Roughened copper foil, copper-clad laminate, and printed circuit board

Abstract

Provided is a roughened copper foil that can achieve both excellent transmission characteristics and high peel strength in the case of a copper-clad laminate and / or printed circuit board. The roughened copper foil has a roughened surface on at least one side. The microtip particle volume calculated by the formula (Vmp+Vmc) / Spd from the solid volume Vmp of the protruding peak portions, the solid volume Vmc of the central portions, and the peak apex density Spd of the roughened surface is 1.300 μm 3 or less, and the cross-sectional height difference Rdc is 0.95 μm or more. Vmp, Vmc, and Spd are values measured in accordance with ISO 25178, and Rdc is a value obtained in the form of the difference in the cross-sectional height c in the height direction at load length ratios of 20% and 80% in accordance with JIS B0601-2013.

Description

Technical Field

[0001] This invention relates to roughened copper foil, copper-clad laminates, and printed circuit boards. Background Technology

[0002] In the manufacturing process of printed circuit boards (PCBs), copper foil is widely used in the form of copper-clad laminates bonded to an insulating resin substrate. To prevent wiring stripping during PCB manufacturing, a high degree of adhesion between the copper foil and the insulating resin substrate is desirable. Therefore, in typical PCB manufacturing copper foil, the bonding surface is roughened to create an uneven surface composed of fine copper particles. This uneven surface is then pressed into the insulating resin substrate to provide an anchoring effect, thereby improving adhesion.

[0003] For example, a surface-treated copper foil disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2018-172785) has a copper foil and a roughening treatment layer on at least one surface of the copper foil. The arithmetic mean roughness Ra of the roughening treatment layer side surface is 0.08 μm or more and 0.20 μm or less, and the gloss TD (width direction) of the roughening treatment layer side surface is 70% or less. According to such a surface-treated copper foil, the shedding of roughening particles provided on the surface of the copper foil can be well suppressed, and the occurrence of wrinkles and streaks when bonded to an insulating substrate can be well suppressed.

[0004] However, with the increasing functionality of portable electronic devices in recent years, and the need for high-speed processing of large amounts of data, both digital and analog signals are increasingly being transmitted at higher frequencies, demanding printed circuit boards (PCBs) suitable for high-frequency applications. For such high-frequency PCBs, reducing transmission loss is crucial to ensure undegraded transmission of high-frequency signals. PCBs consist of copper foil with fabricated wiring patterns and an insulating substrate; however, the main losses in transmission loss include conductor loss caused by the copper foil and dielectric loss caused by the insulating substrate.

[0005] In this regard, a roughened copper foil that achieves a reduction in transmission loss has been proposed. For example, Patent Document 2 (Japanese Patent Application Publication No. 2015-148011) discloses a surface-treated copper foil with low signal transmission loss and a laminate using the surface-treated copper foil, wherein the surface skewness Rsk of the copper foil surface, according to JIS B0601-2001, is controlled within the specified range of -0.35 or higher and 0.53 or lower through surface treatment.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-172785

[0009] Patent Document 2: Japanese Patent Application Publication No. 2015-148011 Summary of the Invention

[0010] As mentioned above, in recent years, there has been a demand for improved transmission characteristics (high-frequency characteristics) of printed circuit boards. To address this demand, attempts have been made to further roughen the bonding surface between the copper foil and the insulating resin substrate. That is, to reduce the unevenness of the copper foil surface, which is a major cause of increased transmission loss, it is considered to finely roughen the surface of the copper foil with low waviness (e.g., the surface of double-sided smooth foil, the electrode surface of electrolytic copper foil). However, when using such roughened copper foil in the processing of copper-clad laminates and / or the manufacture of printed circuit boards, problems such as low peel strength and poor adhesion reliability between the copper foil and the substrate are generally encountered.

[0011] The inventors have obtained the following insight: By controlling the volume of tiny tip particles and the cross-sectional height difference Rdc, calculated based on the solid volume Vmp of the protruding peak, the solid volume Vmc of the center, and the peak density Spd, within a specified range, excellent transmission characteristics and high peel strength can be achieved in copper-clad laminates and / or printed circuit boards manufactured using it.

[0012] Therefore, the object of the present invention is to provide a roughened copper foil that can achieve both excellent transport characteristics and high peel strength when used in copper-clad laminates and / or printed circuit boards.

[0013] According to the present invention, the following methods are provided.

[0014] [Method 1]

[0015] A roughened copper foil having a roughened surface on at least one side.

[0016] The solid volume Vmp (μm) of the roughened surface based on the protruding peaks per unit area. 3 / μm 2 ), the solid volume Vmc (μm) at the center of each unit area 3 / μm 2 ) and peak density Spd (number of peaks / μm) per unit area 2 The volume of the tiny tip particles, calculated using the formula (Vmp+Vmc) / Spd, is 1.300 μm. 3 The number of individual sections is less than 1, and the cross-sectional height difference Rdc is greater than 0.95μm.

[0017] The values ​​of Vmp, Vmc, and Spd were measured according to ISO 25178 under the conditions of a magnification of 200x, a cutoff wavelength of 0.3μm based on an S-filter, and a cutoff wavelength of 5μm based on an L-filter.

[0018] The Rdc mentioned is the value obtained in the roughness curve measured according to JIS B0601-2013 under the conditions of 20x magnification, no cutoff based on cutoff value λs, and a cutoff wavelength of 320μm based on cutoff value λc, in the form of the difference of the cross section height c in the height direction at the load length ratio (Rmr1) 20% and the load length ratio (Rmr2) 80% (c(Rmr1)-c(Rmr2)).

[0019] [Method 2]

[0020] According to the roughening treatment of copper foil in Method 1, the cross-sectional height difference Rdc of the roughened surface is more than 1.10 μm and less than 20.00 μm.

[0021] [Method 3]

[0022] According to method 1 or 2, the roughening treatment of copper foil, wherein the solid volume Vmc of the central portion per unit area of ​​the roughened surface is 0.360 μm. 3 / μm 2 the following.

[0023] [Method 4]

[0024] The roughened copper foil according to any one of methods 1 to 3, wherein the sum of the solid volume Vmp of the protruding peak of the roughened surface and the solid volume Vmc of the central portion, i.e., Vmp + Vmc, is 0.380 μm. 3 / μm 2 the following.

