TW202003236A - Electronic apparatus and electromagnetic wave-shielding heat dissipation sheet - Google Patents

Abstract

An electronic apparatus according to an aspect of the present invention is provided with an electronic component, an electromagnetic wave-shielding heat dissipation sheet, and a case that accommodates the electronic component and the electromagnetic wave-shielding heat dissipation sheet, wherein the electromagnetic wave-shielding heat dissipation sheet is provided with a first heat conductive resin layer, a conductive layer, and a second heat conductive resin layer in this order, and is disposed such that the first heat conductive resin layer is in contact with the electromagnetic component and the second heat conductive resin layer is in contact with the case.

Description

Electronic equipment and electromagnetic wave shielding heat radiation sheet

The invention relates to an electronic device and electromagnetic wave shielding heat dissipation sheet.

With the miniaturization and weight reduction of electronic components, high-density mounting of electronic components is being promoted. In order to prevent malfunctions and suppress the impact on the human body, the need to shield electromagnetic waves (electromagnetic wave shielding) generated by electronic components is increasing. Previously, as a method of electromagnetic wave shielding, a method of sealing electronic parts in a metal case has been used, but this method requires a space distance between the electronic parts and the case to ensure insulation, thereby becoming miniaturized electronic devices Obstacles. In this regard, as an electromagnetic wave shielding material that replaces a metal case, a sheet-shaped electromagnetic wave shielding material has been proposed (for example, Patent Document 1). [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2014-45047

[Problems to be solved by the invention]

On the other hand, in the electronic equipment as described above, in order to prevent malfunction of the electronic equipment due to the heat generated by the electronic parts, it is also important to dissipate heat to the outside of the electronic equipment. However, the sheet-shaped electromagnetic wave shielding material described in Patent Document 1 does not have heat dissipation, and in order to dissipate heat, it is necessary to additionally provide a heat dissipation member in the electronic device. In this case, since the number of components increases, it becomes difficult to miniaturize the electronic device.

Therefore, the object of the present invention is to miniaturize electronic devices while providing them with electromagnetic wave shielding properties and heat dissipation properties. [Technical means to solve the problem]

The inventors have made intensive research and found that the sheet used in the two areas of the conductive layer with the heat conductive resin layer is arranged in such a way that one heat conductive resin layer contacts the electronic component and the other heat conductive resin layer contacts the housing. This makes it possible to reduce the size of electronic devices while giving them electromagnetic wave shielding properties and heat dissipation.

That is, the present invention can provide the following machines in various aspects. [1] An electronic device including an electronic component, an electromagnetic wave shielding heat dissipation sheet, and a case that houses the electronic component and the electromagnetic wave shielding heat dissipation sheet, and the electromagnetic wave shielding heat dissipation sheet is sequentially provided with a first thermally conductive resin layer and conductive The layer and the second thermally conductive resin layer are arranged such that the first thermally conductive resin layer contacts the electronic component, and the second thermally conductive resin layer contacts the case. [2] The electronic device of [1], wherein the conductive layer is formed of metal foil or metal mesh. [3] The electronic device according to [1] or [2], wherein the conductive layer contains at least one kind 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 contain polysiloxane resin and thermally conductive filler, respectively. [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 comprising a first thermally conductive resin layer, a conductive layer, and a second thermally conductive resin layer in this order. [8] The electromagnetic wave shielding heat dissipation sheet as in [7], wherein the conductive layer is formed of metal foil or metal mesh. [9] The electromagnetic wave shielding heat dissipating 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 heat dissipating sheet according to any one of [7] to [9], wherein the first thermally conductive resin layer and the second thermally conductive resin layer contain polysiloxane resin and thermally conductive filler, respectively. [11] The electromagnetic wave shielding heat dissipating sheet according to [10], wherein the content of the heat conductive filler is 40 to 85% by volume relative to each of the first heat conductive resin layer and the second heat conductive resin layer. [12] The electromagnetic wave shielding heat dissipating sheet according to any one of [7] to [11], wherein a plurality of notches are formed in at least one of the first thermally conductive resin layer and the second thermally conductive resin layer. [Effect of invention]

According to the present invention, it is possible to downsize an electronic device while providing electromagnetic wave shielding properties and heat dissipation properties to the electronic device.

Hereinafter, the embodiments of the present invention will be described in detail while referring to the drawings as appropriate.

FIG. 1 is a schematic cross-sectional view of an electronic device according to an embodiment. As shown in FIG. 1, an electronic device 1 according to an embodiment includes a substrate 2, electronic components 4 provided on the substrate 2 through a plurality of solders 3, and electromagnetic wave shielding heat-dissipating fins (hereinafter, also simply referred to as “heat-dissipating fins Materials") 5 and the housing 6 that houses them.

The substrate 2 may be, for example, a printed substrate or the like. The electronic component 4 may be, for example, LSI (Large Scale Integration), IC (Integrated Circuit), semiconductor package, or the like. The solder 3 electrically connects the wiring in 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 into the substrate 2.

The housing 6 is, for example, a hollow, substantially rectangular parallelepiped box. The housing 6 may be made of metal or resin. The casing 6 may be, for example, a metal casing having electromagnetic wave shielding properties, or a resin casing having no electromagnetic wave shielding properties. The electronic device 1 includes a heat radiation sheet 5 having electromagnetic wave shielding properties. Therefore, even if the housing 6 is not electromagnetic wave shielding (for example, a resin casing), the electromagnetic waves generated by the electronic components 4 can also pass through the heat sink The material 5 is preferably shielded, so that it is difficult to leak to the outside of the electronic device 1.

The heat dissipation sheet 5 includes a conductive layer (conductive base material) 7 and thermally conductive resin layers 8 and 9 respectively stacked on both sides 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 of one embodiment includes a first thermally conductive resin layer 8A, a conductive layer 7, and a second thermally conductive resin layer 9 in this order. The first thermally conductive resin layer 8A, the conductive layer 7 and the second thermally conductive resin layer 9 have substantially the same planar shape (for example, a rectangular shape), and are stacked so that the end surfaces of the layers are aligned with each other to constitute the heat dissipation sheet 5.

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

The conductive layer 7 is preferably formed of metal foil or metal mesh. The conductive layer 7 contains, for example, at least one kind selected from the group consisting of aluminum, copper, silver, and gold as a metal constituting a metal foil or a metal mesh. The metal foil may be aluminum foil, copper foil, silver foil or gold foil. From the viewpoint that a better specific gravity can be obtained and the electromagnetic wave shielding property is more excellent, it is preferably aluminum foil or copper foil.

The metal mesh may be a network in which the fibers of the above-mentioned metal are woven into a mesh, or may be formed by coating a conductive metal with organic fibers or inorganic fibers such as natural fibers or synthetic fibers by plating, sputtering, evaporation, etc. Petitioner. Examples of natural fibers include cotton and hemp. Examples of synthetic fibers include polyester fibers, polyolefin fibers, and aromatic polyamide fibers. Examples of inorganic fibers include carbon fibers and glass fibers. The conductive metal may be the aforementioned aluminum, copper, silver or gold, or 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 from the viewpoint of better flexibility and weight of the heat dissipating sheet 5. 200 μm or less, 100 μm or less, or 50 μm or less.

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

<(A) resin component> (A) Resin component From the viewpoint of obtaining a heat dissipation sheet 5 excellent in flexibility and more excellent in thermal conductivity (heat dissipation), it is preferably (a) a polysiloxane resin component containing a polysiloxane resin.

(a) The polysiloxane resin component is not particularly limited. For example, it may be a component that can be hardened by a hardening reaction caused by peroxide crosslinking, condensation reaction crosslinking, addition reaction crosslinking, ultraviolet crosslinking, etc. It is preferably a component that can be hardened by a hardening reaction initiated by an addition reaction crosslinking. (a) The silicone resin component preferably contains an addition reaction type silicone resin, and more preferably contains a one-liquid addition reaction type or a two-liquid addition reaction type silicone resin.

(a) The polysiloxane resin component preferably contains (a1) an organic polysiloxane having a vinyl group at least at the terminal or side chain (hereinafter, also referred to as "organic polysiloxane having a vinyl group"), And (a2) Two-component addition of organic polysiloxanes having at least two H-Si groups at the terminal or side chain (hereinafter, also referred to as "organic polysiloxanes having H-Si groups.") It is a reactive liquid silicone resin component.

In the (a) silicone resin component, (a1) and (a2) react and harden, thereby forming silicone rubber. By using such (a) silicone resin component together with (B) thermally conductive filler, even when the thermally conductive resin composition contains the thermally conductive filler in a relatively large content of, for example, 40 to 85% by volume Also, a thermally conductive resin layer with high flexibility can be obtained. Furthermore, since a large amount of thermally conductive filler can be contained, a thermally conductive resin layer with high thermal conductivity can be obtained.

(a1) is an organic polysiloxane having a vinyl group at least at any position of the terminal or side chain, and may have either a linear structure or a branched structure. The organopolysiloxane having a vinyl group is, for example, a structure represented by (Si-R) in the molecule of the organopolysiloxane, and a part of the R part is a vinyl group.

(a1) An organic polysiloxane having a vinyl group, specifically, for example, it may have a structural unit represented by the following formula (a1-1) or a terminal structure represented by the formula (a1-2). (a1) The organic polysiloxane having a vinyl group may have, for example, a structural unit represented by formula (a1-1) and a structural unit represented by formula (a1-3), or may have a formula represented by formula (a1-2) ) Represents the terminal structure and the structural unit represented by formula (a1-3). Among them, (a1) the organic polysiloxane having a vinyl group is not limited to those having such structural units or terminal structures. [Chemical 1]

The content of vinyl in (a1) may be 0.01 mol% or more, and may be 15 mol% or less or 5 mol% or less, preferably 0.01-15 mol%, more preferably 0.01-5 mol %. The "vinyl content" in the present invention refers to the ratio (mol%) of the number of moles of vinyl groups to the total number of moles of vinyl groups and Si atoms in (a1).

The vinyl content can be measured by the following method. The vinyl content was determined by NMR (Nuclear Magnetic Resonance). Specifically, for example, using ECP-300 NMR manufactured by JEOL Corporation, the organic polysiloxane having a vinyl group is dissolved and measured in deuterated chloroform as a deuterated solvent. Vinyl when the sum of the number of moles of vinyl calculated from the measurement results and the number of moles of Si atoms (derived from Si-CH ₃ groups, H-Si groups, etc.) is taken as 100 mole% The ratio of moles is used as the vinyl content (mol%).

