JPWO2019230607A1 - Electronic equipment and electromagnetic radiation shielding heat radiation sheet - Google Patents

Abstract

One aspect of the present invention includes an electronic component, an electromagnetic wave shielding heat dissipation sheet, and a housing that accommodates the electronic component and the electromagnetic wave shielding heat dissipation sheet, wherein the electromagnetic wave shielding heat dissipation sheet is a first heat conductive resin. A layer, a conductive layer, and a second heat conductive resin layer in this order, and the first heat conductive resin layer contacts the electronic component, and the second heat conductive resin layer is attached to the housing. An electronic device that is arranged in contact.

Description

The present invention relates to an electronic device and an electromagnetic wave radiation sheet.

With the miniaturization and weight reduction of electronic parts, high density mounting of electronic parts is advancing, and in order to prevent malfunctions and suppress the effects on the human body, it is necessary to shield the electromagnetic waves generated from electronic parts (electromagnetic wave shield). The need is growing. Conventionally, as a method of electromagnetic wave shielding, a method of sealing an electronic component in a metal casing has been adopted, but this method requires a space distance between the electronic component and the casing to ensure insulation. This is an obstacle to miniaturization of electronic devices. On the other hand, a sheet-shaped electromagnetic wave shield material has been proposed as an electromagnetic wave shield material that replaces the metal casing (for example, Patent Document 1).

JP, 2014-45047, A

On the other hand, in the electronic device as described above, it is also important to radiate heat to the outside of the electronic device in order to prevent failure of the electronic device due to heat generated from the electronic component. However, the sheet-shaped electromagnetic wave shield material as described in Patent Document 1 does not have a heat radiation property, and it is necessary to separately provide a heat radiation member in the electronic device for heat radiation. In this case, since the number of members increases, it becomes difficult to downsize the electronic device.

Therefore, an object of the present invention is to reduce the size of an electronic device while imparting electromagnetic wave shielding properties and heat dissipation properties to the electronic device.

As a result of intensive studies, the present inventors have used a sheet in which a heat conductive resin layer is laminated on both surfaces of a conductive layer, and one heat conductive resin layer is an electronic component and the other heat conductive resin layer is a casing. It has been found that by arranging them so that they contact each other, it is possible to reduce the size of the electronic device while imparting electromagnetic wave shielding properties and heat dissipation properties to the electronic device.

That is, the present invention can provide the following in some aspects.
[1] An electronic component, an electromagnetic wave shielding heat dissipation sheet, and a housing that accommodates the electronic component and the electromagnetic wave shielding heat dissipation sheet, wherein the electromagnetic wave shielding heat dissipation sheet includes a first heat conductive resin layer and a conductive material. A layer and a second heat conductive resin layer in this order, and the first heat conductive resin layer contacts the electronic component and the second heat conductive resin layer contacts the housing. The electronic devices that are located.
[2] The electronic device according to [1], wherein the conductive layer is formed of a metal foil or a metal mesh.
[3] The electronic device according to [1] or [2], wherein the conductive layer contains at least one selected from the group consisting of aluminum, copper, silver and gold.
[4] The electronic device according to any one of [1] to [3], wherein the first thermally conductive resin layer and the second thermally conductive resin layer each contain a silicone resin and a thermally conductive filler.
[5] The electronic device according to [4], wherein the content of the thermally conductive filler is 40 to 85% by volume with respect to each of the first thermally conductive resin layer and the second thermally conductive resin layer. ..
[6] The electronic device according to any one of [1] to [5], wherein a plurality of cuts are formed in at least one of the first thermally conductive resin layer and the second thermally conductive resin layer.
[7] An electromagnetic wave shielding heat dissipation sheet including a first heat conductive resin layer, a conductive layer, and a second heat conductive resin layer in this order.
[8] The electromagnetic wave shielding heat dissipation sheet according to [7], wherein the conductive layer is formed of a metal foil or a metal mesh.
[9] The electromagnetic wave radiation sheet according to [7] or [8], wherein the conductive layer contains at least one selected from the group consisting of aluminum, copper, silver and gold.
[10] The electromagnetic wave shielding property according to any one of [7] to [9], wherein the first thermally conductive resin layer and the second thermally conductive resin layer each contain a silicone resin and a thermally conductive filler. Heat dissipation sheet.
[11] The electromagnetic wave shield according to [10], wherein the content of the heat conductive filler is 40 to 85% by volume with respect to each of the first heat conductive resin layer and the second heat conductive resin layer. Heat dissipation sheet.
[12] The electromagnetic radiation shielding heat radiation according to any one of [7] to [11], wherein a plurality of cuts are formed in at least one of the first heat conductive resin layer and the second heat conductive resin layer. Sheet.

According to the present invention, it is possible to reduce the size of an electronic device while imparting electromagnetic wave shielding properties and heat dissipation properties to the electronic device.

It is a schematic cross section which shows the electronic device which concerns on one Embodiment. It is a perspective view showing an electromagnetic wave shielding heat dissipation sheet concerning one embodiment. It is a perspective view which shows the electromagnetic wave shielding heat dissipation sheet which concerns on other one Embodiment. It is a schematic cross section which shows the conventional electronic device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an electronic device according to an embodiment. As shown in FIG. 1, an electronic device 1 according to an embodiment includes a substrate 2, an electronic component 4 provided on the substrate 2 via a plurality of solders 3, an electromagnetic wave shielding heat dissipation sheet (hereinafter, simply referred to as " It is also provided with a heat dissipation sheet) 5 and a housing 6 for housing these.

The substrate 2 may be, for example, a printed circuit board or the like. The electronic component 4 may be, for example, an LSI (large-scale integrated circuit), an IC (integrated circuit), a semiconductor package, or the like. The solder 3 electrically connects the wiring on the substrate 2 and the electronic component 4 to each other. The solder 3 may be, for example, a solder ball, or may be formed by soldering with the pins of the electronic component 4 inserted in the substrate 2.

