JP2022121838A - Thermally conductive sheet supply form and thermally conductive sheet body - Google Patents

Abstract

To provide a heat conductive sheet having a tacky surface.SOLUTION: In the supply form 1 of a heat conductive sheet, a heat conductive sheet body 3 is sandwiched between release films 2, and the surface of the heat conductive sheet body 3 immediately after peeling the release film 2 from the heat conductive sheet body 3 has tackiness.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present technology relates to a supply form of a thermally conductive sheet and a thermally conductive sheet body.

2. Description of the Related Art As electronic devices become more sophisticated, semiconductor elements are becoming more dense and highly mounted. Along with this, it is important to more efficiently dissipate the heat generated from the electronic components that make up the electronic equipment. For example, in order to efficiently dissipate heat in a semiconductor device, an electronic component is attached to a heat sink such as a heat dissipating fan or a heat dissipating plate via a heat conductive sheet. As a thermal conductive sheet, for example, a silicone resin containing (dispersing) a filler such as an inorganic filler is widely used. A further improvement in thermal conductivity is required for a heat dissipating member such as this heat conductive sheet. For example, in order to increase the thermal conductivity of the thermally conductive sheet, it is being studied to increase the filling rate of the inorganic filler blended in the matrix such as the binder resin. However, increasing the filling rate of the inorganic filler impairs the flexibility of the thermal conductive sheet or causes powder to fall off, so there is a limit to increasing the filling rate of the inorganic filler.

Examples of inorganic fillers include alumina, aluminum nitride, and aluminum hydroxide. For the purpose of high thermal conductivity, the matrix may be filled with scaly particles such as boron nitride or graphite, carbon fibers, or the like. This is due to the anisotropy of the thermal conductivity of the scaly particles and the like. For example, carbon fibers are known to have a thermal conductivity of about 600 to 1200 W/m·K in the fiber direction. Boron nitride has a thermal conductivity of about 110 W/m·K in the plane direction and a thermal conductivity of about 2 W/m·K in the direction perpendicular to the plane direction. Are known. In this way, the surface direction of the carbon fibers and scale-like particles is made to be the same as the thickness direction of the sheet, which is the heat transfer direction. A dramatic improvement in conductivity can be expected.

Patent Literature 1 describes a thermally conductive sheet in which boron nitride is oriented in the thickness direction. In such a thermally conductive sheet, for example, the anisotropic material can be oriented in the thickness direction of the thermally conductive sheet by forming a molded block from the resin composition for forming the thermally conductive sheet and slicing it. However, when a heat conductive sheet is produced by slicing a molded block in this way, there is a problem that the surface of the heat conductive sheet lacks tackiness. In this way, if the surface of the heat conductive sheet does not have tackiness, there is a risk that the heat conductive sheet will be misaligned when mounted.

International publication WO2019/026745

The present technology has been proposed in view of such conventional circumstances, and provides a heat conductive sheet having a tacky surface.

The present technology is a supply form of a heat conductive sheet sandwiched between release films, and the surface of the heat conductive sheet main body immediately after the release film is peeled off from the heat conductive sheet main body has tackiness.

The heat conductive sheet body according to the present technology contains a binder resin and scaly boron nitride, the scaly boron nitride is oriented in the thickness direction of the conductive sheet body, and both sides of the heat conductive sheet body have tackiness. have

According to the present technology, it is possible to provide a heat conductive sheet having a tacky surface.

FIG. 1 is a cross-sectional view showing an example of a supply form of a heat conductive sheet. FIG. 2 is a cross-sectional view showing an example of a heat conductive sheet main body that constitutes a supply form of the heat conductive sheet. FIG. 3 is a perspective view schematically showing scale-like boron nitride having a hexagonal crystal shape, which is an example of a thermally conductive material having shape anisotropy. FIG. 4 is a cross-sectional view showing an example of a heat conductive sheet main body. FIG. 5 is a cross-sectional view showing an example of a semiconductor device to which a heat conductive sheet body is applied. FIG. 6 is a diagram for explaining a method of evaluating whether or not the aluminum plate slides down when the heat conductive sheet main body is placed on the aluminum plate and shifted by 90°.

In this specification, the average particle size (D50) of the thermally conductive material is the cumulative curve of the particle size value from the small particle size side of the particle size distribution when the entire particle size distribution of the thermally conductive material is 100%. is the particle diameter when the cumulative value is 50%. In addition, the particle size distribution (particle size distribution) in this specification is determined by volume. Examples of the method for measuring the particle size distribution include a method using a laser diffraction particle size distribution analyzer.

[First embodiment]
<Supply form of thermally conductive sheet>
In the first embodiment of the present technology, a heat conductive sheet body is sandwiched between peeling films (films subjected to peeling treatment), and the heat conductive sheet body immediately after peeling the peeling film from the heat conductive sheet body. This is a supply form of a heat conductive sheet having a tacky surface. In this way, in the supply form of the heat conductive sheet according to the present technology, the surface of the heat conductive sheet body immediately after peeling the release film from the heat conductive sheet body has tackiness, so the position at the time of mounting of the heat conductive sheet body Displacement can be suppressed.

For example, in the form of supply of the heat conductive sheet, the tack force of the heat conductive sheet main body immediately after peeling off the release film may be 75 gf or more, or may be 80 gf or more in the following measurement method.
Measurement method: Immediately after peeling off the release film from the supply form of the heat conductive sheet, a probe with a diameter of 5.1 mm is pushed into the heat conductive sheet body by 50 µm at 2 mm/sec and pulled out at 10 mm/sec.

Here, "immediately after peeling the release film from the main body of the heat conductive sheet" is not particularly limited, but means, for example, within 5 minutes after peeling the release film.

