" (TEM), also known as "thermal deburring", is a deburring process used to remove hard-to-reach burrs or burrs from multiple surfaces at the same time. The process uses an explosive gas mixture to provide thermal energy to burn off the burrs. It is the fastest burr removal process, requiring only 20 milliseconds to remove a burr.
The process starts by loading the workpiece into an explosion-proof chamber, which is then sealed and clamped with approximately . The chamber is then evacuated of air and filled with an oxygen and fuel mix; this mixture is pressurized to . An electrical igniter then ignites the mixture, which burns for approximately 20 milliseconds, causing all of the sharp corners and burrs to burn away. The peak temperature reaches .
Cryogenic.
"Cryogenic deburring" is a cryogenic process used to remove burrs and flash from plastic and die cast workpieces. The process works by tumbling and/or abrasively blasting the workpieces at cryogenic temperature levels. The low temperatures (approximately ) are achieved using liquid nitrogen, liquid carbon dioxide, or dry ice. This low temperature brings the material below its embrittlement temperature, which causes the flash or burrs to be easily removed via tumbling or media blasting. This process has been around since the 1960s to deflash plastic and rubber. Common materials that are typically cryogenically deburred with blast media include PEEK, nylon, Teflon, Delrin, polypropylene, polycarbonate, acetal, PTFE, PET, HDPE, PVC, ABS and many others.
Mechanical.
"Mechanical deburring" is a deburring process that either mechanically grinds a burr off of metal or rolls the edge of the dangerous slit or sheared metal burrs into itself. Rolled mechanical deburring was first developed in the 1960s by Walter W. Gauer from Gauer Metal Product, Inc. as a means to speed up the process of hand deburring strips of metal that were used in bakery racks.
Water jet.
One of the main benefits of "waterjet deburring" is a high level of precision and repeatability - and for this reason, CNC control is used. This eco-friendly process uses high-pressure water to remove loose burrs and chips even in deep holes – all while leaving the parts cleaner and free of debris. Pressurized water is precisely focused via CNC control to remove burrs and chips in and around parts. Depending on the cleanliness specifications, this can be performed submerged or in an open-air environment. Open-air washing/deburring targets specific areas of the part where the water jet is focused. Submerged will clean the entire part, internally and externally.
Ultrasonic Deburring.
Powerful ultrasonic waves are irradiated against the tank containing the liquid.
This technology removes burrs by the pressure generated within the liquid as cavities are generated and dissipated.


Copper pour

In electronics, the term copper pour refers to an area on a printed circuit board filled with copper (the metal used to make connections in printed circuit boards). Copper pour is commonly used to create a ground plane. Another reason for using copper pour is to reduce the amount of etching fluid used during manufacturing.
A distinctive feature of copper pour is the "backoff" (or "stand-off") - a certain distance between the copper pour and any tracks or pads not belonging to the same electrical net. A copper pour therefore looks like it flows around other components, with the exception of pads which are connected to the copper pour using thermal connections.
PCB designers today almost invariably use completely solid areas of copper pour that completely cover the remaining area outside those tracks, pads, and stand-off regions. Many early PCBs have a "hatched copper pour", sometimes called a "cherry pie lattice".
While solid copper pour provides better resistive characteristics, hatched copper pour is used to balance the heat and dilatation on both sides of the board in order to avoid warping of certain substrate.
Heating might cause gas bubbles between solid copper pour and certain substrates. Furthermore, it might be possible to adjust the impedance of high frequency traces by using hatched copper pour in order to reach better signal quality.


Retrogression heat treatment

Retrogression heat treatment (RHT) is a heat treatment process that rapidly heat treats age-hardenable aluminum alloys. Mainly induction heating is used for RHT. In the past, it was mainly used for 6061 and 6063 aluminum alloys. Therefore, forming of complex shapes is possible, without creating damages like cracks. Even hard tempers (for example -T6) can be formed easily after subjecting these alloys to RHT.


