Synthesis and properties of copper conductive adhesives modified by SiO2 nanoparticles

 Copper conductive adhesives were prepared and characterized with epoxy resin as the matrix, a mixture of m-phenylenediamine and diaminodiphenylm ethane as the hardener, and copper particles as the conducting filler. The influence of curing temperature, curing time, additive mass of curing agent, silane coupling agent (SCA), conductive solder and SiO2 nanoparticles on the properties of heat-curable conductive adhesive, such as curing, interconnect, adhesion strength, and electronic conductivity are researched. Results showed that copper powder was dispersed by SCA, preventing the agglomeration and improving the dispersion in matrix adhesive. It is indicated that SiO2 nanoparticles can disperse in the molecular chain of epoxy, which absorbs stress and energy, preventing the spreading of crack. The adhesion strength reached 20 MPa and the bulk resistivity is lower than 1.34×10−3 Ω cm when the adhesives cured at 80 and 145 °C for 2 h, respectively. The adhesion strength could increase to 25 MPa when the SiO2 nanoparticles were doped.