The Influence Of BN And AlN Particles On The Performance Of Thermal Conductive Silicone Adhesive

LED, which are environmental-friendly, power saving and long lasting have caused a revolution in illumination in the 21st century. But the prominent problem is that the heat of chip can't dissipate competely, which severely restrict the wide application of LED. To reduce the thermal resistance of LED packaging, this paper investicates a kind of thermal and insulation adhesive, which is based on silicone rubber and filled with the inorganic fillers, which are surface-modified by siliane coupling agent.This study describes the preparation of the adhesives and the curining progress. Prepare the base, cross-linker, inhibitor, catalyst and fillers according to the following form ula, component A: base, inhibitor, filler,component B: cross-linker,catalyst,filler. In the application, mix the component A and B,stired well,and heated to 60~140℃for about 10~120 minutes.In this paper, the siliane coupling agent KH-570, Z-6040, Z-6020 are used to decrese the thermal contact resistance at the filler-matrix interace by minimzing the interfacial flows. The silane modified filers were characterized by thermogravimetic Analysis (TGA), scanning electron microscopy (SEM) and thermal conductivity. The results showed that the Z-6040 is the most appropriate for BN and AlN, and the appropriate amount of Z-6040 is 2.4%.Finally, test and analysis the thermal, electrical and mechanical performances of the adhesives. The variation of thermal conductivity is that it increases with the increasing of the filler loadings in the beginning, decline when the content is bigger than a certain value. It shows that the thermal conductivity of adhesive with larger BN or AlN particles is higher than that of smaller ones at the same loading level, and the adhesive filled with hybrid filler of different particle sizes show higher thermal conductivity compared with the fillers with single particle size. The dielectric strength decresases with the incresing of the filler loading. The bonding strength increase in the beginning, and decline when the filler content is bigger than a certain value.Besides, this paper also investigates the thermal stability, viscosity, tensile strength and elongation at break, and they can all achieve the requirments of practical application. Through a series of theoretical studies and practical operations, this study develops the following two kinds of thermal conductive adhesives: (a) When the filler is BN, thermally conductivity of the adhesive is 1.02W/(m·K), dielectric strength is bigger than 11.02kV/mm, bonding strength is 2.1MPa. (b)When the filler is AlN, thermally conductivity of the adhesive is 1.85W/(m·K), dielectric strength is 11.02kV/mm, and bonding strength is 3.04MPa.