Steve, I've enjoyed reading your past answers and questions on the
     technet. You do have a way with words. Anyhow getting to the point.
     I've read most of the answers to your question and agree with most. I
     only have one question about the vibration test(my turn to sound
     ignorant:)). How much does the device weigh and how much stress is it
     putting on the joints? I know, thats 2 questions. Could it be that
     even with good fabrication you'll be going to failure?
            I'm not trying to cover your fabricator it definitely sounds
     like there some problems with the plating process. Your soldering must
     be good though. Anyway just my two cents.

     Mike Doty
     Hadco TCE


______________________________ Reply Separator _________________________________
Subject: [TN] Two distinct layers of copper...
Author:  "Stephen R. Gregory" <[log in to unmask]> at smtplink-hadco
Date:    10/6/99 3:57 PM


Hi ya'll!

Here's something weird I've never come across, but maybe some of you have. We
built this Hi-Rel board here that the PCB drawing calls out for 2-ounce
copper.

The board has this leaded SMT multi-capacitor part (it's like 3 huge ceramic
capacitors stacked on top of each other) and has 8-leads. After assembly, and
before we test then conformal coat it, we put the assembly on this vibration
table to go through some ESS.

There's been a few of these capacitor deals come loose because they're so top
heavy, but that's a whole 'nuther issue...

What we've been seeing on some of these boards, is that either the pad
completely lets go from the laminate (it's a polyimide), or sometimes we'll
see the pad come up in what looks like a layer of copper, yet there's still
copper down on the PCB...as if the copper has split horizontally in two
distinct layers? Is this possible? Does 2-ounce copper clad laminate get the
copper plated an ounce at a time? Is this a defect? I've never seen something
like this before, and I can take a picture and send it to ya' if you want me
to....

Thanks!

-Steve Gregory-

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