Method for manufacturing joined body and method for manufacturing insulating circuit board

Abstract

To uniformly pressurize a laminate of different plate members and producing an excellent joint body when joining them in a pressurized and heated state, and prevent foreign matter from depositing on the surface of the laminate.SOLUTION: The present invention provides a method for producing a joint body by pressurizing and heating a laminate, which comprises a first plate member and a second plate member, with a spacer brought into contact with the surface of the first plate member. The first plate member is a metal plate. In the spacer, at least a contact part with the first plate member is composed of a metal plate not to react with the first plate member during heating. The contact part is provided with a coat composed of a metal compound comprising at least one of oxide, nitride, and carbide. The metal plate of the spacer has a thickness of 0.2 mm or more and 1.0 mm or less. The coat composed of the metal compound has a thickness of 30 nm or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a bonded body consisting of a plurality of different plate members, such as a substrate for a power module, and in particular to a manufacturing method suitable for bonding metal plates together by solid-state diffusion bonding, and a manufacturing method for an insulating circuit board using the manufacturing method for the bonded body. [Background technology]

[0002] A power module substrate (insulating circuit substrate) generally has a structure in which a circuit layer is formed on one surface of a ceramic substrate that serves as an insulating layer, and a heat dissipation layer for heat dissipation is formed on the other surface.

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

[0004] In this power module substrate, the ceramic substrate and the metal plate are bonded by applying pressure and heat to the laminate using a pressure device. At this time, a spacer made of a carbon layer and a graphite layer is interposed between the laminate and the pressure device. In this case, the carbon layer is disposed on the laminate side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-63145 A Summary of the Invention [Problem to be solved by the invention]

[0006] In some cases, the circuit layer of this type of power module substrate has a two-layer structure of aluminum and copper. To manufacture such a joint consisting of multiple different metal plates, a copper plate is joined to an aluminum layer formed on a ceramic substrate by the method described in Patent Document 1 to form a copper layer, but the joining of aluminum and copper may be performed by solid-phase diffusion bonding, which involves applying pressure and heat without using a brazing material.

[0007] In this case, it is necessary to apply pressure more uniformly than in the case of joining via a brazing material, but in the pressure application device described in Patent Document 1, the side of the spacer that comes into contact with the laminate is formed from a carbon layer, so displacement due to the application of load when applying pressure is small. If there are minute irregularities on the surface of the laminate or if the flatness is high, these cannot be absorbed and the pressure is not applied uniformly, which may result in poor joining.

[0008] Furthermore, if the surface of the spacer that contacts the laminate is formed of a carbon layer, this carbon layer may locally fall off when it is heated and pressurized together with the laminate, and part of the carbon layer may adhere to the surface of the laminate. Even if a soft etching process is performed on the surface of the bonded body to remove this foreign matter, it is not possible to completely remove it, resulting in a problem that semiconductor elements and the like cannot be mounted on the laminate (circuit layer) after bonding.

[0009] On the other hand, if a strong etching process is performed to remove foreign matter, the surface of the laminate after bonding becomes rough, so in this case too, it is not possible to mount a semiconductor element or the like on the circuit layer.

[0010] The present invention has been made in consideration of the above circumstances, and aims to produce a good joined body by uniformly pressurizing the laminate of multiple different plate members when the laminate is joined under pressure and heat, while suppressing the adhesion of foreign matter to the surface of the laminate. [Means for solving the problem]

[0011] The method for manufacturing a joined body of the present invention is a method for manufacturing a joined body, which comprises pressurizing and heating a laminate of a first plate member and a second plate member while a spacer is in contact with the surface of the first plate member to produce a joined body, wherein the first plate member is a metal plate, the spacer is made of a metal plate that does not react with the first plate member when heated, at least at the contact portion with the first plate member, and has a coating made of a metal compound including at least one of an oxide, a nitride and a carbide formed on its surface, the metal plate of the spacer has a thickness of 0.2 mm or more and 1.0 mm or less, and the coating made of the metal compound has a thickness of 30 nm or more.

[0012] Since the contact portion of the spacer with the first plate member is made of a metal plate that does not react with the surface of the first plate member when heated, when the laminate is pressurized and heated through this spacer, the contact portion of the spacer can be prevented from adhering to the surface of the first plate member of the laminate.

