Preparation Of Nanosilver/Graphene Composites And Their Application In The Epoxy Resin-based Conductive Adhesive

With the development of science and technology nowadays,the electronic components are developing towards the direction of miniaturization,portability and high-integration.Traditional tin/lead?Sn/Pb?solders can no longer satisfy the requirements of electronic packaging.Electrically conductive adhesives?ECAs?as alternative of Sn/Pb solders with the advantages of environmental friendliness,low temperature processing,high resolution and simple processing,have gained much attention.However,ECAs have drawbacks such as high volume resistivity.It is very necessary to prepare novel ECAs with high electrical conductivity.Due to the excellent properties of graphene and nano silver,the preparation of nano silver/graphene composites and their effect on epoxy resin-based ECAs were investigated in this paper.The main research content and results are as follows:?1?The graphite oxide?GO?was prepared by modified Hummers method.Then silver nanoparticles/graphene nanocomposites?AgNPs/GNs?were synthesized by hydrothermal method used AgNO₃ and GO as raw materials and ascorbic acid as reductant.The crystal structure and morphology of samples were characterized by Fourier transform infrared spectra?FTIR?,X-ray diffraction?XRD?,transmission electron microscopy?TEM?and Raman spectra?Raman?.Different amounts of AgNPs/GNs were introduced into ECAs to study the effect of AgNPs/GNs on the electrical property and shear strength of the ECAs.The results show that the electrical conductivity and shear strength of the ECAs could be improved by the composites.When the content of AgNPs/GNs?the mass ratio of AgNO₃ to GO is fixed at 2:1?was 1.2 wt%,the ECAs had the lowest volume resistivity of 8.21×10^-4?·cm and the largest shear strength of 12 MPa.The volume resistivity decreased by 59.8%and the shear strength increased by 41.2%.?2?The silver nanowires/graphene nanocomposites?AgNWs/GNs?were prepared by solvothermal synthetic method with AgNO₃ and GO as raw materials and ethylene glycol?EG?as reductant.The structure and morphology of samples were characterized by FTIR,XRD,scanning electron microscopy?SEM?,TEM,Raman,X-ray photoelectron spectra?XPS?and UV-Vis.Then the electrical,thermal properties and shear strength of ECAs were tested when different amounts of AgNWs/GNs were introduced into ECAs.The results show the AgNWs/GNs have a profound influence on the improvement of the electrical conductivity and shear strength of the ECAs.The ECAs filled with AgNWs/GNs still possessed good thermal stability.When the content of the AgNWs/GNs?the mass ratio of AgNO₃ to GO is fixed at 1:0.15?was 0.9 wt%,the ECAs had the lowest volume resistivity of 4.34×10^-4?·cm and the largest shear strength of 13.2 MPa.The volume resistivity decreased by 78.7%and the shear strength increased by 55.3%.?3?Silver nanowires?AgNWs?modified by cysteamine can be combined with GO to form AgNWs/GO.Then AgNWs/GO was reduced by hydrazine hydrate to prepare AgNWs/GNs hybrid nanomaterials.The crystal structure and morphology of samples were characterized by using FTIR,XRD,SEM,TEM,Raman and XPS.Then the electrical property and shear strength of ECAs were tested when different amounts of Ag NWs/GNs were introduced into ECAs.The results show the nanocomposites have a significant effect on the improvement of the electrical conductivity and shear strength of the ECAs.When the content of the AgNWs/GNs?the mass ratio of AgNWs to GO is fixed at 4:1?was 0.8 wt%,the ECAs had the lowest volume resistivity of 9.31×10^-5?·cm.The volume resistivity decreased by 95.4%.When the content of the AgNWs/GNs?the mass ratio of AgNWs to GO is fixed at6:1?was 0.6 wt%,the ECAs had the largest shear strength of 14.3 MPa.The shear strength increased by 68.2%.