KR20180059185A - Insulating and heat dissipative sheet and manufacturing method thereof - Google Patents

Abstract

An embodiment of the present invention relates to an electrically insulating and heat dissipative sheet and a manufacturing method thereof. The electrically insulating and heat dissipative sheet includes a thermally conductive layer and a thermally conductive electrically insulating layer which is formed on at least one surface of the thermally conductive layer and includes a resin and thermally conductive anisotropic particles dispersed in the resin. The thermally conductive anisotropic particles of the thermally conductive electrically insulating layer have the percentage of the integral intensity of the diffraction peak of a plane (100) which is 10% or more, with regard to the sum of the integral intensity of the diffraction peak of a plane (002) and the integral intensity of the diffraction peak of the plane (100) at X-ray diffraction analysis. It is possible to reduce thermal conductivity in a vertical direction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrically insulating heat-

The present invention relates to an electrically insulating heat-radiating sheet and a method of manufacturing the same.

2. Description of the Related Art In recent years, wirings in electronic devices or semiconductor devices have become higher in density, more electronic components have been mounted, and semiconductor devices have become highly integrated, thereby increasing the amount of heat generated per unit area in electronic devices and semiconductor devices. Therefore, there is a need for a method capable of efficiently emitting heat in an electronic device or a semiconductor device.

As an example, graphite is a material having thermal conductivity, and it is attempted to use the graphite sheet as a heat radiating material for emitting heat in an electronic device or a semiconductor device.

The conventional graphite sheet shows a thermal conductivity of about 1500 W / mK in the horizontal direction and a thermal conductivity of about 3 W / mK in the vertical direction. However, graphite has a disadvantage of not having electrical insulation.

In order to overcome such disadvantages, attempts have been made to perform an insulating coating on a graphite sheet, but the conventional insulating coating has a disadvantage in that the thermal conductivity in the vertical direction is particularly reduced.

The embodiments described herein are intended to provide an electrically insulating heat sink sheet and a method of manufacturing the same that minimize or increase the decrease in thermal conductivity in the vertical direction.

One embodiment of the present invention is

Heat conduction layer and

And a thermally conductive electrically insulating layer provided on at least one surface of the thermally conductive layer and including a resin and thermally conductive anisotropic particles dispersed in the resin,

The thermally conductive anisotropic particles of the thermally conductive anisotropic layer have a diffraction peak of (100) plane relative to the sum of the integral intensity of the diffraction peak of the (002) plane and the integrated intensity of the diffraction peak of the (100) Wherein the percentage of the integral strength of the electrically insulating sheet is 10% or more.

According to another embodiment of the present invention, the percentage is at least 30%, preferably at least 50%, more preferably at least 70%.

Another embodiment of the present invention is

Preparing a composition comprising a resin or a precursor of the resin and thermally conductive anisotropic particles;

Applying the composition to at least one surface of the thermally conductive layer or preparing a sheet using the composition and attaching the sheet to at least one surface of the thermally conductive layer to form an electrically insulating layer on at least one surface of the thermally conductive layer; And

Forming a thermally conductive electrically insulating layer by aligning the maximum diameter direction of at least a part of the thermally conductive anisotropic particles parallel to the thickness direction of the electrically insulating layer by applying an electric field during or after the production of the electrically insulating layer

The heat-radiating sheet having a heat-radiating property.

The embodiments described herein include thermally conductive anisotropic particles in an electrically insulating layer provided on at least one side of a thermally conductive layer and at least a part of the particles have their maximum diameters aligned in parallel with the layer thickness direction, The thermal conductivity in the vertical direction of the heat-radiating sheet may not be significantly reduced or increased compared with the thermal conductivity of the heat conduction layer. The heat-radiating sheet having the above-described structure is excellent in adhesion between the heat conduction layer and the thermally conductive electric insulation layer, and has flexibility higher than a certain level, so that it can be applied to various electronic devices or semiconductor devices.

1 illustrates a laminated structure of an electrically insulating radiation sheet according to an embodiment of the present application.
2 is a schematic diagram showing the alignment of anisotropic particles under an electric field.
3 is a schematic view of an electric field applying means for manufacturing a thermally conductive electric insulating layer among the electric insulating heat radiation sheets according to one embodiment of the present application.
FIG. 4 is a graph showing the results of X-ray diffraction analysis of the thermally conductive electric insulating layer prepared in Example 1 and the electric insulating layer prepared in Comparative Example 1. FIG.

