JPH0830235B2 - Copper alloy for conductive spring - Google Patents

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 conductive springs used in terminals, connectors, relays, switches and the like.

[0002]

2. Description of the Related Art Heretofore, brass and phosphor bronze have been widely used as these copper alloys for springs, and titanium copper and beryllium copper have been used for those partially required to have high strength.

[0003]

In recent years, due to the miniaturization of equipment and parts, materials having high strength and spring characteristics have been demanded, and particularly from the viewpoint of long-term reliability of spring characteristics, materials having good stress relaxation characteristics. Is required. Further, in order to improve the stress relaxation characteristic, it is necessary to prevent the temperature rise of the parts during use as much as possible, and therefore, a material having a good heat dissipation property, that is, a high electric conductivity is required.

Further, there is a demand for a highly reliable material which has good heat-resistant peeling property of Sn plating and solder plating and which does not cause a migration phenomenon in the presence of water. In contrast to these required properties, brass is low in cost, but inferior in strength and spring property, and has high susceptibility to stress corrosion cracking. Further, phosphor bronze and titanium copper have low electric conductivity, and beryllium copper is expensive, and each has its advantages and disadvantages.

In view of this, many alloys have been proposed in recent years, and among them, Cu-Ni-Si type alloys are attracting attention because they are excellent in strength and conductivity. Especially USP459
As shown in 4221 (Japanese Patent Laid-Open No. 61-250134), the addition of Mg further improves the stress relaxation characteristics, and is therefore a suitable spring material. However, it has been known that the present alloy significantly deteriorates the heat-resistant peeling property of the plating by adding Mg, and an improvement has been demanded.

[0006]

In view of such a situation, Cu
As a result of conducting a study on a -Ni-Si-Mg alloy,
As a spring material, an alloy satisfying all properties has been obtained.

That is, according to the present invention, Ni: 0.5-4.
0%, Si: 0.1 to 1.0%, Mg: 0.01 to 0.
1%, Zn: 0.01 to 15%, S: 0.0015% or less, O: 0.0015% or less, the balance is a copper alloy consisting of Cu, or P, B, As, Fe, Co, C in addition to the above.
r, Al, Sn, Ti, Zr, In, copper alloy containing 0.005 to 1.0% one or more of Mn
It is a conductive spring alloy.

The reasons for limiting the components of the alloy of the present invention are shown below. The reason for setting the Ni content to 0.5 to 4.0% is that Ni is
Produces an intermetallic compound with Si by aging treatment,
This is because it is a main component that improves both conductivity, but if it is less than 0.5%, the strength is low, and if it exceeds 4.0%, the workability is deteriorated.

Si has the effect of improving the migration resistance as well as the effect of improving the strength together with Ni without significantly lowering the conductivity, but its content is 0.1 to 1.
The reason for setting it to 0% is that those effects are not exhibited if it is less than 0.1%, and the conductivity is remarkably lowered if it exceeds 1.0%.

The reason for setting the Mg content to 0.01 to 0.1% is that Mg improves the stress relaxation characteristics but deteriorates the heat-resistant peelability of the plating. This is because even if O is specified, the stress relaxation property cannot be improved, and if it exceeds 0.1%, the heat-resistant peeling property of the plating decreases.

The reason for setting the S content to 0.0015% or less is that the Mg content should be low and the S content should be extremely high in order to improve the heat-resistant peeling property of the plating and to improve the stress relaxation characteristics. This is because it was found that when S exceeds 0.0015%, a large amount of Mg becomes a sulfide and is dispersed in the material, and not only the stress relaxation characteristics are not improved, This is because, even if the Mg content is low, the heat-resistant peeling property of the plating deteriorates, and when the plated product is heated, defects such as swelling and blistering will occur. The reason for setting the O content to 0.0015% or less is exactly the same as that for S. Not only the Mg becomes an oxide, the stress relaxation property is not improved, but also the heat-resistant peeling property of the plating is deteriorated and the plated product is This is because when heated, defects such as stains and swelling occur.

