Pure copper material, insulating substrate and electronic device

Abstract

In this pure copper material, the content of Cu is in the range of 99.9% by mass or more and 99.999% by mass or less. The average crystal grain size in the rolling surface is 10 μm or more, and 1 mm is measured by the EBSD method at a step size of 1 μm for the measurement interval. 2 For the measurement area of 1 mm or more, the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM are excluded. When the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the average value of LOS (Local Orientation Spread) is 2.00° or less.

Description

Technical Field

[0001] The present invention relates to a pure copper material suitable for electrical / electronic components such as heat sinks or thick copper circuits, and particularly to a pure copper material used in an insulating substrate on which a power semiconductor or the like is mounted, an insulating substrate using the pure copper material, and an electronic device.

[0002] This application claims priority based on Japanese Patent Application No. 2022-121432 filed on July 29, 2022, and Japanese Patent Application No. 2023-120990 filed on July 25, 2023, and incorporates their contents herein. Background Art

[0003] Conventionally, pure copper materials with high conductivity have been used in electrical / electronic components such as heat sinks or thick copper circuits.

[0004] In recent years, as the amount of current flowing through components for electrical / electronic devices has increased, resistance heating has become a problem.

[0005] In semiconductor devices or the like, for example, an insulating substrate such as a heat sink or a thick copper circuit formed by bonding a pure copper material to a ceramic substrate is used.

[0006] When bonding a ceramic substrate and a pure copper material, since a pressure treatment is performed in a high-temperature atmosphere, bonding defects, appearance defects, and defects in the inspection process may sometimes occur due to coarsening or non-uniform growth of the crystal grain size of the pure copper material.

[0007] To solve this problem, it is required that the pure copper material has a small change in crystal grain size and a uniform size even after heat treatment.

[0008] Therefore, for example, in Patent Documents 1 and 2, a technique for suppressing the growth of crystal grains in a pure copper material has been proposed.

[0009] It is described in Patent Document 1 that by containing 0.0006 to 0.0015 wt% of S, crystal grains of a certain size can be adjusted even when heat treatment is performed at a temperature above the recrystallization temperature.

[0010] In addition, in Patent Document 2, by containing Ca and specifying the ratio of the content of Ca to the total content of O, S, Se, and Te, coarsening of crystal grains can be suppressed even when heat treatment is performed at 800°C.

[0011] Patent Document 1: Japanese Unexamined Patent Application Publication No. 06-002058

[0012] Patent Document 2: International Publication No. 2020 / 203071

[0013] However, in Patent Documents 1 and 2, a configuration is adopted to suppress the coarsening of crystal grains by specifying the composition. However, depending on the heat treatment conditions and the like, it may not be possible to sufficiently suppress the coarsening of crystal grains or the deviation of crystal grain diameters.

[0014] In particular, when firmly bonding a ceramic substrate and a copper plate, high-temperature heat treatment is performed in a state where the ceramic substrate and the copper plate are pressed with a constant pressure in the stacking direction. At this time, in the copper plate, crystal grains tend to grow unevenly, and due to the coarsening or uneven growth of crystal grains, bonding defects, appearance defects, and defects in the inspection process may sometimes occur. Summary of the Invention

[0015] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a pure copper material in which the change in crystal grain diameter is small even after heat treatment, the deviation of crystal grain diameter is suppressed, and a uniform crystal structure can be obtained, an insulating substrate using the pure copper material, and an electronic device.

[0016] As a result of intensive studies by the present inventors to solve this problem, it has been found that in order to suppress the coarsening of crystal grains and the deviation of crystal grain diameters during heat treatment, it is important to control the "distribution of strain" inside the material.

[0017] That is, as the driving force for crystal grain growth generated during heat treatment, strain at the grain boundary or within the crystal grain can be cited. If substances that may become the driving force for crystal grain growth are unevenly present in the material, the growth of crystal grains will deviate, resulting in phenomena such as local coarsening or mixed grain formation of crystal grains. Therefore, it has been clarified that a material in which strain is uniformly dispersed is important for suppressing crystal grain growth during heat treatment.

[0018] In addition, mixed grain formation refers to a state in which the sizes of crystal grains are inconsistent and large crystal grains and small crystal grains coexist.

[0019] The present invention has been completed based on the above insights. The pure copper material of Scheme 1 of the present invention is characterized in that the content of Cu is in the range of 99.9% by mass or more and 99.999% by mass or less, the average crystal grain diameter in the rolling plane is 10 μm or more, and 1 mm is measured by the EBSD method at a step size of 1 μm. 2 For the above measurement area, excluding the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, the average value of LOS (Local Orientation Spread) when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary is 2.00° or less.

[0020] The pure copper material according to Embodiment 1 of the present invention has a Cu content in the range of more than 99.9% by mass and less than 99.999% by mass, so it has particularly excellent electrical conductivity and heat dissipation properties, and is particularly suitable as a raw material for components used in electrical / electronic devices for high-current applications.

[0021] Moreover, since the average crystal grain diameter in the rolling plane is 10 μm or more, the progress of recrystallization during heat treatment can be suppressed, and the coarsening of crystal grains and the non-uniformity of the structure can be suppressed.

[0022] Furthermore, since the average value of LOS measured by the EBSD method is 2.00° or less, the strain distribution within the crystal is homogenized. Even after heat treatment, the change in crystal grain diameter is small, and a uniform and fine crystal structure can be obtained.

[0023] In Embodiment 2 of the present invention, in the pure copper material of Embodiment 1, an area of 1 mm or more can be measured by the EBSD method at a measurement interval of 1 μm step. Excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the average value of GOS (Grain Orientation Spread) is 2.00° or less. 2

[0024] For the pure copper material according to Embodiment 2 of the present invention, since the average value of GOS measured by the EBSD method is 2.00° or less, the strain within the crystal grains does not localize. Even after heat treatment, the change in crystal grain diameter is further reduced, and a more uniform and fine crystal structure can be obtained.

[0025] In Embodiment 3 of the present invention, in the pure copper material of Embodiment 1 or Embodiment 2, an area of 1 mm or more can be measured by the EBSD method at a measurement interval of 1 μm step. Excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the standard deviation value of KAM (Kernel Average Misorientation) is 0.75° or less. 2

[0026] For the pure copper material according to Embodiment 3 of the present invention, since the standard deviation value of KAM measured by the EBSD method is 0.75° or less, the strain within the crystal grains does not localize. Even after heat treatment, the change in crystal grain diameter is further reduced, and a more uniform and fine crystal structure can be obtained.

[0027] ​​In the pure copper material of any one of Solutions 1 to 3 of the present invention, the Solution 4 can measure 1 mm at a step size of 1 μm by the EBSD method 2 or more of the measurement area, excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the average value of GND (Geometrically Necessary Dislocations) is 5.0×10 14 m -2 or less.

[0028] In the pure copper material according to Solution 4 of the present invention, since the amount of GN dislocations locally accumulated is controlled to be less, even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine crystal structure can be obtained.

[0029] The Solution 5 of the present invention can contain one or more additive elements selected from Ca, Sr, and Ba in the pure copper material of any one of Solutions 1 to 4 in a total amount of 300 mass ppm or less.

[0030] In the pure copper material according to Solution 5 of the present invention, when one or more additive elements selected from Ca, Sr, and Ba are contained in a total amount of 5 mass ppm or more and 300 mass ppm or less, the growth of grains during heat treatment can be further reliably suppressed without significantly affecting the material strength and conductivity. When the total amount of the additive elements is 0 mass ppm or more and less than 5 mass ppm, the above-mentioned effect is poor.

[0031] The Solution 6 of the present invention can have a compound containing at least one of the additive element and Cu in the pure copper material of Solution 5, and the number density of the compound is 1×10 -4 pieces / μm 2 or more.

[0032] In the pure copper material according to Solution 6 of the present invention, since the number density of the compound containing at least one of the additive element and Cu is 1×10 -4 pieces / μm 2 or more, the growth of grains during heat treatment can be further reliably suppressed by the pinning effect of the compound.

