Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I just started doing toner transfer this week after having used a different process for a few years that required too many setup steps. While waiting for my Pulsar Toner Transfer Paper to show up from Mouser, I tried some paper from Staples that was suggested on this list a number of months ago.

My laser printer is also one of the highly-regarded printers for this, the LaserJet Pro hp1525. I'm doing double-sided 1/16" 1/2oz double-sided 4x6" boards. My traces are all around 16mil. I scrub the board with green Scotch-Brite or 0000 steel wool, and then wipe off with an old T-shirt and IPA.

I initially used a friend's off-the-shelf Scotch or 3M laminator for a few tries and found that it didn't get hot enough to stick the toner onto the board without peeling off some of the toner during the paper soak/removal.

I then tried a regular $20 Black and Decker hand iron with no water in it on its highest setting for 3 minutes. I found that the heat adhered both the toner as well as the glossy coating on the paper to the board. It also caused the toner to pancake-out -- almost certainly due to too much heat. It additionally made paper removal all but impossible.

One by one I decreased the heat setting on the iron from 7 down to 3 on successive boards, and decreased ironing time to 1 minute per side with pretty good pressure and that appeared to work perfectly. I let the paper soak for an hour before trying to remove it, but I'm guessing that 2-3 minutes would have been enough. The paper slid pretty much entirely off without having to touch it. The detail and sharpness was comparable to the original paper print after the transfer was complete.

When I laid out the paper print I did so such that the front and back designs faced each other along one axis and added fiducials on opposite corners to facilitate alignment. This enabled me to line-up the top and bottom layers by folding the paper over on itself while holding it up to a light and creasing it along its common edge. I slipped the board in between the two layers and initially taped-down one opposite edge. I then flipped it over and after tensioning, taped-down the other side's crease-opposing edge.

I just got done etching it an hour ago and it etched perfectly. Front to back registration was perfect.

It has worked out well enough that I don't think that I'll even need my Pulsar TTF and TRF, but I may break into it if I need to once I attempt 8-10mil. For the time being, I don't feel like I need to fork out the $90 for the GBC(?) laminator.

I also happen to use 0.8mm drill holes for DIP/header pins as well as vias (the latter which could be smaller if I chose to swap bits). If you use a low-speed drill, you're much more likely to rip off the copper around the hole, so you really want something high-speed like a Dremel, all other things being equal.

-ebw