Manufacturing method for heat conductive sheet holder and 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 heat conduction sheet holder and a heat dissipation device.

Background Art

[0002] In recent years, the heat generation amount has increased due to the high density of wiring and mounting density of electronic components in semiconductor packages using multilayer wiring boards, and the heat generation amount per unit area has increased 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 adhering 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 more excellent in workability when assembling the heat dissipation device than the heat conduction grease.

[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 a heat conduction filler (boron nitride) is 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

[0006] While it is possible to manufacture a heat dissipation device by sandwiching a heat conductive sheet, as described in Patent Documents 1 and 2, between a heat-generating element such as a semiconductor package and a heat sink such as aluminum or copper, and ensuring close contact, the increasing demand for heat dissipation devices has led to a need for efficient methods for manufacturing such devices, as well as for heat conductive sheets used in such methods.

[0007] This disclosure has been made in view of the above, and aims to provide a heat conductive sheet holder that can efficiently manufacture a heat dissipation device, and a method for manufacturing a heat dissipation device using this heat conductive sheet holder. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following embodiments. <1> A heat conductive sheet holder comprising, in this order, a long carrier film, a plurality of heat conductive sheets, and a long cover film covering the plurality of heat conductive sheets, wherein 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 are peelable from the cover film and the carrier film. <2> A release layer is further provided between the carrier film and the plurality of heat conductive sheets, and the plurality of heat conductive sheets can be peeled off from the carrier film via the release layer. <1> The heat conductive sheet holder described above. <3> The carrier film comprises a plurality of release layers arranged along its longitudinal direction, with one or more heat conductive sheets placed on each of the plurality of release layers. <2> The heat conductive sheet holder described above. <4> When the cover film is positioned vertically downwards and the carrier film is positioned vertically upwards, the shape of the gap formed by adjacent release layers and adjacent heat conductive sheets positioned between adjacent release layers is convex when viewed from the width direction of the heat conductive sheet holder. <3> The heat conductive sheet holder described above. <5> The peeling force between the carrier film and the thermal conductive sheet is greater than the peeling force between the cover film and the thermal conductive sheet. <1> ~ <4> A heat conductive sheet holder as described in any one of the following. <6> The average thickness of the thermal conductive sheet is 50 μm to 500 μm. <1> ~ <5> A heat conductive sheet holder as described in any one of the following. <7> The aforementioned heat-conducting sheet contains a heat-conducting filler and a resin. <1> ~ <6> A heat conductive sheet holder as described in any one of the following. <8> It is wound into a roll along the longitudinal direction. <1> ~ <7> A heat conductive sheet holder as described in any one of the following. <9> In the 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 greater than the width of the thermal conductive sheet. <1> ~ <8> A heat conductive sheet holder as described in any one of the following. <10> The shortest distance between adjacent thermal conductive sheets is 2 mm or more. <1> ~ <9> A heat conductive sheet holder as described in any one of the following. <11> No cuts have occurred on the surface of the carrier film. <1> ~ <10> A heat conductive sheet holder as described in any one of the following.

[0009] <12> <1> ~ <11> A method for manufacturing a heat dissipation device, comprising: a step of peeling the cover film from the heat conductive sheet holder; a step of pressing the heat conductive sheet onto one of the heat heating element and the heat dissipation element in the heat conductive sheet holder from which the cover film has been peeled off; a step of peeling the carrier film from the heat conductive sheet to which one of the heat heating element and the heat dissipation element is adhered; and a step of pressing the other of the heat heating element and the heat dissipation element onto the side of the heat conductive sheet opposite to the side to which one of the heat heating element and the heat dissipation element is adhered. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide a heat conductive sheet holder that can efficiently manufacture a heat dissipation device, and a method for manufacturing a heat dissipation device using this heat conductive sheet holder. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a side view showing an example of a thermal conductive sheet holder according to this disclosure. [Figure 2] Figure 2 shows the region α corresponding to the dotted line in Figure 1, viewed from the cover film 1 side. [Figure 3] Figure 3 is a schematic diagram showing part of the manufacturing process in an example of a heat dissipation device manufacturing method. [Modes for carrying out the invention]

[0012] The embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the present invention. In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes, provided that the purpose of such process is achieved. In this disclosure, the numerical range indicated using "~" includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this disclosure, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, the content of each component in the composition refers to the total content of those multiple substances present in the composition. In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where, when observing the region in which the layer exists, it is formed not only over the entire region but also over only a portion of the region. In this disclosure, the term "lamination" refers to stacking layers, and two or more layers may be bonded together or detachable. In this disclosure, the thickness of the layer is defined as the arithmetic mean of the thicknesses of five points on the layer in question. The thickness of a layer can be measured using a micrometer or the like. In this disclosure, if the thickness of a layer can be measured directly, it is measured using a micrometer. On the other hand, when measuring the thickness of a single layer or the total thickness of multiple layers, it may be measured by observing the cross-section of the object to be measured using an electron microscope. When embodiments are described with reference to the drawings in the present disclosure, 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] <Thermal conduction sheet holder> The thermal conduction sheet holder of the present disclosure includes, in this order, a long carrier film, a plurality of thermal conduction sheets, and a long cover film covering the plurality of thermal conduction sheets. The plurality of thermal conduction sheets are arranged at intervals in the longitudinal direction of the carrier film and the cover film, and the plurality of thermal conduction sheets are detachable from the cover film and the carrier film.

[0014] In the thermal conduction sheet holder of the present disclosure, a plurality of thermal conduction sheets are arranged on a long carrier film, and together with the carrier film, the plurality of thermal conduction sheets can be transported. Thereby, while transporting the plurality of thermal conduction sheets from which the cover film has been peeled off from the thermal conduction sheet holder together with the carrier film, the thermal 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 thermal 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 thermal conduction sheet holder may be wound around a winding core. By pulling out the thermal conduction sheet holder wound in a roll shape and peeling off the cover film from the thermal conduction sheet, it becomes possible to continuously mount the thermal 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 conductive sheet holder of this disclosure comprises a long carrier film. The carrier film is a long film member for transporting heat conductive sheets, and a plurality of heat conductive sheets are arranged on the carrier film at intervals along its longitudinal direction, either directly or via a release layer described later. The carrier film is peelable from the heat conductive sheets.

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

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

[0019] From the viewpoint of easily peeling the carrier film from the thermal conductive sheets, a release layer may be provided between the carrier film and the multiple thermal conductive sheets, and the carrier film may be peelable from the multiple thermal 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 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. Furthermore, the release layer, such as a release film, may be provided on the carrier film via an adhesive layer, and in the thermal conductive sheet holder of this disclosure, the carrier film, adhesive layer, release layer, and thermal conductive sheets may be laminated in that 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 considering the strength of the carrier film, the 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 even more preferably 50 μm to 100 μm.

