WO2023286860A1 - Copper/ceramic bonded body and insulated circuit board - Google Patents

Copper/ceramic bonded body and insulated circuit board Download PDF

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Publication number
WO2023286860A1
WO2023286860A1 PCT/JP2022/027876 JP2022027876W WO2023286860A1 WO 2023286860 A1 WO2023286860 A1 WO 2023286860A1 JP 2022027876 W JP2022027876 W JP 2022027876W WO 2023286860 A1 WO2023286860 A1 WO 2023286860A1
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Prior art keywords
copper
active metal
layer
thickness
region
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PCT/JP2022/027876
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French (fr)
Japanese (ja)
Inventor
伸幸 寺▲崎▼
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三菱マテリアル株式会社
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Publication of WO2023286860A1 publication Critical patent/WO2023286860A1/en

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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B37/00—Joining burned ceramic articles with other burned ceramic articles or other articles by heating
    • C04B37/02—Joining burned ceramic articles with other burned ceramic articles or other articles by heating with metallic articles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H01L23/13—Mountings, e.g. non-detachable insulating substrates characterised by the shape
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern

Definitions

  • the present invention provides a copper/ceramic bonded body in which a copper member made of copper or a copper alloy and a ceramic member are joined together, and an insulating circuit in which a copper plate made of copper or a copper alloy is joined to the surface of a ceramic substrate. It relates to substrates.
  • a power module, an LED module, and a thermoelectric module have a structure in which a power semiconductor element, an LED element, and a thermoelectric element are joined to an insulating circuit board in which a circuit layer made of a conductive material is formed on one side of an insulating layer.
  • power semiconductor elements for high power control used to control wind power generation, electric vehicles, hybrid vehicles, etc. generate a large amount of heat during operation.
  • Patent Document 1 proposes an insulated circuit board in which a circuit layer and a metal layer are formed by bonding copper plates to one side and the other side of a ceramic substrate.
  • copper plates are arranged on one surface and the other surface of a ceramic substrate with an Ag—Cu—Ti brazing material interposed therebetween, and the copper plates are joined by heat treatment (so-called active metal brazing method).
  • Patent Document 2 proposes a power module substrate in which a copper plate made of copper or a copper alloy and a ceramic substrate made of AlN or Al 2 O 3 are bonded using a bonding material containing Ag and Ti. ing. Furthermore, Patent Document 3 proposes a power module substrate in which a copper plate made of copper or a copper alloy and a ceramic substrate made of silicon nitride are bonded using a bonding material containing Ag and Ti. As described above, when a copper plate and a ceramic substrate are bonded using a bonding material containing Ti, Ti, which is an active metal, reacts with the ceramic substrate, thereby improving the wettability of the bonding material and the copper plate. The bonding strength with the ceramic substrate is improved.
  • the heat generation temperature of the semiconductor elements mounted on the insulated circuit board tends to be higher, and the insulated circuit board is required to have higher cooling/heating cycle reliability to withstand severe cooling/heating cycles.
  • Ti which is an active metal
  • an intermetallic compound containing Cu and Ti precipitates.
  • the vicinity of the joint interface becomes hard, cracks may occur in the ceramic member during thermal cycle loading, and there is a risk of deterioration in thermal cycle reliability.
  • the present invention has been made in view of the above-mentioned circumstances. It is an object of the present invention to provide an insulated circuit board made of this copper/ceramic bonded body.
  • the inventors of the present invention conducted intensive studies, and found that when a ceramic member and a copper member are joined using a joining material containing an active metal, the liquid phase generated during joining is The active metal is repelled from the central portion to the peripheral edge portion side, and a relatively large amount of active metal exists in the peripheral edge portion of the copper member. It was found that there is a tendency to be harder than the region. Then, the inventors have found that stress concentrates on the peripheral edge region of the hard copper member at the bonding interface during a thermal cycle load, and cracking of the ceramic member is likely to occur.
  • a copper/ceramic joined body is a copper member obtained by joining a copper member made of copper or a copper alloy and a ceramic member.
  • a ceramic bonded body wherein an active metal compound layer is formed on the ceramic member side at the bonding interface between the ceramic member and the copper member, and the active metal compound layer is formed on the ceramic member side of the copper member.
  • the copper/ceramic joined body has the copper member and the ceramic member, and the copper member and the ceramic member are joined together.
  • the maximum reaching distance LA from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper member and the central portion of the copper member Since the maximum reachable distance LB from the active metal compound layer of the active metal diffusion region in the region is in the range of 20 ⁇ m or more and 80 ⁇ m or less, the ceramic member and the copper member are firmly bonded by the active metal. In addition, hardening of the bonding interface is suppressed.
  • the difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper member and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper member is 10 ⁇ m or less. Therefore, it is possible to suppress the peripheral region of the copper member from becoming relatively hard at the joint interface, suppress the occurrence of cracks in the ceramic member under thermal cycle load, and have excellent thermal cycle reliability. .
  • the thickness t1A of the active metal compound layer formed in the peripheral region of the copper member and the thickness t1A formed in the central region of the copper member is in the range of 0.05 ⁇ m or more and 1.2 ⁇ m or less, and the thickness ratio t1A / t1B is in the range of 0.7 or more and 1.4 or less. is preferred.
  • the thickness t1A of the active metal compound layer formed in the peripheral region of the copper member and the thickness t1B of the active metal compound layer formed in the central region of the copper member are 0.05 ⁇ m.
  • the thickness is within the range of 1.2 ⁇ m or less, the ceramic member and the copper member are reliably and strongly bonded by the active metal, and hardening of the bonding interface is further suppressed. Further, since the thickness ratio t1A / t1B is within the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper member. Therefore, it is possible to further suppress the occurrence of cracks in the ceramic member under thermal cycle load.
  • an Ag—Cu alloy layer is formed on the copper member side at the bonding interface between the ceramic member and the copper member, and the copper member
  • the thickness t2 A of the Ag--Cu alloy layer formed in the peripheral region of the and the thickness t2 B of the Ag--Cu alloy layer formed in the central region of the copper member are in the range of 1 ⁇ m or more and 30 ⁇ m or less. and the thickness ratio t2A / t2B is preferably in the range of 0.7 or more and 1.4 or less.
  • the thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper member and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper member are 1 ⁇ m. Since the thickness is within the range of 30 ⁇ m or less, the Ag of the bonding material sufficiently reacts with the copper member, so that the ceramic member and the copper member are reliably and firmly bonded, and the bonding interface is further hardened. Suppressed. Since the thickness ratio t2A / t2B is in the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper member. is not generated, and the occurrence of cracks in the ceramic member under thermal cycle load can be further suppressed.
  • An insulated circuit board is an insulated circuit board in which a copper plate made of copper or a copper alloy is bonded to a surface of a ceramic substrate, wherein the bonding interface between the ceramic substrate and the copper plate includes: An active metal compound layer is formed on the ceramic substrate side, and active metals (Ti, Zr, Nb, Hf) diffuse from the ceramic substrate side to the copper plate side on the ceramic substrate side of the copper plate.
  • an active metal diffusion region in which the concentration of the active metal in the copper plate is 0.5% by mass or more is formed, and from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the maximum reachable distance LB of the active metal diffusion region from the active metal compound layer in the central region of the copper plate are within the range of 20 ⁇ m or more and 80 ⁇ m or less, and the copper plate
  • the difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper plate is 10 ⁇ m or less.
  • the insulating circuit board has the ceramic substrate and the copper plate, and the copper plate is joined to the surface of the ceramic substrate.
  • the maximum reaching distance LA from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active distance in the central region of the copper plate Since the maximum reachable distance L B of the metal diffusion region from the active metal compound layer is in the range of 20 ⁇ m or more and 80 ⁇ m or less, the ceramic substrate and the copper plate are firmly bonded by the active metal, and the bonding interface is hardening is suppressed.
  • the difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper plate is 10 ⁇ m or less. Therefore, it is possible to suppress the peripheral region of the copper plate from becoming relatively hard at the joint interface, suppress the occurrence of cracks in the ceramic substrate under thermal cycle loads, and have excellent thermal cycle reliability.
  • the thickness t1A of the active metal compound layer formed in the peripheral region of the copper plate and the active metal layer formed in the central region of the copper plate is in the range of 0.05 ⁇ m or more and 1.2 ⁇ m or less, and the thickness ratio t1A / t1B is in the range of 0.7 or more and 1.4 or less.
  • the thickness t1A of the active metal compound layer formed in the peripheral region of the copper plate and the thickness t1B of the active metal compound layer formed in the central region of the copper plate are 0.05 ⁇ m or more.
  • the thickness is within the range of 0.2 ⁇ m or less, the ceramic substrate and the copper plate are reliably and strongly bonded by the active metal, and hardening of the bonding interface is further suppressed. Further, since the thickness ratio t1A / t1B is within the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper plate. Moreover, it is possible to further suppress the occurrence of cracks in the ceramic substrate under thermal cycle load.
  • an Ag—Cu alloy layer is formed on the side of the copper plate at the bonding interface between the ceramic substrate and the copper plate, and in the peripheral region of the copper plate.
  • the thickness t2 A of the Ag—Cu alloy layer formed and the thickness t2 B of the Ag—Cu alloy layer formed in the central region of the copper plate are in the range of 1 ⁇ m or more and 30 ⁇ m or less, and the thickness ratio It is preferable that t2A / t2B is in the range of 0.7 or more and 1.4 or less.
  • the thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper plate and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper plate are 1 ⁇ m or more and 30 ⁇ m. Since it is within the following range, the Ag of the bonding material sufficiently reacts with the copper plate, and the ceramic substrate and the copper plate are reliably and strongly bonded, and hardening of the bonding interface is further suppressed. Since the thickness ratio t2A / t2B is in the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper plate. In addition, it is possible to further suppress the occurrence of cracks in the ceramic substrate under a thermal cycle load.
  • a copper/ceramic joint that can suppress the occurrence of cracks in a ceramic member even when a severe thermal cycle is applied and has excellent thermal cycle reliability, and the copper/ceramic It is possible to provide an insulated circuit board made of a bonded body.
  • FIG. 1 is a schematic explanatory diagram of a power module using an insulated circuit board according to an embodiment of the present invention
  • FIG. FIG. 2 is an enlarged explanatory view of a bonding interface between a circuit layer and a metal layer of an insulated circuit board and a ceramic substrate according to an embodiment of the present invention
  • (a) is an explanatory diagram of the peripheral region and the central region of the circuit layer and the metal layer
  • (b) is the peripheral region
  • (c) is the central region.
  • 1 is a flowchart of a method for manufacturing an insulated circuit board according to an embodiment of the present invention
  • FIG. It is a schematic explanatory drawing of the manufacturing method of the insulation circuit board which concerns on embodiment of this invention.
  • FIG. 4 is an explanatory diagram of a bonding material disposing step in the method of manufacturing an insulated circuit board according to the embodiment of the present invention;
  • the copper/ceramic bonded body according to the present embodiment includes a ceramic substrate 11 as a ceramic member made of ceramics, and a copper plate 42 (circuit layer 12) and a copper plate 43 (metal layer 13) as copper members made of copper or a copper alloy. is an insulating circuit board 10 formed by bonding the .
  • FIG. 1 shows a power module 1 having an insulated circuit board 10 according to this embodiment.
  • This power module 1 includes an insulating circuit board 10 on which a circuit layer 12 and a metal layer 13 are arranged, and a semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the circuit layer 12 via a bonding layer 2. and a heat sink 5 arranged on the other side (lower side in FIG. 1) of the metal layer 13 .
  • the semiconductor element 3 is made of a semiconductor material such as Si.
  • the semiconductor element 3 and the circuit layer 12 are bonded via the bonding layer 2 .
  • the bonding layer 2 is made of, for example, a Sn--Ag-based, Sn--In-based, or Sn--Ag--Cu-based solder material.
  • the heat sink 5 is for dissipating heat from the insulating circuit board 10 described above.
  • the heat sink 5 is made of copper or a copper alloy, and is made of phosphorus-deoxidized copper in this embodiment.
  • the heat sink 5 is provided with a channel through which cooling fluid flows.
  • the heat sink 5 and the metal layer 13 are joined by a solder layer 7 made of a solder material.
  • the solder layer 7 is made of, for example, a Sn--Ag-based, Sn--In-based, or Sn--Ag--Cu-based solder material.
  • the insulating circuit board 10 of the present embodiment includes a ceramic substrate 11, a circuit layer 12 provided on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and a ceramic substrate. and a metal layer 13 disposed on the other surface (lower surface in FIG. 1) of the substrate 11 .
  • the ceramics substrate 11 is made of ceramics such as silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), alumina (Al 2 O 3 ), etc., which are excellent in insulation and heat dissipation.
  • the ceramic substrate 11 is made of aluminum nitride (AlN), which has excellent heat dissipation properties.
  • the thickness of the ceramic substrate 11 is set within a range of, for example, 0.2 mm or more and 1.5 mm or less, and is set to 0.635 mm in this embodiment.
  • the circuit layer 12 is formed by bonding a copper plate 42 made of copper or a copper alloy to one surface (upper surface in FIG. 4) of the ceramic substrate 11. As shown in FIG. In this embodiment, the circuit layer 12 is formed by bonding a rolled plate of oxygen-free copper to the ceramic substrate 11 .
  • the thickness of the copper plate 42 that forms the circuit layer 12 is set within a range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in this embodiment.
  • the metal layer 13 is formed by bonding a copper plate 43 made of copper or a copper alloy to the other surface of the ceramic substrate 11 (the lower surface in FIG. 4).
  • the metal layer 13 is formed by bonding a rolled plate of oxygen-free copper to the ceramic substrate 11 .
  • the thickness of the copper plate 43 that forms the metal layer 13 is set within a range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in this embodiment.
  • an active metal compound layer 21 and an Ag—Cu alloy layer 22 are formed in order from the ceramic substrate 11 side at the bonding interface between the ceramic substrate 11, the circuit layer 12 and the metal layer 13. ing. It can also be said that the active metal compound layer 21 is part of the ceramic substrate 11 . It can also be said that the Ag—Cu alloy layer 22 is part of the circuit layer 12 and the metal layer 13 . Therefore, the bonding interface between the ceramic substrate 11 and the circuit layer 12 and metal layer 13 (copper plates 42 and 43) is the interface between the active metal compound layer 21 and the Ag--Cu alloy layer 22.
  • the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13 is the active metal compound layer 21, the circuit layer 12 and the metal layer 13 (copper plate 42 , 43).
  • the active metal In the circuit layer 12 and the metal layer 13, the active metal (Ti in this embodiment) diffuses toward the circuit layer 12 and the metal layer 13 on the side of the bonding interface with the ceramic substrate 11, thereby forming a circuit.
  • An active metal diffusion region 23 is formed in which the active metal concentration in the layer 12 and the metal layer 13 is 0.5 mass % or more.
  • the interface structure between the peripheral region A and the central region B of the circuit layer 12 and the metal layer 13 is defined as follows.
  • the peripheral region A of the circuit layer 12 and the metal layer 13 is a cross section along the lamination direction of the circuit layer 12 and the metal layer 13 and the ceramic substrate 11. 2, the region extends from the widthwise end of the circuit layer 12 and the metal layer 13 to 200 ⁇ m further inward in the width direction from a position 20 ⁇ m inward from the widthwise end.
