JPH0418016B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a copper-based alloy for terminals and connectors that has excellent spring properties, strength, electrical conductivity, and workability, and a method for producing the same. [Prior art] Terminal/connector materials that make up the conductive terminals on the plug side and socket side have various properties such as elasticity, strength, stress relaxation properties, and corrosion resistance, regardless of their shape or size. Moreover, it is required to be a material that is easy to process and inexpensive. Brass and phosphor bronze are the most commonly used materials for such terminals and connectors. A conductive material (lead frame material) containing appropriate amounts of Ni, Fe, P, Sn and B in Cu is disclosed in Japanese Patent Publication No. 59-39492 filed by the same applicant. [Problems to be solved by the invention] Brass has the advantages of very good moldability and low cost, but its corrosion resistance and stress corrosion cracking resistance are extremely poor, so rapid progress has been made. It can be unreliable as a terminal/connector material in modern electrical or electronic industries. Although phosphor bronze has good strength, elasticity, corrosion resistance, and stress corrosion cracking resistance, it is expensive because it contains 3.0% or more of Sn, and it also has poor stress relaxation properties. Although the material described in Japanese Patent Publication No. 59-39492 is excellent as a lead frame material, it has a low spring limit value and is therefore not suitable for terminals and connectors. Also, the strength is not sufficient for terminals and connectors. [Means for solving the problems] The present invention provides a terminal and a device that solves the above-mentioned problems.
As a material for connectors, in weight%,
Sn; 1.0~2.0%, Ni; 0.05~0.40%, Fe; 0.16~
0.40%, P; 0.05-0.10%, B; 0.005-0.06%,
The remainder consists of Cu and unavoidable impurities, and Fe-Ni-
The present invention provides a copper-based alloy having a structure in which a P-based compound is dispersed and precipitated. The copper-based alloy according to the present invention exhibits spring properties and increases strength by adding an appropriate amount of Sn, and exhibits various properties favorable for terminals and connectors by precipitation hardening with Fe-Ni-P-based compounds. There is a basic characteristic in this point. As a method for manufacturing the alloy of the present invention to advantageously exhibit various properties preferable for terminals and connectors, Sn: 1.0 to 2.0%, Ni: 0.05 to 0.40%,
Fe; 0.16-0.40%, P; 0.05-0.10%, B; 0.005
~0.06%, the balance being Cu and unavoidable impurities. The process of manufacturing copper-based alloy slabs, where the slabs are rolled at a reduction rate of 60% or more and hot-rolled at a finishing temperature of 700.
After hot rolling at a temperature of 300°C or higher, substantially all of the alloying elements are solidified in the copper by cooling from the hot rolling finish temperature to a temperature of 300°C or lower at a cooling rate of 30°C/min or higher. The process of obtaining a melted hot-rolled sheet, the obtained hot-rolled sheet is subjected to the first cold rolling at a reduction ratio of 50% or more, and after this first cold rolling, the temperature is 400 to 600℃. Annealing for 5 to 720 minutes at a temperature of Provides a method for producing a copper-based alloy for terminals and connectors, which includes the following steps: a step of reducing the plate thickness by a process of reducing the plate thickness by a method of reducing the thickness of the copper-based alloy, and a step of performing tension annealing at a temperature of 300 to 750°C for 5 to 180 seconds after final cold rolling. It is something to do. The reason for determining the range of the content (wt%) of the additive elements in the copper-based alloy of the present invention will now be briefly explained. Sn forms a solid solution in the copper matrix to improve strength and spring limit. This effect is due to the Sn content.
