| 摘要 |
The present invention is directed to improving the reliability of a chip size package mounted on a print board. A metal post 9 is formed in such way that the top surface thereof is larger than the bottom surface, and that the metal post 9 is thinner in the middle than at its both ends. A solder ball 12 is mounted on the top surface of the metal post 9, achieving a larger contact area S' between the metal post 9 and the solder ball 12 than that of the conventional art, which leads to the increased endurance against shear stresses. Furthermore, when the metal post 9 is made thinner in the middle than at its both ends, the metal post 9 is flexible in the lateral direction, and thus capable of further dissipating the stresses accumulated in the boundary area. |
