JP6645281B2 - Method for producing ceramic / aluminum joined body and method for producing substrate for power module - Google Patents

Description

  The present invention relates to a method of manufacturing a ceramic / aluminum joined body in which a ceramic member and an aluminum member are joined, and a method of manufacturing a power module substrate including a ceramic substrate and an aluminum plate joined to the ceramic substrate. is there.

A semiconductor device such as an LED or a power module has a structure in which a semiconductor element is bonded on a circuit layer made of a conductive material.
A power semiconductor element for large power control used for controlling a wind power generation, an electric vehicle, a hybrid vehicle, and the like generates a large amount of heat, and therefore, as a substrate on which it is mounted, for example, AlN (aluminum nitride), Al _2. Description of the Related Art Power module substrates including a ceramic substrate made of ₂ O ₃ (alumina) and a circuit layer formed by bonding a metal plate having excellent conductivity to one surface of the ceramic substrate have been widely used. Used. As the power module substrate, there is also provided a substrate in which a metal plate is bonded to the other surface of a ceramic substrate to form a metal layer.

For example, in Patent Literature 1, an aluminum plate serving as a circuit layer is joined to one surface of a ceramic substrate made of AlN (aluminum nitride) via an Al-Si brazing material, and a metal substrate is attached to the other surface of the ceramic substrate. There has been proposed a power module substrate in which an aluminum plate serving as a layer is joined via an Al-Si brazing material.
In such a power module substrate, a semiconductor element as a power element is mounted on a circuit layer via a solder layer, and is used as a power module. Further, a heat sink made of aluminum or copper may be joined to the metal layer side.

  Patent Document 2 discloses that an aluminum member having a purity of 99.5% or more is brought into contact with at least one surface of a ceramic substrate and heated to a temperature of 620 ° C. to 650 ° C. in an inert gas. There has been proposed a technique of directly bonding a ceramic substrate to a ceramic substrate. In Patent Document 2, it is described that the aluminum member is not pressed toward the ceramic substrate or is pressed at 1000 Pa or less.

International Publication No. WO 03/090277 Japanese Patent No. 3935037

By the way, as described in Patent Document 1, when a ceramic substrate and an aluminum plate are joined by using a brazing material, a large amount of liquid phase is generated at a joint interface between the ceramic substrate and the aluminum plate, and the solder bumps are formed. Surface abnormalities such as wax stains may occur.
In addition, when a heat sink or the like is further joined by using a flux after brazing the ceramic substrate and the aluminum plate, there is a problem that the brazing material is re-melted and is easily affected by flux erosion.
Furthermore, a layer having strong anisotropy due to the brazing material is formed at the bonding interface between the ceramic substrate and the aluminum plate, and there is a possibility that the bonding reliability may be reduced.

  Further, as described in Patent Literature 2, when an aluminum plate is directly joined to a ceramic substrate, the load in the laminating direction is low, and thus there is a possibility that the joining may be insufficient during a thermal cycle load. As described above, since the reliability of the cooling / heating cycle is low, it cannot be applied to a power module substrate or the like.

  The present invention has been made in view of the above circumstances, and provides a ceramic / aluminum joined body that can directly join a ceramic member and an aluminum member without using a brazing material and that has excellent thermal cycle reliability. It is an object of the present invention to provide a method of manufacturing a ceramics / aluminum joined body and a method of manufacturing a power module substrate, which are capable of performing the method.

In order to solve the above problems and achieve the above object, a method for manufacturing a ceramic / aluminum joined body according to the present invention is directed to a ceramic / aluminum joined body formed by joining a ceramic member and an aluminum member made of a eutectic aluminum alloy. / A method for manufacturing an aluminum joined body, comprising: a laminating step of laminating the ceramic member and the aluminum member; and a load of 0.29 MPa to 1.47 MPa in the laminating direction of the laminated ceramic member and the aluminum member. And heating the aluminum alloy at a holding temperature equal to or higher than the eutectic temperature of the aluminum alloy and lower than the liquidus temperature to form a solid-liquid coexistence region at a bonding interface between the ceramic member and the aluminum member. By solidifying the liquid coexistence region, the ceramic member and the aluminum member And if solidified step, and wherein the aluminum alloy is the eutectic temperature of 450 ° C. or higher and the liquidus temperature is characterized in that there is a 640 ° C. or higher.

