Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K7/00—Constructional details common to different types of electric apparatus
  • H05K7/20—Modifications to facilitate cooling, ventilating, or heating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
  • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
  • H01L23/467—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids by flowing gases, e.g. air
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

• the invention covered by this application is related to devices intended for coolin ⁇ electronic devices by removing heat by a flow of gas, in particular, air flow, said flow being produced by a blower.
• the most widespread devices are the ones that comprise a heat exchanger represented by a heat sink, on one surface of which an electronic device (for instance, semiconductor device or computer processor) is installed, while another surface is made in the form of heat dissipating surface.
• the airflow is produced by a blower (axial fans may serve as a blower).
• the design of the device described in US patent Ne 5867365 comprises an axial fan that produces a flow passing by heat exchanging channels of the heat sink.
• the majority of inlets to heat exchanging channels are located just opposite the axial fan's impeller with a certain number of said channels being placed radially in relation to fan axle.
• US patent JN° 5661638 also involves the application of an axial fan.
• Specific embodiment of device claimed in said patent involves such placement of heat exchanging channels of the heat sink that they are located centrally-symmetrically about the fan axle.
• the heat exchanging channels are made of spiral-like shape and bent backwards in the direction of blower rotation.
• the fan is installed in a recess made in the heat sink body.
• the axial fan produces sufficiently high air pressure.
• the conditions for cooling the central part of the heat sink located underneath the fan are unfavorable. In this case non-uniform cooling of the heat sink and electronic device (in our case, processor) will take place.
• Int.Cl. H05K 7/20 offers a design employing a centrifugal blower that is installed to the side of the heat sink.
• the cooling airflow passes by rectilinear heat exchanging channels of the heat sink.
• centrifugal blower to the side of the heat sink increases device size. This is so because such location of centrifugal blower leads to insufficient coordination between the direction of channel inlets and direction of airflow supplied from the blower.
• the loss in airflow energy results in the reduction of airflow motion speed in heat exchanging channels and in the decline of heat exchange efficiency. A portion of energy is also expended on friction against the casing, in which the blower is enclosed.
• Device design comprises a centrifugal fan enclosed in the casing and installed above the heat exchanging channels that are made divergent. Another heat sink surface is made so that the possibility of thermal contact with an electronic device is provided for.
• the inlet of the centrifugal fan faces the heat sink. The fan produces an airflow that passes by heat exchanging channels and then gets sucked into the inlet of the centrifugal fan.
• the engineering problem to be solved with the help of the invention being claimed herein is the development of a cooler for electronic devices that ensures more uniform cooling of electronic devices due to more effective cooling of the central part of the heat exchange element and the reduction of cooling device size.
• a cooler for electronic devices comprises a heat exchange element (i.e. heat sink) with divergent heat exchanging channels made on its one side, while its other side is made so that a possibility of thermal contact with an electronic device is provided for, and a centrifugal blower installed on the heat exchange element in such a way that it provides for the passing of cooling flow by heat exchanging channels.
• a heat exchange element i.e. heat sink
• divergent heat exchanging channels made on its one side, while its other side is made so that a possibility of thermal contact with an electronic device is provided for
• a centrifugal blower installed on the heat exchange element in such a way that it provides for the passing of cooling flow by heat exchanging channels.
• the centrifugal blower is installed in the center of symmetry of heat exchanging channels. It supplies cooling flow (for instance, airflow) to the central part of heat exchange element. Since the blower impeller is located right opposite the inlets of said heat exchanging channels, the cooling flow is then supplied to channel inlets and as it moves by said channels it cools the heat exchange element down.
• cooling flow for instance, airflow
• centrifugal blower Since the centrifugal blower is installed at the same level as the heat exchanging channels are, the size of the device in height is reduced and the cooling flow is directed into the heat exchanging channels without energy expenditures on turning the flow (from axial direction to the radial direction). The latter is explained by the fact that flow turn is effected owing to the properties of centrifugal blower design.
