JP6432208B2 - Method for manufacturing power module substrate, and method for manufacturing power module substrate with heat sink - Google Patents

Description

The present invention, one of the power module substrate circuit layer is formed on the surface of the insulation layer, and a heat sink in the power module substrate is a method for producing a substrate for a power module with a heat sink joined.

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. In addition, as a power joule substrate, a substrate having a metal layer formed on the other surface of a ceramic substrate is also provided.

For example, in the power module shown in Patent Document 1, a power module substrate in which a circuit layer and a metal layer made of Al are formed on one surface and the other surface of a ceramic substrate, and a solder material is interposed on the circuit layer. And a semiconductor element bonded to each other.
A heat sink is bonded to the lower side of the power module substrate, and heat transmitted from the semiconductor element to the power module substrate side is dissipated to the outside through the heat sink.

By the way, when the circuit layer and the metal layer are made of Al as in the power module described in Patent Document 1, since an Al oxide film is formed on the surface, the semiconductor element and the heat sink are joined by a solder material. Can not do it.
Therefore, conventionally, as disclosed in, for example, Patent Document 2, a Ni plating film is formed on the surface of a circuit layer and a metal layer by electroless plating or the like, and then a semiconductor element and a heat sink are soldered.
Patent Document 3 discloses a technique for joining a circuit layer and a semiconductor element, and a metal layer and a heat sink by using a silver oxide paste containing silver oxide particles and a reducing agent made of an organic substance as an alternative to a solder material. Has been proposed.

However, as described in Patent Document 2, in the power module substrate in which the Ni plating film is formed on the circuit layer surface and the metal layer surface, the surface of the Ni plating film is in the process until the semiconductor element and the heat sink are joined. Deterioration due to oxidation or the like, and there is a concern that the bonding reliability between the semiconductor element and the heat sink bonded via the solder material may be reduced. Further, in the Ni plating process, masking may be performed so that Ni plating is formed in an unnecessary region and troubles such as electrolytic corrosion do not occur. As described above, when plating is performed after masking, a great amount of labor is required for the process of forming the Ni plating film on the surface of the circuit layer and the surface of the metal layer, which greatly increases the manufacturing cost of the power module. There was a problem such as.
In addition, as described in Patent Document 3, when a circuit layer and a semiconductor element, and a metal layer and a heat sink are bonded using a silver oxide paste, the bonding property between Al and the sintered body of the silver oxide paste is high. In order to be bad, it was necessary to previously form an Ag underlayer on the circuit layer surface and the metal layer surface.

Therefore, Patent Document 4 proposes a power module in which a circuit layer and a metal layer have a laminated structure of an Al layer and a Cu layer. In this case, since the Cu layer is disposed on the surface of the circuit layer and the metal layer, the semiconductor element and the heat sink can be favorably bonded using a solder material. In addition, since Cu has a larger deformation resistance than Al, when the power cycle is applied to this power module, it is possible to prevent the surface of the circuit layer and the surface of the metal layer from being greatly deformed and to generate cracks in the solder layer. It is possible to improve the bonding reliability of the semiconductor element and the circuit layer, the heat sink and the metal layer.
In the power module described in Patent Document 4, a joined body in which an Al layer and a Cu layer are joined via a Ti layer is used as a circuit layer and a metal layer. Here, a diffusion layer is formed between the Al layer and the Ti layer, and the diffusion layer is formed in order from the Al layer side by an Al-Ti layer, an Al-Ti-Si layer, and an Al-Ti-Cu layer. And a layer.

Japanese Patent No. 3171234 JP 2004-172378 A JP 2008-208442 A Japanese Patent No. 3012835

By the way, in the power module described in Patent Document 4, an Al—Ti layer or an Al—Ti— which is a hard and brittle intermetallic compound layer is formed at the bonding interface between the Al layer and the Ti layer among the circuit layer and the metal layer. Since the Cu layer is formed, there is a problem that it becomes a starting point of a crack when a heat cycle or the like is applied.
Furthermore, when a Cu plate or the like is laminated on the Al layer via a Ti foil and heated to a temperature at which the interface between the Al layer and the Ti foil is melted, a liquid phase is produced at the bonding interface, resulting in bumps, As the thickness fluctuates, there is a problem that the bonding reliability is lowered.

Here, as an alternative to the Ni plating of Patent Document 2, as described in Patent Document 4, a Ni plate is bonded to the surface of a circuit layer and a metal layer made of Al via a Ti foil to form a Ni layer. It is also possible. Furthermore, when using the silver oxide paste of patent document 3, it is also conceivable to form an Ag underlayer by bonding an Ag plate to the surface of the circuit layer and metal layer made of Al via a Ti foil.
However, when the Ni layer or the Ag layer is formed by the method described in Patent Document 4, an Al—Ti layer, an Al—Ti layer is formed at the bonding interface between the Al layer and the Ti layer, as in the case where the Cu layer is formed. There is a possibility that the bonding reliability may be lowered due to formation of a hard and brittle intermetallic compound layer such as a Ni layer or an Al-Ti-Ag layer, or formation of bumps at the bonding interface.
As described above, conventionally, an aluminum member and a metal member made of any one of copper, nickel, and silver cannot be satisfactorily bonded, and a bonded body having excellent bonding reliability cannot be obtained. .

The present invention has been made in view of the above-described circumstances, and an aluminum member and a metal member made of copper, nickel, or silver are bonded satisfactorily, and cracks in the bonded portion when a heat cycle is applied. can the generation control, a method of manufacturing a substrate for Rupa word module can joining reliability obtain substrate for good power modules, and an object of the invention to provide a method of manufacturing a power module substrate with a heat sink.

In order to solve the above-described problems, a method for manufacturing a power module substrate according to the present invention includes an insulating layer and a circuit layer formed on one surface of the insulating layer. The circuit layer comprises a joined body in which an aluminum layer, which is an aluminum member made of aluminum, and a metal member layer, which is a metal member made of copper, nickel, or silver, are joined. The Si concentration at the joint surface is in the range of 0.03 mass% or more and 1.0 mass% or less, the aluminum member is laminated on one surface of the insulating layer, and a Ti material is interposed between the aluminum member and the metal member. Interposing, laminating the aluminum member and the metal member, heating the laminated insulating layer, the aluminum member and the metal member, and And thereby joining the aluminum member, the aluminum member and the Ti material, and, by each solid phase diffusion bonding between the metal member and the Ti material, which is configured to form the circuit layer, the insulation The bonding of the layer and the aluminum member, the solid phase diffusion bonding of the aluminum member and the Ti material, and the solid phase diffusion bonding of the Ti material and the metal member are performed simultaneously .
The method for manufacturing a power module substrate of the present invention includes an insulating layer, a circuit layer formed on one surface of the insulating layer, and a metal layer formed on the other surface of the insulating layer. A method for manufacturing a power module substrate, wherein the metal layer is an aluminum layer made of aluminum and a metal member layer made of copper, nickel, or silver. The aluminum member is laminated on the other surface of the insulating layer, the Si concentration in the joining surface of the aluminum member is within the range of 0.03 mass% to 1.0 mass%, and the aluminum member and the metal Ti material is interposed between the members, the aluminum member and the metal member are laminated, and the laminated insulating layer, the aluminum member, and the metal member are laminated. Heated, said with joining the aluminum member and the insulating layer, wherein the aluminum member and the Ti material, and, by each solid phase diffusion bonding between the metal member and the Ti material, to form the metal layer structure And simultaneously performing bonding between the insulating layer and the aluminum member, solid phase diffusion bonding between the aluminum member and the Ti material, and solid phase diffusion bonding between the Ti material and the metal member. It is characterized in that.
In the present invention, the aluminum member is made of pure aluminum or an aluminum alloy, and the metal member is made of copper or a copper alloy, nickel or a nickel alloy, or silver or a silver alloy.