  • the central region B of the circuit layer 12 and the metal layer 13 is the circuit layer 12 in the cross section along the lamination direction of the circuit layer 12 and the metal layer 13 and the ceramic substrate 11. and a region of 200 ⁇ m in the width direction including the center of the metal layer 13 in the width direction.
  • the maximum The reaching distance LA is in the range of 20 ⁇ m or more and 80 ⁇ m or less.
  • the maximum reach from the active metal compound layer 21B of the active metal diffusion region 23B is The distance LB is within the range of 20 ⁇ m or more and 80 ⁇ m or less.
  • the maximum reaching distance LA of the active metal diffusion region 23A in the peripheral region A of the bonding interface between the ceramic substrate 11, the circuit layer 12, and the metal layer 13, the ceramic substrate 11, the circuit layer 12, and the The difference from the maximum reaching distance LB of the active metal diffusion region 23B in the central region B of the bonding interface with the metal layer 13 is 10 ⁇ m or less.
  • the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13, and the thickness t1 A of the ceramic substrate 11 and the circuit layer 13 is in the range of 0.05 ⁇ m or more and 1.2 ⁇ m or less, and the thickness ratio It is preferable that t1A / t1B is in the range of 0.7 or more and 1.4 or less.
  • the active metal compound layer 21 is a layer made of a compound of an active metal (at least one selected from Ti, Zr, Nb, and Hf) used in the bonding material 45.
  • FIG. More specifically, when the ceramic substrate is made of silicon nitride (Si 3 N 4 ) or aluminum nitride (AlN), the layer becomes a nitride of these active metals, and the ceramic substrate is made of alumina (Al 2 O 3 ), the layer consists of oxides of these active metals.
  • the active metal compound layers 21 (21A, 21B) are formed by aggregating active metal compound particles. The average particle size of these particles is 10 nm or more and 100 nm or less.
  • the active metal compound layers 21 (21A, 21B) are made of titanium nitride (TiN). Configured. That is, the active metal compound layers 21 (21A, 21B) are formed by aggregation of particles of titanium nitride (TiN) having an average particle diameter of 10 nm or more and 100 nm or less.
  • the ratio t2A / t2B to the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the bonding interface between the layer 12 and the metal layer 13 is in the range of 0.7 or more and 1.4 or less. preferably within.
  • the thickness of the Ag--Cu alloy layers 22 (22A, 22B) is preferably 1 ⁇ m or more and 30 ⁇ m or less.
  • FIG. 1 A method for manufacturing the insulated circuit board 10 according to the present embodiment will be described below with reference to FIGS. 3 and 4.
  • FIG. 1 A method for manufacturing the insulated circuit board 10 according to the present embodiment will be described below with reference to FIGS. 3 and 4.
  • a copper plate 42 to be the circuit layer 12 and a copper plate 43 to be the metal layer 13 are prepared. Then, a bonding material 45 is applied to the bonding surfaces of the copper plate 42 to be the circuit layer 12 and the copper plate 43 to be the metal layer 13 and dried.
  • the coating thickness of the paste-like bonding material 45 is preferably within the range of 10 ⁇ m or more and 50 ⁇ m or less after drying. In this embodiment, the paste bonding material 45 is applied by screen printing.
  • the bonding material 45 contains Ag and active metals (Ti, Zr, Nb, Hf).
  • an Ag--Ti based brazing material (Ag--Cu--Ti based brazing material) is used as the bonding material 45.
  • the Ag--Ti-based brazing material (Ag--Cu--Ti-based brazing material) contains, for example, 0% by mass or more and 45% by mass or less of Cu, and 0.5% by mass or more and 20% by mass of Ti, which is an active metal. It is preferable to use a composition having a content in the range of mass % or less, with the balance being Ag and unavoidable impurities.
  • the specific surface area of Ag powder contained in the bonding material 45 is preferably 0.15 m 2 /g or more, more preferably 0.25 m 2 /g or more, and more preferably 0.40 m 2 /g or more. is more preferred.
  • the specific surface area of the Ag powder contained in the bonding material 45 is preferably 1.40 m 2 /g or less, more preferably 1.00 m 2 /g or less, and 0.75 m 2 /g or less. is more preferable.
  • the particle size of the Ag powder contained in the paste-like bonding material 45 preferably has a D10 of 0.7 ⁇ m or more and 3.5 ⁇ m or less and a D100 of 4.5 ⁇ m or more and 23 ⁇ m or less. D10 is the particle size at which the cumulative frequency is 10% on a volume basis in the particle size distribution measured by a laser diffraction scattering particle size distribution measurement method, and D100 is the particle size at which the cumulative frequency is 100% on a volume basis. .
  • the bonding material 45 is applied so as to be thinner than the coating thickness of the bonding material 45B in the central portion of the copper plate 43 that becomes the metal layer 13 .
  • the difference between the coating thickness of the bonding material 45A in the peripheral edge portion of the copper plate 42 serving as the circuit layer 12 and the copper plate 43 serving as the metal layer 13 and the coating thickness of the bonding material 45B in the central portion is in the range of 5 ⁇ m or more and 15 ⁇ m or less. It is preferable to The peripheral portion to which the bonding material 45A is applied is a portion of the peripheral portion that includes the peripheral portion area and has an area of 1.5% to 10% of the surface area of the copper plates 42 and 43, and the maximum line width of the peripheral portion is 1 mm. is.
  • the central portion to which the bonding material 45B is applied is a central portion that includes the central region and has an area of 90% to 98.5% of the surface areas of the copper plates 42 and 43 .
  • a copper plate 42 to be the circuit layer 12 is laminated on one surface (upper surface in FIG. 4) of the ceramic substrate 11 with a bonding material 45 interposed therebetween, and on the other surface (lower surface in FIG. 4) of the ceramic substrate 11 , a copper plate 43 to be the metal layer 13 is laminated with a bonding material 45 interposed therebetween.
  • the heating temperature in the pressurizing and heating step S03 is preferably in the range of 800° C. or higher and 850° C. or lower.
  • the total temperature integral value in the heating step from 780° C. to the heating temperature and the holding step at the heating temperature is preferably within the range of 7° C. ⁇ h or more and 80° C. ⁇ h or less.
  • the pressure load in the pressurization and heating step S03 is preferably within the range of 0.029 MPa or more and 2.94 MPa or less.
  • the degree of vacuum in the pressurizing and heating step S03 is preferably in the range of 1 ⁇ 10 ⁇ 6 Pa or more and 5 ⁇ 10 ⁇ 2 Pa or less.
  • the cooling rate in this cooling step S04 is preferably within the range of 2° C./min or more and 20° C./min or less.
  • the cooling rate here is the cooling rate from the heating temperature to 780° C., which is the Ag—Cu eutectic temperature.
  • the insulated circuit board 10 of the present embodiment is manufactured through the bonding material disposing step S01, the laminating step S02, the pressurizing and heating step S03, and the cooling step S04.
  • Heat-sink bonding step S05 Next, the heat sink 5 is bonded to the other side of the metal layer 13 of the insulated circuit board 10 .
  • the insulating circuit board 10 and the heat sink 5 are laminated with a solder material interposed therebetween and placed in a heating furnace.
  • semiconductor element bonding step S06 Next, the semiconductor element 3 is soldered to one surface of the circuit layer 12 of the insulating circuit board 10 .
  • the power module 1 shown in FIG. 1 is produced by the above-described steps.
  • the active metal compound layer of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 The maximum reaching distance L A from 21A and the maximum reaching distance L B of the active metal diffusion region 23B in the central region B of the circuit layer 12 and the metal layer 13 from the active metal compound layer 21B are within a range of 20 ⁇ m or more and 80 ⁇ m or less. Therefore, the ceramic substrate 11, the circuit layer 12, and the metal layer 13 are strongly bonded by the active metal, and hardening of the bonded interface is suppressed.
  • the maximum thickness of the active metal compound layers 21 (21A, 21B) in the active metal diffusion regions 23 (23A, 23B) is increased.
  • the reaching distances L A and L B are preferably 25 ⁇ m or more, more preferably 35 ⁇ m or more.
  • the maximum reaching distance L A of the active metal diffusion regions 23 (23A, 23B) from the active metal compound layers 21 (21A, 21B), LB is preferably 75 ⁇ m or less, more preferably 65 ⁇ m or less.
  • the maximum reaching distance LA of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 and the maximum reaching distance of the active metal diffusion region 23B in the central region B of the circuit layer 12 and the metal layer 13 Since the difference from LB is set to 10 ⁇ m or less, it is possible to suppress the peripheral edge region A of the circuit layer 12 and the metal layer 13 from becoming relatively hard at the bonding interface, and the ceramic substrate 11 under thermal cycle load. Cracking can be suppressed, and the thermal cycle reliability is excellent.
  • the maximum reaching distance L A of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 and the central portion of the circuit layer 12 and the metal layer 13 is preferably 8 ⁇ m or less, more preferably 6 ⁇ m or less.
  • the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1A formed in the central region B of the circuit layer 12 and the metal layer 13 When the thickness t1B of the applied active metal compound layer 21B is in the range of 0.05 ⁇ m or more and 1.2 ⁇ m or less, the ceramic substrate 11, the circuit layer 12 and the metal layer 13 are reliably bonded by the active metal. In addition, hardening of the bonding interface is further suppressed.
  • the thickness t1 of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 , and the thickness t1B of the active metal compound layer 21B formed in the central region B of the circuit layer 12 and the metal layer 13 is preferably 0.08 ⁇ m or more, more preferably 0.15 ⁇ m or more. preferable.
  • the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1 A of the circuit layer 12 and the thickness t1B of the active metal compound layer 21B formed in the central region B of the metal layer 13 is preferably 1.0 ⁇ m or less, more preferably 0.6 ⁇ m or less.
  • the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1 A formed in the central region B of the circuit layer 12 and the metal layer 13 When the ratio t1A / t1B of the thickness t1B of the active metal compound layer 21B is in the range of 0.7 or more and 1.4 or less, the peripheral edge portions of the circuit layer 12 and the metal layer 13 There is no large difference in the hardness of the bonding interface between the region A and the central region B, and cracking of the ceramic substrate 11 under thermal cycle load can be further suppressed.
  • the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13, and , the ratio t1A / t1B of the thickness t1B of the active metal compound layer 21B formed in the central region B of the circuit layer 12 and the metal layer 13 is in the range of 0.8 or more and 1.2 or less. is more preferable, and more preferably within the range of 0.9 or more and 1.1 or less.
  • the thickness t2 A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13, and the thickness t2 A of the central region B of the circuit layer 12 and the metal layer 13 When the thickness t2B of the formed Ag—Cu alloy layer 22B is in the range of 1 ⁇ m or more and 30 ⁇ m or less, the Ag of the bonding material 45, which will be described later, and the circuit layer 12 and the metal layer 13 are sufficiently As a result, the ceramic substrate 11, the circuit layer 12 and the metal layer 13 are reliably and strongly bonded together, and hardening of the bonding interface is further suppressed.
  • the thickness t2 A and the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the circuit layer 12 and the metal layer 13 are preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more. Further, in order to further suppress the joining interface from becoming harder than necessary, the thickness t2 A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the circuit The thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the layer 12 and the metal layer 13 is preferably 25 ⁇ m or less, more preferably 15 ⁇ m or less.
  • the thickness t2A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t2A formed in the central region B of the circuit layer 12 and the metal layer 13 When the ratio t2A / t2B to the thickness t2B of the Ag--Cu alloy layer 22B is within the range of 0.7 or more and 1.4 or less, the circuit layer 12 and the metal layer 13 There is no large difference in the hardness of the joint interface between the peripheral edge region A and the central region B, and cracking of the ceramic substrate under thermal cycle load can be further suppressed.
  • the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 has a thickness t2 A and , the ratio t2A / t2B of the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the circuit layer 12 and the metal layer 13 is within the range of 0.8 or more and 1.2 or less. It is more preferable to make it within the range of 0.9 or more and 1.1 or less.
  • a power module is configured by mounting a semiconductor element on an insulated circuit board, but the present invention is not limited to this.
  • an LED module may be configured by mounting an LED element on the circuit layer of the insulating circuit board, or a thermoelectric module may be configured by mounting a thermoelectric element on the circuit layer of the insulating circuit board.
  • the ceramic substrate is made of aluminum nitride ( AlN).
  • other ceramic substrates such as silicon nitride (Si 3 N 4 ) may be used.
  • Ti was used as an example of the active metal contained in the bonding material. It suffices if it contains the above active metals. These active metals may be contained as hydrides.
  • the bonding material to be applied at the periphery and center of the copper plate are different to control the maximum reach L A of the active metal diffusion region in the peripheral region of the circuit layer and the metal layer and the maximum reach L B of the active metal diffusion region in the central region of the circuit layer and the metal layer.
  • the specific surface area (BET value) of Ag powder contained in the bonding material it is possible to control the aforementioned maximum reaching distance. That is, when the specific surface area of the Ag powder is small, the sinterability of the paste-like bonding material becomes high, the liquid phase is likely to occur in the pressurization and heating process, the diffusion of the active metal is promoted, and the maximum reach distance described above is increased. becomes longer. On the other hand, when the specific surface area of the Ag powder is large, the sinterability of the paste-like bonding material becomes low, making it difficult to generate a liquid phase in the pressurization and heating processes, suppressing the diffusion of the active metal, and increasing the maximum reach distance described above. becomes shorter.
  • bonding materials containing different types and amounts of active metals may be used to separately paint the peripheral edge portion and the central portion of the copper plate.
  • the circuit layer was described as being formed by bonding a rolled plate of oxygen-free copper to a ceramic substrate, but the present invention is not limited to this, and a copper piece punched out of a copper plate is used.
  • a circuit layer may be formed by bonding to a ceramic substrate while being arranged in a circuit pattern. In this case, each copper piece should have the interface structure with the ceramic substrate as described above.
  • the bonding material is provided on the bonding surface of the copper plate, but the present invention is not limited to this, and the bonding material may be provided between the ceramic substrate and the copper plate. Alternatively, a bonding material may be provided on the bonding surface of the ceramic substrate.
  • a ceramic substrate (40 mm ⁇ 40 mm) shown in Table 1 was prepared.
  • the thickness of AlN and Al 2 O 3 was 0.635 mm, and the thickness of Si 3 N 4 was 0.32 mm.
  • a copper plate made of oxygen-free copper and having a thickness of 37 mm ⁇ 37 mm and having a thickness shown in Table 1 was prepared as a copper plate serving as a circuit layer and a metal layer.
  • a bonding material containing Ag powder having a BET value shown in Table 1 was applied to the peripheral portion of the copper plate serving as the circuit layer and the metal layer so that the target thickness after drying would be the value shown in Table 1.
  • a bonding material containing Ag powder having a BET value shown in Table 1 was applied to the central portion of the copper plate serving as the circuit layer and the metal layer so that the target thickness after drying would be the value shown in Table 1.
  • a paste material was used as the bonding material, and the amounts of Ag, Cu, and active metal were as shown in Table 1.
