JP6558272B2 - Manufacturing method of joined body, manufacturing method of power module substrate with heat sink, joined body and power module substrate with heat sink - Google Patents

Description

  The present invention relates to a method for manufacturing a joined body in which a metal member made of copper or a copper alloy and a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member, and a power module substrate with a heat sink The manufacturing method, the joined body, and the substrate for a power module with a heat sink.

In general, in a power semiconductor element for high power control used for controlling wind power generation, electric vehicles, hybrid vehicles, etc., since the amount of heat generated is large, as a substrate on which such a power semiconductor element is mounted, for example, A ceramic substrate made of AlN (aluminum nitride), Al ₂ O ₃ (alumina), 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 power module substrate provided has been widely used. As circuit layers and metal layers of power module substrates, copper members such as copper and copper alloys and aluminum members such as aluminum and aluminum alloys are widely used.

In addition, in order to efficiently dissipate heat generated from a mounted semiconductor element or the like, there is provided a power module substrate with a heat sink in which a heat sink is bonded to the metal layer side of the power module substrate.
The heat sink preferably has a low coefficient of linear expansion and a high thermal conductivity. MgSiC is known as a heat sink material having such a low coefficient of linear expansion and high thermal conductivity. This MgSiC is a silicon carbide filled with magnesium or a magnesium alloy.

  Non-Patent Document 1 describes joining MgSiC and an aluminum nitride (AlN) substrate with a double-sided Al layer with solder.

Isao Iwayama, 5 others, “New heat sink for power modules for electric railway vehicles”, SEI Technical Review, No. 184, pp. 61-65, January 2014

  By the way, recently, higher output of power semiconductor elements and the like has been promoted, and a severe heat cycle has been applied to the power module substrate with a heat sink on which the power semiconductor element is mounted. There is a demand for a power module substrate with a heat sink having excellent bonding reliability with respect to the cycle. However, as described in Non-Patent Document 1, when the metal layer of the power module substrate and the heat sink are joined with solder, cracks occur in the solder during a heat cycle load, and the joining rate decreases. As a result, the thermal resistance may increase.

  Therefore, it is desirable if the power module substrate and MgSiC can be joined without using solder. However, according to the study of the present inventors, when the copper member used as the metal layer of the power module substrate and MgSiC are heated by direct contact, a large amount of Cu-Mg liquid phase is generated, and the copper member and MgSiC It has been found that it is difficult to bond the copper member and MgSiC with excellent bonding reliability. The reason why a large amount of Cu-Mg liquid phase is generated is that when Cu and Mg are in contact with each other, when heated to a temperature higher than the eutectic temperature of Cu and Mg, a Cu-Mg mixed melt is generated. Since the copper member and MgSiC to be joined each have a thickness of about several millimeters, a large amount of Cu and Mg will continue to be supplied to the joining interface where the Cu-Mg mixed melt is generated. It is thought that the Cu-Mg mixed melt leaks out from there.

  The present invention has been made in view of the above-mentioned circumstances, and is a magnesium member typified by a metal member such as copper or a copper alloy widely used as a metal layer of a power module substrate and MgSiC that can be used as a heat sink. An object of the present invention is to provide a method for manufacturing a bonded body and a method for manufacturing a substrate for a power module with a heat sink, which can be bonded to the base composite material with excellent bonding reliability without using solder. Another object of the present invention is to provide a joined body in which a metal member such as copper or copper alloy and a magnesium-based composite material are joined without using solder, and a power module substrate with a heat sink.

  In order to solve the above-described problem, a method for manufacturing a joined body according to the present invention includes a metal member made of copper or a copper alloy and a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member. A method for producing a joined body, comprising: arranging a titanium foil between the metal member and the magnesium-based composite material; solid-phase joining the metal member and the titanium foil; and The magnesium-based composite material is liquid phase bonded using a bonding material made of any of copper, nickel, silver, aluminum, and an alloy of aluminum and silicon. In addition, in this invention, copper, nickel, and silver shall include those alloys.

  According to the method of manufacturing a joined body having this configuration, since the titanium foil is disposed between the metal member and the magnesium-based composite material, the titanium foil acts as a barrier film, and the metal member and the magnesium There is no direct contact between the matrix composites. Therefore, a large amount of Cu—Mg mixed melt is suppressed. Further, since the titanium foil is disposed between the metal member and the magnesium-based composite material, the magnesium-based composite material and the titanium foil are joined, and the titanium foil and the metal member are joined. Therefore, the metal member and the magnesium-based composite material can be firmly bonded via the titanium foil. Therefore, it is possible to manufacture a bonded body having excellent bonding reliability.

