WO2023189565A1

WO2023189565A1 - Carrier-attached metal foil, metal-clad laminate, and printed wiring board

Info

Publication number: WO2023189565A1
Application number: PCT/JP2023/009939
Authority: WO
Inventors: 佑太佐々木; 哲聡 ▲高▼梨; 和広吉川
Original assignee: 三井金属鉱業株式会社
Priority date: 2022-03-29
Filing date: 2023-03-14
Publication date: 2023-10-05
Also published as: TW202346098A

Abstract

Provided is a carrier-attached metal foil in which the occurrence of fractures or cracks in the metal foil during handling thereof can be suppressed. The carrier-attached metal foil comprises a carrier, a release layer, and a metal foil in this order, wherein the tensile strength of the carrier is not less than 50.0 kgf/mm² and the tensile strength of the metal foil is not less than 50.0 kgf/mm².

Description

Metal foil with carrier, metal clad laminate and printed wiring board

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

Metal foil with a carrier is widely used as a material for manufacturing printed wiring boards. Metal foil with a carrier typically has a structure comprising a carrier, a release layer, and a metal foil (for example, ultra-thin copper foil) in this order, and is made of an insulating resin such as a glass-epoxy base material, a phenol base material, or a polyimide base material. It is bonded to a base material (resin layer) by hot pressing to form a metal-clad laminate (for example, a copper-clad laminate), and is used in the manufacture of printed wiring boards.

When a metal foil with a carrier is hot pressed at high temperatures (for example, 250°C or higher), the peel strength between the carrier and the metal foil increases, and there is a problem that it becomes difficult to peel off the carrier from the metal foil. be. Metal foils with carriers that deal with such problems are known, and for example, in Patent Document 1 (International Publication No. 2015/080052), a metal foil with a carrier of 40 kgf/mm ² is used as a carrier after heat treatment at 250° C. for 60 minutes. A carrier-attached copper foil characterized by using an electrolytic copper foil having the above tensile strength is disclosed. According to such a copper foil with a carrier, formation of a connecting portion in the bonding interface layer between the carrier and the copper foil is suppressed, and the carrier can be easily peeled off from the copper foil.

International Publication No. 2015/080052

By the way, due to recent efforts towards SDGs (Sustainable Development Goals) and promotion of carbon neutrality, it is expected that carriers in metal foils with carriers will become thinner for the purpose of reducing _CO2 during manufacturing. In this regard, there is a concern that as the carrier becomes thinner, the risk of breakage or cracking of the metal foil when handling the metal foil with the carrier increases. In particular, breakage or cracking of the metal foil during handling may lead to defects due to residual metal in the printed wiring board manufacturing process, and improvements are required.

The present inventors have recently developed a metal foil with a carrier that has a tensile strength of the carrier of 50.0 kgf/mm ² or more and a tensile strength of the metal foil of 50.0 kgf/mm ² or more. It was found that the occurrence of breakage or cracks in metal foil can be suppressed.

Therefore, an object of the present invention is to provide a metal foil with a carrier that can suppress the occurrence of breakage or cracking of the metal foil during handling.

According to the present invention, the following aspects are provided.
[Aspect 1]
A carrier-attached metal foil comprising a carrier, a release layer, and a metal foil in this order,
A metal foil with a carrier, wherein the carrier has a tensile strength of 50.0 kgf/mm ² or more, and the metal foil has a tensile strength of 50.0 kgf/mm ² or more.
[Aspect 2]
According to aspect 1, the carrier has a tensile strength of 45.0 kgf/mm ² or more and/or the metal foil has a tensile strength of 45.0 kgf/mm ² or more after heating at 250° C. for 60 minutes. metal foil with carrier.
[Aspect 3]
The metal foil with a carrier according to aspect 1 or 2, wherein both the carrier and the metal foil are copper foils.
[Aspect 4]
The metal foil with a carrier according to any one of aspects 1 to 3, wherein the carrier has a thickness of 6 μm or more and 18 μm or less.
[Aspect 5]
The metal foil with a carrier according to any one of aspects 1 to 4, wherein the metal foil has a thickness of 0.1 μm or more and 6 μm or less.
[Aspect 6]
Embodiments 1 to 1, further comprising, on the metal foil, at least one layer selected from the group consisting of a roughening layer composed of a plurality of roughening particles, a rust prevention treatment layer, and a silane coupling agent layer. 5. The carrier-attached metal foil according to any one of 5.
[Aspect 7]
The carrier-attached metal foil according to any one of aspects 1 to 6, further comprising an auxiliary metal layer between the release layer and the carrier and/or the metal foil.
[Aspect 8]
A metal-clad laminate comprising the carrier-attached metal foil according to any one of aspects 1 to 7.
[Aspect 9]
A printed wiring board comprising the carrier-attached metal foil according to any one of aspects 1 to 7.
[Aspect 10]
A method for manufacturing a printed wiring board, comprising manufacturing a printed wiring board using the carrier-attached metal foil according to any one of aspects 1 to 7.

