JPH0611904B2 - High-strength, high-conductivity copper alloy manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a high-strength, high-conductivity copper alloy, and more specifically, it is used as a material for electronic parts, particularly semiconductor lead frames and terminals. Tensile strength 33
kgf / mm ² or more, elongation 25% or more and conductivity 65% IA
The present invention relates to a method for producing a high strength, high conductivity copper alloy having CS.

[Prior Art] Conventionally, it is disclosed in Japanese Examined Patent Publication No. Sho 5 that a copper alloy containing 1.5 to 3.0 wt% of Fe is processed to produce a material such as an electronic component.
No. 2-020404, Japanese Patent Publication No. 55-014132, Japanese Patent Publication No. 55-014133 and Japanese Patent Publication No. 5
No. 5,014,134.

In the above-mentioned Japanese Examined Patent Publication No. 55-014134, Fe1.
A copper alloy containing 5 to 3.0 wt% and essentially Cu as the balance is hot-worked at a temperature of 800 ° C to 1020 ° C.
Cold working is performed at a rolling reduction of 0% or more, and aging annealing is performed at a temperature of 400 ° C. to 550 ° C. for 30 minutes or more.
A method of cooling at a cooling rate of 0 ° C./1 hour or less is shown. In this method, there is no explanation that the combination of cold rolling and aging annealing is one cycle, and it is said that three cycles are most desirable, and mechanical properties and electrical conductivity have some values.

That is, the conventional treatment process of a copper alloy containing essentially 1.5% to 3.0% by weight of Fe and the balance being Cu is basically 400 ° C.
It is indispensable to perform annealing at a temperature of up to 550 ° C. for 30 minutes or more and cold rolling with a reduction ratio of 30% or more for two cycles or more, ideally three cycles. Therefore, considering these steps, annealing is required. Since it is carried out in a bell-shaped furnace in a coiled state, it is necessary to perform a step of preventing adhesion during annealing before annealing and a step of removing oxide scale after annealing twice or three times.

[Problems to be Solved by the Invention] In the present invention, in view of the problem that the processing steps of the conventional method described above are complicated, as a result of intensive studies by the present inventor, as a result of the conventional method, three cycles were obtained. There is no need to perform the process, and the combination of cold rolling and aging annealing is performed in one cycle, resulting in a tensile strength equivalent to that of the conventional method (35.2 kgf / m
m ² ), elongation (27.5%) and conductivity (73.5% IACS)
We have developed a method for producing a high-strength, high-conductivity copper alloy suitable for electronic parts and the like.

[Means for Solving Problems] A feature of the method for producing a high-strength, high-conductivity copper alloy according to the present invention is that the copper-based alloy contains Fe 1.5 to 3.0 wt% and the balance is Cu. 800 ingots
Hot rolling at a temperature of ℃ to 1050 ℃, and then cold rolling at a total surface reduction rate of 90% or more, and at a temperature of 550 ℃ (excluding 550 ℃) to 600 ℃ for 30 minutes or more and 2 hours or less After annealing, the annealing is performed for 30 minutes to 6 hours at a temperature of 475 ° C to 525 ° C during cooling.

In the method for producing a high-strength, high-conductivity copper alloy according to the present invention, first, an ingot of a copper-based alloy containing 1.5 to 3.0 wt% of Fe is agglomerated by a continuous casting method or the like. Then, this copper-based alloy is hot-rolled at a temperature of 800 ° C to 1050 ° C. This is because the crystallized substance of Fe generated in the solidification process of the ingot is solid-dissolved in copper, which increases the amount of fine crystallized substance of Fe in the subsequent annealing, which improves the strength by aging. Greater effect. Therefore, such effects cannot be expected at temperatures below 800 ° C, and 1050 ° C
This effect becomes saturated when the value exceeds.

After this hot rolling, the cold rolling was performed to obtain a total area reduction rate of 9
It is performed at 0% or more. This area reduction rate will be described.

That is, 400 ℃ or more and 500 ℃ or more during melting and cooling after casting.
When the cooling rate is slow in the temperature range below, Fe tends to precipitate, and a part of Fe precipitates. These Fe are 4
At a temperature of 75 to 525 ° C., among the precipitates generated when it takes 30 minutes or more, large precipitates that are not compatible with the mother phase do not contribute to the strength improvement. Therefore, it is necessary to perform quenching from the constant temperature solid solution region of Fe after hot rolling. The hot rolling is a means for heating the solid solution of Fe crystallized in the ingot into the parent phase and thinning the plate with low energy. At the temperature after the hot rolling, precipitation of Fe occurs. To finish rolling at a temperature of 650 ° C or higher, which is a difficult temperature, and perform quenching at a temperature of 650 ° C or higher, the plate thickness after hot rolling is 20 mm.
Below, it is desirable to set it to 15 to 18 mm.

