Ibiden Company Limited

Toshio Nishiwaki

Tetsuo Amano

A printed wiring board includes a core insulation layer including a resin and having a via conductor through the core insulation layer, a first conductive layer formed on the core layer and including a copper foil and a plated film, an interlayer insulation layer formed on the first layer and including a resin, the interlayer layer having a via conductor through the interlayer layer, and a second conductive layer formed on the interlayer layer and including a copper foil and a plated film. The first layer includes a conductive circuit, the core and interlayer layers have dielectric constants of 4.0 or lower for signal transmission at frequency of 1 GHz and thermal expansion coefficient of 85 ppm/&#xb0; C. or lower at or below Tg, and the foil of the first layer has thickness greater than thickness of the foil of the second layer.

Printed wiring board

A printed wiring board includes a core insulation layer having via conductors through the core layer, a first structure including an interlayer insulation layer on first surface of the core layer and having via conductors through the interlayer layer in the first structure, and a second structure including an interlayer insulation layer on second surface of the core layer and having via conductors through the interlayer layer in the second structure. The interlayer layers have dielectric constants set to be 4.0 or lower for signal transmission at frequency of 1 GHz, the core layer has thermal expansion coefficient at or below Tg set lower than thermal expansion coefficients of the interlayer layers at or below Tg, the coefficient of the core layer at or below Tg is set to be 75 ppm/&#xb0; C. or lower, and the conductors in the interlayer layers are stacked on the conductors in the core layer.

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Ogaki, Japan

Toshio Nishiwaki