JP5018181B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

The present invention relates to a method for manufacturing a multilayer printed wiring board. More specifically, the present invention relates to a method for manufacturing a multilayer printed wiring board in which through-hole filling and insulating layer formation are collectively performed.

  Conventionally, in the manufacture of multilayer printed wiring boards by the build-up method, filling the through hole existing in the core substrate with a filling agent (filling ink or conductive paste), thermosetting, and flatness around the through hole opening In order to ensure this, the periphery of the through hole was polished (Patent Document 1). As a polishing step after the hole filling step, a method is known in which both surfaces of the substrate are polished by buffing with a ceramic buff or belt sander polishing, and the rising portion of the hole filling resin protruding from the substrate surface is scraped off (Patent Document 2). By flattening the insulating layer by the polishing process, further multilayering is possible. When an insulating layer is formed on the core substrate without planarizing the periphery of the through hole, resist formation on the insulating layer and opening formation by laser processing are not accurately performed, leading to the occurrence of defects.

  Since the smoothing by the hole filling step and the polishing step is complicated and complicated, a more efficient method is demanded. On the other hand, a method of simultaneously filling a through hole and forming an insulating layer with an adhesive film in which a resin composition layer is provided on a support is known (Patent Document 3). However, in this method, a dent tends to occur in the insulating layer portion on the through hole due to curing shrinkage of the resin composition, and it is generally difficult to form a smooth insulating layer on the through hole.

  On the other hand, an adhesive film with a copper foil is known as an adhesive film used in a method for producing a multilayer printed wiring board. In this method, a copper foil is used as it is to form a circuit as a conductor layer, and a resin composition layer is formed on the matte surface of the copper foil in order to maintain the adhesion between the conductor layer and the insulating layer. However, when copper foil is used as a conductor layer as it is, it is disadvantageous for fine wiring formation, and in the production of multilayer printed wiring boards that require fine wiring formation, the conductor layer is formed by plating by the semi-additive method Circuit formation is the mainstream later.

Japanese Patent Laid-Open No. 2001-127435 JP 2003-133727 A Japanese Patent Laid-Open No. 11-87927

  The present invention provides an insulating layer formed in a method of manufacturing a multilayer printed wiring board in which an insulating layer is formed by simultaneously filling a through hole and laminating a substrate surface with an adhesive film, and further, a circuit is formed by a semi-additive method. It aims at providing the manufacturing method of a multilayer printed wiring board which suppresses the dent on the through hole of this.

  As a result of diligent research to solve the above problems, the present invention uses a specific adhesive film with a metal foil provided with a resin composition layer on the glossy surface of a metal foil in the production of a multilayer printed wiring board, and a vacuum laminator. The through hole is filled simultaneously with the lamination of the adhesive film, the thermosetting resin composition is thermally cured, and then the metal foil is removed, so that the dent on the through hole of the insulating layer can be suppressed and smooth. As a result, it was found that an insulating layer excellent in performance and suitable for circuit formation by a semi-additive process can be formed, and the present invention has been completed.

That is, the present invention is as follows.
[1] A method for producing a multilayer printed wiring board using an adhesive film in which a resin composition layer made of a thermosetting resin composition is formed on a support, and includes at least the following steps 1) to 4):
1) A step of bringing a resin composition layer of an adhesive film into contact with a substrate having a through hole, heating and pressing under reduced pressure by a vacuum laminator, and filling the through hole simultaneously with the lamination of the adhesive film;
2) a step of thermosetting the thermosetting resin composition in a state in which the resin composition is in contact with the glossy surface of the metal foil having a thickness of 20 μm or more to form an insulating layer;
3) A step of removing the metal foil after thermosetting,
4) a step of roughening the surface of the insulating layer with an oxidizing agent, and 5) a step of forming a conductor layer by plating on the surface of the roughened insulating layer,
A method for producing a multilayer printed wiring board, comprising:
[2] The method according to [1] above, wherein the adhesive film is an adhesive film having a metal foil having a thickness of 20 μm or more as a support and a resin composition layer formed on the glossy surface of the metal foil.
[3] The method according to [1] or [2] above, wherein the metal foil is selected from electrolytic copper foil, rolled copper foil, or aluminum foil.
[4] The manufacturing method according to any one of [1] to [3], wherein the thickness of the metal foil is 20 μm or more and 75 μm or less.
[5] The method according to any one of [1] to [4] above, wherein the thickness of the resin composition layer of the adhesive film is 15 to 100 μm.
[6] The step of thermosetting the thermosetting resin includes two steps: a step of heat-treating the resin composition layer at a temperature of 70 ° C. to 140 ° C., and a step of thermosetting at a temperature higher than the temperature of the heat treatment. The method according to any one of [1] to [5], which is performed.
[7] The method according to any one of [1] to [6], including a step of forming a via hole in the insulating layer after removing the metal foil.

