TWI780113B - METHOD OF MANUFACTURING CERAMIC/Al-SiC COMPOSITE MATERIAL BONDED BODY AND METHOD OF MANUFACTURING POWER MODULE SUBSTRATE WITH HEAT SINK - Google Patents

Abstract

In a method of manufacturing a ceramic/Al-SiC composite material bonded body, an Al-SiC composite material has an aluminum material including Al-Si alloy in which the silicon amount is 0.1 atom% or more. The method includes: a step of forming a magnesium layer having 0.1 μm to 10 μm of a thickness at a surface of at least one of a ceramic member and the Al-SiC composite material; a step of laminating the ceramic member and the Al-SiC composite material via the magnesium layer to obtain a laminate; and a step of heating the laminate at 550^o C to 575^o C, thereby bonding the ceramic member and the Al-SiC composite material.

Description

Method for manufacturing ceramic/aluminum-silicon carbide composite material joint body, and method for manufacturing substrate for power module with heat sink

The present invention relates to a method for manufacturing a ceramic/aluminum-silicon carbide composite joint body formed by joining a ceramic component and an aluminum-silicon carbide (Al-SiC) composite material, and a ceramic substrate and a substrate for a power module. A method of manufacturing a base plate for a power module with a heat sink, in which heat sinks made of aluminum-silicon carbide composite materials are bonded.

Power semiconductor devices for high-power control used to control wind power generation, electric vehicles, hybrid vehicles, etc., generate a lot of heat, so the substrates on which they are mounted, for example, have been widely used in the past with AlN (aluminum nitride) , Al ₂ O ₃ (aluminum oxide), etc., and a circuit layer formed by bonding a metal plate with excellent conductivity to one surface of the ceramic substrate. A substrate for a power module. In addition, in order to efficiently dissipate heat generated by semiconductor elements mounted on the circuit layer, there are also substrates for power modules with heat sinks in which a heat sink is bonded to the other surface of the ceramic substrate.

As a material for the heat sink, there is known an aluminum-silicon carbide composite material (also called an aluminum-based composite material) having a porous body composed of silicon carbide and an aluminum material composed of aluminum or an aluminum alloy impregnated in the porous body. ).

For example, Patent Document 1 discloses a substrate for a heatsink-attached power module in which a heatsink made of an aluminum-silicon carbide composite material is bonded to a ceramic substrate on the top plate. In this patent document 1, as a method of bonding a ceramic substrate and an aluminum-silicon carbide composite material, the aluminum material of the aluminum-silicon carbide composite material is made of aluminum (pure aluminum) with a purity of 99.98% or more, and an aluminum-silicon-based solder is used for bonding. A method for ceramic substrates and aluminum-silicon carbide composites. In addition, as another method of joining the ceramic substrate and the aluminum-silicon carbide composite material, the aluminum material of the aluminum-silicon carbide composite material is an aluminum alloy (aluminum-silicon alloy) with a melting point below 600°C, and the aluminum-silicon carbide composite A method of forming a skin layer made of an aluminum-silicon alloy on the ceramic substrate side portion of the material, and melting a part of the skin layer. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2010-98058

[Problem to be Solved by the Invention]

However, as described in Patent Document 1, when using an aluminum-silicon-based solder to join a ceramic substrate and an aluminum-silicon carbide composite material in which the aluminum material is aluminum with a purity of 99.98% or more, the joining temperature must be lower than 600°C. high temperature. On the other hand, when a part of the skin layer of the aluminum-silicon carbide composite material is melted to join the aluminum-silicon carbide composite material having a skin layer composed of an aluminum-silicon alloy having a melting point of 600° C. The temperature drops below 600°C. However, it is difficult to melt only a part of the skin layer of the aluminum-silicon carbide composite material. If the skin layer is melted, the aluminum alloy in the aluminum-silicon carbide composite material is also melted, and part of it will be melted out, and there is a layer of aluminum alloy in the aluminum-silicon carbide composite material. There is a risk of voids (voids) in silicon composites. When voids are generated in the aluminum-silicon carbide composite material, it becomes an important cause of lowering the thermal conductivity of the aluminum-silicon carbide composite material.

