Copper foil with carrier, copper-clad laminate, and printed circuit board

Abstract

Provided is a copper foil with a carrier, with which excellent laser processability can be achieved. This copper foil with a carrier is provided with a carrier, a release layer, and an ultrathin copper foil in said order, wherein copper crystal grains that are present on the release-layer-side surface of the ultrathin copper foil have a plane size S1 of 50 nm to 600 nm as measured using an electron backscatter diffraction (EBSD) method.

Description

[Technical Field]

[0001] This invention relates to copper foil with a carrier, copper-clad laminates, and printed circuit boards. [Background technology]

[0002] In recent years, multi-layer printed circuit boards (PCBs) have become widespread in order to increase the mounting density and reduce the size of the PCBs. Such multi-layer PCBs are used in many portable electronic devices for the purpose of reducing weight and size.

[0003] In the manufacture of such multilayer printed circuit boards, a widely used method involves forming via holes in a laminate, where an inner layer circuit board and an outer layer copper foil are laminated with an insulating layer in between, using laser processing, and then connecting the layers by filling plating. In recent years, direct laser drilling, which involves directly irradiating an ultrathin copper foil (outer layer copper foil) with a laser to form via holes, has become increasingly common in laser processing (see, for example, Patent Document 1 (Japanese Patent Publication No. 11-346060)).

[0004] In this regard, a technique is known for controlling the cross-sectional size of copper crystal grains constituting an ultrathin copper foil to a predetermined value or less in order to improve the laser processability of the ultrathin copper foil. For example, Patent Document 2 (Japanese Patent Application Publication No. 2017-133105) discloses a carrier-attached copper foil in which the average crystal grain size when the cross-sectional image of the ultrathin copper layer is observed with FIB-SIM is controlled to 0.5 μm or less, thereby improving laser drilling and etching properties. Furthermore, Patent Document 3 (Japanese Patent No. 6158573) also discloses a carrier-attached copper foil in which the thickness accuracy of the ultrathin copper layer measured by the gravimetric thickness method is 3.0% or less, and the average crystal grain size when the cross-sectional image of the ultrathin copper layer is observed with FIB-SIM is controlled to 0.5 μm or less, in order to improve laser drilling properties, etc. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-346060 [Patent Document 2] Japanese Patent Publication No. 2017-133105 [Patent Document 3] Patent No. 6158573 [Overview of the Initiative]

[0006] In recent years, printed circuit boards have become more highly integrated, and the miniaturization of wiring and the reduction in via diameter have progressed further. Therefore, there is a growing demand for improved laser processability (via processability) in ultra-thin copper foil. However, the laser processability of ultra-thin copper foil in conventional carrier-attached copper foil is not always sufficient, and there is still room for improvement.

[0007] The present inventors have now found that in a carrier-equipped copper foil comprising a carrier, a release layer, and an ultrathin copper foil in that order, excellent laser processability can be achieved by controlling the planar size of the copper crystal grains present on the release layer side of the ultrathin copper foil within a predetermined range.

[0008] Therefore, the object of the present invention is to provide a carrier-attached copper foil that can achieve excellent laser processability.

[0009] According to one aspect of the present invention, a copper foil with a carrier comprises a carrier, a release layer, and an ultrathin copper foil in this order, A carrier-attached copper foil is provided, wherein the planar size S1 of copper crystal grains present on the surface of the ultrathin copper foil facing the delamination layer, as measured by electron beam backscatter diffraction (EBSD), is between 50 nm and 600 nm.

[0010] According to another aspect of the present invention, a copper-clad laminate comprising a carrier-attached copper foil having a carrier, a release layer, and an ultrathin copper foil in that order, and a resin layer provided on the surface of the ultrathin copper foil of the carrier-attached copper foil, There is provided a copper-clad laminate in which the planar size S1 of copper crystal grains present on the surface on the release layer side of the ultra-thin copper foil, measured by electron backscatter diffraction (EBSD), is 50 nm or more and 600 nm or less.

[0011] According to still another aspect of the present invention, there is provided a printed wiring board provided with the carrier-attached copper foil.

[0012] According to still another aspect of the present invention, there is provided a method for manufacturing a printed wiring board, which comprises manufacturing a printed wiring board using the carrier-attached copper foil.

Brief Description of Drawings

[0013] [Figure 1] It is a schematic cross-sectional view of a laminate produced using the carrier-attached copper foil according to the present invention. [Figure 2] It is a schematic cross-sectional view for explaining the thickness of the ultra-thin copper foil in the carrier-attached copper foil according to the present invention.

Embodiments for Carrying Out the Invention

[0014] Copper foil with carrier The carrier-attached copper foil according to the present invention includes a carrier, a release layer, and an ultra-thin copper foil in this order. In this carrier-attached copper foil, the planar size S1 of copper crystal grains present on the surface on the release layer side of the ultra-thin copper foil, measured by electron backscatter diffraction (EBSD), is 50 nm or more and 600 nm or less. By controlling the planar size of the copper crystal grains present on the surface on the release layer side of the ultra-thin copper foil within a predetermined range in this way, excellent laser processing properties can be realized.

