Preparation Of Epoxy-based Anisotropic Conductive Adhesive Films And Study Of The Mechanism Of Action

Anisotropic Conductive Film(ACF)is a green interconnection material for the modern electronics packaging industry,promising to replace tin-lead solder in achieving environmentally friendly manufacturing goals.The conductive microspheres are the core component of the ACF,which are randomly distributed within the ACF and used to provide a conductive path in the Z-direction after hot pressing,while the filler content below the percolation threshold limits the conductivity in the X-Y direction,thus exhibiting anisotropic electrical properties;the insulating resin binder is used to provide the mechanical properties of the ACF,such as rigidity,toughness,etc.ACF has many advantages in the printed circuit interconnect assembly process has many advantages,such as mild processing conditions,simple processing operations,and relatively low costs.In this thesis,the formation mechanism of monodisperse polymeric metal coreshell composite microspheres and the preparation process were systematically investigated as a starting point for the preparation of conductive microspheres in ACF.Firstly,monodisperse polystyrene(PS)microspheres were synthesized using a one-step dispersion polymerization method.The PS-Ni metal core-shell composite microspheres were then prepared by chemical plating using PS microspheres as template spheres.The effects of each component of the plating solution,including the concentration of reducing agent,complexing agent,and main salt,the method of chemical plating,and the loading of PS microspheres in the chemical plating solution on the surface microstructure and morphology of the metal core-shell composite microspheres were discussed.The optimum process conditions were obtained as follows: mechanical stirring with the aid of ultrasound,the main salt concentration of 0.2 M,complexing agent concentration of 0.07 M,and reducing agent concentration of 0.23 M.PS-Ag metal core-shell composite microspheres were prepared using a modified chemical plating method.Compared to conventional chemical plating,activation using smaller-sized platinum nanoparticles(Pt)instead of palladium nanoparticles(Pd)was used to initiate the chemical plating,resulting in a more dense and complete Ag shell.In addition,the effects of plating temperature,time,and PS microsphere loading during the chemical silver plating process on the surface microstructure and morphology of the PS-Ag metal complex microspheres were also investigated.The optimum process conditions were obtained as follows: plating temperature of 15 ℃,time of 60 min,and loading quantity of 4 g/L of PS microspheres.An adhesive system for ACF was developed using epoxy resin(EP)as the base resin,environmentally friendly polyamide resin as the curing agent,and terminally carboxylated liquid nitrile rubber(CTBN)as the toughening rubber and various additives.The optimum curing process parameters were predicted based on the curing kinetics.Secondly,anisotropic conductive adhesive films were constructed by physically blending PS-Ag and PS-Ni composite microspheres with the toughened epoxy resin with the aid of an ultrasonic water bath.Due to the presence of a submicron structure composed of metal core-shell composite microspheres with excellent conductivity in the anisotropic conductive array,ACF creatively presented satisfactory anisotropic electrical properties in the homemade specimens.This thesis provides a systematic description of the formation mechanism and preparation process of PS-based metal core-shell composite microspheres,and a deep analysis of the curing process of EP-based adhesive systems,which is of great significance for the construction of ACF materials.