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Carbon treatment of copper plating bath

December 4, 2021

Q. Hi there I'm using a basic watts acid copper bath in a 40 gallon tank with continuous filtration.
H2O2 (hydrogen peroxide) is recommended for pretreatment before carbon filtering.

I'm wondering if I could use the dry form of sodium percarbonate instead. It's widely available for home brewing - and has some added chelating agents that might be useful otherwise for breaking up contaminants . Would it work?
Buying cases of small bottles of hydrogen peroxide is getting old and seems stupid. I can't get more concentrated versions over the mail.

Lmk?
Thanks!
Raphael

Raphael Lyon
- Brooklyn, New York

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⇩ Closely related postings, oldest first ⇩

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Q. I have a copper bath which is contaminated and I want to treat it with carbon treatment but I am not sure if the carbon filter will affect my copper bath.
I have never used carbon treatment for copper bath.
Is there any other way to do it ?
Thank you in advance,

Abraham Ts
Student - Minneapolis
August 2, 2008

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January 19, 2012

Q. Hi, I have a 150 Gallon Copper Pyrophosphate Electroplating Bath that I use for small quantities of private Blank Copper Masters (14" Discs). I have run into problems in the past that I was not able to fix by adjusting the chemistry of the bath (which I do in house, plus have checked periodically by an outside lab) and the only two options I am left with are:

a) Carbon Treatment;
b) Partial (or full) dump and remake of the solution

The bath I have is new (made in the last 8 weeks). I have 8,000 amp hours on both cells (I run 2 cells, that are separate, but pull from the same sump below). I've plated around 177 plates (both useable and unusable plates).

The way I have carbon treated in the bath is:

a) Remove existing filters;
b) add Activated Carbon Filters (10 micron, 30 inch) to my bath, allow it to sit for 5 - 7 hours;
c) Pull the Carbon Filters out, add new regular filters and allow it to sit for 5 - 7 hours;
d) Run several loads of parts (at least 6 to 8).

Sometimes I am back up and running after the 8th load, sometimes it takes much longer.

I cannot find something specific on this and would really like to know if the way I have it is right, or if there is another way to do it.

When I do (d) above (Run several loads of parts "Dummy Plates"), I generally run them at 40 amps (which is my operating amperage - 40 amps for 2.5 hours), and the voltage is around 1.95 - 2.0 (During the dummy plating, when not dummy plating my voltage is generally between 1.98 - 2.35).

Any assistance or direction that can be given for this, would be greatly appreciated.

Thank you very much.

Dante Ellis
Plate Shop Manager - Camarillo, California

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January 29, 2012

Q. Hi, thank you for your replies.

My part is round 14" stainless steel (about the same thickness of a vinyl record.

I plate for 40 amps at 2 hours, 30 minutes.

Our sump tank inside dimensions is 84" long x 20.5" wide x 19.5" height. I like to have 6 - 8 inches of space from the top of the fluid to the top of my tank (so we run about 11.5 - 13.5 inches of fluid in the bath or a total of 116 - 132 gallons of plating solution (we have 2 cells that pull from the same sump, each cell is 16 gallons).

We have a large sump tank at the bottom, a filter chamber that holds three (3) thirty (30) inch polyserf pleated 10 micron filters. All the solution is filtered from the sump before it goes to the cells above.

We use titanium baskets (without bags) and have been using Luvata 14 mm x 12 mm mini copper phosphorous slugs. We were using Oxygen-Free High Conductivity, but those did not give us a good result and we used the Luvata ones before when we were plating good copper.

We have air agitation for both cells and good flow.

Dante Ellis [returning]
- Camarillo, California, USA

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Q. Hi, I work with Dante but he's not here right now. You asked about the bath additions used. We use 400 ml py61h and 150 ml ammonium hydroxide per load.

We run approx. 3 loads per day and 3 loads on the night shift. Each load runs for 2 and a half hours.

I'm interested in your comments regarding a possible imbalance, could you elaborate?

Ben

Ben Richards
- Los Angeles, California
February 26, 2012

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Q. Hi Harry,

Thanks for your reply.

The information you laid out is all correct. The ammonium hydroxide percentage is 29%

The nature of the defect is tiny pitting. This is small and were it only a cosmetic issue this would not even be a concern as you have to hold the discs up in the light to even see them. However, they make noise when played as a record. They play as tiny little pops or ticks and this is non optimum and is what we are trying to resolve.

Ben

Ben Richards [returning]
- Los Angeles, California
February 29, 2012

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Q. Harry,
I have a question about a full powered carbon treatment. How long is it safe to settle out the powered carbon after the treatment before earth pack filtering it out?
There seems to be very little data on how long is too long before some organics are released back out of the carbon and into the treated bath again.
Thank you,
Jeff

Jeff Milleville
- Niagara Falls, New York. USA
January 11, 2016

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A. Hi Jeff, It has long been part of electroplating folklore that organics are released back into the plating bath if held too long in carbon. I have generally tried to follow this rule. But, I must confess I have never, knowingly, experienced the effect. Usually the question is just the opposite: how soon can I filter the bath and get on with my work. I don't know what the organic release mechanism is. I mainly worried about organics being released from carbon packs on filters. These are often run continuously and may not be changed for a week or more. Now, whether the good work done in the first few hours was undone as the week ran on I don't know. I am talking here about removal of "background" contamination. If heavy contamination was involved, packs would be changed every few hours. Can someone out there enlighten Jeff and me please? Harry Parkes - Birmingham, UK February 3, 2016 February 2, 2016 A. Good day Jeff. I, too had the same question. Here's an opinion. I found that low TOC's were readily adsorbed by the carbon (I used peroxide with the treatment), and my rule of thumb was no longer than 24 hours. I let the solution settle overnight and filter back next morning, while the solution was still warm. I think it all depends on the carbon concentration (10 g/l) and the TOC value, as this will determine the capacity of the carbon to effectively adsorb and keep active regarding the TOC value. I used a hull cell to determine the effectiveness of the treatment, lack of brightness and levelling to me, indicated a proper treatment. Any brightness told me that I waited too long, or the nature of the TOC was not properly addressed ( permanganate). Some times we would repeat the treatment. I kept a sample of the waste "sludge" and was very surprised at hull cell results a few days later. I would think it all depends on amount of carbon and TOC values. Just an opinion. Regards, Eric Bogner, Lab. Tech Aerotek Mfg. Ltd. - Whitby, Ontario, Canada

Thank you both Harry & Eric for your replies.

We keep a stock of treated copper in drums for a quick bath swap to reduce line downtime. We do the peroxide and powered carbon treatment on all our used copper solutions so anytime we need a copper bath we are starting with a fresh bath.
I recall there was a study done long ago with bath TOC's compared to the time the bath sat after treatment with the carbon left in it before filtering it out. I was just trying to update our instructions with a maximum time to let settle during treatment but I could not find any of the old studies done on this on the internet today.
Looks like we will have to pull some TOC samples to test the different times ourselves.

Thank you,
Jeff

Jeff Milleville [returning]
- Niagara Falls New York, USA
February 3, 2016