阅读说明：本技术 铜-陶瓷接合体、绝缘电路基板及铜-陶瓷接合体的制造方法、绝缘电路基板的制造方法 (Copper-ceramic joined body, insulated circuit board, method for producing copper-ceramic joined body, and method for producing insulated circuit board ) 是由 寺崎伸幸 于 2019-01-16 设计创作，主要内容包括：本发明的铜-陶瓷接合体接合由铜或铜合金构成的铜部件(12)及由铝氧化物构成的陶瓷部件(11)而成,在铜部件(12)与陶瓷部件(11)之间,在陶瓷部件(11)侧形成有氧化镁层(31),在该氧化镁层(31)与铜部件(12)之间形成有在Cu的母相中固溶有Mg的Mg固溶层(32),在Mg固溶层(32)存在选自Ti、Zr、Nb、Hf的一种或两种以上的活性金属。(A copper-ceramic joined body comprising a copper member (12) made of copper or a copper alloy and a ceramic member (11) made of aluminum oxide joined together, wherein a magnesium oxide layer (31) is formed between the copper member (12) and the ceramic member (11) on the ceramic member (11) side, a Mg solid solution layer (32) in which Mg is solid-dissolved in a parent phase of Cu is formed between the magnesium oxide layer (31) and the copper member (12), and one or more active metals selected from Ti, Zr, Nb, and Hf are present in the Mg solid solution layer (32).)

1. A copper-ceramic joined body obtained by joining a copper member made of copper or a copper alloy and a ceramic member made of aluminum oxide,

a magnesium oxide layer formed between the copper member and the ceramic member on the ceramic member side, and a Mg solid solution layer formed between the magnesium oxide layer and the copper member, the Mg solid solution layer being formed by dissolving Mg in a Cu matrix phase,

one or more active metals selected from Ti, Zr, Nb and Hf are present in the Mg solid solution layer.

2. The copper-ceramic junction body according to claim 1,

an intermetallic compound phase containing Cu and the active metal is dispersed in the Mg solid solution layer.

3. The copper-ceramic junction body according to claim 1 or 2,

cu particles are dispersed in the magnesium oxide layer.

4. The copper-ceramic junction body according to any one of claims 1 to 3,

an area ratio of a Cu-Mg intermetallic compound phase in a region between the ceramic member and the copper member, the region being 50 μm from a joining surface of the ceramic member toward the copper member side, is set to 15% or less.

5. The copper-ceramic junction body according to any one of claims 1 to 4,

the thickness of the magnesium oxide layer is set to be in the range of 50nm to 1000 nm.

6. An insulated circuit board comprising a ceramic substrate made of aluminum oxide and a copper plate made of copper or a copper alloy bonded to a surface of the ceramic substrate,

a magnesium oxide layer is formed between the copper plate and the ceramic substrate and on the ceramic substrate side, and a Mg solid solution layer in which Mg is solid-dissolved in a parent phase of Cu is formed between the magnesium oxide layer and the copper plate,

one or more active metals selected from Ti, Zr, Nb and Hf are present in the Mg solid solution layer.

7. The insulated circuit substrate of claim 6,

an intermetallic compound phase containing Cu and the active metal is dispersed in the Mg solid solution layer.

8. The insulated circuit substrate of claim 6 or 7,

cu particles are dispersed in the magnesium oxide layer.

9. The insulated circuit substrate of any one of claims 6 to 8,

an area ratio of a Cu-Mg intermetallic compound phase in a region between the ceramic substrate and the copper plate, the region extending from a bonding surface of the ceramic substrate to the copper plate side by 50 μm, is set to 15% or less.

10. The insulated circuit substrate of any one of claims 6 to 9,

the thickness of the magnesium oxide layer is set to be in the range of 50nm to 1000 nm.

11. A method for producing a copper-ceramic joined body according to any one of claims 1 to 5, the method comprising:

an active metal and Mg disposing step of disposing one or two or more active metal simple substances selected from Ti, Zr, Nb, and Hf and a Mg simple substance between the copper member and the ceramic member;

a lamination step of laminating the copper member and the ceramic member via an active metal and Mg; and

a joining step of joining the copper member and the ceramic member laminated via the active metal and Mg in a lamination direction by applying a heat treatment in a vacuum atmosphere while pressing the copper member and the ceramic member in the lamination direction,

in the step of preparing the active metal and Mg, the amount of the active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

12. The method of producing a copper-ceramic joined body according to claim 11,

the pressure load in the bonding step is set to be in the range of 0.049MPa to 3.4MPa,

the heating temperature in the bonding step is set in a range of 500 ℃ to 850 ℃ when Cu and Mg are laminated in a contact state, and in a range of 670 ℃ to 850 ℃ when Cu and Mg are laminated in a non-contact state.

13. A method for manufacturing an insulated circuit board, the method for manufacturing an insulated circuit board according to any one of claims 6 to 10, comprising:

an active metal and Mg disposing step of disposing a simple substance of one or two or more active metals selected from Ti, Zr, Nb, and Hf and a simple substance of Mg between the copper plate and the ceramic substrate;

a lamination step of laminating the copper plate and the ceramic substrate via an active metal and Mg; and

a bonding step of bonding the copper plate and the ceramic substrate laminated via the active metal and Mg in a lamination direction by performing a heat treatment in a vacuum atmosphere while pressing the copper plate and the ceramic substrate in the lamination direction,

in the step of preparing the active metal and Mg, the amount of the active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

14. The method of manufacturing an insulated circuit substrate according to claim 13,

the pressure load in the bonding step is set to be in the range of 0.049MPa to 3.4MPa,

the heating temperature in the bonding step is set in a range of 500 ℃ to 850 ℃ when Cu and Mg are laminated in a contact state, and in a range of 670 ℃ to 850 ℃ when Cu and Mg are laminated in a non-contact state.

Technical Field

The present invention relates to a copper-ceramic joined body obtained by joining a copper member made of copper or a copper alloy and a ceramic member made of aluminum oxide, an insulated circuit board, a method for producing the copper-ceramic joined body, and a method for producing the insulated circuit board.

The present application claims priority based on patent application No. 2018-010965 filed in japanese application No. 2018-25/1 and patent application No. 2018-227472 filed in japanese application No. 2018-4/12/4, and the contents thereof are incorporated herein by reference.

Background

In the power module, the LED module, and the thermoelectric module, a power semiconductor element, an LED element, and a thermoelectric element are bonded to an insulating circuit board in which a circuit layer made of a conductive material is formed on one surface of an insulating layer.

Since a power semiconductor device for controlling high power such as a wind power generator, an electric vehicle, and a hybrid vehicle generates a large amount of heat during operation, for example, an insulated circuit board including a ceramic substrate made of aluminum oxide or the like and a circuit layer formed by bonding a metal plate having excellent conductivity to one surface of the ceramic substrate has been widely used as a substrate on which the power semiconductor device is mounted. As an insulated circuit board, a board in which a metal layer is formed by bonding a metal plate to the other surface of a ceramic board is also provided.