The present invention is made in view of the aforementioned circumstances, and aims to provide a high-strength bonding ceramic member and aluminum-silicon carbide composite material without melting the aluminum material in the aluminum-silicon carbide composite material by heating at a relatively low temperature. A method for manufacturing a ceramic/aluminum-silicon carbide composite material junction of a silicon composite material, and a method for manufacturing a substrate for a power module with a heat sink attached. [Means for solving problems]

In order to solve such problems and achieve the aforementioned object, a method for manufacturing a ceramic/aluminum-silicon carbide composite joint body according to an aspect of the present invention is to join ceramic members, and have a porous body made of silicon carbide and impregnate the porous body in this porous body. An aluminum-silicon carbide composite material of an aluminum material composed of an aluminum-silicon alloy whose plastid has a silicon content of 0.1 atomic percent or more; characterized by having at least one of the aforementioned ceramic member and the aforementioned aluminum-silicon carbide composite material On the surface, a step of forming a magnesium layer with a thickness of 0.1 μm to 10 μm, and a step of laminating the aforementioned ceramic member and the aforementioned aluminum-silicon carbide composite material through the aforementioned magnesium layer to obtain a laminate, and by laminating the aforementioned The step of heating the body at a temperature range of 550°C to 575°C, and joining the aforementioned ceramic component and the aforementioned aluminum-silicon carbide composite material.

According to the manufacturing method of the ceramic/aluminum-silicon carbide composite joint body, the aluminum material of the aluminum-silicon carbide composite material is composed of an aluminum-silicon alloy with a silicon content of 0.1 atomic percent or more, and is arranged between the ceramic member and the silicon carbide composite material. The magnesium layer between the aluminum-silicon carbide composite materials is in contact with the aluminum-silicon alloy, so the ceramic component and the aluminum-silicon carbide composite material can be bonded by heating at a relatively low temperature of 550°C to 575°C. That is to say, while the magnesium in the magnesium layer removes the oxide film on the surface of the ceramic component or the aluminum-silicon carbide composite material, it diffuses into the aluminum material of the aluminum-silicon carbide composite material, and between the ceramic component and the aluminum-silicon carbide composite material, Mg ₂ Si formed by the reaction of aluminum, magnesium, silicon, and diffused magnesium and silicon forms a solid-liquid coexistence region where solid and liquid phases are mixed. Then, by solidification of the solid-liquid coexistence region, the ceramic member and the aluminum-silicon carbide composite material are bonded via the joint portion containing aluminum, magnesium, and silicon. Moreover, magnesium oxide is produced by reaction of these oxide films and magnesium. Then, the ceramic member and the aluminum-silicon carbide composite material can be joined with high strength by the part (joint part) solidified in this liquid phase.

In addition, the ceramic component and the aluminum-silicon carbide composite material are bonded to form a solid-liquid coexistence region, so the aluminum in the aluminum-silicon carbide composite material will not be melted out, and the ceramic substrate and the aluminum-silicon carbide composite material can be bonded . Furthermore, since the aluminum in the aluminum-silicon carbide composite material does not melt out, it is possible to suppress the occurrence of voids (voids) caused by the outflow of the aluminum material in the aluminum-silicon carbide composite material, or the cracking of the aluminum-silicon carbide composite material .

Here, if the silicon content of the aluminum material of the aluminum-silicon carbide composite material is less than 0.1 atomic percent, the amount of liquid phase in the solid-liquid coexistence area decreases, and the bondability between the ceramic substrate and the aluminum-silicon carbide composite material may decrease. In addition, when the thickness of the magnesium layer is less than 0.1 μm, the amount of Mg ₂ Si generated during heating decreases, thereby reducing the bondability between the ceramic substrate and the aluminum-silicon carbide composite material. On the other hand, when the thickness of the magnesium layer exceeds 10 μm, the liquid phase in the solid-liquid coexistence region increases and the bondability decreases. Furthermore, when the heating temperature is less than 550° C., the amount of the liquid phase in the solid-liquid coexistence region decreases, so that the joint strength decreases. When the temperature exceeds 575°C, melting of the heat sink base material occurs.

Here, in the method of manufacturing a ceramic/aluminum-silicon carbide composite material joint body according to an aspect of the present invention, in the aforementioned laminate, counting from the surface of the joint surface of the aforementioned aluminum-silicon carbide composite material and the aforementioned ceramic member The ratio (Si/Mg) of the amount of silicon present in the aforementioned aluminum-silicon alloy to the amount of magnesium present in the aforementioned magnesium layer up to a thickness of 50 μm is within the range of 0.01 to 99.0 in terms of atomic ratio. good.

In this case, Mg ₂ Si is easily generated in the solid-liquid coexistence region generated by heating, so that the ceramic member and the aluminum-silicon carbide composite material can be reliably bonded.

A method of manufacturing a substrate for a power module with a cooling block according to an aspect of the present invention is to join the aforementioned ceramic substrate to the substrate for a power module having a ceramic substrate and a circuit layer bonded to one side of the ceramic substrate, And a heat sink made of an aluminum-silicon carbide composite material composed of a porous body made of silicon carbide and an aluminum-silicon alloy impregnated in the porous body with a silicon content of more than 0.1 atomic percent; The invention comprises: a step of forming a magnesium layer with a thickness of 0.1 μm to 10 μm on the surface of at least one of the ceramic substrate and the aluminum-silicon carbide composite material; and laminating the ceramic substrate and the aluminum via the magnesium layer. -Silicon carbide composite material, a step of obtaining a laminate, and a step of joining the aforementioned ceramic substrate and the aforementioned aluminum-silicon carbide composite material by heating the obtained aforementioned laminate at a temperature range of 550°C to 575°C .

