Methods for manufacturing circuit boards and circuit boards

Abstract

This invention discloses a method for manufacturing a circuit board, comprising: a step of pretreating the surface of a metal layer exposed in an opening by contacting it with a pretreatment solution at a specific pretreatment temperature; and a step of forming a copper plating layer on the metal layer by electroplating. The resist layer and the pretreatment solution are selected such that the mass change rate of the resist layer when immersed in the pretreatment solution before exposure and development is -2.0% by mass or more. The mass change rate is calculated using the formula: Mass Change Rate (mass%) = {(W1-W0) / W0} × 100. W1 is the mass of the resist layer after immersing the laminate having the resist layer 3 and copper foil in the pretreatment solution at the pretreatment temperature for 30 minutes.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a circuit board and the circuit board itself. [Previous Technology]

[0002] In order to meet the requirements of miniaturization, lightweighting, and high speed of electronic devices, the circuit boards constituting the electronic devices need to have wiring with minute widths. As a method for forming wiring with minute widths, the semi-additive process (SAP) and the modified semi-additive process (MSAP) are widely used (Patent Document 1). These methods generally include the step of forming a copper plating layer on a metal layer by electroplating.

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2004-6773

[0004] When a copper plating layer is formed on a metal layer serving as a seed layer by electroplating, tiny black portions with a width of less than 0.3 μm are sometimes observed in the copper plating layer near the interface between the metal layer and the copper plating layer. These black portions are estimated to be tiny voids. Since these black portions are extremely small voids, they are unlikely to affect the characteristics of the wiring itself. However, as the wiring width is further miniaturized, if there are many tiny voids, the adhesion between the copper plating layer and the metal layer may be insufficient. [Summary of the Invention]

[0005] One aspect of the present invention relates to a method for manufacturing a circuit board by means of a step including forming a copper plating layer on a metal layer by electroplating, thereby suppressing the formation of minute black portions near the interface between the metal layer and the copper plating layer.

[0006] One aspect of the present invention relates to a method for manufacturing a circuit board, the method comprising the steps of: forming a resist layer on a metal layer disposed on a support; forming a pattern including openings for exposing the metal layer on the resist layer by exposure and development of the resist layer; pretreating the surface of the metal layer exposed in the openings by contacting it with a pretreatment solution at a specific pretreatment temperature; and forming a copper plating layer on the metal layer by electroplating. The resist layer and the pretreatment solution are selected such that the mass change rate of the resist layer when immersed in the pretreatment solution before exposure and development is -2.0% by mass or more. The aforementioned rate of change in mass is calculated using the following formula: Rate of change in mass (mass%) = {(W1-W0) / W0} × 100. W0 is the mass of the resist layer before immersion in the aforementioned pretreatment solution, and W1 is the mass of the resist layer after immersing the laminate containing the resist layer and a single-sided copper foil covering the resist layer in the aforementioned pretreatment solution at the aforementioned pretreatment temperature for 30 minutes. [Effects of the Invention]

[0007] According to one aspect of the present invention, a method is provided in which, when manufacturing a circuit board using a method including the step of forming a copper plating layer on a metal layer by electroplating, the generation of tiny black portions near the interface between the metal layer and the copper plating layer is suppressed.

Implementation Method

[0009] The present invention is not limited to the following examples.

[0010] FIG1 is a cross-sectional view showing an example of a method for manufacturing a circuit board. The method shown in FIG1 includes the following steps in sequence: forming a metal layer 20 on one main surface of a plate-shaped support 1; forming a resist layer 3 on the metal layer 20; forming a pattern including an opening 3A for exposing the metal layer 20 on the resist layer 3 by exposure and development of the resist layer 3; performing a pretreatment on the surface of the metal layer 20 exposed in the opening 3A by contacting it with a pretreatment solution at a specific pretreatment temperature; forming a copper plating layer 21 on the metal layer 20 by electroplating; removing the resist layer 3 to expose the portion of the metal layer 20 not covered by the copper plating layer 21; and removing the exposed portion of the metal layer 20 to form a circuit board 10 having wiring 2 and a support 1 having the metal layer 20 and the copper plating layer 21.

