JP2001062504A - Method for manufacturing rolled copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively control softening and strength decrease under ordinary temperature without depending on wall-thinning of a material before final rolling by placing the material to be annealed in a specified temperature range and annealing it before final rolling. SOLUTION: Copper foil is manufactured from a copper material by repeating annealing and rolling. The temperature of the material to be annealed is made 550 to 750 deg.C, and it is annealed before final rolling, and impurity elements deposited in the material are solid-solved in the mother phase of the copper to improve the resistance against softening of the material itself. The annealing before final rolling is for 20 minutes maximum, and after annealing, it is preferable to cool it at the cooling rate of 50 deg.C/min or higher until it reaches 300 deg.C. The copper material is desirably of a plate material made by hot-rolling an ingot of touch pitch copper into a specified thickness. A softening preventive effect is further increased using tough pitch copper containing a very fine amount of oxygen.

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 a rolled copper foil, and more particularly, it is difficult to soften at room temperature.
The present invention relates to a method for producing a rolled copper foil whose strength is not easily reduced.

[0002]

2. Description of the Related Art Ultra-thin copper foil having a thickness of 15 μm is used for a wiring board of a printed circuit board, a current collector of a battery, an electrode of a capacitor, an electromagnetic wave shielding material, a lead frame, and the like. Usually, a copper foil of this type is made of, for example, 200 μm by repeatedly annealing and cold rolling a copper material.
A fabric material having a thickness is manufactured, and in the final rolling process, the material is reduced to, for example, 15 μm.

[0003] The copper foil produced in this way has a high degree of cold work in which the final rolling exceeds 90%, so that high energy is accumulated inside the copper foil. It has the property of undergoing recrystallization and softening at room temperature. The softened copper foil has a reduced strength and elongation, is likely to be broken or wrinkled, and is difficult to handle.

Conventionally, as a countermeasure against this problem, the thickness of the material before final rolling is reduced (Japanese Patent Application Laid-Open No. 10-230303). By reducing the workability of cold rolling by reducing the thickness of the dough material, this reduces the energy stored in the copper foil and tries to suppress the progress of recrystallization. The effect is certainly great.

[0005]

However, according to the method for producing a rolled copper foil based on this method, for example, 15 μm
When trying to obtain a copper foil, if the thickness of the material before final rolling is set to 100 μm, which is half the conventional value, the annealing time increases in inverse proportion to the thickness of the material, so The annealing efficiency is remarkably reduced, and the cost burden is increased.

Further, according to this method, when annealing is continuously performed in a rolling line, there is a problem that the material is easily broken. On the other hand, in order to avoid this, the coil wound material is annealed in a furnace. In some cases, there is also a problem in manufacturing, such as the material sticking between the winding layers.

Although the method of reducing the thickness of the material before the final rolling is effective in preventing the strength of the copper foil from decreasing, it is disadvantageous from the viewpoint of manufacturing cost and manufacturing technology. In reality, this is a difficult method to adopt.

Accordingly, an object of the present invention is to produce a rolled copper foil capable of effectively suppressing softening at room temperature and resulting reduction in strength without depending on thinning of the material before final rolling. It is to provide a method.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for producing a rolled copper foil for producing a copper foil having a predetermined thickness from a copper material by repeating annealing and rolling to achieve the above object. The temperature of the material to be annealed is 550-750
The present invention provides a method for producing a rolled copper foil, wherein annealing before final rolling is carried out at a temperature of ℃.

In the present invention, the annealing temperature before final rolling 55
The temperature of 0 to 750 ° C. is much higher than the temperature of 200 to 500 ° C. generally used for annealing of rolled copper foil. The reason for performing the annealing before the final rolling at such a high temperature is that the impurity element precipitated in the base material is dissolved in the copper matrix to improve the softening resistance of the base material itself. That's why.

Usually, the impurity element contained in copper is present in the form of a solid solution at the atomic level in the mother phase of copper, and is precipitated in the form of only impurity atoms or a compound phase such as an oxide. In some cases, impurities such as S have the property of suppressing the softening phenomenon when present in a solid solution state in the copper matrix, while having the characteristic of having no suppression effect in the precipitated state. . Also, the higher the temperature, the more the amount of impurities that can be dissolved in the matrix increases.Therefore, if the dough material is heated to a high temperature and then cooled at a rate at which precipitation does not proceed, the material in which more impurities are dissolved in the solid solution than usual is obtained. Obtainable.

The present inventors have studied the relationship between the annealing conditions of rolled copper foil and the softening characteristics after rolling from the above viewpoints, and solved the softening phenomenon at room temperature, which is a problem in thin rolled copper foil, It has been found that setting the temperature of the base material to 550 to 750 ° C. and performing annealing before final rolling is a condition for suppressing the softening phenomenon and the decrease in strength at room temperature.

When the temperature of the base material is lower than 550 ° C., the solid solution of the impurities in the mother phase does not progress and the precipitation proceeds, so that the softening phenomenon at normal temperature occurs. If the temperature exceeds 750 ° C., the crystal structure after annealing becomes coarse and the mechanical properties deteriorate.

[0014] It is preferable to set a short time for keeping the material at 550 to 750 ° C. As the holding time at a high temperature becomes longer, the crystal becomes coarser. To avoid this phenomenon, the holding time at the above temperature is 2
Should be 0 minutes.