For example, patent document 1 proposes an insulated circuit board having: the first metal plate and the second metal plate constituting the circuit layer and the metal layer were made into copper plates, and the copper plates were directly bonded to the ceramic substrate by the DBC method. In this DBC method, a liquid phase is generated at an interface between the copper plate and the ceramic substrate by utilizing a eutectic reaction between copper and a copper oxide, thereby bonding the copper plate and the ceramic substrate.

Further, patent document 2 proposes an insulated circuit board having: a circuit layer and a metal layer are formed on one surface and the other surface of a ceramic substrate by bonding copper plates. In this power module substrate, a copper plate is disposed with an Ag — Cu — Ti based brazing material interposed between one surface and the other surface of a ceramic substrate, and the copper plate is joined by heat treatment (so-called active metal brazing method). In this active metal brazing method, since a brazing material containing Ti as an active metal is used, the wettability of the molten brazing material with the ceramic substrate is improved, and the ceramic substrate and the copper plate are well joined.

Patent document 3 proposes a slurry including: a brazing filler metal for bonding a copper plate and a ceramic substrate in a high-temperature nitrogen atmosphere contains a powder made of a Cu-Mg-Ti alloy. In patent document 3, the Cu — Mg — Ti alloy is heated at 560 to 800 ℃ in a nitrogen atmosphere to bond the Cu — Mg — Ti alloy, and Mg in the Cu — Mg — Ti alloy is sublimated, so that the Mg does not remain in the bonding interface, and titanium nitride (TiN) is not substantially formed.

Patent document 1: japanese patent laid-open publication No. H04-162756

Patent document 2: japanese patent No. 3211856

Patent document 3: japanese patent No. 4375730

However, as disclosed in patent document 1, when the ceramic substrate and the copper plate are bonded by the DBC method, the bonding temperature needs to be 1065 ℃ or higher (the eutectic temperature between copper and copper oxide or higher), and thus there is a possibility that the ceramic substrate may be deteriorated during bonding.

Further, as disclosed in patent document 2, when a ceramic substrate and a copper plate are joined by an active metal brazing method, the brazing material contains Ag, and Ag exists at the joining interface, so that migration is likely to occur, and it cannot be used for high withstand voltage applications. Further, since the bonding temperature is 900 ℃ which is a relatively high temperature, there is still a problem of deterioration of the ceramic substrate.

Further, as disclosed in patent document 3, when a slurry contains a powder made of a Cu — Mg — Ti alloy and is bonded in a nitrogen atmosphere using a bonding filler metal made of the slurry, there is a problem that gas remains at a bonding interface and partial discharge is likely to occur. Further, since the alloy powder is used, the melting state may become uneven depending on the composition variation of the alloy powder, and a region in which the interface reaction is insufficient may be locally formed. Further, organic matter contained in the slurry may remain at the joining interface, and the joining may become insufficient.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a copper-ceramic bonded body, an insulated circuit board, a method for producing the copper-ceramic bonded body, and a method for producing the insulated circuit board, in which a copper member made of copper or a copper alloy and a ceramic member made of aluminum oxide are reliably bonded to each other and which are excellent in migration resistance.

In order to solve the above problems and achieve the above object, a copper-ceramic joined body according to the present invention is a copper-ceramic joined body in which a copper member made of copper or a copper alloy and a ceramic member made of an aluminum oxide are joined, wherein a magnesium oxide layer is formed on the side of the ceramic member between the copper member and the ceramic member, a Mg solid solution layer in which Mg is solid-dissolved in a parent phase of Cu is formed between the magnesium oxide layer and the copper member, and one or two or more active metals selected from Ti, Zr, Nb, and Hf are present in the Mg solid solution layer.

In the copper-ceramic joined body having such a structure, a magnesium oxide layer is formed between a copper member made of copper or a copper alloy and a ceramic member made of aluminum oxide on the side of the ceramic member. The magnesium oxide layer is formed by reacting magnesium (Mg) disposed between the ceramic member and the copper member with oxygen (O) in the ceramic member, and the ceramic member is sufficiently reacted.

Further, a Mg solid solution layer in which Mg is solid-dissolved in a parent phase of Cu is formed between the magnesium oxide layer and the copper member, and one or two or more kinds of active metals selected from Cu, Ti, Zr, Nb, and Hf exist in the Mg solid solution layer, so that Mg disposed between the ceramic member and the copper member is sufficiently diffused to the copper member side, and further, the active metals disposed between the ceramic member and the copper member sufficiently react with Cu in the copper member.

Therefore, an interface reaction is sufficiently performed at the joint interface between the copper member and the ceramic member, and a copper-ceramic joint body in which the copper member and the ceramic member are reliably joined can be obtained. Further, since Ag is not present at the bonding interface, the migration resistance is also excellent.

In the copper-ceramic joined body according to the present invention, an intermetallic compound phase including Cu and the active metal may be dispersed in the Mg solid solution layer.

When Ti, Zr, or Hf is contained as the active metal, the active metal in the Mg solid solution layer exists as an intermetallic compound phase of Cu and the active metal. Therefore, the presence of the intermetallic compound phase between Cu and the active metal in the Mg solid solution layer allows Mg disposed between the ceramic member and the copper member to sufficiently diffuse toward the copper member side, and Cu to sufficiently react with the active metal, thereby making it possible to obtain a copper-ceramic joined body in which the copper member and the ceramic member are reliably joined.

In the copper-ceramic joined body of the present invention, it is preferable that Cu particles are dispersed in the magnesium oxide layer.

In this case, Cu of the copper member sufficiently reacts with the ceramic member, and a copper-ceramic joined body in which the copper member and the ceramic member are strongly joined can be obtained. The Cu particles are intermetallic compounds containing Cu simple substance or Cu, and are generated by precipitation of Cu present in a liquid phase when the magnesium oxide layer is formed.

In the copper-ceramic joined body of the present invention, it is preferable that an area ratio of a Cu — Mg intermetallic compound phase in a region between the ceramic member and the copper member, which is 50 μm from a joining surface of the ceramic member toward the copper member side, is 15% or less.

In this case, since the area ratio of the brittle Cu — Mg intermetallic compound phase is limited to 15% or less, it is possible to suppress the occurrence of cracks or the like at the bonding interface even when ultrasonic bonding or the like is performed, for example.

Examples of the Cu-Mg intermetallic compound phase include Cu₂Mg phase, CuMg₂Are equal.

In the copper-ceramic joined body of the present invention, the thickness of the magnesium oxide layer is preferably set to be in the range of 50nm to 1000 nm.

