US20060032617A1

US20060032617A1 - Heat sink electronic components

Info

Publication number: US20060032617A1
Application number: US11/012,958
Authority: US
Inventors: Chun-Chi Chen; Shi-Wen Zhou; Chi Liang; Meng Fu
Original assignee: Hon Hai Precision Industry Co Ltd
Current assignee: Hon Hai Precision Industry Co Ltd
Priority date: 2004-08-14
Filing date: 2004-12-14
Publication date: 2006-02-16
Also published as: CN2727959Y

Abstract

A heat sink for electronic component includes a base, a first heat dissipation member coupled to the base, heat pipes embedded in the base and a second heat dissipation member coupled to the base. The base is made of a first metal material and includes a heat absorbing portion having a bottom surface for contacting with the electronic component and a heat conductive portion extending from a top surface of heat absorbing portion. The first heat dissipation member is made of a second metal material and coupled to the heat absorbing portion of the base. The second heat dissipation member is made of second metal material and coupled to the heat conductive portion of the base. The first metal material differs from and has higher heat conductivity than the second metal material.

Description

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention generally relates to a heat sink for cooling heat-generating components, and particularly to a heat sink for efficiently cooling electronic components.
2. Related Art
In recent electronic apparatus, integrated circuit devices, microprocessors and other related computer components are becoming more and more powerful with increasing of capabilities, which results in increasing of packaging densities and amounts of heat generated by these components. Sizes of Packaged units and integrated circuit devices are decreasing, while the amount of heat generated by these components per unit volume, mass, surface area or any other such metric is increasing. On the other hand, the heat generating components including LSI (large scale integrated circuit) are assembled in high packaging density on printed circuit boards and many these printed circuit boards are inserted into a cabinet with a small spacing. Therefore, the heat generation rate within each electronic apparatus is strikingly increased. In recent designs, the space for packaging each heat sink has become narrower, and the heat radiation within the electronic apparatus has become an extremely difficult problem.
Heat sinks are devices attached directly to electronic components or other heat sources to enhance heat dissipation thereof. A heat sink is generally designed with a base for contacting with the heat source to absorb heat therefrom, and a plurality of fins or other like element affixed on the base for dissipating heat transferred from the base. The heat sink is often designed with a greater volume, and made of a higher conductivity material for a large capability of heat dissipation.
A conventional heat sink is made of aluminum. In order to acquire a satisfied capability of heat dissipation, a great volume of the heat sink is needed, which conflicts with the narrower and narrower usable space. As an improvement of capability of heat dissipation, copper preferred.
Another consideration when designing a heat sink is weight. Although copper-based heat sinks may be preferred over aluminum due to better heat transfer results, copper is a heavier material. A whole copper heat sink will show a passive deflect on a printed circuit board (PCB). The deflection of the PCB can cause component damage as well as damage to the PCB traces and solder pads.
In order to dissipate continuously and effectively the heat generated by the electronic apparatus, various designs bring out. A typical heat sink is disclosed in Taiwan patent publication No. 326939. The heat sink comprises a T-shaped base made of a single material and a heat dissipation member coupled with the base. The heat generated by a heat source is absorbed by the base and then transferred to the heat dissipation member and emitted to ambient air. The above-mentioned problems exist in the same way. There is not an all-sided settlement whether the heat sink is made of single aluminum or single cooper. An improvement is needed.
Along with increasing of the heat generated, phase change type products with great high heat conductivity, such as heat pipes, have been widely applied to heat sinks for enhancing the performance thereof. Heat pipes are hermetically sealed chambers, inside of which has a wicking structure and fills with working fluid. According to the principles of phase change heat transfer, thermal energy enters an evaporative section of the heat pipe and vaporizes the working fluid. The fluid moves through the heat pipe to an area of lower temperature, and then condenses. After the vapor condenses, the wicking structure draws the liquid back to the evaporative section by capillary action within the wick. The cycle is repeated continuously. Because of the rapid transport capability of the vapor, heat pipes have a very high effective thermal conductivity over large distances.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a heat sink for an electronic component, with an excellent heat dissipating performance and a smaller weightiness and volume.
It is accordingly another object of the present invention to provide a heat sink incorporating heat pipes for heat dissipation efficiency of the heat sink.
To achieve the above-mentioned objects, a heat sink is applied. The heat sink comprises a base including a heat absorbing portion having a bottom surface contacting with the electronic component and a heat conductive portion extending from the surface opposite to the bottom surface of heat absorbing portion. A first heat dissipation member is coupled to the conductive portion of the base.
As a specified embodiment, the base is made of a first metal material, and the first heat dissipation member is made of a second metal material. The first metal material differs from and has a higher conductivity than the second metal material. Further, the first metal material is copper and the second material is aluminum.
And as another specified embodiment, at least a heat pipe is embedded into the base and thermal couples the heat absorbing portion to the heat conductive portion. At this circumstance, it is not limited to that the second metal material differs from the first metal material. The base with heat pipe embedded therein has similarly higher equivalent heat conductivity than the first heat dissipation made of single metal.
The foregoing and other objects and features of the invention will become apparent from the following description of preferred embodiments of the invention with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the heat sink as a preferred embodiment of the present invention;
