JP2003200437A - Method for manufacturing heat conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method high in productivity capable of easily manufacturing a heat conductive sheet having excellent heat conductivity at a low cost. <P>SOLUTION: A magnetic field is applied to a polymer composition, which is prepared by adding graphite carbon fibers to a polymeric matrix material, to orient the graphite carbon fibers by the magnetic field and this polymer composition is cured or solidified in a sheetlike state to manufacture the heat conductive sheet. In this manufacturing method, the viscosity of the polymeric matrix material at the time of the magnetic orientation of the graphite carbon fibers is set to 0.025-100 (Pas) or the viscosity of the polymer composition at the time of the magnetic orientation of the graphic carbon fibers is set to 0.15-120 (Pas). The polymeric matrix material is preferably a thermoplastic material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a heat conductive sheet having high heat conductivity. More specifically, semiconductor devices such as electrical equipment, power supplies, light sources,
The present invention relates to a method for manufacturing a heat conductive sheet having high heat conductivity that can effectively dissipate heat generated in parts and the like to the outside.

[0002]

2. Description of the Related Art In recent years, with high performance, miniaturization and weight reduction of electronic equipment, high density mounting of semiconductor packages and LSI
Due to the higher integration and higher speed, heat generated by various electronic components in electric equipment increases, and countermeasures against the heat have become a very important issue.

For this reason, conventionally, a measure has been generally taken in which a heat dissipation member such as a heat sink is attached to an electronic component or the like serving as a heat source via a heat conductive sheet having good heat conductivity. This heat conductive sheet has a function of reducing contact thermal resistance between various electronic components serving as a heat source and the heat radiating member, and efficiently conducting heat generated by the various electronic components to the heat radiating member.

As this type of heat conductive sheet, generally, a material in which a graphitized carbon fiber having an extremely high heat conductivity is dispersed and blended as a heat conductive filler in a polymer matrix material such as rubber or resin. Widely adopted. It should be noted that, by orienting the graphitized carbon fibers in the polymer matrix material in a fixed magnetic field, the high thermal conductivity in the fiber axis direction of the graphitized carbon fibers can be utilized to dramatically improve the thermal conductivity. There is something that I made. This heat conductive sheet is obtained by applying a magnetic field from the outside to a polymer composition containing graphitized carbon fibers in a polymer matrix material to orient the graphitized carbon fibers in a certain direction, and It is produced by curing or solidifying a molecular composition into a sheet.

[0005]

In recent years, in high-performance electronic equipment such as a notebook computer and a mobile phone, heat generated by various electronic parts has become higher with higher integration, higher speed, smaller size and lighter weight. The quantity is increasing. Therefore, there is a demand for a heat conductive sheet having higher heat conductivity than ever before, and a highly productive manufacturing method capable of easily and inexpensively manufacturing a heat conductive sheet having such high heat conductivity. A long-awaited realization.

However, in the above conventional manufacturing method, the degree of orientation of the graphitized carbon fibers in the polymer matrix material tends to vary depending on the conditions of the magnetic field orientation of the graphitized carbon fibers, and the orientation control is stabilized. I could not do it.
Therefore, there is a problem in that a heat conductive sheet in which graphitized carbon fibers are highly magnetically oriented in a certain direction cannot be stably manufactured at low cost.

The present invention has been made to solve the above problems, and an object thereof is a highly productive production method capable of producing a heat conductive sheet having excellent heat conductivity simply and at low cost. To provide.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 applies a magnetic field to a polymer composition containing a graphitized carbon fiber in a polymer matrix material. A method for producing a heat conductive sheet, comprising curing or solidifying the polymer composition into a sheet after orienting the graphitized carbon fibers in a magnetic field, the polymer matrix material being in the magnetic field orientation of the graphitized carbon fibers. Viscosity of 0.02
It is characterized in that it is set to 5 to 100 (Pa · s).

According to a second aspect of the present invention, a magnetic field is applied to a polymer composition containing a graphitized carbon fiber in a polymer matrix material to orient the graphitized carbon fiber, and A method for producing a heat conductive sheet, comprising hardening or solidifying a molecular composition into a sheet, wherein the polymer composition has a viscosity of 0.15 when the graphitized carbon fiber is oriented in a magnetic field.
It is characterized in that it is set to 120 (Pa · s).

