JP7057845B1 - Supply form of heat conductive sheet and heat conductive sheet body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conductive sheet having a tack property on a surface. SOLUTION: In the heat conductive sheet supply form 1, the heat conductive sheet main body 3 is sandwiched between the release films 2, and the surface of the heat conductive sheet main body 3 immediately after the release film 2 is peeled from the heat conductive sheet main body 3 is formed. Has tackiness. [Selection diagram] Fig. 1

Description

The present technology relates to a supply form of a heat conductive sheet and a heat conductive sheet main body.

As the performance of electronic devices increases, the density and mounting of semiconductor devices are increasing. Along with this, it is important to more efficiently dissipate heat generated from the electronic components constituting the electronic device. For example, in a semiconductor device, electronic components are attached to heat sinks such as a heat dissipation fan and a heat dissipation plate via a heat conductive sheet in order to efficiently dissipate heat. As the heat conductive sheet, for example, a silicone resin containing (dispersed) a filler such as an inorganic filler is widely used. A heat radiating member such as this heat conductive sheet is required to further improve the heat conductivity. For example, for the purpose of high thermal conductivity of a heat conductive sheet, it has been studied to increase the filling rate of an inorganic filler blended in a matrix such as a binder resin. However, if the filling rate of the inorganic filler is increased, the flexibility of the heat conductive sheet is impaired and powder falling occurs, so that there is a limit to increasing the filling rate of the inorganic filler.

Examples of the inorganic filler include alumina, aluminum nitride, aluminum hydroxide and the like. Further, for the purpose of high thermal conductivity, the matrix may be filled with scaly particles such as boron nitride and graphite, carbon fibers and the like. This is due to the anisotropy of the thermal conductivity of the scaly particles and the like. For example, carbon fiber is known to have a thermal conductivity of about 600 to 1200 W / m · K in the fiber direction. Further, in the case of boron nitride, it may have 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 scaly particles is the same as the thickness direction of the sheet, which is the heat transfer direction, that is, the carbon fibers and scaly particles are oriented in the thickness direction of the sheet to generate heat. It can be expected that the conductivity will be dramatically improved.

Patent Document 1 describes a heat conductive sheet in which boron nitride is oriented in the thickness direction. In such a heat conductive sheet, for example, an anisotropic material can be oriented in the thickness direction of the heat conductive sheet by preparing a molded block from a resin composition for forming the heat conductive sheet and slicing it. However, when the heat conductive sheet is produced by slicing the molded block in this way, there is a problem that the surface of the heat conductive sheet has no tackiness. As described above, if the surface of the heat conductive sheet is not tacky, misalignment may occur when the heat conductive sheet is mounted.

International Publication WO2019 / 026745

This technique has been proposed in view of such conventional circumstances, and provides a heat conductive sheet having a tack property on the surface.

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

The heat conductive sheet body according to this technique contains a binder resin and scaly boron nitride, and the scaly boron nitride is oriented in the thickness direction of the conductive sheet body, and both sides of the heat conductive sheet body are tacky. Have.

According to this technique, it is possible to provide a heat conductive sheet having a tack property on the 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 constituting a supply form of the heat conductive sheet. FIG. 3 is a perspective view schematically showing scaly boron nitride having a hexagonal crystal shape, which is an example of a heat conductive material having shape anisotropy. FIG. 4 is a cross-sectional view showing an example of the 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 main body is applied. FIG. 6 is a diagram for explaining a method of evaluating whether or not the aluminum plate slides off when the heat conductive sheet main body is placed on the aluminum plate and shifted by 90 °.

In the present specification, the average particle size (D50) of the heat conductive material is a cumulative curve of the particle size values from the small particle size side of the particle size distribution when the entire particle size distribution of the heat conductive material is 100%. It means the particle size when the cumulative value becomes 50%. The particle size distribution (particle size distribution) in the present specification is obtained by the volume standard. As a method for measuring the particle size distribution, for example, a method using a laser diffraction type particle size distribution measuring machine can be mentioned.

[First Embodiment]
<Supply form of heat conductive sheet>
In the first embodiment of the present technology, the heat conductive sheet main body is sandwiched between the release film (the film subjected to the release treatment), and the heat conductive sheet main body immediately after the release film is peeled from the heat conductive sheet main body. It is a supply form of a heat conductive sheet having a tack property on the surface. As described above, in the supply form of the heat conductive sheet according to the present technology, since the surface of the heat conductive sheet main body immediately after the release film is peeled from the heat conductive sheet main body has tackiness, the position at the time of mounting the heat conductive sheet main body is obtained. The deviation can be suppressed.

