JP2907415B2 - Manufacturing method of ultra-thin soft copper foil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultra-thin soft copper foil which can be suitably used as a shielding material for electric wires and the like.

[0002]

2. Description of the Related Art Conventionally, a copper foil having a thickness of 10 μm or less has been used as a shielding material for covering an electric wire.
In the step of covering the electric wire with the copper foil, a high tension is applied to the copper foil because the copper foil is closely adhered to the electric wire to cover the electric wire. However, since the thickness of the copper foil is as thin as 10 μm or less, the tensile strength and elongation of the copper foil are low, and the copper foil may be cut. Also, when laminating a copper foil having a thickness of 10 μm or less and a synthetic resin film, high tension is applied to the copper foil and cracks may occur.

It is obvious to those skilled in the art that as the thickness of the copper foil becomes thinner, the elongation of the copper foil becomes lower and its tensile strength becomes lower. Therefore, in the case of covering an electric wire, a person skilled in the art generally makes an attempt to prevent high tension from being applied to the copper foil. For example, an attempt has been made to laminate a synthetic resin sheet or the like on a copper foil so that high tension is not applied to the copper foil itself.

[0004] By the way, conventionally used copper foils are:
It is manufactured by the following method.
That is, a 50-300 mm thick tough pitch copper or oxygen-free copper ingot is subjected to hot rolling, and then cold rolling and intermediate annealing are repeated to form a foil having a thickness of 10 μm or less, and then the foil is softened. For this reason, finish annealing is performed at a temperature equal to or higher than the recrystallization temperature to obtain a copper foil. And, since tough pitch copper and oxygen-free copper can increase the workability by cold rolling, after the final intermediate annealing, the cold workability is reduced.
Cold rolling is performed to an extent exceeding 95%, and then finish annealing is performed.

[0005]

Under the above technical situation, the present inventor has conducted various studies in order to obtain a copper foil which maintains a high tensile strength even when the thickness becomes 10 μm or less. . As a result, when the ultra-thin copper foil is obtained by a specific method without using the above-described conventional method, even if the thickness becomes 10 μm or less, a relatively high elongation and a relatively high They have found that they retain high tensile strength. That is, tough pitch copper or oxygen-free copper is generally set to a very high degree of cold working (to about 95% or more) in the cold working. It has been found that, when the thickness is set to be low, relatively high elongation and relatively high tensile strength are maintained even when the thickness becomes 10 μm or less.

[0006]

That is, the present invention provides an ingot of tough pitch copper or oxygen-free copper which is subjected to hot rolling, cold rolling, intermediate annealing, and finish annealing to obtain an ultrathin film having a thickness of 10 μm or less. In the method for producing a soft copper foil, the degree of cold working by cold rolling performed between the final intermediate annealing and the finish annealing is 95% or less, and the finish annealing temperature (T ° C) is recrystallized. The present invention relates to a method for producing an ultrathin soft copper foil, wherein the temperature ≤ T 属 C ≤ (recrystallization temperature + 80 属 C).

In the present invention, an ingot of tough pitch copper or oxygen-free copper is first prepared. Tough pitch copper, oxygen Cu
About 0.02 to 0.05 wt% in the form of ₂ O is that of pure copper containing. Oxygen-free copper is pure copper having an extremely low oxygen content.

The ingot of tough pitch copper or oxygen-free copper is
Hot rolling is performed under conventionally known conditions, and then cold rolling and intermediate annealing are performed several times. Then, a final intermediate annealing is performed to obtain a copper plate having a thickness of about 0.02 to 0.2 mm. After the final intermediate anneal, the copper plate is subjected to a cold rolling step before the finish anneal. A feature of the present invention resides in that the degree of cold working in this cold rolling step is set to 95% or less. If the degree of cold work exceeds 95%, the elongation of the resulting ultra-thin copper foil decreases, and the tensile strength also decreases, which is not preferable. The degree of cold working (%) here is defined by the following equation. That is, assuming that the thickness of the copper plate after the final intermediate annealing is t ₀ and the thickness of the copper foil after the cold rolling step is t ₁ , [(t ₀ −t ₁ ) / t ₀ ] × 100. Is defined by

After the final intermediate annealing, the degree of cold working is 95%
Through the cold rolling process set below, the thickness
A copper foil of 10 μm or less is obtained. Then, the copper foil is subjected to finish annealing. The temperature condition of finish annealing (T ° C.) is as follows: recrystallization temperature ≦
Performed at T ° C ≦ (recrystallization temperature + 80 ° C). Even if the finish annealing is performed at a temperature lower than the recrystallization temperature, the obtained copper foil is not sufficiently softened and the elongation is not increased. Also, when the finish annealing is performed at a temperature exceeding (recrystallization temperature + 80 ° C), the elongation does not increase and the tensile strength decreases,
Not preferred. The recrystallization temperature referred to in the present invention means a heating temperature at which recrystallization is completed when the heating time is 30 minutes. The specific temperature of the recrystallization temperature varies depending on the material and the degree of cold work, but is generally 130 to 2
Since the temperature is about 20 ° C., the specific conditions of the finish annealing are as follows. That is, when the copper foil is flat-annealed in the state of a flat plate, the temperature is generally about 1 hour at a temperature of 160 to 180 ° C.,
If the copper foil is to be annealed in the state of a coil, 170-200
Generally about 5 hours at ℃.