  Moreover, in the manufacturing method of the joined body of this invention, it is preferable that titanium foil exists in the range of 3 micrometers or more and 85 micrometers or less. According to this configuration, since the thickness of the titanium foil is 3 μm or more, it is possible to more reliably prevent the metal member and the magnesium-based composite material from coming into direct contact. Moreover, since the thickness of the titanium foil is 85 μm or less, the titanium foil that becomes the thermal resistance can be thinned, and the thermal resistance of the joined body can be lowered. Therefore, it is possible to manufacture a bonded body having excellent bonding reliability and heat dissipation characteristics.

  Moreover, in the manufacturing method of the joined body of this invention, it is preferable that the said joining material is a joining material which consists of an alloy of aluminum and silicon. Among the alloys of copper, nickel, silver, aluminum, and aluminum and silicon that can be used as the bonding material, an alloy of aluminum and silicon generates a molten mixture with magnesium at the lowest temperature, so that the liquid phase The time that can be maintained becomes longer, and the titanium foil and the magnesium-based composite material can be firmly bonded. Therefore, it is possible to manufacture a bonded body with higher bonding reliability.

  The method for manufacturing a power module substrate with a heat sink according to the present invention includes an insulating layer, a circuit layer made of copper or a copper alloy formed on one surface of the insulating layer, and the other surface of the insulating layer. A heat sink formed by bonding a metal layer of a power module substrate including a metal layer made of copper or a copper alloy and a heat sink that is a magnesium-based composite material in which a carbonaceous member is filled with magnesium or a magnesium alloy. A power module substrate manufacturing method comprising: disposing a titanium foil between the metal layer and the magnesium-based composite material; solid-phase bonding the metal layer and the titanium foil; and Liquid phase bonding with the magnesium-based composite material using a bonding material made of copper, nickel, silver, aluminum, or an alloy of aluminum and silicon. It is a symptom.

  According to the manufacturing method of the power module substrate with a heat sink having this configuration, the titanium foil is disposed between the metal layer of the power module substrate and the magnesium-based composite material that is the heat sink. It acts as a barrier film, and the metal layer of the power module substrate and the magnesium-based composite material do not come into direct contact. Therefore, a large amount of Cu—Mg mixed melt is suppressed. Further, since the titanium foil is disposed between the metal layer of the power module substrate and the magnesium-based composite material, the magnesium-based composite material and the titanium foil are joined, and the titanium foil and the power module are joined. Since the metal layer of the power substrate is bonded, the metal layer of the power module substrate and the magnesium-based composite material can be firmly bonded via the titanium foil.

  The joined body of the present invention is a joined body in which a metal member made of copper or a copper alloy and a magnesium-based composite material in which a carbonaceous member is filled with magnesium or a magnesium alloy are joined. And the magnesium-based composite material, a titanium layer is disposed, and the metal member and the titanium layer are bonded via an intermetallic compound layer containing copper and titanium, and the titanium layer and the titanium layer The magnesium-based composite material is joined through the additive element-magnesium-containing layer including the additive element-magnesium phase, and the magnesium-based composite material in contact with the additive element-magnesium-containing layer includes the additive element. A diffusion layer is formed, and the additive element is copper, nickel, silver, aluminum, or a combination of aluminum and silicon It is.

  According to the structure of the joined body, the titanium layer and the magnesium-based composite material are joined via the additive element-magnesium-containing layer including an additive element-magnesium phase, and the additive element-magnesium-containing layer By forming a diffusion layer containing an additive element in the magnesium-based composite material that is in contact, the bonding strength between the titanium layer and the magnesium-based composite material is increased. Moreover, when the metal member and the titanium layer are bonded via an intermetallic compound layer containing copper and titanium, the bonding strength between the metal member and the titanium layer is increased. Therefore, this joined body is excellent in joining reliability between the magnesium-based composite material and the metal member.

  Here, in the joined body of the present invention, it is preferable that the titanium layer is in a range of 1 μm to 84 μm. According to this configuration, since the thickness of the titanium layer is 1 μm or more, Cu in the metal member and Mg in the magnesium-based composite material are joined via the titanium layer without being in direct contact with each other. , Bonding reliability is improved. Moreover, since the thickness of the titanium layer is 84 μm or less, the thermal resistance of the titanium layer is lowered. Therefore, it is possible to manufacture a bonded body having excellent bonding reliability and heat dissipation characteristics.

