Method for manufacturing wiring board

Abstract

This method for manufacturing a wiring board includes: a step (I) of preparing a laminate including a substrate, an insulating layer, and a thermoplastic film in this order; a step (II) of forming a recess in the thermoplastic film; a step (III) of forming one or both of a via hole and a trench in the insulating layer by plasma processing; and a step (IV) of peeling the thermoplastic film in this order.

Description

Method for manufacturing a wiring board

[0001] The present invention relates to a method for manufacturing a wiring board.

[0002] Wiring boards such as printed wiring boards, package substrates, and interposers generally include an insulating layer and a conductor layer on which wiring can be formed. Via holes or trenches may be formed in the insulating layer of a wiring board (see Patent Document 1). A "via hole" refers to a hole that penetrates the insulating layer. A "trench" refers to a recess that does not penetrate the insulating layer, and is generally formed in a groove shape.

[0003] Japanese Patent Application Laid-Open No. 2022-039763

[0004] Various methods have been proposed for forming via holes or trenches in insulating layers. For example, when an insulating layer is formed from a cured product of a photosensitive resin composition, a method for forming via holes or trenches in the insulating layer by exposure and development using photolithography is available. Furthermore, when an insulating layer is formed from a cured product of a thermosetting resin composition, a method for forming via holes or trenches in the insulating layer by laser irradiation is available. However, the cross-sectional shapes of via holes and trenches formed by these methods are not satisfactory in terms of meeting recent high quality requirements, and further improvement has been required.

[0005] Specifically, the cross-sectional shapes of via holes and trenches are expressed by a taper angle, which is the angle that the side surface of the via hole or trench makes with the plane of the insulating layer. This taper angle is generally required to be close to 90°, but the taper angles of via holes and trenches formed by the conventional method were small.

[0006] Therefore, the present inventors proposed a method for forming via holes or trenches using plasma treatment (Patent Document 1). Specifically, the present inventors proposed a method for forming via holes or trenches by forming a photoresist mask on an insulating layer and then performing plasma treatment on the insulating layer through the mask. Plasma treatment can remove the insulating layer by scraping it in the thickness direction, which is expected to result in a taper angle close to 90°. However, this method required cumbersome labor to form via holes or trenches. Specifically, the method described in Patent Document 1 requires performing a chemical treatment to remove the mask after forming the via holes or trenches. Chemical treatment generally requires time. Furthermore, since cleaning and drying are usually required after the chemical treatment, the number of steps increases. Furthermore, chemical treatment can cause the chemical solution to come into contact with not only the mask but also the insulating layer, which could potentially damage the insulating layer.

[0007] In view of the above circumstances, there has been a demand for the development of a new manufacturing method that can easily manufacture a wiring board having an insulating layer in which via holes or trenches having a good cross-sectional shape are formed.

[0008] The present invention was devised in view of the above-mentioned problems, and aims to provide a new manufacturing method that can easily manufacture a wiring board having an insulating layer in which via holes or trenches having a good cross-sectional shape are formed.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, the present inventors have discovered that a wiring board having an insulating layer in which a via hole or trench having a good cross-sectional shape is formed can be easily produced by a manufacturing method including, in this order: step (I) of preparing a laminate having a substrate, an insulating layer, and a thermoplastic film; step (II) of forming a recess in the thermoplastic film; step (III) of forming one or both of a via hole and a trench in the insulating layer by plasma treatment; and step (IV) of peeling off the thermoplastic film. This finding led to the completion of the present invention. That is, the present invention includes the following.

[0010] [1] A method for manufacturing a wiring board, comprising the steps of: (I) preparing a laminate including, in this order, a substrate, an insulating layer, and a thermoplastic film; (II) forming a recess in the thermoplastic film; (III) forming one or both of a via hole and a trench in the insulating layer by plasma treatment; and (IV) peeling off the thermoplastic film. [2] The method for manufacturing a wiring board according to [1], wherein step (I) comprises: (I-1) forming a resin composition layer including a resin composition on the substrate; and (I-2) curing the resin composition layer. [3] The method for manufacturing a wiring board according to [2], wherein step (I-1) comprises laminating a resin sheet including a thermoplastic film and a resin composition layer and the substrate so that the resin composition layer and the substrate are bonded. [4] The method for manufacturing a wiring board according to any one of [1] to [3], wherein step (II) comprises forming a recess in the thermoplastic film by laser light. [5] The method for manufacturing a wiring board according to any one of [1] to [4], wherein step (II) comprises pressing the thermoplastic film with a mold. [6] The method for manufacturing a wiring board according to any one of [1] to [5], wherein step (II) comprises forming a recess so that the substrate is not exposed at the bottom of the recess. [7] The method for manufacturing a wiring board according to any one of [1] to [6], wherein step (III) comprises irradiating the thermoplastic film with plasma to reduce the thickness of the thermoplastic film and simultaneously removing the insulating layer below the recess to form one or both of a via hole and a trench. [8] The method for manufacturing a wiring board according to any one of [1] to [7], wherein the etching amount of the insulating layer in step (III) is 30% or more relative to 100% of the thickness of the insulating layer in step (I). [9] The method for manufacturing a wiring board according to any one of [1] to [8], wherein step (V) comprises forming a conductor layer on the insulating layer.

[10] The method for manufacturing a wiring board according to any one of [1] to [9], comprising performing step (I), step (II), step (III), and step (IV) in this order at least twice.

[11] The method for manufacturing a wiring board according to any one of [1] to

[10] , wherein the thermoplastic film has a release layer.

[12] The method for producing a wiring board according to [2], wherein the resin composition contains a thermosetting resin.

[13] The method for producing a wiring board according to [2], wherein the resin composition contains an inorganic filler.

[0011] According to the present invention, a new manufacturing method can be provided that can easily manufacture a wiring board having an insulating layer in which a via hole or trench having a good cross-sectional shape is formed.

[0012] FIG. 1 is a cross-sectional view schematically illustrating an intermediate laminate prepared in step (I) of the method for manufacturing a wiring board according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating a preferred example of a method for manufacturing an intermediate laminate. FIG. 3 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view schematically illustrating step (III) of the method for manufacturing a wiring board according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view schematically illustrating a wiring board obtained by the method for manufacturing a wiring board according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to a second embodiment of the present invention. FIG. 9 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to the second embodiment of the present invention. FIG. 10 is a cross-sectional view schematically illustrating step (II) of the method for manufacturing a wiring board according to the second embodiment of the present invention. FIG. 11 is a cross-sectional view schematically illustrating step (III) of the method for manufacturing a wiring board according to the second embodiment of the present invention. Fig. 12 is a cross-sectional view schematically showing a wiring board obtained by the wiring board manufacturing method according to the second embodiment of the present invention. Fig. 13 is a cross-sectional view schematically showing step (II) of the wiring board manufacturing method according to the third embodiment of the present invention. Fig. 14 is a cross-sectional view schematically showing step (II) of the wiring board manufacturing method according to the third embodiment of the present invention. Fig. 15 is a cross-sectional view schematically showing step (II) of the wiring board manufacturing method according to the third embodiment of the present invention. Fig. 16 is a cross-sectional view schematically showing step (III) of the wiring board manufacturing method according to the third embodiment of the present invention. Fig. 17 is a cross-sectional view schematically showing a wiring board obtained by the wiring board manufacturing method according to the third embodiment of the present invention.

[0013] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with any modifications within the scope of the claims and their equivalents.

[0014] <Method for manufacturing a wiring board according to the first embodiment> The method for manufacturing a wiring board according to the first embodiment of the present invention includes the steps of (I) preparing a laminate having, in this order, a substrate, an insulating layer, and a thermoplastic film; (II) forming a recess in the thermoplastic film; (III) forming either or both of a via hole and a trench in the insulating layer by plasma treatment; and (IV) peeling off the thermoplastic film, in this order.

[0015] In the following description, the laminate prepared in step (I) may be referred to as an "intermediate laminate," the substrate provided in the intermediate laminate may be referred to as an "inner layer substrate," and the thermoplastic film provided in the intermediate laminate may be referred to as a "mask film." A resin film provided with a thermoplastic resin layer is typically used as the mask film. The recess formed in the mask film in step (II) refers to a portion that is recessed relative to the surrounding area, and includes both a depression that does not penetrate the mask film in the thickness direction and a through-hole that penetrates the mask film in the thickness direction.

