Heat conductive sheet holder and method for manufacturing heat radiator

Abstract

To provide a heat conductive sheet holder by which a heat radiator can be efficiently manufactured.SOLUTION: A heat conductive sheet holder comprises a long carrier film, a plurality of heat conductive sheets, a long cover film covering the plurality of heat conductive sheets in this order, where the shortest distance between adjacent heat conductive sheets is 2 mm or more, the plurality of heat conductive sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of heat conductive sheets can be peeled from the cover film and the carrier film.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a heat conduction sheet holder and a heat dissipation device.

Background Art

[0002] In recent years, due to the increase in the heat generation amount caused by the high density of wiring and electronic component mounting in semiconductor packages using multilayer wiring boards, and the increase in the heat generation amount per unit area due to the high integration of semiconductor elements, it is desired to improve the heat dissipation performance from semiconductor packages.

[0003] A heat dissipation device that dissipates heat by sandwiching and closely attaching a heat conduction grease or a heat conduction sheet between a heat generating body such as a semiconductor package and a heat dissipation body such as aluminum or copper is generally used simply. Usually, the heat conduction sheet is superior to the heat conduction grease in workability when assembling the heat dissipation device.

[0004] As the heat conduction sheet, a resin sheet filled with a heat conduction filler is known. As a resin sheet excellent in heat conductivity filled with a heat conduction filler, resin sheets in which inorganic particles having high heat conductivity are selected as the heat conduction filler and the inorganic particles are oriented perpendicular to the sheet surface have been variously proposed. For example, a heat conduction sheet in which heat conduction fillers (boron nitride) are oriented in a direction substantially perpendicular to the sheet surface (see, for example, Patent Document 1), and a heat conduction sheet having a structure in which carbon fibers dispersed in a gel substance are oriented perpendicular to the sheet surface (see, for example, Patent Document 2) have been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Although it is possible to manufacture a heat dissipation device by sandwiching and closely attaching a heat conduction sheet described in Patent Documents 1 and 2 between a heat generating body such as a semiconductor package and a heat dissipation body such as aluminum or copper, due to the increasing demand for heat dissipation devices, there is a need for a method capable of efficiently manufacturing a heat dissipation device and a heat conduction sheet or the like used in such a method.

[0007] The present disclosure has been made in view of the above, and an object thereof is to provide a heat conduction sheet holder capable of efficiently manufacturing a heat dissipation device and a method for manufacturing a heat dissipation device using the heat conduction sheet holder.

Means for Solving the Problems

[0008] Specific means for solving the above problems include the following aspects. <1> A heat conduction sheet holder including a long carrier film, a plurality of heat conduction sheets, and a long cover film covering the plurality of heat conduction sheets in this order, wherein the plurality of heat conduction sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of heat conduction sheets are detachable from the cover film and the carrier film. <2> Further including a release layer between the carrier film and the plurality of heat conduction sheets, and the plurality of heat conduction sheets are detachable from the carrier film through the release layer. The heat conduction sheet holder according to <1>. <3> The heat conduction sheet holder according to <2>, including a plurality of the release layers arranged along the longitudinal direction of the carrier film, and one or more of the heat conduction sheets are arranged on each of the plurality of release layers. <4> When the cover film is arranged on the lower side in the vertical direction and the carrier film is arranged on the upper side in the vertical direction, the shape of the gap formed by the adjacent release layers and the adjacent heat conduction sheets arranged on the adjacent release layers respectively is a convex shape when viewed from the width direction of the heat conduction sheet holder according to <3>. <5> The heat conduction sheet holder according to any one of <1> to <4>, wherein the peeling force between the carrier film and the heat conduction sheet is greater than the peeling force between the cover film and the heat conduction sheet. <6> The heat conduction sheet holder according to any one of <1> to <5>, wherein the average thickness of the heat conduction sheet is 50 μm to 500 μm. <7> The heat conduction sheet holder according to any one of <1> to <6>, wherein the heat conduction sheet contains a heat conduction filler and a resin. <8> The heat conduction sheet holder according to any one of <1> to <7>, which is wound in a roll shape along the longitudinal direction. <9> In the width direction orthogonal to the longitudinal direction of the carrier film and the cover film, the widths of the carrier film and the cover film are larger than the width of the heat conduction sheet according to any one of <1> to <8>. <10> The heat conduction sheet holder according to any one of <1> to <9>, wherein the shortest distance between the adjacent heat conduction sheets is 2 mm or more. <11> The heat conduction sheet holder according to any one of <1> to <10>, wherein no cuts are generated on the surface of the carrier film.

[0009] <12> A method for manufacturing a heat dissipation device, comprising interposing the heat conduction sheet between a heat generating body and a heat dissipating body using the heat conduction sheet holder according to any one of <1> to <11>, the method comprising: a step of peeling the cover film from the heat conduction sheet holder; a step of pressing the heat conduction sheet against one of the heat generating body and the heat dissipating body in the heat conduction sheet holder from which the cover film has been peeled; a step of peeling the carrier film from the heat conduction sheet to which one of the heat generating body and the heat dissipating body is adhered; and a step of pressing the other of the heat generating body and the heat dissipating body against the side of the heat conduction sheet opposite to the side to which one of the heat generating body and the heat dissipating body is adhered.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a heat conduction sheet holder capable of efficiently manufacturing a heat dissipation device, and a method for manufacturing a heat dissipation device using this heat conduction sheet holder.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present invention. In the present disclosure, the term "step" includes not only a step independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved. In the numerical range indicated by using "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, the content ratio of each component in the composition means the total content ratio of the plurality of substances corresponding to each component in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In the present disclosure, there may be a plurality of types of particles corresponding to each component. When there are a plurality of types of particles corresponding to each component in the composition, the particle diameter of each component means a value for the mixture of the plurality of types of particles present in the composition, unless otherwise specified. In the present disclosure, the term "layer" includes not only the case where it is formed over the entire region where the layer exists, but also the case where it is formed only in a part of the region when observing the region where the layer exists. In the present disclosure, the term "lamination" indicates stacking layers, and two or more layers may be bonded, or two or more layers may be detachable. In the present disclosure, the thickness of the layer is a value obtained by measuring the thicknesses at five points of the target layer and taking the arithmetic mean value. The thickness of the layer can be measured using a micrometer or the like. In the present disclosure, when the thickness of the layer can be directly measured, it is measured using a micrometer. On the other hand, when measuring the thickness of one layer or the total thickness of a plurality of layers, it may be measured by observing the cross-section of the measurement target using an electron microscope. When describing embodiments in the present disclosure with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Also, the sizes of the members in each drawing are conceptual, and the relative size relationships between the members are not limited thereto.

[0013] <Heat conduction sheet holder> The heat conduction sheet holder of the present disclosure includes a long carrier film, a plurality of heat conduction sheets, and a long cover film covering the plurality of heat conduction sheets in this order. The plurality of heat conduction sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of heat conduction sheets are detachable from the cover film and the carrier film.

[0014] In the heat conduction sheet holder of the present disclosure, a plurality of heat conduction sheets are arranged on a long carrier film, and the carrier film enables the conveyance of the plurality of heat conduction sheets together. Thereby, while conveying the plurality of heat conduction sheets from which the cover film has been peeled off together with the carrier film, the heat conduction sheets can be continuously mounted on a heating element, a heat radiator, etc. by attaching them to the heating element, the heat radiator, etc. As described above, it becomes possible to manufacture a heat dissipation device efficiently.

[0015] The heat conduction sheet holder of the present disclosure preferably has a configuration in which it is wound in a roll shape along the longitudinal direction. At this time, the heat conduction sheet holder may be wound around a winding core. By pulling out the heat conduction sheet holder wound in a roll shape and peeling the cover film from the heat conduction sheet, it becomes possible to continuously mount the heat conduction sheet on a heating element, a heat radiator, etc. in a roll-to-roll continuous process, and a heat dissipation device can be manufactured more efficiently.

[0016] (Carrier film) The heat conduction sheet holder of the present disclosure includes an elongated carrier film. The carrier film is an elongated film member for transporting the heat conduction sheet, and a plurality of heat conduction sheets are arranged at intervals along the longitudinal direction directly on the carrier film or via a release layer or the like described later. The carrier film is detachable from the heat conduction sheet.

[0017] The material of the carrier film is not particularly limited as long as it can transport a plurality of heat conduction sheets arranged directly on the carrier film or via a release layer or the like, and examples include resins such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyether naphthalate, and methylpentene.

