Method for producing composite sheet, composite sheet, bonding method, and bonded body

Abstract

In this method for producing a composite sheet, particles are arranged on a surface of a sheet layer formed in a sheet shape, and pressure is applied in the thickness direction of the sheet layer, so that the particles are embedded in the sheet layer. In a method for producing another composite sheet, particles are arranged on a surface of a first sheet layer that is formed in a sheet shape and forms a part of a sheet layer, a second sheet layer that is formed in a sheet shape and forms a part of the sheet layer is disposed on the surface of the first sheet layer where the particles are arranged, and pressure is applied to the first sheet layer and the second sheet layer in an opposing direction between the first sheet layer and the second sheet layer, so that the particles are embedded in at least one of the first sheet layer and the second sheet layer. The composite sheet contains particles in the sheet layer, and the particles are distributed only within a certain range in the thickness direction of the sheet layer. The other composite sheet contains particles in the sheet layer, and the particles are arranged in a single layer such that the particles do not overlap in the thickness direction of the sheet layer.

Description

Composite sheet manufacturing method, composite sheet, joining method, and joined body

[0001] The present disclosure relates to a method for manufacturing a composite sheet, a composite sheet, a joining method, and a joined body.

[0002] A coating method is widely used as a method for producing a composite sheet containing particles or the like in a resin sheet layer (see, for example, Patent Document 1). This coating method involves dispersing particles in a coating liquid, applying the coating liquid containing the dispersed particles, and heating and drying the applied coating liquid.

[0003] Japanese Patent Application Laid-Open No. 2023-121118

[0004] When producing a composite sheet by coating, the particle positions in the coating liquid become irregular and the particles aggregate in the coating liquid, making it difficult to control the particle positions in the sheet layer. If the particle positions in the sheet layer cannot be controlled, the bonding characteristics of the bonded body bonded using the composite sheet may be insufficient. The bonding characteristics include bonding strength, inclination of the bonded bodies, thermal or electrical conductivity, etc.

[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing a composite sheet, a composite sheet, a joining method, and a joined body that can control the position of particles in a sheet layer to obtain high joining properties.

[0006] [1] A method for manufacturing a composite sheet according to the present disclosure is a method for manufacturing a composite sheet in which particles are contained in a sheet layer, in which particles are arranged on the surface of a sheet layer formed into a sheet shape, and pressure is applied in the thickness direction of the sheet layer to embed the particles in the sheet layer.

[0007] In this composite sheet manufacturing method, particles are placed on the surface of a sheet layer formed into a sheet shape, and pressure is applied in the thickness direction of the sheet layer to embed the particles into the sheet layer. This makes it possible to control the position of the particles in the sheet layer more easily than in a composite sheet manufacturing method in which particles are dispersed in a coating liquid. As a result, high bonding properties can be obtained by bonding objects to be bonded using the manufactured composite sheet.

[0008] [2] Another method for producing a composite sheet according to the present disclosure is a method for producing a composite sheet having particles contained in sheet layers, comprising: arranging particles on the surface of a first sheet layer formed into a sheet shape and constituting a part of the sheet layer; arranging a second sheet layer formed into a sheet shape and constituting a part of the sheet layer on the surface of the first sheet layer on which the particles are arranged; and applying pressure to the first sheet layer and the second sheet layer in a direction opposite to the first sheet layer and the second sheet layer to embed the particles in at least one of the first sheet layer and the second sheet layer.

[0009] In this composite sheet manufacturing method, particles are disposed on the surface of a first sheet layer formed into a sheet shape, a second sheet layer formed into a sheet shape is disposed on the surface of the first sheet layer on which the particles are disposed, and pressure is applied to the first and second sheet layers in the opposing direction of the first and second sheet layers to embed the particles in at least one of the first and second sheet layers. This makes it possible to control the position of the particles in the sheet layers more easily than in a method of manufacturing a composite sheet by dispersing particles in a coating liquid. As a result, high bonding properties can be obtained by bonding objects to be bonded using the manufactured composite sheet.

[0010] [3] In the method for producing a composite sheet according to [1] or [2], the particles may be distributed only within a certain range in the thickness direction of the sheet layer. In this method for producing a composite sheet, the particles are distributed only within a certain range in the thickness direction of the sheet layer. By using the produced composite sheet to bond objects, it becomes easier to control the separation distance between the objects. As a result, for example, the separation distance between the objects can be maintained within the thickness range of the sheet layer in which the particles are distributed.

[0011] [4] In the method for producing a composite sheet according to any one of [1] to [3], the particles may have a maximum length equal to or greater than half the thickness of the sheet layer. In this method for producing a composite sheet, the particles have a maximum length equal to or greater than half the thickness of the sheet layer, so that when the produced composite sheet is used to bond objects to each other, the particles can be easily brought into contact with the objects to be bonded.

[0012] [5] In the method for producing a composite sheet according to any one of [1] to [4], the particles may be arranged in a single layer that does not overlap in the thickness direction of the sheet layer. This method for producing a composite sheet allows for the production of a thin composite sheet, since the particles are arranged in a single layer that does not overlap in the thickness direction of the sheet layer. This allows for the production of a composite sheet with a thickness equal to, for example, the primary particle diameter of the particles. Furthermore, by using the produced composite sheet to bond objects, it becomes easier to control the separation distance between the objects. This allows, for example, the separation distance between the objects to be bonded to be maintained at the thickness equal to the primary particle diameter of the particles.

[0013] [6] In the method for producing a composite sheet according to [5], the particles may be regularly arranged. In this method for producing a composite sheet, since the particles are regularly arranged, a composite sheet suitable for bonding to regularly arranged bonded parts can be produced.

[0014] [7] In the method for producing a composite sheet according to any one of [1] to [6], the particles may have at least one of thermal and electrical conductivity greater than that of the sheet layer, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer may be greater than 15%. In this method for producing a composite sheet, particles having at least one of thermal and electrical conductivity greater than that of the sheet layer are used, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer is greater than 15%, so that the conductivity of at least one of thermal and electrical conductivity of the composite sheet as a whole can be improved.

[0015] [8] In the method for producing a composite sheet according to any one of [1] to [7], the thickness of the sheet layer may be equal to or less than the maximum length of the particles. In this method for producing a composite sheet, the thickness of the sheet layer is equal to or less than the maximum length of the particles, so that a composite sheet can be produced in which the particles are exposed from the sheet layer. As a result, by joining objects to be joined using the produced composite sheet, the particles can be brought into direct contact with the objects to be joined without the intermediary of the sheet layer.

[0016] [9] In the method for producing a composite sheet according to any one of [1] to [8], the particles may be exposed from the sheet layer. In this method for producing a composite sheet, the particles are exposed from the sheet layer, and by bonding objects to be bonded using the produced composite sheet, the particles can be brought into direct contact with the objects to be bonded without the intermediary of the sheet layer.

[0017]

[10] In the method for producing a composite sheet according to any one of [1] to [9], the surfaces of the particles may be solder. In this method for producing a composite sheet, since the surfaces of the particles are solder, when the produced composite sheet is used to join objects to be joined, by melting the solder, it is possible to increase the thermal and electrical conductivity between the objects to be joined and also increase the joining strength between the objects to be joined.

[0018]

[11] In the method for producing a composite sheet according to any one of [1] to

[10] , the surfaces of the particles may be metallic. In this method for producing a composite sheet, since the surfaces of the particles are metallic, by using the produced composite sheet to bond objects, it is possible to increase the thermal and electrical conductivity between the objects to be bonded.

[0019]

[12] In the composite sheet manufacturing method according to

[10] or

[11] , the sheet layer may contain a flux component. In this composite sheet manufacturing method, the particle surfaces are solder or metal, so the particle surfaces are covered with an oxide film. However, since the sheet layer contains a flux component, the oxide film can be removed by the flux component. This allows for high bonding properties to be obtained.

[0020]

[13] In the method for producing a composite sheet according to any one of [1] to

[12] , the sheet layer may contain a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application. In this method for producing a composite sheet, the sheet layer contains a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application. Therefore, when bonding objects to be bonded using the produced composite sheet, the sheet layer can be bonded to the objects to be bonded by applying pressure, heat, or ultrasonic wave to the sheet layer.

[0021]

[14] The composite sheet according to the present disclosure is a composite sheet in which particles are contained in a sheet layer, and the particles are distributed only within a certain range in the thickness direction of the sheet layer.

[0022] In this composite sheet, the particles are distributed only within a certain range in the thickness direction of the sheet layer, which prevents the objects from tilting when bonded, resulting in high bonding properties.

[0023]

[15] Another composite sheet according to the present disclosure is a composite sheet in which particles are contained in a sheet layer, and the particles are arranged in a single layer that does not overlap in the thickness direction of the sheet layer.

[0024] In this composite sheet, the particles are arranged in a single layer without overlapping in the thickness direction of the sheet layer, which reduces the tilt between the objects to be joined, resulting in high joining characteristics.

[0025]

[16] In the composite sheet according to

[15] , the thickness of the sheet layer may be equal to or less than the maximum length of the particles. In this composite sheet, the thickness of the sheet layer is equal to or less than the maximum length of the particles, so the thickness of the composite sheet can be set to the maximum length of the particles. This allows the composite sheet to be thin. Furthermore, since the thickness of the sheet layer is equal to or less than the maximum length of the particles, the particles are exposed from the sheet layer. This allows the particles to come into direct contact with the objects to be joined without the intermediary of the sheet layer, thereby improving the bonding characteristics between the particles and the objects to be joined.

[0026]

[17] In the composite sheet according to

[15] or

[16] , the particles may be exposed from the sheet layer. In this composite sheet, since the particles are exposed from the sheet layer, the particles can be brought into direct contact with the object to be joined without the intermediary of the sheet layer.

[0027]

[18] In the composite sheet according to any one of

[15] to

[17] , the particles may be regularly arranged. Since the particles are regularly arranged in this composite sheet, the composite sheet is suitable for bonding to a regularly arranged bonded part.

[0028]

[19] In the composite sheet according to any one of

[14] to

[18] , the maximum length of the particles may be equal to or greater than half the thickness of the sheet layer. In this composite sheet, since the maximum length of the particles is equal to or greater than half the thickness of the sheet layer, when bonding objects to be bonded, the particles can be easily brought into contact with the objects to be bonded.

[0029]

[20] In the composite sheet according to any one of

[14] to

[19] , the particles may have at least one of thermal and electrical conductivity greater than that of the sheet layer, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer may be greater than 15%. In this composite sheet, particles having at least one of thermal and electrical conductivity greater than that of the sheet layer are used, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer is greater than 15%, so that the conductivity of at least one of thermal and electrical conductivity of the composite sheet as a whole can be improved.

[0030]

[21] In the composite sheet according to any one of

[14] to

[20] , the surfaces of the particles may be solder. In this composite sheet, since the surfaces of the particles are solder, by melting the solder, it is possible to increase the thermal and electrical conductivity between the objects to be joined and to increase the bonding strength between the objects to be joined.

[0031]

[22] In the composite sheet according to any one of

[14] to

[21] , the particle surfaces may be metallic. In this composite sheet, the metallic particle surfaces can improve the thermal and electrical conductivity between the objects to be joined.

[0032]

[23] In the composite sheet according to

[21] or

[22] , the sheet layer may contain a flux component. In this composite sheet, the surface of the particles is solder or metal, so the particles are covered with an oxide film. However, since the sheet layer contains a flux component, the oxide film can be removed by the flux component. This allows for high bonding properties to be obtained.

[0033]

[24] In the composite sheet according to any one of

[14] to

[23] , the sheet layer may contain a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application. In this composite sheet, since the sheet layer contains a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application, the sheet layer can be used to bond objects by applying pressure, heat, or ultrasonic waves to the sheet layer.

[0034]

[25] The composite sheet according to any one of

[14] to

[24] may further comprise a second sheet laminated on the particle-containing sheet layer.

[0035]

[26] In the composite sheet according to

[25] , the sheet layer may be laminated on at least one of both surfaces of the second sheet.

[0036]

[27] The composite sheet according to any one of

[14] to

[26] may further comprise a third sheet including, as an inner layer, a sheet layer containing particles.

[0037]

[28] The composite sheet according to any one of

[14] to

[27] may be formed by laminating a plurality of particle-containing sheet layers.

[0038]

[29] A bonding method according to the present disclosure includes placing the composite sheet according to any one of

[14] to

[28] between a first object to be bonded and a second object to be bonded, and bonding the first object to be bonded and the second object to be bonded via the composite sheet.

[0039] In this joining method, any of the composite sheets described above is placed between the first and second objects to be joined, and the first and second objects to be joined are joined via the composite sheet, so that a joined body with high joining properties can be obtained.

