WO2021157362A1 - Roughened copper foil, carrier-attached copper foil, copper clad laminate plate, and printed wiring board - Google Patents

Abstract

Provided is a roughened copper foil which can achieve both of excellent etching properties and high share strength in the processing of a copper clad laminate plate or the manufacture of a printed wiring board. The roughened copper foil has a roughened surface on at least one side thereof. In the roughened surface, the interface developed area ratio Sdr is 3.50% to 12.00% inclusive as measured in accordance with ISO25178 under the conditions including an S filter cut-off wavelength of 0.55 μm and an L filter cut-off wavelength of 10 μm. In the roughened copper foil, the core part level difference Sk is 0.15 μm to 0.35 μm inclusive as measured in accordance with ISO25178 under the conditions including an S filter cut-off wavelength of 0.55 μm and an L filter cut-off wavelength of 10 μm.

Description

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

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

In recent years, the MSAP (Modified Semi-Additive Process) method has been widely adopted as a manufacturing method for printed wiring boards suitable for circuit miniaturization. The MSAP method is a method suitable for forming an extremely fine circuit, and is performed using a copper foil with a carrier in order to take advantage of its characteristics. For example, as shown in FIGS. 1 and 2, the ultrathin copper foil 10 is pressed and adhered to the insulating resin substrate 11 provided with the lower layer circuit 11b on the base material 11a by using the prepreg 12 and the primer layer 13. (Step (a)), the carrier (not shown) is peeled off, and then a via hole 14 is formed by laser perforation if necessary (step (b)). Next, after the chemical copper plating 15 is applied (step (c)), masking is performed in a predetermined pattern by exposure and development using the dry film 16 (step (d)), and the electrolytic copper plating 17 is applied (step (e). )). After removing the dry film 16 to form the wiring portion 17a (step (f)), unnecessary ultrathin copper foil and the like between the wiring portions 17a and 17a adjacent to each other are removed by etching over their entire thickness (step (f)). Step (g)), a wiring 18 formed in a predetermined pattern is obtained. Here, in order to improve the physical adhesion between the circuit and the substrate, it is common practice to roughen the surface of the ultrathin copper foil 10.

As a copper foil subjected to such a roughening treatment, for example, in Patent Document 1 (Patent No. 6462961), a roughening treatment layer, a rust prevention treatment layer and a silane coupling layer are provided on at least one surface of the copper foil. Surface-treated copper foils laminated in this order are disclosed. Patent Document 1 describes the development area ratio Sdr of the interface measured from the surface of the silane coupling layer of the surface-treated copper foil for the purpose of producing a printed wiring board having low transmission loss and excellent reflow heat resistance. It is also disclosed that 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.

In fact, some copper foils with carriers that are excellent in fine circuit formation by the MSAP method and the like have been proposed. For example, in Patent Document 2 (International Publication No. 2016/117587), the average distance between surface peaks on the surface on the release layer side is 20 μm or less, and the maximum height difference of the waviness on the surface opposite to the release layer is. A copper foil with a carrier provided with an ultrathin copper foil having a thickness of 1.0 μm or less is disclosed, and according to such an embodiment, it is said that both fine circuit formability and laser processability can be achieved at the same time. Further, in Patent Document 3 (Japanese Unexamined Patent Publication No. 2018-26590), the maximum mountain height Sp and the protruding mountain height according to ISO25178 on the surface on the ultrathin copper layer side are described for the purpose of improving the fine circuit formability. A copper foil with a carrier having a Sp / Spk ratio of 3.271 or more and 10.739 or less with Spk is disclosed.

Japanese Patent No. 6462961 International Publication No. 2016/1157587 Japanese Unexamined Patent Publication No. 2018-26590

In recent years, in order to form a finer circuit by the above-mentioned MSAP method or the like, further smoothing and miniaturization of coarsened particles are required for copper foil. However, by smoothing the copper foil and miniaturizing the coarsened particles, the etching property of the copper foil, which is related to the miniaturization of the circuit, is improved, but the physical adhesion between the copper foil and the substrate resin or the like is lowered. .. In particular, as the thinning of the circuit progresses, in the process of mounting the printed wiring board, physical stress from the lateral direction (that is, shear stress) is applied to the circuit, so that the circuit is easily peeled off and the yield is lowered. It has become apparent. In this respect, one of the physical adhesion indexes between the circuit and the substrate is the shear strength, and in order to effectively avoid the above-mentioned circuit peeling, it is required to keep the shear strength above a certain level. However, in order to secure a share strength of a certain level or higher, the roughened particles of the copper foil must be enlarged, and there is a problem that it is difficult to achieve both etching properties.

The present inventors have recently applied a surface profile in a roughened copper foil in which the developed area ratio Sdr of the interface and the level difference Sk of the core portion defined in ISO25178 are controlled within predetermined ranges, respectively. It was found that excellent etching properties and high area strength can be achieved at the same time in the processing of stretched laminated boards or the manufacture of printed wiring boards.

Therefore, an object of the present invention is to provide a roughened copper foil capable of achieving both excellent etching properties and high market share strength in the processing of copper-clad laminates or the production of printed wiring boards.

