Heat sink with fins over substrate

Abstract

To improve thermal performance with minimum cost increase in a device including a heat generating component and a heat sink.SOLUTION: The apparatus 1000 includes a cabinet 1002, an air mover 1006 mounted to the cabinet, a circuit board 100 mounted within the cabinet, and an air-cooled heat sink 104 mounted in thermal contact with heat-generating components on the circuit board. The heat sink includes a heat sink base 105, primary heat removal fins 106 projecting from the heat sink base in a direction away from the circuit board, and secondary heat removal fins 108 projecting from the heat sink base in a direction towards the circuit board. The air mover forces air between the primary heat removal fins and between the secondary heat removal fins.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to the electrical, electronic and computer technologies, and more particularly to a heat sink for a circuit board module. [Background technology]

[0002] A typical air-cooled circuit board has a heat-generating module mounted on the first or top surface of the circuit board, with a heat sink mounted on top of the heat-generating module. The base of the heat sink is in contact with the heat-generating module. The heat sink's fins protrude from the base away from the circuit board on the opposite side of the heat-generating module, transferring heat to the surrounding air by convection. The base extends laterally and acts as a heat spreader, thereby increasing the number of fins available to transfer heat from the heat-generating module to the air. Summary of the Invention

[0003] The principles of the present invention provide techniques for a heat sink with fins extending beyond the substrate. In one aspect, an exemplary apparatus includes a circuit board, one or more heat-generating components mounted on a surface of the circuit board, and an air-cooled heat sink mounted in thermal contact with at least one of the heat-generating components. The heat sink includes primary heat-removal fins that project away from the circuit board and secondary heat-removal fins that project toward the circuit board.

[0004] In another aspect, an air-cooled heat sink includes a base, primary heat removal fins projecting from a first major surface of the base, and secondary heat removal fins projecting from a second major surface of the base opposite the first major surface, at least a portion of the secondary heat removal fins contacting the second major surface of the base and bounding a space configured to receive a circuit board having a heat-generating component mounted thereon.

[0005] In another aspect, a method for cooling a heat-generating component mounted on a circuit board is provided. The method includes obtaining a heat sink comprising a base, a plurality of primary heat-removal fins protruding from a first surface of the base, and a plurality of secondary heat-removal fins protruding from a second surface of the base opposite the first surface. The method includes attaching the heat sink to the circuit board with the second surface of the base in thermal contact with the heat-generating component and with the plurality of secondary heat-removal fins protruding from the base beyond the circuit board, and forcing air between the fins of the heat sink by operation of an air mover (e.g., a blower or fan) during operation of the heat-generating component. Thus, during operation of the heat-generating component, the heat sink dissipates heat through the primary heat-removal fins and the secondary heat-removal fins.

[0006] Another aspect provides a cabinet, an air mover mounted to the cabinet, a circuit board mounted to the cabinet, and an air-cooled heat sink mounted in thermal contact with heat-generating components of the circuit board. The heat sink includes a heat sink base, primary heat removal fins projecting from the heat sink base in a direction away from the circuit board, and secondary heat removal fins projecting from the heat sink base in a direction toward the circuit board. The air mover is configured to force air between the primary heat removal fins and the secondary heat removal fins.

[0007] Another aspect provides a circuit board, one or more heat-generating components mounted on a surface of the circuit board, and an air-cooled heat sink mounted in thermal contact with at least one of the heat-generating components. The heat sink includes a heat sink base mounted in thermal contact with the heat-generating components and primary heat-removal fins protruding from the heat sink base in a direction away from the circuit board. The heat sink base conforms to the topology of the circuit board and the heat-generating components such that a portion of the heat sink base is closer to the circuit board and the primary fins are correspondingly longer.

[0008] In view of the above, the techniques of the present invention can provide substantial beneficial technical effects. For example, one or more embodiments may provide one or more of the following:

[0009] Improved thermal performance at minimal cost increase while adhering to form factor constraints.

[0010] Ease of assembly of a heat sink system that improves thermal performance within the constraints of the form factor compared to separate heat sinks on both sides of a circuit board.

