JP2014152352A - Composite copper foil and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high adhesiveness to a substrate while keeping transmissivity of the substrate.SOLUTION: A composite copper foil comprises rolled copper foil, a copper plated layer formed on at least one side of the rolled copper foil and a roughened copper plated layer containing coarse particles of an average particle size of 0.05-0.30 μm. The ratio in particle size difference of the maximum particle size and the minimum particle size of the coarse particles is 65% or lower. In a cross section of the roughened copper plated layer cut in the thickness direction, coarse particles line up, continuously without intervals, on the copper plated layer throughout a distance of 20 μm or longer.

Description

  The present invention relates to a composite copper foil including a copper plating layer and a roughened copper plating layer, and a method for producing the composite copper foil.

  A flexible printed circuit (FPC) is thin and excellent in flexibility. For this reason, the FPC is often used for wiring of a movable part of a disk-related device in addition to a folding part of a folding cellular phone, a movable part such as a digital camera or a printer head.

  As the FPC wiring material, rolled copper foil or the like having excellent bending resistance that can withstand repeated bending than electrolytic copper foil or the like is used. The rolled copper foil for FPC is bonded to an FPC base film (base material) made of a resin such as polyimide by heating or the like in the FPC manufacturing process.

  At this time, in order to improve the adhesion between the rolled copper foil and the FPC base material, for example, a roughened copper plating layer containing roughened grains may be provided on at least one surface of the rolled copper foil. As the grain size of the roughened grains increases and the surface roughness of the rolled copper foil increases, the adhesion with the base material is improved by the anchor effect. When a roughened copper plating layer is formed, a copper plating layer may be provided on a rolled copper foil and smoothed in advance (for example, Patent Documents 1 and 2).

JP 2004-238647 A JP 2006-155899 A

  However, if the surface roughness of the composite copper foil provided with the copper plating layer or the roughened copper plating layer becomes too large, the unevenness of the composite copper foil may be transferred to the substrate on which the composite copper foil is bonded. The base material to which the unevenness is transferred has a reduced transmittance, and, for example, when the FPC is mounted on an electronic device or the like, the alignment is hindered.

  On the other hand, if the surface roughness of the composite copper foil is reduced by reducing the roughened grains of the roughened copper plating layer, sufficient adhesion to the substrate cannot be obtained, and the reliability of the wiring made of the composite copper foil Will fall.

  The objective of this invention is providing the manufacturing method of the composite copper foil and composite copper foil with which high adhesiveness with a base material is acquired, maintaining the transmittance | permeability of a base material.

According to a first aspect of the invention,
Rolled copper foil,
A copper plating layer formed on at least one side of the rolled copper foil;
A roughened copper plating layer formed on the copper plating layer and including roughening grains having an average particle size of 0.05 μm or more and 0.30 μm or less, and
The ratio of the particle size difference between the maximum particle size and the minimum particle size of the roughened particles is 65% or less,
Provided is a composite copper foil in which the roughened grains are continuous on the copper plated layer over a distance of 20 μm or more at a cut surface that cuts the roughened copper plated layer in the thickness direction. Is done.
However, the ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100.

According to a second aspect of the invention,
Rolled copper foil,
A copper plating layer formed on at least one side of the rolled copper foil;
A roughened copper plating layer formed on the copper plating layer and including roughening grains having an average particle size of 0.05 μm or more and 0.30 μm or less, and
The ratio of the particle size difference between the maximum particle size and the minimum particle size of the roughened particles is 65% or less,
In the scanning electron microscope, a composite copper foil is provided in which the area of the non-formed portion of the roughened grains existing in the field of view of 10,000 times is 5 μm ² or less.
However, the ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100.

According to a third aspect of the invention,
When the concave portion exists on the surface of the copper plating layer, the composite copper foil according to the first or second aspect, in which an average depth of the concave portion is 0.60 μm or less, is provided.

According to a fourth aspect of the invention,
The copper plating layer is
The composite copper in any one of the 1st-3rd aspect currently formed using the copper plating solution which added the organic sulfur compound which has a mercapto group, surfactant, a leveling agent, and a chloride ion. A foil is provided.

According to a fifth aspect of the present invention,
When the roughened copper plating layer is averaged, the composite copper foil according to any one of the first to fourth aspects is provided, which corresponds to a thickness of 0.05 μm or more and 0.25 μm or less.

According to a sixth aspect of the present invention,
The composite copper foil in any one of the 1st-5th aspect provided with the rust prevention layer whose thickness is 11 nm or more and 70 nm or less on the said roughening copper plating layer is provided.

According to a seventh aspect of the present invention,
A nickel plating layer, a zinc plating layer, a chromate treatment layer, and a silane coupling treatment layer are formed in this order on the roughened copper plating layer, and first to first rust prevention layers having a thickness of 11 nm to 70 nm are provided. A composite copper foil according to any of the sixth aspects is provided.

According to an eighth aspect of the present invention,
Forming a copper plating layer on at least one side of the rolled copper foil;
Forming a roughened copper plated layer containing roughened grains having an average particle size of 0.05 μm or more and 0.30 μm or less on the copper plated layer;
In the step of forming the copper plating layer,
There is provided a method for producing a composite copper foil in which the copper plating layer is formed using a copper plating solution to which an organic sulfur compound having a mercapto group, a surfactant, a leveling agent, and chloride ions are added.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the composite copper foil and composite copper foil with which high adhesiveness with a base material is obtained, maintaining the transmittance | permeability of a base material is provided.

It is a flowchart which shows the manufacturing process of the composite copper foil which concerns on one Embodiment of this invention. The upper row is a surface observation photograph of the roughened foil according to Example 8 of the present invention, and the lower row is a surface observation photograph of the roughened foil according to Comparative Example 4. The upper part is a cross-sectional observation photograph of the roughened foil according to Example 8 of the present invention, and the lower part is a cross-sectional observation photograph of the roughened foil according to Comparative Example 4. It is a schematic diagram which illustrates the state without a roughening omission in a roughening copper plating layer. It is the surface observation photograph of FPC which shows the light transmittance in the base material of FPC, and the visibility of wiring. It is a cross-sectional observation photograph of FPC which shows the crevice which arises by pasting together the composite copper foil concerning the prior art, and the substrate of FPC.

<Knowledge obtained by the present inventors>
As described above, in order to improve the adhesion of the FPC to the base material, a composite copper foil in which a copper plating layer and a roughened copper plating layer are formed in this order on at least one surface of the rolled copper foil may be used. . In order to form such a roughened copper plating layer, for example, a copper plating layer is formed on a rolled copper foil and smoothed, and then, for example, roughening is performed in a copper plating solution at a current density equal to or higher than a limit current density. Process. Thereby, roughened grains are attached to the surface of the copper plating layer to form an uneven shape. For example, the particle size can be increased by increasing the current value at the time of the roughening treatment, or performing the roughening treatment in several stages, and the surface roughness can be controlled.

  At this time, when the roughened grains included in the roughened copper plating layer are enlarged and the surface roughness of the composite copper foil becomes too large, the surface irregularities are transferred to the base material on which the composite copper foil is bonded, and The transmittance may decrease. When mounting an FPC on an electronic device or the like, for example, by using a CCD camera or the like, the position of the wiring formed by removing a part of the composite copper foil bonded to the base material is confirmed through the base material of the FPC. Align with the device. If the unevenness of the composite copper foil is transferred to the exposed base material after the composite copper foil is removed and the transmittance of the base material is reduced, it will take time for alignment and the mounting work efficiency will decrease. It becomes impossible to match. FIG. 5 shows the state observed with a metal microscope.

