JP2014139335A - Copper plating layer-clad rolled copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bestow, even if a copper plating layer has been formed, an excellent flexural resistance after a recrystallizing and annealing step.SOLUTION: The provided object is furnished with a rolled copper foil which has undergone a final cold rolling step but has yet to undergo a recrystallizing and annealing step and a copper plating layer formed on at least either of the primary surface of the rolled copper foil and the rear surface thereof and possessing multiple crystal faces mainly having random orientations, whereas crystal grains exhibiting tetrahedral symmetry wherein {022} face diffraction peaks obtained owing to the in-plane rotation of the surface of the copper plating layer at a flap angle α of 45° exist at in-plane rotation angle β intervals of 90°±5° each at the time of a {022} face pole figure measurement rendered with reference to the surface of the copper plating layer exist along the random orientations within the copper plating layer.

Description

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

  A flexible printed circuit (FPC) is thin and excellent in flexibility, and thus has a high degree of freedom in mounting form on an electronic device or the like. For this reason, FPCs are not only for folding parts of foldable mobile phones, but also for moving parts such as digital cameras and printer heads, as well as hard disk drives (HDDs), digital versatile disks (DVDs), and compact disks (DVDs). It is often used for wiring of movable parts of disk related equipment such as CD (Compact Disk). Therefore, the rolled copper foil used as FPC and its wiring material has been required to have high bending properties, that is, excellent bending resistance that can withstand repeated bending.

  The rolled copper foil for FPC is manufactured through processes such as hot rolling and cold rolling, for example. In the subsequent FPC manufacturing process, the rolled copper foil is bonded to an FPC base film (base material) made of a resin such as polyimide by heating or the like via an adhesive or directly. The rolled copper foil on the base material is subjected to surface processing such as etching to become a wiring. The bending resistance of the rolled copper foil is significantly improved in the state after annealing softened by recrystallization than in the hard state after cold rolling that has been rolled and hardened. Thus, for example, in the FPC manufacturing process described above, the rolled copper foil is cut using the hardened rolled copper foil after cold rolling while avoiding deformation such as elongation and wrinkles, and is superimposed on the substrate. Thereafter, the rolled copper foil and the base material are heated together to be combined and heated, whereby the rolled copper foil is recrystallized and annealed to improve the bending resistance.

  On the premise of the manufacturing process of the FPC described above, various studies have been made so far on a rolled copper foil excellent in bending resistance and its manufacturing method. As a result, it has been reported that the flex resistance is improved as the {002} plane ({200} plane) which is a cubic orientation is developed on the surface of the rolled copper foil.

For example, in Patent Document 1, annealing immediately before the final cold rolling is performed under the condition that the average grain size of the recrystallized grains is 5 μm to 20 μm. Further, the rolling degree in the final cold rolling is set to 90% or more. As a result, in a state of being tempered to have a recrystallized structure, the strength of the {200} plane obtained by X-ray diffraction of the rolled surface is I, and the {200} plane obtained by X-ray diffraction of fine powder copper When the intensity is I ₀ , a cubic texture with I / I ₀ > 20 is obtained.

Further, for example, in Patent Document 2, the degree of development of the cube texture before the final cold rolling is increased, and the degree of processing in the final cold rolling is set to 93% or more. Further, by performing recrystallization annealing, a rolled copper foil having a remarkably developed cubic texture with an integral strength of {200} plane of I / I ₀ ≧ 40 is obtained.

  Further, for example, in Patent Document 3, the total work degree in the final cold rolling process is set to 94% or more, and the work degree per pass is controlled to 15% to 50%. Thereby, a predetermined crystal grain orientation state is obtained after recrystallization annealing. That is, the in-plane orientation degree Δβ of the {111} plane with respect to the {200} plane of the rolled plane obtained by X-ray diffraction pole figure measurement is 10 ° or less. Further, the ratio between the normalized diffraction peak intensity [a] of the {200} plane which is a cubic texture in the rolled surface and the normalized diffraction peak intensity [b] of the crystal region in the twin relation of the {200} plane. However, [a] / [b] ≧ 3.

  Thus, in the prior art, by increasing the total degree of work in the final cold rolling process, the cube texture of the rolled copper foil is developed after the recrystallization annealing process, thereby improving the bending resistance.

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

  By the way, in the rolled copper foil for FPC, in order to improve the bonding strength with the base material, for example, after forming a copper plating layer on one side or both sides of the rolled copper foil, roughened particles may be attached.

  However, in the rolled copper foil with a copper plating layer in which the copper plating layer is formed, for example, even a rolled copper foil having improved bending resistance using the techniques of Patent Documents 1 to 3 above is considered to be due to repeated bending. Fatigue fracture may occur. That is, in the rolled copper foil with a copper plating layer, the bending resistance may be deteriorated.

  The objective of this invention is providing the rolled copper foil with a copper plating layer which can be provided with the outstanding bending resistance after a recrystallization annealing process, even if the copper plating layer is formed.

According to a first aspect of the invention,
After the final cold rolling process, the rolled copper foil before the recrystallization annealing process,
A copper plating layer formed on at least one surface of the main surface of the rolled copper foil or its back surface, and having a plurality of crystal faces mainly composed of random orientations, and
In the {022} plane pole figure measurement based on the surface of the copper plating layer, the diffraction peak of the {022} plane obtained by in-plane rotation of the surface of the copper plating layer when the tilt angle α is 45 ° is the in-plane There is provided a rolled copper foil with a copper plating layer in which crystal grains having a four-fold symmetry existing every 90 ° ± 5 ° of the rotation angle β of rotation exist in a random orientation in the copper plating layer.

According to a second aspect of the invention,
The rolled copper foil with a copper plating layer according to the first aspect, in which the rolled copper foil takes the form of a pure copper type texture composed of pure copper or a diluted copper alloy, is provided.

According to a third aspect of the invention,
The rolled copper foil with a copper plating layer according to the first or second aspect, in which the entire thickness of the copper plating layer and the rolled copper foil is 1 μm or more and 20 μm or less.

According to a fourth aspect of the invention,
The rolled copper foil with a copper plating layer according to any one of the first to third aspects, wherein the copper plating layer is thinner than the rolled copper foil.

According to a fifth aspect of the present invention,
The rolled copper foil with a copper plating layer in any one of the 1st-4th aspect which is an object for flexible printed wiring boards is provided.

According to a sixth aspect of the present invention,
After the final cold rolling process, the rolled copper foil before the recrystallization annealing process,
A copper plating layer formed on at least one surface of the main surface of the rolled copper foil or its back surface, and having a plurality of crystal faces mainly composed of random orientations, and
There is provided a rolled copper foil with a copper plating layer in which biaxially oriented {002} plane crystal grains exist in a random orientation in the copper plating layer.

According to a seventh aspect of the present invention,
The biaxially oriented {002} plane crystal grains are
In the {022} plane pole figure measurement, the ratio above the detection limit of the diffraction peak indicating the presence of the biaxially oriented {002} plane is present in the random orientation in the copper plating layer. A rolled copper foil with a copper plating layer is provided.

  ADVANTAGE OF THE INVENTION According to this invention, even if the copper plating layer is formed, the rolled copper foil with a copper plating layer which can be equipped with the outstanding bending resistance after a recrystallization annealing process is provided.

