Hello,

A couple of thoughts relative to soldering to gold. You stated the old
boards were scrubbed to make them look better. This definitely removed some
of the gold and reduced the gold thickness.

The newer boards may have thicker gold plating due to the no scrubbing
process. Depending upon the thickness of the gold plate this could have an
impact on the appearance of the solder joint. It could look dull and grainy
due to the dissolution of gold in the molten solder.

Have the customer defined the gold thickness on the boards. Get some
statistics on the solder deposition process as to the average thickness of
paste being applied and find out if they changed the solder paste at any
time between the two dates mentioned.


Lots of variables, start with a few and work your way through them to
eliminate some of them to find the causal element of the problem.

Leo Lambert
EPTAC Corp.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Russell Burdick
Sent: Thursday, November 14, 2002 8:04 PM
To: [log in to unmask]
Subject: [TN] gold solderaility


Hello everyone!

I could use some help concerning soldering to gold.

Problem:
A customer of ours has given feedback to our salespeople that hard gold
boards we made in May 2002 were much better to solder to than what we sent
in October 2002. Biggest difference was stated as the newest boards have
fiducials that auto pick and place equipment can't read because under the
lights they look "black". Under normal shop lights both boards look bright
and shiney(sp?).

Also, the customer commented that on the boards with "black" unreadable
fiducials had solderjoints that looked very dull.

Known manufacturing/processing differences between months of May and October
(aka, confessions of a process engineer):
Prior to August 2002, dull plated gold boards were scrubbed to improve
appearances. After August 2002 no scrubbing needed when a carbon treat and
proper wetters were performed/maintained in nickel and gold baths.


Any and all comments are greatly appreciated.





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