Method for manufacturing a bonded body and method for manufacturing an insulating circuit board

Abstract

In joining a laminate of a plurality of different materials including a metal plate in a pressurized and heated state, a first pressing member in which a first metal foil / carbon sheet or ceramic sheet / graphite sheet is sequentially laminated is arranged so that the first metal foil contacts the surface of a first metal plate of the laminate, the first metal foil is formed of a material that does not react with the first plate member at the contact surface of the first metal foil when heated, and the product of the Young's modulus (GPa) and the thickness (mm) of the first metal foil is 0.6 or greater but 100 or less, a good joint can be produced by uniformly pressurizing the laminate, and the attachment of foreign matter to the surface of the laminate can be suppressed.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a bond formed from multiple different metal plates, such as a power module substrate with a two-layer circuit structure, and more particularly to a method suitable for bonding metal plates together by solid-state diffusion bonding, and a method for manufacturing an insulating circuit board using this method. This application claims priority to Japanese Patent Application No. 2020-052827, filed on March 24, 2020, the contents of which are incorporated herein by reference. Background Technology

[0002] Regarding power module substrates (insulated circuit boards), a common construction involves forming a circuit layer on one side of a ceramic substrate that serves as an insulating layer, and forming a heat dissipation layer on the other side.

[0003] As a substrate for this power module, for example, the power module substrate disclosed in Patent Document 1. In this power module substrate, metal plates made of aluminum or aluminum alloy, or copper or copper alloy, are soldered to both sides of a ceramic substrate, thereby forming a circuit layer on one side of the ceramic substrate and a heat dissipation layer on the other side. A heat sink made of aluminum or aluminum alloy, or copper or copper alloy, is bonded to the heat dissipation layer.

[0004] In this power module substrate, a ceramic substrate and a metal plate are bonded together by pressurizing and heating these laminates using a pressurizing device. At this time, a spacer formed by stacked carbon and graphite layers is positioned between the laminates and the pressurizing device. The carbon layer is located on the laminate side.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-63145

[0006] As a substrate for such power modules, the circuit layer is sometimes formed as a two-layer structure of aluminum and copper. In order to manufacture a joint formed of multiple different metal plates, a copper plate is bonded to an aluminum layer formed on a ceramic substrate to form a copper layer by the method described in Patent Document 1. However, in the bonding of aluminum and copper, solid-phase diffusion bonding is sometimes performed without the use of solder to apply pressure and heat.

[0007] At this point, compared to bonding by brazing filler metal, more uniform pressure is required. However, in the pressure device described in Patent Document 1, since the side of the spacer that contacts the laminate is formed by a carbon layer, the displacement caused by the load applied during pressure application is small. In cases where there are small irregularities or large flatness on the surface of the laminate, the pressure may not be applied evenly, resulting in poor bonding.

[0008] Furthermore, if the surface of the spacer that contacts the laminate is formed of a carbon layer, localized delamination may occur when the carbon layer and the laminate are heated and pressurized together, and a portion of the carbon layer may adhere to the surface of the laminate. Even micro-etching on the surface of the bonding assembly cannot completely remove this foreign matter, leading to problems such as the inability to mount semiconductor components on the laminated assembly (on the circuit layer).

[0009] On the other hand, if a strong etching process is performed to remove foreign matter, the surface of the laminated material after bonding will become rough, and it will be impossible to mount semiconductor components on the circuit layer. Summary of the Invention

[0010] This invention was made in view of this situation, in which a good bond is produced by uniformly pressing the laminate of multiple different metal plates under pressure and heat, while suppressing the adhesion of foreign matter to the surface of the laminate. Furthermore, the object is to manufacture an insulating circuit board using this manufacturing method.

[0011] Regarding the manufacturing method of the joint of the present invention, the joint is manufactured by pressing and heating a laminate of a first plate component and a second plate component. The first plate component includes a first metal plate. A first pressing component, on which a first metal foil / carbon sheet or a ceramic sheet / graphite sheet is sequentially laminated, is arranged such that the first metal foil is in contact with the surface of the first plate component. The first metal foil is formed of a material that does not react with the first plate component at the contact surface of the first metal foil when heated. The product of the Young's modulus (GPa) and the thickness (mm) of the first metal foil is 0.6 or more and 100 or less.

