Method for manufacturing a heat conduction sheet holder and a heat dissipation device

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 thermally conductive sheet holder and a heat dissipation device. [Background technology]

[0002] In recent years, the amount of heat generated has increased due to the increasing density of wiring and electronic components in semiconductor packages using multilayer wiring boards, and the amount of heat generated per unit area has increased due to the high integration of semiconductor elements, making it desirable to improve the heat dissipation from semiconductor packages.

[0003] A heat dissipation device is generally used simply and easily, in which heat is dissipated by sandwiching a thermally conductive grease or a thermally conductive sheet between a heat generating body such as a semiconductor package and a heat sink such as aluminum or copper. In general, a thermally conductive sheet is easier to assemble than a thermally conductive grease.

[0004] Resin sheets filled with thermally conductive fillers are known as thermally conductive sheets. Various resin sheets filled with thermally conductive fillers and excellent in thermal conductivity have been proposed, in which inorganic particles with high thermal conductivity are selected as the thermally conductive filler and the inorganic particles are further oriented perpendicular to the sheet surface. For example, a thermally conductive sheet in which thermally conductive filler (boron nitride) is oriented in a direction approximately perpendicular to the sheet surface (see, for example, Patent Document 1), and a thermally conductive sheet in which carbon fibers dispersed in a gel-like 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] JP 2002-26202 A [Patent Document 2] JP 2001-250894 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is possible to manufacture a heat dissipation device by sandwiching and adhering the thermally conductive sheets described in Patent Documents 1 and 2 between a heating element such as a semiconductor package and a heat sink such as aluminum or copper. However, as demand for heat dissipation devices is increasing, there is a need for a method for efficiently manufacturing heat dissipation devices and thermally conductive sheets for use in such methods.

[0007] The present disclosure has been made in consideration of the above, and aims to provide a thermally conductive sheet holder that enables efficient manufacture of a heat dissipation device, and a method for manufacturing a heat dissipation device using this thermally conductive sheet holder. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects. <1> A thermally conductive sheet holder comprising, in this order, a long carrier film, a plurality of thermally conductive sheets, and a long cover film covering the plurality of thermally conductive sheets, the plurality of thermally conductive sheets being arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of thermally conductive sheets being peelable from the cover film and the carrier film. <2> A release layer is further provided between the carrier film and the plurality of thermally conductive sheets, and the plurality of thermally conductive sheets are peelable from the carrier film via the release layer. <1> The thermal conductive sheet holder according to claim 1. <3> The carrier film has a plurality of release layers arranged along a longitudinal direction thereof, and one or more of the thermally conductive sheets are arranged on each of the plurality of release layers. <2> The thermal conductive sheet holder according to claim 1. <4> When the cover film is disposed so that it is on the lower side in the vertical direction and the carrier film is disposed so that it is on the upper side in the vertical direction, the shape of the gap formed by the adjacent release layers and the adjacent thermally conductive sheets disposed on the adjacent release layers respectively is a convex shape when viewed from the width direction of the thermally conductive sheet holder. <3> The thermal conductive sheet holder according to claim 1. <5> The peeling force between the carrier film and the thermally conductive sheet is greater than the peeling force between the cover film and the thermally conductive sheet. <1> ~ <4> 13. The thermal conductive sheet holder according to claim 12 . <6> The average thickness of the thermally conductive sheet is 50 μm to 500 μm. <1> ~ <5> 13. The thermal conductive sheet holder according to claim 12 . <7> The thermally conductive sheet contains a thermally conductive filler and a resin. <1> ~ <6> 13. The thermal conductive sheet holder according to claim 12 . <8> It is wound in a roll along its length. <1> ~ <7> 13. The thermal conductive sheet holder according to claim 12 . <9> In a width direction perpendicular to a 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 thermally conductive sheet. <1> ~ <8> 13. The thermal conductive sheet holder according to claim 12 . <10> The shortest distance between adjacent heat conductive sheets is 2 mm or more. <1> ~ <9> 13. The thermal conductive sheet holder according to claim 12 . <11> No cuts are formed on the surface of the carrier film <1> ~ <10> 13. The thermal conductive sheet holder according to claim 12 .

[0009] <12> <1> ~ <11> 13. A method for manufacturing a heat dissipation device, comprising the steps of: using the heat conduction sheet holder described in any one of claims 1 to 12 to manufacture a heat dissipation device having the heat conduction sheet interposed between a heat generating element and a heat dissipation element; peeling off the cover film from the heat conduction sheet holder; pressing the heat conduction sheet to one of the heat generating element and the heat dissipation element in the heat conduction sheet holder from which the cover film has been peeled off; peeling off the carrier film from the heat conduction sheet to which one of the heat generating element and the heat dissipation element is adhered; and pressing the other of the heat generating element and the heat dissipation element to the side of the heat conduction sheet opposite to the side to which the one of the heat generating element and the heat dissipation element is adhered. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a heat conductive sheet holder that enables efficient production of a heat dissipation device, and a method for producing a heat dissipation device using this heat conductive sheet holder. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a side view showing an example of a thermally conductive sheet holder of the present disclosure. [Diagram 2] FIG. 2 is a diagram of an area α corresponding to the dotted line in FIG. 1 as viewed from the cover film 1 side. [Diagram 3] FIG. 3 is a schematic diagram showing a part of a manufacturing process in an example of a method for manufacturing a heat dissipation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiment for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiment. In the following embodiment, the components (including element steps, etc.) are not essential unless specifically stated. The same applies to the numerical values ​​and their ranges, and they do not limit the present invention. In the present disclosure, the term "step" includes not only a step that is 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 present disclosure, a numerical range indicated using "~" includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples. In the present disclosure, when a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total content of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, multiple types of particles corresponding to each component may be included. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where the layer is formed over the entire area when the area in which the layer exists is observed, as well as cases where the layer is formed over only a portion of the area. In this disclosure, the term "lamination" refers to stacking layers, where two or more layers may be bonded together or two or more layers may be removable. In the present disclosure, the thickness of a layer is determined by measuring the thickness of the layer at five points and calculating the arithmetic mean value. The thickness of a layer can be measured using a micrometer or the like. In the present disclosure, when the thickness of a layer can be measured directly, it is measured using a micrometer. On the other hand, when the thickness of one layer or the total thickness of multiple layers is measured, it may be measured by observing the cross section of the measurement target using an electron microscope. When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0013] <Heat conductive sheet holder> The thermally conductive sheet holder of the present disclosure comprises, in this order, a long carrier film, a plurality of thermally conductive sheets, and a long cover film covering the plurality of thermally conductive sheets, the plurality of thermally conductive sheets being arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of thermally conductive sheets being peelable from the cover film and the carrier film.

[0014] In the thermally conductive sheet holder of the present disclosure, multiple thermally conductive sheets are arranged on a long carrier film, and the multiple thermally conductive sheets can be transported together with the carrier film. This allows the multiple thermally conductive sheets, the cover films of which have been peeled off from the thermally conductive sheet holder, to be transported together with the carrier film and attached to a heat generating body, a heat sink, or the like, so that the thermally conductive sheets can be continuously mounted on the heat generating body, the heat sink, or the like. As a result, it is possible to efficiently manufacture a heat dissipation device.