In addition, the heat conductive sheet is preferably supplied such that the tack force of the heat conductive sheet main body sandwiched between the release films is greater than the tack force of the heat conductive sheet not sandwiched between the release films. For example, after preparing a supply form of a thermally conductive sheet in which the main body of the thermally conductive sheet is sandwiched between release films, it is left for 7 days, and immediately after the release film of the supply form of this thermally conductive sheet is peeled from the main body of the thermally conductive sheet. The tack force of the surface of the heat conductive sheet main body (the tack force of the heat conductive sheet main body sandwiched between the release films) and the surface of the heat conductive sheet produced without being sandwiched between the release films and left for 7 days. When the tack force of the heat conductive sheet (the tack force of the heat conductive sheet not sandwiched between the release films) is compared with the tack force of the former, it means that the tack force of the former is large. The tack force can be measured by the method described in Examples below.

FIG. 1 is a cross-sectional view showing an example of a supply form of a heat conductive sheet according to the present technology. For example, as shown in FIG. 1, a thermally conductive sheet supply form 1 includes a thermally conductive sheet main body 3 sandwiched between release films 2 . That is, the supply form 1 of the heat conductive sheet is, for example, a laminate including the release film 2A, the heat conductive sheet main body 3, and the release film 2B in this order. In other words, in the supply mode 1 of the heat conductive sheet, the release films 2 are provided on both sides of one heat conductive sheet main body 3 .

Examples of the release film 2 include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyolefin, polymethylpentene, and glassine paper. The thickness of the release film 2 is not particularly limited and can be appropriately selected according to the purpose, and can be, for example, 5 to 200 μm. In addition, the thinner the release film 2 is, the better the conformability to the heat conductive sheet body 3 is, and the more effectively the heat conductive sheet body 3 can exhibit the tack force. For example, from the viewpoint of more effectively expressing the tack force of the heat conductive sheet main body 3, the release film 2 is preferably a thin PET film. The release film 2A and the release film 2B may be made of the same material or may be made of different materials. Moreover, the thickness of the release film 2A and the release film 2B may be the same or may be different.

The thickness of the heat conductive sheet main body 3 is not particularly limited, and can be appropriately selected according to the purpose. For example, the thickness of the heat conductive sheet main body 3 can be 0.05 mm or more, and can be 0.1 mm or more. Moreover, the upper limit of the thickness of the heat conductive sheet body 3 may be 5 mm or less, may be 4 mm or less, or may be 3 mm or less. The thickness of the heat-conducting sheet main body 3 is preferably 0.1 to 4 mm from the viewpoint of handleability. The thickness of the heat conductive sheet body 3 can be obtained, for example, by measuring the thickness of the heat conductive sheet body 3 at arbitrary five points and calculating the arithmetic average value thereof.

It is preferable that the heat conductive sheet main body 3 has a smaller specific gravity from the viewpoint of reducing the weight of the electronic component. For example, the heat conductive sheet main body 3 may have a specific gravity of 2.7 or less, 2.6 or less, 2.5 or less, or 2.4 or less. , 2.3 or less. Moreover, the heat conductive sheet body 3 may have a specific gravity of 2.0 or more, 2.1 or more, or 2.2 or more. The specific gravity of the heat conductive sheet main body 3 can be measured by the method described in Examples below.

FIG. 2 is a cross-sectional view showing an example of a heat conductive sheet main body that constitutes a supply form of the heat conductive sheet. The heat conductive sheet main body 3 includes a binder resin 4 and a heat conductive material 5 having shape anisotropy. Oriented. Moreover, the thermally conductive sheet body 3 may further include a thermally conductive material 6 other than the thermally conductive material 5 having shape anisotropy. Specific examples of the constituent elements of the heat conductive sheet main body 3 will be described below.

<Binder resin>
The binder resin 4 is for holding the heat conductive material 5 having shape anisotropy and another heat conductive material 6 in the heat conductive sheet main body 3 . The binder resin 4 is selected according to characteristics such as mechanical strength, heat resistance, and electrical properties required for the heat conductive sheet main body 3 . The binder resin 4 can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins.

Examples of thermoplastic resins include polyethylene, polypropylene, ethylene-α-olefin copolymers such as ethylene-propylene copolymers, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymers, Fluorinated polymers such as polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer Polymer (ABS) resin, polyphenylene-ether copolymer (PPE) resin, modified PPE resin, aliphatic polyamides, aromatic polyamides, polyimide, polyamideimide, polymethacrylic acid, polymethacrylic acid such as polymethacrylic acid methyl ester acid esters, polyacrylic acids, polycarbonates, polyphenylene sulfides, polysulfones, polyethersulfones, polyethernitrile, polyetherketones, polyketones, liquid crystal polymers, silicone resins, ionomers and the like.

Thermoplastic elastomers include styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers. , polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and the like.

Thermosetting resins include crosslinked rubbers, epoxy resins, phenol resins, polyimide resins, unsaturated polyester resins, diallyl phthalate resins, and the like. Specific examples of crosslinked rubber include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, and silicone rubber.

