JP5009054B2 - Manufacturing method of heat dissipation sheet - Google Patents

Description

The present invention relates to a heat dissipation sheet and a manufacturing method thereof.

In recent years, problems such as unstable operation of components due to heat generated from ICs and CPUs used in electrical devices such as plasma displays, transistors, capacitors, personal computers, and electronic components have arisen. For this reason, heat is diffused by providing a heat dissipation sheet between a heat generator such as an electronic component and a heat sink such as a heat sink or a heat pipe.

As such a heat-dissipating sheet, a heat-dissipating sheet in which a heat-conductive filler is added to a matrix resin has been proposed in the past, and a heat-dissipating sheet composed of a composition in which heat-sensitive spherical magnesia is appropriately combined with granular alumina in the matrix resin, boron nitride , Heat dissipation sheets using thermally conductive fillers such as aluminum nitride and aluminum oxide, oxide particles such as aluminum oxide and titanium oxide, nitride particles such as boron nitride, carbide particles such as silicon carbide, metals such as copper and aluminum A thermally conductive sheet using particles is disclosed. However, since the thermal conductivity is low, a high heat dissipation effect cannot be expected.

Patent Document 1 discloses a heat dissipating sheet in which a plurality of graphite sheets are laminated and the ab surface of the graphite crystal is perpendicular to the sheet surface of the heat dissipating sheet. This sheet exhibits high thermal conductivity because the graphite sheet is continuous in the sheet thickness direction. However, regarding the electrical insulation required for the heat dissipation sheet, since the graphite sheet is a high conductor, it is necessary to provide a separate electrical insulation layer, which substantially reduces the thermal conductivity and man-hours in manufacturing. There was a problem that led to an increase.
JP 2006-303240 A

In view of the above-mentioned present situation, the present invention aims to provide a heat radiating sheet having high thermal conductivity and high insulation and a method for producing the same.

In the present invention , the base layer and the diamond layer are alternately laminated,
The base material layer is formed of a flexible material,
The diamond layer is a method of manufacturing a heat dissipation sheet formed in a direction greater than 0 ° and 90 ° or less with respect to the sheet surface of the heat dissipation sheet,
A diamond layer using a dispersion in which diamond having an average particle diameter of 10 to 500 nm obtained by reaggregating diamond having an average particle diameter of 1 to 30 nm in water is dispersed on the base material layer formed of a flexible material. Forming the step (I), the step (II) of laminating the two-layer laminate obtained in the step (I) so that the base material layer and the diamond layer are alternately laminated, and the step (I) And (III) including a step of cutting the multilayer body obtained in II) so that the diamond layer is formed in a direction larger than 0 ° and not larger than 90 ° with respect to the sheet surface of the heat dissipation sheet. Ru manufacturing method der of the heat dissipation sheet.
In the manufacturing method of this invention, it is preferable that the said diamond layer is formed in the direction of 60-90 degrees with respect to the sheet | seat surface of a thermal radiation sheet.
In the manufacturing method of the present invention, in the sheet surface of the heat dissipation sheet, the area ratio of the diamond layer is 4 to 10% with respect to the entire surface of the sheet, and the thickness of the sheet is 0.1 to 1.0 mm. It is preferable that
Hereinafter, the present invention will be described in detail.

The heat radiating sheet of the present invention is formed of a base material layer and a diamond layer disposed so as to be in contact with the heat generating body and the heat radiating body in use (formed in a direction larger than 0 ° and not larger than 90 ° with respect to the sheet surface of the heat radiating sheet). Layer) are alternately laminated. Since it is such a structure, it has high heat conductivity, and also has high insulation.

A heat-dissipating sheet in which a filler such as alumina is dispersed has high insulation, but its thermal conductivity is not sufficient. Further, as described above, the heat dissipation sheet in which the base sheet and the graphite sheet are alternately laminated has high thermal conductivity, but has low insulation. Thus, although it is generally difficult to achieve both high thermal conductivity and high insulation, it is possible to achieve both in the present invention.

That is, when the heat-dissipating sheet of the present invention is placed between the heat generating element and the heat dissipating element, the diamond layer on the sheet surface excellent in flexibility can be brought into good contact with the heat generating element and the heat dissipating element. The generated heat can be transferred in the direction of the radiator through the diamond layer, and good heat dissipation can be obtained. Therefore, high heat conductivity and heat dissipation are exhibited in the heat dissipation sheet. In addition, since the diamond layer is included in the sheet, extremely high insulating properties can be exhibited due to the insulating properties of diamond.

