Study On The Preparation And Properties Of Epoxy Resin Composite Insulating Adhesive With High Thermally Conductive

With the wide application of high current power module and the rapid development of electrical and electronic equipment towards high-speed,high-frequency,high-power density and high integration,more and more components are carried on the printed circuit board?PCB?,and the power consumption per unit volume of components is increasing,so the heat dissipation becomes a bottleneck problem that restricts the reliability and life of electrical and electronic equipment.In order to ensure the lifetime,stability and reliability of electrical and electronic equipment,it is urgent to improve the heat dissipation performance of PCB substrate-copper clad plate?CCL?while ensuring the insulation and mechanical properties.The low thermal conductivity of insulating adhesive layer greatly limits the heat dissipation ability of CCL.Epoxy resin with excellent electrical insulation,heat resistance and mechanical properties is used to prepare composite insulation adhesive for copper clad laminates,but its thermal conductivity is generally only about 0.2W/?m·K?.Micro nano composite modification is an important mean to improve the thermal conductivity of epoxy resin,but a large number of thermal conductive fillers filled with epoxy resin will lead to the degradation of its processability,mechanical properties and electrical insulation properties,which can not meet the application requirements of high thermal conductive CCL.This paper focuses on solving the problem of poor processability,low thermal conductivity and low electrical insulation of epoxy resin composite insulation adhesive under high filling amount by heat conduction filler modification and filler compounding.Based on the formula with excellent performance obtained in this paper,aluminum based copper clad laminate was prepared and its properties were tested.Finally,COMSOL is used to study the influence of thermal conductivity of insulating layer,thermal environment and thickness of insulating layer on the heat dissipation of aluminum-based copper clad laminate.In order to solve the problems of low adhesive force and high adhesive viscosity between insulation adhesive and copper foil,two coupling agents,JFCP1 and JFCP2were used to modify heat conduction filler.It was found the synergistic use of coupling agents JFCP1 and JFCP2 can reduce the viscosity of the composite adhesive better without affecting its thermal conductivity and the adhesive prepared also has high adhesive strength with copper foil.In order to solve the problem of high viscosity of composite adhesive,the filler formula was optimized by theoretical calculation and experimental research.In theoretical,when the ratio of Al₂O₃ fillers is 12:5:1.5??m?=2:3:5,the fitting curve of particle size distribution of composite filler is the closest to Fuller curve,which means formula with particle size ratio 2:3:5 should have the lowest viscosity.But in the actual experiment,it is found that the formula with particle size ratio 5:4:1 has the lowest viscosity.When the proportion of large particle size filler is more than 50%and the particle size matching is reasonable,lower viscosity can be get.When the proportion of medium particle size filler or small particle size filler is too large,viscosity increases significantly.When the filler filling amount is 80wt%,the thermal conductivities of composite adhesives increase by 10 times or more.Formula with particle size ratio 8:1:1 has the highest hermal conductivities-2.5W/?m·K?.Formula with particle size ratio 5:3:2 has lower viscosity but higher filling rate,its thermal conductivity reaches 3W/?m·K?,when filling amount is 90wt%.The adhesive with large particle size and closer packing structure has higher breakdown field strength.Formula with particle size ratio 7:2:1 has the highest breakdown field strength which is 32.37k V/mm.Both the dielectric constant and dielectric loss are not directly related to the filler structure.In this paper,formula with particle size ratio 5:3:2,found to have good comprehensive performance was adopted to make aluminum based copper clad laminates with insulation layer thermal conductivity of 2W/?m·K?and 3W/?m·K?.After testing,the two kinds of CCL can withstand voltage up to 6k V?DC?and 5k V?AC?,CTI>300s and have excellent peel strength of 1.71N/mm and 1.43N/mm respectively.All indexes are higher than the requirements of IPC 4101/126 standard.Finally,with the high power LED chip as the heat source,the influence of the thermal conductive CCL on the temperature rise of the module is studied.The results show that improving the thermal conductivity of the insulating layer of aluminum-based CCL can improve the luminous efficiency and lifetime of LED module.In high-power LED applications,to reduce the temperature rise,the thermal conductivity of the insulation layer and the heat dissipation environment should be improved together.With the decrease of the thickness of the insulating layer of the aluminum based copper-clad laminate,the heat dissipation performance becomes better,but the thickness of the insulating layer has limited influence on the heat dissipation.The key to improve the heat dissipation of the LED module is still to improve the thermal conductivity of the insulating layer.The comprehensive study shows that the 2W/?m·K?and 3W/?m·K?high thermal conductive insulating adhesives prepared in this paper can meet the basic requirements of the application of CCL,and are expected to provide theoretical guidance and experimental reference for the research and development of high thermal conductivity CCL.