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

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

(a2) is an organic polysiloxane having at least two H-Si groups at any position on the terminal or side chain, and may have either a linear structure or a branched structure. The organic polysiloxane having an H-Si group is, for example, a structure represented by (Si-R) in the molecule of the organic polysiloxane, and a part of the R part is H (hydrogen atom).

(a2) An organic polysiloxane having an H-Si group, specifically, for example, may have a structural unit represented by the following formula (a2-1) or a terminal structure represented by the formula (a2-2). (a2) The organic polysiloxane having an H-Si group may have, for example, a structural unit represented by formula (a2-1) and a structural unit represented by formula (a2-3), or may have a formula (a2) -2) The terminal structure represented by and the structural unit represented by formula (a2-3). Among them, (a2) the organic polysiloxane having an H-Si group is not limited to those having such structural units or terminal structures. [Chem 2]

The content of the H-Si group in (a2) may be 0.01 mol% or more, and may be 15 mol% or less or 5 mol% or less, preferably 0.01-15 mol%, more preferably 0.01-5 Moore%. The "content of H-Si group" in the present invention refers to the ratio (mol%) of the mole number of the H-Si group to the mole number of the Si atom in (a2).

The content of the H-Si group can be measured by the following method. The H-Si group content was measured by NMR. Specifically, for example, using ECP-300 NMR manufactured by JEOL Corporation, an organic polysiloxane having an H-Si group is dissolved in deuterated chloroform as a deuterated solvent and measured. When the molar number of Si atoms (derived from Si-CH ₃ groups, H-Si groups, etc.) calculated from the measurement results is set to 100 mol %, the ratio of the molar number of H-Si groups is given by It is the content of H-Si group (mol%).

(a2) The organic polysiloxane having an H-Si group is preferably an alkyl polysiloxane 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 (for example, methyl, ethyl, etc.), and more preferably methyl. (a2) The organic polysiloxane having an H-Si group may be a methyl polysiloxane having two or more H-Si groups at the terminal and/or side chain.

(a2) The mass average molecular weight of the organic polysiloxane with H-Si group is preferably 400,000 or less, 200,000 or less, and 10,000 or more or 15,000 or more, more preferably 10,000 to 200,000, and further preferably 15,000 ~200,000. (a2) The mass average molecular weight of the organopolysiloxane having an H-Si group can be measured by the method described in the examples.

(a1) Organic polysiloxane with vinyl group and (a2) Organic polysiloxane with H-Si group may be further contained in the side chain of the polysiloxane skeleton with phenyl, trifluoropropyl, etc. Other structures of organic groups. The structural unit with other structure may be a structural unit derived from phenylmethylsiloxane and diphenylsiloxane. The organic polysiloxane constituting (a) the polysiloxane resin may also be a modified organic polysiloxane having functional groups such as epoxy groups.

(a) The viscosity of the silicone component at 25°C may be 100 mPa·s or more or 350 mPa·s or more, and may be 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, more preferably 350 to 2,000 mPa·s. If (a) the viscosity of the silicone component at 25°C is 100 mPa·s or more, it is more advantageous in terms of suppressing cracking of the thermally conductive resin layer. If (a) the silicone component is When the viscosity at 25°C is 2,500 mPa·s or less, it is advantageous in that it is easy to highly fill the thermally conductive filler.

(a) The viscosity of the silicone component at 25°C can be measured using, for example, a B-type viscometer "RVDVIT" manufactured by BROOKFIELD. Using the f-axis as the main shaft, the viscosity at 20 rpm was measured.

(a) The polysiloxane resin component is preferably a thermosetting organic polysiloxane. (a) The polysiloxane resin component may contain a curing agent (crosslinkable organic polysiloxane) in addition to polyorganopolysiloxane (base polymer, also called main agent). (a) The polysiloxane resin component may further contain an addition reaction catalyst to promote the addition reaction.

As the silicone resin component (a) as described above, a commercially available product can be used. The commercially available polysiloxane resin component is used as a two-component addition reaction type liquid silicone rubber, for example, "TSE-3062" "X14-B8530" manufactured by Meitu Corporation, and "SE" manufactured by Toray Dow Corning Corporation. -1885A/B” etc., but not limited to the scope of these specific commercially available products.

(A) The resin component may contain other resins, such as an acrylic resin and an epoxy resin, in addition to the above-mentioned (a) polysiloxane resin component.

(A) The content of the resin component ((a) silicone resin component) relative to the total volume of the thermally conductive resin layer may be 10% by volume or more or 15% by volume, and may be 65% by volume or 60% by volume Hereinafter, it is preferably 10 to 65% by volume, and more preferably 15 to 60% by volume. If the content of the (A) resin component ((a) polysiloxane resin component) is 10% by volume or more, flexibility can be improved, and if it is 65% by volume or less, it is advantageous in terms of avoiding reduction in thermal conductivity.

<(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 can be alumina, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, aluminum metal, graphite, etc. As the thermally conductive filler, one type or the like may be used alone or in combination of two or more types. The thermally conductive filler is preferably spherical (preferably with a sphericity of 0.85 or more).

