JPH0453945B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to the production of high-strength copper alloys for terminals and connectors of electrical and electronic components, which have excellent strength, elasticity, and electrical conductivity, as well as bending workability, plating reliability, and stress relaxation properties. Regarding the law. [Prior Art and Background of the Invention] Materials for terminals and connectors that make up the conductive terminals on the plug side and the socket side have various characteristics such as strength, elasticity, stress relaxation properties, and corrosion resistance, regardless of their shape and size. In addition to having these characteristics, it is required that the material be easy to process and inexpensive. Brass and phosphor bronze are the most commonly used materials for such terminals and connectors. Brass has the advantage of being easy to mold and inexpensive, but it has poor corrosion resistance and stress corrosion cracking resistance, making it unsuitable as a material for terminals and connectors in the rapidly progressing electrical and electronic industries. May lack reliability. On the other hand, phosphor bronze has good strength, elasticity, corrosion resistance, and stress corrosion cracking resistance, but especially when strength is required, it is expensive because it contains 5% or more of Sn, and it also has poor conductivity and stress relaxation. It has the disadvantage of poor characteristics. JP-A-60-184655, JP-A-61-159541, JP-A-62-50428, etc. contain an appropriate amount of Ti.
A copper-based alloy containing Ni is shown. This type of alloy can be improved in strength and electrical conductivity by dispersing and precipitating a Ti--Ni compound in the matrix. The purpose of the present invention is to develop materials that have the characteristics that have become more stringently required for materials for terminals and connectors as a result of recent advances in electrical and electronic components. By containing an appropriate amount of Zn and properly regulating its manufacturing conditions, it has good strength, elasticity, and electrical conductivity, as well as good bending workability, heat-resistant solder plating adhesion, and
The present invention provides a high-strength copper alloy for terminals and connectors with excellent stress relaxation properties. [Summary of the Invention] The alloy of the present invention has Ni: 1.0 to 4.0 in weight%.
%, Ti; 0.5 to 2.0%, provided that the weight percentage ratio of Ni/Ti is in the range of 1.2 to 3.3, Zn: 0.1 to 3.0%, and in some cases, one of Zr, Mg, P, and B.
Species or two or more species individually or in total 0.01-0.5
%, with the remainder consisting of Cu and unavoidable impurities, and has a structure in which Ni-Ti based intermetallic compounds are uniformly and finely precipitated in a Cu matrix.By the following manufacturing method, it can be made into terminals, connectors, and lead frames. It is possible to create an alloy that has all the required properties. That is, according to the invention, in weight %
Ni: 1.0~4.0%, Ti: 0.5~2.0%, however, Ni/Ti
The weight percentage ratio ranges from 1.2 to 3.3, Zn: 0.1 to
Contains 3.0%, and in some cases further Zr, Mg, P,
One or more of B, singly or in total
A copper alloy sheet material containing 0.01~0.5% and the balance consisting of Cu and unavoidable impurities is produced, and this is heated to 900%.
Solution treatment is carried out at a temperature of ℃ or above, followed by cold rolling with at least one annealing at a temperature of 700 to 800℃ for 1 to 60 minutes during cold rolling to the final plate thickness.
