JP3105392B2 - Manufacturing method of copper base alloy for connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a medium-strength and medium-conductive copper-based alloy suitable as a material for electric and electronic parts such as connectors.

[0002]

2. Description of the Related Art With the recent development of electronics,
The electrical wiring of various machines is becoming more complicated and highly integrated, and accordingly, the demand for copper products for electrical and electronic parts such as connectors is increasing.

[0003] Electric and electronic parts such as connectors include:
Further weight reduction, higher reliability, and lower cost are required, and in order to satisfy these requirements, the copper-based alloy material for connectors has been reduced in thickness and complicated. It is said that strength, elasticity, conductivity, and press formability must be good in order to be pressed into a shape.

Specifically, it is desired to improve the strength of the terminal such that it does not buckle during insertion or removal or bending, and the strength against crimping and holding of the electric wire.
It is preferable that the conductivity be N / mm ² or more, and that the conductivity be 39% IACS or more in order to suppress generation of Joule heat due to energization.

[0005] Further, the demand for press formability is becoming severer due to the miniaturization of terminals, and workability is required to satisfy a ratio R / t of the radius (R) of the bent portion to the thickness (t) of 1 or less. Furthermore, it is necessary to have excellent corrosion resistance and stress corrosion cracking resistance, and since the female terminal is subjected to a thermal load, it must also have excellent stress relaxation resistance.

Hitherto, brass and the like have been used as low-cost materials as connector materials, but they are inferior in terms of balance between strength and electrical conductivity, corrosion resistance, stress corrosion cracking resistance, stress relaxation resistance and the like. Was. As described above, an inexpensive alloy material for a connector which has the above-mentioned various properties simultaneously and has not been obtained.

Generally, electrical and electronic parts such as connectors are made of Sn.
Since plating is often performed, preliminary treatments such as degreasing and plating peeling are required in order to reuse press waste generated in the pressing process as a raw material for dissolution. When press waste is directly used as a raw material, the furnace wall is damaged in the process of burning (oxidizing) or evaporating the press oil, blowholes of the ingot are generated due to the absorption of hydrogen, and the yield is reduced. This was a factor of cost increase.

Further, in the conventional manufacturing process of a plated material, a manufacturing process of a material to be a base material and a surface treatment process such as Sn plating are performed independently of each other. There is still room for cost reduction.

[0009] In addition, the presence or absence of Cu base plating, the thickness, and the like are examined depending on the material of the base material. However, this is examined from the viewpoint of plating heat peeling. The characteristics required for the connector terminal, such as contact resistance, contact resistance, and spring property, have not been comprehensively studied. Therefore, the study of the optimal film thickness of Cu or Sn has been insufficient.

[0010]

SUMMARY OF THE INVENTION With the development of electronics, the present invention relates to a copper-based alloy having the above-mentioned various characteristics required for materials for electrical and electronic parts such as connectors, that is, strength, elasticity, and the like. An object of the present invention is to provide a method for producing a copper-based alloy for a connector having excellent conductivity, press formability, and the like.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the types of components to be added to copper have been extremely reduced, and components that are less expensive than copper materials have been added. Develop copper alloys for connectors that have excellent properties such as strength, elasticity, electrical conductivity, and press formability required for materials for manufacturing electrical and electronic components such as connectors by reducing costs. Was completed.

[0012] Still further, the present invention provides a method for producing a Sn surface-treated material of the present alloy in a more advantageous manner, while enabling the press waste of the alloy surface-treated with Sn to be directly reused as a raw material for melting. For the purpose of providing.

That is, according to the present invention, the content of the additional component element is as follows: Zn: 3.0 to 7.0% by weight, Sn: 0.2 to 1.0% by weight.
%, And their addition amounts satisfy the relationship represented by the following formula (1), and 1.0 ≦ 0.2X + Y ≦ 1.8 (1) [where X is the Zn addition amount (wt%) And Y is the amount of Sn added (wt%). ] A material obtained by using a copper-based alloy having a total of impurities of 0.2 wt% or less as a raw material, performing a heat treatment at a temperature of 350 to 750 ° C for 1 to 360 minutes, and then performing a cold working at a working ratio of 40% or more. 0.3 to 1.0 Cu underlayer on the surface
a copper for a connector, which is formed by forming a surface treatment layer of 0.5 μm and Sn on a Cu underlayer with a thickness of 0.5 to 2.0 μm, and then performing a heat treatment at a temperature of 100 to 280 ° C. for 1 to 180 minutes. A method for producing a base alloy is provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the amounts of Zn and Sn in the copper-based alloy of the present invention are based on the following.