According to the method for manufacturing a power module substrate having this configuration, the Si concentration in the joint surface of the aluminum member is in the range of 0.03 mass% or more and 1.0 mass% or less, and between the aluminum member and the metal member. Since heating is performed with the Ti material interposed, the Ti material can suppress interdiffusion between Al in the aluminum member and Cu, Ni, or Ag in the metal member, and a hard and brittle intermetallic compound is formed. Thick formation can be prevented.
Further, when the aluminum member and the Ti material are solid-phase diffusion bonded, it is possible to suppress the Ti atoms in the Ti material from diffusing more than necessary to the aluminum member side by Si on the surface of the aluminum member, and Al and Ti It is possible to suppress the formation of a thick intermetallic compound.
Therefore, when a heat cycle is loaded, the generation of cracks at the joint can be suppressed, and a power module substrate with good joint reliability can be obtained.
In addition, when the circuit layer is a joined body in which an aluminum layer that is an aluminum member made of aluminum and a metal member layer that is a metal member made of copper, nickel, or silver are joined, the circuit layer is configured. It is possible to prevent a hard and brittle intermetallic compound from being formed thick at the joint between the aluminum layer and the metal member layer, and to suppress the occurrence of cracks at the joint when a heat cycle is applied.
Here, when an aluminum layer having a relatively small deformation resistance is formed on one surface of the insulating layer, the aluminum layer absorbs the thermal stress generated when the heat cycle is loaded, and the insulating layer is cracked. This can be suppressed.
Furthermore, when a Cu layer made of copper or a copper alloy is formed as a metal member layer to be bonded to the aluminum layer, the Cu layer has a larger deformation resistance than the aluminum layer, so that the heat cycle is loaded. In this case, the deformation of the circuit layer is suppressed, the deformation of the solder layer for bonding the semiconductor element and the circuit layer is suppressed, and the bonding reliability can be improved. In addition, since the Cu layer having a good thermal conductivity is formed on one side of the circuit layer, the heat from the semiconductor element can be spread and efficiently transmitted to the power module substrate side.
In addition, when a Ni layer made of nickel or a nickel alloy is formed as the metal member layer to be bonded to the aluminum layer, the solderability is good and the bonding reliability with the semiconductor element is improved.
When an Ag layer made of silver or a silver alloy is formed as a metal member layer bonded to the aluminum layer, for example, a semiconductor element using a silver oxide paste containing silver oxide particles and a reducing agent made of an organic substance In joining, since the silver in which silver oxide is reduced and the Ag layer are joined between the same kind of metals, the joining reliability can be improved. In addition, since the Ag layer having good thermal conductivity is formed on one side of the circuit layer, the heat from the semiconductor element can be spread and efficiently transmitted to the power module substrate side.
When the metal layer is a joined body in which an aluminum layer that is an aluminum member made of aluminum and a metal member layer that is a metal member made of copper, nickel, or silver are joined, the metal layer is configured. It is possible to prevent a hard and brittle intermetallic compound from being formed thick at the joint between the aluminum layer and the metal member layer, and to suppress the occurrence of cracks at the joint when a heat cycle is applied.
Here, when an aluminum layer having a relatively small deformation resistance is formed on the other surface of the insulating layer, the aluminum layer absorbs the thermal stress generated when the heat cycle is loaded, and the insulating layer is cracked. This can be suppressed.
Furthermore, when a Cu layer made of copper or a copper alloy is formed as a metal member layer to be bonded to the aluminum layer, the Cu layer has a larger deformation resistance than the aluminum layer, so that the heat cycle is loaded. In this case, deformation of the metal layer is suppressed, deformation of the solder layer that joins the heat sink and the metal layer can be suppressed, and bonding reliability can be improved.
In addition, when a Ni layer made of nickel or a nickel alloy is formed as the metal member layer to be bonded to the aluminum layer, the solderability is good and the bonding reliability with the heat sink is improved.
Further, when an Ag layer made of silver or a silver alloy is formed as a metal member layer bonded to the aluminum layer, for example, a heat sink is made using a silver oxide paste containing silver oxide particles and a reducing agent made of an organic substance. At the time of joining, the silver whose silver oxide has been reduced and the Ag layer are joined between the same kind of metals, so that the joining reliability can be improved.

When the Si concentration at the joint surface is less than 0.03 mass%, the effect of suppressing the diffusion of Ti is insufficient, and the intermetallic compound of Al and Ti formed at the joint is formed thick. There is a risk that. On the other hand, when the Si concentration exceeds 1.0 mass%, the melting point is lowered and a liquid phase is generated, and bumps are formed or the thickness is changed.
Therefore, in this invention, Si density | concentration in a joint surface is prescribed | regulated in the range of 0.03 mass% or more and 1.0 mass% or less.

Here, in the method for manufacturing a power module substrate according to the present invention, a Ti layer located on the metal member side at the joint between the aluminum member and the metal member by the solid phase diffusion bonding, and the Ti layer It is preferable to form an Al—Ti—Si layer in which Si is dissolved in Al ₃ Ti.
In this case, a Ti layer and an Al—Ti—Si layer are formed at the joint between the aluminum member and the metal member, and the hard and brittle Al—Ti layer or Al—Ti—Cu (Ni, Ag) layer is formed. Since the intermetallic compound layer such as is not formed, it is possible to suppress the occurrence of cracks at the joint when a heat cycle is applied, and the joining reliability between the aluminum member and the metal member can be improved.

In the method for manufacturing a power module substrate of the present invention, the Al-Ti-Si layer is formed on the first Al-Ti-Si layer formed on the Ti layer side and on the aluminum member side, It is preferable to include a second Al—Ti—Si layer having a lower Si concentration than the first Al—Ti—Si layer.
In this case, since the first Al—Ti—Si layer formed on the Ti layer side is higher than the Si concentration of the second Al—Ti—Si layer formed on the aluminum member side, the first Si concentration is high. The Al—Ti—Si layer suppresses Ti atoms from diffusing to the aluminum member side, and the thickness of the first Al—Ti—Si layer and the second Al—Ti—Si layer can be reduced. It is possible to suppress the occurrence of cracks in the joint portion when a load is applied.

The method for manufacturing a power module substrate with a heat sink according to the present invention includes an insulating layer, a circuit layer formed on one surface of the insulating layer, a metal layer formed on the other surface of the insulating layer, and the metal A power module substrate with a heat sink comprising: a heat sink bonded to a layer, wherein one of the metal layer and the heat sink is an aluminum member made of aluminum, and the metal layer and the heat sink One of the other is a metal member made of copper, nickel, or silver, and the Si concentration in the joint surface of the aluminum member is in the range of 0.03 mass% to 1.0 mass%, and the other of the insulating layers Laminating the aluminum member or the metal member to be the metal layer on a surface, and from the metal member or the aluminum member Ti material is interposed between the heat sink, the aluminum member and the metal member are laminated, the laminated aluminum member and the metal member are heated, and the insulating layer and the metal layer are formed. A structure in which the metal layer and the heat sink are bonded together by bonding the aluminum member or the metal member, and solid-phase diffusion bonding the aluminum member and the Ti material, and the Ti material and the metal member, respectively. The aluminum member or the metal member to be the insulating layer and the metal layer, the solid phase diffusion bonding between the aluminum member and the Ti material, and the solid material between the Ti material and the metal member. The phase diffusion bonding is performed at the same time .