[0016] In the wiring board manufacturing method according to the first embodiment, a recess is formed in the mask film in step (II). In the recess, the thickness of the mask film is relatively smaller than that of the non-recessed portion, or the mask film is absent. Therefore, when the insulating layer is subjected to plasma treatment in step (III), the mask film functions as a plasma mask, selectively removing the insulating layer below the recess, thereby forming a via hole and / or trench in that portion. Here, the "portion below the recess" of the insulating layer refers to the portion of the insulating layer corresponding to the recess, specifically, the portion of the insulating layer that is located at the same position as the recess when viewed from the thickness direction of the intermediate laminate. Therefore, the formed via hole and / or trench can have the same pattern shape as the pattern shape of the recess formed in the mask film. Unless otherwise specified, "pattern shape" refers to the shape viewed from the thickness direction. After forming one or both of the via hole and the trench in step (III), step (IV) is performed to peel off the mask film, resulting in a wiring board comprising an inner layer substrate and an insulating layer.

[0017] Generally, removal of a layer by plasma processing proceeds by scraping the layer in the thickness direction. Therefore, the insulating layer can be removed by plasma processing in the thickness direction in the portion below the recess. Therefore, the taper angle of the via hole and trench can be made close to 90°, thereby improving the cross-sectional shape of the via hole and trench. Depending on the cross-sectional shape of the recess formed in the mask film, a thin portion of the mask film may be formed around the recess. After the thin portion is scraped by plasma processing, the insulating layer below the thin portion may be scraped, and the taper angle may not be 90°. However, even in this case, it is possible to make the taper angle of the via hole and trench closer to 90° compared to conventional methods such as laser processing.

[0018] Furthermore, the mask film provided in the intermediate laminate is a resin film having a thermoplastic resin layer, and can usually have higher mechanical strength than a general plasma mask using a photoresist. Therefore, the mask film can be peeled off by simply pulling it, so no chemical treatment is required for peeling. Therefore, the number of steps can be reduced, and the wiring board can be easily manufactured. Furthermore, because chemical treatment is not required, chemical deterioration of the insulating layer due to chemicals can be suppressed, and as a result, a wiring board having an insulating layer with excellent insulating performance and electrical properties can be obtained.

[0019] Furthermore, conventionally, metal masks made of metal could be used as plasma masks. Generally, when forming the pattern shape of via holes and / or trenches, metal masks require patterning by exposure and development of a photosensitive material and etching of the metal with chemicals, which makes their production time-consuming, costly, and complicated. In contrast, the manufacturing method of the first embodiment using a mask film can easily accommodate changes in the pattern shape of via holes and / or trenches by changing the formation position of the recesses in the mask film. Therefore, in this sense, the manufacturing method of the first embodiment simplifies the manufacture of wiring boards.

[0020] Furthermore, according to the method for manufacturing a wiring board of the first embodiment, via holes and trenches having small openings can usually be formed. Specifically, this is as follows. Generally, recesses in a mask film are formed to have a bottom surface that is the same as or smaller than the opening of the recess. Furthermore, plasma processing can form via holes and / or trenches having openings that are the same as or smaller than the opening of the recess, specifically via holes and / or trenches having openings that are the same as or slightly larger than the bottom surface of the recess. Therefore, it is possible to manufacture wiring boards having fine circuit wiring, which can contribute to high integration.

[0021] Furthermore, according to the method for manufacturing a wiring board according to the first embodiment, it is possible to form via holes and trenches with small openings in an insulating layer that has excellent insulating performance and electrical properties. One of the advantages of the manufacturing method according to the first embodiment, which uses plasma processing, is that it is possible to achieve both an insulating layer that has excellent insulating performance and electrical properties and to form via holes and trenches with small openings in the insulating layer. The details are as follows.

[0022] Typically, insulating layers formed using thermosetting resin compositions tend to have excellent insulating performance and electrical properties. In particular, when using a thermosetting resin composition containing an inorganic filler, the linear thermal expansion coefficient of the insulating layer can be reduced, resulting in excellent insulating performance and electrical properties, as well as suppression of warping during temperature changes. In insulating layers formed using such thermosetting resin compositions, via holes and trenches have traditionally been formed by laser processing. However, laser processing can cause resin residue (smear) in the via holes and trenches, and unevenness can occur in the via holes and trenches during the process of removing the resin residue, making it difficult to reduce the openings of these via holes and trenches. In particular, when using a resin composition containing an inorganic filler, it is particularly difficult to reduce the opening diameter.

[0023] As a method for simply forming an insulating layer having a small opening such as a via hole or trench, a method for forming an insulating layer using a photosensitive resin composition by photolithography has been known. However, it has been difficult to improve the insulating performance and electrical properties of an insulating layer using a photosensitive resin composition.

[0024] In contrast, in the manufacturing method according to the first embodiment, the insulating layer can be formed using a material other than a photosensitive resin composition, and therefore the insulating layer can be formed using a material with excellent insulating performance and electrical properties (for example, a cured product of a thermosetting resin composition). Therefore, it is possible to form via holes and trenches with small openings in the insulating layer with excellent insulating performance and electrical properties.

[0025] Furthermore, according to the manufacturing method of the first embodiment, plasma processing is performed using the mask film as a plasma mask, so that it is easy to align the recesses in the mask film with the via holes and trenches formed in the insulating layer.

[0026] Furthermore, as described above, resin residues are generated in via holes and trenches formed by conventional methods using exposure and development. Therefore, in order to remove the resin residues, conventional methods generally involve performing a desmear treatment using an oxidizing agent solution after the via holes or trenches are formed.

[0027] In contrast, when via holes and / or trenches are formed by plasma treatment as employed in the manufacturing method according to the first embodiment, the generation of resin residues can be suppressed. Specifically, plasma treatment can reduce the amount of resin residue generated, and preferably eliminates the generation of resin residues. Therefore, the manufacturing method according to the first embodiment does not require a desmear treatment using an oxidizer solution. Because desmear treatment using an oxidizer solution is not required, the manufacturing method according to the first embodiment allows for the production of wiring boards by a dry process. For example, when an intermediate laminate is manufactured by a dry manufacturing method including laminating a resin sheet and an inner layer substrate and curing the resin composition layer of the resin sheet, the intermediate laminate can be prepared by a dry process in step (I). Furthermore, when dry recess formation methods such as laser processing and imprinting are used, recesses can be formed in the mask film by a dry process in step (II). Furthermore, when dry conductor layer formation processes such as sputtering and vapor deposition are used, a conductor layer can be formed by a dry process in step (V). Therefore, when these steps are combined with step (III) of forming via holes and / or trenches by plasma treatment, steps (I) to (V) can be carried out dry to achieve the manufacture of a wiring board by a dry process.

[0028] Furthermore, in a conventional desmear treatment using an oxidizer solution, the surface of the insulating layer is generally roughened by the oxidizer solution, resulting in an increase in the surface roughness of the insulating layer. In contrast, the plasma treatment employed in the first embodiment does not require the desmear treatment, and therefore, an increase in the surface roughness of the insulating layer can be suppressed. Therefore, in the wiring board manufactured by the manufacturing method according to the above-described embodiment, the surface roughness of the insulating layer can be reduced, thereby reducing the transmission loss of the conductor layer formed on the surface of the insulating layer.

[0029] <Step (I): Preparation of intermediate laminate> The method for manufacturing a wiring board according to the first embodiment includes step (I) of preparing an intermediate laminate. Figure 1 is a cross-sectional view schematically showing an intermediate laminate 10 prepared in step (I) of the method for manufacturing a wiring board according to the first embodiment of the present invention. As shown in Figure 1, in step (I), an intermediate laminate 10 is prepared which includes an inner layer substrate 100, an insulating layer 200, and a mask film 300 in this order in the thickness direction.

[0030] -Inner layer substrate 100- As the inner layer substrate 100, a member having a support substrate 110 capable of supporting the inner layer substrate 100 is usually used. Examples of the support substrate 110 include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate.

[0031] The inner substrate 100 may include a conductor layer 120. Hereinafter, this conductor layer 120 may be referred to as an "inner conductor layer" 120. The inner conductor layer 120 may generally form the circuit wiring of the wiring board. The inner conductor layer 120 may be formed inside the support substrate 110, or may be formed on the surface of the support substrate 110. In the first embodiment, an example in which the inner conductor layer 120 is formed on the surface of the support substrate 110 will be described. When a via hole is formed in step (III), the via hole is usually formed so that the inner conductor layer 120 appears at the bottom of the via hole.

