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Acid copper peeling/Dummying of chrome?
Q. Hi,
I have a new decorative chrome plating shop. We are producing some nice parts but are naturally having some problems to work through.
1.My first problem is with intermittent peeling of the bright acid copper from the bright nickel strike coat. The bath temp is 80 F and current density is .25 amp/sq. in. as per suppliers recommendation. The part is dip rinsed then spray rinsed and moved directly to the copper(less then 30 sec's). Current is applied to the part as it is lowered into the bath. We can plate two identical parts,one after the other, with one just fine and the other with spots of blistering or peeling.The nickel stays just fine.
2. My second problem is the initial dummying of chrome at the start of the day(anodes are left in the bath over night.)
We place the 250 sq. in. corrugated dummy in the bath, crank the rectifier up to full 7 volts and most amp we can get is 10-15 after 30 minutes. We can remove the anodes and sand the crust off and all is OK for rest of the day. The next day have to sand again. Is this normal?
Thanks very much for any help,
Jay Murphy- Grafton, West Virginia, USA
2003
A. It would be much simpler to take the anodes out and store them in a tank (drum) full of water-to above the top of the lead. This should maintain the brown-black lead oxide coating and avoid the yellow lead chromate film. After you put them back in the tank,a few minutes at max voltage with a small cathode -- say 10% of the anode and you should be in fine shape. Quicker, easier less expensive and no haz waste to get rid of.
James Watts- Navarre, Florida
2003
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A. If you want to solve acid copper peeling from nickel you may be try this:
1.after plate nickel bath rinse with water and dip in Uni650 (come from Atotech ) about 2 minutes and plate in acid copper but you must supply current before you dip your work in copper tank.
2. If first method not work ,I have one other method that is after nickel plating you should have pyrophosphate copper plating about 5 min and go to the acid copper . This is the best solving of this problem. It 's sure.
- Bangkok, Thailand
2003
Thanks very much for the responses, I will try the suggestions and post how they worked in the future.
Best regards,
Jay Murphy [returning]- Grafton, West Virginia, USA
2003
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