Copper material and insulating substrate

Abstract

A copper material, wherein: the Cu content is in the range of 99.9-99.999 mass%; one or more group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, and Sb are contained in a total amount of 2-20 mass ppm; the electrical conductivity is 95% IACS or more; and area ratios S(110), S(311), S(331), S(210), S(321), and S(211) of respective crystal orientations in a plane orthogonal to the plate thickness direction satisfy S(110) + S(311) + S(331) + S(210) + S(211) > S(321).

Description

Copper material and insulating substrate

[0001] The present invention relates to a copper material suitable for electrical and electronic components such as heat sinks and thick copper circuits, and more particularly to a copper material used in insulating substrates for power semiconductors, and to an insulating substrate using this copper material. This application claims priority based on Japanese Patent Application No. 2024-192645, filed in Japan on November 1, 2024, the contents of which are incorporated herein by reference.

[0002] Traditionally, highly conductive copper materials have been used in electrical and electronic components such as heat sinks and thick copper circuits. Recently, with the increasing amount of current used in electrical and electronic equipment components, resistive heating has become a problem. In electronic devices such as semiconductor devices, for example, insulating substrates are used in which copper material is bonded to a ceramic substrate to form the aforementioned heat sinks and thick copper circuits.

[0003] When bonding ceramic substrates and copper materials, a high-temperature, high-pressure treatment is performed. This can lead to coarsening or uneven growth of the copper grain size, resulting in poor bonding, poor appearance, and problems during the inspection process. To solve this problem, the copper material is required to have minimal and uniform grain size changes even after heat treatment.

[0004] For example, Patent Documents 1 and 2 propose techniques for suppressing crystal growth in copper materials. Patent Document 1 states that by including 0.0006 to 0.0015 wt% of S, it is possible to adjust the crystal grain size to a certain level even when heat-treated at a temperature above the recrystallization temperature. Patent Document 2 states that by including Ca and specifying the ratio of Ca content to the total content of O, S, Se, and Te, it is possible to suppress the coarsening of crystal grains even when heat-treated at 800°C.

[0005] Japanese Patent Application Publication No. 06-002058 (A) International Publication No. 2020 / 203071

[0006] Incidentally, while Patent Documents 1 and 2 describe a configuration that suppresses grain coarsening by defining the composition, the properties change significantly depending on the amount of impurities dissolved in the copper matrix (copper purity), making it impossible to stably produce copper material and potentially leading to a significant decrease in productivity.

[0007] This invention has been made in view of the circumstances described above, and aims to provide a copper material that can stably exhibit the effect of suppressing grain coarsening when bonding a ceramic substrate and a copper material, even when the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, and that has stable properties, as well as an insulating substrate using this copper material.

[0008] To solve this problem, the inventors conducted diligent research and found that by controlling the microstructure of the copper material and the content of trace elements, it is possible to stably suppress the coarsening of crystal grains when bonding the ceramic substrate and the copper material, even when the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, and to provide a copper material with stable properties.

[0009] The present invention is based on the above-mentioned findings, and the copper material of embodiment 1 of the present invention has a Cu content in the range of 99.9 mass% or more and 99.999 mass% or less, and contains a total of 2 mass ppm of one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb The material contains a concentration of 95% IACS or higher, has an electrical conductivity of 95% IACS or higher, and satisfies the following equation (1) when the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> in a plane perpendicular to the thickness direction are S(110), S(311), S(331), S(210), S(321), and S(211), respectively: Equation (1): S(110) + S(311) + S(331) + S(210) + S(211) > S(321)

[0010] According to the copper material of embodiment 1 of the present invention, the Cu content is in the range of 99.9 mass% or more and 99.999 mass% or less, and the conductivity is 95% IACS or higher, so it has particularly excellent conductivity and heat dissipation properties and is particularly suitable as a material for components of electronic and electrical equipment used in high-current applications. Furthermore, it contains one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, and Sb in a total amount of 2 mass ppm to 20 mass ppm, and the area ratio of each crystal orientation in a plane perpendicular to the plate thickness direction satisfies equation (1) above. As a result, grain boundary movement can be stably suppressed, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing grain coarsening when joining the ceramic substrate and the copper material can be stably exhibited, and various properties remain stable.

[0011] The copper material of embodiment 2 of the present invention is characterized in that, in the copper material of embodiment 1, the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> in a plane perpendicular to the thickness direction are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and satisfy the following relationship. S(110) < 0.2 S(311) < 0.3 S(331) < 0.2 S(210) < 0.3 S(321) > 0.1 S(211) < 0.3 According to the copper material of embodiment 2 of the present invention, since the area ratio of each crystal orientation in a plane perpendicular to the plate thickness direction has the above-mentioned relationship, the movement of crystal grain boundaries can be suppressed even more stably, and even if the amount of impurities dissolved in the copper matrix (purity of copper) fluctuates, the effect of suppressing the coarsening of crystal grains when joining the ceramic substrate and the copper material can be exhibited even more stably, and various properties are stabilized.