In this case, the thickness of the magnesium oxide layer formed on the ceramic member side is set to be in the range of 50nm to 1000nm, and therefore, the occurrence of cracking of the ceramic member during the load heating and cooling cycle can be suppressed.

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 a surface of a ceramic substrate made of aluminum oxide, wherein a magnesium oxide layer is formed between the copper plate and the ceramic member on the side of the ceramic member, a Mg solid solution layer in which Mg is solid-dissolved in a parent phase of Cu is formed between the magnesium oxide layer and the copper plate, and one or two or more active metals selected from Ti, Zr, Nb, and Hf are present in the Mg solid solution layer.

In the insulated circuit board having such a structure, the copper plate and the ceramic substrate are reliably bonded, and the insulated circuit board has excellent migration resistance and can be used with high reliability even under high withstand voltage conditions.

In the insulated circuit board according to the present invention, an intermetallic compound phase including Cu and the active metal may be dispersed in the Mg solid solution layer.

When Ti, Zr, Hf are contained as the active metals, the active metals in the Mg solid solution layer exist as an intermetallic compound phase of Cu and the active metals. Therefore, the presence of the Mg solid solution layer as an intermetallic compound phase of Cu and the active metal enables to obtain an insulated circuit board in which the copper plate and the ceramic substrate are reliably joined.

In the insulated circuit board according to the present invention, preferably, Cu particles are dispersed in the magnesium oxide layer.

In this case, Cu of the copper plate sufficiently reacts with the ceramic substrate, and an insulated circuit board in which the copper plate and the ceramic substrate are firmly bonded can be obtained. The Cu particles are intermetallic compounds containing Cu simple substance or Cu, and are generated by precipitation of Cu present in a liquid phase when the magnesium oxide layer is formed.

In the insulated circuit board according to the present invention, it is preferable that an area ratio of the Cu — Mg intermetallic compound phase in a region between the ceramic substrate and the copper plate, which is 50 μm from the bonding surface of the ceramic substrate toward the copper plate side, is 15% or less.

In this case, since the area ratio of the brittle Cu — Mg intermetallic compound phase is limited to 15% or less, it is possible to suppress the occurrence of cracks or the like at the bonding interface even when ultrasonic bonding or the like is performed, for example.

Examples of the Cu-Mg intermetallic compound phase include Cu₂Mg phase, CuMg₂Are equal.

In the insulated circuit board according to the present invention, the thickness of the magnesium oxide layer is preferably set to be in a range of 50nm to 1000 nm.

In this case, the thickness of the magnesium oxide layer formed on the ceramic substrate side is set to be in the range of 50nm to 1000nm, and therefore, the occurrence of cracking of the ceramic substrate during load heating and cooling cycles can be suppressed.

The method for producing a copper-ceramic bonded body according to the present invention is a method for producing a copper-ceramic bonded body, the method comprising: an active metal and Mg disposing step of disposing one or two or more active metal simple substances selected from Ti, Zr, Nb, and Hf and a Mg simple substance between the copper member and the ceramic member; a lamination step of laminating the copper member and the ceramic member via an active metal and Mg; and a bonding step of bonding the copper member and the ceramic member, which are laminated via an active metal and Mg, by applying a pressure in a lamination direction and heating the resultant in a vacuum atmosphere, wherein in the active metal and Mg disposing step, an amount of the active metal is set to 0.4 [ mu ] mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

According to the method for producing a copper-ceramic joined body having such a structure, since the simple substance of the active metal and the simple substance of Mg are disposed between the copper member and the ceramic member, and these are heated in a vacuum atmosphere in a state where they are pressurized in the stacking direction, no gas, no residue of organic matter, or the like remains at the joining interface. Further, since the simple substance of the active metal and the simple substance of Mg are arranged, the liquid phase is uniformly generated, and there is no composition variation.

In the step of preparing the active metal and Mg, the amount of the active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following range, therefore, a desired liquid phase can be sufficiently obtained in the interfacial reaction, and an excessive reaction of the ceramic member can be suppressed.

Thus, a copper-ceramic joined body in which the copper member and the ceramic member are reliably joined can be obtained. Further, since Ag is not used in the bonding, a copper-ceramic bonded body having excellent migration resistance can be obtained.

In the method for producing a copper-ceramic joined body according to the present invention, it is preferable that the pressing load in the joining step is set to be in a range of 0.049MPa to 3.4MPa, and the heating temperature in the joining step is set to be in a range of 500 ℃ to 850 ℃ when Cu and Mg are laminated in a contact state, and is set to be in a range of 670 ℃ to 850 ℃ when Cu and Mg are laminated in a non-contact state.

In this case, since the pressing load in the joining step is set in the range of 0.049MPa to 3.4MPa, the ceramic member, the copper member, the active metal and Mg can be closely attached to each other, and the interface reaction of these members can be promoted during heating.

The heating temperature in the bonding step is 500 ℃ or higher than the eutectic temperature of Cu and Mg when Cu and Mg are stacked in a contact state, and 670 ℃ or higher than the melting point of Mg when Cu and Mg are stacked in a non-contact state, and therefore a liquid phase can be sufficiently generated at the bonding interface.

Since the heating temperature in the bonding step is set to 850 ℃ or lower, the occurrence of eutectic reaction between Cu and the active metal can be suppressed, and the excessive formation of a liquid phase can be suppressed. Further, the thermal load on the ceramic member is reduced, and the deterioration of the ceramic member can be suppressed.

A method for manufacturing an insulated circuit board according to the present invention is a method for manufacturing an insulated circuit board, the method including: an active metal and Mg disposing step of disposing a simple substance of one or two or more active metals selected from Ti, Zr, Nb, and Hf and a simple substance of Mg between the copper plate and the ceramic substrate; a lamination step of laminating the copper plate and the ceramic substrate via an active metal and Mg; and a bonding step of bonding the copper plate and the ceramic substrate laminated via the active metal and Mg in a lamination direction by applying a pressure thereto and performing a heat treatment in a vacuum atmosphere, wherein in the active metal and Mg disposing step, an amount of the active metal is set to 0.4 [ mu ] mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

According to the method for manufacturing an insulated circuit board having this configuration, an insulated circuit board in which the copper plate and the ceramic substrate are reliably joined can be obtained. Further, since Ag is not used in bonding, an insulated circuit board having excellent migration resistance can be obtained.

In the method for manufacturing an insulated circuit board according to the present invention, it is preferable that the pressing load in the bonding step is set to be in a range of 0.049MPa to 3.4MPa, and the heating temperature in the bonding step is set to be in a range of 500 ℃ to 850 ℃ when Cu and Mg are laminated in a contact state, and in a range of 670 ℃ to 850 ℃ when Cu and Mg are laminated in a non-contact state.