Less than 1.0% is not sufficient; on the other hand, Sn content
If it exceeds 2.0%, conductivity and hot workability will deteriorate, and it will also be economically disadvantageous. For this reason, the Sn content of the copper-based alloy of the present invention is in the range of 1.0 to 2.0%. Ni is a solid solution in the copper matrix to improve strength, softening resistance, and corrosion resistance, but it is also an element that contributes to the formation of Fe-Ni-P compounds, which are the characteristics of the alloy of the present invention. It is necessary to add at least 0.05% or more. But 0.40
If the content exceeds %, the conductivity will decrease significantly and it will also be economically disadvantageous. Therefore,
Ni content shall be 0.05 to 0.40%. When Fe is dissolved as a supersaturated solid solution in the copper matrix, it forms a compound with Ni and P by aging and precipitates in the copper matrix, improving strength, spring limit value, and softening resistance. If the Fe content is less than 0.16%, the strength, spring limit value and softening resistance will be low;
If it exceeds 0.40%, conductivity and moldability will decrease. Therefore, the Fe content should be in the range of 0.16 to 0.40%. P functions as a deoxidizing agent during melting of the alloy of the present invention, and also provides an anti-oxidation effect for Sn and Fe, thus playing an important role in obtaining a sound ingot. P, which is supersaturated as a solid solution in the copper matrix, forms a Fe--Ni--P based compound together with Fe and Ni. If the P content is less than 0.05%, this effect will not be sufficient, and if it exceeds 0.10%, the conductivity and processability will deteriorate. Therefore, the P content should be in the range of 0.05 to 0.10%. B contributes to improving the elongation of the alloy of the present invention. This is considered to be because B, together with P, enhances the deoxidizing effect of the molten metal of the alloy of the present invention and reduces solute oxygen atoms in the copper matrix, thereby reducing interaction with dislocations during processing. If B is less than 0.005%, the deoxidizing effect will not be sufficient and the elongation improving effect will not be fully exhibited. Increasing the B content improves the deoxidizing effect, but the solid solubility limit of B in the copper matrix is around 0.06% at room temperature, and when this solid solubility limit is exceeded, compounds of Cu and B are formed. On the contrary, workability deteriorates. For this reason, the B content is set in the range of 0.005 to 0.06%. The copper-based alloy according to the present invention having such a composition is mainly solid solution strengthened by Sn and Fe-Ni-P.
Due to the synergistic effect of precipitation hardening of the system compound,
It can have both the strength and spring limit value required for terminals and connectors, and also have sufficient electrical conductivity.
These properties can be advantageously brought out by appropriately controlling the manufacturing conditions when processing a slab to a desired thickness through a hot rolling process and a cold rolling process. The details of the manufacturing method will be explained below. Hot rolling process A slab having the composition according to the present invention is produced by melting and casting, and this slab (ingot) is subjected to hot rolling. Heating and hot rolling reduction rate of 60% or more, preferably 90
% or more, and the hot rolling finishing temperature is preferably 700°C or more. As a result, the cast structure can be completely crushed, and the influence of segregation occurring in the ingot can be eliminated. Then, it is cooled at a cooling rate of 30°C/min or more in a temperature range from the hot rolling finishing temperature to 300°C or less. This cooling is preferably carried out by performing rapid water cooling immediately after hot rolling. This means Fe, Ni
A hot rolled material in which P is completely dissolved in solid solution can be obtained. If this cooling after hot rolling is performed at a cooling rate slower than 30° C./min, these elements will precipitate during the cooling process to form coarse Fe--Ni--P compounds. Even if this temperature range is rapidly cooled as described above, if the rapid cooling start temperature is lower than 700℃,
Furthermore, even if the quenching start temperature is 700°C or higher, if the cooling rate is slower than 30°C/min, coarse Fe-
A Ni-P compound precipitates. The Fe-Ni-P-based compound precipitated at this stage is incompatible with the parent phase,
This cannot be expected to improve the spring limit value or stress relaxation properties. Therefore, in the present invention
One of the characteristics of this method is that hot rolling conditions are adopted such that a hot rolled sheet in which Fe, Ni, and P are completely dissolved in solid solution is obtained. Note that the cooling end point temperature during this rapid cooling may be 300°C or less. This is because precipitation of Fe-Ni-P compounds does not substantially occur at temperatures below 300°C. Cold rolling and annealing process The hot-rolled plate obtained in the previous process is then subjected to surface grinding or pickling as necessary, and then cold-rolled to the desired plate thickness by performing cold rolling with annealing a necessary number of times. However, the initial cold rolling and annealing conditions are made appropriate to uniformly precipitate fine Fe-Ni-P compounds at this stage. First, the first cold rolling has a reduction rate of 50% or more.