[0015] The thermally conductive sheet holder of the present disclosure is preferably configured to be wound into a roll along the longitudinal direction. In this case, the thermally conductive sheet holder may be wound around a winding core. By pulling out the thermally conductive sheet holder wound into a roll and peeling off the cover film from the thermally conductive sheet, it becomes possible to continuously mount the thermally conductive sheet on a heating element, a heat sink, etc. in a roll-to-roll continuous process, and the heat dissipation device can be manufactured more efficiently.

[0016] (Carrier film) The thermally conductive sheet holder of the present disclosure includes a long carrier film. The carrier film is a long film member for transporting a thermally conductive sheet, and a plurality of thermally conductive sheets are arranged at intervals along the longitudinal direction on the carrier film, either directly or via a release layer or the like described below. The carrier film is peelable from the thermally conductive sheet.

[0017] The material of the carrier film is not particularly limited as long as it is capable of transporting multiple thermally conductive sheets arranged on the carrier film directly or via a release layer, etc., and examples of the material 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 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 off the carrier film from the thermally conductive sheet, a release layer may be provided between the carrier film and the multiple thermally conductive sheets, and the carrier film may be peelable from the multiple thermally conductive 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 carrier film described above. In addition, the release layer such as a release film may be provided on the carrier film via an adhesive layer, and in the thermally conductive sheet holder of the present disclosure, the carrier film, the adhesive layer, the release layer, and the thermally conductive 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, transportability of the thermal conductive 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 further preferably 50 μm to 100 μm.

[0021] When a release layer is provided between the carrier film and the multiple thermally conductive sheets, the average thickness of the release layer is not particularly limited, and from the viewpoint of the releasability of the thermally conductive sheets and the miniaturization of the thermally conductive 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 surface-treated with a release agent, the average thickness of the release film is not particularly limited, and from the viewpoint of ensuring adhesive properties and reducing the size of the thermal conductive 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 in the adhesive layer include commonly 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, a tackifier, etc. The average thickness of the adhesive layer is not particularly limited, and from the viewpoint of ensuring adhesive properties and reducing the size of the thermally conductive 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 thermally conductive 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 thermally conductive sheets. The cover film is peelable from the thermally conductive sheets.

[0024] The cover film is not particularly limited, and examples thereof include the above-mentioned resin films that can be included in the carrier film, paper films such as fine paper, coated paper, craft paper, glassine paper, and recycled paper, and metal foils such as aluminum. Among these, paper films are preferred from the viewpoint of easily peeling the cover film from the thermal conductive sheet. The cover film may be a single layer film made of any one of the above-mentioned films, metal foils, etc., or a multilayer film in which two or more of the above-mentioned films, metal foils, etc. are laminated.

[0025] In addition, a release layer may be provided on the surface of the cover film facing the multiple thermally conductive sheets, and the cover film may be peelable from the multiple thermally conductive sheets via the release layer. The release layer may be, for example, a layer containing a silicone-based, silica-based or other release agent. When the cover film is a paper film, a layer containing polyethylene or the like that functions as a sealant may be disposed between the layer containing the release agent and the paper film in order to prevent the release agent from penetrating into the paper film.

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

[0027] In the thermally conductive sheet holder of the present disclosure, it is preferable that no notches are generated on the surface of the cover film, carrier film or release film, preferably on the surface on the thermally conductive sheet side, and more preferably that no notches are generated due to cutting by dicing processing, laser processing, or the like. In particular, it is preferable that no notches are generated on the surface of the cover film or carrier film, and more preferably that no notches are generated on the surface of the carrier film. When no notches are generated on these films, when tensile stress or the like is applied to the thermally conductive sheet holder, these films are prevented from breaking or deforming. As a result, problems such as the inability to continuously press the thermally conductive sheet to the adherend using the thermally conductive sheet holder, the relative positions between the multiple thermally conductive sheets shifted in the thermally conductive sheet holder, and the inability to press the thermally conductive sheet to the adherend with precision are prevented from occurring. In particular, since no notches are generated in the carrier film, even when the thermally conductive sheet is pressed to 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, positional deviation of the thermally conductive sheet on the carrier film, etc. are suitably suppressed.

[0028] In the thermally conductive sheet holder of the present disclosure, it is preferable that the peeling force between the carrier film and the thermally conductive sheet is greater than the peeling force between the cover film and the thermally conductive sheet, which makes it possible to suppress peeling between the carrier film and the thermally conductive sheet when the cover film is peeled off from the thermally conductive sheet holder, and to suppress the thermally conductive sheet from adhering to the peeled cover film.

[0029] For example, the peel force between the cover film and the thermally conductive sheet and the peel force between the carrier film and the thermally conductive sheet may be adjusted by providing a release layer between the carrier film and the multiple thermally conductive sheets, by providing a release layer on the surface of the cover film facing the multiple thermally conductive sheets, or by changing the type of release agent contained in these release layers.

[0030] When a release layer is provided between the carrier film and the multiple thermally conductive sheets, it is preferable that the peel force between the release layer and the thermally conductive sheets is greater than the peel force between the cover film and the thermally conductive sheets.

[0031] The peel strength between the cover film and the thermal conductive 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 strength of 0 mN / 25 mm indicates that the cover film is already peeled off when the cover film is attached to a tensile tester so as to be pulled in a direction at 90° to the interface with the thermal conductive sheet. The peel force between the cover film and the thermally conductive sheet of the present disclosure is the maximum peel strength measured when a laminate film with a width of 25 mm is prepared and the cover film is pulled at 90° to the interface with the thermally conductive sheet using a tensile tester at a tensile speed of 100 mm / min and a temperature of 23°C to peel the cover film from the thermally conductive sheet.

[0032] The peel force between the carrier film and the thermally conductive sheet, preferably between the release layer disposed between the carrier film and the thermally conductive sheet and the thermally conductive 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 release layer and the thermally conductive sheet of the present disclosure is the maximum peel strength when a laminate film with a width of 25 mm is prepared and the carrier film or release layer is pulled at 90° to the interface with the thermally conductive sheet using a tensile tester at a tensile speed of 100 mm / min and a temperature of 23°C to peel the carrier film or release layer from the thermally conductive sheet.

[0033] The peel force between the carrier film and the thermally conductive sheet (preferably the peel force between the release layer disposed between the carrier film and the thermally conductive sheet and the thermally conductive sheet) is preferably greater than the peel force between the cover film and the thermally conductive sheet, and the difference therebetween 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] From the viewpoint of adhesion to the adherend, the sheet-like material such as the thermal conductive sheet may have an adhesive component on the surface facing the cover film. In the sheet-like material holder, the sheet-like material is held in a state where the cover film is not in contact with the sheet-like material, so that adhesion of the sheet-like material to the cover film due to the adhesive component is suppressed.

