TW201440915A - Rolled copper foil having a copper-electroplated layer - Google Patents

Abstract

This invention is a rolled copper foil having a copper-electroplated layer which has excellent folding endurance after re-crystallization annealing process. The rolled copper foil having a copper-electroplated layer has a rolled copper foil formed by a final cold rolling step and followed by a re-crystallization annealing process, and one copper-electroplated layer on at least one side of the rolled copper foil. For a plurality of crystal surfaces of the rolled copper foil having a copper-electroplated layer, when the intensity fraction of a diffraction peak obtained by X-ray diffraction according to 2<theta>/<theta> is performed to surface {111}, surface {002}, and surface {022}, and when PR{111}, PR{002}, PR{022}, PM{111}, PM{002}, PM{022} are individually set, the rolled copper foil having a copper-electroplated layer will become one of the following states: it satisfies PM{111} ≥ 15.0, further satisfies PM{111} > (PR{111}+5), PM{002} < (PR{002}-10) or PM{002} > (PR{002}+10), or PM{022} < (PR{022}-10) or PM{022} > (PR{022}+10).

Description

Calendered copper foil with copper plating

The invention relates to a rolled copper foil with a copper plating layer, in particular to a rolled copper foil with a copper plating layer for a flexible printed circuit board

The flexible printed circuit board (FPC: Flexible Printed Circuit) is thin and excellent in flexibility, and thus has high degree of freedom in an actual mounted state of an electronic device or the like. Therefore, the FPC is widely used for hard disk drives (HDD: Hard Disk Drive) and digital multi-purpose optical discs (DVD: Digital) in addition to the moving parts of the folding portion of the foldable mobile phone, the digital camera, and the printer head. Wiring of the moving parts of the disk-related equipment such as Versatile Disk) and CD (Compact Disk). Therefore, for the FPC and the rolled copper foil used as the wiring material, high bending property, that is, excellent bending resistance against repeated bending is required.

The FPC is produced by rolling a rolled copper foil through steps such as hot rolling and cold rolling. In the subsequent manufacturing step of the FPC, the rolled copper foil is bonded by an adhesive or an FPC base film (substrate) directly formed of a resin such as polyimide or the like by heating or the like. The rolled copper foil on the substrate is subjected to surface processing such as etching to form a wiring. The bending resistance of the rolled copper foil in the state after annealing by recrystallization softening is remarkably improved as compared with the hard state after cold rolling in which rolling and solidification are performed. Therefore, for example, in the production step of the FPC described above, the cured rolled copper foil after cold rolling is used, and the rolled copper foil is cut off while being deformed such as elongation or wrinkles, and is superposed on the substrate. Then, by performing a step of laminating the rolled copper foil and the substrate, and heating, the recrystallization annealing of the rolled copper foil is performed to improve the bending resistance.

On the premise of the above-described manufacturing steps of the FPC, various studies have been made on a rolled copper foil excellent in bending resistance and a method for producing the same. According to the results, it has been reported that the more the {002} plane ({200} plane) in which the surface of the rolled copper foil is cubically aligned, the higher the bending resistance.

For example, in Patent Document 1, annealing before final cold rolling is performed under the condition that the average particle diameter of the recrystallized grains is 5 μm to 20 μm. Further, the degree of rolling work in the final cold rolling is set to 90% or more. In this way, the following cubic assembly structure is obtained: in the state in which the tempering is performed to form a recrystallized structure, the intensity of the {200} plane obtained by X-ray diffraction on the rolled surface is set to I, and the fine powder is obtained. When the intensity of the {200} plane obtained by X-ray diffraction of copper is I ₀ , I/I ₀ >20.

Further, for example, in Patent Document 2, the degree of development of the cubic aggregate structure before the final cold rolling is increased, and the degree of processing in the final cold rolling is set to 93% or more. By further performing recrystallization annealing, a rolled copper foil in which the integrated intensity of the {200} plane is I/I ₀ ≧40 and the cubic aggregate structure is remarkably developed is obtained.

Further, for example, in Patent Document 3, the total degree of work in the final cold rolling step is set to 94% or more, and the degree of processing per rolling is controlled to be 15% to 50%. Thus, after recrystallization annealing, a predetermined crystal grain alignment state is obtained. In other words, the in-plane Δβ of the {111} plane of the rolled surface obtained by the X-ray diffraction pole pattern measurement with respect to the {200} plane is 10° or less. In addition, the ratio of the normalized diffraction peak intensity [b] of the normalized diffraction peak intensity [a] of the {200} plane as the cubic aggregate structure in the rolled surface to the {200} plane in the twin crystal relationship Is [a]/[b]≧3.

Thus, in the prior art, by increasing the total degree of processing of the final cold rolling step, the cubic aggregate structure of the rolled copper foil is developed after the recrystallization annealing step, thereby improving the bending resistance.

Further, in the rolled copper foil for FPC use, in order to improve the bonding strength with the substrate, for example, coarse particles may be attached thereto. Further, in this case, for example, as in Patent Documents 4 and 5, in order to uniformly adhere the roughened particles, a copper plating layer is formed on one surface or both surfaces of the rolled copper foil to smooth the surface, and then the adhesion is roughened. grain.

Conventional technical literature

Patent literature

Patent Document 1: Japanese Patent No. 3009383

Patent Document 2: Japanese Patent No. 3856616

Patent Document 3: Japanese Patent No. 4285526

Patent Document 4: Japanese Laid-Open Patent Publication No. 2005-340635

Patent Document 5: Japanese Laid-Open Patent Publication No. 2010-037585

However, in a rolled copper foil with a copper plating layer formed with a copper plating layer, for example, even if it is used The technique of Patent Documents 1 to 3 improves the bending resistance of the rolled copper foil, and visible fatigue fracture often occurs due to repeated bending. That is, in the rolled copper foil with a copper plating layer, the deterioration of the bending resistance is often seen.

An object of the present invention is to provide a rolled copper foil with a copper plating layer which can have excellent bending resistance even after a recrystallization annealing step even if a copper plating layer is formed.

According to a first aspect of the present invention, there is provided a rolled copper foil with a copper plating layer, comprising: a rolled copper foil after a final cold rolling step having a plurality of parallel crystal faces on a main surface or a back surface, and a recrystallization annealing step; and a copper plating layer formed on at least one of the main surface of the rolled copper foil or the back surface thereof and having a plurality of parallel crystal faces on the main surface or the back surface of the interface of the rolled copper foil. Among the plurality of crystal faces of the rolled copper foil, the intensity values of the diffraction peaks obtained by X-ray diffraction of the {111} plane, the {002} plane, and the {022} plane by the 2θ/θ method are each set to I. _R {111}, I _R {002}, I _R {022}, the fractions of the intensity values of the aforementioned diffraction peaks P _R {111}, P _R {002}, P _R {022} are set to: P _R {111}=[I _R {111}/(I _R {111}+I _R {002}+I _R {022})]×100, P _R {002}=[I _R {002}/(I _R {111}+I _R {002}+I _R {022})]×100, P _R {022}=[I _R {022}/(I _R {111}+I _R {002}+I _R { 022})]×100, in the above-mentioned plurality of crystal faces of the copper plating layer, X-ray diffraction obtained by the 2θ/θ method for the {111} plane, the {002} plane, and the {022} plane is obtained. Diffraction peak intensity values are each set to _{I M {111}, I M} {002}, I M {022}, the intensity values of each fraction of the diffraction peak _{P M {111}, P M} {002} , P _M {022} is set to: P _M {111}=[I _M {111}/(I _M {111}+I _M {002}+I _M {022})]×100, P _M {002} =[I _M {002}/(I _M {111}+I _M {002}+I _M {022})]×100, P _M {022}=[I _M {022}/(I _M {111} When +I _M {002}+I _M {022})] × 100, at least one of the following states is satisfied: P _M {111} ≧ 15.0 (1) satisfying the following formula (1), further satisfied The following equation (2) P _M {111}>(P _R {111}+5) (2); satisfies the following equations (3), (4) P _M {002}<(P _R {002 }-10)...(3)

The state of any one of P _M {002}>(P _R {002}+10) (4); satisfying the following equations (5), (6) P _M {022}<(P _R {022}- 10)...(5)

The state of any of P _M {022}>(P _R {022}+10) (6).

According to a second aspect of the present invention, there is provided a rolled copper foil with a copper plating layer according to the first aspect, which satisfies at least one of the following formulas (2), (4), and (6): P _M {111 }>(P _R {111}+5)...(2)

P _M {002}>(P _R {002}+10)...(4)

P _M {022}>(P _R {022}+10)...(6).

According to a third aspect of the present invention, there is provided a rolled copper foil with a copper plating layer according to the first or second aspect, wherein the rolled copper foil is formed of pure copper formed of tough or copper-free copper or The tough copper or oxygen-free copper is a low-concentration copper alloy of the mother phase, and the rolled copper foil adopts a form of a pure copper-type aggregate structure.

