Method for manufacturing a printed circuit board and printed circuit board

Abstract

The manufacturing method of the printed circuit board of the present invention includes the following steps: a step of preparing a metal foil-clad laminate in which a metal foil having an arbitrary thickness (D b ) within the range of 3 to 20 μm and an insulating resin layer are laminated; a step of forming an anti-etching layer on the surface of the metal foil; a step of exposing and developing the anti-etching layer to form an anti-etching pattern; a step of etching the metal foil in the portion where the anti-etching pattern is not formed by spraying an etching solution to form a metal wiring; and a step of removing the anti-etching layer. In the step of forming the metal wiring, the gap (S) between the metal wirings includes 15 to 50 μm, and the ratio (S / D b ) of the gap (S) between the metal wirings to the arbitrary thickness (D b ) of the metal foil exceeds 1.6 to form the metal wiring in such a manner.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a printed circuit board and a printed circuit board. Background Art

[0002] Printed circuit boards and substrates for mounting semiconductor elements, which are widely used in electronic devices, communication devices, personal computers, etc., generally include: an insulating resin layer, and a conductor layer having a wiring pattern formed on the insulating resin layer. With the increase in the number of wirings accompanying the high functionality of electronic devices, etc., and the miniaturization of electronic devices, etc., miniaturization (refinement) of the metal wiring pattern is required. As a method for forming the metal wiring pattern, a subtractive method, etc. are known, and as an example of the subtractive method, the following method can be cited: a resist is used to selectively remove the conductor layer, thereby forming a metal wiring pattern. As an etching method in the subtractive method, there is wet etching. In wet etching, the etching solution infiltrates from the opening of the resist pattern to the conductor layer, thereby etching the conductor layer.

[0003] Patent Document 1 describes a method for manufacturing a wiring circuit board using wet etching in the subtractive method.

[0004] In addition, Patent Document 2 describes the following method for forming an electronic circuit. That is, it describes the following method for forming an electronic circuit: in a method for forming an electronic circuit by etching a copper-clad laminate, first, a layer having a slow etching rate of nickel or a nickel alloy is formed on the etching surface side of a copper layer formed of a rolled copper foil or an electrolytic copper foil. After that, the non-etching side surface of the copper layer is adhered to a resin substrate to form a copper-clad laminate, and then, after forming the copper layer and the nickel or nickel alloy layer, a resist pattern for circuit formation is given. Further, an etching solution formed of a ferric chloride solution is used to remove unnecessary portions of the copper layer and the nickel or nickel alloy layer on the copper-clad laminate other than the portion with the resist pattern. Then, the resist is removed, and further, the remaining nickel layer is removed by soft etching to form a circuit.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-125560

[0008] Patent Document 2: Japanese Re-Published Patent No. 2010-074054 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in the formation of a metal wiring pattern, in the etching in the subtractive method, the metal portion of the metal foil wiring after etching is etched so as to expand from the surface of the metal foil to the end of the insulating resin layer. Therefore, so-called "sagging" occurs, and it is difficult to form a wiring with a uniform and fine gap between the metal wirings. In addition, in the wiring circuit board in which "sagging" has occurred, short circuits sometimes occur in the wirings near the insulating resin layer.

[0011] In this regard, according to the manufacturing method of a wiring circuit board described in Patent Document 1, fine wiring can be formed. However, in the method described in Patent Document 1, a patterned conductor layer is formed from a conductor layer by first wet etching, and then a wiring circuit board is obtained by second wet etching. Therefore, two wet etchings are required. As a result, the process is complicated, the manufacturing time of the wiring circuit board becomes long, and the productivity is poor.

[0012] Furthermore, in the method for forming an electronic circuit described in Patent Document 2, in the process of forming the electronic circuit, the resist layer and the layer having a slow etching rate formed of nickel or a nickel alloy cannot be completely removed by soft etching, and dissolution residues are generated. Therefore, in the method of Patent Document 2, it is also difficult to form a wiring with a uniform and fine gap between the metal wirings. In addition, although a ferric chloride solution is used as the soft etching solution, ferric chloride cannot be completely removed and remains, and as a result, there is also a problem of causing migration.

[0013] The present invention has been made in view of such problems, and an object thereof is to provide: a manufacturing method of a printed circuit board capable of manufacturing a printed circuit board having a uniform gap between metal wirings and fine wirings with high productivity, and a printed circuit board.

[0014] Means for Solving the Problems

[0015] The inventors of the present invention have repeatedly conducted in-depth studies to solve the above problems, and as a result, have found that: in the manufacturing method of a printed circuit board using the subtractive method, the above problems can be solved by a manufacturing method including the following steps. Thus, the present invention has been completed. The steps are as follows: spraying an etching solution by spraying, so that the gap (S) between the metal wirings and the ratio (S / D b ) of the gap (S) between the metal wirings to any thickness (D b ) of the metal foil forming the metal wiring are respectively within specific ranges, and etching the metal foil of the portion where the resist pattern is not formed to form the metal wiring.

[0016] That is, the present invention is as follows. [1]

[0018] A manufacturing method of a printed circuit board, which includes the following steps:

[0019] A process for preparing a metal foil-clad laminate, wherein the metal foil-clad laminate is laminated with a metal foil having an arbitrary thickness (D b ) within the range of 3 to 20 μm and an insulating resin layer;

[0020] A process of forming an anti-etching layer on the surface of the aforementioned metal foil;

[0021] A process of exposing and developing the aforementioned anti-etching layer to form an anti-etching pattern;

[0022] A process of spraying an etching solution to etch the aforementioned metal foil of the portion where the aforementioned anti-etching pattern is not formed to form a metal wiring; and,

[0023] A process of removing the aforementioned anti-etching layer,

[0024] In the aforementioned process of forming the metal wiring, the gap (S) between the aforementioned metal wirings includes 15 to 50 μm, and the ratio (S / D b ) of the gap (S) between the aforementioned metal wirings to the arbitrary thickness (D b ) of the aforementioned metal foil exceeds 1.6 to form the aforementioned metal wiring. [2]

[0026] The method for manufacturing a printed circuit board according to [1], wherein the aforementioned etching is performed by spraying air together with the etching solution. [3]

[0028] The method for manufacturing a printed circuit board according to [1] or [2], wherein, in the aforementioned process of forming the anti-etching pattern, the gap (R) between the aforementioned anti-etching patterns is formed in a manner that is 1 to 5 μm narrower than the gap (S) between the aforementioned metal wirings. [4]

[0030] The method for manufacturing a printed circuit board according to any one of [1] to [3], wherein the aforementioned printed circuit board continuously has two or more gaps (US) having the same width as the gap (S) between the metal wirings formed in the gap (U) between the metal wirings formed on the aforementioned metal foil. [5]

[0032] The method for manufacturing a printed circuit board according to any one of [1] to [4], wherein, in the aforementioned process of forming the metal wiring, the width (W b ) of the aforementioned metal wiring is made equal to the gap (S) between the aforementioned metal wirings ((W b ) = (S)). [6]

[0034] The manufacturing method of a printed circuit board according to any one of [1] to [5], wherein, in the step of preparing the metal foil-clad laminate, the metal foil has a thickness adjusted to any thickness within the range of 3 to 20 μm (D b ) and is obtained in this way. [7]

[0036] The manufacturing method of a printed circuit board according to any one of [1] to [6], wherein the thickness of the resist layer formed on the surface of the metal foil is 15 μm or less. [8]

[0038] The manufacturing method of a printed circuit board according to any one of [1] to [7], wherein, in the step of forming the metal wiring, the metal wiring is formed such that the length (L) of the metal wiring is 100 μm or more. [9]

[0040] The manufacturing method of a printed circuit board according to any one of [1] to [8], wherein the metal foil is a copper foil.

[10]

[0042] A printed circuit board having: an insulating resin layer and metal wirings laminated on the insulating resin layer,

[0043] the thickness (D) of the metal wiring is 3 to 20 μm,

[0044] the gap (U) between the metal wirings is 12 to 50 μm,

[0045] the width (W) of the metal wiring is 12 to 50 μm,

[0046] the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring is 1.0 or more,

[0047] the average gap (U ave ) between the metal wirings and the average thickness (D ave ) of the metal wiring, the ratio (U ave / D ave ) is 1.60 to 1.80,

[0048] the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring is 1.0 or more, and

[0049] the average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring, the ratio (W ave / D ave) is 1.60 to 1.80.

[0050] Effects of the Invention

[0051] According to the manufacturing method of the present invention, a printed circuit board with uniform gaps between metal wirings and fine wirings can be manufactured with high productivity. In addition, according to the present invention, a printed circuit board with uniform gaps between metal wirings and fine wirings can be provided. Description of the Drawings

[0052] Figure 1 It is a schematic diagram showing the outline of the manufacturing method of the printed circuit board in the present embodiment.

[0053] Figure 2 It is a schematic diagram showing the gap (R) between the resist patterns in the process of forming the resist pattern of the present embodiment.

[0054] Figure 3 It is a schematic diagram showing the gap (S) between the metal wirings, any thickness (D b and D) of the first metal foil, and the width (W b and W) of the metal wiring of the first metal foil in the process of forming the metal wiring of the present embodiment. Detailed Description of the Invention

[0055] Hereinafter, the mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail with reference to the drawings as needed, but the present invention is not limited to the present embodiment. The present invention can be variously modified without departing from its gist. In the drawings, the same reference numerals are given to the same elements, and redundant explanations are omitted. In addition, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise particularly limited. Further, the dimensional ratios in the drawings are not limited to the ratios shown. In this specification, the laminate is formed by bonding each layer, and each layer can be a layer that can be peeled from each other as needed.

[0056] Regarding the manufacturing method and the printed circuit board of the printed circuit board, based on Figures 1 to 3 it will be described. Figure 1 It is a schematic diagram showing the outline of the manufacturing method of the printed circuit board in the present embodiment.

[0057] 〔Manufacturing Method of Printed Circuit Board〕

[0058] The manufacturing method of the printed circuit board of the present embodiment is as Figure 1 shown, and includes the following steps:

[0059] A step of preparing a metal foil-clad laminate in which a metal foil having an arbitrary thickness (D b ) in the range of 3 to 20 μm is laminated with an insulating resin layer;

[0060] A step of forming a resist layer on the surface of the aforementioned metal foil;

[0061] A step of exposing and developing the aforementioned resist layer to form a resist pattern;

[0062] A step of etching the aforementioned metal foil of the portion where the aforementioned resist pattern is not formed by spraying an etching solution to form a metal wiring; and,

[0063] A step of removing the aforementioned resist layer,

[0064] In the step of forming the aforementioned metal wiring, the gap (S) between the aforementioned metal wirings includes 15 to 50 μm, and the ratio (S / D b ) of the gap (S) between the aforementioned metal wirings to any thickness (D b ) of the aforementioned metal foil exceeds 1.6 to form the aforementioned metal wiring.

[0065] According to the manufacturing method of the printed circuit board, a printed circuit board with uniform gaps between metal wirings and fine wirings can be manufactured with high productivity.

[0066] (A step of preparing a metal foil-clad laminate, the metal foil-clad laminate laminating a metal foil having an arbitrary thickness (D b ) within the range of 3 to 20 μm and an insulating resin layer)

[0067] Figure 1 (a) is a schematic diagram for showing a metal foil-clad laminate in which a first metal foil 11, an insulating resin layer 10, and a second metal foil 12 are laminated in sequence. In the present embodiment, a metal foil-clad laminate is prepared, and the metal foil-clad laminate laminates a metal foil having an arbitrary thickness (D b ) within the range of 3 to 20 μm and an insulating resin layer.

