JP2001068608A - Heat conductor and electric and electronic equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat conductor exhibiting a physical flexibility, an ease of work such as cutting, a good adhesion to other parts, a light weight, a high degree of freedom of shape and a high heat-radiation and electric and electronic equipment precluding effects of heat by using the heat conductor. SOLUTION: The heat conductor is formed of a porous graphite film which is formed by firing high-heat-resistant polymers having a porous construction with a series of micropores of average pore size of 0.1-10 μm and with a porosity of 15-85% at a high temperature and in an anaerobic atmospheric and the electric and electronic equipment have a heat generator and a cooling device or a heat radiator and use the heat conductor for linking between the heat generator and the cooling device or the heat radiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat conductor made of a porous graphite film or the like and an electric / electronic device using the same, and more particularly to an anisotropic graphite film having excellent heat conductivity. The present invention relates to electronic / electrical devices, optical devices, and related devices used for the purpose. In the present specification, a continuous hole refers to a so-called open hole in which pores extend from any surface to another surface in a passage-like manner, preferably those in which the pores non-linearly pass through a winding passage. Say.

[0002]

2. Description of the Related Art Conventionally, with regard to thermal problems of electronic / electrical devices, optical devices, and related devices / apparatuses using them, in the era of high-density mounting or high integration, external space has not been developed. And the like, indirect cooling with the addition of fin-shaped members, and direct cooling by providing a cooling fan in part.

In this case, a Cu plate or an Al plate, which is a metal plate having good thermal conductivity, may be used in order to secure an effective heat radiation effect. Alternatively, a powdered material having excellent thermal conductivity may be molded under pressure for lightening or the like, or may be dispersed in resin and molded into a sheet.

[0004] For example, carbon sheet can be obtained by press-molding graphite powder which has been treated with an acid or the like having a certain particle size, and has a thermal conductivity of 400 W / K · m for Cu. Is about 100 to 200 W / K · m.

Further, graphite sheets are disclosed in
No. 127,289, JP-A-61-148265, JP-A-60-115418, etc., all of which are disclosed as being obtained by firing a suitable polymer material at a high temperature. I have.

Further, Japanese Patent Application Laid-Open No. H11-26662 discloses an electric apparatus using a graphite film having a high degree of freedom in shape, light weight, and excellent heat dissipation and heat uniformity as a heat conductor. ing. It discloses that firing is performed under a temperature condition having foaming properties to obtain a porous graphite film having a low density.

However, the porous graphite film is
Although having excellent heat conduction, low density, and flexibility, it is difficult to control the pores by foaming only under the firing temperature conditions.

[0008] Recently, various electronic components including semiconductor elements, devices using the electronic components, and the like have been further increased in speed, size, integration, and weight. For example, in a semiconductor device, a heat generation amount during driving has been remarkably increased with the progress of high performance such as high speed and high integration. And
In a device incorporating such a semiconductor element, this heat generation has a great effect. This is because the device itself tends to be smaller and lighter, so that heat tends to be trapped in the space of the reduced circuit, and phenomena that adversely affect the performance of other elements increase.

[0009] For example, in a display element, although higher definition has been advanced and higher quality of image quality has been further desired, temperature distribution between pixels may greatly affect image quality itself. In this case, the affected heat source includes an electric source at the time of driving, a backlight in the case of a passive element, and radiant heat from other sources.

In addition, for example, recording / recording using a laser light source
Also in reproduction, the temperature of the desk substrate and the laser light source is regarded as important in terms of stability and reliability during recording and reading, and it is required that the temperature be within a predetermined temperature range in terms of stability and reliability.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to have physical flexibility, ease of processing such as cutting, good adhesion to other parts, light weight, high degree of freedom in shape, and It is an object of the present invention to provide a heat conductor having excellent heat dissipation properties, and an electric / electronic device using the heat conductor to eliminate the influence of heat.

[0012]

The present invention has a porous structure having fine continuous pores and an average pore diameter of 0.1 to 10 μm.
The present invention relates to a heat conductor comprising a porous graphite film obtained by firing a high heat-resistant polymer having a porosity of 15 to 85% in an anaerobic atmosphere at a high temperature. Further, the present invention relates to an electric / electronic device having a heat source and a cooling source or a heat radiating source, and using the above-mentioned heat conductor to communicate between the heat generating source and the cooling source or the heat radiating source.