[0015] Here, a schematic cross-sectional view of a laminate fabricated using the copper foil with carrier according to the present invention is shown in FIG. 1. The laminate 18 shown in FIG. 1 includes an ultra-thin copper foil 12 derived from the copper foil with carrier of the present invention and a resin layer 16. Further, roughening particles 14 are attached, if desired, to the surface of the ultra-thin copper foil 12 on the resin layer 16 side. The surface of the laminate 18 on the ultra-thin copper foil 12 side (i.e., the surface opposite to the resin layer 16) is the surface irradiated with a laser L (e.g., a carbon dioxide laser) during laser processing, and corresponds to the surface of the ultra-thin copper foil 12 on the release layer side in the copper foil with carrier. On the other hand, the surface of the ultra-thin copper foil 12 in the laminate 18 on the resin layer 16 side (i.e., the surface opposite to the laser L irradiation surface) corresponds to the surface of the ultra-thin copper foil 12 in the copper foil with carrier opposite to the release layer (if present, the surface on the roughening particles 14 side).

[0016] The mechanism by which excellent laser processing properties can be achieved with the copper foil with carrier of the present invention is not necessarily clear, but for example, the following can be mentioned. That is, in order to easily form vias in the ultra-thin copper foil by laser processing, it is necessary to suppress the diffusion of heat and raise the temperature of the ultra-thin copper foil in a short time. In this regard, by reducing the crystal size of the copper crystal grains constituting the ultra-thin copper foil, the number of grain boundaries per unit area increases, hindering the movement of heat, so it is considered that the ultra-thin copper foil is likely to heat up. In particular, as a result of the study by the present inventors, as shown in FIG. 1, it was found that controlling the planar size S1 of the copper crystal grains G1 present on the laser L irradiation surface (x-y plane) of the ultra-thin copper foil 12 is effective for performing finer via processing. And it was found that excellent laser processing properties can be achieved by setting the planar size S1 of the copper crystal grains G1 present on the surface of the ultra-thin copper foil 12 on the release layer side within the above-mentioned predetermined range in the copper foil with carrier. On the other hand, in the conventional copper foil with carrier, since only the crystal size in the cross-sectional direction (z-axis direction) of the ultra-thin copper foil was controlled, as described above, the laser processing properties of the ultra-thin copper foil were not necessarily sufficient.

[0017] Therefore, the carrier-attached copper foil has a planar size S1 of copper crystal grains G1 present on the release layer side of the ultrathin copper foil 12, as measured by EBSD, which is 50 nm to 600 nm, preferably 70 nm to 600 nm, more preferably 80 nm to 400 nm, and even more preferably 80 nm to 300 nm. Note that the crystal size of the copper crystal grains constituting the ultrathin copper foil 12 may change due to recrystallization caused by hot pressing when bonding with the resin. In this regard, the planar size S1 refers to the planar crystal size (average crystal grain size) after bonding the carrier-attached copper foil to the resin. Specifically, the planar size S1 is the value obtained when the surface of the laminate 18 on the ultrathin copper foil 12 side (i.e., the surface of the ultrathin copper foil 12 on the carrier-attached copper foil) is analyzed by EBSD after pressing a resin sheet (e.g., prepreg) onto the surface of the ultrathin copper foil 12 side of the carrier-attached copper foil at 220°C and a pressure of 4.0 MPa for 90 minutes to form a resin layer 16, and then peeling off the carrier together with the release layer to form a laminate 18 having the ultrathin copper foil 12 and the resin layer 16 as shown in Figure 1. The planar size S1 can preferably be calculated according to the procedure shown in the evaluation of the example (8b) described later. Note that the scanning electron microscope measurement conditions shown in the example may be changed as appropriate depending on the size of the crystal grains, such as the observation magnification, measurement area, current value and step size.

[0018] The carrier-attached copper foil preferably has a cross-sectional size S2 of copper crystal grains constituting the ultrathin copper foil 12, measured by EBSD, of 200 nm to 600 nm, more preferably 300 nm to 400 nm, and even more preferably 350 nm to 400 nm. That is, in order to efficiently form vias by laser processing, a certain amount of heat transfer in the cross-sectional direction (z-axis direction) of the ultrathin copper foil 12 is necessary. On the other hand, in order to avoid excessive heat diffusion, it is preferable that the crystal size in the cross-sectional direction (z-axis direction) of the copper crystal grains be small. For this reason, by setting the cross-sectional size S2 of the copper crystal grains constituting the ultrathin copper foil 12 within the above range, the laser processability of the ultrathin copper foil can be further improved. Furthermore, the cross-sectional size S2 refers to the cross-sectional crystal size (average crystal grain size) after the carrier-attached copper foil is bonded to the resin. Specifically, the cross-sectional size S2 is the value obtained by analyzing the cross-section in the thickness direction of the ultrathin copper foil 12 in the laminate 18 by electron beam backscatter diffraction (EBSD) after the laminate 18 has been fabricated under the same conditions as for calculating the planar size S1. The calculation of the cross-sectional size S2 can preferably be carried out according to the procedure shown in the evaluation of the example (8d) described later.

[0019] The copper foil with carrier preferably has a ratio of the cross-sectional size S2 to the planar size S1, S2 / S1, of 0.7 to 6.0, more preferably 1.0 to 5.0, and even more preferably 1.7 to 3.0. This allows for a good balance between the heating of the ultrathin copper foil and heat transfer in the cross-sectional direction during laser L irradiation, further improving laser processability.

