Electrically conductive adhesives (ECAs) have been explored as a tin/lead (Sn/Pb) solder alternative for attaching encapsulated surface mount components on rigid and flexible printed circuits. However, limited practical use of conductive adhesives in surface mount applications is found because of the limitations and concerns of current commercial ECAs. One critical limitation is the significant increase of joint resistance with Sn/Pb finished components under 85ยฐC/85% relative humidity (RH) aging. Conductive adhesives with stable joint resistance are especially desirable. In this study, a novel conductive adhesive system that is based on epoxy resins has been developed. Conductive adhesives from this system show very stable joint resistance with Sn/Pb-finished components during 85ยฐC/85% RH aging. One ECA selected from this system has been tested here and compared with two popular commercial surface mount conductive adhesives. ECA properties studied included cure profile, glass transition temperature (T g ), bulk resistivity, moisture absorption, die shear adhesion strength, and shift of joint resistance with Sn/Pb metallization under 85ยฐC/85% RH aging. It was found that, compared to the commercial conductive adhesives, our inhouse conductive adhesive had higher T g , comparable bulk resistivity, lower moisture absorption, comparable adhesion strength, and most importantly, much more stable joint resistance. Therefore, this conductive adhesive system should have better performance for surface mount applications than current commercial surface mount conductive adhesives.