JP2009149831A - Thermoconductive sheet, manufacturing method thereof, and heat-radiating device using thermoconductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoconductive sheet which has both the high thermoconductivity and the high flexibility; a manufacturing method which gives the thermoconductive sheet profitably and reliably in the view points of the productivity, the cost aspect and the energy efficiency; and a heat-radiating device having a high heat-radiating capacity. <P>SOLUTION: The thermoconductive sheet contains a composition containing graphite particles (A) that are of a flake form, an ellipsoidal form or a rod form and that the six-membered ring planes in a crystal are orientated to the surface direction of the flake, to a major axis direction of the ellipsoid or to the major direction of the rod, and containing an organic high molecular compound (B) having a Tg of 0°C or lower, and is formed in such a way that the graphite particles (A) have the surface direction of the flakes, the major axis direction of the ellipsoid or the major axis direction of the rod orientated to the thickness direction inside the sheet, and the graphite particles (A) in the tip parts are folded, at the surface part of the one side or both sides of the sheet, at an angle of 60-90°as an axis of the sheet thickness direction toward the direction along the surface of the sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat conductive sheet, a manufacturing method thereof, and a heat dissipation device using the heat conductive sheet.

  In recent years, the density of wiring and the mounting density of electronic components on multilayer wiring boards and semiconductor packages have increased, and the amount of heat generated per unit area has increased due to higher integration of semiconductor elements. There is a desire to improve.

  A heat dissipation device that dissipates heat by sandwiching a heat conductive grease or a heat conductive sheet between a heat generator such as a semiconductor package and a heat radiator such as aluminum or copper is generally used in a simple manner. The heat conduction sheet is superior to the heat conduction grease in assembling the heat dissipation device. In order to improve heat dissipation, the heat conductive sheet is required to have high heat conductivity, but the heat conductivity of the conventional heat conductive sheet is not always sufficient.

  Therefore, for the purpose of further improving the heat conductivity of the heat conductive sheet, various heat conductive composite compositions and molded products thereof, in which a matrix material is mixed with graphite powder having a large heat conductivity in one direction, are provided. Proposed.

  For example, Patent Document 1 discloses a thermally conductive resin molded product in which graphite powder is filled in a thermoplastic resin, and Patent Document 2 discloses a polyester resin composition containing graphite, carbon black, and the like.

  Patent Document 3 contains a rubber composition in which artificial graphite having a particle size of 1 to 20 μm is blended, and Patent Document 4 has a composition in which spherical graphite powder having a crystal plane spacing of 0.33 to 0.34 nm is blended in silicone rubber. Things are disclosed.

  Further, Patent Document 5 discloses a molded body containing carbon fibers that are vertically aligned with respect to the cutting direction and an elastic body for maintaining the shape, and Patent Document 6 is inclined with respect to a direction perpendicular to the cutting surface. A polymer composition containing a thermally conductive fiber such as graphitized carbon fiber is disclosed.

  Furthermore, Patent Document 7 discloses a thermally conductive molded body in which the c-axis in the crystal structure of the graphite powder in the molded body is oriented in a direction orthogonal to the thermal conduction direction, and a method for manufacturing the same.

  On the other hand, the heat conductive sheet has the advantage that the workability when assembling the heat dissipation device is simple as described above. As a way to further utilize this advantage, followability to special shapes such as irregularities and curved surfaces, stress There is a growing need for mitigation and other functions.

  For example, in heat dissipation from a large area such as a display panel, the heat conduction sheet has functions such as the ability to follow the shape of the surface of the heat generator and the heat sink, such as distortion and unevenness, and thermal stress relaxation caused by the difference in coefficient of thermal expansion. In addition to high thermal conductivity that can transfer heat even to a somewhat thick film, high flexibility has been required.

However, a thermal conductive sheet that can achieve both such flexibility and thermal conductivity at a high level has not yet been obtained.
Even in the case of a molded body in which a specific graphite powder is randomly dispersed in the molded body as described above, the thermal conductivity is still insufficient for the advanced thermal conductivity characteristics that are actually required. .

  In addition, a molded body in which carbon fibers are oriented perpendicular to the cut surface does not necessarily have sufficient consideration for flexibility, and the contact property of the fiber end exposed on the surface to the adherend is not always sufficient. The contact resistance is not sufficiently lowered, and lacks certainty in obtaining high thermal conductivity.

  Furthermore, in the method for producing a thermally conductive molded body in which the c-axis in the crystal structure of the graphite powder in the molded body is oriented in a direction orthogonal to the heat conduction direction, the graphite particles are not reliably exposed on the surface, Since the contact property with the adherend is not always sufficient, there is no certainty in obtaining high thermal conductivity, and further, considerations such as productivity, cost and energy efficiency are not sufficient.

JP-A-62-131033 Japanese Patent Laid-Open No. 04-246456 JP 05-247268 A JP-A-10-298433 JP 2001-250894 A JP 2002-088171 A JP 2003-321554 A

  The present invention relates to a heat conductive sheet having both high thermal conductivity and high flexibility, a method for producing the heat conductive sheet advantageously and reliably in terms of productivity, cost and energy efficiency, and high heat radiation heat capacity. An object of the present invention is to provide a heat dissipation device having

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have high thermal conductivity by orienting the graphite particles in the sheet thickness direction, and in the graphite particles on the sheet surface, the tips of the graphite particles It was found that the graphite particles exposed on the surface are excellent in contact with the adherend by adjusting the portion to be bent along the sheet surface.
That is, the present invention is as follows.
(1) Graphite particles (A) that are scale-like, elliptical, or rod-shaped, and whose six-membered ring faces in the crystal are oriented in the plane direction of the scale, the major axis direction of the ellipsoid, or the major axis direction of the rod; A heat conductive sheet comprising a composition containing an organic polymer compound (B) having a Tg of 0 ° C. or less,
The surface direction of the scale of the graphite particles (A), the major axis direction of the ellipsoid or the major axis direction of the rod is oriented in the thickness direction inside the sheet, and the graphite particles ( A heat conductive sheet in which the tip portion of A) is bent at an angle of 60 to 90 degrees with the thickness direction of the sheet as an axis in a direction along the surface of the sheet.

(2) The heat conductive sheet according to the above (1), wherein the number of graphite particles (A) bent at the surface portion of the sheet is 5 to 20 per 500 μm in the transverse direction in the cross section in the thickness direction of the sheet. .
(3) The heat conductive sheet according to (1) or (2), wherein the bending point of the graphite particles (A) bent at the surface portion of the sheet is located within 10% of the sheet thickness from the surface of the sheet.

