JP2017120828A - Method for manufacturing assembly, method for manufacturing substrate for heat sink-equipped power module, assembly, and substrate for heat sink-equipped power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an assembly, which makes it possible to bond a metal member of aluminum, an aluminum alloy or the like, which is in wide use as a metal layer of a substrate for a power module, to a magnesium-based composite material typified by MgSiC which can be utilized as a heat sink with superior bonding reliability without using solder.SOLUTION: A method for manufacturing an assembly arranged by bonding a metal member made of aluminum or an aluminum alloy to a magnesium-based composite material arranged by filling magnesium or a magnesium alloy in a carbonaceous member comprises the steps of: disposing a piece of titanium foil between the metal member and the magnesium-based composite material; bonding the metal member to the piece of titanium foil; and bonding the piece of titanium foil to the magnesium-based composite material by use of a bonding material including any of copper, nickel, silver and aluminum by liquid phase bonding.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a joined body in which a metal member made of aluminum or an aluminum 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 the metal layer of the power module substrate, 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 inventor, when the aluminum member used as the metal layer of the power module substrate and MgSiC are heated by direct contact, a large amount of Al—Mg liquid phase is generated, and the aluminum member and MgSiC It has been found difficult to join the aluminum member and MgSiC with excellent joint reliability. The reason why a large amount of Al—Mg liquid phase is generated is that when Al and Mg are in contact with each other and heated to a temperature higher than the eutectic temperature of Al and Mg, an Al—Mg mixed melt is generated. Since the aluminum member and MgSiC to be joined each have a thickness of about several millimeters, a large amount of Al and Mg will continue to be supplied to the joining interface where the Al-Mg mixed melt is generated. It is thought that the Al-Mg mixed melt leaks from the gap.

  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 aluminum or aluminum alloy that is 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 aluminum or aluminum 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 problems, a method for manufacturing a joined body according to the present invention includes a metal member made of aluminum or an aluminum alloy, and a carbonaceous member filled with magnesium or a magnesium alloy (simply referred to as magnesium in the present application). A method for producing a joined body in which a magnesium-based composite material is joined, wherein a titanium foil is disposed between the metal member and the magnesium-based composite material, and the metal member and the titanium foil are joined together. The titanium foil and the magnesium-based composite material are liquid-phase bonded using a bonding material made of copper, nickel, silver, or aluminum. In addition, in this invention, copper, nickel, silver, and aluminum 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, it is possible to suppress the generation of a large amount of Al-Mg mixed melt. 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 aluminum. Among copper, nickel, silver, and aluminum that can be used as the bonding material, aluminum and magnesium and a molten mixture are generated at the lowest temperature, so that the time during which the liquid phase can be maintained is increased, 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.

  In the method for producing a joined body of the present invention, when the titanium foil and the magnesium-based composite material are liquid-phase bonded using a bonding material, the magnesium-based composite material and the titanium foil are interposed between the titanium-based composite material and the titanium foil. Magnesium may be interposed. According to this configuration, since the magnesium content in the melt of the bonding material can be made uniform, the magnesium-based composite material and the titanium foil can be bonded with a uniform strength. Therefore, it is possible to manufacture a bonded body with higher bonding reliability.

  Furthermore, in the method for manufacturing a joined body of the present invention, it is preferable that the titanium foil and the metal member are joined by liquid phase joining or solid phase diffusion joining using a joining material. According to this structure, the said titanium foil and the said metal member can be joined more firmly. Therefore, it is possible to manufacture a bonded body with higher bonding reliability.

