JP6379320B1 - Electromagnetic wave absorbing heat conducting sheet, method for producing electromagnetic wave absorbing heat conducting sheet, and semiconductor device - Google Patents

Abstract

An electromagnetic wave absorbing heat conductive sheet having excellent heat conductivity and electromagnetic wave absorbability is provided. In order to solve the above problems, an electromagnetic wave absorbing heat conductive sheet of the present invention comprises a polymer matrix component, a magnetic metal powder, and a fibrous heat conductive filler oriented in one direction. It is characterized by that. [Selection] Figure 2

Description

  The present invention relates to an electromagnetic wave absorbing heat conductive sheet, a method for producing an electromagnetic wave absorbing heat conductive sheet, and a semiconductor device having excellent thermal conductivity and electromagnetic wave absorbability.

  In recent years, electronic devices have been trending toward miniaturization, but the power consumption cannot be changed so much due to the variety of applications, and therefore heat radiation countermeasures in the devices have become more important.

  As a heat dissipation measure in the electronic devices described above, a heat dissipation plate, a heat pipe, a heat sink, or the like made of a metal material having a high thermal conductivity such as copper or aluminum is widely used. These heat dissipating parts having excellent thermal conductivity are arranged so as to be close to electronic parts such as a semiconductor package, which is a heat generating part in the electronic equipment, in order to achieve a heat radiation effect or temperature relaxation in the equipment. Further, these heat dissipating parts having excellent thermal conductivity are arranged from the electronic part as the heat generating part to a low temperature place.

  However, the heat generating part in the electronic device is an electronic component such as a semiconductor element having a high current density, and the high current density is considered to have a large electric field strength or magnetic field strength that can be a component of unnecessary radiation. For this reason, when a heat dissipating part made of metal is disposed in the vicinity of the electronic component, there is a problem that heat is absorbed and harmonic components of an electric signal flowing through the electronic component are picked up. Specifically, since the heat dissipating part is made of a metal material, it itself functions as a harmonic component antenna or acts as a transmission path for harmonic noise components.

In order to solve such a problem, in order to cut off the coupling of the magnetic field to the thermally conductive sheet, a technique containing a magnetic material has been developed.
For example, Patent Document 1 discloses an electromagnetic absorption heat conductive sheet used between a semiconductor such as a CPU and a heat sink, and by mixing a soft magnetic powder and a heat conductive filler in a silicone resin, the magnetic absorption effect of the soft magnetic powder, A technique for achieving both electromagnetic wave absorption and heat conduction characteristics by the heat conduction characteristics of the heat conduction filler is disclosed.
However, in the technique of Patent Document 1, although a certain effect is seen with respect to the electromagnetic wave absorption effect, the thermal conductivity in the vertical direction of the sheet is about 1.5 W / (m · K). Is not a sufficient property.

Patent Document 2 discloses an electromagnetic interference suppression sheet containing fibrous conductive carbon and carbonyl iron, and the volume ratio of the fibrous conductive carbon and carbonyl iron is 3 to 10:50 to 70. Thus, a technique for increasing electromagnetic wave absorption while ensuring sheet strength and flexibility is disclosed.
However, the technique of Patent Document 2 has a problem that if the fibrous conductive carbon exceeds 10% by volume, the dispersion becomes poor and a uniform sheet cannot be obtained, and sufficient consideration is not given to thermal conductivity. It was.

Furthermore, Patent Document 3 discloses a technique for suppressing electromagnetic noise and improving thermal conductivity by using an electromagnetic interference suppression sheet containing carbon fibers and magnetic powder in a resin matrix.
However, although the technique of Patent Document 3 provides good thermal conductivity, it does not provide a sufficient effect in terms of suppressing electromagnetic noise, and further improvement is desired in view of practical use. It was rare.

JP 2001-68312 A Japanese Patent No. 5103780 JP 2011-134755 A

  This invention is made | formed in view of this situation, Comprising: It aims at providing the electromagnetic wave absorption heat conductive sheet which has the outstanding heat conductivity and electromagnetic wave absorptivity, and its manufacturing method. Another object of the present invention is to provide a semiconductor device excellent in heat dissipation and electromagnetic wave suppression using such an electromagnetic wave absorbing heat conducting sheet.

