Apparatus and methods according to the present invention preferably utilize electroosmotic pumps that are capable of generating high pressure and flow without moving mechanical parts and the associated generation of unacceptable electrical and acoustic noise, as well as the associated reduction in reliability. These electroosmotic pumps are preferably fabricated with materials and structures that improve performance, efficiency, and reduce weight and manufacturing cost relative to presently available micropumps. These electroosmotic pumps also preferably allow for recapture of evolved gases and deposited materials, which may provide for long-term closed-loop operation. Apparatus and methods according to the present invention also allow active regulation of the temperature of the device through electrical control of the flow through the pump and can utilize multiple cooling loops to allow independent regulation of the special and temporal characteristics of the device temperature profiles. Novel microchannel structures are also described.

Electroosmotic microchannel cooling system

A two-phase liquid cooling system has a container structure that has at least one wall with sufficient flexibility that the wall expands as the coolant vapor expands thereby maintaining the internal container pressure substantially the same as the ambient environmental pressure. Coolant boiling overshoot is reduced by allowing residual gases to remain in the cooling system. More particularly, sufficient residual gas is maintained in the system so that some of the gas dissolves in the liquid coolant when the device is not operating and is at ambient temperature. During warm-up, the residual gas comes out of solution and creates nucleation sites that initiate boiling and prevent overshoot. Additional nucleation sites can also be added to reduce overshoot by treating the inside surfaces of the container structure, for example by laser machining, to create nucleation sites.

Two-phase component cooler

A computer chassis assembly that includes a heat pipe which thermally couples an electronic package to multiple fan units. The heat pipe provides a computer chassis that sufficiently cools internal heat generating components without placing the components in close proximity to the fans.

Multiple-fan microprocessor cooling through a finned heat pipe

A method and apparatus is disclosed for cooling a multi-chip module using embedded heat pipes. Semiconductor chips are disposed into the multi-chip module through cavities in the module substrate. The semiconductor chips engage heat pipes embedded within the substrate. The heat pipes conduct heat away from the semiconductor chips through a heat conductive bonding layer.

Cooling multi-chip modules using embedded heat pipes

An improved heat dissipation device particularly suited for removing heat from a surface mounted integrated circuit component coupled to a printed circuit board in a portable computer. Vias, which are at least partially filled with a heat conductive material, improve heat transfer between a component and a heat conductive block mounted on opposite surfaces of the circuit board. A first section near one end of the heat pipe is attached to the heat conductive block in a channel formed receptive to the heat pipe. A second section of the heat pipe including the second end is attached to a metal plate which is affixed beneath the keyboard. Heat from the component flows through the vias to the block and is transferred by the heat pipe to the metal plate where it is dissipated.

Dissipation of heat through keyboard using a heat pipe

A bellows type heat pipe which conducts heat away from an electronic device to a heat sink. The heat pipe is a sealed bellows type container which has an evaporator section at one end and a condenser section at an opposite end. The evaporator section contains a saturated radial wick while the condenser section is lined with a radial wick and a circumferential wick. A corrugated slab wick is longitudinally disposed within the heat pipe interconnecting the evaporator and the condenser sections. The evaporator section is placed on the electronic device and the condenser section is enclosed in a housing which is connected to a heat sink. In operation, the electronic device generates heat energy which causes the fluid in the evaporator to vaporize building a vapor pressure in the heat pipe. The heat pipe expands in the direction of the condenser causing the condenser section to make intimate contact with the inside of the housing. The vapors condense at the condenser section and are brought back to the evaporator section via the circumferential wick, the walls of the bellows vessel and the wick slab.

George P. Peterson

Papers

Bellows heat pipe for thermal control of electronic components