| 摘要 |
A ground pattern (12) and power supply pattern (13) which are formed on the surface of a printed wiring board (10) are connected to a ground layer (21) and power supply layer (22) formed as the internal layers via bumps (24a, 24b). The ground pattern (12) need not be connected to the ground layer (21) by uniformly plating the inner side surface of a cavity (43), contributing to an increase in yield and a decrease in cost. When a power supply pattern (13) is to be connected to a power supply layer (22) using through holes, the power supply pattern (13) must be spaced apart from signal pins (14) detouring the region where the through holes are to be formed. However, the distance between the power supply pattern and the signal pins can.be reduced by using bumps. The distance between a semiconductor chip (41) and the signal pins (14) can be reduced to improve the electrical characteristics.
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