• the above-mentioned specific features of the device claimed herein provide for a special cooling pattern, which is characterized by the fact that the hottest part of the heat exchange element (namely, its central part) gets cooled first, and, as compared to the above-described prototype, the entire cooling process proceeds more evenly and without losses that are caused in said prototype by flow turn and friction when the cooling flow (going from the impeller) enters the heat exchanging channels.
• a blower of lesser power and size it is advisable that centrifugal blower be equipped with an impeller of drum type.
• the impeller has wide enough suction hole that makes it possible to produce a powerful enough flow to cool the central part of the heat exchange element well.
• a centrifugal blower with a drum-type impeller has minimal size and rotational speed as compared to centrifugal blowers with an impeller of other type.
• the heat exchanging channels can be made in the form of rows of profiled elements.
• these elements can me made in the form of needles.
• the heat exchanging channels may be made spiral-like and bent in the direction of centrifugal blower rotation. This will provide for the prolonged contact between the airflow and heat exchange element surface.
• the heat exchanging channels may be made of constant width. This will make it possible to ensure the constancy of speed at which the airflow blows the surfaces of heat exchanging channels over. Besides, making heat exchanging channels of constant width would enable one to attain the maximum "density" of heat exchanging channels on the heat exchange element surface, which would result in obtaining greater heat exchange area.
• the surface underneath the suction hole of the centrifugal blower may be made needle- shaped.
• This part of the heat exchange element is in essence located inside the centrifugal blower - in the area of the main airflow.
• Semiconductor device or processor is installed in the recess formed by the concave part of the heat exchange element. This concave part of the heat exchange element goes into the central part of blower impeller, which fact also decreases the size.
• the above-indicated specific features of device design results in the fact that cooling flow is supplied first to the central part of the heat exchange element, which is the hottest part. Cooling of this pan proceeds more evenly and without losses expended on flow turn and friction when the cooling flow (going from the impeller) enters the heat exchanging channels.
• the surface of the bent part of the heat exchange element i.e. the surface facing the inlet opening of the centrifugal blower
• the surface of the bent part of the heat exchange element may be made profiled in such a way that a developed heat exchange surface is produced (for instance, needle-shaped surface), e form of rows of profiled elements.
• This part of the heat exchange element is in essence located inside the centrifugal blower - in the area of the main airflow. With such an arrangement of the heat exchange element there will be practically no extra losses for the flowing over the needles, while heat exchange will be considerably improved.
• centrifugal blower impeller with a radial gap of no less than 0.03d (where d is the diameter of centrifugal blower impeller) in relation to the inlets of the heat exchanging channels.
• the heat exchanging channels may be covered with a plate from above. In this case the cooling airflow will propagate only along the channels.
• the cooler for electronic devices in conformity with the second option is made as follows.
• the device comprises a heat exchange element (i.e. heat sink) with divergent heat exchanging channels made on its one side, while its other side is made so that a possibility of thermal contact with an electronic device is provided for, and a centrifugal blower installed on the heat exchange element in such a way that it provides for the passing of cooling flow by heat exchanging channels.
• a heat exchange element i.e. heat sink
• divergent heat exchanging channels made on its one side, while its other side is made so that a possibility of thermal contact with an electronic device is provided for
• a centrifugal blower installed on the heat exchange element in such a way that it provides for the passing of cooling flow by heat exchanging channels.
• a disk-type centrifugal blower with at least one disk is used in the design.
• the disks are installed in such a manner that the edge of disk surface facing the heat exchange element is located opposite the inlets to the heat exchanging channels.
• the centrifugal blower supplies cooling flow (for instance, airflow) to the central part of the heat exchange element, which fact facilitates the effective cooling of the hottest part of the heat exchange element. Transfer of energy from blower disk to the airflow proceeds due to the friction forces.
• the airflow blows the central part of the heat exchange element over not only in the radial direction, but also in the tangential one, due to which fact an additional increase in airflow speed in the central part of the device takes place and extra gain in cooling efficiency is attained.
• blower disk surfaces facing the heat exchange element are located opposite the inlets to the heat exchanging channels, the cooling flow is supplied to said inlets and as the airflow passes by the channels it cools the heat exchange element down.
