Copper-based plate material, and heat dissipation substrate, bus bar, rectangular wire, and round wire each using same

Abstract

Provided is a copper-based plate material which is capable of improving bondability with ceramics by suppressing coarsening of crystal grains when heating is performed in a temperature range of about 300°C to about 1000°C, and is also capable of suppressing the generation of thermal stress by suppressing increase in Young's modulus.　The copper-based plate material contains, in addition to 99.99 mass% or more of copper (Cu), a total of 11 mass ppm to 40 mass ppm inclusive of one or more elements selected from among manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), and in both the surface after heating at 300°C for 1 hour and the surface after heating at 1000°C for 1 hour, the ratio of the area of crystal grains oriented within 20° from the Cube orientation is higher than the ratio of the area of crystal grains oriented within 20° from the R orientation.

Description

Copper-based sheet material, and heat dissipation substrates, busbars, flat wires, and round wires using the same.

[0001] The present invention relates to copper-based sheet materials, and to heat dissipation substrates, busbars, rectangular wires, and round wires using the same.

[0002] In general, power devices generate a significant amount of heat from semiconductor elements due to the use of high voltage and high current, and the degradation of materials caused by this heat is a major concern. Since this can lead to damage to electrical and electronic equipment components, measures are being taken to counteract material degradation due to heat by using heat dissipation substrates, which consist of ceramic substrates with excellent insulation and heat dissipation properties bonded to copper plates.

[0003] Here, methods such as joining ceramic substrates and copper plates via a brazing material such as silver, or direct joining using the eutectic reaction of copper without a brazing material, are used. However, joining via a brazing material requires heating to over 800°C, and direct joining without a brazing material requires heating to over 1000°C. In this case, aluminum nitride, alumina, silicon nitride, etc. are used as ceramic substrates, but because these ceramic substrates have a large difference in thermal expansion coefficients compared to copper plates, heating during the joining of the ceramic substrate and copper plate tends to cause large strains throughout the resulting heat dissipation substrate. More specifically, when a ceramic substrate and a copper plate are joined, the copper plate has a higher thermal expansion coefficient than the ceramic substrate, so heating easily applies compressive stress to the copper plate and tensile stress to the ceramic substrate. Furthermore, the large strains that occur in the heat dissipation substrate obtained by joining make delamination of the joint between the copper plate and the ceramic substrate more likely. Therefore, there is a need for a copper plate that generates minimal thermal stress when heated to the temperature required for bonding with a ceramic substrate.

[0004] In this regard, Patent Document 1 describes a pure copper material having a Cu content of 99.96% by mass or more, containing one or more A group elements selected from Ca, Ba, Sr, Zr, Hf, Y, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and one or both of the B group elements selected from O, S, Se, Te in a total amount of 10 ppm by mass or more and 300 ppm by mass or less, having an average grain size of 15 μm or more on the rolled surface, and a high-temperature Vickers hardness of 4.0 HV or more and 10.0 HV or less at 850°C. According to the pure copper material of Patent Document 1, it is possible to provide a pure copper material in which the change in crystal structure is small even after heat treatment, and variations in grain size are suppressed, resulting in a uniform crystal structure.

[0005] Furthermore, Patent Document 2 describes a copper plate material for insulating substrates with a copper plate, characterized in that it has a composition in which the total content of metal components selected from the group consisting of Al, Be, Cd, Mg, Pb, Ni, P, Sn, and Cr is 0.1 to 2.0 ppm, and the copper content is 99.96 mass% or more, and when the crystal orientation distribution function obtained from texture analysis by EBSD is expressed in terms of Euler angles (φ1, Φ, φ2), the average value of the orientation density in the range of φ2 = 0°, φ1 = 0°, and Φ = 0° to 90° is 3.0 or more and less than 35.0, and the maximum value of the orientation density in the range of φ2 = 35°, φ1 = 45° to 55°, and Φ = 65° to 80° is 1.0 or more and less than 30.0, and has a rolled texture. According to the copper plate material for insulating substrates with a copper plate described in Patent Document 2, when bonding the copper plate material to a ceramic substrate, it is possible to reduce the overall load stress on the substrate caused by the difference in thermal expansion coefficients between the copper plate material and the ceramic substrate, and to suppress the heterogeneity of the structure and the decrease in bonding properties due to the growth of crystal grains.

[0006] Japanese Patent Publication No. 2024-019081, International Publication No. 2018 / 181593

[0007] High-purity copper used in copper plates bonded to ceramic substrates has problems in that large thermal stresses are generated during thermal expansion when heated to high temperatures above 800°C (the bonding temperature), and during thermal contraction when cooled from the bonding temperature, reducing the bonding strength with the ceramic substrate. Furthermore, strain occurs at areas where crystal grains have grown, becoming the starting point for grain boundary fracture. In particular, since the reaction between the copper plate and ceramics preferentially proceeds mainly from the grain boundaries of the copper plate's crystal grains, it is thought that if the crystal grains of the copper plate become coarse, the bonding strength between the copper plate and ceramics decreases. On the other hand, if the coarsening of the copper plate's crystal grains is suppressed and a fine structure is formed, the higher the density of the crystal grain boundaries in contact with the ceramic interface, the higher the bonding strength between the copper plate and ceramics. In this regard, it is expected that reducing the Young's modulus (longitudinal elastic modulus) of the copper plate and suppressing crystal grain growth at high temperatures above 800°C will reduce the stress load during thermal expansion, thereby preventing grain boundary fracture and improving bonding strength with ceramic substrates.

[0008] In particular, in recent years, with the increasing heat generation of power modules, there has been a trend towards thicker copper plates constituting the heat dissipation substrates. When such copper plates are joined to ceramic substrates, the thermal stress generated between them increases, making it difficult to achieve a sound bond. Therefore, when heating is performed to join the copper plate and the ceramic substrate, it is required that the coarsening of the crystal grains contained in the copper plate is less likely to occur, and that the increase in Young's modulus due to the change in the crystal orientation of the crystal grains is small. In this regard, Patent Documents 1 and 2 do not focus on the change in the crystal orientation of the crystal grains contained in the copper plate, at least.

[0009] In this regard, while the pure copper material in Patent Document 1 controls the grain size when heated (heat-treated) to 850°C, it does not focus on changes in grain size or crystal orientation when heated at higher temperatures. Therefore, it is conceivable that delamination may occur at the joint when, for example, a copper plate of 1 mm or more is joined to a ceramic substrate. Furthermore, it is conceivable that the pure copper material in Patent Document 1 may not be able to join the copper plate and the ceramic substrate when used in a method of directly joining a copper plate and a ceramic substrate at 1000°C or higher without using a brazing material. In addition, because the pure copper material in Patent Document 1 does not undergo a hot rolling process in its manufacturing process, coarse crystal grains derived from the ingot remain in the crystalline structure, which makes it easy for the added elements to segregate, and therefore it is conceivable that the crystalline structure after heating may become non-uniform.