[0020] In the carrier-attached copper foil, the planar size S3 of the copper crystal grains G3 present on the surface of the ultrathin copper foil 12 opposite to the release layer (the surface on the roughened particle 14 side, if present), as measured by EBSD, is preferably 100 nm to 600 nm, more preferably 100 nm to 500 nm, even more preferably 100 nm to 400 nm, even more preferably 100 nm to 300 nm, particularly preferably 100 nm to 200 nm, and most preferably 100 nm to 150 nm. In other words, as the thickness of the ultrathin copper foil 12 tends to increase, the crystal grains tend to become larger, and it is desirable that the crystals do not become unnecessarily coarse. For this reason, as shown in Figure 1, it is desirable that the planar size S3 of the copper crystal grains G3 constituting the surface of the ultrathin copper foil 12 on the resin layer 16 side (i.e., the surface opposite to the laser L irradiation surface, and the surface of the carrier-attached copper foil opposite to the release layer) is also small. Therefore, in the carrier-attached copper foil, by setting the planar size S3 of the copper crystal grains G3 present on the side of the ultrathin copper foil 12 opposite to the release layer to the above range, the ultrathin copper foil 12 can be heated more effectively when irradiated with the laser L, and the laser processability can be further improved. Furthermore, the planar size S3 refers to the planar crystal size (average crystal grain size) after the carrier-attached copper foil is bonded to the resin. Specifically, the planar size S3 is the value obtained when the back surface of the ultrathin copper foil 12 in the laminate 18 is analyzed by EBSD after the laminate 18 is fabricated under the same conditions as the calculation of the planar size S1 above. Here, the back surface of the ultrathin copper foil 12 refers to the surface located 0.1 μm shallower than the thickness of the ultrathin copper foil 12, as described later, in the depth direction from the surface of the laminate 18 on the ultrathin copper foil 12 side. The calculation of the planar size S3 can preferably be performed according to the procedure shown in the evaluation of the example (8c) described later.

[0021] The thickness of the ultra-thin copper foil 12 is preferably 2.0 μm or less, more preferably 0.3 μm to 1.2 μm, even more preferably 0.3 μm to 1.0 μm, and particularly preferably 0.3 μm to 0.8 μm. This makes it easier to control the planar size S1, cross-sectional size S2, and planar size S3 within the above predetermined ranges, and as a result, the laser processability can be improved even more effectively. If the carrier-attached copper foil further comprises a roughening layer composed of a plurality of roughening particles 14, the thickness of the ultra-thin copper foil 12 shall not include the thickness of this roughening layer. The thickness of the ultra-thin copper foil 12 can preferably be measured, for example, by using either of the following methods (i) or (ii) after fabricating a laminate 18 under the same conditions as for calculating the planar size S1. (i) Observe the cross-section of the laminate 18 using a focused ion beam scanning electron microscope (FIB-SEM). In the analysis of this cross-section, as shown in Figure 2, draw a line A that passes through the deepest recess 14a of the roughened particles and is parallel to the average plane of the ultrathin copper foil surface 12a. Then, draw a line segment B perpendicular to line A from the deepest recess 14a of the roughened particles toward the ultrathin copper foil surface 12a. Calculate the distance until this line segment B touches the ultrathin copper foil surface 12a and determine the thickness of the ultrathin copper foil 12. (ii) Planar milling is performed on the ultrathin copper foil 12 side of the laminate 18 using a cross-section polisher (CP). Planar milling is continued, and the milling depth at which the resin layer 16 begins to be exposed in a part of the laminate 18 is calculated from the milling rate measured in advance and is set as the thickness of the ultrathin copper foil 12. Whether or not the resin layer 16 is exposed can be determined by observing the processed surface of the laminate 18 at low magnification (for example, about 1000 times) using a scanning electron microscope (SEM).

[0022] Optionally, the surface of the ultrathin copper foil 12 may be roughened to form a roughened layer. By providing a roughened layer on the ultrathin copper foil 12, adhesion with the resin layer 16 during the manufacture of copper-clad laminates or printed circuit boards can be improved. This roughened layer comprises a plurality of roughened particles 14 (bumps), and it is preferable that each of these roughened particles 14 is made of copper particles. The copper particles may be made of metallic copper or a copper alloy. The roughening treatment to form the roughened surface can preferably be carried out by forming roughened particles 14 of copper or a copper alloy on the ultrathin copper foil 12. For example, it is preferable that the roughening treatment be carried out according to a plating method that includes at least two plating steps, including a burn plating step for depositing and adhering fine copper particles onto the ultrathin copper foil 12 and an overlay plating step to prevent the detachment of these fine copper particles.

[0023] Optionally, the surface of the ultrathin copper foil 12 may be treated with a rust-preventive coating to form a rust-preventive coating layer. The rust-preventive coating preferably includes a zinc plating treatment. The zinc plating treatment may be either zinc plating or zinc alloy plating, with zinc-nickel alloy plating being particularly preferred. The zinc-nickel alloy plating treatment may include at least Ni and Zn, and may further include 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 by mass ratio, more preferably 2 to 7, and even more preferably 2.7 to 4. Furthermore, the rust-preventive coating preferably includes a chromate treatment, and this chromate treatment is more preferably performed on the surface of the zinc-containing plating after the zinc plating treatment. This further improves rust resistance. A particularly preferred rust-preventive coating is a combination of zinc-nickel alloy plating and subsequent chromate treatment.