  • the BET value (specific surface area) of the Ag powder was measured by using AUTOSORB-1 manufactured by QUANTACHRROME, vacuum deaeration by heating at 150 ° C. for 30 minutes as pretreatment, N 2 adsorption, liquid nitrogen 77 K, BET multipoint method. It was measured.
  • a copper plate which will be the circuit layer, is laminated on one side of the ceramic substrate.
  • a copper plate serving as a metal layer was laminated on the other surface of the ceramic substrate.
  • This laminate was heated while being pressed in the lamination direction to generate an Ag—Cu liquid phase.
  • the pressure load was set to 0.294 MPa, and the temperature integral value was set as shown in Table 2. Then, by cooling the heated laminate, the copper plate serving as the circuit layer, the ceramic substrate, and the metal plate serving as the metal layer were bonded to obtain an insulated circuit substrate (copper/ceramic bonded body).
  • the active metal diffusion region, active metal compound layer, Ag-Cu alloy layer, and thermal cycle reliability were evaluated as follows.
  • Comparative Example 1 the difference between the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was set to 15 ⁇ m. , the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate is set to 12 ⁇ m, and the number of cracks generated is 200 times in the thermal cycle test.
  • Comparative Example 2 the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate is 16 ⁇ m, and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate is 19 ⁇ m. In the cycle test, cracks occurred 150 times.
  • the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate is set to be in the range of 20 ⁇ m or more and 80 ⁇ m or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 ⁇ m or less.
  • the number of times cracks occurred was 300 to 500, indicating excellent thermal cycle reliability.
  • inventive examples 4 to 6 using Si 3 N 4 as the ceramic substrate and comparative examples 3 and 4 are compared.
  • the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate was 108 ⁇ m
  • the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 102 ⁇ m.
  • the cycle test cracks occurred 1200 times.
  • the difference between the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 14 ⁇ m.
  • the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate is set to be in the range of 20 ⁇ m or more and 80 ⁇ m or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 ⁇ m or less.
  • the number of times cracks occurred exceeded 1,600 to 2,000 times, indicating excellent thermal cycle reliability.
  • inventive examples 7 and 8 using Al 2 O 3 as the ceramic substrate and comparative example 5 are compared.
  • the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate was 16 ⁇ m
  • the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 18 ⁇ m. In the test, cracks occurred 50 times.
  • the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate is set to be in the range of 20 ⁇ m or more and 80 ⁇ m or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 ⁇ m or less.
  • the number of times cracks occurred was 350 to 450, indicating excellent thermal cycle reliability.
  • the copper/ceramic bonded body and insulating circuit board of this embodiment are suitably applied to power modules, LED modules and thermoelectric modules.
  • Insulated circuit board (copper/ceramic joint) 11 Ceramic substrate (ceramic member) 12 circuit layer (copper member) 13 metal layer (copper member) 21 (21A, 21B) active metal compound layer 22 (22A, 22B) Ag—Cu alloy layer 23 (23A, 23B) active metal diffusion region

Abstract

This copper/ceramic bonded body (10) comprises a ceramic member (11) and copper members (12, 13) which are formed of copper or a copper alloy; the copper members (12, 13) and the ceramic member (11) are bonded with each other; at the bonding interfaces between the ceramic member (11) and the copper members (12, 13), an active metal compound layer (21) is formed on the ceramic member (11) side of each bonding interface; an active metal diffused region (23), which has an active metal concentration of 0.5% by mass or more, is formed on the ceramic member (11) side of each of the copper members (12, 13); the maximum reach distance LA of an active metal diffused region (23A) in a peripheral region (A) and the maximum reach distance LB of an active metal diffused region (23B) in a central region (B) are within the range from 20 µm to 80 µm; and the difference between the maximum reach distance LA and the maximum reach distance LB is 10 µm or less.

Description

銅／セラミックス接合体、および、絶縁回路基板Copper/Ceramic Bonded Body and Insulated Circuit Board
　この発明は、銅又は銅合金からなる銅部材と、セラミックス部材とが接合されてなる銅／セラミックス接合体、および、セラミックス基板の表面に、銅又は銅合金からなる銅板が接合されてなる絶縁回路基板に関するものである。
　本願は、２０２１年７月１６日に、日本に出願された特願２０２１－１１７９４９号に基づき優先権を主張し、その内容をここに援用する。 The present invention provides a copper/ceramic bonded body in which a copper member made of copper or a copper alloy and a ceramic member are joined together, and an insulating circuit in which a copper plate made of copper or a copper alloy is joined to the surface of a ceramic substrate. It relates to substrates.
This application claims priority based on Japanese Patent Application No. 2021-117949 filed in Japan on July 16, 2021, the content of which is incorporated herein.
　パワーモジュール、ＬＥＤモジュールおよび熱電モジュールにおいては、絶縁層の一方の面に導電材料からなる回路層を形成した絶縁回路基板に、パワー半導体素子、ＬＥＤ素子および熱電素子が接合された構造とされている。
　例えば、風力発電、電気自動車、ハイブリッド自動車等を制御するために用いられる大電力制御用のパワー半導体素子は、動作時の発熱量が多いことから、これを搭載する基板としては、セラミックス基板と、このセラミックス基板の一方の面に導電性の優れた金属板を接合して形成した回路層と、セラミックス基板の他方の面に金属板を接合して形成した放熱用の金属層と、を備えた絶縁回路基板が、従来から広く用いられている。 A power module, an LED module, and a thermoelectric module have a structure in which a power semiconductor element, an LED element, and a thermoelectric element are joined to an insulating circuit board in which a circuit layer made of a conductive material is formed on one side of an insulating layer. .
For example, power semiconductor elements for high power control used to control wind power generation, electric vehicles, hybrid vehicles, etc. generate a large amount of heat during operation. A circuit layer formed by bonding a metal plate having excellent conductivity to one surface of the ceramic substrate, and a metal layer for heat dissipation formed by bonding a metal plate to the other surface of the ceramic substrate. Insulated circuit boards have been widely used in the past.
　例えば、特許文献１には、セラミックス基板の一方の面および他方の面に、銅板を接合することにより回路層および金属層を形成した絶縁回路基板が提案されている。この特許文献１においては、セラミックス基板の一方の面および他方の面に、Ａｇ－Ｃｕ－Ｔｉ系ろう材を介在させて銅板を配置し、加熱処理を行うことにより銅板が接合されている（いわゆる活性金属ろう付け法）。 For example, Patent Document 1 proposes an insulated circuit board in which a circuit layer and a metal layer are formed by bonding copper plates to one side and the other side of a ceramic substrate. In this patent document 1, copper plates are arranged on one surface and the other surface of a ceramic substrate with an Ag—Cu—Ti brazing material interposed therebetween, and the copper plates are joined by heat treatment (so-called active metal brazing method).
　また、特許文献２においては、銅又は銅合金からなる銅板と、ＡｌＮ又はＡｌ２Ｏ３からなるセラミックス基板とが、ＡｇおよびＴｉを含む接合材を用いて接合されたパワーモジュール用基板が提案されている。
　さらに、特許文献３には、銅又は銅合金からなる銅板と、窒化ケイ素からなるセラミックス基板とが、ＡｇおよびＴｉを含む接合材を用いて接合されたパワーモジュール用基板が提案されている。
　前述のように、Ｔｉを含む接合材を用いて銅板とセラミックス基板とを接合した場合には、活性金属であるＴｉがセラミックス基板と反応することにより、接合材の濡れ性が向上し、銅板とセラミックス基板との接合強度が向上することになる。 Patent Document 2 proposes a power module substrate in which a copper plate made of copper or a copper alloy and a ceramic substrate made of AlN or Al 2 O 3 are bonded using a bonding material containing Ag and Ti. ing.
Furthermore, Patent Document 3 proposes a power module substrate in which a copper plate made of copper or a copper alloy and a ceramic substrate made of silicon nitride are bonded using a bonding material containing Ag and Ti.
As described above, when a copper plate and a ceramic substrate are bonded using a bonding material containing Ti, Ti, which is an active metal, reacts with the ceramic substrate, thereby improving the wettability of the bonding material and the copper plate. The bonding strength with the ceramic substrate is improved.
　ところで、最近では、絶縁回路基板に搭載される半導体素子の発熱温度が高くなる傾向にあり、絶縁回路基板には、従来にも増して、厳しい冷熱サイクルに耐えることができる冷熱サイクル信頼性が求められている。
　ここで、前述のように、Ｔｉを含む接合材を用いて銅板とセラミックス基板とを接合した場合には、銅板側に活性金属であるＴｉが拡散し、ＣｕとＴｉを含む金属間化合物が析出することで、接合界面近傍が硬くなり、冷熱サイクル負荷時にセラミックス部材に割れが生じ、冷熱サイクル信頼性が低下するおそれがあった。 By the way, recently, the heat generation temperature of the semiconductor elements mounted on the insulated circuit board tends to be higher, and the insulated circuit board is required to have higher cooling/heating cycle reliability to withstand severe cooling/heating cycles. It is
Here, as described above, when a copper plate and a ceramic substrate are bonded using a bonding material containing Ti, Ti, which is an active metal, diffuses into the copper plate side, and an intermetallic compound containing Cu and Ti precipitates. As a result, the vicinity of the joint interface becomes hard, cracks may occur in the ceramic member during thermal cycle loading, and there is a risk of deterioration in thermal cycle reliability.
特許第３２１１８５６号公報Japanese Patent No. 3211856 特許第５７５７３５９号公報Japanese Patent No. 5757359 特開２０１８－００８８６９号公報JP 2018-008869 A
　この発明は、前述した事情に鑑みてなされたものであって、厳しい冷熱サイクルを負荷した場合であっても、セラミックス部材における割れの発生を抑制でき、冷熱サイクル信頼性に優れた銅／セラミックス接合体、および、この銅／セラミックス接合体からなる絶縁回路基板を提供することを目的とする。 The present invention has been made in view of the above-mentioned circumstances. It is an object of the present invention to provide an insulated circuit board made of this copper/ceramic bonded body.
　前述の課題を解決するために、本発明者らが鋭意検討した結果、セラミックス部材と銅部材とを活性金属を含む接合材を用いて接合する際に、接合時に生成した液相が銅部材の中央部から周縁部側に排斥され、銅部材の周縁部に活性金属が相対的に多く存在することになり、セラミックス部材と銅部材との接合界面において、銅部材の周縁部領域が、中央部領域に比べて硬くなる傾向があることが分かった。そして、冷熱サイクル負荷時に、接合界面において硬い銅部材の周縁部領域に応力が集中し、セラミックス部材の割れが生じやすくなるとの知見を得た。 In order to solve the above-mentioned problems, the inventors of the present invention conducted intensive studies, and found that when a ceramic member and a copper member are joined using a joining material containing an active metal, the liquid phase generated during joining is The active metal is repelled from the central portion to the peripheral edge portion side, and a relatively large amount of active metal exists in the peripheral edge portion of the copper member. It was found that there is a tendency to be harder than the region. Then, the inventors have found that stress concentrates on the peripheral edge region of the hard copper member at the bonding interface during a thermal cycle load, and cracking of the ceramic member is likely to occur.
　本発明は、前述の知見を基になされたものであって、本発明の一態様に係る銅／セラミックス接合体は、銅又は銅合金からなる銅部材と、セラミックス部材とが接合されてなる銅／セラミックス接合体であって、前記セラミックス部材と前記銅部材との接合界面において、前記セラミックス部材側には活性金属化合物層が形成されており、前記銅部材のうち前記セラミックス部材側には、活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆ）が前記セラミックス部材側から前記銅部材側へと拡散することにより、前記銅部材中の前記活性金属の濃度が０．５質量％以上である活性金属拡散領域が形成されており、前記銅部材の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＡおよび前記銅部材の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、前記銅部材の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅部材の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下であることを特徴としている。
　銅／セラミックス接合体は、前記銅部材と、前記セラミックス部材とを有し、前記銅部材と前記セラミックス部材とが接合されていると言うこともできる。 The present invention has been made based on the above findings, and a copper/ceramic joined body according to one aspect of the present invention is a copper member obtained by joining a copper member made of copper or a copper alloy and a ceramic member. / A ceramic bonded body, wherein an active metal compound layer is formed on the ceramic member side at the bonding interface between the ceramic member and the copper member, and the active metal compound layer is formed on the ceramic member side of the copper member. An active metal diffusion region in which the concentration of the active metal in the copper member is 0.5% by mass or more by diffusing metals (Ti, Zr, Nb, Hf) from the ceramic member side to the copper member side. is formed, and the maximum reaching distance LA from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper member and the active metal of the active metal diffusion region in the central region of the copper member The maximum reachable distance L B from the compound layer is in the range of 20 μm or more and 80 μm or less, and the maximum reach distance L A of the active metal diffusion region in the peripheral region of the copper member and the central portion of the copper member The difference from the maximum reaching distance LB of the active metal diffusion region in the region is 10 μm or less.
It can also be said that the copper/ceramic joined body has the copper member and the ceramic member, and the copper member and the ceramic member are joined together.
　本発明の一態様に係る銅／セラミックス接合体によれば、前記銅部材の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＡおよび前記銅部材の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされているので、活性金属によってセラミックス部材と銅部材とが強固に接合されているとともに、接合界面が硬くなることが抑制される。
　そして、前記銅部材の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅部材の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下とされているので、接合界面において、銅部材の周縁部領域が相対的に硬くなることが抑制され、冷熱サイクル負荷時におけるセラミックス部材の割れの発生を抑制でき、冷熱サイクル信頼性に優れている。 According to the copper/ceramic joined body according to one aspect of the present invention, the maximum reaching distance LA from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper member and the central portion of the copper member Since the maximum reachable distance LB from the active metal compound layer of the active metal diffusion region in the region is in the range of 20 μm or more and 80 μm or less, the ceramic member and the copper member are firmly bonded by the active metal. In addition, hardening of the bonding interface is suppressed.
The difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper member and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper member is 10 μm or less. Therefore, it is possible to suppress the peripheral region of the copper member from becoming relatively hard at the joint interface, suppress the occurrence of cracks in the ceramic member under thermal cycle load, and have excellent thermal cycle reliability. .
　ここで、本発明の一態様に係る銅／セラミックス接合体においては、前記銅部材の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅部材の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされ、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされていることが好ましい。
　この場合、前記銅部材の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅部材の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされているので、活性金属によってセラミックス部材と銅部材とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。
　そして、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされているので、前記銅部材の周縁部領域と中央部領域とで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス部材の割れの発生をさらに抑制することができる。 Here, in the copper/ceramic bonded body according to one aspect of the present invention, the thickness t1A of the active metal compound layer formed in the peripheral region of the copper member and the thickness t1A formed in the central region of the copper member In addition, the thickness t1B of the active metal compound layer is in the range of 0.05 μm or more and 1.2 μm or less, and the thickness ratio t1A / t1B is in the range of 0.7 or more and 1.4 or less. is preferred.
In this case, the thickness t1A of the active metal compound layer formed in the peripheral region of the copper member and the thickness t1B of the active metal compound layer formed in the central region of the copper member are 0.05 μm. Since the thickness is within the range of 1.2 μm or less, the ceramic member and the copper member are reliably and strongly bonded by the active metal, and hardening of the bonding interface is further suppressed.