It is a flowchart which shows the manufacturing process of the rolled copper foil with a copper plating layer which concerns on one Embodiment of this invention. It is a figure which shows the outline | summary of the measuring method of the pole figure measurement in the Example and comparative example of this invention. (A) is the pole figure of the copper plating layer of Example 1 of the present invention in the upper stage, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Example 1 of the present invention, (b) The upper row is the pole figure of the rolled copper foil of Comparative Example 5, and the lower row is the measurement result of the pole figure measurement of the rolled copper foil of Comparative Example 5. (A) is the pole figure of the copper plating layer of Comparative Example 1, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Comparative Example 1, and (b) is the upper part of Comparative Example 5. It is a pole figure of rolled copper foil, and the lower stage is a measurement result of pole figure measurement of the rolled copper foil of Comparative Example 5. (A) is the pole figure of the copper plating layer of Comparative Example 3, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Comparative Example 3, and (b) is the upper part of Comparative Example 5. It is a pole figure of rolled copper foil, and the lower stage is a measurement result of pole figure measurement of the rolled copper foil of Comparative Example 5. It is a schematic diagram of the sliding bending test apparatus which measures the bending resistance of the rolled copper foil with a copper plating layer which concerns on the Example and comparative example of this invention. (A) is the pole figure of the copper plating layer of Example 3 of the present invention in the upper stage, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Example 3 of the present invention, (b) The upper row is a pole figure of the rolled copper foil of Comparative Example 11, and the lower row is the measurement result of the pole figure measurement of the rolled copper foil of Comparative Example 11. (A) is the pole figure of the copper plating layer of Comparative Example 7, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Comparative Example 7, and (b) is the upper part of Comparative Example 11. It is a pole figure of rolled copper foil, and a lower stage is a measurement result of pole figure measurement of the rolled copper foil of Comparative Example 11. (A) is the pole figure of the copper plating layer of Comparative Example 9, the lower part is the measurement result of the pole figure measurement of the copper plating layer of Comparative Example 9, and (b) is the upper part of Comparative Example 11. It is a pole figure of rolled copper foil, and a lower stage is a measurement result of pole figure measurement of the rolled copper foil of Comparative Example 11.

<Knowledge obtained by the present inventors>
As described above, for example, in rolled copper foil used as a wiring material for FPC, in order to improve the bonding strength with the base material of FPC, for example, roughened particles may adhere to one or both sides of the rolled copper foil. is there. At this time, in order to uniformly attach the roughened grains, a copper plating layer may be formed on the surface on which the roughened grains of the rolled copper foil are formed, and the surface may be flattened.

  However, in the rolled copper foil in which the copper plating layer is formed, as described in Patent Documents 1 to 3 above, the ratio of the {002} surface after heating is increased, and the rolled copper foil has excellent bending resistance. In some cases, however, the bending resistance deteriorated, such as fatigue fracture. The inventors of the present invention have found that such a rupture occurs from the copper plating layer. It is considered that the breakage generated in the copper plating layer immediately propagates to the rolled copper foil and deteriorates the bending resistance when viewed in the whole rolled copper foil with the copper plating layer.

  Therefore, the present inventors have focused attention on the {002} plane that is slightly present in the crystal structure of the copper plating layer that is mainly in a random orientation. Even in the copper plating layer, it was thought that it would be possible to improve the bending resistance utilizing the characteristics of the {002} plane.

  As a result of earnest research, the present inventors have obtained excellent bending resistance by controlling the state of the {002} plane even if the ratio of the {002} plane included in the random orientation of the copper plating layer is small. I found out that

  The present invention is based on these findings found by the inventors.

<One Embodiment of the Present Invention>
(1) Configuration of Rolled Copper Foil with Copper Plating Layer First, the configuration of the 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 is a rolled copper foil made of oxygen-free copper, tough pitch copper, or a dilute copper alloy having oxygen-free copper or tough pitch copper as a parent phase, and at least one side of the rolled copper foil. A copper plating layer formed on the surface. Moreover, the rolled copper foil with a copper plating layer is configured to have an overall thickness of 1 μm or more and 20 μm or less so as to be used for, for example, an FPC flexible wiring material.

(Outline of rolled copper foil)
The rolled copper foil with which the rolled copper foil with a copper plating layer is provided is configured, for example, in a plate shape having a rolled surface as the main surface. This rolled copper foil has a predetermined thickness by subjecting an ingot made of pure copper such as oxygen-free copper (OFC) or tough pitch copper to a hot rolling process or a cold rolling process, which will be described later. The rolled copper foil after the final cold rolling process and before the recrystallization annealing process. That is, the rolled copper foil according to the present embodiment has a total thickness including the copper plating layer, for example, by a final cold rolling step in which the total workability is 80% or more, preferably 90% or more, more preferably 94% or more. Is configured to have the above-described thickness, for example. After that, as described above, for example, when the recrystallization annealing process is performed on the rolled copper foil with a copper plating layer also serving as a bonding process with the FPC base material, the rolled copper foil tempered for recrystallization Is intended to have excellent flex resistance.

  The oxygen-free copper used as a raw material for the rolled copper foil is a copper material having a purity specified in JIS C1020, H3100, etc. of 99.96% or more. The oxygen content may not be completely zero, and for example, oxygen of about several ppm may be included. Moreover, the tough pitch copper used as the raw material of the rolled copper foil is a copper material having a purity specified in, for example, JIS C1100, H3100, etc. of 99.9% or more. In the case of tough pitch copper, the oxygen content is, for example, about 100 ppm to 600 ppm. The rolled copper foil made of these raw materials is preferably in the form of, for example, a pure copper texture (also referred to as a pure metal texture). Alternatively, as a rolled copper foil, oxygen-free copper or tough pitch copper is added to a small amount of a predetermined additive such as tin (Sn), silver (Ag), boron (B), titanium (Ti) to form a diluted copper alloy, You may use the raw material in which various characteristics, such as property, were adjusted. At this time, it is preferable that the addition amount of the additive is in a range that does not hinder the formation of the crystal orientation form of the pure copper texture by the pure copper of the parent phase.

The total working ratio of the rolled copper foil in the final cold rolling process, the final cold rolling step prior to the workpiece thickness of the (sheet of copper) and T _B, the thickness of the final cold working object after rolling process When _{T a} a is the total working ratio _(%) = represented by _{[(T B -T a) /} T B] × 100. By setting the total workability within the above range, the ratio of the {002} plane after heating in the recrystallization annealing step is increased, and a rolled copper foil that has high bending resistance can be obtained.

(Overview of copper plating layer)
The copper plating layer with which the rolled copper foil with a copper plating layer is provided is formed on the rolling surface as the main surface of the rolled copper foil, or on at least one surface of the back surface, for example, using electrolytic plating. The copper plating layer according to the present embodiment is formed thinner than, for example, a piezoelectric copper foil, and has a thickness of, for example, 0.01 μm or more and 2 μm or less.

  By forming to such a thickness, for example, the surface of the rolled copper foil is flattened by a copper plating layer as a base of roughened grains and a rust preventive layer to be described later, and the roughened grains are uniformly attached, or the rust preventive layer Can be formed uniformly. In addition, by forming the copper plating layer thinner than the rolled copper foil in this way, it becomes easy to improve the bending resistance of the rolled copper foil with a copper plating layer as a whole. In this embodiment, the thinner the copper plating layer, the better.

(Crystal structure of copper plating layer)
The copper plating layer provided in the rolled copper foil with a copper plating layer has a plurality of crystal planes mainly composed of random orientations, that is, random and non-principal orientations. The random orientation of the copper plating layer includes {002} plane crystal grains at a predetermined ratio. At least a part of the {002} plane crystal grains is biaxially oriented.

  The fact that the {002} plane crystal grains are biaxially oriented can be confirmed by {022} plane pole figure (Pole-Figure) measurement using X-ray diffraction. Here, {022} plane pole figure measurement is demonstrated with reference to FIG. Note that the description here is only an outline, and details will be described later.

  As shown in FIG. 2, a sample piece 50 such as a rolled copper foil with a copper plating layer is disposed so as to be rotatable around three scanning axes of the θ axis, the α axis, and the β axis. In the {022} plane pole figure measurement, the sample piece 50 is rotated around the α axis, and diffracted X-rays are detected in the manner of the 2θ / θ method with respect to a predetermined tilt angle α within a range of 15 ° to 90 °. That is, the sample piece 50 is rotated about the θ axis, and incident X-rays are incident on the sample piece 50 at an angle θ. Further, diffracted X-rays diffracted at an angle 2θ with respect to the incident direction of incident X-rays are detected. At this time, at the predetermined tilt angle α, while maintaining the angle α, the sample piece 50 described above is rotated around the β axis, and the in-plane rotation angle β is changed within a range of 0 ° to 360 °. Measurement is performed to obtain diffraction peaks on the {022} plane of the copper crystal at each rotation angle β.

