JP6343885B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board. Specifically, the present invention relates to a method for manufacturing a multilayer printed wiring board using a prepreg with a carrier.

  As a manufacturing technique of a multilayer printed wiring board, a manufacturing method by a build-up method in which insulating layers and conductor layers are alternately stacked is known. In the manufacturing method by the build-up method, the insulating layer is generally formed by thermosetting a resin composition. For example, a method of using an adhesive film in which a resin composition layer is formed on a carrier film and forming an insulating layer with a vacuum laminator is used. In recent years, a method for forming an insulating layer by a vacuum laminator using a prepreg with a carrier has been proposed in order to increase the mechanical strength of the insulating layer in accordance with the demand for a thinner multilayer printed wiring board (Patent Document 1). .

International Publication No. 2009/35014

  On the other hand, as the multilayer printed wiring board becomes thinner, it is more and more important to reduce the thermal expansion coefficient of the insulating layer in order to prevent cracks and the like due to the difference in thermal expansion from the conductor layer. Examples of means for reducing the thermal expansion coefficient of the insulating layer include increasing the content of the fiber base material and / or the inorganic filler in the prepreg used for forming the insulating layer. However, when a prepreg having a high fiber base material and / or inorganic filler content is used, it tends to be difficult to form an insulating layer having a smooth surface. For example, in the technique described in Patent Document 1, after laminating a prepreg with a carrier on an inner circuit board using a vacuum laminator, the surface of the laminated prepreg with a carrier is smoothed by hot pressing with a metal plate. However, when a prepreg having a high fiber base material and / or inorganic filler content is used, the prepreg is difficult to follow the surface irregularities (due to the presence or absence of circuit conductors) of the inner circuit board, and thus obtained. The surface of the insulating layer has undulations corresponding to the surface irregularities of the underlying inner circuit board, and it tends to be difficult to obtain an insulating layer having a smooth surface.

  For example, when hot pressing is performed under conditions that increase the fluidity of the resin, such as by setting the hot pressing temperature in the smoothing process high, the followability of the prepreg to the surface irregularities of the inner circuit board is improved, and the insulating layer The undulations on the surface can be reduced. However, in such a case, the balance of the thickness of the insulating layer is lost due to the seepage of the resin, etc., and there is a tendency that a large difference is generated in the thickness of the obtained insulating layer between the central portion of the substrate and the end portion of the substrate. The present inventors have found out.

  Even if the insulating layer is formed using a prepreg having a high total content of the fiber base material and the inorganic filler, the present invention is excellent in surface smoothness and is thick at the substrate center portion and the substrate end portion. It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board capable of realizing an insulating layer with a small difference in thickness and a good balance of layer thickness.

  As a result of intensive studies in view of the above problems, the present inventors have found that the total content of the fiber base material and the inorganic filler is a certain amount or more, and a prepreg having a specific melt viscosity is formed on the carrier film. When forming an insulating layer using a prepreg, the maximum cross-sectional height (Rt) of the carrier film surface of the prepreg with a carrier after the laminating process is maintained below a certain value, and the laminating temperature and smoothing of the laminating process are maintained. The inventors have found that the above problems can be solved by maintaining the difference in the hot press temperature of the process within a specific range, and have completed the present invention.

That is, the present invention includes the following contents.
[1] (I) A step of laminating a prepreg with a carrier having a prepreg formed on a carrier film on an inner layer circuit board so that the prepreg is bonded to the inner layer circuit board;
(II) A method for producing a multilayer printed wiring board comprising a step of smoothing a laminated prepreg with a carrier by hot pressing, and (III) a step of thermally curing the prepreg to form an insulating layer,
When the total mass of the prepreg is 100% by mass, the total mass of the fiber base material and the inorganic filler in the prepreg is 70% by mass or more,
The melt viscosity of the prepreg at the hot press temperature in step (II) is 300 to 10,000 poise,
The maximum cross-sectional height (Rt) of the carrier film surface of the prepreg with a carrier after step (I) is less than 5 μm, and the laminating temperature in step (I) is T1 (° C.), and the hot press temperature in step (II) And T2 (° C.), T1 and T2 satisfy the relationship of T2 ≦ T1 + 10. A method for producing a multilayer printed wiring board,
[2] The method according to [1], wherein T1 and T2 satisfy a relationship of T2 ≦ T1 + 5.
[3] The method according to [1] or [2], wherein the step (II) is performed twice or more.
[4] The method according to any one of [1] to [3], wherein the maximum cross-sectional height (Rt) of the insulating layer surface after step (III) is less than 3 μm.
[5] The method according to any one of [1] to [4], wherein the prepreg further contains an epoxy resin and a curing agent.
[6] The method according to any one of [1] to [5], wherein the prepreg is formed by impregnating a fiber base material with a resin composition containing an epoxy resin, a curing agent, and an inorganic filler.
[7] The method according to any one of [1] to [6], wherein the carrier film is peeled after the step (III).
[8] The method according to any one of [1] to [7], wherein in step (III), the prepreg is arranged in a vertical state in a heating oven and thermally cured to form an insulating layer.

  According to the method of the present invention, even when the insulating layer is formed using a prepreg having a high total content of the fiber base material and the inorganic filler, the surface smoothness is excellent, and the substrate center portion and the substrate end portion are formed. Thus, a multilayer printed wiring board having an insulating layer with a small thickness difference and a good balance of layer thickness can be manufactured.

  Before describing the manufacturing method of the multilayer printed wiring board of the present invention in detail, the “prepreg with carrier” used in the method of the present invention will be described.

<Prepreg with carrier>
In the method of the present invention, a prepreg with a carrier in which a prepreg is formed on a carrier film is used.

  Examples of the carrier film include a film made of a plastic material, a metal foil (copper foil, aluminum foil, etc.), and release paper. A film made of a plastic material is preferably used. Examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) and polyethylene naphthalate (hereinafter sometimes abbreviated as “PEN”), polycarbonate (hereinafter referred to as “PC”). And acrylic such as polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, and the like. Among these, polyethylene terephthalate and polyethylene naphthalate are preferable, and inexpensive polyethylene terephthalate is particularly preferable. In a preferred embodiment, the carrier film is a polyethylene terephthalate film.

  The carrier film may be subjected to mat treatment or corona treatment on the surface to be bonded to the prepreg.

  Moreover, as a carrier film, you may use the carrier film with a release layer which has a release layer in the surface joined to a prepreg. Examples of the release agent used for the release layer of the carrier film with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. .

  In the present invention, a commercially available product may be used as the carrier film with a release layer. Examples of commercially available products include “PET501010”, “SK-1”, “AL-5”, “AL-7” and the like manufactured by Lintec Corporation.

  Although the thickness of a carrier film is not specifically limited, The range of 10 micrometers-70 micrometers is preferable, The range of 20 micrometers-60 micrometers is more preferable, The range of 20 micrometers-50 micrometers is further more preferable. In addition, when a carrier film is a carrier film with a release layer, it is preferable that the thickness of the whole carrier film with a release layer is the said range.

  The prepreg is formed by impregnating a fiber base material with a resin composition.

  A fiber base material is not specifically limited, What is used normally as a base material for prepregs, such as a glass cloth, an aramid nonwoven fabric, and a liquid crystal polymer nonwoven fabric, can be used. When used for forming an insulating layer of a multilayer printed wiring board, a thin sheet-like fiber substrate having a thickness of 50 μm or less is preferably used, and particularly a sheet-like fiber substrate having a thickness of 10 μm to 40 μm is preferable. A sheet-like fiber substrate having a thickness of 10 μm to 30 μm is more preferable.

Specific examples of the glass cloth that can be used as the sheet-like fiber base material include “Style 1027MS” manufactured by Asahi Schwer Corporation (warp density 75/25 mm, weft density 75/25 mm, fabric weight 20 g / m ² , thickness 19 μm), “Style 1037MS” manufactured by Asahi Schubel Co., Ltd. (warp density 70/25 mm, weft density 73/25 mm, fabric weight 24 g / m ² , thickness 28 μm), manufactured by Arisawa Manufacturing Co., Ltd. 1078 "(warp density 54 / 25mm, weft density 54 / 25mm, fabric weight 48g / m ² , thickness 43µm)," 1037NS "(Awari Seisakusho, warp density 72 / 25mm, weft density 69) Book / 25mm, fabric weight 23g / m ² , thickness 21μm) “1027NS” manufactured by Arisawa Manufacturing Co., Ltd. (warp density 75 / 25mm, weft density 75/2 5 mm, fabric weight 19.5 g / m ² , thickness 16 μm), “1015NS” manufactured by Arisawa Manufacturing Co., Ltd. (warp density 95/25 mm, weft density 95/25 mm, fabric weight 17.5 g / m ² , 15 μm in thickness), “1000NS” manufactured by Arisawa Manufacturing Co., Ltd. (warp density 85/25 mm, weft density 85/25 mm, fabric weight 11 g / m ² , thickness 10 μm), and the like. Specific examples of the liquid crystal polymer nonwoven fabric include “Veculus” (weight per unit area: 6 to 15 g / m ² ) and “Vectran” manufactured by Kuraray Co., Ltd., which are produced by the melt blow method of an aromatic polyester nonwoven fabric.

  The resin composition used for the prepreg is not particularly limited as long as the cured product has sufficient hardness and insulation, and a conventionally known resin composition used for forming an insulating layer of a multilayer printed wiring board is used. It's okay.

  From the viewpoint of keeping the thermal expansion coefficient of the obtained insulating layer low, the resin composition used for the prepreg preferably contains an inorganic filler.

  Examples of inorganic fillers include silica, silicon nitride, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, and titanium. Examples thereof include barium oxide, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, and calcium zirconate. Among these, silica such as amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica is particularly suitable. Moreover, spherical silica is preferable as the silica. An inorganic filler may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of commercially available spherical fused silica include “SOC4”, “SOC2”, and “SOC1” manufactured by Admatechs.

