JP2019169605A - Insulative circuit board - Google Patents

Abstract

To provide an insulative circuit board which is superior in bondability with a semiconductor device, and which enables the suppression of delamination at a bonding interface of an aluminum layer and a copper layer at the time of ultrasonic wave bonding as to a circuit layer arranged by bonding the aluminum layer made of aluminum or aluminum alloy and the copper layer made of copper or copper alloy to each other by solid-phase diffusion.SOLUTION: A circuit layer 20 has an aluminum layer 21 and a copper layer 22. In a face of the circuit layer 20 on a side opposite to an insulative layer 11, a device mount area 20A where a semiconductor device 3 is mounted and an ultrasonic wave bonding region 20B where another member is bonded by means of ultrasonic waves are formed. A product t1×H1 of a thickness t1 and a rigidity H1 of a copper layer 22A in the device mount area 20A, and a product t2×H2 of a thickness t2 and a rigidity H2 of a copper layer 22B in the ultrasonic wave bonding region 20B are different from each other.SELECTED DRAWING: Figure 1

Description

  In the present invention, a circuit layer having an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy bonded to the aluminum layer by solid phase diffusion bonding is formed on one surface of the insulating layer. The present invention relates to an insulating circuit board.

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, and as a substrate on which this is mounted, for example, aluminum nitride (AlN), alumina Conventionally, an insulating circuit board including a ceramic substrate made of (Al ₂ O ₃ ) and 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 has been. 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, an insulating circuit board in which a circuit layer and a metal layer made of aluminum or an aluminum alloy are formed on one surface and the other surface of a ceramic substrate, and a solder material on the circuit layer And a semiconductor element joined through the structure.
A heat sink is bonded to the metal layer side of the insulating circuit board, and heat transferred from the semiconductor element to the insulating circuit board side is dissipated to the outside through the heat sink.

  By the way, when the circuit layer and the metal layer are made of aluminum or an aluminum alloy as in the power module described in Patent Document 1, an aluminum oxide film is formed on the surface of the circuit layer and the metal layer. There was a problem that an element and a heat sink could not be joined.

  Therefore, Patent Document 2 proposes an insulated circuit board in which a circuit layer and a metal layer have a laminated structure of an aluminum layer and a copper layer. In this insulated circuit board, since the copper layer is disposed on the surface of the circuit layer and the metal layer, the semiconductor element and the heat sink can be satisfactorily bonded using a solder material. For this reason, the thermal resistance in the stacking direction is reduced, and the heat generated from the semiconductor element can be efficiently transmitted to the heat sink side.

Japanese Patent No. 3171234 JP 2014-160799 A

By the way, in the circuit layer of the above-mentioned insulated circuit board, while a semiconductor element is mounted, members, such as a terminal material, may be ultrasonically joined.
Here, as described in Patent Document 2, in a circuit layer formed by solid phase diffusion bonding of an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy, at the time of ultrasonic bonding, copper is used. The layer was deformed, and peeling sometimes occurred at the bonding interface between the aluminum layer and the copper layer.
On the other hand, in order to suppress the deformation of the copper layer at the time of ultrasonic bonding, when the copper layer is formed thick, the difference in thermal expansion coefficient with the semiconductor element becomes large, and the bondability with the semiconductor element is increased. There was a risk of decline.

  The present invention has been made in view of the circumstances described above, and in a circuit layer formed by solid phase diffusion bonding of an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy, a semiconductor element and It is an object of the present invention to provide an insulated circuit board that is excellent in bonding property and can suppress peeling at a bonding interface between an aluminum layer and a copper layer during ultrasonic bonding.

  In order to solve the above-described problems, an insulated circuit board according to the present invention is an insulated circuit board including an insulating layer and a circuit layer formed on one surface of the insulating layer, and the circuit layer is made of aluminum. Or an aluminum layer made of an aluminum alloy and a copper layer made of copper or a copper alloy bonded to the aluminum layer, and a semiconductor layer is provided on the surface of the circuit layer facing away from the insulating layer. An element mounting region where the element is mounted and an ultrasonic bonding region where other members are ultrasonically bonded are formed, and the product t1 of the thickness t1 and the hardness H1 of the copper layer in the element mounting region. It is characterized in that xH1 and a product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region are different from each other.

  According to the insulated circuit board having this configuration, the element mounting area where the semiconductor element is mounted and the ultrasonic bonding area where other members are ultrasonically bonded to the surface of the circuit layer facing away from the insulating layer. The product t1 × H1 of the thickness t1 and the hardness H1 of the copper layer in the element mounting region and the product of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region Since t2 × H2 are different from each other, a copper layer having a structure suitable for each of the element mounting region and the ultrasonic bonding region can be formed, the bonding reliability with the semiconductor element is excellent, and the ultrasonic wave It is possible to suppress the occurrence of isolation at the bonding interface between the aluminum layer and the copper layer at the time of bonding.

Here, in the insulated circuit board of the present invention, the product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region is equal to the thickness t1 and the hardness of the copper layer in the element mounting region. It is preferable to be larger than the product t1 × H1 of the height H1.
In this case, in the ultrasonic bonding region, by ensuring the rigidity of the copper layer, the deformation of the copper layer during ultrasonic bonding can be suppressed, and the occurrence of peeling at the bonding interface between the aluminum layer and the copper layer can be suppressed. Is possible. Further, in the element mounting region, the difference in thermal expansion coefficient with the semiconductor element can be suppressed, and the bonding property with the semiconductor element can be ensured.

In the insulated circuit board of the present invention, it is preferable that a product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region is in a range of 10 or more and 110 or less.
In this case, since the product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region is in the range of 10 or more and 110 or less, the rigidity of the copper layer in the ultrasonic bonding region is sufficient. It is possible to reliably prevent the occurrence of isolation at the bonding interface between the aluminum layer and the copper layer during ultrasonic bonding.

Furthermore, in the insulated circuit board of the present invention, the thickness t1 of the copper layer in the element mounting region and the thickness t2 of the copper layer in the ultrasonic bonding region may be different from each other.
In this case, the thickness t1 of the copper layer in the element mounting region and the thickness t2 of the copper layer in the ultrasonic bonding region are configured to be different from each other, thereby forming the copper layer in the element mounting region. The product t1 × H1 of the thickness t1 and the hardness H1 and the product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region can be configured to be different from each other. Become.

