JP2014111277A - Rolled copper foil, surface-treated copper foil, and laminate plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolled copper foil, a surface-treated copper foil and a laminate plate which satisfactorily adhere to a resin, and in which the resin after the copper foil has been removed by etching has excellent transparency.SOLUTION: A rolled copper foil is tough pitch copper based on JIS H3100 C1100 or oxygen-free copper based on JIS-C1020. An average value between a mirror reflectance at an incident angle of 20° in a direction parallel to rolling and a mirror reflectance at an incident angle of 20° in a direction perpendicular to rolling is 30 or more.

Description

  TECHNICAL FIELD The present invention relates to a copper foil used in a circuit of a laminated board and a laminated board using the same, and in particular, a rolled copper foil and a surface-treated copper foil suitable for a field where transparency of a resin after etching the copper foil is required. And a laminated board.

Flexible printed wiring boards (hereinafter referred to as FPCs) used as signal wiring for electronic devices are used in parts that bend and connect between circuits in addition to conventional repeated bending as equipment becomes smaller and thinner. Has increased. When electrically connecting the liquid crystal display of the display device, which is an example, and the substrate, the position of the circuit or marker is confirmed with a CCD camera over a resin layer typified by polyimide as the base of the FPC. A method of aligning is widely used. In this method, if the transparency of the resin layer is low, it is difficult to accurately confirm the positions of the circuits and markers over the resin layer, and it is difficult to align the bonding.
Here, since the resin layer of the FPC is obtained by bonding the copper foil and the resin layer and then removing the copper layer by etching, the surface after removing the copper layer is a replica to which the unevenness of the copper foil surface is transferred. ing. Therefore, when the surface of the copper foil on the adhesive surface side with the resin is rough, the surface of the resin layer also becomes rough, and the light is irregularly reflected, thereby lowering the transparency of the resin. As mentioned above, in order to improve the light transmittance of a resin layer, it is necessary to make the adhesive surface with the resin layer of copper foil smooth.

  In general, since the adhesive surface of the copper foil with the resin layer is roughened for the purpose of ensuring adhesive strength, the surface after the roughening treatment is rougher than the surface of the copper foil before the roughening treatment. Becomes larger. For this reason, as a method for reducing the surface roughness, improvement of roughening plating conditions and surface treatment have been studied so far.

  As such a technique, for example, a copper foil having an adhesion layer formed on the copper foil surface from an ion or oxide of chromium and zinc and treated with an aqueous solution containing at least 0.5% silane is disclosed. (Patent Document 1).

JP 2012-39126 A

However, the adhesion strength of the demonstration sample disclosed in Patent Document 1 remains low as compared with a rough copper foil that is a comparative sample. As described above, when the roughened particles are excessively refined, the adhesion strength with the resin layer is lowered, and there is a limit to smoothing by improving the roughening plating. For this reason, it is difficult to achieve both ensuring of the adhesion strength between the resin layer and the copper foil and improving the visibility of the resin layer.
An object of the present invention is to provide a rolled copper foil, a surface-treated copper foil, and a laminate that are excellently bonded to a resin and excellent in transparency of the resin after the copper foil is removed by etching.

  As a result of intensive research, the present inventors smoothed the surface of the rolled copper foil as a base material for rough plating by a predetermined means, and by using the rolled copper foil in which the specular reflectance was controlled within a predetermined range, It has been found that the transparency of the resin after removing the copper foil by etching is improved even when a roughening treatment for obtaining good adhesion with the resin is performed.

  The present invention completed on the basis of the above knowledge is, in one aspect, tough pitch copper standardized to JIS H3100 C1100 or oxygen-free copper standardized to JIS H3100 C1020, and has a specular reflectance with an incident angle of 20 ° in the rolling parallel direction. And a rolled copper foil in which the average value of the mirror reflectivity at an incident angle of 20 ° in the direction perpendicular to the rolling is 30 or more.

  Another aspect of the present invention is a copper foil containing 0.002 to 0.05 mass% of Ag in addition to tough pitch copper specified in JIS H3100 C1100, and having a mirror reflection angle of 20 ° in the rolling parallel direction. This is a rolled copper foil in which the average value of the rate and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling is 30 or more.