According to a fourth aspect of the present invention, there is provided a rolled copper foil with a copper plating layer according to the first to third aspects, wherein a thickness of the entire copper plating layer and the rolled copper foil is 1 μm or more and 20 μm or less, and a thickness of the copper plating layer. It is 0.1 μm or more and 1.0 μm or less.

According to a fifth aspect of the present invention, there is provided a rolled copper foil with a copper plating layer according to any one of the first to fourth aspects, which is a rolled copper foil with a copper plating layer for a flexible printed circuit board.

According to the present invention, there is provided a rolled copper foil with a copper plating layer which can have excellent bending resistance even after a recrystallization annealing step even if a copper plating layer is formed.

10‧‧‧Sliding bending test device

10s‧‧‧ stroke

10r‧‧‧bend radius

11‧‧‧Sample fixing plate

12‧‧‧ screws

13‧‧‧Vibration Transmission Department

14‧‧‧Oscillation driver

50‧‧‧Samples

S10‧‧‧Ingot preparation steps

S20‧‧‧ hot rolling step

S30‧‧‧ Repeat steps

S31‧‧‧ cold rolling step

S32‧‧‧ Annealing step

S40‧‧‧ final cold rolling step

S50‧‧‧ copper plating formation steps

S60‧‧‧ Surface treatment steps

DRAWINGS

1 is a flow chart showing a manufacturing procedure of a rolled copper foil with a copper plating layer according to an embodiment of the present invention; and FIG. 2 is a 2θ/θ of a rolled copper foil using tough pitch copper according to an embodiment of the present invention. The measurement chart of the X-ray diffraction performed by the method; FIG. 3 is a measurement chart of the X-ray diffraction performed by the 2θ/θ method in the rolled copper foil using the oxygen-free copper according to the embodiment of the present invention; The measurement chart of the X-ray diffraction according to the 2θ/θ method in the rolled copper foil using the tough pitch copper to which Ag is added according to the embodiment of the present invention; and FIG. 5 is a view showing the use of the Sn-added according to the embodiment of the present invention. A measurement chart of X-ray diffraction by a 2θ/θ method in a rolled copper foil of oxygen-free copper; and a measurement chart of X-ray diffraction by a 2θ/θ method according to Embodiment 1 of the present invention; Figure 2 is a measurement diagram of X-ray diffraction according to the 2θ/θ method in the second embodiment of the present invention; and Figure 8 is a measurement diagram of X-ray diffraction according to the 2θ/θ method in the third embodiment of the present invention; Figure 4 is a measurement diagram of X-ray diffraction according to the 2θ/θ method of Embodiment 4 of the present invention; Figure 10 is a fifth embodiment of the present invention. The measurement chart of the X-ray diffraction according to the 2θ/θ method; the 11th is the measurement chart of the X-ray diffraction according to the 2θ/θ method of the sixth embodiment of the present invention; and the twelfth embodiment is the seventh embodiment of the present invention. FIG. 13 is a measurement chart of X-ray diffraction according to the 2θ/θ method according to the eighth embodiment of the present invention; and FIG. 14 is a measurement chart of X-ray diffraction according to the second embodiment of the present invention; The measurement chart of the X-ray diffraction by the /θ method; the fifth figure is the measurement chart of the X-ray diffraction by the 2θ/θ method of Comparative Example 2; and the 16th drawing is the 2θ/θ method of the comparative example 3. FIG. 17 is a measurement diagram of X-ray diffraction according to the 2θ/θ method of Comparative Example 4; and FIG. 18 is a copper plating layer attached to the embodiment and the comparative example of the present invention. A schematic view of a sliding bending test apparatus for measuring the bending resistance of a rolled copper foil; and FIG. 19 is a graph showing the relationship between the thickness of the rolled copper foil and the number of bending fractures of the embodiment of the present invention.

<The findings obtained by the inventors, etc.>

As described above, in the rolled copper foil in which the copper plating layer is formed, even if the ratio of the {002} plane after heating is increased as in the above Patent Documents 1 to 3, the rolled copper foil having excellent bending resistance may be seen. Deterioration of bending resistance such as fatigue fracture occurs.

The inventors have found that such a fracture occurs as a starting point of a copper plating layer. The fracture occurring in the copper plating layer directly propagates to the rolled copper foil, and the rolled copper foil with the copper plating layer as a whole is considered to be a cause of deterioration of the bending resistance.

As a result of intensive studies by the present inventors, it has been found that, unlike the rolled copper foil which has excellent bending resistance by predetermined heating recrystallization, the copper plating layer hardly recrystallizes by heating at this time. That is, it is considered that the crystal structure at the time of formation by plating in the copper plating layer remains substantially as it is. Therefore, it is desirable that the copper plating layer has a crystal structure having sufficient bending resistance at the beginning of the formation of the copper plating layer.

Therefore, the inventors of the present invention have further studied and thought that the crystal structure of the copper plating layer which is formed at the beginning is different from that of the conventional copper plating layer, and the overall bending resistance of the rolled copper foil with the copper plating layer is improved. Further, the inventors have also found a method of forming a copper plating layer having such a crystal structure.

The present invention has been proposed based on the above findings discovered by the inventors.

<An embodiment of the present invention>

(1) Composition of rolled copper foil with copper plating

First, the configuration of a rolled copper foil with a copper plating layer according to an embodiment of the present invention will be described.

The rolled copper foil with a copper plating layer according to the present embodiment includes a rolled copper foil formed of oxygen-free copper, tough pitch copper, or a low-concentration copper alloy containing oxygen-free copper or tough copper as a mother phase, and a rolled copper foil. Copper plating on at least one side of the surface. In addition, the rolled copper foil with the copper plating layer is used for the purpose of use as a flexible wiring material for FPC, for example, and has a thickness of 1 μm or more and 20 μm or less. Further, among them, the thickness of the copper plating layer is 0.1 μm or more and 1.0 μm or less.

(summary of rolled copper foil)

The rolled copper foil provided in the rolled copper foil with the copper plating layer is formed into a plate shape having a rolling surface as a main surface, and has a plurality of parallel crystal faces on the rolled surface or the back surface. The rolled copper foil is, for example, casted from pure copper such as oxygen-free copper (OFC: Oxygen-Free Copper) or tough copper. The block is subjected to a hot rolling step, a cold rolling step, and the like described later to prepare a rolled copper foil after a final cold rolling step having a predetermined thickness and before a recrystallization annealing step. In other words, the rolled copper foil according to the present embodiment has a final cold rolling step of, for example, a total workability of 90% or more, preferably 94% or more, and more preferably 96% or more, and the thickness of the entire copper plating layer is included. For example, the above thickness is configured. Then, as described above, for example, if the copper-plated rolled copper foil is subjected to a recrystallization annealing step as a step of bonding to the substrate of the FPC, it is expected that the rolled copper foil which is tempered during recrystallization has Excellent bending resistance.

The oxygen-free copper which is a raw material of the rolled copper foil is a copper material having a purity of 99.96% or more as defined in JIS C1020 or the like. The oxygen content may not be completely zero, and may contain, for example, about several ppm of oxygen. Further, the tough pitch copper which is a raw material of the rolled copper foil is, for example, a copper material having a purity of 99.9% or more as defined in JIS C1100 or the like. In the case of tough pitch copper, the oxygen content is, for example, about 100 ppm to 600 ppm. The rolled copper foil formed of these raw materials is preferably in the form of, for example, a pure copper type aggregate structure (also referred to as a pure metal type aggregate structure). Alternatively, as the rolled copper foil, a predetermined addition material such as tin (Sn), silver (Ag), boron (B), or titanium (Ti) may be added to the oxygen-free copper or tough pitch copper to form a low-concentration copper. An alloy that adjusts the properties of various materials such as heat resistance. At this time, it is preferable that the addition amount of the additive material is such a range that the crystal alignment form of the pure copper-type aggregate structure is not formed by the pure copper of the parent phase.

Regarding the total degree of processing of the rolled copper foil in the final cold rolling step, if the thickness of the workpiece (copper sheet) before the final cold rolling step is set to T _B , and the thickness of the workpiece after the final cold rolling step is set to T _A is expressed as the total workability (%) = [(T _{B -} T _A ) / T _B ] × 100. By setting the total degree of work within the above range, the ratio of the {002} plane after heating in the recrystallization annealing step is increased, and a rolled copper foil having high bending resistance can be obtained.

(summary of copper plating)

The copper plating layer provided in the rolled copper foil with a copper plating layer is formed, for example, on the surface of at least one of the rolled surface of the main surface of the rolled copper foil or the back surface thereof by plating or the like. The copper plating layer has, for example, a plurality of crystal faces which are the outermost main surface of the rolled copper foil to which the copper plating layer is attached or which are parallel to the back surface of the interface of the rolled copper foil. The copper plating layer according to the present embodiment is formed to be thinner than, for example, a rolled copper foil, and has a thickness of, for example, 0.01 μm or more and 1.0 μm or less.

