JPH11335800A - Production of copper base alloy with excellent stress relaxation resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a copper base alloy having an excellent stress relaxation resistance as a terminal material for connectors of an automobile or the like and moreover having an excellent strength, elasticity, electrical conductivity, bendability, migration resistance, plating reliability or the like. SOLUTION: In a final stage after a slab of a copper base alloy contg., by weight, 0.1 to 10% Ni, 0.1 to 9% Sn, 0.001 to 0.30% P, and the balance Cu with inevitable impurities is, if required, subjected to a hot rolling, moreover subjected to a thermomechanical treating in which cold rolling and annealing are repeated and is subjected to rolling to a prescribed sheet thickness, the low temp. annealing is executed under a condition with a temp. higher than that in which a spring threshold value shows the maximum value, and 80 to <100% of the maximum value of the spring threshold value are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper-based alloy having excellent stress relaxation resistance.

[0002]

2. Description of the Related Art As the prior art of this kind, the following has been proposed. That is, Japanese Patent Publication No. Hei 8-9745 discloses that Ni: 0.5 to 3.0% and Sn: 0.
A copper-based alloy containing 5 to 2.0% and P: 0.05 to 0.20% and having a balance of Cu and unavoidable impurities has a Ni / P weight percentage ratio of 20 to 35. A part of Ni and P to which a relative amount in a range is added is Ni-
Having a structure which is a P-based compound and uniformly and finely precipitated in the matrix, the tensile strength is 50K.
A technique relating to a copper-based alloy having characteristics of gf / mm ² or more, a spring limit value of 40 Kgf / mm ² or more, a stress relaxation rate of 10% or less, and a conductivity of 30% IACS or more is disclosed.

Japanese Patent Application Laid-Open No. 4-154942 discloses that a slab of a copper-based alloy containing an appropriate amount of Ni, Sn, and P is subjected to a hot rolling step and a cold rolling step in which cold rolling and annealing are repeated. There is disclosed a technique of performing processing under specific conditions when rolling to a predetermined plate thickness.

[0004] In particular, in the final annealing, by applying a tension annealing treatment at a temperature of 300 to 750 ° C for 5 to 180 seconds, an improvement in spring limit value, stress relaxation resistance and recovery of ductility can be exhibited, and uniform and flatness can be obtained. A technique for obtaining a good product is disclosed.

[0005] Materials used for connectors of automobiles and the like include:
With the development of electronics in recent years, higher density, smaller size, lighter weight, and improved reliability have been required.

[0006] Further, as the performance of the engine has been further improved, the temperature in the engine room has been rising, and a copper-based alloy for connectors, which is a conductive material used therein, is required to have excellent stress relaxation resistance. It is becoming.

As a countermeasure, the above-mentioned Japanese Patent Publication No. 8-974
As described in Japanese Patent Application Laid-open No. 5 and JP-A-4-154942, a copper-based alloy containing Ni, Sn, and P having a specific composition and having excellent stress relaxation resistance has been proposed.

[0008] In the prior art, in order to use a copper-based alloy as a spring material, a condition that maximizes a spring limit value in low-temperature annealing after rolling to a final sheet thickness has been adopted. However, the inventors of the present application have studied the final low-temperature annealing in more detail, and have found that the stress relaxation resistance can be further improved as compared with a material obtained under the conventional low-temperature annealing conditions.

[0009]

SUMMARY OF THE INVENTION In view of the problems of the prior art, the present invention has extremely excellent stress relaxation resistance as a terminal material for connectors of automobiles and the like, and has strength, elasticity, and the like.
The present invention proposes a method for producing a copper-based alloy having excellent electrical conductivity, bending workability, migration resistance, plating reliability, and the like.

[0010]

SUMMARY OF THE INVENTION The present invention provides a method for producing N by weight percent.
i: 0.1 to 10%, Sn: 0.1 to 9%, P: 0.0
A copper-based alloy slab containing 0.01 to 0.30%, with the balance being Cu and unavoidable impurities, may be subjected to a hot rolling step and, if necessary, to a working heat treatment step in which cold rolling and annealing are repeated. In the final step after rolling to the sheet thickness of the copper-based alloy excellent in stress relaxation resistance characterized by performing the conditions of low-temperature annealing at a temperature higher than the low-temperature annealing temperature at which the spring limit value shows the maximum value It is intended to provide a manufacturing method.

[0011]

The copper-based alloy produced according to the present invention contains Ni: 0.1 to 10% and Sn: 0.1% by weight in Cu as described above.
-9%, P: 0.001-0.30%, and the manufacturing method thereof includes a hot rolling step from a slab of a copper-based alloy having the above-mentioned component composition, if necessary. In the manufacturing process of processing to a predetermined thickness through a thermomechanical treatment process in which cold rolling and annealing are repeated, the cooling conditions after hot rolling, the rolling reduction and the annealing conditions in the cold rolling process are appropriately controlled. By doing so, the Ni-P-based compound is finely and homogeneously dispersed in this manufacturing process, and excellent strength,
It has electrical conductivity, and the condition of low-temperature annealing in the final step is performed at a temperature higher than the low-temperature annealing temperature at which the spring limit value is the highest, and is 80% or more of the maximum value of the spring limit value.
%, A copper-based alloy exhibiting extremely excellent stress relaxation resistance can be obtained (see FIG. 2).

