Showing papers on "Heat sink published in 1992"

Heat sink optimization with application to microchannels

Abstract: The equations governing the fluid dynamics and combined conduction/convection heat transfer in a heat sink are presented in dimensionless form for both laminar and turbulent flow. A scheme presented for solving these equations permits the determination of heat sink dimensions that display the lowest thermal resistance between the hottest portion of the heat sink and the incoming fluid. Results from the present method are applied to heat sinks reported by previous investigators to study effects of their restrictions regarding the nature of the flow (laminar or turbulent), the ratio of fin thickness to channel width, or the aspect ratio of the fluid channel. Results indicate that when the pressure drop through the channels is small, laminar solutions yield lower thermal resistance than turbulent solutions. Conversely, when the pressure drop is large, the optimal thermal resistance is found in the turbulent region. With the relaxation of these constraints, configurations and dimensions found using the present procedure produce significant improvement in thermal resistance over those presented by all three previous studies. >

Exposed die-attach heatsink package

Abstract: A technique for packaging an integrated-circuit die (32) in a conventional molded-plastic package (38) exposes the lead-frame (36) to which the integrated-circuit die (32) is attached so that heat-conducting columns (40, 41) can be directly attached to the lead-frame (36) through vias (42, 43) formed in the molded plastic package (38). The vias (42, 43) expose selected areas (44, 45, 46, 47) of the lead-frame (36) to which are attached the thermally conductive columns (40, 41), which extend to an exterior surface of the molded plastic package (38) so that the lead-frame (36) and the conductive columns provide a path for conduction of heat from the die (32) to the exterior of the package (38).

Reduced stress plastic package

Abstract: A plastic package (10) with a heat sink (11, 27, 28, 32) has a stress relief wall (18, 21, 33) formed on its upper surface. A semiconductor die (12) is mounted on the heat sink (11, 27, 28, 32) such that the top of a semiconductor die (12) is below the level of the top of the wall (18, 21, 33), and the wall (18, 21, 33) absorbs stresses which otherwise would be applied to the semiconductor die (12). The package (10) is simple to fabricate and assemble, and provides a mold lock (23, 24, 31) which serves to hold the plastic material (13) tightly to the heat sink (11, 27, 28, 32). Extra die bond material (26) can be used to increase heat flow without compromising other characteristics of the package (10).

Modular microchannel cooled heatsinks for high average power laser diode arrays

Abstract: Detailed performance results for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or CW operation of fully filled laser diode arrays is made possible at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using an anisotropic chemical etching process. A modular rack-and-stack architecture is adopted for the heatsink design, allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel cooled heatsinks is ideally suited to pump array requirements for high average power crystalline lasers. >

High performance integrated circuit chip package

Abstract: A high performance integrated circuit chip package includes a support substrate having conductors extending from one face to the opposite face thereof and a multilayer wiring substrate on the opposite face of the support substrate for connecting chips mounted thereon to one another and to the conductors. A heat sink includes microchannels at one face thereof, with thermally conductive cushions connecting the one face of the heat sink with the exposed back sides of the chips, to provide a high density chip package with high heat dissipation. The support substrate and heat sink may be formed of blocks of material having thermal expansion matching silicon. The cushions are a low melting point solder, preferably pure indium, and are sufficiently thick to absorb thermal stresses, but sufficiently thin to efficiently conduct heat from the chips to the heat sink.

Heat sink for semiconductor device assembly

Abstract: A first, lower heat sink disposed immediately below and closely adjacent a semiconductor chip (die) in a semiconductor chip assembly is disclosed. The lower heat sink is a flat metallic or ceramic shim. A second, upper heat sink disposed immediately above and closely adjacent the top surface of the semiconductor device is disclosed. The upper heat sink may have a portion in contact with a passivation layer over the top surface of the semiconductor die (device). The second heat sink preferably has a flat surface forming an exterior surface of the semiconductor device assembly. In one embodiment, the second heat sink has pedestals resting atop a plastic layer in a tape-like structure within the semiconductor chip assembly. In a second embodiment, the second heat sink includes an add-on portion that is external to the semiconductor chip assembly. The first heat sink is particularly well-suited to applications wherein the semiconductor chip assembly is mounted to a thermal mass. The second heat sink is particularly well-suited to applications wherein air cooling is available. Each of the first and second heat sinks provide effective cooling, and when used together provide even more effective cooling. Alternatively, the die may be mounted to the top surface of a printed circuit board support structure, the bottom surface of which is provided with a plurality of solder bumps.

