JP2014152343A - Composite copper foil and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light transmissivity of a substrate while keeping flex resistance.SOLUTION: A composite copper foil comprises rolled copper foil and a copper plated layer of a thickness of 0.05-0.5 μm formed on at least one side of the rolled copper foil. When concave parts are present in the copper plated layer, the average value of depths of the concave parts is 0.5 μm or smaller.

Description

  The present invention relates to a composite copper foil having a 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. 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 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. 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 improved by recrystallization annealing of the rolled copper foil by heating at the time of bonding to the base material.

  Moreover, in order to improve adhesiveness with a base material, a roughening copper plating layer may be provided in the at least single side | surface of rolled copper foil. At this time, for example, after a copper plating layer is provided on a rolled copper foil and smoothed, a roughened copper plating layer is formed (for example, Patent Documents 1 and 2).

JP 2004-238647 A JP 2006-155899 A

  In a composite copper foil in which a copper plating layer is formed on a rolled copper foil, sufficient bending resistance may not be obtained. This is considered to be an influence of a copper plating layer having a crystal structure different from that of the rolled copper foil. For this reason, it is preferable to form the copper plating layer as thin as possible.

  However, when the copper plating layer is thinned, the roughened copper plating layer may grow abnormally. If there is such an abnormally grown portion in the composite copper foil bonded to the base material, the light transmittance in the base material is lowered. The electronic component and the like mounted on the FPC and the FPC are aligned, for example, through the base material. For this reason, if the light transmittance in the base material is lowered, the alignment becomes difficult.

  The objective of this invention is providing the manufacturing method of the composite copper foil and composite copper foil which can raise the transmittance | permeability of the light in a base material, maintaining bending resistance.

According to a first aspect of the invention,
Rolled copper foil,
Formed on at least one surface of the rolled copper foil, and a copper plating layer having a thickness of 0.05 μm or more and 0.5 μm or less, and
When the concave portion exists on the surface of the copper plating layer, a composite copper foil having an average depth of the concave portion of 0.5 μm or less is provided.

According to a second aspect of the invention,
After heat treatment at 250 ° C for 5 minutes,
The composite copper foil according to the first aspect, wherein the number of crystal grains having a maximum diameter of 2.0 μm or more in the copper plating layer is 1 or more and 150 or less in a field of view of 3500 times that of a scanning electron microscope. Provided.

According to a third aspect of the invention,
A roughened copper plating layer is provided on the copper plating layer,
The composite copper foil as described in the 1st or 2nd aspect whose maximum height of the said roughening copper plating layer is 3.0 micrometers or less is provided.

According to a fourth aspect of the invention,
When the roughened copper plating layer is averaged, the composite copper foil according to the third aspect, which is equivalent to a thickness of 0.11 μm to 1.98 μm, is provided.

According to a fifth aspect of the present invention,
The roughened copper plating layer is
When averaged, a roughened grain layer corresponding to a thickness of 0.66 μm or more and 1.1 μm or less,
A composite copper foil according to the third or fourth aspect is provided, wherein a capsule copper plating layer having a thickness of 0.15 μm or more and 0.88 μm or less is formed in this order on the copper plating layer.

According to a sixth aspect of the present invention,
The composite copper foil in any one of the 3rd-5th aspect provided with the rust prevention layer whose thickness is 11 nm or more and 35 nm or less on the said roughening copper plating layer is provided.

According to a seventh aspect of the present invention,
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, and third to third rust prevention layers having a thickness of 11 nm to 35 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,
Formed on at least one surface of a rolled copper foil, and having a step of forming a copper plating layer having a thickness of 0.05 μm or more and 0.5 μm or less,
In the step of forming the copper plating layer,
Provided is a method for producing a composite copper foil using an organic sulfur compound having a mercapto group, a surfactant, and a copper plating solution to which chloride ions are added.

According to a ninth aspect of the present invention,
In the step of forming the copper plating layer,
Current density is 5A / dm ² or more 30A / dm less than ^2, the production method of the composite copper foil according to the eighth embodiment of the liquid temperature to perform electroplating under the following conditions 50 ° C. or higher 15 ℃ is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the composite copper foil and composite copper foil which can raise the light transmittance in a base material is maintained, maintaining bending resistance.

