JPH0953162A - Production of soft copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce soft copper foil excellent in characteristics such as tensile strength and elongation, at the time of producing copper foil by subjecting tough pitch copper or the like to hot rolling and plural cold rolling including process annealing, by executing the final finish cold rolling under specified conditions. SOLUTION: An ingot of tough pitch copper, oxygen free copper or the like is subjected to hot rolling and rough rolling to be formed into a sheet material having about 1 to 2mm thickness, which is thereafter repeatedly subjected to plural cold rolling and process annealing to gradually reduce the thickness into a thin copper sheet of 0.1 to 0.5mm. Next, it is subjected to final process annealing by batch annealing in an atmosphere of an inert gas such as nitrogen to regulate the average grain size of the recrystallized grains of the copper sheet to >=50μm, which is thereafter subjected to cold rolling in such a manner that the cold working degree calculated by [ (final process annealing thickness)-(thickness before finish annealing)}/final process annealing thickness]×100 is regulated to >=60% to produce copper foil having <=10μm thickness. Next, this copper foil is subjected to finish annealing at 170 to 250 deg.C in an atmosphere of gaseous nitrogen to produce copper foil having excellent characteristics of 150 to 170N/mm<2> tensile strength and 6.0 to 8.5 elongation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a soft copper foil used as a shield material for electric wires and the like.

[0002]

2. Description of the Related Art In the conventional method for manufacturing a soft copper foil, first,
A tough pitch copper or oxygen-free copper raw material is melted and cast to obtain an ingot with a thickness of 50 to 300 mm, which is then hot-rolled and rough-rolled into a copper plate with a thickness of about 1.0 mm, followed by cold rolling. The soft copper foil with a thickness of 10 μm or less is obtained by repeating the intermediate annealing several times and gradually thinning it, but tough pitch copper and oxygen-free copper can increase the workability by cold rolling. Therefore, the cold workability after the final intermediate annealing is 90%.
After being rolled to the above temperature, the recrystallization completion temperature (the temperature at which the recrystallization is completed when the plate is in a heating and holding time of 30 minutes) is over,
Generally, soft copper foil is annealed at a temperature 10 to 50 ° C higher than the recrystallization completion temperature.

[0003]

In the step of coating an electric wire with a soft copper foil, a soft copper foil or a soft copper foil laminated with a synthetic resin film is generally adhered to the electric wire to cover the electric wire. Although a high tension is applied to the conventional soft copper foil, the conventional soft copper foil has a problem that the copper foil is broken or cracked during the process.

In order to solve the above problems, the present inventor has
When the tensile strength of the conventional soft copper foil was measured, the thickness was 9μ.
Tensile strength of 110 to 140 N / mm obtained by a tensile test using a soft copper foil with a width of 10 mm and a length of 150 mm as a test piece at a tensile speed of 10 mm / min and an initial chuck length of 50 mm.
^{2. The} growth was low at 3.0-4.5%. Therefore,
As a result of repeated research and experiments aimed at realizing a copper foil having both high tensile strength and elongation of a soft copper foil, if the development of a cubic orientation, which is a recrystallization texture after finish annealing, can be suppressed, soft copper foil The above technical problems have been achieved by obtaining conspicuous knowledge that a soft copper foil having sufficient tensile strength and elongation to be imparted to the foil and having durability against a high tensile load can be obtained.

[0005]

The above technical problems can be solved by the present invention as follows. That is, the method for producing a soft copper foil according to the present invention is, after hot rolling the ingot of tough pitch copper or oxygen-free copper, repeating cold rolling and intermediate annealing a plurality of times,
In the finish rolling after the final intermediate annealing, the cold workability calculated from [{(final intermediate annealing thickness)-(thickness before finishing annealing)} / final intermediate annealing thickness] x 100 is 60% or more. age,
Then, in the method of producing a soft copper foil having a thickness of 10 μm or less by performing finish annealing, the average crystal grain size of the recrystallized grains of the copper plate after the final intermediate annealing is 50 μm or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a soft copper foil according to the present invention will be described in detail below. Copper ingot melts
Conventional tough pitch copper or oxygen free copper having a thickness of about 30 to 300 mm obtained by casting can be used. This copper ingot is hot-rolled and rough-rolled to form a copper plate having a thickness of about 1.0 to 2.0 mm, which is gradually thinned by repeating cold rolling and intermediate annealing a plurality of times to form a copper plate having a thickness of about 0.1 to 0.5 mm. To do.

