JP5577980B2 - Power module substrate with heat sink, power module, and method for manufacturing power module substrate with heat sink - Google Patents

Description

  The present invention relates to a power module substrate with a heat sink used in a semiconductor device that controls a large current and a high voltage, a power module, and a method for manufacturing a power module substrate with a heat sink.

Among semiconductor elements, a power module for supplying power has a relatively high calorific value, and for example, AlN (aluminum nitride), Al ₂ O ₃ (alumina), Si ₃ N ₄ ( A power module with a heat sink in which a first metal plate is joined to one surface side of a ceramic substrate made of silicon nitride) and the like, and a heat sink is connected to the other surface side of the ceramic substrate via a second metal plate A substrate is used.
In such a power module substrate with a heat sink, a circuit pattern is formed on a first metal plate, and a semiconductor chip of a power element is mounted on the first metal plate via a solder material.

  For example, Patent Document 1 proposes a power module substrate in which a first metal plate and a second metal plate are copper plates, and the copper plates are directly bonded to a ceramic substrate by a DBC method. Further, as shown in FIG. 1 of Patent Document 1, a power module substrate with a heat sink is configured by bonding an aluminum heat sink to the power module substrate using an organic heat-resistant adhesive. .

  Patent Document 2 proposes a power module substrate using aluminum plates as the first metal plate and the second metal plate. In the power module substrate, a power module substrate with a heat sink is configured by joining a second metal plate to the heat sink by brazing.

  Further, Patent Document 3 proposes a method in which a metal plate is bonded to one surface of a ceramic substrate, and an aluminum heat sink is directly formed on the other surface of the ceramic substrate by a casting method. And it is disclosed that an aluminum plate and a copper plate are used as a metal plate.

Japanese Patent Laid-Open No. 04-162756 Japanese Patent No. 3171234 Japanese Patent Laid-Open No. 2002-075651

By the way, in the power module substrate with a heat sink described in Patent Document 1, since the copper plate is disposed between the aluminum heat sink and the ceramic substrate, the difference in thermal expansion coefficient between the heat sink and the ceramic substrate. There is a problem that the thermal strain caused by the above cannot be sufficiently relaxed in this copper plate, and the ceramic substrate is likely to be cracked during a thermal cycle load.
In addition, Patent Document 1 describes that thermal strain is alleviated by an organic heat resistant adhesive interposed between the heat sink and the second metal plate, but the organic heat resistant adhesive is interposed. As a result, the thermal resistance becomes high, and there is a problem that heat from a heating element such as an electrical component mounted on the first metal plate cannot be efficiently dissipated to the heat sink side.

In the power module substrate with a heat sink described in Patent Document 2, an aluminum plate is used as the first metal plate.
Here, when copper and aluminum are compared, since aluminum has lower thermal conductivity, when an aluminum plate is used as the first metal plate, the electrical components mounted on the first metal plate, etc. It is inferior to copper to spread and dissipate the heat from the heating element. For this reason, when the power density increases due to downsizing and high output of the electronic component, there is a possibility that heat cannot be sufficiently dissipated.

Furthermore, in the power module substrate with a heat sink described in Patent Document 3, since the aluminum heat sink is directly bonded to the ceramic substrate, the thermal distortion caused by the difference in the thermal expansion coefficient between the heat sink and the ceramic substrate. As a result, the ceramic substrate is easily cracked. In order to prevent this, in Patent Document 3, it is necessary to set the proof stress of the heat sink low. For this reason, the strength of the heat sink itself is insufficient, and handling is very difficult.
In addition, since the heat sink is formed by a casting method, the structure of the heat sink becomes relatively simple, a heat sink having a high cooling capacity cannot be formed, and heat dissipation cannot be promoted. It was.

  The present invention has been made in view of the above-described circumstances, can promote the dissipation of heat from a heating element such as an electronic component mounted on a first metal plate, and is capable of thermal cycling. An object of the present invention is to provide a highly reliable power module substrate with a heat sink, a power module, and a method for manufacturing a power module substrate with a heat sink that suppresses the occurrence of cracks in the ceramic substrate during loading.

In order to solve such problems and achieve the above object, a method for manufacturing a power module substrate with a heat sink according to the present invention includes a ceramic substrate and a first metal bonded to one surface of the ceramic substrate. A power module substrate with a heat sink, comprising: a plate; a second metal plate bonded to the other surface of the ceramic substrate; and a heat sink bonded to the other surface of the second metal plate. The first metal plate is made of copper or a copper alloy, and one surface of the first metal plate is a mounting surface on which electronic components are mounted, and the second metal plate is The heat resistance is made of aluminum having a strength of 30 N / mm ² or less, and the heat sink is made of a metal material having a strength of 100 N / mm ² or more, and has a thickness of 2 mm or more.

In the power module substrate with a heat sink having this configuration, the first metal plate having the mounting surface on which the electronic component is mounted is made of copper or a copper alloy, so that heat generated from the electronic component can be sufficiently expanded. Can promote heat dissipation.
In addition, since the second metal plate made of aluminum having a proof stress of 30 N / mm ² or less is disposed between the heat sink and the ceramic substrate, the heat caused by the difference in the thermal expansion coefficient between the heat sink and the ceramic substrate. The strain can be sufficiently relaxed by the second metal plate, and cracking of the ceramic substrate can be suppressed.
Furthermore, as described above, since the thermal strain can be reduced by the second metal plate, the heat sink is made of a metal material having a proof stress of 100 N / mm ² or more, and its thickness is 2 mm or more. The heat sink itself is highly rigid and easy to handle.
Moreover, since it is set as the structure which joins a heat sink to a 2nd metal plate, there is no restriction | limiting in the structure of a heat sink, and it can employ | adopt the heat sink excellent in the cooling capability.

Here, Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, Li, or the like is present on at least one of the bonding interface with the ceramic substrate or the bonding interface with the heat sink among the second metal plates. 1 type (s) or 2 or more types of additional element is solid-solving, and the sum total of the density | concentration of the said additional element in the joining interface vicinity of said 2nd metal plate is 0.01 mass% or more and 5 mass% It is preferably set within the following range.
In this case, since one or more additive elements of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga and Li are dissolved in the second metal plate, The joint interface side portion of the second metal plate is strengthened by solid solution. Thereby, the fracture | rupture in a 2nd metal plate part can be prevented.

  In addition, since the total concentration of the additive elements in the vicinity of the bonding interface in the second metal plate is 0.01% by mass or more, the bonding interface side portion of the second metal plate is surely solid-solution strengthened. can do. Further, since the total concentration of the additive elements in the vicinity of the bonding interface in the second metal plate is 5% by mass or less, the strength in the vicinity of the bonding interface of the second metal plate is excessively increased. When the thermal cycle is applied to the power module substrate, the thermal strain can be relaxed by the second metal plate, and the occurrence of cracks in the ceramic substrate can be suppressed.

Further, one or more of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li are added to the bonding interface with the ceramic substrate of the second metal plate. It is preferable that a high concentration portion of the additive element in which the concentration of the element is at least twice the concentration of the additive element in the second metal plate is formed.
In this case, a high concentration portion of the additive element in which the concentration of the additive element is twice or more the concentration of the additive element in the second metal plate is formed at the bonding interface of the second metal plate. The additive element atoms present in the vicinity of the interface can improve the bonding strength of the second metal plate. The concentration of the additive element in the second metal plate is the concentration of the additive element in a portion of the second metal plate that is away from the bonding interface by a certain distance (for example, 5 nm or more).

Here, the high concentration portion of the additive element is formed at the bonding interface with the ceramic substrate of the second metal plate, the ceramic substrate is made of Al ₂ O ₃ , and is bonded to the ceramic substrate. The mass ratio of Al, additive element, and O obtained by analyzing the bonding interface including the high concentration portion of the additive element formed at the interface by energy dispersive X-ray analysis is Al: additive element: O = 50 to 90 mass%. : 1-30 mass%: You may be 45 mass% or less.
Further, the high concentration portion of the additive element is formed at the bonding interface with the ceramic substrate in the second metal plate, the ceramic substrate is made of AlN, and is formed at the bonding interface with the ceramic substrate. The mass ratio of Al, additive element, O, and N analyzed by energy dispersive X-ray analysis of the joint interface including the high concentration part of the additive element is Al: additive element: O: N = 50 to 90 mass%. : 1-30 mass%: 1-10 mass%: You may be 25 mass% or less.
Further, the high concentration portion of the additive element is formed at the bonding interface with the ceramic substrate in the second metal plate, the ceramic substrate is made of Si ₃ N ₄ , and the additive element is Cu, Ag. , Zn, Mg, Ge, Ca, Ga, Li, and the junction interface including the high concentration portion of the additive element formed at the junction interface with the ceramic substrate The mass ratio of Al, Si, additive element, O, and N analyzed by energy dispersive X-ray analysis is Al: Si: additive element: O: N = 15 to 45 mass%: 15 to 45 mass%: 1 -30 mass%: 2-20 mass%: You may be 25 mass% or less.

  When the mass ratio of the additive element atoms present at the bonding interface exceeds 30% by mass, the bonding strength may be reduced by an excessive additive element. In addition, the vicinity of the bonding interface of the second metal plate is strengthened more than necessary, and stress may act on the ceramic substrate during a thermal cycle load, causing the ceramic substrate to break. On the other hand, if the mass ratio of the additive element atoms is less than 1% by mass, there is a possibility that the junction strength due to the additive element atoms cannot be sufficiently improved. Therefore, the mass ratio of the additive element atoms at the bonding interface is preferably in the range of 1 to 30% by mass.