ViTrox

ViTrox Corporation Berhad  is a Malaysian based electronics company located at Penang, Malaysia. ViTrox specializes in designing and developing automated vision inspection system and equipment testers for the semiconductor and electronic packaging industries as well as electronic communications equipment.
The name ViTrox reflects the core business of the company, which is machine vision and electronics.
ViTrox's core products are its Machine Vision System (MVS), Automated Board Inspection (ABI) and Electronics Communication System (ECS).
History.
ViTrox Technologies was established in 2000 in Penang by Chu Jenn Weng and Steven Siaw Kok Tong who studied together at University Sains Malaysia in the 1990s inside their bedroom garage. Chu had an inspiration of becoming an entrepreneur after visiting Hewlett Packard garage in USA. Therefore, after he had worked in a multinational corporation (MNC) for several years, he roped in Siaw as a business partner to handle the operations and marketing parts of business while Chu focus on the technical sides of the operations. As their business expanded, the business operations was moved from their bedroom garage to the Krystal Point, Bayan Baru. As the business continued to grow, business operations moved to several places.
In 2006, ViTrox secure exclusive contracts with SRM, another Penang based MNC specializing in electric test handler for 10 years estimated to be worth of RM100 million.
During the financial crisis of 2007–2008, ViTrox Technologies purchased AXI and AOI business unit from Agilent as the former company decides to exit the business to focus on the electronic test.
With the purchase of AXI and AOI from Agilent, ViTrox Technologies now have 4 different segments of business units which are system integrator and provider of high-speed machine vision inspection systems, automated optical inspection, X-Ray inspection and electronics communication systems to cater different kind of vision test for different segments of customer bases in semiconductor related industries worldwide. ViTrox key customers are in the back-end semi-conductor assembly and packaging industry as well as the electronics manufacturing and contract manufacturing industry.
In 2013, ViTrox have an internal target of "555 strategy" which meant have the annual turnover of MYR500 million, have 500 employees by the end of 2015. But as the year 2015 is reaching near with the target is nowhere near the sights, Chu switched its plans to "Asia Expansion Strategy" whereby they are focusing in Asia regions naming China, Taiwan, Japan, Korea, Indonesia and the Philippines.
Business unit.
ViTrox core products are divided into 4 categories:
(i) machine vision system (MVS) is used in the back-testing of semiconductor components, utilizing cameras and sensors to automatically detect dimensional/visual defects and surface markings by capturing images from different angles for computer analysis, performing various inspections such as mark and orientation assessment, pad and package inspection, lead/ball co-planarity examination, and mark/lead inspection within the tape.
(ii) automated optical inspection (AOI) identify defects that arise during the production of printed circuit boards (PCB), flexible printed circuit boards (FPC), and high density interconnect (HDI) substrates.
(iii) automated X-ray inspection (AXI) system, utilizes X-rays instead of optical cameras to provide a non-invasive inspection solution, enabling it to inspect hidden solder joints, component shields, and high-density server boards.
(iv) electronic communication system (ECS) utilizes X-rays instead of optical cameras to provide a non-invasive inspection solution, enabling it to inspect hidden solder joints, component shields, and high-density server boards.
Office Locations.
Currently, there are total of 8 offices branches across the globe.


Poly diamond powder

Poly diamond powder is a kind of synthetic diamond which is synthesized through explosion method. Compared to mono diamond, poly diamond powder has more crystal edges and grinding surface, every crystal edges have grinding force. During the polishing process, the big grit can fall into small pieces so it can keep the sustaining grinding force without scratches.
Production method.
Detonation——Purification——Shaping——Grading——Finished Product
Application.
Poly diamond powder mainly is used in sapphire substrate, diaphragm, and LED chips etc.


Arc blow

Arc blow is the, usually unwanted, deflection of the arc during arc welding.
There are two types of arc blow commonly known in the electric welding industry: "magnetic" and "thermal".
Magnetic arc blow.
Magnetic arc blow or "arc wander" is the deflection of welding filler material within an electric arc deposit by a buildup of magnetic force surrounding the weld pool. Magnetic arc blow can occur because of:
Arc blow tends to occur if the material being welded has residual magnetism at a certain level, particularly when the weld root is being made, and the welding current is direct current (DC positive or negative).
Magnetic arc blow is popularly attributed to a change in the direction of current as it flows into and through the workpiece. Magnetic arc blow is known to begin at field densities as low as 10 gauss and becomes severe at densities of, equal to or greater than, 40 gauss; it is directional and can be classified as "forward" or "backward" moving along the joint, but can occasionally occur to the sides depending on the orientation of the poles to the workpiece.
Magnetic arc blow is more common in DC welding than in AC welding.
Thermal arc blow.
Thermal arc blow is widely attributed to variations in resistance within the base metal created by the weld pool as it is moved across the workpiece. Thermal arc blow can occur because of:
Thermal arc blow is not as severe as magnetic arc blow, but can still leave undesirable defects in the weld deposit.