[0032] The inner conductor layer 120 typically contains a conductive material. For example, the same conductive material as the conductor layer (circuit conductor layer) that can be formed in step (V) described below can be used. The inner conductor layer 120 may have a single-layer structure, or a multi-layer structure including two or more single-metal layers or alloy layers made of different types of metals or alloys. The thickness of the inner conductor layer 120 depends on the desired wiring board design, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0033] In order to utilize the advantage of this embodiment, namely, the ability to reduce the dimensions of via hole and trench openings, when the inner conductor layer 120 forms circuit wiring, the minimum line / space ratio of the inner conductor layer 120 is preferably small. Unless otherwise specified, "line" refers to the wiring width, and "space" refers to the spacing between wirings. The minimum line / space ratio of the inner conductor layer 120 is preferably 5 μm / 5 μm or less, more preferably 4 μm / 4 μm or less, and even more preferably 3 μm / 3 μm or less, and is preferably 0.1 μm / 0.1 μm or more, more preferably 0.5 μm / 0.5 μm or more, and even more preferably 1 μm / 1 μm or more. Furthermore, the wiring pitch of the inner conductor layer 120 is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less, and is preferably 0.2 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. The line / space ratio and wiring pitch may each be uniform or non-uniform throughout the inner conductor layer 120 .

[0034] The inner conductor layer 120 can be formed, for example, by the same method as the method for forming the circuit conductor layer in step (V) described below.

[0035] - Insulating layer 200 - The insulating layer 200 is formed on the inner substrate 100. The insulating layer 200 may be provided on one side or both sides of the inner substrate 100. Typically, the insulating layer 200 is formed so as to be in direct contact with the inner substrate 100. Here, "direct" contact between two components means that there is no other component between the two components. When the inner substrate 100 includes an inner conductor layer 120 as the outermost layer, the insulating layer 200 can be formed so as to be in direct contact with the inner conductor layer 120.

[0036] The insulating layer 200 is an insulating layer, and is generally formed from a cured product of a resin composition. Therefore, the insulating layer 200 includes a cured product of a resin composition, and preferably includes only a cured product of the resin composition. As the resin composition, a material containing (A) a curable resin and, as necessary, any optional components can be used. As the resin composition, a photocurable resin composition or a thermosetting resin composition may be used. Among these, a thermosetting resin composition is preferred from the viewpoint of improving the dielectric properties of the insulating layer 200.

[0037] Examples of the (A) curable resin as the (A) component include a thermosetting resin and a photocurable resin. As the (A) curable resin, only a thermosetting resin may be used, only a photocurable resin may be used, or a combination of a thermosetting resin and a photocurable resin may be used. From the viewpoint of obtaining an insulating layer 200 with excellent dielectric properties, it is preferable that the (A) curable resin contains a thermosetting resin. One type of (A) curable resin may be used alone, or two or more types may be used in combination.

[0038] The thermosetting resin may be a resin that can be cured when heat is applied. Examples of the thermosetting resin include epoxy resin, phenol resin, active ester resin, cyanate ester resin, carbodiimide resin, acid anhydride resin, amine resin, benzoxazine resin, polyarylene ether resin, and radical polymerizable resin. One type of thermosetting resin may be used alone, or two or more types may be used in combination.

[0039] From the viewpoint of improving adhesion between the insulating layer 200 and a circuit conductor layer that may be formed on the insulating layer 200, it is preferable that the curable resin (A) contains a combination of an epoxy resin and a resin that can react with the epoxy resin to cure the resin composition. Hereinafter, a resin that can react with an epoxy resin to cure the resin composition may be referred to as a "curing agent." Examples of curing agents include phenolic resins, active ester resins, cyanate ester resins, carbodiimide resins, acid anhydride resins, amine resins, and benzoxazine resins. One type of curing agent may be used alone, or two or more types may be used in combination. For example, a phenolic resin and an active ester resin may be used in combination as the curing agent.

[0040] Epoxy resins are curable resins having epoxy groups. Examples of epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, and tetraphenylethane-type epoxy resins. The epoxy resin may be used alone or in combination of two or more kinds.

[0041] The curable resin preferably contains an epoxy resin having two or more epoxy groups per molecule, and the proportion of the epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to 100% by mass of the non-volatile components of the epoxy resin.

[0042] Epoxy resins include epoxy resins that are liquid at a temperature of 20° C. (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20° C. (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only a liquid epoxy resin as the epoxy resin, or may contain only a solid epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0043] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0044] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure, with cyclohexane type epoxy resins being more preferred.

[0045] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "jER828EL", "825", and "Epikote 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "630" and "630LSD" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation. ); "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Corporation; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Corporation. These may be used alone or in combination of two or more.

[0046] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0047] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, and tetraphenylethane-type epoxy resins, and more preferred are bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthylene ether-type epoxy resins, and bisphenol AF-type epoxy resins.

[0048] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", and "HP-7200H" manufactured by DIC Corporation. dicyclopentadiene type epoxy resin); "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", and "HP6000L" (naphthylene ether type epoxy resins) manufactured by DIC Corporation; "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "N C3000H, NC3000, NC3000L, NC3100 (biphenyl type epoxy resin); Nippon Steel Chemical & Material's "ESN475V" (naphthalene type epoxy resin); Nippon Steel Chemical & Material's "ESN485" (naphthol novolac type epoxy resin); Mitsubishi Chemical's "YX4000H" and "YX4000HK" (bixylenol type epoxy resin); Mitsubishi Chemical's "YX8800" (a Examples of such epoxy resins include bisphenol A epoxy resins (tetraphenylene type epoxy resins), PG-100 and CG-500 manufactured by Osaka Gas Chemicals Co., Ltd., YL7760 manufactured by Mitsubishi Chemical Corporation (bisphenol AF type epoxy resin), YL7800 manufactured by Mitsubishi Chemical Corporation (fluorene type epoxy resin), jER1010 manufactured by Mitsubishi Chemical Corporation (solid bisphenol A type epoxy resin), and jER1031S manufactured by Mitsubishi Chemical Corporation (tetraphenylethane type epoxy resin). These may be used alone or in combination of two or more.

[0049] When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 1:0.1 to 1:20, more preferably 1:0.3 to 1:18, and particularly preferably 1:0.5 to 1:15. When the mass ratio of the liquid epoxy resin to the solid epoxy resin is within this range, the resin composition layer of the resin sheet can have appropriate adhesiveness and sufficient flexibility, thereby improving the handleability of the resin sheet. Furthermore, an insulating layer 200 having sufficient breaking strength can usually be obtained.

[0050] The epoxy equivalent of the epoxy resin is preferably in the range of 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., even more preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

[0051] The weight average molecular weight (Mw) of the epoxy resin is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0052] The amount of the epoxy resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0053] The amount of the epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. Unless otherwise specified, the resin components of the resin composition refer to the non-volatile components of the resin composition excluding the inorganic filler (B) described below.

[0054] As the phenolic resin, a compound having one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule can be used. From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. From the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among these, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion. Specific examples of phenolic resins include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "TD-2090", "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", "TD-2090-60M", and "EXB-9500" manufactured by DIC Corporation.

[0055] The amount of the phenolic resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0056] The amount of the phenolic resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0057] As the active ester resin, a resin having one or more active ester groups per molecule can be used. Among these, preferred active ester resins are those having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The active ester resin is preferably one 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, active ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and active ester resins obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound are more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, etc. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0058] Preferred specific examples of the active ester resin include active ester resins containing a dicyclopentadiene-type diphenol structure, active ester resins containing a naphthalene structure, active ester resins containing an acetylated product of phenol novolac, and active ester resins containing a benzoylated product of phenol novolac. Among these, active ester resins containing a naphthalene structure and active ester resins containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0059] Commercially available activated ester resins include, for example, activated ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", and "EXB-8000L-65TM" (manufactured by DIC Corporation); and naphthalene-type activated ester resins containing a naphthalene structure such as "HP-B-8151-62T", "EXB9416-70BK", "EXB-8100L-65T", "EXB-8150L-65T", "EXB-8150-65T", "HPC-8150-60T", and "HPC-8150-62T" (manufactured by DIC Corporation). 02-65T" (manufactured by Air Water Inc.); an activated ester resin containing an acetylated product of phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin containing a benzoylated product of phenol novolac is "YLH1026" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin which is an acetylated product of phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester resins which are benzoylated products of phenol novolac are "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and "EXB-8500-65T" (manufactured by DIC Corporation).