[0068] (Metal foil-clad laminate)

[0069] As the metal foil-clad laminate, as shown in Figure 1 (a), it is possible to use: a metal foil-clad laminate 21 in which a first metal foil 11 having an arbitrary thickness (D b ) within the range of 3 to 20 μm and an insulating resin layer 10 are laminated in sequence. The metal foil-clad laminate 21, as shown in Figure 1 (a), may laminate a second metal foil 12 on the surface of the insulating resin layer 10 opposite to the surface on which the first metal foil 11 is laminated.

[0070] · Metal foil

[0071] From the aspect of easy processability, the first metal foil 11 has an arbitrary thickness (D b ) within the range of 3 to 20 μm. The arbitrary thickness (D b ) is preferably a uniform thickness. In this case, the variation in thickness is calculated using the average thickness of the first metal foil 11, as well as the maximum and minimum thicknesses, and the arbitrary thickness (D b ) is preferably in the range of 0 to 25% relative to the average thickness. For the arbitrary thickness (D b ), for example, when using a copper foil as the metal foil, it can be measured using a surface copper film thickness measuring instrument (Model 700 (trade name)) manufactured by Oxford Instruments. Additionally, for other metal foils, for example, it can be measured using a fluorescent X-ray film thickness meter (SFT3400 (trade name)) manufactured by Hitachi High-Tech Science Corporation. By having such a first metal foil 11, a printed circuit board with uniform gaps between metal wirings and fine wirings can be obtained.

[0072] The arbitrary thickness (D b ) can be adjusted by known methods. For example, using a peroxysulfuric acid-based soft etching solution such as SE-07 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd. and CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd., the surface of the first metal foil 11 is etched so as to have an arbitrary thickness (D b ) within the range of 3 to 20 μm, and thus it can also be obtained.

[0073] In addition, the second metal foil 12 preferably has an arbitrary thickness (d b ) within the range of 3 to 20 μm. The arbitrary thickness (d b ) is more preferably a uniform thickness. In this case, the variation in thickness is further preferably 0 to 25% of the average thickness of the second metal foil 12. The measurement of the arbitrary thickness (d b ) is the same as described above. The thicknesses of the first metal foil 11 and the second metal foil 12 can be the same or different on both sides, but are preferably the same. Additionally, the thickness of the second metal foil 12 can be adjusted by the same method as the adjustment of the thickness of the aforementioned first metal foil 11.

[0074] Examples of the first metal foil 11 and the second metal foil 12 include: gold, silver, copper, aluminum, and alloys formed by two or more of these metals. From the aspect of conductivity, copper is preferred. The first metal foil 11 and the second metal foil 12 can be the same or different, but are preferably the same.

[0075] As the first metal foil 11 and the second metal foil 12, for example, commercially available products such as GHY5 (trade name, 12 μm thick copper foil) and JXUT-1 (trade name, 1.5 μm thick copper foil) manufactured by JX Nippon Mining & Metals Co., Ltd., 3EC-M2S-VLP (trade name, 12 μm thick copper foil), 3EC-VLP (trade name, 12 μm thick copper foil), and 3EC-III (trade name, 12 μm thick copper foil) manufactured by Mitsui Mining & Smelting Co., Ltd., and GTS-MP (trade name, 12 μm thick copper foil) manufactured by Furukawa Electric Co., Ltd. can also be used.

[0076] · Insulating resin layer

[0077] The insulating resin layer 10 generally contains: a thermosetting resin, an inorganic filler, and, if necessary, a glass cloth. The thickness of the insulating resin layer 10 is generally 1 to 200 μm, and preferably 1 to 100 μm from the viewpoint of ease of handling of the substrate.

[0078] The thermosetting resin is not particularly limited as long as it is a thermosetting resin for printed circuit board materials. As specific examples, compounds such as cyanate ester compounds, epoxy resins, maleimide compounds, polyimide resins, and double bond addition polyphenylene ether resins can be cited. They can be appropriately selected according to the target use and performance, and one kind or a combination of two or more kinds can be used. As preferred thermosetting resins, cyanate ester compounds and epoxy resins can be cited.

[0079] The cyanate ester compound is not particularly limited as long as it has two or more cyanate ester groups in one molecule. As specific examples, bisphenol A type cyanate ester compounds, phenol novolac type cyanate ester compounds, bisphenol E type cyanate ester compounds, cyanate ester compounds containing a naphthalene skeleton, and cyanate ester compounds containing a biphenyl skeleton can be cited. They can be appropriately selected according to the target use and performance, and one kind or a combination of two or more kinds can be used. As preferred cyanate ester compounds, 2,2-bis(4-cyanatophenyl)propane, bis(3,5-dimethyl-4-cyanatophenyl)methane, phenol novolac type cyanate ester compounds, and naphthol aralkyl type cyanate ester compounds can be cited.

[0080] The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule. Specific examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, polyfunctional phenol type epoxy resin, naphthalene skeleton-containing epoxy resin, biphenyl skeleton-containing epoxy resin, and phosphorus-containing epoxy resin. They can be appropriately selected according to the target use and performance, and one kind can be used or two or more kinds can be used in combination. Preferred epoxy resins include bisphenol A type epoxy resin, phenol novolac type epoxy resin, biphenyl aralkyl type epoxy resin, naphthalene type epoxy resin, naphthol aralkyl type epoxy resin, and trifunctional phenol type epoxy resin.

[0081] The maleimide compound is not particularly limited as long as it is a compound having two or more maleimide groups in one molecule. Specific examples include bis(4-maleimidophenyl)methane, 2,2-bis{4-(4-maleimidophenoxy)phenyl}propane, bis(3,5-dimethyl-4-maleimidophenyl)methane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, bis(3,5-diethyl-4-maleimidophenyl)methane, polyphenylmethane maleimide. It should be noted that they can also be compounded in the form of prepolymers of these maleimide compounds, or prepolymers of maleimide compounds and amine compounds. They can be appropriately selected according to the target use and performance, and one kind can be used or two or more kinds can be used in combination. Preferred maleimide compounds include bis(3-ethyl-5-methyl-4-maleimidophenyl)methane.

[0082] As the polyimide resin, generally known substances can be used. Specifically, reaction products of polyfunctional maleimides and polyamines, and polyimide compounds having terminal triple bonds described in Japanese Patent Publication No. 57-005406 can be cited. These polyimide resins can be used singly or in combination of two or more.

[0083] Examples of the double bond-added polyphenylene ether resin include poly(2,6-dimethyl-1,4-phenylene ether), or those obtained by reacting a random copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol with an unsaturated fatty acid carboxylic acid or its anhydride. These double bond-added polyphenylene ether resins can be used singly or in combination of two or more.

[0084] As the inorganic filler materials, the following can be used: metal oxides such as silica, boron nitride, wollastonite, talc, kaolin, clay, mica, alumina, zirconia, titanium dioxide, barium titanate, and magnesium oxide; nitrides, silicides, borides, etc. They can be appropriately selected according to the target use and performance, and one kind can be used or two or more kinds can be used in combination. By including the inorganic filler materials, the reduction of the coefficient of thermal expansion and the rigidity in the printed circuit board can be improved. In particular, by adding inorganic filler materials with a low dielectric constant such as silica, boron nitride, and barium titanate, the insulating resin layer 10 can be made to have a low dielectric constant.

[0085] As the glass cloth, E glass cloth, NE glass cloth, D glass cloth, T glass cloth, Q glass cloth, quartz glass cloth, etc. can be used. These glass cloths can be used singly or in combination of two or more kinds.

[0086] As the insulating resin layer 10, commercially available products such as GHPL-830NX A-IT56 (trade name, thickness: 100 μm) manufactured by Mitsubishi Gas Chemical Company, Inc. can also be used, for example.

[0087] As the metal-clad laminate 21, commercially available products such as HL-830NS (trade name), HL-830NXA (trade name), HL-830NSF (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc. can also be used, for example.

[0088] · Adhesive layer

[0089] In the present embodiment, an adhesive layer for bonding them can be provided between the first metal foil 11 or the second metal foil 12 and the insulating resin layer 10, respectively, and a metal foil with an adhesive layer can also be used. As the material of the adhesive layer, acrylic resin, epoxy resin, polyimide resin, polyester resin, etc. can be used, for example.

[0090] · Resin sheet with metal foil

[0091] In the present embodiment, a resin sheet with a metal foil in which a metal foil and an insulating resin layer are laminated in sequence can also be used. In addition, the following can also be used: a metal-clad laminate 21 in which a metal foil is bonded to the surface of the insulating resin layer of the resin sheet and the first metal foil 11 and the second metal foil 12 are laminated on both sides of the insulating resin layer 10. As the resin sheet with a metal foil, commercially available products such as CRS-381NS1 (trade name, resin sheet with copper foil) manufactured by Mitsubishi Gas Chemical Company, Inc. can also be used, for example.

[0092] The thickness of the metal-clad laminate 21 is generally 3 to 236 μm, preferably 3 to 224 μm, more preferably 3 to 136 μm, and further preferably 3 to 124 μm.

[0093] (Hole opening and plating process)

[0094] Figure 1 (b) is a schematic diagram for showing a metal-clad laminate 22 in which a first metal foil 11 and a second metal foil 12 are electrically connected. In the present embodiment, for the metal-clad laminate 21, opening processing of via holes and / or through holes is performed as needed. For example, as shown in Figure 1 (b), the first metal foil 11 and the second metal foil 12 are electrically connected, and a first metal foil 11 having an arbitrary thickness (D b ) and the thickness of the second metal foil 12 as needed are also adjusted to an arbitrary thickness (D b ) can be used for the metal-clad laminate 22. In the present embodiment, the metal-clad laminate 22 can be used as a metal-clad laminate in which a metal foil having an arbitrary thickness (D ) can be used for the metal-clad laminate 22. In the present embodiment, the metal-clad laminate 22 can be used as a metal-clad laminate in which a metal foil having an arbitrary thickness (D b ) in the range of 3 to 20 μm and an insulating resin layer are laminated.

[0095] When using the metal-clad laminate 21, after performing a metal plating treatment, in order to adjust the first metal foil 11 to an arbitrary thickness (D b ), the thickness of the second metal foil 12 is also adjusted to an arbitrary thickness (d b ) as needed. Preferably, in a manner that is easy to adjust the thickness, for example, a peroxysulfuric acid-based soft etching solution such as SE-07 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc. and CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc. is used to etch the surface of the first metal foil 11 and the surface of the second metal foil 12 as needed in advance. In this case, it is more preferable to perform etching in advance so that the thicknesses of both the first metal foil 11 and the second metal foil 12 are in the range of 3 to 20 μm.

[0096] The opening processing is usually performed using a mechanical drill, a carbon dioxide gas laser, a UV laser, a YAG laser, etc.

[0097] When performing the opening processing, thereafter, a roughening treatment including a desmearing treatment can also be performed. It should be noted that generally, the roughening treatment includes a swelling process, a surface roughening and a desmearing process, and a neutralization process.

[0098] The swelling process is performed by swelling the surface of the insulating resin layer using a swelling agent. As the swelling agent, as long as the wettability of the surface of the insulating resin layer is improved and the surface of the insulating resin layer can be swollen to a degree that promotes oxidative decomposition in the subsequent surface roughening and desmearing processes, there is no particular limitation. As an example, an alkali solution, a surfactant solution, etc. can be cited.

[0099] The surface roughening and smear removal processes are carried out using an oxidizing agent. As the oxidizing agent, for example, an alkaline permanganate solution or the like can be cited. As a suitable specific example, an aqueous solution of potassium permanganate, an aqueous solution of sodium permanganate, etc. can be cited. The above-mentioned oxidizing agent treatment is called wet smear removal. In addition to this wet smear removal, dry smear removal using plasma treatment, UV treatment, mechanical grinding using an abrasive, sandblasting, and other known roughening treatments can also be appropriately combined and implemented.

