Method for manufacturing copper / ceramic assembly, and method for manufacturing insulated circuit board

Abstract

To provide a method for manufacturing a copper / ceramic assembly capable of manufacturing a copper / ceramic assembly which can suppress generation of solder stains on the surface of a copper plate and is excellent in joint reliability.SOLUTION: A method for manufacturing a copper / ceramic assembly includes a joint material arrangement step of arranging a joint material between a copper member and a ceramic member, a lamination step of laminating the copper member and the ceramic member through the joint material, and a joint step of heating the copper member and the ceramic member laminated through the joint material under vacuum atmosphere, in a state in which the members are pressurized in a lamination direction, and joining the members, wherein the joint material contains Ag powder having oxygen concentration of less than 0.3 mass%, active metal powder and an organic compound containing O and N in the structure, the organic compound is an organic compound having a thermal decomposition temperature (temperature at which weight reduction rate by TG-DTA is 95% or less) of higher than 300°C, and a content of the organic compound in the joint material is within the range of 3 mass% or more and 10 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a copper / ceramic bonded body formed by bonding a copper member made of copper or a copper alloy to a ceramic member, and a method for producing an insulated circuit board formed by bonding a copper or copper alloy plate to a ceramic substrate. [Background technology]

[0002] In power modules, LED modules, and thermoelectric modules, a power semiconductor element, an LED element, and a thermoelectric element are bonded to an insulating circuit board having a circuit layer made of a conductive material formed on one side of an insulating layer. For example, power semiconductor elements for controlling large amounts of power, which are used to control wind power generation, electric vehicles, hybrid vehicles, etc., generate a large amount of heat during operation, and therefore, as a substrate for mounting these elements, an insulated circuit board has been widely used, which includes a ceramic substrate and a circuit layer formed by bonding a metal plate with excellent conductivity to one surface of the ceramic substrate. Note that an insulated circuit board in which a metal layer is formed by bonding a metal plate to the other surface of the ceramic substrate is also provided.

[0003] For example, Patent Document 1 proposes a ceramic circuit board in which the first and second metal plates constituting the circuit layer and metal layer are copper plates, and the copper plates are directly bonded to a ceramic substrate by the DBC method. In this DBC method, a eutectic reaction between copper and copper oxide is utilized to generate a liquid phase at the interface between the copper plate and the ceramic substrate, thereby bonding the copper plate and the ceramic substrate.

[0004] Furthermore, Patent Documents 2 and 3 propose a power module substrate in which a circuit layer and a metal layer are formed by bonding copper plates to one surface and the other surface of a ceramic substrate. In Patent Document 2, a ceramic substrate and a copper plate are joined together using an Ag-Cu-Ti brazing filler metal. In Patent Document 3, a ceramic substrate and a copper plate are joined together using an Ag—Ti brazing filler metal. In Patent Documents 2 and 3, a brazing filler metal containing Ti, an active metal, is used, which improves the wettability of the molten brazing filler metal with the ceramic substrate, resulting in good bonding between the ceramic substrate and the copper plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 01-251781 [Patent Document 2] Patent No. 3211856 [Patent Document 3] Patent No. 5757359 Summary of the Invention [Problem to be solved by the invention]

[0006] When joining a copper plate to a ceramic substrate using an Ag-Cu-Ti or Ag-Ti brazing filler metal, the liquid phase bonding material may seep out from the bonding interface. For example, when joining copper pieces punched into a specific shape and arranged in a circuit pattern, the fluidity of the exuded bonding material may cause it to wet and spread to the copper plate surface, resulting in solder stains. The occurrence of solder stains may adversely affect plating and the mounting of semiconductor elements.

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a copper / ceramic bonded body, which can suppress the occurrence of solder stains on the copper plate surface and can produce a copper / ceramic bonded body with excellent bonding reliability, and a method for manufacturing an insulated circuit board. [Means for solving the problem]

[0008] In order to solve these problems and achieve the above object, the present inventors have conducted extensive research and have come to the following findings. During joining, when compounds are generated between the oxygen (O) and nitrogen (N) in the joining material and the active metal (Ti) in the joining material, the fluidity of the liquid phase decreases, making it possible to suppress the occurrence of solder stains on the copper plate surface.

