Anisotropic conductive tape

Retroactively posted March 4, 2005

Another interesting item to put in your toolbox.

Sorry for the lousy URL. This is 3M's 9703 electrically-conducting tape. The catch is that it is only conductive along one axis -- through its thickness -- and insulating otherwise. Thus it is perfect for bonding together multiple side-by-side connections simultaneously... just put a piece of tape down on top of your circuit board's pads (~15 mil minimum recommended spacing) and stick a flexible connector right to it.

No doubt some of you have already run across this stuff, but it's news to me, and would have certainly influenced how I approached board-to-board connectors in space-critical devices. This sort of combination of ease of fabrication, semipermanent connection (it's removable), and mechanical stability is really compelling for sensor-daughterboard applications.

They have a line of similar anisotropic films, which provide much smaller pitch but without the adhesive qualities. Evidently these are commonly used for interfacing to LCD panels.