[0100] The neutralization process is a process of neutralizing the oxidizing agent used in the previous process with a reducing agent. As the reducing agent, an amine-based reducing agent can be cited. As a suitable specific example, acidic aqueous solutions such as an aqueous solution of hydroxylamine sulfate, an aqueous solution of ethylenediaminetetraacetic acid, and an aqueous solution of nitrilotriacetic acid can be cited.

[0101] After forming vias and / or through-holes, or after performing smear removal treatment on the vias and / or through-holes, in order to electrically connect the respective conductor layers, it is preferable to perform metal plating treatment. In addition, in the present embodiment, even when vias and / or through-holes are not provided, metal plating treatment can be directly performed on the first metal foil 11 laminated on the metal foil-clad laminate 21 and the second metal foil 12 as required (both the metal foil 11 and the metal foil 12 can be the metal foils after the aforementioned etching).

[0102] As a method of metal plating treatment, a method of metal plating treatment in the manufacture of a general multi-layer printed circuit board can be appropriately used. The method of metal plating treatment and the type of chemical solution used in plating can be appropriately the method of metal plating treatment and chemical solution in the manufacture of a general multi-layer printed circuit board. The chemical solution used in metal plating treatment can be a commercially available product.

[0103] As a method of metal plating treatment, for example, the following can be cited: treatment using a degreasing solution, treatment using a soft etching solution, acid cleaning, treatment using a pre-impregnation solution, treatment using a catalytic solution, treatment using an accelerator solution, treatment using a chemical copper solution, acid cleaning, and treatment of dipping in a copper sulfate solution and passing an electric current.

[0104] As a specific example of the method of metal plating treatment, the following method can be cited: After forming a chemical coating film on the inner wall of the via and / or the inner wall of the through-hole by ordinary electroless plating treatment, the via and / or the through-hole are filled by electroplating methods such as a spraying plating method in which a plating solution is sprayed and blown onto the metal foil-clad laminate. As electroless plating or electroplating, metal plating is preferably performed, such as copper plating, tin plating, silver plating, various solders, copper and tin, copper and silver, etc., and electroless copper plating or electroplating copper is more preferable. For specific methods, reference can be made to the examples.

[0105] The thicknesses of the first metal foil 11 and the second metal foil 12 obtained by metal plating may be the same or different on both sides, but are preferably the same. In addition, the thicknesses of the first metal foil 11 and the second metal foil 12 obtained by metal plating are adjusted to any thickness (D b ) and any thickness (d b ) by the same method as the adjustment of the thickness of the aforementioned first metal foil 11. It should be noted that, in this case, any thickness (D b ) of the first metal foil 11 becomes the sum of the thickness of the metal foil laminated on the metal-clad laminate 21 (which may be the thickness of the metal foil after etching) and the thickness of the metal plating layer obtained by metal plating. The same applies to any thickness (d b ) of the second metal foil 12. In addition, the preferred range of the thicknesses of the first metal foil 11 and the second metal foil 12 is the same as described above.

[0106] (Process of forming an anti-corrosion layer on the surface of the metal foil)

[0107] Figure 1 (c) is a schematic diagram for showing the metal-clad laminate 23 on which the first anti-corrosion layer 13 and the second anti-corrosion layer 14 are formed. In the present embodiment, as shown in Figure 1 (c), it includes: a process of forming the first anti-corrosion layer 13 on the surface of the first metal foil 11. Through this process, the metal-clad laminate 23 on which the first anti-corrosion layer 13 is formed on the surface of the first metal foil 11 can be obtained.

[0108] The first anti-corrosion layer 13 is coated on the whole of the metal-clad laminate 21 or the metal-clad laminate 22 so as to cover the first metal foil 11 in the metal-clad laminate 21 or the metal-clad laminate 22. If necessary, the second anti-corrosion layer 14 can be formed on the surface of the second metal foil 12 in the same manner as the first anti-corrosion layer 13.

[0109] In addition, in the present embodiment, before forming the first anti-corrosion layer 13 and the second anti-corrosion layer 14, the alignment holes described later can be provided.

[0110] As the material for forming the first anti-corrosion layer 13, an anti-corrosion agent with excellent developability is preferably used. As such an anti-corrosion agent, commercially available products can be used. For example, RD-1225 (trade name), RD-1215 (trade name), RY-5319 (trade name), RD-2010 (trade name), RY-5115 (trade name), etc. manufactured by Hitachi Chemical Co., Ltd. can be cited. It should be noted that the same material can also be used for the second anti-corrosion layer 14.

[0111] The thicknesses of the first resist layer 13 and the second resist layer 14 are not particularly limited as long as they can be dissolved and removed by etching the first metal foil 11 and the second metal foil 12. From the aspect of obtaining better resolution, the thicknesses of the first resist layer 13 and the second resist layer 14 are preferably 15 μm or less, more preferably 1 to 13 μm, and still more preferably 1 to 10 μm. The thicknesses of the first resist layer 13 and the second resist layer 14 may be the same or different, but are preferably the same.

[0112] The first resist layer 13 and the second resist layer 14 can be formed by using known methods used in the manufacture of printed circuit boards. For example, the first resist layer 13 and the second resist layer 14 can be formed by the subtraction method described later.

[0113] (Process of exposing and developing the resist layer to form a resist pattern)

[0114] Figure 1 (d) is a schematic diagram of the metal-clad laminate 24 in which resist patterns are formed on the first resist layer 13 and the second resist layer 14 respectively. In the present embodiment, as shown in Figure 1 (d), it includes: a process of exposing and developing the first resist layer 13 to form a resist pattern. Through this process, the metal-clad laminate 24 having a resist pattern formed on the first resist layer 13 can be obtained. The resist pattern can be formed at an appropriate position according to the wiring pattern.

[0115] In the present embodiment, considering the influence of etching on the width direction of the metal wiring, the gap (R) between the resist patterns is preferably formed so as to be 1 to 5 μm narrower than the gap (S) between the metal wirings described later, and more preferably formed so as to be 2 to 4 μm narrower. The gap (R) between the resist patterns, as shown in Figure 2 , refers to the width 41 in the gap of the resist pattern, and the resist pattern is preferably formed on the first resist layer 13 so as to have the gap (R).

[0116] In addition, similarly, considering the influence of etching on the width direction of the metal wiring, the gap (r) between the resist patterns is preferably formed so as to be 1 to 5 μm narrower than the gap (s) between the metal wirings described later, and more preferably formed so as to be 2 to 4 μm narrower. The gap (r) between the resist patterns is the same as the gap (R) between the resist patterns, which refers to the width in the gap of the resist pattern, and the resist pattern is preferably formed on the second resist layer 14 so as to have the gap (r). Regarding the measurement method of the gap (R) and (r) between the resist patterns, reference can be made to the aforementioned thickness (D b ) and (d b ) and the examples.

[0117] In this embodiment, as needed, the second resist layer 14 is exposed and developed in the same manner as the resist pattern of the first resist layer 13, and a resist pattern can be formed. In this case, the resist pattern is formed at an appropriate position according to the wiring pattern.

[0118] The formation of the first resist layer 13 and the resist pattern based on the subtractive method can be carried out as follows, for example. On the surface of the first metal foil 11 and, as needed, on the surface of the second metal foil 12, a dry film resist (for example, RD-1225 (trade name) and RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) is laminated and attached (laminated) at a temperature of 110 ± 10 °C and a pressure of 0.50 ± 0.02 MPa to form the first resist layer 13 and, as needed, the second resist layer 14. Then, the first resist layer 13 is exposed and masked along the circuit pattern. Additionally, as needed, in the second resist layer 14, exposure and masking are also carried out along the circuit pattern. After that, the dry film resist is developed in a 1% sodium carbonate aqueous solution, thereby forming a resist pattern in the first resist layer 13. Additionally, as needed, the dry film resist is developed in a 1% sodium carbonate aqueous solution, thereby forming a resist pattern in the second resist layer 14 as well. Thus, a metal foil-clad laminate 24 having a resist pattern formed thereon can be formed.

[0119] In this embodiment, from the aspect of being able to shorten the manufacturing time of the wiring circuit board and obtain good productivity, as Figure 1 shown in (d), it is preferable to form a resist pattern by a spraying method of spraying a developing solution such as a sodium carbonate aqueous solution and a potassium carbonate aqueous solution on the dry film resist.

[0120] The spraying can use a well-known spraying used in the manufacture of printed circuit boards. In this embodiment, from the aspect of being able to manufacture a printed circuit board with uniform gaps between metal wirings and having fine wirings with high productivity and being able to form a resist pattern of fine lines, it is more preferable to form a resist pattern by spraying air together with the developing solution. The spraying is preferably carried out at a spraying pressure of the developing device of 0.05 to 1.5 MPa for a spraying time of 10 to 120 seconds. Additionally, the spraying pressure of the developing device is preferably 0.07 to 1.2 MPa. The spraying time is preferably 20 to 100 seconds.

[0121] As the spraying for spraying air together with the developing solution, a spraying having, for example, two fluid nozzles is preferable.

[0122] (The step of etching the metal foil of the portion where the resist pattern is not formed by spraying an etching solution to form metal wirings)

[0123] Figure 1(e) is a schematic diagram of a metal-clad laminate 25 in which metal wirings are formed on a first metal foil 11 and a second metal foil 12, respectively. In the present embodiment, as shown in Figure 1 (e), it includes a step of etching the first metal foil 11 of a portion where no resist pattern is formed by spraying an etching solution to form a metal wiring on the first metal foil 11. In the step of forming the metal wiring, the gap (S) between the metal wirings includes 15 to 50 μm, and the ratio (S / D b ) of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 exceeds 1.6 to form the metal wiring. Through this step, a metal-clad laminate 25 with a metal wiring formed thereon can be obtained. In addition, by including this step, a printed circuit board with a uniform gap between metal wirings and having fine wirings can be obtained.

[0124] The gap (S) between the metal wirings, as shown in Figure 3 , refers to the width 42 in the gap between the metal wirings, and this width 42 is in the range of 15 to 50 μm. In the present embodiment, the metal wiring is formed on the first metal foil 11 in such a manner as to have the gap (S). In the present embodiment, it can be formed in such a manner as to have a gap between metal wirings having a width other than the gap (S), that is, a gap between metal wirings having a width less than 15 μm and / or more than 50 μm. It should be noted that for the lower limit and the upper limit of the width of this gap, generally the lower limit is 10.5 μm and the upper limit is 1000 μm. From the aspect of high-density wiring, the gap (S) between the metal wirings is preferably formed in the range of 15 to 35 μm. In this case, it can be formed in such a manner as to have a gap between metal wirings having a width less than 15 μm and / or more than 35 μm.

[0125] In addition, in the present embodiment, similar to the gap (S) between the metal wirings, metal wirings may be formed on the second metal foil 12 so as to have a gap (s). The gap (s) between the metal wirings refers to the width in the gaps of the metal wirings formed on the second metal foil 12, and this width is generally preferably 15 to 50 μm. In the present embodiment, it may be formed to have: a gap between the metal wirings having a width other than the gap (s), that is, a gap between the metal wirings having a width less than 15 μm and / or more than 50 μm. It should be noted that for the lower limit and the upper limit of the width of this gap, generally the lower limit is 10.5 μm and the upper limit is 1000 μm. From the aspect of high-density wiring, the gap (s) between the metal wirings is preferably formed to be 15 to 35 μm. In this case, it may be formed to have: a gap between the metal wirings having a width less than 15 μm and / or more than 35 μm. Regarding the measurement method of the gaps (S) and (s) between the metal wirings, reference may be made to the aforementioned thickness (D b ) and (d b ) and the examples.

[0126] Any thickness (D b ) of the first metal foil 11, as Figure 3 shown, refers to the thickness 43 from the surface of the insulating resin layer 10 to the first metal foil 11. Regarding any thickness (D b ) and the preferred range, as described above.