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

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

Further, in the supply form of the heat conductive sheet, it is preferable that the tack force of the heat conductive sheet main body sandwiched between the release films is increased as compared with the tack force of the heat conductive sheet not sandwiched by the release film. For example, after preparing the supply form of the heat conductive sheet in which the heat conductive sheet main body is sandwiched between the release films and leaving it for 7 days, immediately after the release film of the supply form of the heat conductive sheet is peeled from the heat conductive sheet main body. The tack force on the surface of the heat conductive sheet body (tack force of the heat conductive sheet body sandwiched between the release films) and the surface of the sheet left for 7 days after the heat conductive sheet was prepared without being sandwiched by the release film. When compared with the tack force of (the tack force of the heat conductive sheet that is not sandwiched between the release films), it means that the tack force of the former is large. The tack force can be measured by the method described in Examples described later.

FIG. 1 is a cross-sectional view showing an example of a supply form of a heat conductive sheet according to the present technology. As shown in FIG. 1, for example, the heat conductive sheet supply form 1 includes a heat conductive sheet main body 3 sandwiched between the release films 2. That is, the heat conductive sheet supply form 1 is, for example, a laminated body 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 heat conductive sheet supply form 1, the release film 2 is 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, glassine paper and the like. The thickness of the release film 2 is not particularly limited and can be appropriately selected depending on the intended purpose, for example, 5 to 200 μm. Further, the thinner the release film 2, the better the followability to the heat conductive sheet main body 3, and the tack force of the heat conductive sheet main body 3 can be more effectively exhibited. 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 PET film having a thin thickness. The release film 2A and the release film 2B may be made of the same material or may be made of different materials. Further, the release film 2A and the release film 2B may have the same thickness or may have different thicknesses.

The thickness of the heat conductive sheet main body 3 is not particularly limited and can be appropriately selected depending on the intended purpose. For example, the thickness of the heat conductive sheet main body 3 can be 0.05 mm or more, or 0.1 mm or more. Further, the upper limit of the thickness of the heat conductive sheet main body 3 can be 5 mm or less, may be 4 mm or less, or may be 3 mm or less. From the viewpoint of handleability, the heat conductive sheet main body 3 preferably has a thickness of 0.1 to 4 mm. The thickness of the heat conductive sheet main body 3 can be obtained from, for example, the thickness of the heat conductive sheet main body 3 measured at arbitrary five points and the arithmetic mean value thereof.

From the viewpoint of reducing the weight of electronic components, the heat conductive sheet main body 3 preferably has a smaller specific gravity. 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. It may be 2.3 or less. Further, the heat conductive sheet main 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 described later.

FIG. 2 is a cross-sectional view showing an example of a heat conductive sheet main body constituting a supply form of the heat conductive sheet. The heat conductive sheet main body 3 contains a binder resin 4 and a heat conductive material 5 having shape anisotropy, and the major axis of the heat conductive material 5 having shape anisotropy is in the thickness direction B of the heat conductive sheet body 3. It is oriented. Further, the heat conductive sheet main body 3 may further contain a heat conductive material 6 other than the heat conductive material 5 having shape anisotropy. Hereinafter, specific examples of the components of the heat conductive sheet main body 3 will be described.

<Binder resin>
The binder resin 4 is for holding the heat conductive material 5 having shape anisotropy and the other heat conductive material 6 in the heat conductive sheet main body 3. The binder resin 4 is selected according to the 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 a thermoplastic resin, a thermoplastic elastomer, and a thermosetting resin.

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

Examples of the thermoplastic elastomer include a styrene-butadiene block copolymer or a hydrogenated product thereof, a styrene-isoprene block copolymer or a hydrogenated product thereof, a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and a vinyl chloride-based thermoplastic elastomer. , Polyester-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyamide-based thermoplastic elastomer and the like.