An electrically insulating heat-radiating sheet according to an embodiment of the present invention includes a thermally conductive layer and a thermally conductive electrically insulating layer provided on at least one surface of the thermally conductive layer. Here, the thermally conductive electrically insulating layer includes a resin and thermally conductive anisotropic particles dispersed in the resin, and the thermally conductive anisotropic particle has an integrated intensity of a diffraction peak of the (002) plane in X-ray diffraction analysis, And the integral intensity of the diffraction peak of the (100) face relative to the sum of the integral intensities of the diffraction peaks of the (100) face is 10% or more. For example, when the thermally conductive anisotropic particle is boron nitride, the diffraction peak of the (002) plane in the X-ray diffraction analysis is a peak at 2? 26.8 degrees and the diffraction peak of the (100) plane in the X- Is a peak at 41.6 degrees.

According to another embodiment of the present invention, the percentage is at least 30%, preferably at least 50%, more preferably at least 70%, and most preferably at least 90%.

The present inventors have found that when the percentage of the integral intensity of the diffraction peak of the (100) face to the sum of the integral intensity of the diffraction peak of the (002) plane and the integral intensity of the diffraction peak of the (100) , The fact that the maximum diameter direction of at least a part of the thermally conductive anisotropic particles is aligned parallel to the thickness direction of the electric insulating layer. Further, when the thermally conductive anisotropic particles are aligned in the electric insulation layer as described above, it has been found that the thermal conductivity in the vertical direction of the heat-radiating sheet can not be significantly reduced or increased compared to the thermal conductivity of the heat-conducting layer. The present invention has been accomplished on the basis thereof, and according to the above-described embodiment, it is possible to provide a heat radiation sheet having electrical insulation and excellent thermal conductivity in the vertical direction.

The larger the percentage of the thermally conductive anisotropic particles whose maximum diameter direction is aligned parallel to the thickness direction of the electrical insulating layer, the greater the percentage of the thermal conductivity of the heat-radiating sheet in the vertical direction.

Fig. 1 illustrates a laminated structure of an electrically insulating radiation sheet according to an embodiment of the present application. Although FIG. 1 shows an example in which a thermally conductive electrically insulating layer is provided on only one side of the thermally conductive layer, a thermally conductive electrically insulating layer may be provided on both sides of the thermally conductive layer, if necessary.

As the thermally conductive layer, those containing a thermally conductive material may be used, and those known as a heat-radiating layer in particular in the field of electronic devices or semiconductor devices may be used. For example, a graphite sheet can be used as the heat conduction layer. The graphite sheet may be a sheet containing artificial graphite or natural graphite, and the composition or thickness thereof may be determined by a person skilled in the art on the basis of the thermal conductivity required for the application to which the heat-radiating sheet is ultimately to be applied. For example, the thickness of the thermally conductive layer is preferably 1 占 퐉 to 1,000 占 퐉.

The thermally conductive anisotropic particles mean thermally conductive particles that are not spherical, that is, particles whose diameters are not all the same. According to one embodiment, it is preferable that the aspect ratio, which is the ratio of the maximum diameter to the minimum diameter of the particles, is 2 or more, preferably 5 or more. The particles may be scaly, round, square, or rod-shaped. According to a preferred embodiment, the thermally conductive anisotropic particles are plate-shaped. In this case, the thickness may be 2-110 nm and the diameter may be 3-50 μm.

The thermal conductivity of the thermally conductive anisotropic particles can be, for example, 100-500 W / mK in in-plane and 5-20 W / mK in the through plane. According to one example, the thermal conductivity of the planar particles of boron nitride is 200-300 W / mK in in-plane and 10 W / mK in the through plane.

According to one embodiment, the thermally conductive anisotropic particles may be a boron nitride (BN) particle, a plate-like alumina, a SiC whisker, or the like. However, boron nitride (BN) having a high in-plane thermal conductivity is preferable.

According to another embodiment of the present invention, the maximum diameter of the thermally conductive anisotropic particles may be 1 μm to 200 μm, 5 μm to 100 μm, and preferably 10 μm to 100 μm.

