🚀 go-pugleaf

In article <C0Cos2.2Fw@usenet.ucs.indiana.edu>, ntaib@silver.ucs.indiana.edu (Iskandar Taib) writes:
|> Well, the way I look at it is what is the opportunity cost of not
|> testing a 33MHz failure at 25 MHz? You could 1) throw it away or
|> 2) test it at 25 MHz and sell it if it passes. 
|> 
|> Its a matter of which would be cheaper: to make another 25 MHz chip
|> from scratch _and_ test it or to test the reject. Testing the reject 
|> is cheaper, usually, depending on how many of the 33 MHz failures 
|> would pass at 25 MHz. 
|> 
Don't think in terms of 2 distinct stages of testing - at 33MHz and at
25MHz. It is all one stage.   Depending on the test, it could be a
single test that grades accoringly.
 
For example lets take a simple switching speed from low to high.  If
it takes 35ns to switch (low and high voltage levels reference points
differs in low->high and high->low), then it will fall into the 25MHz
grade.  But if the switching takes only 28MHz then it will fall into
the 33MHz grade.
 
In the actual case, the testing is a lot more complex and there are
hundreds of electrical tests before the chips a graded.

............................................................................
. Kyle Hor                    .    /       / _   .  Email  khor@bnr.ca     .
. Bell-Northern Research Ltd. .   /__\  / / /_\  .  Phone  (613) 763-2488  .
. Ottawa, Ontario, Canada     .  / \  \/ /  \__  .  ESN          393-2488  .
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................  standard disclaimer, 2 cents opinion  ....................
.............  searching forever, for the perfect solution  ................