WO2020203071A1 - Copper material and heat-dissipating member - Google Patents

Abstract

Provided are: a copper material which can be prevented from the growth and non-uniformization of crystal grains even after heating; and a heat-dissipating member which comprises the copper material. The copper material has a composition containing Ca at a content of 3 to 400 massppm inclusive and a remainder made up by Cu and unavoidable impurities, wherein, when the content of Ca is defined as X (massppm) and the total content of O, S, Se and Te that are contained as the unavoidable impurities is defined as Y (massppm), the requirement represented by the formula: X/Y > 2 is satisfied, the average crystal grain diameter is 200 μm or less when the copper material is subjected to a heating treatment of retaining at 800ºC for 1 hour, and the area ratio of crystal grains each having a grain diameter of 50 to 300 μm inclusive is 60% or more.

Description

Copper material and heat dissipation member

The present invention relates to a copper material and a heat-dissipating member suitable for electric / electronic parts such as a heat sink and a thick copper circuit, and more particularly to a copper material and a heat-dissipating member in which coarsening of crystal grains during heating is suppressed.
The present application claims priority based on Japanese Patent Application No. 2019-068349 filed in Japan on March 29, 2019, the contents of which are incorporated herein by reference.

Conventionally, highly conductive copper or copper alloy has been used for electric / electronic parts such as heat sinks and thick copper circuits.
Recently, as the current of electronic devices and electrical devices has increased, the size of electrical and electronic components used in these electronic devices and electrical devices has increased due to the reduction of current density and the diffusion of heat due to Joule heat generation. The wall is thickened.

Here, in the semiconductor device, for example, an insulating circuit board in which a copper material is bonded to a ceramic substrate to form the above-mentioned heat sink or thick copper circuit is used.
When joining a ceramic substrate and a copper plate, the joining temperature is often set to 800 ° C. or higher, and there is a risk that the crystal grains of the copper material constituting the heat sink or the thick copper circuit may become coarse at the time of joining. In particular, in a copper material made of pure copper having particularly excellent conductivity and heat dissipation, crystal grains tend to become coarse.
When the crystal grains become coarse in the heat sink or the thick copper circuit after bonding, the crystal grains become coarse, which may cause a problem in appearance.

Therefore, for example, Patent Document 1 proposes a copper material for the purpose of suppressing the growth of crystal grains when heated to a high temperature.
In Patent Document 1, it is described that by containing 0.0006 to 0.0015 wt% of S, it is possible to adjust the crystal grains to a certain size even if the heat treatment is performed at a recrystallization temperature or higher.

Japanese Patent Application Laid-Open No. 06-002058

By the way, in Patent Document 1, the coarsening of crystal grains is suppressed by specifying the content of S, but even if the content of S is simply specified, a sufficient effect of suppressing the coarsening of crystal grains can be obtained. I couldn't. In addition, after heating, the crystal grains may be locally coarsened and the crystal structure may become non-uniform.
Further, when the S content is increased in order to suppress the coarsening of crystal grains, there is a problem that the hot workability is greatly lowered and the production yield of the copper material is greatly lowered. there were.

The present invention has been made in view of the above-mentioned circumstances, and provides a copper material capable of suppressing coarsening and non-uniformity of crystal grains even after heating, and a heat radiating member made of the copper material. The purpose is to do.

As a result of diligent studies by the present inventors in order to solve this problem, the following findings were obtained.
When the copper material is plastically processed and then heated, the strain is released by the primary recrystallization that occurs on the low temperature side to form a uniform structure, and some of the crystal grains are coarse due to the secondary recrystallization that occurs on the high temperature side (for example, 800 ° C or higher). It becomes a non-uniform structure. Therefore, by suppressing the secondary recrystallization on the high temperature side, it is possible to suppress the coarsening and non-uniformity of the crystal grains.
Then, in the copper material to which an appropriate amount of Ca is added, compounds (hereinafter referred to as Ca-based compounds) are produced with S, Se, and Te containing Ca as unavoidable impurities, and a part of the Ca-based compounds is 800 ° C. or higher. Decomposition at temperature and solid solution of Ca and S, Se, Te in the parent phase makes it possible to suppress the growth of crystal grains by these Ca, S, Se, and Te.

