JPH10247708A - Face-to-face heat conductive plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitting face-to-face heat conductive plate constituted at a super-thin shape and a super-light amount by a method wherein the plate resides between a heat radiation face of a small area of a small-sized heat generation element and a heat receiving face of heat radiating means, which are conductively connected, and a calorific value of the small-sized heat generation element is face-dispersed temperature-uniformly on the heat receiving face of the heat radiating means. SOLUTION: An extremely thin graphite sheet is set as a center layer 1, and such a thin film adhesive layer as can regard a thickness for pinching this is set as second layers 2-1, 2-2, and further a thin metal layer of high heat conductivity for pinching them is set as third layers 3-1, 3-2, and a thin film layer of a specific function which is not an essential structural element is set as fourth layers 4-1, 4-2 on an outer face of the third layers 3-1, 3-2, and then covering is performed and all of them are compression-bonded and laminated to constitute a face-to-face heat conductive plate. Thereby, the face-to-face heat conductive plate of a super-thin shape and a super-light amount having excellent heat diffusion performance and temperature uniformizing performance. The heat diffusion performance and temperature uniformizing performance are high performance which is equivalent to a plate heat pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat connecting structure for thermally connecting a heat generating element and a heat radiating means, and more particularly to a large heat quantity supplied from a small and powerful heat generating element. And a structure of an inter-surface heat transfer plate which uniformly diffuses heat to the heat radiating means to transfer heat.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have been remarkably developed, and electronic devices formed by using them have been remarkably advanced. As a result, a small, light and thin semiconductor device having a thickness of 1 mm or less and an outer dimension of 12 mm × 12 mm or less has been put to practical use as a powerful device having a heating value of 30 W.
The electronic devices on which they are mounted are correspondingly becoming smaller and smaller. There is also a demand for a small, thin, and lightweight inter-plane heat transfer plate that thermally connects the heat radiating surface of such a small heat generating element and the heat receiving surface of the heat radiating means for cooling the small heat generating element. The present inventor has proposed and commercialized a plate heat pipe disclosed in Japanese Patent Application No. 8-359631 as such an inter-surface heat transfer plate. The maximum heat transfer amount of a practically used inter-surface heat transfer plate is 40 W, and the outer dimensions are the heat radiation area of the heating element 1
3 mm x 13 mm, heat receiving area of heat radiating means 80 mm x 80
mm and a thickness of 1.5 mm. That is, the thermal diffusion magnification is 38.
It was twice.

[0003] Pure copper plates and pure aluminum plates are used as inter-surface heat transfer plates used in past or low-performance equipment. However, with such an inter-surface heat transfer plate, a high-performance small-sized device is insufficient in heat diffusion performance and further becomes excessively heavy, and a high-performance thin plate heat pipe is now used.

[0004]

During the period of practical use of the high-performance thin plate heat pipe as described above, the miniaturization and lightening of the semiconductor element in the industry have been literally continuing to evolve. At present, 80 W devices have appeared with the same external dimensions as the calorific value of semiconductor devices, and it is predicted that 120 W devices will appear in the near future.
On the other hand, in the field of small-capacity semiconductor devices of 15 W or less, more stringent conditions have started to be required for outer dimensions. The current requirements for the inter-surface heat transfer plate in the industry are those having a thickness of 1.3 mm or less, and the future goal is to provide an inter-surface heat transfer plate of 0.8 mm or less. Further, as the calorific value increases, the thermal diffusion magnification also increases. In the past, its thermal diffusivity was around 10 times, now it is around 60 times, and it is expected that it will reach 100 times in the near future.

[0005] However, the plate heat pipe has good heat diffusion performance, but the once-through heat resistance is not much different from the metal plate.
Another problem is that it is difficult to reduce the thickness to 1.5 mm or less due to its structure. Therefore, in the future 0.8 mm or less in thickness and 1
A plate heat pipe cannot technically cope with a heat transfer plate between planes corresponding to a heat diffusion magnification of 00, and some technical breakthrough is required to solve the problem. It is.

