Methods for manufacturing carrier metal foil, metal laminate, printed circuit board, and printed circuit board.

Abstract

This invention provides a carrier-supported metal foil that can suppress breakage or cracking of the metal foil during operation. The carrier-supported metal foil sequentially comprises a carrier, a release layer, and a metal foil, wherein the tensile strength of the carrier is 50.0 kgf / mm² or higher, and the tensile strength of the metal foil is 50.0 kgf / mm² or higher.

Description

[Technical Field]

[0001] This invention relates to a carrier metal foil, a metal laminate, and a printed circuit board. [Previous Technology]

[0002] Carrier metal foil is widely used as a material for manufacturing printed circuit boards. Typically, carrier metal foil has a structure consisting of a carrier, a release layer, and a metal foil (e.g., an ultra-thin copper foil) in sequence. The carrier metal foil is bonded to an insulating resin substrate (resin layer) such as a glass-epoxy material, a phenolic substrate, or polyimide by hot pressing to form a metal laminate (e.g., a copper laminate), which is then used to manufacture printed circuit boards.

[0003] When a carrier metal foil is hot-pressed at a high temperature (e.g., above 250°C), the peel strength between the carrier and the metal foil increases, making it difficult to peel the carrier off the metal foil. A carrier metal foil is known to address this problem. For example, Patent Document 1 (International Publication No. 2015 / 080052) discloses a carrier copper foil characterized by using an electrolytic copper foil with a tensile strength of 40 kgf / mm² or higher after a heat treatment at 250°C for 60 minutes as the carrier. According to this carrier copper foil, it is possible to suppress the formation of a bonding interface layer between the carrier and the copper foil, and to easily peel the carrier off the copper foil. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2015 / 080052 [Summary of the Invention]

[0005] Furthermore, in recent years, due to efforts to achieve the SDGs (Sustainable Development Goals) and promote carbon neutrality, it is envisioned that the carrier in the carrier-supported metal foil will become thinner to reduce CO2 emissions during manufacturing. However, there are concerns that as the carrier becomes thinner, the risk of breakage or cracking of the metal foil during handling increases. In particular, there is a risk that breakage or cracking of the metal foil during handling could lead to residual metal in the printed circuit board manufacturing process, which requires improvement.

[0006] The inventors have obtained the following insight: for a carrier-supported metal foil, by making the tensile strength of the carrier 50.0 kgf / mm² or more, and the tensile strength of the metal foil also 50.0 kgf / mm² or more, the breakage or cracking of the metal foil during operation can be suppressed.

[0007] Therefore, the object of the present invention is to provide a carrier metal foil that can suppress the breakage or cracking of the metal foil during operation.

[0008] According to the present invention, the following embodiments are provided. [Sample 1] A carrier-supported metal foil, which sequentially comprises a carrier, a release layer, and a metal foil, wherein the tensile strength of the carrier is 50.0 kgf / mm² or more, and the tensile strength of the metal foil is 50.0 kgf / mm² or more. [Sample 2] The carrier-supported metal foil described in Sample 1, wherein after being heated at 250°C for 60 minutes, the tensile strength of the carrier is 45.0 kgf / mm² or more, and / or the tensile strength of the metal foil is 45.0 kgf / mm² or more. [Sample 3] The carrier-supported metal foil described in Sample 1 or 2, wherein both the carrier and the metal foil are copper foils. [Sample 4] The carrier-supported metal foil described in any one of Samples 1 to 3, wherein the thickness of the carrier is 6 μm or more and 18 μm or less. [Sample 5] A carrier metal foil as described in any one of Samples 1 to 4, wherein the thickness of the metal foil is 0.1 μm to 6 μm. [Sample 6] A carrier metal foil as described in any one of Samples 1 to 5, wherein the metal foil further comprises at least one layer selected from the group consisting of a roughening layer containing a plurality of roughening particles, a rust-preventing layer, and a silane coupling agent layer. [Sample 7] A carrier metal foil as described in any one of Samples 1 to 6, wherein an auxiliary metal layer is further provided between the release layer and the carrier and / or the metal foil. [Sample 8] A metal laminate comprising a carrier metal foil as described in any one of Samples 1 to 7. [Sample 9] A printed circuit board comprising a carrier metal foil as described in any one of Samples 1 to 7. [Sample 10] A method for manufacturing a printed circuit board, characterized in that the printed circuit board is manufactured using a carrier metal foil as described in any one of Samples 1 to 7.

Implementation Method

[0010] Carrier-supported metal foil The carrier-supported metal foil of the present invention sequentially comprises a carrier, a release layer, and a metal foil. The tensile strength of the carrier of the carrier-supported metal foil is 50.0 kgf / mm² or higher, and the tensile strength of the metal foil is 50.0 kgf / mm² or higher. As described above, for the carrier-supported metal foil, by making the tensile strength of the carrier 50.0 kgf / mm² or higher, and the tensile strength of the metal foil also 50.0 kgf / mm² or higher, breakage or cracking of the metal foil during operation can be suppressed.

[0011] As described above, the breakage or cracking of the metal foil during operation with a carrier metal foil may lead to abnormalities such as residual metal in the printed circuit board manufacturing process. Here, the mechanism of residual metal caused by the breakage of the metal foil will be explained with reference to FIG1. ​​As shown in FIG1(i), when the carrier metal foil 10 having a carrier 12, a release layer (not shown), and a metal foil 14 is operated, the metal foil 14 may break, forming a fracture portion B. By hot pressing the area layer resin layer 16 (e.g., prepreg) on ​​one side of the metal foil 14 of the carrier metal foil 10, the metal laminate 20 shown in FIG1(ii) is obtained. Here, as shown in FIG1(ii), when there is a fracture portion B in the metal foil 14, the portion around the fracture portion B of the metal foil 14 may be embedded in the resin layer 16. Then, in the printed circuit board manufacturing step after the metal laminate is fabricated, the carrier 12 is peeled off from the metal laminate 20, and the metal foil 14 is patterned, including an etching step. However, since the portion around the fracture portion B of the metal foil 14 is embedded in the resin layer 16, when the metal foil 14 is etched, a portion of the resin layer 16 exposed beyond the fracture portion B of the metal foil 14 functions as a resist against etching. As a result, it is more difficult to remove the portion around the fracture portion B in the metal foil 14 by etching, resulting in residual metal.

[0012] The above-mentioned problems are effectively solved by the carrier-supported metal foil of the present invention. That is, by making the tensile strength of the carrier as high as 50.0 kgf / mm² or more, the metal foil can be firmly supported to ensure stability during operation. At the same time, by making the tensile strength of the metal foil as high as 50.0 kgf / mm² or more, the durability against loads directly applied to the metal foil can be improved when operating the carrier-supported metal foil. As described above, in the present invention, by controlling the tensile strength of both the carrier and the metal foil to a high value, rather than controlling the tensile strength of either one, the breakage and cracking of the metal foil can be suppressed very effectively.

[0013] Therefore, the tensile strength of the carrier is 50.0 kgf / mm² or more, preferably 50.0 kgf / mm² or more and 100.0 kgf / mm² or less, more preferably 50.0 kgf / mm² or more and 80.0 kgf / mm² or less, further preferably 55.0 kgf / mm² or more and 70.0 kgf / mm² or less, and particularly preferably 55.0 kgf / mm² or more and 65.0 kgf / mm² or less. The tensile strength values ​​in this specification refer to values ​​measured according to IPC-TM-650 2.4.18.

[0014] Furthermore, the tensile strength of the metal foil is 50.0 kgf / mm² or higher, preferably 50.0 kgf / mm² or higher and 100.0 kgf / mm² or lower, more preferably 55.0 kgf / mm² or higher and 80.0 kgf / mm² or lower, further preferably 60.0 kgf / mm² or higher and 70.0 kgf / mm² or lower, and particularly preferably 60.0 kgf / mm² or higher and 65.0 kgf / mm² or lower. Moreover, when the metal foil is used alone, it is difficult to measure its tensile strength due to its thinness. In such cases, the tensile strength of the metal foil can be calculated more effectively according to the procedure shown in the embodiments described later.

[0015] The ratio of the tensile strength TS2 of the metal foil to the tensile strength TS1 of the carrier (=TS2 / TS1) is preferably 0.70 to 1.40 and more preferably 0.80 to 1.30 and further preferably 0.90 to 1.20 and particularly preferably 0.95 to 1.15. By controlling the tensile strength of both the carrier and the metal foil within this range, the occurrence of breakage and cracking of the metal foil can be further effectively suppressed.

