Semiconductor device production method, thermally conductive sheet, and thermally conductive sheet production method

Abstract

A method for manufacturing a semiconductor device includes a process of applying pressure in the thickness direction of a heat-conducting sheet to a heating element and a heat dissipating element disposed between a heat-conducting sheet, wherein the compressive elastic modulus at 150°C is 1.40 MPa or less when the compressive stress at 150°C is 0.10 MPa and the tack force at 25°C is 5.0 N·mm or more, and thereby bonding the heating element and the heat dissipating element with the heat-conducting sheet interposed therebetween.

Description

Technology Field

[0001] The present disclosure relates to a method for manufacturing a semiconductor device, a thermal conductive sheet, and a method for manufacturing a thermal conductive sheet. Background Technology

[0002] Recently, there is a demand to improve the heat dissipation of semiconductor packages, accompanied by the increase in wiring density of multilayer circuit boards, the increase in wiring density of semiconductor packages, the increase in mounting density of electronic components, and the increase in heat generation per unit area due to the high integration of the semiconductor devices themselves.

[0003] Among them, excellent heat dissipation is required for semiconductor devices with high heat generation, such as CPUs (Central Processing Units) and power devices. These semiconductor devices have a structure that dissipates heat by inserting a thermally conductive material, such as grease or a thermally conductive sheet, between a heat source and a heat dissipation element, such as aluminum or copper, and ensuring close contact (see, for example, Patent Documents 1 to 4). Prior art literature

[0004] Patent Document 1: Japanese Patent Publication No. Hei 05-247268 Patent Document 2: Japanese Patent Publication No. Hei 10-298433 Patent Document 3: Patent No. 4743344 Patent Document 4: Patent No. 5316254 The problem to be solved

[0005] Recently, along with the increase in performance of semiconductor packages, semiconductor chips and packages are becoming larger. Due to this increase in size, when grease is used as a thermal conductive material, pump-out is prone to occur during thermal cycling, making it difficult to ensure sufficient heat dissipation. On the other hand, when a thermal conductive sheet is used as a thermal conductive material, the amount of warping of the semiconductor chip or package increases due to the increase in the size of the heating element, so the thermal conductive sheet is prone to peeling off from the heating element and heat dissipation element, making it difficult to secure heat dissipation.

[0006] Taking these circumstances into account, the present disclosure aims to provide a method for manufacturing a semiconductor device with excellent heat dissipation properties, a thermal conductive sheet capable of manufacturing a semiconductor device with excellent heat dissipation properties, and a method for manufacturing said thermal conductive sheet. means of solving the problem

[0007] Means for solving the above problem include the following aspects.

[0008] <1> A method for manufacturing a semiconductor device, comprising a process of applying pressure in the thickness direction of a heat-conducting sheet to a heating element and a heat dissipating element disposed between a heat-conducting sheet having a compressive elastic modulus of 1.40 MPa or less when the compressive stress at 150℃ is 0.10 MPa and a tack force of 5.0 N·mm or more at 25℃, and bonding the heating element and the heat dissipating element with the heat-conducting sheet interposed therebetween.

[0009] <2> The thermal conductivity of the thermal conductive sheet, obtained from the thermal resistance measured by the normal method, is 7 W / (m·K) or higher, <1> A method for manufacturing a semiconductor device as described in [the document].

[0010] <3> The above pressure is 0.05 MPa to 10.00 MPa, <1> or <2> A method for manufacturing a semiconductor device as described in [the document].

[0011] <4> The above pressure is 0.10 MPa to 0.50 MPa, <3> A method for manufacturing a semiconductor device as described in [the document].

[0012] <5> The above heating element is a semiconductor chip, and the above heat dissipation element is a heat spreader. <1> ~ <4> A method for manufacturing a semiconductor device as described in any one of the claims.

[0013] <6> The surface area of ​​the side of the heating element facing the heat-conducting sheet is 25 mm² or more, <1> ~ <5> A method for manufacturing a semiconductor device as described in any one of the claims.

[0014] <7> The above heating element is a semiconductor package having a heat spreader, and the above heat dissipation element is a heat sink. <1> ~ <4> A method for manufacturing a semiconductor device as described in any one of the claims.

[0015] <8> The above heating element is a semiconductor module, <1> ~ <4> A method for manufacturing a semiconductor device as described in any one of the claims.

[0016] <9> The surface area of ​​the side of the heating element facing the heat-conducting sheet is 100 mm² or more, <1> ~ <8> A method for manufacturing a semiconductor device as described in any one of the claims.

[0017] <10> A heat-conducting sheet having a compressive modulus of 1.40 MPa or less when the compressive stress at 150℃ is 0.10 MPa, and a tack force at 25℃ of 5.0 N·mm or more, disposed between a heating element and a heat sink of a semiconductor device and used for bonding the heating element and the heat sink.

[0018] <11> A thermal conductivity of 7 W / (m·K) or higher, obtained from thermal resistance measured by the normal method <10> The thermal conductive sheet listed in

[0019] <12> The above heating element is a semiconductor chip, and the above heat dissipation element is a heat spreader. <10> or <11> The thermal conductive sheet listed in

[0020] <13> The above heating element is a semiconductor package having a heat spreader, and the above heat dissipation element is a heat sink. <10> or <11> The thermal conductive sheet listed in

[0021] <14> The above heating element is a semiconductor module, <10> or <11> The thermal conductive sheet listed in

[0022] <15> A method for manufacturing a heat conductive sheet, wherein, for a heating element and a heat dissipating element disposed between a heat conductive sheet, a heat conductive sheet is applied pressure while heating in the thickness direction of the heat conductive sheet to bond the heating element and the heat dissipating element with the heat conductive sheet interposed therebetween, the method comprises selecting the compression ratio and thickness of the heat conductive sheet such that the compression amount of the heat conductive sheet satisfies the following formula.