[0006]

[Means for Solving the Problems] As means for solving the problems, attention has been paid to a graphite sheet that has been developed very recently and is now available on the market. This graphite sheet containing no impurities has a thermal conductivity of 800 to 10 in the planar direction.
00 W / (m. ° C.), which is extremely high, more than twice that of a pure copper plate, and the thermal conductivity in the direction perpendicular to the plane is 5 W / (m. ° C.)
And has extremely low heat conduction performance. Its density is 1.0g
/ Cm ³ and 1 / 2.7 of aluminum, 1/8. Of pure copper.
It is characterized by its light weight of 96. 3000 more
The high heat resistance of not less than ℃ is also a major feature. Typical sheet thicknesses of commercial products are 0.1 mm and 0.2 mm. Due to the physical properties as described above, the graphite sheet has good heat diffusion performance, but the flow-through thermal resistance is large, and in order to improve it, a large pressure is required on the surface during use. Has poor adhesion to the heat receiving surface, and cannot be used as it is as an inter-surface heat transfer plate, and requires some contrivance.

FIG. 1 is a partially enlarged sectional view showing the basic structure of an inter-surface heat transfer plate 1 according to the present invention. FIG. 1 shows an inter-surface heat transfer plate 1 for uniformly dispersing the heat input from a small-area heat-receiving surface and transferring the heat to a large-area heat-dissipating surface.
An adhesive having a thickness in which thermal resistance is negligible, wherein a graphite thin sheet layer of a kind having a very high thermal conductivity in the plane direction and a very low thermal conductivity in the vertical direction penetrating the surface is used as the central layer 1-1. Second layer 2 which is a thin film layer and sandwiches central layer 1-1
-1, 2-2, and third layers 3-1 and 3-2, which are thin metal layers having high thermal conductivity and sandwich all of the central layer and the second layer. The surface of -2 is covered with fourth layers 4-1 and 4-2, which are not essential components, and are thin film layers to add special functions corresponding to the application conditions of the plate, and the central layer 1- The first and second layers 2-1 and 2-2 and the third layers 3-1 and 3-2 are characterized in that they are bonded to each other at a predetermined temperature and a high pressure and are laminated.

FIG. 2 is an explanatory view of an application state of an inter-surface heat transfer plate according to the present invention, wherein 1 is an inter-surface heat transfer plate, 5 is a small heating element, 5-1 is a heat radiating surface, and 6 is a small heating element. A heat radiation means 6-1 for radiating the heat of the element 5 is a heat receiving surface thereof.

[0009]

The operation of the inter-surface heat transfer plate according to the present invention will be described below. (1) The inter-surface heat transfer plate 1 can be used without giving a large pressing force to the heat radiating surface 5-1 of the heat generating element 5 or the heat receiving surface 6-1 of the heat radiating means 6 when transferring heat. When the graphite sheet is used as an inter-surface heat transfer plate, the adhesiveness between the heat radiating surface 5-1 of the heating element 5 and the heat receiving surface 6-1 of the heat radiating means 6 is poor, and the surface embraces air when bonding. Easily, the heat transfer performance is extremely deteriorated. Therefore, it is difficult to apply as it is,
When applying as it is, it is necessary to use it while applying a high pressing force as a measure. In many cases, this pressing force may damage the heat generating element 5 and the heat radiating means 6, and is usually unusable. This has been a major obstacle in utilizing the excellent heat diffusion performance of graphite sheets. The inter-surface heat transfer plate 1 according to the present invention includes a central layer 1-1,
Since the second layers 2-1 and 2-2 and the third layers 3-1 and 3-2 are laminated under high pressure in advance, the graphite sheet of the central layer 1-1 has already been pressurized. The entrapped air has been exhausted, and can be used as the inter-surface heat transfer plate 1 without requiring any pressing force. This is an important point of view of the present invention and a great effect.

(2) The inter-surface heat transfer plate 1 has an extremely low average density and can be made lightweight. Since the graphite sheet of the central layer 1-1 is extremely light, having a density of 1.0 g / cm ³ , the inter-surface heat transfer plate 1 having a composite structure can have an extremely low average density. For example, the central layer 1-1 may be a graphite sheet having a thickness of 0.2 mm, the third layers 3-1 and 3-2 may be thin aluminum sheets having a thickness of 0.1 mm, and the second layers 2-1 and 2-2 may be ignored. the extent of thickness of the adhesive, in the average density of the surface between the heat transfer plate 1 having a thickness of 0.4mm configured compares 1.86 g / cm ^3, and the density 2.7 g / cm ³ of Aruminiumu 33% Weight is reduced. This is an epoch-making lighter weight compared to the conventional heat transfer plate between planes (generally, pure copper plate and aluminum plate are used). It is extremely effective when used for space equipment and aviation equipment. is there.