[0011] The outermost layer of the side of the support 1 where the metal layer 20 is disposed is generally mainly composed of an insulating layer. The insulating layer disposed as the outermost layer of the support 1 can be, for example, an insulating resin layer such as an added layer. The support 1 may include wiring connected to the wiring 2. The support 1 may include a laminated board, i.e., an insulating substrate, formed by a plurality of prepregs.

[0012] The metal layer 20 functions as a seed layer for electroplating. The metal layer 20 can be, for example, a metal electroplating layer formed without electroplating, a metal foil such as copper foil, a layer formed by vapor deposition such as sputtering, or a sintered metal layer. A sintered metal layer is formed by heating a coating containing metal particles to sinter the metal particles. The metal constituting the metal layer 20 can include, for example, at least one metal selected from the group consisting of copper, gold, silver, tungsten, molybdenum, tin, cobalt, chromium, iron, and zinc. The metal layer 20 can be a single layer or composed of two or more layers. The thickness of the metal layer 20 can be, for example, 0.1 to 2.0 μm.

[0013] The arithmetic surface roughness Ra of the surface of the metal layer 20 opposite to the support 1 can be 0.20 to 0.30 μm. The average height Rc of the surface of the metal layer 20 opposite to the support 1 can be 0.7 to 1.3 μm. If the arithmetic surface roughness Ra and / or the average height Rc are within this range, it is easier to obtain better results from the viewpoint of reducing the black portion in the copper plating.

[0014] Regarding the resist layer 3, it can be formed from a photosensitive resist material typically used to form wiring, selected based on the rate of mass change caused by impregnation in the pretreatment solution as described below. The thickness of the resist layer 3 can be, for example, 10 to 50 μm.

[0015] The resist material used to form the resist layer 3 may be, for example, a photosensitive resin composition comprising an adhesive polymer, a photopolymerizable compound having ethylene unsaturated bonds, and a photopolymerization initiator.

[0016] The adhesive polymer may be, for example, a copolymer comprising benzyl (meth)acrylate or a derivative thereof, styrene or a styrene derivative, alkyl (meth)acrylate and (meth)acrylic acid as monomer units.

[0017] Specific examples of benzyl acrylate derivatives constituting adhesive polymers include 4-methylbenzyl acrylate, 4-ethylbenzyl acrylate, 4-tert-butylbenzyl acrylate, 4-methoxybenzyl acrylate, 4-ethoxybenzyl acrylate, 4-hydroxybenzyl acrylate and 4-chlorobenzyl acrylate.

[0018] Specific examples of styrene derivatives constituting adhesive polymers include vinyltoluene, p-methylstyrene, and p-chlorostyrene.

[0019] The alkyl (meth)acrylate constituting the adhesive polymer can be an ester compound formed from (meth)acrylic acid and a linear or branched aliphatic alcohol having 1 to 12 carbon atoms. The aliphatic alcohol may have 1 to 8 or 1 to 4 carbon atoms. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, tributyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0020] The proportion of monomer units derived from benzyl (meth)acrylate or its derivatives in the adhesive polymer, based on the mass of the adhesive polymer, can be 50-80% by mass, 50-75% by mass, 50-70% by mass, or 50-65% by mass. The proportion of monomer units derived from styrene or styrene derivatives in the adhesive polymer, based on the mass of the adhesive polymer, can be 5-40% by mass or 5-35% by mass. The proportion of monomer units derived from alkyl (meth)acrylate in the adhesive polymer, based on the mass of the adhesive polymer, can be 1-20% by mass, 1-15% by mass, 1-10% by mass, or 1-5% by mass. The proportion of monomer units derived from (meth)acrylic acid in the adhesive polymer, based on the mass of the adhesive polymer, can be 5-30% by mass, 5-25% by mass, or 10-25% by mass.

[0021] The weight-average molecular weight (Mw) of the adhesive polymer can be 20,000–150,000, 30,000–100,000, 40,000–80,000, or 40,000–60,000. The weight-average molecular weight mentioned herein represents the standard polystyrene conversion value obtained by gel permeation chromatography (GPC).

[0022] The acid value (mgKOH / g) of the adhesive polymer can be 13-78, 39-65, or 52-62. The acid value described herein represents the amount (mg) of potassium hydroxide required to neutralize 1g of adhesive polymer.