[0013] In addition, when a metal plate having a thermal expansion coefficient different from that of the first plate member of the laminate is used as the metal plate constituting the contact portion of the spacer, when the spacer and the laminate are pressurized, the contact portion and the first plate member are in a pressure-bonded state, and due to the difference in thermal expansion coefficients, stress along the surface direction is generated between the spacer and the first plate member during heating and cooling, and this stress may destroy the bonding interface between the first member and the second plate member during thermal expansion and contraction (cooling) of the laminate (bonded body). In this regard, by forming a coating made of the above-mentioned metal compound on the contact portion, it is possible to suppress the spacer and the first plate member from being in a pressure-bonded state, and to bond the first plate member and the second plate member well.

[0014] If the thickness of the metal plate of the spacer is less than 0.2 mm, it will deform under pressure and become impossible to reuse. If the thickness of the metal plate exceeds 1.0 mm, poor bonding will occur. For this reason, the thickness of the metal plate is preferably 0.2 mm or more and 1.0 mm or less. If the thickness of the coating made of the metal compound is less than 30 nm, it will be pressed against the laminate, so the thickness of the coating is preferably 30 nm or more.

[0015] In the method for producing a joint of the present invention, it is preferable that the metal plates constituting the contact portions are heat-treated. The coating can be formed efficiently by heat treating the metal plate.

[0016] In the present invention, either the first plate member or the second plate member may be made of copper or a copper alloy, and the other may be made of aluminum or an aluminum alloy.

[0017] Aluminum and copper are generally bonded by solid-phase diffusion bonding, and the present invention is particularly effective in such solid-phase bonding. However, liquid-phase bonding using a brazing material is not excluded. For example, the present invention can also be applied to a case where the first plate member is made of a metal plate, the second plate member is made of a ceramic substrate, and they are bonded together using a brazing material. Effect of the Invention

[0018] According to the method for manufacturing a bonded body of the present invention, when a stack of multiple different plate members is pressurized and bonded in a heated state, a uniform pressure is applied to the stack to produce a good bonded body and the adhesion of foreign matter to the surface of the stack can be suppressed.

[0019] The method for manufacturing an insulated circuit board of the present invention is a method for manufacturing an insulated circuit board using the above-mentioned method for manufacturing a bonded body, wherein the first plate member is made of a first metal plate made of copper or a copper alloy, the second plate member is made of a ceramic substrate and a second metal plate made of aluminum or an aluminum alloy bonded to one side of the ceramic substrate, the first metal plate is laminated on the second metal plate bonded to the ceramic substrate to form the laminate, and the first metal plate and the second metal plate are solid-state diffusion bonded together with the stainless steel plate in contact with the first metal plate.

[0020] Another method for producing an insulating circuit board is a method for producing an insulating circuit board using the above-mentioned method for producing a bonded body, in which two sets of the spacers are used, the first plate member is formed by laminating a first metal plate made of copper or a copper alloy and an AlSiC composite material obtained by impregnating a porous body of silicon carbide with a metal mainly composed of aluminum, the second plate member is formed by a ceramic substrate, a second metal plate made of aluminum or an aluminum alloy bonded to both sides of the ceramic substrate, and the first metal plate laminated on one of the second metal plates, the other second metal plate of the second plate member is brought into contact with the first metal plate of the first plate member to laminate the first plate member and the second plate member to form the laminate, and the stainless steel plate of one of the spacers is brought into contact with the AlSiC composite material, and the stainless steel plate of the other spacer is brought into contact with the surface of the first metal plate of the second plate member, and the first metal plate and the second metal plate, and the first metal plate and the AlSiC composite are simultaneously solid-phase diffusion bonded to each other. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view showing a power module substrate as an embodiment of a bonded body (insulating circuit board) of the present invention. [Diagram 2] 2 is a cross-sectional view showing a state before a metal plate is bonded to a ceramic substrate of the power module substrate in FIG. 1. [Diagram 3] 3 is a cross-sectional view showing a state before a second metal plate is bonded to the metal layer after bonding in FIG. 2. FIG. [Figure 4] FIG. 4 is a front view of a pressure device used in joining the structures shown in FIGS. 2 and 3. [Diagram 5] FIG. 5 is a cross-sectional view of a spacer used in the pressure device of FIG. [Figure 6] FIG. 11 is a cross-sectional view showing a state before bonding in the case of manufacturing another power module substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment is a power module substrate 1 as an example of an insulating circuit substrate (joint). As shown in Fig. 1, this power module substrate 1 includes a ceramic substrate 10, a circuit layer 20 bonded to one surface of the ceramic substrate 10, and a heat dissipation layer 30 bonded to the other surface of the ceramic substrate 10.