  As a result of intensive studies to solve the above problems, the inventors of the present invention include a polymer matrix component, a fibrous thermal conductive filler, and magnetic metal powder, and the fibrous thermal conductivity. It has been found that by aligning the filler in one direction and adjusting the direction in which the filler is aligned, both thermal conductivity and electromagnetic wave absorption can be achieved at a higher level than before.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, a magnetic metal powder, and a fibrous heat conductive filler oriented in one direction.
With the above configuration, excellent thermal conductivity and electromagnetic wave absorption can be realized.
(2) The electromagnetic wave absorption heat according to (1) above, wherein the orientation direction of the fibrous thermally conductive filler is in the range of 60 ° to 90 ° with respect to the longitudinal direction of the sheet. Conductive sheet.
(3) The electromagnetic wave absorbing heat conductive sheet has a heat conductivity in the thickness direction of 5 W / (m · K) or more, a transmission absorption rate at 3 GHz of 30% or more, and a transmission absorption rate at 6 GHz of 70% or more. The electromagnetic wave-absorbing heat conductive sheet according to (1) above, wherein
(4) The electromagnetic wave absorption heat according to (1) above, wherein the orientation direction of the fibrous thermally conductive filler is in the range of more than 30 ° to 60 ° with respect to the longitudinal direction of the sheet. Conductive sheet.
(5) Thermal conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 2.7 W / (m · K) or more, transmission absorption at 3 GHz is 39% or more, and transmission absorption at 6 GHz is 70% or more. The electromagnetic wave absorbing heat conducting sheet according to (4) above, wherein
(6) The electromagnetic wave absorption heat conduction according to (1) above, wherein the orientation direction of the fibrous heat conductive filler is in the range of 0 ° to 30 ° with respect to the longitudinal direction of the sheet. Sheet.
(7) Thermal conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 1.5 W / (m · K) or more, transmission absorption at 3 GHz is 68% or more, and transmission absorption at 6 GHz is 70% or more. The electromagnetic wave absorbing heat conducting sheet according to (6) above, wherein
(8) The above-mentioned (1) to (7), characterized in that the content of the fibrous thermally conductive filler is 4 to 40% by volume and the content of the magnetic metal powder is 35 to 75% by volume. The electromagnetic wave absorbing heat conductive sheet according to any one of the above.
(9) The content of the fibrous thermally conductive filler is 5 to 30% by volume, and the content of the magnetic metal powder is 40 to 65% by volume, as described in (8) above Electromagnetic wave absorbing heat conductive sheet.
(10) The electromagnetic wave absorbing heat conductive sheet according to any one of (1) to (9), wherein the fibrous heat conductive filler is carbon fiber.
(11) The electromagnetic wave absorbing heat conductive sheet according to any one of (1) to (10), wherein the electromagnetic wave absorbing heat conductive sheet further includes an inorganic filler.
(12) a step of preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
The step of cutting the molded body for the sheet so as to have an angle of 0 ° to 90 ° with respect to the major axis direction of the oriented fibrous heat conductive filler, and producing an electromagnetic wave absorbing heat conductive sheet; ,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet characterized by including.
By the said structure, the electromagnetic wave absorption heat conductive sheet which has the outstanding heat conductivity and electromagnetic wave absorptivity can be provided.
(13) The step of orienting the fibrous thermally conductive filler is performed by extruding or press-fitting the sheet composition under a high shear force into a hollow mold,
The method for producing an electromagnetic wave absorbing heat conducting sheet as described in (12) above, wherein the step of producing the sheet compact is performed by thermosetting the polymer matrix component.
(14) preparing a sheet composition comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
The step of cutting the sheet molded body so as to have an angle of more than 60 ° to 90 ° with respect to the major axis direction of the oriented fibrous heat conductive filler to produce an electromagnetic wave absorbing heat conductive sheet When,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet as described in said (1), (4) or (7) characterized by including.
(15) a step of preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
The step of cutting the sheet molded body so as to have an angle of more than 30 ° to 60 ° with respect to the long axis direction of the oriented fibrous heat conductive filler to produce an electromagnetic wave absorbing heat conductive sheet When,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet as described in said (2), (5) or (8) characterized by including.
(16) preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
Cutting the molded body for the sheet so as to have an angle of 0 ° to 30 ° with respect to the major axis direction of the oriented fibrous heat conductive filler, and producing an electromagnetic wave absorbing heat conductive sheet; ,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet as described in said (3), (6) or (9) characterized by including.
(17) A semiconductor device comprising a heat source, a heat radiating member, and an electromagnetic wave absorbing heat conductive sheet sandwiched between the heat source and the heat radiating member,
The said electromagnetic wave absorption heat conductive sheet is an electromagnetic wave absorption heat conductive sheet of any one of said (1)-(13), The semiconductor device characterized by the above-mentioned.
With the above configuration, excellent heat dissipation and electromagnetic wave suppression can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the electromagnetic wave absorption heat conductive sheet which has the outstanding heat conductivity and electromagnetic wave absorptivity, and its manufacturing method. Moreover, it becomes possible to provide the semiconductor device excellent in heat dissipation and electromagnetic wave suppression using this electromagnetic wave absorption heat conductive sheet.

It is the figure which demonstrated typically one Embodiment of the electromagnetic wave absorption heat conductive sheet of this invention. It is the figure which showed typically the state at the time of cut | disconnecting the molded object for sheets in the process of producing the electromagnetic wave absorption heat conductive sheet of this invention. (A) It is the figure which showed typically one Embodiment of the semiconductor device of this invention, (b) It is the figure which showed typically other Embodiment of the semiconductor device of this invention. It is a figure which shows the transmission absorption factor (%) according to the frequency of Example 1, Comparative Example 4, and Comparative Example 1. It is a figure which shows the transmission absorption factor (%) according to the frequency of Example 4, the comparative example 4, and the comparative example 2. FIG. It is a figure which shows the transmission absorption factor (%) according to the frequency of Example 7, the comparative example 4, and the comparative example 3. FIG. It is the figure which showed the measurement system used for the measurement of a transmission absorption factor (%).

Hereinafter, an example of an embodiment of the present invention will be specifically described.
<Electromagnetic wave absorbing heat conductive sheet>
First, the electromagnetic wave absorbing heat conductive sheet of the present invention will be described.
The present invention is an electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, a fibrous heat conductive filler, and magnetic metal powder.

(Polymer matrix component)
The polymer matrix component contained in the electromagnetic wave absorbing heat conducting sheet of the present invention is a polymer component that becomes a base material of the electromagnetic wave absorbing heat conducting sheet. The type is not particularly limited, and a known polymer matrix component can be appropriately selected.
For example, one of the polymer matrix components is a thermosetting polymer.

  Examples of the thermosetting polymer include crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, silicone resin, polyurethane, polyimide silicone, thermosetting type. Examples include polyphenylene ether and thermosetting modified polyphenylene ether. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the crosslinked rubber include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, and fluorine. Examples thereof include rubber, urethane rubber, acrylic rubber, polyisobutylene rubber, and silicone rubber. These may be used individually by 1 type and may use 2 or more types together.

  Moreover, among these thermosetting polymers, it is preferable to use a silicone resin from the viewpoints of excellent moldability and weather resistance, and adhesion and followability to electronic components.

There is no restriction | limiting in particular as said silicone resin, The kind of silicone resin can be suitably selected according to the objective.
From the viewpoint of obtaining the above-described molding processability, weather resistance, adhesion, and the like, the silicone resin is preferably a silicone resin composed of a liquid silicone gel main ingredient and a curing agent. Examples of such a silicone resin include an addition reaction type liquid silicone resin, a heat vulcanization type millable type silicone resin using a peroxide for vulcanization, and the like. Among these, an addition reaction type liquid silicone resin is particularly preferable as a heat radiating member of an electronic device because adhesion between a heat generating surface of an electronic component and a heat sink surface is required.

  As the addition reaction type liquid silicone resin, it is preferable to use a two-component addition reaction type silicone resin having a polyorganosiloxane having a vinyl group as a main ingredient and a polyorganosiloxane having a Si-H group as a curing agent. .

  In addition, in the combination of the main agent of the liquid silicone gel and the curing agent, the blending ratio of the main agent and the curing agent is, as a mass ratio, main agent: curing agent = 35: 65 to 65:35. preferable.

  Further, the content of the polymer matrix component in the electromagnetic wave absorbing heat conductive sheet of the present invention is not particularly limited and can be appropriately selected according to the purpose, but the sheet formability, the sheet adhesion, etc. From the viewpoint of ensuring the above, it is preferably about 20% by volume to 50% by volume, and more preferably 30% by volume to 40% by volume.

(Thermal conductive filler)
The heat conductive filler contained in the electromagnetic wave absorbing heat conductive sheet of the present invention is a component for improving the heat conductivity of the sheet. About the kind of heat conductive filler, it is not specifically limited except being a fibrous heat conductive filler, A well-known heat conductive filler can be selected suitably.
FIG. 1 schematically shows a cross-sectional state of the electromagnetic wave absorbing heat conductive sheet of the present invention. As shown in FIG. 1, in the electromagnetic wave absorption heat conductive sheet 1 of the present invention, the fibrous heat conductive filler 12 is oriented in one direction (direction X in FIG. 1).

