JP3410125B2 - Manufacturing method of high strength copper base alloy - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength copper-base alloy suitable as a material for electric and electronic parts typified by lead frames and the like. . 2. Description of the Related Art In recent years, with the development of the electronics industry, the use of electric and electronic parts materials such as lead frames has increased, and high reliability has been required in terms of characteristics.
In terms of cost, even lower prices are required. Here, the lead frame is a "single frame structure that supports the IC leads during and after the manufacturing process", and the required characteristics include (1) thermal and electrical conductivity. Is good. One of the main functions of the lead frame is to dissipate the heat generated in the chip in order to prevent the deterioration of the Si chip. It is required that the electric conductivity is good in order to reduce the heat generation of the metal. Here, since a proportional relationship is generally recognized between the thermal conductivity and the electrical conductivity, the evaluation is typically represented by measuring the magnitude of the electrical conductivity. (2) High strength. Since the lead frame supports the leads of the IC during and after the manufacturing process, sufficient strength is required for this. The evaluation criteria include that the tensile strength and proof stress are large, and that the stiffness (lumbar strength) and the spring limit value are sufficient. (3) To have sufficient heat resistance. It is expected that the lead frame will be heated to some extent during or after the manufacturing process. Therefore, sufficient heat resistance is required so that the strength does not deteriorate due to such a thermal load. However, in practice, if the heat-resistant temperature is too high, it is expected that there will be disadvantages in terms of cost, such as an increase in the annealing temperature during material production. Therefore, practically 450
It is sufficient if the resin is not softened by heating at a temperature of about several minutes. (4) Good bending workability. In most lead frames, the lead portion is bent, so that good bending workability is required. Examples of the evaluation include a VW bending test and a repeated bending test. (5) Good plating adhesion and solder weather resistance. In a lead frame, an inner lead is often plated with Ag or Au, and an outer lead is often plated with solder. Therefore, good plating adhesion and solder weather resistance are required. The lead frame is required to have the above-mentioned various characteristics. However, heretofore, an inexpensive material having the above-mentioned various properties at the same time cannot be obtained. SUMMARY OF THE INVENTION The present invention relates to a copper-based alloy having the above-mentioned various characteristics required for a material for electric / electronic parts such as a lead frame, and more particularly to a strength, heat and An object of the present invention is to provide a method for producing a copper-based alloy having excellent electric conductivity and excellent heat resistance and bending workability. [0010] The present invention provides a Cu—Ni—
In an Al-based alloy, by performing aging treatment twice after solution heat treatment under the condition of composition that balances strength and electrical conductivity at the highest level, high strength, elasticity, spring limit value and excellent formability can be obtained. A method for producing a high-strength copper-based alloy is provided. That is, the present invention provides Ni: 6 to 10.8 w
%, Al: 1 to 2 wt%, the composition ratio of Ni / Al is in the range of 4 to 7 by weight, and Zn: 0.01
B: 0.005 to 0.1 wt%, including one or two of 0.005 to 2.0 wt% in total, oxygen: 0.005 wt% or less, the balance being Cu and In rolling a copper-based alloy material comprising unavoidable impurities, the material is first hot-rolled at a temperature of 700 ° C. or more and a working ratio of 80% or more, and at least in a cooling process after the hot rolling.
Cooling rate of 50 ° C / min or more in the temperature range of 700 to 300 ° C
And then the primary cold pressure at a cold working rate of 70% or more
Cast, then the plate after rolling cold at a temperature of eight hundred and twenty to nine hundred and twenty ° C. performed 60 to 600 seconds solution heat treatment, then 40
Intermediate heat treatment at a temperature of 0 to 600 ° C for 5 to 360 minutes
After processing, the reduction rate is 70% or more, and the reduction rate is 70-95%.
Next cold rolling, as final treatment at 380-700 ℃
The present invention relates to a method for producing a high-strength copper-based alloy, which comprises performing a tension annealing treatment for 360 seconds. Next, the reason why the composition range of the copper-based alloy according to the present invention is limited as described above will be described. (1) Ni: Ni forms a solid solution in a Cu matrix to improve strength, elasticity, and heat resistance, and further forms a compound with Al to disperse and precipitate, thereby improving electric conductivity.
