GaN-HEMT Power Module Structure with Single-sided and Double-sided Aluminum-Clad Printed-Circuit Boards for Small Power Loop Inductance and High Cooling Performance

Gallium nitride high electron mobility transistor (GaN-HEMT) is attractive for fast switching capability and small on-resistance, which motivates researchers to adopt GaN-HEMT for high-power applications. High-power application of GaN-HEMT requires small power loop inductance to suppress switching surge under fast switching but also requires a large power module size for sufficient cooling performance by heat spreading, which results in large wire length and increases the power loop inductance. This paper addresses this problem by proposing a module structure with small power loop inductance and high cooling capability. The proposed module structure incorporates double-sided and single-sided aluminum-clad printed-circuit boards (PCBs) that sandwich the switching devices. These PCBs offer double-sided cooling and small power loop inductance owing to the eddy current generation inside the aluminum clad. A 3kw half-bridge prototype module was constructed to test the proposed structure in comparison with the preceding module structure, which incorporates the double-sided FR4 PCB for the power circuit and the single-sided aluminum-clad PCB for heat spreading. The result successfully revealed that the proposed structure exhibited a small power loop inductance of 1.4nH and a small thermal resistance of 0.72℃/W, which indicates the reduction in power loop inductance by 53% and in thermal resistance by 20%.