  The average particle size of the inorganic filler is preferably 2 μm or less, more preferably 1 μm or less, still more preferably 0.8 μm or less, and even more preferably 0, from the viewpoint of obtaining an insulating layer with good insulation reliability and surface smoothness. .6 μm or less. On the other hand, from the viewpoint of improving the dispersibility of the inorganic filler, the average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, and further preferably 0.1 μm or more. The average particle diameter of the inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler can be prepared on a volume basis by a laser diffraction / scattering particle size distribution measuring apparatus, and the median diameter can be measured as the average particle diameter. As the measurement sample, an inorganic filler dispersed in water by ultrasonic waves can be preferably used. As a laser diffraction scattering type particle size distribution measuring apparatus, LA-950 manufactured by Horiba, Ltd. or the like can be used.

The content of the inorganic filler in the resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more, from the viewpoint of keeping the thermal expansion coefficient of the obtained insulating layer low. is there. Although the upper limit of content of the inorganic filler in a resin composition is not specifically limited, From a viewpoint of obtaining an insulating layer with favorable surface smoothness, Preferably it is 90 mass% or less, More preferably, it is 85 mass% or less.
In addition, in this invention, content of each component in a resin composition is a value when the non-volatile component in a resin composition is 100 mass%.

  Inorganic fillers are one type of epoxy silane coupling agent, aminosilane coupling agent, mercaptosilane coupling agent, silane coupling agent, organosilazane compound, titanate coupling agent, etc. for improving moisture resistance. It is preferable that the surface treatment agent is used. Among the surface treatment agents, aminosilane coupling agents are preferable because they are excellent in moisture resistance, dispersibility, cured product characteristics, and the like. The inorganic filler may be pretreated with a surface treatment agent before being mixed with the resin composition. Alternatively, the inorganic filler may be treated with the surface treatment agent by adding the inorganic filler and the surface treatment agent to the resin composition (that is, by an integral blend method). Commercially available surface treatment agents include “KBM403” (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. and “KBM803” (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., Shin-Etsu Chemical Co., Ltd. ) “KBM103” (phenyltrimethoxysilane), “SZ-31” (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

  The treatment amount of the surface treatment agent is preferably 0.01% by mass to 5% by mass, more preferably 0.1% by mass to 3% by mass, when the inorganic filler is 100% by mass.

  It is preferable that the resin composition used for the prepreg further contains an epoxy resin and a curing agent. Accordingly, in a preferred embodiment, the prepreg is formed by impregnating a fiber base material with a resin composition containing an epoxy resin, a curing agent and an inorganic filler.

-Epoxy resin-
Although it does not specifically limit as an epoxy resin, The epoxy resin which has a 2 or more epoxy group in 1 molecule is preferable. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin and bisphenol AF type epoxy resin and other bisphenol type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, Naphthol type epoxy resin, Naphthalene type epoxy resin, Naphthylene ether type epoxy resin, Glycidylamine type epoxy resin, Glycidyl ester type epoxy resin, Cresol novolac type epoxy resin, Biphenyl type epoxy resin, Anthracene type epoxy resin, Linear aliphatic epoxy Resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, Rimechiroru type epoxy resins, and halogenated epoxy resins. An epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these, from the viewpoint of heat resistance, insulation reliability, and fluidity, bisphenol type epoxy resins (preferably bisphenol A type epoxy resins and bisphenol F type epoxy resins), naphthol type epoxy resins, naphthalene type epoxy resins, biphenyl types Epoxy resins, naphthylene ether type epoxy resins, glycidyl ester type epoxy resins, anthracene type epoxy resins, and epoxy resins having a butadiene structure are preferred. In particular, the epoxy resin is a group consisting of bisphenol type epoxy resin (preferably bisphenol A type epoxy resin, bisphenol F type epoxy resin), naphthol type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin and naphthylene ether type epoxy resin. It is preferable that 1 or more types selected from are included. Specifically, for example, bisphenol A type epoxy resin (“jER828EL”, “YL980” manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resin (“jER806H”, “YL983U” manufactured by Mitsubishi Chemical Corporation), naphthalene, etc. Type bifunctional epoxy resin (“HP4032”, “HP4032D”, “HP4032SS”, “EXA4032SS”) manufactured by DIC Corporation, naphthalene type tetrafunctional epoxy resin (“HP4700”, “HP4710” manufactured by DIC Corporation), naphthol Type epoxy resin (“ESN-475V” manufactured by Nippon Steel Chemical Co., Ltd.), epoxy resin having a butadiene structure (“PB-3600” manufactured by Daicel Chemical Industries, Ltd.), biphenyl type epoxy resin (Nippon Kayaku Co., Ltd.) ) "NC3000H", "NC3000L", "NC3100", Mitsubishi "YX4000", "YX4000H", "YX4000HK", "YL6121"), anthracene type epoxy resin ("YX8800" manufactured by Mitsubishi Chemical Corporation), naphthylene ether type epoxy resin (DIC Corporation) “EXA-7310”, “EXA-7311”, “EXA-7311L”, “EXA-7311G3”, “EXA-7311G4”), glycidyl ester type epoxy resin (“EX711”, “EX721” manufactured by Nagase ChemteX Corporation) And "R540" manufactured by Printec Co., Ltd.).

  The epoxy resin preferably contains an epoxy resin having two or more epoxy groups in one molecule. When the nonvolatile component of the epoxy resin is 100% by mass, at least 50% by mass is preferably an epoxy resin having two or more epoxy groups in one molecule.

  From the viewpoint of improving the followability of the prepreg to the surface irregularities of the inner layer circuit board, the epoxy resin preferably contains a liquid epoxy resin (hereinafter also referred to as “liquid epoxy resin”) at a temperature of 20 ° C. From the viewpoint of improving the followability of the prepreg to the surface irregularities of the inner circuit board and improving the cured physical properties of the insulating layer formed by thermosetting the prepreg, the epoxy resin is solid at a temperature of 20 ° C. with a liquid epoxy resin. It is preferable that it contains an epoxy resin (hereinafter also referred to as “solid epoxy resin”). The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule, and more preferably an aromatic liquid epoxy resin having two or more epoxy groups in one molecule. The solid epoxy resin is preferably a solid epoxy resin having 3 or more epoxy groups in one molecule, and more preferably an aromatic solid epoxy resin having 3 or more epoxy groups in one molecule. In the present invention, the aromatic epoxy resin means an epoxy resin having an aromatic ring in the molecule.

  Examples of the liquid epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, glycidyl ester type epoxy resin, naphthalene type epoxy resin, and the like. Bisphenol A type epoxy resin, bisphenol F type epoxy resin Naphthalene type epoxy resin is preferred. A liquid epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type. Solid epoxy resins include naphthalene type tetrafunctional epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, biphenyl type epoxy resin, naphthylene ether Naphthalene type tetrafunctional epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, and naphthylene ether type epoxy resin are more preferable. A solid epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the case where a liquid epoxy resin and a solid epoxy resin are used in combination as an epoxy resin, from the viewpoint of improving the cured material properties of the resulting insulating layer, their blending ratio (liquid epoxy resin: solid epoxy resin) is a mass ratio, The range of 1: 0.1 to 1: 8 is preferable, the range of 1: 0.3 to 1: 7 is more preferable, the range of 1: 0.6 to 1: 6 is still more preferable, and 1: 0.9 to A range of 1: 5.5 is even more preferred.

  The epoxy equivalent of the epoxy resin is preferably 50 to 3000, more preferably 80 to 2000, and still more preferably 110 to 1000. The epoxy equivalent can be measured according to JIS K7236, and is the mass of a resin containing 1 equivalent of an epoxy group.

  The content of the epoxy resin in the resin composition is preferably 3% by mass to 40% by mass, more preferably 5% by mass to 35% by mass, and still more preferably 10% by mass to 30% by mass. From the viewpoint of improving the followability of the prepreg to the surface irregularities of the inner layer circuit board, the content of the liquid epoxy resin in the resin composition is preferably 1% by mass to 35% by mass, and more preferably 3% by mass to 30% by mass. Preferably, 6 mass%-25 mass% are still more preferable.

-Curing agent-
The curing agent is not particularly limited as long as it has a function of curing an epoxy resin. For example, a phenolic curing agent, an active ester curing agent, a cyanate ester curing agent, a benzoxazine curing agent, and an acid anhydride curing. Agents. A hardening | curing agent may be used individually by 1 type, and may be used in combination of 2 or more type. In a preferred embodiment, the curing agent is at least one selected from the group consisting of a phenolic curing agent, an active ester curing agent, and a cyanate ester curing agent.

  Although it does not restrict | limit especially as a phenol type hardening | curing agent, A biphenyl type hardening | curing agent, a naphthalene type hardening | curing agent, a phenol novolak type hardening | curing agent, a naphthylene ether type hardening | curing agent, and a triazine skeleton containing phenol type hardening | curing agent are preferable. A phenol type hardening | curing agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Commercially available phenolic curing agents include MEH-7700, MEH-7810, MEH-7785 (Maywa Kasei Co., Ltd.) as biphenyl type curing agents, NHN, CBN, GPH (Nippon Kayaku (manufactured by Meiwa Kasei Co., Ltd.)). SN170, SN180, SN190, SN475, SN485, SN495, SN375, SN395 (manufactured by Nippon Steel Chemical Co., Ltd.), EXB9500, HPC9500 (manufactured by DIC Corporation), TD2090 (phenol novolac type curing agent) DIC Corporation), EXB-6000 (manufactured by DIC Corporation) as a naphthylene ether type curing agent, LA3018, LA7052, LA7054, LA1356 (manufactured by DIC Corporation), etc. as triazine skeleton-containing phenolic curing agents. It is done. Of these, naphthalene type curing agents and triazine skeleton-containing phenolic curing agents are preferred.