[0012] The copper material of embodiment 3 of the present invention has an average grain size D in a plane perpendicular to the thickness direction in the copper material of embodiment 1 or embodiment 2. ａｖｅ For example, the crystal grain size is 2×D ａｖｅThe above is characterized in that the area ratio of the crystal grains is 10% or less. According to the copper material of embodiment 3 of the present invention, the average crystal grain size D ａｖｅ For example, the crystal grain size is 2×D ａｖｅ Since the area ratio of the above-mentioned crystal grains is 10% or less, there are not many coarse crystal grains, resulting in a uniform crystal structure and excellent properties.

[0013] The copper material of embodiment 4 of the present invention is characterized in that, in any one of the copper materials of embodiments 1 to 3, it contains one or more B group elements selected from Ca, Sr, and Ba in a total amount of 10 mass ppm to 200 mass ppm. According to the copper material of embodiment 4 of the present invention, since it contains one or more B group elements selected from Ca, Sr, and Ba in a total amount of 10 mass ppm to 200 mass ppm, a compound containing at least one of the B group elements and Cu is formed, and the pinning effect of this compound makes it possible to further reliably suppress grain growth during heat treatment.

[0014] An insulating substrate according to embodiment 5 of the present invention is an insulating substrate comprising a ceramic substrate and a copper plate bonded to at least one surface of the ceramic substrate, wherein the copper plate is made of one of the copper materials according to embodiments 1 to 4. According to the insulating substrate of embodiment 5 of the present invention, since the copper plate bonded to at least one surface of the ceramic substrate is made of one of the copper materials according to embodiments 1 to 4, grain growth during bonding is suppressed, a uniform crystalline structure is obtained, and it can be used stably.

[0015] The insulating substrate of embodiment 6 of the present invention is characterized in that, in the insulating substrate of embodiment 5 of the present invention, the ceramic substrate is one of silicon nitride, alumina, or aluminum nitride. According to the insulating substrate of embodiment 6 of the present invention, since the ceramic substrate is composed of one of silicon nitride, alumina, or aluminum nitride, the insulating properties of the ceramic substrate are excellent and it can be used stably.

[0016] The insulating substrate of embodiment 7 of the present invention is characterized in that, in the insulating substrate of embodiment 5 or embodiment 6 of the present invention, a plating layer is formed on the side of the copper plate opposite to the ceramic substrate. According to the insulating substrate of embodiment 7 of the present invention, since a plating layer is formed on the side of the copper plate opposite to the ceramic substrate, other members such as semiconductor elements and heat sinks can be well bonded to the copper plate, and various devices can be constructed.

[0017] According to the present invention, even when the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, it is possible to provide a copper material with stable properties that can stably exhibit the effect of suppressing grain coarsening when bonding a ceramic substrate and a copper material, and an insulating substrate using this copper material.

[0018] This is a schematic diagram illustrating an electronic device using an insulating substrate according to this embodiment. This is a flow chart of the manufacturing method of copper material according to this embodiment.

[0019] Below, a copper material and an insulating substrate, which are embodiments of one embodiment of the present invention, will be described with reference to the attached drawings. The copper material of this embodiment is used as a material for electrical and electronic components such as heat sinks and thick copper circuits, and is bonded to a ceramic substrate, for example, when forming the aforementioned electrical and electronic components to constitute an insulating substrate.

[0020] Figure 1 shows an insulating substrate 10 and an electronic device 1 using this insulating substrate 10, which are embodiments of the present invention. The electronic device 1 shown in Figure 1 comprises the insulating substrate 10 according to this embodiment, an electronic component 3 bonded to one side of the insulating substrate 10 (upper side in Figure 1) via a first solder layer 2, and a heat sink 51 bonded to the other side of the insulating substrate 10 (lower side in Figure 1) via a second solder layer 8. In this embodiment, the electronic component 3 is a power semiconductor element, and the electronic device 1 is a power module.

[0021] The insulating substrate 10 includes a ceramic substrate 11, a circuit layer 12 disposed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11, and a metal layer 13 disposed on the other surface (the lower surface in FIG. 1) of the ceramic substrate 11.

[0022] The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13. The ceramic substrate 11 is made of ceramics such as silicon nitride (Si ３ N ４ ), aluminum nitride (AlN), alumina (Al ２ O ３ ), etc. In this embodiment, the ceramic substrate 11 is made of silicon nitride (Si ３ N ４ ) which is particularly excellent in heat dissipation. Also, 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 in this embodiment, it is set to 0.32 mm.

