JP2020072219A - Graphite structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graphite structure having high heat dissipation while eliminating powder falling of graphite. SOLUTION: The graphite structure has a graphite plate, a thermoplastic resin provided on the surface of the graphite plate and containing at least one kind of condensable polymer, and at least one kind of thermosetting resin. A resin layer is provided, and the resin layer is continuously cured by dispersing and curing the heat-curable resin, and the surface of the graphite plate is continuously covered with the thermoplastic resin containing the condensing polymer so as to cover the periphery of the heat-curable resin. Is in close contact with. [Selection diagram] FIG. 1C

Description

  The present invention relates to a graphite structure capable of managing heat emitted from a heat source such as an electronic device.

  In recent years, with the miniaturization of electronic devices, the need to dissipate heat from the electronic devices has increased. Therefore, management is becoming an increasingly important factor in the design of electronic products. Both performance reliability and expected life of electronic devices are inversely proportional to the component temperature of the device. For example, lowering the operating temperature of a device, such as a typical silicon semiconductor, can increase the processing speed, reliability, and expected life of the device. Therefore, the most important thing to achieve maximum component life and reliability is to control the operating temperature of the device within the limits set by the designer.

  A carbon material typified by graphite is drawing attention as a material excellent in such heat management. Graphite has thermal conductivity equivalent to that of aluminum and copper, which are common high thermal conductivity materials, and has heat transport characteristics superior to copper, so it can be used for heat spreaders of LSI chips, heat sinks of semiconductor power modules, etc. It is attracting attention as a material for heat radiation fins used in.

  However, a carbon material is liable to have powder falling off at the end due to its structure, and therefore a method for improving the surface condition has been proposed. For example, as shown in Patent Document 1, a laminated structure has been proposed in which films are arranged on both sides of a graphite sheet and the films are adhered to each other. Patent Document 2 proposes a structure in which the surface of graphite is coated with an organic polymer film by an electrodeposition method. Further, Patent Document 3 proposes a structure in which a surface of graphite is covered with a reaction-curable vinyl polymer as an adhesive resin composition.

JP-A-11-268976 JP, 2002-004089, A JP, 2006-306068, A

  However, in Patent Document 1, since the film has a low adhesiveness to graphite, air bubbles are generated on the surfaces of the film and the graphite, and the adhesion and the thermal conductivity are significantly reduced. Further, in the electrodeposition method of Patent Document 2, since the adhesiveness is likely to vary and the thickness of the coating film is difficult to control, stable thermal conductivity cannot be ensured. Further, in Patent Document 3, coating with an adhesive resin composition is attempted, but as in Patent Document 1, bonding by adhesion does not sufficiently adhere to graphite having a small surface roughness, and peeling on the surface occurs. Cannot be prevented.

  The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a graphite structure having high adhesion and high heat dissipation.

In order to achieve the above object, a graphite structure according to the present invention is a graphite plate,
A resin layer that is provided on the surface of the graphite plate and that includes at least one type of thermoplastic resin containing a condensable polymer and at least one type of thermosetting resin;
Equipped with
The resin layer is cured by dispersing the thermosetting resin, and the thermoplastic resin containing the condensable polymer continuously adheres to the surface of the graphite plate so as to cover the periphery of the thermosetting resin. is doing.

  According to the graphite structure of the present invention, it is possible to provide a graphite structure having a resin layer capable of maintaining high adhesion and heat dissipation on the surface of the graphite plate.

FIG. 3 is a schematic partial cross-sectional view showing the cross-sectional structure of the end portion of the graphite structure according to the first embodiment. It is a plane enlarged view of a part A of the surface of the resin layer of the graphite structure of FIG. 1A. FIG. 1B is a partially enlarged cross-sectional view of a boundary portion B between the graphite plate and the resin layer of the graphite structure of FIG. 1A. It is a TEG schematic diagram of the heat conductivity evaluation test in Embodiment 1, an example, and a comparative example.

A graphite structure according to a first aspect includes a graphite plate,
A resin layer that is provided on the surface of the graphite plate and that includes at least one type of thermoplastic resin containing a condensable polymer and at least one type of thermosetting resin;
Equipped with
In the resin layer, the cured thermosetting resin is dispersed, and the thermoplastic resin containing the condensable polymer continuously covers the surface of the graphite plate so as to cover the periphery of the thermosetting resin. It is in close contact.

