Alloys or metallic compositions – Copper base – Tin containing
Reexamination Certificate
2000-08-15
2002-02-05
Ip, Sikyin (Department: 1742)
Alloys or metallic compositions
Copper base
Tin containing
C148S433000
Reexamination Certificate
active
06344171
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a copper alloy for electrical or electronic parts such as a terminal, a connector, a relay and a bus bar, and in particular to a copper alloy for electrical or electronic parts which has superior strength (yield strength), electric conductivity, spring limit value, resistance property of stress relaxation, bendability and Sn plating property.
2. Description of the Related Art
Electrical equipment for cars is increasing. In such a situation, the number of connectors is also increasing in wire harness for connecting a battery or a controller to various electrical parts, actuators, sensors or the like. It has been demanded to make the connectors compact. Connectors mounted near an engine section are always under high temperature and high vibration environment based on the engine section. When a large electric current is sent particularly to a connector for supplying electric power, the connector generates heat by itself so that the temperature thereof rises up to a higher temperature. Therefore, it has been demanded that such a connector (particularly, a female terminal) has high reliability under the above-mentioned environment (that is, looseness does not arise).
As a material of a copper alloy connector for conventional cars or the like, Cu—Fe—P alloys (CDA19400) or Cu—Mg—P alloys are known. The former alloys are alloys whose strength is improved by precipitation of Fe—P compounds based on co-addition of Fe and P. There are also known an alloy whose migration-resistance is improved by further addition of Zn (see JP-A-No. 1-168830); an alloy whose resistance property of stress relaxation is improved by addition of Mg (see JP-A-No. 4-358033); and the like. The latter alloys are alloys whose strength and thermal creep property are improved by addition of both of Mg and P so as to improve tensile strength, electric conductivity and resistance property of stress relaxation (JP-B-No. 1-54420).
In order to make wiring connectors (particularly, female terminals) for electrical parts for cars compact and keep their reliability (keeping their contact/press power), it is necessary to make the strength (yield strength) and the spring property (spring limit value) of the material of the connectors higher. In order that looseness is not caused (that is, fitting power does not drop by passage of time) even if the connectors are kept at high temperature for a long time, it is necessary to improve their resistance property of stress relaxation. At the same time, it is necessary that their electric conductivity is improved to suppress self generation of heat. Besides, it is demanded that the above-mentioned material has superior formability (particularly, bendability) in order to form small-sized connectors and this material has superior adhesiveness to Sn plating in order to decrease contact resistance between male and female terminals and improve corrosion resistance.
However, Cu—Fe—P copper alloys, which are conventional materials of connectors, are superior in formability, but have a problem that their spring limit value is low and their resistance property of stress relaxation is poor. In alloys wherein Mg is added to such alloys, their spring limit value is improved but their formability and electric conductivity are lowered. Cu—Mg—P copper alloys are superior in resistance property of stress relaxation but are poor in formability and adhesiveness to Sn plating.
SUMMARY OF THE INVENTION
In the light of such problems in the prior art, the present invention has been made. An object of the present invention is to provide a copper alloy for electrical or electronic parts which has superior yield strength, electric conductivity, spring limit value, resistance property of stress relaxation, bendability and Sn plating property.
The copper alloy for electrical or electronic parts of the present invention comprises Fe: 0.5-2.4% (“%” means “% by mass”, which is the same hereinafter.), Si: 0.02-0.1%, Mg: 0.01-0.2%, Sn: 0.01-0.7%, Zn: 0.01-0.2%, P: less than 0.03%, Ni: 0.03% or less, and Mn: 0.03% or less, and further comprises Cu and inevitable impurities as the balance of the alloy.
If necessary, the copper alloy for electrical or electronic parts of the present invention may comprise Pb: 0.0005-0.015%, and/or may comprises one or more of Be, Al, Ti, V, Cr, Co, Zr, Nb, Mo, Ag, In, Hf, Ta and B in their total amount of 1% or less.
The amount of each of Bi, As, Sb and S as the inevitable impurities of the copper alloy is set up to 0.003% or less, and the total amount of these impurities is set up to 0.005% or less from the viewpoint of the production of the copper alloy. From the viewpoint of the same, the amount of O is preferably limited to 10 ppm or less and the amount of H is preferably limited to 20 ppm or less.
The copper alloy for electrical or electronic parts according to the present invention has all of properties which are required for such electrical or electronic parts as a terminal, a connector, a relay and bus bar. The above-mentioned properties include strength (yield strength), electric conductivity, spring limit value, resistance property of stress relaxation, bendability, and Sn plating property. The copper alloy is especially suitable for wiring materials for cars and in particular for materials of small-sized connectors for supplying electric power.
In the copper alloy for electrical or electronic parts according to the present invention, Si, which has deoxidization effect, is added and the added amount of P, which blocks uniform recrystallization, is made as small as possible. Thus, the copper alloy can be produced at low costs and with high productivity.
DETAILED DESCRIPTION OF THE INVENTION
Components or composition of the copper alloy for electrical or electronic parts of the present invention will be described hereinafter.
Fe
Fe is precipitated in this copper alloy to improve its strength. However, if Fe is contained in an amount over 2.4%, coarse Fe grains are crystallized or precipitated to lower its bendability. On the other hand, if the amount is below 0.5%, Fe is not easily precipitated to lower the strength and the electric conductivity of the alloy. Moreover, grains of recrystallization grow so that cracks are easily generated upon bending. Therefore, the amount of Fe is set up to 0.5-2.4% and preferably 1.0-2.1%. Within this range, the yield strength and the resistance property of stress relaxation of the alloy are further improved. The amount of Fe is more preferably from 1.8 to 2.0%. Within this range, the effect of suppressing the generation of cracks upon hot-rolling is improved.
Si
Si causes the copper alloy to be deoxidized instead of conventional P (both of Fe and Si contribute to deoxidization). Si has the effect of suppressing recrystallization-blocking-effect of P to promote uniform and fine recrystallization if the amount of P is below 0.03%. Si also has the effect of improving the resistance property of stress relaxation and the spring limit value of the alloy without lowering the electric conductivity thereof very much. If the amount of Si is below 0.02%, these effects are not sufficiently exhibited. On the otherhand, if the amount of Si is over 0.1%, the bendability deteriorates. The amount of Si is therefore from 0.02 to 0.1% and preferably from 0.03 to 0.07%. Within this range, the resistance property of stress relaxation of the alloy is further improved.
Mg
If Mg and solid-solution Sn are co-added to the copper alloy, Mg has the effect of improving its resistance property of stress relaxation and its spring limit value. However, Mg is easily oxidized. If the amount of Mg is large, melting in the atmosphere becomes difficult to lower the electrical conductivity of the alloy. For these reasons, in the copper alloy, Si compensates for a part of effects of Mg and Sn. If the amount of Mg is over 0.2% in the copper alloy (Cu—Fe alloy), uniform recrystallization is blocked so that the bendability of the copper alloy deteriorates. Above all, the resistance property of str
(Kobe Steel, Ltd.)
Ip Sikyin
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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