Paper for making printed circuit boards using the toner transfer method, or how to make a PCB at home.

First, I lay out the circuit board. I use Sprint Layout 6; before that, I used version 3 for a very long time, and I still haven’t quite gotten used to the differences in how it works.


When making a board, I always leave a 5 mm protective margin around the perimeter, so the blank is 10 mm longer and wider than the board itself. That’s what works for me.


Sand the blank with fine-grit sandpaper. What matters is not a mirror finish, but plenty of tiny scratches—the toner will stick better that way.


Print the design for our future board on the paper (I usually print two copies, just in case), on the smooth side. By the way, I did the whole process in one take: I didn't make any adjustments or redo anything specifically for this review. That was the point of the test.
Remember to print the design mirrored relative to the required PCB layout.


Next, I place the blank on a specially selected book :), or rather, it's not a book but a year's worth of Radio magazine issues bound together in cardboard. I do this so the blank won't slide around during the process, and so the heat won't damage whatever is underneath it.


Then I place the printout face down against the copper and cover it with a sheet of ordinary printer paper. This helps keep it from sliding around at first. The trickiest part is making sure the printed sheet doesn't slip sideways. I start by setting the iron down with its wide side on the book and paper, then slowly lower it onto the blank.


Next, iron the board with smooth strokes and light pressure. I make several passes from different sides to get the edges properly ironed. Don't press too hard, or the toner may smear; if you don't press at all, the toner probably won't stick to the blank. I iron a blank like this for about a minute.
By the way, I use Static Control toner. In my opinion, it's the best toner for LUT…

The transfer is complete: the paper has stuck on evenly and neatly.


Now put the board in a bowl of water for 5–10 minutes. You can leave the tap running; this will help soften the paper faster.


After 5–10 minutes, hold it under a gentle stream of water (room temperature is best) and rub the paper off with your finger. The traces should stay in place. You don't need to be overly careful: if the toner rubs off with a finger, the board needs to be redone. Properly transferred toner won't rub off; it can only be scratched off.


The photo shows the result of transferring the design onto the fiberglass board. The toner is black. Previously, when I used magazine paper, it had a grayish tint because bits of paper were left on it. Here everything looks good: the holes are clean, and there are no toner bridges between the traces.
For the test, I deliberately chose a PCB design with both large copper pours and fine traces.


Before etching, I make a little “table” like this. At the corners of the board, in areas without any traces, I drill 4 holes and insert matches (or toothpicks) into them, with the design facing down.


PCBs are usually etched in a solution of ferric chloride in water.
ru.wikipedia.org/wiki/Хлорид_железа(III)
Once the board is immersed in the solution, lift it almost immediately and remove any air bubbles; otherwise, some areas won't etch.


After a while (depending on the solution), the board is etched.


I wash off the toner, which has now served its purpose, with acetone (or any suitable solvent).


And here I'll show you the print quality I ended up with.
The processor footprint is near the center of the board. The pads are 0.45 mm wide, and the traces are 0.45–0.5 mm wide. You can see that the pad shape has been preserved perfectly.


This is a trace along the edge of the board; there are two spots like this. I usually touch these up with a permanent waterproof marker, but I deliberately left them as they were for the test.


After washing off the toner, I drill the required holes, then clean up the board with fine-grit sandpaper.


Only after all these steps do I trim off the excess. If you do this before sanding, you can damage the traces near the edge of the board with the sandpaper. I go over the board edges lightly with a needle file to remove any sharp fiberglass splinters left by the scissors.


Now I coat the board with flux (I use alcohol-based F3) and tin the traces.
I know some people skip this, but I prefer a board with tinned traces. It’s a matter of taste, of course; the copper also won’t oxidize, and the solder fills in any microcracks.


The final step is to wash off the flux residue with acetone.


That’s it, the board is ready.