CN115413301A

CN115413301A - Roughened copper foil, copper-clad laminate, and printed wiring board

Info

Publication number: CN115413301A
Application number: CN202180023459.1A
Authority: CN
Inventors: 川口彰太; 立冈步; 加藤翼; 杨博钧
Original assignee: Mitsui Mining and Smelting Co Ltd
Current assignee: Mitsui Mining and Smelting Co Ltd
Priority date: 2020-03-23
Filing date: 2021-03-16
Publication date: 2022-11-29
Also published as: KR20220130189A; TW202206651A; TWI763387B; JPWO2021193246A1; WO2021193246A1; JP7374298B2

Abstract

Provided is a roughened copper foil which can achieve both excellent transmission characteristics and high peel strength when used in a copper-clad laminate and/or a printed wiring board. The roughened copper foil has a roughened surface on at least one side. The ratio of the projecting peak height Spk (μm) of the roughened surface measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 5 μm by the L filter according to ISO25178 to the skewness Ssk measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 5 μm by the L filter according to ISO25178, that is, the microparticle tip diameter index Spk/Ssk, is 0.20 or more and 1.00 or less, and the ten-point region height S10z measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 64 μm by the L filter according to ISO25178 is 2.50 μm or more.

Description

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

Technical Field

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

Background

In the process of manufacturing a printed wiring board, a copper foil is widely used in the form of a copper-clad laminate bonded to an insulating resin substrate. In this regard, in order to prevent peeling of the wiring during the production of the printed wiring board, it is desirable that the copper foil and the insulating resin base material have high adhesion. Therefore, in a typical copper foil for manufacturing a printed wiring board, unevenness including fine copper particles is formed by roughening a bonding surface of the copper foil, and the unevenness is embedded into the insulating resin base material by press working to exert an anchor effect, thereby improving adhesiveness.

As a copper foil subjected to such roughening treatment, for example, patent document 1 (japanese patent application laid-open No. 2018-172785) discloses a surface-treated copper foil having a copper foil and a roughening-treated layer on at least one surface of the copper foil, wherein an offset Ssk of the surface on the side of the roughening-treated layer is-0.6 or more and-0.35 or less, and a TD (width direction) gloss of the surface on the side of the roughening-treated layer is 70% or less. With such a surface-treated copper foil, it is possible to favorably suppress the falling off of the roughened particles provided on the surface of the copper foil, and to favorably suppress the generation of wrinkles and streaks when the copper foil is bonded to an insulating substrate. Patent document 1 also discloses a surface-treated copper foil in which the height Spk of the projecting crest on the side surface of the roughened layer is 0.13 μm or more and 0.27 μm or less for the purpose of obtaining the above-described effects.

On the other hand, with the recent development of higher functions of portable electronic devices and the like, signals are being increased in frequency for high-speed processing of large-capacity data, both in signal and analog, and printed wiring boards suitable for high-frequency applications are being demanded. In such a high-frequency printed circuit board, it is desirable to reduce transmission loss so that a high-frequency signal can be transmitted without being deteriorated. The printed wiring board includes a copper foil processed into a wiring pattern and an insulating base material, and the main loss of the transmission loss includes a conductor loss due to the copper foil and a dielectric loss due to the insulating base material.

In this regard, a roughened copper foil that realizes reduction of transmission loss has been proposed. For example, patent document 2 (japanese patent laid-open No. 2015-148011) discloses: for the purpose of providing a surface-treated copper foil having a small signal transmission loss, a laminate using the same, or the like, the surface treatment is used to control the skewness Rsk of the copper foil surface in accordance with JIS B0601-2001 to a predetermined range of-0.35 to 0.53.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-172785

Patent document 2: japanese patent laid-open publication No. 2015-148011

Disclosure of Invention

As described above, in recent years, improvement of transmission characteristics (high-frequency characteristics) of printed wiring boards has been demanded. In order to meet such a demand, a finer roughening treatment is attempted on the surface of the copper foil bonded to the insulating resin substrate. That is, in order to reduce the irregularities on the surface of the copper foil, which are factors that increase the transmission loss, it is considered to perform a fine roughening treatment on the surface of the copper foil having a small waviness (for example, the surface of a double-sided smooth foil, the electrode surface of an electrolytic copper foil). However, when the copper-clad laminate and/or the printed wiring board are processed using such a roughened copper foil, there is a problem that the peel strength between the copper foil and the substrate is generally low and the adhesion reliability is poor.

The present inventors have obtained the following findings: in the roughened surface of the copper foil, by controlling the ratio of the projected crest height Spk or the ten-point region height S10z to the skewness Ssk (Spk/Ssk or S10 z/Ssk) under the condition that the waviness component of the copper foil is removed and the ten-point region height S10z under the condition that the waviness component of the copper foil is reflected within a predetermined range, it is possible to achieve both excellent transmission characteristics and high peel strength in the copper-clad laminate and/or printed wiring board manufactured using the same.

Accordingly, an object of the present invention is to provide a roughened copper foil which can achieve both excellent transmission characteristics and high peel strength when used for a copper-clad laminate and/or a printed circuit board.

