What you'll need:
- Beamer (I used my acer X1311WH)
- Photoresist PCB (I used Bungard 1.5 mm single layer PCB)
- Developer (Sodium Hydroxide NaOH)
- Etchant (Sodium Persulfate Na2S2O8)
- Safety Gear (goggles, gloves, etc...) Developer and etchant are very corrosive chemicals. BE SAVE!!!
If you try this method with your beamer, please give feedback in the comments wich model you used so i can provide a list of tested/suitable beamers for everyone.
this will be my first instructable. I was working on some some Arduino and ESP8266 projects and the idea to make my own PCBs came to my mind. I already heard of the toner-transfer method and watched some YouTube videos about the process. Then i saw a video about a "cold toner-transfer-method" based on the usage of solvents like acetone and ethanol. As im working at the technical University of Berlin as an phd student, i had access to these chemicals and because we are building circuits with Arduinos and sensors for our projects there too, i started some experiments with this solvent based toner-transfer-method.
The results where ok, but far from perfect. So was thinking about another simple way to make PCBs. At the same time i was working on a SLA 3D printer based on a beamer to cure the resin for the print. The resin hardens because of the uv-radiation emitted by the strong lightbulb in the beamer. I checked our beamer we use for the printer with a spectrometer and i saw that there really was quite some uv radiaton contained. It wasn't that much but i could find wavelengths down to 380 nm. During my resarch about DIY PCB production i've read about those photo-resist PCB wich are developed with UV-lamps and circuit layouts printed on transparency film. So i was wondering if i could use just a beamer to simply project the circuit layout onto the PCB and skip all the other steps. I checked the internet but i couldn't find any information about this. So the next day i bought some photo-resist PCB at the nearby electronic store and some futher equipment (like the developer (NaOH) and some etchant) and gave it a shot in my kitchen.
Step 1: Setup
I just used a raspberry pi plugged into my beamer. I went online and downloaded a random b/w picture of a PCB layout. I positioned my beamer as close as possible to the wall but still maintaining a sharp projection of the screen. After that i opened the raspian imageviewer an loaded the layout. Then i put the PCB with its protective layer still attached in front of the beamer an adjusted the image to fit the size of the PCB. Thereafter i removed the protective layer and let the PCB sit there for approx 10 minutes, to see if anything happens at all. Then i submerged the PCB into the developer solution and the layout showed up! But unfortunatly it dissapeared again some seconds later. The PCB was overexposed was my conclusion, because the black of a Beamer is not fully black, there is still some light shining through. So i had to get the timing right. I took a new PCB and held one corner of it in front of the beamer again but just for 5 seconds this time. Put it again into the developer and nothing happend. So i increased the exposure time bit by bit and finally found 70 seconds to be the perfect timing for my setup. So i was ready for the first testrun...
Step 2: The 1st Testrun
As before i removed the protection and i taped the PCB to the wall in front of the beamer, at that time the beamer was blocked by some object i found in my kitchen. Then i used the stopwatch of my smartphone and removed the object in front of the beamer for exactly 70 seconds. After that i put the pcb into the developer again, the layout showed up and it stayed this time!
So i got the etchant solution ready and started etching. The PCB turned out beautifully, as you can see on the picture above. The solution turnes turquoise while the copper gets dissolved. The pictures above are showing the etching (there is still some copper left), the finished PCB and a close up.
Everything went really fast. The exposure is done in minutes, the developing also takes just a few minutes only the etching took some time. I guess had to wait about 15 minutes until everything was etched completly, but i jused very basic equiptment. I put the container into hot water to keep the etchant as close as possible to the 50 °C mentioned on the package. So overall my first attempt took me around half an hour i would guess, wich is not bad at all compared to other methods.
Bt if you do this more often with better equiptment you could produce your Prototypes in much less time.
I was thinking about bulding a holder for the beamer out of two pieces of wood with some positioning grooves for the PCB. So you know the size of the projection and you can calibrate everything so you get the dimensions right.
I want to try to make my own layouts with KiCad for my solar-powered-irrigation-system on my balkony and turn them into PCBs with this method.
I hope this helps some of you guys by making your own PCBs!
Thanks to all the other people sharing their experiences on the internet, i use your tutorials a lot when building stuff at home!