JPS6312930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a conductive copper alloy having excellent spring properties and a method for producing the same. For example, phosphor bronze has been widely used as a conductive material that requires spring characteristics, such as terminal fittings for electrical circuit connections, springs for electronic and electrical equipment parts, and lead frames for integrated circuits (for example, JIS H3731, JIS H3732). In recent years, the reliability required for electrical circuits and electronic equipment parts has become more and more stringent, and the materials for these materials are also required to have even higher characteristics as described below. (b) For example, it is necessary that the material does not break or cause roughening of the surface of the bent portion, even when subjected to severe bending in the process of processing a strip of material into a complex-shaped terminal fitting, etc. (b) Phosphor bronze has an angle of about 200° to improve spring characteristics.
It is often used after being subjected to so-called low-temperature annealing treatment at 250℃ for about one hour, but there is a demand for expanding the range of heating conditions suitable for this heat treatment so that high properties can be obtained industrially and stably. . (c) It is also desirable that even if heated during use, deterioration of spring characteristics and stress relaxation due to creep are unlikely to occur. (iv) Furthermore, when the material is used for applications such as lead frames for integrated circuits, the surface is plated with silver, but if the surface condition of the material is not good, this plating characteristic will be adversely affected. The thing that most likely affects this surface condition is scratches during hot working, but phosphor bronze is not a material that inherently has very good hot workability. From this point of view, there is a strong demand for improving the hot workability of phosphor bronze. The present invention has been made to meet the above-mentioned requirements, and has excellent bending workability, high properties can be easily obtained by low-temperature annealing, and has a small amount of creep during use, and also has problems in hot workability. It is an object of the present invention to provide a copper alloy having excellent spring properties with a small amount of spring and a suitable method for manufacturing the same. In the present invention, Sn3.0 to 12.0% by weight (hereinafter simply %
), P0.002~0.4%, and Zr0.03~0.09%, the remainder being essentially copper, and its production method is based on the copper alloy described above. After the ingot has been hot worked, it has been cold worked and intermediate annealed at least once each, and then cold worked to a working degree of 10% or more, and then
This is a method for producing a conductive copper alloy, which is characterized by performing low-temperature annealing at a temperature of 200° to 330°C for 10 minutes to 10 hours. In the present invention, Sn3.0~12.0%, P0.002~0.4
% because less than 3.0% Sn or 0.002% P is insufficient in terms of spring characteristics, strength, etc.
Furthermore, even if Sn exceeds 12.0% or P exceeds 0.4%, the processability, heat and electrical conductivity will be unnecessarily impaired, and there will be little effect on improving the properties. Also, the Zr amount was specified as 0.03% to 0.09%.
If it is less than 0.09%, the property improvement effect will not be sufficient compared to conventional phosphor bronze, and even if it is added more than 0.09%, it will be difficult to obtain a uniform alloy composition, or the deformation resistance will increase too much, resulting in poor workability. This is because manufacturing problems may occur, such as damage to the material, or difficulty in softening the material unless it is at a high temperature in the intermediate softening step that is often performed during the manufacturing process of strips and wires. The effect of adding Zr in the present invention is that it first prevents the crystal grains of the ingot from becoming coarse, and even if hot working is performed, the grains become coarse during heating and This has the effect of reducing defects. Therefore, the crystal grains of the material strip to be processed into terminal fittings etc. are fine, it has excellent bending workability, and it is less prone to cracking during hot processing.
It can also be expected to improve yield and product surface characteristics. Furthermore, when used for springs, low-temperature annealing is often performed to improve spring properties.