  In order to examine the orientation of the crystal grains on the {002} plane, the tilt angle α is set to 45 ° in the {022} plane pole figure measurement based on the surface of such a copper plating layer. A diffraction peak of the {022} plane is obtained by in-plane rotation of the surface of the copper plating layer when the tilt angle α is 45 °. If the biaxially oriented {002} plane crystal grains are present in a random orientation in the copper plating layer, the diffraction peak of the {022} plane obtained exhibits fourfold symmetry. That is, a diffraction peak of the {022} plane appears every 90 ° ± 5 ° of the in-plane rotation angle β when the tilt angle α is 45 °. Specifically, when the rotation angle β in the rolling direction of the rolled copper foil with a copper plating layer is 0 °, the centers of the four-fold symmetric diffraction peaks are β = 0 ° ± 5 °, 90 ° ± 5 °, 180 ° ± 5 ° and 270 ° ± 5 °.

  In addition, if the {022} plane diffraction peak exhibiting 4-fold symmetry is recognized in the above-described {022} plane pole figure measurement, the ratio of the crystal grains of the {002} plane that is biaxially oriented is not particularly limited. In other words, the crystal grains of the {002} plane that are biaxially oriented have a degree of detection of the diffraction peak of the {022} plane that exhibits fourfold symmetry, that is, in the copper plating layer at a ratio that exceeds the detection limit. If present, the configuration of the present embodiment is satisfied.

(Action of crystal structure)
As described above, the rolled copper foil in the present embodiment has a high ratio of the {002} plane after the recrystallization annealing step and has excellent bending resistance.

  On the other hand, in the crystal structure of the copper plating layer, at least a part of the crystal grains on the {002} plane is biaxially oriented in the state after the final cold rolling process and before the recrystallization annealing process. Thereby, the outstanding bending resistance is obtained also in a copper plating layer.

  As described above, the present inventors considered that the bending resistance can be obtained even in the copper plating layer by utilizing the characteristics of the crystal grains of the {002} plane. However, in the copper plating layer, it is difficult to form the {002} plane predominantly like the surface of the rolled copper foil. The copper plating layer is epitaxially grown on the base, here the final cold rolling process, and before the recrystallization annealing process, and the crystal orientation before the recrystallization annealing process of the rolled copper foil, that is, the crystal growth , {002} plane is considered to be in substantially the same state as the previous orientation. Alternatively, it is considered that the epitaxial growth does not occur and the orientation is almost completely random and non-principle (random orientation).

  In addition, it is difficult to accumulate large processing strains in the copper plating layer as in the rolled copper foil, and it is considered that the crystal orientation hardly changes in the degree of heat treatment, for example, in the FPC manufacturing process described above. That is, the crystal orientation of the copper plating layer is determined when the copper plating layer is formed or at least when the production of the rolled copper foil with the copper plating layer is completed. This is because the rolled copper foil with a copper plating layer according to the prior art has a boundary line in which the crystal grains of the copper plating layer and the crystal grains of the rolled copper foil are independent and discontinuous, and this state is a recrystallization annealing. It is clear from the fact that it will be maintained almost as it is later. In the copper plating layer, recrystallization may be mixed before the heat treatment, that is, at room temperature, but as described above, mainly random orientation crystal grains are dominant.

  Therefore, the present inventors have focused on the {002} plane that exists slightly in the crystal structure of the copper plating layer that is mainly in a random orientation. Even if the ratio of the {002} plane in the copper plating layer cannot be remarkably increased, the bending resistance is improved by orienting the {002} plane biaxially instead of uniaxially. I found it. The present inventors believe that the biaxially oriented {002} plane contributes to the improvement of bending resistance in some form. The present inventors also speculate that the biaxially oriented {002} plane may function as a nucleus for crystal growth during recrystallization annealing.

(Other configurations of rolled copper foil with copper plating layer)
On the copper plating layer of the rolled copper foil with a copper plating layer, for example, a roughened copper plating layer, a capsule copper plating layer, and a rust prevention layer may be provided in this order. The roughened copper plating layer includes roughened grains. The roughened grains are, for example, copper (Cu) alone or at least one of iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), zinc (Zn), and the like. It is a metal particle having a diameter of about 1 μm including at least types. The capsule copper plating layer is a so-called covering plating layer that grows roughened grains into bump-shaped protrusions. The anticorrosive layer has a laminated structure in which, for example, a nickel plating layer, a zinc plating layer, a trivalent chromium chemical conversion treatment layer, and a silane coupling layer are formed in this order.

(2) Manufacturing method of rolled copper foil with copper plating layer The present inventors have a copper plating layer of this embodiment in which at least a part of crystal grains on the {002} plane of the copper plating layer is biaxially oriented. In order to obtain a rolled copper foil, intensive research was conducted.

  Specifically, an agent that promotes biaxial orientation of crystal grains on the {002} plane of the copper plating layer (hereinafter also referred to as an orientation adjusting agent) is added to the plating bath when forming the copper plating layer. Various additives were tried, considering that it was sufficient. As a result, the function of biaxially orienting the crystal grains on the {002} plane of the copper plating layer was recognized as a predetermined additive used in electrolytic plating or the like. In other words, the present inventors have found a new effect as an alignment adjusting agent in a predetermined additive which has been used as a brightener or a plating accelerator.

  Next, the manufacturing method of the rolled copper foil with a copper plating layer based on one Embodiment of this invention based on the above knowledge is demonstrated using FIG. FIG. 1 is a flowchart showing a manufacturing process of a rolled copper foil with a copper plating layer according to the present embodiment.

(Ingot preparation step S10)
As shown in FIG. 1, first, a rolled copper foil portion of a rolled copper foil with a copper plating layer is manufactured.

  That is, an ingot is prepared by casting 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. Oxygen-free copper or tough pitch copper used as a raw material may be a dilute copper alloy to which a predetermined additive is added in order to adjust various properties of the rolled copper foil.

  Various characteristics of the rolled copper foil that can be adjusted with the additive include, for example, heat resistance. As described above, in the rolled copper foil for FPC, the recrystallization annealing step for obtaining high bending resistance is performed, for example, also as a bonding step with the FPC base material. The heating temperature at the time of bonding is set in accordance with, for example, the curing temperature of a substrate made of an FPC resin or the like, the curing temperature of an adhesive to be used, and the range of temperature conditions is wide and diverse. In order to adjust the softening temperature of the rolled copper foil to the heating temperature set in this way, an additive capable of adjusting the heat resistance of the rolled copper foil may be appropriately added.

  As an ingot used in the present embodiment, an ingot having no additive added, and an ingot added with several kinds of additives are exemplified in Table 1 below.

  Moreover, as a representative example of the additive which raises or lowers the heat resistance as the additive shown in Table 1 and other additives, for example, tin (Sn), silver (Ag), boron (B) of about 10 ppm to 2000 ppm , Niobium (Nb), titanium (Ti), nickel (Ni), zirconium (Zr), vanadium (V), manganese (Mn), hafnium (Hf), tantalum (Ta), and calcium (Ca) There are examples of adding one or more elements. Alternatively, there is an example in which Ag is added as the first additive element and any one or more of the above-described 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), antimony (Sb), gold (Au) ) Etc. can also be added in small amounts.

  Note that the composition of the ingot is maintained substantially as it is in the rolled copper foil after the final cold rolling step S40 described later, and when an additive is added to the ingot, the ingot and the rolled copper foil Have substantially the same additive concentration.

  Moreover, the temperature conditions in the below-mentioned annealing process S32 are suitably changed according to the heat resistance by a copper material or an additive. However, the change of the temperature condition of the said copper material, an additive, and annealing process S32 according to this has little influence with respect to the effect of this embodiment.

(Hot rolling process S20)
Next, the prepared ingot is hot-rolled to obtain a plate material having a thickness smaller than a predetermined thickness after casting.

