Copper plate and insulating substrate

Abstract

To provide a copper material having stable characteristics and capable of stably suppressing the coarsening of crystal grains when joining a ceramic substrate and a copper material, even when the amount of impurities dissolved in the copper matrix fluctuates, and an insulating substrate using this copper material. [Solution] The Cu content is within the range of 99.9 mass% or more and 99.999 mass% or less, and one or more A group 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 of 2 massppm to 20 massppm, the electrical conductivity is 95% IACS or more, and in the plane perpendicular to the thickness direction, the area ratios of each crystal orientation S(110), S(311), S(331), S(210), S(321), and S(211) satisfy S(110) + S(311) + S(331) + S(210) + S(211) > S(321).

Description

[Technical Field]

[0001] The present invention is suitable for electric and electronic components such as heat sinks and thick copper circuits. Copper plate It is used for insulating substrates, particularly for power semiconductors. Copper plate , and this Copper plate The present invention relates to an insulating substrate using the above. [Background technology]

[0002] Conventionally, copper materials with high electrical conductivity have been used for electrical and electronic components such as heat sinks and thick copper circuits. Recently, resistance heating has become a problem due to the increase in the amount of current used in electrical and electronic equipment components. In electronic devices such as semiconductor devices, for example, insulating substrates in which a copper material is bonded to a ceramic substrate and the above-mentioned heat sink or thick copper circuit is formed are used.

[0003] When joining a ceramic substrate and copper material, pressure processing is performed in a high-temperature atmosphere, which can cause the crystal grain size of the copper material to become coarse or grow unevenly, resulting in poor bonding, poor appearance, and problems during the inspection process. To solve this problem, copper materials are required to have small changes in crystal grain size and to have uniform size even after heat treatment.

[0004] Therefore, for example, Patent Documents 1 and 2 propose techniques for suppressing crystal growth in copper materials. Patent Document 1 describes that by including 0.0006 to 0.0015 wt % of S, it is possible to adjust the crystal grain size to a constant size even when heat treatment is performed at a temperature equal to or higher than the recrystallization temperature. Furthermore, Patent Document 2 states that by including Ca and specifying the ratio of the Ca content to the total content of O, S, Se, and Te, it is possible to suppress coarsening of crystal grains even when heat-treated at 800°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 06-002058 [Patent Document 2] International Publication No. 2020 / 203071 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, Patent Documents 1 and 2 are configured to suppress coarsening of crystal grains by specifying the composition, but variations in the amount of impurities dissolved in the copper matrix (copper purity) can cause significant changes in characteristics, making it impossible to stably produce copper materials, and there is a risk of a significant drop in productivity.

[0007] This invention has been made in view of the above-mentioned circumstances, and aims to provide a method for manufacturing a ceramic substrate even when the amount of impurities dissolved in the copper matrix (purity of copper) fluctuates. Copper plate It is possible to stably suppress the coarsening of crystal grains when joining, and the properties are stable. Copper plate ,this Copper plate The present invention aims to provide an insulating substrate using the above. [Means for solving the problem]

[0008] In order to solve this problem, the inventors conducted extensive research and discovered that by controlling the structure of the copper material and the content of trace elements, it is possible to stably suppress the coarsening of crystal grains when joining a ceramic substrate and a copper material, even if the amount of impurities dissolved in the copper matrix (copper purity) varies, and it is also possible to provide a copper material with stable properties.

[0009] The present invention has been made based on the above findings, and the present invention provides the following: Copper plateThe Cu content is within the range of 99.9 mass% or more and 99.999 mass% or less, and one or more A group 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 within the range of 2 massppm or more and 20 massppm or less in total, the electrical conductivity is 95% IACS or more, and the crystal orientation in the plane perpendicular to the thickness direction is <110> , <311> , <331> , <210> , <321> , <211> The area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and are characterized by satisfying the following formula (1). (1) Formula: S(110)+S(311)+S(331)+S(210)+S(211)>S(321)

[0010] Aspect 1 of the present invention Copper plate According to the standard, the Cu content is set to be within the range of 99.9 mass% or more and 99.999 mass% or less, and the conductivity is set to be 95% IACS or more, so the material has particularly excellent conductivity and heat dissipation properties and is particularly suitable as a material for parts of electronic and electrical equipment for large current applications. Furthermore, the material contains one or more A group 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 ranging from 2 massppm to 20 massppm, and the area ratio of each crystal orientation in the plane perpendicular to the thickness direction satisfies the above formula (1). Therefore, the movement of the crystal grain boundary can be stably suppressed, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the material can be used in combination with a ceramic substrate. Copper plate This can stably suppress the coarsening of crystal grains when bonding, and also stabilizes various properties.