[0023] Formula: C>L2-L1

[0024] L1: Predicted amount of bending (μm) of the heating element when heated and pressurized

[0025] L2: Predicted amount of warping (μm) of the heating element when cooled to 25℃ after terminating heating and pressurization

[0026] C: Predicted compression amount (μm) of the heat conductive sheet under heating and pressurizing conditions

[0027] C = Thickness of the heat-conducting sheet before pressurization (μm) × Compression ratio under heating and pressurization conditions (%) Effects of the invention

[0028] According to the present disclosure, a method for manufacturing a semiconductor device with excellent heat dissipation properties, a thermal conductive sheet capable of manufacturing a semiconductor device with excellent heat dissipation properties, and a method for manufacturing said thermal conductive sheet are provided. Brief explanation of the drawing

[0029] [Fig. 1] A schematic cross-sectional view of a semiconductor device when a thermal conductive sheet is used as TIM1. [Fig. 2] A figure illustrating the amount of bending in a semiconductor device when a thermal conductive sheet is used as TIM1. Specific details for implementing the invention

[0030] The following describes in detail embodiments for carrying out the present invention. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not mandatory unless specifically stated otherwise. The same applies to numerical values ​​and their ranges, and this does not limit the present invention.

[0031] In the present disclosure, the term "process" includes, in addition to a process independent of another process, a process that cannot be clearly distinguished from another process, provided that the purpose of the process is achieved.

[0032] In the numerical range indicated by "~" in the present disclosure, the numerical values ​​listed before and after "~" are included as the minimum and maximum values, respectively.

[0033] In numerical ranges described stepwise in the present disclosure, an upper or lower limit described in one numerical range may be substituted with an upper or lower limit of a numerical range described in another stepwise manner. Additionally, in numerical ranges described in the present disclosure, an upper or lower limit of said numerical range may be substituted with a value shown in an example.

[0034] In the present disclosure, each component may include multiple types of the corresponding substance. Where multiple types of substances corresponding to each component exist in the composition, the content or content of each component refers to the content or content of the total sum of the multiple substances present in the composition, unless specifically determined otherwise.

[0035] In the present disclosure, particles corresponding to each component may be included in multiple types. Where multiple types of particles corresponding to each component exist in the composition, the particle size of each component refers to the value of the mixture of said multiple types of particles present in the composition, unless specifically determined otherwise.

[0036] In the present disclosure, the term "layer" includes cases where, when observing the region in which the layer exists, it is formed in the entire region, in addition to cases where it is formed only in a part of the region.

[0037] In the present disclosure, the term "laminated" refers to stacking layers upon layers, and two or more layers may be combined, or two or more layers may be detachable.

[0038] When embodiments of the present disclosure are described with reference to the drawings, the configuration of said embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the members in each drawing are conceptual, and the relative relationships of the sizes between members are not limited thereto.

[0039] Method for manufacturing a semiconductor device

[0040] The method for manufacturing a semiconductor device according to the present disclosure comprises a process of applying pressure in the thickness direction of a heat-conducting sheet to a heating element and a heat dissipating element disposed between a heat-conducting sheet, wherein the compressive elastic modulus at 150°C is 1.40 MPa or less when the compressive stress at 150°C is 0.10 MPa and the tack force at 25°C is 5.0 N·mm or more, and thereby bonding the heating element and the heat dissipating element with the heat-conducting sheet interposed therebetween. According to the method for manufacturing a semiconductor device according to the present disclosure, delamination of the heat-conducting sheet is suppressed, and a semiconductor device with excellent heat dissipation properties can be manufactured.

[0041] [Heating element]

[0042] The heating element in the present disclosure is an object that dissipates heat by adhering a heat dissipation element via a heat-conducting sheet. Examples of heating elements include semiconductor chips, semiconductor packages, automotive power modules, industrial power modules, etc. Furthermore, the heating element does not necessarily mean that the member itself in contact with the heat-conducting sheet is capable of generating heat. For example, when the heat-conducting sheet is used for the TIM2 described below, the heat-conducting sheet comes into contact with a heat spreader provided in a semiconductor package; in this case, the semiconductor package equipped with said heat spreader is referred to as a "heating element."

[0043] The size of the heating element is not particularly limited. For example, when a heat-conducting sheet is used for the TIM1 described below, the surface area of ​​the heating element facing the heat-conducting sheet may be 25 mm² or more, 100 mm² or more, 200 mm² or more, or 400 mm² or more. The surface area of ​​the heating element facing the heat-conducting sheet may be, for example, 15,000 mm² or less, 5,000 mm² or less, or 2,000 mm² or less.

[0044] When the heat-conducting sheet is used for the TIM2 described below, the surface area of ​​the heating element facing the heat-conducting sheet may be 100 mm² or more, 400 mm² or more, or 1000 mm² or more. The surface area of ​​the heating element facing the heat-conducting sheet may be, for example, 40,000 mm² or less, 20,000 mm² or less, or 5,000 mm² or less.

[0045] When the heat-conducting sheet is used for the power device described below, the surface area of ​​the heating element facing the heat-conducting sheet may be 100 mm² or more, 400 mm² or more, or 1000 mm² or more. The surface area of ​​the heating element facing the heat-conducting sheet may be, for example, 40,000 mm² or less, 20,000 mm² or less, or 5,000 mm² or less.

[0046] [Heat dissipation]

[0047] The heat dissipator in the present disclosure is a member that dissipates heat from a heat source by interposing a heat-conducting sheet. Examples of heat dissipators include heat spreaders, heat sinks, water-cooling pipes, etc.

[0048] [Heat Conductive Sheet]

[0049] The thermal conductive sheet of the present disclosure is a sheet used for bonding the heating element and the heat sink by being placed between a heating element and a heat sink of a semiconductor device. In the present disclosure, "sheet" refers to a sheet-like product that is not in a liquid state and is distinguished from liquid grease, etc. Here, "liquid state" refers to a substance having a viscosity of 1,000 Pa·s or less at 25°C. The viscosity is 5.0 s using a rheometer at 25°C. -1 It is defined as the value measured at a shear rate. Viscosity is measured as shear viscosity at a temperature of 25°C using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0°).