The present invention has been made based on the above findings, and the copper material of the present invention has a composition in which the Ca content is in the range of 3 mass ppm or more and 400 mass ppm or less, and the balance is Cu and unavoidable impurities. When the content of is X (massppm) and the total content of O, S, Se, and Te contained as the unavoidable impurities is Y (massppm), X / Y> 2 and 1 at 800 ° C. After the time-holding heat treatment, the average crystal grain size A is 200 μm or less, and the area ratio of crystal grains in the range of 50 μm or more and 300 μm or less is 60% or more. ..

According to the copper material having this structure, the Ca content is in the range of 3 mass ppm or more and 400 mass ppm or less. Therefore, at the time of casting, Ca reacts with S, Se, and Te contained as unavoidable impurities to form a Ca compound. Is generated. When this Ca-based compound is heated at a high temperature, it decomposes into Ca and S, Se, Te and dissolves in the parent phase, and the solid-dissolved Ca and S, Se, Te inhibit the growth of crystal grains. .. Therefore, secondary recrystallization that occurs on the high temperature side (for example, 800 ° C. or higher) can be sufficiently suppressed, and coarsening and non-uniformity of crystal grains can be suppressed even after heating.
Further, when the Ca content is X (mass ppm) and the total content of O, S, Se, and Te contained as the unavoidable impurities is Y (mass ppm), X / Y> 2 is set. Even if Ca is preferentially oxidized and consumed, Ca that reacts with S, Se, and Te can be secured, and a Ca-based compound can be sufficiently produced.
After the heat treatment held at 800 ° C. for 1 hour, the average crystal grain size A is set to 200 μm or less, and the area ratio of the crystal grains in the range of 50 μm or more and 300 μm or less is set to 60% or more. Therefore, even when heated to 800 ° C. or higher, coarsening and non-uniformity of crystal grains can be reliably suppressed.

Here, in the copper material of the present invention, the average crystal grain size after the heat treatment held at 800 ° C. for 1 hour is defined as A, and the average crystal grain size after the heat treatment held at 1000 ° C. for 1 hour is defined as A. When B is set, it is preferable that B / A ≦ 2.
In this case, the difference between the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour and the average crystal grain size A after the heat treatment held at 800 ° C. for 1 hour is small, and the mixture is heated to a high temperature. Even so, coarsening and non-uniformity of crystal grains can be sufficiently suppressed.

Further, in the copper material of the present invention, the total amount of the above-mentioned unavoidable impurities excluding the above-mentioned O, S, Se and Te is preferably 0.1 mass% or less.

The heat radiating member of the present invention is characterized by being made of the above-mentioned copper material.
According to the heat radiating member having this structure, since it is made of the above-mentioned copper material, it is possible to suppress coarsening and non-uniformity of crystal grains even when heated to a high temperature of 800 ° C. or higher at the time of joining. it can.

According to the present invention, it is possible to provide a copper material capable of suppressing coarsening and non-uniformity of crystal grains even after heating, and a heat radiating member made of this copper material.

It is a flow chart of the manufacturing method of the copper material which is this embodiment.

The copper material according to the embodiment of the present invention will be described below.
The copper material of the present embodiment is used as a material for electric / electronic parts such as a heat sink and a thick copper circuit, and is used by being bonded to a ceramic substrate, for example, when molding the above-mentioned electric / electronic parts. It is a thing.

The copper material of the present embodiment has a composition in which the Ca content is in the range of 3 mass ppm or more and 400 mass ppm or less, and the balance is Cu and unavoidable impurities, and the Ca content is X (mass ppm) and is included as unavoidable impurities. When the total content of O, S, Se, and Te is Y (mass ppm), the relationship of X / Y> 2 is satisfied.

