In my fourth semester, my group mates and I had to make two mini projects. Our topics that we choose were “a twilight” switch and “A heat sensor with fan cooling”. After buying the components, we had to etch the copper clad board. Instead of connecting the components with wires, we trace a path on a copper clad board and etch(which I am going to explain), then drill holes for the components to be mounted and then solder with a soldering gun.
For PCB etching, you need:
- A copper clad (Available at any store that sells electronic components, I got mine from Lamington road for Rupees 10 )
- A permanent ultra fine OHP/DVD marker. (I used a cello permanent ultra fine OHP/DVD marker, Rupees 15 )
- A ruler
- an eraser
- A pencil
- Ferrous chloride powder. (75 grams for Rupees 25)
- 100 ml water
- tracing paperw
- A tray or a broad container of 5 cm in height and as for width and length: just enough so that your copper clad board can fit.
- cotton ball
- acetone (Nail polish remover)
- rubber gloves
Trace the path perfectly, use the grid that you made. Be as perfect as you can. The path traced should be approximately 3mm-5mm thick. Don’t worry, if you make mistakes, you can erase them.
After your done and happy with the path that you have traced, draw it again using your permanent marker. It should look like this.
Add 50 grams ferrous chloride to 100ml water in your plastic container or tray and place the tray near your window where the container/tray is exposed to sunlight. Don’t panic when you hear “whoosh”, its an exothermic reaction. Your etchant is ready!
Put in your copper clad board, with the path you traced facing you. And wait for 30 seconds, you will see bubbles on your board. Shake your container/tray horizontally, but not vigorously for about 3-5 seconds.
You will see some of the copper dissolving. After about 30 seconds, shake it again.
At intervals of thirty seconds, shake for 3seconds till the copper dissolves and you are only left with the path traced by you. This should take around 8 to 10 minutes. Make sure your around while your etching, and don’t leave it in for more than 15 minutes.
Remove your board with your rubber gloves on quickly, and pour drinking water over it. And this is what you get.
Put some acetone on a cotton ball, and use it to wipe off the permanent marker ink. You are left with copper that you have traced! And you’re done!
Drill holes in the places that you’re supposed to, mount your components and solder.
And you’re done!
Walter C bosshart: PRINTED CIRCUIT BOARDS, Design and Technology, Publication Tata McGraw-Hill publishing company Limited (24th reprint 2002), Regensdorf, Switzerland.