[0011] More efficient use of space for cooling circuit boards. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of an exemplary embodiment of a heat sink having fins extending beyond a circuit board. [Figure 2] 2 is a cross-sectional view of the heat sink and circuit board shown in FIG. 1 taken along line 2-2 in FIG. 3, parallel to the length of the fins. [Figure 3] 3 is a cross-sectional view of the heat sink and circuit board shown in FIG. 1 taken along line 3-3 in FIG. 2, perpendicular to the length of the fins. [Figure 4] FIG. 10 is a perspective view of another exemplary embodiment of a heat sink having fins extending beyond the circuit board. [Figure 5] 5 is a cross-sectional view of the heat sink and circuit board shown in FIG. 4 taken along line 5-5 in FIG. 6, parallel to the length of the fins. [Figure 6] 6 is a cross-sectional view of the heat sink and circuit board shown in FIG. 4, perpendicular to the length of the fins, taken along 6-6 in FIG. 5. [Figure 7] FIG. 10 is a perspective view of another embodiment of a heat sink having fins extending through the circuit board. [Figure 8] 8 is a cross-sectional view of the heat sink and circuit board shown in FIG. 7 taken along line 8-8 in FIG. 9, parallel to the length of the fins. [Figure 9] 9 is a cross-sectional view of the heat sink and circuit board shown in FIG. 7 taken along line 9-9 in FIG. 8, perpendicular to the length of the fins. [Figure 10] FIG. 1 is a schematic diagram of a cabinet enclosing a heat sink and a circuit board according to an exemplary embodiment. [Figure 11] FIG. 10 is a perspective view of another embodiment of a heat sink having fins extending beyond the circuit board. [Figure 12] 12 is a cross-sectional view of the heat sink and circuit board shown in FIG. 11 taken along line 12-12 of FIG. 13, parallel to the length of the top fin. [Figure 13] 13 is a cross-sectional view of the heat sink and circuit board shown in FIG. 11 taken along line 13-13 of FIG. 12, parallel to the length of the lower fin. [Figure 14] FIG. 1 is a top view of a circuit board having heat pipes and cooling fins according to an exemplary embodiment. [Figure 15] FIG. 15 is a side view of the circuit board, heat pipes, and cooling fins shown in Figure 14. [Figure 16] 1 is a schematic side view of a circuit board and a heat sink according to an exemplary embodiment. [Figure 17] 1 is a schematic side view of a circuit board and a heat sink according to an exemplary embodiment. [Figure 18] 1 is a flowchart of a method for cooling a circuit board in accordance with an illustrative embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] FIGS. 1, 2, and 3 illustrate a circuit board 100 having one or more heat-generating components 102 (best seen in FIGS. 2 and 3) attached thereto. Exemplary heat-generating components include a processor, random access or read-only memory, or other computer circuitry. In one or more embodiments, the heat-generating components 102 may be attached, by way of non-limiting example, via controlled collapse chip connection (C4) technology or other types of solder connections. A heat sink 104 is mounted on top of the heat-generating components 102. The heat sink 104 includes mounting holes 103 (best seen in FIG. 1) for mounting the heat sink to the circuit board 100. A base 105 of the heat sink 104 contacts the heat-generating components 102 via any known type of thermal interface material, not shown because it cannot be illustrated. Note that the thermal interface material, while desirable, is optional in all embodiments. In one or more embodiments, the heat sink base 105 encloses a vapor chamber that transfers heat from the heat-generating component 102 to primary fins 106 protruding from the top of the heat sink base 105 opposite the heat-generating component 102 and away from the circuit board 100. Vapor chambers function according to principles known and well understood by thermal designers. In other embodiments, the heat sink base 105 is a solid block of metal or other thermally conductive material. The primary fins 106 are affixed to the base 105 and transfer heat from the base 105 to the ambient air by convection. In one or more embodiments, the primary fins 106 are formed as C-channels attached to the heat sink base, with adjacent primary fins defining open-ended passages, closed at the top, through which ambient air flows the length of the heat sink. Heat sink 104 also includes secondary fins 108 that project opposite the primary fins from base 105 toward and beyond an edge 109 (best seen in FIG. 2) of circuit board 100. Secondary fins 108 also transfer heat from base 105 to the surrounding air by convection.Because the secondary fins 108 protrude from the side of the circuit board 100 opposite the heat-generating components 102, they protrude into ambient air that may be cooler than that available on the same side as the heat-generating components 102. Additionally, the secondary fins 108 increase the number of fins available within the footprint of the heat sink 104. Thus, the secondary fins 108 improve the transfer of heat from the base 105 to the ambient air. In one or more embodiments, the circuit board 100 is oriented such that the channels formed by the primary fins 106 and secondary fins 108 extend vertically, thereby promoting natural convection of ambient air through the channels via a chimney effect. In one or more embodiments, the circuit board 100 is oriented otherwise, and an air mover (shown in FIG. 10 ) forces ambient air through the channels formed by the fins. Note that the term “air mover,” as used herein, is intended to encompass any suitable pressure-increasing air-moving device, such as, but not limited to, a blower or fan.

