JPH06184678A - Copper alloy for electrical parts - Google Patents

Abstract

PURPOSE:To obtain a copper alloy for electrical parts high in electric conductivity and strength, or high in spring critical value, good in fitness with Sn or solder and having corrosion resistance. CONSTITUTION:This is a copper alloy for electrical parts having a compsn. contg., by weight, >1.5 to 5% Zn, 0.2 to 2.5% Sn, 0.01 to <0.3% Fe and 0.005 to 0.4% P, and the balance Cu with inevitable impurities and having <=10mum grain size, and it satisfies various conditions suitable as the member for electrical parts. The control of the same crystalline structure is executed in such a manner that the grain size is regulated to >=10mum preferably to about >=20mum by process annealing, and it is subjected to working by about >=40% and is subjected to annealing before finish rolling to regulate the grain size into <=10mum. After the annealing, working is applied by about 5 to 50% in accordance with uses to obtain desired strength and workability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy suitable for terminals, connectors, bus bars such as automobile junction blocks, fuse materials for automobiles, conductive members such as lead frames and lead materials.

[0002]

2. Description of the Related Art Conventionally, phosphor bronze, low alloy copper, or brass has been used as a member for electric parts. The characteristics commonly required for these members are that they have high electric conductivity, high strength, or high spring limit value, and that they have no contact with Sn or solder.
It has corrosion resistance. With respect to these required characteristics, phosphor bronze, low alloy copper and brass each have the following drawbacks. That is, phosphor bronze has problems in electrical conductivity and oxidation resistance. Further, low alloy copper such as Fe-containing copper has a drawback that it is inferior in oxidation resistance among corrosion resistance and that it is difficult to manufacture because it requires an aging precipitation treatment. Further, in the case of a solid solution type alloy which is not subjected to precipitation treatment, the strength is insufficient. Furthermore, brass has problems in electrical conductivity, stress corrosion cracking resistance, and compatibility with Sn or solder.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is to improve the drawbacks of the conventional copper alloy and satisfy various conditions suitable as a member for electric parts. It is intended to provide.

[0004]

The present invention provides 1.5% by weight.
More than 5 wt% and less than 5 wt% Zn, 0.2 wt% to 2.5 wt% Sn, 0.01 wt% to less than 0.3 wt% Fe, 0.005 wt% to 0.4 wt% It is characterized by containing the following P, the balance being Cu and unavoidable impurities, and having a grain size of 10 μm or less, and having relatively high electric conductivity, strong strength, and high corrosion resistance. Is made possible by adjusting the alloy composition and the crystal structure.

Next, the reasons for limiting the alloy components constituting the present invention will be described. Zn content over 1.5% by weight 5% by weight
The reason for limiting the content to less than 1.5% by weight is that the oxidation resistance and migration resistance are not sufficient and the melt-casting property is inferior. This is because unsuitable results are brought about in electrical components such as fuse materials for use in busbars and terminals that carry high currents, and stress corrosion cracking resistance also deteriorates. The Sn content is limited to 0.2% by weight or more and 2.5% by weight or less because when it is less than 0.2% by weight, it forms a solid solution in copper and is represented by strength such as tensile strength and spring limit value. This is because the effect of Sn for improving the electric conductivity is not sufficient, and if it exceeds 2.5% by weight, the electric conductivity is lowered and the result is unsuitable for electric parts.

The Fe content is limited to 0.01% by weight or more and less than 0.3% by weight, and the effect of Fe to increase the strength at less than 0.01% by weight, or the effect of molten Sn or solder and copper alloy Fe gathers at the interface to lower the interfacial tension, and Sn
Alternatively, it is because the effect of Fe for improving the contact with the solder is not sufficient, and if it is 0.3% by weight or more, the conductivity is lowered and the workability is lowered.

The P content is limited to 0.005% by weight or more and 0.4% by weight or less. When it is less than 0.005% by weight, the workability is improved and a synergistic effect with Fe is exerted to improve the strength. Effect, improving castability, or S
This is because the effect of improving the contact with n or the solder is not sufficient, and if it exceeds 0.4% by weight, the conductivity decreases. It should be noted that the alloy of the present invention can be added to
The strength can be improved by further adding at least one of n and Zr in an amount of 0.05% by weight or more and 2% by weight or less, if necessary.