[0050] When grease is used as a thermal conductive material between a heating element and a heat dissipating element, there is a possibility that thermal resistance may increase due to pump-out during thermal cycling; however, since the manufacturing method of the present disclosure uses a thermal conductive sheet, pump-out does not occur.

[0051] In addition, when a sheet is used as a thermal conductive material, there were cases where delamination of the sheet occurred along with an increase in the amount of bending of the heating element, resulting in a failure to obtain the desired heat dissipation performance. However, the thermal conductive sheet used in the present disclosure can maintain a sufficient adhesion area between the heating element and the heat dissipator by following the bending, even in semiconductor packages with increased bending. This ensures excellent heat dissipation characteristics. Although the reason for this is not necessarily clear, it is believed that when a thermal conductive sheet having the specific compressive elastic modulus and tack force is placed between the heating element and the heat dissipator and a press is performed, the thermal conductive sheet is sufficiently compressed while simultaneously adhering sufficiently to the heating element and the heat dissipator. Therefore, it is believed that even if the amount of bending changes after the press, the adhesion area can be maintained by following the bending.

[0052] If the thermal conductive sheet is not peeled off from the heating element and the heat dissipation element and the adhesive area can be maintained, the increase in contact thermal resistance can be suppressed, and the deterioration of the heat dissipation characteristics of the semiconductor device can be suppressed. Therefore, it is desirable that the adhesive area between the thermal conductive sheet and the heating element and the heat dissipation element is maintained even if bending occurs in the heating element.

[0053] The thermal conductive sheet used in the present disclosure is used for bonding the heating element and the heat dissipation element by being placed between a semiconductor heating element and a heat dissipation element, and its use is not particularly limited. The thermal conductive sheet may, for example, be a thermal interface material (TIM1) placed between a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipation element. It may also be a thermal interface material (TIM2) placed between a semiconductor package, which is a heating element and has a heat spreader, and a heat sink, which is a heat dissipation element. Furthermore, it may be a thermal interface material (thermal interface material for power devices, etc.) placed between a semiconductor module, which is a heating element, and a heat dissipation element.

[0054] Among these, in the field of TIM1 where conventional grease is used, as the size of the heating element increases, it becomes difficult to ensure sufficient heat dissipation with grease, so the thermal conductive sheet used in the present disclosure is particularly useful.

[0055] Using FIG. 1, a specific example of the usage of a thermal conductive sheet when used as TIM1 is described. A thermal conductive sheet (1) is used by attaching one side to a semiconductor chip (2) (heating element) and attaching the other side to a heat spreader (3) (heat dissipation element). In FIG. 1, the semiconductor chip (2) (heating element) is fixed to a substrate (4) using an underfill material (5), and the heat spreader (3) (heat dissipation element) is fixed to the substrate (4) by a sealing material (6), thereby improving the adhesion between the thermal conductive sheet (1), the semiconductor chip (2), and the heat spreader (3) by pressing. By stacking the heating element and the heat dissipation element with the thermal conductive sheet interposed, heat from the heating element can be efficiently conducted to the heat dissipation element. If heat can be efficiently conducted, the lifespan of the semiconductor device is improved, and a semiconductor device that functions stably even during long-term use can be provided.

[0056] The thermal conductive sheet used in the present disclosure has a compressive modulus of 1.40 MPa or less when the compressive stress at 150°C is 0.10 MPa, and also has a tack force of 5.0 N·mm or more at 25°C. Since the compressive modulus and tack force satisfy the above ranges, it is believed that the thermal conductive sheet can maintain close contact with the heating element and the heat dissipator even in semiconductor devices where the amount of bending of the heating element is increased, thereby maintaining the adhesion area. It is believed that heat dissipation performance can be guaranteed.

[0057] It is believed that if the compressive modulus is 1.40 MPa or less when the compressive stress at 150℃ is 0.10 MPa, the flexibility is excellent, and when pressure (press) is applied, the heat-conducting sheet becomes easy to deform and adhere to the heating element and heat dissipator. In addition, it is believed that even if the bending of the heating element increases after pressing, the heat-conducting sheet adheres stably to the heating element and heat dissipator, thereby suppressing the reduction of the adhesion area.

[0058] The thermal conductive sheet preferably has a compressive elastic modulus of 1.40 MPa or less, 1.30 MPa or less, and more preferably 1.20 MPa or less when the compressive stress at 150°C is 0.10 MPa. If the compressive elastic modulus is 1.20 MPa or less, the adhesion is further improved, making it easier to follow bending. The lower limit of the compressive elastic modulus when the compressive stress at 150°C is 0.10 MPa is not particularly limited. The compressive elastic modulus may be 0.50 MPa or more, or 0.70 MPa or more.

[0059] The compressive modulus of a 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 at a displacement rate of 0.1 mm / min, and the displacement (mm) and load (N) are measured. The deformation (dimensionless) calculated as displacement (mm) / thickness (mm) is plotted on the horizontal axis, and the stress (MPa) calculated as load (N) / area (mm²) is plotted on the vertical axis, and the slope at a predetermined stress is defined as the compressive modulus (MPa). Specifically, it can be measured using the method described in the example.

[0060] The tack force of the heat conductive sheet at 25°C is 5.0 N·mm or more, preferably 6.0 N·mm or more, and more preferably 7.0 N·mm or more. If the tack force is 5.0 N·mm or more, it is possible to prevent the heat conductive sheet from peeling off from the heating element and the heat dissipator when bending occurs and the gap between the heating element and the heat dissipator increases. The upper limit of the tack force is not particularly limited. The above tack force may be 20.0 N·mm or less, and may be 15.0 N·mm or less.

[0061] The tack force of a thermal conductive sheet at 25°C can be measured using a universal physical property tester (e.g., a texture analyzer (Eco Seiki Co., Ltd.)). At 25°C (room temperature), a probe with a diameter of 7 mm is pressed firmly against the thermal conductive sheet with a load of 40 N and held for 10 seconds; the area obtained by integrating the load-displacement curve when the probe is pulled up is defined as the tack force (N·mm) at 25°C. Specifically, it can be measured by the method described in the example.

