Electrically conductive adhesives as vias fill in PCBs: the influence of fill shape and contact metallization on vias resistance stability

Isotropic conductive adhesives (ICAs) can be used to realize joints in SMT assembly or inner PCBs interconnections. The ALIVH technology is an example of applying the ICAs for PCB fabrication. Simpler application is the idea of "metallization" of mechanically drilled holes in double-sided PCBs with ICAs. Such possibility was presented in previous papers; the average measured fill resistance for vias of diameter 0.8 mm was below 50 mOmega. One of the critical parameters of adhesives is their resistance stability during temperature humidity tests and the aim of the paper is to present the results of such testing. It was found, that for some fill shape and Ni/Au contact metallization the fill resistance is below 50 mOmega for holes diameter 0.5 mm and fill resistance changes after the temperature/humidity tests do not exceed few percent