[0013]

Embodiments of the present invention will be described below. 1) The above-mentioned heat conductor in which the high heat-resistant polymer is polyimide. 2) A porous film of a high heat-resistant polymer is formed by casting a solution comprising a polyimide precursor into a film and bringing the solution into contact with a coagulating solvent through a solvent displacement rate controlling material to precipitate the polyimide precursor. The above thermal conductor, which is obtained by obtaining a polyimide precursor porous film having fine continuous pores and then subjecting the polyimide precursor porous film to a thermal imidization treatment or a chemical imidization treatment. 3) An element, a light source, and a heat source that generate heat by electric driving.
The electric device as described above, which is one of display elements.

The heat conductor of the present invention has a porous structure having fine continuous pores, a high heat-resistant polymer film having an average pore diameter of 0.1 to 10 μm and a porosity of 15 to 85% in an anaerobic atmosphere. It is a heat conductor made of a graphite film which is baked at a high temperature to be graphitized. If the average pore diameter of the porous high heat resistant polymer film to be carbonized is less than 0.1 μm, when used for a heat conductor, the flexibility becomes insufficient,
You may not be able to perform the functions you expect. On the other hand, if the average pore diameter exceeds 10 μm, the mechanical strength of the heat conductor is similarly deteriorated. The average pore size of the porous graphite film forming the thermal conductor of the present invention can be adjusted by the average pore size of the graphitized polyimide film.

The anaerobic atmosphere needs to be free of oxidizing gas such as oxygen, and suitable anaerobic gas is argon, helium, nitrogen or the like. Particularly, an argon atmosphere is preferable.

Examples of the high heat-resistant polymer in the present invention include a polymer having high molecular weight and high heat resistance by polycondensation of an aromatic acid component and an aromatic diamine component and heating, preferably an aromatic polyimide. Hereinafter, the case where the high heat-resistant polymer is an aromatic polyimide will be described.

A porous polyimide film, which is a typical example of a porous film of a high heat-resistant polymer film used in the present invention, can be produced, for example, by the following method.
The polyimide precursor solution cast is brought into contact with a coagulating solvent via a solvent replacement rate adjusting material to precipitate a polyimide precursor, to make it porous, and then to thermally imidize the porous polyimide precursor film or It is chemically imidized to produce a porous polyimide film.

The above-mentioned polyimide precursor is a polyamic acid obtained by polymerizing a monomer, preferably an aromatic compound, of a tetracarboxylic acid component and an aromatic diamine component, or a partially imidized polyamic acid. The ring can be closed by heat treatment or chemical treatment to obtain a polyimide resin. The polyimide resin is a heat-resistant polymer having an imidization ratio of about 50% or more, preferably about 75% or more, and particularly preferably 90% or more.

The organic solvent used as the solvent for the polyimide precursor is parachlorophenol, N-methyl-2.
-Pyrrolidone (NMP), pyridine, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, tetramethylurea, phenol, cresol and the like.

The tetracarboxylic acid component and the aromatic diamine component are dissolved and polymerized in an approximately equimolar amount in the above organic solvent,
Logarithmic viscosity (30 ° C., concentration; 0.5 g / 100 mL NM
A polyimide precursor having P) of 0.3 or more, especially 0.5 to 7, is produced. Further, when the polymerization is carried out at a temperature of about 80 ° C. or higher, a polyimide precursor partially imidized by ring closure is produced.

As the aromatic diamine, for example, a compound represented by the general formula (1) H2NR (R1) mA- (R2) nR'-NH2
(1) (However, in the above general formula, R or R ′
Is a direct bond or a divalent aromatic, R ₁ and R ₂ are substituents such as hydrogen, lower alkyl and lower alkoxy, and A is O, S, CO, SO ₂ , SO, CH ₂ , C ₂ (C
H ₃ ) _{2 and the} like, and m and n are integers of 1 to 4. The aromatic diamine compound represented by the formula (1) is preferred.

