Development Of High-Performance Isotropic Conductive Adhesive For Electronic Packaging And The Study Of Its Thermal Kinetics

As an important interconnect material for electronic packaging,the conductive adhesive has unique advantages compared with other metallic solders and pastes,and has been widely used.Although the conductive adhesive has been commercialized,its performance still needs to be further improved.In this thesis study,a high-performance isotropic conductive adhesive?ICA?filled with micro-sized silver particles was developed and its curing and thermal decomposition behavior was studied.To reduce the amount of silver used while improving the performances of the ICA in the same time,the spherical silver coated silica conductive particles?SiO₂@Ag?were prepared and their effects on the comprehensive properties of the ICA were studied.The influences of different filler constituents on the electrical properties of ICA were also studied by finite element simulation analysis.The main contents of this study are as follows:?1?The formulation of a high-performance ICA has been systematically designed.First,based on extensive experimental studies,the range of the fundamental compositions were narrowed,and the standard formula was determined by orthogonal experiments and other test results.Then,all components of the ICA were taken into consideration according to the requirements of pratical application,and the addition range of each component was also determined.The three factors that affect the electrical and mechanical properties of the ICA most were selected through the experiments designed by Plackett-Burman method.Finally,the three factors were optimized by the response surface method and the optimal formula could be designed by the regression equation.The equation is proved to be valuable for the design of formulation.?2?A series of thermal analyses were carried out on the ICA its unfilled matrix resin facricated by using the above formula,from which the curing and thermal decomposition behavior of the ICA and the matrix resin ware well described by the established mathematical models of kinetics.Thus the relationships between the physical properties and the curing conditions,as well as the thermal decomposition stability of the ICA were qualitatively and quantitatively studied.It is proved to be valuable for the selection of curing processes and the prediction of the service life of the ICA at a specific temperature.Moreover,the effects of micro-sized silver powder on the thermal behavior of the matrix resin were also analyzed.?3?The influences of filler constituents on the properties of the ICA were studied,in particular for the effects of a self-made spherical conductive particles,Si O₂@Ag,on the properties of the ICA with micro-sized silver flake as the main filler.First,the monodisperse SiO₂ particles with excellent spherical degree were successfully prepared and compact silver shells were synthesized uniformly on the surfaces of Si O₂ by electroless plating.Then,with the same total mass fraction of the fillers,ICAs filled with different ratios of SiO₂@Ag particles and micro-sized silver flakes were prepared.The electrical and mechanical properties were compared and the micromorphology was also analyzed.Finally,based on the experimental studies,the finite element simulation method was used to model the ICAs with different filler constituents,and the influences of different filler constituents on the electrical property of the ICAs were further studied.Results show that a certain quantity of SiO₂@Ag particles substituting for micro-sized silver flakes can not only improve the electrical and mechanical properties of the ICA,but also effectively reduce the cost of the ICA.