JP4349082B2 - Printed wiring board manufacturing method and printed wiring board - Google Patents

Description

  The present invention relates to a printed wiring board manufacturing method and a printed wiring board.

In recent years, there has been an increasing demand for smaller, lighter, and faster electronic devices, and the density of printed wiring boards has been increasing. In recent years, a method for manufacturing printed wiring boards using a semi-additive method using electroplating has attracted attention. ing. In this semi-additive method, for example, as disclosed in Patent Document 1, after forming a hole to be IVH with a laser or the like on the surface of a resin on which a circuit is to be formed, an unevenness of several μm is formed on the resin by chemical roughening or plasma treatment. Then, Pd catalyst is applied, electroless plating of about 1 μm is performed, pattern electroplating resist is formed, circuit formation is performed by pattern electroplating, and then the power supply layer existing in portions other than the resist and the circuit is removed As compared with the subtractive method having a large side etching, finer wiring can be formed. Further, there is a method of forming a circuit on a metal foil with resin by a semi-additive method. In recent years, in order to reduce the thickness of the metal foil, for example, as disclosed in Patent Documents 2 and 3, a peelable type metal foil or etchable in which a metal foil having a thickness of 5 μm or less is formed on a supporting metal foil A type of copper foil is used. In this method, it is not necessary to perform electroless plating on the surface of the insulating resin layer, and a printed wiring board with higher reliability can be manufactured.
JP-A-11-186716 JP-A-13-140090 JP-A-13-89892

  Thus, when circuit formation is performed on a metal foil with a resin by a semi-additive method, the electroless copper plating is excessively etched, and a problem that the conductor circuit shape is impaired is likely to occur. In particular, the portion immediately above the copper foil of electroless copper plating tends to increase the etching rate. Hereinafter, such a phenomenon is referred to as undercut. Use Figure 1 to define the undercut. Here, the code | symbol 1 is electrolytic copper, 2 is electroless copper, 3 is metal foil, 4 shows resin. In FIG. 1, it is desirable that the conductor circuit is rectangular as shown in (a) from the viewpoint of electrical characteristics and the adhesiveness of the conductor circuit. However, when the circuit is actually formed, a dent may be generated around the electroless copper plating portion as shown in (b). This dent of the electroless copper plating part is called undercut. Here, the width difference A between the pattern electrolytic copper plating portion and the electroless copper plating portion is defined as the undercut amount. The undercut is particularly likely to occur when the surface shape of the copper foil is smooth. Here, the causes of undercuts are diverse and difficult to define uniquely. However, the inventors have found that the amount of palladium adsorbed on the metal foil is adjusted in order to prevent the occurrence of undercut as a result of diligent efforts. The present invention provides a method for manufacturing a printed wiring board that suppresses the problem of undercut that causes electroless copper plating to be etched excessively and that has good electrical characteristics.

  The present invention is characterized by the following (1) to (7).

(1) A palladium catalyst was applied on a metal foil fixed on an insulating resin, electroless copper plating was performed, a resist for pattern formation was formed on the electroless copper plating, and a circuit was formed by pattern electroplating. Then, it is a manufacturing method of the printed wiring board which has a process of removing a resist and etching away copper other than a circuit part, Comprising: The adsorption amount on the metal foil of the said metal palladium is 0.05-0.6 microgram / cm < ² > A method for producing a printed wiring board, characterized by being in a range.

(2) The method for producing a printed wiring board according to (1), wherein a chemical solution mainly composed of sulfuric acid / hydrogen peroxide is used in the step of etching away copper other than the circuit portion.

(3) The method for producing a printed wiring board according to (2), wherein the concentration of the sulfuric acid is 5 to 300 g / L, and the concentration of the hydrogen peroxide is 5 to 200 g / L.

(4) The method for producing a printed wiring board according to any one of (1) to (3), wherein the surface roughness (Rz) of the metal foil is 2 μm or less on both sides.

(5) The method for producing a printed wiring board according to any one of (1) to (4), wherein the thickness of the metal foil is 3 μm or less.

(6) The difference between the top width of the conductor circuit and the width of the electroless copper plating immediately above the metal foil, that is, the undercut amount is within 5 μm, Printed wiring board produced by the method.

(7) A hole for interlayer connection is formed on the metal foil fixed on the insulating resin, a palladium catalyst is provided on the metal foil and in the hole for interlayer connection, electroless copper plating is performed, and electroless copper plating is performed. In the method of manufacturing a printed wiring board, the method includes forming a resist for pattern formation on the substrate, forming a circuit by pattern electroplating, removing the resist, and etching away copper other than the circuit portion. A method for producing a printed wiring board, wherein the amount of adsorption onto the metal foil is in the range of 0.05 to 0.6 μg / cm ² .

  As described above, according to the present invention, it is possible to manufacture a printed wiring board that suppresses an undercut defect in which electroless copper plating is excessively etched and has good electrical characteristics.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

  First, a core substrate composed of two types of layers is produced. When producing the core substrate, a method using a laminate having metal foils 6 on both sides of the prepreg 5 as shown in FIG.

  The prepreg is obtained by impregnating or coating a resin composition on a base material, and as the base material, well-known ones used for various laminates for electrical insulating materials can be used.