[0012] In addition, the Young's modulus and thickness in this invention are values ​​at 25°C.

[0013] By using a first metal foil formed of a material that does not react with the surface of the first metal plate of the laminate when heated, it is possible to suppress the adhesion of a portion of the carbon sheet or ceramic sheet to the surface of the laminate (first metal plate) when the laminate is pressurized and heated by the first metal foil.

[0014] Furthermore, the first metal foil deforms by absorbing gaps caused by minute irregularities and flatness on the surface of the laminate using its ductility, thus enabling the laminate to be uniformly loaded and manufactured into a bonded body with uniform bonding across its entire surface. Moreover, by placing a soft graphite sheet on the back of a hard carbon or ceramic sheet, the conformability of the first metal foil to the surface shape of the laminate can be further improved, and the bonding strength can be enhanced.

[0015] By setting the product of the Young's modulus (GPa) and the thickness (mm) of the first metal foil to 0.6 or more and 100 or less, it can be pressed onto the entire surface of the laminate by locally bending in a manner that follows the surface shape of the laminate, thus enabling the plate components to be joined together with high precision.

[0016] Moreover, there is no possibility of the first metal foil breaking or a portion of the metal foil peeling off and adhering to the laminate when pressure is applied, which can suppress the breakage of carbon or ceramic sheets and produce high-quality joints with fewer defective products.

[0017] Furthermore, if the product of Young's modulus (GPa) and thickness (mm) exceeds 100, the conformability to the surface shape of the laminate of the first metal foil will be impaired, resulting in poor bonding. If it is less than 0.6, the metal foil will break, and carbon or ceramic will adhere to the surface of the laminate.

[0018] In this invention, a second pressing member, on which a second metal foil / carbon sheet or a ceramic sheet / graphite sheet is sequentially stacked, is configured such that the second metal foil is in contact with the surface of the second plate member. The second metal foil is formed of a material that does not react with the second plate member at the contact surface of the second metal foil when heated. The product of the Young's modulus (GPa) and the thickness (mm) of the second metal foil can be 0.6 or more and 100 or less.

[0019] By placing metal foils made of a material that does not react with the surface of the laminate on both sides of the laminate, it is possible to reliably suppress the adhesion of a portion of the carbon sheet or ceramic sheet to the surface of the laminate.

[0020] In this invention, either the first plate component or the second plate component may be formed of copper or a copper alloy, and the other may be formed of aluminum or an aluminum alloy.

[0021] Aluminum and copper are typically bonded by solid-phase diffusion, and this invention is particularly effective when bonding is performed in this solid-phase manner.

[0022] Furthermore, the present invention does not exclude the use of liquid phase bonding with brazing filler metal. For example, the first plate component is formed of a metal plate, and the second plate component is formed of a ceramic substrate; these can also be applied to cases where brazing filler metal bonding is used.

[0023] The method for manufacturing the insulating circuit board of the present invention uses the above-described method for manufacturing the bonding body. The first board component is formed of a first metal plate, which is formed of copper or a copper alloy. The second board component is formed of a ceramic substrate and a second metal plate. The second metal plate is bonded to one side of the ceramic substrate and is formed of aluminum or an aluminum alloy. The first metal plate is stacked on the second metal plate bonded to the ceramic substrate to form the laminate. The first metal plate and the second metal plate are solid-phase diffusion bonded while the first metal foil is in contact with the first metal plate.