The crystal structure control is performed as follows. That is, in the intermediate annealing, the grain size is set to 10 μm or more, preferably 20 μm or more, then 40% or more of the work is added, and the annealing before finish rolling is performed to obtain the grain size of 10 μm.
Anneal to m or less. After annealing, 5 to 50% processing is added depending on the intended use to obtain desired strength and workability. If necessary, a low temperature annealing step may be added. Among these, the requirements for improving both strength and workability are:
The crystal grain size of the product is to be 10 μm or less. Examples will be shown below.

[0009]

Example 1 The alloys of the present invention, comparative alloys and conventional alloys shown in Table 1 were melted in a high frequency melting furnace under a charcoal coating using a graphite crucible and die-cast. Obtained 35
25m thick by chamfering an ingot of 90x150mm
m and hot rolled at 800 ° C. to a thickness of 12 mm. After both sides of this plate are cut to a thickness of 10 mm, cold rolling and annealing are repeated, and the annealing temperature is adjusted so that the grain size before final processing becomes the value shown in Table 1, and the final processing rate. Four
A test material having a plate thickness of 0.3 mm was manufactured at 0%.

[Table 1]

A test piece was cut out from this test material and the tensile strength, elongation and conductivity were measured. The spreadability of the solder was examined using eutectic solder as a representative in order to measure the non-melting property with the molten Sn or the solder. Paper polishing the surface of each alloy,
Flux (RMA type conforming to MIL) was applied, solder (0.13 g) was placed on the solder, and the solder was melted for 30 seconds in a 350 ° C. atmosphere, cooled, and its spread area was measured.

Further, in order to investigate the corrosion resistance, the following two kinds of tests were conducted. The first is a high temperature oxidation weight loss test. Three
# 100 on both sides of the sample cut into a size of 0x50mm
After polishing with 0 emery paper, 350 ℃ x 2H in air
Heated r. The produced oxide film was peeled off using 10% sulfuric acid and then weighed to determine the oxidation weight loss. The second is a stress corrosion cracking test. CuSO ₄ · 5H ₂ O 125g
/ L, (NH ₄ ) ₂ S0 ₄ 590g / l, NH ₄ OH 71m
20 kg load bending stress in Matson's liquid consisting of 1 / l
/ Mm ² was applied and held for 48 hours. Second of these results
Shown in the table. The mark "x" in the stress corrosion cracking test indicates that the sample broke during this period.

[Table 2]

As shown in Table 2, the alloy of the present invention is good in all of strength, conductivity, resistance to solder, and corrosion resistance, but the conventional alloy 6 (low alloy copper) has high strength. And oxidation loss, conventional alloy 7 (red copper) has strength, spreading area and stress corrosion cracking resistance, and conventional alloy 8 (brass) has conductivity, spreading area, stress corrosion cracking resistance and conventional alloy 9 (phosphor bronze) Indicates that the conductivity and the weight loss due to oxidation are inferior. Further, the comparative alloy 5 is inferior in strength to the alloy of the present invention.

[0013]

Example 2 For the alloys 2 and 3 of the present invention of Example 1 and the comparative alloy, the final processing rates were 20% and 30%,
Other manufacturing methods were also the same as in Example 1. The tensile strength and elongation of the obtained test material were measured. The results are shown in Table 3.

[Table 3]

[0014]

[Effect] As described above, the present invention is required to be a member for electric parts, has good compatibility with Sn or solder, has high electric conductivity, has high strength, and has corrosion resistance. The effect is that a copper alloy for electric parts that satisfies all of the above properties can be obtained.

Claims (1)

[Claims] 1. Z of more than 1.5% and less than 5% by weight.
n, 0.2 wt% or more and 2.5 wt% or less Sn, 0.0
1% by weight or more and less than 0.3% by weight of Fe, 0.005% by weight or more and 0.4% by weight or less of P are contained, the balance is Cu and unavoidable impurities, and the grain size is 10 μm or less. Copper alloy for electrical parts.