In this case, since the pressing load in the bonding step is set in the range of 0.049MPa to 3.4MPa, the ceramic substrate, the copper plate, the active metal, and Mg can be closely attached to each other, and the interface reaction of these can be promoted during heating.

The heating temperature in the bonding step is 500 ℃ or higher than the eutectic temperature of Cu and Mg when Cu and Mg are stacked in a contact state, and 670 ℃ or higher than the melting point of Mg when Cu and Mg are stacked in a non-contact state, and therefore a liquid phase can be sufficiently generated at the bonding interface.

Since the heating temperature in the bonding step is set to 850 ℃ or lower, the occurrence of eutectic reaction between Cu and the active metal can be suppressed, and the excessive formation of a liquid phase can be suppressed. Further, the thermal load on the ceramic substrate is reduced, and the deterioration of the ceramic substrate can be suppressed.

According to the present invention, it is possible to provide a copper-ceramic joined body, an insulated circuit board, a method for producing the copper-ceramic joined body, and a method for producing the insulated circuit board, in which a copper member made of copper or a copper alloy and a ceramic member made of aluminum oxide are reliably joined and which have excellent migration resistance.

Drawings

Fig. 1 is a schematic explanatory view of a power module using an insulated circuit board according to a first embodiment of the present invention.

Fig. 2 is a schematic view of a circuit layer (copper member) and a bonding interface between a metal layer (copper member) and a ceramic substrate (ceramic member) of an insulated circuit substrate according to a first embodiment of the present invention.

Fig. 3 is a flowchart showing a method for manufacturing an insulated circuit board according to a first embodiment of the present invention.

Fig. 4 is an explanatory view showing a method for manufacturing an insulated circuit board according to a first embodiment of the present invention.

Fig. 5 is a schematic explanatory view of a power module using an insulated circuit board according to a second embodiment of the present invention.

Fig. 6 is a schematic view of a bonding interface between a circuit layer (copper member) and a ceramic substrate (ceramic member) of an insulated circuit substrate according to a second embodiment of the present invention.

Fig. 7 is a flowchart showing a method for manufacturing an insulated circuit board according to a second embodiment of the present invention.

Fig. 8 is an explanatory view showing a method for manufacturing an insulated circuit board according to a second embodiment of the present invention.

FIG. 9 is a result of observing the bonding interface between the copper plate and the ceramic substrate in the copper-ceramic bonded body of example 3 of the present invention.

FIG. 10 is an explanatory view showing a method of measuring tensile strength in example 2.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

(first embodiment)

Hereinafter, a first embodiment of the present invention will be described with reference to fig. 1 to 4.

The copper-ceramic joined body according to the present embodiment is an insulated circuit board 10 formed by joining a ceramic board 11 as a ceramic member, and a copper plate 22 (circuit layer 12) and a copper plate 23 (metal layer 13) as copper members.

Fig. 1 shows an insulated circuit board 10 according to a first embodiment of the present invention and a power module 1 using the insulated circuit board 10.

The power module 1 includes an insulating circuit board 10, a semiconductor element 3 bonded to one surface (upper side in fig. 1) of the insulating circuit board 10 via a first solder layer 2, and a heat sink 51 bonded to the other surface (lower side in fig. 1) of the insulating circuit board 10 via a second solder layer 8.

The insulated circuit board 10 includes a ceramic substrate 11, a circuit layer 12 disposed on one surface (upper surface in fig. 1) of the ceramic substrate 11, and a metal layer 13 disposed on the other surface (lower surface in fig. 1) of the ceramic substrate 11.

The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13, and in the present embodiment, is made of alumina (aluminum), which is one type of aluminum oxide. The thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5mm, and in the present embodiment, the thickness of the ceramic substrate 11 is preferably 0.635 mm.

As shown in fig. 4, the circuit layer 12 is formed by bonding a copper plate 22 made of copper or a copper alloy to one surface of the ceramic substrate 11. In the present embodiment, as the copper plate 22 constituting the circuit layer 12, a rolled plate of oxygen-free copper is used. A circuit pattern is formed on the circuit layer 12, and one surface (upper surface in fig. 1) is a mounting surface on which the semiconductor element 3 is mounted. The thickness of the circuit layer 12 is set in a range of 0.1mm to 2.0mm, and in the present embodiment, the thickness of the circuit layer 12 is preferably 0.6 mm.

As shown in fig. 4, the metal layer 13 is formed by bonding a copper plate 23 made of copper or a copper alloy to the other surface of the ceramic substrate 11. In the present embodiment, as the copper plate 23 constituting the metal layer 13, a rolled plate of oxygen-free copper is used. The thickness of the metal layer 13 is set in a range of 0.1mm to 2.0mm, and in the present embodiment, the thickness of the metal layer 13 is preferably 0.6 mm.

The heat sink 51 is used for cooling the insulating circuit board 10, and in the present embodiment, is a heat sink made of a material having good heat conductivity. In the present embodiment, the fins 51 are made of copper or a copper alloy having excellent heat conductivity. The heat sink 51 and the metal layer 13 of the insulating circuit board 10 are joined together via the second solder layer 8.

As shown in fig. 4, the ceramic substrate 11 and the circuit layer 12 (copper plate 22) and the ceramic substrate 11 and the metal layer 13 (copper plate 23) are bonded via an active metal film 24 and an Mg film 25, and the active metal film 24 is made of one or two or more active metals selected from Ti, Zr, Nb, and Hf. In the present embodiment, Ti is used as the active metal, and the active metal film 24 is a Ti film.

As shown in fig. 2, a magnesium oxide layer 31 formed on the ceramic substrate 11 side and a Mg solid solution layer 32 in which Mg is solid-dissolved in a parent phase of Cu are laminated on the bonding interface between the ceramic substrate 11 and the circuit layer 12 (copper plate 22) and the bonding interface between the ceramic substrate 11 and the metal layer 13 (copper plate 23).

The Mg solid solution layer 32 contains the above-mentioned active metal. In the present embodiment, an intermetallic compound phase 33 containing Cu and an active metal is dispersed in the Mg solid solution layer 32. In the present embodiment, Ti is used as the active metal, and Cu and Ti are exemplified as the intermetallic compound constituting the intermetallic compound phase 33, for example₄Ti、Cu₃Ti₂、Cu₄Ti₃、CuTi、CuTi₂And CuTi₃And the like.

The Mg content in the Mg solid solution layer 32 is set to be in the range of 0.01 atomic% or more and 3 atomic% or less. The thickness of the Mg solid solution layer 32 is set to be in the range of 0.1 μm to 80 μm.

In the present embodiment, Cu particles 35 are dispersed in the magnesium oxide layer 31.

The particle diameter of the Cu particles 35 dispersed in the magnesium oxide layer 31 is set to be in the range of 10nm to 100 nm. The Cu concentration in the region near the interface between the ceramic substrate 11 and the MgO layer 31 and 20% of the thickness of the MgO layer 31 is set to be in the range of 0.3 at% to 15 at%.

