JP5728998B2 - Insulating resin material for wiring board, multilayer wiring board, and method for manufacturing multilayer wiring board - Google Patents

Description

  The present invention is a build-up multilayer wiring board that exhibits high adhesion to electroless plating even on a smooth resin surface, has a low coefficient of thermal expansion, excellent workability and heat resistance, and can form fine circuits. The present invention relates to an insulating resin material for wiring boards that can provide a highly reliable multilayer wiring board, a multilayer wiring board, and a method for manufacturing the multilayer wiring board.

  In order to manufacture a multilayer wiring board, a material called a prepreg, which is impregnated with epoxy resin in a semi-cured state, is laminated with a copper foil on an insulating substrate having an inner layer circuit formed on one or both sides by hot pressing. After stacking and integrating, drill holes called through holes for interlayer connection are drilled, and electroless plating is performed on the inner wall of the through hole and the copper foil surface. After making the thickness, it is common to produce a multilayer wiring board by removing unnecessary copper.

However, in recent years, electronic devices have been further reduced in size, weight, and functionality, and along with this, LSIs and chip components have been highly integrated, and their forms have rapidly changed to multiple pins and downsizing. ing. For this reason, in order to improve the mounting density of electronic components, multilayer wiring boards are being developed for fine wiring. Further, it is required to have a low linear thermal expansion coefficient.
As a manufacturing method of multilayer wiring boards that meet these requirements, a build-up multilayer that uses insulating resin that does not contain glass cloth as an insulating layer instead of prepreg, and forms wiring layers while connecting only necessary parts with via holes. There is a wiring board, and it is becoming mainstream as a technique suitable for weight reduction, miniaturization, and miniaturization.

In such a build-up type multilayer wiring board, an insulating resin film is laminated on an inner circuit board, cured by heating, then a via hole is formed by laser processing, and roughening treatment and smear treatment are performed by alkali permanganate treatment or the like. And performing electroless copper plating to form via holes that allow interlayer connection with the second circuit (see, for example, Patent Documents 1 to 3).
In this build-up method, the adhesive force between the resin and the electroless copper plating is ensured by the roughness of the resin surface (anchor effect), the surface roughness (Ra) is 0.5 μm or more, and the surface roughness is large.

In this build-up type multilayer wiring board, further miniaturization of the circuit is required with the recent miniaturization and higher density of the semiconductor package.
In such a situation, a fine circuit having a size of 10 μm or less is obtained by a method of securing an adhesive force with electroless copper plating using a large roughened shape (anchor effect) obtained by roughening the surface as in the prior art. Short circuit defects and open defects occur, making it impossible to manufacture with good yield. On the other hand, if the roughened shape is reduced, the adhesive strength with the electroless copper plating decreases, and defects such as peeling of the line occur. Therefore, the insulating resin exhibits electroless copper plating and high adhesive strength on a smooth surface. A film is required.

  Also, an insulating film having a two-layer structure of an adhesive layer containing an electroless copper plating catalyst and an insulating resin layer is disclosed for the purpose of ensuring adhesion between the electroless copper plating and the resin. However, in this insulating film having a two-layer structure, the roughened shape of the surface is not smoothed, which is insufficient as a recent miniaturized semiconductor package substrate (see, for example, Patent Document 4). .

Furthermore, there is an active movement to regulate electronic materials and other materials that may generate harmful substances during combustion due to increased environmental awareness. In conventional multilayer wiring boards, bromine compounds that may generate harmful substances during combustion have been used for flame resistance, but such bromine compounds are expected to be unusable in the near future. Is done.
Also, lead-free solder that does not contain lead is also being put into practical use as a solder generally used for connecting electronic components to a multilayer wiring board. This lead-free solder has a use temperature higher than that of a conventional eutectic solder by about 20 to 30 ° C. Therefore, the material is required to have higher solder heat resistance than ever before.

Japanese Patent Laid-Open No. 7-304931 Japanese Patent Laid-Open No. 2002-3705 JP-A-11-1547 JP-A-1-99288

  In view of the current situation, the object of the present invention is a build-up type multilayer wiring board, which exhibits high adhesive strength with electroless plating even on a smooth resin surface, has a low thermal expansion coefficient, excellent workability and heat resistance, and is fine. It is to provide an insulating resin material for a wiring board, a multilayer wiring board, and a method for manufacturing the multilayer wiring board, which can form a reliable circuit and can provide a highly reliable multilayer wiring board.

As a result of intensive research to achieve the above object, the present inventors have made an insulating resin layer an epoxy resin containing a bismaleimide compound, and a pre-reaction of a polyfunctional epoxy resin and an epoxy resin curing agent in an adhesion auxiliary layer. In addition, by providing an adhesion auxiliary layer having a thickness of 1 to 10 μm made of a resin composition containing a crosslinked organic filler having an average primary particle size of 1 μm or less, good adhesion can be achieved even on a smooth resin surface with Ra of 0.3 μm or less. Insulating resin materials for wiring boards that can secure high reliability and high reliability have been found.
By using a resin composition containing 20% by mass or more of a crosslinked organic filler having an average primary particle size of 1 μm or less, heat resistance is improved as compared with the case of using a crosslinked organic filler having an average primary particle size of greater than 1 μm. It is possible to toughen the resin and increase the elongation without lowering, and furthermore, a very fine and dense rough shape with Ra of 0.3 μm or less is obtained, and the adhesiveness with the plated copper is remarkably improved. To do.
Furthermore, by pre-reacting the polyfunctional epoxy resin and the epoxy resin curing agent and adjusting the molecular weight and melt viscosity of the resin, in the insulating film having a two-layer structure of the adhesion auxiliary layer and the insulating resin layer, the resin components are mutually bonded. Transition to each layer can be suppressed, and stable adhesive strength is expressed. In addition, when using a crystalline curing agent such as dicyandiamide, it may remain alone in the resin composition, and there is concern about a decrease in resistance to electric corrosion, but by reacting with an epoxy resin by a preliminary reaction, It will not crystallize and remain alone.

