JP6232747B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

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

  Multilayer printed wiring boards are widely used in various electronic devices and electronic parts. As a technique for manufacturing a multilayer printed wiring board, a manufacturing method by a built-up method in which insulating layers and conductor layers are alternately stacked on an inner circuit board provided with circuit conductors is known.

  The manufacturing method by the build-up method is generally performed according to the following procedure. First, a resin composition layer is provided on an inner layer circuit board, and the resin composition layer is cured to form an insulating layer. Next, the surface of the insulating layer is swollen with a swelling liquid and then roughened with an oxidizing agent to form minute irregularities on the surface of the insulating layer. Thereafter, a conductor layer having a predetermined wiring pattern is formed on the surface of the insulating layer according to a known method such as a semi-additive method.

  In recent years, when manufacturing a multilayer printed wiring board, an inorganic filler is used as a resin composition for forming an insulating layer in order to prevent delamination and circuit distortion due to a difference in thermal expansion between the insulating layer and the conductor layer. Tends to be blended at a high blending amount (Patent Document 1).

JP 2010-202865 A

  Due to the recent needs for miniaturization of electronic devices and electronic parts, multilayer printed wiring boards tend to be made thinner and thinner, and it is required to make the insulating layer thinner. However, when the insulating layer becomes thinner, a decrease in insulation reliability of the insulating layer becomes a new problem.

  The subject of this invention is providing the manufacturing method of the multilayer printed wiring board which is excellent in insulation reliability, even when the thickness of an insulating layer is thin.

  In the process of earnestly studying the above problems, the inventors of the present invention, in the production of a multilayer printed wiring board, the insulating reliability of the insulating layer is a swelling step for swelling the insulating layer surface with a swelling liquid and the insulating layer surface with an oxidizing agent. It has been found that it is greatly influenced by the conditions of the roughening step for roughening. In particular, 1) When the thickness of the insulating layer on the circuit conductor is 15 μm or less as a result of thinning the multilayer printed wiring board, 2) the inorganic filler content is high in order to reduce the coefficient of thermal expansion (for example, It has been found that when the insulating layer is formed using the resin composition (50% by mass or more), the influence of the swelling step and the roughening step becomes significant, and the insulation reliability of the insulating layer is likely to be lowered.

  And as a result of proceeding with the study based on the above knowledge, the present inventors set the mass increase per unit area of the insulating layer in the swelling process and the mass decrease per unit area of the insulating layer in the roughening process to a certain value or less. In addition, by performing the swelling step and the roughening step so that the mass decrease amount in the roughening step is larger than the mass increase amount in the swelling step, good insulation reliability can be obtained even when the insulating layer is thin. As a result, the present invention was completed.

That is, the present invention includes the following contents.
[1] A method for producing a multilayer printed wiring board, comprising: (I) a step of swelling an insulating layer formed on an inner layer circuit board with a swelling liquid; and (II) a step of roughening the surface of the insulating layer with an oxidizing agent. Thus, the mass increase amount (M1) per unit area of the insulating layer in step (I) is 0.30 mg / cm ² or less, and the mass reduction amount (M2) per unit area of the insulating layer in step (II) is 0.00. 40 mg / cm ² or less, and M1 and M2 satisfy the relationship of M1 ≦ M2, a method for manufacturing a multilayer printed circuit board.
[2] The method according to [1], wherein M1 and M2 satisfy a relationship of M1 <M2.
[3] The method according to [1], wherein M1 and M2 satisfy a relationship of M1 + 0.05 <M2.
[4] The method according to any one of [1] to [3], wherein the thickness of the insulating layer formed on the inner circuit board on the circuit conductor is 15 μm or less.
[5] The method according to any one of [1] to [3], wherein the thickness of the insulating layer formed on the inner circuit board on the circuit conductor is 1 μm or more and 15 μm or less.
[6] The method according to any one of [1] to [5], wherein the insulating layer is formed by thermosetting the resin composition layer.
[7] The content of the inorganic filler in the resin composition is 50% by mass or more when the nonvolatile component in the resin composition constituting the resin composition layer is 100% by mass. Method.
[8] When the nonvolatile component in the resin composition constituting the resin composition layer is 100 mass%, the content of the inorganic filler in the resin composition is 50 mass% or more and 90 mass% or less, [6 ] The method of description.
[9] The method according to [7] or [8], wherein the resin composition further comprises an epoxy resin and a curing agent.
[10] The method according to any one of [1] to [9], wherein after step (II), the arithmetic average roughness (Ra) of the insulating layer surface is 400 nm or less.
[11] The method according to any one of [1] to [10], wherein after step (II), the arithmetic average roughness (Ra) of the insulating layer surface is 300 nm or less.
[12] The method according to any one of [1] to [11], wherein after step (II), the arithmetic average roughness (Ra) of the surface of the insulating layer is 200 nm or less.
[13] The method according to any one of [1] to [12], which comprises the following steps (A), (B) and (C) before step (I).
(A) A step of laminating a resin sheet including a support film and a resin composition layer provided on the support film to an inner circuit board so that the resin composition layer is bonded to the inner circuit board. (B) Resin Step of thermally curing the composition layer to form an insulating layer (C) Step of drilling the insulating layer to form a via hole [14] After step (II), the following steps (D) and (E) are included , [1] to [13].
(D) Step of neutralizing the surface of the insulating layer with a neutralizing solution (E) Step of forming a conductor layer by plating on the surface of the insulating layer

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the thickness of an insulating layer is thin, the manufacturing method of the multilayer printed wiring board excellent in insulation reliability can be provided.

  According to the method for producing a multilayer printed wiring board of the present invention, for example, 1) When the thickness of the insulating layer on the circuit conductor is 15 μm or less, 2) The inorganic filler content is high (for example, 50% by mass or more) ) Even when an insulating layer is formed using a resin composition, a multilayer printed wiring board excellent in insulation reliability can be realized.

  Furthermore, according to the manufacturing method of the multilayer printed wiring board of this invention, the effect that the roughness of the surface of an insulating layer can be restrained low is brought about simultaneously.

  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 includes (I) a step of swelling an insulating layer formed on an inner layer circuit board with a swelling liquid, and (II) a step of roughening the surface of the insulating layer with an oxidizing agent. The mass increase amount (M1) per unit area of the insulating layer in step (I) is 0.30 mg / cm ² or less, and the mass reduction amount (M2) per unit area of the insulating layer in step (II) is 0.40 mg. / cm ² or less, and M1 and M2 satisfy the relationship of M1 ≦ M2.

  By performing the swelling step of step (I) and the roughening step of step (II) under the above-mentioned specific conditions, the inventors have achieved insulation reliability even when the insulating layer is thin. It has been found that a multilayer printed wiring board having excellent resistance can be realized.

From the viewpoint of the insulation reliability of the insulating layer, the mass increase amount (M1) per unit area of the insulating layer in the step (I) is 0.30 mg / cm ² or less, preferably 0.25 mg / cm ² or less, preferably 0.20 mg / cm ² or less, even more preferably 0.15 mg / cm ² or less. When the increase in mass (M1) exceeds 0.30 mg / cm ² , especially 1) When the insulating layer on the circuit conductor is thin 2) Insulate using a resin composition with a high inorganic filler content When forming a layer, etc., the insulation reliability tends to decrease significantly. Although the minimum of mass increase (M1) is not specifically limited, Usually, it is 0.02 mg / cm < ² > or more. If the swelling is insufficient, the surface of the insulating layer in the subsequent roughening step (that is, step (II)) tends to be insufficiently roughened, and the adhesion strength of the conductor layer formed on the surface of the insulating layer tends to decrease. It is in. The mass increase amount (M1) can be measured according to the description of <Measurement of mass increase amount (M1) per unit area of insulating layer in the swelling step> below.

