Patent attributes
A wiring board (20) includes a first wiring portion (10) having a plurality of wiring layers (1) and a plurality of external connecting bumps (5), and a second wiring portion (15) integrated with the first wiring portion in the direction of thickness. The thermal expansion coefficient of the second wiring portion is made smaller than that of the first wiring portion, and equal to that of a semiconductor chip (30) to be mounted on the wiring board. This suppresses the internal stress resulting from the thermal expansion coefficient difference between the semiconductor chip and wiring board, and increases the reliability of a semiconductor device (50) obtained by mounting the semiconductor chip on the wiring board. The sizes of the opposing surfaces of the first and second wiring portions are also made equal. This requires only one second wiring portion to be formed even when improving the performance of the semiconductor device by mounting a plurality of semiconductor chips on the wiring board, thereby improving the performance at a low cost.