That is, the present invention provides the following insulating resin material for wiring boards, multilayer wiring boards, and methods for producing multilayer wiring boards.
1. It has an insulating resin layer (A) and an adhesion auxiliary layer (B). The insulating resin layer (A) is composed of a polyfunctional epoxy resin (a-1), a bismaleimide compound (a-2), an epoxy resin curing agent ( a-3) and an inorganic filler (a-4) containing layer, the adhesion auxiliary layer (B) is a pre-reaction of the polyfunctional epoxy resin (b-1) and the epoxy resin curing agent (b-2) An insulating resin material for a wiring board comprising a product and a crosslinked organic filler (b-3) having an average primary particle size of 1 μm or less and a thickness of 1 to 10 μm.
2. The insulating resin material for a wiring board according to 1 above, wherein the insulating resin layer (A) further contains a phosphorus-based flame retardant (a-5).
3. 3. The insulating resin material for a wiring board according to 1 or 2 above, wherein the adhesion auxiliary layer (B) further contains fumed silica (b-4).
4). The insulating resin material for a wiring board according to any one of 1 to 3, wherein the crosslinked organic filler (b-3) contained in the adhesion auxiliary layer (B) is a core-shell structured crosslinked rubber particle.
5. The insulating resin material for a wiring board according to any one of 1 to 4, wherein the content of the crosslinked organic filler (b-3) based on solid content in the adhesion auxiliary layer (B) is 20 to 40% by mass.
6). The multifunctional epoxy resin (b-1) in the adhesion auxiliary layer (B) is an aralkyl epoxy resin having a biphenyl structure, and the epoxy resin curing agent (b-2) is a triazine ring-containing novolac phenol resin and / or dicyandiamide The insulating resin material for a wiring board according to any one of 1 to 5 above.
7). The insulating resin material for wiring boards according to any one of 1 to 6 above, wherein the surface roughness (Ra) of the adhesion auxiliary layer (B) after curing and roughening the insulating resin material for wiring boards is 0.3 μm or less.
8). A multilayer wiring board in which an insulating layer and an outer layer circuit layer are sequentially laminated on one or both sides of a substrate having an inner layer circuit, wherein the insulating layer is a cured product of the insulating resin material for a wiring board according to any one of 1 to 7 above. A multilayer wiring board characterized by being.
9. A step (a) of laminating the insulating resin material for a wiring board according to any one of 1 to 7 above on a substrate having an inner layer circuit, a step (b) of obtaining the insulating layer by curing the insulating resin material for a wiring board, and the insulating layer A method for producing a multilayer wiring board, comprising a step (c) of forming an outer circuit layer on a surface.

According to the present invention, in a multilayer wiring board of a build-up system, even a smooth resin surface exhibits high adhesion with electroless plating, has a low thermal expansion coefficient, excellent workability and heat resistance, and can form fine circuits. An insulating resin material for a wiring board that is possible and highly reliable is provided.
In addition, according to the present invention, the insulating resin material for wiring boards has high flame resistance without using any bromine compound that may adversely affect the environment, and has high solder heat resistance that can be made lead-free. I will provide a.
In addition, according to the method for manufacturing a multilayer wiring board in the present invention, when the interlayer connection via is formed by the laser, a defect in which only the adhesion auxiliary layer remains does not occur.

It is sectional drawing explaining an example of the process of manufacturing the multilayer wiring board of this invention.

Hereinafter, the present invention will be described in detail.
The insulating resin material for a wiring board of the present invention has an insulating resin layer (A) and an adhesion auxiliary layer (B), and the insulating resin layer (A) is a polyfunctional epoxy resin (a-1), a bismaleimide compound. (A-2) is a layer containing an epoxy resin curing agent (a-3) and an inorganic filler (a-4). The adhesion auxiliary layer (B) is a polyfunctional epoxy resin (b-1), epoxy It contains a preliminary reaction product of a resin curing agent (b-2) and a crosslinked organic filler (b-3) having an average primary particle size of 1 μm or less, and is a layer having a thickness of 1 to 10 μm. is there.

  First, the insulating resin layer (A) of the insulating resin material for wiring boards of the present invention comprises a polyfunctional epoxy resin (a-1), a bismaleimide compound (a-2), an epoxy resin curing agent (a-3) and It is a layer containing an inorganic filler (a-4), and preferably further contains a phosphorus-based flame retardant (a-5).

The polyfunctional epoxy resin (a-1) is an epoxy resin having two or more epoxy groups in the molecule, and examples thereof include a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, and an aralkyl type epoxy resin.
It is preferable that the compounding quantity of the polyfunctional epoxy resin (a-1) in an insulating resin layer (A) is 20-50 mass% in the total solid of the composition for insulating resin layers except a solvent. When the blending amount of the component (a-1) is 20% by mass or more, the solder heat resistance is improved, and when it is 50% by mass or less, the adhesive strength with the circuit conductor does not decrease. Further, when a liquid epoxy resin is used in combination as the polyfunctional epoxy resin, the fluidity of the resin is improved, so that it is preferably used.

Any bismaleimide compound (a-2) can be used as long as it is soluble in a solvent. As the bismaleimide compound, for example, BMI-2300 and BMI-4000 manufactured by Daiwa Kasei can be used, and a modified bismaleimide compound obtained by heating aminophenols and diamines in a solvent and Michael addition can also be used. . In particular, a modified bismaleimide compound obtained by Michael addition of aminophenols has a phenolic hydroxyl group capable of reacting with an epoxy resin, so that it can be compatible with the epoxy resin and can be preferably used. The modified bismaleimide resin obtained by Michael addition preferably has an amino group in an amount of 0.1 to 0.5 equivalents relative to the maleimide group. When the amount is 0.1 equivalent or more, compatibility with the epoxy resin is obtained, and when the amount is 0.5 equivalent or less, the heat resistance does not decrease.
As for the compounding quantity of a bismaleimide compound (a-2), 100-900 mass parts is preferable with respect to 100 mass parts of epoxy resins. A low coefficient of thermal expansion can be obtained by setting the blending amount of the bismaleimide compound to 100 parts by mass or more, and the reaction does not decrease by setting it to 900 parts by mass or less, and the reaction is completed at a curing temperature of about 200 ° C. be able to.

As the epoxy resin curing agent (a-3), various phenol resins, acid anhydrides, amines, hydragits and the like can be used. Examples of phenolic resins include novolak-type phenolic resins and resol-type phenolic resins, examples of acid anhydrides include phthalic anhydride, benzophenonetetracarboxylic dianhydride, and methyl hymic acid, and examples of amines include dicyandiamide and diaminodiphenylmethane. , Guanylurea and the like. In order to improve reliability, a novolac type phenol resin is preferable.
It is preferable that the usage-amount of an epoxy resin hardening | curing agent (a-3) is 0.5-1.5 equivalent with respect to an epoxy group. Adhesion with the outer layer copper is improved by setting the epoxy resin curing agent to 0.5 equivalent or more with respect to the epoxy group, and the glass transition temperature (Tg) and insulating properties are reduced by setting the epoxy resin curing agent to 1.5 equivalent or less. There is nothing.

