JP2021031315A - Copper/ceramic joint, insulated circuit board, copper/ceramic joint producing method, insulated circuit board producing method - Google Patents

Abstract

To provide a copper/ceramic joint having an excellent ultrasonic joining property, in which, even when ultrasonic joining is executed, ceramic member and copper member can be suppressed from being peeled off and occurrence of cracking in the ceramic member can be suppressed.SOLUTION: There is provided a Copper/Ceramic joint formed by joining a copper member 12 made of copper or a copper alloy and a ceramic member 11. Cu-Mg intermetallic compound phase 45 composed of an intermetallic compound containing Cu and Mg is formed between the ceramic member 11 and the copper member 12. The area ratio of the Cu-Mg intermetallic compound phase 45 in a region up to 50 μm from the joint surface of the ceramic member 11 to the side of the copper member 12 is within a range of 20% or more and 45% or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a copper / ceramics junction in which a copper member made of copper or a copper alloy and a ceramics member are joined, an insulating circuit board in which a copper plate made of copper or a copper alloy is joined to the surface of the ceramics substrate, and an insulating circuit board. , A method for manufacturing a copper / ceramics joint, and a method for manufacturing an insulated circuit board.

The power module, LED module, and thermoelectric module have a structure in which a power semiconductor element, an LED element, and a thermoelectric element are bonded to an insulating circuit substrate in which a circuit layer made of a conductive material is formed on one surface of the insulating layer. ..
For example, a power semiconductor element for high power control used for controlling a wind power generation, an electric vehicle, a hybrid vehicle, etc. has a large amount of heat generation during operation. An insulated circuit board provided with a circuit layer formed by joining a metal plate having excellent conductivity to one surface of the ceramics substrate has been widely used conventionally. As the insulating circuit board, a circuit board in which a metal plate is joined to the other surface of a ceramics substrate to form a metal layer is also provided.

For example, Patent Document 1 proposes an insulated circuit board in which a circuit layer and a metal layer are formed by joining a copper plate to one surface and the other surface of a ceramic substrate. In Patent Document 1, a copper plate is arranged on one surface and the other surface of a ceramic substrate with an Ag-Cu-Ti brazing material interposed therebetween, and the copper plate is joined by heat treatment (so-called). Active metal brazing method). Since this active metal brazing method uses a brazing material containing Ti, which is an active metal, the wettability between the molten brazing material and the ceramic substrate is improved, and the ceramic substrate and the copper plate are satisfactorily bonded. It will be.

Further, Patent Document 2 proposes an insulating circuit board in which a ceramic substrate and a copper plate are bonded to each other by using a Cu-Mg-Ti brazing material.
In Patent Document 2, the bonding is performed by heating at 560 to 800 ° C. in a nitrogen gas atmosphere, and Mg in the Cu—Mg—Ti alloy is sublimated and does not remain at the bonding interface. Moreover, it is assumed that titanium nitride (TiN) is not substantially formed.

Japanese Patent No. 3211856 Japanese Patent No. 4375730

By the way, in the circuit layer of the above-mentioned insulated circuit board, terminal materials and the like may be ultrasonically bonded.
Here, in the insulated circuit boards described in Patent Documents 1 and 2, when ultrasonic waves are applied to bond terminal materials and the like, cracks occur at the bonding interface and the circuit layer is peeled off. There was a risk. In addition, the ceramic substrate may be cracked.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to suppress peeling between the ceramic member and the copper member even when ultrasonic bonding is performed, and the occurrence of cracking of the ceramic member is caused. It is an object of the present invention to provide a copper / ceramics bonded body, an insulating circuit board, a method for manufacturing a copper / ceramics bonded body, and a method for manufacturing an insulated circuit board, which can be suppressed and have excellent ultrasonic bonding properties.

In order to solve the above-mentioned problems, the copper / ceramics joint of the present invention is a copper / ceramics joint in which a copper member made of copper or a copper alloy and a ceramics member are bonded to each other. A Cu-Mg metal-to-metal compound phase composed of a metal-to-metal compound containing Cu and Mg is formed between the copper member and the copper member, and the region from the joint surface of the ceramic member to the copper member side up to 50 μm is described. The area ratio of the Cu-Mg metal-to-metal compound phase is in the range of 20% or more and 45% or less.