[0014] Figures 4, 5, and 6 show a circuit board 400 with one or more heat-generating components 402 (best seen in Figures 5 and 6) mounted thereon. A heat sink 404 is mounted on top of the heat-generating components 402. The heat sink 404 includes mounting holes 403 (best seen in Figure 4) for mounting the heat sink to the circuit board 400. A base 405 of the heat sink 404 contacts the heat-generating components 402 via a thermal interface material (not shown). Primary fins 406 protrude from the top of the heat sink base 405 away from the circuit board 400, opposite the heat-generating components 402. The primary fins 406 transfer heat from the base 405 to the ambient air by convection. The heat sink 404 also includes secondary fins 408, 411 that protrude from the base 405 toward and beyond a notched edge 409 of the circuit board 400, opposite the primary fins. The secondary fins 408, 411 also transfer heat from the base 405 to the ambient air via convection. Because the secondary fins 408, 411 protrude on the opposite side of the circuit board 400 from the heat-generating component 402, they potentially protrude into cooler ambient air than those available on the same side as the heat-generating component 402. Additionally, the secondary fins 408, 411 increase the number of fins available within the footprint of the heat sink 404. Thus, the secondary fins 408, 411 improve the transfer of heat from the base 405 to the ambient air. In one or more embodiments, the first group of secondary fins 408 has a different pitch, height, and / or thickness than the second group of secondary fins 411. Such variations are equally applicable (although not explicitly shown) to the embodiments of FIGS. 1 and 7.

[0015] 7, 8, and 9 show a circuit board 700 with one or more heat-generating components 702 (better seen in FIGS. 8 and 9) mounted thereon. A heat sink 704 is mounted on top of the heat-generating components 702. The heat sink 704 includes mounting holes 703 for mounting the heat sink to the circuit board 700. A base 705 of the heat sink 704 contacts the heat-generating components 702 via a thermal interface material (not shown). Primary fins 706 protrude from the top of the heat sink base 705 away from the circuit board 700 on the side opposite the heat-generating components 702. The primary fins 706 transfer heat from the base 705 to the ambient air by convection. The heat sink 704 also includes secondary fins 708 that protrude from the base 705 through notches 709 in the circuit board 700 on the side opposite the primary fins. The secondary fins 708 also transfer heat from the base 705 to the ambient air by convection. Because the secondary fins 708 protrude on the side of the circuit board 700 opposite the heat-generating component 702, they potentially protrude into cooler ambient air than those available on the same side as the heat-generating component 702. Additionally, the secondary fins 708 increase the number of fins available within the footprint of the heat sink 704. Thus, the secondary fins 708 improve the transfer of heat from the base 705 to the ambient air.

[0016] FIG. 10 shows a schematic diagram of an assembly 1000 that can include any of the embodiments described herein. For example, referring to the embodiment of FIGS. 1-3, the assembly 1000 includes a cabinet 1002 in which a circuit board 100 is mounted. Optionally, the circuit board 100 is mounted to a backplane 1004. An air mover (e.g., a blower or fan) 1006 forces ambient air through the channels in the heat sink 104 (between the primary fins 106 and between the secondary fins 108 around the base 105), and the air is exhausted from the cabinet 1002 through vents 1008. The air mover can be connected to the (closed) channels between the fins via appropriate ducts and an inlet plenum, and air can pass from the channels between the fins through, for example, an outlet plenum and appropriate ducts and through the vents 1008. Alternatively, open channels between the fins can be used, and the air mover can simply supply air to the cabinet interior. Additionally, an air mover can be provided at the inlet or outlet, as desired.