[0060] The amount of the active ester resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0061] The amount of the active ester resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0062] Examples of cyanate ester resins, carbodiimide resins, acid anhydride resins, amine resins, and benzoxazine resins include those described in JP-A-2020-75977.

[0063] The range of the active group equivalent of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the curing agent per equivalent of the active group.

[0064] When the number of epoxy groups in the epoxy resin is taken as 1, the range of the number of active groups in the curing agent is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.2 or more, and preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less. The "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition by the epoxy equivalent. Furthermore, the "number of active groups in the curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the active group equivalent.

[0065] The amount of the curing agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0066] The range of the amount of the curing agent is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, relative to 100% by mass of the resin component in the resin composition.

[0067] As the polyarylene ether resin, a resin having a polyarylene ether skeleton and a functional group capable of reacting with heat to form a bond can be used. An example of the functional group is a hydroxy group. The polyarylene ether resin preferably has a functional group such as a hydroxy group at its terminal. Examples of the polyarylene ether resin include polyphenylene ether resin and polynaphthylene ether resin, which may be a homopolymer or a copolymer. Among the polyphenylene ether resins, examples of the homopolymer include 2,6-diC １～３ Examples of copolymers include those containing alkyl-1,4-phenylene ether units. １～３ Alkyl-1,4-phenylene ether units and 2,3,6-triC １～３ Examples include those containing a combination of alkyl-1,4-phenylene ether units. １～３ Unless otherwise specified, "alkyl" refers to alkyl having 1 to 3 carbon atoms. The copolymer may be any of a graft copolymer, a block copolymer, and a random copolymer. An example of a commercially available polyarylene ether resin is "Noryl (registered trademark) SA90" manufactured by SABIC.

[0068] The number average molecular weight (Mn) of the polyarylene ether resin is preferably 200 to 5,000, more preferably 400 to 3,000, and even more preferably 600 to 2500. The Mn of the polyarylene ether resin can be measured by a GPC method as a polystyrene-equivalent value.

[0069] The radical polymerizable resin may be a resin having one or more (preferably two or more) radical polymerizable unsaturated groups per molecule. Examples of the radical polymerizable unsaturated group include a maleimide group, a vinyl group, an allyl group, a styryl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, a fumaroyl group, and a maleoyl group. The radical polymerizable resin may have one type of radical polymerizable unsaturated group alone, or two or more types in combination. From the viewpoint of obtaining an insulating layer 200 that exhibits both good insulating properties and good heat resistance, the radical polymerizable resin preferably includes one or more types selected from a maleimide resin, a (meth)acrylic resin, and a styryl resin.

[0070] As the maleimide resin, a resin having one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) per molecule can be used. Commercially available maleimide resins include, for example, "BMI-3000J," "BMI-5000," "BMI-1400," "BMI-1500," "BMI-1700," and "BMI-689" (all manufactured by Designer Molecules). Examples of suitable maleimide resins include maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton containing a cyclic structure having 10 or more carbon atoms, more preferably an aliphatic skeleton having 36 carbon atoms derived from dimer diamine), such as maleimide resins manufactured by Nippon Kayaku Co., Ltd.; maleimide resins containing an indane skeleton, as described in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211; and maleimide resins containing an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group, such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000," "BMI-1000" (manufactured by Daiwa Kasei Co., Ltd.), and "BMI-80" (manufactured by Keiai Kasei Co., Ltd.).

[0071] As the (meth)acrylic resin, a resin having one or more (preferably two or more) (meth)acryloyl groups per molecule can be used. The (meth)acrylic resin may be a monomer or an oligomer. The term "(meth)acryloyl group" is a general term for acryloyl groups and methacryloyl groups. Examples of (meth)acrylic resins include (meth)acrylate monomers. Examples of commercially available (meth)acrylic resins include "A-DOG" (manufactured by Shin-Nakamura Chemical Co., Ltd.); "DCP-A" (manufactured by Kyoeisha Chemical Co., Ltd.); "NPDGA," "FM-400," "R-687," "THE-330," "PET-30," and "DPHA" (all manufactured by Nippon Kayaku Co., Ltd.).

[0072] As the styryl resin, a resin having one or more (preferably two or more) styryl groups or vinylphenyl groups per molecule can be used. The styryl resin may be a monomer or an oligomer. Examples of the styryl resin include "OPE-2St," "OPE-2St 1200," and "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company, Inc.). Styrene monomers may also be used as the styryl resin. Further examples of the styryl resin include homopolymers of aromatic divinyl compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; and copolymers of these aromatic divinyl compounds with aromatic monovinyl compounds such as styrene, vinyltoluene, ethylstyrene, and vinylnaphthalene.

[0073] The weight average molecular weight (Mw) of the radical polymerizable resin is preferably 40,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but may be, for example, 150 or more.

[0074] The range of the amount of (A) curable resin is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of non-volatile components in the resin composition, and is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0075] The range of the amount of (A) the curable resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 99% by mass or less.

[0076] The resin composition may contain an inorganic filler (B) as an optional component. The inorganic filler (B) as the (B) component is typically contained in the resin composition in the form of particles and can be contained in the insulating layer 200 while maintaining its particulate form. In conventional laser processing and drilling methods for forming via holes and trenches, the particles of the inorganic filler (B) themselves are not processed during the formation of the via holes and trenches, which tends to result in a small taper angle. Furthermore, the detachment of the inorganic filler particles (B) tends to increase the surface roughness of the walls of the via holes and trenches. In contrast, plasma treatment can remove the particles of the inorganic filler (B) itself, thereby forming via holes and trenches while suppressing the detachment of the inorganic filler particles (B). Therefore, according to the manufacturing method of the first embodiment, the taper angle can be effectively increased even when using a resin composition containing the inorganic filler (B). Therefore, from the perspective of effectively utilizing these advantages, it is preferable that the resin composition contain the inorganic filler (B). The inorganic filler (B) may be used alone or in combination of two or more.

[0077] (B) Inorganic filler materials can be inorganic compounds. (B) Examples of inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Furthermore, spherical silica is preferred.

[0078] (B) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; and "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation.

[0079] (B) The specific surface area of ​​the inorganic filler is preferably 1 m ２ / g or more, more preferably 2m ２ / g or more, more preferably 3m ２ / g or more. There is no particular upper limit, but it is preferably 60 m ２ / g or less, 50m ２ / g or less or 40m ２The specific surface area can be measured by a BET multipoint method using a fully automatic BET specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) with nitrogen gas adsorbed onto the surface of the sample.

[0080] The average particle size of the inorganic filler (B) is preferably 0.01 μm or more, more preferably 0.03 μm or more, particularly preferably 0.05 μm or more, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0081] The average particle size of the (B) inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution of the (B) inorganic filler is prepared on a volume basis using a laser diffraction / scattering particle size distribution measuring device, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The measurement sample is measured using a laser diffraction particle size distribution measuring device, with blue and red light source wavelengths used, using a flow cell system to measure the volume-based particle size distribution of the inorganic filler, and the average particle size can be calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction particle size distribution measuring device is the "LA-960" manufactured by Horiba, Ltd.

[0082] In order to improve moisture resistance and dispersibility, the (B) inorganic filler is preferably treated with a surface treatment agent. Examples of the surface treatment agent include vinylsilane coupling agents, (meth)acrylic coupling agents, fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, and titanate coupling agents. One type of surface treatment agent may be used alone, or two or more types may be used in combination.

[0083] Commercially available surface treatment agents include, for example, Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM503" (3-methacryloxypropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), and Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane). Examples of suitable silane coupling agents include "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent), and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0084] The degree of surface treatment with the surface treatment agent preferably falls within a specific range from the viewpoint of improving the dispersibility of the (B) inorganic filler. Specifically, 100 parts by mass of the (B) inorganic filler is preferably surface-treated with 0.2 to 5 parts by mass of the surface treatment agent, more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 2 parts by mass.

[0085] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the (B) inorganic filler. From the viewpoint of improving the dispersibility of the (B) inorganic filler, the amount of carbon per unit surface area of ​​the (B) inorganic filler is 0.02 mg / m ２ More than 0.1 mg / m ２ More preferably, 0.2 mg / m or more ２ On the other hand, from the viewpoint of suppressing an increase in the melt viscosity of the resin varnish and the melt viscosity in the form of a sheet, it is more preferable that the amount of the resin varnish is 1 mg / m ２ Preferably, 0.8 mg / m or less ２ More preferably, 0.5 mg / m or less ２ The following is even more preferred:

[0086] The carbon amount per unit surface area of ​​the (B) inorganic filler can be measured after the surface-treated (B) inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with the surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the carbon amount per unit surface area of ​​the (B) inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, an "EMIA-320V" manufactured by Horiba, Ltd. or the like can be used.