In order to exhibit higher thermal conductivity while having good filling property to the resin, the thermally conductive filler is preferably alumina. Alumina (hereinafter also referred to as "alumina") can also be flame spraying method by aluminum hydroxide powder, Bayer method, ammonium alum thermal decomposition method, organoaluminum hydrolysis method, aluminum water discharge method, It is manufactured by any method such as freeze-drying method. Alumina is preferably manufactured by flame spraying of aluminum hydroxide powder in terms of control of particle size distribution and particle shape control.

The crystal structure of aluminum oxide may be either a single crystal or a polycrystal. The crystal phase of aluminum oxide is preferably an α phase in terms of high thermal conductivity. The specific gravity of aluminum oxide can prevent the increase of the ratio of voids and low crystal phases existing inside the aluminum oxide particles, and further improve the thermal conductivity (for example, 2.5 W/m·K or more) , Preferably 3.7 or more.

The aluminum oxide is preferably spherical. In the case where the aluminum oxide is spherical, the sphericity of the aluminum oxide is preferable from the viewpoint of suppressing the decrease in fluidity and causing the filler to segregate in the thermally conductive resin layer, and the change in physical properties becomes larger as it becomes larger It is 0.85 or more. Aluminum oxide with a sphericity of 0.85 or more can be obtained as a commercially available product, for example, spherical aluminum oxide DAW45S (trade name), spherical aluminum oxide DAW05 (trade name) manufactured by Denka Co., Ltd. , Spherical aluminum oxide ASFP20 (trade name), etc.

The thermally conductive filler preferably has a maximum value (peak value) within a particle size distribution 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 thermally conductive filler can be adjusted by the classification and mixing operations of the thermally conductive filler.

The thermally conductive filler is preferably included in the thermally conductive filler (B-1) having a maximum value (peak value) within a range of particle size of 10 μm or more and 100 μm or less, and a particle size of 1 μm or more and less than 10 μm The thermally conductive filler (B-2) having a maximum value (peak value) in the range and the thermally conductive filler (B-3) having a maximum value (peak value) in a range where the particle size is less than 1 μm. The thermally conductive filler (B-1) may be a thermally conductive filler having an average particle size of 10 μm or more and 100 μm or less. The thermally conductive filler (B-2) may be a thermally conductive filler having an average particle size of 1 μm or more and less than 10 μm. The thermally conductive filler (B-3) may be a thermally conductive filler having an average particle size of less than 1 μm. The particle size distribution and average particle size of the thermally conductive filler can be measured by the method described in the examples.

The ratio of the thermally conductive filler (B-1) relative to the total volume of the thermally conductive filler is preferably 15% by volume or more, 20% by volume or more, 30% by volume or more, or 40% by volume or more, and 70% by volume % Or less, 60% by volume or less, or 50% by volume or less, more preferably 20 to 60% by volume.

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

The ratio of the thermally conductive filler (B-3) relative to the total volume of the thermally conductive filler may be 5 vol% or more or 8 vol% or more, and may be 30 vol% or less, 25 vol% or less, 20 vol% or less or 15 Below vol%, preferably 5-30 vol%, more preferably 8-20 vol%.

The content of the thermally conductive filler relative to the total volume of the thermally conductive resin layer may be 20% or more or 30% or more, preferably 35% or more or 40% or more, and 95% or 80% or less % Or less, preferably 85% by volume or less, and more preferably 40 to 85% by volume. If the content of the thermally conductive filler is 35% by volume or more, the thermal conductivity of the thermally conductive resin layer becomes better. If the content of the thermally conductive filler is 85% by volume or less, the fluidity of the thermally conductive resin composition can be easily avoided, and the thermally conductive resin layer can be easily produced.

The thermally conductive resin composition may further contain reaction retardants such as acetyl alcohols and maleates, tackifiers such as Aerotech and silicone powders with a particle size of ten to hundreds of μm, flame retardants, pigments, and the like.

The thicknesses of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 may be 0.1 mm or more and 10 mm or less, respectively. The thermal conductivity 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, may be 1 mm or more or 1.5 mm or more, and may be 15 mm or less or 12 mm or less, preferably 10 mm or less, or 0.2 mm to 10 mm. If the thickness of the heat dissipation sheet 5 is 0.2 mm or more, it is possible to suppress the increase in the surface roughness caused by the thermally conductive filler and the consequent decrease in thermal conductivity. If the thickness of the heat dissipation sheet 5 is 10 mm or less, the reduction 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 higher thermal conductivity and has 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 in terms of excellent operability when the heat dissipation sheet 5 is processed.

The heat dissipation sheet 5 can be manufactured by, for example, a manufacturing method including the steps of disposing a thermally conductive resin composition on one surface of the conductive layer 7 to form one of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 Step (a-1), and the other step (a-2) of disposing the thermally conductive resin composition on the other surface of the conductive layer 7 to form the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 ).

In another embodiment, the manufacturing method of the heat dissipation sheet 5 may further include the following steps: disposing a thermally conductive resin composition on a resin film (for example, PET (Polyethylene Terephthalate, polyethylene terephthalate) film, etc.), Step (b-1) of forming one of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9, the first thermally conductive resin layer 8 or the second thermal conduction formed in the step (b-1) The step (b-2) of providing (for example laminating) the conductive layer 7 on the conductive resin layer 9 and the thermal conductive resin composition on the conductive layer 7 provided in the step (b-2) to form the first heat conduction Step (b-3) of the other of the resin layer 8 and the second thermally conductive resin layer 9.