  As shown in FIG. 1, by orienting the fibrous thermal conductive filler 12, in the electromagnetic wave absorbing thermal conductive sheet 1, the fibrous thermal conductive filler 12 is regularly arranged, The magnetic metal powder 13 is regularly and uniformly dispersed. As a result, the effects of the fibrous thermal conductive filler 12 and the magnetic metal powder 13 can be more efficiently exhibited, so that thermal conductivity and electromagnetic wave absorption can be achieved at a high level.

  The “fibrous” of the fibrous thermal conductive filler in the present invention means a shape having a high aspect ratio (approximately 6 or more). Therefore, in the present invention, not only thermally conductive fillers such as fibers and rods, but also granular fillers having a high aspect ratio, flaky thermally conductive fillers, and the like are used as fibrous thermally conductive fillers. included.

Here, the type of the fibrous thermally conductive filler is not particularly limited as long as it is a fibrous and highly thermally conductive material. For example, metals such as silver, copper, and aluminum, alumina, and nitriding Examples thereof include ceramics such as aluminum, silicon carbide, and graphite, and carbon fibers.
Among these fibrous thermal conductive fillers, it is preferable to use carbon fibers from the viewpoint of obtaining higher thermal conductivity.
In addition, about the said heat conductive filler, you may use individually by 1 type, and may mix and use 2 or more types. In addition, when two or more kinds of thermally conductive fillers are used, both of them may be fibrous thermal conductive fillers, or the thermal conductivity of a different shape from the fibrous thermal conductive fillers. You may mix and use a filler.

  There is no restriction | limiting in particular about the kind of said carbon fiber, According to the objective, it can select suitably. For example, pitch-based, PAN-based, PBO fiber graphitized, synthesized by arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (saw medium chemical vapor deposition method), etc. Things can be used. Among these, carbon fibers obtained by graphitizing PBO fibers and pitch-based carbon fibers are more preferable because high thermal conductivity can be obtained.

  Moreover, the said carbon fiber can surface-treat the one part or all part as needed, and can use it. Examples of the surface treatment include oxidation treatment, nitriding treatment, nitration, sulfonation, or attaching a metal, a metal compound, an organic compound, or the like to the surface of a functional group or carbon fiber introduced to the surface by these treatments. The process etc. which are combined are mentioned. Examples of the functional group include a hydroxyl group, a carboxyl group, a carbonyl group, a nitro group, and an amino group.

Further, the average fiber length (average major axis length) of the carbon fiber is not particularly limited and can be appropriately selected. However, from the viewpoint of surely obtaining high thermal conductivity, it is in the range of 50 μm to 300 μm. Is preferable, more preferably in the range of 75 μm to 275 μm, and particularly preferably in the range of 90 μm to 250 μm.
Furthermore, the average fiber diameter (average minor axis length) of the carbon fiber is not particularly limited and may be appropriately selected. However, it is in the range of 4 μm to 20 μm from the viewpoint of surely obtaining high thermal conductivity. Preferably, it is in the range of 5 μm to 14 μm.

The aspect ratio (average major axis length / average minor axis length) of the carbon fiber is preferably 6 or more, more preferably 7 to 30 from the viewpoint of surely obtaining high thermal conductivity. . Even when the aspect ratio is small, an effect of improving thermal conductivity or the like can be seen, but an aspect ratio is preferably 6 or more because a large effect of improving characteristics cannot be obtained due to a decrease in orientation. On the other hand, when it exceeds 30, the dispersibility in the electromagnetic wave absorbing heat conductive sheet is lowered, so that there is a possibility that sufficient heat conductivity cannot be obtained.
Here, the average major axis length and the average minor axis length of the carbon fiber can be measured by, for example, a microscope, a scanning electron microscope (SEM), and the like, and the average can be calculated from a plurality of samples.

  The content of the fibrous heat conductive filler in the electromagnetic wave absorbing heat conductive sheet is not particularly limited and may be appropriately selected depending on the intended purpose, but is 4 vol% to 40 vol%. It is preferably 5% by volume to 30% by volume, more preferably 6% by volume to 20% by volume. If the content is less than 4% by volume, it may be difficult to obtain a sufficiently low heat resistance. If the content exceeds 40% by volume, the moldability of the heat conductive sheet and the fibrous heat conduction may be obtained. This may affect the orientation of the conductive filler.

Moreover, in the electromagnetic wave absorption heat conductive sheet 1 of this invention, as shown in FIG. 1, the said fibrous heat conductive filler 12 has orientated, and the orientation direction X is with respect to the longitudinal direction L of a sheet | seat. It is preferable to form a specific angle α. By adjusting the orientation direction X of the electromagnetic wave absorbing heat conducting sheet 1, the heat conducting property and / or electromagnetic wave absorbing property of the electromagnetic wave absorbing heat conducting sheet 1 of the present invention can be realized at a higher level.
Here, the longitudinal direction L of the sheet is the longitudinal direction of the electromagnetic wave absorbing heat conductive sheet 1 as the name suggests, and is the cut surface when the electromagnetic wave absorbing heat conductive sheet is cut out from the sheet molded body described later. It is a direction or a direction orthogonal to the cut surface. In addition, when the said electromagnetic wave absorption heat conductive sheet 1 is square, any may be a longitudinal direction, and when it is circular etc., let the longest diameter be the longitudinal direction L.
The orientation direction X of each fibrous thermal conductive filler 12 does not need to be completely coincident. In the present invention, if the orientation direction X is within ± 10 °, the orientation direction X is oriented in one direction. It can be said that.

For example, the orientation direction X of the fibrous thermally conductive filler 12 is in a range of 60 ° to 90 ° (angle α: a range of 60 ° to 90 °) with respect to the longitudinal direction L of the sheet. This is preferable because the thermal conductivity can be greatly improved.
When the orientation direction X of the fibrous heat conductive filler 12 is in the range of 60 ° to 90 ° with respect to the longitudinal direction L of the sheet, the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet Is 5 W / (m · K) or more, the transmission absorption rate at 3 GHz is 30% or more, and the transmission absorption rate at 6 GHz is 70% or more. The transmission absorptance is a value measured by a microstrip line method using an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm cut out in a disk shape of φ20 mm.

