JP6780561B2 - Manufacturing method of joint, manufacturing method of insulated circuit board, and joint, insulated circuit board - Google Patents

Description

The present invention is a method for manufacturing a joined body including a ceramic member, an aluminum member made of aluminum or an aluminum alloy bonded to the ceramic member, and a copper member made of copper or a copper alloy bonded to the aluminum member. , A method for manufacturing an insulated circuit board, and a joint and 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 board having a circuit layer made of a conductive material 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. Therefore, as a substrate on which the power semiconductor element is mounted, for example, AlN (aluminum nitride) is used. An insulated circuit board comprising a ceramic substrate made of aluminum), Al ₂ O ₃ (alumina), etc., and a circuit layer formed by joining a metal plate having excellent conductivity to one surface of the ceramic substrate. It has been widely used in the past.

Further, in the above-mentioned insulated circuit board, a metal plate having excellent conductivity is joined to one surface of the ceramics substrate to form a circuit layer, and a metal plate having excellent heat dissipation is joined to the other surface to form a metal. Layered structures are also provided.
Here, as the circuit layer and the metal layer of the insulating circuit board, those using a bonded body in which an aluminum layer and a copper layer are laminated are proposed.

For example, Patent Document 1-4 proposes an insulated circuit board having a structure in which a circuit layer and a metal layer are laminated with an aluminum layer and a copper layer. In these insulated circuit boards, by arranging an aluminum layer having a relatively low deformation resistance on the ceramic substrate side, thermal stress caused by the difference in thermal expansion coefficient between the ceramic substrate and the circuit layer and the metal layer is absorbed. , Cracking of the ceramic substrate can be suppressed. Further, in the copper layer having excellent thermal conductivity, the heat generated by the semiconductor element or the like can be spread in the plane direction, and the heat dissipation characteristics are improved.

Here, when the aluminum layer and the copper layer are directly bonded, the aluminum and copper react with each other to generate a large amount of relatively brittle and hard intermetallic compound between aluminum and copper, and when a cold cycle load is applied, There was a risk that cracks would occur at the joint interface between the aluminum layer and the copper layer. Therefore, in Patent Documents 1-4, a barrier layer made of titanium, chromium, nickel, or the like is formed between the aluminum layer and the copper layer.

Japanese Unexamined Patent Publication No. 11-097807 Japanese Unexamined Patent Publication No. 11-195854 Japanese Unexamined Patent Publication No. 2001-053404 JP-A-2014-0723664

By the way, recently, power semiconductor elements, LED elements, thermoelectric elements, etc. mounted on an insulated circuit board tend to have a high heat generation density, and the insulated circuit board has more excellent heat dissipation characteristics than before. It has been demanded.
Here, as described above, in the case where the barrier layer is formed between the aluminum layer and the copper layer, the thermal conductivity of the barrier layer is lower than that of the aluminum layer and the copper layer, so that the barrier layer has thermal resistance. Therefore, there is a problem that the heat dissipation characteristics are deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and can suppress the formation of a liquid phase at the bonding interface between the aluminum member and the copper member, can reliably bond the ceramic member and the aluminum member, and can be joined to the aluminum member. A method for manufacturing a bonded body, a method for manufacturing an insulating circuit board, and a bonded body and insulation, which can manufacture a bonded body having excellent heat dissipation characteristics without a barrier layer having a large thermal resistance between the copper member and the copper member. It is an object of the present invention to provide a circuit board.

In order to solve the above-mentioned problems, the method for producing a bonded body of the present invention comprises a ceramic member, an aluminum member made of aluminum or an aluminum alloy bonded to the ceramic member, and copper or copper bonded to the aluminum member. A method for manufacturing a bonded body including a copper member made of an alloy, wherein the ceramic member and the aluminum member are laminated via a bonding material, and the aluminum member and the copper member are laminated via a nickel layer. A laminating step of laminating the laminated ceramic member, the aluminum member, and the copper member are heated in a state of being pressurized in the laminating direction and held in a temperature range of 620 ° C. or higher and 642 ° C. or lower. After this high temperature holding step, a low temperature holding step of holding at 500 ° C. or higher and lower than the eutectic temperature of aluminum and copper is provided. In the high temperature holding step, the ceramic member and the aluminum member are held. It is characterized in that the aluminum member and the nickel layer and the nickel layer and the copper member are bonded by solid phase diffusion, respectively, and in the low temperature holding step, the Ni atom of the nickel layer is diffused to eliminate the nickel layer. There is.