Provided is a method for producing a high-strength copper alloy for terminals and connectors, which is characterized by performing aging treatment at a temperature of 400 to 600°C for 5 to 720 minutes. In particular, in the alloy of the present invention, the annealing performed during cold rolling has an advantageous effect on the properties after aging, as shown in the examples below,
A material having good electrical conductivity and moldability in a well-balanced manner can be obtained. [Detailed Description of the Invention] Below, the reasons for selecting the content range of the additive elements of the alloy of the present invention and the manufacturing conditions will be individually explained. The basic feature of the copper-based alloy of the present invention is that precipitation strengthening and dispersion strengthening are achieved by Ni-Ti intermetallic compounds, and for this purpose Ni and Ti are essential elements in the alloy of the present invention. If the Ti content is less than 0.5% (weight %, the same applies hereinafter), the effect of improving strength and elasticity will be small even in the coexistence with Ni. On the other hand, if the Ti content exceeds 2.0%, the amount of precipitates increases excessively, reducing the ductility, bending workability, and plating reliability of the alloy. Therefore, the Ti content of the alloy of the present invention is in the range of 0.5 to 2.0%. Ni is an element that forms a compound with Ti and contributes to improving strength and elasticity. It also has the effect of making the casting structure finer and preventing coarsening of crystal grains during solution treatment. To achieve this effect,
It is necessary to contain 1.0% or more, but if the content exceeds 4.0%, the electrical and thermal conductivity decreases significantly. Therefore, the Ni content should be in the range of 1.0 to 4.0%. Further, the object of the present invention is achieved when Ni and Ti are precipitated as a Ni-Ti intermetallic compound. this
It has been found that in order to fully exhibit the strengthening effect due to the precipitation of Ni-Ti intermetallic compounds, it is necessary to set the Ni/Ti weight percentage ratio in the range of 1.2 to 3.3. If the Ni/Ti ratio is less than 1.2,
A Ti-Cu intermetallic compound, which is a compound of Ti and Cu, precipitates with aging. Even if this Ti-Cu based intermetallic compound precipitates, there is little improvement in electrical and thermal conductivity. Furthermore, crystal grains tend to become coarse during solution treatment, and therefore surface roughness tends to occur during bending. For this reason, the Ni/Ti ratio needs to be 1.2 or more. On the other hand, if the Ni/Ti ratio is greater than 3.3, the amount of Ni remaining in the matrix increases, reducing electrical and thermal conductivity. For these reasons, it is necessary to keep the Ni/Ti ratio in the range of 1.2 to 3.3 in order to fully exhibit the characteristics of the alloy of the present invention. Zn improves the plating reliability of the alloy of the present invention. Specifically, it improves the heat-resistant adhesion of Sn plating and Sn-Pb plating. Sn plating or Sn-Pb plating is commonly used for plating electrical and electronic parts, but when this plating is applied to a material containing Ni or Ti, such as the alloy of the present invention, it may not last long due to current flow or environment. When heated for a long time, Ni and Ti may diffuse to the plating interface and react with the Sn of the plating to form a reaction diffusion layer. Since this reaction-diffusion layer is fragile, when it is formed, the plating is likely to peel off, reducing the plating reliability. Adding an appropriate amount of Zn suppresses the diffusion of Ni and Ti in Cu, effectively suppressing the formation of a reaction-diffusion layer at the interface. Therefore, in the alloy of the present invention, Zn functions beneficially to improve plating reliability. In addition, since Zn has a deoxidizing effect, it also acts as a deoxidizing agent for molten metal, and it also improves the flowability of molten metal, thereby improving castability. In order to exhibit the effect of Zn addition, it is necessary to contain 0.1% or more, but if the content exceeds 3.0%, the electrical conductivity decreases significantly, and the susceptibility to stress corrosion cracking increases and the corrosion resistance decreases. do. For these reasons, the Zn content is set in the range of 0.1 to 3.0%. Zr, Mg, P, and B are useful as deoxidizing agents during melting of the alloy of the present invention. Sufficient deoxidation also prevents the oxidation of Ni and Ti, which are additive elements, and can also improve the material properties of the alloy. For example, Zr and Mg have the effect of improving the strength and elasticity of the alloy of the present invention, and P and B have the effect of improving the workability. In order to obtain such an effect, one or more of these elements may be added in a total amount of 0.01% or more.