Examples of the thermosetting resin include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin and the like. Specific examples of the 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, and chlorinated polyethylene rubber. Examples thereof include 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 and the heat sink surface of the electronic component. The silicone resin is, for example, a two-component addition reaction type silicone resin containing 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 silicone having an alkenyl group, for example, a polyorganosiloxane having a vinyl group can be used. The curing catalyst is a catalyst for accelerating the addition reaction between the alkenyl group in the silicone having an alkenyl group and the hydrosilyl group in the curing agent having a hydrosilyl group. Examples of the curing catalyst include well-known catalysts as catalysts used in the hydrosilylation reaction, and for example, platinum group curing catalysts such as platinum group metal alone such as platinum, rhodium and palladium, platinum chloride and the like can be used. As the curing agent having a hydrosilyl group, for example, polyorganosiloxane having a hydrosilyl group can be used. The binder resin 4 may be used alone or in combination of two or more.

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

<Heat conductive material with shape anisotropy>
The heat conductive sheet main body 3 contains a heat conductive material 5 having shape anisotropy. Shape anisotropy means that the shape is not constant in each direction such as a sphere, or the shape is not close to constant in each direction such as a cube or an octahedron, and one axis is more than another axis. It means that the shape is different depending on the direction, such as long or short, and for example, it means a shape in which the lengths of the long axis and the short axis are different and the aspect ratio is not 1. The shape anisotropy includes, for example, scaly and fibrous shapes. Here, the scaly heat conductive material is a heat conductive material having a major axis, a minor axis, and a thickness, has a high aspect ratio (major axis / thickness), and is isotropic in the plane direction including the major axis. It has a typical thermal conductivity. The short axis is the direction that intersects the long axis at the substantially central portion of the particles of the scaly heat conductive material on the surface including the long axis of the scaly heat conductive material, and is the most of the scaly heat conductive material. The length of the short part. The thickness means a value obtained by measuring and averaging the thicknesses of the surfaces including the long axis of the scaly heat conductive material at 10 points.

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

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

The average particle size (D50) of the heat conductive material 5 having shape anisotropy is not particularly limited and can be appropriately selected depending on the intended purpose. For example, the average particle size of the heat conductive material 5 having shape anisotropy can be 10 μm or more, may be 20 μm or more, may be 30 μm or more, or may be 35 μm or more. Further, the upper limit of the average particle size of the heat conductive material 5 having shape anisotropy can be 150 μm or less, may be 100 μm or less, may be 90 μm or less, or may be 80 μm or less. It may be 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 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 heat conductive material 5 having shape anisotropy is not particularly limited and can be appropriately selected depending on the intended purpose. For example, the aspect ratio of the heat conductive material 5 having shape anisotropy can be in the range of 10 to 100. The average value of the ratio (major axis / minor axis) between the major axis and the 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, or it can be a range of 1 to 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 depending on the intended purpose. For example, the content of the heat conductive material 5 having shape anisotropy in the heat conductive sheet main body 3 can be 15% by volume or more from the viewpoint of the thermal conductivity of the heat conductive sheet main body 3, and is 20% by volume. It may be more than 23% by volume or more. Further, the upper limit of the content of the heat conductive material 5 having shape anisotropy in the heat conductive sheet main body 3 can be, for example, 45% by volume or less from the viewpoint of the flexibility of the heat conductive sheet main 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, preferably 20 to 30% by volume. %, More preferably 23 to 27% by volume.

<Other heat conductive materials>
The other heat conductive material 6 is a heat conductive material other than the heat conductive material 5 having the above-mentioned shape anisotropy. That is, the other heat conductive material 6 is a heat conductive material having no shape anisotropy. Examples of the shape of the other heat conductive material 6 include a spherical shape and a powder shape. The material of the other heat conductive material 6 is not particularly limited, and may be, for example, the same as or different from the heat conductive material 5 having shape anisotropy. Further, from the viewpoint of ensuring the insulating property of the heat conductive sheet main body 3, as the material of the other heat conductive material 6, for example, aluminum nitride, aluminum oxide (alumina, sapphire), zinc oxide, aluminum hydroxide and the like may be used. can. The other heat conductive material 6 may be used alone or in combination of two or more.