[0023] For example, nitride ceramics such as AlN (aluminum nitride) and Si3N4 (silicon nitride) or oxide ceramics such as Al2O3 (alumina) can be used for the ceramic substrate 10. The thickness of the ceramic substrate 10 is set to 0.2 mm or more and 1.5 mm or less.

[0024] The circuit layer 20 and the heat dissipation layer 30 each have a two-layer structure made of a second metal layer 41 made of aluminum or an aluminum alloy and a first metal layer 42 made of copper or a copper alloy. In other words, in the power module substrate 1, the second metal layer 41 is formed on both sides of the ceramic substrate 10, and the first metal layer 42 is formed on the second metal layer 41.

[0025] The second metal layer 41 can be made of pure aluminum having a purity of 99% by mass or more (for example, pure aluminum in the 1000 series according to the JIS standard, particularly 1N90 (purity of 99.9% by mass or more: so-called 3N aluminum) or 1N99 (purity of 99.99% by mass or more: so-called 4N aluminum), or an aluminum alloy such as an A6063 series. In order to buffer the difference in thermal expansion and contraction between the first metal layer 42 and the ceramic substrate 10, it is preferable to use pure aluminum for the second metal layer 41.

[0026] The first metal layer 42 is preferably made of, for example, copper with a purity of 99.96% by mass or more (oxygen-free copper) or copper with a purity of 99.90% by mass or more (tough pitch copper).

[0027] The thicknesses of the second metal layer 41 and the first metal layer 42 are not limited, but for example, the second metal layer 41 is 0.1 mm or more and 2.0 mm or less, and the first metal layer 42 is 0.2 mm or more and 5.0 mm or less. The second metal layer 41 and the first metal layer 42 may have the same thickness in the circuit layer 20 and the heat dissipation layer 30, or may have different thicknesses. In the illustrated example, the second metal layer 41 and the first metal layer 42 are denoted by the same reference numerals without distinguishing between the circuit layer 20 and the heat dissipation layer 30.

[0028] A method for manufacturing the power module substrate 1 thus configured will be described.

[0029] First, as shown in FIG. 2, a second metal plate 41a made of aluminum or an aluminum alloy is laminated on both sides of a ceramic substrate 10 via a brazing material 50, and the laminate is pressurized and heated to bond the ceramic substrate 10 and the second metal plate 41a, thereby forming a second metal layer 41 on both sides of the ceramic substrate 10 (first bonding process).

[0030] Next, as shown in FIG. 3, a first metal plate 42a made of copper or a copper alloy is laminated on the second metal layer 41, and the laminate is pressurized and heated to perform solid-state diffusion bonding between the aluminum and copper, thereby forming a first metal layer 42 on the second metal layer 41 (second bonding process).

[0031] The present invention is applied to both of these joining processes. In the first bonding step, the second metal plate 41a corresponds to the first plate member of the present invention, and the ceramic substrate 10 corresponds to the second plate member of the present invention. Meanwhile, in the second bonding step, the first metal plate 42a corresponds to the first plate member of the present invention, and the ceramic substrate 10 and the second metal plate 41a (second metal layer 41) bonded to one surface of the ceramic substrate 10 correspond to the second plate member of the present invention.

[0032] In this manufacturing method, a pressure device 110 shown in Fig. 4 is used to pressurize the laminate in the first bonding step and the laminate in the second bonding step. In the following, the laminate in the first bonding step (a laminate made of the ceramic substrate 10 and both second metal plates 41a) and the laminate in the second bonding step (a laminate made of the ceramic substrate 10 on which both second metal layers 41 are formed and the first metal plate 42a) will be described as the laminate S without distinction.

[0033] The pressure applying device 110 comprises a base plate 111, guide posts 112 attached vertically to the four corners of the upper surface of the base plate 111, a fixed plate 113 fixed to the upper ends of the guide posts 112, a pressure plate 114 supported by the guide posts 112 so as to be freely movable up and down between the base plate 111 and the fixed plate 113, and a biasing portion 115 such as a spring provided between the fixed plate 113 and the pressure plate 114 to bias the pressure plate 114 downward.

[0034] The fixed plate 113 and the pressure plate 114 are disposed parallel to the base plate 111, and the laminate S is disposed between the base plate 111 and the pressure plate 114. On the sides of the base plate 111 and the pressing plate 114 that come into contact with the laminate S, a spacer 60 is disposed to ensure uniform pressure.

[0035] As shown in FIG. 5, each spacer 60 has a structure in which a graphite sheet 61 and a metal plate 62 are laminated together. Graphite sheet 61 is made of a soft graphite material having cushioning properties, and is constructed by laminating multiple thin flake graphite films like mica. It is made by treating natural graphite with acid, forming it into a sheet, and rolling it. This graphite sheet 61 has a bulk density of 0.5 Mg / m 3 More than 1.3Mg / m 3 For example, Asahi Graphite Co., Ltd.'s T-5 (thermal conductivity: 75.4 W / mK, elastic modulus: 11.4 GPa) and Toyo Tanso Co., Ltd.'s graphite sheet PF (compressibility 47%, recovery rate 14%) can be used.

[0036] The metal plate 62 is made of a material that does not react with the surface of the laminate S when heated. The non-reactive material refers to a material that does not peel off when cooled from the joining temperature to room temperature and does not form an intermetallic compound between the metal plate and the surface of the laminate.

[0037] For example, when the second metal plates 41a arranged on both sides of the laminate S in the first bonding step are made of aluminum or an aluminum alloy, it is preferable that the metal plate 62 of the spacer 60 is made of aluminum, an aluminum alloy, or stainless steel, and when the first metal plates 42a arranged on both sides of the laminate S in the second bonding step are made of copper or a copper alloy, it is preferable that the metal plate 62 is made of copper, a copper alloy, or stainless steel. As the stainless steel, for example, SUS304 can be used. Titanium or nickel can also be used. In this case, it is preferable to use titanium or nickel with a purity of 99% or more.

[0038] A coating 63 made of a metal compound containing at least one of an oxide, nitride, and carbide of the elements constituting the metal plate 62 is formed on the surface of the metal plate 62. In order to form this coating 63, the metal plate 62 is subjected to a heat treatment in advance. For example, a metal plate made of stainless steel (e.g., SUS304) is heated to 500°C in air for 60 minutes to form a coating 63 made of an oxide (iron oxide) having a thickness of about 60 nm in SiO2 equivalent. This thickness was determined by XPS analysis (using a VersaProbe II manufactured by ULVAC-PHI, Inc., with a sputtering rate of 2.35 nm / min (SiO2 equivalent)). The coating 63 was formed in a vacuum atmosphere (e.g., 10 -2 The heat treatment may be performed in a vacuum atmosphere (pressure of 10 Pa or less) or in a nitrogen gas atmosphere. The thickness of the coating 63 formed by this heat treatment is preferably 30 nm or more, and more preferably 350 nm or less.

[0039] There is no particular limitation on the overall thickness of spacer 60. Graphite sheet 61 may have a thickness of 0.5 mm or more and 5.0 mm or less. Metal plate 62 may have a thickness of 0.2 mm or more and 1.0 mm or less.

[0040] Hereinafter, the first bonding step and the second bonding step using this pressure device 110 will be described in order.

[0041] (First joining process) 2, a second metal plate 41a made of aluminum or an aluminum alloy is laminated on both sides of a ceramic substrate 10 via a brazing material 50 to form a laminate S. As the brazing material 50, an alloy such as an Al-Si based, Al-Ge based, Al-Cu based, Al-Mg based, or Al-Mn based alloy is used.

[0042] The laminate S is pressed in the stacking direction using a pressurizing device 110 shown in Fig. 4, and heated together with the pressurizing device 110 in a vacuum atmosphere, thereby bonding the second metal plate 41a to the ceramic substrate 10 and forming the second metal layer 41 on both sides of the ceramic substrate 10. At this time, the spacer is arranged so that the metal plate contacts the second metal plate. In addition, since the surface of the laminate S is aluminum or an aluminum alloy, aluminum or an aluminum alloy, or stainless steel is used for the metal plate 62.

[0043] The pressure at this time is, for example, 0.1 MPa to 3.4 MPa, the joining temperature is 600° C. to 655° C., and the heating time is 15 minutes to 120 minutes.