[0023] Specific examples of photopolymerizable compounds having ethylene-like unsaturated bonds include bisphenol A-based (meth)acrylate compounds, hydrogenated bisphenol A-based (meth)acrylate compounds, polyalkylene glycol (meth)acrylates, amine ester monomers, neopentyl terephthalol (meth)acrylates, and trimethylolpropane (meth)acrylates. These can be used alone or in combination of two or more. For example, a bisphenol A-based di(meth)acrylate compound can be a compound represented by the following general formula (1).

[0024]

Chemical Formula 1

[0025] In formula (1), R independently represents a hydrogen atom or a methyl group. EO and PO represent oxyethylene and oxypropylene groups, respectively. m1, m2, n1, and n2 independently represent 0 to 40, m1+m2 is 1 to 40, and n1+n2 is 0 to 20. Either EO or PO can be on the phenolic hydroxyl side. m1, m2, n1, and n2 represent the amount of EO or PO, respectively. Compounds with an average m1+m2 of less than 5 and compounds with an average m1+m2 of 6 to 40 can be combined.

[0026] Polyalkyl diol (meth)acrylate can be a compound represented by the following formula (2). As a photopolymerizable compound having vinyl unsaturated bonds, a combination of bisphenol A di(meth)acrylate compounds and a compound represented by the following formula (2) can be used.

[0027]

Chemical Formula 2

[0028] In formula (2), R14 and R15 independently represent hydrogen atoms or methyl groups, EO and PO have the same meaning as above, s1 represents 1 to 30, r1 and r2 represent 0 to 30, and r1+r2 is 1 to 30. As an example of a commercially available product of the compound represented by formula (2), a vinyl compound with R14 and R15 being methyl, r1+r2=4 (average), and s1=12 (average) can be cited (manufactured by Showa Denko Materials Co., Ltd., product name: FA-023M).

[0029] Specific examples of photopolymerization initiators include benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone (milchnerone), N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-acetone-1, etc.; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, 2-methyl-1 Quinones such as 4-naphthoquinone and 2,3-dimethylanthraquinone; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin, and ethyl benzoin; benzyl derivatives such as benzyl dimethyl ketal; 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer; 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazolium dimer; 2-(o-fluorophenyl) 2,4,5-triarylimidazolium dimers, such as 2-(o-methoxyphenyl)-4,5-diphenylimidazolium dimer and 2-(p-methoxyphenyl)-4,5-diphenylimidazolium dimer; acridine derivatives such as 9-phenylacridinium and 1,7-bis(9,9'-acridyl)heptane; N-phenylglycine; N-phenylglycine derivatives; and coumarin compounds. These can be used alone or in combination of two or more types. Photopolymerization initiators may contain 2,4,5-triarylimidazolium dimers, and particularly may contain 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer.

[0030] The content of the binder polymer in the photosensitive resin composition, relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound, may be 40-80 parts by mass, 45-75 parts by mass, or 50-70 parts by mass. The content of the photopolymerization initiator in the photosensitive resin composition, relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound, may be 0.01-5 parts by mass, 0.1-4.5 parts by mass, or 1-4 parts by mass.

[0031] The photosensitive resin composition may contain other components as needed. Examples of other components include photopolymerizable compounds having cyclic ether groups capable of polymerizing cationic groups, cationic polymerization initiators, sensitizers, dyes such as malachite green, photochromic agents such as tribromomethylphenyl sulfone and leuco crystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, defoamers, flame retardants, stabilizers, adhesion promoters, leveling agents, peel accelerators, antioxidants, fragrances, developers, and thermocrosslinking agents. The content of other components may be approximately 0.01 to 20 parts by mass relative to the total mass of the adhesive polymer and the photopolymerizable compound per 100 parts by mass.

[0032] The total content of the binder polymer, photopolymerizable compound and photopolymerization initiator in the photosensitive resin composition relative to the total mass of the components other than the solvent in the photosensitive resin composition can be 90-100% by mass or 95-100% by mass.

[0033] In order to form the resist layer 3, a resist film containing a photosensitive resin composition can be deposited on the metal layer 20, or a photosensitive resin composition containing a solvent can be coated on the metal layer 20 and the solvent can be removed from the coating.

[0034] By exposing a portion of the resist layer 3 and developing the exposed resist layer 3, a resist layer 3 having a pattern including openings 3A is formed. The exposure and development can be performed using conventional methods known to those skilled in the art. A fine pattern including openings 3A for exposing the metal layer 20 is formed by exposure via a photomask. The developing solution used can be an alkaline aqueous solution such as an aqueous sodium carbonate solution.

[0035] Next, the surface of the metal layer 20 exposed within the opening 3A is pretreated by contacting it with a pretreatment solution at a specific pretreatment temperature. For example, the surface of the metal layer 20 can be pretreated by immersing the intermediate structure comprising the support 1, the metal layer 20, and the patterned resist layer 3 in a pretreatment solution adjusted to a specific pretreatment temperature. The pretreatment temperature can be appropriately set depending on the type of pretreatment solution, but it can be in the range of 20 to 50°C, for example. The immersion time in the pretreatment solution can be, for example, 1 to 8 minutes.

[0036] Regarding the pretreatment solution, it can be selected from those commonly used for electroplating based on the mass change rate of immersion in the pretreatment solution based on the resist layer 3, as described later. The pretreatment solution can be acidic or may contain alcohol. The alcohol content, based on the mass of the pretreatment solution, can be 0.2 to 5% by mass.

[0037] The pretreatment solution may be, for example, an acidic aqueous solution containing acid components, electroplating additives, and reducing agents.

[0038] The acid component can be an organic acid, an inorganic acid, or a combination thereof. Specific examples include sulfuric acid; alkyl sulfonic acids such as methanesulfonic acid and propanesulfonic acid; alkyl alcohol sulfonic acids such as hydroxyethanesulfonic acid and propanol sulfonic acid; and carboxylic acids such as citric acid, tartaric acid, and formic acid. One of these can be used alone or in combination of two or more. The concentration of the acid component in the pretreatment solution, based on the volume of the pretreatment solution, can be 10–300 g / L or 50–200 g / L.

[0039] Electroplating additives may be, for example, polyether compounds, organosulfur compounds, or combinations thereof. Examples of polyether compounds include polyethylene glycol, polypropylene glycol, and their derivatives. Organosulfur compounds are copper plating precipitation promoters sometimes called brighteners; examples include 3-mercaptopropanesulfonic acid and disodium bis(3-sulfopropyl)disulfide. The concentration of the additive in the pretreatment solution, based on the volume of the pretreatment solution, may be 0.1 to 10000 mg / L.

[0040] Examples of reducing agents include hypophosphite, phosphite, dimethylamine borane, trimethylamine borane, hydrazine derivatives, boron hydride salts, aldehyde compounds (e.g., formalin, glyoxylic acid), titanium trichloride, catechol, resorcinol, hydroquinone, ascorbate, phenylenediamine, and hypophosphinolic acid derivatives. One of these can be used alone or in combination of two or more. The concentration of the reducing agent in the pretreatment solution, based on the volume of the pretreatment solution, can be 0.0001 to 0.1 mol / L.

[0041] The pretreatment solution may further contain a surfactant selected from alkylbenzene sulfonates and compounds having an acetylene group. The pretreatment solution may contain carboxylic acids or alkylsulfonic acids, inorganic acids selected from hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, alkylbenzene sulfonates and compounds having an acetylene group. In this case, the content of carboxylic acids and alkylsulfonic acids may be 5-50 g / L or 10-20 g / L based on the volume of the pretreatment solution, and the content of inorganic acids may be 1-20 g / L or 2-10 g / L based on the volume of the pretreatment solution.

[0042] Alkylbenzene sulfonates are salts of sulfonic acid compounds having a benzene ring and an alkyl group bonded to the benzene ring and a sulfonic acid group. The alkyl group may have 10 to 16 carbon atoms. Alkylbenzene sulfonates may be sodium salts, potassium salts, or triethanolamine salts. As a specific example of an alkylbenzene sulfonate, linear sodium dodecylbenzene sulfonate can be given. The content of alkylbenzene sulfonate, based on the volume of the pretreatment solution, may be 0.5 to 20 g / L.