It is a flowchart which shows the manufacturing process of the composite copper foil which concerns on one Embodiment of this invention. It is a schematic diagram of the sliding bending test apparatus which measures the bending resistance of the composite copper foil which concerns on the Example and comparative example of this invention. (A) is the surface observation photograph of the roughening foil which concerns on Example 10 of this invention, (b) is the surface observation photograph of the roughening foil which concerns on the comparative example 7, (b) The lower stage is a comparative example especially In FIG. (A) is a surface observation photograph of the rolled copper foil with a copper plating layer according to Reference Example 1, (b) is a surface observation photograph of the rolled copper foil with a copper plating layer according to Reference Example 2, (a), The upper part of (b) shows before heat treatment, and the lower part shows after heat treatment, respectively. It is a schematic diagram of the composite copper foil which concerns on a prior art, (a) is a case where a thin copper plating layer is provided, (b) is a case where a thick copper plating layer is provided. It is a schematic diagram explaining the subject which arises by bonding of the composite copper foil which concerns on a prior art, and the base material of FPC.

<Knowledge obtained by the present inventors>
As described above, a roughened copper plating layer may be formed on at least one side of the rolled copper foil for FPC in order to improve the adhesion of the FPC to the base material. At that time, for example, a copper plating layer is formed on a rolled copper foil to smooth the surface, and then a roughened copper plating layer is formed.

  In the composite copper foil in which the copper plating layer is formed on the rolled copper foil, it is difficult to obtain sufficient bending resistance. This is considered because the copper plating layer has a different crystal structure from the rolled copper foil. Therefore, in order to obtain a composite copper foil having sufficient bending resistance, it is desirable to make the copper plating layer as thin as possible. By thinning the copper plating layer, the plating time can be shortened and the productivity can be improved.

  However, when the copper plating layer is thinned, abnormal growth of the roughened copper plating layer occurs, and the surface of the roughened copper plating layer may be uneven. When such a composite copper foil is bonded to a base material, the unevenness of the roughened copper plating layer is transferred to the surface of the base material, or the convex portion of the roughened copper plating layer that has digged into the base material is the composite copper foil. May remain even after etching is removed. Thus, when the unevenness | corrugation of a roughening copper plating layer is transcribe | transferred on the surface of a base material, the transmittance | permeability of a base material may fall.

  For example, when an electronic component is mounted on an FPC, even if an attempt is made to align the electronic component and the FPC through such a base material, the transparency of the base material is low, so the visibility is poor and the alignment is difficult. It may become.

  As a result of intensive studies, the present inventors have found that when the copper plating layer is thin, there may be a recess on the surface of the copper plating layer, and by making this recess below a predetermined depth, the copper plating layer is thin. In both cases, it was found that the abnormal growth of the roughened copper plating layer can be suppressed.

  In addition, the present inventors recrystallized the copper plating layer at the time of heating in bonding with the base material, and at least if the copper plating layer is sufficiently thin, the overall bending resistance of the composite copper foil is improved. I found out that it is possible.

  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 this embodiment is formed on at least one surface of 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 the rolled copper foil. A copper plating layer. Moreover, the composite copper foil which concerns on this embodiment is equipped with a roughening copper plating layer and a rust prevention layer in this order on a 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 a rolled copper having 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. It is a foil. 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. The copper plating layer according to the present embodiment has a thickness of, for example, 0.05 μm or more and 0.5 μm or less. In addition, the thickness of the copper plating layer can be expressed as a thickness equivalent to 0.08 g / m ² or more and 0.8 g / m ² or less in terms of plating amount.

  By setting the thickness of the copper plating layer to, for example, 0.05 μm or more, it becomes easy to uniformly apply the roughened copper plating on the copper plating layer. In consideration of the net thickness of the roughened copper plating layer described later, the upper limit of the copper plating layer is set to, for example, 0.5 μm or less as a thickness corresponding to this.

  Moreover, when a recessed part exists in the surface of a copper plating layer, the average value of the maximum diameter of a recessed part is 5 micrometers or less, and the average value of the depth of a recessed part is 0.5 micrometer or less, Preferably it is 0.3 micrometer 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.

Moreover, the copper plating layer which concerns on this embodiment is comprised so that it may recrystallize by the heat processing in bonding with a base material. Specifically, after heat treatment at 250 ° C. for 5 minutes, the number of crystal grains having a maximum diameter (major axis) of 2.0 μm or more in the copper plating layer is 3500 times that of a scanning electron microscope (SEM). Within the field of view, that is, for example, within 953 μm ² field of view, the number is 1 or more and 150 or less. Here, the crystal grain shape of the copper plating layer can be an irregular shape rather than a spherical shape, for example, and the crystal grain diameter is defined as the maximum diameter.

  Thus, the method of obtaining the copper plating layer which makes the size of the surface recessed part below a predetermined value, and causes recrystallization by heat processing is mentioned later.

(Outline of roughened copper plating layer)
The roughened copper plating layer with which the composite copper foil is provided is a layer formed of roughened grains formed on the copper plating layer and mainly 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), tin (Sn), zinc (Zn), It is a metal particle having a diameter of about 1 μm and containing at least one type, preferably two or more types of tungsten (W).

