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October 2000

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Subject:
From:
"Barmuta, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 25 Oct 2000 08:32:57 -0700
Content-Type:
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Richard: It is very probable that this is a copper to soldermask adhesion
issue caused by improper processing at the fab level.
The fabricators argument will be that they went thru HAL/wash and it did not
come off. Your argument is that a SMOBC/HAL finish should stand up to
wavesolder/wash.

The mask is probably delaminating in the wave during wavesolder then being
blown off by the spray impingement at wash (just like a power washer).
A couple of things to look at and consider:

1. Is the mask only coming off on the wavesolder side of the board?
2. What is the appearance of the mask after wavesolder prior to wash, is it
starting to blister or lift?
3. In what area is the mask coming off, groundplanes, circuits, pads,
laminate etc?
4. To what degree is the mask coming off, small isolated patches in a
groundplane or large areas.
5. If you wash a none wavesoldered board does the mask come off?
6. Are the boards washed immediately i.e. continuos flow after wavesolder or
do they cool down a bit.
7. Check the cure of the mask.

The answer to these may help you win or reach a compromise with the board
fabricator.
Since the other boards are not showing this defect when run thru your same
process this helps your argument, unless the problematic board is
dramatically different in design.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-356-6076
-----Original Message-----
From: Richard E. Ackerson [mailto:[log in to unmask]]
Sent: Wednesday, October 25, 2000 7:27 AM
To: [log in to unmask]
Subject: [TN] Solder Mask Peel


I am looking for some input regarding a possible cause for a problem we are
having with one board, part number.

We recieved a lot of boards from a vendor, all with the same date code. This
is
one of meny boards we have recieved and are still recieving.
This board, however, is causing problems after wave soldering, by the
soldermask
peeling, reveling bare copper.

The boards are 4 layers, with a thickness of .093". They are SMOBC/HAL
boards.

The boards are assembled and then wave soldered using water soluble flux.
The
mask begins peeling during water wash in our Trieber SMT Cleaner.

The wave temperature is 500F. Kester Water soluble flux #2235 is used with
Kester #4662 thinner to reach SG. The flux is applied with a foam fluxer.
Preheat temperature is 220F.

The mask does not peel prior to wave soldering, only after.

My inital feelings is that there was contamination left on the copper prior
to
the soldermask operation. The vendor feels, since the mask dosen't peel
prior to
wave soldering, and didn't peel prior to their shipping, the problem is in
our
process.

This is occurring with one part number, one single lot of boards from one
vendor. We have not experienced this situation with any other of this
vendors
boards, or any othe vendor's boards.

Any Ideals?

All input will be appreciated.
Sincerely,

____________________
Richard E. Ackerson
Sr. Industrial Engineer
ABB Automation, Inc.
Electronics & Systems Assembly
Phone: 440-585-7646
Fax: 440-585-8860
[log in to unmask]

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