  In another aspect of the present invention, there is provided a copper foil containing oxygen-free copper specified in JIS H3100 C1020 and further containing one or more of Ag, Sn and Zr in a total amount of 0.002 to 0.05% by mass. Thus, the rolled copper foil has an average value of 30 or more of the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling.

  In one embodiment of the rolled copper foil according to the present invention, the thickness is 6 to 35 μm.

  In another embodiment of the rolled copper foil according to the present invention, the polyimide film surface is applied to a sample of a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less obtained by laminating the copper foil and a polyimide film having a film thickness of 25 μm. When 180 ° contact bending is performed inside, the number of bendings until the copper foil breaks is 3 or more.

  In another embodiment of the rolled copper foil which concerns on this invention, the frequency | count of bending until the said copper foil fractures | ruptures is 5 times or more.

According to another aspect of the present invention, there is provided a surface-treated copper foil in which roughened particles are formed by a roughening treatment on at least one surface of the rolled copper foil of the present invention, the copper foil being a polyimide resin substrate. Then, the copper foils on both sides are removed by etching, and the printed matter printed with line marks is laid under the exposed polyimide substrate, and the printed matter is passed through the polyimide substrate with a CCD camera. In the observation point-brightness graph, which was prepared by measuring the brightness for each observation point along the direction perpendicular to the direction in which the observed line-shaped mark extends, for the image obtained by the shooting, The difference ΔB (ΔB = Bt−Bb) between the top average value Bt and the bottom average value Bb of the brightness curve generated from the end portion of the mark to the portion where the mark is not drawn is 40 or more. In the observation point-lightness graph, the value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and Bt is defined as t1, and the reference point is Bt from the intersection of the lightness curve and Bt. In the depth range up to 0.1ΔB, the value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and 0.1ΔB is defined by the following equation (1). It is a surface-treated copper foil whose Sv is 3.5 or more.
Sv = (ΔB × 0.1) / (t1-t2) (1)

  In one embodiment of the surface-treated copper foil of the present invention, Sv defined by the formula (1) in the brightness curve is 5.0 or more.

  In still another aspect of the present invention, the present invention provides a laminated plate configured by laminating the rolled copper foil of the present invention and a resin substrate.

  In still another aspect of the present invention, the present invention is a laminated plate configured by laminating the surface-treated copper foil of the present invention and a resin substrate.

  According to the present invention, it is possible to provide a rolled copper foil, a surface-treated copper foil, and a laminate that are excellently bonded to a resin and excellent in transparency of the resin after the copper foil is removed by etching.

It is a schematic diagram which defines Bt and Bb. It is a schematic diagram which defines t1, t2, and Sv. It is a schematic diagram showing the structure of an imaging device and the measuring method of the inclination of a lightness curve in the case of evaluation of the lightness curve inclination.

  Hereinafter, the rolled copper foil which concerns on embodiment of this invention is demonstrated. Unless otherwise specified, “%” represents “mass%”.

(composition)
The rolled copper foil of the present invention has a composition of tough pitch copper standardized to JIS H3100 C1100 or oxygen-free copper standardized to JIS H3100 C1020. The oxygen concentration contained in the rolled copper foil is 0.01 to 0.05% for tough pitch copper, and 0.001% or less for oxygen-free copper.
Moreover, you may contain 0.002-0.05% of 1 or more types from Ag, Sn, and Zr. When an appropriate amount of Ag and / or Sn is added to the rolled copper foil, the bendability and the bendability after forming the FPC are improved, and the handling property is improved by adding Zr. When the total addition amount of one or more of Ag, Sn, and Zr to the rolled copper foil is less than 0.002%, the effect of improving the properties such as bendability, bendability, and handleability cannot be obtained. The value is 0.002%. Furthermore, since Ag is expensive, and Sn and Zr increase in addition concentration, the recrystallization temperature rises and the flexibility after FPC molding may not be sufficiently obtained. Therefore, the total addition concentration is 0. .05% or less.
In addition, since Ag is harder to oxidize than Cu, it can be added in both tough pitch copper and oxygen-free copper melts, and Sn and Zr are easier to oxidize than Cu, so they are added to the oxygen-free copper melt. Is common.