According to the method for manufacturing a power module substrate with a heat sink having this configuration, the Si concentration in the joint surface of the aluminum member is in the range of 0.03 mass% to 1.0 mass%, and the aluminum member and the metal member Since heating is performed with a Ti material interposed therebetween, the Ti material can suppress interdiffusion between Al in the aluminum member and Cu, Ni or Ag in the metal member, and between hard and brittle metals It is possible to prevent the compound from being formed thick.
Further, when the aluminum member and the Ti material are solid-phase diffusion bonded, it is possible to suppress the Ti atoms in the Ti material from diffusing more than necessary to the aluminum member side by Si on the surface of the aluminum member, and Al and Ti It is possible to suppress the formation of a thick intermetallic compound.
Therefore, when a heat cycle is loaded, the generation of cracks at the joint can be suppressed, and a power module substrate with a heat sink with good joining reliability can be obtained.
Here, in the method for manufacturing a power module substrate with a heat sink according to the present invention, the Ti layer located on the metal member side at the joint between the aluminum member and the metal member by the solid phase diffusion bonding, It is preferable to form an Al—Ti—Si layer that is located between the Ti layer and the aluminum member and in which Si is dissolved in Al ₃ Ti.
In the method for manufacturing a power module substrate with a heat sink according to the present invention, the Al-Ti-Si layer is formed on the first Al-Ti-Si layer formed on the Ti layer side and on the aluminum member side. And a second Al—Ti—Si layer having a lower Si concentration than the first Al—Ti—Si layer.

According to the present invention, an aluminum member and a metal member made of copper, nickel, or silver are bonded satisfactorily, and when a heat cycle is loaded, generation of cracks at the bonded portion can be suppressed, and bonding reliability is good. method of manufacturing a substrate for Rupa word module can get Do conjugate, and it is possible to provide a method of manufacturing a power module substrate with a heat sink.

It is a schematic explanatory drawing of the power module provided with the board | substrate for power modules which concerns on 1st embodiment of this invention. FIG. 2 is an enlarged explanatory diagram of a bonding interface between an Al layer and a Ti layer of a circuit layer in FIG. 1. It is a flowchart explaining the manufacturing method of the board | substrate for power modules which concerns on 1st embodiment. In 1st embodiment, it is a schematic explanatory drawing of the process of adjusting Si density | concentration in the joint surface of the aluminum plate used as Al layer. It is a schematic explanatory drawing of the manufacturing method of the board | substrate for power modules which concerns on 1st embodiment. It is a schematic explanatory drawing of the power module provided with the board | substrate for power modules which concerns on 2nd embodiment of this invention. FIG. 7 is an enlarged explanatory view of a bonding interface between an Al layer and a Ti layer of the metal layer in FIG. 6. It is a flowchart explaining the manufacturing method of the board | substrate for power modules which concerns on 2nd embodiment. It is a schematic explanatory drawing of the manufacturing method of the board | substrate for power modules which concerns on 2nd embodiment. It is a schematic explanatory drawing of the power module provided with the board | substrate for power modules with a heat sink which concerns on 3rd embodiment of this invention. FIG. 11 is an enlarged explanatory view of a bonding interface between a metal layer and a Ti layer in FIG. 10. It is a flowchart explaining the manufacturing method of the board | substrate for power modules with a heat sink which concerns on 3rd embodiment. It is a schematic explanatory drawing of the manufacturing method of the board | substrate for power modules with a heat sink which concerns on 3rd embodiment.

(First embodiment)
Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, the power module 1 using the board | substrate 10 for power modules which is 1st embodiment of this invention is shown.
The power module 1 includes a power module substrate 10 and a semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the power module substrate 10 via a solder layer 2.

  The power module substrate 10 according to the present embodiment includes a ceramic substrate 11 constituting an insulating layer, a circuit layer 12 disposed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11, and the ceramic substrate 11. And a metal layer 13 disposed on the other surface (the lower surface in FIG. 1).

The ceramic substrate 11 is made of highly insulating AlN (aluminum nitride), Si ₃ N ₄ (silicon nitride), Al ₂ O ₃ (alumina), or the like. In this embodiment, it is comprised with AlN (aluminum nitride) excellent in heat dissipation. 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.

  As shown in FIG. 1, the circuit layer 12 includes an Al layer 12A disposed on one surface of the ceramic substrate 11, and a Cu layer 12B laminated on one surface of the Al layer 12A via a Ti layer 15. (Metal member layer). That is, in the present embodiment, the circuit layer 12 is a joined body in which an aluminum member (Al layer) and a metal member (Cu layer) are joined.

As shown in FIG. 5, the Al layer 12 </ b> A is formed by joining an aluminum plate 22 </ b> A (aluminum member) made of aluminum or an aluminum alloy to one surface of the ceramic substrate 11. The thickness of the aluminum plate 22A to be joined is set within a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.4 mm in the present embodiment.
The Cu layer 12B is formed by joining a copper plate 22B (metal member) made of copper or a copper alloy to one surface (the upper surface in FIG. 1) of the Al layer 12A via the Ti layer 15. In the present embodiment, the Cu layer 12B is formed by solid-phase diffusion bonding a rolled plate of oxygen-free copper to the Al layer 12A (aluminum plate 22B) via the titanium foil 25. In addition, the thickness of the copper plate 22B to be joined is set within a range of 0.1 mm or more and 6.0 mm or less, and is set to 1.0 mm in the present embodiment.

The Ti layer 15 is formed by laminating an Al layer 12A and a copper plate 22B via a titanium foil 25 and performing solid phase diffusion bonding. Here, the purity of the titanium foil 25 is 99 mass% or more. Further, the thickness of the titanium foil 25 is set to 3 μm or more and 40 μm or less, and in this embodiment, it is set to 10 μm.
As shown in FIG. 2, an Al—Ti—Si layer 16 in which Si is dissolved in Al ₃ Ti is formed at the bonding interface between the Al layer 12 </ b> A and the Ti layer 15.

The Al—Ti—Si layer 16 is formed by interdiffusion of Al atoms in the Al layer 12A and Ti atoms in the Ti layer 15. The thickness of the Al—Ti—Si layer 16 is set to 0.5 μm or more and 10 μm or less, and is 3 μm in the present embodiment.
As shown in FIG. 2, the Al—Ti—Si layer 16 includes a first Al—Ti—Si layer 16A formed on the Ti layer 15 side and a second Al—Ti— layer formed on the Al layer 12A side. Si layer 16B. That is, the Ti layer 15, the first Al—Ti—Si layer 16A, and the second Al—Ti—Si layer 16B are formed at the joint between the Al layer 12A and the Cu layer 12B.

The first Al—Ti—Si layer 16A and the second Al—Ti—Si layer 16B are made of an Al—Ti—Si phase in which Si is dissolved in Al ₃ Ti, and the second Al—Ti—Si layer 16B. The Si concentration of the first Al—Ti—Si layer 16A is lower than the Si concentration. In the present embodiment, Si contained in the first Al—Ti—Si layer 16A and the second Al—Ti—Si layer 16B is composed of Si present on the bonding surface of the aluminum plate 22A. It is diffused and concentrated.
The Si concentration of the first Al—Ti—Si layer 16A is 10 at% or more and 30 at% or less, and is 20 at% in this embodiment. The Si concentration of the second Al—Ti—Si layer 16B is 1 at% or more and 10 at% or less, and is 3 at% in this embodiment.