[0024] If desired, the surface of the ultrathin copper foil 12 may be treated with a silane coupling agent to form a silane coupling agent layer. This can improve moisture resistance, chemical resistance, and adhesion to adhesives, etc. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, applying it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane; amino-functional silane coupling agents such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane; olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane; acrylic-functional silane coupling agents such as 3-methacryloxypropyltrimethoxysilane; imidazole-functional silane coupling agents such as imidazolesilane; and triazine-functional silane coupling agents such as triazinesilane.

[0025] Therefore, it is preferable that the carrier-attached copper foil further comprises at least one layer selected from the group consisting of a roughening layer composed of a plurality of roughening particles 14, a rust-preventive treatment layer, and a silane coupling agent layer on the ultrathin copper foil 12. For example, when the carrier-attached copper foil further comprises a roughening layer, a rust-preventive treatment layer, and a silane coupling agent layer, the order in which these layers are composed is not particularly limited, but it is preferable that the roughening layer, rust-preventive treatment layer, and silane coupling agent layer are laminated on the ultrathin copper foil 12 in this order.

[0026] Carrier-supported copper foil includes a carrier. The carrier is a support for the ultrathin copper foil to improve its handling properties, and a typical carrier includes a metal layer. Examples of such carriers include aluminum foil, copper foil, stainless steel (SUS) foil, resin films or glass with a metal coating on the surface of copper or the like, with copper foil being preferred. The copper foil may be either rolled copper foil or electrolytic copper foil, but electrolytic copper foil is preferred. The thickness of the carrier is typically 250 μm or less, preferably 7 μm to 200 μm.

[0027] A copper foil with a carrier is provided with a release layer on the carrier. The release layer is a layer that weakens the peel strength of the carrier, ensures the stability of that strength, and further suppresses mutual diffusion that may occur between the carrier and the copper foil during high-temperature press molding. The release layer is generally formed on one side of the carrier, but it 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, and carboxylic acids. Examples of nitrogen-containing organic compounds include triazole compounds and imidazole compounds, among which triazole compounds are preferred because they tend to have stable release properties. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N',N'-bis(benzotriazolylmethyl)urea, 1H-1,2,4-triazole, and 3-amino-1H-1,2,4-triazole. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, and 2-benzimidazole thiol. Examples of carboxylic acids include monocarboxylic acids and dicarboxylic acids. On the other hand, examples of inorganic components used in the inorganic exfoliation layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and chromate-treated films. The thickness of the exfoliation layer is typically 1 nm to 1 μm, preferably 5 nm to 500 nm.

[0028] Other functional layers may be provided between the release layer and the carrier and / or the ultrathin copper foil 12. An example of such other functional layer is an auxiliary metal layer. The auxiliary metal layer is preferably made of nickel and / or cobalt. By forming such an auxiliary metal layer on the surface side of the carrier and / or the surface side of the ultrathin copper foil 12, mutual diffusion that may occur between the carrier and the ultrathin copper foil 12 during hot press molding at high temperatures or for long periods of time can be further suppressed, and the stability of the carrier's peel strength can be ensured. The thickness of the auxiliary metal layer is preferably 0.001 μm or more and 3 μm or less.

[0029] Manufacturing method for copper foil with carrier The carrier-attached copper foil of the present invention can be manufactured by (1) preparing a carrier, (2) forming a release layer on the carrier, and (3) forming an ultrathin copper foil on the release layer. An example of a preferred manufacturing method for the carrier-attached copper foil according to the present invention is described below.

[0030] (1) Career preparation First, a carrier is prepared to serve as the support. Typical carriers include a metal layer. Examples of such carriers, as mentioned above, include aluminum foil, copper foil, stainless steel (SUS) foil, resin films or glass with a metal coating on the surface of copper or the like, and preferably copper foil. The copper foil may be either rolled copper foil or electrolytic copper foil, but electrolytic copper foil is preferred. The thickness of the carrier is typically 250 μm or less, preferably 7 μm to 200 μm.

[0031] The surface of the carrier facing the release layer is preferably smooth. That is, in the manufacturing process of copper foil with a carrier, an ultrathin copper foil 12 is formed on the surface of the carrier facing the release layer. Therefore, by making the surface of the carrier facing the release layer smooth, the outer surface of the ultrathin copper foil 12 can also be made smooth, making it easier to make the crystal growth surface of the ultrathin copper foil 12 uniform. As a result, it becomes easier to obtain an ultrathin copper foil composed of copper crystal grains having a desired crystal size. To make the surface of the carrier facing the release layer smooth, for example, the surface roughness can be adjusted by polishing the surface of the cathode used when electrolytically manufacturing the carrier with a buff of a predetermined grit. That is, the surface profile of the cathode thus adjusted is transferred to the electrode surface of the carrier, and by forming an ultrathin copper foil on this electrode surface of the carrier via the release layer, it becomes easier to form an ultrathin copper foil composed of copper crystal grains of the predetermined crystal size. The preferred buff grit is #1,000 to #3,500, and more preferably #1,000 to #2,500. Furthermore, from the viewpoint of making it easier to control the crystal size of the copper crystal grains constituting the ultrathin copper foil within a desired range, the deposited surface of the carrier produced by electrolytic foil manufacturing using an electrolyte containing additives may be used as the surface of the carrier's release layer.