[0025] [Method 5]

[0026] The roughened copper foil according to any one of methods 1 to 4, wherein the interface expansion area ratio Sdr of the roughened surface is less than 70%, and the Sdr is a value measured according to ISO 25178 under the conditions of magnification of 200 times, a cutoff wavelength of 0.3 μm based on the S filter and a cutoff wavelength of 5 μm based on the L filter.

[0027] [Method 6]

[0028] The roughened copper foil according to any one of methods 1 to 5, wherein the horizontal difference Sk at the center of the roughened surface is 1.50 μm or more, and Sk is a value measured according to ISO 25178 at a magnification of 20x, without S-filter cutoff and with an L-filter cutoff wavelength of 320 μm.

[0029] [Method 7]

[0030] The roughened copper foil according to any one of methods 1 to 6, wherein the pole height Sxp of the roughened surface is 1.10 μm or more, and the Sxp is a value measured according to ISO 25178 at a magnification of 20x, without S-filter-based cutoff and with an L-filter-based cutoff wavelength of 320 μm.

[0031] [Method 8]

[0032] The roughened copper foil according to any one of methods 1 to 7, wherein the peak density Spd per unit area of ​​the roughened surface is 0.12 peaks / μm. 2 Above and 0.46 per μm 2 the following.

[0033] [Method 9]

[0034] The roughened copper foil according to any one of methods 1 to 8 further comprises a rust-preventive treatment layer and / or a silane coupling agent treatment layer on the roughened surface.

[0035] [Method 10]

[0036] The roughened copper foil according to any one of methods 1 to 9, wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface exists on the deposition surface side of the electrolytic copper foil.

[0037] [Method 11]

[0038] A copper-clad laminate comprising a roughened copper foil as described in any one of embodiments 1 to 10.

[0039] [Method 12]

[0040] A printed circuit board comprising a roughened copper foil as described in any one of embodiments 1 to 10. Attached Figure Description

[0041] Figure 1 A diagram of the load curve used to illustrate the roughness curve determined according to JIS B0601-2013.

[0042] Figure 2A graph used to illustrate the load length ratio Rmr(c) determined according to JIS B0601-2013.

[0043] Figure 3 This is a diagram used to illustrate the section height difference Rdc determined according to JIS B0601-2013.

[0044] Figure 4 A graph used to illustrate the load curve and load area ratio Smr(c) of a surface as determined according to ISO 25178.

[0045] Figure 5 A graph used to illustrate the load area ratio Smr1 that separates the prominent peak from the center, the load area ratio Smr2 that separates the prominent valley from the center, and the horizontal difference Sk of the center, as determined according to ISO 25178.

[0046] Figure 6 A diagram illustrating the solid volume Vmp of the prominent peak and the solid volume Vmc of the center, as determined according to ISO 25178.

[0047] Figure 7 This is a diagram used to illustrate the pole height Sxp as determined according to ISO 25178.

[0048] Figure 8 This diagram illustrates the surface roughness of the copper foil, including roughening particle components and waviness components.

[0049] Figure 9 This is a cross-sectional schematic diagram of roughened particles, used to illustrate the volume of tiny tip particles.

[0050] Figure 10 This is a schematic diagram illustrating an example of the roughening treatment of copper foil according to the present invention. Detailed Implementation

[0051] definition

[0052] The following shows the definitions of terms and / or parameters used to define this invention.

[0053] In this specification, "the load curve of the roughness curve" is as follows: Figure 1 As shown, this is a curve defined according to JIS B0601-2013, representing the proportion of the solid portion appearing when cutting the roughness curve at section height c as a function of c. That is, the load curve of the roughness curve can also be described as a curve representing the load length ratio Rmr(c) from 0% to 100%. The load length ratio Rmr(c) is as follows... Figure 2The figure shows the parameter, as determined by JIS B0601-2013, which represents the ratio of the load length to the evaluation length of the roughness curve element at section height c.

[0054] In this specification, "section height difference Rdc" or "Rdc" means... Figure 3 The figure shows the parameter (c(Rmr1)-c(Rmr2)) of the cross-sectional height c at two load length ratios Rmr1 and Rmr2 (where Rmr1 < Rmr2) in the load curve representing the roughness curve, as determined according to JIS B0601-2013. In this specification, Rmr1 is specified as 20% and Rmr2 as 80%, and Rdc is calculated.

[0055] In this specification, "surface load curve" refers to a curve, defined according to ISO 25178, representing the load area ratio from 0% to 100% height. The load area ratio is as follows: Figure 4 The figure shows parameters representing the area above a certain height c. The load-bearing area ratio at height c is equivalent to... Figure 4 Smr(c) in the example. Figure 5 The diagram shows a secant line drawn along the load curve, starting from a load area ratio of 0%, with the difference in load area ratios set to 40%. Moving this secant line from a load area ratio of 0%, the point where the slope of the secant line is flattest is called the central portion of the load curve. The straight line with the smallest sum of squares of deviations from the vertical axis relative to this central portion is called the equivalent straight line. The portion of the equivalent straight line encompassing the height range from 0% to 100% of the load area ratio is called the central portion. The portion higher than the central portion is called the prominent peak, and the portion lower than the central portion is called the prominent valley.

[0056] In this specification, "the loading area ratio Smr1 that separates the prominent peak from the center portion" is as follows: Figure 5 The figure shows the load area ratio (i.e., the load area ratio separating the center portion from the convex peak), a parameter defined according to ISO 25178, representing the intersection of the height of the upper part of the center portion and the load curve of the surface. In this specification, "load area ratio Smr2 separating the convex valley from the center portion" is as follows: Figure 5 The figure shows the load area ratio (i.e., the load area ratio that separates the center section from the protruding valley section) at the intersection of the height of the lower part of the center section and the load curve, as determined according to ISO 25178.

[0057] In this specification, "the horizontal difference Sk at the center" or "Sk" is a value obtained by subtracting the minimum height from the maximum height at the center, as measured according to ISO 25178. Figure 5The parameters shown are calculated based on the difference in height between the 0% and 100% load area ratios of the equivalent straight line.