[0024] The method for manufacturing the insulating circuit board of the present invention uses the above-described method for manufacturing the bonding body. The first board component is formed by laminating a first metal plate made of copper or a copper alloy and an AlSiC composite material. The AlSiC composite material is formed by impregnating a metal with aluminum as the main component in a porous silicon carbide body. The second board component is formed by a ceramic substrate, a second metal plate, and the first metal plate. The second metal plate is bonded to both sides of the ceramic substrate and is formed of aluminum or an aluminum alloy. The first metal plate is laminated on one side of the second metal plate. The first board component and the second board component are laminated by contacting the second metal plate on the other side of the second board component with the first metal plate of the first board component to form the laminate. In a state where the first metal foil of the first pressing member is in contact with the AlSiC composite material of the laminate, and the second metal foil of the second pressing member is in contact with the surface of the first metal plate of the second board component, the first metal plate and the second metal plate, and the first metal plate and the AlSiC composite material are simultaneously subjected to solid-phase diffusion bonding.

[0025] According to the manufacturing method of the joint of the present invention, when a laminate of multiple different plate components is pressed and joined under heating, a uniform pressure can be applied to the laminate to produce a good joint, and foreign matter is suppressed from adhering to the surface of the laminate. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of a power module substrate, which is an embodiment of the bonding body (insulating circuit board) of the present invention.

[0027] Figure 2 It means Figure 1 A cross-sectional view (1) of the manufacturing process of the power module substrate.

[0028] Figure 3 It means Figure 1 A cross-sectional view (2) of the manufacturing process of the power module substrate.

[0029] Figure 4 It is used for Figure 2 and Figure 3 A front view of the pressurization device used in the manufacturing method.

[0030] Figure 5 Is Figure 4 A cross-sectional view of the spacer used in the pressurization device.

[0031] Figure 6 This is a scanning electron microscope (SEM) image of the circuit layer surface of sample No.2 in the embodiment.

[0032] Figure 7 This is a SEM image of the circuit layer surface of sample No.1 in the embodiment.

[0033] Figure 8 This is a cross-sectional view showing the manufacturing process of a substrate for another power module. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0035] This embodiment is an example of a power module substrate 1, which serves as an example of an insulating circuit board (joint). For example... Figure 1 As shown, the power module substrate 1 includes: a ceramic substrate 10, a circuit layer 20 bonded to one side of the ceramic substrate 10, and a heat dissipation layer 30 bonded to the other side of the ceramic substrate 10.

[0036] The ceramic substrate 10 can be, for example, nitride-based ceramics such as AlN (aluminum nitride) or Si3N4 (silicon nitride), or oxide-based ceramics such as Al2O3 (alumina). Furthermore, the thickness of the ceramic substrate 10 is 0.2 mm or more and 1.5 mm or less.

[0037] The circuit layer 20 and the heat dissipation layer 30 are both two-layer structures, namely, a second metal layer 41 formed of aluminum or aluminum alloy and a first metal layer 42 formed of copper or copper alloy. In other words, in the power module substrate 1, a second metal layer 41 is formed on both sides of the ceramic substrate 10, and a first metal layer 42 is formed on the second metal layer 41.

[0038] The second metal layer 41 can be made of pure aluminum with a purity of 99% by mass or higher (e.g., pure aluminum of the 1000 series in JIS standards, especially 1N90 (purity of 99.9% by mass or higher: so-called 3N aluminum), or 1N99 (purity of 99.99% by mass or higher: so-called 4N aluminum)) and aluminum alloys such as A6063 series. In order to buffer the difference in thermal expansion and contraction between the first metal layer 42 and the ceramic substrate 10, pure aluminum is preferably used as the second metal layer 41.

[0039] The first metal layer 42 is preferably copper (oxygen-free copper) with a purity of 99.96% by mass or higher, or copper (tough copper) with a purity of 99.90% by mass or higher.

[0040] The thickness of the second metal layer 41 and the first metal layer 42 is not limited. For example, the second metal layer 41 can be 0.1 mm or more and 2.0 mm or less, and the first metal layer 42 can be 0.2 mm or more and 5.0 mm or less. The second metal layer 41 and the first metal layer 42 can be of the same thickness in the circuit layer 20 and the heat dissipation layer 30, or they can be a combination of different thicknesses. In the illustrated example, the second metal layer 41 and the first metal layer 42 in the circuit layer 20 and the heat dissipation layer 30 are labeled with the same reference numerals without distinction.