[0011] Aspect 2 of the present invention Copper plate is aspect 1 Copper plateIn the plane perpendicular to the thickness direction, the crystal orientation <110> , <311> , <331> , <210> , <321> , <211> The area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and are characterized by satisfying 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 Aspect 2 of the present invention Copper plate According to the above, since the area ratios of each crystal orientation in the plane perpendicular to the thickness direction have the above-mentioned relationship, the movement of the crystal grain boundaries can be more stably suppressed, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the ceramic substrate and Copper plate This makes it possible to more stably suppress the coarsening of crystal grains when bonding, and also stabilizes various properties.

[0012] Aspect 3 of the present invention Copper plate is the same as in Aspect 1 or Aspect 2. Copper plate In the plane perpendicular to the thickness direction, the average grain size D ave Assuming that the grain size is 2 × D ave The area ratio of the above crystal grains is 10% or less. Aspect 3 of the present invention Copper plate According to the average grain size D ave Assuming that the grain size is 2 × D ave Since the area ratio of the above crystal grains is set to 10% or less, there are not many coarse crystal grains, resulting in a uniform crystal structure and excellent properties.

[0013] Aspect 4 of the present invention Copper plate is any one of aspects 1 to 3 Copper plate The present invention is characterized in that it contains one or more B group elements selected from Ca, Sr, and Ba in a total amount within the range of 10 massppm to 200 massppm. Aspect 4 of the present invention Copper plate According to the method described above, one or more B group elements selected from Ca, Sr, and Ba are contained in a total amount within the range of 10 massppm to 200 massppm, so that 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 more reliably suppress the growth of crystal grains during heat treatment.

[0014] The insulating substrate of the fifth aspect of the present invention is an insulating substrate including a ceramic substrate and a copper plate bonded to at least one surface of the ceramic substrate, and the copper plate is an insulating substrate according to any one of the first to fourth aspects. Copper plate It is characterized by being composed of According to the insulating substrate of the fifth aspect of the present invention, the copper plate bonded to at least one surface of the ceramic substrate is any one of the insulating substrates of the first to fourth aspects. Copper plate Since the material is made of the above, the growth of crystal grains during bonding is suppressed, the material has a uniform crystal structure, and can be used stably.

[0015] An insulating substrate according to a sixth aspect of the present invention is characterized in that, in the insulating substrate according to the fifth aspect of the present invention, the ceramic substrate is made of silicon nitride, alumina, or aluminum nitride. According to the insulating substrate of the sixth aspect of the present invention, the ceramic substrate is made of any of silicon nitride, alumina, and aluminum nitride, and therefore the ceramic substrate has excellent insulating properties and can be used stably.

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

[0017] According to the present invention, even if the amount of impurities dissolved in the copper matrix (purity of copper) fluctuates, the ceramic substrate and Copper plate It is possible to stably suppress the coarsening of crystal grains when joining, and the properties are stable. Copper plate ,this Copper plate It is possible to provide an insulating substrate using the above. [Brief explanation of the drawings]

[0018]

Figure 1

Figure 2

[0019] Hereinafter, a copper material and an insulating substrate according to one embodiment of the present invention will be described with reference to the accompanying drawings. The copper material of this embodiment is used as a material for electric and electronic components such as heat sinks and thick copper circuits, and when forming the above-mentioned electric and electronic components, it is bonded to, for example, a ceramic substrate to form an insulating substrate.