[0058] In this specification, "the solid volume of the protruding peak Vmp" or "Vmp" is used as follows: Figure 6 The figure shows a parameter representing the volume of the prominent peak, measured according to ISO 25178. Additionally, in this specification, "the solid volume of the center, Vmc" or "Vmc" is used as follows: Figure 6 The figures shown represent the volume of the central portion, as determined according to ISO 25178. In this specification, the load area ratio Smr1, separating the central portion from the protruding peak, is specified as 10%, and the load area ratio Smr2, separating the central portion from the protruding valley, is specified as 80%, and Vmp and Vmc are calculated.

[0059] In this specification, "peak density Spd" or "Spd" is a parameter, measured according to ISO 25178, representing the number of peaks per unit area. Spd can be calculated by dividing the number of peaks contained in the profile surface by the projected area of ​​the profile surface. In this specification, only peaks greater than 5% of the maximum amplitude in the profile surface are counted to calculate Spd.

[0060] In this specification, "micro-apex particle volume" refers to the solid volume Vmp (μm) of the protruding peak per unit area. 3 / μm 2 ), the solid volume Vmc (μm) at the center of each unit area 3 / μm 2 ) and peak density Spd (number of peaks / μm) per unit area 2 The parameters are calculated using the formula (Vmp+Vmc) / Spd. Furthermore, in this specification, "Vmp+Vmc" refers to the solid volume Vmp (μm) of the protruding peak per unit area. 3 / μm 2 ) and the solid volume Vmc (μm) at the center of each unit area 3 / μm 2 The parameters are calculated by summing the sums of the parameters.

[0061] In this specification, "pole height Sxp" or "Sxp" means... Figure 7 The figure shows a parameter representing the height difference between the load area ratio p% and the load area ratio q%, as measured according to ISO 25178. Sxp represents the difference between the average surface area and the surface height after removing particularly high peaks in the surface. In this specification, the load area ratio p is specified as 2.5% and the load area ratio q is specified as 50%, and Sxp is calculated.

[0062] In this specification, "interface expansion area ratio Sdr" or "Sdr" is a parameter measured according to ISO 25178, expressing as a percentage how much the expanded area (surface area) of a defined region increases relative to the area of ​​the defined region. The smaller the value, the closer the surface shape is to a flat surface; the Sdr for a completely flat surface is 0%. On the other hand, the larger the value, the more uneven the surface shape is.

[0063] Rdc can be calculated by measuring the surface profile of a specified measurement length on the roughened surface using a commercially available laser microscope. Furthermore, Vmp, Vmc, Spd, Sdr, Sk, and Sxp can be calculated separately by measuring the surface profile of a specified measurement area on the roughened surface using a commercially available laser microscope. In this specification, Vmp, Vmc, Spd, and Sdr are measured at a magnification of 200x, a cutoff wavelength of 0.3 μm based on an S-filter, and a cutoff wavelength of 5 μm based on an L-filter. On the other hand, Rdc is measured at a magnification of 20x, without cutoff based on the cutoff value λs, and with a cutoff wavelength of 320 μm based on the cutoff value λc. Sk and Sxp are measured at a magnification of 20x, without cutoff based on an S-filter, and with a cutoff wavelength of 320 μm based on an L-filter. It should be noted that when using both an objective lens and optical zoom in measurements using a laser microscope, the aforementioned magnification is equivalent to the value obtained by multiplying the objective lens magnification by the optical zoom magnification. For example, with an objective lens magnification of 100x and an optical zoom magnification of 2x, the magnification is 200x (=100×2). Furthermore, preferred measurement and analysis conditions for surface profiles using a laser microscope are shown in the embodiments described later.

[0064] In this specification, the “electrode surface” of the electrolytic copper foil refers to the surface that contacts the cathode during the manufacturing process of the electrolytic copper foil.

[0065] In this specification, the “deposition surface” of electrolytic copper foil refers to the surface on which electrolytic copper is deposited during the manufacturing of electrolytic copper foil, that is, the surface that is not in contact with the cathode.

[0066] Roughening treatment of copper foil

[0067] 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. The solid volume Vmp (μm) of the roughened surface based on the protruding peaks per unit area is... 3 / μm 2 ), the solid volume Vmc (μm) at the center of each unit area 3 / μm 2 ) and peak density Spd (number of peaks / μm) per unit area 2The volume of the tiny tip particles, calculated using the formula (Vmp+Vmc) / Spd, is 1.300 μm. 3 / less. In addition, the cross-sectional height difference Rdc of the roughened surface is 0.95μm or more. It can be seen that by controlling the volume of the tiny tip particles and the cross-sectional height difference Rdc within a specified range on the surface of the roughened copper foil, it is possible to achieve both excellent transmission characteristics (high frequency characteristics) and high peel strength (e.g., normal peel strength and wet peel strength) in copper clad laminates and / or printed circuit boards manufactured using it.

[0068] Excellent transmission characteristics and high peel strength are inherently difficult to achieve simultaneously. This is because: to obtain excellent transmission characteristics, the surface roughness of the copper foil needs to be reduced, while to obtain high peel strength, the surface roughness of the copper foil needs to be increased; the two are in a trade-off relationship. Here, as... Figure 8 As shown, the roughness of the copper foil surface includes a "roughening particle component" and a "wrinkle component" with a longer period than the roughening particle component. Generally, in order to obtain excellent transmission characteristics, it is considered to perform fine roughening treatment on the copper foil surface with low wrinkle (e.g., the surface of double-sided smooth foil, the electrode surface of electrolytic copper foil) to form small roughening particles. However, when using such roughened copper foil to manufacture copper-clad laminates and / or printed circuit boards, the peel strength between the copper foil and the substrate is usually reduced.

[0069] To address this issue, the inventors investigated the effects of roughened particles and waviness on the surface of copper foil on transmission characteristics and peel strength. The results showed that, contrary to expectations, the waviness composition of the copper foil did not significantly affect transmission characteristics; rather, the size of the roughened particles was the primary factor influencing transmission characteristics. Furthermore, the inventors discovered that by miniaturizing the protrusions (roughened particles) to improve transmission characteristics and compensating for insufficient adhesion with a copper foil waviness that has minimal impact on transmission characteristics, it is possible to achieve both excellent transmission characteristics and the adhesion reliability resulting from high peel strength. Specifically, they found that by setting the volume of the tiny tip particles, which is related to the volume of the tiny protrusions (roughened particles) affecting transmission characteristics, to 1.300 μm… 3 Excellent transmission characteristics can be achieved with a minimum of / particles. Furthermore, it was found that by setting the cross-sectional height difference Rdc, which reflects the height of the roughened surface over a wide range, to 0.95 μm or more, even small roughened particles that would otherwise be difficult to guarantee peel strength can achieve high peel strength between the copper foil and the substrate by utilizing the waviness of the copper foil.

