阅读说明：本技术 铜-钛-铝接合体、绝缘电路基板、带散热器的绝缘电路基板、功率模块、led模块、热电模块 (Copper-titanium-aluminum junction body, insulating circuit board with heat sink, power module, LED module, and thermoelectric module ) 是由 寺崎伸幸 于 2018-02-13 设计创作，主要内容包括：在本发明的铜-钛-铝接合体中,由铜或铜合金构成的铜部件和由铝或铝合金构成的铝部件经由钛层而被接合,在铜部件与钛层的接合界面形成有含有Cu和Ti的金属间化合物,在铜部件与钛层的接合界面,沿着未形成有金属间化合物的金属间化合物未形成部的接合界面的长度L<Sub>i</Sub>的最大值为20μm以下,沿着金属间化合物未形成部的接合界面的总长度ΣL<Sub>i</Sub>与所述接合界面的整体长度L<Sub>0</Sub>之比ΣL<Sub>i</Sub>/L<Sub>0</Sub>为0.16以下。(In the copper-titanium-aluminum joined body of the present invention, a copper member made of copper or a copper alloy and an aluminum member made of aluminum or an aluminum alloy are joined via a titanium layer, an intermetallic compound containing Cu and Ti is formed at a joining interface between the copper member and the titanium layer, and a length L of the joining interface along a joining interface where an intermetallic compound non-formation portion where no intermetallic compound is formed at the joining interface between the copper member and the titanium layer i Has a maximum value of 20 [ mu ] m or less, and a total length Σ L along the bonding interface of the intermetallic compound non-formed portion i The overall length L of the joint interface 0 Ratio of Σ L i /L 0 Is 0.16 or less.)

1. A copper-titanium-aluminum joined body obtained by joining a copper member made of copper or a copper alloy and an aluminum member made of aluminum or an aluminum alloy via a titanium layer, wherein the copper-titanium-aluminum joined body is characterized in that,

an intermetallic compound containing Cu and Ti is formed at the bonding interface between the copper member and the titanium layer,

a junction interface between the copper member and the titanium layer along a junction interface where an intermetallic compound non-formation portion of the intermetallic compound is not formedThe maximum value of the length Li of the surface is 20 [ mu ] m or less, and the total length Sigma Li along the bonding interface of the intermetallic compound non-formed portion and the entire length L of the bonding interface₀Ratio of Σ L_i/L₀Is 0.16 or less.

2. An insulated circuit board comprising a ceramic substrate and a circuit layer formed on one surface of the ceramic substrate, wherein the insulated circuit board is characterized in that,

the circuit layer is the copper-titanium-aluminum junction body according to claim 1.

3. An insulated circuit board comprising a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, and a metal layer formed on the other surface of the ceramic substrate,

the metal layer is the copper-titanium-aluminum junction body according to claim 1.

4. An insulated circuit board comprising a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, and a metal layer formed on the other surface of the ceramic substrate,

the circuit layer and the metal layer are the copper-titanium-aluminum junction body according to claim 1.

5. An insulated circuit board with a heat sink, comprising a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, a metal layer formed on the other surface of the ceramic substrate, and a heat sink bonded to the metal layer, wherein the insulated circuit board with a heat sink is characterized in that,

the metal layer and the heat sink are the copper-titanium-aluminum junction body according to claim 1.

6. A power module comprising the insulating circuit board according to any one of claims 2 to 4 and a power semiconductor element bonded to one surface side of the circuit layer.

7. A power module comprising the insulated circuit board with a heat sink according to claim 5 and a power semiconductor element bonded to one surface side of the circuit layer.

8. An LED module comprising the insulating circuit board according to any one of claims 2 to 4 and an LED element bonded to one surface side of the circuit layer.

9. An LED module comprising the insulated circuit board with a heat sink according to claim 5 and an LED element bonded to one surface side of the circuit layer.

10. A thermoelectric module comprising the insulating circuit board according to any one of claims 2 to 4 and a thermoelectric element bonded to one surface side of the circuit layer.

11. A thermoelectric module comprising the insulated circuit board with a heat sink according to claim 5 and a thermoelectric element bonded to one surface side of the circuit layer.

Technical Field

The present invention relates to a copper-titanium-aluminum junction body in which a copper member made of copper or a copper alloy and an aluminum member made of aluminum or an aluminum alloy are joined together via a titanium layer, and an insulated circuit board, a heat sink-equipped insulated circuit board, a power module, an LED module, and a thermoelectric module each including the copper-titanium-aluminum junction body.

Background

In the power module, the LED module, and the thermoelectric module, the power semiconductor element, the LED element, and the thermoelectric element are bonded to an insulating circuit board having a circuit layer made of a conductive material formed on one surface of an insulating layer.