In particular, the other heat conductive material 6 includes an embodiment in which aluminum nitride particles and alumina particles are used in combination, aluminum nitride particles, alumina particles, zinc oxide, and aluminum hydroxide in terms of the thermal conductivity of the heat conductive sheet body 3. Is preferable in combination with. The average particle size (D50) of the aluminum nitride particles can be, for example, 1 to 5 μm, may be 1 to 3 μm, or may be 1 to 2 μm. The average particle size (D50) of the alumina particles can be, for example, 0.1 to 10 μm, 0.1 to 8 μm, 0.1 to 7 μm, or 0. It may be 1 to 2 μm. The average particle size (D50) of the zinc oxide particles can be, for example, 0.1 to 5 μm, 0.5 to 3 μm, or 0.5 to 2 μm. The average particle size (D50) of the aluminum hydroxide particles can be, for example, 1 to 10 μm, 2 to 9 μm, or 6 to 8 μm.

The content of the other heat conductive material 6 in the heat conductive sheet main body 3 is not particularly limited and can be appropriately selected depending on the intended purpose. The content of the other heat conductive material 6 in the heat conductive sheet main body 3 can be 10% by volume or more, and may be 15% by volume or more, from the viewpoint of the heat conductivity of the heat conductive sheet main body 3. , 20% by volume or more, 25% by volume or more, 30% by volume or more, or 35% by volume or more. Further, the content of the other heat conductive material 6 in the heat conductive sheet main body 3 can be 50% by volume or less from the viewpoint of the flexibility of the heat conductive sheet main body 3, 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 in combination as the other heat conductive material 6, the content of the alumina particles in the heat conductive sheet main body 3 is preferably 10 to 25% by volume, and the content of the aluminum nitride particles. Is preferably 10 to 25% by volume. When aluminum nitride particles, alumina particles, zinc oxide particles, and aluminum hydroxide particles are used in combination as the other heat conductive material 6, the content of the alumina particles in the heat conductive sheet main body 3 is 10 to 25% by volume. The content of the aluminum nitride particles is preferably 10 to 25% by volume, the content of the zinc oxide particles is preferably 0.1 to 3% by volume, and the content of the aluminum hydroxide particles. Is preferably 0.1 to 3% by volume.

The heat conductive sheet main body 3 may further contain components other than the above-mentioned components as long as the effects of the present technique are not impaired. 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 has a viewpoint of further improving the dispersibility of the heat conductive material 5 having shape anisotropy and the other heat conductive material 6 and further improving the flexibility of the heat conductive sheet body 3. A heat conductive material 5 having shape anisotropy treated with a silane coupling agent and / or another heat conductive material 6 treated with a silane coupling agent may be used.

Next, a method for manufacturing the heat conductive sheet supply form 1 will be described. The method for producing the heat conductive sheet supply form 1 is a step of preparing a heat conductive composition (hereinafter, also referred to as step A) and a step of forming a molded body block from the heat conductive composition (hereinafter, also referred to as step B). A step of slicing the molded block into a sheet 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 the release films (hereinafter, also referred to as step D). And have.

In step A, for example, a heat conductive composition containing a binder resin 4, a heat conductive material 5 having shape anisotropy, and another heat conductive material 6 is prepared. As the heat conductive composition, in addition to the binder resin 4, the heat conductive material 5 having shape anisotropy, and the other heat conductive material 6, various additives and volatile solvents are used as required by known methods. May be mixed more evenly. As one aspect of the step A, a heat conductive material 5 having shape anisotropy and another heat conductive material 6 are dispersed in the binder resin 4 to prepare a heat conductive composition.

In step B, a molded block is formed from the heat conductive composition prepared in step A. Examples of the method for forming the molded body 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 among various known extrusion molding methods and mold molding methods, the viscosity of the heat conductive composition, the characteristics required for the heat conductive sheet main body 3, and the like can be obtained. It can be adopted as appropriate.

For example, in the extrusion molding method, when the heat conductive composition is extruded from a die, or in the mold forming method, when the heat conductive composition is press-fitted into a mold, the binder resin 4 flows and has a shape along the flow direction. The heat conductive material 5 having anisotropy is oriented.

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

In step C, the molded block is sliced into a sheet to obtain a heat conductive sheet. The heat 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 ultrasonic cutters) depending on the size and mechanical strength of the molded block. When the molding method is the extrusion molding method, the slice direction of the molded body block may be 60 to 120 with respect to the extrusion direction because the heat conductive material 5 having shape anisotropy may be oriented in the extrusion direction. The degree is preferable, the direction is more preferably 70 to 100 degrees, and the direction is more preferably 90 degrees (vertical). When a columnar molded body block is formed by an extrusion molding method in step B, it is preferable to slice in a direction substantially perpendicular to the length direction of the molded body block in step C.

