Blisters on Silver Plating

I have an assembled part that has both beryllium copper & brass, this assembly is silver plated and then we solder with 1.5% silver solder another part to it. We are encountering tiny bubbles or blisters on the beryllium copper part of the assembly. When the part is being silver soldered it is being brought up to temperature by placing the assembly on a hot plate. What would cause this condition and how can it be corrected ?

Thank you

It sounds like your beryllium copper still had an oxide coating on it prior to plating. Persulphate based activators work well. A good strike should be applied to help the adhesion...either cyanide copper or Woods nickel. The parts should withstand soldering temperatures without blistering.