JP2003179189A - Thin heat sink and its packaging structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin heat sink, and its packaging structure, suitable for cooling heat generating bodies, e.g. electronic components or optical components, mounted with high density. <P>SOLUTION: The thin heat sink is provided with low profile porous fins 2 on a base board 3 or a flat heat pipe. Since the porous fin 2 has a large surface area, good heat dissipation performance or heat absorption performance is exhibited even if the profile is lowered. Since the porous fin 2 is lightweight, exterior plate of the flat heat pipe is not deformed by its weight during use. The inventive heat sink exhibits excellent cooling characteristics through good heat dissipation of the porous fins 2 when the base board 3 or the flat heat pipe is used in contact with a heat generating body or in the vicinity thereof, and through good heat absorption of the porous fins 2 when the porous fins 2 are used in contact with the heat generating body or in the vicinity thereof. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component (CPU, semiconductor chip, etc.) and an optical component (LD) mounted in high density.
The present invention relates to a thin heat sink suitable for cooling a heating element such as), and a mounting structure thereof.

[0002]

2. Description of the Related Art In a heat sink for cooling a heating element such as a high-density mounted electronic component or optical component, a base plate 3 as shown in FIG. A fin 20 is provided, a round heat pipe 9 is joined to the base plate 3 as shown in FIG. 10B, and a plate heat pipe 11 having a height as shown in FIG. For example, the one provided with a low non-hole fin 20 is used. In FIG. 10B, reference numeral 21 is a fitting for the round heat pipe 9.

[0003]

Problems to be Solved by the Invention FIG.
The conventional heat sink shown in (c) has a problem that the cooling characteristics are poor because the height of the holeless fin 20 is low. Further, in the heat sink shown in FIG. 10C, since the outer plate 12 of the plate heat pipe 11 is thin, the non-hole fin 20
There is also a problem in that the cooling characteristic is deteriorated due to deformation due to the weight of. It is an object of the present invention to provide a thin heat sink and a mounting structure for the thin heat sink that can stably obtain excellent cooling characteristics.

[0004]

The invention according to claim 1 is
A thin heat sink characterized in that a perforated fin having a low height is provided on a base plate.

The invention according to claim 2 is the thin heat sink according to claim 1, characterized in that a heat pipe is embedded in the base plate.

The invention according to claim 3 is characterized in that the perforated fins having a low height are constituted by a multi-hole metal plate or a wire mesh in which a large number of fine holes are formed.
Alternatively, it is the thin heat sink described in 2.

The invention according to claim 4 is the thin heat sink according to any one of claims 1 to 3, wherein the perforated fins are corrugated or plate-shaped.

The invention according to claim 5 is the thin heat sink according to any one of claims 1 to 4, characterized in that the perforated fins are provided on the base plate by metal bonding.

The invention according to claim 6 is the thin heat sink according to any one of claims 1 to 4, wherein the perforated fins are provided on the base plate by caulking.

A seventh aspect of the present invention is a thin heat sink characterized in that the base plate or the perforated fins constituting the thin heat sink according to any one of the first to sixth aspects is in contact with or close to a heating element. It is a mounting structure of.

The invention according to claim 8 is the thin heat sink according to any one of claims 1, 3 to 5, characterized in that a plate heat pipe is used in place of the base plate.

According to a ninth aspect of the present invention, there is provided a thin heat sink mounting structure in which a plate heat pipe or a perforated fin constituting the thin heat sink according to the eighth aspect is in contact with or close to a heating element. is there.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A heat sink according to claims 1 to 6 is one in which a perforated fin is provided on a base plate,
Since the perforated fin has a large surface area and good ventilation, it is excellent in heat dissipation, and even if its height is lowered, good cooling characteristics can be obtained, so that it can be used for cooling electronic components and optical components that are mounted at high density. Suitable. The heat sink of the invention according to claim 8 is one in which a perforated fin is provided on a plate-shaped heat pipe, and the perforated fin has a large surface area and is excellent in heat dissipation, and the plate-shaped heat pipe has a high cooling ability. Even if the height of the fin is reduced, sufficiently good cooling characteristics can be stably obtained. Furthermore, since the perforated fin is lightweight, the outer plate of the plate heat pipe is not deformed.

