JP2807198B2 - Heat radiator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiator used to radiate heat from a component that generates heat, such as an electronic component.

[0002]

2. Description of the Related Art In recent years, ICs used in electronic devices and the like have been developed.
For electronic components such as these, the power consumption increases due to the improvement in the degree of integration and the speed of operation, and the amount of heat generation also increases.

That is, when the temperature of such an electronic component rises, the characteristics of the electronic component fluctuate, which may cause malfunction of the electronic device or cause the electronic component itself to fail. Therefore, conventionally, in an electronic device or the like, a heat sink may be used in order to suppress a temperature rise of an electronic component during use. The heat radiating plate radiates heat of the electronic component by contacting the electronic component and conducting heat generated from the electronic component to the heat radiating plate, and is made of a material having a high thermal conductivity. The heat received by the heat sink from the electronic component is radiated from the surface of the heat sink according to the temperature difference between the surface of the heat sink and the outside.

[0004]

This type of heat radiating plate can quickly conduct heat generated by an electronic component from the heated end face to the other end face. There is a limit in the ability to radiate heat to the outside of the heat sink, and there is a problem that heat is trapped in the heat sink.

If heat is trapped in the radiator plate, a sufficient radiator effect cannot be expected. Therefore, it is necessary to take measures such as increasing the surface area of the radiator plate or forcibly cooling the radiator plate. As a result, there has been a problem that it is difficult to reduce the size of an electronic device including an electronic component that requires such a heat sink.

The present invention has been made to solve the above problems.
An object of the present invention is to provide a radiator capable of efficiently radiating heat to the outside.

[0007]

According to a first aspect of the present invention, there is provided a heat radiator comprising: a sheet made of a heat radiating material having a large heat emissivity; It is characterized by being alternately laminated with sheets made of a conductive material.

[0008]

According to a second aspect of the present invention , in the heat radiator of the first aspect , the sheet made of the heat radiating material has conductivity, and the sheet is provided with a ground terminal. It is characterized by the following.

[0010] The heat radiator according to the third aspect is the first or second aspect.
In heat radiator according to claim 2, characterized in that the heat conducting material is a ferrite.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The radiator according to the first aspect of the present invention having the above-described structure is used by being attached to the upper surface of a heating element such as an electronic component. At this time, when the sheet made of the heat-radiating material receives the heat generated from the heating element directly or indirectly, the heat is promptly converted into electromagnetic waves (mainly infrared rays) and radiated to the outside.

When a sheet made of a heat conductive material directly or indirectly receives the heat generated from the heating element, the heat is quickly transmitted to the sheet .

[0013] This heat radiation member, a sheet made of a thermally conductive material on a sheet made of heat-emitting material is a laminated portion, the heat which has not been radiation is quickly conducted to the latter by the former . Conversely, where a sheet made of a heat-radiating material is laminated on a sheet made of a heat-conductive material,
The heat of the former is sequentially conducted to the latter, then converted into an electromagnetic wave and actively radiated. Therefore, these two types
Layers made of heat-radiating material
Heat that could not be radiated to the outside
Only one type of sheet for each sheet
Heat radiation is performed more efficiently than when a radiator is configured.
And the heat trapped in the radiator is reduced,
Ascent can be suppressed. In addition, compared to conventional radiators,
Since a larger heat dissipation effect can be obtained with the same volume,
Electronic devices and the like composed of electronic components using the present invention are small.
Can be typed.

By alternately performing the rapid heat conduction and the active heat radiation in this manner, heat is smoothly removed from the heating element, and the heat dissipation of the heating element can be performed efficiently. The heat radiator according to claim 2 of the present invention is, for example, affixed to an upper surface of an electronic component as a heat generator, and further includes a ground terminal provided on a conductive sheet made of a heat radiating material, The electronic component is used by being connected to the ground of the board on which the electronic component is mounted.

At this time, the electromagnetic wave generated from the electronic component is absorbed by the sheet provided with the ground terminal, since the sheet provided with the ground terminal has the conductivity, and the electromagnetic wave leaked to the outside is reduced. Therefore, according to the heat radiator, not only can the heat radiator be efficiently dissipated, but also the electromagnetic wave leaking to the outside can be attenuated.

The radiator according to the third aspect of the present invention is used, for example, by being attached to the upper surface of an electronic component as a heat generator. In the heat radiator, a sheet made of a heat conductive material is formed using ferrite, that is, an oxide compound containing iron, manganese, and cobalt as main components.

Therefore, the sheet made of the heat conductive material of the heat radiator also has the electromagnetic wave absorbing performance by ferrite. Therefore, according to this heat radiator, not only can the heat radiator be efficiently radiated, but also the electromagnetic wave can be attenuated.