According to one embodiment of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side,

the ratio of the peak projecting height Spk (μm) of the roughened surface measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 5 μm by the L filter to the skewness Ssk measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 5 μm by the L filter, i.e., the particle tip diameter index Spk/Ssk, according to ISO25178 is 0.20 or more and 1.00 or less, and the ten point region height S10z measured under the conditions of a cut-off wavelength of 0.3 μm by the S filter and a cut-off wavelength of 64 μm by the L filter according to ISO25178 is 2.50 μm or more.

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 ten-point region height S10z (μm) measured according to ISO25178 under the condition that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 5 μm, which is a ratio of a skewness Ssk measured according to ISO25178 under the conditions that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 5 μm, i.e., a particle front end roughness index S10z/Ssk is 1.00 or more and 6.00 or less, and a ten-point region height S10z measured according to ISO25178 under the conditions that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 64 μm is 2.50 μm or more.

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

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

Drawings

Fig. 1A is a diagram for explaining the skewness Ssk determined in accordance with ISO25178, and is a diagram showing a surface and its height distribution when Ssk < 0.

Fig. 1B is a diagram for explaining the skewness Ssk determined in accordance with ISO25178, and is a diagram showing a surface and its height distribution when Ssk > 0.

Fig. 2 is a diagram for explaining a load curve and a load area ratio determined in accordance with ISO 25178.

Fig. 3 is a diagram for explaining a load area ratio Smr1 separating the protrusion peak portions from the central portion, and a load area ratio Smr2 separating the protrusion valley portions from the central portion, determined in accordance with ISO 25178.

Fig. 4 is a diagram for explaining the pole height Sxp determined in accordance with ISO 25178.

Fig. 5 is a view for explaining a case where the surface irregularities of the roughened copper foil include a roughened particle component and a waviness component.

FIG. 6 is a schematic view showing an example of a roughened copper foil of the present invention.

Detailed Description

Definition of

The following illustrates definitions of terms and/or parameters used to define the present invention.

In the present specification, "skewness Ssk" means: parameters representing the symmetry of the height distribution, measured according to ISO 25178. When the value is 0, the height distribution is vertically symmetrical. As shown in fig. 1A, when this value is less than 0, the surface has many fine valleys. On the other hand, as shown in fig. 1B, when the value is larger than 0, the surface shows many fine peaks.

In the present specification, "load curve of a plane" (hereinafter simply referred to as "load curve") means: curve representing the load area ratio from 0% to 100% height, determined according to ISO 25178. The load area ratio is a parameter indicating the area of a region having a certain height c or more as shown in fig. 2. The load area ratio at the height c corresponds to Smr (c) in fig. 2. As shown in fig. 3, a secant of the load curve, which is drawn along the load curve with the difference in load area ratio being 40% from 0% of the load area ratio, is taken, and the secant of the load curve is moved from 0% of the load area ratio, and the position where the slope of the secant is most gentle is referred to as the center portion of the load curve. The straight line having the smallest sum of squares of deviations from the longitudinal axis direction with respect to the central portion is referred to as an equivalent straight line. The portion included in the range of the height of the load area ratio of 0% to 100% of the straight equivalent line is referred to as the center portion. The portion higher than the central portion is referred to as a projecting peak, and the portion lower than the central portion is referred to as a projecting valley.

The "projecting peak height Spk" in this specification means: the average height of the projecting peaks on the central part, determined according to ISO 25178.

In the present specification, "pole height Sxp" means: the parameters representing the height difference between the area load ratio p% and the area load ratio q% measured according to ISO25178 are shown in fig. 4. Sxp represents the difference in height of the mean plane of the surface and the peak of the surface after removal of the particularly high peak in the surface. In this specification, sxp employs a height difference between a load area rate of 2.5% and a load area rate of 50%.

In the present specification, "ten-point region height S10z" means: the sum of the average height of the peak top from the high peak to the 5 th high peak and the average depth (positive value) of the valley bottom from the deep valley to the 5 th deep valley, among the peak top and the valley bottom in the reference region.

In the present specification, "interface spread area ratio Sdr" means: a parameter which expresses in percentage how much the extended area (surface area) of a defined region increases relative to the area of a defined region, measured in accordance with ISO 25178. The smaller this value, the closer to a flat surface shape, and the Sdr of the completely flat surface is 0%. On the other hand, the larger the value, the more uneven the surface shape.

In the present specification, the "diameter index of the leading end of fine particle Spk/Ssk" means: the ratio of the projected peak height Spk (μm) to the skew degree Ssk. In the present specification, the "particle front end roughness index S10z/Ssk" means: the ten-dot region height S10z (μm) to the skew degree Ssk.

The skewness Ssk, the projected ridge height Spk, the pole height Sxp, the ten-point region height S10z, and the interface spread area ratio Sdr can be calculated by measuring the surface profile of a predetermined measurement area (for example, a two-dimensional region of 129.419 μm × 128.704 μm) on the roughened surface with a commercially available laser microscope.

