Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hello people,
I've been trying to use a flat bed plotter and "pens" to fabricate PCBs for some time now. I've come to the conclusion that all ink pens suck for this method. Even the best pen results fail right before the etching is complete, they just don't have enough bonding strength in acid. I love this PCB fabrication method, I just need a pen that will work. I seem to have the best luck with red pens and I know that red dye has the most solids in it. Anyway, In my frustration I decided to try to build a high-resolution paint pen for the plotter. I had my wife bring home some tuberculin syringes with a #25 and #28 needle on them. I cut the needle at the base and polished it with my dremel. I then mounted it in a Roland DXY1100 plotter and filled the syringe via an extra syringe with screen printing ink thinned to right viscosity to produce a drip every 30 seconds or so. This is just the right amount of ink to produce very solid lines with nice heavy ink deposits without
blotting. I was getting at least a 0.025" resolution with #25 needle and should be able to do better with a #28. As for the etching I just put the PCB board in some Muratic acid - persulfate is very slow...., Ferric is OK, and Muratic/peroxide mix is very very fast, almost violent, and I like instant gratification ;-) I was etching in my shop with a ambient of 16F last night so even Muratic etching was very slow. This step was always the 'time of truth' for the pen methods. It always resulted with the ink lifting off the copper just before the PCB was finished etching. I left my new PCB in acid for 40 minutes and no ink left the PCB with no surface degradation of ink also. This will be my new preferred system from now on. I just want to share my results because I'm sure others are trying the same method.
Thanks, Dan


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