Hi Morris,

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If you look for the reactivity series of metals, you’ll find out that the silver in the silver nitrate will exchange places with the copper in the PCB.

Since that silver will not be part of the PCB, but will be a fine elemental silver powder, will fall to the bottom along with the rest of the copper etched.

If you’re not after the silver, this isn’t a concern. Actually speeds up the process.

The problem comes from the silver chloride that will form once the silver nitrate gets in contact with the chloride acid.

Silver chloride is a white solid substance that will create A BIG MESS everywhere. Sticks to everything and is a pain to clean.

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Not sure if the amount mentioned is, or not, enough to be a problem. Maybe try first with a small sample?

Swimming pool chemicals are used, among other things, in precious metals refining. But there, the silver, and other elements, are the end goal.

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Seems to me that the AgNO3 concentration is really low. I would give it a try.

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Good luck

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Nuno T.

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Hi all,

I've been using the regenerated copper chloride method for etching PCBs for years and have had very good results. One problem I do have though is getting adequate supplies of hydrogen peroxide which I use to give the solution a boost while etching a board. The local pharmacies only sell it in 100 ml bottles of 6% and even then they keep it behind the counter and give you the third degree when you ask for it. I thought I could get larger volumes from a hairdressing supply place but it turned out to mixed into a gel.

However I was at the swimming pool shop yesterday and was surprised to find 1 litre bottles of "chlorine free pool sanitizer" that contains 35% H2O2 and 0.33 g/L of silver nitrate which is 1.9 millimoles/litre. My question is, can this be used instead of pure H2O2? Should I be concerned that the AgNO3 would interfere with the etch or have a detrimental effect on the stock CuCl2 solution that I have built up over the years especially as it would accumulate?

Any advice from someone who knows more chemistry than I can remember from half a century ago would be most welcome.

Morris