JP4937628B2 - Copper alloy with excellent hot workability - Google Patents

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 removed by a mold, and the inside solidifies over some time except for several 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 prevent a Cu-Ni-P-Mg alloy having excellent hot workability by preventing cracks occurring during casting, cooling, hot working heating or hot working. It is something to be offered.

The present inventors have conducted research to achieve the above object, and as a result, the following structure is specified, whereby a Cu-Ni-P-Mg system having excellent hot workability, excellent strength and conductivity is provided. It has been found that an alloy can be obtained.
In the copper alloy according to the present invention, Ni: 1.0% to 2.0% (in the present specification,% representing the component ratio is mass%), P: 0.10% to 0.50%, Mg: 0 0.01% to 0.20%, Ni / P content ratio Ni / P: 4.0 to 6.5, and B: 0.005% to 0.070% with the balance being Cu and Ri inevitable impurities, about the size and shape of the final cold rolling before the Ni-P-Mg-based precipitates, major axis: a, minor: when is b, at least an aspect ratio a / b is from 2 to 50 In addition, the total of the areas of the precipitates with the minor axis b of 10 to 25 nm, the deposits with the aspect ratio a / b of less than 2, and the major axis a of 20 to 50 nm is the total in the copper alloy. to 80% or more with respect to the total sum of the areas of the precipitates are excellent copper alloy in hot workability characterized by, preferred Ku is the number of major axis 5~50μm of inclusions is not more than 100 per 1 mm ^2, and the number of inclusions exceeding diameter 50μm is directed to copper alloys is 0 per 1 mm ^2.

In the present invention, by adding a specific amount of B to a Cu—Ni—P—Mg alloy, crystallization or precipitation of the Ni—P—Mg compound at the crystal grain boundary is suppressed, preferably cooling during casting. By controlling the speed, the formation of coarse Ni—P—Mg—B and PB compounds is suppressed. 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—Mg 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 precipitation by aging treatment becomes more prominent and fine Ni-P-Mg having a size of 50 nm or less. It becomes difficult to control the precipitation. 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 0.10%, precipitation of the compound is insufficient, so that the desired strength cannot be obtained. On the other hand, when the P content exceeds 0.50%, 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 0.10% to 0.50%, preferably 0.20 to 0.40%.
[Mg amount]
Mg precipitates a compound with Ni and P to improve the strength and heat resistance of the alloy. Further, when Mg is added, a Ni-P-Mg-based fibrous precipitate is generated, and higher strength can be obtained as compared with a Cu-Ni-P-based alloy not added with Mg. Furthermore, the effect is greater than the increase in strength obtained when Mg is dissolved in the matrix. However, when the Mg content is less than 0.01%, desired strength and heat resistance cannot be obtained. On the other hand, when the Mg content exceeds 0.20%, hot workability is remarkably lowered and the conductivity is remarkably lowered. In addition, coarse precipitates are generated, and improvement in strength is hindered.
Therefore, the Mg content of the alloy of the present invention is 0.01% to 0.20%, preferably 0.02% to 0.15%.

[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 to 6.5, preferably 4.5 to 6.0.

[Size and area ratio of Ni-P-Mg-based precipitates]
When the major axis of the Ni—P—Mg based precipitate is classified as a (nm) and the minor axis is b (nm) according to the aspect ratio a / b, the copper alloy has a large aspect ratio of about a / b = 2-50. It is possible to produce acicular and fibrous precipitates having a / b of less than 2. By making the processing strain η before aging treatment less than 0.4, preferably less than 0.1, acicular and fibrous precipitates, and by making the processing strain η before aging treatment 0.4 or more A precipitate is formed.
The reason for defining the size of the precipitate is as follows. Precipitates whose minor axis b before final cold rolling is less than 10 nm are subjected to a rolling process with a work strain η = 2 or more, and the precipitates are broken and decomposed and re-dissolved in copper. Lowering is not preferable. On the other hand, a precipitate having a minor axis b of 10 nm or more before the final cold rolling is not easily re-dissolved even in a rolling process with a work strain η = 2 or more, and exists as a precipitate of 10 nm or more. In particular, precipitates having a minor axis b of 20 nm or more have little change in size before and after rolling, and the precipitates are not easily broken or dissolved by cold working. On the other hand, the precipitate with the major axis a before rolling exceeding 50 nm and the minor axis b exceeding 25 nm maintains its size after rolling, but the volume of the individual precipitates is large, so the precipitates in the copper alloy Since the dispersion interval becomes too large, precipitation strengthening and work strengthening cannot be obtained.
The major axis a and the minor axis b are total precipitates obtained by cutting the alloy strips before the final cold rolling in a direction perpendicular to the thickness parallel to the rolling direction, and measuring all of the precipitates of 5 nm or more using an image analyzer. It is the average value of the major axis and minor axis of the product. 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 size of the Ni—P—Mg-based precipitate before the final cold rolling of the alloy of the present invention is such that the aspect ratio a / b is 2 to 50 and the minor axis b is 10 to 25 nm. In addition, the aspect ratio a / b is less than 2 and the major axis a is 20 to 50 nm.

