Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
2000-07-11
2002-04-09
Cuda-Rosenbaum, I (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C165S185000, C165S080300
Reexamination Certificate
active
06367152
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a heat sink for promoting heat dissipation from a large-scaled integrated circuit or the like, and more particularly to a heat sink exhibiting enhanced cooling efficiency and a method for effectively and economically manufacturing the same.
The inventor has made research and development of a heat sink for enhancing heat dissipation of a large-scaled integrated circuit or the like and, as a result, has filed many patent applications. Heat sinks thus proposed by the inventor are each formed by subjecting, for example, an aluminum material to plastic working, to thereby raise a number of fins from a base section. A configuration of the heat sink such as a height of the radiation fins or the like which directly affects cooling performance of the heat sink permits the heat sink to exhibit novelty and originality which are never anticipated from the prior art.
Such a heat sink is mainly used as a heat dissipation element for a CPU of a personal computer or the like. In the market, a personal computer tends to be requested to exhibit a further increased processing speed, therefore, currently an increase in generation of heat from a CPU or the like due to increases in clock frequency and the number of gates is unavoidable.
In order to further enhance heat dissipation efficiency from an electronic component in view of such current circumstances, it is carried out to use a heat sink having a bottom surface area several times as large as an upper surface area of a package of a CPU or the like, which is so constructed that a metal plate made of a metal material increased in thermal conductivity as compared with a material for the heat sink is interposed between the upper surface of the package and a bottom surface of a base plate of the heat sink.
Now, such construction will be described with reference to
FIGS. 9A and 9B
by way of example. A heat sink
1
′ includes a base plate
2
′, which is fixedly mounted on a bottom surface thereof with a metal plate
6
′ having the same shape as the bottom surface of the base plate
2
′ by any suitable techniques such as brazing, screwing or the like. Then, the heat sink
1
′ is securely fixed through the metal plate
6
′ to an upper surface of a package of an electronic component E′ such as a CPU or the like while being kept in contact with the upper surface of the package.
Such construction permits heat generated from the electronic component E′ to be diffused or dispersed over a whole region of the metal plate
6
′ and then transferred to the whole bottom surface of the heat sink
1
′, resulting in heat dissipation of the heat sink
1
′ being carried out with improved efficiency.
However, the above-described screwing which takes place for fixing of the metal plate
6
′ to the bottom surface of the base plate
2
′ causes the number of parts for the fixing and the number of steps therefor to be increased, leading to an increase in manufacturing cost of the heat sink. Also, it is highly difficult to carry out the fixing while keeping the whole metal plate
6
′ in intimate or close contact with the whole bottom surface of the base plate
2
′, to thereby cause loss in heat transfer, resulting in it failing in a satisfactory improvement in performance of the heat sink.
Also, the brazing taking place for the fixing requires a pretreatment prior to the brazing. More particularly, prior to the brazing, it is required to subject a joint surface of the base plate
2
′ of the heat sink
1
′ made of an aluminum material to a surface treatment such as plating, metal spraying or the like to permit the joint surface of the heat sink to be ready for the brazing. Unfortunately, the pretreatment with respect to the heat sink
1
′ having the radiation fins
3
′ already formed thereon causes not only a manufacturing cost to be highly increased but a reduction in strength of the radiation fins
3
′ and deformation thereof due to softening of the radiation fins
3
′ by heating during the brazing.
Further, fixing of the metal plate
6
′ to the bottom surface of the base plate
2
′ is often carried out by post-attaching the metal plate
6
′ to the heat sink
1
′ after formation of the heat sink
1
′. Unfortunately, this frequently causes inadvertent bending of the radiation fins
3
′ which are inherently delicate, leading to a deterioration in yields of the heat sink.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide a heat sink which is capable of promoting heat transfer from a heat generating element to the heat sink while realizing a reduction in manufacturing cost of the heat sink and an increase in yields thereof.
It is another object of the present invention to provide a method for manufacturing a heat sink which method is capable of providing a heat sink realizing the above-described object.
In accordance with one aspect of the present invention, a heat sink is provided. The heat sink includes a base plate adaptable to be kept in direct contact with an electronic component which requires that heat be dissipated therefrom during operation thereof and radiation fins arranged so as to project from the base plate. The base plate includes a main base plate section made of a main material of which the radiation fins are made and a base plate section for promoting heat transfer (hereinafter referred to as “heat transfer promoting base plate section”) made of a heat transfer promoting material different from the material for the main base plate section. The heat transfer promoting material is previously integrated with the main material at a stage at which working of a workpiece is started.
The above-described construction of the heat sink permits heat generated from an electronic component to be diffused or dispersed over the whole heat transfer promoting base plate section and then transferred through the whole main base plate section to the radiation fins, so that the heat sink may be increased in heat dissipation efficiency.
The heat transfer promoting material is previously integrated with the main material at a stage at which working of the workpiece is started. This ensures that the heat transfer promoting base plate section is formed integrally with the main base plate section concurrently with forming of the heat sink, to thereby eliminate parts such as screws or the like for fixing of the heat transfer promoting base plate section to the main base plate section and operation for the fixing, resulting in a manufacturing cost of the heat sink being reduced and inadvertent bending of the radiation fins which are intrinsically delicate being prevented.
In accordance with this aspect of the present invention, a heat sink is provided. The heat sink includes a base plate adaptable to be kept in direct contact with an electronic component which requires that heat be dissipated therefrom during operation thereof and radiation fins arranged so as to project from the base plate. The base plate is constituted by only a heat transfer base plate section made of a heat transfer promoting material. The radiation fins are made of a main material and arranged so as to project from the heat transfer promoting base plate section. The heat transfer promoting material is previously integrated with the main material at a stage at which working of a workpiece is started. The heat sink thus constructed permits heat generated from the electronic component to be efficiently dissipated from the radiation fins.
In a preferred embodiment of the present invention, the main material is aluminum alloy and the heat transfer promoting material is a material having thermal conductivity larger than that of aluminum. Such construction promotes that heat generated from the electronic component is diffused or dispersed over the whole heat transfer promoting
Cuda-Rosenbaum I
Lerner David Littenberg Krumholz & Mentlik LLP
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