It is a process flowchart for producing a metal-clad laminate using a metal foil with a carrier, and is a diagram for explaining a mechanism in which residual metal is generated by a fractured portion formed in the metal foil. It is a top view of the cut out copper foil with a carrier used for the crack number measurement in an example, and shows a fixed area and a test area. It is a flowchart of the twist|twisting process performed to the copper foil with a carrier of FIG.

Metal foil with carrier The metal foil with carrier according to the present invention includes a carrier, a release layer, and a metal foil in this order. In this metal foil with a carrier, the carrier has a tensile strength of 50.0 kgf/mm ² or more, and the metal foil has a tensile strength of 50.0 kgf/mm ² or more. In this way, in the metal foil with a carrier, by setting the tensile strength of the carrier to 50.0 kgf/mm ² or more and also setting the tensile strength of the metal foil to 50.0 kgf/mm ² or more, the metal foil can be It is possible to suppress the occurrence of breakage or cracks.

As mentioned above, breakage or cracking of the metal foil during handling of the metal foil with a carrier may lead to defects due to residual metal in the printed wiring board manufacturing process. Here, the mechanism by which residual metal is generated due to breakage of metal foil, etc. will be explained with reference to FIG. 1. As shown in FIG. 1(i), when the carrier-attached metal foil 10 including the carrier 12, a release layer (not shown), and the metal foil 14 is handled, the metal foil 14 is broken and a broken part B is formed. It can happen that it is formed. A metal-clad laminate 20 shown in FIG. 1(ii) is obtained by laminating a resin layer 16 (for example, prepreg) on the surface of the carrier-attached metal foil 10 on the metal foil 14 side and hot pressing. Here, as shown in FIG. 1(ii), if the metal foil 14 has a broken portion B, the peripheral portion of the broken portion B of the metal foil 14 may be buried in the resin layer 16. In the printed wiring board manufacturing process after manufacturing the metal-clad laminate, the carrier 12 is peeled off from the metal-clad laminate 20, and the metal foil 14 is subjected to patterning including an etching process. However, since the peripheral part of the broken part B of the metal foil 14 is buried in the resin layer 16, when etching the metal foil 14, the part surrounding the broken part B of the metal foil 14 is exposed to the surface. A portion of the resin layer 16 ends up functioning as a resist for etching. As a result, it becomes difficult to remove the peripheral portion of the fractured portion B in the metal foil 14 by etching, and residual metal is generated.

Such problems are effectively solved by the carrier-attached metal foil of the present invention. In other words, by increasing the tensile strength of the carrier to 50.0 kgf/mm ² or more, it is possible to firmly support the metal foil and ensure stability during handling, and also to increase the tensile strength of the metal foil to 50.0 kgf/mm 2 or more. By setting it as high as /mm ² or more, it is possible to improve the durability against direct loads on the metal foil when handling the metal foil with a carrier. In this way, in the present invention, rather than controlling the tensile strength of either the carrier or the metal foil, the tensile strength of both is controlled to a high value, thereby extremely effectively preventing metal foil from breaking and cracking. can suppress the occurrence of

Therefore, the tensile strength of the carrier is 50.0 kgf/mm ² or more, preferably 50.0 kgf/mm ² or more and 100.0 kgf/mm ² or less, more preferably 50.0 kgf/mm ² or more and 80.0 kgf/mm ² Below, it is more preferably 55.0 kgf/mm ² or more and 70.0 kgf/mm ² or less, particularly preferably 55.0 kgf/mm ² or more and 65.0 kgf/mm ² or less. Each numerical value of tensile strength in this specification shall mean a value measured in accordance with IPC-TM-650 2.4.18.

