Last night we had our Electronics Workshop #6, where we learned to etch our own PCBs. And while DIY etched PCBs may not approach the quality of boards made at outfits like SeeedStudio, it’s great for making early prototypes as you don’t have to wait weeks. It takes less than 1 hour from printing the layout to having a fully etched board.
Before we get started, do yourself a favour and read these safety tips:
- When dealing with caustic chemicals, please wear appropriate protection (Protective Eyewear, Rubber Gloves)
- Handle chemicals in a well ventilated area
- Use Caution
Board Layout Tips
While it’s totally possible to etch 8 mil traces with small pads, the best results can be achieved with the following tips:
- Wherever possible, follow a 50mil-50mil rule. Traces 50mils in width, and 50mils spacing between traces
- Fatten up those pads. 50mils drill holes, and 75mils diameter.
Etching Solution Recipe
For our etching solution, we decided to forgo using Ferric Chloride, and instead use a solution of Hydrochloric Acid (Muriatic Acid), and Hydrogen Peroxide:
- In a non metallic container, pour 1/2 cup of Hydrogen Peroxide (3%).
- Slowly, pour 1/4 cup of muriatic acid into the Hydrogen Peroxide.
Transferring board layouts to Copper Clad PCB
This is by far the most delicate part of the process. Take your time, and if you’re not satisfied with the results, you can always have a do-over, or two, or three!
- Vigorously clean your copper board with fine steel wool and dry. (Do not touch with fingers).
- Print your board layout on a sheet of glossy paper (you can use old magazines/catalogs).
- Cut the glossy paper to the size of your board layout, but leave some excess to handle.
- Put the printed layout face down on copper board, and put a sheet of normal paper on top.
- With your clothes iron set on the hottest setting (Cotton), apply heat and a lot of pressure, without moving, for 2 minutes.
- Motion the iron around on the board for 5 minutes.
- When the board has cooled, put it in a bath of water.
- Wait a few minutes for the paper to start dissolving, and gently peel the paper away.
- It’s ok to have left-over paper on the mask, but remove any left over paper on the copper.
- Put your board in the etching solution, face up. It should take about 25 minutes to etch properly. Keep an eye on it, to not over etch.
- In the final minutes of the etching process, swirl the container a little, that will help etching in tight spots.