In the insulated circuit board of the present invention, in the ultrasonic bonding region, the hardness H1 of the copper layer in the element mounting region and the hardness H2 of the copper layer in the ultrasonic bonding region are different from each other. It is good also as a structure.
In this case, the copper layer hardness in the element mounting area is configured to be different from the hardness H1 of the copper layer in the element mounting area and the hardness H2 of the copper layer in the ultrasonic bonding area. The product t1 × H1 of the thickness t1 and the hardness H1 and the product t2 × H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region can be configured to be different from each other. Become.

  According to the present invention, in a circuit layer formed by solid phase diffusion bonding of an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy, the bonding with a semiconductor element is excellent and ultrasonic bonding is performed. It is possible to provide an insulated circuit board capable of suppressing peeling at the joint interface between the aluminum layer and the copper layer.

It is a schematic explanatory drawing of the power module provided with the insulated circuit board concerning 1st embodiment of this invention. It is a flowchart explaining the manufacturing method of the insulated circuit board which concerns on 1st embodiment. It is a schematic explanatory drawing of the manufacturing method of the insulated circuit board which concerns on 1st embodiment. It is a schematic explanatory drawing of the power module provided with the insulated circuit board which concerns on 2nd embodiment of this invention. It is a flowchart explaining the manufacturing method of the insulated circuit board which concerns on 2nd embodiment. It is a schematic explanatory drawing of the manufacturing method of the insulated circuit board which concerns on 2nd embodiment. It is a schematic explanatory drawing of the power module provided with the insulated circuit board which concerns on 3rd embodiment of this invention. It is a flowchart explaining the manufacturing method of the insulated circuit board which concerns on 3rd embodiment. It is a schematic explanatory drawing of the manufacturing method of the insulated circuit board 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 insulated circuit board 10 which is 1st embodiment of this invention, and the power module 1 using this insulated circuit board 10 are shown.

  A power module 1 shown in FIG. 1 includes an insulated circuit board 10, a semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the insulated circuit board 10 via a first solder layer 2, and an insulated circuit board. 10 is provided with a terminal material 5 ultrasonically bonded to one surface (upper surface in FIG. 1), and a heat sink 61 bonded to the lower side of the insulating circuit board 10 via a second solder layer 8.

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

  The terminal material 5 is comprised with the metal excellent in electroconductivity, and is made into the lead frame material which consists of copper or a copper alloy in this embodiment.

  The heat sink 61 is for dissipating heat on the insulated circuit board 10 side. The heat sink 61 is made of copper or a copper alloy. In the present embodiment, the heat sink 61 is a heat sink made of oxygen-free copper. The second solder layer 8 that joins the insulating circuit board 10 and the heat sink 61 is, for example, a Sn-Ag-based, Sn-Cu-based, Sn-In-based, or Sn-Ag-Cu-based solder material (so-called lead-free solder material). ).

  The insulating circuit board 10 includes a ceramic substrate 11 constituting an insulating layer, a circuit layer 20 disposed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11, and the other surface of the ceramic substrate 11 (FIG. 1). And a metal layer 30 disposed on the lower surface.

The ceramic substrate 11 is made of ceramics such as silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ) and the like that are excellent in insulation and heat dissipation. In the present embodiment, the ceramic substrate 11 is made of aluminum nitride (AlN) that is particularly excellent in heat dissipation. The thickness of the ceramic substrate 11 is set, for example, within a range of 0.2 mm or more and 1.5 mm or less, and is set to 0.635 mm in the present embodiment.

As shown in FIG. 1, the circuit layer 20 includes an aluminum layer 21 disposed on one surface of the ceramic substrate 11 and a copper layer 22 stacked on one surface of the aluminum layer 21. Yes.
In addition, the thickness of the aluminum layer 21 in the circuit layer 20 is set in 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.
As shown in FIG. 3, the aluminum layer 21 is formed by joining an aluminum plate 41 made of aluminum and an aluminum alloy to one surface of the ceramic substrate 11.
In this embodiment, the aluminum plate 41 to be the aluminum layer 21 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more.

In the circuit layer 20, an element mounting area 20 </ b> A where the semiconductor element 3 is mounted and an ultrasonic bonding area 20 </ b> B where the terminal material 5 is ultrasonically bonded are formed on the surface facing away from the ceramic substrate 11. ing.
The copper layer 22 of the circuit layer 20 is configured differently between the first copper layer 22A corresponding to the semiconductor element mounting region 20A and the second copper layer 22B corresponding to the ultrasonic bonding region 20B. ing.

Specifically, the product t1 × H1 of the thickness t1 and the hardness H1 of the first copper layer 22A in the element mounting region 20A, and the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B. The products t2 × H2 are configured to be different from each other.
In the present embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B is the thickness t1 and the hardness H1 of the first copper layer 22A in the element mounting region 20A. It is comprised so that it may become larger than the product t1xH1.
In this embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B is in the range of 10 to 110.

In the present embodiment, as shown in FIG. 1, the thickness t1 of the first copper layer 22A and the thickness t2 of the second copper layer 22B are the same, and the second copper layer 22B and the first copper layer 22A is made of a different material, and the hardness H2 of the second copper layer 22B is harder than the hardness H1 of the first copper layer 22A.
Specifically, the thickness of the copper layer 22 (the thickness t1 of the first copper layer 22A and the thickness t2 of the second copper layer 22B) is set within a range of 0.1 mm to 1.0 mm. In this embodiment, it is set to 0.4 mm.
The Vickers hardness H2 of the second copper layer 22B is in the range of 50 Hv to 200 Hv, and the Vickers hardness H1 of the first copper layer 22A is in the range of 20 Hv to 50 Hv.

As shown in FIG. 3, the copper layer 22 (first copper layer 22 </ b> A and second copper layer 22 </ b> B) has an aluminum layer 21 and a copper plate 42 (first copper plate 42 </ b> A and second copper plate 42 </ b> B) made of copper or a copper alloy. It is formed by joining.
Here, in the present embodiment, the Vickers hardness of the second copper plate 42B constituting the second copper layer 22B in the ultrasonic bonding region 20B is the first copper plate 42A constituting the first copper layer 22A in the element mounting region 20A. It is said to be harder than Vickers hardness.

  Specifically, the first copper plate 42A constituting the first copper layer 22A in the element mounting region 20A is a rolled plate made of pure copper such as oxygen-free copper having a copper purity of 99.99 mass% or more, for example. Yes. Further, the second copper plate 42B constituting the second copper layer 22B in the ultrasonic bonding region 20B has a copper alloy such as Zr-containing copper containing, for example, a Zr content in the range of 0.01 mass% to 0.1 mass%. It is made into the rolled board which consists of.