Specific examples of the aromatic diamine include 4,4′-diaminodiphenyl ether (hereinafter, referred to as 4,4′-diaminodiphenyl ether).
DADE), 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-
Diethoxy-4,4'-diaminodiphenyl ether and the like. The aromatic diamine component represented by the above general formula H ₂ N—R—NH ₂ may be diaminopyridine, and specifically, 2,6-diaminopyridine, 3,6-diaminopyridine, , 5-diaminopyridine, 3,4-diaminopyridine and the like. As the aromatic diamine component, two or more kinds of the above aromatic diamines may be used in combination.

Examples of the biphenyltetracarboxylic acid component include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as s-BPDA), 2,3,3 ′, 4 '-Biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as a-BPDA) is preferred, but 2,3,3', 4'- or 3,
3 ′, 4,4′-biphenyltetracarboxylic acid, or a salt of 2,3,3 ′, 4′- or 3,3 ′, 4,4′-biphenyltetracarboxylic acid or an esterified derivative thereof Is also good. The biphenyltetracarboxylic acid component may be a mixture of the above biphenyltetracarboxylic acids.

The biphenyltetracarboxylic acid component includes, in addition to the aforementioned biphenyltetracarboxylic acids, pyromellitic acid,
3 ′, 4,4′-benzophenonetetracarboxylic acid,
2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) sulfone,
Tetracarboxylic acids such as bis (3,4-dicarboxyphenyl) ether, bis (3,4-dicarboxyphenyl) thioether, butanetetracarboxylic acid, or their anhydrides, salts or esterified derivatives Is not more than 10 mol%, especially 5 mol%, based on the total tetracarboxylic acid component.
It may be replaced by a percentage of mol% or less. Further, the tetracarboxylic acid component may be a mixture of the above-mentioned respective tetracarboxylic acids.

The polyimide precursor is dissolved in the organic solvent at a ratio of 0.3 to 60% by weight, preferably 1% to 30% by weight to prepare a polyimide precursor solution (using the polymerization solution as it is). Is also good). When the proportion of the polyimide precursor is less than 0.3% by weight, the strength of the film when the porous film is produced is lowered, so that it is not appropriate. When the proportion is more than 60% by weight, it is difficult to form a uniform solution. It is suitable. The solution viscosity of the prepared polyimide precursor solution is 10 to 10,000 poise, preferably 4 to 10 poise.
0 to 3000 poise. If the solution viscosity is less than 10 poise, the strength of the film when the porous membrane is produced is reduced, so that it is not appropriate. If the solution viscosity is more than 10,000 poise, it becomes difficult to cast the film into a film. .

After the polyimide precursor solution is cast into a film, it is formed into a laminated film having a solvent replacement rate adjusting material disposed on at least one surface. There is no particular limitation on the method of obtaining the cast laminated film of the polyimide precursor solution,
A method of casting the polyimide precursor solution on a glass plate or a movable belt serving as a base, and then covering the surface of the cast material with a solvent replacement rate adjusting material; and a spray method of the polyimide precursor solution. Alternatively, a method of thinly coating the solvent replacement speed adjusting material using a doctor blade method, extruding the polyimide precursor solution from a T-die, sandwiching the polyimide precursor solution between the solvent replacement speed adjusting materials, and adjusting the solvent replacement speed on both surfaces. A method such as a method of obtaining a three-layer laminated film provided with materials can be used.

[0027] The solvent displacement rate adjusting material is such that when the multilayer film is brought into contact with a coagulating solvent to precipitate the polyimide precursor, the solvent of the polyimide precursor and the coagulating solvent can permeate at an appropriate speed. Those having permeability are preferred. The thickness of the solvent displacement rate adjusting material is 5 to 500
[mu] m, preferably 10 to 100 [mu] m, and 0.01 to 10 [mu] m, preferably 0.1 to 10 [mu] m continuous in the cross-sectional direction of the film.
It is preferable that pores of 03 to 1 μm are dispersed at a sufficient density. When the thickness of the solvent replacement rate adjusting material is smaller than the above range, the solvent replacement rate is too fast, so that not only a dense layer is formed on the surface of the precipitated polyimide precursor, but also wrinkles occur when contacting with the coagulation solvent. If it is larger than the above range, the solvent substitution rate becomes slow, and the pore structure formed inside the polyimide precursor becomes non-uniform.

