JP2007270269A - Copper alloy having excellent hot workability and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy for an electronic component having excellent hot workability which particularly has excellent strength and electrical conductivity without deteriorating its bending workability. <P>SOLUTION: The copper alloy having excellent hot workability has a composition comprising, by mass, 1.0 to 2.0% Ni and 0.1 to 0.5% P, and in which the ratio between the Ni content and the P content, Ni/P is 4.0 to 6.5, and also, comprising 0.005 to 0.070% B, and the balance Cu with inevitable impurities. The copper alloy may further comprise one or more kinds selected from Sn and In by 0.01 to 1.0% in total, and the number of inclusions with a major axis of 5 to 50 μm is ≤100 pieces per mm<SP>2</SP>, and also, the number of inclusions with a major axis of >50 μm is zero per mm<SP>2</SP>. In the method for producing the copper alloy, the average cooling rate in the range from 1,100°C to 950°C upon casting is preferably controlled to ≥20°C/min, and more preferably to ≥30°C/min. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a copper alloy excellent in hot workability for high-strength, high-conductivity electronic device parts, and particularly in a small and highly integrated copper alloy for semiconductor device leads and terminal connectors. The present invention relates to a copper alloy for electronic parts that is particularly excellent in strength and conductivity without deteriorating bending workability and excellent in hot workability.

Copper and copper alloys are materials that are widely used for electronic parts such as connectors and lead terminals and flexible circuit boards, and are highly functional and miniaturized due to the rapid development of IT.・ Further improvements in properties (strength, bending workability, conductivity) are required in response to thinning.
In addition, with the high integration of ICs, many semiconductor elements with high power consumption are used, and the lead frame material of semiconductor devices has a good heat dissipation (conductivity) such as Cu-Ni-Si or Cu. Precipitation alloys such as -Fe-P, Cu-Cr-Sn, and Cu-Ni-P have come to be used. The Cu—Ni—P alloy is strengthened by the fine precipitation of the Ni—P compound, but in Patent Document 1, the amount of Ni, P, and Mg components in the alloy is adjusted to reduce the strength, conductivity, and stress resistance. It has been reported that an alloy with properties is obtained.

JP 2000-273562 A

In general, in the casting of a copper alloy, for example, continuous or semi-continuous casting, the ingot is heat-extracted by a mold, and the inside solidifies with some time except for a few mm of the surface layer of the ingot. At this time, alloy elements contained exceeding the limit during the solidification and after the solidification cooling process are crystallized or precipitated in the crystal grain boundaries and in the crystal grains. A copper alloy containing 1.0% or more of Ni and 0.2% or more of P has the advantage of high strength and high conductivity, but at room temperature, it has a Ni-P component exceeding the solid solubility limit in the Cu matrix. Since it is contained in a large amount, when an ingot is produced, a Ni-P compound is usually crystallized or precipitated at the crystal grain boundary. And since the melting point of the Ni-P compound compound crystallized or precipitated at the grain boundary of the Cu-Ni-P alloy is lower than that of the parent phase Cu, the solidification of these copper alloys becomes uneven and internal strain occurs. However, due to the stress and external force, fracture occurs in the Ni-P-based compound portion, causing cracks in the casting and cooling stages. Moreover, since the Ni-P compound softens or becomes a liquid phase prior to the parent phase during the hot rolling, cracks are similarly generated.
However, since the composition of the Cu-Ni-P alloy of Patent Document 1 is 0.01 to 1.0% for Ni and 0.01 to 0.2% for P, the above problem was not particularly conscious.
An object of the present invention is to provide a Cu-Ni-P alloy that prevents cracking during casting, cooling, hot working heating or hot working, has excellent high temperature ductility and good hot workability. It is what.