[0041] The manufacturing method of the power module substrate 1 configured in this way will be described.

[0042] First, such as Figure 2 As shown, a second metal plate 41a made of aluminum or aluminum alloy is laminated on both sides of a ceramic substrate 10 using solder 50, and the laminate is pressurized and heated to bond the ceramic substrate 10 and the second metal plate 41a together, thereby forming a second metal layer 41 on both sides of the ceramic substrate 10 (first bonding process).

[0043] Next, as Figure 3 As shown, a first metal plate 42a made of copper or copper alloy is stacked on the second metal layer 41, and the stack is pressurized and heated to solid-phase diffusion bond aluminum and copper, thereby forming the first metal layer 42 on the second metal layer 41 (second bonding process).

[0044] In the first bonding process, the second metal plate 41a corresponds to the first plate component of the present invention, and the ceramic substrate 10 corresponds to the second plate component of the present invention. On the other hand, in the second bonding process, the first metal plate 42a corresponds to the first plate component of the present invention, and the ceramic substrate 10 and the second metal plate 41a (second metal layer 41) bonded to one side of the ceramic substrate 10 correspond to the second plate component of the present invention.

[0045] In this manufacturing method, in order to pressurize the laminate in the first bonding process and the laminate in the second bonding process, a method is used... Figure 4 The pressure device 110 shown. Hereinafter, the laminate in the first bonding process (the laminate formed by the ceramic substrate 10 and the two second metal plates 41a) and the laminate in the second bonding process (the laminate formed by the ceramic substrate 10 with two second metal layers 41 and the first metal plate 42a) are described as laminate S without distinction.

[0046] The pressurizing device 110 includes: a base plate 111, guide posts 112 vertically mounted on the upper corners of the base plate 111, a fixing plate 113 fixed to the upper ends of the guide posts 112, a pressing plate 114 supported by the guide posts 112 in a manner that allows it to move freely up and down between the base plate 111 and the fixing plate 113, and a force-applying part 115 (such as a spring) disposed between the fixing plate 113 and the pressing plate 114 and applying force downward to the pressing plate 114.

[0047] The fixing plate 113 and the pressing plate 114 are arranged parallel to the base plate 111, and a laminate S is provided between the base plate 111 and the pressing plate 114.

[0048] In the base plate 111 and the pressing plate 114, a spacer 60 is provided on the side that contacts the laminate S to make the pressure uniform.

[0049] Each spacer 60 corresponds to the first pressing member and the second pressing member of the present invention, such as Figure 5 As shown, the structure consists of graphite sheets 61, carbon sheets 62, and metal foils (first metal foil or second metal foil) 63 stacked in sequence.

[0050] Graphite sheet 61 is constructed by stacking multiple flake-like graphite films, such as mica, of a soft, cushioning graphite material. It is made by acid-treating natural graphite, shaping it into sheets, and then rolling it. This graphite sheet 61 is soft and has a bulk density of 0.5 mg / m³. 3 Above and 1.3Mg / m 3 The following are examples. For instance, T-5 (thermal conductivity: 75.4 W / mK, elastic modulus: 11.4 GPa) manufactured by ASAHI-GRAPHITE and PF (compression ratio: 47%, recovery rate: 14%) graphite sheets manufactured by Toyo Tanso Co., Ltd. can be used.

[0051] Carbon sheet 62 is formed into a flat plate shape from a heat-resistant hard carbon material and fired at a high temperature of approximately 3000℃. Carbon sheet 62 has a bulk density of 1.6 Mg / m³. 3 Above and 1.9Mg / m 3 The following are relatively hard carbon sheets that are formed into a smooth plane. For example, G-347 manufactured by ASAHI-GRAPHITE (thermal conductivity: 116 W / mK, elastic modulus: 10.8 GPa) can be used.

[0052] The metal foil 63 corresponds to the first and second metal foils of the present invention and is formed of a material that does not react with the surface of the laminate S when heated. When the first metal plate 42a disposed on both sides of the laminate S is formed of copper or a copper alloy, the metal foil 63 is preferably made of copper or a copper alloy, or stainless steel. Furthermore, the non-reactive material refers to a material that does not peel off when cooled from the bonding temperature to room temperature and does not form intermetallic compounds between the metal foil and the surface of the laminate.

