Northrop Grumman Systems Corporation

Robin E Hamilton

Paul G Kennedy

Thomas J Fagan, Jr

John A Ostop

Gregory Alan Arlow

Raymond A Smith

Martin L Baker

John C Golombeck

Alfred W Morse

Christopher R Vale

Paul M Esker

William S Woodward

Cooling of densely packaged semiconductor devices is achieved by microchannels which extract heat by forced convection and the use of fluid coolant located as close as possible to the heat source. The microchannels maximize heat sink surface area and provides improved heat transfer coefficients, thereby allowing a higher power density of semiconductor devices without increasing junction temperature or decreasing reliability. In its preferred embodiment, a plurality of microchannels are formed directly in the substrate portion of a silicon or silicon carbide chip or die mounted on a ground plane element of a circuit board and where a liquid coolant is fed to and from the microchannels through the ground plane. The microchannels comprise a plurality of closed-ended slots or grooves of generally rectangular cross section. Fabrication methods include deposition and etching, lift-off processing, micromachining and laser cutting techniques.

Method of extracting heat from a semiconductor body and forming

A closed loop liquid cooling system for an RF transistor module including a plurality of elongated microchannels connected between a pair of coolant manifolds for conducting liquid coolant beneath one or more transistor dies to dissipate the heat generated thereby, a heat exchanger, a miniature circulating pump located on the module, and passive check valves having tapered passages for controlling the flow of coolant in the loop. The valves are truncated tapered passage microchannel valves having no moving parts and are fabricated so as to be a part of either the circulating pump, the coolant manifolds, or the microchannels.

Closed loop liquid cooling for semiconductor RF amplifier modules

An electrodeless light bulb assembly having a standard light bulb base located at one end of an extruded cylindrical heat sink including a set of elongated fins extending radially outward from an annular inner body portion. An electrodeless light bulb, excitation coil, and transparent cover for the bulb are located at the other end of the heat sink. A solid state electrodeless lamp driver circuit is thermally coupled to the heat sink and is located in a hollow inner space region formed by the inner body portion. The annular inner body portion also includes at least one but preferably a plurality of boiler/condenser heat pipes located around its periphery for thermally coupling the heat from excitation coil and the driver to the fins where heat is transferred to the air via natural convection. The excitation coil can be formed from a length of conventional electrical conductor or it can be formed from a length of heat pipe connected at one end to the driver and at the other end to the heat sink.

Affordable electrodeless lighting

An electrodeless light bulb assembly including a case or housing supporting an electrodeless light bulb as well as a convection type heat exchanger. A solid state RF driver circuit is located inside the housing and connects to an excitation coil wrapped around the light bulb. The excitation coil comprises a metal heat pipe so as to provide an efficient thermal transport mechanism for the heat generated by the coil and the heat radiated thereto from the electrodeless bulb to the heat exchanger in addition to generating an RF excitation field for the electrodeless light bulb.

RF coil/heat pipe for solid state light driver

Microchannel cooling of high power semiconductor devices

A liquid cooling system contained completely on a circuit board assembly. The liquid cooling system uses microchannels etched within the circuit board, those microchannels being filled with electrically conductive fluid that is pumped by a non-mechanical, magnetic pump. The pump can be separate from the device on the circuit board which is to be cooled or it can be integrated with the device that is to be cooled. In the latter circumstance, the same current which flows through the electronic device is the current which generates the Lorentz force that pumps the electrically conductive fluid through the microchannel.

Non-mechanical magnetic pump for liquid cooling

An RF power amplifier module utilizing a plurality of silicon carbide transistor power amplifier circuits, each including a transistor assembly having multiple cells, respectively providing power amplification of an input signal. In a preferred embodiment of the invention, four mutually staggered silicon carbide transistor assemblies, each containing multiple transistor cells, are operated in parallel while being arranged in close proximity on a common substrate. Each silicon carbide amplifier circuit assembly is commonly driven by a fifth silicon carbide amplifier circuit. The outputs of the parallely driven silicon carbide transistor power amplifier circuits are combined so as to provide a single composite RF output signal which may be in the order of 1000 watts or more when operated at a frequency of, for example, 600 MHz.

Silicon carbide RF power module

Aviation fuel is used as the coolant for a microchannel heat sink for airborne electronics. The use of preexisting aviation fuel as a coolant medium eliminates the weight, size and expense of a separate liquid system dedicated solely to electronics cooling. The heat sink is comprised of a body of material having high thermal conductivity and in which are formed a set of parallel closed-ended microchannels on the order of 0.001 in. by 0.004 in. separated by a distance of 0.001 in.

Growing community of inventors

Millersville, MD, United States of America

Robin E Hamilton