More Blisters

We are plating Type 303 stainless steel with copper using a cyanide copper plating bath. After the completion of the cyanide plating step, we observe blisters on the surface of the parts. We use 5-gal tanks. What are we doing wrong?


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Q. We are plating Type 303 stainless steel with copper using a cyanide copper plating bath. After the completion of the cyanide plating step, we observe blisters on the surface of the parts. We use 5-gal tanks. What are we doing wrong? I.C.

 

A.Your e-mail does not mention the process you are currently using to plate the Type 303 stainless., nor do you mention how the surface is prepared prior to plating.

It is a given that it is very difficult, if not impossible, to plate copper directly onto a stainless steel surface. Normally a Woods nickel strike is applied before the copper plating. There are many formulations for a Woods nickel strike. One such formulation is as follows:

 

Component Concentration
Nickel (as nickel chloride) 6 oz/gal
Hydrochloric acid 10% by volume
Anodes Nickel
Control Factors Range
Temperature, °F 75–85
Current density, ASF 45–50
Time, sec 30–60

 

After applying the Woods Nickel, rinse quickly and thoroughly and immediately place in the cyanide copper plating bath.
Something else to consider: Using small plating tanks makes it very difficult to get consistent results. I recommend larger tanks, 25–50 gal, for the process. Larger tanks allow you to maintain temperature and chemical component concentrations more accurately.

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