The heat-dissipating sheet of the present invention comprises a base material layer formed of a flexible material and a diamond layer formed alternately in a direction of greater than 0 ° and 90 ° or less with respect to the sheet surface of the heat-dissipating sheet. It is.

Hereinafter, the heat-radiation sheet of this invention is demonstrated concretely using FIGS.
FIG. 1 is an example of a cross-sectional view in the direction perpendicular to the sheet surface of the heat dissipating sheet of the present invention, and shows a laminated state of a diamond layer and a flexible material in the sheet. Moreover, FIG. 2 is an example of the schematic diagram of the sheet | seat surface of the thermal radiation sheet | seat of this invention, and shows an example of the sheet | seat surface 4 in FIG.

As shown in FIGS. 1 and 2, the heat-dissipating sheet 1 of the present invention has base material layers 2 and diamond layers 3 alternately laminated.
The diamond layer 3 in the present invention is not particularly limited as long as it is a layer formed of diamond and capable of expressing desired thermal conductivity in the heat dissipation sheet 1. Further, the diamond particles may be a layer covering the entire surface of the base material layer 2 or a layer covering a part of the surface of the base material layer 2.

The diamond layer 3 in the heat dissipation sheet 1 of the present invention is formed in a direction greater than 0 ° and not greater than 90 ° with respect to the sheet surface 4 of the heat dissipation sheet 1. That is, in the heat radiation sheet 1 (cross-sectional view in the direction perpendicular to the sheet surface 4) in FIG. 1, the angle 7 formed by the sheet surface direction 5 and the diamond layer direction 6 is greater than 0 ° and 90 ° or less.

In the present invention, the sheet surface 4 of the heat dissipation sheet 1 means the front and back surfaces of the heat dissipation sheet 1. In the heat radiating sheet 1, when used, one sheet surface functions as a heat receiving surface that contacts the heat generating element and receives heat from the heat generating element, and the other sheet surface functions as a heat radiating surface that contacts the heat radiating element and transfers heat to the heat radiating element. Function. In the present invention, since the angle 7 is greater than 0 ° and not more than 90 °, the heat-dissipating sheet 1 has a form in which the diamond layer 3 is exposed on the surface 4 (FIG. 2). Furthermore, the base material layer 2 is formed of a flexible material.

Therefore, when the heat radiating sheet 1 is used between the heat generating body and the heat radiating body, the exposed diamond layer 3 can be brought into good contact with the heat generating body and the heat radiating body. Therefore, extremely high thermal conductivity can be obtained by using the diamond layer 3 in contact with the material. Further, due to the nature of the diamond layer 3, high insulation can be imparted to the sheet.

The diamond layer 3 is preferably formed in a direction of 60 to 90 ° with respect to the sheet surface 4 of the heat dissipation sheet 1. That is, the angle 7 in FIG. 1 is preferably 60 to 90 °. In this case, the elastic modulus in the sheet thickness direction using hard diamond can be reduced, the adhesion as an inclusion between the heating element and the heat radiating body can be increased, the contact thermal resistance can be reduced, and the heat transfer effect can be increased. it can. As a result, high thermal conductivity can be obtained. In addition, high insulation can be exhibited.

In the heat dissipation sheet 1 of the present invention, the diamond layer 3 is obtained by using a dispersion in which diamond having an average particle diameter of 10 to 500 nm obtained by reaggregating diamond having an average particle diameter of 1 to 30 nm in water is dispersed. It is preferable. Thereby, the said effect can be acquired favorably.

The method for producing the diamond dispersion is not particularly limited as long as the dispersion can be obtained, and can be produced by a conventionally known method. For example, the method can be produced by the following method.
The raw material diamond secondary aggregated to a primary particle size of 1 to 15 nm and an average particle size of 100 to 300 nm is washed with an alkali and an acid to remove impurity metals such as aluminum, iron and manganese, and then neutralized. The neutralized diamond is crushed into diamond having an average particle diameter of 1 to 30 nm. The crushed diamond having an average particle diameter of 1 to 30 nm is re-agglomerated in water by a known method to obtain a dispersion of diamond having an average particle diameter of 10 to 500 nm. As said alkali, well-known basic compounds, such as sodium hydroxide, potassium hydroxide, aqueous ammonia, can be used. Moreover, as said acid, well-known acid compounds, such as inorganic acids, such as hydrochloric acid, nitric acid, a sulfuric acid, and various organic acids, can be used. Furthermore, the crushing method is not particularly limited, and the crushing can be performed by using a known airflow crusher or mechanical crusher.