Thin planer package for cooling an array of edge-emitting laser diodes

Abstract: A laser diode array (112) includes a plurality of planar assemblies and active cooling of each assembly. The laser diode array (112) may be operated in a long duty cycle, or in continuous operation. A laser diode bar (112) and a microchannel heat sink (120) are thermally coupled in a compact, thin planar assembly (110) having the laser diode bar located proximate to one edge (116). The cooling means (122) includes a microchannel heat sink (120) proximate to the laser diode bar (112) to absorb heat generated by laser operation. To provide the coolant to the microchannels, each thin planar assembly comprises passageways (150-152) that connect the microchannels (120) to inlet and outlet corridors (142). Each inlet passageway (150) may comprise a narrow slot that directs coolant into the microchannels (120) and increases the velocity of flow therethrough. The corridors (140, 142) comprise holes extending through each of the assemblies in the array. The inlet and outlet corridors (140, 142) are connected to a conventional coolant circulation system (122). The laser diode array (112) with active cooling has applications as an optical pump for high power solid state lasers, or by mating the diodes with fiber optic lenses. Further, the arrays can be useful in applications having space constraints and energy limitations, an in military and space applications.

Enhancement of Single-Phase Heat Transfer and Critical Heat Flux From an Ultra-High-Flux Simulated Microelectronic Heat Source to a Rectangular Impinging Jet of Dielectric Liquid

Abstract: Jet impingement is encountered in numerous applications demanding high heating or cooling fluxes. Examples include annealing of metal sheets and cooling of turbine blades, x-ray medical devices, laser weapons, and fusion blankets. The attractive heat transfer attributes of jet impingement have also stimulated research efforts on cooling of high-heat-flux microelectronic devices. These devices are fast approaching heat fluxes in excess of 100 W/cm[sup 2], which have to be dissipated using coolants that are both electrically and chemically compatible with electronic components. Unfortunately, fluids satisfying these requirements tend to possess poor transport properties, creating a need for significant enhancement in the heat transfer coefficient by such means as increased coolant flow rate and phase change. The cooling problem is compounded by a need to cool large arrays of heat sources in minimal volume, and to reduce the spacing between adjacent circuit boards. These requirements place severe constraints on the packaging of jet impingement cooling hardware.

Heat dissipating assembly

Abstract: This invention provides an improved system for removably coupling a conductive heat sink to a chip housing. The heat sink is of the type having a plurality of pins arrayed in a grid pattern and extending perpendicularly from the top surface of a generally square base. The chip housing is of the type having opposite side walls each having latching projections. The heat sink is positioned in conductive thermal communication with an exposed portion of a computer chip or other device which is securely mounted to the housing. A flexible and resilient spring clip is adapted to fit within the passages defined by the spaces between the pins on the heat sink. The flexibility of the spring clip allows portions along opposing walls of the spring clip to be stretched and guided over the latching projections. The resiliency of the spring clip provides a spring bias sufficient to retain the heat sink in conductive thermal communication with the chip element under required working conditions. The resilient forces of the stretched spring clip are not so great as to prevent the quick and easy manual insertion and removal of the spring clip.

Heat sink for electrical circuit components

Abstract: A heat sink for electrical circuit components includes a chill plate which is formed by a front plate and a back plate. The front and back plates are interconnected and cooperate to define passages for liquid coolant. Cooling fins extend from the back plate and are exposed to the atmosphere to conduct heat from the back plate. A pump is mounted on the chill plate and induces a flow of the cooling medium through passages between the front and back plates. An expansion chamber is also disposed between the front and back plates and holds gas which is compressible by the liquid cooling medium to accommodate expansion of the liquid cooling medium.