Further, the tensile strength of the metal foil is 50.0 kgf/mm ² or more, preferably 50.0 kgf/mm ² or more and 100.0 kgf/mm ² or less, more preferably 55.0 kgf/mm ² or more and 80.0 kgf/mm 2 or more. ² or less, more preferably 60.0 kgf/mm ² or more and 70.0 kgf/mm ² or less, particularly preferably 60.0 kgf/mm ² or more and 65.0 kgf/mm ² or less. In addition, when it is difficult to measure the tensile strength of a single metal foil due to its thinness, the tensile strength of the metal foil can be preferably calculated by the procedure shown in the Examples described later.

The ratio of the tensile strength TS ₂ of the metal foil to the tensile strength TS ₁ of the carrier (=TS ₂ /TS ₁ ) is preferably 0.70 or more and 1.40 or less, more preferably 0.80 or more and 1.30 or less. , more preferably 0.90 or more and 1.20 or less, particularly preferably 0.95 or more and 1.15 or less. By controlling the tensile strength of both the carrier and the metal foil to fall within this range, it is possible to more effectively suppress the occurrence of breakage and cracks in the metal foil.

In order to more effectively suppress the occurrence of breaks and cracks in the metal foil during the printed wiring board manufacturing process, the carrier-attached metal foil is designed so that the carrier and/or the metal foil maintains a predetermined tensile strength even after heat treatment. It is preferable that Therefore, the tensile strength (peeling strength after heating) of the carrier after heating the carrier-attached metal foil at 250°C for 60 minutes is preferably 45.0 kgf/mm ² or more, more preferably 45.0 kgf/mm ² or more. 95.0 kgf/mm ² or less, more preferably 45.0 kgf/mm ² or more and 75.0 kgf/mm ² or less, particularly preferably 50.0 kgf/mm ² or more and 65.0 kgf/mm ² or less, most preferably 50.0 kgf/mm / ^mm2 or more and 60.0 kgf/ ^mm2 or less. Further, the tensile strength (peeling strength after heating) of the metal foil after heating the carrier-attached metal foil at 250°C for 60 minutes is preferably 45.0 kgf/mm ² or more, more preferably 45.0 kgf/mm ² 95.0 kgf/mm ² or more, more preferably 50.0 kgf/mm ² or more and 75.0 kgf/mm ² or less, particularly preferably 55.0 kgf/mm ² or more and 65.0 kgf/mm ² or less, most preferably 55.0 kgf/mm 2 or more and 65.0 kgf/mm 2 or less. 0 kgf/mm ² or more and 60.0 kgf/mm ² or less.

A carrier is a support for supporting a metal 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 whose surfaces are coated with metal such as copper, and glass, with copper foil being preferred. The copper foil may be either a rolled copper foil or an electrolytic copper foil, but preferably an electrolytic copper foil. The thickness of the carrier is typically 250 μm or less, more typically 200 μm or less, and from the viewpoint of reducing _CO2 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, and even more preferably The thickness is 8 μm or more and 14 μm or less, particularly preferably 8 μm or more and 12 μm or less. A preferred method for measuring the thickness of the carrier will be shown in the Examples described below.

The metal foil is preferably a copper foil or a copper alloy foil, and more preferably a copper foil. The metal foil may be either an electrolytic foil or a rolled foil, but is preferably an electrolytic foil (particularly preferably an electrolytic copper foil). The thickness of the metal foil is typically 18 μm or less, and from the viewpoint of thinning the circuit and improving laser processability, it is preferably 0.1 μm or more and 6 μm or less, more preferably 0.1 μm or more and 4 μm or less, and even more preferably The thickness is 0.3 μm or more and 3 μm or less, particularly preferably 0.5 μm or more and 2.5 μm or less. Note that in this specification, a copper foil having a thickness within the above range may be referred to as an ultra-thin copper foil. When the carrier-attached metal foil includes an auxiliary layer between the release layer and the metal foil or on the metal foil (for example, a roughening layer, a rust prevention treatment layer, a silane coupling agent layer, an auxiliary metal layer, etc. described below), The thickness of this auxiliary layer shall be included in the thickness of the metal foil. A preferred method for measuring the thickness of the metal foil will be shown in the Examples described below.