[0033] The Solution 7 of the present invention can have the compound containing one or more selected from Cu 5 Ca, Cu 5 Sr, and Cu 13 Ba in the pure copper material of Solution 6.

[0034] The pure copper material according to Embodiment 7 of the present invention, since the compound contains one or more selected from Cu 5 Ca, Cu 5 Sr, and Cu 13 Ba, etc., the growth of grains during heat treatment can be further reliably suppressed by the pinning effect of these compounds.

[0035] In the pure copper material of any one of Embodiments 1 to 7 of the present invention, Embodiment 8 of the present invention may contain one or more selected from S, Se, and Te in a total amount within a range of 10.0 mass ppm or less.

[0036] In the pure copper material according to Embodiment 8 of the present invention, when one or more selected from S, Se, and Te are contained in a total amount within a range of 0.2 mass ppm or more and 10.0 mass ppm or less, the growth of grains during heat treatment can be further reliably suppressed. When the total amount of one or more selected from S, Se, and Te is 0 mass ppm or more and less than 0.2 mass ppm, the above-mentioned effect is poor.

[0037] In the pure copper material of any one of Embodiments 1 to 8 of the present invention, Embodiment 9 of the present invention may set the content of O to 100 mass ppm or less.

[0038] In the pure copper material according to Embodiment 9 of the present invention, since the content of O is limited to 100 mass ppm or less, the growth of grains during heat treatment can be further suppressed.

[0039] In the pure copper material of any one of Embodiments 1 to 9 of the present invention, Embodiment 10 of the present invention may set the content of P within a range of 3.00 mass ppm or less.

[0040] In the pure copper material according to Embodiment 10 of the present invention, when the content of P is within a range of 0.01 mass ppm or more and 3.00 mass ppm or less, O contained as an impurity can be rendered harmless, and further, the growth of grains during heat treatment can be suppressed. When the content of P is 0 mass ppm or more and less than 0.01 mass ppm, the above-mentioned effect is poor.

[0041] In the pure copper material of Embodiment 5 of the present invention, Embodiment 11 of the present invention may have a mass ratio A / B of the total content A of Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O exceeding 1.0.

[0042] The pure copper material according to Embodiment 11 of the present invention can suppress the consumption of Ca, Sr, and Ba by forming compounds with P, S, Se, Te, and O because the mass ratio A / B of the total content A of Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O is within the above range, and can reliably exhibit the grain growth inhibition effect (the effect of suppressing the growth of grains) of Ca, Sr, and Ba.

[0043] Embodiment 12 of the present invention can contain one or more selected from Ag, Fe, and Pb in a total amount within a range of 50.0 mass ppm or less in the pure copper material of any one of Embodiments 1 to 11.

[0044] In the pure copper material according to Embodiment 12 of the present invention, when one or more selected from Ag, Fe, and Pb are contained in a total amount within a range of 0.5 mass ppm or more and 50.0 mass ppm or less, Ag, Fe, and Pb are dissolved in the copper matrix phase, thereby further suppressing the growth of grains during heat treatment. When the total amount of one or more selected from Ag, Fe, and Pb is 0 mass ppm or more and less than 0.5 mass ppm, the above-mentioned effect is poor.

[0045] Embodiment 13 of the present invention can contain Mg in a range of 100 mass ppm or less in the pure copper material of any one of Embodiments 1 to 12.

[0046] In the pure copper material according to Embodiment 13 of the present invention, when Mg is contained in an amount within a range of 1 mass ppm or more and 100 mass ppm or less, the growth of grains during heat treatment can be further suppressed. When the content of Mg is 0 mass ppm or more and less than 1 mass ppm, the above-mentioned effect is poor.

[0047] The insulating substrate according to Embodiment 14 of the present invention is characterized by including a ceramic substrate and a copper plate joined to one surface of the ceramic substrate, and the copper plate is made of the pure copper material of any one of Embodiments 1 to 13.

[0048] In the insulating substrate according to Embodiment 14 of the present invention, since the copper plate joined to the ceramic substrate is made of the pure copper material of any one of Embodiments 1 to 13, the growth of grains during joining can be suppressed, and it has a uniform crystal structure and can be used stably.

[0049] The electronic device according to Embodiment 15 of the present invention is characterized by having the insulating substrate of Embodiment 14 and electronic components mounted on the insulating substrate.

[0050] In the electronic device according to Embodiment 15 of the present invention, since it has the insulating substrate of Embodiment 14, the copper plate has a uniform crystal structure and can be used stably.

[0051] According to the solution of the present invention, it is possible to provide a pure copper material, an insulating substrate using the pure copper material, and an electronic device, which have small changes in crystal grain size even after heat treatment, suppress the deviation of crystal grain size, and can obtain a uniform and fine crystal structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic explanatory view of the insulating substrate and the electronic device of the present embodiment.

[0053] Figure 2 It is a flowchart of the manufacturing method of the pure copper material of the present embodiment.

[0054] Figure 3A It is the observation result of the compound in Example 11 of the present invention and is a TEM image (transmission electron image).

[0055] Figure 3B It is the observation result of the compound in Example 11 of the present invention and is an electron diffraction image. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] Hereinafter, a pure copper material, an insulating substrate, and an electronic device according to an embodiment of the present invention will be described.

[0057] The pure copper material of the present embodiment is used as a raw material for electrical / electronic components such as heat sinks or thick copper circuits. When forming the above electrical / electronic components, the pure copper material is joined to a ceramic substrate, for example, to form an insulating substrate.

[0058] Figure 1 FIG. shows an insulating substrate 10 according to an embodiment of the present invention and an electronic device 1 using the insulating substrate 10.

[0059] The electronic device 1 of the present embodiment includes: the insulating substrate 10 of the present embodiment; an electronic component 3 joined to one side (the upper side in Figure 1 FIG.) of the insulating substrate 10 through a first bonding layer 2; and a heat sink 51 joined to the other side (the lower side in Figure 1 FIG.) of the insulating substrate 10 through a second bonding layer 8.

[0060] In addition, in the present embodiment, the electronic component 3 is a power semiconductor element, and the electronic device 1 is a power module.

[0061] The insulating substrate 10 includes a ceramic substrate 11, a circuit layer 12 disposed on one surface (the upper surface in Figure 1 FIG.) of the ceramic substrate 11, and a metal layer 13 disposed on the other surface (the lower surface in Figure 1 FIG.) of the ceramic substrate 11.

[0062] The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13.

[0063] 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 the circuit layer 12, and one surface (the upper surface in Figure 1 this case) is set as the mounting surface for mounting the electronic component 3.

[0064] The metal layer 13 is formed by bonding a copper plate to the other surface of the ceramic substrate 11. The metal layer 13 has the effect of efficiently transferring heat from the electronic component 3 to the heat sink 51.

[0065] In addition, 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 bonded by existing bonding methods such as the DBC method and the AMB method, for example.

[0066] Here, the temperature during bonding becomes a high temperature condition of 750 °C or higher, for example, and coarsening of crystal grains may occur in the circuit layer 12 and the metal layer 13.

[0067] Therefore, in the present embodiment, the copper plate forming the circuit layer 12 and the copper plate forming the metal layer 13 are made of the pure copper material of the present embodiment.

[0068] In the pure copper material of the present embodiment, the content of Cu is in the range of 99.9 mass% or more and 99.999 mass% or less.

[0069] In addition, in the pure copper material of the present embodiment, one or more additive elements selected from Ca, Sr, and Ba can be included in the range of 5 mass ppm or more and 300 mass ppm or less in total amount.

[0070] And, in the pure copper material of the present embodiment, one or more selected from S, Se, and Te can be included in the range of 0.2 mass ppm or more and 10.0 mass ppm or less in total amount.

[0071] Moreover, in the pure copper material of the present embodiment, the content of O is preferably 100 mass ppm or less.

