WO2008050584A1

WO2008050584A1 - Rolled copper foil excellent in bending resistance

Info

Publication number: WO2008050584A1
Application number: PCT/JP2007/069177
Authority: WO
Inventors: Keisuke Yamanishi; Atsushi Miki
Original assignee: Nippon Mining & Metals Co., Ltd.
Priority date: 2006-10-24
Filing date: 2007-10-01
Publication date: 2008-05-02
Also published as: JP4704474B2; JPWO2008050584A1

Abstract

A rolled copper foil excellent in bending resistance is characterized in that a texture having a bent slip band is formed by 50% or more on the surface of the rolled copper foil. The rolled copper foil excellent in bending resistance is characterized in that a texture has an average crystal particle size exceeding 20 μm and satisfies a relation I(200)/Io(200)>40, where I(200) is the integration strength of (200) face determined by X ray diffraction on the rolled surface of the rolled copper foil after recrytallization annealing, and Io(200) is the integration strength of (200) face of fine powder copper determined by X ray diffraction. In particular, a rolled copper foil for flexible printed wiring board (FPC) excellent in bending resistance is provided.

Description

Specification

Rolled copper foil with excellent bending resistance

Technical field

TECHNICAL FIELD [0001] The present invention relates to a rolled copper foil having excellent bending resistance that can be applied to a flexible printed circuit board (FPC).

Background art

A printed wiring board is manufactured by etching a copper foil of a substrate to form various wiring patterns, and connecting and mounting electronic components with solder. Copper foils are classified into electrolytic copper foils and rolled copper foils because of their production methods, and copper foils with excellent bending resistance have been used favorably as copper foils for flexible substrates.

Flexible printed wiring boards (hereinafter referred to as FPC) are used as wiring materials for electronic devices because they are thin and have excellent bendability. Furthermore, the FPC plant continues to expand and grow as electronic devices become lighter, shorter, and more sophisticated. FPC application fields are also expanding rapidly from conventional HDDs, digital cameras, etc., in recent years to LCDs and mobile phones.

In response to the demands of the FPC plant that progresses rapidly like this, the development of a rolled copper foil with even higher bending resistance is required.

[0003] Looking at the advanced technology of FPC, first, there is a demand for products that narrow the bending diameter. In other words, as the electronic equipment becomes lighter, shorter, and more functional, the bending diameter is rapidly becoming narrower. For example, as shown in Fig. 1, new foldings such as cranks and slides that have hinges that are only available with the conventional α type have also appeared in mobile phones, and the FPC has higher tightness, bendability, and bending reliability than before. Requested! /

In addition, FPC is required to be flexible. It is expected to improve workability and save space by making it easier to bend. Also, the softer the FPC inside the HDD, the easier it is to reduce the FPC driving force. As a result, power consumption can be reduced, which leads to HDD power saving. In LCD applications, etc., it can be expected to reduce failures due to springback when bent slightly. As the bend diameter narrows, the soft FPC The demand for is getting higher.

[0004] FPC wiring density (due to high functionality, multi-function, mopile etc.)

Is progressing rapidly! The finest 30 am pitch is expected to be further refined toward a further 20 μm pitch. In the further refinement of FPC wiring, it is also important to develop copper foil including surface treatment that is not just the development of polyimide adhesive. Due to the downsizing of electronic equipment and the influence of lead-free solder, the heat resistance requirements of FPC are further increasing. Looking ahead to the future automotive FPC, the required level of heat resistance is expected to continue to rise.

The above is the force that outlines the future required characteristics of rolled copper foil from the market perspective. In particular, due to the FPC technology trend described above, the reliability of bending of the rolled copper foil has become a problem.

