Circuit board with self-supporting connection between sides

A copper supporting sheet (5) has holes (9) for connecting semiconductor chips (3) to surface mount components (27). A laminate of polyimide (7) has holes (13) corresponding to the supporting layer holes (9) with copper 15 covering those holes (13). In addition to crossing those holes (13), the copper 15 forms conventional circuit patterns. The side having circuit patterns is populated by surface mount techniques with components (27). The opposite side has silicon chips (3) attached to the copper sheet (5) adjacent to holes (9). Wires (17) are ultrasonically bonded to the chips (3) and extended to the inside of the holes (13) in the polyimide layer (7), where they are ultrasonically bonded to copper (15). Crossover connection of the circuit patterns (17a) are achieved using the same technique. The circuit board is densely populated and cost-effective, with good heat dissipation characteristics.