Further, since the thickness ratio t1A / t1B is within the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper member. Therefore, it is possible to further suppress the occurrence of cracks in the ceramic member under thermal cycle load.
　また、本発明の一態様に係る銅／セラミックス接合体においては、前記セラミックス部材と前記銅部材との接合界面において、前記銅部材側にはＡｇ－Ｃｕ合金層が形成されており、前記銅部材の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅部材の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされ、厚さ比ｔ２Ａ／ｔ２Ｂが０．７以上１．４以下の範囲内とされていることが好ましい。
　この場合、前記銅部材の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅部材の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされているので、接合材のＡｇが銅部材と十分に反応してセラミックス部材と銅部材とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。
　そして、厚さ比ｔ２Ａ／ｔ２Ｂが、０．７以上１．４以下の範囲内とされているので、前記銅部材の周縁部領域と中央部領域とで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス部材の割れの発生をさらに抑制することができる。 Further, in the copper/ceramic bonded body according to one aspect of the present invention, an Ag—Cu alloy layer is formed on the copper member side at the bonding interface between the ceramic member and the copper member, and the copper member The thickness t2 A of the Ag--Cu alloy layer formed in the peripheral region of the and the thickness t2 B of the Ag--Cu alloy layer formed in the central region of the copper member are in the range of 1 μm or more and 30 μm or less. and the thickness ratio t2A / t2B is preferably in the range of 0.7 or more and 1.4 or less.
In this case, the thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper member and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper member are 1 μm. Since the thickness is within the range of 30 μm or less, the Ag of the bonding material sufficiently reacts with the copper member, so that the ceramic member and the copper member are reliably and firmly bonded, and the bonding interface is further hardened. Suppressed.
Since the thickness ratio t2A / t2B is in the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper member. is not generated, and the occurrence of cracks in the ceramic member under thermal cycle load can be further suppressed.
　本発明の一態様に係る絶縁回路基板は、セラミックス基板の表面に、銅又は銅合金からなる銅板が接合されてなる絶縁回路基板であって、前記セラミックス基板と前記銅板との接合界面において、前記セラミックス基板側には活性金属化合物層が形成されており、前記銅板のうち前記セラミックス基板側には、活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆ）が前記セラミックス基板側から前記銅板側へと拡散することにより、前記銅板中の前記活性金属の濃度が０．５質量％以上である活性金属拡散領域が形成されており、前記銅板の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＡおよび前記銅板の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、前記銅板の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅板の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下であることを特徴としている。
　絶縁回路基板は、前記セラミックス基板と、前記銅板とを有し、前記セラミックス基板の表面に前記銅板が接合されていると言うこともできる。 An insulated circuit board according to an aspect of the present invention is an insulated circuit board in which a copper plate made of copper or a copper alloy is bonded to a surface of a ceramic substrate, wherein the bonding interface between the ceramic substrate and the copper plate includes: An active metal compound layer is formed on the ceramic substrate side, and active metals (Ti, Zr, Nb, Hf) diffuse from the ceramic substrate side to the copper plate side on the ceramic substrate side of the copper plate. As a result, an active metal diffusion region in which the concentration of the active metal in the copper plate is 0.5% by mass or more is formed, and from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the maximum reachable distance LB of the active metal diffusion region from the active metal compound layer in the central region of the copper plate are within the range of 20 μm or more and 80 μm or less, and the copper plate The difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper plate is 10 μm or less. .
It can also be said that the insulating circuit board has the ceramic substrate and the copper plate, and the copper plate is joined to the surface of the ceramic substrate.
　本発明の一態様に係る絶縁回路基板によれば、前記銅板の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＡおよび前記銅板の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの前記最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされているので、活性金属によってセラミックス基板と銅板とが強固に接合されているとともに、接合界面が硬くなることが抑制される。
　そして、前記銅板の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅板の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下とされているので、接合界面において、前記銅板の周縁部領域が相対的に硬くなることを抑制でき、冷熱サイクル負荷時におけるセラミックス基板の割れの発生を抑制でき、冷熱サイクル信頼性に優れている。 According to the insulated circuit board according to one aspect of the present invention, the maximum reaching distance LA from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active distance in the central region of the copper plate Since the maximum reachable distance L B of the metal diffusion region from the active metal compound layer is in the range of 20 μm or more and 80 μm or less, the ceramic substrate and the copper plate are firmly bonded by the active metal, and the bonding interface is hardening is suppressed.
The difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper plate is 10 μm or less. Therefore, it is possible to suppress the peripheral region of the copper plate from becoming relatively hard at the joint interface, suppress the occurrence of cracks in the ceramic substrate under thermal cycle loads, and have excellent thermal cycle reliability.
　ここで、本発明の一態様に係る絶縁回路基板においては、前記銅板の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅板の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされ、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされていることが好ましい。
　この場合、前記銅板の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅板の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされているので、活性金属によってセラミックス基板と銅板とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。
　そして、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされているので、前記銅板の周縁部領域と中央部領域とで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス基板の割れの発生をさらに抑制することが可能となる。 Here, in the insulated circuit board according to one aspect of the present invention, the thickness t1A of the active metal compound layer formed in the peripheral region of the copper plate and the active metal layer formed in the central region of the copper plate It is preferable that the thickness t1B of the compound layer is in the range of 0.05 μm or more and 1.2 μm or less, and the thickness ratio t1A / t1B is in the range of 0.7 or more and 1.4 or less.
In this case, the thickness t1A of the active metal compound layer formed in the peripheral region of the copper plate and the thickness t1B of the active metal compound layer formed in the central region of the copper plate are 0.05 μm or more. Since the thickness is within the range of 0.2 μm or less, the ceramic substrate and the copper plate are reliably and strongly bonded by the active metal, and hardening of the bonding interface is further suppressed.
Further, since the thickness ratio t1A / t1B is within the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper plate. Moreover, it is possible to further suppress the occurrence of cracks in the ceramic substrate under thermal cycle load.
　また、本発明の一態様に係る絶縁回路基板においては、前記セラミックス基板と前記銅板との接合界面において、前記銅板側にはＡｇ－Ｃｕ合金層が形成されており、前記銅板の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅板の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされ、厚さ比ｔ２Ａ／ｔ２Ｂが０．７以上１．４以下の範囲内とされていることが好ましい。
　この場合、前記銅板の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅板の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされているので、接合材のＡｇが銅板と十分に反応してセラミックス基板と銅板とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。
　そして、厚さ比ｔ２Ａ／ｔ２Ｂが、０．７以上１．４以下の範囲内とされているので前記銅板の周縁部領域と中央部領域とで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス基板の割れの発生をさらに抑制することができる。 Further, in the insulated circuit board according to one aspect of the present invention, an Ag—Cu alloy layer is formed on the side of the copper plate at the bonding interface between the ceramic substrate and the copper plate, and in the peripheral region of the copper plate The thickness t2 A of the Ag—Cu alloy layer formed and the thickness t2 B of the Ag—Cu alloy layer formed in the central region of the copper plate are in the range of 1 μm or more and 30 μm or less, and the thickness ratio It is preferable that t2A / t2B is in the range of 0.7 or more and 1.4 or less.
In this case, the thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper plate and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper plate are 1 μm or more and 30 μm. Since it is within the following range, the Ag of the bonding material sufficiently reacts with the copper plate, and the ceramic substrate and the copper plate are reliably and strongly bonded, and hardening of the bonding interface is further suppressed.
Since the thickness ratio t2A / t2B is in the range of 0.7 or more and 1.4 or less, there is a large difference in the hardness of the bonding interface between the peripheral region and the central region of the copper plate. In addition, it is possible to further suppress the occurrence of cracks in the ceramic substrate under a thermal cycle load.
　本発明の一態様によれば、厳しい冷熱サイクルを負荷した場合であっても、セラミックス部材における割れの発生を抑制でき、冷熱サイクル信頼性に優れた銅／セラミックス接合体、および、この銅／セラミックス接合体からなる絶縁回路基板を提供することができる。 According to one aspect of the present invention, a copper/ceramic joint that can suppress the occurrence of cracks in a ceramic member even when a severe thermal cycle is applied and has excellent thermal cycle reliability, and the copper/ceramic It is possible to provide an insulated circuit board made of a bonded body.
本発明の実施形態に係る絶縁回路基板を用いたパワーモジュールの概略説明図である。1 is a schematic explanatory diagram of a power module using an insulated circuit board according to an embodiment of the present invention; FIG. 本発明の実施形態に係る絶縁回路基板の回路層および金属層とセラミックス基板との接合界面の拡大説明図である。（ａ）が回路層および金属層の周縁部領域と中央部領域の説明図、（ｂ）が周縁部領域、（ｃ）が中央部領域である。FIG. 2 is an enlarged explanatory view of a bonding interface between a circuit layer and a metal layer of an insulated circuit board and a ceramic substrate according to an embodiment of the present invention; (a) is an explanatory diagram of the peripheral region and the central region of the circuit layer and the metal layer, (b) is the peripheral region, and (c) is the central region. 本発明の実施形態に係る絶縁回路基板の製造方法のフロー図である。1 is a flowchart of a method for manufacturing an insulated circuit board according to an embodiment of the present invention; FIG. 本発明の実施形態に係る絶縁回路基板の製造方法の概略説明図である。It is a schematic explanatory drawing of the manufacturing method of the insulation circuit board which concerns on embodiment of this invention. 本発明の実施形態に係る絶縁回路基板の製造方法における接合材配設工程の説明図である。FIG. 4 is an explanatory diagram of a bonding material disposing step in the method of manufacturing an insulated circuit board according to the embodiment of the present invention;
　以下に、本発明の実施形態について添付した図面を参照して説明する。
　本実施形態に係る銅／セラミックス接合体は、セラミックスからなるセラミックス部材としてのセラミックス基板１１と、銅又は銅合金からなる銅部材としての銅板４２（回路層１２）および銅板４３（金属層１３）とが接合されてなる絶縁回路基板１０である。図１に、本実施形態である絶縁回路基板１０を備えたパワーモジュール１を示す。 Embodiments of the present invention will be described below with reference to the accompanying drawings.
The copper/ceramic bonded body according to the present embodiment includes a ceramic substrate 11 as a ceramic member made of ceramics, and a copper plate 42 (circuit layer 12) and a copper plate 43 (metal layer 13) as copper members made of copper or a copper alloy. is an insulating circuit board 10 formed by bonding the . FIG. 1 shows a power module 1 having an insulated circuit board 10 according to this embodiment.
　このパワーモジュール１は、回路層１２および金属層１３が配設された絶縁回路基板１０と、回路層１２の一方の面（図１において上面）に接合層２を介して接合された半導体素子３と、金属層１３の他方側（図１において下側）に配置されたヒートシンク５と、を備えている。 This power module 1 includes an insulating circuit board 10 on which a circuit layer 12 and a metal layer 13 are arranged, and a semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the circuit layer 12 via a bonding layer 2. and a heat sink 5 arranged on the other side (lower side in FIG. 1) of the metal layer 13 .
　半導体素子３は、Ｓｉ等の半導体材料で構成されている。この半導体素子３と回路層１２は、接合層２を介して接合されている。
　接合層２は、例えばＳｎ－Ａｇ系、Ｓｎ－Ｉｎ系、若しくはＳｎ－Ａｇ－Ｃｕ系のはんだ材で構成されている。 The semiconductor element 3 is made of a semiconductor material such as Si. The semiconductor element 3 and the circuit layer 12 are bonded via the bonding layer 2 .
The bonding layer 2 is made of, for example, a Sn--Ag-based, Sn--In-based, or Sn--Ag--Cu-based solder material.
　ヒートシンク５は、前述の絶縁回路基板１０からの熱を放散するためのものである。このヒートシンク５は、銅又は銅合金で構成されており、本実施形態ではりん脱酸銅で構成されている。このヒートシンク５には、冷却用の流体が流れるための流路が設けられている。
　なお、本実施形態においては、ヒートシンク５と金属層１３とが、はんだ材からなるはんだ層７によって接合されている。このはんだ層７は、例えばＳｎ－Ａｇ系、Ｓｎ－Ｉｎ系、若しくはＳｎ－Ａｇ－Ｃｕ系のはんだ材で構成されている。 The heat sink 5 is for dissipating heat from the insulating circuit board 10 described above. The heat sink 5 is made of copper or a copper alloy, and is made of phosphorus-deoxidized copper in this embodiment. The heat sink 5 is provided with a channel through which cooling fluid flows.
In addition, in this embodiment, the heat sink 5 and the metal layer 13 are joined by a solder layer 7 made of a solder material. The solder layer 7 is made of, for example, a Sn--Ag-based, Sn--In-based, or Sn--Ag--Cu-based solder material.
　そして、本実施形態である絶縁回路基板１０は、図１に示すように、セラミックス基板１１と、このセラミックス基板１１の一方の面（図１において上面）に配設された回路層１２と、セラミックス基板１１の他方の面（図１において下面）に配設された金属層１３と、を備えている。 As shown in FIG. 1, the insulating circuit board 10 of the present embodiment includes a ceramic substrate 11, a circuit layer 12 provided on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and a ceramic substrate. and a metal layer 13 disposed on the other surface (lower surface in FIG. 1) of the substrate 11 .
　セラミックス基板１１は、絶縁性および放熱性に優れた窒化ケイ素（Ｓｉ３Ｎ４）、窒化アルミニウム（ＡｌＮ）、アルミナ（Ａｌ２Ｏ３）等のセラミックスで構成されている。本実施形態では、セラミックス基板１１は、特に放熱性の優れた窒化アルミニウム（ＡｌＮ）で構成されている。また、セラミックス基板１１の厚さは、例えば、０．２ｍｍ以上１．５ｍｍ以下の範囲内に設定されており、本実施形態では、０．６３５ｍｍに設定されている。 The ceramics substrate 11 is made of ceramics such as silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), alumina (Al 2 O 3 ), etc., which are excellent in insulation and heat dissipation. In this embodiment, the ceramic substrate 11 is made of aluminum nitride (AlN), which has excellent heat dissipation properties. The thickness of the ceramic substrate 11 is set within a range of, for example, 0.2 mm or more and 1.5 mm or less, and is set to 0.635 mm in this embodiment.
　回路層１２は、図４に示すように、セラミックス基板１１の一方の面（図４において上面）に、銅又は銅合金からなる銅板４２が接合されることにより形成されている。
　本実施形態においては、回路層１２は、無酸素銅の圧延板がセラミックス基板１１に接合されることで形成されている。
　なお、回路層１２となる銅板４２の厚さは０．１ｍｍ以上２．０ｍｍ以下の範囲内に設定されており、本実施形態では、０．６ｍｍに設定されている。 As shown in FIG. 4, the circuit layer 12 is formed by bonding a copper plate 42 made of copper or a copper alloy to one surface (upper surface in FIG. 4) of the ceramic substrate 11. As shown in FIG.
In this embodiment, the circuit layer 12 is formed by bonding a rolled plate of oxygen-free copper to the ceramic substrate 11 .
The thickness of the copper plate 42 that forms the circuit layer 12 is set within a range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in this embodiment.