[0032] (2) Formation of the delamination layer A release layer is formed on the carrier. The release layer may be either an organic or an inorganic release layer. Preferred examples of the organic and inorganic release layers are as described above. The release layer can be formed by contacting a solution containing the release layer component with at least one surface of the carrier and fixing the release layer component to the surface of the carrier. When contacting the carrier with the solution containing the release layer component, this contact can be performed by immersion in the solution, spraying the solution, or letting the solution flow down. In addition, methods for forming a film of the release layer component by vapor deposition or sputtering can also be employed. Furthermore, the release layer component can be fixed to the carrier surface by adsorption or drying of the solution containing the release layer component, or by electrodeposition of the release layer component in the solution. The thickness of the release layer is typically 1 nm to 1 μm, preferably 5 nm to 500 nm.

[0033] (3) Formation of ultra-thin copper foil An ultrathin copper foil 12 is formed on the release layer. For example, the ultrathin copper foil 12 may be formed by a wet film formation method such as electroless copper plating and electrolytic copper plating, a dry film formation method such as sputtering and chemical vapor deposition, or a combination thereof. Preferably, the ultrathin copper foil 12 is formed by electrolytic copper plating. In particular, from the viewpoint of controlling the initial deposition of the ultrathin copper foil and reducing the crystal grain size, it is preferable to set the conditions for electrolytic foil manufacturing of the ultrathin copper foil 12 as follows. Specifically, a sulfuric acid-based copper electrolyte is used, with a copper concentration of 40 g / L to 80 g / L (more preferably 50 g / L to 70 g / L), a sulfuric acid concentration of 180 g / L to 260 g / L (more preferably 200 g / L to 250 g / L), and a carboxybenzotriazole (CBTA) additive concentration adjusted to more than 0 ppm and less than 200 ppm. A dimensionally stable anode (DSA) is used as the anode, with a liquid temperature of 35°C to 60°C (more preferably 40°C to 55°C), and a current density of 3 A / dm². 2 Above 60A / dm 2 (more preferably 5A / dm 2 More than 35A / dm 2 More preferably 6 A / dm 2 More than 30A / dm 2 By electrolysis as described below, the desired electrolytic copper foil can be readily obtained. The CBTA concentration in the electrolyte is more preferably 0.1 ppm to 100 ppm, even more preferably 0.1 ppm to 50 ppm, particularly preferably 0.1 ppm to 30 ppm, and most preferably 0.1 ppm to 10 ppm. By adding carboxybenzotriazole (CBTA) as an additive to the electrolyte and controlling the current density, etc., within the above range during electrolytic foil manufacturing, it becomes easier to form an ultrathin copper foil 12 composed of copper crystal grains having the predetermined crystal size.

[0034] If desired, the surface of the ultrathin copper foil may be subjected to a roughening treatment, a rust-preventive treatment, and / or a silane coupling agent treatment to form a roughened layer, a rust-preventive treatment layer, and / or a silane coupling agent layer consisting of multiple roughened particles. These treatments are as described above.

[0035] Copper-clad laminate The carrier-equipped copper foil of the present invention is preferably used in the manufacture of copper-clad laminates for printed circuit boards. That is, according to a preferred embodiment of the present invention, a copper-clad laminate equipped with the carrier-equipped copper foil is provided. The copper-clad laminate comprises a carrier-equipped copper foil having a carrier, a release layer, and an ultrathin copper foil in that order, and a resin layer provided on the surface of the ultrathin copper foil of the carrier-equipped copper foil (the surface of the ultrathin copper foil opposite to the release layer). In this copper-clad laminate, the planar size S1 of copper crystal grains present on the surface of the ultrathin copper foil on the release layer side (the surface opposite to the resin layer), as measured by electron beam backscatter diffraction (EBSD), is 50 nm or more and 600 nm or less. The preferred embodiment of the carrier-equipped copper foil described above also applies to the carrier-equipped copper foil provided in the copper-clad laminate. The carrier-equipped copper foil may be provided on one side of the resin layer or on both sides. The resin layer comprises a resin, preferably an insulating resin. The resin layer is preferably a prepreg and / or a resin sheet. A prepreg is a general term for a composite material in which a synthetic resin is impregnated into a substrate such as a synthetic resin plate, glass plate, glass woven fabric, glass nonwoven fabric, or paper. Preferred examples of insulating resins include epoxy resin, cyanate resin, bismaleimide triazine resin (BT resin), polyphenylene ether resin, and phenolic resin. Examples of insulating resins that constitute a resin sheet include epoxy resin, polyimide resin, and polyester resin. The resin layer may also contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation. The thickness of the resin layer is not particularly limited, but is preferably 1 μm to 1000 μm, more preferably 2 μm to 400 μm, and even more preferably 3 μm to 200 μm. The resin layer may be composed of multiple layers. The resin layer, such as a prepreg and / or a resin sheet, may be provided on a carrier-attached copper foil via a primer resin layer that is pre-applied to the surface of an ultrathin copper foil.