In the copper material of the present embodiment, after the heat treatment held at 800 ° C. for 1 hour, the average crystal grain size A is set to 200 μm or less, and the crystal grains in the range of 50 μm or more and 300 μm or less. The area ratio of is 60% or more.
Further, in the copper material of the present embodiment, the average crystal grain size after the heat treatment held at 800 ° C. for 1 hour is A, and the average crystal grain size after the heat treatment held at 1000 ° C. for 1 hour is set. When B is set, it is preferable that B / A ≦ 2.
Further, in the copper material of the present embodiment, the total amount of unavoidable impurities excluding O, S, Se and Te is 0.1 mass% or less.

Here, in the copper material of the present embodiment, the reason why the component composition and the crystal grain size after the heat treatment are defined as described above will be described below.

(Ca content: 3 massppm or more and 400 massppm or less)
Ca produces S, Se, Te and Ca compounds contained as unavoidable impurities. Since a part of this compound is decomposed at a high temperature and Ca and S, Se, Te are solid-solved, it is possible to suppress the growth of crystal grains by the solid-dissolved Ca and S, Se, Te. ..
Here, if the Ca content is less than 3 mass ppm, there is a possibility that the Ca-based compound cannot be sufficiently produced. On the other hand, when the Ca content exceeds 400 mass ppm, a coarse Ca-based compound may be produced and the processability may be significantly reduced.
Therefore, in the present embodiment, the Ca content is set within the range of 3 mass ppm or more and 400 mass ppm or less.
The lower limit of the Ca content is preferably 3.5 mass ppm or more, and more preferably 4 mass ppm or more. The upper limit of the Ca content is preferably 350 mass ppm or less, and more preferably 300 mass ppm or less. More preferably, it is 100 mass ppm or less.

(Ratio of Ca content X to total content Y of O, S, Se, Te: X / Y> 2)
The above-mentioned Ca has higher reactivity with O than S, Se, and Te, and is preferentially oxidized to consume Ca.
Therefore, by making the ratio X / Y of the Ca content X to the total content Y of O, S, Se, and Te contained as unavoidable impurities larger than 2, Ca remains after being consumed by oxidation. A sufficient amount of Ca is secured, and when S, Se, Te react with the residual Ca, a Ca-based compound can be sufficiently produced.
The ratio X / Y of the Ca content X and the total content Y of O, S, Se, and Te is preferably 2.2 or more, and more preferably 2.5 or more. The upper limit of X / Y is not particularly limited, but is substantially 50 or less.

(Other unavoidable impurities)
Other unavoidable impurities other than the above-mentioned elements include Ag, B, Bi, Sc, rare earth elements (excluding Sc and Y), V, Nb, Ta, Cr, Mg, Sr, Ba, Ti and Zr. , Hf, Y, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pb, Pd, Pt, Au, Zn, Cd, Hg, Al, Ga, In, Ge, Sn , As, Sb, Tl, Be, N, C, Si, Li, H and the like. Since these unavoidable impurities may lower the thermal conductivity, the total amount is preferably 0.1 mass% or less.

(Average crystal grain size A after heat treatment held at 800 ° C. for 1 hour: 200 μm or less)
In the copper material of the present embodiment, when the crystal grain size after the heat treatment held at 800 ° C. for 1 hour is 200 μm or less, the crystal grains are coarsened even when heated to 800 ° C. or higher. Can be reliably suppressed.
The average crystal grain size after the heat treatment held at 800 ° C. for 1 hour is preferably 180 μm or less, and more preferably 150 μm or less. Further, the lower limit of the average crystal grain size after the heat treatment held at 800 ° C. for 1 hour is not particularly limited, but is substantially 50 μm or more.

(Area ratio of crystal grains in the range of 50 μm or more and 300 μm or less after heat treatment held at 800 ° C. for 1 hour: 60% or more)
In the copper material of the present embodiment, when the area ratio of the crystal grains in the range of 50 μm or more and 300 μm or less is 60% or more after the heat treatment held at 800 ° C. for 1 hour, the copper material is heated to 800 ° C. or more. Even if it is, it is possible to surely suppress the non-uniformity of the crystal grains.
Further, the minimum particle size in the range of the particle size within 60% or more of the area ratio of the crystal after the heat treatment held at 800 ° C. for 1 hour is preferably 75 μm or more, and more preferably 100 μm or more.