The housing 6 is, for example, a hollow box-shaped box. The housing 6 may be made of metal or resin. The housing 6 may be, for example, a metal housing having an electromagnetic wave shielding property or a resin housing having no electromagnetic wave shielding property. Since the electronic device 1 includes the heat dissipation sheet 5 having an electromagnetic wave shielding property, even if the housing 6 does not have an electromagnetic wave shielding property (for example, a resin housing), it is generated from the electronic component 4. Electromagnetic waves are suitably shielded by the heat dissipation sheet 5, and are less likely to leak to the outside of the electronic device 1.

The heat dissipation sheet 5 includes a conductive layer (conductive base material) 7 and heat conductive resin layers 8 and 9 laminated on both surfaces of the conductive layer 7. FIG. 2 is a perspective view showing an embodiment of the heat dissipation sheet 5. As shown in FIG. 2, the heat dissipation sheet 5A according to the embodiment includes a first heat conductive resin layer 8A, a conductive layer 7, and a second heat conductive resin layer 9 in this order. The first heat conductive resin layer 8A, the conductive layer 7, and the second heat conductive resin layer 9 have substantially the same planar shape (for example, rectangular shape), and the end surfaces of the layers are aligned with each other. The heat dissipation sheet 5 is formed by stacking layers.

In the electronic device 1, the heat dissipation sheet 5 is arranged so that the first thermally conductive resin layer 8 contacts the electronic component 4 and the second thermally conductive resin layer 9 contacts the housing 6. .. Thereby, the heat generated in the electronic component 4 can be radiated to the outside through the housing 6.

The conductive layer 7 is preferably made of metal foil or metal mesh. The conductive layer 7 contains at least one selected from the group consisting of aluminum, copper, silver and gold as a metal constituting the metal foil or the metal mesh. The metal foil may be an aluminum foil, a copper foil, a silver foil or a gold foil and is preferably an aluminum foil or a copper foil from the viewpoint of obtaining a suitable specific gravity and further excellent electromagnetic wave shielding properties.

The metal mesh may be one in which the above-mentioned metal fibers are woven into a mesh shape, and an organic fiber such as a natural fiber or a synthetic fiber or an inorganic fiber is plated with a conductive metal by sputtering, sputtering, vapor deposition, or the like. What is covered may be a mesh. Examples of the natural fiber include cotton and hemp. Examples of synthetic fibers include polyester fibers, polyolefin fibers, and aramid fibers. Examples of the inorganic fiber include carbon fiber and glass fiber. The conductive metal may be aluminum, copper, silver or gold as described above, and may be nickel or zinc.

The thickness of the conductive layer 7 is preferably 10 μm or more from the viewpoint of further improving the electromagnetic wave shielding property, and preferably 300 μm or less and 200 μm or less from the viewpoint that the flexibility and weight of the heat dissipation sheet 5 are suitable. It may be 100 μm or less, or 50 μm or less.

The heat conductive resin layers 8 and 9 are not particularly limited, but are formed of, for example, a cured product of a heat conductive resin composition containing (A) a resin component and (B) a heat conductive filler.

<(A) Resin component>
The resin component (A) is preferably a silicone resin component (a) containing a silicone resin, from the viewpoint of being able to obtain the heat dissipation sheet 5 which is excellent in flexibility and further excellent in thermal conductivity (heat dissipation).

The silicone resin component (a) is not particularly limited and may be a component that can be cured by a curing reaction such as peroxide crosslinking, condensation reaction crosslinking, addition reaction crosslinking, ultraviolet crosslinking, etc., preferably addition reaction crosslinking It is a component that can be cured by the curing reaction by. The silicone resin component (a) preferably contains an addition reaction type silicone resin, more preferably a one-component addition reaction type or a two-component addition reaction type silicone resin.

The (a) silicone resin component is preferably (a1) at least an organopolysiloxane having a vinyl group at the terminal or side chain (hereinafter, also referred to as "organopolysiloxane having a vinyl group") and (a2) at least an end. Alternatively, a two-liquid addition reaction type liquid silicone resin component containing an organopolysiloxane having two or more H-Si groups in its side chain (hereinafter also referred to as "organopolysiloxane having an H-Si group"). ..

In the silicone resin component (a), (a1) and (a2) react and cure to form a silicone rubber. When such a silicone resin component (a) is used together with the heat conductive filler (B), the heat conductive resin composition may contain the heat conductive filler in a large content of, for example, 40 to 85% by volume. Even if it exists, a highly flexible heat conductive resin layer can be obtained. Further, since a large amount of heat conductive filler can be contained, a heat conductive resin layer having high heat conductivity can be obtained.

(A1) is an organopolysiloxane having a vinyl group at least somewhere in its terminal or side chain, and may have either a linear structure or a branched structure. The organopolysiloxane having a vinyl group is, for example, one in which a part of the R portion is a vinyl group in the structure represented by (Si—R) in the molecule of the organopolysiloxane.

The (a1) organopolysiloxane having a vinyl group specifically has, for example, a structural unit represented by the following formula (a1-1) or a terminal structure represented by the formula (a1-2). You can The organopolysiloxane (a1) having a vinyl group may have, for example, a structural unit represented by the formula (a1-1) and a structural unit represented by the formula (a1-3). It may have a terminal structure represented by 2) and a structural unit represented by the formula (a1-3). However, the organopolysiloxane (a1) having a vinyl group is not limited to those having these structural units or terminal structures.

The content of the vinyl group in (a1) may be 0.01 mol% or more, 15 mol% or less, or 5 mol% or less, preferably 0.01 to 15 mol%, more preferably It is 0.01 to 5 mol %. The “vinyl group content” in the present invention means the ratio (mol %) of the number of moles of vinyl group to the total number of moles of vinyl group and Si atom in (a1).

The vinyl group content is measured by the following method.
The content of vinyl groups is measured by NMR. Specifically, for example, ECP-300NMR manufactured by JEOL Co., Ltd. is used, and the measurement is carried out by dissolving an organopolysiloxane having a vinyl group in deuterated chloroform as a deuterated solvent. Ratio of the number of moles of vinyl group when the total number of moles of vinyl group calculated from the measurement results and the number of moles of Si atom (derived from Si—CH ₃ group _, H—Si group, etc.) is 100 mol %. Is the vinyl group content (mol %).