Here, the aluminum layer 21 and the copper layer 22 (the first copper layer 22A and the second copper layer 22B) are respectively solid-phase diffusion bonded.
An intermetallic compound layer made of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 21 and the copper layer 22 (the first copper layer 22A and the second copper layer 22B). The compound layer is configured by laminating a plurality of intermetallic compounds of a plurality of phases.

As shown in FIG. 1, the metal layer 30 includes an aluminum layer 31 disposed on the other surface of the ceramic substrate 11 and a copper layer 32 laminated on the other surface of the aluminum layer 31. Yes.
In addition, the thickness of the aluminum layer 31 in the metal layer 30 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.
Moreover, the thickness of the copper layer 32 in the metal layer 30 is set within a range of 0.1 mm or more and 6.0 mm or less, and is set to 0.4 mm in the present embodiment.

As shown in FIG. 3, the aluminum layer 31 in the metal layer 30 is formed by joining an aluminum plate 51 made of aluminum and an aluminum alloy to the other surface of the ceramic substrate 11.
In the present embodiment, the aluminum plate 51 to be the aluminum layer 31 in the metal layer 30 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more. .

As shown in FIG. 3, the copper layer 32 in the metal layer 30 is formed by joining a copper plate 52 made of copper or a copper alloy to the aluminum layer 31.
In the present embodiment, the copper plate 52 constituting the copper layer 32 in the metal layer 30 is a rolled plate of oxygen-free copper.

Here, the aluminum layer 31 and the copper layer 32 in the metal layer 30 are solid phase diffusion bonded.
Note that an intermetallic compound layer made of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 31 and the copper layer 32, and this intermetallic compound layer is formed by laminating intermetallic compounds of a plurality of phases. It has been configured.

  Next, the manufacturing method of the insulated circuit board 10 which is this embodiment is demonstrated with reference to FIG.2 and FIG.3.

(Aluminum layer forming step S01)
As shown in FIG. 3, an aluminum plate 41 to be the aluminum layer 21 is laminated on one surface of the ceramic substrate 11 via an Al—Si based brazing material foil 46, and on the other surface of the ceramic substrate 11. Then, an aluminum plate 51 to be the aluminum layer 31 is laminated via an Al—Si brazing material foil 56. In this embodiment, Al-8 mass% Si alloy foil having a thickness of 10 μm is used as the Al—Si brazing material foils 46 and 56.

And it arrange | positions in a vacuum heating furnace in the state pressurized (pressure 1-35kgf / cm < ² > (0.1-3.5MPa)) in the lamination direction, it heats, the aluminum plate 41 and the ceramic substrate 11 are joined. An aluminum layer 21 is formed. Further, the ceramic substrate 11 and the aluminum plate 51 are joined to form the aluminum layer 31.
Here, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is in the range of 600 ° C. to 650 ° C., and the holding time at the heating temperature is 15 minutes to 180 minutes. It is preferable to set within the range.

(Copper plate lamination step S02)
Next, the first copper plate 42A to be the first copper layer 22A and the second copper plate 42B to be the second copper layer 22B are stacked in parallel on one surface side (the upper side in FIG. 3) of the aluminum layer 21. To do.
Moreover, the copper plate 52 used as the copper layer 32 is laminated | stacked on the other surface side (lower side in FIG. 3) of the aluminum layer 31, and a laminated body is formed.
Here, as described above, the first copper plate 42A is a rolled plate made of oxygen-free copper, and the second copper plate 42B contains a Zr content in the range of 0.01 mass% to 0.1 mass%. It is a rolled plate of Zr-containing copper.
The joining surfaces of the aluminum layers 21 and 31, the first copper plate 42A, the second copper plate 42B, and the copper plate 52 are smoothed by removing the scratches on the surfaces in advance.

(Solid phase diffusion bonding step S03)
Next, the laminated body is pressurized (pressure 3 to 35 kgf / cm ² (0.1 to 3.5 MPa)) and heated in the laminating direction to heat the aluminum layer 21, the first copper plate 42A, and the second copper plate. 42B, the aluminum layer 31 and the copper plate 52 are respectively solid phase diffusion bonded.
Here, in the solid phase diffusion bonding step S03, the heating temperature is preferably set in a range of 400 ° C. or higher and lower than 548 ° C., and the holding time at the heating temperature is preferably set in a range of 5 minutes or more and 240 minutes or less.

  As described above, the insulated circuit board 10 according to the present embodiment is manufactured.

(Heat sink joining step S04)
Next, the copper layer 32 of the metal layer 30 and the heat sink 61 are laminated via a solder material, and soldered in a reduction furnace.

(Terminal material joining step S05)
Next, the terminal material 5 is ultrasonically bonded to the ultrasonic bonding region 20 </ b> B (second copper layer 22 </ b> B) of the circuit layer 20.

(Semiconductor element bonding step S06)
Next, the semiconductor element 3 is stacked on the element mounting region 20A (first copper layer 22A) of the circuit layer 20 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 insulated circuit board 10 according to the present embodiment configured as described above, the element mounting region 20A on which the semiconductor element 3 is mounted on the surface of the circuit layer 20 facing away from the ceramic substrate 11, An ultrasonic bonding region 20B to which the terminal material 5 is ultrasonically bonded, and a product t1 × H1 of the thickness t1 and the hardness H1 of the first copper layer 22A in the element mounting region 20A, and ultrasonic bonding. Since the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the region 20B is configured to be different from each other, the element mounting region 20A and the ultrasonic bonding region 20B are suitable for each. The copper layer (the first copper layer 22A and the second copper layer 22B) can be formed, has excellent bonding reliability with the semiconductor element 3, and the aluminum layer 21 and the second copper layer 22B at the time of ultrasonic bonding. Joining with It is possible to suppress the occurrence of isolation at the interface.

  In the present embodiment, specifically, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B is the thickness of the first copper layer 22A in the element mounting region 20A. Since it is configured to be larger than the product t1 × H1 of t1 and hardness H1, in the ultrasonic bonding region 20B, the second copper layer 22B has a second rigidity at the time of ultrasonic bonding by ensuring the rigidity. The deformation of the copper layer 22B can be suppressed, and the occurrence of peeling at the bonding interface between the aluminum layer 21 and the second copper layer 22B can be suppressed. Further, in the element mounting region 20 </ b> A, the difference in thermal expansion coefficient with the semiconductor element 3 can be kept small, and the bonding property with the semiconductor element 3 can be ensured.

  Furthermore, in this embodiment, since the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B is in the range of 10 to 110, the ultrasonic bonding region Can sufficiently ensure the rigidity of the second copper layer 22B, and can reliably suppress the occurrence of isolation at the bonding interface between the aluminum layer 21 and the second copper layer 22B during ultrasonic bonding.