According to the copper / ceramics bonded body of the present invention, the area ratio of the Cu-Mg metal-to-metal compound phase in the region from the bonding surface of the ceramics member to the copper member side up to 50 μm is within the range of 20% or more and 45% or less. Therefore, the bonding interface is appropriately strengthened, and even when an ultrasonic wave is applied, peeling between the ceramic member and the copper member can be suppressed, and cracking of the ceramic member is suppressed. It is possible to improve ultrasonic bonding.

Here, in the copper / ceramics joint of the present invention, it is preferable that at least a part of the Cu-Mg intermetallic compound phase is in contact with the ceramics member.
In this case, by contacting at least a part of the relatively hard Cu-Mg intermetallic compound phase with the ceramic member, it is possible to suppress stress concentration on the ceramic member during ultrasonic bonding, and further suppress cracking of the ceramic member. Is possible.

Further, in the copper / ceramics bonded body of the present invention, it is preferable that Cu particles are dispersed inside the Cu-Mg intermetallic compound phase.
In this case, the Cu particles described above improve the strength of the Cu-Mg intermetallic compound phase, and it is possible to further suppress the peeling between the ceramic member and the copper member when an ultrasonic wave is applied.

The insulating circuit board of the present invention is an insulating circuit board in which a copper plate made of copper or a copper alloy is bonded to the surface of a ceramics substrate, and Cu and Mg are contained between the ceramics substrate and the copper plate. A Cu-Mg metal-to-metal compound phase composed of an inter-metal compound is formed, and the area ratio of the Cu-Mg metal-to-metal compound phase in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm is 20% or more and 45. It is characterized by being within the range of% or less.

According to the insulating circuit board of the present invention, the area ratio of the Cu-Mg metal-to-metal compound phase in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm is within the range of 20% or more and 45% or less. Therefore, the bonding interface is appropriately strengthened, and even when an ultrasonic wave is applied, the peeling between the ceramic substrate and the copper plate can be suppressed, and the occurrence of cracks in the ceramic substrate can be suppressed, and the ultrasonic wave can be suppressed. It is possible to improve the bondability.

Here, in the insulating circuit board of the present invention, it is preferable that at least a part of the Cu-Mg intermetallic compound phase is in contact with the ceramic substrate.
In this case, by contacting at least a part of the relatively hard Cu-Mg intermetallic compound phase with the ceramic substrate, it is possible to suppress stress concentration on the ceramic substrate during ultrasonic bonding, and further suppress cracking of the ceramic substrate. Is possible.

Further, in the insulating circuit board of the present invention, it is preferable that Cu particles are dispersed inside the Cu-Mg intermetallic compound phase.
In this case, the Cu particles described above improve the strength of the Cu-Mg intermetallic compound phase, and it is possible to further suppress the peeling between the ceramic substrate and the copper plate when an ultrasonic wave is applied.

The method for producing a copper / ceramics joint of the present invention is a method for producing a copper / ceramics joint for producing the above-mentioned copper / ceramics joint, in which Mg is arranged between the copper member and the ceramics member. The Mg placement step, the laminating step of laminating the copper member and the ceramic member via Mg, and the state where the copper member and the ceramic member laminated via Mg are pressurized in the laminating direction. It includes a joining step of heat-treating and joining in a vacuum atmosphere. In the Mg placement step, the amount of Mg is set ^{within the range of 0.69 mg / cm 2} or more and 4.35 mg / cm ² or less, and the joining step is performed. In the above, the temperature rise rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is set to 5 ° C./min or higher, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer.

According to the method for producing a copper / ceramics conjugate having this configuration, the amount of Mg in the Mg placement step is ^{within the range of 0.69 mg / cm 2} or more and 4.35 mg / cm ² or less, which is necessary for the interfacial reaction. A sufficient liquid phase can be obtained. Therefore, the copper member and the ceramic member can be reliably joined.
In the joining step, the rate of temperature rise in the temperature range of 480 ° C. or higher and lower than 650 ° C. is set to 5 ° C./min or higher, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer, which is necessary for the interfacial reaction. The liquid phase can be maintained for a certain period of time or longer, and a uniform interfacial reaction is promoted. As a result, a Cu-Mg intermetallic compound phase is formed at the bonding interface, and the area ratio of the Cu-Mg intermetallic compound phase in the region from the bonding surface of the ceramic member to the copper member side up to 50 μm is 20% or more and 45. It can be within the range of% or less.