• the disk-type centrifugal blower generates radial component of the cooling flow, and said radial component matches the inlets to the heat exchanging channels well.
• the disk-type centrifugal blower is characterized by small size (in terms of height) while being effective enough. In addition, it is also characterized by minimal noise level as compared to other types of centrifugal blowers, all other factors being equal.
• the above-mentioned specific features of the device claimed herein provide for a special cooling pattern, which is characterized by the fact that the hottest part of the heat exchange element (namely, its central part) gets cooled first, and, as compared to the above-described prototype, the entire cooling process proceeds more evenly and without losses that are caused in said prototype by flow turn and friction when the cooling flow
• the surface of at least one of the disks of the disk-type centrifugal blower (facing the heat exchange element) may be equipped with radial fins that increase the radial component of the airflow.
• axial blower blades may be installed on at least one of the disks of the centrifugal blower near its central opening, said blades being attached to the disk.
• the blades may be installed on one disk or on several disks. Installation of axial blower blades near the central opening of the disk increases the pressure of cooling airflow in the central part of the heat exchange element with the blower capacity being the same.
• the axial blower blades may be formed by straps that secure disk on the axle of the centrifugal blower.
• the heat exchange element underneath the blower may be made bent in the direction to the blower so that the bent part of the heat exchange element is located underneath the inlet of disk blower.
• the overall size of the device is reduced (because an electronic device fits into the recess) and cooling process is improved (because the hottest central part is blown over with a portion of flow passing at a higher speed).
• the heat exchanging channels can be made in the form of rows of profiled elements.
• these elements can me made in the form of needles.
• the heat exchanging channels may be made spiral-like and bent in the direction of centrifugal blower rotation. This will provide for the prolonged contact between the airflow and heat exchange element surface.
• the heat exchanging channels may be made of constant width.
• the surface of the heat exchange element part facing the inlet of the centrifugal blower may be made profiled in such a way that a developed heat exchange surface is produced (for instance, it may be made needle- shaped). This part of the heat exchange element is located in the area of the main airflow. Therefore, it gets cooled effectively. With such an arrangement of the heat exchange element there will be practically no extra losses for the flowing over the needles, while heat exchange will be considerably improved.
• the heat exchanging channels may be covered with a plate from above secured to the surface of the heat exchange element. In this case the entire cooling airflow will propagate only along the channels, which fact also facilitates the improved heat exchange.
• Fig. 1 general view of the first design option of the device claimed herein (with heat exchanging channels being arranged radially);
• Fig. 2 a sample design of radially diverging heat exchanging channels
• Fig. 3 a sample design of radially diverging spiral-like heat exchanging channels
• Fig. 4 a sample design of spiral-like heat exchanging channels of constant width
• Fig. 5 an illustration to geometric relationships needed for the calculation of the profile of spiral-like heat exchanging channels of constant width
• Fig. 6 - a sample design of heat exchanging channels formed by rows needle- shaped profiled elements
• Fig. 7 - a sample design of the device with a centrifugal blower fixed to the axle and a plate covering heat exchanging channels from the above;
• Fig. 8 - a cross-section of the claimed device shown in Fig. 7 (in accordance with the first design option) with an impeller of a drum-type centrifugal blower and a heat exchange element bent underneath the blower;
• Fig. 9 a sample design of radial heat exchanging channels with a heat exchange element bent underneath the blower (in accordance with the first device design option);
• Fig. 10 a sample design of the claimed device (in accordance with the second device design option) with a centrifugal blower having several disks;
• Fig. 1 1 a sample design of radial heat exchanging channels of the heat exchange element (in accordance with the second device design option);
• Fig. 12 - a sample design of the claimed device (in accordance with the second device design option) with a centrifugal blower having one disk;
• Fig. 13 - a centrifugal blower disk;
• Fig. 14 - a sample design of the claimed device (in accordance with the second device design option) with a centrifugal blower disk, on which radial fins are installed;
• Fig. 15 - a centrifugal blower disk with radial fins (bottom view);
• Fig. 16 - a sample design of the claimed device (in accordance with the second device design option) with a centrifugal blower disk, in the area of the central opening of which axial blower blades are installed;
• Fig. 17 - a centrifugal blower disk with axial blower blades
• Fig. 18 - a cross-section of the centrifugal blower disk shown in Fig. 17 (in the area of axial blower blade).