[0020] FIG. 1 shows an insulating substrate 10 according to an embodiment of the present invention, and an electronic device 1 using this insulating substrate 10. The electronic device 1 shown in Figure 1 comprises an insulating substrate 10 of this embodiment, an electronic component 3 joined to one side (upper side in Figure 1) of the insulating substrate 10 via a first solder layer 2, and a heat sink 51 joined to the other side (lower side in Figure 1) of the insulating substrate 10 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 comprises 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 with excellent insulating and heat dissipating properties, such as silicon nitride (Si3N4), aluminum nitride (AlN), alumina (Al2O3), etc. In this embodiment, the ceramic substrate 11 is made of silicon nitride (Si3N4), which has particularly excellent heat dissipating properties. The thickness of the ceramic substrate 11 is set, for example, within the range of 0.2 mm to 1.5 mm, and is set to 0.32 mm in this embodiment.

[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) serves as a mounting surface on which electronic components 3 are mounted. It is preferable that a plating layer of, for example, 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 joining a copper plate to the other surface of the ceramic substrate 11. This metal layer 13 has the effect of efficiently transferring heat from the electronic component 3 to the heat sink 51. It is preferable that a plating layer of, for example, Ni or Ag is formed on the surface of the metal layer 13 opposite to the ceramic substrate 11.

[0025] Here, the copper plate that will become the circuit layer 12 and the ceramic substrate 11, and the copper plate that will become the metal layer 13 and the ceramic substrate 11 are bonded by an existing bonding method such as the DBC method or the AMB method. The temperature during bonding is a high temperature condition of, for example, 750° C. or higher, which may cause the crystal grains in the circuit layer 12 and the metal layer 13 to become coarse.

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

[0027] The copper material of this embodiment has a Cu content in the range of 99.9 mass% or more and 99.999 mass% or less, and contains one or more A group 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 in the range of 2 massppm or more and 20 massppm or less. The copper material of this embodiment may contain one or more B group elements selected from Ca, Sr, and Ba in a total amount within the range of 10 massppm to 200 massppm.

[0028] Furthermore, the copper material of this embodiment has a conductivity of 95% IACS or more.

[0029] In the copper material of this embodiment, the crystal orientation is <110> , <311> , <331> , <210> , <321> , <211> The area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and are considered to satisfy the following equation (1). (1) Formula: S(110)+S(311)+S(331)+S(210)+S(211)>S(321)

[0030] In addition, in the copper material of this embodiment, the crystal orientation is <110> , <311> , <331> , <210> , <321> , <211> It is preferable that the area ratios of S(111), S(110), S(311), S(331), S(210), S(321), and S(211) respectively 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

[0031] Furthermore, in the copper material of this embodiment, the average crystal grain size D ave Assuming that the grain size is 2 × D ave The area ratio of the above crystal grains is preferably 10% or less.

[0032] The reasons for specifying the Cu content, the contents of various elements, the crystal orientation, the crystal grain size, and the electrical conductivity of the copper material of this embodiment as described above will be explained below.

[0033] (Cu content) Electrical and electronic components for large current applications require excellent electrical conductivity and heat dissipation to suppress heat generation when current is applied, so it is preferable to use high-purity copper materials that are particularly excellent in electrical conductivity and heat dissipation. On the other hand, if the purity of copper is too high, the crystal grains may easily become coarse under high heat conditions. Therefore, in the copper material of this embodiment, the Cu content is set to a 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, more preferably 99.96 mass% or more, and the upper limit of the Cu content is preferably 99.998 mass% or less, more preferably 99.997 mass% or less.