  The metal layer 13 is formed by joining an aluminum plate made of aluminum or an aluminum alloy to the other surface (the lower surface in FIG. 1) of the ceramic substrate 11. In the present embodiment, the metal layer 13 is formed by joining an aluminum (4N aluminum) rolled plate having a purity of 99.99 mass% or more to the ceramic substrate 11. In addition, the thickness of the aluminum plate used as the metal layer 13 is set in the range of 0.1 mm or more and 3.0 mm or less, and is set to 1.6 mm in this embodiment.

The semiconductor element 3 is made of a semiconductor material such as Si. The semiconductor element 3 and the circuit layer 12 are joined via the solder layer 2.
The solder layer 2 is, for example, a Sn-Ag, Sn-Cu, Sn-In, or Sn-Ag-Cu solder material (so-called lead-free solder material). The element 3 is joined.

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

(Aluminum plate Si concentration adjusting step S01)
First, an aluminum plate 22A to be the Al layer 12A is prepared. In this embodiment, as shown in FIG. 4, two rolled plates 22Aa and 22Ab made of 4N aluminum having a purity of 99.99 mass% or more are prepared, and these two rolled plates 22Aa and 22Ab are passed through the Si material 27. Laminate and heat under pressure. Then, Si diffuses from the Si material 27 to the rolled plates 22Aa and 22Ab made of 4N aluminum. Thereafter, the two rolled plates 22Aa and 22Ab are separated to obtain two aluminum plates 22A and 22A. In this aluminum plate 22A, the Si concentration on the surface in contact with the Si material 27 is in the range of 0.03 mass% or more and 1.0 mass% or less.

Here, the pressure load is in the range of 0.3 MPa to 1.5 MPa, the heating temperature is in the range of 450 ° C. to less than 576 ° C., and the holding time is in the range of 5 min to 150 min. Si is solid-phase diffused without causing the above.
Further, as the Si material, an Al—Si alloy foil may be used, or Si may be fixed by vapor deposition or the like. In this embodiment, an Al-10 mass% Si alloy foil having a thickness of 20 μm is interposed.
It should be noted that by adjusting the heating temperature, holding time, and the amount of Si in the Si material 27, the Si concentration at the bonding surface of the aluminum plate 22A can be controlled.
Here, since the pressurization load is set to 0.3 MPa or more, the Si material and the rolled plate are in close contact with each other, and Si is diffused uniformly and sufficiently. Moreover, since the load is 1.5 MPa or less, the two rolled sheets can be reliably separated without being joined.
Furthermore, since the heating temperature is set to 450 ° C. or higher, productivity can be improved without slowing the diffusion rate of Si. Moreover, since the heating temperature is less than 576 ° C., the rolled plate does not melt.
In addition, since the holding time is set to 5 min or more, Si can be sufficiently diffused, and an intermetallic compound of Al and Ti formed at the junction in the circuit layer and metal layer forming step S03 described later. It can be formed thin. Further, since the holding time is set to 150 min or less, Si is not excessively diffused, and the rolled sheet does not melt.

(Aluminum plate and copper plate lamination step S02)
Next, as shown in FIG. 5, an aluminum plate 22A to be an Al layer 12A is laminated on one surface of the ceramic substrate 11, and a copper plate 22B to be a Cu layer 12B is further laminated thereon via a titanium foil 25. To do. At this time, the surface of the aluminum plate 22A in which the Si concentration was in the range of 0.03 mass% or more and 1.0 mass% or less was defined as a bonding surface with the copper plate 22B.
On the other hand, an aluminum plate 23 to be the metal layer 13 is laminated on the other surface of the ceramic substrate 11. Here, in this embodiment, the aluminum plates 22 </ b> A and 23 and the ceramic substrate 11 are laminated via an Al—Si brazing material foil 26.

(Circuit layer and metal layer forming step S03)
Next, the aluminum plate 22A and the ceramic substrate 11 and the ceramic substrate 11 and the aluminum plate 23 are joined by placing and heating in a vacuum heating furnace under pressure (pressure 1 to 35 kgf / cm ² ) in the stacking direction, The aluminum plate 22A and the titanium foil 25, and the copper plate 22B and the titanium foil 25 are solid-phase diffusion bonded to form the circuit layer 12 and the metal layer 13.

Here, the pressure in the vacuum heating furnace is set in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is set to 600 ° C. to 643 ° C., and the holding time is set in the range of 30 minutes to 180 minutes. It is preferable. A more preferable heating temperature is in the range of 630 ° C. or more and 643 ° C. or less. In this embodiment, a pressure of 12 kgf / cm ² was applied in the stacking direction, and the heating temperature was 640 ° C. and the holding time was 60 minutes.
Each surface to which the aluminum plate 22A, the titanium foil 25, and the copper plate 22B are bonded is solid-phase diffusion bonded after the scratches on the surfaces have been removed and smoothed in advance.
As described above, the power module substrate 10 according to the present embodiment is manufactured.

(Semiconductor element bonding step S04)
Next, the semiconductor element 3 is laminated on one surface (front surface) of the circuit layer 12 via a solder material, and soldered in a reduction furnace.
As described above, the power module 1 according to the present embodiment is manufactured.

According to the method for manufacturing the power module substrate 10 according to the present embodiment configured as described above, the circuit layer 12 is configured by the joined body of the Al layer 12A and the Cu layer 12B, and becomes the Al layer 12A. The Si concentration in the joint surface of the aluminum plate 22A with the copper plate 22B is in the range of 0.03 mass% or more and 1.0 mass% or less, and the aluminum plate 22A and the copper plate 22B are laminated with the titanium foil 25 interposed therebetween. Since 22A and titanium foil 25 and copper plate 22B and titanium foil 25 are solid phase diffusion bonded, the titanium foil 25 can suppress the mutual diffusion of Al in the aluminum plate 22A and Cu in the copper plate 22B. And thick brittle intermetallic compounds can be prevented.
Further, when the aluminum plate 22A and the titanium foil 25 are solid-phase diffusion bonded, Ti atoms in the titanium foil 25 are diffused more than necessary to the aluminum plate 22A side by Si present on the bonding surface of the aluminum plate 22A. Therefore, it is possible to reduce the thickness of the intermetallic compound layer of Al and Ti formed at the joint.

  Further, in the present embodiment, in the aluminum plate Si concentration adjusting step S01, two rolled plates 22Aa and 22Ab made of 4N aluminum having a purity of 99.99 mass% or more are prepared, and the two rolled plates 22Aa and 22Ab are prepared as Si. Since the Si is diffused from the Si material 27 toward the rolled plates 22Aa and 22Ab made of 4N aluminum, the Si concentration on the joining surface is 0.03 mass% or more. An aluminum plate 22A that is 1.0 mass% or less can be obtained. In this aluminum plate 22A, the amount of impurities other than Si is small (for example, the Fe content is 20 mass ppm or less), Si is concentrated on the joint surface, and the deformation resistance of the formed Al layer 12A is reduced. It is possible to absorb the thermal stress sufficiently.

  In the present embodiment, in the circuit layer 12, the Ti layer 15 and the Al—Ti—Si layer 16 are formed at the joint between the Al layer 12A and the Cu layer 12B, and the hard and brittle Al—Ti layer is formed. Since no layer or Al—Ti—Cu layer is formed, it is possible to suppress the occurrence of cracks in the joint when a heat cycle is applied, and to improve the joining reliability between the Al layer 12A and the Cu layer 12B. it can.

  In the present embodiment, the Si concentration of the first Al—Ti—Si layer 16A formed on the Ti layer 15 side is greater than the Si concentration of the second Al—Ti—Si layer 16B formed on the Al layer 12A side. Therefore, the first Al—Ti—Si layer 16A having a high Si concentration prevents Ti atoms from diffusing toward the Al layer 12A, and the thickness of the Al—Ti—Si layer 16 can be reduced. And by reducing the thickness of the Al—Ti—Si layer 16 in this way, it is possible to suppress the occurrence of cracks at the joint between the Al layer 12A and the Cu layer 12B when a heat cycle is loaded. Become.