[0072] And, in the pure copper material of the present embodiment, the content of P can be in the range of 0.01 mass ppm or more and 3.00 mass ppm or less.

[0073] Moreover, in the pure copper material of the present embodiment, the mass ratio A / B of the total content A of Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O is preferably more than 1.0.

[0074] Moreover, in the pure copper material of the present embodiment, one or more selected from Ag, Fe, and Pb may be contained in a range of 0.5 mass ppm or more and 50.0 mass ppm or less in total amount.

[0075] Furthermore, in the pure copper material of the present embodiment, Mg may be contained in a range of 1 mass ppm or more and 100 mass ppm or less.

[0076] Moreover, in the pure copper material of the present embodiment, the average crystal grain size in the rolling plane is 10 μm or more, and 1 mm is measured by the EBSD method at a step size of 1 μm 2 For the measurement area of the above, excluding the measurement points (pixels) with a CI value of 0.1 or less analyzed by the data analysis software OIM, when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the average value of LOS (Local Orientation Spread) is set to 2.00° or less.

[0077] In addition, in the present embodiment, the "orientation difference" is also referred to as the "angle difference".

[0078] In addition, in the pure copper material of the present embodiment, it is preferable to measure 1 mm by the EBSD method at a step size of 1 μm 2 For the measurement area of the above, excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the average value of GOS (Grain Orientation Spread) is 2.00° or less.

[0079] Moreover, in the pure copper material of the present embodiment, it is preferable to measure 1 mm by the EBSD method at a step size of 1 μm 2 For the measurement area of the above, excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary, the standard deviation value of the KAM (Kernel Average Misorientation) value can be 0.75° or less.

[0080] Furthermore, in the pure copper material of the present embodiment, it is preferable to measure 1 mm by the EBSD method at a step size of 1 μm 2For the above measurement area, excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, the average value of GND (Geometrically Necessary Dislocations) when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary is 5.0×10 14 m -2 or less.

[0081] Moreover, in the pure copper material of the present embodiment, it preferably has a compound containing at least one of the above-mentioned additive elements and Cu, and the number density of this compound is 1×10 -4 pieces / μm 2 or more.

[0082] Furthermore, the above compound preferably contains one or more selected from Cu 5 Ca, Cu 5 Sr, and Cu 13 Ba.

[0083] Here, in the pure copper material of the present embodiment, the reasons for stipulating the content of Cu, the average crystal grain size, the average value of LOS, the average value of GOS, the standard deviation value of the KAM value, the average value of GND, the content of various elements, and the compound will be described below.

[0084] (Content of Cu: 99.9 mass% or more and 99.999 mass% or less)

[0085] In electrical / electronic components for high-current applications, in order to suppress heat generation during energization, excellent electrical conductivity and heat dissipation are required, and pure copper with particularly excellent electrical conductivity and heat dissipation is preferably used. And when bonding with a ceramic substrate or the like, in order to be able to relieve the thermal strain generated during the thermal cycling load, a small deformation resistance is preferred.

[0086] Therefore, in the pure copper material of the present embodiment, the purity of Cu is stipulated to be 99.9 mass% or more. In addition, the purity of Cu is preferably 99.965 mass% or more, and more preferably 99.97 mass% or more.

[0087] Moreover, when the purity of Cu exceeds 99.999 mass%, special refining processes are required, and the manufacturing cost will increase significantly. Therefore, in the pure copper material of the present embodiment, the purity of Cu is stipulated to be 99.999 mass% or less.

[0088] (Average crystal grain size in the rolling plane: 10 μm or more)

[0089] In the pure copper material of the present embodiment, if the grain size of the grains in the rolling surface is fine, for example, when the pure copper material is heated to 800 °C or higher, recrystallization is likely to occur, and grain coarsening and non-uniformity of the structure may be promoted.

[0090] Therefore, in the pure copper material of the present embodiment, in order to suppress grain coarsening and non-uniformity of the structure during heat treatment, the average crystal grain size in the rolling surface is set to 10 μm or more.

[0091] In addition, the average crystal grain size in the rolling surface is preferably 15 μm or more, more preferably 20 μm or more. Also, the average crystal grain size in the rolling surface is preferably 300 μm or less, more preferably 275 μm or less, and still more preferably 250 μm or less.

[0092] (Average value of LOS: 2.00° or less)

[0093] The LOS (Local Orientation Spread) value measured by EBSD is calculated by the angular difference between each point in the set kernel and all other points in the kernel. For example, since the shape of the pixel is a regular hexagon, when the nearest neighbor number is set to 1, six adjacent points are adjacent to one center point. If any two points are selected from the total seven points including the center point and the six adjacent points, the number of combinations of the two points is 21. The orientation difference between the two points of each of the 21 combinations is obtained, and the average value thereof is used as the LOS value. Moreover, the value obtained by averaging the LOS values for the measurement field of view is used as the average value of LOS. The LOS value is a strain value equivalent to taking into account the orientation difference between the pixels in the set kernel. The LOS value becomes a measurement value with little dependence on the step size during measurement.

[0094] In addition, in the present embodiment, the nearest neighbor number is set to 1, and the calculation is performed for pixels with an angular difference of 5° or less between the pixels. Based on this LOS value, the strain distribution in the crystal can be accurately evaluated.

[0095] Moreover, in the present embodiment, by setting the average value of LOS to 2.00° or less, even after heat treatment, the change in crystal grain size is small, and a uniform and fine crystal structure can be obtained.

[0096] In addition, the average value of LOS is preferably 1.75° or less, more preferably 1.50° or less. Also, the average value of LOS is preferably 0.05° or more, more preferably 0.10° or more, and still more preferably 0.20° or more.

[0097] (Average value of GOS: 2.00° or less)

[0098] The GOS (Grain Orientation Spread) value measured by EBSD is the average of the angular differences of each grain obtained after finding the angular differences between all pixels in the grain. Further, the value obtained by averaging the calculated GOS values for the measurement field of view is defined as the average GOS value. Here, for the average GOS value, the average is calculated using the number of each crystal instead of the size of the area of each crystal. That is, if the GOS value is large, it indicates strain localization within the grain. In addition, calculations are performed for pixels having an angular difference of 5° or less between pixels.

[0099] By controlling the GOS value to be low, strain will be present uniformly, enabling the growth of grains to occur uniformly and effectively suppressing the local occurrence of grain coarsening. Also, even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine crystal structure can be obtained.

[0100] Therefore, in the present embodiment, in order to sufficiently suppress the local occurrence of grain coarsening during heat treatment, it is preferable to set the average GOS value to 2.00° or less.

[0101] Further, the average GOS value is more preferably 1.90° or less, and even more preferably 1.80° or less. Also, the average GOS value is preferably 0.05° or more, more preferably 0.10° or more, and even more preferably 0.20° or more.

[0102] (Standard deviation value of KAM value: 0.75° or less)

[0103] The KAM (Kernel Average Misorientation) value measured by EBSD is the value calculated by averaging the orientation differences between one pixel and the pixels surrounding it. Since the shape of the pixel is a regular hexagon, when the nearest neighbor count is set to 1, the average of the orientation differences between one pixel and the six adjacent pixels is calculated as the KAM value. By using this KAM value, the local orientation difference, that is, the strain distribution, can be visualized. The standard deviation value of this KAM value represents the uniformity of local strain. In addition, calculations are performed for pixels having an angular difference of 5° or less between pixels.

[0104] By controlling the standard deviation value of the KAM value to be low, strain will be present uniformly, enabling the growth of grains to occur uniformly and effectively suppressing the local occurrence of grain coarsening. Also, even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine crystal structure can be obtained.

[0105] Therefore, in the present embodiment, in order to sufficiently suppress the local occurrence of grain coarsening during heat treatment, it is preferable to set the standard deviation value of the KAM value to 0.75° or less.