  Examples of the material of the substrate include inorganic fibers such as E glass, D glass, S glass, and Q glass, organic fibers such as polyimide, polyester, and tetrafluoroethylene, and mixtures thereof. These base materials have shapes such as woven fabric, non-woven fabric, low-ink, chopped strand mat, surfacing mat, etc., and the material and shape are selected depending on the intended use and performance of the molded product, and can be used alone or as required. It can be used from more than a variety of materials and shapes. There is no particular limitation on the thickness of the base material, but usually about 0.03 to 0.5 mm is used, and the surface treated with a silane coupling agent or the like or mechanically opened is heat resistant. From the viewpoint of properties, moisture resistance, and workability.

  As the resin composition, a known and customary resin composition used as an insulating material for a printed wiring board can be used. Usually, thermosetting resin with good heat resistance and chemical resistance is used as the base, and as thermosetting resin, phenol resin, epoxy resin, cyanate resin, maleimide resin, isocyanate resin, benzocyclobutene resin, vinyl resin However, the present invention is not limited to these examples. One type of thermosetting resin may be used alone, or two or more types may be mixed and used.

  Among thermosetting resins, epoxy resins are particularly important because they are widely used as insulating resins because they are excellent in heat resistance, chemical resistance and electrical properties and are relatively inexpensive. Epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins and other bisphenol type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and bisphenol A novolak type epoxy resins. Type epoxy resin, cycloaliphatic epoxy resin, aliphatic chain epoxy resin, diglycidyl etherified product of biphenol, diglycidyl etherified product of naphthalenediol, diglycidyl etherified product of phenol, diglycidyl etherified product of alcohol, and these And alkyl-substituted products, halides, hydrogenated products, and the like. One type of epoxy resin may be used alone, or two or more types may be mixed and used. The curing agent used together with the epoxy resin can be used without limitation as long as it cures the epoxy resin. For example, polyfunctional phenols, polyfunctional alcohols, amines, imidazole compounds, acid anhydrides, organic There are phosphorus compounds and their halides. These epoxy resin curing agents may be used alone or in combination of two or more.

  The cyanate resin is a resin that generates a cured product having a triazine ring as a repeating unit by heating, and the cured product is excellent in dielectric characteristics, and is often used particularly when high-frequency characteristics are required. Examples of cyanate resins include 2,2-bis (4-cyanatophenyl) propane, bis (4-cyanatophenyl) ethane, 2,2-bis (3,5-dimethyl-4-cyanatophenyl) methane, , 2-bis (4-cyanatophenyl) -1,1,1,3,3,3-hexafluoropropane, α, α′-bis (4-cyanatophenyl) -m-diisopropylbenzene, phenol novolac and Examples include cyanate esterified products of alkylphenol novolac. Among these, 2,2-bis (4-cyanatophenyl) propane is preferable because it has a particularly good balance between the dielectric properties and curability of the cured product and is inexpensive. Moreover, a cyanate ester compound may be used individually by 1 type, and 2 or more types may be mixed and used for it. The cyanate ester compound used here may be partially oligomerized in advance to a trimer or a pentamer. Furthermore, a curing catalyst or a curing accelerator may be added to the cyanate resin. As the curing catalyst, metals such as manganese, iron, cobalt, nickel, copper, and zinc are used. Specifically, organic metal salts such as 2-ethylhexanoate, naphthenate, octylate, and acetylacetone are used. Used as organometallic complexes such as complexes. These may be used alone or in combination of two or more. Phenols are preferably used as the curing accelerator, and monofunctional phenols such as nonylphenol and paracumylphenol, bifunctional phenols such as bisphenol A, bisphenol F, and bisphenol S, or polyfunctional phenols such as phenol novolac and cresol novolac. Etc. can be used. These may be used alone or in combination of two or more.

  The resin composition used as the insulating material may be blended with a thermoplastic resin in consideration of dielectric properties, impact resistance, film processability, and the like. Examples of the thermoplastic resin include, but are not limited to, fluororesin, polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polycarbonate, polyether imide, polyether ether ketone, polyarylate, polyamide, polyamide imide, and polybutadiene. I don't mean. One type of thermoplastic resin may be used alone, or two or more types may be mixed and used.

  Among thermoplastic resins, blending polyphenylene ether and modified polyphenylene ether is useful because it improves the dielectric properties of the cured product. Examples of polyphenylene ether and modified polyphenylene ether include poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6-dimethyl-1,4-phenylene) ether and polystyrene alloyed polymer, poly Alloyed polymer of (2,6-dimethyl-1,4-phenylene) ether and styrene-butadiene copolymer, Alloyed polymer of poly (2,6-dimethyl-1,4-phenylene) ether and styrene-maleic anhydride copolymer Alloyed polymer of poly (2,6-dimethyl-1,4-phenylene) ether and polyamide, alloyed polymer of poly (2,6-dimethyl-1,4-phenylene) ether and styrene-butadiene-acrylonitrile copolymer, etc. Is mentioned. In addition, in order to impart reactivity and polymerizability to polyphenylene ether, functional groups such as amino groups, epoxy groups, carboxyl groups, styryl groups, and methacryl groups are introduced at the ends of polymer chains, or amino groups are introduced into the side chains of polymer chains. In addition, a functional group such as an epoxy group, a carboxyl group, a styryl group, or a methacryl group may be introduced.