From the viewpoint of the insulation reliability of the insulating layer, weight loss per insulating layer unit area in the step (II) (M2) is a 0.40 mg / cm ² or less, preferably 0.35 mg / cm ² or less, further Preferably it is 0.30 mg / cm ² or less. When the mass loss (M2) exceeds 0.40 mg / cm ² , especially 1) When the insulating layer on the circuit conductor is thin 2) Insulate using a resin composition with a high content of inorganic filler When forming a layer, etc., the insulation reliability tends to decrease significantly. The lower limit of the mass reduction amount (M2) is not particularly limited, but is usually 0.05 mg / cm ² or more. If the roughening is insufficient, the adhesion strength of the conductor layer formed on the surface of the insulating layer tends to decrease. By setting the value of mass reduction amount (M2) within the above range, the conductor layer can be formed on the surface of the insulating layer with sufficient adhesion strength while keeping the roughness of the surface of the insulating layer low. Can contribute significantly. The mass reduction amount (M2) can be measured in accordance with the description in <Measurement of mass reduction amount (M2) per unit area of insulating layer in the roughening step> below.

  From the viewpoint of the insulation reliability of the insulating layer, the mass increase amount (M1) per unit area of the insulating layer in the step (I) and the mass reduction amount (M2) per unit area of the insulating layer in the step (II) are M1 ≦ It is important to satisfy the relationship of M2. In the case of M1> M2, particularly when 1) the thickness of the insulating layer on the circuit conductor is thin, 2) when the insulating layer is formed using a resin composition having a high inorganic filler content, etc. The decrease in reliability tends to be remarkable. From the viewpoint of further increasing the insulation reliability of the insulating layer and suppressing the roughness of the insulating layer surface, the mass increase amount (M1) and the mass decrease amount (M2) are preferably in a relationship of M1 + 0.05 <M2. More preferably, the relationship of M1 + 0.10 <M2 is satisfied.

  Hereinafter, process (I) and process (II) are demonstrated.

<Process (I)>
In step (I), the insulating layer formed on the inner layer circuit board is swollen with a swelling liquid.

  The step (I) is not particularly limited as long as the amount of mass increase (M1) per unit area of the insulating layer falls within the specific range, and any conventionally known arbitrary method can be used for swelling the surface of the insulating layer in the production of the multilayer printed wiring board. It may be implemented in the procedure.

  In a preferred embodiment, in the step (I), the surface of the insulating layer formed on the inner layer circuit board is subjected to 5 to 20 minutes (preferably 8 to 15 minutes) at 50 to 80 ° C. (preferably 55 to 70 ° C.). ), Soaking in a swelling solution.

  Examples of the swelling liquid used in the step (I) include an alkaline solution and a surfactant solution, and an alkaline solution is preferable. Examples of the alkaline solution include a solution containing an alkali metal hydroxide, and specific examples include a sodium hydroxide solution and a potassium hydroxide solution. A swelling liquid may be used individually by 1 type or in combination of 2 or more types.

  A commercial product may be used as the swelling liquid. Examples of commercially available swelling liquids include “Circuposit MLB211” and “Cuposit Z” manufactured by Rohm & Haas Electronic Materials Co., Ltd., and “Swelling Dip Securigans P” manufactured by Atotech Japan Co., Ltd. Dip Securiganth P) "and" Swelling Dip Securiganth SBU ". These may be used in combination of two or more.

  The degree of swelling of the insulating layer in step (I) (that is, the amount of increase in mass per unit area of the insulating layer (M1)) depends on the temperature and time during the swelling treatment, and the type of swelling liquid, depending on the composition of the resin composition It can control by adjusting etc. The resin composition used for forming the insulating layer will be described later.

  When the insulating layer has a via hole, it is preferable to carry out a water washing treatment after the step (I) from the viewpoint of maintaining a good shape of the via hole. Therefore, in a preferred embodiment, the method for producing a multilayer printed wiring board of the present invention includes a step of washing the insulating layer between steps (I) and (II).

<Process (II)>
In step (II), the surface of the insulating layer is roughened with an oxidizing agent.

  The step (II) is not particularly limited as long as the amount of mass reduction (M2) per unit area of the insulating layer falls within the specific range described above, and any conventionally known option may be used for roughening the surface of the insulating layer in the production of a multilayer printed wiring board. You may carry out in the procedure of.

  In a preferred embodiment, in the step (II), the surface of the insulating layer is immersed in an oxidizing agent at 60 to 80 ° C. (preferably 70 to 80 ° C.) for 10 to 30 minutes (preferably 15 to 25 minutes). To implement.

  Examples of the oxidizing agent used in the step (II) include an alkaline permanganate solution obtained by dissolving a permanganate (eg, potassium permanganate, sodium permanganate) in a sodium hydroxide aqueous solution, and a dichromate. (For example, potassium dichromate), ozone, hydrogen peroxide, sulfuric acid, hydrogen peroxide / sulfuric acid, nitric acid and the like, and alkaline permanganate solution is preferable. The concentration of permanganate in the alkaline permanganate solution is preferably 5 to 10% by mass. You may use an oxidizing agent individually by 1 type or in combination of 2 or more types.

  A commercially available product may be used as the oxidizing agent. Commercially available oxidizers include, for example, “Circuposit MLB213A-1” and “Circuposit MLB213B-1” manufactured by Rohm & Haas Electronic Materials Co., Ltd., “Concentrate Compact CP” manufactured by Atotech Japan Co., Ltd. And alkaline permanganate solution such as “Dosing Solution Securigans P”. These may be used in combination of two or more.

  The degree of roughening of the insulating layer in step (II) (that is, the amount of mass reduction per unit area of the insulating layer (M2)) depends on the temperature and time during the roughening treatment, the oxidizing agent, depending on the composition of the resin composition. It can be controlled by adjusting the type of the above. The degree of roughening of the insulating layer in step (II) can also be controlled by adjusting the content of the roughening component in the resin composition. For example, when the content of roughening components such as thermoplastic resin and rubber particles is increased, the degree of roughening tends to increase. The degree of roughening can also be adjusted by adjusting the type and content of the epoxy resin and curing agent in the resin composition. For example, when an epoxy resin having a high content of liquid epoxy resin is used as the epoxy resin, the degree of roughening tends to increase. Further, when a phenolic curing agent is used as the curing agent, the degree of roughening tends to increase, and when an active ester curing agent is used, the degree of roughening tends to decrease.

  By performing step (I) and step (II), irregularities are formed on the surface of the insulating layer formed on the inner circuit board. In general, when the roughness of the surface of the insulating layer is large, the adhesion strength of the conductor layer formed on the surface of the insulating layer tends to increase due to the anchor effect. In this regard, according to the method for producing a multilayer printed wiring board of the present invention in which the step (I) and the step (II) are performed under specific conditions, an insulating layer having a low surface roughness is provided in a range that provides sufficient adhesion strength. Can bring.

