Multilayered circuit board

Patent Granted PROBLEM TO BE SOLVED: To enable to efficiently radiate heat generated in a semiconductor element through an insulated base material by joining the semiconductor element to a recess so as to be closely bonded, in an operation temperature region of a semiconductor element circuit board; and to provide a circuit board with a built-in semiconductor element which can securely electrically connect an electronic component such as a semiconductor element with a short wiring and also enables high-density mounting of semiconductor elements, miniaturization and increase in operation speed.