US-12622268-B2 - Copper/ceramic bonded body and insulating circuit substrate

US12622268B2US 12622268 B2US12622268 B2US 12622268B2US-12622268-B2

Abstract

The copper/ceramic bonded body according to the present invention is a copper/ceramic bonded body obtained by bonding copper members consisting of copper or a copper alloy to a ceramic member, where at a bonded interface between the ceramic member and each of the copper members, the distance between the ceramic member and each of the copper members in an end portion of each of the copper members is in a range of 3 μm or more and 30 μm or less, and a void ratio in an end portion region (E) of each of the copper members is 10% or less.

Inventors

Nobuyuki Terasaki

Assignees

MITSUBISHI MATERIALS CORPORATION

Dates

Publication Date: 20260505
Application Date: 20220729
Priority Date: 20210730

Claims (17)

1 . A copper/ceramic bonded body obtained by bonding a copper member consisting of copper or a copper alloy to a ceramic member, wherein the copper member has a chamfered surface on a peripheral edge of a surface that faces the ceramic member to form a crevice between the copper member and the ceramic member, a height h of the crevice from a surface of the ceramic member to an outermost edge of the copper member in a lamination direction is in a range of 3 μm or more and 30 μm or less, and a void ratio in an end portion region of the copper member is 10% or less, the end portion region being a rectangular area enclosed by 30 μm in height and 400 μm in width at a bottom peripheral part of the copper member in a cross section in the lamination direction, a vertical side of the rectangular area closer to the peripheral edge is collinear with a virtual vertical line drawn from an intersection P to the surface of the ceramic member, the intersection P being an intersection of a side of the copper member and a line parallel to the surface of the ceramic member at a location ⅓ of a thickness of the copper member from the surface of the ceramic member.
2 . The copper/ceramic bonded body according to claim 1 , wherein at the bonded interface between the ceramic member and the copper member, an active metal compound layer is formed on a side of the ceramic member, and a thickness t 1 A of the active metal compound layer from an end portion of the copper member, the end portion being a rectangular region extending from an outermost surface of the copper member 200 μm inward in the width direction in a cross section along the lamination direction, and a thickness t 1 B of the active metal compound layer from a central part of the copper member are in a range of 0.05 μm or more and 1.2 μm or less, where a thickness ratio t 1 A /t 1 B is in a range of 0.7 or more and 1.4 or less, the central part being a rectangular region of 200 μm in a width direction including a center of the copper member at a center thereof in the cross section.
3 . The copper/ceramic bonded body according to claim 1 , wherein at the bonded interface between the ceramic member and the copper member, an Ag—Cu alloy layer is formed on a side of the copper member, and a thickness t 2 A of the Ag—Cu alloy layer from an end portion of the copper member, the end portion being a rectangular region extending from an outermost surface of the copper member 200 μm inward in the width direction in a cross section along the lamination direction, and a thickness t 2 B of the Ag—Cu alloy layer from a central part of the copper member are in a range of 3 μm or more and 30 μm or less, where a thickness ratio t 2 A /t 2 B is in a range of 0.7 or more and 1.4 or less, the central part being a rectangular region of 200 μm in a width direction including a center of the copper member at a center thereof in the cross section.
4 . An insulating circuit substrate obtained by bonding a copper sheet consisting of copper or a copper alloy to a surface of a ceramic substrate, wherein the copper sheet has a chamfered surface on a peripheral edge of a surface that faces the ceramic substrate to form a crevice between the copper sheet and the ceramic substrate, at a bonded interface between the ceramic substrate and the copper sheet, a height h of the crevice from a surface of the ceramic substrate to an outermost edge of the copper sheet in a lamination direction is set to be in a range of 3 μm or more and 30 μm or less, and a void ratio in an end portion region of the copper sheet is 10% or less, the end portion region being a rectangular area enclosed by 30 μm in height and 400 μm in width at a bottom peripheral part of the copper sheet in a cross section in the lamination direction, a vertical side of the rectangular area closer to the peripheral edge is collinear with a virtual vertical line drawn from an intersection P to the surface of the ceramic substrate, the intersection P being an intersection of a side of the copper sheet and a line parallel to the surface of the ceramic substrate at a location ⅓ of a thickness of the copper sheet from the surface of the ceramic substrate.