In the present specification, the skewness Ssk, the projected crest height Spk, and the pole height Sxp are measured under the conditions that the cutoff wavelength by the S filter is 0.3 μm and the cutoff wavelength by the L filter is 5 μm. In the present specification, the interfacial spreading area ratio Sdr is measured under the conditions that the cutoff wavelength by the S filter is 0.3 μm and the cutoff wavelength by the L filter is 64 μm. Further, in the present specification, the ten-point region height S10z is measured under the condition that the cutoff wavelength by the S filter is 0.3 μm and the cutoff wavelength by the L filter is 5 μm when used for calculating the particle tip roughness S10z/Ssk (hereinafter, the ten-point region height S10z measured under the condition may be referred to as "ten-point region height S10z (roughening particles S10 z)" as occasion demands). On the other hand, when the calculation is performed for other than the particle front end roughness S10z/Ssk, the ten-point region height S10z is measured under the conditions that the cutoff wavelength by the S filter is 0.3 μm and the cutoff wavelength by the L filter is 64 μm (hereinafter, the ten-point region height S10z measured under the conditions may be referred to as "ten-point region height S10z (entire S10 z)", as needed).

In the present specification, the "electrode surface" of the electrolytic copper foil refers to a surface which is in contact with a cathode during the production of the electrolytic copper foil.

In the present specification, the "deposition surface" of the electrolytic copper foil means a surface on which electrolytic copper is deposited in the production of the electrolytic copper foil, that is, a surface on which the electrolytic copper is not in contact with the cathode.

Roughened copper foil

The copper foil of the present invention is a roughened copper foil. The roughened copper foil has a roughened surface on at least one side. The roughened surface has a ratio of the projecting peak height Spk (μm) to the skewness Ssk, i.e., a particle front end diameter index Spk/Ssk of 0.20 to 1.00, and a ten-point region height S10z (overall S10 z) of 2.50 μm or more, and/or a ratio of the ten-point region height S10z (roughened particles S10 z) (μm) to the skewness Ssk, i.e., a particle front end roughness index S10z/Ssk of 1.00 to 6.00, and a ten-point region height S10z (overall S10 z) of 2.50 μm or more. In this way, in the roughened copper foil, spk/Ssk or S10z/Ssk under the condition that the waviness component of the copper foil is removed and S10z under the condition that the waviness component of the copper foil is reflected are controlled to be in predetermined ranges, so that the copper-clad laminate and/or the printed wiring board manufactured using the roughened copper foil can satisfy both excellent transmission characteristics (high-frequency characteristics) and high peel strength (for example, normal peel strength and post-heat load peel strength).

It is difficult to achieve both excellent transmission characteristics and high peel strength. This is because: in order to obtain excellent transmission characteristics, it is required to reduce the surface roughness of the copper foil, and in order to obtain high peel strength, it is required to increase the surface roughness of the copper foil, and both are in a trade-off relationship. Here, as shown in fig. 5, the irregularities on the roughened copper foil surface include a "roughened particle component" and a "waviness component" that is longer in period than the roughened particle component. In general, in order to obtain excellent transmission characteristics, it is considered to form small roughened particles by performing fine roughening treatment on the surface of a copper foil having a small waviness (for example, the surface of a double-sided smooth foil or the electrode surface of an electrolytic copper foil), but when a copper-clad laminate and/or a printed wiring board is produced using such a roughened copper foil, the peel strength between the copper foil and a substrate is generally low.

In view of the above problem, the present inventors have studied the influence of the roughened particles of the irregularities of the copper foil surface and the waviness on the transmission characteristics and the peel strength. As a result, it was found that the waviness component of the copper foil is contrary to expectation, and hardly affects the transmission characteristics, and mainly the size of the roughening particles affects the transmission characteristics. Then, the present inventors found out that: by evaluating the skewness Ssk and the height Spk of the projecting crest or the skewness Ssk and the height S10z of the ten-point region (the roughening particles S10 z) in combination under the condition that the waviness component of the copper foil is removed, the diameter of the tip and/or the roughness of the tip of the fine particles (the roughening particles) that affect the transmission characteristics can be accurately evaluated. Specifically, it was found that excellent transmission characteristics can be achieved by setting the particle front diameter index Spk/Ssk or the particle front roughness index S10z/Ssk of the roughened surface of the roughened copper foil within the above-mentioned range. Further, it has been found that by setting the ten-point region height S10z (the entire S10 z) in the above range under the condition that the waviness component of the copper foil is reflected, even small roughened particles which originally make it difficult to secure the peel strength can realize a high peel strength between the copper foil and the substrate by the waviness of the copper foil. As described above, the roughened copper foil according to the present invention can achieve both excellent transmission characteristics and high peel strength when used for a copper-clad laminate and/or a printed circuit board.

The roughened particle component and the waviness component of the copper foil surface can be distinguished by using an S filter and an L filter of a laser microscope. Specifically, parameters of the components of the roughened particles, in which the influence of the waviness component is removed, can be obtained by measuring the roughened surface of the roughened copper foil under the conditions that the cutoff wavelength of the S filter is 0.3 μm and the cutoff wavelength of the L filter is 5 μm. Therefore, it can be said that the skewness Ssk, the peak height Spk, the pole height Sxp, the ten-point region height S10z (roughening particles S10 z), the grain front diameter index Spk/Ssk, and the grain front roughness index S10z/Ssk in the present invention accurately reflect the parameters of the roughening particles of the copper foil surface. On the other hand, by measuring the surface of the copper foil under the conditions that the cutoff wavelength by the S filter is 0.3 μm and the cutoff wavelength by the L filter is 64 μm, the overall parameters reflecting the influence of both the coarsened grain component and the waviness component can be obtained. Therefore, the interfacial expansion area ratio Sdr and the ten-point region height S10z (the entire S10 z) in the present invention can be said to be parameters reflecting not only the roughened particle component but also the waviness component of the copper foil surface.

