JP7259093B2 - Roughened copper foil, copper foil with carrier, copper clad laminate and printed wiring board - Google Patents

Description

TECHNICAL FIELD 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 miniaturization of circuits. The MSAP method is a technique suitable for forming extremely fine circuits, and is carried out using a copper foil with a carrier in order to take advantage of its characteristics. For example, as shown in FIGS. 1 and 2, an ultra-thin copper foil 10 is pressed onto an insulating resin substrate 11 having a lower layer circuit 11b on a base substrate 11a using a prepreg 12 and a primer layer 13 to adhere to it. (step (a)), and after peeling off the carrier (not shown), via holes 14 are formed by laser drilling as needed (step (b)). Next, after applying chemical copper plating 15 (step (c)), a predetermined pattern is masked by exposure and development using dry film 16 (step (d)), and electrolytic copper plating 17 is applied (step (e )). After the dry film 16 is removed to form the wiring portion 17a (step (f)), the unnecessary ultra-thin copper foil or the like between the mutually adjacent wiring portions 17a and 17a is removed by etching over the entire thickness thereof ( Step (g)), 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 ultra-thin copper foil 10 .

As a copper foil subjected to such a roughening treatment, for example, Patent Document 1 (Japanese Patent No. 6462961) discloses that a roughening treatment layer, an antirust treatment layer and a silane coupling layer are provided on at least one side of the copper foil. Surface-treated copper foils laminated in this order are disclosed. In Patent Document 1, for the purpose of manufacturing a printed wiring board having 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, a root mean square surface gradient Sdq of 25° or more and 70° or less, and a surface texture aspect ratio Str of 0.25 or more and 0.79 or less.

In fact, several copper foils with carriers excellent in fine circuit formability have been proposed by the MSAP method or the like. For example, in Patent Document 2 (International Publication No. 2016/117587), the average distance between surface peaks on the side of the release layer is 20 μm or less, and the maximum height difference of the undulations on the side opposite to the release layer is A carrier-attached copper foil comprising an ultra-thin copper foil having a thickness of 1.0 μm or less is disclosed, and according to this aspect, it is said that both fine circuit formability and laser processability can be achieved. In addition, in Patent Document 3 (Japanese Patent Application Laid-Open No. 2018-26590), for the purpose of improving fine circuit formability, the maximum peak height Sp and the protruding peak height Sp in accordance with ISO25178 on the surface of the ultra-thin copper layer side A carrier-attached copper foil having a ratio Sp/Spk to Spk of 3.271 or more and 10.739 or less is disclosed.

Japanese Patent No. 6462961 WO2016/117587 JP 2018-26590 A

In recent years, in order to form finer circuits by the above-described MSAP method or the like, further smoothing of the copper foil and miniaturization of roughening particles are required. However, by smoothing the copper foil and miniaturizing the roughening particles, the etching property of the copper foil, which is related to miniaturization of the circuit, is improved, but the physical adhesion between the copper foil and the substrate resin, etc. is reduced. . In particular, as circuits become finer, physical stress (that is, shear stress) is applied to the circuit from the lateral direction during the mounting process of the printed wiring board, making it easier for the circuit to peel off, resulting in a decrease in yield. It is manifesting. In this respect, shear strength (shear strength) is one of the physical adhesion indices between the circuit and the substrate, and in order to effectively avoid the above-mentioned circuit peeling, it is required to maintain the shear strength at a certain level or more. However, in order to secure a certain level of shear strength, the roughened particles of the copper foil must be made large, and there is a problem that it is difficult to achieve compatibility with the etching property.

The present inventors have recently found that the roughened copper foil is provided with a surface profile in which the developed area ratio Sdr of the interface and the level difference Sk of the core part specified in ISO25178 are controlled within predetermined ranges, respectively. The present inventors have found that both excellent etching properties and high shear strength can be achieved in the processing of clad laminates or the manufacture of printed wiring boards.