In step D, by arranging the surface of the heat conductive sheet between the release films 2, the heat conductive sheet supply form 1 as shown in FIG. 1, that is, the release film 2A, the heat conductive sheet main body 3, and the release film 2B A laminated body having the above in this order can be obtained.

Specifically, in step D, for example, by sandwiching the heat conductive sheet between the release films 2A and 2B, the binder resin 4 constituting the heat conductive sheet main body 3 is formed on the surface of the heat conductive sheet main body 3 (heat conductive sheet main body 3). (Between the release film 2 and the release film 2), and the heat conductive sheet body 3 becomes tacky. The binder resin 4 that exudes to the surface of the heat conductive sheet main body 3 may be in an uncured state or may be in a state of being cured by several percent.

In step D, from the viewpoint of more effectively exhibiting the tackiness of the heat conductive sheet main body 3, it is preferable to place the surface of the heat conductive sheet between the release films 2 and then leave it for a predetermined time. The leaving time is not particularly limited, but may be, for example, one day or more, may be two days or more, may be three days or more, may be four days or more, and may be five days or more. It may be 6 days or more, or 7 days or more.

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

The method for producing the heat conductive sheet supply form 1 is not limited to the above-mentioned example, and may further include, for example, a step of pressing the sliced surface between the step C and the step D. By having such a step, the surface of the heat conductive sheet obtained in the step C is further smoothed, and the adhesion between the other member and the heat conductive sheet can be further improved. Alternatively, in the method of manufacturing the heat conductive sheet supply form 1, for example, after arranging the surface of the heat conductive sheet between the release films 2 in step D, the heat conductive sheet main body 3 sandwiched between the release films 2 is pressed. It may have a process. When the heat conductive sheet main body 3 sandwiched between the release films 2 is pressed, the heat conductive sheet main body 3 sandwiched between the release films 2 after pressing is used from the viewpoint of more effectively expressing the tackiness of the heat conductive sheet main body 3. Is preferably left for a predetermined time. As a pressing method, a pair of pressing devices including a flat plate and a pressing head having a flat surface can be used. Alternatively, it may be pressed with a pinch roll. The pressure at the time of 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. .. The press time can be, for example, in the range of 10 seconds to 5 minutes, and may be in the range of 30 seconds to 3 minutes. In order to further enhance the effect of pressing and shorten the pressing time, it is preferable that the pressing is performed at the glass transition temperature (Tg) or higher of the binder resin 4. For example, the press temperature can be 0 to 180 ° C., may be in the temperature range of room temperature (for example, 25 ° C.) to 100 ° C., or may be 30 to 100 ° C.

Next, a method of using the heat conductive sheet supply form 1 will be described. First, the release film 2 is peeled off from the supply form 1 of the heat conductive sheet. When the release film 2 is peeled off from the heat conductive sheet supply form 1 in this way, a part of the components of the heat conductive sheet main body 3 (binder resin 4, heat conductive material 5 having shape anisotropy, and other heat conductive materials). A part of at least one of 6) is transferred to the release film 2. As described above, since the surface of the heat conductive sheet main body 3 immediately after the release film 2 is peeled from the heat conductive sheet supply form 1 has tack property, it is possible to suppress the positional deviation at the time of mounting the heat conductive sheet main body 3.

[Second Embodiment]
A second embodiment of the present technique is, for example, as shown in FIGS. 2 and 4, a heat conductive sheet main body 3A containing a binder resin 4 and scaly boron nitride 5A, wherein the scaly boron nitride 5A Is oriented in the thickness direction B of the heat conductive sheet body 3A, and both sides of the heat conductive sheet body 3A have tackiness. In other words, in the heat conductive sheet body 3A, the plane direction of the scaly boron nitride 5A (for example, the major axis a of the boron nitride 5A) may be oriented in the thickness direction B of the heat conductive sheet body 3A. As described above, since the heat conductive sheet main body 3A has tackiness on both sides, it is possible to suppress the positional deviation at the time of mounting the heat conductive sheet main 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 a heat conductive sheet except that the heat conductive composition containing the binder resin 4 and the scaly boron nitride 5A is used in the step A of the manufacturing method of the above-mentioned heat conductive sheet supply form 1. It can be produced by the same method as the production method of the supply form 1. That is, the heat conductive sheet main body 3A is molded by a step A1 for preparing a heat conductive composition containing a binder resin 4 and a scaly boron nitride 5A, and a step B1 for forming a molded body block from the heat conductive composition. It can be obtained by a manufacturing method including a step C1 of slicing a body block into a sheet to obtain a heat conductive sheet and a step D1 of arranging the surface of the heat conductive sheet between the release films 7. In this way, the heat conductive sheet main body 3A is sandwiched between the release films 7.