According to another embodiment, the thermally conductive anisotropic particles may include two or more kinds of particles having different maximum diameters. According to one example, it is preferable that at least one kind of particle is a particle having a maximum particle diameter of 20 m or more. According to one example, the particles having a maximum particle diameter of 20 m or more are preferably 30% by weight or more of the thermally conductive anisotropic particles. In terms of thermal conductivity, the larger the size of the particle, the more the glass. However, when the particle size is too large in the process such as coating, the surface properties of the coating can be impaired. When the particles are too small, the viscosity of the filler increases. For example, it is recommended to use particles with a maximum particle size of 20-100 μm and particles with a maximum diameter of 5-15 μm.

According to another embodiment, the thermally conductive anisotropic particles preferably have a volume resistivity of 10 ¹⁴ ? Cm or more for electrical insulation.

The resin in the thermally conductive electrically insulating layer can be used as a matrix in the layer. For example, a (meth) acrylic resin, a silicone resin, an epoxy resin, a urethane resin, or the like can be used.

According to one embodiment, the resin may be a light or thermally polymerizable monomer or a cured oligomer. As an example, the resin may be a cured product of a polymerizable component comprising a (meth) acrylic monomer or a partial polymer thereof. If necessary, the cured product may further comprise an initiator for curing the polymerizable component, for example, a thermal initiator or a photoinitiator. For example, when boron nitride is used as the thermally conductive anisotropic particles, it is preferable to use a thermal initiator since boron nitride may absorb the photoinitiator depending on the content thereof. In addition, if necessary, the cured product may further comprise a light absorbing agent which absorbs at least a part of the wavelength band of light outside the wavelength for light curing of the polymerizable component.

The polymerizable component may serve as a binder for forming the electric insulation layer.

As the (meth) acrylic monomers, (meth) acrylic monomers having an alkyl group having 1 to 20 carbon atoms can be suitably used. Suitable examples of the (meth) acrylic monomers include ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and the like.

Further, in order to increase the cohesive strength of the composition containing the polymerizable component, the polymerizable component may be copolymerized with a (meth) acrylic monomer having a glass transition temperature (Tg) of 20 占 폚 or higher of a homopolymer (homopolymer) and / (Meth) acrylate. Examples of (meth) acrylic monomers having a Tg of 20 占 폚 or more of the homopolymer include acrylic acid and its anhydride, methacrylic acid and anhydride thereof, itaconic acid and anhydride thereof, maleic acid and anhydride thereof, other carboxylic acid and corresponding anhydride thereof, Acrylamide, substituted acrylamides such as N, N-dimethylacrylamide, nitrogen-containing compounds such as N-vinylpyrrolidone, N vinylcaprolactam , N-vinylpiperidine and acrylonitrile, tricyclodecyl (meth) acrylate, isobornyl (meth) acrylate, hydroxy (meth) acrylate, vinyl chloride and the like. Examples of multifunctional (meth) acrylates include trimethylolpropane (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,6- Di (meth) acrylate, and the like.

According to one embodiment, at least 98% by weight, based on the total amount of the polymerizable component, is an alkyl (meth) acrylic monomer having a glass transition temperature of less than -40 占 폚 of the homopolymer. The flexibility of the heat- desirable. Preferable examples of the alkyl (meth) acrylic monomers include n-butyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate.

The polymerizable component may be a partial polymer of a (meth) acrylic monomer. The partial polymer of the (meth) acrylic monomer means that a part of the (meth) acrylic monomer is preliminarily polymerized. In this case, the viscosity increases and precipitation of the thermally conductive anisotropic particles can be prevented. The partial polymerization of the (meth) acrylic monomer can be carried out by methods such as thermal polymerization, UV polymerization and electron beam polymerization.

The (meth) acrylic monomer or the partial polymer thereof to be used may be used singly or in any combination of two or more kinds. In the present invention, such polymeric components may each be used in various amounts.

The polymerizable component may be included in an amount of 20 to 50 parts by weight based on 100 parts by weight of the thermally conductive electrically insulating layer.

