JP2002003965A - Copper alloy for electronic and electric apparatus excellent in bending workability and stress relaxation property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy for electronic and electric apparatus excellent in bending workability and a stress relaxation property, and suitable for connectors or terminals used for electronic and electric apparatus and automobiles. SOLUTION: This copper alloy for electronic and electric apparatus has a composition containing, by weight, 3.0 to 9.0% Sn and Fe and P by 0.05 to 1.0% in total, in which the atomic weight ratio of Fe to P shown by the formula of [Fe/P] is 0.2 to 3.0, and the balance Cu with ineivtalbe impurities and is obtained by carrying out heat treatment of performing heating at 500 to 900 deg.C for 10 to 100 sec to form a recrystallied structure having a crystal grain size of <=5 μm and thereafter performing final cold working. Sn contributes to the improvement of its mechanical properties, Fe and P are dispersed into the Cu base phase as an Fe-P compound and are made into recrystallized nuclei at the time of the above heat treatment to refine the crystal grains and to improve its bending workability. Further, a part of the above Fe-P compound reenters into solid solution at the time of the above heat treatment to improve its stress relaxation properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy for electronic and electrical equipment having excellent bending workability and stress relaxation resistance suitable for connectors and terminals used for electronic and electrical equipment and wiring in automobiles.

[0002]

2. Description of the Related Art Iron-based materials or copper-based materials such as phosphor bronze, copper bronze, and brass, which have excellent thermal and electrical conductivity, are used for electronic components such as connectors and terminals used in electronic and electrical equipment and wiring in automobiles. It is used. In recent years, as electronic equipment has become smaller, lighter and more densely packed,
There is a strong demand for materials for electronic components such as connectors to have high strength and excellent stress relaxation resistance, which is important for electrical connectivity.

[0003]

The strength is easily increased by work hardening. However, the work hardened material is inferior in toughness, so that bending cracks occur when it is processed into a terminal or the like. There is a problem that good electrical connectivity cannot be obtained due to poor characteristics. For these reasons, the present inventors have made various studies on the improvement in bending workability and stress relaxation characteristics of a phosphor bronze alloy that is frequently used, and have specified the alloy composition and heat treatment conditions before final cold working. As a result, it was found that the bending workability and the stress relaxation property could be improved, and further research was carried out to complete the present invention. An object of the present invention is to provide a copper alloy for electronic and electrical equipment having excellent bending workability and stress relaxation resistance.

[0004]

According to the first aspect of the present invention,
It contains 3.0 to 9.0 wt% of Sn and 0.05 to 1.0 wt% of Fe and P in total, and the atomic weight ratio of Fe and P represented by the formula of [Fe / P] is 0.2 to 2.0 wt%. 3.0
The remainder is a copper alloy consisting of Cu and unavoidable impurities, and is subjected to a heat treatment of heating at a temperature of 500 to 900 ° C. for 10 to 100 seconds to form a recrystallized structure having a crystal grain size of 5 μm or less. It is a copper alloy for electronic and electrical equipment which is excellent in bending workability and stress relaxation resistance characterized by being processed.

According to a second aspect of the present invention, Sn is adjusted to 3.0 to 3.0.
9.0 wt%, Fe, Ni and P in total of 0.05 to
1.0 wt%, and the Fe, Ni and P [(F
e + Ni) / P] is 0.2 to 0.2.
3.0, the balance being a copper alloy consisting of Cu and unavoidable impurities, at a temperature of 500 to 900 ° C. and 10 to 10
Heat treatment for 0 seconds to obtain a recrystallized structure with a crystal grain size of 5 μm or less, and then subjected to final cold working. It is a copper alloy.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The copper alloy according to the first aspect of the present invention is
A copper alloy containing appropriate amounts of n, Fe, and P is subjected to a predetermined heat treatment, and then subjected to final cold working. The copper alloy is manufactured by dispersing in the copper alloy by defining the heat treatment conditions. The Fe-P compound becomes a recrystallization nucleus to reduce the crystal grain size after the heat treatment to 5 μm or less, thereby improving bending workability. This copper alloy is also excellent in stress relaxation resistance.
This is because a part of the e-P compound is dissolved again. The grain size is such that the Fe-P compound is 0.01 to 1 after the heat treatment.
In the case where the particles are uniformly dispersed in a size of μm, the particles are particularly uniformly finely formed, and the bending workability is further improved.

