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Preventing Reddish Gold after Plating
Hi guys;
I need some assistance to solved this problem and what are the provable cause of reddish gold after electroplating. This problem is intermittent to all circuit that we plate here.
Process Manager - Cavite, Phillipines
First of two simultaneous responses -- +++++++
Cesar,
You don't mention what type of gold you are plating. Is it a hard acid gold that is cobalt or nickel hardened? A red deposit can be caused from too high a current density, too low a gold concentration in the bath, improper ph, bath contamination whether it is organic or inorganic.
1) Make sure the Au concentration and current density are both within spec.
2) Check the pH.
3) Double check temperature of the bath.
4) Make sure the brightener level is in range.
5) Have the bath checked for metallic (inorganic) impurities.
6) Put a carbon filter in the filter chamber, run for two hours, repeat process with new filter. Good Luck!
Process Engineer - Syracuse, New York
Second of two simultaneous responses -- +++++++
Hi Cesar,
Could it be a case of burnt gold plating. Please check the gold content and adjust (increase) as necessary. If you are worried about higher gold consumption due to drag out losses and prefer to operate at slightly lower gold content, you can operate at lower current density with corresponding increase in plating time to achieve the thickness required. Try increasing the solution movement as well.
regards,
- Manila, Philippines
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Hi Mark;
I used a soft gold bath or acid base gold.
regards,
- Cavite, Philippines
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Cesar,
I would still follow all suggestions instead of #4 (determination of brightener level). Germie Maravella had a good point regarding increasing the solution movement as well.
Process Engineer - Syracuse, NY USA
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Dear Sir,
Its look like copper contamination in the gold bath. However please be sure of prescribed pH and Current and Voltage densities.
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Shafiuddin A. Mohammed |
December 16, 2011
Q. Dear sir.
We are doing the Electrolytic gold plating DIRECTLY on COPPER for our microwave applications.
Whereas we are not getting the yellow colour of gold,
maybe the reason is some amount of copper is dissolving into the bath?
Pl. let me know how to remove impurities/ contamination/ metallic particles (copper), etc?
- Hyderabad, INDIA
First of two simultaneous responses -- December 27, 2011
Hi,
Reasons for reddish tint...
1. Low gild metal content in the bath
2. High pH
3. High Temperature
4. Impurities in the bath.
Hi mark ..good to see you back..if you are there most of the precious plating sections are taken care....Season's Greetings!
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T.K. Mohan plating process supplier Mumbai, India |
Second of two simultaneous responses -- December 28, 2011
Jhonson, before you start trying to remove impurities from you gold bath, do an analysis to find out what impurities you have in there. Also do a Hull Cell test to see whether it is the gold solution of the gold thickness at fault. What thickness of gold are you actually depositing?
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Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K. |