  As shown in FIG. 5 (a), if the transmittance of the base material is kept good, the end of the wiring, that is, the boundary between the wiring and the base material, is not a shade of light in the observation region. This can be clearly seen as a difference. On the other hand, FIG. 5B shows a case where the unevenness is transferred by bonding with the composite copper foil having a large surface roughness and the transmittance of the base material is lowered. It can be seen that the shading indicating the boundary between the wiring and the substrate is unclear. In addition, the case where the roughening grain shown by FIG.5 (c) is extremely small is mentioned later.

  In the composite copper foil for FPC, the present inventors tried to suppress the growth of roughening grains provided in the roughened copper plating layer by shortening the plating time of the roughening treatment as much as possible in order to eliminate such problems. .

  However, when trying to reduce the roughening grains provided in the roughened copper plating layer, there are portions where the plating is not locally deposited on the copper plating layer, non-growing portions where the roughening grains do not grow, so-called roughening missing portions. It sometimes happened. In the non-growth portion of the roughened grains, the surface roughness is extremely lowered. Moreover, in such a non-growth part, it becomes easy to produce a clearance gap between composite copper foil and a base material. Thereby, sufficient anchor effect is not acquired between composite copper foil and a base material, but adhesiveness will fall. When the FPC is immersed in a chemical or the like, the chemical durability may be reduced. In FIG. 6, a mode that the clearance gap produced between composite copper foil and a base material is shown.

  In addition, when there is such a non-growth part, the uneven pattern of the composite copper foil transferred to the base material is not uniform, and unevenness occurs in the shade when the base material is viewed through the FPC alignment. As a result, the visibility of the wiring may be reduced. The above-mentioned FIG.5 (c) is an example which visibility fell because the coarse grain is extremely small. In the example shown in FIG. 5C, the wiring portion appears shining, and the wiring boundary is difficult to identify.

  The inventors of the present invention made further studies and found out that the above-mentioned roughening omission occurs due to the influence of the state of the underlying copper plating layer. That is, it came to the idea that such roughening omission can be suppressed by optimizing the state of the copper plating layer. In addition, the present inventors have also found a method of forming a copper plating layer in a state where roughening omission can be suppressed.

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

<One Embodiment of the Present Invention>
(1) Structure of composite copper foil First, the structure of the composite copper foil which concerns on one Embodiment of this invention is demonstrated.

  The composite copper foil according to the present embodiment includes a rolled copper foil, a copper plating layer formed on at least one surface of the rolled copper foil, and a roughened copper plating layer formed on the copper plating layer. Moreover, the composite copper foil which concerns on this embodiment is equipped with a rust prevention layer on a roughening copper plating layer.

  The composite copper foil configured as described above is used, for example, as a flexible wiring material in an FPC by bonding the roughened surface side on which a roughened copper plating layer is formed to an FPC base material.

(Outline of rolled copper foil)
The rolled copper foil included in the composite copper foil is configured in a plate shape including a rolled surface as a main surface, for example. This rolled copper foil is, for example, an ingot made of pure copper such as oxygen-free copper (OFC) or tough pitch copper (TPC), hot rolling process, cold rolling process, etc. A rolled copper foil having a predetermined thickness. The rolled copper foil according to the present embodiment is intended to have excellent bending resistance by being subjected to recrystallization when subjected to a recrystallization annealing process that also serves as a bonding process with an FPC base material, for example. Has been.

  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. 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.

(Overview of copper plating layer)
The copper plating layer with which the composite copper foil is provided is formed on the rolled surface as the main surface of the rolled copper foil, or on at least one surface of the back surface by using, for example, electrolytic plating. Moreover, the copper plating layer which concerns on this embodiment is 0.1 micrometer or more and 0.4 micrometer or less in thickness, for example.

  By setting the thickness of the copper plating layer to, for example, 0.1 μm or more, it becomes easy to uniformly perform roughening copper plating (roughening treatment) on the copper plating layer. On the other hand, when the copper plating layer is 0.4 μm or less, the electrolytic plating time does not become unnecessarily long, and the productivity can be improved. Moreover, the bending resistance of the whole composite copper foil can be improved more reliably after the heat treatment. This is because when the copper plating layer that is difficult to recrystallize is sufficiently thin, the improvement in the bending resistance of the rolled copper foil is hardly hindered.

  In addition, the copper plating layer according to the present embodiment is formed using a copper plating solution to which an organic sulfur compound having a mercapto group, a surfactant, and chloride ions are added, as will be described later. . At least by this, for example, when a recess is present on the surface of the copper plating layer, the average value of the maximum diameter of the recess is 20 μm or less, preferably 15 μm or less, and the average value of the depth of the recess is 0.6 μm or less, preferably 0. It is 5 μm or less. Here, the shape of the concave portion on the surface of the copper plating layer in plan view may be, for example, an irregular shape instead of a perfect circle, and the diameter of the concave portion is defined as the maximum diameter.

  As will be described later, the present inventors have stated that at least one of the reasons why the roughening omission can be suppressed even in the case of a roughened copper plating layer in which the roughening grains are extremely small is as described above. It is considered that the depth of the recess on the surface is set to a predetermined value or less.

(Outline of roughened copper plating layer)
The roughened copper plating layer with which the composite copper foil is provided is formed on the copper plating layer. By providing the composite copper foil with the roughened copper plating layer, the adhesion between the composite copper foil and the FPC substrate can be improved.

  The roughened copper plating layer is mainly composed of roughened grains deposited on the copper plating layer by plating. The roughened grains are, for example, copper (Cu) alone or copper (Cu), iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), chromium (Cr), zinc (Zn), Metal particles containing at least one type, preferably two or more types of tungsten (W). By including other metal particles in this manner, it is possible to suppress the roughened grains from growing in a dendritic shape.

  The average particle diameter of the roughened grains is, for example, 0.05 μm or more and 0.30 μm or less. Moreover, the ratio of the particle size difference between the maximum particle size and the minimum particle size of the roughened particles is 65% or less. However, the ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100. That is, the smaller the particle size difference ratio, the smaller the difference between the maximum particle size and the minimum particle size of the roughened particles.

  The thickness of the roughened copper plating layer including the roughened grains having irregularities is, for example, 0.05 μm or more and less than 0.26 μm, preferably 0.05 μm or more and 0.25 μm, if each roughened grain is averaged. It corresponds to the following thickness.

  By setting the thickness of the roughened copper plating layer to 0.05 μm or more, a sufficient anchor effect can be obtained and the adhesion to the substrate can be improved. On the other hand, it can suppress that the surface roughness of a composite copper foil becomes large too much by making a roughening copper plating layer into less than 0.26 micrometer, and also 0.25 micrometer or less. Further, the electrolytic plating time is not unnecessarily prolonged, and the productivity can be improved. Moreover, it becomes easy to maintain the bending resistance as a whole of composite copper foil by not making a roughening copper plating layer excessively thick.

  Further, in the roughened copper plating layer, the non-growth portion where the roughened grains do not grow, that is, the occurrence of roughening omission is suppressed. This can be seen by observing the state of the roughened copper plating layer in the following state, for example, with a scanning electron microscope (SEM).

  That is, in the roughened copper plating layer in which roughening omission is suppressed, the roughening grains are not interrupted over a distance of 20 μm or more on the cut surface where the roughened copper plating layer is cut in the thickness direction. It is in a state linked to. At this time, one or a plurality of roughened grains grow on the copper plating layer. Therefore, the roughened grains are not interrupted, for example, as shown in FIG. 4A, the roughened grains 20 directly attached on the copper plating layer 10 are adjacent to each other without being separated from each other. Includes state. Further, the roughened grains are not interrupted, for example, as shown in FIG. 4B, the roughened grains 20 directly attached on the copper plating layer 10 are sparse without contacting each other. In addition, one or more roughened grains 20 are further adhered thereon, so that the roughened grains 20 are continuously connected along the surface of the copper plating layer 10. In addition, the above states should just be recognized in the cut surface cut | disconnected in arbitrary directions. Or it is preferable that it is the above-mentioned state in either or both of the cut surfaces cut | disconnected in parallel and perpendicular | vertical to the rolling direction.