If desired, the surface of the metal foil may be subjected to a roughening treatment to form a roughened layer. By providing a roughened layer on the metal foil, it is possible to improve the adhesion with the resin layer during the production of metal-clad laminates or printed wiring boards. The roughening layer includes a plurality of roughening particles (bumps), and each of the plurality of roughening particles preferably consists of metal particles, and preferably copper particles. The copper particles may be made of metallic copper or may be made of a copper alloy. The roughening treatment for forming the roughened surface can be preferably performed by forming roughening particles of metal or alloy on the metal foil. For example, roughening treatment is performed according to a plating method that involves at least two types of plating processes, including a baking plating process in which fine metal particles are precipitated and adhered to the metal foil, and a cover plating process to prevent the fine metal particles from falling off. is preferably carried out.

If desired, the surface of the metal foil may be subjected to rust prevention treatment to form a rust prevention treatment layer. Preferably, the rust prevention treatment includes plating treatment using zinc. The plating treatment using zinc may be either a zinc plating treatment or a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment that contains at least Ni and Zn, and may further contain other elements such as Sn, Cr, and Co. The Ni/Zn adhesion ratio in zinc-nickel alloy plating is preferably 1.2 or more and 10 or less, more preferably 2 or more and 7 or less, and even more preferably 2.7 or more and 4 or less, in terms of mass ratio. Moreover, it is preferable that the rust prevention treatment further includes chromate treatment, and it is more preferable that this chromate treatment is performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust prevention properties can be further improved. A particularly preferred anticorrosion treatment is a combination of zinc-nickel alloy plating treatment followed by chromate treatment.

If desired, the surface of the metal foil may be treated with a silane coupling agent to form a silane coupling agent layer. This makes it possible to improve moisture resistance, chemical resistance, adhesion to adhesives, and the like. The silane coupling agent layer can be formed by appropriately diluting a silane coupling agent, applying it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltrimethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. Amino-functional silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane, or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacrylic Examples include acrylic-functional silane coupling agents such as roxypropyltrimethoxysilane, or imidazole-functional silane coupling agents such as imidazole silane, or triazine-functional silane coupling agents such as triazine silane.

Therefore, the carrier-attached metal foil further includes at least one layer selected from the group consisting of a roughening layer composed of a plurality of roughening particles, a rust prevention treatment layer, and a silane coupling agent layer on the metal foil. It is preferable to prepare. For example, when the metal foil with a carrier further includes a roughened layer, a rust prevention treatment layer, and a silane coupling agent layer, the order of construction of these layers is not particularly limited, but the roughened layer is formed on the metal foil. , the anticorrosive layer and the silane coupling agent layer are preferably laminated in this order.

The metal foil with a carrier has a release layer on the carrier. The peeling layer is a layer that has the function of weakening the peeling strength of the carrier, ensuring the stability of this strength, and further suppressing mutual diffusion that may occur between the carrier and metal foil during press molding at high temperatures. . Although the release layer is generally formed on one side of the carrier, 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, carboxylic acids, and the like. Examples of the nitrogen-containing organic compound include triazole compounds, imidazole compounds, etc. Among them, triazole compounds are preferred because they have easy releasability. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N',N'-bis(benzotriazolylmethyl)urea, 1H-1,2,4-triazole and 3-amino- Examples include 1H-1,2,4-triazole. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, 2-benzimidazolethiol, and the like. Examples of carboxylic acids include monocarboxylic acids, dicarboxylic acids, and the like. On the other hand, examples of inorganic components used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and a chromate-treated film. The thickness of the release layer is typically 1 nm or more and 1 μm or less, preferably 5 nm or more and 500 nm or less.

Other functional layers may be provided between the release layer and the carrier and/or metal foil. Examples of such other functional layers include auxiliary metal layers. Preferably, the auxiliary metal layer consists 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 metal foil, mutual diffusion that may occur between the carrier and the metal foil during hot press molding at high temperatures or for a long time can be further suppressed. , the stability of the peel strength of the carrier can be ensured. The thickness of the auxiliary metal layer is preferably 0.001 μm or more and 3 μm or less.

Method for manufacturing metal foil with carrier The metal foil with carrier of the present invention can be produced by (1) preparing a carrier, (2) forming a release layer on the carrier, and (3) forming a metal foil on the release layer. can be manufactured. Hereinafter, one example of a preferred method for manufacturing the carrier-attached metal foil according to the present invention will be described.