[0034] (Total content of one or more A group 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) The presence of one or more A group 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 the Cu matrix inhibits the migration of crystal grain boundaries, making it possible to suppress the coarsening of crystal grains during heat treatment. Furthermore, by specifying the content of these A group elements, it is possible to stabilize the properties. If the total content of the A group elements is less than 2 mass ppm, the above-mentioned effects may not be obtained, whereas if the total content of the A group elements is more than 20 mass ppm, the recyclability of the resulting pure copper may not be ensured. Therefore, in the copper material of this embodiment, the total content of one or more A group 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 is specified to be in the range of 2 massppm or more and 20 massppm or less. The lower limit of the total content of the A group elements is preferably 4 massppm or more, more preferably 6 massppm or more, and the upper limit of the total content of the A group elements is preferably 18 massppm or less, more preferably 16 massppm 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 in Cu and form compounds with Cu. Therefore, the inclusion of B-group elements results in the formation of compounds that are stable even at high temperatures. Furthermore, because these compounds contain Cu, there is no risk of a significant decrease in thermal conductivity. Therefore, the addition of B-group elements produces compounds that are stable at high temperatures, suppressing grain boundary migration at high temperatures and further suppressing grain growth. On the other hand, the inclusion of large amounts of B-group elements may adversely affect manufacturability. Therefore, when the copper material of this embodiment contains B group elements, it is preferable that the total content of the B group elements be within the range of 10 massppm to 200 massppm. The lower limit of the total content of the B group elements is more preferably 15 massppm or more, and even more preferably 20 massppm or more, and the upper limit of the total content of the B group elements is more preferably 150 massppm or less, and even more preferably 100 massppm or less.

[0036] (Other unavoidable impurities) Examples of unavoidable impurities other than the above-mentioned elements 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 contained to the extent that they do not affect the characteristics.

[0037] (conductivity) In electrical and electronic equipment components, excellent electrical conductivity is required to suppress heat generation when current is applied. For this reason, the electrical conductivity of the copper material of this embodiment is specified to be 95% IACS or more. The conductivity of the copper material of this embodiment is preferably 98% IACS or more, and more preferably 100% IACS or more.

[0038] (area ratio of crystal orientation in the plane perpendicular to the thickness direction) In the copper material of this embodiment, the crystal orientation in the plane (rolled surface) perpendicular to the plate thickness direction <110> , <311> , <331> , <210> , <321> , <211> The area ratios of these are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and are considered to satisfy the above equation (1). As described above, by specifying the area ratio of the crystal orientation in the plane (rolled surface) perpendicular to the thickness direction of the plate, it is possible to stably suppress the movement of crystal grain boundaries, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing the coarsening of crystal grains when joining a ceramic substrate and a copper material can be stably exerted, and various properties are stabilized.

[0039] In the copper material of this embodiment, the crystal orientation in the plane (rolled surface) perpendicular to the plate thickness direction <110> , <311> , <331> , <210> , <321> , <211> When the area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and the following relationship is satisfied, the movement of the crystal grain boundaries can be more stably suppressed, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing the coarsening of crystal grains when joining a ceramic substrate and a copper material can be more stably exerted, and various properties will be stabilized. 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] (crystal grain size) In the copper material of this embodiment, the average grain size D ave Assuming that the grain size is 2 × D ave When the area ratio of the above crystal grains is 10% or less, there are not many coarse crystal grains, the grain size is relatively uniform, and the properties are stable. In addition, the grain size is 2 × D ave The area ratio of the above crystal grains is more preferably 7% or less, and even more preferably 5% or less. Furthermore, in the copper material of this embodiment, the average crystal grain size D ave 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 producing a copper material according to this embodiment having the above-described configuration will be described with reference to the flow chart shown in FIG.

[0042] (Melting and casting process S01) First, the composition of 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. The various elements can be added as simple elements or master alloys. Raw materials containing the above elements may also be melted together with the copper raw material. Here, each element preferably has a purity of 99.9 mass% or higher, known as 3N, or 99.99 mass% or higher, known as 4N. During melting, in order to reduce the hydrogen concentration, it is preferable to carry out atmospheric melting in an inert gas atmosphere (for example, Ar gas) with a low vapor pressure of H2O, and to keep the holding time during melting to a minimum. The molten copper with the adjusted composition is then poured into a mold to produce an ingot. When mass production is taken into consideration, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0043] (Soaking heat treatment process S02) The resulting ingot is subjected to a soaking heat treatment in order to homogenize segregated components within the material. The heat treatment temperature in the soaking heat treatment step S02 is preferably 800°C or higher. In addition, the holding time at 800°C or higher is preferably 4 hours or longer. By performing the soaking heat treatment under such conditions, it is possible to suppress the segregation of various elements and achieve a homogeneous state without imparting a high processing rate in the subsequent hot rolling process.