Further, the orientation direction X of the fibrous thermally conductive filler 12 is in the range of 30 ° to 60 ° with respect to the longitudinal direction L of the sheet (angle α: range of 30 ° to 60 °). This is preferable because the thermal conductivity and electromagnetic wave absorption can be improved in a well-balanced manner.
When the orientation direction X of the fibrous heat conductive filler 12 is in the range of more than 30 ° to 60 ° with respect to the longitudinal direction L of the sheet, the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet Is 2.7 W / (m · K) or more, the transmission absorption rate at 3 GHz is 39% or more, and the transmission absorption rate at 6 GHz is 70% or more. The transmission absorptance is a value measured by a microstrip line method using an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm cut out in a disk shape of φ20 mm.

For example, the orientation direction X of the fibrous thermal conductive filler 12 is in a range of 0 ° to 30 ° (angle α: a range of 0 ° to 30 °) with respect to the longitudinal direction L of the sheet. From the point that the electromagnetic wave absorbability can be greatly improved.
When the orientation direction X of the fibrous heat conductive filler 12 is in the range of 0 ° to 30 ° with respect to the longitudinal direction L of the sheet, the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 1.5W / (m · K) or more, transmission absorption at 3GHz is 68% or more, and transmission absorption at 6GHz is 70% or more. In this example, since the orientation direction X of the fibrous thermal conductive filler 12 is small, the thermal conductivity in the thickness direction is low, but since the thermal conductivity in the in-plane direction is high, it functions as a heat spreader. The transmission absorptance is a value measured by a microstrip line method using an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm cut out in a disk shape of φ20 mm.

  The method of changing the orientation direction X of the fibrous heat conductive filler 12 will be described in detail in the description of the method for producing an electromagnetic wave absorbing heat conductive sheet of the present invention. The orientation direction X of the fibrous thermal conductive filler 12 can be adjusted by adjusting the cut-out angle in the original sheet molded body with the thermal conductive filler 12 oriented.

(Inorganic filler)
The electromagnetic wave absorbing heat conductive sheet of the present invention preferably further contains an inorganic filler. This is because the heat conductivity of the electromagnetic wave absorbing heat conductive sheet can be further increased and the strength of the sheet can be improved.
The inorganic filler is not particularly limited with respect to shape, material, average particle diameter, and the like, and can be appropriately selected according to the purpose. Examples of the shape include a spherical shape, an elliptical spherical shape, a lump shape, a granular shape, a flat shape, and a needle shape. Among these, spherical and elliptical shapes are preferable from the viewpoint of filling properties, and spherical shapes are particularly preferable.

  Examples of the inorganic filler material include aluminum nitride (aluminum nitride: AlN), silica, alumina (aluminum oxide), boron nitride, titania, glass, zinc oxide, silicon carbide, silicon (silicon), silicon oxide, and aluminum oxide. And metal particles. These may be used individually by 1 type and may use 2 or more types together. Among these, alumina, boron nitride, aluminum nitride, zinc oxide, and silica are preferable, and alumina and aluminum nitride are particularly preferable from the viewpoint of thermal conductivity.

  The inorganic filler may be a surface-treated one. When the inorganic filler is treated with a coupling agent as the surface treatment, the dispersibility of the inorganic filler is improved and the flexibility of the heat conductive sheet is improved.

About the average particle diameter of the said inorganic filler, it can select suitably according to the kind etc. of an inorganic substance.
When the inorganic filler is alumina, the average particle size is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm, and particularly preferably 4 μm to 5 μm. When the average particle size is less than 1 μm, the viscosity increases and mixing may be difficult. On the other hand, when the average particle size exceeds 10 μm, the thermal resistance of the heat conductive sheet may increase.
Further, when the inorganic filler is aluminum nitride, the average particle size is preferably 0.3 μm to 6.0 μm, more preferably 0.3 μm to 2.0 μm, and particularly preferably 0.5 μm to 1.5 μm. preferable. If the average particle size is less than 0.3 μm, the viscosity may increase and mixing may be difficult, and if it exceeds 6.0 μm, the thermal resistance of the heat conductive sheet may increase.
In addition, the average particle diameter of the said inorganic filler can be measured with a particle size distribution meter and a scanning electron microscope (SEM), for example.

(Magnetic metal powder)
The magnetic metal powder contained in the electromagnetic wave absorbing heat conducting sheet of the present invention is a component for improving the electromagnetic wave absorbing property of the sheet.
About the kind of magnetic metal powder, it is not specifically limited except having electromagnetic wave absorptivity, A well-known magnetic metal powder can be selected suitably. For example, amorphous metal powder or crystalline metal powder can be used. Examples of amorphous metal powders include Fe-Si-B-Cr, Fe-Si-B, Co-Si-B, Co-Zr, Co-Nb, and Co-Ta. As the crystalline metal powder, for example, pure iron, Fe-based, Co-based, Ni-based, Fe-Ni-based, Fe-Co-based, Fe-Al-based, Fe-Si-based, Fe-Si-Al-based , Fe-Ni-Si-Al type and the like. Further, the crystalline metal powder is a microcrystalline metal obtained by adding a small amount of N (nitrogen), C (carbon), O (oxygen), B (boron), etc. to the crystalline metal powder. Powder may be used.
In addition, about the said magnetic metal powder, you may use what mixed the thing from which a material differs, or the thing from which an average particle diameter differs 2 or more types.

Moreover, about magnetic metal powder, it is preferable to adjust spherical shape, flat shape, etc. For example, in order to increase the filling property, it is preferable to use a magnetic metal powder having a particle size of several μm to several tens of μm and having a spherical shape. Such a magnetic metal powder can be produced by, for example, an atomizing method or a method of thermally decomposing metal carbonyl. The atomizing method has the advantage that a spherical powder is easy to make. The molten metal flows out from the nozzle, and a jet stream of air, water, inert gas, etc. is sprayed on the molten metal and solidified as droplets. It is a method of making a powder. When producing an amorphous magnetic metal powder by the atomizing method, it is preferable to set the cooling rate to about 10 ⁻⁶ (K / s) in order to prevent the molten metal from crystallizing.

  When the amorphous alloy powder is manufactured by the atomizing method described above, the surface of the amorphous alloy powder can be made smooth. Thus, when amorphous alloy powder with few surface unevenness | corrugations and a small specific surface area is used as magnetic metal powder, a filling property can be improved with respect to binder resin. Furthermore, the filling property can be further improved by performing the coupling treatment.

(Other ingredients)
The electromagnetic wave absorbing heat conductive sheet of the present invention may contain other components as appropriate in addition to the polymer matrix component, fibrous heat conductive filler, inorganic filler and magnetic metal powder described above. .
Examples of other components include a thixotropic agent, a dispersant, a curing accelerator, a retarder, a slightly tackifier, a plasticizer, a flame retardant, an antioxidant, a stabilizer, and a colorant.

  The thickness of the electromagnetic wave absorbing heat conductive sheet of the present invention is not particularly limited and can be appropriately changed depending on the place where the sheet is used. For example, considering the adhesion and strength of the sheet, the thickness is in the range of 0.2 mm to 5 mm. can do.