(1) Preparation of carrier First, prepare a carrier as a support. Typical carriers include metal layers. Examples of such carriers include, as described above, aluminum foil, copper foil, stainless steel (SUS) foil, resin films whose surfaces are coated with metal such as copper, and glass, with copper foil being preferred. The copper foil may be either a rolled copper foil or an electrolytic copper foil, but preferably an electrolytic copper foil.

When using electrolytic copper foil as a carrier, it is preferable that the conditions for electrolytically forming the foil are as follows. That is, the copper concentration is 60 g/L or more and 85 g/L or less (more preferably 50 g/L or more and 70 g/L or less), and the sulfuric acid concentration is 100 g/L or more and 250 g/L or less (more preferably 200 g/L or more and 250 g/L or less). ), the chlorine concentration is 1 mg/L or more and 3 mg/L or less (more preferably 1 mg/L or more and 2 mg/L or less), and the concentration of gelatin as an additive is 0.3 mg/L or more and 5 mg/L or less (more preferably 1 mg/L or more). Use a sulfuric acid-based copper electrolyte adjusted to a temperature of 40°C to 60°C (more preferably 50°C to 60°C), and use DSA (dimensionally stable anode) as the anode. Electrolytic copper foil having a desired tensile strength can be preferably obtained by electrolyzing at a current density of 30 A/dm ² or more and 75 A/dm ² or less (more preferably 40 A/dm ² or more and 60 A/dm ² or less). can. As an additive, instead of gelatin, potassium iodide (iodine concentration: 1 mg/L or more and 10 mg/L or less) or polyethyleneimine with a molecular weight of 3000 or more (concentration: 30 mg/L or more and 200 mg/L or less) may be used. By adding gelatin or the like as an additive to the electrolytic solution and performing electrolytic foil forming while controlling the electrolytic conditions within the above range, it becomes easier to form a carrier having high tensile strength. Furthermore, when the carrier-attached copper foil is subjected to heat treatment, a decrease in the tensile strength of the carrier can be suppressed.

(2) Formation of release layer A release layer is formed on the carrier. The release layer may be either an organic release layer or an inorganic release layer. Preferred examples of the organic release layer and the inorganic release layer are as described above. The release layer may be formed by bringing a release layer component-containing solution into contact with at least one surface of the carrier to fix the release layer component to the surface of the carrier. When the carrier is brought into contact with the release layer component-containing solution, this contact may be carried out by dipping the carrier in the release layer component-containing solution, spraying the release layer component-containing solution, flowing down the release layer component-containing solution, or the like. In addition, it is also possible to adopt a method of forming a film with the release layer component by a vapor phase method such as vapor deposition or sputtering. Further, the release layer component may be fixed to the carrier surface by adsorption or drying of a solution containing the release layer component, or by electrodeposition of the release layer component in the solution containing the release layer component.

(3) Formation of metal foil A metal foil is formed on the release layer. For example, the metal foil may be formed by wet film forming methods such as electroless metal plating and electrolytic metal plating, dry film forming methods such as sputtering and chemical vapor deposition, or a combination thereof. Preferably, the ultra-thin copper foil is formed by electrolytic copper plating. In particular, from the viewpoint of improving the tensile strength of the ultra-thin copper foil, it is preferable that the conditions for electrolytically forming the ultra-thin copper foil are as follows. That is, the copper concentration is 40 g/L or more and 80 g/L or less (more preferably 50 g/L or more and 70 g/L or less), and the sulfuric acid concentration is 180 g/L or more and 260 g/L or less (more preferably 200 g/L or more and 250 g/L or less). ), a sulfuric acid-based copper electrolyte with the concentration of carboxybenzotriazole (CBTA) adjusted to more than 0 ppm and less than 200 ppm as an additive, and a DSA (dimensionally stable anode) as the anode, with a liquid temperature of 35°C or more and 60°C. ℃ or less (more preferably 40°C or more and 55°C or less), current density 3 A/dm ² or more and 80 A/dm ² or less (more preferably 5 A/dm ² or more and 80 A/dm ² or less, even more preferably 6 A/dm ² or more and 75 A) /dm ² or less), a desired electrolytic copper foil can be preferably obtained. The CBTA concentration in the electrolyte is more preferably 0.1 ppm or more and 100 ppm or less, even more preferably 0.1 ppm or more and 50 ppm or less, particularly preferably 0.1 ppm or more and 30 ppm or less, and most preferably 0.1 ppm or more and 10 ppm or less. be. By adding carboxybenzotriazole (CBTA) as an additive to the electrolytic solution and performing electrolytic foil forming by controlling the electrolytic conditions within the above range, it becomes easier to form metal foil with high tensile strength. . Further, when the carrier-attached copper foil is subjected to heat treatment, a decrease in the tensile strength of the metal foil can be suppressed.