  Although there is no restriction | limiting in particular as an active ester type hardening | curing agent, Generally ester groups with high reaction activity, such as phenol ester, thiophenol ester, N-hydroxyamine ester, ester of heterocyclic hydroxy compound, are in 1 molecule. A compound having two or more in the above is preferably used. The active ester curing agent is preferably obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferable, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferable. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of the phenol compound or naphthol compound include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m- Cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, Benzenetriol, dicyclopentadiene type diphenol, phenol novolac and the like.

  The active ester curing agent includes an active ester curing agent having a dicyclopentadiene type diphenol structure, an active ester curing agent having a naphthalene structure, an active ester curing agent which is an acetylated product of phenol novolac, and a benzoyl of phenol novolac. An active ester type curing agent that is a compound is preferable, and among them, from the viewpoint of reducing the melt viscosity of the prepreg and improving the followability to the surface irregularities of the inner circuit board, the active ester type containing a dicyclopentadiene type diphenol structure A curing agent is more preferable. In the present invention, the “dicyclopentadiene type diphenol structure” represents a divalent structural unit composed of phenylene-dicyclopentalene-phenylene. An active ester hardening agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Commercially available active ester curing agents include EXB9451, EXB9460, EXB9460S-65T, HPC8000-65T (manufactured by DIC Corporation), and acetylated phenol novolac as active ester curing agents containing a dicyclopentadiene type diphenol structure. DC808 (manufactured by Mitsubishi Chemical Corporation) as an active ester-based curing agent, YLH1026 (manufactured by Mitsubishi Chemical Corporation), YLH1030 (manufactured by Mitsubishi Chemical Corporation) as active ester-based curing agents which are benzoylated phenol novolacs YLH1048 (manufactured by Mitsubishi Chemical Corporation) and the like.

  The cyanate ester-based curing agent is not particularly limited. For example, novolak type (phenol novolac type, alkylphenol novolak type, etc.) cyanate ester-based curing agent, dicyclopentadiene type cyanate ester-based curing agent, bisphenol type (bisphenol A type) , Bisphenol F type, bisphenol S type, etc.) cyanate ester-based curing agents, and prepolymers in which these are partially triazines. Although the weight average molecular weight of a cyanate ester hardening | curing agent is not specifically limited, Preferably it is 500-4500, More preferably, it is 600-3000.

  Specific examples of the cyanate ester curing agent 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 resole novolac, dicyclopentadiene structure-containing phenol resins, prepolymers in which these cyanate resins are partially triazines, etc. Cyanate ester-based curing agents are used alone. Or two or more kinds may be used in combination.

  Commercial products of cyanate ester-based curing agents include phenol novolac polyfunctional cyanate ester resin PT30 (manufactured by Lonza Japan Co., Ltd.), a prepolymer in which a part or all of bisphenol A dicyanate is triazine and becomes a trimer. As examples, BA230 (manufactured by Lonza Japan Co., Ltd.) and dicyclopentadiene structure-containing cyanate ester resins include DT-4000 and DT-7000 (manufactured by Lonza Japan Co., Ltd.).

  Specific examples of the benzoxazine-based curing agent include “HFB2006M” manufactured by Showa Polymer Co., Ltd., “Pd” and “Fa” manufactured by Shikoku Kasei Kogyo Co., Ltd. A benzoxazine type hardening | curing agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride. , Trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride Acid, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetra Carboxylic dianhydride, 1,3,3a, 4,5,9b-hex Hydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione, ethylene glycol bis (anhydrotrimellitate), styrene and maleic acid Examples thereof include polymer-type acid anhydrides such as copolymerized styrene / maleic acid resins. An acid anhydride type hardening | curing agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The mixing ratio of the epoxy resin and the curing agent is preferably such that the number of reactive groups of the curing agent is in the range of 0.3 to 2.0 when the number of epoxy groups of the epoxy resin is 1, The ratio which becomes a range is more preferable, and the ratio which becomes the range of 0.4-1.1 is further more preferable. In addition, the number of epoxy groups of an epoxy resin is the value which totaled the value which remove | divided the solid content mass of each epoxy resin contained in a resin composition by epoxy equivalent about all the epoxy resins. Further, the number of reactive groups of the curing agent is a value obtained by adding the values obtained by dividing the solid content mass of each curing agent contained in the resin composition by the reactive group equivalent for all the curing agents.

  The resin composition used for the prepreg may further contain additives such as a thermoplastic resin, a curing accelerator, a flame retardant, and rubber particles as necessary.

-Thermoplastic resin-
The resin composition used for the prepreg may contain a thermoplastic resin from the viewpoint that after the prepreg is cured, the surface can be roughened to form an insulating layer having an appropriate roughened surface. Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyimide resin, polyamideimide resin, polyethersulfone resin, and polysulfone resin. A thermoplastic resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  The weight average molecular weight in terms of polystyrene of the thermoplastic resin is preferably in the range of 8,000 to 70,000, more preferably in the range of 10,000 to 60,000, still more preferably in the range of 15,000 to 60,000, and 20 More preferably, the range is from 6,000 to 60,000. The weight average molecular weight in terms of polystyrene of the thermoplastic resin is measured by a gel permeation chromatography (GPC) method. Specifically, the polystyrene-reduced weight average molecular weight of the thermoplastic resin is LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, and Shodex K-800P / K- manufactured by Showa Denko KK as a column. 804L / K-804L can be measured at a column temperature of 40 ° C. using chloroform or the like as a mobile phase, and can be calculated using a standard polystyrene calibration curve.

  Examples of the phenoxy resin include bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene Examples thereof include phenoxy resins having a skeleton and one or more skeletons selected from the group consisting of a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. A phenoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type. Specific examples of the phenoxy resin include “1256” and “4250” (both bisphenol A skeleton-containing phenoxy resin), “YX8100” (bisphenol S skeleton-containing phenoxy resin), and “YX6954” (manufactured by Mitsubishi Chemical Corporation). In addition, “FX280” and “FX293” manufactured by Toto Kasei Co., Ltd., “YL7553”, “YL6794”, “YL7213” manufactured by Mitsubishi Chemical Corporation, YL7290 "," YL7482 ", etc. are mentioned.

  Specific examples of the polyvinyl acetal resin include: Electric Butyral 4000-2, 5000-A, 6000-C, 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd., S-Lec BH Series, BX Series manufactured by Sekisui Chemical Co., Ltd. KS series, BL series, BM series, etc. are mentioned.

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

  Specific examples of the polyamide-imide resin include “Bilomax HR11NN” and “Bilomax HR16NN” manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin also include modified polyamideimides such as polysiloxane skeleton-containing polyamideimides “KS9100” and “KS9300” manufactured by Hitachi Chemical Co., Ltd.

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

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

  The content of the thermoplastic resin in the resin composition is preferably 0.1% by mass to 60% by mass, more preferably 0.1% by mass to 50% by mass, and further preferably 0.5% by mass to 30% by mass. Still more preferably, it is 0.5 mass%-10 mass%.

-Curing accelerator-
The resin composition used for the prepreg may contain a curing accelerator from the viewpoint of allowing the thermosetting of the prepreg to proceed smoothly. Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and guanidine-based curing accelerators. A hardening accelerator may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the curing accelerator in the resin composition is preferably 0.01% by mass to 3% by mass, more preferably 0.01% by mass when the total of the nonvolatile components of the epoxy resin and the curing agent is 100% by mass. % To 2% by mass, more preferably 0.01% to 1% by mass.

-Flame retardant-
The resin composition used for the prepreg may contain a flame retardant from the viewpoint of improving flame retardancy. Examples of the flame retardant include an organic phosphorus flame retardant, an organic nitrogen-containing phosphorus compound, a nitrogen compound, a silicone flame retardant, and a metal hydroxide. Examples of organic phosphorus flame retardants include phenanthrene-type phosphorus compounds such as HCA, HCA-HQ, and HCA-NQ manufactured by Sanko Co., Ltd., phosphorus-containing benzoxazine compounds such as HFB-2006M manufactured by Showa Polymer Co., Ltd., and Ajinomoto Co., Inc. Reefos 30, 50, 65, 90, 110, Fine Techno Co., TPP, RPD, BAPP, CPD, TCP, TXP, TBP, TOP, KP140, TIBP, TPPO, PPQ, manufactured by Hokuko Chemical Co., Ltd. Examples include phosphate ester compounds such as OP930 manufactured by Clariant Co., Ltd. and PX200 manufactured by Daihachi Chemical Co., Ltd. Examples of organic nitrogen-containing phosphorus compounds include phosphoric ester amide compounds such as SP670 and SP703 manufactured by Shikoku Kasei Kogyo Co., Ltd., SPB100 and SPE100 manufactured by Otsuka Chemical Co., Ltd., and FP-series manufactured by Fushimi Pharmaceutical Co., Ltd. Phosphazene compounds such as As the metal hydroxide, magnesium hydroxide such as UD65, UD650, UD653 manufactured by Ube Materials Co., Ltd., B-30, B-325, B-315, B-308 manufactured by Sakai Kogyo Co., Ltd. Examples thereof include aluminum hydroxide such as B-303 and UFH-20. A flame retardant may be used individually by 1 type and may be used in combination of 2 or more type. The content of the flame retardant in the resin composition is not particularly limited, but is preferably 0.5% by mass to 10% by mass, and more preferably 1% by mass to 9% by mass.