It is desirable that the dough material after being heated to 550 to 750 ° C. be cooled rapidly, and the temperature be lowered to 300 ° C. at a rate of 50 ° C./min or more. If the cooling rate is lower than 50 ° C./min, the precipitation of impurity elements will occur in the temperature range of 300 to 500 ° C., and the softening resistance given by annealing at a high temperature will be lost.

The softening prevention effect according to the present invention appears significantly when tough pitch copper containing a trace amount of oxygen is used as a copper material. Rolled copper foil with tough pitch copper as a constituent material has a particularly large softening phenomenon at room temperature as compared with rolled copper foil with oxygen-free copper or the like as a constituent material.Therefore, the present invention relates to the production of rolled copper foil with tough pitch copper. When applied, the effect is significant.

The rolled copper foil produced according to the present invention can be used in many applications because the strength is hardly reduced. For example, a wiring layer of a printed circuit board laminated with an insulating plate, a wiring layer of a flexible printed circuit board bonded to an insulating film, an electrode of a capacitor, a shielding material for electromagnetic waves, a current collector for a battery whose surface is coated with an active material, or Many applications utilizing its rigidity, such as a lead frame material for mounting a semiconductor chip, can be considered.

[0018]

Next, an embodiment of a method for producing a rolled copper foil according to the present invention will be described.

EXAMPLE 1 About 300 ppm of oxygen and 99.
A 12mm thick copper material is manufactured by hot rolling a tough pitch copper ingot occupying 9% by weight or more,
Next, by repeating annealing and cold rolling, the thickness 2
A 00 μm pre-rolled material was produced.

Next, the material is subjected to an annealing treatment in which the material is heated to 600 ° C. and held at that temperature for 10 minutes, and then cooled to 300 ° C. at a rate of 50 ° C./min or more. This was cold-rolled to a thickness of 15 μm to produce a predetermined rolled copper foil.

[0020]

Example 2 A given rolled copper foil was manufactured by setting the same conditions as in Example 1 except that the temperature of the material during annealing was set to 650 ° C.

[0021]

Conventional Example 1 In Example 1, a predetermined rolled copper foil was produced by setting the temperature of the material at the time of annealing to 400 ° C. and setting the other conditions the same.

[0022]

Conventional Example 2 In Example 1, a predetermined rolled copper foil was manufactured by setting the temperature of the material at the time of annealing to 500 ° C. and setting the other conditions the same.

[0023]

Conventional Example 3 In Example 1, the temperature of the material during annealing was set to 500 ° C. and the cooling rate after annealing was set to 1
A predetermined rolled copper foil was manufactured by setting the temperature to 0 ° C./min and the other conditions being the same.

[0024]

COMPARATIVE EXAMPLE In Example 1, a predetermined rolled copper foil was produced by setting the temperature of the material at the time of annealing to 800 ° C. and setting the other conditions the same.

Table 1 shows the characteristic test results of the rolled copper foil obtained in each of the above examples. It shows the change over time in tensile strength when each sample was left at room temperature, and shows the tensile strength immediately after rolling, three months, six months, and 12 months after rolling. Table 2 shows the measurement results of the crystal grain size after annealing in Examples 1 and 2 and Comparative Example.

[0026]

[Table 1]

[0027]

[Table 2]

According to Table 1, the change with time of the tensile strength in Examples 1 and 2 was moderate, and the residual ratio of the tensile strength after 12 months was maintained at a high level of 85% and 95%, respectively. In contrast, the tensile strength residual ratios of Conventional Examples 1 to 3 after 12 months are remarkably low at 51 to 60%, and a remarkable difference is recognized between the two.

According to Table 2, the comparative examples deviating from the numerical values of the present invention show that the crystal grain size is significantly increased after annealing. It has been shown to have a good particle size. Table 1 and Table 2
In order to prevent a softening phenomenon and a decrease in strength due to the phenomenon, and to obtain a rolled copper foil having a high-quality crystal structure, it is important to set the temperature of the base material in annealing before final rolling to 550 to 750 ° C. The effect of the present invention is clearly shown.

[0030]

As described above, according to the method for producing a rolled copper foil according to the present invention, the annealing before the final rolling is performed so that the material to be annealed is at 550 to 750 ° C. The resulting copper foil has a property that it is hard to soften at room temperature, and therefore, it is possible to provide a rolled copper foil with less decrease in strength.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 692 C22F 1/00 692A 692B (72) Inventor Takeshi Shimada 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Co., Ltd. System Materials Laboratory F-term (reference) 4E002 AA08 AD13 BC07 BD07 BD09 CA08

Claims (4)

[Claims] 1. A method for manufacturing a rolled copper foil for manufacturing a copper foil having a predetermined thickness from a copper material by repeating annealing and rolling, wherein the temperature of the material to be annealed is 550 to 750 ° C. And performing annealing before final rolling. 2. The method according to claim 1, wherein the annealing before the final rolling is performed for a maximum of 20 minutes. 3. The cooling rate of the dough material after annealing before the final rolling until reaching a temperature of 300 ° C. is reduced to 50 ° C.
2. The method for producing a rolled copper foil according to claim 1, wherein the cooling is performed at a rate of not less than / min. 4. The method for producing a rolled copper foil according to claim 1, wherein said copper material is a sheet material having a predetermined thickness obtained by hot rolling an ingot of tough pitch copper.