[0062] The method for obtaining a thermal conductive sheet having a compressive modulus of 1.40 MPa or less when the compressive stress at 150°C is 0.10 MPa and a tack force of 5.0 N·mm or more at 25°C is not particularly limited, and can be obtained, for example, by adjusting the type and mixing ratio of each component, such as thermal conductive filler and resin, used in the thermal conductive sheet.

[0063] The thermal conductivity of the thermal conductive sheet is not particularly limited, and a higher value is desirable. The thermal conductivity of the thermal conductive sheet, obtained from the thermal resistance measured by the normal method, is preferably 7 W / (m·K) or higher, more preferably 10 W / (m·K) or higher, and even more preferably 15 W / (m·K) or higher. If the thermal conductivity is 7 W / (m·K) or higher, it tends to be easy to suppress the increase in thermal resistance even if the thickness of the thermal conductive sheet is increased to improve the bending conformability to the heating element.

[0064] In the present disclosure, the thermal conductivity of the thermal conductive sheet is specifically calculated as follows.

[0065] A thermal conductive sheet is cut into 10 mm by 10 mm and placed between a heating element, a transistor (2SC2233), and a heat dissipation element, a copper block. When current is passed through the transistor while pressing it at 80°C and a pressure of 0.14 MPa, the temperature T1 (°C) of the transistor and the temperature T2 (°C) of the copper block are measured. Based on the measured values ​​and the applied power W1 (W), the thermal resistance value X (K·cm² / W) per unit area (1 cm²) is calculated as follows.

[0066] X=(T1-T2)×1 / W1

[0067] In addition, the thermal conductivity λ (W / (m·K)) is calculated as follows using the thickness t (μm).

[0068] λ=(t×10 -6 ) / (X×10 -4 )

[0069] The thickness of the thermal conductive sheet is not specifically limited and can be appropriately selected according to specifications such as the semiconductor package used. As the thickness decreases, thermal resistance tends to decrease, and as the thickness increases, bend-following ability tends to improve. The average thickness of the thermal conductive sheet may be 50 μm to 3000 μm, and from the perspective of thermal conductivity and adhesion, it is preferable to be 100 μm to 500 μm, and more preferable to be 150 μm to 300 μm. The average thickness of the thermal conductive sheet is determined by measuring the thickness at three locations using a micrometer and assigning the value as the arithmetic mean. The thickness of the thermal conductive sheet may be selected based on the amount of bending of the heating element, as described below.

[0070] The amount of compression of the thermal conductive sheet is not particularly limited. For example, when the compressive stress at 150°C is 0.10 MPa, the amount of compression may be 20 μm to 1000 μm, 30 μm to 200 μm, or 40 μm to 100 μm. When the compressive stress at 150°C is 0.15 MPa, the amount of compression may be the above values.

[0071] "Compression amount" of a heat conductive sheet is the amount of compression of the heat conductive sheet when pressure is applied in the thickness direction of the heat conductive sheet, and is the value obtained by subtracting the thickness of the heat conductive sheet when pressure is applied from the thickness of the heat conductive sheet before pressure is applied.

[0072] The compressibility of the thermal conductive sheet is not particularly limited. For example, the compressibility when the compressive stress at 150°C is 0.10 MPa may be 10% to 60%, 15% to 50%, or 15% to 40%. The compressibility when the compressive stress at 150°C is 0.15 MPa may also be the above values.

[0073] The "compression rate" of the thermal conductive sheet is the ratio (%) of the amount of compression (μm) to the thickness (μm) of the thermal conductive sheet before applying pressure.

[0074] A heat-conducting sheet may be prepared and used having a protective film on at least one side to protect the adhesive surface. In this case, the heat-conducting sheet from which the protective film has been peeled off is used for bonding the heating element and the heat dissipating element. As for the protective film, for example, resin films such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyethernaphthalate, methylpentene, polytetrafluoroethylene, ethylenetetrafluoroethylene copolymer, perfluoroalkoxyalkane, etc., coated paper, coated fabric, and metal foil such as aluminum may be used. These protective films may be used as a single type or combined into a multilayer film using two or more types. It is preferable that the protective film be surface-treated with a release agent such as a silicone-based or silica-based agent.

[0075] As long as the thermal conductive sheet satisfies the specific compressive modulus and tackiness mentioned above, the composition of the thermal conductive sheet is not particularly limited. For example, a thermal conductive sheet containing a resin and a thermally conductive filler may be cited.

[0076] Examples of thermally conductive fillers include aluminum nitride, aluminum oxide, boron nitride, titanium oxide, zinc oxide, silicon carbide, silicon, silicon oxide, silica, glass, metal particles, carbon fibers, graphite, graphene, carbon nanotubes, etc. The thermally conductive fillers may be surface-treated. One type of thermally conductive filler may be used alone or two or more types may be used in combination.

[0077] The shape of the thermally conductive filler is not particularly limited and may include spherical, ellipsoidal, flaky, granular, rod-shaped, needle-shaped, fibrous, etc.

[0078] The average particle size of the thermally conductive filler is not specifically limited, and it is preferable to set it according to the material of the thermally conductive filler, etc.

[0079] The aspect ratio (major axis / minor axis) of the thermally conductive filler is not specifically limited and may be in the range of 1 to 100, 5 to 50, or 10 to 40. The aspect ratio of the thermally conductive filler is determined by measuring the ratio of the major axis to the minor axis (major axis / minor axis) for each of 20 representative particles using a scanning electron microscope (SEM), and taking the arithmetic mean of the obtained measurements.

[0080] It is preferable that the thermally conductive filler be oriented in the thickness direction of the thermally conductive sheet from the perspective of thermal conductivity. In the present disclosure, "oriented in the thickness direction" means that, in a thermally conductive filler having a major axis and a minor axis (i.e., the aspect ratio exceeds 1), the angle formed between the major axis direction of the thermally conductive filler and the surface (main surface) of the thermally conductive sheet (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.