[0010] Before or after the finish annealing, the copper foil may be subjected to a degreasing treatment. The degreasing treatment is performed to remove the rolling oil because the rolling oil is applied to the surface of the copper foil when the copper foil is cold-rolled. Generally, it is preferable to perform a degreasing treatment before the finish annealing.

The copper foil obtained by the above method has high elongation and high tensile strength. Specifically, it is higher than the elongation (3.0-4.5%) of the copper foil obtained by the prior art, and the tensile strength (12-14 kgf / mm ² ) of the copper foil obtained by the prior art
Is more expensive. Therefore, when used as a shield material when coating an electric wire, it is easy to coat the electric wire and is hard to be cut even when a high tension is applied. In the above description, the case of using as a shielding material for covering electric wires has been mainly described, but the ultra-thin soft copper foil obtained by the method according to the present invention is used for bonding with a synthetic resin film or the like. Can be suitably used.

[0012]

【Example】

Examples 1 to 6 and Comparative Examples 1 to 6 An ingot of tough pitch copper having a thickness of 30 mm, a width of 200 mm and a length of 300 mm was prepared by melting and casting. After subjecting this ingot to hot rolling, cold rolling and intermediate annealing were repeated several times to complete the final intermediate annealing and obtain a copper plate having a thickness shown in Table 1. Then, the copper foil was subjected to cold rolling so that the degree of cold working became the value shown in Table 1, and an ultrathin copper foil having a final thickness of 9 μm or 7 μm was obtained. Then, finish annealing was performed under the conditions described in Table 1 to obtain an ultrathin soft copper foil. The recrystallization temperature of the ultra-thin copper foil used in each example was as shown in Table 1.

[0013]

[Table 1]

The tensile strength (kgf / mm ² ) and elongation (%) of the ultrathin soft copper foil obtained by the above method were as shown in Table 1. In addition, the measuring method of tensile strength and elongation is as follows. That is, both ends of a 10 mm wide sample (the longitudinal direction is the rolling direction) are gripped with chucks,
A sample is pulled at a distance between chucks of 50 mm and a tensile speed of 10 mm / min until the sample breaks, draw a load-strain curve, and the maximum load divided by the cross section is defined as the tensile strength (kgf / mm ² ). On the other hand, if the length of the sample at break was L ₁ and (mm), and _{[(L 1 -50) / 50} ] extending what is calculated by the equation × 100 (%).

As is clear from the results of tensile strength and elongation in Table 1, the degree of cold work in the cold rolling step performed between the final intermediate annealing and the finish annealing is set to 95% or less, and the finish annealing is performed. The ultra-thin soft copper foil (Examples 1 to 6) obtained by performing the temperature at a recrystallization temperature or a temperature higher than the recrystallization temperature by a fixed value,
Ultra-thin soft copper foil obtained by finishing at a cold working degree of more than 95%, performing annealing at a temperature lower than the recrystallization temperature, or performing annealing at a temperature higher than the recrystallization temperature by a fixed value or more Compared with Examples 1 to 6, the tensile strength was high and the elongation was high.

[0016]

The ultra-thin soft copper foil obtained by the method according to the present invention is
The reason for maintaining high tensile strength and maintaining high elongation is not clear, but can be estimated as follows. That is, a copper plate made of tough pitch copper or oxygen-free copper is excellent in ductility, and therefore generally subjected to a large cold working. However, when a large cold work is performed, the flexibility of the crystal structure is reduced, so that the elongation is reduced and the tensile strength is reduced. On the other hand, even in the case of a copper plate having excellent ductility as in the present invention, if a large cold working utilizing this ductility is not performed, the flexibility of the crystal structure is large, and the ductility is high even after the cold working. It has become. As a result, it can be estimated that an ultrathin soft copper foil having a thickness of 10 μm or less having a relatively high tensile strength and a relatively high elongation can be obtained.

[0017]

As described above, the ultrathin soft copper foil obtained by the method according to the present invention has a relatively high tensile strength and elongation, and is used as a shielding material for covering electric wires. When used, even if high tension is applied to the shield material,
This has the effect that the shielding material is hard to cut. In addition, when laminating with a synthetic resin film, even if high tension is applied to the copper foil, the copper foil is less likely to crack.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H05K 1/09 H05K 1/09 A 9/00 9/00 W (58) Field surveyed (Int.Cl. ⁶ , DB name) C22F 1 / 08 B21B 1/40 B21B 3/00 H01B 7/18 H01B 11/06 H05K 1/09 H05K 9/00

Claims (1)

(57) [Claims] 1. A method for producing an ultrathin soft copper foil having a thickness of 10 μm or less by subjecting an ingot of tough pitch copper or oxygen-free copper to hot rolling, cold rolling, intermediate annealing, and finish annealing.
The degree of cold working by cold rolling performed between the final intermediate annealing and the finish annealing is 95% or less, and the finish annealing temperature (T ° C) is recrystallization temperature ≦ T ° C ≦ (recrystallization temperature +80
° C).