When the release film 7 is peeled from the heat conductive sheet body 3A sandwiched between the release films 7, a part of the components of the heat conductive sheet body 3A (at least one of the binder resin 4 and the scaly boron nitride 5A) is partly released from the release film 7. Transfer to. This means that both sides of the heat conductive sheet main body 3A have tackiness.

Immediately after peeling off the release film 7, the heat conductive sheet body 3A has a surface tack force when the heat conductive sheet body 3A is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and 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.

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

<Electronic equipment>
The heat conductive sheet main body 3 from which the release film 2 is peeled from the above-mentioned heat conductive sheet supply form 1 is arranged between the heating element and the heat radiating element, so that the heat generated by the heating element can be transferred to the heat radiating element. 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 heat radiating element, and a heat conductive sheet main body 3, and may further have other members, if necessary. In the following description, it is assumed that the heat conductive sheet main body 3 also includes the heat conductive sheet main body 3A.

The heating element is not particularly limited, and is, for example, an electric circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DRAM (Dynamic Random Access Memory), an integrated circuit element such as a flash memory, a transistor, and a resistor. Examples include electronic components that generate heat in the. Further, the heating element also includes a component that receives an optical signal such as an optical transceiver in a communication device.

The radiator is not particularly limited, and examples thereof include those used in combination with integrated circuit elements, transistors, optical transceiver housings, and the like such as heat sinks and heat spreaders. In addition to the heat spreader and heat sink, the radiator may be any one that conducts heat generated from a heat source and dissipates it to the outside. Examples include heat pipes, metal covers, and housings.

FIG. 5 is a cross-sectional view showing an example of a semiconductor device to which the heat conductive sheet main 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 is sandwiched between a heating element and a heat radiating element. The semiconductor device 50 shown in FIG. 5 includes an electronic component 51, a heat spreader 52, and a heat conductive sheet main body 3, and the heat conductive sheet main body 3 is sandwiched between the heat spreader 52 and the electronic component 51. The heat conductive sheet main body 3 is sandwiched between the heat spreader 52 and the heat sink 53 to form a heat radiating member that dissipates heat from 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 and between the heat spreader 52 and the heat sink 53, and can be appropriately selected depending on the configuration of the electronic device or the semiconductor device.

Hereinafter, examples of this technique will be described. The art is not limited to these examples.

<Example 1>
In Example 1, 33% by volume of silicone resin, 27% by volume of scaly boron nitride (D50 is 40 μm) having a hexagonal crystal shape, 20% by volume of aluminum nitride (1.2 μm of D50), and alumina. A resin composition for forming a heat conductive sheet was prepared by uniformly mixing 19% by volume of particles (D50 is 1 μm) and 1% by volume of a silane coupling agent. By the extrusion molding method, the resin composition for forming a 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 body block. Formed. A peeling PET film was attached to the inner surface of the mold so that the peeling surface was on the inside. The obtained molded block was sliced into a sheet having a thickness of 1 mm with a slicer to obtain a heat conductive sheet in which scaly boron nitride was oriented in the thickness direction of the sheet. The obtained heat conductive sheet was sandwiched between peeled PET films to obtain a heat conductive sheet supply form. The supply form of this 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) and 20% by volume of aluminum nitride (D50 is 1.5 μm) having a hexagonal crystal shape, and alumina. A resin composition for forming a heat conductive sheet is obtained by uniformly mixing 17% by volume of particles (1 μm of D50), 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 that it was prepared. The obtained heat conductive sheet was sandwiched between the peeled PET films to obtain a heat conductive sheet supply form. The supply form of this heat conductive sheet was left for one week (7 days).

