Can you use an FPGA? The signals would need to be digital.

I played with conductive ink once and the layer was thin and hard to connect with. Soldering was difficult. 

How about dispensing conductive epoxy?

I would be curious as to the number of optional connection points required, number of configuration, where/when the configuration is implemented.

Bob K.

-----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

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