Roughened copper foil, carrier-attached copper foil, copper clad laminate plate, and printed wiring board

Abstract

There is provided a roughened copper foil (110) that can provide both excellent etchability and high shear strength in the processing of a copper-clad laminate (114) or the manufacture of a printed wiring board. This roughened copper foil (110) has a roughened surface on at least one side. The roughened surface has a developed interfacial area ratio Sdr of 3.50% or more and 12.00% or less as measured in accordance with ISO 25178 under conditions of a cutoff wavelength of the S filter of 0.55 μm and a cutoff wavelength of the L filter of 10 μm. This roughened copper foil (110) has a core level difference Sk of 0.15 μm or more and 0.35 μm or less as measured in accordance with ISO 25178 under conditions of a cutoff wavelength of the S filter of 0.55 μm and a cutoff wavelength of the L filter of 10 μm. Figure 5

Description

Roughened copper foil, carrier-attached copper foil, copper-clad laminates and printed wiring boards

[0001] The present invention relates to a roughened copper foil, a carrier-attached copper foil, a copper-clad laminate, and a printed wiring board.

[0002] In recent years, the modified semi-additive process (MSAP) has become widely adopted as a manufacturing method for printed wiring boards suitable for miniaturizing circuits. The MSAP method is suitable for forming extremely fine circuits, and to take advantage of its features, it is performed using a carrier-attached copper foil. For example, as shown in Figures 1 and 2, an ultra-thin copper foil 10 is pressed and adhered to an insulating resin substrate 11 having a base substrate 11a and a lower layer circuit 11b on it using a prepreg 12 and a primer layer 13 (step (a)). After the carrier (not shown) is peeled off, via holes 14 are formed by laser drilling as needed (step (b)). Chemical copper plating 15 is then applied (step (c)), followed by masking with a predetermined pattern using a dry film 16 by exposure and development (step (d)), and electrolytic copper plating 17 is then applied (step (e)). After removing the dry film 16 to form the wiring portion 17a (step (f)), unnecessary ultra-thin copper foil and the like between the adjacent wiring portions 17a and 17a is removed by etching over the entire thickness thereof (step (g)), thereby obtaining wiring 18 formed in a predetermined pattern. Here, it is common practice to roughen the surface of the ultra-thin copper foil 10 in order to improve the physical adhesion between the circuit and the board.

[0003] As a copper foil that has undergone such a roughening treatment, for example, Patent Document 1 (Japanese Patent No. 6462961) discloses a surface-treated copper foil in which a roughening treatment layer, a rust-proofing treatment layer, and a silane coupling layer are laminated in this order on at least one side of the copper foil. Patent Document 1 also discloses that, for the purpose of producing a printed wiring board with low transmission loss and excellent reflow heat resistance, the developed area ratio Sdr of the interface measured from the surface of the silane coupling layer of such a surface-treated copper foil is 8% or more and 140% or less, the root-mean-square surface gradient Sdq is 25° or more and 70° or less, and the aspect ratio Str of the surface texture is 0.25 or more and 0.79 or less.

[0004] In fact, several carrier-attached copper foils with excellent fine circuit formability using the MSAP method or the like have been proposed. For example, Patent Document 2 (WO 2016 / 117587) discloses a carrier-attached copper foil having an ultrathin copper foil in which the average distance between surface peaks on the release layer side is 20 μm or less and the maximum height difference of the waviness on the side opposite the release layer is 1.0 μm or less. This embodiment is said to achieve both fine circuit formability and laser processability. Furthermore, Patent Document 3 (JP 2018-26590 A) discloses a carrier-attached copper foil in which the ratio Sp / Spk of the maximum peak height Sp to the protruding peak height Spk according to ISO 25178 on the ultrathin copper layer side surface is 3.271 or more and 10.739 or less, with the aim of improving fine circuit formability.

[0005] Japanese Patent No. 6462961 International Publication No. 2016 / 117587 Japanese Patent Application Laid-Open No. 2018-26590

[0006] In recent years, in order to form even finer circuits using the above-mentioned MSAP method and the like, there has been a demand for even greater smoothing of copper foils and smaller roughening particles. However, while smoothing copper foils and smaller roughening particles improve the etching properties of copper foils, which are involved in circuit miniaturization, the physical adhesion between the copper foil and the substrate resin, etc., decreases. In particular, as circuits become thinner, the printed wiring board mounting process has become more prone to peeling due to the application of physical stress (i.e., shear stress) to the circuit from the lateral direction, resulting in a decrease in yield. In this regard, one of the physical adhesion indices between a circuit and a substrate is shear strength (shear strength), and in order to effectively avoid the above-mentioned circuit peeling, it is necessary to maintain the shear strength at a certain level or higher. However, in order to ensure a certain level of shear strength, the roughening particles of the copper foil must be made larger, which creates a problem in that it is difficult to achieve both this and etching properties.

[0007] The present inventors have now discovered that by imparting a surface profile to a roughened copper foil in which the developed area ratio Sdr of the interface and the level difference Sk of the core portion, as defined in ISO 25178, are controlled within predetermined ranges, it is possible to achieve both excellent etching properties and high shear strength in the processing of copper-clad laminates or the production of printed wiring boards.

[0008] Therefore, an object of the present invention is to provide a roughened copper foil that can achieve both excellent etching properties and high shear strength in the processing of copper-clad laminates or the production of printed wiring boards.