According to the method for manufacturing a ceramics / aluminum joined body having this configuration, the ceramic member and the aluminum member are maintained at a holding temperature equal to or higher than the eutectic temperature of the aluminum alloy and lower than the liquidus temperature to form a solid-liquid coexistence region. And the liquid phase is not generated in a large amount, and there is no possibility that surface abnormalities such as bumps and stains will occur.
In addition, since no brazing material is used, a layer having strong anisotropy due to the brazing material is not formed at the joining interface between the ceramic member and the aluminum member, and the joining reliability is excellent.
Further, at the time of joining, since a load of 0.29 MPa to 1.47 MPa is applied to the laminated ceramic member and the aluminum member in the laminating direction, the ceramic member and the aluminum member are securely joined. As a result, it is possible to obtain a ceramic / aluminum joined body having excellent thermal cycle reliability.
Since the eutectic temperature of the aluminum alloy is 450 ° C. or higher, a liquid phase is surely generated at a temperature at which the interfacial reaction between the ceramic and the aluminum member proceeds sufficiently to form a strong ceramic / aluminum joint. Obtainable. In addition, since the liquidus temperature of the aluminum alloy is 640 ° C. or higher, it is possible to reliably suppress deformation and surface deterioration of the aluminum member due to excessive generation of the liquid phase.

Here, in the method for manufacturing a ceramics / aluminum joined body of the present invention, the aluminum alloy preferably contains one or more selected from Si, Cu, Ag, and Mg as additional elements. .
In this case, since the eutectic temperature of the aluminum alloy is reduced by containing elements such as Si, Cu, Ag, and Mg as additional elements, it is possible to join the ceramic member and the aluminum member under a low temperature condition. Become.

  The method for manufacturing a power module substrate of the present invention is a method for manufacturing a power module substrate including a ceramic substrate and an aluminum plate bonded to the ceramic substrate, wherein the aluminum plate is made of an aluminum alloy, The present invention is characterized in that the aluminum plate and the ceramic substrate are joined by the above-described method for producing a ceramic / aluminum joined body.

  In a power module substrate, a circuit layer or a metal layer is formed by bonding an aluminum plate to one surface or the other surface of a ceramic substrate. Here, the aluminum plate constituting the circuit layer or the metal layer is bonded to the ceramic substrate by the above-described method for manufacturing a ceramic / aluminum bonded body, whereby a power module substrate excellent in thermal cycle reliability can be obtained. . Further, surface deterioration of the circuit layer or the metal layer can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, manufacture of a ceramics / aluminum joined body which can join a ceramics member and an aluminum member directly without a brazing material, and can obtain a ceramics / aluminum joined body excellent in thermal cycle reliability. It is possible to provide a method and a method for manufacturing a power module substrate.

1 is a schematic explanatory view of a power module using a power module substrate manufactured by a method for manufacturing a power module substrate according to an embodiment of the present invention. It is a flow figure showing the manufacturing method of the substrate for power modules which is an embodiment of the present invention. It is an explanatory view showing a manufacturing method of a substrate for power modules which is an embodiment of the present invention. It is explanatory drawing which shows the joining method of the board for power modules which is embodiment of this invention, and a heat sink. FIG. 5 is a schematic explanatory view of a power module using another power module substrate manufactured by the method for manufacturing a power module substrate according to the embodiment of the present invention. It is a binary phase diagram of Al and Si.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The ceramic / aluminum joined body according to the present embodiment is a power module including a ceramic substrate 11 as a ceramic member, a circuit layer 12 formed by bonding an aluminum plate 22 as an aluminum member, and a metal layer 13 formed by bonding an aluminum plate 23. Substrate 10.

