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Leadfree plating

For the assembly industry, most people use tin/lead alloy plating on external lead of a leadframe for soldering. For the leadfree ppf, someone uses NiPd plating, but why don't people use Ag plating instead of tin/lead alloy for soldering ?

Thanks.

Kelvin Yeh
- Hong Kong

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Most of my customers like the Tin and Tin/Lead alloys because they solder so well. You only have to use a small amount of solder (or none at all) on Tin plated parts to be assembled. A small amount of Lead, usually 2-10 percent, in the Tin deposit inhibits whisker growth on electronic components. Bismuth is another option but not widely used yet. Silver is not normally used as a coating if solderability is the main reason for specifying it due to the higher cost and greater chance of oxidation which will prevent a good solder bond. I've seen customers switching to a Gold flash (5 millionths min.) over Nickel for a good Tin free coating that can be easily soldered to. The cost may be prohibitive but based on the application it may be worth it.

Jim Conner
Anoplex Software

Mabank, Texas USA