The thermally conductive resin composition used in the production method of each embodiment can be obtained by a known method, for example, it can be obtained by mixing components (A) and (B). Mixers such as roll mills, kneaders, and Banbury mixers are used for mixing.

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

In step (a-1), step (a-2), step (b-1) and step (b-3), for example, the first thermally conductive resin can be formed by heating and curing the thermally conductive resin composition Layer 8 or second thermally conductive resin layer 9.

The heating hardening is carried out using an ordinary hot air dryer, far infrared dryer, microwave dryer, etc. The heating temperature is preferably 50 to 200°C. If the heating temperature is 50° C. or higher, crosslinking is easily performed sufficiently, and if it is 200° C. or lower, deterioration due to heating can be suppressed. The heat hardening time is preferably 2 to 14 hours.

In another embodiment of the heat dissipation sheet 5, cutouts (plural cutout lines) may be formed on the surfaces of the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9 (the surface opposite to the conductive layer 7) . Fig. 3 is a perspective view showing a heat dissipation sheet of another embodiment. As shown in FIG. 3, in this heat dissipation sheet 5B, the surface of the first thermally conductive resin layer 8B (the surface on the side opposite to the conductive layer 7) has cutouts 10 (plural cutout lines). 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, only one of the thermally conductive resin layers (the first thermally conductive resin layer 8) is formed with cutouts 10, and in another embodiment, both of the thermally conductive resin layers ( Both the first thermally conductive resin layer 8 and the second thermally conductive resin layer 9) are formed with cutouts.

However, with the previous thermally conductive sheet, there is a case where the thermally conductive resin layer is provided with grooves (grooves having a specific width), so that the thermally conductive sheet is sandwiched between the electronic part and the case In this case, there is a possibility that air that cannot be discharged remains in the groove of the thermally conductive resin layer, which may increase the thermal resistance (decrease in thermal conductivity). In this regard, when the heat dissipation sheet 5B is sandwiched between the electronic component 4 and the case 6, since the heat conductive resin layers 8, 9 are provided with cutouts, the layers of the heat dissipation sheet 5B can be laminated The rebound force (force in the compression direction) generated in the direction escapes to the direction perpendicular to the stacking direction, so that the air also becomes difficult to enter.

In addition, the heat dissipation sheet 5B has a high followability to the shape of the application object, so it is difficult to apply an excessive load to the electronic parts 4 and the case 6, thereby reducing the risk of damage. In addition, even when the electronic component 4 and the case 6 have irregularities, the heat dissipation sheet 5B follows the irregularities and exerts high adhesion. In this way, since the heat dissipation sheet 5B is excellent in adhesion, the heat generated in the electronic component 4 can be dissipated more efficiently, thereby exhibiting more excellent heat dissipation.

According to the above, the heat dissipation sheet 5B is particularly suitable for applications where a load is applied between the electronic component 4 and the case 6 to be sandwiched. Therefore, the heat dissipation sheet 5B is preferably a non-adhesive sheet (non-adhesive sheet with non-adhesive heat conductive resin layers 8 and 9) that does not have adhesive properties.

From the viewpoint of preferably obtaining the effect of the cut 10 as described above, the cut 10 may be constituted by a linear cut of 1 or more (hereinafter referred to as "cut line"). The width of this cut line is, for example, the extent to which the streaks of the cutting marks are visible. Regarding the width of the cut line (length in the short side direction), it is difficult for air to enter the heat dissipation sheet 5B, which can further increase the thermal conductivity (further reduce the thermal resistance), and at the same time can further improve the flexibility and followability of the heat dissipation sheet 5B. From a viewpoint, the smaller the better, preferably 300 μm or less, more preferably less than 300 μm, further preferably 100 μm or less, and particularly preferably 50 μm or less. The width of the notch line (length in the short side direction) may be 2 μm or more, preferably 2 μm or more and less than 300 μm, more preferably 2 μm or more and 50 μm or less.

The notch line may be linear, for example, and may be curved or meandering. 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 cutout 10 is a lattice. That is, the notch 10 shown in FIG. 3 can be configured by arranging a plurality of straight notch lines in a lattice shape when viewed from above. The planar shape of each quadrilateral constituting the lattice may be, for example, rectangular, square, or the like.

In another embodiment, the plane shape of the cut may also be linear, dashed (suture hole shape), polygonal, elliptical, circular, or the like.

The dotted line (seam hole shape) refers to, for example, arranging a plurality of straight cut lines at specific intervals (the parts with cut lines and the parts without cut lines are alternately repeated) in one direction (the extending direction of the cut lines) and Into the shape.

The polygon is not particularly limited, and examples include triangles, quadrilaterals, pentagons, hexagons, and stars. Examples of quadrilaterals include trapezoids, rhombuses, and parallelograms.

The planar shape of the cut 10 is preferably linear, wavy, diamond, circular, star and lattice, and more preferably linear, diamond and lattice, in terms of workability and high followability during the cutting process In other words, it is more preferably lattice-shaped (in particular, the planar shape of each quadrilateral constituting the lattice is a square lattice-shaped).

The vertical cross-sectional shape of the notch 10 (shape viewed from a direction perpendicular to the stacking direction of the layers constituting the heat dissipation sheet 5B) is not particularly limited, and may be, for example, V-shaped, Y-shaped, or L-shaped (English lowercase letter l ) Shape (straight line shape), inclined (oblique line) shape, etc., from the viewpoint that it is easy to form the cutout 10 even in the state where the layers constituting the heat dissipation sheet 5B have been stacked, the shape of L (English lowercase letter l) is preferred (Always linear).

