Ibiden Company Limited

Naoki Katsuda

Naoto Ishida

Kota Noda

Nobuhisa Kuroda

A printed wiring board includes a core substrate including a resin insulating layer and multiple conductor layers, a first wiring structure formed on a first surface of the core substrate and including a conductor layer and a resin insulating layer, and a second wiring structure formed on a second surface of the core substrate and including a conductor layer and a resin insulating layer. The core substrate is interposed between the first wiring structure and the second wiring structure such that the resin insulating layers and conductor layers in the core substrate, first wiring structure and second wiring structure are alternately laminated, the resin insulating layer in the first wiring structure has a vol % of resin which is larger than a vol % of resin in the resin insulating layer in the second wiring structure such that a difference in the vol % of resin in the first and second wiring structures is in the range of from 0.5% to 5.0%.

Printed wiring board

A multilayer printed wiring board for mounting a semiconductor element includes a core substrate, a first laminated structure on first surface of the substrate and including a conductive circuit layer on the first surface of the substrate, a resin insulating layer and the outermost conductive circuit layer, and a second laminated structure on second surface of the substrate and including a conductive circuit layer on the second surface of the substrate, a resin insulating layer and the outermost conductive circuit layer. The outermost conductive layer in the first structure has solder pads positioned to mount a semiconductor element and solder bumps formed on the pads, respectively, the outermost conductive layer in the second structure has solder pads positioned to mount a wiring board, and the outermost conductive layers in the first and second structures have thicknesses formed greater than thicknesses of the conductive layers on the surfaces of the substrate.

Growing community of inventors

Ogaki, Japan

Naoki Katsuda