-Rubber particles-
The resin composition used for the prepreg may contain rubber particles from the viewpoint that after the prepreg is cured, the surface is roughened to form an insulating layer having an appropriate roughened surface. As the rubber particles, for example, those that do not dissolve in an organic solvent described later and are incompatible with the above-described epoxy resin, curing agent, thermoplastic resin, and the like are used. Such rubber particles are generally prepared by increasing the molecular weight of the rubber component to a level at which it does not dissolve in an organic solvent or resin and making it into particles.

  Examples of the rubber particles include core-shell type rubber particles, cross-linked acrylonitrile butadiene rubber particles, cross-linked styrene butadiene rubber particles, and acrylic rubber particles. The core-shell type rubber particles are rubber particles having a core layer and a shell layer. For example, a two-layer structure in which an outer shell layer is made of a glassy polymer and an inner core layer is made of a rubbery polymer, or Examples include a three-layer structure in which the outer shell layer is made of a glassy polymer, the intermediate layer is made of a rubbery polymer, and the core layer is made of a glassy polymer. The glassy polymer layer is made of, for example, methyl methacrylate polymer, and the rubbery polymer layer is made of, for example, butyl acrylate polymer (butyl rubber). Specific examples of the core-shell type rubber particles include Staphyloid AC3832, AC3816N, IM-401-modified 1, IM-401-modified 7-17 (manufactured by Ganz Kasei Co., Ltd.), Metabrene KW-4426 (manufactured by Mitsubishi Rayon Co., Ltd.). Is mentioned. Specific examples of the crosslinked acrylonitrile butadiene rubber (NBR) particles include XER-91 (average particle size: 0.5 μm, manufactured by JSR Corporation). Specific examples of the crosslinked styrene butadiene rubber (SBR) particles include XSK-500 (average particle size 0.5 μm, manufactured by JSR Corporation). Specific examples of the acrylic rubber particles include Methbrene W300A (average particle size 0.1 μm) and W450A (average particle size 0.2 μm) (manufactured by Mitsubishi Rayon Co., Ltd.). A rubber particle may be used individually by 1 type and may be used in combination of 2 or more type.

  The average particle size of the rubber particles is preferably in the range of 0.005 μm to 1 μm, more preferably in the range of 0.2 μm to 0.6 μm. The average particle diameter of the rubber particles can be measured using a dynamic light scattering method. For example, rubber particles are uniformly dispersed in an appropriate organic solvent by ultrasonic waves, etc., and a particle size distribution of rubber particles is created on a mass basis using a concentrated particle size analyzer (FPAR-1000; manufactured by Otsuka Electronics Co., Ltd.). And it can measure by making the median diameter into an average particle diameter. The content of the rubber particles in the resin composition is preferably 1% by mass to 10% by mass, and more preferably 2% by mass to 5% by mass.

-Other components-
The resin composition used for the prepreg may contain other components as necessary. Other components include, for example, thermosetting resins such as vinyl benzyl compounds, acrylic compounds, maleimide compounds, and blocked isocyanate compounds, organic fillers such as silicon powder, nylon powder, and fluorine powder, and thickeners such as olben and benton. Agents, silicone-based, fluorine-based, polymer-based antifoaming or leveling agents, imidazole-based coupling agents, thiazole-based coupling agents, triazole-based coupling agents, silane-based coupling agents, and the like, phthalocyanines -Coloring agents such as blue, phthalocyanine green, iodin green, disazo yellow, carbon black and the like can be mentioned.

  The resin composition used for the prepreg is prepared by appropriately mixing the above-mentioned components and, if necessary, kneading means (three rolls, ball mill, bead mill, sand mill, etc.) or stirring means (super mixer, planetary mixer, etc.). It can be produced by kneading or mixing.

The production method of the prepreg with a carrier is not particularly limited, and examples thereof include a solvent method and a hot melt method, and one or more methods selected from the group consisting of the following methods (i) to (iv) are preferable. .
(I): A method in which a resin composition is once coated on a carrier film without dissolving the resin composition in an organic solvent, and is laminated on a fiber substrate. (Ii): The resin composition is made into fibers by a die coater or the like. A method of forming a prepreg by coating directly on a substrate, and then laminating the prepreg on a carrier film (iii): preparing a resin varnish in which the resin composition is dissolved in an organic solvent, and using the fiber substrate as a resin varnish Method of laminating, impregnating and drying to form prepreg, and then laminating prepreg on carrier film (iv): Resin varnish is directly coated on carrier film using die coater etc. to form resin composition layer And laminating the resin composition layer from both sides of the fiber substrate

  When the resin varnish is used, examples of the organic solvent include ketones such as acetone, methyl ethyl ketone and cyclohexanone, acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate, cellosolve and Examples thereof include carbitols such as butyl carbitol, aromatic hydrocarbons such as toluene and xylene, amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. An organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The resin varnish may be dried by a known drying method such as heating or hot air blowing. Although drying conditions are not specifically limited, In the manufacturing method of the multilayer printed wiring board mentioned later, a prepreg needs to have fluidity | liquidity (flow property) and adhesiveness. Therefore, when drying the resin varnish, it is important not to allow the resin composition to cure as much as possible. On the other hand, if a large amount of organic solvent remains in the prepreg, it will cause swelling after curing. Therefore, it is dried so that the amount of residual organic solvent in the prepreg is usually 5% by mass or less, preferably 2% by mass or less. Depending on the boiling point of the organic solvent in the resin varnish, for example, when using a varnish containing 30% by mass to 60% by mass of the organic solvent, it is usually preferable to dry at 80 ° C. to 180 ° C. for 3 minutes to 20 minutes. .

  As described above, the prepreg with a carrier used in the method of the present invention is formed by providing a prepreg on a carrier film. Therefore, in one embodiment, the prepreg with a carrier includes a carrier film and a prepreg bonded to the carrier film. In the prepreg with a carrier, an ultrathin resin layer may be included between the carrier film and the prepreg. Therefore, in another embodiment, the prepreg with a carrier includes a carrier film, an ultrathin resin layer bonded to the carrier film, and a prepreg bonded to the ultrathin resin layer. Here, the ultrathin resin layer refers to a resin layer (insulating layer) having a thickness of 1 to 10 μm and containing no fiber substrate.

  In the prepreg with a carrier, a protective film according to the carrier film may be further laminated on the surface of the prepreg that is not joined to the carrier film (that is, the surface opposite to the carrier film). By laminating the protective film, it is possible to prevent dust from adhering to the surface of the prepreg and scratches. When manufacturing a multilayer printed wiring board, it can be used by removing the protective film.

  In the prepreg with a carrier, the thickness of the prepreg is preferably 100 μm or less, more preferably 90 μm or less, still more preferably 80 μm or less, from the viewpoint of reducing the thickness of the insulating layer to reduce the thickness of the multilayer printed wiring board. More preferably, it is 70 micrometers or less, Most preferably, it is 60 micrometers or less or 50 micrometers or less. The lower limit of the thickness of the prepreg is preferably 20 μm or more, more preferably 30 μm or more, from the viewpoint of ensuring the mechanical strength desired as the prepreg.

  In the prepreg with a carrier, when the total mass of the prepreg is 100% by mass, the total mass of the fiber base material and the inorganic filler in the prepreg is 70% by mass or more. As described above, when the total content of the fiber base material and the inorganic filler in the prepreg is high, the thermal expansion coefficient of the obtained insulating layer can be kept low, but it is difficult to obtain an insulating layer having a smooth surface. The present inventors have found that. Although details will be described later, according to the method for producing a multilayer printed wiring board of the present invention, even when using a prepreg having a high total content of 70% by mass or more of the fiber base material and the inorganic filler, The smooth insulating layer can be advantageously realized.

  In the prepreg with a carrier, the content ratio of the fiber base material and the inorganic filler in the prepreg (the mass ratio of the fiber base material / inorganic filler) is 0.2 to from the viewpoint of achieving mechanical strength and thinning of the prepreg. It is preferable to control to 2.5. Furthermore, from the viewpoint that the thermal expansion coefficient of the insulating layer can be efficiently reduced by filling the gaps in the fiber base material with many inorganic fillers, the content ratio is more preferably 2.3 or less, and still more preferably. Is 2.1 or less, even more preferably 1.9 or less, particularly preferably 1.7 or less or 1.5 or less. Further, from the viewpoint of preventing an increase in melt viscosity of the resin composition and allowing the inorganic filler to efficiently enter the gaps in the fiber base material, the content ratio is more preferably 0.25 or more, and even more preferably 0. .3 or more, and even more preferably 0.35 or more.

  In the prepreg with a carrier used in the method of the present invention, the prepreg has a melt viscosity of 300 to 10,000 poise at a temperature T2 described later (that is, the hot press temperature in step (II) in the method for producing a multilayer printed wiring board of the present invention). Have By setting the melt viscosity of the prepreg at the temperature T2 in such a range, an insulating layer having a smooth surface and having a small thickness difference between the substrate center and the substrate end and a good balance of the layer thickness is advantageous. Can be realized. The melt viscosity of the prepreg at the temperature T2 is preferably 600 poise or higher, more preferably 900 poise or higher, more preferably 1000 poise or higher, from the viewpoint of obtaining an insulating layer having a smaller difference in thickness between the substrate center and the substrate end. More preferably, it is 1200 poise or more, particularly preferably 1400 poise or more, 1600 poise or more, 1800 poise or more, 2000 poise or more, 2200 poise or more, 2400 poise or more, 2800 poise or more, or 3000 poise or more. From the viewpoint of obtaining an insulating layer having a smoother surface, and from the viewpoint of preventing air entrainment and suppressing void generation, the melt viscosity of the prepreg at temperature T2 is preferably 9000 poise or less, more preferably 8000 poise or less, Preferably it is 7000 poise or less, even more preferably 6000 poise or less, particularly preferably 5000 poise or less. The melt viscosity of the prepreg at the temperature T2 can be obtained by performing dynamic viscoelasticity measurement. For example, the melt viscosity of the prepreg at temperature T2 is measured by dynamic viscoelasticity measurement under the conditions of a measurement start temperature of 60 ° C., a heating rate of 5 ° C./min, a frequency of 1 Hz, a strain of 1 deg, and a measurement temperature interval of 2.5 ° C. It can be obtained by reading the melt viscosity at a temperature T2 (° C.) from a plot of temperature and melt viscosity. Examples of the dynamic viscoelasticity measuring apparatus include “Rheosol-G3000” manufactured by UBM Co., Ltd.