According to one aspect of the present invention, a roughened copper foil having a roughened surface on at least one side.
The roughened surface has an interface development area ratio Sdr of 3.50% or more and 12.00 measured under the conditions of a cutoff wavelength of 0.55 μm by the S filter and a cutoff wavelength of 10 μm by the L filter in accordance with ISO25178. % Or less, and the level difference Sk of the core portion measured under the conditions of a cutoff wavelength of 0.55 μm by the S filter and a cutoff wavelength of 10 μm by the L filter in accordance with ISO25178 is 0.15 μm or more and 0.35 μm or less. , Roughened copper foil is provided.

According to another aspect of the present invention, the carrier, the release layer provided on the carrier, and the roughened copper foil provided on the release layer with the roughened surface facing outward are provided. A copper foil with a carrier is provided.

According to still another aspect of the present invention, a copper-clad laminate provided with the roughened copper foil is provided.

According to still another aspect of the present invention, a printed wiring board provided with the roughened copper foil is provided.

It is a process flow diagram for demonstrating the MSAP method, and is the figure which shows the process (step (a)-(d)) of the first half. It is a process flow diagram for demonstrating the MSAP method, and is the figure which shows the process (process (e)-(g)) of the latter half. It is a figure for demonstrating the load curve and the load area ratio determined in accordance with ISO25178. The figure for explaining the load area ratio Smr1 for separating the protruding peak portion and the core portion, the load area ratio Smr2 for separating the protruding valley portion and the core portion, and the level difference Sk of the core portion determined in accordance with ISO25178. be. It is a schematic cross-sectional view which shows an example of the laminated body for evaluation just before performing etching in circuit formability (etchability evaluation). It is a schematic diagram for demonstrating the measuring method of the share strength.

Definitions Definitions of terms or parameters used to identify the present invention are shown below.

In the present specification, the “interface development area ratio Sdr” indicates how much the development area (surface area) of the definition region, which is measured in accordance with ISO25178, is increased with respect to the area of the definition region. It is a parameter. In this specification, the developed area ratio Sdr of the interface is expressed as an increase (%) in the surface area. The smaller this value is, the more flat the surface is, and the Sdr of the completely flat surface is 0%. On the other hand, the larger this value is, the more uneven the surface shape is. For example, a surface Sdr of 40% indicates that the surface has a 40% increase in surface area from a perfectly flat surface.

In the present specification, the "surface load curve" (hereinafter, simply referred to as "load curve") is a curve representing the height at which the load area ratio is 0% to 100%, which is measured in accordance with ISO25178. say. As shown in FIG. 3, the load area ratio is a parameter representing the area of a region having a certain height c or more. The load area ratio at height c corresponds to Smr (c) in FIG. As shown in FIG. 4, the secant line of the load curve drawn from the load area ratio of 0% along the load curve with the difference of the load area ratio set to 40% is moved from the load area ratio of 0%, and the secant line is used. The position where the slope is the gentlest is called the central part of the load curve. The straight line that minimizes the sum of squares of the deviations in the vertical axis direction with respect to this central portion is called an equivalent straight line. The portion included in the height range of the load area ratio of the equivalent straight line from 0% to 100% is called the core portion. The part higher than the core part is called the protruding peak part, and the part lower than the core part is called the protruding valley part.

In the present specification, the “core level difference Sk” is a value obtained by subtracting the minimum height from the maximum height of the core portion measured in accordance with ISO25178, and as shown in FIG. It is a parameter calculated by the difference in height between 0% and 100% of the load area ratio of the equivalent straight line.

In the present specification, the "maximum height Sz" is a parameter representing the distance from the highest point to the lowest point on the surface, which is measured in accordance with ISO25178.

In the present specification, the "surface texture aspect ratio Str" is a parameter representing the isotropic or anisotropy of the surface texture, which is measured in accordance with ISO25178. Str ranges from 0 to 1, and usually shows strong isotropic when Str> 0.5, and conversely shows strong anisotropy when Str <0.3.

In the present specification, the “peak peak density Spd” is a parameter representing the number of peak peaks per unit area measured in accordance with ISO25178, and is a peak peak larger than 5% of the maximum amplitude in the contour curved surface. Only points shall be counted. A large value suggests that the number of contact points with other objects is large.

The interface development area ratio Sdr, the core level difference Sk, the maximum height Sz, the surface aspect ratio Str, and the peak density Spd of the peaks are two-dimensional regions ^{of a predetermined measurement area (for example, 16384 μm 2) on the roughened surface.} ) Can be calculated by measuring the surface profile with a commercially available laser microscope. In the present specification, each numerical value 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 is the cutoff wavelength of 0.55 μm by the S filter and the cutoff by the L filter. The value shall be measured under the condition of a wavelength of 10 μm. Further, in the present specification, the numerical value of the peak density Spd of the peak is a value measured under the conditions of a cutoff wavelength of 3 μm by the S filter and a cutoff wavelength of 10 μm by the L filter.

In the present specification, the "electrode surface" of the carrier refers to the surface on the side that was in contact with the cathode when the carrier was manufactured.

In the present specification, the "precipitation surface" of the carrier refers to the surface on which electrolytic copper is deposited during carrier production, that is, the surface on the side that is not in contact with the cathode.