The thickness of the magnesium oxide layer 31 is set to be in the range of 50nm to 1000 nm. The thickness of the magnesium oxide layer 31 is more preferably set in the range of 50nm to 400 nm.

In the present embodiment, the area ratio of the Cu — Mg intermetallic compound phase in the region between the ceramic substrate 11 and the circuit layer 12 (metal layer 13) from the bonding surface of the ceramic substrate 11 to 50 μm toward the circuit layer 12 (metal layer 13) side is set to 15% or less. Examples of the Cu-Mg intermetallic compound phase include Cu₂Mg phase, CuMg₂Are equal.

In the present embodiment, regarding the Cu — Mg intermetallic compound, an elemental MAP of Mg in a region (400 μm × 600 μm) including a bonding interface was obtained under conditions of 2000 × magnification and 15kV acceleration voltage using an electron beam microanalyzer (JXA-8539F, manufactured by JEOL ltd), and a region in which a Cu concentration satisfies 5 atomic% or more and a Mg concentration satisfies 30 atomic% or more and 70 atomic% or less was set as a Cu — Mg intermetallic compound phase on an average of 5 points of quantitative analysis in a region in which the presence of Mg was confirmed.

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

As shown in fig. 4, a simple substance of one or two or more active metals selected from Ti, Zr, Nb, and Hf (in the present embodiment, a simple substance of Ti) and a simple substance of Mg (an active metal and Mg disposing step S01) are disposed 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, respectively. In the present embodiment, vapor deposition is usedAn active metal (Ti) and Mg are formed to form an active metal film 24(Ti film) and an Mg film 25, and the Mg film 25 is laminated on the copper plate 22 (copper plate 23) in a non-contact state. In the active metal and Mg preparing step S01, the amount of active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, and the amount of Mg is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

The lower limit of the amount of the active metal is preferably set to 2.8. mu. mol/cm²The upper limit of the amount of the active metal is preferably set to 18.8. mu. mol/cm²The following. The lower limit of the Mg amount is preferably set to 8.8. mu. mol/cm²The upper limit of the amount of Mg is preferably 37.0. mu. mol/cm²The following.

Next, the copper plate 22, the ceramic substrate 11, and the copper plate 23 are laminated via the active metal film 24(Ti film) and the Mg film 25 (laminating step S02).

Next, the copper plate 22, the ceramic substrate 11, and the copper plate 23 are stacked in the stacking direction, and the stacked copper plates 22, the ceramic substrate 11, and the copper plate 23 are loaded into a vacuum furnace and heated to bond the copper plates 22, the ceramic substrate 11, and the copper plates 23 (bonding step S03).

The pressing load in the bonding step S03 is set to be in the range of 0.049MPa to 3.4 MPa.

The heating temperature in the bonding step S03 is set in a range of 670 ℃ to 850 ℃ inclusive, which is equal to or higher than the melting point of Mg, because Cu and Mg are laminated in a non-contact state. The lower limit of the heating temperature is preferably 700 ℃ or higher.

The degree of vacuum in the bonding step S03 is preferably set to 1 × 10^-6Pa or more and 1 × 10^-2Pa or less.

The holding time at the heating temperature is preferably set in the range of 5min to 360 min. In order to reduce the area ratio of the Cu — Mg intermetallic compound phase, the lower limit of the holding time at the heating temperature is preferably 60min or more. The upper limit of the holding time at the heating temperature is preferably 240min or less.

As described above, the insulated circuit board 10 according to the present embodiment is manufactured through the active metal and Mg disposing step S01, the laminating step S02, and the bonding step S03.

Next, the heat sink 51 is bonded to the other surface side of the metal layer 13 of the insulating circuit board 10 (heat sink bonding step S04).

The insulating circuit board 10 and the heat sink 51 are stacked via the solder material and loaded into a heating furnace, and the insulating circuit board 10 and the heat sink 51 are solder-joined via the second solder layer 8.

Next, the semiconductor element 3 is bonded to one surface of the circuit layer 12 of the insulating circuit board 10 by soldering (semiconductor element bonding step S05).

Through the above steps, the power module 1 shown in fig. 1 is manufactured.

According to the insulated circuit board 10 (copper-ceramic joined body) of the present embodiment having the above-described configuration, the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) made of oxygen-free copper and the ceramic board 11 made of alumina, which is one type of aluminum oxide, are joined to each other through the active metal film 24(Ti film) and the Mg film 25, and the magnesium oxide layer 31 formed on the ceramic board 11 side and the Mg solid solution layer 32 in which Mg is solid-dissolved in the parent phase of Cu are stacked on the joining interface between the ceramic board 11 and the circuit layer 12 (copper plate 22) and between the ceramic board 11 and the metal layer 13 (copper plate 22).

The magnesium oxide layer 31 is formed by reaction of Mg disposed between the ceramic substrate 11 and the copper plates 22 and 23 and oxygen of the ceramic substrate 11, and the ceramic substrate 11 sufficiently reacts at the bonding interface. Further, a Mg solid solution layer 32 in which Mg is solid-dissolved in a parent phase of Cu is formed so as to be laminated on the magnesium oxide layer 31, the Mg solid solution layer 32 including the above active metal, and in the present embodiment, since an intermetallic compound phase 33 including Cu and an active metal (Ti) is dispersed in the Mg solid solution layer 31, Mg disposed between the ceramic substrate 11 and the copper plates 22, 23 is sufficiently diffused to the copper plates 22, 23 side, and further Cu sufficiently reacts with the active metal (Ti).

Thus, the interface reaction is sufficiently performed at the bonding interface between the ceramic substrate 11 and the copper plates 22 and 23, and the insulating circuit board 10 (copper-ceramic bonded body) in which the circuit layer 12 (copper plate 22) and the ceramic substrate 11, and the metal layer 13 (copper plate 23) and the ceramic substrate 11 are reliably bonded can be obtained. Further, since Ag is not present at the bonding interface, the insulated circuit board 10 (copper-ceramic bonded body) having excellent migration resistance can be obtained.

In particular, in the present embodiment, since the Cu particles 35 are dispersed in the magnesium oxide layer 31, Cu of the copper plates 22 and 23 sufficiently reacts with the bonding surface of the ceramic substrate 11, and the insulating circuit board 10 (copper-ceramic bonded body) in which the copper plates 22 and 23 and the ceramic substrate 11 are firmly bonded can be obtained.