  According to the manufacturing method of the present invention, an insulating layer in which a depression on a through hole is suppressed can be easily formed on a substrate having a through hole.

  A known support may be used as the support for the adhesive film in the present invention, and is not particularly limited. For example, a stretched PET film having a thickness of 30 to 125 μm can be used, but the thickness used in the subsequent step is also included. A metal foil having a gloss surface of 20 μm or more is preferred. As the metal foil, electrolytic copper foil, rolled copper foil, aluminum foil or the like can be used. The electrolytic copper foil has an uneven matte surface and a flat glossy surface. The rolled copper foil is glossy on both sides. In addition, aluminum foil usually has a glossy surface and a matte surface due to the characteristics of a production method in which two aluminum foils are rolled by doubling rolling. In the present invention, these metal foils are preferably used as a support for an adhesive film, and a resin composition layer is formed on the glossy surface of the metal foil. In the present invention, the metal foil used as the support is removed after the thermosetting resin composition constituting the resin composition layer is thermally cured to form an insulating layer. When the resin composition layer is formed on the mat surface, the surface of the insulating layer formed after removal of the metal foil will have irregularities reflecting the mat surface, but then the surface of the insulating layer that also serves as a desmear process is roughened. For this reason, the surface of the insulating layer is excessively roughened, making it difficult to form a fine circuit.

  The thickness of metal foil shall be 20 micrometers or more from a viewpoint of fully suppressing the insulating layer dent on a through hole. If the thickness of the metal foil is too large, the embedding property of the resin composition in the circuit tends to decrease, and the load of the etching process increases, which is not preferable in terms of cost. The following is preferable.

  As the thermosetting resin composition used for the resin composition layer of the adhesive film, it can be formed into a film by forming a layer on the support, has a certain fluidity when laminated with a vacuum laminator, There is no particular limitation as long as hole filling and substrate surface coating are possible.

  The thermosetting resin composition used for the resin composition layer can be used without particular limitation as long as the cured product has sufficient hardness and insulation properties, such as epoxy resin, cyanate ester resin, phenol resin. A composition in which at least the curing agent is blended with a thermosetting resin such as a bismaleimide-triazine resin, a polyimide resin, an acrylic resin, or a vinylbenzyl resin is used. However, a composition in which the thermosetting resin is an epoxy resin is used. A composition containing at least (a) an epoxy resin, (b) a thermoplastic resin, and (c) a curing agent is more preferable.

  (a) Examples of the epoxy resin include bisphenol A type epoxy resin, biphenyl type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, bisphenol F type epoxy resin, phosphorus-containing epoxy resin, bisphenol S type epoxy resin, and alicyclic ring Epoxy resin, aliphatic chain epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, epoxy resin having butadiene structure, diglycidyl etherified product of bisphenol, diglycidyl ether of naphthalenediol , Glycidyl etherification products of phenols, diglycidyl etherification products of alcohols, and alkyl-substituted products, halides and hydrogenated products of these epoxy resins It is below. These epoxy resins may be used alone or in combination of two or more.

  Among these, the epoxy resin has a bisphenol A type epoxy resin, a naphthol type epoxy resin, a naphthalene type epoxy resin, a biphenyl type epoxy resin, and a butadiene structure from the viewpoint of heat resistance, insulation reliability, and adhesion to a metal film. Epoxy resins are preferred. Specifically, for example, liquid bisphenol A type epoxy resin (“Epicoat 828EL” manufactured by Japan Epoxy Resin Co., Ltd.), naphthalene type tetrafunctional epoxy resin (“HP4700” manufactured by Dainippon Ink & Chemicals, Inc.), naphthol type Epoxy resin (“ESN-475V” manufactured by Toto Kasei Co., Ltd.), epoxy resin having a butadiene structure (“PB-3600” manufactured by Daicel Chemical Industries, Ltd.), epoxy resin having a biphenyl structure (Nippon Kayaku Co., Ltd.) “NC3000H” manufactured by Japan Epoxy Resin Co., Ltd. “YX4000”).

