Lou:

Some years back, Hewlett Packard, Loveland Colorado, put in a new spec for
soldermask adhesion that required the mask to stick to through tests that
virtually destroyed the mask.

They looked at every conceivable surface treatment, and found that, properly
done, they all gave pretty much the same results, and were very inadequate to
the test, save one treatment.  That treatment was "Black Oxide".

However they found that the oxide could be so light in color that it was
invisible.  They did install a line, yes, he said immodestly, it used our
chemistry, that sprayed the oxide on to the panels, for a very short
duration, and at a low temperature, and the panels did not look any different
after the "oxide" than before.  Yet, the soldermask adhesion improved so
dramatically that there was no comparison.  And the mask would literally
stick until it was destroyed.  And this was the only surface treatment that
even came close to this type of performance.  They were using both dry film
soldermask, and liquid photoimageable.


This company is now Merix Colorado, and I do not know if they are still
running the process.  Hewlett Packard was buying a chemistry/equipment
package, and unfortunately for us, the equipment vendor that we worked with
did not support this application, and they threw the equipment out, and our
chemistry with it, and switched to Shipley/Schmid chemistry and equipment.
  I suspect that this is likely still a standard finish for all boards
produced at this facility.  They were extremely pleased with the performance,
and appearance, or the panels.

Hope this helps.

If you need further information, do not hesitate to call, or write.

Rudy Sedlak
RD Chemical Company
[log in to unmask]
Phone 415-962-8004

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