According to the method for manufacturing a bonded body having this configuration, the ceramic member and the aluminum member are laminated via a bonding material, and the aluminum member and the copper member are laminated via a nickel layer, and these are laminated. Since it has a high temperature holding step of pressurizing and heating in the direction and holding it in a temperature range of 620 ° C. or higher and 642 ° C. or lower, the ceramic member and the aluminum member can be reliably joined, and the aluminum member and the nickel layer can be joined. , And the nickel layer and the copper member can be reliably bonded by solid-phase diffusion bonding, respectively. Further, the nickel layer can prevent the formation of a liquid phase without direct contact between the aluminum member and the copper member.

Then, after the high temperature holding step, the low temperature holding step of holding the nickel layer at 500 ° C. or higher and lower than the eutectic temperature of aluminum and copper is provided, so that the Ni atom of the nickel layer is diffused and the nickel layer disappears. Can be made to. Therefore, it is possible to manufacture a bonded body having excellent heat dissipation characteristics without the presence of a nickel layer serving as a thermal resistance. Since the upper limit of the temperature in the low temperature holding step is lower than the eutectic temperature of Al and Cu, the nickel layer disappears in the low temperature holding step, and the intermetallic compound containing Al and the intermetallic compound containing Cu are directly produced. It is possible to suppress the formation of a liquid phase even when they come into contact with each other.

Here, in the method for manufacturing a bonded body of the present invention, the thickness of the nickel layer disposed between the aluminum member and the copper member in the laminating step is 0.01 mm or more and 0.05 mm or less. It is preferably within the range.
In this case, in the laminating step, the thickness of the nickel layer disposed between the aluminum member and the copper member (that is, the thickness of the nickel layer in the state before joining) is set to 0.01 mm or more. Therefore, the nickel layer can be left after the high temperature holding step, and the formation of a large amount of intermetallic compound between aluminum and copper can be suppressed. On the other hand, in the laminating step, the thickness of the nickel layer (thickness of the nickel layer in the state before joining) arranged between the aluminum member and the copper member is set to 0.05 mm or less. In the low temperature holding step, the nickel layer can be eliminated in a relatively short time.

The method for manufacturing an insulated circuit board of the present invention is an insulating circuit in which a circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of a ceramics substrate. It is a method for manufacturing a substrate, and is characterized in that the circuit layer is formed by the above-mentioned method for manufacturing a bonded body.

In the method for manufacturing an insulated circuit board of the present invention, a circuit layer is arranged on one surface of a ceramics substrate, and an aluminum layer made of aluminum or an aluminum alloy and copper made of copper or a copper alloy are formed on the other surface of the ceramics substrate. It is a method for manufacturing an insulated circuit board on which a metal layer formed by laminating layers is formed, and is characterized in that the metal layer is formed by the above-mentioned method for manufacturing a bonded body.

In the method for manufacturing an insulated circuit board of the present invention, a circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of a ceramics substrate. A method for manufacturing an insulated circuit board in which a metal layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on the other surface of the substrate. The metal layer is formed by the above-mentioned method for producing a bonded body.

In the method for manufacturing an insulated circuit board of the present invention having the above configuration, at least one or both of a circuit layer formed on one surface of a ceramic substrate and a metal layer formed on the other surface of the ceramic substrate. Is formed by the above-mentioned method for manufacturing a bonded body, so that an insulated circuit board having excellent heat dissipation characteristics is manufactured because there is no nickel layer which becomes a thermal resistance between the aluminum layer and the copper layer. be able to. Further, in the high temperature holding step, since the nickel layer remains between the aluminum layer and the copper layer, it is possible to suppress the formation of a liquid phase without the aluminum layer and the copper layer coming into direct contact with each other.

The joined body of the present invention is a joined body including a ceramic member, an aluminum member made of aluminum or an aluminum alloy bonded to the ceramic member, and a copper member made of copper or a copper alloy bonded to the aluminum member. At the bonding interface between the aluminum member and the copper member, an Al—Ni metal compound layer containing an Al and Ni metal compound is formed on the aluminum member side, and the copper member side has an Al—Ni metal compound layer. A Cu—Ni solid solution layer in which Ni is solid-dissolved is formed in the matrix phase of Cu, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated.

In the bonded body having this configuration, at the bonding interface between the aluminum member and the copper member, the Al—Ni intermetallic compound layer formed on the aluminum member side and the Cu—Ni solid solution layer formed on the copper member side. , Are directly laminated, so that the nickel layer that acts as a thermal resistance does not remain, and the heat dissipation characteristics are excellent.