[0044] (Hot processing process S03) Next, hot working is performed to form a dynamically recrystallized structure. In this hot working step S03, the purpose is to obtain a dynamically recrystallized structure from the cast structure, so in order to create the structure, hot working with a total working ratio of 30% or less is required. Furthermore, by setting the working temperature at 700°C or higher, it is possible to form a structure that is a precursor to creating the desired structure. The total processing rate is more preferably 25% or less, and even more preferably 20% or less. The processing temperature is more preferably 720°C or more, and even more preferably 740°C or more. Although the processing method is not particularly limited, it is preferable to use rolling when the final shape is a plate or strip. It is preferable to use extrusion or groove rolling when the final shape is a wire or rod, and forging or pressing when the final shape is a bulk shape. By combining this with subsequent rolling and heat treatment steps, the desired structure can be obtained.

[0045] (Facing process S04) In the above-mentioned hot working step S03, facing is performed to remove the oxide film formed on the surface. The facing allowance is preferably within a range of 0.5 mm to 3.0 mm.

[0046] (Plastic working process S05) Next, plastic working is performed at a working rate of 90% or more. By performing plastic working at a working rate of 90% or more on the recrystallized structure obtained in the hot working step S03, a crystal structure oriented in the Cube orientation can be obtained during the subsequent recrystallization process. Here, by obtaining a crystal structure having the Cube orientation, it is possible to form a crystal structure having the above-mentioned crystal orientation by subsequent heat treatment and processing. The processing method in the plastic processing step S05 is not particularly limited, but when the final form is a plate or strip, rolling is used. Alternatively, forging, pressing, or groove rolling may be used. The processing temperature is not particularly limited, but is preferably within the range of -200°C to 400°C, which corresponds to cold or warm processing.

[0047] (First heat treatment step S06) Next, heat treatment is performed to create a crystalline structure. The heat treatment is preferably performed in a non-oxidizing or reducing atmosphere. The heat treatment temperature is preferably in the range of 500°C to 900°C. The holding time at the heat treatment temperature is preferably in the range of 1 minute to 60 minutes. After the heat treatment, the material is preferably cooled in water. By performing this first heat treatment step S06, a Cube orientation is formed. By forming the Cube orientation, it becomes possible to form the crystal structure of the copper material of this embodiment in a later step.

[0048] (Intermediate rolling process S07) Next, the material is rolled to a reduction ratio of 30% or less. By applying low rolling to the structure that has formed the Cube orientation as described above, a small amount of new recrystallization nuclei are formed during subsequent heat treatment, and the preferred crystal orientation is grown.

[0049] (Second heat treatment step S08) Next, heat treatment is performed to form recrystallization nuclei and grow the preferred crystal orientation. The heat treatment is preferably performed in a non-oxidizing or reducing atmosphere. The heat treatment temperature is preferably in the range of 500°C to 900°C. The holding time at the heat treatment temperature is preferably in the range of 1 minute to 60 minutes. After the heat treatment, the material is preferably cooled in water. By carrying out this second heat treatment step S08, crystals can be grown preferentially in a preferred crystal orientation, and a preferred structure can be formed.

[0050] (Temp rolling process S09) Then, the material is rolled at a predetermined rolling reduction ratio to adjust the strength of the material. Note that the rolling reduction ratio in the temper rolling step S09 is preferably 20% or less to avoid excessive destruction of the crystalline structure formed in the previous step.

[0051] The copper material of this embodiment is produced through the above-described steps.

[0052] The copper material of this embodiment configured as described above has a Cu content within the range of 99.9 mass% to 99.999 mass%, and an electrical conductivity of 90% IACS or higher. Therefore, the copper material has particularly excellent electrical conductivity and heat dissipation properties, and is particularly suitable as a material for components of electronic and electrical devices for large current applications. Furthermore, since the material contains one or more A group 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 within the range of 2 massppm to 20 massppm, these A group elements inhibit the movement of the crystal interface, and even if the amount of impurities dissolved in the copper matrix (copper purity) fluctuates, the effect of suppressing the coarsening of crystal grains when joining the ceramic substrate 11 and the copper material can be stably exerted.