[0009] The present invention has been made based on the above findings. A method for producing a copper / ceramic bonded body of the present invention is a method for producing a copper / ceramic bonded body formed by bonding a copper member made of copper or a copper alloy to a ceramic member, the method comprising the steps of: providing a bonding material between the copper member and the ceramic member; stacking the copper member and the ceramic member with the bonding material interposed therebetween; and bonding the laminated copper member and the ceramic member, which have the bonding material interposed therebetween, by heat treatment in a vacuum atmosphere while applying pressure to the copper member and the ceramic member in the stacking direction, the bonding material comprising Ag powder having an oxygen concentration of less than 0.3 mass%, an active metal powder, and an organic compound containing O and N in its structure, the organic compound having a thermal decomposition temperature (the temperature at which a weight loss rate of 95% or less is measured by TG-DTA) exceeding 300°C, and the content of the organic compound in the bonding material being in the range of 3 mass% to 10 mass%.

[0010] According to this method for producing a copper / ceramic bonded body, the bonding material contains an active metal powder and an organic compound containing O and N in its structure. The organic compound has a thermal decomposition temperature (the temperature at which the weight loss rate reaches 95% or less in TG-DTA) of over 300°C. The content of the organic compound in the bonding material is 3 mass% or more. Therefore, the active metal reacts with the O and N contained in the organic compound to generate a compound of the active metal. This reduces the fluidity of the liquid phase and suppresses the occurrence of solder stains on the copper sheet surface. In addition, since the Ag powder has a low oxygen concentration and the content of organic compounds containing O and N in the structure is 10 mass% or less, excessive consumption of the active metal by oxygen (O) contained in the Ag powder and O and N in the organic compounds is suppressed, making it possible to firmly bond the copper member and the ceramic member.

[0011] In the method for producing a copper / ceramic bonded body of the present invention, it is preferable that a weight ratio A / B of a content A of the active metal powder to a content B of the organic compound in the bonding material is in the range of 0.5 to 3.5. In this case, the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is set to 0.5 or more, so that the content of the active metal is secured, the active metal promotes the interfacial reaction, and it becomes possible to bond the copper member and the ceramic member more firmly. On the other hand, since the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is set to 3.5 or less, the content of the organic compound can be secured, the active metal compound can be sufficiently generated, the fluidity of the liquid phase can be reliably reduced, and the occurrence of solder stains on the copper plate surface can be further suppressed.

[0012] The method for manufacturing an insulated circuit board of the present invention is a method for manufacturing an insulated circuit board in which a copper plate made of copper or a copper alloy and a ceramic substrate are bonded together, the method comprising the steps of: a bonding material disposing step of disposing a bonding material between the copper plate and the ceramic substrate; a laminating step of stacking the copper plate and the ceramic substrate with the bonding material interposed between them in the laminating direction; and a bonding step of heat-treating the copper plate and the ceramic substrate, which have been laminated with the bonding material interposed between them, in a vacuum atmosphere while applying pressure in the laminating direction. The bonding material contains Ag powder with an oxygen concentration of less than 0.3 mass%, active metal powder, and an organic compound containing O and N in its structure, and the organic compound has a thermal decomposition temperature (the temperature at which the weight loss rate reaches 95% or less by TG-DTA) exceeding 300°C, and the content of the organic compound in the bonding material is within the range of 3 mass% to 10 mass%.

[0013] According to this method for manufacturing an insulated circuit board, the bonding material contains an active metal powder and an organic compound containing O and N in its structure. The organic compound has a thermal decomposition temperature (the temperature at which the weight loss rate reaches 95% or less in TG-DTA) of over 300°C. The content of the organic compound in the bonding material is 3 mass% or more. Therefore, the active metal reacts with the O and N contained in the organic compound to generate a compound of the active metal. This reduces the fluidity of the liquid phase and suppresses the occurrence of solder stains on the copper plate surface. In addition, the Ag powder has a low oxygen concentration, and the content of organic compounds containing O and N in the structure is 10 mass% or less. This prevents the active metal from being excessively consumed by oxygen (O) contained in the Ag powder or O and N in the organic compounds, making it possible to firmly bond the copper plate and ceramic substrate.

[0014] In the method for producing an insulating circuit board of the present invention, it is preferable that the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound in the bonding material is within the range of 0.5 to 3.5. In this case, the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is set to 0.5 or more, so that the content of the active metal is secured, the active metal promotes the interfacial reaction, and it becomes possible to bond the copper member and the ceramic member more firmly. On the other hand, since the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is set to 3.5 or less, the content of the organic compound can be secured, the active metal compound can be sufficiently generated, the fluidity of the liquid phase can be reliably reduced, and the occurrence of solder stains on the copper plate surface can be further suppressed. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for manufacturing a copper / ceramic bonded body that can suppress the occurrence of solder stains on the copper plate surface and that can produce a copper / ceramic bonded body with excellent bonding reliability, and a method for manufacturing an insulated circuit board. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic explanatory diagram of a power module using an insulating circuit board (copper / ceramic bonded body) according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged explanatory view of an insulating circuit board (copper / ceramic bonded body) according to an embodiment of the present invention. [Figure 3] FIG. 1 is a flow diagram showing a method for producing an insulating circuit board (copper / ceramic bonded body) according to an embodiment of the present invention. [Figure 4] 1A to 1C are explanatory diagrams showing a method for producing an insulating circuit board (copper / ceramic bonded body) according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are specifically described to provide a better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional proportions of each component may not necessarily be the same as those in reality.

[0018] The copper / ceramic bonded body of this embodiment is an insulating circuit board 10 formed by bonding a ceramic substrate 11 as a ceramic member made of ceramic to a copper plate 22 (circuit layer 12) and a copper plate 23 (metal layer 13) as copper members made of copper or a copper alloy. Fig. 1 shows a power module 1 including the insulating circuit board 10 of this embodiment.

[0019] This power module 1 includes an insulating circuit board 10 on which a circuit layer 12 and a metal layer 13 are arranged, a semiconductor element 3 joined to one surface (the upper surface in FIG. 1) of the circuit layer 12 via a solder layer 2, and a heat sink 31 arranged on the other side (the lower side in FIG. 1) of the metal layer 13.

[0020] The semiconductor element 3 is made of a semiconductor material such as Si, etc. The semiconductor element 3 and the circuit layer 12 are joined via the solder layer 2. The solder layer 2 is made of, for example, an Sn--Ag based, Sn--In based, or Sn--Ag--Cu based solder material.

[0021] The heat sink 31 is used to dissipate heat on the insulating circuit board 10 side. The heat sink 31 is made of aluminum or an aluminum alloy with good thermal conductivity, and in this embodiment, it is made of A6063 alloy. The thickness of the heat sink 31 is set within the range of 3 mm to 10 mm. The heat sink 31 and the metal layer 13 of the insulating circuit board 10 are bonded together by solid-state diffusion bonding.

[0022] As shown in Figures 1 and 2, the insulating circuit board 10 in this embodiment includes a ceramic substrate 11, a circuit layer 12 disposed on one surface (the upper surface in Figure 1) of the ceramic substrate 11, and a metal layer 13 disposed on the other surface (the lower surface in Figure 1) of the ceramic substrate 11.

[0023] The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13 and is made of ceramics with excellent insulating properties. Aluminum nitride, silicon nitride, alumina, etc. can be used as the ceramic substrate 11. In this embodiment, the ceramic substrate 11 is made of silicon nitride. The thickness of the ceramic substrate 11 is set within a range of 0.2 mm to 1.5 mm, and in this embodiment, it is set to 0.32 mm.

