Abstract:
A heat sink for a microprocessor includes a thermally conductive base having a plurality of substantially parallel, arcuate fin structures extending outwardly in a vertical direction from the thermally conductive base. The plurality of substantially parallel fin structures have a high fin density to enhance heat dissipation from the heat sink. In one embodiment, a shroud encloses the fin structures and is attached to the thermally conductive base via latches that fit into a pair of grooves in the bottom surface of the thermally conductive base. A fan is attached to the shroud to direct a convection medium through the plurality of substantially parallel fin structures. Also described is a method of fabricating a heat sink assembly.

Description:
TECHNICAL FIELD 
     Embodiments of the present invention relate generally to a heat dissipation device for an integrated circuit assembly and, more particularly, to a structure of a heat sink. 
     BACKGROUND 
     Microprocessors and other related computer components are becoming more and more powerful with increasing capabilities, resulting in increasing amounts of heat generated from these components. Packaged units and integrated circuit die sizes of these components are decreasing or remaining the same, which increases the amount of heat energy given off by these components for a given unit of surface area. Furthermore, as computer related equipment becomes more powerful, more and more components are being placed inside the equipment which is also decreasing in size, resulting in additional heat generation in a smaller volume of space. Increased temperatures can potentially damage the components of the equipment, or reduce the lifetime of the individual components and the equipment. Therefore, large amounts of heat produced by many such integrated circuits must be dissipated, and therefore must be accounted for in designing the integrated circuit mounting and packaging devices. 
     In current packaging techniques, heat sinks are often applied to the side of microprocessors opposite the side from which the electrical pin connections are mounted to dissipate heat from the microprocessors. The overall size of the heat sinks is limited by the volume constraints of the housing. Also the current manufacturing techniques generally limit fin density to less than 2.5 fins per centimeter, and an aspect ratio of fins (fin height to fin thickness) to less than 12. To improve the amount of heat dissipated from the heat producing components, there is a need to increase a heat dissipation convection surface area of the heat sinks without increasing the volume of the heat sinks. 
     For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need to increase the heat dissipation convection surface area for a given volume of heat sink. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components. 
     FIG. 1 is a perspective view of one embodiment of the present invention showing generally the heat sink. 
     FIG. 2 is a side view of one embodiment of the present invention showing generally the thermally conductive base and the plurality of fin structure. 
     FIG. 3 is a top view of one embodiment of the present invention. 
     FIG. 4 is a front view of one embodiment of the present invention. 
     FIG. 5 is a perspective view of one embodiment of the present invention showing generally the mounting of a fan and a shroud to the heat sink. 
     FIG. 6 is a perspective view of one embodiment of the present invention showing generally the mounting of a shroud, a fan, and a microprocessor to the heat sink. 
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which embodiments of the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice such embodiments of the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of embodiments of the present invention is defined by the appended claims and their equivalents. In the drawings, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components. In the drawings, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components. 
     In this document the term “fin density” is understood as the number of fins per centimeter in a lateral direction of a heat sink having a plurality of substantially parallel fin structures. Similarly, the term “fin aspect ratio” is understood to refer to a ratio of a fin height to fin thickness. Also in this document the term “fin pitch” is understood to refer to a distance between centers of two adjacent fins. 
     This document describes, among other things, a heat sink having a high fin density (high ratio of surface area to volume), produced using a skive technology, to increase a convection surface area for a given volume of the heat sink. The skive technology consists of repeatedly shaving an extruded aluminum block to produce a plurality of substantially parallel fin structures extending outwardly from a thermally conductive base, and the plurality of fin structures having a fin density of greater than 2.5 fins per centimeter in the lateral direction to increase a convection surface area of the heat sink for a given volume of the heat sink. Unlike the conventional technology, the skive technology produces the plurality of fin structures that are integrally formed with the thermally conductive base. There are no joints or thermal interfaces between the plurality of fin structures and the thermally conductive base. The skive technique generally uses two machines to produce the plurality of fin structures having the high fin density in the heat sink. The first machine is used for clamping and guiding a long piece of extruded aluminum into a second machine. The second machine has an actuator that actuates up and down with a cutting die on a cam roller, to repeatedly shave the extruded aluminum block, to produce the plurality of fin structures having the high fin density in the heat sink. 
