Classifications

• • 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
  • H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
  • H01L23/427—Cooling by change of state, e.g. use of heat pipes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
• • 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 present invention relates to heat dissipation devices and more particularly to the connection of such devices to a thermal source .
• Heat sinks are widely used devices that dissipate, or in some case, absorb, heat from objects that need to remain cool, such as machinery or computer equipment.
• One type of heat sink comprises a block of heat conductive material, or evaporative plate, with a tunnel or bore machined through it. A heat dissipating pipe is inserted through this tunnel in order to absorb and dissipate the heat conducted to it through the heat conducting material of the surrounding heat plate.
• the heat plate is attached to the object that requires cooling, such as, for example, a wall of a computer cabinet or the mounting of an IC in a laptop computer. An example of this type of heat sink is shown in FIG.
• this adhesive material 103 is inserted first in order to cover the walls of the tunnel.
• the heat pipe 105 is inserted afterwards, it displaces some ' of the adhesive material 103 and results in a less than desirable coupling region.
• FIGS. 2A and 2B One solution, which is shown in the perspective and cross-sectional views of FIGS. 2A and 2B, respectively, is a heat sink where an open channel 201, as opposed to a closed tunnel 101, is formed in heat plate 210 with channel 201 having a diameter substantially equal to the diameter of the pipe 205.
• an adhesive 203 can be applied directly to channel 201 and pipe 205 can then be positioned in the channel 201 without displacing the adhesive 203.
• a drawback to this approach is that a significant amount of pipe surface area 208 is not in contact with the heat plate, thus resulting in a less than optimal heat transfer.
• FIGS. 3A and 3B Another solution proposed in U.S. Patent 5,826,645 to Meyer, IV et al . is shown in the perspective and cross-sectional views of FIGS. 3A and 3B, respectively.
• the heat pipe 305 is held in place by two extension tabs 320 and 321.
• extension tabs 320 and 321 are vertical to the surface of the heat sink, as shown in FIG. 3B.
• extension tabs 320 and 321 are bent down ' to contact and hold in place heat pipe 305, as shown in FIG. 3A.
• Filler material 326 which may be a heat conductive adhesive, solder paste or lubricant, fills up the region between heat pipe 305 and extension tabs 320 and 321.
• extension tabs are pressed against the side of the heat pipe, and might rupture the sides of the heat pipe.
• the large volume of filler material placed on both sides of the heat pipe is inefficient and wastef l .
• One object of the present invention is to provide a heat sink assembly that can effectively hold the heat pipe in place while providing for an efficient transfer of heat between the conductive material and the . heat pipe.
• Another object of the present invention is to provide a heat sink assembly in which the bonding material economically and efficiently connects the heat pipe with the inner surface of the heat plate.
• Yet another object of the present invention is to provide a heat sink assembly in which the bonding material is easily applied and spread (wicking) between the heat pipe with the inner surface of the heat plate.
• a heat sink assembly having a heat block constraining a heat pipe within an elliptical or circular channel having a transverse slot which opens onto the surface of the heat block, thereby allowing for easier and more efficient application of bonding material and more efficient heat transfer .
• the present invention is also directed to a method for forming a heat transfer assembly by forming in a channel in a heat plate, forming a slot in the surface of the heat plate along the length of the channel, inserting a heat pipe into the channel, and disposing heat conductive adhesive material in the gap between the channel and the heat pipe through the slot.
• FIG. 1 is a perspective view of a drilled through heat sink according to the prior art
• FIGS. 2A and 2B are the perspective and cross- sectional views, respectively, of a half open heat sink according to the prior art
• FIGS. 3A and 3B are the perspective and cross- sectional views, respectively, of a tabbed heat sink according to the prior art
• FIGS. 4A and 4B are the perspective and cross- sectional views, respectively, of a preferred embodiment according to the present invention.
• the presently preferred embodiment of the present invention consists of a heat conductive material block (or heat plate) 410 having a drilled or milled tunnel or channel 401 that has a transverse slot 450 formed in the surface of the heat plate above the channel 401.