  Furthermore, in the method for producing a joined body of the present invention, when the titanium foil and the metal member are subjected to liquid phase joining, the joining material is copper, nickel, silver, magnesium, silicon, an alloy of aluminum and silicon, aluminum A clad material in which an alloy skin of aluminum, silicon and magnesium is laminated on one or both sides of an alloy of aluminum and magnesium, an alloy of aluminum, silicon and magnesium, or an aluminum alloy core material is preferable. According to this structure, the said titanium foil and the said metal member can be joined still more firmly. 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 of the present invention comprises an insulating layer, a circuit layer formed on one surface of the insulating layer, and aluminum or an aluminum alloy formed on the other surface of the insulating layer. A method for producing a power module substrate with a heat sink, in which a metal layer of a power module substrate provided with a metal layer and a heat sink, which is a magnesium-based composite material in which magnesium is filled in a carbonaceous member, are joined together A titanium foil is disposed between the metal layer and the magnesium-based composite material, the metal layer and the titanium foil are joined, and the titanium foil and the magnesium-based composite material are combined with copper, nickel, It is characterized by performing liquid phase bonding using a bonding material made of either silver or aluminum.

  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, it is possible to suppress the generation of a large amount of Al-Mg mixed melt. 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 aluminum or an aluminum alloy and a magnesium-based composite material in which magnesium is filled in a carbonaceous member are joined, and the metal member and the magnesium A titanium layer is disposed between the base composite material, and the metal member and the titanium layer are joined via an intermetallic compound layer containing aluminum and titanium, and the titanium layer and the magnesium base composite A diffusion layer containing an additive element is added to the magnesium-based composite material in which the material is bonded via the additive element-magnesium-containing layer including the additive element-magnesium phase and in contact with the additive element-magnesium-containing layer. The additive element is any one of copper, nickel, silver, and aluminum.

  According to the structure of the joined body, the titanium layer and the magnesium-based composite material are joined via the aluminum-magnesium-containing layer containing an additive element-magnesium phase, and are in contact with the additive element-magnesium-containing layer. By forming a diffusion layer containing aluminum in the magnesium-based composite material, 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 aluminum 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, Al 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.

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

  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 aluminum-magnesium-containing layer containing an additive element-magnesium phase, and the addition By forming a diffusion layer containing aluminum in the magnesium-based composite material that is in contact with the element-magnesium-containing layer, the bonding strength between the magnesium-based composite material and the titanium layer is increased. In addition, since the metal member of the power module substrate and the titanium layer are bonded via an intermetallic compound layer containing aluminum and titanium, the bonding strength between the metal member and the titanium layer is increased. . 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 joining body which can join metal members, such as aluminum and aluminum alloy, and the magnesium group composite material represented by MgSiC by soldering without outstanding soldering reliability, and a heat sink It is possible to provide a method for manufacturing a power module substrate. In addition, according to the present invention, it is possible to provide a joined body in which a metal member such as aluminum or aluminum alloy and a magnesium-based composite material are joined without using solder, and a power module substrate with a heat sink. 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 manufacturing method of the board | substrate for power modules with a heat sink which is 1st 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 2nd 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 3rd embodiment of this invention. It is a schematic explanatory drawing of the board | substrate for power modules with a heat sink which is embodiment of this invention.

(First embodiment)
Hereinafter, an embodiment of a method for manufacturing a power module substrate with a heat sink according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory view illustrating a method for manufacturing a power module substrate with a heat sink according to the first embodiment of the present invention.

  1, a power module substrate 10 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 surface of the ceramic substrate 11. And a metal layer 13 made of aluminum or aluminum alloy formed on the lower surface (in FIG. 1, the lower surface).

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 formed, for example, by bonding a metal plate to one surface of the ceramic substrate 11. Examples of the metal plate include a copper plate made of copper or a copper alloy, and an aluminum plate made of aluminum or an aluminum alloy. The circuit layer 12 may be a laminate of two or more metal layers. Examples of the laminate that can be used as the circuit layer 12 include a laminate in which a copper plate is laminated on an aluminum plate by solid phase diffusion bonding. The circuit layer 12 preferably has a purity of 99% by mass (2N) or more. The thickness of the circuit layer 12 is in the range of 0.1 mm or more and 6.0 mm or less, for example.

  The metal layer 13 is formed, for example, by bonding an aluminum plate made of aluminum or an aluminum alloy to one surface of the ceramic substrate 11. The metal layer 13 is preferably aluminum having a purity of 99% by mass (2N) or more, and more preferably aluminum having a purity of 99.99% by mass (4N) or more. The thickness of the metal layer 13 is in the range of 0.1 mm or more and 6.0 mm or less, for example.