(4) The length of the bent portion of the graphite particles (A) bent at the surface portion of the sheet is 5 to 20% of the sheet thickness, as described in any one of (1) to (3) above. Thermal conductive sheet.
(5) In the composition, the graphite particles (A) are blended in an amount of 10 to 50% by volume, and the organic polymer compound (B) is blended in an amount of 10 to 50% by volume. The heat conductive sheet as described in any one of 4).
(6) Graphite particles (A) that are scale-like, oval or rod-shaped, and whose six-membered ring surface in the crystal is oriented in the plane direction of the scale, the major axis direction of the ellipse, or the major axis direction of the rod; A composition containing an organic polymer compound (B) having a Tg of 0 ° C. or less is pressed at a pressure of 5 to 10 MPa in a direction parallel to the orientation direction of the graphite particles (A) in the composition. Producing a primary sheet in which the graphite particles (A) are oriented in a direction substantially parallel to the surface;
Laminating the primary sheet to obtain a molded body,
While pressing the molded body at a pressure of 0.01 to 0.5 MPa, the sheet is sliced at an angle of 0 to 30 degrees with respect to the normal from the primary sheet surface to obtain a heat conductive sheet, and the surface on one or both sides of the heat conductive sheet A method for producing a heat conductive sheet, characterized in that the tip portion of the graphite particles (A) is bent at an angle of 60 to 90 degrees about the thickness direction of the sheet in a direction along the surface of the sheet.

(7) Graphite particles (A) that are scale-like, elliptical, or rod-shaped, and in which the six-membered ring surface in the crystal is oriented in the plane direction of the scale, the major axis direction of the ellipse, or the major axis direction of the rod; A composition containing an organic polymer compound (B) having a Tg of 0 ° C. or less is pressed at a pressure of 5 to 10 MPa in a direction parallel to the orientation direction of the graphite particles (A) in the composition. Producing a primary sheet in which the graphite particles (A) are oriented in a direction substantially parallel to the surface;
The primary sheet is wound around the orientation direction of the graphite particles (A) to obtain a molded body,
The pressed body is sliced at an angle of 0 degree to 30 degrees with respect to the normal line coming out from the primary sheet surface while being pressed at a pressure of 0.01 to 0.5 MPa to obtain a heat conductive sheet, on one or both sides of the heat conductive sheet A method for producing a heat conductive sheet, characterized in that the tip portion of the graphite particles (A) is bent at an angle of 60 to 90 degrees about the thickness direction of the sheet in a direction along the surface of the sheet at the surface portion.

(8) The slicing of the molded body is performed using a slicing member having a smooth board surface having a slit and a blade part protruding from the slit part,
The said blade part is a manufacturing method of the heat conductive sheet as described in said (6) or (7) whose protrusion length from the said slit part can be adjusted according to the desired thickness of the said heat conductive sheet.

(9) The method for manufacturing a heat conductive sheet according to (8), wherein the slice member is a plane or a slicer.
(10) The manufacturing method of the heat conductive sheet as described in any one of said (6)-(9) which slices the said molded object in the temperature range of -20-10 degreeC.
(11) Heat obtained by the method for producing a heat conductive sheet according to any one of (1) to (5) or the heat conductive sheet according to any one of (6) to (10). A heat dissipation device in which a conductive sheet is interposed between a heating element and a heat dissipation element.

  In the heat conductive sheet according to (1), the tip of the graphite particles (A) is bent at the surface portion of the sheet, and the exposed area of the graphite particles (A) on the surface of the sheet is increased, so that the contact property to the adherend is increased. Therefore, it has high thermal conductivity and high flexibility, and is suitable for heat dissipation applications.

Moreover, in addition to the effect of the invention of the said (1), the heat conductive sheet in any one of said (2)-(5) can achieve still higher heat conductivity.
The method for producing a heat conductive sheet according to the above (6) or (7) is advantageous in that the heat conductive sheet having both high heat conductivity and high flexibility is advantageous in terms of productivity, cost, and energy efficiency. Can be manufactured reliably.

In addition to the effects of the invention described in (6) or (7) above, the method for producing a heat conductive sheet according to any one of (8) to (10) described above, wherein the graphite particles (A) are the surface of the sheet. Since it can manufacture so that it may bend in a part reliably, the heat conductive sheet with high heat conductivity can be manufactured.
Furthermore, the heat dissipation device described in (11) has a high heat dissipation capability.

The present invention is described in detail below.
The heat conductive sheet of the present invention has a scaly shape, an elliptical shape, or a rod shape, and a graphite particle in which the six-membered ring surface in the crystal is oriented in the surface direction of the scale, the major axis direction of the ellipse, or the major axis direction of the rod. A composition containing (A) and an organic polymer compound (B) having a Tg of 0 ° C. or less, and the scale direction of the graphite particles (A), the long axis direction of the ellipsoid, or the length of the rod The axial direction is oriented in the thickness direction inside the sheet, and at the surface part on one side or both sides of the sheet, the tip part of the graphite particles (A) is oriented along the sheet thickness direction in the direction along the sheet surface, It is bent at an angle of 60 to 90 degrees.

  In the present invention, the graphite particles (A) have a scaly shape, an elliptical shape, or a rod-like shape, and a scaly shape is particularly preferable. When the shape of the graphite particles (A) is spherical or indefinite, the thermal conductivity is inferior, and when it is fibrous, it is difficult to form into a sheet, so that the productivity tends to be inferior. The 6-membered ring surface in the crystal of graphite particles (A) is oriented in the scale direction, the long axis direction of the ellipse, or the long axis direction of the rod. This can be confirmed by X-ray diffraction measurement.

Specifically, the following method is used for confirmation. First, a measurement sample sheet is prepared in which the surface direction of the scale of graphite particles, the long axis direction of the ellipsoid, or the long axis direction of the rod is oriented substantially parallel to the surface direction of the sheet or film. As a specific method for preparing the measurement sample sheet, a mixture of 10% by volume or more of graphite particles and a resin is formed into a sheet. As the “resin” used here, a resin corresponding to the organic polymer compound (B) can be used, but any material that does not show a peak that interferes with X-ray diffraction, such as an amorphous resin, may be used. If it can be made, it can be used even if it is not a resin. This sheet is pressed so that it becomes 1/10 or less of the original thickness, and the pressed sheets are laminated. The operation of further crushing this laminate to 1/10 or less is repeated three or more times. In the sample sheet for measurement prepared by this operation, the surface direction of the graphite particle scale, the major axis direction of the ellipse, or the major axis direction of the rod is oriented substantially parallel to the surface direction of the sheet or film. Become. When the X-ray diffraction measurement is performed on the surface of the measurement sample sheet prepared as described above, the peak height corresponding to the (110) plane of graphite appearing near 2θ = 77 ° appears near 2θ = 27 °. The value divided by the height of the peak corresponding to the (002) plane of graphite is 0 to 0.02.
Accordingly, in the present invention, “the 6-membered ring surface in the crystal is oriented in the plane direction of the scale, the long axis direction of the ellipse or the long axis direction of the rod” means graphite particles, organic polymer compounds, etc. X-ray diffraction measurement is performed on the surface of the heat conductive sheet composition of the above, and the height of the peak corresponding to the (110) plane of graphite appearing in the vicinity of 2θ = 77 ° appears in the vicinity of 2θ = 27 °. A state in which the value divided by the height of the peak corresponding to the (002) plane of graphite is 0 to 0.02.

