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

Hi all,

Has anyone here looked seriously at the use of conductive and insulating
inks in an inkjet printer?

I'm doing PCBs now which are more and more needing 2 or more layers, and
facing the choice of building up PTH equipment or soldering wires
through vias, neither of which are particularly appealing.

It occurred to me that it might be worth looking into the possibility of
a colour inkjet printer with a conductive ink in one of its CMY tanks,
and an effective insulating ink in another tank.

Then, a PCB of n layers could be printed onto a thin substrate (eg
inkjet gloss paper) which could then be glued to blank fibreglass, as
follows:
- one pass with conductive ink, to print all the pads as well as a
first layer of traces
- one pass with insulating ink, to cover the areas of the
previous conductive printing that will be covered by the next
conductive layer
- second layer of conductive ink
- second pass of insulating ink, to prepare for the 3rd layer of
conductive ink
- ...

The challenges I see with this are:

- finding an affordable, highly conductive ink with particles fine
enough to pass through the inkjet nozzles, and print without errors,
and without clogging the nozzles

- finding a good insulating ink that will get enough coverage of enough
thickness to avoid shorts or other electrically undesirable effects

- converting n-layer PCB artwork files into a set of alternating layers
of conductive and insulating ink

- ensuring accurate registration of the substrate through n passes
through the printer - rotational error would need to be pretty much
zilch, x and y errors would need to be around 4mil or less

Anyone got any thoughts on this?

Cheers
David