Tips for Making Toner Transfer PCBs
There is plenty of information on the internet, and videos on YouTube, about making PCBs by toner transfer which I’m not going to repeat. These are simply a few tips based on my experience of doing it.
It is often suggested that you print the art-work on glossy paper torn from a magazine but I’ve never had success with it. I’ve found the best stuff is Poundland ink-jet photo paper. I’ve also tried more expensive stuff but it seemed to have a plastic coating which ended-up as a sticky mess.
If you have trouble getting a small piece of photo paper through a laser printer stick it to a sheet of A4 first. If you are using software that doesn’t allow you to say where on the page to print send a plain A4 sheet through first then stick the photo paper over the image and put it through again.
Clean the board you are going to use with steel wool, Scotch-Brite or fine sandpaper and then wipe it over with acetone or meths.
Successfully getting the toner to stick to the copper needs a lot of heat. Ideally by the time you’ve finished with the iron the back of the paper will be going brown.
When the paper has soaked it’s best to remove the bulk of it by rubbing, as opposed to peeling, it off. The last bit can be scrubbed off with an old toothbrush.
If you find some toner hasn’t stuck it’s probably best to clean the lot off and start again; acetone very quickly removes toner. If it’s only a small and non-delicate area that is effected it can be repaired. There are pens available that are specially made for drawing tracks on PCBs and some ordinary fine markers work. A lot of people specifically recommend Shapies but I’ve found they don’t work. This could be because I use sodium persulphate as an etchant rather than ferric chloride. What I use for touch-ups is either shellac or nail varnish applied with a very small brush.
For the holes I’ve found 0.7mm or 0.8mm to be a good general size, though some components will need 1mm or 1/16”.