[0035] (Thermal Conduction Sheet) The thermally conductive sheet holder of the present disclosure comprises a plurality of thermally conductive sheets between a long carrier film and a long cover film, and the plurality of thermally conductive sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film.

[0036] The average thickness of the thermally conductive sheet is not particularly limited and can be appropriately selected depending on the purpose. Specifically, the average thickness of the thermally conductive 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 thermally conductive sheet is not particularly limited and may be appropriately changed depending on the shapes of the heating element and the heat dissipating element to which the thermally conductive sheet is adhered. The shape of the main surface of the thermally conductive sheet may be circular, elliptical, polygonal, etc.

[0038] When the main surface of the thermally conductive sheet has a polygonal shape, preferably a quadrangular shape such as a rectangle, the length of one side may be 3 mm to 100 mm, or 5 mm to 80 mm.

[0039] When the main surface of the thermally conductive sheet is rectangular, it is preferable that the multiple thermally conductive sheets are arranged so that two opposing sides of the main surface are aligned along the longitudinal direction of the carrier film. In this case, the ratio (width direction length / longitudinal length) of the length of the two sides along the longitudinal direction of the carrier film (longitudinal length) to the length of the two sides along the width direction perpendicular to the longitudinal direction of the carrier film (width direction length) may be 0.1 to 5, 0.2 to 4, or 0.3 to 3.

[0040] For a plurality of thermally conductive sheets arranged at intervals in the longitudinal direction of the carrier film and the cover film, the shortest distance between adjacent thermally conductive sheets may be 2 mm or more, 2 mm to 100 mm, 5 mm to 60 mm, or 5 mm to 30 mm. By making the shortest distance between adjacent thermally conductive sheets 2 mm or more, when the thermally conductive sheet is pressure-bonded to an adherend such as a heating body or a heat dissipating body, it is possible to suppress interference of another thermally conductive sheet adjacent to the thermally conductive sheet to be pressure-bonded to the adherend. This tends to suppress damage to another thermally conductive sheet, unintended adhesion of another thermally conductive sheet to the adherend, etc. In addition, by making the shortest distance between adjacent thermally conductive sheets 100 mm or less, there is a tendency for productivity to be excellent when pressure-bonding the thermally conductive sheet to an adherend such as a heating body or a heat dissipating body.

[0041] The thermally conductive sheet holder of the present disclosure may include a plurality of release layers disposed along the longitudinal direction of the carrier film between the carrier film and the plurality of thermally conductive sheets, and one or more thermally conductive sheets may be disposed on each of the plurality of release layers. Also, two or more thermally conductive sheets may be disposed on each of the plurality of release layers, and 2 to 50 thermally conductive sheets may be disposed. By disposing a plurality of release layers, it tends to be possible to suppress warping of the release layers, positional deviation of the thermally conductive sheets due to warping, and the like.

[0042] Furthermore, when the thermally conductive sheet holder of the present disclosure is arranged so that the cover film is on the vertical lower side and the carrier film is on the vertical upper side, it is preferable that the shape of the gap formed by adjacent release layers and adjacent thermally conductive sheets arranged on the adjacent release layers is a convex shape when viewed in the width direction of the thermally conductive sheet holder. This means that no thermally conductive sheet is arranged at both ends in the longitudinal direction on the surface on which the thermally conductive sheets of the multiple release layers are arranged, and this tends to make it easier to peel the carrier film from the thermally conductive sheet.

[0043] When the shape of the aforementioned gap is convex when viewed from the width direction of the thermal conductive sheet holder, the ratio of the vertical upper side of the convex shape, which is the shortest distance between adjacent release layers, to the vertical lower side of the convex shape, which is the shortest distance between adjacent thermal conductive sheets (vertical lower side of the convex shape / vertical upper side of the convex shape) may be greater than 1 and not greater than 300, may be 1.2 to 50, or may be 1.5 to 10.

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

[0045] The width direction length of the carrier film and the width direction length of the cover film are preferably greater than the width direction length of the thermally conductive sheet. When the width direction length of the carrier film is greater than the width direction length of the thermally conductive sheet, the carrier film can be easily transported and the carrier film can be easily peeled off from the thermally conductive sheet. When the width direction length of the cover film is greater than the width direction length of the thermally conductive sheet, the thermally conductive sheet can be suitably protected and the cover film can be easily peeled off from the thermally conductive sheet.

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

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

[0048] From the viewpoint of transportability, the thermally conductive sheet holder of the present disclosure is preferably such that no thermally conductive sheet is disposed at both ends of the carrier film in the width direction, and more preferably such that 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 thermally conductive sheets at regular intervals along the longitudinal direction of the carrier film based on the intervals between the sprocket holes, and it also becomes easy to position the thermally conductive sheet when it is pressed against one of the heating element and the heat sink.

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

[0050] In the heat conductive sheet used in the present disclosure, from the viewpoint that the heat conductive sheet is easily crushed under the high temperature pressing conditions in the second pressure bonding step described later and is easily adhered to the other of the heat generating body and the heat dissipating body, the compressive elastic modulus when the compressive 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 compressive elastic modulus when the compressive stress at 150°C is 0.1 MPa is not particularly limited. The compressive elastic modulus may be 0.5 MPa or more, or may be 0.7 MPa or more.

[0051] The compressive elastic modulus of the thermal conductive sheet can be measured using a compression test device (e.g., INSTRON 5948 Micro Tester (INSTRON)). A load is applied to the thermal conductive sheet in the thickness direction, and the displacement (mm) and load (N) are measured. The horizontal axis represents the strain (dimensionless) calculated by displacement (mm) / thickness (mm), while the horizontal axis represents load (N) / area (mm 2 The stress (MPa) obtained by the above equation is plotted on the vertical axis, and the slope at a given stress is the compressive modulus (MPa). Specifically, it can be measured, for example, by the method described in the Examples.

[0052] In the thermally conductive sheet used in the present disclosure, the tack strength 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. If the tack strength is 5.0 N·mm or more, when a heat dissipation device including the thermally conductive sheet warps and the distance between the heat generating body and the heat dissipation body increases, the thermally conductive sheet can be prevented from peeling off from the heat generating body and the heat dissipation body. There is no particular upper limit to the tack strength. The tack strength may be 20.0 N·mm or less, or 15.0 N·mm or less.

[0053] The tack strength of a thermal conductive sheet at 25°C can be measured using a universal property testing machine (for example, a Texture Analyzer (Eiko Seiki Co., Ltd.)). At 25°C (room temperature), a 7mm diameter probe is pressed against the thermal conductive sheet with a load of 40N and held there for 10 seconds, and then the probe is lifted up. The area obtained by integrating the load and displacement curve is the tack strength (N mm) at 25°C.

[0054] The thermally conductive sheet used in the present disclosure preferably satisfies the above-mentioned conditions for both the compressive elastic modulus when the compressive stress at 150°C is 0.1 MPa and the tack strength at 25°C.

