JP2017168509A - Method for manufacturing ceramics/aluminum conjugant and method for manufacturing power module substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a ceramics/aluminum conjugant capable of directly joining a ceramic member and an aluminum member not via a brazing filler material, and obtaining a ceramics/aluminum conjugant with excellent cooling/heating cycle reliability.SOLUTION: A method for manufacturing a ceramics/aluminum conjugant comprises: a laminating step S11 of laminating a ceramic member and an aluminum member made of eutectic aluminum alloy; a heating step S12 of applying a load of not less than 0.29 MPa and not more than 1.47 MPa to the laminated ceramic and aluminum members in a lamination direction, holding the ceramic and aluminum members in a holding temperature of not less than an eutectic temperature of the aluminum alloy and less than a liquidus-line temperature, and forming a solid-liquid coexisting range in a junction interface between the ceramic member and the aluminum member; and a solidifying step S13 of joining the ceramic member and the aluminum member by solidifying the solid-liquid coexisting range.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a ceramic / aluminum bonded body in which a ceramic member and an aluminum member are bonded, and a method for manufacturing a power module substrate including a ceramic substrate and an aluminum plate bonded 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.
In power semiconductor elements for large power control used to control wind power generation, electric vehicles, hybrid vehicles, etc., the amount of heat generated is large. Therefore, for example, AlN (aluminum nitride), Al _2. Description of the Related Art Conventionally, a power module substrate including a ceramic substrate made of ₂ O ₃ (alumina) 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. It is used. As the power joule substrate, a substrate in which a metal layer is formed by bonding a metal plate to the other surface of the ceramic substrate is also provided.

For example, in Patent Document 1, an aluminum plate serving as a circuit layer is bonded to one surface of a ceramic substrate made of AlN (aluminum nitride) via an Al—Si brazing material, and a metal is bonded to the other surface of the ceramic substrate. There has been proposed a power module substrate in which an aluminum plate as a layer is bonded 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 used as a power module. Further, a heat sink made of aluminum or copper may be bonded 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 for directly bonding a ceramic substrate to a ceramic substrate. In Patent Document 2, it is described that the aluminum member is not pressed to the ceramic substrate side or pressed at 1000 Pa or less.

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

By the way, as described in Patent Document 1, when a ceramic substrate and an aluminum plate are bonded using a brazing material, a large amount of a liquid phase is generated at the bonding interface between the ceramic substrate and the aluminum plate, and the solder bump. There was a risk of surface abnormalities such as wax stains.
In addition, after the ceramic substrate and the aluminum plate are brazed, when the heat sink or the like is further joined using a flux, the brazing material is remelted 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 the bonding reliability may be reduced.

  Further, as described in Patent Document 2, when the aluminum plate is directly bonded to the ceramic substrate, the load in the stacking direction is low, so that there is a possibility that the bonding becomes insufficient when the thermal cycle is applied. Thus, since the cooling cycle reliability is low, it could not be applied to a power module substrate or the like.

  The present invention has been made in view of the circumstances described above, and obtains a ceramic / aluminum bonded body capable of directly bonding a ceramic member and an aluminum member without using a brazing material and having excellent thermal cycle reliability. It is an object to provide a method for manufacturing a ceramic / aluminum bonded body and a method for manufacturing a power module substrate.

  In order to solve the above problems and achieve the above object, a method for producing a ceramic / aluminum bonded body according to the present invention is a ceramic in which a ceramic member and an aluminum member made of a eutectic aluminum alloy are bonded. / A manufacturing method of an aluminum joined body, wherein a lamination 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 A heating step of forming a solid-liquid coexistence region at a bonding interface between the ceramic member and the aluminum member, and holding the solid alloy at a bonding temperature between the eutectic temperature of the aluminum alloy and lower than the liquidus temperature, The ceramic member and the aluminum member are solidified by coagulating the liquid coexistence region. It is characterized in that it comprises a multiplexer solidifying step.