  In the present embodiment, the thickness t1 of the first copper layer 22A and the thickness t2 of the second copper layer 22B are the same, and the hardness H2 of the second copper layer 22B is the same as that of the first copper layer 22A. More specifically, the Vickers hardness H2 of the second copper layer 22B is in the range of 50 Hv to 200 Hv, and the Vickers hardness H1 of the first copper layer 22A is 20 Hv. Since it is within the range of 50 Hv or less, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 22B in the ultrasonic bonding region 20B is the thickness of the first copper layer 22A in the element mounting region 20A. It can be surely made larger than the product t1 × H1 of the thickness t1 and the hardness H1.

(Second embodiment)
Next, an insulated circuit board 110 according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment, and detailed description is abbreviate | omitted.
FIG. 4 shows an insulated circuit board 110 according to the second embodiment of the present invention, and a power module 101 using the insulated circuit board 110.

  A power module 101 shown in FIG. 4 includes an insulating circuit board 110, a semiconductor element 3 bonded to one surface (upper surface in FIG. 4) of the insulating circuit board 110 via a first solder layer 2, and an insulating circuit board. The terminal material 5 is ultrasonically bonded to one surface (upper surface in FIG. 4) of 110, and the heat sink 61 is bonded to the lower side of the insulating circuit substrate 110 via the second solder layer 8.

  The insulating circuit board 110 includes a ceramic substrate 11 constituting an insulating layer, a circuit layer 120 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 4), and the other surface of the ceramic substrate 11 (FIG. 4). And a metal layer 130 disposed on the lower surface.

As shown in FIG. 4, the circuit layer 120 includes an aluminum layer 121 disposed on one surface of the ceramic substrate 11, and a copper layer 122 stacked on one surface of the aluminum layer 121. Yes.
In addition, the thickness of the aluminum layer 121 in the circuit layer 120 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.
As shown in FIG. 6, the aluminum layer 121 is formed by joining an aluminum plate 141 made of aluminum and an aluminum alloy to one surface of the ceramic substrate 11.
In this embodiment, the aluminum plate 141 to be the aluminum layer 121 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more.

An element mounting area 120A where the semiconductor element 3 is mounted and an ultrasonic bonding area 120B where the terminal material 5 is ultrasonically bonded are formed on the surface of the circuit layer 120 facing away from the ceramic substrate 11. Yes.
The copper layer 122 of the circuit layer 120 is configured differently between the first copper layer 122A corresponding to the semiconductor element mounting region 120A and the second copper layer 122B corresponding to the ultrasonic bonding region 120B. ing.

Specifically, the product t1 × H1 of the thickness t1 and the hardness H1 of the first copper layer 122A in the element mounting region 120A, and the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B. The products t2 × H2 are configured to be different from each other.
In the present embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is the thickness t1 and the hardness H1 of the first copper layer 122A in the element mounting region 120A. It is comprised so that it may become larger than the product t1xH1.
In this embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is in the range of 10 or more and 110 or less.

In the present embodiment, as shown in FIG. 4, the first copper layer 122A and the second copper layer 122B are composed of the same member, and the hardness H1 of the first copper layer 122A and the hardness of the second copper layer 122B. The thickness H2 is the same, and the thickness t2 of the second copper layer 122B is thicker than the thickness t1 of the first copper layer 122A.
Specifically, the Vickers hardness of the copper layer 122 (Vickers hardness H1 of the first copper layer 122A and Vickers hardness H2 of the second copper layer 122B) is in the range of 20 Hv to 50 Hv, and this embodiment Then, it is set to 40 Hv.
Then, the thickness t1 of the first copper layer 122A corresponding to the element mounting region 120A is in the range of 0.1 mm to 0.6 mm, and the thickness t2 of the second copper layer 122B corresponding to the ultrasonic bonding region 120B. Is in the range of 0.3 mm or more and 1.5 mm or less.

  As shown in FIG. 6, the copper layer 122 (the first copper layer 122 </ b> A and the second copper layer 122 </ b> B) is made of copper or a copper alloy, and a deformed copper plate 142 having a locally different thickness is joined to the aluminum layer 121. Is formed.

Here, the aluminum layer 121 and the copper layer 122 are solid phase diffusion bonded.
Note that an intermetallic compound layer made of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 121 and the copper layer 122, and this intermetallic compound layer is formed by laminating intermetallic compounds of a plurality of phases. It has been configured.

As shown in FIG. 4, the metal layer 130 includes an aluminum layer 131 disposed on the other surface of the ceramic substrate 11 and a copper layer 132 laminated on the other surface of the aluminum layer 131. Yes.
In addition, the thickness of the aluminum layer 131 in the metal layer 130 is set within a range of 0.1 mm to 3.0 mm, and is set to 0.6 mm in the present embodiment.
Further, the thickness of the copper layer 132 in the metal layer 130 is set in a range of 0.1 mm or more and 6.0 mm or less, and is set to 0.6 mm in the present embodiment.

As shown in FIG. 6, the aluminum layer 131 in the metal layer 130 is formed by joining an aluminum plate 151 made of aluminum and an aluminum alloy to the other surface of the ceramic substrate 11.
In this embodiment, the aluminum plate 151 to be the aluminum layer 131 in the metal layer 130 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more. .

As shown in FIG. 6, the copper layer 132 in the metal layer 130 is formed by bonding a copper plate 152 made of copper or a copper alloy to the aluminum layer 131.
In the present embodiment, the copper plate 152 constituting the copper layer 132 in the metal layer 130 is a rolled plate of oxygen-free copper.

Here, the aluminum layer 131 and the copper layer 132 in the metal layer 130 are solid phase diffusion bonded.
Note that an intermetallic compound layer made of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 131 and the copper layer 132, and this intermetallic compound layer is formed by laminating intermetallic compounds of a plurality of phases. It has been configured.

  Next, the manufacturing method of the insulated circuit board 110 which is this embodiment is demonstrated with reference to FIG.5 and FIG.6.

(Aluminum layer forming step S101)
As shown in FIG. 6, an aluminum plate 141 to be an aluminum layer 121 is laminated on one surface of the ceramic substrate 11 via an Al—Si based brazing material foil 146 and on the other surface of the ceramic substrate 11. Then, an aluminum plate 151 to be the aluminum layer 131 is laminated via an Al—Si brazing material foil 156. In this embodiment, an Al-8 mass% Si alloy foil having a thickness of 10 μm is used as the Al—Si based brazing material foils 146 and 156.

