JP2001234262A - Heat radiating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiating body having a small thermal expansion coefficient and excellent thermal conductivity and capable of being produced at a low cost. SOLUTION: This heat radiating body is composed of a compact 1 consisting of a mixture of Cu powder and cuprous oxide powder and incorporated with a heat pipe 3 in which a working solution to be evaporated and condensed at prescribed temperature is stored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiator, and more particularly to a heat radiator having a small coefficient of thermal expansion and excellent thermal conductivity, which can be manufactured at low cost.

[0002]

2. Description of the Related Art In a semiconductor device that generates heat, such as an arithmetic processing unit, a heat radiator is attached to the semiconductor device in order to prevent deterioration of the characteristics of the semiconductor element due to heat generation and extend the life of the semiconductor element. By radiating heat from the semiconductor device from the heat radiator, it is possible to prevent a rise in temperature in the semiconductor device and its peripheral region.

[0003] Usually, a copper radiator is used for this. Since copper has a high thermal conductivity of 393 W / (m · K), it has a property of efficiently absorbing and releasing heat, and furthermore, manufactures a radiator at low cost. In some cases, heat radiators made of copper are widely used in the field of semiconductor devices.

However, according to the conventional copper radiator, since copper has a large thermal expansion coefficient as a characteristic of copper, it has a large heat value, for example, for exchange or control of energy such as electric power having various on / off functions. It is difficult to apply it to a large-capacity semiconductor device used for a semiconductor device.

In consideration of a semiconductor device having a large calorific value, the thermal expansion coefficient of the heat radiator needs to be 15 × 10 −6 / K or less. Is as high as 17.times.10@-6 / K, which is difficult to apply to a semiconductor device having high heat dissipation. Therefore, for a semiconductor device having high heat radiation, a heat radiator composed of Mo or W having a thermal expansion coefficient similar to that of Si constituting a semiconductor element is generally used.

[0006]

However, according to the conventional radiator composed of Mo or W, it is expensive, which has a serious problem as an industrial product.

Accordingly, it is an object of the present invention to provide a radiator having a small coefficient of thermal expansion and excellent thermal conductivity, and which can be manufactured at low cost.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a molded body having a predetermined shape which is brought into contact with a semiconductor device or the like, and absorbs heat generated from the semiconductor device or the like to obtain an external device. In the heat dissipating body, the molded body is composed of a mixture of a metal such as Cu having good thermal conductivity and a powder of an inorganic compound dispersed in the metal and having a smaller coefficient of thermal expansion than the metal. It is intended to provide a radiator characterized by being performed.

Further, in order to achieve the above object, the present invention comprises a molded body having a predetermined shape which is brought into contact with a semiconductor device or the like, and absorbs heat generated from the semiconductor device or the like and emits heat to the outside. In the body, the molded body is a metal having good thermal conductivity, such as Cu, and dispersed in the metal, and a mixture of a powder of an inorganic compound having a smaller thermal expansion coefficient than the metal, A heat radiator characterized by incorporating therein a heat pipe in which a working fluid that evaporates and condenses at a predetermined temperature is accommodated in a reduced pressure state.

The powder of the above-mentioned inorganic compound may have a particle size of 200 μm or less, more preferably 60 μm or less, in order to make the dispersion state in the metal having good thermal conductivity good and uniform. preferable. Examples of the metal having good thermal conductivity include Cu, Au, Ag, and A.
It is preferable to select from l, and particularly from the viewpoint of cost, it is preferable to select Cu or Al. Powders of inorganic compounds include copper oxide, tin oxide, zinc oxide, lead oxide,
It is preferable to select from nickel oxide or aluminum oxide.

As a combination of a powder of a metal and an inorganic compound having good thermal conductivity, a combination of copper and cuprous oxide (Cu 2 O) is preferable. In this case, the mixing ratio of cuprous oxide is
It is preferable to set to 10 to 70% by volume. Oxidation 1
If the amount of copper is less than 10% by volume, the coefficient of thermal expansion of the molded body exceeds the upper limit of 15 × 10 −6 / K required for a heat-generating plate for a semiconductor device having high heat generation. Not preferred.

On the other hand, when the mixing ratio of cuprous oxide exceeds 70% by volume, good results are obtained in the coefficient of thermal expansion, but on the other hand, the thermal conductivity is lowered, and the high thermal conductivity which is a characteristic of copper is reduced. It should be avoided as it will hurt. The thermal conductivity in the present invention is often set to a high level of 50 W / (m · K) or more.

In the present invention, the molded body constituting the heat radiator is obtained by mixing the above-mentioned metal powder and inorganic compound powder,
It is preferable to manufacture this by heating it with a mold and sintering the powders integrally, whereby molded articles of various structures can be obtained. After sintering, it is possible to machine into a molded body of a predetermined structure.