[0023] The circuit layer 12 is formed by bonding a copper plate to one surface of the ceramic substrate 11. A circuit pattern is formed on this circuit layer 12, and one surface (the upper surface in FIG. 1) thereof is the mounting surface on which the electronic component 3 is mounted. Incidentally, it is preferable that a plating layer such as Ni or Ag is formed on the surface of the circuit layer 12 opposite to the ceramic substrate 11.

[0024] The metal layer 13 is formed by bonding a copper plate to the other surface of the ceramic substrate 11. This metal layer 13 has the effect of efficiently transmitting heat from the electronic component 3 to the heat sink 51. Incidentally, it is preferable that a plating layer such as Ni or Ag is formed on the surface of the metal layer 13 opposite to the ceramic substrate 11.

[0025] Here, the copper plate forming the circuit layer 12 and the ceramic substrate 11, and the copper plate forming the metal layer 13 and the ceramic substrate 11 are joined by existing joining methods such as the DBC method and the AMB method. The temperature during joining is, for example, a high temperature of 750°C or higher, which may cause grain coarsening in the circuit layer 12 and the metal layer 13.

[0026] Therefore, in this embodiment, the copper plate that forms the circuit layer 12 and the copper plate that forms the metal layer 13 are made of the copper material of this embodiment.

[0027] The copper material of this embodiment has a Cu content of 99.9 mass% or more and 99.999 mass% or less, and contains one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb in a total amount of 2 mass ppm or more and 20 mass ppm or less. In addition, the copper material of this embodiment may also contain one or more Group B elements selected from Ca, Sr, Ba in a total amount of 10 mass ppm or more and 200 mass ppm or less.

[0028] Furthermore, in the copper material of this embodiment, the conductivity is set to 95% IACS or higher. Although not particularly limited, the conductivity may be 102% IACS or lower.

[0029] In this embodiment of the copper material, the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> on the plane perpendicular to the thickness direction (rolled surface) are defined as S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and the following equation (1) is satisfied: (1) Equation: S(110) + S(311) + S(331) + S(210) + S(211) > S(321)

[0030] Also, in the copper material of the present embodiment, on the plane (rolling plane) orthogonal to the plate thickness direction, the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, <211> are preferably S(111), S(110), S(311), S(331), S(210), S(321), S(211), respectively, and satisfy the following relationships. 0.01 < S(110) < 0.2 0.01 < S(311) < 0.3 0.01 < S(331) < 0.2 0.01 < S(210) < 0.3 0.5 > S(321) > 0.1 0.01 < S(211) < 0.3

[0031] Further, in the copper material of the present embodiment, on the plane (rolling plane) orthogonal to the plate thickness direction, the average crystal grain diameter D ａｖｅ is such that the area ratio of crystal grains with a crystal grain diameter of 2×D ａｖｅ or more is preferably 10% or less.

[0032] Here, the reasons for defining the Cu content, the contents of various elements, the crystal orientation, the crystal grain diameter, and the conductivity in the copper material of the present embodiment as described above will be explained below.

[0033] (Cu content) In electrical and electronic components for high-current applications, in order to suppress heat generation during energization, it is required to have excellent electrical conductivity and heat dissipation. Therefore, it is preferable to use a copper material with high purity that is particularly excellent in electrical conductivity and heat dissipation. On the other hand, if the purity of copper is too high, there is a risk that crystal grains will easily coarsen in a high-temperature state. Therefore, in the copper material of the present embodiment, the Cu content is defined within the range of 99.9 mass% or more and 99.999 mass% or less. The lower limit of the Cu content is preferably 99.93 mass% or more, and more preferably 99.96 mass% or more. Also, the upper limit of the Cu content is preferably 99.998 mass% or less, and more preferably 99.997 mass% or less.

[0034] (Total content of one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb) One or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb, when present in the Cu matrix phase, will inhibit the movement of grain boundaries, and it becomes possible to suppress the coarsening of grains during heat treatment. Also, by defining the content of these Group A elements, it becomes possible to stabilize the properties. Here, if the total content of Group A elements is less than 2 mass ppm, there is a risk that the above-described effects cannot be obtained. On the other hand, if the total content of Group A elements exceeds 20 mass ppm, there is a risk that the recyclability as pure copper cannot be ensured. Therefore, in the copper material of the present embodiment, the total content of one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb is defined within the range of 2 mass ppm or more and 20 mass ppm or less. Note that the lower limit of the total content of the above-described Group A elements is preferably 4 mass ppm or more, and more preferably 6 mass ppm or more. Also, the upper limit of the total content of the above-described Group A elements is preferably 18 mass ppm or less, and more preferably 16 mass ppm or less.