According to the method for manufacturing a ceramic / aluminum bonded body having this structure, the ceramic member and the aluminum member are formed by holding a solid-liquid coexistence region by holding at a holding temperature not lower than the eutectic temperature of the aluminum alloy and lower than the liquidus temperature. Are bonded to each other, so that a large amount of liquid phase is not generated, and there is no possibility of occurrence of surface abnormalities such as wax bumps and wax stains.
In addition, since no brazing material is used, a strong anisotropic layer 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.
Furthermore, since the load is 0.29 MPa or more and 1.47 MPa or less in the laminating direction at the time of joining, the ceramic member and the aluminum member are securely joined together. Therefore, it is possible to obtain a ceramic / aluminum bonded body excellent in cooling cycle reliability.

Here, in the method for producing a ceramic / aluminum bonded body according to the present invention, the aluminum alloy preferably contains one or more selected from Si, Cu, Ag, and Mg as additive elements. .
In this case, since the eutectic temperature of the aluminum alloy is lowered by containing elements such as Si, Cu, Ag, and Mg as additive elements, the ceramic member and the aluminum member can be joined under low temperature conditions. Become.

In the method for producing a ceramic / aluminum bonded body according to the present invention, the aluminum alloy preferably has a eutectic temperature of 530 ° C. or higher and a liquidus temperature of 640 ° C. or lower.
In this case, since the eutectic temperature of the aluminum alloy is 530 ° C. or higher, a strong ceramic / aluminum can be obtained by reliably generating a liquid phase at a temperature at which the interface reaction between the ceramic and the aluminum member proceeds sufficiently. A joined body can be obtained. Further, since the liquidus temperature of the aluminum alloy is 640 ° C. or higher, it is possible to reliably suppress deformation and surface alteration of the aluminum member due to excessive generation of the liquid phase.

  The method for producing a power module substrate of the present invention is a method for producing a power module substrate comprising a ceramic substrate and an aluminum plate bonded to the ceramic substrate, wherein the aluminum plate is made of an aluminum alloy, The aluminum plate and the ceramic substrate are bonded together by the above-described method for manufacturing a ceramic / aluminum bonded 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 having excellent cooling cycle reliability can be obtained. . Further, the surface alteration of the circuit layer or the metal layer can be suppressed.

  According to the present invention, a ceramic / aluminum joined body capable of directly joining a ceramic member and an aluminum member without using a brazing material and capable of obtaining a ceramic / aluminum joined body excellent in cooling cycle reliability. It is possible to provide a method and a method for manufacturing a power module substrate.

It is a schematic explanatory drawing of the power module using the power module substrate manufactured by the manufacturing method of the power module substrate which is embodiment of this invention. It is a flowchart which shows the manufacturing method of the board | substrate for power modules which is embodiment of this invention. It is explanatory drawing which shows the manufacturing method of the board | substrate for power modules which is embodiment of this invention. It is explanatory drawing which shows the joining method of the board | substrate for power modules which is embodiment of this invention, and a heat sink. It is a schematic explanatory drawing of the power module using the board | substrate for other power modules manufactured by the manufacturing method of the board | substrate for power modules which is embodiment of this invention. It is a binary phase diagram of Al and Si.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The ceramic / aluminum bonded body according to this embodiment includes a ceramic substrate 11 as a ceramic member, a circuit layer 12 in which an aluminum plate 22 is bonded as an aluminum member, and a metal layer 13 in which an aluminum plate 23 is bonded. The substrate 10 is used.

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 disposed, and a semiconductor element bonded to one surface (upper surface in FIG. 1) of the circuit layer 12 via a solder layer 2. 3 and a heat sink 40 bonded to the other surface (the lower surface in FIG. 1) of the metal layer 13.
Here, the solder layer 2 is made of, for example, a Sn—Ag, Sn—In, or Sn—Ag—Cu solder material. In the present embodiment, a Ni plating layer (not shown) is provided between the circuit layer 12 and the solder layer 2.

The power module substrate 10 has a ceramic substrate 11, a circuit layer 12 disposed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11, and the other surface (lower surface in FIG. 1) of the ceramic substrate 11. And a disposed metal layer 13.
The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13, and is composed of AlN (aluminum nitride) having high insulation in this embodiment. In addition, the thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5 mm, and in this embodiment is set to 0.635 mm.