[0010] Furthermore, while the copper plate material for insulating substrates described in Patent Document 2 controls the Young's modulus before heating, it does not consider the Young's modulus and crystal orientation after heating in the temperature range for bonding with the ceramic substrate. Therefore, there was room for improvement, particularly in reducing the change in crystal orientation after heating to lower the Young's modulus and thereby improve the bonding properties of the copper plate to the ceramic substrate.

[0011] Therefore, the present invention has been made in view of the above problems, and aims to provide a copper-based plate material that is suitable as a heat dissipation copper plate material for power semiconductors, which can suppress grain coarsening and improve bonding with ceramics when heated in a temperature range from a relatively low temperature of around 300°C to a high temperature of around 1000°C, and can suppress the generation of thermal stress by suppressing the increase in Young's modulus, as well as a heat dissipation substrate, busbar, rectangular wire, and round wire using the same.

[0012] The inventors have discovered that in a copper-based plate material containing 99.99% by mass or more of copper (Cu) and one or more additive elements selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) in a total amount of 11 ppm by mass or more and 40 ppm by mass or less, in crystal orientation analysis by the EBSD method described later, the proportion of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation is greater than the proportion of the area of ​​crystal grains oriented within 20° from the {231}<346> R orientation on both the surface of the copper-based plate material after heating at 300°C for 1 hour and the surface of the copper-based plate material after heating at 1000°C for 1 hour. This results in a smaller average crystal grain size in the heated copper-based plate material and a smaller change in the Young's modulus of the copper-based plate material before and after heating, thus completing the present invention.

[0013] (1) A copper-based plate material containing 99.99% by mass or more of copper (Cu), and at least one additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), in a total amount of 11 ppm by mass or more and 40 ppm by mass or less, wherein in a crystal orientation analysis by EBSD performed on the surface of the copper-based plate material after a first heating test in which the copper-based plate material was heated at 300°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation to the area of ​​the measurement region is X １ Let Y be the ratio of the area of ​​crystal grains oriented within 20° from the R direction of {231}<346>. １ In that case, X １ Y １ In a larger-than-usual crystal orientation analysis performed on the surface of the copper-based plate material by the EBSD method after a second heating test in which the copper-based plate material was heated at 1000°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region was given by X. ２ The ratio of the area of ​​crystal grains oriented within 20° of the R orientation is defined as Y. ２ In that case, X ２ Y ２ Larger copper-based sheet material.

[0014] (2) In the crystallographic orientation analysis by the EBSD method performed on the surface of the copper-based sheet before the first heating test and the second heating test, the ratio of the area of crystal grains oriented within 20° from the {100}<001> Cube orientation is X ０ When 、 X ０ is 40% or more with respect to the area of the measurement region, and the copper-based sheet according to (1) above.

[0015] (3) The copper-based sheet according to (2) above, wherein the residual resistivity ratios after the first heating test and the second heating test are both in the range of 75 or more and 220 or less.

[0016] (4) The copper-based sheet according to any one of (1) to (3) above, wherein the copper-based sheet has a silver (Ag) content of 16 mass ppm or less, a sulfur (S) content of 10 mass ppm or less, a nickel (Ni) content of 1.0 mass ppm or less, an arsenic (As) content of 0.5 mass ppm or less, a selenium (Se) content of 0.5 mass ppm or less, and an oxygen (O) content of 10 mass ppm or less.

[0017] (5) A heat dissipation substrate made of the copper-based sheet according to any one of (1) to (4) above.

[0018] (6) A bus bar made of the copper-based sheet according to any one of (1) to (4) above.

[0019] (7) A flat wire made of the copper-based sheet according to any one of (1) to (4) above.

[0020] (8) A round wire made of the copper-based sheet according to any one of (1) to (4) above.

[0021] According to the present invention, when heating is performed in a temperature range from a relatively low temperature of around 300°C to a high temperature of around 1000°C, coarsening of crystal grains can be suppressed to improve the bonding property with ceramics, and an increase in Young's modulus can be suppressed to suppress the generation of thermal stress. A copper-based sheet suitable as a heat dissipation copper sheet for a power semiconductor, a heat dissipation substrate, a bus bar, a flat wire, and a round wire using the same can be provided.

[0022] Next, embodiments of the present invention will be described. The following description illustrates examples of embodiments of the present invention and does not limit the scope of the claims.

[0023] The copper-based plate material according to the present invention is a copper-based plate material that contains 99.99% by mass or more of copper (Cu), and at least one additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), in a total amount of 11 ppm by mass or more and 40 ppm by mass or less, wherein in a crystal orientation analysis by EBSD performed on the surface of the copper-based plate material after a first heating test in which the copper-based plate material is heated at 300°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation to the area of ​​the measurement region is X １ Let Y be the ratio of the area of ​​crystal grains oriented within 20° from the R direction of {231}<346>. １ In that case, X １ Y １ In a larger-than-usual crystal orientation analysis performed on the surface of the copper-based plate material by the EBSD method after a second heating test in which the copper-based plate material was heated at 1000°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region was given by X. ２ The ratio of the area of ​​crystal grains oriented within 20° of the R orientation is defined as Y. ２ In that case, X ２ Y ２ Larger.

[0024] In conventional copper-based sheet materials, the crystal orientation of the crystal grains generally changes significantly when heated to high temperatures. When copper-based sheet materials are heated to temperatures above 800°C, such as when bonding to a ceramic substrate to create a heat dissipation substrate, the crystal orientation is not random, but rather forms a crystalline structure oriented toward a specific crystal orientation relative to the sheet surface direction. More specifically, when copper-based sheet materials are heated to temperatures above 800°C, a crystalline structure is formed in which the crystal grains preferentially oriented toward a crystal orientation within 20° of the {231}<346> R(S) orientation. Since this crystal orientation is a crystal orientation with a high Young's modulus, even if the Young's modulus of the copper-based sheet material is low before heating, heating increases the Young's modulus of the copper-based sheet material, generating large thermal stress at the bonding interface with the ceramic substrate, making delamination between the sheet and the ceramic substrate more likely.

[0025] In this regard, the inventors have determined that the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region of the surface after a second heating test in which a copper-based plate material is heated at 1000°C for 1 hour is X ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２ By configuring the structure to be larger, for example, even with high-temperature heating performed when directly joining a copper plate and a ceramic substrate, the development of the R orientation is suppressed, and the {100}<001> cube orientation, which is a crystal orientation with a small Young's modulus, preferentially grows. As a result, the Young's modulus of the copper-based plate material remains low even after joining to the ceramic substrate. Here, when joining a copper-based plate material to a ceramic substrate, delamination may occur at the bonding interface due to thermal expansion and contraction caused by heating and cooling. However, the Young's modulus becomes small, below 115 GPa, both before and after the second heating test simulating joining to a ceramic substrate, and the change in Young's modulus before and after the second heating test is small. This makes delamination at the bonding interface between the copper-based plate material and the ceramic substrate less likely to occur, thus allowing the copper-based plate material and the ceramic substrate to be joined in a good bonding state.

