Abstract: An intermediate substrate is provided which reduces the effect of the difference in the coefficients of linear expansion between the terminals of the substrate and those of a semiconductor integrated circuit device, and which thus lowers the likelihood of disconnection due to thermal stress. The intermediate substrate, which is a planar member made of a polymeric material, includes a substrate core including a main core body having formed therein a sub-core compartment, and a ceramic sub-core section accommodated in the compartment. A first terminal array on the first principal surface side includes two types of terminals, functioning either as power source terminals or ground terminals, and a signal terminal. The array occupies an area entirely included within an orthogonally projected region of the sub-core section projected onto a reference plane parallel to the planar surface of the substrate core.

Abstract: An intermediate substrate is provided which reduces the effect of the difference in the coefficients of linear expansion between the terminals of the substrate and those of a semiconductor integrated circuit device, and which thus lowers the likelihood of disconnection due to thermal stress. The intermediate substrate, which is a planar member made of a polymeric material, includes a substrate core including a main core body having formed therein a sub-core compartment, and a ceramic sub-core section accommodated in the compartment. A first terminal array on the first principal surface side includes two types of terminals, functioning either as power source terminals or ground terminals, and a signal terminal. The array occupies an area entirely included within an orthogonally projected region of the sub-core section projected onto a reference plane parallel to the planar surface of the substrate core.