It is preferably carried out at 80% or more, and annealing after this first cold rolling is carried out at a temperature of 400 to 600° C. for 5 to 720 minutes. This initial cold rolling and annealing conditions are extremely important in the present invention. If the reduction ratio in the first cold rolling is less than 50%, the rolling structure will not become homogeneous, and in the subsequent annealing, Fe-Ni-
P-based compounds cannot be precipitated uniformly and finely. If this first annealing is carried out at a temperature above 600°C,
The precipitated Fe-Ni-P compounds aggregate and coarsen,
Further improvement in spring limit value and formability cannot be expected, and Fe−Ni−
Since the time required to precipitate the P-based compound is too long, the first annealing may be performed at a temperature of 400 to 600°C and the annealing time may be in the range of 5 to 720 minutes.
If the annealing time is less than 5 minutes, the formation of the Fe-Ni-P-based compound will not be sufficient, and recovery of elongation due to this annealing will be insufficient. However, if the time is longer than 720 minutes, the growth of fine precipitates will progress, which is undesirable and becomes an economical burden. By appropriately performing the first cold rolling and annealing in this way, a material with Fe-Ni-P-based compounds precipitated finely and uniformly is obtained. Inter-rolling may be performed as many times as necessary. If cold rolling is performed several times during this process, intermediate annealing may be performed. After cold rolling to a desired thickness, the cold rolled material is subjected to tension annealing at a temperature of 300 to 750°C for 5 to 180 seconds. Through this tension annealing, it is possible to improve the spring limit value and recover the elongation, and it is possible to obtain a product that is homogeneous and has good flatness. When carrying out this tension annealing treatment, it is important to note that temperatures below 300°C have little effect in relieving local residual stress, while temperatures above 750°C soften the material even for a short period of time. The temperature is preferably 300 to 750°C. Further, regarding the treatment time, it is preferable to set the treatment time to a range of 5 to 180 seconds, since a homogeneous material cannot be obtained if the treatment time is less than 5 seconds, and no difference in effectiveness will be seen even if the treatment time exceeds 180 seconds. Examples of the present invention are listed below. Example No. 1 whose chemical component values (weight %) are shown in Table 1
~10 copper-based alloys were melted using a high-frequency vacuum melting furnace and cast into ingots of 40 mm x 40 mm x 140 mm. This ingot was cut into a size of 40 mm x 40 mm x 20 mm, and the ingot was soaked at 850°C, hot rolled to a thickness of 5 mm, and cooled in water from a temperature of 750°C.
The obtained hot-rolled sheet was cold-rolled to a thickness of 1.0 mm by the first cold rolling, and then annealed at 550°C for 60 minutes. Then, cold rolling was performed at a reduction rate of 50% to obtain a cold rolled plate with a thickness of 0.5 mm. 10kg of the obtained cold-rolled plate
Tension annealing was performed at 400° C. for 20 seconds while applying a tension of f/mm ² . The material that had undergone this treatment was used as a test material. Note that No. 11 in the table does not undergo the above manufacturing process, but is commercially available phosphor bronze annealed at a low temperature. The tensile strength, elongation, electrical conductivity, spring limit value, and softening temperature of each test material were measured, and the material was also subjected to a 90°W bending test. These measurement results are also listed in Table 1. Measurement of tensile strength and elongation is according to JIS-Z-2241.
The conductivity was measured in accordance with JIS-H-0505, and the spring limit value was measured in accordance with JIS-H-3130. The softening temperature is the temperature at which the hardness after heating becomes 80% of the initial hardness when the sample is heated at that temperature for 30 minutes. The 90°W bending test was conducted in accordance with the regulations of CES-M0002-6. In other words, 90°W with R = 0.2mm jig
Investigate the condition of the central mountain surface when bending,
Those with cracks were rated as x, those with slight wrinkles were rated as △, and those that were good were rated as ○. In addition, in FIG. 1, the relationship between Sn content, tensile strength, elongation, electrical conductivity, and spring limit value is summarized and shown for alloys No. 1 to No. 8 in Table 1. In addition, the present invention alloy No. 5 and comparative alloy No. 11 in Table 1
The stress relaxation properties were measured and the results are shown in Table 2. In the test, U-shaped bending was performed so that the stress in the center of the specimen was 80% of the proof stress.
The bending after holding at a temperature of 1,000 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 : Length of the jig (mm) L ₁ : Length of the sample at the start (mm) L ₂ : Horizontal distance between the edges of the sample after processing (mm).

【table】

【table】

[Table] The following is clear from the results in Table 1. All alloys No. 1 to No. 5 according to the present invention have a tensile strength of 50 Kgf/mm ² or more, a spring limit value of 45 Kgf/mm ² or more, and an electrical conductivity of 33% or more, and have excellent bending workability and a softening temperature. is also over 440℃. Therefore, it can be seen that this is an extremely excellent copper-based alloy for terminals and connectors. On the other hand, comparative alloys No. 6 and No. 7, which contain less Sn than specified in the present invention, and comparative alloy No. 9, which contains less Sn and Fe, both have a low strength spring limit value. In addition, comparative alloy No. 10, which has a higher Fe content than specified in the present invention, has poor bending workability.
No. containing more Sn than specified in the present invention.
Although comparative alloy No. 8 has lower conductivity, there is no problem in terms of characteristics as a terminal/connector. However, it has the disadvantage of poor hot workability. The results in Table 2 show that the alloy of the present invention has superior stress relaxation properties compared to phosphor bronze, which is a typical conventional terminal/connector material. Moreover, as seen in FIG. 1, it can be seen that as the amount of Sn increases in the alloy of the present invention, the strength, spring limit value, and hardness improve.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between strength, spring limit value, hardness, electrical conductivity, elongation, and Sn content in the alloy of the present invention.

Claims (1)

[Claims] 1% by weight: Sn: 1.0-2.0%, Ni: 0.05
~0.40%, Fe; 0.16~0.40%, P; 0.05~0.10%,
B: A copper-based alloy for terminals and connectors, consisting of 0.005 to 0.06%, the balance being Cu and unavoidable impurities, and having a structure in which a Fe-Ni-P compound is dispersed and precipitated in a copper matrix containing Sn and B as a solid solution. 2 In weight%, Sn: 1.0-2.0%, Ni: 0.05
~0.40%, Fe; 0.16~0.40%, P; 0.05~0.10%,
B: Process of manufacturing a slab of copper-based alloy consisting of 0.005 to 0.06%, the balance being Cu and unavoidable impurities, hot rolling the slab at a rolling reduction of 60% or more and a finishing temperature of 700.
After hot rolling at a temperature of 300°C or higher, substantially all of the alloying elements are solidified in the copper by cooling from the hot rolling finish temperature to a temperature of 300°C or lower at a cooling rate of 30°C/min or higher. A step of obtaining a melted hot-rolled sheet, the hot-rolled sheet is cold-rolled for the first time under a reduction ratio of 50% or more, and after this first cold-rolling, the hot-rolled sheet is heated at a temperature of 400 to 600°C. By annealing for 5 to 720 minutes at
- A step of finely dispersing and precipitating a Ni-P compound, a step of reducing the thickness of this annealed material by cold rolling to a desired thickness, and a temperature of 300 to 750°C after the final cold rolling. 5~180
A method for manufacturing copper-based alloys for terminals and connectors, which involves a process of tensile annealing for seconds.