🚀 go-pugleaf

In article <C0CoGq.1ww@usenet.ucs.indiana.edu>, ntaib@silver.ucs.indiana.edu (Iskandar Taib) writes:
|> In article <1992Dec30.233238.14371@ptdcs2.intel.com> ssivakum@ptdcs2.intel.com (Sam Sivakumar) writes:
|> 
|> >    I work in lithography R&D, so I am not intimately familiar with the
|> >sort and test world, but I know that every chip sold is tested.  Usually,
|> >once the lot of wafers leaves the fabrication line, every chip on each wafer
|> >is tested for functionality as function of voltage and speed.  There may be
|> >other tests done at this stage as well, like transistor characteristics, etc.
|> >and maybe others that I am not aware of.  All chips that do not work are
|> >inked, so when the wafer is diced into individual chips, the inked fellas are
|> >rejected summarily.
|> 
I agree 100%.  This is how it is done.  BTW, there are 3 main
category of tests for digital ICs.
 
  functional  : mainly boolean logics
  DC          : voltage & current levels
  AC          : switching speed

At the wafer stage, only simple functional tests are performed as the DC and AC
characteristics could change due to the processes further down the line.

|> Hmmm
|> 
|> Anyone know where one could write to get rejects like this? 'Twould 
|> be a nice conversation piece... 
|> 
|> Perhaps they wouldn't give away the latest 486-66/DX2 but surely there 
|> are old 286 wafers lying around somewhere..
|> 
I dunno what they do with the wafers, but they are unsightly.  Good dice
are taken out to be assembled as IC's and the remaining bad dice scattered
across the wafer are all inked anyway.

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