Fabrication of Cu Particles with Porous Surface and Enhanced Sinter-Bondability between Cu Finishes by Physically In Situ Formation of Cu Nanoparticles Using Them

Cu particles with porous surface are fabricated and used as the paste fillers for rapid sintering. The particles are manufactured by the formation of Cu₅Zn₈ on the surface of the Cu particles, followed by dezincification. The porous structure formed on the surface of the Cu particles collapses owing to external compression during sinter bonding and the in situ formation of Cu nanodebris, thereby enhancing the sinter-bondability. The sinter bonding was performed under 10 MPa at 300 °C in air. Higher shear strength was measured for the paste containing Cu particles with a porous surface compared to the identical sized spherical Cu particles at all bonding times. In particular, a near-full-density bondline was formed after bonding for 3 min and the shear strength increased to 15.85 MPa. When bonding was maintained for 10 min, an excellent shear strength of 20.17 MPa was obtained.