By forming such a thickness, for example, the surface of the rolled copper foil is flattened by a copper plating layer which is a base of the roughened particles and the rustproof layer to be described later, and the roughened particles can be uniformly adhered or the rustproof layer can be formed. Formed evenly. Further, by forming the copper plating layer to be thinner than the rolled copper foil in this manner, it is easy to improve the bending resistance of the entire rolled copper foil with the copper plating layer. In the present embodiment, in order not to cause an influence on practical use, a thickness of 1.0 μm is used as an upper limit value, and the copper plating layer is formed to be as thin as possible.

(Crystal structure of copper plating)

The plurality of crystal faces of the copper plating layer provided in the rolled copper foil with the copper plating layer have a predetermined state with respect to the plurality of crystal faces of the rolled copper foil. Such a state can be identified by using a diffraction peak obtained by X-ray diffraction performed in accordance with the 2θ/θ method as follows.

That is, in the plurality of crystal faces of the rolled copper foil, the intensity values of the diffraction peaks obtained by the X-ray diffraction performed on the {111} plane, the {002} plane, and the {022} plane by the 2θ/θ method are each Set to I _R {111}, I _R {002}, I _R {022}. Further, the fraction of the intensity values of the respective diffraction peaks is set to P _R {111}, P _R {002}, and P _R {022}.

The fraction of the intensity values of the respective diffraction peaks is expressed by the following formula: P _R {111}=[I _R {111}/(I _R {111}+I _R {002}+I _R {022})]× 100, P _R {002}=[I _R {002}/(I _R {111}+I _R {002}+I _R {022})]×100,P _R {022}=[I _R {022} /(I _R {111}+I _R {002}+I _R {022})]×100.

Further, in the plurality of crystal faces of the copper plating layer, the intensity values of the diffraction peaks obtained by the X-ray diffraction performed on the {111} plane, the {002} plane, and the {022} plane in accordance with the 2θ/θ method are each set. I _M {111}, I _M {002}, I _M {022}. Further, the fraction of the intensity values of the respective diffraction peaks is set to P _M {111}, P _M {002}, P _M {022}.

The fraction of the intensity values of the respective diffraction peaks is represented by the following formula: P _M {111}=[I _M {111}/(I _M {111}+I _M {002}+I _M {022})]× 100, P _M {002}=[I _M {002}/(I _M {111}+I _M {002}+I _M {022})]×100,P _M {022}=[I _M {022} /(I _M {111}+I _M {002}+I _M {022})]×100.

At this time, the copper plating layer has a crystal structure satisfying the following formula (1), P _M {111} 15.0...(1).

Further, the copper plating layer has a crystal structure in at least one of the following states: a state satisfying the following formula (2) P _M {111}>(P _R {111}+5) (2); Equation (3), (4) P _M {002}<(P _R {002}-10)...(3)

The state of any one of P _M {002}>(P _R {002}+10) (4); satisfying the following equations (5), (6) P _M {022}<(P _R {022}- 10)...(5)

The state of any of P _M {022}>(P _R {022}+10) (6).

Further, it is preferable that the copper plating layer has the above formulas (2), (4), and (6), that is, P _M {111}>(P _R {111}+5) (2)

_{P M {002}> (P} R {002} +10) ... (4)

_{P M {022}> (P} R {022} +10) ... (6) at least any one of the crystal structure.

The meaning of the copper plating layer having the above crystal structure will be described below.

(The role of crystal structure)

As described above, the rolled copper foil in the present embodiment has an increased ratio of the {002} plane after the recrystallization annealing step, and has excellent bending resistance.

On the other hand, the crystal structure of the copper plating layer satisfies the above formula (1) in the state after the final cold rolling step and before the recrystallization annealing step, and further satisfies the formula (2), (3) or (4), (5). Or at least one of (6). By doing so, the copper plating layer can obtain excellent bending resistance regardless of the recrystallization annealing step.

Regardless of the copper plating layer, in general, when a layer is formed by electroplating, liquid phase epitaxial growth which is affected by the crystal orientation of the substrate easily occurs. In other words, for example, in a conventional copper-plated rolled copper foil, the copper plating layer is easily subjected to liquid crystal epitaxial growth by the crystal orientation of the rolled copper foil as a base, and is liable to become a crystal with the rolled copper foil. Oriented to the same crystal alignment. As will be described later, the copper plating layer is formed, for example, for the rolled copper foil after the final cold rolling step and before the recrystallization annealing step. At this time, the crystal alignment of the rolled copper foil becomes a crystal alignment state of the rolled aggregate structure. Therefore, the copper plating layer should also be in the same state as the crystal alignment of the rolled aggregate structure.

When such a copper-plated rolled copper foil is heated and the rolled copper foil is softened by recrystallization, the crystal orientation of the rolled aggregate structure of the rolled copper foil changes to the crystal orientation of the recrystallized aggregate structure, thereby rolling the copper foil. Excellent bending resistance is obtained. However, as described above, according to this The inventors discovered that the copper plating layer hardly recrystallizes by such heating.

In the recrystallization annealing step, the driving force for the change in the crystal orientation of the rolled copper foil is: the processing strain accumulated in the rolled copper foil due to the rolling process in the final cold rolling step, and the heating by recrystallization annealing. Thermal energy. However, even if the crystal alignment of the copper plating layer is changed, the heat that can be used as the driving force at this time is only the heat generated by the heating. Therefore, it is considered that in the copper plating layer, since the driving force is insufficient, the crystal alignment change hardly occurs, and the crystal alignment state of the rolled aggregate structure stays in the state of epitaxial growth. Due to such crystal alignment, sufficient bending resistance cannot be obtained in the copper plating layer.

Therefore, the inventors of the present invention have conducted intensive studies in order to form a copper plating layer, and the crystal structure of the copper plating layer is at least not in the crystal alignment state of the rolled aggregate structure. The result shows that if the rolled copper foil with the copper plating is in the state after the final cold rolling step and before the recrystallization annealing step, it has the above formula (1), and further satisfies the formula (2), (3) or (4). The crystal structure of at least one of (5) or (6) forms a copper plating layer excellent in bending resistance.

Although the detailed mechanism for exhibiting high bending resistance of such a copper plating layer is still under investigation, it can be said that at least the crystal structure of the copper plating layer is not in an epitaxial state by satisfying the predetermined formula described above.

In other words, when the rolled aggregate structure of the rolled copper foil according to the present embodiment is subjected to X-ray diffraction by the 2θ/θ method, the {022} plane represents a main peak. Then, the diffraction peak of the {002} plane exhibits the second strongest intensity. On the other hand, the diffraction peak intensity value of the {111} plane is extremely small.

Therefore, the present inventors focused on the diffraction peaks of the three faces of the {111} plane, the {002} plane, and the {022} plane, and the fractions of the respective diffraction peak intensity values P _R {111}, P _R {002 }, P _R {022}, and the fractions of the diffraction peak intensity values of the copper plating layers corresponding thereto, P _M {111}, P _M {002}, P _M {022}. Thus, it is possible to judge whether or not the state in which the crystal of the rolled copper foil and the copper plating layer are aligned is the same.

In other words, in the rolled copper foil according to the present embodiment, for example, the fraction P _R {111} of the diffraction peak intensity value of the {111} plane should be extremely small. However, by satisfying the formula (1), the fraction P _M {111} of the diffraction peak intensity value of the {111} plane of the copper plating layer according to the present embodiment is not such a small fraction, and the display maintains a predetermined fraction. The {111} plane is present in the crystal structure of the copper plating.

In addition, it can be said that if the copper plating layer has a crystal structure satisfying at least one of the formula (2), (3) or (4), (5) or (6), it does not become an epitaxial state. It is in a state different from the crystal alignment of the rolled copper foil.

That is, the formula (2) is that the P _M {111} of the copper plating layer is sufficiently larger than the P _R {111} of the rolled copper foil, and the crystal alignment state of the copper plating layer is different from that of the rolled copper foil.

Further, the formula (3) is that the P _M {002} of the copper plating layer is extremely small compared to the P _R {002} of the rolled copper foil. Further, the formula (4) is that the P _M {002} of the copper plating layer is extremely larger than the P _R {002} of the rolled copper foil. Thus, both equations (3) and (4) indicate that P _M {002} of the copper plating layer is different from P _R {002} of the rolled copper foil.

Further, the formula (5) is that the P _M {022} of the copper plating layer is extremely small compared to the P _R {022} of the rolled copper foil. Further, the formula (6) is that the P _M {022} of the copper plating layer is extremely larger than the P _R {022} of the rolled copper foil. Thus, both equations (5) and (6) indicate that P _M {022} of the copper plating layer is different from P _R {022} of the rolled copper foil.

As described above, if the copper plating layer satisfies any one of the above formulas (2), (3) or (4), (5) or (6), it can be said that the crystal alignment state of the copper plating layer does not undergo epitaxial growth, and The rolled copper foil is different. At this time, instead of satisfying only one of the states of the formula (2), (3), or (4), (5), or (6), a plurality of states may be satisfied.

