WO2022255421A1

WO2022255421A1 - Roughened copper foil, copper clad laminate, and printed wiring board

Info

Publication number: WO2022255421A1
Application number: PCT/JP2022/022387
Authority: WO
Inventors: 翼加藤; 歩立岡; 博鈞楊; 彰太川口
Original assignee: 三井金属鉱業株式会社
Priority date: 2021-06-03
Filing date: 2022-06-01
Publication date: 2022-12-08
Also published as: TWI808775B; JPWO2022255421A1; TW202248458A; KR20240017841A

Abstract

Provided is a roughened copper foil having excellent transmission characteristics and circuit linearity and capable of achieving high peel strength when used in a copper clad laminate or a printed wiring board. This roughened copper foil has a roughened surface on at least one side. The roughened surface has a value Rdc/Rku, which is the ratio of the cut level difference Rdc of the roughness curve to the kurtosis Rku of the roughness curve, of 0.180 μm or less, and has a value of the maximum cross-sectional height Wt of the undulation curve of 2.50 μm or more and 10.00 μm or less. Rku and Wt are values measured in accordance with JIS B0601-2013, and Rdc is a value obtained as the difference in cut level c in the height direction between a load length ratio of 20% and a load length ratio of 80% in accordance with JIS B0601-2013.

Description

Roughened copper foil, copper clad laminate and printed wiring board

The present invention relates to roughened copper foils, copper clad laminates and printed wiring boards.

In the manufacturing process of printed wiring boards, copper foil is widely used in the form of copper-clad laminates laminated with insulating resin substrates. In this regard, it is desired that the copper foil and the insulating resin base material have high adhesive strength in order to prevent the wiring from being peeled off during the production of the printed wiring board. Therefore, in ordinary copper foils for manufacturing printed wiring boards, the bonding surface of the copper foil is roughened to form unevenness made of fine copper particles, and the unevenness is pressed into the insulating resin base material. Adhesion is improved by exerting an anchor effect.

As a copper foil that has undergone such a roughening treatment, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-172785) has a copper foil and a roughening treatment layer on at least one surface of the copper foil, A surface-treated copper foil having an arithmetic mean roughness Ra of 0.08 μm or more and 0.20 μm or less on the roughened layer side surface and a TD (width direction) gloss of the roughened layer side surface of 70% or less. disclosed. According to such a surface-treated copper foil, it is said that detachment of roughening particles provided on the surface of the copper foil is well suppressed, and the occurrence of wrinkles and streaks during lamination with an insulating substrate is well suppressed. there is

By the way, in recent years, as the functions of portable electronic devices have become more sophisticated, the frequency of signals, whether digital or analog, has been increasing in order to process large amounts of data at high speed. It has been demanded. For such high-frequency printed wiring boards, reduction in transmission loss is desired in order to enable transmission of high-frequency signals without deterioration. A printed wiring board comprises a copper foil processed into a wiring pattern and an insulating base material. losses.

In this regard, a roughened copper foil has been proposed to reduce transmission loss. For example, Patent Document 2 (Japanese Patent Application Laid-Open No. 2015-148011) describes a technique for providing a surface-treated copper foil with low signal transmission loss and a laminated board using the same, and the copper foil surface is improved by surface treatment. It discloses that the skewness Rsk based on JIS B0601-2001 is controlled within a predetermined range of -0.35 or more and 0.53 or less.

JP 2018-172785 A JP 2015-148011 A

As mentioned above, in recent years, there has been a demand to improve the transmission characteristics (high frequency characteristics) of printed wiring boards. In order to meet these demands, attempts have been made to finely roughen the bonding surface of the copper foil with the insulating resin substrate. That is, in order to reduce the unevenness of the copper foil surface, which is a factor that increases the transmission loss, the surface of the copper foil with small undulations (for example, the surface of the double-sided smooth foil and the electrode surface of the electrolytic copper foil) is subjected to a fine roughening treatment. can be considered. In addition, it is conceivable that the linearity of the wiring pattern (hereinafter referred to as circuit linearity) at the time of circuit formation is improved by using a roughened copper foil with small undulations. However, when a copper-clad laminate is processed or a printed wiring board is manufactured using such a roughened copper foil, the peel strength between the copper foil and the substrate is generally low, resulting in poor adhesion reliability. can occur.

The present inventors have recently found that the Rdc/Rku, which is the ratio of the cutting level difference Rdc to the kurtosis Rku, and the maximum cross-sectional height Wt on the surface of the roughened copper foil are controlled within a predetermined range. It has been found that a copper-clad laminate or printed wiring board produced by using the compound is excellent in transmission characteristics and circuit linearity, and can achieve high peel strength.

Accordingly, an object of the present invention is to provide a roughened copper foil that is excellent in transmission characteristics and circuit linearity and capable of achieving high peel strength when used in copper-clad laminates or printed wiring boards. be.