The heat sink of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a first embodiment of the heat sink of the present invention. In this heat sink, an aluminum alloy thin plate having a large number of fine holes 1 is cut into a predetermined plate shape to form a plate-shaped perforated fin 2, and one end of the perforated fin 2 is formed into a plurality of grooves 4 formed in the base plate 3. The solder 5 is joined one by one. In this heat sink, since the plate-shaped perforated fins 2 have a large number of fine holes 1 and a large surface area, good heat dissipation can be obtained even if the height thereof is lowered.

FIG. 2 is a cross sectional view showing a second embodiment of the heat sink of the present invention. This heat sink is one in which one end of the plate-shaped perforated fin 2 is held in a plurality of grooves 4 formed in the base plate 3 one by one and metal-bonded, and the same cooling characteristics as the heat sink shown in FIG. 1 can be obtained. This product has excellent workability in assembly because it does not require troublesome soldering. In FIG. 2, 6 is a notch formed by driving a chisel between the grooves 4 for crimping. Depending on the situation, in this heat sink, there is also a method of interposing a heat conductive grease or the like between the groove 4 and the plate-shaped perforated fin 2 to reduce the thermal resistance between them.

FIG. 3 is a cross sectional view showing a third embodiment of the heat sink of the present invention. This heat sink has a plurality of grooves 4 in which one end side of a serrated fin 7 is opened in the base plate 3.
It is the one that is inserted into the inside and that the wedge 8 is driven into it and caulked and joined. When the fins have the same height, this heat sink has a longer fin length than the heat sink shown in FIG.

FIG. 4 is a cross sectional view showing a fourth embodiment of the heat sink of the present invention. This heat sink is
The corrugated perforated fins 10 are soldered on the base plate 3 of the heat sink shown in FIG. 1, a hole 17 having a circular cross section is opened in the base plate 3, and the round heat pipe 9 is inserted into the hole 17. This heat sink has the same size as that of the heat sink shown in FIG. 1 and provides higher cooling characteristics. This heat sink is used for a heating element having a high heat generation density and cooling in the top heat mode.
It is desirable to interpose a heat transfer grease between the hole 17 and the round heat pipe 9 or to expand the diameter of the round heat pipe 9 after insertion to reduce the thermal resistance between them.

FIG. 5A shows a fifth heat sink of the present invention.
Is a perspective view showing the embodiment of FIG. In this heat sink, a metal net 14 formed by knitting thin metal wires 13 is formed into a corrugated shape to form a corrugated perforated fin 15 having a low height.
The outer plate 12 is soldered with 5 and the plate-type heat pipe 11 has a high cooling capacity, so that the cooling characteristics are extremely excellent. Furthermore, since the perforated fin 15 is lightweight, the weight of the perforated fin 15 does not deform the exterior plate 12 of the plate heat pipe 11.

In the present invention, the base plate 2 or the exterior plate 12 of the plate heat pipe 11 is provided with C1020, C110.
0, C1200 and other copper-based materials, A1010, A110
Aluminum materials such as 0, A5000 series, A6000 series, and A7000 series are suitable. The base plate 2 is manufactured by an ordinary method such as extrusion, forging, rolling, casting, crimping after pressing, and machining. The plate-type heat pipe 11 is manufactured by a method of joining and forming plate materials by welding, soldering, adhesive bonding, or the like, a method of utilizing mold material extrusion, or the like.

In the present invention, the perforated fins are corrugated, plate-shaped, lattice-shaped, comb-shaped, offset-shaped, such as a multi-hole metal plate in which a large number of fine holes are formed in a thin metal plate or a metal mesh woven with fine metal wires. It is formed by molding into a pin shape.
The size and the hole density (mesh) of the fine holes formed in the thin metal plate are selected so that the surface area is larger than that of the thin metal plate before the fine holes are formed.

The comb-shaped and pin-shaped perforated fins have a large thickness due to the manufacturing method, but the thickness of the entire heat sink can be suppressed by using a thin base plate or plate-type heat pipe. it can.

In the present invention, for the multi-hole metal plate or wire net constituting the perforated fin, any heat conductive material such as carbon material, ceramic material, etc. is used in addition to the copper material or aluminum material. .

The multi-hole metal plate 16 is shown in FIGS.
Various hole shapes as shown in (f) can be used.
These multi-hole metal plates 16 are manufactured by pressing a thin metal plate. As the wire net, various knitting methods as shown in FIGS. The surface area of the wire mesh can be changed by the wire diameter of the thin metal wire, the weaving method, and the like. In the present invention, the height h of the perforated fin (see FIG. 1) is preferably about 10 mm or less.