Further, the method for manufacturing the insulated circuit board 10 (copper-ceramic bonded body) according to the present embodiment includes: an active metal and Mg disposing step S01 of disposing a simple substance of an active metal (Ti) (active metal film 24) and a simple substance of Mg (Mg film 25) between the copper plates 22, 23 and the ceramic substrate 11; a laminating step S02 of laminating the copper plates 22 and 23 and the ceramic substrate 11 via the active metal film 24 and the Mg film 25; and a bonding step S03 of bonding the copper plate 22, the ceramic substrate 11, and the copper plate 23 stacked in the stacking direction by applying a pressure thereto and performing a heat treatment in a vacuum atmosphere, so that no gas, organic matter, or the like remains at the bonding interface. Further, since the simple substance of the active metal (Ti) and the simple substance of Mg are arranged, a liquid phase is uniformly generated, and there is no compositional variation.

In addition, in the active metal and Mg disposing step S01, the amount of active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²In the following range, a desired liquid phase can be sufficiently obtained in the interfacial reaction, and an excessive reaction of the ceramic substrate 11 can be suppressed.

This makes it possible to obtain the insulated circuit board 10 (copper-ceramic bonded body) in which the copper plates 22 and 23 and the ceramic board 11 are reliably bonded. Further, since Ag is not used in bonding, the insulated circuit board 10 having excellent migration resistance can be obtained.

The active metal content is less than 0.4 mu mol/cm²And the amount of Mg is less than 7.0 mu mol/cm²In this case, the interface reaction may become insufficient, and the bonding rate may be lowered. And the active metal content is more than 47.0 mu mol/cm²In this case, the intermetallic compound phase 33 which is relatively hard and contains a large amount of active metal is excessively generated, and the Mg solid solution layer 32 may become excessively hard, thereby causing the metal to be excessively hardCracks occur in the ceramic substrate 11. And the Mg amount is more than 143.2 mu mol/cm²In this case, the decomposition reaction of the ceramic substrate 11 excessively proceeds, so that Al is excessively generated, and an intermetallic compound with Cu, an active metal (Ti), or Mg is generated in a large amount, thereby causing cracking of the ceramic substrate 11.

As is clear from the above, in the present embodiment, the amount of the active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, and the amount of Mg is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

In the present embodiment, since the pressing load in the bonding step S03 is set to 0.049MPa or more, the ceramic substrate 11, the copper plates 22 and 23, and the active metal film 24(Ti film) and the Mg film 25 can be closely attached to each other, and the interface reaction of these can be promoted during heating. Since the pressing load in the bonding step S03 is set to 3.4MPa or less, cracking and the like of the ceramic substrate 11 can be suppressed.

In the present embodiment, Cu and Mg are laminated in a non-contact state, and the heating temperature in the bonding step S03 is set to 670 ℃. On the other hand, since the heating temperature in the bonding step S03 is set to 850 ℃ or lower, the occurrence of eutectic reaction between Cu and the active metal (Ti) can be suppressed, and the excessive formation of a liquid phase can be suppressed. Further, the thermal load on the ceramic substrate 11 is reduced, and deterioration of the ceramic substrate 11 can be suppressed.

(second embodiment)

Next, a second embodiment of the present invention will be described with reference to fig. 5 to 8.

The copper-ceramic bonded body according to the present embodiment is an insulated circuit board 110 configured by bonding a ceramic substrate 111 as a ceramic member and a copper plate 122 (circuit layer 112) as a copper member.

Fig. 5 shows an insulated circuit board 110 according to a second embodiment of the present invention and a power module 101 using the insulated circuit board 110.

The power module 101 includes an insulating circuit board 110, a semiconductor element 3 bonded to one (upper side in fig. 5) surface of the insulating circuit board 110 via a solder layer 2, and a heat sink 151 disposed on the other (lower side in fig. 5) surface of the insulating circuit board 110.

The solder layer 2 is made of, for example, a Sn-Ag type, Sn-In type, or Sn-Ag-Cu type solder material.

The insulated circuit board 110 includes a ceramic substrate 111, a circuit layer 112 disposed on one surface (upper surface in fig. 5) of the ceramic substrate 111, and a metal layer 113 disposed on the other surface (lower surface in fig. 5) of the ceramic substrate 111.

The ceramic substrate 111 prevents electrical connection between the circuit layer 112 and the metal layer 113, and in the present embodiment, is made of alumina, which is one type of aluminum oxide. The thickness of the ceramic substrate 111 is set to be in the range of 0.2 to 1.5mm, and in the present embodiment, 0.635 mm.

As shown in fig. 8, the circuit layer 112 is formed by bonding a copper plate 122 made of copper or a copper alloy to one surface of the ceramic substrate 111. In the present embodiment, as the copper plate 122 constituting the circuit layer 112, a rolled plate of oxygen-free copper is used. A circuit pattern is formed on the circuit layer 112, and one surface (upper surface in fig. 5) is a mounting surface on which the semiconductor element 3 is mounted. The thickness of the circuit layer 112 is set to be in the range of 0.1mm to 2.0mm, and in the present embodiment, 0.6 mm.

As shown in fig. 8, the metal layer 113 is formed by bonding an aluminum plate 123 to the other surface of the ceramic substrate 111. In the present embodiment, the metal layer 113 is formed by joining an aluminum plate 123, which is a rolled plate of aluminum having a purity of 99.99 mass% or more (so-called 4N aluminum), to the ceramic substrate 111. The 0.2% yield strength of the aluminum plate 123 was set to 30N/mm²The following. The thickness of the metal layer 113 (aluminum plate 123) is set to be in the range of 0.5mm to 6mm, and in the present embodiment, 2.0 mm. As shown in fig. 8, the metal layer 113 is formed by bonding an aluminum plate 123 to the ceramic substrate 111 with an Al — Si based brazing material 128.

The heat sink 151 is used for cooling the insulating circuit board 110, and in the present embodiment, is a heat sink made of a material having good heat conductivity. In the present embodiment, the fins 151 are made of a6063 (aluminum alloy). In the present embodiment, the heat sink 151 is bonded to the metal layer 113 of the insulating circuit board 110 using, for example, an Al — Si based solder.

As shown in fig. 8, the ceramic substrate 111 and the circuit layer 112 (copper plate 122) are bonded via an active metal film 124 and an Mg film 125, and the active metal film 124 is made of one or two or more active metals selected from Ti, Zr, Nb, and Hf. In the present embodiment, Zr and Hf are used as the active metals, and the active metal film 124 is formed by co-evaporation of Zr and Hf.

As shown in fig. 6, a magnesium oxide layer 131 formed on the ceramic substrate 111 side and a Mg solid solution layer 132 in which Mg is solid-dissolved in a parent phase of Cu are laminated on the bonding interface between the ceramic substrate 111 and the circuit layer 112 (copper plate 122).