[0018] The carrier film may be a single-layer film containing at least one of the above-mentioned resins, or may be a multilayer film in which two or more layers containing at least one of the above-mentioned resins are laminated.

[0019] From the viewpoint of easily peeling the carrier film from the heat conduction sheet, a release layer may be provided between the carrier film and the plurality of heat conduction sheets, and the carrier film may be detachable from the plurality of heat conduction sheets via the release layer. The release layer may be, for example, a release film surface-treated with a release agent such as a silicone-based or silica-based release agent. The material of the release film surface-treated with the release agent is the same as the material of the above-mentioned carrier film. Further, the release layer such as a release film may be provided on the carrier film via an adhesive layer, and in the heat conduction sheet holder of the present disclosure, the carrier film, the adhesive layer, the release layer, and the heat conduction sheet may be laminated in this order when viewed from the carrier film side.

[0020] The average thickness of the carrier film is not particularly limited and can be appropriately selected in consideration of the strength of the carrier film, the transportability of the heat conduction sheet, etc. Specifically, the average thickness of the carrier film is preferably 25 μm to 200 μm, more preferably 50 μm to 150 μm, and even more preferably 50 μm to 100 μm.

[0021] When a release layer is provided between the carrier film and the plurality of heat conduction sheets, the average thickness of the release layer is not particularly limited. From the viewpoints of the releasability of the heat conduction sheet and the miniaturization of the heat conduction sheet holder, it is preferably 0.01 μm to 30 μm, and more preferably 1 μm to 10 μm. When the release layer is a release film with a release agent surface-treated thereon, the average thickness of the release film is not particularly limited. From the viewpoints of ensuring the adhesive characteristics and the miniaturization of the heat conduction sheet holder, it is preferably 2 μm to 200 μm, more preferably 25 μm to 200 μm, even more preferably 50 μm to 150 μm, and particularly preferably 50 μm to 100 μm.

[0022] When an adhesive layer is provided between the release layer and the carrier film, examples of the adhesive used for the adhesive layer include generally used acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, silicone adhesives, and mixed adhesives thereof. The adhesive layer may contain components other than the adhesive, and may contain a crosslinking agent, an adhesion promoter, etc. The average thickness of the adhesive layer is not particularly limited. From the viewpoints of ensuring the adhesive characteristics and the miniaturization of the heat conduction sheet holder, it is preferably 2 μm to 200 μm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 50 μm.

[0023] (Cover film) The heat conduction sheet holder of the present disclosure includes a long cover film. The cover film is a long member for covering and protecting a plurality of heat conduction sheets. The cover film is separable from the heat conduction sheet.

[0024] The cover film is not particularly limited, and examples thereof include the aforementioned resin films that can be included in the carrier film, paper films such as high-quality paper, coated paper, kraft paper, glassine paper, recycled paper, and metal foils such as aluminum. Among them, from the viewpoint of easily peeling the cover film from the heat conduction sheet, a paper film is preferred. The cover film may be a single-layer film composed of any one of the aforementioned films, metal foils, etc., or may be a multilayer film in which two or more layers of the aforementioned films, metal foils, etc. are laminated.

[0025] Also, a release layer may be provided on a plurality of surfaces of the cover film on the heat conduction sheet side, and the cover film may be peelable from the plurality of heat conduction sheets via the release layer. The release layer may be, for example, a layer containing a release agent such as a silicone-based or silica-based release agent. When the cover film is a paper film, from the viewpoint of suppressing the penetration of the release agent into the paper film, a layer containing polyethylene or the like that functions as a blocking agent may be disposed between the layer containing the release agent and the paper film.

[0026] The average thickness of the cover film is not particularly limited, and from the viewpoints of the strength of the cover film and the miniaturization of the heat conduction sheet holder, it is preferably 25 μm to 200 μm, more preferably 50 μm to 150 μm, and even more preferably 75 μm to 150 μm. Here, when a release layer, a layer containing polyethylene or the like as necessary, etc. are provided on a plurality of surfaces of the cover film on the heat conduction sheet side, the average thickness of the cover film means the total average thickness including the release layer and the like.

[0027] In the heat conduction sheet holder of the present disclosure, it is preferable that there are no cuts on the surface of the cover film, carrier film or release film, preferably on the surface on the heat conduction sheet side, and it is more preferable that there are no cuts resulting from cutting by dicing, laser processing, etc. In particular, it is preferable that there are no cuts on the surface of the cover film or carrier film, and it is more preferable that there are no cuts on the surface of the carrier film. When there are no cuts on these films, when tensile stress or the like is applied to the heat conduction sheet holder, breakage or deformation of these films is suppressed. As a result, problems such as the inability to continuously press the heat conduction sheet onto the adherend using the heat conduction sheet holder, and the relative positions of a plurality of heat conduction sheets shifting in the heat conduction sheet holder, making it impossible to accurately press the heat conduction sheet onto the adherend, are suppressed. In particular, since there are no cuts in the carrier film, even when the heat conduction sheet is pressed onto the adherend in a continuous process by the method shown in FIG. 3 as described later, breakage of the carrier film due to tensile stress or the like, and displacement of the heat conduction sheet on the carrier film are preferably suppressed.

[0028] In the heat conduction sheet holder of the present disclosure, it is preferable that the peeling force between the carrier film and the heat conduction sheet is greater than the peeling force between the cover film and the heat conduction sheet. Thereby, when peeling the cover film from the heat conduction sheet holder, it is possible to suppress peeling occurring between the carrier film and the heat conduction sheet, and the heat conduction sheet adhering to the peeled cover film.

[0029] For example, by providing a release layer between the carrier film and a plurality of heat conduction sheets, providing a release layer on the surface of the cover film on the heat conduction sheet side, or changing the type of release agent contained in these release layers, the peeling force between the cover film and the heat conduction sheet and the peeling force between the carrier film and the heat conduction sheet may be adjusted.

[0030] When a release layer is provided between the carrier film and the plurality of heat conduction sheets, the peel force between the release layer and the heat conduction sheet is preferably greater than the peel force between the cover film and the heat conduction sheet. Preferably.

[0031] The peel force between the cover film and the heat conduction sheet is preferably 0 mN / 25 mm to 30 mN / 25 mm, more preferably 0 mN / 25 mm to 10 mN / 25 mm, and even more preferably 0 mN / 25 mm to 5 mN / 25 mm. Here, a peel force of 0 mN / 25 mm indicates that the cover film has already peeled off when it is attached to a tensile testing machine so as to pull it in a direction perpendicular to the interface with the heat conduction sheet. The peel force between the cover film and the heat conduction sheet of the present disclosure is the maximum value of the peel strength when a laminated film with a width of 25 mm is prepared and the cover film is peeled off from the heat conduction sheet by pulling it in a direction perpendicular to the interface with the heat conduction sheet using a tensile testing machine under the conditions of a tensile speed of 100 mm / min and a temperature of 23°C.

[0032] The peel force between the carrier film and the heat conduction sheet, preferably the peel force between the release layer disposed between the carrier film and the heat conduction sheet and the heat conduction sheet, is preferably 5 mN / 25 mm to 50 mN / 25 mm, more preferably 10 mN / 25 mm to 30 mN / 25 mm, and even more preferably 12 mN / 25 mm to 30 mN / 25 mm. The peel force between the carrier film or the release layer of the present disclosure and the heat conduction sheet is the maximum value of the peel strength when a laminated film with a width of 25 mm is prepared and the carrier film or the release layer is peeled off from the heat conduction sheet by pulling it in a direction perpendicular to the interface with the heat conduction sheet using a tensile testing machine under the conditions of a tensile speed of 100 mm / min and a temperature of 23°C.

[0033] The peel strength between the carrier film and the heat conduction sheet (preferably the peel strength between the release layer disposed between the carrier film and the heat conduction sheet and the heat conduction sheet) is preferably greater than the peel strength between the cover film and the heat conduction sheet, and the difference between them is preferably 5 mN / 25 mm to 30 mN / 25 mm, more preferably 10 mN / 25 mm to 25 mN / 25 mm, and even more preferably 15 mN / 25 mm to 20 mN / 25 mm.

[0034] The sheet-like material such as the heat conduction sheet may have an adhesive component on the surface facing the adherend from the viewpoint of adhesiveness to the adherend. In the sheet-like material holder, since the sheet-like material is held in a state where the cover film does not contact the sheet-like material, the adhesion of the sheet-like material to the cover film due to the adhesive component is suppressed.

[0035] (Heat conduction sheet) The heat conduction sheet holder of the present disclosure includes a plurality of heat conduction sheets between a long carrier film and a long cover film, and the plurality of heat conduction sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film.