  Among thermoplastic resins, polyamideimide resin is useful because it has excellent heat resistance and moisture resistance, and also has good adhesion to metal. Among the raw materials of polyamideimide, trimellitic anhydride and trimellitic anhydride monochloride are used as acid components, and metaphenylenediamine, paraphenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′- as amine components. Examples include, but are not limited to, diaminodiphenylmethane, bis [4- (aminophenoxy) phenyl] sulfone, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, and the like. In order to improve drying property, it may be modified with siloxane. In this case, siloxane diamine is used as the amino component. In consideration of film processability, it is preferable to use a molecular weight of 50,000 or more.

  An inorganic filler may be mixed in the resin composition used as the insulating material. Examples of the inorganic filler include alumina, aluminum hydroxide, magnesium hydroxide, clay, talc, antimony trioxide, antimony pentoxide, zinc oxide, fused silica, glass powder, quartz powder, and shirasu balloon. These inorganic fillers may be used alone or in combination of two or more.

  The resin composition used as the insulating material may contain an organic solvent. Organic solvents include aromatic hydrocarbon solvents such as benzene, toluene, xylene and trimethylbenzene; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran; isopropanol and butanol Suitable alcohol solvents; ether alcohol solvents such as 2-methoxyethanol and 2-butoxyethanol; amide solvents such as N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, etc. You may use together. When the prepreg is produced, the amount of solvent in the varnish is preferably in the range of 40 to 80% by weight, and the viscosity of the varnish is preferably in the range of 20 to 100 cP.

  The resin composition used as the insulating material may contain a flame retardant. Flame retardants include bromine compounds such as decabromodiphenyl ether, tetrabromobisphenol A, tetrabromophthalic anhydride, tribromophenol, triphenyl phosphate, tricresyl phosphate, trixyl phosphate, cresyl diphenyl phosphate, etc. Known metal compounds such as phosphorus compounds, magnesium hydroxide and aluminum hydroxide, red phosphorus and its modified products, antimony compounds such as antimony trioxide and antimony pentoxide, and triazine compounds such as melamine, cyanuric acid and melamine cyanurate Conventional flame retardants can be used.

  Various additives and fillers such as curing agents, curing accelerators, thermoplastic particles, colorants, UV-opaque agents, antioxidants, reducing agents, etc., as necessary, for resin compositions used as insulating materials Add and mix.

Usually, after impregnating or coating the base material so that the amount of the resin composition attached to the base material is 20 to 90% by weight in terms of the resin content of the dried prepreg, it is usually 1 at a temperature of 100 to 200 ° C. Heat-dry for ˜30 minutes to obtain a semi-cured (B-stage) prepreg. Usually, 1 to 20 sheets of this prepreg are stacked and heated and pressed in a configuration in which metal foils are arranged on both surfaces. As a molding condition, a method of a normal laminated plate can be applied. For example, a multi-stage press, a multi-stage vacuum press, continuous molding, an autoclave molding machine or the like is used, and a temperature is typically 100 to 250 ° C., a pressure is ^{2 to} 100 kg / cm ² , and heating is performed. Molding is performed for a time in the range of 0.1 to 5 hours, or by using a vacuum laminating apparatus or the like under the conditions of lamination at 50 to 150 ° C. and 0.1 to 5 MPa under reduced pressure or atmospheric pressure. Although the thickness of the prepreg layer which becomes an insulating layer changes with uses, the thing of the thickness of 0.1-5.0 mm is good normally.

As for the surface roughness of the metal foil used in the present invention, the 10-point average roughness (Rz) shown in JISB0601 is preferably 2.0 μm or less on both sides in view of electrical characteristics. Although copper foil, nickel foil, aluminum foil, etc. can be used for metal foil, copper foil is usually used. In the case of a copper sulfate bath, the production conditions of the copper foil are sulfuric acid 50-100 g / L, copper 30-100 g / L, liquid temperature 20 ° C.-80 ° C., current density 0.5-100 A / dm ² , pyrophosphoric acid In the case of a copper bath, the conditions of potassium pyrophosphate 100-700 g / L, copper 10-50 g / L, liquid temperature 30 ° C.-60 ° C., pH 8-12, current density 1-10 A / dm ² are commonly used. In some cases, various additives may be added in consideration of the physical properties and smoothness of copper.

More preferably, a metal foil having a peelable type with a thickness of 3.0 μm or less and a surface roughness Rz of 2.0 μm or less on both sides is used. Here, the peelable type metal foil is a metal foil having a carrier, which is a metal foil that can be peeled off by the carrier. For example, in the case of a peelable type ultra-thin copper foil, a metal oxide or organic layer to be a release layer is formed on a carrier foil having a thickness of 10 to 50 μm, and a sulfuric acid 50 to 100 g / h is used on the copper sulfate bath. L, copper 30-100 g / L, liquid temperature 20 ° C.-80 ° C., current density 0.5-100 A / dm ² condition, potassium pyrophosphate bath 100-700 g / L potassium pyrophosphate, copper 10-50 g / L, a liquid temperature of 30 ° C. to 60 ° C., a pH of 8 to 12, and a current density of 1 to 10 A / dm ² are produced by forming a metal foil having a thickness of 0.3 to 3.0 μm. When such a foil is used for the power feeding layer, the wiring formability is good as described later. Note that an etchable type copper foil having an aluminum carrier or a nickel carrier may be used instead of the peelable type.