[0035] (Total content of one or more B group elements selected from Ca, Sr, and Ba) One or more B group elements selected from Ca, Sr, and Ba have a very small solid solubility limit with Cu and form compounds with Cu. Therefore, by including B group elements, a compound that is stable even at high temperatures is formed. Furthermore, since this compound contains Cu, there is no risk of significantly reducing the thermal conductivity. Thus, by adding B group elements, it is possible to generate a compound that is stable at high temperatures, suppress grain boundary movement at high temperatures, and further suppress grain growth. On the other hand, if a large amount of B group elements is included, it may adversely affect manufacturability. For this reason, in the copper material of this embodiment, when B group elements are included, it is preferable to keep the total content of B group elements within the range of 10 mass ppm to 200 mass ppm. The lower limit of the total content of B group elements mentioned above is more preferably 15 mass ppm or more, and more preferably 20 mass ppm or more. Furthermore, the upper limit of the total content of the aforementioned group B elements is more preferably 150 mass ppm or less, and more preferably 100 mass ppm or less.

[0036] (Other unavoidable impurities) Other unavoidable impurities besides the elements mentioned above include As, B, Bi, Sc, V, Nb, Ta, Mo, W, Re, Ru, Os, Co, Rh, Ir, Pd, Pt, Au, Hg, Tl, N, Li, etc. These unavoidable impurities may be present in amounts that do not affect the properties.

[0037] (Conductivity) In electrical and electronic equipment components, excellent conductivity is required to suppress heat generation during current flow. For this reason, the copper material of this embodiment is specified to have a conductivity of 95% IACS or higher. Preferably, the conductivity of the copper material of this embodiment is 98% IACS or higher, and more preferably 100% IACS or higher.

[0038] (Area ratio of crystal orientations on a plane perpendicular to the thickness direction) In the copper material of this embodiment, the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> on a plane perpendicular to the thickness direction (rolled surface) are set to S(110), S(311), S(331), S(210), S(321), and S(211), respectively, so as to satisfy equation (1) above. As described above, by defining the area ratio of crystal orientations on a plane perpendicular to the thickness direction (rolled surface), the movement of crystal grain boundaries can be stably suppressed, and even if the amount of impurities dissolved in the copper matrix (purity of copper) fluctuates, the effect of suppressing the coarsening of crystal grains when joining the ceramic substrate and the copper material can be stably exhibited, and various properties are stabilized.

[0039] In this embodiment, if the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> on a plane perpendicular to the thickness direction (rolled surface) are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and the following relationships are satisfied, then the movement of crystal grain boundaries can be further stably suppressed, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing grain coarsening when joining the ceramic substrate and the copper material can be further stably exhibited, and various properties become stable. S(110) < 0.2 S(311) < 0.3 S(331) < 0.2 S(210) < 0.3 S(321) > 0.1 S(211) < 0.3

[0040] (Grain size) In the copper material of this embodiment, the average grain size D is measured on a plane perpendicular to the thickness direction (rolled surface). ａｖｅ For example, the crystal grain size is 2×D ａｖｅ When the area ratio of the above-mentioned crystal grains is 10% or less, there are not many coarse crystal grains, the grain size is relatively uniform, and the properties are stable. ａｖｅThe area ratio of the above crystal grains is more preferably 7% or less, and more preferably 5% or less. Furthermore, in the copper material of this embodiment, the average crystal grain size D ａｖｅ The particle size is preferably 400 μm or less, more preferably 300 μm or less, and even more preferably 250 μm or less.

[0041] Next, the method for manufacturing the copper material according to this embodiment, which has the above configuration, will be explained with reference to the flowchart shown in Figure 2.

[0042] (Melting and Casting Process S01) First, the molten copper obtained by melting oxygen-free copper raw material is adjusted by adding the aforementioned Group A elements and, if necessary, Group B elements. Individual elements or master alloys can be used for the addition of various elements. Alternatively, raw materials containing the above elements may be melted together with the copper raw material. Here, it is preferable that each element has a purity of 99.9 mass% or higher, known as 3N, or 99.99 mass% or higher, known as 4N. During melting, to reduce the hydrogen concentration, H ２ It is preferable to perform atmospheric melting in an inert gas atmosphere with a low vapor pressure of oxygen (e.g., Ar gas), and to minimize the holding time during melting. Then, the molten copper with adjusted composition is poured into a mold to produce an ingot. When considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0043] (Solidifying Heat Treatment Step S02) The obtained ingot is subjected to a solidifying heat treatment in order to homogenize the segregated components in the material. It is preferable that the heat treatment temperature in the solidifying heat treatment step S02 is 800°C or higher. It is also preferable that the holding time at 800°C or higher is 4 hours or more. By performing the solidifying heat treatment under these conditions, it is possible to suppress the segregation of various elements and achieve a homogeneous state without having to apply a high processing rate in the subsequent hot rolling process.