  The power module substrate with a heat sink of the present invention includes an insulating layer, a circuit layer made of copper or a copper alloy formed on one surface of the insulating layer, and copper or copper formed on the other surface of the insulating layer. A power module with a heat sink formed by joining a metal layer of a power module substrate including an alloy metal layer and a heat sink, which is a magnesium-based composite material in which a carbonaceous member is filled with magnesium or a magnesium alloy. A titanium substrate is disposed between the metal layer and the magnesium-based composite material, and the metal layer and the titanium layer are bonded via an intermetallic compound layer containing copper and titanium. The titanium layer and the magnesium-based composite material are joined via an additive element-magnesium-containing layer including an additive element-magnesium phase. A diffusion layer containing an additive element is formed in the magnesium-based composite material in contact with the additive element-magnesium-containing layer, and the additive element is a combination of copper, nickel, silver, aluminum, aluminum and silicon. It is characterized by being either.

  According to the configuration of the power module substrate with a heat sink, the titanium layer and the magnesium-based composite material that is the heat sink are bonded via an additive element-magnesium-containing layer including an additive element-magnesium phase, By forming a diffusion layer containing an additive element in the magnesium-based composite material in contact with the additive element-magnesium-containing layer, the bonding strength between the magnesium-based composite material and the titanium layer is increased. In addition, the bonding strength between the metal layer and the titanium layer is increased by bonding the metal layer of the power module substrate and the titanium layer via an intermetallic compound layer containing copper and titanium. . Therefore, the power module substrate with a heat sink has excellent bonding reliability between the heat sink and the power module substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the joined body which can join metal members, such as copper or copper alloy, and the magnesium group composite material represented by MgSiC by soldering without using solder, and with a heat sink It is possible to provide a method for manufacturing a power module substrate. Moreover, according to this invention, the board | substrate for power modules with a joining body and heat sink which joined metal members, such as copper or a copper alloy, and magnesium group composite material, without using solder can be provided. The power module substrate with a heat sink according to the present invention does not use solder in the production thereof, and therefore does not cause a decrease in bonding rate or an increase in thermal resistance due to cracks in the solder during a heat cycle load. Can be used.

It is a schematic explanatory drawing explaining the board | substrate for power modules with a heat sink which is embodiment of this invention. It is a schematic explanatory drawing explaining the manufacturing method of the board | substrate for power modules with a heat sink which is embodiment of this invention. It is a schematic explanatory drawing explaining the other manufacturing method of the board | substrate for power modules with a heat sink which is embodiment of this invention. It is a schematic explanatory drawing explaining the manufacturing method of the laminated body by which the board | substrate for power modules used for embodiment of this invention and the titanium foil 30 were solid-phase joined. It is a schematic explanatory drawing explaining the further another manufacturing method of the board | substrate for power modules with a heat sink which is embodiment of this invention.

  Hereinafter, embodiments of a power module substrate with a heat sink and a method for manufacturing the same according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory view illustrating a power module substrate with a heat sink according to an embodiment of the present invention.
The power module substrate with a heat sink of this embodiment includes a ceramic substrate 11 constituting an insulating layer, a circuit layer 12 formed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11, and the other of the ceramic substrate 11. The metal layer 13 of the power module substrate 10 having the metal layer 13 formed on the surface (the lower surface in FIG. 1) and the heat sink that is the magnesium-based composite material 20 are joined together.

The ceramic substrate 11 is made of, for example, ceramics such as Si ₃ N ₄ (silicon nitride), AlN (aluminum nitride), and Al ₂ O ₃ (alumina) that are excellent in insulation and heat dissipation. The thickness of the ceramic substrate 11 is in the range of 0.2 mm to 1.5 mm, for example.

  The circuit layer 12 is made of copper or a copper alloy. The circuit layer 12 is formed, for example, by brazing and bonding an oxygen-free copper plate having a purity of 99.96% by mass or more to the ceramic substrate 11 with an active metal brazing material. The thickness of the circuit layer 12 is in the range of 0.1 mm or more and 3.0 mm or less, for example.

  The metal layer 13 is made of copper or a copper alloy. Similarly to the circuit layer 12, the metal layer 13 is formed by brazing an oxygen-free copper plate having a purity of 99.96% by mass or more to the ceramic substrate 11 with an active metal brazing material. The thickness of the metal layer 13 is in the range of 0.1 mm or more and 3.0 mm or less, for example.