(Ratio of average crystal grain size A after heat treatment held at 800 ° C. for 1 hour and average crystal grain size B after heat treatment held at 1000 ° C. for 1 hour: B / A ≦ 2)
In the copper material of the present embodiment, the ratio B of the average crystal grain size A after the heat treatment held at 800 ° C. for 1 hour and the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour. When / A is 2 or less, the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour and the average crystal grain size A after the heat treatment held at 800 ° C. for 1 hour. The difference between the two is small, and even when heated to a high temperature, coarsening and non-uniformity of crystal grains can be sufficiently suppressed.
The ratio B / A of the average crystal grain size A after the heat treatment held at 800 ° C. for 1 hour and the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour is 1.9. It is preferably less than or equal to, and more preferably 1.5 or less. Further, the lower limit of B / A is not particularly limited, but is substantially 0.8 or more.

Next, the method for manufacturing the copper material according to the present embodiment having such a configuration will be described with reference to the flow chart shown in FIG.

(Melting / Casting Step S01)
First, the copper raw material is melted to produce a molten copper. As the copper raw material, for example, it is preferable to use oxygen-free copper having a purity of 99.99 mass% or more and oxygen-free copper having a purity of 99.999 mass% or more.
Next, Ca is added to the obtained molten copper so as to have a predetermined concentration to prepare the components. When adding Ca, a simple substance of Ca, a Cu—Ca mother alloy, or the like can be used. Further, also when producing a Cu—Ca mother alloy, it is preferable to use oxygen-free copper having a purity of 99.99 mass% or more and oxygen-free copper having a purity of 99.999 mass% or more.
Then, a molten copper whose composition has been adjusted is injected into a mold to produce an ingot. In consideration of mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.
In the process of this melting / casting step S01, a part of the added Ca reacts with S, Se, and Te contained as unavoidable impurities to generate a Ca-based compound.

(Hot working process S02)
Next, hot working is performed to make the structure uniform. The heating in this hot working step is preferably carried out in a non-oxidizing or reducing atmosphere.
The hot working temperature is not particularly limited, but is preferably in the range of 500 ° C. or higher and 1000 ° C. or lower. It is desirable that the hot working start temperature be 700 ° C. or higher in consideration of machining heat generation in order to uniformly generate Ca-based compounds in a later step. More preferably, it is 750 ° C. or higher.
Further, the total processing rate of hot working is preferably 40% or more, more preferably 60% or more, and even more preferably 70% or more.
The hot working end temperature is preferably less than 700 ° C. More preferably, it is 650 ° C. or lower.
Further, the cooling method after hot working is not particularly limited, but air cooling or water cooling is preferable.
Further, the processing method in the hot processing step S02 is not particularly limited, and for example, rolling, extrusion, groove rolling, forging, pressing, or the like can be adopted. When the final shape is a plate or strip, rolling is preferably adopted, when the final shape is a line or rod, extrusion or groove rolling is preferably adopted, and when the final shape is a bulk material, forging or forging or It is preferable to use a press.

(Cold working process S03)
Next, the copper material after the hot working step S02 is cold-worked to be processed into a predetermined shape. The temperature condition in this cold working step S03 is not particularly limited, but it is preferably performed in the range of −200 ° C. or higher and 200 ° C. or lower. Further, the processing ratio in the cold processing step S03 is appropriately selected so as to approximate the final shape, but it is preferably 30% or more in order to improve the productivity.
Further, the processing method in the cold processing step S03 is not particularly limited, and for example, rolling, extrusion, groove rolling, forging, pressing, or the like can be adopted. When the final shape is a plate or strip, rolling is preferably adopted, when the final shape is a line or rod, extrusion or groove rolling is preferably adopted, and when the final shape is a bulk material, forging or forging or It is preferable to use a press.