  Examples of the graphite particles (A) used in the present invention include flaky graphite powder, artificial graphite powder, exfoliated graphite powder, acid-treated graphite powder, expanded graphite powder, carbon fiber flakes, and other scaly, oval or rod-like particles. Graphite particles can be used. In particular, those that easily become scaly graphite particles when mixed with the organic polymer compound (B) are preferred. Specifically, the flaky graphite particles of the flaky graphite powder, the exfoliated graphite powder, and the expanded graphite powder are more preferable because they are easy to orient, maintain inter-particle contact, and easily obtain high thermal conductivity.

The average value of the major axis of the graphite particles (A) is not particularly limited, but is preferably 0.1 to 5 mm, more preferably 0.2 to 3 mm, and particularly preferably 0.2 to 1 mm from the viewpoint of improving thermal conductivity. It is.
The sheet thickness is preferably 1 to 5 times the average value of the major axis of the graphite particles (A), more preferably 1 to 3 times.
In the present invention, the “average value of the major axis” means that the cross section in the thickness direction of each side obtained by cutting the heat conductive sheet into a regular octagon is observed using an SEM (scanning electron microscope), and the cross section of any one side. , The major axis is measured from the direction seen for any 50 graphite particles, and the average value is obtained.

Although content in particular of a graphite particle (A) is not restrict | limited, It is preferable that it is 10-50 volume% of the whole composition volume, and it is more preferable that it is 30-45 volume%. When the content of the graphite particles (A) is less than 10% by volume, the thermal conductivity tends to decrease, and when it exceeds 50% by volume, sufficient flexibility and adhesion tend to be difficult to obtain. is there. In addition, content (volume%) of the graphite particle (A) in this specification is the value calculated | required by following Formula.
Content of graphite particles (A) (volume%) =
(Aw / Ad) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) +...) × 100
Aw: mass composition of graphite particles (A) (% by weight)
Bw: mass composition (% by weight) of polymer compound (B)
Cw: mass composition (% by weight) of other optional component (C)
Ad: Specific gravity of graphite particles (A) (In the present invention, Ad is calculated as 2.25)
Bd: Specific gravity of polymer compound (B) Cd: Specific gravity of other optional component (C)

The organic polymer compound (B) used in the present invention has a Tg (glass transition temperature) of 0 ° C. or lower, preferably −100 to 0 ° C., more preferably −70 to −30 ° C. When the Tg exceeds 0 ° C., the flexibility is inferior, and the adhesion to the heating element and the radiator tends to be poor.
Moreover, when Tg exceeds 0 degreeC, since it is inferior to a softness | flexibility, in the heat conductive sheet, the front-end | tip part of a graphite particle (A) is 60-90 centering on the thickness direction of a sheet | seat in the direction along the surface of a sheet | seat. It becomes difficult to bend at an angle of degrees.

  The organic polymer compound (B) used in the present invention is not particularly limited as long as Tg is 0 ° C. or lower. For example, poly (main component of butyl acrylate, 2-ethylhexyl acrylate, etc.) (Meth) acrylic acid ester polymer compound (so-called acrylic rubber), polymer compound having polydimethylsiloxane structure in main structure (so-called silicone resin), polymer compound having polyisoprene structure in main structure (so-called isoprene rubber, natural Rubber), polymer compounds containing chloroprene as a main raw material component (so-called chloroprene rubber), polymer compounds having a polybutadiene structure as a main structure (so-called butadiene rubber), etc., and flexible organic polymers generally referred to as “rubber” Compounds.

Among these, poly (meth) acrylic acid ester-based polymer compounds mainly composed of butyl acrylate, 2-ethylhexyl acrylate, etc. are easy to obtain high flexibility and excellent in chemical stability and workability. It is preferable because it is easy to control the tackiness and is relatively inexpensive.
Specific examples of the organic polymer compound (B) having a Tg of 0 ° C. or lower include butyl acrylate / ethyl acrylate / 2-hydroxyethyl methacrylate (trade name: HTR-811DR), Nagase manufactured by Nagase ChemteX Corporation. Examples include butyl acrylate / acrylonitrile / acrylic acid (trade name: HTR-280DR) manufactured by Chemtex Corporation.
Although content in particular of an organic polymer compound (B) is not restrict | limited, Preferably it is 10-50 volume% with respect to the composition whole volume, More preferably, it is 30-50 volume%.
The heat conductive sheet of this invention can contain a flame retardant. It does not specifically limit as a flame retardant, For example, a red phosphorus flame retardant and a phosphate ester flame retardant can be contained.
In addition, the heat conductive sheet of the present invention may further include a toughness improver such as urethane acrylate; a hygroscopic agent such as calcium oxide or magnesium oxide; an adhesive force such as a silane coupling agent, a titanium coupling agent, or an acid anhydride. An improvement agent; a wetting improvement agent such as a nonionic surfactant or a fluorine-based surfactant; an antifoaming agent such as silicone oil; an ion trapping agent such as an inorganic ion exchanger; or the like can be appropriately added.

  In the present invention, the surface direction of the scale, the major axis direction of the ellipsoid or the major axis direction of the rod is “oriented in the thickness direction inside the sheet” means that the heat conduction sheet is first cut into a regular octagon in the thickness direction of each side. The cross section is observed using a fluorescence microscope, and with respect to any one of the cross sections, an angle with respect to the heat conduction sheet surface in the major axis direction of the graphite particles from the direction seen for any 50 graphite particles (at least 90 degrees) In this case, a complementary angle is employed) and the average value is in the range of 60 to 90 degrees.