  The magnesium-based composite material 20 is a carbonaceous member 21 filled with magnesium 22. Examples of the carbonaceous member 21 include carbon fibers and silicon carbide. An example of the magnesium-based composite material 20 is MgSiC in which magnesium is filled in silicon carbide. As a composition of MgSiC, silicon carbide is preferably 70% by volume or more. Examples of the magnesium 22 include pure magnesium composed of 99.8% by mass or more of magnesium and inevitable impurities, magnesium to which additive elements such as Li, Ag, Ni, Ca, Al, Zn, Mn, Si, Cu, and Zr are added, and A magnesium alloy made of inevitable impurities can be used. When using a magnesium alloy, the total amount of additive elements is preferably 20% by mass or less, in particular, Al is 3% by mass or less, Zn is 5% by mass or less, and other elements are each 10% by mass or less ( However, the amount of the additive element is 100 for the magnesium alloy). The thickness of the magnesium-based composite material 20 is in the range of 0.4 mm to 5.0 mm, for example.

  In the power module substrate with a heat sink according to the present embodiment, a titanium layer 31 is disposed between the metal layer 13 and the magnesium-based composite material 20 of the power module substrate 10. The thickness of the titanium layer 31 is preferably in the range of 1 μm to 84 μm.

  The titanium layer 31 is formed by solid-phase diffusion bonding a titanium foil to the metal layer 13 in a method for manufacturing a power module substrate with a heat sink, which will be described later. By this solid phase diffusion bonding, an intermetallic compound layer 51 containing copper and titanium is generated between the metal layer 13 and the titanium layer 31 of the power module substrate 10.

  The titanium layer 31 and the magnesium-based composite material 20 are joined via an additive element-magnesium-containing layer 41 including an additive element-magnesium phase. In the magnesium-based composite material 20, a diffusion layer 23 containing an additive element is formed on the surface in contact with the additive element-magnesium-containing layer 41. The additive element is any one of copper, nickel, silver, aluminum, and a combination of aluminum and silicon.

  The additive element-magnesium-containing layer 41 is a magnesium-based composite material by heating a bonding material disposed between the titanium layer 31 and the magnesium-based composite material 20 in a method for manufacturing a power module substrate with a heat sink described later. This is a layer formed by the magnesium in 20 being diffused into the bonding material to generate a liquid phase and solidifying the liquid phase. That is, the additive element in the additive element-magnesium-containing layer 41 is an element used as a bonding material in the method for manufacturing a power module substrate with a heat sink described later.

The additive element-magnesium-containing layer 41 preferably contains the additive element and magnesium in a molar ratio (added element: Mg) within the following range.
When the additive element is copper (Cu: Mg); 94: 6 to 99.9: 0.1
When the additive element is nickel (Ni: Mg); 95: 5 to 99.9: 0.1
When the additive element is silver (Ag: Mg); 95: 5-98: 2
When the additive element is aluminum and when the additive element is a combination of aluminum and silicon (Al: Mg); 75:25 to 98: 2
In addition, when Si is contained in the additive element-magnesium phase of the additive element-magnesium-containing layer 41 as in the case where the additive element is a combination of aluminum and silicon, Si is present as dispersed Mg ₂ Si grains. Yes.

  The diffusion layer 23 of the magnesium-based composite material 20 is a layer generated by diffusing additive elements into the magnesium-based composite material 20. The thickness of the diffusion layer 23 is preferably 0.1 mm or more. Here, the diffusion layer 23 is a layer having an additive element concentration of 3 at% or more in the magnesium-based composite material 20. Since the thickness of the diffusion layer 23 is 0.1 mm or more, the titanium layer 31 and the magnesium-based composite material 20 are reliably bonded.

  The power module substrate with a heat sink of the present embodiment can be used as a power module with a heat sink by mounting a power semiconductor element on the circuit layer 12 of the power module substrate.

Next, a method for manufacturing a power module substrate with a heat sink according to the present embodiment will be described with reference to FIG.
First, as shown in FIG. 2A, a power module substrate 10 and a titanium foil 30 are prepared, and a laminate 50 in which the metal layer 13 and the titanium foil 30 of the power module substrate 10 are solid-phase bonded. Is made.