[0040]

[30] In the bonding method described in

[29] , the surfaces of the particles may be solder. In the bonding step, a composite sheet may be placed between the first and second bonded bodies, and the first and second bonded bodies may be pressed in the direction of their facing, thereby bringing the particles into contact with the first and second bonded bodies. Ultrasonic waves may be applied to at least one of the first and second bonded bodies to remove an oxide film present on the surfaces of the particles. In this bonding method, since the surfaces of the particles are solder, the particles are covered with an oxide film. However, by placing a composite sheet between the first and second bonded bodies and pressing the first and second bonded bodies in the direction of their facing, the particles may be brought into contact with the first and second bonded bodies, and ultrasonic waves may be applied to at least one of the first and second bonded bodies to remove the oxide film present on the surfaces of the particles. Therefore, for example, by performing a subsequent heating step, etc., as necessary, the particles can be easily bonded to the first and second bonded bodies.

[0041]

[31] In the bonding method according to

[30] , the first and second objects to be bonded may have metal bonded portions, and in the bonding step, an oxide film present on the surface of the bonded portions may be removed by applying ultrasonic waves to at least one of the first and second objects to be bonded while bringing the particles into contact with the bonded portions of the first and second objects to be bonded. In this bonding method, an oxide film present on the surface of the particles is removed by applying ultrasonic waves to at least one of the first and second objects to be bonded while bringing the particles into contact with the bonded portions of the first and second objects to be bonded. Therefore, for example, by subsequently performing a heating step or the like as necessary, the particles can be easily bonded to the bonded portions of the first and second objects to be bonded.

[0042]

[32] In the bonding method according to

[30] or

[31] , the bonding step may involve applying ultrasonic waves to at least one of the first and second objects to be bonded to melt the solder and bond the particles to the first and second objects to be bonded. In this bonding method, ultrasonic waves are applied to at least one of the first and second objects to be bonded to melt the solder and bond the particles to the first and second objects to be bonded. Therefore, the particles can be bonded to the first and second objects to be bonded without a subsequent heating step.

[0043]

[33] In the bonding method according to any one of

[30] to

[32] , the first and second objects to be bonded may have metal bonded portions, and in the bonding step, ultrasonic waves may be applied to at least one of the first and second objects to be bonded to form clean surfaces on the surfaces of the particles and the surfaces of the bonded portions, and the particles and the bonded portions may be solid-state bonded. In this bonding method, ultrasonic waves may be applied to at least one of the first and second objects to be bonded to form clean surfaces on the surfaces of the particles and the surfaces of the bonded portions, and the particles and the bonded portions may be solid-state bonded. Therefore, the particles and the bonded portions of the first and second objects to be bonded can be bonded without a subsequent heating step.

[0044]

[34] In the bonding method described in

[29] , the surfaces of the particles may be metallic, and the first and second objects to be bonded may have metallic bonded portions. In the bonding step, a composite sheet may be placed between the first and second objects to be bonded, and pressure may be applied to the first and second objects in a direction in which the first and second objects face each other, thereby bringing the particles into contact with the bonded portions of the first and second objects to be bonded. Ultrasonic waves may be applied to at least one of the first and second objects to be bonded to smooth the bonded surfaces between the particles and the bonded portions. In this bonding method, since the surfaces of the particles are metallic, the particles are covered with an oxide film. However, by placing a composite sheet between the first and second objects to be bonded, and pressurizing the first and second objects in a direction in which the first and second objects to be bonded face each other, the particles may come into contact with the bonded portions of the first and second objects to be bonded, and ultrasonic waves may be applied to at least one of the first and second objects to be bonded to smooth the bonded surfaces between the particles and the bonded portions. This increases the contact area between the particles and the parts to be joined, improving the thermal and electrical conductivity between the first and second objects to be joined.

[0045]

[35] In the bonding method according to

[29] , the surfaces of the particles may be metallic, and the first and second objects to be bonded may have metallic bonded portions. In the bonding step, a composite sheet may be placed between the first and second objects to be bonded, and pressure may be applied to the first and second objects to be bonded in a direction in which the first and second objects to be bonded face each other, thereby bringing the particles into contact with the bonded portions of the first and second objects to be bonded, and ultrasonic waves may be applied to at least one of the first and second objects to be bonded to remove oxide films present on the surfaces of the particles and the surfaces of the bonded portions, forming clean surfaces on the surfaces of the particles and the surfaces of the bonded portions, thereby solid-state bonding the particles and the bonded portions. In this bonding method, since the surfaces of the particles and the bonded portions are metallic, the particles and the bonded portions are covered with oxide films. However, by placing a composite sheet between the first and second objects to be bonded and applying pressure to the first and second objects in the direction in which they face each other, the particles come into contact with the bonded portions of the first and second objects to be bonded, and applying ultrasonic waves to at least one of the first and second objects to be bonded removes the oxide films present on the surfaces of the particles and the bonded portions, forming clean surfaces on the surfaces of the particles and the bonded portions, thereby solid-state bonding the particles and the bonded portions. Therefore, the particles can be bonded to the bonded portions of the first and second objects to be bonded without a subsequent heating step. Furthermore, the bonding strength between the particles and the bonded portions of the first and second objects to be bonded can be increased.

[0046]

[36] In the bonding method described in

[29] , the surfaces of the particles may be metallic, the first and second objects to be bonded may have metallic bonded portions, and the sheet layer of the composite sheet may contain a flux component. In the bonding step, the composite sheet may be disposed between the bonded portions of the first and second objects to be bonded and the first and second objects to be bonded are pressed in a direction in which the first and second objects face each other, thereby removing oxide films present on the surfaces of the particles and the surfaces of the bonded portions by the flux component. In this bonding method, since the surfaces of the particles and the surfaces of the objects to be bonded are metallic, the particles and the surfaces of the objects to be bonded are covered with an oxide film. However, by disposing the composite sheet between the bonded portions of the first and second objects to be bonded and pressing the first and second objects to be bonded in a direction in which the first and second objects to be bonded face each other, the oxide films present on the surfaces of the particles and the surfaces of the bonded portions by the flux component are removed. Therefore, for example, by subsequently carrying out a heating step or the like as necessary, the particles and the bonded portions of the first and second bodies to be bonded can be easily bonded to each other.

[0047]

[37] In the bonding method according to

[29] , the surfaces of the particles may be metallic, the first and second objects to be bonded may have metallic bonded portions, and the sheet layer of the composite sheet may contain a flux component. In the bonding step, the composite sheet may be disposed between the bonded portions of the first and second objects to be bonded, and the first and second objects to be bonded may be pressed in a direction in which the first and second objects to be bonded face each other to bring the particles into contact with the bonded portions of the first and second objects to be bonded. The flux component may be used to remove oxide films present on the surfaces of the particles and the surfaces of the bonded portions. Ultrasonic waves may be applied to at least one of the first and second objects to be bonded to remove the oxide films present on the surfaces of the particles and the surfaces of the bonded portions, forming clean surfaces on the surfaces of the particles and the surfaces of the bonded portions, thereby solid-state bonding the particles and the surfaces to be bonded. In this bonding method, since the surfaces of the particles and the surfaces to be bonded are metallic, the surfaces of the particles and the surfaces to be bonded are covered with an oxide film. However, by placing a composite sheet between the bonded portions of the first and second objects and applying pressure to the first and second objects in the direction of facing each other, the particles are brought into contact with the bonded portions of the first and second objects, and the flux components remove the oxide films present on the surfaces of the particles and the bonded portions. Ultrasonic waves are applied to at least one of the first and second objects to be bonded, removing the oxide films present on the surfaces of the particles and the bonded portions, forming clean surfaces, and solid-state bonding between the particles and the bonded portions. This allows the particles to be bonded to the bonded portions of the first and second objects without a subsequent heating step. Furthermore, the bonding strength between the particles and the bonded portions of the first and second objects can be increased.

[0048]

[38] In the bonding method according to any one of

[30] to

[37] , in the bonding step, a flux component may be applied to the surface of at least one of the composite sheet, the first bonded body, and the second bonded body before applying pressure to the first bonded body and the second bonded body. In this bonding method, the flux component is applied to the surface of at least one of the composite sheet, the first bonded body, and the second bonded body before applying pressure to the first bonded body and the second bonded body. This allows the flux component to remove oxide films present on the surfaces of the particles. This allows the output of ultrasonic waves to be reduced. Even if ultrasonic waves are not applied thereafter, the particles can be easily bonded to the first bonded body and the second bonded body by, for example, performing a subsequent heating step as necessary.

[0049]

[39] In the bonding method according to any one of

[30] ,

[31] ,

[32] ,

[33] ,

[35] ,

[37] , and

[38] , in the bonding step, ultrasonic waves may be applied to at least one of the first and second objects to be bonded in a reducing environment. In this bonding method, ultrasonic waves are applied to at least one of the first and second objects to be bonded in a reducing environment, so that the output of the ultrasonic waves can be reduced.

[0050]

[40] In the bonding method according to any one of

[29] to

[39] , the first object to be bonded may have parts to be bonded arranged at specific positions, and the particles may be arranged at positions corresponding to the parts to be bonded. In this bonding method, the first object to be bonded has parts to be bonded arranged at specific positions, and the particles are arranged at positions corresponding to the parts to be bonded, so that the first object to be bonded and the second object to be bonded can be easily bonded to the particles.

[0051]

[41] In the bonding method described in

[29] , the first and second objects to be bonded may have bonded portions with recesses formed therein, the particles being arranged at positions corresponding to the recesses and being larger than the recesses, and in the bonding step, a composite sheet may be placed between the bonded portions of the first and second objects to be bonded and the first and second objects to be bonded are pressed in a direction in which the first and second objects to be bonded face each other, thereby forcing the particles into the recesses. In this bonding method, the first and second objects to be bonded may have bonded portions with recesses formed therein, the particles being arranged at positions corresponding to the recesses and being larger than the recesses, the composite sheet may be placed between the bonded portions of the first and second objects to be bonded and the first and second objects to be bonded are pressed in a direction in which the first and second objects to be bonded face each other, thereby forcing the particles into the recesses. Therefore, the bonding strength between the particles and the first and second objects to be bonded may be increased by the pressure between the particles and the recesses and the stress due to compressive deformation of the particles and the recesses.

[0052]

[42] In the bonding method described in

[29] , the first and second objects to be bonded have bonded portions with recesses formed therein, the particles are arranged at positions corresponding to the recesses and are smaller than the recesses, the thermal expansion coefficient of the particles is larger than the linear expansion coefficient of the bonded portions of the first and second objects to be bonded, the surfaces of the particles and the surfaces of the recesses are metallic, and in the bonding step, a composite sheet may be arranged between the bonded portions of the first and second objects to be bonded and the particles are inserted into the recesses, and the first and second objects to be bonded are heated while being pressurized in a direction in which the first and second objects to be bonded face each other, thereby diffusion bonding the particles and the recesses. In this bonding method, the first and second bodies to be bonded have bonded portions with recesses formed therein, particles are arranged at positions corresponding to the recesses and are smaller than the recesses, the particles have a thermal expansion coefficient greater than the linear expansion coefficient of the bonded portions of the first and second bodies to be bonded, the surfaces of the particles and the recesses are metallic, a composite sheet is placed between the bonded portions of the first and second bodies to be bonded, the particles are inserted into the recesses, and the first and second bodies to be bonded are heated while being pressurized in a direction in which the first and second bodies to be bonded face each other, thereby diffusion bonding the particles and the recesses. This increases the bonding strength between the particles and the first and second bodies to be bonded.

[0053]

[43] The bonding method according to any one of

[29] to

[42] may further include an inspection step of inspecting the composite sheet before the bonding step, wherein in the bonding step, the first and second bonded bodies are not bonded using a composite sheet determined to be defective in the inspection step, and the first and second bonded bodies are bonded using a composite sheet determined to be non-defective in the inspection step. In this bonding method, the composite sheet is inspected before the bonding step, and the first and second bonded bodies are not bonded using a composite sheet determined to be defective, and the first and second bonded bodies are bonded using a composite sheet determined to be non-defective. This makes it possible to reduce the occurrence of defective bonded bodies.

[0054]

[44] In the bonding method according to

[43] , the first bonded body may have bonded parts arranged in specific positions, the particles may be arranged in positions corresponding to the bonded parts, and the inspection step may include visual inspection of the particle arrangement. In this bonding method, the first bonded body may have bonded parts arranged in specific positions, the particles may be arranged in positions corresponding to the bonded parts, and the inspection step may include visual inspection of the particle arrangement. This makes it possible to prevent the generation of defective bonded bodies due to poor particle arrangement.

[0055]

[45] In the bonding method according to

[43] or

[44] , in the bonding step, a first bonded object may be bonded to a composite sheet determined to be non-defective in the inspection step, and then a second bonded object may be bonded to the surface of the composite sheet opposite to the first bonded object. In this bonding method, the first bonded object is bonded to a composite sheet determined to be non-defective, and then a second bonded object is bonded to the surface of the composite sheet opposite to the first bonded object. This makes it possible to easily bond the first bonded object and the second bonded object.