According to the present invention, the following aspects are provided.
[Aspect 1]
A roughened copper foil having a roughened surface on at least one side,
In the roughened surface, Rdc/Rku, which is the ratio of the cutting level difference Rdc of the roughness curve to the kurtosis Rku of the roughness curve, is 0.180 μm or less, and the maximum cross-sectional height Wt of the undulation curve is 2.0 μm. 50 μm or more and 10.00 μm or less,
The Rku is a value measured in accordance with JIS B0601-2013 under the conditions of a magnification of 200, a cutoff wavelength of 0.3 μm with a cutoff value λs, and a cutoff wavelength of 5 μm with a cutoff value λc,
The Rdc is measured in accordance with JIS B0601-2013 under the conditions of a magnification of 200, a cutoff wavelength of 0.3 μm with a cutoff value λs, and a cutoff wavelength of 5 μm with a cutoff value λc. is the value obtained as the difference (c(Rmr1)-c(Rmr2)) in the cutting level c in the height direction between the load length ratio (Rmr1) of 20% and the load length ratio (Rmr2) of 80%;
The Wt is a value measured in accordance with JIS B0601-2013 under the conditions of a magnification of 20 times, a cutoff wavelength of 5 μm with a cutoff value λc, and no cutoff with a cutoff value λf. Copper foil.
[Aspect 2]
The roughened copper foil according to aspect 1, wherein the roughened surface has a maximum cross-sectional height Wt of 2.90 μm or more and 10.00 μm or less.
[Aspect 3]
The roughened copper foil according to aspect 1 or 2, wherein the roughened surface has a cutting level difference Rdc of 0.45 μm or less.
[Aspect 4]
The roughened surface has a maximum peak height Wp of an undulating curve of 1.00 μm or more and 6.00 μm or less, and the Wp is cut off by a cutoff value λc at a magnification of 20 times in accordance with JIS B0601-2013. The roughened copper foil according to any one of aspects 1 to 3, which is a value measured under conditions in which a wavelength of 5 μm and cutoff with a cutoff value λf are not performed.
[Aspect 5]
The roughened surface has an average height Rc of roughness curve elements of 0.70 μm or less, and the Rc is a cutoff wavelength of 0 at a magnification of 200 and a cutoff value λs in accordance with JIS B0601-2013. .3 μm and a cutoff wavelength of 5 μm with a cutoff value λc.
[Aspect 6]
The roughened surface has a cutting level difference Wdc of the undulating curve of 1.20 μm or more and 3.10 μm or less, and the Wdc is cut off by a cutoff value λc at a magnification of 20 times in accordance with JIS B0601-2013. Height direction between load length ratio (Wmr1) 20% and load length ratio (Wmr2) 80% in the undulation curve measured under the condition that the wavelength is 5 μm and the cutoff value λf is not cut off. The roughened copper foil according to any one of aspects 1 to 5, which is a value obtained as a difference in cutting level c (c(Wmr1)-c(Wmr2)).
[Aspect 7]
The roughened surface has a roughness curve root-mean-square height Rq of 0.290 μm or less, and the Rq is a cutoff wavelength with a cutoff value λs at a magnification of 200 in accordance with JIS B0601-2013. 7. The roughened copper foil according to any one of aspects 1 to 6, which is a value measured under the conditions of 0.3 μm and a cutoff wavelength of 5 μm with a cutoff value λc.
[Aspect 8]
The roughened copper foil according to any one of modes 1 to 7, wherein the roughened surface has a kurtosis Rku of 1.30 or more and 8.00 or less.
[Aspect 9]
The roughened copper foil according to any one of aspects 1 to 8, wherein the roughened surface is provided with an anticorrosive layer and/or a silane coupling agent-treated layer.
[Aspect 10]
The roughened copper foil according to any one of aspects 1 to 9, wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the deposition surface side of the electrolytic copper foil.
[Aspect 11]
A copper clad laminate comprising the roughened copper foil according to any one of aspects 1 to 10.
[Aspect 12]
A printed wiring board comprising the roughened copper foil according to any one of aspects 1 to 10.

FIG. 4 is a diagram for explaining a load curve of a roughness curve determined according to JIS B0601-2013; FIG. 4 is a diagram for explaining a load length ratio Rmr(c) determined according to JIS B0601-2013; FIG. 4 is a diagram for explaining a cutting level difference Rdc determined in compliance with JIS B0601-2013; FIG. 4 is a diagram for explaining that the surface unevenness of the roughening-treated copper foil is composed of roughening particle components and waviness components. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the roughening process copper foil of this invention.

DEFINITIONS Definitions of terms or parameters used to define the present invention are provided below.

In this specification, the "load curve of the roughness curve" refers to the substantial part that appears when the roughness curve is cut at cutting level c, determined in accordance with JIS B0601-2013, as shown in FIG. is a curve representing the ratio of as a function of c. That is, the load curve of the roughness curve can also be said to be a curve representing the height at which the load length ratio Rmr(c) is from 0% to 100%. The load length ratio Rmr(c) is the ratio of the load length of the roughness curve element at the cutting level c to the evaluation length, determined in accordance with JIS B0601-2013, as shown in FIG. is a parameter that represents

As used herein, "cutting level difference Rdc of roughness curve", "cutting level difference Rdc" or "Rdc" refers to roughness measured in accordance with JIS B0601-2013, as shown in FIG. A parameter that represents the difference (c(Rmr1)-c(Rmr2)) in the cutting level c in the height direction between the two load length ratios Rmr1 and Rmr2 (where Rmr1<Rmr2) in the load curve of the curve. . Assume herein that Rdc is calculated by specifying Rmr1 as 20% and Rmr2 as 80%.

As used herein, "roughness curve root mean square height Rq", "root mean square height Rq" or "Rq" means that the reference length measured in accordance with JIS B0601-2013 is Z (x) is a parameter representing the root mean square of (Z(x) represents the height of the roughness curve at an arbitrary position x).

As used herein, the terms "roughness curve kurtosis Rku", "kurtosis Rku" or "Rku" are dimensionless by the square root mean square height Rq measured in accordance with JIS B0601-2013. It is a parameter representing the mean square of Z(x) in the reference length. Rku means kurtosis, which is a measure of the sharpness of the surface, and represents the sharpness of the height distribution. Rku=3 means that the height distribution is a normal distribution, Rku>3 means that the height distribution is sharp, and Rku<3 means that the height distribution is flat. do.

As used herein, "Rdc/Rku" is a parameter representing the ratio of the cleavage level difference Rdc to the kurtosis Rku.

As used herein, "average height Rc of the roughness curve element", "average height Rc" or "Rc" refers to the roughness curve element at the reference length measured in accordance with JIS B0601-2013. This parameter represents the average height. Roughness curve element means a set of adjacent peaks and valleys in the roughness curve. A minimum height and a minimum length are specified for the peaks or valleys that constitute the roughness curve element, and the height is 10% or less of the maximum height Rz, or the length is 1% or less of the reference length. Some are considered noise and are part of the valleys or mountains that follow.