[0005] The following introduces the prior art. For example, when producing rolled copper foil of tough pitch copper or oxygen-free copper, the average grain size was set to 30 or less in recrystallization annealing immediately before the final rolling, and then rolled and measured by X-ray diffraction of the rolled surface ( 200), (220), (311), and (111) planes with diffraction intensities of 3 ≤1 / 1 ≤10,1 / 1 ≤1, I / 1 ≤1,1 / 1 ≤1 (I: Measure

(200) 0 (200) (220) 0 (220) (311) 0 (311) (111) 0 (111) (hkl)

X-ray diffraction integrated intensity of (hkl) plane, I: X-ray diffraction integrated intensity of (hkl) plane measured with fine copper powder

0 (hkl)

There is a proposal of a rolled copper foil in which a cube texture developed under the condition satisfying the degree relationship and rolled at a final rolling degree of 93% or more in the following! (See, for example, Patent Document 1). This itself is a force aimed at improving the flexibility, but the effect is not necessarily expected, and there is a problem that the number of bending is sufficient.

[0006] Also, in rolled copper foil for flexible printed circuit boards! /, The strength I of the surface obtained by X-ray diffraction of the rolled surface (200) was obtained by X-ray diffraction of fine powder (200) For surface strength I, I / I> 20

A technique for making a cubic texture of 0 0 is disclosed (see Patent Documents 2 and 3). Since these technologies do not focus on the force slip band, which is an improvement in flex life, it has been found that this alone does not always provide the desired high flexibility. All of the above technologies are intended to improve the flexibility, but there is a problem that a great improvement in flexibility cannot be expected because there is no focus on the slip band described later.

Yes

Patent Document 1: Japanese Patent Laid-Open No. 2001-323354 Patent Document 2: Japanese Unexamined Patent Publication No. 2000-212661

Patent Document 3: Japanese Patent No. 3009383

Disclosure of the invention

Problems to be solved by the invention

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a rolled copper foil excellent in bending resistance that can be applied to a flexible printed wiring board (FPC). It is to provide.

Means for solving the problem

[0008] As described above, the present application provides the following inventions.

1) Provide a rolled copper foil with excellent bending resistance characterized by having a structure in which a slip band after bending the rolled copper foil is formed on the surface of the rolled copper foil by 50% or more! / . 2) The slip band must have a structure that forms 80% or more on the surface of the rolled copper foil. 3) The slip band must have a structure that forms 90% or more on the surface of the rolled copper foil. Is desirable. Further, the slip band structure formed at the time of bending is preferably uniformly distributed over the entire surface of the copper foil. The present invention is that the slip band is an index that directly indicates the high flexibility of the rolled copper foil. As a result, the number of flexures can be greatly increased as will be described later.

[0009] 4) The integral strength (I) of the (200) plane obtained by X-ray diffraction on the surface of the rolled copper foil after recrystallization annealing is

(200)

, The integrated intensity (I) of (200) plane obtained by X-ray diffraction of fine powder copper is o (200) (200) o (200) with I / \> 40, and the average grain size is 20 m It is an effective structure to obtain a rolled copper foil having excellent bending resistance. Thus, when the (200) plane having a large crystal grain size is highly oriented, a slip band appears remarkably. 5) 1 / \〉 65 in particular

(200) o (200)

desirable. 6) It is more effective to have a structure with an average crystal grain size of 30 m or more. The larger the crystal grains, the more the grain boundaries are reduced, and the force S reduces the misalignment of crystal orientations.

[0010] When copper is rolled at a high degree of workability and is recrystallized, a cubic orientation develops as the recrystallized texture. The cube orientation is the orientation in which the crystal 002> direction is parallel to the rolling direction, the normal direction of the rolling surface, and the width direction. In this case, the {200} plane on the rolling surface (thinned surface) Are oriented. As the cube orientation develops, the abundance ratio of the crystal grains having the cube orientation increases. When the cube orientation is extremely developed, most of the crystal grains show the cube orientation.

In this case, since each crystal grain is oriented in the same direction, it has a structure like a single crystal and the number of grain boundaries decreases. Therefore, in a copper foil having a developed cubic texture, the crystal grain size becomes large, and the force S can be obtained by obtaining a suitable condition that the number of grain boundaries can be reduced.