Alternatively, in the roughened copper plating layer in which the roughening omission is suppressed, the area of the non-formed portion of the roughened grains existing in the field of view with a magnification of 10,000 times is 5 μm ² or less, preferably 2 μm ² or less. It has become. The portion where the roughened grains are not formed is identified by the fact that the grainy outline of the roughened grains is not recognized and the underlying copper plating layer is exposed. The area of the non-formed portion of the roughened grains is the sum in the field of view with a magnification of 10,000.

  When either one or both of these two states are satisfied, it can be said that the roughened copper plating layer is in a state in which roughening omission is suppressed to the extent that sufficient adhesion to the base material is obtained. That is, the surface roughness of the composite copper foil is sufficiently maintained, and a gap with the base material is hardly generated.

(Outline of rust prevention layer)
As for the rust prevention layer with which composite copper foil is provided, the nickel plating layer, the zinc plating layer, the chromate treatment layer (trivalent chromium chemical conversion treatment layer), and the silane coupling treatment layer were formed on the roughened copper plating layer in this order, for example. A laminated structure is provided. The anticorrosive layer is, for example, equivalent to a thickness of 0.1 g / m ² or more and 0.6 g / m ² or less, that is, a thickness of 11 nm or more and 70 nm or less in terms of a plating amount. More specifically, for example, the nickel plating layer has a thickness of 9 nm to 50 nm, the zinc plating layer has a thickness of 1 nm to 10 nm, and the chromate treatment layer has a thickness of 1 nm to 10 nm. The silane coupling treatment layer is an extremely thin layer.

  By providing the composite copper foil with a rust prevention layer, the heat resistance and chemical resistance of the composite copper foil are improved. At this time, by making the thickness of the anticorrosive layer within the above-mentioned predetermined range, it is possible to obtain sufficient heat resistance and chemical resistance and not impair the ease of etching.

  Specifically, among the layers constituting the rust prevention layer, the nickel plating layer suppresses copper diffusion. Moreover, the galvanized layer improves the heat resistance. The chromate treatment layer and the silane coupling treatment layer function as a chemical conversion treatment layer (chemical conversion treatment film). In particular, the silane coupling treatment layer improves the chemical adhesion between the composite copper foil and the substrate.

  In addition, even when a copper plating layer or a roughened copper plating layer is formed only on one side of the rolled copper foil, such a rust preventive layer is formed on the side on which the roughened copper plating layer is formed, You may form at least one part of such a rust preventive layer, for example, a nickel plating layer, a zinc plating layer, and a chromate treatment layer, on the surface on the opposite side to this of a rolled copper foil. Thereby, heat resistance and chemical resistance can be improved even on the side of the composite copper foil that does not include a copper plating layer.

(Action of suppressing roughening loss)
The effect | action in which the roughening omission of a roughening copper plating layer is suppressed in the composite copper foil comprised as mentioned above is demonstrated below.

  When forming the roughened copper plating layer, if the plating time for the roughening treatment is shortened as much as possible to suppress the growth of the roughened grains and small roughened grains are formed, the roughened copper plating layer is not roughened as described above. Etc. may occur. Thereby, the adhesiveness of composite copper foil and a base material, and the boundary visibility of wiring may fall.

  As a result of diligent research, the present inventors have formed a copper plating layer by a predetermined method to be described later, and can form a roughened copper plating layer in which roughening omission is suppressed by using this as a base. I found what I could do. That is, it is possible to form the copper plating layer in a state in which roughening omission can be suppressed by a predetermined method. The specific state of the copper plating layer at this time and the mechanism by which the state contributes to the suppression of roughening loss are under further study.

  However, according to the present inventors, in such a copper plating layer, at least a slight depression existing on the copper plating layer, that is, the depth of the concave portion on the surface is larger than the copper plating layer formed by other methods. Is known to be smaller. Furthermore, the present inventors have confirmed that many of these roughening defects occur on the surface of the recesses exceeding a predetermined size on the copper plating layer.

  Such a concave portion on the surface of the copper plating layer is considered to be an oil pit or the like originally present on the surface of the rolled copper foil without being completely filled with the copper plating layer. The oil pit is a depression formed by rolling oil used at the time of rolling, for example, into the surface of a plate material to be rolled by a rolling roll. The depth of the oil pit on the surface of the rolled copper foil is, for example, 0.7 μm or more and 1.0 μm or less.

  The present inventors have considered as follows that roughening is lost on the surface of such a recess.

  The roughening process is performed at a current density equal to or higher than the limit current density. For this reason, it is thought that an electric field is influenced by the slight unevenness | corrugation of the copper plating layer used as a foundation | substrate. That is, current tends to concentrate on the convex portion, and plating is likely to grow. On the other hand, it is difficult for current to concentrate in the recess, and the plating is difficult to grow.

  From this, the present inventors considered that when the concave portion existing on the surface of the copper plating layer exceeds the above-mentioned predetermined size, roughening loss tends to occur on the surface of the concave portion. At this time, it is considered that the smaller the roughened grains are, the more easily affected by the slight unevenness of the copper plating layer.

  On the other hand, the edge of the recess has a convex shape, and in such a convex portion, the roughened grains become enlarged or the roughened grains grow in a dendritic shape, which also causes roughened copper plating. There is also a possibility that the unevenness of the layer increases and the surface roughness becomes too large.

  In order to solve the problems as described above, the copper plating layer according to the present embodiment is configured such that at least the size of the recesses on the surface is a predetermined value or less. Thereby, even if it shortens the plating time of a roughening process as much as possible and makes a roughening grain extremely small, roughening omission etc. can be controlled. The difference between the maximum particle size and the minimum particle size of the roughened particles is also easily reduced.

  In addition, since the size of the concave portion on the surface of the copper plating layer is a predetermined value or less, the difference between the maximum particle size and the minimum particle size of the roughened particles, that is, the ratio of the particle size difference obtained by the above formula The generation of dendrites and the like can be suppressed.

  However, in the present embodiment, since the roughened grains are fine, roughening is likely to occur, but abnormal growth such as dendrite is unlikely to occur. Therefore, as described above, if the depth of the concave portion is set to 0.6 μm or less, for example, it is considered that abnormal growth can be suppressed with certainty and the roughening loss can be sufficiently reduced. If the depth of the recess is, for example, 0.5 μm or less, abnormal growth can be more reliably suppressed.

  As will be described later, according to the present inventors, it has also been found that the copper plating layer formed by a predetermined method is easily recrystallized in the recrystallization annealing process performed in the FPC manufacturing process. On the other hand, copper plating layers formed by other methods are hardly recrystallized in the same process. Therefore, it can be said that the copper plating layer according to the present embodiment potentially has such a state that it is easily recrystallized as a unique state. It is also possible that

(2) Manufacturing method of composite copper foil The present inventors conducted earnest research in order to form the copper plating layer which can suppress the roughening omission of a roughening copper plating layer. As a result, a predetermined effect was obtained by the following method, which will be described here.

  The manufacturing method of the composite copper foil which concerns on one Embodiment of this invention is demonstrated using FIG. FIG. 1 is a flowchart showing the manufacturing process of the composite copper foil according to the present embodiment.