For example, a power semiconductor device for high power control used for controlling wind power generation, electric vehicles, hybrid vehicles, and the like generates a large amount of heat during operation, and therefore, silicon nitride (Si) having excellent heat resistance and insulation properties is widely used as a substrate on which the power semiconductor device is mounted₃N₄) Thereby forming a ceramic substrate (insulating layer).

Further, the insulating circuit board may have a structure including: a metal plate having excellent conductivity is bonded to one surface of a ceramic substrate (insulating layer) to form a circuit layer, and a metal layer having excellent heat dissipation is bonded to the other surface to integrate them.

In this connection, studies have been made on using a joined body in which an aluminum layer and a copper layer are laminated as a circuit layer and a metal layer of an insulated circuit board (a power module board). For example, patent document 1 proposes the following: the circuit layer and the metal layer are joined to each other through a titanium layer.

In the power module, the LED module, and the thermoelectric module, an insulating circuit board with a heat sink in which a heat sink is joined to a metal layer side of the insulating circuit board is also used in order to efficiently dissipate heat generated from a semiconductor element or the like mounted on a circuit layer.

For example, patent document 1 proposes an insulated circuit board with a heat sink in which a metal layer is made of aluminum or an aluminum alloy, the heat sink is made of copper or a copper alloy, and the metal layer and the heat sink are joined to each other via a titanium layer.

In the above-described insulated circuit board and the insulated circuit board with a heat sink, the bonding state of the ceramic substrate and each of the bonding interfaces of the aluminum layer, the aluminum layer and the titanium layer, and the titanium layer and the copper layer is evaluated by ultrasonic inspection or the like.

Patent document 1: japanese patent No. 5725061

Recently, in power semiconductor elements, LED elements, thermoelectric elements, and the like mounted on an insulating circuit board, the heat generation density tends to increase, and reliability of a cooling-heating cycle up to a higher temperature than before is required for the insulating circuit board.

Here, as described above, in the insulated circuit board having a structure in which the aluminum layer and the copper layer are bonded to each other via the titanium layer and the insulated circuit board with a heat sink, peeling may occur at the bonding interface between the copper layer and the titanium layer when a cooling and heating cycle is performed at a higher temperature than in the conventional case.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a copper-titanium-aluminum joined body which can suppress occurrence of peeling at a joining interface between a copper member and a titanium layer even when a cooling-heating cycle at a higher temperature than in the related art is applied, and which is particularly excellent in reliability, and an insulated circuit board, a heat sink-equipped insulated circuit board, a power module, an LED module, and a thermoelectric module which are provided with the copper-titanium-aluminum joined body.

As a result of intensive studies to solve the above problems, the present inventors have found that: an intermetallic compound of copper and titanium is formed at the joint interface between the copper layer and the titanium layer, but a region where the intermetallic compound is not formed (intermetallic compound-free portion) is present in a part of the joint interface, and peeling occurs at the intermetallic compound-free portion in the case of a heat cycle carried to a higher temperature than in the related art. In addition, the intermetallic compound-free portion cannot be detected by ultrasonic inspection before the load of the cooling-heating cycle.

The present invention has been made in view of the above-mentioned circumstances, and an aspect of the present invention is a copper-titanium-aluminum joined body obtained by joining a copper member made of copper or a copper alloy and an aluminum member made of aluminum or an aluminum alloy via a titanium layer, wherein an intermetallic compound containing Cu and Ti is formed at a joining interface between the copper member and the titanium layer, and a length L of the joining interface along a joining interface where an intermetallic compound non-formation portion of the intermetallic compound is not formed is formed at the joining interface between the copper member and the titanium layer_iIs 20 μm or less, and a total length Σ L along a bonding interface of the intermetallic compound non-formed portion_iThe overall length L of the joint interface₀Ratio of Σ L_i/L₀Is 0.16 or less.

According to the copper-titanium-aluminum joined body having such a configuration, at the joining interface between the copper member and the titanium layer, the length L along the joining interface where the intermetallic compound non-formation portion of the intermetallic compound is not formed is determined_iHas a maximum value of 20 μm or less, the intermetallic compound is formed by sufficient diffusion of Cu and Ti between the copper member and the titanium layer, and the reliability of the junction between the copper member and the titanium layer is excellent.

And, since the total length Σ L along the bonding interface of the intermetallic compound non-formed portion_iThe overall length L of the joint interface₀Ratio of Σ L_i/L₀Since the ratio of the presence of the region in which the intermetallic compound containing Cu and Ti is not formed is 0.16 or less, the occurrence of peeling from the intermetallic compound non-formed portion as a starting point can be suppressed even in the case of a cooling-heating cycle in which a load is applied to a higher temperature than in the conventional case.