(Repetition step S30)
Subsequently, a repeating step S30 is performed in which the cold rolling step S31 and the annealing step S32 are repeatedly performed a predetermined number of times. That is, work hardening is relieved by subjecting the plate material that has been cold-rolled and work hardened to an annealing treatment to anneal the plate material. By repeating this a predetermined number of times, a copper strip called “dough” is obtained. When an additive for adjusting heat resistance is added to the copper material, the temperature condition of the annealing treatment is appropriately changed according to the heat resistance of the copper material.

  In addition, in the repetition process S30, the annealing process S32 in the middle of the repetition is referred to as an “intermediate annealing process”. Further, the annealing step S32 performed at the end of the repetition, that is, immediately before the final cold rolling step S40 described later is referred to as a “final annealing step” or a “dough annealing step”. In the dough annealing process, the above copper strip (fabric) is subjected to dough annealing to obtain an annealed dough. Also in the dough annealing step, the temperature condition is appropriately changed according to the heat resistance of the copper material. At this time, the dough annealing step is preferably performed under a temperature condition that can sufficiently relieve the processing strain caused by each of the above steps, for example, a temperature condition substantially equivalent to a complete annealing treatment.

(Final cold rolling process S40)
Next, the final cold rolling step S40 is performed. The final cold rolling is also called finish cold rolling, and the cold rolling to be finished is applied to the annealed fabric a plurality of times to form a thin copper foil. At this time, the total work degree in the final cold rolling step S40 is set to 80% or more, preferably 90% or more, more preferably 94% or more so that a rolled copper foil having high bending resistance can be obtained. Thereby, it becomes a rolled copper foil in which excellent bending resistance is easily obtained after the recrystallization annealing step.

Moreover, it is preferable to gradually reduce the degree of processing per one (one pass) as the annealed dough becomes thinner each time cold rolling is repeated a plurality of times. Here, the degree of processing per pass follows the above-described example of the total degree of processing, and the thickness of the workpiece before rolling of the nth pass is T _Bn, and the thickness of the workpiece after rolling is T B _Assuming that _An is a degree of processing per pass (%) = [(T _Bn −T _An ) / T _Bn ] × 100.

  At the time of rolling, an object to be processed such as annealed dough is reduced in thickness by, for example, being drawn into a gap between a pair of rolls facing each other and drawn to the opposite side. The speed of the workpiece is slower than the rotation speed of the roll on the entrance side before being drawn into the roll, and faster than the rotation speed of the roll on the exit side after being drawn out of the roll. Accordingly, the workpiece is subjected to compressive stress on the entrance side and tensile stress on the exit side. In order to thinly process a workpiece, compressive stress> tensile stress must be satisfied. As described above, for example, by adjusting the degree of processing per pass, it is possible to adjust the ratio of each stress component (compression component and tensile component) on the assumption that compression stress> tensile stress.

  In the final cold rolling step S40, it is preferable to control the position of the neutral point described below to move toward the outlet side of the roll every time cold rolling is repeated a plurality of times. That is, as described above, the speed of the workpiece whose magnitude relationship is reversed between the inlet side and the outlet side with respect to the rotational speed of the roll is the rotational speed of the roll at some position between the inlet side and the outlet side. Is equal to A position where both speeds are equal is called a neutral point, and the pressure applied to the workpiece is maximized at the neutral point.

  The position of the neutral point can be controlled by adjusting a combination of forward tension, backward tension, rolling speed (roll rotational speed), roll diameter, degree of processing, rolling load, and the like. That is, the ratio between the compressive stress and the tensile stress can be adjusted also by controlling the position of the neutral point.

  Thus, by applying the final cold rolling step S40 while adjusting the stress balance between the compressive stress and the tensile stress by controlling the degree of processing in each pass, the position control of the neutral point, etc., the compressive stress and the tensile stress are applied. The stress balance with the stress can be adjusted as appropriate.

  The rolled copper foil in the rolled copper foil with a copper plating layer concerning this embodiment is manufactured by the above.

(Copper plating layer forming step S50)
Subsequently, a copper plating layer is formed on the rolled surface of the rolled copper foil or on at least one surface of the back surface thereof.

In forming the copper plating layer, the rolled copper foil is preliminarily immersed in a degreasing bath and an acid cleaning bath in advance to clean the surface of the rolled copper foil. That is, in the degreasing bath, cathode electrolytic degreasing is performed using an alkaline solution such as a sodium hydroxide (NaOH) aqueous solution. In the subsequent acid cleaning bath, for example, acid cleaning is performed on the surface of the rolled copper foil using an acidic solution such as a sulfuric acid (H ₂ SO ₄ ) aqueous solution or a copper etching solution to neutralize the alkali solution remaining on the surface, The copper oxide film (CuO) formed on the surface is removed.

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

  At this time, it is preferable to make the plating current density smaller than the limit current density. Thereby, it is suppressed that an unevenness | corrugation arises on the surface, and a flatter copper plating layer is obtained. However, productivity is improved as the plating current density is higher. Therefore, the plating current density is preferably set as high as possible within a range smaller than the limit current density. The standard of plating conditions is illustrated below. However, the following conditions are merely examples of plating conditions and are not limited thereto. The liquid composition such as a copper sulfate-sulfuric acid bath, liquid temperature, and electrolysis conditions can be selected from a wide range.

Copper sulfate pentahydrate: 20 g / L to 300 g / L
Sulfuric acid: 10 g / L to 200 g / L
Liquid temperature: 15 ° C to 50 ° C
Plating current density: 1 A / dm ^{2 to} 30 A / dm ² (less than the limit current density)
Plating time: 1 second to 20 seconds

  Further, in the copper sulfate-sulfuric acid bath, as additives, for example, disodium bis (3-sulfopropyl) disulfide (hereinafter also referred to as SPS) or 3-mercapto-1-propanesulfonic acid (hereinafter also referred to as MPS). A compound having a mercapto (-SH) group such as is added. Moreover, the chemical | medical solution which has polyethyleneglycol (PEG: Poly-Ethylene Glycol) as a main component is added as another additive.

  Immerse the cleaned copper foil in an acidic copper plating bath with such an additive, apply electrolytic plating with the rolled copper foil as the cathode, and apply copper plating to one or both sides of the rolled copper foil. Form a layer. Thereby, a copper plating layer having {002} -plane crystal grains at least partially biaxially oriented is obtained.

  In this way, the present inventors added copper and other additives such as SPS, MPS, and PEG, so that at least a part of the random orientation of the copper plating layer was biaxially oriented {002} plane It was found that the crystal grains were easily obtained. The present inventors presume that at least one of these additives, or a plurality of these additives, or a predetermined combination thereof, works as an alignment regulator that controls the orientation of crystal grains in the {002} plane. . Such effects, uses and usages of SPS, MPS, PEG, etc. found by the present inventors are completely different from conventional effects, uses and usages of these compounds as brighteners and surfactants. It is new.

(Surface treatment step S60)
The surface of the copper plating layer formed as described above is subjected to a predetermined treatment, and the rolled copper foil with a copper plating layer according to this embodiment is manufactured.

  Here, as the predetermined surface treatment, as shown below, for example, a roughened copper plating layer, a capsule copper plating layer, and a rust prevention layer may be sequentially formed on the copper plating layer. However, these processes described below may not be performed.

  First, the example which forms a roughening copper plating layer in a copper plating layer is demonstrated.

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

  Further, in roughened copper plating, electrolysis is performed with a copper plating layer as a base at a high current density equal to or higher than a limit current density, that is, a current density that is so-called burn plating. However, at this time, the liquid composition such as a copper sulfate-sulfuric acid bath, the liquid temperature, and the electrolysis conditions can be selected from a wide range. As a result, electrodeposits and deposits adhere to the copper plating layer, which further enlarges to obtain roughened grains having a diameter of, for example, about 1 μm.

  Then, the example which forms a capsule copper plating layer is demonstrated.

  That is, the roughened grains of the roughened copper plating layer are plated with a current less than the limit current density of the plating bath described above to grow the roughened grains into bump-shaped copper grains. However, when it is desired to keep the coarse grains fine, it is not necessary to form the capsule copper plating layer. At this time, the liquid composition such as a copper sulfate-sulfuric acid bath, liquid temperature, and electrolysis conditions can be selected from a wide range. At this time, an organic additive may be added to the plating bath.

