Patent ID: 7663460

Claim:
A planar transformer comprising: a primary coil board including a primary coil; a secondary coil board including a secondary coil, the secondary coil board facing and being separated from the primary coil board by a gap; a heat sink having a surface and that is electrically insulating, at least at the surface, the heat sink including, integrally, a generally planar body and a spacer portion lying in a plane substantially perpendicular to the body, the spacer portion being located in the gap between the primary coil board and the secondary coil board; and a magnetic core assembly mounted to the primary coil board and the secondary coil board, wherein the primary coil board and the secondary coil board include respective multilayer boards comprising outer conductive coil patterns on opposite outside surfaces and at least one inner layer between the outer coil patterns, and respective extended portions extending the outer conductive coil patterns to respective side surfaces of the primary coil board and the secondary coil board, respectively, the extended portions being exposed at the side surfaces of the primary coil board and the secondary coil board, the extended portions thermally contacting the surface of the heat sink, the side surfaces of the primary coil board and the secondary coil board being substantially perpendicular to the spacer portion of the heat sink, and the spacer portion is in contact with the primary coil board and the secondary coil board.