In addition to the epoxy resin curing agent (a-3), a reaction accelerator can be used in the insulating resin layer (A) as necessary. As the reaction accelerator, various imidazoles and BF ₃ amine complexes which are latent thermosetting agents can be used. From the viewpoint of storage stability of the insulating resin layer composition, handling property of the B-stage (semi-cured) insulating resin layer composition and solder heat resistance, 2-phenylimidazole and 2-ethyl- 4-methylimidazole is preferably used.
As for the compounding quantity of an epoxy resin hardening | curing agent (a-3), 0.2-1.0 mass part is preferable with respect to 100 mass parts of epoxy resins. When the content is 0.2 parts by mass or more, solder heat resistance is obtained. When the content is 1.0 parts by mass or less, the storage stability of the composition for insulating resin layers and the B-stage composition for insulating resin layers are obtained. The handleability of the is not reduced.

As the inorganic filler (a-4), for example, those selected from silica, fused silica, talc, alumina, aluminum hydroxide, barium sulfate, calcium hydroxide, aerosil, and calcium carbonate can be used. You may mix and use. From the viewpoint of flame retardancy and low thermal expansion, it is preferable to use aluminum hydroxide and silica alone or in combination.
It is preferable that the compounding quantity of an inorganic filler (a-4) shall be 10-50 mass% in solid content of the whole composition for insulating resin layers except a solvent. More preferably, it is 30 to 40% by mass. When it is 10% by mass or more, low thermal expansion is obtained, and when it is 50% by mass or less, laser workability is not lowered.

The phosphorus-based flame retardant (a-5) optionally blended preferably has reactivity with an epoxy resin in view of insulation reliability and heat resistance. For example, HCA-HQ (trade name) manufactured by Sanko Co., Ltd. And XZ92741 (trade name) manufactured by Dow Chemical Co., Ltd. can be used.
It is difficult for the content of the phosphorus-based flame retardant (a-5) to be in the range of 0.7 to 3% by mass in the solid content of the composition for an insulating resin layer excluding the inorganic filler. It is preferable in order to develop flammability. When the phosphorus content is 0.7% by mass or more, flame retardancy is exhibited, and when the phosphorus content is 3% by mass or less, the solder heat resistance is not lowered.

  For the insulating resin layer (A), in addition to the above (a-1) to (a-5), a thixotropic agent, a surfactant, a coupling agent and the like used in a normal insulating resin layer composition These various additives can be appropriately blended. After sufficiently stirring these, the resin composition for the insulating resin layer (A) can be obtained by standing until the bubbles disappear.

It is preferable from the viewpoint of workability that the composition for the insulating resin layer (A) is mixed in a solvent and diluted or dispersed to form a varnish. As this solvent, methyl ethyl ketone, xylene, toluene, acetone, ethylene glycol monoethyl ether, cyclohexanone, ethyl ethoxypropionate, N, N-dimethylformamide, N, N-dimethylacetamide and the like can be used. These solvents may be used alone or in a mixed system. The ratio of the solvent to the composition for the resin layer (A) may be a ratio that can generally be used as a varnish, and the use amount thereof is adjusted according to the equipment for forming the coating film of the composition for the insulating resin layer (A). To do.
When the composition for insulating resin layer (A) is applied to a carrier film or copper foil with a comma coater, the use of a solvent is used so that the solid content of the resin layer composition excluding the solvent is 30 to 60% by mass in the varnish. It is preferred to adjust the amount.
The thickness of the insulating resin layer (A) in the insulating resin material for wiring boards of the present invention is preferably 10 to 100 μm, and more preferably 15 to 60 μm.

The multifunctional epoxy resin (b-1) in the adhesion auxiliary layer (B) is an epoxy resin having two or more epoxy groups in the molecule, such as a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, or an aralkyl type. An epoxy resin etc. are mentioned.
In particular, the polyfunctional epoxy resin (b-1) in the adhesion auxiliary layer (B) desirably contains an aralkyl novolac epoxy resin or an aralkyl novolac epoxy resin. The aralkyl novolac type epoxy resin is preferably an aralkyl novolak type epoxy resin having a biphenyl structure.
The novolak type epoxy resin having a biphenyl structure is an aralkyl novolak type epoxy resin containing an aromatic ring of a biphenyl derivative in the molecule, and examples thereof include an epoxy resin represented by the following general formula (1). . These may be used alone or in combination of two or more.

（式中、ｐは１〜５の数を示す。）

(In formula, p shows the number of 1-5.)

As a commercial item of the epoxy resin represented by the above general formula (1), NC-3000 (epoxy resin of the general formula (1) having p of 1.7) manufactured by Nippon Kayaku Co., Ltd., NC-3000-H (Epoxy resin of general formula (1) where p is 2.8).
The blending amount of the polyfunctional epoxy resin (b-1) in the adhesion auxiliary layer (B) is preferably 20 to 50% by mass in the total solid content excluding the solvent. When the polyfunctional epoxy resin (b-1) is 20% by mass or more, the solder heat resistance is improved, and when it is 50% by mass or less, the adhesive strength with the circuit conductor is improved.

Examples of the epoxy resin curing agent (b-2) in the adhesion auxiliary layer (B) include various phenol resins, acid anhydrides, amines, hydrazines, and the like. Examples of phenolic resins include novolak-type phenolic resin and resol-type phenolic resin. Examples of acid anhydrides include phthalic anhydride, benzophenonetetracarboxylic dianhydride, methylhymic acid, and the like. Examples of amines include dicyandiamide and diaminodiphenylmethane. , Guanylurea and the like.
The epoxy resin curing agent (b-2) is preferably a novolak type phenol resin in order to improve reliability, and if it is a triazine ring-containing novolac type phenol resin or dicyandiamide, the metal foil peel strength and chemical roughening are preferred. Since the peel strength of the electroless plating after the formation is improved, it is more preferably used.

The above-mentioned triazine ring-containing novolak type phenol resin indicates a novolak type phenol resin containing a triazine ring in the main chain of the novolak type phenol resin, and may be a cresol novolak type phenol resin containing a triazine ring. The nitrogen content is preferably 10 to 25% by mass, more preferably 12 to 19% by mass in the triazine ring-containing novolac type phenol resin. When the nitrogen content in the molecule is within this range, the dielectric loss does not become too large, and when the stress relaxation layer is used as a varnish, the solubility in the solvent is appropriate, and the residual amount of undissolved material can be suppressed. . As the triazine ring-containing novolac type phenol resin, one having a number average molecular weight of 500 to 600 can be used. These may be used alone or in combination of two or more.