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

  The rust preventive layer is also referred to as a post-treatment plated layer, and thereby sufficient rust preventive performance can be obtained. First, a nickel plating layer or a nickel alloy plating layer is formed to suppress copper diffusion. Subsequently, a zinc plating layer or a zinc alloy plating layer is formed to improve heat resistance. Next, a trivalent chromium chemical conversion treatment layer is formed using a trivalent chromium type reactive chromate solution or the like. Thereafter, for example, a silane coupling layer is formed as a chemical conversion coating, and adhesion with the FPC substrate is improved.

  Thus, the surface treatment of the copper plating layer is completed.

(3) Manufacturing method of flexible printed wiring board Next, the manufacturing method of the flexible printed wiring board (FPC) using the rolled copper foil with a copper plating layer which concerns on one Embodiment of this invention is demonstrated.

(Recrystallization annealing process (CCL process))
First, the rolled copper foil with a copper plating layer according to the present embodiment is cut into a predetermined size, and bonded to an FPC base material made of a resin such as polyimide to form a CCL (Copper Clad Laminate). At this time, either a method of forming a three-layer material CCL that is bonded using an adhesive or a method of forming a two-layer material CCL that is directly bonded without using an adhesive may be used. In the case of using an adhesive, the surface and base having a copper plating layer of the rolled copper foil with a copper plating layer and roughened grains adhering to it by curing the above-mentioned adhesive such as a silane coupling agent by heat treatment. The material is closely adhered and combined. When the adhesive is not used, the surface of the rolled copper foil with a copper plating layer and the surface having roughened grains attached thereto is directly adhered to the substrate by heating and pressing. The heating temperature and time can be appropriately selected according to the curing temperature of the adhesive and the base material, and can be set to 1 to 120 minutes at a temperature of 150 to 400 ° C., for example.

  As above-mentioned, the heat resistance of the rolled copper foil with which the rolled copper foil with a copper plating layer is equipped is adjusted according to the heating temperature at this time. Therefore, the rolled copper foil in the state of work hardening in the final cold rolling step S40 is softened by the heating and tempered to recrystallization. That is, the CCL process of bonding the rolled copper foil with the copper plating layer to the base material also serves as a recrystallization annealing process for the rolled copper foil of the rolled copper foil with the copper plating layer.

  Thus, in the process until the CCL process also serves as the recrystallization annealing process and the rolled copper foil with the copper plating layer is bonded to the base material, the rolled copper foil is work-hardened after the final cold rolling process S40. Thus, the rolled copper foil with a copper plating layer can be handled, and deformation such as elongation, wrinkle, and fold can be made difficult to occur when the rolled copper foil with a copper plating layer is bonded to a substrate.

  The softening of the rolled copper foil as described above indicates that a tempered rolled copper foil, that is, a rolled copper foil having a recrystallized structure, was obtained by the recrystallization annealing process. Specifically, the ratio of the {002} plane is increased, and a rolled copper foil having excellent bending resistance can be obtained.

  On the other hand, in order to change the crystal orientation of the copper plating layer, the heat energy is too small under the heat treatment conditions in the CCL process. For this reason, the crystal structure of the copper plating layer is maintained in the state immediately after the copper plating layer is formed without substantially changing after the recrystallization annealing step. However, as described above, in this embodiment, after the copper plating layer is formed, at least a part of the {002} plane of the copper plating layer is biaxially oriented. Thereby, the copper plating layer has excellent bending resistance regardless of before and after the recrystallization annealing step.

(Surface machining process)
Next, a surface processing step is performed on the rolled copper foil with a copper plating layer bonded to the base material. In the surface processing step, a wiring forming step for forming a copper wiring or the like on the rolled copper foil with a copper plating layer using a technique such as etching, and a plating process for improving the connection reliability between the copper wiring and other electronic members. And a protective film forming process for forming a protective film such as a solder resist so as to cover a part of the copper wiring in order to protect the copper wiring and the like.

  By the above, FPC using the rolled copper foil with a copper plating layer concerning this embodiment is manufactured.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

  For example, in the above-described embodiment, Sn, Ag, B, and the like are mainly used as the additive for adjusting the heat resistance of the rolled copper foil included in the rolled copper foil with a copper plating layer. , Ag, B and the above-mentioned representative examples. Moreover, the various characteristics that can be adjusted by the additive are not limited to heat resistance, and the additive may be appropriately selected according to the various characteristics that require adjustment.

  In the above-described embodiment, the CCL process in the FPC manufacturing process also serves as a recrystallization annealing process for the rolled copper foil. However, the recrystallization annealing process may be performed as a separate process from the CCL process.

  Moreover, in the above-mentioned embodiment, although the rolled copper foil with a copper plating layer was used for FPC use, the use of the rolled copper foil with a copper plating layer is not restricted to this, For example, the negative electrode of a lithium ion secondary battery It can also be used for current collector copper foil and other applications that require bending resistance. Also, the thickness of the rolled copper foil with a copper plating layer may be ultra-thin of 10 μm or less, or over 20 μm, depending on various uses including FPC.

  Moreover, in the above-mentioned embodiment, although the copper plating layer was made thinner than a rolled copper foil, it is not restricted to this. Even if the copper plating layer is thicker than the rolled copper foil, for example, the predetermined effect of the present invention that improves the bending resistance of the rolled copper foil with a copper plating layer as a whole can be obtained.

  Moreover, in the above-mentioned embodiment, although rolled copper foil assumed the form of the pure copper type | mold texture, it is not restricted to this. For example, when used for purposes other than FPC, it may take the form of an alloy-type texture.

  Moreover, in the above-mentioned embodiment, although the crystal structure of the copper plating layer mainly has a random orientation, it may not be completely random. For example, it may be a quasi-random orientation in which the crystal orientation is somewhat unevenly distributed or oriented. That is, a biaxially oriented {002} plane may exist in the quasi-random orientation, and even in such a case, the effect of improving the bending resistance can be obtained by the biaxially oriented {002} plane. . That is, “random orientation” in the present specification means “random orientation in a broad sense” including “quasi-random orientation”.

  In addition, such a quasi-random orientation is a copper plating with respect to a {022} plane or the like that is a rolling crystal orientation oriented on the rolling surface of the rolled copper foil after the final cold rolling step and before the recrystallization annealing step. This is seen when the layer grows more or less epitaxially. Alternatively, the quasi-random orientation is seen regardless of the crystal orientation of the rolled copper foil, that is, when the {022} plane is unevenly distributed without epitaxial growth. Although it is difficult to distinguish between the two, the effect obtained by the biaxially oriented {002} plane remains unchanged.

  Moreover, in the above-mentioned embodiment, although the roughening copper plating layer, the capsule copper plating layer, and the antirust layer were provided on the copper plating layer, the combination of these layers is arbitrary. For example, when making coarse grains small, it is not necessary to provide capsule copper plating. Moreover, you may provide a rust prevention layer directly on a copper plating layer, without providing a roughening copper plating layer and a capsule copper plating layer. Also, depending on the application to which the rolled copper foil with a copper plating layer is applied, that is, in applications other than the FPC application, it is not necessary to consider the adhesiveness to the substrate in the first place, and all configurations on the copper plating layer are omitted. It is also possible to do.

  Further, in the above-described embodiment, the total degree of work in the final cold rolling step S40 is set to 80% or more, and excellent bending resistance is obtained in the rolled copper foil. Even if the degree of processing is less than 80%, for example, the predetermined effect of the copper plating layer with improved bending resistance can be obtained independently. Therefore, when it is sufficient that a certain degree of bending resistance is obtained, the total processing degree of the rolled copper foil can be kept low, for example, less than 80%, or less than 70%, and the load in the manufacturing process can be reduced. it can.

  Moreover, in the above-mentioned embodiment, as a manufacturing method of the rolled copper foil with a copper plating layer in which at least a part of crystal grains on the {002} plane of the copper plating layer is biaxially oriented, SPS, MPS, PEG, etc. A predetermined effect was found in electrolytic plating using an additive. However, in addition to these, other additives having a function as an alignment regulator may be used. Further, the orientation of the {002} plane of the copper plating layer may be controlled by another copper plating layer forming step different from the above or a recrystallization annealing step.

