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42 PCB007 MAGAZINE I JULY 2019 It's Friday afternoon, and the shipping dead- line is approaching rapidly. Your high-visibili- ty Class 3, Level C product is just about done with electrical test and should fly through FA and barely make it. You are relieved and look forward to Saturday on the lake. Just to make sure, you call the ET department and check on the yield. The lead in ET replies, "96% fi- nal." You are quite happy with the news as you manufactured enough overage to compensate for that loss of 4%. Relieved, you head out the door pleased that the new customer delivery has been met. Not so fast! Your cellphone rings just as you press the disarm button on your getaway car, and your quality manager is on the other end. They say, "We have a problem." You happily retort, "We had a 96% yield! They passed ET!" But your quality manager replies, "You better come to the lab," and you have the same feeling as when the dealer flips a blackjack just when you've doubled-down. Their final comment be - fore hanging up is, "We better not ship this or- der." Feeling your boat sink before you even get it off the trailer, you reluctantly head to the lab. So, what happened? Although you had a 96% yield, it has been discovered that, within that 4% of failures, is a defect that puts the en- tire order at risk. In this case, I'm talking about barrel voids. ET had detected barrel voids in the 4% of failures. The decision now must be made as to whether the "passed" product can ship as reliable or should the order hold for evaluation. Looking from the outside, the an- swer is fairly clear that it should hold to evalu- ate the type of void detected and whether it poses a potential field failure once it leaves the manufacturing facility. This decision, however, is critical, and honestly, there are many times the order doesn't go on hold and ships instead. What Do You Mean "Passed" Isn't Enough? Testing Todd by Todd Kolmodin, GARDIEN SERVICES USA

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