> Date: Sat, 7 Feb 1998 10:33:31 -0600 > From: Calvin > Subject: Re: ??? high temperature PIC ??? > I used to work at a semiconductor factory, and I can tell you that most (if > not all) semiconductors, from a simple diode up to a microprocessor are > extensively tested during most phases of manufacturing. In this way, by > rejecting bad units in early stages of manufacture materials and work is > saved. What good would it be to assemble a bad chip and at the end of the > process find out it is bad? > And failure rates are usually measured in ppms (parts per million). In the > plant I worked a goal was 100ppm, and we were actually doing about > 180-250ppms. > > > Gabriel > TGO > > -----Original Message----- > > >Wow! I never expected that the manufacturing process for each individual > >chip involved so much testing! Is this, then, a major or maybe THE major > >share of the price of the IC? It would seem to me to be a fairly expensive > >undertaking. Also, in a typical consumer electronic device (take a > >microwave oven, TV, or clock, for example), is the initial failure rate > >less than 99.99% ??! Again, this is news to me. As a first year EE student > >and an avid electronics hobbyist, I have never had any of my designs go > >into production, but have considered trying several times. I guess that > >this is the reason why I am unfamiliar with the expectations of > >manufactured devices. It just seems that in my experience, I have seen at > >least several of the applicances which I have purchased fail prematurely or > >never work. If the rate were really 99.99%, I must be very unlucky. Then > >again, we engineers are especially cursed by murphy, right :) > > >>Sean I can well understand and believe that a Semiconducter manufacturing plant will test its products so extensively. However, that is not neccesarily the case with manufacturs of electronics goods. Not too long ago I attended a seminar by an expert speaker from leading test equipment manufacturer HP who told us that the world trend with manufacturers of consumer electronic goods is more and more to shy away from any system testing at all! Basically what he said is that if you control your manufacturing processes carefully, then it should not be neccessary to test at all. The policy is "let the customer test it for you, and if he complains then you just replace it". So it is very likely that the failure rate of new goods could be much worse than 99.99%. Obviously the same theory off non-testing does not apply to military, medical, avionics or other critical electronic goods. Werner -- Werner Terreblanche http://users.iafrica.com/w/we/wernerte/index.htm wterreb@plessey.co.za (work) OR wernerte@iafrica.com (home) Plessey SA, PO Box 30451,Tokai 7966, Cape Town, South Africa or at home : Suite 251, PostNet X5061, Stellenbosch, 7599 Tel +27 21 7102251 Fax +27 21 7102886 Home +27 21 8523249 ------------------------------------------------------------