The insulated circuit board of the present invention is an insulated circuit board in which a circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of a ceramics substrate. At the bonding interface between the aluminum layer and the copper layer, an Al—Ni metal compound layer containing an Al and Ni metal compound is formed on the aluminum layer side, and Cu is formed on the copper layer side. A Cu—Ni solid solution layer in which Ni is solid-dissolved is formed in the matrix phase, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated.

In the insulated circuit substrate of the present invention, a circuit layer is arranged on one surface of the ceramic substrate, and an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy are formed on the other surface of the ceramic substrate. An insulating circuit board on which a laminated metal layer is formed, and at the bonding interface between the aluminum layer and the copper layer, an Al—Ni metal containing an intermetallic compound of Al and Ni on the aluminum layer side. An inter-compound layer is formed, and a Cu-Ni solid solution layer in which Ni is solid-dissolved in the Cu matrix is formed on the copper layer side, and the Al-Ni metal-metal compound layer and the Cu-Ni solid solution layer are formed. It is characterized in that and are directly laminated.

In the insulated circuit substrate of the present invention, a circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of the ceramics substrate, and the other of the ceramics substrates. An insulating circuit board in which a metal layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on the surface of the insulating circuit substrate, and the joining of the aluminum layer and the copper layer. At the interface, an Al—Ni intermetallic compound layer containing an Al and Ni intermetallic compound is formed on the aluminum layer side, and Cu—Ni in which Ni is solid-dissolved in the Cu matrix on the copper layer side. A solid solution layer is formed, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated.

In the insulated circuit board having these configurations, at least one or both of the circuit layer formed on one surface of the ceramic substrate and the metal layer formed on the other surface of the ceramic substrate are aluminum layers made of aluminum or an aluminum alloy. The structure is such that a copper layer made of copper or a copper alloy is laminated, and at the bonding interface between the aluminum layer and the copper layer, an Al—Ni intermetallic compound layer formed on the aluminum layer side and the copper Since the Cu—Ni solid solution layer formed on the layer side is directly laminated, the nickel layer which becomes the thermal resistance does not remain, and the heat dissipation characteristics are excellent.

According to the present invention, the formation of a liquid phase is suppressed at the bonding interface between the aluminum member and the copper member, the ceramic member and the aluminum member can be reliably bonded, and a large thermal resistance is obtained between the aluminum member and the copper member. It is possible to provide a method for manufacturing a bonded body, a method for manufacturing an insulated circuit board, and a bonded body and an insulated circuit board, which do not have a barrier layer and can manufacture a bonded body having excellent heat dissipation characteristics.

It is sectional drawing which shows the power module using the junction and the insulating circuit board which are embodiment of this invention. FIG. 5 is an enlarged cross-sectional view of a main part showing the vicinity of the bonding interface of the bonded body (circuit layer and metal layer) shown in FIG. It is a flow chart which shows the manufacturing method of the insulation circuit board shown in FIG. It is explanatory drawing which shows the manufacturing method of the insulation circuit board shown in FIG. It is a graph which shows the temperature history in a high temperature holding process and a low temperature holding process. It is an enlarged explanatory view of the bonding interface of an aluminum layer and a copper layer in a high temperature holding process. It is an enlarged explanatory view of the bonding interface of an aluminum layer and a copper layer in a low temperature holding process. It is sectional drawing which shows the power module using the junction and the insulating circuit board which are other embodiments of this invention. It is sectional drawing which shows the power module using the junction and the insulating circuit board which are other embodiments of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that each of the following embodiments is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified. Further, in the drawings used in the following description, in order to make the features of the present invention easy to understand, the main parts may be enlarged for convenience, and the dimensional ratios of the respective components are the same as the actual ones. Is not always the case.

FIG. 1 shows a power module 1 using an insulated circuit board 10 according to an embodiment of the present invention. In the bonded body of the present embodiment, in the insulating circuit board 10 shown in FIG. 1, the ceramic substrate 11 as a ceramic member, the aluminum layers 21 and 31 as aluminum members, and the copper layers 22 and 32 as copper members are joined. It is said that the circuit layer 20 and the metal layer 30 are formed.

The power module 1 shown in FIG. 1 includes an insulating circuit board 10, a power semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the insulating circuit board 10 via a first solder layer 2, and an insulating circuit. A heat sink 41 bonded to the lower side of the substrate 10 via a second solder layer 42 is provided.

The power semiconductor element 3 is made of a semiconductor material such as Si. The first solder layer 2 for joining the insulating circuit board 10 and the power semiconductor element 3 is, for example, a Sn-Ag-based, Sn-Cu-based, Sn-In-based, or Sn-Ag-Cu-based solder material (so-called lead-free). Solder material).