(Rolled copper foil preparation step S10)
As shown in FIG. 1, first, a rolled copper foil serving as a raw foil is prepared. As described above, the rolled copper foil is made of pure copper made of oxygen-free copper or tough pitch copper, or a dilute copper alloy having these as a parent phase. Such a raw material ingot is subjected to a hot rolling process, a repeating process of repeating a cold rolling process and an annealing process, and a final cold rolling process to obtain a rolled copper foil having a predetermined thickness.

(Copper plating layer forming step S20)
Next, electrolytic degreasing and pickling treatment S21 and copper plating treatment S22 are performed, and a copper plating layer forming step S20 is performed to form a copper plating layer on at least one surface of the rolled copper foil. In addition, a water washing process is performed between each process.

  That is, the surface of the rolled copper foil is cleaned by performing electrolytic degreasing and pickling treatment S21. As electrolytic degreasing, for example, cathodic degreasing using an alkaline solution such as sodium hydroxide is performed. As the alkaline solution, for example, an aqueous solution containing 20 g / L to 60 g / L of sodium hydroxide and 10 g / L to 30 g / L of sodium carbonate can be used.

  As the pickling treatment, for example, the rolled copper foil is immersed in an acidic aqueous solution such as sulfuric acid, and the alkali component remaining on the surface of the rolled copper foil is neutralized and the copper oxide film is removed. As the acidic aqueous solution, for example, an aqueous solution containing 120 g / L or more and 180 g / L or less of sulfuric acid, an acidic aqueous solution such as citric acid, a copper etching solution, or the like can be used.

  Subsequently, a copper plating process S22 is performed to form a copper plating layer on the rolled copper foil. As the copper plating treatment S22, for example, an electrolytic treatment using a rolled copper foil as a cathode in an acidic copper plating bath mainly composed of copper sulfate and sulfuric acid is performed.

At this time, the liquid composition, the liquid temperature, and the electrolysis conditions of the acidic copper plating bath can be selected from a wide range and are not particularly limited, but are preferably selected from the following ranges, for example.
Copper sulfate pentahydrate: 20 g / L or more and 300 g / L or less Sulfuric acid: 10 g / L or more and 200 g / L or less Liquid temperature: 15 ° C. or more and 50 ° C. or less Current density: 2 A / dm ² or more and 15 A / dm ² or less Processing time: 1 second to 20 seconds

  More preferably, the copper sulfate pentahydrate can be 50 g / L or more and 300 g / L or less, the sulfuric acid can be 30 g / L or more and 200 g / L or less, and the like.

  In addition, the current density at this time is full of the limit current density. In other words, the current density is not so-called burnt plating. In this way, by setting the current density at the end of the limit current density, unevenness on the surface of the copper plating layer can be reduced and smoothing can be achieved. However, the higher the current density, the higher the plating speed and the higher the productivity. Therefore, it is preferable that the current density be less than the limit current density under predetermined plating conditions and as high as possible.

  At this time, by setting the treatment time to 1 second or more and 20 seconds or less, for example, the thickness of the copper plating layer can be made 0.1 μm or more and 0.4 μm or less.

  In addition, a predetermined organic additive is added to the above-described acidic copper plating bath. Examples of organic additives include compounds having mercapto groups such as 3-mercapto-1-sulfonic acid (hereinafter also referred to as MPS) and bis (3-sulfopropyl) disulfide (hereinafter also referred to as SPS), polyethylene glycol And a surfactant such as polypropylene glycol, a leveling agent such as diallyldialkylammonium alkyl sulfate, and a chloride ion such as hydrochloric acid (HCl aqueous solution) are used in a predetermined combination.

  Specifically, a powder reagent of bis (3-sulfopropyl) disulfide as an organic sulfur compound is 5 mg / L to 40 mg / L, polypropylene glycol is 1 ml / more to 4 ml / L as a surfactant, and diallyldialkyl as a leveling agent. An additive in which ammonium alkyl sulfate is 0.1 g / L or more and 2.0 g / L or less and hydrochloric acid is used as chloride ion in combination of 0.05 ml / L or more and 0.3 ml / L or less can be used.

  At this time, it is also possible to use an additive for copper plating in which these organic additives are blended in advance. As such an additive for copper plating, for example, Top Lucina LS manufactured by Okuno Pharmaceutical Co., Ltd., Capper Grime CLX manufactured by Meltex Co., Ltd., CU-BRITETH-RIII manufactured by Sugawara Eugene Corporation, and manufactured by Uemura Industrial Co., Ltd. Sulcup EUC and the like. Any one of these is used at a predetermined concentration, a predetermined formulation, or in combination with the various additives described above.

  As an example of using such an additive for copper plating, bis (3-sulfopropyl) disulfide as an organic sulfur compound is 10 mg / L or more and 60 mg / L or less, and as a surfactant, for example, polyethylene having a molar mass of about 3000 g / mol. 50 mg / L to 300 mg / L of glycol, 3 ml / L to 10 ml / L of CU-BRITETH-RIII manufactured by Sugawara Eugleite Co., Ltd. as a leveling agent, and 0.05 ml / L to 0.001 of hydrochloric acid as chloride ion. An aqueous solution containing 3 ml / L or less can be used.

  These organic additives are used as brighteners and surfactants in the copper plating process. However, the present inventors have found that by using these organic additives in a predetermined combination, the formed copper plating layer can be in a state in which roughening omission can be suppressed. Such a state includes that the depth of the concave portion on the surface of the copper plating layer is a predetermined value or less. That is, it is considered that the effect of filling the depressions such as oil pits of the rolled copper foil with the copper plating layer is enhanced by the action of at least the above-described organic additive, and the size of the concave portion that can exist on the surface of the copper plating layer can be reduced. .

  The present inventors speculate that a compound having a mercapto group may promote the effect of preferentially filling the depression of the rolled copper foil. There is a possibility that a synergistic effect is caused such that chloride ions further enhance such a function of the compound having a mercapto group. When these organic additives are not used, the effect is clear from the fact that the size of the recesses cannot be suppressed within the above range.

  In addition, by using these organic additives in a predetermined combination, the present inventors recrystallized not only the rolled copper foil but also the copper plating layer in the recrystallization annealing process performed in the FPC manufacturing process. I found out. According to the present inventors, it is presumed that, when the copper plating layer is formed, any energy necessary for recrystallization of the copper plating layer is accumulated in the copper plating layer by these organic additives. At this time, the surfactant may be in a state in which the copper plating layer is easily recrystallized by lowering the threshold value at which the self-annealing of the copper plating layer, that is, the phenomenon in which recrystallization proceeds naturally at room temperature, is lowered. There is sex. Thereby, at least the bending resistance of the composite copper foil can be further improved. Moreover, the influence on the roughening omission suppression effect of the roughening copper plating layer by having potentially the state which a copper plating layer is easy to recrystallize is earnestly researching.

  These effects, uses and usages found by the present inventors are completely different from the conventional effects, uses and usages of these organic additives such as brighteners and surface-active images. is there.

  As described above, the rolled copper foil with a copper plating layer according to the present embodiment is formed.

(Roughening copper plating layer forming step S30)
Next, a roughening copper plating layer forming step S30 for forming a roughening copper plating layer on the copper plating layer is performed. In addition, a water washing process is performed between each process.

  That is, for example, electrolytic treatment using a rolled copper foil as a cathode is performed in an acidic copper plating bath containing copper sulfate and sulfuric acid as main components, and the roughened grains are adhered to the surface of the copper plating layer.

At this time, the liquid composition, the liquid temperature, and the electrolysis conditions of the acidic copper plating bath can be selected from a wide range and are not particularly limited, but are preferably selected from the following ranges, for example.
Copper sulfate pentahydrate: 20 g / L or more and 300 g / L or less Sulfuric acid: 10 g / L or more and 200 g / L or less Liquid temperature: 15 ° C. or more and 50 ° C. or less Current density: 20 A / dm ² or more and 100 A / dm ² or less Treatment time: 0.3 seconds or more and less than 2.0 seconds

  The current density at this time is a value exceeding the limit current density. That is, the roughening process is performed with a current value that causes so-called burn plating.