  The main point of the present invention is that at least a part of the {002} plane of the copper plating layer of the rolled copper foil with a copper plating layer is biaxially oriented, and thereby excellent bending resistance in the copper plating layer. It is in the point that it is obtained.

  In addition, in order to show the effect of this invention, not all the processes mentioned above are necessarily essential. The various conditions given in the above-described embodiment and examples described later are merely examples, and can be changed as appropriate.

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

(1) Rolled copper foil with a copper plating layer using oxygen-free copper First, rolled copper foil with a copper plating layer according to Examples 1 and 2 and Comparative Examples 1 to 4 using oxygen-free copper, and Comparative Example 5, A rolled copper foil without a copper plating layer according to No. 6 was produced, and various evaluations were performed for each.

(Production of rolled copper foil with copper plating layer)
First, the rolled copper foil with a copper plating layer according to Examples 1 and 2 and Comparative Examples 1 to 4 and the rolled copper foil without a copper plating layer according to Comparative Examples 5 and 6 were manufactured as follows.

  Using oxygen-free copper having a purity of 99.99%, two oxygen-free copper ingots were produced by the same procedure and method as in the above embodiment. Next, a plate material having a thickness of 8 mm was obtained in the hot rolling step by the same procedure and method as in the above embodiment. A dough annealing process was performed on a copper strip (fabric) obtained by repeatedly performing a cold rolling process and an intermediate annealing process on the plate material to obtain an annealed dough.

  In the intermediate annealing step, the plate material was held at a temperature of 700 ° C. to 800 ° C. for about 1 minute to 2 minutes. In the dough annealing step, the dough was held at a temperature of about 700 ° C. for about 1 minute. Here, the temperature conditions of each annealing process were matched with the heat resistance of the copper material made of oxygen-free copper. In addition, each annealing condition differs with respect to the same copper material because heat resistance changes according to the thickness of copper material. Specifically, the temperature can be lowered when the copper material is thin.

  Next, the final cold rolling process was performed. At this time, for some annealed fabrics, the rolled copper foil according to Example 1 and Comparative Examples 1, 3, and 5 having a total workability of 80% and a thickness of 19.0 μm was manufactured. For other annealed fabrics, rolled copper foils according to Example 2 and Comparative Examples 2, 4 and 6 having a total workability of 95% and a thickness of 11.0 μm were manufactured.

  Subsequently, a copper plating layer was formed on the surface of the rolled copper foil excluding Comparative Examples 5 and 6 as follows.

First, electrolytic degreasing for cleaning the surface of the rolled copper foil was performed. At this time, the treatment was carried out for 10 seconds 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 .

  Subsequently, a pickling treatment was performed to neutralize the alkaline solution remaining on the surface of the rolled copper foil and remove the copper oxide film. At this time, it was immersed for 10 seconds at a liquid temperature of 25 ° C. in an aqueous solution containing 150 g / L of sulfuric acid.

  Next, electrolytic treatment using a rolled copper foil as a cathode was performed to form a copper plating layer on the rolled surface of the rolled copper foil. At this time, all the copper plating layers had a thickness of 1.0 μm. Table 2 shows the plating conditions for each rolled copper foil.

  Under the conditions shown in Table 2, a copper plating layer having the same level of flatness was obtained. The surface roughness of the copper plating layer was 0.5 μm to 0.8 μm in terms of ten-point average roughness Rzjis (JIS B0601: 2001).

({022} face pole figure measurement)
About the rolled copper foil with the copper plating layer according to Examples 1 and 2 and Comparative Examples 1 to 4 obtained as described above and the copper plating layer according to Comparative Examples 5 and 6, the copper plating layer and The crystal orientation of the rolled copper foil was measured with an X-ray diffractometer. As the X-ray diffractometer, an X-ray diffractometer (Model: Ultimate IV) manufactured by Rigaku Corporation was used. Moreover, when measuring the crystal orientation of a copper plating layer, it was set as the output which the X-ray irradiated to the surface of a copper plating layer does not permeate | transmit a rolled copper foil through a copper plating layer. Specifically, the X-ray output was set to 0.8 kW (40 kV × 20 mA) after confirming that the X-ray did not pass through the rolled copper foil.

  Pole-Figure measurement using X-ray diffraction includes a reflection method in which the tilt angle α is in the range of 15 ° to 90 ° and a transmission method in which the tilt angle α is in the range of 0 ° to 15 °. 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, the sample piece 50 of the rolled copper foil or the rolled copper foil with the copper plating layer is arranged so as to be rotatable around the three scanning axes of the θ axis, the α axis, and the β axis as described above. To do. These three scanning axes are generally called a sample axis, a tilt axis, and an in-plane rotation axis, respectively. For the measurement of X-ray diffraction in the present embodiment, X-rays (Cu Kα rays) generated from a copper (Cu) tube are used.

  In the pole figure measurement, the scanning angle of the detector is fixed to the 2θ value of the {hkl} plane of interest, and α-axis scanning is performed in steps with respect to this 2θ value. At this time, the sample piece 50 is subjected to β-axis scanning for each α value, that is, in-plane rotation (rotation) from 0 ° to 360 ° is performed. As a result, how much the {hkl} surface of interest is inclined with respect to the direction perpendicular to the surface to be measured, such as the surface of the copper plating layer or the rolled surface of the rolled copper foil, and the in-plane rotation direction (rotating and shifting). And the overall formation state of the crystal orientation can be grasped.

  In this example, in order to investigate the orientation of the {002} plane, in-plane orientation measurement (symmetry measurement) using the characteristics of the pole figure measurement as described above was performed.

  That is, in the in-plane orientation measurement, the tilt angle α defined as follows is used for measurement. That is, the tilt angle α in the direction perpendicular to the sample piece 50 (β-axis direction) is defined as 90 °. Further, α ′ is an angle formed by a {h′k′l ′} plane, which is a crystal plane geometrically corresponding to the {hkl} plane, which is the crystal plane of interest, and the {hkl} plane. At this time, the tilt angle α is defined as 90−α ′.

  Under such a definition, the α axis is scanned so that the tilt angle α becomes “90−α ′”, that is, the sample piece 50 is tilted, and the scanning angle of the detector is set to {h′k′l ′}. After fixing to the 2θ value of the surface, the sample piece 50 is β-axis scanned with respect to this 2θ value.

  In this measurement, it is possible to evaluate to what extent the target {hkl} plane rotates within the measurement target plane. That is, for example, when the {002} plane is biaxially oriented, 4 indicates biaxial orientation by measuring the in-plane orientation of the {022} plane that is inclined by 45 ° with respect to the {002} plane. A symmetric diffraction peak is detected.

  More specifically, the presence of a biaxially oriented {002} plane is shown by the following. That is, in the {022} pole figure measurement based on the surface of the copper plating layer, the diffraction peak of the {022} plane obtained by in-plane rotation of the surface of the copper plating layer when the tilt angle α is 45 ° is in-plane rotation. The crystal grains having the 4-fold symmetry existing every 90 ° ± 5 ° of the rotation angle β are present in the random orientation in the copper plating layer. This makes it possible to indirectly evaluate the presence of the biaxially oriented {002} plane in the copper plating layer.

  The results of the pole figure measurement of Example 1 and Comparative Examples 1, 3, and 5 are shown in FIGS.

  3 (a), 4 (a), and 5 (a) are measurement results of the copper plating layers of Example 1 and Comparative Examples 1 and 3. FIG. Moreover, the measurement result of the rolled copper foil of the comparative example 5 is shown by FIG.3 (b), FIG.4 (b), FIG.5 (b) for the comparison. Moreover, the upper part of each figure is a pole figure, and the lower part is the spectrum of the diffraction peak of the pole figure measurement. The horizontal axis is the rotation angle β (°), and the vertical axis is the diffraction intensity (arbitrary unit).