In the corrugated perforated fin shown in FIG.
The perforated fin 10 shown in (a) having a uniform height, as shown in FIG.
As the perforated fin 10 shown in (B), the height of the perforated fin 10 is not uniform, and the perforated fin 10 shown in FIG. A plurality of the perforated fins 10 may be used in a stacked manner, and when a base plate is used, the non-perforated fins 20 may be used in a stacked manner as shown in FIG. 8D.

For joining the perforated fins to the base plate or the plate-type heat pipe, it is desirable to use metal joints having good heat conduction. For metal joining, brazing (hard brazing, soft brazing) method, ultrasonic welding method,
Resistance heating welding method, arc (TIG, MIG, plasma)
Welding method and the like can be mentioned. An adhesive having good thermal conductivity may be used. When joining to the base plate, the caulking method can also be applied.

The perforated fins may be subjected to a surface treatment such as plating to improve their appearance and brazability. When the material of the perforated fin is copper, nickel plating is useful, and when it is aluminum, alumite treatment or Ni plating is useful.

Next, the mounting structure of the thin heat sink of the present invention will be described with reference to the drawings. The mounting structure shown in FIG. 9A is a CPU (heating element) mounted on the printed circuit board 18.
This is an example in which the plate heat pipe 11 is brought into contact with 19 and cooled by heat conduction. CPU 19 and plate type heat pipe 11
It is desirable to interpose a heat-conducting grease, a heat-conducting sheet, a heat-conducting curing agent or the like between them, because the thermal resistance is reduced.

The mounting structure shown in FIG. 9B is an example in which the perforated fin 10 is brought close to the CPU 19 to absorb the radiant heat, and the radiant heat is transmitted to the plate type heat pipe 11 to radiate the heat. If the perforated fins 10 are also provided on the back surface of the plate heat pipe 11, the cooling characteristics are further improved. For positioning the mesh fins and the heating element, it is effective to provide a frame on the outside of the heat sink. Even if the plate heat pipe 11 is replaced with a base plate, a similar mounting structure can be obtained.

[0029]

EXAMPLES The present invention will be described in detail below with reference to examples. (Example 1) A thin metal plate having a thickness of 0.2 mm was formed as shown in FIG.
Holes (0.23 mmφ) of the pattern shown in Fig. 3 were punched at a density of 30 mesh by pressing, and the height was 4.1 m.
A corrugated fin having a pitch of 1.4 mm was processed to form a perforated fin, and the corrugated perforated fin was caulked or soldered to a base plate to manufacture a thin heat sink. Next, the heat transfer amount was measured by bringing the base plate of this thin heat sink into contact with the heating element or bringing the perforated fins close to the heating element. The heat transfer amount means the reciprocal of the thermal resistance. C1 for the metal thin plate (perforated fin) and the base plate
A 020 copper alloy or an A1100 aluminum alloy was used.

(Embodiment 2) The same as Embodiment 1 except that a perforated fin is formed by using a wire net in which a copper wire or an aluminum wire having a wire diameter of 0.2 mm is knitted by the weaving method shown in FIG. A thin heat sink was manufactured by the same method, and the heat transfer amount was measured.

COMPARATIVE EXAMPLE 1 A thin metal plate having a thickness of 0.2 mm and a corrugated fin having a height of 4.1 mm and a pitch of 1.4 mm were used. A heat sink was manufactured and the amount of heat transfer was measured.
The heat transfer amounts measured in Examples 1 and 2 and Comparative Example 1 are shown in Table 1 as relative values.

[0032]

[Table 1]

As is clear from Table 1, Examples 1 and 2
In each of (Nos. 1 to 6), the fins were perforated and excellent in heat dissipation, and thus showed a high heat transfer amount. On the other hand, Comparative Example 1
In each of (Nos. 7 to 9), the fins had no holes, the heat dissipation was poor, and the heat transfer amount was reduced.

Example 3 A thin heat sink was manufactured by the same method as in Example 1 except that a plate heat pipe was used instead of the base plate, and the amount of heat transfer was measured.

Example 4 A thin heat sink was manufactured by the same method as in Example 2 except that a plate heat pipe was used instead of the base plate, and the amount of heat transfer was measured.