　金属層１３は、図４に示すように、セラミックス基板１１の他方の面（図４において下面）に、銅又は銅合金からなる銅板４３が接合されることにより形成されている。
　本実施形態においては、金属層１３は、無酸素銅の圧延板がセラミックス基板１１に接合されることで形成されている。
　なお、金属層１３となる銅板４３の厚さは０．１ｍｍ以上２．０ｍｍ以下の範囲内に設定されており、本実施形態では、０．６ｍｍに設定されている。 As shown in FIG. 4, the metal layer 13 is formed by bonding a copper plate 43 made of copper or a copper alloy to the other surface of the ceramic substrate 11 (the lower surface in FIG. 4).
In this embodiment, the metal layer 13 is formed by bonding a rolled plate of oxygen-free copper to the ceramic substrate 11 .
The thickness of the copper plate 43 that forms the metal layer 13 is set within a range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in this embodiment.
　ここで、セラミックス基板１１と回路層１２および金属層１３との接合界面においては、図２に示すように、セラミックス基板１１側から順に、活性金属化合物層２１、Ａｇ－Ｃｕ合金層２２が形成されている。
　活性金属化合物層２１は、セラミックス基板１１の一部であると言うこともできる。Ａｇ－Ｃｕ合金層２２は、回路層１２および金属層１３の一部であると言うこともできる。このため、セラミックス基板１１と回路層１２および金属層１３（銅板４２，４３）との接合界面は、活性金属化合物層２１とＡｇ－Ｃｕ合金層２２との界面である。Ａｇ－Ｃｕ合金層２２を有しない場合、セラミックス基板１１と回路層１２および金属層１３（銅板４２，４３）との接合界面は、活性金属化合物層２１と回路層１２および金属層１３（銅板４２，４３）との界面である。
　また、回路層１２および金属層１３においては、セラミックス基板１１との接合界面側には、活性金属（本実施形態ではＴｉ）が回路層１２側および金属層１３側へと拡散することにより、回路層１２および金属層１３における活性金属の濃度が０．５質量％以上である活性金属拡散領域２３が形成されている。 Here, as shown in FIG. 2, an active metal compound layer 21 and an Ag—Cu alloy layer 22 are formed in order from the ceramic substrate 11 side at the bonding interface between the ceramic substrate 11, the circuit layer 12 and the metal layer 13. ing.
It can also be said that the active metal compound layer 21 is part of the ceramic substrate 11 . It can also be said that the Ag—Cu alloy layer 22 is part of the circuit layer 12 and the metal layer 13 . Therefore, the bonding interface between the ceramic substrate 11 and the circuit layer 12 and metal layer 13 (copper plates 42 and 43) is the interface between the active metal compound layer 21 and the Ag--Cu alloy layer 22. FIG. Without the Ag—Cu alloy layer 22, the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13 (copper plates 42 and 43) is the active metal compound layer 21, the circuit layer 12 and the metal layer 13 (copper plate 42 , 43).
In the circuit layer 12 and the metal layer 13, the active metal (Ti in this embodiment) diffuses toward the circuit layer 12 and the metal layer 13 on the side of the bonding interface with the ceramic substrate 11, thereby forming a circuit. An active metal diffusion region 23 is formed in which the active metal concentration in the layer 12 and the metal layer 13 is 0.5 mass % or more.
　そして、本実施形態である絶縁回路基板１０においては、図２に示すように、回路層１２および金属層１３の周縁部領域Ａと中央部領域Ｂにおける界面構造について、以下のように規定されている。
　なお、本実施形態において、回路層１２および金属層１３の周縁部領域Ａは、図２（ａ）に示すように、回路層１２および金属層１３とセラミックス基板１１との積層方向に沿った断面において、回路層１２および金属層１３の幅方向端部から２０μｍ内方位置を起点としてさらに幅方向内方に２００μｍまでの領域である。
　また、回路層１２および金属層１３の中央部領域Ｂは、図２（ａ）に示すように、回路層１２および金属層１３とセラミックス基板１１との積層方向に沿った断面において、回路層１２および金属層１３の幅方向中心を含む幅方向２００μｍの領域である。 In the insulated circuit board 10 of the present embodiment, as shown in FIG. 2, the interface structure between the peripheral region A and the central region B of the circuit layer 12 and the metal layer 13 is defined as follows. there is
In this embodiment, as shown in FIG. 2A, the peripheral region A of the circuit layer 12 and the metal layer 13 is a cross section along the lamination direction of the circuit layer 12 and the metal layer 13 and the ceramic substrate 11. 2, the region extends from the widthwise end of the circuit layer 12 and the metal layer 13 to 200 μm further inward in the width direction from a position 20 μm inward from the widthwise end.
In addition, as shown in FIG. 2(a), the central region B of the circuit layer 12 and the metal layer 13 is the circuit layer 12 in the cross section along the lamination direction of the circuit layer 12 and the metal layer 13 and the ceramic substrate 11. and a region of 200 μm in the width direction including the center of the metal layer 13 in the width direction.
　ここで、図２（ｂ）に示すように、セラミックス基板１１と回路層１２および金属層１３との接合界面の周縁部領域Ａにおいては、活性金属拡散領域２３Ａの活性金属化合物層２１Ａからの最大到達距離ＬＡは、２０μｍ以上８０μｍ以下の範囲内とされている。
　また、図２（ｃ）に示すように、セラミックス基板１１と回路層１２および金属層１３との接合界面の中央部領域Ｂにおいては、活性金属拡散領域２３Ｂの活性金属化合物層２１Ｂからの最大到達距離ＬＢは、２０μｍ以上８０μｍ以下の範囲内とされている。 Here, as shown in FIG. 2B, in the peripheral region A of the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13, the maximum The reaching distance LA is in the range of 20 μm or more and 80 μm or less.
Further, as shown in FIG. 2(c), in the central region B of the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13, the maximum reach from the active metal compound layer 21B of the active metal diffusion region 23B is The distance LB is within the range of 20 μm or more and 80 μm or less.
　そして、本実施形態においては、セラミックス基板１１と回路層１２および金属層１３との接合界面の周縁部領域Ａにおける活性金属拡散領域２３Ａの最大到達距離ＬＡと、セラミックス基板１１と回路層１２および金属層１３との接合界面の中央部領域Ｂにおける活性金属拡散領域２３Ｂの最大到達距離ＬＢとの差が１０μｍ以下とされている。 In this embodiment, the maximum reaching distance LA of the active metal diffusion region 23A in the peripheral region A of the bonding interface between the ceramic substrate 11, the circuit layer 12, and the metal layer 13, the ceramic substrate 11, the circuit layer 12, and the The difference from the maximum reaching distance LB of the active metal diffusion region 23B in the central region B of the bonding interface with the metal layer 13 is 10 μm or less.
　また、本実施形態においては、セラミックス基板１１と回路層１２および金属層１３との接合界面の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、セラミックス基板１１と回路層１２および金属層１３との接合界面の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂが、０．０５μｍ以上１．２μｍ以下の範囲内とされ、これらの厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされていることが好ましい。
　ここで、活性金属化合物層２１（２１Ａ，２１Ｂ）は接合材４５で用いる活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆから選択される１種以上）の化合物からなる層である。より具体的には、セラミックス基板が窒化ケイ素（Ｓｉ３Ｎ４）、窒化アルミニウム（ＡｌＮ）からなる場合には、これらの活性金属の窒化物からなる層となり、セラミックス基板がアルミナ（Ａｌ２Ｏ３）である場合には、これらの活性金属の酸化物からなる層となる。活性金属化合物層２１（２１Ａ，２１Ｂ）は活性金属化合物の粒子が集合して形成されている。この粒子の平均粒径は１０ｎｍ以上１００ｎｍ以下である。
　なお、本実施形態では、接合材４５が活性金属としてＴｉを含有し、セラミックス基板１１が窒化アルミニウムで構成されているため、活性金属化合物層２１（２１Ａ，２１Ｂ）は、窒化チタン（ＴｉＮ）で構成される。すなわち、活性金属化合物層２１（２１Ａ，２１Ｂ）は、平均粒径が１０ｎｍ以上１００ｎｍ以下の窒化チタン（ＴｉＮ）の粒子が集合して形成されている。 In addition, in the present embodiment, the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13, and the thickness t1 A of the ceramic substrate 11 and the circuit layer 13 The thickness t1B of the active metal compound layer 21B formed in the central region B of the bonding interface between the layer 12 and the metal layer 13 is in the range of 0.05 μm or more and 1.2 μm or less, and the thickness ratio It is preferable that t1A / t1B is in the range of 0.7 or more and 1.4 or less.
Here, the active metal compound layer 21 (21A, 21B) is a layer made of a compound of an active metal (at least one selected from Ti, Zr, Nb, and Hf) used in the bonding material 45. FIG. More specifically, when the ceramic substrate is made of silicon nitride (Si 3 N 4 ) or aluminum nitride (AlN), the layer becomes a nitride of these active metals, and the ceramic substrate is made of alumina (Al 2 O 3 ), the layer consists of oxides of these active metals. The active metal compound layers 21 (21A, 21B) are formed by aggregating active metal compound particles. The average particle size of these particles is 10 nm or more and 100 nm or less.
In this embodiment, since the bonding material 45 contains Ti as an active metal and the ceramic substrate 11 is made of aluminum nitride, the active metal compound layers 21 (21A, 21B) are made of titanium nitride (TiN). Configured. That is, the active metal compound layers 21 (21A, 21B) are formed by aggregation of particles of titanium nitride (TiN) having an average particle diameter of 10 nm or more and 100 nm or less.
　さらに、本実施形態においては、セラミックス基板１１と回路層１２および金属層１３との接合界面の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａと、セラミックス基板１１と回路層１２および金属層１３との接合界面の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂとの比ｔ２Ａ／ｔ２Ｂが、０．７以上１．４以下の範囲内とされていることが好ましい。
　また、Ａｇ－Ｃｕ合金層２２（２２Ａ、２２Ｂ）の厚さは、１μｍ以上３０μｍ以下とすることが好ましい。 Furthermore, in the present embodiment, the thickness t2A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13, and the thickness t2A of the ceramic substrate 11 and the circuit The ratio t2A / t2B to the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the bonding interface between the layer 12 and the metal layer 13 is in the range of 0.7 or more and 1.4 or less. preferably within.
Further, the thickness of the Ag--Cu alloy layers 22 (22A, 22B) is preferably 1 μm or more and 30 μm or less.
　以下に、本実施形態に係る絶縁回路基板１０の製造方法について、図３および図４を参照して説明する。 A method for manufacturing the insulated circuit board 10 according to the present embodiment will be described below with reference to FIGS. 3 and 4. FIG.
（接合材配設工程Ｓ０１）
　回路層１２となる銅板４２と、金属層１３となる銅板４３とを準備する。
　そして、回路層１２となる銅板４２および金属層１３となる銅板４３の接合面に、接合材４５を塗布し、乾燥させる。ペースト状の接合材４５の塗布厚さは、乾燥後で１０μｍ以上５０μｍ以下の範囲内とすることが好ましい。
　本実施形態では、スクリーン印刷によってペースト状の接合材４５を塗布する。 (Bonding Material Arranging Step S01)
A copper plate 42 to be the circuit layer 12 and a copper plate 43 to be the metal layer 13 are prepared.
Then, a bonding material 45 is applied to the bonding surfaces of the copper plate 42 to be the circuit layer 12 and the copper plate 43 to be the metal layer 13 and dried. The coating thickness of the paste-like bonding material 45 is preferably within the range of 10 μm or more and 50 μm or less after drying.
In this embodiment, the paste bonding material 45 is applied by screen printing.
　接合材４５は、Ａｇと活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆ）を含有するものとされている。本実施形態では、接合材４５として、Ａｇ－Ｔｉ系ろう材（Ａｇ－Ｃｕ－Ｔｉ系ろう材）を用いている。なお、Ａｇ－Ｔｉ系ろう材（Ａｇ－Ｃｕ－Ｔｉ系ろう材）としては、例えば、Ｃｕを０質量％以上４５質量％以下の範囲内、活性金属であるＴｉを０．５質量％以上２０質量％以下の範囲で含み、残部がＡｇおよび不可避不純物とされた組成のものを用いることが好ましい。 The bonding material 45 contains Ag and active metals (Ti, Zr, Nb, Hf). In this embodiment, as the bonding material 45, an Ag--Ti based brazing material (Ag--Cu--Ti based brazing material) is used. The Ag--Ti-based brazing material (Ag--Cu--Ti-based brazing material) contains, for example, 0% by mass or more and 45% by mass or less of Cu, and 0.5% by mass or more and 20% by mass of Ti, which is an active metal. It is preferable to use a composition having a content in the range of mass % or less, with the balance being Ag and unavoidable impurities.
　接合材４５に含まれるＡｇ粉の比表面積は、０．１５ｍ２／ｇ以上とすることが好ましく、０．２５ｍ２／ｇ以上とすることがさらに好ましく、０．４０ｍ２／ｇ以上とすることがより好ましい。一方、接合材４５に含まれるＡｇ粉の比表面積は、１．４０ｍ２／ｇ以下とすることが好ましく、１．００ｍ２／ｇ以下とすることがさらに好ましく、０．７５ｍ２／ｇ以下とすることがより好ましい。
　なお、ペースト状の接合材４５に含まれるＡｇ粉の粒径は、Ｄ１０が０．７μｍ以上３．５μｍ以下、かつ、Ｄ１００が４．５μｍ以上２３μｍ以下の範囲内であることが好ましい。Ｄ１０は、レーザー回折散乱式粒度分布測定法により測定された粒度分布において、体積基準で累積頻度が１０％になる粒径であり、Ｄ１００は体積基準で累積頻度が１００％になる粒径である。 The specific surface area of Ag powder contained in the bonding material 45 is preferably 0.15 m 2 /g or more, more preferably 0.25 m 2 /g or more, and more preferably 0.40 m 2 /g or more. is more preferred. On the other hand, the specific surface area of the Ag powder contained in the bonding material 45 is preferably 1.40 m 2 /g or less, more preferably 1.00 m 2 /g or less, and 0.75 m 2 /g or less. is more preferable.
The particle size of the Ag powder contained in the paste-like bonding material 45 preferably has a D10 of 0.7 μm or more and 3.5 μm or less and a D100 of 4.5 μm or more and 23 μm or less. D10 is the particle size at which the cumulative frequency is 10% on a volume basis in the particle size distribution measured by a laser diffraction scattering particle size distribution measurement method, and D100 is the particle size at which the cumulative frequency is 100% on a volume basis. .
　ここで、後述する加圧および加熱工程Ｓ０３において、積層方向に加圧することにより、発生した液相が銅板４２，４３の中央部から周縁部側へ排斥され、銅板４２，４３の周縁部に活性金属成分が比較的多く存在することになる。
　よって、本実施形態では、図５に示すように、回路層１２となる銅板４２および金属層１３となる銅板４３の周縁部における接合材４５Ａの塗布厚さが、回路層１２となる銅板４２および金属層１３となる銅板４３の中央部における接合材４５Ｂの塗布厚さよりも薄くなるように、接合材４５を塗布している。
　なお、回路層１２となる銅板４２および金属層１３となる銅板４３の周縁部における接合材４５Ａの塗布厚さと、中央部における接合材４５Ｂの塗布厚さの差は、５μｍ以上１５μｍ以下の範囲内とすることが好ましい。
　接合材４５Ａを塗布する周縁部は、周縁部領域を含み、かつ銅板４２，４３の表面積の１．５％～１０％の面積を有する周縁の部位であり、周縁部の線幅は最大で１ｍｍである。接合材４５Ｂを塗布する中央部は、中央部領域を含み、かつ銅板４２，４３の表面積の９０％～９８．５％の面積を有する中央の部位である。 Here, in the pressing and heating step S03 to be described later, by applying pressure in the stacking direction, the generated liquid phase is expelled from the central portion of the copper plates 42 and 43 to the peripheral portion side, and the peripheral portions of the copper plates 42 and 43 are activated. A relatively large amount of metal components will be present.
