Hi Ofer-

I like the idea of configuration this way, going to a pad array and 
configuring the interconnects there. I believe conductive inks for that 
application would be a risk, since it is generally not done.

You might find it easy to design a simple 2 layer circuit which you could 
place like a BGA on top of your pad array which did this configuring. Make the 
pads non-symmetrical to reduce the chance of putting it down the wrong way.

Or buy a simple EPROM, or EEPROM and use that to hold the configuration. Very 
small EEPROMs are available.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ofer Cohen
Sent: Friday, July 25, 2014 12:50 PM
To: [log in to unmask]
Subject: [TN] Printable conductive ink

Hello, Technetters,
It is 8 years since I left the listserv and moved to another job and company. 
I'm returning now in quality position for a company that works in the security 
domain. I somewhat lost the touch, but hope to resharpen ASAP. I glad to see 
here the old known names, from whom I learned a lot then, and hope to continue 
to learn.

I have a question regarding printable circuit: our products are ver complex 
and have many IO options. Currently we are usig 0 ohms resistors and resistor 
networks to switch the proper IO to the card's connectors. But the complexith 
of the cards rises, there are more and more options, and the real estate 
needed for the resistors becomes expensive. Due to some restrictions we are 
using resistors size to 0402, not smaller.

There was an idea to route all the signals to a single BGA-like footprint, and 
print the configuration using conductive ink. The ink should be applied before 
the reflow, because otherwise we should prepare 3D stamp rather than some kind 
of flat stencil.

Did any of you expertienced such solution? If yes - can you refer me to 
materials, processes, etc? The product shold be functional in wide temperature 
range - -40 to +120 deg C. It will be protected with conformal coating.

Regards
Ofer Cohen