As the binder resin 4, for example, a silicone resin is preferable in consideration of the adhesion between the heat generating surface of the electronic component and the heat sink surface. As the silicone resin, for example, a two-component addition reaction type silicone resin composed of a silicone having an alkenyl group as a main component, a main agent containing a curing catalyst, and a curing agent having a hydrosilyl group (Si—H group). can be used. As the alkenyl group-containing silicone, for example, a vinyl group-containing polyorganosiloxane can be used. The curing catalyst is a catalyst for promoting the addition reaction between the alkenyl group in the alkenyl group-containing silicone and the hydrosilyl group in the hydrosilyl group-containing curing agent. As the curing catalyst, well-known catalysts used for hydrosilylation reaction can be used. For example, platinum group curing catalysts, such as platinum group metals such as platinum, rhodium and palladium, and platinum chloride can be used. As the curing agent having hydrosilyl groups, for example, polyorganosiloxane having hydrosilyl groups can be used. The binder resin 4 may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the binder resin 4 in the heat conductive sheet main body 3 is not particularly limited, and can be appropriately selected according to the purpose. For example, the content of the binder resin 4 in the heat conductive sheet body 3 may be 20% by volume or more, may be 25% by volume or more, or may be 30% by volume, from the viewpoint of the flexibility of the heat conductive sheet body 3. It may be vol % or more, and may be 33 vol % or more. In addition, the content of the binder resin 4 in the heat conductive sheet body 3 can be 70% by volume or less from the viewpoint of the flexibility of the heat conductive sheet body 3, and may be 60% by volume or less, or 50% by volume. It may be vol% or less, 40 vol% or less, or 37 vol% or less. The content of the binder resin 4 in the heat conductive sheet body 3 is preferably 25 to 60% by volume, and can be 30 to 40% by volume, for example, from the viewpoint of the flexibility of the heat conductive sheet body 3. , 33 to 37% by volume.

<Thermal conductive material having shape anisotropy>
The thermally conductive sheet main body 3 includes a thermally conductive material 5 having shape anisotropy. Shape anisotropy means that the shape is not constant in each direction, such as a sphere, or nearly constant in each direction, such as a cube or octahedron. It means that the shape differs depending on the direction, such as being longer or shorter than the other. Shape anisotropy includes, for example, scale-like and fibrous shapes. Here, the scaly thermally conductive material is a thermally conductive material having a long axis, a short axis, and a thickness, has a high aspect ratio (long axis/thickness), and is isotropic in the plane direction including the long axis. It has a good thermal conductivity. The short axis is a direction that intersects the long axis at approximately the center of the particles of the scale-like heat conductive material in a plane containing the long axis of the scale-like heat conductive material, and is the direction that intersects the long axis of the scale-like heat conductive material. Refers to the length of the short part. The thickness is an average value obtained by measuring ten thicknesses of the surface including the long axis of the scale-like thermally conductive material.

As the material of the thermally conductive material 5 having shape anisotropy, for example, boron nitride (BN), mica, alumina, aluminum nitride, silicon carbide, silica, zinc oxide, molybdenum disulfide, etc. can be used. Specific examples of the thermally conductive material 5 having shape anisotropy include scaly boron nitride and carbon fiber. The thermally conductive material 5 having shape anisotropy may be used singly or in combination of two or more.

FIG. 3 is a perspective view schematically showing scale-like boron nitride 5A having a hexagonal crystal shape, which is an example of a thermally conductive material having shape anisotropy. In FIG. 3, a represents the long axis of the scale-like boron nitride 5A, b represents the thickness of the scale-like boron nitride 5A, and c represents the short axis of the scale-like boron nitride 5A. As the heat conductive material 5 having shape anisotropy, from the viewpoint of the heat conductivity of the heat conductive sheet main body 3, it is possible to use scale-like boron nitride 5A having a hexagonal crystal shape as shown in FIG. preferable.

The average particle size (D50) of the thermally conductive material 5 having shape anisotropy is not particularly limited, and can be appropriately selected according to the purpose. For example, the average particle size of the thermally conductive material 5 having shape anisotropy may be 10 μm or more, may be 20 μm or more, may be 30 μm or more, or may be 35 μm or more. The upper limit of the average particle size of the thermally conductive material 5 having shape anisotropy may be 150 μm or less, may be 100 μm or less, may be 90 μm or less, or may be 80 μm or less. 70 μm or less, 50 μm or less, or 45 μm or less. From the viewpoint of the thermal conductivity of the heat conductive sheet main body 3, the average particle size of the heat conductive material 5 having shape anisotropy is preferably 20 to 100 μm. The aspect ratio of the thermally conductive material 5 having shape anisotropy is not particularly limited, and can be appropriately selected according to the purpose. For example, the aspect ratio of the thermally conductive material 5 having shape anisotropy can be in the range of 10-100. The average value of the ratio of the long axis to the short axis (major axis/minor axis) of the heat conductive material 5 having shape anisotropy can be, for example, in the range of 0.5 to 10, and 1 to 5. It can be a range, it can be a range of 1-3.

The content of the heat conductive material 5 having shape anisotropy in the heat conductive sheet main body 3 is not particularly limited, and can be appropriately selected according to the purpose. For example, the content of the heat conductive material 5 having shape anisotropy in the heat conductive sheet body 3 can be 15% by volume or more, and 20% by volume from the viewpoint of the thermal conductivity of the heat conductive sheet body 3. or more, or 23% by volume or more. In addition, the upper limit of the content of the thermally conductive material 5 having shape anisotropy in the thermally conductive sheet body 3 can be, for example, 45% by volume or less from the viewpoint of the flexibility of the thermally conductive sheet body 3. , 40% by volume or less, 35% by volume or less, or 30% by volume or less. From the viewpoint of the thermal conductivity of the heat conductive sheet body 3, the content of the heat conductive material 5 having shape anisotropy in the heat conductive sheet body 3 is preferably 20 to 35% by volume, and 20 to 30% by volume. %, more preferably 23 to 27% by volume.