The triazine ring-containing novolac-type phenol resin can be obtained by reacting phenol, aldehyde, and a triazine ring-containing compound under conditions of pH 5-9. When cresol is used instead of phenol, a triazine ring-containing cresol novolac type phenol resin is obtained. Any of o-, m-, and p-cresol can be used as the cresol, and melamine, guanamine and derivatives thereof, cyanuric acid and derivatives thereof can be used as the triazine ring-containing compound.
As a commercial item of a triazine ring-containing novolac type phenol resin, Dainippon Ink & Chemicals, Inc., a triazine ring-containing cresol novolac type phenol resin phenolite EXB-9829 (nitrogen content 18% by mass) can be mentioned.

  The epoxy resin curing agent (b-2) in the adhesion auxiliary layer (B) is preferably 0.5 to 1.5 equivalents relative to the epoxy group. When the epoxy resin curing agent is 0.5 equivalent or more with respect to the epoxy group, the adhesiveness with the outer layer copper is improved, and when it is 1.5 equivalent or less, the glass transition temperature (Tg) and the insulation are lowered. There is nothing.

In the present invention, a preliminary reaction product of a polyfunctional epoxy resin (b-1) and an epoxy resin curing agent (b-2) is used in the adhesion auxiliary layer (B).
The preliminary reaction between the polyfunctional epoxy resin (b-1) and the epoxy resin curing agent (b-2) is to adjust the molecular weight and melt viscosity of the resin so that the insulating resin layer (A) and the adhesion auxiliary layer (B) In the film having the two-layer structure, it is necessary to suppress the migration of the resin components to each other and to develop stable adhesive strength. In addition, when a crystalline curing agent such as dicyandiamide is used, it may remain alone in the auxiliary adhesion layer (B), and there is a concern about a decrease in electric corrosion resistance. By reacting the curing agent, it does not crystallize and remain alone.
In the preliminary reaction, a solvent that dissolves the polyfunctional epoxy resin (b-1) or the epoxy resin curing agent (b-2) can be used, but the solvent is used for the purpose of controlling the reaction rate and suppressing side reactions. It is preferable to use it. As a solvent to be used, methyl ethyl ketone, xylene, toluene, acetone, ethylene glycol monoethyl ether, cyclohexanone, ethyl ethoxypropionate, N, N-dimethylformamide, N, N-dimethylacetamide and the like can be used. These solvents may be used alone or in a mixed system. The ratio of this solvent to the resin composition for the auxiliary adhesion layer (B) may be a ratio that can be used as a varnish, and the use depends on the type of the polyfunctional epoxy resin (b-1) or the epoxy resin curing agent (b-2). Adjust the amount.
The conditions for the preliminary reaction are determined so as to adjust the molecular weight and melt viscosity of the target resin or the residual amount of the crystalline curing agent such as dicyandiamide. In general, the preliminary reaction is carried out in the range of 80 ° C. to 180 ° C. for about 30 minutes to 10 hours.
Moreover, a reaction accelerator can be used as needed during the preliminary reaction. Various imidazoles, phosphines, and BF ₃ amine complexes can be used as the reaction accelerator, but it is necessary to use a reaction accelerator that does not gel during the pre-reaction.

Furthermore, a reaction accelerator can be additionally used as necessary after the preliminary reaction. As the reaction accelerator at this time, various imidazoles and BF ₃ amine complexes which are latent thermosetting agents can be used.
Additional reaction accelerators used after the preliminary reaction are from the viewpoint of storage stability of insulating resin materials for wiring boards, handling properties of B-stage (semi-cured) insulating resin materials for wiring boards, and solder heat resistance. 2-phenylimidazole and 2-ethyl-4-methylimidazole are preferred. The blending amount is preferably 0.2 to 1.0 part by mass with respect to 100 parts by mass of the epoxy resin. By setting the amount to 0.2 parts by mass or more, the curing reaction is insufficient and the solder heat resistance is not lowered. By setting the amount to 1.0 parts by mass or less, the storage stability of the insulating resin material for wiring boards and B This is because the handleability of the stage-like insulating resin material for wiring boards is lowered.

  The crosslinked organic filler (b-3) in the adhesion auxiliary layer (B) may be any one as long as the average primary particle size is 1 μm or less. For example, as a copolymer of acrylonitrile butadiene, acrylonitrile and butadiene are used. Copolymerized crosslinked NBR particles, those obtained by copolymerizing acrylonitrile, butadiene and carboxylic acids such as acrylic acid, so-called core-shell rubber particles using polybutadiene, NBR, or silicon rubber as the core and acrylic acid derivatives as the shell can also be used. It is.

  The above-mentioned crosslinked NBR particles are those obtained by partially crosslinking and forming particles in a stage where acrylonitrile and butadiene are copolymerized and copolymerized. It is also possible to obtain carboxylic acid-modified crosslinked NBR particles by copolymerizing together carboxylic acids such as acrylic acid and methacrylic acid. The core-shell rubber particles of butadiene rubber-acrylic resin can be obtained by a two-stage polymerization method in which butadiene particles are polymerized by emulsion polymerization, and then monomers such as acrylic acid ester and acrylic acid are added to continue polymerization. The core-shell rubber particles of the crosslinked silicone rubber-acrylic resin can be obtained by a two-stage polymerization method in which the silicone particles are polymerized by emulsion polymerization, and then a monomer such as an acrylate ester or acrylic acid is added to continue the polymerization. The size of the particles can be 50 nm to 1 μm as the primary average particle size. These may be used alone or in combination of two or more.

Examples of commercially available carboxylic acid-modified acrylonitrile butadiene rubber particles include XER-91 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd., and core-shell particles of butadiene rubber-acrylic resin are Paraloid EXL2655 (commercial product) manufactured by Rohm and Haas Co., Ltd. Name) and AC-3832 (trade name) of Gantz Kasei Kogyo Co., Ltd.
Examples of the core-shell rubber particles of the crosslinked silicone rubber-acrylic resin include GENIOPERL P52 (trade name) manufactured by Asahi Kasei Wacker Silicone Co., Ltd.