[0011] The rolled copper foil of the present invention having the above structure and excellent in bending resistance is: 7) The number of times of bending in the IPC sliding bending test (bending radius: 1.5 mm) on the rolled copper foil 1811 m foil is 50000 times or more. Achieving power S. The present invention includes all of these.

As described above, when a copper foil for a flexible substrate having a developed cubic texture is used, the slip band formed on the surface of the copper foil is also an index of bending resistance. The rolled copper foil on which such a slip band is formed can greatly improve the bending resistance!

The invention's effect

[0012] According to the present invention, it is possible to obtain an excellent effect that a rolled copper foil excellent in bending resistance that can be applied to a flexible printed wiring board (FPC) can be realized within a range of industrially acceptable manufacturing costs. .

Brief Description of Drawings

FIG. 1 is a diagram showing diversification of a hinge part of a mobile phone.

FIG. 2 is a diagram showing the IPC sliding bending test result when the bending radius is changed.

FIG. 3 is a diagram (SEM image) showing an observation result of a copper foil surface slip band after bending.

FIG. 4 is a diagram showing the results of an IPC sliding bending test on a two-layer copper-clad laminate.

FIG. 5 is a diagram showing the MIT refraction resistance test results of a two-layer copper-clad laminate.

FIG. 6 is a diagram showing the IPC sliding bending test result of a copper clad laminate when the circuit width is changed.

FIG. 7 is a diagram showing the distribution of the number of bendings when the type of copper foil is changed.

[Fig. 8] A diagram showing the results of an MIT refraction test in which the influence of the rolling direction of the copper foil was examined. FIG. 9 is a diagram showing the IPC sliding bending test result of copper foil at high temperature.

FIG. 10 is a diagram showing test results of loop stiffness of copper foil.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Currently, the rolled copper foils that are produced are FPC wiring materials that have a certain degree of bending reliability, but there is a demand for wiring materials that have even higher bending properties.

Regarding the relationship between the bending radius and the number of sliding bends in the copper foil, if the bending radius is small, the force and strain are increased on the copper foil, and the flexibility is lowered. For this reason, for example, electrolytic copper foil has the lowest bendability, making it difficult to adapt to products with a small bending radius. Even in the conventional (current) rolled copper foil with high bendability, if the bend radius is reduced, the number of bends is drastically reduced and it becomes very severe.

Fig. 2 shows the test results of the number of bendings of the rolled copper foil of the present invention (the rolled foil of the present invention), the electrolytic copper foil, and the conventional (current) rolled copper foil. As shown in FIG. 2, the rolled copper foil of the present invention (the invention-invented rolled foil) has a significantly increased number of bending times compared to the electrolytic copper foil and the conventional rolled copper foil. The slip band is an index that directly indicates the high flexibility of the rolled copper foil.

[0015] When producing a rolled copper foil having excellent bending resistance according to the present invention, the integral strength (I) of the (200) plane obtained by X-ray diffraction of the surface of the rolled copper foil after recrystallization annealing is very small. X-ray diffraction of powder copper

(200)

The integrated intensity (I) of the (200) plane is I / \> 40 and the average grain size is 20

o (200) (200) o (200)

Strength to make the structure over 11 m Effective for forming a slip band after bending a rolled copper foil. When the X-ray diffraction intensity (I) of the (200) plane parallel to the rolling surface and the X-ray diffraction intensity (Io) of the (200) plane of powdered copper (random orientation) are measured under the same conditions, the development of the cube texture The degree of can be evaluated by the ratio I / Io of these X-ray diffraction intensities.

[0016] The development of the cube texture depends on the processing that leads to the final cold rolling not only by the final cold rolling rate, the heat treatment process, the final annealing temperature, the chemical composition of copper, the impurity content, and the like. Therefore, in order to obtain the target I / Io value, it is necessary to determine the optimum final cold rolling ratio in accordance with the material copper to be used and the processing process.

As the rolled copper foil, copper whose recrystallized aggregate structure has a cubic orientation can be used. Typical examples of this material include tough pitch copper and oxygen-free copper.