[0053] Furthermore, in the plane (rolled surface) perpendicular to the thickness direction, the crystal orientation <110> , <311> , <331> , <210> , <321> , <211> The area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and are considered to satisfy equation (1): S(110) + S(311) + S(331) + S(210) + S(211)>S(321). This allows stable suppression of grain boundary movement and sufficient suppression of grain growth under high temperature conditions such as heat treatment during joining.

[0054] In the copper material of this embodiment, the crystal orientation in the plane (rolled surface) perpendicular to the plate thickness direction <110> , <311> , <331> , <210> , <321> , <211> When the area ratios of the above are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and the following relationship is satisfied, the movement of the grain boundaries can be more stably suppressed, and the 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 ave Assuming that the grain size is 2 × D ave When the area ratio of the above crystal grains is 10% or less, there are not many coarse crystal grains, resulting in a uniform crystal structure and excellent properties.

[0056] In the copper material of this embodiment, when one or more B group elements selected from Ca, Sr, and Ba are contained in a total amount within the range of 10 massppm to 200 massppm, 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 more reliably suppress grain growth under high temperature conditions such as heat treatment during joining.

[0057] The insulating substrate 10 of this embodiment is formed by bonding a copper plate made of the copper material of this embodiment to at least one surface of the ceramic substrate 11 to form the circuit layer 12 and the metal layer 13. This suppresses grain growth under high temperature conditions such as heat treatment during bonding, and has a uniform crystalline structure and stable characteristics, 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 ceramic substrate 11 has excellent insulating properties and can be suitably used as a component of the electronic device 1.

[0059] In the insulating substrate 10 of this embodiment, when a plating layer is formed on one or both of the surface of the circuit layer 12 opposite the ceramic substrate 11 and the surface of the metal layer 13 opposite 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, and the electronic device 1 shown in Figure 1 can be well constructed.

[0060] Although the copper material according to the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical concept of the invention. For example, in the above embodiment, an example of a method for manufacturing a copper material is described, but 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 for manufacturing. [Example]

[0061] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

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

[0063] The copper content and the contents of various elements in the resulting ingots A and B were measured, and the results are shown in Tables 1 and 2. Measurement samples were taken from the resulting ingots and measured using a glow discharge mass spectrometer (GD-MS). Measurements were taken at two locations, the center and the end in the width direction of the sample, and the content of the sample with the higher content was recorded.

[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 carried out under the conditions shown in Tables 3 and 4. After that, facing was carried out to remove the oxide film. Next, rolling (plastic working) was carried out under the conditions shown in Tables 3 and 4. Thereafter, a first heat treatment was carried out under the conditions shown in Tables 3 and 4 in an Ar gas atmosphere. Next, intermediate rolling was carried out under the conditions shown in Tables 3 and 4. Thereafter, a second heat treatment was carried out under the conditions shown in Tables 3 and 4 in an Ar gas atmosphere. Finally, temper rolling was carried out under the conditions shown in Tables 3 and 4 to produce strips (strips for property evaluation) having thicknesses shown in Tables 3 and 4.

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

[0066] (EBSD measurement method) Samples taken from the strip material used for property evaluation (ingot B) were mechanically polished using waterproof polishing paper and diamond abrasives, followed by a final polish using colloidal silica solution. Using EBSD measurement equipment (Hitachi High-Tech SU7000, EDAX / AMETEK Velocity Super, APEX EBSD Ver. 2.9) and analysis software (EDAX / AMETEK OIM Analysis Ver. 8.6), the misorientation of each grain was analyzed at an electron beam acceleration voltage of 15 kV over a measurement area of ​​10,000 μm or more, with a measurement interval of 0.1 μm, excluding measurement points with a CI value of 0.1 or less. Measurement points with a misorientation of 15° or more between adjacent measurement points were defined as grain boundaries.