The (a1) organopolysiloxane having a vinyl group is preferably an alkylpolysiloxane having an alkyl group in addition to the vinyl group. The alkyl group is preferably an alkyl group having 1 to 3 carbon atoms (eg, methyl group, ethyl group, etc.), and more preferably a methyl group. The organopolysiloxane (a1) having a vinyl group may be a methylpolysiloxane having a vinyl group at the terminal and/or side chain.

The mass average molecular weight (also referred to as a weight average molecular weight; hereinafter the same) of the organopolysiloxane (a1) having a vinyl group is preferably less than 400,000 and may be 200,000 or less, or 10,000 or more, or It may be 15,000 or more, more preferably 10,000 to 200,000, and further preferably 15,000 to 200,000. The mass average molecular weight of the organopolysiloxane (a1) having a vinyl group is measured by the method described in Examples.

(A2) is an organopolysiloxane having two or more H-Si groups at least at some of its terminals or side chains, and may have either a linear structure or a branched structure. The organopolysiloxane having an H-Si group is, for example, one in which a part of the R portion is H (hydrogen atom) in the structure represented by (Si-R) in the molecule of the organopolysiloxane. is there.

The (a2) H-Si group-containing organopolysiloxane specifically has, for example, a structural unit represented by the following formula (a2-1) or a terminal structure represented by the formula (a2-2). You can do it. The (a2) H-Si group-containing organopolysiloxane may have, for example, a structural unit represented by the formula (a2-1) and a structural unit represented by the formula (a2-3). It may have a terminal structure represented by a2-2) and a structural unit represented by the formula (a2-3). However, the (a2) H-Si group-containing organopolysiloxane is not limited to those having these structural units or terminal structures.

The content of the H-Si group in (a2) may be 0.01 mol% or more, 15 mol% or less or 5 mol% or less, and preferably 0.01 to 15 mol%. It is preferably 0.01 to 5 mol %. The “content of H—Si group” in the present invention means the ratio (mol %) of the number of moles of H—Si group to the number of moles of Si atom in (a2).

The H-Si group content is measured by the following method.
The H-Si group content is measured by NMR. Specifically, for example, ECP-300NMR manufactured by JEOL is used, and an organopolysiloxane having an H—Si group is dissolved in deuterated chloroform as a deuterated solvent for measurement. The ratio of the number of moles of the H—Si group when the number of moles of the Si atom (derived from the Si—CH ₃ group _{, the} H—Si group, etc.) calculated from the measurement results is 100 mol %, Content (mol %).

The (a2) organopolysiloxane having an H-Si group is preferably an alkylpolysiloxane having an alkyl group in addition to the H-Si group. The alkyl group is preferably an alkyl group having 1 to 3 carbon atoms (eg, methyl group, ethyl group, etc.), and more preferably a methyl group. The (a2) organopolysiloxane having an H-Si group may be a methylpolysiloxane having two or more H-Si groups at the terminal and/or side chain.

The mass average molecular weight of the (a2) organopolysiloxane having an H-Si group is preferably 400,000 or less, 200,000 or less, 10,000 or more or 15,000 or more, It is more preferably 10,000 to 200,000, and even more preferably 15,000 to 200,000. (A2) The mass average molecular weight of the organopolysiloxane having an H-Si group is measured by the method described in Examples.

(A1) Organopolysiloxane having a vinyl group and (a2) Organopolysiloxane having an H-Si group are other structures having other organic groups such as phenyl group and trifluoropropyl group in the side chain of the polysiloxane skeleton. May be further included. The structural unit having another structure may be a structural unit derived from phenylmethylsiloxane or diphenylsiloxane. The organopolysiloxane that constitutes the silicone resin (a) may be a modified organopolysiloxane having a functional group such as an epoxy group.

(A) The viscosity of the silicone resin component at 25° C. may be 100 mPa·s or more or 350 mPa·s or more, 2,500 mPa·s or less, or 2,000 mPa·s or less, for example, 100 to 2 , 500 mPa·s, preferably 100 to 2,000 mPa·s, and more preferably 350 to 2,000 mPa·s. When the viscosity of the (a) silicone resin component at 25° C. is 100 mPa·s or more, it is advantageous in that the thermal conductive resin layer can be prevented from tearing, and (a) the viscosity of the silicone resin component at 25° C. Is 2,500 mPa·s or less, which is advantageous in that it is easy to highly fill the heat conductive filler.

The viscosity of the silicone resin component (a) at 25° C. can be measured by using, for example, a Brookfield type B viscometer “RVDVIT”. The spindle uses an f-shaft and is measured as viscosity at 20 rpm.

The silicone resin component (a) preferably contains a thermosetting organopolysiloxane. The silicone resin component (a) may further contain a curing agent (crosslinkable organopolysiloxane) in addition to the polyorganopolysiloxane (also referred to as a base polymer or a main component). The silicone resin component (a) may further contain an addition reaction catalyst for promoting the addition reaction.

As the silicone resin component (a) as described above, commercially available products can be used. The commercially available silicone resin component is, for example, "TSE-3062" "X14-B8530" manufactured by Momentive Co., Ltd., "SE-1885A/B" manufactured by Toray Dow Corning Co., Ltd. as a two-liquid addition reaction type liquid silicone rubber. Good, but not limited to these specific commercial ranges.

The resin component (A) may further contain other resins such as acrylic resin and epoxy resin in addition to the silicone resin component (a).

The content of the (A) resin component ((a) silicone resin component) may be 10% by volume or more or 15% by volume or more, and 65% by volume or less or 60% by volume based on the total volume of the heat conductive resin layer. It may be not more than volume %, preferably 10 to 65 volume %, and more preferably 15 to 60 volume %. When the content of the (A) resin component ((a) silicone resin component) is 10% by volume or more, flexibility can be increased, and when the content is 65% by volume or less, it is easy to avoid a decrease in thermal conductivity. Is advantageous.

<(B) Thermally conductive filler>
The thermally conductive filler is, for example, a filler having a thermal conductivity of 10 W/m·K or more. The thermally conductive filler may be aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, metallic aluminum, graphite or the like. As the thermally conductive filler, these may be used alone or in combination of two or more. The heat conductive filler preferably has a spherical shape (preferably a sphericity of 0.85 or more).