Further, it can be said that it is preferable that at least one of the above formulas (2), (4), and (6) is satisfied by the copper plating layer, and the crystal structure of the copper plating layer is not only different from that of the rolled copper foil, but also becomes more susceptible to bending resistance. Crystal structure. In order to carry out intensive studies to satisfy the meanings of the above formulas (2), (4), and (6), it is known that at least the {002} plane exists in a large amount, and the bending resistance of a copper material such as a rolled copper foil is improved. Therefore, it is presumed that, for example, by satisfying the formula (4), the bending resistance of the copper plating layer is also improved.

Further, on the other hand, in the case where the copper plating layer does not satisfy the above formula (1), or any of the above formulas (2), (3) or (4), (5) or (6) is not satisfied, It can be said that the crystal alignment state of the copper plating layer is epitaxially grown with respect to the crystal alignment of the rolled copper foil, and is substantially equivalent to the rolled copper foil.

(Other configurations of rolled copper foil with copper plating)

On the copper plating layer of the rolled copper foil to which the copper plating layer is attached, for example, a roughened copper plating layer, a capsule copper plating layer, and a rustproof layer can be provided in the above-described order. The roughened copper plating layer has coarsened particles. The roughened particles are, for example, copper (Cu) monomers (or simple substances) or iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), zinc (Zn) in copper. At least one or more kinds of metal particles having a diameter of about 1 μm. The capsule copper plating is a so-called packaging coating in which coarsened grains are grown into knob-like projections. The rustproof layer has a laminated structure in which, for example, a nickel plating layer, a zinc plating layer, a trivalent chromizing layer, and a decane coupling layer are formed in the above-described order.

(2) Method for producing rolled copper foil with copper plating

In order to obtain the copper plating layer according to the present embodiment, the inventors of the present invention have a state in which the rolled copper foil before the final cold rolling step and before the recrystallization annealing step has a crystal alignment different from the crystal orientation in which epitaxial growth occurs, that is, with rolling. The state of the organization of different crystal alignments has been studied intensively.

Specifically, it is considered that a chemical which can be suppressed (hereinafter also referred to as an epitaxial growth inhibitor or a non-plating agent) can be added to the plating bath in the case of forming a copper plating layer so that the copper plating layer does not protrude relative to the rolled copper foil. Crystal growth and various additives were tried. As a result, it was confirmed that a predetermined additive used for plating or the like as a non-plating agent suppresses epitaxial growth of the copper plating layer. Specifically, a new effect as a non-exhalation agent among the predetermined additives used as a brightener has been found.

Next, based on the above findings, a method of manufacturing a rolled copper foil with a copper plating layer according to an embodiment of the present invention will be described with reference to FIG. Fig. 1 is a flow chart showing a manufacturing procedure of a rolled copper foil with a copper plating layer according to the present embodiment.

(Preparation step S10 of ingot)

As shown in Fig. 1, first, a rolled copper foil portion of a rolled copper foil with a copper plating layer was produced.

In other words, casting is performed by casting pure copper such as oxygen-free copper (OFC) or tough pitch copper as a raw material to prepare an ingot (ingot). The ingot is formed into a plate shape having a predetermined thickness and a predetermined width, for example. As the raw material, oxygen-free copper or tough pitch copper can also be used as a low-concentration copper alloy to which a predetermined additive material is added in order to adjust various characteristics of the rolled copper foil.

The characteristics of the rolled copper foil which can be adjusted with the additive material are, for example, heat resistance. As described above, the recrystallization annealing step for obtaining high bending resistance in the rolled copper foil for FPC is also performed as a step of bonding to a substrate of FPC, for example. The heating temperature at the time of bonding is set in accordance with, for example, the curing temperature of the substrate formed of a resin such as FPC, the curing temperature of the adhesive to be used, and the like, and the temperature conditions are wide and varied. In order to mix the softening temperature of the rolled copper foil with the heating temperature set as described above, an additive which can adjust the heat resistance of the rolled copper foil may be appropriately added.

As the ingot used in the present embodiment, an ingot in which no additive material is added and an ingot in which several types of additive materials are added are exemplified in Table 1 below. Here, in the range of the addition amount of the additive material shown in Table 1, the state of the crystal alignment of the rolled copper foil adopts the form of a pure copper type aggregate structure.

In the representative example of the additive material which increases or decreases the heat resistance, the additive material and the other additive materials shown in Table 1 are, for example, tin (Sn), silver (Ag), or boron (B) added in an amount of about 10 ppm to 2,000 ppm. ), any of niobium (Nb), titanium (Ti), nickel (Ni), zirconium (Zr), vanadium (V), manganese (Mn), hafnium (Hf), tantalum (Ta), and calcium (Ca) Or an example of multiple elements. Alternatively, there is an example in which Ag is added as the first additive element, and any one or more of the above elements are added as the second additive element. In addition, chromium (Cr), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), cadmium (Cd), indium (In), tin (Sn), and antimony may be added in a small amount. Sb), gold (Au), etc.

Here, the composition of the ingot is substantially maintained as it is in the rolled copper foil after the final cold rolling step S40 to be described later, and when the additive material is added to the ingot, the ingot and the rolled copper foil form substantially the same additive material. concentration.

In addition, the temperature conditions in the annealing step S32 to be described later are appropriately changed depending on the heat resistance determined by the copper material or the additive material. However, the copper material, the additive material, the change in the temperature condition of the annealing step S32 performed therewith, and the like have little effect on the effects of the present embodiment.

(hot rolling step S20)

Next, the prepared ingot is subjected to hot rolling to obtain a sheet material having a thickness smaller than a predetermined thickness after casting.

(repeat step S30)

Next, repeating step S30 of repeating the predetermined number of cold rolling steps S31 and annealing step S32 is performed. That is, the sheet material processed and solidified by cold rolling is subjected to an annealing treatment to anneal the sheet material, thereby relaxing the processing and solidification. By repeating this operation a predetermined number of times, a copper strip called "blank" is obtained. When an additive material or the like which adjusts heat resistance is added to the copper material, the temperature condition of the annealing treatment is appropriately changed depending on the heat resistance of the copper material.

Here, in step S30, the annealing step S32 in the repeating process is referred to as an "intermediate annealing step". Further, the annealing step S32 which is performed at the last of the repetition, that is, before the final cold rolling step S40 described later, is referred to as a "final annealing step" or a "blank annealing step". In the billet annealing step, the copper strip (blank) is subjected to a blank annealing treatment to obtain an annealed billet. In the billet annealing step, the temperature conditions are also appropriately changed depending on the heat resistance of the copper material. At this time, the billet annealing step is preferably carried out under temperature conditions which can sufficiently alleviate the processing strain caused by the above respective steps, for example, under substantially the same temperature conditions as the full annealing treatment.

(final cold rolling step S40)

Next, a final cold rolling step S40 is performed. The final cold rolling is also referred to as final processing cold rolling, and the annealed billet is continuously subjected to cold rolling as a final processing a plurality of times to form a thin copper foil. At this time, the total degree of work in the final cold rolling step S40 is set to 90% or more, preferably 94% or more, and more preferably 96% or more, to obtain a rolled copper foil having high bending resistance. Thus, after the recrystallization annealing step, a rolled copper foil which is easy to obtain excellent bending resistance is obtained.

By the above operation, the rolled copper foil in the copper-plated rolled copper foil according to the present embodiment is produced.

(copper plating forming step S50)

Next, a copper plating layer is formed on at least one of the rolled surface of the rolled copper foil or the back surface thereof.

When the copper plating layer is formed, the rolled copper foil is sequentially immersed in a degreasing bath or an acid washing bath, and the surface of the rolled copper foil is washed. That is, in the degreasing bath, cathodic electrolytic degreasing is performed using an alkaline solution such as an aqueous solution of sodium hydroxide (NaOH). Next, in the acid washing bath, the surface of the rolled copper foil is subjected to an acid washing with an acidic solution such as an aqueous solution of sulfuric acid (H ₂ SO ₄ ) or a copper etching solution to neutralize the residual alkaline solution on the surface, and at the same time, the surface is The copper oxide film (CuO) or the like formed thereon is removed.

For the formation of the copper plating layer, for example, plating or the like can be used. As the plating bath, for example, an acid copper plating bath such as a copper sulfate-sulfuric acid bath filled with an aqueous solution containing copper sulfate (CuSO ₄ ) and sulfuric acid (H ₂ SO ₄ ) as a main component can be used. Here, from the viewpoint of cost and the like, a copper sulfate-sulfuric acid bath or the like is used, but a solution or the like which can be used in the copper plating bath is not limited thereto.

At this time, it is preferable to make the plating current density smaller than the limiting current density. By doing so, generation of unevenness on the surface is suppressed, and a flatter copper plating layer can be obtained. However, when the plating current density is high, the productivity is improved. Therefore, the preferred plating current density is in a range smaller than the limiting current density, and And set it as high as possible. The criteria for plating conditions are exemplified below. However, the following conditions are an example of plating conditions and are not limited to this. The liquid composition, liquid temperature, and electrolysis conditions of a copper sulfate-sulfuric acid bath or the like can be selected from a wide range.