In the method for producing a multilayer printed wiring board of the present invention, after step (II), the arithmetic average roughness (Ra) of the surface of the insulating layer is preferably 400 nm or less, more preferably 300 nm or less, still more preferably 200 nm or less, Even more preferably, it is 150 nm or less or 100 nm or less. The lower limit of the Ra value is preferably 10 nm or more, more preferably 20 nm or more, from the viewpoint of obtaining sufficient adhesion strength.
The arithmetic average roughness (Ra) of the insulating layer 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 NT3300” manufactured by Bee Coins Instruments can be cited.

  Hereinafter, the inner layer circuit board and the insulating layer will be described.

  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 dimension of the circuit conductor provided in the inner layer circuit board may be determined according to desired characteristics. For example, the thickness of the circuit conductor is preferably 40 μm or less, more preferably 35 μm or less, still more preferably 30 μm or less, even more preferably 25 μm or less, particularly preferably 20 μm or less, from the viewpoint of thinning the multilayer printed wiring board. 19 μm or less, or 18 μm or less. The lower limit of the thickness of the circuit conductor is not particularly limited, but is usually 1 μm or more, 3 μm or more, 5 μm or more, and the like.

  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 resin composition layer used for forming 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, an insulating layer having excellent insulation reliability is realized even when a thin resin composition layer is used in combination with an inner circuit board having a region with a low circuit conductor occupation ratio. can do.

  In the present invention, even if the thickness of the insulating layer formed on the inner circuit board on the circuit conductor is as thin as 15 μm or less, excellent insulation reliability can be realized. In the present invention, the thickness on the circuit conductor of the insulating layer formed on the inner circuit board is 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, or 10 μm or less without a problem of deterioration of insulation reliability. It can be thinned and contributes significantly to thinning of the multilayer printed wiring board. The lower limit of the thickness of the insulating layer formed on the inner circuit board on the circuit conductor is not particularly limited, but is preferably 1 μm or more from the viewpoint of obtaining sufficient insulation reliability.

  In a preferred embodiment, the insulating layer is formed by thermosetting the resin composition layer.

Inorganic filling in the resin composition constituting the resin composition layer from the viewpoint of sufficiently reducing the thermal expansion coefficient of the insulating layer and suppressing delamination and circuit distortion due to the difference in thermal expansion between the insulating layer and the conductor layer The content of the material is preferably 50% by mass or more, more preferably 55% by mass or more, and further preferably 60% by mass or more.
In addition, in this invention, content of each component which comprises a resin composition is a value when the non-volatile component in a resin composition is 100 mass%.

  As described above, when a resin composition having a high inorganic filler content is used, the influence of the swelling step in step (I) and the roughening step in step (II) on the insulation reliability of the resulting insulating layer becomes significant. Insulation reliability is likely to decrease. On the other hand, in the method for producing a multilayer printed wiring board of the present invention in which the step (I) and the step (II) are performed under specific conditions, an inorganic filler is contained without reducing the insulation reliability of the insulating layer. Higher amounts of the resin composition can be used. For example, the content of the inorganic filler in the resin composition may be increased to 62% by mass or more, 64% by mass or more, 66% by mass or more, 68% by mass or more, 70% by mass or more, or 72% by mass or more. .

  The upper limit of the content of the inorganic filler in the resin composition is preferably 90% by mass or less, more preferably 85% by mass or less, from the viewpoint of preventing a decrease in mechanical strength of the insulating layer.

  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 “SOC2” and “SOC1” manufactured by Admatechs.

  The average particle diameter of the inorganic filler is preferably in the range of 0.01 μm to 2 μm, preferably 0.05 μm to 1.5 μm, from the viewpoint of embedding of the circuit conductor when the resin composition layer is laminated on the inner circuit board. The range is more preferable, the range of 0.07 μm to 1 μm is still more preferable, and the range of 0.1 μm to 0.8 μm is still more preferable. 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-500 manufactured by Horiba, Ltd. can be used.

  Inorganic filler is one kind of aminosilane coupling agent, epoxysilane 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. Examples of commercially available surface treatment agents include “KBM403” (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and “KBM803” (3-mercaptopropyltrimethoxy manufactured by Shin-Etsu Chemical Co., Ltd.). Silane), Shin-Etsu Chemical Co., Ltd. “KBE903” (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd. “KBM573” (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd. "SZ-31" (Hexamethyldisilazane) manufactured by Co., Ltd.

The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. Carbon content per unit surface area of the inorganic filler, from the viewpoint of improving dispersibility of the inorganic filler is preferably 0.02 mg / ^{m 2} or more, 0.1 mg / ^{m 2} or more preferably, 0.2 mg / ^{m 2} The above is more preferable. On the other hand, 1 mg / m ² or less is preferable, 0.8 mg / m ² or less is more preferable, and 0.5 mg / m ² or less is more preferable from the viewpoint of preventing an increase in the melt viscosity of the resin varnish or the sheet form. preferable.

  The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler surface-treated with the surface treatment agent and ultrasonically cleaned at 25 ° C. for 5 minutes. After removing the supernatant and drying the solid, the carbon amount per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, “EMIA-320V” manufactured by HORIBA, Ltd. can be used.

In one embodiment, the resin composition constituting the resin composition layer includes a thermosetting resin in addition to the inorganic filler. As a thermosetting resin, the conventionally well-known thermosetting resin used when forming the insulating layer of a multilayer printed wiring board can be used, An epoxy resin is especially preferable. The resin composition constituting the resin composition layer may also contain a curing agent. Accordingly, in one embodiment, the resin composition includes an epoxy resin and a curing agent in addition to the inorganic filler. The resin composition constituting the resin composition layer may further contain additives such as a thermoplastic resin, a curing accelerator, a flame retardant, and rubber particles as necessary.
Hereinafter, an epoxy resin, a curing agent, and an additive that can be used as a material for the resin composition will be described.

-Epoxy resin-
Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol epoxy resin, naphthol novolac epoxy resin, phenol novolac. Type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin , Linear aliphatic epoxy resin, epoxy resin having butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy Resins, cyclohexanedimethanol type epoxy resins, naphthylene ether type epoxy resins and trimethylol type epoxy resins. An epoxy resin may be used individually by 1 type, or may use 2 or more types together.

  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 or more is preferably an epoxy resin having two or more epoxy groups in one molecule. Among them, it has two or more epoxy groups in one molecule and has a liquid epoxy resin (hereinafter referred to as “liquid epoxy resin”) at a temperature of 20 ° C. and three or more epoxy groups in one molecule. And a solid epoxy resin at a temperature of 20 ° C. (hereinafter referred to as “solid epoxy resin”). By using a liquid epoxy resin and a solid epoxy resin in combination as an epoxy resin, a resin composition having excellent flexibility can be obtained. Moreover, the breaking strength of the cured body (insulating layer) formed by thermosetting the resin composition is also improved.

  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.

  Examples of the liquid epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, and naphthalene type epoxy resin. Specific examples of the liquid epoxy resin include “HP4032”, “HP4032D”, “EXA4032SS”, “HP4032SS” (naphthalene type epoxy resin) manufactured by DIC Corporation, and “jER828EL” (bisphenol A) manufactured by Mitsubishi Chemical Corporation. Type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin), "ZX1059" (bisphenol A type epoxy resin and bisphenol F type epoxy) manufactured by Nippon Steel Chemical Co., Ltd. Resin mixture). These may be used individually by 1 type, or may use 2 or more types together.