As a result of repeated research to achieve the above object, the present inventors have identified a Cu-Ni-P alloy having excellent hot workability, excellent strength and conductivity by specifying the following configuration. It was found that it can be obtained.
In the present invention, the copper alloy contains Ni: 1.0% or more and 2.0% or less (in the present specification,% indicating the component ratio is mass%), P: 0.15% or more and 0.50% or less The content ratio of Ni and P is Ni / P: 4.0 or more and 6.5 or less, and B: 0.005% or more and 0.070% or less, and the balance is made of Cu and inevitable impurities. Copper alloy excellent in hot workability, preferably the number of inclusions having a major axis of 5 to 50 μm is 100 or less per 1 mm ² , and the number of inclusions exceeding 50 μm of major axis is 0 per 1 mm ² The present invention relates to a copper alloy and a method for producing a copper alloy having excellent hot workability, wherein a cooling rate from 1100 ° C. to 950 ° C. during casting is 20 ° C./min or more.

In the present invention, by adding a specific amount of B to a Cu-Ni-P-based alloy, crystallization or precipitation of Ni-P-based compounds at the grain boundaries is suppressed, and preferably the cooling rate during casting is controlled. This suppresses the formation of coarse Ni—P—B and P—B compounds. By adopting the above configuration, the present invention improves the hot workability by improving the high temperature brittleness of the grain boundaries.
The copper alloy excellent in hot workability of the present invention has an excellent effect for high-strength and high-conductivity electronic equipment.

Next, the reason for limiting the numerical range of the component composition of the copper alloy in the present invention will be described together with its action.
[Ni content]
Ni has the effect of ensuring the strength and heat resistance of the alloy and precipitates a Ni—P compound with P, which will be described later, thereby contributing to an increase in the strength of the alloy. However, if the content is less than 1.0%, the desired strength cannot be obtained. On the other hand, if Ni exceeds 2.0%, the hot workability decreases and the bending workability of the product and The decrease in conductivity becomes remarkable. Furthermore, the area ratio of Ni—P-based precipitates having a large major axis is increased, which is not preferable. When the total content of Ni and P (Ni + P) exceeds 2.5%, the crystallization amount of coarse particles increases, and the precipitation due to aging treatment becomes more prominent, resulting in the precipitation of fine Ni-P having a size of 50 nm or less. It becomes difficult to control. Therefore, the Ni content of the alloy of the present invention is 1.0% to 2.0%, preferably 1.1 to 1.8%.

[P amount]
P precipitates a compound with Ni to improve the strength and heat resistance of the alloy. If the P content is less than 0.15%, precipitation of the compound is insufficient, so that the desired strength cannot be obtained. On the other hand, if the P content exceeds 0.5%, the hot workability is lowered and the conductivity is significantly lowered. Furthermore, the area ratio of Ni—P-based precipitates having a large major axis is increased, which is not preferable. Therefore, the P content of the alloy of the present invention is 0.15% to 0.5%, preferably 0.2 to 0.4%.

[Ni / P ratio]
If the Ni / P content ratio Ni / P deviates from the appropriate stoichiometric composition ratio of the Ni-P compound even if the Ni and P contents are within the above-mentioned limited range, that is, less than 4.0 In this case, when P exceeds 6.5, the amount of Ni dissolved increases, which is not preferable because the decrease in conductivity is remarkable. Therefore, the Ni / P ratio of the alloy of the present invention is 4.0 or more and 6.5 or less, preferably 4.5 to 6.0.