The manufacturing method of the substrate for the power module with heat sink according to this configuration is the same as the manufacturing method of the aforementioned ceramic/aluminum-silicon carbide composite material junction, by making the ceramic substrate and the aluminum-silicon carbide composite material Heating at a relatively low temperature above 550°C and below 575°C can prevent the aluminum in the aluminum-silicon carbide composite material from melting out and join with high strength.

Here, in the method of manufacturing a substrate for a power module with a heat sink according to an aspect of the present invention, in the laminate, the thickness is calculated from the surface of the bonding surface of the aluminum-silicon carbide composite material to the ceramic substrate. The ratio (Si/Mg) of the amount of silicon in the aluminum-silicon alloy present in the range up to 50 μm to the amount of magnesium present in the magnesium layer is preferably in the range of 0.01 to 99.0 in terms of atomic ratio.

In this case, as in the above-mentioned method of manufacturing the ceramic/aluminum-silicon carbide composite material joint, Mg ₂ Si is likely to be generated in the solid-liquid coexistence region, so the ceramic substrate and the aluminum-silicon carbide composite can be reliably joined. Material. [Effect of Invention]

According to the present invention, it is possible to provide a ceramic/aluminum-carbide composite material that can bond a ceramic member and an aluminum-silicon carbide composite material with high strength without melting the aluminum material in the aluminum-silicon carbide composite material by heating at a relatively low temperature. A method for manufacturing a silicon composite material junction, and a method for manufacturing a substrate for a power module with a heat sink attached.

Hereinafter, the method of manufacturing the ceramic/aluminum-silicon carbide composite material joint body of the present invention and the method of manufacturing the substrate for power modules with heat sinks will be described with reference to the drawings. In addition, each embodiment shown below is an example specifically described in order to make the gist of the present invention easier to understand, and should not be used to limit the scope of the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the characteristics of the present invention easy to understand, some important parts may be enlarged for convenience, and the dimensional ratio of each component is not limited to the same as the actual one.

First, the structure of the substrate for a power module with a heat sink obtained by the method for manufacturing a substrate for a power module with a heat sink according to an embodiment of the present invention will be described with reference to FIG. 1 and FIG. 2A and FIG. 2B .

In FIG. 1 , a substrate 1 for a power module with a cooling block includes a substrate 10 for a power module and a cooling block 20 . The power module substrate 10 includes a ceramic substrate 11 and a circuit layer 12 bonded to one surface (upper surface in FIG. 1 ) of the ceramic substrate 11 . The ceramic substrate 11 prevents the conductive connection between the circuit layer 12 and the heat sink 20, and is made of Si ₃ N ₄ (silicon nitride), AlN (aluminum nitride), Al ₂ O ₃ (oxide Aluminum) and other ceramics. In this embodiment, it is made of AlN. The thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5 mm, and is set at 0.635 mm in this embodiment.

The circuit layer 12 is formed by bonding an aluminum member made of aluminum or an aluminum alloy to one surface of the ceramic substrate 11 . As the aluminum member, aluminum with a purity of 99% by mass or higher (2N aluminum) or aluminum with a purity of 99.99% by mass or higher (4N aluminum) can be used. In this embodiment, a rolled sheet of 4N aluminum is used. The thickness of the circuit layer 12 is set within a range of not less than 0.1 mm and not more than 1.0 mm, and is set at 0.4 mm in this embodiment. The circuit layer 12 and the ceramic substrate 11 are bonded by, for example, Al—Si-based solder.

The heat dissipation block 20 is used for dissipating heat from the power module substrate 10 side. The cooling block 20 is provided with a channel 21 for the cooling fluid to circulate.