<Other thermal conductive materials>
The other thermally conductive material 6 is a thermally conductive material other than the thermally conductive material 5 having shape anisotropy described above. That is, the other thermally conductive material 6 is a thermally conductive material that does not have shape anisotropy. The shape of the other thermally conductive material 6 may be, for example, spherical, powdery, or the like. The material of the other thermally conductive material 6 is not particularly limited, and may be the same as or different from the thermally conductive material 5 having shape anisotropy, for example. From the viewpoint of ensuring the insulation of the heat conductive sheet main body 3, other heat conductive materials 6 may be made of, for example, aluminum nitride, aluminum oxide (alumina, sapphire), zinc oxide, aluminum hydroxide, or the like. can. Other thermally conductive materials 6 may be used singly or in combination of two or more.

In particular, from the viewpoint of the thermal conductivity of the heat conductive sheet body 3, the other heat conductive material 6 is a combination of aluminum nitride particles and alumina particles, or a combination of aluminum nitride particles, alumina particles, zinc oxide, and aluminum hydroxide. is preferably used in combination. The average particle size (D50) of the aluminum nitride particles may be, for example, 1-5 μm, may be 1-3 μm, or may be 1-2 μm. Further, the average particle diameter (D50) of the alumina particles may be, for example, 0.1 to 10 μm, may be 0.1 to 8 μm, may be 0.1 to 7 μm, or may be 0.1 to 8 μm. It may be 1-2 μm. The average particle size (D50) of the zinc oxide particles can be, for example, 0.1 to 5 μm, may be 0.5 to 3 μm, or may be 0.5 to 2 μm. The average particle diameter (D50) of the aluminum hydroxide particles can be, for example, 1 to 10 μm, may be 2 to 9 μm, or may be 6 to 8 μm.

The content of the other thermally conductive material 6 in the thermally conductive sheet main body 3 is not particularly limited, and can be appropriately selected according to the purpose. The content of the other thermally conductive material 6 in the thermally conductive sheet body 3 can be 10% by volume or more, and may be 15% by volume or more, from the viewpoint of the thermal conductivity of the thermally conductive sheet body 3. , 20% by volume or more, 25% by volume or more, 30% by volume or more, or 35% by volume or more. In addition, the content of the other thermally conductive material 6 in the thermally conductive sheet body 3 can be 50% by volume or less from the viewpoint of the flexibility of the thermally conductive sheet body 3, and even if it is 45% by volume or less. It may be 40% by volume or less.

When aluminum nitride particles and alumina particles are used together as another thermally conductive material 6, the content of alumina particles in the thermally conductive sheet main body 3 is preferably 10 to 25% by volume, and the content of aluminum nitride particles is preferably 10 to 25% by volume. Further, when aluminum nitride particles, alumina particles, zinc oxide particles, and aluminum hydroxide particles are used together as the other thermally conductive material 6, the content of the alumina particles in the thermally conductive sheet main body 3 is 10 to 25% by volume. The content of aluminum nitride particles is preferably 10 to 25% by volume, the content of zinc oxide particles is preferably 0.1 to 3% by volume, and the content of aluminum hydroxide particles is preferably is preferably 0.1 to 3% by volume.

The heat-conducting sheet main body 3 may further contain components other than the components described above within a range that does not impair the effects of the present technology. Examples of other components include silane coupling agents (coupling agents), dispersants, curing accelerators, retarders, tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants, and the like. be done. For example, the heat conductive sheet body 3 further improves the dispersibility of the heat conductive material 5 having shape anisotropy and the other heat conductive material 6, and from the viewpoint of further improving the flexibility of the heat conductive sheet body 3, A thermally conductive material 5 having shape anisotropy treated with a silane coupling agent and/or another thermally conductive material 6 treated with a silane coupling agent may be used.

Next, a method for manufacturing the supply form 1 of the heat conductive sheet will be described. The manufacturing method of supply form 1 of the thermally conductive sheet includes a step of preparing a thermally conductive composition (hereinafter also referred to as step A) and a step of forming a molded block from the thermally conductive composition (hereinafter also referred to as step B). A step of slicing the molded block into sheets to obtain a heat conductive sheet (hereinafter also referred to as step C), and a step of arranging the surface of the heat conductive sheet between release films (hereinafter also referred to as step D) and

In step A, for example, a thermally conductive composition containing a binder resin 4, a thermally conductive material 5 having shape anisotropy, and another thermally conductive material 6 is prepared. The thermally conductive composition comprises binder resin 4, thermally conductive material 5 having shape anisotropy, other thermally conductive material 6, and, if necessary, various additives and volatile solvents by known methods. You may mix more uniformly. As one aspect of step A, a thermally conductive composition is prepared by dispersing a thermally conductive material 5 having shape anisotropy and another thermally conductive material 6 in a binder resin 4 .

In step B, the thermally conductive composition prepared in step A is formed into a molded block. Examples of methods for forming the molded block include an extrusion molding method and a mold molding method. The extrusion molding method and the mold molding method are not particularly limited, and various known extrusion molding methods and mold molding methods can be selected depending on the viscosity of the heat conductive composition and the properties required for the heat conductive sheet main body 3. It can be adopted as appropriate.

For example, when the thermally conductive composition is extruded from a die in the extrusion molding method, or when the thermally conductive composition is pressed into the mold in the mold molding method, the binder resin 4 flows and forms along the flow direction. An anisotropic thermal conductive material 5 is oriented.

The size and shape of the molded block can be determined according to the required size of the heat conductive sheet main body 3 . For example, a rectangular parallelepiped having a cross-sectional length of 0.5 to 15 cm and a width of 0.5 to 15 cm can be used. The length of the rectangular parallelepiped may be determined as required. In the extrusion molding method, it is easy to form a columnar molded block in which the long axis of the heat conductive material 5 having shape anisotropy is oriented in the extrusion direction and which is made of a cured product of the heat conductive composition.

