PCB Etching tutorial
The first task at hand is to find the right paper. Find a glossy paper and most glossy magazine papers are sufficient. I have seen few of them use those costly photo quality papers, but haven’t found them any better. Also, do not bother about the printed content if you are using magazine sheets; it is ok to print over it as the ink does not transfer to the copper. However, avoid sheets with grease and those with bent corners. It not only spoils the print but also the printer.
Printers generally have different settings based on the paper size, type, toner efficiency etc. Set the printer such that it spits out maximum toner. I have a Samsung Laser printer and settings I choose are shown in the image (Click any image for higher resolution).
- Toner Save Mode is disabled
- “Darkness” is set to “Dark”
- Set the page type to transparency if the settings permit.
Most printers have scaling set to “Fit to page” by default. In case, set it to none as you need the printer to print the exact size without rescaling and resizing. Since my printer allows me to align the print area, I exploit it to use the same sheet for multiple prints. You can align to print on the top-most region of the sheet and then cut off the rest for future use.
As mentioned above, always use a laser printer and do not complain if your inkjet printer failed to work. Now print your circuit diagram on the glossy paper and see the results. The tracks should be dark and there should not be any sort of breaks in the image.
Hint: If you feel that the tracks are too thin, or you need to edit the circuit, go ahead and open a paint program. With experience I dare say that once you design the circuit with any design software, modifying an image with a paint program and then etching gives the best experience. You can increase the track size and other details. But do not modify the size and shape of the components. Remember to print “mirror image” of the actual circuit. Once you transfer the image onto the board you will see the real circuit.
Preparing the copper board
Copper board contains a copper layer laid over an insulating material called the substrate. Etching is creating copper tracks over the board and removing unwanted copper from the board.
Copper boards come in various sizes which should be cut to the exact size of the circuit. I used a small hacksaw to cut the board to appropriate size. Wear goggles while cutting as the fine powder produced might get into your eyes.
Once you have a decent sized board, the next task is to clean the board from oxidation, grease, oil, dust and ofcourse your finger prints. Use a fine sand paper and slightly sand the copper. If you have a kitchen scrub, then it is best suited. Do not use a metal scrubber and do not overdo the scrubbing such that you remove all the copper.
Clean the board in water (and soap, if required) and let it to dry. Do not touch the surface once you have cleaned the board.
Now you have the copper board ready. We will have to transfer the toner from the paper to the copper board.