Furthermore, in order to adjust the hot-rolled sheet material with a thickness of 10 to 20 mm by performing only one aging treatment, 90
Area reduction rate of over%.

In addition, by increasing the area reduction rate of the plate material before aging, and in the case of a material with a large amount of work strain, the nuclei generated during the precipitation of Fe become uniform and the internal energy increases, so a uniform and large amount of precipitate
e The size of the precipitate becomes fine. Therefore, it is preferable that the area reduction rate (cold rolling rate) is high, and the total area reduction rate is 90%.
That is all.

Thus, the hot rolling is followed by the cold rolling, and then the copper-based alloy is annealed. As in the past, when cold rolling and aging annealing are repeated, by aging annealing,
The Fe precipitates once precipitated are aggregated and coarsened by the subsequent aging annealing, but the coarsened Fe precipitates do not contribute to the strength improvement of the copper alloy.

In the method for producing a high-strength, high-conductivity copper alloy according to the present invention, the strength of the copper alloy is improved because cold rolling and aging annealing are performed in one cycle without repeating.

Further, the annealing after the cold rolling is a two-stage annealing, that is, first, the cold rolled copper base alloy is
It is heated to a temperature of more than 0 ° C to 600 ° C and annealed for 30 minutes or more and 2 hours or less, and immediately thereafter, 475 ° C to 525 ° C.
It is cooled to the temperature of and is annealed at that temperature for 30 minutes or more and 6 hours or less.

The first annealing is for finely recrystallizing the structure of the rolled copper-based alloy, and at the annealing temperature of less than 550 ° C., the recrystallization of the structure does not proceed and the strength is not improved. Further, since the solid solution of Fe progresses at a temperature exceeding 600 ° C and the electrical conductivity deteriorates, the annealing temperature is 550 ° C.
It is necessary to exceed ~ 600 ° C. Further, in order for the structure to be sufficiently recrystallized, an annealing time of 30 minutes or more is required, and recrystallization is performed to adjust the size of the crystal, and if it exceeds 2 hours, such an effect is not remarkable.

The second annealing is an aging annealing performed to precipitate Fe, which improves the conductivity. And, in order to precipitate Fe efficiently, 475 ° C. to 52 ° C.
It is necessary to anneal at a temperature of 5 ° C. for 30 minutes or more and 6 hours or less. If the second annealing is less than 30 minutes, Fe cannot be efficiently precipitated, and the effect becomes more prominent as the annealing is performed for a longer time, but if it exceeds 6 hours, the effect becomes less prominent.

As described above, after the first annealing, the second annealing is continuously performed during the cooling, whereby the grain size of the recrystallized grains in the copper alloy and the precipitation strengthening by Fe precipitates are performed. A copper alloy excellent in strength and conductivity can be obtained. Moreover, since the first annealing and the second annealing are not interrupted, it is possible to save energy without increasing the number of steps.

Thus, the high-strength, high-conductivity copper alloy manufacturing method according to the present invention is performed in one cycle without repeating cold rolling and aging annealing, and by adopting two-stage annealing,
A Cu-1.5 to 3.0Fe alloy having the same characteristics as the conventional one can be easily manufactured at low cost.

In order to further improve the properties, cold rolling is performed, and in order to remove the local strain caused by the cold rolling, the temperature is 300 ° C to 400 ° C (not including 400 ° C) for 5 seconds or more. May be annealed.

In the method for producing a high-strength, high-conductivity copper alloy according to the present invention, the annealing at a temperature of 550 to 600 ° C. is performed once, and the adhesion prevention measure before the annealing and the oxide scale removal after the annealing are each 1 The process can be shortened because it can be done only once.

Further, in the method for producing a high-strength, high-conductivity copper alloy according to the present invention, the copper alloy used is P0.02 to 0.1 wt%, Zn0.0
Even if one or two selected from the range of 1 to 0.5 wt% is contained, the target characteristics, especially the electrical conductivity, can be satisfied.