Apparatus for cooling heat generating members

Abstract: An apparatus for cooling heat generating members such as semiconductor devices on a multichip module. A discharge device discharges cooling liquid for contacting the heat generating members and cooling them. A mixing device mixes the now high temperature cooling liquid, which has cooled the heat generating members, with another portion of the aforesaid cooling liquid still at a lower temperature. As a result, the temperature of the high temperature cooling liquid, which has been heated because it had cooled the heat generating members, can be lowered because the high temperature cooling liquid is mixed with the low temperature cooling liquid. Furthermore, a cooling liquid discharge device is provided for each heat generating member and a mixing device is located between the cooling liquid discharge devices or between heat generating members. In addition, the mixing device has a guide member for guiding the flow.

Integrated heat pipe and circuit board structure

Abstract: A heat pipe structure is incorporated directly into the metal baseplate of a circuit card thereby eliminating thermal contact resistance between the baseplate and the heat pipe assembly. Components are mounted on a copper circuit layer bonded to a dielectric layer in a first portion of the baseplate with a second portion of the baseplate/heat pipe assembly extending into a heat sink/cold plate condensing area for removal of heat generated in the component portion.

Electronic equipment and computer with heat pipe

Abstract: An electronic equipment has heat pipes for radiating heat generated from heat generating electronic parts. The electronic parts are arranged such that electronic parts generating more heat are arranged nearer to a heat radiating portion of each heat pipe to prevent a phenomenon of dryout and radiate the heat efficiently, whereby heat generated from the electronic parts such as LSI chips can be effectively radiated and an excessive rise in temperature of the electronic parts can be suppressed. When the invention is applied to computers, the entire computer size can be reduced.

Semi-rigid heat transfer devices

Abstract: Semi-rigid heat transfer devices (10, 100, 200, 300) are provided for heating or cooling components, such as electrical components, wherein the heat transfer devices (10, 100, 200, 300) are sufficiently flexible to conform to the shapes of the components, but are sufficiently rigid to maintain its overall structural shape. Moreover, the heat transfer devices (10, 100, 200, 300) include at least a frame (12, 202, 302) or support portion (106) thereof and a layer of flexible film (14, 16, 102, 104, 204, 206, 304, 306). The frame and film layer are advantageously heat sealable according to one aspect of the present invention. The degree of flexibility for a particular heat transfer device can be designed in accordance with the specific requirements of particular applications.

A technique for enhancing boiling heat transfer with application to cooling of electronic equipment

Abstract: Particle layering is introduced as an effective and convenient technique for enhancing boiling nucleation on a surface. Because it can be applied without stress or damage to a surface, it can be implemented in immersion cooling, with boiling, of electronic equipment components. Such an enhanced surface, which has an increased number of nucleation sites, shows a decreased level of wall superheat under boiling and an increased critical heat flux relative to superheat and critical heat flux values for an untreated surface. Application of this technique results in a decrease of heated surface temperature and a more uniform temperature of the heated surface; both effects are important in immersion cooling of electronic equipment. >

Method and apparatus for immersion cooling or an electronic board

Abstract: A liquid heat sink is provided that employs natural convection of a liquid coolant (18') to cool a printed circuit board (14) on which are mounted a plurality of heat-generating components (12). In particular, the spacing d between the heat-generating components and a cold plate (20) used to cool the liquid must be such as to provide a Rayleigh number of at least about 1700 in the Rayleigh equation: ##EQU1## In the above equation, g is the acceleration of gravity, β is the volumetric coefficient of expansion of the liquid coolant, T1 is the temperature of the cold plate, T2 is the temperature of the component to be cooled, ν is the kinematic viscosity of the liquid coolant, and α is the thermal diffusivity of the liquid coolant. The novel heat sink of the present invention allows complete immersion of the component in the liquid to provide maximum heat transfer, while at the same time providing a mounting/packaging scheme that allows full utilization of the desired heat transfer properties.