Therefore, in this embodiment, as shown in FIG. The bonding material 45 is applied so as to be thinner than the coating thickness of the bonding material 45B in the central portion of the copper plate 43 that becomes the metal layer 13 .
Note that the difference between the coating thickness of the bonding material 45A in the peripheral edge portion of the copper plate 42 serving as the circuit layer 12 and the copper plate 43 serving as the metal layer 13 and the coating thickness of the bonding material 45B in the central portion is in the range of 5 μm or more and 15 μm or less. It is preferable to
The peripheral portion to which the bonding material 45A is applied is a portion of the peripheral portion that includes the peripheral portion area and has an area of 1.5% to 10% of the surface area of the copper plates 42 and 43, and the maximum line width of the peripheral portion is 1 mm. is. The central portion to which the bonding material 45B is applied is a central portion that includes the central region and has an area of 90% to 98.5% of the surface areas of the copper plates 42 and 43 .
（積層工程Ｓ０２）
　次に、セラミックス基板１１の一方の面（図４において上面）に、接合材４５を介して回路層１２となる銅板４２を積層するとともに、セラミックス基板１１の他方の面（図４において下面）に、接合材４５を介して金属層１３となる銅板４３を積層する。 (Lamination step S02)
Next, a copper plate 42 to be the circuit layer 12 is laminated on one surface (upper surface in FIG. 4) of the ceramic substrate 11 with a bonding material 45 interposed therebetween, and on the other surface (lower surface in FIG. 4) of the ceramic substrate 11 , a copper plate 43 to be the metal layer 13 is laminated with a bonding material 45 interposed therebetween.
（加圧および加熱工程Ｓ０３）
　次に、銅板４２とセラミックス基板１１と銅板４３とを加圧した状態で、真空雰囲気の加熱炉内で加熱し、接合材４５を溶融する。
　ここで、加圧および加熱工程Ｓ０３における加熱温度は、８００℃以上８５０℃以下の範囲内とすることが好ましい。７８０℃から加熱温度までの昇温工程および加熱温度での保持工程における温度積分値の合計は、７℃・ｈ以上８０℃・ｈ以下の範囲内とすることが好ましい。
　また、加圧および加熱工程Ｓ０３における加圧荷重は、０．０２９ＭＰａ以上２．９４ＭＰａ以下の範囲内とすることが好ましい。
　さらに、加圧および加熱工程Ｓ０３における真空度は、１×１０－６Ｐａ以上５×１０－２Ｐａ以下の範囲内とすることが好ましい。 (Pressure and heating step S03)
Next, the copper plate 42, the ceramic substrate 11, and the copper plate 43 are heated in a heating furnace in a vacuum atmosphere to melt the bonding material 45 while being pressurized.
Here, the heating temperature in the pressurizing and heating step S03 is preferably in the range of 800° C. or higher and 850° C. or lower. The total temperature integral value in the heating step from 780° C. to the heating temperature and the holding step at the heating temperature is preferably within the range of 7° C.·h or more and 80° C.·h or less.
Moreover, the pressure load in the pressurization and heating step S03 is preferably within the range of 0.029 MPa or more and 2.94 MPa or less.
Further, the degree of vacuum in the pressurizing and heating step S03 is preferably in the range of 1×10 −6 Pa or more and 5×10 −2 Pa or less.
（冷却工程Ｓ０４）
　そして、加圧および加熱工程Ｓ０３の後、冷却を行うことにより、溶融した接合材４５を凝固させて、回路層１２となる銅板４２とセラミックス基板１１、セラミックス基板１１と金属層１３となる銅板４３とを接合する。
　なお、この冷却工程Ｓ０４における冷却速度は、２℃／ｍｉｎ以上２０℃／ｍｉｎ以下の範囲内とすることが好ましい。なお、ここでの冷却速度は加熱温度からＡｇ－Ｃｕ共晶温度である７８０℃までの冷却速度である。 (Cooling step S04)
After the pressurizing and heating step S03, the molten bonding material 45 is cooled to solidify, and the copper plate 42 and the ceramics substrate 11 to be the circuit layer 12, and the ceramics substrate 11 and the copper plate 43 to be the metal layer 13 are formed. Join with.
The cooling rate in this cooling step S04 is preferably within the range of 2° C./min or more and 20° C./min or less. The cooling rate here is the cooling rate from the heating temperature to 780° C., which is the Ag—Cu eutectic temperature.
　以上のように、接合材配設工程Ｓ０１、積層工程Ｓ０２、加圧および加熱工程Ｓ０３、冷却工程Ｓ０４によって、本実施形態である絶縁回路基板１０が製造されることになる。 As described above, the insulated circuit board 10 of the present embodiment is manufactured through the bonding material disposing step S01, the laminating step S02, the pressurizing and heating step S03, and the cooling step S04.
（ヒートシンク接合工程Ｓ０５）
　次に、絶縁回路基板１０の金属層１３の他方の面側にヒートシンク５を接合する。
　絶縁回路基板１０とヒートシンク５とを、はんだ材を介して積層して加熱炉に装入し、はんだ層７を介して絶縁回路基板１０とヒートシンク５とをはんだ接合する。 (Heat-sink bonding step S05)
Next, the heat sink 5 is bonded to the other side of the metal layer 13 of the insulated circuit board 10 .
The insulating circuit board 10 and the heat sink 5 are laminated with a solder material interposed therebetween and placed in a heating furnace.
（半導体素子接合工程Ｓ０６）
　次に、絶縁回路基板１０の回路層１２の一方の面に、半導体素子３をはんだ付けにより接合する。
　前述の工程により、図１に示すパワーモジュール１が製出される。 (Semiconductor element bonding step S06)
Next, the semiconductor element 3 is soldered to one surface of the circuit layer 12 of the insulating circuit board 10 .
The power module 1 shown in FIG. 1 is produced by the above-described steps.
　以上のような構成とされた本実施形態の絶縁回路基板１０（銅／セラミックス接合体）によれば、回路層１２および金属層１３の周縁部領域Ａにおける活性金属拡散領域２３Ａの活性金属化合物層２１Ａからの最大到達距離ＬＡ、および、回路層１２および金属層１３の中央部領域Ｂにおける活性金属拡散領域２３Ｂの活性金属化合物層２１Ｂからの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされているので、活性金属によってセラミックス基板１１と回路層１２および金属層１３とが強固に接合されているとともに、接合界面が硬くなることが抑制される。 According to the insulating circuit board 10 (copper/ceramic bonded body) of the present embodiment configured as described above, the active metal compound layer of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 The maximum reaching distance L A from 21A and the maximum reaching distance L B of the active metal diffusion region 23B in the central region B of the circuit layer 12 and the metal layer 13 from the active metal compound layer 21B are within a range of 20 μm or more and 80 μm or less. Therefore, the ceramic substrate 11, the circuit layer 12, and the metal layer 13 are strongly bonded by the active metal, and hardening of the bonded interface is suppressed.
　なお、セラミックス基板１１と回路層１２および金属層１３とをさらに強固に接合するためには、上述の活性金属拡散領域２３（２３Ａ，２３Ｂ）の活性金属化合物層２１（２１Ａ，２１Ｂ）からの最大到達距離ＬＡ，ＬＢを２５μｍ以上とすることが好ましく、３５μｍ以上とすることがより好ましい。
　また、接合界面が必要以上に硬くなることをさらに抑制するためには、上述の活性金属拡散領域２３（２３Ａ，２３Ｂ）の活性金属化合物層２１（２１Ａ，２１Ｂ）からの最大到達距離ＬＡ，ＬＢを７５μｍ以下とすることが好ましく、６５μｍ以下とすることがより好ましい。 In order to bond the ceramic substrate 11, the circuit layer 12 and the metal layer 13 more firmly, the maximum thickness of the active metal compound layers 21 (21A, 21B) in the active metal diffusion regions 23 (23A, 23B) is increased. The reaching distances L A and L B are preferably 25 μm or more, more preferably 35 μm or more.
Further, in order to further suppress the bonding interface from becoming unnecessarily hard, the maximum reaching distance L A of the active metal diffusion regions 23 (23A, 23B) from the active metal compound layers 21 (21A, 21B), LB is preferably 75 μm or less, more preferably 65 μm or less.
　そして、回路層１２および金属層１３の周縁部領域Ａにおける活性金属拡散領域２３Ａの最大到達距離ＬＡと、回路層１２および金属層１３の中央部領域Ｂにおける活性金属拡散領域２３Ｂの最大到達距離ＬＢとの差が１０μｍ以下とされているので、接合界面において、回路層１２および金属層１３の周縁部領域Ａが相対的に硬くなることを抑制でき、冷熱サイクル負荷時におけるセラミックス基板１１の割れの発生を抑制でき、冷熱サイクル信頼性に優れている。
　なお、冷熱サイクル信頼性をさらに向上させるためには、回路層１２および金属層１３の周縁部領域Ａにおける活性金属拡散領域２３Ａの最大到達距離ＬＡと、回路層１２および金属層１３の中央部領域Ｂにおける活性金属拡散領域２３Ｂの最大到達距離ＬＢとの差を８μｍ以下とすることが好ましく、６μｍ以下とすることがより好ましい。 The maximum reaching distance LA of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 and the maximum reaching distance of the active metal diffusion region 23B in the central region B of the circuit layer 12 and the metal layer 13 Since the difference from LB is set to 10 μm or less, it is possible to suppress the peripheral edge region A of the circuit layer 12 and the metal layer 13 from becoming relatively hard at the bonding interface, and the ceramic substrate 11 under thermal cycle load. Cracking can be suppressed, and the thermal cycle reliability is excellent.
In order to further improve the thermal cycle reliability, the maximum reaching distance L A of the active metal diffusion region 23A in the peripheral region A of the circuit layer 12 and the metal layer 13 and the central portion of the circuit layer 12 and the metal layer 13 The difference from the maximum reaching distance LB of the active metal diffusion region 23B in the region B is preferably 8 μm or less, more preferably 6 μm or less.
　また、本実施形態において、回路層１２および金属層１３の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂが、０．０５μｍ以上１．２μｍ以下の範囲内とされている場合には、活性金属によってセラミックス基板１１と回路層１２および金属層１３とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。 In addition, in the present embodiment, the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1A formed in the central region B of the circuit layer 12 and the metal layer 13 When the thickness t1B of the applied active metal compound layer 21B is in the range of 0.05 μm or more and 1.2 μm or less, the ceramic substrate 11, the circuit layer 12 and the metal layer 13 are reliably bonded by the active metal. In addition, hardening of the bonding interface is further suppressed.
　なお、セラミックス基板１１と回路層１２および金属層１３とをさらに強固に接合するためには、回路層１２および金属層１３の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂを、０．０８μｍ以上とすることが好ましく、０．１５μｍ以上とすることがより好ましい。
　また、接合界面が必要以上に硬くなることをさらに抑制するためには、回路層１２および金属層１３の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂを、１．０μｍ以下とすることが好ましく、０．６μｍ以下とすることがより好ましい。 In order to bond the ceramic substrate 11, the circuit layer 12 and the metal layer 13 more firmly, the thickness t1 of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 , and the thickness t1B of the active metal compound layer 21B formed in the central region B of the circuit layer 12 and the metal layer 13 is preferably 0.08 μm or more, more preferably 0.15 μm or more. preferable.
Further, in order to further suppress the bonding interface from becoming harder than necessary, the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1 A of the circuit layer 12 and the thickness t1B of the active metal compound layer 21B formed in the central region B of the metal layer 13 is preferably 1.0 μm or less, more preferably 0.6 μm or less.
　さらに、本実施形態において、回路層１２および金属層１３の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂの比ｔ１Ａ／ｔ１Ｂが、０．７以上１．４以下の範囲内とされている場合には、回路層１２および金属層１３の周縁部領域Ａと中央部領域Ｂとで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス基板１１の割れの発生をさらに抑制することが可能となる。 Furthermore, in the present embodiment, the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t1 A formed in the central region B of the circuit layer 12 and the metal layer 13 When the ratio t1A / t1B of the thickness t1B of the active metal compound layer 21B is in the range of 0.7 or more and 1.4 or less, the peripheral edge portions of the circuit layer 12 and the metal layer 13 There is no large difference in the hardness of the bonding interface between the region A and the central region B, and cracking of the ceramic substrate 11 under thermal cycle load can be further suppressed.
　なお、冷熱サイクル負荷時におけるセラミックス基板１１の割れの発生をさらに抑制するためには、回路層１２および金属層１３の周縁部領域Ａに形成された活性金属化合物層２１Ａの厚さｔ１Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成された活性金属化合物層２１Ｂの厚さｔ１Ｂの比ｔ１Ａ／ｔ１Ｂを、０．８以上１．２以下の範囲内とすることがさらに好ましく、０．９以上１．１以下の範囲内とすることがより好ましい。 In order to further suppress the occurrence of cracks in the ceramic substrate 11 under thermal cycle load, the thickness t1 A of the active metal compound layer 21A formed in the peripheral region A of the circuit layer 12 and the metal layer 13, and , the ratio t1A / t1B of the thickness t1B of the active metal compound layer 21B formed in the central region B of the circuit layer 12 and the metal layer 13 is in the range of 0.8 or more and 1.2 or less. is more preferable, and more preferably within the range of 0.9 or more and 1.1 or less.
　また、本実施形態において、回路層１２および金属層１３の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂが、１μｍ以上３０μｍ以下の範囲内とされている場合には、後述する接合材４５のＡｇと回路層１２および金属層１３とが十分に反応し、セラミックス基板１１と回路層１２および金属層１３とが確実に強固に接合されているとともに、接合界面が硬くなることがさらに抑制される。 Further, in the present embodiment, the thickness t2 A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13, and the thickness t2 A of the central region B of the circuit layer 12 and the metal layer 13 When the thickness t2B of the formed Ag—Cu alloy layer 22B is in the range of 1 μm or more and 30 μm or less, the Ag of the bonding material 45, which will be described later, and the circuit layer 12 and the metal layer 13 are sufficiently As a result, the ceramic substrate 11, the circuit layer 12 and the metal layer 13 are reliably and strongly bonded together, and hardening of the bonding interface is further suppressed.
　なお、セラミックス基板１１と回路層１２および金属層１３とをさらに強固に接合するためには、回路層１２および金属層１３の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂを、３μｍ以上とすることが好ましく、５μｍ以上とすることがより好ましい。
　また、接合界面が必要以上に硬くなることをさらに抑制するためには、回路層１２および金属層１３の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａ、および、回路層１２および金属層１３の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂを、２５μｍ以下とすることが好ましく、１５μｍ以下とすることがより好ましい。 In order to bond the ceramic substrate 11, the circuit layer 12 and the metal layer 13 more firmly, the thickness t2 A and the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the circuit layer 12 and the metal layer 13 are preferably 3 μm or more, more preferably 5 μm or more.
