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February 2009

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Subject:
From:
Louis Hart <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Louis Hart <[log in to unmask]>
Date:
Thu, 19 Feb 2009 11:23:21 -0500
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TechNetters, would someone fluent in soldering and terminology please advise or comment? In the IPC T-50H definition of dewetting, there is mention of a 'thin coating of solder' on the base metal. Pictures of dewetting in A-600 appear to show exposed base metal. A customer is complaining about dewetting on some PCBs that have all surfaces covered with solder, thin in some regions, thick in others. I can't see clearly the contact angle between the thick solder and thinner areas, but it may not be much different from 90 degrees. To me, it appears solderability should be OK, but I want to understand the dewetting phenomenon better before discussing with the customer.

By what physical mechanism does dewetting occur? How does this mechanism differ from nonwetting?

Thanks for any guidance...Louis

Louis Hart
Compunetics
Monroeville, PA
USA
[log in to unmask]<mailto:[log in to unmask]>
412-858-1272


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