[0017] 11, 12, and 13 show another embodiment of a heat sink 1104 having fins 1108 extending beyond the circuit board 1100. One or more heat-generating components 1102 (better seen in FIGS. 12 and 13) are attached to the circuit board 1100. The heat sink 1104 is mounted on top of the heat-generating components 1102. The heat sink 1104 includes mounting holes 1103 for attaching the heat sink to the circuit board 1100. The base 1105 of the heat sink 1104 contacts the heat-generating components 1102 via a thermal interface material (not shown). Primary fins 1106 protrude from the top of the heat sink base 1105, away from the circuit board 1100, opposite the heat-generating components 1102. The primary fins 1106 transfer heat from the base 1105 to the ambient air via convection. The heat sink 1104 also includes secondary fins 1108 that protrude from the base 1105 through notches 1109 in the circuit board 1100 on the side opposite the primary fins. The secondary fins 1108 also transfer heat from the base 1105 to the ambient air by convection. Because the secondary fins 1108 protrude on the side opposite the heat-generating components 1102 of the circuit board 1100, they potentially protrude into cooler ambient air than that available on the same side as the heat-generating components 1102. Additionally, the secondary fins 1108 increase the number of fins available within the footprint of the heat sink 1104. Thus, the secondary fins 1108 improve the transfer of heat from the base 1105 to the ambient air.

[0018] 14 and 15 show a circuit board 1400 with a heat sink 1404 having heat pipes 1405 and cooling fins 1406, 1408 attached thereto, according to an exemplary embodiment. One or more heat-generating components 1402 are attached to the circuit board 1400. The heat sink 1404 is attached to the heat-generating components 1402. The heat sink 1404 includes heat pipes 1405 that contact the heat-generating components 1402 via a thermal interface material (not shown). Primary fins 1406 project from the heat pipes 1405 away from the circuit board 1400. The primary fins 1406 transfer heat from the heat pipes 1405 to the surrounding air by convection. The heat sink 1404 also includes secondary fins 1408 that project from the heat pipes 1405 through notches 1409 in the circuit board 1400 on the opposite side of the primary fins. The secondary fins 1408 also transfer heat from the heat pipes 1405 to the ambient air via convection. Because the secondary fins 1408 protrude from the opposite side of the circuit board 1400 from the heat-generating components 1402, they potentially protrude into cooler ambient air than those available on the same side as the heat-generating components 1402. Additionally, the secondary fins 1408 increase the number of fins available within the footprint of the heat sink 1404. Thus, the secondary fins 1408 improve the transfer of heat from the heat pipes 1405 to the ambient air. Those skilled in the art will be familiar with the use of heat pipes as reflux boilers or with appropriate wicking structures that enable operation against gravity. Heat from the components 1402 enters the heat pipes in the evaporator region and can be removed from the heat pipes in the condenser section near the fins 1406 and 1408.

[0019] FIG. 16 shows a schematic side view of a circuit board 1600 and a heat sink 1604, according to an example embodiment. One or more heat-generating components 1602 are attached to the circuit board 1600. The heat sink 1604 is attached to the circuit board 1600 over the heat-generating components 1602. The heat sink 1604 includes a base 1605 that contacts the heat-generating components 1602 via a thermal interface material (not shown). Primary fins 1606 project from the base 1605 away from the circuit board 1600. Secondary fins 1608a, 1608b, and 1608c project from the base 1605 toward and beyond the circuit board 1600. In one or more embodiments, at least some of the secondary fins 1608a, 1608b, and 1608c have a different thickness, pitch, and / or height from one another, at least some of the primary fins 1606, or both. Similar variations in thickness, pitch, and / or height are equally applicable to the embodiments of the other figures, even if not explicitly shown. Some of the secondary fins 1608a protrude through the notch 1609 in the circuit board 1600. Other secondary fins 1608b protrude beyond the edge of the circuit board 1600. Other secondary fins 1608c protrude downward to, but not beyond, the circuit board 1600. At least some of the secondary fins 1608 protrude on the side of the circuit board 1600 opposite the heat-generating component 1602, potentially protruding into cooler ambient air than that available on the same side as the heat-generating component 1602. Additionally, the secondary fins 1608 increase the number of fins available within the footprint of the heat sink 1604. Thus, the secondary fins 1608 improve the transfer of heat from the base 1605 to the ambient air.