Here, since the spot diameter at the time of performing the analysis by the energy dispersive X-ray analysis method is extremely small, measurement is performed at a plurality of points (for example, 10 to 100 points) on the bonding interface, and the average value is calculated. . When measuring, the bonding interface between the crystal grain boundary of the second metal plate and the ceramic substrate is not measured, and only the bonding interface between the crystal grain and the ceramic substrate is measured.
The analytical value obtained by the energy dispersive X-ray analysis method in this specification is the energy dispersive X-ray fluorescence element analyzer NORAN manufactured by Thermo Fisher Scientific Co., Ltd. mounted on the electron microscope JEM-2010F manufactured by JEOL. The acceleration was performed at 200 kV using System7.

Preferably, the ceramic substrate is made of AlN, and an Al ₂ O ₃ layer is formed on at least one surface of the ceramic substrate.
In this case, since the Al ₂ O ₃ layer is formed on one surface of the ceramic substrate to which the first metal plate made of copper or copper alloy is bonded, this Al ₂ O ₃ layer and the first metal plate (Copper plate) can be joined by a DBC method using a eutectic reaction between oxygen and copper. Therefore, the ceramic substrate and the first metal plate (copper plate) can be joined relatively easily and reliably.

A power module according to the present invention includes the above-described power module substrate with a heat sink and an electronic component mounted on the first metal plate.
According to the power module with a heat sink having this configuration, the heat from the electronic component mounted on the first metal plate can be efficiently dissipated, and the power density (heat generation amount) of the electronic component is improved. Even if it exists, it can respond sufficiently.

The power module substrate manufacturing method of the present invention includes a ceramic substrate, a first metal plate bonded to one surface of the ceramic substrate, and a second metal plate bonded to the other surface of the ceramic substrate. And a heat sink bonded to the other surface side of the second metal plate, and a method for manufacturing a power module substrate with a heat sink, wherein the first metal plate is made of copper or a copper alloy The second metal plate is made of aluminum having a proof stress of 30 N / mm ² or less, and the heat sink is made of a metal material having a proof strength of 100 N / mm ² or more, and the first metal plate and A copper plate joining step for joining the ceramic substrate, an aluminum plate joining step for joining the second metal plate and the ceramic substrate, and the second metal plate and the heat sink. And at least one of the aluminum plate joining step and the heat sink joining step, Si, Cu, Ag, Zn, Mg at the joining interface of the second metal plate. , Ge, Ca, Ga, Li, one or more additive elements are arranged, and the second metal plate is joined.

  According to the method for manufacturing a power module substrate having this configuration, the above-described power module substrate with a heat sink can be manufactured. Further, in at least one of the aluminum plate joining step and the heat sink joining step, Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, Li may be bonded to the joining interface of the second metal plate. Any one or two or more additional elements are arranged and the second metal plate is joined, so that the second metal plate and the ceramic substrate, or the second metal plate and the The heat sink can be firmly bonded. In addition, since elements such as Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li are elements that lower the melting point of aluminum, the bonding interface of the second metal plate can be obtained even under relatively low temperature conditions. A molten metal region can be formed. These additive elements may be fixed to the joining surface of the second metal plate or the like, or a metal foil (brazing material foil) containing these additive elements may be disposed on the joining surface.

Here, in at least one of the aluminum plate joining step and the heat sink joining step, the additive element diffuses toward the second metal plate to form a molten metal region at the joining interface. It is preferable to join by solidifying the molten metal region.
In this case, by diffusing one or more additive elements of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, Li to the second metal plate side, the first The molten metal region is formed at the bonding interface between the two metal plates, and the molten metal region is solidified to join the second metal plate by so-called diffusion bonding (Transient Liquid Phase Diffusion Bonding). Therefore, a power module substrate with a heat sink excellent in bonding reliability can be manufactured even under relatively low temperature conditions.

Moreover, it is preferable that the amount of the additive element disposed at the bonding interface of the second metal plate is in a range of 0.01 mg / cm ^{2 to} 10 mg / cm ² .
In this case, since the amount of the additional element disposed at the bonding interface of the second metal plate is 0.01 mg / cm ² or more, the molten metal region is surely formed at the bonding interface of the second metal plate. be able to.
Furthermore, since the amount of the additional element disposed at the bonding interface of the second metal plate is 10 mg / cm ² or less, the additional element is excessively diffused to the second metal plate side and the second element in the vicinity of the bonding interface. It is possible to prevent the strength of the second metal plate from becoming excessively high. Therefore, when the cooling cycle is loaded on the power module substrate, the thermal strain can be absorbed by the second metal plate, and cracking of the ceramic substrate can be prevented.
Moreover, since the amount of the additive element arranged at the bonding interface of the second metal plate is within a range of 0.01 mg / cm ² or more and 10 mg / cm ² or less, of the second metal plate It is possible to manufacture a power module substrate with a heat sink in which the total concentration of the additive elements in the vicinity of the bonding interface is in the range of 0.01% by mass to 5% by mass.

Furthermore, it is preferable to perform an alumina layer forming step of forming an Al ₂ O ₃ layer on at least one surface of the ceramic substrate before the copper plate bonding step.
In this case, by forming the Al ₂ O ₃ layer on one surface of the ceramic substrate, the first metal plate made of copper or a copper alloy and the ceramic can be bonded using the DBC method. Note that the thickness of the Al ₂ O ₃ layer to be formed is preferably 1 μm or more. This is because if the thickness of the Al ₂ O ₃ layer is less than 1 μm, the first metal plate and the ceramics may not be satisfactorily bonded.

Moreover, it is preferable to perform the said aluminum plate joining process and the said heat sink joining process simultaneously.
In this case, since the second metal plate and the ceramic substrate, and the second metal plate and the heat sink are joined at the same time, the joining step of the second metal plate can be performed once. In addition, the manufacturing cost of the power module substrate with a heat sink can be greatly reduced. Further, unnecessary thermal load does not act on the ceramic substrate, and the occurrence of warpage or the like can be suppressed. Furthermore, since the second metal plate and the heat sink are simultaneously bonded to the other surface side of the ceramic substrate, a highly rigid member is bonded to the other surface side of the ceramic substrate at one time. Generation of warpage of the ceramic substrate at the time can be suppressed.

Furthermore, it is preferable to arrange aluminum together with the additive element at the bonding interface of the second metal plate.
In this case, since aluminum is disposed together with the additive element, it is possible to reliably form a molten metal region at the bonding interface of the second metal plate. In addition, oxidation wear of the additive element can be suppressed.

Moreover, it is preferable to arrange | position the said additional element in the joining interface of said 2nd metal plate by the means selected from either vapor deposition, CVD, sputtering, plating, or application | coating of a paste.
In this case, the additive element can be reliably arranged at the bonding interface of the second metal plate by means selected from vapor deposition, CVD, sputtering, plating, or paste application.

  According to the present invention, it is possible to promote the dissipation of heat from a heating element such as an electronic component mounted on the first metal plate, and to suppress the occurrence of cracks in the ceramic substrate during a thermal cycle load. In addition, a highly reliable power module substrate with a heat sink, a power module, and a method for manufacturing a power module substrate with a heat sink can be provided.

It is a schematic explanatory drawing of the power module using the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention. It is explanatory drawing which shows the concentration distribution of the additive element of the 2nd metal plate of the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention. It is explanatory drawing which shows the density | concentration distribution of the addition element of the 2nd metal layer and heat sink (top plate part) of the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention. It is a schematic diagram of the joining interface of the 2nd metal plate of the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention, and a ceramic substrate. It is a flowchart of the manufacturing method of the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention. It is explanatory drawing which shows the manufacturing method of the board | substrate for power modules with a heat sink which is the 1st Embodiment of this invention. It is explanatory drawing which shows the joining interface vicinity of the ceramic substrate in FIG. 5, and a 2nd metal plate. It is explanatory drawing which shows the joining interface vicinity of the top-plate part in FIG. 5, and a 2nd metal plate (metal layer). It is a schematic explanatory drawing of the power module using the board | substrate for power modules with a heat sink which is the 2nd Embodiment of this invention. It is expansion explanatory drawing in the joining interface of the 1st metal plate and ceramic substrate of the board | substrate for power modules with a heat sink which is the 2nd Embodiment of this invention. It is explanatory drawing which shows the density | concentration distribution of the additive element of the 2nd metal plate of the board | substrate for power modules with a heat sink which is the 2nd Embodiment of this invention. It is explanatory drawing which shows the density | concentration distribution of the addition element of the 2nd metal layer and heat sink (top plate part) of the board | substrate for power modules with a heat sink which is the 2nd Embodiment of this invention. It is a schematic diagram of the joining interface of the 2nd metal plate and ceramic substrate of the board | substrate for power modules with a heat sink which is the 2nd Embodiment of this invention. It is a flowchart of the manufacturing method of the board | substrate for power modules with a heat sink which is embodiment of this invention. It is explanatory drawing which shows 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 of the power module using the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is explanatory drawing which shows the concentration distribution of the additive element of the 2nd metal plate of the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is explanatory drawing which shows the density | concentration distribution of the addition element of the 2nd metal layer and heat sink (top plate part) of the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is a schematic diagram of the joining interface of the 2nd metal plate and ceramic substrate of the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is a flowchart of the manufacturing method of the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is explanatory drawing which shows the manufacturing method of the board | substrate for power modules with a heat sink which is the 3rd Embodiment of this invention. It is a schematic explanatory drawing of the power module using the board | substrate for power modules with a heat sink which is other embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a power module substrate 10 with a heat sink and a power module 1 using the power module substrate 10 with a heat sink according to the first embodiment of the present invention.
The power module 1 includes a power module substrate 10 with a heat sink, and a semiconductor chip 3 (electronic component) bonded to the mounting surface 22A of the power module substrate 10 with a heat sink via a solder layer 2. Yes. Here, the solder layer 2 is made of, for example, a Sn—Ag, Sn—In, or Sn—Ag—Cu solder material. In the present embodiment, a Ni plating layer (not shown) is provided between the mounting surface 22A and the solder layer 2.