The thickness of the roughened grain layer of the roughened copper plating layer is, for example, 1.0 g / m ² or more and 10 g / m ² or less, preferably 2.3 g / m ² or more and 8.2 g / m in terms of plating amount. It is equivalent to a thickness of less than ² . This is equivalent to a thickness of not less than 0.11 μm and not more than 1.1 μm, preferably not less than 0.25 μm and less than 0.90 μm, assuming that the roughened grain layer having irregularities by each roughened grain is averaged.

In addition, for the purpose of growing the roughened grains into bump-shaped protrusions and further enlarging them, a capsule plating layer, so-called a covering plating layer, may be formed so as to cover the roughened grains. Moreover, when the thickness of the roughened grain layer is relatively thick, for example, 6.0 g / m ² or more and 10 g / m ² or less, that is, 0.66 μm or more and 1.1 μm or less, the dropping of the roughened grains is suppressed. For the purpose, a capsule plating layer may be formed.

The capsule plating layer is formed by copper plating or the like. For example, the capsule plating layer is equivalent to a thickness of 1.4 g / m ² or more and 8.0 g / m ² or less, that is, a thickness of 0.15 μm or more and 0.88 μm or less. It is. By setting the thickness of the capsule plating layer in such a range, it is possible to suppress the falling off of the roughened grains and to prevent the roughened grains from being filled with the capsule plated layer and becoming non-granular.

  Thus, the roughened copper plating layer is mainly composed of a roughened grain layer, or may be provided with a capsule plating layer. Accordingly, the lower limit of the thickness when the roughened copper plating layer having irregularities is averaged is, for example, 0.11 μm which is the minimum value when the capsule plating layer is not provided. For example, when the capsule plating layer is provided, the upper limit is 1.98 μm obtained by adding 1.1 μm and 0.88 μm which are the maximum values of the respective layers.

  Moreover, as a thickness when the roughened copper plating layer is averaged, a more preferable minimum value of 0.25 μm may be set as the lower limit. Moreover, it is good also considering less than 1.78 micrometers which added 0.90 micrometer and 0.88 micrometer which are more preferable maximum values as an upper limit.

  The maximum height Ry of the roughened copper plating layer is 3.0 μm or less. The maximum height Ry is a specified value of the surface roughness according to JIS B0601: 2001. From the roughness curve obtained by the surface roughness measurement, the difference between the highest peak and the lowest valley within the reference length is observed. Thereby, the difference of the unevenness | corrugation which a roughening copper plating layer has can be known.

  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. At this time, by setting the thickness of the roughened copper plating layer within the above-mentioned predetermined range, the plating time is kept within the predetermined range while improving the productivity while obtaining adhesion with the base material by the anchor effect. Can do. By not excessively thickening the roughened copper plating layer, it is easy to maintain the bending resistance of the composite copper foil as a whole.

(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 0.3 g / m ² or less in terms of plating amount, that is, a thickness of 11 nm or more and 35 nm or less.

  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 rust preventive layer within the above-mentioned predetermined range, while obtaining sufficient heat resistance and chemical resistance, it is possible to prevent the etching residue from occurring and to prevent root residue and the like from occurring. it can.

  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.

(Operation of composite copper foil)
The effect | action of the composite copper foil comprised as mentioned above is demonstrated below.

  As described above, if the copper plating layer that is the base of the roughened copper plating layer is thin, abnormal growth may occur in the roughened copper plating layer.

  The present inventors have found that the abnormal growth of the roughened copper plating layer 130 exists on the surface of the copper plating layer 120 formed on the rolled copper foil 110, as in the composite copper foil 100 shown in FIG. It was found out that it was happening around the recess 120d. According to the present inventors, when the recess 120d existing on the surface of the copper plating layer 120 exceeds the predetermined size, abnormal growth of the roughened copper plating layer is likely to occur.

  Further, according to the present inventors, the recess 120d on the surface of the copper plating layer 120 is the one in which the oil pits originally present on the surface of the rolled copper foil 110 remain without being completely filled with the copper plating layer 120. It is believed that there is. 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.

  When roughening copper plating is performed, abnormal growth of the roughened copper plating layer 130 occurs due to abnormal precipitation in which the amount of plating deposited around the recess 120d is more concentrated than other portions. In the portion where the abnormal growth has occurred, for example, the roughened copper plating layer 130 has a convex shape protruding more than the others. Such convex portions are, for example, roughened coarse particles having a size three times or more than the average size of coarse particles in other portions, and the anticorrosive layer 140 formed thereon. Consists of. On the other hand, in the composite copper foil 200 of FIG. 5B, a thick copper plating layer 220 is formed on the rolled copper foil 210, and a flat roughened copper plating layer 230 with relatively roughened grains is obtained. The anticorrosive layer 240 formed on is provided.