The circuit layer 12 is formed by bonding 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 a eutectic aluminum alloy to the ceramic substrate 11. A circuit pattern is formed on the circuit layer 12, and one surface (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 (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. In addition, although it is preferable that the thickness of the circuit layer 12 is 0.05 mm or more and less than 0.6 mm, it is not limited to this.
The circuit layer 12 preferably has a conductivity of 45% IACS or higher. Moreover, it is preferable that Vickers hardness is 70 Hv or less.

The metal layer 13 is formed by bonding 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 plate of an aluminum alloy 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 additive elements. It is preferable.
Moreover, it is preferable that 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 Si content 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 Cu content 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 additive element, the Ag content is preferably within the range of 3.1 mass% to 15.9 mass%.
In the case of an Al—Mg alloy containing Mg as an additive element, the Mg content is preferably in the range of 0.6 mass% to 4.5 mass%.

In the case of an Al-Si-Mg alloy containing Si and Mg as additive elements, the Si content is in the range of 0.3 mass% to 0.8 mass%, and the Mg content is 0.5 mass% to 1 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 additive elements, the Cu content is within 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 in the range of not more than 0.5 mass%.

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 the present embodiment, the heat sink 40 and the power module substrate 10 are joined by brazing using a flux whose main component is KAlF ₄ .

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

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

  In the lamination 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 aluminum is formed 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, the laminated ceramic substrate 11 and the aluminum plates 22 and 23 are loaded with a load of 0.29 MPa or more and 1.47 MPa or less in the lamination direction, and the aluminum alloy constituting the aluminum plates 22 and 23 is used. The solid-liquid coexistence region is formed at the bonding interface between the ceramic substrate 11 and the aluminum plates 22 and 23.

Here, when the load at the time of pressurizing in the laminating direction is less than 0.29 MPa, the ceramic substrate 11 and the aluminum plates 22 and 23 are not sufficiently adhered to each other, and the bonding may be insufficient. On the other hand, if the load applied in the laminating direction exceeds 1.47 MPa, the shape of the aluminum plate may not be maintained. For this reason, in this embodiment, the load at the time of pressurizing to the lamination direction is set in the range of 0.29 MPa or more and 1.47 MPa or less.
In order to make the ceramic substrate 11 and the aluminum plates 22 and 23 more closely contact each other, the lower limit of the load when pressing in the stacking direction is preferably 0.49 MPa or more, and more preferably 0.79 MPa or more. preferable. Moreover, in order to maintain the shape of an aluminum plate reliably, it is preferable to make the upper limit of the load at the time of pressurizing in a lamination direction into 1.2 MPa or less, and it is further more preferable to set it as 0.98 MPa or less.

  Further, when the holding temperature is lower than the eutectic temperature of the aluminum alloy constituting the aluminum plates 22 and 23, the liquid phase is not 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 constituting the aluminum plates 22 and 23, the aluminum plates 22 and 23 may be melted and cannot maintain their shapes. For this reason, in this embodiment, holding temperature is set in the range more than the eutectic temperature of the aluminum alloy which comprises the aluminum plates 22 and 23, and less than liquidus temperature.

  For example, when Al-1.9 mass% Si is used as the 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 within a range of 579 ° C. or more and less than 648 ° C.

  In order to securely bond the ceramic substrate 11 and the aluminum plates 22 and 23, the lower limit of the holding temperature is preferably the eutectic temperature of the aluminum alloy + 5 ° C or higher, and the eutectic temperature + 15 ° C or higher. More preferably. In order to reliably maintain the shape of the aluminum plate, the upper limit of the holding temperature is preferably set to the liquidus temperature of the aluminum alloy of −5 ° C. or lower, and the liquidus temperature of −10 ° C. or lower. Further preferred.