  As shown in FIG. 3A, in the copper plating layer of Example 1, fourfold symmetry is observed in the diffraction peak. In addition, the region other than the diffraction peak showing the fourfold symmetry shows a random orientation. Therefore, it can be seen that the crystal structure of the copper plating layer of Example 1 is a state in which only the {002} plane is biaxially oriented in a crystal mainly having a random orientation. In Example 2, similar results were obtained.

  Further, when viewing the upper part of FIG. 3A, some uneven distribution is recognized near the center of the pole figure, that is, when the tilt angle is around 90 °. That is, the random orientation in the copper plating layer of Example 1 is considered to be a quasi-random orientation. Also in this case, the effect of the {002} plane biaxially oriented is exhibited.

  Further, as shown in FIG. 4A, in the copper plating layer of Comparative Example 1, no four-fold symmetry is observed in the diffraction peak. In Comparative Example 2, similar results were obtained.

  Further, as shown in FIG. 5 (a), the copper plating layer of Comparative Example 3 has a diffraction peak substantially similar to the diffraction peak of the underlying rolled copper foil shown in FIG. 5 (b). Obtained. From this, it can be seen that in Comparative Example 3, the copper plating layer was epitaxially grown following the crystal structure of the rolled copper foil. In addition, no four-fold symmetry is observed in the diffraction peak. In Comparative Example 4, similar results were obtained.

  The difference between the above Examples and Comparative Examples may be influenced by whether or not a predetermined amount or more of various additives are added to the plating bath during the formation of the copper plating layer.

(Bending fatigue life test)
Next, in order to examine the bending resistance of each rolled copper foil and each rolled copper foil with a copper plating layer, the number of repeated bendings (number of bendings) until each rolled copper foil and each rolled copper foil with a copper plating layer break A bending fatigue life test was performed. Such a test was performed using an FPC high-speed bending tester (model: SEK-31B2S) manufactured by Shin-Etsu Engineering Co., Ltd. in accordance with the IPC (American Printed Circuit Industry Association) standard. FIG. 6 shows a schematic diagram of a general sliding bending test apparatus 10 including such an FPC high-speed bending tester.

  First, the above-described recrystallization annealing step is performed on the sample piece 50 obtained by cutting each rolled copper foil with a copper plating layer and each rolled copper foil without a copper plating layer into a width of 12.5 mm and a length of 220 mm (220 mm in the rolling direction). Following this, recrystallization annealing was performed at 300 ° C. for 5 minutes. Such a condition imitates an example of the amount of heat that the rolled copper foil actually receives in close contact with the substrate in the CCL process of the flexible printed wiring board.

  Next, as shown in FIG. 6, the sample piece 50 was fixed to the sample fixing plate 11 of the sliding bending test apparatus 10 with screws 12. Subsequently, the specimen piece 50 was attached in contact with the vibration transmission section 13, and the vibration transmission section 13 was vibrated in the vertical direction by the oscillation driver 14 to transmit vibration to the specimen piece 50, and a bending fatigue life test was performed. . As the measurement conditions for the bending fatigue life, the bending radius 10r was 1.5 mm, the stroke 10 s was 10 mm, and the amplitude number was 25 Hz. Under such conditions, each of the sample pieces 50 was measured three times, and the average value of the number of bendings until the fracture occurred was compared. The measurement results thus obtained are shown in Table 3 below.

  In Table 3, sample pieces 50 having different thicknesses are mixed. It should be noted that the thickness of the sample piece 50 affects the number of times of bending until breakage, that is, the bending resistance. That is, if the materials are substantially the same, in general, the number of bendings until rupture decreases as the thickness increases. Therefore, in each sample piece 50 shown in Table 3, the bending resistance decreases as the total thickness, that is, the total thickness increases, regardless of the presence or absence of a copper plating layer having a thin layer thickness relative to the rolled copper foil. .

  Looking at Example 1 and Comparative Examples 1 and 3 in which the total thickness of the copper plating layer and the rolled copper foil was 20.0 μm, the number of bendings until the break (number of bending breaks) was Comparative Example 3, Comparative Example 1, It is increasing in the order of Example 1. In Example 1, the rolled copper foil before forming the copper plating layer, that is, the number of bending breaks of 90% or more with respect to the number of bending breaks of Comparative Example 5 was obtained. Considering that the thickness of Example 1 is greater than that of Comparative Example 5, it is considered that there was almost no decrease in flex resistance due to the provision of the copper plating layer in Example 1. On the other hand, the number of bending breaks of Comparative Examples 1 and 3 decreased to about 60% and 35% of Example 1, respectively.

  Next, in Example 2 and Comparative Examples 2 and 4 in which the total thickness of the copper plating layer and the rolled copper foil is 12.0 μm, the number of bendings until the break (the number of bending breaks) is Comparative Example 4 and It is increasing in the order of Example 2 and Example 2. In Example 2, the rolled copper foil before forming the copper plating layer, that is, the number of bending breaks of 90% or more with respect to the number of bending breaks of Comparative Example 6 was obtained. The thickness of Example 2 is greater than that of Comparative Example 6. As described above, considering that the bending resistance decreases as the overall thickness increases, it is considered that there was almost no decrease in bending resistance due to the provision of the copper plating layer in Example 2. On the other hand, the number of bending breaks in Comparative Examples 2 and 4 decreased to about 60% and 30% of Example 2, respectively.

  As described above, in Examples 1 and 2 having the biaxially oriented {002} plane, the effect of improving the bending resistance was recognized.

(2) Rolled copper foil with a copper plating layer using a dilute copper alloy of oxygen-free copper Next, according to Examples 3 and 4 and Comparative Examples 7 to 10 using a dilute copper alloy having oxygen-free copper as a parent phase A rolled copper foil with a copper plating layer and a rolled copper foil without a copper plating layer according to Comparative Examples 11 and 12 were produced, and various evaluations were performed on each.

(Production of rolled copper foil with copper plating layer)
By the same procedure and method as the above-mentioned Example, the rolled copper foil with a copper plating layer according to Examples 3 and 4 and Comparative Examples 7 to 10 and the rolled copper foil without a copper plating layer according to Comparative Examples 11 and 12 were used. Produced.

  At this time, a dilute copper alloy in which Sn was added to oxygen-free copper having a purity of 99.99% within a range of 30 ppm to 80 ppm was used as a raw material. Since the addition amount of Sn is very small, its concentration is defined within the predetermined range as described above for accuracy.

  The temperature condition of each annealing process was matched with the heat resistance of the copper material which consists of a dilute copper alloy. Specifically, the conditions of the intermediate annealing process were set to a temperature of 750 ° C. to 850 ° C. for about 2 minutes to 4 minutes. The conditions of the dough annealing process were set at a temperature of about 800 ° C. for about 2 minutes. In the final cold rolling step, rolled copper foils according to Example 3 and Comparative Examples 7 and 9 having a total workability of 95% and a thickness of 16.0 μm were manufactured. Moreover, the rolled copper foil which concerns on Example 4 and Comparative Examples 8 and 10 with a total workability of 97% and a thickness of 8.0 μm was manufactured.

  Moreover, the copper plating layer was formed in the rolling surface of Examples 3 and 4 and Comparative Examples 7-10. At this time, the thickness of the copper plating layer was all 0.5 μm. Table 4 shows the plating conditions for each rolled copper foil.

  Under each condition in Table 4, a copper plating layer having the same level of flatness was obtained. The surface roughness of the copper plating layer was 0.5 μm to 0.8 μm in terms of ten-point average roughness Rzjis (JIS B0601: 2001).

({022} face pole figure measurement)
About the rolled copper foil with the copper plating layer according to Examples 3 and 4 and Comparative Examples 7 to 10 obtained as described above and the copper plating layer without the copper plating layer according to Comparative Examples 11 and 12, the copper plating layer and The crystal orientation of the rolled copper foil was measured by the same procedure and method as in the above examples.

  The result of the pole figure measurement of Example 3 and Comparative Examples 7, 9, and 11 is shown in FIGS.

