I have built boards with silkscreen between chip component pads and had
problems with glue adhesion.  The smt adhesive would peel the silkscreen off
the soldermask.  Now when I see this in design I ask to have it removed.

Brad Vanderhoof

-----Original Message-----
From: Steve Thomas [mailto:[log in to unmask]]
Sent: Wednesday, July 31, 2002 9:16 AM
To: [log in to unmask]
Subject: [TN] 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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