Preparation And Properties Of Phosphate Based Inorganic Thermal Conductive Adhesive

With the development of miniaturization,high integration and multi-function of electronic devices,the heat flux per unit area increases rapidly,which makes the heat dissipation problem become the bottleneck of the development of electronic industry.However,the current thermal management system has a long way to go from highly integrated,so the connection and heat conduction between the components are extremely dependent on the thermal insulation adhesive with high heat conduction,strong adhesion and excellent insulation performance.At present,the research of thermal conductive insulating adhesive generally uses organic materials as matrix and inorganic materials such as alumina,aluminum nitride and boron nitride as reinforcement.Due to the problems of poor intrinsic thermal conductivity and organic/inorganic interface incompatibility of materials,it is difficult to improve the overall thermal conductivity and give consideration to the thermal conductivity,bonding and insulation properties.In this paper,an innovative inorganic thermal conductive insulating adhesive system based on phosphate and diamond was proposed.The modified phosphate inorganic adhesive was used as the matrix,and hydroxylated modified diamond was added to obtain ultra-high thermal conductive insulating adhesive.The basic characterization and thermal,mechanical and electrical properties of the adhesive were tested.The results show that the diamond reinforced ultra-high thermal conductivity insulating adhesive has been successfully prepared.The thermal conductivity is 15.8 w/(m·K),which is 4 times of that reported in the literature.The adhesive material has a wide range,the highest adhesive strength is 6 MPa,the volume resistivity is above 1013,and the insulation property is good.Therefore,the interface shackles between the filled thermal conductive reinforced organic adhesive and inorganic filler are broken,and the feasibility of inorganic materials used in thermal conductive insulating adhesive matrix is fully verified,which provides a new idea for the effective application of diamond in the field of thermal conductivity and has practical application significance.The heat transfer mechanism is explained by computer simulation of phonon spectrum,phonon density of States and interface thermal resistance of phosphate and diamond.The simulation results show that phosphate and diamond belong to inorganic materials,the interface phonon matching degree is high and concentrated in the lowfrequency region,which has a higher contribution to the thermal conductivity;The hydroxyl groups grafted on the diamond surface form hydrogen bonds with phosphate to build a thermal conduction path and reduce the thermal resistance of the interface,thus showing a very high thermal conductivity on the macro level.It has a scientific guiding significance for the further improvement of the thermal conductivity of thermal insulation adhesive,and also makes a supplement for the thermal performance theory of thermal interface composites.Furthermore,epoxy resin was added into the thermal conductive inorganic adhesive to optimize the preparation process,and the organic/inorganic hybrid high-strength thermal conductive insulating adhesive was obtained.The basic characterization and performance test were used to optimize the formulation.The bonding mechanism was explored by testing and analyzing the bonding interface elements,chemical bond types and content.The results showed that the organic/inorganic hybrid high strength thermal conductive insulating adhesive was successfully prepared,the thermal conductivity was3.1 w/(m·K),which met the general thermal conductivity requirements,the electrical insulation performance was good,and the bonding strength was more than 10 MPa.The analysis shows that by introducing new active groups and adding old active groups,more chemical bonds or hydrogen bonds can be formed with more kinds of adhesive matrix,which makes the adhesive failure form close to the cohesive failure which can make full use of the mechanical properties of colloid,so as to achieve the purpose of strengthening the adhesive strength,which has an important reference value for the further study of the adhesive properties of thermal insulation adhesive.