HOME FAQs BOOKS JOBS: Help Wanted Suggestions      you are here: Hotline/Forum => Letter 1102

---

Pitting problem with acid copper plating

--

I am having a pitting problem in an acid copper plating bath. The parts are 3 dimensional bronze plumbing parts. The parts are sanded, vapor degreased, electrocleaned, acid cleaned, 10% sulfuric, then plated at 10 to 15 ASF. The bath is 25 opg CuSO4, 4%v.v. sulfuric and 95 ppm Cl-. The bath is air agitated. The bath has been carbon treated 2 months ago when this problem came up, but it didn't help. The bath was analyzed for metals as follows:

Nickel 210 ppm

Zinc 55 ppm

Iron 350ppm

Lead 11 ppm

Cadmium 60ppm

The bath is bright blue.

If anyone has any suggestions I would appreciate them.

chris Shea

---

---

Check for a source of fine bubbles. Is there an air leak in the suction side of your filter pump?

Bill Vins microwave & cable assemblies Mesa (what a place-a), Arizona

---

--

Try to plate an non casted part and look if the problem still exist.

If there is no pits you have to change your pretreatments.

If the problem is your plating bath add an anti-pitting agent to your bath.

Gabriel Schonwald Interplate Ltd. Bnei Berak, Israel

---

---

I have seen this a lot of times, pitting on bright acid copper can be controlled by very very good filtering.

Sara Michaeli     chemical process supplier Israel

---

---

Dear Chris, Try a cyanide copper strike first,the concentrated sulfuric acid from the bath will have a tendency to pit before plating. Also a little wetting agent will help.

Good luck,
David

David Guleserian
- Rhode Island

---

---

I think I'd side with David on this one. Depending on the alloy, I would not be surprised to see that the acid copper bath is attacking it. Looking with low power magnification (loupe), is this 'pitting' perfect hemispherical craters that would be associated with gas evolution from some source, or is it roughness?

Ted Mooney, P.E. finishing.com Brick, New Jersey

---

-

Dear Chris,

Try to add to your pickling bath before Cu plating some amount of brightener you use with copper plating bath. Let me know if this help you overcome your pitting problems.

Best regards
Jerzy Skowronek

Skowronek Jerzy
- Water Treatment Cooperation - Sweden

---

-

SOUNDS TO ME THE CHLORIDES ARE TO HIGH. I WOULD DECANT TO REDUCE TO AROUND 60 PPM. HIGH CHLORIDES WILL AFFECT THE CARRIER COMPONENT IN THE HIGH CURRENT DENSITIES CAUSING STRIATIONS AND MAKES IT HARDER TO CONTROL BRIGHTENERS. IF ANTI-PIT AGENT DOESNT WORK, I'D TRY THIS NEXT,IF ALL CLEANING POSSIBILITIES HAVE BEEN PERFORMED ON THE PARTS.

JOHN ROLLINS
PLATING - FRIDLEY Minnesota