[0087] The range of the amount of (B) inorganic filler is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less.

[0088] The resin composition may contain a (C) curing accelerator as an optional component. The (C) curing accelerator can function as a catalyst for the curing reaction of the (A) curable resin. Unless otherwise specified, the (C) curing accelerator does not include components corresponding to the above-mentioned components (A) to (B). Examples of the (C) curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Among these, amine-based curing accelerators are preferred. One type of (C) curing accelerator may be used alone, or two or more types may be used in combination.

[0089] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

[0090] Other examples of the curing accelerator (C) include those described in JP-A-2020-75977.

[0091] The amount of (C) curing accelerator is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more, relative to 100% by mass of non-volatile components in the resin composition, and is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.

[0092] The amount of (C) curing accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less.

[0093] The resin composition may contain a (D) thermoplastic resin as an optional component. Unless otherwise specified, the (D) thermoplastic resin as component (D) does not include the components corresponding to the above-mentioned (A) to (C) components. Examples of the (D) thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polyimide resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polyetheretherketone resin, and polyester resin, with phenoxy resin being preferred. One type of thermoplastic resin may be used alone, or two or more types may be used in combination.

[0094] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of 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 skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. One type of phenoxy resin may be used alone, or two or more types may be used in combination. Specific examples of phenoxy resins include "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton), all manufactured by Mitsubishi Chemical Corporation. Other examples include "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd., and "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0095] Other examples of the thermoplastic resin (D) include those described in JP-A-2020-75977.

[0096] The weight average molecular weight of the thermoplastic resin (D) is usually greater than 5,000, preferably at least 8,000, more preferably at least 10,000, and even more preferably at least 20,000. The upper limit is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and particularly preferably 50,000 or less.

[0097] The amount of (D) thermoplastic resin is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more, relative to 100% by mass of non-volatile components in the resin composition, and is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0098] The amount of the (D) thermoplastic resin is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0099] The resin composition may further contain an optional additive (E) as an optional component. Examples of the optional additive (E) as the component (E) include a polymerization initiator, an organometallic compound, a colorant, a polymerization inhibitor, a leveling agent, a thickener, an antifoaming agent, an ultraviolet absorber, an adhesion improver, an adhesion imparting agent, an antioxidant, a fluorescent brightener, a surfactant, a flame retardant, a dispersant, a stabilizer, a photopolymerization initiation aid, and a photosensitizer. One type of optional additive (E) may be used alone, or two or more types may be used in combination.

[0100] The resin composition may further contain a solvent (F) as a volatile component in addition to the nonvolatile components (A) to (E) described above. Examples of the (F) solvent include ketone solvents such as methyl ethyl ketone (MEK) and cyclohexanone; aromatic hydrocarbon solvents such as xylene and tetramethylbenzene; glycol ether solvents such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ester solvents such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate; aliphatic hydrocarbon solvents such as octane and decane; petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; and ether ester solvents such as propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. The solvent (F) may be used alone or in combination of two or more.

[0101] The resin composition may contain a (F) solvent, but the amount of the (F) solvent is preferably small. The amount of the (F) solvent contained in the resin composition is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition. The lower limit of the amount of the (F) solvent may be 0% by mass or more than 0% by mass, based on 100% by mass of the nonvolatile components in the resin composition.

[0102] The above-described resin composition can usually be cured to give a cured product having excellent dielectric properties, and therefore, the insulating layer 200 formed from the cured product of the resin composition can have excellent dielectric properties.

[0103] Specifically, the dielectric constant of the insulating layer 200 is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.5 or less. The lower limit of the dielectric constant is not particularly limited, but may be, for example, 0.0001 or more. The dielectric loss tangent of the insulating layer 200 is preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less. The lower limit of the dielectric loss tangent is not particularly limited, but may be, for example, 0.0005 or more. The dielectric constant and dielectric loss tangent can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. As a measuring device, for example, an "HP8362B" manufactured by Agilent Technologies can be used.

[0104] From the viewpoint of thinning the wiring board, the thickness of the insulating layer 200 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, and may be 30 μm or less or 20 μm or less. The lower limit of the thickness of the insulating layer 200 is not particularly limited, and may be, for example, 1 μm or more, 3 μm or more, etc.

[0105] -Mask film 300- The mask film 300 is formed on the insulating layer 200. Typically, the mask film 300 is formed so as to be in direct contact with the insulating layer 200. The mask film 300 is a film including a thermoplastic resin layer 310, and can function as a mask (plasma mask) for the plasma treatment in step (III).

[0106] The thermoplastic resin layer 310 is a layer that supports the mask film 300, and can usually function as a base material for the mask film 300. The thermoplastic resin layer 310 contains a thermoplastic resin, or may contain only a thermoplastic resin. A thermoplastic resin film containing a thermoplastic resin may be used as the thermoplastic resin layer 310.

[0107] Examples of thermoplastic resins contained in the thermoplastic resin layer 310 include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic polymers such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate, polyethylene naphthalate, and polyimide are preferred, and polyethylene naphthalate and polyimide are more preferred. One type of thermoplastic resin may be used alone, or two or more types may be used in combination.

[0108] The thermoplastic resin contained in the thermoplastic resin layer 310 preferably has a glass transition temperature lower than that of a cured product of the resin composition that can be contained in the insulating layer. Specifically, the difference between the glass transition temperature of the thermoplastic resin contained in the thermoplastic resin layer 310 and that of a cured product of the resin composition that can be contained in the insulating layer 200 is preferably 0.5°C or higher, more preferably 1°C or higher, even more preferably 5°C or higher, and preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. When the glass transition temperature of the thermoplastic resin contained in the thermoplastic resin layer 310 is lower than that of a cured product of the resin composition that can be contained in the insulating layer 200, recesses can be smoothly formed in the mask film 300 using an imprint method in step (II). The glass transition temperature can be measured using a thermomechanical analyzer (DMA) in "tensile mode" from 25°C to 240°C at a heating rate of 2°C / min. The temperature at which the loss tangent (tan δ), calculated as the ratio of the measured storage modulus (E') to the loss modulus (E"), reaches a maximum value, is defined as the glass transition temperature.

[0109] The thermoplastic resin contained in the thermoplastic resin layer 310 preferably has a linear thermal expansion coefficient similar to that of the cured product of the resin composition that can be contained in the insulating layer 200. Specifically, the absolute value of the difference between the linear thermal expansion coefficient of the thermoplastic resin contained in the thermoplastic resin layer 310 and the linear thermal expansion coefficient of the cured product of the resin composition that can be contained in the insulating layer 200 is preferably 60 ppm / °C or less, more preferably 55 ppm / °C or less, and even more preferably 50 ppm / °C or less. There is no particular lower limit, and it can be, for example, 0 ppm / °C or more, 0.5 ppm / °C or more, or 1 ppm / °C or more. When the linear thermal expansion coefficient of the thermoplastic resin contained in the thermoplastic resin layer 310 is similar to that of the cured product of the resin composition that can be contained in the insulating layer 200, the difference in expansion between the mask film 300 and the insulating layer 200 during the plasma treatment in step (III) can be reduced. Therefore, the influence of thermal expansion due to the plasma treatment can be reduced, and the taper angle, position, and dimensions of the via hole and / or trench can be prevented from deviating significantly from the design values. The linear thermal expansion coefficient can be measured by thermomechanical analysis using a tensile load method using a thermomechanical analyzer (Rigaku's "Thermo Plus TMA8310"). Specifically, after loading a sample into the thermomechanical analyzer, thermomechanical analysis is performed twice consecutively under measurement conditions of a load of 1 g and a heating rate of 5°C / min (the first time the temperature is raised to 200°C, and the second time the temperature is raised to 260°C). In the second measurement, the average linear thermal expansion coefficient (CTE; ppm / °C) in the range from 25°C to 150°C can be calculated as the linear thermal expansion coefficient of the cured product and the thermoplastic resin.

[0110] The thickness of the thermoplastic resin layer 310 is not limited as long as it allows the desired via holes and / or trenches to be formed in the insulating layer 200. In one example, the specific range of the thickness of the thermoplastic resin layer 310 is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, even more preferably 14 μm or more, even more preferably 15 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, even more preferably 40 μm or less, and even more preferably 30 μm or less.