5 . The insulating circuit substrate according to claim 4 , wherein at the bonded interface between the ceramic substrate and the copper sheet, an active metal compound layer is formed on a side of the ceramic substrate, and a thickness t 1 A of the active metal compound layer from an end portion of the copper sheet, the end portion being a rectangular region extending from an outermost surface of the copper sheet 200 μm inward in the width direction in a cross section along the lamination direction, and a thickness t 1 B of the active metal compound layer from a central part of the copper sheet are in a range of 0.05 μm or more and 1.2 μm or less, where a thickness ratio t 1 A /t 1 B is in a range of 0.7 or more and 1.4 or less, the central part being a rectangular region of 200 μm in a width direction including a center of the copper sheet at a center thereof in the cross section.
6 . The insulating circuit substrate according to claim 4 , wherein at the bonded interface between the ceramic substrate and the copper sheet, an Ag—Cu alloy layer is formed on a side of the copper sheet, and a thickness t 2 A of the Ag—Cu alloy layer from an end portion of the copper sheet, the end portion being a rectangular region extending from an outermost surface of the copper sheet 200 μm inward in the width direction in a cross section along the lamination direction, and a thickness t 2 B of the Ag—Cu alloy layer from a central part of the copper sheet are in a range of 3 μm or more and 30 μm or less, where a thickness ratio t 2 A /t 2 B is in a range of 0.7 or more and 1.4 or less, the central part being a rectangular region of 200 μm in a width direction including a center of the copper sheet at a center thereof in the cross section.
7 . The copper/ceramic bonded body according to claim 1 , wherein the ceramic member is made of one of silicon nitride, aluminum nitride, and alumina.
8 . The copper/ceramic bonded body according to claim 1 , wherein the copper member is made of a rolled plate of oxygen-free copper.
9 . The copper/ceramic bonded body according to claim 1 , wherein a thickness of the ceramic member is 0.2 mm or more and 1.5 mm or less.
10 . The copper/ceramic bonded body according to claim 1 , wherein the thickness of the copper member is 0.1 mm or more and 2.0 mm or less.
11 . The copper/ceramic bonded body according to claim 2 , wherein the ceramic substrate is made of silicon nitride or aluminum nitride, and the active metal compound layer is formed of aggregated particles of a nitride of Ti, Zr, Nb or Hf, and an average particle size thereof is 10 nm or more and 100 nm or less.
12 . The copper/ceramic bonded body according to claim 2 , wherein the ceramic substrate is made of aluminum oxide, and the active metal compound layer is formed of aggregated particles of an oxide of Ti, Zr, Nb or Hf, and an average particle size thereof is 10 nm or more and 100 nm or less.
13 . The insulating circuit substrate according to claim 4 , wherein the copper sheet is made of a rolled plate of oxygen-free copper.
14 . The insulating circuit substrate according to claim 4 , wherein a thickness of the ceramic substrate is 0.2 mm or more and 1.5 mm or less.
15 . The insulating circuit substrate according to claim 4 , wherein the thickness of the copper sheet is 0.1 mm or more and 2.0 mm or less.
16 . The insulating circuit substrate according to claim 5 , wherein the ceramic substrate is made of silicon nitride or aluminum nitride, and the active metal compound layer is formed of aggregated particles of a nitride of Ti, Zr, Nb or Hf, and an average particle size thereof is 10 nm or more and 100 nm or less.
17 . The insulating circuit substrate according to claim 5 , wherein the active metal compound layer is formed of aggregated particles of an oxide of Ti, Zr, Nb or Hf, and an average particle size thereof is 10 nm or more and 100 nm or less.