[0021] When a release layer is provided between the carrier film and multiple thermal conductive sheets, the average thickness of the release layer is not particularly limited, but from the viewpoint of release properties of the thermal conductive sheets and miniaturization of the thermal 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 with a release agent surface treatment, the average thickness of the release film is not particularly limited, but from the viewpoint of ensuring adhesive properties and miniaturizing the heat 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 adhesives used in the adhesive layer include commonly used acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, silicone adhesives, and mixtures thereof. The adhesive layer may also contain components other than the adhesive, such as crosslinking agents and tackifiers. The average thickness of the adhesive layer is not particularly limited, but from the viewpoint of ensuring adhesive properties and miniaturizing the heat 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 thermal conductive sheet holder of this disclosure comprises a long cover film. The cover film is a long member for covering and protecting a plurality of thermal conductive sheets. The cover film is peelable from the thermal conductive sheets.

[0024] The cover film is not particularly limited and can include the aforementioned resin films that may be included in the carrier film, paper films such as fine paper, coated paper, kraft 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 consisting of one of the aforementioned films, metal foils, etc., or it may be a multilayer film in which two or more layers of the aforementioned films, metal foils, etc. are laminated together.

[0025] Furthermore, release layers may be provided on the multiple heat-conducting sheet-side surfaces of the cover film, and the cover film may be peelable from the multiple heat-conducting sheets via the release layers. The release layer may be, for example, a layer containing a release agent such as a silicone-based or silica-based agent. If the cover film is a paper film, a layer containing polyethylene or the like, which functions as a sealant, may be placed between the layer containing the release agent and the paper film, from the viewpoint of suppressing the penetration of the release agent into the paper film.

[0026] The average thickness of the cover film is not particularly limited, but from the viewpoint of the strength of the cover film and miniaturization of the heat conductive 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, if a release layer, and optionally a layer containing polyethylene, etc., are provided on 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 heat conductive sheet holder of this disclosure, it is preferable that no cuts occur on the surface of the cover film, carrier film, or release film, preferably on the surface on the heat conductive sheet side, and more preferably that no cuts occur due to cutting by dicing, laser processing, etc. In particular, it is preferable that no cuts occur on the surface of the cover film or carrier film, and more preferably that no cuts occur on the surface of the carrier film. When no cuts occur on these films, it is suppressed that these films will break or deform when tensile stress is applied to the heat conductive sheet holder. As a result, problems such as the inability to continuously press the heat conductive sheet to the adherend using the heat conductive sheet holder, and the inability to accurately press the heat conductive sheet to the adherend due to misalignment of the relative positions between multiple heat conductive sheets in the heat conductive sheet holder are suppressed. In particular, by not having cuts in the carrier film, even when pressing the heat conductive sheet to the adherend in a continuous process as shown in Figure 3, as described later, breakage of the carrier film due to tensile stress, misalignment of the heat conductive sheet on the carrier film, etc. are suitably suppressed.

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

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

[0030] When a release layer is provided between the carrier film and multiple heat conductive sheets, the release force between the release layer and the heat conductive sheets is greater than the release force between the cover film and the heat conductive sheets. It is preferable that the latter is larger.

[0031] The peel force between the cover film and the thermal conductive sheet is preferably 0mN / 25mm to 30mN / 25mm, more preferably 0mN / 25mm to 10mN / 25mm, and even more preferably 0mN / 25mm to 5mN / 25mm. Here, a peel force of 0mN / 25mm indicates that the cover film has already peeled off when it is attached to the tensile testing machine so that it is pulled at a 90° angle to the interface with the thermal conductive sheet. The peel force between the cover film and the thermal conductive sheet in this disclosure is the maximum peel strength obtained when a laminated film with a width of 25 mm is prepared and the cover film is pulled in a direction 90° relative to the interface with the thermal conductive sheet using a tensile testing machine under conditions of a tensile speed of 100 mm / min and a temperature of 23°C, thereby peeling the cover film from the thermal conductive sheet.

[0032] The peeling force between the carrier film and the thermal conductive sheet, preferably between the release layer placed between the carrier film and the thermal conductive sheet and the thermal conductive sheet, is preferably 5mN / 25mm to 50mN / 25mm, more preferably 10mN / 25mm to 30mN / 25mm, and even more preferably 12mN / 25mm to 30mN / 25mm. The peel force between the carrier film or release layer and the thermal conductive sheet in this disclosure is the maximum peel strength obtained when a laminated film with a width of 25 mm is prepared and the carrier film or release layer is pulled in a direction of 90° relative to the interface with the thermal conductive sheet using a tensile testing machine under conditions of a tensile speed of 100 mm / min and a temperature of 23°C, thereby separating the carrier film or release layer from the thermal conductive sheet.

[0033] The peeling force between the carrier film and the thermal conductive sheet (preferably the peeling force between the release layer placed between the carrier film and the thermal conductive sheet and the thermal conductive sheet) is preferably greater than the peeling force between the cover film and the thermal conductive sheet. The difference between these forces is preferably 5mN / 25mm to 30mN / 25mm, more preferably 10mN / 25mm to 25mN / 25mm, and even more preferably 15mN / 25mm to 20mN / 25mm.

[0034] Sheet-like materials such as thermal conductive sheets may have an adhesive component on the side facing the cover film, from the viewpoint of adhesion to the adherend. In the sheet-like material holder, the sheet-like material is held in a state where the cover film does not come into contact with the sheet-like material, thus preventing the sheet-like material from adhering to the cover film due to the adhesive component.

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

[0036] The average thickness of the thermal conductive sheet is not particularly limited and can be appropriately selected depending on the purpose. Specifically, the average thickness of the thermal conductive sheet can be 50 μm to 500 μm, and from the viewpoint 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 thermal conductive sheet is not particularly limited and may be appropriately changed according to the shape of the heat-generating element and heat-dissipating element to which the thermal conductive sheet is attached. The shape of the main surface of the thermal conductive sheet may be circular, elliptical, polygonal, etc.

[0038] If the main surface of the heat conductive sheet has a polygonal shape, preferably a rectangular or other quadrilateral shape, one side The length may be between 3mm and 100mm, or between 5mm and 80mm.

