Making PCBs — Toner Transfer

The "toner transfer" method is by far the most common way that pedal builders get the circuit image onto a blank board.

Press N Peel Blue

Most folks use the ubiquitous Press N Peel Blue transfer sheets. This a a tried-and-true product that yields great results. There are many tutorials on how to use Press N Peel, so I won't beat a dead horse and repeat it here. But here's a good one from the manufacturer.

Glossy Magazine Page Method

This method is functionally quite similar in many respects to using Press N Peel. The difference is that instead of paying $2 per sheet, you can use a glossy page out of a magazine for free. If you don't have magazines laying around, local libraries often give away last month's issues of their subscriptions. Free is good. :)

Selecting the Right Paper
You want to use pages that are free of photos. Pages that are mostly text on white paper are ideal. The pages should be slightly bonded/glossy. Newspaper pages will not work. A good source for these kinds of pages are research journals and other boring academic crap. Also, the pages are going to need to be able to fit in the bypass tray of a laser printer or copy machine, so look for A4- or letter-sized magazines (no bigger than 8.5" x 11"). Either that, or trim larger pages down to letter size.

Printing the Layout Image
If you have access to a laser printer, you can print your layout image file to the magazine page via the printer's bypass tray. If you're doing this at work, be aware that magazine pages are generally thinner than standard printer paper, and it is possible that you'll cause a jam.

If you do not have access to a laser printer, print your layout image on whatever printer you have (on plain paper). Then take the printout to a copier, and copy the image onto the magazine page via the copier's bypass tray. The same jam warning as above applies.

Here's an example of some circuit layouts printed on a magazine page:

**add pic here**

Transferring the Toner
Cut out the circuit layout image from the magazine page. I suggest leaving a little extra room on all sides. Now use it as a guide to mark and cut a piece of PCB blank from a larger sheet.

Use some steel wool (or similar) to polish the copper side of the board. This removes dirt and finger grease from the copper, which helps insure a clean transfer. Make sure you give adequate attention to the edges of the board.

Now break out your clothes iron and ironing board. The proper heat setting will vary from iron to iron and will also depend on the toner. Some types of toner require higher heat than others to fully transfer. You'll just have to do some trial and error here to find the right temperature. As a starting point, I suggest setting the iron at just past it's middle setting.

With the copper side up, put the iron on the board for about 1 minute. Preheating the copper helps the paper stick firmly when applied.

Carefully align the trimmed magazine page layout paper just above the preheated copper board. Now press the paper (toner side down!) onto the copper. It should stick immediately. There are no do-overs on placement, so make sure you get it right the first time.

Now set the iron on top of the board/paper for about 45 seconds to 1 minute (the timing isn't critical). Now that the board and paper are hot, slowly run the iron over the surface of the board. Be sure to give adequate time and attention to the edges, as I find that if there is a problem with the transfer, it usually happens around the edges. Total ironing time for this step will range from 1 to 5 minutes, depending on your heat setting, toner, etc. Again, it takes some trial and error to find the right time and technique.

Carefully move the board/paper into a small bin of cold water. I keep a small plastic-ware container on the ironing board and drop the boards in as I work. Let the board soak for 5 to 10 minutes. This softens the paper for easy removal. Now peel off the paper under running water.

Most likely there will still be some backing paper after you peel off the main sheet. If there is a lot of paper left, I recommend letting it soak again for another 10 minutes. Otherwise, use your finger with light pressure to rub off the excess paper. If transferred properly, the toner will not come off the board very easily, so don't be too shy with the rubbing. If it does come off with light pressure, the transfer was insufficient, and you almost certainly would've had the toner come off during etching (which is far less desirable).

If some of the traces from the circuit design did not transfer properly, you have two choices: repair the traces with a Sharpie marker, or scrub off all of the toner and start over. If there are only a few gaps to fill in, I just use the Sharpie. Otherwise, I start over.

And now you can proceed with etching.

Troubleshooting
If you find that a significant portion of the image does not transfer to the board (eg, part of it remains on the paper when you peel it off), that means you need set your iron to a higher temperature or you did not use sufficient pressure when ironing. Try again with the same temperature but with more downward pressure. If you still get spotty results, turn up the temp.

If the toner is transferring completely but looks smudged or is pitted, your iron is too hot.