The heat conductive filler is preferably aluminum oxide because it exhibits higher heat conductivity and has a good filling property with the resin. Aluminum oxide (hereinafter also referred to as “alumina”) can be used in any of flame spraying method of aluminum hydroxide powder, Bayer method, ammonium alum thermal decomposition method, organic aluminum hydrolysis method, aluminum underwater discharge method, freeze drying method, and the like. It may be manufactured by the method. Aluminum oxide is preferably produced by a flame spraying method of aluminum hydroxide powder from the viewpoint of controlling the particle size distribution and controlling the particle shape.

The crystal structure of alumina may be either a single crystal or a polycrystal. The crystal phase of alumina is preferably the α phase from the viewpoint of high thermal conductivity. The specific gravity of alumina is preferably from the viewpoint that the thermal conductivity can be further increased (for example, 2.5 W/m·K or more) while avoiding an increase in the ratio of the voids and low crystalline phases existing inside the alumina particles. Is 3.7 or more.

Alumina is preferably spherical. When the alumina is spherical, the sphericity of the alumina is from the viewpoint of suppressing the fluidity from decreasing and the filler segregating in the heat conductive resin layer, and the accompanying increase in the variation in physical properties. , And preferably 0.85 or more. Alumina having a sphericity of 0.85 or more is available as a commercial product, for example, spherical alumina DAW45S (trade name), spherical alumina DAW05 (trade name), spherical alumina ASFP20 (trade name) manufactured by Denka Corporation. And so on.

In the particle size distribution, the thermally conductive filler preferably has a maximum value (peak) in a particle size range of 10 μm or more and 100 μm or less, 1 μm or more and less than 10 μm, or less than 1 μm. The particle size distribution of the heat conductive filler can be adjusted by classifying and mixing the heat conductive filler.

The thermally conductive filler preferably has a maximum value (peak) in the range of particle size of 10 μm or more and 100 μm or less, and a maximum value (peak) in the range of particle size of 1 μm or more and less than 10 μm. And a heat conductive filler (B-3) having a maximum value (peak) in a particle diameter range of less than 1 μm. The heat conductive filler (B-1) may be a heat conductive filler having an average particle size of 10 μm or more and 100 μm or less. The heat conductive filler (B-2) may be a heat conductive filler having an average particle size of 1 μm or more and less than 10 μm. The heat conductive filler (B-3) may be a heat conductive filler having an average particle size of less than 1 μm. The particle size distribution and average particle size of the heat conductive filler are measured by the methods described in Examples.

The ratio of the thermally conductive filler (B-1) is preferably 15% by volume or more, 20% by volume or more, 30% by volume or more, or 40% by volume or more with respect to the total volume of the thermally conductive filler. It may be 70 vol% or less, 60 vol% or less, or 50 vol% or less, more preferably 20 to 60 vol%.

The ratio of the thermally conductive filler (B-2) may be 10% by volume or more, 12% by volume or more, or 20% by volume or more, and 40% by volume or less, 35% with respect to the total volume of the thermally conductive filler. It may be less than or equal to 30% by volume, preferably 10 to 30% by volume, more preferably 12 to 30% by volume.

The proportion of the thermally conductive filler (B-3) may be 5% by volume or more or 8% by volume or more, and 30% by volume or less, 25% by volume or less, 20% by volume with respect to the total volume of the thermally conductive filler. % Or less or 15% by volume or less, preferably 5 to 30% by volume, more preferably 8 to 20% by volume.

The content of the thermally conductive filler may be 20% by volume or more or 30% by volume or more, preferably 35% by volume or 40% by volume or more, with respect to the entire volume of the thermally conductive resin layer, and 95 It may be less than or equal to 80% by volume, preferably less than or equal to 85% by volume, and more preferably from 40 to 85% by volume. When the content of the heat conductive filler is 35% by volume or more, the heat conductivity of the heat conductive resin layer is further improved. When the content of the thermally conductive filler is 85% by volume or less, deterioration of the fluidity of the thermally conductive resin composition can be easily avoided, and the thermally conductive resin layer can be easily produced.

The heat conductive resin composition further contains a reaction retarder such as acetyl alcohols and maleic acid esters, a thickener such as Aerosil or silicone powder having a particle size of 10 to several hundreds μm, a flame retardant, a pigment and the like. be able to.

The thickness of each of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 may be 0.1 mm or more and may be 10 mm or less. The thermal conductivity of each of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 is preferably 0.5 W/mK or more.

The thickness of the heat dissipation sheet 5 is preferably 0.2 mm or more, 1 mm or more or 1.5 mm or more, 15 mm or less or 12 mm or less, preferably 10 mm or less, 0.2 mm to It may be 10 mm. When the thickness of the heat dissipation sheet 5 is 0.2 mm or more, it is possible to suppress an increase in surface roughness due to the heat conductive filler and a decrease in heat conductivity accompanying it. When the thickness of the heat dissipation sheet 5 is 10 mm or less, a decrease in thermal conductivity can be suppressed. The thickness of the heat dissipation sheet 5 is based on the thickness of the heat conductive resin composition after curing. The heat dissipation sheet 5 has a high thermal conductivity and a thermal conductivity of 0.5 W/mK or more.

The Asker C hardness of the heat dissipation sheet 5 is preferably less than 40, more preferably 35 or less, and further preferably 30 or less. The lower limit of the Asker C hardness is preferably 5 or more from the viewpoint of excellent handleability when handling the heat dissipation sheet 5.

In the heat dissipation sheet 5, for example, the heat conductive resin composition is arranged on one surface of the conductive layer 7 to form one of the first heat conductive resin layer 8 and the second heat conductive resin layer 9. In the step (a-1), the thermally conductive resin composition is arranged on the other surface of the conductive layer 7, and the other of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 is formed. It is manufactured by a manufacturing method including the step (a-2).

