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48:26 1997 |
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| >From willli Mon Jul 7 12: |
08:39 1997 |
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Most aqueous LPI solder masks on the market are mixtures of epoxy resin
systems with acrylate resins/monomers. The acrylates react quickly to free
radical type polymerization (initiated by UV radiation) through the double
bonds (as you stated).
The epoxy resin does give desirable properties, such as electrical
insulation, chemical resistance, toughness, etc.
There are some all epoxy LPI masks on the market. The most common are the
Probimer 52 type solvent developed products from Ciba-Geigy. They use
different type photoinitiation systems and are very slow reacting (often
taking minutes) in typical UV type exposure units.
I am not aware of all acrylate LPI mask, but I suppose these would be
possible. Overall properties would probably not be quite as good as the ones
with epoxy resins in the system.
Hope this helps.
Larry Fisher
Dexter Electronic Materials
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