  Hereinafter, the present invention will be described in detail.

[Manufacturing method of multilayer printed wiring board]
The method for producing a multilayer printed wiring board of the present invention comprises: (I) a step of laminating a prepreg with a carrier having a prepreg formed on a carrier film on an inner layer circuit board so that the prepreg is bonded to the inner layer circuit board; ) Including a step of smoothing the laminated prepreg with a carrier by hot pressing, and (III) a step of thermally curing the prepreg to form an insulating layer, and when the total mass of the prepreg is 100% by mass, The total mass of the fiber base material and the inorganic filler is 70% by mass or more, the melt viscosity of the prepreg at the hot pressing temperature in the step (II) is 300 to 10,000 poise, and the prepreg with a carrier after the step (I) The maximum cross-sectional height (Rt) of the carrier film surface is less than 5 μm, and the laminating temperature in step (I) is T (° C.), when the hot press temperature in step (II) and T2 (° C.), characterized in that the T1 and T2 satisfy the relationship T2 ≦ T1 + 10.

<Process (I)>
In step (I), a carrier-prepared prepreg having a prepreg formed on a carrier film is laminated to the inner layer circuit board so that the prepreg is bonded to the inner layer circuit board.

  The prepreg with a carrier is as described above. In the prepreg used in the method of the present invention, when the total mass of the prepreg is 100% by mass, the total mass of the fiber base material and the inorganic filler in the prepreg is 70% by mass or more, and the hot press in the step (II) The melt viscosity at a temperature is 300 to 10,000 poise.

  In the method for producing a multilayer printed wiring board of the present invention, the “inner circuit board” means one or both sides of a substrate such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate. An intermediate product having a conductor layer (circuit conductor) patterned on the substrate and having an insulating layer and a conductor layer further formed when a multilayer printed wiring board is manufactured.

  The thickness of the circuit conductor patterned on one or both sides of the substrate is not particularly limited, but is preferably 70 μm or less, more preferably 60 μm or less, and still more preferably from the viewpoint of thinning the multilayer printed wiring board. It is 50 μm or less, more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit of the thickness of the circuit conductor is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more.

  The line / space ratio of the circuit conductor patterned on one or both sides of the substrate is not particularly limited, but from the viewpoint of obtaining an insulating layer excellent in surface smoothness by suppressing the undulation of the insulating layer surface, usually 900/900 μm or less, Preferably it is 700/700 micrometers or less, More preferably, it is 500/500 micrometers or less, More preferably, it is 300/300 micrometers or less, More preferably, it is 200/200 micrometers or less. The lower limit of the line / space ratio of the circuit conductor is not particularly limited, but is preferably 1/1 μm or more in order to satisfactorily embed the prepreg between the spaces.

  Further, the circuit conductor occupation ratio ((area of the circuit conductor portion) / (surface area of the inner layer circuit board) × 100 [%]) on the surface of the inner layer circuit board may be determined according to desired characteristics. The circuit conductor occupation ratio is also referred to as “remaining copper ratio” when the circuit conductor is formed of copper. The circuit conductor occupation ratio may be distributed over the surface of the inner layer circuit board. For example, an inner layer circuit board in which a region having a first circuit conductor occupation ratio and a region having a second circuit conductor occupation ratio are formed may be used. As a general tendency, the lower the circuit conductor occupation ratio, the thinner the insulating layer formed on the inner circuit board is on the circuit conductor. In particular, this tendency becomes more prominent as the thickness of the prepreg used to form the insulating layer is thinner. Here, “the thickness of the insulating layer on the circuit conductor” means the thickness of the insulating layer immediately above the circuit conductor. In the present invention, since an insulating layer having a small thickness difference can be realized between the substrate end and the substrate central portion, even when a thin prepreg is used, the entire substrate is expected. An insulating layer that exhibits insulation reliability can be realized. In the present invention, the thickness of the insulating layer at the edge of the substrate refers to the thickness of the insulating layer on the circuit conductor at the edge of the substrate, and the thickness of the insulating layer at the center of the substrate refers to the thickness of the insulating layer at the center of the substrate. The thickness on a circuit conductor.

  The laminating process in step (I) can be performed, for example, by thermocompression bonding the prepreg with a carrier to the inner layer circuit board so that the prepreg is bonded to the inner layer circuit board under reduced pressure conditions. Examples of a member (hereinafter, also referred to as “heat-bonding member”) for heat-pressing the carrier-prepared prepreg to the inner layer circuit board include a heated metal plate (SUS end plate, etc.) or a metal roll (SUS roll). . It is preferable that the thermocompression bonding member is not pressed directly onto the prepreg with a carrier, but is pressed through an elastic material such as heat-resistant rubber so that the prepreg sufficiently follows the surface irregularities of the inner layer circuit board. The prepreg with a carrier may be laminated on one side of the inner layer circuit board, or may be laminated on both sides of the inner layer circuit board.

  The heating temperature during the laminating process (hereinafter also referred to as “laminating temperature”) is preferably 60 ° C. or higher from the viewpoint of improving the followability of the prepreg to the surface irregularities of the inner circuit board and obtaining a smooth insulating layer. More preferably, it is 70 ° C. or higher, more preferably 80 ° C. or higher, even more preferably 90 ° C. or higher, particularly preferably 100 ° C. or higher, 110 ° C. or higher, or 120 ° C. or higher. Further, from the viewpoint of preventing the resin from exuding and obtaining an insulating layer having a good balance of layer thickness, the upper limit of the lamination temperature is preferably 160 ° C. or less, more preferably 150 ° C. or less, further preferably 140 ° C. or less, More preferably, it is 130 degrees C or less. Note that the lamination temperature refers to the surface temperature of the thermocompression bonding member, and in the case of pressing through an elastic material such as heat-resistant rubber, it refers to the temperature of the surface of the elastic material joined to the prepreg with a carrier.

  The pressure during the laminating process is preferably 0.098 MPa or more, more preferably 0.29 MPa or more, from the viewpoint of improving the followability of the prepreg to the surface irregularities of the inner circuit board and obtaining a smooth insulating layer. Preferably it is 0.40 MPa or more, and more preferably 0.49 MPa or more. In addition, from the viewpoint of preventing the resin from bleeding and obtaining an insulating layer having a good balance of layer thickness, the upper limit of the pressure is preferably 1.77 MPa or less, more preferably 1.47 MPa or less, and even more preferably 1.10 MPa. It is as follows.

  The pressure-bonding time at the time of laminating is preferably 10 seconds or longer, more preferably 15 seconds or longer, more preferably 20 seconds or longer, and even more preferably 25 seconds from the viewpoint of sufficiently following the prepreg on the surface irregularities of the inner layer circuit board. That's it. From the viewpoint of productivity, the upper limit of the pressure bonding time is preferably 300 seconds or less, more preferably 250 seconds or less, still more preferably 200 seconds or less, even more preferably 150 seconds or less, particularly preferably 100 seconds or less or 50 Less than a second.

  The degree of vacuum at the time of laminating is preferably 0.01 hPa or more, more preferably 0.05 hPa or more, and further preferably 0.1 hPa or more, from the viewpoint that the laminating process can be efficiently performed. From the viewpoint of obtaining an insulating layer having a smooth surface and preventing the entry of air into the insulating layer and suppressing the generation of voids, the upper limit of the degree of vacuum is preferably 27 hPa or less, more preferably 22 hPa or less, and still more preferably Is 17 hPa or less, more preferably 13 hPa or less. From the viewpoint of suppressing the generation of voids, the evacuation time is preferably 20 seconds or longer, more preferably 30 seconds or longer, 40 seconds or longer, 50 seconds or longer, or 60 seconds or longer.

  By the step (I), a laminate including an inner layer circuit board and a prepreg with a carrier provided so that the prepreg is bonded to the inner layer circuit board is obtained. In the present invention, in order to obtain an insulating layer having excellent surface smoothness, the step (I) is carried out so that the maximum cross-sectional height (Rt) of the carrier film surface of the carrier-prepared prepreg after step (I) is less than 5 μm. ) Is important. For example, depending on the composition and type of the prepreg and carrier film to be used, the laminating temperature, pressure pressure, pressure bonding time, vacuum degree and other laminating conditions are manipulated to obtain the maximum cross-sectional height (Rt) of the carrier film surface. Step (I) is carried out so that is less than 5 μm.

From the viewpoint of obtaining an insulating layer having excellent surface smoothness, the maximum cross-sectional height (Rt) of the carrier film surface of the carrier-attached prepreg after step (I) is preferably 4.5 μm or less, more preferably 4 μm or less, Preferably, it is 3.5 μm or less. The lower limit of the maximum cross-sectional height (Rt) is not particularly limited, but is usually 0.1 μm or more from the viewpoint of preventing the resin from bleeding and obtaining an insulating layer having a good balance of layer thickness.
The maximum cross-sectional height (Rt) of the carrier film surface can be measured using a non-contact type surface roughness meter. As a specific example of the non-contact type surface roughness meter, “WYKO NT9300” manufactured by Bee Coins Instruments can be cited.