Further, since the Si concentration contained in the second Al—Ti—Si layer 16B formed on the Al layer 12A side is 1 at% or more and 10 at% or less, Al atoms diffuse excessively on the Ti layer 15 side. Is suppressed, and the thickness of the second Al—Ti—Si layer 16B can be reduced.
Furthermore, since the Si concentration contained in the first Al—Ti—Si layer 16A formed on the Ti layer 15 side is 10 at% or more and 30 at% or less, Ti atoms are excessively diffused on the Al layer 12A side. Therefore, the thickness of the first Al—Ti—Si layer 16A can be reduced.

  Moreover, in this embodiment, since it is set as the structure which joins the aluminum plate 22A, the titanium foil 25, the copper plate 22B, and the aluminum plate 23 to the one surface and the other surface of the ceramic substrate 11 at a time, a manufacturing process The manufacturing cost can be reduced.

Further, since the Al layer 12A having a relatively small deformation resistance is formed on one surface of the ceramic substrate 11, the Al layer 12A absorbs the thermal stress generated when the heat cycle is loaded, and the ceramic substrate 11 is cracked. Can be prevented from occurring.
Furthermore, since the Cu layer 12B having a relatively large deformation resistance is formed on one surface of the Al layer 12A, the deformation of the circuit layer 12 is suppressed when a heat cycle is applied, and the semiconductor element 3 and the circuit The deformation of the solder layer 2 that joins the layer 12 can be suppressed, and the joining reliability can be improved.
In addition, since the Cu layer 12B having good thermal conductivity is formed on one side of the circuit layer 12, heat from the semiconductor element 3 can be spread and efficiently transmitted to the power module substrate 10 side.

In the present embodiment, the solid phase diffusion bonding of the Al layer 12A (aluminum plate 22A) and the titanium foil 25, and the copper plate 22B and the titanium foil 25 is applied with a pressure of 1 to 35 kgf / cm ^{2 in} the stacking direction. In this state, the temperature is maintained at 600 ° C. or higher and 643 ° C. or lower, so that Ti atoms can be introduced into the Al layer 12A and the copper plate 22B without generating a liquid phase at the interface between the Al layer and the Ti layer. The Al layer 12A, the titanium foil 25, and the copper plate 22B can be reliably bonded by diffusing and solid-phase diffusion bonding of Al atoms and Cu atoms in the titanium foil 25.

  When the temperature at the time of solid phase diffusion bonding is 600 ° C. or higher, the diffusion of Al atoms, Ti atoms, and Cu atoms is promoted, and solid phase diffusion can be sufficiently achieved in a short time. Moreover, in the case of 643 degrees C or less, it can suppress that the liquid phase by melting | fusing of aluminum arises, a bump is produced in a joining interface, or thickness changes. Therefore, the preferable temperature range of solid phase diffusion bonding is set to the above range.

  Further, when there are scratches on the surfaces to be joined when solid phase diffusion bonding is performed, gaps may be generated during solid phase diffusion bonding. In this embodiment, the aluminum plate 22A, the copper plate 22B, and the titanium foil 25 Since the surfaces to be joined are solid phase diffusion bonded after the scratches on the surfaces have been removed and smoothed in advance, it is possible to reliably join by suppressing the formation of gaps at the respective joining interfaces. It is.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In addition, about the thing of the same structure as 1st embodiment, the same code | symbol is attached | subjected and described, and detailed description is abbreviate | omitted.
FIG. 6 shows a power module 101 including a power module substrate 130 with a heat sink according to a second embodiment of the present invention.
The power module 101 includes a power module substrate 130 with a heat sink and a semiconductor element 3 bonded to one surface (the upper surface in FIG. 6) of the power module substrate 130 with a heat sink via a solder layer 2. ing.
The power module substrate 130 with a heat sink includes a power module substrate 110 and a heat sink 131 bonded to the lower side of the power module substrate 110 via a solder layer 135.

The heat sink 131 is for dissipating heat on the power module substrate 110 side. The heat sink 131 is made of copper or a copper alloy, and is made of oxygen-free copper in this embodiment.
The solder layer 135 is, for example, a Sn—Ag, Sn—Cu, Sn—In, or Sn—Ag—Cu solder material (so-called lead-free solder material).

  The power module substrate 110 is disposed on the ceramic substrate 11 constituting the insulating layer, the circuit layer 112 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 6), and the other surface of the ceramic substrate 11. And a metal layer 113 (joined body) provided.

  As shown in FIG. 9, the circuit layer 112 is formed by joining an aluminum plate 122 made of aluminum or an aluminum alloy to one surface of the ceramic substrate 11. In the present embodiment, the circuit layer 112 is formed by joining a rolled plate of aluminum (2N aluminum) having a purity of 99 mass% or more to the ceramic substrate 11. In addition, the thickness of the aluminum plate 122 used as the circuit layer 112 is set within a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.6 mm in the present embodiment.

  As shown in FIG. 1, the metal layer 113 includes an Al layer 113A (aluminum member) disposed on the other surface of the ceramic substrate 11 and the opposite side of the surface of the Al layer 113A to which the ceramic substrate 11 is bonded. And a Cu layer 113B (metal member layer) laminated on the surface via the Ti layer 115.

As shown in FIG. 9, the Al layer 113 </ _b > A is formed by joining aluminum plates 123 </ _b > A ₁ and 123 </ _b > A ₂ (aluminum member) made of aluminum or an aluminum alloy to the other surface of the ceramic substrate 11. The total thickness of the aluminum plates 123A ₁ and 123A ₂ to be joined is set within a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.4 mm in this embodiment.
The Cu layer 113B is formed by bonding a copper plate 123B (metal member) made of copper or a copper alloy to the other surface of the Al layer 113A via the Ti layer 115.

As shown in FIG. 7, an Al—Ti—Si layer 116 in which Si is dissolved in Al ₃ Ti is formed at the bonding interface between the Al layer 113A and the Ti layer 115.
The Al—Ti—Si layer 116 has the same configuration as the Al—Ti—Si layer 16 in the first embodiment, and includes a first Al—Ti—Si layer 116A formed on the Ti layer 115 side, and an Al layer. And a second Al—Ti—Si layer 116B formed on the 113A side.

  Next, a method for manufacturing the power module substrate 130 with a heat sink according to the present embodiment will be described with reference to FIGS.

(Aluminum plate lamination step S101)
First, as shown in FIG. 9, an aluminum plate 122 to be the circuit layer 112 was laminated on one surface of the ceramic substrate 11 with an Al—Si brazing material foil 26 interposed therebetween.
Also, two aluminum plates 123A ₁ and 123A ₂ to be the Al layer 113A are laminated on the other surface of the ceramic substrate 11. At this time, it was interposed brazing material foil 26 of Al-Si system between the ceramic substrate 11 and the aluminum plate 123A _1. Between the aluminum plate 123A ₁ and the aluminum plate 123A ₂ is interposed a Si material 127. As the Si material 127, a plate or foil of Si alloy such as Si or Al—Si alloy can be used. Furthermore, Si or Si alloy powder may be used as the Si material 127. Alternatively, the Si material 127 may be formed by evaporating Si on an aluminum plate. As the Si material 127, an Al—Si alloy foil having a thickness of 1 μm to 20 μm and an Si concentration of 1 mass% to 12 mass% is preferably used.
In this embodiment, an Al-7 mass% Si alloy foil having a thickness of 10 μm is interposed as the Si material 127. Further, as the two aluminum plates 123A ₁ and 123A ₂ , 4N aluminum rolled plates having a purity of 99.99 mass% or more were used.

