Homebrew PCBs

Stefan - here is some basic info on printhead design, for what it is
worth.

https://www.inkzone.com/resource/ptech.cfm

I am wodering if the heat in your print head acted as a catalyst and
the polymers cross linked. That would make a "clog" I think.

A chemist friend who develops plastics for Dupont thought that the
potassium permanganate you probably used acted as a catalyst and
triggered cross-linking. I  will ask him about the heat theory, too,
when I get a chance.

Grant

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> 
> On Sun, 22 Jun 2003 01:13:15 -0000, grantfair2001 <grant.fair@s...> 
> wrote:
> 
> > Hi Stefan-
> >
> > I was wondering about why your experiment failed. Some acrylic floor
> > floor polishes have a particle size of 185 nano meters. Some inkjet
> > print heads can handle particles of 750 nano meters diameter. So I
> > wonder what made the print heads clog? I guess that particle density
> > and ink viscosity might be related variables.
> >
> > Does anyone know an inkjet printhead engineer/ink chemist?
> >
> > Grant
> >
> 
> i think you are right.
> also a problem may be that the head i used was a thermal bubble jet.
> this may be the problem because it heats the ink up in the nozzle
and this 
> may help in clogging it up.
> 
> if you remember i also inspected these heads. behind each nozzle i
could 
> find two "electrodes" only seperated a small distance.
> they were both in the pipe through the head material (silicone?),
located 
> just under the golden cover foil.
> 
> i could not see any "resistor" element in there. so i had the following 
> idea:
> hp may use the ink as a "resistor". i know this would have some 
> disadvantages but also some advantages:
> the ink kinds being useful reduced ("buy hp").
> if there is no ink in there, if it is clogged before the head it
will dry 
> up and heat no more.
> 
> i have no idea if this is true. if anyone has the right optical
tools he 
> might inspect a dead head closer by himself.
> 
> 
> i gave up so sudden because of the following:
> 
> if only one single jet is clogged you get a gap all overthe tracks
on the 
> pcb, and this every 5mm or so.
> i didn't like this idea.
> 
> 
> but the head worked with water, and as i put in the polish not one drop 
> came through the head anymore.
> maybe i try again if i get a really cheap piezo inkjet.
> 
> 
> regards
> stefan