The effect of plating solutions on soldermask is dependent on several factors:

Because thes majority of soldermasks are aqueous developable, they are prone
to attack by high pH solutions. this can destroy the integrity of the mask and
allow degradation of the circuitry below it.

Since most of the masks have a low Tg they are prone to lifting and bubbling
during the high temperature cycle in the electroless Ni bath. This can result
in pinholes which allows Nickel to deposit randomly and could in the worst
scenario lead to shorts. In addition adhesion is destroyed and the mask will
no longer meet IPC specs.

Sometimes the inegrity of the mask is kept, but the copper underneath is
oxidized. This may be just cosmetic but could also be funtional because of
degradation of the mask above it.

Leo Roos

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