(Circuit layer and Al layer forming step S102)
And it arrange | positions and heats in a vacuum heating furnace in the state (pressure 1-35kgf / cm < ² >) pressurized in the lamination direction, the aluminum plate 122 and the ceramic substrate 11 are joined, and the circuit layer 112 is formed. Further, the ceramic substrate 11 and the aluminum plate 123A ₁ , and the aluminum plate 123A ₁ and the aluminum plate 123A ₂ are joined to form an Al layer 113A.
At this time, by the Si in the Si material 127 is diffused into the aluminum plate 123A in _2, below 1.0 mass% Si concentration is more than 0.03 mass% in the (junction surface between the copper plate 123B) the other surface of the Al layer 113A Within the range of
Here, the pressure in the vacuum heating furnace is set in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is set to 600 ° C. to 640 ° C., and the holding time is set in the range of 5 minutes to 180 minutes. It is preferable.

(Cu layer forming step S103)
Next, a copper plate 123B to be the Cu layer 113B is laminated on the other surface side of the Al layer 113A with the titanium foil 125 interposed therebetween.
And it arrange | positions and heats in a vacuum heating furnace in the state (pressure 1-35kgf / cm < ² >) in the lamination direction, and solid-phase diffusion of Al layer 113A, titanium foil 125, titanium foil 125, and copper plate 123B Bonding is performed to form a metal layer 113 made of a bonded body.
Here, the pressure in the vacuum heating furnace is set in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is set to 600 ° C. to 640 ° C., and the holding time is set in the range of 30 minutes to 180 minutes. It is preferable.
The respective surfaces to which the Al layer 113A, the titanium foil 125, and the copper plate 123B are bonded are solid-phase diffusion bonded after the scratches on the surfaces have been removed and smoothed in advance.
As described above, the power module substrate 110 according to the present embodiment is manufactured.

(Heat sink joining step S104)
Next, a heat sink 131 is stacked on the metal layer 113 of the power module substrate 110 via a solder material, and soldered in a reduction furnace.
In this manner, the power module substrate with heat sink 130 according to the present embodiment is manufactured.

(Semiconductor element bonding step S105)
Next, the semiconductor element 3 is laminated on one surface (front surface) of the circuit layer 112 via a solder material, and soldered in a reduction furnace.
As described above, the power module 101 according to the present embodiment is manufactured.

According to the method for manufacturing the power module substrate 110 according to the present embodiment configured as described above, the metal layer 113 is configured by the joined body of the Al layer 113A and the Cu layer 113B, and the copper plate of the Al layer 113A. The Si concentration at the joint surface with 123B is in the range of 0.03 mass% or more and 1.0 mass% or less, and the Al layer 113A and the copper plate 123B are laminated via the titanium foil 125, and the Al layer 113A, the titanium foil 125, and titanium are laminated. Since the foil 125 and the copper plate 123B are solid-phase diffusion bonded, the titanium foil 125 can suppress the mutual diffusion of Al in the Al layer 113A and Cu in the copper plate 123B, and a hard and brittle intermetallic compound is formed. Thick formation can be prevented.
Further, when the Al layer 113A and the titanium foil 125 are bonded by solid phase diffusion, Ti atoms in the titanium foil 125 are diffused more than necessary to the Al layer 113A side by Si present on the bonding surface of the Al layer 113A. Therefore, it is possible to reduce the thickness of the intermetallic compound layer of Al and Ti formed at the bonding interface.

Further, in the present embodiment, two aluminum plates 123A ₁ and 123A ₂ made of 4N aluminum rolled plates having a purity of 99.99 mass% or more are stacked via the Si material 127, and the Si material 127 to the aluminum plate 123A ₂ are stacked. Since Si is diffused into the Al layer 113A, it is possible to form the Al layer 113A in which the Si concentration at the joint surface with the copper plate 123B is 0.03 mass% or more and 1.0 mass% or less. In the Al layer 113A, the amount of impurities other than Si is small (for example, the Fe content is 20 mass ppm or less), and the deformation resistance of the Al layer 113A is kept low.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In addition, about the thing of the same structure as 1st embodiment, the same code | symbol is attached | subjected and described, and detailed description is abbreviate | omitted.
In FIG. 10, the power module 201 provided with the board | substrate 230 for power modules with a heat sink which concerns on 3rd embodiment of this invention is shown.
The power module 201 includes a power module substrate 230 with a heat sink, and a semiconductor element 3 bonded to one surface (the upper surface in FIG. 10) of the power module substrate 230 with a heat sink via a solder layer 2. ing.

  The power module substrate 230 with a heat sink includes a power module substrate 210 and a heat sink 231 (metal member) laminated on the lower side of the power module substrate 210 via a Ti layer 215.

  As shown in FIG. 10, the power module substrate 210 includes a ceramic substrate 11, a circuit layer 212 disposed on one surface (the upper surface in FIG. 10) of the ceramic substrate 11, and the other surface of the ceramic substrate 11. And a metal layer 213 disposed on the lower surface in FIG.

  As shown in FIG. 13, the circuit layer 212 is formed by bonding a conductive aluminum plate 222 to one surface of the ceramic substrate 11. In the present embodiment, the circuit layer 212 is formed by joining rolled sheets of aluminum (4N aluminum) having a purity of 99.99 mass% or more. In addition, the thickness of the aluminum plate 222 to be joined is set within a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.6 mm in the present embodiment.

  As shown in FIG. 13, the metal layer 213 is formed by joining an aluminum plate 223 made of aluminum or an aluminum alloy to the other surface of the ceramic substrate 11. In the present embodiment, the metal layer 213 is formed by joining a rolled sheet of an aluminum alloy in which Si is added to aluminum having a purity of 99.99 mass% or more (4N aluminum) in a range of 0.03 mass% to 1.0 mass%. Is formed. In addition, the thickness of the aluminum plate 223 to be joined is set within a range of 0.1 mm or more and 3.0 mm or less, and is set to 0.6 mm in the present embodiment.

The heat sink 231 is for dissipating heat on the power module substrate 210 side. The heat sink 231 is made of copper or a copper alloy, and is made of oxygen-free copper in this embodiment. The heat sink 231 is provided with a flow path 232 for flowing a cooling fluid.
The metal layer 213 (aluminum member) and the heat sink 231 (metal member) are joined via the Ti layer 215.

The Ti layer 215 is formed by laminating a metal layer 213 made of aluminum and a heat sink 231 made of copper via a titanium foil 225 and solid phase diffusion bonding.
As shown in FIG. 11, an Al—Ti—Si layer 216 in which Si is dissolved in Al ₃ Ti is formed at the bonding interface between the metal layer 213 and the Ti layer 215.
The Al—Ti—Si layer 216 has the same configuration as the Al—Ti—Si layer 16 in the first embodiment, and includes a first Al—Ti—Si layer 216A formed on the Ti layer 215 side, and a metal layer. And a second Al—Ti—Si layer 216B formed on the 213 side.

  Next, a method for manufacturing the power module substrate 230 with heat sink according to the present embodiment will be described with reference to FIGS.

(Aluminum plate and heat sink lamination step S201)
First, as shown in FIG. 13, an aluminum plate 222 to be a circuit layer 212 is laminated on one surface of the ceramic substrate 11 with an Al—Si brazing material foil 26 interposed therebetween. In addition, an aluminum plate 223 to be the metal layer 213 is laminated on the other surface of the ceramic substrate 11 with the brazing material foil 26 interposed therebetween.
Then, a heat sink 231 is laminated on the other surface side of the aluminum plate 223 with a titanium foil 225 interposed therebetween.

