The Research Of Preparation Of Thermal Conductive And Insulating Composite With Precoated Sand Method

For most of the material, those with good thermal conductivity, their electric insulation performance was poor, such as metal. Those with good electric insulation performance, their thermal conductive performance was poor, such as polymer in the nature. However, with the improvement of assembly density of integrated circuit, more and more heat generated when electronic equipment was running. We desperately needed functional materials of thermal conductive and electric insulation. The current solution was polymer-modifying, that is, ceramic particles with high thermal conductivity were added in the resin matrix. Due to the reunion of ceramic particles in the process of preparation, the content of ceramic particles was limited, Most of the content was about 50 vt% ~ 60 vt% or lower, which lead to the improvement of thermal conductivity lower. So we put forward a new preparation process of high thermal conductive and insulation material with precoated sand method. The content of heat conductivity matter reached to about 90 vt%.The Chromite sand/ phenolic resin and silicon carbide / phenolic resin insulating thermal conductive composites were prepared with chromite sand and silicon carbide as the main raw material, phenolic resin as binder, methenamine as curing agent, calcium stearate as additives. The effect of the molding pressure, curing temperature, resin content, chromite sand particle size and particle type on the performance of insulating thermal conductive composites was studied. We concluded that:1?The relative density and thermal conductivity of thermal conductive and insulating composite increased first, then stable with the increasing of molding pressure. When the molding pressure was 59.4 MPa, the relative density and thermal conductivity of composite were 78% and 1.23 W/(m.K), respectively.2?The thermal conductivity of composite increased at initial and then decreased, with the increasing of the curing temperature. When the curing temperature was 220?, the thermal conductivity of composite was 1.23 W/(m.K).3?On the condition of Chromite sand granularity was 70~140 mesh, molding pressure was 59.4 MPa, curing temperature was 220?, the thermal conductivity of composite increased at initial and then decreased, with the increasing of the phenolic resin contents. When the phenolic resin content was 5.0 wt%, the thermal conductivity of composite was 1.66 W/(m·K).4?The volume resistivity and flexure strength of composite increased, coefficient of thermal expansion showed little change, with the increasing of the phenolic resin contents. When the phenolic resin content was 7.0 wt%, the volume resistivity was 19.11×1010??m, flexure strength and coefficient of thermal expansion were 38 MPa and 8.45×10-6 /K.5?The thermal conductivity and relative desity of insulating thermal conductive composite which was prepared by 33?m Chromite sand was higher than which was prepared by 15 ?m Chromite sand. When the phenolic resin content was 8.0 wt%, The thermal conductivity and relative desity of composite which was prepared by 15?m Chromite sand reached to maximum, 1.4 W/(m?K) and 83 %, respectively. The thermal conductivity and relative desity of composite which was prepared by 33?m Chromite sand reached to maximum, 1.6 W/(m?K) and 87 %, respectively.6?On the condition of Chromite sand granularity was 70~140 mesh, molding pressure was 59.4 MPa, curing temperature was 220?, The flexure strength of insulating thermal conductive composite increased at initial and then decreased. When the phenolic resin content was 8.0 wt%, the flexure strength of composite was 1.66 W/(m·K).7?On the condition of molding pressure was 59.4 MPa, curing temperature was 220?,Chromite sand and silicon carbide granularity was 70~140 mesh, The thermal conductivity of Si C/PF composite was higher than Chromite sand/PF composite. And when the phenolic resin content were 6.0 wt% and 5.0 wt%, The thermal conductivity reached to maximum, 3.3 W/(m.K)and 1.66 W/(m.K), respectively.