[0009] According to one aspect of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side, wherein the roughened surface has an interface developed area ratio Sdr of 3.50% or more and 12.00% or less, measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter, and a core level difference Sk of 0.15 μm or more and 0.35 μm or less, measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter.

[0010] According to another aspect of the present invention, there is provided a carrier-attached copper foil comprising a carrier, a release layer provided on the carrier, and the roughened copper foil provided on the release layer with the roughened surface facing outward.

[0011] According to yet another aspect of the present invention, there is provided a copper-clad laminate comprising the above-described roughened copper foil.

[0012] According to yet another aspect of the present invention, there is provided a printed wiring board comprising the above-described roughened copper foil.

[0013] FIG. 1 is a process flow diagram for explaining the MSAP method, showing the first half of the process (processes (a) to (d)). FIG. 2 is a process flow diagram for explaining the MSAP method, showing the second half of the process (processes (e) to (g)). FIG. 3 is a diagram for explaining the load curve and area load ratio determined in accordance with ISO 25178. FIG. 4 is a diagram for explaining the area load ratio Smr1 separating the protruding peaks and the core, the area load ratio Smr2 separating the protruding valleys and the core, and the level difference Sk of the core, all determined in accordance with ISO 25178. FIG. 5 is a schematic cross-sectional view showing an example of an evaluation laminate immediately before etching in circuit formability (etchability evaluation). FIG. 6 is a schematic diagram for explaining a method for measuring shear strength.

[0014] DEFINITIONS The following are definitions of terms or parameters used to define the present invention.

[0015] In this specification, the "interface developed area ratio Sdr" is a parameter that indicates the degree to which the developed area (surface area) of a defined region is increased relative to the area of ​​the defined region, as measured in accordance with ISO 25178. In this specification, the interface developed area ratio Sdr is expressed as the increase in surface area (%). The smaller this value, the closer the surface shape is to flatness, and the Sdr of a completely flat surface is 0%. On the other hand, the larger this value, the more irregular the surface shape is. For example, if the Sdr of a surface is 40%, this indicates that the surface area of ​​this surface has increased by 40% from a completely flat surface.

[0016] In this specification, the term "surface load curve" (hereinafter simply referred to as "load curve") refers to a curve that indicates the height at which the load area ratio changes from 0% to 100%, as measured in accordance with ISO 25178. The load area ratio is a parameter that indicates the area of ​​a region above a certain height c, as shown in FIG. 3. The load area ratio at height c corresponds to Smr(c) in FIG. 3. As shown in FIG. 4, a secant line of the load curve is drawn along the load curve from a load area ratio of 0% with a difference of 40%, and the secant line is moved from a load area ratio of 0% to the center of the load curve, and the position where the slope of the secant line is the gentlest is called the central part of the load curve. The straight line that minimizes the sum of squares of deviations in the vertical axis direction from this central part is called the equivalent line. The part of the equivalent line that falls within the height range of the load area ratio from 0% to 100% is called the core part. Parts higher than the core part are called protruding peaks, and parts lower than the core part are called protruding valleys.

[0017] In this specification, the "level difference Sk of the core portion" refers to the value obtained by subtracting the minimum height from the maximum height of the core portion, measured in accordance with ISO 25178, and is a parameter calculated from the difference in height between the areal load ratios of 0% and 100% on the equivalent line, as shown in FIG. 4.

[0018] In this specification, the "maximum height Sz" is a parameter that represents the distance from the highest point to the lowest point on the surface, measured in accordance with ISO25178.

[0019] In this specification, the "aspect ratio Str of surface texture" is a parameter that indicates the isotropy or anisotropy of the surface texture, measured in accordance with ISO 25178. Str ranges from 0 to 1, and typically, Str > 0.5 indicates strong isotropy, while Str < 0.3 indicates strong anisotropy.

[0020] In this specification, the "peak density Spd" is a parameter that represents the number of peaks per unit area, measured in accordance with ISO 25178, and counts only peaks that are greater than 5% of the maximum amplitude on the contoured surface. A large value of this parameter indicates a large number of contact points with other objects.

[0021] The developed area ratio Sdr of the interface, the level difference Sk of the core part, the maximum height Sz, the aspect ratio Str of the surface texture, and the density of peaks Spd are determined by the following equations: ２ The surface profile of the two-dimensional region (a two-dimensional region of the surface) can be calculated by measuring it using a commercially available laser microscope. In this specification, the values ​​of the developed area ratio Sdr of the interface, the level difference Sk of the core portion, the maximum height Sz, and the aspect ratio Str of the surface texture are measured using an S filter with a cutoff wavelength of 0.55 μm and an L filter with a cutoff wavelength of 10 μm. Furthermore, in this specification, the value of the peak density Spd is measured using an S filter with a cutoff wavelength of 3 μm and an L filter with a cutoff wavelength of 10 μm.

[0022] In this specification, the "electrode surface" of the carrier refers to the surface that was in contact with the cathode during the preparation of the carrier.

[0023] In this specification, the "deposition surface" of the carrier refers to the surface on which electrolytic copper is deposited during the preparation of the carrier, that is, the surface that is not in contact with the cathode.