The heat slug 20 is made of an Al-SiC composite material (so-called AlSiC) 30 . The Al-SiC composite material 30 has a porous body 31 made of silicon carbide, and an aluminum material 32 made of aluminum or an aluminum alloy impregnated in the porous body 31 . The aluminum material 32 can use pure aluminum such as aluminum with a purity of 99 mass percent or more (2N aluminum) or aluminum with a purity of 99.99 mass percent or more (4N aluminum), or have Al: 80 mass percent or more and 99.99 mass percent or less, Si: 0.01 mass percent An aluminum alloy with a composition of not more than 13.5% by mass, Mg: not less than 0.03% by mass and not more than 5.0% by mass, and the remainder being impurities. In addition, aluminum alloys such as ADC12 or A356 can also be used. The Al-SiC composite material 30 may also have a skin layer 33. The skin layer 33 is a layer formed by exuding a part of the aluminum material 32 to the surface when the aluminum material 32 is melt-impregnated with SiC which becomes the porous body 31 to produce an Al-SiC composite material. That is, the skin layer 33 has the same composition as that of the aluminum material 32 . The thickness of the skin layer 33 is adjusted by cutting the exuded aluminum material. The thickness of the heat dissipation block 20 can be 0.5mm-5.0mm. Moreover, when the heat sink 20 is formed with a skin layer, the thickness is a thickness including the skin layer. In addition, the thickness of the skin layer corresponding to one side is preferably 0.01 to 0.1 times the thickness of the heat sink block 20 . Also, in the power module substrate 1 with a heat sink attached in this embodiment, the area of the heat sink 20 is set to be the same as the area of the ceramic substrate 11, or larger.

Here, the structure of the junction part of the ceramic substrate 11 and the heat sink 20 is demonstrated using FIG. 2A and FIG. 2B.

In FIG. 2A and FIG. 2B , the ceramic substrate 11 and the Al—SiC composite material 30 of the heat sink block 20 are bonded through the bonding portion 40 . FIG. 2A shows the case where the Al—SiC composite material 30 has a skin layer 33 , and the joint portion 40 is formed in the skin layer 33 . FIG. 2B shows the case where the Al—SiC composite material 30 does not have the skin layer 33 , and the joining portion 40 is formed in the aluminum material 32 of the Al—SiC composite material 30 .

The bonding portion 40 includes aluminum, magnesium, and silicon. The bonding part 40 is produced by heating the laminated body of the ceramic substrate 11 and the Al-SiC composite material 30 with a magnesium layer interposed therebetween in the manufacturing method of the substrate for a power module with a heat sink described later, and includes aluminum The layer formed by the solidification of the solid-liquid coexistence region of magnesium and silicon.

Magnesium oxide 41 is deposited on the joint portion 40 . Magnesium oxide 41 is deposited near the bonding interface between the ceramic substrate 11 and the bonding portion 40 . Magnesium oxide 41 is usually magnesia (MgO), spinel (MgAl ₂ O ₄ ), or a composite of these. Magnesium oxide 41, in the manufacturing method of the substrate for the power module with heat sink described later, is to exist in the surface of the ceramic substrate 11, the oxide film on the surface of the Al-SiC composite material 30, and the magnesium layer. The product produced by the reaction of magnesium. Mg ₂ Si may also be precipitated at the joint portion 40 .

Next, the manufacturing method of the substrate 1 for the power module with heat sink in this embodiment will be described with reference to FIG. 3 and FIG. 4 . As shown in FIG. 3 , the manufacturing method of the substrate 1 for a power module with a heat sink in this embodiment includes a step S01 of bonding a circuit layer and a step S02 of bonding a heat sink.

First, as shown in FIG. 4 , on one surface of the ceramic substrate 11 , the aluminum member 51 forming the circuit layer 12 is laminated with solder 52 interposed therebetween. Next, the circuit layer 12 is bonded to the ceramic substrate 11 by heating while applying pressure in the lamination direction. Through the above circuit layer bonding step S01, the power module substrate 10 of this embodiment is manufactured.

(Heat Slug Bonding Step S02 ) Next, the ceramic substrate 11 of the power module substrate 10 and the Al-SiC composite material 30 to be the heat sink 20 are joined to manufacture the heat sink attached power module substrate 1 . The heat slug bonding step S02, as shown in FIG. 3, includes a magnesium layer forming step S21, a laminating step S22, and a bonding step S23.

In the magnesium layer forming step S21 , as shown in FIG. 4 , a magnesium layer 53 is formed on at least one surface of the ceramic substrate 11 and the Al—SiC composite material 30 . In this embodiment, the magnesium layer 53 is formed on the surface of the Al—SiC composite material 30 .

The magnesium layer 53 preferably has a magnesium concentration of not less than 80 atomic percent, particularly preferably not less than 90 atomic percent. If the magnesium concentration of the magnesium layer 53 is 80 atomic percent or more, a solid-liquid coexistence region is likely to be formed in the bonding step S23 described later, and Mg ₂ Si is likely to be generated in the solid-liquid coexistence region.

The thickness of the magnesium layer 53 is in the range of 0.1 μm to 10 μm (the total thickness when formed on both the ceramic substrate 11 and the Al—SiC composite material 30 ). If the thickness of the magnesium layer 53 is too thin, the amount of Mg ₂ Si generated in the bonding step S23 described later will decrease, thereby reducing the bonding strength between the ceramic substrate 11 and the Al-SiC composite material 30 . On the other hand, if the thickness of the magnesium layer 53 is too thick, the liquid phase will be excessive in the solid-liquid coexistence region in the bonding step S23 described later, and the bondability between the ceramic substrate 11 and the Al-SiC composite material 30 may be reduced. .

