Patent ID: 8993894
Filing Date: 2015-03-31
Classification: H05K,Y10T

Abstract:
1. A printed wiring board, comprising: a core substrate having a first surface and a second surface on an opposite side of the first surface of the core substrate; a first conductor formed on the first surface of the core substrate; a second conductor formed on the second surface of the core substrate; a first through-hole conductor formed through the core substrate and connecting the first conductor and the second conductor; and a second through-hole conductor formed through the core substrate and connecting the first conductor and the second conductor a plurality of first cover layers formed on end portions of the first through-hole conductor respectively such that the first cover layers are covering openings of the end portions of the first through-hole conductor respectively; and a plurality of second cover layers formed on end portions of the second through-hole conductor respectively such that the second cover layers are covering openings of the end portions of the second through-hole conductor respectively, wherein the second through-hole conductor has a diameter which is greater than a diameter of the first through-hole conductor, the first through-hole conductor has a roughened inner wall forming an interior space, the second through-hole conductor has a roughened inner wall forming an interior space, the roughened inner wall of the first through-hole conductor has an arithmetic average roughness which is set lower than an arithmetic average roughness of the roughened inner wall of the second through-hole conductor, wherein the arithmetic average roughness of the roughened inner wall of the first through-hole conductor is set at 0.1 μm or greater and 0.2 μm or lower and wherein the arithmetic average roughness of the roughened inner wall of the second through-hole conductor is set in a range of more than 0.2 μm to 0.3 μm or lower and the interior space of the first through-hole conductor and the interior space of the second through-hole conductor are filled with a filling material comprising a resin and an inorganic filler.