We are silver plating aluminum substrates using a proprietary zincate and Wood’s nickel strike prior to silver plating. We find that when we try to solder the parts, the parts blister. Do you have any suggestions on how to eliminate this problem? K. M.
From your brief description of the problem, it sounds like you are using the Wood’s nickel strike directly over the zincate layer. It is very possible that the Wood’s nickel strike is to acidic and is damaging the zincate layer. There are two possible solutions that you might try. One is to substitute a Watts nickel bath for the Wood’s nickel bath, the other is to try a copper plate on the zincate layer prior to the nickel plating step.