A multi-layer substrate connecting to an external electric device includes: a plurality of resin films; and a plurality of conductive patterns. The resin films are stacked together with the conductive patterns. The conductive pattern includes an inner conductive pattern and a surface conductive pattern. The inner conductive pattern is disposed inside of the multi-layer substrate for providing an inner circuit. The surface conductive pattern is exposed on the multi-layer substrate for connecting to the external electric device. The surface conductive pattern has a thickness in a stacking direction, which is thicker than a thickness of the inner conductive pattern.