Copper-ceramic bonding agent, insulating circuit board, manufacturing method of copper-ceramic bonding agent and manufacturing method of insulating circuit board

Abstract

A copper-ceramic composite (10) is formed by joining a copper component (12) made of copper or a copper alloy and a ceramic component (11) made of oxygen-containing ceramic. A magnesium oxide layer (41) is formed between the copper component (12) and the ceramic component (11) on the side of the ceramic component (11). An active metal oxide phase is dispersed inside the copper layer (45) in contact with the magnesium oxide layer (41). The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf.

Description

Technical Field

[0001] This invention relates to a copper-ceramic bond formed by joining a copper component made of copper or a copper alloy and a ceramic component, an insulating circuit board formed by joining a copper plate made of copper or a copper alloy to the surface of a ceramic substrate, a method for manufacturing the copper-ceramic bond, and a method for manufacturing the insulating circuit board.

[0002] This application claims priority based on Japanese Patent Application No. 2019-151166, filed on August 21, 2019, the contents of which are incorporated herein by reference. Background Technology

[0003] The power module, LED module, and thermoelectric module have the following structure: power semiconductor elements, LED elements, and thermoelectric elements are bonded to an insulating circuit board on one side of the insulating layer, on which a circuit layer made of conductive material is formed.

[0004] For example, power semiconductor devices used for controlling high-power applications such as wind power generation, electric vehicles, and hybrid electric vehicles generate a lot of heat during operation. Therefore, as the substrate for mounting these power semiconductor devices, an insulating circuit board has been widely used. This insulating circuit board has a ceramic substrate and a circuit layer formed by bonding a highly conductive metal plate to one side of the ceramic substrate. Additionally, an insulating circuit board with a metal layer formed by bonding a metal plate to the other side of the ceramic substrate has also been provided.

[0005] For example, Patent Document 1 proposes an insulating circuit board in which a circuit layer and a metal layer are formed by bonding a copper plate to one and the other sides of a ceramic substrate. In Patent Document 1, a copper plate is placed on one and the other sides of the ceramic substrate with an Ag-Cu-Ti based solder in between, and the copper plate is bonded by heat treatment (so-called active metal brazing method). In this active metal brazing method, a solder containing Ti as an active metal is used, which improves the wettability of the molten solder with the ceramic substrate, thus enabling good bonding between the ceramic substrate and the copper plate.

[0006] Furthermore, Patent Document 2 proposes using Cu-Mg-Ti solder to bond an insulating circuit board between a ceramic substrate and a copper plate.

[0007] In this patent document 2, the structure is joined by heating at 560-800°C in a nitrogen atmosphere. In this structure, the Mg in the Cu-Mg-Ti alloy sublimates without remaining at the joining interface and does not substantially form titanium nitride (TiN).

[0008] Patent Document 1: Japanese Patent No. 3211856 (B)

[0009] Patent Document 2: Japanese Patent No. 4375730 (B)

[0010] However, in high-temperature semiconductor devices using SiC and similar materials, the high-density mounting necessitates ensuring the operation of the insulating circuit board at even higher temperatures. Therefore, even under more severe thermal cycling conditions than before, ensuring the reliability of the bonding between the copper plate and the ceramic substrate is required.

[0011] Furthermore, ultrasonic bonding of terminals and the like is sometimes performed in the circuit layer of the aforementioned insulating circuit board.

[0012] In the insulating circuit board described in Patent Documents 1 and 2, when ultrasonic waves are applied to bond terminal materials, cracks may form at the bonding interface, potentially leading to the peeling of the circuit layer. Summary of the Invention

[0013] The present invention was made in view of the above circumstances, and its object is to provide a copper-ceramic joint, an insulating circuit board, a method for manufacturing the copper-ceramic joint, and a method for manufacturing the insulating circuit board, which can ensure the bonding reliability of copper and ceramic components even under severe thermal cycling, and can suppress the peeling of ceramic and copper components even when ultrasonic bonding is performed.

[0014] To address the aforementioned issues, one aspect of the present invention provides a copper-ceramic joint (hereinafter referred to as "the copper-ceramic joint of the present invention") which is a copper-ceramic joint formed by joining a copper component made of copper or a copper alloy and a ceramic component made of oxygen-containing ceramic. The joint is characterized in that a magnesium oxide layer is formed between the copper component and the ceramic component on the side of the ceramic component, and an active metal oxide phase is dispersed within the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed from oxides of one or more active metals selected from Ti, Zr, Nb, and Hf.

[0015] According to the copper-ceramic joint of the present invention, a magnesium oxide layer is formed between the copper component and the ceramic component. Therefore, the magnesium oxide layer can reduce the thermal stress caused by the difference in the coefficients of thermal expansion between the copper component and the ceramic component, thereby improving the reliability of the joint after thermal cycling.

[0016] Furthermore, an active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf. Therefore, the bonding interface is strengthened, and even when ultrasonic waves are applied to the bonding body for ultrasonic bonding of terminal materials, peeling of the ceramic component from the copper component or cracking of the ceramic substrate can be suppressed.

[0017] In this invention, the thickness of the magnesium oxide layer is preferably in the range of 50 nm or more and 1000 nm or less in the copper-ceramic composite.

