A highly conductive bimodal isotropic conductive adhesive and its reliability
Paper in proceedings, 2011
In this paper, micro silver flakes and micro spherical particles were incorporated into the matrix resin of isotropic conductive adhesives (ICAs). Their electrical properties were investigated. The total weight ratio of silver fillers was kept at 75 wt% for all samples. When the content of micro spherical particles was 8 wt%, the bulk resistivity of the bimodal ICAs reduced dramatically to as low as 1.26×10-4 Ω.cm and its viscosity was 24,289 cP under 5rpm at 25°. Scanning electronic microscopy (SEM) images of the bimodal ICAs showed silver fillers well distributed in the matrix resin. In addition, the lap shear strength of different metal surfaces, and the bulk resistivity shifts during aging time under85°/85% RH for more than 500 hours were also measured. The results showed that bulk resistivity shifts of bimodal ICAs remained stable after further cured and the bond strength on the copper surface was the greatest among the three metal surfaces tested.