[0044] (Second joining process) As shown in FIG. 3, a laminate S is formed by laminating a first metal plate 42a made of copper or a copper alloy on each of second metal layers 41 formed on both sides of a ceramic substrate 10.

[0045] 4, the laminate S is pressed in the stacking direction, and 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. In this case, since the surface of the laminate S is copper or a copper alloy, copper or a copper alloy, or stainless steel is used for the metal plate 62.

[0046] In this case, the pressure is, for example, from 0.3 MPa to 3.5 MPa, and the heating temperature is from 400° C. to less than 548° C. By maintaining this pressurized and heated state for 5 minutes to 240 minutes, the second metal layer 41 and the first metal plate 42a are solid-phase diffusion bonded together, and the first metal layer 42 is formed on the second metal layer 41.

[0047] As described above, in the pressure application device 110 of this embodiment, a spacer 60 is interposed between the laminate S, in which a first metal plate 42a is laminated on a second metal layer 41, and the base plate 111 and the pressing plate 114, and a metal plate 62 is disposed on the contact surface side of the spacer 60 with the laminate S.

[0048] Since the metal plate 62 is a ductile material, even if the surface of the laminate S is uneven or has low flatness, the metal plate 62 deforms to follow the shape of the surface. Therefore, a uniform pressure can be applied to the entire surface of the laminate S, and the entire surface can be evenly bonded. In addition, since the metal plate 62 is not a brittle material like a carbon sheet, it will not be damaged by pressure, and since the material 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.

[0049] Furthermore, since the coating 63 made of a metal compound is formed on the metal plate 62 of the spacer 60, pressure bonding between the metal plate 62 of the spacer 60 and the metal plates 41a, 42a of the laminate S is suppressed during bonding. That is, the metal plate 62 constituting the contact portion of the spacer 60 and the metal plates 41a, 42a of the laminate S have different thermal expansion coefficients. For this reason, if there is no coating 63 and the surface of the metal plate 62 is exposed, when heated while being pressurized by the pressurizing device 110, the metal plate 62 of the spacer 60 and the metal plates 41a, 42a of the laminate S will be in a pressure-bonded state, and due to the difference in thermal expansion coefficients, stress will be generated along the surface between the metal plate 62 of the spacer 60 and the metal plates 41a, 42a of the laminate S during heating and cooling. This stress may destroy the bonding interface with the ceramic substrate 10 or the second metal layer 41 to be bonded.

[0050] In this regard, by forming a coating 63 made of a metal compound on the metal plate 62 of the spacer 60, it is possible to prevent the metal plate 62 and the metal plates 41a, 42a of the laminate S from coming into a pressure-bonded state, thereby achieving good bonding. If the metal plate of spacer 60 is thin like a foil, it will deform when metal plates 41a, 42a of laminate S thermally expand and contract, thereby suppressing destruction of the bonding interface with ceramic substrate 10 and second metal layer 41 to be bonded, but since metal plate 62 has a predetermined thickness (0.2 mm or more), it is difficult to follow the thermal expansion and contraction of metal plates 41a, 42a of laminate S, so it is particularly effective to be able to avoid the pressure-bonded state by coating 63. However, if metal plate 62 is too thick, there is a risk that graphite sheet 61 will be crushed, so it is preferable that the thickness is 1.0 mm or less.

[0051] As described above, by using the pressure device 110 provided with the spacer 60, a high-quality power module substrate (insulating circuit substrate) 1 without bonding defects can be manufactured.

[0052] The present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0053] For example, the manufacturing method of the present invention can be applied to the case where a circuit layer having a two-layer structure of an aluminum layer and a copper layer is formed on one surface of a ceramic substrate, and the other surface of the ceramic substrate does not need to have a two-layer heat dissipation layer as in the embodiment. In this case, the spacer in contact with the ceramic substrate 10 does not need to include the metal plate 62.

[0054] The manufacturing method of the present invention may be applied not only to joining a metal plate made of copper or a copper alloy to a metal plate made of aluminum or an aluminum alloy, but also to joining an AlSiC composite material to copper or a copper alloy.

[0055] AlSiC composites are composites of aluminum and silicon carbide formed by impregnating a porous body made of silicon carbide (SiC) with a metal whose main component is aluminum (Al: pure aluminum or aluminum alloy), and an aluminum coating layer is formed on the surface of the porous body.