If desired, the surface of the metal foil is subjected to roughening treatment, rust prevention treatment and/or silane coupling agent treatment to form a roughened layer consisting of a plurality of roughened particles, a rust prevention treatment layer and/or a silane coupling agent layer. may be formed. These processes are as described above.

Metal-clad laminate The carrier-attached metal foil of the present invention is preferably used for producing a metal-clad laminate for printed wiring boards. That is, according to a preferred embodiment of the present invention, a metal-clad laminate (more preferably a copper-clad laminate) including the above-mentioned carrier-attached metal foil is provided. A metal-clad laminate includes a metal foil with a carrier, which includes a carrier, a release layer, and metal foil in this order, and a surface of the metal foil of the metal foil with a carrier (the surface opposite to the release layer of the metal foil). and a resin layer. The preferred embodiments of the carrier-attached metal foil described above also apply to the carrier-attached metal foil included in the metal-clad laminate. The carrier-attached metal foil may be provided on one side or both sides of the resin layer. The resin layer contains a resin, preferably an insulating resin. Preferably, the resin layer is a prepreg and/or a resin sheet. Prepreg is a general term for composite materials in which a base material such as a synthetic resin plate, glass plate, glass woven fabric, glass nonwoven fabric, or paper is impregnated with synthetic resin. Preferred examples of the insulating resin include epoxy resin, cyanate resin, bismaleimide triazine resin (BT resin), polyphenylene ether resin, and phenol resin. Furthermore, examples of the insulating resin constituting the resin sheet include insulating resins such as epoxy resin, polyimide resin, and polyester resin. Further, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation properties. The thickness of the resin layer is not particularly limited, but is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and still more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and/or a resin sheet may be provided on the carrier-attached metal foil via a primer resin layer that is previously applied to the surface of the metal foil.

Printed Wiring Board The carrier-attached metal foil of the present invention is preferably used for producing a printed wiring board. That is, according to a preferred embodiment of the present invention, there is provided a printed wiring board provided with the above metal foil with a carrier, or a method for manufacturing the same. The printed wiring board according to this embodiment includes a layered structure in which a resin layer and a metal layer are laminated in this order. Further, the resin layer is as described above for the metal-clad laminate. In any case, a known layer structure can be used for the printed wiring board. Specific examples of printed wiring boards include single-sided or double-sided printed wiring boards in which the metal foil of the present invention is adhered to one or both sides of a prepreg and cured to form a laminate, and circuits are formed thereon, and multilayer printed wiring in which these are multilayered. Examples include boards. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc. in which a circuit is formed by forming the metal foil of the present invention on a resin film. As another specific example, a resin-coated metal foil is formed by applying the above-mentioned resin layer to the metal foil of the present invention, and the resin layer is laminated on the above-mentioned printed wiring board as an insulating adhesive layer, and then the metal foil is coated with the above-mentioned printed wiring board. Build-up wiring boards where circuits are formed using methods such as modified semi-additive method (MSAP) or subtractive method as all or part of the wiring layer, or circuits are formed using semi-additive method (SAP) by removing metal foil. Direct build-up on wafer, in which lamination of resin-coated metal foil and circuit formation are alternately repeated on a semiconductor integrated circuit. The carrier-attached metal foil of the present invention can also be preferably used in a manufacturing method using a coreless build-up method in which insulating resin layers and conductor layers are alternately laminated without using a so-called core substrate.

The present invention will be explained in more detail with reference to the following examples.

Examples 1 to 11
A carrier-attached copper foil was produced and evaluated as follows.