  The power module substrate 10 with a heat sink includes a ceramic substrate 21, a first metal plate 22 bonded to one surface (the upper surface in FIG. 1) of the ceramic substrate 21, and the other surface (FIG. 1). 2, a power module substrate 20, and a heat sink 11.

The ceramic substrate 21 prevents electrical connection between the first metal plate 22 and the second metal plate 23, and is made of Al ₂ O ₃ (alumina) having high insulating properties. Further, the thickness of the ceramic substrate 21 is set in a range of 0.2 to 1.5 mm, and in this embodiment, is set to 0.635 mm.

The first metal plate 22 is made of copper or a copper alloy. In the present embodiment, the first metal plate 22 is a rolled plate of tough pitch copper. Moreover, the plate | board thickness is set in the range of 0.1-1.0 mm, and is set to 0.6 mm in this embodiment.
A circuit pattern is formed on the first metal plate 22, and one surface (the upper surface in FIG. 1) is a mounting surface 22 </ b> A on which the semiconductor chip 3 is mounted.

The second metal plate 23 is made of aluminum having a proof stress of 30 N / mm ² or less. In the present embodiment, the second metal plate 23 is made of pure aluminum (so-called 4N aluminum) having a purity of 99.99% or more. Moreover, the plate | board thickness is set in the range of 0.6-6 mm, and is set to 2.0 mm in this embodiment.

The heat sink 11 is for cooling the power module substrate 20 described above. The heat sink 11 in the present embodiment includes a top plate portion 12 joined to the power module substrate 20, and a cooling member 13 stacked on the top plate portion 12. Inside the cooling member 13, a flow path 14 through which a cooling medium flows is formed.
Here, the top plate 12 and the cooling member 13 are connected by a fixing screw 15. For this reason, it is necessary to ensure rigidity so that the top plate portion 12 is not easily deformed even if the fixing screw 15 is screwed. Therefore, in this embodiment, the top plate portion 12 of the heat sink 11 is made of a metal material having a proof stress of 100 N / mm ² or more, and the thickness thereof is 2 mm or more. In the present embodiment, the top plate 12 is made of an A6063 alloy (aluminum alloy).

As shown in FIG. 2, at the bonding interface 30 between the ceramic substrate 21 and the second metal plate 23, any one of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li is used. The seed or two or more additive elements are in solid solution, and in this embodiment, Cu is dissolved as the additive element.
Here, in the vicinity of the bonding interface 30 of the second metal plate 23, a concentration gradient layer 31 is formed in which the concentration of the additive element (Cu concentration in this embodiment) gradually decreases as the distance from the bonding interface 30 in the stacking direction is increased. Has been. In addition, the concentration of the additive element (Cu concentration in the present embodiment) on the bonding interface 30 side (near the bonding interface 30 of the second metal plate 23) of the concentration gradient layer 31 is 0.01% by mass or more and 5% by mass or less. It is set within the range.
The concentration of the additive element in the vicinity of the bonding interface 30 of the second metal plate 23 is an average value measured at five points from the bonding interface 30 by an EPMA analysis (spot diameter of 30 μm). The graph of FIG. 2 is obtained by performing line analysis in the stacking direction at the central portion of the second metal plate 23 and using the concentration at the above-mentioned 50 μm position as a reference.

Further, as shown in FIG. 3, at the bonding interface 40 between the second metal plate 23 and the top plate portion 12 of the heat sink 11, the second metal plate 23 and the top plate portion 12 have Si, Cu, Ag, Any one or two or more additive elements of Zn, Mg, Ge, Ca, Ga, and Li are in solid solution, and in this embodiment, Cu is in solution as the additive element.
Here, in the vicinity of the bonding interface 40 between the second metal plate 23 and the top plate portion 12, the concentration of the additive element (Cu concentration in this embodiment) gradually decreases as the distance from the bonding interface 40 in the stacking direction is increased. Inclined layers 41 and 42 are formed. In addition, the concentration (Cu concentration in the present embodiment) of the additive element on the side of the bonding interface 40 of the concentration gradient layers 41 and 42 (near the bonding interface 40 of the second metal plate 23 and the top plate 12) is 0.01. It is set within a range of mass% to 5 mass%.
The concentration of the additive element in the vicinity of the bonding interface 40 between the second metal plate 23 and the top plate 12 is an average value measured at 50 points from the bonding interface 40 by EPMA analysis (spot diameter 30 μm). is there. Further, the graph of FIG. 3 is obtained by performing line analysis in the stacking direction in the central portion of the second metal plate 23 and the top plate portion 12 and obtaining the above-described concentration at the 50 μm position as a reference.

  In addition, when the bonding interface 30 between the ceramic substrate 21 and the second metal plate 23 is observed with a transmission electron microscope, as shown in FIG. A density portion 32 is formed. In the additive element high concentration portion 32, the additive element concentration (Cu concentration) is set to be twice or more the additive element concentration (Cu concentration) in the second metal plate 23. The thickness H of the additive element high concentration portion 32 is 4 nm or less.

  Note that the bonding interface 30 observed here has a reference plane S at the center between the interface side end of the lattice image of the second metal plate 23 and the end of the lattice image of the ceramic substrate 21. . The concentration (Cu concentration) of the additive element in the second metal plate 23 is the concentration of the additive element in the portion of the second metal plate 23 that is away from the bonding interface 30 by a certain distance (5 nm in this embodiment) ( Cu concentration).

  The mass ratio of Al, additive element (Cu), and O when this bonding interface 30 is analyzed by energy dispersive X-ray analysis (EDS) is Al: additive element (Cu): O = 50 to 90 mass. %: 1 to 30% by mass: set within a range of 45% by mass or less. In addition, the spot diameter at the time of performing the analysis by EDS is 1 to 4 nm, the bonding interface 30 is measured at a plurality of points (for example, 20 points in the present embodiment), and the average value is calculated. Further, the bonding interface 30 between the crystal grain boundary of the second metal plate 23 and the ceramic substrate 21 is not measured, and only the bonding interface 30 between the crystal grain of the second metal plate 23 and the ceramic substrate 21 is measured. Yes. Analytical values obtained by energy dispersive X-ray analysis are accelerated using an energy dispersive X-ray fluorescence element analyzer NORAN System 7 manufactured by Thermo Fisher Scientific Co., Ltd. mounted on an electron microscope JEM-10F manufactured by JEOL. The voltage was 200 kV.

  Below, the manufacturing method of the board | substrate 10 for power modules with a heat sink of the above-mentioned structure is demonstrated with reference to FIGS.

First, as shown in FIGS. 5 and 6, the first metal plate 22 made of copper and the ceramic substrate 21 are joined (copper plate joining step S01). Here, since the ceramic substrate 21 is made of Al ₂ O ₃ , the first metal plate 22 made of copper and the ceramic substrate 21 are joined by a DBC method using a eutectic reaction between copper and oxygen. . Specifically, the first metal plate 22 made of tough pitch copper and the ceramic substrate 21 are brought into contact with each other and heated at 1075 ° C. for 10 minutes in a nitrogen gas atmosphere. 21 will be joined.

  Next, the second metal plate 23 is joined to the other surface side of the ceramic substrate 21 (aluminum plate joining step S02), and the second metal plate 23 and the top plate portion 12 of the heat sink 11 are joined (heat sink). Joining step S03). In this embodiment, the aluminum plate joining step S02 and the heat sink joining step S03 are performed simultaneously.

The additive element (Cu) is fixed to the joint surface of the second metal plate 23 with the ceramic substrate 21 by sputtering to form the first fixed layer 51, and the top plate portion 12 of the heat sink 11 of the second metal plate 23. Then, an additional element (Cu) is fixed to the joint surface by sputtering to form the second fixed layer 52 (fixed layer forming step S11). Here, the amount of added elements in the first fixed layer 51 and the second fixed layer 52 is in the range of 0.01 mg / cm ² or more and 10 mg / cm ² or less, and in this embodiment, Cu is used as the additive element. The amount of Cu in the first fixing layer 51 and the second fixing layer 52 is set to 0.08 mg / cm ² or more and 2.7 mg / cm ² or less.

Next, as shown in FIG. 6, the second metal plate 23 is laminated on the other surface side of the ceramic substrate 21. Furthermore, the top plate portion 12 of the heat sink 11 is laminated on the other surface side of the second metal plate 23 (lamination step S12).
At this time, as shown in FIG. 6, the surface of the second metal plate 23 on which the first fixing layer 51 is formed faces the ceramic substrate 21, and the second fixing layer 52 of the second metal plate 23. These are laminated so that the surface on which the is formed faces the top plate 12. That is, the first fixing layer 51 (additive element: Cu) is interposed between the second metal plate 23 and the ceramic substrate 21, and the second fixing layer is interposed between the second metal plate 23 and the top plate portion 12. 52 (additive element: Cu) is interposed.