If desired, the resin may further comprise a urethane oligomer. The urethane oligomer preferably contains two or more (meth) acrylate functional groups. The urethane oligomer may be included, for example, in an amount of 1 to 5 parts by weight based on 100 parts by weight of the thermally conductive electrically insulating layer. Such a urethane oligomer can act as a crosslinking agent component and can perform a crosslinking function while providing flexibility to the electric insulation layer due to the nature of the oligomer. The oligomer preferably has a weight average molecular weight of 1,000 to 50,000. According to one example, the urethane oligomer may be contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the resin.

As the initiator, those known in the art may be used. For example, 0.05 to 2 parts by weight may be used relative to 100 parts by weight of the polymerizable component.

The light absorbing agent may be one capable of absorbing light of at least a part of the wavelength of less than 350 nm, for example, 0.5 to 10 parts by weight based on 100 parts by weight of the polymerizable component.

Further additives may be used according to need, and for example, a thermal polymerization initiator, a plasticizer, an antioxidant, a flame retardant, a tackifier, a precipitation inhibitor, a surfactant, a defoamer, a colorant and an antistatic agent may be used.

According to an embodiment of the present invention, the content of the thermally conductive anisotropic particles in the thermally conductive electrically insulating layer is preferably 30 wt% to 70 wt%.

Such a content range is advantageous for imparting the flexibility of the heat-radiating sheet at the same time as the thermal conductivity of the heat-radiating sheet in the vertical direction is not greatly reduced or increased as compared with that of the heat-conducting layer. If the content of the particles is too large, the thermal conductivity may be reduced because the maximum diameter direction of the particles is prevented from being aligned parallel to the thickness direction of the electric insulating layer.

According to one embodiment, the thermally conductive electrically insulating layer may have a layer thickness of 1 μm to 1,500 μm and preferably 1 μm to 1,000 μm.

According to another embodiment, the thermal conductivity of the thermally conductive electrical insulating layer is preferably 2 W / mK or more, and the volume resistivity is preferably 10 ⁹ Ωcm or more. The higher the thermal conductivity, the better.

Another embodiment of the present invention relates to a method of manufacturing an electrically insulating heat radiation sheet,

Preparing a composition comprising a resin or a resin precursor, and thermally conductive anisotropic particles;

Applying the composition to at least one surface of the thermally conductive layer or preparing a sheet using the composition and attaching the sheet to at least one surface of the thermally conductive layer to form an electrically insulating layer on at least one surface of the thermally conductive layer; And

And applying an electric field to the electric insulating layer to align the thermally conductive anisotropic particles in the thickness direction of the electric insulating layer to form a heat conductive electric insulating layer.

First, the resin or resin precursor may be a polymerizable component composed of a (meth) acrylic monomer or a partial polymer thereof. The polymerizable component is as described above.

According to one embodiment, when the (meth) acrylic monomer or the partial polymer thereof is used as the resin or the resin precursor, it is advantageous to disperse the thermally conductive anisotropic particles in the resin as compared with the case of using a material consisting solely of a polymer, So that the thermally conductive anisotropic particles can be easily aligned in a specific direction.

The resin or resin precursor may comprise a urethane oligomer as described above.

The resin or the resin precursor, and the composition comprising the thermally conductive anisotropic particles may further include an initiator, a light absorber or other additives such as a thermal initiator or a photoinitiator, as described above, as described above.

The composition may further comprise a solvent if necessary. For example, when a thin film having a thickness of 500 μm or less is required, a solvent may be additionally used to control the viscosity of the composition. As the solvent, a solvent such as methyl ethyl ketone, hexane, or toluene may be used alone or in combination.

When the electrical insulation layer is formed using the above composition, not only the process is easy, but also it is easy to uniformly disperse the thermally conductive anisotropic particles.

The step of forming the electrically insulating layer may be performed by applying the composition to at least one surface of the thermally conductive layer, or by forming the sheet using the composition and attaching the sheet to at least one surface of the thermally conductive layer. When the sheet is attached to the heat conduction layer, an adhesive or a pressure-sensitive adhesive may be used if necessary.

The step of applying the electric field to the electric insulating layer is not particularly limited as long as the condition that the thermally conductive anisotropic particles can be aligned in the thickness direction of the electric insulating layer. This step may be performed during or after the formation of the electrically insulating layer. FIG. 2 shows an alignment diagram of anisotropic particles according to application of an electric field.