  A magnesium-based composite material 20 used as a heat sink for a power module substrate with a heat sink 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 method for manufacturing a power module substrate with a heat sink according to this embodiment, a titanium foil 30 is disposed between the metal layer 13 of the power module substrate 10 and the magnesium-based composite material 20. Then, the magnesium-based composite material 20 and the titanium foil 30 are bonded, and the titanium foil 30 and the metal layer 13 are liquid-phase bonded to bond the metal layer 13 of the power module substrate 10 and the magnesium-based composite material 20 together. To do.

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 titanium foil 30 is thicker, even if the intermetallic compound of Al and Ti grows at the time of joining (ie, during heating) and the thickness of the titanium foil decreases, the metal of the power module substrate 10 is increased. Since it can prevent that the layer 13 and the magnesium-based 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.

  In the first embodiment, the heat sink joining material 40 is used for joining the titanium foil 30 and the magnesium-based composite material 20. As the heat sink bonding material 40, a bonding material made of any of copper, nickel, silver, and aluminum can be used. Preferably, a foil material of aluminum or aluminum alloy is used. Examples of the aluminum alloy include an alloy of aluminum and silicon (Al—Si), an alloy of aluminum and magnesium (Al—Mg), and an alloy of aluminum, silicon and magnesium (Al—Si—Mg). For example, a double-sided clad material or a single-sided clad material in which an aluminum alloy (for example, A3003) is used as a core material and a skin material is an Al—Si—Mg alloy can also be used.

The heat sink bonding material 40 is preferably present uniformly between the titanium foil 30 and the magnesium-based composite material 20. For this reason, it is preferable that the bonding material 40 for heat sink bonding has the same area as the metal layer 13.
Moreover, if the thickness of the bonding material 40 for heat sink bonding 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 for heat sink bonding is preferably in the range of 2 μm to 100 μm, and more preferably in the range of 10 μm to 85 μm.

  In the first embodiment, the power module substrate bonding material 50 is used for bonding the metal layer 13 of the power module substrate 10 and the titanium foil 30. The power module substrate bonding material 50 includes copper, nickel, silver, magnesium, silicon, an alloy of aluminum and silicon (Al—Si), an alloy of aluminum and magnesium (Al—Mg), or aluminum, silicon and magnesium. (Al—Si—Mg) can be used. For example, a double-sided clad material or a single-sided clad material in which an aluminum alloy (for example, A3003) is used as a core material and a skin material is an Al—Si—Mg alloy can also be used.

The power module substrate bonding material 50 is preferably present uniformly between the metal layer 13 and the titanium foil 30. For this reason, it is preferable that the bonding member 50 for power module substrate bonding has the same area as the metal layer 13.
Further, the thickness of the power module substrate bonding material 50 is preferably 100 μm or less, preferably 75 μm or less, and more preferably 50 μm or less. 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 metal layer 13, which may cause a bump.

In the first embodiment, as shown in FIG. 1, the power module substrate bonding material 50 is interposed between the power module substrate 10 and the magnesium-based composite material 20 from the metal layer 13 side of the power module substrate 10. Then, the titanium foil 30, the bonding material 40 for heat sink bonding, and the magnesium-based composite material 20 are stacked in this order to obtain a stacked body.
Next, the obtained laminated body is heated while applying a load in the laminating direction to produce a power module substrate with a heat sink. The load applied to the laminate is preferably in the range of 5 kgf / cm ² or more and 15 kgf / cm ² or less. The heating temperature of the laminate is preferably in the range of 460 ° C. or more and 610 ° C. or less. The heating time of the laminate is preferably in the range of 1 minute to 30 minutes. The laminated body is preferably heated in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum.
By heating this laminate, a liquid phase is generated between the metal layer 13 and the titanium foil 30. Further, between the titanium foil 30 and the magnesium-based composite material 20, a liquid phase is generated by the diffusion of the magnesium 22 of the magnesium-based composite material 20 into the bonding material 40 for heat sink bonding. And the liquid phase solidifies 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.