FIG. 1 shows a power module 1 using a power module substrate 10 according to an embodiment of the present invention.
The power module 1 includes a power module substrate 10 on which a circuit layer 12 and a metal layer 13 are provided, and a semiconductor element joined to one surface (the upper surface in FIG. 1) of the circuit layer 12 via a solder layer 2. 3 and a heat sink 40 joined to the other surface (the lower surface in FIG. 1) of the metal layer 13.
Here, the solder layer 2 is, for example, a Sn-Ag-based, Sn-In-based, or Sn-Ag-Cu-based solder material. In this embodiment, a Ni plating layer (not shown) is provided between the circuit layer 12 and the solder layer 2.

The power module substrate 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 ceramic substrate 11 on the other surface (lower surface in FIG. 1). And a metal layer 13 provided.
The ceramic substrate 11 serves to prevent electrical connection between the circuit layer 12 and the metal layer 13, and is made of AlN (aluminum nitride) having high insulation in the present embodiment. The thickness of the ceramic substrate 11 is set in the range of 0.2 to 1.5 mm, and is set to 0.635 mm in the present embodiment.

The circuit layer 12 is formed by joining a conductive metal plate to one surface of the ceramic substrate 11.
In the present embodiment, as shown in FIG. 3, the circuit layer 12 is formed by joining an aluminum plate 22 made of a rolled plate of an eutectic aluminum alloy to the ceramic substrate 11. A circuit pattern is formed on the circuit layer 12, and one surface thereof (the upper surface in FIG. 1) is a mounting surface on which the semiconductor element 3 is mounted. Here, the thickness of the circuit layer 12 (the aluminum plate 22) is set within a range of 0.01 mm or more and less than 1 mm, and is set to 0.4 mm in the present embodiment. Note that the thickness of the circuit layer 12 is preferably 0.05 mm or more and less than 0.6 mm, but is not limited thereto.
Note that the circuit layer 12 preferably has a conductivity of 45% IACS or more. Further, the Vickers hardness is preferably 70 Hv or less.

The metal layer 13 is formed by joining a metal plate having excellent thermal conductivity to the other surface of the ceramic substrate 11.
In the present embodiment, as shown in FIG. 3, the metal layer 13 is formed by joining an aluminum plate 23 made of a rolled aluminum alloy plate to the ceramic substrate 11. Here, the thickness of the metal layer 13 (aluminum plate 23) is set within a range of 0.01 mm or more and less than 3 mm, and is set to 0.04 mm in the present embodiment. The thickness of the metal layer 13 is preferably 0.05 mm or more and less than 2 mm, but is not limited thereto.

Here, the aluminum alloy constituting the circuit layer 12 (aluminum plate 22) and the metal layer 13 (aluminum plate 23) contains one or more selected from Si, Cu, Ag, and Mg as additional elements. Is preferred.
Preferably, the eutectic temperature of the aluminum alloy is 530 ° C. or higher, and the liquidus temperature is 640 ° C. or higher.

In the case of an Al-Si alloy containing Si as an additive element, the content of Si is preferably in the range of 0.3 mass% to 2.4 mass%.
In the case of an Al-Cu alloy containing Cu as an additive element, the content of Cu is preferably in the range of 0.7 mass% or more and 7.0 mass% or less.
In the case of an Al-Ag alloy containing Ag as an additional element, the Ag content is preferably in a range of 3.1 mass% to 15.9 mass%.
In the case of an Al-Mg alloy containing Mg as an additional element, the content of Mg is preferably in a range of 0.6 mass% to 4.5 mass%.

In the case of an Al-Si-Mg alloy containing Si and Mg as additional elements, the content of Si is set within a range of 0.3 mass% to 0.8 mass%, and the content of Mg is set to 0.5 mass% to 1 mass%. It is preferable to be within the range of 0.2 mass% or less.
In the case of an Al-Cu-Ag alloy containing Cu and Ag as additional elements, the Cu content is in the range of 0.7 mass% to 2.0 mass%, and the Ag content is 2.5 mass% to 4 mass%. It is preferable to be within the range of 0.5 mass% or less.