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

[0040] Regarding multiple thermal conductive sheets arranged at intervals along the longitudinal direction of the carrier film and cover film, the shortest distance between adjacent thermal conductive sheets may be 2 mm or more, 2 mm to 100 mm, 5 mm to 60 mm, or 5 mm to 30 mm. When the shortest distance between adjacent thermal conductive sheets is 2 mm or more, interference between adjacent thermal conductive sheets and the thermal conductive sheet being pressed against a substrate such as a heat-generating element or heat-sinking element can be suppressed. This tends to suppress damage to other thermal conductive sheets and unintended adhesion of other thermal conductive sheets to the substrate. Furthermore, when the shortest distance between adjacent thermal conductive sheets is 100 mm or less, productivity tends to be superior when pressing thermal conductive sheets against substrates such as heat-generating elements and heat-sinking elements.

[0041] The heat conductive sheet holder of this disclosure may have a plurality of release layers arranged along the longitudinal direction of the carrier film between the carrier film and the plurality of heat conductive sheets, and one or more heat conductive sheets may be placed on each of the plurality of release layers. Alternatively, two or more heat conductive sheets may be placed on each of the plurality of release layers, and 2 to 50 heat conductive sheets may be placed. By arranging multiple release layers, deflection of the release layers and displacement of the heat conductive sheets due to deflection tend to be suppressed.

[0042] Furthermore, when the heat conductive sheet holder of this disclosure is arranged such that the cover film is on the lower vertical side and the carrier film is on the upper vertical side, it is preferable that the shape of the gap formed by adjacent release layers and adjacent heat conductive sheets arranged on adjacent release layers is convex when viewed from the width direction of the heat conductive sheet holder. As a result, on the surface where multiple heat conductive sheets are arranged on the release layers, there are no heat conductive sheets at both ends in the longitudinal direction, making it easier to peel the carrier film from the heat conductive sheets.

[0043] If the shape of the gap described above is convex when viewed from the width direction of the heat 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 heat conductive sheets (vertical lower side of the convex shape / vertical upper side of the convex shape) may be greater than 1 and 300 or less, may be between 1.2 and 50, or may be between 1.5 and 10.

[0044] If the shape of the gap described above is convex when viewed from the width direction of the heat 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 widthwise length of the carrier film and the widthwise length of the cover film are preferably greater than the widthwise length of the thermal conductive sheet. A larger widthwise length of the carrier film allows for easier transport of the carrier film and easier peeling of the carrier film from the thermal conductive sheet. Furthermore, the width of the cover film... By having a directional length greater than the widthwise length of the thermal conductive sheet, the thermal conductive sheet can be adequately protected, and the cover film can be easily peeled off the thermal conductive sheet.

[0046] The ratio of the widthwise length of the carrier film to the widthwise length of the thermal conductive sheet (widthwise length of the carrier film / widthwise length of the thermal conductive sheet) is preferably greater than 1 and 15 or less, 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 thermal conductive sheet (widthwise length of the cover film / widthwise length of the thermal conductive sheet) is preferably greater than 1 and 15 or less, more preferably 1.05 to 10, and even more preferably 1.1 to 5.

[0048] From the viewpoint of transportability, it is preferable that the heat conductive sheet holder of this disclosure does not have heat conductive sheets arranged at both ends in the width direction of the carrier film, and it is more preferable that multiple 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 multiple sprocket holes at regular intervals, it becomes easy to arrange multiple heat conductive sheets at regular intervals along the longitudinal direction of the carrier film based on the spacing of the sprocket holes, and it also becomes easier to position the heat conductive sheets when pressing them against either the heating element or the heat sink.

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

[0050] In the thermal conductive sheet used in this disclosure, from the viewpoint of making the thermal conductive sheet more easily crushed and more easily adhering to the other of the heat generating element and heat dissipating element under the high-temperature pressing conditions of the second compression process described later, it is preferable that the compressive modulus of elasticity when the compressive stress at 150°C is 1.4 MPa or less, more preferably 1.3 MPa or less, and even more preferably 1.2 MPa or less. There is no particular lower limit to the compressive modulus of elasticity when the compressive stress at 150°C is 0.1 MPa. The above compressive modulus of elasticity may be 0.5 MPa or more, or 0.7 MPa or more.

[0051] The compressive modulus of a thermal conductive sheet can be measured using a compression testing 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 strain (dimensionless) obtained from displacement (mm) / thickness (mm) is plotted on the horizontal axis, and the load (N) / area (mm) is plotted on the horizontal axis. 2 The stress (MPa) obtained by ) is shown on the vertical axis, and the slope at a predetermined stress is defined as the compressive modulus (MPa). Specifically, it can be measured, for example, by the method described in the examples.

[0052] In the thermal conductive sheet used in this 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, it is possible to suppress the thermal conductive sheet from peeling off the heat-generating element and the heat-sinking element when warping occurs in the heat dissipation device equipped with the thermal conductive sheet and the distance between the heat-generating element and the heat-sinking element increases. There is no particular upper limit to the tack force. The above tack force may be 20.0 N·mm or less, or 15.0 N·mm or less.

[0053] The tack force of a thermal conductive sheet at 25°C is measured using a universal physical properties tester (e.g., a textured sheet). Measurement can be performed using a Nalyzer (Eiko Seiki Co., Ltd.). At 25°C (room temperature), a 7mm diameter probe is pressed against a thermal conductive sheet with a load of 40N and held for 10 seconds. The area obtained by integrating the load and displacement curve when the probe is lifted is defined as the tack force (N·mm) at 25°C.

[0054] The thermal conductive sheet used in this disclosure preferably satisfies the aforementioned conditions for both the compressive modulus of elasticity when the compressive stress at 150°C is 0.1 MPa and the tack force at 25°C.

[0055] As mentioned above, a thermal 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, while a thermal 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 soft or highly adhesive thermal conductive sheets and mount them onto heating elements, heat sinks, etc., there is a problem in that the soft or highly adhesive thermal conductive sheets themselves are prone to deformation and breakage, making it difficult to easily peel them off from the base material such as a protective sheet, or the thermal conductive sheet itself is deformed or broken after peeling, making it unusable for mounting heating elements, heat sinks, etc.

[0056] On the other hand, with the heat conductive sheet holder of this disclosure, the aforementioned pick-up is not necessary when mounting the heat conductive sheet onto a heat generating element, heat sink, etc., and the heat conductive sheet can be continuously mounted onto the heat generating element, heat sink, etc. while suppressing deformation, breakage, etc. of the heat conductive sheet itself, thus providing excellent handling of the heat conductive sheet and manufacturing efficiency of the heat dissipation device.