[0016] From the viewpoint of further effectively suppressing the breakage and cracking of metal foil during the printed circuit board manufacturing process, the carrier metal foil preferably maintains a certain tensile strength after heat treatment. Therefore, the tensile strength (post-heat peel strength) of the carrier after heating the carrier metal foil at 250°C for 60 minutes is preferably 45.0 kgf / mm² or more, more preferably 45.0 kgf / mm² or more and 95.0 kgf / mm² or less, further preferably 45.0 kgf / mm² or more and 75.0 kgf / mm² or less, particularly preferably 50.0 kgf / mm² or more and 65.0 kgf / mm² or less, and most preferably 50.0 kgf / mm² or more and 60.0 kgf / mm² or less. Furthermore, the tensile strength (peel strength after heating) of the metal foil after heating the substrate metal foil at 250°C for 60 minutes is preferably 45.0 kgf / mm² or more, more preferably 45.0 kgf / mm² or more and 95.0 kgf / mm² or less, further preferably 50.0 kgf / mm² or more and 75.0 kgf / mm² or less, particularly preferably 55.0 kgf / mm² or more and 65.0 kgf / mm² or less, and most preferably 55.0 kgf / mm² or more and 60.0 kgf / mm² or less.

[0017] The carrier system is a support used to support the metal foil to improve its operability. A typical carrier includes a metal layer. Examples of such carriers include aluminum foil, copper foil, stainless steel (SUS) foil, resin films coated with metals such as copper, or glass, with copper foil being preferred. The copper foil can be either rolled copper foil or electrolytic copper foil, with electrolytic copper foil being preferred. The thickness of the carrier is typically 250 μm or less, more typically 200 μm or less, and from the perspective of reducing CO2 emissions during manufacturing, it is preferably 6 μm or more and 18 μm or less, more preferably 7 μm or more and 16 μm or less, further preferably 8 μm or more and 14 μm or less, and particularly preferably 8 μm or more and 12 μm or less. A preferred method for measuring the thickness of the carrier is shown in the examples described later.

[0018] The metal foil is preferably copper foil or copper alloy foil, more preferably copper foil. The metal foil can be either electrolytic foil or rolled foil, preferably electrolytic foil (especially electrolytic copper foil). The thickness of the metal foil is typically 18 μm or less, but from the viewpoint of improving the fineness of circuit lines or laser processing, it is preferably 0.1 μm to 6 μm or less, more preferably 0.1 μm to 4 μm or less, further preferably 0.3 μm to 3 μm or less, and especially preferably 0.5 μm to 2.5 μm or less. Furthermore, in this specification, copper foil with a thickness within the above range is sometimes referred to as ultra-thin copper foil. When the carrier metal foil is between the release layer and the metal foil, or when the metal foil contains an auxiliary layer (e.g., a roughening layer, rust-preventing layer, silane coupling agent layer, auxiliary metal layer, etc., described later), the thickness of the auxiliary layer is included in the thickness of the metal foil. A preferred method for measuring the thickness of metal foil is shown in the examples described below.

[0019] Depending on the requirements, a roughening treatment can also be applied to the surface of the metal foil to form a roughened layer. Because the metal foil has a roughened layer, the adhesion between the metal laminate or printed circuit board and the resin layer can be improved. The roughened layer is formed of a plurality of roughened particles (bulbs), which preferably each contain metal particles, and more preferably copper particles. The copper particles may contain metallic copper or copper alloys. The roughening treatment for forming the roughened surface can preferably be performed by forming roughened particles from metal or alloy on the metal foil. For example, it is preferred to perform the roughening treatment according to a plating operation involving at least two plating steps, including: a sintering step, which precipitates and adheres fine metal particles to the metal foil; and a cover plating step, which is used to prevent the fine metal particles from falling off.

[0020] Depending on the requirements, a rust-preventive treatment can also be applied to the surface of the metal foil to form a rust-preventive layer. The rust-preventive treatment preferably includes a zinc plating process. The zinc plating process can be either zinc plating or zinc alloy plating, with zinc-nickel alloy plating being particularly preferred. The zinc-nickel alloy plating only needs to 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, by mass ratio, is preferably 1.2 to 10, more preferably 2 to 7, and even more preferably 2.7 to 4. Furthermore, the rust-preventive treatment preferably further includes a chromate treatment, which is more preferably performed on the zinc-plated surface after the zinc plating process. This further improves rust resistance. The rust-preventive treatment is particularly preferably a combination of zinc-nickel alloy plating and subsequent chromate treatment.

[0021] Depending on the requirements, a silane coupling agent can also be applied to the surface of the metal foil to form a silane coupling agent layer. This improves moisture resistance, chemical resistance, and adhesion to adhesives, etc. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, coating it, and then drying it. Examples of silane coupling agents include epoxy-functionalized silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane; or 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyl... Amino-functional silane coupling agents such as trimethoxysilane; or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane; or olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane; or acrylic acid-functional silane coupling agents such as 3-methacryloxypropyltrimethoxysilane; or imidazole-functional silane coupling agents such as imidazole silane; or tris(2-)-functional silane coupling agents such as tris(2-)-silane, etc.