[0067] (area ratio of crystal orientation) The surface perpendicular to the thickness direction of the sample taken from the strip material for property evaluation using ingot B was used as the observation surface, and after mechanical polishing using waterproof polishing paper and diamond abrasive grains, it was final polished using colloidal silica solution. Then, using 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), the electron beam acceleration voltage was 15 kV, and the 1 × 10 6 The misorientation of each grain was analyzed for measurement areas of ≥ μm2, excluding measurement points with a CI value of ≤ 0.1 at 1.0 μm measurement intervals. Measurement points where the misorientation between adjacent measurement points was ≥ 15° were defined as grain boundaries. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), the crystal orientations oriented within 10° from each crystal orientation were measured as that crystal orientation, and the area ratio in the field of view was obtained.

[0068] (Average grain size D ave and 2×D ave (Measurement of the area ratio of the above crystal grains) The surface perpendicular to the thickness direction of the sample taken from the strip material for property evaluation using ingot B was used as the observation surface, and after mechanical polishing using waterproof polishing paper and diamond abrasive grains, it was final polished using colloidal silica solution. Then, using 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), the electron beam acceleration voltage was 15 kV, and the 1 × 10 6 The misorientation of each grain was analyzed for measurement areas of ≥ μm2, excluding measurement points with a CI value of ≤ 0.1 at 1.0 μm measurement intervals. Measurement points where the misorientation between adjacent measurement points was ≥ 15° were defined as grain boundaries. The grain size distribution and average grain size were obtained by the Area Fraction method using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), excluding twin grain boundaries.

[0069] (conductivity) Test pieces measuring 10 mm wide and 150 mm long were taken from the strip material for property evaluation using ingot B, and the electrical resistance was measured using the four-terminal method. The dimensions of the test pieces were also measured using a micrometer, and the volume of the test pieces was calculated. The electrical conductivity was then calculated from the measured electrical resistance value and volume. The test pieces were taken so that their longitudinal direction was parallel to the rolling direction of the strip material for property evaluation.

[0070] (Bonding test) Copper plates of 40 mm x 40 mm were cut out from the strip material for property evaluation made from ingot A and the strip material for property evaluation made from ingot B, respectively. A ceramic plate (material: Si3N4, 50mm x 50mm x 0.32mm thick) was coated on both sides with a paste of activated silver brazing filler metal (TB-608T manufactured by Tokyo Blaze). The ceramic plate was sandwiched between the two copper plates described above and heat-treated under a pressure of 0.59MPa. The heat treatment was carried out under the following conditions: The laminated copper and ceramic plates were placed in a furnace at 850°C, and after confirming with a thermocouple that the material temperature had reached 850°C, they were held there for 60 minutes, and after heating was completed, they were cooled to room temperature (cooled inside the furnace). After the temperature was lowered to room temperature, the crystal structure of the copper plate of ingot B was measured on a surface (rolled surface) perpendicular to the thickness direction of the copper plate.

[0071] The surface perpendicular to the thickness direction (rolled surface) was used as the observation surface, and after mechanical polishing using waterproof polishing paper and diamond abrasive grains, final polishing was performed using colloidal silica solution. Then, using 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), the electron beam acceleration voltage was 15 kV, and the 1 × 10 7 The misorientation of each grain was analyzed for measurement areas of ≥ μm2, excluding measurement points with a CI value of ≤ 0.1 at measurement intervals of 2.0 μm. Measurement points where the misorientation between adjacent measurement points was ≥ 15° were defined as grain boundaries. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), the average grain size and maximum grain size were calculated by the area fraction method, excluding twin grain boundaries.

[0072] The results of the crystal coarsening of the strip material for property evaluation made from ingot A and the strip material for property evaluation made from ingot B were evaluated as follows: if there was a difference of 1000 μm or more in the maximum crystal grain size between A and B, it was marked "X"; if 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, it was marked "△"; and if there was no difference of 1000 μm or more in the maximum crystal grain size between A and B and the average grain size of both A and B was smaller than 1000 μm, it was marked "〇".

