JP7374298B2 - Roughened copper foil, copper clad laminates and printed wiring boards - Google Patents

Description

The present invention relates to a roughened copper foil, a copper-clad laminate, and a printed wiring board.

In the manufacturing process of printed wiring boards, copper foil is widely used in the form of a copper-clad laminate laminated with an insulating resin base material. In this regard, it is desirable that the copper foil and the insulating resin base material have high adhesion in order to prevent the wiring from peeling off during the manufacture of the printed wiring board. Therefore, in conventional copper foil for manufacturing printed wiring boards, the bonding surface of the copper foil is roughened to form irregularities made of fine copper particles, and these irregularities are pressed into the inside of the insulating resin base material. This improves adhesion by creating an anchor effect.

As a copper foil that has been subjected to such a roughening treatment, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2018-172785) describes a copper foil and a surface treatment having a roughening treatment layer on at least one surface of the copper foil. The copper foil has a skewness Ssk of -0.6 or more and -0.35 or less on the surface on the roughening treatment layer side, and a glossiness in TD (width direction) of the surface on the roughening treatment layer side is 70% or less. something is disclosed. According to such surface-treated copper foil, it is said that the falling off of the roughened particles provided on the surface of the copper foil is well suppressed, and the occurrence of wrinkles and streaks when bonded to an insulating substrate is well suppressed. ing. Furthermore, Patent Document 1 also discloses a surface-treated copper foil in which the height Spk of the protruding peaks on the surface of the roughened layer side is 0.13 μm or more and 0.27 μm or less, for the purpose of obtaining the above effects. .

By the way, with the increasing functionality of portable electronic devices in recent years, the frequency of signals, whether digital or analog, is increasing in order to process large amounts of data at high speed, and printed wiring boards suitable for high frequency applications are It has been demanded. Such a high frequency printed wiring board is desired to reduce transmission loss in order to be able to transmit high frequency signals without deteriorating them. Printed wiring boards are equipped with copper foil processed into a wiring pattern and an insulating base material, but the main transmission losses are conductor loss due to the copper foil and dielectric loss due to the insulating base material. This includes losses.

In this regard, a roughened copper foil has been proposed to reduce transmission loss. For example, Patent Document 2 (Japanese Unexamined Patent Publication No. 2015-148011) discloses that the surface of the copper foil is improved by surface treatment, with the aim of providing a surface-treated copper foil with low signal transmission loss and a laminate using the same. It is disclosed 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.

Japanese Patent Application Publication No. 2018-172785 Japanese Patent Application Publication No. 2015-148011

As mentioned above, in recent years, there has been a demand for improved transmission characteristics (high frequency characteristics) of printed wiring boards. In order to meet these demands, attempts have been made to perform finer roughening treatment on the bonding surface of copper foil with the insulating resin base material. In other words, in order to reduce the unevenness of the copper foil surface that increases transmission loss, a fine roughening treatment is performed on the copper foil surface with small waviness (for example, the surface of double-sided smooth foil or the electrode surface of electrolytic copper foil). It is possible that However, when processing copper-clad laminates or manufacturing printed wiring boards using such roughened copper foil, the problem is that the peel strength between the copper foil and the base material is generally low and the adhesion reliability is poor. may occur.

The present inventors have recently determined, on the surface of a roughened copper foil, the ratio (Spk/Ssk or S10z/Ssk) and the ten-point average height S10z under conditions that reflect the waviness component of the copper foil, respectively, are controlled within predetermined ranges, so that in a copper-clad laminate or printed wiring board manufactured using the same, We have found that it is possible to achieve both excellent transmission characteristics and high peel strength.

Therefore, an object of the present invention is to provide a roughened copper foil that can have both excellent transmission characteristics and high peel strength when used in copper-clad laminates or printed wiring boards.

According to one aspect of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side,
The roughened surface has a cutoff wavelength of S filter according to ISO 25178 with respect to skewness Ssk measured under conditions of a cutoff wavelength of 0.3 μm with S filter and 5 μm with L filter according to ISO 25178. The microparticle tip diameter index Spk/Ssk, which is the ratio of the protruding peak height Spk (μm) measured under the conditions of 0.3 μm and a cutoff wavelength of 5 μm using an L filter, is 0.20 or more and 1.00 or less, And, the roughened copper foil has a ten-point average height S10z of 2.50 μm or more measured under the conditions of a cutoff wavelength of 0.3 μm with an S filter and a cutoff wavelength of 64 μm with an L filter in accordance with ISO25178. provided.

According to another aspect of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side,
The roughened surface has a cutoff wavelength of S filter according to ISO 25178 with respect to skewness Ssk measured under conditions of a cutoff wavelength of 0.3 μm with S filter and 5 μm with L filter according to ISO 25178. The microparticle tip roughness index S10z/Ssk, which is the ratio of the ten-point average height S10z (μm) measured under the conditions of 0.3 μm and a cutoff wavelength of 5 μm using an L filter, is 1.00 or more and 6.00 or less. , and a roughened copper foil having a ten-point average height S10z of 2.50 μm or more measured under the conditions of a cutoff wavelength of 0.3 μm by an S filter and a cutoff wavelength of 64 μm by an L filter in accordance with ISO 25178. is provided.