The Mg solid solution layer 132 contains the above-described active metal. In the present embodiment, an intermetallic compound phase 133 containing Cu and active metals (Zr and Hf) is dispersed in the Mg solid solution layer 132. In the present embodiment, Zr and Hf are used as the active metals, and as the intermetallic compound constituting the intermetallic compound phase 133 containing Cu, Zr, and Hf, for example, Cu is mentioned₅Zr、Cu₅₁Zr₁₄、Cu₈Zr₃、Cu₁₀Zr₇、CuZr、Cu₅Zr₈、CuZr₂、Cu₅₁Hf₁₄、Cu₈Hf₃、Cu₁₀Hf₇、CuHf₂And the like. The Mg content in the Mg solid solution layer 132 is set to be in the range of 0.01 atomic% or more and 3 atomic% or less. The thickness of the Mg solid solution layer 132 is set to be in the range of 0.1 μm to 80 μm.

In the present embodiment, Cu particles 135 are dispersed in the magnesium oxide layer 131.

The particle diameter of the Cu particles 135 dispersed in the magnesium oxide layer 131 is set to be in the range of 10nm to 100 nm. The Cu concentration in the region near the interface between the ceramic substrate 111 and the magnesium oxide layer 131 and 20% of the thickness of the magnesium oxide layer 131 is set to be in the range of 0.3 at% to 15 at%.

The thickness of the magnesium oxide layer 131 is set to be in the range of 50nm to 1000 nm. The thickness of the magnesium oxide layer 131 is more preferably set in the range of 50nm to 400 nm.

In the present embodiment, the area ratio of the Cu — Mg intermetallic compound phase in a region between the ceramic substrate 111 and the circuit layer 112, which is 50 μm from the bonding surface of the ceramic substrate 111 toward the circuit layer 112 side, is set to 15% or less.

Examples of the Cu-Mg intermetallic compound phase include Cu₂Mg phase, CuMg₂Are equal.

In the present embodiment, regarding the Cu — Mg intermetallic compound, an elemental MAP of Mg in a region (400 μm × 600 μm) including a bonding interface was obtained under conditions of 2000 × magnification and 15kV acceleration voltage using an electron beam microanalyzer (JXA-8539F, manufactured by JEOL ltd), and a region in which a Cu concentration satisfies 5 atomic% or more and a Mg concentration satisfies 30 atomic% or more and 70 atomic% or less was set as a Cu — Mg intermetallic compound phase on an average of 5 points of quantitative analysis in a region in which the presence of Mg was confirmed.

Next, a method for manufacturing the insulated circuit board 110 according to the present embodiment will be described with reference to fig. 7 and 8.

As shown in fig. 8, one or two or more kinds of simple substances of active metals (in the present embodiment, a simple substance of Zr and a simple substance of Hf) and a simple substance of Mg (an active metal and Mg disposing step S101) selected from Ti, Zr, Nb, and Hf are disposed between the copper plate 122 serving as the circuit layer 112 and the ceramic substrate 111. In this embodiment, the active metal (Zr and Hf) and Mg are deposited to form the active metal film 124 and the Mg film 125, and the Mg film 125 is formed to be in contact with the copper plate 122.

In the active metal and Mg preparing step S101, the amount of active metal is set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, and the amount of Mg is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²Within the following ranges.

The active metal content is less than 0.4 mu mol/cm²And the amount of Mg is less than 7.0 mu mol/cm²In this case, the interface reaction may become insufficient, and the bonding rate may become insufficientAnd decreases. And the active metal content is more than 47.0 mu mol/cm²In this case, an intermetallic compound phase 133 which is relatively hard and contains a large amount of active metal is excessively generated, and the Mg solid solution layer 132 becomes excessively hard, and thus the ceramic substrate 111 may be broken. And the Mg amount is more than 143.2 mu mol/cm²In this case, the decomposition reaction of the ceramic substrate 111 excessively proceeds, so that Al is excessively generated, and an intermetallic compound with Cu, an active metal (Ti), or Mg is generated in a large amount, thereby causing cracking of the ceramic substrate 111.

The lower limit of the amount of the active metal is preferably set to 2.8. mu. mol/cm²The upper limit of the amount of the active metal is preferably set to 18.8. mu. mol/cm²The following. The lower limit of the Mg amount is preferably set to 8.8. mu. mol/cm²The upper limit of the amount of Mg is preferably 37.0. mu. mol/cm²The following.

Next, the copper plate 122 and the ceramic substrate 111 are laminated via the active metal film 124 and the Mg film 125 (laminating step S102).

As shown in fig. 8, in the present embodiment, aluminum plate 123 to be metal layer 113 is laminated on the other surface side of ceramic substrate 111 via Al — Si based brazing material 128.

Next, the copper plate 122, the ceramic substrate 111, and the aluminum plate 123 stacked in the stacking direction are pressed, and then, the copper plate 122, the ceramic substrate 111, and the aluminum plate 123 are placed in a vacuum furnace and heated to bond them (bonding step S103).

The pressing load in the bonding step S103 is set to be in the range of 0.049MPa to 3.4 MPa.

In addition, since Cu and Mg are laminated in a contact state at the heating temperature in the bonding step S103, the eutectic temperature of Mg and Cu is 500 ℃ or higher, and the eutectic temperature of Cu and the active metal (Zr and Hf) is lower. The lower limit of the heating temperature is preferably 700 ℃ or higher.

In the present embodiment, since the aluminum plate 123 is joined using the Al — Si based brazing material 128, the heating temperature is set in the range of 600 ℃ to 650 ℃.

The degree of vacuum in the bonding step S103 is preferably set to 1 × 10^-6Pa or more and 1 × 10^-2Pa or less.

The holding time at the heating temperature is preferably set within a range of 5min to 360 min. In order to reduce the area ratio of the Cu — Mg intermetallic compound phase, the lower limit of the holding time at the heating temperature is preferably 60min or more. The upper limit of the holding time at the heating temperature is preferably 240min or less.

As described above, the insulating circuit board 110 according to the present embodiment is manufactured through the active metal and Mg disposing step S101, the laminating step S102, and the bonding step S103.

Next, the heat sink 151 is bonded to the other surface side of the metal layer 113 of the insulating circuit board 110 (heat sink bonding step S104).

The insulated circuit board 110 and the heat sink 151 are laminated via a brazing material, and are loaded into a vacuum furnace while being pressurized in the lamination direction, and are soldered. Thereby, the metal layer 113 of the insulating circuit board 110 and the heat sink 151 are bonded. In this case, for example, an Al-Si-based brazing filler metal foil having a thickness of 20 to 110 μm can be used as the brazing filler metal, and the brazing temperature is preferably set to a temperature lower than the heating temperature in the joining step S103.

Next, the semiconductor element 3 is bonded to one surface of the circuit layer 112 of the insulating circuit board 110 by soldering (semiconductor element bonding step S105).

Through the above steps, the power module 101 shown in fig. 5 is manufactured.

