JP7166335B2 - 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 SAP (semi-additive process) method has been widely adopted as a manufacturing method for printed wiring boards suitable for miniaturization of circuits. The SAP method is a method suitable for forming extremely fine circuits, and as an example, it is performed using a roughened copper foil with a carrier. For example, as shown in FIGS. 1 and 2, a roughened copper foil 110 is pressed onto an insulating resin substrate 111 having a base substrate 111a and a lower layer circuit 111b using a prepreg 112 and a primer layer 113 to adhere to it. (step (a)), the carrier (not shown) is peeled off from the roughened copper foil 110, and via holes 114 are formed by laser drilling as necessary (step (b)). Next, the roughened copper foil 110 is removed by etching to expose the primer layer 113 provided with the roughened surface profile (step (c)). After applying electroless copper plating 115 to this roughened surface (step (d)), it is masked with a predetermined pattern by exposure and development using a dry film 116 (step (e)), and electrolytic copper plating 117 is applied. (Step (f)). After removing the dry film 116 to form the wiring portion 117a (step (g)), the unnecessary electroless copper plating 115 between the adjacent wiring portions 117a, 117a is removed by etching (step (h)), Wiring 118 formed in a predetermined pattern is obtained.

In the SAP method using such a roughened copper foil, the roughened copper foil itself is removed by etching after laser perforation (step (c)). Since the uneven shape of the roughened surface of the roughened copper foil is transferred to the surface of the laminate from which the roughened copper foil has been removed, the insulating layer (for example, the primer layer 113 or the primer layer 113) can be used in subsequent steps. If there is no prepreg 112) and the plating circuit (for example, the wiring 118), the adhesion can be ensured. However, since the surface profile suitable for increasing the adhesion to the plating circuit generally tends to be rough unevenness, the etchability for the electroless copper plating tends to decrease in step (h). That is, as the electroless copper plating digs into the rough unevenness, more etching is required to remove residual copper.

Therefore, a method has been proposed in which roughened particles are made smaller and have a constricted shape so that when used in the SAP method, good etching properties can be achieved while ensuring the necessary adhesion of the plated circuit. . For example, Patent Document 1 (International Publication No. 2016/158775) describes a roughened copper foil having a roughened surface on at least one side, wherein the roughened surface is a plurality of substantially spherical surfaces made of copper particles. Disclosed is one comprising projections, wherein the average height of the substantially spherical projections is 2.60 μm or less.

WO2016/158775

In recent years, the adhesion strength (absolute value) between the circuit and the substrate has been reduced with the further miniaturization of the circuit required for the SAP method. By the way, as shown in FIGS. 3A and 3B, the circuit 124 formed on the substrate 122 may be covered with a solder resist 126 along its longitudinal sides (FIG. 3A) or not (FIG. 3B). be. When the circuit 124 is covered with the solder resist 126, the circuit 124 is protected by the solder resist 126, so the risk of the circuit 124 being peeled off from the substrate 122 during the working process is small, that is, the adhesion between the circuit 124 and the substrate 122 is impaired. It can be said that the risk is small. On the other hand, when the circuit 124 is not covered with the solder resist 126, the circuit 124 is not protected by the solder resist 126, so if the adhesion strength to the substrate 122 decreases due to the miniaturization of the circuit 124, the circuit 124 may peel off during the work process. risk increases. In this regard, shear strength (shear strength) is one of the physical adhesion indicators between the circuit and the substrate. The current situation is that it is not possible to convert Therefore, in order to miniaturize the circuit 124 that is not covered with the solder resist 126, it is desired that sufficient shear strength can be ensured even with a fine line width in addition to etching properties and dry film resolution. However, although the technique disclosed in Patent Literature 1 can ensure good peel strength, it is difficult to ensure sufficient shear strength capable of coping with thinning.

The present inventors have recently found that by controlling the shape of the roughened particles, the roughened copper foil has a ten-point average roughness Rz of 1.7 μm or less, which is a level suitable for fine line circuit formation. We have found that excellent circuit adhesion can be achieved in terms of shear strength. That is, even though it is a roughened copper foil with a low roughness suitable for fine circuit formation, when it is used in the SAP method, it has not only etching properties for electroless copper plating, but also circuit adhesion from the viewpoint of shear strength. It has been found that the laminate can be provided with a surface profile that is also excellent. Further, the inventors have also obtained knowledge that extremely fine dry film resolution can be achieved in the dry film development step in the SAP method by using the roughened copper foil.