[0056]

[46] A bonded structure according to the present disclosure includes a first body to be bonded and a second body to be bonded joined via the composite sheet according to any one of

[14] to

[28] . In this bonded structure, the first body to be bonded and the second body to be bonded are joined via any one of the composite sheets described above, and therefore high bonding properties can be obtained.

[0057] According to the present disclosure, the position of particles in the sheet layer can be controlled to obtain high bonding properties.

[0058] FIG. 1 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 4 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 5 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 6 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 7 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 8 is a schematic cross-sectional view of a metal particle. FIG. 9 is a schematic cross-sectional view of a solder particle. FIG. 10 is a schematic plan view of a composite sheet. FIG. 11 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 12 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIG. 13 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. FIGS. 14(a) and 14(b) are schematic cross-sectional views showing an example of a method for manufacturing a composite sheet according to an embodiment. FIGS. 15(a), 15(b), and 15(c) are schematic cross-sectional views showing an example of a method for manufacturing a composite sheet according to an embodiment. FIGS. 16( a) and 16(b) are schematic cross-sectional views showing an example of a method for manufacturing a composite sheet according to an embodiment. FIGS. 17( a), 17(b), and 17(c) are schematic cross-sectional views showing an example of a method for manufacturing a composite sheet according to an embodiment. FIG. 18 is a schematic cross-sectional view showing an example of a method for manufacturing a composite sheet according to an embodiment. FIG. 19 is a schematic cross-sectional view showing an example of a method for manufacturing a composite sheet according to an embodiment. FIG. 20 is a schematic cross-sectional view showing an example of a method for manufacturing a composite sheet according to an embodiment. FIG. 21 is a schematic cross-sectional view showing an example of a bonded body according to an embodiment. FIG. 22 is a flowchart showing an example of a bonding method according to an embodiment. FIGS. 23( a), 23(b), and 23(c) are schematic cross-sectional views showing an example of a bonding method according to an embodiment. FIG. 24 is a schematic cross-sectional view showing a bonded state between a particle and a first and second bonded bodies. FIG. 25 is a flowchart showing an example of a bonding method according to an embodiment. FIG. 26 is a flowchart showing an example of a bonding method according to an embodiment. FIG. 27 is a flowchart showing an example of a bonding method according to an embodiment.FIG. 28 is a schematic cross-sectional view showing a bonded state between a particle and a first and second objects to be bonded. FIG. 29 is a flowchart showing an example of a bonding method according to an embodiment. FIG. 30 is a flowchart showing an example of a bonding method according to an embodiment. FIG. 31 is a flowchart showing an example of a bonding method according to an embodiment. FIG. 32 is a flowchart showing an example of a bonding method according to an embodiment. FIGS. 33( a) and 33(b) are schematic cross-sectional views showing a bonded state between a particle and a first and second objects to be bonded. FIG. 34 is a flowchart showing an example of a bonding method according to an embodiment. FIGS. 35( a) and 35(b) are schematic cross-sectional views showing a bonded state between a particle and a first and second objects to be bonded. FIGS. 36( a) and 36(b) are schematic cross-sectional views showing a bonded state between a particle and a first and second object to be bonded. FIGS. 37( a), 37(b), and 37(c) are schematic cross-sectional views showing an example of a bonding method according to an embodiment. FIG. 38 is a flowchart showing an example of a bonding method according to an embodiment. Fig. 39 is a schematic diagram showing a bonding apparatus used in the bonding method shown in Fig. 38. Figs. 40(a) and 40(b) are schematic diagrams showing a bonding apparatus used in the bonding method shown in Fig. 38.

[0059] Hereinafter, the present embodiment will be described in detail with reference to the drawings. In the following description, the same or corresponding parts will be denoted by the same reference numerals, and duplicated explanations will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0060] In this specification, the term "layer" encompasses not only a structure with a shape formed over the entire surface when observed in a plan view, but also a structure with a shape formed on a portion of the surface. Furthermore, in this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved. Furthermore, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0061] (Composite Sheet) FIGS. 1 to 7 are schematic cross-sectional views showing examples of a composite sheet according to an embodiment. As shown in FIGS. 1 to 7, a composite sheet 1 according to this embodiment includes a sheet layer 2 and particles 3 contained in the sheet layer 2. The composite sheet 1 is disposed, for example, between a first object to be joined 11 (see FIG. 21) and a second object to be joined 12 (see FIG. 21) and is used to join the first object to be joined 11 and the second object to be joined 12. The first object to be joined 11 and the second object to be joined 12 joined by the composite sheet 1 are referred to as a joined body 9 (see FIG. 21). The thickness of the composite sheet 1 (the thickness in the vertical direction in FIGS. 1 to 7) is, for example, 1 μm or more and 1 mm or less.

[0062] The sheet layer 2 is a layer formed in a sheet shape. Formed in a sheet shape means that the sheet shape is maintained. Note that the coating liquid used in conventional coating methods is not formed in a sheet shape because it cannot maintain its shape by itself. One of the two surfaces of the sheet layer 2 in the thickness direction D is referred to as a first surface 2a, and the other surface (the surface opposite to the first surface 2a) is referred to as a second surface 2b.

[0063] The sheet layer 2 may have at least one of thermal and electrical conductivity, or may not have such conductivity. Thermal conductivity is also referred to as thermal conductivity, thermal conductivity, etc. Electrical conductivity is also referred to as electrical conductivity, electrical conductivity, etc. Furthermore, the sheet layer 2 may have adhesiveness, or may not have adhesiveness.

[0064] The material of the sheet layer 2 is, for example, resin or carbon fiber, and the material of the sheet layer 2 having adhesiveness is, for example, silicone.

[0065] The sheet layer 2 may contain a flux component. The flux component contained in the sheet layer 2 is, for example, rosin acid.

[0066] The sheet layer 2 may contain a component that exhibits adhesive properties when subjected to at least one of pressure, heat, and ultrasonic waves. The component that exhibits adhesive properties when subjected to at least one of pressure, heat, and ultrasonic waves is, for example, acrylic.

[0067] The particles 3 are disposed between the first and second objects to be joined, separating the first and second objects to be joined by a predetermined distance. The particles 3 may have at least one of thermal and electrical conductivity, or may not have such conductivity. If the particles 3 have such conductivity, the particles 3 may have at least one of thermal and electrical conductivity greater than that of the sheet layer 2. In other words, the particles 3 may have at least one of thermal and electrical conductivity greater than that of the sheet layer 2. The material of the particles 3 is, for example, a metal such as copper, lead, or solder, or a ceramic such as boron nitride. The particles 3 may be composed of a single material or multiple materials. When the particles 3 are composed of multiple materials, the surface of the particles 3 may be composed of, for example, a metal such as copper, lead, or solder, or a ceramic such as boron nitride, and the interior of the particles 3 may be composed of a resin such as plastic.

[0068] Fig. 8 is a schematic cross-sectional view of a metal particle. As shown in Fig. 8, when at least the surface of particle 3 is metal, the surface of particle 3 is covered with an oxide film 31 formed by oxidation of the metal. In other words, an oxide film 31 formed by oxidation of the metal is present on the surface of particle 3. Fig. 9 is a schematic cross-sectional view of a solder particle. As shown in Fig. 9, when at least the surface of particle 3 is solder, the surface of particle 3 is covered with an oxide film 32 formed by oxidation of the solder. In other words, an oxide film 32 formed by oxidation of the solder is present on the surface of particle 3.

[0069] The shape of the particles 3 is not particularly limited. The particles 3 can have various shapes such as spheres, ellipsoids, cones, and cubes. The drawings show, as an example, a case where the particles 3 are spherical. The maximum length L of the particles 3 is, for example, 1 μm or more and 1 mm or less. The average particle size of the particles 3 is, for example, 0.5 μm or more and 1 mm or less. The average particle size of the particles 3 is determined by measuring the particle size of any 10 particles 3 (pcs) by observation using a scanning electron microscope (SEM) or an optical microscope, and averaging the obtained particle sizes.

[0070] 1 to 3, the particles 3 according to this embodiment are distributed only within a certain range in the thickness direction D of the sheet layer 2. In addition, as shown in FIGS. 4 to 7, other particles 3 according to this embodiment are arranged in a single layer that does not overlap in the thickness direction D of the sheet layer.

[0071] In the composite sheet 1 shown in Fig. 1, the particles 3 are distributed only within a certain range in the thickness direction D at the end of the sheet layer 2 on the first surface 2a side in the thickness direction D. In the composite sheet 1 shown in Fig. 2, the particles 3 are distributed only within a certain range in the thickness direction D at the end of the sheet layer 2 on the second surface 2b side in the thickness direction D. In the composite sheet 1 shown in Fig. 3, the particles 3 are distributed only within a certain range in the thickness direction D at the center of the sheet layer 2 in the thickness direction D.

[0072] When the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, the particles 3 may be arranged in multiple layers overlapping in the thickness direction D, or may be arranged in a single layer that does not overlap in the thickness direction D. Figures 1 to 3 show, as an example, a case where the particles 3 are arranged in multiple layers overlapping in the thickness direction D.

[0073] Furthermore, when the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, the particles 3 may or may not be exposed from the sheet layer 2. Figures 1 to 3 show, as an example, a case where the particles 3 are not exposed from the sheet layer 2, that is, a case where the particles 3 are entirely embedded in the sheet layer 2.

[0074] The maximum length L of the particle 3 may be half or more of the thickness T2 of the sheet layer 2.

[0075] 4, the maximum length L of the particles 3 is smaller than the thickness T2 of the sheet layer 2. The particles 3 are not exposed from the sheet layer 2, but are entirely embedded within the sheet layer 2.

[0076] 5, the maximum length L of the particles 3 is the same as the thickness T2 of the sheet layer 2. The particles 3 are exposed from both the first surface 2a and the second surface 2b of the sheet layer 2.

[0077] 6, the maximum length L of the particles 3 is greater than the thickness T2 of the sheet layer 2. The particles 3 are exposed from both the first surface 2a and the second surface 2b of the sheet layer 2.

[0078] 7 , the particles 3 are exposed from the first surface 2a of the sheet layer 2, but not from the second surface 2b of the sheet layer 2. In other words, the particles 3 are embedded in the sheet layer 2 from the second surface 2b. In this case, the maximum length L of the particles 3 may be the same as, smaller than, or larger than the thickness T2 of the sheet layer 2.

[0079] When the particles 3 are arranged in a single layer that does not overlap in the thickness direction D of the sheet layer, the particles 3 may be arranged regularly or irregularly. Fig. 10 is a schematic plan view of a composite sheet showing a case in which the particles 3 are arranged regularly. For example, when the first object to be joined 11 and the second object to be joined 12 have parts to be joined 11a and parts to be joined 12a (see Fig. 21) that are connected to the particles 3, and these parts to be joined 11a and parts to be joined 12a are arranged regularly, the particles 3 may be arranged regularly so as to correspond to the parts to be joined 11a of the first object to be joined 11 and the parts to be joined 12a of the second object to be joined 12.

[0080] The ratio of the projected area of ​​the particles 3 per unit area of ​​the composite sheet 1 as viewed from the thickness direction D of the sheet layer 2 is, for example, more than 15%, preferably 40% or more, and more preferably 75% or more. The viewing direction as viewed from the thickness direction D is the direction perpendicular to the paper surface of FIG.

[0081] 11 and 12 are schematic cross-sectional views illustrating examples of composite sheets according to embodiments. As shown in FIGS. 11 and 12 , the composite sheet 1 may include a second sheet 4 laminated on a sheet layer 2 containing particles 3. In this case, the second sheet 4 may be laminated on at least one of the two surfaces of the sheet layer 2. That is, the second sheet 4 may be laminated on the first surface 2a of the sheet layer 2, on the second surface 2b of the sheet layer 2, or on both the first surface 2a and the second surface 2b of the sheet layer 2. FIG. 11 illustrates, as an example, a case in which the second sheet 4 is laminated on the first surface 2a of the sheet layer 2. The sheet layer 2 may also be laminated on at least one of the two surfaces of the second sheet 4. FIG. 12 illustrates, as an example, a case in which the sheet layer 2 is laminated on both surfaces of the second sheet 4. The second sheet 4 may be, for example, a release sheet that can be easily peeled from the sheet layer 2, or a substrate sheet that imparts rigidity to the composite sheet 1.

[0082] 13 is a schematic cross-sectional view showing an example of a composite sheet according to an embodiment. As shown in FIG. 13, the composite sheet 1 may include a third sheet 5 having, as an inner layer, a sheet layer 2 containing particles 3. In other words, the sheet layer 2 may be disposed inside the third sheet 5, and the first surface 2 a and the second surface 2 b of the sheet layer 2 may be covered by the third sheet 5.