Accordingly, 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 manufacture 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 developed area ratio Sdr of 3.50% or more and 12.00 measured under the conditions of an S filter cutoff wavelength of 0.55 μm and an L filter cutoff wavelength of 10 μm in accordance with ISO 25178. % or less, and the level difference Sk of the core portion measured in accordance with ISO 25178 under the conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter is 0.15 μm or more and 0.35 μm or less. , a roughened copper foil is provided.

According to another aspect of the present invention, 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 are A copper foil with carrier is provided.

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

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

FIG. 2 is a flow chart of the steps for explaining the MSAP method, showing the first half of the steps (steps (a) to (d)). FIG. 2 is a flow chart of the steps for explaining the MSAP method, showing the latter half of the steps (steps (e) to (g)). FIG. 4 is a diagram for explaining a load curve and a load area ratio determined according to ISO25178; FIG. 10 is a diagram for explaining a load area ratio Smr1 for separating the protruding peak portion and the core portion, a load area ratio Smr2 for separating the protruding valley portion and the core portion, and a level difference Sk between the core portions, which are determined in accordance with ISO25178; be. It is a schematic cross section which shows an example of the laminated body for evaluation just before performing an etching in circuit formability (etchability evaluation). It is a schematic diagram for demonstrating the measuring method of shear strength.

DEFINITIONS Definitions of terms or parameters used to define the present invention are provided below.

As used herein, the term "developed area ratio Sdr of the interface" refers to how much the developed area (surface area) of the defined region, measured in accordance with ISO 25178, is increased relative to the area of the defined region. is a parameter. In this specification, the developed area ratio Sdr of the interface is expressed as an increase (%) of the surface area. The smaller this value, the more nearly flat the surface shape is, and the Sdr of a completely flat surface is 0%. On the other hand, the larger this value, the more uneven the surface shape. For example, if the Sdr of a surface is 40%, then this surface represents a 40% increase in surface area from a perfectly flat surface.

As used herein, the term “surface load curve” (hereinafter simply referred to as “load curve”) refers to a curve representing the height at which the load area ratio is from 0% to 100%, measured in accordance with ISO 25178. say. The load area ratio is a parameter representing the area of a region having a certain height c or higher, as shown in FIG. 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 in the load area ratio of 40% is moved from the load area ratio of 0% to the secant line. The point where the slope of is the gentlest is called the central portion of the load curve. A straight line that minimizes the sum of squares of deviations in the direction of the vertical axis with respect to the central portion is called an equivalent straight line. A portion included in the height range of 0% to 100% of the load area ratio of the equivalent straight line is called a core portion. A portion higher than the core portion is called a protruding peak portion, and a portion lower than the core portion is called a protruding valley portion.

In this specification, the “core portion level difference Sk” is a value obtained by subtracting the minimum height from the maximum height of the core portion measured in accordance with ISO 25178, and as shown in FIG. This parameter is calculated from the difference between the heights of the equivalent straight line at the load area ratio of 0% and 100%.

As used herein, "maximum height Sz" is a parameter representing the distance from the highest point to the lowest point on the surface, measured according to ISO25178.

In the present specification, the “aspect ratio Str of surface texture” is a parameter representing isotropy or anisotropy of surface texture measured in accordance with ISO25178. Str ranges from 0 to 1, and Str > 0.5 generally indicates strong isotropy, while Str < 0.3 indicates strong anisotropy.

As used herein, the term “mountain vertex density Spd” refers to a parameter representing the number of vertex points per unit area, measured in accordance with ISO25178. Only points shall be counted. A large value suggests a large number of contact points with other objects.

The developed area ratio Sdr of the interface, the level difference Sk of the core portion, the maximum height Sz, the aspect ratio Str of the surface texture, and the peak density Spd of the peaks are determined by a predetermined measurement area (for example, a two-dimensional area of 16384 μm ² on the roughened surface ) can be calculated by measuring the surface profile of ) with a commercially available laser microscope. In this 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. A value measured at a wavelength of 10 μm. In the present specification, the value of peak density Spd is a value measured under the conditions of a cutoff wavelength of 3 μm by an S filter and a cutoff wavelength of 10 μm by an L filter.

