NOTCHED FINNED HEAT SINK STRUCTURE

Abstract: A heat sink (10) comprised of a pipe (12) attached to a plurality of fins (14).

Description: Notched Finned Heat Sink Structure BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to heat sinks and methods of making the same. 2. Description of the Related Art Known finned heat sink structures include a plurality of closely disposed heat dissipating fins that are joined to a heat pipe or fluid transfer tube by use of a thermally conductive adhesive or solder. Each of the fins has a cavity about its center region dimensioned to accommodate the heat pipe or fluid transfer tube. Because of the close proximity of the fins to each other " when mated with the pipe, it is difficult to apply the adhesive or solder near the interface of the fin cavity and the heat pipe so as to efficiently assemble the finned heat sink structure. Accordingly, an improved heat sink structure is desired which allows solder to be easily applied to a heat pipe mated with a plurality of fins . SUMMARY OF THE INVENTION The present invention is directed to a heat sink structure having a heat conduit such as a pipe, connected to a plurality of fins. The fins dissipate heat into an environment containing the heat sink structure. Each fin in the plurality is constructed of a thermally conductive material having two opposing faces and an edge. The opposing faces define a cavity therein which is dimensioned for seating about the pipe exterior surface. The edge defines an opening having a sidewall extending from the edge to the cavity. Means are provided for attaching the plurality of fins to the exterior surface of the pipe. For example, solder or adhesive is applied to the pipe via access through the opening . The present invention is also directed to a method of making a heat sink structure. The inventive method includes providing a plurality of fins, with each fin being constructed of a thermally conductive material having two opposing faces and an edge. The opposing faces define a cavity therein which is partially bounded by a flange. The edge defines an opening extending from the edge to the cavity. A pipe is then disposed within the cavity of each fin so that the pipe outer surface rests on a portion of each said flange. An adhesive material is disposed on the pipe outer surface by accessing the pipe outer surface through the openings in the fins . Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 depicts a plurality of fins attached to a heat pipe in accordance with the present invention; and Fig. 2 depicts a detail of one of the fins of the device in Fig. 1. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS A heat sink structure 10 in accordance with a preferred embodiment of the present invention is depicted in Fig. 1. The heat sink structure includes a pipe 12 connected at one end to a plurality of fins 14, with the other * end of the pipe connected to a heat source 16 such as an evaporator block containing or supporting an integrated circuit, etc. The pipe 12 provides a conduit for heat exchange between the source 16 and the fins 14 to allow for heat carried by the pipe 12 to the fins to be dissipated to the environment, in a manner well known to those having ordinary skill in the art. The pipe 12 may be a solid heat pipe or a fluid transfer tube containing fluid for providing the desired heat exchange between the source 16 and the fins 14. With reference to Fig. 2, each fin 14 is preferably constructed of a thermally conductive sheet or plate material having a front face 16 and a rear face 18 and defining a cavity 20 formed therein. The cavity 20 is preferably dimensioned for seating about a diameter of the pipe 12 as discussed more fully below. Thus, for a pipe having a circular cross section of a particular diameter, the cavity 20 is dimensioned slightly larger than the pipe diameter. The cavity 20 is bounded by a sidewall or edge 22 at which a flange 24 is preferably attached for providing an interface between the pipe and the fins 14. Thus, when the pipe 12 is inserted into or otherwise disposed within the cavities 20, the flange 24 collars or substantially surrounds a circumference of the pipe, as shown in Fig. 1. The flange 24 also provides an offset or space between adjacent fins in the plurality as shown in Fig. 1. Although the flange 24 is depicted in Fig. 2 as depending from one face of the fin (e.g., face 16) it will be readily recognized that the flange may extend from either or both faces without departing from the scope of the invention. It should be appreciated that for fins 14 having specific thicknesses, the edge or sidewall 22 may provide adequate contact with the pipe surface, in which event the flange 24 may not be required. With continued reference to Fig. 2, each fin 14 has an edge 26 defining and opening 28 extending from the edge 26 to the cavity 20. The opening has a pair of walls or edges 30 which are preferably tapered inwardly toward each other (as shown) so that the opening 28 resembles a 'V-shaped notch. Alternatively, the opening may be configured as a 'U' -shape or semicircular shape so long as it provides its intended purpose of facilitating application of solder material to the pipe and fins in a manner described below. When pipe 12 is in place in the cavities 20, it must be thermally coupled and adhered to the fins 14 to provide for heat conduction. This is accomplished by applying a thermally conductive adhesive or bonding agent such as a solder material 32 for joining the pipe