[0055] As mentioned above, a thermally conductive sheet with a compressive modulus of 1.4 MPa or less when the compressive stress at 150°C is 0.1 MPa is a soft sheet, and a thermally conductive sheet with a tack force of 5.0 N·mm or more at 25°C is a highly adhesive sheet. Therefore, when attempting to pick up such a soft or highly adhesive thermally conductive sheet and mount it on a heating body, heat sink, etc., there is a problem that the soft or highly adhesive thermally conductive sheet itself is easily deformed or broken, and the soft or highly adhesive thermally conductive sheet cannot be easily peeled off from the base material such as a protective sheet, or the thermally conductive sheet itself is deformed or broken after peeling, making it impossible to use it for mounting on a heating body, heat sink, etc.

[0056] On the other hand, with the thermally conductive sheet holder disclosed herein, no pick-up as described above is required when mounting the thermally conductive sheet on a heating element, heat sink, etc., and the thermally conductive sheet can be continuously mounted on a heating element, heat sink, etc. while suppressing deformation, breakage, etc. of the thermally conductive sheet itself, resulting in excellent handleability of the thermally conductive sheet and excellent manufacturing efficiency for the heat dissipation device.

[0057] The above compressive elastic modulus and tack strength can be obtained, for example, by adjusting the blending ratio of each component used in the thermally conductive sheet. A preferred composition of the thermally conductive sheet will now be described.

[0058] <Heat conductive filler> The thermally conductive sheet preferably contains a thermally conductive filler. The thermally conductive filler is not particularly limited as long as it is a filler having thermal conductivity. Examples of the thermally conductive filler include particles of highly thermally conductive 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 thermally conductive filler, one type may be used alone, or two or more types may be used in combination.

[0059] As the thermally conductive filler, graphite particles are preferred, particularly from the viewpoint of low thermal resistance and excellent thermal conductivity, and at least one type of graphite particles selected from the group consisting of scale-like particles, ellipsoidal particles, and rod-like particles, which will be described later, is more preferred.

[0060] The mass average particle size (D50) of the thermal conductive filler is measured using a laser diffraction particle size distribution device (e.g., "Microtrac Series MT3300" manufactured by Nikkiso Co., Ltd.) that applies the laser diffraction / scattering method, and corresponds to the particle size at which the weight accumulation becomes 50% when the weight accumulation particle size distribution curve is plotted from the small particle size side.

[0061] The particle size distribution of the thermally conductive filler is not particularly limited, and may be a monodisperse system in which the particle size distribution, with the particle size on the horizontal axis and the frequency on the vertical axis, has a single peak, or a polydisperse system in which the particle size distribution has multiple peaks. In addition, the particle size distribution may be narrow or wide.

[0062] The content of the thermally conductive filler in the thermally conductive sheet is preferably 15 volume % to 50 volume %, more preferably 20 volume % to 45 volume %, and even more preferably 25 volume % to 40 volume %, from the viewpoint of the balance between thermal conductivity and adhesion to heat generating bodies, heat dissipating bodies, etc. When the content of the thermally conductive filler is 15% by volume or more, the thermal conductivity tends to be improved. When the content of the thermally conductive filler is 50% by volume or less, the decrease in adhesion to the heat generating body, heat dissipating body, etc. tends to be more effectively suppressed.

[0063] The content (volume %) of the thermally conductive filler is a value calculated by the following formula. Thermally conductive filler content (volume%) = (Aw / Ad) / ((Aw / Ad)+(Bw / Bd)+(Cw / Cd)) x 100 Aw: Mass composition of thermally conductive filler (mass%) Bw: Resin mass composition (mass%) Cw: Mass composition of other optional components (mass%) Ad: Density of thermally conductive filler Bd: Density of resin Cd: Density of any other component

[0064] The thermally conductive filler may contain at least one type of graphite particles selected from the group consisting of scaly particles, ellipsoidal particles, and rod-shaped particles. In addition, when the graphite particles are scaly particles, the planar direction may be oriented in the thickness direction, when the graphite particles are ellipsoidal particles, the major axis direction may be oriented in the thickness direction, or when the graphite particles are rod-shaped particles, the major axis direction may be oriented in the thickness direction. With this configuration, the thermally conductive sheet has 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 improved. This is because, for example, flaky graphite particles are more easily oriented in a predetermined direction in the thermal conductive sheet. The six-membered ring plane is a plane on which six-membered rings are formed in a hexagonal crystal system, and means a (0001) crystal plane.

[0066] Whether the hexagonal ring planes in the graphite particle crystals are oriented in the planar direction of the scaly particles, the long axis direction of the ellipsoidal particles, or the long axis direction of the rod-shaped particles can be confirmed by X-ray diffraction measurement. The orientation direction of the hexagonal ring planes in the graphite particle crystals is specifically confirmed by the following method.

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

[0068] A mixture of resin and graphite particles in an amount of 10% by volume or more relative 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 peaks that interfere with X-ray diffraction and can be formed into a sheet. Specifically, amorphous resins that have cohesive power as a binder, such as acrylic rubber, NBR (acrylonitrile butadiene rubber), and SIBS (styrene-isobutylene-styrene copolymer), can be used.

[0069] The mixture sheet is pressed to 1 / 10 or less of its original thickness, and multiple pressed sheets are stacked to form a laminate. This laminate is further crushed to 1 / 10 or less, and this operation is repeated three or more times to obtain a sample sheet for measurement. This operation results in the graphite particles in the sample sheet for measurement being oriented in the planar direction in the case of scaly 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, along the planar direction of the sample sheet for measurement.

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

[0071] From this, the phrase "the six-membered ring planes in the crystals of the graphite particles are oriented in the planar direction in the case of scaly particles, in the long axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-shaped particles" refers to a state in which, when X-ray diffraction measurement is performed on the surface of a sheet containing graphite particles, the height of the peak corresponding to the (110) plane of the graphite particles which appears around 2θ=77° divided by the height of the peak corresponding to the (002) plane of the graphite particles which appears around 2θ=27° yields a value between 0 and 0.02.

[0072] In the present disclosure, X-ray diffraction measurements are performed under the following conditions. Equipment: Bruker AXS "D8DISCOVER" X-ray source: CuKα with wavelength of 1.5406 nm, 40 kV, 40 mA Step (measurement increment): 0.01° Step time: 720sec

[0073] Here, "graphite particles are oriented in the planar direction in the case of scaly particles, in the major axis direction in the case of ellipsoidal particles, and in the thickness direction in the case of rod-shaped particles" means that the angle (hereinafter also referred to as "orientation angle") between the planar direction in the case of scaly 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 conductive sheet 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 of the angle (orientation angle) between the surface (main surface) of the thermal conductive sheet and the planar direction in the case of scaly particles, the long axis direction in the case of ellipsoidal particles, or the long axis direction in the case of rod-shaped particles, measured for 50 random 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 conductive sheet. When the average particle size of the graphite particles is 1 / 2 or more of the average thickness of the heat conductive sheet, an efficient heat conductive path is formed in the heat conductive sheet, and the thermal conductivity tends to be improved. When the average particle size of the graphite particles is equal to or less than the average thickness of the heat conductive sheet, the protrusion of the graphite particles from the surface of the heat conductive sheet is suppressed, and the surface of the heat conductive sheet tends to have excellent adhesion.