  As shown in FIG. 6, after the composite copper foil 100 is bonded to the FPC base material 300 (FIGS. 6A and 6B), a part thereof is removed by etching or the like, and the wiring of the FPC is performed. (Lead) 150 (FIG. 6C). However, when the composite copper foil 100 having the abnormally grown portion as described above on the roughened copper plating layer 130 is bonded to the base material 300, the unevenness of the composite copper foil 100 is transferred to the base material 300, and the composite copper by etching Even after the removal of the foil 100, it remains on the substrate 300. Thereby, the light transmittance in the base material 300 is lowered.

  Further, the convex abnormally grown portion of the roughened copper plating layer 130 is in a state of being bitten into the base material 300. For this reason, even after the removal of the composite copper foil 100 by etching, the convex roughened copper plating layer 130 and the anticorrosive layer 140 formed thereon become a residue while biting into the substrate 300, so-called A root residue (copper residue) 130r is likely to occur. If there is such a root residue 130r, the light transmittance in the substrate 300 further decreases.

  An electronic component or the like is mounted on the FPC in which the wiring 150 is formed. At this time, alignment between the wiring 150 and the electronic component or the like is performed. At the time of alignment, for example, an electronic component or the like is disposed so as to face the wiring 150 on the substrate 300. Then, light is applied from the side opposite to the wiring 150 of the base material 300, and the wiring 150 is aligned with the electronic component or the like through the base material 300. As described above, when the light transmittance in the substrate 300 is lowered, the visibility is lowered, and the position of the wiring 150 may not be confirmed.

  Further, when the composite copper foil 100 having the abnormally grown portion in the roughened copper plating layer 130 is bonded to the base material 300, bubbles, that is, voids 300v may be generated between the composite copper foil 100 and the base material 300. (FIG. 6B). Such voids 300v are likely to occur when bonding is performed by a technique called lamination. Thereby, the adhesiveness of the composite copper foil 100 and the base material 300 may fall. Further, the FPC in which the void 300v is generated may be handled as a defective product due to a poor appearance.

  In order to solve the problems as described above, the copper plating layer according to the present embodiment is configured such that the size of the concave portion on the surface is equal to or smaller than a predetermined value and causes recrystallization by heat treatment.

  That is, in this embodiment, even if the copper plating layer included in the composite copper foil is thin, the size of the recesses that may be present on the surface of the copper plating layer is set to a predetermined value or less, so that abnormal growth in the roughened copper plating layer hardly occurs. . Therefore, the unevenness difference of the roughened copper plating layer, that is, the maximum height Ry can be within the predetermined value. Therefore, it can suppress that the unevenness | corrugation of a roughening copper plating layer is transcribe | transferred to a base material, or a root residue arises and the transmittance | permeability of a base material falls.

  Further, as described above, the copper plating layer according to this embodiment is configured to cause recrystallization by heat treatment.

  In the composite copper foil in which the copper plating layer is provided on the rolled copper foil, the present inventors considered that the bending resistance is inferior to the rolled copper foil as the original foil because of the influence of the copper plating layer. . That is, the copper plating layer originally has a different crystal structure from the rolled copper foil. Further, unlike the rolled copper foil, it is considered that the copper plating layer hardly recrystallizes at the heat treatment temperature at the time of bonding with the base material.

  Therefore, as described above, the copper plating layer is formed to be sufficiently thin and recrystallized when bonded to the base material. Thereby, while rolling copper foil recrystallizes and it comprises bending resistance, the bending resistance of copper plating layer itself can also be improved. After recrystallization, the crystal grains in the copper plating layer become coarse. Therefore, by defining the number of coarse crystal grains in the copper plating layer after the heat treatment as described above, the recrystallized copper plating layer can be defined. Although there is no upper limit to the number of coarse crystal grains, a reasonable numerical value is set as a temporary upper limit for the maximum number obtained in the copper plating layer forming method described later.

  Thus, the bending resistance as a whole of composite copper foil improves by recrystallizing a copper plating layer.

(2) Manufacturing method of composite copper foil The present inventors conducted earnest research in order to form the copper plating layer which satisfy | fills the above-mentioned structural requirements. 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, 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: 1 A / dm ² or more and 30 A / dm ² or less Processing time: 1 second to 20 seconds

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. A more preferable range of the current density is, for example, 5 A / dm ² or more and 30 A / dm ² or less.

  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.

  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 and bis (3-sulfopropyl) disulfide, surfactants such as polyethylene glycol and polypropylene glycol, and hydrochloric acid (HCl aqueous solution). Chloride ions are used in a predetermined combination.

  Specifically, 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 glycol having a molar mass of about 3000 g / mol is 50 mg / L or more and 300 mg / L. Hereinafter, an aqueous solution containing 20 mg / L or more and 80 mg / L or less of hydrogen chloride (HCl) as chloride ions can be used.