[0127] Similarly, any thickness (d b ) of the second metal foil 12 refers to the thickness from the surface of the insulating resin layer 10 to the second metal foil 12. Regarding any thickness (d b ) and the preferred range, as described above.

[0128] The metal wirings are formed such that the ratio (S / D b ) of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 exceeds 1.6. Preferably, the metal wirings are formed such that (S / D b ) is 1.6 to 3.0, and more preferably, the metal wirings are formed such that (S / D b ) is 1.6 to 2.5. By forming the metal wirings such that the ratio (S / D b ) is within the aforementioned range, the etching between the wirings becomes sufficient. Therefore, high-density wiring becomes possible and insulation defects such as short circuits are less likely to occur.

[0129] Similarly, preferably, the ratio (s / d b ) of the gap (s) between the metal wirings to any thickness (d b)Form the metal wiring in a manner exceeding 1.6, more preferably in a manner where (s / d b ) is 1.6 to 3.0, and even more preferably in a manner where (s / d b ) is 1.6 to 2.5. Form the metal wiring in a manner where the ratio of (s / d b ) is within the aforementioned range, so that the etching between wirings becomes sufficient. Therefore, high-density wiring becomes possible, and it is less likely to cause insulation defects such as short circuits.

[0130] In the process of forming the metal wiring, from the aspect of high-density of the metal wiring for transmitting electrical signals, it is preferable to form the metal wiring on the first metal foil 11 in a manner where the width (W b ) of the metal wiring and the gap (S) between the metal wirings are the same ((W b ) = (S)), and it is more preferable to form the metal wiring in exactly the same manner. The width (W b ) of the metal wiring, as shown in Figure 3 , refers to the width 44 in the metal wiring. It is preferable to form the metal wiring on the first metal foil 11 in a manner having this width (W b ).

[0131] Similarly, from the aspect of high-density of the metal wiring for transmitting electrical signals, it is preferable to form the metal wiring on the second metal foil 12 in a manner where the width (w b ) of the metal wiring and the gap (s) between the metal wirings are the same ((w b ) = (s)), and it is more preferable to form the metal wiring in exactly the same manner. The width (w b ) of the metal wiring, like the width (W b ) of the metal wiring, refers to the width in the metal wiring. It is preferable to form the metal wiring on the second metal foil 12 in a manner having this width (w b ). Regarding the measurement method of the width (W b ) and (w b ), reference can be made to the aforementioned thickness (D b ) and (d b ) and the examples.

[0132] In the process of forming the metal wiring, from the aspects of being able to form long wirings, facilitating the routing around pads, vias, etc., and increasing the design freedom, it is preferable to form the metal wiring on the first metal foil 11 in a manner where the length (L) in the length direction of the metal wiring is 100 μm or more. For the upper limit, it is, for example, 10 mm.

[0133] In addition, similarly, from the aspect that it becomes easy to form long wirings, and to wind wirings around pads, vias, etc., and the degree of freedom in design is improved, the length (l) in the length direction of the metal wiring is preferably formed on the second metal foil 12 in a manner of 100 μm or more. For the upper limit, it is, for example, 10 mm. Regarding the measuring method of the lengths (L) and (l) in the length direction of the metal wiring, reference can be made to the aforementioned thickness (D b ) and (d b ) and the examples.

[0134] In the present embodiment, if necessary, metal wirings are also formed on the second metal foil 12 in the same manner as on the first metal foil 11.

[0135] The formation of the metal wiring can be performed as follows. As Figure 1 (e) shows, on the first resist layer 13 and, if necessary, the second resist layer 14, the first metal foil 11 and the second metal foil 12 of the portions where no resist pattern is formed are etched to remove the metal foil. The etching is performed by spraying an etching solution. By performing the etching by spraying, the etching is not extended to the end of the insulating resin layer from the metal foil, and no so-called "dripping" occurs. Therefore, the gaps between the metal wirings are uniform, and fine wirings can be formed.

[0136] The spray can be a known spray used in the manufacture of printed circuit boards. In the present embodiment, from the aspect that a printed circuit board with uniform gaps between metal wirings and fine wirings can be manufactured with high productivity, it is preferable to perform the etching by spraying air together with the etching solution. The spray is preferably performed at an etching rate of 0.05 to 1.5 μm / second for a spraying time of 20 to 120 seconds. It should be noted that the etching rate is described as the etching amount per unit time in the thickness direction when etching the metal foil by spraying.

[0137] As the spray for spraying air together with the etching solution, for example, a spray having two fluid nozzles is preferably used. The flow rate of the etching solution in the two fluid nozzles is preferably 0.5 to 3.5 L / minute, more preferably 1.5 to 2.5 L / minute. In addition, the flow rate of the air is preferably 100 to 400 L / minute, more preferably 200 to 300 L / minute.

[0138] As the etching solution, a known etching solution used in the manufacture of printed circuit boards can be used, and for example, an aqueous copper chloride solution (a mixed solution of copper concentration: 120 to 180 g / L and hydrochloric acid concentration: 100 to 150 g / L) can be cited.

[0139] (Process of removing the resist layer)

[0140] Figure 1(f) is a schematic diagram showing the metal-clad laminate 26 with the first resist layer 13 and the second resist layer 14 removed. In the present embodiment, as shown in Figure 1 (f), it includes: a process of removing the first resist layer 13. Through this process, the metal-clad laminate 26 with the first resist layer 13 removed can be obtained. When the second resist layer 14 is formed, the second resist layer 14 is removed to obtain the metal-clad laminate 26.

[0141] The removal of the first resist layer 13 and the second resist layer 14 can use a known method in the manufacture of printed circuit boards and is not particularly limited. For example, it can use: a method of stripping a dry film resist with an aqueous potassium hydroxide solution and an amine-based resist stripper.

[0142] (Process of providing via holes and / or through holes)

[0143] In the present embodiment, as needed, in order to electrically connect each metal foil (conductor layer), it may include a process of performing opening processing of via holes and / or through holes. In addition, when performing opening processing, afterwards, roughening processing including desmear treatment may be performed. Regarding the opening processing and the roughening processing, reference can be made to the foregoing.

[0144] After providing via holes and / or through holes, or after performing desmear treatment on the via holes and / or through holes, in order to electrically connect each conductor layer, metal plating treatment is preferably performed. Regarding the metal plating treatment, reference can be made to the foregoing.

[0145] (Process of providing alignment holes)

[0146] In the present embodiment, for the purpose of alignment for exposure for forming a wiring pattern, it may appropriately include a process of providing alignment holes. At this time, it is preferable to further provide holes around the alignment holes. The method of forming the alignment holes and the holes around the alignment holes can use a known opening method in the manufacture of ordinary printed circuit boards. For example, it can use: a method of performing opening processing with a drill and a method of performing opening with X-rays or a laser.

[0147] [Printed circuit board]

[0148] According to this embodiment, through the foregoing steps, a metal wiring having a predetermined thickness (D) and width (W) is formed from the first metal foil 11, and a metal wiring having a predetermined thickness (d) and width (w) is formed from the second metal foil 12 as needed. Then, a metal foil-clad laminate 26 and a printed circuit board having the metal foil-clad laminate 26 can be obtained. The metal foil-clad laminate 26 includes: a metal wiring having a predetermined thickness (D) and width (W), and a predetermined wiring pattern having a predetermined gap (U) between the metal wirings. As needed, it includes: a metal wiring having a predetermined thickness (d) and width (w), and a predetermined wiring pattern having a predetermined gap (u) between the metal wirings. The metal foil-clad laminate 26 and the printed circuit board can each have a via hole and / or a through hole.

[0149] In the printed circuit board of this embodiment, the gaps between the metal wirings are uniform and have fine wirings. Therefore, preferably, it has an insulating resin layer and metal wirings laminated on the insulating resin layer. The thickness (D) of the metal wiring is 3 to 20 μm, the gap (U) between the metal wirings is 12 to 50 μm, the width (W) of the metal wiring is 12 to 50 μm, the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring is 1.0 or more, and the average gap (U ave ) between the metal wirings and the average thickness (D ave ) of the metal wiring, the ratio (U ave / D ave ) is 1.60 to 1.80. The ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring is 1.0 or more, and the average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring, the ratio (W ave / D ave ) is 1.60 to 1.80. In the printed circuit board, the surface of the first metal foil 11 has a predetermined metal wiring and a predetermined wiring pattern having a predetermined gap between the metal wirings. As needed, the surface of the second metal foil 12 can have a predetermined metal wiring and a predetermined wiring pattern having a predetermined gap between the metal wirings. The printed circuit board can be used for various electronic components such as semiconductor devices.

[0150] Regarding the insulating resin layer and the metal wiring, reference can be made to the foregoing.

[0151] From the aspect of high density of the metal wirings for transmitting electrical signals, the thicknesses (D) and (d) of the metal wirings are each in the range of 3 to 20 μm. The thicknesses (D) and (d) are as Figure 3As shown, it refers to the thickness 43 from the surface of the insulating resin layer 10 to the metal wiring. The thicknesses (D) and (d) of the metal wiring are preferably uniform thicknesses, and more preferably the same as any of the thicknesses (D b ) in the first metal foil 11 and any of the thicknesses (d b ) in the second metal foil 12. The variation of the thickness (D) is calculated using the average thickness of the thickness (D), and the maximum and minimum thicknesses. The thickness (D) is preferably in the range of 0 to 25% with respect to the average thickness. Similarly for the thickness (d), it is preferably in the range of 0 to 25% with respect to the average thickness. Regarding the material, thickness, and measurement method of the variation of the metal wiring, reference can be made to the aforementioned thicknesses (D b ) and (d b ) and the examples.

[0152] From the aspect of high density of the metal wiring for transmitting electrical signals, the gaps (U) and (u) between the metal wirings are respectively in the range of 12 to 50 μm. The gaps (U) and (u) between the metal wirings are respectively the gaps between the metal wirings formed in the first metal foil 11 and the gaps between the metal wirings formed in the second metal foil 12. In this embodiment, the gaps (U) and (u) are set as the widths on the surface of the insulating resin layer as the gaps (S) and (s) shown Figure 3 .

[0153] For the metal-clad laminate 26 and the printed circuit board, from the aspect of high density of the metal wiring for transmitting electrical signals, it is preferably continuously provided with: two or more gaps (US) having the same width as the gap (S) between the metal wirings in the gap (U) between the metal wirings formed in the first metal foil 11, more preferably three or more continuously, and further preferably four or more continuously. Regarding the upper limit, for example, it is 100.

[0154] Also, similarly, for the metal-clad laminate 26 and the printed circuit board, from the aspect of high density of the metal wiring for transmitting electrical signals, it is preferably continuously provided with: two or more gaps (us) having the same width as the gap (s) between the metal wirings in the gap (u) between the metal wirings formed in the second metal foil 12, more preferably three or more continuously, and further preferably four or more continuously. Regarding the upper limit, for example, it is 100.

[0155] From the aspect of high density of the metal wiring for transmitting electrical signals, the widths (W) and (w) of the metal wirings are respectively in the range of 12 to 50 μm. The widths (W) and (w) of the metal wiring are as shown Figure 3 , and refer to the width 44 in the metal wiring.

[0156] From the aspect that there are narrow portions in the gap between metal wirings and insulation failure is caused in these portions, the ratio (U / D) of the gap (U) between metal wirings to the thickness (D) of the metal wiring, and the ratio (u / d) of the gap (u) between metal wirings to the thickness (d) of the metal wiring are each 1.0 or more, preferably 1.2 or more. The upper limit is not particularly limited, for example, each is 2.4 or less. It should be noted that the ratio (U / D) is calculated based on the ratio of the maximum thickness calculated from the thickness variation in the thickness (D) of the metal wiring to the minimum gap in the gap (U) between metal wirings. In addition, the ratio (u / d) is calculated in the same manner.