The antirust treatment performed on the resin adhesive surface of the metal foil can be performed using any of nickel, tin, zinc, chromium, molybdenum, cobalt, or an alloy thereof. In these methods, a thin film is formed on a metal foil by sputtering, electroplating or electroless plating, but electroplating is preferable from the viewpoint of cost. Specifically, plating is performed using a plating layer containing one or more metal salts of nickel, tin, zinc, chromium, molybdenum, and cobalt. In order to facilitate the precipitation of metal ions, a complexing agent such as citrate, tartrate or sulfamic acid can be added in the required amount. The plating solution is usually used in an acidic region and is performed at a temperature of room temperature to 80 ° C. The plating is appropriately selected from a range of usually a current density of 0.1 to 10 A / dm ² and a current application time of 1 to 60 seconds, preferably 1 to 30 seconds. The amount of the rust-proofing metal varies depending on the type of metal, but is preferably 10 to 2000 μg / dm ^{2 in} total. If the rust preventive treatment is too thick, it may cause etching inhibition and deterioration of electrical characteristics, and if it is too thin, it may cause a reduction in peel strength with the resin.

Furthermore, if a chromate treatment layer is formed on the rust prevention treatment, it is useful because a reduction in peel strength with the resin can be suppressed. Specifically, it is performed using an aqueous solution containing hexavalent chromium ions. The chromate treatment can be performed by a simple immersion treatment, but is preferably performed by a cathode treatment. It is good to carry out on the conditions of sodium dichromate 0.1-50 g / L, pH 1-13, bath temperature 0-60 degreeC, current density 0.1-5 A / dm < ² >, and electrolysis time 0.1-100 second. It can also carry out using chromic acid or potassium dichromate instead of sodium dichromate.

In the present invention, it is preferable that a silane coupling agent is further adsorbed on the outermost layer of the metal foil. Examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane, epoxy-functional silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and N-2. Amino-functional silanes such as-(aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldimethoxysilane, vinyltrimethoxysilane, vinylphenyltrimethoxysilane, vinyltris (2- Olefin functional silane such as methoxyethoxy) silane, acrylic functional silane such as 3-acryloxypropyltrimethoxysilane, methacryl functional silane such as 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. And mercapto-functional silane is used. These may be used alone or in combination. These coupling agents are dissolved in a solvent such as water at a concentration of 0.1 to 15 g / L and applied to a metal foil at a temperature of room temperature to 50 ° C. or electrodeposited to be adsorbed. These silane coupling agents form a film by condensation bonding with a hydroxyl group of a rust-preventing metal on the surface of the metal foil. After the silane coupling treatment, a stable bond is formed by heating, ultraviolet irradiation or the like. If it is heating, it is dried at a temperature of 100 to 200 ° C. for 2 to 60 seconds. In the case of ultraviolet irradiation, it is performed in the range of 200 to 400 nm and 200 to 2500 mJ / cm ² .

  The combination of the resin composition and the silane coupling agent is preferably selected so that the functional group in the resin composition and the functional group of the silane coupling agent are chemically reacted by heating. For example, when an epoxy group is contained in the resin composition, the effect is more remarkably exhibited when aminofunctional silane is selected as the silane coupling agent. This is because the epoxy group and amino group easily form a strong chemical bond by heat, and this bond is extremely stable against heat and moisture. As a combination for forming a chemical bond in this manner, epoxy group-amino group, epoxy group-epoxy group, epoxy group-mercapto group, epoxy group-hydroxyl group, epoxy group-carboxyl group, epoxy group-cyanato group, amino group-hydroxyl group , Amino group-carboxyl group, amino group-cyanato group and the like.

  When the epoxy resin that is liquid at room temperature is included in the resin composition, the viscosity at the time of melting is greatly reduced, so that the wettability at the adhesion interface is improved, and the chemical reaction between the epoxy resin and the coupling agent is likely to occur. As a result, a strong peel strength can be obtained. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenol novolac type epoxy resin having an epoxy equivalent of about 200 are preferable.

  When the curing agent is included in the resin composition, it is particularly preferable to use a thermosetting latent curing agent as the curing agent. That is, when the functional group in the thermosetting resin and the functional group of the silane coupling agent chemically react, the reaction temperature of the functional group in the thermosetting resin and the functional group of the silane coupling agent is the same as that of the thermosetting resin. It is preferable to select the curing agent so that it is lower than the temperature at which the curing reaction is initiated. Thereby, since reaction of the functional group in a thermosetting resin and the functional group of a silane coupling agent can be performed preferentially and selectively, the adhesiveness of metal foil and a resin composition becomes higher. Thermosetting latent curing agents for resin compositions containing epoxy resins include dicyandiamide, dihydrazide compounds, imidazole compounds, amine-epoxy adducts and other solid dispersion-heat-dissolving curing agents, urea compounds, onium salts, boron trichloride -Reactive group block type curing agents such as amine salts and block carboxylic acid compounds.