According to yet another aspect of the present invention, there is provided a copper-clad laminate including the roughened copper foil.

According to yet another aspect of the present invention, there is provided a printed wiring board including the roughened copper foil.

FIG. 3 is a diagram for explaining the skewness Ssk determined in accordance with ISO25178, and is a diagram showing the surface and its height distribution when Ssk<0. FIG. 3 is a diagram for explaining skewness Ssk determined in accordance with ISO25178, and is a diagram showing a surface and its height distribution when Ssk>0. It is a figure for explaining the load curve and load area ratio determined based on ISO25178. It is a figure for explaining the load area ratio Smr1 which separates a protruding peak part and a core part, and load area ratio Smr2 which separates a protruding valley part and a core part, and are determined based on ISO25178. It is a figure for explaining the pole height Sxp determined based on ISO25178. FIG. 3 is a diagram for explaining that the surface unevenness of the roughened copper foil is composed of a roughened particle component and a waviness component. FIG. 1 is a schematic diagram showing an example of a roughened copper foil of the present invention.

Definitions Definitions of terms and parameters used to specify the present invention are shown below.

In this specification, "skewness Ssk" is a parameter representing the symmetry of height distribution, which is measured in accordance with ISO25178. When this value is 0, it indicates that the height distribution is vertically symmetrical. Moreover, as shown in FIG. 1A, when this value is smaller than 0, it indicates that the surface has many fine valleys. On the other hand, as shown in FIG. 1B, if this value is greater than 0, it indicates a surface with many fine peaks.

In this specification, the term "surface load curve" (hereinafter simply referred to as "load curve") refers to a curve representing the height at which the load area ratio is from 0% to 100%, which is measured in accordance with ISO25178. say. As shown in FIG. 2, the load area ratio is a parameter representing the area of a region having a certain height c or more. The load area ratio at height c corresponds to Smr(c) in FIG. As shown in Figure 3, the secant line of a load curve drawn from a load area ratio of 0% along the load curve with a difference in load area ratio of 40% is moved from the load area ratio of 0%, and the secant line The position where the slope is the gentlest is called the center of the load curve. The straight line that minimizes the sum of squares of deviations in the vertical axis direction with respect to this central portion is called an equivalent straight line. The portion included in the height range of 0% to 100% of the load area ratio of the equivalent straight line is called the core portion. The portion higher than the core portion is called a protruding peak portion, and the portion lower than the core portion is called a protruding trough portion.

In this specification, the "protruding peak height Spk" refers to the average height of the protruding peaks above the core portion, as measured in accordance with ISO25178.

In this specification, "pole height Sxp" is a parameter representing the difference in height between the load area ratio p% and the load area ratio q%, which is measured in accordance with ISO25178, as shown in FIG. be. Sxp represents the difference between the average surface of the surface and the height of the surface after removing particularly high peaks on the surface. In this specification, Sxp is the difference in height between a load area ratio of 2.5% and a load area ratio of 50%.

In this specification, the "ten-point average height S10z" refers to the average height of the fifth highest mountain peak and the average depth of the fifth deepest valley among the mountain peaks and valley bottoms within the reference area. It refers to the sum of positive values.

In this specification, "interface developed area ratio Sdr" refers to the percentage increase of the developed area (surface area) of the defined region relative to the area of the defined region, as measured in accordance with ISO25178. It is a parameter expressed as . The smaller this value is, the more flat the surface shape is, and the Sdr of a completely flat surface is 0%. On the other hand, the larger this value is, the more uneven the surface shape is.

In this specification, the "microparticle tip diameter index Spk/Ssk" is the ratio of the protruding peak height Spk (μm) to the skewness Ssk. Furthermore, in this specification, "microparticle tip roughness index S10z/Ssk" is the ratio of ten-point average height S10z (μm) to skewness Ssk.

The skewness Ssk, the protruding peak height Spk, the pole height Sxp, the ten-point average height S10z, and the developed area ratio Sdr of the interface are calculated based on a predetermined measurement area (for example, 129.419 μm x 128.704 μm square) on the roughened surface. Each can be calculated by measuring the surface profile of the dimensional area) using a commercially available laser microscope.

In this specification, the skewness Ssk, the protruding peak height Spk, and the pole height Sxp are measured under conditions of a cutoff wavelength of 0.3 μm for the S filter and a cutoff wavelength of 5 μm for the L filter. Further, in this specification, the developed area ratio Sdr of the interface is measured under the conditions of a cutoff wavelength of 0.3 μm for the S filter and a cutoff wavelength of 64 μm for the L filter. Furthermore, in this specification, when the ten-point average height S10z is used to calculate the fine particle tip roughness S10z/Ssk, the cutoff wavelength of the S filter is 0.3 μm and the cutoff wavelength of the L filter is 5 μm. (Hereinafter, the ten-point average height S10z measured under these conditions may be referred to as the "ten-point average height S10z (roughened particles S10z)" as necessary). On the other hand, in cases other than when used to calculate the fine particle tip roughness S10z/Ssk, the ten-point average height S10z is measured under the conditions of a cutoff wavelength of 0.3 μm with an S filter and a cutoff wavelength of 64 μm with an L filter. (Hereinafter, the ten-point average height S10z measured under these conditions may be referred to as the "ten-point average height S10z (overall S10z)" as necessary).