(Second embodiment)
Next, a second embodiment of the method for manufacturing a power module substrate with a heat sink of the present invention will be described.
FIG. 2 is a schematic explanatory view illustrating a method for manufacturing a power module substrate with a heat sink according to the second embodiment of the present invention.

In the second embodiment, a magnesium foil 60 is interposed between the heat sink bonding material 40 and the magnesium-based composite material 20. The magnesium foil 60 may be interposed between the titanium foil 30 and the bonding material 40 for heat sink bonding.
The magnesium 22 of the magnesium-based composite material 20 is diffused into the heat sink bonding material 40 by heating at the time of bonding of the titanium foil 30 and the magnesium-based composite material 20, and the liquid phase (copper, nickel contained in the heat sink bonding material 40) However, since the carbonaceous member 21 is present on the surface of the magnesium-based composite material 20, the carbonaceous member 21 is used for joining heat sinks. There is a possibility that diffusion of magnesium 22 into the material 40 may be suppressed. If the diffusion of the magnesium 22 is insufficient, the generation of the liquid phase becomes non-uniform, and it may be difficult to join the titanium foil 30 and the magnesium-based composite material 20 with a uniform strength. The magnesium foil 60 has an effect of uniformly diffusing magnesium and generating a liquid phase into the heat sink bonding material 40 and bonding the titanium foil 30 and the magnesium-based composite material 20 with uniform strength. For this reason, it is preferable that the magnesium foil 60 has the same area as the bonding material 40 for heat sink bonding.
As the magnesium foil 60, a magnesium foil having a purity of 89.0% by mass or more and 99.9% by mass or less may be used.
If the magnesium foil 60 is too thick, the liquid phase generated between the heat sink bonding material 40 and the magnesium foil 60 does not reach the magnesium-based composite material 20 and the titanium foil 30 and the magnesium-based composite material 20. However, there is a possibility that the bondability is lowered. For this reason, the thickness of the magnesium foil 60 may be 100 μm or less, desirably 50 μm or less, and more desirably 10 μm or less.

  In the second embodiment, as shown in FIG. 2, the power module substrate bonding material 50 is interposed between the power module substrate 10 and the magnesium-based composite material 20 from the metal layer 13 side of the power module substrate 10. Then, the titanium foil 30, the heat sink bonding material 40, the magnesium foil 60, and the magnesium-based composite material 20 are laminated in this order to obtain a laminate. Next, the obtained laminated body is heated while applying a load in the laminating direction to produce a power module substrate with a heat sink. The load, the heating temperature, the heating time, and the heating atmosphere applied when heating the laminate are the same as in the first embodiment.

(Third embodiment)
Next, a third embodiment of the method for manufacturing a power module substrate with a heat sink of the present invention will be described.
FIG. 3 is a schematic explanatory view illustrating a method for manufacturing a power module substrate with a heat sink according to the third embodiment of the present invention.

In the third embodiment, the power module substrate bonding material 50 used for bonding the metal layer 13 of the power module substrate 10 and the titanium foil 30 in the first embodiment is omitted.
That is, in the third embodiment, the metal layer 13 and the titanium foil 30 are joined by solid phase diffusion. In the third embodiment, the metal layer 13 is preferably made of high-purity aluminum, particularly 4N or higher-purity aluminum.

In the third embodiment, as shown in FIG. 3, the titanium foil 30 and the heat sink joining material are disposed between the power module substrate 10 and the magnesium-based composite material 20 from the metal layer 13 side of the power module substrate 10. 40 and the magnesium-based composite material 20 are laminated in this order to obtain a laminate. Next, the obtained laminated body is heated while applying a load in the laminating direction to produce a power module substrate with a heat sink. The load, the heating temperature, the heating time, and the heating atmosphere applied when heating the laminate are the same as in the first embodiment. The bonding load is more preferably 12 kgf / cm ² or more and 15 kgf / cm ² or less.

  As mentioned above, although embodiment of the manufacturing method of the board | substrate for power modules with a heat sink was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.