In the above, diamond having an average particle diameter of 1 to 30 nm is used. If the average particle diameter of the diamond is less than 1 nm, a regular crystal structure of diamond cannot be obtained, and there is a possibility that the number of defect structures increases. If it exceeds 30 nm, reaggregation may not be controlled. The average particle size is preferably 1 to 15 nm, and more preferably 5 to 15 nm.

Further, in the above, a dispersion liquid in which diamond having an average particle diameter of 10 to 500 nm obtained by reaggregating the diamond having an average particle diameter of 1 to 30 nm in water is used. If the average particle size in the dispersion is less than 10 nm, aggregation may gradually proceed and the average particle size may increase. When it exceeds 500 nm, there is a possibility that it will not aggregate any more. The average particle size in the dispersion is preferably 30 to 300 nm.

In this specification, the average particle diameter means a volume-based median cumulative value (50% particle diameter, d50) obtained from a normal distribution function, and the average particle diameter of diamond in the dispersion is, for example, laser diffraction. It can be measured with a particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

In the sheet surface 4 of the heat dissipation sheet 1 of the present invention, the area ratio of the diamond layer 3 to the entire sheet surface 4 is preferably 4 to 20%. That is, in the sheet surface 4 of FIG. 2, the ratio of the area occupied by the diamond layer 3 to the total area 100% of the sheet surface 4 including the base material layer 2 and the diamond layer 3 (the total area of the diamond layer 3 in FIG. 2) is It is preferable that it is 4 to 20%. In this case, the above effect can be obtained satisfactorily. If it exceeds 20%, the flexibility of the heat-dissipating sheet is lowered and the adhesion to the heating element is lowered, so that the thermal conductivity may be lowered. More preferably, it is 5 to 15%.

The base material layer 2 in the heat dissipation sheet 1 of the present invention is a layer formed of a flexible material, and for example, a flexible sheet can be used.
The flexible material is not particularly limited, and any conventionally used material can be used as long as it does not interfere with the thermal conductivity and insulation of the heat dissipation sheet 1. For example, elastomers such as polyurethane, silicone rubber, ethylene propylene rubber, polyolefin, polyester, and polyamide can be used. Among these, polyurethane is preferable because it can be easily softened, has excellent mechanical strength, and can obtain high thermal conductivity and insulation.

Examples of the polyurethane include those obtained by reacting a polyol with a polyisocyanate. For example, a prepolymer obtained by reacting a polyol with a polyisocyanate is further reacted with a crosslinking agent. It can be obtained by a method or the like.

The polyol is not particularly limited, and examples thereof include polyether polyols such as polyoxytetramethylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, and polybutylene glycol; polycarbonate diol, neopentyl glycol, polyethylene adipate ester, polyethylene butylene adipate Mention may be made of polyester polyols such as esters, polybutylene adipate esters, caprolactone ester diols and the like.

It does not specifically limit as said polyisocyanate, A conventionally well-known thing can be used, For example, aliphatic isocyanate, alicyclic isocyanate, aromatic isocyanate etc. can be mentioned. As said aliphatic isocyanate, a C6-C10 aliphatic diisocyanate etc. are mentioned, for example. Specific examples include 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and the like. Moreover, the isocyanurate body of hexamethylene diisocyanate and isophorone diisocyanate, the biuret body, the modified body of an adduct body, etc. can be mentioned. Examples of the alicyclic isocyanate include alicyclic diisocyanates such as isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, norbornane diisocyanate (NBDI), and the like. Examples of the aromatic isocyanate include tolylene diisocyanate (TDI), phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate, xylylene diisocyanate (XDI), carbodiimide-modified MDI, and the like. Can be mentioned.