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. On this roughened surface, the developed area ratio Sdr of the interface is 3.50% or more and 12.00% or less, and the level difference Sk of the core portion is 0.15 μm or more and 0.35 μm or less. In this way, in the roughened copper foil, by imparting a surface profile in which the development area ratio Sdr of the interface and the level difference Sk of the core portion are controlled within predetermined ranges, the copper-clad laminate is processed or the printed wiring board is provided. It is possible to achieve both excellent etching properties and high share strength in the production of.

Originally, it is difficult to achieve both excellent etching properties and high market share strength. As described above, in order to improve the etching property of the copper foil, it is generally required to reduce the roughened particles, while in order to increase the share strength of the circuit, the roughened particles are generally required. This is because it is required to increase the size. In particular, the shear strength is not simply proportional to the specific surface area, roughening height, etc., which have been conventionally used for evaluation, and it has been difficult to control them. In this regard, it is effective for the present inventors to perform evaluation by combining the developed area ratio Sdr of the interface and the level difference Sk of the core portion in order to obtain a correlation with physical properties such as etching property and shear strength. Was found. Then, by controlling each of these surface parameters within the above-mentioned predetermined range, roughening having a bump height and a specific surface area that is convenient for ensuring high shear strength while being a fine surface having excellent etching properties. We have found that treated copper foil can be obtained. As described above, according to the roughened copper foil of the present invention, excellent etching property and high share strength can be realized, and therefore, high circuit adhesion from the viewpoint of excellent fine circuit formability and share strength can be realized. It is possible to achieve both sex and sex. Conventionally, there are known techniques for controlling the developed area ratio Sdr, the root mean square surface gradient Sdq, and the aspect ratio Str of the surface texture on the surface of the surface-treated copper foil (see Patent Document 1 described above). However, all of these parameters are parameters that are obtained including the protruding ridges, and if the occurrence of the protruding ridges is suppressed, the values may become too small. On the other hand, the present inventors roughened by controlling the level difference Sk of the core portion, which is a parameter not including the protruding peak portion, and the developing area ratio Sdr, which is a parameter including the protruding peak portion. With respect to the treated surface, the generation of protruding peaks can be suppressed, and each roughened particle constituting the roughened treated surface can be configured to bite into the resin on average, whereby fine particles having excellent etching properties can be formed. It has been found that a roughened copper foil having a bump height and a specific surface area that is convenient for ensuring a high shear strength while being a surface can be obtained.

From the viewpoint of achieving excellent etching properties and high share strength in a well-balanced manner, the roughened copper foil preferably has an interface development area ratio Sdr of 3.50% or more and 12.00% or less on the roughened surface. It is 4.50% or more and 8.50% or less, more preferably 4.50% or more and 6.00% or less. Within such a range, a sufficient adhesive area with the resin laminated at the time of manufacturing a copper-clad laminate or a printed wiring board is secured, even though the surface has a fine surface (roughening height) with excellent etching properties. This can improve the circuit adhesion from the viewpoint of share strength.

From the viewpoint of achieving excellent etching properties and high shear strength in a well-balanced manner, the roughened copper foil has a core level difference Sk of 0.15 μm or more and 0.35 μm or less on the roughened surface, preferably 0. It is 23 μm or more and 0.35 μm or less, more preferably 0.25 μm or more and 0.35 μm or less. Within such a range, even though the surface has a fine surface (roughening height) having excellent etching properties, the roughened particles constituting the roughened surface can bite into the resin on average. , Adhesion with resin is improved. That is, if there is unevenness in the roughening treatment, it is considered that the unevenness becomes a protruding peak on the roughening treatment surface. However, such unevenness (protruding mountain portion) does not easily contribute to the improvement of circuit adhesion from the viewpoint of share strength. In this respect, the maximum height Sz and the like used in the conventional evaluation are parameters including the protruding peaks. Therefore, when trying to improve the circuit adhesion based on such a parameter, the roughening height tends to be large, and therefore the etching property tends to be lowered. On the other hand, the level difference Sk of the core portion is a parameter that does not include the protruding peak portion 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 optimum surface shape for improving the adhesion with the resin, and as a result, the increase in the roughening height can be suppressed. Is also possible.

The roughened copper foil has a Sk / Sdr of 0.038 or more and 0.050 or less, which is the ratio of the level difference Sk (μm) of the core portion to the developed area ratio Sdr (%) of the interface on the roughened surface. Is preferable, and more preferably 0.045 or more and 0.050 or less. Within such a range, the uneven shape of the roughened surface has less unevenness in height, and not only the uneven shape of the roughened surface is large (that is, the surface area is large), but also the core. The height of the part can also be sufficiently secured. That is, the level difference Sk of the core portion is a parameter obtained by excluding the protruding peak portion, while the developed area ratio Sdr is a parameter obtained including the protruding peak portion. Therefore, when the number of protruding peaks increases or decreases, the value of the level difference Sk of the core portion is constant, but the value of the developed area ratio Sdr changes. Therefore, by controlling the ratio of the level difference Sk of the core portion and the developed area ratio Sdr within the above range, it is possible to suppress the occurrence of protruding peaks on the roughened surface. It is possible to make it easy for each roughened particle constituting the roughened surface to bite into the resin on average. As a result, excellent etching properties and high share strength can be realized in a more balanced manner.