Moreover, strength and elasticity are improved. However, if the Ni content is less than 6% by weight, the above-mentioned effects cannot be sufficiently obtained, while if it exceeds 12% by weight, the electrical conductivity is significantly reduced even in the presence of Al, and is economically disadvantageous. Becomes
Therefore, the Ni content is in the range of 6 to 12% by weight. (2) Al: Al is less than 1% by weight of Ni
The effect of improving strength, elasticity and heat resistance is insufficient even in the coexistence with, while if it exceeds 2% by weight, the precipitates become excessively large, and the ductility, formability and plating property of the alloy are reduced. Since the castability is reduced and it is economically disadvantageous, the Al content is in the range of 1 to 2% by weight. (3) Ni: Al component composition ratio Ni, Al is precipitated as a Ni-Al intermetallic compound, and the above-mentioned basic characteristics of the present invention are advantageously achieved. The composition ratio (weight ratio) of the Ni / Al component is in the range of 3 to 10 in order to more fully exhibit the property enhancement by the Ni-Al intermetallic compound. The reason is that when the composition ratio (weight ratio) of the Ni / Al component is less than 3, the amount of precipitates becomes excessively large, and the ductility, formability and plating property of the alloy are reduced, and the castability is also reduced. On the other hand, when the Ni / Al component composition ratio (weight ratio) is larger than 10, Ni
Is excessively dissolved in the Cu matrix,
Electric conductivity is not reduced, and strength and elasticity cannot be efficiently improved. (4) Zn Zn has an effect of improving the heat-resistant adhesion of a surface treatment layer such as Sn plating or molten solder, and not only improves the reliability of plating and surface treatment of the present alloy, but also has strength and elasticity. It has the effect of further improving heat resistance. Such an effect is due to Zn
If the content is less than 0.01% by weight, it is not sufficient, while 2.
If the content exceeds 0% by weight, the electric conductivity and the moldability are significantly reduced, and the castability is also decreased, which is disadvantageous economically. Therefore, the Zn content is in the range of 0.01 to 2.0% by weight. (5) BB B contributes as a deoxidizing agent during melting and casting of the alloy of the present invention.
Further, it has an effect of preventing the crystal grains from becoming coarse during the solution treatment. If the B content is less than 0.005% by weight, such an effect is not sufficient, and if the B content exceeds 0.1% by weight, the moldability deteriorates and it is economically disadvantageous. 0.005 to 0.1% by weight. (6) Oxygen Oxygen content is 0.005% by weight (50 ppm)
If a larger amount is contained in the alloy, Al having a high affinity for oxygen is oxidized to Al ₂ O ₃ , which leads to deterioration in characteristics such as plating property, plating reliability, and reduction in press die life. . When the oxygen content is high, when H ₂ gas is used in the production process of the alloy, there is a concern that hydrogen embrittlement occurs on the surface and inside. Therefore, the oxygen content is in the range of 0.005% by weight or less. The copper-based alloy according to the present invention, which has been adjusted to the above-described component composition, is capable of precipitating Ni-Al based intermetallic compounds finely to obtain various characteristics required for recent lead frame materials. It can be a combined material. The copper-based alloy produced by the method of the present invention has a component composition containing 6 to 12% by weight of Ni and 1 to 2% by weight of Al in Cu as described above. Ni-A by controlling heat treatment conditions after cold rolling in a manufacturing process of processing a slab of a copper base alloy having a component composition to a desired thickness by hot rolling and cold rolling.
A major feature is that the l-type intermetallic compound is finely precipitated to achieve precipitation hardening effectively. In the hot rolling step, the ingot is for example 85
The treatment is carried out by heating to 0 ° C. or higher and the hot rolling finish temperature to 700 ° C. or higher. When the hot rolling reduction at that time is set to 80% or more, the cast structure can be completely crushed, and the influence of segregation in the ingot can be eliminated. In the cooling process after the hot rolling, the temperature range from 700 ° C. or more to 300 ° C. or less, that is, at least 700 to 300 ° C.