The notch 10 is preferably not penetrated (in the heat conductive resin layers 8 and 9, it does not penetrate in the thickness direction (stacking direction)). The length of the unpenetrated portion (the length in the thickness direction (stacking direction) of the portion where the cut is not formed in the thermally conductive resin layers 8 and 9) may be 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, or 0.25 mm or more And may be 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 0.15 mm to 5.0 mm, and further preferably 0.2 mm to 4.0 mm, especially It is preferably 0.25 mm to 3.0 mm.

The ratio of the depth of the notch 10 (the length of the notch 10 in the thickness direction (stacking direction) of the thermally conductive resin layers 8, 9) to the thickness of the thermally conductive resin layers 8, 9 is preferably 2% or more, 10% or more, 20% or more, 30% or more, or 40% or more, and preferably 90% or less, 80% or less, or 70% or less, preferably 2% to 90%, more preferably 30% to 80% It is further preferably 40% to 70%. When the ratio is in the above range, high flexibility and high followability can be easily obtained (for example, the compression stress (when the compression ratio is 20%) can be reduced by more than 5% compared with the case where no cut is provided), and it can be further Reduce thermal resistance (can further improve thermal conductivity).

The notch 10 can be formed by using a cutting device, for example, by combining any one of the thickness direction (stacking direction) and the direction perpendicular thereto, and moving the cutting device. In addition, the cutting device can also move in any direction (shape) such as "inclined direction" or "wave shape".

The cutting device may be, for example, a cutting edge, a laser, a water jet (water jet cutter), etc. In order to easily make the cutting line narrow and easy to process, the cutting edge is preferred. The method of forming the cut 10 may be slit processing by a cutting edge, processing by a laser knife, or the like.

In the case where a cut is made in the heat dissipation sheet 5, it is preferable that the difference in ASKER C hardness before and after cutting is preferably 2 or more, more preferably 5 or more. If the difference between the ASKER C hardness before and after cutting is 2 or more, the effect of improving flexibility is easily obtained, and the followability becomes more favorable. This "difference between 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 cutouts, it is preferable to bring the thermally conductive resin layer formed with the cutouts into contact with the electronic component 4. In other words, it is preferable that the electromagnetic wave shown in FIG. 3 is formed when any one of the first thermally conductive resin layer 8 in contact with the electronic component 4 and the second thermally conductive resin layer 9 in contact with the housing 6 forms the cutout 10. The shielding heat dissipation sheet 5B forms a cutout 10 in contact with the first thermally conductive resin layer 8 of the electronic component 4.

In this case, the heat dissipation sheet 5B can follow the shape of the contact surface of the electronic component 4 with the first thermally conductive resin layer 8 by high followability, and at the same time by the high flexibility, even at the heat dissipation sheet 5B When stress is applied, the stress can be relieved, so that the electronic component 4 is not easily damaged. In addition, since the heat dissipation sheet 5B has high flexibility and high followability, it also has high thermal conductivity, so that heat generated from the electronic component 4 can be particularly efficiently transferred to the housing 6. Therefore, the electronic device 1 can efficiently release the heat from the electronic component 4 to the outside of the electronic device 1.

In the electronic device 1 described above, the electromagnetic wave shielding heat dissipation sheet 5 has electromagnetic wave shielding properties, and therefore can block electromagnetic waves generated from the electronic component 4 while blocking electromagnetic waves from the outside. In addition, the electromagnetic wave shielding heat dissipation sheet 5 also has insulation, so even if the space distance between the electronic component 4 and the housing 6 is narrow, the electronic device 1 can be miniaturized. In addition, although the electromagnetic shielding performance can be further improved when the housing 6 is a metal housing, the electromagnetic shielding can be achieved by the electromagnetic shielding heat dissipation sheet 5, so there is no need to use a metal housing, by using heat dissipation It can also contribute to further miniaturization by replacing it with a chip or the like to ensure heat dissipation.

On the other hand, it has been difficult to reduce the size of the aforementioned electronic devices as described above. Fig. 4 is a schematic cross-sectional view of a conventional electronic device. As shown in FIG. 4, the electromagnetic wave shielding heat dissipation sheet is not provided in the previous electronic device 11, and the housing 16 releases the heat generated by the electronic part 4 to the electromagnetic wave generated by the electronic part 4 while blocking The exterior of the electronic machine 11. In this case, from the viewpoint of obtaining electromagnetic wave shielding and heat dissipation, the housing 16 is made of metal. To ensure the insulation between the electronic component 4 and the housing 16, the space between the electronic component 4 and the housing 16 is required distance. Therefore, it has been difficult to reduce the size of the previous electronic device 11.

As described above, the electronic device 1 provided with the electromagnetic wave shielding heat dissipation sheet 5 of this embodiment can suppress malfunctions and noise caused by electromagnetic waves. In addition, it is possible to provide an electronic component 4 that can reduce the life loss, malfunction, and malfunction of the electronic component 4 caused by temperature rise or strain of the housing.