In general, copper added with alloying elements is not suitable because it inhibits the development of cube orientation. . However, the addition of a minute alloy element of about 0.1 wt%, such as tough pitch copper adjusted for softening temperature by adding Ag or the like, has no particular problem in use because it does not hinder the development of the cube orientation.

[0017] (High flexibility mechanism of rolled copper foil)

The present inventor researched and developed various types of rolled copper foils in order to provide flex resistance that can be applied to flexible printed circuit boards (FPC). It is a component that there is a phenomenon of. That is, a large amount of bent slip bands are generated on the surface of the rolled copper foil!

Fig. 3 shows the SEM image of the S-side of the copper foil circuit after bending the FPC of the rolled copper foil of the present invention (rolled foil of the present invention). The upper structure (SEM image) in Fig. 3 shows a (200) orientation force of 9% on the surface and I / \ = 75. Compared with the part other than the bend, a fine streak pattern was observed on the surface. The streak pattern shown in this figure is the so-called “slip band”. This is a phenomenon peculiar to highly crystalline (single crystal) metals. In this case, slip bands occurred at 90% of the surface.

[0018] When a single crystal metal is repeatedly subjected to stress, a slip band is generated on the metal surface in an attempt to relieve strain (dislocation) accumulated in the grain boundary. The middle structure (SEM image) in Fig. 3 shows the case where the (2 00) orientation force of the surface is 0% and I / \ = 10. In the middle figure of Fig. 3, it can be observed that a slip band is partially generated. In this case, slip bands occurred at 35% of the surface. In this case, since a slip band is generated, the force showing a slightly good bending resistance is not sufficient.

On the other hand, in the lower structure (SEM image) in Fig. 3, the (200) orientation force of the surface is ¾0%, and I / \

This is the case of 3. This is the force of electrolytic copper foil. The electrolytic copper foil has almost no slip band on the surface. As a result, it can be seen that even when repeated stress is applied as in the case of the rolled copper foil, even cracks are generated.

[0019] Thus, the slip band is generated in the rolled copper foil because the rolled copper foil is highly oriented in the (200) plane having high crystallinity like a single crystal. A slip band is generated after repeated bending.

This is a phenomenon that alleviates fatigue accumulation inside the rolled copper foil during bending. In particular, the rolled copper foil can have high flexibility. That is, if a large amount of slip bands can be generated after the copper foil is bent, the bending resistance of the rolled copper foil can be greatly improved.

It is desirable that the slip band after repeated bending should have a structure that forms 50% or more. In addition, it is preferable to have a structure in which 80% or more, more preferably 90% or more is formed. And it is desirable that the slip band structure formed at the time of bending is uniformly distributed over the entire surface of the copper foil.

[0020] (Mechanism of high flexibility of rolled copper foil of the present invention (rolled foil of the present invention))

There are mainly three reasons why the rolled copper foil of the present invention (rolled foil of the present invention) possesses high flexibility.

(1) High orientation of (200) plane of crystal

The rolled copper foil of the present invention (the present invention rolled foil) has a (200) plane orientation after recrystallization that is nearly 100% higher than that of the conventional rolled copper foil. And I / \〉 40

(200) o (200)

I / \〉 65 has been achieved. From this, the orientation mismatch is extremely large at the grain boundary.

(200) o (200)

Become smaller. For example, in an electrolytic copper foil in which crystals are randomly oriented, there is a large mismatch in the orientation of crystal grain boundaries. This mismatch in crystal orientation affects the accumulation of fatigue (dislocations) at the grain boundaries. Therefore, in the rolled foil of the present invention having a small mismatch, the accumulation of dislocations at the grain boundaries is also reduced, and as a result, it is considered that high flexibility is produced. In the case of having such a structure, it is effective to form a slip band after bending at 50% or more on the surface of the rolled copper foil.