Description

TECHNICAL FIELD The present invention relates to a copper/ceramic bonded body obtained by bonding a copper member consisting of copper or a copper alloy to a ceramic member, and an insulating circuit substrate including a ceramic substrate and a copper sheet consisting of copper or a copper alloy, which is bonded to a surface of the ceramic substrate. Priority is claimed on Japanese Patent Application No. 2021-125531, filed Jul. 30, 2021, the content of which is incorporated herein by reference. BACKGROUND ART 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 bonded to an insulating circuit substrate in which a circuit layer consisting of a conductive material is formed on one surface of an insulating layer. For example, a power semiconductor element for high power control, which is used for controlling wind power generation, an electric vehicle, a hybrid vehicle, or the like, generates a large amount of heat during operation, and thus, an insulating circuit substrate including a ceramic substrate, a circuit layer formed by bonding a metal plate having excellent electrical conductivity to one surface of the ceramic substrate, and a metal layer for heat radiation, which is formed by bonding a metal plate to the other surface of the ceramic substrate has been widely used in the related art as a substrate on which the power semiconductor element is mounted. For example, Patent Document 1 proposes an insulating circuit substrate in which a circuit layer and a metal layer are formed by bonding a copper sheet to one surface and the other surface of a ceramic substrate. In Patent Document 1, the copper sheet is disposed on one surface of the ceramic substrate and the other surface thereof with an Ag—Cu—Ti-based brazing material being interposed, and then a heating treatment is carried out to bond the copper sheet (so-called active metal brazing method). In addition, Patent Document 2 proposes a power module substrate in which a copper sheet consisting of copper or a copper alloy is bonded to a ceramic substrate consisting of AlN or Al2O3 by using a bonding material containing Ag and Ti. Further, Patent Document 3 proposes a power module substrate in which an aluminum sheet consisting of aluminum or an aluminum alloy is bonded to a ceramic substrate by using a brazing material consisting of an alloy such as an Al—Si-based, Al—Ge-based, Al—Cu-based, Al—Mg-based, or Al—Mn-based alloy. In addition, according to Patent Document 3, an overhang part is formed in the periphery of each of a circuit layer formed on one surface of the ceramic substrate and a heat radiation layer formed on the other surface of the ceramic substrate. As a result, insulating properties between the circuit layer and the heat radiation layer are ensured, and concurrently, the heat capacity in the circuit layer and the heat radiation layer is increased. CITATION LIST Patent Documents [Patent Document 1] Japanese Patent No. 3211856 [Patent Document 2] Japanese Patent No. 5757359 [Patent Document 3] Japanese Patent No. 5957862 SUMMARY OF INVENTION Technical Problem By the way, in recent years, there is a tendency that a heat generation temperature of a semiconductor element mounted on an insulating circuit substrate increases, and an insulating circuit substrate is required to have a thermal cycle reliability that can withstand a thermal cycle more severe than a thermal cycle in the related art. Here, in an insulating circuit substrate obtained by bonding a copper sheet to a ceramic substrate, in a case where an overhang part is formed on the circuit layer as described in Patent Document 3, there is a risk that thermal stress is concentrated on the end portion of the circuit layer, and the bonding reliability is decreased in a case where a thermal cycle is loaded. On the other hand, in a case where the thickness of the bonding layer in the end portion is increased in order to ensure the strength in the end portion of the copper member, there is a risk that a bonding material arranged between the copper member and the ceramic member protrudes out to cause a defect called “braze staining” occurs. The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a copper/ceramic bonded body in which thermal cycle reliability is excellent and the occurrence of braze staining is sufficiently suppressed, and an insulating circuit substrate consisting of this copper/ceramic bonded body. Solution to Problem In order to solve the above-described problem, the copper/ceramic bonded body according to one aspect of the present invention is characterized being a copper/ceramic bonded body obtained by bonding a copper member consisting of copper or a copper alloy to a ceramic member, in which at a bonded interface between the ceramic member and the copper member, the dista