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February 1997

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Sun, 9 Feb 1997 22:37:37 -0500 (EST)
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Although many companies have worked on or are working on water borne solder
masks, the results to date have not been that positive. Some of the problems
are:

1. Critters like to live and breed in water borne organic materials (fungus,
mostly) and putting in anti fungal ingredients into the formulas do not
usually enhance the performance of the solder masks.

2. Its hard enough to get a good performing solder mask in a solvent borne
system. Much harder in a water borne system. Any water borne mask would have
to be soluble in water and, therefore, would be more susceptible to any
aqueous system even after final cure. The average PWB is subjected to all
kinds of high temperature aqueous systems, both alkaline and acid and solder
mask breakdown can be a major concern.

3. Water borne systems tend to be based on emulsions and are notorious for
difficulty in controlling these emulsions, batch to batch inconsistencies,
stability problems, freezing during shipping (like into upstate New York in
February), etc.

Don't mean to throw "cold water" on water borne masks, but I don't think they
are there yet. If someone has a good one, more power to them and I'd love
tolearn more about it.

Larry Fisher
Dexter Electronic Materials
[log in to unmask]

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