  A graphite structure according to a second aspect is the graphite plate according to the first aspect, wherein the graphite plate has a thermal conductivity in the plane direction of 1000 W / m · K or more and a thermal conductivity in the thickness direction of 10 W / m · K or less. May be

  The graphite structure according to a third aspect is the graphite structure according to the first or second aspect, wherein the condensable polymer has a 6-membered ring, such as polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzo. Even if it consists of at least one of the group consisting of oxazole, polybenzobisoxazole, polypyromellitimide, aromatic polyamide, polyphenylenebenzimidazole, polyphenylenebenzobisimidazole, polythiazole, and polyparaphenylenevinylene. Good.

  A graphite structure according to a fourth aspect is the graphite structure according to any one of the first to third aspects, wherein the thermosetting resin is a phenol resin, an epoxy resin, a melamine resin, a urea resin, an unsaturated polyester resin, an alkyd resin. It may be composed of at least one of the group consisting of thermosetting polyimide.

  A graphite structure according to a fifth aspect is the graphite structure according to any one of the first to fourth aspects, wherein the thermosetting resin has a major axis of 0.5 to 1.5 μm and a height of 0.5 to 2.0 μm. Then, it may be cured in an island shape.

  The graphite structure according to a sixth aspect is the graphite structure according to any one of the first to fifth aspects, wherein the resin layer has a surface roughness of a side close to the surface of the graphite plate that is close to that of the graphite plate. You may have the surface which becomes 20-40% rough with respect to roughness.

  In the graphite structure according to a seventh aspect, in any one of the first to sixth aspects, the resin layer may have a thickness of 5 to 10 μm.

  The graphite heat sink according to the eighth aspect uses the graphite structure according to any one of the first to seventh aspects as a fin.

Hereinafter, a graphite structure according to an embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are designated by the same reference numerals.
(Embodiment 1)
FIG. 1A is a schematic partial cross-sectional view showing a cross-sectional structure of an end portion of graphite structure 10 according to the first embodiment. FIG. 1B is an enlarged plan view of a part A of the surface of the resin layer 2 of the graphite structure 10 of FIG. 1A. FIG. 1C is a partially enlarged sectional view of a boundary portion B between the graphite plate 1 and the resin layer 2 of the graphite structure 10 of FIG. 1A.
This graphite structure 10 includes a graphite plate 1 and a resin layer 2 provided on the surface thereof. That is, the entire surface of the graphite plate 1 is covered with the resin layer 2 to form the graphite structure 10. The resin layer 2 includes a thermoplastic resin 202 containing at least one type of condensable polymer and at least one type of thermosetting resin 201. Further, the cured thermosetting resin 201 is dispersed in the resin layer 2. Further, a thermoplastic resin 202 containing a condensable polymer is continuously adhered to the surface of the graphite plate 1 so as to cover the periphery of the thermosetting resin 201.
According to this graphite structure 10, the resin layer 2 is in close contact with and covers the entire surface of the graphite plate 1. Therefore, it is possible to achieve the effect of high heat dissipation while eliminating the fall of graphite powder. Further, this graphite structure 10 is useful as a graphite heat sink by using it as a fin.

  Members constituting the graphite structure 10 will be described below.

<Graphite plate>
The graphite plate 1 includes a polyoxadiazole, a polybenzothiazole, a polybenzobisthiazole, a polybenzoxazole, a polybenzobisoxazole, a polypyromellitimide, an aromatic polyamide, a polyphenylenebenzimidazole, a polyphenylenebenzobisimidazole, One or more polymer films of at least one kind of the group consisting of polythiazole and polyparaphenylene vinylene are laminated and fired while controlling the applied pressure to form a graphitized graphite plate. In this example and the comparative example, the graphite plate 1 is manufactured from one kind of polyoxadiazole, but two or more kinds of polymer films may be combined, and the graphite plate 1 is limited to the example and the comparative example. is not.

  The graphite plate 1 has, for example, a thermal conductivity in the plane direction of 1000 W / m · K or more and a thermal conductivity in the thickness direction of 10 W / m · K or less.

