Ngk Spark Plug Company, Limited

Sumio Ohta

Yukihiro Kimura

Yasuo Doi

Mitsuru Tamaki

A wiring substrate is configured such that a build-up layer is formed only on a front surface (a single side) of a core substrate and such that the distance between a semiconductor device mounted on the front surface thereof and an electronic component mounted on the back surface thereof or incorporated therein behind the back surface is reduced to thereby enhance electrical characteristics of an electrically continuous path therebetween, and whose overall strength is enhanced so as not to be prone to deflection or warpage. The wiring substrate includes a relatively thin first core substratehaving a front surfaceand a back surfacea relatively thick second core substratesuperposed on the back surfaceof the first core substrateand having a through openingformed therein, the first substrateand the through openingdefining a recessand a build-up layer BU formed on the front surfaceof the first core substrateand including wiring layersandand dielectric layersand

Wiring substrate

The wiring board is provided with the first resin insulating layer , the first filled via penetrating it and filled and formed by the plating, and the second conductor layer formed by the plating on them. In them, the second conductor layer comprises the first resin insulating layer , the electroless plating layer formed on the first filled via , and the electrolytic plating layer composed of plating particle of substantially uniform size, formed thereon.

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Aichi, Japan

Sumio Ohta