As the solvent displacement rate controlling material, specifically, a nonwoven fabric or a porous film made of a polyolefin such as polyethylene or polypropylene, cellulose, Teflon or the like is used. In particular, a microporous film made of polyolefin is used. Is preferred because the surface of the produced polyimide porous film has excellent smoothness.

The multilayered polyimide precursor cast is
The polyimide precursor is precipitated and made porous by contacting with a coagulation solvent via the solvent displacement rate adjusting material. Examples of the solidifying solvent for the polyimide precursor include alcohols such as ethanol and methanol, non-solvents of the polyimide precursor such as acetone and water, or 99.9 to 50% by weight of these non-solvents and the polyimide precursor. And a mixed solvent with 0.1 to 50% by weight of the solvent. The combination of the non-solvent and the solvent is not particularly limited, but is preferably used when a mixed solvent of the non-solvent and the solvent is used as the coagulating solvent because the porous structure of the precipitated polyimide precursor becomes uniform.

The porous polyimide precursor film is then subjected to heat treatment or chemical treatment. In the heat treatment of the polyimide precursor film, the polyimide precursor porous film from which the solvent displacement rate adjusting material has been removed is fixed using a pin, chuck, pinch roll, or the like so as not to cause thermal shrinkage, and is heated to 280 in air. Performed at ５００500 ° C. for 5-60 minutes.

The chemical treatment of the polyimide precursor porous film is carried out by using an aliphatic acid anhydride or an aromatic acid anhydride as a dehydrating agent and using a tertiary amine such as triethylamine as a catalyst. Further, as disclosed in JP-A-4-339835, imidal, benzimidazole, or a substituted derivative thereof may be used.

The multilayered polyimide precursor cast is
The polyimide precursor is precipitated and made porous by contacting with a coagulation solvent via the solvent displacement rate adjusting material. Examples of the solidifying solvent for the polyimide precursor include alcohols such as ethanol and methanol, non-solvents of the polyimide precursor such as acetone and water, or 99.9 to 50% by weight of these non-solvents and the polyimide precursor. And a mixed solvent with 0.1 to 50% by weight of the solvent. The combination of the non-solvent and the solvent is not particularly limited, but is preferably used when a mixed solvent of the non-solvent and the solvent is used as the coagulating solvent because the porous structure of the precipitated polyimide precursor becomes uniform.

The porous polyimide precursor film is then subjected to heat treatment or chemical treatment. In the heat treatment of the polyimide precursor film, the polyimide precursor porous film from which the solvent displacement rate adjusting material has been removed is fixed using a pin, chuck, pinch roll, or the like so as not to cause thermal shrinkage, and is heated to 280 in air. Performed at ５００500 ° C. for 5-60 minutes.

The chemical treatment of the polyimide precursor porous film is performed by using an aliphatic acid anhydride or an aromatic acid anhydride as a dehydrating agent and using a tertiary amine such as triethylamine as a catalyst. Further, as disclosed in JP-A-4-339835, imidal, benzimidazole, or a substituted derivative thereof may be used.

The imidation ratio of the heat-treated or chemically-treated polyimide porous film is 50% or more, preferably 75% or more.
% Or more. If the imidation ratio is less than 50%, the porous polyimide film is unsuitable because it undergoes a large amount of water due to dehydration and a large amount of shrinkage due to the heat treatment during further heat treatment and carbonization.

The polyimide porous film produced in this manner has a porosity of 15
-85%, preferably 30-85%, particularly preferably 4%
0 to 70%, average pore diameter of 0.1 to 10 μm, preferably 0.1 to 5 μm and maximum pore diameter of 15 μm or less.

If the porosity is too low, when used for a heat conductor, the density is high, and the effect of the present invention is hardly obtained. If the porosity is too large, the mechanical strength will be poor. On the other hand, if the average pore diameter is too small, the pores of the heat conductor of the porous graphite film after carbonization are undesirably closed.