[0043] Examples of commercially available surfactants containing acetylene groups include Surfynol 104, Surfynol 440, and Surfynol 465 (product names, manufactured by Nissin Chemical Industry Co., Ltd.). The content of the acetylene-containing compound can be 0.1–5 g / L or 0.3–1 g / L, based on the volume of the pretreatment solution.

[0044] The pretreatment solution may contain a dispersant. The dispersant may be a polymer containing monomer units derived from maleic acid. As an example of a commercially available product, MALIALIM AKM-0531 (product name, manufactured by NOF CORPORATION) may be used. The content of the dispersant may be 0.1 to 5 g / L or 0.3 to 1 g / L, based on the volume of the pretreatment solution.

[0045] The resist layer 3 and the pretreatment solution are selected such that the mass change rate of the resist layer 3 when it is immersed in the pretreatment solution before exposure and development is -2.0% by mass or more. The mass change rate is calculated using the following formula: Mass change rate (mass%) = {(W1-W0) / W0} × 100. W0 is the mass of the resist layer 3 before immersion in the pretreatment solution, and W1 is the mass of the resist layer 3 after immersing the laminate containing the resist layer 3 and a single-sided copper foil covering the resist layer 3 in the pretreatment solution at the pretreatment temperature for 30 minutes. This mass change rate reflects the balance between the amount of components dissolved from the resist layer 3 into the pretreatment solution and the amount of pretreatment solution absorbed by the resist layer 3 during the immersion of the resist layer 3 in the pretreatment solution. According to the inventors, when the resist layer 3 and the pretreatment solution have a mass change rate of -2.0% by mass or more, the formation of fine black particles in the copper plating layer 22 can be significantly suppressed. From the same perspective, the mass change rate can be -1.0% by mass or more, or -0.5% by mass or more. From the viewpoint of suppressing the peeling of the wiring 2, the mass change rate can be 3.0% by mass or less. The resist layer 3 and the pretreatment solution can be selected by considering the solubility of each component constituting the resist layer 3 in the pretreatment solution, so that the mass change rate is within a specific range.

[0046] A copper plating layer 21 filling the opening 3A is formed on the surface of the pretreated metal layer 20 by electroplating. Then, the resist layer 3 is peeled off from the metal layer 20. The portion of the metal layer 20 exposed by the peeling off of the resist layer 3 is removed using conventional methods such as etching. As a result, a wiring 2 consisting of the metal layer 20 remaining on the support 1 and the electroplated metal layer 21 is formed.

[0047] The electroplated layer 21 and the wiring 2 may include linear portions with a width of 5 to 20 μm. In other words, the line / space (L / S) of the wiring 2 may be 5 μm / 5 μm to 20 μm / 20 μm. According to the method of the present invention, even with such fine wiring, defects such as wire peeling and detachment are hardly produced.

[0048] The circuit board 10 manufactured by the above steps includes: a support 1; and wiring 2, having a metal layer 20 disposed on the support 1 and a copper plating layer 21 formed on the metal layer 20. The number of black portions observed in the copper plating layer 21 can be 8 or less per 1μm of width parallel to the main surface of the support 1 of the wiring 2. The number of black portions mentioned here refers to the number of black portions with a maximum width of less than 0.3μm observed by a scanning electron microscope. [Example]

[0049] The present invention is not limited to the following embodiments.

[0050] 1. Material pretreatment solution is prepared as a pretreatment solution for pretreating the seed layer before electroplating, comprising acidic pretreatment solution A (alcohol content: 0.7% by mass) and pretreatment solution B (alcohol content: 0.6% by mass) and pure water.

[0051] Photosensitive resist film A and resist film B (both manufactured by Showa Denko Materials Co., Ltd.) for circuit formation were prepared. The thickness of these photosensitive resist films is 25 μm.

[0052] Changes in the mass of the resist film caused by immersion in the pretreatment solution: Copper-clad laminates for printed circuit boards (CCLs) with a cross-section of 50 mm and a thickness of 0.45 mm were prepared, and the mass of each CCL was measured. Using a laminator (LAMI CORPORATION INC., GK-13DX), resist film A or resist film B was laminated onto both sides of each CCL, thus forming a laminate of copper foil including the resist film and a single-sided integral copper-clad laminate covering the resist film. The lamination temperature was 110°C, the lamination speed was 1.4 m / min, and the lamination pressure was 0.5 MPa. The total mass of the CCL and the resist film was measured. The initial mass W0 of the resist film (resistor layer) was determined by subtracting the mass of each CCL from the measured mass.