The method for manufacturing an insulated circuit board of the present invention is a method for manufacturing an insulated circuit board for manufacturing the above-mentioned insulated circuit board, wherein Mg is placed between the copper plate and the ceramics substrate, and the Mg placement step is described. A laminating step of laminating a copper plate and the ceramics substrate via Mg, and a state in which the copper plate and the ceramics substrate laminated via Mg are pressurized in the laminating direction and heat-treated in a vacuum atmosphere to join them. In the Mg placement step, the amount of Mg is set in ^{the range of 0.69 mg / cm 2} or more and 4.35 mg / cm ² or less, and in the joining step, the temperature is 480 ° C or more and less than 650 ° C. The temperature rise rate in the temperature range is set to 5 ° C./min or more, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer.

According to the method for manufacturing an insulated circuit board having this configuration, in the Mg placement step, the amount of Mg is set in ^{the range of 0.69 mg / cm 2} or more and 4.35 mg / cm ² or less, so that the liquid phase required for the interfacial reaction Can be sufficiently obtained. Therefore, the copper plate and the ceramic substrate can be reliably joined.
In the joining step, the rate of temperature rise in the temperature range of 480 ° C. or higher and lower than 650 ° C. is set to 5 ° C./min or higher, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer, which is necessary for the interfacial reaction. The liquid phase can be maintained for a certain period of time or longer, and a uniform interfacial reaction is promoted. As a result, a Cu-Mg intermetallic compound phase is formed at the bonding interface, and the area ratio of the Cu-Mg intermetallic compound phase in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm is 20% or more and 45%. It can be within the following range.

According to the present invention, even when ultrasonic bonding is performed, peeling between the ceramic member and the copper member can be suppressed, and cracking of the ceramic member can be suppressed, resulting in ultrasonic bonding. It is possible to provide an excellent copper / ceramics bonded body, an insulated circuit board, a method for manufacturing a copper / ceramics bonded body, and a method for manufacturing an insulated circuit board.

It is the schematic explanatory drawing of the power module using the insulation circuit board which concerns on embodiment of this invention. It is an observation photograph of the bonding interface between the circuit layer (metal layer) of the insulating circuit board and the ceramics substrate which concerns on embodiment of this invention. It is a flow chart of the manufacturing method of the insulation circuit board which concerns on embodiment of this invention. It is the schematic explanatory drawing of the manufacturing method of the insulation circuit board which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The copper / ceramics joint according to the present embodiment includes a ceramics substrate 11 as a ceramics member made of ceramics, and 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. Is an insulated circuit board 10 formed by joining. FIG. 1 shows a power module 1 provided with an insulated circuit board 10 according to the present embodiment.

The power module 1 is a semiconductor element 3 bonded to an insulating circuit board 10 on which a circuit layer 12 and a metal layer 13 are arranged and one surface (upper surface in FIG. 1) of the circuit layer 12 via a bonding layer 2. And a heat sink 30 arranged on the other side (lower side in FIG. 1) of the metal layer 13.

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

The heat sink 30 is for dissipating heat from the above-mentioned insulating circuit board 10. The heat sink 30 is made of copper or a copper alloy, and in this embodiment, it is made of phosphorylated copper. The heat sink 30 is provided with a flow path 31 for flowing a cooling fluid.
In this embodiment, the heat sink 30 and the metal layer 13 are joined by a solder layer 32 made of a solder material. The solder layer 32 is made of, for example, a Sn-Ag-based, Sn-In-based, or Sn-Ag-Cu-based solder material.

As shown in FIG. 1, the insulating circuit board 10 of the present embodiment includes a ceramic substrate 11, a circuit layer 12 disposed on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and ceramics. It includes a metal layer 13 disposed on the other surface (lower surface in FIG. 1) of the substrate 11.