In addition, according to an embodiment, an electromagnetic wave shielding heat dissipation sheet 5B having both electromagnetic wave shielding properties and thermal conductivity, and also reducing compressive load (stress), and having high followability for application objects such as electronic parts 4 can be provided. In addition, the heat dissipation sheet 5B is provided with cutouts 10 instead of so-called grooves, so that no air remains, and since the followability to the application object such as the electronic component 4 is also high and the adhesion is also high, the heat is dissipated Sex is also higher. The heat dissipation sheet 5B is particularly preferably used 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 that requires adhesion between the heat generating surface of the semiconductor element and the heat dissipating surface of the heat dissipating sheet or the like. The heat dissipation sheet 5B can be preferably used for electromagnetic wave shielding materials and heat conduction members such as industrial components, and can be particularly preferably used as a highly thermally conductive sheet and heat dissipation member with high flexibility that can reduce the compressive stress during installation . Examples

Hereinafter, the present invention will be described in detail by Examples and Comparative Examples. Furthermore, the present invention is not limited to the following examples.

Add (a1) an organic polysiloxane having a vinyl group and (a2) an organic polysiloxane having an H-Si group as the two-component addition reaction type silicone (A) shown below The resin component and (B) thermally conductive filler are mixed at the compounding ratio (volume %) described in Tables 1 to 3 to prepare a thermally conductive resin composition. In addition, the total amount of component (A) and component (B) is set to 100% by volume.

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

In addition, the mass average molecular weight of polyorganosiloxane is the value converted from polystyrene calculated based on the results of gel permeation chromatography analysis. The separation was carried out in a non-aqueous porous gel (polystyrene-xylene copolymer) using toluene as the mobile phase, and a differential refractometer (RI) was used for the detection.

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

In addition, the average particle diameter of the thermally conductive filler was measured using "laser diffraction type particle size distribution measuring device SALD-20" manufactured by Shimadzu Corporation. Regarding the evaluation sample, 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 dispersed with an ultrasonic cleaner for 10 minutes. The solution of the heat conductive filler powder after the dispersion treatment is added dropwise to the sampler part of the device using a dropper, and the measurement is performed after the absorbance is stabilized. The particle size distribution is calculated by the laser diffraction type particle size distribution measuring device based on the data of the light intensity distribution of the diffracted/scattered light generated 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 relative particle amount (100%). Furthermore, the average particle diameter is the average diameter of the particles, and the cumulative weight average D50 (or median particle diameter) as the maximum value or peak value can be obtained. Furthermore, D50 is the particle size with the highest occurrence rate.

Then, the obtained thermally conductive resin composition was disposed on one surface of each conductive layer shown in Tables 1 and 2 in such a manner that a thickness of the thermally conductive resin layer shown in Tables 1 and 2 was obtained using a doctor blade (method). , Heat curing at 110°C for 8 hours. Thereafter, after disposing the thermally conductive resin composition on the other surface of the conductive layer in the same manner as described above, heat curing was performed at 110° C. for 8 hours. With this, the heat dissipation sheets of Examples 1 to 9 and Comparative Example 1 were produced.

Moreover, in Examples 10-14, the heat conductive resin layer of one or both of the heat dissipation sheets obtained in Example 8 was notched. More specifically, a notch blade is used to form a straight-line notch line in one or both of the thermally conductive resin layers in two directions perpendicular to each other to form a lattice-like notch. In addition, the width of the cut line (length in the short side direction) is 50 μm or less, the planar shape of each quadrilateral constituting the lattice is a square of 1.5 mm×1.5 mm, and the number of quadrilaterals constituting the lattice is ² 100 per 15 mm . The ratio of the depth to the depth of the cut (length in the thickness direction) and the thickness of the thermally conductive resin layer are shown in Table 3.

The obtained heat-dissipating sheets were evaluated by the following methods. The results are shown in Tables 1-3.

<Electromagnetic wave shielding property> Using 130×130 mm heat dissipation sheet, the electromagnetic wave shielding effect at 1 MHz was measured by KEC (Kansai Electronic Industry Development Center, Kansai Electronic Industry Development Center) method. If the shielding effect is 10 dB or more, it can be said to be excellent in electromagnetic wave shielding properties, and if it is 20 dB, it can be said to be particularly excellent.

<Thermal conductivity> A sample made of TO-3 type heat dissipation sheet is sandwiched between a TO-3 type copper heater housing (effective area of 6.0 cm ² ) with a built-in transistor and a copper plate. With a load of 10% of the thickness compressed, apply 15 W to the transistor and hold it for 5 minutes. Thereafter, the temperature (°C) of each of the heater casing side and the copper plate side was measured. According to the measurement results, the thermal resistance is determined by the following formula: Thermal resistance (°C/W) = (temperature of heater shell side (°C)-temperature of copper plate side (°C))/power (W) Then, use the above Thermal resistance, the thermal conductivity is calculated by the following formula: Thermal conductivity (W/m·K) = thickness of sample (m)/(cross-sectional area (m ² ) × thermal resistance (℃/W)) if thermal conductivity When it is 0.5 W/m·K or more, it can be said to be excellent in thermal conductivity, and if it is 2 W/m·K or more, it is even more excellent, and if it is 4 W/m·K or more, it can be called particularly excellent.

＜ASKER C hardness＞ The ASKER C hardness is measured by "ASKER Rubber Hardness Tester Type C" manufactured by Macrometer Co., Ltd. If the ASKER C hardness is less than 40, the heat sink sheet has high flexibility, and if the ASKER C hardness is 15 or less, it can be said that the heat sink sheet has particularly high flexibility.