In this specification, "maximum cross-sectional height Wt of undulation curve", "maximum cross-sectional height Wt" or "Wt" refers to the crest height of the undulation curve at the evaluation length measured in accordance with JIS B0601-2013. This parameter represents the sum of the maximum depth and the maximum valley depth.

As used herein, "maximum peak height Wp of the undulation curve", "maximum peak height Wp" or "Wp" refers to the peak height of the undulation curve at the reference length measured in accordance with JIS B0601-2013. This parameter represents the maximum value.

In this specification, the "load curve of the undulation curve" is a curve that expresses the ratio of the substantial part that appears when the undulation curve is cut at the cutting level c as a function of c, which is determined in accordance with JIS B0601-2013. is. That is, the load curve of the undulation curve can also be said to be a curve representing the height at which the load length ratio Wmr(c) is from 0% to 100%. The load length ratio Wmr(c) is a parameter representing the ratio of the load length of the undulating curve element at the cut level c to the evaluation length determined in accordance with JIS B0601-2013.

As used herein, the terms "cutting level difference Wdc of waviness curve", "cutting level difference Wdc", or "Wdc" refer to two load lengths in a waviness curve load curve measured in accordance with JIS B0601-2013. This is a parameter representing the difference (c(Wmr1)-c(Wmr2)) in the cutting level c in the height direction between the depth ratios Wmr1 and Wmr2 (where Wmr1<Wmr2). Assume herein that Wdc is calculated by specifying Wmr1 as 20% and Wmr2 as 80%.

Rdc, Rq, Rku, Rc, Wt, Wp and Wdc can be calculated by measuring a surface profile of a predetermined measurement length on the roughened surface with a commercially available laser microscope. In this specification, the roughness parameters Rdc, Rq, Rku, and Rc are measured under the conditions of a magnification of 200, a cutoff wavelength of 0.3 μm with a cutoff value λs, and a cutoff wavelength of 5 μm with a cutoff value λc. shall be Also, the reference length and the evaluation length used for calculating the roughness parameter are set to 5 μm and 25 μm, respectively. On the other hand, the waviness parameters Wt, Wp, and Wdc are measured under the conditions of a magnification of 20, a cutoff wavelength of 5 μm with a cutoff value λc, and no cutoff with a cutoff value λf. Also, the reference length and the evaluation length used to calculate the waviness parameter are both the same as the measured length of the roughened surface. In the examples described later, the waviness parameter is measured for a region of 643.973 μm long×643.393 μm wide on the roughened surface. 643.973 μm in case and 643.393 μm in lateral direction. When both the objective lens and the optical zoom are used in the measurement with the laser microscope, the above magnification corresponds to the value obtained by multiplying the magnification of the objective lens by the magnification of the optical zoom. For example, when the objective lens magnification is 100 times and the optical zoom magnification is 2 times, the magnification is 200 times (=100×2). In addition, preferable measurement conditions and analysis conditions for the surface profile by the laser microscope will be shown in Examples below.

In this specification, the "electrode surface" of the electrolytic copper foil refers to the surface that was in contact with the cathode when the electrolytic copper foil was manufactured.

In this specification, the "deposition surface" of the electrolytic copper foil refers to the surface on which electrolytic copper is deposited during the production of the electrolytic copper foil, that is, the surface that is not in contact with the cathode.

Roughened Copper Foil The copper foil of the present invention is a roughened copper foil. This roughened copper foil has a roughened surface on at least one side. In this roughened surface, Rdc/Rku, which is the ratio of the cutting level difference Rdc of the roughness curve to the kurtosis Rku of the roughness curve, is 0.180 μm or less. Further, the roughened surface has a maximum cross-sectional height Wt of an undulating curve of 2.50 μm or more and 10.00 μm or less. By controlling Rdc/Rku and the maximum cross-sectional height Wt on the surface of the roughened copper foil within a predetermined range in this way, a copper clad laminate or a printed wiring board manufactured using the roughened copper foil can achieve transmission It is excellent in characteristics (high frequency characteristics) and circuit linearity, and can achieve high peel strength.

It is inherently difficult to achieve both excellent transmission characteristics and high peel strength, as well as excellent circuit linearity and high peel strength. In order to improve transmission characteristics or circuit linearity, it is necessary to reduce the unevenness of the copper foil surface. This is because they are in a trade-off relationship. Here, as shown in FIG. 4, the unevenness on the roughened copper foil surface consists of a "roughening particle component" and a "waviness component" having a longer period than the roughening particle component. In general, in order to improve transmission characteristics or circuit linearity, a copper foil surface with small undulations (for example, the surface of a double-sided smooth foil or the electrode surface of an electrolytic copper foil) is subjected to a fine roughening treatment to reduce the roughness. However, when a copper-clad laminate or a printed wiring board is produced using such a roughened copper foil, the peel strength between the copper foil and the substrate is generally low.

In response to this problem, the present inventors studied the effects of roughened particles and undulations on the copper foil surface on transmission characteristics, circuit linearity, and peel strength. As a result, it was found that, contrary to expectations, the waviness component of the copper foil had little effect on the transmission characteristics, and that the size of the roughening particles mainly affected the transmission characteristics. Then, the present inventors made the bumps (roughened particles) finer in order to improve the transmission characteristics, and compensated for the insufficient adhesion by undulating the copper foil, which has a small effect on the transmission characteristics. , it was found that both excellent transmission characteristics and adhesion reliability due to high peel strength can be achieved. It was also found that by controlling the waviness of the copper foil within a predetermined range, excellent circuit linearity and high peel strength can be achieved in a well-balanced manner. Specifically, it was found that by using Rdc/Rku obtained by dividing the cutting level difference Rdc by the kurtosis Rku, it was possible to accurately reflect the shape of minute bumps (roughening particles) that affect the transmission characteristics. It has been found that excellent transmission characteristics can be achieved by controlling Rku to 0.180 μm or less. Furthermore, we have found that the maximum cross-sectional height Wt can accurately reflect the undulation component on a wide range of roughened surfaces, and by setting this Wt to 2.50 μm or more and 10.00 μm or less, the circuit linearity is excellent. We also found that high peel strength between the copper foil and the substrate can be achieved by utilizing the waviness of the copper foil.