[0024] Roughened Copper Foil The copper foil according to the present invention is a roughened copper foil. This roughened copper foil has a roughened surface on at least one side. This roughened surface has an interface developed area ratio Sdr of 3.50% or more and 12.00% or less, and a core level difference Sk of 0.15 μm or more and 0.35 μm or less. In this way, by imparting a surface profile in which the interface developed area ratio Sdr and the core level difference Sk are each controlled within a predetermined range in the roughened copper foil, it is possible to achieve both excellent etching properties and high shear strength in the processing of copper-clad laminates or the production of printed wiring boards.

[0025] Excellent etching properties and high shear strength are inherently difficult to achieve simultaneously. This is because, as mentioned above, improving the etching properties of copper foil generally requires the roughening particles to be small, while increasing the shear strength of the circuit generally requires the roughening particles to be large. In particular, shear strength is not simply proportional to the specific surface area and roughening height, which have traditionally been used for evaluation, and controlling it has been difficult. In this regard, the present inventors have discovered that in order to correlate with physical properties such as etching properties and shear strength, it is effective to evaluate it by combining the interfacial developed area ratio Sdr and the core level difference Sk. They have also found that by controlling these surface parameters within the above-mentioned specified ranges, a roughened copper foil can be obtained that has a fine surface with excellent etching properties and a nodule height and specific surface area that are favorable for ensuring high shear strength. As such, the roughened copper foil of the present invention can achieve excellent etching properties and high shear strength, thereby enabling both excellent fine circuit formation properties and high circuit adhesion in terms of shear strength. Conventionally, techniques for controlling the developed area ratio Sdr, root-mean-square surface gradient Sdq, and aspect ratio Str of the surface texture of a surface-treated copper foil have been known (see Patent Document 1, cited above). However, these parameters are all determined taking into account protruding peaks, and suppressing the occurrence of protruding peaks can result in all of these values ​​becoming too small. In response to this, the present inventors have discovered that by controlling the core level difference Sk, a parameter that does not include protruding peaks, and the developed area ratio Sdr, a parameter that includes protruding peaks, the occurrence of protruding peaks on the roughened surface can be suppressed and each roughening particle constituting the roughened surface can be configured to penetrate the resin evenly. This allows for the production of a roughened copper foil that has a fine surface with excellent etching properties, while also having a nodule height and specific surface area that are favorable for ensuring high shear strength.

[0026] From the viewpoint of realizing a good balance between excellent etching properties and high shear strength, the roughened copper foil has an interface developed area ratio Sdr of 3.50% to 12.00%, preferably 4.50% to 8.50%, more preferably 4.50% to 6.00%. Within such a range, a fine surface (roughening height) with excellent etching properties can be obtained, while a sufficient adhesive area with the resin laminated during the production of a copper-clad laminate or printed wiring board can be secured, and circuit adhesion in terms of shear strength is improved.

[0027] From the viewpoint of achieving a good balance between excellent etching properties and high shear strength, the roughened copper foil has a core level difference Sk on the roughened surface of 0.15 μm or more and 0.35 μm or less, preferably 0.23 μm or more and 0.35 μm or less, more preferably 0.25 μm or more and 0.35 μm or less. Within this range, the roughening particles constituting the roughened surface can penetrate evenly into the resin, while still providing a fine surface (roughening height) with excellent etching properties, thereby improving adhesion to the resin. In other words, if there are irregularities in the roughening treatment, the irregularities are thought to become protruding peaks on the roughened surface. However, such irregularities (protruding peaks) do not contribute to improving circuit adhesion in terms of shear strength. In this regard, the maximum height Sz and the like conventionally used for evaluation are parameters that include protruding peaks. Therefore, when attempting to improve circuit adhesion based on such parameters, the roughening height tends to increase, which in turn tends to reduce etching properties. In contrast, the core level difference Sk is a parameter that does not include protruding peaks, as described above. Therefore, by using the level difference Sk of the core portion as an evaluation index, it is possible to accurately obtain the optimal surface shape for improving adhesion with the resin, and as a result, it is also possible to suppress an increase in the roughening height.

[0028] The roughened copper foil preferably has a ratio of the level difference Sk (μm) of the core portion to the developed area ratio Sdr (%) of the interface on the roughened surface, Sk / Sdr, of 0.038 to 0.050, more preferably 0.045 to 0.050. Within this range, the unevenness of the roughened surface is further reduced in height, and not only is the unevenness of the roughened surface large (i.e., the surface area is large), but the height of the core portion can also be sufficiently secured. That is, the level difference Sk of the core portion is a parameter obtained excluding the protruding peaks, while the developed area ratio Sdr is a parameter obtained including the protruding peaks. Therefore, when the number of protruding peaks increases or decreases, the value of the level difference Sk of the core portion remains constant, but the value of the developed area ratio Sdr changes. Therefore, by controlling the ratio of the core level difference Sk to the developed area ratio Sdr within the above range, the generation of protruding peaks on the roughened surface can be suppressed, which allows the roughening particles constituting the roughened surface to easily penetrate into the resin on an even basis, thereby achieving a better balance between excellent etching properties and high shear strength.

[0029] The roughened copper foil preferably has a maximum height Sz (μm) on the roughened surface and a core level difference Sk (μm), where Sz × Sk is the product of 0.25 to 0.50, more preferably 0.36 to 0.50. Within this range, the uneven shape of the roughened surface is more suppressed from generating protruding peaks, making it more suitable for achieving a balanced combination of excellent etching properties and high shear strength. Furthermore, from the viewpoint of achieving a finer surface with better etching properties, the roughened surface of the roughened copper foil preferably has a maximum height Sz of 1.6 μm or less, more preferably 1.0 μm to 1.4 μm, and even more preferably 1.0 μm to 1.2 μm.