Optimal thermal design of air cooled forced convection finned heat sinks-experimental verification

Abstract: D.B. Tuckerman and R.F.W. Pease (1981) showed that microchannels with water flow could be used to cool VLSI systems. Their work required the flow to be laminar, and the channel system, or fin array, was optimized analytically. Recently, it has been shown that, for some geometries and fluid pressure drops, a lower thermal resistance can be found if the channels are designed to allow turbulent flow. The current work uses the optimization scheme developed by R.W. Knight et al. (1991 and in this issue) to design three air-cooled aluminum finned arrays, which were built and tested experimentally. The thermal performances of the fin array designs, one containing 5 fins, one with 11 fins, and one with the predicted optimum of 8 fins, are compared. All arrays had turbulent flow and pressure drop across them, and all fins were the same length and width. The best thermal performance was obtained with the design predicted to be optimal. The scheme can be applied to a variety of heat sink design applications, including water-cooled microchannels. >

Narrow channel finned heat sinking for cooling high power electronic components

Abstract: Dissipation of the heat produced by the operation of electronic circuitry may be improved by a heat sink which comprises a flat base from which a number of vertical fins extend. The fins are parallel to one another and define a number of parallel channels into which coolant flow is directed. The thermal resistance of the heat sink is optimized by setting fin thickness and channel width parameters to appropriate values. The heat sink may be attached in a heat conductive manner to a heat producing electronic component. One or more of these heat sinked components may be laid out in an in-line or staggered arrangement on a support in the form of a circuit pack. Cooling fluid is delivered to the circuit pack in a variety of ways to cool the heat sinked components. A method of determining the optimum fin thickness and channel width parameters involves determining a relationship between total thermal resistance of the heat sink and combinations of fin thickness and channel width parameters. A contour plot is produced in accordance with the relationship referred to above. The contour plot shows regions of optimum heat dissipation for heat sinks in accordance with the geometry identified here.

Integrated multi-chip module having a conformal chip/heat exchanger interface

Abstract: A multi-chip module having a conformal heat transfer interface to adapt to variations in the height and angle of integrated circuit chips and to achieve a thermal energy path between each chip and a heat sink. The conformal heat transfer interface includes a deformable metallic membrane and a liquid under pressure. The liquid has a high thermal conductivity and provides a pressure for deforming the metallic membrane to compensate for non-coplanarity of the chips. The module integrates the structural support, RF shielding, contamination-protection elements, and the heat-dissipating mechanism that are desired in the design of multi-chip modules. Double-sided cooling of the module significantly improves the thermal characteristics of a module, even in the absence of the conformal heat transfer interface.

Heat sink plate for multiple semi-conductors

Abstract: A heat sink comprising a thin plate made of a heat conducting material, which plate includes a series of small tapered chimneys extending therethrough, the plate being adapted to fit over and parallel to an entire circuit board, thermally connecting with the semiconductors on the board, the chimneys being spaced inbetween the semiconductors and facilitating natural or forced airflow from the area between the plate and the printed circuit board to the area outside by means of the low pressure drop created by their tapering, the heat sink taking very little vertical space in the electronics package including the printed circuit board while providing effective heat dissipation and shielding from electro-magnetic radiation and/or radio frequency interference for the semiconductors on the board.

Multi-system power generator

Abstract: A geothermal power system utilizes a fluid refrigerant capable of changing phase between liquid and gaseous states. The system includes a heat exchanger exposed to a heat source such as earth, water, air, or industrial waste for vaporizing the fluid in the heat exchanger. The heat exchanger includes at least two compartmentalized heat exchanger cells. Each of the heat exchanger cells is disposed in a portion of the naturally occurring heat source, the portions being sufficiently spaced apart such that a temperature of any one portion is substantially unaffected by a temperature of any other portion. The vaporized fluid is directed to a turbine or energy extraction means wherein the gas is expanded and energy is re)eased in the form of mechanical rotation of a shaft. The turbine shaft may be coupled to a generator for converting the mechanical rotational energy to electrical power. The gas discharged from the turbine is cooled/condensed and circulated into an accumulator, with a sensor and a controller for continuously maintaining the optimum amount of refrigerant flowing in the system under particular heat source/heat sink conditions. The liquid refrigerant is then recirculated to the heat exchanger, and the process is performed continuously. A compressor and sensored and controlled accumulator may be utilized in a second and separate refrigerant heat exchange loop with compartmentalized heat exchanger cells if necessary to maintain continuous output from the geothermal power system under all temperature conditions.