[0053] The thickness of the spacer 60 is not particularly limited. For example, the graphite sheet 61 is 0.5 mm or more and 5.0 mm or less, the carbon sheet 62 is 0.5 mm or more and 2.0 mm or less, and the metal foil 63 is 0.005 mm or more and 0.15 mm or less.

[0054] Regarding the metal foil 63, as described above, any suitable metal can be selected as long as it does not react with the surface of the laminate S (in this case, copper) when heated. However, the product of Young's modulus (GPa) and thickness (mm) is set to be 0.6 or higher and 100 or lower. This is because if the product is less than 0.6, the metal foil 63 will break, and carbon will adhere to the surface of the laminate S. If it exceeds 100, the conformability to the surface shape of the laminate S will be impaired, resulting in poor bonding.

[0055] In addition, the Young's modulus (GPa) and thickness are values ​​at room temperature (25°C).

[0056] Furthermore, although carbon sheet 62 is used in this embodiment, it is not limited to this; any hard material that does not deform when heated can be used, such as ceramic sheet. The ceramic sheet is, for example, a sintered body formed from various ceramics such as aluminum nitride, silicon nitride, and alumina. Specifically, an example is an Al2O3 ceramic sintered body sheet manufactured by MARUWA CO.,LTD. The thickness of the ceramic sheet can be 0.3 mm or more and 2.0 mm or less.

[0057] The first joining process and the second joining process using the pressurizing device 110 will be described in turn below.

[0058] (First joining process)

[0059] like Figure 2 As shown, a laminate S is formed by laminating a second metal plate 41a made of aluminum or aluminum alloy on both sides of the ceramic substrate 10 using solder 50. The solder 50 can be an alloy such as Al-Si, Al-Ge, Al-Cu, Al-Mg, or Al-Mn.

[0060] Use such as Figure 4The pressurizing device 110 pressurizes the laminate S along the lamination direction, and the pressurizing device 110 is heated in a vacuum atmosphere, thereby bonding the second metal plate 41a to the ceramic substrate 10, thus forming the second metal layer 41 on both sides of the ceramic substrate 10. At this time, the surface of the laminate S is aluminum or aluminum alloy, so the metal foil 63 is made of aluminum foil or aluminum alloy foil, or stainless steel foil.

[0061] The pressure applied at this time is set to be above 0.1 MPa and below 3.4 MPa, the bonding temperature is set to be above 600°C and below 655°C, and the heating time is set to be above 15 minutes and below 120 minutes.

[0062] (Second joining process)

[0063] like Figure 3 As shown, a laminate S is formed by stacking a first metal plate 42a made of copper or a copper alloy on the second metal layer 41 formed on both sides of the ceramic substrate 10.

[0064] In use such Figure 4 While the pressurizing device 110 pressurizes the laminate S along the lamination direction, the pressurizing device 110 is heated in a vacuum atmosphere to solid-state diffusion bond the first metal plate 42a to the second metal layer 41, thereby forming the first metal layer 42 on the second metal layer 41. At this time, the surface of the laminate S is copper or a copper alloy, so the metal foil 63 is made of copper foil or a copper alloy foil, or stainless steel foil.

[0065] As stainless steel foil, SUS304 foil can be used, for example. Furthermore, titanium or nickel foil can also be used. In this case, titanium or nickel foil with a purity of 99% or higher is preferred.

[0066] The applied pressure is set to, for example, 0.3 MPa or more and 3.5 MPa or less, and the heating temperature is set to 400°C or more and less than 548°C. This pressurized and heated state is maintained for 5 minutes or more and 240 minutes or less, thereby solid-phase diffusion bonding between the second metal layer 41 and the first metal plate 42a, forming the first metal layer 42 on the second metal layer 41.