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

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

Roughening treated copper foil The copper foil of the present invention is a roughening treated copper foil. This roughened copper foil has a roughened surface on at least one side. The roughened surface has a microparticle tip diameter index Spk/Ssk, which is the ratio of the protruding peak height Spk (μm) to the skewness Ssk, of 0.20 or more and 1.00 or less, and a ten-point average height S10z (overall S10z) is 2.50 μm or more, and/or the microparticle tip roughness index S10z/Ssk, which is the ratio of the ten-point average height S10z (roughened particles S10z) (μm) to the skewness Ssk, is 1.00. 6.00 or less, and the ten-point average height S10z (overall S10z) is 2.50 μm or more. In this way, in the roughening-treated copper foil, Spk/Ssk or S10z/Ssk under the condition where the waviness component of the copper foil is cut, and S10z under the condition where the waviness component of the copper foil is reflected, are each controlled within a predetermined range. Therefore, in a copper-clad laminate or printed wiring board manufactured using the same, it is possible to achieve both excellent transmission characteristics (high frequency characteristics) and high peel strength (for example, normal peel strength and peel strength after heat load). .

It is inherently difficult to achieve both excellent transmission characteristics and high peel strength. This is because in order to obtain excellent transmission characteristics, it is necessary to reduce the unevenness on the copper foil surface, while in order to obtain high peel strength, it is necessary to increase the unevenness on the copper foil surface. This is because there is a trade-off relationship. Here, as shown in FIG. 5, the unevenness on the surface of the roughened copper foil consists of a "roughening particle component" and a "waviness component" having a longer period than the roughening particle component. Generally, in order to obtain excellent transmission characteristics, fine roughening treatment is performed on the copper foil surface with small waviness (for example, the surface of double-sided smooth foil or the electrode surface of electrolytic copper foil) to remove small roughening particles. However, when a copper-clad laminate or printed wiring board is manufactured using such a roughened copper foil, the peel strength between the copper foil and the base material generally becomes low.

In response to this problem, the present inventors investigated the effects of roughening particles and waviness on the surface of the copper foil on transmission characteristics and peel strength. As a result, it was found that the waviness component of the copper foil had little effect on the transmission characteristics, contrary to expectations, and that the size of the roughening particles mainly affected the transmission characteristics. Then, the present inventors perform evaluation by combining the skewness Ssk and the protruding peak height Spk under conditions where the waviness component of the copper foil is cut, or the skewness Ssk and the ten-point average height S10z (roughening particles S10z). We found that this makes it possible to accurately evaluate the tip diameter or tip roughness of microparticles (roughening particles) that affect transmission characteristics. Specifically, excellent transmission characteristics are achieved by setting the fine particle tip diameter index Spk/Ssk or the fine particle tip roughness index S10z/Ssk on the roughened surface of the roughened copper foil within the above range. I found out what I can do. Furthermore, by setting the ten-point average height S10z (total S10z) under conditions that reflect the waviness component of the copper foil within the above range, even small roughening particles that are originally difficult to secure peel strength, We have also discovered that high peel strength between the copper foil and the substrate can be achieved by utilizing the waviness of the copper foil. As described above, the roughened copper foil of the present invention can achieve both excellent transmission characteristics and high peel strength when used in copper-clad laminates or printed wiring boards.

The roughened particle component and the waviness component on the surface of the copper foil can be distinguished by using an S filter and an L filter of a laser microscope. Specifically, by measuring the roughened surface of the roughened copper foil under the conditions of a cutoff wavelength of 0.3 μm using an S filter and a cutoff wavelength of 5 μm using an L filter, we measured the roughness with the effect of waviness removed. parameters of the particle components can be obtained. Therefore, in the present invention, the skewness Ssk, the protruding peak height Spk, the pole height Sxp, the ten-point average height S10z (roughened particles S10z), the fine particle tip diameter index Spk/Ssk, and the fine particle tip roughness index S10z It can be said that /Ssk accurately reflects the parameters of the roughening particles on the surface of the copper foil. In contrast, by measuring the copper foil surface under the conditions of a cutoff wavelength of 0.3 μm using an S filter and a cutoff wavelength of 64 μm using an L filter, we found that the overall surface reflected the effects of both the roughening particle component and the waviness component. parameters can be obtained. Therefore, it can be said that the developed area ratio Sdr and the ten-point average height S10z (overall S10z) of the interface in the present invention are parameters that reflect not only the roughening particle component on the copper foil surface but also the waviness component.