The roughened copper foil preferably has Sz × Sk, which is the product of the maximum height Sz (μm) on the roughened surface and the level difference Sk (μm) of the core portion, of 0.25 or more and 0.50 or less. , More preferably 0.36 or more and 0.50 or less. Within such a range, the uneven shape of the roughened surface is more suitable to suppress the occurrence of protruding peaks, and to realize excellent etching property and high share strength in a well-balanced manner. Become. Further, from the viewpoint of realizing a fine surface having more excellent etching property, 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. It is 1.4 μm or more, more preferably 1.0 μm or more and 1.2 μm or less.

The roughened copper foil preferably has a peak density Spd of 2.00 × 10 ⁴ mm ^-2 or more and 3.00 × 10 ⁴ mm ^-2 or less on the roughened surface, more preferably 2.20. It is × 10 ⁴ mm ⁻² or more and 3.00 × 10 ⁴ mm − ² or less, more preferably 2.75 × 10 ⁴ mm − ² or more and 2.85 × 10 ⁴ mm − ² or less. By doing so, it is possible to secure a sufficient adhesion point with the resin laminated at the time of manufacturing the copper-clad laminate or the printed wiring board, and it is possible to more effectively improve the circuit adhesion from the viewpoint of the share strength. can.

The roughened copper foil preferably has an aspect ratio Str of the surface texture on the roughened surface of 0.2 or more and 0.5 or less, more preferably 0.24 or more and 0.50 or less, and further preferably 0. It is 45 or more and 0.50 or less. Within such a range, there will be undulations on the roughened surface that are convenient for adhesion to the resin. As a result, it is possible to more effectively improve the circuit adhesion from the viewpoint of share strength, even though the surface is fine with excellent etching properties.

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 further preferably 1.0 μm or more and 3.0 μm or less. The roughened copper foil is not limited to the one obtained by roughening the surface of a normal copper foil, and may be a roughened copper foil surface of a copper foil with a carrier. Here, the thickness of the roughened copper foil does not include the height of the roughened particles formed on the surface of the roughened surface (the thickness of the copper foil itself constituting the roughened copper foil). Is. A copper foil having a thickness in the above range may be referred to as an ultrathin copper foil.

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 roughened surfaces on only one side. The roughened surface is typically provided with a plurality of roughened particles (humps), and it is preferable that each of the plurality of roughened particles is made of copper particles. The copper particles may be made of metallic copper or may be made of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably performed by forming roughened particles with copper or a copper alloy on the copper foil. For example, roughening treatment is performed according to a plating method that goes through at least two types of plating steps, including a burn-plating step of depositing and adhering fine copper particles on a copper foil and a covering plating step for preventing the fine copper grains from falling off. Is preferably performed. In this case, in the burn-plating step, carboxybenzotriazole (CBTA) is added to a copper sulfate solution containing a copper concentration of 5 g / L or more and 20 g / L or less and a sulfuric acid concentration of 180 g / L or more and 240 g / L or less to a concentration of 20 ppm or more and 29 ppm or less. It was added as a temperature of 15 ℃ above 35 ° C. or less, preferably performed 14A / dm ² or more 24A / dm ² hands electrodeposition below. The cover plating step is performed in a copper sulfate solution containing a copper concentration of 50 g / L or more and 100 g / L or less and a sulfuric acid concentration of 200 g / L or more and 250 g / L or less at a temperature of 40 ° C. or more and 60 ° C. or less at 2 A / dm ² or more. It is preferable to carry out electrodeposition at 4 A / dm ^{2 or less.} In particular, in the burn-plating step, by adding carboxybenzotriazole within the above concentration range to the plating solution, the occurrence of protruding peaks is suppressed on the roughened surface while maintaining the etching property close to that of pure copper. The roughened particles constituting the roughened surface can be configured to bite into the resin on average, and it becomes easy to form bumps on the treated surface that are convenient for satisfying the above-mentioned surface parameters. Further, in the burn-plating step and the cover-plating step, by performing electrodeposition with a lower current density than in the conventional method, it becomes easier to form more convenient bumps on the treated surface in order to satisfy the above-mentioned surface parameters.

If desired, the roughened copper foil may be subjected to a rust preventive treatment to form a rust preventive treatment layer. The rust preventive treatment preferably includes a plating treatment using zinc. The plating treatment using zinc may be either a zinc plating treatment or a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, and Co. The Ni / Zn adhesion ratio in the zinc-nickel alloy plating 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 mass ratio. Further, the rust preventive treatment preferably further includes a chromate treatment, and it is more preferable that the chromate treatment is performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust prevention property can be further improved. A particularly preferable rust preventive treatment is a combination of a zinc-nickel alloy plating treatment and a subsequent chromate treatment.