In the adhesion auxiliary layer (B), the content of the crosslinked organic filler (b-3) is preferably 20 to 40% by mass. By setting the content of the crosslinked organic filler to 20% by mass or more, the toughness and elongation of the resin are high and a finer roughened shape can be obtained, so that the adhesive strength with the plated copper is improved. Moreover, heat resistance does not fall by content of a crosslinked organic filler being 40 mass% or less.
These crosslinked organic fillers (b-3) are preferably dispersed by a known kneading / dispersing method such as a kneader, a ball mill, a bead mill, a three-roll mill, or a nanomizer in order to enhance dispersibility.

Any fumed silica (b-4) used arbitrarily in the adhesion auxiliary layer (B) may be used, but in view of insulation reliability and heat resistance, dispersibility in the epoxy resin is good. For example, AEROSIL R972 (trade name) manufactured by Nippon Aerosil Co., Ltd. or AEROSIL R202 (trade name) manufactured by Nippon Aerosil Co., Ltd. can be used.
The content of fumed silica (b-4) is preferably in the range of 3 to 20% by mass in the solid content of the adhesion auxiliary layer (B) in order to improve the laser processability. When the fumed silica content is 3% by mass or more, the laser workability does not decrease and the auxiliary adhesion layer does not remain, and when the content is 20% by mass or less, the adhesive strength does not decrease.

  In addition to the components (A) to (D), various additives such as a thixotropic agent, a surfactant and a coupling agent used in ordinary insulating resin compositions are added to the auxiliary adhesion layer (B). It can mix | blend suitably. After sufficiently stirring these, it is allowed to stand until there are no bubbles to obtain a resin composition for an auxiliary adhesion layer.

When forming the adhesion auxiliary layer (B), it is preferable from the viewpoint of workability that the resin composition for the adhesion auxiliary layer is mixed in a solvent and diluted or dispersed to form a varnish. As this solvent, methyl ethyl ketone, xylene, toluene, acetone, ethylene glycol monoethyl ether, cyclohexanone, ethyl ethoxypropionate, N, N-dimethylformamide, N, N-dimethylacetamide and the like can be used. These solvents may be used alone or in a mixed system. The ratio of the solvent to the resin composition for the auxiliary adhesion layer is generally a ratio that can be used as a varnish, and the amount used is adjusted in accordance with the equipment for forming the coating film of the resin composition.
When the adhesive auxiliary layer (B) resin composition is applied to a carrier film (support) with a comma coater, the solvent content is adjusted so that the solid content of the resin composition excluding the solvent is 10 to 40% by mass in the varnish. It is preferable to adjust the amount used.
The thickness of the adhesion auxiliary layer (B) is 1 to 10 μm, preferably 2 to 5 μm. Adhesive strength is improved by setting the thickness of the auxiliary adhesion layer (B) to 1 μm or more, and by setting the thickness to 10 μm or less, it is effective for reducing the thermal expansion coefficient as an insulating resin for wiring boards.

The insulating resin material for wiring boards (additive insulating resin material) used for the multilayer wiring board of the buildup method of the present invention is, for example, a semi-cured film of the composition for the insulating resin layer (A) on the support Formed as.
That is, when an insulating resin film for additive is obtained as an example of the insulating resin material for wiring boards, first, the varnish of the composition for the adhesion auxiliary layer (B) is applied and dried on the support, and then the adhesion auxiliary layer. There is a method in which an attached support is prepared, a varnish of the composition for an insulating resin layer (A) is applied on the adhesion auxiliary layer of the obtained support, and dried.
When applying the varnish of the composition for the insulating resin layer (A) onto the support with an adhesion auxiliary layer, a comma coater, a bar coater, a kiss coater, a roll coater, or the like can be used, and it is appropriately used depending on the thickness of the additive insulating film. The coating thickness, drying conditions after coating, and the like are not particularly limited because they are appropriately selected according to the purpose of use, but it is generally preferred that the solvent used in the varnish is volatilized by 80% by mass or more.
Examples of the support on which the insulating resin film for additive is formed include a plastic film such as PET, a metal foil, and the like. When the support is peeled off after the additive insulating resin film is cured, a releasable plastic is used. A film or the like is preferable.

In the multilayer wiring board of the present invention, an insulating layer and an outer circuit layer are sequentially laminated on one or both sides of a substrate having an inner layer circuit, and the insulating resin material for the wiring board of the present invention is a cured product. It is characterized by being. Insulating resin materials for wiring boards are usually cured by a thermal history during the production of multilayer wiring boards.
Hereinafter, the manufacturing method of the multilayer wiring board of this invention is demonstrated using drawing. FIG. 1 is a cross-sectional view for explaining an example of a process for producing a multilayer wiring board of the present invention.
The multilayer wiring board of the present invention comprises a step (a) of laminating an insulating resin material for a wiring board, a step (b) of obtaining an insulating layer by curing the insulating resin material for the wiring board, and an outer layer circuit layer on the surface of the insulating layer. It is manufactured in multiple layers by repeating the forming step (c).

FIG. 1A is a cross-sectional view of a circuit board used for manufacturing a multilayer wiring board according to the present invention, and a first circuit 1 (inner layer wiring) is formed on an insulating substrate 2.
As the inner layer substrate, known laminates used in ordinary wiring boards, for example, glass cloth-epoxy resin, paper-phenol resin, paper-epoxy resin, glass cloth / glass paper-epoxy resin, etc. can be used. There is no. Further, a BT substrate impregnated with a bismaleimide-triazine resin, a polyimide film substrate using a polyimide film as a base material, and the like can also be used.
The method for forming the first circuit 1 is not particularly limited, and uses a copper-clad laminate in which a copper foil and the insulating substrate are bonded to each other. A known method for manufacturing a wiring board, such as an additive method for forming a circuit by electroless plating at a necessary portion of a substrate, can be used.
Although FIG. 1A shows an example in which the first circuit 1 is formed on one side of the insulating substrate 2, the circuit 1 can also be formed on both sides of the insulating substrate 2 using a double-sided copper-clad laminate. .
The first circuit 1 performs a surface treatment on the surface of the circuit 1 in a state suitable for adhesiveness as necessary. This technique is not particularly limited. For example, a copper oxide needle crystal is formed on the surface of the first circuit 1 with an alkaline aqueous solution of sodium hypochlorite, and the formed copper oxide needle crystal is converted to dimethylamine borane. A known production method such as immersion in an aqueous solution for reduction can be used.

(1) Step of laminating insulating resin material for wiring board (a)
First, an insulating resin layer 4 with an adhesion auxiliary layer 3 is formed by laminating the insulating resin material for a wiring board of the present invention on one or both sides of a circuit board having the first circuit 1 [see FIG. ]. In FIG. 1B, the first circuit 1 is formed on one side of the circuit board, but may be formed on both sides. In this case, the insulating resin layer 4 can be formed on both sides of the circuit board. There is no restriction | limiting in particular in this formation method, For example, the method of laminating | stacking and forming the said insulating resin film for additive on a circuit board is mentioned.

