Metal finishing Q&As since 1989

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Hand solderability of gold finish

I am hoping you can provide some insight which will help me in a project I am working on. We are looking into a PCB design which would have a board edge connector on one end, and a cable hand-soldered on the other. It would be a small board, maybe 20 x 40 mm. For the board edge connector pads we would want a gold finish which was durable, i.e. could survive tens of mating cycles (way less than 100 but more than 10). In talking with my manager about this, he called this finish a "hard gold" finish, which he then clarified as electroplated gold. Because the board is so small, I was thinking we could just have the same gold finish on the entire board, including the holes where the cable would be hand-soldered. I assumed this gold finish would be good for the hand-solder operation. But my manager said he had heard or read that there might be some concerns with hand-soldering to a hard gold finish. He didn't say whether it was because the soldering itself was difficult or unreliable, or if the long-term reliability was suspect. Can you enlighten me on this subject?

Frank Clifton
Electrical Design - Minneapolis, MN, USA
2007

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Your manager sounds quite knowledgable about metal finishing, Frank. Yes, it is generally considered a bad idea to gold plate these soldered areas because the gold can alloy with the solder, forming intermetallics that are less reliable.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007