  Examples of solid epoxy resins include tetrafunctional naphthalene type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol epoxy resins, naphthol novolac epoxy resins, biphenyl type epoxy resins, and naphthylene ether type epoxy resins. Can be mentioned. Specific examples of the solid epoxy resin include “HP-4700”, “HP-4710” (tetrafunctional naphthalene type epoxy resin), “N-690” (cresol novolac type epoxy resin) manufactured by DIC Corporation, “ N-695 ”(cresol novolac type epoxy resin),“ HP-7200 ”(dicyclopentadiene type epoxy resin),“ EXA7311 ”,“ EXA7311-G3 ”,“ HP6000 ”(naphthylene ether type epoxy resin), Nippon Kayaku “EPPN-502H” (trisphenol epoxy resin), “NC7000L” (naphthol novolac epoxy resin), “NC3000H”, “NC3000”, “NC3000L”, “NC3100” (biphenyl type epoxy resin), manufactured by Yakuhin Co., Ltd. “ESN475” manufactured by Nippon Steel Chemical Co., Ltd. Tall novolak epoxy resin), "ESN485" (naphthol novolak type epoxy resin), "YX4000H" manufactured by Mitsubishi Chemical Corporation, "YX4000HK", "YL6121" (biphenyl type epoxy resin) and the like.

  When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the quantitative ratio thereof (liquid epoxy resin: solid epoxy resin) is in the range of 1: 0.1 to 1: 5 by mass ratio. preferable. By setting the quantity ratio of the liquid epoxy resin to the solid epoxy resin within such a range, i) moderate adhesiveness is obtained when used in the form of a resin sheet described later, and ii) used in the form of a resin sheet. In this case, sufficient flexibility can be obtained, handling properties can be improved, and iii) an insulating layer having sufficient breaking strength can be obtained. From the viewpoint of the effects i) to iii) above, the quantitative ratio of liquid epoxy resin to solid epoxy resin (liquid epoxy resin: solid epoxy resin) is in the range of 1: 0.5 to 1: 5 by mass ratio. Is more preferable, the range of 1: 1 to 1: 4.5 is more preferable, and the range of 1: 1.5 to 1: 4.5 is particularly preferable. As described above, when an epoxy resin having a high content ratio of the liquid epoxy resin is used, the mass reduction amount (M2) per unit area of the insulating layer in the step (II) tends to increase.

  The content of the epoxy resin in the resin composition is preferably 3% by mass to 50% by mass, more preferably 5% by mass to 45% by mass, still more preferably 5% by mass to 40% by mass, and 7% by mass to 35% by mass. % Is particularly preferred.

-Curing agent-
The curing agent is not particularly limited as long as it has a function of curing the epoxy resin. For example, a phenolic curing agent, a naphthol curing agent, an active ester curing agent, a benzoxazine curing agent, and a cyanate ester curing agent may be used. Can be mentioned. A hardening | curing agent may be used individually by 1 type, or may use 2 or more types together.

  As the phenol-based curing agent and the naphthol-based curing agent, a phenol-based curing agent having a novolak structure or a naphthol-based curing agent having a novolak structure is preferable from the viewpoint of heat resistance and water resistance. Further, from the viewpoint of adhesion strength (peel strength) with the conductor layer, a nitrogen-containing phenol-based curing agent is preferable, and a triazine skeleton-containing phenol-based curing agent is more preferable. Among these, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion strength (peel strength) with the conductor layer, it is preferable to use a triazine skeleton-containing phenol novolac resin as a curing agent.

  Specific examples of the phenol-based curing agent and the naphthol-based curing agent include, for example, “MEH-7700”, “MEH-7810”, “MEH-7785” manufactured by Meiwa Kasei Co., Ltd., and Nippon Kayaku Co., Ltd. “NHN”, “CBN”, “GPH”, “SN170”, “SN180”, “SN190”, “SN475”, “SN485”, “SN495”, “SN375”, “SN395” manufactured by Toto Kasei Co., Ltd. And “LA7052”, “LA7054”, “LA3018” manufactured by DIC Corporation, “GDP-6140” manufactured by Gunei Chemical Industry Co., Ltd., and the like.

  From the viewpoint of adhesion strength (peel strength) with the conductor layer, an active ester curing agent is also preferable. 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, dicyclopentadienyl diphenol, phenol novolac and the like.

  The active ester curing agent includes an active ester compound containing a dicyclopentadienyl diphenol structure, an active ester compound containing a naphthalene structure, an active ester compound containing a phenol novolac acetylated product, and an active ester containing a phenol novolak benzoylated product. Compounds are preferred, and active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadienyl diphenol structure are more preferred.

  Commercially available active ester curing agents include "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T" (DIC Corporation) as active ester compounds containing a dicyclopentadienyl diphenol structure. Manufactured product), "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing a naphthalene structure, "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated product of phenol novolac, Examples of the active ester compound containing a benzoylated compound include “YLH1026” (manufactured by Mitsubishi Chemical Corporation).

  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.

  Examples of cyanate ester-based curing agents include bisphenol A dicyanate, polyphenol cyanate (oligo (3-methylene-1,5-phenylene cyanate), 4,4′-methylenebis (2,6-dimethylphenyl cyanate), 4,4. '-Ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis (4-cyanate) phenylpropane, 1,1-bis (4-cyanatephenylmethane), bis (4-cyanate-3,5-dimethyl) Bifunctional cyanate resins such as phenyl) methane, 1,3-bis (4-cyanatephenyl-1- (methylethylidene)) benzene, bis (4-cyanatephenyl) thioether, and bis (4-cyanatephenyl) ether, phenol Novolac and K Examples include polyfunctional cyanate resins derived from sol novolac, prepolymers in which these cyanate resins are partly triazines, etc. Specific examples of cyanate ester curing agents include “PT30” manufactured by Lonza Japan Co., Ltd. “PT60” (both phenol novolac-type polyfunctional cyanate ester resins), “BA230” (prepolymer in which a part or all of bisphenol A dicyanate is triazine-modified), and the like.

  The amount ratio of the epoxy resin and the curing agent is preferably a ratio of [total number of epoxy groups of the epoxy resin]: [total number of reactive groups of the curing agent] in the range of 1: 0.2 to 1: 2. 1: 0.3-1: 1.5 are more preferable, and 1: 0.4-1: 1 are still more preferable. Here, the reactive group of the curing agent is an active hydroxyl group, an active ester group or the like, and varies depending on the type of the curing agent. Moreover, the total number of epoxy groups of the epoxy resin is a value obtained by dividing the value obtained by dividing the solid mass of each epoxy resin by the epoxy equivalent for all epoxy resins, and the total number of reactive groups of the curing agent is: The value obtained by dividing the solid mass of each curing agent by the reactive group equivalent is the total value for all curing agents.

  As described above, when a phenolic curing agent is used as the curing agent, the mass reduction amount (M2) per unit area of the insulating layer in the step (II) tends to increase, and when an active ester curing agent is used, M2 decreases. There is a tendency. The cyanate ester-based curing agent exhibits intermediate characteristics between the phenol-based curing agent and the active ester-based curing agent in terms of the effect on the mass reduction amount (M2) per unit area of the insulating layer in the step (II).