[0067] As described above, in the pressurizing device 110 of this embodiment, a metal foil 63 is disposed on the contact surface of the spacer 60 with the laminate S, with the spacer 60 positioned between the laminate S and the base plate 111 and between the laminate S and the pressing plate 114. The laminate S is a stacked state in which a first metal plate 42a is stacked on a second metal layer 41.

[0068] The metal foil 63 is a ductile material, so even when the surface of the laminate S is uneven or has a large flatness, the metal foil 63 deforms in a manner that follows the shape of the surface. Moreover, the product of the Young's modulus (GPa) and the thickness (mm) of the metal foil 63 is set to be 0.6 or more and 100 or less, thus exhibiting excellent deformation capability as described above.

[0069] Therefore, uniform pressure can be applied to the entire surface of the laminate S, and the entire surface can be uniformly bonded. Furthermore, since it is not a brittle material like carbon sheet, it will not break under pressure, and since it is a material that does not react with the first metal plate 42a provided on the surface of the laminate S, it will not adhere to the first metal plate 42a.

[0070] In summary, by using the pressurizing device 110 provided with the spacer 60, it is possible to manufacture a high-quality power module substrate (insulated circuit board) 1 without poor bonding.

[0071] This invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of this invention.

[0072] For example, the manufacturing method of the present invention can be applied to cases where a circuit layer consisting of a two-layer structure of an aluminum layer and a copper layer is formed on one side of a ceramic substrate, and as in the embodiment, a heat dissipation layer with no two-layer structure can also be formed on the other side of the ceramic substrate. In this case, the spacer in contact with the ceramic substrate 10 may not have metal foil 63.

[0073] In the above embodiments, the surface of the laminate is made of copper or a copper alloy, but it can also be made of aluminum or an aluminum alloy. In this case, it is preferable that the metal foil in the spacer is made of aluminum or an aluminum alloy, or stainless steel.

[0074] The manufacturing method of the present invention is applicable not only to the bonding of metal plates formed of copper or copper alloys to metal plates formed of aluminum or aluminum alloys, but also to the bonding of AlSiC composite materials to copper or copper alloys.

[0075] AlSiC composite material is an aluminum-silicon carbide composite formed by impregnating a metal with aluminum (Al: pure aluminum or aluminum alloy) as the main component in a porous body formed by silicon carbide (SiC), with an aluminum coating layer formed on the surface of the porous body.

[0076] When using this AlSiC composite material, such as Figure 8 As shown, a first metal plate 42a made of copper or copper alloy is stacked on each of the second metal layers 41 formed on both sides of the ceramic substrate 10, and a plate-shaped AlSiC composite material 70 is stacked on one of the first metal plates 42a to form a laminate.

[0077] With the metal foil (first metal foil) 63 in the spacer (first pressing member) 60 in contact with the surface of the AlSiC composite material 70, and the metal foil (second metal foil) 63 in the spacer (second pressing member) 60 in contact with the surface of the first metal plate 42a, and with the laminate being pressurized along the lamination direction, the laminate is heated in a vacuum atmosphere, thereby enabling the second metal layers 41 and the first metal plate 42a, and further enabling the first metal plate 42a and the AlSiC composite material 70 to be simultaneously bonded by solid-phase diffusion.

[0078] At this time, by using the method described in the above embodiments, a circuit layer and a heat dissipation layer formed by a first metal layer and a second metal layer are formed on a ceramic substrate, respectively, and an insulating circuit substrate in which the first metal layer of the heat dissipation layer is bonded to an AlSiC composite material as a heat sink can be manufactured.

[0079] That is, a second metal layer can be formed on both sides of a ceramic substrate (through a first bonding process), a first metal plate can be stacked on each of the second metal layers, and then an AlSiC composite material can be stacked on one of the first metal plates. The stacked bodies are then subjected to pressure and heating to achieve solid-phase diffusion bonding (second bonding process).

[0080] Furthermore, the present invention is not limited to the circuit layer and heat dissipation layer of the substrate for power modules, but can be applied to combinations of metals that can be bonded in both liquid and solid phases, and is particularly effective in combinations of metals that can be bonded in solid phase. Moreover, the present invention can also be applied to the bonding of metal plates to plate components other than metal plates (e.g., ceramic substrates).