(Form and manufacturing method of rolled copper foil)
The rolled copper foil of the present invention has an average value of 30 or more between the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling. For this reason, the smoothness of the copper foil surface becomes good, and the transparency of the resin after removing the copper foil by etching is good by performing an appropriate roughening treatment to obtain good adhesion with the resin. Become. When the average value of the specular reflectivity at an incident angle of 20 ° in the rolling parallel direction and the specular reflectivity at an incident angle of 20 ° in the direction perpendicular to the rolling is less than 30, the surface is roughened and bonded to the resin, and the copper foil is etched. The transparency of the resin after the removal is deteriorated.
As a factor affecting the specular reflectance in the rolling parallel direction, the presence of oil pits on the surface of the copper foil can be mentioned. The oil pit is observed as a fine streak pattern perpendicular to the rolling direction, and when the streak pattern increases or the groove becomes deep, the light incident in the rolling parallel direction is irregularly reflected and the specular reflectance is lowered. Therefore, in order to achieve the prescribed specular reflectance, it is necessary to suppress the occurrence of oil pits by controlling the oil film equivalent described later. In addition, when rolling the material after recrystallization annealing to finish it to a predetermined thickness, it is usually processed repeatedly by a plurality of rolling passes, but oil pits are more likely to occur during rolling as the degree of processing of the material decreases. It is important to control the oil film equivalent of the final three passes, including the final final rolling pass in the final cold rolling.
Next, as a factor affecting the specular reflectivity in the direction perpendicular to the rolling, the presence of grinding stripes on the rolled work roll transferred to the copper foil surface can be mentioned. As described above, when rolling under conditions that suppress the occurrence of oil pits, the oil film equivalent is small, that is, the oil film thickness between the rolled work roll and the copper foil surface is reduced, and the grinding streaks on the surface of the work roll are on the copper foil surface. It becomes easy to be transferred. At this time, if the irregularities of the grinding stripe become larger, the surface roughness of the copper foil to which the grinding stripe is transferred also becomes larger, so that the light incident in the direction perpendicular to the rolling is irregularly reflected and the specular reflectance is lowered. Therefore, in order to achieve a specified specular reflectance, it is necessary to reduce the surface roughness of a rolled work roll described later.
In addition to the above, since the oil film equivalent becomes smaller and the grinding streaks are easily transferred to the surface of the copper foil when the rolling degree per pass is increased, even if the surface roughness of the work roll is controlled, the surface roughness is sufficiently small. No copper foil can be obtained. Therefore, it is necessary to set the rolling degree to a certain value or less. Specifically, the maximum degree of rolling in one pass in the final cold rolling process is set to 24% or less.

As a manufacturing method of the rolled copper foil of this invention, it is possible to manufacture as follows. In addition, the manufacturing method of the rolled copper foil of this invention is not intended to be limited to the method shown below.
First, a raw material is melted in a melting furnace to obtain a molten metal having a desired composition. Then, this molten metal is cast into an ingot. Thereafter, hot rolling, cold rolling, and annealing are appropriately performed to finish a foil having a predetermined thickness. After the heat treatment, surface pickling, polishing, or the like may be performed in order to remove the surface oxide film generated during the heat treatment. In the final cold rolling, the material after the heat treatment is repeatedly passed through a rolling mill to be finished to a predetermined thickness. In the method for producing rolled copper foil of the present invention, the oil film equivalent (final pass oil film equivalent) in the final rolling pass of the final cold rolling step is 18000 or less, and the oil film equivalent (final oil film before the final one pass) in the rolling pass immediately before the final rolling pass. Equivalent) is 16000 or less, and the oil film equivalent (oil film equivalent before the final two passes) in the rolling pass immediately before is 15000 or less.
Here, the oil film equivalent is defined by the following equation.
Oil film equivalent = {(rolling oil viscosity [cSt]) × (sheet feeding speed [mpm] + roll peripheral speed [mpm])} / {(roll biting angle [rad]) × (yield stress of material [kg / mm ² ])}
The rolling oil viscosity [cSt] is a kinematic viscosity at 40 ° C.
In order to control the oil film equivalent, a known method such as using a low-viscosity rolling oil or slowing the sheet passing speed may be used.
By controlling the oil film equivalent, deformation of the material surface is constrained by the roll, and an increase in surface roughness accompanying a change in thickness due to rolling can be suppressed. By controlling the oil film equivalent immediately before the final rolling pass to increase the specular reflectivity, the specular reflectivity after the final pass can be controlled within a desired range. If the specular reflectance is low just before the final pass, even if the material surface is smoothed in the final pass, the deep irregularities formed up to the previous pass remain, and the desired specular reflectivity cannot be obtained.