Therefore, the object of the present invention is to provide a low-roughness roughened copper foil that is suitable for forming fine-line circuits, but when used in the SAP method, has not only etching properties for electroless copper plating and dry film resolution. The first object is to provide a roughened copper foil capable of imparting a laminate with a surface profile excellent in circuit adhesion in terms of shear strength. Another object of the present invention is to provide a carrier-attached copper foil comprising such a roughened copper foil.

According to one aspect of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side, the roughened surface comprising a plurality of roughened particles,
The average value of the ratio L ² /S of the square of the peripheral length L (μm) of the roughened particles to the area S (μm ² ) of the roughened particles in the cross section of the roughened copper foil having a length of 10 μm is 16 30 or less, and the roughened surface has a ten-point average roughness Rz of 0.7 μm or more and 1.7 μm or less.

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 another aspect of the present invention, there is provided a copper-clad laminate comprising the roughened copper foil or the carrier-attached copper foil.

According to another aspect of the present invention, there is provided a printed wiring board obtained using the roughened copper foil or the carrier-attached copper foil. Alternatively, according to another aspect of the present invention, there is provided a method for producing a printed wiring board, characterized by producing a printed wiring board using the roughened copper foil or the carrier-attached copper foil. .

FIG. 2 is a process flow chart for explaining the SAP method, showing the first half of the processes (processes (a) to (d)). FIG. 2 is a flow chart of steps for explaining the SAP method, showing the latter half of the steps (steps (e) to (h)). FIG. 4 is a schematic cross-sectional view showing a case where side surfaces in the longitudinal direction of a circuit are covered with a solder resist; FIG. 4 is a schematic cross-sectional view showing a case where circuits are not covered with a solder resist; 1 is a schematic cross-sectional view showing a roughened surface of a roughened copper foil of the present invention. FIG. FIG. 5 is a schematic cross-sectional view for explaining the peripheral length L and area S of roughened particles in the roughened copper foil of FIG. 4 ; 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 “roughened particles” refers to particles 12 having a height of more than 150 nm and directly formed on the surface of the base surface 10a of the roughened copper foil 10, as schematically shown in FIG. , and includes all shapes such as substantially spherical, needle-like, columnar, and elongated shapes, but preferably has the form of "substantially spherical protrusions". As used herein, the term “substantially spherical projections” refers to projections having a substantially spherical rounded shape, and is distinguished from projections or particles having anisotropic shapes such as needles, columns, and elongated shapes. be. As shown as the roughened particles 12 in FIG. 4, the substantially spherical projections are connected to the base surface 10a of the copper foil at the constricted root portion connected to the base surface 10a of the copper foil, so that they are completely spherical. However, it is sufficient if the portion other than the root portion is approximately spherical. Therefore, as long as the approximately spherical projection retains the approximately spherical rounded shape, the presence of fine unevenness and deformation is allowed. The above-mentioned projections may simply be referred to as spherical projections, but since they cannot be perfect spheres as described above, they should be interpreted as meaning the substantially spherical projections described above. Moreover, the projections 12a formed on the surfaces of the roughening particles 12, not directly on the base surface 10a of the roughening treated copper foil 10, constitute part of the roughening particles 12. FIG.

In the present specification, the “peripheral length L of the _roughening particle” means, as schematically shown in FIG. , the _total length (L _{p + L s} ). In addition, as schematically shown in FIG. 5, the "area S of the roughening particle" is the area (cross-sectional area) of the figure surrounded by the outline 12p and the line segment 12s in the cross section of the roughening particle 12. is. Peripheral length L and area S of roughened particles 12 can be specified by analyzing a cross-sectional image of roughened copper foil 10 acquired by SEM observation using commercially available software. For example, image analysis can be performed using image analysis software Image-Pro Plus 5.1J (manufactured by Media Cybernetics, Inc.) according to the conditions described in the examples of this specification.