<Comparative Example 1>
In Comparative Example 1, the heat conductive sheet obtained by the same method as in Example 1 was left for 7 days without being sandwiched between the peeled 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) and 20% by volume of aluminum nitride (D50 is 1.5 μm) having a hexagonal crystal shape, and alumina. A resin composition for forming a heat conductive sheet was prepared by uniformly mixing 19% by volume of particles (D50 is 1 μm) and 1% by volume of a silane coupling agent. Using this resin composition for forming a heat conductive sheet, a heat conductive sheet was obtained by the same method as in Example 1. It was left for 7 days without being sandwiched between the peeled PET films.

<Thermal conductivity>
The heat conductive sheet main body from which the PET film peeled from the supply form of the heat conductive sheet obtained in Examples 1 and 2 was peeled off, and the heat conductivity in the thickness direction of the heat conductive sheet obtained in Comparative Examples 1 and 2 ( W / m · K) were measured respectively. Specifically, using a thermal resistance measuring device compliant with ASTM-D5470, a load of 1 kgf / cm ² is applied, and the thermal conductivity of the heat conductive sheet body or the heat conductive sheet immediately after production and after being left for 7 days after production is applied. Was measured. The results are shown in Table 1.

<Relative density>
With respect to the heat conductive sheet main body obtained in Examples 1 and 2 and the heat conductive sheet obtained in Comparative Examples 1 and 2, the volume obtained from the vertical and horizontal lengths and thickness and the heat conductive sheet main body or the heat conductive sheet The specific gravity was determined by measuring the weight. The results are shown in Table 1.

<Heat conduction sheet after slicing>
In the column of "heat conductive sheet after slicing" in Table 1, "sandwiched between PET" means that the obtained heat conductive sheet is sandwiched between peeled PET films (Examples 1 and 2). Represents. Further, "not sandwiched between PETs" means a case where the obtained heat conductive sheet is not sandwiched between the peeled PET films (Comparative Examples 1 and 2).

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

<Transfer after peeling off the sheet>
When the heat conductive sheet supply form immediately after 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 heat conductive sheet supply form, this PET was obtained. It was visually confirmed whether or not the trace (white) of the heat conductive sheet body had adhered to the film. Further, in Comparative Examples 1 and 2, when the heat conductive sheet immediately after being obtained was sandwiched between the peeled PET films, pressed at 0.5 MPa for 30 seconds, and then the peeled PET film was peeled off. It was visually confirmed whether or not the trace (white) of the heat conductive sheet adhered to this PET film. The results are shown in Table 1.

<Tack force immediately after making a sheet>
Immediately after the heat conductive sheet supply form obtained in Examples 1 and 2 was pressed at 0.5 MPa for 30 seconds and the PET film peeled from the heat conductive sheet supply form was peeled off (within 3 minutes). The tack force (gf) on the surface of the heat conductive sheet body when the heat conductive sheet body was pushed in by 50 μm at 2 mm / sec and pulled out at 10 mm / sec with a probe having a diameter of 5.1 mm was determined. Further, the heat conductive sheet immediately after being obtained in Comparative Examples 1 and 2 was also sandwiched between the peeled PET films and pressed at 0.5 MPa for 30 seconds, and then immediately after the peeled PET film was peeled off (). Within 3 minutes), the tack force (gf) of the surface of the heat conductive sheet when the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec was determined. The results are shown in Table 1.

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

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 the release film was peeled from the heat conductive sheet had tackiness. rice field. Further, in the supply form of the heat conductive sheet in Examples 1 and 2, since the surface of the heat conductive sheet main body immediately after the release film was peeled from the heat conductive sheet main body had tackiness, the heat conduction was performed on the aluminum plate. It turned out that it was fixed when the seat body was placed. From this, it was suggested that the supply form of the heat conductive sheet in Examples 1 and 2 can suppress the positional deviation at the time of mounting the heat conductive sheet main body.

On the other hand, in Comparative Examples 1 and 2, since the heat conductive sheet not sandwiched by the release film was used, the surface of the heat conductive sheet does not have tackiness as compared with the supply form of the heat conductive sheet of Examples 1 and 2. It turned out. Further, it was found that the heat conductive sheet in Comparative Examples 1 and 2 was not fixed when the heat conductive sheet was placed on the aluminum plate. From this, it was suggested that it is difficult for the heat conductive sheet in Comparative Examples 1 and 2 to suppress the positional deviation when the heat conductive sheet is mounted.

