Development Of New Epoxy Encapsulant For IGBT Chip

This paper uses three epoxy resins as the matrix and methylhexahydrophthalic anhydride as the curing agent to study the proportion of epoxy resin,the compounding of two different fillers,the amount of inorganic filler and the amount of toughening agent for each encapsulant performance impact.The surface modification of the filler were explored,the formulation and curing process of the encapsulant were optimized,and an epoxy resin encapsulant for IGBT with low viscosity,high thermal conductivity,and heat resistance and good application performance was prepared.The main research content of this paper:（1）The amount of different epoxy resins.Change the ratio of SRTEM-80 and REDG-80.In order to meet the encapsulation process of IGBT chip and the filling of inorganic fillers,the ratio of SRTEM-80 and REDG-80 is 2:3 for epoxy resin matrix.（2）The mixing ratio of inorganic fillers.Comprehensively comparing the effect of the addition of two inorganic fillers on the performance of epoxy resin encapsulants,the experiment was conducted using five compounding methods.The results showed that when the mass ratio of alumina to silicon fine powder is 3:2,the viscosity is relatively small.The thermal conductivity is better,and the electrical performance is the best.（3）The amount of toughening agent.Compare the amount of toughener CTBN（0 parts,1.25parts,2.5 parts,3.75 parts,5 parts）under different conditions,on the performance of epoxy resin encapsulant.The experimental results show that when the amount of CTBN is the largest,the mechanical properties are the best.As the amount of the toughening agent increases,the viscosity also increases slightly,and the thermal conductivity increases first and then decreases.Therefore,when the amount of CTBN is 3.75 parts,the prepared epoxy resin encapsulates,the material performance is optimal.（4）The amount of Unmodified filling.Formulated according to the best formula obtained from the above research results.Under the same conditions,explore the influence of different filling levels on the performance of epoxy resin encapsulant.The experimental results show that as the filler content increases,the thermal conductivity increases and the viscosity increases rapidly.When the filler content reaches 70wt%,the insulation performance,hydrophobic properties,and heat resistance performance all meet the industrial requirements.When the filler content reaches 75wt%,the thermal conductivity reaches 1.33W/m·k,the viscosity is2861mPa·s,the volume resistivity is 4.05*10¹⁵Ω·m,the breakdown field strength is 24.41KV/mm,tgδ0.0068,water absorption rate is less than 0.1%.（5）Types of modifiers.In order to further improve the thermal conductivity of the epoxy resin encapsulant,the amount of inorganic filler needs to be increased.The inorganic fillers are modified with silane coupling agents KH-560 and KH-570 to improve the wettability of the filler and increase the filler content.The experimental results show that the performance of epoxy resin encapsulant cured by KH-570 modified is relatively good.（6）The amount of modifier.The amount of silane coupling agent KH-570 was studied.The amount of silane coupling agent KH-570 was studied.The results showed that excess KH-570caused the viscosity to increase.The thermal conductivity first increased and then decreased with the amount of modifier.The insulation performance met the requirements.The performance of the epoxy resin encapsulant prepared when the amount of KH-570 is 1.5wt%is relatively optimal.（7）The amount of filling after modification.The filler content has a great influence on the thermal conductivity and viscosity of the epoxy resin.Therefore,by exploring the filler content of the modified inorganic filler,the best formula of the IGBT chip packaging material is obtained.The results show that when the weight of inorganic filler is 80wt%by weight,the thermal conductivity of the encapsulant is up to 1.71W/（m·k）,the decomposition temperature reaches307℃,the volume resistivity is 6.31*10¹⁵Ω·m,the breakdown field is stronger 26KV/mm,tgδis 0.0078,bending strength is 76.97MPa,water absorption rate is less than 0.1%,which satisfies the use of IGBT chips.