RE>ASSY: PQFP pull test                      12/13/96

William,
I seem to remember that for 25 mil pitch PQFPs, we were getting about 1-2
pounds, and for 50 mil pitch devices about 3-6 pounds.  I seem to remember
them as "typical".

In my opinion, you start to run into problems when you try to classify them
as "good" or "bad" without comparing them to a baseline.  I don't believe
that you can use this kind of test as a means of predicting reliability,
although I realize that others don't share this view.  I believe that this
test is helpful as a process development or process control tool.  This is
where the baseline comes in.  

This leads to the second part of your question.  It's vital that your test
method be consistent to obtain valid data.  You should be careful with
package excision (be careful not to disturb the solder joints - we found that
either a slow speed, oil-cooled diamond saw or a laser worked well), lead
clamping method, angle of pull (we opted for 90 degrees, and this was kept
constant throughout the test), and crosshead speed (we opted for 0.2
inch/minute).

Good luck!

Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
[log in to unmask]

--------------------------------------
Date: 12/11/96 7:17 PM
To: Greg Bartlett
From: William Hart/HNS
What should be typical pull test results on PQFP leads (160 pin).
Good?
Marginal?
Bad?

How does one do this test (where do you pull, & at what angle to the lead do 
you pull, etc)?



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