Further, in the present invention, “the tip portion of the graphite particle (A) is bent” means that the cross section in the thickness direction of each side obtained by cutting the heat conductive sheet into a regular octagon is observed using a fluorescence microscope, Regarding an arbitrary 30 graphite particles (A) whose front end portions are bent at the surface portions on both sides of the sheet with respect to the cross section of one side, an angle (90 with respect to the thickness direction of the sheet) in the direction along the surface of the sheet When the angle is greater than or equal to a degree, a complementary angle is employed), and the angle is in a range of 60 to 90 degrees. The bent portion is not necessarily a “corner”, and may be curved.
FIG. 1 specifically shows a state where the tip portion of the graphite particle (A) is bent. As shown in FIG. 1, it can be confirmed that the graphite particles are bent at the sheet surface portion.

  In the heat conductive sheet of the present invention, the graphite particles (A) oriented inside the sheet contribute to high heat conductivity inside the sheet, and the tip portion of the graphite particles (A) bends at the above angle, so that the adherence to the adherend is ensured. As a result of contributing to proper contact, good thermal conductivity is obtained as a whole.

In the heat conductive sheet of the present invention, the number of graphite particles (A) bent at the surface portion of the sheet is 5 to 20, preferably 10 to 20 per 500 μm in the transverse direction in the cross section in the thickness direction of the sheet. More preferably, it is 15-20. From the viewpoint of improving thermal conductivity, the larger the number of the graphite particles (A), the better. When the number of the graphite particles (A) is less than 5, there is a tendency that sufficient thermal conductivity cannot be obtained.
The number of graphite particles (A) bent at the surface portion of the sheet is measured by observing a cross section in the thickness direction of each side obtained by cutting the heat conductive sheet into a regular octagon using a fluorescence microscope. Specifically, one fluorescence micrograph is taken for any five locations (total 5) in which a transverse length of 500 μm is taken in the cross section of any one side in the thickness direction of each side obtained by cutting the sheet into a regular octagon. The total number of graphite particles (A) in which the tip portion is bent at the above angle at the surface portion on both sides of the sheet within the range that can be taken and photographed (500 μm in the lateral direction), and the average The value is defined as the number of graphite particles (A) bent at the surface portion of the sheet.

In the heat conductive sheet of the present invention, the bending point of the graphite particles (A) bent at the surface portion of the sheet is 10% or less, preferably 5% or less, more preferably 3% or less of the sheet thickness from the sheet surface. is there. When the bending point of the graphite particles (A) exceeds 10% of the sheet thickness from the surface of the sheet, there is a tendency that sufficient thermal conductivity cannot be obtained. In addition, when the bent portion is curved, a point obtained by extrapolation from each straight line is set as a bending point.
The position of the bending point of the graphite particles (A) bent at the surface portion of the sheet is measured by observing a cross section in the thickness direction of each side obtained by cutting the heat conductive sheet into a regular octagon using a fluorescence microscope. Specifically, for any 30 graphite particles (A) whose front end portions are bent at the surface portions on both sides of the sheet with respect to the cross section of any one side, from the surface of the sheet to the position of the bending point, The length in the thickness direction of the sheet is measured, and the ratio of the length to the thickness of the sheet is obtained.

In the heat conductive sheet of the present invention, the length of the bent portion of the graphite particles (A) bent at the surface portion of the sheet is 5 to 20%, preferably 10 to 20%, more preferably 15 to 20% of the sheet thickness. %. If the length of the bent portion of the graphite particles (A) is less than 5% of the sheet thickness, sufficient thermal conductivity cannot be obtained, and conversely, if it exceeds 20%, It tends to be inferior to the adhesiveness of the sheet and cannot serve as a sheet.
The length of the bent portion of the graphite particles (A) bent at the surface portion of the sheet is measured by observing a cross section in the thickness direction of each side obtained by cutting the heat conductive sheet into a regular octagon using a fluorescence microscope. . Specifically, for any 30 graphite particles (A) whose front end portions are bent at the surface portions on both sides of the sheet with respect to the cross section of any one side, the length of the bent portion is measured, The ratio of the length to the sheet thickness is obtained.

In addition, when one or both surfaces of the heat conductive sheet of the present invention has adhesiveness, the adhesive surface of the heat conductive sheet before use may be covered with a protective film in order to protect the adhesive surface. . Examples of the material for the protective film include resins such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyether naphthalate, and methylpentene film, and metals such as coated paper, coated cloth, and aluminum. Two or more kinds of these protective films may be combined to form a multilayer film, and a film obtained by treating the surface of the protective film with a release agent such as silicone or silica is preferably used. Also, if the front and back surfaces are covered with protective films with different peel strengths, it is possible to prevent the protective film on the other side from falling off by first peeling off one surface with weak peel strength and sticking it on the adherend. It is excellent in workability and preferable.
Further, it is preferable to provide an insulating film on one side or both sides because it can be used for a portion requiring electrical insulation. When the heat conductive sheet has both a protective film and an insulating film, the protective film is preferably the outermost layer from the viewpoint of protecting the heat conductive sheet.

The manufacturing method of the heat conductive sheet of this invention includes the process of producing a primary sheet, the process of obtaining the molded object by laminating or winding the primary sheet, and the process of obtaining the heat conductive sheet by slicing the molded object.
First, graphite particles (A) having a scaly shape, an elliptical shape, or a rod shape, in which the six-membered ring surface in the crystal is oriented in the scale direction, the major axis direction of the ellipse, or the major axis direction of the rod, and Tg Is pressed with a pressure of 5 to 10 MPa in a direction parallel to the orientation direction of the graphite particles (A) in the composition, Rolling molding, press molding, extrusion molding or coating is performed to a thickness of 20 times or less of the average value of the major axis of the graphite particles to produce a primary sheet in which the graphite particles (A) are oriented in a substantially parallel direction with respect to the main surface.

  The composition containing the graphite particles (A) and the organic polymer compound (B) can be obtained by mixing both, but the mixing method is not particularly limited. For example, the organic polymer compound (B) is dissolved in a solvent, the graphite particles (A) and other components are added thereto, and the mixture is stirred and dried, or roll kneading, mixing by a kneader, mixing by a brabender Mixing with an extruder or the like can be used.

  The thickness at the time of producing the primary sheet by pressing the composition at a pressure of 5 to 10 MPa is 20 times or less, preferably 2 to 0.2 times the average value of the major axis of the graphite particles (A). When the thickness exceeds 20 times the average value of the major axis of the graphite particles (A), the orientation of the graphite particles (A) becomes insufficient, and as a result, the thermal conductivity of the finally obtained thermal conductive sheet is low. It can get worse. The thickness can be adjusted by the pressing pressure.

  The composition is rolled, press-formed, extruded or coated to produce a primary sheet in which the graphite particles (A) are oriented in a direction substantially parallel to the main surface. This is preferable because the graphite particles (A) can be surely oriented.

