plating, anodizing, & finishing Q&As since 1989
I'm in the electroplating industry. I have a line that runs aluminum of various grades through a cleaning process, degreaser, etch, desmut, double zincate, cu cn strike then to either a silver strike silver plate, nickel strike nickel plate or an acid cu plate. All grades of aluminum plate in all these alloys without a problem. My problem is that our panels, a flat piece of aluminum, has great adhesion at the Cu CN but poor adhesion at the acid Cu, all over the part.All other products and grades of aluminum run well. We've adjusted current, amps sq/ft, time. The only difference is the racks that hold the covers are stationary while all other products rock back and forth. The bath has been carbon treated four times. We've had some success with the first load of the day after that the covers won't plate. Chemistry? Electrical? MORE DETAILS? ANY INPUT WOULD BE APPRECIATED.Robert Albrecht
Once you done carbon treatment check the brightener,chloride.
Do a hull cell panel add 3 to 5 mls brightener and 0.5 to 1.0 ml HCl,then check sulfuric Acid make 10.5 to 11.0%by volume.for Acid copper we keep copper sulphate [adv: item on eBay & Amazon]70 to 80 gm/l
Sulfuric Acid 10.5 to 11.0%,and Chloride 50 to 70 ppm.
these may help.
Occasionally we have this issue with our Cu bath but it tends to be chrome contamination from plated racks causing the adhesion issue and we use additives to fix it. In you case you say all other parts plate well except these particular aluminum plates; first I would make sure you are doing the prep for plating for that particular grade of aluminum as different types may require slightly different chemicals and/or times in desmut or etch.
Make sure your chemistry is within spec or have it sent out to your supplier for them to test also, ask them to test for contamination levels of other metals in the bath.
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