Copper sulfate pentahydrate: 20g/L~300g/L

Sulfuric acid: 10g/L~200g/L

Liquid temperature: 15 ° C ~ 50 ° C

Plating current density: 1A/dm ² ~30A/dm ² (less than the limiting current density)

Plating time: 1 second ~ 60 seconds

Further, in the copper sulfate-sulfuric acid bath, as an additive, for example, bis(3-sulfopropyl)dithiodisodium (or sodium polydithiodipropane sulfonate, hereinafter also referred to as SPS), 3-mercapto-1 is added. a compound having a mercapto group (-SH) such as propanesulfonic acid (hereinafter also referred to as MPS). Further, as other additives, a chemical liquid and a leveling agent containing polyethylene glycol (PEG, Poly Ethylene Glycol) as a main component are added.

A rolled copper foil having a surface cleaned is immersed in an acid copper plating bath to which such an additive is added, and a plating treatment using a rolled copper foil as a cathode is performed, and a copper plating layer is formed on one surface or both surfaces of the rolled copper foil. In this way, the rolled copper foil before the final cold rolling step and before the recrystallization annealing step is in a state of crystal alignment different from the crystal orientation in which epitaxial growth occurs, that is, a state in which the crystal is aligned with the rolled aggregate structure, thereby The copper plating layer according to the embodiment is obtained. In other words, components such as SPS and MPS in such a chemical solution function as epitaxial growth inhibitors (non-plating agents).

Usually, a chemical liquid containing SPS, MPS or the like as a main component functions as a brightening agent in a copper plating treatment. In this case, the chemical solution is usually added in an amount of about 5 mg to 10 mg per SP liter of the plating solution.

However, the present inventors have found that by adding, for example, SPS, MPS, or the like in an amount larger than usual, crystals which are epitaxially grown can be obtained for the rolled copper foil after the final cold rolling step and before the recrystallization annealing step. A copper plating that is aligned with different crystals. According to the findings of the inventors of the present invention, it is presumed that when a copper plating layer is formed, some energy is accumulated in the copper plating layer by using a non-plating agent such as SPS or MPS added in an amount larger than usual. Further, it is considered that the energy has a size such that the copper plating layer can perform crystal growth without affecting the crystal orientation of the rolled copper foil, that is, the copper plating layer does not undergo epitaxial growth with respect to the rolled copper foil.

At present, the inventors have speculated that the application of such energy to the copper plating layer may occur by any of the following effects. That is, on the one hand, it is considered that the main addition is more than when using a general gloss agent. A lot of SPS and so on. Further, on the other hand, in addition to the large addition of SPS or the like, it is considered to be some interaction of such SPS and the like with other chemical liquids. The other chemical liquid is considered to be a main component of another chemical liquid added to the plating liquid, or a component which is not a main component, or/and not only a chemical liquid, but also some components of the plating liquid.

Such effects, uses, and methods of use of SPS and the like discovered by the present inventors are completely different from the conventional effects, uses, and methods of use of these compounds as a glossing agent, and are novel effects, uses, and methods of use.

The above viewpoint is also apparent from the comparison of the roughened foils of the above-mentioned Patent Documents 4 and 5 and the rolled copper foil with the copper plating layer according to the above-described embodiment.

In Patent Documents 4 and 5, in order to uniformly adhere the roughened tumor, a copper plating layer is formed on the surface of the rolled copper foil. The purpose at this time is to reduce the thickness of the copper plating layer by changing the current density, and to reduce the depression called a crater on the surface of the copper plating layer, and to uniformize the roughening tumor formed thereon. In Patent Documents 4 and 5, the copper plating layer is in a state in which epitaxial growth occurs in the crystal alignment of the rolled copper foil, which can be easily estimated for the following reasons.

First, in Patent Document 4, a drug such as SPS is not used. Further, other disclosures regarding the method of forming a copper plating layer are also well known. From this, it can be presumed that the copper plating layer is in a state in which epitaxial growth occurs in the crystal alignment of the rolled copper foil.

Further, in Patent Document 5, an example in which SPS is used is also disclosed. However, from the results of the above examples, it is presumed that the copper plating layer is in a state in which epitaxial growth occurs in the crystal alignment of the rolled copper foil. Specifically, the thicknesses of the copper plating layers of Examples 1, 4 and Comparative Example 2 of Patent Document 5 were both about 0.1 μm. In addition, it does not matter whether or not SPS is used, and the number of bending life times is substantially the same as each other, and is 4.1 × 10 ⁶ to 4.5 × 10 ⁶ times. Here, the number of bending lifes can be used as one of the indexes of the bending resistance, and it can be said that the higher the bending life count, the higher the bending resistance. As described above, even if the copper plating layer using SPS is used, only the bending resistance equivalent to that of the copper plating layer not using SPS is obtained, and therefore, it is considered that the epitaxial growth occurs with respect to the rolled copper foil.

As described above, in Patent Literatures 4 and 5, it is considered that the bending resistance of the rolled copper foil having the copper plating layer is deteriorated by imparting the copper plating layer in which the epitaxial growth occurs to the bending resistance of the rolled copper foil. In the number of bending fractures described in Patent Document 4 and Patent Document 5, the number of bending fractures described in the examples of the present invention and the like described later is different depending on measurement conditions such as the bending radius at the time of bending the copper foil, and thus cannot be simply Compare.

(surface treatment step S60)

The surface of the copper plating layer formed by the above steps is subjected to a predetermined treatment to produce a rolled copper foil with a copper plating layer according to the present embodiment.

Here, as a predetermined surface treatment, for example, a treatment such as roughening a copper plating layer, a capsule copper plating layer, and a rustproof layer on the copper plating layer in this order can be performed. However, these processes described below may not be performed.

First, an example in which a roughened copper plating layer is formed on a copper plating layer will be described.

As the plating bath for forming the roughened copper plating layer, an acid copper plating bath such as a copper sulfate-sulfuric acid bath can be used. Further, one or more ionic components such as iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), and zinc (Zn) may be blended in the acid copper plating bath.

Further, in the rough copper plating, electrolysis is performed with a copper plating layer as a base and a high current density equal to or higher than the limiting current density, that is, a current density at which a so-called baking is formed. However, at this time, the liquid composition, liquid temperature, and electrolysis conditions of a copper sulfate-sulfuric acid bath or the like can be selected from a wide range. As a result, the electrodeposit and the precipitate adhere to the copper plating layer, and they are further enlarged to obtain, for example, coarse particles having a diameter of about 1 μm.

Next, an example of forming a capsule copper plating layer will be described.

That is, the roughened particles of the roughened copper plating layer are subjected to coating plating with a current lower than the limiting current density of the plating bath to grow the coarsened grains into the knob-shaped copper particles. However, when the roughened particles are not kept in a minute state, the capsule copper plating layer may not be formed. At this time, the liquid composition, liquid temperature, and electrolysis conditions of the copper sulfate-sulfuric acid bath or the like can be selected from a wide range. Further, at this time, an organic additive material may be added to the plating bath.

Next, an example of forming a rustproof layer will be described.

The rustproof layer is also referred to as a post-treatment plating layer, whereby sufficient rust prevention performance can be obtained. First, a nickel plating layer or a nickel alloy plating layer is formed to suppress the diffusion of copper. Next, a zinc plating layer or a zinc alloy plating layer is formed to improve heat resistance. Next, a trivalent chromium oxide layer is formed using a trivalent chromium type reaction type chromate solution or the like. After that, as a chemical treatment film, for example, a decane coupling layer is formed, and adhesion to a substrate of FPC or the like is improved.

Through the above operation, the surface treatment of the copper plating layer is completed.

(3) Manufacturing method of flexible printed circuit board

Next, the flexibility of using a copper-plated rolled copper foil according to an embodiment of the present invention A method of manufacturing a printed circuit board (FPC) will be described.

(Recrystallization annealing step (CCL step))

First, the rolled copper foil with a copper plating layer according to the present embodiment is cut into a predetermined size, and bonded to a substrate of an FPC made of, for example, a resin such as polyimide, to form a CCL (Copper-clad laminate (Copper) Clad Laminate)). In this case, a method of forming a three-layer material CCL by bonding with an adhesive, and a method of directly bonding the adhesive without using an adhesive to form a two-layer material CCL may be used. When an adhesive is used, the adhesive such as the above-described decane coupling agent is cured by heat treatment, and the surface of the rolled copper foil with the copper plating layer having the copper plating layer and the roughened particles attached to the copper plating layer is obtained. It is combined with the substrate to be composited. When the adhesive is not used, the surface of the rolled copper foil with the copper plating layer having the copper plating layer and the roughened particles attached to the copper plating layer is directly adhered to the substrate by heating and pressurization. The heating temperature and time may be appropriately selected in accordance with the curing temperature of the adhesive or the substrate, and may be, for example, a temperature of from 150 ° C to 400 ° C and not more than 1 minute and 120 minutes.

