| 摘要 |
PURPOSE: A printed wiring board is provided to equally dispose through holes for basic holes dispersed in a specific area, thereby preventing generation of thermal stress distortion in an in-plane direction of a core layer. CONSTITUTION: A core layer having conductivity is prepared. A through hole(17) for back hole is formed on the core layer, and passes through the core layer from a surface to a back surface. A filler(21) for the basic hole is filled within a large diameter via. The through hole(24) is formed in the filler for the basic hole, and passes through the filler for the basic hole along a central axis of the through hole for the basic hole. A conductive small diameter via(25) is formed in a cylindrical shape along an inner wall surface of the through hole.
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