  In addition, when a resin composition having a relative dielectric constant of 3.0 or less at 1 GHz or a dielectric loss tangent of 0.01 or less is used after the resin composition is cured, the dielectric loss in the wiring can be reduced, and transmission loss is further reduced. A small circuit can be formed. Examples of such a resin having excellent dielectric properties include polyphenylene ether and cyanate ester. When polyphenylene ether is used as a wiring board material, it is necessary to impart thermosetting properties in order to improve heat resistance and chemical resistance. For example, polyphenylene ether may be added to epoxy resin, cyanate ester resin, triazine-bis. There are a method of blending a thermosetting resin such as maleimide resin, and a method of introducing a polymerizable functional group such as a double bond or an epoxy group into the molecular chain of polyphenylene ether.

  When the cyanate resin is included in the resin composition, it is preferable to use nickel as a main component for the rust prevention treatment of the metal foil. This combination is useful in that there is little reduction in peel strength in the heat resistance deterioration test and moisture resistance deterioration test.

  The resin composition as described above and the metal foil whose surface is not roughened are laminated and integrated by a conventionally known method to obtain a laminate shown in FIG.

Next, through-holes 7 for interlayer connection are formed in the laminate (FIG. 2B). If the through hole diameter is 100 μm or more, processing by a drill is suitable, and if the through hole diameter is 100 μm or less, a gas laser such as CO ₂ , CO, or excimer, or a solid laser such as YAG is suitable.

Next, catalyst nuclei are provided on the metal foil and inside the through hole. For providing the catalyst nucleus, an activator neogant (trade name, manufactured by Atotech Japan Co., Ltd.), which is a palladium ion catalyst, and HS201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium colloid catalyst, are used. When the palladium catalyst is applied, conditioning treatment such as CLC-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is performed in advance. The amount of adsorption of the palladium catalyst varies greatly depending on the type of conditioning, the application method of the catalyst, and the application time. Here, in order to ensure connection reliability, it is necessary to attach palladium in the through hole. However, if excessive palladium is applied on the copper foil as will be described later, a problem occurs in a later etching process. Further, when the amount of metal palladium adsorbed on the copper foil is low, connection reliability is lowered. Adsorption onto a copper foil of the palladium catalyst in the present invention is in the range of 0.05~0.6μg / cm ^2, more preferably in the range of 0.05~0.3μg / cm ^2. The treatment temperature for adsorbing the palladium catalyst is preferably 10 to 40 ° C. By controlling the treatment time, the adsorption amount of the palladium catalyst on the copper foil can be controlled.

  Next, as shown in FIG. 2C, a thin electroless plating layer 8 is formed on the metal foil provided with catalyst nuclei and in the through holes. For this electroless plating, commercially available electroless copper plating such as CUST2000 (manufactured by Hitachi Chemical Co., Ltd., trade name) or CUST201 (product name of Hitachi Chemical Co., Ltd.) can be used. These electroless copper platings are mainly composed of copper sulfate, formalin, complexing agent and sodium hydroxide. The thickness of the plating is not limited as long as the next electroplating can be performed, and about 0.1 to 1 μm is sufficient.

  Next, as shown in FIG. 2 (d), after performing electroless plating, a plating resist 9 is formed. The thickness of the plating resist is preferably set to a thickness that is about the same as or thicker than the conductor to be subsequently plated. Resins that can be used for the plating resist include liquid resists such as PMER P-LA900PM (trade name, manufactured by Tokyo Ohka Co., Ltd.), HW-425 (trade name, Hitachi Chemical Co., Ltd.), RY-3025 (Hitachi Chemical). There are dry films such as Kogyo Co., Ltd. (trade name). A plating resist is not formed on the via hole and the portion to be a conductor circuit.

  Next, as shown in FIG. 2E, a circuit pattern 10 is formed by electroplating. For the electroplating, copper sulfate electroplating usually used for printed wiring boards can be used. The plating thickness may be used as a circuit conductor, and is preferably in the range of 1 to 100 μm, and more preferably in the range of 5 to 50 μm.

  Next, as shown in FIG. 2 (f), the resist is stripped using an alkaline stripping solution, sulfuric acid, or a commercially available resist stripping solution, and copper other than the pattern portion is removed by etching. In this case, etching is generally performed by high-pressure spraying or the like, but the exchange of the liquid is inevitably worsened for fine portions of the wiring. Therefore, it is desirable that the reaction between the copper and the etching solution is not diffusion-limited but reaction-limited. If the reaction between copper and the etchant is reaction-controlled, the etching rate does not change even if diffusion is further increased. That is, there is no difference in etching rate between a place where the liquid exchange is good and a place where the liquid exchange is bad. Specifically, an ammonium sulfate-based etching solution or an etching solution mainly containing hydrogen peroxide and an acid not containing a halogen element may be used. In particular, an etching solution mainly containing hydrogen peroxide and an acid not containing a halogen element is preferable. As the persulfate-based etching solution, for example, ammonium peroxodisulfate is used. When hydrogen peroxide is used as the oxidizing agent in the etching solution, the etching rate can be strictly controlled by controlling the hydrogen peroxide concentration. If a halogen element is mixed in the etching solution, the dissolution reaction tends to be diffusion-limited. As the acid not containing halogen, nitric acid, sulfuric acid, organic acid, and the like can be used, but sulfuric acid is preferable because it is inexpensive. Furthermore, when sulfuric acid and hydrogen peroxide are the main components, the respective concentrations are preferably 5 to 300 g / L and 5 to 200 g / L from the viewpoints of etching rate and liquid stability. Here, if the palladium catalyst is excessively present on the copper foil, a problem that the palladium catalyst layer is excessively etched occurs. This phenomenon is particularly noticeable when an etching solution containing sulfuric acid and hydrogen peroxide as main components is used. After the etching is completed, the undercut is preferably within 5 μm on one side.