The intermediate annealing excluding the final intermediate annealing may be performed by a conventionally known method, but in order to make the average crystal grain size of the recrystallized grains of the copper sheet after the final intermediate annealing 50 μm or more, the final intermediate annealing is performed. It is more preferable that the annealing is carried out by a continuous annealing method or a batch type annealing, and the material temperature is 350 ° C. or higher, especially 400 ° C. or higher. Further, in the case of the continuous annealing method, since the heating and holding time is short, it is preferable that the material temperature is high. In the case of the batch type annealing, the coil surface temperature is usually held for 2 to 3 hours after reaching the target temperature. By extending the heating and holding time to 10 hours or longer, it is possible to obtain recrystallized grains having an average crystal grain size of 50 μm or more even at a material temperature of 350 ° C. When the average crystal grain size of the recrystallized grains is 50 μm or less, the cubic orientation, which is a recrystallized texture, develops after the finish annealing, and the tensile strength / elongation becomes small, which is not preferable. The upper limit of the average crystal grain size of the recrystallized grains is not particularly limited, but if it is too large, cutting or the like is likely to occur during rolling, so the average crystal grain size of the recrystallized grains is 50 to 150 μm. It is preferably in the range.

In cold rolling (finish rolling) before finish annealing,
It is preferable to repeatedly perform rolling within a range of 5 to 50% per one pass (passing a copper plate once between a pair of rolling rolls) to obtain one having a desired thickness. 60% cold workability before finish annealing
In the following, the copper foils may stick to each other after the finish annealing, and the next step may not be performed smoothly. The finish annealing may be a batch type annealing generally adopted, and the annealing may be performed at a temperature of 170 to 250 ° C.

The intermediate annealing is carried out by adopting a continuous annealing method or a batch type annealing, and the finish annealing is generally carried out by adopting a batch type annealing. In either method, however, in an inert gas atmosphere. The inert gas used is argon, nitrogen, etc., but if nitrogen gas is used,
It is economical. Further, the final intermediate annealing thickness for calculating the cold working degree is the plate thickness during intermediate annealing performed before starting the finish rolling, and the thickness before finish annealing is
It is the thickness of the copper foil obtained by the final cold rolling, that is, the product thickness. Further, the average crystal grain size of the recrystallized grains is simple according to the comparison method of the JIS H 0501 copper alloy grain size test method after electrolytic polishing the sample after the intermediate annealing and revealing the structure by chemical etching. You can ask.

In the present invention, in the final intermediate annealing, by performing an intermediate annealing step in which the average crystal grain size of the recrystallized grains of the copper plate or copper foil is 50 μm or more, [[(final intermediate annealing thickness)- (Thickness before finish annealing)} / Final intermediate annealing thickness] × 100% cold-rolled copper foil with a cold workability of 60% or more
When finish annealing is performed, the cubic orientation, which is a recrystallized texture, is less developed, and as a result, sufficient tensile strength and elongation can be obtained for the copper foil, resulting in high tension during the process of coating the copper foil on electric wires. On the other hand, a durable soft copper foil can be obtained.

[0011]

Hereinafter, examples of the present invention will be described together with comparative examples. Embodiment 1 FIG. Melted and cast, thickness 30 mm x width 200 mm x length
A tough pitch copper ingot of 300 mm was hot-rolled and rough-rolled into a 1.2 mm-thick copper plate, which was repeatedly annealed and cold-rolled to gradually reduce the thickness to 0.4 mm. A final intermediate annealing was carried out under the temperature of 400 ° C for 2 hours. When the average grain size after the final intermediate annealing was measured by the copper grain product grain size test method
It was 55 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 97.8% and a copper foil having a thickness of 9 μm.
Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and the elongation of this soft copper foil were measured, the tensile strength was 158 N / mm ² and the elongation was 6.8%.

Embodiment 2 FIG. Thickness obtained in the same manner as in Example 1
0.4mm copper plate was subjected to final annealing in batch annealing in a nitrogen atmosphere at a material temperature of 500 ° C for 2 hours.
The average crystal grain size was measured and found to be 80 μm. Subsequently, this copper sheet was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 97.8% and a copper foil having a thickness of 9 μm. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 171
It was N / mm ² and the elongation was 8.2%.