  In addition, when the oil film equivalent is small, the unevenness on the surface of the rolling roll used for rolling is easily transferred to the material surface, so the surface of the rolling roll needs to be smooth. For this reason, as for the rolling roll used with the manufacturing method of the rolled copper foil of this invention, average roughness Ra when measured to the direction parallel to the rotating shaft of a roll is 0.01-0.08 micrometer, More preferably, it is 0.01. ˜0.06 μm. When the surface roughness is larger than this, the irregularities on the roll surface are easily transferred to the material surface, and it becomes difficult to obtain the desired specular reflectance particularly in the direction perpendicular to the rolling.

  Furthermore, if the degree of rolling process per rolling in the final cold rolling is increased, the oil film equivalent is reduced, and the unevenness on the surface of the rolling roll is easily transferred to the material surface, so this needs to be restricted. That is, when the rolling degree per rolling pass exceeds 24%, the unevenness on the surface of the rolling roll is easily transferred to the surface of the material. Therefore, it is necessary to control this to 24% or less. The degree of rolling work per rolling pass is more preferably 20% or less. However, if the degree of working is too low, the number of rolling passes until finishing to a desired thickness increases, and the productivity deteriorates. The degree of processing per rolling pass is set to 5% or more.

  The copper foil of the present invention was subjected to 180 ° adhesive bending with the polyimide film surface on the inside of a sample of a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less in which a copper foil and a polyimide film having a film thickness of 25 μm were laminated. When performed, the number of times of bending until the copper foil breaks is preferably 3 times or more, and more preferably 5 times or more. If the flexibility is good so as to satisfy such conditions, it can be suitably used as an LCD module FPC.

(Roughening treatment and surface treatment copper foil production method)
The rolled copper foil used in the present invention is applied to the surface of the copper foil after degreasing for the purpose of improving the peeling strength of the copper foil after lamination on the roughened surface that becomes the adhesive surface with the resin substrate. A surface-treated copper foil can be obtained by performing a roughening treatment for performing knurled electrodeposition. This roughening treatment can be performed by copper-cobalt-nickel alloy plating, and further by subjecting the surface of the roughening treatment to rust prevention treatment.

Copper as roughening treatment - cobalt - nickel alloy plating, by electrolytic plating, for example, the adhesion amount is in the nickel-cobalt -100~1500μg / dm ² of copper -100~3000μg / dm ² of 15~40mg / dm ² Such a ternary alloy layer can be formed.

An example of plating conditions for forming such ternary copper-cobalt-nickel alloy plating is as follows.
Plating bath composition Cu: 10 to 20 g / L, Co: 1 to 10 g / L, Ni: 1 to 10 g / L
pH: 1-4
Bath temperature: 30-50 ° C
Current density: 20-30 A / dm ²
Plating time: 1-5 seconds

After roughening treatment, such as cobalt by adhesion amount 200~3000μg of / dm ² of cobalt and 100~1300μg / dm ² of nickel on the roughened surface - it is possible to form a nickel alloy plating layer. This treatment can be regarded as a kind of rust prevention treatment in a broad sense. This cobalt-nickel alloy plating layer needs to be performed to such an extent that the adhesive strength between the copper foil and the substrate is not substantially reduced.