The crosslinking agent is not particularly limited, and examples thereof include low molecular diols such as ethylene glycol, 1,4-butanediol, diethylene glycol, trimethylolpropane, 1,6-hexanediol, and neopentyl glycol; ethylenediamine, hexamethylenediamine, Examples include diamines such as isophorone diamine.

When polyurethane obtained by reacting castor oil-modified polyol with polyisocyanate is used, low hardness, high flexibility, excellent mechanical strength, high thermal conductivity, and high insulation can be obtained. It becomes.

The said castor oil modified polyol means the thing of the broad sense which consists of a castor oil or a castor oil derivative.
Examples of the castor oil-modified polyol include, for example, castor oil, dehydrated castor oil, modified products thereof; transesterification or esterification of ricinoleic acid, which is a castor oil fatty acid, with a low molecular polyol (molecular weight 60 to 500), a polyether polyol, and a polyester polyol. The polyol etc. which are obtained by this can be mentioned. Other castor oil-modified polyols include partially dehydrated castor oil, partially acylated castor oil (partially acetylated castor oil, etc.), castor oil alkylene oxide adduct, castor oil epoxide, castor oil halide, and bisphenol alkylene oxide adduct. Castor oil fatty acid mono- or diester, esterified product of dimer acid and castor oil modified polyol, transesterified product of polymerized castor oil and caprolactone, condensate of dimer or more of castor oil fatty acid, or condensate thereof and polyhydric alcohol Examples of the ester may also be mentioned. Also, hydrogenated products of castor oil or castor oil derivatives such as hydrogenated castor oil can be used.
It does not specifically limit as polyisocyanate made to react with the said castor oil modified polyol, For example, the thing similar to what was mentioned above can be used.

It does not specifically limit as a manufacturing method of the said base material layer 2, It can manufacture using a conventionally well-known sheet forming method. For example, when rubber (matrix elastomer) is obtained by mixing and reacting a liquid material (polyurethane, etc.), an additive is added to the liquid material as necessary, and the mixture is stirred and dispersed to disperse the mixture. It can be suitably manufactured by pouring into a forming mold, heating and curing, and demolding after curing.
Moreover, it can also manufacture using methods, such as extrusion molding, a roll, and a calendar process, besides the said method.
The base material layer 2 may be subjected to corona treatment. Moreover, you may shape | mold with the said manufacturing method and cut | disconnect a sheet | seat as needed.

The heat dissipation sheet 1 of the present invention may include a high thermal conductive filler.
As the high thermal conductive filler, various kinds of conventionally used materials can be used. For example, aluminum hydroxide, aluminum oxide, silicon dioxide, titanium dioxide, mica, potassium titanate, iron oxide, talc, etc. Examples thereof include oxide particles, nitride particles such as boron nitride, silicon nitride, and aluminum nitride, carbide particles such as silicon carbide, and metal particles such as copper and aluminum. Moreover, you may mix | blend conventionally used additives, such as a hardening | curing agent, a processing aid, and a characteristic improvement agent, suitably.

The heat dissipation sheet 1 of the present invention preferably has a sheet thickness of 0.1 to 1.0 mm. That is, it is preferable that the thickness 8 in the heat dissipation sheet 1 of FIG. Thereby, since the practical intensity | strength of a heat radiating member is ensured and it becomes a suitable heat conduction distance, a favorable heat-transfer effect can be expressed. If it is less than 0.1 mm, the strength is lowered and there is a risk of breakage. If it exceeds 1 mm, the effect of heat transfer may be reduced. The thickness is more preferably 0.1 to 0.5 mm.

The manufacturing method of the heat-radiation sheet 1 of this invention will not be specifically limited if it is a method with which the base material layer 2 and the diamond layer 3 were laminated | stacked alternately, A conventionally well-known method can be used. In particular, a dispersion in which diamond having an average particle diameter of 10 to 500 nm obtained by reaggregating diamond having an average particle diameter of 1 to 30 nm in water is dispersed in water on a base material layer formed of a flexible material. The step (I) of forming a diamond layer, the step (II) of laminating the two-layer laminate obtained in the step (I) so that the base layer and the diamond layer are alternated, and the step A step (III) including a step (III) of cutting the multilayer body obtained in (II) so that the diamond layer is formed in a direction larger than 0 ° and not larger than 90 ° with respect to the sheet surface of the heat dissipation sheet. Can do.