[0076] In addition, when using the laminated slice method as described in JP 2008-280496 A, the particle diameter of the graphite particles used as the raw material is preferably 1 / 2 or more times the average thickness of the heat conductive 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 the raw material may exceed the average thickness of the heat conductive sheet is, for example, that even if the graphite particles have a particle diameter exceeding the average thickness of the heat conductive sheet, the graphite particles are sliced ​​together to form the heat conductive sheet, so that the graphite particles do not protrude from the surface of the heat conductive sheet. In addition, when the graphite particles are sliced ​​together in this way, many graphite particles are generated that penetrate the heat conductive sheet in the thickness direction, and an extremely efficient heat conductive path is formed, which tends to further improve the heat conductivity.

[0077] When the laminate slice method is used, the particle diameter of the graphite particles used as the raw material is more preferably 1 to 5 times the average thickness of the heat conductive 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 conductive sheet, a more efficient heat conductive path is formed, and the heat conductivity is further improved. When it is 5 times or less the average thickness of the heat conductive sheet, the area of ​​the surface of the graphite particles is prevented from becoming too large, and a decrease in adhesion can be suppressed.

[0078] The content of graphite particles in the thermally conductive filler is, for example, preferably 50 volume% to 100 volume%, more preferably 80 volume% to 100 volume%, even more preferably 95 volume% to 100 volume%, and particularly preferably 100 volume%, relative to the total volume of the thermally conductive filler.

[0079] The thermally conductive sheet may contain graphite particles other than scaly particles, ellipsoidal particles, and rod-shaped particles, and may contain spherical graphite particles, artificial graphite particles, exfoliated graphite particles, acid-treated graphite particles, expanded graphite particles, carbon fiber flakes, etc. As the graphite particles, scaly particles are preferred, and from the viewpoint of high crystallinity and ease of obtaining large-diameter flakes, scaly expanded graphite particles obtained by pulverizing sheet-formed expanded graphite are preferred.

[0080] <Resin> The thermally conductive sheet preferably contains a resin. By containing a resin, the thermally conductive sheet tends to have excellent flexibility and good adhesion to a heat generating body, a heat dissipating body, and the like.

[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 resin content in the thermal conductive sheet is preferably selected depending on the type of resin and the desired flexibility, adhesive strength, adhesion, sheet strength, hydrolysis resistance, etc. For example, the resin content is preferably 25% to 75% by volume, more preferably 40% to 70% by volume, and even more preferably 50% to 65% by volume, relative to the total volume of the thermal conductive sheet.

[0083] <Other ingredients> The thermally conductive sheet may contain other components in addition to the thermally conductive filler and the resin depending on the purpose. For example, the thermally conductive 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 flame retardants and phosphate ester flame retardants can be mentioned. Among them, phosphate ester flame retardants are preferable because they are safe and have improved adhesion due to their plasticity effect.

[0085] As the red phosphorus-based flame retardant, in addition to pure red phosphorus powder, red phosphorus having various coatings for the purpose of improving safety or stability, master batches, etc., may be used. Specific examples include NOVA RED, NOVA EXCEL, NOVA QUEL, and NOVA PELLET (all trade names) manufactured by RIN KAGAKU KOGYO CO., LTD.

[0086] Examples of the phosphate ester-based flame retardants include 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; and aromatic condensed phosphate esters such as resorcinol bisdiphenyl phosphate, bisphenol A bis(diphenyl phosphate), and resorcinol bisdixylenyl phosphate. Among these, bisphenol A bis(diphenyl phosphate) is preferred because it has excellent hydrolysis resistance and is excellent in the effect of improving adhesion due to its plasticizing effect.

[0087] The content of the flame retardant in the thermal conductive sheet is not limited and can be used in an amount that exhibits flame retardancy; it is preferable to keep it at 40% by volume or less, and it is preferable to keep it at 30% by volume or less in order to prevent the deterioration of thermal resistance due to the flame retardant components seeping out to the surface of the thermal conductive sheet.

[0088] The thermal conductive sheet may contain additives such as antioxidants, radical traps, pH adjusters, etc., as necessary, and preferably contains antioxidants. The content of these additives in the thermal conductive sheet is preferably 5% by volume or less, more preferably 3% by volume or less, and even more preferably 1% by volume or less.

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

[0090] The thermally conductive sheet contained in the thermally conductive sheet holder produced by such a method is likely to form an efficient thermally conductive path, and therefore tends to have high thermal conductivity and excellent adhesion.

[0091] <Preparation process> The composition constituting the thermally conductive sheet may be prepared by any method, as long as it is possible to uniformly mix the thermally conductive filler, the resin, and other components as necessary, and is not particularly limited. The composition may also be prepared by purchasing a commercially available product. For details on the preparation of the composition, refer to paragraph

[0033] of JP 2008-280496 A.

[0092] <Sheet manufacturing process> The sheet preparation step may be any method that can form the composition obtained in the previous step into a sheet, and is not particularly limited. For example, it is preferable to carry out the sheet preparation step using at least one molding method selected from the group consisting of rolling, pressing, extrusion, and coating. For details of the sheet preparation step, refer to paragraph

[0034] of JP2008-280496A.

[0093] <Laminate manufacturing process> In the laminate preparation step, a laminate of the sheets obtained in the previous step is formed. The laminate is not limited to a form in which a plurality of independent sheets are stacked in order, but may be a form in which a single sheet is folded without being cut, or a single sheet is rolled up. For details of the laminate preparation step, refer to paragraphs

[0035] to

[0037] of JP2008-280496A.

[0094] <Slicing process> The slicing step may be any method that can slice the side end surface of the laminate obtained in the previous step, and is not particularly limited. From the viewpoint of forming an extremely efficient heat conduction path by the graphite particles penetrating the heat conductive sheet in the thickness direction and further improving the heat conductivity, it is preferable to slice the sheet to a thickness of not more than twice the mass average particle diameter of the graphite particles. For details of the slicing step, refer to paragraph

[0038] of JP 2008-280496 A.

[0095] <Lamination process> The lamination process may be any method, and is not particularly limited, as long as the sliced ​​thermally conductive sheets are sandwiched between a cover film and a carrier film or a cover film and a release film, and the thermally conductive sheets are attached to the cover film and the carrier film or the release film. For example, the sliced ​​thermally conductive sheets may be cut to a predetermined size, and then the thermally conductive sheets are arranged on the cover film, the carrier film or the release film, and then the arranged thermally conductive sheets are sandwiched between the cover film and the carrier film or the cover film and the release film, and the thermally conductive sheets are attached to them to obtain a thermally conductive sheet holder. In addition to the above method, for example, the sliced ​​thermally conductive sheets may be arranged on the cover film, the carrier film or the release film, and the thermally conductive sheets are cut to a predetermined size by punching or the like, and then the cut thermally conductive sheets are sandwiched between the cover film and the carrier film or the cover film and the release film, and the thermally conductive sheets are attached to them to obtain a thermally conductive sheet holder.