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.
When the area ratio C is less than 80%, there are many precipitates having a major axis a exceeding 50 nm and a minor axis b exceeding 25 nm, or a major axis a being less than 20 nm, or a minor axis b being less than 10 nm. Is the case. For example, a Ni-P of 1000 nm or more in which precipitates having a major axis a exceeding 50 nm and a minor axis b exceeding 25 nm or crystallized substances generated during melt casting remained without being dissolved by hot rolling or solution treatment. When there are a lot of system particles (crystallized products), the number of fine precipitates in the range defined in the present invention that contributes to strength improvement is small, and the dispersion interval between the precipitates is large. The desired strength is not obtained. On the other hand, a precipitate having a major axis “a” of less than 20 nm or a minor axis “b” of less than 10 nm is re-dissolved by the rolling process, and thus the desired conductivity cannot be obtained.

[B amount]
B suppresses crystallization or precipitation of the Ni-P-Mg-based compound at the grain boundary during the solidification of the Cu-Ni-P-Mg-based alloy, during the cooling process after the solidification, and during heating during hot working. Improves hot workability. However, if the content is less than 0.005%, the effect of improving the hot workability cannot be obtained. On the other hand, if B is contained in excess of 0.070%, the Ni-P-Mg-B system, B A compound such as a -P compound is generated as an inclusion during dissolution or coagulation. Since these B-containing compounds usually crystallize or precipitate with agglomeration and coarsening at the grain boundaries and do not form a solid solution in the Cu matrix by solution treatment, Ni-P- precipitated by aging treatment. Mg-based compounds are reduced, and the strength of the alloy is reduced. Furthermore, Ni-P-Mg-B, BP, and other compounds remain in the product as inclusions having a major axis of 5 μm or more, surface defects of the product, starting points of cracks during bending, plating treatment This is not preferable because it becomes a starting point of defects at the time. 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 refers to a Ni—P—Mg—B compound, BP crystallized or precipitated in a grain boundary and / or crystal grain in a Cu—Ni—P—Mg alloy. It means a crystallized product mainly composed of a system compound or the like, and does not include a fine Ni—P—Mg compound that crystallizes or precipitates in 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 of more than 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 1 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—Mg based alloy that satisfies 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, and final cold rolling. In the strain relief annealing and the like, it can be produced 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 of 1100 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—P—Mg—B system and / or the PB system compound Is likely to be coarsely formed in the solidification stage, and there is a possibility that the improvement of hot ductility due to the addition of B is not recognized.

The following correlation was recognized between the number of inclusions mainly composed of the Ni-P-Mg-B and / or PB 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 30 ° C./min in the casting and solidification stage to 850 ° C. for 1 hour and then cooling with water, 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 added with a predetermined amount of B Cracking occurred. Accordingly, the cooling rate from 1100 ° C. to 950 ° C. in the casting and solidification stage is preferably 30 ° 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. 85 ° 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 Examples 1-6 and Comparative Examples 7-20
Sample preparation (a):
Mainly made of electrolytic copper or oxygen-free copper, nickel (Ni), 15% P—Cu master alloy (P), 10% Mg—Cu master alloy (Mg), 2% B—Cu master alloy (B), tin (Sn) and indium (In) were used as auxiliary materials, 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 mold. 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—Mg 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 it is 100 to 2000 nm, the field is 50,000 times to Images were taken with a field of view of 100,000 times (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 were individually measured for all the precipitates having a major axis a of 5 nm or more using an image analyzer (trade name Luzex, manufactured by Nireco Corporation). 100 of these precipitates are taken out at random, and the area of the precipitates having an aspect ratio a / b of 2 to 50 and a minor axis b of 10 to 30 nm with respect to the total area of all precipitates having a major axis a of 5 nm or more. The ratio of the total area of the precipitates having an aspect ratio of less than 2 and a major axis a of 20 to 50 nm was calculated as an area ratio C (%).
In addition, by the final cold rolling (usually processing strain η = 2 or more), Ni—P—Mg-based precipitates having a minor axis b of less than 10 nm in solid precipitates before cold rolling are not observed as solid solutions, It was confirmed that the precipitate having a minor axis b of 10 nm or more maintains its major axis, minor axis and aspect ratio even after the final cold rolling. Similarly, the area ratio C of the precipitate hardly changes after the final cold rolling.