(1) Preparation of carrier For Examples 1 to 6 and 11, a copper electrolyte having the composition shown below, a cathode, and a DSA (dimensionally stable anode) as an anode were used at a solution temperature of 50°C and a current of Electrolysis was carried out at a density of 60 A/dm ² to obtain an electrolytic copper foil of a predetermined thickness as a carrier.
<Composition of copper electrolyte>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 250g/L
- Chlorine concentration: 1.5mg/L
- Gelatin concentration: 2mg/L

On the other hand, for Examples 7 to 10, a copper electrolyte having the composition shown below, a cathode, and a DSA (dimensionally stable anode) as an anode were used at a solution temperature of 50°C and a current density of 70A/ ^dm2 . Electrolysis was performed to obtain an electrolytic copper foil of a predetermined thickness as a carrier.
<Composition of copper electrolyte>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 300g/L
- Chlorine concentration: 30mg/L
- Glue concentration: 5mg/L

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

(3) Formation of auxiliary metal layer The carrier on which the organic release layer was formed was immersed in a solution containing 20 g/L of nickel prepared using nickel sulfate at a liquid temperature of 45°C, pH 3, and a current density of 5 A/L. Nickel was deposited on the organic release layer in an amount equivalent to a thickness of 0.001 μm under conditions of dm ² . In this way, a nickel layer was formed as an auxiliary metal layer on the organic release layer.

(4) Formation of ultra-thin copper foil The carrier on which the ^auxiliary metal layer has been formed is immersed in a copper solution having the composition shown ^below . Examples 1 to 10) or 70 A/dm ² (Example 11) to form an ultra-thin copper foil of a predetermined thickness on the auxiliary metal layer.
<Solution composition>
- Copper concentration: 60g/L
- Sulfuric acid concentration: 200g/L
- CBTA concentration: 5.0 ppm (Examples 1, 4-8 and 11) or 0 ppm (Examples 2, 3, 9 and 10)

(5) Roughening treatment The surface of the ultra-thin copper foil thus formed was subjected to a roughening treatment to form a roughened copper foil, thereby obtaining a carrier-attached copper foil. This roughening treatment consists of a baking plating process in which fine copper grains are precipitated and adhered to the ultra-thin copper foil, and a covering plating process to prevent the fine copper grains from falling off. In the baking process, 9-phenylacridine (9PA) and chlorine are added to an acidic copper sulfate solution at a temperature of 25°C containing a copper concentration of 10 g/L and a sulfuric acid concentration of 200 g/L so that the 9PA concentration is 60 ppm and the chlorine concentration is 50 ppm. and roughening treatment was performed at a current density of 20 A/dm ² . In the subsequent cover plating step, electrodeposition was performed using an acidic copper sulfate solution containing a copper concentration of 70 g/L and a sulfuric acid concentration of 240 g/L under smooth plating conditions of a liquid temperature of 52° C. and a current density of 15 A/dm ² .

(6) Rust prevention treatment The roughened surface of the obtained carrier-attached copper foil was subjected to rust prevention treatment consisting of zinc-nickel alloy plating treatment and chromate treatment. First, using a solution containing a zinc concentration ^of 1 g/L, a nickel concentration of 2 g/L, and a potassium pyrophosphate concentration of 80 g/L, the roughened layer and carrier were The surface was subjected to zinc-nickel alloy plating treatment. Next, the surface subjected to the zinc-nickel alloy plating treatment was subjected to chromate treatment using an aqueous solution containing 1 g/L of chromic acid under conditions of pH 12 and current density of 1 A/dm ² .

(7) Silane coupling agent treatment A silane coupling agent treatment is performed by adsorbing an aqueous solution containing a commercially available silane coupling agent on the surface of the roughened copper foil side of the carrier-coated copper foil, and evaporating the water using an electric heater. I did it. At this time, the carrier side was not treated with a silane coupling agent.

(8) Heat Treatment For Examples 3 and 10, the carrier-attached copper foil treated with the silane coupling agent was heat treated at 175° C. for 5 minutes. On the other hand, for Examples 1, 2, and 4 to 9, this heat treatment was not performed.

(9) Evaluation Various characteristics of the carrier-attached copper foil thus obtained were evaluated as follows.

(9a) Thickness The thickness of each of the carrier and ultra-thin copper foil included in the carrier-attached copper foil was measured as follows. First, a carrier-attached copper foil was cut into a 100 mm square, and its weight _WA was measured using an electronic balance. Next, the carrier was peeled off from the carrier-attached copper foil, and the weight _WB of the carrier was measured using an electronic balance. Then, the thickness of the carrier is calculated from the weight W _B and the specific gravity of copper, and the thickness of the ultra-thin copper foil is calculated from the difference between the weights W _A and W _B (=W _A - W _B ) and the specific gravity of copper. did. The results were as shown in Table 1.