An insulated circuit board according to an aspect of the present invention includes a ceramic substrate and a circuit layer formed on one surface of the ceramic substrate, and the circuit layer is the copper-titanium-aluminum junction body described above.

According to the insulated circuit board having such a configuration, since the circuit layer is formed of the copper-titanium-aluminum junction body, even when an element having a high heat generation density is mounted on the circuit layer, peeling at the junction interface between the copper member and the titanium layer can be suppressed, and the insulated circuit board has excellent reliability.

An insulated circuit board according to an aspect of the present invention includes a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, and a metal layer formed on the other surface of the ceramic substrate, and the metal layer is the copper-titanium-aluminum junction body described above.

According to the insulated circuit board having such a configuration, since the metal layer is formed of the copper-titanium-aluminum junction body, the junction reliability between the copper member and the titanium layer is excellent, and heat from the element mounted on the circuit layer can be efficiently dissipated via the metal layer.

An insulated circuit board according to an aspect of the present invention includes a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, and a metal layer formed on the other surface of the ceramic substrate, and the circuit layer and the metal layer are the copper-titanium-aluminum junction body described above.

According to the insulated circuit board having such a configuration, since the circuit layer and the metal layer are formed of the copper-titanium-aluminum junction body, even when an element having a high heat generation density is mounted on the circuit layer, peeling at the junction interface between the copper member and the titanium layer can be suppressed, and the insulated circuit board has excellent reliability. Further, heat from the element mounted on the circuit layer can be efficiently dissipated via the metal layer.

An insulated circuit board with a heat sink according to an aspect of the present invention is an insulated circuit board with a heat sink comprising a ceramic substrate, a circuit layer formed on one surface of the ceramic substrate, a metal layer formed on the other surface of the ceramic substrate, and a heat sink bonded to the metal layer, wherein the metal layer and the heat sink are the copper-titanium-aluminum junction body described above.

According to the insulated circuit board with a heat sink having such a configuration, since the metal layer and the heat sink are made of the copper-titanium-aluminum bonded body, even under a high load, peeling is suppressed from occurring at the bonding interface between the copper member and the titanium layer formed between the metal layer and the heat sink, and the insulated circuit board with a heat sink is excellent in reliability.

A power module according to an aspect of the present invention includes the insulating circuit board described above and a power semiconductor element bonded to one surface side of the circuit layer.

A power module according to an aspect of the present invention includes the insulated circuit board with a heat sink described above and a power semiconductor element bonded to one surface side of the circuit layer.

An LED module according to an aspect of the present invention includes the insulating circuit board described above and an LED element bonded to one surface side of the circuit layer.

An LED module according to an aspect of the present invention includes the insulated circuit board with a heat sink described above and an LED element bonded to one surface side of the circuit layer.

A thermoelectric module according to an aspect of the present invention includes the insulating circuit board described above and a thermoelectric element bonded to one surface side of the circuit layer.

A thermoelectric module according to an aspect of the present invention includes the insulated circuit board with a heat sink described above and a thermoelectric element bonded to one surface side of the circuit layer.

According to the power module, the LED module, and the thermoelectric module of one aspect of the present invention, the copper-titanium-aluminum joined body can suppress occurrence of peeling at the joining interface between the copper member and the titanium layer even under a high load, and can improve the reliability of the power module, the LED module, and the thermoelectric module.

According to the present invention, it is possible to provide a copper-titanium-aluminum junction body which can suppress occurrence of peeling at a junction interface between a copper member and a titanium layer even when a cooling-heating cycle at a temperature higher than that of a conventional one is carried, and which is particularly excellent in reliability, and an insulated circuit board, a heat sink-equipped insulated circuit board, a power module, an LED module, and a thermoelectric module which are provided with the copper-titanium-aluminum junction body.

Drawings

Fig. 1 is a cross-sectional view showing a copper-titanium-aluminum junction body, an insulated circuit board, and a power module according to a first embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view of a main portion of the copper-titanium-aluminum junction body (circuit layer and metal layer) shown in fig. 1, the main portion being in the vicinity of a junction interface.

Fig. 3 is a flowchart showing a method of manufacturing the insulated circuit board and the power module shown in fig. 1.

Fig. 4 is an explanatory view showing a method of manufacturing the insulated circuit board shown in fig. 1.

Fig. 5 is a cross-sectional view showing a copper-titanium-aluminum junction body, a heat sink-equipped insulated circuit board, and a power module according to a second embodiment of the present invention.