As a method for forming the magnesium layer 53, a sputtering method, a vapor deposition method, or a method of applying a paste of magnesium powder and drying it can be used.

Next, in the lamination step S22, the magnesium layer 53 interposed between the ceramic substrate 11 and the Al-SiC composite material 30 is laminated to obtain a laminated body.

In the obtained laminated body, the amount of silicon in the aluminum-silicon alloy present in the range from the surface to the thickness of 50 μm at the joint surface of the Al-SiC composite material 30 and the ceramic substrate 11, and the amount of silicon present in the magnesium layer 53 The ratio of the amount of magnesium (Si/Mg) is in the range of 0.01 to 99.0 in terms of atomic ratio. If the amount of silicon and magnesium is within the aforementioned range, Mg ₂ Si necessary for bonding the ceramic substrate 11 and the Al-SiC composite material 30 is easily generated in the bonding step S23 described later, and the ceramic substrate 11 and the Al-SiC composite material 30 can be reliably bonded. - SiC composite material 30 . Si/Mg is preferably in the range of not less than 1.1 and not more than 6.7. Here, the amount of magnesium present in the magnesium layer 53 can be obtained from the purity, thickness, and density of the magnesium layer 53 . The amount of silicon in the range from the surface of the Al-SiC composite material 30 to a thickness of 50 μm can be obtained from the silicon content of the Al-SiC composite material 30 . Also, when the Al-SiC composite material 30 has a skin layer, the silicon content of the Al-SiC composite material 30 includes the silicon content in the skin layer 33 .

Next, in the bonding step S23, the obtained bonded body is heated in a temperature range of 550° C. to 575° C. while being pressurized in the lamination direction. By this heating, the magnesium in the magnesium layer 53 removes the oxide film existing on the surface of the ceramic substrate 11 or the Al-SiC composite material 30, and at the same time diffuses to the aluminum material 32 of the Al-SiC composite material 30. Between the composite materials 30 , a solid-liquid coexistence region is formed by the reaction of aluminum, magnesium, silicon, and Mg ₂ Si formed by the reaction of diffused magnesium and silicon. Next, by the solidification of the solid-liquid coexistence region, as shown in FIG. 2A and FIG. 2B , the ceramic substrate 11 and the Al-SiC composite material 30 are bonded via the bonding portion 40 containing aluminum, magnesium, and silicon. Also, when the Al—SiC composite material 30 has the skin layer 33 , the joint portion 40 is formed on the ceramic substrate 11 side in the skin layer 33 . When the skin layer 33 is not provided, the bonding portion 40 is formed on the ceramic substrate 11 side in the aluminum material 32 . In addition, magnesium oxide 41 is produced by the reaction of these oxide films and magnesium. In addition, when the joining temperature is high or the holding time is long, Mg ₂ Si may hardly be observed in the joining portion 40 . In addition, the solidification of the solid-liquid coexistence region can also be solidification by cooling, and the melting point of the liquid phase in the solid-liquid coexistence region can be raised by the diffusion of magnesium, etc., and solidification can be performed while maintaining the heating temperature, that is, the so-called isothermal solidification.

In this embodiment, as the bonding conditions of the above-mentioned bonded body, the load in the stacking direction is in the range of 0.1 MPa to 3.5 MPa (1 kgf/cm ² to 35 kgf/cm ² ), and the bonding temperature is 550 ° C or higher. In the range of 575°C or lower, the holding time is in the range of 15 minutes to 180 minutes. If the joining temperature is too low, there is a possibility that a solid-liquid coexistence region may not be generated. On the other hand, if the joining temperature is too high, the base material of the Al-SiC composite material 30 may melt. Also, the bonding temperature is preferably lower than the melting point of the aluminum material 32 in order to suppress the outflow of the aluminum material 32 of the Al-SiC composite material 30 . Also, if the applied load is too low, the solid-liquid coexistence region will not easily come into contact with the Al-SiC composite material 30, which may result in poor contact. If the applied load becomes too high, cracks or breakage may occur in the circuit layer 12, the ceramic substrate 11, or the Al—SiC composite material 30.

According to the manufacturing method of the power module substrate 1 with a heat sink of the present embodiment constituted as above, the magnesium in the magnesium layer 53 is diffused into the aluminum-silicon alloy in the Al-SiC composite material 30 in the heat sink bonding step S02 Forming a solid-liquid coexistence region and bonding the ceramic substrate 11 of the power module substrate 10 and the Al-SiC composite material 30 that becomes the heat sink block 20, so the aluminum material 32 in the Al-SiC composite material 30 will not be melted out, and The ceramic substrate 11 and the Al-SiC composite material 30 can be bonded with high strength. In addition, since the aluminum material in the Al-SiC composite material does not melt out, the occurrence of voids (voids) caused by the outflow of the aluminum material in the Al-SiC composite material or the cracking of the Al-SiC composite material can be suppressed.