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 metal is electrolytically 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. The roughened surface comprises a plurality of roughening particles 12, as schematically shown in FIG. The average value of the ratio L ² /S of the square of the peripheral length L (μm) of the roughened particles 12 to the area S (μm ² ) of the roughened particles 12 in the 10 μm long cross section of the roughened copper foil 10 is 16. 30 or less. The ten-point average roughness Rz of the roughened surface is 0.7 μm or more and 1.7 μm or less. By controlling the shape of the roughened particles in this way, it is possible to obtain a roughened copper foil with a low roughness level suitable for forming a fine line circuit, such as a ten-point average roughness Rz of 1.7 μm or less, but from the viewpoint of shear strength. excellent circuit adhesion can be realized. That is, even though it is a roughened copper foil with a low roughness suitable for fine circuit formation, when it is used in the SAP method, it has not only etching properties for electroless copper plating, but also circuit adhesion from the viewpoint of shear strength. can impart a superior surface profile to the laminate. Further, by using the roughened copper foil, extremely fine dry film resolution can be realized in the dry film development step in the SAP method.

It is inherently difficult to achieve both adhesion to a plated circuit and etchability to electroless copper plating. That is, as described above, the surface profile suitable for increasing the adhesion to the plating circuit generally tends to be rough unevenness, so the etchability of the electroless copper plating decreases in the step (h) of FIG. It's easy to do. That is, as the electroless copper plating digs into the rough unevenness, more etching is required to remove residual copper. In this regard, it is said that the roughened copper foil of Patent Document 1 can ensure excellent adhesion to the plated circuit while realizing a reduction in the amount of etching. However, in recent years, with the further miniaturization of circuits required for the SAP method, the adhesion strength (absolute value) between the circuit and the substrate is declining. Even if it is possible to secure it, it is difficult to secure a sufficient shear strength capable of coping with thinning. Therefore, if the circuit is not covered with the solder resist, there is a high risk of the circuit peeling off during the working process. In contrast, in the present invention, by controlling the shape of the roughened particles 12, the diameter of the roughened particles is significantly reduced to a ten-point average roughness Rz of 1.7 μm or less, a level suitable for fine line circuit formation. At the same time, it is possible to greatly improve the circuit adhesion in terms of shear strength. That is, originally, the circuit adhesion may be reduced by reducing the diameter of the roughened particles 12 represented by Rz within the above range, but in the present invention, the ratio L ² / By setting the average value of S to 16 or more and 30 or less, it is possible to realize excellent circuit adhesion from the viewpoint of shear strength. It is believed that by achieving both excellent adhesion and excellent etching properties for electroless copper plating, it is possible to achieve extremely fine dry film resolution in the dry film development process in the SAP method. . Therefore, the roughened copper foil 10 of the present invention is preferably used for producing a printed wiring board by the semi-additive process (SAP). In other words, it can be said that the roughened copper foil 10 of the present invention is preferably used for transferring the uneven shape to the insulating resin layer for printed wiring boards.

The roughened copper foil 10 of the present invention 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. In the case of having roughened surfaces on both sides, the surface on the laser irradiation side (the surface away from the surface to be adhered to the insulating resin) is also roughened when used in the SAP method, so laser absorption. As a result of the increased strength, the laser perforability can also be improved.

The roughened surface is provided with a plurality of roughening particles 12, and each of these roughening particles 12 is preferably made of copper particles. The copper particles may consist of metallic copper, or may consist of a copper alloy. However, when the copper particles are a copper alloy, the solubility in the copper etchant may be reduced, or the life of the etchant may be reduced due to the inclusion of alloy components in the copper etchant. It is preferable to consist of

The average value of the ratio L ² /S of the square of the peripheral length L (μm) of the roughened particles 12 to the area S (μm ² ) of the roughened particles 12 in the 10 μm long cross section of the roughened copper foil 10 is 16. 30 or less, preferably 19 or more and 27 or less, more preferably 19 or more and 26 or less, still more preferably 19 or more and 25 or less, and particularly preferably 20 or more and 24 or less. Within these ranges, the shear strength can be further improved while effectively preventing the roughening particles 12 from coming off.