[0111] The mask film 300 may include an optional layer (not shown) in combination with the thermoplastic resin layer 310. The optional layer is preferably a layer containing a material that can be removed by the plasma treatment in step (III). However, even if the optional layer is made of a material that is difficult to remove by plasma treatment (e.g., a metal layer), it can be used as the optional layer as long as it can be removed when forming the recesses in step (II).

[0112] An example of an optional layer that can be provided on the mask film 300 is a release layer. The release layer can be formed so as to bond to the insulating layer 200 with a release agent. By using the mask film 300 that has the release layer, the mask film 300 can be smoothly peeled off in the step (IV).

[0113] Examples of release agents include alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available products may be used as the masking film 300 having such a release layer. For example, PET films having a release layer primarily composed of an alkyd resin-based release agent, such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, and "Uni-Peel" manufactured by Unitika Ltd., may be used as the masking film 300.

[0114] The thickness of the release layer is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more, and is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. Furthermore, when using a mask film 300 having a release layer, the range of the total thickness of the thermoplastic resin layer 310 and the release layer may be the same as the range of the thickness of the thermoplastic resin layer 310 described above.

[0115] An example of an optional layer that may be provided on the mask film 300 is a barrier layer. The barrier layer can suppress the transmission of water vapor through the mask film 300. When using a mask film 300 that includes a release layer, the barrier layer may be formed on the opposite side of the thermoplastic resin layer 310 from the release layer.

[0116] The barrier layer may be an inorganic film, an organic film, or a composite film containing a combination of an inorganic film and an organic film. Examples of inorganic films include metal foils such as aluminum and copper; silica vapor deposition films; silicon nitride films; silicon oxide films; and magnesium oxide films. Examples of methods for forming inorganic films include chemical vapor deposition using heat, plasma, ultraviolet light, or the like; and physical vapor deposition using deposition, sputtering, or the like. Examples of organic films include polyvinyl alcohol films, ethylene-vinyl alcohol copolymer films, and polyvinylidene chloride films. Examples of methods for forming organic films include coating an organic compound onto the thermoplastic resin layer 310 using a coating device such as a die coater, comma coater, gravure coater, or bar coater.

[0117] The thickness of the barrier layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.4 μm or more, even more preferably 0.5 μm or more, even more preferably 0.6 μm or more, even more preferably 0.8 μm or more, even more preferably 1 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less.

[0118] An optional layer that may be provided on the mask film 300 includes, for example, an adhesive layer. For example, an adhesive layer may be provided between the thermoplastic resin layer 310 and the barrier layer. Examples of adhesives that may be used for the adhesive layer include water-based adhesives, solvent-based adhesives, hot-melt adhesives, and active energy ray-curable adhesives that can be cured by active energy rays such as ultraviolet rays. The thickness of the adhesive layer is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0119] The mask film 300 typically has higher mechanical strength than conventional masks using photosensitive resin compositions such as photoresists. Therefore, the mask film 300 can be simply pulled and peeled off in step (IV). In one example, the tensile modulus of the mask film 300 is preferably 100 MPa or more, more preferably 500 MPa or more, and even more preferably 1000 MPa or more, and is preferably 30 GPa or less, more preferably 20 GPa or less, and even more preferably 15 GPa or less. The tensile modulus of the film can be measured at 23°C in accordance with JIS K7127.

[0120] The total thickness of the mask film 300 is not limited as long as it allows the desired via holes and / or trenches to be formed in the insulating layer 200. From the viewpoint of preventing via holes and masks from being formed in areas other than the areas below the recesses in step (III), the total thickness of the mask film 300 is preferably greater than the thickness of the insulating layer 200. In one example, the specific range of the total thickness of the mask film 300 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 80 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less.

[0121] The surface of the mask film 300 facing the insulating layer 200 may be subjected to a surface treatment such as matte treatment, corona treatment, or antistatic treatment.

[0122] -Method for manufacturing intermediate laminate 10- In step (I), for example, the intermediate laminate 10 may be prepared by purchasing it from the market, or by manufacturing it. When manufacturing the intermediate laminate 10, there are no limitations on the manufacturing method. For example, when the insulating layer 200 is formed from a cured product of a resin composition, step (I) may manufacture the intermediate laminate 10 by a method including: step (I-1) of forming a resin composition layer on the inner layer substrate 100; and step (I-2) of curing the resin composition layer.

[0123] When an intermediate laminate is produced by a method including the above-described steps (I-1) and (I-2), step (I) may include, in this order, step (I-1) of forming a resin composition layer on the inner layer substrate 100, step (I-2) of laminating the resin composition layer and the mask film 300, and step (I-2) of curing the resin composition layer to form an insulating layer. In this case, step (I-1) may include, in this order, applying a resin composition to the inner layer substrate 100 and drying the applied resin composition as necessary.

[0124] From the viewpoint of reducing the number of steps and easily producing the intermediate laminate 10, it is preferable that step (I) includes forming a resin composition layer on the inner layer substrate 100 using a resin sheet including a mask film 300 and a resin composition layer, and then curing the resin composition layer to form the insulating layer 200. The operation of this preferable step (I) will be described below.

[0125] Fig. 2 is a schematic cross-sectional view illustrating a preferred example of a method for producing the intermediate laminate 10. As shown in Fig. 2, in the preferred example of the method for producing the intermediate laminate 10, step (I-1) includes laminating a resin sheet 20 including a mask film 300 and a resin composition layer 210 and an inner layer substrate 100 such that the resin composition layer 210 and the inner layer substrate 100 are bonded to each other.

[0126] The resin sheet 20 includes a mask film 300 and a resin composition layer 210 formed on the mask film 300. When the mask film 300 includes a release layer (not shown), the resin composition layer 210 is usually formed so as to be in direct contact with the release layer.

[0127] The resin composition layer 210 includes the above-described resin composition, and preferably includes only the resin composition. The thickness range of the resin composition layer 210 may be the same as the thickness range of the insulating layer 200.

[0128] The resin sheet 20 can be manufactured, for example, by a method including preparing a resin composition and forming a resin composition layer 210 containing the resin composition on a mask film 300. The resin composition can be manufactured, for example, by mixing components that can be contained in the resin composition. Typically, the resin composition is manufactured by mixing non-volatile components such as components (A) to (E) and a solvent (F). The components may be mixed in part or all at the same time, or may be mixed sequentially. The temperature may be set appropriately during the process of mixing each component, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed during the process of mixing each component.

[0129] When the prepared resin composition is in a liquid state, the resin composition layer can be formed by applying the resin composition onto the mask film 300. If necessary, the resin composition and a solvent may be mixed to prepare a resin varnish as a liquid resin composition, and the resin varnish may be applied onto the mask film 300 to form a resin composition layer. Examples of the solvent include those similar to the solvent (F) described as a component of the resin composition. Drying may be performed after application.

[0130] Examples of methods for applying the resin composition include wire bar coating, reverse coating, gravure coating, die coating, blade coating, dip coating, air knife coating, curtain coating, and roller coating, with die coating being preferred.

[0131] Drying may be performed by a drying method such as heating or hot air blowing. Drying conditions may be set so that the solvent content in the resin composition layer 210 is typically 10% by mass or less, preferably 5% by mass or less. For example, when a resin composition containing 30% by mass to 60% by mass of solvent is used, the resin composition layer 210 may be formed by drying at 50°C to 150°C for 1 minute to 10 minutes.

[0132] In the resin sheet 20, a protective film (not shown) similar to the mask film 300 may be further provided on the surface of the resin composition layer 210 that is not bonded to the mask film 300 (i.e., the surface opposite to the mask film 300). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By providing the protective film, it is possible to prevent dust from adhering to and scratches on the surface of the resin composition layer 210. The resin sheet 20 can be stored in a rolled state. When the resin sheet 20 has a protective film, the resin sheet 20 can be used by peeling off the protective film.

[0133] In a preferred example of the method for manufacturing the intermediate laminate 10, as shown in Figure 2, step (I-1) includes preparing a resin sheet 20 and then laminating the resin sheet 20 and the inner layer substrate 100 so that the resin composition layer 210 and the inner layer substrate 100 are bonded.

[0134] The resin sheet 20 and the inner substrate 100 can be laminated together, for example, by thermocompression bonding the resin sheet 20 to the inner substrate 100 from the mask film 300 side. Examples of a member for thermocompression bonding the resin sheet 20 to the inner substrate 100 (hereinafter also referred to as a "thermocompression member"; not shown) include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). In this case, the thermocompression member may be pressed directly onto the resin sheet 20, or may be pressed via an elastic material (not shown) such as heat-resistant rubber so that the resin sheet 20 can sufficiently conform to the surface irregularities of the inner substrate 100.