The polyimide porous film preferably has a film thickness of 5 to 100 μm and an air permeability of 3
It is prepared into a film having continuous holes of 0 to 2000 seconds / 100 cc.

A porous polyimide film can be produced by the above production method, and a porous carbonized film can be produced. The carbonization method is, for example, heating to a temperature of 800 ° C. in an anaerobic atmosphere, followed by firing to a temperature of 2900 ° C. and further to a temperature of 3500 ° C., or firing to a temperature higher than that,
It is preferable to carbonize. It is preferable that the porous membrane is sandwiched between air-permeable carbon plates or sheets so that the porous membrane that is being carbonized simultaneously with heating does not shrink. In this way,
A porous carbonized film can be manufactured.

As the graphite film used for the heat conductor, two or more porous polyimide films obtained by the above method may be stacked and used for a carbonized film. By doing so, a product having a thickness corresponding to the electric device can be freely manufactured. It is preferable that the thickness be in the range of 0.1 to 1 mm from the viewpoint of the production conditions of the electric furnace and the like, the degree of freedom of the shape, and the like.

The above anaerobic atmosphere needs to be free of oxidizing gas such as oxygen, and suitable anaerobic gas is argon, helium, nitrogen or the like. Particularly under an argon atmosphere is preferable.

The carbonization of the precursor is preferably carried out in an anaerobic gas stream so that the decomposed product is smoothly distilled off and the once decomposed product is not deposited again.

It is preferable that the porous polyimide film is gradually carbonized, and if the decomposition product is rapidly escaping, the carbon content is distilled off, and the carbonization yield may be reduced, which is not preferable. In addition, structural defects are likely to occur. For this purpose, it is preferable that the temperature is raised at a sufficiently low rate of not more than 15 ° C., particularly about 5 to 10 ° C./min.

Simultaneously with the heating, it is preferable to carry out carbonization while applying tension perpendicular to the film surface. This suppresses shrinkage that occurs during carbonization, and the precursor during carbonization is easily oriented. Carbides are formed. In addition, a graphite structure having high crystallinity is provided.

As a method for applying a tension perpendicular to the film surface, it is preferable to sandwich the film with a heat-resistant sheet while heating to adjust the shape of the carbonized film. Porous plates and films are preferred. For example, it is suitable for adjusting the shapes of a silicon nitride plate and a carbon film. For continuous processing, tension is applied between the rolls, while applying tension with a pin tenter,
A method of a biaxial stretching operation of drawing between rolls can be employed.

According to the invention, preferably the average pore size is 0.1
This is a method for producing a porous carbonized film obtained by heating a porous polyimide film having continuous pores of 10 to 10 μm at a temperature of 800 to 3500 ° C. in an anaerobic atmosphere. Temperature 2900
When calcined to ５００3500 ° C., carbides with a high degree of crystallinity are formed. Temperature of 3500 ° C. or more is acceptable,
If the temperature is higher than 500 ° C., the workability becomes unstable and continuous operation may not be performed. Approximately 30-60 crystallinity
%, Especially 40 to 60%, of a porous carbonized film having a graphite structure. The graphite film for a heat conductor of the present invention can be obtained by the above method.

An electric apparatus using the heat conductor of the present invention uses a graphite film having anisotropy in heat conductivity as a heat conductor, so that the direction in which the heat conduction is large is in the direction away from the heat source. An electrical device that was contacted to aim.

With such a configuration, an electric device which is free from the influence of heat is realized by using a graphite film which has a high degree of freedom in shape and is lightweight and has excellent heat dissipation and soaking properties as a heat conductor. In addition, characteristic changes and deterioration due to heat are reduced. At that time, by manufacturing a porous graphite film from a porous polyimide film having a controlled pore size and porosity, a porous graphite film having a controlled pore size and porosity is manufactured.

The thermal conductivity of the graphite film used here is 600 to 1000 W / K · m in the plane and about 5 W / K · m in the thickness direction.

Further, a cooling source or a heat radiating source may be further provided, and a heat conductor may communicate between the heat generating source and the cooling source or the heat radiating source. With this configuration, the heat radiation effect is further improved, and the influence of the characteristics due to heat is reduced.

