| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed wiring board which is excellent in electrical connection property and layer insulation property of a via hole. SOLUTION: The printed wiring board consists of a substrate 1 wherein an inner layer conductor circuit 2 for electrical conduction is formed in both upper and lower surfaces and an outer layer conductor circuit 4 which is formed in an upper surface 81 and a lover surface 82 of the substrate 1 with a layer insulation layer 3 interposed. Besides the inner layer conductor circuit 2, a dummy pattern 21 is formed in at least either an upper surface or a lower surface of the substrate 1. Area difference between the inner layer conductor circuit 2 formed in the upper surface 81 and the inner layer conductor circuit 2 formed in the lower surface 82 including the dummy pattern 21 per 1000 cm2 is at most 600 cm2.
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