According to the insulated circuit board 110 (copper-ceramic bonded body) of the present embodiment having the above-described configuration, the copper plate 122 (circuit layer 112) and the ceramic substrate made of aluminum oxide are bonded via the active metal film 124 and the Mg film 125, the magnesium oxide layer 131 formed on the ceramic substrate 111 side and the Mg solid solution layer 132 in which Mg is solid-dissolved in the parent phase of Cu are laminated at the bonding interface between the ceramic substrate 111 and the circuit layer 112 (copper plate 122), and the active metal is present in the Mg solid solution layer 132, and the intermetallic compound phase 133 including Cu and the active metal is dispersed in the Mg solid solution layer 132 in the present embodiment, so that the insulated circuit board 110 (copper-ceramic bonded body) in which the circuit layer 112 (copper plate 122) and the ceramic substrate 111 are reliably bonded can be obtained as in the first embodiment. Further, since Ag is not present at the bonding interface, the insulating circuit board 110 (copper-ceramic bonded body) having excellent migration resistance can be obtained.

In the present embodiment, since the Cu particles 135 are dispersed in the magnesium oxide layer 131, Cu of the copper plate 122 sufficiently reacts with the bonding surface of the ceramic substrate 111, and the insulating circuit substrate 110 (copper-ceramic bonded body) in which the circuit layer 112 (copper plate 122) and the ceramic substrate 111 are firmly bonded can be obtained.

Further, according to the method for producing the insulated circuit board 110 (copper-ceramic bonded body) of the present embodiment, similarly to the first embodiment, it is possible to obtain the insulated circuit board 110 (copper-ceramic bonded body) in which the copper plate 122 and the ceramic substrate 111 are reliably bonded by appropriately generating a liquid phase at the bonding interface between the circuit layer 112 (copper plate 122) and the ceramic substrate 111 and sufficiently performing an interface reaction. Further, since Ag is not used in bonding, the insulated circuit board 110 having excellent migration resistance can be obtained.

In the present embodiment, Cu and Mg are laminated in a contact state, and the heating temperature in the bonding step S103 is set to 500 ℃ or higher, which is the eutectic temperature of Cu and Mg, and therefore, a liquid phase can be sufficiently generated at the bonding interface.

In addition, in the present embodiment, in the laminating step S102, the aluminum plate 123 is laminated on the other surface side of the ceramic substrate 111 via the Al — Si-based brazing material 128, and the copper plate 122 and the ceramic substrate 111, and the ceramic substrate 111 and the aluminum plate 123 are simultaneously joined, so that the insulated circuit board 110 including the circuit layer 112 made of copper and the metal layer 113 made of aluminum can be efficiently manufactured. Furthermore, the occurrence of warpage in the insulated circuit board 110 can be suppressed.

The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and can be modified as appropriate within a range not departing from the technical spirit of the present invention.

For example, although a copper plate constituting the circuit layer or the metal layer is described as a rolled plate of oxygen-free copper, the invention is not limited thereto, and may be formed of other copper or copper alloy.

In the second embodiment, the aluminum sheet constituting the metal layer is described as a rolled sheet of pure aluminum having a purity of 99.99 mass%, but the invention is not limited thereto, and may be formed of other aluminum or aluminum alloy such as aluminum having a purity of 99 mass% (2N aluminum).

In the present embodiment, the ceramic substrate is made of alumina, which is one type of aluminum oxide, but the ceramic substrate is not limited to this, and may be reinforced aluminum oxide containing zirconia or the like.

The heat sink is exemplified as the heat sink, but the heat sink is not limited thereto, and the structure of the heat sink is not particularly limited. For example, the cooling member may be a member having a flow path through which a refrigerant flows or a member having a cooling fin. Further, as the heat sink, a composite material (for example, AlSiC or the like) containing aluminum or an aluminum alloy can also be used.

Further, a buffer layer made of aluminum or an aluminum alloy, or a composite material containing aluminum (for example, AlSiC) may be provided between the top plate portion of the heat sink or the heat sink and the metal layer.

In the present embodiment, the description has been given of the case where the active metal film and the Mg film are formed in the active metal and Mg disposing step, but the present invention is not limited to this, and the active metal and Mg may be co-deposited. In this case, the active metal film and the Mg film formed do not undergo alloying, and the simple substance of the active metal and the simple substance of Mg are disposed. Since Mg and Cu are in contact with each other when the active metal and the Mg film are formed by co-evaporation, the lower limit of the heating temperature in the bonding step can be set to 500 ℃.

In the present embodiment, the description has been given of the case where Ti, Zr, and Hf are used as the active metal, but the present invention is not limited thereto, and one or two or more selected from Ti, Zr, Nb, and Hf may be used as the active metal.

When Zr is used as the active metal, Zr exists as an intermetallic compound phase with Cu in the Mg solid solution layer. As the intermetallic compound constituting the intermetallic compound phase, for example, Cu can be mentioned₅Zr、Cu₅₁Zr₁₄、Cu₈Zr₃、Cu₁₀Zr₇、CuZr、Cu₅Zr₈And CuZr₂And the like.

When Hf is used as the active metal, Hf exists as an intermetallic compound phase with Cu in the Mg solid solution layer. As the intermetallic compound constituting the intermetallic compound phase, for example, Cu can be mentioned₅₁Hf₁₄、Cu₈Hf₃、Cu₁₀Hf₇And CuHf₂And the like.

When Ti and Zr are used as the active metal, the Ti and Zr exist as an intermetallic compound phase including Cu and the active metal in the Mg solid solution layer. As the intermetallic compound constituting the intermetallic compound phase, Cu can be mentioned_1.5Zr_0.75Ti_0.75And the like.

When Nb is used as the active metal, Nb exists as a solid solution in the Mg solid solution layer.

In addition, in the active metal and Mg disposing step, the amount of active metal at the bonding interface was set to 0.4. mu. mol/cm²Above and 47.0. mu. mol/cm²In the following range, the Mg amount is set to 7.0. mu. mol/cm²Above 143.2. mu. mol/cm²In the following range, for example, the active metal film and the Mg film may be laminated in a multilayer manner of Mg film/active metal film/Mg film. Alternatively, a Cu film may be formed between the active metal film and the Mg film.

The simple substance of the active metal and the simple substance of Mg can be prepared into a foil material, and can also be formed into a film by sputtering.

Further, a clad material in which a simple substance of an active metal or a simple substance of Mg is laminated may be used, or a paste containing a simple substance of an active metal or a simple substance of Mg may be printed.

In the present embodiment, the power semiconductor element is mounted on the circuit layer of the insulating circuit board to constitute the power module, but the present invention is not limited to this. For example, an LED module may be configured by mounting an LED element on an insulating circuit board, or a thermoelectric module may be configured by mounting a thermoelectric element on a circuit layer of an insulating circuit board.