The invention described in claim 3 is the method for producing a heat conductive sheet according to claim 1 or 2, wherein the polymer matrix material is a thermoplastic material.

(Operation) When the graphitized carbon fiber is oriented in the magnetic field, the viscosity of the polymer matrix material is 0.025 to 10
By setting 0 (Pa · s) or the viscosity of the polymer composition to 0.15 to 120 (Pa · s), it becomes easy to control the magnetic field orientation of the graphitized carbon fiber in the polymer matrix material. The graphitized carbon fiber can be highly oriented. Therefore, by taking advantage of the high thermal conductivity of the graphitized carbon fiber in the fiber axis direction, it is possible to easily and inexpensively manufacture a thermally conductive sheet with dramatically improved thermal conductivity.

When a thermoplastic material is used as the polymer matrix material, the viscosity of the polymer matrix material or polymer composition can be easily adjusted by controlling the temperature such as heating. Therefore, it becomes easy to control the magnetic field orientation of the graphitized carbon fibers in the polymer matrix material, and the graphitized carbon fibers in the polymer matrix material are highly oriented so that the thermal conductivity is dramatically improved. Can be manufactured easily and at low cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments embodying the present invention will be described in detail below. The thermally conductive sheet of the present embodiment, the polymer composition containing the graphitized carbon fiber in the polymer matrix material, after applying a magnetic field from the outside to orient the graphitized carbon fiber in the magnetic field, It is produced by curing or solidifying the molecular composition into a sheet.

The polymer composition is obtained by dispersing and blending graphitized carbon fibers in a polymer matrix material. When the graphitized carbon fibers are mixed in the polymer matrix material, operations such as stirring, defoaming, and kneading can be performed as necessary, and known blenders, mixers, rolls, extruders, etc. A mixing / kneading device can be used.

The polymer matrix material used here is
The material is not particularly limited, and may be selected from ordinary thermoplastic resins, thermoplastic elastomers, reaction curable resins, crosslinked rubbers, etc. according to the application and required performance, but at least it is a liquid liquid at room temperature. It is required to be a polymer matrix material, or a liquid and a polymer matrix material that is solid at room temperature and melts by heating.

Specific examples of the thermoplastic resin include polyethylene, polypropylene, ethylene-α-olefin copolymers such as ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride,
Polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyacetal, fluororesin such as polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer Polymers, ABS resins, polyphenylene ether (PPE) resins, modified PPE resins, aliphatic and aromatic polyamides,
Polyimide, polyamideimide, polymethacrylic acid esters such as polymethacrylic acid and its methyl ester, polyacrylic acid, polycarbonate, polyphenylene sulfide, polysulfone, polyethersulfone, polyethernitrile, polyetherketone, polyketone, liquid crystal polymer, silicone Examples thereof include resins and ionomers.

Specific thermoplastic elastomers include
Styrene-butadiene or styrene-isoprene block copolymer and its hydrogenated polymer, styrene-based thermoplastic elastomer, olefin-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyamide-based Examples include thermoplastic elastomers.

Specific reactive curable resins include epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester resin, diallyl phthalate resin, silicone resin,
Examples thereof include polyurethane resin, polyimide silicone resin, thermosetting polyphenylene ether resin, and modified PPE resin.

Specific cross-linked rubbers include natural rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene rubber, chlorinated polyethylene, and chlorosulfonate. Polyethylene, butyl rubber and halogenated butyl rubber, fluororubber, urethane rubber,
Examples thereof include silicone rubber.

Among these, at least one selected from silicone rubber, epoxy resin, polyurethane resin, unsaturated polyester resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, fluororesin, polyphenylene ether resin, and thermoplastic elastomer. It is preferable to use at least one polymer matrix material selected from the group consisting of silicone rubber, epoxy resin, unsaturated polyester resin, polyimide resin, polyurethane resin, and thermoplastic elastomer. It is preferable from the viewpoint of electrical reliability. In addition, for example, for wiring board applications where the dielectric constant and dielectric loss tangent are small and characteristics in the high frequency region are required,
It is preferable to use a fluororesin, a thermosetting polyphenylene ether resin, a modified PPE resin, a polyolefin resin, or the like. The curing / crosslinking method of the reactive curable resin or the crosslinked rubber is not limited to the thermosetting method, and known methods such as a photocuring method, a moisture curing method and an addition reaction method can be adopted.