[0007] In the copper alloy according to the first aspect of the present invention, Sn
Contributes to the improvement of mechanical properties. Sn content of 3.0
The reason for defining the content to be 9.0 wt% is that if the content is less than 3.0 wt%, the effect cannot be sufficiently obtained, and if the content is more than 9.0 wt%, the manufacturing processability decreases. As described above, Fe and P are dispersed as a Fe-P compound in the copper alloy, and serve as recrystallization nuclei during the heat treatment to refine crystal grains and improve bending workability. Re-dissolve to improve stress relaxation resistance.

In the present invention, the reason why the total content of Fe and P is defined as 0.05 to 1.0 wt% is as follows.
If the content is less than 0.05 wt%, the effect cannot be sufficiently obtained.
If the content exceeds 1.0% by weight, the workability of the production is reduced. In the present invention, the reason why the atomic weight ratio represented by the formula of [Fe / P] is defined to be 0.2 to 3.0 is that when the atomic weight ratio is less than 0.2, the amount of the P compound is small, and If the atomic weight ratio exceeds 3.0, Fe that does not become an Fe-P compound forms a solid solution in the copper alloy and the electrical conductivity of the copper alloy decreases.

A second aspect of the present invention is a copper alloy obtained by adding Ni to the copper alloy according to the first aspect of the present invention.
Is dispersed in a copper alloy together with the Fe-P compound as a Ni-P compound, an Fe-Ni-P compound,
It becomes a recrystallization nucleus during heat treatment before the final cold rolling, refines crystal grains and improves bending workability, and at the same time, a part of the above compounds re-dissolves to improve stress relaxation resistance. Others are the same as those of the first aspect of the invention.

In the present invention, the reason why the heat treatment condition before the final cold working is defined as a condition of heating at a temperature of 500 to 900 ° C. for 10 to 100 seconds is that even if the temperature is lower than 500 ° C.
In less than a second, recrystallization does not proceed sufficiently, resulting in poor bending workability. In addition, P compounds (Ni-P, Fe-Ni-P, Fe
-P compound etc.) do not sufficiently re-dissolve in solid solution and have poor stress relaxation resistance. On the other hand, when the temperature exceeds 900 ° C. or exceeds 100 seconds, the elements constituting the P compound are re-dissolved to reduce the number of crystal nuclei. As a result, the crystal grains are not sufficiently refined, and the conductivity also decreases. To do that. The heat treatment is preferably performed using a continuous annealing furnace because of its high productivity. The copper alloy of the present invention is adjusted to an appropriate strength by final cold working after the heat treatment. It is desirable to perform a heat treatment after the final cold working to remove internal stress.

[0011]

The present invention will be described below in detail with reference to examples. (Example 1) A Cu-Sn-Fe-P alloy having an alloy composition specified in the invention described in claim 1 shown in Table 1 was melted in a high-frequency melting furnace and DC-cast at a cooling rate of 10 to 30 ° C / sec. Thus, an ingot having a thickness of 30 mm, a width of 100 mm, and a length of 150 mm was obtained. Next, the ingot was subjected to a homogenization treatment of heating at 800 ° C. for 1 hour and gradually cooled. Next, both surfaces were chamfered to remove the oxide film, and then cold-rolled to a thickness of 1.2 m.
m plate material, and then heat-treated at 700 ° C. for 1 hour in an inert gas atmosphere and gradually cooled. The heat-treated material having a thickness of 1.2 mm was subjected to cold rolling, heat treatment (400 to 600 ° C. × 1 hour), and cold rolling in this order to obtain a sheet material having a thickness of 0.35 mm. Next, this plate is heated at 500-900 ° C for 10-1.
A heat treatment a was performed for 00 seconds, followed by final cold rolling to a thickness of 0.25 mm, and then a heat treatment at 250 ° C. for 0.5 hour to remove internal stress.

