Toner Transfer PCB etching description:

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Using gloss paper and print the PCB PDF image out on a laser printer. For my laser printer, I prefer "70# Gloss Book" from my local offset printer, it works just as well as any of the overpriced paper that I have tried for PCB toner transfer. Some laser printers work better with 80# and some need a laser paper sheet on the back to be able to grip properly. 60# may work too and softens well in water, but almost always needs to be taped to a laser paper sheet so it doesn't jam the printer or bubble up. Color copiers may work for output, although the toner/dry ink used tends to spread out more when transferring.
Take the single sided PCB and lightly sand the PCB down to remove any contaminants and to provide an adequate surface for the toner to adhere to. Sand in a circular pattern. It should look shiny and clean when you are done. Firmly wipe off any copper dust so the surface is totally clean.
Place the laser paper over PCB copper, face down and firmly press a hot clothes iron down on the back side of the paper. A laminating machine may work for this as well, if you have access to one. You should see a change in the color of the paper where the toner is as the toner adheres properly.
Put the PCB and attached paper in water and wait for the water to soften the paper. The paper should slide away from the board easily once the paper and toner are separate. Dry the board off and inspect it for any broken lines.
Most etching solutions will be able to penetrate any paper or paper gloss coating and have a hard time penetrating the toner. Don't worry too much about cleaning the paper remnants/coating (which turns white) or lines here unless the toner has spread to touch each other. This happens if too great a force was used when attaching the toner to the PCB.
If there are trace breaks or too large a section that are touching incorrectly, either repair it with pcb touchup pens, scrape the toner off with some sort of razor blade (be careful!) or sand the toner off and try again. Some toner will come off with solvents, if you can, it is better to clean it off without sanding as it thins the copper down to sand it, but otherwise, carefully sand it off and retry.
Trim the board down to the intended size, or just slightly larger. No reason to put excess copper in the etching solution when it's not necessary.
Place the prepared board in the tray of etching solution and etch per directions of etchant. Agitated warm solution should etch smoothly, but remember to let the open areas clear out completely. It is OK to leave it in a little bit longer than normal, since the toner usually spreads slightly a little bit of undercutting doesn't usually hurt and it stops random shorts that could happen otherwise on any tight traces.
Once it's done etching, pour the etchant into a storage bottle, rinse the board off with clean water and dry. Remember that most etchant can last a long time and many rounds of etching, so it's better to save it if possible and reuse it until it takes excessive time to etch.
Drill out any holes with appropriate size drill bits. The most common size bit I use is #60, but some of the holes are larger.
Once all the holes are drilled, sand the toner off the remaining traces till they are shiny and inspect for bridged lines and clean them up with a razor blade. (be careful!)
Test the board with a continuity tester to verify that there are no shorts by testing any traces that fall close to each other - this is much easer to do while the board is clear of parts.
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