Zn: Strength and elasticity are improved by adding Zn. Since it is less expensive than Cu, it is desirable to add a large amount thereof. However, if it exceeds 7% by weight, corrosion resistance, stress corrosion cracking resistance, conductivity and stress relaxation resistance deteriorate. Further, the plating property and the solderability are reduced. on the other hand,
If it is less than 3 wt%, the strength and elasticity are insufficient. Further Sn
When the scrap surface-treated as a raw material is used as a raw material, the amount of occluded hydrogen gas at the time of melting increases, and blowholes of the ingot are easily generated. Further, since there is little cheap Zn, it is economically disadvantageous. Therefore, Zn is set in the range of 3.0 to 7.0 wt%.

Sn: A small amount of Sn has an effect of improving mechanical properties such as strength and elasticity. Also, Sn
It is preferable to contain it as an additional element also from the viewpoint of reusing a material surface-treated with Sn such as a plating material. However, when the Sn content increases, the electrical conductivity sharply decreases, and the hot workability also decreases. Therefore, in order to secure a conductivity of 39% IACS, the content must be within a range not exceeding 1.0% by weight. Conversely, if the content is less than 0.2% by weight, the above effects cannot be obtained. The addition amount of Sn is 0.2-1.
It may be in the range of 0 wt%.

If the range of the components defined as described above is within the range not exceeding the solid solubility limit of Cu, an alloy having a uniform composition can be obtained, and the alloy is limited by the following formula (1). (The hatched portion shown in FIG. 1 is the composition range of the copper-based alloy of the present invention), Zn and Sn are added to Cu of the master alloy to have a tensile strength of 450 N / mm ² or more and a conductivity of 39 or more. % IACS
In addition, various characteristics required for the connector material, specifically, corrosion resistance, stress corrosion cracking resistance (the crack life in ammonia vapor is at least 10 times that of brass 1), stress relaxation resistance (1
A copper-based alloy that satisfies the relaxation rate at 20 to 150 ° C. of not more than half of one type of brass and the formability (no crack generation even in 90 ° W bending with R / t ≦ 1.0) can be produced. 1.0 ≦ 0.2X + Y ≦ 1.8 (1) [where X is the amount of Zn added (wt%) and Y is the amount of Sn added (wt%)]. Further, it is desirable that other impurities be as small as possible. In particular, Fe and Si, which are generally contained in small amounts, lower the conductivity and increase the variation in hardness during heat treatment with a small amount, and it becomes difficult to control the crystal grains during recrystallization. % Or less, more preferably 0.05 wt% or less,
5 wt% or less, more preferably 0.03 wt% or less.

When the total amount of impurities exceeds 0.2% by weight, besides the decrease in conductivity, a decrease in moldability due to the effect of impurities, an increase in contact resistance due to the effect of an oxide film, and a decrease in solderability are caused. Therefore, the total amount of impurities is set to 0.2% by weight or less because the yield and the characteristics are likely to vary in production.

Further, the copper alloy material of the present invention is used in an amount of 350 to 75.
After a heat treatment at a temperature of 0 ° C. for 1 to 360 minutes, a Cu underlayer of 0.3 to 1.
It has been found that when the surface is coated with 0 μm and Sn at a thickness of 0.5 to 2.0 μm and then heat-treated at a temperature of 100 to 280 ° C. for 1 to 180 minutes, the characteristics as a connector material are further improved.

In this case, in the annealing before the final cold working, press formability is improved by controlling the crystal grain size to 5 to 20 μm, but the processing temperature at this time is 350 to 750 ° C. If the temperature is lower than 350 ° C., the temperature required for recrystallization is too low, and the treatment time is long. Therefore, it is not economical. If the temperature exceeds 750 ° C., the crystal grains become coarse in a short time, Difficult to control.

The processing time is 1 to 360 minutes. This is because if the treatment time is too short, the control of the crystal grains by recrystallization is not sufficient, and if the treatment time is too long, the growth and coarsening of the crystal grains are likely to occur, and it is economically disadvantageous. The final cold working ratio is 40% or more. If it is less than 40%, improvement in strength, hardness and the like due to work hardening is not sufficient. However, if the working ratio is too large, the workability is reduced. Therefore, a more preferable range is 40 to 80%.