The heat radiation material is a long wavelength emissivity.
Radiation with high emissivity and high emissivity in all infrared region
Body. As the former, cordierite (2MgO.2
Al _TwoO_Three・ 5SiO_Two ), Aluminum titanate (Al
_TwoO_Three・ Ti_TwoO_Three), Β-spodumene (Li_TwoO ・ A
l_TwoO_Three・ 4SiO_Two). In the latter case,
Transfer element oxide-based ceramics (for example, Mn
O_Two: 60%, Fe_TwoO_Three: 20%, CuO: 10%, C
oO: 10%), carbon black, graphite, carbon fiber, etc.
Is mentioned. Of these, carbon black and carbon fiber
4. The heat-radiating material of the heat radiator according to claim 3, which also has conductivity.
It is suitable for a sheet consisting of

The heat conductive material includes a metal or an oxide thereof, or carbon. Further, the material having each of the above properties may be a composite material mixed with a predetermined base material, and the composite material only needs to maintain the properties of the mixed materials.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Three types of heat radiators will be described below as embodiments of the present invention. Each of these heat radiators is formed by polymerizing two types of layers, a V layer and a T layer. The V layer corresponds to a sheet made of the heat-radiating material of the present invention, and has a thickness of 1 mm obtained by mixing silicone and vapor-grown carbon fiber at a weight ratio of 1: 1 to form a thin film and then vulcanizing at 180 ° C. Film. On the other hand, the T layer is equivalent to a sheet made of the heat conductive material of the present invention. Silicone and alumina are mixed at a weight ratio of 2: 1 to form a thin film, and then vulcanized at 180 ° C. to have a thickness of 1 mm. Thermal conductivity is 2.5 × 10 ^-3 [cal /
cm · ° C. · sec].

By laminating the V layer and the T layer,
The following three types of radiators were prepared. That is, the radiator 1 of the first embodiment: TV The radiator 3 of the second embodiment: V-T-V The radiator 5 of the third embodiment: TVT Here, TV is In the order of the T layer and the V layer, V-TV refers to the V layer, the T layer, and the V layer, and TVT refers to the T layer, the V layer,
This means that polymerization was performed using conductive grease in the order of the T layer. FIG. 1 shows a state in which the radiator 5 is attached to the electronic component 11. That is, FIG.
3, a T layer 5a on the upper surface of the electronic component 11 mounted on the surface of the electronic component 11.
The layers are stacked in the order of the V layer 5b and the T layer 5c and adhered.

An experiment performed to evaluate the three types of heat radiators 1, 3, and 5 will be described. As shown in FIG. 2A, the width is 12.5 mm, the depth is 20 mm, and the height is 9 mm.
A thermal conductive grease 17 is applied to the upper surface 15a of the IC 15 and a sample 19 having a width of 30 mm and a depth of 40 mm is adhered to the upper surface of the IC 15 as shown in FIG. In this state I
C15 was energized and the temperature inside IC15 was measured. For comparison, when nothing was adhered to the upper surface 15a of the IC 15 (Comparative Example 1), and the thickness of the sample 19 was 2 m.
The measurement was also performed when an aluminum plate of m m was bonded (Comparative Example 2). Note that Comparative Example 2 corresponds to the case where a conventional heat sink is used.

The results of this measurement are shown in Table 1.

[0024]

[Table 1]

From Table 1, it can be seen that the conventional radiator plate using an aluminum plate (Comparative Example 2) is 6 ° C. lower than Comparative Example 1 having no radiator plate, but the radiator 1 of the first embodiment is further reduced. The temperature is lowered by 2 ° C. to 94 ° C., which indicates that the heat radiation effect is high. Further, the heat radiator 3 of the second embodiment is 4 ° C.
The temperature is as low as 7 ° C. for the heat radiator 5 of the third embodiment. That is, ignoring the amount of heat escaping from the IC 15 to the outside air and the like other than the sample 19, the radiator 5 deprives the heat amount of the aluminum plate of the second comparative example more than twice. From the above, all of the heat radiators 1, 3, and 5
It can be seen that heat is radiated more efficiently than the conventional radiator.

Next, a description will be given of an experiment conducted to evaluate the electromagnetic wave shielding performance of the heat radiator 7 of the fourth embodiment in addition to the above three embodiments. As shown in FIG. 3, the radiator 7 is formed by laminating a T layer 5a, a V layer 5b, and a T layer 5c in this order.
The terminal 21 is attached to the. The V layer 5b
Are made of silicone and gas-phase grown carbon fiber as a heat-radiating material as described above, all of which have conductivity, and the entire V layer 5b is made of a material having conductivity.