<Resin layer>
The resin layer 2 includes a thermoplastic resin 202 containing at least one type of condensable polymer and at least one type of thermosetting resin 201. Further, the resin layer 2 has the cured thermosetting resin 201 dispersed therein, and the thermoplastic resin containing the condensable polymer is continuously adhered to the surface of the graphite plate so as to cover the periphery of the thermosetting resin. is doing.
The resin layer 2 has, for example, a surface whose surface roughness close to the surface of the graphite plate 1 is 20-40% rougher than the surface roughness of the graphite plate.

<Condensable polymer>
Most of the condensable polymers are generally thermosetting ones, but there are thermoplastic ones. For example, in the case of a polyimide resin, generally aromatic tetracarboxylic dianhydride and aromatic diamine are starting materials. By introducing a thermally stable functional group other than an imide group or an aromatic atomic group into the starting material to reduce the concentration of the produced imide group in the repeating unit, the thermoplastic property is improved. You can have it.
The condensable polymer has, for example, a polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, polypyromellitimide, aromatic polyamide, polyphenylenebenzoi having a six-membered ring. It comprises at least one member selected from the group consisting of mitazole, polyphenylene benzobisimidazole, polythiazole and polyparaphenylene vinylene. The condensable polymer in some of the examples and comparative examples is a thermoplastic resin prepared from one polyoxadiazole, but a condensable polymer having two or more 6-membered rings may be combined. Of course, the invention is not limited to this example and the comparative example.

<Thermosetting resin>
Further, the thermosetting resin is at least one selected from the group consisting of phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, and thermosetting polyimide. In this example and the comparative example, the thermosetting resin layer is made from one kind of the phenol resin, but two or more kinds of the thermosetting resin may be combined and is limited to the present example and the comparative example. Not a thing.

  The state of the thermosetting resin 201 dispersed and cured is schematically shown in the plan enlarged view of FIG. 1B and the partially enlarged sectional view of FIG. 1C. As shown in FIGS. 1B and 1C, the thermosetting resin 201 is dispersed and hardened into an elliptic sphere in the thermoplastic resin layer 202 containing the condensable polymer. At this time, the thermoplastic resin layer 202 containing the condensable polymer exists between the thermosetting resin 201 and the graphite plate 1, and the thermosetting resin 201 and the graphite plate 1 do not come into contact with each other. The major axis 3 of the thermosetting resin 201 in the plan enlarged view (FIG. 1B) is 0.5 to 1.5 μm, and the height 4 of the thermosetting resin 201 in the enlarged sectional view (FIG. 1C) is 0.5 to 2.0 μm. Is preferred. Particularly preferably, the major axis is 0.8 to 1.2 μm and the height is 1.0 to 1.5 μm. If the major axis is less than 0.5 μm and the height is less than 0.5 μm, the surface roughness is not roughened by 20% or more, and the heat dissipation effect due to the increase in the surface area cannot be obtained. On the other hand, when the major axis is more than 1.5 μm and the height is more than 2.0 μm, the surface roughness is more than 40% and the surface is roughened, so that the heat conduction by the resin layer 2 is significantly reduced and the heat radiation effect is reduced. The thickness 5 of the resin layer is preferably 5 to 10 μm. If it is less than 5 μm, the adhesiveness cannot be maintained. When it exceeds 10 μm, the heat conduction due to the resin layer is significantly reduced, and the heat dissipation effect is reduced.

  According to the graphite structure of this structure, high adhesion due to a chemical bond with graphite by a thermoplastic resin containing a condensable polymer and surface-roughening due to island-like curing of the thermosetting resin cause heat dissipation. It is possible to achieve both the effects of improving

(Example 1)
The graphite structure according to Example 1 was manufactured as follows.
As the graphite plate 1, a pressure laminated product of highly oriented graphite having a length of 50 mm, a width of 50 mm and a thickness of 0.2 mm was used. As a starting material, polyoxadiazole was used as a polymer film, and a plurality of layers were laminated and fired while controlling the applied pressure to obtain a graphitized graphite plate (Ra = 3.6 μm). For the resin layer, a thermoplastic resin containing polyoxodiazole as a condensable polymer and a phenol resin as a thermosetting resin were used. The graphite plate 1 is dipped in a solution containing an additive and cured at 180 ° C. for 30 minutes to form a resin layer. A graphite structure having a resin layer thickness of 8 μm, a thermosetting resin major axis 1.0 μm, a height 1.5 μm, and a surface roughness Ra = 4.8 μm (roughening rate 33%) was prepared.