[0021] (2) Grain size

Since the rolled copper foil of the present invention (the rolled foil of the present invention) has a recrystallized crystal grain size that is significantly larger than that of a conventional rolled copper foil, the overall crystal grain boundary is also reduced. On the other hand, the electrolytic copper foil made of fine crystals has remarkably many crystal grain boundaries. In addition, when crack generation / development in bending is along the crystal grain boundary, the rolled foil of the present invention with few crystal grain boundaries has few starting points of crack generation, and as a result, high flexibility is considered to occur. This case is also effective for forming a slip band after bending.

(3) Ease of slip band In the rolled foil of the present invention, slip bands are easily generated due to rolling, annealing, and crystal grain size. In repeated bending, the formation of this slip band is important. As mentioned above, the formation of slip bands alleviates bending fatigue, resulting in high flexibility.

[0022] Regarding the production of the rolled copper foil, the condition that a uniform slip band is formed after repeated bending, that is, the condition that the slip band after bending the rolled copper foil is formed on the surface of the rolled copper foil by 50% or more. If it is, there will be no restriction | limiting in particular, For example, the copper whose recrystallized aggregate structure | tissue of tough pitch copper and an oxygen free copper becomes a cube orientation can be used. This copper ingot is melted, this ingot is hot-rolled from 900 ° C, then cold-rolling and annealing are repeated, and finally a predetermined thickness (for example, 18 Hm thickness, 12 Hm thickness) , 9 μm thick).

After the final cold rolling, the grain size is adjusted to exceed 20 m and further to 30 m by annealing. The larger the crystal grain size is, the more preferable it is to have a crystal grain size exceeding 50 ^ m, and even 100 m and 200 m.

In the final cold rolling, the degree of cube texture is adjusted by changing the rolling degree (R) in various ways. For example, adjust in the range of R = 90-100% (less than). Then, recrystallization annealing is performed at a temperature higher by 50 ° C. than the semi-softening temperature to obtain I / 1> 40, preferably I / \> 65. The I / Io value was measured by the X-ray diffraction (diffractometer) method (hereinafter the same).

R is defined by the following equation.

R = (t—t) / t (t: thickness before rolling, t: thickness after rolling)

Example

Hereinafter, the present invention will be described with reference to examples. In addition, a present Example shows a suitable example, This invention is not limited to these Examples. Accordingly, all modifications and other examples or aspects included in the technical idea of the present invention are included in the present invention. For comparison with the present invention, comparative examples are also described as necessary.

[0024] A tough pitch copper ingot containing 200 ppm of Ag was melted, and this ingot was 900. The plate was hot-rolled from the same to obtain a 10 mm thick plate. Then, cold rolling and annealing were repeated, and finally cold rolled to 9 to 18 m thick copper foil. In the final cold rolling, the grain size is adjusted to the range of 20-100 πι by annealing before the final cold rolling, and the degree of rolling (R) is changed variously in the final cold rolling. Changed the strength of the texture.

In the following examples, R = 98.2%, recrystallization annealing was performed at a temperature 50 ° C. higher than the semi-softening temperature, and I / Io = 40-80. The I / Io value was measured by the X-ray diffraction (diffractometer) method as described above.

Similar results were obtained when oxygen-free copper (HO material) was used as the rolled copper foil material. In the examples, selection of the rolled copper foil material, rolling or heat treatment conditions are not particularly limited, and any range can be selected as long as it is within the range described in the present specification. Therefore, in the following description, details of the rolling process and the heat treatment process are omitted.

Hereinafter, the present invention will be described more specifically by various tests.

[0025] (Slip band evaluation method)

A slip band evaluation method will be described in advance.

