JP3050763B2 - Heat resistant automotive terminal materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant automotive terminal material having excellent stress relaxation resistance and migration resistance at high temperatures.

[0002]

2. Description of the Related Art Conventionally, brass strips excellent in formability (bending workability), spring characteristics and conductivity have been used for so-called terminal materials used as terminals or connectors used in connection parts of automobile wiring. Molded products were mainly used.

[0003]

However, in recent years, with the trend of miniaturization and weight reduction of electric parts for automobiles, further improvement of conventionally required characteristics such as formability, spring characteristics and conductivity has been required. Needless to say, as the performance of automobiles is further improved, the usage environment temperature is increased, and requirements such as anti-migration properties in an environment containing moisture tend to be more severe. That is, in recent years, reliability in particularly severe use environments has become more demanded, and it is often required that parts such as terminals and connectors are also required to withstand reliability evaluation at high temperatures up to 150 ° C. It is no longer possible to deal with conventional alloys such as brass.

[0004]

According to the present invention, as a result of various studies in view of the above points, a material for a heat-resistant automotive terminal having excellent stress relaxation resistance and migration resistance at high temperatures has been developed.

[0005] That is, the present invention provides a method for producing Zn: 28 to 37 wt.
%, Sn: a copper alloy containing 0.3 to 2.0 wt%, with the balance being substantially copper, wherein the content of the impurity element is:
Al: less than 50 ppm, Fe: less than 50 ppm, Ni:
A heat-resistant automotive terminal material characterized by having a content of less than 50 ppm and less than 50 ppm of P. The crystal grain size of the material is preferably in the range of 10 to 30 μm from the viewpoint of stress relaxation resistance at high temperature and bending workability.

[0006]

In the present invention, Zn as a main alloying element has an effect of increasing the formability and strength of copper as has been known for a long time, but if less than 28 wt%, the effect is insufficient. If it exceeds 37% by weight, the stress relaxation resistance decreases, and the rolling processability also deteriorates. Therefore, the Zn content is set to 28 to 37 wt%. Since Sn interacts with Zn and has an effect of improving the stress relaxation resistance and migration resistance of Cu-Zn alloy at high temperatures, it is a terminal material used in automobiles that are miniaturized and have higher performance. Is the most suitable additive element. Although the addition of Sn to improve the strength, corrosion resistance, etc. of brass is a conventionally known technique, the addition of Sn reduces the stress relaxation at high temperatures recently required for automotive terminal materials. The improvement in the characteristics and the anti-migration characteristics is a technical idea first clarified by the present invention. Here, the reason why the Sn content was limited within the range of 0.3 to 2.0% was that the Sn content was 0.3%.
If it is less than 2%, the effect is not sufficient, and the effect increases with an increase in the amount of addition. However, if it exceeds 2%, the effect is saturated, but the production yield is poor because the workability of the alloy is deteriorated. This is because it increases the cost of the material.

In the present invention, it is assumed that Zn and Sn are contained in predetermined amounts, and the balance is substantially Cu. Includes an element that does not substantially change its characteristics as an impurity ", and usually, an impurity of about 100 ppm is permissible. However, in the present invention, Al, Fe, N
As for i and P, if one or more of the elements exceeds 50 ppm, the above-described favorable interaction of Sn—Zn is inhibited, and only the stress relaxation property and the migration resistance property at high temperatures are deteriorated. Without
As a result of significantly impairing the rollability, it was found that there was a drawback that the cost of the material was increased. Therefore, Al, Fe, N
Both i and P contents are limited to 50 ppm or less. Furthermore, even if the alloy composition is within the range of the present invention, when the crystal grain size is less than 10 μm or more than 30 μm, the stress relaxation resistance at high temperatures is slightly reduced, so that the crystal grain size is in the range of 10 to 30 μm. Is particularly preferred. The shape of the heat-resistant automotive terminal material according to the present invention may be any of a plate, a strip, and a wire, and is not particularly limited. Is often done.

[0008]

Embodiments of the present invention will be described below.