[0157] The average gap (U ave ) between metal wirings and the average thickness (D ave ) of the metal wiring, the ratio (U ave / D ave ), and the average gap (u ave ) between metal wirings and the average thickness (d ave ) of the metal wiring, the ratio (u ave / d ave ) are each 1.60 to 1.80. By having the ratio (U ave / D ave ) and the ratio (u ave / d ave ) within the aforementioned range, the gap between the metal foil clad laminate 26 and the metal wiring of the printed circuit board obtained is uniform and fine, and has good metal wiring.

[0158] From the aspect that the width of the metal wiring is narrow relative to the thickness of the metal wiring and insulation failure is caused, the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring, and the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring are each 1.0 or more, preferably 1.2 or more. The upper limit is not particularly limited, for example, each is 2.4 or less. It should be noted that the ratio (W / D) is calculated based on the ratio of the maximum thickness calculated from the thickness variation in the thickness (D) of the metal wiring and the minimum width in the width (W) between metal wirings. In addition, the ratio (w / d) is calculated in the same manner.

[0159] The average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring, the ratio (W ave / D ave ), and the average width (w ave ) of the metal wiring and the average thickness (d ave ) of the metal wiring, the ratio (w ave / d ave ) are each 1.60 to 1.80. By the ratio (Uave / D ave ) and ratio (w ave / d ave ) are within the aforementioned ranges, so that the gap between the metal foil-clad laminate 26 and the metal wiring of the printed circuit board is uniform and fine, and the metal wiring is excellent.

[0160] The average thickness of the metal wiring (D ave ) and (d ave ), the average gap between the metal wirings (U ave ) and (u ave ), and the average width of the metal wiring (W ave ) and (w ave ) are the respective average values of the thickness (D) and (d), the gap (U) and (u) between the metal wirings, and the width (W) and (w) of the metal wiring in the obtained metal foil-clad laminate 26 and the printed circuit board. Regarding the values of these thicknesses, gaps, and widths, and the average values, the specific measurement methods and calculation methods can refer to the aforementioned thickness (D b ) and (d b ) and the examples.

[0161] In addition, in the obtained metal foil-clad laminate 26 and the printed circuit board, the thickness (D) and (d) of the metal wiring, the gap (U) and (u) between the metal wirings, the width (W) and (w) of the metal wiring, the ratio (U / D) and the ratio (u / d), the ratio (U ave / D ave ) and the ratio (u ave / d ave ), the ratio (W / D) and the ratio (w / d), and the ratio (W ave / D ave ) and the ratio (w ave / d ave ) may be the same or different respectively. From the aspect of further reducing the occurrence of conduction failure of the metal wiring and insulation failure between the metal wirings, it is preferably the same.

[0162] Examples

[0163] Examples of this embodiment will be described using Figure 1 , but this embodiment is not limited by any of these examples.

[0164] 〔Evaluation Method〕

[0165] (1) Evaluation method for the thickness of the metal foil, the variation of the thickness, the gap between the resist patterns, the gap between the metal wirings, the length of the metal wiring, and the width of the metal wiring in the metal foil-clad laminate before wiring formation

[0166] Using a surface copper film thickness measuring instrument (Model 700 (trade name)) manufactured by Oxford Instruments, measure the thickness (D b ) of the first metal foil 11 in the metal foil-clad laminate before wiring formation, and calculate the average thickness. From the maximum thickness, minimum thickness, and average thickness in the thickness (D b ) of the first metal foil 11, calculate the thickness variation. Similarly, measure the thickness (d b ) of the second metal foil 12 in the metal foil-clad laminate before wiring formation, and calculate the thickness variation. In addition, measure the thickness (d b ) of the second metal wiring in the metal foil-clad laminate after wiring formation, and calculate the average thickness and thickness variation. Similarly, using a surface copper film thickness measuring instrument (Model 700 (trade name)) manufactured by Oxford Instruments, measure the gaps (R) and (r) between the resist patterns, the gaps (S) and (s) between the metal wirings, the lengths (L) and (l) of the metal wirings, and the widths (W b ) and (w b ) of the metal wirings.

[0167] (2) Evaluation method for the thickness of the metal wiring, the gap between the metal wirings, the width of the metal wiring, the average thickness of the metal wiring, the average gap between the metal wirings, the average width of the metal wiring, the ratio (U / D), the ratio (W / D), the ratio (U ave / D ave ), and the ratio (W ave / D ave ) in the metal foil-clad laminate after wiring formation

[0168] After cross-section grinding the metal foil-clad laminate after wiring formation, observe it through a microscope (magnification: 500 times), and measure the thickness (D) of the metal wiring formed on the first metal foil 11, the gap (U) between the metal wirings, and the width (W) of the metal wiring respectively. From these values, obtain the average thickness (D ave ) of the metal wiring, the average gap (U ave ) between the metal wirings, and the average width (W ave ) of the metal wiring. In addition, calculate the thickness variation from the maximum thickness, minimum thickness, and average thickness (D ave ) in the thickness (D) of the metal wiring. From these values, calculate the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring, the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring, and the ratio (U ave ) of the average gap (U ave ) between the metal wirings to the average thickness (D ave ) of the metal wiring (U / Dave ) and the ratio (W ave ) of the average width of the metal wiring to the average thickness (D ave ) of the metal wiring (W ave / D ave ).

[0169] In addition, similarly, the thickness (d) of the metal wiring formed on the second metal foil 12, the gap (u) between the metal wirings, and the width (w) of the metal wiring are respectively measured, and from these values, the average thickness (d ave ) of the metal wiring, the average gap (u ave ) between the metal wirings, and the average width (w ave ) of the metal wiring are obtained. In addition, the variation in thickness is calculated from the maximum thickness, the minimum thickness, and the average thickness (d ave ) in the thickness (d) of the metal wiring. From these values, the ratio (u / d) of the gap (u) between the metal wirings to the thickness (d) of the metal wiring, the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring, the ratio (u ave ) of the average gap (u) between the metal wirings to the average thickness (d ave ) of the metal wiring (u ave / d ave ), and the ratio (w ave ) of the average width (w) of the metal wiring to the average thickness (d ave ) of the metal wiring (w ave / d ave ) are respectively calculated.

[0170] (3) Evaluation of the gaps (U) and (u) between the metal wirings

[0171] Among the gaps (U) between the metal wirings obtained by the evaluation method in the above (2), the gap that deviates most from the design value is used. When this gap is within 30% of the gap (S) (design value), it is judged as good, and when it exceeds 30%, it is judged as bad. In addition, the gap (u) between the metal wirings obtained by the evaluation method in the above (2) is evaluated in the same way.

[0172] It should be noted that if the average value exceeds 30% of the design value, the risk of short - circuit with adjacent wirings or the risk of conduction failure caused by thinning of the metal wiring increases, so it is judged as bad.

[0173] (4) Evaluation of the continuity of the gaps (US) and (us) between the metal wirings

[0174] Count the gaps (US) having the same width as the gap (S) in the gaps (U) between the metal wirings obtained by the evaluation method described above (2), and evaluate the continuity. Similarly, evaluate the continuity of the gaps (u) between the metal wirings obtained by the evaluation method described above (2).

[0175] [Example 1]

[0176] As Figure 1 (a) shows, a metal-clad laminate 21 in which a copper foil (first metal foil 11, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm), an insulating resin layer 10 (GHPL-830NX A-IT56 (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc., thickness of the insulating resin layer 10: 100 μm), and a copper foil (second metal foil 12, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm) are sequentially laminated. For the first metal foil 11 and the second metal foil 12, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc.) is used to etch the surfaces of the first metal foil 11 and the second metal foil 12 so as to have thicknesses in the range of 3 to 5 μm, respectively.

[0177] Next, for the metal-clad laminate 21, a through-hole opening process is performed using a carbon dioxide gas (CO 2 ) laser processing machine (GTW-4 (trade name) manufactured by Mitsubishi Electric Corporation). For the metal-clad laminate having through-holes, after forming a plating layer with a thickness of 0.3 to 0.5 μm by electroless plating, a plating layer of 15 to 20 μm is applied by using copper sulfate (concentration: 60 to 80 g / L) and sulfuric acid (concentration: 150 to 200 g / L), thereby obtaining a metal-clad laminate in which the first metal foil 11 and the second metal foil 12 are electrically connected. For the first metal foil 11 and the second metal foil 12 in the metal-clad laminate, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc.) is used to etch the surfaces of the first metal foil 11 and the second metal foil 12 so as to have uniform thicknesses of 15 μm (D b ) and (d b )(variation in thickness: 25% respectively), as Figure 1 (b) shows, to obtain a metal-clad laminate 22.

[0178] Next, using a routing machine (manufactured by Hitachi Via Mechanics, Ltd.), holes for alignment are formed in the metal foil-clad laminate 22. Thereafter, on both surfaces of the metal foil-clad laminate 22 (the respective surfaces of the first metal foil 11 and the second metal foil 12), a dry film resist (RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) is laminated at a temperature of 110 ± 10°C and a pressure of 0.50 ± 0.02 MPa to form a first resist layer 13 (thickness: 10 μm) and a second resist layer 14 (thickness: 10 μm), as shown in Figure 1 (c), and a metal foil-clad laminate 23 is obtained.

[0179] Next, using the holes for alignment as a reference, with a parallel exposure machine (IP3650HH (trade name) manufactured by Adtech Engineering Co., Ltd.), the first resist layer 13 and the second resist layer 14 are exposed and masked along the circuit pattern such that the gaps (R) and (r) between the resist patterns are each 22 μm. Thereafter, using a spray device having two fluid nozzles (hybrid developing device (trade name) manufactured by Tokyo Kakoki Co., Ltd.), air is sprayed together with a 1% aqueous sodium carbonate solution (developer) at a spray pressure of 0.11 MPa for a spraying time of 25 seconds to develop the dry film resist, and resist patterns are formed in the first resist layer 13 and the second resist layer 14, respectively, as shown in Figure 1 (d), and a metal foil-clad laminate 24 is obtained. It should be noted that the obtained resist patterns are formed as parallel lines.

[0180] Next, with respect to the metal foil-clad laminate 24, using a spray device having two fluid nozzles (hybrid etching device (trade name) manufactured by Tokyo Kakoki Co., Ltd.), the gaps (S) and (s) between the respective metal wirings of the first metal foil 11 and the second metal foil 12 are each 25 μm (design value), the ratio (S / D b ) of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 is 1.67 (design value) and thus exceeds 1.6, the ratio (s / d b ) of the gap (s) between the metal wirings to any thickness (d b ) of the second metal foil 12 is 1.67 (design value) and thus exceeds 1.6, the length (L) of the metal wiring in the first metal foil 11 is 1000 μm, the length (l) of the metal wiring in the second metal foil 12 is 1000 μm, the width (W b ) of the metal wiring is exactly the same as the gap (S) between the metal wirings ((W b ) = (S)), the width (wb ) is exactly the same as the gap (s) between the metal wirings ((W b ) = (s)), at an etching solution flow rate of 2.0 L / minute and an air flow rate of 200 L / minute, with an etching rate of 0.7 μm / second, spray an etching solution of an aqueous copper chloride solution (a mixed solution with a copper concentration of 120 - 180 g / L and a hydrochloric acid concentration of 100 - 150 g / L) for 40 seconds, and etch the first metal foil 11 and the second metal foil 12 of the part where the resist pattern is not formed respectively to obtain a metal-clad laminate 25 having metal wirings on the first metal foil 11 and the second metal foil 12 respectively ( Figure 1 (e).

[0181] Next, use a 3% aqueous potassium hydroxide solution to strip and remove the first resist layer 13 and the second resist layer 14 to obtain a metal-clad laminate 26 ( Figure 1 (f).