[0057] The above-mentioned compressive modulus and tack force can be obtained, for example, by adjusting the blending ratio of each component used in the thermal conductive sheet. The following describes the preferred composition of the thermal conductive sheet.

[0058] ≪Thermal Conductive Filler≫ The thermal conductive sheet preferably contains thermal conductive fillers. The thermal conductive fillers are not particularly limited as long as they are thermally conductive fillers. Examples of thermal conductive fillers 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 one type of thermal conductive filler may be used alone, or two or more types may be used in combination.

[0059] As the thermal conductive filler, graphite particles are particularly preferred due to their low thermal resistance and excellent thermal conductivity, and at least one type of graphite particle selected from the group consisting of flake-shaped particles, ellipsoidal particles, and rod-shaped particles, as 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 that employs the laser diffraction and scattering method (for example, the "Microtrac series MT3300" manufactured by Nikkiso Co., Ltd.). When the weight-cumulative particle size distribution curve is plotted from the small particle size side, it corresponds to the particle size at which the weight cumulative reaches 50%.

[0061] The particle size distribution of the thermal conductive filler is not particularly limited. The particle size distribution, when plotted with particle size on the x-axis and frequency on the y-axis, may be a monodisperse system with a single peak or a polydisperse system with multiple peaks. Furthermore, the particle size distribution may be narrow or broad.

[0062] The content of thermal conductive filler in the thermal conductive sheet is preferably 15% to 50% by volume, more preferably 20% to 45% by volume, and even more preferably 25% to 40% by volume, from the viewpoint of balancing thermal conductivity and adhesion to heat-generating elements, heat-sinking elements, etc. preferable. When the thermal conductive filler content is 15% by volume or more, thermal conductivity tends to improve further. When the thermal conductive filler content is 50% by volume or less, the decrease in tackiness and adhesion to heat-generating elements, heat sinks, etc. tends to be more effectively suppressed.

[0063] The thermal conductive filler content (volume %) is calculated using the following formula. Thermal conductive filler content (volume %) = (Aw / Ad) / ((Aw / Ad)+(Bw / Bd)+(Cw / Cd))×100 Aw: Mass composition (mass%) of thermal conductive filler Bw: Mass composition of the resin (mass %) Cw: Mass composition (mass%) of other optional components Ad: Density of thermal conductive fillers Bd: Density of resin Cd: Density of other optional components

[0064] The thermal conductive filler may contain at least one type of graphite particle selected from the group consisting of flake-shaped particles, ellipsoidal particles, and rod-shaped particles. Furthermore, if the graphite particles are flake-shaped particles, they may be oriented in the plane direction; if the graphite particles are ellipsoidal particles, they may be oriented along the long axis; or if the graphite particles are rod-shaped particles, they may be oriented along the long axis. With this configuration, the thermal conductive sheet has low thermal resistance and excellent thermal conductivity.

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

[0066] The orientation of the six-membered ring planes within the graphite particle crystal can be confirmed by X-ray diffraction measurements. Specifically, the orientation of the six-membered ring planes within the graphite particle crystal is confirmed by the following method.

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

[0068] A sheet is formed from a mixture of resin and graphite particles in an amount of 10% or more by volume relative to the resin. The "resin" used here is not particularly limited as long as it is a material that does not produce peaks that interfere with X-ray diffraction and is capable of forming a sheet. Specifically, amorphous resins with cohesive force 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 less than 1 / 10 of its original thickness, and multiple pressed sheets are stacked to form a laminate. This laminate is further compressed to less than 1 / 10 of its original thickness, and this process is repeated three or more times to obtain a sample sheet for measurement. Through this process, the graphite particles in the sample sheet are oriented in the plane direction if they are flake-shaped particles, in the longitudinal direction if they are ellipsoidal particles, and in the longitudinal direction if they are rod-shaped particles, along the plane direction of the sample sheet.

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

[0071] Therefore, the statement that "the six-membered ring planes in the crystal of graphite particles are oriented in the plane direction in the case of flake-shaped particles, in the longitudinal axis direction in the case of ellipsoidal particles, and in the longitudinal axis direction in the case of rod-shaped particles" refers to a state in which, when X-ray diffraction measurements are performed on the surface of a sheet containing graphite particles, the value obtained by dividing the height of the peak corresponding to the (110) plane of the graphite particles appearing around 2θ=77° by the height of the peak corresponding to the (002) plane of the graphite particles appearing around 2θ=27° is between 0 and 0.02.

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

[0073] Here, "the graphite particles are oriented in the plane direction in the case of flake-shaped particles, in the longitudinal axis direction in the case of ellipsoidal particles, and in the longitudinal axis direction in the case of rod-shaped particles" means that the angle between the plane direction in the case of flake-shaped particles, the longitudinal axis direction in the case of ellipsoidal particles, and the longitudinal axis direction in the case of rod-shaped particles and the surface of the heat-conducting 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 obtained by observing the cross-section of the thermal conductive sheet with a scanning electron microscope (SEM) and measuring the angle (orientation angle) between the thermal conductive sheet surface (main surface) and any 50 graphite particles: in the case of flake-shaped particles, in the direction of the long axis in the case of ellipsoidal particles, and in the direction of the long axis in the case of rod-shaped particles.

[0075] The particle size of the graphite particles is not particularly limited. Preferably, the average particle size of the graphite particles is between half the average thickness of the thermal conductive sheet and the average thickness. When the average particle size of the graphite particles is half or more the average thickness of the thermal conductive sheet, efficient heat conduction paths are formed in the thermal conductive sheet, and the thermal conductivity tends to improve. When the average particle size of the graphite particles is less than or equal to the average thickness of the thermal conductive sheet, the protrusion of graphite particles from the surface of the thermal conductive sheet is suppressed, and the adhesion to the surface of the thermal conductive sheet tends to be excellent.

[0076] Furthermore, when using a laminated slicing method as described in Japanese Patent Publication No. 2008-280496, the particle size of the graphite particles used as raw material is preferably at least half the average thickness of the thermal conductive sheet as a mass-average particle size, and may exceed the average thickness. The reason why the particle size of the graphite particles used as raw material may exceed the average thickness of the thermal conductive sheet is that, for example, even if the thermal conductive sheet contains graphite particles with a particle size exceeding the average thickness of the thermal conductive sheet, the thermal conductive sheet is formed by slicing together with the graphite particles, so as a result the graphite particles do not protrude from the surface of the thermal conductive sheet. In addition, when the thermal conductive sheet is sliced ​​together in this way, a large number of graphite particles that penetrate in the thickness direction of the thermal conductive sheet are generated, forming extremely efficient heat conduction paths, and the thermal conductivity tends to be further improved.