<Method for producing electromagnetic wave absorbing heat conductive sheet>
Next, the manufacturing method of the electromagnetic wave absorption heat conductive sheet of this invention is demonstrated.
The method for producing an electromagnetic wave absorbing heat conductive sheet of the present invention comprises a step of preparing a composition for a sheet comprising a polymer matrix component, a fibrous heat conductive filler, and a magnetic metal powder (sheet composition preparing step). )When,
A step of orienting the fibrous thermally conductive filler (filler orientation step);
In a state where the orientation of the fibrous heat conductive filler is maintained, the polymer matrix component is cured to produce a sheet molded body (sheet molded body producing process);
A step of cutting the sheet molded body so as to have an angle of 0 ° to 90 ° with respect to the major axis direction of the oriented fibrous heat conductive filler to produce an electromagnetic wave absorbing heat conductive sheet ( Electromagnetic wave absorbing heat conductive sheet manufacturing process),
It is characterized by including.
By passing through each said process, the electromagnetic wave absorption heat conductive sheet of this invention can be obtained. About the obtained electromagnetic wave absorption heat conductive sheet, as above-mentioned, it is excellent in thermal conductivity and electromagnetic wave absorptivity.

(Sheet composition preparation process)
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of this invention includes the composition preparation process for sheets.
In this sheet composition preparation step, the above-described polymer matrix component, fibrous thermal conductive filler and magnetic metal powder, and further, an inorganic filler and / or other components are blended to prepare a sheet composition. . The procedure for blending and preparing each component is not particularly limited. For example, the polymer matrix component includes a polymer matrix component, a fibrous thermal conductive filler, an inorganic filler, a magnetic metal powder, and other components. Is added and mixed to prepare a sheet composition.

(Filler orientation process)
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of this invention includes the composition preparation process for sheets.
The method for orienting the fibrous heat conductive filler is not particularly limited as long as it is a means capable of orienting in one direction.

  As a method for orienting the fibrous thermally conductive filler in one direction, it may be performed by extruding or press-fitting the sheet composition under a high shear force into a hollow mold. It is done. By this method, the fibrous heat conductive filler can be oriented relatively easily, and the orientation of the fibrous heat conductive filler is the same (within ± 10 °).

Specific examples of the method for extruding or press-fitting the sheet composition into the hollow mold described above under a high shear force include an extrusion molding method and a mold molding method.
When extruding the sheet composition from a die in the extrusion molding method, or when press-fitting the thermally conductive resin composition into the mold in the mold molding method, the binder resin flows, and its flow direction The carbon fibers are oriented along. At this time, if a slit is attached to the tip of the die, the carbon fibers are more easily oriented.

  The size and shape of the molded body (block-shaped molded body) can be determined according to the required size of the electromagnetic wave absorbing heat conductive sheet. For example, a rectangular parallelepiped having a vertical size of 0.5 cm to 15 cm and a horizontal size of 0.5 cm to 15 cm can be mentioned. The length of the rectangular parallelepiped may be determined as necessary.

(Sheet compact manufacturing process)
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of this invention includes the molded object preparation process for sheets.
Here, the said molded object for sheets means the sheet | seat (molded object) used as the origin of the electromagnetic wave absorption heat conductive sheet of this invention obtained by cut | disconnecting to a predetermined size. The molded body for the sheet is produced by curing the polymer matrix component while maintaining the orientation state of the fibrous thermal conductive filler performed in the filler orientation step described above.

  The method and conditions for curing the polymer matrix component can be changed according to the type of the polymer matrix component. For example, when the polymer matrix component is a thermosetting resin, the curing temperature in thermosetting can be adjusted. Furthermore, when the thermosetting resin contains a main component of a liquid silicone gel and a curing agent, curing is preferably performed at a curing temperature of 80 ° C to 120 ° C. Moreover, there is no restriction | limiting in particular as hardening time in thermosetting, However It can be set as 1 hour-10 hours.

(Electromagnetic wave absorbing heat conductive sheet manufacturing process)
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of this invention includes an electromagnetic wave absorption heat conductive sheet preparation process.
In the electromagnetic wave absorbing heat conductive sheet manufacturing step, as shown in FIG. 2, the angle β is 0 ° to 90 ° with respect to the major axis direction J of the oriented fibrous heat conductive filler 12. The sheet molded body is cut.

  As shown in FIG. 2, the sheet molded body 10 obtained in the sheet molded body manufacturing step is in a state in which the major axis of the fibrous thermal conductive filler 12 is oriented in a certain direction J. (FIG. 2 shows a state in which the metal magnetic powder 13 is omitted for easy viewing). The electromagnetic wave absorbing heat conducting sheet 1 shown in FIG. 1 can be obtained by cutting into a sheet shape with a constant cutting angle β with respect to the major axis direction J of the carbon fiber 12.

In addition, about the cutting | disconnection angle (beta) with respect to the major axis direction J of the said carbon fiber 12, it adjusts suitably according to the orientation direction X (angle (alpha) with respect to a sheet longitudinal direction) of the carbon fiber 12 in the obtained electromagnetic wave absorption heat conductive sheet 1. be able to.
For example, when the orientation direction X of the carbon fiber 12 in the electromagnetic wave absorbing heat conducting sheet 1 is 30 ° (α = 30 °) with respect to the longitudinal direction of the sheet, the carbon fiber 12 is cut in the major axis direction J. The angle β may be 30 °.

Moreover, about the cutting | disconnection of the said molded object for sheets, it is performed using a slicing apparatus.
The slicing device is not particularly limited as long as it is a means capable of cutting the sheet molded body, and a known slicing device can be appropriately used. For example, an ultrasonic cutter, a planer (鉋), or the like can be used.

(Pressing process)
The method for producing an electromagnetic wave absorbing heat conductive sheet of the present invention further includes smoothing the surface of the electromagnetic wave absorbing heat conductive sheet, increasing the adhesion, and reducing the interfacial contact resistance at light loads. A step of pressing (a pressing step) can be included.
About the said press, it can carry out using a pair of press apparatus which consists of a flat board and a press head with the flat surface, for example. Moreover, you may press using a pinch roll.

  The pressure at the time of pressing is not particularly limited and can be appropriately selected according to the purpose. However, if it is too low, the thermal resistance tends to be the same as when not pressing, and if it is too high, the sheet is stretched. Since there exists a tendency, it is preferable to set it as the pressure range of 0.1MPa-100MPa, and it is more preferable to set it as the pressure range of 0.5MPa-95MPa.