Firecracker welding

Firecracker welding is a rarely used form of shielded metal arc welding (SMAW).
A flux-coated electrode, as used for SMAW (manual stick welding), is laid horizontally above a close-fitting butt weld. An arc is struck at one end of the electrode, which then burns along the length of the electrode. The electrode is held in place by either copper blocks, clamps or adhesive tape.
Process.
Manual metal arc welding is relatively slow, as much time is spent stopping to fit new electrodes and to clean slag before restarting. Firecracker welding allows a weld the entire length of an electrode to be welded in one pass, without pausing. Extra-long electrodes may be used to increase the length that may be welded in one pass, up to 72 inches (1.8 meters).
The need to clean slag from a manual weld before restarting increases the risk of accidental slag inclusion in the finished weld. This risk is avoided through the use of firecracker welding. As the electrode position is also constant relative to the weld, the risk of porosity is also reduced, to the level of a skilled welder. The process is also suitable for use in areas with limited access. Once started it continues automatically, without needing enough space for a skilled welder with sight of the weld.
One drawback is that the size of the bead deposited is limited by the cross-section of the electrode, as there is no scope for manually weaving the arc to deposit more rod in less weld length. For this reason, the flux coating often contains iron powder, to give additional deposition. The rod coating is generally the same as for manual arc, with no change being required. Experiments have been conducted where the coating was thinned on the side in contact with the workpiece, although this does not seem to show a great advantage.
History of application.
The process was developed in Austria in 1938 by Georg Hafergut. The process was known as "Elin-Hafergut" welding.
The process, with its suitability for long welds in flat sheet was recognised as being useful for shipbuilding and bridgebuilding and has been studied specifically for these applications.


Weld pool

In metalworking, weld pool commonly refers to the dime-sized workable portion of a weld where the base metal has reached its melting point and is ready to be infused with filler material. The weld pool is central to the success of the welding process. It was first observed in oxy-fuel welding by Fouché & Picard in 1903, after the discovery of acetylene by Edmund Davy in 1836.
The weld pool must be carried along the joint in a consistent width and depth, and the motion used to carry the weld pool has a direct effect on the quality of the weld bead. A weld made by starting and carrying a weld pool, without the addition of a filler material, is called an autogenous weld.


Profitability analysis

In cost accounting, profitability analysis is an analysis of the profitability of an organisation's output. Output of an organisation can be grouped into products, customers, locations, channels and/or transactions.
Description.
In order to perform a profitability analysis, all costs of an organisation have to be allocated to output units by using intermediate allocation steps and drivers. This process is called costing. When the costs have been allocated, they can be deducted from the revenues per output unit. The remainder shows the unit margin of a product, client, location, channel or transaction.
After calculating the profit per unit, managers or decision makers can use the outcome to substantiate management decisions. Managers can decide to stop selling loss making products, to reduce costs for loss making customers or to increase sales in profitable locations.
Pareto analysis.
In profitability analysis it is possible to perform a Pareto analysis by ranking output units from most profitable to least profitable. By doing so it is possible to create a so-called 'Whale Curve', graphically showing the potential margin of an organisation.


Scissel

Scissel is the scrap produced in the punching of coin blanks from a continuous strip of metal. The scrap is collected and remelted to form new sheets, or may be melted for manufacture of other alloys.


Ingersoll Machine Tools

Ingersoll Machine Tools is a manufacturer located in Rockford, Illinois that produces large scale machine tools for use in metal cutting, 3D Printing, and automated fiber placement.
History.
The company was founded in 1891 by Winthrop Ingersoll when he moved W.R. Eynon & Co. from Cleveland, Ohio to Rockford. Originally, Ingersoll Machine Tools focused almost entirely on milling machinery and processes for metal removal. It acquired contracts from General Electric and, by 1917, was closely involved with wartime production and had a workforce of 600.
Ingersoll went on to produce customized machines for industries such as airplane and auto manufacturing. In the period from the 1960s to the 1980s, the company employed around 2,000 people at its plant, also developing CNC technologies to introduce automation into its manufacturing processes.
Bankruptcy.
In 2003, Ingersoll International went bankrupt. The company was purchased by the Italian Camozzi Group. Since its purchase by Camozzi, the company has attempted to redefine its place in the market, continuing with milling machines but also expanding into other areas.
Present activities.
Ingersoll Machine Tools is a supplier of machine tools, including large five axis milling machines, large 3D Printers, and automated fiber placement (AFP) for the aerospace industry. It has made the wing molds for Mitsubishi, supplier of the wings on the Boeing 787. In 2010, it received Best Supplier Award from Alenia Aeronautica.
Ingersoll's AFP machines are also installed at UTC Aerospace Systems' (formerly Goodrich Corporation) facilities in Riverside, California. At this facility, the machines are used to layup the engine nacelles for the Boeing 787 and Airbus A350.
Ingersoll has also continued working in the metal cutting industry, with much of its contract production being for the Defense, Aerospace, and wind industry. It has also sold machinery to NASA.
In 2019, the Guinness Book of Worlds Records certified that Ingersoll has produced the World's Largest 3D Printer. The product, named MasterPrint, was installed at the University of Maine.
In addition to building machine tools, Ingersoll has built and installed large telescopes for Astronomy research. Most recently, they were selected to build the mount for the Giant Magellan Telescope, which will be installed in Chile.
Ingersoll Machine Tools was awarded the 2020 Manufacturer of the Year by the Rockford, Illinois Chamber of Commerce.
External links.


Net investment

In economics, net investment is spending which increases the availability of fixed capital goods or means of production and goods inventories. It is the total spending on newly produced physical capital (fixed investment) and on inventories (inventory investment)—that is, gross investment—minus replacement investment, which simply replaces depreciated capital goods. It is productive capital formation plus net additions to the stock of housing and the stock of inventories.


Rack unit

A rack unit (abbreviated U or RU) is a unit of measure defined as . It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed as multiples of rack units. For example, a typical full-size rack cage is 42U high, while equipment is typically 1U, 2U, 3U, or 4U high.
Definition.
The rack unit size is based on a standard rack specification as defined in EIA-310. The Eurocard specifies a standard rack unit as the unit of height; it also defines a similar unit, horizontal pitch (HP), used to measure the width of rack-mounted equipment. The standard was adopted worldwide as "IEC 60297 Mechanical structures for electronic equipment – Dimensions of mechanical structures of the series", and defines the sizes for rack, subrack (a shelf-like chassis in which cards can be inserted), and the pitch of printed circuit boards/cards providing physical compatibility of technological equipment, typically in telecommunications.
While a rack unit is defined as , a front panel or filler panel in a rack is not an exact multiple of this height. To allow space between adjacent rack-mounted components, a panel is inch  less in height than the full number of rack units would imply. Thus, a 1U front panel would be 1 inch  tall. If "n" is number of rack units, the ideal formula for panel height is for calculating in inches, and for calculating in millimetres. Manufacturing allows for dimensions with less precision.
The mounting-hole distance (as shown to the right) differs for 19-inch racks and 23-inch racks: The 19-inch racks uses uneven spacings (as shown to the right) while the 23-inch racks uses evenly spaced mounting holes. Although it is called a 19-inch rack unit, the actual mounting dimensions of a 19-inch rack unit are 18 inches  wide, center to center.
The 19-inch rack format with rack-units of was established as a standard by AT&T around 1922 in order to reduce the space required for repeater and termination equipment in a telephone company central office.
Configurations.
A typical full size rack is 42U, which means it holds just over of equipment, and a typical "half-height" rack is 18–22U, which is around high.
Whereas there is no formal specification for "half rack", the term "half-rack" can have different separate meanings: It can describe equipment that fits in a certain number of rack units, but occupy only "half the width" of a 19-inch rack . These are commonly used when a piece of equipment does not require full rack width, but may require more than 1U of height. For example, a "4U half-rack" DVCAM deck occupies 4U (7 in) height × 9.5 in width, and in theory, two 4U half-rack decks could be mounted side by side and occupy the 4U space. It can also describe a unit that is 1U high and "half the depth" of a 4-post rack (such as a network switch, router, KVM switch, or server), such that two units can be mounted in 1U of space (one mounted at the front of the rack and one at the rear). When used to describe the rack enclosure itself, the term "half-rack" typically means a rack enclosure that is "half the height" (22U tall). There is also a "half rack width" size being used in IT applications where a device conforms to a smaller than 9.5" width so that these "half rack width" appliances may be used in a chassis system that fits the traditional 19" rack space, but allows for these 8.4 inch wide "half rack width" appliances to be inserted and removed easily without tools or the need to remove adjacent hardware. This "half rack width" concept is popular in applications where IT equipment is being used by military who are unable to use traditional 1U full depth IT appliances due to their large size.
Rack units are universally the same, but the type of thread can vary depending on the rack. Mounting rails can be No. 10-32 tapped (Unified Thread Standard), No. 12-24 tapped, metric M6 threaded or universal square holes. Universal square holes are becoming the most common as these allow the insertion of replaceable cage nuts for the type of thread needed. This prevents stripping of the threading on the rails and allows for more flexibility.


Surface finishing

Surface finishing is a broad range of industrial processes that alter the surface of a manufactured item to achieve a certain property. Finishing processes may be employed to: improve appearance, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, chemical resistance, wear resistance, hardness, modify electrical conductivity, remove burrs and other surface flaws, and control the surface friction. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. An unfinished surface is often called "mill finish".
Surface finishing processes can be categorized by how they affect the workpiece:
Mechanical processes may also be categorized together because of similarities the final surface finish.
Mechanical finishing.
Mechanical finishing processes include:
The use of abrasives in metal polishing results in what is considered a "mechanical finish".
Metal finish designations.
Annealed and descaled after hot rolling, this finish is suitable for industrial applications requiring heat resistance and corrosion resistance, where smoothness of finish is unimportant, such as chemical tanks, aircraft heaters, steam turbine shrouds and piping.
Also known as grinding, roughing or rough grinding. These finishes are coarse in nature and usually are a preliminary finish applied before manufacturing. An example would be grinding gates off of castings, deburring or removing excess weld material. It is coarse in appearance and applied by using 36–100 grit abrasive.
When the finish is specified as #3, the material is polished to a uniform 60–80 grit.
Also known as brushed, directional or satin finish. A #4 architectural finish is characterized by fine polishing grit lines that are uniform and directional in appearance. It is produced by polishing the metal with a 120–180 grit belt or wheel finish and then softened with an 80–120 grit greaseless compound or a medium non woven abrasive belt or pad.
This finish is commonly used for the medical and food industry and almost exclusively used on stainless steel. This finish is much finer than a #4 architectural finish. This finish enhances the physical appearance of the metal as well as increases the sanitary benefits. One takes great care to remove any surface defects in the metal, like pits, that could allow bacteria to grow. A #4 dairy or sanitary finish is produced by polishing with a 180–240 grit belt or wheel finish softened with 120–240 grit greaseless compound or a fine non woven abrasive belt or pad.
Also known as a fine satin finish. This finish is produced by polishing with a 220–280 grit belt or wheel softened with a 220–230 greaseless compound or very fine non woven abrasive belt or pad. Polishing lines will be soft and less reflective than a #4 architectural finish.
A #7 finish is produced by polishing with a 280–320 belt or wheel and sisal buffing with a cut and color compound. This is a semi-bright finish that will still have some polishing lines but they will be very dull. Carbon steel and iron are commonly polished to a #7 finish before chrome plating. A #7 finish can be made bright by color buffing with coloring compound and a cotton buff. This is commonly applied to keep polishing costs down when a part needs to be shiny but not flawless.
Also known as a mirror finish. This finish is produced by polishing with at least a 320 grit belt or wheel finish. Care will be taken in making sure all surface defects are removed. The part is sisal buffed and then color buffed to achieve a mirror finish. The quality of this finish is dependent on the quality of the metal being polished. Some alloys of steel and aluminum cannot be brought to a mirror finish. Castings that have slag or pits will also be difficult, if not impossible, to polish to a #8.