(Aluminum plate and heat sink joining step S202)
Next, the aluminum plates 222 and 223, the ceramic substrate 11, and the heat sink 231 are pressed in the stacking direction (pressure 1 to 35 kgf / cm ² ), placed in a vacuum heating furnace and heated, and one of the ceramic substrates 11 is heated. The circuit layer 212 and the metal layer 213 are formed on one surface and the other surface, the metal layer 213 and the titanium foil 225, and the heat sink 231 and the titanium foil 225 are solid-phase diffusion bonded, and the metal layer 213 and the heat sink 231 are bonded. To do.

(Semiconductor element bonding step S203)
Next, the semiconductor element 3 is laminated on one surface of the power module substrate 230 (circuit layer 212) with a heat sink via a solder material, and soldered in a reduction furnace.
As described above, the power module 201 according to the present embodiment is manufactured.

According to the method for manufacturing the power module substrate with heat sink 230 according to the present embodiment configured as described above, the Si concentration in the joint surface of the metal layer 213 with the heat sink 231 is 0.03 mass% or more and 1.0 mass. %, The metal layer 213 and the heat sink 231 are laminated via the titanium foil 225, and the metal layer 213, the titanium foil 225, and the titanium foil 225 and the heat sink 231 are bonded by solid phase diffusion. The foil 225 can suppress the mutual diffusion of Al in the metal layer 213 and Cu in the heat sink 231, and can prevent a hard and brittle intermetallic compound from being formed thick.
Further, when the metal layer 213 and the titanium foil 225 are solid-phase diffusion bonded, the Ti atoms in the titanium foil 225 are diffused more than necessary to the metal layer 213 side due to Si present on the bonding surface of the metal layer 213. Therefore, it is possible to reduce the thickness of the intermetallic compound layer of Al and Ti formed at the bonding interface.

  Furthermore, in this embodiment, since the metal layer 213 is formed using the aluminum plate 223 obtained by adding Si to 4N aluminum having a purity of 99.99 mass% or higher, the Si concentration at the joint surface with the heat sink is 0.03 mass%. The metal layer 213 with 1.0 mass% or less can be formed. In this metal layer 213, the amount of impurities other than Si is small (for example, the Fe content is 20 mass ppm or less), and the deformation resistance is kept low.

  In the present embodiment, the circuit layer 212 and the metal layer 213 can be formed on one surface and the other surface of the ceramic substrate 11, and the metal layer 213 and the heat sink 231 can be bonded at the same time. The process can be simplified and the manufacturing cost can be reduced.

  In this embodiment, the metal layer is made of aluminum and the heat sink is made of copper. However, the metal layer can be made of copper and the heat sink can be made of aluminum. In this case, the heat sink is made of an aluminum alloy having a Si concentration of 0.03 mass% or more and 1.0 mass% or less, or Si is added to 4N aluminum having a purity of 99.99 mass% or more, so that the bonding surface with the metal layer Aluminum whose Si concentration is 0.03 mass% or more and 1.0 mass% or less can be used.

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 above embodiment, the case where the Al layer and the Cu layer made of copper as the metal member layer are joined has been described. However, instead of the Cu layer, a Ni layer made of nickel or a nickel alloy, or silver or An Ag layer made of a silver alloy may be bonded.

  When the Ni layer is formed instead of the Cu layer, the solderability becomes good and the bonding reliability with the semiconductor element and the heat sink can be improved. Further, when the Ni layer is formed by solid phase diffusion bonding, the masking process performed when forming the Ni plating film by electroless plating or the like is not necessary, so that the manufacturing cost can be reduced. In this case, the thickness of the Ni layer is preferably 1 μm or more and 30 μm or less. If the thickness of the Ni layer is less than 1 μm, the effect of improving the reliability of bonding with the semiconductor element or the heat sink may be lost. If the thickness exceeds 30 μm, the Ni layer becomes a thermal resistor and efficiently transfers heat. There is a risk that it will not be possible. When the Ni layer is formed by solid phase diffusion bonding, the solid phase diffusion bonding can be formed under the same conditions as in the above-described embodiment.

  When an Ag layer is formed instead of the Cu layer, for example, when a semiconductor element or a heat sink is bonded using a silver oxide paste containing silver oxide particles and a reducing agent made of an organic material, the silver oxide is reduced. Since the Ag layer and the Ag layer are bonded to each other, the bonding reliability can be improved. Furthermore, since an Ag layer having a good thermal conductivity is formed, heat can be spread efficiently by spreading in the surface direction. In this case, the thickness of the Ag layer is preferably 1 μm or more and 20 μm or less. When the thickness of the Ag layer is less than 1 μm, there is a risk that the effect of improving the bonding reliability with the semiconductor element or the heat sink may be lost, and when it exceeds 20 μm, the effect of improving the bonding reliability is not observed, and the cost Incurs an increase. Further, when forming the Ag layer by solid phase diffusion bonding, the solid phase diffusion bonding can be formed under the same conditions as in the above-described embodiment.

Furthermore, in the above-described embodiment, an aluminum plate to be an Al layer is laminated on one surface of the ceramic substrate 11 via an Al—Si brazing material foil, and a Cu layer is further formed thereon via a titanium foil. Although the joined body was formed by laminating and heating by pressing the copper plate, a clad material made of Ti / Cu can be used instead of the titanium foil and the copper plate. Further, a clad material composed of three layers of Al—Si / Ti / Cu can be used instead of the aluminum plate, the titanium foil, and the copper plate.
Moreover, when forming a Ni layer instead of a Cu layer, a clad material made of Ti / Ni or a clad material made of Al—Si / Ti / Ni can be used.
Furthermore, when an Ag layer is formed instead of the Cu layer, a clad material made of Ti / Ag or a clad material made of Al—Si / Ti / Ag can be used.

Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.
The power modules of Invention Examples 1 to 6 and Comparative Examples 1 and 2 were produced as follows.
An aluminum plate (thickness 0.6 mm) to be an Al layer is laminated on one surface of the ceramic substrate described in Table 1, and further a metal plate (metal member) described in Table 1 is laminated on the titanium plate via a titanium foil. To do. Further, a 4N aluminum plate (thickness 0.6 mm) having a purity of 99.99 mass% or more, which becomes a metal layer, is laminated on the other surface of the ceramic substrate. Here, the aluminum plate and the ceramic substrate were laminated via an Al—Si brazing material foil. Next, heat treatment is performed under the conditions shown in Table 1 to form an Al layer and a metal layer on one surface and the other surface of the ceramic substrate, and a plate made of the Al layer, titanium foil, and metal member is solid phase diffusion bonded Thus, a circuit layer was formed. And the semiconductor element was joined to one side of the circuit layer via the solder material.

  Here, for the aluminum plate to be the Al layer, as described in the first embodiment, two rolled plates made of 4N aluminum having a purity of 99.99 mass% or more are prepared, and the two rolled plates are It laminated | stacked through Al-Si brazing material foil and it heated in the pressurized state. Thereafter, the two rolled plates were separated to obtain two aluminum plates. At this time, by adjusting the heating temperature and the holding time, the Si concentration on the surface (joint surface) in contact with the Al—Si brazing foil of the aluminum plate was adjusted. The Si concentration was determined by measuring the joint surface of the aluminum plate at five points by EPMA quantitative analysis, and taking the average value. The Si concentration was the concentration when the total amount of Al and Si was 100.