The ten-point average roughness Rz of the roughened surface is 0.7 μm or more and 1.7 μm or less, preferably 0.7 μm or more and 1.6 μm or less, more preferably 0.8 μm or more and 1.5 μm or less. Within these ranges, the thin line formability can be further improved while ensuring the desired shear strength. Rz is determined according to JIS B 0601-1994.

The number of roughened particles 12 in a 10 μm long cross section of the roughened copper foil 10 is preferably 20 or more and 70 or less, more preferably 20 or more and 60 or less, still more preferably 20 or more and 40. It is below. Within these ranges, the shear strength can be further improved while effectively preventing the roughening particles 12 from coming off.

The thickness of the roughened copper foil 10 of the present invention is not particularly limited, but is preferably 0.1 μm or more and 18 μm or less, more preferably 0.5 μm or more and 7 μm or less, still more preferably 0.5 μm or more and 5 μm or less, and particularly preferably It is 0.5 μm or more and 3 μm or less. This thickness is the thickness including the roughening particles 12 . The roughened copper foil 10 of the present invention is not limited to a general copper foil whose surface has been roughened, but a carrier-attached copper foil whose copper foil surface has been roughened. good too.

Method for Producing Roughened Copper Foil A preferred method for producing the roughened copper foil according to the present invention will be described. It may be manufactured by any method as long as the surface profile of the treated copper foil can be achieved.

(1) Preparation of copper foil Both electrolytic copper foil and rolled copper foil can be used as the copper foil used for producing the roughened copper foil. The thickness of the copper foil is not particularly limited, but is preferably 0.1 μm or more and 18 μm or less, more preferably 0.5 μm or more and 7 μm or less, still more preferably 0.5 μm or more and 5 μm or less, and particularly preferably 0.5 μm or more and 3 μm or less. be. When the copper foil is prepared in the form of a copper foil with a carrier, the copper foil may be formed by a wet film forming method such as an electroless copper plating method and an electrolytic copper plating method, a dry film forming method such as sputtering and chemical vapor deposition, or It may be formed by a combination thereof.

(2) Roughening Treatment Copper particles are used to roughen at least one surface of the copper foil. This roughening is performed by electrolysis using a copper electrolytic solution for roughening treatment. This electrolysis is preferably carried out through a three-step plating process. In the first-stage plating process, the copper concentration is 5 g/L to 20 g/L, the sulfuric acid concentration is 30 g/L to 200 g/L, the chlorine concentration is 20 ppm to 100 ppm, and the 9-phenylacridine (9PA) concentration is 20 ppm to 100 ppm. It is preferable to perform electrodeposition under plating conditions of a solution temperature of 20° C. or higher and 40° C. or lower, a current density of 5 A/dm ² or higher and 25 A/dm ² or lower, and a time of 2 seconds or longer and 10 seconds or lower. In the second-stage plating process, a copper sulfate solution containing a copper concentration of 65 g/L or more and 80 g/L or less and a sulfuric acid concentration of 200 g/L or more and 280 g/L or less was used. Electrodeposition is preferably performed under plating conditions of a density of 1 A/dm ² or more and 10 A/dm ² or less and a time of 2 seconds or more and 25 seconds or less. In the third plating step, a copper sulfate solution containing a copper concentration of 10 g/L or more and 20 g/L or less, a sulfuric acid concentration of 30 g/L or more and 130 g/L or less, a chlorine concentration of 20 ppm or more and 100 ppm or less, and a 9PA concentration of 100 ppm or more and 200 ppm or less. Electrodeposition is preferably carried out under the following plating conditions: liquid temperature 20° C. to 40° C., current density 10 A/dm ² to 40 A/dm ² , and time 0.3 seconds to 1.0 seconds. By performing the third-stage plating process using an additive such as 9PA, fine protrusions are formed on the surface of the roughened particles formed in the first-stage and second-stage plating processes, and the ratio L ² /S can be increased. In particular, it is preferable that the _first -stage plating process is performed using an additive such as _9PA . It is preferable to set the amount (Q ₁ +Q ₂ ) to 100 C/dm ² or less. Further, the linear flow velocity of the plating solution with respect to the copper foil in the first to third plating steps is preferably 0.10 m/s or more and 0.50 m/s or less, more preferably 0.15 m/s or more and 0.5 m/s or less. .45 m/s or less. By doing this, a relatively low roughness surface profile satisfying the ten-point average roughness Rz ≤ 1.7 μm is formed, and the third-stage plating spreads over the entire surface of the roughened particles, and the ratio L ² / Roughened particles with large S are formed.