Embodiment 3. Thickness obtained in the same manner as in Example 1
A 0.2 mm copper plate was subjected to a final annealing in a batch annealing in a nitrogen atmosphere at a material temperature of 450 ° C for 2 hours.
The average crystal grain size was measured and found to be 70 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 95.5%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to a batch annealing in a nitrogen atmosphere under a nitrogen atmosphere for finish annealing at a material temperature of 200 ° C. for 2 hours to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 165 N
/ Mm ² , and the elongation was 6.7%.

Example 4. Thickness obtained in the same manner as in Example 1
A 0.1 mm copper plate was subjected to a final intermediate annealing at a material temperature of 350 ° C for 15 hours in a nitrogen atmosphere during batch annealing.
The average crystal grain size was measured and found to be 55 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 149
The N / mm ² and the elongation were 6.2%.

Embodiment 5 FIG. Thickness obtained in the same manner as in Example 1
0.1mm copper plate is subjected to final annealing in batch annealing under nitrogen atmosphere at a material temperature of 400 ° C for 2 hours.
The average crystal grain size was measured and found to be 70 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 153
It was N / mm ² and the elongation was 6.5%.

Embodiment 6 FIG. Thickness obtained in the same manner as in Example 1
0.1mm copper plate was subjected to final annealing in batch annealing under nitrogen atmosphere at a material temperature of 500 ° C for 2 hours.
The average crystal grain size was measured and found to be 95 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a batch atmosphere in a nitrogen atmosphere to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 168
It was N / mm ² and the elongation was 7.5%.

Embodiment 7 FIG. Thickness obtained in the same manner as in Example 1
A 0.1 mm copper plate was batch-annealed in a nitrogen atmosphere in an atmosphere of nitrogen at an object temperature of 250 ° C. for 2 hours, and then cold-rolled to 0.025 mm. Furthermore, in batch annealing, the final intermediate annealing was carried out under a nitrogen atmosphere at a material temperature of 400 ° C for 2 hours, and the average grain size was measured.
It was 80 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 64.0% and a copper foil having a thickness of 9 μm.
Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 170 N / mm ² and the elongation was 8.4%.

Embodiment 8 FIG. Melted and cast, thickness 30 mm x width
An oxygen-free copper ingot with a length of 200 mm and a length of 300 mm was hot-rolled and rough-rolled to form a copper plate with a thickness of 1.2 mm, which was repeatedly annealed and cold-rolled to gradually reduce the thickness to 0.4 mm, and then continuously. In the annealing method, the final intermediate annealing was carried out under a nitrogen atmosphere at a material temperature of 600 ° C. for 2 hours. The average crystal grain size after the final intermediate annealing was 60 μm as measured by the above-mentioned grain size test method for copper alloy products. Then, 1 for this copper plate
Repeated cold rolling was performed within the range of 5 to 50% per pass to obtain a total cold workability of 97.8% and a copper foil having a thickness of 9 μm. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 160 N / mm ² , the elongation was 6.3%.
Met.

Embodiment 9 FIG. Thickness obtained in the same manner as in Example 8
0.1mm copper plate is subjected to final annealing in batch annealing under nitrogen atmosphere at a material temperature of 400 ° C for 2 hours.
The average crystal grain size was measured and found to be 65 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 160
It was N / mm ² and the elongation was 7.2%.

Comparative Example 1 Thickness obtained in the same manner as in Example 1
0.4mm copper plate was subjected to final annealing in batch annealing in nitrogen atmosphere at a material temperature of 300 ° C for 2 hours.
The average crystal grain size was measured and found to be 30 μm. Subsequently, this copper sheet was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 97.8% and a copper foil having a thickness of 9 μm. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a batch atmosphere in a nitrogen atmosphere to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 140
The N / mm ² and the elongation were 4.2%.

Comparative Example 2 Thickness obtained in the same manner as in Example 1
A 0.2 mm copper plate was subjected to final annealing in batch annealing in a nitrogen atmosphere at a material temperature of 350 ° C for 2 hours.
The average crystal grain size was measured and found to be 40 μm. Subsequently, this copper foil was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 95.5%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 124
It was N / mm ² and the elongation was 3.2%.

Comparative Example 3. Thickness obtained in the same manner as in Example 1
A 0.1 mm copper plate was subjected to final annealing in a batch atmosphere under a nitrogen atmosphere at a material temperature of 300 ° C for 2 hours,
The average crystal grain size was measured and found to be 35 μm. Subsequently, this copper foil was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 133%.
The N / mm ² and the elongation were 4.5%.