Next, the first metal plate 22, the ceramic substrate 21, the second metal plate 23, and the top plate part 12 are loaded in a vacuum heating furnace in a state of being pressurized (pressure 1 to 35 kgf / cm ² ) in the stacking direction. And heated (heating step S13). Here, in this embodiment, the pressure in a vacuum heating furnace is set in the range of 10 < ^-3 > -10 < ^-6 > Pa, and the heating temperature is set in the range of 550 degreeC or more and 650 degrees C or less.

Then, as shown in FIG. 7, the first molten metal region 55 is formed at the interface between the second metal plate 23 and the ceramic substrate 21. As shown in FIG. 7, the first molten metal region 55 has a first element of the second metal plate 23 as a result of the additive element (Cu) of the first fixed layer 51 diffusing to the second metal plate 23 side. It is formed by increasing the concentration (Cu concentration) of the additive element in the vicinity of the fixed layer 51 and lowering the melting point.
Further, as shown in FIG. 8, a second molten metal region 56 is formed at the interface between the second metal plate 23 and the top plate portion 12. As shown in FIG. 8, the second molten metal region 56 has a second element (Cu) diffused to the second metal plate 23 side and the top plate part 12 side as a result of the second fixed layer 52 being diffused. It is formed by increasing the concentration (Cu concentration) of the additive element in the vicinity of the second fixed layer 52 of the metal plate 23 and the top plate portion 12 and lowering the melting point.

Next, the temperature is kept constant with the first molten metal region 55 and the second molten metal region 56 formed (molten metal solidification step S14).
Then, Cu in the 1st molten metal area | region 55 will spread | diffuse further to the 2nd metal plate 23 side. As a result, the Cu concentration in the portion that was the first molten metal region 55 gradually decreases and the melting point increases, and solidification proceeds while the temperature is kept constant. Thereby, the ceramic substrate 21 and the second metal plate 23 are joined.
Similarly, Cu in the second molten metal region 56 further diffuses toward the second metal plate 23 side and the top plate portion 12 side, and the Cu concentration in the portion that was the second molten metal region 56 gradually decreases. As a result, the melting point rises, and solidification proceeds with the temperature kept constant. Thereby, the 2nd metal plate 23 and the top-plate part 12 are joined.

  That is, the ceramic substrate 21 and the second metal plate 23, and the top plate portion 12 and the second metal plate 23 are joined by so-called diffusion bonding (Transient Liquid Phase Diffusion Bonding). After solidification progresses in this way, cooling is performed to room temperature.

  In this way, the first metal plate 22, the ceramic substrate 21, the second metal plate 23, and the top plate portion 12 of the heat sink 11 are joined, and the power module substrate 10 with a heat sink according to this embodiment is manufactured. Will be.

  According to the power module substrate with a heat sink 10 of the present embodiment configured as described above, the first metal plate 22 having the mounting surface 22A on which the semiconductor chip 3 is mounted is made of tough pitch copper. Therefore, the heat generated from the semiconductor chip 3 can be sufficiently expanded, and the dissipation of this heat can be promoted. Therefore, electronic parts such as the semiconductor chip 3 having a high power density can be mounted, and the semiconductor package can be reduced in size and output.

Further, the top plate portion 12 of the heat sink 11 is made of a metal material having a proof stress of 100 N / mm ² or more and has a thickness of 2 mm or more. In this embodiment, the top plate portion 12 is made of an A6063 alloy (aluminum alloy). Therefore, it is highly rigid and easy to handle. Therefore, as shown in FIG. 1, this top plate part 12 can be fixed to the cooling member 13 with the fixing screw 15, and it becomes possible to comprise the heat sink 11 excellent in cooling capability.

Furthermore, a second metal plate made of aluminum having a proof stress of 30 N / mm ² or less (in this embodiment, pure aluminum having a purity of 99.99% or more) between the top plate portion 12 of the heat sink 11 and the ceramic substrate 21. 23 is provided, even if the top plate portion 12 of the heat sink 11 has a high rigidity, the second thermal strain caused by the difference in thermal expansion coefficient between the top plate portion 12 of the heat sink 11 and the ceramic substrate 21 is reduced. The metal plate 23 can sufficiently relax, and the occurrence of cracks in the ceramic substrate 21 can be suppressed. In particular, in the present embodiment, since the thickness of the second metal layer is in the range of 0.6 to 6 mm, it is possible to absorb the thermal strain with certainty and the heat generated by the second metal plate 23. An increase in resistance can be suppressed.

In the present embodiment, since the ceramic substrate 21 is made of Al ₂ O ₃ , as described above, the first metal plate 22 made of tough pitch copper and the ceramic substrate 21 are combined with oxygen and copper. Bonding can be performed by a DBC method using a crystal reaction. Therefore, the bonding strength between the ceramic substrate 21 and the first metal plate 22 can be ensured, and the power module substrate 10 with a heat sink excellent in bonding reliability can be configured.

  Further, the bonding interface 30 between the second metal plate 23 and the ceramic substrate 21 and the bonding interface 40 between the second metal plate 23 and the top plate portion 12 of the heat sink 11 have Si, Cu, Ag, Zn, One or more additive elements of Mg, Ge, Ca, Ga, and Li are in solid solution, and in this embodiment, Cu is dissolved as the additive element. The joint interfaces 30 and 40 side portions of the metal plate 23 are strengthened by solid solution, and breakage at the second metal plate 23 portion can be prevented.

  Here, since the concentration of the additive element (Cu concentration in the present embodiment) in the vicinity of the bonding interfaces 30 and 40 in the second metal plate 23 is set within a range of 0.01% by mass to 5% by mass. The strength in the vicinity of the bonding interfaces 30 and 40 of the second metal plate 23 can be prevented from becoming excessively high, and when the cooling module is loaded on the power module substrate 10 with heat sink, It becomes possible to relieve with the metal plate 23, and the generation | occurrence | production of the crack of the ceramic substrate 21 can be suppressed.

  In addition, one or more of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li are added to the bonding interface 30 between the second metal plate 23 and the ceramic substrate 21. Since the element concentration (Cu concentration in the present embodiment) is higher than the concentration of the additive element in the second metal plate 23, the additive element high concentration portion 32 is formed. It is possible to improve the bonding strength of the second metal plate 23 by the additive element atoms (Cu atoms) to be performed.

  Further, the mass ratio of Al, additive element (Cu), and O obtained by analyzing the bonding interface 30 including the high concentration element 32 by energy dispersive X-ray analysis is Al: additive element (Cu): O = 50˜ Since 90 mass%: 1-30 mass%: 45 mass% or less, the reaction product of Al and the additive element (Cu) is not generated excessively, and the second metal plate 23 and the ceramic substrate 21 can be favorably bonded. Moreover, the vicinity of the bonding interface 30 of the second metal plate 23 is not strengthened more than necessary by the reactant, and it becomes possible to absorb the thermal strain with certainty, and the ceramic substrate 21 is cracked under a heat cycle load. Can be suppressed.

According to the method for manufacturing the power module substrate with heat sink 10 of the present embodiment, the power module substrate with heat sink 10 described above can be manufactured. In addition, in the aluminum plate joining step S02 and the heat sink joining step S03, any one of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li is formed on the joining interfaces 30 and 40 of the second metal plate 23. Since one or more additive elements (Cu in this embodiment) are arranged and the second metal plate 23 is joined, the second metal plate 23, the ceramic substrate 21, and the second metal plate 23 are used. The metal plate 23 and the top plate portion 12 of the heat sink 11 can be firmly joined to each other. Further, since elements such as Si, Cu, Zn, Mg, Ge, Ca, and Li are elements that lower the melting point of aluminum, the bonding interfaces 30 and 40 of the second metal plate 23 even under relatively low temperature conditions. In addition, the first molten metal region 55 and the second molten metal region 56 can be formed.
Further, it is presumed that the vicinity of the bonding interfaces 30 and 40 is activated by the presence of Cu, and the ceramic substrate 21 and the second metal plate 23, and the top plate portion 12 and the second metal plate 23 are respectively connected even under a low temperature condition. It becomes possible to join firmly.

  In the present embodiment, in the aluminum plate joining step S02 and the heat sink joining step S03, the additive element (Cu) diffuses toward the second metal plate 23 side and the top plate portion 12 side, thereby joining the interface 30. 40, a first molten metal region 55 and a second molten metal region 56 are formed, and the first molten metal region 55 and the second molten metal region 56 are joined by solidification, so-called diffusion bonding (Transient Liquid Phase Diffusion). Since bonding is performed by Bonding), the power module substrate 10 with a heat sink can be manufactured, which can be firmly bonded under relatively low temperature conditions and has excellent bonding reliability.

