KR101989853B1 - Rolled copper foil - Google Patents

Abstract

[PROBLEMS] To provide excellent bending resistance and excellent bending resistance.
A plurality of crystal planes parallel to the main surface include {022} plane, {002} plane, {113} plane, {111} plane and {133} plane, and the 2θ / The diffraction peak intensity ratio obtained from the used X-ray diffraction measurement and converted to have a total value of 100 is I {022} + I {002}? 80.0, I {111}? 5.0, Of the diffraction peaks of the {111} planes at tilt angles of 47 and 53 degrees when the graphs showing the average intensity of the diffraction peaks of the {111} The intercept is one fourth or more of the maximum value of the average intensity of the diffraction peaks of the {111} plane within the range of the tilt angle of 15 degrees or more and 90 degrees or less.

Description

[0001] ROLLED COPPER FOIL [0002]

The present invention relates to a rolled copper foil, and more particularly to a rolled copper foil used for a flexible printed wiring board.

Flexible Printed Circuits (FPCs) are thin and highly flexible, so they have a high degree of freedom in the mounting form for electronic equipment and the like. Therefore, the FPC can be used as a digital versatile disk (DVD: hard disk drive) as well as a movable part such as a bent part of a folding cellular phone, a digital camera, and a printer head, Digital versatile disk) or a compact disk (CD: Compact Disk). Therefore, a rolled copper foil used as an FPC or a wiring material thereof has been required to have a high flexural characteristic (high flexural characteristic), that is, an excellent flexural resistance (flex resistance) capable of withstanding repeated flexural strength.

The rolled copper foil for FPC is manufactured through processes such as hot rolling and cold rolling. The rolled copper foil is bonded to a base film (base material) of an FPC made of resin (resin) such as polyimide directly or through an adhesive in the subsequent FPC manufacturing process . The rolled copper foil on the substrate is subjected to surface processing (surface processing) such as etching to form a wiring. The bending resistance of the rolled copper foil remarkably improves in the state after annealing after being softened by recrystallization rather than in a hardened state after being rolled and hardened by cold rolling. Therefore, for example, in the above-mentioned manufacturing process of the FPC, the rolled copper foil after the cold rolling is used to cut the rolled copper foil while avoiding deformation such as elongation or wrinkling, and is superposed on the substrate. Thereafter, the rolled copper foil and the substrate are brought into close contact with each other to be integrated by heating in combination with the recrystallization annealing (recrystallization annealing) of the rolled copper foil.

Various studies have been made on a rolled copper foil excellent in bending resistance and a method for producing the same, on the premise of the above-mentioned manufacturing process of the FPC, and the surface of the rolled copper foil has a {002} plane {200 }) Have been reported to improve the bending resistance.

For example, in Patent Document 1, the annealing immediately before the final cold rolling is performed under the condition that the average grain size of the recrystallized grains is 5 占 퐉 to 20 占 퐉. Further, the rolling degree in the final cold rolling is set to 90% or more. The strength of the {200} face of the rolled face obtained from the X-ray diffraction pattern in the state of being tempered so as to be a recrystallized structure is represented by I and the intensity of {200} face of the fine powder copper obtained from the X- When the intensity is I0, a cubic texture (I / I0 > 20) is obtained.

Further, for example, in Patent Document 2, the degree of development of the cube texture before final cold rolling is enhanced, and the degree of processing in final cold rolling is set to 93% or more. Further, by performing the recrystallization annealing, a rolled copper foil having an integrated intensity (I / I0? 40) of a {200} plane and having a significantly improved cubic texture is obtained.

For example, in Patent Document 3, the total degree of processing in the final cold rolling step is set to 94% or more and the degree of processing per pass is controlled to 15% to 50%. Thus, after the recrystallization annealing, a predetermined grain orientation state (crystal grain orientation state) is obtained. That is, the in-plane orientation degree? Of the {111} plane relative to the {200} plane of the rolled surface obtained by X-ray diffraction pole figure measurement (X-ray diffraction pole point measurement) is 10 degrees or less. The ratio of the normalized diffraction peak intensity [a] of the {200} plane and the normalized diffraction peak intensity [b] of the crystal region in the twin crystal relationship of the {200} plane, which is the cube- [a] / [b] ≥ 3.

As described above, in the prior art, the cube texture of the rolled copper foil is developed after the recrystallization annealing step by increasing the total degree of processing of the final cold rolling step, thereby improving the bending resistance.

Japanese Patent No. 3009383 Japanese Patent No. 3856616 Japanese Patent No. 4285526

On the other hand, in recent years, FPCs are folded and assembled in a small space in accordance with miniaturization and thinning of electronic devices. Particularly, in a panel portion of a smart phone or the like, an FPC on which wiring lines are formed may be bent and assembled at 180 degrees. For this reason, there is an increasing demand for a rolled copper foil that has a small bending radius (bending radius) to allow bending resistance.

As described above, different requirements may arise for the bending resistance to withstand repeated bending and the bending resistance to withstand a small bending radius, depending on the difference in purpose. In order to cope with these different demands, conventionally, rolled copper foils of different characteristics have been separately manufactured for each use. However, this situation can not be said to be efficient in terms of productivity, and there is a problem that the profitability is bad.

An object of the present invention is to provide a rolled copper foil which can have high bending resistance and excellent bending resistance after a recrystallization annealing step. When the rolled copper foil having both of these characteristics can be realized, the present invention can be applied to any of applications for emphasizing flex resistance and applications for emphasizing bending resistance. Therefore, the production efficiency can be remarkably improved.

According to the first aspect of the present invention,

(Final cold rolling step) having a main surface (main surface) and having a plurality of crystal planes (crystal planes) parallel to the main surface, and after the recrystallization annealing step (annealing step) (Rolled copper foil)

Wherein the plurality of crystal planes include {022} plane, {002} plane, {113} plane, {111} plane and {133}

The diffraction peak intensity ratios (diffraction peak intensity ratios) of the respective crystal planes obtained from X-ray diffraction measurement (X-ray diffraction measurement) using the 2θ / θ method on the main surface so as to have a total value of 100 were defined as I {022 }, I {002}, I {113}, I {111} and I {133}

I {022} + I {002}? 80.0,

I {111}? 5.0,

The X-ray Pole-figure method is used and, for each of a plurality of tilt angles in a range of 15 degrees or more and 90 degrees or less, an in-plane rotation angle of the main surface is set to a range of 0 degrees to 360 degrees The average intensity of the diffraction peaks of the {111} plane measured by varying was obtained,

When a graph showing the average intensity of the diffraction peaks of the {111} plane was prepared with the tilt angle as the horizontal axis and the diffraction peak intensity as the vertical axis,

A straight longitudinal axis section connecting the average intensity of the diffraction peak of the {111} plane at the tilt angle of 47 degrees and the average intensity of the diffraction peak of the {111} plane at the tilt angle of 53 degrees, Is one fourth or more of the maximum value of the average intensity of the diffraction peaks of the {111} plane within the range of the tilt angle of 15 degrees or more and 90 degrees or less.

According to the second aspect of the present invention,

Which is mainly composed of oxygen-free copper or tough-pitch copper (TPC)

There is provided a rolled copper foil as described in the first aspect.

According to the third aspect of the present invention,

Silver, at least one of boron, titanium, and tin is added

There is provided a rolled copper foil as described in the first or second aspect.

According to the fourth aspect of the present invention,

Having a thickness of 20 μm or less

There is provided the rolled copper foil according to any one of the first to third aspects.

According to the fifth aspect of the present invention,

And the total working degree in the final cold rolling step is not less than 90%

There is provided the rolled copper foil according to any one of the first to fourth aspects.

According to the sixth aspect of the present invention,

For flexible printed wiring board

There is provided the rolled copper foil according to any one of the first to fifth aspects.