[0135] The resin sheet 20 and the inner layer substrate 100 may be laminated by a vacuum lamination method. Under the thermocompression bonding conditions of the vacuum lamination method, the thermocompression bonding temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C. The thermocompression bonding pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa. The thermocompression bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination may be performed under reduced pressure conditions, preferably a pressure of 26.7 hPa or less.

[0136] The lamination can be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0137] Step (I-1) may include, after laminating the resin sheet 20 and the inner layer substrate 100, smoothing the laminated resin sheet 20 under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the mask film 300 side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for the lamination. The smoothing treatment may be performed using a commercially available laminator. Note that the lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0138] In a preferred example of a method for producing the intermediate laminate 10, a resin composition layer 210 is formed on the inner layer substrate 100 in step (I-1), followed by step (I-2) of curing the resin composition layer 210. By curing the resin composition layer 210 in step (I-2), an insulating layer 200 containing a cured product of the resin composition is formed, as shown in FIG. 1 . The curing conditions for the resin composition layer 210 are not particularly limited, and appropriate conditions can be adopted depending on the composition of the resin composition contained in the resin composition layer 210. For example, a resin composition layer 210 containing a thermosetting resin can be cured by thermal curing under appropriate conditions.

[0139] The curing conditions for the resin composition layer 210 may vary depending on the type of thermosetting material, such as a thermosetting resin. In one example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0140] Step (I-2) may include preheating the resin composition layer 210 at a temperature lower than the curing temperature before thermally curing the resin composition layer 210. For example, prior to thermally curing the resin composition layer 210, the resin composition layer 210 may be preheated at a temperature of typically 50° C. or higher and lower than 120° C. (preferably 60° C. or higher and 115° C. or lower, more preferably 70° C. or higher and 110° C. or lower) for typically 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes).

[0141] <Step (II): Formation of recess> Figure 3 is a schematic cross-sectional view illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. The method for manufacturing a wiring board according to the first embodiment includes, after step (I) of preparing an intermediate laminate 10, step (II) of forming recesses 400 in the mask film 300 of the intermediate laminate 10, as shown in Figure 3. As described above, the recesses 400 that are formed include portions where the thickness of the mask film 300 is relatively small and portions where there is no mask film 300.

[0142] The recess 400 is typically formed to have an opening 400K on the surface 300U of the mask film 300 opposite the inner substrate 100. Thus, the recess 400 is typically formed to be open to the outside through the opening 400K. Furthermore, the recess 400 thus formed is generally formed such that the surface 300U of the mask film 300 is recessed at the recess 400. Thus, the recess 400 may have a bottom surface 400B as the bottom portion close to the inner substrate 100, and a side surface 400S formed from the bottom surface 400B to the opening 400K.

[0143] In step (II), as illustrated in Fig. 3, recesses 400 may be formed so as to penetrate the mask film 300. When recesses 400 are formed so as to penetrate the mask film 300, the recesses 400 may be formed only in the mask film 300 and not in the insulating layer 200. In this case, the bottom surface 400B of the recesses 400 may be formed by the surface 200U of the insulating layer 200 opposite to the inner layer substrate 100.

[0144] 4 is a schematic cross-sectional view illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. When forming a recess 400 so as to penetrate the mask film 300, the recess 400 may be formed not only in the mask film 300 but also in the insulating layer 200, as illustrated in FIG. 4. In this case, the bottom surface 400B of the recess 400 may be formed in the insulating layer 200. Furthermore, of the side surface 400S of the recess 400, a portion 300S close to the opening 400K may be formed in the mask film 300, and a portion 200S close to the bottom surface 400B may be formed in the insulating layer 200.

[0145] 5 is a schematic cross-sectional view illustrating step (II) of the method for manufacturing a wiring board according to the first embodiment of the present invention. In step (II), as illustrated in FIG. 5, recess 400 may be formed so as not to penetrate mask film 300. In this case, bottom surface 400B of recess 400 may be formed within mask film 300.

[0146] As described above, the position of the bottom surface 400B of the recess 400 is not particularly limited and can be appropriately set so as to form the desired via hole and / or trench. Typically, from the viewpoint of significantly achieving the effects of the present invention, the recess 400 is formed so as not to penetrate the insulating layer 200. Therefore, the recess 400 is typically formed so that the inner substrate 100 is not exposed at the bottom surface 400B. Therefore, step (II) may include forming the recess 400 so that the inner substrate 100 is not exposed at the bottom of the recess 400 (the bottom surface 400B in the first embodiment).

[0147] In a preferred example, the specific position of the bottom surface 400B of the recess 400 in the thickness direction of the intermediate laminate 10 is as follows: That is, as shown in Fig. 5, the surface 200U of the insulating layer 200 opposite the inner substrate 100 is taken as the reference (0 μm), and a position closer to the inner substrate 100 is represented by a positive (+) sign, and a position farther from the inner substrate 100 is represented by a negative (-) sign. In this case, the position of the bottom surface 400B of the recess 400 relative to the surface 200U of the insulating layer 200 opposite the inner substrate 100 is preferably -5 μm or more, more preferably -4 μm or more, even more preferably -3 μm or more, and even more preferably -2 μm or more in the thickness direction, and is preferably +5 μm or less, more preferably +4 μm or less, even more preferably +3 μm or less, and even more preferably +2 μm or less.

[0148] In another preferred example, the specific position of the bottom surface 400B of the recess 400 in the thickness direction of the intermediate laminate 10 is as follows: That is, as shown in Fig. 5, the surface 200U of the insulating layer 200 opposite the inner substrate 100 is set as the reference (0 µm), and a position closer to the inner substrate 100 is represented by a positive (+) sign, and a position farther from the inner substrate 100 is represented by a negative (-) sign. In addition, the distance from the surface 200U of the insulating layer 200 opposite the inner substrate 100 to the bottom surface 400B of the recess 400 is represented as a relative value with respect to 100% of the thickness of the insulating layer 200 in step (I) (i.e., the thickness of the insulating layer 200 at the portion where the recess 400 is to be formed before the recess 400 is formed). In this case, the position of the bottom surface 400B of the recess 400 relative to the surface 200U of the insulating layer 200 opposite the inner layer substrate 100 is preferably -80% or more, more preferably -60% or more, even more preferably -40% or more in the thickness direction, and is preferably +80% or less, more preferably +60% or less, even more preferably +40% or less.

[0149] The dimension W of the opening 400K of the recess 400 formed in step (II) ４００Ｋ can be set according to the dimensions of the opening of the via hole and / or trench to be formed in the insulating layer 200. Here, the dimension W ４００ＫUnless otherwise specified, the dimension W of the opening 400K represents the minimum dimension of the opening 400K as viewed in the thickness direction. ４００Ｋ represents the diameter of the circular opening 400K. Also, for example, when the opening 400K is formed linearly as viewed in the thickness direction, the dimension W of the opening 400K is ４００Ｋ represents the width of the linear opening 400K. In one example, the dimension W ４００Ｋ The specific range of is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and may be 25 μm or less. ４００Ｋ may be the same or different.

[0150] There are no particular limitations on the method for forming the recesses 400. The recesses 400 can be formed, for example, by laser processing. In laser processing, the recesses 400 are usually formed by irradiating the mask film 300 side of the intermediate laminate 10 with laser light having a wavelength that can be absorbed by the mask film 300. Therefore, step (II) may include forming the recesses 400 in the mask film 300 by laser light.

[0151] The laser light source may be, for example, CO ２ Examples of such lasers include a laser (carbon dioxide laser), a UV-YAG laser, a UV laser, a YAG laser, and an excimer laser. Among these, a UV laser and an excimer laser are preferred because they can smoothly form small recesses 400. Preferred specific examples include a UV laser with a wavelength of 266 nm and an excimer laser with a wavelength of 248 nm.

[0152] The conditions for irradiating the laser beam are desirably set so as to form a recess 400 having an opening 400K of the desired dimensions. In one example, the number of shots is desirably set so as to form a recess 400 having a bottom 400B at a desired position. Generally, the greater the number of shots, the deeper the recess 400 can be formed. The number of laser beam shots is usually 1 to 100 shots, and from the viewpoint of increasing the processing speed and improving productivity, it is preferably in the range of 1 to 80 shots, and more preferably in the range of 1 to 60 shots. When the number of shots is 2 or more, the laser beam may be irradiated in either burst mode or cycle mode.