[0036] Printed circuit board The carrier-equipped copper foil of the present invention is preferably used in the manufacture of printed circuit boards. That is, according to a preferred embodiment of the present invention, a printed circuit board equipped with the carrier-equipped copper foil, or a method for manufacturing the same, is provided. The printed circuit board according to this embodiment includes a layer structure in which a resin layer and a copper layer are laminated in that order. The resin layer is as described above with respect to copper-clad laminates. In any case, any known layer structure can be used for the printed circuit board. Specific examples of printed circuit boards include single-sided or double-sided printed circuit boards in which circuits are formed on a laminate formed by bonding the ultra-thin copper foil of the present invention to one or both sides of a prepreg and curing it, and multilayer printed circuit boards made by layering these. Other specific examples include flexible printed circuit boards, COF, TAB tapes, etc., in which circuits are formed by forming the ultra-thin copper foil of the present invention on a resin film. Further specific examples include a build-up wiring board in which a resin-coated copper foil (RCC) is formed by applying the above-mentioned resin layer to the ultrathin copper foil of the present invention, the resin layer is laminated onto the above-mentioned printed circuit board as an insulating adhesive layer, and then a circuit is formed using the modified semi-additive method (MSAP), subtractive method, etc., with the ultrathin copper foil as all or part of the wiring layer; a build-up wiring board in which the ultrathin copper foil is removed and a circuit is formed using the semi-additive method (SAP); and a direct build-up on wafer in which the lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit. The carrier-coated copper foil of the present invention can also be preferably used in manufacturing methods using a coreless build-up method in which an insulating resin layer and a conductive layer are alternately laminated without using a so-called core substrate. [Examples]

[0037] The present invention will be further described in detail by the following examples.

[0038] Examples 1-4 and 6-11 A copper foil with a carrier equipped with a roughened copper foil was fabricated and evaluated as follows.

[0039] (1) Career preparation For Examples 1, 3, 4, and 6-11, a copper electrolyte with the composition shown below, a cathode, and a DSA (dimensionally stable anode) as the anode were used, with a solution temperature of 50°C and a current density of 70 A / dm². 2 Electrolysis was performed to obtain an electrolytic copper foil with a thickness of 18 μm as the carrier. At this time, an electrode was used as the cathode, whose surface roughness was adjusted by polishing the surface with a buff of the grit shown in Table 1. <Composition of copper electrolyte> - Copper concentration: 80g / L - Sulfuric acid concentration: 300g / L - Chlorine concentration: 30 mg / L - Glue concentration: 5mg / L

[0040] For Example 2, a sulfuric acid-acidified copper sulfate solution with the following composition was used as the copper electrolyte. An electrode with a surface roughness Ra of 0.20 μm was used as the cathode, and a DSA (dimensionally stable anode) was used as the anode, with a solution temperature of 45°C and a current density of 55 A / dm². 2 Electrolysis was performed to obtain an electrolytic copper foil with a thickness of 18 μm as a carrier. <Composition of sulfuric acid-acidified copper sulfate solution> - Copper concentration: 80g / L - Sulfuric acid concentration: 260g / L - Bis(3-sulfopropyl) disulfide concentration: 30 mg / L - Diallyldimethylammonium chloride polymer concentration: 50 mg / L - Chlorine concentration: 40 mg / L

[0041] (2) Formation of the delamination layer For Examples 1, 3, 4, and 6-11, the electrode surface of the pickled carrier was immersed for 30 seconds at a liquid temperature of 30°C in an aqueous CBTA solution containing 1 g / L carboxybenzotriazole (CBTA), 150 g / L sulfuric acid, and 10 g / L copper, thereby adsorbing the CBTA component onto the electrode surface of the carrier. In this way, a CBTA layer was formed on the electrode surface of the carrier as an organic exfoliation layer. In Example 2, the organic exfoliation layer was formed in the same manner as in Examples 1, 3, 4, and 6-11, except that the CBTA layer was formed by adsorbing the CBTA component onto the precipitated surface instead of the electrode surface of the carrier.

[0042] (3) Formation of auxiliary metal layer The carrier with the organic release layer formed thereon was immersed in a solution containing 20 g / L of nickel concentration prepared using nickel sulfate, at a solution temperature of 45°C, pH 3, and current density of 5 A / dm 2 Under the conditions of, nickel with an adhesion amount equivalent to 0.001 μm in thickness was adhered onto the organic release layer. Thus, a nickel layer was formed as an auxiliary metal layer on the organic release layer.

[0043] (4) Formation of ultra-thin copper foil The carrier with the auxiliary metal layer formed thereon was immersed in a copper solution having the composition shown below, and electrolyzed at a solution temperature of 50°C and a current density of 5 A / dm 2 or more and 40 A / dm 2 or less, to form an ultra-thin copper foil with a predetermined thickness on the auxiliary metal layer. <Composition of the solution> - Copper concentration: 60 g / L - Sulfuric acid concentration: 200 g / L - CBTA concentration: as shown in Table 1.

[0044] (5) Roughening treatment By performing a roughening treatment on the surface of the thus formed ultra-thin copper foil, a roughened copper foil was formed, thereby obtaining a copper foil with a carrier. This roughening treatment consists of a burning plating process for depositing and adhering fine copper particles onto the ultra-thin copper foil, and a covering plating process for preventing the detachment of these fine copper particles. In the burning plating process, 9-phenylacridine (9PA) and chlorine were added to an acidic copper sulfate solution at a solution temperature of 25°C containing 10 g / L of copper concentration and 200 g / L of sulfuric acid concentration, such that the 9PA concentration was 60 ppm and the chlorine concentration was 50 ppm, and the roughening treatment was performed at a current density of 20 A / dm 2 Thereafter, in the covering plating process, electrodeposition was performed under the smoothing plating conditions of a solution temperature of 52°C and a current density of 15 A / dm 2 using an acidic copper sulfate solution containing 70 g / L of copper concentration and 240 g / L of sulfuric acid concentration.