On the other hand, the graphitized carbon fiber used here is not particularly limited, and known graphite such as PAN-based graphitized carbon fiber, rayon-based graphitized carbon fiber, and pitch-based graphitized carbon fiber. The carbonized carbon fiber can be appropriately selected and used, but it is particularly preferable to use a pitch-based graphitized carbon fiber having excellent thermal conductivity.

The blending amount of this graphitized carbon fiber is preferably 20 to 500 parts by weight per 100 parts by weight of the polymer matrix material. When the amount of the graphitized carbon fiber is less than 20 parts by weight, the heat conductivity of the resulting heat conductive sheet is small and the heat dissipation property is poor, which is not preferable. On the other hand, when the blending amount of the graphitized carbon fiber exceeds 500 parts by weight, it becomes difficult to uniformly disperse the graphitized carbon fiber in the polymer matrix material, and the inclusion of bubbles is unavoidable, which is not preferable. More preferably, it is 40 to 300 parts by weight per 100 parts by weight of the polymer matrix material.

If desired, other heat conductive fillers, flame retardants, colorants, stabilizers, etc. may be added to the polymer matrix material. Specific examples of the other thermally conductive fillers include metals such as silver, copper and gold, and ceramics such as aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide and aluminum hydroxide. Besides, metal-coated resin, other forms of graphitized carbon fiber, non-graphitized carbon fiber, natural graphite, artificial graphite, mesocarbon microbeads, diamond powder and the like can be mentioned. These forms include, for example, powder, fibrous, scale-like, whisker-like,
Examples include microcoils and nanotubes,
It is not particularly limited. Further, the heat conductive polymer sheet obtained as the final product, particularly in applications where electrical insulation is required, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride,
It is preferable to use together a thermally conductive filler having excellent electric insulation such as silicon carbide and aluminum hydroxide.

A magnetic field is applied to the above-mentioned polymer composition from the outside to orient the graphitized carbon fibers in the magnetic field, and the polymer composition is cured or solidified into a sheet in the oriented state to obtain thermal conductivity. A sheet is obtained.

Here, in the production method of the present invention, the viscosity of the polymer matrix material when the graphitized carbon fibers are oriented in the magnetic field is 0.025 to 100 (Pa · s).
Alternatively, the viscosity of the polymer composition when the graphitized carbon fiber is oriented in the magnetic field is required to be 0.15 to 120 (Pa · s). By setting the viscosity of the polymer matrix material or the polymer composition in the magnetic field orientation of the graphitized carbon fiber within the above range, it becomes easy to control the magnetic field orientation of the graphitized carbon fiber in the polymer matrix material and The carbon fibers can be highly oriented in a certain direction, and a heat conductive sheet having high heat conductivity can be realized.

On the other hand, when the viscosity of the polymer matrix material in this magnetic field orientation is less than 0.025 (Pa · s) or the viscosity of the polymer composition portion is less than 0.15 (Pa · s), Due to vibration and heat flow of the polymer matrix material, the orientation of the graphitized carbon fiber becomes unstable,
It becomes impossible to stably produce the heat conductive sheet having high heat conductivity by highly orienting the graphitized carbon fiber. In addition, the graphitized carbon fibers in the polymer matrix material settle due to their own weight, and the dispersed state of the graphitized carbon fibers in the polymer matrix material becomes non-uniform, resulting in a heat conductive sheet having high thermal conductivity. Can no longer be manufactured stably.

On the other hand, the viscosity of the polymer matrix material in this magnetic field orientation is larger than 100 (Pa · s),
Alternatively, when the viscosity of the polymer composition is higher than 120 (Pa · s), the fluidity of the polymer matrix material is almost lost, the orientation of the graphitized carbon fibers becomes difficult, and the heat conductive sheet having high heat conductivity. Can no longer be manufactured stably. In addition, the flowability of the polymer matrix material is extremely poor, which not only deteriorates the processability, but also a large amount of air bubbles are mixed in when the graphitized carbon fiber is mixed, and it takes time to remove the air bubbles. Sex deteriorates.