[Size and area ratio of Ni-P-based precipitates]
When the major axis of the Ni-P-based precipitate is a (nm) and the minor axis is b (nm), the precipitate with a before the final cold rolling of less than 20 nm undergoes rolling with a work strain η = 2 or more. Then, the precipitate is re-dissolved in copper, which lowers the conductivity, which is not preferable. On the other hand, a precipitate having a of 20 nm or more before the final cold rolling is not easily re-dissolved even in a rolling process having a working strain η = 2 or more, and exists as a precipitate having a thickness of 10 nm or more. Precipitates of 20 nm or more have little change in size before and after rolling. Particularly, precipitates with a major axis a before rolling exceeding 50 nm maintain a major axis exceeding 50 nm after rolling, and the dispersion interval of the precipitates in the alloy is large. Therefore, the precipitation strengthening effect cannot be obtained.
The major axis a and the minor axis b are obtained by cutting the alloy strip before the final cold rolling in a direction perpendicular to the thickness parallel to the rolling direction, and measuring all the precipitates having a major axis a of 5 nm or more using an image analyzer. It is the average value of each major axis and minor axis of all the precipitates. Further, the processing strain eta, the plate thickness before rolling t _0, when the plate thickness after rolling was t, is expressed by _{η = ln (t 0 / t} ).
From the above, the major axis “a” of the Ni—P-based precipitate before the final cold rolling of the alloy of the present invention is preferably 20 nm to 50 nm.
Moreover, when the aspect ratio of the precipitate is expressed by a / b, when a / b exceeds 5, when the rolling process is performed with η = 2 or more, the precipitate is re-dissolved in the copper, and the conductivity is reduced. It will decrease. Therefore, the aspect ratio a / b of the precipitate is preferably 1 to 5, more preferably 1 to 3.
In order to prevent a decrease in strength and electrical conductivity, a after the final cold rolling is preferably 10 nm to 50 nm and a / b is 1 to 5.

However, since it is difficult to make all the precipitates within the preferable ranges of a and a / b, the ratio of the precipitates within the ranges of a and a / b to the total precipitates is important. Therefore, when the ratio of the total area of precipitates in the preferable range of a and a / b to the total area of all precipitates in the alloy is defined as area ratio C, the area ratio C of the present invention is preferably 80% or more. It is.
The case where the area ratio C is less than 80% is a case where there are many precipitates in which a exceeds 50 nm or precipitates less than 20 nm. For example, there are many Ni-P-based particles (crystallized material) of 1000 nm or more in which precipitates with a exceeding 50 nm or crystallized products generated during melt casting remain without being dissolved by hot rolling or solution treatment. When present, since the number of fine precipitates having a size of 20 to 50 nm that contributes to the strength improvement is small and the dispersion interval is large, the desired strength by work hardening in the rolling process cannot be obtained. On the other hand, since the precipitate with a of less than 20 nm is re-dissolved by processing in the rolling process, the desired strength cannot be obtained.

[B amount]
B suppresses the crystallization or precipitation of the Ni-P-based compound at the grain boundary during the solidification of the Cu-Ni-P-based alloy, the cooling process after the solidification and the heating during the hot working, and the hot working of the alloy. Improve sexiness. However, if the content is less than 0.005%, the effect of improving hot workability cannot be obtained. On the other hand, if the content of B exceeds 0.070%, Ni-P-B, BP, etc. This compound occurs as an inclusion during dissolution or coagulation. Since these B-containing compounds are usually crystallized or precipitated with agglomeration and coarsening at the grain boundaries and do not dissolve in the Cu matrix by solution treatment, they are precipitated by aging treatment. The compound is reduced and the strength of the alloy is reduced. Further, compounds such as Ni-P-B and BP remain in the product as inclusions having a major axis of 5 μm or more, and surface defects of the product, starting points of cracks during bending, and defects during plating processing. Since it becomes a starting point, it is not preferable. Therefore, the B content of the alloy of the present invention is 0.005% to 0.070% or less, preferably 0.007% to 0.060%.

[Inclusion]
The “inclusion” of the present invention is mainly composed of a Ni—P—B compound, a BP compound, or the like crystallized or precipitated in a crystal grain boundary and / or crystal grain in a Cu—Ni—P-based alloy. And does not contain a fine Ni-P compound that crystallizes or precipitates in the crystal grains. The major axis of inclusions means the average major axis of inclusions having a size of 5 μm or more in the rolling parallel section.
If inclusions with a major axis of more than 50 μm are present, they become the starting point of cracking during bending and deteriorate the bending workability of the product. Therefore, in the copper alloy of the present invention, the number of inclusions having a major axis exceeding 50 μm is preferably 0 per 1 mm ² . Further, when inclusions having a major axis of 5 to 50 μm are present, the amount of B contained in the inclusions increases, and the effect of suppressing crystallization of Ni—P compounds, which is the purpose of addition of B, to the crystal grain boundaries can be obtained. Disappear. Therefore, in the copper alloy of the present invention, the number of inclusions having a major axis of 5 to 50 μm is preferably 100 or less, more preferably 50 or less per mm ² .