In addition, the amount of additive elements in the first fixed layer 51 and the second fixed layer 52 formed on the bonding surface of the second metal plate 23 is in the range of 0.01 mg / cm ^{2 to} 10 mg / cm ^2. In this embodiment, Cu is used as the additive element, and the amount of Cu in the first fixed layer 51 and the second fixed layer 52 is set to 0.08 mg / cm ² or more and 2.7 mg / cm ² or less. The first molten metal region 55 and the second molten metal region 56 can be reliably formed at the bonding interfaces 30 and 40 of the second metal plate 23. Further, it is possible to prevent the additive element (Cu) from excessively diffusing to the second metal plate 23 side and excessively increasing the strength of the second metal plate 23 in the vicinity of the bonding interfaces 30 and 40. Therefore, when a heat cycle is applied to the power module substrate 10 with a heat sink, the thermal strain can be reliably absorbed by the second metal plate 23, and cracking of the ceramic substrate 21 can be prevented.

Moreover, in this embodiment, since it is set as the structure which performs aluminum plate joining process S02 and heat sink joining process S03 simultaneously, the joining process of both surfaces of the 2nd metal plate 23 can be performed at once, and this power supply with a heat sink can be performed. The manufacturing cost of the module substrate 10 can be greatly reduced. Furthermore, unnecessary thermal load does not act on the ceramic substrate 21, and the occurrence of warpage or the like can be suppressed.
Further, since the first fixed layer 51 and the second fixed layer 52 are formed by fixing the additive element (Cu) to the joint surface of the second metal plate 23 by sputtering, the second metal plate 23 is formed. It is possible to reliably arrange the additive element at the bonding interfaces 30 and 40.

Next, a second embodiment of the present invention will be described with reference to FIGS.
A power module 101 shown in FIG. 9 includes a power module substrate 110 with a heat sink, and a semiconductor chip 3 (electronic component) bonded to the mounting surface 122A of the power module substrate 110 with a heat sink via a solder layer 2. It has. Here, the solder layer 2 is made of, for example, a Sn—Ag, Sn—In, or Sn—Ag—Cu solder material. In the present embodiment, a Ni plating layer (not shown) is provided between the mounting surface 122A and the solder layer 2.

  The power module substrate 110 with a heat sink includes a ceramic substrate 121, a first metal plate 122 bonded to one surface (upper surface in FIG. 9) of the ceramic substrate 121, and the other surface of the ceramic substrate 121 (FIG. 9). , A power module substrate 120 and a heat sink 111 are provided.

  The ceramic substrate 121 prevents electrical connection between the first metal plate 122 and the second metal plate 123, and is made of highly insulating AlN (aluminum nitride). Further, the thickness of the ceramic substrate 121 is set within a range of 0.2 to 1.5 mm, and is set to 0.635 mm in the present embodiment.

The first metal plate 122 is made of copper or a copper alloy. In the present embodiment, the first metal plate 122 is a rolled plate of tough pitch copper. Moreover, the plate | board thickness is set in the range of 0.1-1.0 mm, and is set to 0.6 mm in this embodiment.
A circuit pattern is formed on the first metal plate 122, and one surface (the upper surface in FIG. 9) is a mounting surface 122A on which the semiconductor chip 3 is mounted.

Here, an Al ₂ O ₃ layer 125 is formed at the interface between the ceramic substrate 121 and the first metal plate 122 as shown in FIG. In the present embodiment, the thickness of the Al ₂ O ₃ layer 125 is 1 μm or more.

The second metal plate 123 is made of aluminum having a proof stress of 30 N / mm ² or less, and is made of pure aluminum (so-called 4N aluminum) having a purity of 99.99% or more in this embodiment. Moreover, the plate | board thickness is set in the range of 0.6-6 mm, and is set to 2.0 mm in this embodiment.

The heat sink 111 is for cooling the power module substrate 120 described above. The heat sink 111 in the present embodiment includes a top plate portion 112 joined to the power module substrate 120 and a flow path 114 for circulating a cooling medium (for example, cooling water).
Here, the heat sink 111 (top plate portion 112) is preferably made of a material having good thermal conductivity, and it is necessary to ensure rigidity as a structural material. Therefore, in the present embodiment, the top plate portion 112 of the heat sink 111 is made of A6063 (aluminum alloy).

As shown in FIG. 11, at the bonding interface 130 between the ceramic substrate 121 and the second metal plate 123, any one of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li is used. The seed or two or more additional elements are in solid solution, and in this embodiment, Ge is dissolved in the additive element.
Here, in the vicinity of the bonding interface 130 of the second metal plate 123, a concentration gradient layer 131 in which the concentration of the additive element (Ge concentration in the present embodiment) gradually decreases as the distance from the bonding interface 130 in the stacking direction is formed. Has been. In addition, the concentration of the additive element (Ge concentration in the present embodiment) on the bonding interface 130 side (near the bonding interface 130 of the second metal plate 123) of the concentration gradient layer 131 is 0.01 mass% or more and 5 mass% or less. It is set within the range.
The concentration of the additive element in the vicinity of the bonding interface 130 of the second metal plate 123 is an average value measured at 5 points from the bonding interface 130 by EPMA analysis (spot diameter 30 μm). Further, the graph of FIG. 11 is obtained by performing line analysis in the stacking direction in the central portion of the second metal plate 123 and obtaining the above-described concentration at the 50 μm position as a reference.

As shown in FIG. 12, at the bonding interface 140 between the second metal plate 123 and the top plate portion 112 of the heat sink 111, the second metal plate 123 and the top plate portion 112 have Si, Cu, Ag, Any one or more additive elements of Zn, Mg, Ge, Ca, Ga, and Li are in solid solution. In this embodiment, Ge is in solution as the additive element.
Here, in the vicinity of the bonding interface 140 between the second metal plate 123 and the top plate portion 112, the concentration of the additive element (Ge concentration in this embodiment) gradually decreases as the distance from the bonding interface 140 in the stacking direction is increased. Inclined layers 141 and 142 are formed. In addition, the concentration of the additive element (Ge concentration in the present embodiment) on the side of the bonding interface 140 of the concentration gradient layers 141 and 142 (near the bonding interface 140 of the second metal plate 123 and the top plate portion 112) is 0.01. It is set within a range of mass% to 5 mass%.
The concentration of the additive element in the vicinity of the bonding interface 140 of the second metal plate 123 and the top plate portion 112 is an average value measured at 5 points from the bonding interface 140 by EPMA analysis (spot diameter 30 μm). is there. In addition, the graph of FIG. 12 is obtained by performing line analysis in the stacking direction in the central portion of the second metal plate 123 and the top plate portion 112 and obtaining the concentration at the above-described 50 μm position as a reference.

  In addition, when the bonding interface 130 between the ceramic substrate 121 and the second metal plate 123 is observed with a transmission electron microscope, as shown in FIG. A density portion 132 is formed. In the additive element high concentration portion 132, the additive element concentration (Ge concentration) is set to be twice or more the additive element concentration (Ge concentration) in the second metal plate 123. The thickness H of the additive element high concentration portion 132 is 4 nm or less.

  Note that, as shown in FIG. 13, the bonding interface 130 observed here is between the interface side end of the lattice image of the second metal plate 123 and the end of the lattice image of the ceramic substrate 121 on the side of the bonding interface 130. The center is defined as a reference plane S. In addition, the concentration of the additive element (Ge concentration) in the second metal plate 123 is the concentration of the additive element in the portion of the second metal plate 123 that is away from the bonding interface 130 by a certain distance (5 nm in this embodiment) ( Ge concentration).

The mass ratio of Al, additive element (Ge), O, and N when this bonding interface 130 is analyzed by energy dispersive X-ray analysis (EDS) is Al: additive element (Ge): O: N = It is set in the range of 50 to 90% by mass: 1 to 30% by mass: 1 to 10% by mass: 25% by mass or less. In addition, the spot diameter at the time of performing the analysis by EDS is 1 to 4 nm, the bonding interface 130 is measured at a plurality of points (for example, 20 points in the present embodiment), and the average value is calculated. Further, the bonding interface 130 between the crystal grain boundary of the second metal plate 123 and the ceramic substrate 121 is not measured, and only the bonding interface 130 between the crystal grain of the second metal plate 123 and the ceramic substrate 121 is measured. Yes.
Analyzed values by energy dispersive X-ray analysis are accelerated using an energy dispersive X-ray fluorescence element analyzer NORAN System 7 manufactured by Thermo Fisher Scientific Co., Ltd. mounted on an electron microscope JEM-2010F manufactured by JEOL. The voltage was 200 kV.

  Below, the manufacturing method of the board | substrate 110 for power modules with a heat sink of the above-mentioned structure is demonstrated.

First, as shown in FIGS. 14 and 15, an Al ₂ O ₃ layer 125 is formed on one surface of a ceramic substrate 121 made of AlN (alumina layer forming step S100). In this alumina layer forming step S100, the oxidation treatment of AlN was performed at 1200 ° C. or higher in an Ar—O ₂ mixed gas atmosphere. The oxygen partial pressure _{P O2} and 10 kPa, to prepare a water vapor partial pressure _{P H2 O} to 0.05 kPa. As described above, by performing the oxidation treatment of AlN in a high oxygen partial pressure / low water vapor partial pressure atmosphere, a dense Al ₂ O ₃ layer 125 having excellent adhesion to AlN is formed. Here, the thickness of the Al ₂ O ₃ layer 125 is 1 μm or more.
In addition, oxygen partial pressure was adjusted by mixing oxygen gas after deoxidizing high purity Ar gas. Moreover, after performing dehydration treatment by passing this atmospheric gas through a drying system filled with silica gel and diphosphorus pentoxide, the water vapor partial pressure was adjusted by passing water adjusted to a predetermined temperature.

