| 摘要 |
PROBLEM TO BE SOLVED: To increase a bonding strength with a substrate in a semiconductor IC, which indispensably requires bending processing of a lead frame for mounting onto the substrate. SOLUTION: A method is provided for mounting the semiconductor IC on a circuit board through a tin coating after the tin coating is formed in the lead frame of the semiconductor IC by plating and performing the bending process of the lead frame. In the method, annealing is not performed to the lead frame. Instead of the tin coating, a tin alloy coating with growth inhibition metals consisting of Sn, Bi, Ag, and In is formed in the lead frame. As the annealing is eliminated, forming a Cu<SB>3</SB>Sn layer can be avoided and generation of cracks during a bending process can be prevented. In addition, generation of void caused by diffusion of copper to the plating film does not occur, even though the plating film is left alone at room temperature, without annealing, because of the effect of the predetermined added metals. For the above reasons, the bonding strength is kept at a high level. COPYRIGHT: (C)2011,JPO&INPIT |