That is, the contents of S and O are both 0.0
By setting the content to 015% or less, the stress relaxation property can be improved even if the Mg content is lowered, and the heat peeling resistance of the plating can be improved by lowering the Mg content.

Further, it has been found that the regulation of the contents of S and O is a key point in order to prevent the heat-resistant peeling property of the plating and the stain and swelling of the plating even with a small amount of Mg.

The content of P, B and other subcomponents is 0.00
The reason for setting it to 5 to 1.0% is that the addition of a subcomponent improves the strength, but if it is less than 0.005%, it has no effect and
This is because if it exceeds%, the workability is lowered and the conductivity is remarkably lowered.

The reason for setting the Zn content to 0.01 to 15% is that the addition of Zn improves the heat-resistant peeling property of the plating, improves the migration resistance, and reduces the cost. This is because if it is less than 0.01%, the effect is not obtained, and if it exceeds 15%, the sensitivity to stress corrosion cracking is rapidly increased.

[0016]

EXAMPLES Next, examples and comparative examples will be described.
Table 1 shows the composition of the tested copper alloys. Copper alloys with these compositions are melt-cast in the atmosphere, and 30 mmt x 60 m
An ingot having a size of mw × 120 ml was obtained. These ingots were chamfered on one side by 3 mm to mechanically remove surface defects, then heated at a temperature of 800 to 950 ° C. for 2 hours and then hot-rolled to a thickness of 6 mmt. After pickling to remove surface scale, cold rolling was performed to a thickness of 0.5 mmt. After that, water quenching was performed after solution treatment for 5 to 10 minutes at a temperature of 800 to 900 ° C. The grain size after the solution treatment was adjusted to 10 μm. And 0.3 mmt
After finishing cold rolling up to 1 ~ at a temperature of 400-500 ° C
Aging treatment for ~ 7 hours under the condition that maximum strength is obtained,
Finally, the surface was polished with # 1200 emery paper to remove surface defects such as scales, and used as a test material.

[0017]

[Table 1]

About the test materials, tensile strength, elongation, conductivity,
Stress relaxation characteristics, heat resistance peeling property of tin plating, silver plating property and stress corrosion cracking resistance were tested. JIS13 for tensile strength and elongation
A B tensile test piece was used to perform a tensile test for measurement. The electrical conductivity was converted into electrical conductivity by processing the test piece of 10 mmw × 100 ml and measuring the electrical resistance at 20 ° C. by the four-terminal method. The stress relaxation characteristics are as shown in Fig. 1 for a test piece with a plate thickness of 0.3 mm processed into 10 mmw x 100 mml, and a gauge length l = 50 mm.
Bending stress of height y ₀ = 20 mm at 80 ° C. and permanent deformation amount (height) shown in FIG. 2 after heating at 150 ° C. for 1000 hours
Stress relaxation rate {[y (mm) / y ₀ (mm)]
× 100 (%)} was calculated. The tin-plating heat-resistant peeling property is obtained by applying a copper undercoat of 0.5 to 0.8 μm to the test material,
About 1-1.5 μm tin electroplated and then heated and reflow treated, cut into 10 mmw × 100 mml and then heated at 150 ° C. for a predetermined time (every 100 hours), with a bending radius of 0.3 mm (= plate thickness) on one side 90 ° bending was performed once reciprocatingly, and the vicinity of the bent portions on the front and back surfaces was observed in a field of view of 20 times to confirm the presence or absence of peeling of the plating. The silver plating property is 1470 mm ² (7 m after heating at 450 ° C. for 2 minutes for the test material on which copper flash plating is applied as a base and silver plating is applied to 1 μm.
The number of blisters was measured for the area of m □ × 30).
The stress corrosion cracking resistance is 12.5 mmw × 150 mml, and the test material is left indoors for 12 hours while being fixed in a loop, and then left in a desiccator with a volume of 10 liters containing 2 liters of 14% ammonia water, The presence or absence of cracks was visually inspected and evaluated by the time until cracks occurred. As for migration resistance, the test material is 10 mmw x 100 mml.
Then, as shown in FIG. 3, two sheets were set as a set and immersed in tap water (300 ml) as shown in FIG. Next, a DC voltage of 14 V was applied between these two test materials, and the change in current value with respect to the elapsed time was measured. A representative example of this result is shown in FIG.
Shown in The migration resistance was evaluated by the time until the current value reached 1.0 A (arrow in FIG. 5). The results of these evaluations are shown in Table 2.