The viscosity of the above-mentioned polymer matrix material or polymer composition is not particularly limited, and various known methods may be used. Depending on the type of polymer matrix material used and its temperature conditions,
For example, by adding a curing agent or a crosslinking agent,
It is possible to increase the viscosity of the polymer matrix material or polymer composition during magnetic field orientation. Further, the viscosity of the polymer matrix material or polymer composition can be lowered by adding a volatile organic solvent, a low-viscosity softening agent or a reactive plasticizer. Furthermore, the viscosity of the polymer matrix material or polymer composition can be adjusted by controlling the temperature such as heating. In particular,
When a thermoplastic material is used as the polymer matrix material, it is effective because temperature control is easy. A polymer matrix material having a viscosity in the magnetic field orientation within the above viscosity range may be selected in advance and used.

The external magnetic field for orienting the graphitized carbon fibers in the magnetic field preferably has a magnetic flux density of 1 to 15 Tesla, more preferably 3 to 10 Tesla. When the magnetic flux density is less than 1 tesla, the magnetic field is weak and the magnetic field orientation of the graphitized carbon fiber is insufficient, so that the graphitized carbon fiber cannot be highly oriented in a certain direction, and the resulting heat conductive sheet is The thermal conductivity becomes poor. When the magnetic flux density exceeds 15 tesla, it becomes easy to highly orient the graphitized carbon fibers in a certain direction, but the magnetic field generator and its running cost are expensive and the industrial advantage is lost.

The method of processing the polymer composition into a sheet is not particularly limited, and a known method is used. For example, when the polymer composition is a fluid liquid, it can be processed by a method using coating, printing, dispenser, potting, roll, or the like. When the polymer composition is a thermoplastic material that is solid at room temperature and melts into a liquid when heated, it can be processed by a method such as an injection molding method using a mold or a pressure molding method.

Next, an application example of the above-mentioned heat conductive sheet will be described. This heat conductive sheet is provided between a heat generating member such as a semiconductor element, a power source or a light source, and a heat radiating member such as a printed wiring board, a heat radiating plate, a heat radiating rubber sheet, a semiconductor package component, a heat sink, a heat spreader or a case. It is used by interposing, etc., and has the function of effectively dissipating the heat generated by the heat generating member to the outside.

In the example shown in FIG. 1, the printed wiring board 11
The semiconductor element 12 (ball grid array type semiconductor package) is mounted on the semiconductor element 12 and the radiator 1.
A heat conductive sheet 14 is interposed between the sheet 3 and the sheet 3.

In the example shown in FIG. 2, the printed wiring board 11
A semiconductor element 12 (chip size type semiconductor package) is mounted thereon, and a heat conductive sheet 14 is interposed between the printed wiring board 11 and the semiconductor element 12.

In the example shown in FIG. 3, the printed wiring board 11 is used.
A semiconductor element 12 (pin grid array type semiconductor package) is mounted on the semiconductor element 12, and a heat conductive sheet 14 is interposed between the semiconductor element 12 and a heat sink 15.

In the example shown in FIG. 4, the printed wiring board 11
A plurality of mounting components 16 are mounted on the top, and the heat conductive sheet 14 is interposed between the plurality of mounting components 16 and the housing 17.

As described in detail above, according to this embodiment, the following operational effects are exhibited. The viscosity of the polymer matrix material when the graphitized carbon fiber is oriented in the magnetic field is 0.025 to 100 (Pa · s), or the viscosity of the polymer composition is 0.15 to 120.
By setting (Pa · s), it becomes easy to control the magnetic field orientation of the graphitized carbon fibers in the polymer matrix material, and the graphitized carbon fibers can be highly oriented. Therefore, by taking advantage of the high thermal conductivity of the graphitized carbon fiber in the fiber axis direction, it is possible to easily and inexpensively manufacture a thermally conductive sheet with dramatically improved thermal conductivity. Therefore, it is possible to easily and inexpensively manufacture a heat conductive sheet having high thermal conductivity capable of dissipating a large amount of heat generated from components such as a semiconductor element used in electric equipment, a power source, and a light source, which has high productivity. A manufacturing method can be realized.