Further, in order to further suppress the joining interface from becoming harder than necessary, the thickness t2 A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the circuit The thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the layer 12 and the metal layer 13 is preferably 25 μm or less, more preferably 15 μm or less.
　さらに、本実施形態において、回路層１２および金属層１３の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａと、回路層１２および金属層１３の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂとの比ｔ２Ａ／ｔ２Ｂが、０．７以上１．４以下の範囲内とされている場合には、回路層１２および金属層１３の周縁部領域Ａと中央部領域Ｂとで接合界面の硬さに大きな差が生じず、冷熱サイクル負荷時におけるセラミックス基板の割れの発生をさらに抑制することができる。 Furthermore, in the present embodiment, the thickness t2A of the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 and the thickness t2A formed in the central region B of the circuit layer 12 and the metal layer 13 When the ratio t2A / t2B to the thickness t2B of the Ag--Cu alloy layer 22B is within the range of 0.7 or more and 1.4 or less, the circuit layer 12 and the metal layer 13 There is no large difference in the hardness of the joint interface between the peripheral edge region A and the central region B, and cracking of the ceramic substrate under thermal cycle load can be further suppressed.
　なお、冷熱サイクル負荷時におけるセラミックス基板１１の割れの発生をさらに抑制するためには、回路層１２および金属層１３の周縁部領域Ａに形成されたＡｇ－Ｃｕ合金層２２Ａの厚さｔ２Ａと、回路層１２および金属層１３の中央部領域Ｂに形成されたＡｇ－Ｃｕ合金層２２Ｂの厚さｔ２Ｂとの比ｔ２Ａ／ｔ２Ｂを、０．８以上１．２以下の範囲内とすることがさらに好ましく、０．９以上１．１以下の範囲内とすることがより好ましい。 In order to further suppress the occurrence of cracks in the ceramic substrate 11 under thermal cycle load, the Ag—Cu alloy layer 22A formed in the peripheral region A of the circuit layer 12 and the metal layer 13 has a thickness t2 A and , the ratio t2A / t2B of the thickness t2B of the Ag—Cu alloy layer 22B formed in the central region B of the circuit layer 12 and the metal layer 13 is within the range of 0.8 or more and 1.2 or less. It is more preferable to make it within the range of 0.9 or more and 1.1 or less.
　以上、本発明の実施形態について説明したが、本発明はこれに限定されることはなく、その発明の技術的要件を逸脱しない範囲で適宜変更可能である。
　例えば、本実施形態では、絶縁回路基板に半導体素子を搭載してパワーモジュールを構成するものとして説明したが、これに限定されることはない。例えば、絶縁回路基板の回路層にＬＥＤ素子を搭載してＬＥＤモジュールを構成してもよいし、絶縁回路基板の回路層に熱電素子を搭載して熱電モジュールを構成してもよい。 Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical requirements of the invention.
For example, in the present embodiment, a power module is configured by mounting a semiconductor element on an insulated circuit board, but the present invention is not limited to this. For example, an LED module may be configured by mounting an LED element on the circuit layer of the insulating circuit board, or a thermoelectric module may be configured by mounting a thermoelectric element on the circuit layer of the insulating circuit board.
　また、本実施形態の絶縁回路基板では、セラミックス基板として、窒化アルミニウム（ＡｌＮ）で構成されたものを例に挙げて説明したが、これに限定されることはなく、アルミナ（Ａｌ２Ｏ３）、窒化ケイ素（Ｓｉ３Ｎ４）等の他のセラミックス基板を用いたものであってもよい。 In addition, in the insulating circuit board of the present embodiment , the ceramic substrate is made of aluminum nitride ( AlN). , other ceramic substrates such as silicon nitride (Si 3 N 4 ) may be used.
　さらに、本実施形態では、接合材に含まれる活性金属としてＴｉを例に挙げて説明したが、これに限定されることはなく、Ｔｉ，Ｚｒ，Ｈｆ，Ｎｂから選択される１種又は２種以上の活性金属を含んでいればよい。なお、これらの活性金属は、水素化物として含まれていてもよい。 Furthermore, in the present embodiment, Ti was used as an example of the active metal contained in the bonding material. It suffices if it contains the above active metals. These active metals may be contained as hydrides.
　また、本実施形態では、銅板の周縁部および中央部における接合材の塗布厚さを調整することで、回路層および金属層の周縁部領域における活性金属拡散領域の最大到達距離ＬＡと、回路層および金属層の中央部領域における活性金属拡散領域の最大到達距離ＬＢを制御するものとして説明したが、これに限定されることはなく、銅板の周縁部および中央部で、塗布する接合材を異なるものとして、回路層および金属層の周縁部領域における活性金属拡散領域の最大到達距離ＬＡと、回路層および金属層の中央部領域における活性金属拡散領域の最大到達距離ＬＢを制御してもよい。 Further, in the present embodiment, by adjusting the coating thickness of the bonding material in the peripheral portion and the central portion of the copper plate, the maximum reaching distance L A of the active metal diffusion region in the peripheral portion region of the circuit layer and the metal layer and the circuit Although described as controlling the maximum reach L B of the active metal diffusion region in the central region of the layer and metal layer, but not limited to this, the bonding material to be applied at the periphery and center of the copper plate are different to control the maximum reach L A of the active metal diffusion region in the peripheral region of the circuit layer and the metal layer and the maximum reach L B of the active metal diffusion region in the central region of the circuit layer and the metal layer. may
　例えば、接合材に含まれるＡｇ粉の比表面積（ＢＥＴ値）を調整することにより、前述の最大到達距離を制御することができる。すなわち、Ａｇ粉の比表面積が小さいとペースト状の接合材の焼結性が高くなり、加圧および加熱工程において液相が発生し易くなり、活性金属の拡散が促進され、前述の最大到達距離が長くなる。一方、Ａｇ粉の比表面積が大きいとペースト状の接合材の焼結性が低くなり、加圧および加熱工程において液相が発生し難くなり、活性金属の拡散が抑制され、前述の最大到達距離が短くなる。
　また、含まれる活性金属の種類や量の異なる接合材を用いて、銅板の周縁部と中央部とで塗り分けてもよい。 For example, by adjusting the specific surface area (BET value) of Ag powder contained in the bonding material, it is possible to control the aforementioned maximum reaching distance. That is, when the specific surface area of the Ag powder is small, the sinterability of the paste-like bonding material becomes high, the liquid phase is likely to occur in the pressurization and heating process, the diffusion of the active metal is promoted, and the maximum reach distance described above is increased. becomes longer. On the other hand, when the specific surface area of the Ag powder is large, the sinterability of the paste-like bonding material becomes low, making it difficult to generate a liquid phase in the pressurization and heating processes, suppressing the diffusion of the active metal, and increasing the maximum reach distance described above. becomes shorter.
Alternatively, bonding materials containing different types and amounts of active metals may be used to separately paint the peripheral edge portion and the central portion of the copper plate.
　さらに、本実施形態においては、回路層を、無酸素銅の圧延板をセラミックス基板に接合することにより形成するものとして説明したが、これに限定されることはなく、銅板を打ち抜いた銅片を回路パターン状に配置された状態でセラミックス基板に接合されることによって回路層を形成してもよい。この場合、それぞれの銅片において、上述のようなセラミックス基板との界面構造を有していればよい。
　また、本実施形態では、銅板の接合面に接合材を配設するものとして説明したが、これに限定されることはなく、セラミックス基板と銅板の間に接合材が配設されていればよく、セラミックス基板の接合面に接合材を配設してもよい。 Furthermore, in the present embodiment, the circuit layer was described as being formed by bonding a rolled plate of oxygen-free copper to a ceramic substrate, but the present invention is not limited to this, and a copper piece punched out of a copper plate is used. A circuit layer may be formed by bonding to a ceramic substrate while being arranged in a circuit pattern. In this case, each copper piece should have the interface structure with the ceramic substrate as described above.
Further, in the present embodiment, the bonding material is provided on the bonding surface of the copper plate, but the present invention is not limited to this, and the bonding material may be provided between the ceramic substrate and the copper plate. Alternatively, a bonding material may be provided on the bonding surface of the ceramic substrate.
　以下に、本発明の効果を確認すべく行った確認実験の結果について説明する。 The results of confirmation experiments conducted to confirm the effects of the present invention are described below.
　まず、表１記載のセラミックス基板（４０ｍｍ×４０ｍｍ）を準備した。なお、厚さは、ＡｌＮおよびＡｌ２Ｏ３は０．６３５ｍｍ、Ｓｉ３Ｎ４は０．３２ｍｍとした。
　また、回路層および金属層となる銅板として、無酸素銅からなり、表１に示す厚さの３７ｍｍ×３７ｍｍの銅板を準備した。 First, a ceramic substrate (40 mm×40 mm) shown in Table 1 was prepared. The thickness of AlN and Al 2 O 3 was 0.635 mm, and the thickness of Si 3 N 4 was 0.32 mm.
In addition, a copper plate made of oxygen-free copper and having a thickness of 37 mm×37 mm and having a thickness shown in Table 1 was prepared as a copper plate serving as a circuit layer and a metal layer.
　回路層および金属層となる銅板の周縁部に、表１に示すＢＥＴ値のＡｇ粉を含む接合材を、乾燥後の目標厚さが表１に示す値となるよう塗布した。
　また、回路層および金属層となる銅板の中央部に、表１に示すＢＥＴ値のＡｇ粉を含む接合材を、乾燥後の目標厚さが表１に示す値となるよう塗布した。
　なお、接合材はペースト材を用い、Ａｇ，Ｃｕ，活性金属の量は表１の通りとした。
　また、Ａｇ粉のＢＥＴ値（比表面積）はＱＵＡＮＴＡＣＨＲＲＯＭＥ社製ＡＵＴＯＳＯＲＢ－１を用い、前処理として１５０℃で３０分加熱の真空脱気を行い、Ｎ２吸着、液体窒素７７Ｋ、ＢＥＴ多点法で測定した。 A bonding material containing Ag powder having a BET value shown in Table 1 was applied to the peripheral portion of the copper plate serving as the circuit layer and the metal layer so that the target thickness after drying would be the value shown in Table 1.
In addition, a bonding material containing Ag powder having a BET value shown in Table 1 was applied to the central portion of the copper plate serving as the circuit layer and the metal layer so that the target thickness after drying would be the value shown in Table 1.
A paste material was used as the bonding material, and the amounts of Ag, Cu, and active metal were as shown in Table 1.
In addition, the BET value (specific surface area) of the Ag powder was measured by using AUTOSORB-1 manufactured by QUANTACHRROME, vacuum deaeration by heating at 150 ° C. for 30 minutes as pretreatment, N 2 adsorption, liquid nitrogen 77 K, BET multipoint method. It was measured.
　セラミックス基板の一方の面に、回路層となる銅板を積層した。また、セラミックス基板の他方の面に、金属層となる銅板を積層した。 A copper plate, which will be the circuit layer, is laminated on one side of the ceramic substrate. A copper plate serving as a metal layer was laminated on the other surface of the ceramic substrate.
　この積層体を、積層方向に加圧した状態で加熱し、Ａｇ－Ｃｕ液相を発生させた。このとき、加圧荷重を０．２９４ＭＰａとし，温度積分値は表２の通りとした。
　そして、加熱した積層体を冷却することにより、回路層となる銅板とセラミックス基板と金属層となる金属板を接合し、絶縁回路基板（銅／セラミックス接合体）を得た。 This laminate was heated while being pressed in the lamination direction to generate an Ag—Cu liquid phase. At this time, the pressure load was set to 0.294 MPa, and the temperature integral value was set as shown in Table 2.
Then, by cooling the heated laminate, the copper plate serving as the circuit layer, the ceramic substrate, and the metal plate serving as the metal layer were bonded to obtain an insulated circuit substrate (copper/ceramic bonded body).
　得られた絶縁回路基板（銅／セラミックス接合体）について、活性金属拡散領域、活性金属化合物層、Ａｇ－Ｃｕ合金層、冷熱サイクル信頼性を、以下のようにして評価した。 For the obtained insulated circuit board (copper/ceramic bonded body), the active metal diffusion region, active metal compound layer, Ag-Cu alloy layer, and thermal cycle reliability were evaluated as follows.
（活性金属拡散領域の最大到達距離）
　回路層とセラミックス基板との接合界面、および、セラミックス基板と金属層との接合界面の断面を、ＥＰＭＡ装置によって観察し、回路層および金属層中の活性金属に関して元素マップ（幅２００μｍ×高さ２００μｍ）を、それぞれ５視野ずつ取得した。
　そして、活性金属の濃度が０．５質量％以上である活性金属拡散領域の活性金属化合物層からの最大到達距離を測定した。なお、活性金属の濃度は、Ａｇ、Ｃｕ、活性金属の各濃度の合算を１００質量％とした値である。各５視野、計１０視野での最大到達距離のうち、最も大きい最大到達距離を表２に記載した。 (maximum reaching distance of active metal diffusion region)
The cross section of the bonding interface between the circuit layer and the ceramic substrate and the bonding interface between the ceramic substrate and the metal layer were observed with an EPMA device, and an elemental map (width 200 μm × height 200 μm) was obtained for active metals in the circuit layer and the metal layer. ) were acquired in 5 fields each.
Then, the maximum reaching distance from the active metal compound layer of the active metal diffusion region having an active metal concentration of 0.5% by mass or more was measured. In addition, the concentration of the active metal is a value in which the sum of the respective concentrations of Ag, Cu, and active metal is 100% by mass. Table 2 lists the maximum reachable distance among the maximum reachable distances in each of the 5 fields of view and a total of 10 fields of view.
（活性金属化合物層）
　回路層とセラミックス基板との接合界面、および、セラミックス基板と金属層との接合界面の断面を、走査型電子顕微鏡（カールツァイスＮＴＳ社製ＵＬＴＲＡ５５、加速電圧１．８ｋＶ）を用いて倍率３００００倍で測定し、エネルギー分散型Ｘ線分析法により、Ｎ、Ｏ及び活性金属元素の元素マッピングをそれぞれ５視野取得した。活性金属元素とＮまたはＯが同一領域に存在する場合に活性金属化合物層が有ると判断した。
　それぞれ５視野、計１０視野で観察を行い、活性金属元素とＮまたはＯが同一領域に存在する範囲の面積を、測定した幅で割ったものの平均値を「活性金属化合物層の厚さ」として表２に記載した。 (Active metal compound layer)
A cross-section of the bonding interface between the circuit layer and the ceramic substrate and the bonding interface between the ceramic substrate and the metal layer was examined using a scanning electron microscope (ULTRA55 manufactured by Carl Zeiss NTS, acceleration voltage 1.8 kV) at a magnification of 30,000. Measured, and elemental mapping of N, O and active metal elements was obtained for each of 5 fields by the energy dispersive X-ray analysis method. It was determined that there was an active metal compound layer when the active metal element and N or O were present in the same region.
Observations were made in 5 fields of view, for a total of 10 fields of view, and the average value obtained by dividing the area of the range where the active metal element and N or O existed in the same region by the measured width was taken as the "thickness of the active metal compound layer." It described in Table 2.
