How to Etch a Printed Circuit Board



This step is just as important as the quality of your design; most likely you need to experiment with what the best exposure time with your lamps is. I’;m using an old Philips face toner it contains four (4) 75 watt’;s UV-A tubes, the perfect time for me to expose the photo layer to the UV-A light is 90 seconds. UV-A light is found in tanning apparatuses and the sun, as we all know you can get skin cancer when you’;re exposed to the sun for to long, this is caused by the UV-A radiation we are using that same radiation. Since we’;re for only going to use the lamp for approximately 1 to 5 minutes I think it’;s a safe to say that we won’;t have any complications. Then again if it where harmful the tanning salons would be out of business pretty quick ;)



Face Tanner
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Remember this is a trial and error kind of thing, if you don’;t succeed the first time try again. Don’;t be put down by failures because you’;re going to get them one way or the other, don’;t give up you’;ll get it right in the end! So after exposing the board to the UV-A light for 90 seconds it’;s time to and develop it. Its best to develop it immediately but you can wait as long you want as long as u keep the exposed board away from the sun or any other light source, an envelope is a good storing place. Just like your normal photos you make with your camera, photolayer board also needs some developing. The soul purpose of the photolayer on the board is to protect the copper. In its un-exposed state it’;s solid, and covers the whole board, when you expose it to the UV-A light you soften up the layer and that’;s the magic. While the rest of the board is exposed and making the photolayer soft, the unexposed layer is still hard since we covered it with our “art” ;)


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After developing we need to remove that soft exposed layer, for that where going to use caustic soda, also referred to as Sodium Hydroxide which you can buy this at your local electronics store. Put a good teaspoon full in to some water en stir till all the little white balls are gone and you are left with murky water.

Now get your pair of plastic tweezers and grab the exposed board, dip it in the solution you will see a brown purple glow oozing from the print and your “art” should become visible. In this process wiggle the board around a bit, when all the lines or what ever you made are visible quickly rinse it with some tap water. Congratulations you have developed you first PCB, now give a little sigh of release as the hardest and most crucial part is over.