According to one embodiment of the present invention, the index Spk/Ssk of the particle tip diameter of the roughened surface of the roughened copper foil is 0.20 μm or more and 1.00 μm or less, preferably 0.30 μm or more and 0.90 μm or less, more preferably 0.40 μm or more and 0.80 μm or less, and particularly preferably 0.50 μm or more and 0.75 μm or less. The skewness Ssk of the roughened surface of the roughened copper foil is preferably 0.40 to 1.20, more preferably 0.45 to 1.17, still more preferably 0.50 to 1.14, and particularly preferably 0.55 to 1.10 μm. Further, the height Spk of the projecting peak of the roughened surface of the roughened copper foil is preferably 0.25 μm or more and 0.80 μm or less, more preferably 0.40 μm or more and 0.80 μm or less, still more preferably 0.40 μm or more and 0.78 μm or less, and particularly preferably 0.42 μm or more and 0.76 μm or less. As described above, in the present invention, the skew Ssk, the projecting crest height Spk, and the particle tip diameter index Spk/Ssk are not affected by the waviness component of the unevenness of the copper foil surface, and therefore, the precise value of the fine tip diameter of the roughened particle which affects the transmission characteristics can be measured. In this regard, when the skewness Ssk, the projecting peak height Spk, and/or the particle tip diameter index Spk/Ssk are within the above-described ranges, a high peel strength is obtained, and more excellent transmission characteristics can be achieved.

According to another aspect of the present invention, the grain front roughness index S10z/Ssk of the roughened surface of the roughened copper foil is 1.00 μm or more and 6.00 μm or less, preferably 1.50 μm or more and 6.00 μm or less, more preferably 2.00 μm or more and 6.00 μm or less, and particularly preferably 2.00 μm or more and 5.50 μm or less. The skewness Ssk of the roughened surface of the roughened copper foil is preferably 0.40 to 1.20, more preferably 0.45 to 1.17, still more preferably 0.50 to 1.14, and particularly preferably 0.55 to 1.10 μm. Further, the ten-point region height S10z (roughened particle S10 z) of the roughened surface of the roughened copper foil is preferably 1.50 μm or more and 4.00 μm or less, more preferably 2.00 μm or more and 4.00 μm or less, further 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 described above, in the present invention, since the skewness Ssk, the ten-point region height S10z (the roughening particle S10 z) and the particle front end roughness index S10z/Ssk remove the influence of the waviness component of the unevenness of the copper foil surface, it is possible to measure the accurate value of the minute front end roughness of the roughening particle which affects the transmission characteristics. In this regard, when the skewness Ssk, the ten-point region height S10z (roughening particles S10 z), and/or the particle front end roughness index S10z/Ssk are within the above-described ranges, high peel strength is obtained, and more excellent transmission characteristics can be realized.

The height S10z (the entire S10 z) of the ten-point region of the roughened surface of the roughened copper foil is 2.50 μm or more, preferably 2.50 μm or more and 10.00 μm or less, more preferably 2.90 μm or more and 9.00 μm or less, still more preferably 3.30 μm or more and 8.00 μm or less, and particularly preferably 3.70 μm or more and 7.00 μm or less. The ten-point region height S10z (S10 z as a whole) reflects the waviness component of the unevenness of the copper foil surface, and as described above, when the ten-point region height S10z (S10 z as a whole) is within the above range, excellent transmission characteristics are obtained, and high peel strength between the copper foil and the substrate can be achieved by the waviness of the copper foil.

The interface spread area ratio Sdr of the roughened surface of the roughened copper foil is preferably 22.00% or more, more preferably 25.00% or more, further preferably 30.00%, further more preferably 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 interfacial expansion area ratio Sdr is within the above range, the dielectric characteristics are excellent, and the roughened surface has a shape rich in irregularities suitable for achieving higher peel strength.

The pole height Sxp of the roughened surface of the roughened copper foil is preferably 0.40 μm or more and 1.60 μm or less, more preferably 0.50 μm or more and 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 a height difference between the average surface of the surface and the peak of the surface, and when the pole height Sxp is within the above range, the anchor effect is effectively exerted, and higher peel strength can be achieved.

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. The roughened copper foil of the present invention is not limited to a roughened copper foil obtained by roughening the surface of a normal copper foil, and may be a roughened copper foil obtained by roughening and/or micro-roughening the surface of a copper foil with a carrier copper foil.

Fig. 6 shows an example of the roughened copper foil of the present invention. As shown in fig. 6, the roughened copper foil of the present invention is preferably produced by performing roughening treatment on a surface of a copper foil having a prescribed waviness (for example, a precipitation surface of an electrolytic copper foil) under a desired low-roughening condition 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 side opposite to the electrode surface (i.e., on the deposition surface side) of the electrolytic copper foil. The roughened copper foil may have roughened surfaces on both sides or only one side. The roughened surface is typically provided with a plurality of roughened particles, each of which is preferably formed of copper particles. The copper particles may be formed of metallic copper or a copper alloy.