     FIG. 1 is a perspective view illustrating generally, by way of example, but not by way of limitation, one embodiment of a heat sink  100  according to the present disclosure. The heat sink  100  includes a plurality of substantially parallel fin structures  120  extending outwardly in a vertical direction from a thermally conductive base  110 . In one embodiment the plurality of substantially parallel fin structures  120  have a fin density of about 2.5 to 5.5 fins per centimeter in a lateral direction on the thermally conductive base. In this embodiment the plurality of substantially parallel fin structures  120  have an aspect ratio of greater than or equal to 12, a fin thickness of about 0.04 to 0.06 centimeter, and a fin pitch of about 0.19 to 0.26 centimeter. Also in this embodiment the plurality of substantially parallel fin structures have a predetermined gap  140  of about 0.14 to 0.16 centimeter between adjacent fin structures. In one embodiment the plurality of substantially parallel fin structures  120  extend outwardly having an arcuate cross-section shape in the vertical direction. In one embodiment the heat sink  100  has feet  130 A and  130 B extending outwardly and orthogonally to the lateral direction, and they are disposed across from each other on the thermally conductive base  110  of the heat sink  100 . Also in this embodiment the feet  130 A and  130 B have notches  140 A and  140 B, respectively. In one embodiment the heat sink is made of aluminum. 
     FIG. 2 is a side view illustrating generally, by way of example, but not by way of limitation, one embodiment of the plurality of substantially parallel fin structures  120  extending outwardly from a top surface  220  of the thermally conductive base  110  having an arcuate cross section shape in a vertical direction. The cross-section shape of the plurality of substantially parallel fin structures  120  can be any other shape suitable for enhancing the heat dissipation from the heat sink  100 . Also in this embodiment the plurality of substantially parallel fin structures  120  have a predetermined gap  140  between adjacent fin structures. Also shown in this embodiment is a bottom surface  210  of the thermally conductive base  110 , which is located across from the top surface  220 . 
     FIG. 3 is a top view illustrating generally, by way of example, but not by way of limitation, one embodiment of the heat sink  100  having notches  140 A and  140 B on the feet  130 A and  130 B, respectively. In this embodiment the notches  140 A and  140 B are rectangular in shape, and they are designed to receive a latch of a retention mechanism. 
     FIG. 4 is a front view illustrating generally, by way of example, but not by way of limitation, one embodiment of the heat sink  100  having grooves  410 A and  410 B on the bottom surface  210  of the thermally conductive base  110 . In this embodiment the grooves  410 A and  410 B are rectangular in shape to receive latches  540 A and  54 B (FIG.  6 ), respectively, of a shroud, and they are located near the feet  130 A and  130 B, respectively. 
     FIG. 5 is a perspective view illustrating generally, by way of example, but not by way of limitation, one embodiment of the heat sink  100  enclosed in a shroud  510  using a pair of latches  530 A and  530 B. Also shown in this embodiment is a fan  520  attached to the shroud  510  to introduce a convection medium between adjacent fin structures. 
     FIG. 6 is a perspective view illustrating generally, by way of example, but not by way of limitation, one embodiment of the heat sink  100  attached to a microprocessor  610 . In one embodiment the microprocessor is disposed opposite the side of the fan  520 . In one embodiment the microprocessor  610  is thermally coupled to a bottom surface  210  of the thermally conductive base  110 . In another embodiment a thermally conductive interface material is included between the microprocessor  610  and the bottom surface  210  of the thermally conductive base  110 . Also seen in FIG. 6 are heat sink grooves  410 A and  410 B, which receive a pair of shroud latches  540 A and a pair of shroud latches  540 B, respectively. 
     Conclusion 
     The above described heat sink provides, among other things, an enhanced heat dissipation from a microprocessor. The enhanced heat dissipation is accomplished by having a high fin density to increase a convection surface area of the heat sink for a given volume of the heat sink. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of embodiments of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.