Comparative Example 4. Thickness obtained in the same manner as in Example 1
A 0.1 mm copper plate was subjected to final intermediate annealing in a batch atmosphere under a nitrogen atmosphere at a material temperature of 350 ° C for 2 hours.
The average crystal grain size was measured and found to be 40 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 130%.
The N / mm ² and the elongation were 4.5%.

Comparative Example 5. Thickness obtained in the same manner as in Example 1
A 0.1 mm copper plate was batch-annealed in a nitrogen atmosphere under a nitrogen atmosphere at an intermediate temperature of 250 ° C. for 2 hours to perform intermediate annealing, and then cold rolled to 0.020 mm. Furthermore, in the batch type annealing, the final intermediate annealing was carried out in a nitrogen atmosphere at a material temperature of 250 ° C for 2 hours, and the average grain size was measured.
It was 40 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 55.0% and a copper foil having a thickness of 9 μm was obtained.
Finally, the copper foil was subjected to finish annealing in batch annealing in a nitrogen atmosphere at a material temperature of 200 ° C. for 2 hours. When the tensile strength and the elongation of this soft copper foil were measured, the tensile strength was 113 N / mm ² and the elongation was 0.7%, indicating that the soft copper foil was not fully softened.

Comparative Example 6. Thickness obtained in the same manner as in Example 8
A 0.4 mm copper plate was continuously annealed in a nitrogen atmosphere,
A final intermediate annealing was performed at a material temperature of 300 ° C. The average crystal grain size after the final intermediate annealing was measured by the above-mentioned grain size test method for copper alloy products and found to be 20 μm. Subsequently, this copper sheet was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 97.8% and a thickness of 9 μm.
I got a copper foil. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 141 N / mm ² , and the elongation was 4.
It was 2%.

Comparative Example 7. Thickness obtained in the same manner as in Example 8
A 0.1 mm copper plate was subjected to final annealing in a batch atmosphere under a nitrogen atmosphere at a material temperature of 300 ° C for 2 hours,
The average crystal grain size was measured and found to be 30 μm. Subsequently, this copper plate was repeatedly cold-rolled within a range of 5 to 50% per pass to obtain a total cold workability of 91.0%, and a copper foil having a thickness of 9 μm was obtained. Finally, this copper foil was subjected to finish annealing at a material temperature of 200 ° C. for 2 hours in a nitrogen atmosphere in batch annealing to obtain a soft copper foil. When the tensile strength and elongation of this soft copper foil were measured, the tensile strength was 135
The N / mm ² and the elongation were 3.8%.

The cubic orientation strengths of the soft copper foils in Examples 1 to 9 and Comparative Examples 1 to 7 were measured by X-ray diffraction (10).
The diffraction intensity of 0) was measured, the intensity ratio was calculated with the intensity of Comparative Example 2 being 1, and the results are shown in Table 1.

[0028]

[Table 1]

In the case of copper, it is generally known that the occupancy of the (100) cubic orientation increases sharply when the cold workability is 90% or more. Those having an average crystal grain size of 50 μm or more by annealing showed little development of (100) cubic orientation, which is a recrystallized texture after finish rolling and finish annealing, and as a result, high tensile strength and elongation were obtained.

[0030]

As described above, according to the present invention, the average crystal grain size of the recrystallized grains of the copper foil in the final intermediate annealing can be determined.
Since it is set to 50 μm or more, the development of cubic orientation, which is the recrystallized texture after finish annealing, is suppressed, and the tensile strength is 150 to 17
It is possible to obtain a high numerical value of 0 N / mm ² and an elongation of 6.0 to 8.5%, to give a copper foil sufficient tensile strength and elongation, and to obtain a soft copper foil that is durable against high tension and elongation. You can As a result, the copper tape is not broken or the copper foil portion is not cracked when it is covered with an electric wire or the like, and can be suitably used. Therefore, it can be said that the industrial applicability of the present invention is very high.

Claims (1)

[Claims] 1. After hot rolling an ingot of tough pitch copper or oxygen-free copper, cold rolling and intermediate annealing are repeated a plurality of times, and in final rolling after final intermediate annealing, [{(final intermediate annealing thickness) -(Thickness before finish annealing)} / final intermediate annealing thickness] ×
In the method of producing a soft copper foil having a thickness of 10 μm or less by subjecting the cold workability calculated from 100 to 60% or more, and then performing finish annealing, the average crystal of recrystallized grains of the copper plate after the final intermediate annealing. A method for producing a soft copper foil, which has a particle size of 50 μm or more.