  Further, by setting the treatment time to 0.3 seconds or more and 2.0 seconds or less, for example, if the roughened grains are averaged, the thickness can be formed to 0.05 μm or more and less than 0.26 μm. Preferably, the roughening grain layer is formed to a thickness of 0.05 μm or more and 0.25 μm or less with a treatment time of 0.3 second or more and 1.3 second or less.

  Moreover, it is desirable to add metal elements other than copper (Cu) to the above-mentioned acidic copper plating bath. Examples of metal elements other than copper (Cu) include copper (Cu), iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), chromium (Cr), zinc (Zn), tungsten ( W) and the like, and at least one, preferably two or more of these can be added.

  Specifically, an aqueous solution containing 10 g / L or more and 30 g / L or less of iron sulfate heptahydrate can be used.

  In the roughening copper plating layer forming step S30, a roughening process is performed using the copper plating layer having the predetermined state as a base. Therefore, during the roughening treatment, the non-growth portion of the roughened grains, that is, the roughening is not easily generated. Therefore, a roughened copper plating layer including fine roughened grains having good uniformity is formed. At this time, the difference between the maximum particle size and the minimum particle size of the roughened particles is also reduced.

  As described above, the roughened copper plating layer is formed on the copper plating layer.

(Rust prevention layer forming step S40)
Next, nickel plating treatment S41, zinc plating treatment S42, chromate treatment (trivalent chromium chemical conversion treatment) S43, and silane coupling treatment S44 are performed to form a rust prevention layer on the roughened copper plating layer. The rust preventive layer forming step S40 is performed. Such a rust prevention layer is also called a post-treatment plating layer. In addition, a water washing process is performed between each process.

  For the nickel plating treatment S41, for example, an aqueous solution containing 280 g / L to 320 g / L of nickel sulfate hexahydrate, 40 g / L to 50 g / L of nickel chloride, and 40 g / L to 60 g / L of boric acid is used. be able to. Thereby, a nickel plating layer is formed on the roughened copper plating layer. At this time, a nickel plating layer made of a nickel alloy may be formed by adding a compound containing other metal elements such as cobalt.

  For the galvanizing treatment S42, for example, an aqueous solution containing zinc sulfate of 80 g / L to 120 g / L and sodium sulfate of 60 g / L to 80 g / L can be used. Thereby, a zinc plating layer is formed on the nickel plating layer. At this time, a compound containing another metal element may be added to form a galvanized layer composed of a zinc alloy.

  Thereafter, a chromate treatment S43 is used to form a chromate treatment layer (trivalent chromium conversion treatment layer) on the zinc plating layer using a trivalent chromium type reaction chromate solution. Further, as the silane coupling treatment S44, a silane coupling treatment layer is formed on the chromate treatment layer using a silane coupling liquid.

  Each time is adjusted under the above conditions, for example, a nickel plating layer is formed to a thickness of 10 nm to 50 nm, a zinc plating layer is formed to a thickness of 1 nm to 10 nm, and a chromate treatment layer is 1 nm to 10 nm. The thickness is formed. Further, the silane coupling treatment layer is formed very thin.

  As described above, the nickel plating layer, the zinc plating layer, the chromate treatment layer, and the silane coupling treatment layer are formed in this order on the roughened copper plating layer, and the rust prevention layer is formed with a thickness of 11 nm to 70 nm. The

  Moreover, the roughening foil as composite copper foil which concerns on this embodiment is manufactured by the above.

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

(Recrystallization annealing process (CCL process))
First, the composite copper foil according to the present embodiment is cut into a predetermined size and bonded to an FPC base material made of, for example, a polyimide resin film to form a CCL (Copper Clad Laminate). That is, an adhesive such as an epoxy-based adhesive provided on the surface of the base material is cured by heat treatment, and the roughened surface having the roughened copper plating layer of the composite copper foil and the base material are adhered and bonded. To do. The heating temperature and time can be appropriately selected according to the curing temperature of the adhesive or the base material, for example, at a temperature of 150 ° C. or more and 400 ° C. or less, 1 minute or more and 120 minutes or less, 0.5 MPa or more and 3.0 MPa. Bonding can be performed while applying the following pressure.

  As described above, the heat resistance of the rolled copper foil included in the composite copper foil is adjusted according to the heating temperature at this time. Therefore, the rolled copper foil that has been work-hardened in the final cold rolling step is softened by the above-described heating and tempered to recrystallization. That is, the CCL process of bonding the composite copper foil to the substrate also serves as a recrystallization annealing process for the rolled copper foil of the composite copper foil.

  Thus, in the process until the composite copper foil is bonded to the substrate by the CCL process also serving as the recrystallization annealing process, the rolled copper foil is processed and cured after the final cold rolling process. It can be handled, and deformation such as elongation, wrinkling, and folding can be made difficult to occur when the composite copper foil is bonded to the base material.

  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. Thereby, the rolled copper foil excellent in bending resistance can be obtained.

  On the other hand, the copper plating layer and the roughened copper plating layer on the rolled copper foil are formed to be sufficiently thin so as not to prevent recrystallization of the rolled copper foil. In addition, the copper plating layer itself is relatively easily recrystallized by being formed by the above-described copper plating layer forming step S20. Therefore, it is conceivable that at least a part of the copper plating layer is recrystallized together with the rolled copper foil in this recrystallization annealing step.

  As described above, the bending resistance of the composite copper foil as a whole can be improved.

(Surface machining process)
Next, a surface processing step is performed on the composite copper foil bonded to the substrate. In the surface processing process, for example, a wiring forming process for forming wiring (lead) etc. on the composite copper foil by using a technique such as etching, and a plating process for improving the connection reliability between the wiring and other electronic parts, etc. A surface treatment process for performing a surface treatment and a protective film forming process for forming a protective film such as a solder resist so as to cover a part of the wiring to protect the wiring and the like are performed.

  As described above, the FPC using the composite copper foil according to the present embodiment is manufactured.

  At this time, since the copper plating layer having the above-described predetermined state and the composite copper foil having the roughened copper plating layer with the roughening omission reduced as a base are used, the substrate exposed in the FPC is transparent. The rate remains high. Therefore, an FPC with excellent wiring boundary visibility and easy alignment can be obtained.

<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, the roughened copper plating layer is formed by attaching the roughened grains on the copper plating layer. However, in the step of forming the roughened copper plating layer, the capsule plating process may be further performed. Good. As a result, the roughened grains are covered with the capsule copper plating layer, so-called covering plating layer, and the roughened grains can be grown into bump-like projections, and the dropout of the roughened grains can be suppressed. However, when it is desired to keep the roughened grains fine, the capsule copper plating process is unnecessary.

  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 it decided to manufacture the 3 layer material CCL which bonds together composite copper foil and a base material via an adhesive agent, it bonds directly without using an adhesive agent, and 2 The layer material CCL may be manufactured. When an adhesive is not used, the composite copper foil and the base material may be directly pressure-bonded by heating and pressing. In the case of the two-layer CCL, for example, bonding can be performed at a temperature of 150 ° C. or higher and 400 ° C. or lower while applying a pressure of 1 MPa or higher and 30 minutes or lower and 1 MPa or higher and 10 MPa or lower.

  In the above-described embodiment, the composite copper foil is used for FPC, but the use of the composite copper foil is not limited to this. For example, the negative electrode current collector copper foil of a lithium ion secondary battery, or a plasma display It can also be used for other applications such as electromagnetic wave shields and IC card antennas.