[0022] Therefore, the carrier metal foil preferably has at least one layer selected from the group consisting of a roughening layer containing a plurality of roughening particles, a rust-preventing treatment layer, and a silane coupling agent layer. For example, when the carrier metal foil further has a roughening layer, a rust-preventing treatment layer, and a silane coupling agent layer, the order in which these layers are formed is not particularly limited, but it is preferred that the roughening layer, the rust-preventing treatment layer, and the silane coupling agent layer are sequentially deposited on the metal foil.

[0023] The carrier metal foil has a release layer on the carrier. The release layer has the following functions: weakening the release strength of the carrier, ensuring the stability of this strength, and thus suppressing the interdiffusion that may occur between the carrier and the metal foil during high-temperature pressing. Generally, the release layer is formed on one side of the carrier, or it may be formed on both sides. The release layer can be either an organic release layer or an inorganic release layer. Examples of organic components used for organic release layers include: nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids, etc. Examples of nitrogen-containing organic compounds include: triazole compounds, imidazole compounds, etc., among which triazole compounds are preferred from the viewpoint that they are easy to stabilize in terms of 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, etc. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, trithiocyanate, and 2-benzimidazole thiol. Examples of carboxylic acids include monocarboxylic acids and dicarboxylic acids. On the other hand, examples of inorganic components used in inorganic release layers include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and chromate-treated films. The thickness of the release layer is typically 1 nm to 1 μm, preferably 5 nm to 500 nm.

[0024] Other functional layers may also be provided between the release layer and the carrier and / or the metal foil. Examples of such other functional layers include an auxiliary metal layer. The auxiliary metal layer preferably contains nickel and / or cobalt. By forming such an auxiliary metal layer on one side of the carrier surface and / or one side of the metal foil surface, interdiffusion that may occur between the carrier and the metal foil during high-temperature or long-term hot pressing can be further suppressed, thus ensuring the stability of the carrier's peel strength. The thickness of the auxiliary metal layer is preferably 0.001 μm to 3 μm.

[0025] Method for manufacturing carrier-attached metal foil The carrier-attached metal foil of the present invention can be manufactured by the following method: (1) preparing a carrier; (2) forming a release layer on the carrier; and (3) forming a metal foil on the release layer. Hereinafter, an example of a preferred method for manufacturing the carrier-attached metal foil of the present invention will be described.

[0026] (1) Preparation of the carrier First, a carrier for use as a support is prepared. A typical carrier includes a metal layer. Examples of such carriers, as mentioned above, include: aluminum foil, copper foil, stainless steel (SUS) foil, resin film coated with a metal such as copper, or glass, with copper foil being preferred. The copper foil can be either rolled copper foil or electrolytic copper foil, with electrolytic copper foil being preferred.

[0027] When using electrolytic copper foil as a carrier, it is preferable to set the conditions for electrolytic foil making as follows. That is, a sulfuric acid-based copper electrolyte is used, with the copper concentration adjusted to 60 g / L to 85 g / L (preferably 50 g / L to 70 g / L), the sulfuric acid concentration adjusted to 100 g / L to 250 g / L (preferably 200 g / L to 250 g / L), the chlorine concentration adjusted to 1 mg / L to 3 mg / L (preferably 1 mg / L to 2 mg / L), and the gelatin concentration as an additive adjusted to 0.3 mg / L to 5 mg / L (preferably 1 mg / L to 3 mg / L). A DSA (Dimensionally Stable Anode) is used as the anode, and the electrolyte temperature is 40°C to 60°C (preferably 50°C to 60°C), and the current density is 30 A / dm² to 75 A / dm² (preferably 40 A / dm² to 60 A / dm²). Electrolysis is performed under conditions below 2°C, thereby obtaining electrolytic copper foil with the desired tensile strength. Potassium iodide (iodine concentration 1 mg / L to 10 mg / L) or polyethyleneimine with a molecular weight of 3000 or higher (concentration 30 mg / L to 200 mg / L) can be used instead of gelatin as additives. Thus, by adding gelatin or similar additives to the electrolyte and controlling the electrolysis conditions within the aforementioned range, it is easier to form a carrier with high tensile strength. Furthermore, when the copper foil with the carrier is heat-treated, the decrease in the tensile strength of the carrier can be suppressed.