[0030] The roughened copper foil has a peak density Spd of 2.00 × 10 on the roughened surface. ４ mm －２ Above 3.00 x 10 ４ mm －２ It is preferably equal to or less than 2.20 × 10４ mm －２ Above 3.00 x 10 ４ mm －２ More preferably, 2.75 × 10 ４ mm －２ The above is 2.85 x 10 ４ mm －２ This ensures sufficient adhesion points with the resin to be laminated when manufacturing a copper-clad laminate or printed wiring board, and more effectively improves circuit adhesion in terms of shear strength.

[0031] The aspect ratio Str of the surface texture of the roughened copper foil is preferably 0.2 or more and 0.5 or less, more preferably 0.24 or more and 0.50 or less, and even more preferably 0.45 or more and 0.50 or less. Within such ranges, the roughened surface has a waviness that is favorable for adhesion with resin. As a result, while the surface is fine and has excellent etching properties, the circuit adhesion in terms of shear strength can be more effectively improved.

[0032] 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 5.0 μm or less, and even more preferably 1.0 μm or more and 3.0 μm or less. The roughened copper foil is not limited to a copper foil whose surface has been roughened, but may also be a copper foil whose surface has been roughened with a carrier. Here, the thickness of the roughened copper foil does not include the height of the roughening particles formed on the surface of the roughened surface (the thickness of the copper foil itself constituting the roughened copper foil). Copper foils having a thickness in the above range are sometimes referred to as ultrathin copper foils.

[0033] The roughened copper foil has a roughened surface on at least one side. That is, the roughened copper foil may have roughened surfaces on both sides, or may have a roughened surface on only one side. The roughened surface typically comprises a plurality of roughened particles (nodules), and each of these plurality of roughened particles is preferably copper particles. The copper particles may be made of metallic copper or a copper alloy.

[0034] The roughening treatment for forming the roughened surface can be preferably carried out by forming roughening particles of copper or a copper alloy on the copper foil. For example, the roughening treatment is preferably carried out according to a plating method that includes at least two plating steps, including a burnt plating step for depositing and adhering fine copper particles on the copper foil, and a cover plating step for preventing the fine copper particles from falling off. In this case, the burnt plating step is carried out by adding carboxybenzotriazole (CBTA) to a copper sulfate solution containing a copper concentration of 5 g / L to 20 g / L and a sulfuric acid concentration of 180 g / L to 240 g / L to a concentration of 20 ppm to 29 ppm, and then applying 14 A / dm ２ 24A / dm or more ２ The cover plating step is preferably performed in a copper sulfate solution containing a copper concentration of 50 g / L to 100 g / L and a sulfuric acid concentration of 200 g / L to 250 g / L at a temperature of 40° C. to 60° C. and at a current of 2 A / dm ２ 4A / dm or more ２ It is preferable to perform electrodeposition as follows. In particular, by adding carboxybenzotriazole within the above concentration range to the plating solution in the burnt plating step, the formation of protruding peaks on the roughened surface can be suppressed while maintaining etching properties similar to those of pure copper, and the roughening particles constituting the roughened surface can be configured to penetrate evenly into the resin, making it easier to form bumps on the treated surface that are suitable for satisfying the above-mentioned surface parameters. Furthermore, by performing electrodeposition at a current density lower than that of conventional methods in the burnt plating step and the cover plating step, it becomes even easier to form bumps on the treated surface that are suitable for satisfying the above-mentioned surface parameters.

[0035] If desired, the roughened copper foil may be subjected to a rust-proofing treatment to form a rust-proofing layer. The rust-proofing treatment preferably includes a zinc plating treatment. The zinc plating treatment may be either a zinc plating treatment or a zinc alloy plating treatment, with a zinc-nickel alloy plating treatment being particularly preferred. The zinc-nickel alloy plating treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, and Co. The Ni / Zn deposition ratio in the zinc-nickel alloy plating is preferably 1.2 to 10, more preferably 2 to 7, and even more preferably 2.7 to 4, by mass. Furthermore, the rust-proofing treatment preferably further includes a chromate treatment, and this chromate treatment is more preferably performed on the surface of the zinc-containing plating after the zinc plating treatment. This can further improve rust prevention. A particularly preferred rust-proofing treatment is a combination of a zinc-nickel alloy plating treatment followed by a chromate treatment.

[0036] 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 can improve moisture resistance, chemical resistance, and adhesion to adhesives, etc. The silane coupling agent layer can be formed by applying an appropriately diluted silane coupling agent and drying it. Examples of the silane coupling agent include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, amino-functional silane coupling agents such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane, mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane, olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane, acrylic-functional silane coupling agents such as 3-methacryloxypropyltrimethoxysilane, imidazole-functional silane coupling agents such as imidazole silane, and triazine-functional silane coupling agents such as triazine silane.

[0037] For the reasons described above, the roughened copper foil preferably further comprises a rust-proofing layer and / or a silane coupling agent layer on the roughened surface, and more preferably comprises both a rust-proofing layer and a silane coupling agent layer. The rust-proofing 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.