Fig. 6 is an enlarged cross-sectional view of a principal part showing the vicinity of the junction interface of the copper-titanium-aluminum junction body (metal layer and heat sink) shown in fig. 5.

Fig. 7 is a flowchart showing a method for manufacturing the insulated circuit board with a heat sink and the power module shown in fig. 5.

Fig. 8 is an explanatory view showing a method of manufacturing the insulated circuit board with a heat sink shown in fig. 5.

Fig. 9 is a cross-sectional view showing a copper-titanium-aluminum junction body, an insulated circuit board, and a power module according to another embodiment of the present invention.

Fig. 10 is a cross-sectional view showing a copper-titanium-aluminum junction body, an insulated circuit board, and a power module according to another embodiment of the present invention.

Fig. 11 is an explanatory view of a pressing jig used in a comparative example.

FIG. 12 is a composition image of a cross section of a bonding interface in the copper-titanium-aluminum bonded body of example 1 of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the present invention will be described specifically for better understanding of the gist of the present invention, and the present invention is not limited to these embodiments unless otherwise specified. In the drawings used in the following description, for the sake of easy understanding of the features of the present invention, parts that become essential parts may be enlarged for convenience, and the dimensional ratios of the respective constituent elements and the like are not limited to those in practice.

(first embodiment)

Fig. 1 shows a power module 1 using an insulated circuit board 10 according to a first embodiment of the present invention. In addition, the joint body in the present embodiment is provided in the insulating circuit board 10 shown in fig. 1: a circuit layer 20 formed by joining an aluminum layer 21 as an aluminum member and a copper layer 22 as a copper member via a titanium layer 25; and a metal layer 30 formed by joining an aluminum layer 31 as an aluminum member and a copper layer 32 as a copper member via a titanium layer 35.

The power module 1 shown in fig. 1 includes: an insulated circuit board (10); a power semiconductor element 3 bonded to one surface (upper surface in fig. 1) of the insulating circuit board 10 via a first solder layer 2; and a heat sink 41 joined to the lower side of the insulated circuit board 10 via a second solder layer 42. The insulated circuit board 10 to which the heat sink 41 is joined is the insulated circuit board with a heat sink 40 in the present embodiment.

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

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

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

The ceramic substrate 11 is made of AlN (aluminum nitride) or Si having high insulation₃N₄(nitridingSilicon), Al₂O₃(alumina), and the like. In the present embodiment, Si having excellent strength is used₃N₄(silicon nitride). The thickness of the ceramic substrate 11 is set to be in the range of 0.2 to 1.5mm, and in the present embodiment, 0.32 mm.

As shown in fig. 1, the circuit layer 20 has: an aluminum layer 21 disposed on one surface of the ceramic substrate 11; and a copper layer 22 laminated on one surface of the aluminum layer 21 through a titanium layer 25.

Here, the thickness of the aluminum layer 21 in the circuit layer 20 is set to be in the range of 0.1mm to 1.0mm, and in the present embodiment, 0.4 mm.

The thickness of the copper layer 22 in the circuit layer 20 is set to be in the range of 0.1mm to 6.0mm, and is set to be 1.0mm in the present embodiment.

As shown in fig. 1, the metal layer 30 has: 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 via a titanium layer 35.

Here, the thickness of the aluminum layer 31 in the metal layer 30 is set to be in the range of 0.1mm to 3.0mm, and in the present embodiment, 0.4 mm.

The thickness of the copper layer 32 in the metal layer 30 is set to be in the range of 0.1mm to 6.0mm, and is set to be 1.0mm in the present embodiment.

Here, as shown in fig. 4, the aluminum layers 21 and 31 are formed by bonding aluminum plates 51 and 61 to one surface and the other surface of the ceramic substrate 11.

The aluminum plates 51, 61 to be the aluminum layers 21, 31 are composed of aluminum (2N aluminum) having a purity of 99 mass% or more. That is, the content of Si is set in the range of 0.03 mass% to 1.0 mass%.

The copper layers 22 and 32 are formed by bonding copper plates 52 and 62 made of copper or a copper alloy to one surface and the other surface of the aluminum layers 21 and 31 via titanium layers 25 and 35. In the present embodiment, the copper plates 52, 62 constituting the copper layers 22, 32 are rolled plates of oxygen-free copper.

The aluminum layers 21 and 31 and the titanium layers 25 and 35, and the titanium layers 25 and 35 and the copper layers 22 and 32 are solid-phase diffusion bonded to each other.

Here, as shown in fig. 2, Al — Ti — Si layers 26 and 36 are formed at the bonding interfaces between the aluminum layers 21 and 31 and the titanium layers 25 and 35.