  The state in which the graphite particles (A) are oriented in a substantially parallel direction with respect to the main surface of the sheet refers to a state in which the graphite particles (A) are oriented so as to lie on the main surface of the sheet. The orientation of the graphite particles (A) in the sheet plane is controlled by adjusting the flowing direction of the composition when the composition is molded.

  That is, the direction of the graphite particles (A) is controlled by adjusting the direction in which the composition is passed through a rolling roll, the direction in which the composition is extruded, the direction in which the composition is applied, and the direction in which the composition is pressed.

  Since the graphite particles (A) are basically anisotropic particles, the orientation of the graphite particles (A) is usually aligned by rolling, press forming, extruding or coating the composition. Arranged.

  Moreover, when producing the primary sheet, when the shape before molding of the composition containing the graphite particles (A) and the organic polymer compound (B) is a lump, the lump has a thickness (d0). On the other hand, the width of the primary sheet can be adjusted by rolling or pressing so that the thickness (dp) of the primary sheet after molding is dp / d0 <0.15, or by adjusting the shape corresponding to the cross-sectional shape of the primary sheet at the exit of the extruder. Extrusion molding is preferably performed so that the thickness (dp ′) is (dp ′ / W <0.15) with respect to (W). By molding so that dp / d0 <0.15 or dp ′ / W <0.15, the graphite particles (A) can be easily oriented in a substantially parallel direction with respect to the main surface of the sheet.

  Next, the primary sheet is laminated or wound to obtain a molded body. There is no restriction | limiting in particular about the method of laminating | stacking a primary sheet, For example, the method of laminating | stacking several primary sheets, the method of folding a primary sheet, etc. are mentioned.

  When laminating, the orientation of the graphite particles (A) in the sheet plane is aligned. The shape of the primary sheet when laminating is not particularly limited. For example, when a rectangular primary sheet is laminated, a prismatic shaped body is obtained, and when a circular primary sheet is laminated, a cylindrical shaped body is obtained. Is obtained.

  The method for winding the primary sheet is not particularly limited, and the primary sheet may be wound around the orientation direction of the graphite particles (A). The shape of the winding is not particularly limited, and may be, for example, a cylindrical shape or a rectangular tube shape.

  The pressure at the time of laminating the primary sheet and the pulling force at the time of winding are required because the slice surface is crushed for convenience of slicing at an angle of 0 to 30 degrees with respect to the normal line coming out from the primary sheet surface in the subsequent process. It is adjusted so that it is weak enough not to be less than the area and strong enough to adhere well between the sheets. Preferably, it adheres in the pressure range of 1-5 MPa.

  Usually, this adjustment can provide a sufficient adhesive force between the laminated surfaces or the wound surfaces. However, if insufficient, a solvent or an adhesive may be thinly applied to the primary sheet for lamination or winding. Lamination or winding may be performed under heating as appropriate.

Next, while pressing the molded body at a pressure of 0.01 to 0.5 MPa, it is sliced at an angle of 0 to 30 degrees, preferably an angle of 0 to 15 degrees, with respect to the normal line coming out from the primary sheet surface, A heat conductive sheet having a thickness of is obtained. When the slice angle exceeds 30 degrees, the thermal conductivity tends to decrease. By slicing the molded body while pressing it at a pressure of 0.01 to 0.5 MPa, the tip portion of the graphite particles (A) is bent at the surface portion on one or both sides of the sheet.
When the molded body is a laminated body, it may be sliced so as to be perpendicular or substantially perpendicular to the lamination direction of the primary sheet.

Further, when the molded body is a wound body, it may be sliced so as to be perpendicular or substantially perpendicular to the winding axis.
Furthermore, in the case of a cylindrical molded body in which circular primary sheets are laminated, the molded body may be sliced like a wig within the above angle range.

  Examples of the slicing method include a multi-blade method, a laser processing method, a water jet method, a knife processing method, and the like, but the knife processing method is preferable because the thickness of the heat conductive sheet can be easily maintained in parallel. However, in any case, it is necessary to have a panel surface that is pressed by applying a pressure of 0.01 to 0.5 MPa.

The cutting tool for slicing is not particularly limited, but is a slice member having a canna-like portion having a smooth board surface having a slit and a blade protruding from the slit, and the blade is If the protrusion length from the slit portion is adjustable according to the desired thickness of the heat conductive sheet, it is difficult to disturb the orientation of the graphite particles near the surface of the obtained heat conductive sheet, and It is preferable because a sheet having a desired thickness can be easily produced.
Specifically, it is preferable to use a plane or slicer with a sharp blade as the slice member. These blades can be easily made to have a desired thickness by allowing the protrusion length from the slit portion to be adjusted according to the desired thickness of the heat conductive sheet.
By cutting with these, it becomes easy to bend the front-end | tip part of a graphite particle (A) in the surface part of a sheet | seat. Moreover, it is easy to produce a thin sheet.

  The temperature range of the molded body when slicing is preferably −20 to 10 ° C., more preferably −10 to 0 ° C. When the temperature at the time of slicing exceeds 10 ° C., the molded body becomes soft and difficult to slice, and the orientation of the graphite particles tends to be disturbed.

  On the other hand, when the temperature is lower than −20 ° C., the molded body is hard and fragile and difficult to slice, and the tip portion of the graphite particles (A) cannot be bent at the surface portion of the sheet. In addition, the sheet tends to break immediately after slicing.

  Although the thickness of a heat conductive sheet is suitably set by a use etc., Preferably it is 0.05-3 mm, More preferably, it is 0.1-1 mm. When the thickness of the heat conductive sheet is less than 0.05 mm, handling as a sheet tends to be difficult, and when it exceeds 3 mm, the heat dissipation effect tends to be low. The slice width of the molded body is the thickness of the heat conductive sheet, and the slice surface is a contact surface of the heat conductive sheet with the heat generating body or the heat radiating body.

  The heat radiating device of the present invention is obtained by interposing the heat conductive sheet of the present invention or the heat conductive sheet obtained by the method for producing the heat conductive sheet of the present invention between the heat generator and the heat radiator. As a heat generating body, that whose surface temperature does not exceed 200 degreeC at least is preferable.

  When the surface temperature is likely to exceed 200 ° C., for example, near the nozzle of a jet engine, around the inside of a kiln pot, around the inside of a blast furnace, around the inside of a nuclear reactor, the outer shell of a spacecraft, etc. It is not suitable because the organic polymer compound in the heat conductive sheet or the heat conductive sheet obtained by the production method according to the present invention is likely to be decomposed.