[0026] Furthermore, the copper-based plate material of the present invention not only resists delamination at the bonding interface when bonded to a ceramic substrate, but also has a lower Young's modulus after bonding. This reduces the thermal stress between the copper-based plate material and the ceramic substrate during thermal cycling between room temperature and around 300°C when operating a power module using the copper-based plate material, thus reducing delamination at the bonding interface with the ceramic substrate. As a result, the lifespan of each component equipped with a heat dissipation substrate can be extended, contributing to the long-term stable operation of the power module. In particular, in recent years, due to the increase in heat dissipation in power modules, the copper-based plate material used in power modules has become thicker. Therefore, controlling the thermal stress during thermal cycling between room temperature and around 300°C is becoming an increasingly important technology from the perspective of reducing cracking at the bonding interface with the ceramic substrate due to the thickening of the copper-based plate material. In this regard, in the copper-based plate material of the present invention, after a first heating test of heating at 300°C for 1 hour, the proportion of the area of ​​crystal grains oriented within 20° of the Cube orientation on the surface of the copper-based plate material is greater than the proportion of the area of ​​crystal grains oriented within 20° of the R orientation. As a result, the absolute value of Young's modulus before the heating test is reduced, and the change in Young's modulus before and after the first heating test, which simulates the operation of the power module, is also reduced. Therefore, thermal stress during thermal cycling between room temperature and around 300°C can be controlled, making it less likely for delamination to occur at the bonding interface with the ceramic substrate when the power module is in operation.

[0027] Therefore, by adopting the above configuration, the present invention can provide a copper-based plate material that can suppress grain coarsening and improve bonding properties with ceramics when heated in a temperature range from relatively low temperatures of around 300°C to high temperatures of around 1000°C, and can also suppress an increase in Young's modulus, thereby making it less likely for delamination due to thermal stress at the bonding interface to occur when bonding to a ceramic substrate or when operating a heat dissipation substrate bonded to a ceramic substrate.

[0028] [1] Composition of Copper-Based Sheet Material The copper-based sheet material of the present invention is composed of so-called pure copper containing 99.99% by mass or more of copper (Cu). This increases the thermal conductivity and electrical conductivity of the copper-based sheet material and reduces the Young's modulus, allowing it to exhibit particularly excellent performance as a conductive portion of a heat dissipation substrate. On the other hand, if the copper (Cu) content is less than 99.99% by mass, the thermal conductivity (or electrical conductivity) of the copper-based sheet material decreases, making it unsuitable as a conductive portion of a heat dissipation substrate. Furthermore, if the copper (Cu) content is less than 99.99% by mass, the orientation of crystal grains toward the Cube orientation in the metal structure becomes difficult, and the Young's modulus of the copper-based sheet material also increases. Therefore, the copper-based sheet material needs to contain 99.99% by mass or more of copper (Cu).

[0029] Furthermore, the copper-based plate material of the present invention contains at least one additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), in a total amount of 11 ppm by mass or more and 40 ppm by mass or less. These additive elements are intentionally added to improve properties and can suppress the decrease in crystal grains oriented in the cube direction and the increase in crystal grains oriented in the R direction due to primary recrystallization after heating at 300°C for 1 hour. Here, if the total content of these additive elements is less than 11 ppm by mass, after the first heating test of heating at 300°C for 1 hour, the number of crystal grains oriented in the cube direction decreases and the number of crystal grains oriented in the R direction increases, so the percentage of the area of ​​crystal grains oriented within 20° of the R direction Y １ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X １ The ratio becomes smaller. On the other hand, when the total content of these additive elements exceeds 40 ppm by mass, after a second heating test of heating at 1000°C for 1 hour, secondary recrystallization reduces the number of crystal grains oriented in the Cube direction and increases the number of crystal grains oriented in the R direction, thus reducing the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y. ２ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X ２ Therefore, the ratio of the area of ​​crystal grains oriented within 20° from the R direction Y after the first heating test is smaller.１ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X １ In addition to increasing the ratio of the area of ​​crystal grains oriented within 20° from the R orientation after the second heating test, Y ２ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X ２ From the perspective of increasing the concentration, it is preferable that the total content of at least one additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) be in the range of 15 ppm by mass or more and 37 ppm by mass or less.

[0030] In the copper-based plate material of the present invention, it is preferable to strictly control the content of impurity elements other than the additive elements, in addition to the additive elements mentioned above. Here, the impurity elements may include one or more selected from the group consisting of silver (Ag), sulfur (S), nickel (Ni), arsenic (As), selenium (Se), and oxygen (O), each present in an amount greater than 0 ppm by mass. On the other hand, the ratio Y of the area of ​​crystal grains oriented within 20° from the R orientation after the first heating test. １ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X １ In addition to further increasing the size of the crystal grains, the ratio of the area of ​​crystal grains oriented within 20° of the R orientation Y after the second heating test. ２ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X ２From the viewpoint of further increasing the content, the silver (Ag) content can be, for example, 20 ppm by mass or less, preferably 16 ppm by mass or less, and more preferably 14 ppm by mass or less. The sulfur (S) content can be, for example, 12 ppm by mass or less, preferably 10 ppm by mass or less, and more preferably 8 ppm by mass or less. The nickel (Ni) content can be, for example, 1.5 ppm by mass or less, preferably 1.0 ppm by mass or less, and more preferably 0.8 ppm by mass or less. The arsenic (As) content can be, for example, 1.0 ppm by mass or less, preferably 0.5 ppm by mass or less, and more preferably 0.4 ppm by mass or less. The selenium (Se) content can be, for example, 1.5 ppm by mass or less, preferably 0.5 ppm by mass or less, and more preferably 0.4 ppm by mass or less. Furthermore, the oxygen (O) content can be, for example, 15 ppm by mass or less, preferably 10 ppm by mass or less, and more preferably 8 ppm by mass or less. In particular, the ratio of the area of ​​crystal grains oriented within 20° from the R direction after the second heating test, without impairing the high conductivity of pure copper, Y ２ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to X ２ From the viewpoint of further increasing the resistivity and controlling the residual resistivity ratio to a desired range, it is preferable that the silver (Ag) content is 16 ppm by mass or less, the sulfur (S) content is 10 ppm by mass or less, the nickel (Ni) content is 1.0 ppm by mass or less, the arsenic (As) content is 0.5 ppm by mass or less, the selenium (Se) content is 0.5 ppm by mass or less, and the oxygen (O) content is 10 ppm by mass or less. These components may be included as impurities or as additives.

[0031] In this specification, "impurities" refers to at least one of the elements present in the raw materials of copper-based sheet materials and the elements that are introduced during the manufacturing process of copper-based sheet materials.

[0032] The content of each component in copper-based sheet materials can be measured, for example, using glow discharge mass spectrometry (GDMS).