[0028] (2) Formation of a release layer on a carrier. The release layer can be either an organic release layer or an inorganic release layer. Preferred examples of organic and inorganic release layers are as described above. The formation of the release layer can be carried out by contacting at least one surface of the carrier with a solution containing the release layer component, thereby fixing the release layer component to the surface of the carrier. When the carrier is in contact with the solution containing the release layer component, the contact can be carried out by immersing the carrier in the solution containing the release layer component, spraying the solution containing the release layer component onto the carrier, or allowing the solution containing the release layer component to flow onto the carrier. Alternatively, a method can be used to form a coating of the release layer component using a vapor phase method such as vapor deposition or sputtering. Furthermore, fixing the release layer component to the surface of the carrier can be carried out by adsorbing the solution containing the release layer component onto the surface of the carrier or drying the surface of the carrier, or electrodepositing the release layer component in the solution containing the release layer component onto the surface of the carrier.

[0029] (3) The metal foil is formed on the release layer. For example, the metal foil can be formed by wet film formation methods such as electroless metal plating and electrolytic metal plating, dry film formation methods such as sputtering and chemical vapor deposition, or combinations thereof. It is preferable to form an extremely thin copper foil by electrolytic copper plating. In particular, from the viewpoint of improving the tensile strength of the extremely thin copper foil, it is preferable to set the conditions for electrolytic foil forming of the extremely thin copper foil as follows. That is, by using a sulfuric acid-based copper electrolyte with a copper concentration adjusted to 40 g / L to 80 g / L (more preferably 50 g / L to 70 g / L), a sulfuric acid concentration adjusted to 180 g / L to 260 g / L (more preferably 200 g / L to 250 g / L), and a carboxybenzotriazole (CBTA) concentration adjusted to more than 0 ppm and less than 200 ppm, and using a DSA (dimension stability anode) as the anode, and performing electrolysis under conditions of a liquid temperature of 35°C to 60°C (more preferably 40°C to 55°C) and a current density of 3 A / dm² to 80 A / dm² (more preferably 5 A / dm² to 80 A / dm², and even more preferably 6 A / dm² to 75 A / dm²), the desired electrolytic copper foil can be obtained better. The concentration of CBTA in the electrolyte is preferably 0.1 ppm to 100 ppm, 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. Thus, by adding carboxybenzotriazole (CBTA) as an additive to the electrolyte and controlling the electrolysis conditions within the above range, it is easy to form a metal foil with high tensile strength. Furthermore, when the copper foil on the substrate is heat-treated, the decrease in the tensile strength of the metal foil can be suppressed.

[0030] As required, the surface of the metal foil may also be subjected to roughening treatment, rust prevention treatment, and / or silane coupling agent treatment to form a roughening layer, rust prevention treatment layer, and / or silane coupling agent layer containing a plurality of roughening particles. These treatments are as described above.

[0031] Metal Lamination Laminate The carrier metal foil of the present invention is preferably used for manufacturing a metal lamination laminate for printed circuit boards. That is, according to a preferred embodiment of the present invention, a metal lamination laminate (more preferably a copper lamination laminate) having the above-mentioned carrier metal foil is provided. The metal lamination laminate comprises: a carrier metal foil, which sequentially comprises a carrier, a release layer, and a metal foil; and a resin layer disposed on the surface of the metal foil of the carrier metal foil (the side of the metal foil opposite to the release layer). The above-mentioned preferred embodiment of the carrier metal foil is also directly applicable to the carrier metal foil of the metal lamination laminate. The carrier metal foil may be disposed on one side of the resin layer or on both sides. The resin layer is composed of resin, preferably composed of insulating resin. The resin layer is preferably a prepreg and / or resin sheet. The term prepreg refers to a general term for composite materials made by impregnating a substrate such as a synthetic resin board, glass board, glass fabric, glass non-woven fabric, or paper with synthetic resin. Preferred examples of insulating resins include epoxy resin, cyanate ester resin, bismaleimide triterpenoid resin (BT resin), polyphenylene ether resin, and phenolic resin. Examples of insulating resins constituting resin sheets include epoxy resin, polyimide resin, and polyester resin. Furthermore, from the viewpoint of improving insulation, the resin layer may also contain filler particles including various inorganic particles such as silicon dioxide and alumina. 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 consist of multiple layers. The prepreg and / or resin sheet may also be disposed on the carrier metal foil through a primer resin layer pre-coated to the surface of the metal foil.