[0056] When using this AlSiC composite, as shown in Figure 6, a first metal plate 42a made of copper or a copper alloy is laminated on each second metal layer 41 formed on both sides of a ceramic substrate 10, and a plate-shaped AlSiC composite 70 is laminated on one of the first metal plates 42a to form a laminate.

[0057] By heating this laminate in a vacuum atmosphere while contacting the metal plate 62 of the spacer 60 with the surface of the AlSiC composite 70 and the metal plate 62 of the spacer 60 with the surface of the first metal plate 42a and pressurizing the laminate in the stacking direction, each second metal layer 41 and the first metal plate 42a, and further the first metal plate 42a and the AlSiC composite 70 can be simultaneously solid-state diffusion bonded.

[0058] In this case, a circuit layer and a heat dissipation layer each consisting of a first metal layer and a second metal layer are formed on a ceramic substrate by the method described in the above embodiment, and an AlSiC composite material is bonded to the first metal layer of the heat dissipation layer as a heat sink to produce an insulated circuit substrate.

[0059] That is, second metal layers are formed on both sides of a ceramic substrate (by a first bonding process), each first metal plate is laminated onto each second metal layer, and an AlSiC composite is laminated onto one of the first metal plates, and the laminate is pressurized and heated to perform solid-state diffusion bonding (second bonding process).

[0060] In addition, the present invention is not limited to the circuit layer and heat dissipation layer of the power module substrate, but can be applied to combinations of metals that can be bonded in liquid and solid phases, and is particularly effective for combinations of metals that can be bonded in solid phase. The present invention can also be applied to bonding between a metal plate and a plate member other than a metal plate (for example, a ceramic substrate). EXAMPLES

[0061] An evaluation test was carried out to confirm the effect of the present invention. In this test, a metal plate made of an aluminum alloy (A6063) and a metal plate made of pure copper (C1020) were laminated and joined. The metal plate on the side in contact with the spacer was used as the adherend.

[0062] The spacer was a laminated structure consisting of a graphite sheet (PF-100 manufactured by Toyo Tanso Co., Ltd.) and a metal plate as the contact part. The metal plate was made of either stainless steel (SUS304), copper (C1020), aluminum (A6063), nickel (Ni), or titanium (Ti). In addition, as conventional examples, spacers using carbon, graphite, or ceramics in the contact part were also tested. The thickness of the spacer contact part was as shown in Table 1.

[0063] The laminate of both 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 to check for the presence or absence of metal compounds on the surface of the spacer metal plate, and to evaluate the deformation, adhesion, and bonding (followability) of the spacer metal plate.

[0064] (Confirmation of metal compounds) Using XPS analysis (VersaProbe II, manufactured by ULVAC-PHI, Inc.), the sputtering rate was calculated from 2.35 nm / min (SiO2 equivalent) for the time until the metal ratio of the spacer base material exceeded 85 at% from the outermost surface by sputtering. This sputtering rate was calculated from the time required to etch a 20 nm thick SiO2 film by sputtering in a rectangular area of ​​2.8 × 3.5 mm to a thickness of 1 nm. Using this sputtering rate, the metal compounds were confirmed from the time required to measure the metal compounds.

[0065] (Evaluation of spacer deformation) After joining, the spacer was peeled off from the adherend. If the spacer was cracked or deformed (such as being bent at the edge of the adherend, making it impossible to reuse), it was rated as "B." If no such cracks or deformation occurred, it was rated as "A."

[0066] (Evaluation of spacer adhesion) Regarding the adhesion of the spacer, after joining, it was cooled to room temperature, and the metal plate could be manually peeled off from the laminate. Furthermore, the cross sections of the metal plate and the laminate surface were observed under an SEM. If no intermetallic compound was formed between the metal plate and the laminate surface, it was rated as "A", and all other cases were rated as "B".

[0067] (Evaluation of Jointness) Bonding was evaluated using an ultrasonic flaw detector (FINESAT manufactured by Hitachi Power Solutions) to observe the interface between the two metal layers and measure the area to be bonded. The bonding rate was calculated from the area to be bonded (area of ​​the metal layers) before bonding. A bonding rate of 95% or more was given an "A" rating, and a rate of less than 95% was given a "B". The results are shown in Table 1. In all cases, an "A" is considered a pass.