Specifically, first, a copper plate made of oxygen-free copper is bonded to one surface and the other surface of the ceramic substrate 11 by an active metal brazing material, respectively, and the circuit layer 12 is connected to one surface and the other surface of the ceramic substrate 11. And the board | substrate 10 for power modules in which the metal layer 13 was formed is obtained. In addition, Ag-Cu-Ti brazing material, Ag-Ti brazing material, etc. are used for an active metal brazing material. And the metal layer 13 and the titanium foil 30 of the obtained power module substrate 10 were laminated, and the metal layer 13 and the titanium foil 30 were solid-phase bonded by heating while applying a load in the laminating direction. A laminate 50 is obtained. When the metal layer 13 and the titanium foil 30 are solid-phase bonded, the above-described intermetallic compound layer 51 is generated. The load at this time is preferably in the range of 5 kgf / cm ² or more and 15 kgf / cm ² or less. The heating temperature is preferably in the range of 640 ° C to 798 ° C. The heating time is preferably in the range of 30 minutes to 150 minutes. Heating is preferably performed in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum.

The titanium foil 30 acts as a barrier film and has an effect of preventing the metal layer 13 of the power module substrate 10 and the magnesium-based composite material 20 from coming into direct contact. In order to exhibit this effect, the titanium foil 30 preferably has a larger area than at least one of the metal layer 13 and the magnesium-based composite material 20 of the power module substrate 10.
Further, when the thickness of the titanium foil 30 is larger, an intermetallic compound of Cu and Ti grows at the time of joining (that is, at the time of heating), and even if the thickness of the titanium foil decreases, Since it can prevent that the metal layer 13 and the magnesium group composite material 20 contact directly, it is preferable. On the other hand, it is preferable that the titanium foil 30 is thinner because the thermal resistance is lower.
Considering these points, the thickness of the titanium foil 30 is preferably in the range of 3 μm to 85 μm, and more preferably in the range of 10 μm to 20 μm. The titanium layer 31 is thinner than the titanium foil 30 due to diffusion during heating.

Next, as shown in FIG. 2B, the obtained laminate 50 and the magnesium-based composite material 20 are laminated through the bonding material 40 and heated while applying a load in the lamination direction. The load at this time is preferably in the range of 5 kgf / cm ² or more and 15 kgf / cm ² or less. The heating temperature is preferably in the range of 440 ° C to 650 ° C. The heating time is preferably in the range of 1 minute to 30 minutes. Heating is preferably performed in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum.

  By laminating the laminated body 50 and the magnesium-based composite material 20 via the bonding material 40 and heating, the magnesium 22 of the magnesium-based composite material 20 diffuses into the bonding material 40 to generate a liquid phase. And the above-mentioned additional element-magnesium content layer 41 produces | generates by solidifying a liquid phase by cooling. In addition, due to further diffusion of magnesium 22, the melting point of the liquid phase rises, and the liquid phase may solidify by so-called isothermal solidification that maintains the heating temperature. Then, the titanium foil 30 and the magnesium-based composite material 20 are liquid phase bonded.

As the bonding material 40, a bonding material made of copper, nickel, silver, aluminum, or an alloy of aluminum and silicon can be used.
As the aluminum used as the bonding material 40, pure aluminum (2N-Al) having a purity of 99% or higher, pure aluminum (3N-Al) having a purity of 99.9% or higher, pure aluminum (4N-Al) having a purity of 99.99% or higher. ), And aluminum such as A1050 and A6063 can be used.

It is preferable that the bonding material 40 exists uniformly between the titanium foil 30 and the magnesium-based composite material 20. For this reason, it is preferable that the bonding material 40 has the same area as the magnesium-based composite material 20.
Further, if the thickness of the bonding material 40 becomes too thin, the bonding strength between the titanium foil 30 and the magnesium-based composite material 20 is lowered, and the bonding reliability may be lowered. On the other hand, if the thickness is too thick, an excessive liquid phase is generated at the time of bonding, and the liquid phase leaks from between the titanium foil 30 and the magnesium-based composite material 20, which may cause a bump. Considering these points, the thickness of the bonding material 40 is preferably in the range of 2 μm to 100 μm, and more preferably in the range of 10 μm to 85 μm.

In addition, when using the joining material which consists of an alloy of aluminum and silicon for the joining material 40, content of silicon can be in the range of 5 mass% or more and 12.5 mass% or less. In particular, when the thickness of the bonding material 40 is relatively thin, it is easy to maintain the liquid phase by using a bonding material made of an alloy of aluminum and silicon, and the bonding reliability can be improved.
The alloy of aluminum and silicon preferably has a magnesium content of less than 1% by mass and particularly preferably 0.9% by mass or less. An alloy of aluminum and silicon having a magnesium content higher than the above amount may be difficult to form as a thin film-like bonding material.

