How to etch a PCB using blue press and peel film from Jaycar Electronics.
Hi Everyone,
Thought I would start a thread on this topic, since I have had some experience with it, anyway, most people getting into building DIY pedals will, at some stage, want to have a go at making, or etching, a proper PCB, or Printed Circuit Board for their DIY pedal builds.
So, for starters, what is a Printed Circuit Board and why do we need them?, a Printed Circuit Board consists of an insulating material which has had a thin sheet of copper foil glued to one or both sides of it, the insulating material can be made from phenolic (a mixture of phenolic-resin and paper pressed together under high pressure), fibreglass, or even ceramic, in the early days of printed circuit boards Bakelite was even used too, the thin sheet of copper foil glued to one or both sides of the insulating material, in the case of double-sided PCBs, is just copper that has been flattened out so it's very thin, about the same thickness as aluminium kitchen foil, copper is used for two reasons, firstly it exhibits relatively low resistance to electricity, secondly it can be easily soldered to.
The copper foil is used to form the electrical wires that join electronic parts together to form an electronic circuit, this is done by using a special chemical, called an etchant, to dissolve, or etch-away the unwanted parts of the copper, the wanted parts of the copper are protected from the etchant by coating them with another special chemical, called a resist because it resists the the chemical etching of the etchant, there are two main chemicals used as an etchant, one is called ferric chloride, the other is called ammonium persulphate, personally, I prefer to use ammonium persulphate since it is less messy and easier to deal with than ferric chloride, both etchants produce about the same results.
Once all the unwanted copper has been etched away by the chemical etchant, small holes for the electronic parts leads are drilled through both the copper foil and the insulating material, and then the parts leads are soldered to the copper foil and trimmed.
The reason for using PCBs to make a DIY pedal is that it neatens things up, it also reduces the possibility of wiring errors and saves time.
Years ago, if you wanted to etch a Printed Circuit Board, you had to buy a lot of expensive equipment and chemicals, and have access to a photographic dark room, in the 90's, some clever people worked out that you could produce Printed Circuit Boards of usable quality, at home, with a computer, a laser printer, some specially designed plastic film, the PCB artwork, chemical etchants and a small etchant tank, and a standard domestic electric clothes iron, you no longer needed to have access to a photographic dark room, all you needed to do was to print the artwork onto the film and then transfer it onto the copper foil before etching, this relies on the fact that the black toner powder used in laser printers softens when heated and it adheres to the surface it is printed on, furthermore, it was discovered that the black toner powder worked very well as an etchant resist as well.
As it just so happens, Jaycar Electronics stock both the chemical etchants and something called blue press and peel film, I just checked my Jaycar Electronics catalogue and they do indeed stock blue press and peel film, the catalog number is HG-9980, I used some to etch a PCB for my Univibe pedal and I got pretty good results.
As Andy40 has demonstrated in another thread, you don't necessarily have to print the PCB artwork onto press and peel film, you can also print it onto a sheet of paper from a magazine, and still get very useable results.