Comparative Example 2 A thin heat sink was manufactured by the same method as in Comparative Example 1 except that a plate heat pipe was used instead of the base plate, and the amount of heat transfer was measured. Example 3,
The heat transfer amounts measured in Comparative Example 4 and Comparative Example 2 are shown in Table 2 as relative values.

[0037]

[Table 2]

As is clear from Table 2, Examples 3, 4
(Nos. 11 to 14) all had a large amount of heat transfer because the fins had holes and were excellent in heat dissipation. Moreover, since the fins of the plate heat pipe were lightweight, the outer plate did not deform and functioned stably. On the other hand, Comparative Example 2 (No.
In all of Nos. 17 to 19), the fins had no holes and the heat dissipation was inferior, and moreover, the plate heat pipe was deformed and the heat transfer amount decreased.

Although the case where the corrugated perforated fins are used has been described above, the same effect as in Examples 1 to 4 can be obtained even when the perforated fins having other shapes such as a plate are used. It was confirmed by a separate experiment.

[0040]

The heat sink of the present invention has a perforated fin provided on a base plate or a plate heat pipe.
Since this perforated fin has a large surface area, it exhibits good heat dissipation or heat absorption even if the height is reduced. Moreover, since the perforated fin is lightweight, the outer plate of the plate heat pipe is not deformed by its weight. Furthermore, the heat sink of the present invention is
When the base plate or plate-type heat pipe is used in contact with or close to the heating element, it has good heat dissipation property of the perforated fins, and when the perforated fin is used in contact with or close to the heating element. Due to the good heat absorption of the hole fins,
In any case, excellent cooling characteristics can be obtained. Therefore, the heat sink of the present invention can be made thin, and is suitable for cooling electronic components, optical components, and the like mounted in high density, and has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a first embodiment of a heat sink of the present invention.

FIG. 2 is a cross-sectional explanatory view showing a second embodiment of the heat sink of the present invention.

FIG. 3 is a cross-sectional explanatory view showing a third embodiment of the heat sink of the present invention.

FIG. 4 is a transverse cross sectional explanatory view showing a fourth embodiment of the heat sink of the present invention.

5A is a perspective view showing a fifth embodiment of the heat sink of the present invention, and FIG. 5B is a sectional view taken along line aa of FIG.

6A to 6D are cross-sectional explanatory views showing an example of a perforated fin used in the present invention.

7A is a plan view and a cross-sectional view showing an example of a multi-hole metal plate used in the present invention, and FIGS. 7B to 7F are plan views.

8A to 8D are a plan view and a cross-sectional view showing an example of a wire mesh used in the present invention.

9A and 9B are cross-sectional explanatory views showing an example of the mounting structure of the heat sink of the present invention.

10A to 10C are cross-sectional explanatory views of a conventional heat sink.

[Explanation of symbols]

1 Fine hole 2 Plate-shaped perforated fins 3 base plate 4 Grooves on the base plate 5 solder 6 notches 7 Serrated fins with holes 8 wedges 9 Round heat pipe 10 Corrugated perforated fin made of multi-hole metal plate 11 Plate heat pipe 12 Exterior plate 13 thin metal wires 14 wire mesh 15 Corrugated perforated fins made of wire mesh 16 Multi-hole metal plate 17 Hole with circular cross section 18 Printed circuit board 19 CPU (heating element) 20 Corrugated non-hole fins 21 Round heat pipe fittings

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Claims (9)

[Claims] 1. A thin heat sink characterized in that a perforated fin having a low height is provided on a base plate. 2. The thin heat sink according to claim 1, wherein a heat pipe is embedded in the base plate. 3. The thin heat sink according to claim 1, wherein the perforated fin having a low height is formed of a multi-hole metal plate or a metal net having a large number of fine holes. 4. The thin heat sink according to claim 1, wherein the perforated fin has a corrugated shape or a plate shape. 5. The thin heat sink according to claim 1, wherein the perforated fins are provided on the base plate by metal bonding. 6. The thin heat sink according to claim 1, wherein the perforated fins are provided on the base plate by caulking. 7. A mounting structure for a thin heat sink, characterized in that a base plate or a perforated fin constituting the thin heat sink according to claim 1 is in contact with or close to a heating element. 8. The thin heat sink according to claim 1, wherein a plate heat pipe is used instead of the base plate. 9. A mounting structure of a thin heat sink, wherein a plate heat pipe or a perforated fin constituting the thin heat sink according to claim 8 is in contact with or close to a heating element.