2002 年 43 巻 8 号 p. 2130-2136
The crack generation energy U1 and the crack progress energy U2 of eutectic Sn–37 mass%Pb solder ball and Sn–36 mass%Pb–2 mass%Ag one were surveyed by the shear test. Both balls were bonded at various reflow cooling rates (10–200 K/min). The shear test was carried out under the condition of two kinds of the shear height, Z=0 \\micron and Z=200 \\micron. U1 and U2 were calculated by multiplying the shear strength by the shear distance. Though U2 was independent on the cooling rate, the ball composition and the shear height, U1 changed depending on these parameters. Only U1 of Sn–36 mass%Pb–2 mass%Ag ball bonding cooled at 200 K/min dropped sharply though U1 of both ball bonding was almost the same and increased with the faster cooling rates in case of Z=0 \\micron. U1 of Sn–36 mass%Pb–2 mass%Ag ball bonding was higher than that of the eutectic ball at each cooling rate as a result of the shear test at Z=200 \\micron. The needle shape Ag3Sn intermetallic compound in Sn–36 mass%Pb–2 mass%Ag ball and near the interface contributed mainly to the lower U1 at Z=0 \\micron because Ni3Sn4 reaction layer formed at 200 K/min was thin. The higher U1 at Z=200 \\micron was due to the fine lamellar structure (Sn phase/Pb phase) in Sn–36 mass%Pb–2 mass%Ag ball. The shear property of the same ball depended on the shear height in the present study.