An example of plating conditions for forming the cobalt-nickel alloy plating after the roughening treatment is as follows.
Plating bath composition Co: 1-20 g / L, Ni: 1-20 g / L
pH: 1.5-3.5
Bath temperature: 30-80 ° C
Current density: 1 to 20 A / dm ²
Plating time: 0.5-4 seconds

  A zinc plating layer or zinc-nickel alloy plating layer may be further formed on the above cobalt-nickel alloy plating, and a rust prevention layer is formed on the outermost surface by chromate treatment or application of a silane coupling agent. You may do it.

(Specular reflectance)
As described above, the surface of the resin layer after removing the copper layer of the FPC is a replica to which the irregularities on the surface of the copper foil are transferred. Therefore, the surface form after the roughening treatment directly affects the surface of the resin layer. However, the distribution and form of the roughened particles formed by the roughening process are affected by the copper foil surface form before the roughening process. As a result of conducting an investigation focusing on this point, the reason is not clear, but the average value of the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling is 30. In the above case, it was found that by performing an appropriate roughening treatment on the copper foil, a copper foil having a good visibility with an Sv value of 3.5 or more described later can be obtained. In addition, when the average value of the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling is less than 30, the Sv value is less than 3.5. Visibility is insufficient. Therefore, in order to ensure good visibility, the average of the specular reflectance at the incident angle of 20 ° in the rolling parallel direction and the specular reflectance at the incident angle of 20 ° in the rolling perpendicular direction is applied to the copper foil before the roughening treatment. The value needs to be 30 or more, preferably 35 or more.