  A two-layer core substrate is completed by the method described above. Further, when a four-layer board is produced, the inner layer conductor circuit 1 on the surface of the core substrate is roughened to improve the adhesion with the interlayer resin insulating layer formed on the copper pattern. Specifically, there are a method of forming acicular electroless plating on the core substrate, a method of oxidizing (blackening) -reducing the inner layer copper pattern, a method of etching the inner layer copper pattern, and the like.

  Next, a resin with a single-sided metal foil is laminated on the core substrate as shown in FIG. The thickness of the insulating layer 11 is about 10 to 100 μm, preferably 20 to 60 μm, and the thickness of the metal foil 12 is preferably 0.3 to 3 μm. Resin used for the production of resin with single-sided metal foil, copper foil is the same as that for laminates, and resin varnish is applied to metal foil using a kiss coater, roll coater, comma coater, etc., or a film-like resin Is laminated to a metal foil. When the resin varnish is applied to the metal foil, it is then heated and dried, but the condition is suitably 1 to 30 minutes at a temperature of 100 to 200 ° C., and in the resin composition after heating and drying. The residual solvent amount is suitably about 0.2 to 10%. When laminating a film-like resin on a metal foil, vacuum or atmospheric pressure conditions are suitable under the conditions of 50 to 150 ° C. and 0.1 to 5 MPa. There is also a method of laminating and pressing a core substrate, a prepreg, and a copper foil.

Next, as shown in FIG. 2 (h), IVH 13 is formed on the interlayer resin insulating layer from above the metal foil. As a method of forming IVH, it is preferable to use a laser. Examples of the laser that can be used here include gas lasers such as CO ₂ , CO, and excimer, and solid lasers such as YAG. Since a CO ₂ laser can easily obtain a large output, it is suitable for processing IVH of φ50 μm or more. When processing a fine IVH of φ50 μm or less, a YAG laser with a shorter wavelength and good condensing property is suitable.

  Next, the resin residue inside IVH is removed using an oxidizing agent such as permanganate, chromate, or chromic acid.

The catalyst nuclei are then applied on the metal foil and inside the IVH. Adsorption onto copper foil Again palladium catalyst is in the range of 0.05~0.6μg / cm ^2, more preferably in the range of 0.05~0.3μg / cm ^2.

  Next, as shown in FIG. 2 (i), a thin electroless plating layer 14 is formed on the metal foil provided with catalyst nuclei and inside the IVH. For this electroless plating, commercially available electroless copper plating such as CUST2000 (manufactured by Hitachi Chemical Co., Ltd., trade name) or CUST201 (product name of Hitachi Chemical Co., Ltd.) can be used. These electroless copper platings are mainly composed of copper sulfate, formalin, complexing agent and sodium hydroxide. The thickness of the plating is not limited as long as the next electroplating can be performed, and about 0.1 to 1 μm is sufficient.

  Next, as shown in FIG. 2 (j), after performing electroless plating, a plating resist 15 is formed. The thickness of the plating resist is preferably set to a thickness that is about the same as or thicker than the conductor to be subsequently plated. Resins that can be used for the plating resist include liquid resists such as PMER P-LA900PM (trade name, manufactured by Tokyo Ohka Co., Ltd.), HW-425 (trade name, Hitachi Chemical Co., Ltd.), RY-3025 (Hitachi Chemical). There are dry films such as Kogyo Co., Ltd. (trade name). A plating resist is not formed on the via hole and the portion to be a conductor circuit.

  Next, as shown in FIG. 2 (k), a circuit pattern 16 is formed by electroplating. For the electroplating, copper sulfate electroplating usually used for printed wiring boards can be used. The plating thickness may be used as a circuit conductor, and is preferably in the range of 1 to 100 μm, and more preferably in the range of 5 to 50 μm.

  Next, the resist is stripped using an alkaline stripping solution, sulfuric acid, or a commercially available resist stripping solution.

  Next, the formation of the circuit is completed by removing the copper other than the pattern portion by using an etchant preferably containing 10 to 300 g / L sulfuric acid and 10 to 200 g / L hydrogen peroxide as main components (FIG. 2 ( l)). After the etching is completed, the undercut is preferably within 5 μm on one side.

  Furthermore, gold plating can be performed on the circuit. As a gold plating method, the conductor interface is activated with an activation treatment solution such as SA-100 (manufactured by Hitachi Chemical Co., Ltd., trade name), and NIPS-100 (manufactured by Hitachi Chemical Co., Ltd., product). Electroless nickel plating such as HGS-100 (made by Hitachi Chemical Co., Ltd., trade name) and HGS- Electroless gold plating such as 2000 (manufactured by Hitachi Chemical Co., Ltd., trade name) is performed for about 0.1 to 1 μm.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG.