These organic additives are used as brighteners and surfactants in the copper plating process. However, the present inventors, by using these organic additives in a predetermined combination, increase the effect of filling the depressions such as oil pits of the rolled copper foil with the copper plating layer, and exist on the surface of the copper plating layer. It has been found that the size of the recess to be obtained can be reduced.

  The present inventors presume 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. In the case where these organic additives are not used, in the thin copper plating layer as in the present embodiment, the effect is obvious from the fact that the size of the recess 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.

  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.

  In addition, in order to acquire the above-mentioned effect, 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. By using any of these in a predetermined concentration and a predetermined composition, the above-described effects relating to the copper plating layer of the present embodiment can be obtained.

  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 treatment S31 and a capsule plating treatment S32 are performed, and a roughening copper plating layer forming step S30 for forming a roughening copper plating layer on the copper plating layer is performed. Note that the capsule plating process S32 may be omitted. In addition, a water washing process is performed between each process.

  First, by roughening treatment S31, 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, and the roughened particles are attached to the surface of the copper plating layer, A roughened grain layer is formed.

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: 0.5 seconds to 10 seconds

  The current density at this time is a value exceeding the limit current density. That is, the roughening process S31 is performed with a current value that causes so-called burn plating.

  Further, by setting the treatment time to 0.5 seconds or more and 10 seconds or less, for example, if the roughened grain layer is averaged, it can be formed to a thickness of 0.11 μm or more and 1.1 μm or less. Preferably, the roughening grain layer may be formed to a thickness of 0.25 μm or more and less than 0.90 μm with a treatment time of 2 seconds or more and 10 seconds or less.

  Moreover, metal elements other than copper (Cu) are added to the above-mentioned acidic copper plating bath. Examples of metal elements other than copper (Cu) include iron (Fe), molybdenum (Mo), nickel (Ni), cobalt (Co), tin (Sn), zinc (Zn), tungsten (W), and the like. These are preferably added in at least one, preferably two or more.

  Specifically, an aqueous solution containing 10 g / L to 30 g / L of iron sulfate heptahydrate and 1 g / L to 2 g / L of sodium molybdate can be used.

  Subsequently, a capsule plating process S32 is performed as necessary, and the roughened grains are covered with a capsule copper plating layer (covered plating layer). Thereby, the roughened grains can be grown into bump-like projections, and the dropout of the roughened grains can be suppressed. In addition, when it is desired to keep the roughened grains fine, the capsule plating process S32 can be omitted.

  In the capsule plating process S32, for example, an electrolytic process using a rolled copper foil as a cathode in an acidic copper plating bath mainly composed of copper sulfate and sulfuric acid is performed to form a capsule 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: 20 ° C. or more and 50 ° C. or less Current density: 1 A / dm ² or more and 20 A / dm ² or less Processing time: 1 second to 20 seconds

  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. Moreover, you may add the predetermined | prescribed organic type additive used by the above-mentioned copper plating process S22 to the above-mentioned acidic copper plating bath.

  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.

  As described above, a rust prevention layer is formed in which 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.

  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 formed by the above-described copper plating layer forming step S20 is also recrystallized by heating in this recrystallization annealing step, and is a crystal having a predetermined number or more of crystal grains having a predetermined size or more as described above. Tempered into an organization. Thereby, the bending resistance of copper plating layer itself can also be improved, and the bending resistance as a whole of composite copper foil 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.

<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 composite copper foil is formed by forming a copper plating layer, a roughened copper plating layer, and a rust prevention layer in this order on the rolled copper foil. Not limited. For example, the composite copper foil may be configured as a rolled copper foil with a copper plating layer. Moreover, the composite copper foil may be configured as a roughened foil. In the above-described embodiment, the roughened foil is formed by forming the copper plated layer, the roughened copper plated layer, and the rust preventive layer in this order on the rolled copper foil, but even if the rust preventive layer is not provided. Good.

  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 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 that require bending resistance, such as electromagnetic wave shields for use and antennas for IC cards.

  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 the above-described predetermined structural requirements. However, in addition to these, 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-mentioned predetermined structural requirements by the formation process of another copper plating layer different from the above, or a recrystallization annealing process.

  The main point of the present invention is that the concave portions that can be present on the surface of the copper plating layer of the composite copper foil are not more than a predetermined size, and that the copper plating layer is recrystallized in the above-described recrystallization annealing step. Is configured to be possible. Further, the unevenness of the unevenness of the roughened copper plating layer is reduced.

