Showing papers on "Heat sink published in 2007"

State of the Art of High Heat Flux Cooling Technologies

Abstract: The purpose of this literature review is to compare different cooling technologies currently in development in research laboratories that are competing to solve the challenge of cooling the next generation of high heat flux computer chips. Today, most development efforts are focused on three technologies: liquid cooling in copper or silicon micro-geometry heat dissipation elements, impingement of liquid jets directly on the silicon surface of the chip, and two-phase flow boiling in copper heat dissipation elements or plates with numerous microchannels. The principal challenge is to dissipate the high heat fluxes (current objective is 300 W/cm2) while maintaining the chip temperature below the targeted temperature of 85°C, while of second importance is how to predict the heat transfer coefficients and pressure drops of the cooling process. In this study, the state of the art of these three technologies from recent experimental articles (since 2003) is analyzed and a comparison of the respective merits and ...

Led lamp with a heat sink assembly

Abstract: An LED lamp includes a heat absorbing member having a hollow, cylindrical configuration, a lamp base, a plurality of LED modules and a heat sink The heat absorbing member defines a through hole therein The heat sink is secured to a top portion of the heat absorbing member The lamp base is secured to a bottom portion of the heat absorbing member The LED modules are mounted on an outer sidewall of the heat absorbing member, and each of the LED modules includes a printed circuit board and a plurality of LEDs mounted on the printed circuit board Each of the heat pipes has an evaporating portion received in an inner sidewall of the heat absorbing member and a condensing portion connecting with the heat sink The condensing portions of the heat pipes are radially arranged on the heat sink, radiating outwardly from a central point of the heat sink

Evaluation of Jet Impingement, Spray and Microchannel Chip Cooling Options for High Heat Flux Removal

Abstract: Thermal management for high heat flux removal from microelectronic chips is gaining critical importance in many earth-based and space-based systems. Heat fluxes greater than 1 MW/m2 (100 W/cm2) have already been realized in high-end server applications, while cooling needs in next generation chips and advanced systems such as high-power electronics and electrical systems, pulsed power weapons systems, solid-state sensors, and phased-array radars are expected to reach 5–10 MW/m2 (500–1000 W/cm2). After evaluating the contributions from different thermal resistances in the chip-to-ambient thermal path, this paper presents a critical review and research recommendations for three prominent contending technologies: jet impingement, spray cooling, and microchannel heat sinks.

LED lighting system

Abstract: A light emitting diode lighting device and system that can be used for illuminating the interior and/or exterior of vehicles, aircraft, watercraft, signage or buildings is provided. It includes a voltage feedback constant current power supply circuitry and high power LEDs. The printed circuit assemblies are firmly mounted onto a continuous or semi-continuous mounting channel case that also works as a heat sink. By this means, it not only increases the reliability of the LED lighting tube but also it provides sufficient heat dissipation capability for the heat generated by the LEDs. Since the operating temperature of the LEDs is controlled and stays in cool condition, it dramatically increases the LED's lifetime and efficiency. The end caps of this LED lighting device are fully compatible with existing conventional fluorescent light fixtures and can directly replace those fluorescent lighting tubes in vehicles, mass-transit, watercrafts, aircrafts, signage, furniture, equipment or buildings with minimal modifications.

Experimental and Numerical Study of a Stacked Microchannel Heat Sink for Liquid Cooling of Microelectronic Devices

Abstract: One of the promising liquid cooling techniques for microelectronics is attaching a microchannel heat sink to, or directly fabricating microchannels on, the inactive side of the chip. A stacked microchannel heat sink integrates many layers of microchannels and manifold layers into one stack. Compared with single-layered microchannels, stacked microchannels provide larger flow passages, so that for a fixed heat load the required pressure drop is significantly reduced. Better temperature uniformity can be achieved by arranging counterflow in adjacent microchannel layers. The dedicated manifolds help to distribute coolant uniformly to microchannels. In the present work, a stacked microchannel heat sink is fabricated using silicon micromachining techniques. Thermal performance of the stacked microchannel heat sink is characterized through experimental measurements and numerical simulations. Effects of coolant flow direction, flow rate allocation among layers, and nonuniform heating are studied. Wall temperature profiles are measured using an array of nine platinum thin-film resistive temperature detectors deposited simultaneously with thin-film platinum heaters on the backside of the stacked structure. Excellent overall cooling performance (0.09 ° C/W cm 2 ) for the stacked microchannel heat sink has been shown in the experiments. It has also been identified that over the tested flow rate range, counterflow arrangement provides better temperature uniformity, while parallel flow has the best performance in reducing the peak temperature. Conjugate heat transfer effects for stacked microchannels for different flow conditions are investigated through numerical simulations. Based on the results, some general design guidelines for stacked microchannel heat sinks are provided.