By using a thermoplastic material as the polymer matrix material, it is possible to easily control the viscosity of the polymer matrix material or the polymer composition by controlling the temperature such as heating. Therefore, it becomes easy to control the magnetic field orientation of the graphitized carbon fibers in the polymer matrix material, and the graphitized carbon fibers in the polymer matrix material are highly oriented so that the thermal conductivity is dramatically improved. Can be manufactured easily and at low cost. That is, it is possible to realize a highly productive manufacturing method capable of easily and inexpensively manufacturing a heat conductive sheet having excellent heat conductivity.

[0038]

EXAMPLES The above embodiments will be described in more detail with reference to examples and comparative examples, but these do not limit the scope of the present invention.

(Examples 1 to 4) Addition type liquid silicone rubber as a polymer matrix material (viscosity at room temperature: 0.025 (Pa · s), 0.1 (Pa · s), 1
(Pa · s), 100 (Pa · s)) 100 parts by weight,
A polymer composition was prepared by mixing and dispersing 100 parts by weight of graphitized carbon fiber surface-treated with a silane coupling agent, 40 parts by weight of aluminum oxide powder, and 20 parts by weight of aluminum hydroxide powder. The viscosity of the obtained polymer composition at room temperature is 0.175 (Pa · s) and 0.665, respectively.
(Pa · s), 1.56 (Pa · s), 100.84
(Pa · s). Then, a magnetic field was applied to the obtained polymer composition at room temperature to orient the graphitized carbon fibers in a certain direction and then thermoset to prepare a heat conductive sheet having a thickness of 2 mm.

Comparative Examples 1 and 2 Addition type liquid silicone rubber (viscosity at room temperature: 0.02 (Pa · s), 120 (Pa · s)) as a polymer matrix material 10
0 parts by weight, 100 parts by weight of graphitized carbon fiber surface-treated with a silane coupling agent, aluminum oxide powder 4
A polymer composition was prepared by mixing and dispersing 0 part by weight and 20 parts by weight of aluminum hydroxide powder. The viscosity of the obtained polymer composition at room temperature is 0.136 (Pa · s),
It was 121.64 (Pa * s). Then, a magnetic field is applied to the obtained polymer composition at room temperature to orient the graphitized carbon fibers in a certain direction and then thermoset to have a thickness of 2 mm.
The heat conductive sheet of was produced.

Table 1 shows the results of evaluating the orientation of the graphitized carbon fibers in the heat conductive sheets prepared in Examples 1 to 4 and Comparative Examples 1 and 2. The orientation of the graphitized carbon fiber was evaluated as ⊚ when it was very good, ◯ when it was good, and × when it was in a poor alignment state. Also,
Table 1 shows the results of measuring the thermal conductivity and the thermal resistance of each thermally conductive sheet in the sheet thickness direction.

[0042]

[Table 1] Examples 5 to 6 Melt of solid paraffin as a polymer matrix material (viscosity in molten state: 0.025
(Pa · s), 0.1 (Pa · s)) 100 parts by weight,
A polymer composition was prepared by mixing and dispersing 100 parts by weight of graphitized carbon fiber surface-treated with a silane coupling agent, 40 parts by weight of aluminum oxide powder, and 20 parts by weight of aluminum hydroxide powder. The viscosity of the obtained polymer composition in the molten state was 0.154 (Pa · s) and 0.682, respectively.
(Pa · s). Then, a magnetic field was applied to this molten polymer composition to orient the graphitized carbon fibers in a fixed direction and then cooled and solidified to prepare a heat conductive sheet having a thickness of 2 mm.

Comparative Example 3 Melt of solid paraffin as polymer matrix material (viscosity in molten state: 0.02)
(Pa · s)) 100 parts by weight, 100 parts by weight of graphitized carbon fiber surface-treated with a silane coupling agent, 40 parts by weight of aluminum oxide powder, and 20 parts by weight of aluminum hydroxide powder are mixed and dispersed to give a polymer. A composition was prepared. The viscosity of the obtained molten polymer composition was 0.09 (P
a * s). Then, a magnetic field was applied to the polymer composition in the molten state to orient the graphitized carbon fibers in a fixed direction and then cooled and solidified to prepare a heat conductive sheet having a thickness of 2 mm.