[0182] Measure the obtained metal-clad laminate 26. As a result, on the surface of the first metal foil 11, the thickness (D) of the metal wiring is 15 μm (thickness variation: 25%), the average thickness (D ave ) is 15 μm, the gap (U) between the metal wirings is 25 ± 5 μm, the average gap (U ave ) between the metal wirings is 25 μm, the width (W) of the metal wiring is 25 ± 5 μm, the average width (W ave ) of the metal wiring is 25 μm, the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring is 1.067 (= (25 - 5) μm / (15 + 15×25%) μm), the average gap (U ave ) between the metal wirings and the average thickness (D ave ) of the metal wiring ratio (U ave / D ave ) is 1.67, the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring is 1.067 (= (25 - 5) μm / (15 + 15×25%) μm), the average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring ratio (W ave / D ave ) is 1.67. On the surface of the second metal foil 12, the thickness (d) of the metal wiring is 15 μm (thickness variation: 25%), the average thickness (d ave ) is 15 μm, the gap (u) between the metal wirings is 25 ± 5 μm, the average gap (u ave ) between the metal wirings is 25 μm, the width (w) of the metal wiring is 25 ± 5 μm, the average width (wave ) is 25 μm, the ratio (u / d) of the gap (u) between metal wirings to the thickness (d) of the metal wiring is 1.067 (= (25 - 5) μm / (15 + 15×25%) μm), and the average gap (u ave ) between metal wirings and the average thickness (d ave ) of the metal wiring, the ratio (u ave / d ave ) is 1.67, the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring is 1.067 (= (25 - 5) μm / (15 + 15×25%) μm), and the average width (w ave ) of the metal wiring and the average thickness (d ave ) of the metal wiring, the ratio (w ave / d ave ) is 1.67. In addition, the gap (U) between metal wirings is 25 ± 5 μm, and the gap (u) between metal wirings is 25 ± 5 μm. Therefore, the average values of the gaps (U) and (u) are within 30% of the design value (25 μm). Therefore, it was confirmed that the obtained metal-clad laminate 26 has good metal wirings. It was confirmed that in the obtained metal-clad laminate 26, there are 4 gaps (US) having the same width as the gap (S) (25 μm) continuously in the gap (U) between the metal wirings formed in the first metal foil 11, and there are 4 gaps (us) having the same width as the gap (s) (25 μm) continuously in the gap (u) between the metal wirings formed in the second metal foil 12. In the obtained metal-clad laminate, the minimum value of the width of the metal wiring is 20 μm.

[0183] Therefore, it was confirmed that the gaps between the metal wirings of the metal-clad laminate 26 are uniform and fine, and it has good metal wirings.

[0184] [Example 2]

[0185] As Figure 1 (a) shows, a metal-clad laminate 21 in which a copper foil (the first metal foil 11, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm), an insulating resin layer 10 (GHPL-830NX A-IT56 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd., thickness of the insulating resin layer 10: 100 μm), and a copper foil (the second metal foil 12, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm) are laminated in sequence was prepared. For the first metal foil 11 and the second metal foil 12, the surfaces of the first metal foil 11 and the second metal foil 12 were etched with a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd.) so as to have thicknesses in the range of 3 to 5 μm respectively.

[0186] For the metal-clad laminate 21, after forming a plating layer with a thickness of 0.3 to 0.5 μm on the first metal foil 11 and the second metal foil 12 respectively by electroless plating, a plating layer of 15 to 20 μm is applied to the first metal foil 11 and the second metal foil 12 respectively by copper sulfate plating using copper sulfate (concentration: 60 to 80 g / L) and sulfuric acid (concentration: 150 to 200 g / L), thereby obtaining a metal-clad laminate. For the first metal foil 11 and the second metal foil 12 in the metal-clad laminate, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.) is used to etch the surfaces of the first metal foil 11 and the second metal foil 12 respectively to have a uniform thickness of 9 μm (D b ) and (d b )(the variation in thickness: 20% respectively), as shown in Figure 1 (b), to obtain a metal-clad laminate 22 (wherein, there are no through holes and via holes).

[0187] Next, a positioning hole is formed in the metal-clad laminate 22 using a routing machine (manufactured by Hitachi Via Mechanics, Ltd.). After that, a dry film resist (RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) is laminated on both sides of the metal-clad laminate 22 (the surfaces of the first metal foil 11 and the second metal foil 12 respectively) at a temperature of 110 ± 10 °C and a pressure of 0.50 ± 0.02 MPa to form a first resist layer 13 (thickness: 10 μm) and a second resist layer 14 (thickness: 10 μm), as shown in Figure 1 (c), to obtain a metal-clad laminate 23 (wherein, there are no through holes and via holes).

[0188] Next, taking the positioning hole as a reference, the first resist layer 13 and the second resist layer 14 are exposed and masked along the circuit pattern using a parallel exposure machine (IP3650HH (trade name) manufactured by Adtech Engineering Co., Ltd.) such that the gaps (R) and (r) between the resist patterns are each 11 μm. After that, a spray device with two fluid nozzles (a hybrid developing device (trade name) manufactured by TokyoKakoki Co., Ltd.) is used to spray air together with a 1% sodium carbonate aqueous solution (developer) at a spray pressure of 0.11 MPa for a spraying time of 25 seconds to develop the dry film resist, and resist patterns are formed on the first resist layer 13 and the second resist layer 14 respectively, as shown in Figure 1 (d), to obtain a metal-clad laminate 24 (wherein, there are no through holes and via holes). It should be noted that the obtained resist patterns are formed as parallel lines.

[0189] Next, for the metal foil clad laminate 24, using a spraying device (a hybrid etching device (trade name) manufactured by Tokyo Kakoki Co., Ltd.) having two fluid nozzles, with the gaps (S) and (s) between the respective metal wirings of the first metal foil 11 and the second metal foil 12 being 15 μm (design value) respectively, and the ratio (S / D b ) of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 being 1.67 (design value), thus exceeding 1.6, and the ratio (s / d b ) of the gap (s) between the metal wirings to any thickness (d b ) of the second metal foil 12 being 1.67 (design value), thus exceeding 1.6, the length (L) of the metal wiring in the first metal foil 11 being 800 μm, the length (l) of the metal wiring in the second metal foil 12 being 800 μm, the width (W b ) of the metal wiring being exactly the same as the gap (S) between the metal wirings ((W b ) = (S)), and the width (w b ) of the metal wiring being exactly the same as the gap (s) between the metal wirings ((w b ) = (s)), the copper chloride aqueous solution (a mixed solution of copper concentration of 120 - 180 g / L and hydrochloric acid concentration of 100 - 150 g / L) is sprayed at an etching rate of 0.7 μm / second for 26 seconds with the flow rate of the etching solution being 2.0 L / minute and the flow rate of air being 200 L / minute to etch the first metal foil 11 and the second metal foil 12 of the parts where the resist pattern is not formed respectively, and a metal foil clad laminate 25( Figure 1 (e), where there are no vias and through vias) is obtained.

[0190] Next, the first resist layer 13 and the second resist layer 14 are peeled off and removed with a 3% potassium hydroxide aqueous solution to obtain a metal foil clad laminate 26( Figure 1 (f), where there are no vias and through vias).

[0191] The obtained metal foil clad laminate 26 is measured. As a result, on the surface of the first metal foil 11, the thickness (D) of the metal wiring is 9 μm (thickness variation: 20%), the average thickness (D ave ) of the metal wiring is 9 μm, the gap (U) between the metal wirings is 15 ± 3 μm, the average gap (U ave ) between the metal wirings is 15 μm, the width (W) of the metal wiring is 15 ± 3 μm, the average width (W ave) is 15 μm, the ratio (U / D) of the gap (U) between metal wirings to the thickness (D) of the metal wiring is 1.11, and the average gap (U ave ) between metal wirings and the average thickness (D ave ) of the metal wiring, the ratio (U ave / D ave ) is 1.67. The ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring is 1.11, and the average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring, the ratio (W ave / D ave ) is 1.67. On the surface of the second metal foil 12, the thickness (d) of the metal wiring is 9 μm (thickness variation: 25%), and the average thickness (d ave ) of the metal wiring is 9 μm. The gap (u) between metal wirings is 15 ± 3 μm, and the average gap (u ave ) between metal wirings is 15 μm. The width (w) of the metal wiring is 15 ± 3 μm, and the average width (w ave ) of the metal wiring is 15 μm. The ratio (u / d) of the gap (u) between metal wirings to the thickness (d) of the metal wiring is 1.11, and the average gap (u ave ) between metal wirings and the average thickness (d ave ) of the metal wiring, the ratio (u ave / d ave ) is 1.67. The ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring is 1.11, and the average width (w ave ) of the metal wiring and the average thickness (d ave ) of the metal wiring, the ratio (w ave / d ave ) is 1.67. In addition, the gap (U) between metal wirings is 15 ± 3 μm, and the gap (u) between metal wirings is 15 ± 3 μm. Therefore, the average values of the gaps (U) and (u) are within 30% of the design value (15 μm). Therefore, it is confirmed that the obtained metal-clad laminate 26 has good metal wirings. It is confirmed that in the obtained metal-clad laminate 26, there are 4 gaps (US) with the same width as the gap (S) (15 μm) continuously formed in the gap (U) between the metal wirings formed on the first metal foil 11, and there are 4 gaps (us) with the same width as the gap (s) (15 μm) continuously formed in the gap (u) between the metal wirings formed on the second metal foil 12. In the obtained metal-clad laminate, the minimum value of the width of the metal wiring is 12 μm.

[0192] Therefore, it was confirmed that the gaps between the metal wirings of the metal foil clad laminate 26 were uniform and fine, and that the metal wirings were excellent.

[0193] 〔Example 3〕

[0194] As Figure 1 (a) shows, a metal foil clad laminate 21 in which a copper foil (first metal foil 11, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm), an insulating resin layer 10 (GHPL-830NX A-IT56 (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc., thickness of the insulating resin layer 10: 100 μm), and a copper foil (second metal foil 12, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm) are laminated in sequence. For the first metal foil 11 and the second metal foil 12, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc.) was used to etch the surfaces of the first metal foil 11 and the second metal foil 12 so as to have uniform thicknesses (D b ) of 9 μm each and (d b )(variation in thickness: 15% each), and as Figure 1 (b) shows, a metal foil clad laminate 22 (wherein through holes and via holes are not provided) was obtained.

[0195] Next, a hole for alignment was formed in the metal foil clad laminate 22 using a routing machine (manufactured by Hitachi Via Mechanics, Ltd.). Thereafter, a dry film resist (RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) was laminated on both surfaces (the respective surfaces of the first metal foil 11 and the second metal foil 12) of the metal foil clad laminate 22 at a temperature of 110 ± 10°C and a pressure of 0.50 ± 0.02 MPa to form a first resist layer 13 (thickness: 10 μm) and a second resist layer 14 (thickness: 10 μm), and as Figure 1 (c) shows, a metal foil clad laminate 23 (wherein through holes and via holes are not provided) was obtained.

[0196] Next, using the alignment holes as a reference, the first resist layer 13 and the second resist layer 14 are exposed and masked along the circuit pattern by a parallel exposure machine (IP3650HH (trade name) manufactured by Adtech Engineering Co., Ltd.) in such a manner that the gaps (R) and (r) between the resist patterns are each 12 μm. Thereafter, a spray device having two fluid nozzles (hybrid developing device (trade name) manufactured by TokyoKakoki Co., Ltd.) sprays air together with a 1% aqueous sodium carbonate solution (developer) at a spray pressure of 0.11 MPa for a spraying time of 25 seconds to develop the dry film resist, and resist patterns are respectively formed on the first resist layer 13 and the second resist layer 14, as Figure 1 shown in (d), to obtain a metal foil-clad laminate 24 (wherein through holes and via holes are not provided). It should be noted that the obtained resist patterns are formed as parallel linear shapes.