Further, the heat conductor may be configured to connect a plurality of heat sources. With this configuration, the temperature between the plurality of heat sources is made uniform, and the effect of uneven heat is eliminated.

Further, the heat conductor may be configured to indirectly cool the heat source, thereby further improving the heat radiation effect.
Reduce the effect of heat on properties. Here, the heat source may be an element driven by electric drive, a light source, or a display element.

Further, a structure in which a plurality of display elements are connected by a heat conductor may be used, thereby suppressing the occurrence of unevenness between pixels and improving the instability of the characteristics of the display elements.

The heat conductor is preferably a flexible graphite film in consideration of the heat conductivity and the degree of freedom of form.

[0055]

The following examples and comparative examples illustrate the porous carbonized film of the present invention in more detail, but the present invention is not limited thereto. Hereinafter, in each row, the air permeability, the porosity, and the average pore diameter were measured as follows.

Air permeability Measured according to JIS P8117. A B-type Gurley densometer (manufactured by Toyo Seiki Co., Ltd.) was used as a measuring device. The sample piece is fastened to a circular hole having a diameter of 28.6 mm and an area of 645 mm ² . With the inner cylinder weight of 567 g, the air in the cylinder is allowed to pass from the test hole to the outside of the cylinder. The time required for 100 cc of air to pass was measured and defined as the air permeability (Gurley value).

Porosity The apparent density of the film was calculated from the thickness, area and weight of the porous film cut into a predetermined size, and the porosity was determined. The density of polyimide is 1340kg / m3,
The density of graphite was set at 1810 kg / m ³ .

Average pore size From a scanning electron micrograph of the surface of the porous film, 50
The hole area was measured with respect to the opening portions having points or more, and the average diameter when the hole shape was assumed to be a perfect circle was calculated from the average value of the hole areas according to the following formula. Sa in the following equation means the average value of the hole area. Average pore size = 2 × (Sa / π) 1/2

Example 1 Preparation of Precursor Porous Polyimide Film Using s-BPDA as a tetracarboxylic acid component and DADE as a diamine component, DA for s-BPDA was used.
It was dissolved in NMP so that the molar ratio of DE was 0.994 and the total weight of the monomer components was 20% by weight.
Polymerization was performed at 0 ° C. for 6 hours to obtain a polyimide precursor. The solution viscosity of the polyimide precursor solution was 500 poise.

The obtained polyimide precursor solution was cast on a glass plate so as to have a thickness of about 150 μm, and a microporous polyolefin membrane having an air permeability of 550 sec / 100 cc (Ube Industries, Ltd.) was used as a solvent replacement rate adjusting material. Company UPOR UP20
In 15), the surface was covered to prevent wrinkles. The laminate was immersed in methanol for 5 minutes, and the solvent was replaced through a solvent replacement rate adjusting material, thereby depositing the polyimide precursor and making it porous.

After immersing the deposited polyimide precursor porous film in water for 15 minutes, the polyimide precursor porous film was peeled off from the glass plate and the solvent replacement rate adjusting material, and fixed to a pin tenter.
Heat treatment was performed at 300 ° C. for 10 minutes in the atmosphere. The imidation ratio of the polyimide porous film is 80%,
The film had continuous holes in the cross-sectional direction of the film.

The measurement results of the film thickness, air permeability, porosity, and average pore size of the obtained polyimide porous film are shown below. Measurement result Film thickness 44 μm Air permeability 378 sec / cc Porosity 59% Average pore diameter 0.72 μm

Production of Porous Graphite Film Five porous polyimide films obtained as described above are superimposed, sandwiched on both sides with a gas-permeable carbon sheet in an atmosphere of argon gas, and heated at a rate of 10 ° C./min. From 20 ° C to 1000 ° C
The temperature was raised to ° C. Further, at a heating rate of 5 ° C. and a temperature of 300
The temperature was raised to 0 ° C. and maintained at a temperature of 3000 ° C. for 60 minutes. After cooling, the resulting graphite film was porous, glossy, flexible and tough. From a scanning electron microscope of this porous graphite film, the pore size was smaller than the pore size before graphitization, and the average pore size was 0.2 μm. The apparent density was 796 kg / m3, and it was confirmed from the results of a scanning electron microscope and the passage of methanol that it had fine continuous pores. According to the Ruland method of X-ray measurement, the crystallinity was 54%.
The results are shown below. Measurement result Film thickness 150 μm Air permeability 980 sec / cc Porosity 56% Apparent density 796 kg / mm ³ Average pore diameter 0.2 μm Graphite crystallinity 54%