[0106] Furthermore, the standard deviation value of the KAM value is more preferably 0.70° or less, and even more preferably 0.65° or less. Also, the standard deviation value of the KAM value is preferably 0.025° or more, more preferably 0.05° or more, and even more preferably 0.075° or more.

[0107] (Average value of GND: 5.0×10 14 m -2 or less)

[0108] The GND (Geometrically Necessary Dislocations) value measured by EBSD is a value for evaluating the amount of GN dislocations by measuring the orientation of each pixel. By using this GND value, it is possible to evaluate the locally accumulated GN dislocations. The {111}<110> is used as the slip system, and 0.255 nm is used as the magnitude of the Burgers vector at this time for calculation. In addition, the nearest neighbor number is set to 1, and the calculation is performed for pixels with an angular difference of 5° or less between pixels.

[0109] By controlling the average value of this GND to be low, the locally accumulated GN dislocations will decrease, and it is possible to further effectively suppress the growth of grains during heat treatment.

[0110] Therefore, in the present embodiment, it is preferable to set the average value of GND to 5.0×10 14 m -2 or less. Thereby, it is possible to further suppress the coarsening of grains during heat treatment, and even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine crystal structure can be obtained.

[0111] Furthermore, the average value of GND is more preferably 4.5×10 14 m -2 or less, and even more preferably 4.0×10 14 m -2 or less. Also, the average value of GND is preferably 0.4×10 14 m -2 or more, more preferably 0.6×10 14 m -2 or more, and even more preferably 0.8×10 14 m -2 or more.

[0112] (Total content of one or more additive elements selected from Ca, Sr, and Ba: 5 mass ppm or more and 300 mass ppm or less)

[0113] One or more additive elements selected from Ca, Sr, and Ba hardly dissolve in the copper matrix phase and form compounds. Moreover, since they are elements that tend to be unevenly distributed at grain boundaries, they can pin grain boundaries with a very small addition amount and can effectively suppress the growth of grains during heat treatment. Therefore, by adding one or more additive elements selected from Ca, Sr, and Ba, the growth of grains during heat treatment can be further suppressed with little change in the strength and conductivity of the material.

[0114] Moreover, regarding the effects of these additive elements, it is known that the effects are enhanced by controlling them simultaneously with the average value of the above-mentioned LOS. When recrystallization nuclei generated by heat treatment grow, in the presence of additive elements having a pinning effect, the growth of these recrystallization nuclei can be suppressed, and a state of finer grains can be maintained.

[0115] On the other hand, if the content of one or more additive elements selected from Ca, Sr, and Ba is too high, it may have an adverse effect on manufacturability.

[0116] Therefore, in the present embodiment, in order to further suppress the growth of grains during heat treatment, it is preferable to set the total content of one or more additive elements selected from Ca, Sr, and Ba within the range of 5 mass ppm or more and 300 mass ppm or less.

[0117] In addition, the total content of one or more additive elements selected from Ca, Sr, and Ba is more preferably 7.5 mass ppm or more, and even more preferably 10 mass ppm or more. Also, the total content of one or more additive elements selected from Ca, Sr, and Ba is more preferably 250 mass ppm or less, and even more preferably 200 mass ppm or less.

[0118] (Number density of compounds containing at least one of the additive element and Cu: 1×10 -4 pieces / μm 2 or more))

[0119] Since a large number of compounds containing at least one of Ca, Sr, Ba, and Cu exist, grain boundaries can be pinned, and the growth of grains during heat treatment can be effectively suppressed.

[0120] Therefore, in the present embodiment, in order to further suppress the growth of grains during heat treatment, the number density of compounds containing at least one of the additive element and Cu is preferably 1×10 -4 pieces / μm 2Above.

[0121] In addition, the number density of the compound containing at least one of the additive element and Cu is further preferably 5×10 -4 pieces / μm 2 or more, more preferably 10×10 -4 pieces / μm 2 or more. Moreover, the number density of the compound containing at least one of the additive element and Cu is preferably 1000×10 -4 pieces / μm 2 or less, further preferably 900×10 -4 pieces / μm 2 or less, more preferably 800×10 -4 pieces / μm 2 or less.

[0122] Here, as the compound containing at least one of the additive element and Cu, it is preferably selected from Cu 5 Ca, Cu 5 Sr, and Cu 13 Ba, one or more than two.

[0123] (Total content of one or more than two selected from S, Se, and Te: 0.2 mass ppm or more and 10.0 mass ppm or less)

[0124] Elements such as S, Se, and Te have the effect of suppressing the coarsening of crystal grains by suppressing grain boundary movement and reducing the hot workability. In the case of containing a large amount of elements such as S, Se, and Te, the hot workability may decrease.

[0125] Therefore, in the present embodiment, in order to ensure the hot workability and further effectively suppress the coarsening of crystal grains during heat treatment, it is preferable to set the total content of one or more than two selected from S, Se, and Te within the range of 0.2 mass ppm or more and 10.0 mass ppm or less.

[0126] In addition, the total content of one or more than two selected from S, Se, and Te is preferably 0.5 mass ppm or more, further preferably 2.0 mass ppm or more. Moreover, the total content of one or more than two selected from S, Se, and Te is preferably 7.5 mass ppm or less, further preferably 5.0 mass ppm or less.

[0127] (Content of O: 100 mass ppm or less)

[0128] O (oxygen) contained as an impurity in the pure copper material is an element having the effect of promoting the growth of crystal grains.

[0129] Therefore, in the present embodiment, in order to further effectively suppress the growth of grains during heat treatment, it is preferable to limit the content of O to 100 mass ppm or less.

[0130] In addition, the content of O is more preferably 75 mass ppm or less, and even more preferably 50 mass ppm or less. Also, the content of O is preferably 0.1 mass ppm or more, more preferably 0.3 mass ppm or more, and even more preferably 0.5 mass ppm or more.

[0131] (P: 0.01 mass ppm or more and 3.00 mass ppm or less)

[0132] P is widely used as an element to render oxygen harmless in copper. However, when the content of P is above a certain amount, it not only hinders the action of oxygen but also hinders the action of grain growth inhibiting elements (elements that inhibit the growth of grains) present at grain boundaries. Therefore, when heated to a high temperature, the elements that inhibit the growth of grains cannot fully exert their effects, and thus coarsening and non-uniformity of grains may occur.

[0133] Therefore, in the present embodiment, it is preferable to set the content of P to 0.01 mass ppm or more and 3.00 mass ppm or less.

[0134] In addition, the content of P is preferably 2.50 mass ppm or less, and more preferably 2.00 mass ppm or less.

[0135] (The mass ratio A / B of the total content A of one or more additive elements selected from Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O: exceeding 1.0)

[0136] One or more additive elements selected from Ca, Sr, and Ba form compounds with elements such as P, S, Se, Te, and O. Therefore, when a large amount of P, S, Se, Te, and O are present, it may not be possible to sufficiently form compounds containing one or more additive elements selected from Ca, Sr, and Ba and Cu, and it may not be possible to better exert the pinning effect.

[0137] Therefore, in the present embodiment, it is preferable that the mass ratio A / B of the total content A of one or more additive elements selected from Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O exceeds 1.0.

[0138] In addition, the mass ratio A / B of the total content A of one or more additive elements selected from Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O is more preferably 1.5 or more, and even more preferably 2.0 or more. Also, the mass ratio A / B is preferably 100 or less, more preferably 75 or less, and even more preferably 50 or less.

[0139] (Total content of one or more selected from Ag, Fe, and Pb: 0.5 mass ppm or more and 50.0 mass ppm or less)

[0140] Ag, Fe, and Pb are elements that have the effect of suppressing grain coarsening by dissolving in the copper matrix phase. On the other hand, when a large amount of Ag, Fe, and Pb is contained, it may lead to an increase in manufacturing cost and a decrease in conductivity.

[0141] Therefore, in the present embodiment, it is preferable to set the total content of one or more selected from Ag, Fe, and Pb in the range of 0.5 mass ppm or more and 50.0 mass ppm or less.