  The temperature range in which the heat conductive sheet of the present invention or the heat conductive sheet manufactured by the method of manufacturing the heat conductive sheet of the present invention can be used particularly preferably is −10 to 120 ° C., such as semiconductor package, display, LED, electric lamp, etc. Is an example of a suitable heating element.

  On the other hand, as a heat sink, for example, a heat sink using aluminum, copper fins, plates, etc., an aluminum or copper block connected to a heat pipe, an aluminum or copper that circulates cooling liquid with a pump inside A typical example is a block, a Peltier element, and an aluminum or copper block having the same.

  The heat radiating device of the present invention is established by bringing each surface of the heat conductive sheet of the present invention or the heat conductive sheet obtained by the method of manufacturing the heat conductive sheet of the present invention into contact with the heat generating body and the heat radiating body. There is no limitation on the contact method as long as the heating element, the heat conductive sheet, and the heat dissipation element can be fixed in a sufficiently adhered state, but from the viewpoint of maintaining the adhesion, a method of screwing through a spring, a clip A contact method in which the pressing force is sustained, such as a method of pinching with a pin, is preferable.

  Hereinafter, the present invention will be described in detail by way of examples. In each example, the thermal conductivity as an index of thermal conductivity was determined by the following method. Since this method is affected by contact resistance, it is easy to confirm the effect of the present invention.

(Measurement of thermal conductivity)
A heat conductive sheet of 1 cm in length and 1.5 cm in width was sandwiched between the transistor (2SC2233) and the aluminum heat dissipation block, and current was passed through the transistor while pressing it. The transistor temperature: T1 (° C.) and the heat dissipation block temperature: T2 (° C.) are measured. From the measured value and applied power: W1 (W), the thermal resistance: X (° C./W) according to the following equation (I) Was calculated.

X = (T1-T2) / W1 Formula (I)
From the thermal resistance of the above formula: X (° C./W) and the thickness of the thermal conductive sheet: d (μm), the correction coefficient by a sample with a known thermal conductivity: C, the thermal conductivity: Tc ( W / mK) was estimated.

  Tc = C × d / X Formula (II)

Example 1
As the organic polymer compound (B), an acrylic ester copolymer resin (2-ethylhexyl acrylate / 2-hydroxyethyl acrylate / acrylic acid copolymer, manufactured by Hitachi Chemical Co., Ltd., weight average molecular weight: 437,000, Tg-64 .11 ° C., 25% by mass aqueous solution) 20.48 g, scale-like expanded graphite powder (manufactured by Hitachi Chemical Co., Ltd., trade name: HGF-L, average particle size 250 μm) as graphite particles (A), 5.93 g, difficult 1.94 g of acid-treated graphite powder (trade name: Moehen Z, average particle size: 120 μm) as a flame retardant and aromatic condensed phosphate ester (phosphate ester flame retardant, Daihachi Chemical Industry Co., Ltd.) 1.69 g (manufactured, trade name: CR-733S) was well mixed with a stainless steel bowl.

This was spread on a release-treated PET (polyethylene terephthalate) film, air-dried in a draft at room temperature for 3 hours, and then dried in a hot air dryer at 120 ° C. for 1 hour to obtain a composition. When the compounding ratio of each component with respect to the total volume of the composition was calculated from the specific gravity of each component, the graphite particles (A) were 30.0% by volume, the organic polymer compound (B) was 45.3% by volume, and the flame retardant was It was 24.7% by volume.
A part of this composition was rounded into a sphere having a diameter of 1 cm and formed into a sheet having a thickness of 0.5 mm with a small press. This was cut into 20 sheets and laminated again and pressed in the same manner. The surface of the sheet obtained by repeating this operation one more time was analyzed by X-ray diffraction. A peak corresponding to the (110) plane of graphite could not be confirmed in the vicinity of 2θ = 77 °, and the expanded graphite powder (HGF-L) used was “the six-membered ring plane in the crystal is oriented in the plane direction of the scale. I was able to confirm.

  This composition 1g was sandwiched between release-treated PET films and pressed with a tool surface of 5 cm × 10 cm for 10 seconds under the conditions of a tool pressure of 10 MPa and a tool temperature of 120 ° C., and a thickness of 0.3 mm A primary sheet was obtained. This operation was repeated to produce a large number of primary sheets.

  The obtained primary sheet was cut out to a size of 2 cm × 2 cm with a cutter, and 37 sheets were laminated with the orientation of the graphite particles aligned, and lightly pressed by hand to adhere between the sheets to obtain a molded article having a thickness of 1.1 cm. It was.

  Next, after cooling this molded body to −5 ° C. with dry ice, a 1.1 cm × 2 cm laminated section was pressed with a pressure of 7 MPa, and a canna (projection length of the sword portion from the slit portion: 3 mm) was used. And sliced at 0 degrees with respect to the normal line coming out from the primary sheet surface, that is, at an angle of 90 degrees with respect to the orientation direction of the graphite particles (A), and the length is 1.1 cm × width 2 cm × thickness 0 A heat conductive sheet (I) of .58 mm was obtained.

  This heat conductive sheet (I) is cooled to −50 ° C. with liquid nitrogen and cut using a microtome (manufactured by Daiwa Koki Co., Ltd.) so that the cross section in the thickness direction of the sheet can be seen. A 1 cm cross section was obtained. This was observed using a fluorescence microscope, and it was confirmed that the graphite particles were bent at the surface portion of the sheet (the angle was in the range of 60 to 90 degrees with the thickness direction of the sheet as an axis). Further, when the number of bent graphite particles was counted, it was 12 per 500 μm in the horizontal direction.

The cross section of the heat conductive sheet (I) was observed using a fluorescence microscope, the length from the surface of the sheet to the bending point of the graphite particles was measured, and the average value thereof was 12 μm. %Met. Moreover, when the length of the bent part was measured and the average value was calculated | required, it was 25 micrometers and was 10% of sheet | seat thickness.
The cross section of the heat conductive sheet (I) was observed using an SEM (scanning electron microscope), the major axis was measured from the direction in which about 50 arbitrary graphite particles were seen, and the average value was obtained. The average value of the major axis was 255 μm.
The cross section of the heat conductive sheet (I) is observed using an SEM (scanning electron microscope), and the angle with respect to the heat conductive sheet surface in the direction of the scale from the direction seen for any 50 graphite particles is measured, The average value was found to be 90 degrees, and it was confirmed that the surface direction of the scale of the graphite particles was oriented in the thickness direction of the heat conductive sheet.