[0081] The content of the thermal conductive filler in the thermal conductive sheet should be appropriately selected based on the material of the thermal conductive filler, etc., from the perspective of the balance of thermal conductivity and adhesion. For example, the content of the thermal conductive filler may be 25 volume% to 75 volume% with respect to the total volume of the thermal conductive sheet, 30 volume% to 60 volume%, or 35 volume% to 50 volume%.

[0082] The resin contained in the thermal conductive sheet is not particularly limited and may be, for example, a curable resin or a non-curable resin. Examples of resins 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, and hydrogenated terpene phenol. One type of resin may be used alone or two or more types may be used in combination.

[0083] The resin content in the thermal conductive sheet is preferably selected according to the type of resin and the desired flexibility, adhesive strength, adhesion, sheet strength, hydrolytic resistance, etc. For example, the resin content is preferably 25 volume% to 75 volume% with respect to the total volume of the thermal conductive sheet, more preferably 40 volume% to 70 volume%, and even more preferably 50 volume% to 65 volume%.

[0084] In addition to thermally conductive fillers and resins, the thermal conductive sheet may contain various additives such as flame retardants and antioxidants. The flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. Examples include phosphorus-based flame retardants and phosphate ester-based flame retardants. Among these, phosphate ester-based flame retardants are preferred due to their excellent safety and improved adhesion through a plasticizing effect.

[0085] The method of manufacturing the thermal conductive sheet is not particularly limited as long as it is a method that obtains a thermal conductive sheet having the specific compressive modulus and tackiness mentioned above. For example, a composition containing each component of the thermal conductive sheet may be prepared, and the sheet may be manufactured by rolling, pressing, extrusion, coating, etc.

[0086] In addition, a sheet may be produced by forming a molded body using a composition containing each component of a thermal conductive sheet and slicing the molded body. At this time, it is preferable to slice the molded body so that the thermal conductive filler is oriented in the thickness direction.

[0087] In one embodiment, the thermal conductive sheet may be manufactured by preparing a composition containing each component of the thermal conductive sheet, forming the composition into a sheet to obtain a sheet, laminating the sheets to produce a laminate, and slicing the side cross-section of the laminate. By manufacturing the thermal conductive sheet in this way, an efficient thermal conduction path is formed, and a thermal conductive sheet with excellent thermal conductivity and adhesion tends to be obtained. Additionally, the obtained thermal conductive sheet may be laminated by attaching it to a protective film.

[0088] [Method of bonding heating element and heat dissipation element]

[0089] In the method for manufacturing a semiconductor device according to the present disclosure, a heat-conducting sheet is disposed between a heating element and a heat-dissipating element, and pressure is applied in the thickness direction of the heat-conducting sheet to bond the heating element and the heat-dissipating element with the heat-conducting sheet interposed therebetween.

[0090] In the present disclosure, adhesion refers to a state in which multiple surfaces are in contact by chemical or physical force or both. According to the method for manufacturing a semiconductor device in the present disclosure, there is a tendency to maintain a good adhesion area between a heating element and a heat-conducting sheet, between a heat dissipating element and a heat-conducting sheet, or between both. When a semiconductor device is assembled by adhering a heating element and a heat dissipating element with a heat-conducting sheet interposed therebetween, the adhesion area is preferably 80% or more of the surface area of ​​the heating element or heat dissipating element facing the heat-conducting sheet, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0091] As a method of placing a heat-conducting sheet between a heating element and a heat-dissipating element, the heat-conducting sheet may first be placed on the heating element and then the heat-dissipating element may be placed with the heat-conducting sheet interposed therein, or the heat-conducting sheet may first be placed on the heat-dissipating element and then the heating element may be placed with the heat-conducting sheet interposed therein.

[0092] For one heat-conducting sheet, there may be one heating element and one heat dissipating element, and either one or both of the heating element or the heat dissipating element may be multiple.

[0093] For a heating element and a heat dissipator placed between a heat conductive sheet, pressure is applied in the thickness direction of the heat conductive sheet to bond the heating element and the heat dissipator with the heat conductive sheet in between. At this time, pressure may be applied from the heating element side or from the heat dissipator side.

[0094] The pressure applied in the thickness direction of the thermal conductive sheet is preferably 0.05 MPa to 10.00 MPa, more preferably 0.10 MPa to 5.00 MPa, and even more preferably 0.10 MPa to 1.00 MPa, from the perspective of the adhesion of the thermal conductive sheet and the reduction of the load on electronic components. From the perspective of the reduction of the load on electronic components, it is particularly preferable to be 0.10 MPa to 0.50 MPa. From the perspective of ensuring the adhesion of the thermal conductive sheet, the pressure may be adjusted according to the thickness of the thermal conductive sheet. For example, when the thickness of the thermal conductive sheet is 200 μm or more, the pressure may be 0.20 MPa or less, and when the thickness of the thermal conductive sheet is less than 200 μm, the pressure may be greater than 0.20 MPa.

[0095] The temperature at which pressure is applied is not specifically limited, and it is desirable to select a suitable temperature range depending on the type of heat-conducting sheet. The temperature at which pressure is applied may be room temperature, but it is desirable to be a heated temperature from the perspective of improving compressibility. As for the heated temperature, for example, it may be 80°C to 200°C, 100°C to 190°C, or 120°C to 180°C.

[0096] Among these, it is preferable to apply a pressure of 0.10 MPa to 1.00 MPa within a temperature range of 120℃ to 180℃. Excellent adhesion tends to be obtained by applying a pressure of 0.10 MPa or higher or a heating temperature of 120℃ or higher. Additionally, adhesion reliability tends to be further improved by applying a pressure of 1.00 MPa or lower or a heating temperature of 180℃ or lower. This is believed to be because it prevents the thermal conductive sheet from being excessively compressed and becoming thin, or from causing excessive deformation of surrounding components or residual stress.