[0018] At this time, the thickness of the magnesium oxide layer formed between the copper component and the ceramic component is in the range of 50 nm or more and 1000 nm or less. Therefore, the magnesium oxide layer can effectively reduce the thermal stress caused by the difference in the thermal expansion coefficients of the copper component and the ceramic component, thereby further improving the bonding reliability after thermal cycling.

[0019] Furthermore, in the copper-ceramic composite of the present invention, preferably, any one or two of Cu particles and Cu-active metal compound particles are dispersed inside the magnesium oxide layer.

[0020] At this point, the strength of the magnesium oxide layer formed at the bonding interface is improved by the aforementioned Cu particles and compound particles, thereby further suppressing the peeling of the ceramic component from the copper component or the generation of cracks in the ceramic substrate under ultrasonic load.

[0021] Furthermore, in the copper-ceramic composite of the present invention, the Cu particles and the compound particles dispersed inside the magnesium oxide layer preferably have a circular equivalent diameter of 10 nm or more and 100 nm or less.

[0022] At this point, the spherical equivalent diameter of the Cu particles and compound particles is in the range of 10 nm or more and 100 nm or less, thus reliably improving the strength of the magnesium oxide layer formed at the bonding interface, thereby further suppressing the peeling of the ceramic component from the copper component or the generation of cracks in the ceramic substrate when subjected to ultrasonic load.

[0023] Furthermore, in the copper-ceramic composite of the present invention, the active metal is preferably Ti.

[0024] At this time, a titanium oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer, which can reliably strengthen the bonding interface and further suppress the peeling of the ceramic component from the copper component or the generation of cracks in the ceramic substrate, even when subjected to ultrasonic load.

[0025] Another aspect of the insulating circuit board of the present invention (hereinafter referred to as "the insulating circuit board of the present invention") is an insulating circuit board formed by bonding a copper plate made of copper or copper alloy to the surface of a ceramic substrate made of oxygen-containing ceramic. The characteristic is that a magnesium oxide layer is formed on the side of the ceramic substrate between the ceramic substrate and the copper plate, and an active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf.

[0026] According to the insulating circuit substrate of the present invention, a magnesium oxide layer is formed between the copper plate and the ceramic substrate. Therefore, the magnesium oxide layer can reduce the thermal stress caused by the difference in the coefficients of thermal expansion between the copper plate and the ceramic component, thereby improving the bonding reliability after thermal cycling.

[0027] Furthermore, an active metal oxide phase is dispersed within the copper layer in contact with the magnesium oxide layer. This active metal oxide phase is formed from oxides of one or more active metals selected from Ti, Zr, Nb, and Hf. Therefore, the bonding interface is strengthened, and even when subjected to ultrasonic loads, it can suppress the peeling of the ceramic substrate from the copper plate or the generation of cracks in the ceramic substrate.

[0028] In this invention, the thickness of the magnesium oxide layer is preferably in the range of 50 nm or more and 1000 nm or less in the insulating circuit substrate.

[0029] At this time, the thickness of the magnesium oxide layer formed between the copper plate and the ceramic substrate is in the range of 50 nm or more and 1000 nm or less. Therefore, the magnesium oxide layer can effectively reduce the thermal stress caused by the difference in the thermal expansion coefficients of the copper plate and the ceramic substrate, thereby further improving the bonding reliability after thermal cycling.

[0030] Furthermore, in the insulating circuit substrate of the present invention, preferably, any one or two of Cu particles and Cu-active metal compound particles are dispersed inside the magnesium oxide layer.

[0031] At this point, the strength of the magnesium oxide layer formed at the bonding interface is improved by the aforementioned Cu particles and compound particles, thereby further suppressing the peeling of the ceramic substrate from the copper plate or the generation of cracks in the ceramic substrate under ultrasonic load.

[0032] Furthermore, in the insulating circuit substrate of the present invention, the Cu particles and the compound particles dispersed inside the magnesium oxide layer preferably have a circular equivalent diameter of 10 nm or more and 100 nm or less.

[0033] At this point, the spherical equivalent diameter of the Cu particles and compound particles is in the range of 10 nm or more and 100 nm or less, thus reliably improving the strength of the magnesium oxide layer formed at the bonding interface, thereby further suppressing the peeling of the ceramic substrate from the copper plate or the generation of cracks in the ceramic substrate under ultrasonic load.

[0034] Furthermore, in the insulating circuit substrate of the present invention, the active metal is preferably Ti.

[0035] At this time, a titanium oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer, which can reliably strengthen the bonding interface and further suppress the peeling of the ceramic substrate from the copper plate or the generation of cracks in the ceramic substrate, even when subjected to ultrasonic loads.