( Comparative Example 3 )
In FIG. 3, the metal foil used as the metal foil 18 was produced as follows.

(Metal foil)
A chromium plating layer (peeling layer) with a thickness of 1.0 mg / dm ² was formed by continuously performing chromium plating on the light selective surface of an electrolytic copper foil (carrier copper foil) having a width of 510 mm and a thickness of 35 μm under the following conditions. . The surface roughness after formation of the chrome plating was Rz = 0.5 μm. The surface roughness was measured based on JIS-B-0601.

Chromium plating conditions / solution composition: chromium trioxide 250 g / L, sulfuric acid 2.5 g / L
・ Bath temperature: 25 ° C
・ Anode: Lead ・ Current density 20A / dm ²
Next, electrolytic copper plating with a thickness of 1.0 μm was performed under the photoselective plating conditions shown below. The surface roughness of the metal foil after completion of the electrolytic copper plating was Rz = 0.6 μm.

Copper sulfate plating conditions / solution composition: copper sulfate pentahydrate 100g / L, sulfuric acid 150g / L, chloride ion 30ppm
・ Bath temperature: 25 ° C
・ Anode: Lead ・ Current density: 10 A / dm ²
Next, as shown below, zinc rust prevention treatment was performed by electroplating.

・ Liquid composition: Zinc 20g / L, Sulfuric acid 70g / L
・ Bath temperature: 40 ℃
・ Anode: Lead ・ Current density: 15 A / dm ²
Electrolysis time: 10 seconds Next, the following chromate treatment was performed.

・ Liquid composition: Chromic acid 5.0g / L
・ PH 11.5
・ Bath temperature: 55 ℃
-Anode: Lead-Immersion time: 5 seconds Next, the following silane coupling treatment was performed.

Liquid composition: 3-aminopropyltrimethoxysilane 5.0 g / L
・ Liquid temperature 25 ℃
Immersion time 10 seconds After the silane coupling treatment, the metal foil was dried at 120 ° C. to adsorb the coupling agent on the surface of the metal foil. At that time, the surface roughness of the metal foil was Rz = 0.6 μm.

Next, the resin composition shown below was created.

(Resin composition)
20% by weight of polyphenylene ether resin (PKN4752, trade name manufactured by GE Plastics, Inc.), 40% by weight of 2,2-bis (4-cyanatophenyl) propane (ArocyB-10, trade name of Asahi Ciba Co., Ltd.), Phosphorus-containing phenol compound (HCA-HQ, trade name, manufactured by Sanko Chemical Co., Ltd.) 8% by weight, manganese naphthenate (Mn content = 6% by weight, manufactured by Nippon Chemical Industry Co., Ltd.) 0.1% by weight, 2,2- Bis (4-glycidylphenyl) propane (DER331L, trade name of Dow Chemical Japan Co., Ltd.) 32% by weight was dissolved in toluene at 80 ° C. to prepare a polyphenylene ether-cyanate resin composition varnish.

A 0.2 mm thick glass cloth (basis weight 210 g / m ² ) was impregnated with the resin composition and dried at 120 ° C. for 5 minutes to obtain a prepreg. The four prepregs and the metal foils already prepared on the top and bottom are laminated and press-molded at 170 ° C. and 2.45 MPa for 1 hour, and a copper made of the insulating layer 17 and the metal foil 18 as shown in FIG. A tension laminate was produced.

  As shown in FIG. 3 (b), a through-hole 19 having a diameter of 80 μm was drilled from a metal foil with a carbon dioxide impact laser drilling machine L-500 (trade name, manufactured by Sumitomo Heavy Industries, Ltd.), and permanganate. Smear was removed by dipping in a mixed aqueous solution of potassium 65 g / liter and sodium hydroxide 40 g / liter at a liquid temperature of 70 ° C. for 20 minutes.

Thereafter, HS-201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium catalyst, was applied, and then CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used, and the liquid temperature was 25 ° C., 30 minutes. The electroless copper plating was performed under the conditions described above to form an electroless copper plating layer 20 having a thickness of 0.5 μm as shown in FIG. The conditions for applying the palladium catalyst are shown in Table 1.

  As shown in FIG. 3D, a dry film photoresist, RY-3025 (trade name, manufactured by Hitachi Chemical Co., Ltd.), is laminated on the surface of the electroless plating layer 20, and a place where electrolytic copper plating is performed. The plating resist 21 was formed by exposing and developing ultraviolet rays through the masked photomask.

As shown in Fig. 3 (e), using a copper sulfate bath, electrolytic copper plating is performed at a liquid temperature of 25 ° C and a current density of 1.0 A / dm ² for about 20 µm. Minimum circuit conductor width / circuit conductor spacing The circuit pattern 22 was formed so that (L / S) = 23/17 μm.