[Sn, In amount]
Both the Sn and In contents have the effect of improving the strength mainly by solid solution strengthening without greatly reducing the conductivity of the alloy. Accordingly, if necessary, one or more of these metals are added. If the total content is less than 0.01%, the effect of improving the strength by solid solution strengthening cannot be obtained, while the total amount is 1.0. When adding more than%, the electrical conductivity and bending workability of the alloy are significantly reduced. For this reason, the amount of Sn and In added individually or in combination of two or more types is 0.01% to 1.0%, preferably 0.05% to 0.8% in total. In the present invention, these elements are intentionally added elements and are not regarded as inevitable impurities.
[O amount]
O easily reacts with B in the alloy, and if O exists in an oxide state in the alloy, the B addition effect cannot be obtained. Therefore, the O content of the alloy of the present invention is 0.0050% or less, preferably 0.0030% or less.

[Tensile strength and conductivity]
The copper alloy of the present invention is excellent in hot workability and further has excellent conductivity, tensile strength and bending workability. The tensile strength of the copper alloy of the present invention is preferably 700 MPa or more, more preferably 750 MPa or more, and the upper limit is usually about 950 MPa. Further, the conductivity is preferably 40% IACS or more, more preferably 40% IACS or more, and the upper limit is usually about 65% IACS.

[Cooling rate during solidification and size of inclusions]
The Cu—Ni—P alloy satisfying the above-mentioned requirements of the present invention is generally used by those skilled in the art for ingot casting, hot rolling, solution treatment, intermediate cold rolling, aging treatment, final cold rolling, strain. In the annealing and the like, it can be manufactured by appropriately selecting the heating temperature, time, cooling rate, rolling degree, and the like. The solidification speed in continuous or semi-continuous casting that is usually performed differs depending on the equipment and method used in the solidification stage, and in the case of a pouring type that does not employ cooling uniformization means, there is a difference between the outside and inside of the ingot. . For example, in the case of a pouring type in which molten copper is poured into an iron mold (φ700 × h1500 mm) and solidified, the cooling rate from 1100 ° C. to 950 ° C. is about 1 ° C./min.
The solidification temperature range at the time of casting of the copper alloy of the present invention is preferably 1100 ° C. to 950 ° C. If the cooling rate in this cooling temperature range is slow, the Ni—PB system and / or the PB system compound is solidified. It is easy to produce coarsely at a stage, and there is a possibility that improvement of hot ductility by addition of B is not recognized.

The following correlation was recognized between the number of inclusions mainly composed of the Ni—P—B and / or P—B compounds and the hot ductility. In the measurement results of the inclusions in the sample obtained by heating an ingot at 1100 ° C. to 950 ° C. at a cooling rate of less than 20 ° C./min in the casting and solidification stage to 850 ° C. for 1 hour, When the number of inclusions of 50 μm is 100 or more per 1 mm ² , or when the number of inclusions exceeding 50 μm in the major axis is 1 or more per 1 mm ² , hot rolling at 850 ° C. even for an alloy to which a predetermined amount of B is added Cracking occurred. Accordingly, the cooling rate from 1100 ° C. to 950 ° C. in the casting and solidification stage is preferably 20 ° C./min or more. Furthermore, in order not to deteriorate the bending workability of the alloy, the cooling rate from 1100 ° C. to 950 ° C. in the casting and solidification stage is set to suppress coarse precipitation of Ni—P—B compounds and P—B compounds. 30 ° C./min or more is preferable. Note that a cooling rate exceeding 1500 ° C./min is not preferable because the supply of molten copper to the solidification shrinkage portion is not in time and defects due to shrinkage increase.

