Clean the glass very well using glass cleaner and a lint free cloth. Inspect the glass for scratches and defects. A small scratch can cause issues when exposing so make sure there are none.
Clean any dust off the artwork. We will not be discussing how to create the circuit art in this article. I simply use a high quality laser printer and good transparencies. Print the image on the transparency so that it will lay toner side down against the copper. This will ensure that no light can leak under the toner.
The photo sensitive circuit boards will (should) be stored in a thick black bag or container. In a dark room remove one panel from the bag and seal the bag back up to protect the other panels from exposure. Remove the protective plastic film that covers the photo reactive coating.
Sandwich the circuit board and artwork between the pieces of glass. One piece of glass is laid directly on the table, the circuit board is placed copper side up on the glass, artwork is then placed toner side down onto the circuit board and finally the second piece of glass is laid on top. Remember this work must still be in darkroom conditions.
Turn on the UV light source and ensure every bulb is turned on and providing even light.
Put the UV lights in position to expose the circuit board. Ensure the electrical cords and other potential obstacles are not between the light and the circuit board since a shadow can cause exposure issues. The exposure time will depend on the type of coating your board has.
After the exposure time has elapsed lift the UV light assembly off the circuit board and remove the top glass.
Slowly peal off the artwork, depending on the type of coating you might be able to see a noticeable difference between exposed and unexposed areas of the board. For example with this type of coating the exposed areas show up as dark purple. Just a note that this is still needed to be done in darkroom conditions.
Some hints that make this process even easier:
a) Leave as much copper as possible in the blank spaces of your PCB designs so there’s not as much surface area to etch. The etching process won’t take as long this way!
b) I’ve had great results by exposing boards with regular fluro lights held a few inches above the glass. You could probably even use sunlight, as I’ve found it many, many times more effective than special uv bulbs when exposing things like silkscreening frames.
c) Float your tray of ferric chloride in a tray of warm water and agitate the etchant with a popsicle stick…the board will etch faster. You can reuse ferric chloride too.
d) Forget Draino! Nail polish remover on a cotton makeup pad works too, and is less dangerous to work with.
e) Cutting fibreglass can expose your lungs to crappy dust. Wear a mask!
Rad Guy – to add more specifics…
A.) If you use Eagle Cad – you can do a copper pour – basicallt draw a polygon around the board and connect it to ground on the PCB designer. Of course there might be some space that might not get filled in and you can do that by hand on the PCB software.
B.) I’ve never used UV (black light) bulbs and just used the drafter bulbs – has a bit of a blue tint.
C.) I use a verticle setup so I can use a bubbler to agitate the solution.
D.) Never heard of that one before – but will try it next time I do a board!
C.) Don’t go cheap on the boards – Fiberglass vs. that other crap.. Fiberglass boards or more expensive – but well worth it if you have to cut.
Great comments. I know what you mean about being dusty when cutting the panels…
I will have to look into those fluro bulbs, how much quicker are they?
I also prefer fiberglass boards, those brown ones seem so brittle.
when you’re done etching your board and want to make it more resistant to the environment, moisture, high voltage isolation etc., consider applying a special electronics coating such as that found here:
SLentions: Epoxy will help that if you are worried about enviro problem. Will be better than the spray – just dip the board once you are done soldering. If you have heat sinks on the board – you will want watch out for that..
Of course you can put the circut in a mineral oil bath!
Thank you very much for your suggestions on “Photoetching”.
I was looking for something like this for the past 2 days. Thank you once again.
I have one question for you. Is is possible to use a simple copper clad board and then coat it
with a photoresist material, instead of using a readymade photoresist board?
Sir, please give me a response as soon as possible.
@Arun.R from what I have heard – the diy photoresist isn’t all that great to use since you have to apply it by hand and it’s uneven with the coating. Get the pre-done stuff. Or just use the laser transfer method if you are not looking to do anthing with a super fine dpi (pitch for SMD stuff)
Of course, I’m looking at the Sears CNC machine to see if it cut it (pun intended) for quicker PCB that don’t have to use chemicals. I would post a link – but it looks like Sears got rid of it with in the past couple days. I don’t know why. They fly off the shelf like free cookies!
