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February 1998

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Subject:
From:
John Maxwell <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 9 Feb 1998 08:50:18 -0700
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>Dear Technetters,
>
>I have seen the most weird problem in my 7 years in PCBA manufacturing
>environment. Solder is getting between the epoxy and component and/or
>between fab and epoxy thus shorting it out across terminations of SMT caps.
>
>Does any one has seen similar problem? Any resolution? Our regular process
>is epoxy application thr' stencil, component loading, curing and then hand
>load & wave.
>
>Any help or leads will be highly appreciated.
>
>re,
>ken patel

Ken,
Check moisture absorption of the PWB to see if it is out gassing during
cure causing bubbled to form underneath the chip. Also check the cure
schedule to insure that it does not exceed the maximum temperature. Some
materials can out gass under excess cure conditions.

John Maxwell

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