[0032] Printed Circuit Board The carrier metal foil of the present invention is preferably used for manufacturing a printed circuit board. That is, according to a preferred embodiment of the present invention, a printed circuit board having the aforementioned carrier metal foil, or a method thereof, is provided. The printed circuit board of this embodiment is composed of layers comprising a resin layer and a metal layer sequentially laminated. Furthermore, regarding the resin layer, the metal laminate is as described above. In any case, the printed circuit board can be constructed using known layers. Specific examples of the printed circuit board include: a single-sided or double-sided printed circuit board in which the metal foil of the present invention is bonded to one or both sides of a prepreg and hardened to form a laminate and then a circuit is formed; or a multilayer printed circuit board formed by multiplying such printed circuit boards. Other specific examples include: a flexible printed circuit board in which the metal foil of the present invention is formed on a resin film to form a circuit; COF (Chip On Film); TAB (Tape Automated Bonding); etc. Furthermore, as other specific examples, examples include: coating the metal foil of the present invention with the aforementioned resin layer to form a resin-attached metal foil; depositing the resin layer as an insulating adhesive layer on the aforementioned printed circuit board; and then using the metal foil as all or part of the wiring layer to form a build-up circuit board by a modified semi-additive process (MSAP), subtractive process, or other operations; or removing the metal foil and forming a build-up circuit board by a semi-additive process (SAP); or directly building up on a wafer by alternately and repeatedly depositing the resin-attached metal foil and forming the circuit on a semiconductor integrated circuit. The carrier metal foil of the present invention can also be well used in manufacturing methods using a coreless build-up method, which does not use a so-called core substrate but alternately deposits insulating resin layers and conductor layers. [Examples]

[0033] The present invention will be further described in detail by way of the following examples.

[0034] Examples 1 to 11 are prepared and evaluated as follows.

[0035] (1) Preparation of the carrier In Examples 1 to 6 and 11, a copper electrolyte with the following composition, a cathode, and a DSA (dimension stability anode) as the anode were used. Electrolysis was carried out at a solution temperature of 50°C and a current density of 60 A / dm² to obtain an electrolytic copper foil of a specific thickness as a carrier. <Composition of copper electrolyte> - Copper concentration: 80 g / L - Sulfuric acid concentration: 250 g / L - Chlorine concentration: 1.5 mg / L - Gelatin concentration: 2 mg / L

[0036] On the other hand, in Examples 7-10, a copper electrolyte with the composition shown below, a cathode, and a DSA (dimension stability anode) as the anode were used for electrolysis at a solution temperature of 50°C and a current density of 70 A / dm² to obtain an electrolytic copper foil of a specific thickness as a carrier. <Composition of the copper electrolyte> - Copper concentration: 80 g / L - Sulfuric acid concentration: 300 g / L - Chlorine concentration: 30 mg / L - Gelatin concentration: 5 mg / L

[0037] (2) Formation of the release layer: The electrode surface of the acid-washed carrier is immersed in an aqueous solution of CBTA containing 1 g / L carboxybenzotriazole (CBTA), 150 g / L sulfuric acid, and 10 g / L copper for 30 seconds at a liquid temperature of 30°C, so that the CBTA component is adsorbed onto the electrode surface of the carrier. In this way, a CBTA layer is formed on the electrode surface of the carrier as an organic release layer.

[0038] (3) Formation of the auxiliary metal layer: The carrier with the organic release layer is immersed in a solution containing 20 g / L nickel prepared using nickel sulfate. Under the conditions of liquid temperature 45°C, pH value 3, and current density 5 A / dm², nickel equivalent to an adhesion amount of 0.001 μm in thickness is attached to the organic release layer. In this way, a nickel layer is formed on the organic release layer as an auxiliary metal layer.

[0039] (4) Formation of ultra-thin copper foil: A carrier with an auxiliary metal layer is immersed in a copper solution with the composition shown below, and electrolysis is performed at a solution temperature of 50°C and a current density of 5 A / dm² to 40 A / dm² (Examples 1-10) or 70 A / dm² (Example 11) to form an ultra-thin copper foil of a specific thickness on the auxiliary metal layer. <Composition of solution> - Copper concentration: 60 g / L - Sulfuric acid concentration: 200 g / L - CBTA concentration: 5.0 ppm (Examples 1, 4-8 and 11) or 0 ppm (Examples 2, 3, 9 and 10)