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

In this specification, the "deposited surface" of the carrier refers to the surface on which electrolytic copper is deposited during carrier production, that is, the surface 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. This roughened surface has an interface development area ratio Sdr of 3.50% or more and 12.00% or less, and a level difference Sk of the core portion of 0.15 μm or more and 0.35 μm or less. In this way, in the roughened copper foil, by giving a surface profile in which the interface development area ratio Sdr and the core portion level difference Sk are each controlled within a predetermined range, processing of a copper clad laminate or printed wiring board In the production of, it is possible to achieve both excellent etchability and high shear strength.

Excellent etchability and high shear strength are inherently incompatible. As mentioned above, in order to improve the etchability of the copper foil, it is generally required to reduce the size of the roughening particles, while in order to increase the shear strength of the circuit, it is generally necessary to reduce the size of the roughening particles. This is because it is required to increase In particular, the shear strength is not simply proportional to the specific surface area, the roughness height, etc., which have been conventionally used for evaluation, and it has been difficult to control it. In this regard, the present inventors have found that it is effective to combine the development 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 etchability and shear strength. I found out. By controlling these surface parameters within the above-mentioned predetermined ranges, a fine surface with excellent etchability is obtained, while the surface is roughened with a bump height and a specific surface area that are convenient for ensuring high shear strength. It has been found that a treated copper foil is obtained. Thus, according to the roughened copper foil of the present invention, excellent etching properties and high shear strength can be achieved, and therefore, excellent fine circuit formability and high circuit adhesion from the viewpoint of shear strength can be achieved. It is possible to achieve both Conventionally, there is known a technique for controlling the developed area ratio Sdr, the root-mean-square surface gradient Sdq, and the aspect ratio Str of the surface properties of the surface of the surface-treated copper foil (see above-mentioned Patent Document 1). However, all of these parameters are parameters that are obtained including the protruding peaks, and if the generation of the protruding peaks is suppressed, the values of all of them may become too small. On the other hand, the present inventors controlled the level difference Sk of the core portion, which is a parameter that does not include the protruding peaks, and the development area ratio Sdr, which is a parameter including the protruding peaks. Regarding the treated surface, it is possible to suppress the occurrence of protruding peaks and to have a structure in which each of the roughened particles constituting the roughened surface evenly bites into the resin. It has been found that a roughened copper foil can be obtained that has a bump height and a specific surface area that are convenient for ensuring high shear strength even though it is a surface.

From the viewpoint of achieving good etchability and high shear strength in a well-balanced manner, the roughened copper foil has a developed area ratio Sdr of the interface on the roughened surface of 3.50% or more and 12.00% or less, preferably It is 4.50% or more and 8.50% or less, more preferably 4.50% or more and 6.00% or less. Within this range, a fine surface (roughened height) with excellent etchability is obtained, while ensuring a sufficient bonding area with the resin that is laminated during the production of copper-clad laminates or printed wiring boards. It is possible to improve the circuit adhesion from the viewpoint of shear strength.

From the viewpoint of achieving excellent etchability and high shear strength in a well-balanced manner, the roughened copper foil has a core portion level difference Sk of 0.15 μm or more and 0.35 μm or less, preferably 0.15 μm or more and 0.35 μm or less. 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 is fine (roughened height) with excellent etchability, the roughened particles that make up the roughened surface can evenly bite into the resin. , the adhesion to the resin is improved. In other words, if there is unevenness in the roughening treatment, it is considered that the unevenness becomes a protruding ridge on the roughened surface. However, such unevenness (protruding ridges) hardly contributes to improvement of circuit adhesion in terms of shear strength. In this regard, the maximum height Sz and the like that have been used in conventional evaluations are parameters that include the protruding ridges. Therefore, when attempting to improve the circuit adhesion based on such parameters, the height of the roughening tends to increase, and hence the etchability tends to decrease. 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 to the resin, and as a result, it is possible to suppress an increase in the roughness height. is also possible.