According to one aspect of the present invention, the roughened copper foil has a fine particle tip diameter index Spk/Ssk on the roughened surface of 0.20 μm or more and 1.00 μm or less, preferably 0.30 μm or more and 0.90 μm. The thickness is more preferably 0.40 μm or more and 0.80 μm or less, particularly preferably 0.50 μm or more and 0.75 μm or less. Further, the roughened surface of the roughened copper foil preferably has a skewness Ssk of 0.40 or more and 1.20 or less, more preferably 0.45 or more and 1.17 or less, and even more preferably 0.50 or more. It is 1.14 or less, particularly preferably 0.55 μm or more and 1.10 μm or less. Further, the roughened surface of the roughened copper foil preferably has a protruding peak height Spk of 0.25 μm or more and 0.80 μm or less, more preferably 0.40 μm or more and 0.80 μm or less, and even more preferably It is 0.40 μm or more and 0.78 μm or less, particularly preferably 0.42 μm or more and 0.76 μm or less. As mentioned above, the skewness Ssk, the protruding peak height Spk, and the microparticle tip diameter index Spk/Ssk in the present invention are free from the influence of the waviness component of the unevenness on the copper foil surface, and therefore have no effect on the transmission characteristics. It becomes possible to accurately measure the diameter of the microscopic tip of the roughening particles that have an effect. In this regard, when the skewness Ssk, the protruding peak height Spk, and/or the microparticle tip diameter index Spk/Ssk are within the above ranges, it is possible to achieve better transmission characteristics while maintaining high peel strength. .

According to another aspect of the present invention, the roughened copper foil has a fine particle tip roughness index S10z/Ssk on the roughened surface of 1.00 μm or more and 6.00 μm or less, preferably 1.50 μm or more. It is 6.00 μm or less, more preferably 2.00 μm or more and 6.00 μm or less, particularly preferably 2.00 μm or more and 5.50 μm or less. Further, the roughened surface of the roughened copper foil preferably has a skewness Ssk of 0.40 or more and 1.20 or less, more preferably 0.45 or more and 1.17 or less, and even more preferably 0.50 or more. It is 1.14 or less, particularly preferably 0.55 μm or more and 1.10 μm or less. Further, the roughened surface of the roughened copper foil preferably has a ten-point average height S10z (roughened particles S10z) of 1.50 μm or more and 4.00 μm or less, more preferably 2.00 μm or more and 4.0 μm or more. 00 μm or less, more preferably 2.20 μm or more and 3.80 μm or less, particularly preferably 2.30 μm or more and 3.60 μm or less, and most preferably 2.40 μm or more and 3.40 μm or less. As mentioned above, the skewness Ssk, ten-point average height S10z (roughening particles S10z), and microparticle tip roughness index S10z/Ssk in the present invention are obtained by cutting the influence of the waviness component of the unevenness on the copper foil surface. , Therefore, it becomes possible to measure an accurate value of the micro-tip roughness of the roughening particles, which affects the transmission characteristics. In this regard, if the skewness Ssk, ten-point average height S10z (roughening particles S10z), and/or microparticle tip roughness index S10z/Ssk are within the above ranges, superior transmission can be achieved while maintaining high peel strength. characteristics can be realized.

The roughened surface of the roughened copper foil has a ten-point average height S10z (overall S10z) of 2.50 μm or more, preferably 2.50 μm or more and 10.00 μm or less, more preferably 2.90 μm or more.9. 00 μm or less, more preferably 3.30 μm or more and 8.00 μm or less, particularly preferably 3.70 μm or more and 7.00 μm or less. The ten-point average height S10z (overall S10z) reflects the undulation component of the unevenness on the copper foil surface, and as described above, if the ten-point average height S10z (overall S10z) is within the above range, While having excellent transmission characteristics, it is possible to achieve high peel strength between the copper foil and the substrate by utilizing the waviness of the copper foil.

The roughened surface of the roughened copper foil preferably has an interface developed area ratio Sdr of 22.00% or more, more preferably 25.00% or more, still more preferably 30.00%, and even more preferably is 34.00% or more and 130.00% or less, particularly preferably 37.00% or more and 100.00% or less, and most preferably 40.00% or more and 60.00% or less. When the developed area ratio Sdr of the interface is within the above range, the roughened surface has a shape rich in irregularities that is convenient for realizing higher peel strength, while having excellent dielectric properties.

The roughened surface of the roughened copper foil preferably has a pole height Sxp of 0.40 μm or more and 1.60 μm or less, more preferably 0.50 μm or more and 1.60 μm or less, and even more preferably 0.60 μm or more. It is 1.60 μm or less, even more preferably 0.60 μm or more and 1.30 μm or less, particularly preferably 0.60 μm or more and 1.20 μm or less, and most preferably 0.60 μm or more and 1.10 μm or less. The pole height Sxp is the difference between the average plane of the surface and the height of the peaks of the surface, and if the pole height Sxp is within the above range, the anchor effect will be effectively exhibited and higher peel strength will be achieved. It can be realized.

The thickness of the roughened copper foil is not particularly limited, but is preferably 0.1 μm or more and 35 μm or less, more preferably 0.5 μm or more and 18 μm or less. Note that the roughened copper foil of the present invention is not limited to the one in which the surface of ordinary copper foil is roughened, but also the surface of copper foil with a carrier subjected to roughening treatment or fine roughening treatment. It may be something.

