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46 The PCB Magazine • October 2015 hours it that a sequential lamination approach would have taken. Optimizing cycle time eliminates bottle- necks and provides the added benefit of im- proving equipment utilization and thus the businesses' profitability and the ROI for any capital equipment investments. Materials Materials also play an important part in cy- cle time. One trend that is happening in 2015 is that many shops have balanced their process during the last few years around common lead- free epoxy press cycle conditions (for which a typical press cycle may run at 360°F for 70 minutes under 250 psi). However, according to some fabricators, more and more jobs are com- ing in asking for low-loss, high-speed digital (HSD) materials (the most popular of which can require temperatures up to 385°F for 120 minutes and pressures as high as 580 psi). As a result, fabricators are finding that their lamina- tion cycle time has become a throughput con- straint as their work mix changes. This is good news for people selling lamination presses and also creates opportunity for some next genera- tion materials that will have comparable electri- cal properties to the current HSD offerings but process under conditions closer to lead-free ep- oxies. Of course, even the highest velocity, and most finely balanced operation does not help if you have to restart a job because it fails at final testing. Controls in your process, the quality of the materials you use, and training of your peo- ple are fundamental requirements, critical to your differentiated value proposition. The pay- off of course is that a quick-turn premium can fetch 200% or more of the price of a standard lead time for the same board. PCB THE ECONOMICS OF REDUCING CyCLE TIME IN PCB FABRICATION Jason Marsh is vice president of product management at insulectro. a detailed nano-mechanical study of mechani- cal degradation processes in silicon structures con- taining varying levels of lithium ions offers good news for researchers attempting to develop reli- able next-generation rechargeable batteries using silicon-based electrodes. anodes—the negative electrodes—based on silicon can theoretically store up to ten times more lithium ions than conventional graphite electrodes, making the material attractive for use in high-performance lithium-ion batteries. how - ever, the brittleness of the material has discouraged efforts to use pure silicon in battery anodes, which must with- stand dramatic volume changes during charge and discharge cycles. using a combination of experimen- tal and simulation techniques, research- ers from the georgia institute of Technology and three other research organizations have reported surprisingly high damage tolerance in electro- chemically-lithiated silicon materials. The work suggests that all-silicon anodes may be commer- cially viable if battery charge levels are kept high enough to maintain the material in its ductile state. "Silicon has a very high theoretical capacity, but because of the perceived mechanical issues, people have been frustrated about using it in next- generation batteries," said Shuman xia, an assis- tant professor in the george W. Woodruff School of mechanical Engineering at georgia Tech. "But our research shows that lithiated silicon is not as brittle as we may have thought. if we work care- fully with the operational window and depth of discharge, our results suggest we can potentially design very durable silicon- based batteries." Supported by the national Science Foundation, the research was reported September 24 in the journal nature communications. New Assessment of Silicon for Next-gen Batteries puTTing iT All TogeTher

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