  (b) The thermoplastic resin is blended for the purpose of imparting appropriate flexibility to the cured composition, for example, phenoxy resin, polyvinyl acetal resin, polyimide, polyamideimide, polyethersulfone. And polysulfone. These may be used alone or in combination of two or more. The thermoplastic resin is preferably blended at a rate of 0.5 to 60% by mass, more preferably 3 to 50% by mass, when the nonvolatile component of the thermosetting resin composition is 100% by mass. When the blending ratio of the thermoplastic resin is less than 0.5% by mass, since the viscosity of the resin composition is low, it tends to be difficult to form a uniform thermosetting resin composition layer. The viscosity of the resin composition becomes too high, and it tends to be difficult to embed it in the wiring pattern on the substrate.

  Specific examples of the phenoxy resin include, for example, FX280, FX293 manufactured by Toto Kasei Co., Ltd., YX8100, YL6954, YL6974 manufactured by Japan Epoxy Resin Co., Ltd., and the like.

  The polyvinyl acetal resin is preferably a polyvinyl butyral resin, and specific examples of the polyvinyl acetal resin include those manufactured by Denki Kagaku Kogyo Co., Ltd., Electric Butyral 4000-2, 5000-A, 6000-C, 6000-EP, Sekisui Chemical Co., Ltd. ) Made S-Rec BH series, BX series, KS series, BL series, BM series and the like.

  Specific examples of polyimide include polyimide “Rika Coat SN20” and “Rika Coat PN20” manufactured by Shin Nippon Rika Co., Ltd. Also, a linear polyimide obtained by reacting a difunctional hydroxy group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride (described in JP-A-2006-37083), a polysiloxane skeleton-containing polyimide (JP-A-2002-2002). And modified polyimides such as those described in JP-A No. 12667 and JP-A No. 2000-319386.

  Specific examples of the polyamide imide include polyamide imides “Bilomax HR11NN” and “Bilomax HR16NN” manufactured by Toyobo Co., Ltd. In addition, modified polyamideimides such as polysiloxane skeleton-containing polyamideimides “KS9100” and “KS9300” manufactured by Hitachi Chemical Co., Ltd. may be mentioned.

  Specific examples of the polyethersulfone include polyethersulfone “PES5003P” manufactured by Sumitomo Chemical Co., Ltd.

  Specific examples of the polysulfone include polyethersulfone “P1700” and “P3500” manufactured by Solven Advanced Polymers Co., Ltd.

  (c) Examples of the curing agent include amine curing agents, guanidine curing agents, imidazole curing agents, phenol curing agents, naphthol curing agents, acid anhydride curing agents, or epoxy adducts and microencapsulation thereof. And cyanate ester resins. Of these, phenol-based curing agents, naphthol-based curing agents, and cyanate ester resins are preferable. In addition, in this invention, a hardening | curing agent may be 1 type, or may use 2 or more types together.

  Specific examples of the phenol-based curing agent and naphthol-based curing agent include, for example, MEH-7700, MEH-7810, MEH-7851 (manufactured by Meiwa Kasei Co., Ltd.), NHN, CBN, GPH (manufactured by Nippon Kayaku Co., Ltd.), SN170, SN180, SN190, SN475, SN485, SN495, SN375, SN395 (manufactured by Tohto Kasei Co., Ltd.), LA7052, LA7054 (manufactured by Dainippon Ink & Chemicals, Inc.), and the like.

  Specific examples of the cyanate ester resin include, for example, bisphenol A dicyanate, polyphenol cyanate (oligo (3-methylene-1,5-phenylene cyanate), 4,4′-methylenebis (2,6-dimethylphenyl cyanate), 4,4′-ethylidenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis (4-cyanate) phenylpropane, 1,1-bis (4-cyanatephenylmethane), bis (4-cyanate-3, Bifunctional cyanate resins such as 5-dimethylphenyl) methane, 1,3-bis (4-cyanatephenyl-1- (methylethylidene)) benzene, bis (4-cyanatephenyl) thioether, bis (4-cyanatephenyl) ether , Phenol novolac Examples include polyfunctional cyanate resins derived from cresol novolac, prepolymers in which these cyanate resins are partially triazines, etc. Commercially available cyanate ester resins include phenol novolac type polyfunctional cyanate ester resins (Lonza Japan ( "PT30" manufactured by Co., Ltd., cyanate equivalent 124), and prepolymers obtained by triazine formation of some or all of bisphenol A dicyanate ("BA230" manufactured by Lonza Japan Co., Ltd., cyanate equivalent 232) and the like. It is done.