(Comparative Example 1) Except for using a Cu-Sn-Fe-P alloy having a composition outside the range specified in claim 1 shown in Table 1,
A copper alloy plate was manufactured in the same manner as in Example 1.

(Comparative Example 2) A copper alloy plate was manufactured in the same manner as in Example 1 except that the heat treatment b was performed under conditions other than those specified in the present invention.

For each of the copper alloy sheets produced in Example 1 and Comparative Examples 1 and 2, (1) mechanical properties (tensile strength: T
S, 0.2% yield strength: YS) (2) bending workability, (3) stress relaxation resistance, and (4) manufacturing workability were investigated. Further, (5) the crystal grain size after the heat treatment b and (6) the dispersion state of the Fe-P compound were investigated. The results are shown in Table 1. The survey method is described below. (1) Mechanical properties were determined by JI cut out parallel to the rolling direction.
Three S-13B test pieces were measured according to JIS-Z2241, and the average value was shown. (2) The bending workability was determined by cutting out a test piece having a length of 25 mm and a width of 10 mm, bending the test piece in the length direction with a bending radius R = 0, and observing the bent portion with an optical microscope at a magnification of 50 times. A, no cracks and rough skin occurred A, slightly roughened skin B, roughened skin C, cracked slightly cracked other than rough skin D, cracked whole Rank E and A to C are good (○ practical)
D and E were determined to be defective (x not practical). A test piece whose length direction and rolling direction are parallel (Good Way: G
W) and the one whose length direction and rolling direction are perpendicular (Bad Way: B
W) were prepared. (3) The stress relaxation resistance was determined by obtaining the stress relaxation rate according to the standard plan of the Electronic Materials Industries Association of Japan, EMAS-3003. As shown in FIG. 1 (a), the stress relaxation rate is determined by applying a support base 2 to the other end of a test piece 1 having one end fixed thereto.
(Bending amount corresponding to 0.2% proof stress × 0.8), and after heating at 150 ° C. for 1000 hours in this state, the support table 2 was removed as shown in FIG. The permanent deflection δt = Ht−H1 remaining in the test piece 1 was measured, and the values were determined by substituting δ0 and δt into the equation of (δt / δ0) × 100%. A stress relaxation rate of 38% or less was determined to be good. (4) Manufacturability was evaluated based on the occurrence of cracks during hot rolling and cold rolling. (5) The grain size was measured by observing the recrystallized structure after the heat treatment b with a scanning electron microscope and according to the cutting method of JIS-H0501. (6) The dispersion state of the Fe—P compound is good when the number of P compounds having a diameter of 0.01 to 1 μm is 80% or more of the total number by taking a photograph of 5,000 to 100,000 times with a transmission electron microscope (O). , Quasi-good when less than 80% and 50% or more (△), 5
When it was less than 0%, it was determined to be defective (x).

[0015]

[Table 1]

As is apparent from Table 1, N of the present invention example
o. In all of Nos. 1 to 14, the crystal grains after the heat treatment b were 5 μm.
m or less, and the number of P compounds (here, Fe-P compounds) having a diameter of 0.01 to 1 μm occupies 80% or more of all the compounds, and has mechanical properties, bending workability, stress relaxation properties, and manufacturing workability. Excellent. On the other hand, in Comparative Example No. 15 is S
Since the content of n was small, the mechanical properties were poor. No. 1
No. 6 has a large Sn content, and Sample No. 18 was inferior in manufacturing workability because of a large total content of Fe and P.
No. No. 17 has a small total content of Fe and P,
o. No. 19 has a small Fe / P ratio, and Sample No. 20 was inferior in bending workability and stress relaxation characteristics because of a large Fe / P ratio. In addition, No. No. 21 has a short heat treatment time. In No. 22, since the heat treatment temperature was low, the crystal grains were not sufficiently refined and the P compound was not sufficiently re-dissolved in any of them, so that the bending workability and the stress relaxation property were inferior. No. No. 23 has a long heat treatment time. In No. 24, since the heat treatment temperature was high, the P compound re-dissolved in the solid solution, the crystal grains became coarse, and the bending workability was poor.