  In one embodiment, the resin composition used for forming the insulating layer in the method for producing a multilayer printed wiring board of the present invention includes the above-described inorganic filler, epoxy resin, and curing agent. The resin composition includes silica as an inorganic filler and a mixture of a liquid epoxy resin and a solid epoxy resin as an epoxy resin (the mass ratio of liquid epoxy resin: solid epoxy resin is in the range of 1: 0.1 to 1: 5. Is preferable, a range of 1: 0.5 to 1: 4.5 is more preferable, a range of 1: 1 to 1: 4.5 is further preferable, and a range of 1: 1.5 to 1: 4.5 is particularly preferable. It is preferable that each of the curing agent includes one or more selected from the group consisting of a phenolic curing agent, a naphthol curing agent, an active ester curing agent, and a cyanate ester curing agent. Regarding the resin composition layer containing a combination of such specific components, the preferred content of the inorganic filler, the epoxy resin, and the curing agent is as described above, and among them, the content of the inorganic filler is 50 mass. It is preferable that the content of the epoxy resin is 3% by mass to 50% by mass, the content of the inorganic filler is 50% by mass to 90% by mass, and the content of the epoxy resin is 5% by mass to 45% by mass. It is more preferable that Regarding the content of the curing agent, the ratio of the total number of epoxy groups of the epoxy resin to the total number of reactive groups of the curing agent is preferably in the range of 1: 0.2 to 1: 2, more preferably 1: It is preferable to make it contain in the range of 0.3-1: 1.5, More preferably, it is the range of 1: 0.4-1: 1.

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

-Thermoplastic resin-
Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyimide resin, polyamideimide resin, polyethersulfone resin, and polysulfone resin. Among these, phenoxy resin and polyvinyl acetal resin are preferable, and phenoxy resin is more preferable. preferable. A thermoplastic resin may be used individually by 1 type, or may use 2 or more types together.

  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, and still more preferably in the range of 20,000 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, or may use 2 or more types together. 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.

  As the polyvinyl acetal resin, polyvinyl butyral resin is preferable, and specific examples thereof include electrified butyral 4000-2, 5000-A, 6000-C, 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd., Sekisui Chemical Co., Ltd. Examples include S-LEC BH series, BX series, KS series, BL series, and BM series.

  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.

  Content of the thermoplastic resin in a resin composition is not specifically limited, For example, it is good as it is the range of 0.1 mass%-20 mass%. As described above, when the content of the thermoplastic resin in the resin composition increases, the mass reduction amount (M2) per unit area of the insulating layer in the step (II) tends to increase.

-Curing accelerator-
Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and guanidine-based curing accelerators. Of these, amine-based curing accelerators and imidazole-based curing accelerators are preferable.

  Examples of phosphorus curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl) triphenylphosphonium thiocyanate. , Tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, and the like.

  Examples of amine curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6, -tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo. (5,4,0) -undecene and the like are mentioned, and 4-dimethylaminopyridine and 1,8-diazabicyclo (5,4,0) -undecene are preferable.

  Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl- 2 Phenylimidazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino- 6- [2′-Methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl- 4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 1-dodecyl-2-methyl Examples include imidazole compounds such as 3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins, such as 2-ethyl-4-methylimidazole and 1-benzyl-2-phenyl. Imidazole is preferred.

  Examples of the guanidine curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1- (o-tolyl) guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, Tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo [4.4.0] dec-5-ene, 7-methyl-1,5,7-triazabicyclo [4.4.0] Deca-5-ene, 1-methyl biguanide, 1-ethyl biguanide, 1-n-butyl biguanide, 1-n-octadecyl biguanide, 1,1-dimethyl biguanide, 1,1-diethyl biguanide, 1-cyclohexyl biguanide, 1 -Allyl biguanide, 1-phenyl biguanide, 1- ( - tolyl) biguanide, and the like.

  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 used in the range of 0.01% by mass to 3% by mass when the total amount of the nonvolatile components of the epoxy resin and the curing agent is 100% by mass.

-Flame retardant-
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. 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 layer is not particularly limited, but is preferably 0.5% by mass to 10% by mass, more preferably 1% by mass to 9% by mass, and 1.5% by mass to 8% by mass. Further preferred.

-Rubber particles-
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). A rubber particle may be used individually by 1 type, or may use 2 or more types together.

  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. As described above, when the content of the rubber particles in the resin composition is increased, the mass reduction amount (M2) per unit area of the insulating layer in the step (II) tends to increase.

  The resin composition constituting the resin composition layer may contain other additives as necessary. Examples of such other additives include organic copper compounds, organic zinc compounds, and organic cobalt compounds. And resin additives such as organic fillers, thickeners, antifoaming agents, leveling agents, adhesion-imparting agents, and coloring agents.

<Other processes>
The method for producing a multilayer printed wiring board of the present invention may include other steps as long as the steps (I) and (II) are carried out under the specific conditions. Hereinafter, a suitable example is shown about such other processes.

In a preferred embodiment, the method for producing a multilayer printed wiring board of the present invention includes the following steps (A), (B) and (C) before step (I).
(A) A step of laminating a resin sheet including a support film and a resin composition layer provided on the support film to an inner circuit board so that the resin composition layer is bonded to the inner circuit board. (B) Resin Step of forming the insulating layer by thermosetting the composition layer (C) Step of forming a via hole by drilling the insulating layer

-Process (A)-
In the step (A), a resin sheet including a support film and a resin composition layer provided on the support film is laminated to the inner circuit board so that the resin composition layer is bonded to the inner circuit board.

  The resin composition constituting the resin composition layer is as described above. The thickness of the resin composition layer is preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably from the viewpoint of reducing the thickness of the insulating layer to reduce the thickness of the multilayer printed wiring board. It is 25 μm or less or 20 μm or less. Although the minimum of the thickness of a resin composition layer is not specifically limited, From a viewpoint of the insulation reliability of the insulating layer obtained, it is 3 micrometers or more normally.

  A film made of a plastic material is preferably used as the support film. 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 “PET”). PC ”), 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.

  The support film may be subjected to mat treatment or corona treatment on the surface to be bonded to the resin composition layer. Moreover, as a support film, you may use the support film with a release layer which has a release layer in the surface of the side joined to a resin composition layer.

  Although the thickness of a support film is not specifically limited, The range of 5 micrometers-75 micrometers is preferable, and the range of 10 micrometers-60 micrometers is more preferable. In addition, when a support film is a support body with a release layer, it is preferable that the thickness of the whole support film with a release layer is the said range.

  The resin sheet is prepared by, for example, preparing a resin varnish in which a resin composition is dissolved in an organic solvent, and applying the resin varnish on a support film using a die coater or the like, and further heating or blowing hot air to the organic solvent. It can manufacture by drying and forming a resin composition layer.

  Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone (hereinafter also referred to as “MEK”) and cyclohexanone, acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate, Examples thereof include carbitols such as cellosolve and 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, or may use 2 or more types together.

  The drying conditions are not particularly limited, but the drying is performed so that the content of the organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the organic solvent in the resin varnish, for example, when using a resin varnish containing 30% by mass to 60% by mass of the organic solvent, the resin composition is dried at 50 ° C. to 150 ° C. for 3 to 10 minutes. A layer can be formed.

  In the resin sheet, a protective film according to the support film can be further laminated on the surface of the resin composition layer that is not bonded to the support film (that is, the surface opposite to the support film). Although the thickness of a protective film is not specifically limited, For example, they are 1 micrometer-40 micrometers. By laminating the protective film, it is possible to prevent dust and the like from being attached to the surface of the resin composition layer and scratches. The resin sheet can be wound and stored in a roll shape, and can be used by peeling off the protective film when manufacturing a multilayer printed wiring board.

