Step 3: The PCB
I won't go through the whole process here, there are plenty of guides online. But, I'll go over the basics.
Start by printing out the PCB artwork. The toner transfer method requires you to print using a laser printer on glossy photo paper - use the smoothest, shiniest stuff you can get. The bottom artwork should be printed normally, and the top artwork should be a mirror image.
Cut a piece of plain double-sided copper clad board slightly larger than the artwork, and place either the top or bottom artwork with the printed side towards the copper. Be sure the copper is clean to ensure a good transfer. You may tape the artwork to the copper clad using heat-resistant tape, to prevent it from sliding around. Now, place the board on an ironing board with the artwork on top, and lay a piece of plain paper on top. Some photo paper contains plastic that will melt onto the iron - the plain paper prevents this.
Now, with the iron on the hottest setting (and no steam!) , press down on the board for a few minutes. It's not necessary to move the iron unless the board is bigger than the iron.
After a few minutes, remove the iron and place a heavy, heat-resistant object like a cooking pot or glass baking dish on top of the board. This will keep the paper pressed against the board while the toner cools.
When the toner and board are cool, peel off the photo paper. If you're lucky and are using photo paper like I have, it will peel right off leaving the toner securely adhered to the copper. Some photo papers may require you to lightly scrub off the paper under running water.
Now, note the four mounting holes in the corners. Drill a 1/32" pilot hole in three of them. Take note of which holes these align with on the second piece of artwork, and punch a small hole in these locations on the artwork with a pin. When you line up the second piece of artwork on the copper clad board, make sure these holes line up PERFECTLY.
To prevent the toner that's already transferred from sticking to anything, lay a plain piece of paper on the ironing board, then a piece of unprinted photo paper, then the board and remaining artwork. Apply heat with the iron as before.
When both sides are transferred, inspect the board carefully for any toner that didn't transfer, and for any other damage. Repair the damage using a black fine-tip Sharpie marker.
Etch the board in either Ferric Chloride or Ammonium Persulfate according to the directions on the bottle. Inspect the board regularly to make sure that the toner and any repairs are not being etched away. When the etching is complete, thoroughly wash and dry the board with a lint-free towel. The toner and Sharpie marker are easily removed using nail polish remover and a cotton ball.
The last step is to drill the holes. I used a 1/32" bit in my drill press. This step seems to take forever, but be patient and be sure to drill in the exact centers of the holes.
- I may order a bunch of professionally-made boards from a boardhouse, at a cost of about $12 each plus shipping. If you're interested in a group buy, let me know! *