According to the present invention, there is provided a rolled copper foil capable of providing excellent bending resistance and excellent bending resistance after a recrystallization annealing step.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flowchart showing a manufacturing process of a rolled copper foil according to an embodiment of the present invention. FIG.
2 is a diagram showing an outline of a method of measuring X-ray diffraction in the examples and comparative examples of the present invention.
(A) is an X-ray diffraction chart of a rolled copper foil according to Example 1 of the present invention, and (b) is an X-ray diffraction chart of a rolled copper foil according to Example 2, (C) is an X-ray diffraction chart of a rolled copper foil according to Comparative Example 1. Fig.
4 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 1 of the present invention.
5 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 2 of the present invention.
6 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 3 of the present invention.
7 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 4 of the present invention.
8 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 5 of the present invention.
9 is a graph showing the average intensity of the diffraction peaks of the {111} plane in Comparative Example 1.
Fig. 10 is a graph showing the average intensity of diffraction peaks of the {111} plane in Comparative Example 2; Fig.
Fig. 11 is a graph showing the average intensity of diffraction peaks of the {111} plane in Comparative Example 3; Fig.
12 is a graph showing the average intensity of diffraction peaks of the {111} plane in Comparative Example 4.
13 is a graph showing the average intensity of diffraction peaks of the {111} plane in Comparative Example 5.
14 is a schematic view of a sliding bending test apparatus for measuring the bending resistance of a rolled copper foil according to an embodiment of the present invention.
15 is a diagram showing an outline of a method of testing the bendability of a rolled copper foil according to an embodiment of the present invention.
16 is a graph showing the average intensity of diffraction peaks of the {111} plane according to Example 6 of the present invention.
17 is a graph showing the average intensity of diffraction peaks of the {111} plane in Comparative Example 6.
18 is a graph showing the average intensity of the diffraction peaks of the {111} plane in Comparative Example 7.
Fig. 19 is an inverse pole diagram of a pure metal. Fig. 19 (a) is an inverse pole diagram showing a crystal rotation direction due to tensile deformation, and Fig. 19 (b) . ≪ / RTI >
Fig. 20 is a diagram showing regions of {013} plane, {023} plane and regions of crystal planes in which a difference in orientation between these crystal planes is relatively small.

≪ Knowledge obtained by the present inventors &

As described above, it is better to develop the cubic orientation of the rolled surface in order to obtain a rolled copper foil with excellent bending resistance (bending resistance) required for FPC applications. The present inventors have also conducted various experiments to increase the occupancy of the cubic bearing. From the results of the experiments so far, the {022} plane existing after the final cold rolling step (final cold rolling step) is tempered by recrystallization by the subsequent recrystallization annealing step (recrystallization annealing step) Plane, that is, the {002} plane. That is, after the final cold rolling step and before the recrystallization annealing step, it is preferable that the {022} plane be the kitchen orientation (main orientation).

On the other hand, as described in the above Patent Documents 1 to 3, and as attempted by the inventors of the present invention, in the rolled copper foil having a polycrystalline structure, the {002} plane as the cube aggregate structure occupies 100% There is no case. This is also the case before the recrystallization annealing step. In the state before the recrystallization annealing step, in addition to the {002} plane on which the crystal orientation is maintained before and after recrystallization, the {111} plane, the { {013}, the crystal planes of the dihedral such as the {023} plane are not controlled and plural crystals are mixed. It is considered that the crystal grains (crystal grains) having a plurality of crystal planes thereof have various influences on various characteristics of the rolled copper foil. Therefore, the inventors of the present invention have focused on the crystal face of the unidirectional which has been considered to be unnecessary so far, and while maintaining the high bending resistance without decreasing the occupancy rate on the kitchen, the bending resistance of the rolled copper foil by the crystal faces of these sub- And whether or not it can be increased.

In this study, the inventors of the present invention have found that the diffraction efficiency of the diffraction grating on the main surface of the rolled copper foil of each crystal face including the {113} plane, {111} plane, {133} plane, {013} plane, {023} We proceeded to interpret the peak. The diffraction peaks (diffraction peaks) indicate the presence of each of the diffractions, and the occupancy rate of each diffraction peak can be known from the intensity ratio. As a result of such studies, the inventors of the present invention found that among the respective crystal planes of these cuboids, there is a tendency to lower and improve the bending resistance of the rolled copper foil. Therefore, if the occupation rate of these negative directions can be controlled based on the information obtained from the diffraction peak on the main surface of the rolled copper foil, it is possible to provide the rolled copper foil after the recrystallization annealing process with high bending resistance and excellent bending resistance . The present inventors have variously defined the states of the diffraction peaks and found a method of controlling them. Accordingly, high bending resistance can be obtained by controlling the {022} plane on the kitchen, and the bending resistance can be further improved.

The present invention is based on this finding found by the inventors.

≪ One embodiment of the present invention &

(1) Construction of rolled copper foil

First, the structure of the rolled copper foil according to one embodiment of the present invention will be described.

(Outline of rolled copper foil)

The rolled copper foil according to the present embodiment is, for example, in the form of a plate having a rolled surface as a main surface. This rolled copper foil can be produced, for example, from a copper ingot made of pure copper as a raw material such as oxygen-free copper (OFC: Oxygen-Free Copper) or TPC (Tough-Pitch Copper And is a rolled copper foil after a final cold rolling step which is performed by a hot rolling step or a cold rolling step to a predetermined thickness and before a recrystallization annealing step.

The rolled copper foil according to the present embodiment is configured to be used, for example, as a flexible wiring material for FPC. That is, a total cold workability of not less than 90%, more preferably not less than 94%. Such a rolled copper foil, as described above, is also subjected to a recrystallization annealing step, for example, a step of bonding the base material of an FPC, and is recrystallized to provide excellent bending resistance.

The oxygen-free copper used as the raw material is, for example, a copper material having a purity of 99.96% or more as stipulated in JIS C1020, H3100 and the like. The oxygen content may not be completely zero. For example, oxygen may be contained in the order of several ppm. The tough pitch copper is, for example, a copper material having a purity of 99.9% or more as specified in JIS C1100, H3100 and the like. In the case of tough pitch copper, the oxygen content is, for example, about 100 ppm to 600 ppm. In some cases, a rolled copper foil is prepared by adding a small amount of a predetermined additive such as silver (Ag) to these copper materials to form a rare copper alloy and adjusting various characteristics such as heat resistance. The rolled copper foil according to the present embodiment can include both pure copper and a lean copper alloy and hardly affects the effect of the present embodiment by the copper material and the additive of the raw material.

The total machining degree in the final cold rolling step is TB (total thickness) (%), where TB is the thickness of the object to be processed (copper plate material) before the final cold rolling step and TA is the thickness of the object after the final cold- = [(TB-TA) / TB] X 100. By setting the total working degree to not less than 90%, more preferably not less than 94%, a rolled copper foil excellent in flex resistance can be obtained.

(Crystal structure of rolled surface)

The rolled copper foil according to the present embodiment has a plurality of crystal planes parallel to the rolled surface. Specifically, in the state after the final cold rolling step and before the recrystallization annealing step, the plurality of crystal planes include {002} plane, {002} plane, {113} plane, {111} plane and {133} plane. The {022} plane is above the surface of the rolled surface, and the other crystal planes are sub-directions.

As described above, the state of each of these crystal planes is controlled by a proportional relation in which the states such as the diffraction peak intensity measured for each crystal plane are variously defined. The diffraction peak intensity of each crystal plane can be obtained from X-ray diffraction measurement using the 2? /? Method on the rolled surface of the rolled copper foil. Here, the X-ray diffraction measurement using the 2? /? Method will be described with reference to Fig. 2 related to Examples and Comparative Examples described later. Note that the description here is only schematic, and the details will be described later.

As shown in Fig. 2, a sample piece (sample piece) 50 such as a rolled copper foil is rotatably arranged around three scanning axes of the? Axis,? Axis, and? Axis. In the X-ray diffraction measurement using the 2? /? Method, the sample piece 50 is rotated about the? -Axis, and the incident X-ray is incident on the sample piece 50 at an angle?. And detects a diffracted X-ray bent at an angle (2 &thetas;) with respect to the incident direction of the incident X-ray. Accordingly, the diffraction peaks of the respective crystal planes parallel to the main surface of the sample piece 50 are obtained with the strength corresponding to the occupancy of each crystal plane on the main surface.

The diffraction peak intensities of the five crystal planes measured by the X-ray diffraction are expressed as ratios of the diffraction peak intensities of the respective crystal planes in terms of the ratio at which the total value is 100. [ This diffraction peak intensity ratio is approximately the same as the occupation rate of each crystal plane on the rolled surface.