The material thus obtained is coated with a Cu underlayer of 0.3 to 1.0 μm and a Sn surface treatment coating of 0.5 to 2.0 μm as a surface treatment. 0.3 μm Cu underlayer
If it is less than 0.5, the effect of preventing the decrease in solderability and the increase in contact resistance due to diffusion and oxidation of Zn in the alloy to the surface treatment layer and the surface is small, and even if it exceeds 1.0 μm, the effect is saturated, It is also not economical. If the Sn surface-treated layer is less than 0.5 μm, the corrosion resistance, particularly the hydrogen sulfide resistance, is insufficient. If the Sn surface-treated layer exceeds 2.0 μm, the effect is saturated, which is economically disadvantageous.

Further, if these surface treatments are carried out by electroplating, it is preferable in terms of uniformity of film thickness and economy, and more preferably, reflow treatment is performed after the surface treatment in order to obtain gloss.

It has been found that heat treatment after these surface treatments can further improve characteristics such as whisker countermeasures. That is, the surface treatment material is used in an amount of 100 to 28.
By performing the heat treatment at a temperature of 0 ° C. for 1 to 180 minutes, the spring limit value and stress relaxation resistance of the material are improved, and whisker countermeasures can be realized. If the temperature is lower than 100 ° C., such an effect is not sufficient. If the temperature is higher than 280 ° C., contact resistance, solderability and workability are reduced due to diffusion and oxidation. If the heat treatment time is less than 1 minute, the effect is not sufficient, and
If the amount exceeds the above range, the above-mentioned characteristics decrease due to diffusion and oxidation, which is not economical. Hereinafter, the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.

[0025]

Example 1 Table 1 shows a copper-based alloy N having a chemical composition (wt%).
o. 1 to 11 were melted using a high-frequency induction melting furnace, and 40
It was cast into an ingot of × 40 × 150 (mm). However, the atmosphere during melting and casting was an Ar gas atmosphere. Immediately after casting, it was cooled with water, and cold rolling and annealing were repeated for each ingot, and cold rolled to a thickness of 0.6 mm.

Next, after heat treatment at a temperature of 450 ° C. for 30 minutes, water quenching was carried out, and the heat-treated material obtained by acid pickling was cold-rolled to a thickness of 0.25 mm to obtain a test material. The alloy No. 1 of the present invention shown in Table 1 was used. Impurities in Nos. 1 to 8 were each 0.2% by weight or less in total, and in particular, both Fe and Si were 0.05% by weight or less.

The hardness, tensile strength and electrical conductivity were measured using the test materials obtained as described above. The measurement methods are JIS Z 2244 and JIS Z 22
41, according to JIS H0505. In addition, bending workability was measured by a 90 ° W bending test (CES-M-0002-6,
R = 0.2 mm, rolling direction and vertical direction), and those with a good mountain surface at the center were evaluated as ○, those with wrinkles as Δ, and those with cracks as X, and evaluated. Table 1 also shows the results.

[0028]

[Table 1]

From the results shown in Table 1, it is found that N
o. Copper alloys Nos. 1 to 8 are excellent in balance between tensile strength and electrical conductivity, and have good bending workability. Therefore, these are copper alloys having extremely excellent properties as materials for electric and electronic parts such as connectors. In contrast, Zn
No. with high content 9, No. 9 with many Fe impurities 10,
No. 1 containing many Fe and Si impurities. No. 11 is inferior in electrical conductivity and bending workability.

[0030]

Example 2 Inventive alloy No. 1 shown in Table 1 of Example 1. 1
And one type of commercially available brass (C2600-EH, C2600-H
Material), hardness, tensile strength, spring limit, conductivity,
The stress corrosion cracking resistance and the heat resistance temperature were tested and measured. In this case, the measurement test of the hardness, the tensile strength and the electrical conductivity is the same measurement method as in Example 1, and the measurement of the spring limit value is performed according to JIS.
H 3130. The stress corrosion cracking time was determined by applying a bending stress of about 400 N / mm ² to
Exposure time in the desiccator containing the aqueous ammonia solution and the cracking time. The heat-resistant temperature was a temperature at which the hardness after heating and holding for 30 minutes was 90% of the initial hardness. The results thus obtained are also shown in Table 2.

[0031]

[Table 2]

From the results shown in Table 2, the copper-based alloy of the present invention has higher conductivity, stress corrosion cracking resistance, and heat resistance than brass, which is a conventional material for electric and electronic parts such as connectors. It can be seen that the property has been improved. Therefore, it is clear that the copper-based alloy of the present invention has excellent environmental resistance and reliability.