In another embodiment of the method for manufacturing the heat dissipation sheet 5, the heat conductive resin composition is arranged on a resin film (for example, PET film), and the first heat conductive resin layer 8 and the second heat conductive resin layer 8 are formed. On the step (b-1) of forming one of the conductive resin layers 9 and the first heat conductive resin layer 8 or the second heat conductive resin layer 9 formed in the step (b-1), A step (b-2) in which the conductive layer 7 is provided (for example, laminating), and a thermally conductive resin composition is disposed on the conductive layer 7 provided in the step (b-2) to obtain a first thermal conductivity. The step (b-3) of forming the other of the resin layer 8 and the second heat conductive resin layer 9 may be included.

The heat conductive resin composition used in the manufacturing method of each embodiment can be obtained by a known method, for example, by mixing the components (A) and (B). A mixer such as a roll mill, a kneader or a Banbury mixer is used for mixing.

In the step (a-1), the step (a-2), the step (b-1) and the step (b-3), the method of disposing the heat conductive resin composition is preferably a doctor blade method. The method may be an extrusion method, a pressing method, a calender roll method, or the like, depending on the viscosity of the heat conductive resin composition.

In the step (a-1), the step (a-2), the step (b-1) and the step (b-3), for example, the first heat conduction is performed by heating and curing the heat conductive resin composition. The conductive resin layer 8 or the second heat conductive resin layer 9 may be formed.

The heat curing is performed using a general hot air dryer, a far infrared dryer, a microwave dryer or the like. The heating temperature is preferably 50 to 200°C. When the heating temperature is 50° C. or higher, crosslinking easily proceeds sufficiently, and when the heating temperature is 200° C. or lower, deterioration due to heating can be suppressed. The heat curing time is preferably 2 to 14 hours.

In another embodiment of the heat dissipation sheet 5, cuts (a plurality of cut lines) are formed on the surfaces of the first heat conductive resin layer 8 and the second heat conductive resin layer 9 (the surface opposite to the conductive layer 7). ) May be formed. FIG. 3 is a perspective view showing a heat dissipation sheet according to another embodiment. As shown in FIG. 3, in this heat dissipation sheet 5B, the first heat conductive resin layer 8B has cuts 10 (plural cut lines) on its surface (the surface opposite to the conductive layer 7). .. Thereby, the heat dissipation sheet 5B has high flexibility and high followability in addition to high thermal conductivity.

In the embodiment shown in FIG. 3, the cut 10 is formed only on one side (the first heat conductive resin layer 8) of the heat conductive resin layer, but in another embodiment, the cut 10 is formed. Notches may be formed in both (the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9).

By the way, in a conventional heat conductive sheet, a groove (a groove having a predetermined width) may be provided in the heat conductive resin layer. However, such a heat conductive sheet is used for an electronic component and a housing. When sandwiched between them, the air that cannot be discharged remains in the groove of the heat conductive resin layer, and the thermal resistance may increase (the thermal conductivity may decrease). On the other hand, when the heat dissipation sheet 5B is sandwiched between the electronic component 4 and the housing 6, the heat conductive resin layers 8 and 9 are provided with the cuts, so that the direction in which the respective layers are laminated in the heat dissipation sheet 5B. The repulsive force (force in the compressing direction) generated in (1) can be released in the direction perpendicular to the stacking direction, and it becomes difficult for air to enter.

In addition, since the heat dissipation sheet 5B has high conformability to the shape of the application target, it is difficult for an excessive load to be applied to the electronic component 4 and the housing 6, and the risk of damage can be reduced. In addition, even when the electronic component 4 and the housing 6 have irregularities, the heat dissipation sheet 5B follows the irregularities and exhibits high adhesion. As described above, since the heat dissipation sheet 5B has excellent adhesion, it can more efficiently dissipate the heat generated in the electronic component 4, and thus also exhibits better heat dissipation.

From the above, the heat dissipation sheet 5B is particularly suitable for applications in which a load is sandwiched between the electronic component 4 and the housing 6. Therefore, the heat dissipation sheet 5B is preferably a non-adhesive sheet having no adhesiveness (a non-adhesive sheet including the non-adhesive thermally conductive resin layers 8 and 9).

From the viewpoint of suitably obtaining the effect of the notch 10 as described above, the notch 10 is composed of one or more linear notches (hereinafter referred to as “notch lines”). This cut line has, for example, a width such that a streak of a trace of cutting can be seen. The width of the score line (the length in the widthwise direction) makes it difficult for air to enter the heat dissipation sheet 5B, which can further improve the thermal conductivity (further reduce the thermal resistance), and the flexibility and the heat dissipation sheet 5B. From the viewpoint that the followability can be further improved, the smaller is preferable, preferably 300 μm or less, more preferably less than 300 μm, further preferably 100 μm or less, particularly preferably 50 μm or less. The width (length in the widthwise direction) of the score line may be 2 μm or more, preferably 2 μm or more and less than 300 μm, and more preferably 2 μm or more and 50 μm or less.

The score line may be, for example, a straight line shape, or a curved shape such as a meandering shape and a wavy shape. The wave shape may be, for example, a sine wave shape, a sawtooth wave shape, a rectangular wave shape, a trapezoidal wave shape, a triangular wave shape, or the like.

The planar shape of the cut 10 is not particularly limited. In the embodiment shown in FIG. 3, the planar shape of the notch 10 is a lattice shape. That is, the cuts 10 shown in FIG. 3 are configured by arranging a plurality of linear cut lines in a grid shape in a plan view. The planar shape of each quadrangle forming the lattice may be, for example, a rectangular shape or a square shape.

In another embodiment, the planar shape of the notch may be linear, broken (perforated), polygonal, elliptical, circular, or the like.

The broken line shape (perforated shape) is, for example, a plurality of linear cut lines arranged at a predetermined interval in one direction (extending direction of the cut line) (a portion with a cut line and a portion without a cut line). Is repeated alternately).

The polygonal shape is not particularly limited, and examples thereof include a triangular shape, a quadrangular shape, a pentagonal shape, a hexagonal shape, and a star shape. Examples of the quadrilateral shape include a trapezoidal shape, a rhombus shape, and a parallelogram shape.

The planar shape of the notch 10 is preferably linear, corrugated, diamond-shaped, circular, star-shaped and grid-shaped, more preferably linear, diamond-shaped and grid-shaped, and further preferably cut-processed. From the viewpoint of workability and high followability at the time, it is a lattice shape (particularly, a lattice shape in which the planar shape of each quadrangle forming the lattice is a square shape).