  Further, in the above-described embodiment, a predetermined effect has been found in electrolytic plating using a predetermined organic additive as a method of forming a copper plating layer having a predetermined state as described above. However, other than this, an additive having the same effect as the above-described predetermined organic additive may be used. Or you may form the copper plating layer which has the above predetermined conditions by the formation process etc. of the other copper plating layer different from the above.

  The main point of the present invention is that the roughening omission of the roughened copper plating layer is reduced. In addition, as a configuration that enables this, the copper plating layer of the composite copper foil is in a predetermined state, and in particular, the concave portion that may exist on the surface of the copper plating layer is a predetermined size or less, and the copper plating The layer is configured to be recrystallized in the above-described recrystallization annealing step.

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

(1) Production of rolled copper foil with copper plating layer and roughened foil In order to perform various evaluations, the rolled copper foil with copper plated layer and the roughened foil according to Examples 1 to 9 and Comparative Examples 1 to 11 were produced. .

Example 1
First, the production process of the rolled copper foil with a copper plating layer and the roughened foil according to Example 1 will be described below.

  As the raw foil, a rolled copper foil having a thickness of 11 μm made of tough pitch copper (TPC) was used. Further, when the surface of this rolled copper foil was measured at random at 10 points with a laser microscope, the average value of the depths of the concave portions on the surface was 0.7 μm.

Next, electrolytic degreasing and pickling treatment were performed to clean the surface of the rolled copper foil. As electrolytic degreasing, treatment for 10 seconds was performed 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 . After the rolled copper foil was washed with water, it was immersed in an aqueous solution containing 150 g / L of sulfuric acid at a liquid temperature of 25 ° C. for 10 seconds as pickling. Thereafter, the rolled copper foil was further washed with water.

Next, a copper plating layer having a thickness of 0.1 μm was formed. In this step, 170 g / L of copper sulfate pentahydrate, 70 g / L of sulfuric acid, 30 mg / L of bis (3-sulfopropyl) disulfide (SPS) powder reagent as an organic sulfur compound, and polyethylene glycol as a surfactant 3000 (polyethylene glycol having a molar mass of 3000 g / mol) is 200 mg / L, CU-BRITETH-RIII-C manufactured by Sugawara Eugene Co., Ltd. is used as a leveling agent, 5 ml / L, and hydrochloric acid (HCl aqueous solution) is used as chloride ions. An aqueous solution containing 15 ml / L was used. The plating conditions were set at a liquid temperature of 35 ° C. and a current density of 7 A / dm ² for 10 seconds. Thereafter, the rolled copper foil was washed with water.

  The rolled copper foil with a copper plating layer concerning Example 1 was manufactured by the above.

  Subsequently, a roughened copper plating layer formed by forming roughened grains is formed on the copper plating layer.

First, a roughened copper plating layer corresponding to a thickness of 0.05 μm was formed when averaged. In this step, an aqueous solution containing 100 g / L of copper sulfate pentahydrate, 70 g / L of sulfuric acid, and 20 g / L of iron sulfate heptahydrate was used. The plating conditions were set at a liquid temperature of 30 ° C. and a current density of 60 A / dm ² for 0.5 seconds. Thereafter, the rolled copper foil was washed with water.

  Next, a rust prevention layer is formed by forming a nickel plating layer, a zinc plating layer, a chromate treatment layer, and a silane coupling treatment layer in this order on the roughened copper plating layer.

First, a nickel plating layer having a thickness of 20 nm was formed. In this step, an aqueous solution containing nickel sulfate hexahydrate 300 g / L, nickel chloride 45 g / L, and boric acid 50 g / L was used. The plating conditions were set at a liquid temperature of 50 ° C. and a current density of 2 A / dm ² for 5 seconds. Thereafter, the rolled copper foil was washed with water.

Next, a zinc plating layer having a thickness of 7 nm was formed. In this step, an aqueous solution containing 90 g / L of zinc sulfate and 70 g / L of sodium sulfate was used. The plating conditions were set to a liquid temperature of 30 ° C. and a current density of 1.5 A / dm ² for 4 seconds. Thereafter, the rolled copper foil was washed with water.

  Next, a trivalent chromium chemical conversion treatment was performed to form a 5 nm thick chromate treatment layer. Thereafter, the film was immersed in a silane coupling solution containing 5% 3-aminopropyltrimethoxysilane at 25 ° C. for 5 seconds and immediately dried at a temperature of 200 ° C. to form a silane coupling treatment layer.

  The above-mentioned layers are not formed on the surface on which each of the above-described layers is formed, that is, the surface opposite to the surface to be bonded to the polyimide resin film, and a part of the rust-proof layer, that is, nickel plating. A layer, a galvanized layer, and a chromate treatment layer were formed in the same manner as described above.

  Thus, the roughened foil according to Example 1 was manufactured.

(Examples 2-9)
Then, the rolled copper foil with a copper plating layer and roughened foil which concern on Examples 2-9 were manufactured.

  The rolled copper foil with a copper plating layer according to Examples 2 and 3 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.3 μm and 0.6 μm, respectively. Further, the roughened foils according to Examples 2 and 3 were manufactured under the same conditions as in Example 1 described above.

  The rolled copper foil with a copper plating layer according to Example 4 was manufactured under the same conditions as in Example 1 described above. Moreover, the roughened foil according to Example 4 was the same as that of Example 1 described above except that the roughened grains were largely formed by setting the roughened copper plating layer to an average thickness equivalent to 0.11 μm. Produced under the same conditions.

  The rolled copper foil with a copper plating layer according to Examples 5 and 6 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.3 μm and 0.6 μm, respectively. Further, the roughened foils according to Examples 5 and 6 were produced under the same conditions as in Example 4 described above.

  The rolled copper foil with a copper plating layer according to Example 7 was manufactured under the same conditions as in Example 1 described above. Moreover, the roughening foil which concerns on Example 7 is above-mentioned Example 1 except having formed the roughening grain largely by making it equivalent to the thickness of 0.25 micrometer when a roughening copper plating layer is averaged. Produced under the same conditions.

  The rolled copper foil with a copper plating layer according to Examples 8 and 9 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.3 μm and 0.6 μm, respectively. Further, the roughened foils according to Examples 8 and 9 were produced under the same conditions as in Example 7 described above.

(Comparative Examples 1-11)
Next, the rolled copper foil with a copper plating layer and roughened foil which concern on Comparative Examples 1-11 were manufactured.

  The rolled copper foil with a copper plating layer according to Comparative Example 1 was manufactured under the same conditions as in Example 2 described above. Moreover, the roughening foil which concerns on the comparative example 1 was above-mentioned Example 1 except having formed the roughening grain small by making it equivalent to the thickness of 0.03 micrometer when the roughening copper plating layer was averaged. Produced under the same conditions.

  The rolled copper foil with a copper plating layer according to Comparative Example 2 was manufactured under the same conditions as in Example 2 except that the copper plating layer was formed without adding an organic additive. Moreover, the roughened foil which concerns on the comparative example 2 was manufactured on the conditions similar to the above-mentioned comparative example 1.

  The rolled copper foil with a copper plating layer according to Comparative Example 3 was manufactured under the same conditions as in Example 2 described above. Moreover, the roughening foil which concerns on the comparative example 3 was manufactured on the conditions similar to the above-mentioned comparative example 1 except having formed the roughening copper plating layer with the plating solution which does not contain iron sulfate heptahydrate. .

  The rolled copper foil with a copper plating layer according to Comparative Example 4 was manufactured under the same conditions as in Example 1 except that the copper plating layer was not formed. The roughened foil according to Comparative Example 4 was manufactured under the same conditions as in Comparative Example 3 described above.