The roughening treatment for forming the roughened surface is preferably performed by forming roughened particles on the copper foil using copper or a copper alloy. The copper foil before roughening treatment may be a non-roughened copper foil or a pre-roughened copper foil. The cross-point height Rz of the microscopic unevenness of the surface of the roughened copper foil measured in accordance with JIS B0601-1994 is preferably 1.50 μm or more and 10.00 μm or less, more preferably 2.00 μm or more and 8.00 μm or less. When the amount is within the above range, the surface profile required for the roughened copper foil of the present invention can be easily imparted to the roughened surface.

As for the roughening treatment, for example, it is preferable that the copper sulfate solution containing copper at a concentration of 5g/L to 20g/L inclusive and sulfuric acid at a concentration of 50g/L to 200g/L inclusive is subjected to a roughening treatment at a temperature of 20A/dm inclusive at 20 ℃ to 40 ℃ inclusive ² Above and 50A/dm ² Electrolytic deposition was performed as follows. The electrolytic deposition 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 still more preferably for 1 second or more and 3 seconds or less. As another example, when 9-phenylacridine (9 PA) is added, it is preferable that copper sulfate solution containing copper and sulfuric acid at the above concentrations and containing chlorine at a concentration of 20mg/L to 100mg/L inclusive and 9PA at a concentration of 100mg/L to 200mg/L inclusive is subjected to a temperature of 20 ℃ to 40 ℃ inclusive at a temperature of 20A/dm inclusive ² Above and 200A/dm ² Electrolytic deposition was performed as follows. The electrolytic deposition is preferably performed for 0.3 seconds or more and 30 seconds or less, and more preferably for 0.5 seconds or more and 1.0 second or less. In the electrolytic deposition, the amount of inter-electrode copper supply defined by the following formula is preferably set to 0.1[ (g.m)/(min.L)]1.0[ (g.m)/(min.L) above]The following.

F _Cu ＝F _CuSO4 ×C _Cu /S

(in the formula, F _Cu Supplying the interelectrode copper in an amount [ (g.m)/(min.L)]、F _CuSO4 Is the flow rate (m) of the copper sulfate solution ³ Per minute), C _Cu Copper concentration (g/L) of copper sulfate solution, and S is anode-cathode cross-sectional area (m) ² ))

This makes it easy to impart the surface profile required for the roughened copper foil of the present invention to the surface of the roughened copper foil. Of course, the roughened copper foil according to the present invention is not limited to the above-described method, and can be produced by any method.

If desired, the roughened copper foil may be subjected to rust-proofing treatment to form a rust-proofing layer. The rust-preventive treatment preferably includes a plating treatment using zinc. The plating treatment using zinc may be any of a zinc plating treatment and a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy plating treatment. The zinc-nickel alloy plating treatment may be a plating treatment including 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 treatment layer, the treated surface of the roughened copper foil is more excellent in adhesion to a resin, chemical resistance, and heat resistance, and etching residues are less likely to remain. The Ni/Zn adhesion ratio in the zinc-nickel alloy plating treatment is preferably 1.2 or more and 10 or less, more preferably 2 or more and 7 or less, and further preferably 2.7 or more and 4 or less in terms of a mass ratio. In addition, the rust-preventive treatment preferably further includes chromate treatment, and the chromate treatment is preferably performed on the surface of the plating layer including zinc after the plating treatment using zinc. This can further improve the rust prevention property. A particularly preferred rust inhibiting treatment is a combination of a zinc-nickel alloy plating treatment and a subsequent chromate treatment.

If desired, the roughened copper foil may be subjected to a silane coupling agent treatment on the surface thereof to form a silane coupling agent layer. This improves moisture resistance, chemical resistance, adhesion to adhesives and the like. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, applying the diluted silane coupling agent, and drying the silane coupling agent. Examples of the silane coupling agent include: epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane; or amino-functional 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; or a mercapto-functional silane coupling agent such as 3-mercaptopropyltrimethoxysilane; or olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane; or acrylic functional silane coupling agents such as 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane; or imidazole-functional silane coupling agents such as imidazole silane; and triazine functional silane coupling agents such as triazine silane.

For the above reasons, the roughened copper foil preferably further includes an antirust treated layer and/or a silane coupling agent layer on the roughened surface, and more preferably includes both an antirust treated layer and a silane coupling agent layer. The rust-preventive treatment 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 laminated board

The roughened copper foil of the present invention is preferably used for the production of a copper-clad laminate for a printed wiring board. That is, according to a preferred embodiment of the present invention, there is provided a copper-clad laminate including the roughened copper foil. By using the roughened copper foil of the present invention, the copper-clad laminate can achieve both excellent dielectric characteristics and high peel strength. The copper-clad laminate comprises: the invention provides a roughened copper foil 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 is made of a resin, preferably an insulating resin. The resin layer is preferably a prepreg and/or a resin sheet. The prepreg is a generic name of a composite material in which a synthetic resin is impregnated into a base material such as a synthetic resin plate, a glass woven fabric, a glass nonwoven fabric, or paper. Preferable examples of the insulating resin include epoxy resin, cyanate resin, bismaleimide-triazine resin (BT resin), polyphenylene ether resin, and phenol resin. Examples of the insulating resin constituting the resin sheet include insulating resins such as epoxy resin, polyimide resin, and polyester resin. In addition, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina, from the viewpoint of improving insulation 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 further preferably 3 μm or more and 200 μm or less. The resin layer may be composed of a plurality of layers. The resin layer such as a prepreg and/or a resin sheet may be provided on the roughened copper foil through a primer resin layer applied to the surface of the copper foil in advance.