A personal computer having an MPU (microprocessing unit) as a heat source, and a graphite film obtained as above were installed as a heat conductor, and heat dissipation was evaluated. An MPU, a cooling fan directly cooled by exhaust air, and a graphite film as a heat radiator (heat radiator: heat conductor) were cut into a predetermined size and installed to obtain an electronic device. The element surface temperature of MPU1 was set to 110 ° C. On this upper surface, thickness 1 mm, width 10 mm,
The porous graphite film having a length of 100 mm was brought into contact with the MPU 1 so as to be located substantially at the center, and the temperature at the end in the longitudinal direction was 82 ° C.

Comparative Example 1 Five polyimide films having no holes (UPIREX thickness 35 μm, manufactured by Ube Industries, Ltd.) were stacked and graphitized in the same manner as in Example 1. The density of this graphitized film was 171
0 kg / m3, which was high. The foam was partially foamed, and the pores were unevenly distributed between open and non-open areas. It was shiny and flexible. ,
According to X-ray measurement, the crystallinity was 48%. As in Example 1, the heat radiation effect of the MPU was measured. When the temperature was measured in the same manner, the temperature was 93 ° C. Example 1
The heat radiation effect was inferior to that of the case.

Example 2 A fin-like member was formed using the same graphite film as in Example 1. When the same measurement was performed in a state where the fan located at the end of the fin-shaped member was operated, the temperature reached 41 ° C. in combination with the direct cooling action. As mentioned above,
It can be seen that the use of a graphite film heat conductor, in some cases, combined with the effect of direct cooling by a fan or the like, produces a large heat dissipation effect.

Example 3 The heat radiation of a graphite film was measured using a laser light source as a heat source. A semiconductor laser as a light source, a cooling element, and a graphite film were provided. Initially, the element surface temperature of the semiconductor laser was set to 85 ° C. A graphite film having a thickness of 1 mm, a width of 10 mm, and a length of 20 mm was brought into contact with the side surface, and the temperature at the end in the longitudinal direction was 67 ° C.

Comparative Example 2 Instead of a graphite film, an Al plate was cut to the same size, laminated to the same thickness, placed in the same manner, and subjected to the same measurement. The temperature was 75 ° C. .

[0069]

According to the present invention, it is possible to provide a porous graphite film having a controlled pore size and porosity by carbonizing a heat-resistant polymer film having fine continuous pores. In addition, a graphite film having a high degree of freedom in shape and light weight and exhibiting excellent heat dissipation and soaking properties can be used as a heat conductor.
Further, according to the present invention, it is possible to realize an electric / electronic device excluding the influence of heat.

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Claims (5)

[Claims] 1. A highly heat-resistant polymer porous film having a porous structure having fine continuous pores, an average pore diameter of 0.1 to 10 μm, and a porosity of 15 to 85%, in an anaerobic atmosphere.
A thermal conductor made of a porous graphite film that is fired at high temperature and graphitized. 2. The heat conductor according to claim 1, wherein the high heat-resistant polymer is polyimide. 3. A porous film of a high heat-resistant polymer, which is obtained by casting a solution comprising a polyimide precursor into a film and bringing the solution into contact with a coagulating solvent via a solvent displacement rate controlling material. Depositing, after obtaining a polyimide precursor porous film of fine continuous pores, the polyimide precursor porous film is obtained by a thermal imidation treatment or a chemical imidization treatment. Item 2. The thermal conductor according to Item 2. 4. It has a heat source and a cooling or heat radiation source,
An electric / electronic device using the heat conductor according to claim 1 for communicating between a heat source and a cooling source or a heat radiation source. 5. The electric / electronic device using a heat conductor according to claim 4, wherein the heat source is any of an element, a light source, and a display element that generate heat by electric driving.