[0045] (6) Rust prevention treatment The roughened surface of the resulting carrier-attached copper foil was subjected to rust prevention treatment consisting of zinc-nickel alloy plating and chromate treatment. First, a solution containing zinc concentration of 1 g / L, nickel concentration of 2 g / L, and potassium pyrophosphate concentration of 80 g / L was used, at a liquid temperature of 40°C and a current density of 0.5 A / dm². 2 Under these conditions, the roughened layer and the carrier surface were plated with a zinc-nickel alloy. Then, an aqueous solution containing 1 g / L of chromic acid was used, with a pH of 12 and a current density of 1 A / dm². 2 Under these conditions, a chromate treatment was performed on a surface that had been plated with a zinc-nickel alloy.

[0046] (7) Silane coupling agent treatment A commercially available aqueous solution containing a silane coupling agent was adsorbed onto the roughened copper foil side of a copper foil with a carrier, and the water was evaporated using an electric heater to perform the silane coupling agent treatment. The carrier side was not treated with the silane coupling agent.

[0047] (8) Evaluation The following evaluations were performed on the various properties of the resulting copper foil with carriers.

[0048] (8a) Fabrication of the laminate A laminate 18, shown in Figure 1, was fabricated using the obtained carrier-attached copper foil as follows. First, a 0.10 mm thick prepreg (Mitsubishi Gas Chemical Co., Ltd., GHPL-830NX-A) was prepared. The obtained carrier-attached copper foil was laminated onto this prepreg so that its roughened surface (the side with the roughened particles 14) was in contact with the prepreg, and a resin layer 16 was formed by pressing at a temperature of 220°C and a pressure of 4.0 MPa for 90 minutes. Subsequently, the carrier was peeled off together with the release layer to obtain a laminate 18 comprising an ultrathin copper foil 12 and a resin layer 16. A cross-sectional observation of this laminate 18 was performed using a focused ion beam scanning electron microscope (FIB-SEM), and the thickness of the ultrathin copper foil 12 (excluding the roughened particles 14) was measured in advance. In the analysis of this cross-section, first, as shown in Figure 2, a line A was drawn that passed through the most recessed part 14a of the roughened particles and was parallel to the average plane of the ultrathin copper foil surface 12a. Next, a line segment B perpendicular to line A was drawn from the deepest recess 14a of the roughened particles toward the surface 12a of the ultrathin copper foil. The distance until this line segment B touched the surface 12a of the ultrathin copper foil was calculated and determined as the thickness of the ultrathin copper foil 12. The thickness of the ultrathin copper foil 12 in each example is shown in Table 1.

[0049] (8b) Measurement of planar crystal size on the surface of ultrathin copper foil Using the laminate 18 obtained in (8a) above, the planar size S1 of copper crystal grains G1 present on the outermost surface of the ultrathin copper foil 12 (i.e., the surface of the ultrathin copper foil 12 on the delamination layer side in the carrier-attached copper foil) was measured as follows. First, the laminate 18 was fixed to an aluminum stub with adhesive, and then carbon paste was applied to the periphery of the laminate 18 to determine the observation position and ensure conductivity. Subsequently, planar milling was performed on the ultrathin copper foil 12 side of the laminate 18 using a cross-section polisher (CP). This planar milling was performed under the conditions of an acceleration voltage of 3kV and an inclination angle of 10°. Then, the surface of the laminate 18 on the ultrathin copper foil 12 side after 5 minutes of planar milling (equivalent to a thickness of 50nm) was used as the outermost surface of the ultrathin copper foil 12, and marking and FIB marker processing were performed.

[0050] The outermost surface of this ultrathin copper foil 12 was observed using an FE gun type scanning electron microscope (Carl Zeiss Corporation, Crossbeam 540) equipped with an EBSD detector (Oxford Instruments, Symmetry). EBSD data was then acquired using EBSD measurement software (Oxford Instruments, AZtec 5.0 HF1), and the obtained EBSD data was converted to OIM format. The measurement conditions for the scanning electron microscope during observation were as follows. <Scanning electron microscope measurement conditions> - Acceleration voltage: 15kV - Step size: 22.9nm -Area width: 5.86μm - Region height: 4.4 μm -Scan Phase: Cu - Sample angle: 70°

[0051] Based on the data converted to the above OIM format, the crystal distribution was measured using crystal diameter calculation software (AMETEK, OIM Analysis v7.3.1 x64), and the planar size S1 (average crystal grain size, the "Grain Size-Average Area" item in the software) of copper crystal grains G1 present on the outermost surface of the ultrathin copper foil 12 was calculated. The results are shown in Table 1. In measuring the crystal distribution, a difference in orientation of 5° or more was considered a crystal grain boundary. However, since the crystal structure of copper is cubic, considering twin grain boundaries, cases falling under (i) or (ii) below were not considered crystal grain boundaries. (i) <111> Twin grain boundaries with a 60° rotational orientation relationship around the axis (ii) <110> Twin grain boundaries with an orientation relationship of 38.9° rotation around the axis

[0052] (8c) Measurement of planar crystal size on the back surface of ultrathin copper foil Next, the planar size S3 of copper crystal grains G3 present on the back surface of the ultrathin copper foil 12 (i.e., the surface opposite to the delamination layer of the ultrathin copper foil 12 in the carrier-attached copper foil) was measured as follows. First, planar milling was performed on the laminate 18 after the planar size S1 measurement in (8b) above, starting from the marking position (outermost surface) of the ultrathin copper foil 12, using a cross-section polisher (CP). This planar milling was continued until the back surface of the ultrathin copper foil 12 was reached. The back surface of the ultrathin copper foil 12 was defined as the surface located 0.1 μm shallower than the thickness of the ultrathin copper foil 12 measured in (8a) above, in the depth direction from the outermost surface of the ultrathin copper foil 12. After that, the planar size S3 (average crystal grain size, the "Grain Size-Average Area" item in the software) of copper crystal grains G3 present on the back surface of the ultrathin copper foil 12 was calculated in the same manner as in (8b) above. The results are shown in Table 1.