From the diffraction peak intensity of each crystal plane, a conversion formula (A) for obtaining the diffraction peak intensity ratio of the {022} plane as a representative is shown below. The diffraction peak intensities of the respective crystal planes are I '{022}, I {002}, I {113}, I {111} and I {133} , I '{002}, I' {113}, I '{111}, and I' {133}.

[Number 1]

In the rolled copper foil according to the present embodiment, the diffraction peak intensity ratio of the {022} plane and the {002} plane is such that the following equation (1) holds for example.

I {022} + I {002}? 80.0 ... (One)

In the rolled copper foil of the present embodiment, for example, the following formula (2) holds for the diffraction peak intensity ratio of the {111} face.

I {111}? 5.0 ... (2)

The rolled copper foil according to the present embodiment is specified to satisfy the numerical values obtained by using the X-ray Pole Figure method in addition to the above equations (1) and (2). Here, the measurement using the X-ray Pole-figure method will be described with reference to Fig. Note that the description here is only schematic, and the details will be described later.

2, in the measurement using the X-ray Pole-figure method, the sample piece 50 is further rotated around the ψ-axis to obtain a plurality of tilt angles ψ The diffracted X-rays are detected similarly to the 2? /? Method. At this time, with respect to each tilt angle?, The sample piece 50 is rotated around the? -Axis while maintaining the angle so that the in-plane rotation angle? Is within a range of 0 to 360 degrees And the average intensities of diffraction peaks of the {111} plane of the obtained copper crystals are respectively determined.

A method of defining the rolled copper foil according to the present embodiment using the average strengths obtained by these measurements will be described below.

The average intensity of the diffraction peaks of the {111} plane is shown with the tilt angle psi as the horizontal axis and the diffraction peak intensity as the vertical axis. For example, the graph shown in Fig. 4 relating to Example 1 do.

For example, as shown in FIG. 4, when the average intensity of the diffraction peak of the {111} plane at the tilt angle? Of 47 degrees and the average intensity of the diffraction peak of the {111} plane at the tilt angle? Connect average strength in a straight line. Thus, a longitudinal section of this straight line is obtained.

In the rolled copper foil according to the present embodiment, the average strength of the diffraction peaks of the {111} plane within the range of the graph, that is, within the range of the tilt angle psi of 15 degrees or more and 90 degrees or less, Of the maximum value.

By satisfying the conditions defined by the graphs of the expressions (1) and (2) and the average intensity of the diffraction peaks, the rolled copper foil according to the present embodiment has, after the recrystallization annealing step, And has excellent bending resistance withstanding bending and excellent bending resistance withstanding a small bending radius.

(Properties given to rolled copper foil)

The properties of the rolled copper foil having such a crystal structure as described above will be described below.

As described above, the {022} surface before the recrystallization annealing step is changed to the {002} surface after the recrystallization annealing step and the {002} surface before the recrystallization annealing step remains as it is after the recrystallization annealing step, thereby improving the bending resistance of the rolled copper foil . Further, in the recrystallization annealing step, the {002} plane does not change its crystal orientation but becomes a seed crystal (crystal set), and the {022} plane is changed to the {002} plane to promote growth. Therefore, by satisfying the above-described formula (1) before the recrystallization annealing step, this effect can be sufficiently obtained.

However, the {002} plane need not be present here. That is, the diffraction peak intensity ratio I {002} of the {002} plane may be zero (0). For example, in the case of I {022} + I {002} = 80.0 + 0 = 80.0 and I {022} + I {002} = 60.0 + 20.0 = 80.0 in the equation (1) It can be seen that the rolled copper foils obtained after the recrystallization annealing step have approximately the same crystal structure of {002} planes. Further, the higher the value defined by the left side of the above equation (1) is, the higher the higher the value is, and there is no problem caused by the value of I {022} + I {002} being too high.

On the other hand, {113} plane, {111} plane and {133} plane of the other directions are unnecessary crystal planes which do not contribute to flexing resistance. In particular, as a result of intensive studies conducted by the present inventors, it has been found that the {111} face has a tendency to lower the bending resistance. Therefore, by satisfying the above formula (2), the adverse effect on the bendability due to the {111} plane can be extremely reduced. The lower the value defined by the left side of the formula (2), that is, I {111}, is better as the lower the value of I {111} is.

The inventors of the present invention have also studied bifurcations other than the above-mentioned crystal planes to specify the bifurcation which is advantageous in bending resistance. That is, for example, crystal planes close to the {013} planes or {023} planes or their crystal planes, specifically those having a crystal orientation within about ± 10 degrees of their crystal planes, Respectively. The crystal orientation of these crystal faces does not change even after recrystallization in the recrystallization annealing step. Therefore, with respect to these crystal planes, if the state after the final cold rolling step and before the recrystallization annealing step can be controlled, excellent rolling resistance can be imparted to the rolled copper foil.

However, the {013} plane or the {023} plane was not detected in the X ray diffraction measurement by the 2θ / θ method, even if it was present on the rolled surface of the rolled copper foil. Since copper is a crystal of a face-centered cubic structure, in the X-ray diffraction measurement by the 2? /? Method, h, k and l of the {hkl} plane do not appear as diffraction peaks unless they are both odd or all. If h, k, and l are mixed in the odd and even values as in the {013} plane or the {023} plane, the diffraction peak disappears due to the extinction rule.

There, in the present embodiment, the crystal planes of these are defined by using the X-ray Pole-figure method. In the above, the diffraction peak of the {111} plane at the tilt angle? Of 47 degrees means the presence of the {013} plane parallel to the rolled surface of the rolled copper foil. Further, the state of the {013} plane can be known from the average intensity of the diffraction peaks and the like. The diffraction peak of the {111} plane at the tilt angle? Of 53 degrees means the presence of the {023} plane parallel to the rolled surface of the rolled copper foil. The state of the {023} plane can be found from the average intensity of such diffraction peaks and the like.

When the straight line in the graph of the average intensity of the diffraction peaks satisfies the above-mentioned conditions, the rolled copper foil becomes a rolled copper foil having a sufficiently high occupancy rate of the crystal planes, and excellent bending resistance can be imparted. Whether or not such a straight line satisfies this condition can be determined by comparing the average intensity of the diffraction peak at the tilt angle psi of 47 degrees and the magnitude and the smallness of the average intensity of the diffraction peak at the tilt angle psi at 53 degrees, , The magnitude of the average intensity of these and the average intensity of the maximum value of the graph, and the slope of the straight line connecting the two average intensities.

Further, the inventors of the present invention investigated the point that the rolled copper foil is imparted with the bending resistance by satisfying the above-described condition using the graph of the average intensity of the diffraction peaks as follows. It can be considered that the crystal planes close to the {013} plane or the {023} plane and these crystal planes, that is, the crystal planes having a relatively small difference in crystal orientation with respect to these crystal planes, form a texture when a predetermined amount exists in the rolled copper foil. It is also believed that these crystal planes contribute to the improvement of the bending resistance by forming aggregate structure. The inventors of the present invention have considered that the fact that the longitudinal axis intercept obtained by the above graph is one-fourth of the maximum value of the graph represents a boundary between whether or not these crystal planes form aggregate structure.

(2) Manufacturing method of rolled copper foil

Next, a method of manufacturing a rolled copper foil according to an embodiment of the present invention will be described with reference to Fig. 1 is a flowchart showing the manufacturing process of the rolled copper foil according to the embodiment.

(Preparation process (S10) of ingot)

As shown in FIG. 1, first, an ingot is prepared by casting using pure copper such as oxygen-free copper (OFC) or tough pitch copper as a raw material. The ingot is formed in a plate shape having a predetermined thickness and a predetermined width, for example. Pure copper such as oxygen-free copper or toughpitch copper which is a raw material may be made of a rare copper alloy to which predetermined additives are added to adjust various characteristics of the rolled copper foil.

Various properties that can be adjusted by additives include, for example, heat resistance. As described above, in the rolled copper foil for FPC, the recrystallization annealing step for obtaining a high abrasion resistance is performed by, for example, a step of joining with a substrate of an FPC. The heating temperature at the time of bonding is set in conjunction with the curing temperature (curing temperature) of the substrate made of, for example, resin of FPC, the curing temperature of the adhesive to be used, and the like. In order to adjust the softening temperature of the rolled copper foil to the set heating temperature, an additive capable of adjusting the heat resistance of the rolled copper foil may be added.