[0044] (Hot working process S03) Next, hot working is performed to form a dynamic recrystallized structure. In this hot working process S03, the objective is to obtain a dynamic recrystallized structure from the cast structure, so hot working with a total processing rate of 30% or less is necessary to create the structure. Furthermore, by setting the processing temperature to 700°C or higher, a structure in the preliminary stage before creating the desired structure can be formed. The total processing rate is more preferably 25% or less, and more preferably 20% or less. Furthermore, the processing temperature is more preferably 720°C or higher, and more preferably 740°C or higher. The processing method is not particularly limited, but if the final shape is a plate or strip, rolling is preferred. For wires and rods, extrusion or groove rolling is preferred, and for bulk shapes, forging or pressing is preferred. By combining this with subsequent rolling and heat treatment processes, the desired structure can be obtained.

[0045] (Surface Machining Process S04) Surface machining is performed to remove the oxide film formed on the surface in the hot working process S03 described above. The surface machining allowance is preferably in the range of 0.5 mm to 3.0 mm.

[0046] (Plastic working process S05) Next, plastic working is performed with a processing rate of 90% or more. By applying plastic working with a processing rate of 90% or more to the recrystallized structure obtained in the hot working process S03, a crystal structure oriented in the cube orientation can be obtained during the subsequent recrystallization process. By obtaining a crystal structure having the cube orientation, a crystal structure with the above-mentioned crystal orientation can be formed by subsequent heat treatment and processing. The processing method in the plastic working process S05 is not particularly limited, but rolling is used when the final form is a plate or strip. Other methods such as forging, pressing, and groove rolling may also be used. The processing temperature is also not particularly limited, but it is preferable to set it within the range of -200°C to 400°C, which is either cold or warm.

[0047] (First heat treatment step S06) Next, heat treatment is performed to create a crystalline structure. Here, it is preferable to perform the heat treatment in a non-oxidizing or reducing atmosphere. It is also preferable that the heat treatment temperature be in the range of 500°C to 900°C. Furthermore, it is preferable that the holding time at the heat treatment temperature be in the range of 1 minute to 60 minutes. It is also preferable to cool the material by adding water after the heat treatment. By performing this first heat treatment step S06, the cube orientation is formed. And by forming the cube orientation, it becomes possible to form the crystalline structure of the copper material of this embodiment in a later step.

[0048] (Intermediate rolling process S07) Next, rolling is applied with a rolling ratio of 30% or less. By applying low rolling with a rolling ratio of 30% or less to the microstructure that has formed the cube orientation as described above, a small amount of new recrystallization nuclei are formed in the subsequent heat treatment, and a desirable crystal orientation is grown.

[0049] (Second heat treatment step S08) Next, heat treatment is performed to form recrystallization nuclei and grow a preferred crystal orientation. Here, it is preferable to carry out the heat treatment in a non-oxidizing or reducing atmosphere. It is also preferable that the heat treatment temperature be in the range of 500°C to 900°C. Furthermore, it is preferable that the holding time at the heat treatment temperature be in the range of 1 minute to 60 minutes. It is also preferable to cool the product by adding water after the heat treatment. By performing this second heat treatment step S08, it is possible to preferentially grow crystals in a preferred crystal orientation and form a preferred structure.

[0050] (Temper rolling process S09) Then, rolling is applied to a predetermined rolling ratio in order to adjust the strength of the material. In order not to significantly damage the crystalline structure formed in the previous process, it is preferable that the rolling ratio in the temper rolling process S09 be 20% or less.

[0051] Through the processes described above, the copper material of this embodiment is produced.

[0052] In this embodiment, the copper material has the above-described configuration, and the Cu content is in the range of 99.9 mass% to 99.999 mass%, and the conductivity is 90% IACS or higher. Therefore, it has particularly excellent conductivity and heat dissipation, making it especially suitable as a material for components in electronic and electrical equipment used for high-current applications. Furthermore, since it contains one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, and Sb in a total amount of 2 mass ppm to 20 mass ppm, the movement of crystal interfaces is inhibited by these Group A elements. Even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing grain coarsening when joining the ceramic substrate 11 and the copper material can be stably exhibited.

[0053] Furthermore, in the plane perpendicular to the thickness direction (rolling plane), the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> are set as S(110), S(311), S(331), S(210), S(321), and S(211), respectively, satisfying equation (1): S(110) + S(311) + S(331) + S(210) + S(211) > S(321). As a result, grain boundary movement can be stably suppressed, and grain growth under high-temperature conditions such as heat treatment during joining can be sufficiently suppressed.