And it arrange | positions in a vacuum heating furnace in the state pressurized (the pressure 1-35kgf / cm < ² > (0.1-3.5MPa)) in the lamination direction, it heats, the aluminum plate 141 and the ceramic substrate 11 are joined. An aluminum layer 121 is formed. In addition, the aluminum layer 131 is formed by bonding the ceramic substrate 11 and the aluminum plate 151.
Here, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is in the range of 600 ° C. to 650 ° C., and the holding time at the heating temperature is 15 minutes to 180 minutes. It is preferable to set within the range.

(Copper plate lamination step S102)
Next, a copper plate 142 to be the copper layer 122 is laminated on one surface side of the aluminum layer 121 (upper side in FIG. 6). Here, as shown in FIG. 6, the copper plate 142 is a deformed copper plate having locally different thicknesses. Here, since the thickness of the copper plate 142 is locally different, the height is matched by arranging the spacer 148.
Moreover, the copper plate 152 used as the copper layer 132 is laminated | stacked on the other surface side (lower side in FIG. 6) of the aluminum layer 131, and a laminated body is formed.
The joint surfaces of the aluminum layers 121 and 131 and the copper plates 142 and 152 are smoothed by removing scratches on the surfaces in advance.

(Solid phase diffusion bonding step S103)
Next, the above-mentioned laminate is pressurized (pressure 3 to 35 kgf / cm ² (0.1 to 3.5 MPa)) and heated in the laminating direction to heat the aluminum layer 121 and the copper plate 142, the aluminum layer 131 and the copper plate. 152 are bonded to each other by solid phase diffusion bonding. At this time, since the thickness of the copper plate 142 is locally different, the spacer 148 is arranged to press the entire copper plate 142 toward the aluminum layer 121 side.
Here, in the solid phase diffusion bonding step S103, it is preferable that the heating temperature is set in a range of 400 ° C. or more and less than 548 ° C., and the holding time at the heating temperature is set in a range of 5 minutes or more and 240 minutes or less.

  As described above, the insulated circuit board 110 according to the present embodiment is manufactured.

(Heat sink joining step S104)
Next, the copper layer 132 of the metal layer 130 and the heat sink 61 are laminated via a solder material, and soldered in a reduction furnace.

(Terminal material joining step S105)
Next, the terminal material 5 is ultrasonically bonded to the ultrasonic bonding region 120 </ b> B (second copper layer 122 </ b> B) of the circuit layer 120.

(Semiconductor element bonding step S106)
Next, the semiconductor element 3 is stacked on the element mounting region 120A (first copper layer 122A) of the circuit layer 120 via a solder material, and solder-bonded in a reduction furnace.
As described above, the power module 101 according to the present embodiment is manufactured.

  According to the insulated circuit board 110 according to the present embodiment configured as described above, as in the first embodiment, the product t1 of the thickness t1 and the hardness H1 of the first copper layer 122A in the element mounting region 120A. Since the product t2 × H2 of × H1 and the thickness t2 and hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is different from each other, the element mounting region 120A and the ultrasonic bonding region 120B , The copper layer (the first copper layer 122A and the second copper layer 122B) having a structure suitable for each can be formed, the bonding reliability with the semiconductor element 3 is excellent, and the aluminum layer at the time of ultrasonic bonding It is possible to suppress the occurrence of isolation at the bonding interface between 121 and the second copper layer 122B.

  In the present embodiment, specifically, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is the thickness of the first copper layer 122A in the element mounting region 120A. Since it is configured to be larger than the product t1 × H1 of t1 and hardness H1, in the ultrasonic bonding region 120B, the second copper layer 122B is ensured to be rigid at the second time during ultrasonic bonding. The deformation of the copper layer 122B can be suppressed, and the occurrence of peeling at the bonding interface between the aluminum layer 121 and the second copper layer 122B can be suppressed. Further, in the element mounting region 120 </ b> A, the difference in thermal expansion coefficient with the semiconductor element 3 can be kept small, and the bonding property with the semiconductor element 3 can be ensured.

  Furthermore, in this embodiment, since the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is in the range of 10 to 110, the ultrasonic bonding region Can sufficiently secure the rigidity of the second copper layer 122B, and can reliably suppress the occurrence of isolation at the bonding interface between the aluminum layer 121 and the second copper layer 122B during ultrasonic bonding.

  In the present embodiment, the first copper layer 122A and the second copper layer 22B are composed of the same member, and the hardness H1 of the first copper layer 122A and the hardness H2 of the second copper layer 22B are the same. The thickness t2 of the second copper layer 122B is configured to be thicker than the thickness t1 of the first copper layer 122A. Specifically, the first copper layer corresponding to the element mounting region 120A The thickness t1 of 122A is in the range of 0.1 mm to 0.6 mm, and the thickness t2 of the second copper layer 122B corresponding to the ultrasonic bonding region 120B is in the range of 0.3 mm to 1.5 mm. Therefore, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 122B in the ultrasonic bonding region 120B is equal to the thickness t1 and the hardness H1 of the first copper layer 122A in the element mounting region 120A. Surely larger than the product t1 × H1 it can.

(Third embodiment)
Next, the insulated circuit board 210 which is 3rd embodiment of this invention is demonstrated with reference to attached drawing. In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment and 2nd embodiment, and detailed description is abbreviate | omitted.
FIG. 7 shows an insulated circuit board 210 according to a second embodiment of the present invention and a power module 201 using the insulated circuit board 210.

  A power module 201 shown in FIG. 7 includes an insulating circuit board 210, a semiconductor element 3 bonded to one surface (upper surface in FIG. 7) of the insulating circuit board 210 via a first solder layer 2, and an insulating circuit board. The terminal material 5 is ultrasonically bonded to one surface of 210 (the upper surface in FIG. 7), and the heat sink 61 is bonded to the lower side of the insulating circuit board 210 via the second solder layer 8.

  The insulating circuit board 210 includes a ceramic substrate 11 constituting an insulating layer, a circuit layer 220 disposed on one surface (upper surface in FIG. 7) of the ceramic substrate 11, and the other surface of the ceramic substrate 11 (FIG. 7). And a metal layer 230 disposed on the lower surface.

As shown in FIG. 7, the circuit layer 220 includes an aluminum layer 221 disposed on one surface of the ceramic substrate 11, and a copper layer 222 laminated on one surface of the aluminum layer 221. Yes.
Note that the thickness of the aluminum layer 221 in the circuit layer 220 is set in a range of 0.1 mm to 1.0 mm, and is set to 0.4 mm in the present embodiment.
As shown in FIG. 9, the aluminum layer 221 is formed by joining an aluminum plate 241 made of aluminum and an aluminum alloy to one surface of the ceramic substrate 11.
In the present embodiment, the aluminum plate 241 serving as the aluminum layer 221 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more.

