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JULY 2022 I DESIGN007 MAGAZINE 61 is process plates a thin coat of nickel cov- ered by a thin layer of gold. e gold provides a very good solderable surface. When compo- nents are soldered onto these pads, the gold diffuses into the solder joint. e gold layer is very thin, so it won't reduce the solder joint strength. is process is generally not utilized for high reliability, long lifetime, or high vibra- tion applications. ENIPIG (Electroless Nickel, Immersion Palladium, Immersion Gold) ENIPIG is a three-layer metallic coating of 1.97 µin [0.05 µm] minimum, 2-5 µin [0.05 to 0.012 µm] typical, immersion deposited Au over 2 to 12 µin [0.05 to 0.30 µm] immersion deposited Pd over 118.1-236.2 µin [3 to 6 µm] electroless deposited nickel, per IPC-4556, nominal pad size of 0.060" x 0.060" (1.5 mm x 1.5 mm). ENIPIG is typically used for flat surface/ fine pitch devices. e benefits of ENIPIG are a long shelf life and environmental resistance, as well as low contact resistance and excellent solder joint with SAC solders. Understanding the cost drivers in PCB fab- rication and early engagement between the designer and the fabricator are crucial ele- ments that lead to cost-effective design suc- cess. Following your fabricator's DFM guide- lines is the first place to start. DESIGN007 Anaya Vardya is president and CEO of American Standard Circuits; co-author of The Printed Circuit Designer's Guide to… Fundamentals of RF/ Microwave PCBs and Flex and Rigid-Flex Fundamen- tals; and author of Thermal Management: A Fabricator's Perspective. Visit to download these and other educational titles. He also co-authored "Fundamentals of Printed Circuit Board Technologies" and provides a discussion of flex and rigid flex PCBs at RealTime with… American Standard Circuits. Supercomputers can crunch massive data sets and give us insights into the wonders of the universe. But a sub-penny microprocessor that flexes to fit on a beer bottle and tells you whether your brew is still cold? Creating that technology has been surprisingly more difficult to achieve. Recently, a team of researchers from the Uni- versity of Illinois Urbana-Champaign said: hold my beer. Working with British flexible electron- ics manufacturer PragmatIC Semiconductor, the researchers developed the first commercially viable flexible plastic microprocessor chips, called FlexiCores, that can be manufactured at scale for less than a penny per unit. The new processors could help even every- day objects become "smart." "For example, you could put processors on bandages to detect whether a wound is heal- ing, or add them to consumer goods packag- ing to track progress along the supply chain," said Rakesh Kumar, a professor of electrical and computer engineering and researcher in the Coordinated Science Lab at UIUC. "The chal- lenge has been creating a processor that can be both cheaply produced and flexible enough to fit snugly even against uneven surfaces on our body, packages, or beer bottles." The low gate-count in FlexiCores improves yield and reduces the bill of materials—the amount of material needed to produce each chip. "These chips combine the flexibility and cost benefits of plastic technology with the high yield and low bill of materials enabled by our architec- ture," he said. "It will be interesting to see where we go from here." (Source: University of Illinois) University of Illinois Researchers Create Low-cost, High-yield Plastic Microprocessors

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