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A series of experiments test the well-known area ratio rule.

A stencil aperture’s area ratio (AR) is a simple calculation that divides the area of the aperture opening by the area of its wall. It was derived in the 1990s and compares the adhesive forces of the solder paste deposit on the PCB pad with the adhesive forces of the solder paste on the stencil walls. For the material to transfer efficiently, the forces holding it to the pad must overcome the forces holding it to the aperture walls. Therefore, calculating the relative areas represents the relative adhesive forces affecting solder paste release.

The amount of solder paste released from an aperture is referred to as transfer efficiency (TE) and expressed as a percent of total aperture volume. Stencil or solder paste release characteristics are often illustrated by plotting TE against AR.

AR guidelines were originally set at 0.66 as a minimum to ensure good (>80%) TE. Many of these original guidelines have been relaxed due to improvements in solder paste, stencil materials and nanocoatings. With good materials, equipment and tooling, and robust printing practices, apertures with ARs as low as 0.50 can often be printed in production on 4-mil thick stencil foils with excellent results.

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Updates in silicon and electronics technology.

Ed.: This is a special feature courtesy of Binghamton University.

Next-gen chips will be powered from below. As transistors continue to be made thinner, the interconnects that supply them with current must be packed closer, which increases resistance and power. In processors, both signals and power reach the silicon from above. Arm researchers have developed a technology that separates those functions, saving power and making more room for signal routes. The signals travel along the copper traces of a PCB into a package that holds the SoC, through the solder balls that connect the chip to the package, and then via on-chip interconnects to the transistors. These interconnects are formed in layers called a stack. It can take a 10- to 20-layer stack to deliver power and data to the billions of transistors on today’s chips. (IEEC file #12450, IEEE Spectrum, 9/2/21)

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Using liquid metal to turn motion into electricity, even underwater. North Carolina State University researchers have created a soft, stretchable device that converts movement into electricity and works in dry and wet environments. The heart of this energy harvester is a liquid metal alloy of gallium and indium. The alloy is encased in a hydrogel with the water containing dissolved salts (ions). The ions assemble at the surface of the metal, which induces a charge in the metal. Increasing the area of the metal provides more surface to attract a charge. This generates electricity, which is captured by a wire attached to the device. Researchers found that deforming the device by only a few millimeters generates a power density of approximately 0.5 mW/m-2, comparable to popular classes of energy harvesting technologies. (IEEC file #12449, Science Daily, 8/28/21)

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Does sustained ISO 9001 and Lean Six Sigma deliver success?

Sustaining quality management systems and continuous improvement strategies is critical for retaining a competitive advantage in the printed circuit board industry. Implementing and sustaining both ISO 9001 and Lean Six Sigma provides quality improvements, enhances organizational performance, creates efficiencies, increases market share, improves financial performance, and reduces product reliability risk. This quantitative correlational study evaluates critical success factors for implementing and sustaining ISO 9001 and Lean Six Sigma. Survey data were collected from the North American printed circuit board (PCB) industry. Canonical correlations were used for data analysis. A statistical correlation was found between critical success factors for implementing and sustaining ISO 9001 and Lean Six Sigma. Three canonical variates were extracted and interpreted.

Quality has become a key process indicator for manufacturing and service companies. Quality is a strategic priority for all modern businesses.1 Improving and sustaining quality is a critical organizational strategy to retain customers in today’s globally competitive environment. Quality management is used to proactively find solutions to current and future cost and risk problems.

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An interview with Colombia’s largest EMS company.

Colombia is the 28th largest country by population and the 38th largest by nominal GDP. Residing as South America’s connection into Central America, it is in the same time zone as the Eastern US during daylight saving time.

Invertronica was founded in early 2003 in Colombia and includes several companies involved in the design, prototyping and manufacturing of electronics products. Those companies include Tecrea, an electronics design and engineering unit; LosComponentes.com.co, a parts distributor, and Colcircuitos, the largest EMS company in Colombia. It can move fast: 24 hours from design to assembly.

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A look back at friends and colleagues who left us in 2021.

Isamu Akasaki

Semi genius - Akasaki

Isamu Akasaki, 92, Japanese physicist invented the first efficient blue LED and shared the 2014 Nobel Prize in physics.

Robert “Bobby” Baker, 60, Sanmina/SCI senior buyer.

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A new study reveals emerging applications for attaching very-fine-pitch parts using low-temp methods.

Electrically conductive adhesives (ECAs) have been touted for decades as a potential replacement for solder. Technology roadmaps by organizations ranging from IPC to the Surface Mount Council often listed ECAs as a “coming” technology, and scores of papers have been presented highlighting possible uses and likely end-products.

In early October, the international research firm IDTechEx released a new study called “Electrically Conductive Adhesives 2022-2032: Technologies, Markets, and Forecasts.” Matthew Dyson, Ph.D., a senior technology analyst at IDTechEx specializing in printed, organic and flexible electronics, spoke with Mike Buetow about the study’s findings.

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