According to an example, as shown in Fig. 3, electrodes capable of applying electric fields can be provided on the upper and lower portions of the spacer, and an electric field can be applied. At this time, a sheet manufactured using the composition or the composition may be disposed between the electrodes.

According to one example, a thermally conductive electrically insulating layer may be formed by placing a thermally conductive layer between the electrodes, applying the composition on the thermally conductive layer, and then curing the composition while applying an electric field.

The conditions for applying the electric field may be determined according to the composition or composition ratio of the composition, and may be, for example, 1 to 10 kV for 1 to 5 hours. In the case of an electric field, various electric fields such as AC, DC, square, or pulse type can be applied. An electric field of AC rather than DC is desirable. For AC, a level of 1 to 5 kV / mm is preferred. Above 5 kV / mm exceeds the breakdown voltage of the material, an overcurrent may occur

Hereinafter, the above-described embodiments will be described in more detail with reference to the embodiments. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Example  1 to 7

The composition containing the components of Table 1 below was poured into a mold and cured at 80 캜 for 3 hours while applying an electric field (AC 4 kV) to prepare a sheet. The thickness of the sheet was about 1.2 mm.

Boron
Nitride
(BN) 2-ethylhexyl
Acrylate
(EHA) urethane
Oligomer Plasticizer Thermal initiator
Azobis
Isobutylo
Nitrile
(AIBN) Example
1-3 50 wt% 30.9 wt% 2.6 wt% 16.5 wt% 0.26 wt% Example
4, 5 56 wt% 27.2 wt% 2.3 wt% 14.5 wt% 0.295 wt% Example
6, 7 61 wt% 24.1 wt% 2 wt% 12.9 wt% 0.26 wt%

In each example, boron nitride having the maximum particle diameter as shown in Table 2 below was used, and the maximum particle diameter in Table 2 is based on the D50 average particle diameter of the maximum particle of each particle. The thermal conductivity of the prepared sheet was measured, and the results are shown in Table 2, in comparison with the case where no electric field was applied under the same conditions.

The thermal conductivity was measured using the method of ASTM D5470. The sample is placed between the upper and lower metal plates, and the thermal resistance is obtained by using the temperature difference between the upper and lower plates and the heat transfer rate.

Boron
Nitride
(BN) BN maximum particle diameter
(Content, weight ratio) Thermal conductivity (W / mK) Thermal conductivity
Growth rate (%) Electric field O Electric field X Example 1 50 wt% 29 μm: 10 μm
(30:70) 1.50 0.885 69 Example 2 50 wt% 29 μm: 10 μm
(50:50) 3.24 0.854 279 Example 3 50 wt% 29 μm: 10 μm
(70:30) 3.39 0.925 266 Example 4 56 wt% 29 μm: 10 μm
(100: 0) 4.08 0.957 326 Example 5 56 wt% 29 μm: 10 μm
(70:30) 3.60 1.02 253 Example 6 61 wt% 29 μm: 10 μm
(100: 0) 3.62 1.26 187 Example 7 61 wt% 29 μm: 10 μm
(70:30) 1.57 1.38 14

According to the above Table 2, when the particles having the largest diameter are used in a large amount, the thermal conductivity is higher. The thermal conductivity increased with increasing the content of boron nitride particles up to 56 wt% of the particle content, but the effect of increasing the thermal conductivity decreased when the particle content was over 56 wt%.

- 29 μm 100% BN 56 wt% Example 4 Thermal conductivity 4.08 W / mK → 61 wt% (Example 6) Thermal conductivity 3.62 W / mK

When the thermal conductivity is 3.39 W / mK → 56 wt% (Example 5), when the thermal conductivity is 3.60 W / mK → 61 wt% (Example 3) Example 7) Thermal conductivity 1.57W / mK

As a result of observing the degree of grain orientation through XRD analysis of the sheet prepared above, when the electric field was applied as shown in Table 3, the degree of grain orientation was high and the thermal conductivity was also high.

