Metal-metal bonding process using copper oxide nanoparticles

This work performs metal-metal bonding using CuO nanoparticles prepared with salt base reaction in aqueous solution. A colloid solution of CuO nanoparticles was prepared by mixing Cu(NO3)(2) aqueous solution and NaOH aqueous solution. Submicrometre sized leaf-like aggregates composed of CuO nanoparticles were produced at a Na/Cu ratio of 1.7 and at 20 degrees C, though Cu-2(OH)(3)NO3 was also obtained. An aging process, which is a process composed of preparation of the particles at 20 degrees C and then aging them at 80 degrees C, provided transformation from Cu-2(OH)(3)NO3 to CuO with no damage of the leaf structure. The shear strength, which was required for separating discs bonded using the particles as a filler at 400 degrees C in H-2 gas, was 32.5 MPa at the maximum for the particles prepared at the Na/Cu ratio of 1.7 with the aging process. These results indicated that the formation of leaf-like aggregates of CuO particles with high purity led to efficient metal-metal bonding.