  The rolled copper foil with a copper plating layer according to Comparative Example 5 was manufactured under the same conditions as in Example 2 described above. Moreover, the roughening foil which concerns on the comparative example 5 is above-mentioned Example 1 except having formed the roughening grain largely by making it equivalent to the thickness of 0.35 micrometer when the roughening copper plating layer is averaged. Produced under the same conditions.

  The rolled copper foil with a copper plating layer according to Comparative Example 6 was manufactured under the same conditions as in Example 2 except that the copper plating layer was formed without adding an organic additive. The roughened foil according to Comparative Example 6 was manufactured under the same conditions as in Comparative Example 5 described above.

  The rolled copper foil with a copper plating layer according to Comparative Example 7 was manufactured under the same conditions as in Example 2 described above. Moreover, the roughening foil which concerns on the comparative example 7 was manufactured on the conditions similar to the above-mentioned comparative example 5 except having formed the roughening copper plating layer with the plating solution which does not contain iron sulfate heptahydrate. .

  The rolled copper foil with a copper plating layer according to Comparative Example 8 was manufactured under the same conditions as in Example 1 except that the copper plating layer was not formed. Further, the roughened foil according to Comparative Example 8 was manufactured under the same conditions as in Comparative Example 5 described above.

  The rolled copper foil with a copper plating layer according to Comparative Example 9 was manufactured under the same conditions as in Example 2 except that the copper plating layer was formed without adding an organic additive. The roughened foil according to Comparative Example 9 was manufactured under the same conditions as in Example 4 described above.

  The rolled copper foil with a copper plating layer according to Comparative Example 10 was manufactured under the same conditions as in Example 2 above. Moreover, the roughening foil which concerns on the comparative example 10 was manufactured on the conditions similar to the above-mentioned Example 4 except having formed the roughening copper plating layer with the plating solution which does not contain iron sulfate heptahydrate. .

  The rolled copper foil with a copper plating layer according to Comparative Example 11 was manufactured under the same conditions as in Example 1 except that the copper plating layer was not formed. The roughened foil according to Comparative Example 11 was manufactured under the same conditions as in Example 4 described above.

(2) Evaluation of rolled copper foil with copper plating layer and roughened foil About rolled copper foil with copper plated layer and roughened foil according to Examples 1-9 and Comparative Examples 1-11 manufactured as described above, Evaluation was performed.

(Surface roughness measurement)
The surface roughness of the rolled copper foil with a copper plating layer according to Examples 1 to 9 and Comparative Examples 1 to 11 was measured.

  The surface roughness measurement for each rolled copper foil with a copper plating layer was carried out by measuring the depth of the recesses present on the surface of the copper plating layer existing in the field of view of magnification 500 times with a laser microscope. In each measurement, the highest part of the measurement length of approximately 200 μm selected at random was used as a reference point, and the degree of depression from the reference point was measured for the concave portion present in the measurement length. . This was repeated 5 times, and the value obtained by dividing the total depth of the recesses by the number of recesses was taken as the recess depth in the copper plating layer.

(Measurement of grain size of roughened grains)
The particle diameters of the roughened grains included in the roughened foils according to Examples 1 to 9 and Comparative Examples 1 to 11 were measured.

The roughened surface of each roughened foil was observed with SEM, and the particle size of 100 roughened grains was measured randomly. Next, these 100 average particle diameters were determined. Moreover, the ratio of the particle size difference between the maximum particle size and the minimum particle size among these 100 particles was calculated by the following equation.
Ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100

  Each numerical value obtained by this is a value including the rust prevention layer, but the influence of the rust prevention layer is negligible because it is sufficiently thin.

(Measurement of roughening area)
The non-growth portion of the roughened grains on the roughened surface of the roughened foils according to Examples 1 to 9 and Comparative Examples 1 to 11, that is, the area of the roughened missing portion was measured.

  The roughened surface of each roughened foil was observed at a magnification of 10,000 times with an SEM, the portion where no roughened grains were observed was determined as the portion where roughening was lost, and the area of the roughened portion was determined from the SEM image. The total sum of the roughened areas in the field of view with a magnification of 10,000 was obtained.

  At this time, the cross-section of each roughened foil was also observed for reference. That is, the cross section of each roughened foil cut perpendicularly to the rolling direction was observed with an SEM using an ion milling device manufactured by Hitachi.

(Measurement of PI transmittance)
The light transmittance of the polyimide (PI) resin films to which the roughened foils according to Examples 1 to 9 and Comparative Examples 1 to 11 were bonded was measured.

  First, the roughened surface of each roughened foil was bonded to both surfaces of the polyimide resin film with a vacuum press machine under conditions of a temperature of 300 ° C. and a pressure of 5 MPa for 15 minutes. At this time, a Pixio 50 μm-thick polyimide resin film manufactured by Kaneka Corporation was used. Both the polyimide resin film and the roughened foil were 100 mm long and 60 mm wide. The bonding conditions were set so that the heat that would cause the roughened foil to be completely annealed and to have dull characteristics was provided, and the recommended conditions of the polyimide resin film manufacturer were satisfied.

  Next, each roughened foil bonded to the polyimide resin film was processed by ferric chloride spray etching. As a result, the roughened foil on both sides of the polyimide resin film was completely removed, and the underlying polyimide resin film was exposed on both sides.

  The transmittance of light at a wavelength of 700 nm was measured for the exposed polyimide resin film using a spectrophotometer UV-1800 manufactured by Shimadzu Corporation. Since the wavelength of the CCD camera used when mounting the FPC is normally 500 nm to 800 nm, 700 nm was selected as the test wavelength. The transmittance of light having a wavelength of 700 nm is preferably 50% or more.

(Copper foil / PI gap measurement)
The clearance gap between the roughening foil in the polyimide resin film which bonded the roughening foil which concerns on Examples 1-9 and Comparative Examples 1-11 was measured.

  Under the same conditions as described above, each roughened foil was bonded to both sides of the polyimide resin film, and a cross section cut with an ion milling device manufactured by Hitachi Ltd. was observed with an SEM. Between the observation width of 200 μm on one arbitrarily selected bonding surface, the number of gaps having a size that can be visually recognized at a magnification of 10,000 times was counted. The number of gaps is preferably 2 or less.

(Measurement of peel strength)
The peeling strength of the roughening foil in the polyimide resin film which bonded the roughening foil which concerns on Examples 1-9 and Comparative Examples 1-11 was measured, and the adhesiveness of roughening foil and a polyimide resin film was evaluated. According to the following measurement method, it can be said that the higher the peel strength, the higher the adhesion.

  That is, each roughened foil was bonded on both surfaces of the polyimide resin film under the same conditions as described above. Next, a masking tape having a width of 1 mm was applied to the upper surface of the roughened foil on the rolled copper foil side on one bonding surface, and a masking tape was bonded to the entire surface of the rolled copper foil on the other bonding surface. In this state, the treatment was performed by ferric chloride spray etching. Thereby, in one bonding surface, the roughening foil other than the area | region masked with the masking tape was removed, and it became the state which the base polyimide resin film exposed. On the other surface side where the entire surface is protected by the masking tape, the roughened foil remains without being etched.

  The polyimide resin film on which the roughened foil was bonded and a part thereof was exposed was immersed in 3% diluted sulfuric acid at 50 ° C. for 1 hour, and the peel strength before and after immersion was measured. In this measurement, the force required to peel off the roughened foil that had been etched to a width of 1 mm from the polyimide resin film at an angle of 90 ° was measured as the peel strength. Moreover, the ratio (%) of the peel strength after immersion (sulfuric acid immersion) with respect to the peel strength before immersion (normal state) was calculated, and chemical durability, that is, how much the peel strength decreased after immersion was evaluated. The peel strength in the normal state is preferably 1.0 N / nm or more, and the chemical durability is preferably 80% or more.