Invention Example and Comparative Examples 1-18
Sample preparation (a):
Electrical copper or oxygen-free copper as the main raw material, nickel (Ni), 15% P-Cu master alloy (P), 2% B-Cu master alloy (B), tin (Sn), indium (In) as auxiliary raw materials And melted in a high-frequency melting furnace in a vacuum or in an argon atmosphere, and cast into a 45 × 45 × 90 mm ingot using a cast iron material. Ingots were subjected to a hot rolling test, and ingots that were not cracked by hot rolling were subjected to hot rolling and solution treatment, aging treatment, intermediate cold rolling, aging treatment, final cold rolling, and strain relief annealing. It implemented in order and was set as the flat plate of thickness 0.15mm. Various test pieces of the obtained plate material were collected and tested, and “strength” and “conductivity” were evaluated.

Ingot hot workability evaluation (a):
“Hot workability” was evaluated by hot rolling. That is, the ingot was cut into 45 × 45 × 25 mm, heated to 850 ° C. for 1 hour, and then subjected to a hot rolling test in three passes from a thickness of 25 mm to 5 mm. The case where cracks were visually observed on the surface and edge of the sample after hot rolling was defined as “cracked”, and the case where the surface and edge were not cracked and smooth was defined as “no crack”.

Physical property evaluation of test piece (a):
About "strength", it carried out using the No. 13 B test piece by the tension test prescribed | regulated to JISZ2241, and measured the tensile strength.
“Conductivity” was measured by measuring the electrical resistance of a test piece using a four-terminal method and expressed in% IACS.

Evaluation of Ni-P-based precipitate (a);
The alloy strips before the final cold rolling were cut parallel to the rolling direction at a right angle to the thickness, and using a scanning electron microscope and a transmission electron microscope, 10 precipitates of the cross section were observed. When the size of the precipitate is 5 to 50 nm, the field of view is about 500,000 to 700,000 times (about 1.4 × 10 ^{10 to} 2.0 × 10 ¹⁰ nm ² ), and when the size is 100 to 2000 nm, the field is 50,000 times to Photographing was performed with a 100,000 × field of view (approximately 1.0 × 10 ^{13 to} 2.0 × 10 ¹³ nm ² ). Using the image of the photographed photograph, the major axis a, the minor axis b, and the area of each of the precipitates having a major axis a of 5 nm or more were measured using an image analyzer (manufactured by Nireco Corporation, trade name Luzex). Select 100 randomly from these deposits, with the average of the aspect ratio a _ta / b _ta the major axis determined from the mean a _ta and and average b _ta of minor all these precipitates, respectively major axis a, the minor axis b and aspect ratio a / b. The total area of all precipitates having a major axis a of 5 μm or more was taken as the total area of all precipitates. The ratio of the total area of the precipitates having a major axis a of 10 nm to 50 nm and an aspect ratio a / b of 1 to 5 was defined as an area ratio C (%) with respect to the total area of all the precipitates.
In addition, by the final cold rolling (usually processing strain η = 2 or more), Ni—P-based precipitates having a major axis of 20 nm or less or precipitates having a major axis exceeding 20 nm but having an aspect ratio exceeding 3 are dissolved. However, it was confirmed that a precipitate having an aspect ratio of 1 to 3 at 20 nm or more maintained its major axis, minor axis and aspect ratio even after the final cold rolling. Also, the area ratio C of the precipitates hardly changed even after the final cold rolling because the precipitates exceeding 200 nm were not dissolved.

