Cu–Sn合金メソ粒子の形成メカニズムとその接合特性

抄録

We have investigated the formation mechanism of Cu–Sn alloy mesoparticles when tin(II) ethylhexanoate was used as a reducing agent. The addition of tin(II) ethylhexanoate led to the color change of the reaction solution. And the size of the mesoparticles and the primary nanoparticles that compose them were affected by the amount of tin(II) ethylhexanoate. Therefore, tin(II) ethylhexanoate plays an important role in the reduction process of Cu oleate. Furthermore, the reduction of Sn²⁺ ion occurs through the underpotential deposition mechanism. Then, Cu–Sn alloy mesoparticle ink was prepared and used as a bonding material for Cu–Cu joint. The maximum shear stress (τ_max) on the bonding interface reached 37 MPa under the bonding temperature of 350°C and the bonding pressure of 30 MPa in an air atmosphere. The higher the bonding temperature, the larger the τ_max tended to be, but there was no dependence on bonding pressure. Although our Cu–Sn alloy mesoparticles are in the meso–size range, they achieved mechanical strength comparable to Cu nanoparticles in a simple bonding process.