The ingot to which the additive is not added and the ingot to which the additive is added are exemplified in Table 1 below as the ingot used in the present embodiment.

[Table 1]

Examples of the additive for increasing or decreasing heat resistance include boron (B), niobium (Nb), titanium (Ti), nickel (Ni) ), Zirconium (Zr), vanadium (V), manganese (Mn), hafnium (Hf), tantalum (Ta) and calcium (Ca). Alternatively, there is an example in which Ag is added as the first additive element, and one or a plurality of elements of these representative elements as the second additive element are added. In addition, it is possible to use a metal such as Cr, Zn, Ga, Ge, As, Cd, In, Sn, Au) may be added in a small amount.

Further, the composition of the ingot is maintained substantially in the rolled copper foil after the final cold rolling step (S40) described later. When the additive is added to the ingot, the ingot and the rolled copper foil have substantially the same additive concentration.

The temperature condition in the annealing step (S32) to be described later is appropriately changed in accordance with the heat resistance by the copper material and the additive. However, such changes in the copper material and the additive, and accordingly the temperature condition of the annealing step (S32) have little effect on the effect of the present embodiment.

(Hot rolling step (S20))

Next, the prepared ingot is subjected to hot rolling to obtain a plate having a thickness thinner than a predetermined thickness after casting.

(Repeating step (S30))

Subsequently, the cold rolling step (S31) and the annealing step (S32) are repeated a predetermined number of times (S30). That is, annealing is applied to a plate material subjected to work hardening by cold rolling to anneal the plate material to alleviate work hardening. By repeating this for a predetermined number of times, copper (copper cloth) called " raw cloth " is obtained. When an additive or the like for adjusting the heat resistance is added to the copper material, the temperature condition of the annealing treatment is appropriately changed in accordance with the heat resistance of the copper material.

The annealing step (S32) during the repetition step (S30) is called "intermediate annealing step". The annealing step (S32) performed immediately before the final cold rolling step (S40), which will be described later, is referred to as a "final annealing step" or a "green sheet annealing step". In the green body annealing step, copper (raw paper) is subjected to a green body annealing treatment to obtain an annealed green body. Also in the green body annealing step, the temperature condition is appropriately changed in accordance with the heat resistance of the copper material. At this time, it is preferable that the green body annealing step be performed under a temperature condition capable of sufficiently alleviating the processing distortion (processing distortion) caused by each of the above-described steps, for example, a temperature condition substantially equivalent to a complete annealing treatment.

(Final cold rolling step (S40))

Then, a final cold rolling step (S40) is carried out. The final cold rolling is also referred to as finish cold rolling, and cold rolling, which is to be finished, is carried out on the annealed sheet several times. At this time, the total working degree is set to 90% or more, more preferably 94% or more, so as to obtain a rolled copper foil having a high abrasion resistance. As a result, after the recrystallization annealing step, the rolled copper foil is more likely to have better bending resistance (bending resistance).

In addition, it is preferable to gradually reduce the processing rate per one pass (one pass) as the annealing sheet becomes thinner each time cold rolling is repeated several times. Here, the degree of processing per pass is represented by TBn as the thickness of the object before rolling on the n-th pass and TAn as the thickness of the object after rolling according to the example of the total degree of processing, %) = [(TBn-TAn) / TBn] X100.

By changing the degree of processing per pass as described above, the diffraction peak intensity ratio of each crystal plane of the rolled copper foil can be controlled.

In the rolling process, the object to be processed such as the annealed raw paper is drawn into a gap between one rolls facing each other, for example, and pulled out to the opposite side, thereby reducing the thickness. The speed of the object to be processed is slower than the speed of rotation of the roll on the inlet side before being drawn into the roll and faster than the speed of rotation of the roll on the exit side after being drawn out of the roll. Therefore, the object to be processed is subjected to compressive stress at the entrance side and tensile stress at the exit side. In order to process the object to be processed thinly, compressive stress> tensile stress must be used. It is possible to adjust the ratio of the respective stress components (compression component and tensile component) on the premise that the compressive stress> tensile stress is adjusted by adjusting the degree of processing per pass.

In the final cold rolling step (S40), it is also possible to adjust the ratio of the stress component (compression component to tensile component) from the viewpoint of control of positional movement of the neutral point described below. That is, as described above, the speed of the object to be processed, in which the magnitude relationship between the entrance side and the exit side is reversed with respect to the rotation speed of the roll, becomes equal to the rotation speed of the roll at a position somewhere between the entrance side and the exit side. A position at which the speed of the two is the same is called a neutral point, and a pressure applied to an object to be processed at the neutral point is the maximum.

The position of the neutral point is determined based on the front tension, the back tension, the rolling speed (the rotational speed of the roll), the roll diameter, the surface roughness of the roll, the degree of processing, (Rolling load) or the like can be controlled. That is, the ratio of the compressive stress and the tensile stress can be adjusted by controlling the position of the neutral point.

The balance of the diffraction peak intensities of each crystal plane is mainly determined by the stress balance between the compressive stress and the tensile stress in the final cold rolling step.

Concretely, during the rolling process such as the final cold rolling step (S40), the copper crystals in the copper material rotate due to the stress during the rolling process, and change to {022} in several paths. The larger the compressive stress, the easier it is to pass through the {013} plane or the {023} plane, and the larger the tensile stress becomes, the more easily the {111} plane is passed. And each is changed to the {022} plane. Crystals that have not reached the {022} plane or crystals that have reached the {022} plane but have been rotated to the {111} plane by the tensile stress become diagonal.

By thus changing the stress balance between the compressive stress and the tensile stress, it is possible to adjust the balance of the diffraction peak intensity at the crystal face of the diagonal direction. The balance of the diffraction peak intensities of these crystal planes greatly affects the bending resistance and bending resistance of the rolled copper foil as described above.

The rolled copper foil satisfying the above equations (1) and (2) can be obtained by carrying out the final cold rolling step (S40) while controlling the degree of processing degree in each path and controlling the position of the neutral point. In addition, the longitudinal axis section of the graph of the average intensity of the diffraction peaks of the {111} plane is one fourth or more of the maximum value of the graph. Therefore, after the recrystallization annealing step, a rolled copper foil having high bending resistance against repeated bending and excellent bending resistance against small bending radius is obtained.

(Surface treatment step (S50))

The copper subjected to the above-described steps is subjected to predetermined surface treatment. Thus, the rolled copper foil of the present embodiment is produced.

(3) Manufacturing Method of Flexible Printed Circuit Board

Next, a method of manufacturing a flexible printed wiring board (FPC) using a rolled copper foil according to an embodiment of the present invention will be described.

(Recrystallization annealing step (CCL step))

First, the rolled copper foil according to the present embodiment is cut to a predetermined size and bonded to a base material of an FPC made of resin such as polyimide to form a CCL (Copper Clad Laminate). At this time, either of the method for forming the three-layered CCL to be bonded through the adhesive and the method for forming the two-layered CCL to be bonded directly without passing through the adhesive may be used. In the case of using an adhesive, the adhesive is hardened (cured) by a heat treatment so that the rolled copper foil and the substrate are closely contacted and integrated. When the adhesive is not used, the rolled copper foil and the substrate are brought into direct contact with each other by heating and pressing. The heating temperature and time can be appropriately selected in accordance with the adhesive or the curing temperature of the substrate, and can be set to, for example, from 1 minute to 120 minutes at a temperature of from 150 degrees to 300 degrees.

As described above, the heat resistance of the rolled copper foil is adjusted to the heating temperature at this time. Therefore, the rolled copper foil is softened and recrystallized by heating in the CCL process. That is, the CCL process for bonding the rolled copper foil to the substrate also serves as a recrystallization annealing process for the rolled copper foil. The rolled copper foil is subjected to a recrystallization annealing step to obtain a rolled copper foil having a recrystallized structure.

That is, before the recrystallization annealing process, most of the {022} planes that were kitchen and the {002} planes that became the planes became the {002} planes co-crystallized with the recrystallized structure. Thus, high flex resistance is obtained.

