• Petus
• November 12 2016
• Tutorials
• 7393 Reads
• 0 Comments

My ferric chloride was saturated and so couldn't etch. I looked for equivalent, but I found something so much better.

I found very interesting video here.
But some etching bath are very unstable or/and dangerous - e.g. hydrogen peroxide with hydrochloric acid - it excludes chlorine.

I remember on one interesting article about alternative to ferric chloride on czech webpage about electronics - mcu.cz.
Etching bath is composed from hydrogen peroxide, citric acid and salt.v

The formula is here:
Cu+ H3Cit +H2O2? H[CuCit] +2H2O

Cit = [(CH2)2C(OH)(COO)3]

What we need (the best ratio):
For 100 ml hydrogen peroxide
30g citric acid
5g salt
70ml 30% hydrogen peroxide
30ml water (couldn't be destilled)
20g citric acid
cca 3g salt

I had to buy only 3% concentration of hydrogen peroxide from pharmacy. Maybe you can buy 30% almost 1kg for the similar price and the etching will be faster and cheaper in drugstore. Keep safety rules..
If you will etch in 25 ?C it takes about 20 - 30 minutes. If you heat up it (max 45 ?C) ething takes about max 5 minutes.
If you see some bad points on my PCB, it is caused by nonoriginal toner. If I use original toner, I didn't have a problem with covering.



Etching:






Finally PCB:




homepage of tutorial [CZ]: http://mcu.cz/comment-n2985.html