[0096] For example, in the lamination process, a long thermally conductive sheet is placed on a cover film, a carrier film, or a release film, and the long thermally conductive sheet is cut by dicing, laser processing, or the like, so that multiple thermally conductive sheets can be placed on the cover film, the carrier film, or the release film. However, when a long thermally conductive sheet is cut by dicing, laser processing, or the like, the cover film, the carrier film, or the release film on which the long thermally conductive sheet is placed may also be partially cut in the thickness direction, causing a notch. If a notch occurs on these films, these films may break or deform when tensile stress or the like is applied to the obtained thermally conductive sheet holder. As a result, problems such as the inability to continuously press the thermally conductive sheet onto the adherend using the thermally conductive sheet holder, the relative positions between the multiple thermally conductive sheets shifted by the thermally conductive sheet holder, and the inability to press the thermally conductive sheet onto the adherend with precision are likely to occur. In particular, such problems are likely to occur when a notch occurs in the cover film or the carrier film, and when a notch occurs in the carrier film, it becomes difficult to perform a continuous process using the method shown in FIG. 3, which will be described later.

[0097] From the above viewpoints, the lamination step preferably includes arranging a plurality of thermally conductive sheets on a cover film, a carrier film, or a release film, or cutting a thermally conductive sheet arranged on a cover film, a carrier film, or a release film by punching or the like. This prevents or suppresses the occurrence of cuts in the cover film, the carrier film, or the release film, and can suitably suppress breakage, deformation, etc. of the film when tensile stress, etc. is applied to the thermally conductive sheet holder. Furthermore, unlike the case where a long thermally conductive sheet is cut by dicing processing, laser processing, etc., it is also easy to arrange a plurality of thermally conductive sheets so that the shortest distance between adjacent thermally conductive sheets is 2 mm or more.

[0098] <Method of manufacturing heat dissipation device> The manufacturing method for a heat dissipation device of the present disclosure is a manufacturing method for a heat dissipation device that uses the heat conduction sheet holder of the present disclosure to manufacture a heat dissipation device having the heat conduction sheet interposed between a heating element and a heat sink, and includes the steps of peeling off the cover film from the heat conduction sheet holder, pressing the heat conduction sheet to one of the heating element and the heat sink on the heat conduction sheet holder from which the cover film has been peeled off, peeling the carrier film from the heat conduction sheet to which one of the heating element and the heat sink is adhered, and pressing the other of the heating element and the heat sink to the side of the heat conduction sheet opposite to the side to which the heating element and the heat sink are adhered.

[0099] In the heat dissipation device obtained by the manufacturing method of the present disclosure, the heat generating body and the heat dissipation body are laminated with the heat conductive sheet interposed therebetween, so that the heat from the heat generating body can be efficiently conducted to the heat dissipation body. Furthermore, the heat conductive sheet can be easily removed when removing the heat dissipation body from the heat generating body.

[0100] The manufacturing method of the present disclosure includes a step of peeling off the cover film from the thermally conductive sheet holder. For example, when the thermally conductive sheet holder of the present disclosure is wound in a roll, the cover film may be peeled off while the roll-shaped thermally conductive sheet holder is being unwound in a state where it is attached to a rotatable unwinding roll.

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

[0102] Examples of heat generating bodies include semiconductor packages in which semiconductor chips are arranged on a substrate, displays, LEDs, electric lights, automotive power modules, and industrial power modules. Examples of heat dissipating bodies include heat sinks using aluminum or copper fins, plates, etc., aluminum or copper blocks connected to heat pipes, aluminum or copper blocks in which cooling liquid is circulated by a pump, and Peltier elements and aluminum or copper blocks equipped with the same.

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

[0104] The manufacturing method of the present disclosure includes a step of peeling off the carrier film from the thermally conductive sheet to which one of the heating element and the heat dissipation element is adhered. For example, after the thermally conductive sheet is adhered to one of the heating element and the heat dissipation element in the above-mentioned pressure-bonding step, the pressure is released and the carrier film is peeled off from the thermally conductive sheet. This step can obtain one of the heating element and the heat dissipation element to which the thermally conductive sheet is adhered. In addition, a release layer may be provided between the carrier film and the thermally conductive sheet, and in this case, the carrier film may be peeled off from the thermally conductive sheet via the release layer.

[0105] In a continuous roll-to-roll process, the carrier film from which the thermally conductive sheet has been peeled off is attached to a rotatable take-up roll upstream in the transport direction, and the take-up roll and the aforementioned unwinding roll are rotated to recover the carrier film from which the thermally conductive sheet has been peeled off, while a new thermally conductive sheet is transported and continuously pressed against either a new heating element or a new heat sink.

[0106] The manufacturing method of the present disclosure includes a step of bonding one of the heat generating element and the heat dissipating element to the side opposite to the side to which the other of the heat generating element and the heat dissipating element is bonded (hereinafter, also referred to as a "second bonding step"). In this step, the other of the heat generating element and the heat dissipating element is bonded to one of the heat generating element and the heat dissipating element to which the heat conducting sheet is bonded, thereby obtaining a heat dissipating device in which the heat conducting sheet is interposed between the heat generating element and the heat dissipating element. The preferred conditions of the pressure and the heating temperature in the second bonding step are not particularly limited as long as the heat conducting sheet can be bonded to the other of the heat generating element and the heat dissipating element. For example, the pressure may be 0.1 MPa to 2.0 MPa, or 0.15 MPa to 1.0 MPa. The heating temperature may be 80°C to 180°C, or 100°C to 170°C. When the heat conducting sheet with one surface exposed is bonded to the heat generating element, the heat generating element may be heated to perform the bonding.

[0107] In the manufacturing method of the present disclosure, the bonding conditions in the first and second compression bonding steps may be adjusted so that the ratio (compression rate) of the reduced thickness of the thermally conductive sheet after the second compression bonding step to the initial thickness of the thermally conductive sheet before the first compression bonding step is 5% to 35%.

[0108] (An example of a thermally conductive sheet holder) An example of a thermally conductive sheet holder will be described below with reference to FIG. 1 and FIG. 2. FIG. 1 is a side view showing an example of a thermally conductive sheet holder of the present disclosure. FIG. 2 is a view showing an area α corresponding to the dotted line portion in FIG. 1 as viewed from the cover film 1 side. Note that the cover film 1 is omitted in FIG. 2. As shown in FIG. 1, the thermally conductive sheet holder 10 includes a long carrier film 3, a plurality of thermally conductive sheets 2, and a long cover film 1 in this order. Furthermore, in the thermally conductive 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 thermally conductive sheets 2 as viewed from the cover film 1 side. A plurality of release films 4 are arranged along the longitudinal direction of the carrier film 3, and nine thermally conductive sheets are arranged on each of the plurality of release films. Moreover, the area α surrounded by a dotted circle in FIG. 1 corresponds to a gap formed by adjacent release films 4 and adjacent thermally conductive sheets 2 arranged on the adjacent release films, and has a convex shape as viewed from the front.