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, the power module substrate 10, the titanium foil 30, the bonding material 40, and the magnesium-based composite material 20 can be bonded as follows.

FIG. 3 is a schematic explanatory view illustrating another method for manufacturing a power module substrate with a heat sink according to an embodiment of the invention.
First, as shown in FIG. 3A, the power module substrate 10 and the titanium foil 30 are solid-phase diffusion bonded by the above-described method, and the (metal layer 13) and the titanium foil 30 of the power module substrate 10 are bonded. A laminated body 50 in which is solid-phase bonded is produced.

Next, as shown in FIG. 3B, the laminate 50 is laminated so that the titanium foil 30 and the bonding material 40 face each other, and a load of 5 kgf / cm ² or more and 15 kgf / cm ² or less is applied in the lamination direction. And it heats at 550 degreeC or more and 640 degrees C or less, and produces the laminated body by which the bonding material 40 was solid-phase-bonded to the laminated body 50. FIG. Solid phase diffusion bonding can be performed in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum. In the case where an alloy of aluminum and silicon is used as the bonding material 40, it is more preferably performed in a vacuum. When aluminum having a purity of 99.99% or more is used as the bonding material 40, it is more preferable to perform solid phase diffusion bonding in an atmosphere of an inert gas such as nitrogen or argon.

Then, as shown in FIG. 3 (c), by laminating a laminate 50 laminate and magnesium-based composite material 20 bonding material 40 is a solid state welding to, in the stacking direction, 5 kgf / cm ² or more 15 kgf / cm ² A power module with a heat sink is applied by applying the following load and heating at 440 ° C. or more and 650 ° C. or less, and liquid-phase joining the magnesium-based composite material 20 to the laminate in which the joining material 40 is solid-phase joined to the laminate 50. A substrate can be obtained.

  In addition, as a method of producing the laminated body 50 in which the power module substrate 10 (metal layer 13) and the titanium foil 30 are solid-phase bonded, the following method can also be used.

FIG. 4 is a schematic explanatory view illustrating a method for manufacturing a laminate in which a power module substrate and a titanium foil 30 used in the embodiment of the present invention are solid-phase bonded.
First, as shown in FIG. 4A, the titanium foil 30, the copper plate to be the metal layer 13, the active metal brazing material (not shown), the ceramic substrate 11, the active metal brazing material (not shown), the circuit layer 12 The copper plates to be stacked are stacked in this order, and heated while being pressed in the stacking direction.

By such a method, as shown in FIG. 4B, the bonding of the ceramic substrate and the copper plate and the solid phase diffusion bonding of the titanium foil and the metal layer can be performed simultaneously. As the active metal brazing material, Ag—Cu—Ti brazing material or Ag—Ti is used, and the heating temperature is preferably in the range of 640 ° C. to 798 ° C. In addition, you may use the brazing material which combined Cu-P-Ni-Sn brazing material and Ti foil as an active metal brazing material. When using a brazing material in which a Cu—P—Ni—Sn brazing material and a Ti foil are combined, bonding is possible even when the heating temperature is relatively low (eg, 600 ° C. to 650 ° C.).
Note that the pressure in the stacking direction is preferably in the range of 5 kgf / cm ^{2 to} 15 kgf / cm ² .

  Furthermore, as another method of joining the power module substrate 10, the titanium foil 30, the joining material 40, and the magnesium-based composite material 20, it can be performed as follows.

FIG. 5 is a schematic explanatory view for explaining still another method for manufacturing a power module substrate with a heat sink according to an embodiment of the invention.
First, as shown in FIG. 5A, the power module substrate 10 is manufactured by the method described above, and the metal layer 13, the titanium foil 30, and the bonding material 40 of the power module substrate 10 are laminated in this order. By heating while applying a load in the stacking direction, a stacked body in which the metal layer 13, the titanium foil 30, and the bonding material 40 are solid-phase bonded is obtained. The load at this time is preferably in the range of 5 kgf / cm ² or more and 15 kgf / cm ² or less. The heating temperature is preferably in the range of 550 ° C to 650 ° C. The heating time is preferably in the range of 30 minutes to 150 minutes. Heating can be performed in an atmosphere of an inert gas such as nitrogen or in a vacuum. Preferably, it is performed in a vacuum. When heating is performed in a vacuum, it is preferable to use a bonding material made of any of copper, nickel, silver, and aluminum as the bonding material 40.