FIG. 2 is an exploded perspective view illustrating the base and the first heat dissipation member in FIG. 1; and
FIG. 3 is a fully assembled view of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In the following detailed description of the embodiments, reference is made to the accompanying drawings that illustrate embodiment of the present invention and its practice. FIG. 1 is an exploded perspective view of a heat dissipation assembly like a heat sink 1 for a heat generating member like an electronic component (not shown) in accordance with the present invention. The heat sink 1 comprises an inverted T-shaped base 10, a first heat dissipation member 20, several heat pipes 30, a second heat dissipation member 40 and a cover body 50.
Referring to FIG. 2, the base 10 is made of a first metal material with a first conductivity, copper being preferred, and comprises a horizontal flat heat absorbing portion 12 which has a bottom surface for contacting with the electronic component and a top surface opposite to the bottom surface, and a heat conductive portion 14 extending upwardly and perpendicularly from the middle of the top surface of the heat absorbing portion 12. The heat conductive portion 14 has two opposite side surfaces. Two pairs of grooves 16 are defined in the top surface of the heat absorbing potion 12 and extend to side faces of the heat conductive portion 14 to therefore become form of erect “L”. That is, each groove 16 comprises a level portion 16A extending on the top surface of the heat absorbing portion 12 and an erect portion 16B extending on one side surface of the heat conductive portion 14. To optimize the effect of heat transfer and meet the requirement of fabrication, the two pairs of grooves are arrayed in a stagger manner on opposite side surfaces of the heat conductive portion 14 and the top surface of the heat absorbing portion 12.
Referring to FIG. 1 again, each heat pipe 30 has an L shape and comprises a horizontal evaporative section 32 and a condensative section 34 extending perpendicularly from one end of the evaporative section 32. Each heat pipe 30 is so fitted into a corresponding groove 16 that the evaporative section 32 is disposed in the level portion 16A of the groove 16 and the condensative section 34 is disposed in the erect portion 16B of the groove 16.
The first heat dissipation member 20 is a flat metal plate defining an opening 22 therein. The heat absorbing portion 12 of the base 10 is fittingly received in the opening 22 of the first heat dissipation member 20 to thereby combine the base 10 with the first dissipation member 20. The first heat dissipation member 20 extends in a plane parallel to the bottom face of the base 10. It is preferable that the bottom face of the first heat dissipation member 20 is coplanar with the bottom face of the base 10. A plurality of fins 24 is formed on the top surface of the first heat dissipation member 20 by and not limited to extrusion or soldering. A significant characteristic of the first heat dissipation member 20 is that it is made of a second metal material differing from the first metal material, aluminum being referred, with a second heat conductivity lower than the first conductivity. Generally, the second metal material is lighter than the first metal material.
The second heat dissipation member 40 comprises a group of fins 42, generally made of aluminum, parallel to each other. Pluralities of passages are formed between adjacent fins 42 and the heat conductive portion 14 of the base 10. The second heat dissipation member 40 is attached to the heat conductive portion 14 in a arrangement that the fins 42 are attached perpendicularly to the side face of the heat conductive portion 14 of the base 10, and thermally contact with the condensative sections 34 of the heat pipes 30, by means of soldering, paste or the like.
Please refer to FIG. 3 together with FIG. 1, the cover body 50 has an inverted U shape and is fixed to the first heat dissipation member 20 by screws. The cover body 50 covers the second heat dissipation member 40 so as to construct the passages between the fins 42 into ducts with two open ends. When a fan (not shown) is mounted to one side of the second heat dissipation member 40 and orthogonal to the fins 42, the air flow provided by the fan travels through the ducts so as to carry the heat accumulated at the fins 42 out.
In the above description of the embodiments of the present invention, the connection between the base 10 and the first heat dissipation member 20, between the heat pipes 30 and the base 10, and between the base 10 and the second heat dissipation member 40 can be accomplished in any known ways familiar to those of ordinary skill in the art, such as highly thermally conductive epoxy, soldering or only mechanical engagement.
It is obvious that the heat pipes 30 are not necessary for the heat sink 1 under a condition that the first metal material differs from and has a higher conductivity than the second metal material. In the same way, it is not necessary that the first metal material differs from and has a higher conductivity than the second metal material when the heat pipes are applied. It is optimal that both of those are provided. Due to significantly high heat conductivity of the base with embedded heat pipe, the heat absorbed by the heat absorbing portion 12 is quickly transferred to the heat conductive portion 14 and there is a slight temperature difference between the heat absorbing portion 12 and the heat conductive portion 14. As a result, the heat absorbing portion 12 and the heat conductive portion 14 has a nearly uniform temperature distribution, which avails to improve efficiency of heat dissipation of the heat sink 1.
The heat sink 1 has not a great volume and weight due to use of two different metal material with different heat conductivity and density. At the same time, the heat sink 1 minimizes its volume and weight and increases heat dissipation performance. This effect is further strengthened by the use of heat pipes 30.
It is recognized that the invention may be susceptible to various other modifications and alternative constructions in view of this disclosure. Although the invention has been shown and described in detail herein by a preferred embodiment and certain alternatives, it should be understood that there is no intention of limiting the invention strictly to this. But rather it is the intention to cover all such other modifications and alternative constructions falling within the spirit and scope of the invention as defined in the appended claims.