[0083] The composite sheet 1 may also be formed by laminating a plurality of sheet layers 2 containing particles 3 .

[0084] (Manufacturing Method of Composite Sheet) Next, a manufacturing method of the composite sheet according to this embodiment will be described. The manufacturing method of the composite sheet according to this embodiment is a method for manufacturing the composite sheet 1 described above.

[0085] In the method for producing a composite sheet according to this embodiment, particles 3 are placed on the surface of a sheet layer 2 formed into a sheet shape, and pressure is applied in the thickness direction D of the sheet layer 2 to embed the particles 3 into the sheet layer 2. As described above, being formed into a sheet shape means that the shape of the sheet is maintained. Note that coating liquids used in conventional coating methods are not formed into a sheet shape because they cannot maintain their shape by themselves.

[0086] In the method for producing a composite sheet according to this embodiment, the maximum length L of the particle 3 may be set to half or more of the thickness T2 of the sheet layer 2.

[0087] 14(a) and 14(b) are schematic cross-sectional views illustrating an example of a method for manufacturing a composite sheet according to an embodiment. In the method for manufacturing a composite sheet shown in FIGS. 14(a) and 14(b), particles 3 are first disposed on the surface of a sheet layer 2 formed into a sheet shape. The particles 3 may be disposed in a single layer or multiple layers. Next, pressure is applied in the thickness direction of the sheet layer 2 to embed the particles 3 disposed on the surface of the sheet layer 2 into the sheet layer 2. The particles 3 are distributed only within a certain range in the thickness direction D at the end of the sheet layer 2 on the first surface 2a side or the second surface 2b side in the thickness direction D. This allows the composite sheet 1 shown in FIG. 1 or 2 to be manufactured.

[0088] 15( a), 15(b), and 15(c) are schematic cross-sectional views illustrating an example of a method for manufacturing a composite sheet according to an embodiment. In the method for manufacturing a composite sheet shown in FIGS. 15(a), 15(b), and 15(c), particles 3 are first disposed on the surface of a first sheet layer 21 formed into a sheet and constituting a part of the sheet layer 2. The particles 3 may be disposed in a single layer or multiple layers on the surface of the first sheet layer 21. Next, a second sheet layer 22 formed into a sheet and constituting a part of the sheet layer 2 is disposed on the surface of the first sheet layer 21 on which the particles 3 are disposed. This results in the particles 3 being sandwiched between the first sheet layer 21 and the second sheet layer 22. Next, pressure is applied in opposing directions between the first sheet layer 21 and the second sheet layer 22 to embed the particles 3 in at least one of the first sheet layer 21 and the second sheet layer 22. At this time, the particles 3 are distributed only within a certain range in the thickness direction D at the center of the sheet layer 2 in the thickness direction D. In this way, the composite sheet 1 shown in FIG. 3 can be produced.

[0089] 16(a) and 16(b) are schematic cross-sectional views illustrating an example of a method for manufacturing a composite sheet according to an embodiment. In the method for manufacturing a composite sheet shown in FIGS. 16(a) and 16(b), particles 3 are first arranged on the surface of a sheet layer 2 formed into a sheet shape. The particles 3 are then arranged in a single layer in the thickness direction of the sheet layer 2. The particles 3 may be arranged regularly or irregularly. For example, a method for arranging the particles 3 regularly includes a method for arranging the particles 3 using a metal mask. Next, pressure is applied in the thickness direction of the sheet layer 2 to embed the particles 3 arranged on the surface of the sheet layer 2 into the sheet layer 2. This allows the composite sheet 1 shown in FIGS. 4 to 7 to be manufactured.

[0090] Here, by making the maximum length of the particles 3 smaller than the thickness of the sheet layer 2, it is possible to produce the composite sheet shown in Figure 4 in which the particles 3 are not exposed from the sheet layer 2 but are entirely embedded within the sheet layer 2, or the composite sheet 1 shown in Figure 7 in which the particles 3 are exposed from either the first surface 2a or the second surface 2b of the sheet layer 2.

[0091] Furthermore, by making the maximum length of the particles 3 the same as the thickness of the sheet layer 2, it is possible to produce the composite sheet 1 shown in FIG. 5 in which the particles 3 are exposed from both the first surface 2 a and the second surface 2 b of the sheet layer 2, or the composite sheet 1 shown in FIG. 7 in which the particles 3 are exposed from either the first surface 2 a or the second surface 2 b of the sheet layer 2.

[0092] Furthermore, by making the maximum length of the particles 3 greater than the thickness of the sheet layer 2, it is possible to produce the composite sheet 1 shown in Figure 6, in which the particles 3 are exposed from both the first surface 2a and the second surface 2b of the sheet layer 2.

[0093] 17(a), 17(b), and 17(c) are schematic cross-sectional views illustrating an example of a method for manufacturing a composite sheet according to an embodiment. In the composite sheet manufacturing method illustrated in FIGS. 17(a), 17(b), and 17(c), particles 3 are first disposed on the surface of a first sheet layer 21 formed into a sheet and constituting a part of the sheet layer 2. The particles 3 are then disposed in a single layer in the thickness direction of the sheet layer 2. The particles 3 may be arranged regularly or irregularly. Next, a second sheet layer 22 formed into a sheet and constituting a part of the sheet layer 2 is disposed on the surface of the first sheet layer 21 on which the particles 3 are disposed. This results in the particles 3 being sandwiched between the first sheet layer 21 and the second sheet layer 22. Next, pressure is applied in opposing directions between the first sheet layer 21 and the second sheet layer 22, embedding the particles 3 in at least one of the first sheet layer 21 and the second sheet layer 22. This allows the composite sheet 1 illustrated in FIG. 4 to be manufactured, in which the particles 3 are not exposed from the sheet layer 2.

[0094] FIG. 18 is a schematic cross-sectional view illustrating an example of a manufacturing method for a composite sheet according to an embodiment. In the manufacturing method for a composite sheet illustrated in FIG. 18 , first, a first sheet layer 21 formed into a sheet shape and constituting a part of the sheet layer 2, and a second sheet layer 22 formed into a sheet shape and constituting a part of the sheet layer 2, are prepared. A substrate layer 23 is laminated on one side of the first sheet layer 21. A substrate layer 24 is laminated on one side of the second sheet layer 22. Next, while conveying the first sheet layer 21, particles 3 are arranged on the surface of the first sheet layer 21 opposite the substrate layer 23. At this time, the particles 3 are arranged in a single layer in the thickness direction of the sheet layer 2. The particles 3 may be arranged regularly or irregularly. Next, the second sheet layer 22 is conveyed onto the surface of the first sheet layer 21 on which the particles 3 are arranged. At this time, the second sheet layer 22 is conveyed so that the surface of the second sheet layer 22 opposite the substrate layer 24 faces the first sheet layer 21. As a result, the particles 3 are sandwiched between the first sheet layer 21 and the second sheet layer 22. Next, the first sheet layer 21 and the second sheet layer 22 are sandwiched between a pair of rollers 6, 6, and the particles 3 are embedded in the first sheet layer 21 and the second sheet layer 22. At this time, the first sheet layer 21 and the second sheet layer 22 are sandwiched between the pair of rollers 6, 6 so that the first sheet layer 21 is extruded from between the base layer 23 and the particles 3, and the second sheet layer 22 is extruded from between the base layer 24 and the particles 3. As a result, the composite sheet 1 shown in FIG. 5 can be produced, in which the maximum length L of the particles 3 is the same as the thickness T2 of the sheet layer 2 and the particles 3 are exposed from both the first surface 2 a and the second surface 2 b of the sheet layer 2.

[0095] FIG. 19 is a schematic cross-sectional view illustrating an example of a manufacturing method for a composite sheet according to an embodiment. In the manufacturing method for a composite sheet illustrated in FIG. 19 , first, a first sheet layer 21 formed into a sheet shape and constituting a part of the sheet layer 2, and a second sheet layer 22 formed into a sheet shape and constituting a part of the sheet layer 2, are prepared. A release layer 25 and a base layer 23 are laminated in this order on one side of the first sheet layer 21. Furthermore, a release layer 26 and a base layer 24 are laminated in this order on one side of the second sheet layer 22. Next, while conveying the first sheet layer 21, particles 3 are arranged on the surface of the first sheet layer 21 opposite the base layer 23. At this time, the particles 3 are arranged in a single layer in the thickness direction of the sheet layer 2. The particles 3 may be arranged regularly or irregularly. Next, the second sheet layer 22 is conveyed onto the surface of the first sheet layer 21 on which the particles 3 are arranged. At this time, the second sheet layer 22 is conveyed so that the surface of the second sheet layer 22 opposite the base layer 24 faces the first sheet layer 21. As a result, the particles 3 are sandwiched between the first sheet layer 21 and the second sheet layer 22. Next, the first sheet layer 21 and the second sheet layer 22 are sandwiched between a pair of rollers 6, 6, and the particles 3 are embedded in the first sheet layer 21 and the second sheet layer 22. At this time, the first sheet layer 21 and the second sheet layer 22 are sandwiched between the pair of rollers 6, 6 so that the first sheet layer 21 and the release layer 25 are extruded from between the base layer 23 and the particles 3, and the second sheet layer 22 and the release layer 26 are extruded from between the base layer 24 and the particles 3. Next, the release layer 25 is peeled from the first sheet layer 21, and the release layer 26 is peeled from the second sheet layer 22. As a result, the composite sheet 1 shown in FIG. 6 can be produced, in which the maximum length L of the particles 3 is greater than the thickness T2 of the sheet layer 2 and the particles 3 are exposed from both the first surface 2a and the second surface 2b of the sheet layer 2.

[0096] FIG. 20 is a schematic cross-sectional view illustrating an example of a manufacturing method for a composite sheet according to an embodiment. In the manufacturing method for a composite sheet illustrated in FIG. 20 , first, a first sheet layer 21 formed into a sheet shape and constituting a part of the sheet layer 2, and a second sheet layer 22 formed into a sheet shape and constituting a part of the sheet layer 2, are prepared. A substrate layer 23 is laminated on one side of the first sheet layer 21. A substrate layer 24 is laminated on one side of the second sheet layer 22. Next, while conveying the first sheet layer 21, particles 3 are arranged on the surface of the first sheet layer 21 opposite the substrate layer 23. At this time, the particles 3 are arranged in a single layer in the thickness direction of the sheet layer 2. The particles 3 may be arranged regularly or irregularly. Next, the second sheet layer 22 is conveyed onto the surface of the first sheet layer 21 on which the particles 3 are arranged. At this time, the second sheet layer 22 is conveyed so that the surface of the second sheet layer 22 opposite the substrate layer 24 faces the first sheet layer 21. As a result, the particles 3 are sandwiched between the first sheet layer 21 and the second sheet layer 22. Next, the first sheet layer 21 and the second sheet layer 22 are sandwiched between a pair of elastic rollers 7, 7, and the particles 3 are embedded in the first sheet layer 21 and the second sheet layer 22. At this time, the first sheet layer 21 and the second sheet layer 22 are sandwiched between the pair of elastic rollers 7, 7 so that the first sheet layer 21 is extruded from between the base layer 23 and the particles 3, the second sheet layer 22 is extruded from between the base layer 24 and the particles 3, and further, a portion of the first sheet layer 21 is extruded between adjacent particles 3, and a portion of the second sheet layer 22 is extruded between adjacent particles 3. As a result, the composite sheet 1 shown in FIG. 6 can be produced, in which the maximum length L of the particles 3 is greater than the thickness T2 of the sheet layer 2 and the particles 3 are exposed from both the first surface 2a and the second surface 2b of the sheet layer 2.

[0097] In these methods for manufacturing composite sheets, the thermal or electrical conductivity of the particles 3 may be greater than the thermal or electrical conductivity of the sheet layer 2, and the ratio of the projected area of ​​the particles 3 per unit area of ​​the composite sheet 1 as viewed in the thickness direction D of the sheet layer 2 may be, for example, greater than 15%, preferably 40% or more, and more preferably 75% or more.

[0098] The material of the particles 3 may be, for example, a metal such as copper, lead, or solder, or a ceramic such as boron nitride. The particles 3 may be made of a single material or a plurality of materials. When the particles 3 are made of a plurality of materials, the surfaces of the particles 3 may be made of, for example, a metal such as copper, lead, or solder, or a ceramic such as boron nitride.

[0099] The sheet layer 2 may also contain a flux component. The sheet layer 2 may also contain a component that exhibits adhesive properties when subjected to at least one of pressure, heat, and ultrasonic waves.

[0100] (Jointed Body) Next, the joined body according to this embodiment will be described.

[0101] 21 is a schematic cross-sectional view showing an example of a bonded body according to an embodiment. As shown in FIG. 21, a bonded body 9 according to this embodiment is formed by bonding a first object to be bonded 11 and a second object to be bonded 12 with the composite sheet 1 described above.

