Electrically conductive adhesives are attractive alternatives to solder and die attach materials in electronic assemblies particularly in the lead free era. Compared to metal filled conductive adhesives, multiwall carbon nanotube (MWCNT) filled adhesives are lightweight, corrosion resistant, high strength and resistant to metal migration. Previous studies of MWCNT filled epoxies on bare copper printed circuit boards identified contact resistance as a challenge for surface mount components where pressure was required during curing to lower the average contact resistance. Currently, we are repeating contact resistance, volume resistivity, lap shear and die shear testing of CNT filled epoxy on printed circuit boards with various surface finishes on the copper pads. The surface finishes under investigation are immersion tin, immersion silver and electroless nickel-immersion gold (ENIG).
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