The heat sink 41 is for dissipating heat on the insulating circuit board 10 side. The heat sink 41 is made of copper or a copper alloy, and in this embodiment, it is made of oxygen-free copper. The second solder layer 42 that joins the insulating circuit board 10 and the heat sink 41 is, for example, a Sn-Ag-based, Sn-Cu-based, Sn-In-based, or Sn-Ag-Cu-based solder material (so-called lead-free solder material). ).

As shown in FIG. 1, the insulating circuit board 10 according to the present embodiment includes a ceramic substrate 11, a circuit layer 20 disposed on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and ceramics. It includes a metal layer 30 disposed on the other surface (lower surface in FIG. 1) of the substrate 11.

Ceramic substrate 11 is, for example, aluminum nitride (AlN), silicon nitride _{(Si 3 N} 4), is composed of a high insulation property such as alumina _(Al 2 _{O 3)} ceramic. In this embodiment, it is made of aluminum nitride (AlN). The thickness of the ceramic substrate 11 is set within the range of 0.2 to 1.5 mm, and in this embodiment, it is set to 0.635 mm.

As shown in FIG. 1, the circuit layer 20 has an aluminum layer 21 arranged on one surface of the ceramic substrate 11 and a copper layer 22 laminated on one surface of the aluminum layer 21. There is.
Here, the thickness of the aluminum layer 21 in the circuit layer 20 is set within the range of 0.1 mm or more and 3.0 mm or less, and is set to 0.4 mm in the present embodiment.
The thickness of the copper layer 22 in the circuit layer 20 is set within the range of 0.1 mm or more and 6.0 mm or less, and is set to 1.0 mm in the present embodiment.

As shown in FIG. 1, the metal layer 30 has an aluminum layer 31 arranged on the other surface of the ceramic substrate 11 and a copper layer 32 laminated on the other surface of the aluminum layer 31. There is.
Here, the thickness of the aluminum layer 31 in the metal layer 30 is set within the range of 0.1 mm or more and 3.0 mm or less, and is set to 0.4 mm in the present embodiment.
The thickness of the copper layer 32 in the metal layer 30 is set within the range of 0.1 mm or more and 6.0 mm or less, and in this embodiment, it is set to 1.0 mm.

As shown in FIG. 4, the aluminum layers 21 and 31 are formed by joining the aluminum plates 51 and 61 to one surface and the other surface of the ceramic substrate 11.
The aluminum plates 51 and 61 to be the aluminum layers 21 and 31 are made of aluminum having a purity of 99 mass% or more and aluminum having a purity of 99.99 mass% or more.

As shown in FIG. 4, the copper layers 22 and 32 are formed by joining copper plates 52 and 62 made of copper or a copper alloy to one surface and the other surface of the aluminum layers 21 and 31. In the present embodiment, the copper plates 52 and 62 constituting the copper layers 22 and 32 are rolled plates of oxygen-free copper.

Here, an enlarged view of the bonding interface between the aluminum layers 21 and 31 and the copper layers 22 and 32 is shown in FIG.
At the bonding interface between the aluminum layers 21 and 31 and the copper layers 22 and 32, Al—Ni intermetallic compound layers 25 and 35 containing an Al and Ni intermetallic compound are formed on the aluminum layers 21 and 31 side, and copper is formed. Cu—Ni solid solution layers 26 and 36 in which Ni is solid-dissolved in the Cu matrix are formed on the layers 22 and 32. The Al—Ni intermetallic compound layers 25 and 35 and the Cu—Ni solid solution layers 26 and 36 are directly laminated.

Examples of the intermetallic compound contained in the Al-Ni intermetallic compound layers 25 and 35 include Al ₃ Ni and Al ₃ Ni ₂ .
The thickness of the Al—Ni intermetallic compound layers 25 and 35 is within the range of 0.02 mm or more and 0.1 mm or less.

In the Cu—Ni solid solution layers 26 and 36, the Ni concentration may be inclined in the thickness direction. The Ni concentration in the Cu—Ni solid solution layers 26 and 36 is, for example, in the range of 0.1 mass% or more and 50 mass% or less.
The thickness of the Cu—Ni solid solution layers 26 and 36 is within the range of 0.001 mm or more and 0.02 mm or less.

Next, a method of manufacturing the insulated circuit board 10 according to the present embodiment will be described with reference to FIGS. 3 to 7.