An example of the roughened copper foil of the present invention is shown in FIG. As shown in FIG. 6, the roughened copper foil of the present invention is a copper foil surface having a predetermined undulation (for example, the deposition surface of an electrolytic copper foil), which is roughened under desired low roughening conditions. It can be preferably manufactured by forming 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 side opposite to the electrode surface of the electrolytic copper foil (ie, on the deposition surface side). Note that the roughened copper foil may have a roughened surface on both sides, or may have a roughened surface only on one side. The roughened surface typically includes a plurality of roughened particles, and each of the plurality of roughened particles is preferably made of copper particles. The copper particles may be made of metallic copper or may be made of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably performed by forming roughening particles of copper or copper alloy on the copper foil. The copper foil before being subjected to the roughening treatment may be a non-roughened copper foil or may be a copper foil subjected to preliminary roughening. The surface of the copper foil to be subjected to the roughening treatment preferably has a ten-point average roughness Rz of 1.50 μm or more and 10.00 μm or less, more preferably It is 2.00 μm or more and 8.00 μm or less. Within the above range, it becomes easy to provide the roughened surface with the surface profile required for the roughened copper foil of the present invention.

The roughening treatment is performed at a temperature of 20° C. or higher and 40° C. or higher at 20 A/dm or higher and 50 A or higher in a copper sulfate solution containing, for example, a copper concentration of 5 g/L or more and 20 g/L or less and a sulfuric acid concentration of 50 g/L or more and 200 g/L ^or less. It is preferable to carry out electrolytic deposition at a temperature of /dm ² or less. This electrolytic deposition is preferably performed for 0.5 seconds or more and 30 seconds or less, more preferably 1 second or more and 30 seconds or less, and even more preferably 1 second or more and 3 seconds or less. As another example, when adding 9-phenylacridine (9PA), it contains copper and sulfuric acid at the above concentrations, and the chlorine concentration is 20 mg/L or more and 100 mg/L or less, and 9PA is 100 mg/L or more and 200 mg/L. It is preferable to perform electrolytic deposition at a temperature of 20° C. or higher and 40° C. or lower and 20 A/dm ² or higher and 200 A/dm ^{2 or} lower in a copper sulfate solution containing the following. This electrolytic deposition is preferably performed for 0.3 seconds or more and 30 seconds or less, more preferably 0.5 seconds or more and 1.0 seconds or less. During electrolytic deposition, the following formula:
F _Cu =F _CuSo4 ×C _Cu /S
(In the formula, F _Cu is the interelectrode copper supply amount [(g・m)/(min・L)], F _CuSo4 is the flow rate of the copper sulfate solution (m ³ /min), and C _Cu is the copper concentration of the copper sulfate solution. (g/L), S is the cross-sectional area (m ² ) between the anode and cathode)
It is preferable that the inter-electrode copper supply amount defined by 0.1 [(g·m)/(min·L)] or more and 1.0 [(g·m)/(min·L)] or less be set. By doing so, it becomes easier to provide the surface of the roughened copper foil with the surface profile required for the roughened copper foil of the present invention. However, the roughened copper foil according to the present invention is not limited to the above method, and may be manufactured by any method.

If desired, the roughened copper foil may be subjected to rust prevention treatment and may have a rust prevention treatment layer formed thereon. Preferably, the rust prevention treatment includes plating treatment using zinc. The plating treatment using zinc may be either a zinc plating treatment or a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment that contains at least Ni and Zn, and may further contain other elements such as Sn, Cr, Co, and Mo. For example, by further including Mo in addition to Ni and Zn, the rust-preventing treatment layer provides the treated surface of the roughened copper foil with excellent adhesion to resin, chemical resistance, and heat resistance, and also has less etching residue. It will be difficult to leave behind. The Ni/Zn adhesion ratio in zinc-nickel alloy plating is preferably 1.2 or more and 10 or less, more preferably 2 or more and 7 or less, and even more preferably 2.7 or more and 4 or less, in terms of mass ratio. Moreover, it is preferable that the rust prevention treatment further includes chromate treatment, and it is more preferable that this chromate treatment is performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust prevention properties can be further improved. A particularly preferred anticorrosion treatment is a combination of zinc-nickel alloy plating treatment followed by 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 layer. This makes it possible to improve moisture resistance, chemical resistance, adhesion to adhesives, and the like. The silane coupling agent layer can be formed by appropriately diluting a silane coupling agent, applying 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. a functional silane coupling agent, or a mercapto-functional silane coupling agent, such as 3-mercaptopropyltrimethoxysilane, or an olefin-functional silane coupling agent, such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacryloxy Acrylic functional silane coupling agents such as propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, imidazole functional silane coupling agents such as imidazole silane, or triazine functional silane coupling agents such as triazine silane, etc. Can be mentioned.