Examples of the high-strength, high-conductivity copper alloy excellent in hot workability according to the present invention will be described with respect to the copper alloys having the composition shown in Table 1 together with comparative examples.
Alloy Examples 1 to 6 of the present invention had excellent strength and conductivity without cracking during hot rolling.
On the other hand, Comparative Examples 7 to 18 are alloys with components out of the alloy composition range or Ni / P ratio of the present invention. In Comparative Examples 7 to 10, there was no addition of B or less than the specified amount, and therefore cracking occurred during hot rolling. Since Comparative Example 11 has an addition amount of Ni exceeding 2.0%, Comparative Example 12 has an addition amount of P exceeding 0.50%, and Comparative Example 13 has a total addition amount of Sn and In. Since it exceeds 1.0%, in Comparative Example 14, the total amount of Sn exceeds 1.0%, and thus cracks occurred during hot rolling. In Comparative Example 15, since the Ni / P ratio deviated from an appropriate composition ratio, the amount of dissolved P increased and the conductivity decreased. In Comparative Example 16, since the Ni / P ratio deviates from an appropriate composition ratio, the amount of Ni dissolved increases and the conductivity decreases, and the amount of precipitation is small, so the strength is low. In Comparative Example 17, since the B addition amount exceeds 0.070%, Ni—P-based precipitates are reduced due to crystallization or precipitation of compounds such as Ni—P—B and BP during solidification. In addition, strength and conductivity are low, and bending workability is inferior. Comparative Example 18 has low strength because the amounts of Ni and P added deviate from the range defined by the present invention.
Appearance photograph after hot rolling test Shown in FIGS. 1 is a sample of the present invention example 3, FIG. 2 is a sample of comparative example 8, FIG. 3 is a sample of comparative example 9, and FIG.

Invention Examples and Comparative Examples 19-39
Sample preparation (b):
Electrical copper or oxygen-free copper as the main raw material, nickel (Ni), 15% P-Cu master alloy (P), 2% B-Cu master alloy (B), tin (Sn), indium (In) as auxiliary raw materials And melted in a high-frequency melting furnace in a vacuum or argon atmosphere, and cast into an ingot of 45 × 45 × 90 mm or φ50 × 90 mm. In order to change the cooling rate during casting and solidification, the mold material was made of cast iron, alumina, or silica. As a result of measuring the cooling rate from 1100 to 950 ° C. during casting and solidification by inserting a thermocouple into the center of the mold, the cast iron mold was 340 ° C./min, the alumina mold was 85 ° C./min, and the silica mold was 33 ° C./min. Minutes. In order to produce ingots with a cooling rate of 20 ° C./min or less, ingots with cooling rates of 20 ° C./min, 15 and 10 ° C./min were obtained with a unidirectional solidification apparatus. Ingots were subjected to a hot rolling test, and ingots that were not cracked by hot rolling were subjected to hot rolling and solution treatment, aging treatment, intermediate cold rolling, aging treatment, final cold rolling, and strain relief annealing. It implemented in order and was set as the flat plate of thickness 0.10mm. Various test pieces of the obtained plate material were collected and tested, and “strength”, “conductivity” and “bending workability” were evaluated.

Ingot hot workability evaluation (b):
The ingot was evaluated for hot workability A, except that the ingot was cut to 45 × 45 × 45 mm or φ50 × 45 mm, heated to 850 ° C. for 1 hour, and then subjected to a hot rolling test in 4 passes from a thickness of 45 mm to 12 mm. As well as.

Inclusion evaluation of test piece (b):
The inclusions in the sample were evaluated in the order of hot rolling and solution treatment, aging treatment, intermediate cold rolling, aging treatment, final cold rolling, and strain relief annealing, and a flat plate sample having a thickness of 0.10 mm. The rolled parallel section was mirror-polished, and 5 views (about 0.35 mm ² ) of inclusions having a size of 5 μm or more at 500 times the electron microscope SEM image were observed, and the number of inclusions per 1 mm ² was calculated. On the other hand, with respect to those in which cracking occurred in the hot workability evaluation of the ingot, the inclusion was evaluated using a water-cooled sample after heating the ingot to 850 ° C. for 1 hour. The sample was mirror-polished, and the inclusions were observed with an electron microscope in the same manner as the flat plate sample described above, and the number of inclusions per 1 mm ² was calculated. When the number of inclusions was compared between the flat sample and the ingot heated at 850 ° C. for 1 hour and the water-cooled sample for the alloy having good hot workability, almost the same results were obtained.

Physical property evaluation of test piece (b):
About "strength", it carried out using the No. 13 B test piece by the tension test prescribed | regulated to JISZ2241, and measured the tensile strength. “Conductivity” was measured in% IACS by measuring the electrical resistance of the test piece using the double bridge method. “Bending workability” was evaluated by a 90 ° W bending test. The test was performed in accordance with CES-M0002-6, and bending was performed 90 degrees with a load of 50 kN using an R-0.1 mm jig. In the evaluation of the bent portion, the state of the surface of the central mountain was observed with an optical microscope. The bending axis was set at a right angle to the rolling direction (Good way).