Examples of the high-strength, high-conductivity copper alloy excellent in hot workability according to the present invention will be described with reference to the copper alloys having the component compositions 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 20 are alloys in which the range of the alloy composition of the present invention or the Ni / P ratio and the size of precipitates are out of the range. Since Comparative Examples 7 to 8 and B were not added or were less than the specified amount, cracking occurred during hot rolling. In Comparative Example 9, the amount of Ni added exceeds 2.0%, and in Comparative Example 10, the amount of P added exceeds 0.50%, and the Ni / P ratio deviates. Since the amount exceeds 1.0%, in Comparative Example 12, the total amount of Sn and In added exceeds 1.0%, and thus cracks occurred during hot rolling. In Comparative Example 13, since the added amount of Mg exceeded 0.20%, cracks occurred during hot rolling. In Comparative Example 14, since the major axis of the precipitate is as small as 12 nm and the area ratio C is zero, the precipitate is dissolved in cold rolling, the conductivity is low, and the bending workability is also poor. In Comparative Example 15, since the precipitate is too large and the area ratio C is zero, the tensile strength is low. In Comparative Example 16, since no Mg was added, the tensile strength was low. In Comparative Example 17, since the amount of B added exceeds 0.070%, a compound such as Ni—P—Mg—B or BP crystallizes or precipitates during solidification, so that precipitation of Ni—P—Mg system occurs. The amount is reduced, the strength and conductivity are low, and the bending workability is poor. In Comparative Example 18, since the Ni / P ratio deviated from an appropriate composition ratio, the amount of dissolved P increased and the conductivity decreased. In Comparative Example 19, since the Ni / P ratio deviated from an appropriate composition ratio, the amount of Ni dissolved increased and the conductivity decreased. Comparative Example 20 has low strength because the addition amounts of Ni and P deviate from the range defined by the present invention.

Invention Examples 21 to 26 and Comparative Examples 27 to 38
Sample preparation (b):
Mainly made of electrolytic copper or oxygen-free copper, nickel (Ni), 15% P—Cu master alloy (P), 10% Mg—Cu master alloy (Mg), 2% B—Cu master alloy (B), tin (Sn) and indium (In) were used as auxiliary materials, melted in a high-frequency melting furnace in a vacuum or in an 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 cross 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 and high-conductivity copper alloy excellent in hot workability according to the present invention will be described with respect to the copper alloys having the component compositions shown in Table 2 together with comparative examples.
Invention Examples 21 to 26 had excellent strength and electrical conductivity without cracking during hot rolling. Inventive Examples 23 and 26 have a cooling rate as low as 33 ° C./min during casting, so that the number of inclusions is large and bending workability is slightly inferior as compared with other inventive examples.

  On the other hand, when the results of Comparative Examples 27 to 38 were examined, Comparative Examples 27 to 29 had a slow cooling rate of 1100 to 950 ° C., so the number of inclusions was large, and cracks occurred during hot rolling. About Comparative Examples 31-38, it is an alloy with the component remove | deviated from the range of the alloy composition of this invention, or Ni / P ratio. In Comparative Examples 31 to 32, since B was not added or was less than the specified amount, cracking occurred during hot rolling. In Comparative Example 33, the addition amount of Ni exceeds 2.0%, and in Comparative Example 34, the addition amount of P exceeds 0.50%. Therefore, in Comparative Example 35, the addition amount of Mg is 0.20%. In Comparative Examples 36 to 37, since the total amount of Sn and In exceeds 1.0%, cracks occurred during hot rolling.

In Comparative Example 38, since the Ni / P ratio deviated from an appropriate composition ratio, the amount of dissolved P increased and the conductivity decreased. In Comparative Example 39, since the amount of addition of B exceeds 0.070%, Ni-P-Mg-based compounds such as Ni-P-Mg-B-based and BP-based crystals crystallize or precipitate during solidification. The amount of precipitates is reduced, the tensile strength and conductivity are low, and the bending workability is poor. Since the comparative example 40 has low Ni addition amount, its tensile strength is low.

Claims (4)

Ni: 1.0% to 2.0%, P: 0.10% to 0.50%, Mg: 0.01% to 0.20% in terms of mass ratio, content of Ni and P the ratio Ni / P: 4.0 to 6.5 and at, B: 0.010% to 0.070%, the balance Ri consists Cu and unavoidable impurities,
About the magnitude | size and shape of the Ni-P-Mg type | system | group precipitate before final cold rolling, when a major axis: a and a minor axis: b, at least the aspect ratio a / b is 2-50 and the minor axis b is 10-10. The sum of the areas of the precipitates having a precipitate of 25 nm, the left deposit and the aspect ratio a / b of less than 2 and the major axis a of 20 to 50 nm is the sum of the areas of all the precipitates in the copper alloy. Copper alloy excellent in hot workability characterized by occupying 80% or more . Ni: 1.0% to 2.0%, P: 0.10% to 0.50%, Mg: 0.01% to 0.20% in terms of mass ratio, content of Ni and P The ratio Ni / P is 4.0 to 6.5 and B is 0.005% to 0.070%, and at least one of Sn and In is 0.01% to 1.0% in total. hereinafter wherein the balance Ri consists Cu and unavoidable impurities,
About the magnitude | size and shape of the Ni-P-Mg type | system | group precipitate before final cold rolling, when a major axis: a and a minor axis: b, at least the aspect ratio a / b is 2-50 and the minor axis b is 10-10. The sum of the areas of the precipitates having a precipitate of 25 nm, the left deposit and the aspect ratio a / b of less than 2 and the major axis a of 20 to 50 nm is the sum of the areas of all the precipitates in the copper alloy. Copper alloy excellent in hot workability characterized by occupying 80% or more . 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 alloy excellent in hot workability according to any one of claims 1 to 3, wherein the tensile strength is 700 MPa or more and the electrical conductivity is 40% IACS or more.