(Mostly) easy PCB manufacture

Step 7 Etch

Drop the board into your etch solution. Don't let the etch chemical get onto anything made of metal! I use a large plastic containter. Etch the board until the remaining copper is gone. Depending on how fresh & warm the etch chemical is, it could take 10-30 minutes.

Comments

[buiocchi]

what is the importance of dipping it into the etching liquid?

[CyberBill]

Etchant essentially eats the copper off of the PCB. The point of doing the toner transfer is so that certain areas of the copper-clad PCB are covered up by toner (a permanent marker does the same thing), and thus protects the copper from being eaten by the etchant. Afterwards, you just use the fingernail polish remover (acetone) to clean the toner/marker off of the board, which reveals the still in-tact copper below it.

[nickjohnson]

Is there any good way to agitate or heat the etching solution? I was thinking of using a glass container with a halogen lamp against it, or to put the whole thing on a turntable.

[Dodgy]

Constant agitation is virtually essential. You can use a brush or a stick to move the board around or to move the etchant over the surface(s) of the board so as to always have some fresh etchant on the copper, and therefore homogenise the dissolved copper.

If the etchant is hotter, it will work better (ferric chloride). But don't make it over about 80deg C, or the fumes could start eating into the copper wiring in your ceiling light (probably not). Or your health may suffer from breathing it in.

Ammonium persulphate apparently needs to be in a window zone of temperature.

As for the hydrochloric acid and hydrogen peroxide method.... Apparently it can become an exothermic reaction and provide heat to itself, eventually exploding... So I wouldn't overheat that, if possible!