A multi-layered circuit board a built-in component including multiple terminals, at least one signal pad formed on a top surface of the multi-layered circuit board for signal transmission, each of the at least one signal pad corresponding to one of the multiple terminals, and at least one test pad formed on the top surface of the multi-layered circuit board, each of the at least one test pad corresponding to one of the at least one signal pad for testing an electric path extending from the one signal pad through the one terminal to the each of the at least one test pad.