In order to improve the heat radiation efficiency, it is practical to provide a radiating fin on the molded body, and in this case, the radiating fin may be formed as a part of the molded body when the molded body is molded. Alternatively, it may be formed by combining a separately prepared heat sink such as copper with a molded body.

As a method of incorporating the heat pipe into the molded product, a process is performed on the molded product to form a hole, and a heat pipe is inserted into the hole to seal the molded product. A form in which a heat pipe is fitted into the heat pipe is conceivable. In particular, the latter form is advantageous because a groove for accommodating the heat pipe can be formed at the same time when a molded article is molded. As the hydraulic fluid contained in the heat pipe,
Water, methanol, ammonia or the like is used.

[0016]

Next, an embodiment of a heat radiator according to the present invention will be described.

Examples 1 to 7 An electrolytic Cu powder having an average particle size of 37 μm and cuprous oxide having a particle size of 2 μm or less were prepared.
And then mixed for 10 hours in a dry ball mill containing steel balls.

Next, the obtained mixture is poured into a mold having a diameter of 150 mm, and the mixture is mixed with a metal having a diameter of 400 to 2 depending on the content of cuprous oxide.
After cold-pressing at a pressure of 500 kgf / cm @ 2, this was sintered in an argon atmosphere at 850 to 1000 DEG C. (temperature is changed according to the amount of cuprous oxide) .times.3 hours. A molded body was obtained.

When the structure was observed by X-ray diffraction,
The whole was homogeneous and good results were obtained. The coefficient of thermal expansion shown in Table 1 indicates that T
MA (Thermal Mechanical Ana)
lysis) apparatus, and the thermal conductivity is a result of measurement by a laser flash method.

Each of them has a coefficient of thermal expansion smaller than 15 × 10 −6 / K.
It shows excellent characteristics that greatly clear 0 W / (m · K). Therefore, if these mixtures are molded into a predetermined plate shape or the like, a high-quality heat-dissipating material having a small coefficient of thermal expansion and high thermal conductivity applicable to a high-heat-generating semiconductor device, and a low-cost heat-dissipation due to the Cu system can be obtained. Can make up the body.

[0020]

[Embodiment 8] Fig. 1 shows an example of the configuration of a heat radiator of a type in which a heat pipe is built in a molded body. 1 was obtained by using a predetermined mold from a mixture having the same composition as in Example 4 and using Examples 1 to 7
And 2 denotes a groove formed in the center of the molded body 1 during molding. 3 is a 3 W heat pipe fitted in the groove 2, and the gap with the groove 2 is
It is filled with solder 4. The heat pipe 3 is sealed by being evacuated after a predetermined amount of a working fluid such as water is injected into the heat pipe 3.

[0021]

EXAMPLE 9 FIG. 2 shows a method of manufacturing a molded body 1 having two grooves 2 using the mixture of Example 4 (the same procedure as in Examples 1 to 7; the same applies to the following examples unless otherwise described). ), 5 in groove 2
An example of a radiator in which the molded body 1 and the heat pipe 3 are integrated by fitting the W heat pipes 3 and filling the gap between the heat pipe 3 and the groove 2 with solder 4 is shown.

[0022]

Embodiment 10 FIG. 3 shows that after forming a molded body 1 using the mixture of Example 4, three holes 5 are formed in the molded body 1 and a 3 W heat pipe 3 is inserted into each of the holes 5. Then, an example of a radiator in which the molded body 1 and the heat pipe 3 are integrated by injecting the molten solder 4 from the opening end of the hole 5 and the opening end of the hole 5 is sealed with solder is shown.

[0023]

Embodiment 11 FIG. 4 shows that after using the mixture of Embodiment 4 to fabricate a molded body 1 having a radiation fin 6 on one side, three holes 5 are formed in the molded body 1 and each of the holes 5 is formed. After inserting the 5 W heat pipe 3, the molded body 1 and the heat pipe 3 are integrated by injecting the molten solder 4 from the opening end of the hole 5, and the opening end of the hole 5 is sealed with solder. Show body.

[0024]

Embodiment 12 FIG. 5 shows an electrolytic Cu having an average particle size of 50 μm.
Powder and a cuprous oxide powder having a particle size of 2 μm or less
The mixture obtained by mixing at a volume ratio of 50 and performing the same ball mill mixing as in Examples 1 to 7 was injected into a predetermined mold in which three 3 W heat pipes 3 were set, and then 500 kgf / This is an example of a radiator in which a preform is formed by cold-pressing at a pressure of cm @ 2 and then sintered in an argon gas atmosphere to form a formed body 1. In this example, a molded body in which the heat pipe 3 was not embedded was prepared, and its coefficient of thermal expansion and thermal conductivity were measured.