[0036] The average thickness of the heat conduction sheet is not particularly limited and can be appropriately selected according to the purpose. Specifically, the average thickness of the heat conduction sheet can be 50 μm to 500 μm, and from the viewpoints of thermal conductivity and adhesion, it is preferably 60 μm to 300 μm, and more preferably 70 μm to 200 μm.

[0037] The shape of the main surface of the heat conduction sheet is not particularly limited and may be appropriately changed according to the shapes of the heat generating body and the heat radiating body to which the heat conduction sheet is to be adhered. The shape of the main surface of the heat conduction sheet may be circular, elliptical, polygonal, or the like.

[0038] When the shape of the main surface of the heat conduction sheet is polygonal, preferably a quadrangular shape such as a rectangular shape, one side may have a length of 3 mm to 100 mm, or may have a length of 5 mm to 80 mm.

[0039] When the shape of the main surface of the heat conduction sheet is rectangular, it is preferable that a plurality of heat conduction sheets are arranged such that two opposite sides of the main surface are along the longitudinal direction of the carrier film. At this time, the ratio (width direction length / longitudinal direction length) of the length of the two sides along the longitudinal direction of the carrier film (longitudinal direction length) to the length of the two sides along the width direction orthogonal to the longitudinal direction of the carrier film (width direction length) may be 0.1 to 5, may be 0.2 to 4, or may be 0.3 to 3.

[0040] Regarding a plurality of heat conduction sheets arranged at intervals in the longitudinal direction of the carrier film and the cover film, the shortest distance between adjacent heat conduction sheets may be 2 mm or more, may be 2 mm to 100 mm, may be 5 mm to 60 mm, or may be 5 mm to 30 mm. When the shortest distance between adjacent heat conduction sheets is 2 mm or more, when the heat conduction sheet is pressure-bonded to an adherend such as a heating element or a heat sink, it is possible to suppress another heat conduction sheet adjacent to the heat conduction sheet to be pressure-bonded from interfering with the pressure-bonding to the adherend. As a result, damage to another heat conduction sheet and unintentional adhesion of another heat conduction sheet to the adherend can be suppressed. Further, when the shortest distance between adjacent heat conduction sheets is 100 mm or less, the productivity is excellent when the heat conduction sheet is pressure-bonded to an adherend such as a heating element or a heat sink.

[0041] The heat conduction sheet holder of the present disclosure may include a plurality of release layers arranged along the longitudinal direction of the carrier film between the carrier film and the plurality of heat conduction sheets, and one or more heat conduction sheets may be arranged on each of the plurality of release layers. Also, two or more heat conduction sheets may be arranged on each of the plurality of release layers, and 2 to 50 heat conduction sheets may be arranged. By arranging a plurality of release layers, it is possible to suppress the deflection of the release layer and the displacement of the heat conduction sheet due to the deflection.

[0042] Furthermore, when the heat conduction sheet holder of the present disclosure is arranged such that the cover film is on the lower side in the vertical direction and the carrier film is on the upper side in the vertical direction, the shape of the gap formed by the adjacent heat conduction sheets, which are respectively arranged on the adjacent release layers, is preferably convex when viewed from the width direction of the heat conduction sheet holder. As a result, on the surface where the heat conduction sheets of the plurality of release layers are arranged, no heat conduction sheets are arranged at both longitudinal ends, and the carrier film tends to be easily peeled off from the heat conduction sheet.

[0043] When the shape of the aforementioned gap is convex when viewed from the width direction of the heat conduction sheet holder, the ratio (lower side in the vertical direction of the convex shape / upper side in the vertical direction of the convex shape) of the upper side in the vertical direction of the convex shape, which is the shortest distance between adjacent release layers, to the lower side in the vertical direction of the convex shape, which is the shortest distance between adjacent heat conduction sheets, may be greater than 1 and 300 or less, may be 1.2 to 50, or may be 1.5 to 10.

[0044] When the shape of the aforementioned gap is convex when viewed from the width direction of the heat conduction sheet holder, the ratio (upper side in the vertical direction of the convex shape / height of the convex shape) of the height of the convex shape to the upper side in the vertical direction of the convex shape, which is the shortest distance between adjacent release layers, may be 0.1 to 1000, may be 0.5 to 100, or may be 1 to 50.

[0045] The length in the width direction of the carrier film and the length in the width direction of the cover film are preferably greater than the length in the width direction of the heat conduction sheet. Since the length in the width direction of the carrier film is greater than the length in the width direction of the heat conduction sheet, the carrier film can be easily transported, and the carrier film can be easily peeled off from the heat conduction sheet. Also, since the length in the width direction of the cover film is greater than the length in the width direction of the heat conduction sheet, the heat conduction sheet can be suitably protected, and the cover film can be easily peeled off from the heat conduction sheet.

[0046] The ratio of the widthwise length of the carrier film to the widthwise length of the heat conduction sheet (widthwise length of the carrier film / widthwise length of the heat conduction sheet) is preferably greater than 1 and not more than 15, more preferably 1.05 to 10, and even more preferably 1.1 to 5.

[0047] The ratio of the widthwise length of the cover film to the widthwise length of the heat conduction sheet (widthwise length of the cover film / widthwise length of the heat conduction sheet) is preferably greater than 1 and not more than 15, more preferably 1.05 to 10, and even more preferably 1.1 to 5.

[0048] From the perspective of transportability, in the heat conduction sheet holder of the present disclosure, it is preferable that no heat conduction sheet is arranged at both ends in the width direction of the carrier film. More preferably, a plurality of sprocket holes for transporting the carrier film are provided at regular intervals along the longitudinal direction at both ends of the carrier film. Furthermore, by providing a plurality of sprocket holes at regular intervals, it becomes easy to arrange a plurality of heat conduction sheets at regular intervals in the longitudinal direction of the carrier film based on the interval between the sprocket holes, and it also becomes easy to position the heat conduction sheet when pressing it against one of the heating element and the heat sink.

[0049] The center-to-center distance between adjacent sprocket holes may be 2 mm to 10 mm, or may be 3 mm to 6 mm. Also, the equivalent diameter of the circle of the sprocket hole may be 0.5 mm to 5 mm, or may be 1 mm to 3 mm.

[0050] In the heat conduction sheet used in the present disclosure, from the viewpoint that the heat conduction sheet is likely to be crushed and easily adhere to the other of the heating element and the heat radiator under the high-temperature pressing conditions in the second pressing step described later, the compression elastic modulus when the compression stress at 150 °C is 0.1 MPa is preferably 1.4 MPa or less, more preferably 1.3 MPa or less, and even more preferably 1.2 MPa or less. The lower limit of the compression elastic modulus when the compression stress at 150 °C is 0.1 MPa is not particularly limited. The above compression elastic modulus may be 0.5 MPa or more, or may be 0.7 MPa or more.

[0051] The compression elastic modulus of the heat conduction sheet can be measured using a compression test apparatus (for example, INSTRON 5948 Micro Tester (manufactured by INSTRON)). A load is applied to the heat conduction sheet in the thickness direction, and the displacement (mm) and the load (N) are measured. The strain (dimensionless) obtained by displacement (mm) / thickness (mm) is plotted on the horizontal axis, and the stress (MPa) obtained by load (N) / area (mm 2 ) is plotted on the vertical axis, and the slope at a predetermined stress is taken as the compression elastic modulus (MPa). Specifically, for example, it can be measured by the method described in the examples.

[0052] In the heat conduction sheet used in the present disclosure, the tack force at 25 °C is preferably 5.0 N·mm or more, more preferably 6.0 N·mm or more, and even more preferably 7.0 N·mm or more. When the tack force is 5.0 N·mm or more, when warping occurs in the heat dissipation device including the heat conduction sheet and the distance between the heating element and the heat radiator increases, it is possible to suppress the heat conduction sheet from peeling off from the heating element and the heat radiator. The upper limit value of the tack force is not particularly limited. The above tack force may be 20.0 N·mm or less, or may be 15.0 N·mm or less.

[0053] The tack force of the heat conduction sheet at 25 °C is measured using a universal physical property tester (for example, Texture Analyzer It can be measured using a Narizer (Eihiro Seiki Co., Ltd.). At 25°C (room temperature), a probe with a diameter of 7 mm is pressed against the heat conduction sheet with a load of 40 N and held for 10 seconds. Then, the area obtained by integrating the load-displacement curve when the probe is pulled up is defined as the tack force (N·mm) at 25°C.

