Stephen,

This sounds like the old style of solder mask (SR1000 was one trade name)
that was applied over reflowed solder.  When run through wave solder the
reflow melts and more solder slips under the mask from each of the component
holes in the mask giving it that wrinkled look.

Most boards are now built with solder mask over bare copper (SMOBC) and then
put through hot air solder leveling (HASL) to "tin" plate all the solder
joints.

I'd check with the board vendor to find out what process he is running.  The
SR1000 mask was cheaper and was fine for hand soldering, but with the advent
of wave soldering SMOBC and HASL is the setup of choice.

Regards,

Phil Nutting
Manufacturing Engineer
Kaiser Systems, Inc.
High Voltage Power Supplies That Work(tm)
126 Sohier Road
Beverly, MA 01915
ph: 978-922-9300
fx: 978-922-8374
[log in to unmask]

-----Original Message-----
From: Stephen Thornton [mailto:[log in to unmask]]
Sent: Monday, November 20, 2000 10:23 PM
To: [log in to unmask]
Subject: [TN] Help Solder mask wrinkled


We have a bunch of boards where after wave soldering the solder mask is
wrinkled.
We have quaratined the remaining bare PCB's but really need to use the ones
that are wrinkled.
We have performed the IPC test using adhesive tape and the mask does peel
off.
My question to the technet guru's is,  What can we do to these boards so
that we can use them?
We varnish coat all the boards- will this provide enough protection, what
about if we double coat them?
Any suggestions or helpfull hints would be greatly appreciated
Thanks
Stephen Thornton
Engineering Manager Tytronics
12 Circuit Drive Hendon SA 5014
Telephone: +61 (0)8 8268 5400
Fax: +61 (0)8 8268 2503

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