Pitting in Acid Copper bath.

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A. Without more information, my first guess would be a contaminant. First question: How do the hull cells compare between the three baths (or CVS, or HPLC, or however you control the organics)? Second question: Are you running three copper baths on one pretreatment line, or are the pretreatment lines separate? Third question: How well do the three baths compare electrically? Are there significant differences in the electrical parameters required to get the same plate? Finally, have you tried a designed experiment to nail down the differences (variation)?

I'm sure that there are other branches to this decision tree, but that is where I would start..Good Luck!

A. Tom

My first thought was too much chloride, but making up a new bath and having the same problem leads me to think that It would be somewhere else, .....

Are the rectifiers different, If you're actually taking about the deposit is not leveling the same is the thickness of the deposit thinner, different racks and their connections, connections to the anodes, anode surface/ tank, Stray current

Basically I would start back tracking on what is different between the 3 lines.

A. My first thought is filtration. Where are the pits, all over the parts or on the shelf? Try to filter 1 liter on a Watman paper and than look at the residue on the paper.

A. Hi Tom , I trust that you are using some sort of proprietary chemistry , from one of the many supply houses out there ? If not I would suggest that you do so , All things being equal , as you say they are then the answer lies in the tank its construction , what is it made from ? is it a new plastic tank that was not leached before use ? Is there something different about the Rectifier supplying the tank ? If all the chemistries are equal then the answer lies outside the chemistry . regards

A. Hi Tom G !

I wanted to ask a question when your inquiry first came out but felt that my limited 'background' in plating would be, as it sure seems, to be better answered by all the expert opinions you already have.

The last advice from the Land of Oz asked the question I really wanted to ask.... WHAT material is that 3rd tank made from? And then John C.T's query about a new (?) plastic tank that was not leached out beforehand (which I cannot really fathom) infers the lead question of was that 3rd tank previously used for something else and hence one now gets contamination?

All new(ish) plastic tanks (PVC, Pe, PP, PVDF, CPVC etc.) are made from essentially totally inert materials and really should not contribute to problems of your nature. Or am I up a gum tree and you are using fiberglass tanks in which case a scratched FRP tank might harbor contaminants as the material is heterogeneous.

In all fairness to all the people trying to help you, if you succeed in solving your problem, PLEASE let us know so we can stop biting our fingernails.

Cheers !

A. Tom,

The things that I would check on a rectifier, is first ripple at your plating amps the more ripple the poorer DC current, I would also check my cables /connections at a given time are the cables connections hotter / warmer than on other baths, you said that the solution in the 3rd tank didn't cover a "Flaw as well as as other baths" Could be like a LCD problem, do the rest of the parts have the same as plated brightness depth of the deposit.

Chris