[0054] In the copper material of this embodiment, if the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> on a plane perpendicular to the thickness direction (rolled surface) are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and the following relationship is satisfied, then grain boundary movement can be further stably suppressed, and grain growth under high-temperature conditions such as heat treatment during joining can be further suppressed. S(110) < 0.2 S(311) < 0.3 S(331) < 0.2 S(210) < 0.3 S(321) > 0.1 S(211) < 0.3

[0055] In the copper material of this embodiment, the average grain size D is measured on a surface perpendicular to the thickness direction (rolled surface). ａｖｅ For example, the crystal grain size is 2×D ａｖｅ When the area ratio of the above-mentioned crystal grains is 10% or less, there are not many coarse crystal grains, resulting in a uniform crystal structure and excellent various properties.

[0056] In the copper material of this embodiment, when one or more B group elements selected from Ca, Sr, and Ba are included in a total amount of 10 mass ppm to 200 mass ppm, a compound containing at least one B group element and Cu is formed, and the pinning effect of this compound makes it possible to further reliably suppress grain growth under high-temperature conditions such as heat treatment during bonding.

[0057] In this embodiment, the insulating substrate 10 has a copper plate made of the copper material of this embodiment bonded to at least one surface of the ceramic substrate 11 to form a circuit layer 12 and a metal layer 13. As a result, crystal grain growth under high-temperature conditions such as heat treatment during bonding is suppressed, resulting in a uniform crystal structure and stable properties, making it suitable for use as a component of the electronic device 1.

[0058] In the insulating substrate 10 of this embodiment, when the ceramic substrate 11 is made of silicon nitride, alumina, or aluminum nitride, the insulating properties of the ceramic substrate 11 are excellent, and it can be used well as a component of the electronic device 1.

[0059] In the insulating substrate 10 of this embodiment, if a plating layer is formed on either the side of the circuit layer 12 opposite to the ceramic substrate 11, or on either or both of the side of the metal layer 13 opposite to the ceramic substrate 11, the semiconductor element 3 can be well bonded to the circuit layer 12 and the heat sink 51 can be well bonded to the metal layer 13, thereby enabling the construction of the electronic device 1 shown in Figure 1.

[0060] Although an embodiment of the present invention, a copper material, has been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention. For example, although an example of a method for manufacturing a copper material was described in the above embodiment, the method for manufacturing a copper material is not limited to that described in the embodiment, and an existing manufacturing method may be appropriately selected and used for manufacturing.

[0061] The results of the verification experiments conducted to confirm the effects of the present invention are described below.

[0062] Copper raw material A, consisting of pure copper with a purity of 99.999 to 99.9999 mass% or higher, and copper raw material B, consisting of pure copper with a purity of 99.99 to 99.999 mass%, were prepared by a melting and refining method to reduce the P concentration to 0.001 mass ppm or less. These copper raw materials were then charged into high-purity graphite crucibles and high-frequency melted in an atmospheric furnace with an Ar gas atmosphere. The resulting molten copper was then mixed with various 1 mass% master alloys made using 6N (purity of 99.9999 mass% or higher) high-purity copper and 2N (purity of 99 mass% or higher) pure metals to adjust the composition. The mixture was then poured into an insulating material (isowool) mold to produce ingot A using copper raw material A and ingot B using copper raw material B. The size of the ingot was approximately 100 mm thick x 100 mm wide x 150-200 mm long.

[0063] Tables 1 and 2 show the results of measuring the copper content and various elemental content of the obtained ingots A and B. Samples were taken from the obtained ingots and measured using a glow discharge mass spectrometer (GD-MS). Measurements were performed at two locations: the center of the sample and the widthwise edge. The higher concentration was used as the sample's content.

[0064] The ingots A and B obtained as described above were subjected to soaking heat treatment in an Ar gas atmosphere under the conditions shown in Tables 3 and 4. Next, hot rolling was performed under the conditions shown in Tables 3 and 4. After that, surface milling was performed to remove the oxide film. Next, rolling (plastic deformation) was performed under the conditions shown in Tables 3 and 4. After that, a first heat treatment was performed in an Ar gas atmosphere under the conditions shown in Tables 3 and 4. Next, intermediate rolling was performed under the conditions shown in Tables 3 and 4. After that, a second heat treatment was performed in an Ar gas atmosphere under the conditions shown in Tables 3 and 4. Finally, temper rolling was performed under the conditions shown in Tables 3 and 4 to produce strips of the thickness shown in Tables 3 and 4 (strips for characteristic evaluation).

[0065] The following items were evaluated. The evaluation results are shown in Tables 5 and 6.

[0066] (EBSD Measurement Method) Samples taken from the characterization strip material using ingot B were mechanically polished using waterproof abrasive paper and diamond abrasive grains, followed by finish polishing with colloidal silica solution. Then, using an EBSD measuring device (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity super, APEX EBSD Ver.2.9) and analysis software (EDAX / AMETEK OIM Analysis ver.8.6), the orientation difference of each crystal grain was analyzed in steps of 0.1 μm, excluding measurement points with a CI value of 0.1 or less, at an electron beam acceleration voltage of 15 kV and a measurement area of ​​10,000 μm² or more. The orientation difference between adjacent measurement points was defined as crystal grain boundaries where the orientation difference between them was 15° or more.