However, if the content exceeds 0.5% in total, electrical conductivity and bending workability will decrease. Therefore, the total amount of one or more of these elements added is in the range of 0.01 to 0.5%. The copper-based alloy of the present invention, which has been adjusted to such a composition, simultaneously has various properties that satisfy the demands of modern electrical and electronic components by uniformly and finely dispersing and precipitating Ni-Ti intermetallic compounds. The material can be made of Such properties can be advantageously developed by a manufacturing method that employs appropriate heat treatment conditions during processing. The details of the manufacturing method will be explained below. First, Ni: 1.0 to 4.0%, Ti: 0.5 to 2.0%, however, the weight percentage ratio of Ni/Ti is in the range of 1.2 to 3.3, Zn: 0.1 to 3.0%, and in some cases further,
A slab containing 0.01 to 0.5% of one or more of Zr, Mg, P, and B, singly or in total, with the remainder being Cu and unavoidable impurities, is produced by melting and casting. This melting and casting is preferably carried out in an inert gas or reducing gas atmosphere. Next, the slab (ingot) is hot-rolled to produce a hot-rolled plate, and descaling is performed. Below, this hot-rolled sheet is solution-treated at a temperature of 900℃ or higher, and during cold rolling to the final thickness,
At least 1 annealing for 1-60 minutes at a temperature of 800℃
The material is sandwiched and cold rolled, and then subjected to an aging treatment at a temperature of 400 to 600°C for 5 to 720 minutes, and the effects thereof will be explained in order. Solution treatment must be performed at 900°C or higher. At temperatures below 900° C., the steel will not be sufficiently solutionized and, therefore, the coarse precipitates generated during the hot rolling process will not disappear sufficiently, making it impossible to improve the properties. Furthermore, it is difficult to adjust the crystal grains at temperatures below 900°C. Regarding the timing of this solution treatment, in order to eliminate the waviness of the plate that may occur due to solution treatment and to impart appropriate work hardening,
It is best to carry out before cold rolling. Aging treatment is carried out in the final step of sheet manufacturing, and is carried out at a temperature of 400 to 600°C for 5 to 720 minutes. If the temperature exceeds 600°C, the precipitated Ni-Ti intermetallic compound will aggregate and become coarse, and no improvement in properties can be expected, and if the temperature is less than 400°C, the time required for precipitation will be too long, which is not preferable. Therefore, the aging temperature is 400
~600℃ range. Regarding the aging time, if it is less than 5 minutes, the formation of precipitates will be insufficient, and if it is for a long time, such as exceeding 720 minutes, it is not preferable from the viewpoint of the growth of precipitates and from the economic point of view. On the other hand, in cold rolling, when rolling to the target thickness, cold rolling is performed with at least one annealing for 1 to 60 minutes at a temperature of 700 to 800 degrees Celsius during rolling. It is possible to further improve the electrokinetic rate and bending workability. This intermediate annealing is performed at a temperature lower than the solution treatment temperature and higher than the aging treatment temperature. In other words, at temperatures lower than 700°C, aging precipitation progresses and the material hardens, reducing subsequent rollability and bending workability.
Perform at a temperature of 700℃ or higher. However, at temperatures exceeding 800°C, the alloy becomes significantly softened, and recrystallization begins, resulting in mixed crystal grains that reduce the bending workability of the material. Therefore, the annealing temperature is 700
~800℃ range. Regarding the annealing time, if it is less than 1 minute, the effect of improving the electrical conductivity and bending workability will be small, and if it exceeds 60 minutes, the alloy will become significantly softened and an appropriate hardness cannot be maintained, so the annealing time is set to 1 to 60 minutes. The effect of this intermediate annealing is two-stage aging treatment (the first stage is aging treatment performed at a lower temperature and the second stage is performed at a higher temperature).
Although there are some similarities with the first stage, it can be considered that there are fundamental differences in tissue behavior and action. This point will be explained in Examples below. By performing the above heat treatment, a thin plate of a copper-based alloy having a structure in which a Ni-Ti intermetallic compound is finely and uniformly dispersed and precipitated in a Cu matrix can be manufactured. This alloy, as shown in the examples below,
It has high strength, high elasticity, and high conductivity, and has excellent bending workability, plating reliability, stress relaxation properties, etc., so it can be used as a material for terminals and connectors that enables the miniaturization of electrical and electronic components in recent years. It is suitable. Example 1 Copper-based alloys No. 1 to No. 11 whose chemical composition values (wt%) are shown in Table 1 were melted using a high-frequency melting furnace.
It was cast into a 40mm x 40mm x 140mm ingot. The melting and casting atmosphere was completely shielded with inert gas. Each ingot was cut into a size of 40 mm x 40 mm x 10 mm, and this ingot was hot rolled at 950°C to obtain a hot rolled plate with a thickness of 3 mm. After face milling, it was cold rolled to 1mm and heated to 950°C.