In the step (I), as a method for forming a diamond layer using a diamond dispersion, for example, a printing method, a spray method, a spin coating method, a dipping method, or the like can be used. The base material layer and the dispersion liquid are the same as those described above. After application, the diamond layer can be obtained by drying by a known method.

In the step (II), a large number of two-layer laminates (laminates comprising a base layer and a diamond layer) obtained in the step (I) are alternately laminated on the base layer and the diamond layer, respectively. The method is not particularly limited as long as the target multilayer body (a multilayer body in which a large number of both layers are alternately stacked) is obtained, and a conventionally known lamination method can be employed. For example, the target multilayer body can be produced by laminating (adhering) each two-layer laminate using an adhesive so that both layers are alternated.

The adhesive is not particularly limited, and a conventionally known adhesive can be used. For example, an acrylic adhesive, an epoxy adhesive, a silicone adhesive, a rubber adhesive, an olefin adhesive, and a polyester adhesive Adhesives, polyamide adhesives, polysulfide adhesives, polyisobutylene adhesives, vinyl acetate adhesives, latex adhesives, PVA adhesives, EVA (ethylene vinyl acetate) adhesives, vinyl chloride adhesives And phenolic adhesives, polyurethane adhesives, cyanoacrylate adhesives, melamine adhesives, and the like.

In the step (III), the multilayer body obtained in the step (II) is manufactured, and in the heat radiating sheet, the diamond layer is formed in a direction larger than 0 ° and not larger than 90 ° with respect to the sheet surface of the heat radiating sheet. This can be done by cutting so that it becomes a solid. That is, the manufactured multilayer body can be performed using a conventionally known cutting method so that the angle 7 shown in FIG. 1 becomes a target angle (an angle greater than 0 ° and 90 ° or less). For example, when manufacturing a heat dissipation sheet having an angle 7 of 90 °, the multilayer body obtained in step (II) is cut in a direction substantially perpendicular to the sheet surface of the base material layer constituting the multilayer body. Can be obtained. A heat dissipation sheet having an angle 7 of 90 ° is excellent in productivity.

As said cutting method, the method of using a wire, a laser cutting machine, a water jet cutting machine etc. can be mentioned, for example. Among these, a water jet cutting machine is preferable. In this case, a heat dissipation sheet having high thermal conductivity and high insulation can be obtained satisfactorily.

The heat radiating sheet of the present invention can efficiently transfer heat from the heating element to the heat radiating element by the diamond layer exhibiting high thermal conductivity and high insulation. For this reason, high thermal conductivity and heat dissipation can be obtained. Also, high electrical insulation can be obtained.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail, this invention is not limited only to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Production example 1 Production of diamond dispersion Aluminum, iron, manganese by washing raw material diamond secondary aggregated with primary particle size of 1-15 nm and average particle size of 100-300 nm with potassium hydroxide and nitric acid After removing the impurity metal such as, it was neutralized. The neutralized diamond was crushed into diamond having an average particle diameter of 5 to 15 nm. The crushed diamond having an average particle diameter of 5 to 15 nm was re-agglomerated in water to obtain a dispersion of diamond having an average particle diameter of 150 to 200 nm. In addition, the said crushing was performed with the bead mill.

Example 1 Production of heat-dissipating sheet A rubber sheet (sheet made of EPDM) having a length and width of 50 mm and a thickness of 500 μm was prepared, and a diamond dispersion was applied onto the sheet with a spray coater and then dried to form a film. did. This operation was repeated until the thickness of the diamond film reached 50 μm. A silicone adhesive was applied to the formed diamond film at a thickness of 10 μm, and 16 sheets of this sheet were bonded while pressing from above and below to obtain a laminate having a thickness of about 10 mm. Next, the laminate was cut into a thickness of 1 mm perpendicular to the diamond film to obtain a laminate cross-sectional sheet (heat dissipating sheet: a sheet having an angle 7 of 90 ° in FIG. 1).
The cutting was performed using a water jet cutting machine. Moreover, the area ratio which a diamond layer occupies with respect to the sheet | seat surface of the obtained thermal radiation sheet was 8.3%.