[0053] Next, the copper-clad laminate with the resist film laminated is immersed in pretreatment solution A at 40°C, pretreatment solution B at 45°C, or pure water at 25°C for 30 minutes. The immersed copper-clad laminate and resist film are dried by heating in an oven at 70°C for 30 minutes. The total mass of the dried copper-clad laminate and resist film is measured. The mass W1 of the resist film (resistor layer) immersed in the pretreatment solution is obtained by subtracting the mass of each copper-clad laminate from the measured mass after drying. The mass change rate (%) of the resist film (resistor layer) caused by immersion in the pretreatment solution is calculated by the following formula: Mass change rate (%) = {(W1-W0) / W0} × 100

[0054] 2. The wiring is formed using the combination of resist film and pretreatment solution shown in Table 1, and the wiring is formed according to the following steps.

[0055] For the formation of the insulating resin layer, a 50mm square copper-clad laminate for printed circuit boards (Showa Denko Materials Co., Ltd.) with a thickness of 0.45mm and an insulating material for forming the insulating resin layer (Ajinomoto Build-up Film GX-92, manufactured by Ajinomoto Fine-Techno Co., Inc.) was prepared. The insulating material has a support film, an insulating curable resin film disposed on the support film, and a protective film. The protective film is peeled off from the insulating material, and the exposed curable resin film is placed on the copper-clad laminate. The placed curable resin film is pressed onto the copper-clad laminate using a pressure-type vacuum laminator (MVLP-500, manufactured by meiki co., ltd.). The pressing conditions are: hot plate temperature of 80°C, vacuum time of 20 seconds, pressing time of 60 seconds, air pressure of 4 kPa or less, and pressure of 0.4 MPa. Subsequently, the curable resin film was cured by heating at 180°C for 30 minutes and then at 190°C for 60 minutes in an oven, thereby forming an insulating resin layer on the copper foil of the copper-clad laminate.

[0056] Next, the laminate formed by the insulating resin layer and the copper-clad laminate is sequentially immersed in a mixed aqueous solution of 500 mL / L Swelling Dip Securigant (manufactured by Atotech Japan) and 3 g / L NaOH at 80°C for 15 minutes, immersed in pure water at room temperature for 2 minutes, immersed in a mixed aqueous solution of 640 mL / L Compact CP (manufactured by Atotech Japan) and 40 g / L NaOH at 80°C for 20 minutes, immersed in pure water at 50°C for 2 minutes, immersed in a mixed aqueous solution of 100 mL / L Reduction Securigant (manufactured by Atotech Japan) and 50 mL / L 98% sulfuric acid at 40°C for 5 minutes, and immersed in pure water at room temperature for 1 minute. The surface of the insulating resin layer is roughened by immersion in the descaling solution.