In this case, the addition of Zr has the advantage of widening the range of low-temperature annealing conditions for obtaining high spring properties and making it possible to industrially easily supply products with excellent spring properties. Furthermore, since creep resistance is improved by adding Zr, stress relaxation is less likely to occur when used in applications such as terminal fittings, and excellent connection characteristics are maintained. Another major feature of the addition of Zr in the present invention is that it hardly impedes the thermal and electrical conductivity required for electronic equipment and parts for electrical equipment. Next, the manufacturing method of the present invention will be explained. Conventional phosphor bronze has poor hot workability, so manufacturing methods that do not involve hot working are sometimes adopted, but the above-mentioned alloy of the present invention has improved hot workability. In order to destroy the cast structure and obtain a fine and uniform structure, it is preferable to perform hot working, and after the desired size and shape are approximated by at least one or more cold working and intermediate annealing treatment, It is desirable to perform cold working at a working degree of 10% or more, and if this working degree is smaller than this, the springiness and strength of the product are likely to be insufficient. In addition, low-temperature annealing at 200° to 330°C for 10 minutes to 10 hours is not sufficient if the temperature is less than 200°C, and if the temperature exceeds 330°C, the tensile strength and yield strength may deteriorate. This is because it decreases. Furthermore, if the annealing time is less than 10 minutes, there will be little contribution to the effect of improving the spring properties, and if the annealing time is longer than 10 hours, it will not lead to any particular improvement in the properties and is meaningless from the perspective of energy saving. be. On the other hand, conventional phosphor bronze can only be annealed at temperatures up to 275° C., and temperatures higher than that result in disadvantages such as a decrease in strength. In such phosphor bronze, the improvement in spring properties due to low-temperature annealing is often most noticeable under conditions at the very edge of softening, but it has been difficult to aim for such conditions industrially. However, even if the alloy of the present invention is annealed at a low temperature under temperature conditions where the spring properties are sufficiently improved, there is little decrease in strength, so it has the effect that high properties can be stably obtained over a wide temperature range. Examples of the present invention will be described below. Example An alloy having the composition shown in Table 1 was melted in a regular electrical copper ingot under charcoal coating, and the alloying elements were added to the molten metal as Cu-15% P master alloy, Sn simple substance, and Cu-15% Zr master alloy. The ingot was melted using an alloy, cast into an 80 mm mold, the surface of the ingot was lightly cut, and the ingot was extruded at approximately 780°C to a width of 50 mm and a thickness of 10 mm. After surface peeling, this strip is cold-rolled at approximately 400°C.
An intermediate material with a thickness of 0.88 mm was obtained by repeating the intermediate softening treatment, and after performing intermediate softening, it was cold rolled (final working rate 60%) to a thickness of 0.35 mm. Table 1 shows the properties of the cold-rolled workpiece with a thickness of 0.35 mm and the workpiece that was subjected to low-temperature annealing at 270°C for 1 hour. The brass in Conventional Example No. 8 is a commercially available material, but the thickness is 0.88
Processing after mm was performed by almost the same process as described above. The properties shown in Table 1 are based on samples taken in a direction parallel to the rolling direction of the processed material. From the table, alloys Nos. 1 to 4 of the present invention are as cold rolled as conventional phosphor bronze No. 1 in terms of spring properties.
Although there is not much difference between No. 6 and No. 7, it can be seen that low-temperature annealing has the effect of greatly improving the spring properties without causing a decrease in tensile strength. Furthermore, the electrical conductivity of the alloy of the present invention after low-temperature annealing shows almost no decrease as compared to conventional phosphor bronze due to the addition of Zr, and it can be seen that the alloy has no inferiority in terms of thermal and electrical conductivity.