Example 1 Alloy compositions shown in Tables 1 and 2 (Example N of the present invention)
o. 1-4) and the alloy compositions shown in Table 3 (Comparative Example N)
o. Nos. 1 to 17, conventional example Nos. The raw material blended in 1) was melted, formed into an ingot having a thickness of 100 mm, a width of 500 mm, and a length of 1000 mm by continuous casting, and cooled to room temperature. Thereafter, the ingot was reheated to 800 ° C. in a non-oxidizing atmosphere, taken out into the atmosphere, and hot-rolled to a thickness of 10 mm. Although the hot-rolling rise temperature was about 400 ° C., the temperature was then cooled to room temperature, the oxide scale on the surface was removed by cutting, and then cold-rolled to a thickness of 2 mm. At this time, those having poor rolling workability and marked edge cracking of the plate are referred to as “edge cracking” in Tables 1 to 3.
Are marked with “×” or “XX”. Subsequently, after trimming the edge of the strip, the temperature is 650 ° C. in a non-oxidizing atmosphere.
For 2 hours, further cold-rolled to a thickness of 0.5 mm, and then annealed at 700 ° C. in a non-oxidizing atmosphere, followed by finish rolling to a thickness of 0.25 mm. In addition, the crystal grain size of the strip after finish rolling was variously changed by changing the running speed of the strip in the furnace during the annealing during running.

With respect to the strip obtained in this manner, the grain size was measured, and the stress relaxation resistance and the migration resistance were evaluated by the following methods. The results are shown in Tables 1 to 3. [Stress relaxation resistance]: Japan Electronic Materials Industry Association Standard (E
MAS-3003). With a double-supported beam system, a maximum stress of 40% of the proof stress is applied, and 150 ° C
The stress relaxation rate after holding for 1000 hours was measured. [Migration resistance]: Two strips (length 50 mm) arranged at 1.0 mm intervals using a test apparatus shown in FIG. 2 and repeating 20 cycles of 20 ppm NaCl dropping for 5 minutes and drying cycle for 20 minutes. The maximum value of the leakage current (migration current) flowing therebetween was measured.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

As is clear from Tables 1 to 3, the present invention example No. Nos. 1 to 41 are all conventional example Nos. As compared with No. 1, it has excellent stress relaxation resistance and migration resistance at high temperatures, a stress relaxation rate of 65% or less, and a migration current of 0.25 A or less. Grain size is 10
Inventive Example No. within the range of 30 μm. 1-29, 3
1, 32, 37, and 38 are particularly excellent in stress relaxation resistance, and have a stress relaxation rate of 60% or less. On the other hand, Z
Comparative Example N in which the contents of n and Sn are less than the range of the present application
o. Comparative Examples Nos. 1, 2, 15, 16 and Zn in which the content of Zn was larger than the range of the present application. 17 are conventional example Nos. 1
It has the same stress relaxation resistance as that of Comparative Example No. No. 17 also has very poor rolling workability. Comparative Example No. in which the Sn content was higher than the range of the present application. No. 14 has good stress relaxation resistance but very poor rolling workability. Further, even when the contents of Zn and Sn are within the range of the present application, Comparative Example No. containing at least one of the impurity elements such as Al, Fe, Ni, and P at 50 ppm or more. All of Nos. 3 to 13 are significantly inferior in stress relaxation resistance and migration resistance as compared with the examples of the present invention, and have poor rolling workability.

[0014]

Example 2 Inventive Example No. 1 obtained in Example 1. 8, Comparative Example No. 13 and Conventional Example No. Except that the test temperature was changed within the range of 40 to 160 ° C. for the material 1
The stress relaxation resistance was evaluated in the same manner as in Example 1,
The result is shown in FIG. As is clear from FIG. In Comparative Example No. 8 at any temperature in the range of 40 to 160 ° C. 13 and Conventional Example No.
As compared with the strip material No. 1, the material is excellent in stress relaxation resistance, and the tendency is remarkable at higher temperatures.

[0015]

As described above, the heat-resistant automotive terminal material according to the present invention is excellent in stress relaxation resistance and migration resistance at high temperatures, and has industrially remarkable effects.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between a test temperature and a stress relaxation rate in an example of the present invention, a comparative example, and a conventional example.

FIG. 2 is an explanatory diagram showing a method for measuring a migration current.

Claims (2)

(57) [Claims] 1. Zn: 28-37 wt%, Sn: 0.3
A copper alloy containing about 2.0 wt% and the balance being substantially copper, wherein the content of the impurity element is Al: 50 ppm
, Fe: less than 50 ppm, Ni: less than 50 ppm,
P: less than 50 ppm, heat-resistant automotive terminal material. 2. The heat resistant automotive terminal material according to claim 1, wherein the crystal grain size is 10 to 30 μm.