First, as shown in FIG. 4, an aluminum plate 51 to be an aluminum layer 21 is laminated on one surface (upper surface in FIG. 4) of the ceramic substrate 11 via an Al—Si based brazing material foil 58 as a bonding material. Further, a copper plate 52 to be a copper layer 22 is laminated on the copper plate 52 via a nickel material 54. Further, an aluminum plate 61 to be an aluminum layer 31 is laminated on the other surface (lower surface in FIG. 4) of the ceramic substrate 11 via an Al—Si based brazing material foil 68 as a bonding material, and a nickel material is further laminated on the aluminum plate 61. A copper plate 62 to be a copper layer 32 is laminated via 64 (lamination step S01).
As the nickel materials 54 and 64, pure nickel foil having a thickness of 0.01 mm or more and 0.05 mm or less and a purity of 99 mass% or more can be used.

Next, as shown in the temperature pattern diagram of FIG. 5, under vacuum conditions, the above-mentioned laminated body was subjected to 1.0 kgf / cm ² or more and 30 kgf / cm ² or less (0.1 MPa or more and 3.0 MPa or less) in the stacking direction. It is heated in a pressurized state within the range and held in a temperature range of 620 ° C. or higher and 642 ° C. or lower (high temperature holding step S02).

In this high temperature holding step S02, the ceramic substrate 11 and the aluminum plates 51 and 61 are joined, and the aluminum plates 51 and 61 and the nickel materials 54 and 64 and the nickel materials 54 and 64 and the copper plates 52 and 62 are solid-phase diffusion bonded, respectively. .. As a result, as shown in FIG. 6, the aluminum layers 21 and 31 and the copper layers 22 and 32 are formed. Here, as shown in FIG. 6, after the high temperature holding step S02, the nickel layers 24 and 34 remain at the bonding interface between the aluminum layers 21 and 31 and the copper layers 22 and 32, and the nickel layers 24 and 24 remain. The Al—Ni intermetallic compound layers 25 and 35 are formed on the aluminum layers 21 and 31 of 34, and the Cu—Ni solid solution layers 26 and 36 are formed on the copper layers 22 and 32 of the nickel layers 24 and 34.

Here, when the holding temperature in the high temperature holding step S02 is less than 620 ° C., the ceramic substrate 11 and the aluminum plates 51 and 61 are joined, and the aluminum plates 51 and 61 and the nickel materials 54 and 64 (nickel layers 24 and 34) and the nickel material are joined. The solid-phase diffusion bonding between 54,64 (nickel layers 24,34) and the copper plates 52, 62 became insufficient, and the bondability between the ceramic substrate 11 and the aluminum plates 51, 61 and the aluminum plates 51, 61 and the copper plate 52 , 62's bondability is reduced.
When the holding temperature in the high temperature holding step S02 exceeds 642 ° C., a liquid phase is formed between the aluminum plates 51 and 61 and the nickel materials 54 and 64 (nickel layers 24 and 34), and the aluminum plates 51 and 61 are melted. This causes a shape defect.
From the above, in the present embodiment, the holding temperature in the high temperature holding step S02 is set within the range of 620 ° C. or higher and 642 ° C. or lower.
The lower limit of the holding temperature in the high temperature holding step S02 is preferably 630 ° C. or higher, and more preferably 635 ° C. or higher. Further, the upper limit of the holding temperature in the high temperature holding step S02 is preferably 640 ° C. or lower.

Further, the holding time in the high temperature holding step S02 is preferably in the range of 5 minutes or more and 30 minutes or less.
Here, the lower limit of the holding time in the high temperature holding step S02 is preferably 10 minutes or more, and more preferably 20 minutes or more.

After this high temperature holding step S02, as shown in the temperature pattern diagram of FIG. 5, the above-mentioned laminate was placed in the stacking direction at 1.0 kgf / cm ² or more and 30 kgf / cm ² or less (0.1 MPa or more and 3.0 MPa or less). In a state of being pressurized within the above range, the temperature is maintained at 500 ° C. or higher and below the eutectic temperature of aluminum and copper (low temperature holding step S03).

In this low temperature holding step S03, the Ni atoms of the nickel layers 24 and 34 are diffused to eliminate the nickel layers 24 and 34. That is, in this low temperature holding step S03, as shown in FIG. 7, the Al—Ni metal compound layers 25 and 35 grow by diffusing the Ni atoms of the nickel layers 24 and 34 toward the aluminum layers 21 and 31. By diffusing the Ni atoms of the nickel layers 24 and 34 toward the copper layers 22 and 32, the Cu—Ni solid solution layers 26 and 36 grow, so that the nickel layers 24 and 34 disappear and the Al—Ni metal compound layer 25, 35 and Cu—Ni solid solution layers 26, 36 will be directly laminated. Here, the nickel layers 24 and 34 are layers having a Ni concentration of 99 mass% or more.