[0081] Example

[0082] To confirm the effectiveness of the invention, an evaluation test was conducted. In this test, a second metal plate made of aluminum or an aluminum alloy and a first metal plate made of copper or a copper alloy were laminated and joined together. An aluminum alloy (A6063) was used as the second metal plate, and pure copper (C1020) was used as the first metal plate. The side of the metal plate in contact with the spacer was used as the bonding material.

[0083] The spacer is a laminated structure consisting of graphite sheets, carbon sheets, or ceramic sheets, and metal foil. The metal foil used is any one of the following: SUS304 as stainless steel (SUS), C1020 as copper (Cu), or A6063 as aluminum (Al). Their Young's modulus and thickness are shown in Table 1 (values ​​at room temperature (25°C)).

[0084] Laminates were also tested using spacers made from graphite sheets (PF-100 manufactured by Toyo Tanso Co., Ltd.), carbon sheets (G-347 manufactured by ASAHI-GRAPHITE Co., Ltd.), and ceramic sheets (Al2O3 ceramic sintered sheets manufactured by MARUWA CO.,LTD.).

[0085] The laminate of two metal plates was pressurized and heated at a pressure of 1.0 MPa, a temperature of 500 °C, and a holding time of 30 minutes. The tightness, adhesion (followability), and detachment of foreign matter from the surface of the spacer were evaluated.

[0086] (Evaluation of the tightness of the spacer)

[0087] Regarding the tightness of the spacer, after cooling to room temperature after bonding, the metal foil can be manually peeled off from the laminate. SEM observation of the cross-section of the metal foil and the laminate surface is performed. The case where no intermetallic compound is formed on the surface of the metal foil and the laminate is rated as "A", and the other cases are rated as "B".

[0088] (Evaluation of Adhesion)

[0089] Regarding the bonding performance, an ultrasonic flaw detector (FINESAT manufactured by Hitachi Power Solutions Co., Ltd.) was used to observe the interface between the two metal layers, measure the bonding area, and calculate the bonding rate based on the area to be bonded (the area of ​​the metal layers) before bonding. A bonding rate of 95% or higher was designated as "A", and a bonding rate of less than 95% was designated as "B".

[0090] (Evaluation of threshing on the surface)

[0091] After bonding, the spacer is peeled off from the bonded material. When the surface of the bonded material after micro-etching of 2-3 μm is observed by SEM-EDX, the case where no carbon or ceramic components are attached to the pressure surface is designated as "A", and the case where a part of the metal foil remains on the bonded material is designated as "B".

[0092] For micro-etching, if the substrate is Al, use a sodium hydroxide aqueous solution (5% by mass) at 50°C for 2 minutes. If the substrate is Cu, use CL-8 (20% by volume) manufactured by ADEKA CORPORATION at room temperature (25°C) for 2 minutes.

[0093] [Table 1]

[0094]

[0095] [Table 2]

[0096]

[0097] As shown in Tables 1 and 2, when a metal foil that does not react with the substrate is used on the surface of the spacer, samples No. 8 to 20, in which the product of the Young's modulus and thickness of the metal foil is 0.6 or higher and 100 or lower, show no adhesion to the substrate. Specifically, according to Figure 6 The SEM image of sample No. 8 shows that no foreign matter adheres to the surface of the bonded material. However, in sample No. 1, according to... Figure 7 The SEM image shown indicates that foreign matter is attached to the surface of the material being bonded.

[0098] In samples No. 4 and No. 6, the product of Young's modulus and thickness of the metal foil was too large, resulting in poor bonding. In samples No. 3 and No. 5, the product of Young's modulus and thickness of the metal foil was too small, causing the metal foil to crack, and foreign matter was observed at the site.

[0099] In sample No. 7, intermetallic compounds were confirmed by SEM observation of the Cu / Al cross-section, and poor adhesion between the spacer and the bonded material was observed.