The heat sink 40 is for cooling the power module substrate 10 described above. As shown in FIG. 1, the heat sink 40 according to the present embodiment is a heat radiating plate made of aluminum or an aluminum alloy.
In this embodiment, the heat sink 40 and the power module substrate 10 are joined by brazing using a flux composed mainly of KAlF _4.

  Next, a method for manufacturing the power module substrate 10 and the method for manufacturing the power module 1 according to the above-described embodiment will be described with reference to FIGS.

(Circuit layer and metal layer forming step S01)
First, the aluminum plates 22 and 23 are joined to the ceramic substrate 11 to manufacture the power module substrate 10 according to the present embodiment.
The circuit layer and metal layer forming step S01 includes a laminating step S11, a heating step S12, and a solidifying step S13 to be described later.

  In the laminating step S11, as shown in FIG. 3, an aluminum plate 22 is laminated on one surface (upper surface in FIG. 3) of the ceramic substrate 11, and an aluminum plate 22 is laminated on the other surface (lower surface in FIG. 3) of the ceramic substrate 11. The plates 23 are stacked.

  Next, in the heating step S12, a load of 0.29 MPa or more and 1.47 MPa or less is applied to the laminated ceramics substrate 11 and the aluminum plates 22 and 23 in the laminating direction, and the aluminum alloy forming the aluminum plates 22 and 23 is formed. Is held at a holding temperature not lower than the eutectic temperature and lower than the liquidus temperature, and a solid-liquid coexisting region is formed at the joint interface between the ceramic substrate 11 and the aluminum plates 22 and 23.

Here, when the load when pressing in the laminating direction is less than 0.29 MPa, the ceramic substrate 11 and the aluminum plates 22 and 23 do not sufficiently adhere to each other, and there is a possibility that bonding may be insufficient. On the other hand, when the load when pressing in the laminating direction exceeds 1.47 MPa, the shape of the aluminum plate may not be able to be maintained. For this reason, in this embodiment, the load at the time of pressing in the laminating direction is set in the range of 0.29 MPa to 1.47 MPa.
In order to further bring the ceramic substrate 11 and the aluminum plates 22 and 23 into close contact with each other, the lower limit of the load when pressing in the laminating direction is preferably 0.49 MPa or more, more preferably 0.79 MPa or more. preferable. Further, in order to surely maintain the shape of the aluminum plate, the upper limit of the load when pressing in the laminating direction is preferably 1.2 MPa or less, and more preferably 0.98 MPa or less.

  If the holding temperature is lower than the eutectic temperature of the aluminum alloy forming the aluminum plates 22 and 23, no liquid phase is formed and the ceramic substrate 11 and the aluminum plates 22 and 23 cannot be joined. On the other hand, when the holding temperature is equal to or higher than the liquidus temperature of the aluminum alloy forming the aluminum plates 22 and 23, the aluminum plates 22 and 23 may be melted and the shape may not be maintained. For this reason, in the present embodiment, the holding temperature is set in a range from the eutectic temperature of the aluminum alloy forming the aluminum plates 22 and 23 to the liquidus temperature.

  For example, when Al-1.9 mass% Si is used as an aluminum alloy constituting the circuit layer 12 (aluminum plate 22) and the metal layer 13 (aluminum plate 23), as shown in the state diagram of FIG. The temperature is 577 ° C and the liquidus temperature is 648 ° C. Therefore, when Al-1.9 mass% Si is used, the holding temperature is set in the range of 577 ° C or more and less than 648 ° C.

  In order to securely join the ceramic substrate 11 and the aluminum plates 22 and 23, the lower limit of the holding temperature is preferably set to be equal to or higher than the eutectic temperature of the aluminum alloy + 5 ° C. More preferably, Further, in order to surely maintain the shape of the aluminum plate, the upper limit of the holding temperature is preferably set to a liquidus temperature of the aluminum alloy of −5 ° C. or less, and is preferably set to a liquidus temperature of −10 ° C. or less. More preferred.