Here, if the holding temperature in the low temperature holding step S03 is less than 500 ° C., the Ni atoms of the nickel layers 24 and 34 cannot be sufficiently diffused, the nickel layers 24 and 34 remain, and the thermal resistance becomes high.
Further, when the holding temperature in the low temperature holding step S03 becomes equal to or higher than the eutectic temperature of aluminum and copper, the nickel layers 24 and 34 disappear and the liquid phase occurs when the aluminum layers 21 and 31 and the copper layers 22 and 32 come into direct contact with each other. Will occur, and shape defects will occur.
From the above, in the present embodiment, the holding temperature in the low temperature holding step S03 is set to a range of 500 ° C. or higher and lower than the eutectic temperature of aluminum and copper.
The lower limit of the holding temperature in the low temperature holding step S03 is preferably 520 ° C. or higher, and more preferably 540 ° C. or higher.

Further, the holding time in the low temperature holding step S03 may be longer than the time required for the nickel layers 24 and 34 to disappear, and is preferably set appropriately according to the thickness of the nickel layers 24 and 34.
In the present embodiment, the thickness of the nickel layers 24 and 34 is within the range of 0.01 mm or more and 0.05 mm or less, so that the holding time in the low temperature holding step S03 is, for example, within the range of 30 minutes or more and 300 minutes or less. Is preferable.

By the above steps, the insulated circuit board 10 according to the present embodiment is manufactured.

Next, the heat sink 41 is laminated on the metal layer 30 of the insulating circuit board 10 via a solder material, and solder-bonded in the reduction furnace (heat sink bonding step S04).
Next, the power semiconductor element 3 is laminated on one surface of the circuit layer 20 (the surface of the copper layer 22) via a solder material, and solder-bonded in the reduction furnace (power semiconductor element bonding step S05).
As described above, the power module 1 according to the present embodiment is manufactured.

In the method for manufacturing the insulated circuit board 10 according to the present embodiment having the above configuration, the ceramics substrate 11 and the aluminum plates 51 and 61 are laminated via the brazing foils 58 and 68, and the aluminum plate 51 is laminated. , 61 and copper plates 52, 62 are laminated via nickel materials 54, 64, and this is pressurized in the lamination direction to be heated and held in a temperature range of 620 ° C. or higher and 642 ° C. or lower. Therefore, the ceramic substrate 11 and the aluminum plates 51 and 61 can be reliably joined to form the aluminum layers 21 and 31, and the aluminum plates 51 and 61 and the nickel materials 54 and 64 and the nickel material 54, The copper layers 22 and 32 and the nickel layers 24 and 34 can be formed by reliably joining the 64 and the copper plates 52 and 62 by solid-phase diffusion bonding, respectively. Further, due to the nickel layers 24 and 34, Al and Cu do not come into direct contact with each other, and the formation of a liquid phase can be suppressed.

Then, after the high temperature holding step S02, the low temperature holding step S03 for holding the nickel layers 24 and 34 in a temperature range lower than the eutectic temperature of aluminum and copper at 500 ° C. or higher is carried out. The nickel layers 24 and 34 can be eliminated by diffusing them on the 31 side and the copper layers 22 and 32. Therefore, the insulating circuit board 10 having excellent heat dissipation characteristics can be manufactured without the nickel layers 24 and 34 serving as thermal resistance at the junction interface between the aluminum layers 21 and 31 and the copper layers 22 and 32. Further, since the upper limit of the temperature in the low temperature holding step S03 is lower than the eutectic temperature of aluminum and copper, the nickel layers 24 and 34 disappear in the low temperature holding step S03, and the metal-containing compound containing Al and the metal containing Cu Even when the inter-compounds come into direct contact with each other, it is possible to suppress the formation of a liquid phase at the bonding interface between the aluminum layers 21 and 31 and the copper layers 22 and 32, and prevent the circuit layer 20 and the metal layer 30 from having a defective shape. Can be done.

Further, in the insulating circuit board 10 of the present embodiment, the circuit layer 20 formed on one surface of the ceramic substrate 11 and the metal layer 30 formed on the other surface of the ceramic substrate 11 are the aluminum layers 21, 31. The structure is such that the copper layers 22 and 32 are laminated, and the Al—Ni metal-metal compound formed on the aluminum layers 21 and 31 at the bonding interface between the aluminum layers 21 and 31 and the copper layers 22 and 32. Since the layers 25 and 35 and the Cu—Ni solid solution layers 26 and 36 formed on the copper layers 22 and 32 are directly laminated, the nickel layers 24 and 34 that serve as thermal resistance do not remain. Has excellent heat dissipation characteristics.