(Sv value)
The value of “Sv” is obtained as follows. First, after bonding the copper foil to both sides of the polyimide base resin, the copper foil on both sides was removed by etching, and the printed matter on which the line-shaped mark was printed was laid under the exposed polyimide substrate, and the printed matter was Take a picture with a CCD camera through a polyimide substrate. For an image obtained by photographing, the brightness at each observation point is measured along a direction perpendicular to the direction in which the observed line-shaped mark extends, and an observation point-lightness graph is created. In this graph, the difference between the top average value Bt and the bottom average value Bb of the brightness curve generated from the end of the mark to the portion where the mark is not drawn is the gradation difference of brightness, and this is expressed as ΔB (= Bt−Bb). ), The gradation of brightness is set so that ΔB is 40 or more. In addition, in the depth range from the intersection of the lightness curve and Bt to 0.1 ΔB on the basis of Bt, the value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and Bt is The value of Sv is defined by the following equation (1), where t2 is the value indicating the position of the intersection closest to the line mark among the intersections of the lightness curve and 0.1 ΔB.
Sv = (ΔB × 0.1) / (t1-t2) (1)
In the observation point-lightness graph, the horizontal axis represents position information (pixel × 0.1), and the vertical axis represents the value of brightness (gradation).
Here, “top average value Bt of the lightness curve”, “bottom average value Bb of the lightness curve”, and “t1”, “t2”, and “Sv” described later will be described with reference to the drawings.
FIGS. 1A and 1B are schematic views for defining Bt and Bb when the mark width is about 0.3 mm. When the mark width is about 0.3 mm, a V-shaped brightness curve may be obtained as shown in FIG. 1A, or a brightness curve having a bottom as shown in FIG. 1B. . In any case, the “top average value Bt of the lightness curve” indicates the average value of lightness when measured at 5 locations (a total of 10 locations on both sides) at 30 μm intervals from the positions 50 μm away from the end positions on both sides of the mark. . On the other hand, the “bottom average value Bb of the lightness curve” indicates the minimum value of lightness at the tip of the V-shaped valley when the lightness curve is V-shaped as shown in FIG. When it has the bottom of (b), the value of the center part of about 0.3 mm is shown.
FIG. 2 is a schematic diagram that defines t1, t2, and Sv. “T1 (pixel × 0.1)” is a value indicating an intersection point closest to the line-shaped mark among intersection points of the lightness curve and Bt and a position of the intersection point (value on the horizontal axis of the observation point-lightness graph) ). “T2 (pixel × 0.1)” is the line-shaped mark among the intersections of the lightness curve and 0.1ΔB in the depth range from the intersection of the lightness curve and Bt to 0.1ΔB with reference to Bt. And the value (the value on the horizontal axis of the observation point-brightness graph) indicating the position of the intersection closest to. At this time, regarding the slope of the brightness curve indicated by the line connecting t1 and t2, Sv (gradation / pixel × 0.1) calculated by 0.1 ΔB in the y-axis direction and (t1−t2) in the x-axis direction. ). One pixel on the horizontal axis corresponds to a length of 10 μm. Further, Sv is measured on both sides of the mark, and a small value is adopted. Further, when the shape of the lightness curve is unstable and there are a plurality of the “intersections between the lightness curve and Bt”, the intersection closest to the mark is adopted.
In the image taken by the CCD camera, the brightness is high at the portion where the mark is not attached, but the brightness decreases as soon as the end of the mark is reached. If the visibility of the polyimide substrate is good, such a lowered state of brightness is clearly observed. On the other hand, if the visibility of the polyimide substrate is poor, the lightness does not suddenly drop from “high” to “low” in the vicinity of the mark end, but the state of decline is slow and the state of lightness decline is unclear. End up.
For this reason, with respect to the polyimide substrate from which the surface-treated copper foil of the present invention has been bonded and removed, the printed matter with the mark placed underneath, the observation point obtained from the image of the mark portion taken with a CCD camera over the polyimide substrate -It is preferable to control the slope of the brightness curve near the edge of the mark drawn in the brightness graph. More specifically, the difference between the top average value Bt and the bottom average value Bb of the lightness curve is ΔB (ΔB = Bt−Bb), and the line of the intersections of the lightness curve and Bt in the observation point-lightness graph. In the depth range from the intersection of the lightness curve and Bt to 0.1 ΔB with reference to Bt, the value indicating the position of the intersection closest to the shape mark (the value on the horizontal axis of the observation point-lightness graph) is t1. When the value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and 0.1ΔB (the observation point—the value on the horizontal axis of the lightness graph) is t2, the above equation (1) It is preferable that Sv defined by is 3.5 or more. According to such a configuration, the discrimination power of the mark over the polyimide by the CCD camera is improved without being affected by the type and thickness of the substrate resin. For this reason, it is possible to produce a polyimide substrate with excellent visibility, and the positioning accuracy by marking when performing a predetermined treatment on the polyimide substrate in an electronic substrate manufacturing process or the like is improved, thereby improving the yield. can get. Sv is preferably 3.9 or more, more preferably 5.0 or more. The upper limit of Sv is not particularly limited, but is, for example, 70 or less, 30 or less, 15 or less, and 10 or less. According to such a configuration, the boundary between the mark and the non-mark portion becomes clearer, the positioning accuracy is improved, the error due to the mark image recognition is reduced, and the alignment can be performed more accurately.

The rolled copper foil or surface-treated copper foil of the present invention can be bonded to a resin substrate from the roughened surface side to produce a laminate. The resin substrate is not particularly limited as long as it has characteristics applicable to a printed wiring board and the like. For example, a polyester film such as polyethylene terephthalate (PET), a polyimide film, a liquid crystal polymer (LCP) film, etc. are used. can do.
In addition, the method of laminating can be laminated and bonded to a rolled copper foil under high temperature and high pressure without using an adhesive to a base material such as a polyimide film, or a polyimide precursor is applied. -A laminated board can be manufactured by drying and hardening.

  EXAMPLES Examples of the present invention will be described below, but these are provided for better understanding of the present invention and are not intended to limit the present invention.

[Manufacture of rolled copper foil]
Oxygen-free copper (OFC, JIS H3100 C1020) or tough pitch copper (TPC, JIS H3100 C1100) is dissolved, and Ag and / or Sn and / or Zr are added in the amounts shown in Tables 1 and 2 as necessary. A 30 mm, 60 mm wide, 120 mm long ingot was cast and rolled to 10 mm by hot rolling. Thereafter, annealing and rolling were repeated, and in the final cold rolling, a work roll finished with a surface roughness Ra of 0.01 to 0.1 μm was used, and in the final cold rolling under the conditions shown in Tables 1 and 2. The maximum rolling work degree of 1 pass of rolling was adjusted, and it rolled to thickness 6-35 micrometers.