[Preparation of test sample]

(1) Using copper foil (lS ^ m thickness, 12 πι thickness) and polyimide sheet with adhesive, make a three-layered copper clad laminate (Copper Clad Laminates: CCL) by thermocompression bonding

Thermocompression bonding conditions: 180 ° C, 60 minutes

(2) Forming a JIS C5016 folding test pattern on a 3-layer copper clad laminate by etching [Bend test]

Conducted 30000 IPC sliding bending tests on test samples

Bending test condition: Bending radius 2.0mm, bending speed 1000 times / min, stroke 20mm, copper foil side set inside

[Observation of slip band]

Check the area ratio of the slip band formation area on the surface of the test sample on a 60 m x 60 m screen of SEM (X 1500)

[0026] (Comparison test of flexibility)

The copper foil used in the above test was used. For the examples of the present application, those having a slip band formation ratio of 64-98% were used, and for the comparative examples, those having a slip band formation ratio of 25-35% were used. . Comparative evaluation of the flexibility of the rolled copper foil of the present invention (in FIG. 4 and FIG. 5, expressed as “rolled foil of the present invention”, the same shall apply hereinafter) and the conventional rolled foil (comparative example) was performed. Bending radius 1. Figure 4 shows the IPC sliding bending test results at 5 mm.

As shown in FIG. 4, in the copper-clad laminate of 18-thick rolled foil, the rolled foil of the present invention showed more than twice as high flexibility as the conventional rolled copper foil. Furthermore, the rolled copper foil of the present invention having a thickness of 12 ^ 01 (the present invention rolled foil) exhibits the highest flexibility, which is about 3 times more excellent than the conventional rolled copper foil of 18πι. Had. In addition, Fig. 5 shows the results of the bending resistance test at a bending radius of 0.8 mm. Similar to the IPC test results, the rolled foil of the 12 ^ 01 invention of the present application showed the highest flexibility.

As described above, the rolled copper foil of the present invention (the rolled foil of the present invention) is a high bending which is several times higher than the conventional rolled copper foil in the IPC sliding bending test and the MIT folding resistance test, which are general bending evaluation methods. Showing sex. The latest model of mobile phone hinges is required to have very high bendability, so this 12 invention rolled foil is optimal.

[0027] (Flexibility comparison test with different circuit widths)

Fig. 6 shows the results of the sliding bending test in which the flexibility of the rolled copper foil of the present invention (the rolled foil of the present invention) and the conventional rolled copper foil was compared by changing the copper foil circuit width. Figure 6 shows that the flexibility decreases when the circuit width is reduced from 1 mm to 0.5 mm. This is because when the circuit width is narrowed, the life from the crack to the disconnection is shortened.

From Fig. 6, compared to the conventional rolled copper foil copper clad laminate (circuit width lmm, right end), the rolled copper foil of the present invention (rolled foil of the present invention) copper clad laminate (circuit width 0.5mm, left end) It can be seen that almost the same flexibility is obtained. That is, even if the circuit width is narrowed by making the circuit finer on the printed wiring board, the rolled foil of the present invention can maintain higher flexibility than the conventional rolled copper foil. In the above, it was carried out with 12 m foil, but even with 9 m foil, the bending resistance can be improved similarly.

[0028] (About variation in flexibility)

FPC market demands require higher standards than ever for flex reliability as well as high flexibility. Therefore, the bending reliability of the rolled copper foil of the present invention (rolled foil of the present invention), the conventional rolled copper foil, and the electrolytic copper foil (A, B) was evaluated. Evaluation was performed at a bending radius of 1.5 mm on 100 copper foil single samples after heat treatment at 180 ° C for 1 hour. Figure 7 shows the frequency distribution of the number of bendings for 100 samples. From Fig. 7, the conventional rolled copper foil shows stable and high flexibility. On the other hand, special electrolytic copper foils vary in the number of flexing times until the copper foil breaks, and are inferior to conventional rolled copper foils in stable bendability. From this, it can be seen that the conventional rolled copper foil is superior in severe bending conditions compared to the conventional electrolytic copper foil!

However, in the case of the rolled copper foil of the present invention (the present invention rolled foil), it can be seen that a more excellent number of bendings can be obtained and the bending reliability is guaranteed as compared with the conventional rolled copper foil.

[0029] (Bending direction reliability)

Since rolled copper foil is rolled in the MD (Machine Direction) direction in the manufacturing process, it is sometimes said that the flexibility of the copper foil differs between the MD direction and the TD (Traversal Direction) direction. Therefore, an MIT folding test in the MD'TD direction was performed on a copper-clad laminate using the rolled copper foil of the present invention. The results are shown in Fig. 8.