Regarding Examples 10 to 14, the evaluation of the following compressive stress was also carried out. And the results are shown in Table 3. <Compression stress> After the heat sink sheet is punched out to 60×60 mm, the load (N) at a compression rate of 20% is measured for the thickness with a table tester (EZ-LX manufactured by Shimadzu Corporation) and used as compression Stress (N). Furthermore, the compression stress reduction rate is calculated by the following formula: Compression stress reduction rate (%) = {change in thickness due to compression (mm) x 100}/thickness before compression (mm) If the reduction rate of compressive stress is more than 5%, it can be said that the compressive stress can be better reduced.

[Table 1]

[Table 2]

[table 3]

Regarding Examples 1 to 4, according to the type and thickness of the conductive layer, a heat dissipation sheet having high electromagnetic wave shielding properties can be obtained. In addition, regarding Examples 5 to 9, regardless of the molecular weight of the polysiloxane resins of the components (A) and (B), and the amount of the thermally conductive filler, a heat dissipation sheet having high electromagnetic wave shielding properties can be obtained. On the other hand, in Comparative Example 1, although heat dissipation and flexibility can be imparted, insulating PET is used, so electromagnetic wave shielding properties cannot be obtained.

Regarding Examples 10 to 14, by forming a notch, an electromagnetic wave shielding heat-dissipating sheet having reduced compressive stress can be obtained (again, the compressive stress of the heat-dissipating sheet of Example 8 where no notch is formed is 226 N) . Furthermore, even if a cut is formed in one of the thermally conductive resin layers and either of them, a flexible heat dissipation sheet having a compression stress reduction rate of 5% or more can be obtained. [Industry availability]

The electromagnetic wave shielding heat dissipation sheet of the present invention has both high electromagnetic wave shielding properties and thermal conductivity, and also reduces the compressive load (compressive stress) when using the sheet, and has a high followability to the applicable object. The electromagnetic wave shielding heat dissipation sheet of the present invention can be preferably applied to electromagnetic wave shielding and heat dissipation members of electronic parts. In particular, it can provide better electromagnetic wave shielding heat dissipation sheet for electric power related parts of automobiles (car navigation and radio frequency, automatic operation related devices, etc.).

1‧‧‧Electronic machine 2‧‧‧ substrate 3‧‧‧ solder 4‧‧‧Electronic parts 5‧‧‧Electromagnetic shielding heat dissipation sheet 5A‧‧‧radiation sheet 5B‧‧‧radiation sheet 6‧‧‧Housing 7‧‧‧conductive layer 8‧‧‧The first thermally conductive resin layer 8A‧‧‧The first thermally conductive resin layer 8B‧‧‧The first thermally conductive resin layer 9‧‧‧The second thermally conductive resin layer 10‧‧‧cut 11‧‧‧Electronic machine 16‧‧‧Housing

FIG. 1 is a schematic cross-sectional view of an electronic device according to an embodiment. Fig. 2 is a perspective view showing an electromagnetic wave shielding heat dissipation sheet according to an embodiment. Fig. 3 is a perspective view showing an electromagnetic wave shielding heat dissipation sheet of another embodiment. FIG. 4 is a schematic cross-sectional view of a conventional electronic device.

1‧‧‧Electronic machine

2‧‧‧ substrate

3‧‧‧ solder

4‧‧‧Electronic parts

5‧‧‧Electromagnetic shielding heat dissipation sheet

6‧‧‧Housing

7‧‧‧conductive layer

8‧‧‧The first thermally conductive resin layer

9‧‧‧The second thermally conductive resin layer

Claims (12)

An electronic machine with: Electronic parts, Electromagnetic wave shielding heat dissipation sheet, and A housing that houses the electronic components and the electromagnetic wave shielding heat dissipation sheet; and The electromagnetic wave shielding heat dissipation sheet includes a first thermally conductive resin layer, a conductive layer, and a second thermally conductive resin layer in sequence, and the first thermally conductive resin layer contacts the electronic component, and the second thermally conductive resin layer contacts the case Configuration. The electronic device according to claim 1, wherein the conductive layer is formed of metal foil or metal mesh. The electronic device according to claim 1 or 2, wherein the conductive layer contains at least one selected from the group consisting of aluminum, copper, silver, and gold. The electronic device according to any one of claims 1 to 3, wherein the first thermally conductive resin layer and the second thermally conductive resin layer contain a polysiloxane resin and a thermally conductive filler, respectively. The electronic device according to claim 4, wherein the content of the thermally conductive filler is 40 to 85% by volume relative to each of the first thermally conductive resin layer and the second thermally conductive resin layer. The electronic device according to any one of claims 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. An electromagnetic wave shielding heat dissipation sheet includes a first thermally conductive resin layer, a conductive layer, and a second thermally conductive resin layer in this order. The electromagnetic wave shielding heat dissipation sheet according to claim 7, wherein the conductive layer is formed of metal foil or 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 dissipating sheet according to any one of claims 7 to 9, wherein the first thermally conductive resin layer and the second thermally conductive resin layer contain a polysiloxane resin and a thermally conductive filler, respectively. The electromagnetic wave shielding heat dissipation sheet 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. 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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