Further, the other side, after recrystallization, is hardly changed while maintaining the state after the final cold rolling step, and is tempered into a recrystallized structure. However, the effect of work hardening is removed from the crystal planes of these directions by the recrystallized state, and the action of the crystal planes of these directions is expressed in a form close to the maximum.

For example, the effect of lowering the bending resistance due to the {111} face is exhibited. However, the rolled copper foil according to the present embodiment satisfies the above formula (2) and its action is suppressed when the occupancy rate of the {111} face is low. In addition, the effect of improving the bending resistance of the {013} plane or {023} plane is exhibited. At this time, the {013} plane and the {023} plane exhibit a remarkable effect when the occupation rate is sufficiently high by the conditions obtained from the above graph.

In addition, each crystal plane of the cubic phase is hardly changed before and after the recrystallization annealing process. Therefore, in order to obtain the bending resistance and the bending resistance, the bending of the rolled copper foil after the final cold rolling step and before the recrystallization annealing step may be controlled so as to satisfy the above relational expression or condition.

Further, in the process up to the step of joining the rolled copper foil to the base material by the CCL process as a recrystallization annealing process, the rolled copper foil can be handled in a state of work hardening after the cold rolling process, Deformation such as elongation, wrinkling, bending, etc. of the sheet can be made less likely to occur.

(Surface processing step)

Next, the rolled copper foil bonded to the substrate is subjected to a surface processing step. In the surface processing step, a surface of the rolled copper foil is subjected to a wiring forming step of forming a copper wiring or the like using a method such as etching and a surface treatment such as a plating treatment in order to improve the connection reliability between the copper wiring and the other electronic member A protective film forming step of forming a protective film such as solder resist or the like so as to cover a part of the copper wiring is carried out in order to protect the copper wiring and the like.

Thus, an FPC using the rolled copper foil according to the present embodiment is manufactured.

≪ Another embodiment of the present invention >

The embodiments of the present invention have been described above in detail. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, in the above embodiment, Ag is mainly used as an additive for adjusting the heat resistance of the rolled copper foil. However, the additive is not limited to Ag or the representative examples described above. The various properties adjustable by the additive are not limited to heat resistance, and the additive may be appropriately selected depending on various properties requiring adjustment.

In the above embodiment, the CCL process in the FPC production process also serves as a recrystallization annealing process for the rolled copper foil. However, the recrystallization annealing process may be a process different from the CCL process.

Further, in the above embodiment, the rolled copper foil is used for the FPC application, but the use of the rolled copper foil is not limited to this, and can be used for applications requiring bending resistance and bending resistance. The thickness of the rolled copper foil may be, for example, 10 μm or less, ultra-thin or 20 μm or more depending on various uses including FPC applications.

Further, in the above embodiment, excellent bending resistance is obtained with the total working degree in the final cold rolling step (S40) being not less than 90%, etc. However, a method of obtaining the bending resistance by adjusting the crystal face of the bimanite Can be used independently. That is, in the case where the bending resistance is particularly important and a certain degree of bending resistance can be obtained, the total working degree in the final cold rolling step is set to less than 90%, for example 85%, 75%, 65% .

Further, in the above embodiment, in the detection of the {013} plane and the {023} plane, the measurement is performed by the reflection method in particular in the X-ray Pole-figure method, but it may be measured by the transmission method . In addition to the X-ray Pole-figure method, an Inverse Pole-figure method or another method may be used.

In addition, in order to obtain the effect of the present invention, it is not necessarily that all the above-described steps are necessary. The various conditions of the above-described embodiments and later-described embodiments are exemplary only, and can be appropriately changed.

[Example]

Next, examples of the present invention will be described together with comparative examples.

(1) Rolled copper foil using oxygen free copper

First, rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 using oxygen-free copper were prepared as follows, and various evaluations were made for each.

(Production of rolled copper foil)

Rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 were produced in the same procedure and in the same manner as in the above embodiment, using oxygen-free copper with Ag added at a target concentration of 200 ppm. However, for the comparative examples 1 to 5, a process of deviating from the configuration is included.

Specifically, an ingot having a thickness of 150 mm and a width of 500 mm obtained by dissolving a predetermined amount of Ag in oxygen free copper was prepared. The analytical values of the Ag concentration in the ingot are shown in Table 2 below by analysis by high frequency inductively coupled plasma (ICP: Inductively Coupled Plasma) emission spectrometry.

[Table 2]

As shown in Table 2, for the target concentration of 200 ppm, the analytical value is 180 ppm to 220 ppm, and all of them are suppressed to within a deviation of about 200 ppm ± 20 ppm (10%). Ag is originally contained in an amount of several ppm to several tens of ppm as an inevitable impurity in anoxic copper which is a main raw material, and in addition, there is a possibility that Ag is contained within about 20 ppm Unevenness is common in the metal materials field.

Next, a plate material having a thickness of 8 mm was obtained in the hot rolling step in the same order and in the same manner as in the above embodiment, and the cold annealing step and the intermediate annealing step in which the cold rolling step and the annealing step were performed at a temperature of 750 to 850 degrees for about 2 minutes were repeatedly carried out, Copper (raw paper) having a thickness of 0.6 mm was produced. And then kept at a temperature of about 750 DEG C for about 2 minutes to obtain an annealed green sheet.

Here, the temperature conditions and the like of each annealing step are adjusted to the heat resistance of the oxygen-free copper material containing 180 ppm to 220 ppm of Ag. The reason why different temperature conditions are used in the respective annealing processes for a copper material of the same composition is that the heat resistance changes depending on the thickness of the copper material, and the temperature can be lowered when the copper material is thin.

Finally, the final cold rolling step was performed in the same procedure and the same manner as in the above embodiment. Conditions in the final cold rolling step are shown in Table 3 below.

[Table 3]

As shown in Table 3, as the thickness of the plate became gradually thinner from the top to the bottom of each table, the conditions were changed as in the case of the right and the final cold rolling was performed. That is, the processing and neutral position of one pass of the cold rolling at a thickness of 600 탆 or less were changed. The position (mm) of the neutral point shown in the right column is the length from the outlet side end of the contact surface of the roll to the object to be annealed to the neutral point.

In order to obtain excellent bending resistance, conditions were set so that the total working degree in the final cold rolling step in Examples 1 to 5 and Comparative Examples 1 to 5 was 94% or more. Concretely, the total processing degree of the examples 1 to 5 and the comparative examples 1 to 5 was set to 98%. Thus, the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 having a thickness of 12 占 퐉 were produced.

Next, each rolled copper foil produced as described above was evaluated as follows.

(X-ray diffraction measurement by the 2? /? Method)

First, the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 were subjected to X-ray diffraction measurement by the 2? /? Method. Details of the measurement method will be described below with reference to Fig. 2 is a diagram showing an outline of a method of measuring X-ray diffraction in the examples and comparative examples of the present invention.

As shown in FIG. 2, the sample piece 50 of the rolled copper foil of Examples 1 to 5 and Comparative Examples 1 to 5 was rotated about three scanning axes of the? Axis,? Axis, and? As possible. These three scanning axes are generally referred to as a sample axis, a tilting axis, and an in-plane rotation axis, respectively. The measurement of the X-ray diffraction pattern in the present embodiment is based on the X-ray (Cu K?) Generated when the electrons of the L-orbital (L shell orbits) transit to the K-angular orbit by X- Line) shall be used.

In the X-ray diffraction measurement using the 2? /? Method, the sample piece 50 and the detector not shown in the figure are scanned with respect to the incident X-ray on the? -Axis (rotated about the? -Axis). At this time, the scanning angle of the sample piece 50 is referred to as an angle?, And the scanning angle of the detector is referred to as an angle 2 ?. Thus, as described above, the incident X-ray is incident at the angle?, And the diffracted X-ray diffracted at the angle 2? Is detected.

In this example and the comparative example, these measurements were made under the conditions shown in the following Table 4 by using an X-ray diffraction apparatus (type: Ultima IV) of Rikaku Co., 3 (a) and 3 (b) show X-ray diffraction charts of Examples 1 and 2 and FIG. 3 (c) show X-ray diffraction charts of Comparative Example 1, respectively.