Examples of the high-strength, high-conductivity copper alloy excellent in hot workability according to the present invention will be described with respect to the copper alloys having the composition shown in Table 1 together with comparative examples.
Alloy Examples 19 to 26 of the present invention had excellent strength and conductivity without cracking during hot rolling. Inventive Example 22 has a slow cooling rate of 20 ° C./min during casting, and therefore has a larger number of inclusions and is slightly inferior in bending workability as compared with other inventive examples.
On the other hand, when the results of Comparative Examples 9 to 21 are examined, Comparative Examples 27 to 39 are alloys with components out of the alloy composition range or Ni / P ratio of the present invention. In Comparative Examples 27 to 29, there was no addition of B or less than the specified amount, and therefore cracking occurred during hot rolling. Since Comparative Example 30 has an addition amount of Ni exceeding 2.0%, Comparative Example 31 has an addition amount of P exceeding 0.50%, and Comparative Example 32 has a total addition amount of Sn and In. Since it exceeds 1.0%, since the total amount of Sn added exceeds 1.0% in Comparative Example 33, cracks occurred during hot rolling. In Comparative Example 34, since the Ni / P ratio deviated from an appropriate composition ratio, the amount of dissolved P increased and the conductivity decreased. In Comparative Example 35, since the Ni / P ratio deviates from an appropriate composition ratio, the amount of Ni dissolved increases and the conductivity decreases, and the amount of precipitation is small, so the strength is low. In Comparative Example 36, the addition amount of B exceeds 0.070%, and thus the amount of Ni-P-based precipitates decreased due to crystallization or precipitation of compounds such as Ni-P-B and BP during solidification. , Strength and conductivity are low and bending workability is inferior. In Comparative Examples 37 to 39, the cooling rate during casting was less than the specified value, which was less than 20 ° C./min, and therefore cracking occurred during hot rolling.

It is an external appearance photograph of the sample edge part after the hot rolling test in Example 3 of this invention. 14 is an appearance photograph of a sample edge portion after a hot rolling test in Comparative Example 8. 14 is an appearance photograph of a sample edge portion after a hot rolling test in Comparative Example 9. It is an external appearance photograph of the sample edge part after the hot rolling test in Comparative Example 10.

Claims (7)

  Ni: 1.0% to 2.0%, P: 0.1% to 0.5% in terms of mass ratio, Ni / P content ratio Ni / P: 4.0 to 6.5 And B: 0.005% to 0.070%, the balance being made of Cu and inevitable impurities, a copper alloy having excellent hot workability.   Ni: 1.0% to 2.0%, P: 0.1% to 0.5% in terms of mass ratio, Ni / P content ratio Ni / P: 4.0 to 6.5 And B: 0.005% to 0.070%, and further contains one or more of Sn and In in a total of 0.01% to 1.0%, with the balance being Cu and inevitable impurities. A copper alloy with excellent hot workability. The number of inclusions having a major axis of 5 to 50 µm is 100 or less per 1 mm ² , and the number of inclusions having a major axis exceeding 50 µm is 0 per 1 mm ^2. Copper alloy.   The copper with excellent hot workability according to any one of claims 1 to 3, wherein the major axis a of the Ni-P-based precipitate before final cold rolling is 20 nm to 50 nm and the aspect ratio a / b is 1 to 5. alloy.   The copper alloy excellent in hot workability according to any one of claims 1 to 4, wherein the tensile strength is 700 MPa or more and the conductivity is 40% IACS or more.   The method for producing a copper alloy having excellent hot workability according to any one of claims 1 to 5, wherein an average cooling rate from 1100 ° C to 950 ° C during casting is 20 ° C / min or more.   The manufacturing method according to claim 6, wherein an average cooling rate from 1100 ° C to 950 ° C during casting is 30 ° C / min or more.

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