<Semiconductor device>
Next, the semiconductor device of the present invention will be described.
The semiconductor device of the present invention is a semiconductor device comprising a heat source, a heat radiating member, and an electromagnetic wave absorbing heat conductive sheet sandwiched between the heat source and the heat radiating member, wherein the electromagnetic wave absorbing heat conductive sheet is described above. It is an electromagnetic wave absorption heat conductive sheet of the present invention.
By using the electromagnetic wave absorbing heat conductive sheet of the present invention, the obtained semiconductor device is excellent in electromagnetic wave suppression effect while having high heat dissipation.

  Here, the heat source is not particularly limited as long as it generates heat in the semiconductor device. For example, an electronic part etc. are mentioned, As this electronic part, CPU, MPU, a graphic arithmetic element, an image sensor etc. are mentioned.

  The heat radiating member conducts heat generated from the heat source and dissipates it to the outside. For example, a radiator, a cooler, a heat sink, a heat spreader, a die pad, a printed board, a cooling fan, a Peltier element, a heat pipe, a metal cover, a housing, and the like can be given.

An example of the semiconductor device of the present invention will be described with reference to FIGS.
FIG. 3A is a schematic cross-sectional view showing an example of the semiconductor device of the present invention. The semiconductor device includes an electromagnetic wave absorbing heat conductive sheet 1, a heat spreader 2, an electronic component 3, a heat sink 5, and a wiring substrate 6.

  The electromagnetic wave absorbing heat conducting sheet 1 absorbs unnecessary electromagnetic waves generated in the electronic component 3 and electromagnetic waves radiated from other components and dissipates heat generated by the electronic component 3, as shown in FIG. As shown, the heat spreader 2 is fixed to the main surface 2 a facing the electronic component 3 and is sandwiched between the electronic component 3 and the heat spreader 2. Further, the electromagnetic wave absorbing heat conducting sheet 1 is sandwiched between the heat spreader 2 and the heat sink 5.

  The heat spreader 2 is formed in, for example, a rectangular plate shape, and includes a main surface 2a facing the electronic component 3 and a side wall 2b erected along the outer periphery of the main surface 2a. The heat spreader 2 is provided with the electromagnetic wave absorbing heat conductive sheet 1 on the main surface 2a surrounded by the side wall 2b, and the heat sink 5 is provided on the other surface 2c opposite to the main surface 2a via the electromagnetic wave absorbing heat conductive sheet 1. It is done. The heat spreader 2 has a higher thermal conductivity, so that the thermal resistance is reduced and the heat of the electronic component 3 such as a semiconductor element is efficiently absorbed. Therefore, the heat spreader 2 is formed using, for example, copper or aluminum having good thermal conductivity. be able to.

  The electronic component 3 is a semiconductor package such as a BGA, for example, and is mounted on the wiring board 6. Further, the heat spreader 2 also has the front end surface of the side wall 2b mounted on the wiring board 6, and thereby surrounds the electronic component 3 at a predetermined distance by the side wall 2b.

  The electromagnetic wave absorbing heat conductive sheet 1 is adhered to the main surface 2 a of the heat spreader 2, thereby absorbing heat generated by the electronic component 3 and dissipating heat from the heat sink 5. The adhesion between the heat spreader 2 and the electromagnetic wave absorbing heat conducting sheet 1 can be performed by the adhesive force of the electromagnetic wave absorbing heat conducting sheet 1 itself.

FIG. 3B is a schematic cross-sectional view showing another example of the semiconductor device of the present invention.
The semiconductor device includes an electromagnetic wave absorbing heat conductive sheet 1, a heat spreader 2, an electronic component 3, a heat sink 5, and a wiring substrate 6.

  The electromagnetic wave absorbing heat conducting sheet 1 absorbs unnecessary electromagnetic waves generated in the electronic component 3 and electromagnetic waves radiated from other components, and dissipates heat generated by the electronic component 3, as shown in FIG. As shown, the electronic component 3 is fixed to the upper surface 3 a and is sandwiched between the electronic component 3 and the heat spreader 2.

  Next, the present invention will be specifically described based on examples. However, the present invention is not limited to the following examples.

Example 1
In Example 1, a two-component addition reaction type liquid silicone resin, Fe-Si-B-Cr amorphous magnetic particles having an average particle diameter of 5 μm, and pitch-based carbon fibers having an average fiber length of 200 μm (“thermally conductive fiber”) (Manufactured by Nippon Graphite Fiber Co., Ltd.), in a volume ratio, two-component addition reaction type liquid silicone resin: amorphous magnetic particles: pitch-based carbon fiber = 35 vol%: 53 vol%: 12 vol%, A silicone resin composition (sheet composition) was prepared.
The two-component addition-reaction type liquid silicone resin is a mixture of silicone A liquid (main agent) and silicone B liquid (curing agent) in a ratio of 19:16. The obtained silicone resin composition was extruded into a rectangular parallelepiped mold 30 mm × 30 mm having a PET film peel-treated on the inner wall to mold a silicone molded body. The obtained silicone molded body was cured in an oven at 100 ° C. for 6 hours to obtain a cured silicone product.
Next, the obtained cured silicone was cut with an ultrasonic cutter perpendicular to the long axis of the oriented carbon fiber, that is, with a cutting angle β: 90 ° (orientation angle α: 90 °), and the thickness was 1 mm. A sample of an electromagnetic wave absorbing heat conductive sheet was obtained. The slice speed of the ultrasonic cutter was 50 mm per second. The ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 μm.

(Example 2)
In Example 2, the cured silicone product was cut at a cutting angle β: 75 ° (orientation angle α: 75 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

(Example 3)
In Example 3, the cured silicone product was cut at a cutting angle β: 60 ° (orientation angle α: 60 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

Example 4
In Example 4, the cured silicone product was cut at a cutting angle β: 45 ° (orientation angle α: 45 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

(Example 5)
In Example 5, the above silicone cured product was cut at a cutting angle β: 30 ° (orientation angle α: 30 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

(Example 6)
In Example 6, the cured silicone product was cut at a cutting angle β: 15 ° (orientation angle α: 15 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

(Example 7)
In Example 7, the cured silicone product was cut at a cutting angle β: 0 ° (orientation angle α: 0 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The blending and other steps are the same as in Example 1.

(Comparative Example 1)
In Comparative Example 1, the cured silicone was cut at a cutting angle of 90 ° (orientation angle α: 90 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. In this example, silica powder of 3 to 5 μm is used instead of the metal magnetic powder, and the mixing is in a volume ratio, and the two-component addition reaction type liquid silicone resin: silica powder: pitch-based carbon fiber = 35 vol%: 53 vol% : Dispersed to 12 vol% to prepare a silicone resin composition (sheet composition). The other steps are the same as in Example 1.

