Authors: Taylor Jones & Pierre Michael
This guide describes how to make homemade printed circuit boards using a laser printer, photo paper, copper clad board, and some basic chemicals. To design the board and create the layout see the article on PCB Design and Layout.
The overall process flow goes something like this:
You first need to design and layout your board. When designing your board, adhere to the following limitations (recommended values are best for beginners):
|Trace width||10 mil or more||7 mil or less|
|Trace spacing||10 mil or more||7 mil or less|
|Layers||1 layer||2 layers|
|Board size||3×4 inches or less||5×6 inches|
| Copper Clad Board|| Digikey (single sided / double sided)|
Mouser (single sided / double sided)
| 1 oz copper or less recommended
Don't buy “pre-sensitized” boards; they are for
transferring the image photographically.
| Photo Paper||Staples (link)||It is critical that you get this particular brand/model of paper.|
| PCB Etchant Solution||Radioshack (link)||Active ingredient: Ferric Chloride|
| Nail Polish Remover||Local drug store||Active ingredient: Acetone|
| Nylon Abrasive Pad||Local drug store||Do NOT use steel wool|
You will also need access to:
Print the design from a laser printer (NOT ink jet) using the darkest settings and highest resolution (e.g. Quality=Best, Intensity=Darkest, etc…). The goal is to get the greatest amount of toner onto the photo paper. Also, be sure to select “Photo Paper” or “Glossy Paper” as the paper type.
Now cut out the design around the boarder leaving about 1/8” of extra paper on three sides and 1” of extra paper on the fourth side (to grab it by).
First, you must prepare the copper board. Scrub the board with the nylon abrasive pad in two orthogonal directions (up-and-down then side-to-side). Use a lighter pass at the end so the board is not too rough. Next, clean the board with a paper towel soaked with acetone until no more discoloration is seen on the paper towel. Press firmly and continue to use fresh parts of the paper towel.
Place the copper board on a flat, heat-resistant surface such as the back of wood cutting board and align the printed design face down on the copper board. Now use a clothes iron (maximum heat, no steam) to apply firm pressure to the back of the photo paper. Hold firmly like this for about 30 seconds. Now that the paper is stuck and there is no risk of slipping, go over the whole board with the tip of the iron, keeping the iron flat but torquing it forward. This should help get the toner to really stick to the copper. The whole ironing process should last about 3 minutes.
Within about a minute of ironing the design on the board, you need to place the board in HOT soapy water. You can heat up some water on the stove if you your faucet water does not get hot enough. Let the paper soak for at least 20 minutes – an hour is even better. You can peel off a little at a time, but if you encounter resistance stop and let the board soak longer.
If some paper residue remains on the board, use your thumb and the hot, soapy water to rub it off.
Mix a solution of 1 part water, 1 part etchant (ferric chloride) in a flat, shallow dish. Place the copper board face up in the dish so that it is just covered by a layer of the chemical solution. Closely monitor the progress over the next 20 minutes or so as the copper is etched away. Here are some ways to speed up the process:
Be careful not to over etch the board or your traces will begin to eat away from the side. If the whole board is etched (translucent looking) except for some stubborn spots, pull the board out of the solution and attack those spots individually. A Q-tip dipped in fully concentrated ferric chloride works well for this.
Use the acetone and a paper towel to rub off the toner from all the pads and traces. Wash the board thoroughly with hot, soapy water when you are done to get rid of the corrosive acetone residue. Now is also a good time to test for shorts and open circuits using the continuity function of your multimeter. Be prepared to do some surgery with a magnifying glass, hobby knife (for shorts), and some solder (for open circuits).
Use a 36 mil drill bit for all through-hole components (resistors, DIP packages, headers, etc…). If this is too small for your drill's chuck to grab you can roll some masking tape around the shank of the bit.
See our Soldering Fundamentals page from the BotShop manual for soldering instructions and safety advice.