Next, the first metal plate 122 made of copper and the ceramic substrate 121 are bonded (copper plate bonding step S101). Here, since the Al ₂ O ₃ layer 125 is formed on one surface of the ceramic substrate 121 made of AlN, the first metal plate 122 made of copper and the Al ₂ O ₃ layer 125 are made of copper and oxygen. Joining is performed by the DBC method using the eutectic reaction. Specifically, the first metal plate 122 made of tough pitch copper and the Al ₂ O ₃ layer 125 of the ceramic substrate 121 are brought into contact with each other and heated at 1075 ° C. for 10 minutes in a nitrogen gas atmosphere. The metal plate 122 and the Al ₂ O ₃ layer 125 of the ceramic substrate 121 are joined.

  Next, the second metal plate 123 is joined to the other surface side of the ceramic substrate 121 (aluminum plate joining step S102), and the second metal plate 123 and the heat sink 111 (top plate portion 112) are joined ( Heat sink joining step S103). In the present embodiment, the aluminum plate joining step S102 and the heat sink joining step S103 are performed simultaneously.

An additive element is fixed to the bonding surface of the second metal plate 123 with the ceramic substrate 121 by sputtering to form the first fixed layer 151, and the second metal plate 123 is connected to the heat sink 111 (top plate portion 112) of the second metal plate 123. An additional element is fixed to the bonding surface by sputtering to form the second fixed layer 152 (fixed layer forming step S111). Here, the amount of added elements in the first fixed layer 151 and the second fixed layer 152 is in the range of 0.01 mg / cm ^{2 to} 10 mg / cm ² , and in this embodiment, Ge is used as the additive element. The Ge amount in the first fixed layer 151 and the second fixed layer 152 is set to 0.01 mg / cm ² or more and 10 mg / cm ² or less.

Next, as shown in FIG. 15, the second metal plate 123 is laminated on the other surface side of the ceramic substrate 121. Further, the top plate portion 112 of the heat sink 111 is laminated on the other surface side of the second metal plate 123 (lamination step S112).
At this time, as shown in FIG. 15, the surface of the second metal plate 123 on which the first fixing layer 151 is formed faces the ceramic substrate 121, and the second fixing layer 152 of the second metal plate 123. These are laminated so that the surface on which the is formed faces the top plate portion 112. That is, the first fixing layer 151 (additive element: Ge) is interposed between the second metal plate 123 and the ceramic substrate 121, and the second fixing layer is interposed between the second metal plate 123 and the top plate portion 112. 152 (additive element: Ge) is interposed.

Next, the first metal plate 122, the ceramic substrate 121, the second metal plate 123, and the top plate portion 112 are pressed in the stacking direction (pressure 1 to 35 kgf / cm ² ) in a vacuum heating furnace. And heated (heating step S113). Here, in this embodiment, the pressure in the vacuum heating furnace is set in a range of 10 ⁻³ to 10 ⁻⁶ Pa, and the heating temperature is set in a range of 550 ° C. or more and 650 ° C. or less.

As a result, a first molten metal region is formed at the interface between the second metal plate 123 and the ceramic substrate 121. In the first molten metal region, the additive element (Ge) of the first fixed layer 151 diffuses to the second metal plate 123 side, so that the additive element in the vicinity of the first fixed layer 151 of the second metal plate 123 It is formed by increasing the concentration (Ge concentration) and lowering the melting point.
Further, a second molten metal region is formed at the interface between the second metal plate 123 and the top plate portion 112. In the second molten metal region, the additive element (Ge) of the second fixed layer 152 is diffused to the second metal plate 123 side and the top plate portion 112 side, whereby the second metal plate 123 and the top plate portion 112. This is formed by increasing the concentration (Ge concentration) of the additive element in the vicinity of the second fixed layer 152 and lowering the melting point.

Next, the temperature is kept constant with the first molten metal region and the second molten metal region formed (molten metal solidification step S114).
Then, Ge in the first molten metal region is further diffused toward the second metal plate 123 side. As a result, the Ge concentration in the portion that was the first molten metal region gradually decreases and the melting point increases, and solidification proceeds while the temperature is kept constant. Thereby, the ceramic substrate 121 and the second metal plate 123 are joined.
Similarly, Ge in the second molten metal region further diffuses toward the second metal plate 123 side and the top plate portion 112 side, and the Ge concentration in the portion that was the second molten metal region gradually decreases. The melting point will rise, and solidification will proceed with the temperature kept constant. Thereby, the 2nd metal plate 123 and the top-plate part 112 are joined.

  That is, the ceramic substrate 121 and the second metal plate 123, and the top plate portion 112 and the second metal plate 123 are joined by so-called diffusion bonding (Transient Liquid Phase Diffusing Bonding). After solidification progresses in this way, cooling is performed to room temperature.

  In this way, the first metal plate 122, the ceramic substrate 121, the second metal plate 123, and the heat sink 111 (the top plate portion 112) are joined, and the power module substrate 110 with a heat sink according to this embodiment is manufactured. Will be.

  According to the power module substrate with heat sink 110 of the present embodiment configured as described above, the same operational effects as the power module substrate with heat sink of the first embodiment described above are obtained, Heat from a heating element such as the semiconductor chip 3 mounted on the first metal plate 122 can be efficiently promoted, and the generation of cracks in the ceramic substrate 121 during a heat cycle load can be suppressed and It is possible to provide a power module substrate 110 with a heat sink having high performance.

In the present embodiment, an Al ₂ O ₃ layer 125 is formed on one surface of the ceramic substrate 121 made of AlN, and the first metal plate 122 made of copper is connected to the Al ₂ O ₃ layer 125 via the Al ₂ O ₃ layer 125. Since the ceramic substrate 121 is joined by the DBC method, the first metal plate 122 and the ceramic substrate 121 can be firmly joined. Therefore, even if the ceramic substrate 121 is made of AlN, the first metal plate 122 made of copper can be bonded using the DBC method.

Furthermore, since the thickness of the Al ₂ O ₃ layer 125 to be formed is 1 μm or more in the alumina layer forming step S100, the first metal plate 122 and the ceramic substrate 121 can be reliably bonded.
In the present embodiment, since the AlN is oxidized in a high oxygen partial pressure / low steam partial pressure atmosphere, the dense Al ₂ O ₃ layer 125 having excellent adhesion to AlN is formed. Further, it is possible to prevent the occurrence of peeling between the ceramic substrate 121 made of AlN and the Al ₂ O ₃ layer 125.

Next, a third embodiment of the present invention will be described with reference to FIGS.
A power module 201 shown in FIG. 16 includes a power module substrate 210 with a heat sink, and a semiconductor chip 3 (electronic component) bonded to the mounting surface 222A of the power module substrate 210 with a heat sink via a solder layer 2. It has. Here, the solder layer 2 is made of, for example, a Sn—Ag, Sn—In, or Sn—Ag—Cu solder material. In the present embodiment, a Ni plating layer (not shown) is provided between the mounting surface 222A and the solder layer 2.

  The power module substrate 210 with a heat sink includes a ceramic substrate 221, a first metal plate 222 bonded to one surface (upper surface in FIG. 16) of the ceramic substrate 221, and the other surface of the ceramic substrate 221 (FIG. 16). The power module substrate 220 including the second metal plate 223 bonded to the lower surface in FIG.

The ceramic substrate 221 prevents electrical connection between the first metal plate 222 and the second metal plate 223, and is made of highly insulating Si ₃ N ₄ (silicon nitride). . Further, the thickness of the ceramic substrate 221 is set within a range of 0.2 to 1.5 mm, and in this embodiment, is set to 0.32 mm.

The first metal plate 222 is made of copper or a copper alloy, and is a tough pitch copper rolled plate in the present embodiment. Moreover, the plate | board thickness is set in the range of 0.1-1.0 mm, and is set to 0.6 mm in this embodiment.
A circuit pattern is formed on the first metal plate 222, and one surface (the upper surface in FIG. 16) is a mounting surface 222A on which the semiconductor chip 3 is mounted.

The second metal plate 223 is made of aluminum having a proof stress of 30 N / mm ² or less, and is made of pure aluminum (so-called 4N aluminum) having a purity of 99.99% or more in this embodiment. Moreover, the plate | board thickness is set in the range of 0.6-6 mm, and is set to 2.0 mm in this embodiment.

The heat sink 211 is for cooling the power module substrate 220 described above. The heat sink 211 in this embodiment includes a top plate portion 212 joined to the power module substrate 220 and a flow path 214 for circulating a cooling medium (for example, cooling water).
Here, it is desirable that the heat sink 211 (top plate portion 212) be made of a material having good thermal conductivity, and it is necessary to ensure rigidity as a structural material. Therefore, in the present embodiment, the top plate portion 212 of the heat sink 211 is made of A6063 (aluminum alloy).

As shown in FIG. 17, at the bonding interface 230 between the ceramic substrate 221 and the second metal plate 223, any one of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li is used. The seed or two or more additive elements are in solid solution, and in this embodiment, Cu is dissolved as the additive element.
Here, in the vicinity of the bonding interface 230 of the second metal plate 223, a concentration gradient layer 231 in which the concentration of the additive element (Cu concentration in the present embodiment) gradually decreases as the distance from the bonding interface 230 in the stacking direction is formed. Has been. In addition, the concentration of the additive element (Cu concentration in the present embodiment) on the bonding interface 230 side (near the bonding interface 230 of the second metal plate 223) of the concentration gradient layer 231 is 0.01 mass% or more and 5 mass% or less. It is set within the range.
The concentration of the additive element in the vicinity of the bonding interface 230 of the second metal plate 223 is an average value measured at five points from the bonding interface 230 by the EPMA analysis (spot diameter of 30 μm). Further, the graph of FIG. 17 is obtained by performing line analysis in the stacking direction in the central portion of the second metal plate 223 and using the concentration at the above-described 50 μm position as a reference.