Then, as shown in FIG. 5B, the laminate in which the metal layer 13, the titanium foil 30, and the bonding material 40 are solid-phase bonded and the magnesium-based composite material 20 are combined with the magnesium-based composite material 20. Are stacked so as to face each other and heated while applying a load in the stacking direction. The load at this time is preferably in the range of 5 kgf / cm ² or more and 15 kgf / cm ² or less. The heating temperature is preferably in the range of 440 ° C to 650 ° C. The heating time is preferably in the range of below 30 minutes more than one minute. Heating is preferably performed in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum.

  A confirmation experiment conducted to confirm the effectiveness of the present invention will be described.

[Example of the present invention]
On both sides of an AlN insulating plate (40 mm × 40 mm, thickness 0.635 mm), an oxygen-free copper plate (37 mm × 37 mm, thickness 0.3 mm) having a purity of 99.96% by mass or more is used as an active metal brazing material ( A power module substrate made by brazing with Ag-27.4 mass% Cu-2.0 mass% Ti, and MgSiC (60 mm × 60 mm, thickness 5.0 mm, Mg content 14.7%) ) And prepared.

The power module substrate, the titanium foil and the bonding material shown in Table 1 are laminated and heated at a temperature of 640 ° C. for 60 minutes in a vacuum atmosphere while applying a bonding load of 12 kgf / cm ^{2 in} the lamination direction. Thus, a laminate composed of a power module substrate and a titanium foil was obtained.
The obtained laminate and MgSiC were laminated through the bonding materials shown in Table 1, and heated at a temperature of 610 ° C. for 15 minutes in a nitrogen atmosphere while applying a bonding load of 15 kgf / cm ² in the lamination direction. Then, a power module substrate with a heat sink was produced.

[Conventional example 1]
On both sides of an AlN insulating layer (40 mm × 40 mm, thickness 1.0 mm), an oxygen-free copper plate (37 mm × 37 mm, thickness 0.3 mm) having a purity of 99.96% by mass or more is applied to an active metal brazing material ( MgSiC (60 mm × 60 mm, thickness 5.0 mm, Mg content 14.7% by volume) was prepared by brazing and bonding with Ag-27.4 mass% Cu-2.0 mass% Ti). ) Was soldered using Sn—Sb solder (thickness: 0.3 mm) to obtain a power module substrate with a heat sink of Conventional Example 1.

  The following evaluation was performed about the board | substrate for power modules with a heat sink of the obtained example of this invention and a prior art example. The evaluation results are shown in Table 1.

(With or without a bump)
The presence or absence of a bump was evaluated by visually observing a power module substrate with a heat sink, and “も の” when the bump was generated, and “」 ”when it was not.

(Thermal resistance)
The thermal resistance was measured as follows. A heater chip as a semiconductor element was mounted on each power module substrate with a heat sink, heated with 100 W of power, and the temperature of the heater chip was measured using a thermocouple. Moreover, the power module with a heat sink on which the heater chip was mounted was fixed to the cooler, and the temperature of the cooling medium (ethylene glycol: water = 9: 1) flowing through the cooler was measured. And the value which divided the temperature difference of a heater chip | tip and the temperature of a cooling medium with electric power was made into thermal resistance.

(Measurement of diffusion layer thickness)
The thickness of the diffusion layer was determined by conducting quantitative line analysis in the stacking direction from the titanium layer to MgSiC using the energy dispersive X-ray analyzer Genesis manufactured by EDAX Division of AMETEK, and the concentration of the additive element from the bonding interface was 3 at%. The distance to the lower boundary was taken as the thickness of the diffusion layer. However, since the void is measured in the region where the total concentration of the additive element + Mg + Si is 30 at% or less, this region is not considered in the measurement of the thickness of the diffusion layer. Further, SiC is measured at a portion where the Si concentration is 30 at% or more, and this region is not taken into consideration for the thickness measurement of the diffusion layer.

(Measurement of thickness of titanium layer)
The thickness of the titanium layer was measured from the cross-sectional photograph observation by SEM with respect to the produced power module substrate with a heat sink.
The area of the titanium layer was measured in a 2000 × field of view (length 64.4 μm, width 74.7 μm), and divided by the width of the measurement field, the thickness of the titanium layer was determined. The average of the five fields of view was the thickness of the titanium layer.