[0102] The first bonded body 11 and the second bonded body 12 are not particularly limited, and may be, for example, a chip and a substrate used in a semiconductor package, or a substrate and a heat sink used in an IGBT (Insulated Gate Bipolar Transistor) power module.

[0103] The first object to be joined 11 and the second object to be joined 12 may have a part to be joined 11 a and a part to be joined 12 a to be joined to the particle 3. The parts to be joined 11 a and the parts to be joined 12 a may be arranged regularly or irregularly. The parts to be joined 11 a and the parts to be joined 12 a may be made of metal.

[0104] (Bonding Method) Next, a bonding method according to this embodiment will be described. In the bonding method according to this embodiment, the composite sheet 1 described above is placed between a first object to be bonded and a second object to be bonded, and the first object to be bonded and the second object to be bonded are bonded via the composite sheet 1. The first object to be bonded and the second object to be bonded are not particularly limited, and may be, for example, a chip and a substrate used in a semiconductor package, or a substrate and a heat sink used in an IGBT power module.

[0105] Fig. 22 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 22 uses a composite sheet 1 having particles 3, at least the surfaces of which are solder, contained in a sheet layer 2, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 22 includes a placement step S11, a pressure step S12, an ultrasonic wave application step S13, and a heating step S14.

[0106] In the arrangement step S11, as shown in Fig. 23(a), the composite sheet 1 is arranged between the first object to be joined 11 and the second object to be joined 12. Fig. 23(a) is a schematic cross-sectional view showing an example of the joining method according to the embodiment. At this time, the particles 3 are arranged so that the positions of the particles 3 correspond to the positions of the parts to be joined 11a of the first object to be joined 11 and the parts to be joined 12a of the second object to be joined 12.

[0107] The pressurizing step S12 is performed after the placing step S11. In the pressurizing step S12, as shown in Fig. 23(b), the first object to be bonded 11 and the second object to be bonded 12 are pressed in the opposing direction of the first object to be bonded 11 and the second object to be bonded 12, thereby bringing the particles 3 into contact with the part to be bonded 11a of the first object to be bonded 11 and the part to be bonded 12a of the second object to be bonded 12. Fig. 23(b) is a schematic cross-sectional view showing an example of the bonding method according to the embodiment.

[0108] The ultrasonic wave application step S13 is performed simultaneously with or after the pressure application step S12. In the ultrasonic wave application step S13, as shown in Figures 23(c) and 24, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby removing oxide films present on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a, and the surfaces of the portions to be bonded 12a. Figure 23(c) is a schematic cross-sectional view showing an example of a bonding method according to an embodiment. Figure 24 is a schematic cross-sectional view showing the bonded state between the particles and the first object to be bonded and the second object to be bonded.

[0109] The heating step S14 is performed after the ultrasonic wave application step S13. In the heating step S14, the composite sheet 1, the first object to be joined 11, and the second object to be joined 12 are heated by, for example, placing the composite sheet 1, the first object to be joined 11, and the second object to be joined 12 in a high-temperature environment. This produces a joined body 9 in which the first object to be joined 11 and the second object to be joined 12 are joined via the composite sheet 1.

[0110] Fig. 25 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 25 uses a composite sheet 1 having particles 3, at least the surface of which is solder, contained in a sheet layer 2, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 25 includes a placement step S11, a pressure step S12, and an ultrasonic application step S23. The placement step S11 and the pressure step S12 are the same as those of the bonding method shown in Fig. 22.

[0111] The ultrasonic wave application step S23 is performed simultaneously with or after the pressure application step S12. In the ultrasonic wave application step S23, as shown in FIGS. 23(c) and 24, ultrasonic waves are applied to at least one of the first object to be joined 11 and the second object to be joined 12, thereby melting the solder of the particles 3 by frictional heat and bonding the particles 3 to the bonded portions 11a of the first object to be joined 11 and the bonded portions 12a of the second object to be joined 12. This produces a bonded body 9 in which the first object to be joined 11 and the second object to be joined 12 are bonded via the composite sheet 1. Note that after bonding the particles 3 to the bonded portions 11a of the first object to be joined 11 and the bonded portions 12a of the second object to be joined 12 in the ultrasonic wave application step S23, a step similar to the heating step S14 of the bonding method shown in FIG. 22 may be performed.

[0112] Fig. 26 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 26 uses a composite sheet 1 having particles 3, at least the surface of which is metal, contained in a sheet layer 2, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 26 includes a placement step S11, a pressure step S12, and an ultrasonic application step S33. The placement step S11 and the pressure step S12 are similar to the bonding method shown in Fig. 22.

[0113] The ultrasonic wave application step S33 is performed simultaneously with or after the pressurization step S12. In the ultrasonic wave application step S33, as shown in FIGS. 23( c) and 24, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby forming clean surfaces on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a of the first object to be bonded 11, and the surfaces of the portions to be bonded 12a of the second object to be bonded 12, and solid-state bonding is performed between the particles 3 and the portions to be bonded 11a of the first object to be bonded 11 and the portions to be bonded 12a of the second object to be bonded 12. This produces a bonded body 9 in which the first object to be bonded 11 and the second object to be bonded 12 are bonded via the composite sheet 1. Note that after the particles 3 and the portions to be bonded 11a of the first object to be bonded 11 and the portions to be bonded 12a of the second object to be bonded 12 are solid-state bonded in the ultrasonic wave application step S33, a step similar to the heating step S14 of the bonding method shown in FIG. 22 may be performed.

[0114] Fig. 27 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 27 uses a composite sheet 1 having particles 3, at least the surface of which is metal, contained in a sheet layer 2, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 27 includes a placement step S11, a pressure step S12, and an ultrasonic application step S43. The placement step S11 and the pressure step S12 are the same as those of the bonding method shown in Fig. 22.

[0115] The ultrasonic wave application step S43 is performed simultaneously with or after the pressure application step S12. In the ultrasonic wave application step S43, as shown in FIGS. 23(c) and 28, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby smoothing the bonding surfaces between the particle 3 and the bonded portion 11a of the first object to be bonded 11 and the bonded portion 12a of the second object to be bonded 12. FIG. 28 is a schematic cross-sectional view showing the bonded state between the particle 3 and the first object to be bonded and the second object to be bonded. Thereafter, for example, a heating step or the like is performed as necessary to produce a bonded body 9 in which the first object to be bonded 11 and the second object to be bonded 12 are bonded via the composite sheet 1.

[0116] Fig. 29 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 29 uses a composite sheet 1 having particles 3, at least the surface of which is metal, contained in a sheet layer 2, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 29 includes a placement step S11, a pressure step S12, and an ultrasonic application step S53. The placement step S11 and the pressure step S12 are similar to the bonding method shown in Fig. 22.

[0117] The ultrasonic wave application step S53 is performed simultaneously with or after the pressurization step S12. In the ultrasonic wave application step S53, as shown in Figures 23(c) and 24, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby removing oxide films present on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a, and the surfaces of the portions to be bonded 12a, and forming clean surfaces on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a of the first object to be bonded 11, and the surfaces of the portions to be bonded 12a of the second object to be bonded 12, thereby solid-state bonding the particles 3 to the portions to be bonded 11a of the first object to be bonded 11 and the portions to be bonded 12a of the second object to be bonded 12. This produces a bonded body 9 in which the first object to be bonded 11 and the second object to be bonded 12 are bonded via the composite sheet 1. In addition, in the ultrasonic application step S53, after the particles 3, the joining portion 11 a of the first joined body 11, and the joining portion 12 a of the second joined body 12 are solid-state joined, a step similar to the heating step S14 of the joining method shown in FIG. 22 may be performed.

[0118] Fig. 30 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 30 uses a composite sheet 1 having particles 3, at least the surface of which is metal, contained in a sheet layer 2 containing a flux component, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 30 includes a placement step S11, a pressure application step S62, and a heating step S14. The placement step S11 and the heating step S14 are similar to those of the bonding method shown in Fig. 22.

[0119] The pressurizing step S62 is performed after the arrangement step S11. In the pressurizing step S62, as shown in Figures 23(b) and 24, the first and second objects to be joined 11 and 12 are pressed in the opposing direction of the first and second objects to be joined 11 and 12, thereby bringing the particles 3 into contact with the joined portions 11a of the first and second objects to be joined 11 and 12a of the second objects to be joined 12, and removing oxide films present on the surfaces of the particles 3, the surfaces of the joined portions 11a, and the surfaces of the joined portions 12a by the flux component contained in the sheet layer 2. Thereafter, the heating step S14 is performed to produce a joined body 9 in which the first and second objects to be joined 11 and 12 are joined via the composite sheet 1.

[0120] Fig. 31 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 31 uses a composite sheet 1 having particles 3, at least the surface of which is metal, contained in a sheet layer 2 containing a flux component, a first object to be bonded 11 having a metal portion to be bonded 11a, and a second object to be bonded 12 having a metal portion to be bonded 12a. The bonding method shown in Fig. 31 includes a placement step S11, a pressure step S72, and an ultrasonic application step S73. The placement step S11 is the same as the bonding method shown in Fig. 22.

[0121] 23(b) and 24 , in the pressurizing step S72, the first object to be joined 11 and the second object to be joined 12 are pressed in the opposing direction of the first object to be joined 11 and the second object to be joined 12, thereby bringing the particles 3 into contact with the parts to be joined 11 a of the first object to be joined 11 and the parts to be joined 12 a of the second object to be joined 12, and removing oxide films present on the surfaces of the particles 3, the parts to be joined 11 a, and the parts to be joined 12 a by the flux component contained in the sheet layer 2.

[0122] The ultrasonic wave application step S73 is performed simultaneously with or after the pressurization step S72. In the ultrasonic wave application step S73, as shown in Figures 23(c) and 24, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby removing oxide films present on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a, and the surfaces of the portions to be bonded 12a, and forming clean surfaces on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a of the first object to be bonded 11, and the surfaces of the portions to be bonded 12a of the second object to be bonded 12, thereby solid-state bonding the particles 3 to the portions to be bonded 11a of the first object to be bonded 11 and the portions to be bonded 12a of the second object to be bonded 12. This produces a bonded body 9 in which the first object to be bonded 11 and the second object to be bonded 12 are bonded via the composite sheet 1. In addition, in the ultrasonic application step S73, after the particles 3 and the joining portion 11 a of the first joined body 11 and the joining portion 12 a of the second joined body 12 are solid-state joined, a step similar to the heating step S14 of the joining method shown in FIG. 22 may be performed.

[0123] FIG. 32 is a flowchart illustrating an example of a bonding method according to an embodiment. FIGS. 33(a) and 33(b) are schematic cross-sectional views illustrating the bonded state between particles and first and second objects to be bonded. The bonding method illustrated in FIG. 32 uses a first object to be bonded 11 having a portion to be bonded 11a with a recess 11c formed therein and a second object to be bonded 12 having a portion to be bonded 12a with a recess 12c formed therein, as illustrated in FIG. 33. Furthermore, the particle 3 is positioned at a position corresponding to the recess 11c of the portion to be bonded 11a and the recess 12c of the portion to be bonded 12a, and is larger than the recess 11c of the portion to be bonded 11a and the recess 12c of the portion to be bonded 12a. The bonding method illustrated in FIG. 32 includes a placement step S81 and a pressure application step S82.

[0124] 33(a), the composite sheet 1 is placed between the first object to be joined 11 and the second object to be joined 12. At this time, the particles 3 are placed so that the positions of the particles 3 correspond to the positions of the recesses 11c of the object to be joined 11a and the recesses 12c of the object to be joined 12a.

[0125] The pressurizing step S82 is performed after the placing step S81. In the pressurizing step S82, as shown in FIG. 33( b), the first and second objects to be joined 11 and 12 are pressed in the opposing direction of the first and second objects to be joined 11 and 12, forcing the particles 3 into the recesses 11c of the joined portions 11a and 12c of the joined portions 12a, thereby bonding the particles 3 to the recesses 11c of the joined portions 11a and 12c of the joined portions 12a. This produces a bonded body 9 in which the first and second objects to be joined 11 and 12 are bonded via the composite sheet 1. Note that, after bonding the particles 3 to the recesses 11c of the joined portions 11a and 12c of the joined portions 12a in the pressurizing step S82, a step similar to the heating step S14 of the bonding method shown in FIG. 22 may be performed.

