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Solderability problems

2002

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!

Teresita Molina
- Carson, California, USA

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

Bruce Stacy
- Greenville, South Carolina
2002

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2004

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).?

Teresita Molina
electro-mechanical relays - Hawthorne, California, USA