[0025]

EXAMPLE 13 FIG.
A molded body 1 having two grooves 2 is manufactured, a 5 W heat pipe 3 is fitted into each of the grooves 2, and a gap is formed in a solder 4.
The structure of a radiator in which a heat sink 3 made of copper is combined with the buried surface of the heat pipe 3 is shown.

According to Table 1, Examples 8 to 8 according to FIGS.
The radiator 13 does not include the heat pipe 3 and has
Thermal conductivity 149 in the heat radiator of Example 4 with the same mixing ratio of u and cuprous oxide powder (unit omitted; the same applies hereinafter)
In Example 8, Example 8 was 213 (1.43 times), Example 9 was 259 (1.74 times), and Example 10 was 276 (1.85 times).
Example 11: 301 (2.02 times), Example 12
293 (1.97 times), and Example 13 was 318
(2.13 times), they all improve the apparent thermal conductivity. The effect of improving the thermal conductivity in the present invention by incorporating the heat pipe 3 into the molded body 1 is remarkably exhibited.

[Table 1]

[0027]

As described above, according to the heat radiator of the present invention, a molded article made of a mixture of a metal such as Cu having good thermal conductivity and a powder of an inorganic compound having a small coefficient of thermal expansion, A highly useful radiator with a small coefficient of thermal expansion based on the incorporation of inorganic compound powder and excellent thermal conductivity based on a metal with good heat conductivity. Since it is possible to form the molded body with a Cu-based material, it is possible to manufacture a heat radiator suitable for a semiconductor device having high heat radiation at a low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a heat radiator according to the present invention, wherein (a) is a cross-sectional view and (b) is a plan view.

FIG. 2 is an explanatory view showing another embodiment of a heat radiator according to the present invention, wherein (a) is a cross-sectional view and (b) is a plan view.

FIG. 3 is a sectional view showing still another embodiment of a heat radiator according to the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of a heat radiator according to the present invention.

5A and 5B are explanatory views showing another embodiment of the heat radiator according to the present invention, wherein FIG. 5A is a cross-sectional view and FIG. 5B is a plan view.

FIG. 6 is a cross-sectional view showing another embodiment of a heat radiator according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded body 2 Groove 3 Heat pipe 4 Solder 5 Hole 6 Heat radiation fin 7 Heat sink

Continued on the front page (72) Inventor ▲ Winter ▼ Keihei 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Inside Hitachi Cable System Materials Research Laboratories (72) Takashi Suzumura 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Stock (72) Inventor Kazuma Kuroki 3550, Kida Yomachi, Tsuchiura, Ibaraki Pref.Hitachi Electric Wire Co., Ltd. (72) Inventor Hiroki Kitajima 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Co., Ltd. (72) Inventor Yasumu Nagai 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable, Ltd. F term in Tsuchiura factory (reference) 4K018 AA02 AA03 AA14 AB01 AC01 KA32 KA62

Claims (10)

[Claims] 1. A radiator, which is formed of a molded body having a predetermined shape and is brought into contact with a semiconductor device or the like, and absorbs heat generated from the semiconductor device or the like and discharges the heat to the outside. A heat radiator comprising a mixture of a metal such as Cu having a property and a powder of an inorganic compound dispersed in the metal and having a smaller coefficient of thermal expansion than the metal. 2. The heat radiator according to claim 1, wherein said inorganic compound powder has a particle size of 200 μm or less. 3. The method according to claim 1, wherein the metal is Cu, Au, Ag or A.
The heat radiator according to claim 1, wherein the powder of the inorganic compound is selected from the group consisting of copper oxide, tin oxide, zinc oxide, lead oxide, nickel oxide, and aluminum oxide. 4. The heat radiator according to claim 3, wherein said metal is Cu, and said inorganic compound powder is cuprous oxide powder. 5. The heat radiator according to claim 4, wherein a mixing ratio of the cuprous oxide powder in the mixture is 10 to 70% by volume. 6. The molded body according to claim 1, wherein the molded body is formed of a sintered body formed by molding a mixture of the metal powder and the inorganic compound powder and heating the mixture. The radiator described. 7. The heat radiator according to claim 1, wherein the molded body includes a heat radiating fin. 8. A radiator, which is constituted by a molded body having a predetermined shape brought into contact with a semiconductor device or the like, and absorbs heat generated from the semiconductor device or the like and discharges the heat to the outside, wherein the molded body has good heat conduction. A metal such as Cu having a property, and a mixture of inorganic compound powder dispersed in the metal and having a smaller coefficient of thermal expansion than the metal, and evaporates and condenses therein at a predetermined temperature. A heat radiator including a heat pipe containing a working fluid in a reduced pressure state. 9. The heat radiator according to claim 8, wherein said heat pipe is fitted in a groove formed in said molded body. 10. The heat radiator according to claim 8, wherein the molded body has a heat radiating fin.