Furthermore, in this embodiment, the amount of silicon in the aluminum-silicon alloy present in the range from the surface to the thickness of 50 μm on the joint surface of the Al-SiC composite material 30 and the ceramic substrate 11 is different from that present in the magnesium layer 53. The ratio of the amount of magnesium (Si/Mg) in the atomic ratio is in the range of 0.01 to 99.0, so Mg ₂ Si necessary for bonding the ceramic substrate 11 and the Al-SiC composite material 30 becomes easy to generate, and it can be reliably The ceramic substrate 11 and the Al-SiC composite material 30 are bonded together.

That is, with the substrate 1 for a power module with a heat sink obtained by the manufacturing method of this embodiment, the bonding strength between the ceramic substrate 11 and the heat sink 20 (Al-SiC composite material 30 ) is high. In addition, There are very few voids (voids) in the heat sink, so the thermal cycle reliability is excellent.

The embodiments of the present invention have been described above, but the present invention is not limited thereto, and can be appropriately changed within the range not departing from the technical idea of the present invention. For example, in this embodiment, the substrate for a power module with a heat sink is used as an example for description, but it is not limited to this, as long as it is a ceramic/Al-SiC composite material that joins a ceramic member and an Al-SiC composite material Just join.

In addition, in this embodiment, the rolled plate of 4N aluminum is bonded to form the circuit layer 12, but it is not limited to this, and a copper or copper alloy plate can also be formed by bonding a copper or copper alloy plate to the ceramic substrate 11 to form a copper or copper alloy structure. The circuit layer (thickness 0.3mm ~ 3.0mm). In this case, when joining a copper or copper alloy plate to the ceramic substrate 11, an active metal welding method using an Ag-Cu-Ti or Ag-Ti solder material can be suitably used. Furthermore, the circuit layer may also be composed of a laminate of aluminum and copper (or an alloy of these). In this case, an aluminum layer is formed on the ceramic substrate, and a copper layer is formed on the aluminum layer. [Example]

Confirmation experiments performed to confirm the effectiveness of the present invention will be described.

[Invention Examples 1 to 16, Comparative Examples 1 to 5] As shown in Table 1, prepare: a metal plate for circuit layer formation, a ceramic substrate (40mm×40mm, AlN and _{Al2O3 :} thickness 0.635mm, SiN 0.32mm), Al-SiC composite material (AlSiC) plate (50mm×60mm×thickness 5mm (in the case of skin layer: the skin layer is formed on both sides, and the thickness of one side is 0.2mm)), and solder. In addition, the melting point of the aluminum material of the Al-SiC composite material is 570°C for ADC12, 660°C for 4N aluminum, 655°C for 3N aluminum, and 650°C for 2N aluminum.

The metal plate for forming a circuit layer and the ceramic substrate were joined as follows to obtain a ceramic substrate on which a circuit layer was formed. When the metal plate for circuit layer formation is 4N-Al, solder (Al-7.5% by mass Si, thickness: 12μm) and layered. Next, the metal plate for forming a circuit layer is bonded to the ceramic substrate by heating while applying pressure in the lamination direction, thereby obtaining a ceramic substrate on which a circuit layer is formed. Also, the load in the lamination direction was 0.6 MPa, the bonding temperature was 645° C., and the holding time was 45 minutes. When the metal plate for circuit layer formation is copper, a copper plate (37mm×37mm×thickness 0.6mm) made of oxygen-free copper is laminated on one side of the ceramic substrate with solder (Ag-9.8 mass percent Ti) interposed, The bonding was carried out under conditions of a load of 0.6 MPa, a bonding temperature of 830° C., and a holding time of 30 minutes to obtain a ceramic substrate on which a circuit layer was formed.

Next, as shown in Table 1, a magnesium layer was formed to a thickness shown in Table 1 on one of the ceramic substrate and the Al—SiC composite material of the circuit layer to be joined. The magnesium layer is formed by a vapor deposition method (ion plating method).

The purity of the formed magnesium layer is related to the amount of silicon present in the aluminum material (aluminum-silicon alloy) present in the range from the surface of the joint surface of the Al-SiC composite material with the ceramic member to a thickness of 50 μm. The ratio of the amount of magnesium in the magnesium layer (Si/Mg) is shown in Table 1 below. In addition, Si/Mg is measured by the following method.