[0109] The thermally conductive sheet holder 10 has a configuration in which it is wound in a roll shape around a winding core 6 along the longitudinal direction, and in Fig. 1, a part of the thermally conductive sheet holder 10 wound in a roll shape is pulled out. In Fig. 1, the pulled out part of the thermally conductive sheet holder 10 is illustrated with emphasis on the winding core 6, and the relative relationship between the size of the pulled out part and the winding core 6 is not limited to this. In Fig. 1, the thermally conductive sheet holder 10 is wound in a roll shape so 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 this is not limited thereto, and the thermally conductive sheet holder 10 may also be wound in a roll shape so 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 width direction length of the carrier film 3 and the width direction length of the cover film 1 are greater than the width direction length of the thermally conductive sheet 2. The thermally conductive sheet 2 is not disposed at both ends of the carrier film 3 in the width direction, and a plurality of sprocket holes 7 for transporting the carrier film are provided at regular intervals along the longitudinal direction at both ends of the carrier film 3. The sprocket holes 7 provided at regular intervals are also used to position the thermally conductive sheet 2 when the carrier film is transported.

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

[0112] 3, the thermally conductive sheet holder 10 wound into a roll is attached to a pay-out roll 11 rotatable in the direction of the arrow X, and the cover film 1 is peeled off from the thermally conductive sheet holder 10 pulled out from the pay-out roll 11. The carrier film 3 of the thermally conductive sheet holder 10 from which the cover film 1 has been peeled off is attached to a take-up roll 16 which is rotatable in the direction of the arrow Z and is a fixed distance away from the pay-out roll 11. A press 14 is provided between the pay-out roll 11 and the take-up roll 16 in the transport direction to press the thermally conductive sheet 2 against the semiconductor chip 13, which is a heating element.

[0113] A sprocket roller (not shown) is disposed between the pay-out roll 11 and the take-up roll 16, and sprocket holes 7 are inserted into 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 thermally conductive sheet 2 arranged on the carrier film 3 is transported to the area facing the press machine 14.

[0114] After the thermally conductive sheet 2 arranged on the carrier film 3 is transported to an area facing the press machine 14, the thermally conductive sheet 2 is arranged between the press machine 14 and the semiconductor chip 13 arranged on the substrate 12, and the press machine 14 is used to apply pressure in the direction of the arrow Y to press the thermally conductive sheet 2 onto the semiconductor chip 13. Note that the configuration is not limited to one thermally conductive sheet 2 pressed onto one semiconductor chip 13 as shown in Fig. 3, and multiple thermally conductive sheets 2 may be pressed onto one semiconductor chip 13, or one or multiple thermally conductive sheets 2 may be pressed onto each of multiple semiconductor chips 13.

[0115] After the thermally conductive sheet 2 is pressed, the payout roll 11 and the take-up roll 16 are rotated to peel the carrier film 3 from the thermally conductive sheet 2 pressed onto the surface of the semiconductor chip 13 in region 15. At this time, the carrier film 3 is peeled off from the thermally conductive sheet 2 via a release layer (not shown), and the carrier film 3 with the release layer is collected by the take-up roll 16, and a substrate with a semiconductor chip to which the thermally conductive sheet 2 is pressed is obtained.

[0116] Then, the next thermally conductive sheet 2 carried by the carrier film 3 is pressure-bonded to the surface of the semiconductor chip 13 arranged on the next substrate with semiconductor chips, and the above-mentioned process is repeated to continuously mount the thermally conductive sheet 2 on the substrate with semiconductor chips. In this way, the thermally conductive sheet can be efficiently pressure-bonded to the heating element. EXAMPLES

[0117] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" is based on mass.

[0118] [Example 1] Several thermally conductive sheets were prepared, manufactured by Showa Denko Materials Co., Ltd., with a thickness of 150 μm, a longitudinal length of 30 mm, and a width of 50 mm. The sheets had a compressive modulus of 1.16 MPa when the compressive stress at 150°C was 0.10 MPa, a tack strength of 7.6 N·mm at 25°C, and a thermal conductivity of 16 W / (m·K). The thermally conductive sheets used flake-shaped expanded graphite particles ("HGF-L" by Showa Denko Materials Co., Ltd., mass average particle size: 270 μm, it was confirmed by the above-mentioned X-ray diffraction measurement method that the hexagonal ring planes in the crystals were oriented in the plane direction of the flake-shaped particles) as the thermally conductive filler. Further, the following long carrier film and long cover film were prepared. Also, the following adhesive layer and release film were prepared to be provided between the carrier film and the thermally conductive sheet. (Carrier film) Long PET film: Toray Industries, Inc. product name Lumirror S30, thickness 75 μm, width direction length 66 mm (Cover film) Long paper film: a laminate of silicone release agent / polyethylene / craft paper, product name SL-70S(U2) by Sumika Kakoshi Co., Ltd., total thickness 105μm, width length 66mm, peel strength to thermal conductive sheet 0mN / 25mm. Here, peel strength 0mN / 25mm means that the cover film had already peeled off when it was attached to a tensile tester so as to be pulled at a 90° angle to the interface with the thermal conductive sheet. (Adhesive layer) Acrylic resin double-sided tape: Neo Fix30, product name by Nikkei Shinka Co., Ltd., thickness 30 μm, width length 50 mm (Release film) PET film treated with release agent: Nippa Corporation's product name FU, thickness 75μm, width length 50mm, peeling force against thermal conductive sheet 18mN / 25mm

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

[0120] Six thermally conductive sheets were placed on each release film so that both ends of the release film in the width direction were aligned with both ends of the thermally conductive sheet in the width direction, and multiple release films with six thermally conductive sheets were arranged in the longitudinal direction. At this time, the shortest distance between adjacent thermally conductive sheets was adjusted to 20 mm.

[0121] Next, the two ends of the carrier film in the width direction and the two ends of the cover film in the width direction were arranged so as to coincide in a plan view, and the two or more heat conductive sheets were attached to the cover film and the carrier film in a state in which the two or more heat conductive sheets were sandwiched between the cover film and the carrier film. In this way, a long heat conductive sheet holder was manufactured that includes a long carrier film, an adhesive layer, a release film, a plurality of heat conductive sheets, and a long cover film in this order. A roll-shaped heat conductive sheet holder was obtained by winding this long heat conductive sheet holder around a winding core along the longitudinal direction so that the carrier film side was located on the winding core side. Note that when using a roll-shaped heat conductive sheet holder in the continuous roll-to-roll process shown in FIG. 3, it is necessary to pull out the heat conductive sheet holder and attach it to a winding roll before starting the pressure bonding process. In order to prevent the generation of a heat conductive sheet that cannot be used in the pressure bonding process, a heat conductive sheet was not provided between the cover film and the carrier film in a region of about 1 m in length that is first pulled out from the roll-shaped heat conductive sheet holder.

