| 摘要 |
PROBLEM TO BE SOLVED: To provide a relay board capable of absorbing more effectively the shearing stress exerted on solder bumps and printed circuit board using the relay board for multi-step bumps. SOLUTION: Multi-step solder bumps 13 are piled up between a printed board 11 and mounted components 12, and adjacent solder bumps 13a, 13b are mutually connected through a relay board 15 which is made of a porous material. When a thermal expansion difference occurs between the printed board 11 and mounted component 12, a comparatively small displacing force is exerted on the solder bump 13a at the mounted component 12 side, a comparatively great displacing force is exerted on the solder bump 13b at the printed board 11 side, and a shearing strain due to the displacing forces is absorbed by the deformation of a porous material, resulting in the relax of the shearing stress exerted on the solder bumps 13a bonded to the front side and on the solder bumps 13b bonded to the back side. |