[0040] (5) Roughening treatment: A roughened copper foil is formed by applying a roughening treatment to the surface of the extremely thin copper foil thus formed, thereby obtaining a carrier copper foil. The roughening treatment includes: a plating step, which precipitates and attaches fine copper particles on the extremely thin copper foil; and a cover plating step, which is used to prevent the fine copper particles from falling off. In the plating step, 9-phenylacridine (9PA) and chlorine are added to an acidic copper sulfate solution containing a copper concentration of 10 g / L and a sulfuric acid concentration of 200 g / L at a liquid temperature of 25°C, respectively, to achieve a 9PA concentration of 60 ppm and a chlorine concentration of 50 ppm, and the roughening treatment is performed under a current density of 20 A / dm 2. In the subsequent cover plating step, an acidic copper sulfate solution containing a copper concentration of 70 g / L and a sulfuric acid concentration of 240 g / L is used, and electrodeposition is performed under smooth plating conditions at a liquid temperature of 52°C and a current density of 15 A / dm 2.

[0041] (6) Rust prevention treatment The roughened surface of the obtained carrier copper foil is subjected to rust prevention treatment including zinc-nickel alloy plating and chromate treatment. First, zinc-nickel alloy plating is applied to the surface of the roughened layer and the carrier using a solution containing 1 g / L zinc, 2 g / L nickel and 80 g / L potassium pyrophosphate at a liquid temperature of 40°C and a current density of 0.5 A / dm². Next, chromate treatment is applied to the zinc-nickel alloy plating surface using an aqueous solution containing 1 g / L chromic acid at a pH of 12 and a current density of 1 A / dm².

[0042] (7) The silane coupling agent treatment is performed by adsorbing an aqueous solution containing a commercially available silane coupling agent onto the surface of the roughened copper foil with the carrier copper foil, and evaporating the water using an electric heater. At this time, the carrier side is not treated with the silane coupling agent.

[0043] (8) In heat treatment examples 3 and 10, the carrier copper foil treated with silane coupling agent was heat-treated at 175°C for 5 minutes. On the other hand, in examples 1, 2 and 4 to 9, this heat treatment was not performed.

[0044] (9) Evaluation The copper foil with the substrate thus obtained shall be evaluated for various properties as follows.

[0045] (9a) Thickness The thickness of the carrier and the ultrathin copper foil with the carrier was measured as follows. First, the carrier copper foil was cut into 100 mm squares and its weight WA was measured by an electronic balance. Next, the carrier was peeled off from the carrier copper foil and its weight WB was measured by an electronic balance. Then, the thickness of the carrier was calculated based on the weight WB and the specific gravity of copper, and the thickness of the ultrathin copper foil was calculated based on the difference between the weight WA and the weight WB (=WA-WB) and the specific gravity of copper. The results are shown in Table 1.

[0046] (9b) The tensile strength of the carrier and the ultrathin copper foil under normal conditions was determined as follows. First, the tensile strength TS 3 (kgf / mm 2) of the copper foil with the carrier was determined according to IPC-TM650 2.4.18. Next, the carrier was peeled off from the copper foil with the carrier, and the tensile strength TS 1 (kgf / mm 2) of the carrier was determined according to IPC-TM650 2.4.18. Since the ultrathin copper foil is difficult to measure the tensile strength using the same procedure due to its thinness, it was calculated as follows. The values ​​obtained by multiplying TS 3 (kgf / mm 2) and TS 1 (kgf / mm 2) by the cross-sectional area of ​​each specimen were set as TS 3' (kgf) and TS 1' (kgf), respectively. The cross-sectional area of ​​the ultrathin copper foil specimen was set as A (mm 2), and the value calculated according to the formula (TS 3' - TS 1') / A was taken as the tensile strength of the ultrathin copper foil. The results are shown in Table 1.

[0047] (9c) Tensile strength after heating: Before measuring the tensile strength, the copper foil with the carrier was heated in an oven at 250°C for 60 minutes in an atmospheric atmosphere, and then cooled to room temperature. Otherwise, the tensile strength of the carrier and the ultrathin copper foil after heating was measured in the same order as the tensile strength under normal conditions. Furthermore, in Examples 2, 3, 9 and 10, only the tensile strength of the carrier after heating was measured, and the tensile strength of the ultrathin copper foil after heating was not calculated. Also, in Example 11, the tensile strength of the carrier and the ultrathin copper foil after heating was not measured. The results are shown in Table 1.