The conditions for the laminating treatment are not particularly limited, and known conditions used for forming an insulating layer of a multilayer printed wiring board using a resin sheet can be employed. For example, it can be performed by pressing a heated metal plate such as a SUS mirror plate from the support side of the resin sheet. In this case, it is preferable not to press the metal plate directly, but to press through an elastic material such as heat-resistant rubber so that the resin sheet sufficiently follows the circuit irregularities of the inner circuit board. The pressing temperature is preferably in the range of 70 ° C. to 140 ° C., the pressing pressure is preferably in the range of 1 kgf / cm ^{2 to} 11 kgf / cm ² (0.098 MPa to 1.079 MPa), and the pressing time is preferably The range is from 5 seconds to 3 minutes. The laminating process is preferably performed under a reduced pressure of 20 mmHg (26.7 hPa) or less. Lamination treatment can be performed using 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.

  After the laminating process, the resin sheet laminated on the inner layer circuit board may be heated and pressurized to perform the smoothing process.

  The smoothing treatment is generally carried out by heating and pressurizing the resin sheet with a heated metal plate or metal roll under normal pressure (atmospheric pressure). The heating and pressurizing conditions can be the same conditions as the laminating conditions.

  The laminating process and the smoothing process may be continuously performed using a vacuum laminator.

  In addition, a support film is peeled after a process (A). You may implement a support film between a process (A) and a process (B), between a process (B) and a process (C), or between a process (C) and a process (I). The support may be peeled off manually or mechanically by an automatic peeling device.

-Process (B)-
In the step (B), the resin composition layer 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, although the thermosetting conditions of the resin composition layer vary depending on the composition of the resin composition used for the resin composition layer, 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, it is 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).

  Before thermosetting, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermosetting, the resin composition layer is placed 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 minutes, more preferably 15 minutes to 120 minutes). The thermosetting of the resin composition layer is preferably performed under atmospheric pressure (normal pressure).

-Step (C)-
In step (C), a via hole is formed by drilling 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 support film exists, a via hole can be formed in the insulating layer by irradiating a laser beam on the support film. The size of the opening of the via hole is selected according to the fineness of the component to be mounted, but the top diameter is preferably in the range of 40 μm to 500 μm.

  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.

  When forming a via hole, a resin residue (smear) derived from an insulating layer may be deposited on the bottom of the via. Such a smear can be removed by carrying out step (I) and step (II).

In a preferred embodiment, the method for producing a multilayer printed wiring board of the present invention includes the following steps (D) and (E) after step (II).
(D) Step of neutralizing the surface of the insulating layer with a neutralizing solution (E) Step of forming a conductor layer by plating on the surface of the insulating layer

-Process (D)-
In the step (D), the surface of the insulating layer is neutralized with a neutralizing solution.

  The neutralization treatment may be performed by any conventionally known procedure in the production of multilayer printed wiring boards. In a preferred embodiment, the neutralization treatment is performed by immersing the insulating layer surface in a neutralizing solution at 30 to 50 ° C. (preferably 35 to 45 ° C.) for 3 to 10 minutes (preferably 3 to 8 minutes). To implement. The neutralizing solution is preferably an acidic aqueous solution, and commercially available products include “Circuposit MLB216-5” manufactured by Rohm & Haas Electronic Materials Co., Ltd., and “Reduction Solutionin Securigant P” manufactured by Atotech Japan Co., Ltd. Is mentioned.

-Process (E)-
In the step (E), a conductor layer is formed on the surface of the insulating layer by plating.

  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 on the surface of the insulating layer by plating using various conventionally known methods such as a full additive method and a semi-additive method.

  When forming a conductor layer by a semi-additive method, you may form in the following procedures. 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.

  The insulating layer and the conductor layer are required to exhibit sufficient adhesion strength (peel strength), and in general, such adhesion is obtained by an anchor effect caused by unevenness on the surface of the insulating layer. However, if the unevenness on the surface of the insulating layer is large, when removing an unnecessary plating seed layer by etching when forming a wiring pattern, it is difficult to remove the seed layer in the uneven portion, and the plating seed layer in the uneven portion is sufficiently removed. When etching was performed under the conditions to obtain, the dissolution of the wiring pattern became prominent and hindered the fine wiring. On the other hand, in the method for producing a multilayer printed wiring board of the present invention in which the step (I) and the step (II) are performed under specific conditions, sufficient adhesion strength between the insulating layer and the conductor layer is maintained. An insulating layer having a surface with low roughness can be advantageously obtained (the roughness of the surface of the insulating layer is as described above). Combined with the effect of realizing excellent insulation reliability even when the thickness of the insulating layer is reduced, the method for manufacturing a multilayer printed wiring board according to the present invention makes the multilayer printed wiring board thinner and finer. It contributes remarkably to both.

The multilayer printed wiring board produced by the method of the present invention has sufficient adhesion strength (peel strength) to the surface of the insulating layer, that is, preferably 0.4 kgf, although the surface roughness of the insulating layer is low as described above. / Cm or more, more preferably 0.45 kgf / cm or more, still more preferably 0.5 kgf / cm or more, even more preferably 0.51 kgf / cm or more, 0.52 kgf / cm or more, or 0.53 kgf / cm or more, The conductor layer which exhibits is provided. Higher adhesion strength is preferable, but generally 1.5 kgf / cm is the upper limit.
In the present invention, the adhesion strength between the insulating layer and the conductor layer refers to a peel strength (90-degree peel strength) when the conductor layer is peeled in a direction perpendicular to the insulating layer (90-degree direction). The peel strength when the layer is peeled in the direction perpendicular to the insulating layer (90-degree direction) can be determined by measuring with a tensile tester. Examples of the tensile tester include “AC-50C-SL” manufactured by TSE Corporation.

  Even when the insulating layer is formed by using a resin composition having a high inorganic filler content, combined with the effect of realizing good insulation reliability, the method for producing a multilayer printed wiring board of the present invention Therefore, it is possible to realize a multilayer printed wiring board that is remarkably excellent in reflow resistance.

  As mentioned above, although it illustrated about the other process which the manufacturing method of the multilayer printed wiring board of this invention may include, as long as implementing process (I) and process (II) on specific conditions, the method of this invention is other than the above A process may be included.