[0038] As described above, the roughened copper foil of the present invention may be provided in the form of a carrier-attached copper foil. That is, according to a preferred embodiment of the present invention, a carrier-attached copper foil is provided, which comprises a carrier, a release layer provided on the carrier, and the above-mentioned roughened copper foil provided on the release layer with the roughened surface facing outward. However, the carrier-attached copper foil can have a known layer structure other than the use of the roughened copper foil of the present invention.

[0039] The carrier is a support for supporting the roughened copper foil to improve its handling, and a typical carrier includes a metal layer. Examples of such carriers include aluminum foil, copper foil, stainless steel (SUS) foil, resin film or glass whose surface is metal-coated with copper or the like, and copper foil is preferred. The copper foil may be either rolled copper foil or electrolytic copper foil, but electrolytic copper foil is preferred. The thickness of the carrier is typically 250 μm or less, preferably 9 μm or more and 200 μm or less.

[0040] The surface of the carrier on the release layer side is preferably smooth. That is, in the manufacturing process of the carrier-attached copper foil, an ultrathin copper foil (before roughening treatment) is formed on the surface of the carrier on the release layer side. When the roughened copper foil of the present invention is used in the form of a carrier-attached copper foil, the roughened copper foil can be obtained by roughening such an ultrathin copper foil. Therefore, by smoothing the surface of the carrier on the release layer side, the outer surface of the ultrathin copper foil can also be smoothed, and by roughening the smooth surface of this ultrathin copper foil, it becomes easier to achieve a roughened surface having an interface development area ratio Sdr and core level difference Sk within the above-mentioned predetermined range. To smooth the surface of the carrier on the release layer side, for example, the surface of the cathode used in electrolytic foil production of the carrier can be polished with a buff of a predetermined grit to adjust the surface roughness. That is, the surface profile of the cathode thus adjusted is transferred to the electrode surface of the carrier, and an ultrathin copper foil is formed on the electrode surface of this carrier via a release layer, thereby imparting a smooth surface condition that makes it easy to realize the above-mentioned roughened surface on the outer surface of the ultrathin copper foil. The preferred number of buffs is #2000 or more and #3000 or less, and more preferably #2000 or more and #2500 or less.

[0041] The release layer weakens the carrier peel strength, ensures stability of that strength, and further functions to suppress interdiffusion that may occur between the carrier and copper foil during high-temperature press molding. The release layer is generally formed on one side of the carrier, but may also be formed on both sides. The release layer may be either an organic or inorganic release layer. Examples of organic components used in the organic release layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids, etc. Examples of nitrogen-containing organic compounds include triazole compounds and imidazole compounds, among which triazole compounds are preferred because they tend to stabilize release properties. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N',N'-bis(benzotriazolylmethyl)urea, 1H-1,2,4-triazole, and 3-amino-1H-1,2,4-triazole. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, and 2-benzimidazolethiol. Examples of carboxylic acids include monocarboxylic acids and dicarboxylic acids. On the other hand, examples of inorganic components used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, chromate-treated films, and the like. The release layer can be formed by contacting at least one surface of the carrier with a release layer component-containing solution and fixing the release layer component to the carrier surface. When contacting the carrier with the release layer component-containing solution, this contact can be performed by immersion in the release layer component-containing solution, spraying the release layer component-containing solution, or allowing the release layer component-containing solution to flow down. Other methods for forming a film of the release layer component using a gas phase method such as vapor deposition or sputtering can also be used. Fixing the release layer component to the carrier surface can be performed by adsorption or drying of the release layer component-containing solution, electrodeposition of the release layer component in the release layer component-containing solution, or the like. The thickness of the release layer is typically 1 nm or more and 1 μm or less, preferably 5 nm or more and 500 nm or less.

[0042] If desired, another functional layer may be provided between the release layer and the carrier and / or the roughened copper foil. An example of such another functional layer is an auxiliary metal layer. The auxiliary metal layer is preferably made of nickel and / or cobalt. Forming such an auxiliary metal layer on the surface side of the carrier and / or the surface side of the roughened copper foil can suppress interdiffusion that may occur between the carrier and the roughened copper foil during high-temperature or long-term hot press forming, thereby ensuring stable carrier peel strength. The thickness of the auxiliary metal layer is preferably 0.001 μm or more and 3 μm or less.

[0043] Copper-clad laminate The roughened copper foil of the present invention is preferably used in the production of a copper-clad laminate for printed wiring boards. That is, according to a preferred embodiment of the present invention, a copper-clad laminate comprising the above-mentioned roughened copper foil is provided. By using the roughened copper foil of the present invention, both excellent etching properties and high shear strength can be achieved in the processing of a copper-clad laminate. This copper-clad laminate comprises the roughened copper foil of the present invention and a resin layer provided in close contact with the roughened surface of the roughened copper foil. The roughened copper foil may be provided on one or both sides of the resin layer. The resin layer comprises a resin, preferably an insulating resin. The resin layer is preferably a prepreg and / or a resin sheet. Prepreg is a general term for a composite material in which a substrate such as a synthetic resin plate, glass plate, woven glass fabric, nonwoven glass fabric, or paper is impregnated with a synthetic resin. Preferred examples of insulating resins include epoxy resins, cyanate resins, bismaleimide triazine resins (BT resins), polyphenylene ether resins, and phenolic resins. Examples of insulating resins constituting the resin sheet include insulating resins such as epoxy resins, polyimide resins, and polyester resins. Furthermore, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina to improve insulation. The thickness of the resin layer is not particularly limited, but is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and even more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and / or a resin sheet may be provided on a roughened copper foil via a primer resin layer previously applied to the copper foil surface.