  The carrier film may be peeled off before the step of providing the conductor layer (circuit wiring) on the insulating layer obtained by curing the prepreg, for example, between the step (II) and the step (III) described later. You may peel and may peel after process (III) mentioned later. In a preferred embodiment, the carrier film is peeled after step (III) described below. The carrier film may be peeled off manually or mechanically by an automatic peeling device.

  The lamination process in step (I) can be performed with a commercially available vacuum laminator. Examples of the commercially available vacuum laminator include a vacuum pressure laminator manufactured by Meiki Seisakusho, a vacuum applicator manufactured by Nichigo Morton, and the like.

<Process (II)>
In the step (II), the laminated prepreg with a carrier is smoothed by hot pressing.

  The smoothing process in the step (II) may be performed, for example, by pressing the thermocompression bonding member from the carrier film side. As the thermocompression bonding member, the same member as that described for the step (I) may be used.

  In order to obtain an insulating layer that has excellent surface smoothness and a small thickness difference between the substrate edge and the substrate center and a good balance of the layer thickness, the hot pressing temperature in step (II) should be within a predetermined range. is important. Specifically, when T1 (° C.) is the laminating temperature in step (I) and T2 (° C.) is the hot press temperature in step (II), T2 is set so that T1 and T2 satisfy the relationship of T2 ≦ T1 + 10. It is important to set. From the viewpoint of obtaining an insulating layer that is further excellent in both the surface smoothness and the layer thickness balance, T1 and T2 preferably satisfy the relationship of T2 ≦ T1 + 5, and more preferably satisfy the relationship of T2 ≦ T1. T2 is not particularly limited as long as the relational expression with T1 is satisfied and the melt viscosity of the prepreg at T2 is within the above specific range, but the lower limit is usually 70 ° C. The upper limit is 160 ° C. The hot pressing temperature in step (II) refers to the surface temperature of the thermocompression bonding member. When pressing through an elastic material such as heat-resistant rubber, the temperature of the surface of the elastic material to be joined to the prepreg with a carrier is determined. Say.

  The pressure-bonding pressure and the pressure-bonding time during the smoothing treatment can be the same as the lamination processing conditions in the step (I). In addition, the smoothing treatment is preferably performed under normal pressure (under atmospheric pressure).

  The smoothing treatment in step (II) may be performed once or twice or more. When the smoothing process is performed twice or more, it may be performed twice or more under the same condition, or may be performed twice or more under different conditions. For example, when the smoothing process in step (II) is performed twice, the hot press temperature in the first smoothing process is T2 (° C.), and the hot press temperature in the second smoothing process is T3 (° C.). In this case, T2 and T3 preferably satisfy the relationship of T2-30 ≦ T3 ≦ T2 + 20, and more preferably satisfy the relationship of T2-20 ≦ T3 ≦ T2 + 10.

  The smoothing process of process (II) can be performed with a commercially available laminator. In addition, you may perform process (I) and process (II) continuously using said commercially available vacuum laminator. For example, the step (I) and the step (II) may be continuously performed using a vacuum laminator including a first chamber for laminating processing and a second chamber for smoothing processing. When the smoothing process of step (II) is performed twice or more, the smoothing process may be repeated twice or more in the second chamber, or a further step for performing the second and subsequent smoothing processes. Smoothing treatment may be performed twice or more using a vacuum laminator including chambers (for example, the third chamber and the fourth chamber).

<Step (III)>
In step (III), the prepreg is thermally cured to form an insulating layer.

  The conditions for thermosetting are not particularly limited, and the conditions normally employed when forming the insulating layer of the multilayer printed wiring board may be used.

  For example, the thermosetting conditions of the prepreg differ depending on the composition of the resin composition used for the prepreg, but the curing temperature is in the range of 120 ° C to 240 ° C (preferably in the range of 150 ° C to 210 ° C, more preferably in the range of 170 ° C to 190 ° C.), and the curing time can be in the range of 5 minutes to 90 minutes (preferably 10 minutes to 75 minutes, more preferably 15 minutes to 60 minutes).

  Prior to thermosetting, the prepreg may be preheated at a temperature lower than the curing temperature. For example, prior to thermosetting, the prepreg is kept at a temperature of 50 ° C. or higher and lower than 120 ° C. (preferably 60 ° C. or higher and 110 ° C. or lower, more preferably 70 ° C. or higher and 100 ° C. or lower) for 5 minutes or longer (preferably 5 minutes to 150 ° C. Minutes, more preferably 15 minutes to 120 minutes). When preheating is performed, such preheating is also included in step (III).

  The thermal curing of the prepreg in the step (III) is preferably performed under atmospheric pressure (normal pressure).

  The thermal curing in step (III) may be performed using a heating oven. When heat-curing a prepreg using a heating oven, a large number of the prepregs are placed in the heating oven at a time by placing the prepreg vertically in the heating oven and thermally curing to form an insulating layer. This enables continuous and smooth work from step (II) to step (III) and contributes to productivity improvement. As the heating oven, for example, a clean oven (“Clean Oven DE610” manufactured by Yamato Scientific Co., Ltd.) or the like can be used.

  By the step (III), a laminate including an inner layer circuit board and an insulating layer bonded to the inner layer circuit board is obtained. As described above, when using a prepreg having a high total content of the fiber base material and the inorganic filler, the thermal expansion coefficient of the obtained insulating layer can be kept low, while the surface of the obtained insulating layer is a base layer. It has undulations corresponding to the surface irregularities of a certain inner layer circuit board, and it is difficult to obtain an insulating layer having a smooth surface. If the undulation on the surface of the insulating layer is large, it may become an obstacle when forming a conductor layer with a fine wiring pattern on the surface of the insulating layer. Although the surface smoothness of the insulating layer can be somewhat improved by hot pressing under conditions that increase the fluidity of the resin, such as setting the hot press temperature in the smoothing process high, in such a case The balance of the thickness of the insulating layer is lost due to the seepage of the resin and the like, and there is a tendency that a large difference occurs in the thickness of the obtained insulating layer between the central portion of the substrate and the end portion of the substrate. According to the recent trend of reducing the thickness of the insulating layer as the multilayer printed wiring board becomes thinner, such a poor balance of the layer thickness may result in a decrease in local insulation reliability. On the other hand, according to the method for producing a multilayer printed wiring board of the present invention, even when using a prepreg having a high total content of the fiber base material and the inorganic filler, the surface smoothness is excellent, and the substrate edge An insulating layer having a good balance of the layer thickness with a small difference in thickness between the center portion and the central portion of the substrate can be formed. Therefore, the present invention significantly contributes to both the fine wiring and thinning of the multilayer printed wiring board when manufacturing the multilayer printed wiring board using the prepreg having a high total content of the fiber base material and the inorganic filler. It is.

The maximum cross-sectional height (Rt) on the surface of the insulating layer after step (III) is preferably less than 3 μm from the viewpoint of forming a conductor layer with a fine wiring pattern on the surface of the insulating layer. It is more preferably 8 μm or less, still more preferably 2.6 μm or less, and even more preferably 2.5 μm or less. The lower limit of the maximum cross-sectional height (Rt) is not particularly limited, but is usually 0.1 μm or more.
The maximum cross-sectional height (Rt) of the insulating layer surface can be measured using a non-contact type surface roughness meter for the exposed surface of the insulating layer after the carrier film is peeled off.

After step (III), the difference between the thickness of the insulating layer at the edge of the substrate and the thickness of the insulating layer at the center of the substrate is less than 2.5 μm from the viewpoint of achieving the desired insulation reliability over the entire substrate. Preferably, it is preferably 2.4 μm or less, more preferably 2.2 μm or less, still more preferably 2.0 or less, and 1.8 μm or less or 1.6 μm or less. It is particularly preferred. The lower limit of the difference between the thickness of the insulating layer at the edge of the substrate and the thickness of the insulating layer at the center of the substrate is not particularly limited, and may be 0 μm. In the present invention, since an insulating layer having a small thickness difference can be formed between the substrate end and the substrate central portion in this way, even if the insulating layer is thin, the desired insulation is achieved over the entire substrate. Reliability can be achieved.
The difference between the thickness of the insulating layer at the end of the substrate and the thickness of the insulating layer at the central portion of the substrate is determined by using a microscope for each cross section of the central portion and the end portion of the laminate obtained in step (III). It can be calculated by measuring the thickness of the insulating layer directly above. Specific examples of the microscope include “Microscope VK-8510” manufactured by KEYENCE Corporation.

<Other processes>
The method for producing a multilayer printed wiring board of the present invention comprises: (IV) a step of drilling an insulating layer; (V) a step of roughening the insulating layer; and (VI) a conductor layer by plating on the surface of the roughened insulating layer. The method may further include the step of forming. These steps (IV) to (VI) may be carried out according to various methods known to those skilled in the art used in the production of multilayer printed wiring boards. In addition, when peeling a carrier film after process (III), peeling of this carrier film is implemented between process (III) and process (IV), or between process (IV) and process (V). It's okay.

  Step (IV) is a step of making a hole in the insulating layer, whereby a via hole or the like can be formed in the insulating layer. The via hole is provided for electrical connection between layers, and can be formed by a known method using a drill, laser, plasma, or the like in consideration of the characteristics of the insulating layer. For example, when a carrier film is present, a via hole can be formed in the insulating layer by irradiating the carrier film with laser light.

  Examples of the laser light source include a carbon dioxide laser, a YAG laser, and an excimer laser. Among these, a carbon dioxide laser is preferable from the viewpoint of processing speed and cost.

  Drilling can be carried out using a commercially available laser device. Examples of commercially available carbon dioxide laser devices include LC-2E21B / 1C manufactured by Hitachi Via Mechanics Co., Ltd., ML605GTWII manufactured by Mitsubishi Electric Co., Ltd., and a substrate drilling laser processing machine manufactured by Matsushita Welding Systems Co., Ltd. Can be mentioned.