Printed circuit board

The roughened copper foil of the present invention is preferably used for the production of printed wiring boards. That is, according to a preferred embodiment of the present invention, there is provided a printed wiring board including the above-described roughened copper foil. By using the roughened copper foil of the present invention, a printed wiring board can achieve both excellent transmission characteristics and high peel strength. The printed wiring board according to the present embodiment has a layered structure in which a resin layer and a copper layer are stacked. The copper layer is a layer derived from the roughened copper foil of the present invention. In addition, as for the resin layer, as described above with respect to the copper-clad laminate. In any case, the printed circuit board may be constructed using known layers. Specific examples of the printed wiring board include a single-sided or double-sided printed wiring board obtained by bonding the roughened copper foil of the present invention to one or both sides of a prepreg, curing the copper foil to form a laminate, and then forming a circuit, a multilayer printed wiring board obtained by multilayering the laminate, and the like. Further, as other specific examples, a flexible printed wiring board, COF, TAB tape, and the like, in which the roughened copper foil of the present invention is formed on a resin film to form a circuit, can be cited. Further, as other specific examples, there may be mentioned: a resin-coated copper foil (RCC) obtained by coating the roughened copper foil with the resin layer, a laminated wiring board obtained by laminating the resin layer as an insulating adhesive layer on the printed circuit board, forming a circuit by a modified semi-additive (MSAP) method, a subtractive method or the like using the roughened copper foil as all or a part of the wiring layer, a laminated wiring board obtained by removing the roughened copper foil and forming a circuit by a semi-additive (SAP) method, and a direct build-up wafer (direct build-up on wafer) obtained by alternately repeating the lamination of the resin-coated copper foil on the semiconductor integrated circuit and the formation of the circuit.

Examples

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

Examples 1 to 18

The roughened copper foil of the present invention was produced as follows.

(1) Production of electrolytic copper foil

In examples 1 to 9 and 11 to 18, as the copper electrolytic solution, sulfuric acid-acid copper sulfate solution having the composition shown below was used, a titanium electrode was used as a cathode, a DSA (dimensionally stable anode) was used as an anode, and the solution temperature was 45 ℃ and the current density was 55A/dm ² Electrolytic copper foil A having a thickness shown in Table 1 was obtained by electrolysis. At this time, as the cathode, an electrode whose surface roughness was adjusted by polishing the surface with a polishing wheel of #1000 was used.

< composition of sulfuric acid-acid copper sulfate solution >

-copper concentration: 80g/L

-sulfuric acid concentration: 300g/L

-gelatin concentration: 5mg/L

-chlorine concentration: 30mg/L

On the other hand, in example 10, as the copper electrolytic solution, a sulfuric acid-acid copper sulfate solution having the composition shown below was used to obtain an electrolytic copper foil B having a thickness shown in table 1. In this case, conditions other than the composition of the sulfuric acid-acidic copper sulfate solution were the same as those of the 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

-diallyl dimethyl ammonium chloride polymer concentration: 50mg/L

-chlorine concentration: 40mg/L

(2) Roughening treatment

Among the electrode surfaces and deposition surfaces of the electrolytic copper foil described above, the deposition surface side was subjected to roughening treatment in examples 1 to 11 and 15 to 18, and the electrode surface side was subjected to roughening treatment in examples 12 to 14. The ten-point height Rz of the microscopic unevenness 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 is shown in Table 1.

The following roughening treatment (first roughening treatment) was performed for examples 1 to 9 and 14 to 17. The roughening treatment is performed as follows: in a copper electrolytic solution for roughening treatment (copper concentration: 5g/L to 20g/L, sulfuric acid concentration: 50g/L to 200g/L, liquid temperature: 30 ℃ C.), each example was electrolyzed and washed with water under the conditions of current density, time, and inter-electrode copper supply amount shown in Table 1.

In examples 10 to 13, the first roughening treatment, the second roughening treatment, and the third roughening treatment described below were performed in this order.

The first roughening treatment is carried out by: the copper electrolytic solution for roughening treatment (copper concentration: 5g/L to 20g/L, sulfuric acid concentration: 50g/L to 200g/L, liquid temperature: 30 ℃) was electrolyzed and performed under the conditions of current density, time, and inter-electrode copper supply amount shown in Table 1.

-the second roughening treatment is carried out by: in the copper electrolytic solution for rough treatment having the same composition as that of the first rough treatment, water washing was performed by electrolysis under the conditions of current density, time, and inter-electrode copper supply amount shown in table 1.

-the third roughening treatment is carried out by: in a copper electrolytic solution for graining treatment (copper concentration: 65g/L to 80g/L, sulfuric acid concentration: 50g/L to 200g/L, liquid temperature: 45 ℃ C.), water washing was performed by electrolysis under the conditions of current density, time, and inter-electrode copper supply amount shown in Table 1.

In example 18, the following roughening treatment (first roughening treatment) was performed. The roughening treatment is performed as follows: the roughening treatment was performed by electrolysis and washing with water under the conditions of current density, time, and inter-electrode copper supply shown in Table 1 in a copper electrolytic solution (copper concentration: 5g/L to 20g/L, sulfuric acid concentration: 50g/L to 200g/L, chlorine concentration: 20mg/L to 100mg/L, 9PA100mg/L to 200mg/L, and liquid temperature: 30 ℃ C.).