[0122] As shown in FIG. 3, a roll-shaped thermally conductive sheet holder was attached to a pay-out roll, and while peeling off the cover film from the thermally conductive sheet holder pulled out from the pay-out roll, the carrier film from the part where the cover film was peeled off and where the thermally conductive sheet was not provided was attached to a take-up roll, and the pay-out roll and the take-up roll were rotated to continuously transport a plurality of thermally conductive sheets on the carrier film. Using a press machine arranged between the pay-out roll and the take-up roll in the transport direction of the thermally conductive sheet, the thermally conductive sheet was pressed onto the surface of the semiconductor chip arranged on the substrate with the semiconductor chip under conditions of 25° C. and 0.8 MPa. After pressing, the take-up roll was rotated to peel off the carrier film from the thermally conductive sheet pressed onto the surface of the semiconductor chip, and the substrate with the semiconductor chip to which the thermally conductive sheet was pressed was collected. Then, the next thermally conductive sheet transported by the carrier film was pressed onto the surface of the semiconductor chip arranged on the substrate with the next semiconductor chip, and the above-mentioned process was repeated, whereby the thermally conductive sheet could be continuously mounted on the substrate with the semiconductor chip. Furthermore, in this embodiment, when the cover film is peeled off from the thermally conductive sheet via the release layer, the thermally conductive sheet does not peel off from the carrier film side and is not transferred to the cover film side, and misalignment of the thermally conductive sheet when attached to the semiconductor chip, which can occur when the thermally conductive sheet is peeled off from the carrier film side, is also suppressed.

[0123] [Example 2] A long thermally conductive sheet holder was manufactured in the same manner as in Example 1, except that the release film in Example 1 was changed from Nippa Corporation's product name FU to Nippa Corporation's product name X1-A3 (thickness 75 μm, width length 50 mm, peel strength to thermally conductive sheet 38 mN / 25 mm).

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

[0125] [Example 3] A long thermally conductive sheet holder was manufactured in the same manner as in Example 1, except that the release film in Example 1 was changed from Nippa Corporation's product name FU to Fujimori Kogyo Co., Ltd.'s product name 75E-0010 (thickness 75 μm, width length 50 mm, peel strength to thermally conductive sheet 50 mN / 25 mm).

[0126] For the thermally conductive sheet holder produced in Example 3, the thermally conductive sheet was pressure-bonded to the substrate with the semiconductor chip in the same manner as in Example 1. When peeling the carrier film from the thermally conductive sheet pressure-bonded to the surface of the semiconductor chip after pressure bonding, it was more difficult to peel the carrier film from the thermally conductive sheet than in Example 2, and the thermally conductive sheet was more likely to be damaged.

[0127] [Example 4] A long thermally conductive sheet holder was manufactured in the same manner as in Example 1, except that the cover film in Example 1 was changed from Sumika Kakoshi Co., Ltd.'s product name SL-70S (U2) to Nippa Corporation's product name FU (thickness 75 μm, width length 66 mm, peel strength to thermally conductive sheet 18 mN / 25 mm).

[0128] For the thermally conductive sheet holder produced in Example 4, the thermally conductive sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling off the cover film, a part of the thermally conductive sheet was more likely to stick to the cover film side than in Example 1, and the thermally conductive sheet was more likely to be damaged.

[0129] [Example 5] A long thermally conductive sheet holder was manufactured in the same manner as in Example 1, except that the cover film in Example 1 was changed from Sumika Kakoshi Co., Ltd.'s product name SL-70S (U2) to Lintec Corporation's product name SP-8LK (thickness 88 μm, width length 66 mm, peel strength to thermally conductive sheet 8 mN / 25 mm).

[0130] For the thermally conductive sheet holder produced in Example 5, a thermally conductive sheet was pressure-bonded to a substrate with a semiconductor chip in the same manner as in Example 1. When peeling off the cover film, a part of the thermally conductive sheet was more likely to stick to the cover film side than in Example 1, and the thermally conductive sheet was more likely to be damaged.

[0131] [Example 6] A long thermally conductive sheet holder was manufactured in the same manner as in Example 4, except that the release film in Example 4 was changed from Nippa Corporation's product name FU to Fujimori Kogyo Co., Ltd.'s product name 75E-0010 (thickness 75 μm, width length 50 mm, peel strength to thermally conductive sheet 50 mN / 25 mm).

[0132] For the thermally conductive sheet holder produced in Example 6, the thermally conductive sheet was pressure-bonded to the substrate with a semiconductor chip in the same manner as in Example 1. When peeling off the cover film, a part of the thermally conductive sheet was more likely to stick to the cover film side than in Example 1, and the thermally conductive sheet was more likely to be damaged.

[0133] The disclosure of PCT / JP2020 / 039140, filed October 16, 2020, is incorporated herein by reference in its entirety. All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0134] 1 Cover film 2. Thermal Conductive Sheet 3. Carrier Film 4 Release film 5 Adhesive layer 6 Winding core 7 Sprocket Holes 10. Heat-conducting sheet holder 11 Payout roll 12 Substrate 13 Heating element 14 Press machine 15 areas 16 Winding roll

Claims

1. A long carrier film, a plurality of thermally conductive sheets, and a long cover film covering the plurality of thermally conductive sheets, in this order; The shortest distance between adjacent thermally conductive sheets is 2 mm or more; The plurality of thermally conductive sheets are arranged at intervals in a longitudinal direction of the carrier film and the cover film, and the plurality of thermally conductive sheets are peelable from the cover film; A release layer is further provided between the carrier film and the plurality of thermally conductive sheets, and the plurality of thermally conductive sheets can be peeled from the carrier film via the release layer; A plurality of the release layers are disposed along the longitudinal direction of the carrier film, One or more of the thermally conductive sheets are disposed on each of the plurality of release layers; When the cover film is positioned vertically downward and the carrier film is positioned vertically upward, the shape of the gap formed by adjacent release layers and adjacent thermal conduction sheets positioned on adjacent release layers, respectively, is a convex shape when viewed in the width direction of the thermal conduction sheet holder.

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

3. 3. The thermally conductive sheet holder according to claim 1, wherein the average thickness of the thermally conductive sheet is 50 μm to 500 μm.

4. 4. The thermally conductive sheet holder according to claim 1, wherein the thermally conductive sheet contains a thermally conductive filler and a resin.

5. 5. The thermally conductive sheet holder according to claim 1, which is wound into a roll shape along the longitudinal direction.

6. A thermal conductive sheet holder according to any one of claims 1 to 5, wherein in a width direction perpendicular 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 thermal conductive sheet.

7. A method for manufacturing a heat dissipation device, comprising: manufacturing a heat dissipation device by using the heat conductive sheet holder according to any one of claims 1 to 6, the heat dissipation device being formed by interposing the heat conductive sheet between a heating body and a heat dissipation body, peeling the cover film from the thermally conductive sheet holder; a step of pressing the thermally conductive sheet onto one of a heat generating body and a heat dissipating body in the thermally conductive sheet holder from which the cover film has been peeled off; peeling off the carrier film from the thermally conductive sheet to which one of the heat generating element and the heat dissipating element is adhered; a step of pressing the other of the heat generating element and the heat dissipating element onto a side of the thermally conductive sheet opposite to a side onto which the other of the heat generating element and the heat dissipating element is adhered; A method for manufacturing a heat dissipation device comprising:

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