Roughened particle components and waviness components on the copper foil surface that affect transmission characteristics, circuit linearity, or peel strength can be distinguished by properly using the measurement magnification in a laser microscope and the cutoff values λs, λc, and λf. . Specifically, by measuring the roughened surface at a high magnification of 200 times, it is possible to accurately evaluate the fine irregularities of the roughened surface that affect the transmission characteristics. Then, by using a roughness curve obtained by measuring the roughened surface under the conditions of a cutoff wavelength of 0.3 μm with a cutoff value λs and a cutoff wavelength of 5 μm with a cutoff value λc, the influence of the waviness component can be reduced. A cut roughness parameter can be calculated. Therefore, it can be said that the roughness parameters in the present invention, that is, Rdc, Rku, Rdc/Rku, Rc and Rq are parameters that accurately reflect the roughened particle component on the copper foil surface. can be evaluated accurately. On the other hand, by measuring the roughened surface at a low magnification of 20 times, it is possible to extensively evaluate the height (undulation) of the entire roughened surface that affects circuit linearity and adhesion reliability. can. Then, by using the undulation curve obtained by measuring the roughened surface under the conditions where the cutoff wavelength is 5 μm with the cutoff value λc and the cutoff value λf is not performed, the effect of the roughened particle component is cut. undulation parameters can be calculated. Therefore, it can be said that the waviness parameters in the present invention, that is, Wt, Wp and Wdc, are parameters that adequately reflect waviness components on the copper foil surface, and by using these indices, circuit linearity and peel strength can be accurately evaluated. can do.

The roughened surface of the roughened copper foil has a maximum cross-sectional height Wt of the undulating curve of 2.50 μm or more and 10.00 μm or less, preferably 2.90 μm or more and 10.00 μm or less, more preferably 3.10 μm or more. It is 9.00 μm or less, more preferably 3.30 μm or more and 7.00 μm or less. When the Wt is within the above range, excellent circuit linearity and high peel strength can be achieved in a well-balanced manner while ensuring excellent transmission characteristics.

Rdc/Rku of the roughened surface of the roughened copper foil is 0.180 μm or less, preferably 0.015 μm or more and 0.150 μm or less, more preferably 0.030 μm or more and 0.110 μm or less, and still more preferably 0 0.045 μm or more and 0.080 μm or less. When Rdc/Rku is within the above range, excellent transmission characteristics can be achieved while maintaining excellent circuit linearity and high peel strength.

The roughened surface of the roughened copper foil preferably has a roughness curve cutting level difference Rdc of 0.45 μm or less, more preferably 0.04 μm or more and 0.40 μm or less, and still more preferably 0.08 μm or more. It is 0.35 μm or less, particularly preferably 0.12 μm or more and 0.30 μm or less. When Rdc is within the above range, it becomes easier to control Rdc/Rku within the above range, and further excellent transmission characteristics can be achieved.

The roughened surface of the roughened copper foil preferably has a roughness curve kurtosis Rku of 1.30 or more and 8.00 or less, more preferably 1.50 or more and 5.50 or less, and still more preferably 2.50 or more. 00 or more and 4.50 or less, particularly preferably 2.50 or more and 3.20 or less. When Rku is within the above range, it becomes easier to control Rdc/Rku within the above range, and further excellent transmission characteristics can be achieved.

The roughened surface of the roughened copper foil preferably has a peak height Wp of 1.00 μm or more and 6.00 μm or less, more preferably 1.20 μm or more and 5.00 μm or less, and still more preferably 1 .30 μm or more and 4.30 μm or less, particularly preferably 1.40 μm or more and 3.70 μm or less. When Wp is within the above range, excellent circuit linearity and high peel strength can be achieved in a better balance while ensuring excellent transmission characteristics.

The roughened surface of the roughened copper foil preferably has an average height Rc of roughness curve elements of 0.70 μm or less, more preferably 0.06 μm or more and 0.60 μm or less, and still more preferably 0.12 μm. 0.50 μm or less, particularly preferably 0.18 μm or more and 0.50 μm or less. When Rc is within the above range, even better transmission characteristics can be achieved while maintaining excellent circuit linearity and high peel strength.

The roughened surface of the roughened copper foil preferably has a cutting level difference Wdc of the undulating curve of 1.20 μm or more and 3.10 μm or less, more preferably 1.20 μm or more and 2.70 μm or less, still more preferably 1 .30 μm or more and 2.30 μm or less, particularly preferably 1.60 μm or more and 2.00 μm or less. When Wdc is within the above range, it is possible to achieve excellent circuit linearity and high peel strength in a well-balanced manner while ensuring excellent transmission characteristics.

The roughened surface of the roughened copper foil preferably has a roughness curve with a root-mean-square height Rq of 0.290 μm or less, more preferably 0.030 μm or more and 0.260 μm or less, still more preferably 0.290 μm or less. 060 μm or more and 0.220 μm or less, particularly preferably 0.090 μm or more and 0.200 μm or less. When Rq is within the above range, it is possible to achieve even better transmission characteristics while maintaining excellent circuit linearity and high peel strength.

The thickness of the roughened copper foil is not particularly limited, but is preferably 0.1 μm or more and 210 μm or less, more preferably 0.3 μm or more and 105 μm or less, still more preferably 7 μm or more and 70 μm or less, and particularly preferably 9 μm or more and 35 μm or less. . The roughened copper foil of the present invention is not limited to the ordinary copper foil whose surface has been roughened, but the copper foil surface of the carrier-attached copper foil has been roughened or finely roughened. can be anything.