[0070] The mechanism by which controlling the volume of tiny tip particles can improve transport characteristics is not necessarily determined, but it can be considered as follows. Here, a cross-sectional schematic diagram of the protrusions (roughened particles) that distinguish the boundary between the central portion and the protruding valley is shown. Figure 9 .like Figure 9 As shown, the volume of the portion formed by the central part and the peak of the protrusion per unit area (excluding the lower part of the protrusion corresponding to the valley) is equivalent to Vmp + Vmc. Furthermore, since the peak density Spd represents the number of protrusions per unit area, therefore... Figure 9 As shown, the value obtained by dividing Vmp+Vmc by Spd (=(Vmp+Vmc) / Spd) corresponds to the volume of the tiny tip particle of each protrusion. In this respect, assuming two roughened surfaces with the same Spd (i.e., the same number of protrusions per unit area) and different Vmp+Vmc, the roughened surface with a smaller Vmp+Vmc has smaller protrusion sizes, thus exhibiting superior transmission characteristics. On the other hand, assuming two roughened surfaces with the same Vmp+Vmc (i.e., the same volume of protrusions per unit area) but different Spd, the roughened surface with a larger Spd has superior transmission characteristics because the same volume is distributed among most protrusions, i.e., the size of each protrusion is smaller. Therefore, by controlling the volume of the tiny tip particle to a smaller value, transmission characteristics can be improved.

[0071] The roughening particle composition and waviness composition of the copper foil surface, which affect transmission characteristics and / or peel strength, can be distinguished by flexibly using the measurement magnification of a laser microscope, as well as S-filters and L-filters, or cutoff values ​​λs and λc. Specifically, by measuring the roughened surface at a high magnification of 200x, the fine irregularities of the roughened surface affecting transmission characteristics can be accurately evaluated. Furthermore, by performing measurements under conditions of a cutoff wavelength of 0.3 μm based on an S-filter and a cutoff wavelength of 5 μm based on an L-filter, parameters of the roughening particle composition whose influence on waviness is suppressed can be obtained. Therefore, it can be said that the micro-tip particle volume, Vmp, Vmc, Vmp+Vmc, Spd, and Sdr in this invention accurately reflect the parameters of the roughened particles on the copper foil surface, and by using these indicators, transmission characteristics can be accurately evaluated. In contrast, by measuring the roughened surface at a low magnification of 20x, the overall height (waviness) of the roughened surface affecting sealing reliability can be broadly evaluated. Furthermore, by measuring the roughened surface without applying a cutoff value of λs or an S-filter-based cutoff, and with a cutoff value of λc or an L-filter-based cutoff wavelength of 320 μm, parameters reflecting both the roughening particle composition and the waviness composition of the roughened surface can be obtained. Therefore, Rdc, Sk, and Sxp in this invention are parameters that reflect not only the roughening particle composition of the copper foil surface but also the waviness composition. By using these indicators, peel strength can be accurately evaluated.

[0072] The cross-sectional height difference Rdc of the roughened surface of the roughened copper foil is 0.95 μm or more, preferably 1.10 μm or more and 20.00 μm or less, more preferably 1.15 μm or more and 12.00 μm or less, even more preferably 1.20 μm or more and 6.00 μm or less, and particularly preferably 1.25 μm or more and 4.00 μm or less. When Rdc is within the above range, excellent transmission characteristics are ensured while efficient anchoring and high peel strength are achieved.

[0073] The volume of the tiny tip particles on the roughened surface of the roughened copper foil is 1.300 μm. 3 / or less, preferably 0.300μm 3 / or more and 1.300μm 3 / or less, preferably 0.400 μm 3 / or more and 1.300μm 3 / or less, further preferably 0.500μm 3 / or more and 1.300μm 3 / or less, particularly preferably 0.500μm 3 / or more and 1.200μm3 / or less. When the particle size is within the above range, excellent transport characteristics can be achieved while maintaining high peel strength.

[0074] The solid volume Vmc of the center of the roughened surface of the roughened copper foil is preferably 0.360 μm. 3 / μm 2 The following is more preferably 0.040 μm 3 / μm 2 Above and 0.320μm 3 / μm 2 Hereinafter, 0.070 μm is further preferred. 3 / μm 2 Above and 0.290μm 3 / μm 2 Hereinafter, 0.100 μm is particularly preferred. 3 / μm 2 Above and 0.260μm 3 / μm 2 The preferred value is 0.130 μm. 3 / μm 2 Above and 0.230μm 3 / μm 2 Below. When Vmc is within the above range, it is easy to control the volume of tiny tip particles within the above range, and while achieving high peel strength, it is possible to achieve better transport characteristics.

[0075] The sum of the solid volume Vmp of the protruding peak and the solid volume Vmc of the center of the roughened surface of the copper foil, i.e., Vmp + Vmc, is preferably 0.380 μm. 3 / μm 2 The following is more preferably 0.050 μm 3 / μm 2 Above and 0.340μm 3 / μm 2 Hereinafter, 0.090 μm is further preferred. 3 / μm 2 Above and 0.310μm 3 / μm 2 The following is particularly preferred: 0.130 μm 3 / μm 2 Above and 0.280μm 3 / μm 2 The preferred value is 0.140 μm. 3 / μm 2 Above and 0.250μm 3 / μm 2The following applies. When Vmp+Vmc is within the above range, it is easy to control the volume of tiny tip particles within the above range, achieving both high peel strength and superior transport characteristics.

