Synthesis of a siloxane oligomer containing methyl acryloxy group for promoting the adhesion of addition-type silicone rubber to copper plate

Abstract

An adhesion promoter containing methyl acryloxy group was synthesized according to a non-hydrolysis sol-gel method with methyl phenyl silicone oil containing hydroxyl terminal group, methyl vinyl dimethoxy silane, and γ–methyl acryloxy propyl methyl dimethoxy silane (KH572) as raw materials and then applied in an addition-type silicone rubber. The structure of the product was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectrum (1H NMR). In addition, scanning electron microscope (SEM), mechanical testing machine and video-based optical contact angle measuring instrument were used to test its performance. We found that the adhesion promoter largely improved the bonding performance of the addition-type silicone rubber and showed the better compatibility with liquid silicone resins. When the amount of the adhesion promoter was 2.0 phr, the shear strength between silicone rubber and copper plate reached 1.33 MPa. The optical performance test results indicated that the light transmittance of silicone rubber was slightly changed when the addition amount of the adhesion promoter was no more than 2.0 phr, and this met the encapsulation requirements of electronic packaging adhesives. The contact angle test results indicated that the adhesion promoter reduced the static contact angle between the liquid silicone rubber and copper plate surface and improved the wettability. In addition, oxidation experiments, thermal resistance experiments, SEM tests and XPS surface analysis preliminarily proved that the adhesion promoter could significantly enhance the adhesion via chemical bonds formed with both the cured silicone rubber and the surface of copper plate substrate.