[0033] [2] The ratio of the area of ​​crystal grains oriented within 20° from the Cube orientation and within 20° from the R orientation to the area of ​​the measurement region. In the crystal orientation analysis performed on the surface of the copper plate material of the present invention by the EBSD method after the first heating test of heating at 300°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> Cube orientation to the area of ​​the measurement region is X １ Let Y be the ratio of the area of ​​crystal grains oriented within 20° from the R direction of {231}<346>. １ In that case, X １ Y １ It is configured to be larger. Furthermore, in the crystal orientation analysis performed on the surface of the copper-based plate material of the present invention by the EBSD method after a second heating test in which it was heated at 1000°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region was X ２ Let Y be the ratio of the area of ​​crystal grains oriented within 20° of the R direction. ２ In that case, X ２ Y ２ It is configured to become larger.

[0034] The inventors investigated the temperature- and grain growth behavior of pure copper-based materials and found that the crystal orientation of copper-based plate materials tends to change significantly when heated at 300°C and 1000°C compared to when heated at lower temperatures.

[0035] Of these, 300°C is the temperature at which primary recrystallization occurs in pure copper-based materials. At this temperature, most of the crystal orientations that were oriented in the Cube direction before heating disappear, and instead, the number of crystal orientations oriented in the R direction begins to increase. In this regard, the copper-based plate material of the present invention contains additive elements selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) in a total amount of 11 ppm by mass or more and 40 ppm by mass or less. By manufacturing the copper-based plate material under appropriate conditions, even after performing a first heating test of heating at 300°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> Cube direction X １ Y is the ratio of the area of ​​crystal grains oriented within 20° from the R direction of {231}<346>. １ It can be made larger. Therefore, even when there is no addition of additive elements selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), or when the types and contents of these additive elements differ from those described above, the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation X １ The ratio of the area of ​​crystal grains oriented within 20° from the R direction Y becomes smaller. １ It gets bigger.

[0036] On the other hand, 1000°C is the temperature range for secondary recrystallization, in which crystal grains coarse. In general pure copper-based materials, there are almost no crystal grains oriented in the Cube direction, and crystal grains oriented in the R direction occupy the majority. However, in the copper-based plate material of the present invention, by containing an additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) in a total amount of 11 mass ppm to 40 mass ppm, and by manufacturing the copper-based plate material under appropriate conditions, primary recrystallization is suppressed when a first heating test is performed at 300°C, making it less likely for the crystal orientation that was oriented in the Cube direction to decrease. At the same time, when a second heating test is performed at 1000°C, crystal grains oriented in the Cube direction grow preferentially due to secondary recrystallization, so the ratio of the area of ​​crystal grains oriented within 20° of the Cube direction X ２ Y is the ratio of the area of ​​crystal grains oriented within 20° from the R direction. ２ It can be made larger compared to [this].

[0037] In particular, after performing a second heating test at 1000°C for 1 hour, the percentage of the area of ​​crystal grains oriented within 20° of the cube orientation X ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２ By being larger than the above, the growth of crystal grains due to heating is suppressed, and the increase in Young's modulus compared to before heating can be reduced. On the other hand, the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation X ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２ If the grain size is smaller than the average grain size, when heated to 1000°C, the grains oriented in the R direction grow rapidly, resulting in a larger average grain size and reduced bonding strength with ceramics.

[0038] Therefore, the ratio X of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region after the first heating test is... １ [%] and the ratio Y of the area of ​​crystal grains with a deviation angle of 20° or less from the R orientation. １When Y is expressed as [%], １ X １ The ratio (X １ / Y １ ) is configured to be greater than 1.0, preferably 2.0 or greater.

[0039] Furthermore, the ratio X of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region after the second heating test. ２ [%] and the ratio Y of the area of ​​crystal grains with a deviation angle of 20° or less from the R orientation. ２ When Y is expressed as [%], ２ X ２ The ratio (X ２ / Y ２ ) is configured to be greater than 1.0, preferably 2.0 or greater.

[0040] Furthermore, in the crystal orientation analysis performed on the surface of the copper-based plate material of the present invention using the EBSD method before the first and second heating tests, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation was determined to be X ０ When 、 X ０ It is preferable that X is 40% or more of the area of ​​the measurement region. Here, X ０ If the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region is less than 40%, the Young's modulus of the copper-based plate material increases, leading to increased thermal stress when bonded to a ceramic substrate, which makes delamination more likely at the bonding interface. Therefore, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region X ０ The lower limit is preferably 40% or more, and more preferably 50% or more. On the other hand, the ratio X of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region. ０ While there is no particular upper limit, for example, from the perspective of suppressing the decrease in the tensile strength and elongation of copper-based sheet materials and improving their suitability for a wider range of applications, it may be set to 98% or less.

[0041] Here, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region can be obtained from crystal orientation analysis data calculated using analysis software (TSL Corporation, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning electron microscope (JEOL Ltd., JSM-7001FA). "EBSD" is an abbreviation for Electron BackScatter Diffraction, a crystal orientation analysis technique that utilizes backscattered electron Kikuchi line diffraction that occurs when an electron beam is irradiated onto a copper plate sample in a scanning electron microscope (SEM). "OIM Analysis" is analysis software for data measured by EBSD. The measurement can be performed on the surface of a copper plate material that has been mirror-finished by electropolishing. For example, if the copper plate material is a rolled material, the measurement can be performed on the mirror-finished rolled surface. The measurement area on the surface of the copper-based plate material is approximately 1600 μm × approximately 3000 μm, and measurements can be performed with a scan step size of 1.0 μm. From the crystal orientation data of this measurement area, the total area of ​​crystal grains with a deviation angle of 20° or less from the cube orientation of {100}<001>, which is the ideal orientation, can be determined. By dividing this total area by the area of ​​the measurement area, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation can be determined. Here, it is preferable to use the average value obtained by measuring the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement area in three or more different measurement areas on the same test material.

[0042] On the other hand, the ratio of the area of ​​crystal grains oriented within 20° of the R orientation to the area of ​​the measurement region can be determined in the same way as the ratio of the area of ​​crystal grains oriented within 20° of the Cube orientation to the area of ​​the measurement region.

[0043] [3] Residual Resistivity Ratio The copper-based sheet material of the present invention preferably has a residual resistance ratio in the range of 75 to 220 after the first heating test and the second heating test, and more preferably in the range of 100 to 180. This makes it possible to obtain a copper-based sheet material that can be more suitably used as a heat dissipation material without reducing electrical conductivity or thermal conductivity, and in particular, it makes it even less likely for the grain size to coarse after the second heating test to occur. Furthermore, by controlling the residual resistance ratio within this range, the amount of solid solution and precipitation of elements other than copper (Cu) in the copper (Cu) matrix is ​​controlled, so the change in crystal orientation before and after the heating test can be further reduced. Here, one way to control the residual resistance ratio of the copper-based sheet material is to control the content of compounds formed by the reaction of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) with one or both of sulfur (S) and oxygen (O). Furthermore, controlling the content of silver (Ag), sulfur (S), nickel (Ni), arsenic (As), selenium (Se), and oxygen (O) in copper-based sheet materials is also effective in controlling the residual resistance ratio.

