Electrical Problem

Q: I am doing plating with yellow Miralloy, but the plating finish that I get is not mirror like. Do you have any suggestions for improving the appearance of the finish? H.C.

 

A: Miralloy is a commercially available electroplating alloy that is used as a replacement for bright nickel in applications where the plated part might come in contact with an individuals skin. Why the substitution for bright nickel? Anywhere from 5 – 15% of the population is allergic to nickel and suffer from nickel dermatitis.

Miralloy is a combination of tin, copper and zinc. The nominal formulation is 55% copper, 30% tin and 15% zinc. Sometimes this formulation is called white bronze. A yellow formulation containing much larger amounts of copper is also available. The yellow formulation is used as an underplate for gold.

Besides Miralloy, other commercial products are available. Two such products are Albaloy and Optalloy.

When it comes to problems with these plating baths, the best place to start is with your chemical vendors. Typically, chemical vendors will have data sheets and technical bulletins addressing many of the common problems you may encounter with the plating.

Without knowing more about your process steps and the operating conditions of the plating bath I can’t give you any specific advice. Some general advice and areas to investigate are: Are the parts properly finished prior to plating? If the surface is rough or not pristine clean, you may have a problem. Another possible cause of a non-mirror like finish is the plating bath itself. Is it being operated within the parameters specified by the vendor? Have you checked the bath for impurities that may affect the plate finish? Is your filtration system functioning properly?