[0020] FIG. 17 shows a schematic side view of a circuit board 1700 and a heat sink 1704, according to an exemplary embodiment. One or more heat-generating components 1702 are attached to the circuit board 1700. The heat sink 1704 includes a base 1705 that is attached to the circuit board 1700 and contacts the heat-generating components 1702 via a thermal interface material (not shown). The base 1705 conforms to the topography of the circuit board 1700. Additionally, the base 1705 includes offset portions that protrude beyond the circuit board 1700, including a portion that protrudes through a notch 1709 in the circuit board 1700. Thus, the base 1705 supports fins of various heights, e.g., a first group of short fins 1706a, a second group of long fins 1706b, and a group of mid-height fins 1706c and 1706d. Additionally, secondary fins 1708 protrude from the underside of the base 1705 toward the circuit board 1700. If it is possible to have longer fins 1706b and mid-height fins 1706c, 1706d within the footprint of the heat sink 1704, the increased height of these fins improves heat transfer from the heat sink base 1705 to the ambient air.

[0021] In both Figures 16 and 17, "open" fins are shown that are compatible with natural (i.e., free convection) or forced air convection cooling. Similarly, "closed" channel fins can be used with forced air convection cooling.

[0022] Referring to FIG. 18 , a method 1800 for cooling a heat-generating component 102 mounted on a circuit board 100 is provided. The method includes, at 1802, obtaining a heat sink 104 including a base 105, a plurality of primary heat removal fins 106 protruding from a first surface of the base, and a plurality of secondary heat removal fins 1808 protruding from a second surface of the base opposite the first surface. Further, at 1804, attaching the heat sink 104 to the circuit board 100 with the second surface of the base 105 in thermal contact with the heat-generating component 102 and with the plurality of secondary heat removal fins 108 protruding from the base beyond the circuit board. Then, at 1806, operating an air mover (e.g., a blower or fan) forces air between the fins of the heat sink during operation of the heat-generating component. During operation of the heat-generating component, the heat sink dissipates heat through the primary and secondary heat removal fins.

[0023] Given the foregoing discussion, it will be understood that, in general terms, an exemplary device includes a circuit board 100, one or more heat-generating components 102 mounted on a surface of the circuit board, and an air-cooled heat sink 104 mounted in thermal contact with at least one of the heat-generating components, the heat sink including primary heat removal fins 106 projecting away from the circuit board and secondary heat removal fins 108 projecting toward the circuit board. In one or more embodiments, the secondary heat removal fins project beyond the circuit board. In one or more embodiments, the primary and secondary heat removal fins project from a heat sink base that surrounds a vapor chamber. In one or more embodiments, the heat sink base is configured to dissipate heat from the heat-generating components through the walls of the heat sink base to the secondary heat removal fins and through the vapor chamber to the primary heat removal fins. In one or more embodiments, the secondary heat removal fins have a different fin pitch than the primary heat removal fins. In one or more embodiments, the secondary heat removal fins extend along a different direction than the primary heat removal fins. In one or more embodiments, the secondary heat removal fins have a different height than the primary heat removal fins. In one or more embodiments, the secondary heat removal fins have a different thickness than the primary heat removal fins. In one or more embodiments, at least a portion of the secondary heat removal fins extend through a notch formed in an edge of the circuit board. In one or more embodiments, the notch is formed in a corner of the edge of the circuit board. In one or more embodiments, at least a portion of the secondary heat removal fins extend through a hole formed in the circuit board. In one or more embodiments, a heat sink includes a base to which the primary heat removal fins and the secondary heat removal fins are attached, the secondary heat removal fins including a first group of fins of a first height extending from the heat sink base toward the circuit board and a second group of fins of a second height extending from the heat sink base beyond the circuit board. In one or more embodiments, the secondary heat removal fins include a first group of fins with a first fin pitch and a second group of fins with a second fin pitch different from the first fin pitch.In one or more embodiments, the secondary heat removal fins include a first group of fins with a first fin thickness and a second group of fins with a second fin thickness different from the first fin thickness. In one or more embodiments, the primary heat removal fins and the secondary heat removal fins protrude from at least one of the heat generating components from a heat pipe that extends across the circuit board and beyond the edge of the circuit board.