An element mounting area 220A on which the semiconductor element 3 is mounted and an ultrasonic bonding area 220B in which the terminal material 5 is ultrasonically bonded are formed on the surface of the circuit layer 220 facing away from the ceramic substrate 11. Yes.
The copper layer 222 of the circuit layer 220 is configured differently between the first copper layer 222A corresponding to the semiconductor element mounting region 220A and the second copper layer 222B corresponding to the ultrasonic bonding region 220B. ing.

Specifically, the product t1 × H1 of the thickness t1 and the hardness H1 of the first copper layer 222A in the element mounting region 220A, and the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B. The products t2 × H2 are configured to be different from each other.
In the present embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B is the thickness t1 and the hardness H1 of the first copper layer 222A in the element mounting region 220A. It is comprised so that it may become larger than the product t1xH1.
In the present embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B is in the range of 10 or more and 110 or less.

In the present embodiment, as shown in FIG. 7, the first copper layer 222A is composed of a single layer, and the second copper layer 222B is composed of a plurality of layers (two layers in the present embodiment). The hardness H1 of the copper layer 222A is different from the hardness H2 of the second copper layer 222B, and the thickness t2 of the second copper layer 222B is thicker than the thickness t1 of the first copper layer 222A. The hardness of the second copper layer 222B is measured on one surface of the second copper layer 222B (the surface to which the terminal material 5 is bonded).
Specifically, the thickness t1 of the first copper layer 222A corresponding to the element mounting region 220A is in the range of 0.1 mm to 0.6 mm, and the second copper layer 222B corresponding to the ultrasonic bonding region 220B is formed. The thickness t2 is in the range of 0.3 mm to 1.5 mm.
Further, the Vickers hardness H2 of the second copper layer 222B is in the range of 50 Hv to 200 Hv, and the Vickers hardness H1 of the first copper layer 222A is in the range of 20 Hv to 50 Hv.

  Specifically, the first copper plate 242A constituting the first copper layer 222A in the element mounting region 220A is a rolled plate made of pure copper such as oxygen-free copper, for example. In addition, the second copper plate 242B laminated on one surface side of the second copper layer 222B in the ultrasonic bonding region 220B has a Zr content of, for example, in a range of 0.01 mass% to 0.1 mass%. The rolled plate is made of a copper alloy such as filled copper.

Here, the aluminum layer 221 and the copper layer 222 are solid phase diffusion bonded.
Note that an intermetallic compound layer composed of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 221 and the copper layer 222, and this intermetallic compound layer is formed by laminating intermetallic compounds of a plurality of phases. It has been configured.

As shown in FIG. 7, the metal layer 230 includes an aluminum layer 231 disposed on the other surface of the ceramic substrate 11, and a copper layer 232 laminated on the other surface of the aluminum layer 231. Yes.
In addition, the thickness of the aluminum layer 231 in the metal layer 230 is set within a range of 0.1 mm to 3.0 mm, and is set to 0.6 mm in the present embodiment.
Further, the thickness of the copper layer 232 in the metal layer 230 is set in a range of 0.1 mm or more and 6.0 mm or less, and is set to 0.6 mm in the present embodiment.

As shown in FIG. 9, the aluminum layer 231 in the metal layer 230 is formed by joining an aluminum plate 251 made of aluminum and an aluminum alloy to the other surface of the ceramic substrate 11.
In the present embodiment, the aluminum plate 251 serving as the aluminum 231 in the metal layer 230 is made of aluminum (2N aluminum) having a purity of 99 mass% or more or aluminum (4N aluminum) having a purity of 99.99 mass% or more.

As shown in FIG. 9, the copper layer 232 in the metal layer 230 is formed by bonding a copper plate 252 made of copper or a copper alloy to the aluminum layer 231.
In the present embodiment, the copper plate 252 constituting the copper layer 232 in the metal layer 230 is a rolled plate of oxygen-free copper.

Here, the aluminum layer 231 and the copper layer 232 in the metal layer 230 are solid phase diffusion bonded.
Note that an intermetallic compound layer made of an intermetallic compound of Cu and Al is formed at the bonding interface between the aluminum layer 231 and the copper layer 232, and this intermetallic compound layer is formed by laminating intermetallic compounds of a plurality of phases. It has been configured.

  Next, the manufacturing method of the insulated circuit board 210 which is this embodiment is demonstrated with reference to FIG.8 and FIG.9.

(Aluminum layer forming step S201)
As shown in FIG. 9, an aluminum plate 241 to be an aluminum layer 221 is laminated on one surface of the ceramic substrate 11 via an Al—Si based brazing foil 246 and on the other surface of the ceramic substrate 11. Then, an aluminum plate 251 to be the aluminum layer 231 is laminated via an Al—Si based brazing material foil 256. In this embodiment, an Al-8 mass% Si alloy foil having a thickness of 10 μm is used as the Al—Si brazing foils 246 and 256.

And it arrange | positions in a vacuum heating furnace in the state pressurized (the pressure 1-35kgf / cm < ² > (0.1-3.5MPa)) in the lamination direction, heats, the aluminum plate 241 and the ceramic substrate 11 are joined. An aluminum layer 221 is formed. Further, the ceramic substrate 11 and the aluminum plate 251 are joined to form the aluminum layer 231.
Here, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is in the range of 600 ° C. to 650 ° C., and the holding time at the heating temperature is 15 minutes to 180 minutes. It is preferable to set within the range.

(Copper plate lamination step S202)
Next, the first copper plate 242A, which is the lower layer of the first copper layer 222A and the second copper layer 222B, and the upper layer of the second copper layer 222B are formed on one surface side of the aluminum layer 221 (upper side in FIG. 9). Two copper plates 242B are laminated. At this time, the region where only the first copper plate 242A is laminated and the region where the first copper plate 242A and the second copper plate 242B are laminated have different thicknesses. Are matched.
Here, the first copper plate 242A is a rolled plate made of oxygen-free copper, and the second copper plate 242B is a rolled Zr-containing copper containing a Zr content in the range of 0.01 mass% to 0.1 mass%. It is a board.
Note that the bonding surfaces of the aluminum layers 221 and 231, the first copper plate 242 </ b> A, the second copper plate 242 </ b> B, and the copper plate 252 are smoothed by removing the scratches on the surfaces in advance.