  As the heat sink for evaluating thermal conductivity, an aluminum base having a fin base of 50 mm, a thickness of 5 mm, grooves of 2 mm, a number of 8 and a pitch of 4 mm was used. Further, at the time of crimping, 0.06 mm aluminum was pressed into the graphite structure with a pressure of 15 t to produce a graphite heat sink.

(Example 2)
In Example 2, except that the manufacturing conditions were such that the thickness of the resin layer was 5 μm, the major axis of the thermosetting resin was 0.5 μm, the height was 0.5 μm, and the surface roughness was Ra = 4.3 μm (roughening rate 20%). A graphite structure was prepared in the same manner as in Example 1.

(Example 3)
As Example 3, except that the manufacturing conditions were as follows: resin layer thickness 10 μm, thermosetting resin major axis 1.5 μm, height 2.0 μm, surface roughness Ra = 5.0 μm (roughening rate 40%). A graphite structure was prepared in the same manner as in Example 1.

(Comparative Example 1)
As Comparative Example 1, a graphite structure was produced in the same manner as in Example 1 except that the graphite plate was covered with a resin layer produced by using polyester as the condensable polymer.

(Comparative example 2)
As Comparative Example 2, except that the manufacturing conditions were such that the thickness of the resin layer was 3 μm, the major axis of the thermosetting resin was 0.4 μm, the height was 0.3 μm, and the surface roughness was Ra = 4.1 μm (roughening rate 15%). A graphite structure was prepared in the same manner as in Example 1.

(Comparative example 3)
As Comparative Example 3, except that the resin layer thickness was 15 μm, the thermosetting resin major axis was 1.8 μm, the height was 2.4 μm, and the surface roughness was Ra = 5.2 μm (roughening rate 45%). A graphite structure was prepared in the same manner as in Example 1.

<Evaluation method>
The samples prepared in Examples and Comparative Examples were subjected to an adhesion test at the graphite-resin layer interface and a thermal conductivity evaluation test when used as a heat sink.

(Adhesion test)
A tape was attached to the entire surface of the graphite structure, and the graphite surface was peeled off at a speed of 1 mm / s in the vertical direction at an angle of 90 degrees, and the peeled surface at that time was evaluated. When the peeling surface was graphite, it was evaluated as ◯, and when only the resin layer was peeled, as ×.

(Thermal conductivity evaluation test)
FIG. 2 is a TEG schematic diagram of the thermal conductivity evaluation test in the first embodiment, the example, and the comparative example. In the drawings, for convenience, the press-fitting direction of the graphite fin 102 into the fin base 103 is shown as the −z axis direction. Further, the extending direction of the fin base 103 is the x-axis direction. In the evaluation in the forced cooling environment, a temperature measuring unit 108 (□ 10 mm, t5 mm, made of copper), a heater 110 (□ 10 mm, directly below the center of the graphite heat sink manufactured by using the graphite structure described in the above-mentioned Examples and Comparative Examples as a fin. 0.3 mm of grease 107 is applied to and adhered to t1 mm, made of ceramic), and a fan 109 (model number UDQF56C11CET (Panasonic)) having a size of □ 50 mm is installed directly above the heater and fan when operating at 11 V input. The temperature at the boundary between the heater and the heat sink was measured and evaluated.

In addition, as the evaluation criteria, the graphite heat sink having a fin made of a graphite plate without a resin layer in the related art was evaluated as ◯ when the temperature of the measurement portion was low, and as x when it was high.

The conditions in Examples and Comparative Examples are shown in Table 1.

  Table 2 shows the evaluation results of the examples and comparative examples.