Cool at a cooling rate of 0 ° C./min or more. This cooling is preferably performed by a rapid water cooling method, and the purpose of the rapid cooling is to obtain a hot-rolled material in which Ni and Al are dissolved. Cooling rate in the above temperature range is 5
If the temperature is lower than 0 ° C./min, these elements are precipitated during the cooling process to produce a coarse Ni—Al compound. If the quenching start temperature is lower than 700 ° C. even in the case of quenching at 50 ° C./min or higher, and if the cooling rate is lower than 50 ° C./min even if the quenching start temperature is 700 ° C. or higher, the coarse cooling rate may be large. Ni-Al-based compounds precipitate. It is not expected that the Ni-Al compound precipitated at this stage will improve the strength, elasticity, heat resistance and stress relaxation resistance. The cooling end point temperature of the quenching temperature is 30.
The temperature must be 0 ° C. or lower. The reason is that at a temperature of 300 ° C. or lower, precipitation of the Ni—Al-based compound does not substantially occur. As described above, in the present invention, the Ni—Al compound is not precipitated in the hot rolling process,
It is first important to obtain a hot-rolled material in which Al is dissolved. The hot-rolled material obtained as described above is
After being subjected to surface grinding or pickling as required, it is subjected to cold rolling. The cold rolling step is a step of obtaining a sheet material having a predetermined thickness by repeating cold rolling and heat treatment. In the method of the present invention, the first solution heat treatment, the intermediate heat treatment and the tension annealing treatment are performed. By appropriately controlling the processing conditions, a product in which fine Ni-Al-based compounds are precipitated can be manufactured, and in this process, coarsening due to aggregation of the Ni-Al-based compounds is prevented as much as possible. The above-mentioned ingot is rolled by hot rolling (a working ratio of 80% or more), and then subjected to primary cold rolling. At this time, if the cold working ratio is less than 70%, the time required to eliminate segregation during casting in the subsequent solution heat treatment step becomes significantly long, so that the cold working ratio of the first cold rolling is 70% or more. Is preferred. Next, 820 to 920 are applied to the plate material.
A solution heat treatment is performed at a temperature of 60C for 60 to 600 seconds. If the temperature of the solution heat treatment is less than 820 ° C., Ni and Al do not sufficiently dissolve in the matrix, while if it exceeds 920 ° C., the crystal grains become coarse in a short time, so the temperature of the solution heat treatment is 820 to 920 ° C. And the processing time is 60
If the time is less than 2 seconds, segregation during casting remains and the solution heat treatment is insufficient. On the other hand, if the time exceeds 600 seconds, the crystal grains become coarse and uneconomical.
The range is 00 seconds. Next, as an intermediate heat treatment (aging treatment),
Heat treatment is performed at a temperature of 400 to 600 ° C. for 5 to 360 minutes. However, if the temperature is lower than 400 ° C., the time required for precipitation is too long, which is uneconomical. Saturates. Therefore, the aging treatment temperature is in a temperature range of 400 to 600 ° C. If the aging time is less than 5 minutes, the formation of precipitates is insufficient, while if it exceeds 360 minutes, the formation of precipitates is saturated,
The aging treatment time is in the range of 5 to 360 minutes because it is uneconomical. Next, the material after the first cold rolling → solution heat treatment → intermediate heat treatment (aging treatment) is subjected to a second cold rolling (working ratio: 70% or more). Is preferably 70 to 95%. If it is less than 70%, the working strain imparted by the working is small, and the improvement in strength and elasticity in aging precipitation in the next heat treatment step (tension annealing treatment) becomes insufficient. Significantly, the mechanical properties become directional (anisotropic), and the moldability decreases. Therefore, the working ratio of the secondary cold rolling is preferably 70 to 95%. Next, as final processing, 380-700 ° C.
At a temperature of 5 to 360 seconds. When the heat treatment temperature is lower than 380 ° C., the time required for aging precipitation becomes too long, which is uneconomic. On the other hand, when the heat treatment temperature is higher than 700 ° C., overaging occurs, and further improvement in properties cannot be expected. Therefore, the tension annealing temperature is set in a temperature range of 380 to 700 ° C. If the treatment time is less than 5 seconds, the formation of precipitates is insufficient, and if the treatment time is longer than 360 seconds in one direction, it is not preferable from the viewpoint of growth of the precipitates and from the viewpoint of economy.
Therefore, the tension annealing time is set in the range of 5 to 360 seconds. That is, the summary is as follows. a) In a cooling process after hot rolling, a temperature range from a temperature of 700 ° C. or more to a temperature of 300 ° C. or less is cooled at a cooling rate of 50 ° C./min or more. b) The first primary cold rolling is performed at a rolling reduction of 70% or more. c) Then at a temperature of 820-920 ° C. for 60-600 seconds,
A solution heat treatment is performed. d) Next, an intermediate heat treatment is performed at 400 to 600 ° C. for 5 to 360 minutes. e) The cold working ratio of the secondary cold rolling is set to 70% or more. f) As a final treatment, a tension annealing treatment is performed at 380 to 700 ° C. for 5 to 360 seconds. By performing working and heat treatment under the above conditions a) to f), a thin plate of a copper-based alloy having a structure in which a Ni-Al-based intermetallic compound is finely precipitated in a matrix can be produced. As shown in (1), it is excellent in high strength, high elasticity, and high conductivity, so that it is most suitable as a material for electric and electronic parts such as recent lead frames. Next, the present invention will be described specifically with reference to examples. EXAMPLES Copper-based alloy Nos. Having the chemical component values (% by weight) shown in Table 1 were obtained. 1 to No. 13 was smelted using a high-frequency induction melting furnace and continuously cast into an ingot of 20 × 100 × 1000 (mm). However, the atmosphere during melting and casting was an Ar gas seal. The material of the mold was a carbon mold, and the drawing was performed at an average drawing speed of 100 mm / min by a pulse method. After rolling the obtained ingot to a thickness of 4 mm (t) by hot rolling (working ratio: 80%),
Rapid cooling from 0 ° C. (the cooling rate from 700 ° C. to 300 ° C. at this time was a rate exceeding 50 ° C./min.), And rolling to a thickness of 1 mm (t) by cold rolling (working rate: 75).
%), And processing was performed until each final step in the A method according to the method of the present invention and the B method, which is a conventional method, as a comparative example. Method A (method of the present invention) A cold-rolled sample having a thickness of 1 mm (t) is heat-treated at a temperature of 850 ° C for 300 seconds, and then rapidly cooled with water. Then
This heat-treated material is subjected to an intermediate heat treatment at a temperature of 500 ° C. for 30 minutes, then cold-rolled (working rate: 75%) to a thickness: 0.25 mm (t), and tensioned at a temperature of 500 ° C. for 180 seconds. An annealing process is performed. Method B (Comparative Method) A cold-rolled sample having a thickness of 1 mm (t) is heat-treated at a temperature of 630 ° C. for 360 minutes. Next, the heat-treated material is cold-rolled (working rate: 60%) to a thickness of 0.4 mm (t), heat-treated at a temperature of 880 ° C. for 300 seconds, and then water-quenched. Thereafter, cold rolling (working rate: 38%) is performed to a thickness of 0.25 mm (t), and a tension annealing treatment is performed at a temperature of 420 ° C. for 180 seconds. (That is, after the solution heat treatment, no intermediate heat treatment is performed, and the final working ratio is also different.) Method A Continuous casting → hot rolling → cold rolling → solution heat treatment → intermediate heat treatment 1 mm (t) → cold Rolling → tension annealing 0.25 mm (t) B method Continuous casting → hot rolling → cold rolling → heat treatment → cold rolling 1 mm (t) 0.4 mm (t) → solution heat treatment → cold rolling → Tension annealing treatment 0.25 mm (t) The heat treatment in each step of the above-mentioned A method and B method made the atmosphere an inert or reducing gas atmosphere and suppressed the oxidation of the material surface and the inside as much as possible. A above
Hardness using the test material prototyped by the
Investigating strength, spring limit, conductivity and bending workability,
Table 1 shows the results. The measurement of hardness, tensile strength, spring limit value, and electrical conductivity was conducted according to JIS-Z-2244, JIS-Z-
2241, JIS-H-3130 and JIS-H-0
505. The bending workability was measured by a 90 ° w bending test (CES).
-M-0002-6, R = 0.2 mm, bending axis parallel to the rolling direction), and a good mountain surface at the center
Marks and those with cracks were evaluated as x marks. [Table 1] In Table 1, the alloy No. of the present invention is shown. Nos. 1 to 4 were treated by the A method to improve the characteristics, and were subjected to solution heat treatment → intermediate heat treatment (aging treatment) → tension annealing treatment (aging treatment), that is, two aging treatments after the solution heat treatment. It is. Comparative alloy no. 5 to 11 are A
It is an alloy processed by the method, but has a different component composition range from the copper-based alloy according to the present invention. Comparative alloy No. 5 to 8 each have a Ni content of 6% by weight.
(Out of the specified range), the tensile strength is 80 kgf.
/ Mm ² could not be obtained, and the comparative alloy No. 9 ~
In No. 10, the workability is poor because the Al content exceeds the upper limit of the specified range of 2% by weight. Comparative alloy No. In No. 11, the Ni content exceeds the upper limit of the specified range of 12% by weight.
Although the spring limit value has been improved, the workability is remarkably poor, causing breakage. Comparative alloy no. 12, No. No. 13 is treated by the B method, that is, subjected to one aging treatment after the solution heat treatment (the final reduction ratio is also different). Both alloys have significantly lower hardness, tensile strength, and spring limit value than the alloys of the invention A (Nos. 1 to 4).
In particular, for example, No. 13 and N
o. As compared with No. 10, the characteristic value is no. 13 shows a significantly lower value. No. 13 has a conductivity of No. 13; No. 10 is significantly lower than that of No. 10 in the matrix. It is presumed that this is because the solid solution was dissolved in a larger amount than 10. As is clear from the results in Table 1, Cu-N
When the i-Al alloy is treated by the method A of the present invention, various properties are remarkably superior to those treated by the method B of the comparative method. In particular, Cu- (6 to 12% by weight) Ni
-(1-2% by weight) An Al-based copper-based alloy having a proper Ni / Al component composition ratio (weight ratio) of 3 to 10 is treated by the method of the present invention (method A), whereby the alloy No. of the present invention is obtained. . 1
As shown in Nos. 4 to 4, it is possible to produce a copper-based alloy material having an excellent balance between hardness, tensile strength, spring limit value, and electrical conductivity, and having excellent bending workability. As described above, according to the present invention, high strength,
It has high elasticity, high electrical conductivity, high thermal conductivity, and also has excellent workability, solder weather resistance and heat resistance, so it can be applied to various applications, especially as a material for electrical and electronic parts such as lead frames. A suitable high-strength copper-based alloy can be manufactured stably at low cost.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-149946 (JP, A) JP-A-63-250434 (JP, A) JP-A-63-266033 (JP, A) 50184 (JP, B2) JP 4-25340 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C22F 1/08 C22C 9/00-9/10

Claims (1)

(57) [Claims 1] Ni: 6 to 10.8 wt%, Al: 1 to 1
2 wt%, the composition ratio of Ni / Al is in the range of 4 to 7 by weight, and Zn: 0.01 to 2.0 wt%.
B: One or two of 0.005 to 0.1 wt% are contained in a total of 0.005 to 2.0 wt%, and oxygen is 0.0
When rolling a copper-based alloy material having a content of not more than 05 wt% and the balance being Cu and unavoidable impurities,
00 ° C. or higher, working rate: hot rolling at 80% or more, then the
At least 700-300 ° C in the cooling process after hot rolling
Cool the temperature range at a cooling rate of 50 ° C / min or more, and then
The first cold rolling is performed at a cold working rate of 70% or more, and then the cold-rolled sheet is heated at a temperature of 820 to 920 ° C. for 60 to 600 ° C.
Solution heat treatment for 2 seconds, then at a temperature of 400-600 ° C
After performing the intermediate heat treatment for 5 to 360 minutes at a processing rate of 70
% Or more, a secondary cold-rolling at a draft of 70 to 95%, and a tension annealing treatment at 380 to 700 ° C. for 5 to 360 seconds as a final treatment.