Having read much of what is readily available on the web concerning DIY PCB Etching, when the need arose, I decided to etch a board two ways – first with the Vinegar & Salt method and second with the sponge and Ferric Chloride method. Some folks are using Muriatic Acid but I didn’t try that.
The Vinegar & Salt method does work albeit slowly. Etching my small board took two hours. The formula that I used was equal parts of Vinegar and Hydrogen Peroxide and a few tablespoons of table salt. Keep adding salt until the “fizzing” continues all by itself. The liquid starts out clear but then turns an attractive shade of blue – see photo below.
The sponge and Ferric Chloride method works extremely well, etching the same board in a couple of minutes. In the past, I used Ferric Chloride to etch boards by placing them into a bath of Ferric Chloride. Even with agitation, etching a board could take ten minutes, or so. The sponge and Ferric Chloride method accelerates the etching by continuously rubbing the surface with a sponge soaked in Ferric Chloride. The rubbing removes the oxide layer that continuously builds up, permitting the Ferric Chloride to get to the raw metal and thus accelerate etching. Instead of a tub of etchant, a couple of tablespoons is all that is needed, which will make a bottle of Ferric Chloride last for a very, very long time. The technique is simple. Don plastic gloves; pour a couple of tablespoons of Ferric Chloride into a small container; soak a small piece of soft sponge in the Ferric Chloride; continuously, lightly rub the saturated sponge on the PCB. In a couple of minutes the board will be done. Little mess and little Ferric Chloride to dispose of.