[0076] The peak density Spd per unit area of ​​the roughened surface of the roughened copper foil is preferably 0.12 peaks / μm. 2 Above and 0.46 per μm 2 Below, 0.13 particles / μm is more preferred. 2 Above and 0.44 per μm 2 Hereinafter, 0.14 particles / μm is further preferred. 2 Above and 0.37 cells / μm 2 The following is particularly preferred: 0.15 particles / μm 2 Above and 0.31 cells / μm 2 The optimal value is 0.16 particles / μm. 2 Above and 0.28 cells / μm 2 Below. When the Spd is within the above range, it is easy to control the volume of tiny tip particles within the above range, achieving both high peel strength and superior transport characteristics.

[0077] The interface expansion area ratio (Sdr) of the roughened surface of the roughened copper foil is preferably 70% or less, more preferably 5% or more and 65% or less, even more preferably 10% or more and 60% or less, particularly preferably 15% or more and 55% or less, and most preferably 20% or more and 50% or less. When the Sdr is within the above range, a textured shape with uneven surfaces is formed, which is conducive to achieving better transport characteristics, while ensuring high peel strength.

[0078] The horizontal difference Sk at the center of the roughened surface of the roughened copper foil is preferably 1.50 μm or more, more preferably 1.58 μm or more and 20.00 μm or less, even more preferably 1.65 μm or more and 12.00 μm or less, particularly preferably 1.70 μm or more and 8.00 μm or less, and most preferably 2.00 μm or more and 6.00 μm or less. When Sk is within the above range, excellent transport characteristics are achieved, while anchoring effect is efficiently exerted and higher peel strength is realized.

[0079] The pole height Sxp of the roughened surface of the roughened copper foil is preferably 1.10 μm or more, more preferably 1.20 μm or more and 20.00 μm or less, even more preferably 1.30 μm or more and 12.00 μm or less, particularly preferably 1.40 μm or more and 8.00 μm or less, and most preferably 1.70 μm or more and 6.00 μm or less. When the pole height Sxp is within the above range, excellent transmission characteristics can be achieved while efficiently exerting the anchoring effect and realizing higher peel strength.

[0080] There is no particular limitation on the thickness of the roughened copper foil, but it is preferably 0.1 μm or more and 210 μm or less, more preferably 0.3 μm or more and 105 μm or less. It should be noted that the roughened copper foil of the present invention is not limited to roughening the surface of ordinary copper foil, but can also be formed by roughening and / or micro-roughening the surface of copper foil with a carrier copper foil.

[0081] Figure 10 An example of the roughening treatment of copper foil according to the present invention is shown. For example... Figure 10 As shown, the roughened copper foil of the present invention can preferably be manufactured by roughening the surface of a copper foil with a specified waviness (e.g., the deposited surface of an electrolytic copper foil) under desired low roughening conditions to form fine roughened particles. Therefore, according to a preferred embodiment of the present invention, the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the deposited surface side of the electrolytic copper foil. It should be noted that the roughened copper foil can be a copper foil with roughened surfaces on both sides, or a copper foil with a roughened surface on only one side. The roughened surface typically has multiple roughened particles, which are preferably formed from copper particles. The copper particles can be formed from metallic copper or from a copper alloy.

[0082] The roughening treatment for forming the roughened surface can more preferably be performed by forming roughening particles on the copper foil using copper or a copper alloy. The copper foil before roughening treatment can be an unroughened copper foil or a pre-roughened copper foil. The surface roughness Rz of the roughened copper foil, measured according to JIS B0601-1994, is preferably 1.50 μm or more and 20.00 μm or less, more preferably 2.00 μm or more and 10.00 μm or less. Within the above range, it is easy to impart the surface profile required by the roughened copper foil of the present invention to the roughened surface.

[0083] The roughening treatment is preferably carried out in a copper sulfate solution containing, for example, a copper concentration of 7 g / L or higher and 17 g / L or lower, and a sulfuric acid concentration of 50 g / L or higher and 200 g / L or lower, at a temperature of 20°C or higher and 40°C, at a rate of 10 A / dm².2 Above and 50A / dm 2 Electrolytic extraction is then performed. This electrolytic extraction is preferably performed for 0.5 seconds or more and 30 seconds or less, more preferably for 1 second or more and 30 seconds or less, and even more preferably for 1 second or more and 3 seconds or less. Of course, the roughening treatment copper foil involved in this invention is not limited to the above method and can be manufactured by any method.

[0084] When the above electrolytic reaction occurs, the following formula applies:

[0085] R L =L / D C

[0086] (where R is in the formula) L Where L is the liquid resistance index (mm·L / mol), L is the distance between electrodes (anode-cathode) (mm), and D is the liquid resistance index (mm·L / mol). C (charge carrier density (mol / L))

[0087] The defined liquid resistance index R L Preferably, it is 9.0 mm·L / mol or higher and 20.0 mm·L / mol or lower, more preferably 11.0 mm·L / mol or higher and 17.0 mm·L / mol or lower. Therefore, by increasing R... L As the overall voltage of the system increases, the voltage during the protrusion formation reaction also increases. This affects the protrusion shape, resulting in the formation of protrusions with shapes suitable for imparting the surface profile required to the roughened copper foil of the present invention. It should be noted that the charge carrier density D... C The charge carrier density D can be calculated by summing the products of the concentrations and valences of 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 The following formula is used for calculation.

[0088] Dc = [H] + ]×1+[Cu 2+ ]×2+[SO4 2- ]×2

[0089] (where, [H] + [ ] represents the hydrogen ion concentration (mol / L) in the solution, [Cu 2+ [The concentration of copper ions in the solution is in mol / L, and [SO4] is in mol / L. 2- [This refers to the concentration of sulfate ions in the solution (mol / L)]

[0090] Regarding the liquid resistance index R L The relationship with voltage is explained as follows. First, based on Ohm's law, the following formula is derived.

[0091] V=ρ×L×I / S

[0092] (In the formula, V is voltage, ρ is resistivity, L is the distance between electrodes, I is current, and S is the cross-sectional area between electrodes).

[0093] That is, the voltage V is proportional to the resistivity ρ, the inter-electrode distance L, and the current density (=I / S). Furthermore, the resistivity ρ is proportional to the aforementioned charge carrier density D. C Inversely proportional. Therefore, with a constant current density, by increasing (proportional to the inter-electrode distance L and proportional to the charge carrier density D) C The voltage increases as the liquid resistance index (which is inversely proportional to the resistance of the solution) increases. Therefore, it can be said that the liquid resistance index is an indicator related to the resistance of the solution.