[Roughening of copper foil]
About each copper foil, the plating process was performed on the surface bonded with resin on the following conditions as a roughening process.
-Plating bath composition Cu: 15 g / L, Co: 8.5 g / L, Ni: 8.6 g / L
-Treatment solution pH: 2.5
・ Processing temperature: 38 ℃
・ Current density: 20 A / dm ²
・ Plating time: 2.0 seconds

Various evaluations were performed as follows for the samples prepared as described above.
(1) Specular reflectivity The specular reflectivity in the rolling parallel direction and the specular reflectivity in the direction perpendicular to the rolling were measured for the copper foil before the roughening treatment. VG-1D manufactured by Nippon Denshoku Industries Co., Ltd. was used as the measuring device, and the sample was cut into a 25 mm square size, and the mirror surface in the rolling parallel direction per sample at an incident angle of 20 ° by the method specified in JIS Z 8741. The reflectance and the specular reflectance in the direction perpendicular to the rolling were each measured three times, and the average of a total of six measurements was taken as the specular reflectance.

(2) Bendability A sample of a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less obtained by laminating each copper foil and a polyimide film having a film thickness of 25 μm was prepared, and 180 ° contact bending was performed with the polyimide film surface being the inside. Sometimes, the number of bendings until the copper foil broke was measured.

(3) Peel strength In accordance with PC-TM-650, the normal peel strength was measured with a tensile tester Autograph 100, and it can be used as a laminated substrate when the peel strength is 0.7 N / mm or more. "

(4) Visibility (Sv value)
The copper foil after the roughening treatment was bonded to both surfaces of a polyimide film (Kaneka thickness 50 μm), and the copper foil was dissolved and removed with an aqueous ferric chloride solution to prepare a sample film. Next, a printed material on which a line-shaped black mark is printed is laid under the sample film, the printed material is photographed with a CCD camera through the sample film, and the observed line-shaped mark extends in the image obtained by photographing. The brightness at each observation point was measured along the direction perpendicular to the direction. In the observation point-lightness graph thus measured, the slope (angle) of the lightness curve generated from the end of the mark to the portion where no mark was drawn was measured. FIG. 3 is a schematic diagram showing the configuration of the measuring apparatus used at this time and the method of measuring the slope of the brightness curve. Further, ΔB, t1, t2, and Sv were measured by the following photographing apparatus as shown in FIG. One pixel on the horizontal axis corresponds to a length of 10 μm. As another method for obtaining Sv which is the slope of the lightness curve, the ratio of the length of one pixel to one gradation in the lightness curve graph is 3.5: 5 (the length of one pixel in the lightness curve graph). : The value of t1, t2, and Sv can also be calculated in the graph of the lightness curve where the length of one gradation in the graph of the lightness curve = 3.5 (mm): 5 (mm)).
The photographing device has a CCD camera, a stage (white) on which a polyimide substrate is placed with a marked paper underneath, an illumination power source that irradiates light onto the photographing portion of the polyimide substrate, and a paper with a mark to be photographed. It has a transfer machine for transferring the polyimide substrate for evaluation placed on the stage onto the stage. The main specifications of the set of imaging devices used for the measurement are shown below.
・ Photographing device: Sheet inspection device Mujken manufactured by Nireco Corporation
CCD camera: 8192 pixels (160 MHz), 1024 gradation digital (10 bits)
・ Power supply for lighting: High frequency lighting power supply ・ Lighting: Fluorescent lamp (30W)
For the lightness shown in FIG. 3, 0 means “black”, lightness 255 means “white”, and the gray level from “black” to “white” (black and white shading, gray scale) Is divided into 256 gradations for display.
Tables 1 and 2 show the conditions and evaluation of the above tests.