The vertical cross-sectional shape of the notch 10 (the shape as viewed from the direction perpendicular to the stacking direction of the layers forming the heat dissipation sheet 5B) is not particularly limited, but may be, for example, a V-shape, a Y-shape, an l-shape (lowercase English letters). It may have an ell shape (straight line shape), an oblique (slash) shape, or the like, and is preferably an l-shape from the viewpoint that it is easy to form the notch 10 even in a state where the layers forming the heat dissipation sheet 5B are stacked. (English small letter L) (straight line).

The notch 10 is preferably not penetrated (it is not penetrated in the heat conductive resin layers 8 and 9 in the thickness direction (stacking direction)). The length of the non-penetrating portion (the length in the thickness direction (stacking direction) of the portions where the cuts are not formed in the heat conductive resin layers 8 and 9) is 0.1 mm or more, 0.15 mm or more, 0. 2 mm or more, or 0.25 mm or more, 6.0 mm or less, 5.0 mm or less, 4.0 mm or less, or 3.0 mm or less, preferably 0.1 mm to 6.0 mm, more preferably. Is 0.15 mm to 5.0 mm, more preferably 0.2 mm to 4.0 mm, and particularly preferably 0.25 mm to 3.0 mm.

The ratio of the depth of the cut 10 (the length of the cut 10 in the thickness direction (the stacking direction) of the heat conductive resin layers 8 and 9) to the thickness of the heat conductive resin layers 8 and 9 is preferably 2%. 10% or more, 20% or more, 30% or more, or 40% or more, preferably 90% or less, 80% or less, or 70% or less, preferably 2% to 90%, more preferably It may be 30% to 80%, more preferably 40% to 70%. When the ratio is within the above range, high flexibility and high followability are easily obtained (for example, the compressive stress (at a compressibility of 20%) can be reduced by 5% or more compared to the case where no cut is provided). , The thermal resistance can be further reduced (the thermal conductivity can be further improved).

The incision 10 can be formed, for example, by using a cutting means, and by moving the cutting means in one of the thickness direction (laminating direction) and the direction perpendicular thereto or in combination thereof. The cutting means can be moved in any direction (shape) such as “oblique direction” or “wavy”.

The cutting means may be, for example, a cutting blade, a laser, a water jet (water cutter), or the like, and is preferably a cutting blade because the cutting line is easily narrowed and processing is easy. The method of forming the notch 10 may be slit processing with a cutting blade, processing with a laser knife, or the like.

When making a cut in the heat dissipation sheet 5, it is preferable to make a cut so that the difference in Asker C hardness before and after cutting is preferably 2 or more, more preferably 5 or more. When the difference in Asker C hardness before and after cutting is 2 or more, the effect of improving flexibility is easily obtained, and the followability becomes better. This "difference in Asker C before and after cutting" can be calculated by "(Asker C hardness before cutting)-(Asker C hardness after cutting)".

When the electromagnetic wave shielding heat dissipation sheet has a cut, it is preferable that the heat conductive resin layer in which the cut is formed is brought into contact with the electronic component 4. In other words, when the cut 10 is formed in either one of the first thermally conductive resin layer 8 that contacts the electronic component 4 and the second thermally conductive resin layer 9 that contacts the housing 6, as shown in FIG. It is preferable to form the notch 10 in the first heat conductive resin layer 8 that contacts the electronic component 4, as in the electromagnetic wave radiation sheet 5B shown in FIG.

In this case, the heat dissipation sheet 5B can follow the shape of the contact surface of the electronic component 4 with the first heat conductive resin layer 8 due to the high followability, and stress is applied to the heat dissipation sheet 5B due to the high flexibility. Even so, since the stress can be relaxed, it is difficult to damage the electronic component 4. Since the heat dissipation sheet 5B has high flexibility and high followability as well as high heat conductivity, the heat generated from the electronic component 4 can be transmitted to the housing 6 particularly efficiently. Therefore, in the electronic device 1, the heat from the electronic component 4 can be efficiently released to the outside of the electronic device 1.

In the electronic device 1 described above, since the electromagnetic wave shielding heat dissipation sheet 5 has the electromagnetic wave shielding property, the electromagnetic wave generated from the electronic component 4 can be confined and the electromagnetic wave from the outside can be blocked. In addition, since the electromagnetic wave shielding heat dissipation sheet 5 also has an insulating property, the spatial distance between the electronic component 4 and the housing 6 may be small, and the electronic device 1 can be downsized. Further, when the case 6 is a metal case, the electromagnetic wave shielding property can be further enhanced, but since the electromagnetic wave shielding heat dissipation sheet 5 can shield the electromagnetic wave, it is not necessary to use the metal case. Instead, by using a radiation fin or the like instead to secure heat radiation, it is possible to contribute to further size reduction.

On the other hand, it is difficult to downsize the conventional electronic device as described above. FIG. 4 is a schematic cross-sectional view showing a conventional electronic device. As shown in FIG. 4, in the conventional electronic device 11, the electromagnetic wave shielding heat dissipation sheet is not provided, and the housing 16 blocks the electromagnetic wave generated from the electronic component 4 and heat generated from the electronic component 4. Are emitted to the outside of the electronic device 11. In this case, the housing 16 is made of metal from the viewpoint of obtaining electromagnetic wave shielding properties and heat dissipation properties. However, in order to ensure insulation between the electronic component 4 and the housing 16, the electronic component 4 and the housing 16 are secured. The spatial distance between and is required. Therefore, it is difficult to reduce the size of the conventional electronic device 11.

From the above, the electronic device 1 including the electromagnetic wave shielding heat dissipation sheet 5 of the present embodiment can suppress malfunction and noise due to electromagnetic waves. Further, it is possible to provide the electronic component 4 that can reduce the life of the electronic component 4, the malfunction, and the failure due to the temperature rise, the distortion of the housing, and the like.