[0019]

[Table 2]

From this table, the alloy of the present invention has good strength and conductivity, good stress relaxation property, very good surface quality such as heat resistance peeling property of tin plating and silver plating property, and stress resistance. It can be seen that the corrosion cracking property is also good.

Contrary to these, No.
7 has a high Ni content, so the strength is high but the elongation is low,
Workability is not very good. No. Since No. 8 has a high Si content and S content, it has low conductivity, poor stress relaxation characteristics, and poor surface quality such as heat resistance peeling property of tin plating and silver plating property.
No. No. 9 is an example in which the amount of Mg is low and the amount of Zn is high.
Since the g content is low, the stress relaxation characteristics are not very good, and Z
Since the amount of n is large, the conductivity is low and the stress corrosion cracking resistance is poor. No. Although 10 and 12 are examples in which the amount of Mg is large, the stress relaxation characteristics are good, but the heat resistance peeling resistance of tin plating is poor. N
o. Since No. 11 has a low Ni content and a high O (oxygen) content, sufficient strength cannot be obtained, and stress relaxation characteristics, heat resistance peeling property of tin plating, and silver plating property are poor.

No. Since No. 13 has a large amount of S and Zn, the stress relaxation property, silver plating property, and stress corrosion cracking resistance are poor. N
o. No. 14 is an example in which Mg is not added, but the stress relaxation characteristic is not so good.

No. Since No. 15 has a large amount of O and S, the stress relaxation property, the heat resistance peeling property of tin plating, and the silver plating property are poor. N
o. Since No. 16 has a small amount of Si, sufficient strength cannot be obtained and migration resistance is also poor.

As explained above, the alloy of the present invention is Cu-N.
It defines the O and S contents of the i-Si-Mg- Zn alloy, and further defines P, B, As, Fe, Co, Cr, Al, Sn and T.
By adding one or more of i, Zr, In, and Mn, high strength, high conductivity, good stress relaxation characteristics, good heat resistance peeling property and good silver plating property, and stress corrosion cracking resistance. Is also good,

[0025]

INDUSTRIAL APPLICABILITY The alloy of the present invention is a copper alloy having high strength, high electrical conductivity, stress relaxation property, plating heat-resistant peeling property, silver plating property, and stress corrosion cracking resistance, and is widely used in connectors, relays, switches, etc. It is a copper alloy that should be used in the field of parts.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a stress relaxation characteristic test method.

FIG. 2 is an explanatory diagram of a permanent deformation amount in a stress relaxation characteristic test.

FIG. 3 is an explanatory diagram of a test material for a migration resistance test.

FIG. 4 is an explanatory diagram of a migration resistance test.

FIG. 5 is a graph showing changes in current value field with respect to elapsed time in a migration resistance test.

Claims (2)

[Claims] 1. Ni: 0.5-4.0% (wt%, below
The same) , Si: 0.1 to 1.0%, Mg: 0.01 to
0.1%, Zn: 0.01 to 15%, S: 0.0015
% Or less, O: 0.0015% or less, and the balance Cu, a copper alloy for conductive springs. 2. Ni: 0.5 to 4.0%, Si: 0.1
~ 1.0%, Mg: 0.01-0.1%, Zn: 0.0
1 to 15%, S: 0.0015% or less, O: 0.001
5% or less, and P, B, As, Fe, C as auxiliary components
Of o, Cr, Al, Sn, Ti, Zr, In and Mn
A conductive copper alloy for springs , which contains 0.005 to 1.0% of one kind or two or more kinds and the balance is Cu.