(3) Anti-rust treatment

The electrolytic copper foil after the roughening treatment was subjected to rust-proofing treatment shown in table 1. As the rust-preventive treatment, in examples 1 to 7 and 9 to 18, a pyrophosphate bath was used for both surfaces of the electrolytic copper foil so that the potassium pyrophosphate concentration was 80g/L, the zinc concentration was 0.2g/L, the nickel concentration was 2g/L, the liquid temperature was 40 ℃ and the current density was 0.5A/dm ² Performing zinc-nickel series rust prevention treatment. On the other hand, in example 8, the surface of the electrodeposited copper foil on the side where the roughening treatment was performed was set to have a potassium pyrophosphate concentration of 100g/L, a zinc concentration of 1g/L, a nickel concentration of 2g/L, a molybdenum concentration of 1g/L, a liquid temperature of 40 ℃ and a current density of 0.5A/dm ² Performing zinc-nickel series rust prevention treatment. The surface of the electrodeposited copper foil of example 8 opposite to the surface subjected to the roughening treatment was subjected to zinc-nickel-based rust-proofing treatment under the same conditions as in examples 1 to 7 and 9 to 18.

(4) Chromate treatment

Chromate treatment is performed on both surfaces of the electrolytic copper foil subjected to the above-described rust prevention treatment, and a chromate layer is formed on the rust prevention treatment layer. The chromate treatment is carried out at a chromic acid concentration of 1g/L, a pH of 11, a liquid temperature of 25 ℃ and a current density of 1A/dm ² Under the conditions of (1).

(5) Silane coupling agent treatment

The copper foil subjected to the chromate treatment is washed with water and immediately treated with a silane coupling agent so that the silane coupling agent is adsorbed on the chromate layer on the roughened surface. The silane coupling agent treatment is performed by performing adsorption treatment by blowing a silane coupling agent solution containing pure water as a solvent onto the roughened surface by spraying. As the silane coupling agent, 3-aminopropyltrimethoxysilane was used in examples 1 to 5, 9 and 14 to 18, 3-glycidoxypropyltrimethoxysilane was used in examples 6 and 10 to 13, 3-acryloxypropyltrimethoxysilane was used in example 7, and vinyltrimethoxysilane was used in example 8. The concentration of each silane coupling agent was set to 3g/L. After the adsorption of the silane coupling agent, water was evaporated by a final electric heater to obtain a roughened copper foil having a predetermined thickness.

[ Table 1]

Evaluation of

The produced roughened copper foil was subjected to various evaluations as shown below.

(a) Surface property parameters of 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). Specifically, the surface profile of the 129.419. Mu. M.times.128.704. Mu.m area of the roughened surface of the roughened copper foil was measured at 100 times the objective magnification by the laser microscope. The surface profile of the obtained roughened surface was analyzed under the conditions shown in table 2, and the skewness Ssk, the projected crest height Spk, the ten-point region height S10z, the interface spread area ratio Sdr, and the pole height Sxp were calculated. The ten-point region height S10z was calculated by setting the cutoff wavelength by the L filter to 2 conditions (5 μm and 64 μm). Further, values of the microparticle tip diameter index Spk/Ssk and the microparticle tip roughness index S10z/Ssk are calculated based on the obtained values of the skewness Ssk, the projected crest height Spk, and the ten-point region height S10z (L filter: 5 μm), respectively. The results are shown in Table 3.

[ Table 2]

TABLE 2

(b) Peel strength between copper foil and substrate

For the roughened copper foil in the normal state and after thermal load, the peel strength in the normal state and the peel strength after immersion in tin (solder float) were measured as follows in order to evaluate the adhesiveness to the insulating base material.

(b-1) Normal Peel Strength

2 sheets of a prepreg (thickness: 100 μm) mainly composed of polyphenylene ether, triallyl isocyanurate, and bismaleimide resin were prepared as an insulating substrate and stacked. The surface-treated copper foil thus produced was laminated on the stacked prepreg so that the roughened surface thereof was in contact with the prepreg, and the lamination was carried out at 32kgf/cm ² And pressing at 205 ℃ for 120 minutes to produce a copper-clad laminate. Then, a circuit was formed on the copper-clad laminate by etching, and a test substrate having a linear circuit with a width of 3mm was manufactured. In examples 9 and 16, the copper foil side surface of the copper-clad laminate was etched until the thickness of the copper foil was 18 μm before the circuit was formed. The thus obtained linear circuit was peeled from the insulating substrate according to JIS C5016-1994 method A (90 ℃ peeling) and the normal state peel strength (kgf/cm) was measured. The obtained normal peel strength was evaluated in a classification manner according to the following criteria. The results are shown in Table 3.

< evaluation criteria for Normal peeling Strength >

-evaluation a: a normal state peel strength of 0.42kgf/cm or more

-evaluation B: a normal state peel strength of 0.40kgf/cm or more and less than 0.42kgf/cm

-evaluation C: normal state peel strength of less than 0.40kgf/cm

(b-2) Peel Strength after immersion tin

The peel strength (kgf/cm) after the wicking was measured by the same procedure as the above-described normal peel strength except that the test substrate having the linear circuit was immersed in the solder bath at 260 ℃ for 20 seconds before the measurement of the peel strength. The peel strength after the immersion tin obtained was evaluated in grades according to the following criteria. The results are shown in Table 3.