As described above, the heat resistance of the rolled copper foil provided in the rolled copper foil with the copper plating layer is adjusted in accordance with the heating temperature at this time. Therefore, the rolled copper foil in a state of being solidified by the final cold rolling step S40 is softened by the above heating and is tempered in recrystallization. That is, the CCL step of laminating the rolled copper foil with the copper plating layer on the substrate also serves as a recrystallization annealing step for the rolled copper foil of the rolled copper foil with the copper plating layer.

In this way, the CCL step also serves as a recrystallization annealing step, and in the step of bonding the rolled copper foil with the copper plating layer to the substrate, the rolled copper foil can be cured in the final cold rolling step S40. The treatment of the rolled copper foil with the copper plating layer can prevent deformation such as elongation, wrinkles, and bending when the rolled copper foil with the copper plating layer is bonded to the substrate.

Further, the softening of the rolled copper foil as described above means that a rolled copper foil having a recrystallized structure, that is, a rolled copper foil having a recrystallized structure is obtained by a recrystallization annealing step. Specifically, it is possible to obtain a rolled copper foil having an improved ratio of {002} plane and excellent bending resistance.

On the other hand, the copper plating layer does not have a driving force for recrystallization such as processing strain as that of the rolled copper foil. Therefore, from the viewpoint of crystallography, such a crystal structure is difficult to change like the above-described rolled copper foil. That is, in the copper plating layer, the crystal alignment remains substantially constant before and after the entire recrystallization annealing step. At this time, the crystal alignment of the copper plating layer is not in a state in which epitaxial growth occurs, that is, it is not in the crystal alignment equivalent to the rolled aggregate structure. Through this, the copper plating is no longer Excellent bending resistance before or after the crystallization annealing step.

(surface processing step)

Next, a surface processing step is performed on the rolled copper foil to which the copper plating layer is attached to the substrate. In the surface processing step, a step of forming a copper wiring or the like by a method such as etching using a copper plating layer is performed, and a plating process is performed to improve the connection reliability of the copper wiring and other electronic components. A surface treatment step of the surface treatment, and a protective film forming step of forming a protective film such as a solder resist film to cover a portion of the copper wiring in order to protect the copper wiring or the like.

Through the above operation, an FPC using the rolled copper foil with a copper plating layer according to the present embodiment was manufactured.

<Other Embodiments of the Invention>

The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the invention.

For example, in the above-described embodiment, Sn, Ag, or the like is mainly used as an additive for adjusting the heat resistance of the rolled copper foil provided in the rolled copper foil with a copper plating layer, but the additive is not limited to Sn, Ag, and the like. Representative examples and the like. Further, the characteristics that can be adjusted by adding materials are not limited to heat resistance, and the materials to be added can be appropriately selected according to various characteristics to be adjusted.

Further, in the above embodiment, the CCL step in the manufacturing step of the FPC also serves as a recrystallization annealing step for the rolled copper foil, but the recrystallization annealing step may be performed as a step different from the CCL step.

Further, in the above embodiment, the rolled copper foil with the copper plating layer is used for FPC use, but the use of the rolled copper foil with the copper plating layer is not limited thereto, and can also be applied to a negative electrode set such as a lithium ion secondary battery. Electric copper foil, other uses that require bending resistance. In addition, the thickness of the rolled copper foil with a copper plating layer may be ultrathin or less than 20 μm, or may be more than 20 μm, depending on various applications such as FPC use.

Further, in the above embodiment, the copper plating layer is made thinner than the rolled copper foil, but it is not limited thereto. Even if the copper plating layer is made thicker than the rolled copper foil, for example, the effect of the present invention can be obtained as a whole: the bending resistance of the rolled copper foil with the copper plating layer is improved.

Further, in the above embodiment, the rolled copper foil adopts a form of a pure copper type aggregate structure, but Not limited to this. For example, in the case of use in addition to the use of FPC, it is also possible to adopt an alloy-type aggregate structure.

Further, in the above embodiment, the roughened copper plating layer, the capsule copper plating layer, and the rustproof layer are provided on the copper plating layer, but the combination of these layers is arbitrary. For example, in the case where the roughened particles are small, the capsule copper plating layer may not be provided. Further, instead of providing a roughened copper plating layer or a capsule copper plating layer, a rustproof layer may be directly provided on the copper plating layer. Further, depending on the application of the rolled copper foil to which the copper plating layer is applied, that is, in the use other than the use of the FPC, the adhesion to the substrate may not be considered first, and the configuration on the copper plating layer may be omitted. , for example, no coarsening.

Further, in the above-described embodiment, the total degree of work in the final cold rolling step S40 is set to 90% or more, and the rolled copper foil is excellent in bending resistance, but the total degree of processing in the final cold rolling step is set to For example, less than 90%, it is also possible to obtain the effect of the copper plating layer which improves the bending resistance independently of this. Therefore, the total processing degree of the low-pressure copper foil can be reduced, for example, when the total processing degree is as low as less than 90% or less than 80%, etc., as long as a certain degree of bending resistance is obtained. load.

Further, in the above-described embodiment, the method for producing a copper plated rolled copper foil having a crystal structure in which a copper plating layer does not form a rolled copper foil is found in epitaxial growth in plating or the like using an additive such as SPS or MPS. The prescribed effect of the inhibitor (non-extraction agent). However, the use of the SPS and MPS is not the essence of the invention itself, and other additives having a function as a non-plating agent can also be used. Thus, the effects of the present invention can be sufficiently obtained.

After all, the gist of the present invention lies in the following two points: the copper plating layer of the rolled copper foil with the copper plating layer does not undergo epitaxial growth and does not have the same crystal structure as the rolled copper foil, and thus the copper plating layer obtains excellent bending resistance. .

Here, in order to achieve the effects of the present invention, all of the steps listed above are not necessarily required. The various conditions exemplified in the above embodiment and the examples to be described later are also exemplified, and can be appropriately changed.

[Examples]

Hereinafter, examples related to the present invention will be described together with comparative examples.

(1) Production of rolled copper foil with copper plating

Hereinafter, the steps of producing the copper-plated rolled copper foil according to Examples 1 to 32 and Comparative Examples 1 to 16 will be described.

(Production of rolled copper foil)

First, a rolled copper foil is produced. There are four kinds of raw materials used: toughness copper with a purity of 99.9%, oxygen-free copper with a purity of 99.99%, toughness with a purity of 99.9% added with an added amount controlled in the range of 180 ppm to 220 ppm, and addition amount control Oxygen-free copper having a purity of Sn of 99.99% added in the range of 30 ppm to 90 ppm. The rolled copper foil was obtained from these ingots by the same steps and methods as those of the above embodiment. At this time, a rolled copper foil having a thickness of 8.0 μm, 11.0 μm, 16.5 μm, and 17.0 μm was produced for both the examples and the comparative examples. Further, at this time, various production conditions in the examples and the comparative examples were set to match.

At this time, the plate material having a thickness of 8 mm obtained in the hot rolling step is held at a temperature of about 600 ° C to 800 ° C for 30 seconds to 2 minutes in accordance with the thickness of each of the copper material and the copper strip in the intermediate annealing step. Further, in the billet annealing step, the billet is held at a temperature of about 500 to 750 ° C for about 30 seconds to 2 minutes depending on the thickness of each of the copper material and the billet material. Thus, for example, even if the materials are the same, since the heat resistance changes depending on the thickness of the copper material, the temperature can be lowered as the thickness becomes thinner.

Further, the total degree of processing corresponding to the material in the final cold rolling step and the thickness t of the finally obtained rolled copper foil is shown below.

● Calendered copper foil using tough copper: total processing degree 90.0%~91.8%

. T8.0μm: t80μm→(90.0%)→t8.0μm

. T11.0μm: t125μm→(91.2%)→t11.0μm

. T16.5μm: t200μm→(91.8%)→t16.5μm

. T17.0μm: t200μm→(91.5%)→t17.0μm

●Used copper foil with oxygen-free copper: total processing degree 94.3%~94.6%

. T8.0μm: t140μm→(94.3%)→t8.0μm

. T11.0μm: t200μm→(94.5%)→t11.0μm

. T16.5μm: t300μm→(94.5%)→t16.5μm

. T17.0μm: t315μm→(94.6%)→t17.0μm

●Used rolled copper foil with tough pitch copper added with Ag: total processing degree 96.9%~97.8%

. T8.0μm: t360μm→(97.8%)→t8.0μm

. T11.0μm: t400μm→(97.3%)→t11.0μm

. T16.5μm: t550μm→(97.0%)→t16.5μm

. T17.0μm: t550μm→(96.9%)→t17.0μm

●Used copper foil with oxygen-free copper added with Sn: total processing degree 96.9%~97.8%

. T8.0μm: t360μm→(97.8%)→t8.0μm

. T11.0μm: t400μm→(97.3%)→t11.0μm

. T16.5μm: t550μm→(97.0%)→t16.5μm

. T17.0μm: t550μm→(96.9%)→t17.0μm

(Production of rolled copper foil with copper plating)

Next, the rolled copper foil obtained as described above was subjected to copper plating to prepare a rolled copper foil with a copper plating layer.

