Patent ID: 8431829

Claim:
A printed wiring board comprising: a first substrate having a plurality of conductors including a conductor layer formed on a surface of the first substrate; a second substrate having a plurality of conductors including a conductor layer formed on a surface of the second substrate; an insulation layer comprising an insulative material and formed over the first substrate and the second substrate such that the insulation layer covers the conductor layers formed on the surfaces of the first and second substrates; and a wiring layer formed on the insulation layer and having a plurality of interlayer connection portions formed through the insulation layer such that the conductor layers formed on the surfaces of the first and second substrates are directly and electrically connected through the wiring layer, wherein the conductors of the second substrate have an existing density which is set higher than an existing density of the conductors of the first substrate, the first substrate has an accommodation section configured to accommodate the second substrate, the insulation layer is formed over the first substrate and the second substrate such that the second substrate is embedded in the accommodation section of the first substrate, the insulation layer has a plurality of vias formed through the insulation layer, and the interlayer connection portions of the wiring layer are formed in the vias, respectively.