[0024] According to another aspect, an air-cooled heat sink 104 comprises a base 105, primary heat removal fins 106 projecting from a first major surface of the base, and secondary heat removal fins 108 projecting from a second major surface of the base opposite the first major surface, at least a portion of the secondary heat removal fins 108 contacting the second major surface of the base and bounding a space configured to receive a circuit board 100 having a heat-generating component 102 mounted thereon.

[0025] According to another aspect, an exemplary method 1800 for cooling a heat-generating component 102 mounted on a circuit board 100 is provided, the method including, at 1802, obtaining a heat sink 104 including a base 105, a plurality of primary heat removal fins 106 protruding from a first surface of the base, and a plurality of secondary heat removal fins 1808 protruding from a second surface of the base opposite the first surface; at 1804, mounting the heat sink 104 to the circuit board 100 such that the second surface of the base 105 is in thermal contact with the heat-generating component 102 and the plurality of secondary heat removal fins 108 protrude from the base beyond the circuit board; and at 1806, forcing air between the fins of the heat sink by operation of an air mover (e.g., a blower or fan) during operation of the heat-generating component. During operation of the heat-generating component, the heat sink dissipates heat through the primary heat removal fins and the secondary heat removal fins.

[0026] According to another aspect, an exemplary apparatus includes a cabinet 1002, an air mover 1006 mounted to the cabinet, a circuit board 100 mounted to the cabinet, one or more heat-generating components 102 on the circuit board, and an air-cooled heat sink 104 mounted in thermal contact with at least one of the heat-generating components, the heat sink including a heat sink base 105, primary heat removal fins 106 projecting from the heat sink base in a direction away from the circuit board, and secondary heat removal fins 108 projecting from the heat sink base in a direction toward the circuit board, the air mover configured to force air between the primary heat removal fins and between the secondary heat removal fins. In one or more embodiments, the heat sink base includes a heat pipe 1405. In one or more embodiments, the heat sink base includes a vapor chamber.

[0027] According to another aspect, an exemplary apparatus includes a circuit board 1700, one or more heat-generating components 1702 mounted on a surface of the circuit board, and an air-cooled heat sink 1704 mounted in thermal contact with at least one of the heat-generating components. The heat sink includes a heat sink base 1705 mounted in thermal contact with the heat-generating components and primary heat removal fins 1706 protruding from the heat sink base in a direction away from the circuit board, the heat sink base conforming to the topology of the circuit board and the heat-generating components such that a portion of the heat sink base is closer to the circuit board and the primary fins are correspondingly longer. In one or more embodiments, the heat sink further includes secondary heat removal fins 1708 protruding from the heat sink base in a direction toward the circuit board. In one or more embodiments, the primary heat removal fins 1706 have a different height than the secondary heat removal fins 1708. In one or more embodiments, the primary heat removal fins have a different fin pitch than the secondary heat removal fins. In one or more embodiments, the primary heat removal fins include a first group having a first fin pitch and a second group having a second fin pitch different from the first fin pitch.

[0028] The description of various embodiments of the present invention has been presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the embodiments of the present invention. The terms used herein have been selected to best explain the principles of the embodiments, practical applications or technical improvements to technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. 1. An apparatus comprising: A circuit board; one or more heat-generating components attached to a surface of the circuit board; an air-cooled heat sink mounted in thermal contact with at least one of the one or more heat-generating components; a primary heat removal fin projecting away from the circuit board; and Secondary heat removal fins projecting toward the circuit board the heat sink comprising: An apparatus comprising:

2. The apparatus of claim 1 , wherein the secondary heat removal fins protrude beyond the circuit board.

3. The apparatus of claim 1 , wherein the primary heat removal fins and the secondary heat removal fins protrude from a heat sink base that surrounds a vapor chamber.

4. The apparatus of claim 3 , wherein the heat sink base is configured to dissipate heat from the heat-generating component through the vapor chamber to both the primary and secondary heat removal fins.

5. The apparatus of claim 1 , wherein the secondary heat removal fins have a different fin pitch than the primary heat removal fins.

6. The apparatus of claim 1 , wherein the secondary heat removal fins extend along a different direction than the primary heat removal fins.