[0054] Preferably, for the heat conduction sheet used in the present disclosure, both the compression elastic modulus when the compression stress at 150°C is 0.1 MPa and the tack force at 25°C satisfy the above conditions.

[0055] As described above, a heat conduction sheet with a compression elastic modulus of 1.4 MPa or less when the compression stress at 150°C is 0.1 MPa is a soft sheet, and a heat conduction sheet with a tack force of 5.0 N·mm or more at 25°C is a high-adhesion sheet. Therefore, when attempting to pick up such a soft or high-adhesion heat conduction sheet itself and mount it on a heating element, a heat sink, etc., the soft or high-adhesion heat conduction sheet itself is likely to deform, break, etc., and it is difficult to easily peel the soft or high-adhesion heat conduction sheet from a base material such as a protective sheet, or the heat conduction sheet itself after peeling is deformed, broken, etc., and there is a problem that it cannot be used for mounting on a heating element, a heat sink, etc.

[0056] On the other hand, in the heat conduction sheet holder of the present disclosure, when mounting the heat conduction sheet on a heating element, a heat sink, etc., the above-mentioned picking up is not necessary, and the heat conduction sheet can be continuously mounted on the heating element, the heat sink, etc. while suppressing deformation, breakage, etc. of the heat conduction sheet itself. Therefore, it is excellent in the handleability of the heat conduction sheet and the manufacturing efficiency of the heat dissipation device.

[0057] The above compression elastic modulus and the above tack force can be obtained, for example, by adjusting the blending ratio of each component used in the heat conduction sheet. Hereinafter, the preferred composition, etc. of the heat conduction sheet will be described.

[0058] ≪Thermal Conductive Filler≫ The heat conduction sheet preferably contains a heat conduction filler. The heat conduction filler is not particularly limited as long as it is a filler having heat conductivity. Examples of the heat conduction filler include particles of high heat conductivity metals such as silver, copper, and aluminum, particles of ceramics such as alumina, aluminum nitride, boron nitride, and magnesium oxide, and graphite particles. Note that as the heat conduction filler, one type may be used alone, or two or more types may be used in combination.

[0059] As the heat conduction filler, particularly from the viewpoints of low thermal resistance and excellent heat conductivity, graphite particles are preferable, and at least one type of graphite particle selected from the group consisting of flaky particles, ellipsoidal particles, and rod-shaped particles described later is more preferable.

[0060] The mass average particle diameter (D50) of the heat conduction filler is measured using a laser diffraction particle size distribution analyzer (for example, "Microtrac Series MT3300" manufactured by Nikkiso Co., Ltd.) that applies the laser diffraction / scattering method, and corresponds to the particle diameter at which the weight cumulative is 50% when a weight cumulative particle size distribution curve is drawn from the small particle size side.

[0061] The particle size distribution of the heat conduction filler is not particularly limited, and may be a monodisperse system having a single peak in the particle size distribution with the particle size on the horizontal axis and the frequency on the vertical axis, or a polydisperse system having a plurality of peaks in the particle size distribution. Also, the particle size distribution may be narrow or wide.

[0062] The content of the heat conduction filler in the heat conduction sheet is preferably 15% to 50% by volume, more preferably 20% to 45% by volume, and even more preferably 25% to 40% by volume, for example, from the viewpoint of the balance between heat conductivity and adhesion to heat generating bodies, heat radiating bodies, etc. preferable. When the content of the heat conduction filler is 15% by volume or more, the heat conductivity tends to be further improved. When the content of the heat conduction filler is 50% by volume or less, the decrease in adhesiveness and adhesion to heat generating bodies, heat radiating bodies, etc. can be more effectively suppressed.

[0063] The content ratio (volume %) of the heat-conductive filler is a value obtained by the following formula. Content ratio (volume %) of the heat-conductive filler = (Aw / Ad) / ((Aw / Ad)+(Bw / Bd)+(Cw / Cd))×100 Aw: Mass composition (mass %) of the heat-conductive filler Bw: Mass composition (mass %) of the resin Cw: Mass composition (mass %) of other optional components Ad: Density of the heat-conductive filler Bd: Density of the resin Cd: Density of other optional components

[0064] As the heat-conductive filler, it may contain at least one kind of graphite particle selected from the group consisting of flaky particles, ellipsoidal particles, and rod-shaped particles. Further, when the graphite particles are flaky particles, the in-plane direction; when the graphite particles are ellipsoidal particles, the major axis direction; or when the graphite particles are rod-shaped particles, the major axis direction may be oriented in the thickness direction. With such a configuration, the heat-conductive sheet has a low thermal resistance and excellent thermal conductivity.

[0065] The shape of the graphite particles is preferably flaky. By selecting flaky graphite particles, the thermal conductivity tends to be further improved. This can be considered, for example, because flaky graphite particles are more easily oriented in a predetermined direction in the heat-conductive sheet. The six-membered ring plane refers to the plane in which six-membered rings are formed in the hexagonal crystal system and means the (0001) crystal plane.

[0066] Whether the six-membered ring plane in the crystal of the graphite particles is oriented in the in-plane direction of the flaky particles, the major axis direction of the ellipsoidal particles, or the major axis direction of the rod-shaped particles can be confirmed by X-ray diffraction measurement. The orientation direction of the six-membered ring plane in the crystal of the graphite particles can be specifically confirmed by the following method.

[0067] First, a measurement sample sheet is prepared in which the in-plane direction of the flaky particles, the major axis direction of the ellipsoidal particles, or the major axis direction of the rod-shaped particles of the graphite particles is oriented along the in-plane direction of the sheet. Specific methods for preparing the measurement sample sheet include, for example, the following methods.

[0068] A mixture of a resin and graphite particles in an amount of 10% by volume or more with respect to the resin is formed into a sheet. The "resin" used here is not particularly limited as long as it is a material that does not exhibit a peak that interferes with X-ray diffraction and is a material capable of forming a sheet. Specifically, amorphous resins having cohesive force as a binder, such as acrylic rubber, NBR (acrylonitrile-butadiene rubber), SIBS (styrene-isobutylene-styrene copolymer), etc., can be used.

[0069] The sheet of this mixture is pressed so that it becomes 1 / 10 or less of the original thickness, and a plurality of the pressed sheets are laminated to form a laminate. The operation of further crushing the laminate to 1 / 10 or less is repeated 3 times or more to obtain a measurement sample sheet. By this operation, in the measurement sample sheet, when the graphite particles are flaky particles, the plane direction; when they are ellipsoidal particles, the major axis direction; and when they are rod-shaped particles, the major axis direction are oriented along the plane direction of the measurement sample sheet.

[0070] X-ray diffraction measurement is performed on the surface of the measurement sample sheet produced as described above. The height H1 of the peak corresponding to the (110) plane of graphite that appears near 2θ = 77° and the height H2 of the peak corresponding to the (002) plane of graphite that appears near 2θ = 27° are measured. In this way In the produced measurement sample sheet, the value obtained by dividing H1 by H2 is 0 to 0.02.

[0071] From this, "the six-membered ring plane in the crystal of the graphite particles is oriented in the plane direction in the case of flaky particles, in the major axis direction in the case of ellipsoidal particles, and in the major axis direction in the case of rod-shaped particles" means that X-ray diffraction measurement is performed on the surface of the sheet containing the graphite particles, and the value obtained by dividing the height of the peak corresponding to the (110) plane of the graphite particles that appears near 2θ = 77° by the height of the peak corresponding to the (002) plane of the graphite particles that appears near 2θ = 27° is 0 to 0.02.

[0072] In the present disclosure, the X-ray diffraction measurement is performed under the following conditions. Apparatus: "D8 DISCOVER" manufactured by Bruker AXS K.K. X-ray source: CuKα with a wavelength of 1.5406 nm, 40 kV, 40 mA Step (measurement interval): 0.01° Step time: 720 sec

[0073] Here, "when the graphite particles are flaky particles, the plane direction; when the graphite particles are ellipsoidal particles, the major axis direction; and when the graphite particles are rod-shaped particles, the major axis direction are oriented in the thickness direction of the heat conduction sheet" means that the angle formed between the plane direction in the case of flaky particles, the major axis direction in the case of ellipsoidal particles, and the major axis direction in the case of rod-shaped particles and the surface of the heat conduction sheet (hereinafter also referred to as the "orientation angle") is 60° or more. The orientation angle is preferably 80° or more, more preferably 85° or more, and even more preferably 88° or more.