If desired, the surface of the roughened copper foil may be treated with a silane coupling agent to form a silane coupling agent layer. As a result, moisture resistance, chemical resistance, adhesion to an adhesive or the like can be improved. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, applying it, and drying it. Examples of silane coupling agents include epoxy functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltrimethoxysilane, N- (2- (2-). Aminoethyl) -3-aminopropyltrimethoxysilane, N-3- (4- (3-aminopropoxy) butoxy) propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. Amino-functional silane coupling agent, or mercapto-functional silane coupling agent such as 3-mercaptopropyltrimethoxysilane, or olefin-functional silane coupling agent such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane, or 3-methacry. Examples thereof include acrylic functional silane coupling agents such as loxypropyltrimethoxysilane, imidazole functional silane coupling agents such as imidazole silane, and triazine functional silane coupling agents such as triazinesilane.

For the reasons described above, the roughened copper foil preferably further includes a rust preventive treatment layer and / or a silane coupling agent layer on the roughened surface, and more preferably the rust preventive treatment layer and the silane coupling agent layer. It has both. 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 Foil with Carrier As described above, the roughened copper foil of the present invention may be provided in the form of a copper foil with a carrier. That is, according to a preferred embodiment of the present invention, the carrier, the release layer provided on the carrier, and the roughening-treated copper foil provided on the release layer with the roughening-treated surface facing outward are provided. Copper foil with a carrier is provided. However, as the copper foil with a carrier, a known layer structure can be adopted except that the roughened copper foil of the present invention is used.

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

It is preferable that the surface of the carrier on the release layer side is smooth. That is, in the process of manufacturing a copper foil with a carrier, 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 copper foil with a carrier, the roughened copper foil can be obtained by subjecting such an ultrathin copper foil to a roughening treatment. 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 applying a roughening treatment to the smooth surface of the ultrathin copper foil, the surface can be roughened. It becomes easy to realize a roughened surface having a developed area ratio Sdr of the interface within the predetermined range and a level difference Sk of the core portion. The surface of the carrier on the release layer side can be smoothed, for example, by polishing the surface of the cathode used for electrolytic foil forming of the carrier with a buff having a predetermined count 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 the ultrathin copper foil is formed on the electrode surface of the carrier via the release layer, whereby the outer surface of the ultrathin copper foil is formed. It is possible to impart a smooth surface state that facilitates the realization of the roughened surface described above. The preferred buff count is # 2000 or more and # 3000 or less, and more preferably # 2000 or more and # 2500 or less.

The peeling layer is a layer having a function of weakening the peeling strength of the carrier, ensuring the stability of the strength, and further suppressing the mutual diffusion that may occur between the carrier and the copper foil during press molding at a high temperature. .. The release layer is generally formed on one surface of the carrier, but may be formed on both sides. The release layer may be either an organic release layer or an inorganic release layer. Examples of the organic component used in the organic exfoliation layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, and carboxylic acids. Examples of the nitrogen-containing organic compound include a triazole compound and an imidazole compound, and among them, the triazole compound is preferable because the peelability is easily stable. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N', N'-bis (benzotriazolylmethyl) urea, 1H-1,2,4-triazole and 3-amino-. Examples thereof include 1H-1,2,4-triazole and the like. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiothianulic acid, 2-benzimidazole thiol and the like. Examples of carboxylic acids include monocarboxylic acids, dicarboxylic acids and the like. On the other hand, examples of the inorganic component used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and a chromate-treated film. The release layer may be formed by bringing the release layer component-containing solution into contact with at least one surface of the carrier and fixing the release layer component to the surface of the carrier. When the carrier is brought into contact with the release layer component-containing solution, this contact may be performed by immersion in the release layer component-containing solution, spraying the release layer component-containing solution, flowing down the release layer component-containing solution, or the like. In addition, a method of forming a film of the release layer component by a vapor phase method such as thin film deposition or sputtering can also be adopted. Further, the release layer component may be fixed to the carrier surface 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.

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. By forming such an auxiliary metal layer on the surface side of the carrier and / or on the surface side of the roughened copper foil, it may occur between the carrier and the roughened copper foil during hot press molding at a high temperature or for a long time. Mutual diffusion can be suppressed and the stability of the peeling strength of the carrier can be ensured. The thickness of the auxiliary metal layer is preferably 0.001 μm or more and 3 μm or less.

Copper-clad laminate The roughened copper foil of the present invention is preferably used for producing copper-clad laminates for printed wiring boards. That is, according to a preferred embodiment of the present invention, a copper-clad laminate provided with the roughened copper foil is provided. By using the roughened copper foil of the present invention, it is possible to achieve both excellent etching properties and high market share strength in the processing of copper-clad laminates. This copper-clad laminate comprises the roughened copper foil of the present invention and a resin layer provided in close contact with the roughened surface of the roughened copper foil. The roughened copper foil may be provided on one side of the resin layer or may be provided on both sides. The resin layer contains a resin, preferably an insulating resin. The resin layer is preferably a prepreg and / or a resin sheet. Prepreg is a general term for composite materials in which a base material such as a synthetic resin plate, a glass plate, a glass woven fabric, a glass non-woven fabric, or paper is impregnated with a synthetic resin. Preferred examples of the insulating resin include epoxy resin, cyanate resin, bismaleimide triazine resin (BT resin), polyphenylene ether resin, phenol resin and the like. Further, examples of the insulating resin constituting the resin sheet include insulating resins such as epoxy resin, polyimide resin, and polyester resin. Further, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving the insulating property. 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. A resin layer such as a prepreg and / or a resin sheet may be provided on the roughened copper foil via a primer resin layer previously applied to the surface of the copper foil.