  For example, in the third embodiment, the magnesium foil 60 may be interposed between the heat sink bonding material 40 and the magnesium-based composite material 20 or between the titanium foil 30 and the heat sink bonding material 40. .

  In the first to third embodiments, the joining of the titanium foil 30 and the magnesium-based composite material 20 and the joining of the metal layer 13 and the titanium foil 30 are performed at the same time. May be. For example, after joining the titanium foil 30 and the magnesium-based composite material 20, the metal layer 13 and the titanium foil 30 may be joined, or after joining the metal layer 13 and the titanium foil 30, the titanium foil 30. And the magnesium-based composite material 20 may be joined.

Next, a power module substrate with a heat sink according to an embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a schematic explanatory view of a power module substrate with a heat sink according to an embodiment of the present invention.

  The power module substrate with a heat sink shown in FIG. 4 is manufactured by the above-described embodiment of the method for manufacturing the power module substrate with a heat sink. 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. 4) of the ceramic substrate 11, and the other of the ceramic substrate 11. The metal layer 13 of the power module substrate 10 provided with the metal layer 13 made of aluminum or aluminum alloy formed on the surface (the lower surface in FIG. 4), and the carbonaceous member 21 was filled with magnesium 22 The heat sink which is the magnesium-based composite material 20 is joined.

  A titanium layer 31 is disposed between the metal layer 13 of the power module substrate 10 and the magnesium-based composite material 20. The thickness of the titanium layer 31 is preferably in the range of 1 μm to 84 μm.

  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, and the magnesium in contact with the additive element-magnesium-containing layer 41 A diffusion layer 23 containing an additive element is formed in the matrix composite material 20. The additive element is any one of copper, nickel, silver, and aluminum.

The additive element-magnesium-containing layer 41 is a layer formed by diffusion of magnesium to the heat sink bonding material 40 by heating at the time of bonding to generate a liquid phase and solidify the liquid phase.
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 (Al: Mg); 75:25 to 98: 2
In addition, in the additive element-magnesium phase of the additive element-magnesium-containing layer 41, Mg ₂ Si particles are dispersed when the heat sink joining material 40 (eg, Al—Si brazing material) containing Si is used. Exist.

  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 metal layer 13 and the titanium layer 31 of the power module substrate 10 are joined via an intermetallic compound layer 51 containing aluminum and titanium. When the bonding member 50 for power module substrate bonding is used to bond the titanium layer 31 and the metal layer 13 to the intermetallic compound layer 51, the aluminum melt generated by heating at the time of bonding and the titanium foil 30 It is a layer produced | generated by reaction of these. As the power module substrate bonding material 50, an Al—Si alloy, an Al—Mg alloy, an Mg—Si—Al alloy, or an aluminum alloy (for example, A3003) is used as a core material, and a skin material is Al—Si—. When a double-sided clad material or a single-sided clad material made of an Mg alloy is used, the intermetallic compound layer 51 contains aluminum, titanium, and silicon. Further, when the metal layer 13 and the titanium layer 31 are bonded by solid phase diffusion without using the power module substrate bonding material 50, the intermetallic compound layer 51 includes the metal layer 13 and the titanium layer. It becomes a layer produced | generated by reaction with 31. The titanium layer 31 is thinner than the titanium foil 30 due to diffusion during heating.

  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.

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

[Invention Examples 1 to 21]
A power module substrate having a 4N aluminum layer (37 mm × 37 mm, thickness 0.4 mm) formed on both sides of an AlN insulating layer (40 mm × 40 mm, thickness 1.0 mm), and MgSiC (60 mm × 60 mm, thickness) 5.0 mm, Mg content 14.7% by volume).
Between the power module substrate and MgSiC, the magnesium foil, the heat sink bonding material, titanium foil, and the power module substrate bonding material shown in Table 1 are MgSiC / magnesium foil / heat sink bonding material / titanium foil. A laminate was obtained by laminating in the order of: / a power module substrate bonding material / a power module substrate. Next, the obtained laminate was heated in a nitrogen atmosphere at a temperature of 610 ° C. for 15 minutes while applying a bonding load of 15 kgf / cm ^{2 in} the laminating direction to produce a power module substrate with a heat sink.