[0067] (Area ratio of crystal orientation) For samples taken from the characterization strip material using ingot B, the surface perpendicular to the plate thickness direction was used as the observation surface. After mechanical polishing with waterproof abrasive paper and diamond abrasive grains, finish polishing was performed with colloidal silica solution. Then, using an EBSD measuring device (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity super, APEX EBSD Ver.2.9) and analysis software (EDAX / AMETEK OIM Analysis ver.8.6), the electron beam was accelerated at 15kV and 1 × 10⁻⁶ ６For measurement areas of μm² or larger, the orientation difference of each crystal grain was analyzed in steps of 1.0 μm, excluding measurement points with a CI value of 0.1 or less. Grain boundaries were defined as measurement points where the orientation difference between adjacent measurement points was 15° or more. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), crystals oriented within 10° of each crystal orientation were measured as that crystal orientation, and the area ratio in the field of view was obtained. Furthermore, those that satisfied equation (1) were designated as "G," and those that did not were designated as "NG."

[0068] (Average grain size D ａｖｅ and 2×D ａｖｅ (Measurement of the area ratio of the above crystal grains) For samples taken from the characteristic evaluation strip material using ingot B, the surface perpendicular to the plate thickness direction was used as the observation surface. After mechanical polishing with waterproof abrasive paper and diamond abrasive grains, finish polishing was performed with colloidal silica solution. Then, using an EBSD measuring device (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity super, APEX EBSD Ver.2.9) and analysis software (EDAX / AMETEK OIM Analysis ver.8.6), the electron beam was accelerated at 15kV and 1 × 10⁻¹⁶ ６ For measurement areas of μm² or larger, the orientation difference of each crystal grain was analyzed in steps of 1.0 μm, excluding measurement points with a CI value of 0.1 or less. Crystal grain boundaries were defined as measurement points where the orientation difference between adjacent measurement points was 15° or more. The grain size distribution and average grain size were obtained using the AreaFraction method with analysis software (EDAX / AMETEK OIM Analysis ver. 8.6). Twin grain boundaries were excluded from the calculations.

[0069] (Electrical conductivity) A 10 mm wide x 150 mm long test specimen was taken from the characteristic evaluation strip made from ingot B, and its electrical resistance was determined by the four-terminal method. The dimensions of the test specimen were measured using a micrometer, and its volume was calculated. The electrical conductivity was then calculated from the measured electrical resistance value and volume. The test specimen was taken so that its longitudinal direction was parallel to the rolling direction of the characteristic evaluation strip.

[0070] (Bonding Test) 40 mm x 40 mm copper plates were cut from the characteristic evaluation strip material using ingot A and the characteristic evaluation strip material using ingot B. Ceramic plate (Material: Si ３ N ４ A paste-like activated silver brazing material (TB-608T, manufactured by Tokyo Blaze) was applied to both sides of a copper plate measuring 50 mm x 50 mm x 0.32 mm thick. A ceramic plate was sandwiched between the two copper plates, and heat treatment was performed under a pressure of 0.59 MPa. The heat treatment was carried out under the following conditions: The stacked copper plate and ceramic plate were placed in an 850°C furnace, and after confirming that the material temperature reached 850°C with a thermocouple, it was held for 60 minutes, and after heating was completed, it was furnace-cooled (cooled in the furnace) until it reached room temperature. After the temperature had cooled to room temperature, the crystalline structure was measured on the surface (rolled surface) perpendicular to the thickness direction of the copper plate of ingot B.

[0071] The surface perpendicular to the thickness direction (rolled surface) was used as the observation surface. After mechanical polishing using waterproof abrasive paper and diamond abrasive grains, finish polishing was performed using colloidal silica solution. Then, using an EBSD measuring device (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity super, APEX EBSD Ver.2.9) and analysis software (EDAX / AMETEK OIM Analysis ver.8.6), the electron beam was accelerated at 15kV and 1 × 10⁻⁶ ７ For measurement areas of μm² or larger, the orientation difference of each crystal grain was analyzed in steps of 2.0 μm intervals, excluding measurement points with a CI value of 0.1 or less. Grain boundaries were defined as measurement points where the orientation difference between adjacent measurement points was 15° or more. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), the average crystal grain size and maximum crystal grain size, excluding twin grain boundaries, were obtained by the Area Fraction method.