Electronics package with improved thermal management by thermoacoustic heat pumping

Abstract: Electronic chips are cooled to an efficient operating temperature by engaging their exposed planar surfaces with a heat sink assembly. The heat sink assembly is a part of the cold end heat sink of a thermoacoustic heat pump that utilizes either traveling wave or standing wave heat pumping to transport heat from the cold end heat exchanger to the warm end heat exchanger, utilizing a coaxial pulse tube refrigerator to pump or transport the heat from the electronic chips and the cold end heat exchanger.

Surface mount heat sink

Abstract: A heat sink for electronic devices which are surface mounted on a printed circuit board includes two side members, a connecting bridge, a foot on each side member which is soldered to a mounting pad on the printed circuit board, a locating element on each side member which engages an aperture in the printed circuit board during assembly, and a group of heat dissipating fingers on each side member. The heat sink can be placed over an electronic device which is surface mounted to the mounting pad on the printed circuit board and the feet of the heat sink can be soldered to the mounting pad simultaneously with the soldering of the electronic device to the mounting pad on the printed circuit board.

Thermal packaging for natural convection cooled electronics

Abstract: A natural convection cooled electronic device utilizing a box-like plastic enclosure surrounding the circuitry of the electronic device. The apparatus further includes aluminum heat sinks fastened in good thermal contact with heat dissipating components of the electronic device, wherein the heat sinks include heat fin members which run parallel to the inner walls of the enclosure and are separated from the walls by an air gap. The inner walls of the enclosure are lined with a layer of thermally conductive material, such as copper foil, which spreads the internal heat flux across the total surface area of the enclosure. The exposed surface of the heat flux spreader layer and the facing surface of the heat fin members are further made semi-rough and stained black to eliminate potential hot spots and to increase radiant heat transfer between the heat sinks and the enclosure. An alternative embodiment includes an electrical insulation layer between the electronic circuitry and the heat flux spreader layer. The insulation layer may include openings to allow contact of the heat flux spreader layer to the electronic circuitry at grounded locations.

Integral dam and heat sink for semiconductor device assembly

Abstract: A metallic or ceramic dam structure surrounding a semiconductor die in a semiconductor device assembly is disclosed. The dam structure forms a cavity containing a potting compound encapsulating the die. The dam structure may also be provided with a flat lid portion, enclosing the cavity and forming a flat, exterior, heat-dissipating surface for the semiconductor device assembly. Further, an additional add-on structure, having heat dissipating fins, may be joined to the dam structure, exterior the semiconductor device assembly, to provide additional heat dissipation. The add-on structure is particularly well-suited to applications where air cooling is available.

Heat sink mounting apparatus

Abstract: A clip having parallel edge frames with pockets at each end and connected by transverse beams is used to removeably secure a heat sink to an orthogonal device package by inserting the corners of the device package in the pockets to secure the heat sink between the transverse beams and the surface of the device package.

Motor control unit with thermal structure

Abstract: A motor control unit having a first semiconductor module circuit for converting an alternating current into a direct current, a second semiconductor module circuit consisting of switching elements for converting the direct current into an alternating current of optional voltage and frequency, and a control circuit for controlling the semiconductor module circuits. The unit has a case that is substantially rectangular in cross section, vertically high and laterally thin with respect to a perpendicular installation surface. Two heat sinks are disposed at the outside of the unit case at the back thereof and are thermally connected to a laminar heat plate that is disposed within the case and in contact with the heat dissipating installation surfaces of the semiconductor modules inside the unit case.