a system package using flexible optical waveguides and electrical wires , and a signal processing method thereof are disclosed . several rigid substrates having highly integrated electronic elements and optical elements mounted thereon can be electrically and optically connected by using flexible substrates that are electrically wired and optically connected . the package can be variously changed when configuring the package by the flexible substrate and the heat dissipation device and the electromagnetic shielding device are installed in the inside of the package , making it possible to solve electromagnetic wave interference problems and thermal problems occurring in the inside of the package .