[Table 4]

Next, the diffraction peak intensities of the {022} plane, the {002} plane, the {113} plane, the {111} plane and the {133} plane of the copper crystals measured by the 2θ / , And the diffraction peak intensity ratio of each crystal plane was determined. The value of the above expression (1), that is, the value of (I {022} + I {002}) was obtained. Table 5 below shows the diffraction peak intensity ratios I {022}, I {002}, I {113}, and I {111} of the crystal faces obtained as described above for the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5, I {111} (equation (2)), I {133} and the value of equation (1).

[Table 5]

As described above, in the present embodiment and the comparative example, the processing degree and the position of the neutral point per one pass in the final cold rolling step are changed. As a result, the ratio of the compressive component applied to the object to the stress component of the tensile component changes during cold rolling. As a result, the ratio of each crystal plane changes, and the diffraction peak intensity ratio of each crystal plane shown in Table 5 and the value related to the formula (1) also change.

As shown in Table 5, in the combination of the conditions of Examples 1 to 5, the respective values of the formulas (1) and (2) were within the above-mentioned predetermined ranges.

On the other hand, in the combination of the respective conditions of Comparative Examples 1 to 5, one or both of the values of the formulas (1) and (2) in some rolled copper foils was out of the predetermined range. In Table 5, values out of the predetermined range are shown in bold underlined.

(Measurement by X-ray Pole-figure method)

Next, the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 were measured by X-ray Pole-figure method. Such a measurement method includes a reflection method in which a tilt angle (ψ) described later is set in a range of 15 degrees to 90 degrees, and a transmission method in a range of 0 degrees to 15 degrees. In this embodiment, the reflection method is used. Details of the measurement method will be described below with reference to Fig.

As shown in Fig. 2, in the measurement using the X-ray Pole-figure method, the sample pieces 50 of the rolled copper foil are arranged like the X-ray diffraction measurement using the 2? /? Method.

In the X-ray Pole-figure method, the measurement is performed using the tilt angle (ψ) defined below. That is, the tilt angle? In the direction perpendicular to the sample piece 50 (? Axis direction) is defined as 90 degrees. Also, the angle formed between {hkl} plane and {hkl} plane, which is a geometrically corresponding crystal face, is called a polygonal plane {hkl}. At this time, the tilt angle? Is defined as 90 -? '.

Based on this rule, the sample piece 50 is rotated in the ψ-axis direction (rotated around the ψ axis), and the tilt angle ψ is changed within a range of 15 degrees or more and 90 degrees or less. That is, the sample piece 50 is tilted at a tilt angle? Within the above range. The diffraction X-ray is detected in the same manner as the 2? /? Method in a plurality of tilt angles? While changing the tilt angle?. That is, when the tilt angle psi is 90 degrees, the measurement is basically the same as the 2? /? Method.

Further, in the measurement at each tilt angle psi, the scanning angle of the detector is fixed to the angle 2 &thetas; and the sample piece 50 is scanned with respect to the 2 [theta] value of the {h'k'l ' (rotation about the? axis), and the in-plane rotation angle? is changed within the range of 0 degrees to 360 degrees. That is, the sample piece 50 is rotated by the in-plane rotation angle? Within the above range. The average intensity of diffraction peaks in the in-plane rotation angle? Of 0 degree or more and 360 degrees or less with respect to the diffraction peaks of {h'k'l '} surfaces thus measured is obtained for each tilt angle .

At this time, the {h'k'l '} surface detected at the predetermined tilt angle psi corresponds geometrically to the {hkl} plane parallel to the rolled surface of the rolled copper foil. In the present embodiment, {hkl} planes to be considered are {013} planes and {023} planes. The geometric relationship with the {001} plane parallel to the rolled surface of the rolled copper foil is the {111} plane detected at the tilt angle psi of 47 degrees. Also, the geometrical relationship with the {023} plane parallel to the rolled surface of the rolled copper foil is the {111} plane detected at the tilt angle psi of 53 degrees.

Therefore, from the graph of the average intensity of the diffraction peaks of the {111} plane obtained by using the X-ray Pole-figure method as described above, it is possible to judge whether or not the rolled copper foil of this embodiment has a predetermined crystal structure have.

In the present example and the comparative example, the X-ray diffraction apparatus (type: Ultima IV) of Rikaku Co., Ltd. was used and the measurement was carried out under the conditions shown in Table 6 below. 4 to 8 are graphs showing the average intensity of diffraction peaks of {111} planes related to Examples 1 to 5. 9 to 13 show graphs showing the average intensity of diffraction peaks of the {111} planes of Comparative Examples 1 to 5.

[Table 6]

The abscissa of the graphs in FIGS. 4 to 13 is the tilt angle? (Degrees), and the ordinate is the diffraction peak intensity (arbitrary unit). In the graph, the average intensity obtained by the measurement using the X-ray Pole-figure method is shown. The graph also shows the maximum value and the value of the average intensity of the diffraction peaks of the {111} plane within the range of the graph. The graph also shows a straight line connecting the average intensity of the diffraction peaks of the {111} plane at a tilt angle (ψ) of 47 degrees and 53 degrees, respectively, and a longitudinal axis section thereof.

As shown in Figs. 4 to 13, in the results of Examples 1 to 5, all the longitudinal axis segments exceeded one-fourth of the maximum value of the graph, and the above conditions were satisfied. On the other hand, in the results of Comparative Examples 1 to 5, all of the longitudinal axis segments were less than one quarter of the maximum value of the graph, and the above conditions were not satisfied.

(Bending fatigue life test)

Next, in order to investigate the bending resistance of each rolled copper foil, a bending fatigue life test (bending fatigue life test) in which the number of repeated bending times (number of bending) until each rolled copper foil was broken was measured. These tests were conducted in accordance with the IPC (American Printed Circuit Industry Association) standard using an FPC high-speed bending tester (type: SEK-31B2S) manufactured by Shin-Etsu Engineering Co., Fig. 14 is a schematic diagram of a general sliding bending test apparatus 10 including an FPC high-speed bending tester manufactured by Shin-Etsu Engineering Co., Ltd. Fig.

First, the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 were cut to a width of 12.5 mm and a length of 220 mm, and a sample piece 50 having a thickness of 12 탆 was subjected to the above recrystallization annealing process at 300 degrees for 60 minutes Recrystallization annealing was performed. These conditions follow an example of the amount of heat actually received by the rolled copper foil when the flexible printed wiring board is closely contacted with the substrate in the CCL process.

Next, as shown in Fig. 14, the sample piece 50 of the rolled copper foil was fixed to a sample fixing plate (sample fixing plate) 11 of a sliding bending test apparatus 10 with a screw 12. Subsequently, the sample piece 50 is brought into contact with and attached to the vibration transmission portion 13, and the vibration transmission portion 13 is oscillated in the up-and-down direction by the oscillation drive body 14, And the flex fatigue life test was carried out. The bending fatigue life was measured under the conditions that the bending radius 10r was 1.5 mm, the stroke 10s was 10 mm, and the number of amplitudes was 25 Hz. Under these conditions, five sample pieces 50 cut out from each rolled copper foil were measured, and the average value of the number of times of bending until breakage occurred was compared. The results are shown in Table 7 below.

[Table 7]

As shown in Table 7, in Examples 1 to 5 and Comparative Examples 3 and 5, all of the above-mentioned expressions (1) were satisfied, so that a high bending resistance with a bending frequency of 2,000,000 times or more was obtained. On the other hand, in Comparative Examples 1, 2 and 4 which do not satisfy the above-mentioned formula (1), all of the bending times were less than 2,000,000 times.

It should be noted that Comparative Examples 1, 2, and 4 originally have comparatively high level of bending resistance. This is because, for example, in the above-described Patent Document 3 and the like, the final cold rolling step is carried out in which the total working degree is 94% or more, specifically, the total working degree is 98%. In Examples 1 to 5, flexural resistance can be further improved by satisfying the above formula (1).

(Evaluation of bending resistance)

Then, the bending resistance of each rolled copper foil was examined. The general test standard for bending resistance does not standardize the 180 degree bending required for FPC applications, for example. Therefore, a bending test was performed to measure the number of bending times until breakage occurred in each rolled copper foil by the method shown in Fig.