(Evaluation results)
In Examples 1 to 16, the average value of the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the rolling perpendicular direction is 30 or more, and bendability, peel strength, and The visibility of the resin was good.
In Comparative Examples 1 to 6, the average value of the specular reflectivity at an incident angle of 20 ° in the rolling parallel direction and the specular reflectivity at an incident angle of 20 ° in the rolling perpendicular direction is less than 30, and the resin visibility is poor. Met. Some also had poor bendability.
In Comparative Example 7, since the surface roughness Ra of the rolled work roll in the final cold rolling exceeds the specified value of 0.08 μm, the specular reflectance at the incident angle of 20 ° in the rolling parallel direction and the incident in the direction perpendicular to the rolling direction. The average value with the specular reflectance at an angle of 20 ° was less than 30, and the visibility of the resin was poor.
In Comparative Example 8, since the maximum rolling degree of rolling in one pass in the final cold rolling exceeds the specified value of 24%, the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the incident angle in the perpendicular direction of rolling. The average value with the specular reflectance of 20 ° was less than 30, and the visibility of the resin was poor.

Claims (10)

  Tough pitch copper standardized to JIS H3100 C1100 or oxygen-free copper standardized to JIS H3100 C1020, the average of the specular reflectance at an incident angle of 20 ° in the rolling parallel direction and the specular reflectance at an incident angle of 20 ° in the direction perpendicular to the rolling A rolled copper foil having a value of 30 or more.   A copper foil containing 0.002 to 0.05 mass% of Ag in addition to tough pitch copper specified in JIS H3100 C1100, and having a mirror reflectivity with an incident angle of 20 ° in the rolling parallel direction and an incident angle of 20 in the direction perpendicular to the rolling direction. A rolled copper foil having an average value of 30 or more with a specular reflectance of °.   A copper foil containing 0.002 to 0.05 mass% in total of one or more of Ag, Sn and Zr in oxygen-free copper specified in JIS H3100 C1020, and having an incident angle of 20 ° in the rolling parallel direction The rolled copper foil whose average value of the specular reflectivity of this and the specular reflectivity of 20 degrees of incident angles of a perpendicular direction of rolling is 30 or more.   The rolled copper foil according to any one of claims 1 to 3, wherein the thickness is 6 to 35 µm.   When a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less obtained by laminating the copper foil and a polyimide film having a film thickness of 25 μm was subjected to 180 ° adhesion bending with the polyimide film surface inside, the copper The rolled copper foil according to any one of claims 1 to 4, wherein the number of bending times until the foil breaks is 3 or more.   The rolled copper foil according to claim 5, wherein the number of times of bending until the copper foil breaks is 5 or more. It is the surface treatment copper foil in which the roughening particle was formed by the roughening process on the surface of at least one of the rolled copper foil in any one of Claims 1-6, Comprising: The said copper foil is both surfaces of a polyimide resin board | substrate. After bonding, the copper foil on both sides is removed by etching,
When the printed matter on which a line-shaped mark is printed is laid under the exposed polyimide substrate, and the printed matter is photographed with a CCD camera through the polyimide substrate,
For the image obtained by the photographing, the observation point-brightness graph produced by measuring the brightness for each observation point along the direction perpendicular to the direction in which the observed line-shaped mark extends,
The difference ΔB (ΔB = Bt−Bb) between the top average value Bt and the bottom average value Bb of the brightness curve generated from the end of the mark to the part where the mark is not drawn is 40 or more, and the observation point-lightness graph , The value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and Bt is t1, and the depth range from the intersection of the lightness curve and Bt to 0.1 ΔB with reference to Bt , When the value indicating the position of the intersection closest to the line-shaped mark among the intersections of the lightness curve and 0.1 ΔB is t2, Sv defined by the following equation (1) is 3.5 or more Surface-treated copper foil.
Sv = (ΔB × 0.1) / (t1-t2) (1)   The surface-treated copper foil of Claim 7 from which Sv defined by (1) Formula in the said brightness curve will be 5.0 or more.   The laminated board comprised by laminating | stacking the rolled copper foil and resin substrate in any one of Claims 1-6.   The laminated board comprised by laminating | stacking the surface-treated copper foil and resin substrate of Claim 7 or 8.