** High Priority **


We use SPC on all critical parameters (of course) but also use a C-Chart for total defects in 10 panels every 1/2
hour.  This gives us a realtime indication of something going wrong.  It reduces rework and forces the inspection
personnel to communicate problems to the area causing them.  Sometimes we hear complaints about doing it but
many times it has kept us from building a lot of product with problems.   

Brian Wilkinson
TRW/AEN




>>> Kenny Bloomquist <[log in to unmask]> 10/31/96 11:00pm >>>
We are trying to do SPC on our wave soldering process.  It seems that everyone in our company has their own
opinion as to what should be tracked.

I would like to hear from anyone who is successfully, (or unsuccessfully), using SPC on their wave solder
process and what it is that you are measuring.  Some suggestions from our SPC group are as follows:

Prevention:  What do others "look at" and why?  Solder density, wave height, various temperatures, angles, rates,
etc.  How much impact does board configuration have?  Tightly packed and complex or loose and simple? 

Failure:  What is a good measure of defects?  Defects per solder joint, per hole, top and bottom, per board, per
square inch, per component, per run, per day, per XX minutes of run time, per ??

What questions should we be asking?  We still have boards that require touch-up after wave solder, is there
anyone who has eliminated that need in the DOD and space application world?

Thanks in advance to all that respond.

Ken Bloomquist
Sr. Staff Process Eng.


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