Metal treatment – Stock – Copper base
Patent
1995-08-09
1997-04-29
IP, Sikyin
Metal treatment
Stock
Copper base
420472, 420473, C22C 900
Patent
active
056245068
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIALLY APPLICABLE FIELD
The present invention relates to a copper alloy for use in electrical and electronic parts such as terminals and connectors and the like.
BACKGROUND OF THE TECHNIQUE
Conventionally, an iron-contained copper alloy (Cu-Fe-P-Zn alloy) in which Cu is added with Fe of 2.3 weight %, P of 0.03 weight % and Zn of 0.13 weight % is superior in conductivity, and is well known as a high strength copper alloy material for use in electrical and electronic parts which is superior in heat resistance (the official gazette of Japanese Patent Publication No. 52(1977)-20404).
The iron-contained copper alloy contains Fe over a solid solubility limit of Fe in Cu at a normal temperature. Accordingly, iron is contained as crystallized substances or precipitates in an ingot of the iron-contained copper alloy produced by a continuous casting or a semi-continuous casting.
Before the ingot of the conventional iron-contained copper alloy is hot worked, it is required to be homogenized by annealing at a temperature of 930.degree.-1050.degree. C. as a heat treatment before the hot working in order to make the crystallized or precipitated iron into solid solution.
Also, ingots of copper alloy such as the above mentioned iron-contained alloy and the like have a brittleness region in a range of 500.degree.-700.degree. C., and an high temperature elongation thereof in this temperature range is not greater than 6%. Further, if these copper alloys such as iron-contained copper alloy and the like contain S, S moves in a grain boundary to accelerate the brittleness.
Therefore, there is a problem that, if the ingot having residual stress not less than 10 kgf/mm.sup.2 held at the brittleness temperature range over 30 minutes in a homogenizing annealing process, cracking is apt to occur, further cracking in a hot rolling process is apt to occur.
In order to prevent these disadvantages, the ingot is heated at a high temperature increasing rate. However, in case of the ingot which is large-sized to the degree of 150 mm in thickness, 550 mm in width, 5000 mm in length, and 4 ton in weight, for example, it is difficult to pass through the brittleness temperature range at a high temperature increasing rate.
On the other hand, although it is effective to add Sn in order to improve a strength and a molding workability of the above mentioned iron-contained copper alloy, there is caused a problem that the addition of Sn accelerates the brittleness more.
Further, recent years, since the resistors of the integrated circuit, etc. are increased in the number of the electrodes and are required to be packaged in high density into the printed-circuit board with the requirement of a weight-lightening and a miniaturization of the electrical and electronic parts, a pitch between the electrodes is decreased from 1/10 inch (2.54 mm) to 1/20 inch (1.27 mm) or 1/30 inch (0.847 mm), and accordingly, a pitch between the terminal and the connector becomes narrow.
In this way, the pitch between the electrodes of the electrical and electronic parts becomes narrow, so that there is apt to be caused disadvantages in which ions is eluted into a water fitted between the electrodes due to a dew condensation or an entering of the water, the ionized metal element moves to the negative pole to be separated thereon, metal crystals grow in a dendrite form from the negative pole similar to a plating (an electrical separating), then the metal crystals reach to the positive pole to cause the short circuit. This is referred as a migration phenomenon. In case of the copper alloy for use in the electrical and electronic parts, the migration phenomenon of Cu is apt to occur. There is a problem that when this phenomenon occurs, the electrodes short-circuit with each other.
Further, there are many cases that the copper alloy for use in the electrical and electronic parts is normally formed by press punching (stamping) a strip material. Accordingly, an improvement of the service life (wear resistance) of the used metal tool turns out to be required from the cos
Kakuta Naoki
Kato Tetsuo
Ohota Yukio
Tsuzaki Yoshinobu
Ip Sikyin
Kabushiki Kaisha Kobe Seiko Sho
Yazaki -Corporation
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