[0044] The residual resistance ratio (RRR) of a copper-based sheet material is calculated, for example, using the four-terminal method, based on the electrical resistance ρ of the copper-based sheet material at room temperature (293K). ２９３Ｋ And the electrical resistance ρ of copper-based plate material in liquid helium (4.2K) ４．２Ｋ The obtained ρ ２９３Ｋ and ρ ４．２Ｋ Therefore, RRR = ρ ２９３Ｋ / ρ ４．２Ｋ It can be calculated using the following formula.

[0045] [7] Plate Thickness The plate thickness of the copper-based plate material of the present invention is not particularly limited, but can be in the range of 0.1 mm to 4.0 mm or 0.8 mm to 4.0 mm. The copper-based plate material of the present invention makes it less likely for delamination to occur at the joint even when a thick copper plate of 0.8 mm or more is bonded to a ceramic substrate.

[0046] [8] Method for manufacturing copper-based sheet materials The copper-based sheet materials described above can be realized by controlling the combination of composition and manufacturing process, and the manufacturing process is not particularly limited. Among these, the following method can be cited as an example of a manufacturing process that can obtain a copper-based sheet material that suppresses grain coarsening and improves bonding with ceramics, and also suppresses the increase in Young's modulus and suppresses the generation of thermal stress.

[0047] An example of a method for manufacturing copper-based sheet material according to the present invention involves combining multiple raw materials to obtain a copper raw material with a composition equivalent to that of the above-described copper-based sheet material, and then sequentially performing a melting and casting process [Step 1], a continuous two-stage heat treatment process [Step 2], a hot rolling process [Step 3], a cold rolling process [Step 4], a recrystallization annealing process [Step 5], and a temper rolling process [Step 6] on the copper raw material. In this manufacturing method, in particular, by performing the continuous two-stage heat treatment process [Step 2] after the melting and casting process [Step 1], the solid solution precipitation state of additive elements and impurities can be controlled. As a result, even after a heating test is performed on the obtained copper-based sheet material, the proportion of the area of ​​crystal grains oriented within 20° of the Cube orientation can be controlled to be greater than the proportion of the area of ​​crystal grains oriented within 20° of the R orientation.

[0048] (i) Melting and casting process [Step 1] The melting and casting process [Step 1] involves melting a copper raw material to which additive elements have been added to have the same composition as described above, and casting it to produce a copper ingot of a predetermined shape. In the melting and casting process [Step 1], it is preferable to melt and cast the copper raw material using a high-frequency melting furnace.

[0049] (ii) Continuous two-stage heat treatment process [Process 2] The continuous two-stage heat treatment process [Process 2] is a process in which two stages of heat treatment are performed consecutively on the ingot after the casting process [Process 1] has been carried out.

[0050] In the continuous two-stage heat treatment process [Step 2], the heat treatment conditions are preferably such that, as the first heat treatment, heat treatment is performed at a target temperature of 850°C to 1000°C for a holding time of 10 minutes to 10 hours, and then the temperature is lowered in the same furnace to a target temperature of 400°C to 800°C, and as the second heat treatment, heat treatment is performed at this target temperature of 400°C to 800°C for a holding time of 10 minutes to 5 hours. By performing such first and second heat treatments, the solid solution precipitation state of additive elements and impurities can be controlled, so that even after heating tests, i.e., the first and second heating tests, are performed on the crystal grains contained in the resulting copper-based plate material, the proportion of the area of ​​crystal grains oriented within 20° of the Cube orientation can be controlled to be greater than the proportion of the area of ​​crystal grains oriented within 20° of the R orientation. More specifically, the first heat treatment can homogenize the additive elements and impurities that were segregated due to the melting and casting process [Step 1] by solid solution. Subsequently, by cooling and performing a second heat treatment, the temperature is adjusted to the precipitation temperature range, thereby obtaining a metallic structure in which precipitates are uniformly deposited.

[0051] If the first heat treatment is not performed, or if the temperature reached during the first heat treatment is less than 850°C, or if the holding time is less than 10 minutes, the added elements and impurities will not be sufficiently dissolved and will segregate, resulting in a non-uniform crystal structure. Furthermore, if the temperature reached during the first heat treatment is higher than 1000°C, or if the holding time is longer than 10 hours, the surface oxide film will become thicker, which increases the amount of surface material removed after the hot rolling process [step 3] described later, thus reducing the yield, which is undesirable.

[0052] Furthermore, if the second heat treatment is not performed, or if the temperature reached during the second heat treatment is less than 400°C, or if the holding time is less than 10 minutes, the precipitation of the additive elements and impurity elements dissolved in the first heat treatment will not proceed sufficiently, making it difficult for the crystal grains oriented in the cube orientation to develop through recrystallization in the recrystallization annealing process [step 5] described later, which is undesirable. Also, if the temperature reached during the second heat treatment is higher than 800°C, the precipitation of the additive elements and impurity elements will not proceed sufficiently because the temperature reached will be above the precipitation temperature, which is undesirable for the same reasons as when the temperature reached during the second heat treatment is less than 400°C. In addition, if the holding time during the second heat treatment is longer than 5 hours, especially longer than 10 hours, it is the same as when the temperature reached during the second heat treatment is less than 400°C.

[0053] (iii) Hot Rolling Process [Process 3] The hot rolling process [Process 3] is a process in which the ingot that has undergone the continuous two-stage heat treatment process [Process 2] is hot-rolled to a predetermined thickness to produce a hot-rolled material. The conditions for the hot rolling process [Process 3] can be set to conditions in which dynamic recrystallization occurs. For example, at the temperature reached in the second heat treatment described above, the total reduction rate can be set to a range of 50% to 99%. By performing the hot rolling process [Process 3], the precipitates formed in the continuous two-stage heat treatment process [Process 2] described above become dynamic recrystallization sites, making recrystallization more likely and thus making the metal structure more homogeneous. If the continuous two-stage heat treatment process [Step 2] is not performed, the crystalline structure after the hot rolling process [Step 3] will be heterogeneous. As a result, when the obtained copper-based sheet material is subjected to heating tests at temperatures of 300°C or 1000°C, further grain growth is more likely to occur. Furthermore, when the heating test is performed, the proportion of the area of ​​grains oriented within 20° of the Cube orientation tends to be smaller than the proportion of the area of ​​grains oriented within 20° of the R orientation.

[0054] In this specification, the "processing rate" (reduction rate) is the value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the result by the cross-sectional area before rolling, multiplying by 100, and expressing it as a percentage. It is expressed by the following formula: [Processing Rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} × 100 (%)

[0055] After the hot rolling process [Step 3], the hot-rolled material may be cooled by water cooling and then surface-machined. Surface machining can remove surface oxide films and defects generated during the hot rolling process [Step 3]. The surface machining conditions can be any conditions that are normally used and are not particularly limited. The amount removed from the surface of the hot-rolled material by surface machining can be appropriately adjusted based on the oxidation state of the surface, for example, to about 1 mm to 5 mm from the surface of the hot-rolled material.