From Fig. 8, both the conventional copper clad laminate of rolled copper foil and the copper clad laminate of the rolled copper foil of the present invention (rolled foil of the present invention) showed no difference in flexibility between MD and TD. The same flexibility was exhibited. This shows that the rolled copper foil of the present invention has high bending reliability not only in the MD direction but also in the TD direction.

[0030] (About high temperature flexibility)

The heat load on the FPC is also increasing due to the light, thin and small technology of electronic equipment. Therefore, we evaluated the bending of copper foil, an FPC wiring material, in a high-temperature atmosphere. Figure 9 shows the results of the sliding bending test at 25 ° C and 80 ° C.

From Fig. 9, the conventional rolled copper foil is about 20,000 times at 80 °, which is more than twice as flexible as the electrolytic copper foil about 10,000 times. However, the rolled foil of the present invention has dramatically improved flexibility compared to the conventional rolled copper foil. The number of bends exceeds 70,000 at 25 ° C and 80 ° C, and it is bent 80,000 times. It is close to the number of times. This is about 4 times the conventional rolled copper foil. Thus, it can be seen that there is a marked improvement over the conventional rolled copper foil, and that high flexibility can be maintained even at a high temperature of 80 ° C. as well as only at 25 ° C. (normal temperature).

[0031] (About flexibility)

FPC manufacturers are developing polyimide adhesives for softer FPC market requirements. Naturally, softness is also required for copper foil, which is a wiring material. . Figure 10 shows the results of evaluation of the softness of the rolled copper foil using the loop stiffness test.

From FIG. 10, since the rolled copper foil of the present invention (the rolled foil of the present invention) has a lower stiffness than the conventional rolled copper foil, the rolled copper foil of the present invention (the rolled foil of the present invention) is It can be said that it is softer than conventional rolled copper foil. Therefore, if the rolled foil of the present invention of the present invention is used, it becomes possible to produce an FPC that is softer than the conventional rolled copper foil, so that it is possible to expect power saving due to the ease of folding and the reduction of the driving force of the FPC. In fact, it has a remarkable advantage in applying to the rolled copper foil of the present invention (rolled foil of the present invention) in HDDs and optical pickups.

Industrial applicability

According to the present invention, when a rolled copper foil excellent in bending resistance can be realized within the range of industrially acceptable production costs, an excellent effect can be obtained. Particularly, in the production of a flexible printed wiring board (FPC), It is extremely useful industrially.

Claims

The scope of the claims

[1] A rolled copper foil having excellent bending resistance, characterized in that a slip band after bending the rolled copper foil has a structure in which 50% or more is formed on the surface of the rolled copper foil.

[2] The rolled copper foil having excellent bending resistance according to [1], wherein the slip band has a structure in which 80% or more of the slip band is formed on the surface of the rolled copper foil!

[3] The rolled copper foil having excellent bending resistance according to [1], wherein the slip band has a structure in which 90% or more of the slip band is formed on the surface of the rolled copper foil!

[4] The integrated intensity (I) of the (200) plane obtained by X-ray diffraction on the surface of the rolled copper foil after recrystallization annealing is very small.

(200) The integrated intensity (I) of the (200) plane determined by X-ray diffraction of powdered copper is I / \> 40, and o (200) (200) o (200) The average grain size is 20 The rolled copper foil having excellent bending resistance according to any one of claims 1 to 3, wherein the rolled copper foil has a structure exceeding m! /.

[5] The rolled copper foil having excellent bending resistance according to claim 4, wherein I / \> 65.

(200) o (200)

[6] The rolled copper foil having excellent bending resistance according to claim 4 or 5, which has a structure with an average crystal grain size of 30 m or more! /.

[7] Rolled copper foil 18 ^ 01 Foil IPC sliding bend test (bending radius 1.5mm) is 500 times

The rolled copper foil having excellent bending resistance according to any one of claims 1 to 6, wherein the rolled copper foil has a structure that achieves 00 times or more.