| 摘要 |
PROBLEM TO BE SOLVED: To prevent cracks, chipping and peeling from being generated in an insulating layer, and also to improve transmission characteristics in a high-frequency signal transmitted through a line conductor when cutting the end section of a wiring board by a slicing device or the like for forming a step section. SOLUTION: The step section 4 is formed. In the step section 4, the end section of an insulating board 1 is cut out with an interlayer ground conductor layer 1b that is positioned at the lower portion of the end section while an insulating layer 1c of at least the lowermost layer is left. The particle of a sintering body of 13 to 17 wt.% is contained in the internal layer ground conductor layer 1b. The sintering body is made of substantially the same material as the insulating board 1.
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