[0074] The orientation angle is the average value when observing the cross-section of the heat conduction sheet with an SEM (scanning electron microscope) and measuring the angle (orientation angle) formed between the plane direction in the case of flaky particles, the major axis direction in the case of ellipsoidal particles, and the major axis direction in the case of rod-shaped particles and the surface (main surface) of the heat conduction sheet for any 50 graphite particles.

[0075] The particle size of the graphite particles is not particularly limited. The average particle size of the graphite particles is preferably 1 / 2 to the average thickness of the heat conduction sheet. When the average particle size of the graphite particles is 1 / 2 or more of the average thickness of the heat conduction sheet, an efficient heat conduction path is formed in the heat conduction sheet, and the thermal conductivity tends to improve. When the average particle size of the graphite particles is equal to or less than the average thickness of the heat conduction sheet, the protrusion of the graphite particles from the surface of the heat conduction sheet is suppressed, and the adhesion to the surface of the heat conduction sheet tends to be excellent.

[0076] When using the laminated slice method as described in Japanese Patent Application Laid-Open No. 2008-280496, the particle diameter of the graphite particles used as raw materials is preferably 1 / 2 times or more of the average thickness of the heat conduction sheet as the mass average particle diameter, and may exceed the average thickness. The reason why the particle diameter of the graphite particles used as raw materials may exceed the average thickness of the heat conduction sheet is that, for example, even if it contains graphite particles with a particle diameter exceeding the average thickness of the heat conduction sheet, since the heat conduction sheet is formed by slicing each graphite particle, as a result, the graphite particles do not protrude from the surface of the heat conduction sheet. Also, when slicing each graphite particle in this way, a large number of graphite particles penetrating in the thickness direction of the heat conduction sheet are generated, and an extremely efficient heat conduction path is formed, and the thermal conductivity tends to be further improved.

[0077] When using the laminated slice method, the particle diameter of the graphite particles used as raw materials is more preferably 1 to 5 times the average thickness of the heat conduction sheet as the mass average particle diameter. When the mass average particle diameter of the graphite particles is 1 time or more the average thickness of the heat conduction sheet, a more efficient heat conduction path is formed, and the thermal conductivity is further improved. When it is 5 times or less the average thickness of the heat conduction sheet, it is possible to suppress the excessive increase in the area occupied by the surface portion of the graphite particles, and the decrease in adhesion can be suppressed.

[0078] The content rate of the graphite particles in the heat conduction filler is preferably, for example, 50% by volume to 100% by volume, more preferably 80% by volume to 100% by volume, still more preferably 95% by volume to 100% by volume, and particularly preferably 100% by volume with respect to the total volume of the heat conduction filler.

[0079] The heat conduction sheet may contain particles other than flaky particles, ellipsoidal particles, and rod-shaped particles as graphite particles, and may contain spherical graphite particles, artificial graphite particles, thinned graphite particles, acid-treated graphite particles, expanded graphite particles, carbon fiber flakes, etc. As the graphite particles, flaky particles are preferable, and from the viewpoint of high crystallinity and easy availability of large-sized flakes, flaky expanded graphite particles obtained by pulverizing sheet-shaped expanded graphite are preferable.

[0080] ≪Resin≫ The heat-conducting sheet preferably contains a resin. By containing a resin, the heat-conducting sheet tends to be excellent in flexibility and to obtain a heat-conducting sheet having good adhesion to a heating element, a heat radiator, etc.

[0081] The resin is not particularly limited, and may be, for example, a curable resin or a non-curable resin. Examples of the resin include epoxy resin, silicone, acrylic resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, polyurethane, polyimide silicone, thermosetting polyphenylene ether, thermosetting modified polyphenylene ether, polybutene, polyisoprene, polysulfide, acrylonitrile rubber, silicone rubber, hydrocarbon resin, terpene resin, terpene phenol resin, hydrogenated terpene phenol, etc. The resin may be used alone or in combination of two or more.

[0082] The content of the resin in the heat-conducting sheet is preferably selected according to the type of the resin and the desired flexibility, adhesive force, adhesion, sheet strength, hydrolysis resistance, etc. For example, the content rate of the resin is preferably 25% by volume to 75% by volume, more preferably 40% by volume to 70% by volume, and still more preferably 50% by volume to 65% by volume with respect to the total volume of the heat-conducting sheet.

[0083] ≪Other Components≫ The heat-conducting sheet may contain other components other than the heat-conducting filler and the resin according to the purpose. For example, the heat-conducting sheet may contain a flame retardant for the purpose of imparting flame retardancy.

[0084] The flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. For example, red phosphorus-based flame retardants and phosphate ester-based flame retardants can be mentioned. Among them, phosphate ester-based flame retardants are preferable from the viewpoints of excellent safety and improved adhesion due to the plasticizing effect.

[0085] As red phosphorus-based flame retardants, in addition to pure red phosphorus powder, those with various coatings applied for the purpose of enhancing safety or stability, masterbatch-formulated ones, etc. may also be used. Specifically, examples include Novared, Nova Excel, Nova Quel, and Nova Pellet (all are trade names) manufactured by Phosphorus Chemical Industry Co., Ltd.

[0086] As phosphate ester-based flame retardants, aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, and tributyl phosphate; aromatic phosphate esters such as triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, trixylenyl phosphate, cresyl-2,6-xylenyl phosphate, tris(t-butylated phenyl) phosphate, tris(isopropylated phenyl) phosphate, and triaryl isopropyl phosphate of phosphoric acid; aromatic condensed phosphate esters such as resorcinol bisdiphenyl phosphate, bisphenol A bis(diphenyl phosphate), and resorcinol bisdixylenyl phosphate, etc. can be mentioned. Among these, bisphenol A bis(diphenyl phosphate) is preferable because it has excellent hydrolysis resistance and excellent effect of improving adhesion due to its plasticizing effect.

[0087] The content of the flame retardant in the heat conduction sheet is not limited and can be used in an amount that exhibits flame retardancy. It is preferably 40% by volume or less, and more preferably 30% by volume or less from the viewpoint of suppressing the deterioration of thermal resistance due to the bleeding of the flame retardant component to the surface of the heat conduction sheet.

[0088] The heat conduction sheet may contain additives such as antioxidants, radical trap agents, and pH adjusters as required, and preferably may contain antioxidants. The content of these additives is preferably 5% by volume or less, more preferably 3% by volume or less, and even more preferably 1% by volume or less in the heat conduction sheet.

[0089] 〔Method for manufacturing heat conduction sheet holder〕 Examples of the method for manufacturing a heat conduction sheet holder include the following. The manufacturing method includes a step of preparing a composition containing a heat conduction filler, a resin, and, if necessary, other components (also referred to as the "preparation step"), a step of forming the composition into a sheet to obtain a sheet (also referred to as the "sheet production step"), a step of stacking a plurality of the sheets, folding one of the sheets, or winding one of the sheets to produce a laminate (also referred to as the "laminate production step"), a step of slicing side end faces of the laminate (slicing step), and a step of sandwiching a plurality of sliced heat conduction sheets between a cover film and a carrier film and laminating the plurality of heat conduction sheets (laminating step).

[0090] The heat conduction sheets included in the heat conduction sheet holder manufactured by such a method are likely to form an efficient heat conduction path, and thus tend to be excellent in high heat conductivity and adhesion.

[0091] <Preparation Step> The preparation of the composition constituting the heat conduction sheet may be carried out by any method as long as the heat conduction filler, the resin, and, if necessary, other components can be uniformly mixed, and is not particularly limited. Also, a commercially available composition may be obtained and prepared. For details of the preparation of the composition, reference can be made to paragraph

[0033] of JP-A-2008-280496.

[0092] <Sheet Production Step> The sheet production step may be carried out by any method as long as the composition obtained in the previous step can be formed into a sheet, and is not particularly limited. For example, it is preferably carried out using at least one molding method selected from the group consisting of rolling, pressing, extrusion, and coating. For details of the sheet production step, reference can be made to paragraph

[0034] of JP-A-2008-280496.

[0093] <Laminate Production Step> The laminate manufacturing process forms a laminate of the sheets obtained in the previous process. The laminate is not limited to, for example, a form in which a plurality of independent sheets are stacked in order, and may be a form in which one sheet is folded without being cut, or a form in which one of the sheets is wound. For details of the laminate manufacturing process, reference can be made to paragraphs

[0035] to

[0037] of JP-A-2008-280496.

[0094] <Slicing Process> The slicing process may be any method as long as the side end faces of the laminate obtained in the previous process can be sliced, and is not particularly limited. From the viewpoint of forming an extremely efficient heat conduction path by the graphite particles penetrating in the thickness direction of the heat conduction sheet and further improving the heat conductivity, it is preferable to slice at a thickness of 2 times or less the mass average particle diameter of the graphite particles. For details of the slicing process, reference can be made to paragraph

[0038] of JP-A-2008-280496.