(Initial joining rate)
The bonding rate between the power module substrate and the heat sink was evaluated. Specifically, in the power module substrate with a heat sink, the bonding rate at the interface between the metal layer of the power module substrate and the heat sink was evaluated using an ultrasonic flaw detector and calculated from the following equation. Here, the initial bonding area is an area to be bonded before bonding, that is, a metal layer area. In the ultrasonic flaw detection image, the non-joined part is indicated by a white part in the joined part, and thus the area of the white part is defined as the non-joined part area.
(Bonding rate (%)) = {(initial bonding area) − (non-bonding area)} / (initial bonding area) × 100

(Joint rate after thermal cycle)
The joint ratio after the thermal cycle is -40 ° C x 3 minutes ← → 150 ° C x in the liquid phase (Fluorinert) with respect to the power module substrate with heat sink using TSB-51 manufactured by Espec Corp. 1000 cycles of 7/7 were implemented, and the joining rate was evaluated by the same method as described above.

  From the results shown in Table 1, the power module substrate with a heat sink manufactured in the present invention example has a lower thermal resistance than the conventional example 1 using solder, a higher bonding rate after the thermal cycle, and a higher bonding reliability. It turns out that it is the board | substrate for power modules with an excellent heat sink. In Example 5 of the present invention, a bump was confirmed, but there was no problem in use.

DESCRIPTION OF SYMBOLS 10 Power module substrate 11 Ceramic substrate 12 Circuit layer 13 Metal layer 20 Magnesium group composite material 21 Carbonaceous member 22 Magnesium or magnesium alloy 23 Diffusion layer 30 Titanium foil 31 Titanium layer 40 Joining material 41 Additive element-magnesium containing layer 50 Laminate 51 Intermetallic compound layer

Claims (7)

A metal member made of copper or a copper alloy, and a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member, is a method of manufacturing a joined body,
A titanium foil is disposed between the metal member and the magnesium-based composite material,
The metal member and the titanium foil are solid-phase bonded, and the titanium foil and the magnesium-based composite material are liquid-phased using a bonding material made of copper, nickel, silver, aluminum, or an alloy of aluminum and silicon. The manufacturing method of the joined body characterized by bonding.   The method for producing a joined body according to claim 1, wherein the thickness of the titanium foil is in a range of 3 µm to 85 µm.   The method for manufacturing a joined body according to claim 1, wherein the joining material is a joining material made of an alloy of aluminum and silicon. A power provided with an insulating layer, a circuit layer made of copper or a copper alloy formed on one surface of the insulating layer, and a metal layer made of copper or a copper alloy formed on the other surface of the insulating layer A method of manufacturing a power module substrate with a heat sink, in which a metal layer of a module substrate and a heat sink, which is a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member, are joined,
A titanium foil is disposed between the metal layer and the magnesium-based composite material,
The metal layer and the titanium foil are solid-phase bonded, and the titanium foil and the magnesium-based composite material are liquid-phase bonded using a bonding material made of copper, nickel, silver, an alloy of aluminum and silicon. A method for manufacturing a power module substrate with a heat sink. A metal member made of copper or a copper alloy, and a magnesium-based composite material in which a carbonaceous member is filled with magnesium or a magnesium alloy is a joined body,
A titanium layer is disposed between the metal member and the magnesium-based composite material;
The metal member and the titanium layer are joined via an intermetallic compound layer containing copper and titanium,
The magnesium-based composite material in which the titanium layer and the magnesium-based composite material are joined via an additive element-magnesium-containing layer including an additive element-magnesium phase and in contact with the additive element-magnesium-containing layer. Is formed with a diffusion layer containing an additive element,
The joined body is characterized in that the additive element is any one of copper, nickel, silver, aluminum, and a combination of aluminum and silicon.   The joined body according to claim 5, wherein a thickness of the titanium layer is in a range of 1 μm to 84 μm. A power provided with an insulating layer, a circuit layer made of copper or a copper alloy formed on one surface of the insulating layer, and a metal layer made of copper or a copper alloy formed on the other surface of the insulating layer A power module substrate with a heat sink, in which a metal layer of the module substrate and a heat sink, which is a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member, are joined,
A titanium layer is disposed between the metal layer and the magnesium-based composite material;
The metal layer and the titanium layer are bonded via an intermetallic compound layer containing copper and titanium,
The magnesium-based composite material in which the titanium layer and the magnesium-based composite material are joined via an additive element-magnesium-containing layer including an additive element-magnesium phase and in contact with the additive element-magnesium-containing layer. Is formed with a diffusion layer containing an additive element,
The power module substrate with a heat sink, wherein the additive element is any one of copper, nickel, silver, aluminum, and a combination of aluminum and silicon.

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