Next, as shown in FIG. 3 (f), after removing the dry film with HTO (trade name, manufactured by Nichigo Morton Co., Ltd.) which is a resist stripping solution, H ₂ SO ₄ 20 g / L, H ₂ O ₂ Copper other than the pattern portion was removed by etching using an etching solution having a composition of 10 g / L. The minimum circuit conductor width / circuit conductor interval (L / S) after etching was 20/20 μm.

(Example 2)
A substrate was prepared in the same manner as in Comparative Example 3 except that the treatment time of HS-201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium catalyst, was set to 2 minutes.

( Comparative Example 4 )
A substrate was prepared in the same manner as in Comparative Example 3 except that the application conditions of HS-201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium catalyst, were set as shown in Table 2.

(Example 4)
A substrate was prepared in the same manner as in Comparative Example 3 except that an alkali ion catalyst was used as the palladium catalyst and the application conditions were set as shown in Table 3.

(Example 5)
A substrate was produced in the same manner as in Example 4 except that the treatment time of activator Neogant 834 (trade name, manufactured by Atotech Japan Co., Ltd.), which is a palladium catalyst, was set to 1 minute.

(Comparative Example 1)
A substrate was prepared in the same manner as in Comparative Example 4 except that the treatment time of HS-201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium catalyst, was changed to 20 minutes.

(Comparative Example 2)
A substrate was prepared in the same manner as in Example 4 except that the treatment time of activator Neogant 834 (trade name, manufactured by Atotech Japan Co., Ltd.), which is a palladium catalyst, was changed to 30 seconds.

(Measurement condition)
(1) Amount of palladium adsorbed on copper foil
The conductor part (that is, the part where the resist was not formed) of the substrate produced by the methods of Examples 2, 4 and 5 and Comparative Examples 1 to 4 was cut out in unit area (1 dm ² ) and immersed in 50% aqua regia for 4 hours. After that, the palladium catalyst concentration in 50% aqua regia was quantified by atomic absorption spectroscopy. A Z-6000 (manufactured by Hitachi, Ltd., trade name), which is a polarized Zeeman atomic absorption spectrophotometer, was used as a measuring apparatus.

(2) Undercut amount The substrate was cut, and the undercut amount of the wiring in the portion of the minimum circuit conductor width / circuit conductor interval (L / S) = 20/20 μm was measured.

(3) Wiring peeling It was confirmed whether or not wiring peeling occurred in the portion of the minimum circuit conductor width / circuit conductor interval (L / S) = 20/20 μm.

(4) Connection reliability
The connection reliability test of the board | substrate produced by the method of Examples 2, 4, and 5, and Comparative Examples 1-4 was done. The pattern shown in FIG. 4 was used for connection reliability evaluation. In FIG. 4, a circuit pattern 23, an insulating layer 24, and a through-through hole 25 are shown. In connection reliability evaluation, −65 ° C. for 30 minutes → 125 ° C. for 30 minutes was defined as one cycle, and if the resistance value change after 1000 cycles was within ± 10% of the initial value, the connection was evaluated as acceptable.

(result)
Table 5 shows the evaluation results of the substrates produced by the methods of Examples 2, 4 and 5, and Comparative Examples 1 to 4 . As shown in Table 5, the substrate produced according to the present invention had a small amount of undercut, no wiring peeling, and good connection reliability.

It is sectional drawing of the wiring used for defining an undercut. It is sectional drawing which shows an example of the manufacturing process of the printed wiring board by this invention. FIG. 3 is a cross-sectional view showing a manufacturing process of the printed wiring board of Example 1. It is sectional drawing of a connection reliability evaluation pattern.

Explanation of symbols

1 Electrolytic copper
2 Electroless copper
3 Metal foil
4 Resin
5 prepreg
6 Metal foil
7 Through-hole
8 Electroless plating layer
9 Plating resist
10 Circuit pattern
11 Insulation layer
12 Metal foil
13 IVH
14 Electroless plating layer
15 Plating resist
16 Circuit pattern
17 Insulation layer
18 Copper foil
19 Through-hole
20 Electroless plating layer
21 plating resist
22 circuit patterns
23 circuit patterns
24 insulation layer
25 through holes

Claims (5)

After applying a palladium catalyst on the metal foil fixed on the insulating resin, electroless copper plating, forming a resist for pattern formation on the electroless copper plating, forming a circuit by pattern electroplating, and then resisting removal of the method for manufacturing a printed wiring board having the step of etching away the copper other than the circuit part, Tsu der range adsorption amount of 0.05~ 0.3 μg / cm ² onto the metal foil of the metal palladium A method of manufacturing a printed wiring board comprising using a chemical solution mainly composed of sulfuric acid / hydrogen peroxide in the step of etching away copper other than the circuit portion . The method for producing a printed wiring board according to claim 1 , wherein the sulfuric acid concentration is 5 to 300 g / L, and the hydrogen peroxide concentration is 5 to 200 g / L. Method for manufacturing a printed wiring board according to any one of claims 1-2, characterized in that the surface roughness of the metal foil (Rz) is 2μm or less on both sides. The thickness of the said metal foil is 3 micrometers or less, The manufacturing method of the printed wiring board in any one of Claims 1-3 characterized by the above-mentioned. Printed wiring board manufactured by the method of any of claims 1-4 in which the undercut amount of the electroless copper plating portion is equal to or is within 5 [mu] m.

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