[Conventional example 1]
MgSiC (60 mm × 60 mm, thickness) on a power module substrate on which a 4N aluminum layer (37 mm × 37 mm, thickness 0.4 mm) is formed on both sides of an AlN insulating layer (40 mm × 40 mm, thickness 1.0 mm) 5.0 mm, Mg content 14.7% by volume) 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 2.

(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.
(Joining rate) = {(initial joining area) − (non-joining area)} / (initial joining area) × 100

(Joint rate after thermal cycle)
The joint ratio after the thermal cycle is -40 ° C x 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 of Table 2, the power module substrate with a heat sink produced in the example of the present invention has a lower thermal resistance than the conventional example 1 using solder, a higher joining rate after the thermal cycle, and a higher joining reliability. It turns out that it is the board | substrate for power modules with an excellent heat sink. In the present invention examples 5, 10, and 12 where the thicknesses of the magnesium foil, the heat sink bonding material, and the power module substrate bonding material were thick, the bumps were confirmed, but there was no problem in using them. Met.

DESCRIPTION OF SYMBOLS 10 Power module substrate 11 Ceramic substrate 12 Circuit layer 13 Metal layer 20 Magnesium-based composite material 21 Carbonaceous member 22 Magnesium or magnesium alloy 23 Diffusion layer 30 Titanium foil 31 Titanium layer 40 Heat sink joining material 41 Additive element-magnesium-containing layer 50 Power Module Substrate Bonding Material 51 Intermetallic Compound Layer 60 Magnesium Foil

Claims (10)

A metal member made of aluminum or an aluminum 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 bonded, and the titanium foil and the magnesium-based composite material are liquid-phase bonded using a bonding material made of copper, nickel, silver, or aluminum. Body manufacturing method.   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 aluminum.   The magnesium is interposed between the magnesium-based composite material and the titanium foil when the titanium foil and the magnesium-based composite material are liquid-phase bonded using the bonding material. The manufacturing method of the conjugate | zygote as described in any one of Claim 3.   The said metal member and the said titanium foil are joined by the liquid phase joining using a joining material, or solid phase diffusion joining, The manufacture of the conjugate | zygote as described in any one of Claims 1-4 characterized by the above-mentioned. Method.   The metal member and the titanium foil are placed on one or both surfaces of copper, nickel, silver, magnesium, silicon, an alloy of aluminum and silicon, an alloy of aluminum and magnesium, an alloy of aluminum, silicon, and magnesium, or an aluminum alloy core material. 6. The method for manufacturing a joined body according to claim 5, wherein liquid phase joining is performed using a joining material made of any one of clad materials obtained by laminating aluminum, silicon, and magnesium alloy skin materials. A metal layer of a power module substrate, comprising: an insulating layer; a circuit layer formed on one surface of the insulating layer; and a metal layer made of aluminum or an aluminum alloy formed on the other surface of the insulating layer. And a heat sink that is a magnesium-based composite material in which a carbonaceous member is filled with magnesium or a magnesium alloy is a method of manufacturing a power module substrate with a heat sink formed by bonding,
A titanium foil is disposed between the metal layer and the magnesium-based composite material,
The heat sink, wherein the metal layer and the titanium foil are bonded, and the titanium foil and the magnesium-based composite material are liquid-phase bonded using a bonding material made of copper, nickel, silver, or aluminum. Method for manufacturing a power module substrate. A metal member made of aluminum or an aluminum alloy and a magnesium-based composite material in which magnesium or a magnesium alloy is filled in a carbonaceous member 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 aluminum 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, wherein the additive element is any one of copper, nickel, silver, and aluminum.   The joined body according to claim 8, wherein a thickness of the titanium layer is in a range of 1 µm to 84 µm. A metal layer of a power module substrate, comprising: an insulating layer; a circuit layer formed on one surface of the insulating layer; and a metal layer made of aluminum or an aluminum alloy formed on the other surface of the insulating 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 is a power module substrate with a heat sink formed by bonding,
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 aluminum 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, and aluminum.

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