(Measurement method of Si/Mg) The amount of magnesium in the magnesium layer was obtained by measuring the purity and thickness of the magnesium layer and taking the density of the magnesium layer as 1.74 g/cm ³ . The purity of the magnesium layer was measured by EPMA, and the thickness was measured by cross-sectional SEM observation. The amount of silicon in the Al-Si alloy is obtained by measuring the silicon concentration of the skin layer in the case of an Al-SiC composite material having a skin layer. In the case of an Al-Si composite material without a skin layer, it can be obtained by measuring the silicon concentration in the Al-Si composite material. Silicon concentration was determined using EPMA. Next, the ratio of silicon to magnesium (Si/Mg) was obtained from the obtained amounts of magnesium and silicon.

Next, the ceramic substrate and the magnesium layer interposed by the Al-SiC composite material were laminated to obtain a laminate. Next, an Al-SiC composite material (heat slug) was bonded to a ceramic substrate by heating while applying pressure in the lamination direction, and an evaluation sample (substrate for a power module with a heat slug attached) was produced. The bonding conditions are as described in Table 1.

[From the previous examples 1 to 4] After bonding the circuit layer in the same manner as in the present invention example 1, on the other side of the ceramic substrate on which the circuit layer is formed, the Al-Si-based solder foil described in Table 1 is interposed between the Al-SiC composite material. Then, by lamination and heating while applying pressure in the lamination direction, an evaluation sample (substrate for power module with heat sink) was produced.

(Initial Bondability) Using the obtained evaluation samples, the bonding ratio between the ceramic substrate and the heat sink was measured, and the initial bondability was evaluated. Specifically, it is evaluated using an ultrasonic flaw detection device (INSIGHT-300 manufactured by Insight Corporation), and is calculated by the following formula. Here, the so-called initial bonding area is the area to be bonded before bonding, that is, the area of the ceramic substrate (40 mm×40 mm). After binarizing the ultrasonic flaw detection image, the peeling is displayed as a white part in the joint, so the area of the white part is the peeling area. The evaluation results are shown in Table 1. (joint rate)={(initial joint area)-(non-joint area)}/(initial joint area)×100

(Jointability after thermal cycle) The thermal shock tester TSB-51 manufactured by Espec Co., Ltd. was used to test the bonding property after thermal cycle. 2000 cycles of 10 minutes at -40°C and 10 minutes at 175°C were implemented, and the conjugation rate was measured and evaluated in the same manner as above. The evaluation results are shown in Table 1.

(Evaluation of Base Metal Melting) Visually observe the surface of the Al-SiC composite material of the evaluation sample, and evaluate the sample where the outflow or crack of aluminum caused by the melting of the base material was confirmed as "B", and the sample that was not confirmed The evaluation of the sample was "A". 5A and 5B are side photographs of an example of an Al-SiC composite material in which the base material is melted. Fig. 5A is a side photograph of an Al-SiC composite material in which aluminum outflow by melting of the base material has occurred. Fig. 5B is a side photograph of a corner portion of an Al-SiC composite material where cracks due to base metal melting have occurred. As shown in FIG. 5A , when the outflow of aluminum due to the melting of the base material occurs, aluminum exists in spherical form on the surface of the Al-SiC composite material.

In the former example 1 and the former example 2 joined at 610° C. using Al-Si solder foil or Al-Si-Mg solder foil, fusion of the base material was confirmed in the Al-SiC composite material. In the conventional example 3 and the conventional example 4 which joined at 560 degreeC, the joining rate was very low. Comparative example 1 in which the magnesium layer is thinner than 0.1 μm, comparative example 2 in which the magnesium layer is thicker than 10 μm, comparative example 3 in which the silicon concentration of the aluminum material of the Al-SiC composite material is less than 0.1 atomic percent, and joint In Comparative Example 4 where the temperature was low, the bonding ratios were all low. In Comparative Example 5, where the joining temperature was high, melting of the base material occurred.

On the other hand, in the substrates for power modules with heat slugs obtained in the examples of the present invention, it was confirmed that the base material did not melt, and the bonding ratio between the ceramic substrate and the Al-SiC composite material (heat slug) also showed a high value. [industrial availability]

According to the present invention, it is possible to provide a ceramic/aluminum-carbide composite material that can bond a ceramic member and an aluminum-silicon carbide composite material with high strength without melting the aluminum material in the aluminum-silicon carbide composite material by heating at a relatively low temperature. A method for manufacturing a silicon composite material junction, and a method for manufacturing a substrate for a power module with a heat sink attached.