(9b) Normal tensile strength The tensile strength of the carrier and ultra-thin copper foil was measured as follows. First, the tensile strength TS ₃ (kgf/mm ² ) of the carrier-attached copper foil was measured in accordance with IPC-TM650 2.4.18. Next, the carrier was peeled off from the carrier-attached copper foil, and the tensile strength TS ₁ (kgf/mm ² ) of the carrier was measured in accordance with IPC-TM650 2.4.18. Since it is difficult to measure the tensile strength of ultra-thin copper foil using a similar method due to its thinness, the tensile strength 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 test piece are defined as TS ₃ '(kgf) and TS ₁ '(kgf), and the The tensile strength of the ultra-thin copper foil was defined as the value calculated by the formula (TS ₃ ′-TS ₁ ′)/A, where the cross-sectional area of the test piece was A (mm ² ). The results were as shown in Table 1.

(9c) Tensile strength after heating Prior to measuring tensile strength, the copper foil with a carrier was heat-treated in an oven at 250°C for 60 minutes in the air, and then allowed to cool to room temperature. The tensile strength after heating of the carrier and the ultra-thin copper foil was measured by the same procedure as the normal tensile strength described above. For Examples 2, 3, 9, and 10, only the tensile strength after heating of the carrier was measured, and the tensile strength after heating of the ultra-thin copper foil was not calculated. Further, in Example 11, the tensile strength of the carrier and the ultra-thin copper foil after heating was not measured. The results were as shown in Table 1.

(9d) Measurement of the number of cracks As an index of the tear resistance of ultra-thin copper foil, the number of cracks was measured as follows. First, as shown in FIG. 2, the carrier-attached copper foil was cut into a 150 mm square. Next, one side of the cut out carrier-attached copper foil 30 was fixed to a width of 25 mm. Then, one side opposite to the one fixed side was grasped, and the carrier-attached copper foil 30 was twisted twice in each direction. As shown in FIGS. 3(i) to (iii), this twisting was performed from a state in which the carrier-attached copper foil 30 was horizontal until it was at an angle of 45° with respect to the horizontal plane. After releasing the fixation, the carrier-attached copper foil 30 was rotated 90 degrees, and the above-mentioned twist imparting step was performed again. In this way, the twist imparting step was performed on all four sides of the carrier-attached copper foil 30. After that, as shown in FIG. 2, the number of cracks that occurred on the surface of the ultra-thin copper foil was measured using an optical microscope in a test area of 100 mm x 100 mm (=1 dm ² ), which is the center of the cut out copper foil with carrier 30. It was counted at. The above operation was performed three times for each example, and the average value was taken as the number of cracks. The results were as shown in Table 1.

Claims

A carrier-attached metal foil comprising a carrier, a release layer, and a metal foil in this order,
A metal foil with a carrier, wherein the carrier has a tensile strength of 50.0 kgf/mm 2 or more, and the metal foil has a tensile strength of 50.0 kgf/mm 2 or more.
After heating at 250° C. for 60 minutes, the carrier has a tensile strength of 45.0 kgf/mm 2 or more, and/or the metal foil has a tensile strength of 45.0 kgf/mm 2 or more. Metal foil with carrier as described.
The metal foil with a carrier according to claim 1 or 2, wherein the carrier and the metal foil are both copper foils.
The metal foil with a carrier according to claim 1 or 2, wherein the carrier has a thickness of 6 μm or more and 18 μm or less.
The metal foil with a carrier according to claim 1 or 2, wherein the metal foil has a thickness of 0.1 μm or more and 6 μm or less.
1 . The metal foil further comprises at least one layer selected from the group consisting of a roughening layer composed of a plurality of roughening particles, a rust prevention treatment layer, and a silane coupling agent layer. Or the metal foil with a carrier according to 2.
The metal foil with a carrier according to claim 1 or 2, further comprising an auxiliary metal layer between the release layer and the carrier and/or the metal foil.
A metal-clad laminate comprising the carrier-attached metal foil according to claim 1 or 2.
A printed wiring board comprising the carrier-attached metal foil according to claim 1 or 2.
A method for manufacturing a printed wiring board, comprising manufacturing a printed wiring board using the carrier-attached metal foil according to claim 1 or 2.