(Comparative Example 2)
In Comparative Example 2, the cured silicone product was cut at a cutting angle of 45 ° (orientation angle α: 45 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. In this example, silica powder of 3 to 5 μm is used instead of the metal magnetic powder, and the mixing is in a volume ratio, and the two-component addition reaction type liquid silicone resin: silica powder: pitch-based carbon fiber = 35 vol%: 53 vol% : Dispersed to 12 vol% to prepare a silicone resin composition (sheet composition). The other steps are the same as in Example 1.

(Comparative Example 3)
In Comparative Example 3, the silicone cured product was cut at a cutting angle of 0 ° (orientation angle α: 0 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. In this example, silica powder of 3 to 5 μm is used instead of the metal magnetic powder, and the mixing is in a volume ratio, and the two-component addition reaction type liquid silicone resin: silica powder: pitch-based carbon fiber = 35 vol%: 53 vol% : Dispersed to 12 vol% to prepare a silicone resin composition (sheet composition). The other steps are the same as in Example 1.

(Comparative Example 4)
In Comparative Example 4, the silicone cured product was cut at a cutting angle of 0 ° (orientation angle α: 0 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. In this example, carbon fiber is not included, it is composed only of silicone resin and metal magnetic powder, and the mixture is dispersed so that the volume ratio is two-component addition reaction type liquid silicone resin: metal magnetic powder = 47 vol%: 53 vol% Thus, a silicone resin composition (sheet composition) was prepared. The other steps are the same as in Example 1.

(Comparative Example 5)
In Comparative Example 5, the silicone molded body was not molded by being extruded into a mold. Therefore, the carbon fiber in the obtained electromagnetic wave absorption heat conductive sheet is not oriented in one direction. The other steps are the same as in Example 1.

(Comparative Example 6)
In Comparative Example 6, the silicone molded body was not molded by being extruded into a mold. Therefore, the carbon fiber in the obtained electromagnetic wave absorption heat conductive sheet is not oriented in one direction. Further, in this example, silica powder of 3 to 5 μm is used instead of the metal magnetic powder, and the composition is in a volume ratio, and the two-component addition reaction type liquid silicone resin: silica powder: pitch-based carbon fiber = 35 vol%: A silicone resin composition (sheet composition) was prepared by dispersing 53 vol%: 12 vol%. The other steps are the same as in Example 1.

(Examples 8 to 11)
In Examples 8 to 11, the cured silicone product was cut at a cutting angle of 90 ° (orientation angle α: 90 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The composition is in a volume ratio such that two-component addition reaction type liquid silicone resin: amorphous magnetic particles: pitch-based carbon fiber has a ratio as shown in Table 2. The other steps are the same as in Example 1.

(Examples 12 to 15)
In Examples 12 to 15, the above cured silicone was cut at a cutting angle of 45 ° (orientation angle α: 45 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The composition is in a volume ratio such that two-component addition reaction type liquid silicone resin: amorphous magnetic particles: pitch-based carbon fiber has a ratio as shown in Table 2. The other steps are the same as in Example 1.

(Examples 16 to 19)
In Examples 16 to 19, the silicone cured product was cut at a cutting angle of 0 ° (orientation angle α: 0 °) to obtain a sample of an electromagnetic wave absorbing heat conductive sheet having a thickness of 1 mm. The composition is in a volume ratio such that two-component addition reaction type liquid silicone resin: amorphous magnetic particles: pitch-based carbon fiber has a ratio as shown in Table 2. The other steps are the same as in Example 1.

(Evaluation)
The following evaluation was performed about each sample of the obtained electromagnetic wave absorption heat conductive sheet. The evaluation results are shown in Table 1.

(1) Thermal conductivity Each sample was cut into a disk shape of φ20 mm and the thermal resistance was measured. The thermal resistance of each electromagnetic wave absorbing heat conductive sheet was measured in accordance with ASTM D 5470 using a thermal conductivity measuring device (manufactured by Sony Corporation) with a load of 1.5 kgf / cm ² . The thermal conductivity was calculated from this value. The results are shown in Tables 1 and 2.

(2) Transmission absorption rate
The microstrip line method described in IEC62333-2 was used. The measurement system 100 uses the one shown in FIG. 7 and measures the reflected signal (S11) and the transmitted signal (S21) by the network analyzer 110. The microstrip line 112 is formed on the surface of a 100 × 100 × 1.6 mm dielectric substrate (backside copper) with a width of 4 mm, and is adjusted to have a characteristic impedance of 50Ω. Each sample 111 was cut out into a disk shape of φ20 mm, attached to the center of the microstrip line, S11 and S21 were measured, and the absorption rate was calculated.
Under the present circumstances, the loss when not installing an electromagnetic wave absorption heat conductive sheet was deducted, and it calculated as a value only of the effect of an electromagnetic wave absorption heat conductive sheet. Values at 1, 3, and 6 GHz were extracted and shown in Tables 1 and 2.
Moreover, about Example 1, Comparative Example 4 and Comparative Example 1, what showed the transmission absorptivity (%) according to the frequency is shown in FIG. 4, and about Example 4, Comparative Example 4 and Comparative Example 2, the frequency is shown. FIG. 5 shows the corresponding transmission absorption rate (%), and FIG. 6 shows the transmission absorption rate (%) corresponding to the frequency for Example 7, Comparative Example 4 and Comparative Example 3. It was.

From the results in Table 1, in Examples 1 and 2, the thermal conductivity is as high as 6 W / (m · K) or more, and the transmission absorption rate is 35% or more especially in the 3 GHz band, and 76% or more in the 6 GHz band. Excellent characteristics in high frequency range. In Examples 3 and 4, the thermal conductivity is relatively high at 3.8 W / (m · K) or higher, and the transmission absorption rate is about 40% or higher in the 3 GHz band and 75% or higher in the 6 GHz band, which is a slightly low frequency range. The characteristics are improved. In Examples 5 to 7, although the thermal conductivity is slightly lower as 2.7 to 1.5 W / (m · K), the transmission absorptance is less than 5% even in the 1 GHz band, and less than 70% in the high frequency region than the 3 GHz band. It was found that it exhibits particularly excellent characteristics.
As described above, in Examples 1 to 7, excellent thermal conductivity and transmission absorptance can be obtained, and furthermore, an appropriate balance between the thermal conductivity and the transmission absorptivity can be set by the orientation angle of the carbon fiber. all right.
On the other hand, looking at the comparative example, in Comparative Examples 1 and 2, which are composed of only carbon fiber and silica without including a magnetic material, the transmission absorptance is extremely small, and in Comparative Example 3, both the thermal conductivity and the transmission absorptivity are small. I found out that In the comparative example 4 comprised only with the magnetic body, it turned out that thermal conductivity is remarkably small. Further, in Comparative Examples 5 and 6 in which the carbon fiber orientation treatment is not performed, the thermal conductivity is higher than that in Example 1 and Comparative Example 1 which are the same conditions except that there is no orientation of the carbon fiber or the heat conductive filler. It turned out to be inferior.