[0077] When using the laminated slicing method, the particle size of the graphite particles used as raw material is more preferably 1 to 5 times the average thickness of the thermal conductive sheet, as a mass-average particle size. If the mass-average particle size of the graphite particles is 1 or more times the average thickness of the thermal conductive sheet, more efficient heat conduction paths are formed, and thermal conductivity is further improved. If it is 5 times or less the average thickness of the thermal conductive sheet, the surface area occupied by 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 thermal conductive filler is preferably, for example, 50% to 100% by volume, more preferably 80% to 100% by volume, even more preferably 95% to 100% by volume, and particularly preferably 100% by volume, relative to the total volume of the thermal conductive filler.

[0079] The thermal conductive sheet may contain graphite particles other than flake-shaped particles, ellipsoidal particles, and rod-shaped particles, and may also contain spheroidal graphite particles, artificial graphite particles, flake-shaped graphite particles, acid-treated graphite particles, expanded graphite particles, carbon fiber flakes, etc. As for the graphite particles, flake-shaped particles are preferred, and from the viewpoint of obtaining flakes with a high degree of crystallinity and large particle size, flake-shaped expanded graphite particles obtained by crushing sheet-formed expanded graphite are preferred.

[0080] ≪Resin≫ It is preferable that the thermal conductive sheet contains a resin. The inclusion of a resin in the thermal conductive sheet tends to result in a thermal conductive sheet with excellent flexibility and good adhesion to heat-generating elements, heat-sinking elements, etc.

[0081] The resin is not particularly limited and may be curable or non-curable, for example. Examples of resins include epoxy resins, silicones, acrylic resins, polyimide resins, bismaleimide resins, benzocyclobutene resins, phenolic resins, unsaturated polyesters, diallyl phthalate resins, polyurethanes, polyimide silicones, thermosetting polyphenylene ethers, thermosetting modified polyphenylene ethers, polybutenes, polyisoprene, polysulfide, acrylonitrile rubber, silicone rubber, hydrocarbon resins, terpene resins, terpene phenolic resins, and hydrogenated terpene phenols. One type of resin may be used alone or two or more types may be used in combination.

[0082] The resin content in the thermal conductive sheet is preferably selected according to the type of resin and the desired flexibility, tackiness, 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 thermal conductive sheet may contain other components besides the thermal conductive filler and resin, depending on the purpose. For example, the thermal conductive sheet may contain a flame retardant for the purpose of providing flame retardancy.

[0084] The flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. Examples include red phosphorus-based flame retardants and phosphate ester-based flame retardants. Among these, phosphate ester-based flame retardants are preferred because they offer superior safety and improved adhesion due to their plasticity effect.

[0085] As red phosphorus-based flame retardants, in addition to pure red phosphorus powder, various coatings applied to enhance safety or stability, or masterbatch-formed products may also be used. Specifically, examples include NovaRed, NovaExcel, NovaQuel, and NovaPellet (all trade names) manufactured by Phosphorus Chemical Industry Co., Ltd.

[0086] Examples of phosphate ester-based flame retardants include aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, and tributyl phosphate; triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, trixylenyl phosphate, cresyl-2,6-xylenyl phosphate, and tris(t-butylated phenyl) phosphate. Examples include aromatic phosphate esters such as phosphate, tris(isopropylated phenyl) phosphate, and triarylisopropylated 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 exhibits excellent hydrolysis resistance and superior adhesion improvement due to its plasticizing effect.

[0087] The amount of flame retardant in the heat conductive sheet is not limited and can be used in an amount that exhibits flame retardancy. It is preferably 40% by volume or less, and preferably 30% by volume or less, in order to suppress deterioration of thermal resistance due to the flame retardant component seeping out onto the surface of the heat conductive sheet.

[0088] The thermal conductive sheet may contain additives such as antioxidants, radical trapping agents, and pH adjusters as needed, and preferably contains 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 thermal conductive sheet.

[0089] [Method for manufacturing a heat conductive sheet holder] A method for manufacturing a thermal conductive sheet holder is, for example, the following: The manufacturing method includes the steps of: preparing a composition containing thermal conductive filler, resin, and other components as needed (also called the "preparation step"); forming the composition into a sheet to obtain a sheet (also called the "sheet manufacturing step"); stacking multiple sheets and folding one of the sheets, or rolling up one of the sheets to produce a laminate (also called the "laminated body manufacturing step"); slicing the side end face of the laminate (slicing step); and sandwiching the sliced ​​thermal conductive sheets between a cover film and a carrier film to laminate the multiple thermal conductive sheets (laminating step).

[0090] The thermal conductive sheets contained in thermal conductive sheet holders manufactured by this method tend to form efficient thermal conduction paths, and therefore exhibit high thermal conductivity and excellent adhesion.

[0091] <Preparation process> The preparation of the composition constituting the thermal conductive sheet may be carried out by any method that allows for the uniform mixing of the thermal conductive filler, resin, and other components as needed, and is not particularly limited. Alternatively, the composition may be prepared using commercially available materials. Details of the preparation of the composition can be found in paragraph

[0033] of Japanese Patent Application Publication No. 2008-280496.

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

[0034] of Japanese Patent Application Publication No. 2008-280496.

[0093] <Laminate fabrication process> The laminate manufacturing process forms a laminate of the sheets obtained in the previous process. The laminate is not limited to a form in which multiple independent sheets are stacked in sequence, but may also be a form in which a single sheet is folded without being cut, or a form in which a single sheet is rolled up. Details of the laminate manufacturing process can be found in paragraphs

[0035] to

[0037] of Japanese Patent Application Publication No. 2008-280496.

[0094] <Slicing process> The slicing process can be carried out by any method that allows for slicing of the side end faces of the laminate obtained in the previous step, and is not particularly limited. From the viewpoint of forming extremely efficient heat conduction paths by graphite particles penetrating in the thickness direction of the heat conduction sheet and further improving heat conductivity, it is preferable to slice to a thickness of twice the mass-average particle diameter of the graphite particles or less. Details of the slicing process can be found in paragraph

[0038] of Japanese Patent Application Publication No. 2008-280496.