[0033]

Embodiment 3

[Table 3]

After preparing the alloy strip of the present invention having the composition shown in Table 3, the Cu base plating was 0.5 μm and the Sn plating was 1.1 μm.
After the μm application, a material punched out by press was prepared as a raw material for melting casting. The target composition in the casting is shown in Table 3, and press scrap as a raw material for melting is about 1 t, and the rest is adjusted with electric Cu and Zn to obtain six ingots of about 2 t. The components of the obtained ingot were almost the same as those shown in Table 3.

Three of the obtained ingots were obtained by heating raw press waste at 450 ° C. for 3 hours in the air, and the remaining three were not subjected to any treatment. It was used. Each ingot was rapidly melted, a 2t ingot was cast, and hot rolling, cold rolling, and annealing were repeated to finish to 0.25 mm. The total length of the material obtained in this way was inspected, the number of defects caused by blowholes of the ingot was counted, and the results were shown in Table 4.
It was shown to.

[0036]

[Table 4]

From the results shown in Table 4, it can be seen that the heat-treated press waste used in accordance with the method of the present invention was excellent without defects, whereas the product used without heat treatment had defects. It turns out that there is a problem in the yield.

[0038]

Example 4 Alloy N of the present invention obtained in Example 1
o. 1 is Cu under plating 0.5 μm, Sn plating 1.1
The characteristics of the heat-treated at 150 ° C. for 60 minutes after the application of the μm and those not heat-treated after the plating treatment were compared, and the results are shown in Table 5. However, the stress relaxation rate was calculated by the following equation as the stress relaxation rate after bending for 500 hours at a temperature of 150 ° C. in an arch shape so that the stress at the center of the test piece was 400 N / mm ² . .

Stress relaxation rate (%) = [(L ₁ -L ₂ ) /
(L ₁ −L ₀ )] × 100 L ₀ : length of jig (mm) L ₁ : length of sample before start (mm) L ₂ : horizontal distance between sample ends after treatment (mm)

[0040]

[Table 5]

From the results shown in Table 5, it was found that the material heat-treated by the method of the present invention after the plating treatment was superior in various properties to the material not subjected to the heat treatment and was suitable for connectors.

[0042]

As described above, the material obtained by the method of the present invention has a tensile strength,
Since it has excellent electrical resistance balance, moldability, environmental resistance, heat resistance, stress relaxation resistance retention, etc., it is the most suitable material for electrical and electronic parts such as brass, which is an inexpensive connector.

[Brief description of the drawings]

FIG. 1 is a distribution diagram showing a composition range of a copper-based alloy of the present invention.

Continued on the front page (72) Inventor Iku Tanabe 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Tetsuo Kato 206-1 Nunobikihara, Harihara-gun, Haibara-gun, Shizuoka Prefecture Yazaki Parts Co., Ltd. (72) Inventor Yukio Ota 206-1 Nunobikihara, Haibara-cho, Haibara-gun, Shizuoka Prefecture, Japan Inside (72) Inventor Naoki Kakuda 206-1 Nunobikihara, Haibara-cho, Haibara-gun, Shizuoka Prefecture, Yazaki Parts Corporation ( 56) References JP-A-1-162737 (JP, A) JP-A-1-268834 (JP, A) JP-A-61-284593 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 9/00-9/10 C22F 1/00-3/02

Claims (1)

(57) [Claims] 1. The content of an additional component element is Zn: 3.0 to 3.0.
7.0 wt%, Sn: 0.2 to 1.0 wt%, and their addition amounts satisfy the relationship represented by the following formula (1): 1.0 ≦ 0.2X + Y ≦ 1.8 (1) [However, X is the addition amount (wt%) of Zn, and Y is the addition amount (wt%) of Sn. ] Using a copper-based alloy having a total of impurities of 0.2 wt% or less as a raw material, heat-treating at a temperature of 350 to 750 ° C for 1 to 360 minutes, and then performing cold working at a working ratio of 40% or more. On the surface, a Cu base is formed as a surface treatment layer with a thickness of 0.3 to 1.0 μm and Sn on a Cu base with a thickness of 0.5 to 2.0 μm, and then at a temperature of 100 to 280 ° C. for 1 to 180 minutes. A method for producing a copper-based alloy for a connector, comprising: