Preparation and characterization of Ag conductive adhesive with low resistivity

We used bisphenol-F epoxy resin as an insulating polymer matrix, micron silver flakes and silver nanoparticles as conductive fillers, and dimethylformamide (DMF) as an organic solvent to obtain a Ag conductive adhesive with low resistivity. The silver content, organic solvent, and the ratio of micron silver to nano-silver were thoroughly investigated and optimized. Ultimately, it was determined that the optimal formulation for the conductive adhesive consisted of 86 wt % silver with 40:1 micron silver to nano-silver, 10.24 wt % epoxy resin, and 3.76 wt % DMF. Tests for resistivity and shear strength were conducted on the optimal formulation. A resistivity as low as 8 mu Omega cm was obtained. The shear strength can reach to similar to 87 MPa. The reduction in resistivity of the conductive adhesive is attributed to the ability of the formulation to allow micron and nano-silver to be tightly linked in the conductive adhesive to form a good conductive network and promote electron tunneling effect. The current silver conductive adhesive shows promise in microelectronic packaging industries.