Solderability problems

For about nine months, we were having solderability problems on palladium/nickel and gold plated header seal assemblies.

These parts went through the following process:

a. 60Sn/40Pb solder dipped (pins/leads only)
b. pins/leads were trimmed
c. pins/leads were formed (90 degrees)

After the last operation, the parts were inspected and it was flaking inside the bent area. We did a cross-section and it appeared that the palladium/nickel plating is still intact.

My question is, what caused the solder to separate from the palladium/nickel plating?

Is there a possibility that the palladium/nickel alloy could create the problem?

What could happen if the alloy have changed from 70Pd/30Ni to 80%Pd/20%Ni?

What about if the chelating agent for the nickel concentrate have changed in concentration?

Thank you so much for your help!

Alloy composition of the PdNi is probably not an issue. What type of flux are you using before solder dipping? Perhaps there is a codeposited organics in the Pd Ni deposit or rognics or oxides on the PdNi surface? Try a more active flux

Thank you for the response. Question: If within a pin or lead, the palladium/nickel thickness (underplate) and gold thickness (overplate) differs in thickness from one end to the other end, will it affect the intermetallic growth and thickness of the solder (Sn60/Pb40).?