In the roughened copper foil, 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 on the roughened surface, is 0.038 or more and 0.050 or less. 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 reduced 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 that excludes the protruding peak portion, while the developed area ratio Sdr is a parameter that includes the protruding peak portion. Therefore, when the number of protruding peaks increases or decreases, the value of the developed area ratio Sdr changes, although the value of the level difference Sk of the core portion remains constant. Therefore, by controlling the ratio between 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 ridges on the roughened surface. , each of the roughening particles constituting the roughening-treated surface can easily bite into the resin on average. As a result, excellent etchability and high shear strength can be achieved in a well-balanced manner.

In the roughened copper foil, 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, is preferably 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 such that the occurrence of protruding ridges is further suppressed, and it is more suitable for realizing excellent etching properties and high shear strength in a well-balanced manner. Become. In addition, from the viewpoint of realizing a fine surface with more excellent 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. 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 crest density Spd of 2.00×10 ⁴ mm ⁻² or more and 3.00×10 ⁴ mm ⁻² or less, more preferably 2.20. ×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 sufficient bonding points with the resin that is laminated during the production of the copper-clad laminate or printed wiring board, and it is possible to more effectively improve the circuit adhesion in terms of shear strength. can.

The surface texture aspect ratio Str of the roughened surface 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 still more preferably 0.50 or less. It is 45 or more and 0.50 or less. Within this range, the roughened surface has undulations that are favorable for adhesion with the resin. As a result, it is possible to more effectively improve the circuit adhesion from the viewpoint of shear strength even though the surface is fine and has excellent etching properties.

Although the thickness of the roughened copper foil is not particularly limited, it 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 still more preferably 1.0 μm or more and 3.0 μm or less. The roughened copper foil is not limited to a general copper foil whose surface has been roughened, and may be a carrier-attached copper foil whose copper foil surface has been roughened. Here, the thickness of the roughened copper foil is the thickness not including the height of the roughened particles formed on the surface of the roughened surface (thickness of the copper foil itself constituting the roughened copper foil). is. A copper foil having a thickness within the above range is sometimes called an ultra-thin 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 a roughened surface only on one side. The roughened surface is typically provided with a plurality of roughening particles (nobs), and each of these roughening particles preferably consists of copper particles. The copper particles may consist of metallic copper, or may consist of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably carried out by forming roughening particles with copper or a copper alloy on the copper foil. For example, roughening treatment according to a plating method that undergoes at least two plating processes including a baking plating process for depositing fine copper grains on a copper foil and a covering plating process for preventing the fine copper grains from falling off. is preferably performed. In this case, in the burn plating process, 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 is added with carboxybenzotriazole (CBTA) at a concentration of 20 ppm to 29 ppm. It is preferable that the electrodeposition is carried out at a temperature of 15° C. or higher and 35° C. or lower at a temperature of 14 A/dm ² or higher and 24 A/dm ^{2 or} lower. In addition, the covering plating step is carried out at a temperature of 40 to 60°C 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 2 A/dm ² or more. Electrodeposition is preferably performed at 4 A/dm ² or less. In particular, in the burnt plating process, by adding carboxybenzotriazole within the above concentration range to the plating solution, it is possible to suppress the occurrence of protruding ridges on the roughened surface while maintaining etching properties close to that of pure copper, and In addition, roughened particles forming the roughened surface can evenly bite into the resin, making it easy to form bumps on the treated surface that are convenient for satisfying the surface parameters described above. Furthermore, in the burn plating process and the covering plating process, by performing electrodeposition with a lower current density than in the conventional method, it becomes easier to form convenient bumps on the treated surface to satisfy the above-mentioned surface parameters.

If desired, the roughened copper foil may be subjected to an antirust treatment to form an antirust layer. The antirust treatment preferably includes plating with zinc. The plating treatment using zinc may be either zinc plating treatment or zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably 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 to 10, more preferably 2 to 7, and still more preferably 2.7 to 4 in mass ratio. In addition, the rust prevention treatment preferably further includes chromate treatment, and this chromate treatment is more preferably performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust resistance can be further improved. A particularly preferred antirust treatment is a combination of zinc-nickel alloy plating treatment and 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 adhesives and the like can be improved. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, coating it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltrimethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. amino-functional silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacrylic Acrylic functional silane coupling agents such as roxypropyltrimethoxysilane, or imidazole functional silane coupling agents such as imidazole silane, or triazine functional silane coupling agents such as triazine silane, and the like.