(Recrystallization Heat Treatment Step S04)
Next, the copper material after the cold working step S03 is heat-treated for the purpose of recrystallization. Here, if the recrystallized grains after the recrystallization heat treatment step S04 are fine, the growth of the crystal grains and the non-uniformity of the structure may be promoted when the recrystallized grains are subsequently heated to 800 ° C. or higher. Therefore, it is preferable that the average crystal grain size of the recrystallized grains after the recrystallization heat treatment step S04 is 10 μm or more. It is more preferably 15 μm or more, still more preferably 20 μm or more. The upper limit of the particle size at the time of recrystallization is not particularly defined, but is substantially 200 μm or less.
The heat treatment conditions of the recrystallization heat treatment step S04 are not particularly limited, but it is preferable to keep the heat treatment temperature in the range of 200 ° C. or higher and 850 ° C. or lower in the range of 1 second or more and 24 hours or less. In this case, it is preferable to perform a short-time heat treatment at a high temperature and a long-time heat treatment at a low temperature so that the particle size after recrystallization falls within the above range. The cooling rate is not particularly specified, but when the heat treatment is performed at a temperature of 800 ° C. or higher, the cooling rate may be 10 ° C./sec or lower at a temperature of 500 ° C. or higher and lower than 800 ° C., and preferably 5 ° C./sec. Hereinafter, it may be more preferably 1 ° C./sec or less.
Further, in order to make the recrystallization structure uniform, the cold processing step S03 and the recrystallization heat treatment step S04 may be repeated twice or more.

(Taking process S05)
Next, in order to adjust the material strength, the copper material after the recrystallization heat treatment step S04 may be tempered. If it is not necessary to increase the material strength, the tempering process may not be performed.
The processing rate of the tempering process is not particularly limited, but it is preferable to carry out the tempering process within a range of more than 0% and 50% or less in order to adjust the material strength. Further, if necessary, further heat treatment may be performed after the tempering process in order to remove the residual strain.

In this way, the copper material according to the present embodiment is produced.

In the copper material of the present embodiment having the above configuration, the Ca content is in the range of 3 mass ppm or more and 400 mass ppm or less, so that it is inevitable with Ca during casting, hot working, and recrystallization heat treatment. Ca-based compounds are produced by reacting with S, Se, and Te contained as impurities. When this Ca-based compound is heated to 800 ° C. or higher, it decomposes into Ca and S, Se, Te and dissolves in solid solution, and the solid-dissolved Ca and S, Se, Te inhibit the growth of crystal grains. Therefore, even when the copper material is heated to, for example, 800 ° C. or higher, secondary recrystallization can be sufficiently suppressed, and coarsening and non-uniformity of crystal grains can be suppressed even after heating.

Further, in the copper material of the present embodiment, the ratio X / Y of the Ca content X (mass ppm) and the total content Y (mass ppm) of O, S, Se, and Te contained as unavoidable impurities is 2 or more. Is also set to a large value, so even if Ca preferentially reacts with oxygen and is consumed, the amount of residual Ca that reacts with S, Se, and Te can be secured, and a Ca-based compound can be sufficiently produced. Can be done.

Further, in the copper material of the present embodiment, the average crystal grain size A is 200 μm or less after the heat treatment held at 800 ° C. for 1 hour. Therefore, when the copper material is heated to 800 ° C. or higher. Even so, it is possible to surely suppress the coarsening of crystal grains.
Further, in the copper material of the present embodiment, after the heat treatment held at 800 ° C. for 1 hour, the area ratio of the crystal grains in the range of 50 μm or more and 300 μm or less is set to 60% or more. Even when the material is heated to 800 ° C. or higher, non-uniformity of crystal grains can be reliably suppressed.

Further, in the copper material of the present embodiment, the average crystal grain size A after the heat treatment held at 800 ° C. for 1 hour and the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour When the ratio B / A is 2 or less, the average crystal grain size B after the heat treatment held at 1000 ° C. for 1 hour and the average crystal grain size after the heat treatment held at 800 ° C. for 1 hour The difference from the diameter A is small, and even if it is heated to a high temperature of 1000 ° C. or higher, coarsening and non-uniformity of crystal grains can be sufficiently suppressed.