Solution treatment was carried out for 30 minutes at a temperature of . After quenching with water and pickling, this material was cold rolled to a thickness of 0.4 mm without intermediate annealing, and subjected to aging treatment at a temperature of 500°C for 60 minutes.The material after this treatment was used as a test material. In each of the heat treatments described above, the atmosphere was an inert gas or reducing gas atmosphere to suppress oxidation on the surface and inside of the material as much as possible. Using the obtained test materials, hardness, tensile strength, spring limit value, electrical conductivity, bending workability, and solder adhesion were investigated, and the results are shown in the column without intermediate annealing in Table 2. In addition, when cold rolling the solution-treated materials of each copper-based alloy No. 1 to No. 11 with a thickness of 1 mm to a thickness of 0.4 mm,
First stage cold rolling to 0.6mm, then 750℃ x 30
An aged material was manufactured under the same conditions as in the previous example, except that intermediate annealing was performed for 20 minutes, followed by second cold rolling to 0.4 mm, and the results of the same tests are shown in Table 2. Indicated in the Yes column. Hardness, tensile strength, spring limit value, and electrical conductivity were measured in accordance with JISZ2244, JISZ2241, JISH3130, and JISH0505, respectively. The bendability is
90°W bending test (CES-M0002-6, R=0.4mm)
The test pieces were evaluated as ◯ if the center ridge surface was good, and as × if cracks occurred. Solder adhesion was determined by solder plating (dip: Sn-40wt.%Pb, 230℃
×5sec, using weakly activated rosin flux), then heated and held at 150℃ for 720 hours, bent tightly, and performed a peeling test with cellophane tape. It was evaluated as ×. The following is clear from the results in Table 2. Alloys No. 1 to No. 7 according to the present invention have an excellent balance of hardness, tensile strength, spring limit value, and electrical conductivity, and also have good bending workability and solder adhesion. Therefore, it can be seen that this alloy has extremely excellent properties as a high-strength copper alloy for terminals and connectors. On the other hand, comparative alloy No. 8, which has a larger Ni/Ti ratio than specified in the present invention, has low strength and elasticity.
Comparative alloy No. 9, in which the Ni/Ti ratio is smaller than that specified in the present invention, has low electrical conductivity. Therefore, even if the amounts of Ni and Ti are within the range specified in the present invention,
If the Ni/Ti ratio is outside the range specified by the present invention, the material properties will be unbalanced and the object of the present invention cannot be achieved. Furthermore, comparative alloy No. 10 to which Zn was not added had poor solder adhesion, and comparative alloy No. 11, in which the Ti content was higher than the amount defined by the present invention, had poor bending workability and poor solder adhesion. It is clear that when intermediate annealing is performed, the electrical conductivity is significantly improved compared to when no intermediate annealing is performed.

【table】

[Table] In addition, the stress relaxation properties of the present invention alloy No. 1 shown in Table 1 and commercially available phosphor bronze (C5191H material 0.4 mm ^t ) were specified, and the results are shown in Table 3. In the test, U-shaped bending was performed so that the stress at the center of the test piece was 45 kgf/mm ² , and the bending after holding at a temperature of 150° C. for 500 hours was calculated as the stress relaxation rate using the following formula. Stress relaxation rate (%) = {(L ₁ − L ₂ )/(L ₁ − L ₀ )}×
100 However, L ₀ : Jig length (mm) L ₁ : Sample length at start (mm) L ₂ : Horizontal distance between sample edges after processing (mm)

Table 3 shows that the alloy of the present invention has a lower stress relaxation rate and superior stress relaxation properties than phosphor bronze, which is a typical conventional material for terminals and connectors. Example 2 An alloy having the chemical composition No. 7 in Table 1 was manufactured under different manufacturing conditions. Each manufacturing condition is as follows. (1) Same as Example 1 without intermediate annealing. (2) Same as Example 1 with intermediate annealing. In other words, when cold rolling a solution-treated material with a thickness of 1 mm to a thickness of 0.4 mm, the first stage of cold rolling is performed to 0.6 mm, then intermediate annealing is performed, and then the second stage of cold rolling is performed to 0.4 mm. The procedure was the same as in Example 1 except for the following. At that time, intermediate annealing was performed at 750°C for 30 minutes. (3) Same as Example 1 without intermediate annealing except that the solution treatment was performed at 850°C for 30 minutes (comparative example where the solution treatment temperature is low). (4) Same as Example 1 without intermediate annealing except that the solution treatment was 900°C x 30 minutes and the aging treatment was 390°C x 60 minutes (comparative example with low aging treatment temperature). (5) Same as Example 1 without intermediate annealing except that the solution treatment was 900°C x 30 minutes and the aging treatment was 610°C x 30 minutes (comparative example with high aging treatment temperature). (6) The conditions for intermediate annealing were the same as in (2) above, except that the conditions were 820°C x 30 minutes. (7) The conditions for intermediate annealing were the same as in (2) above, except that the conditions were 680°C x 30 minutes. Each of the obtained materials was tested using the same measuring method as in Example 1, and the hardness, tensile strength, spring limit value, electrical conductivity, and bending workability were investigated, and the results are shown in Table 4.