  The cross section of the joint between the Al layer and the metal member layer in the circuit layer of the power module thus manufactured was observed to confirm the presence or absence of the Al—Ti—Si layer. Furthermore, the heat cycle test was done with respect to the power module, and the joining rate of the joined part between the Al layer and the metal member layer after the test was measured. Moreover, the initial joining rate (joining rate before a heat cycle test) of the junction part of Al layer and a metal member layer was also measured. The specific procedure for evaluation is shown below.

(Cross section observation)
The cross section of the circuit layer was subjected to ion etching using a cross section polisher (SM-09010 manufactured by JEOL Ltd.) with an ion acceleration voltage of 5 kV, a processing time of 14 hours, and a protrusion amount from the shielding plate of 100 μm, and then a scanning The joining part of the Al layer (aluminum member) and the metal member layer (metal member) was observed using an electron microscope (SEM). Also, the composition of the joint is analyzed using an EPMA analyzer, and an Al—Ti—Si layer in which Si is dissolved in Al ₃ Ti is formed at the joint interface between the Ti layer and the Al layer. I confirmed.

(Heat cycle test)
The heat cycle test is performed by applying a heat cycle of −40 ° C. ← → 125 ° C. to the power module. In this example, this heat cycle was performed 4000 times.
The bonding rate at the interface between the Al layer and the metal member layer before and after the heat cycle test was measured.

(Joint rate evaluation of the joint between the Al layer and the metal member layer)
The power module before and after the heat cycle test was evaluated using an ultrasonic flaw detector for the joint ratio of the joint between the Al layer and the metal member layer, 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 Al layer. Since peeling is indicated by a white part in the ultrasonic flaw detection image, the area of the white part is defined as a peeling area.
Bonding rate (%) = {(initial bonding area) − (peeling area)} / (initial bonding area) × 100
The results of the above evaluation are shown in Table 1.

In Comparative Example 1 in which the Si concentration on the bonding surface was 0.01 mass%, which was lower than the range of the present invention, the Al-Ti-Si layer was not formed, and the bonding rate after the heat cycle test was greatly reduced. . On the other hand, in Comparative Example 2 in which the Si concentration on the bonding surface was 2.0 mass%, which was higher than the range of the present invention, the bonding rate after the heat cycle test was significantly reduced.
On the other hand, in Examples 1 to 6 of the present invention in which the Si concentration on the bonding surface was within the range of 0.03 mass% or more and 1.0 mass% or less, the initial bonding rate was as high as 98% or more, and after the heat cycle test The bonding rate remained high, and it was confirmed that the power module had high bonding reliability.

10, 110, 210 Power module substrate 11 Ceramic substrate (ceramic member)
12 Circuit layer (joint)
12A Al layer (aluminum member)
12B Cu layer (metal member)
15, 115, 215 Ti layer 16, 116, 216 Al-Ti-Si layer 16A, 116A, 216A First Al-Ti-Si layer 16B, 116B, 216B Second Al-Ti-Si layer 25, 125, 225 Titanium Foil (Ti material)
113 Metal layer (joint)
113A Al layer (aluminum member)
113B Cu layer (metal member)
213 Metal layer (aluminum member)
231 Heat sink (metal member)

Claims (7)

A method for manufacturing a power module substrate comprising: an insulating layer; and a circuit layer formed on one surface of the insulating layer,
The circuit layer is composed of a joined body in which an aluminum layer that is an aluminum member made of aluminum and a metal member layer that is a metal member made of copper, nickel, or silver are joined,
The Si concentration at the joint surface of the aluminum member is in the range of 0.03 mass% to 1.0 mass%,
Laminating the aluminum member on one surface of the insulating layer, interposing a Ti material between the aluminum member and the metal member, laminating the aluminum member and the metal member,
The laminated insulating layer, the aluminum member, and the metal member are heated to join the insulating layer and the aluminum member, and the aluminum member and the Ti material, and the Ti material and the metal member are fixed. The circuit layer is formed by phase diffusion bonding , the bonding between the insulating layer and the aluminum member, the solid phase diffusion bonding between the aluminum member and the Ti material, and the Ti material. A method for manufacturing a power module substrate, wherein solid phase diffusion bonding with the metal member is simultaneously performed . A method of manufacturing a power module substrate comprising: an insulating layer; a circuit layer formed on one surface of the insulating layer; and a metal layer formed on the other surface of the insulating layer,
The metal layer is composed of a joined body in which an aluminum layer that is an aluminum member made of aluminum and a metal member layer that is a metal member made of copper, nickel, or silver are joined,
The Si concentration at the joint surface of the aluminum member is in the range of 0.03 mass% to 1.0 mass%,
Laminating the aluminum member on the other surface of the insulating layer, interposing the Ti material between the aluminum member and the metal member, laminating the aluminum member and the metal member,
The laminated insulating layer, the aluminum member, and the metal member are heated to join the insulating layer and the aluminum member, and the aluminum member and the Ti material, and the Ti material and the metal member are fixed. The metal layer is formed by phase diffusion bonding , the bonding between the insulating layer and the aluminum member, the solid phase diffusion bonding between the aluminum member and the Ti material, and the Ti material. A method for manufacturing a power module substrate, wherein solid phase diffusion bonding with the metal member is simultaneously performed . By the solid phase diffusion bonding, the Ti layer located on the metal member side, the Ti layer, and the aluminum member are located at the joint portion between the aluminum member and the metal member, and Al ₃ Ti is replaced with Si. The method for producing a power module substrate according to claim 1, wherein an Al—Ti—Si layer in which is dissolved.   The Al-Ti-Si layer is formed on the first Al-Ti-Si layer formed on the Ti layer side and on the aluminum member side, and has a lower Si concentration than the first Al-Ti-Si layer. The method for manufacturing a power module substrate according to claim 3, further comprising: a second Al—Ti—Si layer. A power with a heat sink comprising: an insulating layer; a circuit layer formed on one surface of the insulating layer; a metal layer formed on the other surface of the insulating layer; and a heat sink bonded to the metal layer. A method of manufacturing a module substrate,
One of the metal layer and the heat sink is an aluminum member made of aluminum, and the other of the metal layer and the heat sink is a metal member made of copper, nickel, or silver,
The Si concentration at the joint surface of the aluminum member is in the range of 0.03 mass% to 1.0 mass%,
The aluminum member or the metal member to be the metal layer is laminated on the other surface of the insulating layer, a Ti material is interposed between the metal member or the heat sink made of the aluminum member, and the aluminum member and Laminating the metal member,
The laminated aluminum member and the metal member are heated to join the aluminum member or the metal member to be the insulating layer and the metal layer, and the aluminum member and the Ti material, and the Ti material and the metal It is configured to join the metal layer and the heat sink by solid-phase diffusion bonding each of the members, the bonding of the insulating layer and the aluminum member or the metal member to be the metal layer, A method for manufacturing a substrate for a power module with a heat sink , wherein a solid phase diffusion bonding between an aluminum member and the Ti material and a solid phase diffusion bonding between the Ti material and the metal member are simultaneously performed . By the solid phase diffusion bonding, the Ti layer located on the metal member side, the Ti layer, and the aluminum member are located at the joint portion between the aluminum member and the metal member, and Al ₃ Ti is replaced with Si. The method for producing a power module substrate with a heat sink according to claim 1, wherein an Al—Ti—Si layer in which is dissolved.   The Al-Ti-Si layer is formed on the first Al-Ti-Si layer formed on the Ti layer side and on the aluminum member side, and has a lower Si concentration than the first Al-Ti-Si layer. A method for manufacturing a power module substrate with a heat sink according to claim 6, further comprising: a second Al—Ti—Si layer.

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