(Solid phase diffusion bonding step S203)
Next, the laminated body is pressurized (pressure 3 to 35 kgf / cm ² (0.1 to 3.5 MPa)) and heated in the laminating direction to heat the aluminum layer 221, the first copper plate 242A, and the first copper plate. 242A and the second copper plate 242B, the aluminum layer 231 and the copper plate 252 are respectively solid phase diffusion bonded. At this time, the region where only the first copper plate 242A is laminated and the region where the first copper plate 242A and the second copper plate 242B are laminated have different thicknesses. The entire copper plate 242A is configured to be pressed against the aluminum layer 221 side.
Here, in the solid phase diffusion bonding step S203, the heating temperature is preferably set within a range of 400 ° C. or higher and lower than 548 ° C., and the holding time at the heating temperature is preferably set within a range of 5 minutes or longer and 240 minutes or shorter.

  As described above, the insulated circuit board 210 according to the present embodiment is manufactured.

(Heat sink joining step S204)
Next, the copper layer 232 of the metal layer 230 and the heat sink 61 are laminated via a solder material, and are soldered in a reduction furnace.

(Terminal material joining step S205)
Next, the terminal material 5 is ultrasonically bonded to the ultrasonic bonding region 220 </ b> B (second copper layer 222 </ b> B) of the circuit layer 220.

(Semiconductor element bonding step S206)
The semiconductor element 3 is laminated on the element mounting region 220A (first copper layer 222A) of the circuit layer 220 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 insulated circuit board 210 according to the present embodiment configured as described above, the thickness t1 of the first copper layer 222A in the element mounting region 220A and the hardness are the same as in the first and second embodiments. The product t1 × H1 of the thickness H1 and the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B are configured to be different from each other. In the ultrasonic bonding region 220B, copper layers (the first copper layer 222A and the second copper layer 222B) having suitable structures can be formed, the bonding reliability with the semiconductor element 3 is excellent, and the ultrasonic wave It is possible to suppress the occurrence of isolation at the bonding interface between the aluminum layer 221 and the second copper layer 222B at the time of bonding.

  In the present embodiment, specifically, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B is the thickness of the first copper layer 222A in the element mounting region 220A. Since it is configured to be larger than the product t1 × H1 of t1 and hardness H1, in the ultrasonic bonding region 220B, the second copper layer 222B is secured to ensure the second at the time of ultrasonic bonding. The deformation of the copper layer 222B can be suppressed, and the occurrence of peeling at the bonding interface between the aluminum layer 221 and the second copper layer 222B can be suppressed. Further, in the element mounting region 220 </ b> A, the difference in thermal expansion coefficient with the semiconductor element 3 can be suppressed to be small, and the bonding property with the semiconductor element 3 can be ensured.

  Further, in the present embodiment, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B is in the range of 10 or more and 110 or less. Can sufficiently secure the rigidity of the second copper layer 222B, and can reliably suppress the occurrence of isolation at the bonding interface between the aluminum layer 221 and the second copper layer 222B during ultrasonic bonding.

  In the present embodiment, the first copper layer 222A is a single layer, the second copper layer 222B has a two-layer structure, and the hardness H1 and thickness t1 of the first copper layer 222A are Since the structure is different from the hardness H2 and thickness t2 of the two copper layers 122B, the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer 222B in the ultrasonic bonding region 220B is mounted on the element. It can be surely made larger than the product t1 × H1 of the thickness t1 and the hardness H1 of the first copper layer 222A in the region 220A.

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 this embodiment, although it demonstrated as what formed the metal layer which has an aluminum layer and a copper layer, it is not limited to this, The metal layer does not necessarily need to be formed, A metal layer May be composed of a single layer of metal having excellent heat dissipation such as aluminum or aluminum alloy, copper or copper alloy.

Moreover, as an aluminum plate which comprises an aluminum layer, although the aluminum rolled plate of purity 99.99 mass% or more was mentioned as an example and demonstrated, it is not limited to this, Pure aluminum of purity 99 mass% or more, etc. It may be composed of aluminum or an aluminum alloy.
Furthermore, as a copper plate constituting the copper layer and the like, an oxygen-free copper rolled plate and a Zr-containing copper alloy rolled plate have been described as examples, but the present invention is not limited thereto, and other copper or It may be composed of a copper alloy.

In the present embodiment, the power module is configured by mounting the semiconductor element on the insulating circuit board. However, the present invention is not limited to this. For example, an LED module may be configured by mounting LED elements on a circuit layer of an insulated circuit board, or a thermoelectric module may be configured by mounting thermoelectric elements on a circuit layer of an insulated circuit board.
Furthermore, in the present embodiment, the insulating layer is described as being configured with a ceramic substrate. However, the present invention is not limited thereto, and the insulating layer may be configured with resin or the like.

  Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.

Bonded to one surface of the ceramic substrate and one surface of an aluminum plate (37 mm × 37 mm × thickness 0.6 mm) made of a rolled plate of aluminum (4N aluminum) having a purity of 99.99 mass% or more. An aluminum layer was formed.
The joining conditions in the aluminum layer forming step were a pressure load in the stacking direction of 5 kgf / cm ² (0.5 MPa), a heating temperature of 650 ° C., and a holding time at the heating temperature of 30 minutes.

Next, a copper plate is solid phase diffusion bonded to the aluminum layer formed on one surface side of the ceramic substrate, a first copper layer corresponding to the element bonding region, and a second copper layer corresponding to the ultrasonic bonding region, Were created by the method described in the above embodiment.
The structure “1” corresponds to the structure of the first embodiment, and the first copper layer and the second copper layer are formed in parallel on the aluminum layer.
The structure “2” corresponds to the structure of the second embodiment, in which the first copper layer and the second copper layer are formed using deformed copper plates having locally different thicknesses.
“3” in the structure corresponds to the third embodiment, and the first copper layer has a single-layer structure and the second copper layer has a two-layer structure.

  The hardness H1 of the first copper layer and the hardness H2 of the second copper layer use a diamond indenter with a regular pyramid and use a semi-Vickers hardness meter (HSV-30 manufactured by Shimadzu Corporation), JIS Z It was measured by the method specified in 2244. The measurement results are shown in Table 1.

Further, a copper plate (37 mm × 37 mm) made of an oxygen-free copper rolled plate was solid phase diffusion bonded on the aluminum layer formed on the other surface side of the ceramic substrate to form a metal layer.
The bonding conditions in the solid phase diffusion bonding step were a pressure load in the stacking direction of 12 kgf / cm ² (1.2 MPa), a heating temperature of 535 ° C., and a holding time at the heating temperature of 120 minutes.

In Comparative Examples 1 to 3, the element mounting area and the ultrasonic bonding area have the same configuration.
As described above, the insulating circuit boards of the present invention example and the comparative example were manufactured.