The Al-Ti-Si layers 26, 36 are solid-dissolved in Al by Si of the aluminum layers 21, 31₃Formed in Ti, the Al₃Ti is formed by Al atoms of the aluminum layers 21, 31 and Ti atoms of the titanium layers 25, 35 diffusing into each other.

The thickness of the Al-Ti-Si layers 26, 36 is set to 0.5 μm or more and 10 μm or less, and 3 μm in the present embodiment.

As shown in fig. 2, intermetallic compound phases 27 and 37 containing Ti and Cu are formed at the junction interfaces between the titanium layers 25 and 35 and the copper layers 22 and 32.

The intermetallic compound phases 27 and 37 are formed by diffusion of Cu atoms of the copper layers 22 and 32 and Ti atoms of the titanium layers 25 and 35.

As shown in fig. 2, regions (intermetallic compound non-formed portions 28 and 38) where the intermetallic compound phases 27 and 37 are not formed are present at the junction interfaces between the titanium layers 25 and 35 and the copper layers 22 and 32.

Here, in the present embodiment, the length L along the joint interface of the intermetallic compound non-formed portion 28, 38 is set to be longer_iThe maximum value of (2) is 20 μm or less.

And, the total length Σ L along the bonding interface of the intermetallic compound non-formed portions 28, 38_iOverall length L of interface with joint₀Ratio of Σ L_i/L₀Is 0.16 or less.

In the present embodiment, as a result of observing the bonding interface between the titanium layers 25 and 35 and the copper layers 22 and 32, the length L of the bonding interface between the intermetallic compound non-formed portions 28 and 38 is observed_iIs set to 20 μm or less, and the total length Σ L along the bonding interface of the intermetallic compound non-formed portions 28, 38 observed_iOverall length L of interface with joint in viewing field₀Ratio of Σ L_i/L₀Is 0.16 or less.

When the junction interface between the titanium layers 25, 35 and the copper layers 22, 32 is observed, the cross-sectional view of the insulated circuit board 10 is observed by EPMA,obtaining elemental MAP of Cu and Ti in a region including a bonding interface between the titanium layers 25, 35 and the copper layers 22, 32 (longitudinal length 100 μm × horizontal length 200 μm), wherein a region having a Cu concentration of 5 atomic% or more and a Ti concentration of 16 atomic% or more and 70 atomic% or less is defined as an intermetallic compound phase 27, 37, and a region between the intermetallic compound phases 27, 37 in the bonding interface is defined as a length L along the bonding interface between the intermetallic compound non-formed portions 28, 38_i. The measurement was carried out in 10 visual fields, and the length L along the joint interface between the intermetallic compound non-formed portions 28 and 38 was calculated_iAnd the total length Σ L along the observed bonding interface of the intermetallic compound non-formed portions 28, 38_iOverall length L of interface with joint in viewing field₀Ratio of Σ L_i/L₀。

Next, a method for manufacturing the insulated circuit board 10 according to the present embodiment will be described with reference to fig. 3 and 4.

First, as shown in fig. 4, an aluminum plate 51 to be an aluminum layer 21 is laminated on one surface (upper surface in fig. 4) of the ceramic substrate 11, and further, a copper plate 52 to be a copper layer 22 is laminated thereon via a titanium material 55. An aluminum plate 61 to be an aluminum layer 31 is laminated on the other surface (lower surface in fig. 4) of the ceramic substrate 11, and a copper plate 62 to be a copper layer 32 is further laminated thereon via a titanium material 65. In the present embodiment, aluminum plates 51 and 61 are laminated on ceramic substrate 11 via Al — Si-based brazing filler metal foils 58 and 68. (laminating step S01)

Then, under vacuum conditions, in the lamination direction, at 8kgf/cm²Above and 20kgf/cm²Aluminum plate 51 and ceramic substrate 11 were joined by heating under pressure in the following range, and further aluminum plate 51 and titanium material 55, titanium material 55 and copper plate 52 were solid-phase diffused to form circuit layer 20. Then, the aluminum plate 61 and the ceramic substrate 11 are joined, and further, the aluminum plate 61 and the titanium material 65, the titanium material 65 and the copper plate 62 are solid-phase diffused, thereby forming the metal layer 30. (Circuit layer and Metal layer Forming Process S02)

Here, in the present embodiment, the vacuum condition is set to 10^-6Pa is 10 or more^-3Pa or lessThe heating temperature is set to 630 ℃ to 643 ℃ and the holding time is set to 210 minutes to 360 minutes.

In the present embodiment, the pressing and heating are performed using a hot press apparatus so that the pressing pressure is within the above range at the bonding temperature.