In step C, the molded block is sliced into sheets to obtain heat conductive sheets. The thermally conductive material 5 having shape anisotropy is exposed on the surface (sliced surface) of the sheet obtained by slicing. The slicing method is not particularly limited, and can be appropriately selected from known slicing devices (preferably an ultrasonic cutter) according to the size and mechanical strength of the compact block. When the molding method is extrusion molding, the slicing direction of the molded block is 60 to 120 with respect to the extrusion direction, because the thermally conductive material 5 having shape anisotropy is oriented in the extrusion direction. degrees, more preferably in a direction of 70-100 degrees, and even more preferably in a direction of 90 degrees (perpendicular). When a columnar molded block is formed by an extrusion molding method in step B, in step C, the molded block is preferably sliced in a direction substantially perpendicular to the length direction.

In step D, by placing the surface of the heat conductive sheet between the release films 2, the supply form 1 of the heat conductive sheet as shown in FIG. A laminated body provided with and in this order is obtained.

Specifically, in step D, for example, the heat conductive sheet is sandwiched between the release films 2A and 2B, so that the binder resin 4 forming the heat conductive sheet body 3 spreads over the surface of the heat conductive sheet body 3 (heat conductive sheet body 3 and the release film 2), and the heat conductive sheet main body 3 comes to have tackiness. The binder resin 4 that seeps out onto the surface of the heat conductive sheet main body 3 may be in an uncured state or in a state in which curing has progressed by several percent.

In step D, from the viewpoint of more effectively expressing the tackiness of the heat conductive sheet main body 3, it is preferable to leave the surface of the heat conductive sheet to stand between the release films 2 for a predetermined period of time. The leaving time is not particularly limited, but can be, for example, 1 day or more, 2 days or more, 3 days or more, 4 days or more, or 5 days or more. , 6 days or more, or 7 days or more.

As described above, in the present manufacturing method, even if the supply form 1 of the thermally conductive sheet in which the surface of the thermally conductive sheet is arranged between the release films 2 is left for a predetermined time, the separation film 2 from the supply form 1 of the thermally conductive sheet is Since the surface of the heat conductive sheet main body 3 immediately after peeling has tackiness, the degree of freedom in the manufacturing process is large.

In addition, the manufacturing method of the supply form 1 of the heat conductive sheet is not limited to the above-described example, and may further include a step of pressing the sliced surface between the steps C and D, for example. By having such a step, the surface of the thermally conductive sheet obtained in step C is made smoother, and the adhesion between the other members and the thermally conductive sheet can be further improved. Alternatively, in the manufacturing method of supply form 1 of the heat conductive sheet, for example, after the surface of the heat conductive sheet is placed between the release films 2 in step D, the heat conductive sheet main body 3 sandwiched between the release films 2 is pressed. You may have a process. When the heat conductive sheet body 3 sandwiched between the release films 2 is pressed, the heat conductive sheet body 3 sandwiched between the release films 2 is pressed after pressing from the viewpoint of more effectively expressing the tackiness of the heat conductive sheet body 3. is preferably left for a predetermined period of time. As a method of pressing, a pair of press apparatuses comprising a flat plate and a press head having a flat surface can be used. Moreover, you may press with a pinch roll. The pressure during pressing may be, for example, in the range of 0.1 to 100 MPa, may be in the range of 0.1 to 1 MPa, or may be in the range of 0.1 to 0.5 MPa. . Press times can range, for example, from 10 seconds to 5 minutes, and may range from 30 seconds to 3 minutes. In order to further enhance the effect of pressing and shorten the pressing time, it is preferable to perform pressing at a temperature equal to or higher than the glass transition temperature (Tg) of the binder resin 4 . For example, the pressing temperature can be 0-180°C, can be in the temperature range of room temperature (eg, 25°C) to 100°C, or can be 30-100°C.

Next, a method of using the supply form 1 of the heat conductive sheet will be described. First, the release film 2 is peeled off from the supply form 1 of the heat conductive sheet. In this way, when the release film 2 is peeled off from the supply form 1 of the thermally conductive sheet, some of the components of the thermally conductive sheet main body 3 (the binder resin 4, the thermally conductive material 5 having shape anisotropy, and other thermally conductive materials 6) is transferred to the release film 2. As described above, the surface of the heat conductive sheet main body 3 immediately after peeling off the release film 2 from the heat conductive sheet supply form 1 has tackiness, so that the heat conductive sheet main body 3 can be prevented from being displaced during mounting.

[Second embodiment]
A second embodiment of the present technology is, for example, as shown in FIGS. is oriented in the thickness direction B of the heat conductive sheet body 3A, and both surfaces of the heat conductive sheet body 3A have tackiness. In other words, in the thermally conductive sheet body 3A, the surface direction of the scale-like boron nitride 5A (for example, the major axis a of the boron nitride 5A) may be oriented in the thickness direction B of the thermally conductive sheet body 3A. In this way, since the heat conductive sheet body 3A has tackiness on both sides, it is possible to suppress the positional deviation during mounting of the heat conductive sheet body 3A. In the second embodiment, it is assumed that both sides of the heat conductive sheet body 3A have tackiness, but the present invention is not limited to this example, and only one side of the heat conductive sheet body 3A has tackiness. may be

The heat conductive sheet main body 3A is the heat conductive sheet except that the heat conductive composition containing the binder resin 4 and the scale-like boron nitride 5A is used in the step A of the manufacturing method of the heat conductive sheet supply form 1 described above. It can be produced by the same method as the production method of the supply form 1 of . That is, the heat conductive sheet main body 3A includes a step A1 of preparing a heat conductive composition containing a binder resin 4 and scale-like boron nitride 5A, a step B1 of forming a molded block from the heat conductive composition, and a molding It can be obtained by a manufacturing method comprising a step C1 of slicing a body block into sheets to obtain a thermally conductive sheet, and a step D1 of arranging the surface of the thermally conductive sheet between the release films 7 . Thus, the heat conductive sheet main body 3A is sandwiched between the release films 7. As shown in FIG.

