Isotropic conductive adhesive filled with metal-coated polymer spheres — Effects of metal coating on rheological and mechanical properties

An isotropic conductive adhesive (ICA) filled with metal-coated polymer spheres has been studied as a novel approach to increase the mechanical flexibility, and hence the reliability, compared to conventional metal-filled ICAs. In the present paper, effects of the metal coating on the viscosity and the die shear strength were investigated, by comparing ICA materials with metal-coated and uncoated polymer spheres. The sphere diameter is 30 μm, and the metal coating used on the spheres is silver (Ag). The results showed a minor effect of the Ag coating on the die shear strength of the ICA. On the other hand, the Ag coating had an evident effect on the viscosity of the ICA, particularly at low shear rates.