[0197] Next, for the metal foil-clad laminate 24, a spray device having two fluid nozzles (hybrid etching device (trade name) manufactured by Tokyo KakokiCo., Ltd.) is used such that the gaps (S) and (s) between the respective metal wirings of the first metal foil 11 and the second metal foil 12 are each 15 μm (design value), the ratio of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 is (S / D b ) = 1.67 (design value), thus exceeding 1.6, the ratio of the gap (s) between the metal wirings to any thickness (d b ) of the second metal foil 12 is (s / d b ) = 1.67 (design value), thus exceeding 1.6, the length (L) of the metal wiring in the first metal foil 11 is 500 μm, the length (l) of the metal wiring in the second metal foil 12 is 500 μm, the width (W b ) of the metal wiring is exactly the same as the gap (S) between the metal wirings ((W b ) = (S)), and the width (w b ) of the metal wiring is exactly the same as the gap (s) between the metal wirings ((w b ) = (s)). At an etching solution flow rate of 2.0 L / minute and an air flow rate of 200 L / minute, an etching solution of copper chloride aqueous solution (a mixed solution of copper concentration of 120 - 180 g / L and hydrochloric acid concentration of 100 - 150 g / L) is sprayed for 22 seconds at an etching rate of 0.7 μm / second to etch the portions of the first metal foil 11 and the second metal foil 12 where the resist patterns are not formed, thereby obtaining a metal foil-clad laminate 25 having metal wirings respectively on the first metal foil 11 and the second metal foil 12 ( Figure 1(e), where there are no through holes and via holes).

[0198] Next, the first resist layer 13 and the second resist layer 14 are peeled off using a 3% aqueous potassium hydroxide solution to obtain the metal foil-clad laminate 26( Figure 1 (f), where there are no through holes and via holes).

[0199] The obtained metal foil-clad laminate 26 was measured. As a result, on the surface of the first metal foil 11, the thickness (D) of the metal wiring was 9 μm (thickness variation: 15%), the average thickness (D ave ) was 9 μm, the gap (U) between the metal wirings was 15 ± 1.5 μm, the average gap (U ave ) between the metal wirings was 15 μm, the width (W) of the metal wiring was 15 ± 1.5 μm, the average width (W ave ) of the metal wiring was 15 μm, the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring was 1.30, the average gap (U ave ) between the metal wirings and the average thickness (D ave ) of the metal wiring ratio (U ave / D ave ) was 1.67, the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring was 1.30, the average width (W ave ) of the metal wiring and the average thickness (D ave ) of the metal wiring ratio (W ave / D ave ) was 1.67. On the surface of the second metal foil 12, the thickness (d) of the metal wiring was 9 μm (thickness variation: 15%), the average thickness (d ave ) was 9 μm, the gap (u) between the metal wirings was 15 ± 1.5 μm, the average gap (d ave ) between the metal wirings was 15 μm, the width (w) of the metal wiring was 15 ± 1.5 μm, the average width (w ave ) of the metal wiring was 15 μm, the ratio (u / d) of the gap (u) between the metal wirings to the thickness (d) of the metal wiring was 1.30, the average gap (u ave ) between the metal wirings and the average thickness (d ave ) of the metal wiring ratio (u ave / d ave ) was 1.67, the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring was 1.30, the average width (w ave ) of the metal wiring and the average thickness (d ave ) of the metal wiring ratio (w ave / d ave) is 1.67. In addition, the gap (U) between the metal wirings is 15 ± 1.5 μm, and the gap (u) between the metal wirings is 15 ± 1.5 μm. Therefore, the average values of the gaps (U) and (u) are within 30% with respect to the design value (15 μm). Therefore, it was confirmed that the obtained metal foil-clad laminate 26 has good metal wirings. It was confirmed that in the obtained metal foil-clad laminate 26, there are continuously two gaps (US) having the same width as the gap (S) (15 μm) in the gap (U) between the metal wirings formed in the first metal foil 11, and there are continuously two gaps (us) having the same width as the gap (s) (15 μm) in the gap (u) between the metal wirings formed in the second metal foil 12. In the obtained metal foil-clad laminate, the minimum value of the width of the metal wiring is 13 μm.

[0200] Therefore, it was confirmed that the gaps between the metal wirings of the metal foil-clad laminate 26 are uniform and fine, and have good metal wirings.

[0201] 〔Comparative Example 1〕

[0202] A metal foil-clad laminate 21 in which a copper foil (the first metal foil 11, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm), an insulating resin layer 10 (GHPL-830NX A-IT56 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd., thickness of the insulating resin layer 10: 100 μm), and a copper foil (the second metal foil 12, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm) are laminated in sequence was prepared. For the first metal foil 11 and the second metal foil 12, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used to etch the surfaces of the first metal foil 11 and the second metal foil 12 so as to have thicknesses in the range of 3 to 5 μm, respectively.

[0203] Next, for the metal foil-clad laminate 21, via holes were drilled using a carbon dioxide gas (CO 2 ) laser processing machine (GTW-4 (trade name) manufactured by Mitsubishi Electric Corporation). For the metal foil-clad laminate having via holes, after forming a plating layer with a thickness of 0.3 to 0.5 μm by electroless plating, a plating layer of 15 to 20 μm was applied by electroplating copper sulfate (concentration: 60 to 80 g / L) and sulfuric acid (concentration: 150 to 200 g / L), thereby obtaining a metal foil-clad laminate in which the first metal foil 11 and the second metal foil 12 are electrically connected. For the first metal foil 11 and the second metal foil 12 in the metal foil-clad laminate, a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used to have uniform thicknesses of 18 μm (D b ) and (db )(The thickness variation: 25% respectively), etch the surfaces of the first metal foil 11 and the second metal foil 12 to obtain the metal-clad laminate 22.

[0204] Next, use a routing machine (manufactured by Hitachi Via Mechanics, Ltd.) to form alignment holes in the metal-clad laminate 22. After that, laminate a dry film resist (RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) on both sides of the metal-clad laminate 22 (the surfaces of the first metal foil 11 and the second metal foil 12 respectively) at a temperature of 110 ± 10 °C and a pressure of 0.50 ± 0.02 MPa to form the first resist layer 13 (thickness: 10 μm) and the second resist layer 14 (thickness: 10 μm), obtaining the metal-clad laminate 23.

[0205] Next, using the alignment holes as a reference, use a parallel exposure machine (IP3650HH (trade name) manufactured by Adtech Engineering Co., Ltd.) to expose and mask the first resist layer 13 and the second resist layer 14 along the circuit pattern such that the gaps (R) and (r) between the resist patterns are 22 μm respectively. After that, use a spraying device with two fluid nozzles (hybrid developing device (trade name) manufactured by Tokyo Kakoki Co., Ltd.) to spray air together with a 1% aqueous sodium carbonate solution (developer) at a spraying pressure of 0.11 MPa for a spraying time of 25 seconds to develop the dry film resist, obtaining the metal-clad laminate 24 with resist patterns formed on the first resist layer 13 and the second resist layer 14 respectively. It should be noted that the obtained resist patterns are formed as parallel lines.

[0206] Next, for the metal-clad laminate 24, use a spraying device with two fluids (hybrid etching device (trade name) manufactured by Tokyo Kakoki Co., Ltd.) such that the gaps (S) and (s) between the respective metal wirings of the first metal foil 11 and the second metal foil 12 are 25 μm (design value), the ratio of the gap (S) between the metal wirings to any thickness (D b ) is (S / D b ) is 1.39 (design value), so it is 1.6 or less, the ratio of the gap (s) between the metal wirings to any thickness (d b ) is (s / d b ) is 1.39 (design value), so it is 1.6 or less, the length (L) of the metal wiring in the first metal foil 11 is 1000 μm, the length (l) of the metal wiring in the second metal foil 12 is 1000 μm, the width (W b)The gap (S) with the metal wiring is exactly the same ((W b ) = (S)), the width (w b ) of the metal wiring is exactly the same as the gap (s) between the metal wirings ((w b ) = (s)). At an etching solution flow rate of 2.0 L / minute and an air flow rate of 200 L / minute, with an etching rate of 0.7 μm / second, an etching solution of copper chloride aqueous solution (a mixed solution with a copper concentration of 120 - 180 g / L and a hydrochloric acid concentration of 100 - 150 g / L) was sprayed for 40 seconds to etch the first metal foil 11 and the second metal foil 12 of the part where the resist pattern was not formed, respectively.

[0207] Next, the first resist layer 13 and the second resist layer 14 were stripped and removed with 3% potassium hydroxide aqueous solution to obtain the metal - clad laminate A.

[0208] In the obtained metal - clad laminate A, the metal parts of the metal wirings of the first metal foil 11 and the second metal foil 12 were etched to expand from the surface of the metal foil to the end of the insulating resin layer, resulting in so - called "sagging", and it was difficult to form wirings with uniform and fine gaps between the metal wirings. In addition, due to the occurrence of "sagging", short - circuits occurred in the wirings near the insulating resin layer.

[0209] 〔Comparative Example 2〕

[0210] In Comparative Example 1, short - circuits occurred in the wirings near the insulating resin layer. Therefore, the etching time based on the copper chloride aqueous solution and air was extended. That is, at an etching solution flow rate of 2.0 L / minute and an air flow rate of 200 L / minute, with an etching rate of 0.7 μm / second, an etching solution of copper chloride aqueous solution (a mixed solution with a copper concentration of 120 - 180 g / L and a hydrochloric acid concentration of 100 - 150 g / L) was sprayed for 50 seconds to etch the first metal foil 11 and the second metal foil 12 of the part where the resist pattern was not formed, respectively. Next, the first resist layer 13 and the second resist layer 14 were stripped and removed with 3% potassium hydroxide aqueous solution to obtain the metal - clad laminate B.

[0211] The obtained metal - clad laminate B was measured. As a result, on the surface of the first metal foil 11, the thickness (D) of the metal wiring was 18 μm (thickness variation: 25%), the average thickness (D ave ) of the metal wiring was 18 μm, the gap (U) between the metal wirings was 27 ± 6 μm, the average gap (U ave ) between the metal wirings was 27 μm, the width (W) of the metal wiring was 23 ± 6 μm, the average width (W ave ) of the metal wiring was 23 μm, the ratio (U / D) of the gap (U) between the metal wirings to the thickness (D) of the metal wiring was 0.93, the average gap (Uave ) ratio (U ave ) to the average thickness (D ave / D ave ) is 1.50, the ratio (W / D) of the width (W) of the metal wiring to the thickness (D) of the metal wiring is 0.76, and the ratio (W ave ) of the average width of the metal wiring to the average thickness (D ave ) is W ave / D ave ) is 1.28. On the surface of the second metal foil 12, the thickness (d) of the metal wiring is 18 μm (thickness variation: 25%), the average thickness (d ave ) of the metal wiring is 18 μm, the gap (u) between the metal wirings is 27 ± 6 μm, the average gap (u ave ) between the metal wirings is 27 μm, the width (w) of the metal wiring is 23 ± 6 μm, the average width (w ave ) of the metal wiring is 23 μm, the ratio (u / d) of the gap (u) between the metal wirings to the thickness (d) of the metal wiring is 0.93, and the ratio (u ave ) of the average gap (u) between the metal wirings to the average thickness (d ave ) of the metal wiring is u ave / d ave ) is 1.50, the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring is 0.76, and the ratio (w ave ) of the average width of the metal wiring to the average thickness (d ave ) of the metal wiring is w ave / d ave ) is 1.28. In addition, the gap (U) between the metal wirings is 27 ± 6 μm, and the gap (u) between the metal wirings is 27 ± 6 μm. Therefore, the average value of the gaps (U) and (u) is 32% with respect to the design value (25 μm). Therefore, there is a defect in the gap between the metal wirings.