For the reasons mentioned above, it is preferable that the roughened copper foil further includes a rust prevention treatment layer and/or a silane coupling agent layer on the roughening treatment surface, and more preferably, a rust prevention treatment layer and/or a silane coupling agent layer. Have both. The rust prevention layer and the silane coupling agent 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 embodiment of the present invention, a copper-clad laminate including the roughened copper foil is provided. By using the roughened copper foil of the present invention, it is possible to achieve both excellent dielectric properties and high peel strength in a copper-clad laminate. This copper-clad laminate includes 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 or both sides of the resin layer. The resin layer contains a resin, preferably an insulating resin. Preferably, the resin layer is a prepreg and/or a resin sheet. Prepreg is a general term for composite materials in which a base material such as a synthetic resin plate, glass plate, glass woven fabric, glass nonwoven fabric, or paper is impregnated with synthetic resin. Preferred examples of the insulating resin include epoxy resin, cyanate resin, bismaleimide triazine resin (BT resin), polyphenylene ether resin, and phenol resin. Furthermore, examples of the insulating resin constituting the resin sheet include insulating resins such as epoxy resin, polyimide resin, and polyester resin. Further, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation properties. 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 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 via a primer resin layer that is previously 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 embodiment of the present invention, a printed wiring board including the roughened copper foil is provided. 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 embodiment includes a layered 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. Further, the resin layer is as described above regarding the copper-clad laminate. In any case, a known layer structure can be used for the printed wiring board. Specific examples of printed wiring boards include single-sided or double-sided printed wiring boards in which the roughened copper foil of the present invention is adhered to one or both sides of prepreg to form a cured laminate, and circuits are formed on the cured laminate, and multilayered versions of these. Examples include multilayer printed wiring boards. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc. in which a circuit is formed by forming the roughened copper foil of the present invention on a resin film. As another specific example, a resin-coated copper foil (RCC) is formed by applying the above-mentioned resin layer to the roughened copper foil of the present invention, and the resin layer is laminated on the above-mentioned printed circuit board as an insulating adhesive layer. After that, build-up wiring boards with circuits formed using methods such as the modified semi-additive (MSAP) method and subtractive method using the roughened copper foil as all or part of the wiring layer, and the roughened copper foil are removed. Examples include a build-up wiring board in which a circuit is formed using a semi-additive (SAP) method, and a direct build-up on wafer in which lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit.

The present invention will be further illustrated by the following examples.

Examples 1 to 18
The roughened copper foil of the present invention was manufactured as follows.

(1) Production of electrolytic copper foil For Examples 1 to 9 and 11 to 18, 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 DSA ( Using a dimensionally stable anode), electrolysis was carried out at a solution temperature of 45° C. and a current density of 55 A/dm ² to obtain electrolytic copper foil A having the thickness shown in Table 1. At this time, an electrode whose surface was polished with a #1000 buff to adjust the surface roughness was used as the cathode.
<Composition of sulfuric acid acidic copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 300g/L
- Glue concentration: 5mg/L
- Chlorine concentration: 30mg/L

On the other hand, for Example 10, an electrolytic copper foil B having the thickness shown in Table 1 was obtained using a sulfuric acid acidic copper sulfate solution having the composition shown below as the copper electrolyte. At this time, the conditions other than the composition of the sulfuric acid copper sulfate solution were the same as those for electrolytic copper foil A.
<Composition of sulfuric acid acidic copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 260g/L
- Bis(3-sulfopropyl) disulfide concentration: 30mg/L
- Diallyldimethylammonium chloride polymer concentration: 50mg/L
- Chlorine concentration: 40mg/L

(2) Roughening treatment Of the electrode surface and deposition surface of the electrolytic copper foil described above, for Examples 1 to 11 and 15 to 18, the deposition surface side is treated, and for Examples 12 to 14, the electrode surface side is , roughening treatment was performed. In addition, the ten-point average of the deposition surface of the electrolytic copper foil used in Examples 1 to 11 and 15 to 18, and the electrode surface of the electrolytic copper foil used in Examples 12 to 14, measured in accordance with JIS B0601-1994. The roughness Rz was as shown in Table 1.

For Examples 1 to 9 and 14 to 17, the following roughening treatment (first roughening treatment) was performed. This roughening treatment is carried out in each case in a copper electrolytic solution for roughening treatment (copper concentration: 5 g/L or more and 20 g/L or less, sulfuric acid concentration: 50 g/L or more and 200 g/L or less, liquid temperature: 30°C). Electrolysis was carried out under the conditions of current density, time, and interelectrode copper supply amount shown in Table 1, followed by washing with water.

For Examples 10 to 13, the following first roughening treatment, second roughening treatment, and third roughening treatment were performed in this order.
- The first roughening treatment was carried out using Table 1 in a copper electrolytic solution for roughening treatment (copper concentration: 5 g/L or more and 20 g/L or less, sulfuric acid concentration: 50 g/L or more and 200 g/L or less, liquid temperature: 30°C). Electrolysis was carried out under the conditions of the current density, time, and interelectrode copper supply amount shown in , followed by washing with water.
- The second roughening treatment is performed by electrolyzing in a copper electrolytic solution for roughening treatment with the same composition as the first roughening treatment under the conditions of current density, time, and interelectrode copper supply amount shown in Table 1, and washing with water. I went there.
- The third roughening treatment was carried out 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.) according to Table 1. Electrolysis was carried out under the conditions of the current density, time, and interelectrode copper supply amount shown in , followed by washing with water.