1‧‧‧Substrate for power module with heat sink 10‧‧‧Substrate for power module 11‧‧‧Ceramic substrate 12‧‧‧Circuit layer 20‧‧‧Heat block 21‧‧‧Runner 30‧‧‧Aluminum -Silicon carbide composite material 31‧‧‧porous body 32‧‧‧aluminum material 33‧‧‧skin layer 40‧‧‧joint part 41‧‧‧magnesium oxide 51‧‧‧aluminum component 52‧‧‧solder 53‧‧ ‧Magnesium layer

1 is a cross-sectional view of a substrate for a power module with a heat sink obtained by a method for manufacturing a substrate for a power module with a heat sink according to an embodiment of the present invention. Fig. 2A is an enlarged cross-sectional view of the part where the ceramic substrate and the metal layer of the substrate for a power module with a heat sink obtained by the manufacturing method of the substrate for a power module with a heat sink according to the embodiment of the present invention are bonded. Fig. 2B is an enlarged cross-sectional view of the bonded part of the ceramic substrate and the metal layer of the substrate for a power module with a heat sink obtained by the method of manufacturing the substrate for a power module with a heat sink according to the embodiment of the present invention. Fig. 3 is a flow chart showing a method of manufacturing a substrate for a power module with a heat sink according to an embodiment of the present invention. Fig. 4 is an explanatory diagram showing a method of manufacturing a substrate for a power module with a heat sink according to an embodiment of the present invention. Fig. 5A is a photo illustrating the aluminum-silicon carbide composite material in which the base metal has been melted in the example. Fig. 5B is a photo illustrating the aluminum-silicon carbide composite material in which the base metal is melted in the embodiment.

1‧‧‧Substrate for power module with heat sink

10‧‧‧Substrates for power modules

11‧‧‧Ceramic substrate

12‧‧‧circuit layer

20‧‧‧Heat block

21‧‧‧Runner

30‧‧‧Aluminum-silicon carbide composite material

31‧‧‧porous body

32‧‧‧Aluminum

Claims (4)

A method for manufacturing a ceramic/aluminum-silicon carbide composite material joint body, which is to joint ceramic components, and a porous body composed of silicon carbide and an aluminum-silicon alloy with a silicon content of 0.1 atomic percent or more impregnated in the porous body An aluminum-silicon carbide composite material composed of an aluminum material; characterized by comprising: a step of forming a magnesium layer with a thickness of 0.1 μm to 10 μm on at least one surface of the aforementioned ceramic member and the aforementioned aluminum-silicon carbide composite material , and a step of laminating the aforementioned ceramic member and the aforementioned aluminum-silicon carbide composite material through the aforementioned magnesium layer to obtain a laminate, and heating the aforementioned laminate at a temperature range of 550°C to 575°C, intervening The step of joining the aforementioned ceramic component and the aforementioned aluminum-silicon carbide composite material at the joint portion where magnesium is diffused in the aforementioned aluminum-silicon carbide composite material; the aforementioned aluminum-silicon carbide composite material has a larger area than the aforementioned ceramic component. A method for manufacturing a ceramic/aluminum-silicon carbide composite joint body as claimed in claim 1 of the scope of the patent application, wherein in the aforementioned laminate, the thickness is calculated from the surface of the joint surface of the aforementioned aluminum-silicon carbide composite material and the aforementioned ceramic member to the thickness The ratio (Si/Mg) of the amount of silicon in the aluminum-silicon alloy present in the range up to 50 μm to the amount of magnesium present in the magnesium layer is within the range of 0.01 to 99.0 in terms of atomic ratio. A method of manufacturing a substrate for a power module with a cooling block, which is to join the aforementioned ceramic substrate with a substrate for a power module having a ceramic substrate and a circuit layer bonded to one side of the ceramic substrate, and a substrate made of silicon carbide The porous body and the aluminum-silicon carbide composite material composed of an aluminum-silicon alloy impregnated in the porous body with a silicon content of 0.1 atomic percent or more; it is characterized by: A step of forming a magnesium layer with a thickness of 0.1 μm to 10 μm on at least one surface of the substrate and the aluminum-silicon carbide composite material, and laminating the ceramic substrate and the aluminum-silicon carbide composite material through the magnesium layer , the step of obtaining the laminated body, and by heating the obtained laminated body at a temperature range of 550°C to 575°C, joining the aforementioned ceramics through the joint portion where magnesium is diffused in the aforementioned aluminum-silicon carbide composite material The step of the substrate and the aforementioned aluminum-silicon carbide composite material; the aforementioned aluminum-silicon carbide composite material has a larger area than the aforementioned ceramic substrate. A method of manufacturing a substrate for a power module with a heat sink attached in claim 3 of the scope of the patent application, wherein in the aforementioned laminate, the thickness is 50 μm from the surface of the bonding surface of the aforementioned aluminum-silicon carbide composite material to the aforementioned ceramic substrate The amount of silicon in the aforementioned aluminum-silicon alloy existing in the range up to now, and the amount of magnesium existing in the aforementioned magnesium layer The amount ratio (Si/Mg) is in the range of 0.01 to 99.0 in terms of atomic ratio.

Images