Claims

1. A heat sink for an electronic component comprising:

a base made of a first metal material and including a heat absorbing portion which has a bottom surface for contacting with the electronic component and a heat conductive portion extending from a top surface of the heat absorbing portion;

a first heat dissipation member thermally coupled to the heat absorbing portion of the base and made of a second metal material; and

a second heat dissipation member thermally coupled to the heat conductive portion of the base;

wherein the first metal material differs from the second metal and has a higher heat conductivity than the second metal material.

2. The heat sink as claimed in claim 1, wherein the first metal material is copper, and the second metal material is aluminum.

3. The heat sink as claimed in claim 1, wherein the heat conductive portion is perpendicular to the heat absorbing portion.

4. The heat sink as claimed in claim 1, further comprising at least a heat pipe thermally coupling the heat absorbing portion to the heat conductive portion.

5. The heat sink as claimed in claim 4, wherein the second heat dissipation member comprises a plurality of fins perpendicular to the heat conductive portion.

6. The heat sink as claimed in claim 1, wherein a plurality of fins for increasing heat dissipation surface is formed on the first heat dissipation member.

7. The heat sink as claimed in claim 1, further comprising a cover body covering the second heat dissipation member.

8. A heat sink for a heat generating member comprising:

a base comprising a heat absorbing portion having a bottom surface for contacting with the heat generating member and a heat conductive portion extending from the heat absorbing portion away from the heat generating member;

a first heat dissipation member attached to the heat absorbing portion and stretching in a plane parallel to the bottom surface of the heat absorbing portion;

at least one heat pipe embedded in the base for transferring heat from the heat absorbing portion to the heat conductive portion; and

a second heat dissipating member comprising a plurality of fins each contacting with the heat conductive portion.

9. The heat sink as claimed in claim 8, wherein the base is made of a first metal material with a first heat conductivity, and the first heat dissipation member is made of a second metal material with a second heat conductivity higher than the first metal material.

10. The heat sink as claimed in claim 9, wherein the first metal material is copper, and the second metal material is aluminum.

11. The heat sink as claimed in claim 8, wherein the base has an inverted-T structure that comprises a horizontal heat absorbing portion and an erect heat conductive portion.

12. The heat sink as claimed in claim 11, wherein the base defined at least a groove extending from the heat absorbing portion to the heat conductive portion for receiving said heat pipes.

13. The heat sink as claimed in claim 8, wherein a plurality of fins is formed on the first heat dissipation member.

14. The heat sink as claimed in claim 8, further comprising a cover body covering the second heat dissipation member.

15. The heat sink as claimed in claim 8, wherein each fin of the second heat dissipation contacts with said heat pipe.

16. A heat dissipation assembly for a heat generating member comprising:

a base disposed next to said heat generating member and having a heat absorbing portion to thermally contact with said heat generating member;

a first heat dissipation member thermally contacting with said heat absorbing portion of said base and defining a first heat dissipation area extending from said heat absorbing portion of said base; and

a second heat dissipation member thermally contacting with a portion of said base other than said heat absorbing portion and defining a second heat dissipation area extending from said portion of said base and independent from said first heat dissipation area.

17. The heat dissipation assembly as claimed in claim 16, wherein said base is made by material different from at least one of said first and second heat dissipation member.

18. The heat dissipation assembly as claimed in claim 16, wherein said heat absorbing portion defines a surface to contact with said heat generating member and said first dissipation area of said first dissipation member is disposed by surrounding said surface.

19. The heat dissipation assembly as claimed in claim 16, wherein said portion of said base extends vertically from said heat absorbing portion away from said heat generating member and said second dissipation area of said second dissipation member is disposed by surrounding said portion.

20. The heat dissipation assembly as claimed in claim 16, further comprising a heat pipe attached to said base and extending from said heat absorbing portion to said portion of said base, said heat pipe having thermal contact with said base and at least one of said first and second heat dissipation member.