[0056] (iv) Cold Rolling Process [Process 4] The cold rolling process [Process 4] is a process in which the hot-rolled material after the hot rolling process [Process 3] is subjected to cold rolling. The total processing rate in the cold rolling process [Process 4] is preferably 65% ​​or more. If the total processing rate is less than 65%, the rolled texture will not develop sufficiently, making it difficult for crystal grains oriented in the cube orientation to develop in the recrystallization annealing process [Process 5] described later, which is undesirable. On the other hand, there is no particular upper limit to the total processing rate in the cold rolling process [Process 4], but from the viewpoint of suppressing heat generation due to processing, it is preferably 98% or less.

[0057] (v) Recrystallization annealing process [Step 5] The recrystallization annealing process [Step 5] is a process in which the cold-rolled material after the cold-rolling process [Step 4] is subjected to heat treatment to recrystallize it. Here, the heat treatment conditions in the recrystallization annealing process [Step 5] are such that the target temperature is in the range of 200°C to 650°C, and the holding time at the target temperature is in the range of 30 seconds to 5 hours. Here, if the target temperature is less than 200°C or the holding time is less than 30 seconds, recrystallization will not occur sufficiently, and the crystal grains oriented in the cube direction in the copper-based plate material will not develop sufficiently, which is undesirable from the viewpoint of making it difficult to suppress the increase in Young's modulus and suppress the generation of thermal stress. On the other hand, if the target temperature exceeds 650°C or the holding time exceeds 5 hours, it is undesirable from the viewpoint of the crystal grains becoming coarse and the bonding ability with ceramics decreasing.

[0058] (vi) Temper rolling process [Process 6] The temper rolling process [Process 6] is a process in which the cold-rolled material after the recrystallization annealing process [Process 5] is further cold-rolled in order to adjust the material strength, and can be performed at will. Here, the total processing rate in the temper rolling process [Process 6] can be set according to the desired material strength of the copper sheet material, and is preferably in the range of more than 0% and 35% or less. If the total processing rate is greater than 35%, it is undesirable from the viewpoint that the proportion of crystal grains oriented in the cube orientation on the rolled surface of the copper sheet material decreases. Note that the temper rolling process [Process 6] may be omitted if material strength is not required for the resulting copper sheet material.

[0059] [9] Applications of copper-based sheet material The copper-based sheet material of the present invention can be suitably used not only as a heat dissipation substrate in which a ceramic substrate is bonded to a copper sheet by heat treatment at 800°C or higher, but also as a heat spreader for power modules and a spacer on a chip. The reason for this is that these components are sometimes joined by soldering, and the copper-based sheet material of the present invention suppresses the growth of crystal grains even at around 300°C, which is the mounting temperature for soldering, and the crystal orientation is largely oriented in the cube orientation, so the bonding strength by soldering can be increased. Furthermore, since the copper-based sheet material of the present invention can be suitably used for bonding by soldering, it is also preferable to use it in applications such as busbars, flat wires, and round wires obtained by drawing the flat wire, which are slit into long, narrow strips depending on the type and shape of the heating element.

[0060] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concept and claims of the present invention, and can be modified in various ways within the scope of the present invention.

[0061] Next, in order to further clarify the effects of the present invention, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples.

[0062] (Examples 1-14 of the present invention, Comparative Examples 1-13 and 16) Using a high-frequency induction melting furnace, copper raw materials and additive elements were melted according to the compositions shown in Table 1, and a melting and casting process [Step 1] was performed to cast copper ingots having various compositions. These ingots were subjected to a heat treatment (first heat treatment) at the temperatures and holding times shown in Table 2, followed by a continuous two-stage heat treatment process [Step 2] in which a heat treatment (second heat treatment) was performed in the same furnace at the temperatures and holding times shown in Table 2. Next, a hot rolling process [Step 3] was performed in which the ingots were rolled so that the longitudinal direction was the rolling direction, resulting in a total processing rate of 90%, to obtain hot-rolled material.

[0063] After cooling, the hot-rolled material was surface-machined to remove approximately 1 mm to 3 mm from both the front and back surfaces to remove the surface oxide film. Then, in the cold-rolling process [Step 4], the hot-rolled material was rolled so that the longitudinal direction of the hot-rolled material was the rolling direction, resulting in a total processing rate of 80%.

[0064] After the cold rolling process [step 4], the cold-rolled material was subjected to a recrystallization annealing process [step 5], in which it underwent heat treatment at a target temperature (heat treatment temperature) of 500°C for a holding time (heat treatment time) of 2 hours. Next, a temper rolling process [step 6] was performed in which the material was rolled with the longitudinal direction being the rolling direction so that the total processing rate was 20%, thereby obtaining a copper-based sheet material with a thickness of 1.0 mm.

[0065] In Table 1, manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y) are listed as additive elements among the constituent components of copper-based sheet materials other than copper (Cu). Silver (Ag), sulfur (S), nickel (Ni), arsenic (As), selenium (Se), and oxygen (O) are considered impurities. For example, in the present invention example and comparative example, electrolytic copper is used as a raw material, and approximately 1 ppm to 8 ppm of sulfur (S) is present, derived from the electrolytic copper. In Table 1, a horizontal line "-" is indicated in the column for components not contained in the copper-based sheet material, indicating that the component is either not present or, if present, is below the detection limit.

[0066] (Comparative Example 14) A second heat treatment was performed on an ingot obtained by the same method as in Examples 1 to 14 of the present invention, without performing the first heat treatment, at the temperature and holding time (second heat treatment conditions) shown in Table 2 in the furnace, and then a hot rolling process [step 3] was performed under the same conditions as in Examples 1 to 14 of the present invention to obtain a hot-rolled material.

[0067] After cooling, the hot-rolled material was surface-machined to remove approximately 1 mm to 3 mm from both the front and back surfaces to remove the surface oxide film. Then, under the same conditions as in Examples 1 to 14 of the present invention, a cold rolling process [step 4], a recrystallization annealing process [step 5], and a temper rolling process [step 6] were performed to obtain a copper-based sheet material.

[0068] (Comparative Example 15) A first heat treatment was performed on an ingot obtained by the same method as in Examples 1 to 14 of the present invention, with the target temperature and holding time (first heat treatment conditions) shown in Table 2, and then a hot rolling process [step 3] was performed under the same conditions as in Examples 1 to 14 of the present invention to obtain a hot-rolled material.

[0069] After cooling, the hot-rolled material was surface-machined to remove approximately 1 mm to 3 mm from both the front and back surfaces to remove the surface oxide film. Then, under the same conditions as in Examples 1 to 14 of the present invention, a cold rolling process [step 4], a recrystallization annealing process [step 5], and a temper rolling process [step 6] were performed to obtain a copper-based sheet material.