[0068] [Table 1]

[0069] As shown in Table 1, in the examples in which a metal plate that does not react with the adherend is used at the contact portion of the spacer, the thickness of which is 0.2 mm to 1.0 mm, and a layer of a metal compound of 30 nm or more is formed on the surface, no intermetallic compound is observed between the metal plate of the spacer and the adherend, and there is no deformation or pressure bonding with the adherend. In addition, the bonding property was also good. In Example 12, the thickness of the metal compound is as thick as 350 nm, and strict condition control is required to prevent it from falling off. For this reason, the thickness of the metal compound film is preferably 300 nm or less. In contrast, in Comparative Example 1, the thickness of the metal compound on the spacer surface was as small as 20 nm, and therefore adhesion between the spacer and the adherend was observed. In Comparative Examples 2 and 4, the thickness of the metal plate of the spacer was too thin at 0.15 mm, and therefore deformation occurred, making it impossible to reuse. In Comparative Example 3, the thickness of the metal plate of the spacer was too thick at 1.2 mm, and therefore poor bonding occurred. In Comparative Examples 5 and 6, the metal plate of the laminate and the metal plate of the spacer were a combination of copper and aluminum, and therefore reacted and bonded together. In the conventional examples in which carbon, graphite, or ceramics was used instead of a metal plate for the spacer, defects occurred in either the deformation of the spacer, the bonding between the spacer and the laminate, or the bonding properties. [Explanation of symbols]

[0070] 1 Power module substrate (joint) (insulated circuit board) 10 Ceramic substrate (second plate member) 20 circuit layers 30 Heat dissipation layer 41 Second metal layer (second plate member) 41a Second metal plate (first plate member / second plate member) 42 First metal layer 42a First metal plate (first plate member) 50 Brazing material 60 Spacer 61 Graphite Sheet 62 Metal plate 63 Coating 70 AlSiC composite 110 Pressurizing device

Claims

1. A method for manufacturing a joined body, comprising the steps of: pressing and heating a laminate of a first plate member and a second plate member with a spacer in contact with a surface of the first plate member, the laminate producing a joined body, the method being characterized in that the first plate member is a metal plate; the spacer is made of a metal plate that does not react with the first plate member when heated, at least at a portion in contact with the first plate member, and a coating made of a metal compound including at least any one of an oxide, a nitride and a carbide is formed on the contact portion; the metal plate of the spacer has a thickness of 0.2 mm or more and 1.0 mm or less; and the coating made of the metal compound has a thickness of 30 nm or more.

2. 2. The method for manufacturing a joint according to claim 1, wherein the metal plates constituting the contact portions are heat-treated.

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

4. A method for producing an insulating circuit board using the method for producing a bonded body according to any one of claims 1 to 3, comprising the steps of: The first plate member is a first metal plate made of copper or a copper alloy, The spacer has a contact portion made of a stainless steel plate, the second plate member includes a ceramic substrate and a second metal plate made of aluminum or an aluminum alloy bonded to one surface of the ceramic substrate; a first metal plate is laminated on the second metal plate bonded to the ceramic substrate to form the laminate, and the first metal plate and the second metal plate are solid-state diffusion bonded together while the stainless steel plate is in contact with the first metal plate.

5. A method for producing an insulating circuit board using the method for producing a bonded body according to any one of claims 1 to 3, comprising the steps of: Two sets of the spacer are used, At least a contact portion of each of the spacers with the first plate member and a contact portion of each of the spacers with the second plate member are made of stainless steel plate, The first plate member is a first metal plate made of copper or a copper alloy, and a porous silicon carbide body with an aluminum and an AlSiC composite material impregnated with a metal mainly composed of aluminum, The second plate member includes a ceramic substrate, a second metal plate made of aluminum or an aluminum alloy bonded to both sides of the ceramic substrate, and the first metal plate laminated on one of the second metal plates, the other second metal plate of the second plate member is brought into contact with the first metal plate of the first plate member, thereby stacking the first plate member and the second plate member to form the laminate; A method for manufacturing an insulated circuit board, characterized in that the stainless steel plate of one of the spacers is brought into contact with the AlSiC composite material and the stainless steel plate of the other spacer is brought into contact with a surface of the first metal plate of the second plate member, and then the first metal plate and the second metal plate, and the first metal plate and the AlSiC composite material are simultaneously solid-state diffusion bonded.

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