  FIG. 7A, FIG. 8A, and FIG. 9A show the measurement results of the copper plating layers of Example 3 and Comparative Examples 7 and 9. FIG. Moreover, the measurement result of the rolled copper foil of the comparative example 11 is shown by FIG.7 (b), FIG.8 (b), and FIG.9 (b) for the comparison. Moreover, the upper part of each figure is a pole figure, and the lower part is the spectrum of the diffraction peak of the pole figure measurement. The horizontal axis is the rotation angle β (°), and the vertical axis is the diffraction intensity (arbitrary unit).

  As shown in FIG. 7 (a), in the copper plating layer of Example 3, fourfold symmetry is observed in the diffraction peak. In addition, the region other than the diffraction peak showing the fourfold symmetry shows a random orientation. Therefore, it can be seen that the crystal structure of the copper plating layer of Example 3 is in a state where only the {002} plane is biaxially oriented in a crystal mainly composed of random orientations. In Example 4, similar results were obtained.

  In addition, in the upper part of FIG. 7A, some uneven distribution is recognized near the center of the pole figure, that is, when the tilt angle is around 90 °. That is, the random orientation in the copper plating layer of Example 3 is considered to be a quasi-random orientation. Also in this case, the effect of the {002} plane biaxially oriented is exhibited.

  Further, as shown in FIG. 8A, in the copper plating layer of Comparative Example 7, no four-fold symmetry is observed in the diffraction peak. In Comparative Example 8, the same result was obtained.

  In addition, in the upper part of FIG. 8A, some uneven distribution is recognized near the center of the pole figure. Since the unevenly oriented crystal orientation is considered to be the {022} plane, when the copper plating layer is formed, it is the crystal orientation of the rolled copper foil after the final cold rolling step and before the recrystallization annealing step {022}. } It seems that it was affected by the surface. That is, it seems that a part of the copper plating layer was epitaxially grown following the {022} plane of the rolled copper foil.

  9A, the copper plating layer of Comparative Example 9 has a diffraction peak substantially similar to the diffraction peak of the underlying rolled copper foil shown in FIG. 9B. Obtained. From this, it can be seen that in Comparative Example 9, the copper plating layer was epitaxially grown following the crystal structure of the rolled copper foil. In addition, no four-fold symmetry is observed in the diffraction peak. In Comparative Example 10, similar results were obtained.

  The difference between the above Examples and Comparative Examples may be influenced by whether or not a predetermined amount or more of various additives are added to the plating bath during the formation of the copper plating layer.

(Bending fatigue life test)
Next, the bending resistance of each rolled copper foil and each rolled copper foil with a copper plating layer was measured by the same procedure and method as in the above-described Examples. The obtained measurement results are shown in Table 5 below.

  In Table 5, it should be noted that sample pieces 50 having different thicknesses are mixed and affect the bending resistance.

  Looking at Example 3 and Comparative Examples 7 and 9 in which the total thickness of the copper plating layer and the rolled copper foil is 16.5 μm, the number of bendings until the break (the number of bending breaks) is Comparative Example 9, Comparative Example 7, It is increasing in the order of Example 3. In Example 3, the rolled copper foil before forming the copper plating layer, that is, the number of bending breaks of 90% or more with respect to the number of bending breaks of Comparative Example 11 was obtained. Considering that the thickness of Example 3 is greater than that of Comparative Example 11, it is considered that there was almost no decrease in flex resistance due to the provision of the copper plating layer in Example 3. On the other hand, the number of bending breaks of Comparative Examples 7 and 9 has decreased to about 60% and 50% of Example 3, respectively.

  Next, in Example 4 and Comparative Examples 8 and 10 in which the total thickness of the copper plating layer and the rolled copper foil is 8.5 μm, the number of bendings until the break (the number of bending breaks) is as follows. It is increasing in the order of Example 8 and Example 4. In Example 4, the rolled copper foil before forming the copper plating layer, that is, the number of bending breaks of 90% or more with respect to the number of bending breaks of Comparative Example 12 was obtained. Considering that the thickness of Example 4 is greater than that of Comparative Example 12, it is considered that there was almost no decrease in flex resistance due to the provision of the copper plating layer in Example 4. On the other hand, the number of bending breaks of Comparative Examples 8 and 10 has decreased to about 60% and 50% of Example 2, respectively.

  As described above, even when a dilute copper alloy having oxygen-free copper as a parent phase was used, in Examples 3 and 4 having {002} planes biaxially oriented, the effect of improving the bending resistance was recognized.

(3) Rolled copper foil with copper plating layer using tough pitch copper Here, examples and comparative examples using tough pitch copper and examples and comparative examples using a dilute copper alloy having tough pitch copper as a parent phase Various evaluations were performed.

  First, Examples 5 and 6 using tough pitch copper and rolled copper foil with a copper plating layer according to Comparative Examples 13 to 16 and rolled copper foil without a copper plating layer according to Comparative Examples 17 and 18 were manufactured. Various evaluations were performed. About the rolled copper foil with a copper plating layer, all the thickness of the copper plating layer was 1.5 micrometers. The results are shown in Table 6 below.

  In any of the examples, a biaxially oriented {002} plane was observed, and the bending resistance was improved. Further, in any of the comparative examples, the {002} plane with biaxial orientation was not recognized, and the effect of improving the bending resistance was not obtained.

  Further, Examples 7 and 8 using a dilute copper alloy in which Ag is added to tough pitch copper in a range of 150 ppm to 250 ppm, and rolled copper foil with a copper plating layer according to Comparative Examples 19 to 22, and Comparative Examples 23 and 24 The rolled copper foil without such a copper plating layer was manufactured, and various evaluation was performed about each. About the rolled copper foil with a copper plating layer, all the thickness of the copper plating layer was 0.5 micrometer. The results are shown in Table 7 below.

  In any of the examples, a biaxially oriented {002} plane was observed, and the bending resistance was improved. Further, in any of the comparative examples, the {002} plane with biaxial orientation was not recognized, and the effect of improving the bending resistance was not obtained.

  As described above, even when using tough pitch copper or a dilute copper alloy having tough pitch copper as a parent phase, the effect of improving the bending resistance was confirmed in the example having the biaxially oriented {002} plane.

DESCRIPTION OF SYMBOLS 10 Sliding bending test apparatus 11 Sample fixing plate 12 Screw 13 Vibration transmission part 14 Oscillation drive body 50 Sample piece

Claims (7)

After the final cold rolling process, the rolled copper foil before the recrystallization annealing process,
A copper plating layer formed on at least one surface of the main surface of the rolled copper foil or its back surface, and having a plurality of crystal faces mainly composed of random orientations, and
In the {022} plane pole figure measurement based on the surface of the copper plating layer, the diffraction peak of the {022} plane obtained by in-plane rotation of the surface of the copper plating layer when the tilt angle α is 45 ° is the in-plane Rolled copper foil with a copper plating layer, characterized in that crystal grains having a 4-fold symmetry existing every 90 ° ± 5 ° of the rotation angle β of rotation are present in a random orientation in the copper plating layer . The rolled copper foil with a copper plating layer according to claim 1, wherein the rolled copper foil takes the form of a pure copper type texture composed of pure copper or a diluted copper alloy. The rolled copper foil with a copper plating layer according to claim 1 or 2, wherein the total thickness of the copper plating layer and the rolled copper foil is 1 µm or more and 20 µm or less. The rolled copper foil with a copper plating layer according to any one of claims 1 to 3, wherein the copper plating layer is thinner than the rolled copper foil. It is an object for flexible printed wiring boards, The rolled copper foil with a copper plating layer in any one of Claims 1-4 characterized by the above-mentioned. After the final cold rolling process, the rolled copper foil before the recrystallization annealing process,
A copper plating layer formed on at least one surface of the main surface of the rolled copper foil or its back surface, and having a plurality of crystal faces mainly composed of random orientations, and
A rolled copper foil with a copper plating layer, wherein biaxially oriented {002} plane crystal grains are present in a random orientation in the copper plating layer. The biaxially oriented {002} plane crystal grains are
The {022} plane pole figure measurement exists in the random orientation in the copper plating layer at a ratio equal to or higher than the detection limit of a diffraction peak indicating the presence of the biaxially oriented {002} plane. 6. A rolled copper foil with a copper plating layer according to 6.