The surfaces of the aluminum plates 51 and 61, the titanium materials 55 and 65, and the copper plates 52 and 62, which are bonded to each other, are subjected to solid-phase diffusion bonding after the scratches on the surfaces are removed and smoothed in advance.

The insulated circuit board 10 of the present embodiment is manufactured as described above.

Next, the heat sink 41 is laminated on the metal layer 30 of the insulated circuit board 10 via the solder material, and solder bonding is performed in a reducing furnace (heat sink bonding step S03).

The insulated circuit board with a heat sink 40 of the present embodiment is manufactured in this manner.

Next, the power semiconductor elements 3 are laminated on one surface (surface of the copper layer 22) of the circuit layer 20 via a solder material, and solder bonding is performed in a reducing furnace (power semiconductor element bonding step S04).

The power module 1 of the present embodiment is manufactured as described above.

In the insulated circuit board 10 of the present embodiment configured as described above, the circuit layer 20 has a structure in which the aluminum layer 21, the titanium layer 25, and the copper layer 22 are solid-phase diffused, respectively, and the metal layer 30 has a structure in which the aluminum layer 31, the titanium layer 35, and the copper layer 32 are solid-phase diffusion bonded, respectively, and therefore, at the bonding interface between the copper layer 22, 32 and the titanium layer 25, 35, the length L along the bonding interface where the intermetallic compound non-formation portions 28, 38 of the intermetallic compound phases 27, 37 containing Cu and Ti are not formed is formed_iIs set to 20 μm or less, Cu and Ti are sufficiently diffused into each other between the copper layers 22, 32 and the titanium layers 25, 35, and the bonding reliability of the copper layers 22, 32 and the titanium layers 25, 35 is excellent.

In addition, the total length Σ L of the bonding interface between the copper layers 22, 32 and the titanium layers 25, 35 along the bonding interface between the intermetallic compound non-formed portions 28, 38_iOverall length L of interface with joint₀Ratio of Σ L_i/L₀Since the ratio of the intermetallic compound non-formed portions 28 and 38 is set to 0.16 or less, the occurrence of peeling from the intermetallic compound non-formed portions 28 and 38 can be suppressed even in a cooling and heating cycle in which a load is applied to a high temperature.

As described above, since the copper layer 22 and the titanium layer 25 in the circuit layer 20 have excellent bonding reliability, even when the power semiconductor element 3 having high heat generation density is mounted on the circuit layer 20, peeling at the bonding interface between the copper layer 22 and the titanium layer 25 can be suppressed.

Further, since the copper layer 32 and the titanium layer 35 in the metal layer 30 have excellent bonding reliability, heat from the power semiconductor element 3 mounted on the circuit layer 20 can be efficiently dissipated to the heat sink 41 side via the metal layer 30.

In addition, in the present embodiment, since the aluminum layers 21 and 31 having small deformation resistance are formed on the one surface and the other surface of the ceramic substrate 11, thermal stress generated when a heating/cooling cycle is applied can be absorbed by deformation of the aluminum layers 21 and 31, and generation of cracks in the ceramic substrate 11 can be suppressed.

Further, since the copper layers 22 and 32 having a large deformation resistance are formed on the surfaces of the aluminum layers 21 and 31 opposite to the surface on which the ceramic substrate 11 is formed, deformation of the surfaces of the circuit layer 20 and the metal layer 30 is suppressed during a cold/hot cycle, and cracks can be suppressed from being generated in the first solder layer 2 for bonding the circuit layer 20 and the power semiconductor element 3 and the second solder layer 42 for bonding the metal layer 30 and the heat sink 41, thereby improving bonding reliability.

In addition, in the present embodiment, since the ceramic substrate 11, the aluminum plates 51 and 61, the titanium materials 55 and 65, and the copper plates 52 and 62 are joined at once, the manufacturing process can be simplified, and the manufacturing cost can be reduced.

In the present embodiment, the configuration is such that: the aluminum plates 51, 61, the titanium materials 55, 65, and the copper plates 52, 62 are solid-phase diffusion bonded by applying 8 to 20kgf/cm in the lamination direction²Is maintained at 630 to 643 ℃ inclusive, and thus the Al source is made to beThe atoms and Ti atoms, and the atoms and Cu atoms are diffused into each other, and Al and Cu atoms are solid-phase diffused into the titanium material 25 to be solid-phase diffusion bonded, so that the aluminum plates 51 and 61, the titanium materials 55 and 65, and the copper plates 52 and 62 can be reliably bonded.

In addition, in the present embodiment, since the hot press apparatus is used so that the pressing pressure in the stacking direction at the heating temperature (bonding temperature) is within the above range, the diffusion of Ti atoms and Cu atoms between the titanium layers 25 and 35 and the copper layers 22 and 32 can be sufficiently promoted, and the length L along the bonding interface of the intermetallic compound non-formed portions 28 and 38 can be made to be along the length L_iOverall length L of interface with joint₀Ratio of Σ L_i/L₀Within the above range.