Further, according to one embodiment, the electromagnetic wave shielding heat dissipation sheet 5B having both electromagnetic wave shielding property and thermal conductivity, reducing the compressive load (stress), and having high followability to the application target of the electronic component 4 or the like. Can be provided. Further, in the heat dissipation sheet 5B, not the so-called groove but the notch 10 is provided, so that air does not remain, the followability to the application target of the electronic component 4 and the like is high, and the adhesion is also high. Is also high. The heat dissipation sheet 5B is particularly suitable as an electromagnetic wave shielding material for electronic parts and a heat dissipation member.

Furthermore, the heat dissipation sheet 5B is preferably used as a heat dissipation member for electronic parts, which requires close contact between the heat generation surface of the semiconductor element and the heat dissipation surface such as the heat dissipation fins. The heat dissipation sheet 5B is preferably used as an electromagnetic wave shielding material such as an industrial member and a heat conduction member, and is particularly suitable as a high heat conductivity sheet and a heat dissipation member having high flexibility capable of reducing compressive stress at the time of mounting. Is used.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. The present invention is not limited to the examples below.

A resin component (A), which is a two-part addition reaction type silicone containing (a1) an organopolysiloxane having a vinyl group and (a2) an organopolysiloxane having an H-Si group, and (B) a heat conduction agent shown below. The heat-conductive resin composition was prepared by mixing the organic filler with the compounding ratio (volume %) shown in Tables 1 to 3. The total amount of the component (A) and the component (B) was 100% by volume.

[(A) Resin component]
<A-1>
Two-component addition reaction type silicone (organopolysiloxane having vinyl group (vinyl group content 0.3 mol%): organopolysiloxane having H-Si group (H-Si content 0.5 mol%)=1: 1 (mass ratio); SE-1885 manufactured by Toray Dow Corning Co., Ltd.; viscosity at 25° C. 430 mPa·s; mass average molecular weight of each organopolysiloxane: 120,000.
<A-2>
Two-component addition reaction type silicone (organopolysiloxane having vinyl group (vinyl group content 0.8 mol %): organopolysiloxane having H-Si group (H-Si content 1.0 mol %)=1: 1 (mass ratio); TSE-3062 manufactured by Momentive Co.; viscosity at 25° C. 1000 mPa·s; mass average molecular weight of each organopolysiloxane: 25,000)
<A-3>
Two-component addition reaction type silicone (organopolysiloxane having vinyl group (vinyl group content 0.8 mol %): organopolysiloxane having H-Si group (H-Si content 1.0 mol %)=1: 1 (mass ratio); X14-B8530 manufactured by Momentive Co.; viscosity at 25° C. 350 mPa·s; mass average molecular weight of each organopolysiloxane: 21,000)

The mass average molecular weight of the polyorganosiloxane was a value in terms of polystyrene determined from the results of gel permeation chromatography analysis. Separation was performed using a non-aqueous porous gel (polystyrene-dimethylbenzene copolymer), toluene was used as a mobile phase, and a differential refractometer (RI) was used for detection.

[(B) Thermally conductive filler]
The following aluminum oxide (alumina) was used as the heat conductive filler. The “filler total” (volume %) of the thermally conductive fillers in Tables 1 to 3 is the total amount of each spherical filler and each crystalline alumina used.
<B-1>
Spherical alumina (Average particle size: 45 μm, spherical alumina DAW45S manufactured by DENKA CORPORATION)
<B-2>
Spherical alumina (Average particle size: 5 μm, spherical alumina DAW05 manufactured by DENKA CORPORATION)
<B-3>
Crystalline alumina (average particle size: 0.5 μm, manufactured by Sumitomo Chemical Co., Ltd., crystalline alumina AA-05)

The average particle size of the heat conductive filler was measured using "laser diffraction particle size distribution analyzer SALD-20" manufactured by Shimadzu Corporation. As an evaluation sample, 5 g of 50 cc of pure water and 5 g of thermally conductive filler powder to be measured were added to a glass beaker, stirred with a spatula, and then subjected to dispersion treatment for 10 minutes by an ultrasonic cleaner. The solution of the thermally conductive filler powder subjected to the dispersion treatment was added drop by drop to the sampler part of the device using a dropper, and measurement was performed when the absorbance was stable. The laser diffraction type particle size distribution measuring device calculates the particle size distribution from the data of the light intensity distribution of the diffracted/scattered light by the particles detected by the sensor. The average particle diameter is obtained by multiplying the value of the measured particle diameter by the relative particle amount (difference%) and dividing by the total of the relative particle amounts (100%). The average particle diameter is the average diameter of the particles, and can be calculated as the cumulative weight average value D50 (or median diameter) that is the maximum value or the peak value. D50 is the particle size with the highest appearance rate.

Then, using a doctor blade (method), the obtained thermally conductive resin composition was applied to one surface of each conductive layer shown in Tables 1 and 2 to conduct heat conduction with the thickness shown in Tables 1 and 2. After arranging so that the functional resin layer can be obtained, heat curing was performed at 110° C. for 8 hours. Then, after disposing the heat conductive resin composition on the other surface of the conductive layer in the same manner as above, heat curing was performed at 110° C. for 8 hours. Thereby, the heat dissipation sheets of Examples 1 to 9 and Comparative Example 1 were produced.

Further, in Examples 10 to 14, notches were formed in one or both of the heat conductive resin layers in the heat dissipation sheet obtained in Example 8. More specifically, using a cutting blade, linear cut lines were formed in one or both of the heat conductive resin layers in two directions perpendicular to each other to form a grid cut. The width of the score line (length in the lateral direction) is 50 μm or less, the planar shape of each quadrangle forming the grid is a square shape of 1.5 mm×1.5 mm, and the number of quadrangles forming the grid is 15 mm. It was 100 pieces per ² . Further, the depth of cut (length in the thickness direction) and the ratio of the depth to the thickness of the heat conductive resin layer were as shown in Table 3.

Each of the obtained heat dissipation sheets was evaluated by the following method. The results are shown in Tables 1-3.

<Electromagnetic wave shielding properties>
The electromagnetic wave shielding effect at 1 MHz was measured by the KEC method using a heat dissipation sheet of 130×130 mm. It can be said that if the shield effect is 10 dB or more, the electromagnetic wave shielding property is excellent, and if it is 20 dB or more, it is particularly excellent.