In addition, Mn, Sn, Al, Ni, Ti and Cr are 0.
Even if the content of 002 to 0.2 WT% is contained, the electrical conductivity of 65% satisfies IACS, so that it is acceptable.

[Example] An example of a method for producing a high-strength, high-conductivity copper alloy according to the present invention will be described.

Example Cu-2.3 wt% Fe-0.15w under charcoal coating in a small electric furnace
Melt t% Zn-0.03wt% P and cast into a tilting cast iron book mold, thickness 60mm, width 60mm, length 18
A 0 mm ingot was produced.

The front surface and the back surface of each of these ingots were chamfered by 2.5 mm, hot rolling was started at a temperature of 900 ° C. to a thickness of 10 mm, and the steel was put into water from a temperature of 700 ° C. and rapidly cooled. The oxide scale on the surface of this hot rolled material was removed by a glider.

The hot rolled material is cold rolled with a thickness of 10 mm to
Although it was processed to 0.635 mm, there was no cracking in the ears.

First, after degreasing this intermediate rolled material with trichlene,
530 ° C, 575 ° C and 6 in an inert gas atmosphere furnace
The temperature was kept at 50 ° C. for 2 hours each. Subsequently, 25 ° C at a temperature of 425 to 550 ° C during cooling
Annealing was performed for 2 hours at intervals.

The characteristics of thus obtained are shown in Table 1.

The annealing was performed in a nitrogen gas furnace after degreasing trichlene, and after the annealing, the oxide scale was removed with an aqueous solution containing 184 g / 1 of sulfuric acid.

The tensile strength was set parallel to the rolling direction, and the shape of the test piece was ASTM E8.

As a comparison method, the above hot-rolled material having a thickness of 10 mm was cold-rolled to a thickness of 2.54 mm, and this material was subjected to 2 at a temperature of 490 ° C.
Annealed for an hour, pickled, then cold rolled to a thickness of 1.27mm
Then, this material is annealed at a temperature of 440 ° C. for 2 hours, further pickled, and then cold rolled to a thickness of 0.635 m.
This material was annealed at a temperature of 440 ° C. for 2 hours, and the result of No. 19 in Table 1 was obtained.

The following are clear from Table 1.

The copper-based alloys No. 9 to No. 11 produced by the method for producing a high-strength, high-conductivity copper alloy according to the present invention have tensile strengths that do not have to be annealed three times as shown in Comparative Example No. 19. 33 kgf / mm ²
As described above, it has an elongation of 25% or more and an electrical conductivity of 65% IACS or more, and shows the characteristics equivalent to those of Comparative Example No. 7.

No. 20 is as follows: first annealing temperature 575 ° C, annealing time 25 minutes, second annealing temperature 500 ° C, annealing time 1
For 20 minutes and No. 2, the first annealing temperature is 575 ° C., the annealing time is 180 minutes, the second annealing temperature is 500 ° C., and the annealing time is 120 minutes.

Further, when the first annealing temperature in the two-step annealing step is less than 550 ° C, the tensile strength is not sufficient, and at the temperature exceeding 600 ° C, the electrical conductivity does not satisfy 65% IACS. And
If the second annealing temperature is less than 475 ° C. or exceeds 525 ° C., the conductivity does not satisfy 65% IACS.

[Effects of the Invention] As described above, the high-strength, high-conductivity copper alloy manufacturing method according to the present invention has the above-described structure, and thus contains conventionally used Fe1.5 to 3.0 wt%. It is a simplified process of hot-rolling a copper-based alloy consisting of the balance Cu, and nevertheless has exactly the same properties as conventional process materials. The effect of saving time, including saving time including setup of the annealing furnace, reducing the number of picklings, suppressing the decrease in yield that occurs each time rolling, annealing, and pickling are repeated, and reducing costs. Therefore, it greatly contributes industrially from resource saving and energy saving.

Claims (1)

[Claims] 1. A copper-based alloy ingot containing 1.5 to 3.0 wt% of Fe and the balance of Cu is 800
Hot rolling at a temperature of ℃ to 1050 ℃, and then cold rolling at a total surface reduction rate of 90% or more, and at a temperature of 550 ℃ (excluding 550 ℃) to 600 ℃ for 30 minutes or more and 2 hours or less The method for producing a high-strength, high-conductivity copper alloy, which comprises performing annealing for 30 minutes or more and 6 hours or less at a temperature of 475 ° C. to 525 ° C. during the cooling after annealing.