[0036] Another aspect of the present invention provides a method for manufacturing a copper-ceramic bond (hereinafter referred to as "the method for manufacturing a copper-ceramic bond of the present invention"), characterized by comprising: an active metal and Mg preparation step, wherein one or more active metals and Mg selected from Ti, Zr, Nb, and Hf are prepared between the copper component and the ceramic component; a lamination step, wherein the copper component and the ceramic component are laminated using the active metal and Mg; and a bonding step, wherein the copper component and the ceramic component laminated using the active metal and Mg are bonded by heat treatment under a vacuum atmosphere while the laminated copper component and the ceramic component are pressurized along the lamination direction, wherein the amount of active metal is set at 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the Mg content is set at 14 μmol / cm. 2 Above and 180 μmol / cm 2 Within the following ranges, in the bonding process, the heating rate is set to 5°C / min or higher within the temperature range of 480°C or higher and 650°C or lower, the holding temperature is set to 650°C or higher and 850°C or lower, and the holding time at the holding temperature is set to 10 min or higher and 180 min or lower.

[0037] According to the manufacturing method of the copper-ceramic composite with this structure, in the active metal and Mg preparation step, the amount of active metal is 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the amount of Mg is 14 μmol / cm³. 2 Above and 180 μmol / cm 2 Within the following range, the liquid phase required for the interfacial reaction can be adequately obtained. Therefore, copper components and ceramic components can be reliably joined.

[0038] Furthermore, in the bonding process, the heating rate is 5°C / min or higher within the temperature range of 480°C to 650°C, and the holding temperature is maintained within the range of 650°C to 850°C, with a holding time of 10 min to 180 min. Therefore, the liquid phase required for the interfacial reaction can be maintained for a certain period of time, promoting a uniform interfacial reaction and forming a magnesium oxide layer at the bonding interface. In addition, an active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb, and Hf.

[0039] The method for manufacturing the insulating circuit board of the present invention is a method for manufacturing the above-mentioned insulating circuit board, characterized by comprising: an active metal and Mg preparation step, wherein one or more active metals and Mg selected from Ti, Zr, Nb and Hf are prepared between the copper plate and the ceramic substrate; a lamination step, wherein the copper plate and the ceramic substrate are laminated using the active metal and Mg; and a bonding step, wherein the copper plate and the ceramic substrate laminated with the active metal and Mg are bonded by heat treatment under a vacuum atmosphere while the laminated copper plate and the ceramic substrate are pressurized along the lamination direction, wherein the amount of active metal is set at 0.4 μmol / cm³ in the active metal and Mg preparation step. 2 Above and 47.0 μmol / cm 2 Within the following range, the Mg content is set at 14 μmol / cm. 2 Above and 180 μmol / cm 2 Within the following ranges, in the bonding process, the heating rate is set to 5°C / min or higher within the temperature range of 480°C or higher and 650°C or lower, the holding temperature is set to 650°C or higher and 850°C or lower, and the holding time at the holding temperature is set to 10 min or higher and 180 min or lower.

[0040] According to the manufacturing method of the insulating circuit board with this structure, in the active metal and Mg preparation step, the amount of active metal is 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the amount of Mg is 14 μmol / cm³. 2 Above and 180 μmol / cm 2 Within the following range, the liquid phase required for the interfacial reaction can be adequately obtained. Therefore, the copper plate and the ceramic substrate can be reliably bonded.

[0041] Furthermore, in the bonding process, the heating rate is 5°C / min or higher within the temperature range of 480°C to 650°C, and the holding temperature is maintained within the range of 650°C to 850°C, with a holding time of 10 min to 180 min. Therefore, the liquid phase required for the interfacial reaction can be maintained for a certain period of time, promoting a uniform interfacial reaction and forming a magnesium oxide layer at the bonding interface. In addition, an active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb, and Hf.

[0042] According to the present invention, a copper-ceramic joint, an insulating circuit board, a method for manufacturing the copper-ceramic joint, and a method for manufacturing the insulating circuit board are provided, which can ensure the bonding reliability of the copper component and the ceramic component even under harsh thermal cycling conditions, and can suppress the peeling of the ceramic component and the copper component or the generation of cracks in the ceramic substrate even when ultrasonic bonding is performed. Attached Figure Description

[0043] Figure 1 This is a schematic diagram illustrating a power module using an insulating circuit board according to an embodiment of the present invention.

[0044] Figure 2 This is an enlarged illustration of the interface between the circuit layer (metal layer) of the insulating circuit board and the ceramic substrate according to an embodiment of the present invention.

[0045] Figure 3 This is a flowchart of a method for manufacturing an insulating circuit board according to an embodiment of the present invention.

[0046] Figure 4 This is a schematic diagram illustrating a method for manufacturing an insulating circuit board according to an embodiment of the present invention. Detailed Implementation

[0047] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0048] The bonding body involved in this embodiment is an insulating circuit board 10 formed by bonding a ceramic substrate 11, which is a ceramic component made of ceramic, and copper plates 22 (circuit layer 12) and 23 (metal layer 13), which are copper components made of copper or copper alloy. Figure 1 A power module 1 equipped with the insulating circuit board 10 of this embodiment is shown.

[0049] The power module 1 includes: an insulating circuit board 10 provided with a circuit layer 12 and a metal layer 13; on one side of the circuit layer 12 (on Figure 1The semiconductor element 3 (top) is bonded via bonding layer 2; and the other side of the metal layer 13 (on the other side) is disposed of in the metal layer 13. Figure 1 The radiator 30 is located on the lower side (in the middle).

[0050] Semiconductor element 3 is made of semiconductor material such as Si. Semiconductor element 3 is bonded to circuit layer 12 via bonding layer 2.

