After spending a small fortune (well, not really) for commercially manufactured printed circuit boards, I decided to start making my own (for the low volume, low complexity). There are plenty of tutorials for this on the web, so this article will only chronicle my attempts (e.g., successes) and experimentation (e.g., failures).
The overall process is pretty straightforward. Mask off copper on a blank board, etch the unmasked copper off, clean the board. So far, the first step has proven to be pretty difficult.
Now, a few years ago I tried this and was pretty successful. However, that was like 1985 and my smallest trace was probably a 1000 mils or so. This time around I tried an surface mount device board, no through-holes, and 8 mil traces. That’s pretty darn small for any manufacturing process, let alone a do-it-yourself process using a print, and iron, and some glossy paper.
The exact process I’m using is well documented here.
Here’s a picture of the materials used.
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- Muriatic Acid
- Lacquer Thinner
- Hydrogen Peroxide
- Household Iron
- Latex or Neoprene Gloves
- Scotch-Brite Pad
- Copper-cladded circuit board
- Glass Measuring Vessel
- Plastic etching vessel (not shown)
The first step in the process is to cut the copper clad to your required dimensions. Try to not touch the copper surface where the PCB will be etched (it helps keep the board clean). Once the board is trimmed to size, time to clean the board. You clean the board by rubbing the board with the scotch-brite pad, in one direction until the copper is nice and shiny. Now, put the gloves on and wipe the board down with lacquer thinner. The thinner cleans oil and other contaminates off the board.
The board should look like the below, when compared to the uncleaned board (also below).
After the board is cleaned, place the PCB outline on the board.
Now, very carefully place the hot iron on the board. DO NOT MOVE THE PAPER OR THE IRON. You will be amazed how hard this step is in reality. I think there is where my first attempt went awry.
After 1 minute of constant pressure, move the iron around and ensure the entire board is heated evenly. Do this for another minute or two.
Take the heated PCB and put it in cold water for at least 5 minutes. Once the paper is fully saturated, peal the paper off. Put the PCB back into the cold water if the paper does not come off fully.
Rub the board with your finger to get all the paper off.
My first attempt at transferring the pattern to the copper was not terribly successful as shown below.
This board is application is simply not usable for etching, so I’ll have to try again. Either I moved the iron too much, or the traces and pads were simply too small. I’ll try another time trying to hold the iron still, and then again with bigger traces and pads.
(to be continued soon).