(3) The inter-surface heat transfer plate 1 is provided with excellent heat diffusion performance by effectively utilizing the excellent planar thermal conductivity of the graphite sheet. Compensates for the drawbacks of graphite sheets, whose flow-through thermal conductivity in the direction perpendicular to the plane is only 1/80 of that of pure copper plates, thereby providing an excellent planar thermal conductivity of more than twice that of pure copper of graphite sheets. It is possible to effectively utilize the heat diffusion performance. Although the graphite sheet has an excellent thermal diffusion performance of more than twice that of pure copper, the flow-through thermal conductivity in the direction perpendicular to the plane is only 1/80 of that of pure copper. It was impossible to receive a sufficient amount of heat from the heating element, and it was impossible to utilize excellent heat diffusion performance. On the other hand, in the inter-surface heat conduction plate 1 of the present invention, the small heat radiating surface 5-1 of the small heating element 5 is formed.
Is supplied by the third layer 3-1 to expand the effective heat receiving area, and then the central layer 1
Reaches the graphite sheet, and after being sufficiently diffused by the graphite sheet, reaches the third layer 3-2 on the opposite side, and is further diffused by the third layer 3-2 to dissipate heat. Reaches the heat receiving surface 6-1. In this way, the heat transfer area of the graphite sheet is sufficiently enlarged, so that even though the through-heat conductivity of the heat in the graphite sheet is small, it receives a sufficient amount of heat and diffuses it sufficiently to diffuse the heat sufficiently, so that the heat receiving means 6 has a wide heat receiving surface. 6-1 can be effectively conducted.

(4) The inter-surface heat transfer plate 1 exhibits extremely excellent temperature uniformity on the heat radiating surface. When the plate area is extremely large, the plate heat pipe is far superior in the temperature uniformity performance. However, when the area is limited to a small area such as 100 mm × 100 mm, the inter-surface heat transfer plate 1 of the present invention is a plate heat pipe. Demonstrates uniform performance equal to heat pipes. The temperature uniformity performance is such that the heat transfer rate in the plane direction of the amount of heat in the graphite sheet is more than twice the transfer rate in the pure copper plate, and the transfer rate in the direction perpendicular to the plane in the graphite sheet is the pure copper plate. Interaction of 1/80 of the moving speed in the direction perpendicular to the plane in the inside, the high speed of the heat transfer speed of the high thermal conductivity metal of the third layers 3-1 and 3-2, and the heat transfer in the graphite. This is brought about by the mutual complementation of the high speed of the moving speed.

The temperature uniformity of the inter-surface heat transfer plate 1 is exerted by the following actions of the respective components. The amount of heat supplied from the heat radiating surface 5-1 of the small heating element 5 is diffused due to the good thermal conductivity of the third layer 3-1 and an extremely thin bond of the second layer 2-1 from the enlarged heat receiving surface. It is conducted to the graphite sheet of the central layer 1-1 via the agent layer. The graphite sheet has a flow-through thermal conductivity of 5 W / m in the direction perpendicular to the plane.
° C, which is an extremely slow heat transfer rate, whereas the planar thermal conductivity is 800 W / m ° C,
Since the heat transfer rate is twice as high, in a limited plate area such as 100 mm × 100 mm, the amount of heat introduced diffuses almost instantaneously to the entire area and raises the temperature of the entire graphite sheet. Since the thermal conductivity is extremely large, the temperature drop in the sheet is extremely small and the entire surface is almost at the same temperature. Further, if the temperature drops in a part of the sheet surface for some reason, the amount of heat stored in the sheet instantaneously replenishes the amount of heat in the temperature drop portion, so that the temperature of the sheet surface is always kept uniform. This operation is very similar to the operation in which even if a low-temperature portion is generated on the inner wall surface of the heat pipe, the temperature is instantaneously recovered by the high-speed replenishment of the working fluid vapor and the temperature is always kept uniform. Thus, the first temperature raised to a uniform temperature is obtained.
The heat of the layer 1-1 passes through the second layer 2-2 with extremely low heat resistance due to the effect of the enlarged and wide heat transfer area, and the heat of the third layer passes through the third layer.
Conducted to layer 3-2. Since the third layer 2-2 also has good thermal conductivity, the temperature uniformity performance of this layer also complements the temperature uniformity performance of the graphite sheet. Therefore, the temperature uniformity performance of the inter-surface heat transfer plate 1 is more and more variable. Less.