When the release film 7 is peeled off from the heat conductive sheet main body 3A sandwiched between the release films 7, part of the components of the heat conductive sheet main body 3A (at least one of the binder resin 4 and the scale-like boron nitride 5A) is removed from the release film 7. transfer to. This means that both surfaces of the heat conductive sheet main body 3A have tackiness.

Immediately after peeling off the release film 7, the thermally conductive sheet body 3A was pushed by 50 μm at 2 mm/sec using a probe with a diameter of 5.1 mm, and the surface tack force when peeled off at 10 mm/sec. It is preferably 20 gf or more, more preferably 75 gf or more, and even more preferably 80 gf or more.

A preferred range of the specific gravity of the heat conductive sheet body 3A is the same as that of the heat conductive sheet body 3 described above.

<Electronic equipment>
The heat conductive sheet main body 3 from which the release film 2 is peeled off from the heat conductive sheet supply form 1 described above is arranged, for example, between a heat generating body and a radiator, so that the heat generated by the heat generating body is transferred to the heat radiator. It can be an electronic device (thermal device) with a structure arranged between them for escape. The electronic device has at least a heating element, a radiator, and a thermally conductive sheet main body 3, and may further have other members as necessary. In the following description, the heat conductive sheet main body 3 shall also include the heat conductive sheet main body 3A.

The heating element is not particularly limited, and includes, for example, CPU (Central Processing Unit), GPU (Graphics Processing Unit), DRAM (Dynamic Random Access Memory), integrated circuit elements such as flash memory, transistors, resistors, electric circuits, etc. and electronic components that generate heat in. The heating element also includes components for receiving optical signals, such as optical transceivers in communication equipment.

The radiator is not particularly limited, and examples thereof include heat sinks, heat spreaders, and the like, which are used in combination with integrated circuit elements, transistors, optical transceiver housings, and the like. As the radiator, in addition to the heat spreader and the heat sink, any material can be used as long as it conducts the heat generated from the heat source and dissipates it to the outside. A heat pipe, a metal cover, a housing, and the like can be mentioned.

FIG. 5 is a cross-sectional view showing an example of a semiconductor device to which the heat conductive sheet body according to the present technology is applied. For example, as shown in FIG. 5, the heat conductive sheet main body 3 is mounted on a semiconductor device 50 built in various electronic devices, and sandwiched between a heat generator and a radiator. A semiconductor device 50 shown in FIG. 5 includes an electronic component 51 , a heat spreader 52 , and a heat conductive sheet body 3 . The heat conductive sheet main body 3 is sandwiched between the heat spreader 52 and the heat sink 53 , thereby forming a heat dissipation member for dissipating the heat of the electronic component 51 together with the heat spreader 52 . The mounting location of the heat conductive sheet main body 3 is not limited to between the heat spreader 52 and the electronic component 51 or between the heat spreader 52 and the heat sink 53, but can be appropriately selected according to the configuration of the electronic device or semiconductor device.

Examples of the present technology will be described below. The present technology is not limited to these examples.

<Example 1>
In Example 1, 33% by volume of silicone resin, 27% by volume of scaly boron nitride having a hexagonal crystal shape (D50 is 40 μm), 20% by volume of aluminum nitride (D50 is 1.2 μm), and alumina A resin composition for forming a heat conductive sheet was prepared by uniformly mixing 19% by volume of particles (D50 of 1 μm) and 1% by volume of a silane coupling agent. By extrusion molding, the resin composition for forming the heat conductive sheet is poured into a mold (opening: 50 mm × 50 mm) having a rectangular parallelepiped internal space, and heated in an oven at 60 ° C. for 4 hours to form a molded block. formed. A release PET film was attached to the inner surface of the mold so that the release-treated surface faced the inside. By slicing the resulting molded block into a sheet having a thickness of 1 mm with a slicer, a thermally conductive sheet in which scale-like boron nitride was oriented in the thickness direction of the sheet was obtained. The obtained thermally conductive sheet was sandwiched between release-treated PET films to obtain a supply form of the thermally conductive sheet. This supply form of the heat conductive sheet was left for one week (7 days).

<Example 2>
In Example 2, 37% by volume of silicone resin, 23% by volume of scaly boron nitride (D50 is 40 μm) having a hexagonal crystal shape, 20% by volume of aluminum nitride (D50 is 1.5 μm), and alumina A resin composition for forming a heat conductive sheet is prepared by uniformly mixing 17% by volume of particles (D50 of 1 μm), 1% by volume of aluminum hydroxide (8 μm of D50), and 1% by volume of a silane coupling agent. A heat conductive sheet was obtained in the same manner as in Example 1 except for the preparation. The obtained thermally conductive sheet was sandwiched between release-treated PET films to obtain a supply form of the thermally conductive sheet. This supply form of the heat conductive sheet was left for one week (7 days).

<Comparative Example 1>
In Comparative Example 1, a thermally conductive sheet obtained in the same manner as in Example 1 was allowed to stand for 7 days without being sandwiched between release-treated PET films.