[0095] <Lamination process> The lamination process can be carried out by any method, as long as it involves sandwiching multiple sliced ​​thermal conductive sheets between a cover film and a carrier film or a cover film and a release film, and then attaching the multiple thermal conductive sheets to the cover film and the carrier film or release film. For example, the sliced ​​thermal conductive sheets may be cut to a predetermined size, then the multiple thermal conductive sheets may be placed on the cover film, carrier film or release film, and then the placed multiple thermal conductive sheets may be sandwiched between the cover film and the carrier film or the cover film and a release film, and the thermal conductive sheets may be attached to these to obtain a thermal conductive sheet holder. In addition to the above method, for example, the sliced ​​thermal conductive sheets may be placed on the cover film, carrier film or release film, the thermal conductive sheets may be cut to a predetermined size by punching or the like, and then the multiple cut thermal conductive sheets may be sandwiched between the cover film and the carrier film or the cover film and a release film, and the thermal conductive sheets may be attached to these to obtain a thermal conductive sheet holder.

[0096] For example, in the lamination process, it is possible to place multiple heat conductive sheets on a cover film, carrier film, or release film by placing a long heat conductive sheet on the cover film, carrier film, or release film and cutting the long heat conductive sheet by dicing, laser processing, etc. However, when a long heat conductive sheet is cut by dicing, laser processing, etc., the cover film, carrier film, or release film on which the long heat conductive sheet is placed may also be partially cut in the thickness direction, resulting in notches. If notches occur on these films, there is a risk that these films may break or deform when tensile stress is applied to the resulting heat conductive sheet holder. As a result, problems such as the inability to continuously press the heat conductive sheets to the adherend using the heat conductive sheet holder, and the inability to accurately press the heat conductive sheets to the adherend due to misalignment of the relative positions between multiple heat conductive sheets in the heat conductive sheet holder, are likely to occur. These problems are particularly likely to occur when notches occur in the cover film or carrier film, and if notches occur in the carrier film, the continuous process shown in Figure 3, which will be described later, becomes difficult.

[0097] From the above points, it is preferable that the lamination process includes arranging multiple heat conductive sheets on a cover film, carrier film, or release film, or cutting the heat conductive sheets arranged on the cover film, carrier film, or release film by punching or the like. This prevents or suppresses cuts in the cover film, carrier film, or release film, and effectively suppresses tearing, deformation, etc. of the film when tensile stress is applied to the heat conductive sheet holder. Furthermore, unlike when a long heat conductive sheet is cut by dicing, laser processing, etc., it becomes easy to arrange multiple heat conductive sheets such that the shortest distance between adjacent heat conductive sheets is 2 mm or more.

[0098] <Manufacturing method for heat dissipation devices> A method for manufacturing a heat dissipation device according to the present disclosure is a method for manufacturing a heat dissipation device in which a heat conductive sheet is interposed between a heat generating element and a heat dissipation element using a heat conductive sheet holder according to the present disclosure, comprising the steps of peeling the cover film from the heat conductive sheet holder and peeling the cover film A method for manufacturing a heat dissipation device, comprising the steps of: pressing the heat conductive sheet onto one of the heating element and the heat sink in the heat conductive sheet holder from which the film has been peeled off; peeling the carrier film off the heat conductive 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 onto the heat conductive sheet on the side opposite to the side to which one of the heating element and the heat sink is adhered.

[0099] The heat dissipation device obtained by the manufacturing method of this disclosure has a heat-generating element and a heat sink laminated together via a thermal conductive sheet, which allows for efficient transfer of heat from the heat-generating element to the heat sink. Furthermore, the thermal conductive sheet can be easily removed when detaching the heat sink from the heat-generating element.

[0100] The manufacturing method of the present disclosure includes a step of peeling the cover film from the heat conductive sheet holder. For example, if the heat conductive sheet holder of the present disclosure is wound in a roll shape, the cover film may be peeled off while the heat conductive sheet holder is fed out with the roll-shaped heat conductive sheet holder attached to a rotatable feed roll.

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

[0102] Examples of heat-generating elements 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 sinks include heat sinks using aluminum or copper fins or plates, aluminum or copper blocks connected to heat pipes, aluminum or copper blocks in which a cooling liquid is circulated by a pump, and Peltier elements and aluminum or copper blocks equipped with them.

[0103] The pressure and heating temperature in the first crimping process are not particularly limited, as long as it is possible to adhere the heat conductive sheet to either the heating element or the heat sink. For example, the aforementioned pressure may be 0.1 MPa to 4.0 MPa or 0.15 MPa to 2.0 MPa. The aforementioned heating temperature may be 15°C to 100°C or 20°C to 35°C. When crimping the heat conductive sheet to the heating element, the heating element may be heated before crimping.

[0104] The manufacturing method of the present disclosure includes a step of peeling a carrier film from a thermal conductive sheet to which one of the heating element and the heat sink is adhered. For example, after pressing the thermal conductive sheet to one of the heating element and the heat sink in the pressing step described above, the pressure can be released and the carrier film can be peeled off from the thermal conductive sheet. This step makes it possible to obtain one of the heating element and the heat sink to which the thermal conductive sheet is adhered. Alternatively, a release layer may be provided between the carrier film and the thermal conductive sheet, in which case the carrier film may be peeled off from the thermal conductive sheet via the release layer.

[0105] In a continuous roll-to-roll process, the carrier film from which the heat conductive sheet has been peeled off may be attached to a rotatable winding roll on the upstream side in the conveying direction. By rotating the winding roll and the aforementioned dispensing roll, the carrier film from which the heat conductive sheet has been peeled off may be recovered while a new heat conductive sheet is conveyed, and the process of pressing it with one of the new heating elements and heat sinks may be carried out continuously.

[0106] The manufacturing method of the present disclosure includes a step of pressing the other heat-generating element and heat-sinking element onto the side of the heat-conducting sheet opposite to the side to which one of the heat-generating elements and heat-sinking elements is bonded (hereinafter also referred to as the "second pressing step"). This process includes the following steps: In this step, the other of the heating element and heat sink is pressed against one of the heating element and heat sink to which the heat conductive sheet is bonded, thereby obtaining a heat dissipation device in which the heat conductive sheet is interposed between the heating element and the heat sink. The preferred conditions for pressure and heating temperature in the second pressing step are not particularly limited as long as it is possible to bond the heat conductive sheet to the other of the heating element and heat sink. For example, the aforementioned pressure may be 0.1 MPa to 2.0 MPa or 0.15 MPa to 1.0 MPa. Also, the aforementioned heating temperature may be 80°C to 180°C or 100°C to 170°C. When pressing a heat conductive sheet with one side exposed against a heating element, the heating element may be heated before pressing.