Next, in the solidification step S13, the ceramic substrate 11 and the aluminum plate 22 and the aluminum plate 23 are solidified by solidifying solid-liquid coexistence regions formed at the interface between the aluminum plates 22 and 23 and the ceramic substrate 11, respectively. Join.
Thus, the power module substrate 10 in which the circuit layer 12 and the metal layer 13 are formed on the ceramic substrate 11 is manufactured.

(Heat sink bonding step S02)
Next, as shown in FIG. 4, a heat sink 40 is bonded to the other surface of the metal layer 13 of the power module substrate 10.
More specifically, between the metal layer 13 and the heat sink 40 of the power module substrate 10, the Al-Si based brazing filler metal foil 27, is interposed between the flux (not shown) mainly composed of KAlF _4.

Next, in a state where the laminated power module substrate 10 and the heat sink 40 are pressurized (pressure 0 to 10 kgf / cm ² ) in the laminating direction, the power module substrate 10 and the heat sink 40 are charged into an atmosphere heating furnace and heated, so that the metal layer 13 and the heat sink A molten metal region is formed between the molten metal region and the molten metal region. Then, by solidifying the above-described molten metal region, the metal layer 13 of the power module substrate 10 and the heat sink 40 are joined. At this time, oxide films are formed on the surfaces of the metal layer 13 and the heat sink 40, and these oxide films are removed by the above-mentioned flux. At this time, the flux component is liquefied and vaporized and moves to the ceramic substrate 11 side.

(Semiconductor element bonding step S03)
Further, the semiconductor element 3 is joined to one surface of the circuit layer 12 via the first solder layer 2. Thereby, the power module 1 according to the present embodiment is produced.

  According to the method for manufacturing the power module substrate 10 of the present embodiment having the above-described configuration, in the heating step S12, the aluminum alloy of the circuit layer 12 and the metal layer 13 (the aluminum plates 22 and 23) is formed. Holding at a holding temperature not lower than the eutectic temperature and lower than the liquidus temperature to form a solid-liquid coexistence region and joining the ceramic substrate 11 and the aluminum plates 22 and 23, a large amount of liquid phase is generated at the joining interface. And there is no possibility that surface abnormalities such as wax bumps and wax stains will occur.

In addition, according to the method of manufacturing the power module substrate 10 of the present embodiment, since no brazing material is used, the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13 causes a difference caused by the brazing material. No highly anisotropic layer is formed, and the bonding reliability is excellent.
Further, even when a flux is used in the heat sink bonding step S02, there is no possibility that the reliability of the bonding between the ceramic substrate 11, the circuit layer 12, and the metal layer 13 is reduced by the influence of the flux.
Also, at the time of joining, a load of 0.29 MPa or more and 1.47 MPa or less is applied to the laminated ceramics substrate 11 and aluminum plates 22 and 23 in the laminating direction. It is possible to manufacture the power module substrate 10 that is securely joined and has excellent thermal cycle reliability.

  In the present embodiment, the aluminum alloy forming the circuit layer 12 and the metal layer 13 (the aluminum plates 22 and 23) contains one or more selected from Si, Cu, Ag, and Mg as additional elements. Therefore, the eutectic temperature of the aluminum alloy is lowered, and the ceramic substrate 11 and the aluminum plates 22 and 23 can be joined under a low temperature condition.

Furthermore, in this embodiment, since the eutectic temperature is set to 530 ° C. or higher as the aluminum alloy constituting the circuit layer 12 and the metal layer 13 (the aluminum plates 22 and 23), the ceramic substrate 11 and the aluminum By reliably generating a liquid phase at a temperature at which the interfacial reaction between the plates 22 and 23 proceeds sufficiently, a strong power module substrate 10 can be obtained.
Further, since an aluminum alloy having a liquidus temperature of 640 ° C. or higher is used as an aluminum alloy constituting the circuit layer 12 and the metal layer 13 (aluminum plates 22 and 23), the aluminum plate due to excessive generation of a liquid phase is used. Deformation and surface alteration of 22, 23 can be reliably suppressed.

As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and can be appropriately changed without departing from the technical idea of the present invention.
For example, in the present embodiment, the power module substrate has been described as an example. However, the present invention is not limited to this, and a ceramic / aluminum joined body obtained by joining a ceramic member and an aluminum member made of an aluminum alloy. Should be fine.

Further, in the present embodiment, the circuit layer and the metal layer are described as being formed by joining an aluminum plate made of an aluminum alloy.However, the present invention is not limited to this, and any one of the circuit layer and the metal layer may be used. One may be made of an aluminum plate made of an aluminum alloy.
Specifically, when the metal layer is formed of an aluminum plate made of an aluminum alloy, the circuit layer is made of an aluminum plate made of 4N aluminum having a purity of 99.99 mass% or more, a copper plate made of copper or a copper alloy, It may be composed of a laminate of aluminum and copper. When the circuit layer is made of an aluminum plate made of an aluminum alloy, the metal layer is made of another metal or a composite material such as an aluminum plate made of 4N aluminum having a purity of 99.99 mass% or more. Is also good.

  In the present embodiment, the circuit layer 12 and the metal layer 13 are described as being formed on one surface and the other surface of the ceramic substrate 11, respectively. However, as shown in FIG. 5, the metal layer is formed. Instead, the power module substrate 110 in which only the circuit layer 12 is formed on one surface of the ceramic substrate 11 may be used. In the power module 101 shown in FIG. 5, a heat sink 40 is bonded to a surface of the power module substrate 110 opposite to the circuit layer 12.

In this embodiment, the ceramic substrate 11 has been described by taking aluminum nitride (AlN) as an example. However, the present invention is not limited to this, and alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄₎ ) And other ceramics.
Furthermore, although it has been described that the Ni plating layer is formed on the surface where the circuit layer and the metal layer are to be soldered, the present invention is not limited to this, and the underlying layer may be formed by other means such as an Ag paste. Good.
Further, the heat sink is not limited to the one exemplified in the present embodiment, and the structure of the heat sink is not particularly limited. For example, a heat sink having a cooling medium flow path formed therein may be used. Further, a heat sink having a radiation fin may be used.

  Furthermore, although it has been described that the circuit layer is formed by bonding an aluminum plate, the present invention is not limited to this, and a small piece of aluminum may be bonded to the surface of the ceramic substrate in a wiring pattern. . In this case, a step of forming a wiring pattern by etching a circuit layer can be omitted.

A confirmation experiment performed to confirm the effectiveness of the present invention will be described.
As an aluminum plate constituting a circuit layer and a metal layer, a rolled plate (48 mm × 58 mm × 0.4 mm thick) of an aluminum alloy having the composition shown in Table 1 was prepared.
Further, a ceramic substrate (50 mm × 60 mm × thickness 0.635 mm) shown in Table 1 was prepared.

In the present invention examples and comparative examples, an aluminum plate was directly laminated on one surface and the other surface of the ceramic substrate, and these were pressed with a load shown in Table 2 in the laminating direction, and under an atmosphere shown in Table 2, and held at the holding temperature and holding time shown in Table 2, then cooled by N ₂ flow. Thus, a power module substrate was manufactured.
In Examples 9 to 11 of the present invention, an aluminum plate was bonded to only one surface of the ceramic substrate.

(Circuit layer deformation)
Regarding the deformation of the circuit layer, the case where the area of the circuit layer has increased by 10% or more with respect to the area of the aluminum plate before joining is indicated by x; the case of 5% or more and less than 10% is indicated by ○; evaluated.