BN
content BN
29 μm: 10 μm
(Weight ratio) Electric field Thermal conductivity
(W / mK)

BN Orientation (%)

Example 4 56wt% 100: 0 O 4.08 74 X 0.957 One Example 2 50wt% 50:50 O 3.24 73 X 0.854 2 Example 1 50wt% 30:70 O 1.50 32 X 0.885 One

Example  8

After the graphite sheet was placed under the mold, the composition used in Example 3 was poured into a mold and cured at 80 캜 for 3 hours while applying an electric field (AC 4 kV) to prepare a heat-radiating sheet. At this time, the thickness of the thermally conductive electric insulating layer was 700 mu m.

Fig. 4 shows the results of Example 8. Fig.

In addition, the boron nitride (BN) orientation degree and the volume resistance are shown in Table 4 when the pressures applied to the samples when measuring the thermal conductivity are 10 Psi and 100 Psi, respectively.

division Thermal conductivity
(W / mK)

BN Orientation (XRD)

Volume resistance
(Ωcm) 10Psi 100Psi Electric field O 2.20 3.96 92.6% 10 ¹⁰ Electric field X 0.823 0.966 1.6% 10 ¹¹ Graphite sheet
(Kaneka 32) an 0.669 1.67 - Energization (measurement not possible)

Claims (14)

A thermally conductive layer and a thermally conductive electrically insulating layer provided on at least one surface of the thermally conductive layer and including a resin and thermally conductive anisotropic particles dispersed in the resin,
The thermally conductive anisotropic particles of the thermally conductive anisotropic layer have a diffraction peak of (100) plane relative to the sum of the integral intensity of the diffraction peak of the (002) plane and the integrated intensity of the diffraction peak of the (100) Wherein the percentage of the integral strength of the electrically insulating heat-radiating sheet is 10% or more. The electrically insulating heat dissipation sheet according to claim 1, wherein the percentage is 30% or more. The electrically insulating heat-radiating sheet according to claim 1, wherein an aspect ratio, which is a ratio of a maximum diameter to a minimum diameter of the thermally conductive anisotropic particles, is 2 or more. The electrically insulating heat dissipating sheet according to claim 1, wherein the thermally conductive anisotropic particles are boron nitride (BN) particles. The electrically insulating heat dissipation sheet according to claim 1, wherein the maximum diameter of the thermally conductive anisotropic particles is 1 μm to 100 μm. The insulating sheet according to claim 1, wherein the content of the thermally conductive anisotropic particles in the thermally conductive electrically insulating layer is 30 wt% to 70 wt%. The electrically insulating heat dissipating sheet according to claim 1, wherein the thermally conductive anisotropic particles comprise two or more kinds of particles having different maximum diameters. The electrically insulating heat dissipating sheet according to claim 1, wherein particles having a maximum particle diameter of 20 m or more are at least 30% by weight of the thermally conductive anisotropic particles. The electrically insulating heat dissipating sheet according to claim 1, wherein the resin is a (meth) acrylic resin. 9. The electrically insulating heat spreading sheet according to claim 8, wherein the resin is a cured product of a polymerizable component comprising an acrylic monomer or a partial polymer thereof and a urethane oligomer. The electrically insulating heat dissipation sheet according to claim 1, wherein the thermally conductive layer is a graphite sheet. Preparing a composition comprising a resin or a precursor of the resin and thermally conductive anisotropic particles;
Applying the composition to at least one surface of the thermally conductive layer or preparing a sheet using the composition and attaching the sheet to at least one surface of the thermally conductive layer to form an electrically insulating layer on at least one surface of the thermally conductive layer; And
Forming a thermally conductive electrically insulating layer by aligning the maximum diameter direction of at least a part of the thermally conductive anisotropic particles parallel to the thickness direction of the electrically insulating layer by applying an electric field during or after the production of the electrically insulating layer
Wherein the heat-radiating sheet is made of a thermosetting resin. The method for producing an electrically insulating heat sink sheet according to claim 12, wherein the resin or the precursor of the resin comprises an acrylic monomer or a partial polymer thereof and a urethane oligomer. [14] The method of claim 12, wherein forming the thermally conductive electrically insulating layer comprises: providing an electrode capable of applying an electric field to upper and lower portions of the spacer; placing a thermally conductive layer between the electrodes; , And the composition is cured in a state of applying an electric field to form a thermally conductive electric insulating layer.

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