Homebrew PCBs

On Thu, 11 Jan 2007 16:58:19 +0100, Dan Pickard <dlpwebmail@...>  
wrote:

> 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


Hi,

You can actually buy metal-tipped plotter pens. Even with carbide tips.  
They have a little spring-loaded wire sitting inside the thin tube. Some  
also have X shaped grooves on the end to aid in inkflow. I got them from  
ebay.

I tried them with a plotter and staedtler red ink but it would not hold up.


ST