  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) Base treatment of inner layer circuit board As an inner layer circuit board, a circuit conductor (with a 1 mm square lattice wiring pattern (having a region with a remaining copper ratio of 60% and a region with a remaining copper ratio of 90%) ( A glass cloth base epoxy resin double-sided copper-clad laminate [copper foil thickness: 18 μm, substrate thickness: 0.3 mm, “R1515F” manufactured by Panasonic, Inc.] having copper) on both sides was prepared. Both surfaces of the inner layer circuit board were immersed in “CZ8100” manufactured by MEC Co., Ltd., and the copper surface was roughened (copper etching amount 1 μm).
(2) Lamination of resin sheet Using the batch type vacuum press laminator (manufactured by Nichigo Morton Co., Ltd., 2-stage buildup laminator CVP700), the resin composition layer is an inner circuit board. Was laminated on both sides of the inner circuit board so as to be in contact with each other. Lamination was carried out by reducing the pressure for 30 seconds to a pressure of 13 hPa or less and then pressing the film at 100 ° C. and a pressure of 0.74 MPa for 30 seconds. Next, hot pressing was performed at 100 ° C. and a pressure of 0.5 MPa for 60 seconds.
(3) Thermosetting of resin composition layer The inner layer circuit board on which the resin sheet was laminated was heated at 180 ° C. for 30 minutes, and the resin composition layer was thermoset to form an insulating layer.
(4) Swelling and roughening of insulating layer After forming a via hole, the surface of the insulating layer was swollen and roughened. In the swelling process, the surface of the insulating layer is swelled ("Circuposit MLB211" manufactured by Rohm and Haas Electronic Materials Co., Ltd.) so that the amount of mass increase (M1) per unit area of the insulating layer becomes the value shown in Table 1 below. And a mixed swelling solution containing “Cuposit Z”, Circuposit MLB211: 20%, Cuposit Z: 10%) was immersed at 60 ° C. or 80 ° C. for 5 to 20 minutes. In the roughening step, the surface of the insulating layer is oxidized with an oxidizing agent (Circuposit MLB213A manufactured by Rohm and Haas Electronic Materials Co., Ltd.) so that the amount of mass decrease (M2) per unit area of the insulating layer becomes the value shown in Table 1 below. -1 ”and“ Circuposit MLB213B-1 ”, a mixed oxidant solution, Circupit MLB213A-1: 12%, Circupposit MLB213B-1: 15%) was immersed in the mixture at 80 ° C. for 5 to 20 minutes. After the swelling and roughening process, it was washed with water. This roughened the surface of the insulating layer.
(5) Neutralization Treatment of Insulating Layer Next, the surface of the insulating layer was immersed in a neutralizing solution (“Circuposit MLB216-5” manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 45 ° C. for 5 minutes, and then 130 ° C. For 15 minutes.
(6) Formation of conductor layer by plating According to a semi-additive method, a conductor layer was formed by plating on the surface of the insulating layer. Specifically, a copper layer having a thickness of 1 μm was first formed by electroless copper plating using Atotech Japan Co., Ltd. pharmaceutical solution. Thereafter, electrolytic copper plating was performed to form a conductor layer (copper layer) having a total thickness of 15 μm.
The thickness of the insulating layer on the circuit conductor in the region where the remaining copper ratio was 90% was about 16 μm, and the thickness of the insulating layer on the circuit conductor in the region where the remaining copper ratio was 60% was about 10 μm.

<Measurement of mass increase (M1) per unit area of insulating layer in swelling process>
The substrate obtained in the above (3) was cut into 10 cm square, and the support film was peeled off. Next, the substrate was dried at 130 ° C. for 15 minutes, and the substrate mass X1 (mg) immediately after drying was measured. Then, the board | substrate was attached | subjected to the swelling process and the water washing process was performed. Next, after removing water droplets on the substrate surface with an air knife, the substrate mass X2 (mg) was measured.
The amount of mass increase (M1) per unit area of the insulating layer in the swelling process was determined by substituting the measured values of X1 and X2 into the following formula (1). In the following formula (1), A represents the surface area of the insulating layer and is 100 cm ² .
M1 (mg / cm ² ) = (X2−X1) / A (1)

<Measurement of mass reduction (M2) per unit area of insulating layer in roughening process>
The mass reduction amount (M2) per unit area of the insulating layer in the roughening step was determined by the following formula (2). In formula (2), X1 and A represent the same meaning as described above, and X3 represents the substrate mass (mg) after the roughening step. X3 is the substrate mass immediately after the substrate after the roughening step is washed with water and dried at 130 ° C. for 15 minutes.
M2 (mg / cm < ² >) = (X1-X3) / A (2)

<Method for evaluating insulation reliability of insulating layer>
A circular conductor pattern having a diameter of 10 cm was formed on the conductor layer side of the evaluation substrate obtained in (6) above. Then, using a highly accelerated life test apparatus ("PM422" manufactured by ETAC) with the circular conductor side as the + electrode and the circuit conductor (copper) side of the inner layer circuit board as the-electrode, 130 ° C, 85% relative humidity, 3% The insulation resistance value was measured with an electrochemical migration tester (“ECM-100” manufactured by J-RAS Co., Ltd.) (n = 5) when 200 hours passed under the condition of applying a 3 V DC voltage. In all five tests, the case where the resistance value was 10 ⁷ Ω or more was evaluated as “◯”, and the case where the resistance value was less than 10 ⁷ Ω was evaluated as “X”.

<Measurement of adhesion strength (peel strength) of conductor layer>
The conductor layer of the evaluation board obtained in (6) above was cut into a 10 mm wide and 100 mm long part, and one end was peeled off to grasp the grip (Autocom type tester “AC- 50C-SL "), and using an Instron universal testing machine, measure the load (kgf / cm) when peeling 35 mm vertically at a speed of 50 mm / min at room temperature, and peel strength Asked.

<Reflow resistance test>
Appearance change when the evaluation substrate obtained in the above (6) is cut to a size of 3 cm × 12 cm and repeatedly passed 10 times through a reflow apparatus (“HAS-6116” manufactured by Nippon Antom Co., Ltd.) having a peak temperature of 260 ° C. Was observed (n = 5). In all five tests, the case where there was no peeling of the conductor layer (copper layer) or insulating layer (blister) was indicated as “◯”, and the case where there was a blister even once was indicated as “x”.

  Resin sheets 1, 2, and 3 used in Examples and Comparative Examples were prepared by the following procedure.

<Production Example 1 (Production of Resin Sheet 1)>
12 parts of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent of about 185), 3 parts of naphthalene type epoxy resin (DIC Corporation "HP4032SS", epoxy equivalent of about 144), biphenyl type epoxy resin (Mitsubishi Chemical Corporation "YX4000HK", epoxy equivalent of about 185) 6 parts, biphenyl type epoxy resin (Nippon Kayaku "NC3000H", epoxy equivalent of about 288) 25 parts, phenoxy resin (Mitsubishi Chemical Corporation ) “YX6954BH30”, MEK / cyclohexanone = 1/1 solution having a solid content of 30% by mass) was dissolved in 15 parts of solvent naphtha with stirring. After cooling to room temperature, 20 parts of a triazine skeleton-containing phenol novolac curing agent (“LA-7054” manufactured by DIC Corporation, MEK solution having a hydroxyl equivalent of 125 and a solid content of 60%), a naphthol curing agent ( “SN-485” manufactured by Nippon Steel Chemical Co., Ltd., 10 parts of hydroxyl equivalent 215, 60% solid content MEK solution, curing accelerator (4-dimethylaminopyridine (DMAP), 5% solid content MEK solution) ) 0.5 parts, flame retardant (“HCA-HQ” manufactured by Sanko Co., Ltd., 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide 3 parts of average particle size 2), spherical silica (average particle size 0.5 μm, manufactured by Admatechs Co., Ltd.) “SOC2” surface-treated with an aminosilane coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.) , Unit surface area 80 parts of carbon per 0.39 mg / m ² ) were mixed and dispersed uniformly with a high-speed rotary mixer to prepare resin varnish 1.
Next, on the release layer side of the PET film with an alkyd resin release layer (“AL5” manufactured by Lintec Co., Ltd., thickness: 38 μm), the resin varnish is dried so that the thickness of the resin composition layer after drying is 18 μm. 1 was applied uniformly and dried at 80 to 120 ° C. (average 100 ° C.) for 3 minutes to prepare a resin sheet 1.