That is, first, the rolled copper foils of Examples 1 to 5 and Comparative Examples 1 to 5 were subjected to recrystallization annealing at 300 占 폚 for 60 minutes in the sample piece 50 cut into 15 mm in width and 100 mm in length in the rolling direction. Next, as shown in FIG. 15, the sample piece 50 was bent 180 degrees so as to surround the spacer 20 having a thickness of 0.25 mm. In this state, the bent portion was observed with a metallurgical microscope to check whether or not breakage occurred . If there is no break, the rolled copper foil returns from the bent state to the original unfolded state. The cycle was repeated until breakage occurred while observing the bending portion every five cycles of each sample piece 50 cut out from each rolled copper foil by one cycle, and the number of bending was measured. The results are shown in Table 8 below.

[Table 8]

As shown in Table 8, in any of Examples 1 to 5, which satisfies both the above-mentioned condition (2) and the conditions obtained from the above-mentioned graphs, the number of bending times was 100 or more, and excellent bending resistance was obtained.

On the other hand, in all comparative examples including Comparative Examples 3 and 5 which exhibited excellent flexing resistance, except for Comparative Example 4, neither the formula (2) nor the above conditions were satisfied and the folding number was less than 100 times, Sufficient bending resistance was not obtained. However, for Comparative Example 4 satisfying only Formula (2), the number of bending times was 61, and slight improvement was recognized as compared with other Comparative Examples.

(2) Rolled copper foil using tough pitch copper

Next, a rolled copper foil for Example 6 and Comparative Examples 6 and 7 having a thickness of 12 탆 was prepared using tough pitch copper doped with Ag at a target concentration of 200 ppm and by the same procedure and method as those of the above examples. However, for Comparative Examples 6 and 7, processing for deviating from the configuration is included.

The Ag concentrations in the ingot of Example 6 and Comparative Examples 6 and 7 were 190 ppm, 204 ppm and 199 ppm, respectively, as obtained by IPC emission spectrometry. All are within ± 10% and are common in the field of metal materials. In addition, in accordance with the heat resistance of the tough pitch copper material containing Ag at such a concentration, conditions different from the above conditions were used in the intermediate annealing step and the green body annealing step. Specifically, in the intermediate annealing step, the temperature was maintained at about 650 ° C. to about 750 ° C. for about 2 minutes to about 4 minutes, and in the green body annealing step, the temperature was maintained at about 700 ° C. for about 2 minutes. The conditions of Table 3 above were also applied to the final cold rolling step for this example and the comparative example.

The rolled copper foil of Example 6 and Comparative Examples 6 and 7 thus prepared was subjected to X-ray diffraction measurement by the 2? /? Method and X-ray Pole-figure method using the same method and procedure as those of the above- And the above equations (1) and (2) were obtained, and a graph was prepared as described above. Figs. 16 to 18 show graphs relating to Example 6 and Comparative Examples 6 and 7 prepared by using the X-ray Pole-Figure method, respectively. Table 9 below shows the results of X-ray diffraction measurement by the 2? /? Method.

[Table 9]

As shown in Table 9 and Figs. 16 to 18, regarding the rolled copper foil according to Example 6, Satisfies both the expressions (1) and (2) and satisfies the conditions defined from the graph of the average intensity. On the other hand, the rolled copper foil of Comparative Example 6 satisfies the formula (1), but deviates from the predetermined range of the formula (2) and deviates from the conditions defined by the graph. For the rolled copper foil of Comparative Example 7, the formula (2) was within a predetermined range, but deviated from the conditions defined by the formula (1) and the graph. In Table 9, values out of the predetermined range are shown in bold underlined letters.

The rolling copper foil of Example 6 and Comparative Examples 6 and 7 was subjected to a flex fatigue life test in the same manner and in the same manner as in the above Examples. As a result, with respect to Example 6 and Comparative Example 6 satisfying the above-mentioned formula (1), the flexing resistance was as high as 2, 131,000 and 2,098,000 times, respectively, all at two million or more times. On the other hand, in Comparative Example 7 in which the above-mentioned formula (1) was not satisfied, the number of times of bending was 1,688,000 times, which was less than two million times.

The rolled copper foil of Example 6 and Comparative Examples 6 and 7 was subjected to a bending test in the same manner and in the same manner as in the above Examples. As a result, it was found that the number of bending times in Example 6 was good at 98, while in Comparative Example 6, 39 times and in Comparative Example 7 satisfying Formula (2), slight improvement was recognized. However, The result was a fall.

The above results are shown in Table 10 below. In Table 10, values out of the predetermined range are expressed in bold letters underlined.

[Table 10]

From the above, it has been found that, when the respective crystal planes are within a predetermined range, good rolling resistance can be obtained even for a rolled copper foil containing tough pitch copper as a main raw material, and the bending resistance can be improved.

(3) Rolled copper foil using other additives

Next, by using the same procedure and the same procedure as in the above example, except that the target concentration was 120 ppm and the concentration of Ag and the target concentration were 40 ppm and oxygen (Ti) was added as an additive, Rolled copper foils of Comparative Examples 8 and 9 were produced. However, for the comparative examples 8 and 9, a process of deviating from the configuration is included.

Ag concentrations in the ingot of Example 7 and Comparative Examples 8 and 9 were 117 ppm, 121 ppm and 120 ppm, respectively, as obtained by IPC emission spectrometry. The Ti concentrations were 39 ppm, 38 ppm and 39 ppm, respectively. All are within ± 10% and are common in the field of metal materials.

In addition, in accordance with the heat resistance of the oxygen-free copper material containing Ag and Ti at these concentrations, conditions different from the above conditions were used in the intermediate annealing step and the green sheet annealing step. Specifically, in the intermediate annealing step, the temperature was maintained at about 650 ° C. to 750 ° C. for about 1 minute to 3 minutes, and at the temperature of about 700 ° C. for about 1 minute in the green body annealing step. Also in this embodiment and the comparative example, the conditions of Table 3 were applied in the final cold rolling step.

The rolled copper foil of Example 7 and Comparative Examples 8 and 9 thus prepared was subjected to X-ray diffraction measurement by the 2? /? Method and X-ray Pole-figure method using the same method and procedure as those of the above- And the above equations (1) and (2) were obtained, and a graph was prepared as described above. Table 11 below shows the results of X-ray diffraction measurement by the 2? /? Method.

[Table 11]

As shown in Table 11, for the rolled copper foil of Example 7, the relationship of the diffraction peak intensities of the respective crystal planes satisfies all of the formulas (1) and (2) It was also meeting the prescribed conditions. On the other hand, with respect to the rolled copper foil of Comparative Example 8, all of the expressions (1) and (2) were out of the range and were not shown in the drawings, but were deviated from the conditions specified from the graph. For the rolled copper foil of Comparative Example 9, the expressions (1) and (2) were within a predetermined range, but deviated from the conditions specified from the graphs not shown in the drawings. In Table 11, values out of the predetermined range are shown in bold underlined.

The rolled copper foil of Example 7 and Comparative Examples 8 and 9 was subjected to the flex fatigue life test in the same manner and in the same manner as in the above Examples. As a result, with respect to Example 7 and Comparative Example 9 satisfying the above formula (1), the flexing resistance was as high as 2,000,000 times or more at 2,142,000 times and 2,122,000 times, respectively. On the other hand, in Comparative Example 8 in which both of the above-mentioned equations (1) and (2) were not satisfied, the number of flexing was 1,701,000 times, which was less than 2,000,000 times.

The rolled copper foil of Example 7 and Comparative Examples 8 and 9 was subjected to a bending test in the same manner and in the same manner as in the above Examples. As a result, although the number of bending times was good in Example 7, the number of bending times was good in 101 times, while in Comparative Example 8, 36 times and in Comparative Example 9 in which the Formula (2) was satisfied, slight improvement was recognized. The result was a fall.

The above results are shown in Table 12 below. In Table 12, values out of the above-mentioned predetermined range are indicated in bold underlined letters.

[Table 12]

From the above, it can be seen that when the crystal faces are within a predetermined range, the rolling resistance of the rolled copper foil to which other additive materials such as Ag and Ti are added is also excellent in bending resistance and bending resistance.