[0044] Printed Wiring Boards The roughened copper foil of the present invention is preferably used in the production of printed wiring boards. That is, according to a preferred embodiment of the present invention, a printed wiring board including the above-mentioned roughened copper foil is provided. By using the roughened copper foil of the present invention, both excellent etching properties and high shear strength can be achieved in the production of printed wiring boards. The printed wiring board according to this embodiment comprises a layer structure in which a resin layer and a copper layer are laminated. The copper layer is a layer derived from the roughened copper foil of the present invention. The resin layer is as described above for the copper-clad laminate. In any case, a known layer structure can be adopted for the printed wiring board, except for the use of the roughened copper foil of the present invention. 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 bonded to one or both sides of a prepreg to form a cured laminate and then a circuit is formed, and multilayer printed wiring boards in which these are multilayered. Other specific examples include flexible printed wiring boards, COFs, TAB tapes, etc. in which a circuit is formed by forming the roughened copper foil of the present invention on a resin film. Further examples include build-up wiring boards in which the roughened copper foil of the present invention is coated with the above-mentioned resin layer to form a resin-coated copper foil (RCC), which is then laminated to the above-mentioned printed circuit board using the resin layer as an insulating adhesive layer, and then the roughened copper foil is used as all or part of the wiring layer to form a circuit using techniques such as modified semi-additive (MSAP) or subtractive methods; build-up wiring boards in which the roughened copper foil is removed and a circuit is formed using a semi-additive method; and direct build-up on wafers in which resin-coated copper foil is alternately laminated and circuit formed on a semiconductor integrated circuit. More advanced examples include antenna elements in which the above-mentioned resin-coated copper foil is laminated to a substrate to form a circuit; electronic materials for panel displays and window glass in which a pattern is formed by laminating the above-mentioned resin-coated copper foil to glass or a resin film via an adhesive layer; and electromagnetic wave shielding films in which a conductive adhesive is applied to the roughened copper foil of the present invention. In particular, the roughened copper foil of the present invention is suitable for the MSAP method. For example, when a circuit is formed by the MSAP method, the configurations shown in FIGS. 1 and 2 can be adopted.

[0045] The present invention is further illustrated by the following examples.

[0046] Examples 1 to 7, 9 and 10 Copper foils with carriers each having a roughened copper foil were prepared and evaluated as follows.

[0047] (1) Preparation of Carrier Using a copper electrolyte solution having the composition shown below, a cathode, and a DSA (dimensionally stable anode) as an anode, a solution temperature of 50°C and a current density of 70 A / dm ２ Electrolysis was performed at 18 μm in thickness to prepare an electrolytic copper foil as a carrier. At this time, an electrode whose surface had been polished with a #2000 buff to adjust the surface roughness was used as the cathode. <Composition of copper electrolyte> - Copper concentration: 80 g / L - Sulfuric acid concentration: 300 g / L - Chlorine concentration: 30 mg / L - Glue concentration: 5 mg / L

[0048] (2) Formation of Release Layer The electrode surface of the pickled carrier was immersed in a carboxybenzotriazole (CBTA) aqueous solution containing 1 g / L of CBTA, 150 g / L of sulfuric acid, and 10 g / L of copper at a liquid temperature of 30° C. for 30 seconds to adsorb the CBTA component onto the electrode surface of the carrier. In this way, a CBTA layer was formed on the electrode surface of the carrier as an organic release layer.

[0049] (3) Formation of auxiliary metal layer The carrier on which the organic release layer was formed was immersed in a solution containing nickel at a concentration of 20 g / L prepared using nickel sulfate, and the solution temperature was 45°C, pH 3, and current density 5 A / dm ２ A deposition amount of nickel equivalent to a thickness of 0.001 μm was deposited on the organic release layer under the conditions of: In this way, a nickel layer was formed as an auxiliary metal layer on the organic release layer.

[0050] (4) Formation of ultra-thin copper foil The carrier on which the auxiliary metal layer was formed was immersed in a copper solution having the composition shown below, and the solution temperature was 50°C and the current density was 5 A / dm ２ 30A / dm or more ２ Electrolysis was performed using the following solution to form an ultra-thin copper foil with a thickness of 1.5 μm on the auxiliary metal layer. <Solution composition> - Copper concentration: 60 g / L - Sulfuric acid concentration: 200 g / L

[0051] (5) Roughening Treatment The surface of the ultrathin copper foil thus formed was subjected to a roughening treatment to form a roughened copper foil, thereby obtaining a carrier-attached copper foil. This roughening treatment consists of a burnt plating process in which fine copper particles are deposited and attached to the ultrathin copper foil, and a cover plating process to prevent the fine copper particles from falling off. In the burnt plating process, carboxybenzotriazole (CBTA) was added at the concentration shown in Table 1 to an acidic copper sulfate solution containing 10 g / L of copper and 200 g / L of sulfuric acid at a solution temperature of 25°C, and the roughening treatment was performed at the current density shown in Table 1. In the subsequent cover plating process, electrodeposition was performed using an acidic copper sulfate solution containing 70 g / L of copper and 240 g / L of sulfuric acid under smooth plating conditions of a solution temperature of 52°C and a current density shown in Table 1. The CBTA concentration and current density in the burnt plating process and the current density in the cover plating process were appropriately changed as shown in Table 1 to produce various samples with different roughened surface characteristics.