For the reasons described above, the roughened copper foil preferably further comprises an antirust treatment layer and/or a silane coupling agent layer on the roughened surface, more preferably the antirust treatment layer and the silane coupling agent layer. Have both. The antirust 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.

Carrier-attached copper foil 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, a release layer provided on the carrier, and the roughened copper foil provided on the release layer with the roughened surface facing outward, A copper foil with carrier is provided. However, for the carrier-attached copper foil, a known layer structure can be employed, except for using the roughened copper foil of the present invention.

A carrier is a support for supporting the roughened copper foil to improve its handleability, and a typical carrier includes a metal layer. Examples of such a carrier 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 a rolled copper foil or an electrolytic copper foil, 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.

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 ultra-thin copper foil (before roughening treatment) is formed on the release layer side surface of the carrier. 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 ultra-thin copper foil. Therefore, by smoothing the surface of the carrier on the release layer side, the outer surface of the ultra-thin copper foil can also be smoothed. It becomes easy to realize a roughened surface having the developed area ratio Sdr of the interface and the level difference Sk of the core portion within the predetermined ranges. The surface of the carrier on the release layer side can be smoothed, for example, by polishing the surface of the cathode used in electrolytic foil production of the carrier with a buff of a predetermined number to adjust the surface roughness. That is, the surface profile of the cathode adjusted in this way is transferred to the electrode surface of the carrier, and an ultra-thin copper foil is formed on the electrode surface of the carrier with a release layer interposed therebetween. It is possible to impart a smooth surface condition that facilitates the realization of the roughened surface described above. The buff number is preferably #2000 or more and #3000 or less, more preferably #2000 or more and #2500 or less.