  In the case of a phenolic curing agent or a naphtholic curing agent, the blending ratio of (a) epoxy resin and (c) curing agent is such that the phenolic hydroxyl group equivalent of these curing agents is 0.4 to 1 with respect to the epoxy equivalent 1 of the epoxy resin. A ratio in the range of 2.0 is preferable, and a ratio in the range of 0.5 to 1.0 is more preferable. In the case of a cyanate ester resin, a ratio in which the cyanate equivalent is in the range of 0.3 to 3.3 with respect to the epoxy equivalent 1 is preferable, and a ratio in the range of 0.5 to 2 is more preferable. When the reactive group equivalent ratio is outside this range, the mechanical strength and water resistance of the cured product tend to be lowered.

  In addition to (c) the curing agent, (d) a curing accelerator can be further blended in the thermosetting resin composition. Examples of such curing accelerators include imidazole compounds and organic phosphine compounds, and specific examples include 2-methylimidazole and triphenylphosphine. (d) When using a hardening accelerator, it is preferable to use in 0.1-3.0 mass% with respect to an epoxy resin. In the case of using a cyanate ester resin as an epoxy resin curing agent, an organometallic compound conventionally used as a curing catalyst in a system in which an epoxy resin composition and a cyanate compound are used together for the purpose of shortening the curing time. May be added. Organic metal compounds include organic copper compounds such as copper (II) acetylacetonate, organic zinc compounds such as zinc (II) acetylacetonate, and organic such as cobalt (II) acetylacetonate and cobalt (III) acetylacetonate. A cobalt compound etc. are mentioned. The addition amount of the organometallic compound is usually in the range of 10 to 500 ppm, preferably 25 to 200 ppm in terms of metal with respect to the cyanate ester resin.

  In addition, the thermosetting resin composition may contain (e) an inorganic filler in order to reduce the thermal expansion of the post-curing composition. Examples of the inorganic filler include silica, alumina, mica, mica, silicate, barium sulfate, magnesium hydroxide, and titanium oxide. Silica and alumina are preferable, and silica is particularly preferable. The inorganic filler preferably has an average particle size of 3 μm or less, more preferably 0.6 μm or less, from the viewpoint of insulation reliability. On the other hand, the lower limit of the average particle diameter is not particularly limited, but is preferably 0.1 μm or more. The content of the inorganic filler in the thermosetting resin composition is preferably 0 to 60% by mass, more preferably 20 to 50% by mass when the nonvolatile component of the thermosetting resin composition is 100% by mass. %. When the content of the inorganic filler is less than 20% by weight, the effect of lowering the thermal expansion coefficient tends not to be sufficiently exhibited. When the content of the inorganic filler exceeds 60% by weight, the mechanical strength of the cured product decreases. It becomes a tendency to do.

  In recent high-density package substrates and the like, the insulating resin layer has been made thinner due to the requirement for characteristic impedance. Therefore, when the through hole is filled with the adhesive film, the problem of the depression of the insulating layer on the through hole tends to become more prominent. In the present invention, the thickness of the resin composition layer is usually selected from the range of conductor layer thickness + (10 to 65) μm from the viewpoint of reducing the thickness. From the viewpoint of interlayer insulation reliability and the like, the thickness of the resin composition layer is usually in the range of 15 to 100 μm, preferably 15 to 80 μm, and more preferably 25 to 60 μm.

  As for the adhesive film in this invention, the surface where the support body of the resin composition layer is not closely_contact | adhering may be protected by the protective film. As the protective film, a plastic film having a thickness of 1 to 40 μm, such as polyethylene, polypropylene, polyethylene terephthalate, and polyester, is preferably used.

  Examples of the substrate having a through hole suitable for application of the production method of the present invention include the following. A board having a plate thickness of 0.05 to 0.2 mmt and a through hole diameter of 0.5 mm or less, a board thickness of 0.3 mmt or less and a through hole diameter of 0.35 mm or less, a plate thickness of 0.4 mmt or less A substrate having a through hole diameter of 0.27 mm or less, a plate thickness of 0.6 mmt or less, and a through hole diameter of 0.22 mm or less, a substrate having a plate thickness of 0.8 mmt or less and a through hole diameter of 0.17 mm or less.