(Initial joining rate)
The joining ratio between the circuit layer and the ceramic substrate was evaluated. Specifically, in the power module substrate, the bonding rate at the interface between the circuit layer and the ceramic substrate was evaluated using an ultrasonic flaw detector (FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.), and calculated from the following equation. Here, the initial bonding area is the area to be bonded before bonding, that is, the area of the circuit layer (48 mm × 58 mm). In the image obtained by binarizing the ultrasonic flaw detection image, peeling is indicated by a white portion in the joint, and the area of this white portion was defined as the peeling area. Table 2 shows the evaluation results.
(Joining rate) = {(initial joining area) − (non-joining area)} / (initial joining area) × 100

(Joint rate after cooling / heating cycle)
The joining rate after the thermal cycle was determined by using a thermal shock tester TSB-51 manufactured by Espec Co., and using a liquid phase (Fluorinert) for the power module substrate with a heat sink in the liquid phase (Fluorinert) at −40 ° C. × 10 minutes ← → 150 ° C. A 3000/10 cycle was performed, and the bonding rate was evaluated in the same manner as described above. Table 2 shows the evaluation results.

(Circuit layer hardness)
On the substrate for the power module before the above-mentioned cooling / heating cycle test, the surface of the circuit layer was measured with a micro Vickers hardness tester in accordance with JIS Z 2244. Table 2 shows the evaluation results.

(Surface deterioration of circuit layer)
In the power module substrate after bonding, the surface of the circuit layer opposite to the ceramic substrate (circuit layer surface) was visually observed, and the occurrence of surface alteration (wax stain) was evaluated according to the following criteria. Table 2 shows the evaluation results.
：: Surface alteration is less than 10% of the area of the circuit layer surface ○: Surface alteration is 10% or more and less than 25% of the area of the circuit layer surface ×: Surface alteration is 25% or more of the area of the circuit layer surface

In Comparative Examples 1 and 3 joined at a temperature lower than the eutectic temperature of the aluminum alloy, no liquid phase was formed, and joining was not possible. In addition, in Comparative Examples 1 and 3, since joining was not possible, the joining ratio after the thermal cycle was not measured.
In Comparative Examples 2 and 4 in which the holding temperature was equal to or higher than the liquidus line, deformation and surface deterioration of the circuit layer occurred.
In Comparative Example 5 in which the load at the time of joining was less than 0.29 MPa, the joining rate after the thermal cycle was low.
In Comparative Example 6 in which the load at the time of joining exceeded 1.47 MPa, deformation of the circuit layer was confirmed.
On the other hand, it was confirmed that the power module substrate of the example of the present invention can obtain a power module substrate having high bonding reliability without deformation and surface deterioration of the circuit layer.

10. Power Module Substrate (Ceramic / Aluminum Joint)
11 Ceramic substrate (ceramic member)
12 circuit layer 13 metal layer 22 aluminum plate (aluminum member)
23 Aluminum plate (aluminum member)

Claims (3)

A method for producing a ceramics / aluminum joined body in which a ceramics member and an aluminum member made of a eutectic aluminum alloy are joined,
A laminating step of laminating the ceramic member and the aluminum member,
A load of 0.29 MPa or more and 1.47 MPa or less is applied in the laminating direction to the stacked ceramic member and the aluminum member, and the ceramic member and the aluminum member are held at a holding temperature of a eutectic temperature or higher and lower than a liquidus temperature of the aluminum alloy, A heating step of forming a solid-liquid coexistence region at a bonding interface between the ceramic member and the aluminum member;
A solidification step of solidifying the solid-liquid coexistence region to join the ceramic member and the aluminum member ,
A method for producing a ceramic / aluminum joined body, wherein the eutectic temperature of the aluminum alloy is 450 ° C. or higher and the liquidus temperature is 640 ° C. or higher .   The method according to claim 1, wherein the aluminum alloy contains one or more selected from Si, Cu, Ag, and Mg as additional elements. A method for manufacturing a power module substrate comprising a ceramic substrate and an aluminum plate bonded to the ceramic substrate,
The aluminum plate is made of an aluminum alloy,
A method for manufacturing a power module substrate, comprising: bonding the aluminum plate and the ceramic substrate by the method for manufacturing a ceramic / aluminum bonded body according to claim 1 .

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