Printed Wiring Board The roughened copper foil of the present invention is preferably used for producing a printed wiring board. That is, according to a preferred embodiment of the present invention, a printed wiring board provided with the roughened copper foil is provided. By using the roughened copper foil of the present invention, it is possible to achieve both excellent etching properties and high market share strength in the production of a printed wiring board. The printed wiring board according to this embodiment includes a layer structure in which a resin layer and a copper layer are laminated. The copper layer is a layer derived from the roughened copper foil of the present invention. The resin layer is as described above for the copper-clad laminate. In any case, the printed wiring board can adopt a known layer structure except that the roughened copper foil of the present invention is used. Specific examples of the printed wiring board include a single-sided or double-sided printed wiring board in which a circuit is formed by adhering the roughened copper foil of the present invention to one or both sides of a prepreg to form a cured laminate, or a multilayer of these. Examples include a multi-layer printed wiring board. Further, as another specific example, a flexible printed wiring board, COF, TAB tape, etc., in which the roughened copper foil of the present invention is formed on a resin film to form a circuit can be mentioned. As yet another specific example, a copper foil with resin (RCC) obtained by applying the above-mentioned resin layer to the roughened copper foil of the present invention was formed, and the resin layer was laminated on the above-mentioned printed circuit board as an insulating adhesive layer. After that, the roughened copper foil is used as the whole or part of the wiring layer, and the build-up wiring board in which the circuit is formed by the modified semi-additive (MSAP) method, the subtractive method, etc., and the roughened copper foil are removed. Examples thereof include a build-up wiring board in which a circuit is formed by a semi-additive method, and a direct build-up on wafer in which a copper foil with a resin is laminated and a circuit is formed alternately on a semiconductor integrated circuit. As a more advanced specific example, an antenna element formed by laminating the above-mentioned copper foil with resin on a base material and forming a circuit, an electronic material for a panel display or a window formed by laminating a pattern on glass or a resin film via an adhesive layer. Examples thereof include electronic materials for glass, electromagnetic wave shield films obtained by applying a conductive adhesive 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 the circuit is formed by the MSAP method, the configuration shown in FIGS. 1 and 2 can be adopted.

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

Examples 1-7, 9 and 10
A copper foil with a carrier provided with a roughened copper foil was prepared and evaluated as follows.

(1) Preparation of carrier Using a copper electrolytic solution having the composition shown below, a cathode, and DSA (dimensionally stable anode) as an anode, electrolysis was performed at a solution temperature of 50 ° C. and a current density of 70 A / dm ² . An electrolytic copper foil having a thickness of 18 μm was produced as a carrier. At this time, as a cathode, an electrode whose surface was polished with a # 2000 buff to adjust the surface roughness was used.
<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

(2) Formation of release layer The electrode surface of the pickled carrier is placed in a CBTA aqueous solution containing a carboxybenzotriazole (CBTA) concentration of 1 g / L, a sulfuric acid concentration of 150 g / L and a copper concentration of 10 g / L at a liquid temperature of 30 ° C. The CBTA component was adsorbed on the electrode surface of the carrier. In this way, the CBTA layer was formed as an organic release layer on the electrode surface of the carrier.

(3) Formation of Auxiliary Metal Layer The carrier on which the organic exfoliation layer is formed is immersed in a solution containing nickel sulfate and having a nickel concentration of 20 g / L, so that the liquid temperature is 45 ° C., pH 3 and the current density is 5 A /. Under ^{the condition of dm 2} , an adhering amount of nickel corresponding to a thickness of 0.001 μm was adhered on the organic release layer. In this way, a nickel layer was formed as an auxiliary metal layer on the organic release layer.

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

(5) Roughing Treatment The surface of the ultrathin copper foil thus formed was roughened to form a roughened copper foil, whereby a copper foil with a carrier was obtained. This roughening treatment comprises a burn-plating step of depositing and adhering fine copper particles on an ultrathin copper foil, and a covering plating step for preventing the fine copper grains from falling off. In the burn-plating step, carboxybenzotriazole (CBTA) having a concentration shown in Table 1 is added to an acidic copper sulfate solution containing a copper concentration of 10 g / L and a sulfuric acid concentration of 200 g / L at a liquid temperature of 25 ° C. and shown in Table 1. Roughening treatment was performed at the current density. In the subsequent cover plating step, electrodeposition was performed using an acidic copper sulfate solution containing a copper concentration of 70 g / L and a sulfuric acid concentration of 240 g / L under smooth plating conditions of a liquid temperature of 52 ° C. and a current density shown in Table 1. .. At this time, various samples having different roughening-treated surface characteristics were prepared by appropriately changing the CBTA concentration and current density in the burn-plating step and the current density in the cover plating step as shown in Table 1.