[0100] Industrial availability

[0101] When multiple different plate components are joined by applying pressure under heating, a uniform pressure can be applied to the laminate to create a good joint, and foreign matter can be prevented from adhering to the surface of the laminate.

[0102] Symbol Explanation

[0103] 1. Power module substrate (joint) (insulating circuit board)

[0104] 10. Ceramic substrate (second plate component)

[0105] 20 Circuit Layers

[0106] 30 heat dissipation layer

[0107] 41 Second metal layer (second plate component)

[0108] 41a Second metal plate (first plate component / second plate component)

[0109] 42 First metal layer

[0110] 42a First metal plate (first plate component)

[0111] 50 Brazing filler metal

[0112] 60 Spacer plates (first pressing component and second pressing component)

[0113] 61 Graphite sheets

[0114] 62 carbon sheet

[0115] 63 Metal foil (first metal foil and second metal foil)

[0116] 70 AlSiC composite material

[0117] 110 Pressurization device.

Claims

1. A method of manufacturing a bonded body, characterized by, An interface body is manufactured by solid phase diffusion bonding a first plate member to a second plate member by pressing and heating a laminate of the first plate member and the second plate member, the first plate member includes a first metal plate, a first pressing member in which three layers of a first metal foil, a carbon sheet, and a graphite sheet or three layers of a first metal foil, a ceramic sheet, and a graphite sheet are sequentially stacked is disposed with the first metal foil in contact with a surface of the first plate member, the first metal foil is formed of a material that does not react with the first plate member at a contact surface of the first metal foil when heated, a product of a Young's modulus of the first metal foil and a thickness of the first metal foil is 0.6 or more and 100 or less, the Young's modulus being in GPa, and the thickness being in mm.

2. The method of manufacturing an interface body according to claim 1, wherein a second pressing member in which three layers of a second metal foil, a carbon sheet, and a graphite sheet or three layers of a second metal foil, a ceramic sheet, and a graphite sheet are sequentially stacked is disposed with the second metal foil in contact with a surface of the second plate member, the second metal foil is formed of a material that does not react with the second plate member at a contact surface of the second metal foil when heated, a product of a Young's modulus of the second metal foil and a thickness of the second metal foil is 0.6 or more and 100 or less, the Young's modulus being in GPa, and the thickness being in mm.

3. The method of manufacturing an interface body according to claim 1 or 2, wherein one of the first plate member or the second plate member is formed of copper or a copper alloy, and the other is formed of aluminum or an aluminum alloy.

4. A method for manufacturing an insulating circuit substrate, characterized by the method of manufacturing an interface body according to any one of claims 1 to 3, the first plate member is formed of a first metal plate formed of copper or a copper alloy, the second plate member is formed of a ceramic substrate and a second metal plate joined to one face of the ceramic substrate and formed of aluminum or an aluminum alloy, the laminate is formed by stacking the first metal plate on the second metal plate joined to the ceramic substrate, and the first metal plate and the second metal plate are solid phase diffusion bonded with the first metal foil in contact with the first metal plate.

5. A method for manufacturing an insulating circuit substrate, characterized by the method of manufacturing an interface body according to claim 2, the first plate member is formed by stacking a first metal plate formed of copper or a copper alloy and an AlSiC composite material formed by impregnating a porous body of silicon carbide with a metal having aluminum as a main component, the second plate member is formed of a ceramic substrate, a second metal plate joined to both faces of the ceramic substrate and formed of aluminum or an aluminum alloy, and the first metal plate stacked on the second metal plate of one face, the laminate is formed by stacking the first plate member and the second plate member with the second metal plate of the other face of the second plate member in contact with the first metal plate of the first plate member, the laminate is formed by stacking the first plate member and the second plate member with the second metal plate of the other face of the second plate member in contact with the first metal plate of the first plate member, In a state where the first metal foil of the first pressing member is brought into contact with the AlSiC composite material and the second metal foil of the second pressing member is brought into contact with the surface of the first metal plate of the second plate member, the first metal plate and the second metal plate and the first metal plate and the AlSiC composite material are simultaneously subjected to solid-phase diffusion bonding.

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