As Adam posted, the epson ink is dye based instead of pigment based,
and the epson transparency has a smooth coating that absorbs the ink,
which stops the pin-hole effect. The epson ink and transparency costs
a bit, but it's the combination i found that works the best.
To make it last, i first print the pcb in low-res economy mode onto
some scrap paper, then sticky tape a cut-out piece of transparency
over it, then feed thru the printer to print in high-res mode.
That makes the pack of transparency last a long time. The ink
costs a bit, so i've got two printers the same (epson stylus 400
colour are $50 or less in trading posts). One has the genuine
ink and is used just for pcbs, so the ink lasts a lot longer.
The other printer just has cheapy refill ink for everything
else like printing schematics.
If you do large boards with lots of ground planes, using negative
printouts and resist would save ink too.
Randy Knutson wrote:
>
> Rusell:
> I have a few questions for you, I am attempting something similar to what Bill is doing and I was wondering what types of transparencies you use. I have an HP printer and 3m transparencies but whenever i try and print a circuit it is not nearly opaque enough. There are thousands of tiny little dots where it should be 'perfectly black'. In the past I have alleviated this problem by printing the circuit on three different transparencies and stacking them. This works but not very well. Any advice would greatly be appreciated!
> Thanks!
> Randy Knutson
> Russell <rjshaw@...> wrote: brainlessbill wrote:
> >
> > Hello All,
> > I'm new to the group, and still a beginner at homebrew PCBs, so I'll
> > introduce myself by hammering you all with a tough one (for me,
> > anyways). I recently bought a couple of LCDs with Horz-Bottom SMD
> > connectors (I should have read the not-so-fine print). The pins
> > are .2mm wide on .5mm centers. Does anyone have a technique to etch
> > these fine traces? So far I have only tried photoetching using
> > transparencies and my Brother HL1240 printer, which leaves a few
> > pinholes that I can't fill in. Also, the ferric chloride seems to
> > undercut some of the resist that does remain after exposure.
> >
> > Any pointers would be appreciated. I had planned on using the LCDs
> > for debug readouts for a PCB mill that I am building.
>
> There's plenty of info in previous messages about getting
> sharp 0.2mm traces using epson inkjet printers and transparencies.
> I've done 240pin pqfp chips with 0.5mm lead spacing like that.