For Example 18, the roughening treatment (first roughening treatment) shown below was performed. This roughening treatment is carried out using a copper electrolytic solution for roughening treatment (copper concentration: 5 g/L or more and 20 g/L or less, sulfuric acid concentration: 50 g/L or more and 200 g/L or less, chlorine concentration 20 mg/L or more and 100 mg/L or less, 9PA 100 mg). /L or more and 200 mg/L or less, liquid temperature: 30° C.) under the conditions of the current density, time, and interelectrode copper supply amount shown in Table 1, followed by washing with water.

(3) Rust prevention treatment The rust prevention treatment shown in Table 1 was performed on the electrolytic copper foil after the roughening treatment. In Examples 1 to 7 and 9 to 18, a pyrophosphate bath was used for both sides of the electrolytic copper foil as the rust prevention treatment, with a potassium pyrophosphate concentration of 80 g/L, a zinc concentration of 0.2 g/L, and a nickel concentration of 2 g. /L, a liquid temperature of 40° C., and a current density of 0.5 A/dm ² to perform zinc-nickel rust prevention treatment. On the other hand, for Example 8, on the roughened side of the electrolytic copper foil, potassium pyrophosphate concentration 100 g/L, zinc concentration 1 g/L, nickel concentration 2 g/L, molybdenum concentration 1 g/L, liquid Zinc-nickel rust prevention treatment was performed at a temperature of 40° C. and a current density of 0.5 A/dm ² . Note that the surface of the electrolytic copper foil of Example 8 opposite to the roughened surface was subjected to zinc-nickel rust prevention treatment under the same conditions as Examples 1 to 7 and 9 to 18.

(4) Chromate treatment Chromate treatment was performed on both sides of the electrolytic copper foil that had been subjected to the rust prevention treatment to form a chromate layer on the rust prevention treatment layer. This chromate treatment was performed under the conditions of chromic acid concentration of 1 g/L, pH of 11, liquid temperature of 25° C., and current density of 1 A/dm ² .

(5) Silane coupling agent treatment The chromate-treated copper foil described above 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 the silane coupling agent using pure water as a solvent onto the roughened surface using a shower ring and adsorbing it. The silane coupling agent was 3-aminopropyltrimethoxysilane in Examples 1 to 5, 9 and 14 to 18, 3-glycidoxypropyltrimethoxysilane in Examples 6 and 10 to 13, and 3-acryloxypropyl in Example 7. Trimethoxysilane, in Example 8 vinyltrimethoxysilane was used. The concentration of the silane coupling agent was 3 g/L in all cases. After adsorption of the silane coupling agent, the water was finally evaporated using 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.

(a) Surface quality parameters of the roughened surface The roughened surface of the roughened copper foil was measured in accordance with ISO25178 by surface roughness analysis using a laser microscope (OLS-5000, manufactured by Olympus Corporation). went. Specifically, the surface profile of a 129.419 μm x 128.704 μm area on the roughened surface of the roughened copper foil was measured using the laser microscope described above at an objective lens magnification of 100 times. The surface profile of the obtained roughened surface was analyzed according to the conditions shown in Table 2, and the skewness Ssk, protruding peak height Spk, ten-point average height S10z, developed area ratio of the interface Sdr, and polar point were analyzed. The height Sxp was calculated. Note that the ten-point average height S10z was calculated under two conditions (5 μm and 64 μm) for the cutoff wavelength by the L filter. Furthermore, based on the values of the obtained skewness Ssk, protruding peak height Spk, and ten-point average height S10z (L filter: 5 μm), the microparticle tip diameter index Spk/Ssk and the microparticle tip roughness index S10z/ The value of Ssk was calculated for each. The results were as shown in Table 3.

(b) Peel strength between copper foil and base material In order to evaluate the adhesion to the insulating base material for roughened copper foil under normal conditions and after heat load, measurement of normal peel strength and peel strength after solder float. was carried out as follows.

(b-1) Normal peel strength Two sheets of prepreg (thickness: 100 μm) containing polyphenylene ether, triallyl isocyanurate, and bismaleimide resin as main components were prepared and stacked as insulating base materials. The manufactured surface-treated copper foil was laminated on this stacked prepreg so that its roughened surface was in contact with the prepreg, and pressed at 32 kgf/cm ² and 205° C. for 120 minutes to produce a copper-clad laminate. . Next, a circuit was formed on this copper-clad laminate by etching to produce a test board with a 3 mm wide linear circuit. In addition, for Examples 9 and 16, before circuit formation, etching was performed on the copper foil side surface of the copper clad laminate until the thickness of the copper foil was 18 μm. The linear circuit thus obtained was peeled off from the insulating base material according to method A (90° peeling) of JIS C 5016-1994, and the normal peel strength (kgf/cm) was measured. The obtained normal peel strength was graded and evaluated based on the following criteria. The results were as shown in Table 3.
<Normal peel strength evaluation criteria>
- Evaluation A: Normal peel strength is 0.42 kgf/cm or more - Evaluation B: Normal peel strength is 0.40 kgf/cm or more and less than 0.42 kgf/cm - Evaluation C: Normal peel strength is less than 0.40 kgf/cm