[0024] As shown in Fig. 4, the circuit layer 12 is formed by bonding a copper plate 22 (copper member) made of copper or a copper alloy to one surface of the ceramic substrate 11. As the copper or copper alloy, oxygen-free copper, tough pitch copper, or the like can be used. In this embodiment, the copper plate 22 constituting the circuit layer 12 is punched out from a rolled sheet of oxygen-free copper. A circuit pattern is formed on this circuit layer 12 by bonding the above-mentioned copper plate 22 in a pattern, and one surface (the upper surface in FIG. 1) serves as a mounting surface on which the semiconductor element 3 is mounted. The thickness of the circuit layer 12 is set within a range of 0.1 mm to 3.0 mm, and is set to 0.8 mm in this embodiment.

[0025] As shown in FIG. 4, the metal layer 13 is formed by joining a copper plate 23 made of copper or a copper alloy to the other surface (the lower surface in FIG. 4) of the ceramic substrate 11. In this embodiment, the metal layer 13 is formed by bonding a copper plate 23 made of a rolled sheet of oxygen-free copper to the ceramic substrate 11. The thickness of the copper plate 23 that will become the metal layer 13 is set within the range of 0.1 mm to 3.0 mm, and in this embodiment, it is set to 0.8 mm.

[0026] As shown in FIG. 2, a bonding layer 15 is formed at the bonding interface between the circuit layer 12 and the ceramic substrate 11 and between the metal layer 13 and the ceramic substrate 11. The bonding layer 15 is formed by melting and solidifying a bonding material 25, which will be described later.

[0027] A method for manufacturing the insulating circuit board 10 of this embodiment will be described below with reference to FIGS.

[0028] (Joint material placement process S01) First, as shown in FIG. 4, bonding materials 25 are disposed between the copper plate 22 that will become the circuit layer 12 and the ceramic substrate 11, and between the copper plate 23 that will become the metal layer 13 and the ceramic substrate 11, respectively. In this embodiment, an Ag-Ti paste containing Ag powder and active metal powder (Ti in this embodiment) is printed as a bonding material 25 between the copper plate 22 that becomes the circuit layer 12 and the ceramic substrate 11, and between the copper plate 23 that becomes the metal layer 13 and the ceramic substrate 11.

[0029] The active metal powder may be one or more powders selected from the group consisting of Ti, Zr, Nb, and Hf. Hydrides of these elements may also be used. The average particle size of the active metal powder is preferably in the range of 1 μm to 20 μm.

[0030] In this embodiment, the bonding material 25 contains Ag powder with an oxygen concentration of less than 0.3 mass%, active metal powder, and an organic compound containing O and N in its structure. The organic compound has a thermal decomposition temperature (the temperature at which the weight loss rate becomes 95% or less by TG-DTA) of more than 300°C. In addition to these organic compounds, a common solvent such as α-terpineol can be used as the solvent, and a resin such as a cellulose resin or an acrylic resin may also be added. The thermal decomposition temperature (the temperature at which the weight loss rate reached 95% or less in TG-DTA) was determined by measuring the organic compound in a TG-DTA apparatus (Thermo Plus EVO manufactured by Rigaku Corporation) at a heating rate of 10°C / min under an argon atmosphere, and the temperature at which the weight loss rate reached 95% or less was taken as the thermal decomposition temperature.

[0031] Here, Ag powder with an oxygen concentration of less than 0.3 mass% can be produced by, for example, gas atomization. Specifically, Ag powder is produced by melting silver and blowing it out of a nozzle using an inert gas. The use of an inert gas prevents oxygen from being mixed into the Ag powder, making it possible to obtain Ag powder with a low oxygen concentration. Here, the oxygen concentration in the Ag powder is preferably 0.25 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less. The average particle size of the Ag powder is preferably in the range of 0.5 μm to 20 μm.

[0032] As the organic compound containing O or N in its structure, it is preferable to use an organic compound that has, for example, a carboxy group, a hydroxy group, an amide group, an amino group, a cyano group, a nitro group, or a nitroso group, and whose thermal decomposition temperature (the temperature at which the weight loss rate becomes 95% or less in TG-DTA) exceeds 300°C. Specific examples include polyacrylic acid-polymethyl acrylate copolymer, polyvinyl alcohol, carboxymethyl cellulose, cellulose, polyvinyl butyral, polyoxyethylene alkylamine, alkyl alkanolamide, alkylamine salt, alkyl betaine, polyamine, and polycarboxylic acid.

[0033] In this embodiment, the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound in the bonding material 25 is preferably in the range of 0.5 to 3.5. Here, by setting the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound to be 0.5 or more, the amount of active metal can be secured, and this active metal can promote the interfacial reaction. On the other hand, by setting the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound to be 3.5 or less, it is possible to generate a sufficient amount of active metal compounds and reliably reduce the fluidity of the liquid phase.

[0034] The lower limit of the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is more preferably 0.75 or more, and even more preferably 1 or more. On the other hand, the upper limit of the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound is more preferably 2.5 or less, and even more preferably 2 or less.

[0035] (Lamination process S02) Next, a copper plate 22 is laminated on one surface (the upper surface in FIG. 4) of the ceramic substrate 11 with a bonding material 25 interposed therebetween. Furthermore, a copper plate 23 is laminated on the other surface (the lower surface in FIG. 4) of the ceramic substrate 11 with a bonding material 25 interposed therebetween.

[0036] (Joining process S03) Next, the copper plate 22, bonding material 25, ceramic substrate 11, bonding material 25, and copper plate 23 are loaded into a vacuum heating furnace and heated while being pressurized in the stacking direction (pressure of 0.01 MPa to 3.5 MPa) to melt the bonding material 25. If necessary, the bonding material may be dried to volatilize the solvent. Then, the molten bonding material 25 is solidified to form a bonding layer 15, bonding the copper plate 22 to the ceramic substrate 11 and the ceramic substrate 11 to the copper plate 23. In this embodiment, the pressure inside the vacuum heating furnace is 10 -6 Pa or more 10 -3 The pressure is set to a range of 790°C to 850°C, and the heating time is set to a range of 1 minute to 60 minutes.

[0037] In this bonding step S03, a liquid phase is generated at the interface between the copper plates 22, 23 and the ceramic substrate 11. However, since the bonding material 25 contains 3 mass% or more of an organic compound containing O and N, the active element (Ti) contained in the bonding material 25 reacts with the O and N in the organic compound to generate a Ti compound, which reduces the fluidity of the liquid phase. This makes it possible to suppress the occurrence of solder stains on the surfaces of the copper plates. Furthermore, the bonding material 25 contains Ag powder with an oxygen concentration of less than 0.3 mass % and the content of organic compounds containing O and N is 10 mass % or less, so that excessive generation of Ti compounds can be suppressed.

[0038] In this manner, the copper plate 22, the ceramic substrate 11, and the copper plate 23 are joined together to produce the insulating circuit board 10 of this embodiment.

[0039] (Heat sink bonding process S04) Next, a heat sink 31 is laminated on the other side of the metal layer 13 of the insulating circuit board 10, and the heat sink laminate formed by laminating the insulating circuit board 10 and the heat sink 31 is loaded into a vacuum heating furnace while being pressurized in the lamination direction using a pressure device, and is maintained at a heating temperature below the eutectic temperature of aluminum and copper, thereby solid-state diffusion bonding the metal layer 13 and the heat sink 31.

[0040] (Semiconductor element bonding process S05) Next, the semiconductor element 3 is joined to one surface of the circuit layer 12 of the insulating circuit board 10 by soldering. Through the above steps, the power module 1 shown in FIG. 1 is manufactured.