[0073] (Heat treatment test) A sample taken from the strip material for property evaluation using ingot B was placed in a furnace with an internal temperature of 800°C, held for 1 hour, and then cooled by air. The obtained sample was mechanically polished using waterproof polishing paper and diamond abrasive grains, with the surface perpendicular to the thickness direction as the observation surface, and then final polishing was performed using colloidal silica solution. The EBSD measurement equipment (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 acceleration voltage of 15 kV and 1 × 10 7 μm 2 The misorientation of each grain was analyzed for the above measurement area, excluding measurement points where the CI value was 0.1 or less at measurement intervals of 2.0 μm. Measurement points where the misorientation between adjacent measurement points was 15° or more were defined as grain boundaries. Using analysis software (EDAX / AMETEK OIM Analysis ver. 8.6), the average crystal grain size calculated by the Area Fraction method, excluding twin grain boundaries, was evaluated as "×" if it was greater than 800 μm, and as "◯" if it was 800 μm or less.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] [Table 4]

[0078] [Table 5]

[0079] [Table 6]

[0080] In Comparative Example 1-5, the area ratio of the crystal orientation in the surface (rolled surface) perpendicular to the plate thickness direction did not satisfy equation (1), and as a result of the joining test, the difference in maximum crystal grain size between the strip material for characteristic evaluation made from ingot A and the strip material for characteristic evaluation made from ingot B was large, at over 1000 μm, and the effect of suppressing the coarsening of crystal grains could not be stably exerted. In addition, in Comparative Example 6, the total content of group A elements was low at 1.4 mass ppm, and when the strip material for characteristic evaluation using ingot B was heat treated at 800°C for 1 hour, the average crystal grain size became larger than 800 μm, and coarsening of the crystal grains could not be sufficiently and stably suppressed.

[0081] In contrast, in Example 1-12 of the present invention, the area ratio of the crystal orientation in the surface (rolled surface) perpendicular to the plate thickness direction satisfied equation (1), and as a result of the joining test, the difference in maximum crystal grain size between the strip material for characteristic evaluation made from ingot A and the strip material for characteristic evaluation made from ingot B was less than 1000 μm, and the effect of suppressing the coarsening of crystal grains was stably exerted. In addition, in Example 1-12 of the present invention, the total content of group A elements was within the range of 2 massppm or more and 20 massppm or less, and when the strip material for characteristic evaluation using ingot B was heat treated at 800°C for 1 hour, the average crystal grain size was 800 μm or less, and coarsening of the crystal grains was sufficiently suppressed.

[0082] From the above, it was confirmed that, according to the present invention, even if 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 suppress the coarsening of crystal grains when joining a ceramic substrate and a copper material, and 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% or less, One or more A group 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 mass ppm to 20 mass ppm, The conductivity is 95% IACS or more, In a plane perpendicular to the thickness direction, the area ratios of the crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> are S (110), S (311), S (331), S (210), S (321), and S (211), respectively. A copper plate characterized by satisfying the following formula (1): (1) Formula: S(110)+S(311)+S(331)+S(210)+S(211)>S(321)

2. In a plane perpendicular to the thickness direction of the plate, the area ratios of the crystal orientations <110>, <311>, <331>, <210>, <321>, and <211> are S(110), S(311), S(331), S(210), S(321), and S(211), respectively, and satisfy the following relationship. Copper plate according to claim 1. 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. 2. The copper plate according to claim 1, characterized in that in a plane perpendicular to the plate thickness direction, the area ratio of crystal grains having an average crystal grain size Dave of 2 x Dave or more is 10% or less.

4. 2. The copper plate according to claim 1, wherein the copper plate contains one or more B group elements selected from Ca, Sr, and Ba in a total amount within the range of 10 ppm by mass to 200 ppm by mass.

5. An insulating substrate comprising a ceramic substrate and a copper plate bonded to at least one surface of the ceramic substrate, An insulating substrate, wherein the copper plate is formed from the copper plate according to any one of claims 1 to 4.

6. 6. The insulating substrate according to claim 5, wherein the ceramic substrate is made of any one of silicon nitride, alumina, and aluminum nitride.

7. 6. The insulating substrate according to claim 5, wherein a plating layer is formed on the surface of said copper plate opposite to said ceramic substrate.

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