How to Etch a Printed Circuit Board

The first question that I can hear u thinking is what’;s a PCB? PCB stands for Printed Circuit Board, for example your motherboard is one big PCB (just multilayered) obviously a motherboard is way out of our league, however with some household equipment and some chemicals we can make ourselves some great casemodding PCB’;s. Just think of fading LED’;s, homemade fan controllers, and anything else you can come up with. In this guide I’;m going to explain how to make a usable PCB. With this step by step guide you can make you own in no time, here’;s a list of things that will be needed.

 

 

Plastic Tweezer

 

 

Disclaimer: The information contained in this site is for guidance only. The application of this tutorial can differ extensively based on the particular items involved. The information on this site is provided with the understanding that the author(s) and publisher(s) are cannot be held legally responsible for any injury or death that may result from this or any other article at OCmodshop. With this being said be sure to understand what you are doing before you attempt what is being shown. If you have any questions about any aspect of the article please contact the author or another experienced individual before proceeding.

• A sheet of printable transparent film (for overhead projector usage)
• 2 plastic or glass containers to hold the liquids.
• Plastic tweezers
• 0.8mm, 1mm, and 1.5mm drill bits
• Water
• Acetone, or nail polish remover (contains acetone)
• A face toner, or any other UV-A light source
• A blank PCB with UV photo layer
• Some Hydrogen Peroxide (35% concentration but lower is also good)
• Some Hydrochloric Acid (10 % concentration)
• Caustic soda, which is also referred to as Sodium Hydroxide.

The first thing we need is a design of what you want to make. There are all kinds of programs for that and you can even do it by hand. I’;m using the program called EAGLE, you can find it

Protective Layer Art on the photosensitive layer

From here on begins the actual Etching process. The board itself is made of multiple layers of glass fiber, also known as an epoxy board. First measure what size board you need and saw it off using a hacksaw. The blue plastic layer is the protection layer of the copper and photosensitive layer. If you damage the board don’;t use it because it will turn out bad. Don’;t remove the plastic layer until the very last moment when where going to expose it to the UV light. Remove the protective layer, and place your printout the way you want it, and again take notice that it’;s mirrored.

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

 

 

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” ;)

 

 

 

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.

So you made it to the first few steps, well its easy going from here on. Time to break out the chemicals, please refer to the first page for the list of stuff needed, you can get those chemicals at your pharmacy or chemical store. There are few more ways to etch a PCB, but this is the only one where you do not need to heat the liquid, so no need to buy expensive equipment to do that.

When making a cold etching bath, please be careful dealing with chemicals, even though these aren’;t the strongest around they will leave nasty irremovable stains on your clothing. remember you only have one set of eye’;s and limbs, they don’;t grow back, so wear protection! When dealing with chemicals wear rubber gloves and safety glasses. If u happen to spill some solution on your hands rinse it with water immediately, and if a white spot develops on your skin, simply cover the spot with a thick layer of moisturizing hand cream.

Right now, get a little plastic container or glass bowl and add about 3 to 4 bottle caps of Hydrochloric Acid (10%). To the Hydrochloric Acid we need to add the Hydrogen Peroxide, put about 1 to 1.5 bottle caps into the bowl, and stir with your plastic tweezers to properly mix the two chemicals. You have now just made your own cold etching bath, wasn’;t that hard was it ;).

 

 

Etching in progress

 

 

There are a few things you need to know, when Hydrogen Peroxide is mixed with an acid it will react with it. The reaction will not be harmful tough, all you get is pure oxygen. This process will continue until the Hydrogen Peroxide is gone, leaving you with the water it contained. By doing this the Hydrochloric acid will lose its strength because its slowly getting diluted with water. If the etching goes really slow add some more Hydrogen Peroxide and if that doesn’;t help, you will need some new Hydrochloric acid. You can store the solution in a plastic coke bottle or a glass jar, but don’;t fully close the lid because the pressure will build up and your bottle or jar could explode, the best way to prevent this from happening is to puncture the cap or lid with a nail, so the buildup air can escape.

Now get your developed board and place it in the solution, be sure the whole board is submerged. You will notice that it will fizzling a lot, this is due to the chemical reaction the mixture has on the copper. Continue wiggling the board every so often, for approximately 1 to 5 minutes.

 

Particaly Etched

After about 1 or 2 minutes you’;ll notice that you can see some board through the copper. Frequently check until all of it is gone, when your artwork is clean and clearly visible get it out of the bowl and rinse it with water. Remember we don’;t want to leave it in the solution for too long or it will begin dissolving the protected copper. Congratulations, you just made your own Printed Circuit Board.

There are only two things left to do; first you need to remove the photo layer that’;s still on the copper. Just use some nail polish remover or acetone to remove that layer, when you’;re done the copper should look shinier. Now just drill the holes you need, you can do this with a engraving tool, Dremel, or drill. The most common sizes of drill bits used in PCB’;s are 0.8mm 1mm and 1.5mm so use the right sized bit for the hole you need.

 

 

 

 

You can leave the PCB clear but it can corrode without any protection, to prevent this apply a soldering agent called flux which you can get this at the local electronics store. When you are finished you can begin placing the components and start soldering.

I hope you’;ve learned from my guide and that you succeeded in making a PCB. And in order to make everything just a bit easier, I’;ve also created a movie so you have a little moving guide to see how the steps go, you can get the movie in 2 flavors.

 

 

 

Video File	File Size	Video Format
High quality	28MB	Windows Media 9
Low quality	7MB	Windows Media 9