Homebrew PCBs

You guys were complaining about the vapor from acetone - let me tell 
you what not to do!  Two nights ago I tried to hand draw a circuit onto 
a board with silver conductive ink.  That stuff will kick you in the 
trousers!  After a couple of minutes, with a door open and a fan on, I 
wasn't sure I was going to be able to draw straight lines with a ruler. 
 If anyone is as foolish as I was, please buy an organic vapor mask to 
wear!  you don't want to end up with my issues. :)
  Also, you were talking about getting conductive inks in general.  The 
ones I tracked down are mainly silver based, and generally with a heavy 
volatile organics load.  I did have one company (Dow Corning) send me a 
sample - a couple of fluid ounces - of PI-1000 (Solderable Polymeric 
Copper Paste) & PI-2000 (Highly Conductive Silver Ink).  It's wierd, I 
never asked for a sample, but tey sent it.  I have been asking for 
suppliers and costs, but they have not supplied that yet.  I was asking 
about inkjet printing of conductive ink.  The general answer I got was 
that the silver particles in this type of ink are too large for most 
inkjet nozzles.  My experience above lead me to believe that unless it 
was some type of UV or heat cured ink, it will be way to volatile for 
inkjets, and would clog the jets with dryed ink.  The conductive ink I 
was using dried in about a minute - that doesn't sound fast, but it sure 
started globbing within a couple of seconds.  Not the best thing for 
drawing.  I think the curable inks are a must if inkjets are going to be 
used.  There also needs to be an insulating ink.  And while your at it, 
solder mask and component side markings.  I'm not sure how to do a 
through-hole, but then, you don't need to do double sided boards, unless 
you run out of room for surface mount components!  you would want to put 
a final coat on it for durability.  The ink I have (by Caig, from Fry's) 
seems to peel off pretty well.
  I have not touched the Dow Corning ink yet, and if anyone gets to the 
point where they are ready to try printing in a manner that can use it, 
I'll donate some or all, as required, and as capable  The link is 
http://www.dowcorning.com and then searach for conductive inks.  They 
have a bunch, but the PI-1&2k seemed like the best in terms of organic 
vapors, curability and such.  I think they are both heat cured, but 
don't have the data at hand.  It's on their site, if you root around. 
 They are both suitable for screen printing, and the silver paste is 
supposed to be good for flexible circuits.  Only the copper is solderable.
  Now that I'm thinking about it, I may get a vapor mask and try again 
at drawing.  The ink I used was very thin.  The PI-2000 is a paste, 
maybe it will work better out of the syringe then the Gaig stuff did.  A 
drawing fool.
Richard

On Mon, 08 Mar 2004 16:06:43 -0800, Richard Mustakos <rmustakos@...> 
wrote:

>   You guys were complaining about the vapor from acetone - let me tell
> you what not to do!  Two nights ago I tried to hand draw a circuit onto
> a board with silver conductive ink.

I only worked in small quantities with the silver ink.
so i didn't experience your problems. but it is way too expensive
for me...


Your writing about the printing has brought up the following thought:
if you could print a conductive ink and a isolating ink you could easily 
print
multilayer on a "layer by layer" basis, not requiring vias.


ST