  Table 2 shows the characteristic values of thermal conductivity and transmission absorptivity when the content ratio of carbon fiber and magnetic material is changed at carbon fiber orientation angles of 90 °, 45 °, and 0 °. It was found that by adjusting the content ratio of the carbon fiber and the magnetic material together with the orientation angle of the fiber, various characteristic values of thermal conductivity and transmission absorption rate can be set.

  Moreover, in FIGS. 4-6, although the frequency characteristic of the transmission absorptance was compared, in any orientation angle | corner (alpha) of carbon fiber, compared with the comparative example comprised by the carbon fiber, and the comparative example comprised by the magnetic body, It was found that the example in which both the carbon fiber and the magnetic material were mixed had a better transmission absorption rate due to the synergistic effect.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the electromagnetic wave absorption heat conductive sheet which has the outstanding heat conductivity and electromagnetic wave absorptivity, and its manufacturing method. Moreover, it becomes possible to provide the semiconductor device excellent in heat dissipation and electromagnetic wave suppression using this electromagnetic wave absorption heat conductive sheet.

DESCRIPTION OF SYMBOLS 1 Electromagnetic wave absorption heat conductive sheet 2 Heat spreader 2a Main surface 2b Side wall 2c Other surface 3 Electronic component 3a Upper surface 5 Heat sink 6 Wiring board 10 Electromagnetic wave absorption heat conductive sheet 11 Polymer matrix component 12 Carbon fiber 13 Magnetic metal powder 100 Measurement system 110 Network Analyzer 111 Electromagnetic wave absorbing heat conductive sheet sample 112 Microstrip line

Claims (17)

An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 60 ° to 90 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 5 W / (M · K) or more, and an electromagnetic wave absorption heat conduction sheet characterized by having a transmission absorption rate at 1 GHz of 3.6% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 30 ° to 60 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 2.7 W. / (M · K) or more, and an electromagnetic wave absorption heat conduction sheet characterized by having a transmission absorption rate at 1 GHz of 3.8% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in a range of 0 ° to 30 ° with respect to the extending direction of the sheet surface, and the electromagnetic conductivity heat conductive sheet has a heat conductivity in the thickness direction of 1.5 W / An electromagnetic wave-absorbing heat conductive sheet characterized by having a transmission absorption rate at 1 GHz of not less than (m · K) and 4.8% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 60 ° to 90 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 5 W / (M · K) or more, an electromagnetic wave absorbing heat conductive sheet characterized by having a transmission absorptivity at 3 GHz of 30% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 30 ° to 60 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 2.7 W. / (M · K) or more and a transmission absorption rate at 3 GHz of 39% or more, an electromagnetic wave absorbing heat conducting sheet. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in a range of 0 ° to 30 ° with respect to the extending direction of the sheet surface, and the electromagnetic conductivity heat conductive sheet has a heat conductivity in the thickness direction of 1.5 W / (M · K) or more, an electromagnetic wave absorbing heat conducting sheet characterized by having a transmission absorptivity at 3 GHz of 68% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 60 ° to 90 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 5 W / (M · K) or more and an electromagnetic wave absorption heat conduction sheet characterized by having a transmission absorption rate at 6 GHz of 70% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in the range of more than 30 ° to 60 ° with respect to the extending direction of the sheet surface, and the heat conductivity in the thickness direction of the electromagnetic wave absorbing heat conductive sheet is 2.7 W. / (M · K) or more and an electromagnetic wave absorption heat conduction sheet characterized by having a transmission absorption rate at 6 GHz of 70% or more. An electromagnetic wave absorbing heat conductive sheet comprising a polymer matrix component, magnetic metal powder, and a fibrous heat conductive filler,
The fibrous heat conductive filler is oriented in a range of 0 ° to 30 ° with respect to the extending direction of the sheet surface, and the electromagnetic conductivity heat conductive sheet has a heat conductivity in the thickness direction of 1.5 W / (M · K) or more and an electromagnetic wave absorption heat conduction sheet characterized by having a transmission absorption rate at 6 GHz of 70% or more.   The content of the fibrous heat-conductive filler is 4 to 40% by volume, and the content of the magnetic metal powder is 35 to 75% by volume. The electromagnetic wave absorbing heat conductive sheet according to 1.   11. The electromagnetic wave absorbing heat conduction according to claim 10, wherein a content of the fibrous heat conductive filler is 5 to 30% by volume and a content of the magnetic metal powder is 40 to 65% by volume. Sheet.   The electromagnetically absorbing heat conductive sheet according to any one of claims 1 to 11, wherein the fibrous heat conductive filler is carbon fiber.   The electromagnetic wave absorbing heat conductive sheet according to any one of claims 1 to 12, wherein the electromagnetic wave absorbing heat conductive sheet further includes an inorganic filler. Preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
The step of cutting the sheet molded body so as to have an angle of more than 60 ° to 90 ° with respect to the major axis direction of the oriented fibrous heat conductive filler to produce an electromagnetic wave absorbing heat conductive sheet When,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of Claim 1, 4 or 7 characterized by the above-mentioned. Preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
The step of cutting the sheet molded body so as to have an angle of more than 30 ° to 60 ° with respect to the long axis direction of the oriented fibrous heat conductive filler to produce an electromagnetic wave absorbing heat conductive sheet When,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of Claim 2, 5 or 8 characterized by the above-mentioned. Preparing a composition for a sheet comprising a polymer matrix component, a fibrous thermal conductive filler, and a magnetic metal powder;
Orienting the fibrous thermally conductive filler;
In a state where the orientation of the fibrous thermally conductive filler is maintained, the polymer matrix component is cured, and a molded article for a sheet is produced.
Cutting the molded body for the sheet so as to have an angle of 0 ° to 30 ° with respect to the major axis direction of the oriented fibrous heat conductive filler, and producing an electromagnetic wave absorbing heat conductive sheet; ,
The manufacturing method of the electromagnetic wave absorption heat conductive sheet of Claim 3, 6, or 9 characterized by the above-mentioned. A semiconductor device comprising a heat source, a heat radiating member, and an electromagnetic wave absorbing heat conducting sheet sandwiched between the heat source and the heat radiating member,
The semiconductor device according to claim 1, wherein the electromagnetic wave absorbing heat conducting sheet is the electromagnetic wave absorbing heat conducting sheet according to claim 1.

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