[0094] As desired, a rust-preventive treatment can also be applied to the roughened copper foil to form a rust-preventive layer. The rust-preventive treatment preferably includes a zinc plating process. The zinc plating process can be either a zinc plating process or a zinc alloy plating process, with a zinc-nickel alloy plating process being particularly preferred. The zinc-nickel alloy plating process can be a plating process containing at least Ni and Zn, and may further include other elements such as Sn, Cr, Co, and Mo. For example, by further including Mo in addition to Ni and Zn in the rust-preventive layer, the treated surface of the roughened copper foil exhibits better adhesion to the resin, chemical resistance, and heat resistance, and is less prone to etching residue. The Ni / Zn adhesion ratio in the zinc-nickel alloy plating is preferably 1.2 or more and 10 or less by mass, more preferably 2 or more and 7 or less, and even more preferably 2.7 or more and 4 or less. Furthermore, the rust-preventive treatment preferably further includes a chromate treatment, which is more preferably performed on the surface of the zinc-containing plating after the zinc plating process. This further improves rust resistance. A particularly preferred rust-preventive treatment is a combination of zinc-nickel alloy plating and subsequent chromate treatment.

[0095] As desired, roughened copper foil can also be treated with a silane coupling agent to form a silane coupling agent layer. This improves moisture resistance, chemical resistance, and adhesion to adhesives. The silane coupling agent layer is formed by applying a suitable dilution of the silane coupling agent and allowing it to dry. Examples of silane coupling agents include epoxy-functionalized silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-epoxypropoxypropyltrimethoxysilane; or amino-functionalized silane coupling agents such as 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. Functional silane coupling agents; or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane or olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane; or acryloyl-functional silane coupling agents such as 3-methacryloyloxypropyltrimethoxysilane and 3-acryloyloxypropyltrimethoxysilane; or imidazole-functional silane coupling agents such as imidazole silane; or triazine-functional silane coupling agents such as triazine silane, etc.

[0096] For the reasons stated above, the roughened copper foil preferably has a rust-preventive layer and / or a silane coupling agent layer on the roughened surface, and more preferably both a rust-preventive layer and a silane coupling agent layer. The rust-preventive layer and the silane coupling agent layer may be formed not only on the roughened surface of the roughened copper foil, but also on the side where no roughened surface is formed.

[0097] Copper-clad laminate

[0098] The roughened copper foil of the present invention is preferably used in the manufacture of copper-clad laminates for printed circuit boards. Specifically, according to a preferred embodiment of the present invention, a copper-clad laminate comprising the aforementioned roughened copper foil is provided. By using the roughened copper foil of the present invention, excellent transport characteristics and high peel strength can be achieved in the copper-clad laminate. This copper-clad laminate comprises: the roughened copper foil of the present invention, and a resin layer tightly disposed on the roughened surface of the roughened copper foil. The roughened copper foil may be disposed on one side or both sides of the resin layer. The resin layer comprises resin, preferably an insulating resin. The resin layer is preferably a prepreg and / or a resin sheet. Prepreg refers to a general term for composite materials impregnated with synthetic resins in substrates such as synthetic resin boards, glass boards, glass fabrics, glass nonwovens, and paper. Preferred examples of insulating resins include epoxy resin, cyanate ester resin, bismaleimide triazine resin (BT resin), polyphenylene ether resin, and phenolic resin. Examples of insulating resins constituting the resin sheet include epoxy resin, polyimide resin, and polyester resin. Furthermore, from the viewpoint of improving insulation, the resin layer may contain filler particles including various inorganic particles such as silica and alumina. The thickness of the resin layer is not particularly limited, but is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and even more preferably 3 μm or more and 200 μm or less. The resin layer may consist of multiple layers. The resin layer, such as prepreg and / or resin sheet, may be disposed on the roughened copper foil through a primer resin layer pre-coated to the surface of the copper foil.

[0099] Printed Circuit Board

[0100] The roughened copper foil of the present invention is preferably used in the manufacture of printed circuit boards. That is, according to a preferred embodiment of the present invention, a printed circuit board having the aforementioned roughened copper foil is provided. By using the roughened copper foil of the present invention, excellent transmission characteristics and high peel strength can be achieved in the printed circuit board. The printed circuit board according to this embodiment comprises a layer structure of a resin layer and a copper layer stacked together. The copper layer is derived from the roughened copper foil of the present invention. Furthermore, the resin layer is as described above regarding copper-clad laminates. In any case, the printed circuit board can employ a known layer structure. Specific examples of printed circuit boards include single-sided or double-sided printed circuit boards obtained by bonding the roughened copper foil of the present invention to one or both sides of a prepreg and curing it to form a laminate, followed by circuit formation; and multilayer printed circuit boards formed by multiplying these. Other specific examples include flexible printed circuit boards, COF, and TAB tapes, where the roughened copper foil of the present invention is formed on a resin film to form a circuit. Other specific examples include: resin-coated copper foil (RCC) with the above-mentioned resin layer coated on the roughened copper foil of the present invention, and after the resin layer is laminated as an insulating adhesive layer on the above-mentioned printed circuit board, the roughened copper foil is used as a wiring layer to form a circuit by a modified semi-additive process (MSAP), a subtractive process, or other methods to form a circuit; a multilayer circuit board in which the roughened copper foil is removed and a circuit is formed by a semi-additive process (SAP); and a direct build-up wafer formed by alternately laminating resin-coated copper foil and circuits on a semiconductor integrated circuit.

[0101] Example

[0102] The invention will be illustrated more specifically by the following examples.

[0103] Examples 1 to 15

[0104] The roughening treatment of the copper foil of the present invention is carried out as follows.

[0105] (1) Manufacturing of electrolytic copper foil

[0106] For Examples 1-9 and 11-15, a sulfuric acidic copper sulfate solution with the composition shown below was used as the copper electrolyte. A titanium electrode was used as the cathode, and a DSA (dimension stability anode) was used as the anode. The solution temperature was 45°C, and the current density was 55 A / dm³. 2 Electrolysis was performed to obtain electrolytic copper foil A with the thickness shown in Table 1. At this time, an electrode with a surface roughness adjusted by polishing with a #1000 polishing wheel was used as the cathode.