(second embodiment)

Fig. 5 shows a power module 101 using an insulating circuit board with a heat sink 140 according to a second embodiment of the present invention. The same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the joined body of the present embodiment, the metal layer 130 as an aluminum member and the heat sink 141 as a copper member are joined to each other via the titanium layer 145 in the heat sink-equipped insulating circuit board 140 shown in fig. 5.

The power module 101 shown in fig. 5 includes: an insulating circuit board with a heat sink 140; and a power semiconductor element 3 bonded to one surface (upper surface in fig. 5) of the heat sink mounted insulating circuit board 140 via the first solder layer 2. The insulated circuit board with a heat sink 140 of the present embodiment includes: an insulating circuit substrate 110; and a heat sink 141 bonded to the metal layer 130 of the insulating circuit board 110.

The heat sink 141 is for dissipating heat on the insulating circuit substrate 110 side. The heat sink 141 is made of copper or a copper alloy, and in the present embodiment, oxygen-free copper.

As shown in fig. 5, the insulated circuit board 110 includes a ceramic substrate 11, a circuit layer 120 disposed on one surface (upper surface in fig. 5) of the ceramic substrate 11, and a metal layer 130 disposed on the other surface (lower surface in fig. 5) of the ceramic substrate 11.

As shown in fig. 8, the circuit layer 120 is formed by bonding an aluminum plate 151 made of aluminum or an aluminum alloy to one surface (upper surface in fig. 8) of the ceramic substrate 11. In the present embodiment, the circuit layer 120 is formed by bonding a rolled sheet of aluminum (2N aluminum) having a purity of 99% or more to the ceramic substrate 11. The thickness of aluminum plate 151 to be circuit layer 120 is set to be in the range of 0.1mm to 1.0mm, and in the present embodiment, 0.6 mm.

As shown in fig. 8, the metal layer 130 is formed by bonding an aluminum plate 161 to the other surface (lower surface in fig. 8) of the ceramic substrate 11. In the present embodiment, the aluminum plate 161 constituting the metal layer 130 is a rolled plate of aluminum (4N aluminum) having a purity of 99.99 mass% or more. The thickness of the aluminum plate 161 to be joined is set to be in the range of 0.1mm to 3.0mm, and is set to be 0.6mm in the present embodiment.

In the insulated circuit board with a heat sink 140 of the present embodiment, as shown in fig. 5, the metal layer 130 and the heat sink 141 are bonded to each other through the titanium layer 145.

In addition, metal layer 130 and titanium layer 145, titanium layer 145 and heat spreader 141 are solid-phase diffusion bonded, respectively.

As shown in fig. 6, Al — Ti — Si layer 146 is formed at the junction interface between metal layer 130 and titanium layer 145.

The Al-Ti-Si layer 146 is formed by solid-dissolving Si in Al of the metal layer 130₃Formed in Ti, the Al₃Ti is formed by Al atoms of the metal layer 130 and Ti atoms of the titanium layer 145 diffusing into each other.

The thickness of the Al-Ti-Si layer 146 is set to 0.5 μm or more and 10 μm or less, and 3 μm in the present embodiment.

As shown in fig. 6, an intermetallic compound phase 147 containing Ti and Cu is formed at the bonding interface between titanium layer 145 and heat spreader 141.

This intermetallic compound phase 147 is formed by diffusion of Cu atoms of the heat spreader 141 and Ti atoms of the titanium layer 145 into each other.

As shown in fig. 2, there may be a region where intermetallic compound phase 147 is not formed (intermetallic compound non-formed portion 148) at the bonding interface between titanium layer 145 and heat spreader 141.

Here, in the present embodiment, the length L along the bonding interface of the intermetallic compound non-formed portion 148 is set to be longer than the length L of the intermetallic compound non-formed portion_iThe maximum value of (2) is 20 μm or less.

And, the total length Σ L along the bonding interface of the intermetallic compound non-formed portion 148_iOverall length L of interface with joint in viewing field₀Ratio of Σ L_i/L₀Is set to 0.16 or less.

The observation of the junction interface between titanium layer 145 and heat spreader 141 was performed under the same conditions as in the first embodiment.

Next, a method for manufacturing the insulated circuit board with a heat sink 140 according to the present embodiment will be described with reference to fig. 7 and 8.