(3) Rust prevention treatment Rust prevention treatment does not affect the shape, perimeter and area of the roughened particles, and the ten-point average roughness Rz of the roughened surface, so if desired, the copper foil after roughening treatment may be subjected to anti-corrosion treatment. 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.

(4) Silane Coupling Agent Treatment If desired, the 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-aminopropyltriethoxysilane, N-2 (amino ethyl)3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacryloxypropyl Acrylic functional silane coupling agents such as trimethoxysilane, or imidazole functional silane coupling agents such as imidazole silane, or triazine functional silane coupling agents such as triazine silane, or the like.

Carrier-attached copper foil The roughened copper foil of the present invention can be provided in the form of a carrier-attached copper foil. In this case, the carrier-attached copper foil comprises a carrier, a release layer provided on the carrier, and the roughened copper foil of the present invention provided on the release layer with the roughened surface facing outward. It becomes 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 layer (typically a foil) that supports the roughened copper foil to improve its handling properties. Examples of the carrier include aluminum foil, copper foil, resin film and glass plate whose surface is metal-coated with copper or the like, and copper foil is preferred. The copper foil may be either a rolled copper foil or an electrolytic copper foil. The thickness of the carrier is typically 200 μm or less, preferably 12 μm or more and 35 μm or less.

The surface of the carrier on the release layer side preferably has a ten-point surface roughness Rz of 0.5 μm or more and 1.5 μm or less, more preferably 0.6 μm or more and 1.0 μm or less. Rz can be determined according to JIS B 0601-1994. By imparting such a ten-point surface roughness Rz to the release layer side surface of the carrier, a desirable surface profile is imparted to the roughened copper foil of the present invention produced thereon via the release layer. can be made easier.

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. The carrier may be brought into contact with the release layer component-containing solution by immersion in the release layer component-containing solution, spraying the release layer component-containing solution, or flowing the release layer component-containing solution. 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.

As the roughened copper foil, the above-described roughened copper foil of the present invention is used. The roughening treatment of the present invention is roughening using copper particles, but as a procedure, first, a copper layer is formed as a copper foil on the surface of the release layer, and then at least roughening may be performed. . The details of roughening are as described above. In addition, the copper foil is preferably configured in the form of an ultra-thin copper foil in order to take advantage of the advantage of the copper foil with a carrier. The thickness of the ultrathin copper foil is preferably 0.1 μm or more and 7 μm or less, more preferably 0.5 μm or more and 5 μm or less, and still more preferably 0.5 μm or more and 3 μm or less.

Other functional layers may be provided between the release layer and the carrier and/or 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 release layer side of the carrier and/or on the release layer side of the roughened copper foil, during hot press molding at high temperatures or for a long time, Possible interdiffusion 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 or carrier-attached 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 or the carrier-attached copper foil. By using the roughened copper foil or carrier-attached copper foil of the present invention, it is possible to provide a copper-clad laminate particularly suitable for the SAP method. The 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, or the carrier-added copper foil of the present invention. and a resin layer provided in close contact with the roughened surface of the roughened copper foil in the carrier-attached copper foil. The roughened copper foil or the carrier-attached copper foil may be provided on one side or both sides of the resin layer. 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 in advance on the roughened copper foil or the carrier-attached copper foil via a primer resin layer that is applied to the roughened surface of the roughened copper foil.

