Q. How do you maintain high yields on an IC production line.

A. When too many parts fall outside spec., change the spec.


We recently had a production line problem with Matra Harris 2Kx8 35nS 
parts. The cause was Address Hold From End Of Write, specified at 
0nS. We had one part that needed 6nS before it would work. Most parts 
needed 2-3nS.
After checking several data books we found that the 1987 data sheet 
specified 0nS for this parameter, the 1989 data sheet specified 5nS 
for this parameter, and the 1990 data sheet specified 2nS for this 
parameter. Not fair I say. Be forewarned.

Matra were called in and so far have agreed to accept the parts back.
The specification discrepency was not discovered until after they left.
While they were here they claimed that their part was compatible with 
Cypress parts. The Cypress part specifies 0nS for this parameter. 
The also suggested that since we have been using this part for 
several years without problem that this must be just chance error. 
What garbage ! 

I will be recommending disqualifying them for this part, (after they
supply enough good parts go keep production going) and putting them 
on restricted approval as a company for any part.