I remember an incident with silkscreen under a component where the component
did a see-saw on the silkscreen. Not good at all. Sorry I don't have
pictures or white paper to back this up.

Allen Maddox
Sr. PC Board Designer
GAI-Tronics, Corporation
PO Box 1060
Reading, PA 19607-1060

voice: 610-796-5854
FAX: 610-777-1870

[log in to unmask]

www.gai-tronics.com


-----Original Message-----
From: Steve Thomas [mailto:[log in to unmask]]
Sent: Wednesday, July 31, 2002 12:16 PM
Subject: silkscreen as solder dam?


Greetings...

Our overseas assembler wants us to add a line of silkscreen between pads on
bottom-side 0603 R's and C's,
apparently as a solder dam to reduce bridging in wave solder.  There already
is mask between pads, so this seems
a bit out of the ordinary (we do very little two-sided assembly here but I
have never seen bridging on chips).

Has anyone ever seen this done?  Does this sound like a design band-aid to
fix a process problem (talk about the flip side of
a coin!)?  How do you attribute a bridge underneath a glued-on part to wave
solder?  I don't have the benefit of a thorough
knowledge of their process, but I'm speculating they may be printing their
glue with a squeegee contaminated with solder paste.

Your thoughts?

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