[0052] (6) Rust prevention treatment The roughened surface of the obtained carrier-attached copper foil was subjected to rust prevention treatment consisting of zinc-nickel alloy plating treatment and chromate treatment. First, a solution containing 1 g / L of zinc, 2 g / L of nickel, and 80 g / L of potassium pyrophosphate was used, and the solution temperature was 40°C, and the current density was 0.5 A / dm ２ Then, a zinc-nickel alloy plating treatment was carried out on the roughened layer and the surface of the carrier under the conditions of: pH 12, current density 1 A / dm ２ The zinc-nickel alloy plated surface was then subjected to a chromate treatment under the conditions described above.

[0053] (7) Silane Coupling Agent Treatment A commercially available aqueous solution containing a silane coupling agent was adsorbed onto the surface of the carrier-attached copper foil on the side of the roughened copper foil, and the water was evaporated using an electric heater to perform the silane coupling agent treatment. At this time, the silane coupling agent treatment was not performed on the carrier side.

[0054] (8) Evaluation The carrier-attached copper foil thus obtained was evaluated for various properties as follows.

[0055] (8a) Surface Property Parameters of Roughened Surface The roughened surface of the roughened copper foil was measured by surface roughness analysis using a laser microscope (OLS5000, manufactured by Olympus Corporation) in accordance with ISO 25178. Specifically, the surface roughness of the roughened copper foil was measured based on an area of ​​16384 μm ２ The surface profile of the region was measured using the laser microscope with a 100x magnification lens with a numerical aperture (N.A.) of 0.95. After noise removal and linear surface tilt correction for the obtained surface profile of the roughened surface, surface texture analysis was performed to measure the maximum height Sz, the interface developed area ratio Sdr, the surface texture aspect ratio Str, the core level difference Sk, and the peak density Spd. In this case, Sz, Sdr, Str, and Sk were measured using an S filter with a cutoff wavelength of 0.55 μm and an L filter with a cutoff wavelength of 10 μm. Meanwhile, Spd was measured using an S filter with a cutoff wavelength of 3 μm and an L filter with a cutoff wavelength of 10 μm. The results are shown in Table 1.

[0056] (8b) Circuit Formability (Etching Property Evaluation) A laminate for evaluation was produced using the obtained carrier-attached copper foil. That is, as shown in FIG. 5, a roughened copper foil 110 of a carrier-attached copper foil was laminated on the surface of an insulating resin substrate 111 via a prepreg 112 (manufactured by Mitsubishi Gas Chemical Company, Inc., GHPL-830NSF, thickness 0.1 mm), and then thermocompression-bonded at a pressure of 4.0 MPa and a temperature of 220 ° C. for 90 minutes. The carrier (not shown) was then peeled off to obtain a copper-clad laminate as an evaluation laminate 114. In the example shown in FIG. 5, the roughened copper foil 110 has roughening particles 110a on its surface. Note that the etching amount required for etching property evaluation varies depending on the thickness of the ultra-thin copper foil. For this reason, as shown in FIG. 5 , the thickness of the evaluation laminate 114 was reduced by half etching or increased by copper sulfate plating as needed so that the thickness of the roughened copper foil 110 in the evaluation laminate 114 was equivalent to 1.5 μm (excluding the thickness of the roughening particles 110a). The evaluation laminate 114, in which the thickness of the roughened copper foil 110 was adjusted to 1.5 μm, was etched in 0.1 μm increments using a sulfuric acid-hydrogen peroxide-based etching solution, and the amount (depth) until the copper (including the roughening particles 110a) on the surface was completely removed was measured. The measurement was performed by checking with an optical microscope (500x magnification). More specifically, the presence or absence of copper was confirmed with an optical microscope every time 0.1 μm of etching was repeated, and the value (μm) obtained by multiplying (the number of etchings) by 0.1 μm was used as an indicator of etching property. For example, an etching rate of 2.5 μm means that after 25 0.1 μm etchings, no residual copper can be detected under an optical microscope (i.e., 0.1 μm x 25 times = 2.5 μm). In other words, the smaller this value, the more copper on the surface can be removed with fewer etchings. In other words, the smaller this value, the better the etching rate. The measured etching amount was rated and evaluated according to the following criteria, and a sample was deemed to have passed if it was rated A to C. The results are shown in Table 1.<Etching property evaluation criteria> - Evaluation A: The required etching amount is 2.3 μm or less. - Evaluation B: The required etching amount is more than 2.3 μm and 2.5 μm or less. - Evaluation C: The required etching amount is more than 2.5 μm and 2.7 μm or less. - Evaluation D: The required etching amount is more than 2.7 μm.