≪ Discussion by the present inventors &

The discussion by the inventors of the present invention on the structure of the control of the crystal face of the bipolar plate in the production process of the rolled copper foil will be described below.

(1) About crystal rotation

As described above, during the rolling process such as the final cold rolling process, the copper material is subjected to a tensile stress that is weaker than compressive stress and compressive stress. Copper crystals in the rolled copper material cause a rotation in the plane of {022} due to the stress during the rolling process, and the orientation of the crystal planes parallel to the rolled surface mainly forms a {022} do. At this time, as described above, the path of rotation toward the {022} plane changes due to the ratio of compressive stress to tensile stress. This will be described with reference to FIG.

19 is an inverse pole figure of a pure copper type metal cited from the following technical reference 1, wherein (a) is an inverse pole figure showing a crystal rotation direction by tensile deformation, (b) Direction. In the reverse poles, the {002} plane is denoted as {001} plane and the {022} plane denoted as {011} plane. That is, the {002} plane is represented by the {001} plane which is the minimum value of the plane parallel to the {002} plane, and the {022} plane is represented by the {011} plane which is the minimum value of the plane parallel to the {022} plane.

2.52 (a), (c) of p96, Mar. 1, 1984, Mar. 20, 1984, Technical Document 1: Edited by Shinichi Nagashima,

As shown in Fig. 19, the copper crystals in the copper material rotate toward the {111} plane only by the deformation caused by the tensile stress and rotate toward the {011} plane only by the deformation due to the compressive stress. In the rolling process, the direction of crystal rotation is not so simple because the compression component and the tensile component are deformed together. However, since the compressive component predominates over the tensile component and is rolled, the {111} surface tends to rotate partly due to the ratio of the compressive component to the tensile component while causing crystal rotation toward the {011} plane. At this time, since the compression component is predominant, a crystal rotation in which the crystal that has started to rotate on the {111} plane is returned to the {011} plane also occurs. Conversely, on the other hand, a crystal rotating toward the {011} plane or a crystal reaching the {011} plane may be rotated toward the {133} plane or the {111} plane by the tensile component.

When crystal rotation occurs in such a way that the compression component and the tensile component maintain the relationship between the compression component and the tensile component, the crystal surface on the kitchen finally becomes a {011} plane, and a mixture of the compression component and the tensile component It is considered that the crystal plane of the cubic phase is {001} plane, {113} plane, {111} plane, and {133} plane.

The crystal orientations of the reverse poles shown in Fig. 20 are general, but the crystal planes of {013} plane, {023} plane and those of crystal planes having a relatively small difference in orientation from those crystal planes are shown in the figure. As shown in Fig. 20, in the crystal rotation by the compressive stress, it rotates to the {011} plane ({022} plane) via the {013} plane or the {023} plane or the like.

In the rolling process, as described above, unless both the compressive stress and the tensile stress less than the compressive stress are added to the rolled copper material, the copper material can not be rolled while maintaining the shape of the copper material. In other words, with compression stress alone, it becomes a radially expanded shape as in a simple press working. Compressive stress> The crystal which has been rotated toward the {111} plane by the influence of the tensile stress or the orientation in which the rotation has not reached up to the {022} plane assumes that the tensile stress is referred to. The {111} planes that decrease the bending strength are formed by tensile stress, and the {013} planes and {023} planes that improve the bending resistance are formed by compressive stress.

Therefore, in order to suppress the occupancy rate of the {111} plane on the rolled surface of the rolled copper foil as much as possible and to increase the occupancy of the {013} plane or the {023} plane as much as possible, Rolling becomes important.

(2) Control in the final cold rolling process

The compression component and the tensile component can be controlled by changing the rolling conditions per pass at the time of rolling, for example, as in the final cold rolling step (S40) of the above embodiment. That is, as attempted in the foregoing embodiments and examples, for example, it is possible to pay attention to a change in the degree of processing per one pass.

Further, in the above-described embodiment and examples, the position control of the neutral point is performed in addition to the processing per pass in the final cold rolling step. That is, in the adjustment of the control parameters of the compression component and the tension component, for example, the positional change of the neutral point may be considered.

The control factors such as the degree of processing and the position of the neutral point are related to the constitution of the rolling mill and depend heavily on the specification of the rolling mill. More specifically, a method of adding a compressive stress to a copper material due to differences in the roll configuration such as the number of rolls, the total number of rolls, the combination of rolls, the diameter and the material of each roll, and the surface condition (surface roughness) Friction coefficient and the like. If the rolling mills are different, the absolute values of the respective control factors related to the conditions in the above-described embodiments also can be adjusted appropriately for each rolling mill. Also in the same rolling mill, when the surface state of the rolling roll or the material of the rolling roll is different, the absolute value of each control factor becomes different. Therefore, even the same rolling mill can be appropriately adjusted according to each state.

In the above-described embodiments and examples, the position of the neutral point is controlled as a variable control factor of the degree of processing, but control using control factors other than the degree of processing is also possible.

For example, if the degree of processing per pass is made constant and the surface roughness of the rolling roll is changed, the coefficient of friction of the rolled copper material changes, the position of the neutral point changes, and the rolling load also changes. As a result, the balance between the compressive stress and the tensile stress in the rolling process changes, and the rotation direction and rotation path of the copper crystal change.

(3) Other control factors

In the above embodiments and examples, the rotation direction and the rotation path of the copper crystal are controlled by the rolling conditions in the final cold rolling step, but the same control is possible in other steps.

For example, the rolling conditions of the final cold rolling process are made constant, and the conditions of the production process up to just before the final cold rolling process are changed, thereby influencing the final cold rolling process. In addition, Can be changed indirectly. However, as in the above embodiments and examples, when the rolling conditions in the final cold rolling step are changed, the rotation direction and the rotation path can be directly controlled, and the controllability can be further enhanced.

The state of the crystal orientation of the rolled copper foil after the final cold rolling step is not limited to a specific production method. The state of the crystal orientation of the rolled copper foil can be controlled by various methods, and there are various methods thereof.

10 Sliding bending test equipment
11 Sample fixing plate
12 Screw
13 vibration transmission portion
14 oscillation drive body
20 spacers
50 sample piece

Claims (6)

(Final cold rolling step) having a main surface (main surface) and having a plurality of crystal planes (crystal planes) parallel to the main surface, and after the recrystallization annealing step (annealing step) (Rolled copper foil)
Wherein the plurality of crystal planes include {022} plane, {002} plane, {113} plane, {111} plane and {133}
The diffraction peak intensity ratios (diffraction peak intensity ratios) of the respective crystal planes obtained by X-ray diffraction measurement (X-ray diffraction measurement) using the 2? /? Method on the main surface so as to have a total value of 100 were defined as I {022 }, I {002}, I {113}, I {111} and I {133}
I {022} + I {002}? 80.0,
I {111}? 5.0,
The X-ray Pole-figure method is used and, for each of a plurality of tilt angles in a range of 15 degrees or more and 90 degrees or less, an in-plane rotation angle of the main surface is set to a range of 0 degrees to 360 degrees The average intensity of the diffraction peaks of the {111} plane measured by varying was obtained,
When a graph showing the average intensity of the diffraction peaks of the {111} plane was prepared with the tilt angle as the horizontal axis and the diffraction peak intensity as the vertical axis,
A straight longitudinal axis section connecting the average intensity of the diffraction peaks of the {111} planes at the tilt angle of 47 degrees and the average intensity of the diffraction peaks of the {111} planes at the tilt angle of 53 degrees, And a tilt angle of not less than 1/4 of a maximum value of an average intensity of diffraction peaks of the {111} plane within a range of 15 degrees or more and 90 degrees or less.
The method according to claim 1,
Wherein the copper foil is made of oxygen-free copper or tough-pitch copper (TPC).
3. The method according to claim 1 or 2,
Wherein at least one of silver, boron, titanium and tin is added.
3. The method according to claim 1 or 2,
Wherein the thickness is 20 占 퐉 or less.
3. The method according to claim 1 or 2,
And the total working degree in the final cold rolling step is 90% or more.
3. The method according to claim 1 or 2,
Wherein the copper foil is for a flexible printed wiring board.

Images