  Step (V) is a step of roughening the insulating layer. The procedure and conditions for the roughening treatment are not particularly limited, and known procedures and conditions that are usually used when forming the insulating layer of the multilayer printed wiring board can be adopted. For example, the insulating layer can be roughened by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order. Although it does not specifically limit as a swelling liquid, An alkaline solution, surfactant solution, etc. are mentioned, Preferably it is an alkaline solution, As this alkaline solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferable. Examples of commercially available swelling liquids include Swelling Dip Securigans P and Swelling Dip Securigans SBU manufactured by Atotech Japan. Although the swelling process by a swelling liquid is not specifically limited, For example, it can carry out by immersing an insulating layer for 1 minute-20 minutes in 30-90 degreeC swelling liquid. From the viewpoint of suppressing the swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling solution at 40 to 80 ° C. for 5 seconds to 15 minutes. Although it does not specifically limit as an oxidizing agent, For example, the alkaline permanganate solution which melt | dissolved potassium permanganate and sodium permanganate in the aqueous solution of sodium hydroxide is mentioned. The roughening treatment with an oxidizing agent such as an alkaline permanganic acid solution is preferably performed by immersing the insulating layer in an oxidizing agent solution heated to 60 to 80 ° C. for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as Concentrate Compact P and Dosing Solution Securigans P manufactured by Atotech Japan Co., Ltd. As the neutralizing solution, an acidic aqueous solution is preferable, and as a commercially available product, for example, Reduction Solution / Securigant P manufactured by Atotech Japan Co., Ltd. may be mentioned. The treatment with the neutralizing solution can be performed by immersing the treated surface subjected to the roughening treatment with the oxidant solution in the neutralizing solution at 30 to 80 ° C. for 5 to 30 minutes. From the viewpoint of workability and the like, a method of immersing an object subjected to roughening treatment with an oxidant solution in a neutralizing solution at 40 to 70 ° C. for 5 to 20 minutes is preferable.

  Step (VI) is a step of forming a conductor layer by plating on the roughened insulating layer surface.

  The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer is one or more selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium. Contains metal. The conductor layer may be a single metal layer or an alloy layer. As the alloy layer, for example, an alloy of two or more metals selected from the above group (for example, nickel-chromium alloy, copper- A layer formed from a nickel alloy and a copper / titanium alloy). Among them, from the viewpoint of versatility of conductor layer formation, cost, ease of patterning, etc., single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel / chromium alloy, copper / An alloy layer of nickel alloy or copper / titanium alloy is preferable, and a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or an alloy layer of nickel / chromium alloy is more preferable, and a single layer of copper is preferable. A metal layer is more preferred.

  The conductor layer may have a single layer structure or a multilayer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multilayer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc or titanium, or an alloy layer of nickel / chromium alloy.

  The thickness of the conductor layer depends on the design of the desired multilayer printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

  The conductor layer can be formed by plating. For example, the surface of the insulating layer can be plated by a conventionally known technique such as a semi-additive method or a full additive method to form a conductor layer having a desired wiring pattern. Hereinafter, an example in which the conductor layer is formed by a semi-additive method will be described.

  First, a plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern that exposes a part of the plating seed layer corresponding to a desired wiring pattern is formed on the formed plating seed layer. A metal layer is formed by electrolytic plating on the exposed plating seed layer, and then the mask pattern is removed. Thereafter, an unnecessary plating seed layer can be removed by etching or the like to form a conductor layer having a desired wiring pattern. In the manufacturing method of the multilayer printed wiring board of this invention, since the insulating layer excellent in surface smoothness can be formed, a conductor layer can be formed with a fine wiring pattern on this insulating layer.

  A semiconductor device can be manufactured by using the multilayer printed wiring board manufactured by the method of the present invention. A semiconductor device can be manufactured by mounting a semiconductor chip in a conductive portion of the multilayer printed wiring board of the present invention. The “conduction location” is a “location where an electrical signal is transmitted in a multilayer printed wiring board”, and the location may be a surface or an embedded location. The semiconductor chip is not particularly limited as long as it is an electric circuit element made of a semiconductor.

  The semiconductor chip mounting method for manufacturing the semiconductor device of the present invention is not particularly limited as long as the semiconductor chip functions effectively, but specifically, a wire bonding mounting method, a flip chip mounting method, and no bumps. Examples include a mounting method using a build-up layer (BBUL), a mounting method using an anisotropic conductive film (ACF), and a mounting method using a non-conductive film (NCF).

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In the following description, “part” means “part by mass”.

  First, measurement methods and evaluation methods in the physical property evaluation in this specification will be described.

[Preparation of measurement and evaluation substrate]
(1) Production of inner layer circuit board IPC MULTI- on glass cloth base epoxy resin double-sided copper-clad laminate (copper foil thickness 35 μm, board thickness 0.8 mm, Matsushita Electric Works “R5715ES”) PURPOSE TEST BOARD NO. An IPC C-25 pattern (line / space ratio = 600/660 μm comb tooth pattern (residual copper ratio 48%)) was formed. Subsequently, the both surfaces of the substrate were roughened with a microetching agent (“CZ8100” manufactured by MEC Co., Ltd.) to produce an inner layer circuit board.
In addition, regarding Example 4, the glass cloth base-material epoxy resin double-sided copper clad laminated board which changed the thickness of copper foil to 7 micrometers was used.

(2) Lamination of prepreg with carrier The prepreg with carrier produced in the following production example was bonded to the inner circuit board using a laminator with two-chamber press ("MVLP500 / 600-IIB" manufactured by Meiki Co., Ltd.). In this way, lamination was performed on both sides of the inner circuit board. The laminating process was performed by reducing the pressure for 30 seconds to a pressure of 13 hPa or less, and then pressing the laminate for 30 seconds at a lamination temperature T1 (° C.) and a pressure of 0.74 MPa shown in Table 2. Lamination was performed in the first chamber of a laminator with a two-chamber press.

(3) Smoothing of prepreg with carrier The laminated prepreg with carrier was smoothed by hot pressing in the second chamber of the laminator with two-chamber press. The smoothing treatment was performed by pressure bonding for 90 seconds at a hot press temperature T2 (° C.) and a pressure of 0.55 MPa shown in Table 2 under atmospheric pressure (normal pressure).
In addition, regarding Example 7, the smoothing process was implemented twice in the 2nd chamber of the laminator with the said 2 chamber press. The first smoothing treatment was performed by pressure bonding at a hot press temperature T2 (° C.) and a pressure of 0.55 MPa shown in Table 2 for 90 seconds under atmospheric pressure (normal pressure). The second smoothing treatment was performed by pressure bonding at a hot press temperature T3 (° C.) and a pressure of 0.55 MPa shown in Table 2 for 90 seconds under atmospheric pressure (normal pressure).

(4) Thermosetting of prepreg After smoothing, the substrate was heated at 180 ° C. for 30 minutes, and the prepreg was thermoset to form an insulating layer.

<Measurement of melt viscosity of prepreg>
A measurement sample was prepared by punching out 20 prepregs having a thickness of 1 mm by overlapping 20 sheets. About the prepared measurement sample, melt viscosity was measured using the dynamic viscoelasticity measuring apparatus ("Rheogel-G3000" by UBM Co., Ltd.). The dynamic viscoelasticity is measured under the measurement conditions of a temperature increase rate of 5 ° C./min, a measurement temperature interval of 2.5 ° C., and a vibration frequency of 1 Hz, and the melt viscosity (poise) at temperature T2 (° C.) shown in Table 2 is obtained. It was. A cone plate was used as a measurement jig.

<Measurement of maximum cross-sectional height (Rt) of carrier film surface after laminating process>
After laminating the prepreg with a carrier on the inner circuit board, a 200 mm × 200 mm evaluation board was cut out, and the maximum cross-sectional height (Rt) of the carrier film surface of the prepreg with a carrier was measured. The maximum cross-sectional height (Rt) of the surface of the carrier film is 0.82 mm × 1.1 mm using a non-contact type surface roughness meter (“WYKO NT9300” manufactured by Beeco Instruments) with a VSI contact mode and a 10 × lens. It calculated | required by the numerical value obtained as. The measurement was performed on the exposed surface of the carrier film with the carrier film attached to the prepreg.

<Measurement of maximum cross-sectional height (Rt) of insulating layer surface>
After thermosetting the prepreg, the release PET film as the carrier film was peeled off, and the maximum cross-sectional height (Rt) was measured for the exposed surface of the insulating layer. The maximum cross-sectional height (Rt) of the surface of the insulating layer can be measured using a non-contact type surface roughness meter (“WYKO NT9300” manufactured by Beeco Instruments Co., Ltd.) with a measurement range of 0.82 mm × 1.1 mm using a VSI contact mode and a 10 × lens. Was obtained from the numerical value obtained as follows. In the measurement, the region where the circuit wiring of the comb-tooth pattern (remaining copper ratio 48%) with the line / space ratio = 600/660 μm is provided so as to straddle the portion with the circuit wiring and the portion without the circuit wiring. It carried out by calculating | requiring the average value of three places.
In Table 2, the case where Rt is less than 2.5 μm is “◯”, the case where it is 2.5 μm or more and less than 3 μm is “Δ”, and the case where it is 3 μm or more is “x”. In Comparative Examples 1, 3, and 5, since wrinkles were generated due to the occurrence of undulations based on the surface irregularities of the inner circuit board, measurement of the maximum cross-sectional height (Rt) was omitted. In Comparative Example 6, since a void was generated, measurement of the maximum cross-sectional height (Rt) was omitted.