(Evaluation of boundary visibility)
The boundary visibility of the roughening foil in the polyimide resin film which bonded the roughening foil which concerns on Examples 1-9 and Comparative Examples 1-11 was evaluated.

  Each roughened foil was bonded to both surfaces of the polyimide resin film under the same conditions as described above. Next, a masking tape having a width of 1 mm was applied to the upper surface of the roughened foil on the side of the rolled copper foil on one bonding surface, and the entire surface of the rolled copper foil was left exposed on the other bonding surface. In this state, the treatment was performed by ferric chloride spray etching. Thereby, in one bonding surface, the roughening foil other than the area | region masked with the masking tape was removed, and it became the state which the base polyimide resin film exposed. On the other side, the roughened foil was completely removed, and the underlying polyimide resin film was exposed.

  The side of the roughened foil that had been etched to a width of 1 mm was taken as the back surface, and the side on which the polyimide resin film was exposed was observed with a metallographic microscope. Thus, when the polyimide resin film was seen through, the visibility of the edge of the roughened foil having a width of 1 mm, that is, the boundary between the roughened foil and the polyimide resin film was evaluated. Whether or not the density of the boundary can be clearly confirmed by visual observation was used as a criterion for determining whether or not the alignment by the CCD camera is possible when the FPC is mounted. If it could be confirmed clearly, it was judged as good (◯), and if it could not be confirmed, it was judged as impossible (×).

  In addition, the judgment criteria etc. in the above evaluation are established as a rough standard for the pass / fail judgment in this embodiment, and in each evaluation, depending on the form of the roughened foil or FPC that is actually the product, the required use, etc. The range of suitability can be changed as appropriate.

(3) Evaluation results of rolled copper foil with copper plating layer and roughened foil In Table 1 below, each of the rolled copper foil with copper plated layer and the roughened foil according to Examples 1-9 and Comparative Examples 1-11 An evaluation result is shown.

  As Table 1 showed, in the rolled copper foil with a copper plating layer and roughened foil which concern on Examples 1-9, all the numerical values were in the above-mentioned range. On the other hand, in the rolled copper foil with copper plating layer and the roughened foil according to Comparative Examples 1 to 11, one of the numerical values was out of the above range. In the roughened foil according to Comparative Example 9, the ratio of the average particle diameter and the particle diameter difference of the roughened grains is within a predetermined range, but the roughened omission, the gap with the polyimide resin film, the chemical durability, The boundary visual recognition strength is out of the predetermined range. This is presumably because no organic additive was added to the plating solution of the copper plating layer serving as the base of the roughened copper plating layer.

  Moreover, the roughening omission area showed the tendency which became large, so that the recessed part in a copper plating layer was deep, and the average particle diameter of the roughening grain with which the roughening copper plating layer was equipped was small.

  Moreover, the tendency for the transmittance | permeability of a polyimide resin film to fall, so that the average particle diameter of the roughening particle | grains with which a roughening copper plating layer is provided became large was seen.

  In addition, the number of gaps between the roughened foil and the polyimide resin film tends to increase as the ratio of the particle size difference of the roughened grains provided in the roughened copper plating layer increases, and as the roughening missing area increases. It was seen.

  Moreover, the tendency for the peeling strength in a normal state to fall was seen, so that the average particle diameter of the roughening grain with which the roughening copper plating layer is provided is small. Moreover, the chemical durability tended to decrease as the number of gaps between the roughened foil and the polyimide resin film increased.

  Further, the boundary visibility of the roughened foil tends to decrease as the average particle diameter of the roughened grains provided in the roughened copper plating layer increases and as the number of gaps between the roughened foil and the polyimide resin film increases. Was seen.

(SEM observation results)
In FIG. 2, FIG. 3, the observation result of the surface and cross section by SEM of the roughening foil which concerns on Example 8 and Comparative Example 4 is shown. The upper part of FIG. 2 is Example 8, and the lower part is Comparative Example 4. Moreover, in the surface observation of FIG. 2, the SEM image which varied the magnification about each roughening foil was acquired. Of these, the area of roughening omission in Table 1 described above is determined based on the SEM photograph with a magnification of 10,000 in the center.

  In Example 8 shown in the upper part of FIG. 2, the entire surface of the copper plating layer is covered with roughened grains, and no roughening is observed in the field of view in these SEM images. On the other hand, in Comparative Example 4 shown in the lower part of FIG. 2, it is understood that there is no particulate outline due to the roughened grains, and there is a portion where the underlying copper plating layer is exposed. This is a non-growth portion of the roughened grains, that is, a roughened missing portion.

  Moreover, the SEM image of the cross section of these roughening foil is shown by FIG. In Example 8 on the left side of FIG. 3, the roughened grains are in a continuous state without interruption for a predetermined distance, and no roughening omission is recognized even by the SEM image of the cross section. On the other hand, in Comparative Example 4 on the right side of FIG. 3, the roughening grains are partly interrupted and the copper plating layer is exposed, and it is recognized that roughening omission has occurred in the SEM image of the cross section.

Claims (8)

Rolled copper foil,
A copper plating layer formed on at least one side of the rolled copper foil;
A roughened copper plating layer formed on the copper plating layer and including roughening grains having an average particle size of 0.05 μm or more and 0.30 μm or less, and
The ratio of the particle size difference between the maximum particle size and the minimum particle size of the roughened particles is 65% or less,
In the cut surface that cuts the roughened copper plating layer in the thickness direction, the roughened grains are continuously connected on the copper plating layer without interruption over a distance of 20 μm or more. Composite copper foil.
However, the ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100. Rolled copper foil,
A copper plating layer formed on at least one side of the rolled copper foil;
A roughened copper plating layer formed on the copper plating layer and including roughening grains having an average particle size of 0.05 μm or more and 0.30 μm or less, and
The ratio of the particle size difference between the maximum particle size and the minimum particle size of the roughened particles is 65% or less,
A composite copper foil characterized in that, in a scanning electron microscope, the area of the non-formed portion of the roughened grains existing in a field of view of 10,000 times is 5 μm ² or less.
However, the ratio of particle size difference (%) = (1−minimum particle size / maximum particle size) × 100. 3. The composite copper foil according to claim 1, wherein when a recess is present on the surface of the copper plating layer, an average value of the depth of the recess is 0.60 μm or less. The copper plating layer is
It forms using the copper plating liquid which added the organic sulfur compound which has a mercapto group, surfactant, a leveling agent, and a chloride ion, The Claim 1 characterized by the above-mentioned. Composite copper foil. 5. The composite copper foil according to claim 1, which has a thickness of 0.05 μm or more and 0.25 μm or less when the roughened copper plating layer is averaged. The composite copper foil according to claim 1, further comprising a rust prevention layer having a thickness of 11 nm to 70 nm on the roughened copper plating layer. A nickel plating layer, a zinc plating layer, a chromate treatment layer, and a silane coupling treatment layer are formed in this order on the roughened copper plating layer, and a rust prevention layer having a thickness of 11 nm to 70 nm is provided. The composite copper foil according to any one of claims 1 to 6. Forming a copper plating layer on at least one side of the rolled copper foil;
Forming a roughened copper plated layer containing roughened grains having an average particle size of 0.05 μm or more and 0.30 μm or less on the copper plated layer;
In the step of forming the copper plating layer,
The manufacturing method of the composite copper foil characterized by forming the said copper plating layer using the copper plating liquid which added the organic sulfur compound which has a mercapto group, surfactant, a leveling agent, and a chloride ion.