[0126] FIG. 34 is a flowchart illustrating an example of a bonding method according to an embodiment. FIGS. 35(a), 35(b), 36(a), and 36(b) are schematic cross-sectional views illustrating the bonding state between particles and first and second bonded bodies. The bonding method illustrated in FIG. 34 uses a composite sheet 1 having particles 3, at least the surfaces of which are metal, contained in a sheet layer 2, a first bonded body 11 having a bonded portion 11a with a metal recess 11c formed on its surface, and a second bonded body 12 having a bonded portion 12a with a metal recess 12c formed on its surface, as shown in FIGS. 35(a), 35(b), and 36(a). The particles 3 are positioned corresponding to the recess 11c of the bonded portion 11a and the recess 12c of the bonded portion 12a, and are smaller than the recess 11c of the bonded portion 11a and the recess 12c of the bonded portion 12a. The thermal expansion coefficient of the particles 3 is greater than the linear expansion coefficients of the bonded portions 11a and 12a. The joining method shown in FIG. 34 includes a placement step S91 and a pressurizing and heating step S92.

[0127] 35(a), the composite sheet 1 is placed between the first object to be joined 11 and the second object to be joined 12. At this time, the particles 3 are placed so that the positions of the particles 3 correspond to the positions of the recesses 11c of the object to be joined 11a and the recesses 12c of the object to be joined 12a.

[0128] The pressurizing and heating step S92 is performed after the placement step S91. In the pressurizing and heating step S92, as shown in FIG. 35(b), particles 3 are inserted into the recesses 11c of the bonded portions 11a and the recesses 12c of the bonded portions 12a. Next, as shown in FIGS. 35(b) and 36(a), the first and second bonded objects 11 and 12 are heated while being pressurized in the opposing direction of the first and second bonded objects 11 and 12, thereby diffusion bonding the particles 3 to the recesses 11c of the bonded portions 11a and the recesses 12c of the bonded portions 12a. Note that, as shown in FIG. 36(b), the first and second bonded objects 11 and 12 may be further shifted relative to each other to deform the particles 3, thereby mechanically bonding the particles 3 to the recesses 11c of the bonded portions 11a and the recesses 12c of the bonded portions 12a. This produces a bonded body 9 in which the first and second objects to be bonded 11 and 12 are bonded via the composite sheet 1. After the particles 3 are diffusion-bonded to the recesses 11c of the portions to be bonded 11a and the recesses 12c of the portions to be bonded 12a in the pressurizing and heating step S92, a step similar to the heating step S14 of the bonding method shown in FIG.

[0129] 37(a), 37(b), and 37(c) are schematic cross-sectional views showing an example of a bonding method according to an embodiment, where FIG. 37(a) shows a second bonded body, FIG. 37(b) shows a composite sheet, and FIG. 37(c) shows a first bonded body. As shown in FIG. 37(a), 37(b), and 37(c), in each of the above-described bonding methods, a flux component may be applied to at least one surface of the composite sheet 1, the first bonded body 11, and the second bonded body 12 before pressing the first bonded body 11 and the second bonded body 12 together. That is, the flux component F may be applied to at least one surface of the composite sheet 1, the surface of the first bonded body 11 facing the composite sheet 1, or the surface of the second bonded body 12 facing the composite sheet 1.

[0130] When applying ultrasonic waves in each of the above-described bonding methods, the ultrasonic waves may be applied to at least one of the first body to be bonded 11 and the second body to be bonded 12 in a reducing environment. The reducing environment may be, for example, a hydrogen atmosphere.

[0131] Fig. 38 is a flowchart showing an example of a bonding method according to an embodiment. The bonding method shown in Fig. 38 includes an inspection step S101 and a bonding step S102. The bonding step S102 is one of the bonding methods described above. In the bonding method shown in Fig. 38, a tape-like composite sheet 1 wound on a reel (not shown) may be used, or a composite sheet 1 formed in a sheet form may be used. Then, the inspection step S101 and the bonding step S102 may be performed while transporting such a composite sheet 1.

[0132] The inspection step S101 is performed before the bonding step S102. That is, in the bonding method shown in FIG. 38 , the inspection step S101 is performed before each of the above-described bonding methods (bonding step S102). In the inspection step S101, the composite sheet 1 is inspected. The inspection of the composite sheet 1 can be performed, for example, by visual inspection of the composite sheet 1. For example, when the first object to be bonded 11 has portions to be bonded 11a arranged in specific positions, the second object to be bonded 12 has portions to be bonded 12a arranged in specific positions, and the particles 3 are arranged in positions corresponding to the portions to be bonded 11a and 12a, the composite sheet 1 is inspected by visual inspection to determine whether the particles 3 are present in the predetermined positions of the composite sheet 1.

[0133] The bonding step S102 is performed after the inspection step S101. In the bonding step S102, the first and second objects to be bonded 11 and 12 are not bonded together by a composite sheet 1 determined to be defective in the inspection step S101, but the first and second objects to be bonded 11 and 12 are bonded together by a composite sheet 1 determined to be non-defective in the inspection step S101.

[0134] 39, 40(a), and 40(b) are schematic diagrams showing a bonding apparatus used in the bonding method shown in FIG. 38. As shown in FIG. 39, the bonding apparatus 100 used in the bonding method shown in FIG. 38 includes an appearance inspection device 101 that performs an appearance inspection of the composite sheet 1 and an arm 102 that holds a first bonded object 11. The appearance inspection device 101 performs an appearance inspection of the conveyed composite sheet 1. The arm 102 skips composite sheets 1 determined to be defective by the appearance inspection device 101 and presses the first bonded object 11 against composite sheets 1 determined to be non-defective by the appearance inspection device 101. Then, as shown in FIGS. 39 and 40(a), the arm 102 picks up the first bonded object 11 to which the composite sheet 1 has been attached, and presses the composite sheet 1 to which the first bonded object 11 has been attached against a second bonded object 12, as shown in FIG. 40(b). Thereafter, similar to the above-mentioned respective joining methods, a pressure application process, an ultrasonic application process, a heating process, etc. are carried out to produce a joined body 9 in which the first joined body 11 and the second joined body 12 are joined via the composite sheet 1.

[0135] As described above, in the method for producing a composite sheet according to this embodiment, particles 3 are disposed on the surface of a sheet layer 2 formed into a sheet shape, and pressure is applied in the thickness direction D of the sheet layer 2 to embed the particles 3 into the sheet layer 2. Therefore, the position of the particles 3 in the sheet layer 2 can be more controlled than in a method for producing a composite sheet by dispersing particles in a coating liquid. For example, it is possible to produce a composite sheet 1 in which the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, or a composite sheet 1 in which the particles 3 are arranged in a single layer that does not overlap in the thickness direction of the sheet layer 2. In this way, by using the produced composite sheet 1 to join a first object to be joined 11 and a second object to be joined 12, high joining characteristics can be obtained.

[0136] In addition, in the composite sheet manufacturing method according to this embodiment, particles 3 are disposed on the surface of a first sheet layer 21 formed into a sheet shape, a second sheet layer 22 formed into a sheet shape is disposed on the surface of the first sheet layer 21 on which the particles 3 are disposed, and pressure is applied to the first sheet layer 21 and the second sheet layer 22 in the opposing direction of the first sheet layer 21 and the second sheet layer 22 to embed the particles 3 in at least one of the first sheet layer 21 and the second sheet layer 22. In this case, the position of the particles 3 in the sheet layer 2 can be more controlled than in a method of manufacturing a composite sheet by dispersing particles in a coating liquid. For example, it is possible to manufacture a composite sheet 1 in which the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, or a composite sheet 1 in which the particles 3 are disposed in a single layer that does not overlap in the thickness direction D of the sheet layer 2. In this way, the manufactured composite sheet 1 can be used to bond a first object to be bonded 11 and a second object to be bonded 12, thereby achieving high bonding properties.

[0137] Furthermore, in the method for producing a composite sheet according to this embodiment, when the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, the produced composite sheet 1 is used to bond the first object to be joined 11 and the second object to be joined 12, thereby making it easier to control the distance between the first object to be joined 11 and the second object to be joined 12. This makes it possible, for example, to maintain the distance between the first object to be joined 11 and the second object to be joined 12 at a thickness in the range in which the particles 3 are distributed in the thickness direction D of the sheet layer 2.

[0138] Furthermore, in the method for manufacturing a composite sheet according to the present embodiment, if the maximum length L of the particles 3 is set to be half or more of the thickness of the sheet layer 2, when the manufactured composite sheet 1 is used to join the first object to be joined 11 and the second object to be joined 12, the particles 3 can be easily brought into contact with the first object to be joined 11 and the second object to be joined 12.

[0139] Furthermore, in an example of the composite sheet manufacturing method according to the present embodiment, when the particles 3 are arranged in a single layer that does not overlap in the thickness direction D of the sheet layer 2, a thin composite sheet 1 can be manufactured. This allows, for example, a composite sheet 1 having a thickness equal to the primary particle diameter of the particles 3 to be manufactured. Furthermore, by using the manufactured composite sheet 1 to bond the first object to be bonded 11 and the second object to be bonded 12, it becomes easier to control the separation distance between the first object to be bonded 11 and the second object to be bonded 12. This allows, for example, the separation distance between the first object to be bonded 11 and the second object to be bonded 12 to be maintained at the thickness equal to the primary particle diameter of the particles 3.

[0140] Furthermore, in the method for manufacturing a composite sheet according to this embodiment, when the particles 3 are arranged regularly, a composite sheet 1 suitable for joining to regularly arranged joining portions 11a, 12a can be manufactured.

[0141] Furthermore, in the manufacturing method of the composite sheet according to this embodiment, when particles 3 having at least one of thermal and electrical conductivity greater than that of the sheet layer 2 are used and the ratio of the projected area of ​​the particles 3 per unit area of ​​the composite sheet 1 as viewed in the thickness direction D of the sheet layer 2 is set to more than 15%, preferably 40% or more, more preferably 75% or more, the thermal and electrical conductivity of the composite sheet 1 as a whole can be improved.

[0142] Furthermore, in the method for producing a composite sheet according to this embodiment, when the thickness of the sheet layer 2 is equal to or less than the maximum length of the particles 3, it is possible to produce a composite sheet 1 in which the particles 3 are exposed from the sheet layer 2. In this way, by using the produced composite sheet 1 to bond the first object to be bonded 11 and the second object to be bonded 12, the particles 3 can be brought into direct contact with the first object to be bonded 11 and the second object to be bonded 12 without the sheet layer 2 interposed therebetween.

[0143] Furthermore, in the method for manufacturing a composite sheet according to this embodiment, when the particles 3 are exposed from the sheet layer 2, the manufactured composite sheet 1 is used to bond the first object to be joined 11 and the second object to be joined 12, thereby allowing the particles 3 to come into direct contact with the first object to be joined 11 and the second object to be joined 12 without going through the sheet layer 2.

[0144] Furthermore, in the method for producing a composite sheet according to this embodiment, if the surfaces of the particles 3 are solder, when the produced composite sheet 1 is used to join the first object to be joined 11 and the second object to be joined 12, by melting the solder, it is possible to increase the thermal and electrical conductivity between the first object to be joined 11 and the second object to be joined 12, and also to increase the bonding strength between the first object to be joined 11 and the second object to be joined 12.

[0145] Furthermore, in the method for producing a composite sheet according to the present embodiment, when the surfaces of the particles 3 are made of metal, the produced composite sheet 1 is used to join the first object to be joined 11 and the second object to be joined 12, thereby making it possible to increase the thermal and electrical conductivity between the first object to be joined 11 and the second object to be joined 12.

[0146] Furthermore, in the method for producing a composite sheet according to this embodiment, when the surfaces of the particles 3 are solder or metal, the surfaces of the particles are covered with an oxide film. However, since the sheet layer 2 contains a flux component, the oxide film can be removed by the flux component. This allows for high bonding characteristics to be obtained.

[0147] Furthermore, in the manufacturing method of the composite sheet according to this embodiment, the sheet layer 2 contains a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application. Therefore, when the manufactured composite sheet 1 is used to join the first object to be joined 11 and the second object to be joined 12, the sheet layer 2 can be pressed, heated, or ultrasonically applied to the sheet layer 2, thereby joining the first object to be joined 11 and the second object to be joined 12 by the sheet layer 2.

[0148] In the composite sheet 1 according to this embodiment, the particles 3 are distributed only within a certain range in the thickness direction D of the sheet layer 2, so that the inclination of the first object to be joined 11 and the second object to be joined 12 can be suppressed. This makes it possible to obtain high joining characteristics. Furthermore, since the separation distance between the first object to be joined 11 and the second object to be joined 12 can be easily controlled, for example, the separation distance between the first object to be joined 11 and the second object to be joined 12 can be maintained within the thickness range in the thickness direction D of the sheet layer 2 in which the particles 3 are distributed.

[0149] In another composite sheet 1 according to this embodiment, the particles 3 are arranged in a single layer that does not overlap in the thickness direction D of the sheet layer 2, so that the inclination of the first object to be joined 11 and the second object to be joined 12 can be suppressed. This makes it possible to obtain high joining characteristics. Furthermore, since it is easy to control the separation distance between the first object to be joined 11 and the second object to be joined 12, for example, the separation distance between the first object to be joined 11 and the second object to be joined 12 can be maintained at the thickness of the primary particle diameter of the particles 3.