1 Supply form of heat conductive sheet, 2 release film, 3, 3A heat conduction sheet body, 4 binder resin, 5 heat conductive material with shape anisotropy, 5A scaly boron nitride, a long axis, b thickness, c Short axis, 6 other heat conductive materials, 7 release film, 8 aluminum plate, 50 semiconductor device, 51 electronic parts, 52 heat spreader, 53 heat sink

Claims (16)

It is a supply form of the heat conductive sheet in which the heat conductive sheet main body is sandwiched between the release films.
The heat conductive sheet body contains a binder resin and a heat conductive material having shape anisotropy.
The long axis of the heat conductive material having the shape anisotropy is oriented in the thickness direction of the heat conductive sheet body.
The above binder resin is a silicone resin,
The heat conductive material having the above shape anisotropy is scaly boron nitride or carbon fiber.
A supply form of a heat conductive sheet in which the tack force of the heat conductive sheet body immediately after the release film is peeled from the heat conductive sheet body is 75 gf or more in the following measuring method .
Measuring method: Immediately after peeling the release film from the heat conductive sheet main body, the heat conductive sheet main body is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and pulled out at 10 mm / sec. The tack force measured by the measurement method of the heat conductive sheet main body sandwiched between the release films is increased as compared with the tack force measured by the measurement method of the heat conductive sheet not sandwiched by the release film. The supply form of the heat conductive sheet according to claim 1. The supply form of the heat conductive sheet according to claim 1 or 2, wherein the heat conductive material having the shape anisotropy is scaly boron nitride. The supply form of the heat conductive sheet according to any one of claims 1 to 3, wherein the tack force of the heat conductive sheet main body immediately after peeling the release film is 80 gf or more in the measuring method. The heat conduction according to any one of claims 1 to 4, wherein when the release film is peeled from the heat conduction sheet main body, a part of the components of the heat conduction sheet body is transferred to the release film. Sheet supply form. The supply form of the heat conductive sheet according to any one of claims 1 to 5, wherein the heat conductive sheet main body further contains at least one of alumina, aluminum nitride, zinc oxide and aluminum hydroxide. The supply form of the heat conductive sheet according to any one of claims 1 to 6, wherein the release film is provided on both sides of the heat conductive sheet main body. The heat conductive sheet main body from which the release film is peeled off from the supply form of the heat conductive sheet according to any one of claims 1 to 7. An electronic device comprising the heat conductive sheet body according to claim 8. It is a method of manufacturing a supply form of a heat conductive sheet in which a heat conductive sheet main body is sandwiched between release films.
A step of preparing a heat conductive composition containing a binder resin and a heat conductive material having shape anisotropy, and
The process of forming a molded block from the above heat conductive composition and
The process of slicing the molded block into a sheet to obtain a heat conductive sheet,
It has a step of arranging the surface of the heat conductive sheet between the release films.
The above binder resin is a silicone resin,
The heat conductive material having the above shape anisotropy is scaly boron nitride.
A method for manufacturing a heat conductive sheet supply form, wherein the tack force of the heat conductive sheet main body immediately after peeling the release film is 75 gf or more in the following measurement method.
Measuring method: Immediately after peeling the release film from the heat conductive sheet main body, the heat conductive sheet main body is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and pulled out at 10 mm / sec. Contains binder resin and scaly boron nitride,
The heat conductive sheet body in which the scaly boron nitride is oriented in the thickness direction.
The above binder resin is a silicone resin,
A heat conductive sheet body having a tack force of 75 gf or more on the surface of the heat conductive sheet body when the heat conductive sheet body is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec . 11. The method according to claim 11, wherein the surface of the heat conductive sheet has a tack force of 80 gf or more when the heat conductive sheet body is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec. Heat conduction sheet body. A form of supplying a heat conductive sheet in which the heat conductive sheet main body according to claim 11 or 12 is sandwiched between release films. When the release film is peeled off from the heat conductive sheet body, at least a part of the binder resin constituting the heat conductive sheet body and the scaly boron nitride is transferred to the release film. Item 13. The supply form of the heat conductive sheet according to Item 13. The heat conductive sheet body according to claim 11 or 12, further comprising at least one of alumina, aluminum nitride, zinc oxide, and aluminum hydroxide. An electronic device comprising the heat conductive sheet body according to claim 11 or 12 between a heating element and a heat radiating element.

Images