• the cooler for electronic devices (Fig. 1 and Fig. 2) comprises a heat exchange element 101 with divergent heat exchanging channels 103 made on its one surface 102, while its other surface 104 is made so that a possibility of thermal contact with an electronic device (not shown in Fig. 1) is provided for.
• the device also comprises a centrifugal blower 105 installed on the heat exchange element 101 in the center of symmetry 106 in relation to heat exchanging channels 103.
• Fig. 1 and Fig. 2 present radially diverging heat exchanging channels 103.
• Impeller 107 of centrifugal blower 105 is placed opposite inlets 108 of heat exchanging channels 103.
• Sample designs of centrifugal blower 105 having drum-type impeller 107 are shown in Fig. 6 and Fig. 9.
• Such drum-type centrifugal blowers are characterized by the fact t hat the value of the relation of impeller inner diameter to its outer diameter is no less than 0.75.
• heat exchanging channels 103 may be made spiral and bent over in the direction of rotation of centrifugal blower 105.
• One more embodiment of device design is characterized by the fact that heat exchanging channels 103 are of constant width.
• inlets 108 of heat exchanging channels 103 are oriented in the direction of propagation of the output flow produced by impeller 107 of centrifugal blower 105. It is best to orient the inlets of heat exchanging channels in such a way that the angle between the axis of heat exchanging channel inlets and the direction of incoming airflow produced by impeller 107 will lie within the range ⁇ 5° (see Fig. 5).
• Fig. 5 shows heat exchanging channel 103 formed by two fins 109 (arc AB and arc CD) and corresponding geometric constructions needed for the calculation of the profile of heat exchanging channels of constant width.
• point E of arc AB located at distance r from center of symmetry O and point F (corresponding to said point E) of arc CD [the distance between two said points t(r) represents the width of heat exchanging channel]
• point G of arc CD located also at distance r from the center of symmetry O is determined.
• Distance a( ) between point E and point G for a great number of heat exchanging channels Z is approximately equal to the length of arc EG - i.e. a(r) « 2 ⁇ r I Z .
• t(r) may be defined as t(r) ⁇ a(r) • sm ' [b(r) ⁇ .
• T const
• the values of angle b(r) thus determining the profile of a heat exchanging channel.
• the values of angle b(r) were determined, said values being within the
• the surface of heat exchange element 101 located underneath the suction inlet of centrifugal blower 105 is made needle-shaped, where 110 - are needles.
• impeller 107 of centrifugal blower 105 is installed with radial gap 111, the value of which is no less than 0.33d, where d is the diameter of impeller 107 of centrifugal blower 105.
• Heat exchanging channels 103 may be formed by the rows of profiled elements of circular, rectangular and other cross section.
• the said profiled elements may be made so that they are located immediately adjacent to one another (as shown in Fig. 6) where they are made in the form of needles 112.
• these profiled elements may be produced by making saw cuts in solid fins that make up channels 103 (for instance, in fins 109 - see Fig. 4).
• heat exchange element 101 may be made by different methods (for instance, by casting or milling).
• Centrifugal blower 105 may be secured to axle 113 by means of bearing 114 (see Fig. 7). To ensure that the entire forced airflow passes by heat exchanging channels 103, the latter are covered by plate from the above. In this case plate 115 locks axle 113 by means of straps 116.
• the central part 117 of heat exchange element 101 located underneath blower 105 is made bent over. Bent part 118 of heat exchange element 101 is located opposite the centrifugal blower inlet 106 - in the central part 117 of impeller 108.
• the claimed device in accordance with the first design option operates in the following manner.