<Thermal conductivity>
A sample obtained by cutting a heat dissipation sheet into a TO-3 type was sandwiched between a TO-3 type copper heater case (effective area 6.0 cm ² ) containing a transistor and a copper plate, and 10% of the initial thickness was compressed. With the load applied as described above, a power of 15 W was applied to the transistor and it was held for 5 minutes. Then, the temperature (° C.) of each of the heater case side and the copper plate side was measured. From the measurement results, the following formula:
Thermal resistance (°C/W) = (heater case side temperature (°C)-copper plate side temperature (°C)) / power (W)
The thermal resistance was calculated by Then, using the above thermal resistance, the following formula:
Thermal conductivity (W/m·K)=thickness of sample (m)/(cross-sectional area (m ² )×thermal resistance (° C./W))
The thermal conductivity was calculated by It can be said that if the thermal conductivity is 0.5 W/m·K or more, the thermal conductivity is excellent, and if it is 2 W/m·K or more, it is more excellent, and if it is 4 W/m·K or more, it is particularly excellent. Can be said.

<Asker C hardness>
The Asker C hardness was measured by "Asker rubber hardness meter C type" manufactured by Kobunshi Keiki Co., Ltd. It can be said that if the Asker C hardness is less than 40, the heat dissipation sheet has high flexibility, and if the Asker C hardness is 15 or less, the heat dissipation sheet has particularly high flexibility.

For Examples 10 to 14, the following compressive stress was also evaluated. The results are shown in Table 3.
<Compressive stress>
After punching out the heat dissipation sheet into 60×60 mm, the load (N) at a compression rate of 20% was measured against the thickness with a tabletop tester (EZ-LX manufactured by Shimadzu Corporation), and the compression stress (N ).
Also, the following formula:
Compressive stress reduction rate (%) = {amount of change in thickness due to compression (mm) x 100}/thickness before compression (mm)
At, the compressive stress reduction rate was calculated. It can be said that the compression stress can be suitably reduced if the reduction rate of the compression stress is 5% or more.

Regarding Examples 1 to 4, it was possible to obtain a heat dissipation sheet having a high electromagnetic wave shielding property depending on the type and thickness of the conductive layer. Further, regarding Examples 5 to 9, it was possible to obtain a heat dissipation sheet having a high electromagnetic wave shielding property regardless of the molecular weight of the silicone resins of the components (A) and (B) and the amount of the heat conductive filler. On the other hand, in Comparative Example 1, although heat dissipation and flexibility could be imparted, electromagnetic shielding properties could not be obtained due to the use of insulating PET.

Regarding Examples 10 to 14, by forming the notches, it was possible to obtain a heat dissipation sheet having an electromagnetic wave shielding property in which the compressive stress was reduced (the compressive stress of the heat dissipation sheet of Example 8 in which the notches were not formed). Was 226N). Further, it was possible to obtain a flexible heat dissipation sheet having a compression stress reduction rate of 5% or more, even if a cut is formed in one or both of the heat conductive resin layers.

INDUSTRIAL APPLICABILITY The electromagnetic wave shielding heat dissipation sheet of the present invention has both high electromagnetic wave shielding property and thermal conductivity, reduces the compressive load (compressive stress) when the sheet is used, and has high followability to the application target. INDUSTRIAL APPLICABILITY The electromagnetic wave shielding heat dissipation sheet of the present invention can be suitably applied to an electromagnetic wave shield and a heat dissipation member of electronic parts. In particular, it is possible to provide an electromagnetic wave shielding heat radiation sheet suitable for electric components of a car (car navigation, radio, automatic driving related devices, etc.).

DESCRIPTION OF SYMBOLS 1... Electronic device, 2... Board, 3... Solder, 4... Electronic component, 5... Electromagnetic wave shielding heat dissipation sheet, 6... Housing, 7... Conductive layer, 8... First heat conductive resin layer, 9... 2 thermally conductive resin layers, 10... Notches.

Claims (12)

Electronic components,
Electromagnetic wave shielding heat dissipation sheet,
A housing that accommodates the electronic component and the electromagnetic wave shielding heat dissipation sheet,
The electromagnetic wave shielding heat dissipation sheet includes a first heat conductive resin layer, a conductive layer, and a second heat conductive resin layer in this order, and the first heat conductive resin layer is the electron An electronic device, which is arranged so as to come into contact with a component and the second heat conductive resin layer to come into contact with the housing. The electronic device according to claim 1, wherein the conductive layer is formed of a metal foil or a metal mesh. The electronic device according to claim 1, wherein the conductive layer contains at least one selected from the group consisting of aluminum, copper, silver, and gold. The electronic device according to claim 1, wherein the first thermally conductive resin layer and the second thermally conductive resin layer each include a silicone resin and a thermally conductive filler. The electronic device according to claim 4, wherein the content of the thermally conductive filler is 40 to 85% by volume with respect to each of the first thermally conductive resin layer and the second thermally conductive resin layer. .. The electronic device according to claim 1, wherein a plurality of cuts are formed in at least one of the first thermally conductive resin layer and the second thermally conductive resin layer. An electromagnetic wave shielding heat dissipation sheet comprising a first heat conductive resin layer, a conductive layer, and a second heat conductive resin layer in this order. The electromagnetic wave shielding heat dissipation sheet according to claim 7, wherein the conductive layer is formed of a metal foil or a metal mesh. The electromagnetic wave shielding heat dissipation sheet according to claim 7 or 8, wherein the conductive layer contains at least one selected from the group consisting of aluminum, copper, silver and gold. The electromagnetic wave shielding heat dissipation according to any one of claims 7 to 9, wherein the first thermally conductive resin layer and the second thermally conductive resin layer each contain a silicone resin and a thermally conductive filler. Sheet. The electromagnetic wave shield according to claim 10, wherein the content of the thermally conductive filler is 40 to 85% by volume with respect to each of the first thermally conductive resin layer and the second thermally conductive resin layer. Heat dissipation sheet. The electromagnetic wave shielding heat dissipation sheet according to any one of claims 7 to 11, wherein a plurality of cuts are formed in at least one of the first thermally conductive resin layer and the second thermally conductive resin layer. ..

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