Homebrew PCBs

At 03:02 PM 5/17/2010, you wrote:
>Hi Mark,
>I've been following a similar path, but with the 
>Xerox/Tektronix Phaser solid wax ink printers.
>I have a 8400 and an 850D that I run 8mil thick 
>flexible single sided stock in the manual feed path.
>It works well to a point, except sometimes I 
>have to preheat the board going in.
>
>It's been hit and miss as I think I've been 
>running into electrostatic issues similar to what you've
>been working through.
>
>I'm going to try the Carbomer/alcohol/water 
>shared by David yahoo@... (www.laserpcb.com),
>1 cup water, 1 cup isopropyl alchohol, 4 tablespoons Carbomer 940
>
>To see if that helps bring the line resolution down.
>---------------------------------------------


I'm pretty sure what Dave's gel does is help the 
powered toner stick to the board as it passed 
through the fuser. He uses it in an intact laser 
printer on copper foil, not copper clad board.




>***Your toner method has really good advantages 
>that are leading me to abandon the solid wax printers:
>
>1) Your line resolution looks better.


I suspect the resolution of this process is a 
function of the resolution of the laser printer 
and the etching process. Thin traces (3 mil) are 
easy, but 3 mil traces with 3 mil spaces between 
them is not so easy. That's where the ability to 
decrease the toner density comes in handy. Using 
the toner density at maximum (via the E260 
utility program) makes it easy to get dense 
lines, but there really is too much toner if you 
want the lines close together. For that you have 
to back the density to about half (5 out of 10). 
Then you have to be able to fuse it without skips 
or smudging. Dave's gel certainly might be useful here.



>2) If the transfer has issues, your method is 
>much easier to dust off clean and redo. I have to strip the wax off & re-clean.
>
>I have a E260DN ready to do your modifications( 
>You do very impressive-creative work, process, and docs!! )
>-Bought a small lab supply 0-10kv for experimenting just in case.
>
>Questions:
>1)I had a question about your instruction/comment below:
>"Interestingly, using an un-coated aluminum carrier will not work ­
>it seems to require much less transfer voltage!"
>
>Sorry if I sound dense, but does this mean "the 
>coated carrier makes it require much less transfer voltage"



Oddly, it means exacly what it says. A coated 
aluminum carrier works perfectly with either a ds 
or ss pcb taped on top of it with ky between the 
carrier and board. The internal hv transfer 
voltage (as measured with my Fluke HV probe) is 
about 1600 volts. If I use a plain piece of 
aluminum as a carrier, the required voltage seems 
to be MUCH less. Unfortunately, by the time I did 
that experiment I had removed the external 
supply, but I can tell from the horribly 
distorted image that the voltage is way too high.





>2) It seems as if the carrier and the PCB with 
>the help of the KY make a simple capacitor
>between the carrier's( expoxy insulated) inner plate
>and the PCB surface. I was wondering if some of the
>KY is conductive somewhat, and is it touching/bridging to the PCB surface
>copper. Just curious on what you think?




The ky is mildly conductive, but I don't think it 
is bridging the sides of the board. In the past I 
experimented with soldering copper foil across 
the sides and it seemed to make no difference.


Good luck to you - let me know how things work for you.

Mark




>Thanks,
>-Lee
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