The terminal 21 was connected to the ground of the substrate 13, and a current was applied to the IC 15 to detect a magnetic field component of an electromagnetic wave near the IC 15, and the magnetic field was measured using a near-field probe. As a result, compared to the case where the heat radiator 7 was not used,
The dB magnetic field has decreased. Therefore, according to the heat radiator 7 in which the V layer is electrically grounded, not only the heat radiation of the IC 15 can be efficiently performed but also the electromagnetic wave can be attenuated.

Next, the use of ferrite instead of a film obtained by mixing the silicone and alumina at a weight ratio of 2: 1 to form a thin film and then vulcanizing at 180 ° C. in the T layer will be described. It is well known that ferrite has an electromagnetic wave absorbing ability, but there is no example evaluated for its electrothermal performance.

FIG. 4 shows the results of an experiment comparing with the above-mentioned T layer. In this experiment, the temperature difference between the case where only the T layer was attached to the IC and the case where only ferrite was attached to the IC and the case where nothing was attached was obtained. FIG. 4 is a graph in which the vertical axis represents the ratio of this temperature difference to the temperature in the case of no attachment, and the horizontal axis represents the thickness of the attached material, that is, the thickness of the T layer or ferrite.
It is. In this graph, the same experiment was performed for an aluminum plate for reference, and plotted.

As can be seen from this graph, ferrite is
Although the thickness has to be reduced to about 1 mm, the temperature reduction performance is almost the same as that of the T layer. And, it shows superior performance as compared with the aluminum plate. That is, from this, it is understood that the same performance can be exhibited even if the T layers of the heat radiators 1 to 5 are replaced with ferrite.

Furthermore, if ferrite is used, it is possible to absorb noises and the like emitted from ICs and the like due to the well-known electromagnetic wave absorption characteristics of ferrite.
A radiator having the same features as the radiator 7 can be provided. Accordingly, if the T layer of the heat radiator 7 is made of ferrite, electromagnetic waves are absorbed in all three layers, and it is preferable to attach the heat radiator as a noise suppression measure for electronic components.

The radiator 1, the radiator 3, the radiator 5, and the radiator 7 according to the embodiments of the present invention have been described above.
The present invention is not limited to these examples, and can be implemented in various modes. For example, in the above description, a thermally conductive grease is used for laminating the T layer and the V layer, but an adhesive having particularly low thermal conductivity may be used. This is because even if the adhesive does not have good thermal conductivity, the adhesive is pressed into two layers and usually stretched thinly, so that the effect on the thermal conductivity is small. In addition, without using such a pile of adhesive,
A plurality of layers may be laminated by pressure bonding or the like.

Further, in the above, one or two T layers and one or two V layers were prepared to constitute a heat radiator. However, a layer made of a heat-radiating material different from the V layer of the present invention (referred to as a V 'layer) was used. make,
For example, the radiator may be formed by laminating in the order of VTV ′. Conversely, a layer (hereinafter, referred to as a T ′ layer) made of a heat conductive material different from the T layer is formed, and for example, a TVT ′ is formed.
May be formed in this order to form a heat radiator.

In the above description, the heat radiator is formed by laminating two or three T layers and V layers, but four or more layers may be laminated. For example, TVTV, VTVT,
It is also possible to laminate and arrange in the order of TV-T'-V, TV-TV-T. With such a multi-layer configuration, heat generated from an IC chip or the like is shared and radiated by each V layer, and heat conduction between the V layers is quickly performed by the T layer. There is no stagnation, and a higher heat radiation effect can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a usage example of a heat radiator 5 of a third embodiment.

FIG. 2 is an explanatory diagram of an experiment performed to evaluate the heat radiation performance of the heat radiators 1, 3, and 5 of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a heat radiator 7 according to a fourth embodiment of the present invention.

FIG. 4 is a graph for comparing the temperature lowering performance of a ferrite, a T layer, and an aluminum plate.

[Explanation of symbols]

 1, 3, 5, 7, radiator 5a, layer (T layer) made of heat conductive material 5b, layer (V layer) made of heat radiating material 5c, layer (T layer) made of heat conductive material 21 Terminal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-202679 (JP, A) JP-A-4-307779 (JP, A) JP-A-2-218038 (JP, A) JP-A 9-208 64253 (JP, A) Patent 2698036 (JP, B2) Patent 2638461 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23/34-23/473 H05K 7/20 F28F 13 / 18

Claims (3)

(57) [Claims] 1. A heat dissipating body characterized in that sheets made of a heat radiating material having a high heat emissivity and sheets made of a heat conductive material having a high heat conductivity are alternately laminated. 2. The heat radiator according to claim 1 , wherein the sheet made of the heat radiating material has conductivity, and the sheet is provided with a ground terminal. 3. The heat radiating member according to claim 1 or claim 2, the heat radiating body, wherein the heat conducting material is a ferrite.