Comparative Example 1 Production of conventional products (rubber + alumina)
One-component room temperature curing silicone rubber (manufactured by Shin-Etsu Silicone: KE3423) and thermal aluminum oxide (manufactured by Showa Denko: AS-40: average particle size 12 μm) were mixed.
This mixed solution was sandwiched between two release papers (used as a sheet molding die) and calendered to obtain a heat radiation sheet having a thickness of 1.0 mm (aluminum oxide content 20% by volume).

Comparative Example 2 Production of conventional products (graphite laminate)
A graphite sheet having a length and width of about 50 mm and a thickness of about 100 μm was prepared, and an epoxy adhesive was applied on one side of the graphite sheet so as to have a thickness of about 10 μm. Next, 500 sheets of adhesive-coated graphite sheets were stacked and stacked, and pressed from above and below to be firmly bonded to obtain a graphite sheet stack having a thickness of about 55 mm.
Next, it was cut into a thickness of 1.0 mm perpendicular to the graphite sheet to obtain a laminate cross-sectional sheet (heat dissipating sheet).

Evaluation (thermal conductivity)
About the heat conductivity of the thermal radiation sheet obtained by the Example and the comparative example, it measured by the steady-state heat-conductivity measuring method by a heat conductivity measuring machine (Thermolab 2 by Kato Tech Co., Ltd.). The results are shown in Table 1.
(Measurement condition)
Water at room temperature is poured into the water box, a 5 × 5 cm sample is placed on the box, and a hot plate of the BT box on the sample is placed on the sample. After reaching steady state, the heat flow loss (W) of the BT box is read with a panel meter.
Since the heat flow loss (W) in the steady state can be expressed by the following equation, the thermal conductivity is obtained.
W = K × (A · ΔT / D)
W: Heat flow loss in steady state D: Sample thickness ΔT: Sample temperature difference A: BT hot plate area K: Thermal conductivity

[Electrical insulation]
The electrodes were placed on the top and bottom of the sample, a constant current (I) was passed through the cross-sectional area S, and the potential difference (V) between the electrodes separated by a distance L was measured.
ρv = (V / I) · (S / L)
ρv: Volume resistivity

From Table 1, in Example 1, while showing high heat conductivity, it also had high insulation. On the other hand, in Comparative Example 1, the thermal conductivity was low, and in Comparative Example 2, the insulation was low. That is, the conventional product cannot achieve both high thermal conductivity and high insulation.

The heat dissipation sheet of the present invention can be suitably used for heat dissipation of heating elements such as ICs and CPUs used in electrical equipment and electronic components.

It is sectional drawing of the orthogonal | vertical direction with respect to the sheet | seat surface of the thermal radiation sheet | seat of this invention. It is the schematic of the sheet | seat surface in the thermal radiation sheet | seat of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat dissipation sheet 2 Base material layer 3 Diamond layer 4 Sheet surface 5 of heat dissipation sheet Sheet surface direction 6 of heat dissipation sheet Diamond layer direction 7 in heat dissipation sheet Angle 8 formed by sheet surface direction 5 of heat dissipation sheet and diamond layer direction 6 Sheet thickness

Claims (3)

The base material layer and the diamond layer are laminated alternately,
The base material layer is formed of a flexible material,
The diamond layer is a method of manufacturing a heat dissipation sheet formed in a direction greater than 0 ° and not more than 90 ° with respect to the sheet surface of the heat dissipation sheet,
A diamond layer using a dispersion in which diamond having an average particle diameter of 10 to 500 nm obtained by reaggregating diamond having an average particle diameter of 1 to 30 nm in water is dispersed on the base material layer formed of a flexible material. Forming (I),
Step (II) of laminating each two-layer laminate obtained in the step (I) so that the base material layer and the diamond layer are alternately laminated,
Cutting the multilayer body obtained in the step (II) so that the diamond layer is formed in a direction larger than 0 ° and not larger than 90 ° with respect to the sheet surface of the heat dissipation sheet. A method for producing a heat dissipation sheet. The method for manufacturing a heat dissipation sheet according to claim 1, wherein the diamond layer is formed in a direction of 60 to 90 ° with respect to the sheet surface of the heat dissipation sheet. 3. The heat dissipation sheet according to claim 1, wherein the area ratio of the diamond layer is 4 to 10% and the thickness of the sheet is 0.1 to 1.0 mm with respect to the entire surface of the heat dissipation sheet. Manufacturing method .

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