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

Further, like the power module 101 and the insulating circuit board 110 shown in FIG. 8, only the circuit layer 120 formed on one surface (upper surface in FIG. 8) of the ceramics substrate 111 is a copper member (copper) made of copper or a copper alloy. The layer 122) and an aluminum member (aluminum layer 121) made of aluminum or an aluminum alloy may be laminated. In this case, the materials of the metal layer 130 and the heat sink 141 are not particularly limited.
Alternatively, like the power module 201 and the insulating circuit substrate 210 shown in FIG. 9, only the metal layer 230 formed on the other surface (lower surface in FIG. 9) of the ceramic substrate 211 is a copper member (copper) made of copper or a copper alloy. The layer 232) and an aluminum member (aluminum layer 231) made of aluminum or an aluminum alloy may be laminated. In this case, the materials of the circuit layer 220 and the heat sink 241 are not particularly limited.

The results of the confirmation experiment conducted to confirm the effect of the present invention will be described below.
Aluminum (thickness 10 μm) having a purity of 99 mass% or more is formed on one surface and the other surface of a ceramic substrate made of AlN (40 mm × 40 mm × 0.635 mmt) via a brazing foil (thickness 10 μm) made of Al-7 mass% Si alloy. Aluminum plate (37 mm x 37 mm x 0.6 mmt) made of 2N aluminum), nickel material (37 mm x 37 mm, thickness is shown in Table 1), and copper plate made of oxygen-free copper (37 mm x 37 mm x 0.3 mmt) in order. It was laminated to obtain a laminated body.

Then, under vacuum conditions (5 × 10 ^-4 Pa), the above-mentioned laminated body is heated in a state of being pressurized at the pressure shown in Table 1 in the stacking direction, and the high temperature holding step and the low temperature holding step under the conditions shown in Table 1 are performed. To produce the insulated circuit boards of the examples of the present invention and the comparative examples having a circuit layer and a metal layer. As a conventional example, an insulated circuit board was manufactured without performing a low temperature holding step.

With respect to the insulating circuit board obtained as described above, the bonding ratio between the ceramic substrate and the aluminum layer, the thermal resistance in the stacking direction, and the presence or absence of the nickel layer at the bonding interface between the aluminum layer and the copper layer were evaluated.

(Joining rate)
The bonding rate is evaluated by using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.) for the bonding rate at the interface between the ceramic substrate and the aluminum layer of the insulating circuit board, and the bonding rate is calculated from the following formula. Calculated.
Here, the initial bonding area is the area to be bonded before bonding, that is, the area of the circuit layer and the metal layer (37 mm × 37 mm) in this embodiment.
(Joining rate) = {(Initial bonding area)-(Peeling area)} / (Initial bonding area)
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.

(Thermal resistance)
A heat source chip (1.0 mm × 1.0 mm) was soldered to the surface on one side of the insulating circuit board. Then, the thermal resistance was calculated by the following formula from the temperature of the heat source chip and the ambient temperature (25 ° C.) when the input power was 1 W.
(Heat source chip temperature-Atmospheric temperature) / Input power

(Presence / absence of nickel layer)
The cross section of the circuit layer of the obtained insulated circuit board was subjected to line analysis of the Ni concentration in the stacking direction from the aluminum layer to the copper layer using EPMA (JXA-8530F manufactured by JEOL Ltd.), and the Ni concentration was 99 mass%. When the above-mentioned parts existed, the Ni layer was evaluated as "Yes".

In the conventional example in which the low temperature holding step was not provided and in Comparative Example 1 in which the holding temperature of the low temperature holding step was low, the nickel layer remained and the thermal resistance was high. In Comparative Example 2 in which the holding temperature of the high temperature holding step was high and Comparative Example 3 in which the holding temperature of the low temperature holding step was high, the aluminum layer was melted and the shape of the circuit layer and the metal layer was defective. Therefore, in Comparative Example 2 and Comparative Example 3, "presence or absence of nickel layer", "bonding ratio", and "thermal resistance" could not be measured. In Comparative Example 4 in which the holding temperature of the high temperature holding step was lowered, the bonding ratio between the ceramic substrate and the aluminum layer was lowered.
On the other hand, in Examples 1 to 11 of the present invention in which the holding temperature of the high temperature holding step and the holding temperature of the low temperature holding step are within the range of the present invention, the nickel layer disappears, the thermal resistance is lowered, and the ceramic substrate and aluminum are used. An insulated circuit board with well-bonded layers could be obtained.

