On Nov 25, 2008, at 7:06 PM, Brendan Moran wrote:

> The broad requirements for the material are these:
> 1. Must be printable, that is it must be possible to load a syringe up
> with the material, squeeze it out onto the substrate, and let it cure.
> Two-part compounds would be alright provided that a mechanism for
> clearing the print nozzle is practical.
> 2. Must be conductive, at least as conductive as gold (Ag>Cu>Al>Au)
> 3. Must be readily available, this material should be something that  
> can
> be made easily or purchased easily.  Ideally, I'd like it to be less
> expensive than conductive epoxy. ($26 for 6mL seems pricey to me)
> 4. Must not require high temperature baking (>150C)
> 5. Should not require lengthy cure time, this will slow fabing
> significantly on complex parts
> 6. Ideally, should be solderable

Wow.  Let me know if you find anything!  I would assume that no such  
thing exists, or it would be in common use.  After all, things like  
(industrial) inkjet printing or powder coating are a lot easier than  
the sort of chemical etching process used to make PCBs for modern  
electronics!  (Although, even with magic ink, you'll STILL have plated- 
through hole issues, and track size issues...)

> There are four broad possibilities I've found:
> 1. Conductive particle suspensions, such as conductive epoxies.
> 2. Conductive thick films
> 3. Conductive ceramics
> 4. Conductive polymers such as polyacetylene

I think Conductive thick films tend to require high-temperature firing  
after they've been deposited.  That's why they go on ceramic substrates.

If by "conductive ceramics", you mean things like "MetalClay"; that's  
even worse.  These are fine nobel metal particles in a polymer base  
(not unlike your conductive epoxies), so they're very expensive AND  
they require a high-temperature firing to remove the base, AND they  
shrink 30%+.

You'd probably be better off looking for an etchant-resitant ink/ 
plastic that you can lay down on conventional copper clad; to be  
processed in the usual way afterward.

BillW

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist