Showing papers on "Heat sink published in 2001"

Assessment of high-heat-flux thermal management schemes

Abstract: This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.

Led integrated heat sink

Abstract: An electrically driven light emitting diode (LED) assembly comprising a light emitting diode ( 12 ), first ( 14 ) and second ( 16 ) electrical leads for conducting electricity to and from the light emitting diode ( 12 ), and a heat sink ( 18 ). The assembly is characterized by the first lead ( 14 ) including the heat sink ( 18 ) for conducting electricity and heat from the light emitting diode ( 12 ) through the heat sink ( 18 ). In other words, the diode ( 12 ) conducts electricity through a heat sink ( 18 ) allowing the diode ( 12 ) to be in electrical conductivity with the heat sink ( 18 ).

Heat transfer apparatus

Abstract: The present invention relates generally to apparatus and methods for the spreading and dissipation of thermal energy from heat-producing components. More particularly, it relates to a heat transfer apparatus and methods particularly useful in the electrical arts. One embodiment of a heat transfer apparatus include but not limited to, a spring-biased member comprising a first side member, a second side member, and a connecting member adapted for spring-biased removable attachment to a heat-producing device. Another embodiment of a heat transfer apparatus is a spring-biased carrier that attaches to a heat-producing device and which carries a member, such as a finned plate. Another embodiment of a heat transfer apparatus is a spring-biased member comprising fingers for conducting thermal energy to a structure. Another embodiment of a heat transfer apparatus is a spring-biased clip used to attach separate heat-spreading/dissipating members, such as a finned plate, against a heat-producing member.

Forced convection boiling in a microchannel heat sink

Abstract: Micromachining technology was utilized to fabricate a transparent microchannel heat-sink system by bonding glass to a silicon wafer. The micro heat sink consisted of a microchannel array, a heater, and a temperature sensor array. This integrated microsystem allowed simultaneous qualitative visualizations of the flow pattern within the microchannels and quantitative measurements of temperature distributions, flow rates, and input power levels. Boiling curves of temperature as a function of the input power were established. No boiling plateau was observed in the boiling curves, consistent with our previously reported data but different from results reported for macrochannel heat sinks. Three stable boiling modes, depending on the input power level, have been distinguished from the flow patterns. Local nucleation boiling was observed in microchannels with a hydraulic diameter as small as 26 /spl mu/m at the lower input power range. At the higher input power range, a stable annular flow was the dominant boiling mode. Bubbly flow, commonly observed in macrochannels, could not be developed in the present microchannels. Consequently, no boiling plateau was detected in the boiling curves.

Optimization of plate fin heat sinks using entropy generation minimization

Abstract: The specification and design of heat sinks for electronic applications is not easily accomplished through the use of conventional thermal analysis tools because "optimized" geometric and boundary conditions are not known a priori. A procedure is presented that allows the simultaneous optimization of heat sink design parameters based on a minimization of the entropy generation associated with heat transfer and fluid friction. All relevant design parameters for plate fin heat sinks, including geometric parameters, heat dissipation, material properties and flow conditions can be simultaneously optimized to characterize a heat sink that minimizes entropy generation and in turn results in a minimum operating temperature. In addition, a novel approach for incorporating forced convection through the specification of a fan curve is integrated into the optimization procedure, providing a link between optimized design parameters and the system operating point. Examples are presented that demonstrate the robust nature of the model for conditions typically found in electronic applications. The model is shown to converge to a unique solution that gives the optimized design conditions for the imposed problem constraints.

Light source using semiconductor devices mounted on a heat sink

Abstract: A semiconductor light source for illuminating a physical space has been invented. In various embodiments of the invention, a semiconductor such as and LED chip, laser chip, LED chip array, laser array, an array of chips, or a VCSEL chip is mounted on a heat sink. The heat sink may have multiple panels for mounting chips in various orientations. The chips may be mounted directly to a primary heat sink which is in turn mounted to a multi-panel secondary heat sink. A TE cooler and air circulation may be provided to enhance heat dissipation. An AC/DC converter may be included in the light source fitting.

Nonuniform temperature distribution in electronic devices cooled by flow in parallel microchannels

Abstract: We fabricated a novel thermal microsystem (simulating a computer chip) consisting of a heater, microchannels, inlet and outlet plena and we studied the effect of the geometry on the flow and heat transfer. The vapor-water two-phase flow patterns were observed in the parallel microchannels through a microscope and high-speed video camera. It was observed that hydraulic instabilities occur. Existence of a periodic annular flow was also observed, which consists of a symmetrically distributed liquid ring surrounding the vapor core. Along the microchannel axis, the periodic dry zone appears and develops. The thermal visualization and temperature measurements of the heated device were carried out using infrared thermography. As long as the flow was single phase liquid, the forced convection heat transfer resulted in a moderate irregularity on the heated chip. These temperature differences do not cause damage to a real electronic device. The steady-state heat transfer for different types of microchannels has been studied also at the range of heat flux where phase change of the working fluid from liquid to vapor took place. Under conditions of flow boiling in microchannels, a significant enhancement of heat transfer was established. In the case of uniform heat flux the hydraulic instabilities lead to irregularity of temperature distribution on the heated chip. In the case of nonuniform heat flux the irregularity increased drastically.

Structures for improving heat dissipation in stacked semiconductor packages

Abstract: Semiconductor packages including at least two semiconductor dies are disclosed. A first die is mounted on a substrate, which may be a metallized laminate or a leadframe. A rigid support structure is mounted on the substrate over the first die. The support structure may be thermally coupled to the substrate, and also may be electrically coupled to the substrate. A second die is mounted on the support structure, which spaces the second die away from the first die. Encapsulant fills the volume within the support structure, including the vertical space between the pair of dies. In an alternative package embodiment, a heat spreader formed of a flexible metal sheet may be thermally coupled between the two stacked dies. The heat spreader transfers heat from the first and second dies to a heat sink of the substrate. The support structure and the heat spreader mitigate the transfer of heat between the first and second dies.

Light emitting diode light source for curing dental composites

Abstract: Light Emitting Diode Light Sources for Dental Curing are disclosed. Some embodiments of the invention include structures such as Light Emitting Diode Array(s), heat sink, heat dissipation, heat pipe, and control circuitry are disclosed.

Void-induced thermal impedance in power semiconductor modules: some transient temperature effects

Abstract: The operation of power semiconductor modules creates thermal stresses that grow voids in the solder die-attach layer. These voids reduce the ability of the die-attach solder layer to conduct heat from the silicon junction to the heat spreader. This results in increased thermal impedance. The effect of accelerated aging on solder bond voiding and on thermal transient behavior is investigated. Commercially packaged TO-247 style MOSFETs are power cycled, imaged, and thermally analyzed to generate a correlation between void percentage and thermal impedance.

Thermal management system

Abstract: The present invention relates to a system for managing the heat from a heat source like an electronic component More particularly, the present invention relates to a system effective for dissipating the heat generated by an electronic component using a thermal management system that includes a thermal interface formed from a flexible graphite sheet and/or a heat sink formed from a graphite article

Thermal component model for electrothermal analysis of IGBT module systems

Abstract: The insulated gate bipolar transistor (IGBT) modules are getting more accepted and increasingly used in power electronic systems as high power and high voltage switching components. However, IGBT technology with high speed and greater packaging density leads to higher power densities on the chips and increases higher operating temperatures. These operating temperatures in turn lead to an increase of the failure rate and a reduction of the reliability. In this paper, the static and dynamic thermal behavior of IGBT module system mounted on a water-cooled heat sink is analyzed. Although three-dimensional finite element method (3-D FEM) delivers very accurate results, its usage is limited by an imposed computation time in arbitrary load cycles. Therefore, an RC component model (RCCM) is investigated to extract thermal resistances and time constants for a thermal network. The uniqueness of the RCCM is an introduction of the time constants based on the Elmore delay, which represents the propagation delay of the heat flux through the physical geometry of each layer. The dynamic behavior predicted by the thermal network is equivalent to numerical solutions of the 3-D FEM. The RCCM quickly offers insight into the physical layers of the components and provides useful information in a few minutes for the arbitrary or periodic power waveforms. This approach enables a system designer to couple the thermal prediction with a circuit simulator to analyze the electrothermal behavior of IGBT module system, simultaneously.

Semiconductor light source using a heat sink with a plurality of panels

Abstract: A semiconductor light source for illuminating a physical space has been invented. In various embodiments of the invention, a semiconductor such as and LED chip, laser chip, LED chip array, laser array, an array of chips, or a VCSEL chip is mounted on a heat sink. The heat sink may have multiple panels for mounting chips in various orientations. The chips may be mounted directly to a primary heat sink which is in turn mounted to a multi-panel secondary heat sink. A TE cooler and air circulation may be provided to enhance heat dissipation. An AC/DC converter may be included in the light source fitting.

Method for making a semiconductor light source

Abstract: A method for making a semiconductor light source for illuminating a physical space has been invented. In various embodiments of the invention, a semiconductor such as a LED chip, laser chip, LED chip array, laser array, an array of chips, or a VCSEL chip is mounted on a heat sink. The heat sink may have multiple panels for mounting chips in various orientations. The chips may be mounted directly to a primary heat sink which is in turn mounted to a multi-panel secondary heat sink. A TE cooler and air circulation may be provided to enhance heat dissipation. An AC/DC converter may be included in the light source fitting.

Modeling of the thermal and hydraulic performance of plate fin, strip fin, and pin fin heat sinks-influence of flow bypass

Abstract: Tests have been conducted in a wind tunnel with seven types of heat sinks including plate fin, strip fin, and pin fin heat sinks. In the case of strip fin, and pin fin heat sinks, both in-line and staggered arrays have been studied. The pin fin heat sinks had circular and square cross-sections. For each type, tests were run with fin heights (H) of 10, 15, and 20 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. In total, 42 different heat sinks were tested. The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB=0.84, 0.53, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH=1, 0.67, and 0.33 while the duct Reynolds number was varied between 2000 through 16500. An empirical bypass correlation has been developed for the different fin designs. The correlation predicts the Nusselt number and the dimensionless pressure drop and takes into account the influence of duct height, duct width, fin height, fin thickness, and fin-to-fin distance. The correlation parameters are individual for each fin design. Further, a physical bypass model for plate fin heat sinks has been developed to describe the bypass effect.

Cooling unit for cooling a heat generating component and electronic apparatus having the cooling unit

Abstract: An electronic apparatus comprises a housing for accommodating a heat generating component and a display unit supported by the housing. A heat receiving head thermally connected to the heat generating component is accommodated inside the housing. A heat radiator is disposed in the display unit. A heat receiving head and the heat radiator are connected to each other through a circulating path for circulating cooling medium. The circulating path is provided with an intermediate cooling unit. Before cooling medium heated by heat transfer by the heat receiving head reaches the heat radiator, the intermediate cooling unit forces cooling medium to be cooled.

Integrated cooling system

Abstract: Systems and methods are described for integrated cooling system. A method includes: circulating a liquid inside a flexible multi-layer tape; and transporting heat between a heat source that is coupled to the flexible multi-layer tape and a heat sink that is coupled to the flexible multi-layer tape. A method includes installing a flexible multi-layer tape in an electrical system, wherein the flexible multi-layer tape includes a top layer; an intermediate, layer coupled to the top layer; and a bottom layer coupled to the intermediate layer, the intermediate layer defining a closed loop circuit for a circulating fluid. An apparatus includes a flexible multi-layer tape, including: a top layer; an intermediate layer coupled to the top layer; and a bottom layer coupled to the intermediate layer, wherein the intermediate layer defines a closed loop circuit for a circulating fluid.

Double-sided cooling for high power IGBT modules using flip chip technology

Abstract: A new technique for the packaging of IGBT modules has been developed. The components are sandwiched between two direct bond copper (DBC) substrates with aluminum nitride. Wire bonds are replaced with flip chip solder bumps, which allows cooling of components on both sides. Microchannel heat sinks are directly integrated in the package to decrease the thermal resistance of the module. Thus, a very compact module with high thermal performance is obtained. A prototype with two insulated gate bipolar transistors (IGBTs) and four diodes associated in parallel was realized and tested. In this paper, the innovative packaging technique is described, and results of thermal tests are presented.

Piezoelectric micro-transducers, methods of use and manufacturing methods for same

Abstract: Various micro-transducers incorporating piezoelectric materials for converting energy in one form to useful energy in another form are disclosed. In one embodiment, a piezoelectric micro-transducer can be operated either as a micro-heat engine, converting thermal energy into electrical energy, or as a micro-heat pump, consuming electrical energy to transfer thermal energy from a low-temperature heat source to a high-temperature heat sink. In another embodiment, a piezoelectric micro-transducer is used to convert the kinetic energy of an oscillating or vibrating body on which the micro-transducer is placed into useful electrical energy. A piezoelectric micro-transducer also is used to extract work from a pressurized stream of fluid. Also disclosed are a micro-internal combustion engine and a micro-heat engine based on the Rankine cycle in which a single fluid serves as a working fluid and a fuel.

Outdoor unit of air conditioner

Abstract: An air conditioner outdoor unit (1) comprises a case having a rectangular shape and composed of side panels (4, 4,--) in which a machine chamber (3) and a heat exchanger chamber (2) are defined so as to be vertically aligned, with the heat exchanger chamber disposed above the machine chamber (3) and sectioned by a partition plate (12) which also acts as a drain pan, the side panels surrounding the heat exchanger chamber are formed with air suctions ports (4a, 4a --). The outdoor unit (1) further comprises a heat exchanger unit (17, 18) having four side wall sections of which at least two opposing two sections are inclined inwardly by a predetermined angle with respect to inner surfaces of the side panels to which the air suction ports are formed. The outdoor unit case also contains a duct unit (20) arranged in association with the drain pan (12) for discharging drain and cooling an electrical part such as a heat sink (22).

Semiconductor device attaining both high speed processing and sufficient cooling capacity

Abstract: A semiconductor device includes two or more semiconductor modules which are stacked up into three-dimensional structure Each semiconductor module includes a wiring board, one or more IC chips which are mounted on the wiring board, and one or more heat sinks which are attached to the IC chips via a thermal-conductive adhesive and are forcedly cooled by a coolant flowing through channels which are formed therein The wiring board of each semiconductor module is provided with sockets having I/O pins and concavities Electrical connection between adjacent semiconductor modules of the semiconductor device is established by inserting the I/O pins of the sockets of one semiconductor module into the concavities of the sockets of the other semiconductor module The channels in the heat sink are implemented by a plurality of channel grooves which are generated between a plurality of fins which are formed in a cavity inside the heat sink at predetermined intervals The coolant is supplied to the channel grooves from outside and the IC chips are forcedly cooled by the coolant Therefore, enough cooling capacity is ensured by use of low-profile heat sinks, thereby both high processing speed (due to high packing density and short signal lines between IC chips) and sufficient cooling capacity are attained

Electronic enclosure cooling system

Abstract: A cooling apparatus using 'low profile extrusions' is disclosed. The cooling apparatus of the present invention may be incorporated into a closed loop liquid cooling system which is particularly well suited to heat removal from electronic components in applications where space is limited. A cooling system in accordance with the present invention is illustrated for use in a typical wireless telecommunication bases station for removing heat from power amplifiers and other electronic components. Cooling is carried out by drawing heat away from the electronic components and into at least one low profile extrusion attached directly to the heat generating components or a heat sink, and transferring the removed heat to a cooling fluid circulating through a plurality of micro tubes or channels within each low profile extrusion. The cooling fluid is subsequently pumped through a liquid-to-air heat exchanger, to reject the removed heat into the atmosphere, prior to being recirculated through each of the low profile extrusions.

Enhanced thermal dissipation integrated circuit package

Abstract: In one aspect, the present invention relates to an integrated circuit package includes a scmiconductor die electrically connected to a substrate, a heat sink having a top and a side portion, the heat sink further including an extending finger when viewed from a top of the package, the extending finger including the side portion of the heat sink, a thermally conductive element thermally coupled with an interposed between both the semiconductor die and the heat sink, wherein the thermally conductive element does not directly contact the semiconductor die, and an encapsulant material encapsulating the thermally conductive element and the heat sink such that the top portion and the side portion of the heat sink are exposed to the surroundings of the package.

High heat flux heat pipe mechanism for cooling of electronics

Abstract: This paper discusses an advanced heat pipe mechanism that has the potential of achieving heat flux capabilities over 250 W/cm/sup 2/. The mechanism utilizes thermally driven pulsating two-phase flow to achieve high heat flux capability and heat transfer coefficient. A simplified hydrodynamic model in was developed to guide the proof-of-concept heat pipe design. A more detailed numerical model was also developed and will be solved to predict the heat pipe's thermal performance. Test results of proof-of-concept heat pipes verified the heat flux capability of the advanced mechanism and the accuracy of the simplified model. Pulsating heat pipes are feasible approaches to removing increasing heat dissipation densities in electronic equipment.

Graphite-based heat sink

Abstract: The present invention relates to a system (10) for managing the heat from a heat source like an electronic component. More particularly, the present invention relates to a system (10) effective for dissipating the heat generated by an electronic component using a heat sink formed from a compressed, comminuted particles of resin-impregnated flexible graphite mat or sheet.

Printed circuit board with integral heat sink for semiconductor package

Abstract: A low-cost printed circuit board for a semiconductor package having the footprint of a ball grid array package has an integral heat sink, or “slug,” for the mounting of one or more semiconductor chips, capable of efficiently conducting away at least five watts from the package in typical applications. It is made by forming an opening through a sheet, or substrate, of B-stage epoxy/fiberglass composite, or “pre-preg,” then inserting a slug of a thermally conductive material having the same size and shape as the opening into the opening. The slug-containing composite is sandwiched between two thin layers of a conductive metal, preferably copper, and the resulting sandwich is simultaneously pressed and heated between the platen of a heated press. The heat and pressure forces the resin to the surface of the composite and into the space between the slug and the walls of the composite, where it solidifies, bonding the edges of the slug to the substrate within the opening and adhering the conductive layers to the upper and lower surfaces of the substrate. The resulting laminate can thereafter be processed as a convention printed circuit board to incorporate conventional circuit board features, e.g., circuit traces, wire bonding pads, solder ball mounting lands, and via holes.

Power module package having insulator type heat sink attached to rear surface of lead frame and manufacturing method thereof

Abstract: A power module package in which a heat sink made of an insulating material is attached directly to a second surface of a lead frame, on which a down set is provided, and exposed to the outside, and a manufacturing method thereof are provided. A general rectangular plate or pre-bent plate may be used as the heat sink. The heat sink may be attached during a sealing process or through a separate process performed after the sealing process. The power module package has an improved heat radiation characteristic.

PBGA substrate for anchoring heat sink

Abstract: In accordance with the objectives of the invention a new method is provided to position and secure a heat sink over the surface of a semiconductor device mounting support, the latter typically being referred to as a semiconductor substrate. A plurality of recesses is created in the surface of the substrate over which the heat sink is to be mounted. The heat sink is (conventionally and not part of the invention) provided with dimples that form the interface between the heat sink and the underlying substrate. The dimples of the heat sink are aligned with and inserted into the recesses that have been created by the invention in the underlying substrate for this purpose, firmly securing the heat sink in position with respect to the substrate.