Printed Wiring Board The roughened copper foil or carrier-attached copper foil of the present invention is preferably used for producing printed wiring boards, and particularly preferably for producing printed wiring boards by the semi-additive process (SAP). That is, according to a preferred aspect of the present invention, there is provided a printed wiring board obtained using the above-described roughened copper foil or the above-described carrier-attached copper foil. By using the roughened copper foil or the carrier-attached copper foil of the present invention, in the production of printed wiring boards, sufficient shear strength can be ensured to effectively prevent circuit peeling during the work process, and electroless copper foil can be used. It is possible to provide the laminate with a surface profile that is also excellent in etching properties for plating. Further, by using the roughened copper foil, extremely fine dry film resolution can be realized in the dry film development step in the SAP method. Therefore, it is possible to provide a printed wiring board on which extremely fine circuits are formed. The printed wiring board according to this aspect includes a layer structure in which a resin layer and a copper layer are laminated. In the case of the SAP method, the roughened copper foil of the present invention is removed in step (c) of FIG. 1, so the printed wiring board produced by the SAP method no longer contains the roughened copper foil of the present invention. , only the surface profile transferred from the roughened surface of the roughened copper foil remains. Also, the resin layer is as described above for the copper-clad laminate. In any case, a known layer structure can be adopted for the printed wiring board. Specific examples of printed wiring boards include a single-sided or double-sided printed wiring board formed by bonding a roughened copper foil or a copper foil with a carrier of the present invention to one or both sides of a prepreg to form a cured laminate, and then forming a circuit; A multilayer printed wiring board obtained by multilayering these is mentioned. Other specific examples include flexible printed wiring boards, COF, TAB tapes, etc., in which the roughened copper foil or carrier-attached 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-mentioned resin layer to the roughened copper foil or carrier-coated copper foil of the present invention, and the resin layer is used as an insulating adhesive layer to form the above-described resin-coated copper foil (RCC). After lamination on a printed circuit board, the roughened copper foil is used as all or part of the wiring layer to form a circuit by the modified semi-additive (MSAP) method, the subtractive method, etc. Build-up wiring board and roughening treatment Build-up wiring boards in which circuits are formed by the semi-additive (SAP) method by removing the copper foil, and direct build-up on wafers, in which lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit. mentioned. 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 or carrier-attached copper foil of the present invention is suitable for the SAP method. For example, when the circuit is formed by the SAP method, the configurations shown in FIGS. 1 and 2 can be adopted.

The invention is further illustrated by the following examples.

Examples 1-3
Preparation and evaluation of the carrier-attached copper foil were performed as follows.

(1) Fabrication of Carrier A titanium electrode whose surface was polished with a #2000 buff was prepared as a cathode. Also, a DSA (dimensionally stable anode) was prepared as an anode. Using these electrodes, immersed in a copper sulfate solution with a copper concentration of 80 g / L and a sulfuric acid concentration of 260 g / L, electrolysis was performed at a solution temperature of 45 ° C. and a current density of 55 A / dm ² , and an electrolytic copper foil with a thickness of 18 μm was used as a carrier. obtained as

(2) Formation of release layer The electrode surface side of the pickled carrier was immersed in a CBTA aqueous solution having a CBTA (carboxybenzotriazole) 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. for 30 seconds to adsorb the CBTA component onto the electrode surface of the carrier. Thus, a CBTA layer was formed as an organic peeling layer on the surface of the electrode surface of the carrier.

(3) Formation of Auxiliary Metal Layer The carrier on which the organic peeling layer is formed is immersed in a nickel concentration solution of 20 g/L prepared using nickel sulfate. Under the conditions of No. ² , nickel was deposited on the organic release layer in an amount equivalent to a thickness of 0.001 μm. 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 sulfate solution with a copper concentration of 60 g/L and a sulfuric acid concentration of 200 g/L, and the solution temperature is 50°C and the current density is 5 A/dm ² or more. Electrolysis was performed at 30 A/dm ² or less to form an ultra-thin copper foil with a thickness of 1.2 μm on the auxiliary metal layer.

(5) Roughening Treatment The deposition surface of the ultra-thin copper foil described above was subjected to roughening treatment. This roughening treatment was performed by the following three-stage plating. In the plating process at each stage, a copper sulfate solution having the copper concentration, sulfuric acid concentration, chlorine concentration and 9-phenylacridine (9PA) concentration shown in Table 1 was used, at the liquid temperature shown in Table 1, and the current density shown in Table 2. was electroplated. The energization time in the first and second stages of plating was 4.4 seconds per plating, and the energization time in the third stage of plating was 0.6 seconds. Also, the linear flow velocity of the plating solution to the ultrathin copper foil was set to 0.25 m/s or more and 0.35 m/s or less. Thus, three types of roughened copper foils of Examples 1 to 3 were produced.