[0142] In addition, the total content of one or more selected from Ag, Fe, and Pb is further preferably 2.0 mass ppm or more, more preferably 5.0 mass ppm or more. On the other hand, the total content of one or more selected from Ag, Fe, and Pb is further preferably 40.0 mass ppm or less, more preferably 30.0 mass ppm or less.

[0143] (Mg: 1 mass ppm or more and 100 mass ppm or less)

[0144] Mg is an element that has the effect of suppressing particle growth of grains. On the other hand, if a large amount of Mg is contained, it may have an adverse effect on productivity.

[0145] Therefore, in the present embodiment, it is preferable to set the content of Mg in the range of 1 mass ppm or more and 100 mass ppm or less.

[0146] In addition, the content of Mg is further preferably 2 mass ppm or more, more preferably 3 mass ppm or more. On the other hand, the content of Mg is further preferably 90 mass ppm or less, more preferably 80 mass ppm or less.

[0147] (Other inevitable impurities)

[0148] Examples of inevitable impurities contained in the remaining portion other than the elements with the above-determined contents include Al, As, B, Be, Bi, Cd, Cr, Sc, rare earth elements, V, Nb, Ta, Mo, Ni, W, Mn, Re, Ru, Ti, Os, Co, Rh, Ir, Pd, Pt, Au, Zn, Zr, Hf, Hg, Ga, In, Ge, Y, Tl, N, Sb, Si, Sn, Li, etc. These inevitable impurities may be contained within a range that does not affect the characteristics.

[0149] Here, these inevitable impurities may reduce the conductivity, so preferably they are 0.04% by mass or less, more preferably 0.03% by mass or less, still more preferably 0.02% by mass or less, and even more preferably 0.01% by mass or less in total amount.

[0150] Moreover, the content of each of these inevitable impurities is preferably 30 mass ppm or less, more preferably 20 mass ppm or less, still more preferably 15 mass ppm or less.

[0151] Next, with reference to Figure 2 the flowchart shown, the manufacturing method of the pure copper material of this embodiment having such a configuration will be described.

[0152] (Melting / Casting Process S01)

[0153] First, in the copper melt obtained by melting the oxygen-free copper raw material, the above elements are added to adjust the composition to produce a copper alloy melt. In addition, for the addition of various elements, elemental monomers or master alloys can be used. And the raw materials containing the above elements can be melted together with the copper raw material. Here, the copper melt is preferably so-called 4N Cu with a purity of 99.99% by mass or more, or so-called 5N Cu with a purity of 99.999% by mass or more.

[0154] In the melting process, in order to reduce the hydrogen concentration, it is preferably melted in an inert gas atmosphere (such as Ar gas) with a low vapor pressure of H 2 2O, and the holding time during melting is limited to the minimum. Then, the copper alloy melt whose composition has been adjusted is poured into a mold to produce an ingot. In addition, when considering mass production, a continuous casting method or a semi-continuous casting method is preferably used.

[0155] (First Hot Rolling Process S02)

[0156] In order to introduce stress to the obtained ingot and deform the shape into a specified size, hot working is performed. By introducing strain, high strain can be applied in a state of coarse grains, so the homogeneity of the material can be improved.

[0157] Here, the hot rolling temperature is set to a high temperature of 650 °C or more, and the average reduction ratio (average rolling ratio in one pass of rolling) in one pass of rolling is set to 15% or more, whereby strain can be uniformly introduced at a high temperature, and thus a structure with high homogeneity can be formed. In order to break the casting structure, the total rolling ratio here is preferably 50% or more, more preferably 55% or more, still more preferably 60% or more.

[0158] (Second Hot Rolling Process S03)

[0159] In order to further homogenize the strain, the hot-rolled material obtained through the first hot-rolling process S02 is reheated, and the second hot-rolling process S03 is carried out.

[0160] Here, in the second hot-rolling process S03, a high-temperature condition of 650 °C or higher, which is equal to or higher than that of the first hot-rolling process S02, is set. By setting the average reduction rate (average rolling rate per pass) of one-pass rolling to 15% or more, a structure with high homogeneity can be formed. In order to break the as-cast structure, the total rolling rate here is preferably 50% or more, more preferably 55% or more, and still more preferably 60% or more.

[0161] (Cold-rolling process S04)

[0162] Next, the copper raw material after the second hot-rolling process S03 is cold-rolled and processed into a specified shape.

[0163] In addition, the temperature condition in this cold-rolling process S04 is not particularly limited, but it is preferably carried out in the range of -200 °C or higher and 200 °C or lower. In the cold-rolling process S04, in order to introduce uniform strain throughout the material, rolling with a high reduction rate (rolling rate) of 15% or more per pass is required. In addition, since the cold-rolling process S04 is a cold working process, if the processing is carried out at a low reduction rate, the frictional force with the material surface acts strongly, preferentially introducing strain into the surface in the thickness direction or the crystal in the orientation where strain is easily introduced, resulting in non-uniformity of the structure. Therefore, in order to increase the compressive stress element, rolling must be carried out at a high reduction rate. It is necessary to carry out this high-reduction-rate rolling multiple times to make it into a specified shape. And the total processing rate is preferably 15% or more, more preferably 50% or more.

[0164] (Heat-treatment process S05)

[0165] Next, the copper raw material after the cold-rolling process S04 is heat-treated. Here, the heat-treatment method is not particularly limited, but it is preferably carried out in a non-oxidizing or reducing atmosphere. The heat-treatment temperature is preferably set to a high temperature of 750 °C or higher, and heat-treatment is carried out at this temperature for a short time of 1 hour or less. And the heating rate until the heat-treatment temperature is preferably 100 °C / minute or more.

[0166] For the uniformly introduced strain, by carrying out heat-treatment under high-temperature and short-time conditions, recrystallization of each recrystallization nucleus is carried out uniformly and simultaneously. In addition, in the case of heat-treatment at a low temperature below 750 °C or heat-treatment with a heating rate lower than 100 °C / minute, the growth of recrystallization nuclei will deviate, and as a result, a non-uniform structure will be formed.

[0167] The cooling method is not particularly limited, but a method with a cooling rate of 200 °C / min or more such as water quenching is preferred.

[0168] Moreover, in order to homogenize the recrystallized structure, the cold rolling process S04 and the heat treatment process S05 can be repeated two or more times.

[0169] (Temper rolling process S06)

[0170] In order to adjust the material strength, temper rolling can be performed on the copper raw material after the heat treatment process S05. In the case where low material strength is required, temper rolling can be omitted.

[0171] In the case of performing rolling, in order to uniformly introduce the strain of rolling, the rolling must introduce the strain in one pass. If rolling is performed at a rolling rate exceeding 20%, non-uniformity of the structure will be caused. Therefore, the rolling rate is preferably 20% or less.

[0172] In addition, the final thickness is not particularly limited. For example, a thickness in the range of 0.5 mm or more and 5 mm or less is preferred.

[0173] Through the above respective processes, the pure copper material (pure copper plate) of the present embodiment can be produced.

[0174] According to the pure copper material of the present embodiment configured as above, since the content of Cu is in the range of 99.9 mass% or more and 99.999 mass% or less, the electrical conductivity and heat dissipation are particularly excellent, and it is particularly suitable as a raw material for components of electrical / electronic devices for high-current applications.

[0175] Moreover, in the pure copper material of the present embodiment, since the average crystal grain diameter in the rolling plane is 10 μm or more, recrystallization during heat treatment can be suppressed, and thus growth of crystal grains and non-uniformity of the structure can be suppressed.

[0176] Furthermore, in the pure copper material of the present embodiment, the average value of LOS measured by the EBSD method is 2.00° or less. Therefore, the strain distribution within the crystal grains is homogenized, the change in crystal grain diameter is small even after heat treatment, and the deviation of crystal grain diameter is suppressed, and thus a uniform and fine structure can be obtained.