（Ａｇ－Ｃｕ合金層）
　回路層とセラミックス基板との接合界面、および、セラミックス基板と金属層との接合界面の断面を、ＥＰＭＡ装置を用いて、Ａｇ，Ｃｕ，活性金属の各元素マッピングを取得した。それぞれ５視野で各元素マッピングを取得した。
　そして、Ａｇ＋Ｃｕ＋活性金属＝１００質量％としたとき、Ａｇ濃度が１５質量％以上である領域をＡｇ－Ｃｕ合金層とし、その面積を求めて、測定領域の幅で割った値（面積／測定領域の幅）を求めた。その値の平均をＡｇ－Ｃｕ合金層の厚さとして表２に記載した。 (Ag—Cu alloy layer)
Elemental mapping of Ag, Cu, and active metals was obtained for cross sections of the bonding interface between the circuit layer and the ceramic substrate and the bonding interface between the ceramic substrate and the metal layer using an EPMA apparatus. Each elemental mapping was acquired in each of 5 fields of view.
Then, when Ag + Cu + active metal = 100% by mass, the area where the Ag concentration is 15% by mass or more is defined as the Ag-Cu alloy layer, and the area is obtained and divided by the width of the measurement area (area / measurement area width). The average of the values is shown in Table 2 as the thickness of the Ag--Cu alloy layer.
（冷熱サイクル信頼性）
　上述の絶縁回路基板を、セラミックス基板の材質に応じて、下記の冷熱サイクルを負荷し、ＳＡＴ検査（超音波探傷検査）によりセラミックス割れの有無を判定した。評価結果を表２に示す。
　ＡｌＮ，Ａｌ２Ｏ３の場合：－４０℃×５ｍｉｎ←→１５０℃×５ｍｉｎを５００サイクルまで５０サイクル毎にＳＡＴ検査。
　Ｓｉ３Ｎ４の場合：－４０℃×５ｍｉｎ←→１５０℃×５ｍｉｎを２０００サイクルまで２００サイクル毎にＳＡＴ検査。 (Cold/heat cycle reliability)
Depending on the material of the ceramic substrate, the insulating circuit substrate described above was subjected to the following cooling and heating cycles, and the presence or absence of cracks in the ceramics was determined by SAT inspection (ultrasonic inspection). Table 2 shows the evaluation results.
For AlN, Al 2 O 3 : −40° C.×5 min←→150° C.×5 min, SAT inspection every 50 cycles up to 500 cycles.
For Si 3 N 4 : SAT inspection every 200 cycles up to 2000 cycles at −40° C.×5 min←→150° C.×5 min.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　まず、セラミックス基板としてＡｌＮを用いた本発明例１～３と比較例１，２とを比較する。
　比較例１においては、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡと、銅板の中央部領域における活性金属拡散領域の前記最大到達距離ＬＢとの差が１５μｍとされるとともに、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡが１２μｍとされており、冷熱サイクル試験において割れ発生回数が２００回となった。
　比較例２においては、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡが１６μｍ、銅板の中央部領域における活性金属拡散領域の前記最大到達距離ＬＢが１９μｍとされており、冷熱サイクル試験において割れ発生回数が１５０回となった。 First, invention examples 1 to 3 using AlN as a ceramic substrate and comparative examples 1 and 2 are compared.
In Comparative Example 1, the difference between the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was set to 15 μm. , the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate is set to 12 μm, and the number of cracks generated is 200 times in the thermal cycle test.
In Comparative Example 2, the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate is 16 μm, and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate is 19 μm. In the cycle test, cracks occurred 150 times.
　これに対して、本発明例１～３においては、銅板の周縁部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＡおよび銅板の中央部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、前記最大到達距離ＬＡと前記最大到達距離ＬＢとの差が１０μｍ以下とされており、冷熱サイクル試験において割れ発生回数が３００～５００回となり、冷熱サイクル信頼性に優れていた。 On the other hand, in Examples 1 to 3 of the present invention, the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate The maximum reaching distance LB from the compound layer is set to be in the range of 20 μm or more and 80 μm or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 μm or less. The number of times cracks occurred was 300 to 500, indicating excellent thermal cycle reliability.
　次に、セラミックス基板としてＳｉ３Ｎ４を用いた本発明例４～６と比較例３，４とを比較する。
　比較例３においては、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡが１０８μｍ、銅板の中央部領域における活性金属拡散領域の前記最大到達距離ＬＢが１０２μｍとされており、冷熱サイクル試験において割れ発生回数が１２００回となった。
　比較例４においては、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡと、銅板の中央部領域における活性金属拡散領域の前記最大到達距離ＬＢとの差が１４μｍとされており、冷熱サイクル試験において割れ発生回数が１４００回となった。 Next, inventive examples 4 to 6 using Si 3 N 4 as the ceramic substrate and comparative examples 3 and 4 are compared.
In Comparative Example 3, the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate was 108 μm, and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 102 μm. In the cycle test, cracks occurred 1200 times.
In Comparative Example 4, the difference between the maximum reaching distance LA of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 14 μm. , the number of cracks occurred 1400 times in the thermal cycle test.
　これに対して、本発明例４～６においては、銅板の周縁部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＡおよび銅板の中央部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、前記最大到達距離ＬＡと前記最大到達距離ＬＢとの差が１０μｍ以下とされており、冷熱サイクル試験において割れ発生回数が１６００～２０００回超えとなり、冷熱サイクル信頼性に優れていた。 On the other hand, in Examples 4 to 6 of the present invention, the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate The maximum reaching distance LB from the compound layer is set to be in the range of 20 μm or more and 80 μm or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 μm or less. The number of times cracks occurred exceeded 1,600 to 2,000 times, indicating excellent thermal cycle reliability.
　次に、セラミックス基板としてＡｌ２Ｏ３を用いた本発明例７，８と比較例５とを比較する。
　比較例５においては、銅板の周縁部領域における活性金属拡散領域の最大到達距離ＬＡが１６μｍ、銅板の中央部領域における活性金属拡散領域の最大到達距離ＬＢが１８μｍとされており、冷熱サイクル試験において割れ発生回数が５０回となった。 Next, inventive examples 7 and 8 using Al 2 O 3 as the ceramic substrate and comparative example 5 are compared.
In Comparative Example 5, the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate was 16 μm, and the maximum reaching distance LB of the active metal diffusion region in the central region of the copper plate was 18 μm. In the test, cracks occurred 50 times.
　これに対して、本発明例７，８においては、銅板の周縁部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＡおよび銅板の中央部領域における活性金属拡散領域の活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、前記最大到達距離ＬＡと前記最大到達距離ＬＢとの差が１０μｍ以下とされており、冷熱サイクル試験において割れ発生回数が３５０～４５０回となり、冷熱サイクル信頼性に優れていた。 On the other hand, in Examples 7 and 8 of the present invention, the maximum reaching distance L A from the active metal compound layer of the active metal diffusion region in the peripheral region of the copper plate and the active metal diffusion region in the central region of the copper plate The maximum reaching distance LB from the compound layer is set to be in the range of 20 μm or more and 80 μm or less, and the difference between the maximum reaching distance LA and the maximum reaching distance LB is set to 10 μm or less. The number of times cracks occurred was 350 to 450, indicating excellent thermal cycle reliability.
　以上の確認実験の結果から、本発明例によれば、厳しい冷熱サイクルを負荷した場合であっても、セラミックス部材における割れの発生を抑制でき、冷熱サイクル信頼性に優れた絶縁回路基板（銅／セラミックス接合体）を提供可能であることが確認された。 From the results of the above confirmation experiments, according to the example of the present invention, even when a severe thermal cycle is applied, the occurrence of cracks in the ceramic member can be suppressed, and the insulated circuit board (copper / It was confirmed that it is possible to provide a ceramic bonded body).
　本実施形態の銅／セラミックス接合体及び絶縁回路基板は、パワーモジュール、ＬＥＤモジュールおよび熱電モジュールに好適に適用される。 The copper/ceramic bonded body and insulating circuit board of this embodiment are suitably applied to power modules, LED modules and thermoelectric modules.
１０　絶縁回路基板（銅／セラミックス接合体）
１１　セラミックス基板（セラミックス部材）
１２　回路層（銅部材）
１３　金属層（銅部材）
２１（２１Ａ，２１Ｂ）　活性金属化合物層
２２（２２Ａ，２２Ｂ）　Ａｇ－Ｃｕ合金層
２３（２３Ａ，２３Ｂ）　活性金属拡散領域 10 Insulated circuit board (copper/ceramic joint)
11 Ceramic substrate (ceramic member)
12 circuit layer (copper member)
13 metal layer (copper member)
21 (21A, 21B) active metal compound layer 22 (22A, 22B) Ag—Cu alloy layer 23 (23A, 23B) active metal diffusion region

Claims (6)

  1. 　銅又は銅合金からなる銅部材と、セラミックス部材とが接合されてなる銅／セラミックス接合体であって、
    　前記セラミックス部材と前記銅部材との接合界面において、前記セラミックス部材側には活性金属化合物層が形成されており、
    　前記銅部材のうち前記セラミックス部材側には、活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆ）が前記セラミックス部材側から前記銅部材側へと拡散することにより、前記銅部材中の前記活性金属の濃度が０．５質量％以上である活性金属拡散領域が形成されており、
    　前記銅部材の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＡおよび前記銅部材の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、
    　前記銅部材の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅部材の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下であることを特徴とする銅／セラミックス接合体。     A copper/ceramic joined body obtained by joining a copper member made of copper or a copper alloy and a ceramic member,
    An active metal compound layer is formed on the ceramic member side at the bonding interface between the ceramic member and the copper member,
    Active metals (Ti, Zr, Nb, Hf) are diffused from the ceramic member side to the copper member side of the copper member on the ceramic member side, thereby increasing the concentration of the active metal in the copper member. is 0.5% by mass or more, and an active metal diffusion region is formed,
    A maximum reaching distance LA of the active metal diffusion region from the active metal compound layer in the peripheral region of the copper member and a maximum reaching distance of the active metal diffusion region from the active metal compound layer in the central region of the copper member The distance LB is within the range of 20 μm or more and 80 μm or less,
    A difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper member and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper member is 10 μm or less. A copper/ceramic bonded body characterized by:
  2. 　前記銅部材の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅部材の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされ、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされていることを特徴とする請求項１に記載の銅／セラミックス接合体。 The thickness t1A of the active metal compound layer formed in the peripheral region of the copper member and the thickness t1B of the active metal compound layer formed in the central region of the copper member are 0.05 μm or more1 . 2. The copper/ceramic joined body according to claim 1, wherein the thickness is within the range of 2 μm or less, and the thickness ratio t1A / t1B is within the range of 0.7 or more and 1.4 or less.
  3. 　前記セラミックス部材と前記銅部材との接合界面において、前記銅部材側にはＡｇ－Ｃｕ合金層が形成されており、
    　前記銅部材の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅部材の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされ、厚さ比ｔ２Ａ／ｔ２Ｂが０．７以上１．４以下の範囲内とされていることを特徴とする請求項１または請求項２に記載の銅／セラミックス接合体。     At the bonding interface between the ceramic member and the copper member, an Ag—Cu alloy layer is formed on the copper member side,
    The thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper member and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper member are 1 μm or more and 30 μm or less. , and the thickness ratio t2 A / t2 B is within the range of 0.7 or more and 1.4 or less. Copper / ceramics joined body according to claim 1 or 2 .
  4. 　セラミックス基板の表面に、銅又は銅合金からなる銅板が接合されてなる絶縁回路基板であって、
    　前記セラミックス基板と前記銅板との接合界面において、前記セラミックス基板側には活性金属化合物層が形成されており、
    　前記銅板のうち前記セラミックス基板側には、活性金属（Ｔｉ，Ｚｒ，Ｎｂ，Ｈｆ）が前記セラミックス基板側から前記銅板側へと拡散することにより、前記銅板中の前記活性金属の濃度が０．５質量％以上である活性金属拡散領域が形成されており、
    　前記銅板の周縁部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＡおよび前記銅板の中央部領域における前記活性金属拡散領域の前記活性金属化合物層からの最大到達距離ＬＢが２０μｍ以上８０μｍ以下の範囲内とされるとともに、
    　前記銅板の周縁部領域における前記活性金属拡散領域の前記最大到達距離ＬＡと、前記銅板の中央部領域における前記活性金属拡散領域の前記最大到達距離ＬＢとの差が１０μｍ以下であることを特徴とする絶縁回路基板。     An insulated circuit board formed by bonding a copper plate made of copper or a copper alloy to the surface of a ceramic substrate,
    At the bonding interface between the ceramic substrate and the copper plate, an active metal compound layer is formed on the ceramic substrate side,
    Active metals (Ti, Zr, Nb, Hf) are diffused from the ceramic substrate side to the copper plate side of the copper plate on the ceramic substrate side, so that the concentration of the active metals in the copper plate is reduced to 0.0. an active metal diffusion region of 5% by mass or more is formed;
    Maximum reaching distance L A of the active metal diffusion region from the active metal compound layer in the peripheral region of the copper plate and maximum reaching distance L of the active metal diffusion region from the active metal compound layer in the central region of the copper plate B is in the range of 20 μm or more and 80 μm or less,
    The difference between the maximum reaching distance L A of the active metal diffusion region in the peripheral region of the copper plate and the maximum reaching distance L B of the active metal diffusion region in the central region of the copper plate is 10 μm or less. An insulated circuit board, characterized in that:
  5. 　前記銅板の周縁部領域に形成された前記活性金属化合物層の厚さｔ１Ａおよび前記銅板の中央部領域に形成された前記活性金属化合物層の厚さｔ１Ｂが０．０５μｍ以上１．２μｍ以下の範囲内とされ、厚さ比ｔ１Ａ／ｔ１Ｂが０．７以上１．４以下の範囲内とされていることを特徴とする請求項４に記載の絶縁回路基板。 The thickness t1A of the active metal compound layer formed in the peripheral region of the copper plate and the thickness t1B of the active metal compound layer formed in the central region of the copper plate are 0.05 μm or more and 1.2 μm or less. and the thickness ratio t1A / t1B is in the range of 0.7 to 1.4.
  6. 　前記セラミックス基板と前記銅板との接合界面において、前記銅板側にはＡｇ－Ｃｕ合金層が形成されており、
    　前記銅板の周縁部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ａおよび前記銅板の中央部領域に形成された前記Ａｇ－Ｃｕ合金層の厚さｔ２Ｂが１μｍ以上３０μｍ以下の範囲内とされ、厚さ比ｔ２Ａ／ｔ２Ｂが０．７以上１．４以下の範囲内とされていることを特徴とする請求項４または請求項５に記載の絶縁回路基板。     At the bonding interface between the ceramic substrate and the copper plate, an Ag—Cu alloy layer is formed on the copper plate side,
    The thickness t2A of the Ag--Cu alloy layer formed in the peripheral region of the copper plate and the thickness t2B of the Ag--Cu alloy layer formed in the central region of the copper plate are in the range of 1 μm or more and 30 μm or less. 6. The insulated circuit board according to claim 4, wherein the thickness ratio t2A / t2B is in the range of 0.7 to 1.4.
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