[…] If you are wanting to make circuit boards using the UV exposure method you may want to recycle an old scanner into your UV light source. “I opted for 3 tubes (around 8 Euro each), with ballasts and starters (6/7 Euro for each set). The switch, fuse holder and mains socket I scavenged from somewhere. For the bottom plane I used a tin sheet. This acts as a sort of mirror/diffuser for UVs. I used also some scrap aluminum bars from kitchen furnitures, their colour in the pictures tell it. Spacers and screws as required. […]
Great article, thank you! Do you think this technique for this sheets of stainless steel? I need to make intricate gas flow fields for hydrogen fuel cell experimentation. The etched areas, would need to be 1-2mm deep. Here is a link of a commercially made product that gives you an idea of what I’m looking to do. http://www.tech-etch.com/photoetch/images/fuelcells.jpg
A photo sensitive circuit board is a normal copper clad board that is coated with a resist (material that prevents etching). This resist is exposed to light to harden it, the non exposed resist is washed away to expose the copper. The board is then etched as usual.
How much cool water do you use when diluting the Liquid Drano?
I got a board from Far Circuits and no instructions.
Sodium bicarbonate (baking soda)is used for the developer and
Liquid Drano for striping.Thanks
Great article. You may also be able to use an eprom eraser for exposing the boards. I’ve got one, and as long as the board to be exposed isn’t too big, it should work (I’ve yet to try it, but need to do some boards in the next week or so). If it’s powerful enough to erase a chip, it should do just fine on exposing a board. I’ll post another reply when I found out how it works out.
It sounds very easy to start up but never tried it. Are the materials expensive and could you give me some sites or addresses for the chemicals and boards. Fascinated by the scanner conversion, as they always say neccessity is the mother of invention. Can this be done at home ie in the kitchen and what do you do with the waste.
Radio Shack may still carry the etching solution, which might run you $6-$10 on a small bottle. I bought a big bottle (1 gallon) for like $19 at Fry’s Electronics. You can also get the powder which you would have to mix on your own. So I would Google Ferric Chloride and see what prices you come up with.
“The solution must not be put down the drain because of residual copper ions left in it. To make it safe for disposal, you can add sodium carbonate (washing soda) or sodium hydroxide to it to neutralize it, until the pH value goes up to between 7.0 and 8.0, testing it with indicator paper. Copper will be deposited as a sludge. Allow the sludge to settle, pour off the liquid, further dilute it with water and then it can be poured down the drain. Collect the sludge in plastic bags and dispose of it as required by your local waste authority.”
Hey, this article has been great for me. i use photo etching to etch silver before they are made into rings. if anyone’s looking for the photosensitive photopolymer film (the plastic stuff that coats the copper and acts as a resist) i bought mine (uk only i think) at sallydyas.com she does massive roles of the stuff, quite cheap, tho remember you need to do it in the dark or under a red light.
this might not be suitable for you guys and your circuit boards but thought you might like to know!!
P.s. does anyone know of a decent brand of transparencys that i can use my laser printer on…my current stuff from WHSmith(uk shop) seems to be kinda sticky and it picks up dust that i can’t get off. Any suggestions would be much appreciated.
[…] dass man Platinen direkt zuhause mit nicht-oxidierbarer Farbe bedrucken könnte. Die Alternativen? Fotografisch beschichten: riesige Materialschlacht mit Fotonegativ auf Kunststofffolie drucken, belichten, entwickeln. Teure […]
[…] They are used to expose a presensititised blank circuit board. Another common method is to use UV tubes. Alfredo has translated it to English as well as he could (English is not his first language). This […]
I’m an artist and would like to find out how I can etch photos onto steel in my studio. What equipment and chemicals do I need to get started, can I buy all from you and how much cost such a set up?
Your help is greatly appreciated,
you can buy photoresist from Idea factory Equipments (P) Ltd,
Sample pack of 100 gms avialble for 400 rs including shipping cost all over India
for further question please ask me directly at firstname.lastname@example.org
[…] the various current methods that are commonly used which are permanent marker, toner transfer, photolithography, isolation milling, UV photoplotting, laser engraving and inkjet. For his method he reverse […]
[…] Drilling holes in PCBs is one of the most boring tasks I have ever done. Positioning the board isn’t the hard part, pulling the drill press lever up and down at a rate that won’t break the fragile tiny drill bit it the thing to watch. This PCB Hole Driller project will solve this issue by allowing you to simply position the board and hit a foot switch. The system will automatically drill a hole at the rate selected. This is sure to get some good mileage out of those fragile drill bits that love to snap. […]
[…] Making your own PCBs boards is a time consuming task. If I need to make 1 or 2 simple boards I don’t mind spending some time and building a few but if you will ever need more than that you better look at getting them made by a professional PCB manufacturer. This means that drawing a picture of your copper layer in a graphics program and printing it on a transparency won’t exactly cut it since all of the PCB manufacturers will need Gerber and Excellon files. But with these files they can work their magic. […]