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78 SMT Magazine • February 2014 to figure out that a highly integrated or what used to be called VLSI (very large scale integra- tion) chip like an FPGA could conceivably be at the root of a high-speed PCB manufacturing issue. Think about it. Today's chip geometries are around 32 nm and continually getting smaller. Those extremely fine geometries are crucial to pack more metal-oxide semiconductor field- effect transistors (MOSFETs) onto the silicon so that millions and millions of those transistors or active devices provide the necessary electronics functions or gates to achieve high performance. High performance means higher speeds, and that's the name of the game. That's what OEMs demand. It doesn't matter if you're an industrial, consumer, mil/aero, or computer OEM. You need high performance to meet cus- tomer requirements. Meanwhile, at the chip level, those millions of electronic gates in an FPGA generate lots of heat. The more power generated in the newer, higher-speed FPGAs, the higher the heat that is generated inside that chip. That heat must get out or dissipate. If not, it may cause an FPGA or any other semiconductor chip to prematurely fail, or at the minimum, cause signal disrup- tions and lower, poorer performance. That's one side of the story. The other deals with the fact FPGAs and other highly advanced system-on-chip (SoC) devices are today mostly outsourced for fabrication. Chipmaker-owned fabs are history, and independent chip fabrica- tors have emerged in the last decade or so to take care of the chip making. Consequently, a gap exists wherein R&D—once prominent in the chipmaker's house—is now questionable, leaving reliability doubtful. Also, it looks to me that when it comes to testing, verification, and validation, these com- panies are not putting in as much time, energy, and resources to assure ICs and FPGAs can truly be tested at high-speed levels. When high-speed devices like FPGAs are subjected to stringent testing and they are put on carefully designed boards, they can undergo assembly and pass high-speed test levels. I highly respect FPGA and other chipmak- ers because today they face major design and fabrication challenges as Moore's Law contin- ues to drive newer chip generations. However, it might be a good time in our industries—EMS and semiconductor—to bring our mutual issues to the table and find ways to closely work to- gether to minimize or avoid issues brought on by advanced technologies. On the other hand, avoiding these issues, even when brought to the FPGA vendor's atten- tion, is a clear and blatant disservice to both the EMS provider and OEM. In some cases, even bringing problems to the FPGA vendor's atten- tion may be all for naught; in some cases, they don't have the necessary validation knowledge or data necessary to determine the root cause. Technology moves so fast it is difficult or near impossible to harness that level of detail and retain it. What is an eMS provider to do? Primarily, a high-speed PCB is subjected to all the key test and verification steps at assem- bly and test. A reputable and experienced EMS provider goes even further to apply innovative methods to uncover elusive problems. Howev- er, if components like an FPGA are suspected to be the problem, the EMS provider has to be diligent and contact the component manufac- turer to get to the root of a problem. Simul- taneously, the EMS provider makes certain the OEM is fully aware of these component suspi- cions. In the case of a questionable FPGA, it's in the best interest of the OEM to assure it is tested at their facilities at extremely high speeds at dif- ferent permutations, combinations of different voltages, and different temperature settings, vi- brations, cycling, and zoning to ensure that all faults relating to that FPGA are found during the OEM's testing, validation, and debugging phase. By doing so, that same FPGA doesn't have to go through the EMS cycle to locate those errors. SMT Zulki Khan is the founder and president of Nexlogic Technologies Inc. To read past columns, or to contact the author, click here. ZUlKI'S PCb NUggETS uNCOVerING aSSeMbLy PrObLeMS OF HIGH-SPeeD PCbS continues

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