An example of the roughened copper foil of the present invention is shown in FIG. As shown in FIG. 5, the roughened copper foil of the present invention is obtained by subjecting a copper foil surface having predetermined undulations (for example, a deposition surface of an electrolytic copper foil) to a roughening treatment under desired low-roughening conditions. It can be produced preferably by carrying out to form fine roughened particles. Therefore, according to a preferred aspect of the present invention, the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the deposition surface side of the electrolytic copper foil. The roughened copper foil may have roughened surfaces on both sides, or may have a roughened surface only on one side. The roughened surface is typically provided with a plurality of roughened particles, and each of these roughened particles preferably consists of copper particles. The copper particles may consist of metallic copper, or may consist of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably carried out by forming roughening particles with copper or a copper alloy on the copper foil. The copper foil before the roughening treatment may be a non-roughened copper foil or a pre-roughened copper foil. The surface of the copper foil to be roughened preferably has a ten-point average roughness Rz measured in accordance with JIS B0601-1994 of 1.30 μm or more and 10.00 μm or less, more preferably It is 1.50 μm or more and 8.00 μm or less. Within the above range, it becomes easier to impart the surface profile required for the roughened copper foil of the present invention to the roughened surface.

The roughening treatment is performed, for example, in a copper sulfate solution containing a copper concentration of 7 g/L or more and 17 g/L or less and a sulfuric acid concentration of 50 g/L or more and 200 g/L or less at a temperature of 20 ° C. or more and 40 ° C. or less at 10 A / dm ² or more and 50 A. /dm ² or less. This electrolytic deposition is preferably carried out for 0.5 to 30 seconds, more preferably 1 to 30 seconds, and even more preferably 1 to 3 seconds. However, the roughened copper foil according to the present invention is not limited to the method described above, and may be manufactured by any method.

During the above electrolytic deposition, the following formula:
R _L =L/D _C
(Wherein, R _L is the liquid resistance index (mm L/mol), L is the distance between the electrodes (anode-cathode) (mm), and D _C is the charge carrier density (mol/L).)
The liquid resistance index _RL defined by is preferably 9.0 mm L / mol or more and 20.0 mm L / mol or less, and 11.0 mm L / mol or more and 17.0 mm L / mol or less is more preferred. By increasing the liquid resistance index _RL in this manner, the voltage in the entire system increases, and the voltage during the nodule formation reaction also increases. As a result of this affecting the shape of the bumps, the bumps can be preferably formed in a shape suitable for imparting the surface profile required for the roughened copper foil of the present invention. The charge carrier density _Dc can be calculated by totaling the product of each ion concentration and valence for all ions present in the plating solution. For example, when using a copper sulfate solution as the plating solution, the charge carrier density D _C is given by the following formula:
Dc=[H ⁺ ]×1+[Cu ²⁺ ]×2+[SO ₄ ²⁻ ]×2
(In the formula, [H ⁺ ] is the hydrogen ion concentration in the solution (mol/L), [Cu ²⁺ ] is the copper ion concentration in the solution (mol/L), and [SO ₄ ²⁻ ] is the sulfate ion in the solution. concentration (mol/L))
Calculated by

The relationship between liquid resistance index _RL and voltage is explained as follows. First, according to Ohm's law, the following formula:
V=ρ×L×I/S
(Wherein, V is the voltage, ρ is the specific resistance, L is the distance between the electrodes, I is the current, and S is the cross-sectional area between the electrodes)
is derived. That is, the voltage V is proportional to the specific resistance ρ, the inter-electrode distance L, and the current density (=I/S). Then, the resistivity ρ is inversely proportional to the charge carrier density _DC mentioned above. Therefore, if the current density is constant, increasing the liquid resistance index (proportional to the inter-electrode distance L and inversely proportional to the charge carrier density _DC ) will also increase the voltage. Therefore, it can be said that the liquid resistance index is an index that correlates with the resistance of the solution.

If desired, the roughened copper foil may be subjected to antirust treatment and may have an antirust treatment layer formed thereon. The antirust treatment preferably includes plating with zinc. The plating treatment using zinc may be either zinc plating treatment or zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, Co and Mo. For example, the antirust treatment layer further contains Mo in addition to Ni and Zn, so that the treated surface of the roughened copper foil has excellent adhesion to resin, chemical resistance, and heat resistance, and etching residue is removed. It becomes difficult to remain.

In the zinc-nickel alloy plating, Ni/(Zn+Ni), which is the ratio of the Ni deposition amount to the total amount of the Zn deposition amount and the Ni deposition amount, is preferably 0.3 or more and 0.9 or less, more preferably It is 0.4 or more and 0.9 or less, more preferably 0.4 or more and 0.8 or less. The total amount of Zn and Ni deposited in the zinc-nickel alloy plating is preferably 8 mg/m ² or more and 160 mg/m ² or less, more preferably 13 mg/m ² or more and 130 mg/m ² or less, and still more preferably 19 mg/m ² . 80 mg/ ^m2 or less. On the other hand, in zinc-nickel-molybdenum alloy plating, Ni/(Zn+Ni+Mo), which is the ratio of the Ni deposition amount to the total amount of the Zn deposition amount, the Ni deposition amount and the Mo deposition amount, is 0.20 or more and 0.20 to 0.20. It is preferably 80 or less, more preferably 0.25 or more and 0.75 or less, still more preferably 0.30 or more and 0.65 or less. In addition, the total deposition amount of Zn, Ni and Mo in the zinc-nickel-molybdenum alloy plating is preferably 10 mg/m ² or more and 200 mg/m ² or less, more preferably 15 mg/m ² or more and 150 mg/m ² or less, further preferably 20 mg/m ² or more and 90 mg/m ² or less. The amounts of Zn, Ni, and Mo deposited were obtained by dissolving a predetermined area (for example, 25 cm ² ) on the roughened surface of the roughened copper foil with acid, and measuring the concentration of each element in the resulting solution by ICP emission spectrometry. It can be calculated by analyzing based on the law.

The antirust treatment preferably further includes chromate treatment, and this chromate treatment is more preferably performed on the surface of the zinc-containing plating after the plating treatment using zinc. By doing so, the rust resistance can be further improved. A particularly preferred antirust treatment is a combination of zinc-nickel alloy plating treatment (or zinc-nickel-molybdenum alloy plating treatment) and subsequent chromate treatment.