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

[0108] (An example of a thermal conductive sheet holder) An example of a heat conductive sheet holder will be described below using Figures 1 and 2. Figure 1 is a side view showing an example of the heat conductive sheet holder of this disclosure. Figure 2 is a view of the region α corresponding to the dotted line in Figure 1, as seen from the cover film 1 side. Note that the cover film 1 is omitted in Figure 2. As shown in Figure 1, the heat conductive sheet holder 10 comprises a long carrier film 3, a plurality of heat conductive sheets 2, and a long cover film 1 in this order. Furthermore, in the heat conductive sheet holder 10, a release film 4 and an adhesive layer 5 are arranged between the carrier film 3 and the plurality of heat conductive sheets 2, as seen 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 heat conductive sheets are arranged on each of the plurality of release films. The region α enclosed by the dotted line of the circle in Figure 1 corresponds to the gap formed by adjacent release films 4 and adjacent heat conductive sheets 2 arranged on adjacent release films, and its shape is convex when viewed from the front.

[0109] The thermal conductive sheet holder 10 has a structure in which it is wound in a roll shape along the longitudinal direction on a winding core 6, and in Figure 1, a part of the roll-shaped thermal conductive sheet holder 10 is pulled out. Note that in Figure 1, the pulled-out portion of the thermal conductive sheet holder 10 is exaggerated compared to the winding core 6, and the relative relationship between the size of the pulled-out portion and the winding core 6 is not limited to this. Also, in Figure 1, the thermal conductive sheet holder 10 is wound in a roll shape with the cover film 1 on the outside and the carrier film 3 on the inside relative to the central axis, but it is not limited to this, and the thermal conductive sheet holder 10 may be wound in a roll shape with the cover film 1 on the inside and the carrier film 3 on the outside relative 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 thermal conductive sheet 2. The thermal conductive sheet 2 is not positioned at both ends of the carrier film 3 in the widthwise direction, and multiple sprocket holes 7 for transporting the carrier film are provided at regular intervals along the longitudinal direction of both ends of the carrier film 3. The sprocket holes 7, which are provided at regular intervals, are also used to position the thermal conductive sheet 2 when transporting the carrier film.

[0111] (An example of a heat dissipation device manufacturing method) The following describes an example of a heat dissipation device manufacturing method using Figure 3. Figure 3 is a schematic diagram showing part of the manufacturing process in an example of a heat dissipation device manufacturing method. In Figure 3, the release film 4 and adhesive layer 5 are omitted.

[0112] As shown in Figure 3, the heat conductive sheet holder 10, which is wound into a roll, is attached to a feed roll 11 that is rotatable in the direction of arrow X, and the heat conductive sheet is drawn out from the feed roll 11. The cover film 1 is peeled off from the heat conductive sheet holder 10. The carrier film 3 of the heat conductive sheet holder 10 from which the cover film 1 has been peeled off is attached to a winding roll 16 that is rotatable in the direction of arrow Z, at a certain distance from the feed roll 11. A press machine 14 is provided between the feed roll 11 and the winding roll 16 in the transport direction to press the heat conductive sheet 2 onto the semiconductor chip 13, which is a heat-generating element.

[0113] A sprocket roller (not shown) is positioned between the feed roll 11 and the take-up roll 16. Sprocket holes 7 are inserted through sprocket pins provided at equal intervals on the surface of the sprocket roller. By rotating the feed roll 11 in the direction of arrow X and the take-up roll 16 in the direction of arrow Z, the heat conductive sheet 2 placed on the carrier film 3 is conveyed to the area facing the press machine 14.

[0114] After the thermal conductive sheet 2, which is placed on the carrier film 3, is transported to the area facing the press machine 14, the thermal conductive sheet 2 is pressed against the semiconductor chip 13 by applying pressure in the direction of arrow Y using the press machine 14 while the thermal conductive sheet 2 is positioned between the press machine 14 and the semiconductor chip 13 placed on the substrate 12. Note that the configuration is not limited to pressing one thermal conductive sheet 2 onto one semiconductor chip 13 as shown in Figure 3, but multiple thermal conductive sheets 2 may be pressed onto one semiconductor chip 13, or one or more thermal conductive sheets 2 may be pressed onto each of multiple semiconductor chips 13.

[0115] After the thermal conductive sheet 2 is pressed, the feed roll 11 and the winding roll 16 are rotated to peel the carrier film 3 from the thermal conductive sheet 2 pressed onto the surface of the semiconductor chip 13 in region 15. At this time, the carrier film 3 is peeled from the thermal conductive sheet 2 via a release layer (not shown), and the carrier film 3 with the release layer attached is recovered by the winding roll 16, and a substrate with a semiconductor chip to which the thermal conductive sheet 2 has been pressed is obtained.

[0116] Then, the next thermal conductive sheet 2, transported by the carrier film 3, is pressed against the surface of the semiconductor chip 13 placed on the next semiconductor chip-equipped substrate, and by repeating the above process, the thermal conductive sheets 2 can be continuously mounted onto the semiconductor chip-equipped substrate. In this way, the thermal conductive sheets can be efficiently pressed against the heating element. [Examples]

[0117] The present invention will be described in 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] Multiple thermal conductive sheets were prepared, each 150 μm thick, with a carrier film length of 30 mm in the longitudinal direction and a width of 50 mm, manufactured by Showa Denko Materials Co., Ltd. These sheets had a compressive modulus of 1.16 MPa at a compressive stress of 0.10 MPa at 150°C, a tack force of 7.6 N·mm at 25°C, and a thermal conductivity of 16 W / (m·K). These thermal conductive sheets used flaky expanded graphite particles (Showa Denko Materials Co., Ltd. "HGF-L", mass-average particle diameter: 270 μm; the six-membered ring plane in the crystal was confirmed to be oriented in the plane direction of the flaky particles by the aforementioned X-ray diffraction measurement method). Furthermore, the following long carrier film and long cover film were prepared. In addition, the following adhesive layer and release film were prepared to be placed between the carrier film and the heat conductive sheet. (Career film) Long roll of PET film: Toray Industries, Inc. product name Lumirror S30, thickness 75 μm, width length 66 mm (Cover film) Long paper film: Laminate of silicone release agent / polyethylene / kraft paper, product name SL-70S(U2) of Sumika Kako Paper Co., Ltd., total thickness 105 μm, width length 66 mm, peel force against thermal conductive sheet 0 mN / 25 mm. Here, a peel force of 0 mN / 25 mm indicates that the cover film had already peeled off when it was attached to the tensile testing machine so as to be pulled at a 90° angle to the interface with the thermal conductive sheet. (Adhesive layer) Acrylic resin double-sided tape: Product name Neo Fix30, manufactured by Nichiei Shinka Co., Ltd., thickness 30μm, width 50mm (Release film) PET film treated with release agent: Product name FU from Nippa Co., Ltd., thickness 75 μm, width 50 mm, peel force against thermal conductive sheet 18 mN / 25 mm

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

[0120] Six thermal conductive sheets were placed on each release film so that the ends of the release film in the width direction coincided with the ends of the thermal conductive sheets in the width direction. Multiple release films with six thermal conductive sheets each were then arranged along the longitudinal direction. At this time, the shortest distance between adjacent thermal conductive sheets was adjusted to 20 mm.