Table 2 shows the results of evaluating the orientation of the graphitized carbon fibers in the heat conductive sheets prepared in Examples 5 and 6 and Comparative Example 3 above. The orientation of the graphitized carbon fiber was evaluated as ⊚ when it was very good, ◯ when it was good, and × when it was in a poor alignment state. Table 2 shows the results of measuring the thermal conductivity and the thermal resistance of each thermally conductive sheet in the sheet thickness direction.

[0045]

[Table 2] (Examples 7 to 8) Melt of thermoplastic resin as polymer matrix material (viscosity in molten state: 80 (Pa
s), 97.5 (Pa · s)) 100 parts by weight, and graphitized carbon fiber 10 surface-treated with a silane coupling agent
0 parts by weight, 40 parts by weight of aluminum oxide powder, and 20 parts by weight of aluminum hydroxide powder were mixed and dispersed to prepare a polymer composition. The viscosities of the obtained polymer compositions in a molten state are 102.5 (Pa · s) and 115.5 (P), respectively.
a * s). Then, a magnetic field was applied to the polymer composition in the molten state to orient the graphitized carbon fibers in a fixed direction and then cooled and solidified to prepare a heat conductive sheet having a thickness of 2 mm.

Comparative Example 4 Melt of thermoplastic resin as polymer matrix material (viscosity in molten state: 160 (P
a) s)) 100 parts by weight, 100 parts by weight of graphitized carbon fiber surface-treated with a silane coupling agent, 40 parts by weight of aluminum oxide powder, 20 parts of aluminum hydroxide powder
A polymer composition was prepared by mixing and dispersing parts by weight. The viscosity of the obtained molten polymer composition is 195 (Pa.
s). Then, a magnetic field was applied to the polymer composition in the molten state to orient the graphitized carbon fibers in a fixed direction and then cooled and solidified to prepare a heat conductive sheet having a thickness of 2 mm.

Table 3 shows the results of evaluation of the orientation of the graphitized carbon fibers in the heat conductive sheets produced in Examples 7 and 8 and Comparative Example 4 above. The orientation of the graphitized carbon fiber was evaluated as ⊚ when it was very good, ◯ when it was good, and × when it was in a poor alignment state. Table 3 shows the results of measuring the thermal conductivity and the thermal resistance of each thermally conductive sheet in the sheet thickness direction.

[0048]

[Table 3] As shown in Tables 1 to 3, in each of the heat conductive sheets of Examples 1 to 8, the viscosity of the polymer matrix material is 0.025 to 100 (Pa · s), and the viscosity of the polymer composition. Is a graphitized carbon fiber magnetic field oriented under the condition of 0.15 to 120 (Pa · s). Examples 1 to 1
In each of the heat conductive sheets of Example 8, the graphitized carbon fibers had a good orientation state, and high heat conductivity was obtained.

On the other hand, in each of the heat conductive sheets of Comparative Examples 1 to 4, the polymer matrix material has a viscosity of 0.0.
It is a magnetic field oriented graphitized carbon fiber under conditions where the viscosity of the polymer composition is outside the range of 25 to 100 (Pa · s) and the viscosity of the polymer composition is outside the range of 0.15 to 120 (Pa · s). is there.
In each of the heat conductive sheets of Comparative Examples 1 to 4, the orientation of the graphitized carbon fiber was poor, and high heat conductivity could not be obtained.

(Supplementary Notes) Hereinafter, the technical ideas grasped from the above-described embodiments and examples will be described together with their operational effects.

The method for producing a heat conductive sheet according to claim 1 or 2, wherein the polymer matrix material is liquid silicone rubber. Liquid silicone rubber has a viscosity at room temperature of 0.025 to 100 (Pa
・ Since the grade of s) is easily available in the market, by pre-selecting and using a liquid silicone rubber whose viscosity in the magnetic field orientation is in the above viscosity range,
There is no need to perform viscosity adjustment again when the graphitized carbon fiber is oriented in the magnetic field. Therefore, by taking advantage of the high thermal conductivity of the graphitized carbon fiber in the fiber axis direction, a thermal conductive sheet with dramatically improved thermal conductivity can be produced easily and at low cost. It is possible to realize a highly productive manufacturing method capable of manufacturing a heat conductive sheet having conductivity simply and at low cost.