A graphite sheet having a thickness of 0.2 mm is used as the first layer, a silicon-based heat conductive adhesive is used as the second layer, and a pure copper thin plate having a thickness of 0.1 mm is applied as the third layer. The surface heat transfer plate of the present invention having an outer dimension of 60 mm × 60 mm was manufactured to have a thickness of 2 mm and an outer dimension of 60 mm × 6.
The performance was compared with that of a plate heat pipe containing 0 mm Freon 142b working fluid. The performance was measured as shown in FIG. 2 and a small heat-generating element with a heat dissipation area of 13 mm x 13 mm was used.
A heat sink having a heat receiving area of 50 mm × 50 mm was mounted. The thermal resistance value at a heat input of 12 W and a cooling convection of 0.2 m / s is 5.1 ° C./W for the inter-surface heat transfer plate and 5.04 ° C./W for the plate heat pipe. Was. Temperature uniformity is ± 1 of heat transfer plate between surfaces
The temperature of the plate heat pipe was ± 1.5 ° C., which was better than that of the plate heat pipe of the present invention. From these results, it is clear that if the inter-surface heat transfer plate of the present invention is configured to have a thickness of 0.5 mm or more, the performance is far higher than that of a plate heat pipe having a thickness of 2 mm.
In the case of such a small plate, it was determined that the inter-surface heat transfer plate of the present invention was extremely advantageous over the plate heat pipe.

[0015]

【Example】

[First Embodiment] The inter-surface heat transfer plate 1 according to the present invention can be formed in a thin shape having a thickness of 1 mm or less. In this case, it is often used after bending. Also, since it is very thin, it is often bent during use. In addition, since the plate is a heat transfer plate, it is inevitable that the plate undergoes high and low temperature cycles. In these cases, depending on the metal material of the third layers 3-1 and 3-2, the first layer 1-
The second layer 2-
Significant stress is applied to 1, 2-2. The first embodiment prevents delamination in the second layers 2-1 and 2-2 in the above-described case, and prevents performance degradation due to cutting of the second layers 2-1 and 2-2. It is an embodiment for the purpose. In this embodiment, a thin-film layer of a rubber-like elastic adhesive having high spreadability is applied to the second layers 2-1 and 2-2, and the spreadability and flexibility are applied to the third layers 3-1 and 3-2. The method is performed by applying a thin metal layer having high thermal conductivity, which is rich in properties.

[Second Embodiment] The second embodiment has a configuration that exhibits higher functions than the first embodiment. In FIG. 1, the third layers 3-1 and 3-2 are thin metal layers having high spreadability and flexibility and high thermal conductivity, and the second layers 2-1 and 2-2 have high expandability and the third layer. It is a thin film layer of an alloy material having a lower melting point than the metal forming the layer. In the case of the first embodiment, there is a problem that the application temperature range of the inter-surface heat transfer plate 1 is limited by the application temperature range of the adhesive. The application temperature range of the adhesive having good heat conductivity is 200 ° C. or less. In this embodiment, the second layer 2
Since the alloy layers having lower melting points than the thin metal layers of the third layers 3-1 and 3-2 are applied as the adhesives of the first and second layers, the third layers 3-1 and 3-2 are made of aluminum. 60 for
The applicable temperature range is greatly expanded to 0 ° C. or less, and in the case of pure copper to 1000 ° C. or less. Although the graphite sheet is not considered to have good adhesiveness to metal, it is possible to obtain a practically acceptable adhesion by vacuum welding under high pressure. In the implementation, the outer edge of the graphite sheet,
The outer edges of the third layers 3-1 and 3-2 are formed slightly larger than the outer edges of the second alloy layer, and the third layer 3-1 and the third layer 3-2 are simultaneously formed with the welding of the alloy layers. Are directly welded or brazed to each other to additionally form an outer edge portion which is a completely welded portion, whereby the reliability of joining with the graphite sheet by welding the second layer can be improved. The second embodiment also has a great advantage in that the thermal conductivity is greatly improved as compared with the adhesive bonded plate of the first embodiment.

Third Embodiment The inter-surface heat transfer plate 1 of the present invention can be formed to be extremely thin, but in that case, it is too flexible and may cause difficulty in mounting. The third embodiment is an embodiment in which the measures are taken. In this embodiment, the layers on both surfaces constituting the third layers 3-1 and 3-2 are
The layer 3-1 on the side to which the small heat-generating element 5 having a small area of the heat radiating section 5-1 is adhered is composed of a thin metal layer having high heat conductivity and extensibility and flexibility. Wide heat dissipation means 6
The layer 3-2 on the surface to be bonded is formed of a tough metal layer having poor flexibility. In this case, the layer on the side where the small heat generating element 5 having a small heat transfer area is bonded must be formed of a thin metal layer having a high heat conductivity, and the layer on the heat dissipating means side having a large heat transfer area slightly sacrifices the heat conductivity. Even so, it can be constituted by a strong thin metal layer having poor flexibility. With such a configuration, the inter-surface heat transfer plate 1 can have a strong structure as a whole.