[0121] Next, the carrier film was positioned so that both ends in the width direction coincided with the cover film in the width direction in a plan view, and multiple heat conductive sheets were attached to the cover film and carrier film with the multiple heat conductive sheets sandwiched between the cover film and carrier film. This produced a long heat conductive sheet holder comprising a long carrier film, an adhesive layer, a release film, multiple 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 onto a winding core along its longitudinal direction so that the carrier film side was located on the winding core side. When using the roll-shaped heat conductive sheet holder in the continuous roll-to-roll process shown in Figure 3, it is necessary to pull out the heat conductive sheet holder and attach it to the winding roll before starting the crimping process. To avoid generating heat conductive sheets that cannot be used in the crimping process, no heat conductive sheet was provided between the cover film and carrier film in the area of ​​approximately 1 m in length that is first pulled out from the roll-shaped heat conductive sheet holder.

[0122] As shown in Figure 3, a roll-shaped thermal conductive sheet holder was attached to a feed roll. The cover film was peeled off the thermal conductive sheet holder pulled out from the feed roll, and the carrier film in the portion where the cover film had been peeled off and no thermal conductive sheet was attached was attached to a winding roll. The feed roll and winding roll were rotated to continuously transport multiple thermal conductive sheets on the carrier film. Using a press machine positioned between the feed roll and winding roll in the direction of thermal conductive sheet transport, the thermal conductive sheets were pressed onto the surface of semiconductor chips placed on a substrate with semiconductor chips at a temperature of 25°C and a pressure of 0.8 MPa. After pressing, the winding roll was rotated to peel off the carrier film from the thermal conductive sheets pressed onto the surface of the semiconductor chips, and the substrate with semiconductor chips to which the thermal conductive sheets were pressed was recovered. Then, the next thermal conductive sheet transported by the carrier film was pressed onto the surface of a semiconductor chip placed on the next substrate with semiconductor chips, and the above process was repeated to continuously mount thermal conductive sheets onto the substrate with semiconductor chips. Furthermore, in this embodiment, when the cover film is peeled off from the thermal conductive sheet via the release layer, the thermal conductive sheet peels off from the carrier film side and the thermal conductive sheet There was no transfer to the cover film side, and misalignment of the thermal conductive sheet when it was attached to the semiconductor chip, which could occur due to the thermal conductive sheet peeling off from the carrier film side, was also suppressed.

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

[0124] In Example 2, the thermal conductive sheet holder manufactured in Example 2 was used to press a thermal conductive sheet onto a substrate with a semiconductor chip in the same manner as in Example 1. When peeling the carrier film from the thermal conductive sheet pressed onto the surface of the semiconductor chip after pressing, it was more difficult to peel the carrier film from the thermal conductive sheet than in Example 1, and the thermal conductive sheet was more prone to damage.

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

[0126] In Example 3, the thermal conductive sheet holder manufactured was used to press-bond the thermal conductive sheet to a substrate with a semiconductor chip in the same manner as in Example 1. When peeling the carrier film from the thermal conductive sheet pressed onto the surface of the semiconductor chip after bonding, it was more difficult to peel the carrier film from the thermal conductive sheet than in Example 2, and the thermal conductive sheet was more prone to damage.

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

[0128] In Example 4, a thermal conductive sheet was pressed onto a semiconductor chip substrate using the thermal conductive sheet holder manufactured in the same manner as in Example 1. When peeling off the cover film, a portion of the thermal conductive sheet was more likely to stick to the cover film than in Example 1, and the thermal conductive sheet was more prone to damage.

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

[0130] In Example 5, a thermal conductive sheet was pressed onto a semiconductor chip-equipped substrate using the thermal conductive sheet holder manufactured in the same manner as in Example 1. When peeling off the cover film, a portion of the thermal conductive sheet was more likely to stick to the cover film than in Example 1, and the thermal conductive sheet was more prone to damage.

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

[0132] In Example 6, a thermal conductive sheet was pressed onto a semiconductor chip-equipped substrate using the thermal conductive sheet holder manufactured in the same manner as in Example 1. When peeling off the cover film, a portion of the thermal conductive sheet was more likely to stick to the cover film than in Example 1, and the thermal conductive sheet was more prone to damage.

[0133] The disclosure of PCT / JP2020 / 039140, filed on 16 October 2020, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted 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 cores 7 sprocket holes 10 Thermal conductive sheet holder 11 Feed Roll 12 circuit boards 13 Heating element 14 Press machine 15 areas 16 reel rolls

Claims

1. The device comprises, in this order, a long carrier film, a plurality of heat conductive sheets, and a long cover film that covers the plurality of heat conductive sheets. The shortest distance between adjacent thermal 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 are peelable from the cover film. A release layer is further provided between the carrier film and the plurality of heat conductive sheets, and the plurality of heat conductive sheets can be peeled off from the carrier film via the release layer. The carrier film comprises a plurality of release layers arranged along the longitudinal direction, One or more of the heat conductive sheets are placed in each of the plurality of release layers. A heat conductive sheet holder in which, 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 heat conductive sheets positioned on adjacent release layers is convex when viewed from the width direction of the heat conductive sheet holder.

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

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

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

5. A heat conductive 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 conductive sheet holder according to any one of claims 1 to 5, wherein in the 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 greater than the width of the heat conductive sheet.

7. A method for manufacturing a heat dissipation device, comprising interposing a heat conductive sheet between a heat generating element and a heat dissipating element using a heat conductive sheet holder according to any one of claims 1 to 6, A step of peeling the cover film from the heat conductive sheet holder, The heat conductive sheet holder from which the cover film has been peeled off includes the step of pressing the heat conductive sheet onto one of the heating element and the heat dissipation element, A step of peeling the carrier film from the heat conductive sheet to which one of the heating element and the heat sink is adhered, A step of pressing the other heating element and the heat sink onto the side of the heat conductive sheet opposite to the side to which one of the heating element and the heat sink is adhered, A method for manufacturing a heat dissipation device equipped with the following:

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