This is an alternative method for the etching of PCB's .Its a lot different from the other methods where we use ferric chloride or else hydrogen peroxide.
In this method we use the PCB to be etched with salt water solution and also another electrode made of copper for the etching.
The steps for the etching is as follows:
- Prepare a saturated salt solution with water in a plastic or glass container.[ Its just adding salt to water to such an extent that the salt stops dissolving in the water.
- Prepare a power supply for the process. I would recommend a 12V DC supply or else a variable power supply such that the voltage be controllable. Also add a 750mA fuse just for protection.
- Connect the negative of the supply to an copper electrode and dip it in the salt water solution. In the below photos I have used another copper clad laminate as an electrode which is feasible.
- Connect the positive of the supply to the PCB to be etched. Make sure the terminal is connected to a path which goes all round the PCB such as a ground. I have soldered the power terminal to the board. Now dip this solution into the salt water. Make sure that both these connectors are far away from each others. The PCB is to be made ready after the printing of the resist and cleaning the board.
- Turn on the power supply and you can see small bubbles from the electrodes. Keep checking in between to notice the status of it. Once the etching is done , clean the board off the resist, drill and use it.
Have attached the pics and their description below
My test board, i just signed on it using a marker. Also the supply terminal is soldered.
This is just after the connection of the terminals of the power supply.
We can see the bubbles rising from the electrodes.
I used a 12V battery for the process, pic of the setup
After a while of the process, the solution turns to bluish green colour with smell of chlorine