First, in the electrolytic degreasing which cleans the surface of the rolled copper foil, in an aqueous solution containing 40 g/L of sodium hydroxide and 20 g/L of sodium carbonate, at a liquid temperature of 40 ° C and a current density of 10 A/dm ² Perform 10 seconds of processing.

In the pickling treatment of neutralizing the alkaline solution remaining on the surface of the rolled copper foil and removing the copper oxide film, it was immersed in an aqueous solution containing 150 g/L of sulfuric acid at a liquid temperature of 25 ° C for 10 seconds.

Electrolytic treatment using a rolled copper foil as a cathode was performed to form a copper plating layer: a copper plating layer having a thickness of 0.1 μm was formed for a rolled copper foil of 8.0 μm; a copper plating layer having a thickness of 0.4 μm was formed for a rolled copper foil having a thickness of 11.0 μm; for a thickness of 16.5 The rolled copper foil of μm was formed into a copper plating layer having a thickness of 0.7 μm; and the rolled copper foil having a thickness of 17.0 μm was formed into a copper plating layer having a thickness of 1.0 μm. The increase or decrease of the thickness of the copper plating layer while increasing the thickness of the copper-deposited copper foil is in view of mass productivity and production cost, and does not affect the effect of the present embodiment itself.

At this time, in Examples 1 to 32 and some of the comparative examples, the amount of SPS added to the plating solution was changed. Further, in some of the comparative examples, the addition of SPS was not performed. Table 2 below shows the detailed conditions in copper plating.

【Table 2】

Under the conditions of Table 2, copper plating layers having the same degree of flatness were obtained in both the examples and the comparative examples. The surface roughness of the copper plating layer was 0.4 μm to 0.7 μm in terms of ten-point average roughness Rzjis (JIS B0601:2001).

Through the above operations, Examples 1 to 8 and Comparative Examples 1 to 4 in which the rolled copper foil was made of tough copper, Examples 9 to 16 and Comparative Examples 5 to 8 in which the rolled copper foil was made of oxygen-free copper, and the rolled copper foil were added. Examples 17 to 24 and Comparative Examples 9 to 12 of the tough pitch copper of Ag, and the copper-plated rolled copper foils of Examples 25 to 32 and Comparative Examples 13 to 16 in which the copper-free copper was added with Sn-free oxygen-free copper. .

(2) X-ray diffraction according to the 2θ/θ method

The copper plating layer and the rolled copper foil of the rolled copper foil with a copper plating layer which were obtained in the above-mentioned Example and the comparative example were measured by the X-ray diffraction apparatus. The crystal alignment of the rolled copper foil was measured in a state before the copper plating layer was formed. As the X-ray diffraction device, an X-ray diffraction device (model: Ultima IV) manufactured by Rigaku Corporation was used. Table 3 summarizes the measurement conditions.

When the crystal alignment of the copper plating layer is measured, the X-ray output power, the slit, and the like are appropriately changed depending on the thickness of the copper plating layer. Specifically, the thinner the copper plating layer is, the smaller the output power is, and the smaller the slit width and the slit angle are. Here, the range of the measurement angle (2θ) of the {111} plane, the {002} plane, and the {022} plane according to the present invention is sufficient although 40° to 80°, but the measurement is between 40° and 140°. ongoing. In this way, information on the {113} plane, the {133} plane, and the {024} plane of the crystal plane on the high angle side of 2θ and 80° is obtained as a reference. It was confirmed by the measurement on the high angle side that the diffraction peak intensity of the {113} plane, the {133} plane, and the {024} plane was extremely small. From this, it was confirmed that these crystals hardly affected the bending resistance, and it was not considered.

First, the measurement results of representative examples of the four types of rolled copper foils having different materials and total workability are shown in Table 4 below and FIGS. 2 to 5 . Four types of rolled copper foils, that is, rolled copper foil using tough pitch copper, rolled copper foil using oxygen-free copper, rolled copper foil using tough pitch copper added with Ag, and oxygen-free copper to which Sn is added Rolled copper foil. The production conditions of the rolled copper foil were collectively used in the examples and the comparative examples, and the measurement results of all the examples and the comparative examples were specifically realized in the four representative examples.

【Table 4】

Further, the measurement results of the copper plating layers provided in Examples 1 to 32 and Comparative Examples 1 to 16 are shown in Tables 5 to 8 and Figs. 6 to 17 below. That is, Table 5 shows the results of Examples 1 to 8 and Comparative Examples 1 to 4 in which the rolled copper foil was made of tough pitch copper. Further, Table 6 shows the results of Examples 9 to 16 and Comparative Examples 5 to 8 in which the rolled copper foil was made of oxygen-free copper. Further, Table 7 shows the results of Examples 17 to 24 and Comparative Examples 9 to 12 in which the rolled copper foil was made of tough pitch copper to which Ag was added. Further, Table 8 shows the results of Examples 25 to 32 and Comparative Examples 13 to 16 in which the rolled copper foil was made of oxygen-free copper to which Sn was added. In each table, as "the requirements related to the formulas (1) to (6)", the formula (1) is satisfied, and the formula (2), (3) or (4), (5) or (6) is satisfied. In the case of at least one of the states, it is referred to as "satisfaction". Further, in the case where at least one of the following cases is satisfied, it is referred to as "not satisfied": the case where the formula (1) is not satisfied, or the formula (2), (3) or (4), (5) is not satisfied. Or at least one of the states of (6).

According to Tables 5 to 8, the four kinds of copper-based rolled copper foils in the examples are independent of their materials. It is also independent of the thickness and satisfies the formula (1). Further, at least any one of the formulas (2), (3) or (4), (5) or (6) is satisfied.

On the other hand, in the comparative example in which the amount of SPS added during copper plating is small or the copper-clad rolled copper foil in the comparative example which is not added, the material is not related to the material, and is also outside the range of the formula (1) regardless of the thickness. . Further, in the formulas (2) to (5), they are also outside the predetermined range. Here, as is clear from the measurement results of these comparative examples, the requirement (≧15.0) in the above formula (1) is a value having a considerable margin. Therefore, it can be said that it is clear from the equation (1) whether or not the copper plating layer satisfies the formula (1), and whether it is the same crystal structure as the rolled copper foil.

(3) Bending fatigue life test

Next, in order to investigate the bending resistance of each of the rolled copper foil and the rolled copper foil with the copper plating layer, a bending fatigue life test was performed, that is, each rolled copper foil and each rolled copper foil with a copper plating layer were measured until it was broken. The number of times of repeated bending (the number of bending breaks). This experiment was carried out in accordance with the IPC (American Printed Circuits Association) standard using an FPC high-speed bending tester (model SEK-31B2S) manufactured by Shin-Etsu Engineering Co., Ltd. Fig. 18 is a view showing a general sliding bending test apparatus 10 including such an FPC high-speed bending tester.

First, each of the rolled copper foil with the copper plating layer and the rolled copper foil without the copper plating layer was cut into a sample piece 50 having a width of 12.5 mm and a length of 220 mm (220 mm in the rolling direction), following the recrystallization annealing step described above. Recrystallization annealing was performed at 300 ° C for 5 minutes. The conditions mimic an example of the amount of heat actually experienced by the rolled copper foil when it is in close contact with the substrate in the CCL step of the flexible printed circuit board.

Next, as shown in Fig. 18, the sample piece 50 is fixed to the sample fixing plate 11 of the sliding bending test apparatus 10 by screws 12. Then, the sample piece 50 is brought into contact with the vibration transmitting portion 13 and adhered, and the vibration transmitting unit 13 is vibrated in the vertical direction by the oscillation driving body 14, and the vibration is transmitted to the sample piece 50 to carry out a bending fatigue life test. As the measurement conditions of the bending fatigue life, the bending radius 10r was set to 1.5 mm, the stroke 10 s was set to 10 mm, and the frequency was set to 25 Hz. Under these conditions, three pieces of each of the sample pieces 50 were measured, and the average value of the number of times of occurrence of the fracture (the number of bending fractures) was compared.

From the measurement results thus obtained, the measurement results of the monomers of the four kinds of rolled copper foils having different materials and total workability are shown in Table 9 below. The numerical value of the number of bending fractures in Table 9 is the average value of the measurement results of each of the three blocks.

The total degree of processing of each of the four types of rolled copper foils in the final cold rolling step is 90% or more; as a more preferable condition, it is 94% or more; and as a further preferable condition, it is 96% or more. Therefore, it is understood that each of them has a rolled copper foil having excellent bending resistance depending on the height of the total workability.

