After designing the printed circuit board or PCB layout on a computer, the next step is to etch a PCB according to the layout. This etching process can be accomplished in essentially three ways: with a laser, with a mechanical engraver or with chemicals. The first two methods require expensive machines and are used only when high precision is required. The chemical method is the most common one and can be mastered with some practice. It is worth mentioning that chemical etching can also yield results that are comparable to high-precision laser etching and therefore it is also used for mass producing PCBs.
Instructions
1 Print the PCB layout on a piece of parchment paper using laser printer. For this you can use the print function of the PCB design software you are using.
2 Place the PCB print upside down on the PCB and tape it securely from the sides using masking tape. If the board has only one side of copper sheet, the paper must be placed on that side. If there are bubbles between the paper and the board, gently swipe the paper with your hand to remove those.
3 Place the board in the UV bath and turn it on. Wait for about three minutes and turn off the UV bath. Some UV baths also come with timers, which automatically shut them off after the preset time. Wait for two minutes before taking the board out of the UV bath. Take the paper off the board and store it in a safe and dry place for possible future use.
4 Wear the safety glasses and rubber gloves. Pour the NaOH and ferric chloride solutions in separate trays to about a height of 2 inches.
5 Place the PCB in the NaOH for one to two minutes. Take it out and wash it in the sink under tap water. You can use a soft brush to clean it as well. If the traces are not clearly visible, put it back in the NaOH solution for a couple more minutes, then take it out and wash it again with water.
6 Put the PCB in the ferric chloride solution for about an hour and a half. Take it out and wash it in sink with tap water. Your PCB mask has been inverted on the PCB.