[0057] The seed layer is formed by sequentially immersing the laminate formed from the roughened insulating resin layer and the copper-clad laminate in a 50 mL / L aqueous solution of an acidic pretreatment reagent for electroless plating (manufactured by C. Uyemura & Co., Ltd., product name: MCD-PL) at 40°C for 5 minutes, immersing in pure water at 40°C for 1 minute, immersing in pure water at room temperature for 1 minute, immersing in a 10% sulfuric acid aqueous solution at room temperature for 1 minute, immersing in pure water at room temperature for 1 minute, and then in a pre-dip reagent (C. Uyemura & Co. The following solutions were prepared: MDP-2 (manufactured by C. Uyemura & Co., Ltd., product name: MDP-2) and sulfuric acid (MDP-2 concentration: 10 mL / L, 95% sulfuric acid: 1 mL / L) for 2 minutes at room temperature; MAT-SP (mAT-SP concentration: 50 mL / L, NaOH: 1.6 g / L) for 5 minutes at 40°C; MAT-SP (manufactured by C. Uyemura & Co., Ltd., product name: MAT-SP) and NaOH (MAT-SP concentration: 50 mL / L, NaOH: 1.6 g / L) for 1 minute in pure water at room temperature; and MAT-SP (mAT-SP) for 1 minute in reducing agent (C. Uyemura & Co., Ltd., product name: MAT-SP) and NaOH (MAT-SP concentration: 50 mL / L, NaOH: 1.6 g / L) for 1 minute in pure water at room temperature; and MAT-SP (mAT-SP) for 1 minute in reducing agent (MAT-SP) and NaOH (MAT-SP concentration: 10 mL / L, 95% sulfuric acid: 1 mL / L). The reagents were immersed in a mixture of MRD-2-C, MAB-4-C, and MAB-4-A (Made by Uyemura & Co., Ltd., product name: MRD-2-C, MAB-4-C, MAB-4-A) at 35°C for 3 minutes, immersed in pure water for 1 minute, immersed in a 50 mL / L aqueous solution of an accelerator reagent (Made by C. Uyemura & Co., Ltd., product name: MEL-3A) at room temperature for 1 minute, and immersed in an electroless plating reagent (C. Uyemura & Co., Ltd., product name: MEL-3A) at 35°C for 3 minutes, immersed in pure water for 1 minute, immersed in an aqueous solution of an accelerator reagent (Made by C. Uyemura & Co., Ltd., product name: MEL-3A) at 30°C for 1 minute, and immersed in an electroless plating reagent (C. Uyemura & Co., Ltd., product name: MEL-4-A) for 1 minute. Uyemura&Co.,Ltd. (products: PEA-6A, PEA-6-B-2X, PEA-6-C, PEA-6-D, PTA-6-E) were immersed in a mixture of formaldehyde (PEA-6A concentration: 100 mL / L, PEA-6-B-2X concentration: 50 mL / L, PEA-6-C concentration: 14 mL / L, PEA-6-D concentration: 15 mL / L, PEA-6-E concentration: 50 mL / L, formaldehyde concentration: 5 mL / L) at 36°C for 15 minutes, followed by immersion in pure water for 1 minute. A metal layer was formed as a seed layer by electroless plating, including these immersion treatments. The formed seed layer was annealed by heating in an oven at 150°C for 30 minutes. In Example 2, the seed layer was formed by depositing copper foil on an insulating resin layer. The arithmetic surface roughness Ra and average height Rc of the seed layer on the opposite side of the insulating resin layer were measured using laser microscopy (JIS B 0601:2013 (ISO 4287:1997, Amd.1:2009)).

[0058] The resist layer was formed using a laminator (LAMI CORPORATION INC., GK-13DX) to laminate resist film A or resist film B onto the seed layer. The lamination temperature was 110°C, the lamination speed was 1.4 m / min, and the lamination pressure was 0.5 MPa. After lamination, the film was left to stand for 30 minutes, and then exposed using a photolithography machine (Mikasa Corporation, ML-320FSAT), a bandpass filter (Asahi Spectra Co., Ltd., HB0405), and a negative photomask. The exposure dose was 45 mJ / cm². After exposure, the film was left to stand for 30 minutes, the protective film of the resist film was peeled off, and the film was developed using a 1.0% sodium carbonate aqueous solution, thereby forming a patterned resist layer with linear openings of 10 μm width for exposing the seed layer. For development, an ultra-high pressure rotary developing device (manufactured by Blue Ocean Technology, Ltd.) was used, in which the developer was sprayed for 100 seconds, followed by the rinsing solution of pure water for 100 seconds. The developing temperature was 30°C, the rotation speed was 500 rpm, the spray pressure was 0.18 MPa, the travel distance of the spray nozzle was 7.2 cm, and the travel speed of the spray nozzle was 10 cm / s.

[0059] The pretreatment involves immersing the laminate formed by the seed layer, resist layer, and copper-clad laminate in pretreatment solution A at 40°C, pretreatment solution B at 45°C, or pure water at room temperature (25°C). Then, the laminate is sequentially immersed in pure water at 50°C for 1 minute, in pure water at 25°C for 1 minute, and in a 10% sulfuric acid aqueous solution at 25°C for 1 minute.