As shown in FIG. 18, at the bonding interface 240 between the second metal plate 223 and the top plate portion 212 of the heat sink 211, the second metal plate 223 and the top plate portion 212 have Si, Cu, Ag, Any one or two or more additive elements of Zn, Mg, Ge, Ca, Ga, and Li are in solid solution, and in this embodiment, Cu is in solution as the additive element.
Here, in the vicinity of the bonding interface 240 between the second metal plate 223 and the top plate portion 212, the concentration of the additive element (Cu concentration in this embodiment) gradually decreases as the distance from the bonding interface 240 in the stacking direction is increased. Inclined layers 241 and 242 are formed. Further, the concentration of the additive element (the Cu concentration in the present embodiment) on the side of the bonding interface 240 of the concentration gradient layers 241 and 242 (near the bonding interface 240 of the second metal plate 223 and the top plate portion 212) is 0.01. It is set within a range of mass% to 5 mass%.
The concentration of the additive element in the vicinity of the bonding interface 240 of the second metal plate 223 and the top plate portion 212 is an average value measured at 5 points from the bonding interface 240 by EPMA analysis (spot diameter 30 μm). is there. Further, the graph of FIG. 12 is obtained by performing line analysis in the stacking direction in the central portion of the second metal plate 223 and the top plate portion 212 and obtaining the above-described concentration at the 50 μm position as a reference.

  In addition, when the bonding interface 230 between the ceramic substrate 221 and the second metal plate 223 is observed with a transmission electron microscope, as shown in FIG. A density portion 232 is formed. In the additive element high concentration portion 232, the additive element concentration (Cu concentration) is set to be twice or more the additive element concentration (Si concentration) in the second metal plate 223. The thickness H of the additive element high concentration portion 232 is 4 nm or less.

  As shown in FIG. 19, the bonding interface 230 observed here is between the interface side end of the lattice image of the second metal plate 223 and the end of the lattice image of the ceramic substrate 221 on the side of the bonding interface 230. Let the center be a reference plane S. Further, the concentration of the additive element (Cu concentration) in the second metal plate 223 is the concentration of the additive element in the portion of the second metal plate 223 that is away from the bonding interface 230 by a certain distance (5 nm in this embodiment) ( Cu concentration).

The mass ratio of Al, Si, additive element (Cu), O, and N when the bonding interface 230 is analyzed by energy dispersive X-ray analysis (EDS) is Al: Si: additive element (Cu): O: N = 15 to 45% by mass: 15 to 45% by mass: 1 to 30% by mass: 2 to 20% by mass: 25% by mass or less. In addition, the spot diameter at the time of performing the analysis by EDS is 1 to 4 nm, the bonding interface 230 is measured at a plurality of points (for example, 20 points in the present embodiment), and the average value is calculated. Further, the bonding interface 230 between the crystal grain boundary of the second metal plate 223 and the ceramic substrate 121 is not measured, and only the bonding interface 230 between the crystal grain of the second metal plate 223 and the ceramic substrate 221 is measured. Yes.
Analyzed values by energy dispersive X-ray analysis are accelerated using an energy dispersive X-ray fluorescence element analyzer NORAN System 7 manufactured by Thermo Fisher Scientific Co., Ltd. mounted on an electron microscope JEM-2010F manufactured by JEOL. The voltage was 200 kV.

  Below, the manufacturing method of the board | substrate 210 for power modules with a heat sink of the above-mentioned structure is demonstrated.

First, as shown in FIGS. 20 and 21, the first metal plate 222 made of copper and the ceramic substrate 221 are joined (copper plate joining step S201). Here, the ceramic substrate 221 made of Si ₃ N ₄ and the first metal plate 222 are joined by a so-called active metal method. In this active metal method, as shown in FIG. 21, a brazing material 225 made of Ag—Cu—Ti is disposed between a ceramic substrate 221 and a first metal plate 222, and the ceramic substrate 221 and the first metal plate 221. The metal plate 222 is joined.
In the present embodiment, the brazing material 225 made of Ag-27.4 mass% Cu-2.0 mass% Ti is used and heated at 850 ° C. for 10 minutes in a vacuum of 10 ⁻³ Pa. The ceramic substrate 221 and the first metal plate 222 are joined.

  Next, the second metal plate 223 is joined to the other surface side of the ceramic substrate 221 (aluminum plate joining step S202), and the second metal plate 223 and the heat sink 211 (top plate portion 212) are joined ( Heat sink joining step S203). In the present embodiment, the aluminum plate joining step S202 and the heat sink joining step S203 are performed simultaneously.

The additive element (Cu) is fixed to the bonding surface of the second metal plate 223 with the ceramic substrate 221 by sputtering to form the first fixing layer 251, and the top plate portion 212 of the heat sink 211 of the second metal plate 223. Then, an additional element (Cu) is fixed to the joint surface by sputtering to form the second fixed layer 252 (fixed layer forming step S211). Here, the amount of added elements in the first fixed layer 251 and the second fixed layer 252 is in the range of 0.01 mg / cm ² or more and 10 mg / cm ² or less, and in this embodiment, Cu is used as the additive element. The amount of Cu in the first fixing layer 251 and the second fixing layer 252 is set to 0.08 mg / cm ² or more and 2.7 mg / cm ² or less.

  Next, as shown in FIG. 21, the second metal plate 223 is laminated on the other surface side of the ceramic substrate 221. Furthermore, the top plate portion 212 of the heat sink 211 is laminated on the other surface side of the second metal plate 223 (lamination step S212).

Then, the first metal plate 222, the ceramic substrate 221, the second metal plate 223, and the top plate portion 212 are charged in the stacking direction (pressure 1 to 35 kgf / cm ² ) and charged into the vacuum heating furnace. And heating (heating step S213). Here, in this embodiment, the pressure in the vacuum heating furnace is set in a range of 10 ⁻³ to 10 ⁻⁶ Pa, and the heating temperature is set in a range of 550 ° C. or more and 650 ° C. or less.
Then, a first molten metal region is formed at the interface between the second metal plate 223 and the ceramic substrate 221, and a second molten metal region is formed at the interface between the second metal plate 223 and the top plate portion 212. become.

  Next, the first molten metal region and the second molten metal region are solidified by cooling (molten metal solidification step S214).

  In this way, the first metal plate 222, the ceramic substrate 221, the second metal plate 223, and the heat sink 211 (top plate portion 212) are joined, and the power module substrate 210 with a heat sink according to this embodiment is manufactured. Will be.

  According to the power module substrate with heat sink 210 according to the present embodiment configured as described above, the same operational effects as the power module substrate with heat sink according to the first and second embodiments described above can be obtained. Therefore, the heat from the heating element such as the semiconductor chip 3 mounted on the first metal plate 222 can be efficiently promoted, and the generation of cracks in the ceramic substrate 221 at the time of thermal cycle load can be suppressed. In addition, it is possible to provide a highly reliable power module substrate 210 with a heat sink.

  Further, since the first metal plate 222 and the ceramic substrate 221 are joined by the active metal method using the brazing material 225 of Ag—Cu—Ti, oxygen is supplied to the first metal plate 222 and the ceramic substrate 221. The power module substrate 220 can be configured without interposition.

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, although the second metal plate has been described as a rolled plate of pure aluminum having a purity of 99.99% or more, the present invention is not limited to this, and the second metal plate is made of aluminum having a proof stress of 30 N / mm ² or less. Anything can be used.

In the second embodiment, the Al ₂ O ₃ layer is formed by oxidizing AlN. However, the present invention is not limited to this, and Al ₂ is applied to the surface of the ceramic substrate by other means. An O ₃ layer may be formed.
Further, in the fixing layer forming step in the first embodiment and the second embodiment, it has been described that the additive element is fixed by sputtering. However, the present invention is not limited to this, and deposition, CVD, plating, or paste is not limited thereto. The additive element may be fixed by coating.

Moreover, although it demonstrated as what arrange | positions and joins one kind of additional element between a 2nd metal plate and a ceramic substrate, and a 2nd metal plate and a top-plate part, respectively, it is limited to this Instead, any one or two or more additive elements of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li may be provided.
Furthermore, when an easily oxidizable element such as Mg or Ca is used, it is preferable to arrange an additive element together with aluminum. Thereby, it is possible to suppress oxidation wear of easily oxidizable elements such as Mg and Ca.

In the present embodiment, the top plate of the heat sink has been described as being made of an A6063 alloy. However, the present invention is not limited to this, and other metal materials such as an A1100 alloy, an A3003 alloy, an A5052 alloy, and an A7N01 alloy. It may be configured by.
Furthermore, the structure of the heat sink is not limited to this embodiment, and a heat sink having another structure may be adopted.

  In the present embodiment, the power module substrate is described as being bonded to the heat sink. However, the present invention is not limited to this, and a plurality of power module substrates are bonded to the heat sink. May be.