The ceramic substrate 11 is made of ceramics such as silicon nitride (Si ₃ N ₄ ), aluminum nitride (Al _{N), and alumina (Al 2} O ₃ ), which are excellent in insulating properties and heat dissipation. In the present embodiment, the ceramic substrate 11 is made of aluminum nitride (AlN), which has particularly excellent heat dissipation. Further, the thickness of the ceramic substrate 11 is set within the range of, for example, 0.2 mm or more and 1.5 mm or less, and in the present embodiment, it is set to 0.635 mm.

As shown in FIG. 4, the circuit layer 12 is formed by joining a copper plate 22 made of copper or a copper alloy to one surface (upper surface in FIG. 4) of the ceramic substrate 11.
In the present embodiment, the circuit layer 12 is formed by joining a copper plate 22 made of a rolled plate of oxygen-free copper to a ceramic substrate 11.
The thickness of the copper plate 22 to be the circuit layer 12 is set within the range of 0.1 mm or more and 2.0 mm or less, and in this embodiment, it is set to 0.6 mm.

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 (lower surface in FIG. 4) of the ceramic substrate 11.
In the present embodiment, the metal layer 13 is formed by joining a copper plate 23 made of a rolled plate of oxygen-free copper to a ceramic substrate 11.
The thickness of the copper plate 23 to be the metal layer 13 is set within the range of 0.1 mm or more and 2.0 mm or less, and in this embodiment, it is set to 0.6 mm.

Then, at the bonding interface between the ceramic substrate 11 and the circuit layer 12 (metal layer 13), as shown in FIG. 2, a Cu-Mg intermetallic compound phase 45 composed of an intermetallic compound containing Cu and Mg is formed. There is.
The area ratio of the Cu-Mg intermetallic compound phase 45 in the region from the bonding surface of the ceramic substrate 11 to the circuit layer 12 (metal layer 13) side up to 50 μm is within the range of 20% or more and 45% or less. By defining the area ratio of the Cu-Mg intermetallic compound phase 45 in this way, the bonding interface is appropriately strengthened, and the ultrasonic bonding property of the insulating circuit board 11 is improved.
In order to further improve the ultrasonic bonding property of the insulating circuit board 11, the lower limit of the area ratio of the above-mentioned Cu-Mg intermetallic compound phase 45 is preferably 22% or more, preferably 28% or more. Is even more preferable. On the other hand, the upper limit of the area ratio of the above-mentioned Cu-Mg intermetallic compound phase 45 is preferably 40% or less, and more preferably 32% or less.

Here, in the present embodiment, as shown in FIG. 2, it is preferable that at least a part of the Cu-Mg intermetallic compound phase 45 is in contact with the ceramic substrate 11.

Further, in the present embodiment, as shown in FIG. 2, it is preferable that the Cu particles 46 are dispersed inside the Cu-Mg intermetallic compound phase 45. The Cu particles 46 are composed of a simple substance of Cu and a solid solution of Cu in which Mg or the like is dissolved in Cu.

Here, in FIG. 2, the one-step recessed region is the Cu-Mg intermetallic compound phase 45, and the granular region existing inside the recessed region (Cu-Mg intermetallic compound phase 45) is the Cu particles 46. is there. Further, the area ratio of the Cu-Mg intermetallic compound layer 45 is the area ratio of the recessed region in FIG. 2, and does not include the region of the Cu particles 46 existing inside (the portion shining white in the electronic image). ..

Hereinafter, a method for manufacturing the insulated circuit board 10 according to the present embodiment will be described with reference to FIGS. 3 and 4.

(Mg placement step S01)
First, a ceramic substrate 11 made of aluminum nitride (AlN) is prepared, and as shown in FIG. 4, between the copper plate 22 as the circuit layer 12 and the ceramic substrate 11, and between the copper plate 23 as the metal layer 13 and the ceramic substrate. Mg is arranged between 11 and 11, respectively.
In the present embodiment, the Mg foil 25 is arranged between the copper plate 22 serving as the circuit layer 12 and the ceramic substrate 11 and between the copper plate 23 serving as the metal layer 13 and the ceramic substrate 11.