[0177] The method for obtaining a highly uniform structure is not limited to a specific method. For example, it is achieved by controlling the average reduction rate of the first hot rolling process, the second hot rolling process, and the cold rolling process, and the heat treatment temperature and heating rate of the heat treatment process as described above.

[0178] Here, in the pure copper material of the present embodiment, 1 mm is measured by the EBSD method at a step size of 1 μm for the measurement interval 2For the measurement area described above, when excluding measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the average value of GOS (Grain Orientation Spread) is 2.00° or less when considering boundaries with an orientation difference of 5° or more between adjacent pixels as grain boundaries, the strain within the grains is not localized. Even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine microstructure can be obtained.

[0179] Moreover, in the pure copper material of the present embodiment, when measuring 1 mm at a measurement interval of 1 μm step by the EBSD method 2 For the measurement area described above, when excluding measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the standard deviation value of KAM (Kernel Average Misorientation) is 0.75° or less when considering boundaries with an orientation difference of 5° or more between adjacent pixels as grain boundaries, the strain within the grains is not localized. Even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine microstructure can be obtained.

[0180] Furthermore, in the pure copper material of the present embodiment, when measuring 1 mm at a measurement interval of 1 μm step by the EBSD method 2 For the measurement area described above, when excluding measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the average value of GND (Geometrically Necessary Dislocations) is 5.0×10 14 m -2 or less, the amount of locally accumulated GN dislocations is controlled to be less. Therefore, even after heat treatment, the change in crystal grain size is further reduced, and a more uniform and fine microstructure can be obtained.

[0181] Moreover, in the pure copper material of the present embodiment, when containing one or more additive elements selected from Ca, Sr, and Ba in the range of 5 mass ppm or more and 300 mass ppm or less in total, the growth of grains can be suppressed by one or more additive elements selected from Ca, Sr, and Ba. Thus, the growth of grains during heat treatment can be further reliably suppressed without significantly affecting the material strength and conductivity.

[0182] Furthermore, in the pure copper material of the present embodiment, when having a compound containing at least one of Ca, Sr, Ba, and Cu and the number density of the compound is 1×10 -4 pieces / μm 2When it is above, the pinning effect of the compound can further reliably suppress the growth of grains during heat treatment.

[0183] Moreover, in the pure copper material of the present embodiment, when a compound containing at least one of Ca, Sr, Ba, and Cu contains one or more selected from Cu 5 Ca, Cu 5 Sr, and Cu 13 Ba, the growth of grains during heat treatment can be further reliably suppressed by the pinning effect of these compounds.

[0184] Furthermore, in the pure copper material of the present embodiment, when one or more selected from S, Se, and Te are contained in the range of 0.2 mass ppm or more and 10.0 mass ppm or less in total, grain boundary migration can be suppressed without significantly reducing hot workability, and thus the growth of grains during heat treatment can be further reliably suppressed.

[0185] Moreover, in the pure copper material of the present embodiment, when the content of O is 100 mass ppm or less, the content of O as an element promoting grain growth can be sufficiently suppressed, and the growth of grains during heat treatment can be further suppressed.

[0186] Furthermore, in the pure copper material of the present embodiment, when the content of P is in the range of 0.01 mass ppm or more and 3.00 mass ppm or less, O promoting grain growth can be rendered harmless, and the situation of hindering the action of grain growth inhibiting elements present at grain boundaries can be suppressed.

[0187] Moreover, in the pure copper material of the present embodiment, when the mass ratio A / B of the total content A of Ca, Sr, Ba to the total content B of P, S, Se, Te, O exceeds 1.0, the situation where Ca, Sr, Ba are consumed by forming compounds with P, S, Se, Te, O can be suppressed, and the grain growth inhibiting effect of Ca, Sr, Ba can be reliably exerted.

[0188] Furthermore, in the pure copper material of the present embodiment, when one or more selected from Ag, Fe, and Pb are contained in the range of 0.5 mass ppm or more and 50.0 mass ppm or less in total, Ag, Fe, Pb are dissolved in the copper matrix phase, thereby further suppressing the growth of grains during heat treatment.

[0189] Moreover, in the pure copper material of the present embodiment, when Mg is contained in the range of 1 mass ppm or more and 100 mass ppm or less, the coarsening of grains after heat treatment can be further suppressed by the grain growth inhibiting effect of Mg.

[0190] In the insulating substrate 10 of the present embodiment, there are a ceramic substrate 11, a circuit layer 12 joined to one surface of the ceramic substrate 11, and a metal layer 13 joined to the other surface of the ceramic substrate 11. The copper plates forming the circuit layer 12 and the metal layer 13 are made of the pure copper material of the present embodiment. Therefore, the growth of crystal grains during the joining with the ceramic substrate 11 can be suppressed, and the deviation of crystal grain diameters can be suppressed, so that it has a uniform crystal structure and can be stably used.

[0191] In the electronic device 1 of the present embodiment, since it has the above-mentioned insulating substrate 10 and electronic components 3 mounted on the circuit layer 12 of the insulating substrate 10, the copper plates forming the circuit layer 12 and the metal layer 13 have a uniform crystal structure and can be stably used.

[0192] As described above, the pure copper material as an embodiment of the present invention has been described, but the present invention is not limited thereto, and can be appropriately changed within the scope not departing from the technical gist of the invention.

[0193] For example, in the above embodiment, an example of the manufacturing method of the pure copper material has been described, but the manufacturing method of the pure copper material is not limited to the method described in the embodiment, and an existing manufacturing method can also be appropriately selected for manufacturing.

[0194] Moreover, the above manufacturing method has a rolling process, and the pure copper material of the present embodiment can also be called a pure copper rolled material.

[0195] Examples

[0196] Hereinafter, the results of the confirmation experiment conducted to confirm the effects of the present invention will be described.

[0197] The P concentration was purified to 0.001 mass ppm or less by the zone melting purification method, thereby obtaining pure copper with a purity of 99.999 mass% or more. The raw material composed of this pure copper was put into a high-purity graphite crucible and melted by high-frequency induction heating in an atmosphere furnace set to an Ar gas atmosphere.

[0198] Using 6N (purity 99.9999 mass% or more) high-purity copper and 2N (purity 99 mass% or more) elements, a master alloy containing 1 mass% of various elements was produced. The master alloy was added to the obtained copper melt, and the composition shown in Tables 1 and 2 was prepared to obtain a copper alloy melt. The obtained copper alloy melt was poured into a graphite mold to produce an ingot.

[0199] In addition, the size of the ingot was set to a thickness of about 100 mm × a width of about 100 mm × a length of about 150 - 200 mm.

[0200] The obtained ingot was heated at 900 °C for 4 hours in an Ar gas atmosphere. In order to meet the final pass temperature conditions shown in Tables 3 and 4, it was left to stand by in the atmosphere, and the first hot rolling process was carried out. In addition, the final pass temperature of the first hot rolling process was measured with a radiation thermometer. After the first hot rolling was completed, water cooling was carried out.

[0201] Next, in an Ar gas atmosphere, it was heated again at 900 °C for 4 hours. In order to meet the final pass temperature conditions shown in Tables 3 and 4, it was left to stand by in the atmosphere, and the second hot rolling process was carried out. In addition, the final pass temperature of the second hot rolling process was measured with a radiation thermometer. After the second hot rolling was completed, water cooling was also carried out.

[0202] Next, surface grinding was carried out to remove the oxide film formed in the first and second hot rolling processes, and it was cut to a specified size. Then, the thickness was appropriately adjusted to the final thickness, and cutting was carried out.

[0203] For each of the cut hot-rolled copper raw materials, rough machining (cold rolling) and heat treatment were carried out under the conditions described in Tables 3 and 4. A salt bath was used for the heat treatment, and it was confirmed that the heating rate (temperature rising rate) was 100 °C / min or more. Then, temper rolling was carried out under the conditions described in Tables 3 and 4, and strip-shaped materials (pure copper materials) for property evaluation with a thickness of 0.8 mm and a width of about 100 mm were produced respectively.

