| abstract |
After a microcrystalline layer having a grain size that is finer than that of a base member is formed on the surface of at least one of a first bonding portion and a second bonding portion, the gap between the first bonding portion and the second bonding portion is filled with a solution into which copper oxide can be eluted, so as to deposit copper oxide contained in the surface oxide film into the solution. By applying pressure and by heating at a temperature of at most the copper recrystallization temperature, the components contained in the solution are removed except for copper, so as to elute copper oxide, thereby bonding the first bonding portion and the second bonding portion via the copper thus deposited. Subsequently, the copper is solid-phase diffused into the first bonding portion and the second bonding portion. |