Here, in the Mg placement step S01, the amount of Mg to be placed is set within the range of ^{0.69 mg / cm 2} or more and 4.35 mg / cm ^{2 or less.}
The lower limit of the Mg content to be placed is preferably set to 1.04 mg / cm ² or more, and even more preferably from 1.39 mg / cm ² or more. On the other hand, the upper limit of the Mg content to be placed is preferably set to 3.48 mg / cm ² or less, and even more preferably from 3.13 mg / cm ² or less.

(Laminating step S02)
Next, the copper plate 22 and the ceramic substrate 11 are laminated via the Mg foil 25, and the ceramic substrate 11 and the copper plate 23 are laminated via the Mg foil 25.

(Joining step S03)
Next, the laminated copper plate 22, Mg foil 25, ceramic substrate 11, Mg foil 25, and copper plate 23 are pressurized in the laminating direction, charged into a vacuum furnace, and heated to form the copper plate 22 and the ceramic substrate 11. The copper plate 23 is joined.
Here, the heat treatment conditions in the joining step S03 are such that the heating rate in the temperature region of 480 ° C. or higher and lower than 650 ° C. is 5 ° C./min or higher, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer. By defining the heat treatment conditions in this way, the Cu—Mg liquid phase required for the interfacial reaction can be secured, and a uniform interfacial reaction can proceed. As a result, the Cu-Mg intermetallic compound phase 45 is formed at the bonding interface of the ceramic substrate 11. The area ratio of the Cu-Mg intermetallic compound phase 45 in the region from the bonding surface of the ceramic substrate 11 to the circuit layer 12 (metal layer 13) side up to 50 μm is within the range of 20% or more and 45% or less.

The lower limit of the temperature rising rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is preferably 7 ° C./min or higher, and more preferably 9 ° C./min or higher. On the other hand, the upper limit of the temperature rising rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is not particularly limited, but is preferably 15 ° C./min or less, and more preferably 12 ° C./min or less.
Further, the lower limit of the holding temperature is preferably 680 ° C. or higher, and more preferably 700 ° C. or higher. On the other hand, the upper limit of the holding temperature is not particularly limited, but is preferably 800 ° C. or lower, and more preferably 750 ° C. or lower.
Further, the lower limit of the holding time is preferably 45 min or more, and more preferably 60 min or more. On the other hand, the upper limit of the holding time is not particularly limited, but is preferably 120 min or less, and more preferably 90 min or less.

The pressurizing load in the joining step S03 is preferably in the range of 0.049 MPa or more and 3.4 MPa or less.
Further, the degree of vacuum in the joining step S03 is preferably in the range of ^{1 × 10 −6} Pa or more and 5 × 10 − ^{2 Pa or less.}

As described above, the insulating circuit board 10 according to the present embodiment is manufactured by the Mg placement step S01, the lamination step S02, and the joining step S03.

(Heat sink joining step S04)
Next, the heat sink 30 is joined to the other surface side of the metal layer 13 of the insulating circuit board 10.
The insulating circuit board 10 and the heat sink 30 are laminated via a solder material and charged into a heating furnace, and the insulating circuit board 10 and the heat sink 30 are solder-bonded via the solder layer 32.

(Semiconductor element joining step S05)
Next, the semiconductor element 3 is soldered to one surface of the circuit layer 12 of the insulating circuit board 10.
The power module 1 shown in FIG. 1 is produced by the above-mentioned steps.

According to the insulating circuit board 10 (copper / ceramics bonded body) of the present embodiment having the above configuration, between Cu and Mg metals at the bonding interface between the circuit layer 12 (and the metal layer 13) and the ceramics substrate 11. The compound phase 45 is formed, and the area ratio of the Cu-Mg metal-to-metal compound phase 45 in the region from the bonding surface of the ceramic substrate 11 to the circuit layer 12 (and the metal layer 13) side up to 50 μm is 20% or more and 45% or less. Since it is within the range of, the bonding interface is appropriately strengthened, and even when an ultrasonic wave is applied, peeling between the ceramic substrate 11 and the circuit layer 12 (and the metal layer 13) can be suppressed. At the same time, it is possible to suppress the occurrence of cracks in the ceramic substrate 11 and improve the ultrasonic bondability.

