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It has been many years since we made an article on our Photo Etch Circuit Board Process. Next time I make some boards I will definitely use hydrogen peroxide and muriatic acid as by copper etchant. I have been using ferric chloride for many years but it is very messy and is quite expensive. In the video above Daniele Nicolucci shows a nice step by step process of making a DIY Photo Etching PCB. He uses a transparency just as we do to use as the mask when exposing the photo sensitive copper clad board but I was surprised to see that he preferred to use his inkjet printer output instead of his laser printer output. I have always got better results using my laser printer. |
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May 30th, 2010
Wow, very detailed video. I’ve used the HCl + H2O2 technique for a long time, but I realized that the green stuff that is formed in the etching bath is itself an etchant, and can be reused. I’ve now stopped throwing environmentally unsafe Cu ions down the drain
All details on this site :
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
A few tips regarding the general process :
* During exposure the film must be very close to the board. Make sure to print such that the ink is touching the board. To ensure good contact, I put the board+transparency in a transparent plastic bag and make a vacuum. I made a small vacuum pump using a modified aquarium pump. I’m pretty sure there is an instructable explaining this.
* The development is quite critical, the concentration of NaOH must not be too high or non-exposed photoresist will be dissolved too. I suggest to use store-bought powder to dissolve in water. Costs less than 2€ and can be reused many times.
* Try SMD components. The bigger ones are quite easy to solder and you don’t have to drill any holes
May 31st, 2010
I agree with all of vic’s points, especially about printing so that the ink touches the PCB to get the cleanest exposure. I use a cheap photo ‘frame’ (glass, backing, clips that hold it together) to secure the mask to the PCB, but the vacuum packing idea sounds really interesting.
I’ve done the opposite of Alan, I’ve always done UV boards with inkjet and never laser. Nothing against it, I just never have access to a laser printer when I need it. With black-only prints I need two layers to get a decent exposure, but using a mix of colors and black (called high-quality black mode on my printer) gives a nice UV resistant print that works in a single layer. I once did an experiment to see which color was best, but no single ink outperformed the mixture. I’d like to have an ink refill place fill a whole cart. set with special uv resistant ‘photo’ ink and see if that is an even better option.
May 31st, 2010
One hint for disposal of etching fluid.
In germany, we have certain places, where we can bring toxic chemicals for safe disposal mostly at very low costs, or even no cost.
I think a bit of googling will reveal such places near you.
June 1st, 2010
No need to stick the mask down like that, i just lay the board down and put a plane of glass on top. The transparent sheets only need a little pressure to hold it against the board.
And i use ferric chloride to etch my boards, its not as fast but needs no mixing and makes no fumes. A mask wont protect you from the fumes btw, i used a fume hood when working with the hydrochloric acid as the fumes are very bad. Altho i use none of the safety gear and i even sometimes pick the board of of the acid with my fingers, but if you do touch the acid make sure you wash your hands in the next half of the minute or it will start to eat your skin.
June 1st, 2010
I’ve had great success with inkjet as well — as soon as I stopped trying to use clear transparencies.
Out of curiousity I tried printing the artwork on photo paper and using that to expose the board, and the results were fantastic. I use an 8 minute sunlight exposure on a MG Chemicals positive sensitized board, with the artwork printed on an Epson Artisan 50 printer at max resolution, etched with sodium persulphate. 12 mil traces are trivial, and I can do 8 comfortably and sub-8 mils if I am willing to take a hit on yield or watch the board like a hawk.
I echo the use SMDs. Originally I did board with mechanical etch, and went with all SMD (including header connectors, etc) to minimize tool changes — which turned out to make photo-etch PCBs super easy when I moved to the photo process.
June 4th, 2010
I would be a little more careful with the drill, slamming it into the board like that could snap the bit and it could take yur eye out!!!
Why not save the developer and etchant for future projects instead of binning it each time?
October 19th, 2010
The trick to getting good results with an inkjet printer and transparencies is to use the right type of ink. Black is usually the worst color to use!
I use GREEN as the mask (HP Tricolor 57 cartridge) and not black because most inkjet photo
cartridges are dye-based and green contains Photo Yellow which is a natural UV
filter plus Photo Cyan which contains a UV inhibitor!
Pure green is half yellow and half cyan when printing in photo mode and it
creates a good UV mask even though it is easier to see through than black.
Just make sure you have a decent photo cartridge and use photographic mode
when printing so that the photo colors get used.