The relationship between the spring limit value and the stress relaxation rate of a Cu—Ni—Sn—P based copper alloy is closely related to the low-temperature annealing conditions, as shown in FIG. When performing low-temperature annealing for a certain period of time, the relationship between the spring limit value and the temperature is as follows: As the annealing temperature is increased, the spring limit value reaches a maximum value at a certain temperature, and when the temperature becomes higher, the spring limit value gradually increases. When the temperature exceeds 80% of the maximum value, the temperature rapidly decreases.

Although the stress relaxation rate can be reduced by increasing the annealing temperature, the stress relaxation rate increases when the temperature exceeds a certain temperature. The temperature at which the stress relaxation rate becomes minimum is on the higher temperature side than the temperature at which the spring limit value becomes maximum, and exists in a temperature range showing 80% or more and less than 100% of the maximum value of the spring limit value.

Until now, when manufacturing a copper alloy for a connector, the manufacturing conditions have been set so that the spring limit value has the highest value. On the other hand, in the present invention, since the low temperature annealing is performed at a higher temperature than the temperature at which the spring limit value is the highest value, the spring limit value is 80% or more and less than 100% of the maximum value, but the stress relaxation resistance is the most. It shows an excellent value (the lowest value of the stress relaxation rate).

Next, Cu-Ni-Sn in the method of the present invention is used.
The action of the added element of the -P-based copper-based alloy and the reason for limiting the component composition range will be described.

Ni forms a solid solution in a Cu matrix to improve stress relaxation resistance, and also improves strength, elasticity, and migration resistance. The effect is further enhanced by forming a compound with P and dispersing and precipitating. However, if Ni is less than 0.1%, the desired effect cannot be obtained, and if it exceeds 10%, the electric conductivity becomes extremely low, which is not practical. Preferably, it is in the range of 0.5 to 3.0%.

Sn forms a solid solution in a Cu matrix to improve strength, elasticity and corrosion resistance. However, Sn
If it is less than 0.1%, the desired effect cannot be obtained, and if it exceeds 9%, the electrical conductivity and migration resistance are significantly reduced, and the castability and hot workability are adversely affected. Preferably, it is in the range of 0.5 to 2.0%.

P acts as a deoxidizing agent for the molten metal and forms a compound with Ni to disperse and precipitate.
Improves stress relaxation resistance and improves strength, elasticity and electrical conductivity. However, when the P content is 0.
If it is less than 001%, the desired effect cannot be obtained, while 0.30%
%, The electrical conductivity and the weatherability of the solder decrease significantly,
It also has an adverse effect on castability and hot workability. Preferably,
The range is 0.005 to 0.20%.

Next, Cu-Ni-Sn in the method of the present invention is used.
The production conditions for the -P-based copper-based alloy will be described. In addition, Fe, Co, Ti, Mg, Zr, Ca, Si,
Mn, Cd, Al, Pb, Te, In, Ag, B, Y,
The production method of the present application is also effective for an alloy containing one or more of La, Cr, Ce, and Au in a total amount of 0.01 to 2%, and has a stress relaxation resistance property. Is improved, Fe, Co, Ti, Mg, Zr, Ca,
Si, Mn, Cd, Al, Pb, Te, In, Ag,
One or more of B, Y, La, Cr, Ce, and Au may be contained in a total amount of 0.01% to 2%.

In the hot rolling step, the ingot is heated to 750 ° C. or higher, and the hot rolling finish temperature is set to 650 ° C. or higher. If the hot rolling reduction at that time is 75% or more, the cast structure can be completely crushed, and the influence of segregation in the ingot can be eliminated.

In the cooling process after hot rolling, 3
Cool at a cooling rate of 50 ° C / min or more to 00 ° C or less,
It is important to obtain a hot-rolled material in which Ni, Sn, and P form a solid solution without precipitating the i-P compound.

Although it is preferable to perform hot rolling, it is possible to obtain a sheet material without using hot rolling. In cold rolling, a rolling reduction of 50% or more is required to homogenize the structure. Yes, then annealing at 400-600 ° C for 5-720
Process for a minute. By this treatment, Ni-P is contained in the copper-based alloy.
It is important to uniformly and finely disperse and precipitate the compound.

In the final rolling, to obtain strength and elasticity,
A rolling reduction of 0% or more is required.

It is important that the low-temperature annealing condition, which is the greatest feature of the method of the present invention, is performed at a temperature higher than the low-temperature annealing temperature at which the spring limit value is the highest value.
By setting the conditions to achieve 0% or more and less than 100%, a copper-based alloy having extremely excellent stress relaxation resistance can be manufactured.

The effect of the present invention can be applied to a solid solution strengthened copper alloy, for example, a copper alloy such as phosphor bronze in which Sn is dissolved.

Next, embodiments of the present invention will be described with reference to examples.