  In the case of using an additive insulating resin film having an adhesion auxiliary layer with a support, examples of the support on which the varnish is applied include a plastic film such as PET, and a mold release when the support is peeled off after the varnish is cured. A plastic film or the like is preferable. The additive insulating resin film having the support auxiliary adhesion layer is laminated on the circuit board by using a laminating method or a pressing device with the insulating resin layer (A) facing the surface of the circuit board in contact with the circuit layer.

(2) Step of curing the insulating resin material for wiring boards to obtain an insulating layer (b)
Next, the laminated insulating resin material for wiring boards is heated and cured to form an insulating layer composed of the first adhesion auxiliary layer 3 and the insulating resin layer 4 (see FIG. 1B).
It is necessary to perform the curing temperature at a temperature and time considering the subsequent plating process and copper annealing process. That is, if the curing is advanced too much, the adhesiveness with copper is lowered during the subsequent plating process, and if the curing is not sufficient, a phenomenon may occur in which it is eroded by the alkaline treatment solution during the plating treatment and dissolved in the plating solution. Considering these, it is desirable to cure by applying a heat treatment at 150 to 190 ° C. for 30 to 90 minutes. When the additive insulating resin film having the support auxiliary layer with the support is used, the pressure lamination step and the heat curing step may be performed simultaneously or separately. The pressurization lamination conditions may be as long as the unevenness of the first circuit 1 is embedded in the insulating resin material for a wiring board in a semi-cured state, and usually 0.5 to 20 MPa is preferable.
Note that via holes may be formed in the first adhesion auxiliary layer 3 and the insulating material resin layer 4 in order to connect the first circuit 1 which is the inner layer circuit and the outer layer circuit to each other [see FIG. 1B]. There is no restriction | limiting in particular as a formation method of this via hole, A laser method, a sandblasting method, etc. can be used.

(3) Step of forming an outer circuit layer on the surface of the insulating layer (c)
Thereafter, the second circuit 5 is formed by performing the following circuit processing, and further, an interlayer connection between the first circuit 1 and the second circuit is formed [see FIG. 1C].
First, when forming the 2nd circuit 5 which is an outer layer circuit on the adhesion auxiliary layer 3 by a plating method, it is preferable to roughen the adhesion auxiliary layer 3. As the roughening liquid, an oxidizing roughening liquid such as a chromium / sulfuric acid roughening liquid, an alkaline permanganic acid roughening liquid, a sodium fluoride / chromium / sulfuric acid roughening liquid, or a borofluoric acid roughening liquid can be used. As the roughening treatment, for example, first, an aqueous solution of diethylene glycol monobutyl ether and NaOH is heated to 70 ° C. as a swelling solution, and the adhesion auxiliary layer 3 is immersed for 5 minutes. Next, as a roughening liquid, an aqueous solution of KMnO ₄ and NaOH is heated to 80 ° C. and immersed for 10 minutes. Subsequently, it is neutralized by immersing it in a neutralizing solution, for example, an aqueous hydrochloric acid solution of stannous chloride (SnCl ₂ ) at room temperature for 5 minutes.
Thereby, the surface roughness (Ra) of the adhesion auxiliary layer (B) after the roughening treatment is 0.3 μm or less, and a very fine and dense roughened shape is obtained.

After the roughening treatment, a plating catalyst applying treatment for attaching palladium is performed. Plating catalyst treatment
It is performed by immersing in a palladium chloride plating catalyst solution. Next, an electroless plating layer (conductor layer) having a thickness of 0.3 to 1.5 μm is formed on the entire surface of the auxiliary adhesion layer 3 by immersion in an electroless plating solution (including the inner surface of the via hole when a via hole is formed). To precipitate. If necessary, further electroplating is performed to obtain a necessary thickness.
As the electroless plating solution used for electroless plating, a known electroless plating solution can be used, and there is no particular limitation. Also, electroplating can be performed by a known method and is not particularly limited. These platings are preferably copper platings. Furthermore, unnecessary portions can be removed by etching to form the second circuit 5 and the interlayer connection between the first circuit 1 and the second circuit 5.

A wiring board having the first circuit 1 and the second circuit 5 is manufactured through the above steps (A), (B), and (C). The surface treatment of the second circuit 5 is performed in the same manner as the surface treatment, and the adhesion assisting layer 6 and the insulating resin layer 7 are formed in the same manner as the formation of the adhesion assisting layer 3 and the insulating resin layer 4 [FIG. )reference].
That is, the laminated insulating resin material for wiring boards is cured to form the second adhesion auxiliary layer 6 and the insulating resin layer 7, and a via hole is formed [see FIG. 1 (d)]. Further, the third circuit layer 8 is formed in the same manner [see FIG. 1 (e)].
Thereafter, a multilayer wiring board having a large number of layers can be produced by repeating the same process.

Next, the present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention.
The performance of the insulating resin material for wiring boards and multilayer wiring boards produced in the following examples was measured and evaluated by the following methods.

(1) Adhesive strength with outer layer circuit A part of the outermost layer circuit (third circuit) of the multilayer wiring board obtained in each example and comparative example is 10 mm wide and 100 mm long by etching copper. This one end was peeled off at the circuit / resin interface and held with a gripper, and the load when peeled off at room temperature at a pulling speed of about 50 mm / min in the vertical direction was measured.

(2) Surface roughness (Ra) of the auxiliary adhesion layer
The copper of the outermost layer circuit (third circuit) of the multilayer wiring board obtained in each example and comparative example was etched, and the exposed surface of the adhesion auxiliary layer was micro-map MN5000 manufactured by Ryoka Systems Co., Ltd. Using a mold, the surface roughness Ra (μm) was measured.

(3) Coefficient of thermal expansion The insulating resin material for a wiring board (additive insulating resin film) obtained in each of the examples and comparative examples was applied to the roughened surface of a copper foil (YGP-12, trade name, manufactured by Nihon Electrolytic Co., Ltd.) Lamination was performed using a batch type vacuum pressure laminator MVLP-500 (trade name, manufactured by Meiki Co., Ltd.). Next, after peeling off the PET film, a cured film is produced under the curing conditions of 180 ° C.-60 minutes, and the copper foil is etched away with an ammonium persulfate solution, then washed with water and dried at 80 ° C. for 10 minutes to obtain a cured film. Obtained.
The obtained cured film was heated to 240 ° C. at 10 ° C./min using a sample with a width of 3 mm and a gap between 8 mm using a thermal strain analyzer manufactured by SII, and cooled to −10 to 10 ° C./min. The coefficient of thermal expansion of 0 to 150 ° C. was determined from the change curve of the amount of expansion when the temperature was raised to 300 ° C.

