Thermal Stress And Thermal Properties Of Rubber/filler Modified Epoxy Resin Systems

The epoxy resin has a high bonding strength,a low shrinkage,a good stability and a high adhesion strength,and it is currently one of the most important matrix resins.However,during its curing and thermal cycling process,it has poor toughness and high thermal stress and is prone to cracking.Therefore,its application as a flexible adhesive is limited,especially in large-scale applications of bonding semiconductors such as electronic packaging and chips.In order to solve above problems,the epoxy resin is modified with low Tg thermoplastic toughened rubber,macromolecular toughening resin,small molecular toughening resin and different kinds of fillers.Firstly,the macromolecular toughening resin and small molecule toughening resin is added to study the toughening and heat resistance of the epoxy resin body,and the low Tg thermoplastic toughened rubber is added on the basis of its toughening,and the residual stress generated during the curing and thermal cycling is studied in detail,and finally the influences of different types of fillers on the toughened epoxy systems are explored.In addition,we also envisage extending the comprehensive residual stress assessment method described in this study to modify the epoxy coatings prepared with toughening agents(such as rubber and thermoplastics)in the near future.In the experiment,the Fourier transform infrared spectroscopy is used to characterize the structure before and after the toughening;the mechanical properties are analyzed by a shear test;the differential scanning calorimetry,rotational rheology,dynamic thermodynamic analysis,thermodynamic analysis and thermogravimetric analysis are adopted to evaluate the curing process and thermal performance of the modified epoxy resin system.In addition,the changes in residual stress of the modified epoxy resin system during the process of curing and thermal cycling stress are analyzed with a thin film stress analyzer,and compared with the theoretical calculation data.The results show that after adding the macromolecular and small molecule toughening resin,the toughness and heat resistance of the modified epoxy resin system have been significantly improved;then after adding low Tg thermoplastic toughened rubber on the basis of its toughening,the dynamic thermodynamic analysis and thermodynamic analysis show that the glass transition temperature,linear expansion coefficient and storage modulus of the modified epoxy system have significantly reduced,and the curing residual stress and thermal cycle residual stress are basically as same as the theoretical calculations,which also decrease in a certain degree;the linear expansion coefficient and thermal cycle residual stress value after adding fillers are significantly reduced.Therefore,by modifying the epoxy resin,its toughness can be improved,and the residual stress generated during the process of curing and thermal cycling can be reduced as well.