United Defense LP

Craig Joseph

Kelly W Arnold

T James Dorsch

Anthony C Evans

A module is formed in which semiconductor components are soldered to an electrically conductive heat sink. The electrically conductive heat sink is formed so that it will serve as an electrical bus in an electronic device. The chips of the semiconductor component are metallurgically bonded to the surface of the heat sink. The heat sink uses a heat transfer fluid that flows through an interior of the heat sink, the interior containing an internal element. In the preferred embodiment, the internal element is a plurality of silver plated copper balls. The copper balls are brazed to each other and to the walls of the heat sinks in an assembly process. The heat sink housing will typically be made from copper, with one surface made from molybdenum so that the expansion and contraction of the heat sink housing molybdenum surface will be similar to that of the silicon substrate of the chips, thereby avoiding the problem of the chip substrate cracking and breaking due to thermal flexing.

Electrical bus with associated porous metal heat sink and method of manufacturing same

An oil-cooled inverter for an electric traction motor that uses six IGBT switches to generate 3-phase AC electrical current as its output. The switches are mounted on heat sinks that use hot motor oil (hydraulic fluid) as the heat transfer fluid. An interior of each of the heat sinks contains a heat transfer medium. The heat sink housing is made of molybdenum, which has a thermal expansion rate equal to that of silicon. This allows the circuitry of the inverter to be mounted directly on the top surface of the heat sinks, as the expansion and contraction of the heat sink housing will match that of the silicon substrate of the chips. Since both elements, the heat sink housing and the chip substrate, expand and contract at an equal rate during heating and cooling, the problem of the chip substrate cracking and breaking due to thermal flexing is eliminated. The inverter is in most ways electrically equivalent to prior art inverters, but the upper surface formed by the bank of heat sinks is electrically hot, and is used as part of the inverter circuitry. This allows the elimination of the insulating plate on which the inverter circuitry is normally mounted, as the chips of the inverter circuitry are mounted directly on the upper surface of the heat sinks of the inverter.

Inverter for an electric motor

A method of manufacturing a heat sink for an inverter that utilizes a housing with a porous metallic interior formed from a large plurality of metal balls bonded together to provide a plurality of fluid flow paths. The metal balls serve as heat sinks to dissipate the heat in the fluid that flows through the heat sink. The metal balls must therefore be in thermally conductive contact with each other, and the bond area between the balls must be as large as is feasible to provide a sufficient heat path for the heat from the fluid. The heat sink is intended to be sued with an inverter for an electric motor, so the heat sink housing must be formed from molybdenum to accommodate mounting of circuitry. In order to be susceptible to receiving soldered components the molybdenum surface is nickel plated. The porous metal medium for the heat sink is formed from small (approximately {fraction (3/32)}&Prime; diameter) copper balls. Metallurgical bonding between the balls is achieved by silver plating the balls before brazing so that a copper-silver eutectic brazing compound is formed during the brazing process.

Growing community of inventors

Santa Clara, CA, United States of America

Craig Joseph