[0150] Furthermore, in the composite sheet 1 according to this embodiment, when the thickness of the sheet layer 2 is equal to or less than the maximum length of the particles 3, the thickness of the composite sheet 1 can be set to the maximum length of the particles 3. This allows the composite sheet 1 to be thin. Furthermore, when the thickness of the sheet layer 2 is equal to or less than the maximum length of the particles 3, the particles 3 are exposed from the sheet layer 2. This allows the particles 3 to be in direct contact with the first object to be joined 11 and the second object to be joined 12 without the sheet layer 2 being interposed therebetween, thereby improving the bonding characteristics between the particles 3 and the first object to be joined 11 and the second object to be joined 12.

[0151] Furthermore, in the composite sheet 1 according to this embodiment, when the particles 3 are exposed from the sheet layer 2, the particles 3 can be brought into direct contact with the first object to be joined 11 and the second object to be joined 12 without going through the sheet layer 2.

[0152] Furthermore, in the composite sheet 1 according to this embodiment, when the particles 3 are regularly arranged, it is suitable for bonding to the first object to be bonded 11 and the second object to be bonded 12 which are also regularly arranged.

[0153] Furthermore, in the composite sheet 1 according to this embodiment, if the maximum length L of the particles 3 is equal to or greater than half the thickness of the sheet layer 2, when the first object to be joined 11 and the second object to be joined 12 are joined, the particles 3 can be easily brought into contact with the first object to be joined 11 and the second object to be joined 12.

[0154] Furthermore, in the composite sheet 1 according to this embodiment, when particles 3 having at least one of thermal and electrical conductivity greater than that of the sheet layer 2 are used and the ratio of the projected area of ​​the particles 3 per unit area of ​​the composite sheet 1 as viewed in the thickness direction D of the sheet layer 2 is greater than 15%, preferably 40% or more, and more preferably 75% or more, the conductivity of at least one of thermal and electrical conductivity of the composite sheet 1 as a whole can be improved.

[0155] Furthermore, in the composite sheet 1 according to this embodiment, when the surfaces of the particles 3 are solder, melting the solder can increase the thermal and electrical conductivity between the first object to be joined 11 and the second object to be joined 12, and can also increase the bonding strength between the first object to be joined 11 and the second object to be joined 12.

[0156] Furthermore, in the composite sheet 1 according to this embodiment, when the surfaces of the particles 3 are made of metal, the thermal and electrical conductivity between the first object to be joined 11 and the second object to be joined 12 can be increased.

[0157] Furthermore, in the composite sheet 1 according to this embodiment, if the surfaces of the particles 3 are solder or metal, the particles are covered with an oxide film. However, if the sheet layer 2 contains a flux component, the oxide film can be removed by the flux component. This allows for high bonding characteristics to be obtained.

[0158] Furthermore, in the composite sheet 1 according to this embodiment, when the sheet layer 2 contains a component that exhibits adhesive function by at least one of pressure, heat, and ultrasonic application, the sheet layer 2 can be pressurized, heated, or ultrasonically applied to join the objects to be joined by the sheet layer 2.

[0159] In the joining method according to this embodiment, any of the composite sheets 1 described above is placed between the first object to be joined 11 and the second object to be joined 12, and the first object to be joined 11 and the second object to be joined 12 are joined via the composite sheet 1, so that a joined body having high joining characteristics can be obtained.

[0160] Furthermore, in the bonding method according to this embodiment, when the surfaces of the particles 3 are solder, the particles 3 are covered with an oxide film. However, by placing the composite sheet 1 between the first object to be bonded 11 and the second object to be bonded 12 and applying pressure to the first object to be bonded 11 and the second object to be bonded 12 in the direction in which the first object to be bonded 11 and the second object to be bonded 12 face each other, the particles 3 are brought into contact with the first object to be bonded 11 and the second object to be bonded 12, and applying ultrasonic waves to at least one of the first object to be bonded 11 and the second object to be bonded 12, the oxide film present on the surfaces of the particles 3 is removed. In this case, for example, by subsequently performing a heating step or the like as necessary, the particles 3 can be easily bonded to the first object to be bonded 11 and the second object to be bonded 12.

[0161] Furthermore, in the bonding method according to this embodiment, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12 while the particle 3 is brought into contact with the portion to be bonded 11 a of the first object to be bonded 11 and the portion to be bonded 12 a of the second object to be bonded 12, thereby removing an oxide film present on the surface of the particle 3. In this case, for example, by subsequently performing a heating step or the like as necessary, the particle 3 can be easily bonded to the portion to be bonded 11 a of the first object to be bonded 11 and the portion to be bonded 12 a of the second object to be bonded 12.

[0162] Furthermore, in the bonding method according to this embodiment, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby melting the solder and bonding the particles 3 to at least one of the first object to be bonded 11 and the second object to be bonded 12. In this case, the particles 3 can be bonded to the first object to be bonded 11 and the second object to be bonded 12 without a subsequent heating step.

[0163] Furthermore, in the bonding method according to this embodiment, ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, thereby forming clean surfaces on the surfaces of the particles 3, the surfaces of the parts to be bonded 11a, and the surfaces of the parts to be bonded 12a, and solid-state bonding is performed between the particles 3 and the parts to be bonded 11a and 12a. In this case, the particles 3 can be bonded to the parts to be bonded 11a of the first object to be bonded 11 and the parts to be bonded 12a of the second object to be bonded 12 without a subsequent heating step.

[0164] Furthermore, in the bonding method according to this embodiment, when the surfaces of the particles 3 are metal, the particles 3 are covered with an oxide film. However, by placing the composite sheet 1 between the first object to be bonded 11 and the second object to be bonded 12 and applying pressure to the first object to be bonded 11 and the second object to be bonded 12 in the direction in which the first object to be bonded 11 and the second object to be bonded 12 face each other, the particles 3 come into contact with the portions 11 a of the first object to be bonded 11 and the portions 12 a of the second object to be bonded 12. Ultrasonic waves are applied to at least one of the first object to be bonded 11 and the second object to be bonded 12, smoothing the bonding surfaces between the particles 3 and at least one of the portions 11 a and 12 a. In this case, the contact area between the portions 11 a and 12 a and the particles 3 is increased, thereby improving the thermal and electrical conductivity between the first object to be bonded 11 and the second object to be bonded 12.

[0165] Furthermore, in the bonding method according to this embodiment, when the surfaces of the particles 3, the portions to be bonded 11a, and the portions to be bonded 12a are made of metal, the particles 3, the portions to be bonded 11a, and the portions to be bonded 12a are covered with an oxide film. However, by placing the composite sheet 1 between the first object to be bonded 11 and the second object to be bonded 12 and applying pressure to the first object to be bonded 11 and the second object to be bonded 12 in the direction in which the first object to be bonded 11 and the second object to be bonded 12 face each other, the particles 3 are brought into contact with the portions to be bonded 11a of the first object to be bonded 11 and the portions to be bonded 12a of the second object to be bonded 12, and applying ultrasonic waves to at least one of the first object to be bonded 11 and the second object to be bonded 12, the oxide film present on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a, and the surfaces of the portions to be bonded 12a is removed, forming clean surfaces on the surfaces of the particles 3, the surfaces of the portions to be bonded 11a, and the surfaces of the portions to be bonded 12a, and thereby solid-state bonding is performed between the particles 3 and the portions to be bonded 11a and 12a. In this case, even without a subsequent heating step, the particles 3 can be bonded to the bonded portions 11 a of the first body to be bonded 11 and the bonded portions 12 a of the second body to be bonded 12. Furthermore, the bonding strength between the particles 3 and the bonded portions 11 a of the first body to be bonded 11 and the bonded portions 12 a of the second body to be bonded 12 can be increased.

[0166] Furthermore, in the bonding method according to this embodiment, when the surfaces of the particles 3, the bonded portions 11a, and the bonded portions 12a are metal, the particles 3, the bonded portions 11a, and the bonded portions 12a are covered with an oxide film. However, by placing the composite sheet 1 between the bonded portions 11a of the first object to be bonded 11 and the bonded portions 12a of the second object to be bonded 12, and applying pressure to the first object to be bonded 11 and the second object to be bonded 12 in the direction in which the first object to be bonded 11 and the second object to be bonded 12 face each other, the oxide film present on the surfaces of the particles 3, the surfaces of the bonded portions 11a, and the surfaces of the bonded portions 12a is removed by the flux components. In this case, for example, by subsequently performing a heating process or the like as necessary, the particles 3 can be easily bonded to the bonded portions 11a of the first object to be bonded 11 and the bonded portions 12a of the second object to be bonded 12.

[0167] Furthermore, in the bonding method according to this embodiment, when the surface of the particle 3, the bonded portion 11a, and the bonded portion 12a are metal, the surface of the particle 3, the bonded portion 11a, and the bonded portion 12a are covered with an oxide film. However, by placing the composite sheet 1 between the parts to be joined 11 a of the first object to be joined 11 and the parts to be joined 12 a of the second object to be joined 12, and applying pressure to the first object to be joined 11 and the second object to be joined 12 in the direction in which the first object to be joined 11 and the second object to be joined 12 face each other, the particles 3 are brought into contact with the parts to be joined 11 a of the first object to be joined 11 and the parts to be joined 12 a of the second object to be joined 12, and the oxide films present on the surfaces of the particles 3, the parts to be joined 11 a, and the parts to be joined 12 a are removed by the flux component, and ultrasonic waves are applied to at least one of the first object to be joined 11 and the second object to be joined 12, removing the oxide films present on the surfaces of the particles 3, the parts to be joined 11 a, and the parts to be joined 12 a, forming clean surfaces on the surfaces of the particles 3, the parts to be joined 11 a, and the parts to be joined 12 a, and thereby solid-state bonding is performed between the particles 3 and the parts to be joined 11 a and 12 a. In this case, even without a subsequent heating step, the particles 3 can be bonded to the bonded portions 11 a of the first body to be bonded 11 and the bonded portions 12 a of the second body to be bonded 12. Furthermore, the bonding strength between the particles 3 and the bonded portions 11 a of the first body to be bonded 11 and the bonded portions 12 a of the second body to be bonded 12 can be increased.

[0168] Furthermore, in the bonding method according to this embodiment, if a flux component is applied to the surface of at least one of the composite sheet 1, the first object to be bonded 11, and the second object to be bonded 12 before pressurizing the first object to be bonded 11 and the second object to be bonded 12, the flux component can remove the oxide film present on the surface of the particles 3. This allows the output of ultrasonic waves to be reduced. Even if ultrasonic waves are not applied thereafter, for example, by performing a heating step or the like as necessary, the particles 3 can be easily bonded to the bonded portions 11 a of the first object to be bonded 11 and the bonded portions 12 a of the second object to be bonded 12.

[0169] Furthermore, in the bonding method according to this embodiment, when ultrasonic waves are applied to at least one of the first body to be bonded 11 and the second body to be bonded 12 in a reducing environment, the output of the ultrasonic waves can be reduced.

[0170] Furthermore, in the bonding method according to this embodiment, when the first object to be bonded 11 has the portion to be bonded 11a arranged at a specific position and the particle 3 is arranged at a position corresponding to the portion to be bonded 11a, the first object to be bonded 11 and the second object to be bonded 12 can be easily bonded to the particle 3.

[0171] In the bonding method according to this embodiment, the first and second objects to be bonded 11 and 12 have bonded portions 11a and 12a on which recesses 11c and 12c are formed, the particles 3 are arranged at positions corresponding to the recesses 11c and 12c and are larger than the recesses 11c and 12c, the composite sheet 1 is placed between the bonded portions 11a of the first objects to be bonded 11 and the bonded portions 12a of the second objects to be bonded 12, and the first and second objects to be bonded 11 and 12 are pressed in the direction in which the first and second objects to be bonded 11 and 12 face each other, thereby forcing the particles into the recesses 11c and 12c. In this case, the bonding strength between the particles 3 and the first and second objects to be bonded 11 and 12 can be increased by the pressure between the particles 3 and the recesses 11c and 12c and the stress due to compressive deformation of the particles 3 and the recesses 11c and 12c.