The heat conduction according to claim 1 or 2, wherein the polymer matrix material is a thermoplastic material, and the viscosity of the polymer matrix material or the polymer composition is adjusted by controlling the temperature. Of manufacturing a flexible sheet.
By doing so, the viscosity of the polymer matrix material or polymer composition can be easily adjusted, and the magnetic field orientation control of the graphitized carbon fibers in the polymer matrix material becomes easy. Therefore, the graphitized carbon fiber can be highly oriented, and the high thermal conductivity in the fiber axis direction of the graphitized carbon fiber can be utilized to easily and inexpensively produce a thermally conductive sheet with dramatically improved thermal conductivity. Can be manufactured in. That is, it is possible to realize a highly productive manufacturing method capable of easily and inexpensively manufacturing a heat conductive sheet having excellent heat conductivity.

[0053]

As described in detail above, according to the method for producing a heat conductive sheet of the present invention, the viscosity of the polymer matrix material when the graphitized carbon fibers are oriented in the magnetic field is 0.025.
To 100 (Pa · s) or the viscosity of the polymer composition is 0.15 to 120 (Pa · s), the magnetic field orientation control of the graphitized carbon fibers in the polymer matrix material can be controlled. It becomes easy and the graphitized carbon fiber can be highly oriented. Therefore, by taking advantage of the high thermal conductivity in the fiber axis direction of the graphitized carbon fiber, a thermal conductive sheet with dramatically improved thermal conductivity can be realized easily and at low cost. It is possible to realize a highly productive manufacturing method capable of manufacturing a heat conductive sheet having conductivity simply and at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an application example of a heat conductive sheet of the present invention.

FIG. 2 is a cross-sectional view showing another application example of the heat conductive sheet of the present invention.

FIG. 3 is a cross-sectional view showing another application example of the heat conductive sheet of the present invention.

FIG. 4 is a cross-sectional view showing another application example of the heat conductive sheet of the present invention.

[Explanation of symbols]

11 ... Printed wiring board, 12 ... Semiconductor elements 12, 13
... radiator, 14 ... thermal conductive sheet, 15 ... heat sink, 16 ... mounted parts, 17 ... housing.

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) C08K 7/06 C08K 7/06 C08L 101/00 C08L 101/00 // B29K 7:00 B29K 7:00 105: 14 105 : 14 F term (reference) 4F071 AA01 AA02 AA03 AA10 AA11 AA12 AA13 AA14 AA15 AA20 AA21 AA22 AA24 AA25 AA26 AA AA 32 AA33 AA4 A45 A51 A51 A51 A51 A51 A51 A51 A51 AA AF45 AH12 AH16 BB13 BC01 4F204 AA33C AA45 AB18 AB25 AD02 AD16 AG01 AH33 AH36 AM29 AR17 EA03 EA04 EB01 EB11 EE06 4J002 AC011 AC031 AC061 AC071 AC081 AC091 BB021 BB051 BB061 BB111 BB151 BB171 BB181 BB241 BB271 BC021 BC061 BD031 BD101 BD121 BD141 BD151 BE021 BF021 BG011 BG041 BG101 BH001 BN151 BP011 CB001 CC031 CD001 CF061 CF071 CF101 CF171 CF211 CG001 CH071 CH091 CJ001 CK021 CK031 CK041 CL011 CL031 CL071 CM041 CN011 CN031 CP031 DA026 FA046 FD110 FD116 GQ00

Claims (3)

[Claims] 1. A magnetic composition is applied to a polymer composition containing graphitized carbon fibers in a polymer matrix material to orient the graphitized carbon fibers in a magnetic field, and then the polymer composition is formed into a sheet. A method for producing a thermally conductive sheet that cures or solidifies, wherein the polymer matrix material has a viscosity of 0.025 to 100 (Pa · s) when the graphitized carbon fibers are oriented in a magnetic field.
And a method for manufacturing a heat conductive sheet. 2. A polymer composition containing a graphitized carbon fiber in a polymer matrix material is applied with a magnetic field to orient the graphitized carbon fiber in a magnetic field, and then the polymer composition is formed into a sheet. A method for producing a thermally conductive sheet that cures or solidifies, characterized in that the viscosity of the polymer composition during magnetic field orientation of the graphitized carbon fibers is 0.15 to 120 (Pa · s). Method for manufacturing heat conductive sheet. 3. The method for producing a heat conductive sheet according to claim 1, wherein the polymer matrix material is a thermoplastic material.