  When the thermal conductivity of this thermal conductive sheet (I) was measured, it showed a good value of 50 W / mK. Further, the adhesion of the heat conductive sheet (I) to the transistor and the aluminum heat dissipation block was also good.

(Example 2)
As the organic polymer compound (B), an acrylic ester copolymer resin (2-ethylhexyl acrylate / 2-hydroxyethyl acrylate / acrylic acid copolymer, manufactured by Hitachi Chemical Co., Ltd., weight average molecular weight: 437,000, Tg-64 .11 ° C., 25 mass% aqueous solution) 1400 g, scale-like expanded graphite powder (manufactured by Hitachi Chemical Co., Ltd., trade name: HGF-L, average particle size 250 μm) as graphite particles (A), acid treatment as flame retardant Agitate 130 g of graphite (trade name: CR-733S, manufactured by Hitachi Chemical Co., Ltd.) and 110 g of aromatic condensed phosphate ester (phosphate ester flame retardant, manufactured by Daihachi Chemical Industry Co., Ltd., trade name: CR-733S). In addition, the composition was mixed by kneading with two rolls at 100 ° C. (manufactured by Kansai Roll Co., Ltd., test roll machine (8 × 20T roll)). Obtained in the form of a kneaded sheet.

  When the compounding ratio of each component with respect to the total volume of the composition was calculated from the specific gravity of each component, the graphite particles (A) were 30.0% by volume, the organic polymer compound (B) was 45.9% by volume, and the flame retardant was It was 24.1% by volume.

  The obtained kneaded sheet was chopped into a size of about 2 to 3 mm square and formed into a pellet shape having a thickness of 15 to 20 mm, using a Labo Plast Mill MODEL20C200 manufactured by Toyo Seiki, at 170 ° C. and a sheet shape having a width of 60 mm and a thickness of 2 mm. To obtain a primary sheet.

  The obtained primary sheet was cut to a size of 5 cm × 5 cm with a cutter, and acetone was thinly applied to the surface of the sheet to laminate 150 sheets, and lightly pressed by hand to adhere the sheets to obtain a molded body having a thickness of 30 cm. .

  Next, this molded body was cooled to −10 ° C. with dry ice, and then a 5 cm × 30 cm laminated section was pressed with a pressure of 10 MPa while being manufactured by Marunaka Iron Works Co., Ltd. (Slipping length: 0.11 mm) (slice at 0 degree with respect to the normal line coming out from the primary sheet surface, that is, at an angle of 90 degrees with respect to the orientation direction of the graphite particles (A)) ), A heat conductive sheet (II) having a length of 5 cm × width of 30 cm × thickness of 0.55 mm was obtained.

Thereafter, the properties of the heat conductive sheet (II) were determined in the same manner as in Example 1. The average value of the major axis of the graphite particles was 254 μm. The cross section in the thickness direction of the sheet was observed using a fluorescence microscope, and it was confirmed that the graphite particles were bent at the surface portion of the sheet (angle of 60 to 90 degrees with the thickness direction of the sheet as an axis). The number of graphite particles bent at the surface portion of the sheet was 15 per 500 μm in the lateral direction, and the average length from the sheet surface to the bending point was 10 μm, which was 4% of the sheet thickness. The average value of the length of the bent portion was 28 μm, which was 11% of the sheet thickness.
In addition, the cross section of the heat conductive sheet (II) is observed using an SEM (scanning electron microscope), and the angle from the direction in which about 50 arbitrary graphite particles are viewed to the surface of the heat conductive sheet is measured. And when the average value was calculated | required, it was 90 degree | times, and it was recognized that the surface direction of the scale of a graphite particle is orientating in the thickness direction of a heat conductive sheet.

  When the heat conductivity of the heat conductive sheet (II) was measured in the same manner as in Example 1, it showed a good value of 45 W / mK. Moreover, the adhesiveness with respect to the transistor and aluminum heat dissipation block of heat conductive sheet (II) was also favorable.

(Comparative Example 1)
Spherical natural graphite (average particle diameter of 20 μm) was used instead of scale-like expanded graphite powder (manufactured by Hitachi Chemical Co., Ltd., trade name: HGF-L, average particle diameter of 250 μm) as graphite particles (A). The heat conducting sheet (III) having a length of 1.1 cm, a width of 2 cm and a thickness of 0.56 mm was obtained in the same manner as in Example 1.

  When the compounding ratio of each component with respect to the total volume of the composition was calculated from the specific gravity of each component, the graphite particles (A) were 30.0% by volume, the organic polymer compound (B) was 45.9% by volume, and the flame retardant was It was 24.1% by volume.

  Thereafter, the properties of the heat conductive sheet (III) were obtained by operating in the same manner as in Example 1. The average value of the major axis of the graphite particles was 22 μm. The cross section in the thickness direction of the sheet was observed using a fluorescence microscope. However, since the angle of the graphite particles with respect to the surface of the heat conductive sheet in the major axis direction was not clear, the indexing was difficult and no orientation in the thickness direction of the sheet was observed.

  When the heat conductivity of the heat conductive sheet (III) was measured in the same manner as in Example 1, it showed a very low value of 1.2 W / mK. In addition, the adhesiveness with respect to the transistor and aluminum heat dissipation block of heat conductive sheet (III) was favorable.

(Comparative Example 2)
As the organic polymer compound (B), an acrylic ester copolymer resin (2-ethylhexyl acrylate / 2-hydroxyethyl acrylate / acrylic acid copolymer, manufactured by Hitachi Chemical Co., Ltd., weight average molecular weight: 437,000, Tg-64 .11 ° C., 25% by mass aqueous solution) 20.48 g instead of acrylic ester copolymer resin (methyl methacrylate / ethyl acrylate / butyl acrylate / acrylonitrile / acrylic acid copolymer, manufactured by Nagase ChemteX Corporation) (Product name: SG-P-26DR, weight average molecular weight: 200,000, Tg 28 ° C.) Except for using 5.12 g, the same operation as in Example 1 was performed, and the length was 1.1 cm × width 2 cm × thickness. A 0.6 mm heat conductive sheet (IV) was obtained.

  When the compounding ratio of each component with respect to the total volume of the composition was calculated from the specific gravity of each component, the graphite particles (A) were 30.0% by volume, the organic polymer compound (B) was 45.9% by volume, and the flame retardant was It was 24.1% by volume.