First, as shown in fig. 8, aluminum plate 151 to be circuit layer 120 is laminated on one surface (upper surface in fig. 8) of ceramic substrate 11, and aluminum plate 161 to be metal layer 130 is laminated on the other surface (lower surface in fig. 8) of ceramic substrate 11. Then, heat sink 141 is laminated on the other surface side of aluminum plate 161 serving as metal layer 130 via titanium material 165 (laminating step S101).

In the present embodiment, aluminum plates 151 and 161 and ceramic substrate 11 are laminated via Al — Si-based brazing filler metal foils 58 and 68.

Then, under vacuum conditions, the thickness was 8kgf/cm in the lamination direction²Above and 20kgf/cm²Heating was performed in a pressurized state in the following range to bond aluminum plate 151 and ceramic substrate 11, and circuit layer 120 was formed. Aluminum plate 161 and ceramic substrate 11 are then joined together to form metal layer 130 (circuit layer and metal layer forming step S102).

At the same time, aluminum plate 161 and titanium material 165, and titanium material 165 and heat sink 141 are solid-phase diffusion bonded (heat sink bonding step S103).

Here, in the present embodiment, the vacuum condition is set to 10^-6Pa is 10 or more^-3Pa or less, a heating temperature of 630-643 deg.C, and a holding time of 210 min or moreAnd less than 360 minutes.

In the present embodiment, the pressing and heating are performed using a hot press apparatus so that the pressing pressure is within the above range at the bonding temperature.

The bonding surfaces of aluminum plate 161, titanium material 165, and heat sink 141 are subjected to solid-phase diffusion bonding after scratches on the bonding surfaces are removed and smoothed in advance.

As described above, the insulated circuit board with a heat sink 140 of the present embodiment is manufactured.

Next, the power semiconductor elements 3 are stacked on one surface of the circuit layer 120 of the insulating circuit board 110 via a solder material, and solder bonding is performed in a reducing furnace (power semiconductor element bonding step S104).

As described above, the power module 101 of the present embodiment is manufactured.

In the insulated circuit board with a heat sink 140 of the present embodiment configured as described above, the metal layer 130 and the titanium layer 145 as the aluminum component, the titanium layer 145 and the heat sink 141 as the copper component are solid-phase diffusion bonded to each other, and the length L along the bonding interface where the intermetallic compound non-formation portion 148 not having the intermetallic compound phase 147 containing Cu and Ti is formed at the bonding interface between the heat sink 141 and the titanium layer 145_iIs set to 20 μm or less, Cu and Ti sufficiently diffuse each other between heat spreader 141 and titanium layer 145, and the bonding reliability of heat spreader 141 and titanium layer 145 is excellent.

In addition, at the bonding interface between heat spreader 141 and titanium layer 145, the total length Σ L along the bonding interface of intermetallic compound non-formed portion 148_iOverall length L of interface with joint₀Ratio of Σ L_i/L₀Since the ratio of the intermetallic compound non-formed portion 148 is set to 0.16 or less, the occurrence of peeling from the intermetallic compound non-formed portion 148 as a starting point can be suppressed even in a cooling and heating cycle in which a load is applied to a high temperature.

As described above, since the metal layer 130 as the aluminum member and the heat sink 141 as the copper member are joined via the titanium layer 145, and the joining reliability between the heat sink 141 and the titanium layer 145 is excellent, even in the case of a cold/hot cycle in which a load is increased to a high temperature, it is possible to suppress the occurrence of peeling at the joining interface between the heat sink 141 and the titanium layer 145, and to efficiently radiate heat from the power semiconductor element 3 mounted on the circuit layer 120 to the heat sink 141 side via the metal layer 130.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can be modified as appropriate without departing from the technical spirit of the present invention.

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

As in the power module 201 and the insulating circuit board 210 shown in fig. 9, only the circuit layer 220 may be formed of a copper-titanium-aluminum junction body in which a copper member (copper layer 222) made of copper or a copper alloy and an aluminum member (aluminum layer 221) made of aluminum or an aluminum alloy are joined to each other via a titanium layer 225.

Alternatively, as in the power module 301 and the insulated circuit board 310 shown in fig. 10, only the metal layer 330 may be formed of a copper-titanium-aluminum junction body in which a copper member (copper layer 332) made of copper or a copper alloy and an aluminum member (aluminum layer 331) made of aluminum or an aluminum alloy are joined to each other via a titanium layer 335.

In the present embodiment, the description has been given of the case where the aluminum layer and the titanium layer are solid-phase diffusion bonded, but the present invention is not limited to this, and any copper-titanium-aluminum bonded body may be used as long as the structure is such that the titanium layer and the copper layer are solid-phase diffusion bonded and an intermetallic compound containing Cu and Ti is formed at the bonding interface between the titanium layer and the copper layer.