One must not get hung up on a project, instead of a goal.  In this case,
the goal is to produce PCBs faster and cheaper than a commercial board
house, and we're specifically looking at inkjet printers because:

Potential advantages of Inkjet printers for PCB fabrication
-----------------------------------------------------------
1) Inkjets are cheap, widely available, and widely supported.
2) Inkjets are good (relatively speaking) at "filling in" large print areas.
3) Inkjets are fast, printing a full 8x10 page in a couple of minutes, even
   with large filled areas.
4) Inkjet mechanics are relatively simple and potentially easy to modify.
5) Ink cartridges are potentially refillable with all manner of exotic
   concoctions.
5) "instant" output.


On the flip side, you also need to remember the disadvantages of this
scheme, compared to a commercial board house:

Disadvanatges of inkjet technology:
1) inkjet cartridges are typically rather expensive.
2) inks modifed for PCB resist may be hard on inkjet mechanisms (clogging,
   solvent efect on plastic parts, etc.)
3) (consumer) inkjet technogy is designed for absorbent media.
4) The further you move from off-the-shelf inkjet technology, the less
   desirable the option looks.  You don't want to have to prepare special
   ink, clean your ink paths, coat your board with an absorbant or
   chemically active layer, etc, etc for each board you "print."
5) printing chemical resist direct to the PCB only eliminates a couple of
   the steps in typical home PCB fabrication (photocoat, expose, develop),
   and they're not the most obnoxious steps.  You still need to etch and
   drill, for instance.

Advantages of commercial board house:
1) holes drilled
2) Plated through holes
3) soldermask
4) silkscreen (for single sided boards, you can replace silkscreen with
   inkjet-printed lable-stock, sort of.)
5) tinplate


(hmm.  Here's another idea.  The typical commercial board maker seems to use
a photoresist that goes away where tracks are desired, then tin plates, then
removes all photoreists and etches using the tin plate as resist.  This
raises the possibility of using something like an electroless tin plate
solution in your inkjet cartridge - it doesn't NEED to dry anymore, just so
long as it deposits enough tin before being washed.)

BillW

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