[0172] Furthermore, in the bonding method according to this embodiment, the first object to be bonded 11 and the second object to be bonded 12 have the object to be bonded 11a and the object to be bonded 12a, on which the recesses 11c and 12c are formed, the particles 3 are arranged at positions corresponding to the recesses 11c and 12c, and are smaller than the recesses 11c and 12c, the thermal expansion coefficient of the particles 3 is larger than the linear expansion coefficient of the object to be bonded 11a of the first object to be bonded 11 and the object to be bonded 12a of the second object to be bonded 12, the surfaces of the particles 3 and the surfaces of the recesses 11c and 12c are metal, the composite sheet 1 is arranged between the object to be bonded 11a of the first object to be bonded 11 and the object to be bonded 12a of the second object to be bonded 12, the particles 3 are inserted into the recesses 11c and 12c, and the first object to be bonded 11 and the second object to be bonded 12 are heated while being pressurized in a direction in which the first object to be bonded 11 and the second object to be bonded 12 face each other, thereby diffusion bonding the particles 3 to the recesses 11c and 12c. In this case, the bonding strength between the particle 3 and the first object to be bonded 11 and the second object to be bonded 12 can be increased.

[0173] Furthermore, in the bonding method according to this embodiment, the composite sheet 1 is inspected before the bonding step, and the first and second objects 11 and 12 are not bonded together using a composite sheet 1 that is determined to be defective, while the first and second objects 11 and 12 are bonded together using a composite sheet 1 that is determined to be non-defective. In this case, the occurrence of defective bonded bodies 9 can be reduced.

[0174] In the bonding method according to this embodiment, the first bonded body 11 has the bonded portions 11a arranged in specific positions, the particles 3 are arranged in positions corresponding to the bonded portions 11a, and the inspection step involves visually inspecting the arrangement of the particles 3. In this case, it is possible to prevent the generation of defective bonded bodies 9 due to improper arrangement of the particles 3.

[0175] In the bonding method according to this embodiment, a first object to be bonded 11 is bonded to a composite sheet 1 determined to be a non-defective product, and then a second object to be bonded 12 is bonded to the surface of the composite sheet 1 opposite to the surface to which the first object to be bonded 11 is bonded. In this case, the first object to be bonded 11 and the second object to be bonded 12 can be easily bonded.

[0176] In the bonded body 9 according to this embodiment, the first bonded body 11 and the second bonded body 12 are bonded via any one of the composite sheets 1 described above, and therefore, high bonding characteristics can be obtained.

[0177] The present disclosure is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present disclosure.

[0178] DESCRIPTION OF SYMBOLS 1...composite sheet, 2...sheet layer, 2a...first surface, 2b...second surface, 3...particle, 4...second sheet, 5...third sheet, 6...roller, 7...elastic roller, 9...bonded body, 11...first bonded body, 11a...bonded portion, 11c...recess, 12...second bonded body, 12a...bonded portion, 12c...recess, 21...first sheet layer, 22...second sheet layer, 23...substrate layer, 24...substrate layer, 25...peel layer, 26...peel layer, 31...oxide film, 32...oxide film, 100...bonding device, 101...visual inspection device, 102...arm, D...thickness direction, F...flux component

Claims

1. A method for producing a composite sheet having particles contained in a sheet layer, comprising: arranging particles on the surface of a sheet layer formed into a sheet shape; and applying pressure in the thickness direction of the sheet layer to embed the particles in the sheet layer.

2. A method for producing a composite sheet in which particles are contained in sheet layers, comprising: arranging particles on the surface of a first sheet layer that is formed into a sheet shape and that forms a part of the sheet layer; arranging a second sheet layer that is formed into a sheet shape and that forms a part of the sheet layer on the surface of the first sheet layer on which the particles are arranged; and applying pressure to the first sheet layer and the second sheet layer in opposing directions to embed the particles in at least one of the first sheet layer and the second sheet layer.

3. The method for producing a composite sheet according to claim 1 or 2, wherein the particles are distributed only within a certain range in the thickness direction of the sheet layer.

4. The method for producing a composite sheet according to claim 1 or 2, wherein the maximum length of the particles is at least half the thickness of the sheet layer.

5. The method for producing a composite sheet according to claim 1 or 2, wherein the particles are arranged in a single layer that does not overlap in the thickness direction of the sheet layer.

6. The method for producing a composite sheet according to claim 5, wherein the particles are regularly arranged.

7. A method for producing a composite sheet according to claim 1 or 2, wherein the particles have greater thermal and / or electrical conductivity than the sheet layer, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer is greater than 15%.

8. The method for producing a composite sheet according to claim 1 or 2, wherein the thickness of the sheet layer is equal to or less than the maximum length of the particles.

9. The method for producing a composite sheet according to claim 1 or 2, wherein the particles are exposed from the sheet layer.

10. The method for producing a composite sheet according to claim 1 or 2, wherein the surfaces of the particles are solder.

11. The method for producing a composite sheet according to claim 1 or 2, wherein the surfaces of the particles are metallic.

12. The method for producing a composite sheet according to claim 10, wherein the sheet layer contains a flux component.

13. A method for producing a composite sheet according to claim 1 or 2, wherein the sheet layer contains a component that exhibits adhesive properties when subjected to at least one of pressure, heat, and ultrasonic application.

14. A composite sheet having particles contained in a sheet layer, wherein the particles are distributed only within a certain range in the thickness direction of the sheet layer.

15. A composite sheet having particles contained in a sheet layer, wherein the particles are arranged in a single layer that does not overlap in the thickness direction of the sheet layer.

16. The composite sheet according to claim 15, wherein the thickness of the sheet layer is equal to or less than the maximum length of the particles.

17. The composite sheet according to claim 15, wherein the particles are exposed from the sheet layer.

18. The composite sheet according to claim 15, wherein the particles are regularly arranged.

19. A composite sheet according to claim 14 or 15, wherein the maximum length of the particles is at least half the thickness of the sheet layer.

20. A composite sheet according to claim 14 or 15, wherein the particles have a higher thermal and / or electrical conductivity than the sheet layer, and the ratio of the projected area of ​​the particles per unit area of ​​the composite sheet as viewed in the thickness direction of the sheet layer is greater than 15%.

21. A composite sheet according to claim 14 or 15, wherein the surfaces of the particles are solder.

22. The composite sheet according to claim 14 or 15, wherein the surface of the particles is metallic.

23. The composite sheet according to claim 21, wherein the sheet layer contains a flux component.

24. A composite sheet according to claim 14 or 15, wherein the sheet layer contains a component that exhibits adhesive properties when subjected to at least one of pressure, heat, and ultrasonic waves.

25. The composite sheet according to claim 14 or 15, further comprising a second sheet laminated to the particle-containing sheet layer.

26. The composite sheet according to claim 25, wherein the sheet layer is laminated to at least one of both surfaces of the second sheet.

27. The composite sheet according to claim 14 or 15, further comprising a third sheet having the particle-containing sheet layer as an inner layer.

28. The composite sheet according to claim 14 or 15, wherein a plurality of the particle-containing sheet layers are laminated.

29. A joining method comprising a joining step of placing the composite sheet according to claim 14 or 15 between a first object to be joined and a second object to be joined, and joining the first object to be joined and the second object to be joined via the composite sheet.

30. The bonding method according to claim 29, wherein the surfaces of the particles are solder, and in the bonding step, the composite sheet is placed between the first and second objects to be bonded, the first and second objects to be bonded are pressed in the opposing direction of the first and second objects to be bonded, thereby bringing the particles into contact with the first and second objects to be bonded, and ultrasonic waves are applied to at least one of the first and second objects to be bonded, thereby removing an oxide film present on the surfaces of the particles.

31. The bonding method according to claim 30, wherein the first and second objects to be bonded have metal bonded portions, and in the bonding step, an ultrasonic wave is applied to at least one of the first and second objects to be bonded while the particles are in contact with the bonded portions of the first and second objects to be bonded, thereby removing an oxide film present on the surface of the bonded portions.

32. The bonding method according to claim 30, wherein in the bonding step, ultrasonic waves are applied to at least one of the first object to be bonded and the second object to be bonded, thereby melting the solder and bonding the particles to the first object to be bonded and the second object to be bonded.

33. The bonding method according to claim 30, wherein the first and second objects to be bonded have metal bonded parts, and in the bonding step, ultrasonic waves are applied to at least one of the first and second objects to be bonded to form clean surfaces on the surfaces of the particles and the surfaces of the bonded parts, thereby solid-state bonding the particles and the bonded parts.

34. The bonding method according to claim 29, wherein the surfaces of the particles are metallic, the first and second objects to be bonded have metal bonded portions, and in the bonding step, the composite sheet is placed between the first and second objects to be bonded, the first and second objects to be bonded are pressurized in a direction in which the first and second objects to be bonded face each other, thereby bringing the particles into contact with the bonded portions of the first and second objects to be bonded, and ultrasonic waves are applied to at least one of the first and second objects to be bonded, thereby smoothing the bonding surfaces between the particles and the bonded portions.

35. The bonding method according to claim 29, wherein the surfaces of the particles are metallic, the first and second objects to be bonded have metallic bonded portions, and the bonding step comprises: arranging the composite sheet between the first and second objects to be bonded; pressurizing the first and second objects to be bonded in a direction in which the first and second objects to be bonded face each other, thereby bringing the particles into contact with the bonded portions of the first and second objects to be bonded; applying ultrasonic waves to at least one of the first and second objects to be bonded, thereby removing oxide films present on the surfaces of the particles and the surfaces of the bonded portions, forming clean surfaces on the surfaces of the particles and the surfaces of the bonded portions, and solid-state bonding the particles and the bonded portions.

36. A joining method according to claim 29, wherein the surfaces of the particles are metallic, the first and second objects to be joined have metallic joined portions, the sheet layer of the composite sheet contains a flux component, and in the joining step, the composite sheet is placed between the joined portions of the first objects to be joined and the joined portions of the second objects to be joined, and the first and second objects to be joined are pressed in a direction in which the first and second objects to be joined face to face, thereby removing oxide films present on the surfaces of the particles and the surfaces of the joined portions by the flux component.

37. The joining method according to claim 29, wherein the surfaces of the particles are metallic, the first and second objects to be joined have metallic parts to be joined, the sheet layer of the composite sheet contains a flux component, and in the joining step, the composite sheet is placed between the parts to be joined of the first objects to be joined and the parts to be joined of the second objects to be joined, the first and second objects to be joined are pressed in a direction in which the first and second objects to be joined face to face, thereby bringing the particles into contact with the parts to be joined of the first and second objects to be joined and removing oxide films present on the surfaces of the particles and the parts to be joined by the flux component, and ultrasonic waves are applied to at least one of the first and second objects to be joined, thereby removing oxide films present on the surfaces of the particles and the parts to be joined and forming clean surfaces, and the particles and the parts to be joined are solid-state joined.

38. The joining method according to claim 30, wherein in the joining step, a flux component is applied to a surface of at least one of the composite sheet, the first object to be joined, and the second object to be joined before pressurizing the first object to be joined and the second object to be joined.

39. The bonding method according to claim 30, wherein the bonding step applies ultrasonic waves to at least one of the first and second objects to be bonded in a reducing environment.

40. The bonding method according to claim 29, wherein the first object to be bonded has portions to be bonded arranged at specific positions, and the particles are arranged at positions corresponding to the portions to be bonded.

41. The bonding method according to claim 29, wherein the first and second objects to be bonded have bonded portions with recesses formed therein, the particles are arranged at positions corresponding to the recesses and are larger than the recesses, and in the bonding step, the composite sheet is arranged between the bonded portions of the first objects to be bonded and the bonded portions of the second objects to be bonded, and the first and second objects to be bonded are pressed in a direction in which the first and second objects to be bonded face each other, thereby forcing the particles into the recesses.

42. The bonding method according to claim 29, wherein the first and second objects to be bonded have bonded portions with recesses formed therein, the particles are arranged at positions corresponding to the recesses and are smaller than the recesses, the thermal expansion coefficient of the particles is greater than the linear expansion coefficient of the bonded portions of the first and second objects to be bonded, the surfaces of the particles and the surfaces of the recesses are metallic, and in the bonding step, the composite sheet is arranged between the bonded portions of the first objects to be bonded and the bonded portions of the second objects to be bonded, the particles are inserted into the recesses, and the first and second objects to be bonded are heated while being pressurized in directions in which the first and second objects to be bonded face each other, thereby diffusion bonding the particles and the recesses.

43. A joining method according to claim 29, further comprising an inspection step of inspecting the composite sheet before the joining step, wherein in the joining step, the first and second objects to be joined are not joined using a composite sheet determined to be defective in the inspection step, and the first and second objects to be joined are joined using a composite sheet determined to be non-defective in the inspection step.

44. The bonding method according to claim 43, wherein the first object to be bonded has portions to be bonded arranged at specific positions, the particles are arranged at positions corresponding to the portions to be bonded, and the inspection step visually inspects the arrangement of the particles.

45. A bonding method according to claim 43, wherein in the bonding step, the first bonded object is bonded to the composite sheet determined to be non-defective in the inspection step, and then the second bonded object is bonded to the surface of the composite sheet opposite to the first bonded object.

46. ​​A bonded body in which a first object to be bonded and a second object to be bonded are bonded via the composite sheet according to claim 14 or 15.

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