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 appropriately changed without departing from the technical idea of the present invention.
For example, in the above-described embodiment, an example of a method for producing a copper material has been described, but the method for producing a copper material is not limited to the one described in the embodiment, and an existing production method is appropriately selected. It may be manufactured.

The results of the confirmation experiment conducted to confirm the effect of the present invention will be described below.
A copper raw material made of oxygen-free copper having a purity of 99.99 mass% or more was charged into a high-purity graphite crucible and melted at high frequency in an atmosphere furnace having an Ar gas atmosphere. Cu-1 mass% Ca mother alloy was added to the obtained molten copper to prepare the component composition shown in Table 1.
The obtained molten copper was poured into a mold to produce an ingot. The size of the ingot was about 25 mm in thickness × about 70 mm in width × about 160 to 190 mm in length.

The obtained ingot was heated at 800 ° C. for 1 hour in an Ar gas atmosphere and hot-rolled to a thickness of 15 mm.
The copper material after hot rolling was cut and surface grinding was performed to remove the oxide film on the surface. At this time, the thickness of the copper material to be subjected to cold rolling was adjusted so that the final thickness was 0.8 mm in consideration of the rolling ratio of the subsequent cold rolling and temper rolling.

The copper material whose thickness was adjusted as described above was cold-rolled under the condition of a processing rate of 90%.
Next, the copper material after cold rolling was subjected to recrystallization heat treatment under the condition of holding at 600 to 850 ° C. for 5 seconds.
Then, the copper material after the recrystallization heat treatment was temper-rolled under the condition of a processing rate of 5 to 50% to produce a copper material having a thickness of 0.8 mm and a width of 60 mm.

Then, the following items were evaluated. The evaluation results are shown in Table 2.

(Copper composition analysis)
A measurement sample was collected from the obtained copper material, and the composition was analyzed by an ICP-MS analyzer (7500CX manufactured by Agilent). As a result, it was confirmed that the composition was shown in Table 1.

(Average crystal grain size A after heat treatment at 800 ° C. for 1 h)
The obtained copper material was heat-treated at 800 ° C. for 1 hour. A 50 mm × 50 mm sample was cut out from this test piece, mechanically polished with water-resistant abrasive paper and diamond abrasive grains, and then finish-polished with a colloidal silica solution.
Adjacent measurements at a measurement area of 1000 μm ² at a measurement interval of 5 μm using an EBSD measuring device (QUANTA 450 EFG, EDAX / TSL AMETEK9424) and analysis software (TSL OIM Analysis 7 × 64). A grain boundary map was created with the grain boundaries between the measurement points where the orientation difference between the points is 15 ° or more. When creating the grain boundary map, the measurement points where the CI value was 0.1 or less were excluded.
In accordance with the cutting method of JIS H 0501, 5 line segments of a predetermined length are drawn vertically and horizontally on the above-mentioned crystal grain boundary map, and the number of crystal grains completely cut by the line segments is counted. , The average value of the cutting length was taken as the average crystal grain size.

(Area ratio of crystal grains having a particle size of 50 μm or more and 300 μm or less after heat treatment at 800 ° C. for 1 h)
The crystal grain size of each crystal grain was obtained from the grain boundary map created at the time of the above measurement of the crystal grain size A using analysis software (OIM Analysis 7 × 64 manufactured by TSL), and all the crystal grains were found from the Area Fraction. From the total area, the area ratio of the crystal grains having a particle size of 50 μm or more and 300 μm or less was calculated.

(Average crystal grain size B after heat treatment at 1000 ° C. for 1 h)
A test piece was collected from the obtained copper material and heat-treated at 1000 ° C. for 1 hour. A 50 mm × 50 mm sample was cut out from this test piece, and the average crystal grain size B after heat treatment at 1000 ° C. for 1 h was obtained by the same procedure as the above-mentioned “Average crystal grain size A after heat treatment at 800 ° C. for 1 h”. Calculated.