(4) 288 ° C. Solder heat resistance The multilayer wiring boards produced in each Example and Comparative Example were cut into 25 mm squares, floated in a solder bath adjusted to 288 ± 2 ° C., and the time until blistering was examined.

(5) Laser workability In each example and comparative example, (5) Preparation of multilayer wiring board (2) The substrate before plating in (2) is observed with a scanning electron microscope (SEM), and the presence or absence of foreign matters such as residual resin is evaluated. did.

(6) Highly accelerated life test (HAST test)
In each of the examples and comparative examples, a wiring board having a comb-type circuit with a line / space of 10/10 μm was prepared, and a maximum of 200 at 130 ° C., 85% RH, and an applied voltage of 5.5 V in an unsaturated pre-shear cooker tank. A time energization test was conducted.

Example 1
(1) Production of inner layer circuit board Glass cloth base epoxy resin double-sided copper-clad laminate [MCL-E-679FG (trade name) manufactured by Hitachi Chemical Co., Ltd., copper foil thickness 18 μm, substrate thickness 0.4 mm, double-sided Has roughened foil on both sides. ] Was etched on one side to produce a circuit board having a circuit (hereinafter referred to as a first circuit) on one side.

(2) Production of support with adhesion auxiliary layer 100 parts by mass of polyfunctional epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: NC-3000H), 1.3 parts by mass of epoxy resin curing agent (dicyandiamide), reaction accelerator 0.2 parts by mass (manufactured by Shikoku Kasei Co., Ltd., 2-phenylimidazole) and 65 parts by mass of solvent (cyclohexanone) were blended in a flask and pre-reacted at 130 ° C. for 2 hours. The polystyrene-reduced weight molecular weight measured by gel permeation liquid chromatography (GPC) after the reaction was 2,330.
After cooling, 50 parts by weight of a curing agent (manufactured by DIC Corporation, trade name: LA-3018, solid content 50% by weight), 55 parts by weight of a crosslinked organic filler (Paraloid EXL2655, trade name, manufactured by Rohm and Haas Japan Co., Ltd.) , Fumed silica (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil R-972) 15 parts by mass, curing accelerator (manufactured by Shikoku Chemicals Co., Ltd., 2-ethyl-4-methylimidazole) 0.5 part by mass, solvent 250 parts by mass of (2-butanone) and 200 parts by mass of cyclohexanone were mixed with a stirring rod, and a uniform varnish was obtained using a disperser (trade name: Nanomizer, manufactured by Yoshida Kikai Kogyo Co., Ltd.). This varnish was applied to a release-treated surface of a release-treated polyethylene terephthalate (PET) film (product name: PET-38X, manufactured by Lintec Corporation) so as to be 5 μm after drying, and dried at 140 ° C. for 10 minutes. .

(3) Production of insulating resin material for wiring board (insulating resin film for additive) 125 parts by mass of a polyfunctional epoxy resin (manufactured by DIC Corporation, trade name: N-673-80M, solid content 80% by mass), bismaleimide compound (Daiwa Kasei Co., Ltd., trade name: BMI-2300) 114 parts by mass, p-aminophenol 10 parts by mass and 2-methoxyethanol 45 parts by mass, modified bismaleimide obtained by reacting at 125 ° C. for 2 hours 190 parts by mass of compound (solid content 65%), epoxy resin curing agent (manufactured by DIC Corporation, trade name: LA-3018, solid content 50% by weight), 10 parts by mass, phosphorus flame retardant (HCA-HQ: trade name) , Sanko Co., Ltd.) 40 parts by mass, inorganic filler (spherical silica) (manufactured by Admatechs, trade name: SO-C2) 155 parts by mass, curing accelerator (2 -Ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd.) 0.5 parts by mass and 70 parts by mass of solvent (2-butanone) are mixed uniformly, and a disperser (Yoshida Kikai Kogyo Co., Ltd., trade name: Nanomizer) Was used to obtain a uniform varnish.
This varnish was applied to the adhesion assisting layer side of the support with the adhesion assisting layer obtained in the previous section so as to be 35 μm after drying, dried at 100 ° C. for 5 minutes, and the intended insulating resin material for wiring boards (additive) Insulating resin film) was obtained.

(4) Fabrication of multilayer wiring board (1)
Batch type vacuum pressurization laminator MVLP-500 (named with the insulating resin material for wiring board (insulating resin film for additive)) and the inner layer circuit board, with the insulating resin layer facing the first circuit layer of the circuit board (Trade name, manufactured by Kikai Co., Ltd.). Next, after peeling off the PET film, the insulating resin material for wiring boards was cured under curing conditions of 180 ° C.-60 minutes to obtain a first insulating layer composed of the adhesion auxiliary layer 3 and the insulating resin layer 4.
A via hole for interlayer connection is processed in this first insulating layer using a Hitachi Via Mechanics CO ₂ laser processing machine (LCO-1B21 type) under the conditions of a beam diameter of 60 μm, a frequency of 500 Hz, a pulse width of 5 μsec, and a shot number of 4. And made. In order to chemically roughen the first adhesion assisting layer 3, an aqueous solution of diethylene glycol monobutyl ether: 200 ml / L, NaOH: 5 g / L was prepared as a swelling liquid, heated to 80 ° C. and immersed for 3 minutes.
Next, an aqueous solution of KMnO ₄ : 60 g / L and NaOH: 40 g / L was prepared as a roughening solution, heated to 80 ° C. and immersed for 5 minutes. Subsequently, it was neutralized by immersing it in an aqueous solution of a neutralizing solution (SnCl ₂ : 30 g / L, HCl: 300 ml / L) at room temperature (25 ° C.) for 5 minutes.