[0107] Composition of Sulfuric Acid Copper Sulfate Solution

[0108] - Copper concentration: 80g / L

[0109] - Sulfuric acid concentration: 300 g / L

[0110] - Gel concentration: 5mg / L

[0111] - Chlorine concentration: 30 mg / L

[0112] On the other hand, regarding Example 10, an acidic copper sulfate solution with the composition shown below was used as the copper electrolyte to obtain electrolytic copper foil B with the thickness shown in Table 1. In this case, the conditions other than the composition of the acidic copper sulfate solution were the same as those for electrolytic copper foil A.

[0113] Composition of Sulfuric Acid Copper Sulfate Solution

[0114] - Copper concentration: 80g / L

[0115] - Sulfuric acid concentration: 260 g / L

[0116] - Bis(3-sulfopropyl)disulfide concentration: 30 mg / L

[0117] - Diallyl dimethylammonium chloride polymer concentration: 50 mg / L

[0118] - Chlorine concentration: 40 mg / L

[0119] (2) Roughening treatment

[0120] In the above-mentioned electrolytic copper foils, for Examples 1-6, 10, and 12-15, the deposition surface side is roughened, and for Examples 7-9 and 11, the electrode surface side is roughened. It should be noted that the ten-point average roughness Rz of the deposition surface of the electrolytic copper foils used in Examples 1-6, 10, and 12-15, and the electrode surface of the electrolytic copper foils used in Examples 7-9 and 11, measured using a contact surface roughness meter according to JIS B0601-1994, is shown in Table 1.

[0121] For Examples 1 to 8, the roughening treatment shown below (first roughening treatment) was performed. This roughening treatment was carried out as follows: 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), each example was electrolyzed and washed with water under the conditions of liquid resistance index, current density and time shown in Table 1.

[0122] For Examples 9 to 15, the first roughening process, the second roughening process, and the third roughening process are performed in sequence as shown below.

[0123] - The first roughening treatment is carried out as follows: electrolysis and water washing are 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) under the conditions of liquid resistance index, current density and time shown in Table 1.

[0124] - The second roughening treatment is carried out as follows: electrolysis and water washing are performed in a copper electrolytic solution with the same composition as the first roughening treatment, under the conditions of liquid resistance index, current density and time shown in Table 1.

[0125] - The third roughening treatment is carried out as follows: electrolysis and water washing are 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) under the conditions of liquid resistance index, current density and time shown in Table 1.

[0126] (3) Rust prevention treatment

[0127] The roughened electrolytic copper foil was subjected to the rust prevention treatment shown in Table 1. For Examples 1-5, 7, and 8, the roughened surface of the electrolytic copper foil was treated with a pyrophosphate bath at a concentration of 100 g / L potassium pyrophosphate, 1 g / L zinc, 2 g / L nickel, and 1 g / L molybdenum, at a temperature of 40°C and a current density of 0.5 A / dm³. 2 A zinc-nickel-molybdenum rust-preventive treatment was applied. Additionally, for the unroughened surfaces of the electrolytic copper foil, a pyrophosphate bath was used, with the following settings: potassium pyrophosphate concentration 80 g / L, zinc concentration 0.2 g / L, nickel concentration 2 g / L, solution temperature 40℃, and current density 0.5 A / dm³. 2 Zinc-nickel rust prevention treatment was performed on both sides of the electrolytic copper foil. On the other hand, regarding Examples 6 and 9-15, zinc-nickel rust prevention treatment was performed on both sides of the electrolytic copper foil under the same conditions as the unroughened sides of the electrolytic copper foil in Examples 1-5, 7 and 8.

[0128] (4) Chromate treatment

[0129] Both sides of the electrolytic copper foil that have undergone the above-mentioned rust-preventive treatment are then subjected to chromate treatment to form a chromate layer on top of the rust-preventive layer. This chromate treatment is performed at a chromic acid concentration of 1 g / L, pH 11, a solution temperature of 25°C, and a current density of 1 A / dm³. 2 It is carried out under the following conditions.

[0130] (5) Silane coupling agent treatment

[0131] The copper foil subjected to the above-described chromate treatment was washed with water, and then immediately subjected to silane coupling agent treatment, allowing the silane coupling agent to be adsorbed onto the chromate layer of the roughened surface. This silane coupling agent treatment was performed by spraying a solution of the silane coupling agent using pure water as a solvent onto the roughened surface for adsorption. 3-Aminopropyltrimethoxysilane was used as the silane coupling agent in Examples 1 and 3-8, and 3-epoxypropoxypropyltrimethoxysilane was used in Examples 2 and 9-15. The concentration of the silane coupling agent was always set to 3 g / L. After the silane coupling agent adsorption, the water was finally evaporated using an electric heater to obtain a roughened copper foil of a specified thickness.

[0132] [Table 1]

[0133]

[0134] evaluate

[0135] The following evaluations are made regarding the roughened copper foil produced.

[0136] (a) Surface properties of the roughened surface

[0137] Surface roughness analysis of the roughened copper foil was performed using a laser microscope (Olympus Corporation, OLS-5000) according to ISO 25178 or JIS B0601-2013. For Spd, Vmp, Vmc, and Sdr, as shown in Table 2, the measurement magnification was set to 200x (100x objective lens magnification × 2x optical zoom). For Rdc, Sk, and Sxp, as shown in Table 3, the measurement magnification was set to 20x (20x objective lens magnification). Other specific measurement conditions are shown in Tables 2 and 3. The surface profile of the obtained roughened surface was analyzed according to the conditions shown in Tables 2 and 3, and Spd, Vmp, Vmc, Sdr, Rdc, Sk, and Sxp were calculated. In addition, based on the obtained values ​​of Spd, Vmp, and Vmc, Vmp+Vmc and the volume of the tiny tip particle (=(Vmp+Vmc) / Spd) were calculated. The results are shown in Table 4.

[0138] [Table 2]

[0139] Table 2

[0140]

[0141] [Table 3]

[0142] Table 3

[0143]

[0144] (b) Peel strength between copper foil and substrate

[0145] For roughened copper foil under normal temperature and high humidity conditions, in order to evaluate its adhesion to the insulating substrate, the normal peel strength and wet peel strength were measured as follows.

