Modification And Properties Of Epoxy Thermal Conductive Adhesive

With the rapidly development of integrated circuit and microelectronic technology, the power density of electronic equipment as well the heat generated by electronics in unit volume is gradually increased. To maintain the reliability and lifespan of these equipments, the materials with high thermal conductivity are required to dissipate the heat efficiently. In this paper, epoxy thermal conductive adhesive with excellent performance was prepared. Meanwhile, the effects of various factors on the properties of adhesive were systemically analyzed.(1) The aluminum nitride(Al N) is respectively modified by silane coupling agent KH-560, titanate coupling agent and polyvinylpyrrolidone(PVP). The analysis methods such as FT-IR, TG and SEM were applied to characterize modified AlN particles. The results showed that KH-560 modified Al N was better than other modifier treated AlN to improve the thermal conductivity of adhesives. After treatment by KH-560, the coupling agent molecule was successfully chemically grafted onto the surface of AlN particles, which improves the dispersity and wettability of AlN in the epoxy matrix and enhances the interfacial interaction between filler and epoxy matrix.(2) The AlN/EP adhesives filled with different content of AlN(0, 10 wt%, 20 wt%……70 wt%) were synthesized. The experimental results showed that the viscosity and thermal conductivity of adhesive increased with the increase of filler content; the mechanical property increased initially with an increasing AlN concentration, and then decreased as the AlN concentration was further increased; the shear strength changed a little in the whole content range of AlN. The results analyses indicated that silane coupling agent as the molecular bridge can enhance thermal conductivity and thermal stability of AlN/EP adhesives. When the adhesives filled with 70 wt% raw Al N or KH-560 treated AlN, the thermal conductivities of AlN/EP were up to 1.73 W/(m?K) or 2.24 W/(m?K), respectively. The stability test illustrated that silane coupling agent can improve the onset temperature of decomposition of EP from 221 °C to 248 °C, when the AlN content is 50 wt%. Furthermore, the conclusion that large size particles are more favorable than the small size particles for the enhancement of the thermal conductivity adhesive at the given filling content is drawn in the experience.(3) Graphene oxide was prepared by improved Hummers method. The XRD, FT-IR, Raman and SPM were carred out to characterize the prepared graphene oxide. The SPM result showed that graphene oxide possesses better single layer structure. To further improve the thermal conductivity, the epoxy adhesive filled with hybrid filler was prepared, and a thermal conductivity, 2.77 W/(m?K), exceeding the value of adhesive filled with 70 wt% AlN single particles, was obtained when filled with 50 wt% AlN and 6 wt% graphene oxide hybrid filler. In addition, the viscosity of adhesive filled with hybrid filler has no obvious increase compared with that of filled with 70 wt% AlN single particles.