  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 6 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 original foil, three rolled copper foils containing 0.01% by mass of tin (Sn) and having a thickness of 11 μm were used. When the bending resistance described later was evaluated for the rolled copper foil, the number of bending was 1.3 million on average after three heat treatments at 250 ° C. for 5 minutes. Moreover, when the surface of this rolled copper foil was measured at random at 10 points with a laser microscope, the average value of the depth of the surface recesses 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 0.05 μm was formed. In this process, 170 g / L of copper sulfate pentahydrate, 70 g / L of sulfuric acid, 40 mg / L of bis (3-sulfopropyl) disulfide as an organic sulfur compound, and polyethylene glycol 3000 (molar mass of 3000 g as a surfactant) An aqueous solution containing 150 mg / L of polyethylene glycol / mol and 50 mg / L of hydrogen chloride (HCl) as a chloride ion 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.

  Then, the roughening copper plating layer formed by forming a roughening grain layer and a capsule plating layer in this order on a copper plating layer is formed.

First, a roughened grain layer corresponding to a thickness of 0.5 μm was formed when averaged. In this step, an aqueous solution containing 50 g / L of copper sulfate pentahydrate, 70 g / L of sulfuric acid, 20 g / L of iron sulfate heptahydrate, and 1 g / L of sodium molybdate was used. The plating conditions were set at a liquid temperature of 30 ° C. and a current density of 40 A / dm ² for 5 seconds. Thereafter, the rolled copper foil was washed with water.

Next, a capsule plating layer having a thickness of 0.3 μm was formed. In this step, an aqueous solution containing 170 g / L of copper sulfate pentahydrate and 70 g / L of sulfuric acid was used. The plating conditions were set at a liquid temperature of 35 ° C. and a current density of 7 A / dm ² for 15 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 5 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 180 ° 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 copper plating layer and the roughened foil according to Examples 2 and 3 were produced under the same conditions as in Example 1 described above. In each plating step, components in the liquid may vary within the above-described predetermined range. Examples 2 and 3 are for reproducibility evaluation of Example 1.

  The rolled copper foil with a copper plating layer according to Examples 4 to 6 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.2 μm. Moreover, the roughening foil which concerns on Examples 4-6 was manufactured on the conditions similar to the above-mentioned Example 1. FIG.

  The rolled copper foil with a copper plating layer according to Examples 7 to 9 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.5 μm. Moreover, the roughening foil which concerns on Examples 7-9 was manufactured on the conditions similar to the above-mentioned Example 1. FIG.

(Comparative Examples 1-6)
Next, the rolled copper foil with a copper plating layer and roughened foil which concern on Comparative Examples 1-6 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 1 except that the thickness of the copper plating layer was 0.03 μm. Moreover, the roughening foil which concerns on the comparative example 1 was manufactured on the conditions similar to the above-mentioned Example 1. FIG.

  The rolled copper foil with a copper plating layer according to Comparative Example 2 was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 0.80 μm. Moreover, the roughening foil which concerns on the comparative example 2 was manufactured on the conditions similar to the above-mentioned Example 1. FIG.

  In the rolled copper foil with a copper plating layer according to Comparative Examples 3 to 6, the copper plating layer was formed without adding organic additives such as organic sulfur compounds and surfactants and hydrochloric acid. The thickness of the copper plating layer was 0.05 μm in Comparative Example 3, 0.20 μm in Comparative Example 4, 0.50 μm in Comparative Example 5, and 0.80 μm in Comparative Example 6. Other than that, it manufactured on the conditions similar to Example 1. FIG. The roughened foils according to Comparative Examples 3 to 6 were manufactured under the same conditions as in Example 1 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 to 9 and Comparative Examples 1 to 6 manufactured as described above, Evaluation was performed.

(Counting the number of crystal grains)
The state of the crystal grains of the rolled copper foil with a copper plating layer according to Examples 1 to 9 and Comparative Examples 1 to 6 was evaluated.

  Each rolled copper foil with a copper plating layer was heat-treated at 250 ° C. for 5 minutes in a nitrogen atmosphere. Such a condition imitates an example of the amount of heat actually received by the rolled copper foil with a copper plating layer and the roughened foil in the CCL process of the flexible printed wiring board in close contact with the substrate.

Then, the backscattered electron (YAG-BSE: YAG-Back-Scattered Electron) image using the YAG crystal | crystallization was image | photographed with the scanning electron microscope (SEM: Scanning Electron Microscopy). From this YAG-BSE image, the number of crystal grains having a maximum diameter of 2.0 μm or more existing in a 953 μm ² visual field range which is a visual field range when observed at 3500 times was measured.

(Surface roughness measurement)
The surface roughness of the rolled copper foil with copper plating layer and the roughened foil according to Examples 1 to 9 and Comparative Examples 1 to 6 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.