(6) Rust prevention treatment The surface of the obtained roughened copper foil with a carrier was subjected to a rust prevention treatment consisting of a zinc-nickel alloy plating treatment and a chromate treatment. First, using a solution containing a zinc concentration of 1 g / L, a nickel concentration of 2 g / L, and a potassium pyrophosphate concentration of 80 g / L, the roughening treatment layer and carriers ^{are used under the conditions of a liquid temperature of 40 ° C. and a current density of 0.5 A / dm 2.} The surface of the surface was plated with a zinc-nickel alloy. Next, using an aqueous solution containing 1 g / L of chromic acid, the surface subjected to the zinc-nickel alloy plating treatment was subjected to chromate treatment under the conditions of ^{pH 12 and a current density of 1 A / dm 2.}

(7) Silane Coupling Agent Treatment A silane coupling agent treatment is performed by adsorbing a commercially available aqueous solution containing a silane coupling agent on the surface of the copper foil with a carrier to roughen the copper foil side and evaporating the water content with an electric heater. Was done. At this time, the silane coupling agent treatment was not performed on the carrier side.

(8) Evaluation Various characteristics of the copper foil with a carrier thus obtained were evaluated as follows.

(8a) Surface Texture Parameter of Roughened Surface By surface roughness analysis using a laser microscope (OLS5000, manufactured by Olympus Corporation), the roughened surface of the roughened copper foil was measured in accordance with ISO25178. .. ^{Specifically, the surface profile of a region having an area of 16384 μm 2 on} the roughened surface of the roughened copper foil was measured with the above laser microscope with a 100x lens having a numerical aperture (NA) of 0.95. After removing noise and correcting the inclination of the primary linear surface on the surface profile of the obtained roughened surface, the maximum height Sz, the developed area ratio Sdr of the interface, and the aspect ratio Str of the surface texture were analyzed by surface texture analysis. The level difference Sk of the core part and the peak density Spd of the peak were measured. At this time, the Sz, Sdr, Str and Sk were measured with the cutoff wavelength of the S filter set to 0.55 μm and the cutoff wavelength of the L filter set to 10 μm. On the other hand, in the measurement of Spd, the cutoff wavelength by the S filter was set to 3 μm, and the cutoff wavelength by the L filter was set to 10 μm. The results were as shown in Table 1.

(8b) Circuit formability (evaluation of etchability)
An evaluation laminate was prepared using the obtained copper foil with a carrier. That is, as shown in FIG. 5, roughened copper foil with a carrier is provided on the surface of the insulating resin substrate 111 via a prepreg 112 (GHPL-830NSF, thickness 0.1 mm, manufactured by Mitsubishi Gas Chemical Company, Inc.). The foil 110 was laminated and thermocompression bonded at a pressure of 4.0 MPa and a temperature of 220 ° C. for 90 minutes, and then the carrier (not shown) was peeled off to obtain a copper-clad laminate as the evaluation laminate 114. In the example shown in FIG. 5, the roughened copper foil 110 includes roughened particles 110a on its surface. In the etching property evaluation, the required etching amount varies depending on the thickness of the ultrathin copper foil. Therefore, as shown in FIG. 5, the thickness of the roughened copper foil 110 in the evaluation laminate 114 is equivalent to 1.5 μm (excluding the thickness of the roughened particles 110a) for evaluation. The thickness of the laminate 114 was reduced by half-etching or increased by copper sulfate plating, if necessary. The evaluation laminate 114 whose thickness of the roughened copper foil 110 was adjusted to 1.5 μm was etched with a sulfuric acid-hydrogen peroxide-based etching solution by 0.1 μm, and the surface copper (roughened particles 110a) was etched. The amount (depth) until completely disappeared (including) was measured. The measurement was performed by confirming with an optical microscope (500 times). More specifically, the work of confirming the presence or absence of copper with an optical microscope was repeated every time 0.1 μm was etched, and the value (μm) obtained by (number of etchings) × 0.1 μm was used as an index of etchability. For example, an etching property of 2.5 μm means that after 25 times of etching of 0.1 μm, residual copper is no longer detected by the optical microscope (that is, 0.1 μm × 25 times = 2.5 μm). ). That is, the smaller this value is, the smaller the number of times of etching is required to remove the copper on the surface. That is, the smaller this value is, the better the etching property is. The measured etching amount was rated and evaluated according to the following criteria, and if it was evaluated as any of A to C, it was judged to be acceptable. The results were as shown in Table 1.
<Etching property evaluation criteria>
-Evaluation A: Required etching amount is 2.3 μm or less-Evaluation B: Required etching amount exceeds 2.3 μm and 2.5 μm or less-Evaluation C: Required etching amount exceeds 2.5 μm and 2.7 μm Below-Evaluation D: Required etching amount exceeds 2.7 μm