<Production Example 2 (Production of Resin Sheet 2)>
Bisphenol type epoxy resin (“ZX1059” manufactured by Nippon Steel Chemical Co., Ltd., 1: 1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent of about 169), 5 parts, biphenyl type epoxy resin (manufactured by Mitsubishi Chemical Corporation) "YX4000HK", epoxy equivalent of about 185) 12 parts, dicyclopentadiene type epoxy resin (DIC Corporation "HP7200H", epoxy equivalent of about 275) 9 parts, phenoxy resin (Mitsubishi Chemical Corporation "YL7553BH30", solid 16 parts of MEK / cyclohexanone (1/1 solution of 30% by mass) were dissolved in 30 parts of solvent naphtha with stirring. After cooling to room temperature, 40 parts of an active ester curing agent (“HPC8000-65T” manufactured by DIC Corporation, a toluene solution having an active group equivalent of about 223 and a nonvolatile content of 65% by mass), a curing accelerator (4 -3 parts of dimethylaminopyridine, 5 mass% solid MEK solution), spherical silica (average particle size of 0.5 μm, surface treated with an aminosilane coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.), “SOC2” manufactured by Admatechs Co., Ltd., 150 parts of carbon per unit surface area 0.39 mg / m ² ) were mixed and uniformly dispersed with a high-speed rotating mixer to prepare resin varnish 2.
Subsequently, the resin sheet 2 was produced in the same procedure as in Production Example 1 using the resin varnish 2.

<Production Example 3 (Production of Resin Sheet 3)>
3 parts of bisphenol type epoxy resin (“ZX1059” manufactured by Nippon Steel Chemical Co., Ltd., 1: 1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent of about 169), naphthalene type epoxy resin (manufactured by DIC Corporation “ "HP4032SS", epoxy equivalent of 144) 3 parts, biphenyl type resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 185) 6 parts, dicyclopentadiene type epoxy resin (DIC Corporation "HP7200H", epoxy) 20 parts by weight (equivalent of about 275) and 8 parts of phenoxy resin ("YL7553BH30" manufactured by Mitsubishi Chemical Corporation, MEK solution with a solid content of 30% by mass) were dissolved in 20 parts of solvent naphtha with stirring. After cooling to room temperature, 20 parts of a prepolymer of bisphenol A dicyanate (“BA230S75” manufactured by Lonza Japan Co., Ltd., MEK solution having a cyanate equivalent of about 232 and a nonvolatile content of 75% by mass), a phenol novolac type polyfunctional cyanate Ester resin (Lonza Japan Co., Ltd. “PT30S”, cyanate equivalent of about 133, MEK solution with non-volatile content of 85% by mass), active ester hardener (DIC Corporation “HPC8000-65T”, active group equivalent About 223 non-volatile content 65% by mass toluene solution) 8 parts, curing accelerator (4-dimethylaminopyridine, solid content 5% by mass MEK solution) 0.3 parts, curing accelerator (manufactured by Tokyo Chemical Industry Co., Ltd.) 4 parts of cobalt (III) acetylacetonate, MEK solution having a solid content of 1% by mass, flame retardant (“HCA-” manufactured by Sanko Co., Ltd.) Q ”, 3 parts of 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 2 μm), aminosilane coupling agent (Shin-Etsu Chemical) 100 parts of spherical silica (average particle size 0.5 μm, “SOC2” manufactured by Admatechs Co., Ltd., carbon amount 0.39 mg / m ² ) manufactured by Kogyo Co., Ltd., “KBM573”) Were mixed and dispersed uniformly with a high-speed rotary mixer to prepare a resin varnish 3.
Subsequently, the resin sheet 3 was produced in the same procedure as in Production Example 1 using the resin varnish 3.

  The compositions of the resin composition layers of the resin sheets 1 to 3 are collectively shown in Table 1.

<Example 1>
Use resin sheet 1, following the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.12 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.29 mg / cm ^2. Each evaluation result is shown in Table 2.

<Example 2>
Use resin sheet 2, according to the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.10 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.20 mg / cm ^2. Each evaluation result is shown in Table 2.

<Example 3>
Use resin sheet 3, according to the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.09 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.22 mg / cm ^2. Each evaluation result is shown in Table 2.

<Comparative Example 1>
Use resin sheet 1, following the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.26 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.21 mg / cm ^2. Each evaluation result is shown in Table 2.

<Comparative example 2>
Use resin sheet 2, according to the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.22 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.18 mg / cm ^2. Each evaluation result is shown in Table 2.

<Comparative Example 3>
Use resin sheet 1, following the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.31 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.46 mg / cm ^2. Each evaluation result is shown in Table 2.

<Comparative Example 4>
Use resin sheet 3, according to the procedure in [Measurement and evaluation for the substrate preparation], M1 is 0.18 mg / ^cm 2, M2 has produced an evaluation substrate under the conditions of 0.42 mg / cm ^2. Each evaluation result is shown in Table 2.

<Comparative Example 5>
Using the resin sheet 1, an evaluation substrate was produced under the conditions of M1 of 0.31 mg / cm ² and M2 of 0.38 mg / cm ² according to the procedure described in [Preparation of measurement / evaluation substrate]. Each evaluation result is shown in Table 2.

Claims (14)

(I) A method for producing a multilayer printed wiring board , comprising: a step of swelling an insulating layer formed on an inner circuit board with a swelling liquid; and (II) a step of roughening the surface of the insulating layer with an oxidizing agent in this order. ,
The amount of mass increase (M1) per unit area of the insulating layer in step (I) is 0.30 mg / cm ² or less,
A method for producing a multilayer printed wiring board, wherein a mass reduction amount (M2) per unit area of the insulating layer in step (II) is 0.40 mg / cm ² or less, and M1 and M2 satisfy a relationship of M1 ≦ M2.   The method of claim 1, wherein M1 and M2 satisfy a relationship of M1 <M2.   The method according to claim 1, wherein M1 and M2 satisfy a relationship of M1 + 0.05 <M2.   The method as described in any one of Claims 1-3 whose thickness on the circuit conductor of the insulating layer formed on the inner layer circuit board is 15 micrometers or less.   The method as described in any one of Claims 1-3 whose thickness on the circuit conductor of the insulating layer formed on the inner-layer circuit board is 1 micrometer or more and 15 micrometers or less.   The method according to claim 1, wherein the insulating layer is formed by thermosetting the resin composition layer.   The method of Claim 6 that content of the inorganic filler in a resin composition is 50 mass% or more when the non-volatile component in the resin composition which comprises a resin composition layer is 100 mass%.   The content of the inorganic filler in the resin composition is 50% by mass or more and 90% by mass or less when the nonvolatile component in the resin composition constituting the resin composition layer is 100% by mass. the method of.   The method according to claim 7 or 8, wherein the resin composition further comprises an epoxy resin and a curing agent.   The method as described in any one of Claims 1-9 whose arithmetic mean roughness (Ra) of the insulating layer surface is 400 nm or less after process (II).   The method as described in any one of Claims 1-10 whose arithmetic mean roughness (Ra) of the insulating layer surface is 300 nm or less after process (II).   The method according to any one of claims 1 to 11, wherein after step (II), the arithmetic average roughness (Ra) of the surface of the insulating layer is 200 nm or less. The method as described in any one of Claims 1-12 including the following process (A), (B), and (C) before process (I).
(A) A step of laminating a resin sheet including a support film and a resin composition layer provided on the support film to an inner circuit board so that the resin composition layer is bonded to the inner circuit board. (B) Resin Step of forming the insulating layer by thermosetting the composition layer (C) Step of forming a via hole by drilling the insulating layer The method as described in any one of Claims 1-13 including the following process (D) and (E) after process (II).
(D) Step of neutralizing the surface of the insulating layer with a neutralizing solution (E) Step of forming a conductor layer by plating on the surface of the insulating layer