[0097] When pressure is applied, for example, when a pressure of 0.10 MPa is applied at 150°C, the amount of bending of the heating element may be, for example, 10 μm or more, 20 μm or more, or 25 μm or more. In addition, when pressure is applied, for example, when a pressure of 0.10 MPa is applied at 150°C, the amount of bending of the heating element may be 80 μm or less, 70 μm or less, or 60 μm or less. The amount of bending of the heating element when a pressure of 0.15 MPa is applied at 150°C may be within the above range.

[0098] The amount of bending of the heating element after releasing the pressure may, for example, be 40 μm or more, 50 μm or more, or 60 μm or more. Additionally, the amount of bending of the heating element after releasing the pressure may be 150 μm or less, 140 μm or less, or 130 μm or less. If the amount of bending changes according to a change in temperature after releasing the pressure, the "amount of bending of the heating element after releasing the pressure" shall be the amount of bending at 25℃.

[0099] In the process of bonding a heating element and a heat dissipating element, the difference between the amount of bending of the heating element when pressure is applied and the amount of bending of the heating element after the pressure is released may be 30 μm or more, 40 μm or more, or 45 μm or more. In addition, the upper limit of the above difference may be, for example, 120 μm or less.

[0100] The "bending amount" of a heating element refers to the maximum deformation amount (μm) in the thickness direction of the heating element when it is bent and deformed.

[0101] An example of a method for measuring the amount of bending when a thermal conductive sheet is used for TIM1 is explained using FIG. 2. The amount of bending can be measured based on the amount of deformation of a substrate equipped with a heating element as follows. The range of analysis for the amount of bending is defined as the part (heating element part) (a) where the heating element is mounted when viewed from the substrate side. In the heating element part (a), the amount of bending (b) is defined as the difference in displacement between the part with the largest amount of deformation in the thickness direction of the substrate and the end of the heating element.

[0102] The greater the amount of bending, the easier it is for the heat-conducting sheet to peel off from the heating element and the heat dissipating element when bending occurs. The heat-conducting sheet used in the present disclosure tends to maintain a good adhesive area without peeling off from the heating element and the heat dissipating element even when the amount of bending of the heating element is large.

[0103] A specific method for bonding a heating element and a heat dissipating element with the heat conductive sheet interposed therebetween is not particularly limited as long as it is a method that can fix them while they are in sufficient close contact. For example, a heat conductive sheet may be placed between the heating element and the heat dissipating element, and the heating element may be heated in this state by a jig capable of applying pressure of 0.05 MPa to 1.00 MPa, or heated by an oven or the like. Additionally, a method may be used by using a press machine capable of applying heat and pressure of 80°C to 180°C and 0.05 MPa to 1.00 MPa.

[0104] For fixing, in addition to clips, jigs such as screws and springs may be used, and it is preferable to further secure them using commonly used means such as adhesives to maintain close contact.

[0105] As described above, the semiconductor device can be manufactured using a heating element and a heat dissipation element bonded via a thermal conductive sheet. The type of semiconductor device is not particularly limited, and examples include electronic materials equipped with integrated circuits (ICs) such as CPUs and memory. Additionally, examples include power devices such as bipolar transistors, power MOSFETs, and IGBTs.

[0106] ≪Method for Manufacturing a Thermal Conductive Sheet≫

[0107] In one embodiment of the present disclosure, regarding a heating element and a heat dissipating element disposed between a heat conductive sheet, a heat conductive sheet is applied while heating in the thickness direction of the heat conductive sheet to bond the heating element and the heat dissipating element with the heat conductive sheet interposed therebetween, and the compression ratio and thickness of the heat conductive sheet may be selected such that the compression amount of the heat conductive sheet satisfies the following formula.

[0108] Formula: C>L2-L1

[0109] L1: Predicted amount of bending (μm) of the heating element when heated and pressurized

[0110] L2: Predicted amount of warping (μm) of the heating element when cooled to 25℃ after terminating heating and pressurization

[0111] C: Predicted compression amount (μm) of the heat conductive sheet under heating and pressurizing conditions

[0112] C = Thickness of the heat-conducting sheet before pressurization (μm) × Compression ratio under heating and pressurization conditions (%)

[0113] The predicted amount of bending (L1) of the heating element when heated and pressurized refers to the predicted amount of bending of the heating element under predicted pressure and temperature conditions. For example, when it is predicted that the heating element and the heat dissipator will be bonded with a heat conductive sheet interposed by applying a pressure of 150°C and 0.10 MPa, it refers to the predicted amount of bending under the condition of applying a pressure of 150°C and 0.10 MPa. In addition, when it is predicted that the heating element and the heat dissipator will be bonded with a heat conductive sheet interposed by applying a pressure of 150°C and 0.15 MPa, it refers to the predicted amount of bending under the condition of applying a pressure of 150°C and 0.15 MPa.

[0114] The predicted amount of bending (L1) of the heating element when heated and pressurized may be, for example, 10 μm or more, 20 μm or more, or 25 μm or more. In addition, the predicted amount of bending (L1) of the heating element when heated and pressurized may be 80 μm or less, 70 μm or less, or 60 μm or less.

[0115] The predicted amount of warping (L2) of the heating element when cooled to 25°C after the heating pressurization is terminated may be, for example, 40 μm or more, 50 μm or more, or 60 μm or more. Additionally, the predicted amount of warping (L2) of the heating element when cooled to 25°C after the heating pressurization is terminated may be 150 μm or less, 140 μm or less, or 130 μm or less.

[0116] The difference between L1 and L2 (L2-L1) may be 30 μm or more, 40 μm or more, or 45 μm or more. In addition, the upper limit of the difference may be, for example, 120 μm or less.

[0117] The predicted amount of compression (C) of the heat-conducting sheet under heating and pressurizing conditions refers to the amount of compression of the heat-conducting sheet under predicted pressure and temperature conditions. For example, when it is predicted that a heating element and a heat dissipator will be bonded with the heat-conducting sheet interposed by applying a pressure of 150°C and 0.10 MPa, it refers to the amount of compression under conditions of 150°C and 0.10 MPa. In addition, when it is predicted that a heating element and a heat dissipator will be bonded with the heat-conducting sheet interposed by applying a pressure of 150°C and 0.15 MPa, it refers to the amount of compression under conditions of 150°C and 0.15 MPa.