If desired, the surface of the roughened copper foil may be treated with a silane coupling agent to form a silane coupling agent-treated layer. As a result, moisture resistance, chemical resistance, adhesion to adhesives and the like can be improved. The silane coupling agent-treated layer can be formed by appropriately diluting a silane coupling agent, coating it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. amino-functional silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacrylic acrylic functional silane coupling agents such as roxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, or imidazole functional silane coupling agents such as imidazole silane, or triazine functional silane coupling agents such as triazine silane, and the like. is mentioned.

For the reasons described above, the roughened copper foil preferably has an anticorrosive layer and/or a silane coupling agent-treated layer on the roughened surface, more preferably an anticorrosive layer and a silane coupling agent-treated layer. Provide both. When a rust-preventive treatment layer and/or a silane coupling agent-treated layer is formed on the roughened surface, each numerical value of the roughness parameter and waviness parameter in this specification is It means a numerical value obtained by measuring the surface of the roughened copper foil after the agent-treated layer is formed. In addition, the anticorrosion treatment layer and the silane coupling agent treatment layer may be formed not only on the roughened surface side of the roughened copper foil, but also on the side where the roughened surface is not formed.

Copper-Clad Laminate The roughened copper foil of the present invention is preferably used for producing a copper-clad laminate for printed wiring boards. That is, according to a preferred aspect of the present invention, there is provided a copper-clad laminate comprising the roughened copper foil. By using the roughened copper foil of the present invention, it is possible to achieve both excellent transmission characteristics and high peel strength in copper-clad laminates. This copper-clad laminate comprises the roughened copper foil of the present invention and a resin layer provided in close contact with the roughened surface of the roughened copper foil. The roughened copper foil may be provided on one side of the resin layer, or may be provided on both sides. The resin layer comprises resin, preferably insulating resin. The resin layer is preferably prepreg and/or resin sheet. Prepreg is a general term for composite materials in which synthetic resin is impregnated into a base material such as a synthetic resin plate, a glass plate, a glass woven fabric, a glass non-woven fabric, or paper. Preferred examples of insulating resins include epoxy resins, cyanate resins, bismaleimide triazine resins (BT resins), polyphenylene ether resins, and phenol resins. Examples of the insulating resin forming the resin sheet include insulating resins such as epoxy resins, polyimide resins, and polyester resins. In addition, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation. Although the thickness of the resin layer is not particularly limited, it is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and still more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and/or a resin sheet may be provided on the roughened copper foil in advance via a primer resin layer that is applied to the surface of the copper foil.

Printed Wiring Board The roughened copper foil of the present invention is preferably used for manufacturing printed wiring boards. That is, according to a preferred aspect of the present invention, there is provided a printed wiring board comprising the roughened copper foil. By using the roughened copper foil of the present invention, it is possible to achieve both excellent transmission characteristics and high peel strength in a printed wiring board. The printed wiring board according to this aspect includes a layer structure in which a resin layer and a copper layer are laminated. The copper layer is a layer derived from the roughened copper foil of the present invention. Also, the resin layer is as described above for the copper-clad laminate. In any case, a known layer structure can be adopted for the printed wiring board. Specific examples of printed wiring boards include a single-sided or double-sided printed wiring board formed by bonding the roughened copper foil of the present invention to one or both sides of a prepreg to form a cured laminate, and then forming a circuit on the printed wiring board. A multilayer printed wiring board etc. are mentioned. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc., in which the roughened copper foil of the present invention is formed on a resin film to form a circuit. As another specific example, a resin-coated copper foil (RCC) is formed by applying the above resin layer to the roughened copper foil of the present invention, and the resin layer is used as an insulating adhesive layer and laminated on the above printed circuit board. After that, the roughened copper foil is used as all or part of the wiring layer, and the circuit is formed by the modified semi-additive method (MSAP), the subtractive method, etc., and the roughened copper foil is removed. A build-up wiring board in which a circuit is formed by a semi-additive method (SAP), and a direct build-up on wafer in which lamination of resin-coated copper foil on a semiconductor integrated circuit and circuit formation are alternately repeated.

The present invention will be explained more specifically by the following examples.

Examples 1-11
The roughened copper foil of the present invention was manufactured as follows.

(1) Production of Electrodeposited Copper Foil A sulfuric acid copper sulfate solution having the composition shown below was used as the copper electrolyte, a titanium electrode was used as the cathode, and a DSA (dimensionally stable anode) was used as the anode. Electrolysis was performed at a temperature of 45° C. and a current density of 55 A/dm ² to obtain an electrolytic copper foil having a thickness shown in Table 1. At this time, as the cathode, an electrode whose surface was polished with a buff having a count shown in Table 1 to adjust the surface roughness was used.
<Composition of sulfuric acid copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 300g/L
- Glue concentration: 5 mg / L
- Chlorine concentration: 30 mg / L

(2) Roughening treatment Of the electrode surface and deposition surface provided by the above-described electrodeposited copper foil, roughening was performed on the deposition surface side for Examples 1 to 6 and 11, and on the electrode surface side for Examples 7 to 10. A chemical treatment was performed. In addition, the deposition surface of the electrolytic copper foil used in Examples 1 to 6 and 11 and the electrode surface of the electrolytic copper foil used in Examples 7 to 10 were measured using a contact surface roughness meter in accordance with JIS B0601-1994. Table 1 shows the ten-point average roughness Rz measured.

For Examples 1 to 8, the following roughening treatment (first roughening treatment) was performed. This roughening treatment is performed in a copper electrolytic solution for roughening treatment (copper concentration: 7 g / L or more and 17 g / L or less, sulfuric acid concentration: 50 g / L or more and 200 g / L or less, liquid temperature: 30 ° C.) for each example Electrolysis was carried out under the conditions of liquid resistance index, current density and time shown in Table 1, followed by washing with water.