[Table] As is clear from Table 4, alloy (2) produced according to the method of the present invention has an excellent balance of hardness, tensile strength, spring limit value, and electrical conductivity, and has good bending workability. On the other hand, Comparative Example (3) with a low solution treatment temperature, Comparative Example (4) with a low aging temperature, and Comparative Example (5) with a high aging temperature have a good balance of strength, elasticity, and electrical conductivity. It can be seen that the bending properties of (3) and (5) are even worse. Comparative Example (6), which had a high intermediate annealing temperature, was inferior in hardness, tensile strength, spring limit value, and bending workability. This is because the annealing temperature is too high.
It is thought that the precipitation nuclei of the Ni-Ti-based compound are not generated, or even if they are generated, they are re-dissolved, and recrystallization begins to occur, resulting in mixed grains, which adversely affects the strength and bending workability. On the other hand, Comparative Example (7) in which the intermediate annealing temperature was low had excellent strength but poor bending workability. This is because the annealing temperature is too low and enters a temperature range where Ni-Ti compounds precipitate and grow one after another on dislocation lines or grain boundaries, and as a result, the increase in internal strain due to aging precipitation becomes excessively large. Even though cold rolling and aging treatment can improve strength, electrical conductivity, etc., it is thought that moldability cannot be improved. Note that even when the final aging temperature is set to approximately the same temperature as in Comparative Example (7), the spring limit value and bending workability deteriorate as seen in Comparative Example (5). In this way, after solution treatment and during cold rolling before aging treatment, the alloy of the present invention was heated at 700 to 800°C x 1 to 60°C.
Performing an intermediate annealing for 30 minutes provides a beneficial effect in obtaining a terminal/connector material having a good balance of strength, elasticity, electrical conductivity, and formability. The reason why such an effect is produced is that
Since the solution treatment is performed at a temperature of 900℃ or higher, the added elements such as Ni and Ti are sufficiently re-dissolved, and the crystal grains are adjusted to be uniform.
Since rolling is applied to the supersaturated solid solution plate material before annealing, dislocations are introduced and there are many places where precipitates can nucleate.Furthermore, at this annealing temperature, the formation and formation of precipitate nuclei of Ni-Ti compounds. Precipitation・
Although growth occurs, the compound can be precipitated uniformly and finely by subsequent rolling processing and aging treatment, and therefore Ni and Ti dissolved in the matrix are reduced as much as possible. Conceivable. As described above, according to the method of the present invention, a high-strength copper alloy for terminals and connectors that has high strength, high elasticity, and high conductivity, and has excellent bending workability, plating reliability, and stress relaxation properties can be obtained. This makes it possible to provide a useful material that can fully respond to the recent trends in the miniaturization of electrical and electronic components and the increased density of circuits.

Claims (1)

[Claims] 1% by weight: Ni: 1.0-4.0%, Ti: 0.5
~2.0%, however, if the Ni/Ti weight percentage ratio is
Range of 1.2-3.3, Zn: 0.1-3.0%, the balance
A copper alloy plate material consisting of Cu and unavoidable impurities is produced, and it is solution-treated at a temperature of 900°C or higher, and then cold-rolled to the final thickness at 700-800°C.
Cold rolled with at least one annealing for 1-60 minutes at a temperature of 400-600℃, then 5-60 minutes of annealing at a temperature of 400-600℃.
A method for manufacturing high-strength copper alloys for terminals and connectors, which is characterized by performing an aging treatment for 720 minutes. 2 In weight%, Ni: 1.0-4.0%, Ti: 0.5
~2.0%, however, if the Ni/Ti weight percentage ratio is
Range of 1.2 to 3.3, including Zn: 0.1 to 3.0%, and further Zr,
Producing a copper alloy plate material containing one or more of Mg, P, and B in an amount of 0.01 to 0.5% individually or in total, with the balance being Cu and unavoidable impurities;
This is solution treated at a temperature of 900°C or higher, and then rolled at a temperature of 700 to 800°C during cold rolling to the final thickness.
A method for producing a high-strength copper alloy for terminals and connectors, which comprises cold rolling with at least one annealing period of ~60 minutes, followed by aging treatment at a temperature of 400~600°C for 5~720 minutes.