[0051] The bonding layer 2 is composed of, for example, Sn-Ag, Sn-In, or Sn-Ag-Cu solder.

[0052] The heat sink 30 is used to dissipate heat from the insulating circuit board 10. The heat sink 30 is made of Cu or a Cu alloy; in this embodiment, it is made of phosphorus-deoxidized copper. The heat sink 30 includes a flow path 31 for the flow of cooling fluid.

[0053] In this embodiment, the heat sink 30 and the metal layer 13 are bonded by a solder layer 32 made of solder. The solder layer 32 is made of, for example, Sn-Ag, Sn-In, or Sn-Ag-Cu solder.

[0054] And, as Figure 1 As shown, the insulating circuit board 10 of this embodiment includes a ceramic substrate 11 and a side disposed on the ceramic substrate 11 (in... Figure 1 The circuit layer 12 (top) and the other side of the ceramic substrate 11 (on the top) Figure 1 The metal layer 13 (with the middle layer below) is located below.

[0055] The ceramic substrate 11 is made of oxygen-containing ceramic with excellent insulation and heat dissipation properties; in this embodiment, it is made of alumina (Al2O3). The thickness of the ceramic substrate 11 is, for example, set in the range of 0.2 mm or more and 1.5 mm or less; in this embodiment, it is set to 0.635 mm.

[0056] like Figure 4 As shown, the circuit layer 12 is located on one side of the ceramic substrate 11 (on... Figure 4 The middle part (top) is formed by joining a copper plate 22 made of copper or a copper alloy.

[0057] In this embodiment, the circuit layer 12 is formed by bonding a copper plate 22, which is made of oxygen-free copper rolled plate, to the ceramic substrate 11.

[0058] In addition, the thickness of the copper plate 22 that forms the circuit layer 12 is set in the range of 0.1 mm or more and 2.0 mm or less. In this embodiment, it is set to 0.6 mm.

[0059] like Figure 4 As shown, the metal layer 13 passes through the other side of the ceramic substrate 11 (on the other side). Figure 4 (The middle part is below) is formed by joining copper plates 23 made of copper or copper alloys.

[0060] In this embodiment, the metal layer 13 is formed by bonding a copper plate 23, which is made of an oxygen-free copper rolled plate, to the ceramic substrate 11.

[0061] Furthermore, the thickness of the copper plate 23 that forms the metal layer 13 is set in the range of 0.1 mm or more and 2.0 mm or less; in this embodiment, it is set to 0.6 mm.

[0062] Furthermore, at the interface between the ceramic substrate 11 and the circuit layer 12 (metal layer 13), such as Figure 2 As shown, a magnesium oxide layer 41 is formed on the ceramic substrate 11 side, and a copper layer 45 is formed on the magnesium oxide layer 41.

[0063] The magnesium oxide layer 41 is a layer directly disposed on the ceramic substrate 11. The main component of the magnesium oxide layer 41 is magnesium oxide.

[0064] The copper layer 45 is located between the magnesium oxide layer 41 and the circuit layer 12 (metal layer 13). The main component of the copper layer 45 is copper or a copper alloy, and an active metal oxide phase 46 is dispersed within the copper layer 45. This active metal oxide phase 46 is formed from oxides of one or more active metals selected from Ti, Zr, Nb, and Hf. In this embodiment, Ti is preferably used as the active metal.

[0065] In this embodiment, it is preferred that the thickness of the magnesium oxide layer 41 is in the range of 50 nm or more and 1000 nm or less.

[0066] Furthermore, the thickness of the magnesium oxide layer 41 is preferably 80 nm or more, more preferably 150 nm or more. Additionally, the thickness of the magnesium oxide layer 41 is preferably 700 nm or less, more preferably 500 nm or less.

[0067] The thickness of the copper layer 45 is preferably 0.1 μm or more, more preferably 5 μm or more. On the other hand, the thickness of the copper layer 45 is preferably 80 μm or less, more preferably 60 μm or less.

[0068] Furthermore, in this embodiment, it is preferable that Cu-containing particles 42, composed of any one or two of Cu particles and Cu-active metal compound particles, are dispersed inside the magnesium oxide layer 41.

[0069] Cu particles are a phase composed of Cu present inside the magnesium oxide layer 41. Cu compound particles are a phase composed of Cu present inside the magnesium oxide layer 41 and an active metal (selected from one or more of Ti, Zr, Nb and Hf).

[0070] Examples of Cu-reactive metal compound particles include Cu4Ti, Cu3Ti2, Cu4Ti3, CuTi, CuTi2, CuTi3, Cu5Zr, and Cu51Zr. 14 Cu8Zr3, Cu 10 Zr7, CuZr, Cu5Zr8, CuZr2, etc., Cu 51 Hf 14 Cu8Hf3, Cu 10 Hf7, CuHf2, etc. In addition, in this embodiment, the spherical equivalent diameter of the Cu-containing particles 42 dispersed inside the magnesium oxide layer 41 is preferably in the range of 10 nm or more and 100 nm or less.

[0071] Furthermore, the spherical equivalent diameter of the Cu-containing particles 42 dispersed within the magnesium oxide layer 41 is more preferably 15 nm or more, and even more preferably 20 nm or more. On the other hand, the spherical equivalent diameter of the Cu-containing particles 42 is more preferably 70 nm or less, and even more preferably 50 nm or less.

[0072] The following is for reference. Figure 3 and Figure 4 The manufacturing method of the insulating circuit board 10 according to this embodiment will be described.

[0073] (Active metal and Mg preparation process S01)

[0074] First, prepare a ceramic substrate 11 made of alumina (Al2O3), such as... Figure 4 As shown, one or more active metals selected from Ti, Zr, Nb and Hf and Mg are respectively disposed between the copper plate 22, which forms the circuit layer 12 and the ceramic substrate 11, and between the copper plate 23, which forms the metal layer 13 and the ceramic substrate 11.

[0075] In this embodiment, Mg foil 25 and active metal foil 26 are disposed between the copper plate 22, which forms the circuit layer 12, and the ceramic substrate 11, and between the copper plate 23, which forms the metal layer 13, and the ceramic substrate 11.

[0076] Here, in the active metal and Mg preparation step S01, the amount of active metal prepared is set to 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the Mg content is set at 14 μmol / cm. 2 Above and 180 μmol / cm 2 Within the following range.

[0077] Furthermore, the preferred amount of active metal is 0.9 μmol / cm³. 2The above is further preferred to be 2.8 μmol / cm. 2 That's all. On the other hand, the preferred amount of active metal is 20 μmol / cm³. 2 Hereinafter, 10 μmol / cm is further preferred. 2 the following.

[0078] Furthermore, the preferred amount of Mg is 21 μmol / cm³. 2 The above is further preferred to be 28 μmol / cm. 2 That's all. On the other hand, the preferred amount of Mg is 107 μmol / cm³. 2 The following is a further preferred value: 72 μmol / cm 2 the following.

[0079] (Lamination process S02)

[0080] Next, the copper plate 22 and the ceramic substrate 11 are laminated together via an active metal foil 26 and a Mg foil 25, and the ceramic substrate 11 and the copper plate 23 are laminated together via an active metal foil 26 and a Mg foil 25.

[0081] (Jointing process S03)

[0082] Next, the stacked copper plate 22, active metal foil 26, Mg foil 25, ceramic substrate 11, Mg foil 25, active metal foil 26, and copper plate 23 are pressurized along the stacking direction and placed in a vacuum furnace for heating to bond the copper plate 22, ceramic substrate 11, and copper plate 23 together.

[0083] Here, regarding the heat treatment conditions in the bonding process S03, the heating rate is 5°C / min or higher within a temperature range of 480°C to 650°C, and the holding temperature is maintained within a range of 650°C to 850°C, with a holding time of 10 min to 180 min. By specifying the heat treatment conditions in this way, the Cu-Mg liquid phase can be maintained at a high temperature at the bonding interface, forming a magnesium oxide layer 41 and a copper layer 45 at the bonding interface. Within the copper layer 45, an active metal oxide phase 46 formed of oxides of one or more active metals selected from Ti, Zr, Nb, and Hf is dispersed.

[0084] Furthermore, the heating rate within the temperature range of 480°C or higher and below 650°C is preferably 7°C / min or higher, and more preferably 9°C / min or higher. On the other hand, there is no particular limitation on the upper limit of the heating rate within the temperature range of 480°C or higher and below 650°C, but it is preferably 15°C / min or lower, and more preferably 12°C / min or lower.

[0085] Furthermore, the holding temperature is preferably 700°C or higher, more preferably 750°C or higher. On the other hand, the holding temperature is preferably 830°C or lower, more preferably 800°C or lower.

[0086] Furthermore, the holding time is preferably 30 minutes or more, and more preferably 45 minutes or more. On the other hand, the holding time is preferably 150 minutes or less, and more preferably 120 minutes or less.

[0087] Furthermore, the pressure load in the joining process S03 is preferably in the range of 0.049 MPa or more and 3.4 MPa or less.

[0088] Furthermore, the vacuum level in the joining process S03 is preferably 1×10⁻⁶. -6 Pa or higher and 5×10 -2 Within the range below Pa.

[0089] As described above, the insulating circuit board 10 of this embodiment is manufactured through the active metal and Mg preparation process S01, the lamination process S02, and the bonding process S03.

[0090] (Radiator joining process S04)

[0091] Next, the heat sink 30 is bonded to the other side of the metal layer 13 of the insulating circuit board 10. The insulating circuit board 10 and the heat sink 30 are stacked with solder and placed in a heating furnace, where the insulating circuit board 10 and the heat sink 30 are soldered together via the solder layer 32.

[0092] (Semiconductor device bonding process S05)

[0093] Next, the semiconductor element 3 is bonded to one side of the circuit layer 12 of the insulating circuit board 10 by soldering.

[0094] Through the above processes, produce Figure 1 The power module 1 shown.

[0095] According to the insulating circuit board 10 (copper-ceramic bonding body) of this embodiment with the above configuration, a magnesium oxide layer 41 is formed between the circuit layer 12 and the metal layer 13 and the ceramic substrate 11. Therefore, the magnesium oxide layer 41 can reduce the thermal stress caused by the difference in the coefficients of thermal expansion between the circuit layer 12 and the metal layer 13 and the ceramic substrate 11, thereby improving the bonding reliability after thermal cycling.

[0096] Furthermore, an active metal oxide phase 46 is dispersed within the copper layer 45 in contact with the magnesium oxide layer 41. This active metal oxide phase 46 is formed from oxides of one or more active metals selected from Ti, Zr, Nb, and Hf, thus strengthening the bonding interface. Therefore, even when ultrasonic waves are applied to the insulating circuit board 10 (copper-ceramic bonding body) to ultrasonically bond terminals or the like to the copper component (circuit layer 12), it is possible to suppress the peeling of the circuit layer 12 and metal layer 13 from the ceramic substrate 11 or the generation of cracks in the ceramic substrate 11.

[0097] Furthermore, in this embodiment, when the thickness of the magnesium oxide layer 41 is in the range of 50 nm or more and 1000 nm or less, the magnesium oxide layer 41 can sufficiently reduce the thermal stress caused by the difference in thermal expansion coefficients between the circuit layer 12 and the metal layer 13 and the ceramic substrate 11, thereby further improving the bonding reliability after thermal cycling.

[0098] Furthermore, in this embodiment, when Cu-containing particles 42, composed of any one or two of Cu particles and Cu-active metal compound particles, are dispersed inside the magnesium oxide layer 41, the strength of the magnesium oxide layer 41 formed at the bonding interface is improved by the Cu-containing particles 42, thereby further suppressing the peeling of the circuit layer 12 and metal layer 13 from the ceramic substrate 11 or the generation of cracks in the ceramic substrate 11 when subjected to ultrasonic loads.

[0099] Furthermore, in this embodiment, when the equivalent diameter of the Cu-containing particles 42 dispersed inside the magnesium oxide layer 41 is in the range of 10 nm or more and 100 nm or less, the strength of the magnesium oxide layer 41 formed at the bonding interface is reliably improved, thereby further suppressing the peeling of the circuit layer 12 and metal layer 13 from the ceramic substrate 11 or the generation of cracks in the ceramic substrate 11 when subjected to ultrasonic loads.

[0100] Furthermore, in this embodiment, when the active metal is Ti, a titanium oxide phase, which is an active metal oxide phase 46, is dispersed inside the copper layer 45 that is in contact with the magnesium oxide layer 41, thereby reliably strengthening the bonding interface. Even when subjected to ultrasonic waves, it can further suppress the peeling of the circuit layer 12 and metal layer 13 from the ceramic substrate 11 or the generation of cracks in the ceramic substrate 11.

[0101] According to the method for manufacturing the insulating circuit board of this embodiment, in the active metal and Mg preparation step 01, the amount of active metal is 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the amount of Mg is 14 μmol / cm³. 2 Above and 180 μmol / cm 2Within the following range, the liquid phase required for the interfacial reaction can be sufficiently obtained. Therefore, the circuit layer 12 and the metal layer 13 can be reliably bonded to the ceramic substrate 11.

[0102] Furthermore, in the bonding process S03, the heating rate is 5°C / min or higher within the temperature range of 480°C or higher and 650°C or lower, and the holding temperature is maintained within the range of 650°C or higher and 850°C or lower, and the holding time at the holding temperature is maintained within the range of 10 min or higher and 180 min or lower. Therefore, the liquid phase required for the interfacial reaction can be maintained for a certain period of time, which can promote a uniform interfacial reaction and form a magnesium oxide layer 41 at the bonding interface. In addition, an active metal oxide phase 46 is dispersed inside the copper layer 45 in contact with the magnesium oxide layer 41. The active metal oxide phase 46 is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf.

[0103] The embodiments of the present invention have been described above, but the present invention is not limited thereto. Appropriate modifications can be made without departing from the technical requirements of the invention.

[0104] For example, this embodiment describes the case where a power module is constructed by mounting semiconductor elements on an insulating circuit board, but it is not limited to this. For example, an LED module can be constructed by mounting LED elements on the circuit layer of the insulating circuit board, or a thermoelectric module can be constructed by mounting thermoelectric elements on the circuit layer of the insulating circuit board.

[0105] Furthermore, in the insulating circuit board of this embodiment, the case where both the circuit layer and the metal layer are made of copper plates made of copper or copper alloys has been described, but it is not limited to this.

[0106] For example, as long as the circuit layer and the ceramic substrate constitute the copper-ceramic bonding body of the present invention, the material or bonding method of the metal layer is not limited. There may be no metal layer, and the metal layer may be made of aluminum or aluminum alloy, or it may be made of a laminate of copper and aluminum.

[0107] On the other hand, as long as the metal layer and the ceramic substrate constitute the copper-ceramic bonding body of the present invention, the material or bonding method of the circuit layer is not limited. The circuit layer can be made of aluminum or aluminum alloy, or it can be made of a stack of copper and aluminum.

[0108] Furthermore, while this embodiment describes a structure in which an active metal foil and a Mg foil are stacked between a copper plate and a ceramic substrate, it is not limited to this; an alloy foil of Mg and an active metal may also be used. Additionally, a thin film composed of Mg, an active metal, or an alloy of Mg and an active metal may be formed at the interface between the ceramic substrate and the copper plate using sputtering or vapor deposition methods.

