etching – Murli's Blog

Making a printed circuit board (PCB).

First cut the copper clad board to size required.
Sand the surface of the board to remove the layer of copper oxide that is formed due to the reaction of the copper with the oxygen in the air.
Once the copper surface is shiny and clean avoid touching the surface of the copper.
Eaglecad or ORCad may be used to design the schematic and the pcb design .
Take a mirror image of the pcb design while using the CAM processor to generate the Gerber files .
The gerber files maybe viewed online at http://www.circuitpeople.com or the .eps file maybe viewed offline using the .eps viewer take a lazer printout of the pcb layout using. this printout will be the mirror image of the actual pcb layout .
Since during the transfer process the mirror image of the actual image will be transferred.
Now cutout the actual PCB layout on the transperency. this will be the toner transfer
.
Lightly wipe the toner layer of the toner transfer with a peice of cloth and the surface of the cleaned copper clad. This will ensure that there is no dust or grime between the toner surface and the copper.
Place the transfer on top of the cleaned copper clad board.
Secure the layout in place with the help of a peice of tape or some glue.
Using a hot clothes iron heat the toner transfer so that the toner layer from the tranfer is transferred onto the copper.(set the iron to the highest temperature possible…usually the cotton settings)
Iron the transperency gently.
Don’t put too much pressure on the clothes iron else the toner will smudge. too little pressure and the toner wont be transferred at all.
Once you think the toner is stuck to the copper turn off the iron. let it cool down to the ambient temperature.
Peel off the transperency if you got it right then you will see that almost all the toner has been transferred to the copper surface.
The toner layer will form the etch resist.
Now the copper clad can be put into the etching tank. ferric chloride maybe used as the etchant. although muriatic acid maybe used too.
Gently ‘move’ the copper clad board through the FeCl3 solution.
Once all the unwanted copper has been removed clean the PCB under running water.
Remove the layer of the toner with some sand paper or a solvent such as acetone.
If the PCB is meant for surface mount components then the PCB might require drilling.
After the drilling is over. tin the copper surface to protect and increase the conductivity of the copper tracks.