(b-2) Peel strength after solder float Prior to measuring peel strength, the test board with the linear circuit was floated in a solder bath at 260°C for 20 seconds, but the procedure was the same as that for the normal peel strength described above. The peel strength (kgf/cm) after solder float was measured. The obtained peel strength after solder float was graded and evaluated based on the following criteria. The results were as shown in Table 3.
<Peeling strength evaluation criteria after solder float>
- Evaluation A: Peel strength after solder float is 0.41 kgf/cm or more - Evaluation B: Peel strength after solder float is 0.39 kgf/cm or more and less than 0.41 kgf/cm - Evaluation C: Peel strength after solder float is 0.41 kgf/cm or more. Less than 39kgf/cm

(c) Transmission characteristics A high frequency base material (MEGTRON6N, manufactured by Panasonic) was prepared as an insulating resin base material. A roughened copper foil was laminated on both sides of this insulating resin base material so that the roughened surface was in contact with the insulating resin base material, and using a vacuum press machine, the temperature was 190°C and the pressing time was 120 minutes. A copper-clad laminate with an insulation thickness of 136 μm was obtained. Thereafter, the copper-clad laminate was etched to obtain a substrate for transmission loss measurement in which a microstrip line was formed so that the characteristic impedance was 50Ω. The transmission loss (dB/cm) of the obtained transmission loss measurement substrate was measured at 50 GHz using a network analyzer (manufactured by Keysight Technologies, N5225B). The obtained transmission loss was graded and evaluated based on the following criteria. The results were as shown in Table 3.
<Transmission loss evaluation criteria>
- Evaluation A: Transmission loss is -0.57 dB/cm or more - Evaluation B: Transmission loss is -0.70 dB/cm or more and less than -0.57 dB/cm - Evaluation C: Transmission loss is less than -0.70 dB/cm

Claims (10)

A roughened copper foil having a roughened surface on at least one side,
The roughened surface has a cutoff wavelength of S filter according to ISO 25178 with respect to skewness Ssk measured under conditions of a cutoff wavelength of 0.3 μm with S filter and 5 μm with L filter according to ISO 25178. The microparticle tip diameter index Spk/Ssk, which is the ratio of the protruding peak height Spk (μm) measured under the conditions of 0.3 μm and a cutoff wavelength of 5 μm using an L filter, is 0.20 or more and 1.00 or less, Microparticle tip roughness, which is the ratio of the ten-point average height S10z (μm) measured under the conditions of a cutoff wavelength of 0.3 μm with an S filter and a cutoff wavelength of 5 μm with an L filter, in accordance with ISO 25178, to the skewness Ssk. The ten-point average is measured under the conditions that the density index S10z/Ssk is 1.00 or more and 6.00 or less, and the cutoff wavelength is 0.3 μm with the S filter and 64 μm with the L filter in accordance with ISO 25178. A roughened copper foil having a height S10z of 2.50 μm or more and 10.00 μm or less . The roughened surface has an interface developed area ratio Sdr of 22.00% or more, measured under the conditions of a cutoff wavelength of 0.3 μm by an S filter and a cutoff wavelength of 64 μm by an L filter in accordance with ISO 25178. The roughened copper foil according to claim 1 . The roughened surface has a skewness Ssk of 0.40 or more and 1.20 or less measured under the conditions of a cutoff wavelength of 0.3 μm by an S filter and a cutoff wavelength of 5 μm by an L filter in accordance with ISO 25178. Item 2. Roughening treated copper foil according to item 1 or 2 . The roughened surface has a protruding peak height Spk of 0.25 μm or more and 0.80 μm or less, measured under the conditions of a cutoff wavelength of 0.3 μm by an S filter and a cutoff wavelength of 5 μm by an L filter in accordance with ISO 25178. The roughened copper foil according to any one of claims 1 to 3 . The roughened surface has a ten-point average height S10z (roughened particles S10z) of 1.5 μm, which is measured in accordance with ISO 25178 with a cutoff wavelength of 0.3 μm using an S filter and a cutoff wavelength of 5 μm using an L filter. The roughened copper foil according to any one of claims 1 to 4 , which has a diameter of 50 μm or more and 4.00 μm or less. The roughened surface has a pole height Sxp of 0.40 μm or more and 1.60 μm or less, measured under the conditions of a cutoff wavelength of 0.3 μm by an S filter and a cutoff wavelength of 5 μm by an L filter in accordance with ISO 25178. , the roughened copper foil according to any one of claims 1 to 5 . The roughened copper foil according to any one of claims 1 to 6 , further comprising a rust prevention treatment layer and/or a silane coupling agent treatment layer on the roughening treatment surface. The roughened copper foil according to any one of claims 1 to 7 , wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the opposite side of the electrode surface of the electrolytic copper foil. foil. A copper-clad laminate comprising the roughened copper foil according to any one of claims 1 to 8 . A printed wiring board comprising the roughened copper foil according to any one of claims 1 to 8 .

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