[0095] <Laminating Process> In the laminating process, as long as a plurality of sliced heat conduction sheets are sandwiched between a cover film and a carrier film or between a cover film and a release film and the plurality of heat conduction sheets are attached to the cover film and the carrier film or the release film, any method may be used and it is not particularly limited. For example, after cutting the sliced heat conduction sheets into a predetermined size, arranging the plurality of heat conduction sheets on a cover film, a carrier film or a release film, and then sandwiching the arranged plurality of heat conduction sheets between a cover film and a carrier film or between a cover film and a release film, and bonding the heat conduction sheets thereto to obtain a heat conduction sheet holder may be acceptable. In addition to the above method, for example, arranging the sliced heat conduction sheets on a cover film, a carrier film or a release film, cutting the heat conduction sheets by punching or the like to have a predetermined size, and then sandwiching the plurality of cut heat conduction sheets between a cover film and a carrier film or between a cover film and a release film, and bonding the heat conduction sheets thereto to obtain a heat conduction sheet holder may also be acceptable.

[0096] For example, in the laminating process, a long heat-conducting sheet is placed on a cover film, a carrier film, or a release film, and the long heat-conducting sheet is cut by dicing, laser processing, etc., so that a plurality of heat-conducting sheets can also be placed on the cover film, the carrier film, or the release film. However, when the long heat-conducting sheet is cut by dicing, laser processing, etc., the cover film, the carrier film, or the release film on which the long heat-conducting sheet is placed may also be partially cut in the thickness direction, resulting in cuts. When cuts occur on these films, if tensile stress or the like is applied to the obtained heat-conducting sheet holder, these films may break or deform. As a result, problems such as the inability to continuously press the heat-conducting sheet onto the adherend using the heat-conducting sheet holder, and the relative positions of the plurality of heat-conducting sheets shifting in the heat-conducting sheet holder, making it impossible to accurately press the heat-conducting sheet onto the adherend, are likely to occur. In particular, such problems are likely to occur when cuts are made in the cover film or the carrier film, and when cuts are made in the carrier film, the continuous process using the method shown in FIG. 3 described below becomes difficult.

[0097] From the above points, in the laminating process, it is preferable to include placing a plurality of heat-conducting sheets on a cover film, a carrier film, or a release film, or cutting the heat-conducting sheet placed on the cover film, the carrier film, or the release film by punching or the like. Thereby, cuts in the cover film, the carrier film, or the release film do not occur or are suppressed, and breakage, deformation, etc. of the film when tensile stress or the like is applied to the heat-conducting sheet holder can be preferably suppressed. Furthermore, unlike the case where the long heat-conducting sheet is cut by dicing, laser processing, etc., it also becomes easy to arrange a plurality of heat-conducting sheets so that the shortest distance between adjacent heat-conducting sheets is 2 mm or more.

[0098] <Method for manufacturing a heat dissipation device> The method for manufacturing a heat dissipation device according to the present disclosure is a method for manufacturing a heat dissipation device in which the heat conduction sheet is interposed between a heat generating body and a heat dissipating body using the heat conduction sheet holder of the present disclosure, and includes a step of peeling the cover film from the heat conduction sheet holder, and in the heat conduction sheet holder from which the cover film has been peeled, a step of crimping the heat conduction sheet to one of the heat generating body and the heat dissipating body, a step of peeling the carrier film from the heat conduction sheet to which one of the heat generating body and the heat dissipating body is adhered, and a step of crimping the other of the heat generating body and the heat dissipating body to the side of the heat conduction sheet opposite to the side to which one of the heat generating body and the heat dissipating body is adhered. In the heat conduction sheet holder from which the cover film has been peeled, a step of crimping the heat conduction sheet to one of the heat generating body and the heat dissipating body, a step of peeling the carrier film from the heat conduction sheet to which one of the heat generating body and the heat dissipating body is adhered, and a step of crimping the other of the heat generating body and the heat dissipating body to the side of the heat conduction sheet opposite to the side to which one of the heat generating body and the heat dissipating body is adhered.

[0099] In the heat dissipation device obtained by the manufacturing method of the present disclosure, since the heat generating body and the heat dissipating body are laminated via the heat conduction sheet, heat from the heat generating body can be efficiently conducted to the heat dissipating body. Further, when removing the heat dissipating body from the heat generating body, the heat conduction sheet can be easily removed.

[0100] The manufacturing method of the present disclosure includes a step of peeling the cover film from the heat conduction sheet holder. For example, when the heat conduction sheet holder of the present disclosure is wound in a roll shape, the cover film may be peeled while feeding out the heat conduction sheet holder in a state where the roll-shaped heat conduction sheet holder is attached to a rotatable feeding roll.

[0101] The manufacturing method of the present disclosure includes a step (hereinafter, also referred to as "first crimping step") of crimping the heat conduction sheet to one of the heat generating body and the heat dissipating body in the heat conduction sheet holder from which the cover film has been peeled. At this time, in a continuous process of roll-to-roll, the heat conduction sheet holder from which the cover film has been peeled may be conveyed, and a process of crimping the heat conduction sheet disposed on the heat conduction sheet holder to one of the heat generating body and the heat dissipating body may be performed.

[0102] Examples of the heating element include a semiconductor package in which a semiconductor chip is disposed on a substrate, a display, an LED, a lamp, an automotive power module, and an industrial power module. Examples of the heat sink include a heat sink using fins, plates, etc. of aluminum or copper, an aluminum or copper block connected to a heat pipe, an aluminum or copper block in which a cooling liquid is circulated by a pump inside, a Peltier element, and an aluminum or copper block including the same.

[0103] The pressure and heating temperature in the first crimping step are not particularly limited as long as the heat conductive sheet can be adhered to one of the heating element and the heat sink. For example, the aforementioned pressure may be 0.1 MPa to 4.0 MPa, or may be 0.15 MPa to 2.0 MPa. Further, the aforementioned heating temperature may be 15°C to 100°C, or may be 20°C to 35°C. When the heat conductive sheet is crimped to the heating element, the heating element may be heated to perform the crimping.

[0104] The manufacturing method of the present disclosure includes a step of peeling the carrier film from the heat conductive sheet adhered to one of the heating element and the heat sink. For example, after the heat conductive sheet is crimped to one of the heating element and the heat sink in the aforementioned crimping step, the crimping may be released to peel the carrier film from the heat conductive sheet. By this step, one of the heating element and the heat sink to which the heat conductive sheet is adhered can be obtained. Further, a release layer may be provided between the carrier film and the heat conductive sheet, and in this case, the carrier film may be peeled from the heat conductive sheet via the release layer.

[0105] In a roll-to-roll continuous process, the carrier film from which the heat conductive sheet has been peeled is attached to a take-up roll that can rotate on the upstream side in the conveyance direction, and by rotating the take-up roll and the aforementioned pay-out roll, while recovering the carrier film from which the heat conductive sheet has been peeled, a new heat conductive sheet may be conveyed, and the process of performing crimping with one of the new heating element and the heat sink may be continuously performed.

[0106] The manufacturing method of the present disclosure includes a step of pressing the other of the heating element and the heat sink on the side opposite to the side to which one of the heating element and the heat sink of the heat conduction sheet is adhered (hereinafter, also referred to as the "second pressing step"). By pressing the other of the heating element and the heat sink onto one of the heating element and the heat sink to which the heat conduction sheet is adhered in this step, a heat dissipation device in which the heat conduction sheet is interposed between the heating element and the heat sink can be obtained. The preferable conditions of the pressure and the heating temperature in the second pressing step are not particularly limited as long as the heat conduction sheet can be adhered to the other of the heating element and the heat sink. For example, the aforementioned pressure may be 0.1 MPa to 2.0 MPa, or may be 0.15 MPa to 1.0 MPa. Also, the aforementioned heating temperature may be 80°C to 180°C, or may be 100°C to 170°C. When pressing the heat conduction sheet with one side exposed onto the heating element, the pressing may be performed while heating the heating element.

[0107] In the manufacturing method of the present disclosure, the pressing conditions in the first pressing step and the second pressing step may be adjusted so that the ratio (compression ratio) of the thickness of the heat conduction sheet decreased after the second pressing step to the initial thickness of the heat conduction sheet before the first pressing step is 5% to 35%.