  According to Table 1 and Table 2, in Example 1, with respect to the graphite plate, polyoxadiazole was used as the condensable polymer and phenol was used as the thermosetting resin as the resin layer. The graphite structure obtained in Example 1 had a resin layer thickness of 8 μm, thermosetting resin major axis 1.0 μm, height 1.5 μm, and surface roughness Ra = 4.8 μm (roughening rate 33%). )Met. In this graphite structure, sufficient adhesion due to a chemical bond was exhibited at the interface between the graphite and the resin layer. As for the heat dissipation effect, the temperature of the measurement part has dropped by 1 ° C or more due to the increase of the forced air cooling effect due to the increase of the surface area compared to the one using the graphite plate without the resin layer. You can see that it is exerting. In the graphite structures obtained in Examples 2 and 3, the resin layer has a thickness of 5 to 10 μm, the thermosetting resin has a major axis of 0.5 to 1.5 μm, and a height of 0.5 to 2.0 μm. The surface roughness was Ra = 4.3 μm (roughening rate 20%) to 5.0 μm (roughening rate 40%). It can be seen that these graphite structures also have sufficient adhesiveness at the interface and a sufficient heat dissipation effect for the graphite plate without the resin layer.

  On the other hand, as shown in Comparative Example 1, when a polyester having no six-membered ring is used among the condensable polymers, the adhesion with graphite is poor, and the heat dissipation effect cannot be expected because air is contained inside. .. Further, as shown in Comparative Example 2, when the resin layer is too thin, the adhesion is poor and the amount of surface area expansion is small, so a sufficient heat dissipation effect cannot be obtained. Furthermore, as shown in Comparative Example 3, if the resin layer is too thick, the heat insulating effect of the resin is increased, and the heat dissipation is rather deteriorated.

  It should be noted that the present disclosure includes appropriate combination of any of the various embodiments and / or examples described above, and each of the embodiments and / or The effects of the embodiment can be achieved.

  INDUSTRIAL APPLICABILITY The graphite structure according to the present invention can be applied to heat dissipation of heat generating parts in industrial equipment and in-vehicle fields.

1 Graphite Plate 2 Resin Layer 3 Long Diameter of Thermosetting Resin 4 Height of Thermosetting Resin 5 Thickness of Resin Layer 10 Graphite Structure 201 Thermosetting Resin 202 Thermoplastic Resin Layer 101 Condensable Polymer 101 Graphite Heat Sink 102 Graphite fin 103 Fin base 104 Metal press-fitting part 105 Caulking groove 106 Metal press-fitting amount 107 Grease 108 Temperature measuring part (thermocouple)
109 fan 110 heater 111 support plate

Claims (8)

Graphite plate,
A resin layer that is provided on the surface of the graphite plate and that includes at least one type of thermoplastic resin containing a condensable polymer and at least one type of thermosetting resin;
Equipped with
In the resin layer, the cured thermosetting resin is dispersed, and the thermoplastic resin containing the condensable polymer continuously covers the surface of the graphite plate so as to cover the periphery of the thermosetting resin. A graphite structure that is in close contact.   The graphite structure according to claim 1, wherein the graphite plate has a thermal conductivity in the plane direction of 1000 W / m · K or more and a thermal conductivity in the thickness direction of 10 W / m · K or less.   The condensable polymer has a 6-membered ring, polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, polypyromellitimide, aromatic polyamide, polyphenylenebenzimidazole. The graphite structure according to claim 1 or 2, wherein the graphite structure is made of at least one selected from the group consisting of polyphenylene benzobisimidazole, polythiazole, and polyparaphenylene vinylene.   4. The thermosetting resin comprises at least one selected from the group consisting of phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, and thermosetting polyimide. The graphite structure according to any one of 1.   5. The thermosetting resin has a major axis of 0.5 to 1.5 μm, a height of 0.5 to 2.0 μm, and is cured in an island shape. The graphite structure according to 1.   6. The resin layer has a surface having a surface roughness that is 20 to 40% rougher than that of the surface of the graphite plate, the surface roughness being close to the surface of the graphite plate. The graphite structure according to any one of items.   The graphite structure according to any one of claims 1 to 6, wherein the resin layer has a thickness of 5 to 10 µm.   A graphite heat sink using the graphite structure according to any one of claims 1 to 7 as a fin.

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