Study On Anisiotropic Conductive Adhsive Based On Modified Expoxy Resin

Electronic packaging technology has become more and mor e essential in electronic device industry.Isotropic conductive adhesives(ICA)and anisotropic conductive adhesives(ACA or ACF if the ACAs are in the format of films)play important roles in electronic packaging technology.For ACA s,currently there are still many problems to be solved,such as: long-term stablility in storage,limited impact resistance of epoxy resins,and poor stability under high temperature or high humidity environments.This dissertation studied the epoxy resins and conductive particles to improve the performance of ACAs.This dissertation will include the following contents:The improvement of the toughness of epoxy resins: The most important bonding matrix of epoxy resin as ACA is relatively brittle with low toughness.Amphiphilic block copolymers can self-assemble into different morphologies in the epoxy matrix with microstructures.These microstructures can absorb energy when the epoxy resin is impacted to result in the increase of toughness of the epoxy resins.By grafting polyethylene glycol(PEO)blocks with different lengths onto carboxyl-terminated nitrile rubber(CTBN),new block copolymers of PEO-b-CTBNs were obtained.It was found that the self-assembly effect of these block copolymers in epoxy resins can only be achieved when the molecular weight of PEO is greater than 500.Block copolymers of PEO-b-PS-bPMMA and PS-b-PEO-b-PS were prepared by using a PEO with a molecular weight of 2000.These block copolymers were used t o improve the toughness of epoxy resins and to achieve good results.(2)Improvement of the synthesis of conductive particles: The conductive particles are critical for the conductive adhesives,since they not only affect the conductive properties,but also affects the adhesiveness.Polymer microspheres with different particle sizes were synthesized by one-step method and seed method.And the surfaces of the polymer microspheres were plated with Ni by electroless plating.ACAs were prepared by using conductive particles with different diameters,and their corresponding conductivities and adhesion properties were tested.Studies have shown that conductive particles that are too large or too small are not suitable for achieving excellent performance of ACAS.The optimized diameters of the conductive particles are about 5 ?m.