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From: Diehl, Nancy
To: Yuen, Mike
Subject: Alphametals Ionograph 500 M Test
Date: Thursday, May 23, 1996 10:30AM

In the past we have operated the Ionograph tester in manual mode for 10 
minutes with an accept/reject criteria of 20 ugNaCl/sq.in..  However, we 
discovered that this is not the proper method, that in fact, it should be 
operated in automatic mode.  The problem with automatic mode is many tests 
run for 20 to 60 minutes before detecting a levelling off of contamination. 
 I have studied many test files and find a significant correlation between 
the contamination measured at 10 min. vs. the final contamination.

With a high degree of confidence, if the contamination level is less than 
8.5 ugNaCl/sq.in. within the first 10 min. the raw PCB will meet the accept 
criteria.  I would like the ability to run the equipment in auto mode, 
observe the contamination level at the 10 min. mark, if less than 8.5 then 
shut the test down, yet still retain the test record.  I am told this is not 
possible.  Is there a solution to this?  Can the software be changed to 
allow for retention of tests terminated prior to the equipment auto mode 
shutdown?

One recommendation I received was to run in manual mode for 10 min..  If the 
contamination level is above 8.5, pull a second sample and run in auto mode. 
 This is an unacceptable alternative because 55% of the tests run in 
automode shut off by 2 minutes.  In manual mode it would run the full 10 
minutes and not shutdown prior if a levelling off was determined.  So on one 
hand I am eliminating the long 20-60 minute auto mode tests, but on the 
other hand running 55% of the tests 8 minutes longer than necessary.

Anyone with answers or suggestions please contact me via e-mail at:
[log in to unmask] or by phone at (414)751-3573.
Thank you.
Nancy Diehl.