(6) Antirust Treatment The surface of the roughened layer of the obtained carrier-attached copper foil was subjected to antirust treatment comprising zinc-nickel alloy plating treatment and chromate treatment. First, using an electrolytic solution with a zinc concentration of 0.2 g / L, a nickel concentration of 2 g / L, and a potassium pyrophosphate concentration of 300 g / L, the roughening treatment layer was formed under the conditions of a liquid temperature of 40 ° C. and a current density of 0.5 A / dm ² . And the surface of the carrier was plated with a zinc-nickel alloy. Next, the zinc-nickel alloy plated surface was subjected to chromate treatment using a 1 g/L chromic acid aqueous solution under the conditions of pH 11, liquid temperature 25° C., and current density 1 A/dm ² .

(7) Silane coupling agent treatment An aqueous solution containing 3 g/L of 3-aminopropyltrimethoxysilane is adsorbed on the surface of the copper foil with a carrier on the copper foil side, and the silane coupling agent is treated by evaporating water with an electric heater. processed. At this time, the carrier side was not treated with the silane coupling agent.

(8) Evaluation of Roughened Copper Foil Surface Various characteristics of the surface profile of the obtained roughened copper foil were evaluated as follows.

(8-1) Observation of roughened particles A cross-sectional image of the resulting roughened copper foil was obtained, and the ^average value of the ratio L / S and the number of roughened particles per 10 μm of the roughened copper foil were calculated as follows. I asked for it.

(8-1-1) Acquisition of cross-sectional image FIB-SEM device (manufactured by SII Nanotechnology Co., Ltd., SMI3200SE) is used to perform FIB (Focused Ion Beam) processing from the surface of the roughened copper foil to remove copper. A cross-sectional image was obtained by preparing a cross-section parallel to the thickness direction of the foil and observing this cross-section with an SEM (magnification: 36000 times) from a direction of 60° with respect to the roughened surface.

(8-1-2) Calculation of ratio L ² /S A cross-sectional image corresponding to a length of 10 μm of the roughened copper foil was loaded into the image analysis software Image-Pro Plus 5.1J (manufactured by Media Cybernetics, Inc.), and this Roughening particles in the cross section were extracted one by one using the function "free curve AO" of the analysis software. After extracting all the roughened particles contained in the cross-sectional image, the contrast was adjusted so that the inside of the roughened particles was white. Then, using the function "count / size" of the analysis software, after automatically recognizing the roughening particles changed to a bright color, the measurement function measures the perimeter length L and area S of each roughening particle, The ratio L ² /S was calculated. The above operation was performed for three different fields of view for each example, and the average value of the ratio L ² /S in all the observed roughened particles was adopted as the average value of the ratio L ² /S of the sample.

(8-1-3) Number of Roughened Particles The number of roughened particles in the visual field and the width of the visual field were measured on the cross-sectional image, and converted to the number per 10 μm length. Three different fields of view were measured for each example, and the average value was adopted as the number of roughened particles per 10 µm length in the sample.

(8-2) Measurement of ten-point average roughness Rz Observing the roughened surface using a laser microscope (manufactured by Keyence Corporation, VK-9510) equipped with a 150x objective lens, a field of view of 6550.11 μm ² got the image. Ten areas of 10 μm×10 μm were arbitrarily selected from the obtained visual field image without overlapping each other, and the ten-point average roughness Rz was measured according to JIS B 0601-1994. The average value of Rz at 10 locations was adopted as the Rz of the sample.

(9) Production of copper-clad laminate A copper-clad laminate was produced using a copper foil with a carrier. First, on the surface of the inner layer substrate, a roughened copper foil with a carrier was laminated via a prepreg (GHPL-830NSF, thickness 0.1 mm, manufactured by Mitsubishi Gas Chemical Co., Ltd.), pressure 4.0 MPa, temperature After thermocompression bonding at 220° C. for 90 minutes, the carrier was peeled off to produce a copper-clad laminate.