Thereafter, the properties of the heat conductive sheet (IV) were determined in the same manner as in Example 1. The average value of the major axis of the graphite particles was 258 μm. The cross section in the thickness direction of the sheet was observed using a fluorescence microscope, and it was confirmed that the graphite particles were not bent at the surface portion of the sheet.
In addition, the cross section of the heat conductive sheet (IV) is observed using an SEM (scanning electron microscope), and the angle of the surface direction of the scale from the direction seen for any 50 graphite particles is measured with respect to the surface of the heat conductive sheet. And when the average value was calculated | required, it was 90 degree | times, and it was recognized that the surface direction of the scale of a graphite particle is orientating in the thickness direction of a heat conductive sheet.

  When the heat conductivity of the heat conductive sheet (IV) was measured in the same manner as in Example 1, it showed a low value of 15 W / mK. Further, the adhesion of the heat conductive sheet (IV) to the transistor and the aluminum heat dissipation block was also poor.

(Comparative Example 3)
A molded body of 2 cm long × 2 cm wide × 1 cm thick produced in the same manner as in Example 1 was cooled to −5 ° C. with dry ice, and then a 1.1 cm × 2 cm laminated section was cut using a cutter knife. (Cut at an angle of 0 degrees with respect to the normal line coming out of the primary sheet surface, that is, 90 degrees with respect to the orientation direction of the graphite particles (A)), 1.1 cm long × 2 cm wide × 0.60 mm thick A heat conductive sheet (V) was obtained. At this time, the operation of pressing the molded body was not performed.

Thereafter, the properties of the heat conductive sheet (V) were determined in the same manner as in Example 1. The average value of the major axis of the graphite particles was 254 μm. The cross section in the thickness direction of the sheet was observed using a fluorescence microscope, and it was confirmed that the graphite particles were not bent at the surface portion of the sheet.
In addition, the cross section of the heat conductive sheet (V) is observed using an SEM (scanning electron microscope), and the angle from the direction in which the arbitrary 50 graphite particles are viewed to the surface of the heat conductive sheet is measured. And when the average value was calculated | required, it was 90 degree | times, and it was recognized that the surface direction of the scale of a graphite particle is orientating in the thickness direction of a heat conductive sheet.

  When the heat conductivity of the heat conductive sheet (V) was measured in the same manner as in Example 1, it showed a low value of 12 W / mK. In addition, the adhesiveness with respect to the transistor and aluminum heat dissipation block of a heat conductive sheet (V) was favorable.

The figure which shows the bending of the graphite particle (A) front-end | tip part in the heat conductive sheet surface part.

Claims (11)

Graphite particles (A) that are scale-like, elliptical, or rod-shaped, with the six-membered ring surface in the crystal oriented in the plane direction of the scale, the major axis of the ellipse, or the major axis of the rod, and Tg of 0 A heat conductive sheet comprising a composition containing an organic polymer compound (B) having a temperature of ℃ or less,
The surface direction of the scale of the graphite particles (A), the major axis direction of the ellipsoid or the major axis direction of the rod is oriented in the thickness direction inside the sheet, and the graphite particles ( A heat conductive sheet in which the tip portion of A) is bent at an angle of 60 to 90 degrees with the thickness direction of the sheet as an axis in a direction along the surface of the sheet.   2. The heat conductive sheet according to claim 1, wherein the number of graphite particles (A) bent at the surface portion of the sheet is 5 to 20 per 500 μm in a lateral length in a cross section in the thickness direction of the sheet.   The heat conductive sheet according to claim 1 or 2, wherein the bending point of the graphite particles (A) bent at the surface portion of the sheet is located within 10% of the sheet thickness from the surface of the sheet.   The heat conductive sheet according to any one of claims 1 to 3, wherein the bent portion of the graphite particles (A) bent at the surface portion of the sheet has a length of 5 to 20% of the sheet thickness.   5. The composition according to claim 1, wherein the graphite particles (A) are blended in an amount of 10 to 50% by volume, and the organic polymer compound (B) is blended in an amount of 10 to 50% by volume. The heat conductive sheet according to item. Graphite particles (A) that are scale-like, elliptical, or rod-shaped, with the six-membered ring surface in the crystal oriented in the plane direction of the scale, the major axis of the ellipse, or the major axis of the rod, and Tg of 0 The composition containing the organic polymer compound (B) having a temperature of not more than 0 ° C. is pressed at a pressure of 5 to 10 MPa in a direction parallel to the orientation direction of the graphite particles (A) in the composition, and the main surface is almost Producing a primary sheet in which the graphite particles (A) are oriented in parallel directions;
Laminating the primary sheet to obtain a molded body,
While pressing the molded body at a pressure of 0.01 to 0.5 MPa, the sheet is sliced at an angle of 0 to 30 degrees with respect to the normal from the primary sheet surface to obtain a heat conductive sheet, and the surface on one or both sides of the heat conductive sheet A method for producing a heat conductive sheet, characterized in that the tip portion of the graphite particles (A) is bent at an angle of 60 to 90 degrees about the thickness direction of the sheet in a direction along the surface of the sheet. Graphite particles (A) that are scale-like, elliptical, or rod-shaped, with the six-membered ring surface in the crystal oriented in the plane direction of the scale, the major axis of the ellipse, or the major axis of the rod, and Tg of 0 The composition containing the organic polymer compound (B) having a temperature of not more than 0 ° C. is pressed at a pressure of 5 to 10 MPa in a direction parallel to the orientation direction of the graphite particles (A) in the composition, and the main surface is almost Producing a primary sheet in which the graphite particles (A) are oriented in parallel directions;
The primary sheet is wound around the orientation direction of the graphite particles (A) to obtain a molded body,
While pressing the molded body at a pressure of 0.01 to 0.5 MPa, the sheet is sliced at an angle of 0 to 30 degrees with respect to the normal from the primary sheet surface to obtain a heat conductive sheet, and the surface on one or both sides of the heat conductive sheet A method for producing a heat conductive sheet, characterized in that the tip portion of the graphite particles (A) is bent at an angle of 60 to 90 degrees about the thickness direction of the sheet in a direction along the surface of the sheet. Slicing the molded body is performed using a slice member having a smooth board surface having a slit and a blade portion protruding from the slit portion,
The said blade part is a manufacturing method of the heat conductive sheet of Claim 6 or 7 which can adjust the protrusion length from the said slit part according to the desired thickness of the said heat conductive sheet.   The method for manufacturing a heat conductive sheet according to claim 8, wherein the slice member is a plane or a slicer.   The manufacturing method of the heat conductive sheet as described in any one of Claims 6-9 which slices the said molded object in the temperature range of -20-10 degreeC.   A heat conductive sheet according to any one of claims 1 to 5 or a heat conductive sheet obtained by the method for producing a heat conductive sheet according to any one of claims 6 to 10, comprising a heating element and a radiator. Heat dissipation device interposed between the two.