[0108] (An example of a heat conduction sheet holder) Hereinafter, an example of a heat conduction sheet holder will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view showing an example of the heat conduction sheet holder of the present disclosure. FIG. 2 is a view when looking at the region α corresponding to the dotted line portion of FIG. 1 from the side of the cover film 1. In FIG. 2, the cover film 1 is omitted. As shown in FIG. 1, the heat conduction sheet holder 10 includes a long carrier film 3, a plurality of heat conduction sheets 2, and a long cover film 1 in this order. Further, in the heat conduction sheet holder 10, a release film 4 and an adhesive layer 5 are arranged in this order between the carrier film 3 and the plurality of heat conduction sheets 2 when viewed from the side of the cover film 1. A plurality of release films 4 are arranged along the longitudinal direction of the carrier film 3, and nine heat conduction sheets are arranged on each of the plurality of release films. Also, the region α surrounded by the circular dotted line in FIG. 1 corresponds to the gap formed by the adjacent release films 4 and the adjacent heat conduction sheets 2 arranged on the adjacent release films, and its shape is convex when viewed from the front.

[0109] The heat conduction sheet holder 10 has a configuration in which it is wound in a roll shape along the longitudinal direction around a winding core 6. In FIG. 1, a part of the heat conduction sheet holder 10 wound in a roll shape is pulled out. In FIG. 1, the pulled-out portion of the heat conduction sheet holder 10 is emphasized more than the winding core 6, and the relative relationship between the sizes of the pulled-out portion and the winding core 6 is not limited to this. Also, in FIG. 1, the heat conduction sheet holder 10 is wound in a roll shape such that the cover film 1 is on the outside and the carrier film 3 is on the inside with respect to the central axis, but it is not limited to this, and the heat conduction sheet holder 10 may be wound in a roll shape such that the cover film 1 is on the inside and the carrier film 3 is on the outside with respect to the central axis.

[0110] The widthwise length of the carrier film 3 and the widthwise length of the cover film 1 are greater than the widthwise length of the heat conduction sheet 2. The heat conduction sheet 2 is not arranged at both ends in the width direction of the carrier film 3, and a plurality of sprocket holes 7 for conveying the carrier film are provided at both ends of the carrier film 3 at regular intervals along the longitudinal direction. The sprocket holes 7 provided at regular intervals are also used for positioning the heat conduction sheet 2 during the conveyance of the carrier film.

[0111] (An example of a method for manufacturing a heat dissipation device) Hereinafter, an example of a method for manufacturing a heat dissipation device will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing a part of the manufacturing process in an example of a method for manufacturing a heat dissipation device. In FIG. 3, the release film 4 and the adhesive layer 5 are omitted.

[0112] As shown in FIG. 3, the heat conduction sheet holder 10 wound in a roll shape is attached to the pay-out roll 11 that can rotate in the direction of arrow X, and the heat conduction sheet holder 10 is peeled from the cover film 1. The carrier film 3 of the heat conduction sheet holder 10 from which the cover film 1 has been peeled is attached to the take-up roll 16 that can rotate in the direction of arrow Z at a certain distance from the pay-out roll 11. A press 14 for pressing the heat conduction sheet 2 against the semiconductor chip 13, which is a heating element, is provided between the pay-out roll 11 and the take-up roll 16 in the conveyance direction.

[0113] A sprocket roller (not shown) is arranged between the pay-out roll 11 and the take-up roll 16, and the sprocket holes 7 are inserted into the sprocket pins provided at equal intervals on the surface of the sprocket roller. By rotating the pay-out roll 11 in the direction of arrow X and rotating the take-up roll 16 in the direction of arrow Z, the heat conduction sheet 2 arranged on the carrier film 3 is conveyed to the region facing the press 14.

[0114] After the heat conduction sheet 2 disposed on the carrier film 3 is conveyed to the region facing the press 14, the heat conduction sheet 2 is pressed in the direction of arrow Y using the press 14 with the heat conduction sheet 2 disposed between the press 14 and the semiconductor chip 13 disposed on the substrate 12, thereby crimping the heat conduction sheet 2 to the semiconductor chip 13. Note that, as shown in FIG. 3, the present invention is not limited to a configuration in which one heat conduction sheet 2 is crimped to one semiconductor chip 13, and a plurality of heat conduction sheets 2 may be crimped to one semiconductor chip 13, or one or a plurality of heat conduction sheets 2 may be crimped to each of a plurality of semiconductor chips 13.

[0115] After the heat conduction sheet 2 is crimped, the feeding roll 11 and the winding roll 16 are rotated to peel the carrier film 3 from the heat conduction sheet 2 crimped to the surface of the semiconductor chip 13 in the region 15. At this time, the carrier film 3 is peeled from the heat conduction sheet 2 via a release layer (not shown), the carrier film 3 with the release layer is collected by the winding roll 16, and a substrate with a semiconductor chip to which the heat conduction sheet 2 is crimped is obtained.

[0116] Then, the next heat conduction sheet 2 conveyed by the carrier film 3 is crimped to the surface of the semiconductor chip 13 disposed on the next substrate with a semiconductor chip, and the above-described steps are repeated to continuously mount the heat conduction sheet 2 on the substrate with a semiconductor chip. As described above, the heat conduction sheet can be efficiently crimped to the heating element.

Example

[0117] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” is based on mass.

[0118] [Example 1] When the compression stress at 150°C is 0.10 MPa, the compression modulus is 1.16 MPa, the tack force at 25°C is 7.6 N·mm, and the thermal conductivity is 16 W / (m·K). A plurality of thermal conductive sheets with a thickness of 150 μm, a longitudinal length of 30 mm in the carrier film, and a widthwise length of 50 mm, manufactured by Showa Denko Materials Co., Ltd., were prepared. In this thermal conductive sheet, flaky expanded graphite particles (Showa Denko Materials Co., Ltd. "HGF-L", mass average particle diameter: 270 μm) were used as the thermal conductive filler. By the method using the above-mentioned X-ray diffraction measurement, it was confirmed that the six-membered ring planes in the crystal were oriented in the plane direction of the flaky particles). Furthermore, a long carrier film and a long cover film shown below were prepared. Also, the following adhesive layer and release film provided between the carrier film and the thermal conductive sheet were prepared. (Carrier film) Long PET film: Trade name Lumirror S30 of Toray Industries, Inc., thickness 75 μm, widthwise length 66 mm (Cover film) Long paper film: A laminate of silicone release agent / polyethylene / craft paper, trade name SL-70S(U2) of Sumika Chemical Coated Papers, Ltd., total thickness 105 μm, widthwise length 66 mm, peel force with respect to the thermal conductive sheet 0 mN / 25 mm. Here, the peel force of 0 mN / 25 mm means that when the cover film is attached to a tensile testing machine so as to pull in a direction perpendicular to the interface with the thermal conductive sheet, it indicates that it has already peeled off. (Adhesive layer) Double-sided tape made of acrylic resin: Trade name Neo Fix30 of Nichiei Shinwa Co., Ltd., thickness 30 μm, widthwise length 50 mm (Release film) PET film treated with a release treatment agent: Trade name FU of Nippa Co., Ltd., thickness 75 μm, widthwise length 50 mm, peel force with respect to the thermal conductive sheet 18 mN / 25 mm

[0119] A plurality of sprocket holes with a diameter of approximately 2.0 mm were provided at regular intervals along the longitudinal direction at both ends in the width direction of the long carrier film, with a center-to-center distance of approximately 5.0 mm and a shortest distance of approximately 3.0 mm between the center of the sprocket hole and the end in the width direction of the carrier film. Further, for the carrier film, an adhesive layer and a release film were arranged in this order between both ends where the sprocket holes were provided along the longitudinal direction. At this time, the release film was arranged so that the surface treated with the release treatment agent of the release film was on the side opposite to the adhesive layer.

[0120] Six heat conduction sheets were arranged on one release film at a time so that both ends in the width direction of the release film and both ends in the width direction of the heat conduction sheet coincided, and a plurality of release films with six heat conduction sheets arranged thereon were arrayed along the longitudinal direction. At this time, the shortest distance between adjacent heat conduction sheets was adjusted to 20 mm.