Inventory control

Inventory control or stock control can be broadly defined as "the activity of checking a shop's stock". It is the process of ensuring that the right amount of supply is available within a business. However, a more focused definition takes into account the more science-based, methodical practice of not only verifying a business's inventory but also maximising the amount of profit from the least amount of inventory investment without affecting customer satisfaction. Other facets of inventory control include forecasting future demand, supply chain management, production control, financial flexibility, purchasing data, loss prevention and turnover, and customer satisfaction.
An extension of inventory control is the inventory control system. This may come in the form of a technological system and its programmed software used for managing various aspects of inventory problems, or it may refer to a methodology (which may include the use of technological barriers) for handling loss prevention in a business. The inventory control system allows for companies to assess their current state concerning assets, account balances, and financial reports.
Inventory control management.
An inventory control system is used to keep inventories in a desired state while continuing to adequately supply customers, and its success depends on maintaining clear records on a periodic or perpetual basis.
Inventory management software often plays an important role in the modern inventory control system, providing timely and accurate analytical, optimization, and forecasting techniques for complex inventory management problems. Typical features of this type of software include:
Through this functionality, a business may better detail what has sold, how quickly, and at what price, for example. Reports could be used to predict when to stock up on extra products around a holiday or to make decisions about special offers, discontinuing products, and so on.
Inventory control techniques often rely upon barcodes and radio-frequency identification (RFID) tags to provide automatic identification of inventory objects—including but not limited to merchandise, consumables, fixed assets, circulating tools, library books, and capital equipment—which in turn can be processed with inventory management software. A new trend in inventory management is to label inventory and assets with a QR Code, which can then be read with smart-phones to keep track of inventory count and movement. These new systems are especially useful for field service operations, where an employee needs to record inventory transaction or look up inventory stock in the field, away from the computers and hand-held scanners.
The control of inventory involves managing the physical quantities as well as the costing of the goods as it flows through the supply chain. In managing the cost prices of the goods throughout the supply chain, several costing methods are employed:
The calculation can be done for different periods. If the calculation is done on a monthly basis, then it is referred to the periodic method. In this method, the available stock is calculated by:
ADD Stock at beginning of period
ADD Stock purchased during the period
AVERAGE total cost by total qty to arrive at the Average Cost of Goods for the period.
This Average Cost Price is applied to all movements and adjustments in that period.
Ending stock in qty is arrived at by Applying all the changes in qty to the Available balance.
Multiplying the stock balance in qty by the Average cost gives the Stock cost at the end of the period.
Using the perpetual method, the calculation is done upon every purchase transaction.
Thus, the calculation is the same based on the periodic calculation whether by period (periodic) or by transaction (perpetual).
The only difference is the 'periodicity' or scope of the calculation.
In practice, the daily averaging has been used to closely approximate the perpetual method.
6. Bottle neck method (depends on proper planning support)
Advantages and disadvantages.
Inventory control systems have advantages and disadvantages, based on what style of system is being run. A purely periodic (physical) inventory control system takes "an actual physical count and valuation of all inventory on hand ... at the close of an accounting period," whereas a perpetual inventory control system takes an initial count of an entire inventory and then closely monitors any additions and deletions as they occur. Various advantages and disadvantages, in comparison, include:
Vs. inventory management.
While it is sometimes used interchangeably, inventory management and inventory control deal with different aspects of inventory.
Inventory management is a broader term pertaining to the regulation of all inventory aspects, from what is already present in the warehouse to how the inventory arrived and where the product's final destination will be. This management involves tracking field inventory throughout the supply chain, from sourcing to order fulfilment. It encompasses the entire process of procuring, storing, and profiting off merchandise or services.
Inventory control is the process of managing stock once it arrives at a warehouse, store or other storage location. It is solely concerned with regulating what is already present, and involves planning for sales and stock-outs, optimizing inventory for maximum benefit and preventing the pile-up of dead stock.
Business models.
Just-in-time inventory (JIT), vendor managed inventory (VMI) and customer managed inventory (CMI) are a few of the popular models being employed by organizations looking to have greater stock management control.
JIT is a model that attempts to replenish inventory for organizations when the inventory is required. The model attempts to avoid excess inventory and its associated costs. As a result, companies receive inventory only when the need for more stock is approaching.
VMI (vendor managed inventory) and (co-managed inventory) are two business models that adhere to the JIT inventory principles. VMI gives the vendor in a vendor/customer relationship the ability to monitor, plan and control inventory for their customers. Customers relinquish the order making responsibilities in exchange for timely inventory replenishment that increases organizational efficiency.
CMI allows the customer to order and control their inventory from their vendors/suppliers. Both VMI and CMI benefit the vendor as well as the customer. Vendors see a significant increase in sales due to increased inventory turns and cost savings realized by their customers, while customers realize similar benefits.