The release layer is a layer that has the function of weakening the peeling strength of the carrier, ensuring the stability of the strength, and suppressing interdiffusion that may occur between the carrier and the copper foil during press molding at high temperatures. . The release layer is generally formed on one side 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 organic components used in the organic release layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids, and the like. Examples of the nitrogen-containing organic compound include triazole compounds, imidazole compounds, etc. Among them, triazole compounds are preferable in terms of easily stabilizing peelability. 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 and the like. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, 2-benzimidazolethiol, and the like. Examples of carboxylic acids include monocarboxylic acids, dicarboxylic acids, and the like. On the other hand, examples of inorganic components used for the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, chromate treatment films, and the like. The release layer may be formed by contacting at least one surface of the carrier with a release layer component-containing solution to fix the release layer component on 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, or flowing the release layer component-containing solution. In addition, it is also possible to adopt a method of forming a coating of the peeling layer component by a vapor phase method such as vapor deposition or sputtering. Fixing of the release layer component to the carrier surface may be carried out 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, other functional layers may be provided between the release layer and the carrier and/or roughened copper foil. Examples of such other functional layers include auxiliary metal layers. The auxiliary metal layer preferably consists 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, during hot press molding at high temperature or for a long time, it may occur between the carrier and the roughened copper foil. Mutual diffusion can be suppressed and the stability of carrier peeling strength 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 a copper-clad laminate for printed wiring boards. That is, according to a preferred aspect of the present invention, there is provided a copper-clad laminate comprising the roughened copper foil. By using the roughened copper foil of the present invention, it is possible to achieve both excellent etchability and high shear 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 comprises resin, preferably insulating resin. The resin layer is preferably prepreg and/or resin sheet. Prepreg is a general term for composite materials in which synthetic resin is impregnated into a base material such as a synthetic resin plate, a glass plate, a glass woven fabric, a glass non-woven fabric, or paper. Preferred examples of insulating resins include epoxy resins, cyanate resins, bismaleimide triazine resins (BT resins), polyphenylene ether resins, and phenol resins. Examples of the insulating resin forming the resin sheet include insulating resins such as epoxy resins, polyimide resins, and polyester resins. In addition, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation. Although the thickness of the resin layer is not particularly limited, it is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and still more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and/or a resin sheet may be provided on the roughened copper foil in advance via a primer resin layer that is 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 aspect of the present invention, there is provided a printed wiring board comprising the roughened copper foil. By using the roughened copper foil of the present invention, both excellent etchability and high shear strength can be achieved in the production of printed wiring boards. The printed wiring board according to this aspect 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. Also, the resin layer is as described above for the copper-clad laminate. In any case, the printed wiring board can employ a known layer structure except for using the roughened copper foil of the present invention. Specific examples of printed wiring boards include a single-sided or double-sided printed wiring board formed by bonding the roughened copper foil of the present invention to one or both sides of a prepreg to form a cured laminate, and then forming a circuit on the printed wiring board. A multilayer printed wiring board etc. are mentioned. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc., in which the roughened copper foil of the present invention is formed on a resin film to form a circuit. As another specific example, a resin-coated copper foil (RCC) is formed by applying the above resin layer to the roughened copper foil of the present invention, and the resin layer is used as an insulating adhesive layer and laminated on the above printed circuit board. After that, the roughened copper foil is used as all or part of the wiring layer, and the circuit is formed by the modified semi-additive (MSAP) method, the subtractive method, etc. The build-up wiring board and the roughened copper foil are removed. 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 lamination of resin-coated copper foil on a semiconductor integrated circuit and circuit formation are alternately repeated. More advanced specific examples include antenna elements in which the resin-coated copper foil is laminated on a base material to form a circuit, and electronic materials and windows for panels and displays in which a pattern is formed by laminating the resin-coated copper foil on glass or a resin film via an adhesive layer. An electronic material for glass, an electromagnetic wave shielding film obtained by applying a conductive adhesive to the roughened copper foil of the present invention, and the like are also included. 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 configurations shown in FIGS. 1 and 2 can be adopted.

The invention is further illustrated by the following examples.

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

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

(2) Formation of release layer The electrode surface of the pickled carrier was immersed in a CBTA aqueous solution containing 1 g/L of carboxybenzotriazole (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. Thus, a 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 release layer was formed was immersed in a solution containing nickel concentration of 20 g/L prepared using nickel sulfate, and the liquid temperature was 45° C., pH 3, current density 5 A/L. Under conditions of dm ² , a deposition amount of nickel equivalent to a thickness of 0.001 μm was deposited onto the organic release layer. Thus, 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, and the solution temperature is 50 ° C. and the current density is 5 A/dm ² or more and 30 A/dm ² or less. Electrolysis was performed to form an ultra-thin copper foil having a thickness of 1.5 μm on the auxiliary metal layer.
<Solution composition>
- Copper concentration: 60g/L
- Sulfuric acid concentration: 200 g / L

(5) Roughening Treatment The surface of the ultra-thin 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 baking plating process for depositing fine copper grains on an ultrathin copper foil and a covering plating process for preventing the fine copper grains from falling off. In the burnt plating process, carboxybenzotriazole (CBTA) at the concentration shown in Table 1 was 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. Roughening treatment was performed at a current density. In the subsequent overplating process, an acidic copper sulfate solution containing a copper concentration of 70 g/L and a sulfuric acid concentration of 240 g/L was used, and electrodeposition was performed under smooth plating conditions of a liquid temperature of 52° C. and a current density shown in Table 1. . At this time, by appropriately changing the CBTA concentration and current density in the baking plating process and the current density in the covering plating process as shown in Table 1, various samples with different characteristics of the roughened surface were produced.