  Furthermore, as shown in FIG. 22, the second metal plate 323 may have a structure in which a plurality of metal plates 323A and 323B are stacked. In this case, the metal plate 323A located on one side (the upper side in FIG. 22) of the second metal plate 323 is joined to the ceramic substrate 321 and the metal plate 323B located on the other side (the lower side in FIG. 22) is the heat sink. 311 is joined to the top plate portion 312. In FIG. 22, two metal plates 323A and 323B are stacked, but the number of stacked plates is not limited. Moreover, as shown in FIG. 22, the metal plates to be stacked may have different sizes and shapes, or may be adjusted to the same size and shape. Furthermore, the composition of these metal plates may be different.

A comparative experiment conducted to confirm the effectiveness of the present invention will be described.
A 0.635 mm thick ceramic substrate made of Al ₂ O _{3, a} 0.6 mm thick first metal plate made of a tough pitch copper rolled plate, and a 2.0 mm thick second metal plate made of aluminum And prepared. Here, in the second metal plate, by altering the purity of aluminum, yield strength were prepared three kinds of ^{10N / mm 2, 25N / mm} 2, 35N / mm 2.
An aluminum plate was prepared as a heat sink. Here, as an aluminum plate serving as a heat sink, a proof stress of 145 N / mm ² and a thickness of 5.0 mm (A6063 alloy), a proof stress of 110 N / mm ² and a thickness of 3.0 mm (A3003 alloy), and a proof stress of 95 N / mm ² And 4 types of thickness 5.0 mm (Al—Si alloy), proof stress 145 N / mm ² and thickness 1.0 mm (A6063 alloy) were prepared.

These ceramic substrates, the first metal plate, the second metal plate, and the heat sink are joined by the method described in the first embodiment, and as shown in Table 1, there are six types of power module substrates with heat sinks. Manufactured. Note that the amount of Cu in the fixing layer forming step S11 was set to 0.9 mg / cm ² . The pressurizing pressure in the heating step S13 was 5 kgf / cm ² , the heating temperature was 610 ° C., and the pressure in the vacuum heating furnace was 10 ⁻⁴ Pa.

  And the heat cycle (-45 degreeC-125 degreeC) was repeated 2000 times to these power module substrates with a heat sink, and the presence or absence of the crack of a ceramic substrate was confirmed. Also, the deformation of the heat sink was confirmed. The evaluation results are shown in Table 1.

In Comparative Example 1 in which the proof stress of the second metal plate was 35 N / mm ² , cracks were confirmed in the ceramic substrate. It is presumed that the thermal distortion caused by the difference in thermal expansion coefficient between the heat sink and the ceramic substrate could not be sufficiently relaxed by the second metal plate.
Further, Comparative Example 2 in which the aluminum plate constituting the heat sink has a proof stress of 95 N / mm ² and a thickness of 5.0 mm (Al—Si alloy), the proof stress is 145 N / mm ² and a thickness of 1.0 mm (A6063 alloy). In Comparative Example 3, the heat sink strength was insufficient and the heat sink was deformed.

In contrast, a second metal plate yield strength of from 30 N / mm ² or less of aluminum, Example yield strength with a heat sink thickness at 100 N / mm ² or more is equal to or greater than 2 mm, 1-3 No cracks were found in the ceramic substrate. Further, no deformation of the heat sink was observed.

1, 101, 201, 301 Power module 3 Semiconductor chip (electronic component)
10, 110, 210, 310 Power module substrate with heat sink 11, 111, 211, 311 Heat sink 12, 112, 212, 312 Top plate part 20, 120, 220, 320 Power module substrate 21, 121, 221, 321 Ceramics Substrate 22, 122, 222, 322 First metal plate 22A, 122A, 222A, 322A Mounting surface 23, 123, 223, 323 Second metal plate 30, 130, 230 Bonding interface (ceramic substrate / second metal plate )
32, 132, 232 Additive element high concentration portion 40, 140, 240 Bonding interface (second metal plate / top plate portion)
55 1st molten metal area (molten metal area)
56 Second molten metal region (molten metal region)
125 Al ₂ O ₃ layers

Claims (15)

A ceramic substrate, a first metal plate bonded to one surface of the ceramic substrate, a second metal plate bonded to the other surface of the ceramic substrate, and the other surface of the second metal plate A power module substrate with a heat sink comprising a heat sink bonded to the side,
The first metal plate is made of copper or a copper alloy, and one surface of the first metal plate is a mounting surface on which electronic components are mounted,
The second metal plate is made of aluminum having a proof stress of 30 N / mm ² or less,
The heat sink is made of a metal material having a proof stress of 100 N / mm ² or more, and has a thickness of 2 mm or more.   Of the second metal plate, at least one of a bonding interface with the ceramic substrate or a bonding interface with the heat sink is made of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, or Li. Any one or two or more additive elements are in solid solution, and the total concentration of the additive elements in the vicinity of the bonding interface in the second metal plate is in the range of 0.01% by mass to 5% by mass. The power module substrate with a heat sink according to claim 1, wherein the power module substrate has a heat sink.   Of the second metal plate, at one or two or more additive elements of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li are bonded to the ceramic substrate. 3. The heat sink with heat sink according to claim 1, wherein a high concentration portion of an additive element having a concentration of at least twice the concentration of the additive element in the second metal plate is formed. Power module substrate. The additive element high concentration portion is formed at the bonding interface with the ceramic substrate in the second metal plate,
The ceramic substrate is made of Al ₂ O ₃ , and the bonding interface including the high concentration portion of the additive element formed at the bonding interface with the ceramic substrate is analyzed by energy dispersive X-ray analysis Al, additive element, 4. The power module substrate with a heat sink according to claim 3, wherein the mass ratio of O is Al: additive element: O = 50 to 90 mass%: 1 to 30 mass%: 45 mass% or less. . The additive element high concentration portion is formed at the bonding interface with the ceramic substrate in the second metal plate,
The ceramic substrate is made of AlN, and Al, additive elements, O, and N are analyzed by energy dispersive X-ray analysis of the joint interface including the high concentration portion of the additive element formed at the joint interface with the ceramic substrate. The mass ratio of Al: additive element: O: N = 50 to 90% by mass: 1 to 30% by mass: 1 to 10% by mass: 25% by mass or less. Power module board with heat sink. The additive element high concentration portion is formed at the bonding interface with the ceramic substrate in the second metal plate,
The ceramic substrate is made of Si ₃ N ₄ , and the additive element is one or more of Cu, Ag, Zn, Mg, Ge, Ca, Ga, Li,
The mass ratio of Al, Si, additive elements, O, and N analyzed by energy dispersive X-ray analysis of the joint interface including the high concentration portion of the additive element formed at the joint interface with the ceramic substrate is Al: 4. Si: additive element: O: N = 15 to 45% by mass: 15 to 45% by mass: 1 to 30% by mass: 2 to 20% by mass: 25% by mass or less A power module substrate with a heat sink as described. The ceramic substrate is made of AlN, on at least one surface of said ceramic substrate from claim 1, characterized in that the Al ₂ O ₃ layer is formed of any one of claims 3 Power module substrate with heat sink.   A power module comprising the power module substrate with a heat sink according to any one of claims 1 to 7 and an electronic component mounted on the first metal plate. A ceramic substrate, a first metal plate bonded to one surface of the ceramic substrate, a second metal plate bonded to the other surface of the ceramic substrate, and the other surface of the second metal plate A method for manufacturing a power module substrate with a heat sink, comprising:
The first metal plate is made of copper or a copper alloy, the second metal plate is made of aluminum having a yield strength of 30 N / mm ² or less, and the heat sink is a metal having a yield strength of 100 N / mm ² or more. Composed of materials,
A copper plate joining step for joining the first metal plate and the ceramic substrate; an aluminum plate joining step for joining the second metal plate and the ceramic substrate; and the second metal plate and the heat sink. A heat sink joining process for joining,
In at least one of the aluminum plate bonding step and the heat sink bonding step, any one of Si, Cu, Ag, Zn, Mg, Ge, Ca, Ga, and Li is formed on the bonding interface of the second metal plate. A method for producing a power module substrate with a heat sink, wherein one or two or more additional elements are arranged and the second metal plate is joined.   In at least one of the aluminum plate bonding step and the heat sink bonding step, the additive element diffuses toward the second metal plate, thereby forming a molten metal region at the bonding interface. The method for manufacturing a power module substrate with a heat sink according to claim 9, wherein the metal regions are joined by solidifying. The amount of the additive element disposed at the bonding interface of the second metal plate is within a range of 0.01 mg / cm ² or more and 10 mg / cm ² or less. The manufacturing method of the board | substrate for power modules with a heat sink of description. 12. The alumina layer forming step of forming an Al ₂ O ₃ layer on at least one surface of the ceramic substrate is performed before the copper plate bonding step. Of manufacturing a power module substrate with a heat sink.   The method for manufacturing a power module substrate with a heat sink according to any one of claims 9 to 12, wherein the aluminum plate joining step and the heat sink joining step are performed simultaneously.   The method for manufacturing a power module substrate with a heat sink according to any one of claims 9 to 13, wherein aluminum is disposed together with the additive element at a bonding interface of the second metal plate.   15. The additive element is arranged at a bonding interface of the second metal plate by means selected from vapor deposition, CVD, sputtering, plating, or paste application. The manufacturing method of the board | substrate for power modules with a heat sink as described in any one of Claims.

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