(8c) Plating circuit adhesion (share strength)
A dry film was attached to the above-mentioned evaluation laminate, and exposure and development were performed. A copper layer having a thickness of 14 μm was deposited on the laminate masked with the developed dry film by pattern plating, and then the dry film was peeled off. A circuit sample for measuring shear strength having a height of 15 μm, a width of 10 μm, and a length of 200 μm by etching the copper portion exposed with a sulfuric acid-hydrogen peroxide-based etching solution (laminate 134 on which the circuit 136 shown in FIG. 6 is formed). ) Was prepared. Using a junction strength tester (4000 Plus Bondester manufactured by Nordson DAGE), the shear strength when the circuit 136 was pushed from the side of the circuit sample for shear strength measurement was measured. That is, as shown in FIG. 6, the laminated body 134 on which the circuit 136 is formed is placed on the movable stage 132, and the stage 132 is moved in the direction of the arrow in the drawing to the detector 138 which is fixed in advance. By pressing the circuit 136, a lateral force was applied to the side surface of the circuit 136 to shift the circuit 136 laterally, and the force (gf) at that time was measured by the detector 138 and adopted as the share strength. At this time, the test type was a fracture test, and the measurement was performed under the conditions of a test height of 5 μm, a descent speed of 0.050 mm / s, a test speed of 200 μm / s, a tool movement amount of 0.05 mm, and a fracture recognition point of 10%. The obtained share strength was rated and evaluated according to the following criteria, and if it was evaluated as any of A to C, it was judged to be acceptable. The results were as shown in Table 1.
<Share strength evaluation criteria>
-Evaluation A: Share strength is 13.50 gf or more-Evaluation B: Share strength is 12.50 gf or more and less than 13.50 gf-Evaluation C: Share strength is 12.00 gf or more and less than 12.50 gf-Evaluation D: Share strength is 12. Less than 00gf

Example 8 (comparison)
Copper foils with carriers were prepared and evaluated in the same manner as in Example 1 except for the following a) to c). The results were as shown in Table 1.
a) Career preparation was performed according to the procedure shown below.
b) Instead of the electrode surface of the carrier, a release layer, an auxiliary metal layer and an ultrathin copper foil were formed on the precipitation surface of the carrier in this order.
c) Instead of the burnt plating step and the cover plating step, the ultrathin copper foil was roughened by the black plating step shown below.

(Career preparation)
A sulfuric acid acidic copper sulfate solution having the composition shown below was used as the copper electrolytic solution, a titanium electrode having a surface roughness Ra of 0.20 μm was used as the cathode, and DSA (dimensional stability anode) was used as the anode. Electrolysis was performed at a solution temperature of 45 ° C. and a current density of 55 A / dm ² , and an electrolytic copper foil having a thickness of 12 μm was obtained as a carrier.
<Composition of sulfuric acid acidic 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

(Black plating process)
The surface of the ultrathin copper foil is electrolyzed using a copper electrolytic solution for black roughening having the composition shown below under ^{the conditions of a solution temperature of 30 ° C., a current density of 50 A / dm 2} , and a time of 4 sec to roughen the black. Was done.
<Composition of copper electrolytic solution for black roughening>
-Copper concentration: 13 g / L
-Sulfuric acid concentration: 70 g / L
-Chlorine concentration: 35 mg / L
-Sodium polyacrylate concentration: 400ppm

 

Claims (11)

1. A roughened copper foil having a roughened surface on at least one side.
   The roughened surface has an interface development area ratio Sdr of 3.50% or more and 12.00 measured under the conditions of a cutoff wavelength of 0.55 μm by the S filter and a cutoff wavelength of 10 μm by the L filter in accordance with ISO25178. % Or less, and the level difference Sk of the core portion measured under the conditions of a cutoff wavelength of 0.55 μm by the S filter and a cutoff wavelength of 10 μm by the L filter in accordance with ISO25178 is 0.15 μm or more and 0.35 μm or less. , Roughened copper foil.
2. The roughened copper according to claim 1, wherein Sk / Sdr, which is the ratio of the level difference Sk (μm) of the core portion to the developed area ratio Sdr (%) of the interface, is 0.038 or more and 0.050 or less. Foil.
3. The roughened surface has a maximum height Sz (μm) measured under the conditions of a cutoff wavelength of 0.55 μm by an S filter and a cutoff wavelength of 10 μm by an L filter in accordance with ISO25178, and a level difference Sk of the core portion. The roughened copper foil according to claim 1 or 2, wherein Sz × Sk, which is the product of (μm), is 0.25 or more and 0.50 or less.
4. The 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 4} mm- ² measured under the conditions of a cutoff wavelength of 3.0 μm by the S filter and a cutoff wavelength of 10 μm by the L filter in accordance with ISO25178. The roughened copper foil according to any one of claims 1 to 4, which is 3.00 × 10 ⁴ mm- ^{2 or less.}
6. The roughened surface has a surface aspect ratio Str of 0.2 or more and 0.5 or less measured under the conditions of a cutoff wavelength of 0.55 μm by an S filter and a cutoff wavelength of 10 μm by an L filter in accordance with ISO25178. The roughened copper foil according to any one of claims 1 to 5.
7. The roughened surface has a maximum height Sz of 1.6 μm or less measured under the conditions of a cutoff wavelength of 0.55 μm by the S filter measured in accordance with ISO25178 and a cutoff wavelength of 10 μm by the L filter. The roughened copper foil according to any one of claims 1 to 6.
8. The roughened copper foil according to any one of claims 1 to 7, further comprising a rust preventive treatment layer and / or a silane coupling agent layer on the roughened surface.
9. The roughened copper foil according to any one of claims 1 to 8, wherein the carrier, the peeling layer provided on the carrier, and the roughened copper foil provided on the peeling layer with the roughened surface facing outward. Copper foil with carrier.
10. A copper-clad laminate provided with the roughened copper foil according to any one of claims 1 to 8.
11. A printed wiring board provided with the roughened copper foil according to any one of claims 1 to 8.
    
    

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