• Impeller 107 of centrifugal blower 105 When impeller 107 of centrifugal blower 105 rotates (see Fig. 1) the airflow at first blows over the central part of heat exchange element 101, including its needles 110. Intensive heat exchange proceeds in this area of heat exchange element 101, which is the hottest area of said heat exchange element. Impeller 107 of centrifugal blower 105 supplies the airflow to inlet 108 of heat exchanging channels 103. In the case when heat exchanging channels 103 are made spiral-like and bent in the direction of rotation of blower 105 (see Fig. 3 and Fig. 4) the airflow is directed to channels 103 without deceleration, which means that there is no loss in airflow speed when it enters channel 103.
• the airflow speed in heat exchanging channels 103 of constant width (see Fig. 4) is kept constant. Heat exchange between heat exchange element 101 and airflow takes place when the latter passes by heat exchanging channels 103. As a result of this heat exchange process, an electronic device being in thermal contact with heat exchange element 101 gets cooled down.
• the cooler for electronic devices (Fig. 10 and Fig. 11) comprises a heat exchange element 201 with divergent heat exchanging channels 203 made on its one surface 202, while its other surface 204 is made so that a possibility of thermal contact with an electronic device 205 is provided for.
• the device also comprises a centrifugal blower
• a disk-type centrifugal blower 206 with at least one disk 207 is used in the design.
• Fig. 10 presents a sample design of centrifugal blower 206 with four disks 207.
• Disks 207 are installed in such a manner that the edge 208 of each disk surface facing the heat exchange element 201 is located opposite inlets 209 to the heat exchanging channels 203.
• a cross section of the device having radial heat exchanging channels 203 is shown in Fig. 11.
• heat exchange element 201 may be made of small height.
• the surface of disk 207 facing heat exchange element 201 may be equipped with radial fins 210 (see Fig. 14 and Fig. 15).
• Heat exchange element 201 underneath the blower may be made bent - as is shown in Fig. 14 - in such a manner that the bent part of heat exchange element is located opposite the central opening 205 of disk 207 of centrifugal blower 206.
• Axial blower blades 211 fixed to disk 207 may be installed in the area of central opening 215 of disk 207.
• Fig. 16 presents an example of device embodiment with blades 211 installed on one disk 207.
• blades 211 may also serve as straps 212 securing disk to axle 213 of blower 206.
• the divergent heat exchanging channels may be made spiral-like (see Fig. 3).
• heat exchanging channels may be made of constant width (see Fig. 4).
• Heat exchanging channels may be formed by rows of profiled elements - for instance, needles (see Fig. 6).
• the surface of the part of heat exchange element 201 located underneath inlet 215 of disk-type blower 206 may be made profiled (for instance, needle-shaped - as shown in Fig. 10 - Fig. 12, Fig. 14 and Fig. 16, where 216 - needles).
• heat exchange element 101 or 201 may be made by different methods - for instance, by casting or milling.
• Centrifugal blower 206 can be secured to axle 213 (see Fig. 10, Fig. 12, Fig. 14, and Fig. 16) by means of bearing 219.
• plate 217 has an opening (intended to let the air pass through), Besides, plate 217 secures axle 213 to heat exchange element 201.
• the claimed device in accordance with the second design option operates in the following manner.
• the airflow produced by disk 207 propagates not only in radial direction, but also in tangential direction. Fins 210 (Fig. 14 and Fig. 15) installed on disk 207 augment the radial component of the airflow.
• blades 211 of axial fan are installed in the area of the central opening 215 of disk 207 (Fig. 16 - Fig. 18) said blades produce additional pressure of airflow, thus facilitating better cooling of the central part, and hence cooling of entire heat exchange element 201.
• the present invention may be used for the purpose of cooling electronic devices (primarily - semiconductor devices), microcircuit chips and microprocessors.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
• Thermal Sciences (AREA)
• Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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• 2000
  • 2000-11-22 TW TW089124765A patent/TWI222344B/zh active
  • 2000-12-07 KR KR1020017010058A patent/KR20010112263A/ko not_active Application Discontinuation
  • 2000-12-07 WO PCT/US2000/033145 patent/WO2001043519A1/en active Application Filing
  • 2000-12-07 CN CN00805637A patent/CN1345527A/zh active Pending
  • 2000-12-07 AU AU20668/01A patent/AU2066801A/en not_active Abandoned

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