[0041] According to the manufacturing method of the insulated circuit board (copper / ceramic bonded body) of this embodiment configured as described above, the bonding material 25 disposed between the copper plates 22, 23 and the ceramic substrate 11 contains an active metal powder and an organic compound containing O and N in its structure. The organic compound has a thermal decomposition temperature (the temperature at which the weight loss rate becomes 95% or less by TG-DTA) of over 300°C. The content of the organic compound containing O and N in its structure is 3 mass% or more. Therefore, the active metal reacts with the O and N contained in the organic compound to generate a compound of the active metal. This reduces the fluidity of the liquid phase and suppresses solder stains on the surfaces of the copper plates 22, 23. Furthermore, the bonding material 25 contains Ag powder with a low oxygen concentration, and the content of organic compounds containing O and N in its structure is 10 mass% or less. This prevents the active metal from being consumed by oxygen (O) contained in the Ag powder or O and N in the organic compounds, making it possible to firmly bond the circuit layer 12 and metal layer 13 to the ceramic substrate 11.

[0042] Furthermore, in this embodiment, when the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound containing O and N in its structure is 0.5 or more, the amount of active metal (Ti) is ensured, and this active metal (Ti) can promote the interfacial reaction, making it possible to further firmly bond the circuit layer 12 and metal layer 13 to the ceramic substrate 11. On the other hand, when the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound containing O and N in its structure is 3.5 or less, a sufficient amount of active metal (Ti) compound is generated, the fluidity of the liquid phase is reliably reduced, and solder staining on the surface of the copper plates 22 and 23 can be further suppressed.

[0043] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention. For example, in this embodiment, the circuit layer and the metal layer are both described as being made of copper or a copper alloy, but this is not limited to this and any structure in which a ceramic substrate and a copper plate are joined together may be used.

[0044] In addition, in the present embodiment, a power module is described as being configured by mounting power semiconductor elements on the circuit layer of an insulating circuit board, but this is not limiting. For example, an LED module may be configured by mounting LED elements on an insulating circuit board, or a thermoelectric module may be configured by mounting thermoelectric elements on the circuit layer of an insulating circuit board. [Example]

[0045] A confirmation experiment conducted to confirm the effectiveness of the present invention will be described.

[0046] First, the bonding materials shown in Table 1 were prepared. The Ag powder was produced by gas atomization using Ar gas. The Ag powder, active metal powder, and organic compound were as shown in Table 1, with the remainder being a solvent (α-terpineol). Additionally, a ceramic substrate (40 mm×40 mm, thickness shown in Table 2) and a copper plate (38 mm×38 mm, thickness shown in Table 2) were prepared. The above-mentioned bonding material was applied to the surface of the ceramic substrate to a thickness of 10 μm, and a copper plate was laminated with the bonding material interposed therebetween.

[0047] The obtained insulating circuit board (copper / ceramic bonded body) was evaluated for bonding rate and solder staining as follows.

[0048] (Joining rate) The bonding rate between the copper plate (circuit layer) and the ceramic substrate was evaluated. Specifically, in an insulated circuit board, the bonding rate at the interface between the circuit layer and the ceramic substrate was evaluated using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.) and calculated using the following formula. Since peeling is indicated by a white area within the bond in an image obtained by binarizing the ultrasonic flaw detector image, the area of ​​this white area was taken as the peeling area. (Joining rate)={(Circuit layer area)-(Non-bonding area)} / (Circuit layer area)×100

[0049] (wax stain) The width of the wax stain was measured as follows. The circuit layer surface was visually observed from above, and the area where the brazing filler metal had spread was considered to be a brazing stain. The distance from the edge of the circuit layer to the tip of the brazing stain was measured for each side. The point with the greatest distance was taken as the width of the brazing stain, and measurements were taken for five bonded pieces under each condition and the average was calculated. If the width was 300 μm or less, it was rated as "A," if it was more than 300 μm but not more than 600 μm, it was rated as "B," and if it was more than 600 μm, it was rated as "C."

