PCB007 Magazine

PCB007-Nov2018

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NOVEMBER 2018 I PCB007 MAGAZINE 65 Some scientists at RESRI and IMS in Europe were looking at what was going on with the ra- diation effects in COTS integrated circuits. For a long time, that wasn't that big of a deal because most applications are terrestrial rather than up in the air. We have the atmosphere protecting us, and in this particular presentation, what the folks from Europe showed was an aircraft was transiting the South Atlantic Anomaly. The South Atlantic Anomaly is an area on the earth's surface where the level of cosmic radiation is quite a bit higher, and it has to do with how the Van Allen belt twists. The Van Allen belt is this ionizing belt that shields and screens earth from cosmic radiation. There's a small twist to the belt, and the South Atlantic just off the coast of Brazil has a much higher total of ionizing radiation nodes than any place else on the surface of the planet. There was an airplane that was transiting through that area, and there was a disruption in the flight control system; thankfully, they were able to recover, and the only thing that happened was some overhead bins popped. This is another area that people are becoming increasingly con- cerned about. As those geometries in proces- sors and memories shrink, they become more susceptible to those single events. Happy Holden: I'm surprised with the num- ber of Army, Navy, and military contractors that have shown up at our meetings, includ- ing SpaceX and a few others, that are having failures and aren't sure what's caused them. That's why we're having this workshop to- day. Has anybody contacted you on the fail- ure problem we're having with microvias and stacked vias? Brown: Our Sherlock software does an excellent job of modeling those properties of the micro- vias. What we're seeing both in reliability fail- ure analyses and cross-sectioning after failure is if the construction of the microvia configu- ration is done correctly, those microvia feed- throughs can actually be more reliable than a plated via for plated through-holes. Holden: That's what we expect, but we're not getting that.

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