Further, in the present embodiment, when at least a part of the Cu-Mg intermetallic compound phase 45 is in contact with the ceramic substrate 11, it is possible to suppress the concentration of stress on the ceramic substrate 11 at the time of ultrasonic bonding, and the ceramics. It is possible to further suppress cracking of the substrate 11.

Further, in the present embodiment, when the Cu particles 46 are dispersed inside the Cu-Mg intermetallic compound phase 45, the Cu particles 46 improve the strength of the Cu-Mg intermetallic compound phase 45. It is possible to further suppress the peeling between the ceramic substrate 11 and the circuit layer 12 (and the metal layer 13) when an ultrasonic wave is applied.

According to the method for manufacturing an insulated circuit board according to the present embodiment, the amount of Mg is set in ^{the range of 0.69 mg / cm 2} or more and 4.35 mg / cm ² or less in the Mg arrangement step S01, which is necessary for the interfacial reaction. A sufficient liquid phase can be obtained. Therefore, the circuit layer 12, the metal layer 13, and the ceramic substrate 11 can be reliably joined.
Then, in the joining step S02, the temperature rising rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is set to 5 ° C./min or higher, and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer, which is necessary for the interfacial reaction. The liquid phase can be maintained for a certain period of time or longer, and a uniform interfacial reaction is promoted. As a result, the Cu-Mg intermetallic compound phase 45 can be formed at the bonding interface, and between Cu-Mg metals in a region up to 50 μm from the bonding surface of the ceramic substrate 11 to the circuit layer 12 (and metal layer 13) side. The area ratio of the compound phase 45 can be in the range of 20% or more and 45% or less.

In this embodiment, as described above, Ti, Zr, Nb, and Hf are not used for joining, so that Ti, Zr, Nb, and Hf are nitrided in the vicinity of the joining surface of the ceramic substrate 11 (ceramic member). Insulated circuit board 10 (copper / ceramics) capable of suppressing cracking of the ceramic substrate 11 (ceramic member) during high-temperature operation without the physical phase or the intermetallic compound phase containing Ti, Zr, Nb, and Hf. Joined body) can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the invention.
For example, in the present embodiment, a semiconductor element is mounted on an insulating circuit board to form a power module, but the present embodiment is not limited to this. For example, an LED element may be mounted on a circuit layer of an insulated circuit board to form an LED module, or a thermoelectric element may be mounted on a circuit layer of an insulated circuit board to form a thermoelectric module.

Further, in the insulated circuit board of the present embodiment, it has been described that the circuit layer and the metal layer are both composed of a copper plate made of copper or a copper alloy, but the present invention is not limited to this.
For example, if the circuit layer and the ceramic substrate are composed of the copper / ceramics joint of the present invention, the material and joining method of the metal layer are not limited, and the metal layer may not be present, or the metal layer may be aluminum or It may be composed of an aluminum alloy or a laminate of copper and aluminum.
On the other hand, as long as the metal layer and the ceramic substrate are made of the copper / ceramics joint of the present invention, the material and joining method of the circuit layer are not limited, and the circuit layer may be made of aluminum or an aluminum alloy. , It may be composed of a laminate of copper and aluminum.

Further, in the present embodiment, the configuration is described in which Mg foil is laminated between the copper plate and the ceramic substrate, but the present invention is not limited to this, and a thin film made of Mg is formed on the joint surface between the ceramic substrate and the copper plate. , The film may be formed by a sputtering method, a vapor deposition method, or the like.

Further, in the insulating circuit board of the present embodiment, a ceramic substrate made of aluminum nitride (AlN) has been described as an example, but the present invention is not limited to this, and alumina (Al ₂ O ₃ ) is used. , Silicon nitride (Si ₃ N ₄ ) or the like may be used.

The results of the confirmation experiment conducted to confirm the effect of the present invention will be described below.

First, the ceramic substrate (40 mm × 40 mm) shown in Table 1 was prepared. The thickness of Al N _{and Al 2} O ₃ was 0.635 mm, and that of Si _{3 N 4} was 0.32 mm.
A copper plate (37 mm × 37 mm × thickness 0.3 mm) made of oxygen-free copper was bonded to both sides of this ceramic substrate under the conditions shown in Table 1 to obtain an insulating circuit substrate (copper / ceramics bonded body). The degree of vacuum of the vacuum furnace at the time of joining was set to 6 × 10 ^-3 Pa.