[0204] Moreover, the following items were evaluated.

[0205] (Composition analysis)

[0206] Measurement samples were collected from the obtained ingot. The contents of S and O were measured by the infrared absorption method, and the contents of other elements were measured by using a glow discharge mass spectrometer (GD-MS). In addition, the measurement was carried out at two places, the central part of the sample and the end part in the width direction, and the one with the higher content was taken as the content of the sample.

[0207] (Average crystal grain size)

[0208] A 20 mm × 20 mm sample was cut out from the obtained strip-shaped material for property evaluation, and the average crystal grain size was obtained by an SEM-EBSD (Electron Backscatter Diffraction Patterns) measuring device. The conditions of the electron microscope and the conditions of the EBSD detector are shown below.

[0209] (Conditions of the electron microscope)

[0210] Observation magnification or area of the measurement field of view: 400 μm × 800 μm

[0211] Accelerating voltage: 20 kV

[0212] Working distance: 20 mm

[0213] Specimen tilt angle: 70°

[0214] (Conditions of EBSD detector)

[0215] Name of analysis software: OIM DataAnalysis ver. 8.6 manufactured by EDAX / TSL Corporation (now AMETEK Corporation). CI value (reliability index): Measurement points with a value greater than 0.1 were used for analysis.

[0216] Grain boundary misorientation angle: A misorientation of 5° or more was considered a grain boundary.

[0217] Minimum grain size: Two or more steps were considered a grain.

[0218] Step size: 1 μm

[0219] Treatment of twins: Twins were considered grain boundaries.

[0220] The rolling surface was mechanically polished using water-resistant abrasive paper and diamond abrasive grains. Subsequently, fine polishing was performed using a colloidal silica solution. Then, using a scanning electron microscope, an electron beam was irradiated onto each measurement point (pixel) within the measurement range on the specimen surface, and through orientation analysis based on the electron backscatter diffraction method, the boundary between measurement points with an orientation difference of 5° or more between adjacent measurement points was set as a grain boundary. The boundary between measurement points with an orientation difference of more than 5° and less than 15° between adjacent measurement points was set as a small-angle grain boundary. The boundary between measurement points with an orientation difference of 15° or more between adjacent measurement points was set as a large-angle grain boundary. At this time, the twin boundary was also set as a large-angle grain boundary. Also, the measurement range was adjusted so that each sample contained 100 or more grains. Based on the obtained orientation analysis results, a grain boundary map was made using large-angle grain boundaries. In accordance with the cutting method of JIS H 0501, for the grain boundary map, five line segments of a specified length were drawn at specified intervals in the longitudinal and transverse directions. The number of grains that were completely cut was counted, and the average value of their cutting lengths was calculated as the average crystal grain size.

[0221] (Average value of LOS)

[0222] A 20 mm × 20 mm sample was cut from the strip for property evaluation, and the rolling surface was mechanically polished using waterproof abrasive paper and diamond abrasive grains. Subsequently, fine polishing was performed using a colloidal silica solution. Using an EBSD measurement device (Quanta FEG 450 manufactured by FEI Company, OIM Data Collection manufactured by EDAX / TSL Company (now AMETEK Company)) and analysis software (OIM Data Analysis ver.8.6 manufactured by EDAX / TSL Company (now AMETEK Company)), under the condition that the acceleration voltage of the electron beam was 15 kV, with a measurement interval of 1 μm step size, in an area of 1 mm 2 or more, the rolling surface (observation surface) of the specimen was measured by the EBSD method. The conditions of the electron microscope and the EBSD detector other than the acceleration voltage of the electron beam were the same as those in the measurement of the average crystal grain size described above. The measurement results were analyzed using the data analysis software OIM to obtain the CI (Confidence Index) value of each measurement point. Excluding the measurement points with a CI value of 0.1 or less, the orientation difference analysis of each crystal grain was performed using the data analysis software OIM. The boundary between pixels with an orientation difference of 5° or more between adjacent pixels was regarded as a grain boundary for analysis, and the LOS value of all pixels was obtained. The nearest neighbor number was set to 1, and for the seven points composed of the center point and six adjacent points, the orientation difference between each two points was obtained, and its average value was taken as the LOS value. The average value (number average) of the LOS values in the measurement area was obtained and recorded in Tables 5 and 6 as the average value of LOS.

[0223] (Average value of GOS)

[0224] Using the same specimen and device as for the evaluation of LOS, under the condition that the acceleration voltage of the electron beam was 15 kV, with a measurement interval of 1 μm step size, in an area of 1 mm 2 or more, the rolling surface (observation surface) of the specimen was measured by the EBSD method. The conditions of the electron microscope and the EBSD detector other than the acceleration voltage of the electron beam were the same as those in the measurement of the average crystal grain size described above. Excluding the measurement points with a CI value of 0.1 or less, the orientation difference analysis of each crystal grain was performed using the data analysis software OIM. The boundary between pixels with an orientation difference of 5° or more between adjacent pixels was regarded as a grain boundary for analysis, and the GOS value of all crystal grains was obtained. The average value of GOS was obtained by dividing the total value by the number of crystal grains (Number).

[0225] (Standard deviation value of KAM value)

[0226] Using the same specimens and apparatus as those for the evaluation of LOS, under the condition that the acceleration voltage of the electron beam is 15 kV, with a measurement interval of 1 μm step size, in a measurement area of 1 mm 2 or more, the rolling surface (observation surface) of the specimen was measured by the EBSD method. The conditions of the electron microscope except for the acceleration voltage of the electron beam and the conditions of the EBSD detector were the same as those in the measurement of the average crystal grain size described above. Excluding the measurement points with a CI value of 0.1 or less, the orientation difference analysis of each crystal grain was carried out using the data analysis software OIM. The number of nearest neighbors was set to 1, and the boundary between pixels with an orientation difference of 5° or more between adjacent pixels was regarded as a grain boundary for analysis, and the KAM value of all pixels was obtained. Then, the standard deviation value of the KAM value was obtained.

[0227] (Average value of GND)

[0228] Using the same specimens and apparatus as those for the evaluation of LOS, under the condition that the acceleration voltage of the electron beam is 15 kV, with a measurement interval of 1 μm step size, in a measurement area of 1 mm 2 or more, the rolling surface (observation surface) of the specimen was measured by the EBSD method. The conditions of the electron microscope except for the acceleration voltage of the electron beam and the conditions of the EBSD detector were the same as those in the measurement of the average crystal grain size described above. Excluding the measurement points with a CI value of 0.1 or less, the orientation difference analysis of each crystal grain was carried out using the data analysis software OIM. The boundary between pixels with an orientation difference of 5° or more between adjacent pixels was regarded as a grain boundary for analysis, and the GND value of all pixels was obtained and its average value was calculated. In addition, the slip system was {111}<110>, and for the <1-10> direction of the FCC(111) plane, 0.255 nm was used as the magnitude of the Burgers vector to calculate the GN dislocation density. And in order to reduce the error factor, the upper limit of the GND value was set to 1.0×10 16 m -2 , and the average value (number average) was calculated in the region of values below it.

[0229] (Number density of compounds)

[0230] Measurement specimens were collected from the characteristic evaluation bar stock, and the rolling surface was subjected to CP polishing. Using FE-SEM (field emission scanning electron microscope), 50 regions were observed at a magnification of 2000 times (about 2500 μm 2 / field of view). Based on the observation results in 50 regions, the number density of compounds containing at least one of Ca, Sr, Ba, and Cu was calculated.

[0231] (Identification of compounds)

[0232] Using the FIB (Focused Ion Beam) method, a sample for observing a compound was fabricated from a strip for property evaluation. For this sample, particle observation was carried out using a transmission electron microscope (TEM: manufactured by JEOL Ltd., JEM-2010F), and EDX analysis (energy dispersive X-ray spectroscopy) was performed to confirm whether the compound was particles containing one or more elements selected from Ca, Sr, Ba, and Cu.

