Homemade PCBs with a Brother Printer - 4mil Traces

So I’ve done a bunch of tests with different paper, and the best paper I found for the job was this yellow stuff off of ebay here. I think this is the key part to getting such good results.

It took a couple of tries to get the toner to stick to it, but in the end I got it working by taping a piece of it to some plan paper with kapton tape.

Taping the Yellow Paper to Regular Paper

I use a pretty standard way of transferring the toner to the PCB. I just tape down the toner transfer paper to the PCB, put a paper towel over it, and iron it on (two minutes seems to work good). After the two minutes, I spray the towel and PCB with water and iron it out – I repeat that for about one minute.

After that I let the PCB cool, and wash off the toner paper in cool water.

For etching I use strait ferric chloride in a squarish plastic container. It usually takes about 20 minutes to etch if I agitate the container, or less if I rub the ferric chloride on the board:

Etching the PCB
Etching the PCB

I then rinse off the board in cold water again, and remove the toner with lacquer thinner or acetone. And that’s all!

Final PCB
Finished Test Board

(The first trace on the top-left is 2 mil, and the next one is 4 mil)

With this method I have reliably got down to 4 mil traces - I did get a 2 mil trace, but it was starting to have higher resistance (I wouldn’t trust it at all)…

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