Research On High Thermal Conductivity Insulating Thermal Interface Materials

As the power density of electronic equipment grows,its heat generation also gradually increases,and heat dissipation of electronic devices becomes more and more important.The installation of a heat dissipation substrate or heat sink is a commonly used heat dissipation method,but the presence of the interface greatly affects its heat dissipation efficiency.The insufficient connection between the heating element and the heat dissipation element leads to a large amount of interface thermal resistance,which greatly reduces the heat dissipation effect of the device.Thermal interface materials can effectively solve the problem of interface heat dissipation.The basic principle is to increase the actual contact area by filling the voids of the solid contact surface,effectively reduce the interface thermal resistance,and enhance the interface heat transfer efficiency.This paper is dedicated to designing and developing new thermal interface materials to effectively reduce the thermal resistance of the interface.The main research contents include:(1)a composite film was prepared by electrostatically assembling a polyethylene film grafted with negative charge and boron nitride nanosheets,at room temperature and pressure.The thermal conductivity,mechanical properties and insulation properties of the polyethylene film were studied.The results show that the thermal conductivity of the composite film is increased by 41.3% compared with the pure polyethylene film,which is mainly due to the close combination of polyethylene and boron nitride nanosheets.The tensile strength of the composite film reaches 1.82 MPa,which is more pure.The polyethylene film increased by 173.58 and the breaking stress reached 20.39 MPa,which also increased by 148.44% compared with pure polyethylene film.In addition,the composite film has more excellent insulating properties,and retains a considerable part of the transparency.(2)Aiming at the common problems of poor thermal conductivity and thermal conductivity of thermal conductive gels currently on the market,formula design and improvement were carried out.Using aluminum powder and zinc oxide with different particle sizes as thermally conductive fillers,and introduce alkoxy silicone oil as modifier,side hydrogen silicone oil as crosslinking agent,and hydrogen terminal silicone oil as chain extender to improve the overall performance of thermally conductive gel.Through the design of three factors and four levels of experiments,the effects of the ratio of silicon-hydrogen to vinyl,the ratio of crosslinking agent to chain extender,and the content of alkoxy silicone oil on the performance of thermally conductive gel were explored.The field emission electron scanning microscope was used to characterize the raw materials,and the thermal conductivity and thermal resistance of the collar collar thermal resistance & thermal conductivity tester were tested.The rheometer was used to test the rheological properties of the thermal conductivity gel It was characterized and a thermogravimetric analyzer was used to evaluate the reliability of the thermally conductive gel.After formula optimization,the thermal conductivity of the developed thermal conductivity gel reached 5.44(W / m K),while the thermal resistance was reduced to 0.072(Kcm2 / W).And its rheological properties have also been improved to a certain extent,the viscosity of the system has been reduced from 482(Pa · s)of pure vinyl silicone oil to 285(Pa · s),and the highest thixotropic index has reached 6.14.In addition,the mechanical strength of the thermally conductive gel obtained by optimizing the formulation has been improved to a certain extent,the tensile strength has reached 692.4KPa,and the highest elongation at break has reached 91.96%.