(Example 2) A copper alloy plate was produced in the same manner as in Example 1 except that a Cu-Sn-Fe-Ni-P alloy having a composition defined in claim 2 shown in Table 2 was used. .

Comparative Example 3 A copper alloy plate was manufactured in the same manner as in Example 2 except that the heat treatment a was performed under conditions outside the range specified in the present invention.

For each of the copper alloy sheets produced in Example 2 and Comparative Example 3, (1) grain size, (2) tensile strength,
(3) The bending workability and (4) the stress relaxation property were measured in the above paragraph 0.
The test was performed by the method described in No. 013. The results are shown in Table 2.

[0020]

[Table 2]

As is clear from Table 2, N of the present invention example
o. All of Nos. 31 to 36 were excellent in mechanical properties, bending workability, and stress relaxation properties. On the other hand, N
o. In Nos. 37 and 38, since the heat treatment time was long, the P compound was re-dissolved and the crystal grains became coarse and the bending workability was poor. No. In Examples 39 and 40, since the heat treatment temperature was low, the crystal grains were not sufficiently refined, the P compound was not sufficiently re-dissolved, and the bending workability and stress relaxation characteristics were inferior.

[0022]

As described above, in the copper alloy according to the first aspect of the present invention, a predetermined heat treatment is applied to a copper alloy containing Sn, Fe, and P in appropriate amounts, and then a final cold working is performed. It is a copper alloy, and the Sn contributes to improvement of mechanical properties, and F
e and P are dispersed in the Cu matrix as Fe-P compounds, and serve as recrystallization nuclei during the heat treatment to refine crystal grains and improve bending workability. Further, a part of the Fe-P compound re-dissolves during the heat treatment to improve stress relaxation characteristics.
A copper alloy according to a second aspect of the present invention is a copper alloy according to the first aspect of the present invention, further containing an appropriate amount of Ni, wherein Ni is Ni-
Forming a P compound or an Fe-Ni-P compound,
Since the same action as the e-P compound is achieved, the same effect as the first aspect of the present invention can be obtained. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams of a test method of stress relaxation resistance.

[Explanation of symbols]

 1 test piece 2 support

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 661 C22F 1/00 661A 682 682 685 685Z 691 691B 691C

Claims (2)

[Claims] 1. An alloy containing 3.0 to 9.0 wt% of Sn and 0.05 to 1.0 wt% of Fe and P in total.
And the atomic weight ratio of P expressed by the formula [Fe / P] is 0.
2 to 3.0, the balance being a copper alloy consisting of Cu and unavoidable impurities.
A heat treatment of heating for 100 seconds to obtain a recrystallized structure having a crystal grain size of 5 μm or less, and then a final cold working is performed, which is excellent in bending workability and stress relaxation resistance. Copper alloy. 2. Sn of 3.0 to 9.0 wt%, Fe, N
i and P are contained in a total amount of 0.05 to 1.0 wt%, and the atomic weight ratio of Fe, Ni and P represented by the formula [(Fe + Ni) / P] is 0.2 to 3.0, and the balance is Is Cu
And a copper alloy comprising unavoidable impurities,
Bending workability and stress relaxation resistance characterized by being subjected to a heat treatment of heating at 900 ° C. for 10 to 100 seconds to form a recrystallized structure having a crystal grain size of 5 μm or less, and then subjected to final cold working. Excellent copper alloy for electronic and electrical equipment.