[0212] In addition, in the obtained metal foil clad laminate, the minimum value of the width of the metal wiring becomes 17 μm. When the wiring width becomes narrow, the transmission loss of the electrical signal becomes large, and the risk of open circuit also increases.

[0213] 〔Comparative Example 3〕

[0214] A metal-clad laminate 21 is prepared by laminating in sequence a copper foil (the first metal foil 11, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm), an insulating resin layer 10 (GHPL-830NX A-IT56 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc., thickness of the insulating resin layer 10: 100 μm), and a copper foil (the second metal foil 12, 3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness: 12 μm). For the first metal foil 11 and the second metal foil 12, the surfaces of the first metal foil 11 and the second metal foil 12 are etched with a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.) to have thicknesses in the range of 3 to 5 μm respectively.

[0215] For the metal-clad laminate 21, after forming a plating layer with a thickness of 0.3 to 0.5 μm on the first metal foil 11 and the second metal foil 12 respectively by electroless plating, a plating layer of 15 to 20 μm is applied to the first metal foil 11 and the second metal foil 12 respectively by copper sulfate plating (concentration: 60 to 80 g / L) and sulfuric acid (concentration: 150 to 200 g / L), thereby obtaining a metal-clad laminate. For the first metal foil 11 and the second metal foil 12 in the metal-clad laminate, the surfaces of the first metal foil 11 and the second metal foil 12 are etched with a peroxysulfuric acid-based soft etching solution (CPE-700 (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc.) to have a uniform thickness of 11 μm (D b ) and (d b )(variation in thickness: 20% respectively) to obtain a metal-clad laminate 22 (wherein, there are no through holes and via holes).

[0216] Next, a registration hole is formed in the metal-clad laminate 22 using a routing machine (manufactured by Hitachi Via Mechanics, Ltd.). Thereafter, a dry film resist (RD-2010 (trade name) manufactured by Hitachi Chemical Co., Ltd.) is laminated on both sides of the metal-clad laminate 22 (the surfaces of the first metal foil 11 and the second metal foil 12 respectively) at a temperature of 110 ± 10 °C and a pressure of 0.50 ± 0.02 MPa to form a first resist layer 13 (thickness: 10 μm) and a second resist layer 14 (thickness: 10 μm), thereby obtaining a metal-clad laminate 23 (wherein, there are no through holes and via holes).

[0217] Next, using the alignment holes as a reference, the first resist layer 13 and the second resist layer 14 are exposed and masked along the circuit pattern by a parallel exposure machine (IP-3650HH (trade name) manufactured by Adtech Engineering Co., Ltd.) in such a manner that the gaps (R) and (r) between the resist patterns are each 11 μm. Thereafter, using a spraying device with two fluid nozzles (hybrid developing device (trade name) manufactured by TokyoKakoki Co., Ltd.), air is sprayed together with a 1% aqueous sodium carbonate solution (developer) at a spraying pressure of 0.11 MPa for a spraying time of 25 seconds to develop the dry film resist, thereby obtaining a metal-clad laminate 24 (wherein through-holes and via holes are not provided) having resist patterns formed on the first resist layer 13 and the second resist layer 14, respectively. It should be noted that the obtained resist patterns are formed as parallel linear shapes.

[0218] Next, for the metal-clad laminate 24, using a spraying device with two fluids nozzles (hybrid etching device (trade name) manufactured by Tokyo Kakoki Co., Ltd.), the gaps (S) and (s) between the respective metal wirings of the first metal foil 11 and the second metal foil 12 are each 15 μm (design value), the ratio of the gap (S) between the metal wirings to any thickness (D b ) of the first metal foil 11 is (S / D b ) = 1.36 (design value), and thus is 1.6 or less, the ratio of the gap (s) between the metal wirings to any thickness (d b ) of the second metal foil 12 is (s / d b ) = 1.36 (design value), and thus is 1.6 or less, the length (L) of the metal wiring in the first metal foil 11 is 1000 μm, the length (l) of the metal wiring in the second metal foil 12 is 1000 μm, the width (W b ) of the metal wiring is exactly the same as the gap (S) between the metal wirings ((W b ) = (S)), the width (w b ) of the metal wiring is exactly the same as the gap (s) between the metal wirings ((w b ) = (s)). In this manner, at an etching solution flow rate of 2.0 L / minute and an air flow rate of 200 L / minute, an etching solution of copper chloride aqueous solution (a mixed solution of copper concentration of 120 - 180 g / L and hydrochloric acid concentration of 100 - 150 g / L) is sprayed for 26 seconds at an etching rate of 0.7 μm / second to etch the first metal foil 11 and the second metal foil 12 of the portions where the resist patterns are not formed, respectively. Next, the first resist layer 13 and the second resist layer 14 are peeled off and removed using a 3% aqueous potassium hydroxide solution to obtain a metal-clad laminate C.

[0219] In the obtained metal foil-clad laminate C, the metal parts of the metal wiring of the first metal foil 11 and the second metal foil 12 are etched in a manner extending from the surface of the metal foil toward the end of the insulating resin layer, resulting in so-called "sagging", making it difficult to form fine wiring with uniform gaps between the metal wirings. In addition, due to the occurrence of "sagging", the wiring is short-circuited near the insulating resin layer.

[0220] [Comparative Example 4]

[0221] In Comparative Example 2, the wiring short-circuited near the insulating resin layer, so the etching time by the copper chloride aqueous solution and the air was extended. That is, the etching solution of the copper chloride aqueous solution (a mixed solution of a copper concentration of 120 to 180 g / L and a hydrochloric acid concentration of 100 to 150 g / L) was sprayed for 36 seconds at an etching rate of 0.7 μm / second at an etching rate of 2.0 L / min and 200 L / min of the etching solution, and the first metal foil 11 and the second metal foil 12 where the resist pattern was not formed were etched respectively. Then, the first resist layer 13 and the second resist layer 14 were peeled off and removed with a 3% potassium hydroxide aqueous solution, and a metal foil-clad laminate D was obtained.

[0222] The obtained metal foil-clad laminate D was measured. As a result, the thickness (D) of the metal wiring on the surface of the first metal foil 11 was 11 μm (thickness variation: 20%), and the average thickness (D) of the metal wiring was 11 μm. ave ) is 11μm, the gap between metal wirings (U) is 20±3μm, and the average gap between metal wirings (U ave ) is 20μm, the width of the metal wiring (W) is 10±3μm, and the average width of the metal wiring (W ave ) is 10 μm, the ratio (U / D) of the gap between metal wirings (U) to the thickness of metal wirings (D) is 1.28, and the average gap between metal wirings (U ave ) and the average thickness of metal wiring (D ave ) ratio (U ave / D ave ) is 1.81, the ratio of the width (W) of the metal wiring to the thickness (D) of the metal wiring (W / D) is 0.53, and the average width (W) of the metal wiring is ave ) and the average thickness of metal wiring (D ave ) ratio (W ave / D ave ) is 0.91. On the surface of the second metal foil 12, the thickness (d) of the metal wiring is 11 μm (thickness variation: 20%), and the average thickness (d) of the metal wiring is ave ) is 11μm, the gap between metal wirings (u) is 20±3μm, and the average gap between metal wirings (u ave) is 20 μm, the width (w) of the metal wiring is 10 ± 3 μm, and the average width (w ave ) is 10 μm, the ratio (u / d) of the gap (u) between the metal wirings to the thickness (d) of the metal wiring is 1.28, and the average gap (u ave ) between the metal wirings and the average thickness (d ave ) of the metal wiring, the ratio (u ave / d ave ) is 1.81, the ratio (w / d) of the width (w) of the metal wiring to the thickness (d) of the metal wiring is 0.53, and the average width (w ave ) of the metal wiring and the average thickness (d ave ) of the metal wiring, the ratio (w ave / d ave ) is 0.91. In addition, the gap (U) between the metal wirings is 20 ± 3 μm, and the gap (u) between the metal wirings is 20 ± 3 μm. Therefore, the average values of the gaps (U) and (u) are 53% with respect to the design value (15 μm). Therefore, there is a defect in the gap between the metal wirings.

[0223] In addition, in the obtained metal foil-clad laminate, the minimum value of the width of the metal wiring becomes 9 μm. When the wiring width becomes narrow, the transmission loss of the electrical signal increases, and the risk of open circuit also increases.

[0224] This application is based on Japanese Patent Application No. 2019-88770 filed on May 9, 2019, the content of which is incorporated herein by reference.

[0225] Industrial Applicability

[0226] According to the present invention, a printed circuit board having a uniform gap between metal wirings and fine wirings can be manufactured with high productivity. In addition, according to the present invention, a printed circuit board having a uniform gap between metal wirings and fine wirings can be provided.

[0227] Explanation of Reference Numerals

[0228] 10... Insulating resin layer, 11... First metal foil, 12... Second metal foil, 13... First resist layer, 14... Second resist layer, 21... Metal foil-clad laminate, 22... Metal foil-clad laminate subjected to opening and plating processes, 23... Metal foil-clad laminate formed with the first resist layer and the second resist layer, 24... Metal foil-clad laminate formed with a resist pattern, 25... Metal foil-clad laminate formed with metal wirings, 26... Metal foil-clad laminate from which the first resist layer and the second resist layer have been removed, 31... Spray for spraying a developing solution, 32... Spray for spraying an etching solution, 41... Gap (R) between resist patterns, 42... Gap (S) between metal wirings, 43... Arbitrary thickness (D) of the metal foilb and D), 44... the width (W b and W).

Claims

1. A manufacturing method of a printed circuit board, comprising the following processes: Process for preparing a metal foil-clad laminate, the metal foil-clad laminate having a metal foil and an insulating resin layer laminated thereon, the metal foil having an arbitrary thickness D in the range of 3 to 20 μm b ; A process of forming a resist layer on the surface of the metal foil; A process of exposing and developing the resist layer to form a resist pattern; A process of etching the metal foil of the portion where the resist pattern is not formed by spraying air together with an etching solution using a spray having two fluid nozzles to form a metal wiring; And, A process of removing the resist layer, In the process of forming the metal wiring, the spraying is performed at an etching rate of 0.05 to 1.5 μm / second for a spraying time of 20 to 120 seconds. The flow rate of the etching solution in the two fluid nozzles is 0.5 to 3.5 L / minute, and the flow rate of air is 100 to 400 L / minute. The gap S between the metal wirings includes 15 to 50 μm, and the ratio S / D of the gap S between the metal wirings to any thickness D of the metal foil b is b formed in such a manner that it exceeds 1.6 for the metal wiring.

2. The manufacturing method of the printed circuit board according to claim 1, wherein, The etching solution is an aqueous copper chloride solution which is a mixed solution with a copper concentration of 120 to 180 g / L and a hydrochloric acid concentration of 100 to 150 g / L.

3. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, In the process of forming the resist pattern, the gap R between the resist patterns is formed in such a manner that it is 1 to 5 μm narrower than the gap S between the metal wirings.

4. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, The printed circuit board continuously has at least a gap US2 formed in the gap U between the metal wirings formed on the metal foil and having the same width as the gap S between the metal wirings.

5. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, In the step of forming the metal wiring, with the width W of the metal wiring b being equal to the gap S between the metal wirings, that is, W b = S, the formation is carried out in this manner.

6. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, In the process of preparing the metal foil-clad laminate, the metal foil has its thickness adjusted to any thickness D within the range of 3 to 20 μm. b The obtained metal foil.

7. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, The thickness of the resist layer formed on the surface of the metal foil is 15 μm or less.

8. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, In the process of forming the metal wiring, it is formed in such a manner that the length L of the metal wiring is 100 μm or more.

9. The manufacturing method of the printed circuit board according to claim 1 or 2, wherein, The metal foil is a copper foil.

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