7. The apparatus of claim 1 , wherein the secondary heat removal fins have a different height than the primary heat removal fins.

8. The apparatus of claim 1 , wherein the secondary heat removal fins have a different thickness than the primary heat removal fins.

9. The apparatus of claim 1 , wherein at least a portion of the secondary heat removal fins extend through notches formed in an edge of the circuit board.

10. The apparatus of claim 9 , wherein the notch is formed in a corner of the edge of the circuit board.

11. The apparatus of claim 1 , wherein at least a portion of the secondary heat removal fin extends through a hole formed in the circuit board.

12. 2. The apparatus of claim 1, wherein the heat sink includes a heat sink base to which the primary and secondary heat removal fins are attached, the secondary heat removal fins including a first group of fins of a first height extending from the heat sink base toward the circuit board and a second group of fins of a second height extending from the heat sink base beyond the circuit board.

13. 2. The apparatus of claim 1, wherein the secondary heat removal fins include a first group of fins at a first fin pitch and a second group of fins at a second fin pitch different from the first fin pitch.

14. 2. The apparatus of claim 1, wherein the secondary heat removal fins include a first group of fins of a first fin thickness and a second group of fins of a second fin thickness different from the first fin thickness.

15. 10. The apparatus of claim 1, further comprising a heat pipe extending from at least one of the heat-generating components across the circuit board and beyond an edge of the circuit board, the primary heat removal fins and the secondary heat removal fins protruding from the heat pipe.

16. 1. An air-cooled heat sink comprising: With the base, primary heat removal fins projecting from a first broad surface of said base; a secondary heat removal fin projecting from a second broad surface of the base opposite the first broad surface; Equipped with at least a portion of the secondary heat removal fins contact the second broad surface of the base and bound a space configured to receive a circuit board having heat-generating components mounted thereon; Air-cooled heat sink.

17. 1. A method for cooling a heat-generating component mounted on a circuit board, comprising: Obtaining a heat sink comprising a base, a plurality of primary heat removal fins projecting from a first surface of the base, and a plurality of secondary heat removal fins projecting from a second surface of the base opposite the first surface; attaching the heat sink to the circuit board with the second surface of the base in thermal contact with the heat-generating component and the plurality of secondary heat removal fins projecting from the base beyond the circuit board; forcing air between the fins of the heat sink by operating an air mover while the heat generating component is in operation; Including, During operation of the heat-generating component, the heat sink dissipates heat through the primary heat removal fins and the secondary heat removal fins. method.

18. 1. An apparatus comprising: Cabinet and an air mover attached to the cabinet; a circuit board mounted in the cabinet; one or more heat-generating components attached to the circuit board; an air-cooled heat sink mounted in thermal contact with at least one of the heat-generating components; Heat sink base, primary heat removal fins projecting from the heat sink base in a direction away from the circuit board; and a secondary heat removal fin projecting from the heat sink base in a direction toward the circuit board; the heat sink comprising: Equipped with the air mover is configured to force air between the primary heat removal fins and the secondary heat removal fins. Device.

19. 20. The apparatus of claim 18, wherein the heat sink base comprises a heat pipe.

20. 20. The apparatus of claim 18, wherein the heat sink base comprises a vapor chamber.

21. 1. An apparatus comprising: A circuit board; one or more heat-generating components attached to a surface of the circuit board; an air-cooled heat sink mounted in thermal contact with at least one of the heat-generating components; a heat sink base mounted in thermal contact with the heat-generating component; and primary heat removal fins projecting from the heat sink base in a direction away from the circuit board; the heat sink comprising: Equipped with the heat sink base conforms to the topology of the circuit board and the heat generating component such that a portion of the heat sink base is closer to the circuit board and a correspondingly longer primary fin is provided; Device.

22. 22. The apparatus of claim 21, wherein the heat sink further comprises secondary heat removal fins projecting from the heat sink base in a direction toward the circuit board.

23. 23. The apparatus of claim 22, wherein the primary heat removal fins have a different height than the secondary heat removal fins.

24. 23. The apparatus of claim 22, wherein the primary heat removal fins have a different fin pitch than the secondary heat removal fins.

25. 22. The apparatus of claim 21, wherein the primary heat removal fins include a first group having a first fin pitch and a second group having a second fin pitch different from the first fin pitch.

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