Effects of low melting point SnBi58 alloy on the properties of isotropic conductive adhesives

Adequate mechanical and electrical properties and long-term reliability are critical in conductive adhesive interconnects. In order to improve the electrical and mechanical properties of isotropic conductive adhesives (ICAs), reduce contact resistance and enhance the aging resistance of ICAs, the effects of low melting point SnBi58 alloy on the properties of ICAs were studied. The low melting point SnBi58 alloy formed metallurgical bonds between conductive fillers, as well as between the ICAs and a Cu substrate and not only improved the electrical conductivity and mechanical properties of ICAs, but also reduced the contact resistance shift of ICAs effectively. It was found that when the mass ratio of SnBi58 alloy in conductive fillers was maintained at 20 wt%, the bulk resistivity of ICAs reached 4.8×10–4 Ω·cm, the shear strength of ICAs was 27.71 MPa, and the contact resistance shift of ICAs was 7% after aging. In addition, better bulk resistivities and higher shear strengths of ICAs were achieved after aging at 85 °C/85%RH.