[0233] Furthermore, EDX analysis and electron diffraction analysis were performed on the observed compound to confirm whether the compound contained one or more selected from Cu 5 Ca (space group P6 / mmm (191)), Cu 5 Sr (space group P6 / mmm (191)) and Cu 13 Ba (Fm-3c (226)).

[0234] Here, in Figure 3A , Figure 3B the observation results of the compound in Example 11 of the present invention are shown. It was confirmed that the observed compound contained Cu 5 Ca.

[0235] In the column of "presence or absence of compound" in Tables 5 and 6, based on the above observation results, the case where a compound containing one or more selected from Cu 5 Ca, Cu 5 Sr and Cu 13 Ba was observed was expressed as "B" (present), and the case where it was not observed was expressed as "D" (absent).

[0236] (Average crystal grain size d ave )

[0237] A 40 mm × 40 mm sample was cut out from the above strip for property evaluation. A paste-like active silver solder (TB-608T manufactured by TOKYO BLAZE CO., LTD.) was coated on both sides of a ceramic plate (material: Si 3 N 4 , 50 mm × 50 mm × thickness 0.32 mm). A ceramic plate was sandwiched between two of the above samples (pure copper plates), and heat treatment was carried out under a load with a pressing pressure of 0.59 MPa. Heat treatment was carried out under the following conditions. The stacked pure copper plates and ceramic plate were put into a furnace at 850 °C, and after confirming that the material temperature reached 850 °C with a thermocouple, it was held for 60 minutes. After the heating was completed, furnace cooling (cooling in the furnace) was carried out until it reached room temperature. After the temperature dropped to room temperature, the average crystal grain size d ave was measured for the rolling surface of the pure copper plate by the following method.

[0238] First, the rolling surface (the surface not in contact with the ceramic plate) was mechanically polished using water-resistant abrasive paper and diamond abrasive grains. Then, colloidal silica solution was used for fine polishing. Next, etching was performed, and the rolling surface (the observation surface) was observed with an optical microscope. According to the cutting method of JIS H 0501, five line segments of a specified length were drawn at specified intervals in the longitudinal and transverse directions. The number of grains that were completely cut was counted, and the average value of their cutting lengths was taken as the average crystal grain size. When the average crystal grain size was 200 μm or less, it was designated as "A" (excellent). When the average crystal grain size exceeded 200 μm and was 300 μm or less, it was designated as "B" (good). When the average crystal grain size exceeded 300 μm and was 500 μm or less, it was designated as "C" (fair). When the average crystal grain size exceeded 500 μm, it was designated as "D" (poor).

[0239] (Particle size deviation after pressure heat treatment)

[0240] As described above, within the range of 40 mm × 40 mm of the test piece subjected to pressure heat treatment, the average value of the major axis and minor axis of the coarsest grain other than twins was taken as the maximum crystal grain size d max . Here, the maximum value of the length of the line segment cut by the grain boundary among the line segments drawn on the coarsest grain was taken as the major axis. And the maximum value of the length of the line segment cut by the grain boundary among the line segments perpendicular to the major axis was taken as the minor axis. The ratio d max of this maximum crystal grain size d ave to the above-mentioned average crystal grain size d max / d ave being 15 or less was evaluated as "B" (good), and when d max / d ave exceeded 15 and was 20 or less, it was evaluated as "C" (fair), and when d max / d ave exceeded 20, it was evaluated as "D" (poor).

[0241]

[0242]

[0243]

[0244]

[0245]

[0246]

[0247] In Comparative Example 1, the average crystal grain size was small, being 8 μm, and the average value of LOS was 2.10°. After pressure heat treatment, the crystal grains coarsened and the particle size deviation also increased.

[0248] In Comparative Example 2, the average value of LOS was 2.30°. After pressure heat treatment, the crystal grains coarsened and the particle size deviation also increased.

[0249] In Comparative Example 3, the average value of LOS was set to 2.16°. The particle size deviation after pressure heat treatment increased.

[0250] In contrast, in Examples 1 to 27 of the present invention, the average crystal grain size was 10 μm or more, and the average value of LOS was set to 2.00° or less. After pressure heat treatment, the average crystal grain size became smaller and the particle size deviation also became smaller.

[0251] Based on the above, it was confirmed that according to the examples of the present invention, it was possible to provide a pure copper material that could suppress the coarsening and non-uniformity of crystal grains even after pressure heat treatment.

[0252] Industrial Applicability

[0253] The pure copper material of the present embodiment is preferably applicable to electrical / electronic components such as heat sinks or thick copper circuits.

[0254] Symbol Explanation

[0255] 1 Electronic device

[0256] 3 Electronic component

[0257] 10 Insulating substrate

[0258] 11 Ceramic substrate

[0259] 12 Circuit layer

[0260] 13 Metal layer

Claims

1. A pure copper material, characterized in that, the content of Cu is in the range of 99.9% by mass or more and 99.999% by mass or less, the average crystal grain size in the rolling surface is 10 μm or more, Measure an area of 1 mm or more at a measurement interval of 1 μm step by the EBSD method, exclude measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the average value of the local orientation distribution LOS is 2.00° or less when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary. 2 The above measurement area, excluding measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the average value of the local orientation distribution LOS is 2.00° or less when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary.

2. The pure copper material according to claim 1, characterized in that, Measure 1 mm at a measurement interval of 1 μm step by EBSD method 2 For the measurement area of 1 mm or more, excluding the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, the average value of the grain orientation spread GOS is 2.00° or less when the boundary with an orientation difference of 5° or more between adjacent pixels is regarded as a grain boundary.

3. The pure copper material according to claim 1, characterized in that, Measured at a step of 1 μm intervals by the EBSD method for a measurement area of 1 mm 2 or more, excluding measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM, and the standard deviation value of the kernel average misorientation KAM value is 0.75° or less when boundaries with an orientation difference of 5° or more between adjacent pixels are regarded as grain boundaries.

4. The pure copper material according to claim 1, characterized in that, The measurement area of 1 mm or more was measured at a step of 1 μm intervals by the EBSD method, and the measurement points with a CI value of 0.1 or less analyzed by the data analysis software OIM were excluded. When the boundary with an orientation difference of 5° or more between adjacent pixels was regarded as a grain boundary, the average value of the geometrically necessary dislocations GND was 5.0×10 2 or less. 14 m -2 ​ 5. The pure copper material according to claim 1, characterized in that, it contains one or more additive elements selected from Ca, Sr, and Ba with a total amount of 300 mass ppm or less.

6. The pure copper material according to claim 5, characterized in that, A compound containing at least one of the added element and Cu, the number density of the compound being 1×10 -4 pieces / μm 2 or more.

7. The pure copper material according to claim 6, characterized in that, The compound comprises one or more selected from Cu 5 Ca, Cu 5 Sr and Cu 13 Ba.

8. The pure copper material according to claim 1, characterized in that, it contains one or more of S, Se, and Te with a total amount of 10.0 mass ppm or less.

9. The pure copper material according to claim 1, characterized in that, the content of O is 100 mass ppm or less.

10. The pure copper material according to claim 1, characterized in that, the content of P is in the range of 0.01 mass ppm or more and 3.00 mass ppm or less.

11. The pure copper material according to claim 1, characterized in that, the mass ratio A / B of the total content A of Ca, Sr, and Ba to the total content B of P, S, Se, Te, and O exceeds 1.

0.

12. The pure copper material according to claim 1, characterized in that, it contains one or more of Ag, Fe, and Pb with a total amount of 50.0 mass ppm or less.

13. The pure copper material according to claim 1, characterized in that, it contains Mg in an amount of 100 mass ppm or less.

14. An insulating substrate, characterized in that, it includes a ceramic substrate and a copper plate joined to one surface of the ceramic substrate, and the copper plate is made of the pure copper material according to any one of claims 1 to 13.

15. An electronic device, characterized in that, it has the insulating substrate according to claim 14 and electronic components mounted on the insulating substrate.

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