Regarding the obtained insulating circuit board (copper / ceramics joint), the area ratio of the Cu-Mg intermetallic compound phase in the region from the joint surface of the ceramics substrate to the copper plate side up to 50 μm, the presence or absence of contact with the ceramics substrate, Cu- The presence or absence of Cu particles in the Mg intermetallic compound phase, the initial bonding ratio, and the ultrasonic bonding property were evaluated as follows.

(Cu-Mg intermetallic compound phase)
An observation sample was taken from the central part of the obtained insulating circuit substrate (copper / ceramics junction), and the junction interface between the copper plate and the ceramics substrate was measured using an electron beam microanalyzer (JXA-8339F manufactured by Nippon Denshi Co., Ltd.). Obtained the elemental MAP of Mg in the region including the junction interface (400 μm × 600 μm) under the conditions of magnification 2000 times and acceleration voltage 15 kV, and Cu was averaged at 5 points in the quantitative analysis in the region where the presence of Mg was confirmed. A region in which the concentration was 5 atomic% or more and the Mg concentration was 30 atoms or more and 70 atomic% or less was defined as the Cu-Mg metal-to-metal compound phase. Then, the area ratio of the intermetallic compound phase in the region from the joint surface of the ceramic substrate to the copper plate side up to 50 μm was calculated. The number of observation fields was 5, and the average value thereof is shown in Table 2.
The area ratio was calculated by observing a total of five measurement points, the region of the center point of the insulated circuit board and the region of four vertices of a 20 mm × 20 mm quadrangle centered on that point.

Further, the contact ratio between the Cu-Mg intermetallic compound phase and the ceramic substrate (the ratio of the contact length between the Cu-Mg intermetallic compound phase and the ceramic substrate to the measurement viewing width) was calculated.
Further, inside the Cu-Mg intermetallic compound phase, the region where only Cu or Cu and Mg coexist was determined to be Cu particles, and the presence or absence of Cu-containing particles was determined.

(Initial bonding rate)
The bonding ratio between the copper plate and the ceramic substrate was evaluated. Specifically, in an insulated circuit board, the bonding ratio at the interface between the copper plate and the ceramic substrate was evaluated using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Power Solutions, Ltd.) and calculated from the following formula. Here, the initial bonding area is the area to be bonded before bonding, that is, the area of the circuit layer. In the image obtained by binarizing the ultrasonic flaw detection image, the peeling is shown by the white part in the joint, and the area of this white part is defined as the peeling area.
(Joining ratio) = {(Initial joining area)-(Non-joining area)} / (Initial joining area) x 100

(Ultrasonic bonding)
Using an ultrasonic metal bonding machine (manufactured by Ultrasonic Industry Co., Ltd .: 60C-904) with respect to the obtained insulated circuit board, copper terminals (10 mm × 5 mm × 1 mm thickness) were provided under the condition of a coplus amount of 0.3 mm. Ultrasonic bonding. In addition, 10 copper terminals were joined to each.
After joining, the bonding interface between the copper plate and the ceramic substrate was inspected using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Solutions, Ltd.). "X" indicates that 3 or more of the 10 pieces have peeled or cracked ceramics, and "△" indicates that 1 or more and 2 or less of the 10 pieces have cracked ceramics. Alternatively, those in which no ceramic cracks were observed were evaluated as "○". The evaluation results are shown in Table 2.

In Comparative Example 1 in which the heating rate in the temperature region of 480 ° C. or higher and lower than 650 ° C. was 2 ° C./min in the bonding step, the Cu-Mg intermetallic compound in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm. The area ratio of the phase was 12.8%, which was lower than the range of the present invention, and the ultrasonic bondability was "x".
In Comparative Example 2 in which the amount of Mg was 5.21 mg / cm ² in the Mg arrangement step, the area ratio of the Cu-Mg intermetallic compound phase in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm was 50.2. %, Which is higher than the range of the present invention, has vertical cracks, and has an ultrasonic bondability of "x". In addition, the initial bonding rate was as low as 80.7%.