<Evaluation of the appearance of the insulating layer surface>
After thermosetting the prepreg, the release PET film as the carrier film was peeled off, and the appearance of the exposed surface of the insulating layer was observed. The appearance of the surface of the insulating layer was observed using a microscope (“Microscope VK-8510” manufactured by KEYENCE Corp.) with a surface of 3 cm ² on the surface of the insulating layer.
In Table 2, the case where there was no wrinkle or void was indicated as “◯”, and the case where there was a wrinkle or void was indicated as “x”.

<Measurement of difference in thickness of insulating layer between substrate edge and substrate center>
After thermosetting the prepreg, the release PET film, which is a carrier film, was peeled off, and the difference in thickness of the insulating layer between the substrate edge and the substrate center was measured. Specifically, for each region (1 cm ² ) of the substrate end and the substrate central portion, the cross section is smoothed by polishing, and then a circuit is used using a microscope (“Microscope VK-8510” manufactured by KEYENCE Corporation). The thickness of the insulating layer immediately above the conductor was measured.
In Table 2, the case where the difference in the thickness of the insulating layer between the substrate end and the center of the substrate is less than 2.5 μm is “◯”, and the case where the difference is 2.5 μm or more is “x”.

[Production Example 1]
(1) Preparation of resin varnish 15 parts of liquid bisphenol A type epoxy resin (epoxy equivalent 180, “jER828EL” manufactured by Mitsubishi Chemical Corporation), naphthalene type tetrafunctional epoxy resin (epoxy equivalent 163, “HP4710” manufactured by DIC Corporation) ) 25 parts, 45 parts of naphthylene ether type epoxy resin (epoxy equivalent 213, “EXA-7311G4” manufactured by DIC Corporation), and 8 parts of phenoxy resin (“YL7553BH30” manufactured by Japan Epoxy Resin Corporation), 30 parts of MEK And dissolved in 30 parts of cyclohexanone by heating with stirring. Thereto, 10 parts of a MEK solution having a solid content of 60% by mass of a triazine skeleton-containing phenolic curing agent (hydroxyl equivalent: 125, “LA7054” manufactured by DIC Corporation, nitrogen content: about 12% by mass), naphthalene type curing agent (functional 40 parts by weight of MEK solution with a solid content of 60 wt% in a base equivalent of 153, “HPC9500” manufactured by DIC Corporation, flame retardant (hydroxyl equivalent of 162, “HCA-HQ” manufactured by Sanko Co., Ltd.), phosphorus content of 9.5% ) 8 parts, 250 parts of spherical silica (average particle size 1.0 μm, manufactured by Admatechs Co., Ltd. “SOC4”) surface-treated with an aminosilane coupling agent (“KBM-573” manufactured by Shin-Etsu Chemical Co., Ltd.) The mixture was mixed and uniformly dispersed with a high-speed rotary mixer to prepare a resin varnish.

(2) Preparation of prepreg 1 with carrier The resin varnish obtained in (1) above was impregnated into a fiber base material (1027 glass cloth, thickness 19 μm, manufactured by Arisawa Manufacturing Co., Ltd.), and 110 in a vertical drying furnace. A prepreg was prepared by drying at 5 ° C. for 5 minutes. The resin composition content in the prepreg was 81% by mass, and the thickness of the prepreg was 50 μm. Then, using a batch-type vacuum pressurization laminator (“MVLP-500” manufactured by Meiki Seisakusho Co., Ltd.), a PET film with a release layer (“PET501010” manufactured by Lintec Corporation, thickness 38 μm) is released. The prepreg 1 with a carrier was formed by laminating on both sides of the prepreg so that the layer was in contact with the prepreg. In the prepreg 1 with the carrier, the total content of the fiber base material and the inorganic filler in the prepreg was 72% by mass. When producing an evaluation board | substrate, it peeled and used one PET film (protective film) with a release layer.

[Production Example 2]
(1) Preparation of resin varnish A resin varnish was prepared in the same manner as in Preparation Example 1.

(2) Preparation of prepreg 2 with a carrier A fiber substrate (1000 glass cloth, thickness 14 μm manufactured by Arisawa Manufacturing Co., Ltd.) was used instead of the fiber substrate (1027 glass cloth, thickness 19 μm manufactured by Arisawa Manufacturing Co., Ltd.) A prepreg 2 with a carrier was prepared in the same procedure as in Production Example 1 except that. The resin composition content in the prepreg was 80% by mass, and the thickness of the prepreg was 33 μm. Moreover, in the prepreg 2 with a carrier, the total content of the fiber base material and the inorganic filler in the prepreg was 72% by mass.

[Production Example 3]
(1) Preparation of resin varnish 15 parts of liquid bisphenol A type epoxy resin (epoxy equivalent 180, “jER828EL” manufactured by Mitsubishi Chemical Corporation), naphthylene ether type epoxy resin (epoxy equivalent 213, manufactured by DIC Corporation “EXA-” 7311G4 ") and 8 parts of phenoxy resin (" YL7553BH30 "manufactured by Japan Epoxy Resin Co., Ltd.) were dissolved in a mixed solvent of 20 parts of MEK and 20 parts of cyclohexanone with stirring. Thereto, 10 parts of a MEK solution having a solid content of 60% by weight of a triazine skeleton-containing phenolic resin (hydroxyl equivalent: 125, “LA7054” manufactured by DIC Corporation, nitrogen content: about 12% by weight), naphthalene type curing agent (functional group) Equivalent 215, 40 parts by weight of MEK solution 60% solids by Nippon Steel Co., Ltd. “SN485”, flame retardant (hydroxyl equivalent 162, “HCA-HQ” manufactured by Sanko Co., Ltd., phosphorus content 9.5 %) 8 parts, spherical silica surface treated with an aminosilane coupling agent (“KBM-573” manufactured by Shin-Etsu Chemical Co., Ltd.) (average particle size 1.0 μm, “SOC4” manufactured by Admatechs Co., Ltd.) 240 parts And uniformly dispersed with a high-speed rotary mixer to prepare a resin varnish.
(2) Preparation of prepreg 3 with carrier Using the resin varnish obtained in (1) above, prepreg 3 with carrier was prepared in the same procedure as in Production Example 1. The resin composition content in the prepreg was 81% by mass, and the thickness of the prepreg was 50 μm. Moreover, in the prepreg 3 with a carrier, the total content of the fiber base material and the inorganic filler in the prepreg was 71% by mass.

<Example 1>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 140 ° C. Each evaluation result is shown in Table 2.

<Example 2>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 120 ° C. Each evaluation result is shown in Table 2.

<Example 3>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 120 ° C., and the hot press temperature T2 was 120 ° C. Each evaluation result is shown in Table 2.

<Example 4>
Using the prepreg 2 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 120 ° C. Each evaluation result is shown in Table 2.

<Example 5>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 130 ° C., and the hot press temperature T2 was 110 ° C. Each evaluation result is shown in Table 2.

<Example 6>
Using the prepreg 3 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 130 ° C., and the hot press temperature T2 was 110 ° C. Each evaluation result is shown in Table 2.

<Example 7>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., the hot press temperature T2 was 140 ° C., and the hot press temperature T3 was 120 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 1>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 160 ° C. Each evaluation result is shown in Table 2.

<Comparative example 2>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 100 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 3>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 120 ° C., and the hot press temperature T2 was 140 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 4>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 120 ° C., and the hot press temperature T2 was 100 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 5>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 100 ° C., and the hot press temperature T2 was 140 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 6>
Using the prepreg 1 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 100 ° C., and the hot press temperature T2 was 100 ° C. Each evaluation result is shown in Table 2.

<Comparative Example 7>
Using the prepreg 3 with a carrier, an evaluation substrate was prepared according to the procedure of [Preparation of measurement / evaluation substrate]. As shown in Table 2, the lamination temperature T1 was 140 ° C., and the hot press temperature T2 was 140 ° C. Each evaluation result is shown in Table 2.

Claims (9)

A prepreg with a carrier prepreg is formed on (I) a carrier film, as Prin prepreg is bonded to the inner layer circuit board, a step of laminating the inner layer circuit board,
(II) A method for producing a multilayer printed wiring board comprising a step of smoothing a laminated prepreg with a carrier by hot pressing, and (III) a step of thermally curing the prepreg to form an insulating layer,
When the total mass of the prepreg is 100% by mass, the total mass of the fiber base material and the inorganic filler in the prepreg is 70% by mass or more,
The melt viscosity of the prepreg at the hot press temperature in step (II) is 300 to 10,000 poise,
The maximum cross-sectional height (Rt) of the carrier film surface of the prepreg with a carrier after step (I) is less than 5 μm, and the laminating temperature in step (I) is T1 (° C.), and the hot press temperature in step (II) And T2 (° C.), T1 and T2 satisfy the relationship of T2 ≦ T1 + 10. A method for producing a multilayer printed wiring board,   The method according to claim 1, wherein T1 and T2 satisfy a relationship of T2 ≦ T1 + 5.   The method according to claim 1 or 2, wherein step (II) is carried out twice or more.   The method as described in any one of Claims 1-3 whose maximum cross-sectional height (Rt) of the surface of an insulating layer after process (III) is less than 3 micrometers.   The method according to claim 1, wherein the prepreg further contains an epoxy resin and a curing agent.   The method according to any one of claims 1 to 5, wherein the prepreg is formed by impregnating a fiber base material with a resin composition containing an epoxy resin, a curing agent and an inorganic filler. The content ratio (mass ratio of fiber base material / inorganic filler) of the fiber base material and the inorganic filler in the prepreg is 0.2 to 2.5, according to any one of claims 1 to 6. Method. The method according to any one of claims 1 to 7 , wherein the carrier film is peeled off after the step (III). The method according to any one of claims 1 to 8 , wherein in step (III), the prepreg is placed in a vertical state in a heating oven and thermally cured to form an insulating layer.