Careful Doug...nowhere does the spec indicate trimmed leads must be covered
with solder. An example, how would YOU explain the acceptability of an
exposed vertical trace on a board that has been SnPb plated and fused?
Rick

-----Original Message-----
From: Douglas Pauls [mailto:[log in to unmask]]
Sent: Monday, January 29, 2001 7:01 AM
To: [log in to unmask]
Subject: Re: [TN] fractured joints


The IPC standard states that all clipped leads must either be  reflowed or
checked under 10X magnification. Is this just a standard for single  sided
boards? If you have a double sided board and a good fillet on the
component side of the board and you clipped the leads on the solder side
what  would be the cause of concern if a joint is fractured on the solder
side?

*One of the reasons that the specifications want you to check the clipped
leads, or better yet, reflow the solder to cover the clipped lead is so
that you cover the exposed metal of the lead which may corrode.  I have
seen many cases where a ferrous core of the lead is exposed by the clipping
process, which then corrodes in service.  If that exposed metal was covered
with tin-lead, that corrosion does not occur.

Not quite what you were looking for, but something to think about.

Doug Pauls
Rockwell Collins


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