[0070] [Various Measurement and Evaluation Methods] The following characteristic evaluations were performed using the copper-based plate materials according to the above-described examples and comparative examples of the present invention. The evaluation conditions for each characteristic are as follows.

[0071] [1] Composition of copper-based sheet material The content of each component in the copper-based sheet material was measured using glow discharge mass spectrometry (GDMS). The results are shown in Table 1.

[0072] [2] Ratio of the area of ​​crystal grains oriented within 20° of the Cube orientation and within 20° of the R orientation to the area of ​​the measurement region The ratio of the area of ​​crystal grains oriented within 20° of the Cube orientation to the area of ​​the measurement region was obtained from crystal orientation analysis data calculated using analysis software (TSL, OIM Analysis) from crystal orientation data measured continuously using an EBSD detector attached to a high-resolution scanning electron microscope (JEOL Ltd., JSM-7001FA) for each of the following: the test material made of copper-based plate material obtained in the present invention example and comparative example before the heating test, the test material after the first heating test of heating at 300°C for 1 hour, and the test material after the second heating test of heating at 1000°C for 1 hour. Measurements were performed on samples of copper-based sheet material with a mirror-finished surface (rolled surface) achieved by electropolishing, within a measurement area of ​​approximately 1600 μm × 3000 μm, using a scan step size of 1.0 μm.

[0073] From the crystal orientation data obtained by the EBSD method, crystal grains with a deviation angle of 20° or less from the {100}<001> cube orientation were considered crystal grains oriented in the cube orientation. The total area of ​​these grains was calculated, and the area ratio of crystal grains oriented in the cube orientation was obtained by dividing this total area by the area of ​​the measurement region. Furthermore, from the crystal orientation data obtained by this EBSD method, crystal grains with a deviation angle of 20° or less from the {231}<346> R orientation were considered crystal grains oriented in the R orientation. The total area of ​​these grains was calculated, and the area ratio of crystal grains oriented in the R orientation was obtained by dividing this total area by the area of ​​the measurement region. The area ratios of crystal grains oriented in the cube direction and the area ratios of crystal grains oriented in the R direction were determined by measuring these areas in three or more different measurement areas on the same test material. The average of these three or more area ratios was then used as the measured value for the area ratios of crystal grains oriented in the cube direction and the area ratios of crystal grains oriented in the R direction.

[0074] In this way, the ratio X of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation to the area of ​​the measurement region in the test material before the heating test is determined.０ The ratio X [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. ０ Also, after the first heating test, the ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. ０ to Y ０ of X ０ / Y ０ is obtained.

[0075] In addition, after the first heating test, the ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. １ The ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. １ Also, after the first heating test, the ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. １ to Y １ of X １ / Y １ is obtained.

[0076] In addition, after the second heating test, the ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. The results are shown in Table 3. ２ The ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {100}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. ２ Also, after the second heating test, the ratio X [%] of the area of crystal grains oriented within 20° from the Cube orientation of {!00}<001> to the area of the measurement region in the test material and the ratio Y [%] of the area of crystal grains having a deviation angle of 20° or less from the R orientation of {231}<346> are each determined, and the ratio (X / Y) of X to Y is obtained. ２ to Y ２ of X ２ / Y ２ is obtained. The results are shown in Table 3.

[0077] [3] Measurement of Residual Resistance Ratio The residual resistance ratio (RRR) of the copper-based sheet material is measured for each of the test materials after the first heating test of heating the copper-based sheet material obtained in the examples and comparative examples of the present invention at 300°C for 1 hour and after the second heating test of heating at 1000°C for 1 hour. Using the four-terminal method, the electrical resistance ρ of the copper-based sheet material at room temperature (293 K) and the electrical resistance ρ of the copper-based sheet material under liquid helium (4.2 K) are measured, and from the obtained ρ and ρ, RRR = ρ / ρ is calculated by the formula. The results are shown in Table 4. ２９３Ｋ and the electrical resistance ρ of the copper-based sheet material under liquid helium (4.2 K) ４．２Ｋ are measured, and from the obtained ρ ２９３Ｋ and ρ ４．２Ｋ RRR = ρ ２９３Ｋ / ρ ４．２Ｋ is calculated by the formula. The results are shown in Table 4.

[0078] [4] Measurement of Average Crystal Grain Size The average crystal grain size of the copper-based sheet material was determined by the cutting method specified in JIS H0501. More specifically, the surface (rolled surface) of the copper-based sheet material after the second heating test, in which it was heated at 1000°C for 1 hour, was polished to a mirror finish by wet polishing and buffing, and the polished surface was corroded with a weak acid solution for several seconds. The surface was then observed at 12.5x magnification using an optical microscope (OM). In the resulting optical microscope (OM) image, ten line segments with a length of 5000 μm were drawn in directions parallel and perpendicular to the rolling direction. The total number of points where each line segment intersects with the crystal grain boundary was counted, and the average length of each section of the line segment demarcated by the crystal grain boundary was calculated using the following formula (I), thereby determining the average crystal grain size (μm), which is the average length of each section of the line segment. Average length of each section of the line segment [μm] = 5000 [μm] × 20 / (total number of intersections between the line segment and grain boundaries) ... (I)

[0079] The average grain size measurements obtained after the second heating test were evaluated according to the following evaluation criteria. The results are shown in Table 4. "◎" (Excellent): The average grain size after the second heating test is 400 μm or less. "〇" (Good): The average grain size after the second heating test is greater than 400 μm and 600 μm or less. "×" (Unacceptable): The average grain size after the second heating test is greater than 600 μm.

[0080] [5] Measurement and Evaluation of Young's Modulus The Young's modulus of copper-based sheet materials was measured by taking nine strip-shaped test pieces, each 10 mm wide and 42 mm long, from the copper-based sheet materials of the present invention example and comparative example, along the rolling direction, and measuring the Young's modulus using the free resonance method with a high-precision general-purpose Young's modulus / internal friction measuring device (manufactured by Nippon Techno Plus Co., Ltd., model number: JE-RT). Here, the Young's modulus of three test materials that had not undergone the heating test was measured, and the average of the three Young's moduli was calculated to obtain the measured value of Young's modulus before heating (a). In addition, the Young's modulus of the other three test materials was measured after a first heating test of heating at 300°C for 1 hour, and the average of the three Young's moduli was calculated to obtain the measured value of Young's modulus after the first heating test (b). In addition, the Young's modulus of the remaining three test materials was measured after a second heating test of heating at 1000°C for 1 hour, and the average of the three Young's moduli was calculated to obtain the measured value of Young's modulus after the second heating test (c).