(6) Antirust Treatment The roughened surface of the obtained copper foil with carrier was subjected to antirust treatment comprising zinc-nickel alloy plating treatment and 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, under the conditions of a liquid temperature of 40 ° C. and a current density of 0.5 A / dm ² , the roughening treatment layer and the carrier A zinc-nickel alloy plating treatment was performed on the surface of the Next, the zinc-nickel alloy plated surface was subjected to chromate treatment using an aqueous solution containing 1 g/L of chromic acid under the conditions of pH 12 and current density 1 A/dm ² .

(7) Silane coupling agent treatment An aqueous solution containing a commercially available silane coupling agent is adsorbed on the surface of the roughened copper foil side of the carrier-attached copper foil, and the water is evaporated with an electric heater to perform the silane coupling agent treatment. did At this time, the carrier side was not treated with the silane coupling agent.

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

(8a) Surface property 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 using a 100-fold lens with a numerical aperture (NA) of 0.95. After performing noise removal and first-order linear surface inclination correction on the obtained surface profile of the roughened surface, the maximum height Sz, the interface development area ratio Sdr, the surface texture aspect ratio Str, The level difference Sk of the core portion and the apex density Spd of the peaks were measured. At this time, 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, Spd was measured by setting the cutoff wavelength of the S filter to 3 μm and the cutoff wavelength of the L filter to 10 μm. The results were as shown in Table 1.

(8b) circuit formability (evaluation of etching property)
A laminate for evaluation was produced using the obtained copper foil with a carrier. That is, as shown in FIG. 5, on the surface of an insulating resin substrate 111, a roughened copper foil with a carrier is applied via a prepreg 112 (GHPL-830NSF, manufactured by Mitsubishi Gas Chemical Co., Inc., thickness 0.1 mm). After laminating the foil 110 and thermocompression bonding at a pressure of 4.0 MPa and a temperature of 220° C. for 90 minutes, the carrier (not shown) was peeled off to obtain a copper-clad laminate as a laminate 114 for evaluation. In the example shown in FIG. 5, the roughened copper foil 110 has roughened particles 110a on its surface. In the evaluation of etching property, the required etching amount varies depending on the thickness of the ultra-thin copper foil. For this reason, as shown in FIG. 5, the thickness of the roughened copper foil 110 in the evaluation laminate 114 is equivalent to 1.5 μm (not including the thickness of the roughening particles 110a). The laminated body 114 was reduced in thickness by half-etching or increased in thickness by copper sulfate plating, if necessary. The thickness of the roughened copper foil 110 was adjusted to 1.5 μm, and the evaluation laminate 114 was etched with a sulfuric acid-hydrogen peroxide-based etching solution by 0.1 μm, and the surface copper (roughened particles 110a ) was measured until the amount (depth) completely disappeared. Measurement was performed by confirming with an optical microscope (500 times). More specifically, the presence or absence of copper was repeatedly checked with an optical microscope each time etching was performed by 0.1 μm, and the value (μm) obtained by (the number of times of etching)×0.1 μm was used as an etchability index. For example, an etchability of 2.5 μm means that after 25 etchings of 0.1 μm, no residual copper was detected with an optical microscope (i.e., 0.1 μm×25 times=2.5 μm ). In other words, the smaller this value, the smaller the number of times of etching, which means that the copper on the surface can be removed. That is, it means that the smaller this value, the better the etchability. The measured etching amount was graded and evaluated according to the following criteria, and any one of the evaluations A to C was judged to be acceptable. The results were as shown in Table 1.
<Etching Evaluation Criteria>
-Evaluation A: Required etching amount is 2.3 μm or less -Evaluation B: Required etching amount is more than 2.3 μm and is 2.5 μm or less -Evaluation C: Required etching amount is more than 2.5 μm and is 2.7 μm Below - Evaluation D: Required etching amount exceeds 2.7 μm