[0109] It can also replace active metal foil to coat the required amount of the corresponding active metal-containing slurry.

[0110] Similarly, it can replace Mg foil to coat the required amount of Mg-containing slurry.

[0111] Alternatively, only one of the active metal foil and Mg foil can be replaced with a paste. Both the active metal foil and Mg foil can also be replaced with a paste. A paste containing an alloy of Mg and the active metal can also be used.

[0112] MgH2 and active metal hydrides can also be used as fillers in these slurries.

[0113] Example

[0114] The results of the confirmation experiments conducted to verify the effectiveness of the present invention will be described below.

[0115] First, a ceramic substrate (40mm×40mm×0.635mm) made of alumina (Al2O3) was prepared.

[0116] Under the conditions shown in Table 1, a copper plate (37mm × 37mm × 0.3mm thickness) made of oxygen-free copper was bonded to both sides of the ceramic substrate to obtain an insulating circuit board (copper-ceramic bond). Additionally, the vacuum level of the vacuum furnace during bonding was 8 × 10⁻⁶. -3 Pa.

[0117] For the obtained insulating circuit board (copper-ceramic bonding), the thickness of the magnesium oxide layer at the bonding interface, the presence and equivalent diameter of Cu particles (either Cu particles or Cu-active metallized particles) in the magnesium oxide layer, the presence and absence of active metal oxide phases in the copper layer, and ultrasonic bonding were evaluated in the following manner.

[0118] (Magnesium oxide layer)

[0119] The 3μm × 3μm area at the interface between the copper plate and the ceramic substrate was observed using a transmission electron microscope (Titan ChemiSTEM manufactured by FEI) at an accelerating voltage of 200kV and a magnification of 20,000x. The region where Mg and oxygen (O) coexist was designated as the magnesium oxide layer, and the thickness of this region was measured. The evaluation results are shown in Table 2.

[0120] Furthermore, when Cu (Cu phase) was detected in the region where Mg and O coexisted, it was determined to contain Cu particles, and their circumference equivalent diameter was measured. The evaluation results are shown in Table 2.

[0121] (Active metal oxide phase in the copper layer)

[0122] The 3μm × 3μm area of ​​the interface between the copper plate and the ceramic substrate was observed using a transmission electron microscope (Titan ChemiSTEM manufactured by FEI) at an accelerating voltage of 200kV and a magnification of 20,000x. When an active metal and oxygen (O) coexisted in the copper layer, it was determined to have an active metal oxide phase. The evaluation results are shown in Table 2.

[0123] The copper layer is a layer existing between the magnesium oxide layer and the copper plate. The main component of the copper layer is copper or a copper alloy, and an active metal oxide phase formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf is dispersed inside the copper layer.

[0124] (Evaluation of ultrasonic bonding)

[0125] The obtained insulating circuit board (copper-ceramic junction) was subjected to thermal cycling (-50℃×5min←→150℃×5min, 200 cycles).

[0126] For the insulating circuit board after thermal cycling, ultrasonic bonding of copper terminals (10mm × 5mm × 1mm thick) was performed using an ultrasonic metal bonding machine (ULTRASONIC ENGINEERING CO.,LTD.: 60C-904) with a collapse amount of 0.3mm. Furthermore, the copper terminals were bonded in units of 10.

[0127] After bonding, the interface between the copper plate and the ceramic substrate was inspected using an ultrasonic flaw detector (Hitachi Power Solutions Co., Ltd. FineSAT200). Cases with three or more peeling or ceramic cracks out of ten were rated "C", cases with one to two peeling or ceramic cracks out of ten were rated "B", and cases with no peeling or ceramic cracks out of ten were rated "A". The evaluation results are shown in Table 2.

[0128] [Table 1]

[0129]

[0130] *1 Heating rate: Average heating rate within the temperature range above 480℃ and below 650℃

[0131] [Table 2]

[0132]

[0133] In Comparative Example 1, where the amount of Mg at the bonding interface was low, no magnesium oxide layer was formed at the bonding interface, and no active metal oxide phase was present in the copper layer. Furthermore, after thermal cycling, the copper plate peeled off from the ceramic substrate, thus preventing evaluation of ultrasonic bonding performance.

[0134] In Comparative Example 2, where the heating rate was 1°C / min within a temperature range of 480°C to 650°C, no active metal oxide phase was present in the copper layer, and no Cu particles were present in the magnesium oxide layer. Furthermore, the ultrasonic bonding performance after thermal cycling was rated as "C".

[0135] In contrast, in Examples 1 to 9 of the present invention, where a magnesium oxide layer is formed at the bonding interface and an active metal oxide phase composed of oxides of one or more active metals selected from Ti, Zr, Nb, and Hf is dispersed inside the copper layer in contact with the magnesium oxide layer, the bonding reliability under thermal cycling load is also excellent. Subsequently, even if ultrasonic bonding is performed, there is less delamination between the copper plate and the ceramic substrate or less cracking of the ceramic substrate.