Suppression of intermetallic reaction layer formation by controlling heat flow in dissimilar joining of steel and aluminum alloy

Abstract: In order to suppress the formation of intermetallic reaction layer during laser welding of steel and aluminum alloy dissimilar materials, effect of backing block (heat sink) was investigated. FEM analysis as well as welding experiments with various backing blocks for controlling heat flow were performed. It was found that thickness of intermetallic reaction layer was reduced by increasing welding speed and by applying a backing block with higher thermal conductivity. FEM analysis also showed that when increasing welding speed or applying a backing block with higher thermal conductivity, molten time of aluminum alloy became shorter and predicted thickness of intermetallic reaction layer became thinner. It could be concluded that the thickness of intermetallic reaction layer could be suppressed by using a backing block (as a heat sink) for controlling heat flow in welding region. The joining strength was strongly dependent on the thickness of intermetallic reaction layer. Therefore the backing block was significantly effective for controlling heat flow and consequently for attaining good joining strength.

LED lamp with a heat sink

Abstract: An LED lamp includes a heat sink and an LED module. The heat sink includes a body, a plurality of radial partition fins extending evenly from an outer periphery of the body and a curved wall surrounding lower portions of the fins. The fins, the outer periphery of the body and the wall together define a plurality of channels each having a lower opening and a top opening. The LED module includes a plurality of LEDs and is received in the absorbing portion of the body. The LED module is supported by the absorbing portion of the body of the heat sink. Heat generated by the LEDs is transferred to the fins via the body. From the fins, the heat is dissipated to air. The channels each function as a chimney for accelerating heated air to flow upwardly through the fins.

Selective laser melting of heat transfer devices

Abstract: Purpose – To fabricate and characterise novel heat sinks manufactured by selective laser melting (SLM). The investigation explores features of SLM produced heat sinks that may be exploited to improve their heat transfer capability.Design/methodology/approach – The study was conducted on heat sinks manufactured from 316L stainless steel and aluminium 6061. The heat transfer devices' thermal and pressure drop performances were determined by experimental test.Findings – The research demonstrates the performance enhancements that can be realised by using novel heat sink designs, fabricated by SLM, over conventional pin fin arrays. aluminium 6061 is used with the process to illustrate the improvement in heat transfer provided by higher conductivity feedstock materials.Research limitations/implications – Although the manufacturing technique is still in the development stage and the heat transfer devices that have so far been manufactured should not be considered optimal, the potential for creative new designs a...

Towards a Thermal Moore's Law

Abstract: Thermal design power trends and power densities for present and future single-core microprocessors are investigated. These trends are derived based on Moore's law and scaling theory. Both active and stand-by power are discussed and accounted for in the calculations. A brief discussion of various leakage power components and their impact on the power density trends is provided. Two different lower limits of heat dissipation for irreversible logic computers that have previously appeared in the literature are discussed. These are based on the irreversibility of logic to represent one bit of information, and on the distribution of electrons to represent a bit. These limits are found to be two or more orders of magnitude lower than present-day microprocessor thermal design power trends. Further, these thermal demand trends are compared to the projected trends for the desktop product sector from the International Technology Roadmap for Semiconductors (ITRS). To evaluate the thermal impact of projected power densities, heat sink thermal resistances are calculated for a given technology target. Based on the heat sink thermal resistance trends, the evolution of a consistent air-cooling limit is predicted. One viable alternative to air-cooling, i.e., the use of high-efficiency solid-state thermoelectric coolers (TECs), is explored in detail. The impact of different parasitics on the thermoelectric figure of merit (ZT) is quantified.

Survey on High-Temperature Packaging Materials for SiC-Based Power Electronics Modules

Abstract: High temperature SiC devices need the materials for device packages also capable of working at higher temperature than those for Si devices. This paper presents a selection of materials that are potentially suitable for use in high temperature package assembly, including die attach, substrate, interconnections, encapsulation, case, heat spreader and heat sink. The temperature under consideration is up to 250degC, corresponding to the need of many applications, including automobiles and aircraft.

Photovoltaic connection system

Abstract: A photovoltaic connection system for maximum current output and heat dissipation properties. The connection system includes a connection box with improved heat transfer capability to permit higher current output capacity. Diodes are surface-mounted on a printed circuit board inside of the connection box. An optional metal plate may be mounted inside the cover plate of the connection box as a heat sink for dissipating heat from the diodes. The metal in the plate has good thermal transfer characteristics, e.g., copper or aluminum.

Light-emitting diode lamp

Abstract: A light-emitting diode (LED) includes a heat sink ( 10 ) having a cross section along an axial direction thereof being U-shaped. The heat sink includes a substrate ( 102 ) and a sidewall ( 11 ) extending from an outer periphery of the substrate. A circuit board ( 40 ) is received in the heat sink and arranged on the substrate. At least one LED ( 30 ) is arranged on and electrically connected to the circuit board and thermally connected with the substrate of the heat sink. A plurality of fins ( 100 ) extend outwardly from an outer surface ( 110 ) of the sidewall of the heat sink. Each fin has a plurality of branches ( 100 a, 100 b ) being connected together at the outer surface of the sidewall and being spaced from each other at outer-peripheries thereof.

