Anan: There are quite a few things that could cause this effect. Here are a
few of the most common.
1. High Chloride: Analyze bath for chloride PPM concentration. If you do not
have that capability look at all your anodes, if they have a gray color then
that's an indicator of excessive chloride and/or polarization. All anodes
should have a uniform black film.

2. Low Additive(brightener,leveler,carrier): Check the additive levels. If
you don't have the more sophisticated analytical equipment to do this, it
can be done using a Hull Cell.

3. Torn Anode Bags: Pull the bags inspect for tears or holes. This can be
done visually or you can fill them with water and check for leaks.

4. Sulfuric Acid(high) and Copper Sulfate(low) out of balance: Analyze for
concentration and ratio.

5. Metallic Contamination: Analyze for trace metal impurities. Such things
as lead can cause roughness. Dummy plate bath at low current density with
corrugated dummy panels.

6.Incorrect Anodes: Make sure you are using phosphorized copper
(0.03-0.08%)anodes.

7. Old or Contaminated Sulfuric Predip:Make up a new predip.

8. Bad Rectifier: The rectifier could be working incorrectly putting out
excessive ripple or amperage variation at times. Check rectifier for correct
output.


Question: Does it appear in high or low current density areas? Does it
appear to be in one area of the plating tank?


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Anan Zreik
Sent: Thursday, September 01, 2005 6:19 AM
To: [log in to unmask]
Subject: [TN] chocolate plating


'
Hi every body :

every so often for a long period of time we get a "chocolate copper"
residue on the surface of our boards on our electrolytic copper plating
line . This "chocolate plating" can be removed by hand , and it is not
connected to the copper below .

does anybody know this phenomena , and its cause??

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