For Examples 9 to 11, the following first roughening treatment, second roughening treatment and third roughening treatment were performed in this order.
- The first roughening treatment is performed in a copper electrolytic solution for roughening treatment (copper concentration: 7 g / L or more and 17 g / L or less, sulfuric acid concentration: 50 g / L or more and 200 g / L or less, liquid temperature: 30 ° C.) Table 1 Electrolysis was carried out under the liquid resistance index, current density and time conditions shown in , followed by washing with water.
- The second roughening treatment is performed by electrolysis under the conditions of liquid resistance index, current density and time shown in Table 1 in a copper electrolytic solution for roughening treatment having the same composition as the first roughening treatment, and washing with water. gone.
- The third roughening treatment is performed in a copper electrolytic solution for roughening treatment (copper concentration: 65 g / L or more and 80 g / L or less, sulfuric acid concentration: 50 g / L or more and 200 g / L or less, liquid temperature: 45 ° C.) Table 1 Electrolysis was carried out under the liquid resistance index, current density and time conditions shown in , followed by washing with water.

(3) Anticorrosion Treatment The antirust treatment shown in Table 1 was performed on the electrolytic copper foil after the roughening treatment. As this rust prevention treatment, for Examples 1 and 5 to 8, a pyrophosphate bath was used on the roughened surface of the electrolytic copper foil, with a potassium pyrophosphate concentration of 100 g / L, a zinc concentration of 1 g / L, nickel Rust prevention treatment A (zinc-nickel-molybdenum system rust prevention treatment) was performed at a concentration of 2 g/L, a molybdenum concentration of 1 g/L, a liquid temperature of 40°C, and a current density of 0.5 A/dm ² . In addition, a pyrophosphate bath was applied to the surface of the electrodeposited copper foil that had not been roughened, and the concentration of potassium pyrophosphate was 80 g/L, the concentration of zinc was 0.2 g/L, the concentration of nickel was 2 g/L, the liquid temperature was 40°C. Antirust treatment B (zinc-nickel antirust treatment) was performed at a current density of 0.5 A/dm ² . On the other hand, in Examples 2 to 4 and 9 to 11, both surfaces of the electrolytic copper foil were subjected to antirust treatment B under the same conditions as the surface of the electrolytic copper foil not subjected to roughening treatment in Examples 1 and 5 to 8. gone.

(4) Chromate Treatment Chromate treatment was performed on both surfaces of the antirust-treated electrolytic copper foil to form a chromate layer on the antirust treatment layer. This chromate treatment was performed under the conditions of a chromic acid concentration of 1 g/L, a pH of 11, a liquid temperature of 25° C. and a current density of 1 A/dm ² .

(5) Silane Coupling Agent Treatment The chromate-treated copper foil was washed with water and then immediately treated with a silane coupling agent to adsorb the silane coupling agent onto the chromate layer on the roughened surface. This silane coupling agent treatment was carried out by spraying a solution of a silane coupling agent using pure water as a solvent onto the roughened surface by showering for adsorption treatment. As the silane coupling agent, 3-aminopropyltrimethoxysilane was used in Examples 1, 3, 4 and 6-8, and 3-glycidoxypropyltrimethoxysilane was used in Examples 2, 5 and 9-11. The concentration of the silane coupling agent was 3 g/L in each case. After adsorption of the silane coupling agent, water was finally evaporated by an electric heater to obtain a roughened copper foil with a predetermined thickness.

Evaluation Various evaluations shown below were performed on the manufactured roughened copper foil.

<Surface quality parameters of roughened surface>
By surface roughness analysis using a laser microscope (OLS-5000 manufactured by Olympus Corporation), the roughened surface of the roughened copper foil was measured according to JIS B0601-2013. At this time, as shown in Table 2, the roughness parameters (Rdc, Rku, Rc and Rq) were measured with a measurement magnification of 200 times (objective lens magnification of 100 times and optical zoom of 2 times), and the waviness parameters (Wdc, Wt and Wp ), as shown in Table 3, the measurement was performed with a measurement magnification of 20 times (objective lens magnification of 20 times). Other specific measurement conditions were as shown in Tables 2 and 3. The obtained surface profile of the roughened surface was analyzed according to the conditions shown in Tables 2 and 3, and Rdc, Rku, Rc, Rq, Wdc, Wt and Wp were calculated. Also, Rdc/Rku was calculated based on the obtained Rdc and Rku values. The results were as shown in Table 4.

<Measurement of element adhesion amount in antirust treatment layer>
A region of 25 cm ² (5 cm × 5 cm) on the roughened surface of the roughened copper foil was dissolved with acid, and the concentrations of Zn, Ni and Mo in the resulting solution were analyzed by ICP emission spectrometry. Zn adhesion amount, Ni adhesion amount and Mo adhesion amount were measured. The results were as shown in Table 4.

<Preparation of copper-clad laminate>
Two prepregs (thickness: 100 μm) mainly composed of polyphenylene ether, triallyl isocyanurate, and bismaleimide resin were prepared and stacked as insulating substrates. The manufactured surface-treated copper foil was laminated on the stacked prepreg so that the roughened surface was in contact with the prepreg, and pressed at 32 kgf/cm ² and 205° C. for 120 minutes to obtain a 34 cm × 34 cm copper clad. A laminate was produced.