[0072] The results of the crystal coarsening of the characterization strip material using ingot A and the characterization strip material using ingot B were evaluated as follows: "C" when there was a difference of 1000 μm or more in the maximum crystal grain size between A and B; "B" when there was no difference of 1000 μm or more in the maximum crystal grain size between A and B, and the average crystal grain size of either A or B was 1000 μm or more; and "A" when there was no difference of 1000 μm or more in the maximum crystal grain size between A and B, and the average crystal grain size of both A and B was less than 1000 μm.

[0073] (Heat Treatment Test) A sample taken from a strip material used for characterization using ingot B was placed in a furnace at a temperature of 800°C and held for 1 hour, after which the sample was cooled by air cooling. The obtained sample was mechanically polished using waterproof abrasive paper and diamond abrasive grains, with the surface perpendicular to the plate thickness direction designated as the observation surface, and then finished polished with colloidal silica solution. Then, an EBSD measurement device (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity Super, APEX EBSD Ver. 2.9) and analysis software (EDAX / AMETEK OIM Analysis Ver. 8.6) were used to measure the electron beam at an acceleration voltage of 15kV and 1 × 10⁻⁶ ７ μm ２ The above measurement area was analyzed for the orientation difference of each crystal grain, excluding measurement points with a CI value of 0.1 or less at measurement intervals of 2.0 μm. Grain boundaries were defined as measurement points where the orientation difference between adjacent measurement points was 15° or more. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), the average crystal grain size calculated excluding twin grain boundaries using the Area Fraction method was evaluated as "NG" if it was greater than 800 μm, and as "G" if the average crystal grain size was 800 μm or less.

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080] In Comparative Examples 1-5, the area ratio of crystal orientations on the plane perpendicular to the thickness direction (rolled surface) did not satisfy equation (1). As a result of the joining test, the difference in maximum grain size between the strip material for characterization using ingot A and the strip material for characterization using ingot B was large, exceeding 1000 μm, and the effect of suppressing grain coarsening could not be stably exhibited. Furthermore, in Comparative Example 6, the total content of group A elements was low at 1.4 mass ppm, and when the strip material for characterization using ingot B was heat-treated at 800°C for 1 hour, the average grain size became larger than 800 μm, and grain coarsening could not be sufficiently and stably suppressed.

[0081] In contrast, in the present invention example 1-12, the area ratio of crystal orientations on the plane perpendicular to the thickness direction (rolled surface) satisfies equation (1), and as a result of the joining test, the difference in maximum crystal grain size between the strip material for character evaluation using ingot A and the strip material for character evaluation using ingot B was less than 1000 μm, demonstrating a stable effect of suppressing crystal grain coarsening. Furthermore, in the present invention example 1-12, the total content of group A elements was in the range of 2 mass ppm to 20 mass ppm, and when the strip material for character evaluation using ingot B was heat-treated at 800°C for 1 hour, the average crystal grain size became 800 μm or less, demonstrating sufficient suppression of crystal grain coarsening.

[0082] From the above, it has been confirmed that, according to the present invention, even when the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, it is possible to stably exhibit the effect of suppressing grain coarsening when bonding a ceramic substrate and a copper material, and to provide a copper material with stable properties, as well as an insulating substrate using this copper material.

Claims

1. The Cu content is within the range of 99.9 mass% or more and 99.999 mass%, and it contains one or more Group A elements selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, Cr, Si, Ti, Zr, Hf, Mn, Fe, Ag, Zn, In, Ga, Ge, Sb in a total amount of 2 mass ppm or more and 20 mass ppm or less, and the conductivity is 95% IACS or higher. A copper material characterized by satisfying the following equation (1), where the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> in a plane perpendicular to the thickness direction are S(110), S(311), S(331), S(210), S(321), and S(211), respectively: (1) Equation: S(110) + S(311) + S(331) + S(210) + S(211) > S(321) 2. The copper material according to claim 1, characterized in that, in a plane perpendicular to the thickness direction, the area ratios of crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, satisfy the following relationships: S(110) < 0.2, S(311) < 0.3, S(331) < 0.2, S(210) < 0.3, S(321) > 0.1, S(211) < 0.3 3. In a plane perpendicular to the thickness direction, the average grain size D ａｖｅ For example, the crystal grain size is 2×D ａｖｅ The copper material according to claim 1, characterized in that the area ratio of the above crystal grains is 10% or less.

4. The copper material according to claim 1, characterized in that it contains one or more B group elements selected from Ca, Sr, and Ba in a total amount of 10 mass ppm or more and 200 mass ppm or less.

5. An insulating substrate comprising a ceramic substrate and a copper plate bonded to at least one surface of the ceramic substrate, wherein the copper plate is made of the copper material described in any one of claims 1 to 4.

6. The insulating substrate according to claim 5, characterized in that the ceramic substrate is silicon nitride, alumina, or aluminum nitride.

7. The insulating substrate according to claim 5, characterized in that a plating layer is formed on the side of the copper plate opposite to the ceramic substrate.

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