Further, the measurement results obtained for each of the rolled copper foils with the copper plating layers are shown in Tables 10 to 13 below. That is, Table 10 shows the results of Examples 1 to 8 and Comparative Examples 1 to 4 in which the rolled copper foil was made of tough pitch copper. Further, Table 11 shows the results of Examples 9 to 16 and Comparative Examples 5 to 8 in which the rolled copper foil was made of oxygen-free copper. Further, Table 12 shows the results of Examples 17 to 24 and Comparative Examples 9 to 12 in which the rolled copper foil was made of tough pitch copper to which Ag was added. Further, Table 13 shows the results of Examples 25 to 32 and Comparative Examples 13 to 16 in which the rolled copper foil was made of oxygen-free copper to which Sn was added. Here, the numerical value of the number of bending fractures in each table is the average value of the measurement results of each of the three blocks. Further, the right end of each watch shows the rate of decrease in the number of bending fractures of each of the rolled copper foils with the copper plating layer relative to the number of bending fractures of the rolled copper foil.

Here, the measured values of the rolled copper foil with a copper plating layer having different thicknesses were mixed in each table. The thickness of the rolled copper foil with the copper plating is affected by the number of bending fractures until the fracture, that is, the bending resistance, and therefore it is necessary to pay attention. That is, if the materials are substantially the same, in general, the thicker the thickness, the less the number of bending breaks until breaking. Therefore, in the rolled copper foil with the copper plating layer shown in each table, the thicker the total thickness (total thickness) and the thickness of the rolled copper foil alone, the lower the bending resistance. Here, the thickness of the copper plating layer having a layer thickness thinner than that of the rolled copper foil is not so large in itself. Impact.

In Examples 1 to 32 in which the copper foil was used for the rolled copper foil, the rolled copper foil with the copper plating layer as a whole was significantly improved in bending resistance as compared with the comparative example corresponding thereto. In addition, the degree of improvement in bending resistance of the rolled copper foil with copper plating corresponding to the rolled copper foil of four kinds of copper materials does not depend on the copper material of the rolled copper foil, bending resistance, and copper. The thinner the plating, the better.

In Table 14 below, the measurement results of Examples 1 to 32 and Comparative Examples 1 to 16 were collectively shown in accordance with the thicknesses of the copper plating layer and the rolled copper foil. Further, in Fig. 19, the relationship between the thickness and the number of bending fractures is shown graphically for the four types of rolled copper foils of the copper materials according to Examples 1 to 32, respectively. The horizontal axis of the graph is the thickness (μm) of the rolled copper foil, and the vertical axis is the number of bending fractures (times). Further, the Δ mark on the graph is an example in which tough copper is used for the rolled copper foil. Further, the □ mark is an example in which oxygen-free copper is used for the rolled copper foil. Further, the ◆ mark is an example in which the rolled copper foil is made of tough pitch copper to which Ag is added. Further, the ○ mark is an example in which the rolled copper foil is made of oxygen-free copper to which Sn is added.

According to Table 14, the rate of decrease in the number of bending fractures of the rolled copper foil with the copper plating layer was less than that of the comparative example in any thickness with respect to the number of bending fractures of the rolled copper foil alone.

Further, as is clear from Fig. 19, in general, the thicker the thickness between the copper materials, the lower the number of bending fractures. Here, the rolled copper foil with the copper plating layer according to the examples and the comparative examples has an influence on the number of bending fractures only by the increase in the thickness of the copper plating layer regardless of the crystal structure and characteristics of the copper plating layer. That is, even in the desired copper plating layer, the number of bending fractures is inevitably reduced as compared with the case of rolling the copper foil alone.

Based on the measurement results of the examples, the rate of decrease in the number of times of bending of the rolled copper foil with respect to the rolled copper foil with respect to the rolled copper foil of the embodiment is small, and it can be considered that the thickness is almost only affected by the thickness. Increase the impact of the part. That is, it can be considered that almost no copper plating is produced. Adverse effects caused by crystal structure, etc.

On the other hand, from the measurement results of the comparative examples in which the amount of SPS added is small or not added, the rate of decrease in the number of bending fractures of the rolled copper foil alone is extremely large, and the influence other than the influence of the thickness increase portion is shown. That is, the adverse effect caused by the crystal structure of the copper plating layer or the like.

As described above, it is understood that the formation of the rolled copper foil after the final cold rolling step and before the recrystallization annealing step is different from the alignment of the crystal in which the epitaxial growth occurs, that is, the crystal alignment which is not equivalent to the rolled aggregate structure is formed. The copper plating layer can improve the bending resistance of the rolled copper foil with the copper plating.

Further, it is considered that there is a preferable range among the added amount of SPS used in obtaining such a copper plating layer. At least in the range of the present embodiment, when the amount of SPS added per liter of the plating solution is 20 mg to 150 mg, a sufficient effect can be confirmed, and no difference in effect is observed in the range. Further, when the SPS was 10 mg or less, the effects of the present invention were not confirmed at all. Therefore, it is considered that in the range of more than 10 mg to less than 20 mg, there is a point that the effect of the present invention is exhibited. Further, it is presumed that the effect of the present invention can be continuously obtained even in the case where the SPS exceeds 150 mg. However, from the viewpoint of the mass production property and the cost of the additive, no advantage has been confirmed for the addition of more than 150 mg of SPS.

As described above, the lower limit of the amount of SPS per one liter of plating solution can be set to 20 mg with a clear effect. Further, the upper limit of the amount of SPS per 1 liter of plating solution may be 150 mg.

Here, as described above, the combination of the rolled copper foil and the copper plating layer formed thereon may not be the combination shown in this embodiment. For example, a copper plating layer having a thickness of 1.0 μm may be applied to a rolled copper foil having a thickness of 8.0 μm, or a copper plating layer having a thickness of 0.1 μm may be applied to a rolled copper foil having a thickness of 17.0 μm. In such a configuration, the effects of the present invention as described above can also be obtained.

S10‧‧‧Ingot preparation steps

S20‧‧‧ hot rolling step

S30‧‧‧ Repeat steps

S31‧‧‧ cold rolling step

S32‧‧‧ Annealing step

S40‧‧‧ final cold rolling step

S50‧‧‧ copper plating formation steps

S60‧‧‧ Surface treatment steps

Claims (5)

A rolled copper foil with a copper plating layer, comprising: a rolled copper foil after a final cold rolling step having a plurality of parallel crystal faces on a main surface or a back surface, and a recrystallization annealing step; and forming the calender a copper plating layer having a plurality of parallel crystal faces on a main surface or a surface on at least one side of the main surface of the copper foil or the back surface thereof, on the main surface or the back surface of the interface of the rolled copper foil, in the rolled copper foil Among the plurality of crystal faces, the intensity values of the diffraction peaks obtained by X-ray diffraction performed on the {111} plane, the {002} plane, and the {022} plane in accordance with the 2θ/θ method are each set to I _{R .} {111}, I _R {002}, I _R {022}, the fractions P _R {111}, P _R {002}, P _R {022} of the intensity values of the respective diffraction peaks are set to: P _R {111}=[I _R {111}/(I _R {111}+I _R {002}+I _R {022})]×100, P _R {002}=[I _R {002}/(I _R {111}+I _R {002}+I _R {022})]×100, P _R {022}=[I _R {022}/(I _R {111}+I _R {002}+I _R { 022})]×100, in the plurality of crystal faces of the copper plating layer, obtained by X-ray diffraction performed on the {111} plane, the {002} plane, and the {022} plane according to the 2θ/θ method Diffracting peak Each set intensity value _{I M {111}, I M} {002}, I M {022}, the fraction of the intensity values of each diffraction peak _{P M {111}, P M} {002}, P M {022}Set to: P _M {111}=[I _M {111}/(I _M {111}+I _M {002}+I _M {022})]×100, P _M {002}=[I _M {002}/(I _M {111}+I _M {002}+I _M {022})]×100, P _M {022}=[I _M {022}/(I _M {111}+I _M When {002}+I _M {022})]×100, at least one of the following states is satisfied: P _M {111}≧15.0 (1) satisfying the following formula (1), and further satisfying the following formula: (2) The state of P _M {111}>(P _R {111}+5)...(2); satisfying the following equations (3), (4) P _M {002}<(P _R {002}-10 ) (3), P _M {002}>(P _R {002}+10) (4) The state of any one of the following formulas (5), (6) P _M {022}<( P _R {022}-10) (5), P _M {022}> (P _R {022} + 10) (6) The state of any one of them. The rolled copper foil with a copper plating layer as described in claim 1, wherein at least one of the following formulas (2), (4), and (6) is satisfied: P _M {111}> (P _R {111}+5)...(2),P _M {002}>(P _R {002}+10)...(4),P _M {022}>(P _R {022}+10)...(6 ). The rolled copper foil with copper plating as described in claim 1 or 2, wherein the rolled copper foil is formed of pure copper formed of tough or copper-free copper or tough Copper or oxygen-free copper is a low-concentration copper alloy of a mother phase, and the rolled copper foil adopts a form of a pure copper-type aggregate structure. The rolled copper foil with a copper plating layer as described in any one of Claims 1 to 3, wherein the copper plating layer and the rolled copper foil have a thickness of 1 μm or more and 20 μm or less. The thickness of the copper plating layer is 0.1 μm or more and 1.0 μm or less. A rolled copper foil with a copper plating layer as described in any one of claims 1 to 4, which is a rolled copper foil with a copper plating layer for a flexible printed circuit board.