  In the present invention, the resin composition layer of the adhesive film is brought into contact with a substrate having a through hole, and heated and pressurized under reduced pressure by a vacuum laminator to fill the through hole simultaneously with the lamination of the adhesive film. When the resin composition layer of the adhesive film is protected by a protective film, these are peeled and then laminated (laminated) on both sides of the substrate so that the resin composition layer is in direct contact with the substrate. The laminating method may be a batch method or a continuous method using a roll. In addition, the adhesive film and the substrate may be heated (preheated) as necessary before lamination. In addition, when the support used for the adhesive film is not a metal foil having a glossy surface with a thickness of 20 μm or more, after laminating the adhesive film, the support is peeled off before the heat treatment, and the laminated resin A metal foil having a glossy surface with a thickness of 20 μm or more may be laminated again from above the composition layer so that the glossy surface is in contact with the resin composition layer.

Lamination conditions are preferably a pressure bonding temperature (laminating temperature) of 70 to 140 ° C., a pressure bonding pressure of preferably 1 to 11 kgf / cm 2 (9.8 × 10 ^{4 to} 107.9 × 10 ⁴ N / m 2), and air pressure. Lamination is preferably performed under a reduced pressure of 20 mmHg (26.7 hPa) or less.

  A commercially available vacuum laminator can be used. Commercially available vacuum laminators include, for example, a vacuum applicator manufactured by Nichigo-Morton Co., Ltd., a vacuum pressurizing laminator manufactured by Meiki Seisakusho, a roll dry coater manufactured by Hitachi Industries, Ltd., Hitachi AIC Co., Ltd. ) Made vacuum laminator and the like.

  The substrate in the present invention is not particularly limited as long as it is a substrate having a through hole. However, the substrate is mainly a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, or the like. In this case, it refers to a substrate (a so-called core substrate) having through holes and having a conductor layer (circuit) patterned on one or both sides. In addition, it is preferable from the viewpoint of the adhesiveness of the insulating layer to the substrate that the surface of the conductor layer has been previously roughened by blackening or the like.

  After laminating the adhesive film, the step of thermosetting the thermosetting resin includes a step of heat-treating the resin composition layer at a temperature of 70 ° C. to 140 ° C. from the viewpoint of suppressing dents on the through hole, and It is preferable to carry out in two stages of the process of thermosetting at a temperature higher than the temperature. In the step of heat-treating the thermosetting resin composition at a temperature of 70 ° C. or more and 140 ° C. or less of the thermosetting resin composition before curing the thermosetting resin composition, the temperature of the heat treatment is preferably Is selected from the range of 70 to 130 ° C, more preferably 80 to 125 ° C. The time for the heat treatment is not particularly limited, and is usually selected from 5 minutes to 6 hours, preferably from 10 minutes to 5 hours, preferably from 20 minutes to 4 hours. The lower the temperature of the heat treatment, the longer the time required for the heat treatment.

  In the subsequent thermosetting process, the thermosetting resin composition is thermoset at a temperature higher than the temperature of the heat treatment process to form an insulating layer. The curing temperature and curing time vary depending on the type of the thermosetting resin composition, but are preferably selected in the range of 20 to 180 minutes at 150 to 220 ° C, more preferably in the range of 30 to 120 minutes at 160 to 200 ° C. It is a range. After forming the insulating layer, the metal foil is removed. The removal of the metal foil can be performed as it is when it can be physically peeled off, and can be removed by etching when it is difficult to peel off. Etching of the metal foil can be performed using an etching solution mainly composed of ferric chloride or copper chloride. Through the above steps, an insulating layer in which dents on the through holes are suppressed can be obtained. The recess of the insulating layer on the through hole is preferably 6 μm or less.

  Usually, a via hole is formed by drilling an insulating layer formed on a substrate. If necessary, through holes may be formed. Drilling can be performed by a known method such as drilling, laser, or plasma, or a combination of these methods if necessary. However, drilling by a laser such as a carbon dioxide laser or YAG laser is the most common method. .