  For the surface roughness measurement for each roughened foil, the maximum height Ry (JIS B0601: 2001) was determined by stylus type surface roughness measurement. Thereby, the unevenness | corrugation difference of the roughening copper plating layer which consists of a roughening grain layer and a capsule plating layer is known. The unevenness difference is a value including the antirust layer, but the unevenness difference of the sufficiently thin antirust layer can be ignored.

(Etching property)
The etching properties of the roughened foils according to Examples 1 to 9 and Comparative Examples 1 to 6 were evaluated.

  First, the roughened surface of each roughened foil was bonded to a polyimide resin film having a thickness of 50 μm using a vacuum press machine under conditions of a temperature of 300 ° C. and a pressure of 30 MPa for 10 minutes. Next, a masking tape having a width of 1 mm was attached to the upper surface of each roughened foil on the side of the rolled copper foil, and an etching process was performed for 1 minute by ferric chloride spray etching. Thereby, the roughening foil other than the region masked by the masking tape was removed, and the underlying polyimide resin film was exposed.

  The roughened foil remaining in the width of 1 mm was regarded as a wiring (lead), and both end portions in the width direction were observed from directly above with a SEM at a magnification of 3500 times over a measurement length of 30 mm. At this time, the number of remaining roots whose maximum length of protrusion from the end portion of the roughened foil that was considered as wiring was 10 μm or more was measured. It is preferable that the number of remaining roots is 1 or less. This is because if there are a plurality of root residues having a maximum protrusion length of 10 μm or more, there is a high possibility that the wiring is short-circuited in a normal FPC.

(Flexibility)
The bending resistance of the roughened foils according to Examples 1 to 9 and Comparative Examples 1 to 6 was evaluated. Such evaluation was performed using the sliding bending test apparatus 10 shown in FIG. 2 in accordance with the IPC (American Printed Circuit Industry Association) standard.

  First, a heat treatment was performed at 250 ° C. for 5 minutes in the atmosphere on the test piece 50 in which each roughened foil was cut to a length of 200 mm and a width of 12.5 mm in the rolling direction. Next, as shown in FIG. 2, 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 measurement conditions, the bending radius 10r was 1.5 mm, the stroke 10 s was 10 mm, and the bending speed was 1500 times / minute. Under such conditions, the average values of the number of bendings until each sample piece 50 broke was compared.

(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 to 9 and Comparative Examples 1 to 6 An evaluation result is shown.

  As shown in Table 1, the rolled copper foil with copper plating layer and the roughened foil according to Example 1 satisfied predetermined values in all evaluation results. In addition, with respect to Examples 2 and 3 related to reproducibility evaluation, evaluation results equivalent to those of Example 1 were obtained. It was found that an evaluation result sufficient to obtain a predetermined effect can be obtained within the range of variation in processing conditions.

  For Examples 4 to 9, the predetermined value was satisfied in all the evaluation results. Moreover, Examples 4-6 produced on the same conditions and Examples 7-9 showed the substantially equivalent result.

  On the other hand, in Comparative Example 1 in which the copper plating layer is thinner than the predetermined value, all the evaluation results other than the bending resistance are out of the predetermined value.

  Further, in Comparative Example 2 where the copper plating layer was thicker than the predetermined value, the surface roughness of the copper plating layer and the roughened copper plating layer was reduced, but the number of bendings was reduced, and good bending resistance was not obtained. . Moreover, there is a concern about the deterioration of productivity as a composite copper foil by thickening the copper plating layer.

  Moreover, when forming a copper plating layer, in Comparative Examples 3-6 which did not use an additive, the surface roughness of the copper plating layer and the roughening copper plating layer increased uniformly. In addition, the number of bendings is slightly reduced as compared with a case where a copper plating layer having the same thickness when the copper plating layer is formed using an additive is used. This is considered to be due to the effect of not adding the additive.

(Other evaluation results)
The result of the surface observation by SEM of the roughened foil which concerns on FIG. 3 at Example 10 and the comparative example 7 is shown.

In Example 10 shown in FIG. 3A, the thickness of the copper plating layer is 3.6 g / m ² (equivalent to a thickness of 0.4 μm), and the thickness of the roughened copper plating layer is 8 g / m ² ( The film was manufactured under the same conditions as in Example 1 except that the thickness was equivalent to 0.9 μm. Therefore, the thickness of the rust prevention layer (nickel plating layer, galvanization layer, chromate treatment layer) in Example 10 is 0.2 g / m ² (corresponding to a thickness of 30 nm). Moreover, in Example 10, the depth of the recessed part of the copper plating layer measured in the same manner as the method and procedure of the above-described example was 0.43 μm.