[0081] The measured Young's modulus before heating (a), the measured Young's modulus after the first heating test (b), and the measured Young's modulus after the second heating test (c) were used to determine the absolute values ​​of the change in Young's modulus before and after the first heating test (b-a) and the change in Young's modulus before and after the second heating test (c-a). These values ​​were then evaluated according to the following criteria. The results are shown in Table 4. "◎" (Excellent): The measured Young's modulus before heating (a) is 110 GPa or less, and the absolute values ​​of the change in Young's modulus before and after the first heating test (b-a) and the absolute values ​​of the change in Young's modulus before and after the second heating test (c-a) are both 5 GPa or less. "〇" (Good): The measured Young's modulus before heating (a) is 110 GPa or less, and the absolute values ​​of the change in Young's modulus before and after the first heating test (b-a) and the absolute values ​​of the change in Young's modulus before and after the second heating test (c-a) are both 15 GPa or less (except in cases where the evaluation is "◎"). "×" (Not acceptable): If the measured value of Young's modulus before heating (a) is greater than 110 GPa, or if at least one of the absolute values ​​of the change in Young's modulus before and after the first heating test (b-a) and the absolute value of the change in Young's modulus before and after the second heating test (c-a) is greater than 15 GPa.

[0082] [6] Overall Evaluation If both the evaluation result for the average grain size after the second heating test and the evaluation result for the Young's modulus before heating and the change in Young's modulus before and after heating were evaluated as "◎", the overall evaluation was evaluated as "◎", indicating that both of these characteristics are particularly excellent. Also, if at least one of the evaluation results for the average grain size after the second heating test and the evaluation result for the change in Young's modulus before and after heating were evaluated as "〇", and both of these evaluation results were evaluated as "◎" or "〇", the overall evaluation was evaluated as "〇", indicating that both of these characteristics are excellent. On the other hand, if at least one of the evaluation results for the average grain size after the second heating test and the evaluation result for the Young's modulus before heating and the change in Young's modulus before and after heating were evaluated as "×", the overall evaluation was evaluated as "×", indicating that at least one of these two characteristics is insufficient. The results are shown in Table 4.

[0083]

[0084]

[0085]

[0086]

[0087] From the results in Tables 1 to 4, the copper-based plate materials of Examples 1 to 14 of the present invention have a composition within the appropriate range for the present invention, and the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region on the surface of the copper-based plate material after the first heating test is X. １ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y １ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region on the surface of the copper-based plate material after the second heating test, X ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２It was larger. At this time, the copper-based plate materials of Examples 1 to 14 of the present invention were evaluated as "◎" or "〇" in an overall evaluation that combined the evaluation of the average grain size after the second heating test and the evaluation of the Young's modulus before heating and the amount of change in Young's modulus before and after the heating test.

[0088] Therefore, when the copper-based plate materials of Examples 1 to 14 of the present invention were heated in a temperature range from relatively low temperatures of around 300°C to high temperatures of around 1000°C, it was possible to suppress grain coarsening and improve bonding with ceramics, as well as suppress the increase in Young's modulus and suppress the generation of thermal stress.

[0089] In particular, in Examples 1 to 6 of the present invention, by containing one of manganese (Mn), tin (Sn), and zirconium (Zr) in a range of 13 ppm to 35 ppm, the Young's modulus before the heating test is reduced in all cases, and the surface of the copper-based plate material after the first heating test has a ratio of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region X １ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y １ Furthermore, the surface of the copper-based plate material after the second heating test was found to have a ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region. ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２ The size increased. At this time, it became easier to control the crystal orientation after the heating test, suppressing grain coarsening due to the heating test, and also suppressing the increase in Young's modulus due to the heating test.

[0090] Furthermore, in Examples 7 to 10 of the present invention, by including either chromium (Cr) or yttrium (Y) in a range of 18 ppm to 40 ppm, although controlling the residual resistance ratio and crystal orientation after the heating test was somewhat more difficult compared to Examples 1 to 6 of the present invention described above, it was possible to suppress grain coarsening due to the heating test and suppress the increase in Young's modulus due to the heating test.

[0091] Furthermore, in the present invention, examples 11 to 14 include two or more additive elements selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y). In this case as well, it was possible to suppress grain coarsening due to heating tests and to suppress the increase in Young's modulus due to heating tests.

[0092] On the other hand, the copper-based plate materials of Comparative Examples 1 to 23 have at least the ratio of the area of ​​crystal grains oriented within 20° from the cube orientation to the area of ​​the measurement region on the surface of the copper-based plate material after the first heating test X １ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y １ The ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region on the surface of a smaller copper plate material, or after a second heating test, X ２ However, the ratio of the area of ​​crystal grains oriented within 20° of the R direction Y ２ The size was smaller. Therefore, the copper-based plate materials of Comparative Examples 1 to 23 all received a "×" rating in their overall evaluation, which combined the evaluation of the average grain size after the second heating test and the evaluation of the Young's modulus before heating and the change in Young's modulus before and after the heating test.

Claims

1. A copper-based plate material containing 99.99% by mass or more of copper (Cu), and at least one additive element selected from the group consisting of manganese (Mn), tin (Sn), zirconium (Zr), chromium (Cr), and yttrium (Y), in a total amount of 11 ppm by mass or more and 40 ppm by mass or less, wherein, in a crystal orientation analysis by EBSD performed on the surface of the copper-based plate material after a first heating test in which the copper-based plate material was heated at 300°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° from the {100}<001> cube orientation to the area of ​​the measurement region is X １ Let Y be the ratio of the area of ​​crystal grains oriented within 20° from the R orientation of {231}<346>. １ In that case, X １ Y １ Furthermore, in a crystal orientation analysis performed on the surface of the copper-based plate material by the EBSD method after a second heating test in which the copper-based plate material was heated at 1000°C for 1 hour, the ratio of the area of ​​crystal grains oriented within 20° of the cube orientation to the area of ​​the measurement region is X ２ The ratio of the area of ​​crystal grains oriented within 20° of the R orientation is defined as Y. ２ In that case, X ２ Y ２ Larger copper-based sheet material.

2. In the crystal orientation analysis by the EBSD method performed on the surface of the copper-based sheet material before performing the first heating test and the second heating test, the ratio of the area of crystal grains oriented within 20° from the {100}<001> Cube orientation is X ０ When 、 X ０ is 40% or more with respect to the area of the measurement region, the copper-based sheet material according to claim 1.

3. The copper-based plate material according to claim 2, wherein the residual resistance ratio after the first heating test and the second heating test are both in the range of 75 to 220.

4. The copper-based sheet material according to claim 1, wherein the silver (Ag) content is 16 ppm by mass or less, the sulfur (S) content is 10 ppm by mass or less, the nickel (Ni) content is 1.0 ppm by mass or less, the arsenic (As) content is 0.5 ppm by mass or less, the selenium (Se) content is 0.5 ppm by mass or less, and the oxygen (O) content is 10 ppm by mass or less.

5. A heat dissipation substrate made of a copper-based plate material according to any one of claims 1 to 4.

6. A bus bar made of a copper-based plate material as described in any one of claims 1 to 4.

7. A rectangular wire made of copper-based sheet material according to any one of claims 1 to 4.

8. A round wire made of copper-based sheet material according to any one of claims 1 to 4.

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