Homebrew PCBs

Fri May 26, 2006 3:48pm(PDT), Lez wrote:
>...but what about home made inks with evaporative solvents,
>...what about cellulose thinners, gasoline etc, with a wax, type 'pigment'
>
>Would not such a thing go through the really old hp500 heated bubble
>type printers?

I think the problem may be that it _will_, all too easily, unless you put
a _lot_ of the resist medium (or something else) in it. Water is peculiar
stuff, with a lot higher surface tension and boiling point than it ought to
have in comparison with similar-sized organic molecules. Latent heat
of evaporation for water is also anomalous, so the heater thermal cycle
probably would be more extreme.

So I think there is a fair chance that a wax in light petroleum solution
will either drip through the nozzles or fail to be bubble-ejected with
sufficient force, or possibly both. You might have to establish a very
different working regime for the nozzles, requiring firmware changes.

OTOH it might work - ISTR the old Kodak Diconix ink was of a
rather 'oily' consistency, but (a) it probably was a glycol mix rather
than a petroleum fraction, and (b) it didn't use quite such a fine nozzle.

It might be possible to use a thin solvent-in-water emulsion to get
the best of both worlds but stability can be a problem. Still, we have
suspended pigments so why not emulsified oils?

Wax+petroleum in water+glycol would be an interesting place to start.
A surfactant or ultrasonic agitation would help dispersal and a colloid
would help suspension but what colloid wouldn't contaminate the
heater, I don't know.

Please, no Hellmann's recipes from the goat fraternity :-)

For the fire hazard, options include:
i) _lots_ of ventilation (i.e. fume cupboard or open air - simplest);
ii) _no_ ventilation (sealed enclosure), to work above
  the explosive range (difficult to be sure, esp. at start-up...);
iiii) purge enclosure with inert gas (e.g. CO2, N2 or welding gas).

(Using a water-based emulsion would greatly reduce the fire risk
by reducing the proportion of inflammable solvent.)

I would like it to work but, when I imagine of all you budding
Edisons out there slaving away, I realize we are going to get
a lot more work done through photoresist or TT before you
discover your 2000 ways for it _not_ to work.


Regards, LenW
-- 
   Please trim quotes to minimum for context, then
   reply _below_ or interleave point-by-point replies.
   Give your wisdom the presentation it deserves.