  In order to form a circuit on the insulating layer, it is preferable to use a semi-additive method. In the semi-additive method, usually, after first roughening the surface of the insulating layer, a catalyst is applied, an electroless copper plating layer is formed, a pattern resist is applied on the copper plating layer, and a desired thickness is obtained. After forming the electrolytic copper plating layer, the pattern resist is peeled off, and the electroless copper plating layer is removed by flash etching to form a circuit. The roughening process on the surface of the insulating layer also serves as a desmear process for removing smear generated in the drilling process. The roughening treatment in the present invention is performed by a wet roughening method using an oxidizing agent. Examples of the oxidizing agent include permanganate (potassium permanganate, sodium permanganate, etc.), dichromate, ozone, hydrogen peroxide / sulfuric acid, nitric acid and the like. Preferably, an alkaline permanganate solution (eg, potassium permanganate, sodium hydroxide solution of sodium permanganate), which is an oxidizer widely used for roughening an insulating layer in the production of multilayer printed wiring boards by a built-up method. It is preferable to perform roughening using. As the catalyst imparted to the roughened surface, generally used palladium metal is preferable. Various electroless copper plating solutions are commercially available due to differences in bath constituents such as complexing agents and reducing agents, but are not particularly limited. The thickness of the electroless copper plating layer is usually 0.1 to 3 μm, preferably 0.3 to 2 μm.

  A method of performing electrolytic copper plating on the electroless copper plating surface can also be performed according to a known method, for example, using a commonly used copper sulfate plating bath. The thickness of the electrolytic copper plating layer is usually 3 to 40 μm, and preferably 5 to 35 μm. In addition, after forming the conductor layer, the peel strength of the conductor layer can be further improved and stabilized by annealing at 150 to 200 ° C. for 20 to 90 minutes.

  The multilayer printed wiring board obtained in this way has an insulating layer excellent in smoothness, in which dents on the through holes are suppressed.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The protective film of the Ajinomoto Fine Techno Co., Ltd. adhesive film (ABF-GX-13) with a resin composition layer thickness of 40 μm is peeled off, and the glossy surface of 35 μm electrolytic copper foil (JTC foil, manufactured by Nikko Materials Co., Ltd.) The resin composition layer was transferred by vacuum lamination to obtain an adhesive film using a copper foil as a support. Next, the PET film on the opposite side of the copper foil was peeled off through the resin composition layer, and laminated from both sides of a core substrate (FR4) having a through hole (through hole diameter 0.3 mm) and having a thickness of 0.3 mm. . Lamination is performed at a temperature of 100 ° C., a pressure of 7 kgf / cm ² (69 × 10 ⁴ N / m ² ), and a pressure of 5 mmHg (6.7 hPa) or less using a vacuum laminator with a heat press (MVLP-500, manufactured by Meiki Seisakusho). Pressurization was performed for 30 seconds, and then performed by applying pressure at a temperature of 100 ° C. and a pressure of 10 kgf / cm ² (98 × 10 ⁴ N / m ² ) for 90 seconds. Next, the resin composition layer is heated at 120 ° C. for 30 minutes, then thermally cured by heating at 180 ° C. for 30 minutes, cooled to room temperature, and then immersed in an etching solution made of ferric chloride (FeCl ₃ ) to obtain a copper foil. And a core substrate on which an insulating layer was formed was obtained.

    A core substrate on which an insulating layer was formed was obtained in the same manner as in Example 1 except that 20 μm rolled brass foil (manufactured by Nikko Metal Co., Ltd.) was used instead of the 35 μm electrolytic copper foil. Note that the metal foil used here can be physically peeled off, and peeled off by peeling off without being etched.

Manufacture of multilayer printed wiring boards (Part 1)
Through-hole filling and insulating layer formation were performed in the same manner as in Example 1 except that a circuit-formed substrate having a through-hole diameter of 0.3 mm and having a thickness of 0.3 mm was used. Next, via holes were formed in the insulating layer by a carbon dioxide laser. The roughening treatment of the insulating layer, which also serves as a desmear process, is performed using the oxidizing agent “Concentrate Compact CP” (alkaline permanganate solution) and the reducing agent “Reduction Solution Security” produced by Atotech Japan. solution Securiganth P-500) ". The insulating layer was surface treated with an oxidant solution at a temperature of 80 ° C. for 10 minutes. Next, neutralization was performed with a reducing agent solution at a temperature of 40 ° C. for 5 minutes. Next, after applying an electroless copper plating catalyst to the surface of the insulating layer, it was immersed in an electroless copper plating solution at 32 ° C. for 30 minutes to form an electroless copper plating film of 1.5 μm. This was dried at 150 ° C. for 30 minutes, washed with acid, and a phosphorous-containing copper plate was used as an anode, and electrolytic copper plating was performed at a cathode current density of 2.0 A / dm 2 for 12 minutes to form a copper plating film. Thereafter, an annealing treatment was further performed at 180 ° C. for 30 minutes. The obtained conductor layer had a conductor plating thickness of about 30 μm and a peel strength of 0.8 kgf / cm. The peel strength was measured according to JIS C6481.