to the fins. Specifically, openings 28 provide access to an exposed region of the pipe surface area for disposing the solder 32 either directly thereon, or by applying solder to the opening sides 30 and heating the heat sink structure to cause the solder to flow downward along the sides 30 to the pipe 10. Thus, the opening 28 in the fin allows for ease of application of the solder to the fin and pipe interface area, i.e. to the area where the flange 24 meets the heat pipe 10. An efficient thermal contact results when the solder or bonding material 32 flows and adheres between the flange 24 and all or substantially all of the contact area between the pipe and the flange or wall 22 so that air bubbles that may be present in the contact area are removed. This is facilitated by providing an additional opening or notch 36 located at the cavity and flange interface which allows the attachment solder or epoxy to wick or flow along the surface of the pipe and along the flange so that, when cured, the solder will bond and provide thermal coupling between the pipe and fins . The application of the solder 32 can be in a preform or paste that is applied to the sidewalls 30, either before or after the pipe is disposed in the cavities 20, or may be disposed directly in the opening 28 once the pipe is in place. To assemble the components of the inventive heat sink 10, the fins 14 can be placed on the pipe 12 in any known manner. For example, they can be placed over a free end of the pipe one at a time by simply aligning and mating the pipe with the cavity of each fin. Alternatively, the fins can be pre-stacked or aligned in a support structure (not shown) whereupon the end of the pipe can be fed through the fin cavities simultaneously. In a further alternate embodiment, rather than feeding the end of the pipe through the cavities, a length of the pipe may be laid within the opening 28 and forced downward into the cavities 20 by applying a downward force in a direction of arrow X. As a result of the tapered sides 30, this will cause the sides to temporarily separate in a direction shown by arrows Y to allow passage of the pipe into the cavity, whereupon the sides will spring back to their rest position (shown in Fig. 1) . In either case, once the pipe is in place, the solder or adhesive will be cured between the fins and the pipe, such as by heating the heat sink structure to allow a preform to flow or by applying a paste or preform and then heating the structure . Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims: CLAIMS 1. A heat sink structure, comprising: a pipe having an exterior surface; a plurality of fins to dissipate heat into an environment containing the heat sink structure, each fin in the plurality being constructed of a thermally conductive material and having two opposing faces and an edge, the opposing faces defining a cavity therein dimensioned for seating about the pipe exterior surface, said edge defining an opening having a sidewall extending from the edge to the cavity; and means for attaching the plurality of fins to the exterior surface of the pipe. 2. The heat sink structure of claim 1, wherein the pipe is one of a heat pipe and a fluid transfer tube. 3. The heat sink structure of claim 1, wherein at least one fin in the plurality comprises a flange positioned about a periphery of the cavity for attaching the at least one fin to the exterior surface of the pipe. 4. The heat sink structure of claim 1, wherein the opening of each of the fins are aligned to form a single channel . 5. The heat sink structure of claim 1, wherein the opening sidewall comprises a pair of opposing sidewalls tapered inwardly from the edge to the cavity. 6. The heat sink structure of claim 3, wherein the flange has opposing edges about the opening. 7. The heat sink structure of claim 1, wherein the attaching means comprises a solder preform. 8. The heat sink structure of claim 1, wherein the attaching means comprises a solder paste. 9. The heat sink structure of claim 6, wherein said opposing edges are tapered relative to a plane containing the at least one fin. 10. A method of making a heat sink structure, comprising the steps of: providing a plurality of fins, each fin being constructed of a thermally conductive material having two opposing faces and an edge, the opposing faces defining a cavity therein which is partially bounded by a flange, the edge defining an opening extending from the edge to the cavity; disposing a pipe within the cavity of each fin so that the pipe outer surface rests on a portion of each said flange; and disposing an adhesive material on said pipe outer surface by accessing the pipe outer surface through the openings in the fins . 11. The method of claim 10, wherein the pipe is one of a heat pipe and a fluid transfer tube. 12. The method of claim 10, wherein said disposing step comprises feeding the pip through the fin cavities . 13. The method of claim 10, wherein said disposing step comprises placing the pipe of the openings of the plurality of fins and applying a force so that the pipe moves within the cavities . 14. The method of claim 10, wherein the opening comprises a 'V -shaped opening. 15. The method of claim 10, wherein said adhesive comprises a solder material.

Inventors: CHEUNG CHE M, GAILUS DAVID W, MOORE MARVIN F, CHEUNG, CHE, M., GAILUS, DAVID, W., MOORE, MARVIN, F.
Applicants: AAVID THERMALLOY LLC, AAVID THERMALLOY, LLC
Application year: 2001
Main classification: F28F1
IPC codes: B23K1, F28D15, F28F1, H01L23, H05K7