[0048] (9d) Crack Count Measurement As an indicator of the crack resistance of ultrathin copper foil, the crack count is measured as follows. First, as shown in Figure 2, the carrier copper foil is cut into 150 mm squares. Next, one side of the cut carrier copper foil 30 is fixed with a width of 25 mm. Then, holding the side opposite to the fixed side, the carrier copper foil 30 is twisted twice on each side. This twisting is performed as shown in Figures 3(i) to (iii) until the carrier copper foil 30 changes from a horizontal state to an angle of 45° relative to the horizontal plane. After releasing the fixation, the carrier copper foil 30 is rotated 90°, and the above twisting step is performed again. In this way, the twisting step is applied to all four sides of the carrier copper foil 30. Subsequently, as shown in Figure 2, for the central portion of the cut-out carrier copper foil 30, i.e., a test area of ​​100 mm × 100 mm (=1 dm 2), the number of cracks on one side of the ultrathin copper foil was counted using an optical microscope. Each example underwent the above operation three times, and the average value was taken as the number of cracks. The results are shown in Table 1.

[0049] [Table 1] Table 1 Thickness (μm) Tensile strength (kgf / mm) 2 ) evaluate carrier ultra-thin copper foil carrier ultra-thin copper foil Number of cracks (pieces / dm) 2 ) normal After heating (250℃ x 60 minutes) normal After heating (250℃ x 60 minutes) Example 1 11.0 2.2 52.5 50.7 60.5 54.0 9.3 Example 2* 11.0 2.2 52.5 50.7 39.0 Not implemented 55.6 Example 3* 11.0 2.2 52.5 50.7 30.2 unrealized 19.0 Example 4 11.0 2.7 55.1 50.5 58.6 52.3 9.0 Example 5 8.9 2.2 55.9 53.1 61.1 54.6 18.9 Example 6 8.9 2.7 56.9 53.2 50.4 45.0 14.0 Example 7* 11.0 2.2 39.7 34.1 50.4 45.0 55.7 Example 8* 11.0 2.7 39.3 33.8 50.6 45.2 40.9 Example 9* 11.0 2.2 40.1 34.5 39.0 unrealized 73.8 Example 10* 11.0 2.2 39.0 33.5 29.8 Not implemented 36.5 Example 11 11.0 2.2 55.4 Not implemented 63.8 Not implemented 6.8 * indicates a comparative example. [Simplified Explanation of the Diagram]

[0009] Figures 1(i) and (ii) are flowcharts illustrating the steps of fabricating a metal laminate using a carrier metal foil. These figures are used to explain the mechanism by which residual metal is generated due to fractures in the metal foil. Figure 2 is a top view of the cut carrier copper foil used for determining the number of cracks in the embodiment, showing the fixed area and the test area. Figures 3(i) to (iii) are flowcharts illustrating the steps of applying a torsion treatment to the carrier copper foil of Figure 2.

Claims

1. A carrier-supported metal foil comprising, in sequence, a carrier, a release layer, and a metal foil, wherein the tensile strength of the carrier is 50.0 kgf / mm² or more, and the tensile strength of the metal foil is 50.0 kgf / mm² or more.

2. The carrier metal foil of claim 1, after being heated at 250°C for 60 minutes, has a tensile strength of 45.0 kgf / mm2 or more, and / or the tensile strength of the metal foil is 45.0 kgf / mm2 or more.

3. The carrier metal foil as claimed in claim 1 or 2, wherein both the carrier and the metal foil are copper foil.

4. The carrier metal foil as requested in claim 1 or 2, wherein the thickness of the carrier is more than 6 μm and less than 18 μm.

5. The carrier metal foil as claimed in claim 1 or 2, wherein the thickness of the metal foil is more than 0.1 μm and less than 6 μm.

6. The carrier metal foil of claim 1 or 2, wherein the metal foil further comprises at least one layer selected from the group consisting of a roughening layer comprising a plurality of roughening particles, a rust-preventing treatment layer, and a silane coupling agent layer.

7. The carrier metal foil of claim 1 or 2, wherein an auxiliary metal layer is further provided between the release layer and the carrier and / or the metal foil.

8. The carrier metal foil as claimed in claim 1 or 2, wherein the ratio of the tensile strength of the metal foil to the tensile strength of the carrier is 0.70 or more and 1.40 or less.

9. A metal laminate having a carrier metal foil as claimed in claim 1 or 2.

10. A printed circuit board having a carrier metal foil as claimed in claim 1 or 2.

11. A method for manufacturing a printed circuit board, characterized in that the printed circuit board is manufactured using a carrier metal foil as claimed in claim 1 or 2.

Images