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Procedures for plating nickel over tin

WE HAVE A PROJECT TO ELECTROPLATE 30 MICRO IN. OF TIN sulphate OR TIN MSA OVER A COPPER BASE METAL FOLLOWED BY 30 MICRO IN. OF NICKEL SULFAMATE.

TEST REQUIRED: 170 °C FOR 4 HOURS. BEND TEST ON 40 MM MANDREL

IS THERE ANY INFORMATION AVAILABLE FOR THE PLATING OF NICKEL OVER TIN PLATE AS TO ITS CORROSION AND DUCTILITY ?

LOUIS HIRBOUR
- Providence, Rhode Island
1996

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Interesting. Ni/Sn/Cu is exactly opposite of what is common in electronics: Sn/Ni/Cu. But the 170'C @ 4 hours should be a breeze to pass over a 40 mm mandrel. Any observed ductility problems with the Ni would stem entirely from the conditions under which the Ni was deposited. Your supplier should be able to offer you a set of graphs indicating which parameters (Temp, pH, ASF, etc...) yield the lowest stress condition. Use this set as the starting point. Beware that the resultant ductility will be a strong function also of the solution flow condition at the surface of your workpiece, hence the vendors graphs can only be used a a good first guess. But with only 30 microinches of Ni, it should fly through the bend test. I used to make this test on leadframes with 70+ microinches of Ni without even orange peel. Good Luck,

Dave Kinghorn
Chemical Engineer
SUNNYvale, California
1996

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I suppose I would put a copper strike between the tin and the nickel, never having done this.

  
Tom Pullizzi
Falls Township, Pennsylvania
1996