Multilayered circuit board and semiconductor device

A multilayered circuit board having a single-side laminated structure, the multilayered circuit board which does not include a core substrate having via-holes formed therethrough and vias for providing electrical connection through the via-holes, comprising:

• a plurality of pairs of layers, each pair including a conductor circuit layer and an insulator layer,
• wherein a glass transition temperature of each insulator layer is 170° C. or higher, a coefficient of thermal expansion at the glass transition temperature or lower of each insulator layer is 35 ppm or less, and a modulus of elasticity of each insulator layer is 5 GPa or more,
• wherein the insulator layer includes at least a first resin layer, a second resin layer, and a fiber base member provided between the first and second resin layers, and
• wherein when a thickness of the first resin layer is defined as “B1” and a thickness of the second resin layer is defined as “B2”, B1 and B2 satisfy 0<B2/B1≦1.