[0118] The predicted compression amount (C) of the heat-conducting sheet under heating and pressurizing conditions may be, for example, 20 μm to 1000 μm, 30 μm to 200 μm, or 40 μm to 100 μm.

[0119] The thickness of the heat conductive sheet before pressurization refers to the average thickness of the heat conductive sheet before pressurization. The preferred range for the thickness of the heat conductive sheet is as described above.

[0120] The desirable range of the compression ratio of the thermal conductive sheet is as described above.

[0121] It is believed that the heat conductive sheet manufactured by selecting the compression ratio and thickness as described above has sufficient compression to follow the change in the amount of bending of the heating element during the process of bonding the heating element and the heat dissipating element, so the delamination of the heat conductive sheet is appropriately suppressed.

[0122] Examples

[0123] The present invention will be described in detail below by way of examples, but the present invention is not limited to these examples. In addition, in each example, the evaluation of compressive elasticity modulus, compression amount, tack strength, thermal conductivity, bending amount, and adhesive area was performed by the following method.

[0124] (Measurement of compressive modulus and amount of compression)

[0125] For the measurement, a compression test device (INSTRON 5948 Micro Tester (INSTRON)) equipped with a constant temperature bath was used. A thermal conductive sheet was cut into a circular shape with a diameter of 14 mm and used for the test. The thermal conductive sheet was placed on a 0.1 mm thick paper (release liner), and a load was applied at a displacement rate of 0.1 mm / min in the thickness direction of the thermal conductive sheet at a temperature of 150°C in the constant temperature bath, and the displacement (mm) and load (N) were measured. The deformation (dimensionless) calculated as displacement (mm) / thickness (mm) was plotted on the horizontal axis, and the stress (MPa) calculated as load (N) / area (mm²) was plotted on the vertical axis; the slope at a stress of 0.10 MPa was defined as the compressive modulus (MPa). Additionally, the maximum displacement when compressed to an arbitrary pressure was defined as the amount of compression (μm).

[0126] (Measurement of Tactical Power)

[0127] Using a universal physical property tester (texture analyzer (Eco Seiki Co., Ltd.)), a probe with a diameter of 7 mm was pressed firmly against a heat conductive sheet with a load of 40 N at 25°C (room temperature) for 10 seconds, and then the area obtained by integrating the load and displacement curve when the probe was pulled up was defined as the tactile force (N·mm).

[0128] (Measurement of thermal conductivity)

[0129] A thermal conductive sheet was cut into 10 mm by 10 mm and placed between a heating element, a transistor (2SC2233), and a heat dissipation element, a copper block. When current was passed through the transistor while pressing it at 80°C and a pressure of 0.14 MPa, the transistor temperature T1 (°C) and the copper block temperature T2 (°C) were measured. From the measured values ​​and the applied power W1 (W), the thermal resistance value X (K·cm² / W) per unit area (1 cm²) was calculated as follows.

[0130] X=(T1-T2)×1 / W1

[0131] In addition, the thermal conductivity λ (W / (m·K)) was calculated as follows using the thermal resistance value (K·㎠ / W) and thickness t (μm).

[0132] λ=(t×10 -6 ) / (X×10 -4 )

[0134] *(Measurement of bending amount)

[0135] The amount of warping was measured using a 3D heated surface shape measuring device (Thermoray PS200, AKROMETRIX). The amount of warping of the substrate corresponding to the chip area (20 mm × 20 mm) was measured.

[0136] The amount of warping of the substrate in the chip area at 150°C, which is the assembly condition of the package, was 29 μm. In addition, the amount of warping of the substrate in the chip area at 25°C after assembly was 75 μm. Therefore, the difference in the amount of warping was 46 μm.

[0137] (Adhesion Area Evaluation Test)

[0138] The adhesion area was evaluated as follows. Using an ultrasonic imaging diagnostic device (Insight-300, Insight Co., Ltd.), the adhesion status was observed under the reflection method at 35 MHz. In addition, the image was binarized using image analysis software (ImageJ), and the ratio of the adhesion area to the chip portion of 20 mm by 20 mm was calculated and set as the adhesion area (%).

[0139] For the adhesion area evaluation test, a simple package prepared as follows was used.

[0140] MCL-E-700G(R) (thickness 0.81 mm, Hitachi Kasei Co., Ltd.) was used for the substrate, CEL-C-3730N-2 (Hitachi Kasei Co., Ltd.) was used for the underfill material, and a silicone-based adhesive (SE4450, Toray Dow Corning Co., Ltd.) was used for the seal material. In addition, a 1 mm thick copper plate with a nickel-plated surface was used for the heat spreader. The dimensions of the substrate and heat spreader were set to 45 mm by 45 mm, and the semiconductor chip dimensions were set to 20 mm by 20 mm. At this time, the bending amount of the heating element was 29 μm when a pressure of 0.15 MPa at 150°C was applied, and the bending amount of the heating element was 75 μm when the pressure was released and the temperature was cooled to 25°C.

[0141] The assembly of the package was carried out as follows. A thermal conductive sheet of arbitrary thickness was cut into 23 mm x 23 mm pieces and attached to a heat spreader. A semiconductor chip was placed on the heat spreader with the thermal conductive sheet interposed therebetween. Using a high-precision pressure and heat bonding device (HTB-MM, Alpha Design Co., Ltd.), pressure was applied in the thickness direction of the thermal conductive sheet for 3 minutes at an arbitrary temperature and pressure. Subsequently, the sealing material was completely cured by treating it in a constant temperature bath at 150°C for 2 hours.