(10) Production of Laminate for SAP Evaluation Next, after all the copper foil on the surface was removed with a sulfuric acid-hydrogen peroxide-based etchant, degreasing, addition of a Pd-based catalyst, and activation treatment were performed. Electroless copper plating (thickness: 1 μm) was applied to the activated surface to obtain a laminate immediately before a dry film was laminated in the SAP method (hereinafter referred to as a laminate for SAP evaluation). These steps were carried out according to the known conditions of the SAP method.

(11) Evaluation of SAP Evaluation Laminate Various properties of the SAP evaluation laminate obtained above were evaluated as follows.

<Plating circuit adhesion (shear strength)>
A dry film was laminated on the laminate for SAP evaluation, 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 electroless copper plating was removed with a sulfuric acid-hydrogen peroxide-based etchant to prepare a circuit sample for shear strength measurement having a height of 15 μm, a width of 10 μm, and a length of 150 μm. Using a bonding strength tester (4000Plus Bondtester, manufactured by Nordson DAGE), the shear strength when the circuit sample for shear strength measurement was pushed down from the side was measured. 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 applying the circuit 136, a lateral force was applied to the side surface of the circuit 136 to push it down. At this time, the test type was a destructive test, and the measurement was performed under the conditions of a test height of 10 μm, a descent speed of 0.050 mm/s, a test speed of 100.0 μm/s, a tool movement of 0.05 mm, and a rupture recognition point of 10%. .

<Etching property>
The laminate for SAP evaluation was etched with a sulfuric acid-hydrogen peroxide-based etchant by 0.2 μm, and the amount (depth) until the copper on the surface was completely removed was measured. This measurement was performed by checking with an optical microscope (500 times). More specifically, the presence or absence of copper was repeatedly checked with an optical microscope every time etching was performed by 0.2 μm, and the value (μm) obtained by (the number of times of etching)×0.2 μm was used as an etchability index. For example, an etchability of 1.2 μm means that after 6 etchings of 0.2 μm, residual copper was no longer detectable with an optical microscope (i.e., 0.2 μm×6 times=1.2 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. In other words, the smaller this value, the better the etchability.

<Dry film resolution (minimum L/S)>
A dry film with a thickness of 25 μm was laminated on the surface of the laminate for SAP evaluation, and exposure and development were performed using a mask in which a pattern with a line/space (L/S) of 2 μm/2 μm to 15 μm/15 μm was formed. . The exposure dose at this time was 125 mJ. The surface of the sample after development is observed with an optical microscope (magnification: 500 times), and the smallest (i.e., the finest) L/S among L/S at which development can be performed without problems is adopted as an index of dry film resolution. did. For example, the minimum L/S=10 μm/10 μm, which is an index for evaluation of dry film resolution, means that L/S=15 μm/15 μm to 10 μm/10 μm can be resolved without problems. For example, when the resolution was successful, a clear contrast was observed between the dry film patterns, whereas when the resolution was not performed satisfactorily, darkened areas were observed between the dry film patterns. no contrast is observed.

Results Evaluation results obtained in Examples 1 to 3 are as shown in Table 3.

Claims (8)

A roughened copper foil having a roughened surface on at least one side, the roughened surface comprising a plurality of roughened particles,
The average value of the ratio L ² /S of the square of the peripheral length L (μm) of the roughened particles to the area S (μm ² ) of the roughened particles in the cross section of the roughened copper foil having a length of 10 μm is 16 30 or less, and the roughened surface has a ten-point average roughness Rz of 0.7 μm or more and 1.7 μm or less. The roughened copper foil according to claim ¹ , wherein the ratio L2/S is 19 or more and 27 or less. The roughening treated copper foil according to claim 1 or 2, wherein the number of said roughening particles in a cross section of said roughening treated copper foil having a length of 10 µm is 20 or more and 70 or less. The roughened copper foil according to any one of claims 1 to 3, which is used for transferring an uneven shape to an insulating resin layer for printed wiring boards. The roughened copper foil according to any one of claims 1 to 4, which is used for producing a printed wiring board by a semi-additive method (SAP). A carrier, a release layer provided on the carrier, and the roughened copper foil according to any one of claims 1 to 5 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 5 or the carrier-attached copper foil according to claim 6. A method for producing a printed wiring board, which comprises producing a printed wiring board using the roughened copper foil according to any one of claims 1 to 5 or the copper foil with a carrier according to claim 6. .

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