High power LED lighting assembly incorporated with a heat dissipation module with heat pipe

Abstract: A high power light emitting diode (LED) lighting assembly incorporated with heat dissipation module is provided. The LED lighting assembly includes a heat exchange base, at least one LED array, at least one heat pipe and a heat dissipation module. The heat exchange base includes at least one LED configuration plan for mounting of the LED array and at least a hollow part for insertion of the heat pipe. The LED array is arranged at a predetermined projecting angle at the LED configuration plane. The heat pipe includes a heated section, a cooling section and a conducting section, and contains a working fluid therein. The heat exchange base is mounted to the heated section and the heat dissipation module is mounted to the cooling section. The thermal energy generated by the LEDs is conducted from the heat exchange base to the heated section of the heat pipe, whereby allowing the working fluid in the heat pipe to be heated and vaporized, and flows, from the conducting section to the cooling section for dissipation at the heat dissipation module.

Interfacial design of Cu/SiC composites prepared by powder metallurgy for heat sink applications

Abstract: In order to dissipate the heat generated in electronic packages, suitable materials must be developed as heat spreaders or heat sinks. Metal matrix composites (MMCs) offer the possibility to tailor the properties of a metal (Cu) by adding an appropriate reinforcement phase (SiC) to meet the demands for high thermal conductivities in thermal management applications. Copper/SiC composites have been produced by powder metallurgy. Silicon carbide is not stable in copper at the temperature needed for the fabrication of Cu/SiC. The major challenge in development of Cu/SiC is the suppression of this reaction between copper and SiC. Improvements in bonding strength and thermo-physical properties of the composites have been achieved by a vapour deposited molybdenum coating on SiC powders to control the detrimental interfacial reactions.

Heat sink and lighting device comprising a heat sink

Abstract: A heat sink is provided. The heat sink may include an open cavity formed by a cavity wall, a cavity bottom wall thereof including a light source region adapted to have a light source mounted thereon and a lateral cavity wall thereof including a reflection region adapted to reflect light emitted from the light source; a heat spreading and dissipation structure covering at least part of an exterior of the heat sink including a bottom region and a lateral region, the heat spreading and dissipation structure including a plurality of vertically aligned fins; an air guidance structure adapted to separate the heat sink from an air flow generator; and at least one mounting column for attaching the heat sink to a lighting device.

Integral ballast lamp thermal management method and apparatus

Abstract: A lamp having a lighting source, integral electronics, and a thermal distribution mechanism disposed in a housing. The thermal distribution mechanism may include a variety of insulative, radiative, conductive, and convective heat distribution techniques. For example, the lamp may include a thermal shield between the lighting source and the integral electronics. The lamp also may have a forced convection mechanism, such as an air-moving device, disposed adjacent the integral electronics. A heat pipe, a heat sink, or another conductive heat transfer member also may be disposed in thermal communication with one or more of the integral electronics. For example, the integral electronics may be mounted to a thermally conductive board. The housing itself also may be thermally conductive to conductively spread the heat and convect/radiate the heat away from the lamp.

LED lamp cooling apparatus with pulsating heat pipe

Abstract: An LED lamp cooling apparatus ( 10 ) includes a substrate ( 11 ), a plurality of LEDs ( 13 ) electrically connected with the substrate, a heat sink ( 19 ) for dissipation of heat generated by the LEDs and a pulsating heat pipe ( 15 ) thermally connected with the heat sink. The pulsating heat pipe includes a plurality of heat receiving portions ( 154 ) and a plurality of heat radiating portions ( 155 ), and contains a working fluid ( 153 ) therein. The substrate is attached to the heat receiving portions of the pulsating heat pipe and the heat sink is attached to the heat radiating portions of the pulsating heat pipe. The heat generated by the LEDs is transferred from the heat receiving portions to the heat radiating portions of the pulsating heat pipe through pulsation or oscillation of the working fluid in the pulsating heat pipe.

Electronic control apparatus

Abstract: An electronic control apparatus can be reduced in size and cost by eliminating certain component parts such as a power board, etc. The apparatus includes a housing, a heat sink, semiconductor switching elements having terminals and mounted on the heat sink, a circuit board arranged in opposition to the heat sink, conductive plates connecting between the circuit board and the semiconductor switching elements, and a cover receiving the semiconductor switching elements and the circuit board in cooperation with the heat sink. The conductive plates have the press-fit terminal portions press-fitted into the through holes in the circuit board, and the individual conductive plates are arranged along a lead-out direction in which the individual terminals of the semiconductor switching elements lead out, and are bonded to the individual terminals.

Thermal cycler for PCR

Abstract: An instrument for performing highly accurate PCR employing an assembly, a heated cover, and an internal computer, is provided. The assembly is made up of a sample block, a number of Peltier thermal electric devices, and a heat sink, clamped together. A control algorithm manipulates the current supplied to thermoelectric coolers such that the dynamic thermal performance of a block can be controlled so that pre-defined thermal profiles of sample temperature can be executed. The sample temperature is calculated instead of measured using a design specific model and equations. The control software includes calibration diagnostics which permit variation in the performance of thermoelectric coolers from instrument to instrument to be compensated for such that all instruments perform identically. The block/heat sink assembly can be changed to another of the same or different design. The assembly carries the necessary information required to characterize its own performance in an on-board memory device, allowing the assembly to be interchangeable among instruments while retaining its precision operating characteristics.