<Circuit linearity>
Circuit linearity was evaluated as follows. First, for Examples 4 to 7, etching was performed on the copper-foil-side surface of the above-described copper-clad laminate until the thickness of the copper foil reached 12 μm. For Examples 1 to 11, a dry film was attached to the surface of the copper-clad laminate on the copper foil side, followed by exposure and development to form an etching resist. By treating with a copper chloride etchant, copper was dissolved and removed from between the resists to form linear circuits each having a width of 300 μm, a height of 12 μm, and a length of 10 cm or 15 cm (six in total). The linear circuit thus obtained was observed with an optical microscope, and the circuit width was measured by randomly selecting 30 points per circuit. An average value and a standard deviation were calculated for the obtained 30 sets of circuit width data, and the coefficient of variation (%) for each circuit was calculated by dividing the standard deviation by the average value. The average value of the variation coefficients in the six circuits was obtained and used as the circuit width variation coefficient in each example. The quality of the obtained circuit width variation coefficient was evaluated according to the following criteria. The results were as shown in Table 4.
<Circuit Width Variation Coefficient Evaluation Criteria>
-Good: Circuit width variation coefficient is 1.50% or less -Bad: Circuit width variation coefficient is over 1.50%

<Peel strength between copper foil and substrate>
In order to evaluate the adhesion between the roughened copper foil and the insulating substrate, the normal peel strength was measured as follows. First, for Examples 4 to 7, etching was performed on the copper-foil-side surface of the above-described copper-clad laminate until the thickness of the copper foil reached 12 μm. For Examples 1 to 11, circuit formation was performed on the copper-clad laminate by an etching method to produce a test substrate having a straight circuit with a width of 3 mm. The linear circuit thus obtained was peeled off from the insulating substrate according to JIS C 5016-1994 A method (90° peeling), and the normal peel strength (kgf/cm) was measured. The quality of the normal peel strength obtained was evaluated according to the following criteria. The results were as shown in Table 4.
<Normal state peel strength evaluation criteria>
-Good: normal peel strength is 0.30 kgf / cm or more -Poor: normal peel strength is less than 0.30 kgf / cm

(c) Transmission characteristics A base material for high frequency (MEGTRON6N manufactured by Panasonic) was prepared as an insulating resin base material. A roughened copper foil is laminated on both sides of this insulating resin substrate so that the roughened surface is in contact with the insulating resin substrate, and a vacuum press is used at a temperature of 190 ° C. for a pressing time of 120 minutes. to obtain a copper-clad laminate having an insulation thickness of 136 μm. After that, the copper-clad laminate was subjected to an etching process to obtain a transmission loss measuring board on which microstrip lines were formed so as to have a characteristic impedance of 50Ω. The transmission loss (dB/cm) at 28 GHz was measured on the obtained transmission loss measuring board using a network analyzer (N5225B manufactured by Keysight Technologies). The quality of the obtained transmission loss was evaluated according to the following criteria. The results were as shown in Table 4.
<Transmission loss evaluation criteria>
-Good: Transmission loss is -0.33 dB/cm or more -Bad: Transmission loss is less than -0.33 dB/cm

Claims

A roughened copper foil having a roughened surface on at least one side,
In the roughened surface, Rdc/Rku, which is the ratio of the cutting level difference Rdc of the roughness curve to the kurtosis Rku of the roughness curve, is 0.180 μm or less, and the maximum cross-sectional height Wt of the undulation curve is 2.0 μm. 50 μm or more and 10.00 μm or less,
The Rku is a value measured in accordance with JIS B0601-2013 under the conditions of a magnification of 200, a cutoff wavelength of 0.3 μm with a cutoff value λs, and a cutoff wavelength of 5 μm with a cutoff value λc,
The Rdc is measured in accordance with JIS B0601-2013 under the conditions of a magnification of 200, a cutoff wavelength of 0.3 μm with a cutoff value λs, and a cutoff wavelength of 5 μm with a cutoff value λc. is the value obtained as the difference (c(Rmr1)-c(Rmr2)) in the cutting level c in the height direction between the load length ratio (Rmr1) of 20% and the load length ratio (Rmr2) of 80%;
The Wt is a value measured in accordance with JIS B0601-2013 under the conditions of a magnification of 20 times, a cutoff wavelength of 5 μm with a cutoff value λc, and no cutoff with a cutoff value λf. Copper foil.
The roughened copper foil according to claim 1, wherein the roughened surface has a maximum cross-sectional height Wt of 2.90 µm or more and 10.00 µm or less.
The roughened copper foil according to claim 1 or 2, wherein the roughened surface has a cutting level difference Rdc of 0.45 µm or less.
The roughened surface has a maximum peak height Wp of an undulating curve of 1.00 μm or more and 6.00 μm or less, and the Wp is cut off by a cutoff value λc at a magnification of 20 times in accordance with JIS B0601-2013. 3. The roughened copper foil according to claim 1 or 2, which is a value measured under conditions where a wavelength of 5 μm and cutoff with a cutoff value λf are not performed.
The roughened surface has an average height Rc of roughness curve elements of 0.70 μm or less, and the Rc is a cutoff wavelength of 0 at a magnification of 200 and a cutoff value λs in accordance with JIS B0601-2013. The roughened copper foil according to claim 1 or 2, which is a value measured under conditions of .3 µm and a cutoff wavelength of 5 µm with a cutoff value λc.
The roughened surface has a cutting level difference Wdc of the undulating curve of 1.20 μm or more and 3.10 μm or less, and the Wdc is cut off by a cutoff value λc at a magnification of 20 times in accordance with JIS B0601-2013. Height direction between load length ratio (Wmr1) 20% and load length ratio (Wmr2) 80% in the undulation curve measured under the condition that the wavelength is 5 μm and the cutoff value λf is not cut off. 3. The roughened copper foil according to claim 1, which is a value obtained as a difference (c(Wmr1)-c(Wmr2)) of the cutting level c.
The roughened surface has a root-mean-square height Rq of the roughness curve of 0.290 μm or less, and the Rq is a cutoff wavelength with a cutoff value λs at a magnification of 200 in accordance with JIS B0601-2013. 3. The roughened copper foil according to claim 1, which is a value measured under conditions of 0.3 μm and a cutoff wavelength of 5 μm with a cutoff value λc.
The roughened copper foil according to claim 1 or 2, wherein the roughened surface has a kurtosis Rku of 1.30 or more and 8.00 or less.
The roughened copper foil according to claim 1 or 2, wherein the roughened surface is provided with an anticorrosive layer and/or a silane coupling agent-treated layer.
The roughened copper foil according to claim 1 or 2, wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the deposition surface side of the electrolytic copper foil.
A copper clad laminate comprising the roughened copper foil according to claim 1 or 2.
A printed wiring board comprising the roughened copper foil according to claim 1 or 2.