  Then, the copper terminal (10 mm × 5 mm × 1 mm thickness) is copied to the ultrasonic bonding region of the obtained insulating circuit board using an ultrasonic metal bonding machine (Ultrasonic Industry Co., Ltd .: 60C-904). Ultrasonic bonding was performed under the condition of an amount of 0.5 mm.

  Moreover, the semiconductor element was solder-joined with respect to the element mounting area | region of the obtained insulated circuit board using the solder material (Cu-99.3 mass% Sn). The soldering conditions were such that the atmosphere was a 3 vol% hydrogen reducing atmosphere, the heating temperature was 300 ° C., and the holding time at the heating temperature was 10 minutes.

  And the joining strength with the copper terminal which carried out ultrasonic joining, and the joining rate in the element joining solder layer after a thermal cycle load were evaluated as follows. The evaluation results are shown in Table 1.

(Joint strength with copper terminal)
Using a push-pull gauge (manufactured by Aiko Engineering Co., Ltd., digital push-pull gauge RX series), the maximum strength until the lead frame peeled from the circuit layer was measured. The measurement was performed 15 times, and the average value was defined as the bonding strength. Then, based on the bonding strength of Comparative Example 1, the bonding strength is 1.4 or more times that of Comparative Example 1 as “◎”, 1.2 times or more and less than 1.4 times as “◯”, 1.0 times more than 1 Less than 2 times was evaluated as “Δ”, and 1.0 times or less was evaluated as “x”.

(Solder layer joint rate)
An air-bath type was applied, and a cooling cycle of low temperature side −45 ° C. × 30 minutes and high temperature side 175 ° C. × 30 minutes was loaded, and the joining rate after 1000 cycles was measured.
The bonding rate between the circuit layer (element mounting region) and the semiconductor element was determined using the following formula using an ultrasonic flaw detector (FineSAT 200 manufactured by Hitachi Power Solutions Co., Ltd.). Here, the initial bonding area is the area to be bonded before bonding, that is, the area of the bonding surface of the semiconductor element. In the ultrasonic flaw detection image, peeling is indicated by a white portion in the joint, and thus the area of the white portion was taken as the peeling area.
(Bonding rate) = {(initial bonding area) − (peeling area)} / (initial bonding area)

  In Comparative Example 1 in which the element mounting region and the ultrasonic bonding region were made of oxygen-free copper and the thickness was 0.2 mm, the bonding strength with the copper terminal was insufficient. This is presumably because the copper layer was deformed during ultrasonic bonding, and peeling occurred at the bonding interface between the copper layer (ultrasonic bonding region) and the aluminum layer.

  In Comparative Example 2 in which the element mounting region and the ultrasonic bonding region were made of oxygen-free copper and the thickness was 0.7 mm, the solder bonding rate after the thermal cycle load was reduced. It is presumed that the thermal expansion coefficients of the copper layer (element mounting region) and the semiconductor element are greatly different, and a high thermal stress is applied to the solder layer.

  In Comparative Example 3 in which the element mounting region and the ultrasonic bonding region were made of a copper alloy containing Zr and the thickness was 0.4 mm, the solder bonding rate after the thermal cycle load was reduced. It is presumed that the thermal expansion coefficients of the copper layer (element mounting region) and the semiconductor element are greatly different, and a high thermal stress is applied to the solder layer.

  On the other hand, the product t1 × H1 of the copper layer thickness t1 and the hardness H1 in the element mounting region, and the product t2 × H2 of the copper layer thickness t2 and the hardness H2 in the ultrasonic bonding region, In Invention Examples 1 to 9 configured to be different from each other, the bonding strength with the ultrasonically bonded copper terminal was excellent, and the bonding property with the semiconductor element solder-bonded to the element mounting region was excellent.

  In addition, Examples 1 and 2 of the present invention, which is the structure “1” in which the first copper layer and the second copper layer are formed in parallel on the aluminum layer, the first copper using a deformed copper plate having locally different thicknesses Examples 3 to 5 of the present invention having a structure “2” in which a layer and a second copper layer are formed, the first copper layer having a single-layer structure, and the second copper layer having a structure “3” having a two-layer structure It was confirmed that the same effects can be obtained with any of the structures of Examples 6 to 9.

  In addition, even when the second copper layer corresponding to the ultrasonic bonding region is made of oxygen-free copper, or made of a Cu-0.1 mass% Zr alloy, or made of a Cu-0.1 mass% Fe alloy. Even so, it was confirmed that the above-described effects can be obtained if the product t2 × H2 of the thickness t2 and the hardness H2 of the second copper layer in the ultrasonic bonding region satisfies the above-described relationship.

  As a result of the above confirmation experiment, according to the example of the present invention, in a circuit layer formed by solid phase diffusion bonding of an aluminum layer made of aluminum or an aluminum alloy and a copper layer made of copper or a copper alloy, the bondability to a semiconductor element It was confirmed that it is possible to provide an insulated circuit board that is excellent in resistance and can suppress peeling at the bonding interface between the aluminum layer and the copper layer during ultrasonic bonding.

10 Insulated circuit board 11 Ceramic board

Claims (5)

An insulating circuit board comprising an insulating layer and a circuit layer formed on one surface of the insulating layer,
The circuit layer has an aluminum layer made of aluminum or an aluminum alloy, and a copper layer made of copper or a copper alloy bonded to the aluminum layer,
On the surface of the circuit layer facing away from the insulating layer, an element mounting region on which a semiconductor element is mounted and an ultrasonic bonding region in which other members are ultrasonically bonded are formed,
The product t1 × H1 of the copper layer thickness t1 and hardness H1 in the element mounting region and the product t2 × H2 of the copper layer thickness t2 and hardness H2 in the ultrasonic bonding region are different from each other. Insulated circuit board.   The product t2 × H2 of the copper layer thickness t2 and hardness H2 in the ultrasonic bonding region is larger than the product t1 × H1 of the copper layer thickness t1 and hardness H1 in the element mounting region. The insulated circuit board according to claim 1, wherein:   The insulation according to claim 1 or 2, wherein a product t2 x H2 of the thickness t2 and the hardness H2 of the copper layer in the ultrasonic bonding region is in a range of 10 or more and 110 or less. Circuit board.   The thickness t1 of the copper layer in the element mounting region and the thickness t2 of the copper layer in the ultrasonic bonding region are different from each other. The insulated circuit board as described.   The hardness H1 of the copper layer in the element mounting region and the hardness H2 of the copper layer in the ultrasonic bonding region are different from each other. The insulated circuit board as described.

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