[0146] (b-1) Normal peel strength

[0147] Two prepregs (100 μm thick) mainly composed of polyphenylene ether, triallyl isocyanurate, and bismaleimide resin were prepared and stacked as the insulating substrate. A surface-treated copper foil was then layered onto the prepreg with its roughened surface in contact with the prepreg, and subjected to a 32 kgf / cm² pressure. 2 A copper-clad laminate was manufactured by pressing at 205°C for 120 minutes. Next, circuitry was formed on the copper-clad laminate using etching to create a test substrate with a linear circuit 3 mm wide. It should be noted that for Examples 1, 2, and 12, copper plating was performed on the copper foil side surface of the copper-clad laminate until the copper foil thickness reached 18 μm before circuitry formation. Furthermore, for Examples 4-6, 14, and 15, the copper foil side surface of the copper-clad laminate was etched until the copper foil thickness reached 18 μm before circuitry formation. The obtained linear circuit was peeled from the insulating substrate using Method A (90° peel) according to JIS C 5016-1994, and the normal peel strength (kgf / cm) was measured. The quality of the obtained normal peel strength was evaluated based on the following criteria. The results are shown in Table 4.

[0148] <Standardized Peel Strength Evaluation Criteria>

[0149] -Good: Normal peel strength is above 0.40 kgf / cm

[0150] -Poor: Normal peel strength less than 0.40 kgf / cm

[0151] (b-2) Wet peel strength

[0152] Except that the test substrate with linear circuitry was immersed in boiling water for 2 hours before the peel strength measurement, the wet peel strength (kgf / cm) was measured using the same procedure as the normal peel strength measurement. The quality of the obtained wet peel strength was evaluated based on the following criteria. The results are shown in Table 4.

[0153] <Evaluation Criteria for Moisture Peel Strength>

[0154] -Good: Wet peel strength is above 0.40 kgf / cm

[0155] -Poor: Wet peel strength less than 0.40 kgf / cm

[0156] (c) Transmission characteristics

[0157] A high-frequency substrate (Panasonic, MEGTRON 6N) was prepared as the insulating resin substrate. Roughened copper foil was laminated onto both sides of the insulating resin substrate with its roughened surface in contact with the substrate. The lamination was performed using a vacuum press at 190°C for 120 minutes to obtain a copper-clad laminate with an insulation thickness of 136 μm. The laminate was then etched to obtain a substrate for measuring transmission loss of microstrip lines with a characteristic impedance of 50 Ω. The transmission loss (dB / cm) at 28 GHz was measured on the obtained substrate using a network analyzer (Keysight Technologies, N5225B). The quality of the obtained transmission loss was evaluated based on the following benchmarks. The results are shown in Table 4.

[0158] <Transmission Loss Evaluation Criteria>

[0159] -Good: Transmission loss is above -0.33dB / cm

[0160] -Poor: Transmission loss less than -0.33dB / cm

[0161] [Table 4]

[0162]

Claims

1. A roughened copper foil having a roughened surface on at least one side, The volume of the tiny tip particles on the roughened surface, calculated using the formula (Vmp + Vmc) / Spd, is 1.300 μm, based on the solid volume of the protruding peaks per unit area, Vmc of the center per unit area, and the peak density Spd per unit area. 3 For items with a cross-sectional height difference Rdc of 0.95 μm or more, the units of Vmp and Vmc are μm. 3 / μm 2 The unit of Spd is units per μm. 2 , The values ​​of Vmp, Vmc, and Spd were measured according to ISO 25178 under the conditions of a magnification of 200x, a cutoff wavelength of 0.3μm based on an S-filter, and a cutoff wavelength of 5μm based on an L-filter. The Rdc is a value obtained from the roughness curve measured according to JIS B0601-2013 under the conditions of a magnification of 20 times, no cutoff based on the cutoff value λs, and a cutoff wavelength of 320 μm based on the cutoff value λc. The Rdc is the difference of the cross-sectional height c in the height direction at Rmr1 and Rmr2, in the form of c(Rmr1) - c(Rmr2). Rmr1 specifies a load length ratio of 20%, and Rmr2 specifies a load length ratio of 80%.

2. The roughened copper foil according to claim 1, wherein, The cross-sectional height difference Rdc of the roughened surface is greater than 1.10 μm and less than 20.00 μm.

3. The roughened copper foil according to claim 1 or 2, wherein, The solid volume Vmc of the central portion per unit area of ​​the roughened surface is 0.360 μm. 3 / μm 2 the following.

4. The roughened copper foil according to claim 1 or 2, wherein, The sum of the solid volume Vmp of the protruding peak and the solid volume Vmc of the center of the roughened surface, i.e., Vmp + Vmc, is 0.380 μm. 3 / μm 2 the following.

5. The roughened copper foil according to claim 1 or 2, wherein, The interface expansion area ratio Sdr of the roughened surface is less than 70%, and Sdr is a value measured according to ISO25178 under the conditions of magnification of 200 times, cutoff wavelength of 0.3 μm based on S filter and cutoff wavelength of 5 μm based on L filter.

6. The roughened copper foil according to claim 1 or 2, wherein, The horizontal difference Sk at the center of the roughened surface is 1.50 μm or more. Sk is a value measured according to ISO25178 at a magnification of 20x, without S-filter cutoff and with L-filter cutoff wavelength of 320 μm.

7. The roughened copper foil according to claim 1 or 2, wherein, The pole height Sxp of the roughened surface is 1.10 μm or more, and Sxp is a value measured according to ISO25178 under the conditions of magnification of 20 times, without S-based cutoff and L-based cutoff wavelength of 320 μm.

8. The roughened copper foil according to claim 1 or 2, wherein, The peak density Spd per unit area of ​​the roughened surface is 0.12 peaks / μm. 2 Above and 0.46 per μm 2 the following.

9. The roughened copper foil according to claim 1 or 2, wherein the roughened surface further comprises a rust-preventive treatment layer and / or a silane coupling agent treatment layer.

10. The roughened copper foil according to claim 1 or 2, wherein, The roughened copper foil is an electrolytic copper foil, and the roughened surface exists on the deposition surface side of the electrolytic copper foil.

11. A copper-clad laminate comprising the roughened copper foil as described in claim 1 or 2.

12. A printed circuit board comprising the roughened copper foil as described in claim 1 or 2.

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