[Table] Note that Comparative Example No. 5, which has a low Zr content, does not have sufficient spring characteristics. Next, the surface condition of the strip after hot extrusion during processing of the alloy shown in Table 1 is as shown in Table 2.

[Table] From Table 2, it can be seen that alloys No. 1 to 4 of the present invention have improved hot workability compared to conventional phosphor bronze, and are required to improve yield and surface properties in industrial manufacturing processes. It can be expected that there will be advantages in application to various uses. Note that Comparative Example No. 5, which has a low Zr content, does not have a sufficient effect of improving hot workability. Next, the cold-rolled processed material samples shown in Table 1 were aligned along a jig with a radius of curvature of 0.2 mm.
The surface condition of the outside of the bent part when bent 180 degrees, the results of repeatedly bending the same curvature by 90 degrees left and right alternately, and measuring the number of times it takes to break (90 degrees bending is one time), and the results of each sample. The crystal grain size measurement results are shown in Table 3. Note that the repeated bending test was performed on samples parallel and perpendicular to the rolling direction of the processed material. From Table 3, it can be seen that alloys Nos. 1 to 4 of the present invention have good bending workability and less directionality. This seems to be related to the fact that the crystal grains of the alloy of the present invention are smaller and more refined than those of conventional alloys. Next, when materials with such spring properties are used for terminal fittings, etc., creep resistance is required to prevent stress relaxation. After 10 hours of loading at 120℃ with a maximum load stress of 15Kg/ ^mm2 for the sample

[Table] The results of measuring the bending creep strain are shown in Table 4. From Table 4, it can be seen that alloys Nos. 1 to 4 of the present invention are all superior in creep resistance compared to the conventional example and the comparative example.

【table】

[Table] Next, regarding the present invention alloys No. 2 and 4 and the conventional example alloy No. 7 shown in Table 1, the thickness of the intermediate material was 0.38, 0.58,
The materials were intermediately softened at 0.88 and 1.75 mm, respectively, and then cold rolled to a thickness of 0.35 mm (working degrees: 9, 40, 60, and 80%), and these processed materials were rolled at various temperatures shown in Table 5. Table 5 shows the results of measuring the tensile strength and spring limit value after low-temperature annealing for hours.
As shown. From Table 5, Nos. 2 and 4 of the alloys of the present invention are the same as those of the conventional example.
7, a wide range of low-temperature annealing temperature conditions (235° to 325°
°C) with good spring properties without compromising strength.
It turns out that it is easy to obtain. However, in the conventional example, this temperature range is 235° to 280°C, and the spring characteristics are poor. Therefore, it is desirable that the alloy of the present invention be annealed at a low temperature in the temperature range of 200° to 330°C. Regarding the final degree of cold work before low-temperature annealing in the alloy of the present invention, the properties after low-temperature annealing are better when the degree of final cold work is about 10% or more. As mentioned above, the alloy of the present invention has Sn3.0~
12.0%, P0.002~0.4%, and Zr 0.03~0.09%
Zr
The addition of phosphor bronze refines the crystal grains and improves hot workability, without impairing the thermal and electrical conductivity of conventional phosphor bronze.

[Table] It is easy to manufacture products with excellent bending workability and spring properties, and there is little stress relaxation due to creep, so products that require excellent spring properties, such as terminal fittings, conductive spring materials, and lead frames. It has the advantage of providing an optimal material for a wide range of applications in electronic and electrical equipment components such as. Furthermore, improvement in hot workability is expected to improve yield and product surface characteristics, and has the advantage of making it possible to economically manufacture products with excellent characteristics. In addition, the manufacturing method of the present invention includes, as described above, hot working the alloy ingot of the present invention, followed by cold working and intermediate annealing treatment, and then cold working with a working degree of 10% or more, Furthermore, by performing low-temperature annealing at a temperature of 200° to 330°C for 10 minutes to 10 hours, excellent spring properties can be obtained without compromising strength or conductivity. Since a wider temperature range can be tolerated, products with high properties can be manufactured industrially stably and easily, providing an optimal manufacturing method for the alloy of the present invention.

Claims (1)

[Claims] 1. A conductive copper containing 3.0 to 12.0% by weight of Sn, 0.002 to 0.4% by weight of P, and 0.03 to 0.09% by weight of Zr, with the balance essentially consisting of copper. alloy. 2 After hot working a copper alloy ingot containing 3.0 to 12.0% by weight of Sn, 0.002 to 0.4% by weight of P, and 0.03 to 0.09% by weight of Zr, with the remainder consisting essentially of copper,
After passing through at least one cold working and intermediate annealing treatment, cold working with a working degree of 10% or more is performed, and further low temperature annealing is performed at a temperature of 200° to 330°C for 10 minutes to 10 hours. Characteristic manufacturing method of conductive copper alloy.