[0121] Next, the plurality of heat conduction sheets were sandwiched between the cover film and the carrier film with both ends in the width direction of the carrier film and both ends in the width direction of the cover film being arranged to coincide in plan view, and the plurality of heat conduction sheets were attached to the cover film and the carrier film. Thereby, a long heat conduction sheet holder including a long carrier film, an adhesive layer, a release film, a plurality of heat conduction sheets, and a long cover film in this order was manufactured. The long heat conduction sheet holder was wound around a core along the longitudinal direction so that the carrier film side was located on the core side to obtain a roll-shaped heat conduction sheet holder. When using the roll-shaped heat conduction sheet holder in the roll-to-roll continuous process shown in Figure 3, it is necessary to pull out the heat conduction sheet holder and attach it to the take-up roll before starting the crimping process. In order not to generate a heat conduction sheet that cannot be used in the crimping process, no heat conduction sheet was provided between the cover film and the carrier film in a region of approximately 1 m in length that was first pulled out from the roll-shaped heat conduction sheet holder.

[0122] As shown in FIG. 3, a roll-shaped heat conduction sheet holder was attached to a pay-out roll, and while peeling off a cover film from the heat conduction sheet holder pulled out from the pay-out roll, the cover film was peeled off, and a carrier film in a portion where no heat conduction sheet was provided was attached to a take-up roll. The pay-out roll and the take-up roll were rotated to continuously convey a plurality of heat conduction sheets on the carrier film. Using a press machine disposed between the pay-out roll and the take-up roll in the conveyance direction of the heat conduction sheet, a heat conduction sheet was pressure-bonded to the surface of a semiconductor chip disposed on a substrate with a semiconductor chip under the conditions of 25° C. and 0.8 MPa. After the pressure bonding, the take-up roll was rotated to peel off the carrier film from the heat conduction sheet pressure-bonded to the surface of the semiconductor chip, and a substrate with a semiconductor chip to which the heat conduction sheet was pressure-bonded was recovered. Then, the next heat conduction sheet conveyed by the carrier film was pressure-bonded to the surface of a semiconductor chip disposed on the next substrate with a semiconductor chip, and by repeating the above-described steps, the heat conduction sheet could be continuously mounted on the substrate with a semiconductor chip. Further, in the present embodiment, when the cover film was peeled off from the heat conduction sheet via a release layer, the heat conduction sheet was not peeled off from the carrier film side and transferred to the cover film side, and displacement of the attachment position to the semiconductor chip caused by the heat conduction sheet being peeled off from the carrier film side was also suppressed. There was no transfer to the cover film side, and displacement of the attachment position to the semiconductor chip caused by the heat conduction sheet being peeled off from the carrier film side was also suppressed.

[0123] [Example 2] A long heat conduction sheet holder was manufactured in the same manner as in Example 1, except that the release film was changed from the product name FU of Nippa Co., Ltd. to the product name X1-A3 (thickness: 75 μm, length in the width direction: 50 mm, release force with respect to the heat conduction sheet: 38 mN / 25 mm) of Nippa Co., Ltd.

[0124] Regarding the heat conduction sheet holder manufactured in Example 2, a heat conduction sheet was pressure-bonded to a substrate with a semiconductor chip in the same manner as in Example 1. When peeling off the carrier film from the heat conduction sheet pressure-bonded to the surface of the semiconductor chip after the pressure bonding, it was more difficult to peel off the carrier film from the heat conduction sheet than in Example 1, and the heat conduction sheet was likely to be damaged.

[0125] [Example 3] A long strip-shaped heat conduction sheet holder was manufactured in the same manner as in Example 1, except that the release film in Example 1 was changed from the product name FU of Nippa Co., Ltd. to the product name 75E-0010 of Fujimori Kogyo Co., Ltd. (thickness: 75 μm, length in the width direction: 50 mm, peeling force with respect to the heat conduction sheet: 50 mN / 25 mm).

[0126] Regarding the heat conduction sheet holder manufactured in Example 3, a heat conduction sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling the carrier film from the heat conduction sheet pressure-bonded to the surface of the semiconductor chip after pressure-bonding, it was more difficult to peel the carrier film from the heat conduction sheet than in Example 2, and the heat conduction sheet was easily damaged.

[0127] [Example 4] A long strip-shaped heat conduction sheet holder was manufactured in the same manner as in Example 1, except that the cover film in Example 1 was changed from the product name SL-70S(U2) of Sumika Chemical Fibre Co., Ltd. to the product name FU of Nippa Co., Ltd. (thickness: 75 μm, length in the width direction: 66 mm, peeling force with respect to the heat conduction sheet: 18 mN / 25 mm).

[0128] Regarding the heat conduction sheet holder manufactured in Example 4, a heat conduction sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling the cover film, a part of the heat conduction sheet was more likely to stick to the cover film side than in Example 1, and the heat conduction sheet was easily damaged.

[0129] [Example 5] A long strip-shaped heat conduction sheet holder was manufactured in the same manner as in Example 1, except that the cover film in Example 1 was changed from the product name SL-70S(U2) of Sumika Chemical Fibre Co., Ltd. to the product name SP-8LK of Lintec Corporation (thickness: 88 μm, length in the width direction: 66 mm, peeling force with respect to the heat conduction sheet: 8 mN / 25 mm).

[0130] Regarding the heat conduction sheet holder manufactured in Example 5, a heat conduction sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling the cover film, a part of the heat conduction sheet was more likely to stick to the cover film side than in Example 1, and the heat conduction sheet was easily damaged.

[0131] [Example 6] In Example 4, the release film was changed from the product name FU of Nippa Co., Ltd. to the product name 75E-0010 of Fujimori Kogyo Co., Ltd. (thickness 75 μm, length in the width direction 50 mm, peeling force for the heat conduction sheet 50 mN / 25 mm), and a long heat conduction sheet holder was manufactured in the same manner as in Example 4 except for this change.

[0132] Regarding the heat conduction sheet holder manufactured in Example 6, a heat conduction sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling the cover film, a part of the heat conduction sheet was more likely to stick to the cover film side than in Example 1, and the heat conduction sheet was easily damaged.

[0133] The disclosure of PCT / JP2020 / 039140 filed on October 16, 2020 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Explanation of Reference Numerals

[0134] 1 Cover film 2 Heat conduction sheet 3 Carrier film 4 Release film 5 Adhesive layer 6 Core 7 Sprocket hole 10 Heat conduction sheet holder 11 Pay-out roll 12 Substrate 13 Heating element 14 Press 15 area 16 take-up roll

Claims

1. A long carrier film, a plurality of heat conduction sheets, and a long cover film covering the plurality of heat conduction sheets, provided in this order, The shortest distance between adjacent heat conduction sheets is 2 mm or more, The plurality of heat conduction sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of heat conduction sheets are peelable from the cover film, The carrier film and the plurality of heat conduction sheets further include a release layer therebetween, and the plurality of heat conduction sheets are peelable from the carrier film through the release layer, A plurality of the release layers arranged along the longitudinal direction of the carrier film, One or more of the heat conduction sheets are arranged on each of the plurality of release layers, When the cover film is arranged on the lower side in the vertical direction and the carrier film is arranged on the upper side in the vertical direction, the shape of the gap formed by the adjacent release layers and the adjacent heat conduction sheets arranged on the adjacent release layers respectively is convex when viewed from the width direction of the heat conduction sheet holder. A heat conduction sheet holder.

2. The heat conduction sheet holder according to claim 1, wherein the peeling force between the carrier film and the heat conduction sheet is greater than the peeling force between the cover film and the heat conduction sheet.

3. The heat conduction sheet holder according to claim 1 or claim 2, wherein the average thickness of the heat conduction sheet is 50 μm to 500 μm.

4. The heat conduction sheet holder according to any one of claims 1 to 3, wherein the heat conduction sheet contains a heat conduction filler and a resin.

5. The heat conduction sheet holder according to any one of claims 1 to 4, which is wound in a roll shape along the longitudinal direction.

6. The heat conduction sheet holder according to any one of claims 1 to 5, wherein in the width direction orthogonal to the longitudinal direction of the carrier film and the cover film, the width of the carrier film and the width of the cover film are larger than the width of the heat conduction sheet.

7. A method for manufacturing a heat dissipation device, wherein the heat conduction sheet is interposed between a heat generating body and a heat dissipating body by using the heat conduction sheet holder according to any one of claims 1 to 6, A step of peeling the cover film from the heat conduction sheet holder, In the heat conduction sheet holder from which the cover film has been peeled off, a step of pressing the heat conduction sheet onto one of the heating element and the heat dissipation element; A step of peeling the carrier film from the heat conduction sheet to which one of the heating element and the heat dissipation element is adhered; A step of pressing the other of the heating element and the heat dissipation element onto the side of the heat conduction sheet opposite to the side to which one of the heating element and the heat dissipation element is adhered; A method for manufacturing a heat dissipation device comprising the above steps.

Images