[0142] <Example 1>

[0143] A 0.3 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.16 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 7.6 N·mm at 25°C, and a thermal conductivity of 21 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.15 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipation element. At this time, the bonding area was 99%. The bonding area, which is an indicator of bending followability, was 90% or more, demonstrating excellent bending followability. The compression ratio of the thermal conductive sheet under compression at 150°C and 0.15 MPa was 19%, and the compression amount of the thermal conductive sheet was 57 μm.

[0144] <Example 2>

[0145] A 0.2 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.16 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 7.6 N·mm at 25°C, and a thermal conductivity of 18 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.15 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipation element. At this time, the bonding area was 95%. The bonding area, which is an indicator of bending followability, was 90% or more, indicating excellent bending followability. The compression ratio of the thermal conductive sheet under compression at 150°C and 0.15 MPa was 21%, and the compression amount of the thermal conductive sheet was 47 μm.

[0146] <Example 3>

[0147] A 0.15 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.16 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 7.6 N·mm at 25°C, and a thermal conductivity of 16 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.31 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipator. At this time, the bonding area was 90%. The compression ratio of the thermal conductive sheet at 150°C and 0.31 MPa was 35%, and the compression amount of the thermal conductive sheet was 52 μm.

[0148] <Comparative Example 1>

[0149] As a thermal conductive material, liquid silicone grease (manufactured by Sanwa Supply, TK-P3K) with a thermal conductivity of 2 W / (m·K) was selected, and a package was assembled using the above method under conditions of 150°C and 0.03 MPa to bond to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipation element. In addition, since it is in a liquid state, the compressive modulus and tack force cannot be measured. After assembly, the thickness of the silicone grease was 40 μm, and the bonding area was 63%.

[0150] <Comparative Example 2>

[0151] A 0.3 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.44 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 7.2 N·mm at 25°C, and a thermal conductivity of 20 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.15 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipator. At this time, the bonding area was 72%. The compression ratio of the thermal conductive sheet at 150°C and 0.15 MPa was 13%, and the compression amount of the thermal conductive sheet was 40 μm.

[0152] <Comparative Example 3>

[0153] A 0.3 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.73 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 1.8 N·mm at 25°C, and a thermal conductivity of 23 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.15 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipator. At this time, the bonding area was 74%. The compression ratio of the thermal conductive sheet under compression at 150°C and 0.15 MPa was 13%, and the compression amount of the thermal conductive sheet was 44 μm.

[0154] <Comparative Example 4>

[0155] A 0.3 mm thick thermal conductive sheet manufactured by Hitachi Kasei Co., Ltd. was selected, having a compressive modulus of 1.35 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 3.8 N·mm at 25°C, and a thermal conductivity of 18 W / (m·K). A package was assembled using the above method under conditions of 150°C and 0.15 MPa, and the thermal conductive sheet was bonded to a semiconductor chip, which is a heating element, and a heat spreader, which is a heat dissipator. At this time, the bonding area was 78%. The compression ratio of the thermal conductive sheet under compression at 150°C and 0.15 MPa was 16%, and the compression amount of the thermal conductive sheet was 48 μm.

[0156] As described above, when a heating element and a heat dissipation element are bonded using the method of the example, the bonding area could be maintained well. Thus, it is believed that a semiconductor device with excellent heat dissipation properties can be obtained.

[0157] All documents, patent applications, and technical specifications described in this specification are incorporated by reference into this specification to the same extent as individual documents, patent applications, and technical specifications are incorporated by reference as they are specifically and individually described. Explanation of the symbols

[0158] 1: Thermal conductive sheet 2: Semiconductor chip (heating element) 3: Heat spreader (heat sink) 4: Substrate 5: Underfill material 6: Siiljae a: Heating element part (interpretation range) b: Bending amount

Claims

Claim 1 A method for manufacturing a semiconductor device, comprising a process of applying pressure in the thickness direction of a heat-conducting sheet to a heating element and a heat dissipating element disposed between a heat-conducting sheet, wherein the heat-conducting sheet has a compressive elastic modulus of 0.50 MPa to 1.40 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 5.0 N·mm or more at 25°C, and a compression ratio of 15% to 60% when the compressive stress at 150°C is 0.10 MPa, and thereby bonding the heating element and the heat dissipating element with the heat-conducting sheet interposed therebetween. Claim 2 A method for manufacturing a semiconductor device according to claim 1, wherein the thermal conductivity of the thermal conductive sheet obtained from the thermal resistance measured by the normal method is 7 W / (m·K) or higher. Claim 3 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the pressure is 0.05 MPa to 10.00 MPa. Claim 4 A method for manufacturing a semiconductor device according to claim 3, wherein the pressure is 0.10 MPa to 0.50 MPa. Claim 5 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the heating element is a semiconductor chip and the heat dissipation element is a heat spreader. Claim 6 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the surface area of ​​the heating element facing the heat-conducting sheet is 25 mm² or more. Claim 7 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the heating element is a semiconductor package having a heat spreader and the heat dissipation element is a heat sink. Claim 8 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the heating element is a semiconductor module. Claim 9 A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the surface area of ​​the heating element facing the heat-conducting sheet is 100 mm² or more. Claim 10 A heat-conducting sheet having a compressive elastic modulus of 0.50 MPa to 1.40 MPa when the compressive stress at 150°C is 0.10 MPa, a tack force of 5.0 N·mm or more at 25°C, and a compressibility of 15% to 60% when the compressive stress at 150°C is 0.10 MPa. The sheet is disposed between a heating element and a heat sink of a semiconductor device and used for bonding the heating element and the heat sink. Claim 11 A thermally conductive sheet according to claim 10, wherein the thermal conductivity obtained from the thermal resistance measured by the normal method is 7 W / (m·K) or higher. Claim 12 A heat-conducting sheet according to claim 10 or 11, wherein the heating element is a semiconductor chip and the heat dissipation element is a heat spreader. Claim 13 A heat-conducting sheet according to claim 10 or 11, wherein the heating element is a semiconductor package having a heat spreader, and the heat dissipation element is a heat sink. Claim 14 A heat-conducting sheet according to claim 10 or 11, wherein the heating element is a semiconductor module.

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