On the other hand, in Example 1-8 of the present invention, the area ratio of the Cu-Mg intermetallic compound phase in the region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm is within the range of 20% or more and 45% or less. The initial bonding rate was high, and even when ultrasonic bonding was performed, there was little peeling between the copper plate and the ceramic substrate and cracking of the ceramic substrate, and the ultrasonic bonding property was excellent.

As a result, according to the example of the present invention, it is possible to suppress the peeling of the ceramic member and the copper member and to suppress the occurrence of cracking of the ceramic member even when ultrasonic bonding is performed. It was confirmed that it is possible to provide a copper / ceramics bond, an insulating circuit board, a method for manufacturing a copper / ceramics bond, and a method for manufacturing an insulated circuit board, which are excellent in ultrasonic bonding.

10 Insulated circuit board (copper / ceramic joint)
11 Ceramic substrate (ceramic member)
12 Circuit layer (copper member)
13 Metal layer (copper member)
45 Cu-Mg Intermetallic Compound Phase 46 Cu Particles

Claims (8)

A copper / ceramic joint formed by joining a copper member made of copper or a copper alloy and a ceramic member.
A Cu-Mg intermetallic compound phase composed of an intermetallic compound containing Cu and Mg is formed between the ceramic member and the copper member.
Copper / ceramics characterized in that the area ratio of the Cu-Mg intermetallic compound phase in the region from the joint surface of the ceramic member to the copper member side up to 50 μm is within the range of 20% or more and 45% or less. Joined body. The copper / ceramics conjugate according to claim 1, wherein at least a part of the Cu-Mg intermetallic compound phase is in contact with the ceramics member. The copper / ceramics conjugate according to claim 1 or 2, wherein Cu particles are dispersed inside the Cu-Mg intermetallic compound phase. An insulating circuit board in which a copper plate made of copper or a copper alloy is bonded to the surface of a ceramic substrate.
A Cu-Mg intermetallic compound phase composed of an intermetallic compound containing Cu and Mg is formed between the ceramic substrate and the copper plate.
An insulating circuit board characterized in that the area ratio of the Cu-Mg intermetallic compound phase in a region from the bonding surface of the ceramic substrate to the copper plate side up to 50 μm is within the range of 20% or more and 45% or less. The insulating circuit board according to claim 4, wherein at least a part of the Cu-Mg intermetallic compound phase is in contact with the ceramic substrate. The insulating circuit board according to claim 4 or 5, wherein Cu particles are dispersed inside the Cu-Mg intermetallic compound phase. A method for manufacturing a copper / ceramics joint according to any one of claims 1 to 3, wherein the copper / ceramics joint is manufactured.
The Mg placement step of placing Mg between the copper member and the ceramic member,
A laminating step of laminating the copper member and the ceramic member via Mg, and
A joining step in which the copper member and the ceramic member laminated via Mg are joined by heat treatment in a vacuum atmosphere while being pressurized in the stacking direction.
Is equipped with
In the Mg placement step, the amount of Mg is set within the range of ^{0.69 mg / cm 2} or more and 4.35 mg / cm ^{2 or less.}
In the bonding step, the copper / ceramics bonded body is characterized in that the temperature rising rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is 5 ° C./min or higher and the temperature is maintained at 650 ° C. or higher for 30 minutes or longer. Manufacturing method. The method for manufacturing an insulated circuit board according to any one of claims 4 to 6.
The Mg placement step of placing Mg between the copper plate and the ceramic substrate,
A laminating step of laminating the copper plate and the ceramic substrate via Mg, and
A joining process in which the copper plate laminated via Mg and the ceramic substrate are joined by heat treatment in a vacuum atmosphere while being pressurized in the stacking direction.
Is equipped with
In the Mg placement step, the amount of Mg is set within the range of ^{0.69 mg / cm 2} or more and 4.35 mg / cm ^{2 or less.}
In the joining step, the temperature rise rate in the temperature range of 480 ° C. or higher and lower than 650 ° C. is set to 5 ° C./min or higher, and the insulating circuit board is maintained at a temperature of 650 ° C. or higher for 30 minutes or longer. Method.