[0050] [Table 1]

[0051] [Table 2]

[0052] In Comparative Example 1, in which the content of the organic compound containing O and N in the structure was 15 mass%, the bonding rate between the copper plate and the ceramic substrate was as low as 93.8%. This is presumably because the active metal contained in the bonding material was consumed by the O and N in the organic compound. In Comparative Example 2, in which the content of organic compounds containing O and N in the structure was 1 mass%, the evaluation of wax staining was "C." This is presumably because active metal compounds were not sufficiently generated, and the fluidity of the liquid phase could not be reduced. In Comparative Example 3, in which the oxygen concentration of the Ag powder in the bonding material was 0.62 mass%, the bonding rate was low at 91.6%. This is presumably because the active metal was consumed by oxygen (O) contained in the Ag powder.

[0053] In contrast, in Example 1-9 of the present invention, in which the oxygen concentration of the Ag powder was less than 0.3 mass% and the content of organic compounds containing O and N in the structure was in the range of 3 mass% to 10 mass%, the bonding rate between the copper plate and the ceramic substrate was 95.3% or more, and the evaluation of solder stains was "A" or "B". In addition, in Examples 1-6 and 9 of the present invention, in which the weight ratio A / B of the content A of the active metal powder to the content B of the organic compound containing O and N in its structure was within the range of 0.5 to 3.5, the bonding rate between the copper plate and the ceramic substrate was 96.4% or more, and the evaluation of solder stains was "A."

[0054] From the results of the above confirmatory experiments, it was confirmed that the present invention can provide a method for manufacturing a copper / ceramic bonded body (insulated circuit board) that can suppress the occurrence of solder stains on the copper plate surface and can produce a copper / ceramic bonded body (insulated circuit board) with excellent bonding reliability. [Explanation of symbols]

[0055] 10 Insulated circuit board (copper / ceramic bonded body) 11 Ceramic substrate (ceramic component) 12 Circuit layer (copper material) 13 Metal layer (copper material)

Claims

1. A method for producing a copper / ceramic bonded body in which a copper member made of copper or a copper alloy and a ceramic member are bonded, comprising: a bonding material disposing step of disposing a bonding material between the copper member and the ceramic member; a lamination step of laminating the copper member and the ceramic member via the bonding material; a joining step of joining the copper member and the ceramic member stacked via the joining material by heat treatment in a vacuum atmosphere while applying pressure to the copper member and the ceramic member in the stacking direction, the joining material contains Ag powder having an oxygen concentration of less than 0.3 mass%, an active metal powder, and an organic compound containing O and N in its structure, the organic compound having a thermal decomposition temperature (temperature at which a weight loss rate reaches 95% or less in TG-DTA) exceeding 300°C, and the content of the organic compound in the joining material is within a range of 3 mass% to 10 mass%.

2. 2. The method for producing a copper / ceramic joined body according to claim 1, wherein a weight ratio A / B of a content A of the active metal powder to a content B of the organic compound in the joining material is in the range of 0.5 to 3.

5.

3. A method for manufacturing an insulating circuit board in which a copper plate made of copper or a copper alloy and a ceramic substrate are bonded, comprising: a bonding material disposing step of disposing a bonding material between the copper plate and the ceramic substrate; a lamination step of laminating the copper plate and the ceramic substrate via the bonding material; a bonding step of bonding the copper plate and the ceramic substrate stacked via the bonding material by heat treatment in a vacuum atmosphere while applying pressure to the copper plate and the ceramic substrate in a stacking direction, a bonding material that contains Ag powder having an oxygen concentration of less than 0.3 mass%, an active metal powder, and an organic compound that contains O and N in its structure, the organic compound having a thermal decomposition temperature (temperature at which a weight loss rate reaches 95% or less in TG-DTA) exceeding 300°C, and a content of the organic compound in the bonding material that is within a range of 3 mass% to 10 mass%.

4. 4. The method for manufacturing an insulating circuit board according to claim 3, wherein a weight ratio A / B of a content A of the active metal powder to a content B of the organic compound in the bonding material is within a range of 0.5 to 3.5.

Images