In Comparative Example 1, Ca was not added, and the average crystal grain size A after heat treatment at 800 ° C. for 1 h was 215 μm, and the average crystal grain size B after heat treatment at 1000 ° C. for 1 h was 478 μm. The grains became coarse. In addition, the area ratio of crystals having a particle size of 50 μm or more and 300 μm or less after heat treatment at 800 ° C. for 1 h was as low as 55%, and the crystal grains after heat treatment were non-uniform.

In Comparative Example 2, the ratio of the Ca content X (mass ppm) to the total content Y (mass ppm) of O, S, Se, and Te contained as unavoidable impurities is 0.2, and 1 h at 800 ° C. The average crystal grain size A after the heat treatment was 204 μm, the average crystal grain size B after the heat treatment at 1000 ° C. for 1 h was 506 μm, and the crystal grains were coarsened after the heat treatment. In addition, the area ratio of crystals having a particle size of 50 μm or more and 300 μm or less after heat treatment at 800 ° C. for 1 h was as low as 49%, and the crystal grains after heat treatment were non-uniform.

In Comparative Example 3, the ratio of the Ca content X (mass ppm) to the total content Y (mass ppm) of O, S, Se, and Te contained as unavoidable impurities is 1.5, and 1 h at 800 ° C. The average crystal grain size A after the heat treatment was 233 μm, the average crystal grain size B after the heat treatment at 1000 ° C. for 1 h was 557 μm, and the crystal grains were coarsened after the heat treatment. Further, the area ratio of the crystal grains in the range of 50 μm or more and 300 μm or less after the heat treatment at 800 ° C. for 1 h was as low as 51%, and the crystal grains after the heat treatment were non-uniform.

In Comparative Example 4, the Ca content was 543 mass ppm, and cracks occurred during processing. Therefore, the subsequent evaluation was stopped. It is presumed that a coarse Ca-based compound was produced during casting.

On the other hand, the composition is such that the Ca content is in the range of 3 mass ppm or more and 400 mass ppm or less, and the balance is Cu and unavoidable impurities, and the Ca content X (mass ppm) and O, S, Se contained as unavoidable impurities. In Example 1-15 of the present invention in which the ratio X / Y to the total content Y (mass ppm) of Te is larger than 2, the average crystal grain size A after heat treatment at 800 ° C. for 1 h is 155 μm or less, at 1000 ° C. The average crystal grain size B after the heat treatment for 1 h was 183 μm or less, and the coarsening of the crystal grains after the heat treatment was suppressed. Further, the area ratio of the crystals having a particle size of 50 μm or more and 300 μm or less after the heat treatment at 800 ° C. for 1 h was 60% or more, and the crystal grains after the heat treatment were uniform.

From the above, it was confirmed that according to the example of the present invention, it is possible to provide a copper material capable of suppressing coarsening and non-uniformity of crystal grains even after heating.

Possibility of industrial use

The copper material and the heat radiating member of the present invention are preferably used for members in which it is preferable to suppress coarsening of crystal grains to prevent changes in appearance, for example, electric / electronic parts provided with a heat sink, a thick copper circuit, or the like. be able to.

Claims (4)

1. The composition is such that the Ca content is within the range of 3 mass ppm or more and 400 mass ppm or less, and the balance is Cu and unavoidable impurities.
   When the Ca content is X (mass ppm) and the total content of O, S, Se, and Te contained as the unavoidable impurities is Y (mass ppm), X / Y> 2.
   After the heat treatment held at 800 ° C. for 1 hour, the average crystal grain size is 200 μm or less, and the area ratio of the crystal grains in the range of 50 μm or more and 300 μm or less is 60% or more. Characteristic copper material.
2. B / A ≦ 2 when the average crystal grain size after the heat treatment held at 800 ° C. for 1 hour is A and the average crystal grain size after the heat treatment held at 1000 ° C. for 1 hour is B. The copper material according to claim 1, wherein the copper material is characterized by the above.
3. The copper material according to claim 1, wherein the unavoidable impurities excluding the O, S, Se, and Te are 0.1 mass% or less in total.
4. A heat radiating member made of the copper material according to any one of claims 1 to 3.

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