< evaluation criteria for peel strength after immersion in tin >

-evaluation a: the peel strength after tin immersion is more than 0.41kgf/cm

-evaluation B: the peel strength after tin immersion is more than 0.39kgf/cm and less than 0.41kgf/cm

-evaluation C: the peel strength after tin immersion is less than 0.39kgf/cm

(c) Transmission characteristic

A high-frequency base material (MEGTRON 6N, manufactured by Panasonic Corporation) was prepared as an insulating resin base material. The roughened copper foil was laminated on both surfaces of the insulating resin base material so that the roughened surface of the copper foil was in contact with the insulating resin base material, and the copper foil was laminated using a vacuum press at 190 ℃ for 120 minutes to obtain a copper-clad laminate having an insulation thickness of 136 μm. Then, the copper-clad laminate was subjected to etching processing, thereby obtaining a transmission loss measurement substrate in which a microstrip line was formed so that the characteristic impedance became 50 Ω. The transmission loss (dB/cm) at 50GHz was measured using a network analyzer (N5225B, manufactured by Keysight Technologies) for the obtained substrate for transmission loss measurement. The obtained transmission loss was evaluated in a classification manner according to the following criteria. The results are shown in Table 3.

< evaluation criteria for Transmission loss >

-evaluation a: transmission loss of-0.57 dB/cm or more

-evaluation B: the transmission loss is more than-0.70 dB/cm and less than-0.57 dB/cm

-evaluation C: transmission loss lower than-0.70 dB/cm

[ Table 3]

Claims

1. A roughened copper foil having a roughened surface on at least one side,

the roughened surface has a ratio of a projected peak height Spk (μm) measured according to ISO25178 under a condition that the S-filter has a cutoff wavelength of 0.3 μm and the L-filter has a cutoff wavelength of 5 μm to a skewness Ssk measured according to ISO25178 under a condition that the S-filter has a cutoff wavelength of 0.3 μm and the L-filter has a cutoff wavelength of 5 μm, that is, a microparticle tip diameter index Spk/Ssk of 0.20 to 1.00, and a ten-point region height S10z of 2.50 μm or more measured according to ISO25178 under a condition that the S-filter has a cutoff wavelength of 0.3 μm and the L-filter has a cutoff wavelength of 64 μm.

2. A roughened copper foil having a roughened surface on at least one side,

the roughened surface has a ten-point region height S10z (μm) measured according to ISO25178 under the conditions of a cut-off wavelength of 0.3 μm for an S filter and a cut-off wavelength of 5 μm for an L filter, which is 1.00 or more and 6.00 or less with respect to the ratio of the skewness Ssk measured according to ISO25178 under the conditions of a cut-off wavelength of 0.3 μm for an S filter and a cut-off wavelength of 5 μm for an L filter, and a ten-point region height S10z of 2.50 μm or more measured according to ISO25178 under the conditions of a cut-off wavelength of 0.3 μm for an S filter and a cut-off wavelength of 64 μm for an L filter.

3. The roughened copper foil according to claim 1 or 2, wherein the roughened surface has an interfacial spreading area ratio Sdr of 22.00% or more as measured in accordance with ISO25178 under the conditions that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 64 μm.

4. The roughened copper foil according to any one of claims 1 to 3, wherein the roughened surface has a skew Ssk of 0.40 or more and 1.20 or less as measured in accordance with ISO25178 under conditions where the S-filter cut-off wavelength is 0.3 μm and the L-filter cut-off wavelength is 5 μm.

5. The roughened copper foil according to any one of claims 1 to 4, wherein the height of the projecting peak Spk of the roughened surface, as measured in accordance with ISO25178 under the conditions that the S-filter has a cutoff wavelength of 0.3 μm and the L-filter has a cutoff wavelength of 5 μm, is 0.25 μm or more and 0.80 μm or less.

6. The roughened copper foil according to any one of claims 1 to 5, wherein the roughened surface has a ten-point region height S10z (S10 z as a whole) of 2.50 μm or more and 10.00 μm or less as measured in accordance with ISO25178 under the conditions that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 64 μm.

7. The roughened copper foil according to any one of claims 1 to 6, wherein the roughened surface has a ten-point region height S10z (roughened particles S10 z) of 1.50 μm or more and 4.00 μm or less as measured in accordance with ISO25178 under the conditions that the S filter has a cutoff wavelength of 0.3 μm and the L filter has a cutoff wavelength of 5 μm.

8. The roughened copper foil according to any one of claims 1 to 7, wherein the pole height Sxp of the roughened surface, as measured in accordance with ISO25178 under the conditions that the S-filter cutoff wavelength is 0.3 μm and the L-filter cutoff wavelength is 5 μm, is 0.40 μm or more and 1.60 μm or less.

9. The roughened copper foil according to any one of claims 1 to 8, further comprising a rust-proofing treatment layer and/or a silane coupling agent treatment layer on the roughened surface.

10. The roughened copper foil according to any one of claims 1 to 9, wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the side of the electrolytic copper foil opposite to the electrode surface.

11. A copper-clad laminate comprising the roughened copper foil according to any one of claims 1 to 10.

12. A printed wiring board comprising the roughened copper foil according to any one of claims 1 to 10.