[Fourth Embodiment] Since the inter-surface heat transfer plate 1 of the present invention can be formed to be extremely thin, the mechanical strength is inevitably reduced. Therefore, when an adhesive is used for mounting, the small heating element 5 may be easily deformed and disassembled when it is disassembled and peeled for replacement of the small heating element 5 or the like, and may not be used again. In the case of mounting with an adhesive, it is necessary to perform pressure bonding to avoid an increase in thermal resistance, and in many cases, deformation of the inter-surface heat transfer plate 1 due to the pressure bonding is caused. The fourth embodiment has a configuration in which those measures are taken.
In FIG. 1, the fourth layers 4-1 and 4-2 are melted or softened at a predetermined temperature, and have a heat bonding function that does not require pressurization when bonding to the heat radiating surface of the heating element or the heat receiving surface of the heat radiating means. In this case, it is a thin film layer of a low-melting-point metal having both functions of a heat-peeling function that needs to apply a strong external force.

[0019]

According to the present invention, it has become possible to provide a small inter-plane heat transfer plate which is as thin as 1 mm or less and 0.2 mm in thickness, which cannot be realized with a plate heat pipe. Its heat diffusion performance and temperature equalization performance show much better performance than plate heat pipes. Furthermore, its density can be made lower than aluminum,
The application temperature range is wider than that of the heat pipe. Such ultra-thin, ultra-light,
In addition, the inter-surface heat transfer plate having better heat diffusion performance than the heat pipe is used for aircraft equipment, space equipment, mobile communication equipment, heat diffusion of semiconductor heating elements such as portable computers,
It is expected to be widely used for heat dissipation.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view illustrating a basic structure of an inter-surface heat transfer plate according to the present invention.

FIG. 2 is an explanatory view showing an application state of the inter-surface heat transfer plate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 surface heat transfer plate 1-1 central layer 2-1 second layer 2-2 second layer 3-1 third layer 3-2 third layer 4-1 fourth layer 4-2 fourth layer 5 small heat generation Element 5-1 Heat radiating part of small heat generating element 6 Heat radiating means 6-1 Heat receiving part of heat radiating means

Claims (5)

[Claims] An inter-surface heat transfer plate for uniformly dispersing heat input from a small-area heat-receiving surface to transfer heat to a large-area heat-dissipating surface, the heat-transfer plate having extremely high surface-direction thermal conductivity, A second layer sandwiching the center layer, the center layer being a graphite thin sheet layer of a type having a low thermal conductivity in the vertical direction penetrating the surface, and a thin layer of an adhesive having a thickness that can ignore thermal resistance;
It is a thin metal layer with high thermal conductivity, consisting of a central layer and a third layer sandwiching all of the second layer, and is not an essential component on the outer surface of the third layer. The fourth layer, which is a thin film layer for adding a function, is coated, and the center layer, the second layer, and the third layer are adhered to each other at a predetermined temperature and a predetermined pressure to be laminated. A heat transfer plate between surfaces. 2. The method according to claim 1, wherein the second layer is a thin film layer of a rubber-like elastic adhesive which is rich in extensibility, and the third layer is a thin metal layer having high heat conductivity which is rich in extensibility and flexibility. The inter-surface heat transfer plate according to claim 1. 3. The third layer is a thin metal layer having high ductility and flexibility and high thermal conductivity, and the second layer is rich in malleability and the third layer.
The inter-surface heat transfer plate according to claim 1, wherein the heat transfer plate is a thin film layer of an alloy material having a lower melting point than a metal forming the layer. 4. One of the two layers constituting the third layer is a thin metal layer of high thermal conductivity, which is rich in extensibility and flexibility,
The inter-surface heat transfer plate according to claim 1, wherein the other single-sided layer is a tough metal layer having poor flexibility. 5. The fourth layer is a thin film layer of a low melting point metal that melts or softens at a predetermined temperature and has both a heat bonding function and a heat peeling function with respect to a heat radiating surface of a heating element or a heat receiving surface of a heat radiating means. The intersurface heat transfer plate according to claim 1, wherein: