reverse electroplating

[kilahertz]

about 50 years ago in high school chemistry class we did an electroplating experiment. It was gold plating. the teacher assisted us in mixing the required chemical solutions. exactly what they were I do not recall. we used a 24k gold anode and a gold-plated pendent cathode. we put both into a glass 1000ml beaker. using a variable power supply we started the process and almost immediately I noticed that the gold color was gone from the pendent. we shut off the power, switched the connections and restarted and the gold color came back on the pendent. we figured that because the power was reversed we had initially removed the gold from the pendent and then after correcting the polarity we successfully replated the pendent. so now my questions..
1 copper, silver, gold need different solutions to plate … what are they???
2 can platinum and rhodium be plated ??? what solutions are needed ???
3 what are the ideal voltages to use for each metal ???
4 since we were able to successfully remove the gold from the pendent I want to experiment with removing all types of PMs from a circuit board. I was thinking that I would start with copper (lowest voltage I think) then moving up to silver, then gold, then platinum, then rhodium. what equipment solutions, voltages ,etc would I need ???
5 are there other threads here that might answer some of these questions ???
6 are there books that I could purchase that have the answers ???
7 any other websites that could assist me ???

 

[FrugalRefiner]

Kilahertz, welcome to the forum. I would have to write a couple of books to fully answer your questions, as they seem simple, but they are actually very complex.

1 copper, silver, gold need different solutions to plate … what are they???

This would be the first book. There are many possible solutions for each metal.

2 can platinum and rhodium be plated ??? what solutions are needed ???

Yes they can. This would be the second book. These formulae are closely guarded secrets in the plating industry. We usually deal with removing platings. There is a forum that deals much more with plating questions. I believe it's something like finishing dot com. One of our esteemed members was also a member there, though sadly, he has passed. Maybe someone else will remember the forum.

3 what are the ideal voltages to use for each metal ???

Again, these are not simple, single answer questions. Which metal? Which solution? What concentrations? Sorry I can't give you a simple answer.

4 since we were able to successfully remove the gold from the pendent I want to experiment with removing all types of PMs from a circuit board. I was thinking that I would start with copper (lowest voltage I think) then moving up to silver, then gold, then platinum, then rhodium. what equipment solutions, voltages ,etc would I need ???

I don't think you'll enjoy success. First, for any stripping system to work, the target metal must be connected to the anode. Circuit boards aren't made that way. You would have to consider more than just voltage. Not all metals are soluble in the same solutions.

5 are there other threads here that might answer some of these questions ???

There may be bits and pieces spread throughout the forum, but we don't really deal with trying to strip metals selectively because it just doesn't work that way.

6 are there books that I could purchase that have the answers ???
7 any other websites that could assist me ???

Google the subjects you're interested in. There are a lot of old books that are no longer under copyright that you can download for free. They are old, but the principles remain the same. Newer innovations and tweaks are usually trade secrets.

Dave

 

[butcher]

1 Copper normally sulfate, silver normally nitrate, gold often cyanide are used.
Several metals can often be plated using the same electrolyte

2 Yes, rhodium is often sulfate-based. I am unsure of platinum.

3 Above the reduction potential of that metal plus some for the electrical resistive losses... often low voltages ranging from 2-6 volts.

4 good luck with that one, although it may be as much fun as watching a dog chasing his tail.

5 Yes, try the forum search function using different keywords.

6 Yes, tons of free books and information on google.

7 Yes, Google tons of information on electrolysis, books, websites videos...

8, it would take a few books to answer even part of one of these questions.

 

[g_axelsson]

2 can platinum and rhodium be plated ??? what solutions are needed ???

Yes they can. This would be the second book. These formulae are closely guarded secrets in the plating industry. We usually deal with removing platings. There is a forum that deals much more with plating questions. I believe it's something like finishing dot com. One of our esteemed members was also a member there, though sadly, he has passed. Maybe someone else will remember the forum.

Yes, I remember it. https://www.finishing.com/

Göran

 

[Lino1406]

If very much interested, for electroplating platinum you can use dinitroplatinic sulphate or platinic acid, acidic or ammoniacal solutions

 

[nickvc]

Welcome to the forum.
Perhaps you should research how circuit boards are produced on the internet and then you may start to understand the mountain you are trying to climb. It is also highly unlikely that you will encounter either platinum or rhodium on or in most circuit boards, the use of in is also a clue as to why you will not recover all the values on a board in the way you think.

 

[Goldmember123]

Hello can someone please tell me what smb gold stripping agent is ?

 

[butcher]

I do not know what the stripping agent added to the chemical name is about (possibly someone's name for selling you a common chemical at an extremely high price).

SMB is sodium metabisulfite also called sodium pyrosulfite (often found in one brand of stump remover) which is a selective reagent to reduce and to recover gold from a deNOxed aqua regia solution, as it produces SO2 gas in the acidic solution which will reduce the gold from solution, (it can also reduce the oxidation state of copper if overused)...