1 Power module 3 Power semiconductor element 10 Insulated circuit board 11 Ceramic substrate 20 Circuit layer 30 Metal layer 21, 31 Aluminum layer (aluminum member)
22, 32 Copper layer (copper member)
24,34 Nickel layer 25,35 Al-Ni intermetallic compound layer 26,36 Cu-Ni solid solution layer 54, 64 Nickel material

Claims (9)

A method for manufacturing a bonded body including a ceramic member, an aluminum member made of aluminum or an aluminum alloy bonded to the ceramic member, and a copper member made of copper or a copper alloy bonded to the aluminum member.
A laminating step of laminating the ceramic member and the aluminum member via a joining material, and laminating the aluminum member and the copper member via a nickel layer.
A high-temperature holding step of heating the laminated ceramic member, the aluminum member, and the copper member in a pressurized state in the laminating direction and holding the laminated member in a temperature range of 620 ° C. or higher and 642 ° C. or lower.
After this high temperature holding step, a low temperature holding step of holding at 500 ° C. or higher and lower than the eutectic temperature of aluminum and copper is provided.
In the high temperature holding step, the ceramic member and the aluminum member are joined, and the aluminum member and the nickel layer and the nickel layer and the copper member are solid-phase diffusion bonded, respectively.
A method for producing a bonded body, which comprises diffusing Ni atoms in the nickel layer to eliminate the nickel layer in the low temperature holding step. The first aspect of the invention, wherein in the laminating step, the thickness of the nickel layer disposed between the aluminum member and the copper member is within the range of 0.01 mm or more and 0.05 mm or less. Manufacturing method of the bonded body. A method for manufacturing an insulated circuit board in which a circuit layer in which an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy are laminated is formed on one surface of a ceramics substrate.
A method for manufacturing an insulated circuit board, characterized in that the circuit layer is formed by the method for manufacturing a bonded body according to claim 1 or 2. A circuit layer is arranged on one surface of the ceramics substrate, and a metal layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on the other surface of the ceramics substrate. This is a method for manufacturing an insulated circuit board.
A method for manufacturing an insulated circuit board, characterized in that the metal layer is formed by the method for manufacturing a bonded body according to claim 1 or 2. A circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of the ceramics substrate, and aluminum or an aluminum alloy is formed on the other surface of the ceramics substrate. A method for manufacturing an insulated circuit substrate in which a metal layer formed by laminating an aluminum layer made of copper or a copper layer made of copper or a copper alloy is formed.
A method for manufacturing an insulated circuit board, characterized in that the circuit layer and the metal layer are formed by the method for manufacturing a bonded body according to claim 1 or 2. A bonded body including a ceramics member, an aluminum member made of aluminum or an aluminum alloy bonded to the ceramics member, and a copper member made of copper or a copper alloy bonded to the aluminum member.
At the bonding interface between the aluminum member and the copper member, an Al—Ni intermetallic compound layer containing an intermetallic compound of Al and Ni is formed on the aluminum member side, and a Cu matrix is formed on the copper member side. A bonded body characterized in that a Cu—Ni solid solution layer in which Ni is solid-dissolved is formed therein, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated. An insulating circuit board in which a circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of a ceramics substrate.
At the bonding interface between the aluminum layer and the copper layer, an Al—Ni intermetallic compound layer containing an intermetallic compound of Al and Ni is formed on the aluminum layer side, and a Cu matrix is formed on the copper layer side. An insulating circuit substrate characterized in that a Cu—Ni solid solution layer in which Ni is solid-dissolved is formed therein, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated. A circuit layer is arranged on one surface of the ceramics substrate, and a metal layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on the other surface of the ceramics substrate. Insulated circuit board
At the bonding interface between the aluminum layer and the copper layer, an Al—Ni intermetallic compound layer containing an intermetallic compound of Al and Ni is formed on the aluminum layer side, and a Cu matrix is formed on the copper layer side. An insulating circuit substrate characterized in that a Cu—Ni solid solution layer in which Ni is solid-dissolved is formed therein, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated. A circuit layer formed by laminating an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy is formed on one surface of the ceramics substrate, and aluminum or an aluminum alloy is formed on the other surface of the ceramics substrate. An insulating circuit board having a metal layer formed by laminating an aluminum layer made of copper or a copper layer made of copper or a copper alloy.
At the bonding interface between the aluminum layer and the copper layer, an Al—Ni intermetallic compound layer containing an intermetallic compound of Al and Ni is formed on the aluminum layer side, and a Cu matrix is formed on the copper layer side. An insulating circuit substrate characterized in that a Cu—Ni solid solution layer in which Ni is solid-dissolved is formed therein, and the Al—Ni intermetallic compound layer and the Cu—Ni solid solution layer are directly laminated.

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