[0136] In summary, according to the present invention, it can be confirmed that a copper-ceramic bond, an insulating circuit board, a method for manufacturing a copper-ceramic bond, and a method for manufacturing an insulating circuit board can be provided that can ensure the bonding reliability of the copper component and the ceramic component even under harsh thermal cycling conditions, and can suppress the peeling of the ceramic component and the copper component or the generation of cracks in the ceramic substrate even when ultrasonic bonding is performed.

[0137] Industrial availability

[0138] A copper-ceramic bond, an insulating circuit board, a method for manufacturing a copper-ceramic bond, and a method for manufacturing an insulating circuit board are provided that can ensure the reliability of the bonding between copper and ceramic components even under harsh thermal cycling conditions, and can suppress the peeling of ceramic components from copper components or the generation of cracks in the ceramic substrate even when ultrasonic bonding is performed.

[0139] Symbol Explanation

[0140] 10. Insulating circuit board (copper-ceramic bonding)

[0141] 11. Ceramic substrate (ceramic component)

[0142] 12 circuit layers (copper components)

[0143] 13 metal layers (copper components)

[0144] 41 Magnesium oxide layer

[0145] 42. Contains Cu particles (Cu particles and / or Cu compound particles with active metals)

[0146] 45 copper layers

[0147] 46 active metal oxide phases

Claims

1. A copper-ceramic joint, formed by joining a copper component made of copper or a copper alloy and a ceramic component made of oxygen-containing ceramic, characterized in that, A magnesium oxide layer is formed on the side of the ceramic component between the copper component and the ceramic component. An active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf.

2. The copper-ceramic joint according to claim 1, characterized in that, The thickness of the magnesium oxide layer is in the range of 50 nm or more and 1000 nm or less.

3. The copper-ceramic joint according to claim 1 or 2, characterized in that, Inside the magnesium oxide layer, there are dispersed Cu particles and any one or two of Cu-reactive metal compound particles.

4. The copper-ceramic joint according to claim 3, characterized in that, The Cu particles and the compound particles dispersed inside the magnesium oxide layer have a circular equivalent diameter of more than 10 nm and less than 100 nm.

5. The copper-ceramic joint according to claim 1 or 2, characterized in that, The active metal is Ti.

6. An insulating circuit board, formed by bonding a copper plate made of copper or a copper alloy to the surface of a ceramic substrate made of oxygen-containing ceramic, characterized in that, A magnesium oxide layer is formed on the side of the ceramic substrate between the ceramic substrate and the copper plate. An active metal oxide phase is dispersed inside the copper layer in contact with the magnesium oxide layer. The active metal oxide phase is formed by oxides of one or more active metals selected from Ti, Zr, Nb and Hf.

7. The insulating circuit board according to claim 6, characterized in that, The thickness of the magnesium oxide layer is in the range of 50 nm or more and 1000 nm or less.

8. The insulating circuit board according to claim 6 or 7, characterized in that, Inside the magnesium oxide layer, there are dispersed Cu particles and any one or two of Cu-reactive metal compound particles.

9. The insulating circuit board according to claim 8, characterized in that, The Cu particles and the compound particles dispersed inside the magnesium oxide layer have a circular equivalent diameter of more than 10 nm and less than 100 nm.

10. The insulating circuit board according to claim 6 or 7, characterized in that, The active metal is Ti.

11. A method for manufacturing a copper-ceramic joint, characterized in that, The method for manufacturing the copper-ceramic joint according to any one of claims 1 to 5 comprises: The active metal and Mg preparation step involves preparing one or more active metals and Mg selected from Ti, Zr, Nb and Hf between the copper component and the ceramic component. In the lamination process, the copper component and the ceramic component are laminated using an active metal and Mg; and The bonding process involves bonding the copper component (layered with active metal and Mg) and the ceramic component under pressure along the lamination direction, followed by heat treatment in a vacuum atmosphere. In the preparation process of the active metal and Mg, the amount of active metal is set at 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the Mg content is set at 14 μmol / cm. 2 Above and 180 μmol / cm 2 Within the following range, In the bonding process, the heating rate is set to 5°C / min or higher within the temperature range of 480°C or higher and 650°C or lower, the holding temperature is set to 650°C or higher and 850°C or lower, and the holding time at the holding temperature is set to 10 min or higher and 180 min or lower.

12. A method for manufacturing an insulating circuit board, characterized in that, The manufacturing method is the manufacturing method of the insulating circuit board according to any one of claims 6 to 10, comprising: The active metal and Mg preparation step involves preparing one or more active metals and Mg selected from Ti, Zr, Nb and Hf between the copper plate and the ceramic substrate. In the lamination process, the copper plate and the ceramic substrate are laminated using an active metal and Mg; and The bonding process involves bonding the copper plate (layered with active metal and Mg) and the ceramic substrate under pressure along the lamination direction, followed by heat treatment in a vacuum atmosphere. In the preparation process of the active metal and Mg, the amount of active metal is set at 0.4 μmol / cm³. 2 Above and 47.0 μmol / cm 2 Within the following range, the Mg content is set at 14 μmol / cm. 2 Above and 180 μmol / cm 2 Within the following range, In the bonding process, the heating rate is set to 5°C / min or higher within the temperature range of 480°C or higher and 650°C or lower, the holding temperature is set to 650°C or higher and 850°C or lower, and the holding time at the holding temperature is set to 10 min or higher and 180 min or lower.

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