<Comparative Example 2>
In Comparative Example 2, 37% by volume of silicone resin, 23% by volume of scaly boron nitride (D50 is 40 μm) having a hexagonal crystal shape, 20% by volume of aluminum nitride (D50 is 1.5 μm), and alumina A resin composition for forming a heat conductive sheet was prepared by uniformly mixing 19% by volume of particles (D50 of 1 μm) and 1% by volume of a silane coupling agent. A heat conductive sheet was obtained in the same manner as in Example 1 using this resin composition for forming a heat conductive sheet. It was allowed to stand for 7 days without being sandwiched between release-treated PET films.

<Thermal conductivity>
Thermal conductivity in the thickness direction of the thermally conductive sheets obtained in Comparative Examples 1 and 2 ( W/m·K) were measured respectively. Specifically, using a thermal resistance measuring device conforming to ASTM-D5470, a load of 1 kgf/cm ² was applied, and the thermal conductivity of the heat conductive sheet main body or the heat conductive sheet immediately after production and after leaving for 7 days after production was measured. Table 1 shows the results.

<Specific gravity>
Regarding the heat conductive sheet bodies obtained in Examples 1 and 2 and the heat conductive sheets obtained in Comparative Examples 1 and 2, the volume obtained from the length and width and the thickness and the heat conductive sheet body or heat conductive sheet The specific gravity was obtained by measuring the weight. Table 1 shows the results.

<Thermal conductive sheet after slicing>
In the column of "heat conductive sheet after slicing" in Table 1, "sandwiched between PET" means when the obtained heat conductive sheet is sandwiched between release-treated PET films (Examples 1 and 2). represents In addition, "not sandwiched between PET" refers to the case where the obtained thermally conductive sheet was not sandwiched between release-treated PET films (Comparative Examples 1 and 2).

<Fixation to aluminum plate>
FIG. 6 is a diagram for explaining a method of evaluating whether or not the aluminum plate slides down when the heat conductive sheet main body is placed on the aluminum plate and shifted by 90°. For example, in Examples 1 and 2, as shown in FIG. 6(A), after placing the heat conductive sheet body 3 (3A) on the horizontally placed aluminum plate 8, as shown in FIG. 6(B), Second, it was evaluated whether or not the aluminum plate 8 slipped down when the aluminum plate 8 was tilted 90° while holding the heat conductive sheet main body 3 (3A). Table 1 shows the results. In Table 1, "fixed just by placing" means that the aluminum plate 8 did not slip down, and "not fixed" means that the aluminum plate 8 slipped down. In Examples 1 and 2, a heat conductive sheet main body was used in which the peel-treated PET film was peeled off after the obtained heat conductive sheet was left in the supply form for 7 days. In Comparative Examples 1 and 2, the obtained thermally conductive sheet was left for 7 days without being sandwiched between release-treated PET films.

<Transferring after peeling off the sheet>
The supply form of the thermally conductive sheet immediately after obtained in Examples 1 and 2 was pressed at 0.5 MPa for 30 seconds, and when the peeled PET film was peeled off from the supply form of this thermally conductive sheet, this PET It was visually confirmed whether marks (white) of the heat conductive sheet main body adhered to the film. Further, in Comparative Examples 1 and 2, the heat conductive sheet immediately after being obtained was sandwiched between release-treated PET films and pressed at 0.5 MPa for 30 seconds, and then when the release-treated PET films were peeled off, It was visually confirmed whether or not marks (white) of the thermally conductive sheet adhered to the PET film. Table 1 shows the results.

<Tack force immediately after sheeting>
Immediately after the supply form of the thermally conductive sheet obtained in Examples 1 and 2 was pressed at 0.5 MPa for 30 seconds, and the peeled PET film was peeled off from the supply form of the thermally conductive sheet (within 3 minutes). 2, the tack force (gf) of the surface of the thermally conductive sheet body when the thermally conductive sheet body was pushed in at 2 mm/sec by 50 µm using a probe with a diameter of 5.1 mm and pulled out at 10 mm/sec was determined. In addition, immediately after the thermally conductive sheets obtained in Comparative Examples 1 and 2 were sandwiched between release-treated PET films and pressed at 0.5 MPa for 30 seconds, immediately after the release-treated PET films were peeled off ( Within 3 minutes), the thermal conductive sheet was pushed by 50 μm at 2 mm/sec using a probe with a diameter of 5.1 mm, and the tack force (gf) of the thermal conductive sheet surface when peeled off at 10 mm/sec was determined. Table 1 shows the results.

<Tack power after standing for 7 days>
The supply form of the thermally conductive sheet immediately after obtained in Examples 1 and 2 was pressed at 0.5 MPa for 30 seconds and left for 7 days. Immediately after (within 3 minutes), the thermal conductive sheet body was pushed by 50 μm at 2 mm/sec using a probe with a diameter of 5.1 mm, and the surface tack force (gf) of the thermal conductive sheet body when pulled out at 10 mm/sec was determined. . In Comparative Examples 1 and 2, the heat conductive sheet immediately after being obtained was sandwiched between release-treated PET films and pressed at 0.5 MPa for 30 seconds, then the release-treated PET film was peeled off and left for 7 days. After that, the tack force (gf) of the surface of the heat conductive sheet was obtained in the same manner as in Examples 1 and 2. Table 1 shows the results.

In Examples 1 and 2, since the heat conductive sheet sandwiched between the release films was supplied, it was found that the surface of the heat conductive sheet main body immediately after peeling the release film from the heat conductive sheet had tackiness. rice field. In addition, in the supply form of the heat conductive sheet in Examples 1 and 2, the surface of the heat conductive sheet main body immediately after peeling the release film from the heat conductive sheet main body had tackiness. It turned out that it is fixed when the seat body is placed. From this, it was suggested that the supply form of the thermally conductive sheet in Examples 1 and 2 can suppress positional deviation during mounting of the thermally conductive sheet main body.