Capital good

The economic concept of a capital good (also called complex product systems (CoPS), and means of production) is as a "...series of heterogeneous commodities, each having specific technical characteristics ..." in the form of a durable good that is used in the production of goods or services. Capital goods are a particular form of economic good and are tangible property.
A society acquires capital goods by saving wealth that can be invested in the means of production. People use them to produce other goods or services within a certain period. Machinery, tools, buildings, computers, or other kinds of equipment that are involved in the production of other things for sale are capital goods. The owners of the capital good can be individuals, households, corporations, or governments. Any material used to produce capital goods is also considered a capital good.
Capital goods are one of the three types of producer goods, the other two being land and labour. The three are also known collectively as "primary factors of production". This classification originated during the classical economics period and has remained the dominant method for classification.
Many definitions and descriptions of capital goods production have been proposed in the literature. Capital goods are generally considered one-of-a-kind, capital intensive products that consist of many components. They are often used as manufacturing systems or services themselves. Examples include hand tools, machine tools, data centers, oil rigs, semiconductor fabrication plants, and wind turbines. Their production is often organized in projects, with several parties cooperating in networks (Hicks et al. 2000; Hicks and McGovern 2009; Hobday 1998).
A capital good lifecycle typically consists of tendering, engineering and procurement, manufacturing, commissioning, maintenance, and (sometimes) decommissioning.
Capital goods are a major factor in the process of technical innovation.
Capital goods are a constituent element of the stock of capital assets, or fixed capital and play a key role in the economic analysis of "... growth and production, as well as the distribution of income..."
Immaterial capital goods.
Capital goods can also be immaterial, when they take the form of intellectual property. Many production processes require the intellectual property to (legally) produce their products. Just like material capital goods, they can require substantial investment, and can also be subject to amortization, depreciation, and divestment.
Differences from consumer goods.
People buy capital goods to use as static resources to make other goods, whereas consumer goods are purchased to be consumed.
For example, an automobile is a consumer good when purchased as a private car.
Dump trucks used in manufacturing or construction are capital goods because companies use them to build things like roads, dams, buildings, and bridges.
In the same way, a chocolate bar is a consumer good, but the machines that produce the candy are capital goods.
Some capital goods can be used in both production of consumer goods or production goods, such as machinery for the production of dump trucks.
Consumption is the logical result of all economic activity, but the level of future consumption depends on the future capital stock, and this in turn depends on the current level of production in the capital-goods sector. Hence if there is a desire to increase consumption, the output of the capital goods should be maximized.
Importance.
Capital goods, often called complex products and systems (CoPS) (Gann and Salter 2000; Hobday 2000), play an important role in today's economy (Acha et al. 2004). Aside from allowing a business to create goods or provide services for consumers, capital goods are important in other ways. In an industry where production equipment and materials are quite expensive, they can be a high barrier to entry for new companies. If a new business cannot afford to purchase the machines it needs to create a product, for example, it may not be able to compete as effectively in the market. Such a company might turn to another business to supply its products, but this can be expensive as well. This means that, in industries where the means of production represent a large amount of a business's start-up costs, the number of companies competing in the market is often relatively small.
Investment required.
The acquisition of machinery and other expensive equipment often represents a significant investment for a company. When a business is struggling, it often puts off such purchases as long as possible, since it does not make sense to spend money on equipment if the company is not around to use it. Capital spending can be a sign that a manufacturer expects growth or at least a steady demand for its products, a potentially positive economic sign.
In most cases, capital goods require a substantial investment on behalf of the producer, and their purchase is usually referred to as a capital expense. These goods are important to businesses because they use these items to make functional goods for customers or to provide consumers with valuable services. As a result, they are sometimes referred to as producers' goods, production goods, or means of production.
In international trade.
In the theory of international trade, the causes and nature of the trade of capital goods receive little attention. Trade-in capital goods is a crucial part of the dynamic relationship between international trade and development. The production and trade of capital goods, as well as consumer goods, must be introduced to trade models, and the entire analysis integrated with domestic capital accumulation theory.
See also.
§ Listed in "The New Palgrave Dictionary of Economics"