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLE An alloy having the composition shown in Table 1 was melted using a high-frequency melting furnace, heated to 850 ° C., hot-rolled to a thickness of 10.0 mm, and then cold-rolled and heat-treated repeatedly. The final working ratio was 50% and 67%, and a plate material having a plate thickness of 0.25 mm was obtained. Thereafter, low-temperature annealing was performed under each condition, and a spring limit value, Vickers hardness, and conductivity of the obtained material were measured, and a stress relaxation resistance was investigated. In the stress relaxation test, arch bending is performed so that the stress at the center of the test piece becomes 80% of the spring limit value, and the bending after holding at a temperature of 150 ° C. for 1000 hours is defined as a stress relaxation rate by the following equation. Was calculated by The results are shown in Table 1. Stress relaxation rate (%) = ｛(L ₁ −L ₂ ) / (L ₁ −
L ₀ ) × 100 L ₀ = Length of jig (mm) L ₁ = Length of sample before start of test (mm) L ₂ = Horizontal distance between sample ends after test (mm)

[0028]

[Table 1]

From the results in Table 1, it is found that Samples 1 to 5 according to the present invention were used.
The copper-based alloy of No. 5 has a spring limit value of 400 N / mm ^2.
As described above, the conductivity was 30% IACS or more, and the stress relaxation rate was about 1%, which was extremely excellent.

On the other hand, the as-rolled material No. No. 6 has a large stress relaxation rate and a small spring limit value. The low-temperature annealing condition is a condition in which the spring limit value indicates the maximum value or a condition on the lower temperature side. 7, No. 8 is inferior in stress relaxation rate to the material made by the method of the present invention.

If the condition of the low-temperature annealing is on the high-temperature side and the condition that the maximum value of the spring limit value cannot be attained is 80% or more, softening starts and is not practical.

Further, the alloy No. 1 which is out of the specified range of the alloy composition of the present invention. 9, No. 10, No. 11 is a case where Ni, Sn and P are insufficient, respectively, and in each case, the stress relaxation rate is remarkably inferior.

[0033]

According to the present invention, in a final step after rolling a slab to a predetermined thickness through a hot rolling step and a working heat treatment step in which cold rolling and annealing are further repeated, as the case may be, The condition of the low-temperature annealing is set to a temperature higher than the low-temperature annealing temperature at which the spring limit value has the maximum value, and the condition to achieve 80% or more and less than 100% of the maximum value of the spring limit value. It is possible to obtain a copper-based alloy having extremely excellent relaxation properties, and excellent strength, elasticity, and electric conductivity.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram showing a schematic manufacturing process of a copper-based alloy excellent in stress relaxation resistance according to the present invention.

FIG. 2 is a graph showing a relationship between a spring limit value and a stress relaxation rate under a low-temperature annealing condition (when the processing time is constant).

[Explanation of symbols]

 A: Annealing condition in the present invention B: Conventional annealing condition

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 683 C22F 1/00 683 685 685Z 686 686A 691 691B 694 694B

Claims (4)

[Claims] 1. Ni: 0.1 to 10% by weight, S
n: 0.1 to 9%, P: 0.001 to 0.30%, the balance being a hot-rolling step from a slab of a copper-based alloy consisting of Cu and unavoidable impurities, and further cooling In the final process after rolling to a predetermined thickness through a thermomechanical process that repeats cold rolling and annealing, the condition of low temperature annealing is performed at a temperature higher than the low temperature annealing temperature at which the spring limit value shows the maximum value. A method for producing a copper-based alloy having excellent stress relaxation resistance. 2. Ni: 0.1 to 10% by weight, S
n: 0.1 to 9%, P: 0.001 to 0.30%, the balance being a hot-rolling step from a slab of a copper-based alloy consisting of Cu and unavoidable impurities, and further cooling In the final step after rolling to a predetermined thickness through a thermomechanical treatment step of repeating cold rolling and annealing, the temperature condition of low temperature annealing is performed at a temperature higher than the low temperature annealing temperature at which the spring limit value indicates the maximum value, and the spring 80% to 100% of the maximum limit
A method for producing a copper-based alloy having excellent stress relaxation resistance, characterized by satisfying the condition of attaining less than. 3. Ni: 0.5 to 3.0% by weight, S
a hot-rolling step, if necessary, from a slab of a copper-based alloy containing n: 0.5 to 2.0, P: 0.005 to 0.20%, the balance being Cu and unavoidable impurities, and In the final step after rolling to a predetermined thickness through a thermomechanical processing step of repeating cold rolling and annealing, the condition of low temperature annealing is performed at a temperature higher than the low temperature annealing temperature at which the spring limit value indicates the maximum value. A method for producing a copper-based alloy having excellent stress relaxation resistance characteristics. 4. Ni: 0.5 to 3.0% by weight, S
a hot rolling step, if necessary, from a slab of a copper-based alloy containing n: 0.5 to 2.0, P: 0.005 to 0.20%, the balance being Cu and unavoidable impurities; Further, in the final step after rolling to a predetermined thickness through a thermomechanical processing step in which cold rolling and annealing are repeated, conditions for achieving low-temperature annealing at 80% or more and less than 100% of the maximum spring limit value. A method for producing a copper-based alloy having excellent stress relaxation resistance.