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

Reading Mike's email on PTH (Re: Markus's machine and old posts)
conductive ink, I got to wondering.
I don't think the ink is conductive enough to make reasonable traces in
it's own right., but is printing a conductive ink onto the surface of
FR-4 and plating it a way to make PCBs?
My understanding of how it works for PTH is that you hook the un etched,
but plated, board to either + or - (I don't know which) and the copper
source plate to the other terminal. The original copper plating allows
current to flow either to or from the conductive ink in the hole (as
well as the rest of the copper), and copper is deposited on the
conductive ink and the existing copper plate.
This leads me to believe (with no empirical evidence) that the entire
area to be plated must be electrically connected. To print a conductive
ink onto the surface of the FR4 and plate it, all the traces must be
interconnected. Is that correct?
If you can print thin enough lines, you could interconnect with a
different line width, at the cost of cutting the then plated lines out
later.
Would it reduce the PS current requirements, since there us so much less
area to plate?
If a board coated with the ink is resistive enough to run through a
laser printer and pick up an image, you could print a mask onto the ink
to shield parts of it from the copper plating solution, and you would
only plate the traces. If that worked, you would not have to worry
about the interconnections, since the ink is conductive enough to
support the plating, and the entire board is covered by the ink. After
the plating, you would strip off the toner and the unplated conductive
ink in some manner.
Any ideas as to the feasibility?
Richard