[0060] Electroplating: The pretreated laminate was immersed in an electroplating solution and electroplated on a seed layer at 25°C and a current density of 10 A / dm² for 10 minutes. Then, the laminate with wiring having both a seed layer and a copper plating layer was immersed in pure water at room temperature for 1 minute. The electroplating solution used was a mixture of 7.3 L of an aqueous solution containing 120 g / L copper sulfate decahydrate, 220 g / L 96% sulfuric acid, 0.25 mL hydrochloric acid, 92 mL Top Lucina NSV-1 (product name, manufactured by OKUNO CHEMICAL INDUSTRIES CO.,LTD.), 11.5 mL Top Lucina NSV-2 (product name, manufactured by OKUNO CHEMICAL INDUSTRIES CO.,LTD.), and 23 mL Top Lucina NSV-3 (product name, manufactured by OKUNO CHEMICAL INDUSTRIES CO.,LTD.).

[0061] 3. Evaluation of the black portion: The formed wiring was processed using a focused ion beam apparatus (Hitachi High-Tech Corporation, MI4050) to create a test piece with a cross-section near the interface between the seed layer and the electroplated layer. Eight locations near the interface between the seed layer and the electroplated layer in the cross-section of the test piece were photographed at 50,000x magnification using a scanning electron microscope (Hitachi High-Tech Corporation, SU8200). The obtained cross-sectional images were binarized to make only the tiny black portions existing between the electroless and electrolytic copper plating layers black, and the number of black portions was recorded. Figure 2 shows an example of a binarized electron microscope image. The number of black portions per 1 μm width in the interface direction was calculated. ImageJ image editing software was used for binarization. Table 1 shows the average number of black portions at the eight observation locations.

[0062] The wiring formation observation confirmed whether any of the 10 wirings were detached or stripped.

[0063]

Table 1

[0064] As shown in Table 1, it was confirmed that by selecting a combination of a pretreatment solution and a resist film in which the mass change rate of the resist film when immersed in the pretreatment solution is -2.0% by mass or more, the generation of black parts near the interface between the seed layer (metal layer) and the electroplated layer can be effectively suppressed. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a cross-sectional view illustrating an example of a method for manufacturing a circuit board. Figure 2 is an example of a binarized electron microscope image of the area near the interface between the metal layer and the copper plating layer.

Claims

1. A method for manufacturing a circuit board, comprising, in sequence: The step of forming a resist layer on a metal layer disposed on a support; The process includes the steps of forming a pattern on the resist layer, including openings for exposing the metal layer, by exposure and development of the resist layer; pre-treating the surface of the metal layer exposed in the openings by contacting it with a pre-treatment solution at a specific pre-treatment temperature; and forming a copper plating layer on the metal layer by electroplating. The resist layer and the pre-treatment solution are selected such that the mass change rate of the resist layer when it is immersed in the pre-treatment solution before exposure and development is -2.0% by mass or more. The mass change rate is a value calculated by the following formula: Mass change rate (mass%) = {(W1-W0) / W0}×100, where W0 is the mass of the resist layer before immersion in the pre-treatment solution, and W1 is the mass of the resist layer after immersing the laminate containing the resist layer and a single copper foil covering the resist layer in the pre-treatment solution at the pre-treatment temperature for 30 minutes.

2. The method as described in claim 1, wherein the aforementioned pretreatment solution is an acidic pretreatment solution.

3. The method as described in claim 1 or claim 2, wherein the aforementioned pretreatment solution comprises alcohol.

4. The method as described in claim 1 or claim 2, wherein the arithmetic surface roughness Ra of the surface of the aforementioned metal layer is 0.20 to 0.30 μm.

5. The method as described in claim 1 or claim 2, wherein the aforementioned electroplated layer includes a linear portion with a width of 5 to 20 μm.

6. The method as described in claim 1 or claim 2, wherein the aforementioned metal layer is a layer disposed on the aforementioned support by electroless plating.

7. A circuit board comprising: a support; and wiring having a metal layer disposed on the support and a copper plating layer formed on the metal layer, wherein the average height Rc of the surface of the copper plating layer side of the metal layer is 0.7 to 1.3 μm, and the number of black portions observed by scanning electron microscopy in the copper plating layer is 8 or less per 1 μm of the wiring width, and the black portions have a width of less than 0.3 μm.

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