Patent ID: 7733665

Claim:
A multi-layer substrate connecting to an external electric device, the substrate comprising: a plurality of resin films having electric insulation property; a plurality of conductive patterns disposed on the resin films; and a connection member in a through hole, which is disposed in one of the resin films, wherein the resin films are stacked together with the conductive patterns, the conductive patterns include an inner conductive pattern and a surface conductive pattern, the inner conductive pattern is disposed inside of the multi-layer substrate so that the inner conductive pattern provides an inner circuit, the surface conductive pattern is exposed on the multi-layer substrate so that the surface conductive pattern is capable of connecting to the external electric device, the surface conductive pattern has a thickness in a stacking direction perpendicular to the multi-layer substrate, the thickness of the surface conductive pattern is thicker than a thickness of the inner conductive pattern in the stacking direction, the connection member is arranged between the surface conductive pattern and the inner conductive pattern so that the connection member electrically couples the surface conductive pattern and the inner conductive pattern, the connection member is made of sintered conductive paste; the surface conductive pattern is partially embedded in a corresponding resin film, the resin films includes a first resin film and a second resin film, the first resin film is made of thermoplastic resin, the surface conductive pattern is disposed on the second resin film, the inner conductive pattern is disposed on the first resin film, the second resin film includes a first layer and a second layer, the first layer contacts the surface conductive pattern, the first layer is made of thermoplastic resin having a melting point higher than the first resin film, and the second layer is made of the same material as the first resin film.