In Comparative Example 7 shown in FIG. 3B, the thickness of the copper plating layer is 3.6 g / m ² (equivalent to a thickness of 0.4 μm), and the thickness of the roughened copper plating layer is 8 g / m ² ( The film was manufactured under the same conditions as in Comparative Example 3 except that the thickness was equivalent to 0.9 μm. That is, in Comparative Example 7, a copper plating layer was formed without using an additive. The thickness of the antirust layer (nickel plating layer, zinc plating layer, chromate treatment layer) in Comparative Example 7 is 0.2 g / m ² (corresponding to a thickness of 30 nm). Moreover, in the comparative example 7, the depth of the recessed part of the copper plating layer measured similarly to the method and procedure of the above-mentioned Example was 0.55 micrometer.

  As shown in FIG. 3, it can be seen that even when the thicknesses of the respective layers are the same, the roughened grains adhere more uniformly in Example 10 than in Comparative Example 7. As described above, the depth of the concave portion of the copper plating layer in Comparative Example 7 is out of the predetermined value, whereas the depth of the concave portion of the copper plating layer in Example 10 is considered to be within the predetermined value. . Moreover, it is thought that the difference in the depth of the recessed part of a copper plating layer is based on whether the additive was used at the time of formation of a copper plating layer.

  Moreover, the abnormal part scattered in the comparative example 7 is shown in the lower stage of FIG.3 (b). As shown in the lower part of FIG. 3 (b), in Comparative Example 7, a depression (A) that was thought to be due to an oil pit of a rolled copper foil that was not completely filled by the formation of the copper plating layer was observed. Moreover, the abnormal precipitation location (B) of the roughening copper plating layer considered to be abnormally grown by it was recognized.

  The YAG-BSE image of the surface of the copper plating layer in the rolled copper foil with a copper plating layer according to Reference Examples 1 and 2 is shown in FIG.

  Reference Example 1 shown in FIG. 4A was manufactured under the same conditions as in Example 1 except that the thickness of the copper plating layer was 1.0 μm. 4A is a YAG-BSE image before heat treatment, and the lower row is a YAG-BSE image after heat treatment at 250 ° C. for 5 minutes.

  Reference Example 2 shown in FIG. 4B was manufactured under the same conditions as Comparative Example 3 described above except that the thickness of the copper plating layer was 1.0 μm. That is, in Reference Example 2, the copper plating layer was formed without using an additive. Note that the upper part of FIG. 4B is a YAG-BSE image before heat treatment, and the lower part is a YAG-BSE image after heat treatment at 250 ° C. for 5 minutes.

  As shown in FIG. 4, the size of the crystal grains of the copper plating layer of the reference example 1 formed using the additive, as in Example 1, particularly after the heat treatment, is determined without using the additive. It turns out that it is overwhelmingly larger than the size of the crystal grain of the formed copper plating layer of the reference example 2. Even when the difference in the size of the crystal grains is seen, it is clear that there is a difference in the bending resistance of the roughened foil.

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 (9)

Rolled copper foil,
Formed on at least one surface of the rolled copper foil, and a copper plating layer having a thickness of 0.05 μm or more and 0.5 μm or less, and
The composite copper foil characterized by having an average depth of the concave portion of 0.5 μm or less when the concave portion is present on the surface of the copper plating layer. After heat treatment at 250 ° C for 5 minutes,
2. The number of crystal grains having a maximum diameter of 2.0 μm or more in the copper plating layer is 1 or more and 150 or less in a field of view of 3500 times that of a scanning electron microscope. Composite copper foil. A roughened copper plating layer is provided on the copper plating layer,
3. The composite copper foil according to claim 1, wherein the roughened copper plating layer has a maximum height of 3.0 μm or less. 4. The composite copper foil according to claim 3, wherein when the roughened copper plating layer is averaged, the thickness is equal to or greater than 0.11 μm and equal to or less than 1.98 μm. The roughened copper plating layer is
When averaged, a roughened grain layer corresponding to a thickness of 0.66 μm or more and 1.1 μm or less,
5. The composite copper foil according to claim 3, wherein a capsule copper plating layer having a thickness of 0.15 μm or more and 0.88 μm or less is formed on the copper plating layer in this order. The composite copper foil according to claim 3, further comprising a rust prevention layer having a thickness of 11 nm to 35 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 35 nm is provided. The composite copper foil according to any one of claims 3 to 6. Formed on at least one surface of a rolled copper foil, and having a step of forming a copper plating layer having a thickness of 0.05 μm or more and 0.5 μm or less,
In the step of forming the copper plating layer,
The manufacturing method of the composite copper foil characterized by using the copper plating solution which added the organic sulfur compound which has a mercapto group, surfactant, and a chloride ion. In the step of forming the copper plating layer,
9. The method for producing a composite copper foil according to claim 8, wherein the electroplating is performed under conditions of a current density of 5 A / dm ² or more and less than 30 A / dm ² and a liquid temperature of 15 ° C. or more and 50 ° C. or less.