Copper corrosion and copper sulfate crystals on silver plated copper parts

Q. Hello.

I am investigated some problem that we have in my company. From our supplier we received some silver plated copper parts with different defects such as corrosion of copper, and copper sulfate crystals on the surface. The corrosion is not noticed right after metallization but only two or three days after it.
When heating the parts (our process) we have problems with "bladders" on the surface, scaling of silver metallization and with the oxidation of copper.
Before treatment we wash and prepare the parts in perchloroethlene.
Supplier also makes other metalizations such as nickel and copper plating, and tinning.

I would appreciate any suggestion or advice about where and why these defects occur.

Thank you.