[0053] (8d) Measurement of cross-sectional crystal size The cross-sectional size S2 of the copper crystal grains constituting the ultrathin copper foil 12 was measured using the laminate 18 obtained in (8a) above as follows. First, the cross-section was processed from the surface of the laminate 18 on the ultrathin copper foil 12 side toward the thickness direction using a cross-section polisher (CP) under the condition of an acceleration voltage of 5kV. Then, the cross-sectional size S2 (average crystal size, the "Grain Size-Average Area" item in the software) of the copper crystal grains constituting the ultrathin copper foil 12 was calculated in the same manner as in (8b) above, except that the measurement conditions of the scanning electron microscope were changed as follows. The results are shown in Table 1. <Scanning electron microscope measurement conditions> - Acceleration voltage: 10.00kV - Step size: 10nm -Area width: 5.86μm - Region height: 4.4 μm -Scan Phase: Cu - Sample angle: 70°

[0054] (8e) Evaluation of laser processability The laser processability of the laminate 18 obtained in (8a) above was evaluated as follows. First, a carbon dioxide laser was used to laser process the surface of the laminate 18 on the side with the ultrathin copper foil 12, with a beam diameter of 86 μm and a pulse width of 12 μs, to form 121 vias. The formed vias were observed from the ultrathin copper foil 12 side using a metallurgical microscope. At this time, the first 33 holes were not included in the evaluation due to variations, and the remaining 88 holes were observed to see whether the copper on the surface had been removed. The laser power density was set to 1.0 MW / cm². 2 From 0.1 MW / cm² 2 6.5 MW / cm² at intervals 2 The above laser processing and observation were performed after making the necessary changes. Then, among the laser power densities in which the copper on the surface of all 88 holes was removed, the lowest laser power density was used as the processing energy (MW / cm²). 2 The results are shown in Table 1.

[0055] Example 5 (comparison) We used copper foil with a carrier attached, obtained from the market. We evaluated various properties of this copper foil with a carrier attached in the same manner as in Examples 1-4 and 6-11 (evaluations (8a)-(8e)). The results are shown in Table 1.

[0056] [Table 1]

Claims

1. A copper foil with a carrier, comprising a carrier, a release layer, and an ultrathin copper foil in this order, The planar size S of copper crystal grains present on the surface of the ultrathin copper foil facing the delamination layer, as measured by electron beam backscatter diffraction (EBSD). １ A carrier-coated copper foil with a wavelength between 50 nm and 600 nm.

2. The cross-sectional size S of the copper crystal grains constituting the ultrathin copper foil, as measured by electron beam backscatter diffraction (EBSD). ２ The carrier-equipped copper foil according to claim 1, wherein the wavelength is 200 nm or more and 600 nm or less.

3. The aforementioned planar size S １ The cross-sectional size S relative to the above ２ S is the ratio of ２ / S １ The carrier-equipped copper foil according to claim 1 or 2, wherein the coefficient is 0.7 or more and 6.0 or less.

4. The planar size S of copper crystal grains present on the surface of the ultrathin copper foil opposite to the delamination layer, as measured by electron beam backscatter diffraction (EBSD). ３ A carrier-equipped copper foil according to any one of claims 1 to 3, wherein the wavelength is 100 nm or more and 600 nm or less.

5. The carrier-equipped copper foil according to any one of claims 1 to 4, wherein the thickness of the ultrathin copper foil is 2.0 μm or less.

6. The carrier-equipped copper foil according to any one of claims 1 to 5, further comprising on the ultrathin copper foil at least one layer selected from the group consisting of a roughening layer composed of a plurality of roughening particles, a rust-preventive treatment layer, and a silane coupling agent layer.

7. The carrier-equipped copper foil according to any one of claims 1 to 6, wherein the carrier includes a metal layer.

8. The carrier-equipped copper foil according to any one of claims 1 to 7, further comprising an auxiliary metal layer between the release layer and the carrier and / or the ultrathin copper foil.

9. A copper-clad laminate comprising a carrier-attached copper foil having a carrier, a release layer, and an ultrathin copper foil in that order, and a resin layer provided on the surface of the ultrathin copper foil of the carrier-attached copper foil, The planar size S of copper crystal grains present on the surface of the ultrathin copper foil facing the delamination layer, as measured by electron beam backscatter diffraction (EBSD). １ A copper-clad laminate with a wavelength between 50 nm and 600 nm.

10. A printed circuit board comprising a copper foil carrier as described in any one of claims 1 to 8.

11. A method for manufacturing a printed circuit board, characterized by manufacturing a printed circuit board using a carrier-equipped copper foil as described in any one of claims 1 to 8.

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