Manufacture of multilayer printed wiring boards (Part 2)
A circuit-formed substrate having a through-hole diameter of 0.3 mm and a thickness of 0.3 mmt and a resin-coated copper foil obtained in Example 2 were used, and the removal of the copper foil was performed in the same manner as in Example 3 except that peeling was performed. A multilayer printed wiring board was obtained.

<Comparative Example 1>
A core substrate on which an insulating layer was formed was obtained in the same manner as in Example 1 except that an electrolytic copper foil (JTC foil, manufactured by Nikko Materials Co., Ltd.) having a thickness of 18 μm was used.

In addition, each performance evaluation was performed with the following method.
<Fillability of through holes>
A part of the evaluation substrate having the through hole was embedded with the embedding resin, and a cross section passing through the center of the through hole was visually observed by polishing and evaluated according to the following criteria.
○: The inside of the through hole is embedded with resin ×: A part of the through hole is not embedded with resin

<Through hole dent>
10 × 10 (= 100) through-holes in a lattice shape, a through-hole diameter of 300 μm, and through-hole pitches of 600, 900, and 1200 μm in thickness of 0.3 mmt evaluation board, adhesive film from both sides, or A metal foil with resin was laminated by lamination. Subsequently, after curing with a support film or metal foil, the support film or metal foil was removed by peeling or etching. With the resin exposed as described above, the through-hole dents of each through-hole pitch were measured in the X and Y directions and on the front and back surfaces thereof using a non-contact type surface roughness meter (WYKO NT3300 manufactured by Beeco Instruments). The dent was calculated with the average value. For the X and Y directions, the center of the through hole was the origin, the lamination direction was the Y direction, and the direction perpendicular thereto was the X direction. For the dent, the origin and the height difference located 300 μm outside in the X and Y directions were selected with N = 1 from each through hole pitch. Therefore, as a dent, it is an average value of 600, 900, and 1200 μm of through-hole pitches.

  As shown in Table 1, it can be seen that the comparative example has a large dent on the through hole, whereas Example 1 and Example 2 have the dent on the through hole suppressed.

Claims (6)

A method for producing a multilayer printed wiring board using an adhesive film in which a resin composition layer composed of a thermosetting resin composition is formed on a support, comprising at least the following steps 1) to 5 ):
1) A resin composition layer of an adhesive film having a resin composition layer thickness of 15 to 60 μm is brought into contact with a substrate having a through hole, and heated and pressurized under reduced pressure by a vacuum laminator to laminate the adhesive film. At the same time, the process of filling through holes,
2) a step of thermosetting the thermosetting resin composition in a state in which the resin composition is in contact with the glossy surface of the metal foil having a thickness of 20 μm or more to form an insulating layer;
3) A step of removing the metal foil after thermosetting,
4) a step of roughening the surface of the insulating layer with an oxidizing agent, and 5) a step of forming a conductor layer by plating on the surface of the roughened insulating layer,
A method for producing a multilayer printed wiring board, comprising: The method for producing a multilayer printed wiring board according to claim 1, wherein the adhesive film is an adhesive film in which a metal foil having a thickness of 20 μm or more is used as a support and a resin composition layer is formed on the glossy surface of the metal foil. The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the metal foil is selected from electrolytic copper foil, rolled copper foil or aluminum foil. The manufacturing method of the multilayer printed wiring board of any one of Claims 1-3 whose thickness of metal foil is 20 micrometers or more and 75 micrometers or less. The process of thermosetting the thermosetting resin composition is performed in two stages: a process of heat-treating the resin composition layer at a temperature of 70 ° C. to 140 ° C., and a process of thermosetting at a temperature higher than the temperature of the heat treatment. The manufacturing method of the multilayer printed wiring board of any one of Claims 1-4. The manufacturing method of the multilayer printed wiring board of any one of Claims 1-5 including the process of forming a via hole in an insulating layer after removing metal foil.