In order to form the second circuit layer on the surface of the first adhesion assisting layer 3, first, an electroless plating catalyst solution containing PdCl ₂ (trade name: HS-202B, manufactured by Hitachi Chemical Co., Ltd.) Immersion treatment at room temperature (25 ° C.)-10 minutes, washed with water, immersed in a plating solution for electroless copper plating (trade name: CUST-201, manufactured by Hitachi Chemical Co., Ltd.) for 15 minutes at room temperature, gave.
Furthermore, a 15 μm thick plating resist (manufactured by Hitachi Chemical Co., Ltd., trade name: RD-1215) is laminated, exposed using a negative mask and a light source of 405 nm under the condition of 120 mJ / cm 2, and a 1% sodium carbonate aqueous solution is used. Development was performed, and plating with a thickness of 8 μm was performed by copper sulfate electrolytic plating.
Thereafter, the resist is stripped using a 3% aqueous sodium hydroxide solution, unnecessary power feeding layer (electroless plating layer) is removed by etching using a sulfuric acid-hydrogen peroxide aqueous solution, and the permanganic acid roughening solution is used. Then, unnecessary palladium was removed, and a second circuit including a via hole connected to the first circuit layer was formed.
Further, in order to make a multilayer, the second circuit conductor surface was immersed in an aqueous solution of sodium chlorite: 50 g / liter, NaOH: 20 g / liter, trisodium phosphate: 10 g / liter at 85 ° C. for 20 minutes, Washed with water and dried at 80 ° C. for 20 minutes to form copper oxide irregularities on the surface of the second circuit conductor.

(5) Fabrication of multilayer wiring board (2)
The step (4) was repeated to produce a three-layer multilayer wiring board. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

Example 2
In preparation of the support body with the adhesion auxiliary layer of Example 1 (2), the same procedure as in Example 1 was performed except that 35 mass parts of the paraloid EXL2655 of the crosslinked organic filler was used and the thickness of the adhesion auxiliary layer was 9 μm. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

Example 3
In the production of the support with an adhesion auxiliary layer in Example 1 (2), as the cross-linked organic filler, Staphyloid AC-3832 (manufactured by Ganz Kasei Co., Ltd., trade name) is 80 parts by mass, and the thickness of the adhesion auxiliary layer is 3 μm. The procedure was the same as in Example 1 except that. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

Example 4
Example 3 (3) In production of insulating resin material for wiring board (insulating resin film for additive), except that phosphorus flame retardant (manufactured by Sanko Co., Ltd., trade name: HAC-HQ) was changed to 60 parts by mass. Same as Example 1. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

Comparative Example 1
In Example 1, it carried out similarly to Example 1 except having formed the insulating resin layer, without forming an adhesion auxiliary layer. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

Comparative Example 2
In the production of the support with an adhesion auxiliary layer in Example 1 (2), the same procedure as in Example 1 was carried out except that the preliminary reaction was not carried out and all the ingredients were mixed and mixed. Table 1 shows the measurement and evaluation results of the performance of the obtained multilayer wiring board.

From Table 1, the multilayer wiring board using the insulating resin material for wiring boards of the present invention shows electroless copper plating and high adhesion on a smooth resin surface, as is apparent from Examples 1-4. Moreover, it shows a good result that the laser workability and the HAST test are excellent with a low coefficient of thermal expansion. Furthermore, it is excellent also in 288 degreeC solder heat resistance, and it is possible to manufacture the multilayer wiring board in consideration of the environment.
On the other hand, the multilayer wiring boards shown in Comparative Examples 1 and 2 that do not use the insulating resin material for wiring boards according to the present invention have large surface roughness, or malfunctions occurred in laser processability and HAST tests.

According to the present invention, in a multilayer wiring board of a build-up system, even a smooth resin surface exhibits high adhesion with electroless plating, has a low thermal expansion coefficient, excellent workability and heat resistance, and can form fine circuits. It is possible to provide a highly reliable multilayer wiring board that can be made lead-free and to provide an insulating resin material for wiring boards having high solder heat resistance.
Therefore, by using the insulating resin material for a wiring board of the present invention, a highly integrated multilayer wiring board can be advantageously manufactured, and downsizing, weight reduction, and multifunctionalization of electronic devices are promoted.

1 First circuit 2 Substrate (insulating substrate)
3 Adhesion auxiliary layer 4 Insulating resin layer 5 Second circuit 6 Adhesion auxiliary layer (second layer)
7 Insulating resin layer 8 Third circuit

Claims (9)

It has an insulating resin layer (A) and an adhesion auxiliary layer (B). The insulating resin layer (A) is composed of a polyfunctional epoxy resin (a-1), a bismaleimide compound (a-2), an epoxy resin curing agent ( a-3) and an inorganic filler (a-4) containing layer, the adhesion auxiliary layer (B) is a preliminary reaction between the polyfunctional epoxy resin (b-1) and the epoxy resin curing agent (b-2) A product and a varnish formed by mixing a crosslinked organic filler (b-3) having an average primary particle size of 1 μm or less are coated and then dried to form a layer having a thickness of 1 to 10 μm . Insulating resin material for wiring boards that does not contain glass cloth .   The insulating resin material for wiring boards according to claim 1, wherein the insulating resin layer (A) further contains a phosphorus-based flame retardant (a-5).   The insulating resin material for wiring boards according to claim 1 or 2, wherein the adhesion auxiliary layer (B) further contains fumed silica (b-4).   The insulating resin material for wiring boards according to any one of claims 1 to 3, wherein the crosslinked organic filler (b-3) contained in the adhesion auxiliary layer (B) is a core-shell structured crosslinked rubber particle.   The insulating resin material for wiring boards according to any one of claims 1 to 4, wherein the content of the crosslinked organic filler (b-3) based on solid content in the adhesion auxiliary layer (B) is 20 to 40% by mass.   The multifunctional epoxy resin (b-1) in the adhesion auxiliary layer (B) is an aralkyl epoxy resin having a biphenyl structure, and the epoxy resin curing agent (b-2) is a triazine ring-containing novolac phenol resin and / or dicyandiamide The insulating resin material for wiring boards according to any one of claims 1 to 5.   The surface roughness (Ra) of the adhesion auxiliary layer (B) after curing and roughening the insulating resin material for a wiring board is 0.3 μm or less, for a wiring board according to claim 1. Insulating resin material.   An insulating resin material for a wiring board according to any one of claims 1 to 7, wherein the insulating layer and the outer layer circuit layer are sequentially laminated on one or both sides of a substrate having an inner layer circuit, wherein the insulating layer is the insulating resin material for a wiring board according to any one of claims 1 to 7. A multilayer wiring board characterized by being a cured product.   A step (a) of laminating the insulating resin material for wiring boards according to any one of claims 1 to 7 on a substrate having an inner layer circuit, and a step (b) of obtaining an insulating layer by curing the insulating resin material for wiring boards. A method for producing a multilayer wiring board comprising the step (c) of forming an outer circuit layer on the surface of the insulating layer.

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