[0057] (8c) Plating Circuit Adhesion (Shear Strength) A dry film was attached to the above-described evaluation laminate, followed by exposure and development. A 14 μm thick copper layer was deposited by pattern plating on the laminate masked with the developed dry film, and the dry film was then peeled off. The exposed copper portions were etched using a sulfuric acid-hydrogen peroxide-based etching solution to produce a circuit sample for shear strength measurement (laminate 134 on which circuit 136 shown in FIG. 6 was formed) measuring 15 μm in height, 10 μm in width, and 200 μm in length. Using a bond strength tester (4000Plus Bondtester, manufactured by Nordson DAGE), the shear strength was measured when the circuit 136 was pushed from the side of the circuit sample for shear strength measurement. That is, as shown in FIG. 6 , the laminate 134 on which the circuit 136 was formed was placed on a movable stage 132, and the stage 132 was moved in the direction of the arrow in the figure. The circuit 136 was pressed against a pre-fixed detector 138, applying a lateral force to the side of the circuit 136 and shifting the circuit 136 laterally. The force (gf) at that time was measured by the detector 138 and used as the shear strength. The test type was a destructive test, and measurements were performed under the following conditions: test height 5 μm, descent speed 0.050 mm / s, test speed 200 μm / s, tool travel distance 0.05 mm, and fracture recognition point 10%. The obtained shear strength was graded and evaluated according to the following criteria, and a grade of A to C was determined to be acceptable. The results are shown in Table 1. <Shear strength evaluation criteria> - Evaluation A: Shear strength of 13.50 gf or more - Evaluation B: Shear strength of 12.50 gf or more and less than 13.50 gf - Evaluation C: Shear strength of 12.00 gf or more and less than 12.50 gf - Evaluation D: Shear strength less than 12.00 gf

[0058] Example 8 (Comparative) A carrier-attached copper foil was produced and evaluated in the same manner as in Example 1, except for the following a) to c). The results are shown in Table 1. a) The carrier was prepared according to the procedure shown below. b) A release layer, an auxiliary metal layer, and an ultra-thin copper foil were formed in this order on the deposition surface of the carrier instead of on the electrode surface of the carrier. c) Instead of the burnt plating process and the cover plating process, the ultra-thin copper foil was roughened by the black plating process shown below.

[0059] (Preparation of Carrier) A sulfuric acid acid copper sulfate solution having the composition shown below was used as the copper electrolyte, a titanium electrode having a surface roughness Ra of 0.20 μm was used as the cathode, and a DSA (dimensionally stable anode) was used as the anode. The solution temperature was 45° C., and the current density was 55 A / dm ２ The solution was electrolyzed with a solution of 80 g / L of copper sulfate, and a 12 μm thick electrolytic copper foil was obtained as a carrier. <Composition of sulfuric acid acid copper sulfate solution> - Copper concentration: 80 g / L - Sulfuric acid concentration: 140 g / L - Bis(3-sulfopropyl)disulfide concentration: 30 mg / L - Diallyldimethylammonium chloride polymer concentration: 50 mg / L - Chlorine concentration: 40 mg / L

[0060] (Black plating process) The surface of the ultra-thin copper foil was plated with a black roughening copper electrolytic solution having the following composition at a solution temperature of 30°C and a current density of 50 A / dm ２ The copper electrolytic solution for black roughening was electrolyzed under the conditions of 13 g / L, 1000 kJ / min ...

[0061]

Claims

1. A roughened copper foil having a roughened surface on at least one side, wherein the roughened surface has an interface developed area ratio Sdr of 3.50% or more and 12.00% or less, as measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter, and a core level difference Sk of 0.15 μm or more and 0.35 μm or less, as measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter.

2. A roughened copper foil as described in claim 1, in which the ratio of the level difference Sk (μm) of the core portion to the developed area ratio Sdr (%) of the interface, Sk / Sdr, is 0.038 or more and 0.050 or less.

3. The roughened surface of the copper foil according to claim 1 or 2, wherein the product Sz × Sk of the maximum height Sz (μm) and the level difference Sk (μm) of the core portion measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm using an S filter and a cutoff wavelength of 10 μm using an L filter is 0.25 or more and 0.50 or less.

4. A roughened copper foil according to any one of claims 1 to 3, wherein the developed area ratio Sdr of the interface is 4.50% or more and 8.50% or less.

5. The roughened surface has a peak density (Spd) of 2.00×10 measured under conditions of an S filter cutoff wavelength of 3.0 μm and an L filter cutoff wavelength of 10 μm in accordance with ISO 25178. ４ mm －２ Above 3.00 x 10 ４ mm －２ The roughened copper foil according to any one of claims 1 to 4, wherein:

6. The roughened copper foil according to any one of claims 1 to 5, wherein the roughened surface has an aspect ratio Str of 0.2 to 0.5 in terms of surface properties measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm using an S filter and a cutoff wavelength of 10 μm using an L filter.

7. The roughened copper foil according to any one of claims 1 to 6, wherein the roughened surface has a maximum height Sz of 1.6 μm or less, measured in accordance with ISO 25178 under conditions of a cutoff wavelength of 0.55 μm using an S filter and a cutoff wavelength of 10 μm using an L filter.

8. The roughened copper foil according to any one of claims 1 to 7, further comprising an anticorrosive layer and / or a silane coupling agent layer on the roughened surface.

9. A copper foil with a carrier comprising a carrier, a release layer provided on the carrier, and the roughened copper foil according to any one of claims 1 to 8 provided on the release layer with the roughened surface facing outward.

10. A copper-clad laminate comprising the roughened copper foil according to any one of claims 1 to 8.

11. A printed wiring board comprising the roughened copper foil according to any one of claims 1 to 8.