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December 1997

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Thu, 4 Dec 1997 10:32:07 -0600
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Charles Barker@I-O INC
12/04/97 10:32 AM

Steve,

We experienced a somewhat similar problem a while back. Some parts were
falling off the bottom of the boards prior to wave soldering. Usually, but
not always, the parts were close to the edge of the board.

We found two problems. Some of the adhesive being used was past its
expiration date. We were doing pin transfer at that time and we found that
it would sometimes be left in the "pot" and used past its "window" of time
(hours) of usefullness after exposure to air.

Once those areas were addressed and people were educated, the problem went
away.

We never did get into measuring the pull strength, although we talked about
it.




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cc:    (bcc: Charles Barker/IO-US)
Subject:  [TN] Gen: Soldermask Adhesion




What is the typical adhesion factor (Bonding Strength) for soldermask to
the bare copper surface?
Will there be a difference in the shear factor number?
<Snip>
Has anyone else encountered similar opportunities in the past and if so
what were the conclusions?
Steve Collins
PCB Design Supervisor

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