Next, in the solidification step S13, the ceramic substrate 11, the aluminum plate 22, and the aluminum plate 23 are solidified by solidifying the solid-liquid coexistence regions formed at the interfaces between the aluminum plates 22 and 23 and the ceramic substrate 11, respectively. Join.
Thereby, 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 joining step S02)
Next, as shown in FIG. 4, a heat sink 40 is bonded to the other surface side of the metal layer 13 of the power module substrate 10.
Specifically, between the metal layer 13 of the power module substrate 10 and the heat sink 40, an Al—Si brazing material foil 27 and a flux (not shown) containing KAlF ₄ as a main component are interposed.

Next, in a state where the laminated power module substrate 10 and the heat sink 40 are pressurized in the laminating direction (pressure 0 to 10 kgf / cm ² ), they are placed in an atmosphere heating furnace and heated, and the metal layer 13 and the heat sink are heated. 40 to form a molten metal region. And the metal layer 13 and the heat sink 40 of the board | substrate 10 for power modules are joined by solidifying the above-mentioned molten metal area | region. At this time, oxide films are formed on the surfaces of the metal layer 13 and the heat sink 40, but these oxide films are removed by the above-described 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 which is this embodiment is produced.

  According to the method for manufacturing the power module substrate 10 of the present embodiment configured as described above, in the heating step S12, the aluminum alloy constituting the circuit layer 12 and the metal layer 13 (aluminum plates 22, 23) is made. Holding at a holding temperature not lower than the eutectic temperature and lower than the liquidus temperature, forming a solid-liquid coexistence region, and bonding the ceramic substrate 11 and the aluminum plates 22 and 23, so that a large amount of liquid phase is generated at the bonding interface. There is no risk of surface abnormalities such as wax bumps and wax stains.

In addition, according to the method for manufacturing the power module substrate 10 of the present embodiment, no brazing material is used, and therefore, the bonding interface between the ceramic substrate 11, the circuit layer 12 and the metal layer 13 is different due to the brazing material. A highly anisotropic layer is not formed, and the bonding reliability is excellent.
Furthermore, even if a flux is used in the heat sink bonding step S02, there is no possibility that the bonding reliability between the ceramic substrate 11, the circuit layer 12, and the metal layer 13 is lowered due to the influence of the flux.
In addition, since a load of 0.29 MPa or more and 1.47 MPa or less is applied to the laminated ceramic substrate 11 and the aluminum plates 22 and 23 in the lamination direction at the time of joining, the ceramic substrate 11 and the aluminum plates 22 and 23 are It is possible to manufacture the power module substrate 10 that is reliably bonded and has excellent thermal cycle reliability.

  Moreover, in this embodiment, the aluminum alloy which comprises the circuit layer 12 and the metal layer 13 (aluminum plates 22 and 23) contains the 1 type (s) or 2 or more types selected from Si, Cu, Ag, and Mg as an additional element. Therefore, the eutectic temperature of the aluminum alloy is lowered, and the ceramic substrate 11 and the aluminum plates 22 and 23 can be bonded under low temperature conditions.

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

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the 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 the ceramic / aluminum bonded body is formed by bonding a ceramic member and an aluminum member made of an aluminum alloy. If it is.

In the present embodiment, the circuit layer and the metal layer have been described as formed by bonding an aluminum plate made of an aluminum alloy. However, the present invention is not limited to this, and either the circuit layer or the metal layer is used. One side should just be comprised with the aluminum plate which consists of aluminum alloys.
Specifically, if the metal layer is composed 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, You may comprise with the laminated board etc. of aluminum and copper. If the circuit layer is made of an aluminum plate made of an aluminum alloy, the metal layer is made of another metal such as an aluminum plate made of 4N aluminum having a purity of 99.99 mass% or more, or a composite material. Also good.

  In the present embodiment, the circuit layer 12 and the metal layer 13 are 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, the heat sink 40 is bonded to the surface of the power module substrate 110 opposite to the circuit layer 12.

In the present 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 ) is not limited thereto. ) And other ceramics.
Furthermore, although it demonstrated as what forms a Ni plating layer in the surface which performs a solder joint of a circuit layer and a metal layer, it is not limited to this, Even if it comprises an underlayer by other means, such as Ag paste Good.
Further, the heat sink is not limited to the one exemplified in this 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. Moreover, the heat sink which has a radiation fin may be sufficient.

  Furthermore, although it demonstrated as what forms a circuit layer by joining an aluminum plate, it is not limited to this, You may join the small piece of aluminum on the surface of the ceramic substrate in the shape of a wiring pattern. . In this case, the step of etching the circuit layer to form a wiring pattern can be omitted.

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

In the present invention example and the comparative example, aluminum plates were directly laminated on one surface and the other surface of the ceramic substrate, and these were pressed with the load shown in Table 2 in the lamination direction, and under the atmosphere shown in Table 2, and held at the holding temperature and holding time shown in Table 2, then cooled by N ₂ flow. Thereby, the board | substrate for power modules was manufactured.
For inventive examples 9 to 11, an aluminum plate was bonded to only one surface of the ceramic substrate.

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

(Initial joining rate)
The bonding rate 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 (FineSAT 200 manufactured by Hitachi Power Solutions Co., Ltd.), and calculated from the following formula. Here, the initial bonding area is the area to be bonded before bonding, that is, the area of the circuit layer (48 mm × 58 mm). In the image obtained by binarizing the ultrasonic flaw detection image, the peeling is indicated by the white portion in the joint portion. Therefore, the area of the white portion is defined as the peeling area. The evaluation results are shown in Table 2.
(Joining rate) = {(initial joining area) − (non-joining area)} / (initial joining area) × 100

(Joint rate after thermal cycle)
The joint ratio after the thermal cycle is -40 ° C x 10 minutes ← → 150 ° C x in the liquid phase (Fluorinert) with respect to the power module substrate with heat sink using TSB-51 manufactured by ESP Co., Ltd. 3000 cycles of 10 minutes were carried out, and the joining rate was evaluated by the same method as described above. The evaluation results are shown in Table 2.

(Circuit layer hardness)
In the power module substrate before the thermal cycle test described above, the surface of the circuit layer was measured with a micro Vickers hardness tester in accordance with JIS Z 2244. The evaluation results are shown in Table 2.

(Surface alteration 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. The evaluation results are shown in Table 2.
A: Surface alteration is less than 10% of the circuit layer surface area B: Surface alteration is 10% or more and less than 25% of the circuit layer surface area X: Surface alteration is 25% or more of the circuit layer surface area

In Comparative Examples 1 and 3 bonded at a temperature lower than the eutectic temperature of the aluminum alloy, a liquid phase was not formed, and bonding was not possible. In Comparative Examples 1 and 3, since the bonding could not be performed, the bonding rate 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, the circuit layer was deformed and the surface was deteriorated.
In Comparative Example 5 in which the load during bonding was less than 0.29 MPa, the bonding rate after the thermal cycle was low.
In Comparative Example 6 in which the load during bonding 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 provides a power module substrate with high bonding reliability without deformation of the circuit layer and surface alteration.

10 Power module substrate (ceramic / aluminum bonded body)
11 Ceramic substrate (ceramic member)
12 circuit layer 13 metal layer 22 aluminum plate (aluminum member)
23 Aluminum plate (aluminum member)

Claims (4)

A method for producing a ceramic / aluminum joined body in which a ceramic 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;
The laminated ceramic member and the aluminum member are loaded with a load of 0.29 MPa or more and 1.47 MPa or less in the lamination direction, and held at a holding temperature that is equal to or higher than the eutectic temperature of the aluminum alloy and lower than the liquidus temperature, A heating step of forming a solid-liquid coexistence region at the 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 comprising:   2. The method for producing a ceramic / aluminum bonded body according to claim 1, wherein the aluminum alloy contains one or more selected from Si, Cu, Ag, and Mg as additive elements.   3. The method for producing a ceramic / aluminum bonded body according to claim 1, wherein the aluminum alloy has a eutectic temperature of 530 ° C. or higher and a liquidus temperature of 640 ° C. or higher. . 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,
The said aluminum plate and the said ceramic substrate are joined by the manufacturing method of the ceramic / aluminum joined body as described in any one of Claims 1-3, The manufacturing method of the board | substrate for power modules characterized by the above-mentioned.

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