On the other hand, in Comparative Examples 1 and 2, since the thermally conductive sheets that were not sandwiched between the release films were used, the surfaces of the thermally conductive sheets did not have tackiness compared to the supply forms of the thermally conductive sheets of Examples 1 and 2. I found out. Moreover, it was found that the heat conductive sheets in Comparative Examples 1 and 2 were not fixed when the heat conductive sheets were placed on the aluminum plate. This suggests that it is difficult for the thermally conductive sheets in Comparative Examples 1 and 2 to suppress misalignment during mounting of the thermally conductive sheets.

1 supply form of thermally conductive sheet, 2 release film, 3, 3A thermally conductive sheet body, 4 binder resin, 5 thermally conductive material having shape anisotropy, 5A scaly boron nitride, a major axis, b thickness, c short axis, 6 other thermally conductive material, 7 release film, 8 aluminum plate, 50 semiconductor device, 51 electronic component, 52 heat spreader, 53 heat sink

Claims (22)

A supply form of a heat conductive sheet in which a heat conductive sheet body is sandwiched between release films,
A thermally conductive sheet is supplied in such a manner that the surface of the thermally conductive sheet main body immediately after peeling the release film from the thermally conductive sheet main body has tackiness. The supply form of the thermally conductive sheet according to claim 1, wherein the tack force of the thermally conductive sheet main body sandwiched between the release films is increased compared to the tack force of the thermally conductive sheet not sandwiched between the release films. . The heat conductive sheet body contains a binder resin and a heat conductive material having shape anisotropy,
3. The supply form of the thermally conductive sheet according to claim 1, wherein the major axis of the thermally conductive material having shape anisotropy is oriented in the thickness direction of the thermally conductive sheet body. 4. The supply form of the thermally conductive sheet according to claim 3, wherein the thermally conductive material having shape anisotropy is scaly boron nitride or carbon fiber. 5. The supply form of the thermally conductive sheet according to claim 1, wherein the tack force of the thermally conductive sheet body immediately after peeling off the release film is 80 gf or more according to the following measuring method.
Measurement method: Immediately after peeling off the release film from the heat conductive sheet body, a probe with a diameter of 5.1 mm is used to push the heat conductive sheet body 50 μm at 2 mm/sec and pull it out at 10 mm/sec. The heat conduction according to any one of claims 1 to 5, wherein when the release film is peeled from the heat conductive sheet body, a part of the components of the heat conductive sheet body is transferred to the release film. Form of sheet supply. The supply form of the thermally conductive sheet according to any one of claims 1 to 6, wherein the thermally conductive sheet main body further contains at least one of alumina, aluminum nitride, zinc oxide and aluminum hydroxide. The heat conductive sheet main body contains a binder resin,
The supply form of the heat conductive sheet according to any one of claims 1 to 7, wherein the binder resin is a silicone resin. The supply form of the thermally conductive sheet according to any one of claims 1 to 8, wherein the release films are provided on both sides of one thermally conductive sheet body. The supply form of the thermally conductive sheet according to any one of claims 1 to 8, wherein the release film is provided on both sides of a plurality of the thermally conductive sheet bodies arranged vertically and horizontally at predetermined intervals. A thermally conductive sheet main body obtained by peeling a release film from the supply form of the thermally conductive sheet according to any one of claims 1 to 10. An electronic device comprising the heat conductive sheet body according to claim 11 . A method for producing a heat conductive sheet in a supply form in which a heat conductive sheet body is sandwiched between release films,
preparing a thermally conductive composition comprising a binder resin and a thermally conductive material having shape anisotropy;
forming a molded block from the thermally conductive composition;
obtaining a thermally conductive sheet by slicing the molded block into sheets;
and disposing the surface of the heat conductive sheet between the release films. Containing a binder resin and scaly boron nitride,
The scale-like boron nitride is oriented in the thickness direction of the heat conductive sheet body,
A thermally conductive sheet body having tackiness on both sides of the thermally conductive sheet body. 15. The method according to claim 14, wherein the surface of the thermally conductive sheet body has a tack force of 80 gf or more when the thermally conductive sheet body is pushed by 50 μm at 2 mm/sec with a probe having a diameter of 5.1 mm and is peeled off at 10 mm/sec. Thermal conductive sheet body. A supply form of a thermally conductive sheet, wherein the thermally conductive sheet main body according to claim 14 or 15 is sandwiched between release films. A supply form of a thermally conductive sheet in which the thermally conductive sheet body according to any one of claims 14 to 16 is arranged between release films. When the release film is peeled off from the heat conductive sheet body, part of at least one of the binder resin and the scaly boron nitride constituting the heat conductive sheet body is transferred to the release film. 18. Supply form of the thermally conductive sheet according to Item 16 or 17. 16. The thermally conductive sheet body according to claim 14 or 15, further comprising at least one of alumina, aluminum nitride, zinc oxide, and aluminum hydroxide. The heat conductive sheet main body according to claim 14 or 15, wherein the binder resin is a silicone resin. An electronic device comprising the thermally conductive sheet main body according to claim 14 or 15 between a heating element and a radiator. A method for producing a heat conductive sheet in a supply form in which a heat conductive sheet body is sandwiched between release films,
preparing a thermally conductive composition comprising a binder resin and scaly boron nitride;
forming a molded block from the thermally conductive composition;
obtaining a thermally conductive sheet by slicing the molded block into sheets;
and disposing the surface of the heat conductive sheet between the release films.

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