| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed wiring board having proper hole-filling properties and high reliability. SOLUTION: A plurality of through-holes 3, 4, etc., of different diameters are formed on a board 2. A through-hole plating 5 is applied to the large- diameter through-holes 3 and the small-diameter through-holes 4 to make conductive the front side and the backside of the board 2. Filling materials 6 and 7 contain at least a thermoplastic resin component, such as epoxy resin and a filler component, such as silica fillers. The filler in the filling material 6, filled in the large-diameter through-holes 3 has a lower grain size standard deviation than that of the filler in the filling material 7, filled in the small- diameter through-holes 4.
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