Thursday, March 19, 2009

Electroplating on Magnesium and Magnesium Alloys

Metals are plated on magnesium for solderability; r.f grounding, hermatic sealing, wear resistance, corrosion protection, appearance, electrical conductivity, and for control of radiation by absorption and emission. Magnesium is electronegative and highly reactive to wet aerated and chloride-containing environments which cause the rapid formation of an alkaline surface film. As a result of this property, magnesium cannot be plated with conventional preplate procedure.

Two preplate methods for magnesium have been proved in production. These are the zinc immersion (zincates) process and direct plating without a zinc immersion coating by utilizing fluoride in the plating solution. The mechanism of the latter method is based on the inhibiting action of fluoride on the magnesium. This technique works particularly well for the application of electroless nickel directly on magnesium.

The most widely used preplate process for magnesium wrought and cast alloy is zincates. The essential steps in the process are cleaning, pickling, activation and initial copper strike plating solution. The detail of electroplating using zincates will discussed more detail further.

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