• the channel 401 and/or slot 450 can be formed via a molding process, via drilling techniques, or other machinery techniques as are well-known in the art.
• the diameter of the channel is larger than the width of the transverse slot 450 and is sized to accept a heat pipe 405 while providing additional space for allowing application of a thermally conductive adhesive material 403 to the channel walls to bond the heat pipe 405 to the channel walls of the heat plate 410, as discussed more fully below.
• a thermally conductive adhesive or bonding agent 403 is used to thermally couple the heat pipe 405 with the channel 401. This is accomplished by applying the adhesive or bonding agent 403 through the slot 450 into a gap 407 formed between the heat pipe 405 and the channel 401.
• the bonding agent 403 is a thermally conductive adhesive solder paste, it could be applied through slot 450 to the top portion of channel 401. Then, the heat sink assembly would be heated, causing the solder to flow downward along the sides of the pipe 405.
• An efficient thermal contact results when the solder flows between the sides of heat pipe 405 and all or substantially all of the contact area between the heat pipe 405 and the walls of channel 401, thereby filling the gap 407.
• the thermally conductive adhesive 403 can be in a preform or paste that is applied to the gap 407, either before or after the heat pipe 405 is disposed in the channel 401, or may be disposed by pressure directly into the gap 407 via the slot 450 once the pipe 405 is in place.
• the preform or paste will be cured in the gap 407 by heating the heat sink assembly to allow a preform to flow or by applying a paste or preform and then heating the assembly.
• the transverse slot 450 is made along the length of the channel 401 for providing access thereto.
• Heat pipe 405 is enclosed by channel 401 to almost its full circumference thus insuring that heat pipe 405 is properly constrained by and contained within the channel walls.
• the transverse slot 450 has a
• the dimension of the transverse slot 450 prevents the pipe 405 from being removed from the channel 401 in a direction perpendicular to the channel length.
• the transverse slot 450 can be formed via a molding process, via drilling techniques, or other machinery techniques as are well-known in the art .
• heat pipe 405 is preferably substantially circular in cross-section
• the channel 401 of the preferred embodiment has a slightly elliptical cross-section, thus insuring that bonding material may be effectively inserted through transverse slot 450 during assembly.
• the cross- sections of both .heat pipe 405 and channel 401 may take a variety of closed curvilinear shapes, from circles to ellipses and ovals.
• preferred embodiments of the present invention maintain the appropriate interface dimension between the heat pipe and the tunnel walls for maximizing heat transfer.
• the channel encloses the heat pipe to almost the full cross-sectional circumference, there is an increased pipe surface area for bonding between the heat pipe 405 and the plate 410, thus insuring a maximum amount of heat transfer.
• the transverse slot 450 allows for easy application of an adhesive 403 along the top and sides of the heat pipe that are exposed in the channel opening.
• a suitable adhesive may be an epoxy or solder paste, or other material known by those having ordinary skill which possess the appropriate thermally-conductive properties for thermally coupling and binding the pipe 405 to the plate 410.
• the gap 407 is provided between the outer surface of the heat pipe and the channel walls in which the solder or epoxy is applied in a known manner for providing optimum wicking action therebetween, such as when the assembly is heated to allow the solder to flow.
• there is effective wicking action of the solder or epoxy to cover the full surface of the heat pipe enclosed in the channel gap.
• a heat sink assembly according to the present invention can effectively hold a heat pipe in place, while providing for a more efficient transfer of heat between, the heat plate and the heat pipe. Furthermore, the bonding material in a heat sink assembly according to the present invention is easily applied through the slot 450 and spread (wicked) between the heat pipe with the inner surface of the channel, thereby providing an economic and more efficient heat transfer connection.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Power Engineering (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2001
  • 2001-05-03 WO PCT/US2001/014609 patent/WO2001084068A1/en not_active Application Discontinuation
  • 2001-05-03 CN CN 01808932 patent/CN1427941A/zh active Pending
  • 2001-05-03 EP EP01935101A patent/EP1281036A1/de not_active Withdrawn
  • 2001-05-03 JP JP2001581046A patent/JP2003533874A/ja not_active Withdrawn
  • 2001-06-15 TW TW90110990A patent/TW473608B/zh not_active IP Right Cessation

Non-Patent Citations (1)

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