| 摘要 |
PURPOSE:To reduce a soldering temperature, and to prevent generation of a crack even in a moistened semiconductor package by employing an Sn-Pb solder added with a predetermined amount of Bi when the moistened package is placed on a board. CONSTITUTION:When a chip 1 is placed on a tab 21 having leads 2 and a package 4 sealed with molding resin 3 is left to stand for in the atmosphere, the resin 3 absorbs moisture in the air, moisture is also immersed from between the leads 2 and the resin 3, and condensed on the surfaces of the tab 2a and the chip 1. If such a package 4 is soldered, the entire package 4 is exposed with soldering temperature, and hence it is necessary to work at a higher temperature than a melting point. Thus, Sn-Pb solder added with Bi in a range less than 13wt.% exceeding 10wt.% is employed. Thus, the soldering temperature is reduced, internal stress generated at the resin due to vapor pressure of the moisture immersed to the package is reduced, and it is connected at lower temperature than that for lowering the bending strength of the resin to prevent a crack of the resin. |