(8c) Plating circuit adhesion (shear strength)
A dry film was attached to the laminate for evaluation described above, and exposure and development were performed. After depositing a copper layer with a thickness of 14 μm by pattern plating on the laminate masked with the developed dry film, the dry film was peeled off. The exposed copper portion was etched with a sulfuric acid-hydrogen peroxide-based etchant, and a circuit sample for shear strength measurement with a height of 15 μm, a width of 10 μm, and a length of 200 μm (a laminate 134 on which a circuit 136 shown in FIG. 6 was formed) was obtained. ) was made. Using a bonding 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, a laminated body 134 having a circuit 136 formed thereon is placed on a movable stage 132, and moved together with the stage 132 in the direction of the arrow in the figure, so that a detector 138 fixed in advance is moved. By pressing the circuit 136, a lateral force was applied to the side surface of the circuit 136 to shift the circuit 136 laterally. At this time, the test type was a destructive test, and the measurement was performed under the conditions of a test height of 5 μm, a descending speed of 0.050 mm/s, a test speed of 200 μm/s, a tool movement of 0.05 mm, and a rupture recognition point of 10%. The shear strength thus obtained was graded and evaluated according to the following criteria, and any one of the evaluations A to C was judged to be acceptable. The results were as shown in Table 1.
<Share 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 of 12.0 gf or more less than 00gf

Example 8 (Comparison)
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 were as shown in Table 1.
a) The carrier has been prepared in accordance with the procedures set forth below.
b) Instead of the electrode surface of the carrier, a release layer, an auxiliary metal layer and an ultra-thin copper foil are formed in this order on the deposition surface of the carrier.
c) Roughening treatment of the ultra-thin copper foil was performed by the black plating process shown below instead of the burn plating process and the covering plating process.

(career preparation)
Using a sulfuric acid copper sulfate solution having the composition shown below as the copper electrolyte, using a titanium electrode having a surface roughness Ra of 0.20 μm as the cathode, and using DSA (dimensionally stable anode) as the anode, Electrolysis was performed at a solution temperature of 45° C. and a current density of 55 A/dm ² to obtain an electrolytic copper foil having a thickness of 12 μm as a carrier.
<Composition of sulfuric acid copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 140g/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 ultra-thin copper foil is electrolyzed under the conditions of a solution temperature of 30° C., a current density of 50 A/dm ² , and a time of 4 sec using a copper electrolytic solution for black roughening having the composition shown below to roughen the black surface. did
<Composition of copper electrolytic solution for black roughening>
- Copper concentration: 13g/L
- Sulfuric acid concentration: 70g/L
- Chlorine concentration: 35mg/L
- Sodium polyacrylate concentration: 400 ppm

Claims (11)

A roughened copper foil having a roughened surface on at least one side,
The roughened surface has an interface developed area ratio Sdr of 3.50% or more and 12.00 measured under the conditions of an S filter cutoff wavelength of 0.55 μm and an L filter cutoff wavelength of 10 μm in accordance with ISO 25178. % or less, and the level difference Sk of the core portion measured in accordance with ISO 25178 under the conditions of a cutoff wavelength of 0.55 μm with an S filter and a cutoff wavelength of 10 μm with an L filter is 0.15 μm or more and 0.35 μm or less. , roughened copper foil. The roughened copper according to claim 1, wherein Sk/Sdr, which is a 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. 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 ISO 25178 and the level difference Sk of the core portion The roughened copper foil according to claim 1 or 2, wherein Sz x Sk, which is the product of (μm), is 0.25 or more and 0.50 or less. 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. The roughened surface has a crest density Spd of 2.00×10 ⁴ mm ⁻² measured under the conditions of an S filter cutoff wavelength of 3.0 μm and an L filter cutoff wavelength of 10 μm 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. The roughened surface has a surface texture aspect ratio Str of 0.2 or more and 0.5 or less measured under the conditions of an S filter cutoff wavelength of 0.55 μm and an L filter cutoff wavelength of 10 μm in accordance with ISO 25178. The roughened copper foil according to any one of claims 1 to 5, which is 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 with an S filter and a cutoff wavelength of 10 μm with an L filter, which are measured in accordance with ISO 25178. The roughened copper foil according to any one of claims 1 to 6. 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. 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. A copper foil with a carrier. A copper clad laminate comprising the roughened copper foil according to any one of claims 1 to 8. A printed wiring board comprising the roughened copper foil according to any one of claims 1 to 8.

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