[0153] The energy of the laser light can be set depending on conditions such as the number of shots and the depth of the recess 400. From the viewpoint of smoothly forming the recess 400, the energy of the laser light per shot is set to preferably 0.1 μJ or more, more preferably 0.2 μJ or more, even more preferably 0.3 μJ or more, and particularly preferably 1 μJ or more. From the viewpoint of suppressing damage to the insulating layer 200 due to excessive energy, the upper limit of the energy of the laser light per shot is preferably 100 μJ or less, more preferably 50 μJ or less, and even more preferably 10 μJ or less.

[0154] When pulsed laser light is used as the laser light, the pulse width of the laser light is preferably 0.5 μsec or more, more preferably 0.7 μsec or more, even more preferably 1 μsec or more, and preferably 40 μsec or less, more preferably 35 μsec or less, and even more preferably 30 μsec or less. When the number of shots is two or more, the pulse widths may be the same or different. For example, after irradiating the barrier layer on the surface of the mask film 300 with laser light of a relatively high energy to remove the barrier layer, the thermoplastic resin layer 310 may be irradiated with laser light of a relatively low energy, so that the pulse width of the second and subsequent shots may be shorter than the pulse width of the first shot.

[0155] In the first embodiment, as shown in Figure 3, an example is shown in which laser light L is irradiated onto surface 300U of mask film 300 to form a recess 400 having a bottom surface 400B on surface 200U of insulating layer 200 opposite the inner layer substrate 100.

[0156] <Step (III): Plasma Treatment> Figure 6 is a schematic cross-sectional view illustrating step (III) of the method for manufacturing a wiring board according to the first embodiment of the present invention. The method for manufacturing a wiring board according to the first embodiment includes, after step (II) of forming recesses 400 in mask film 300 of intermediate laminate 10, step (III) of forming via holes 500 and / or trenches (not shown) in insulating layer 200 by plasma treatment, as shown in Figure 6. In the first embodiment, an example of forming via holes 500 in step (III) will be described.

[0157] Specifically, step (III) includes irradiating the mask film 300 of the intermediate laminate 10 with plasma, as indicated by arrow P. The plasma irradiation reduces the thickness of the mask film 300. At the same time, the insulating layer 200 is selectively removed from the portion below the recess 400, thereby forming one or both of the via hole 500 and the trench.

[0158] Specifically, when the recess 400 is formed so as to penetrate the mask film 300, plasma is irradiated onto the insulating layer 200 through the recess 400, thereby etching the insulating layer 200. When the recess 400 is formed so as not to penetrate the mask film 300, the mask film 300 is removed at the recess 400, and then the insulating layer 200 is irradiated with plasma through the recess 400, thereby etching the insulating layer 200. Etching progresses in the portion of the insulating layer 200 below the recess 400, but etching does not progress in other portions because they are protected by the mask film 300. Therefore, the insulating layer 200 is selectively removed below the recess 400, thereby forming the via hole 500 and / or trench. Specifically, the insulating layer 200 is removed to the extent that it penetrates the insulating layer 200 and exposes the surface 100U of the inner substrate 100, thereby forming the via hole 500. On the other hand, the insulating layer 200 is removed so as not to penetrate the insulating layer 200, thereby forming the trench. In the portions other than the recessed portions 400, the mask film 300 is thinned by etching.

[0159] The plasma treatment can be performed by treating the surface 200U of the insulating layer 200 and the surface 300U of the mask film 300 with plasma generated by introducing a gas into a plasma generator. Examples of plasma generation methods include microwave plasma, which generates plasma using microwaves; high-frequency plasma, which uses high-frequency waves; atmospheric pressure plasma, which is generated under atmospheric pressure; and atmospheric pressure plasma, which is generated under a vacuum. Atmospheric pressure plasma, which is generated under a vacuum, is preferred. Furthermore, the plasma used in step (III) is preferably RF plasma, which is excited by high-frequency waves.

[0160] The gas to be converted into plasma can be one that can form via holes 500 and / or trenches in the insulating layer 200. Such gases include O ２ Fluorine-based gases; Ar, N ２ Fluorine-based gases refer to gases containing fluorine atoms, for example, CF ４ , C ４ F ６ , C４ F ８ , C.H. ２ F ２ , CHF ３ Fluorocarbon gases such as SF ６ These gases may be used singly or in combination of two or more. ２ and SF ６ Preferably, the gas contains one or more selected from the group consisting of O ２ And, CF ４ , Ar and N ２ a mixed gas containing one or more selected from the group consisting of: ６ and Ar and O ２ and a mixed gas containing one or more selected from the group consisting of: ２ and CF ４ a mixed gas containing SF ６ , Ar and O ２ A mixed gas containing O is more preferred. ２ and CF ４ A gas mixture containing is particularly preferred.

[0161] When plasma is generated using a mixed gas containing two or more types of gases, it is preferable to adjust the mixing ratio of these gases to an appropriate range. ２ And, CF ４ , Ar and N ２ When using a mixed gas containing one or more gases selected from the group consisting of ４ , Ar and N ２ one or more gases selected from the group consisting of ２ The ratio of (a) to (b) is preferably 1 / 99 or more, more preferably 30 / 70 or more, even more preferably 70 / 30 or more, and is preferably 99 / 1 or less, more preferably 90 / 10 or less. ２ and CF ４ When a mixed gas containing these is used, it is preferable that the mixing ratio thereof is in the above range. Unless otherwise specified, "sccm" is a unit of gas flow rate, and the amount of gas flowing per minute is expressed as the volume (cm) of the gas when the gas is at 0°C and 1 atm. ３) is indicated.

[0162] The degree of vacuum in the processing environment during plasma processing is preferably 10 mTorr or more, more preferably 20 mTorr or more, and even more preferably 30 mTorr or more, and is preferably 2000 mTorr or less, more preferably 1000 mTorr or less, and even more preferably 500 mTorr or less.

[0163] The plasma exposure time in the plasma treatment can be set depending on the depth of the via hole 500 and / or trench to be formed. The plasma exposure time is set so that the mask film 300 remains on the insulating layer 200 after the plasma treatment. In one example, the specific treatment time is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more, and is preferably 120 minutes or less, more preferably 100 minutes or less, and more preferably 60 minutes or less.

[0164] The etching rate by the plasma treatment is preferably 100 nm / min or more, more preferably 110 nm / min or more, and even more preferably 120 nm / min or more. There is no particular upper limit, but it is preferably 2000 nm / min or less, more preferably 1500 nm / min or less, and even more preferably 1000 nm / min or less.

[0165] As described above, the insulating layer 200 is etched in the portion below the recess 400 by the plasma treatment in step (III). The etching amount of the insulating layer 200 in step (III) is preferably within a specific range. Here, the "etching amount of the insulating layer 200" refers to the amount of reduction in the thickness of the insulating layer 200 due to etching in the portion below the recess 400. The etching amount of the insulating layer 200 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more, relative to 100% of the thickness of the insulating layer 200 in the etched portion (i.e., the portion below the recess 400) in step (I). The upper limit is 100% or less. The etching amount of the insulating layer 200 is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. The upper limit is not particularly limited and may be, for example, 50 μm or less.

[0166] In step (III), the thickness of the mask film 300 is generally reduced by the plasma treatment. Therefore, the thickness of the mask film 300 immediately after the completion of step (III) is usually smaller than the thickness of the mask film 300 immediately before the start of step (III). From the viewpoint of smoothly peeling the mask film 300 in step (IV), the thickness of the mask film 300 immediately after the completion of step (III) is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. Furthermore, the thickness of the mask film 300 immediately after the completion of step (III) is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and usually less than 100%, of the thickness of the mask film 300 immediately before the start of step (III).

[0167] <Step (IV): Peeling off mask film 300> The method for manufacturing a wiring board according to the first embodiment includes step (IV) of peeling off mask film 300 after step (III) of forming either or both of via holes 500 and trenches (not shown). Figure 7 is a cross-sectional view schematically showing wiring board 30 obtained by the method for manufacturing a wiring board according to the first embodiment of the present invention. By peeling off mask film 300, as shown in Figure 7, wiring board 30 is obtained which includes inner substrate 100 and insulating layer 200 in which either or both of via holes 500 and trenches have been formed.

[0168] The masking film 300 may be peeled off manually or mechanically using an automatic peeling device. Typically, the masking film 300 is peeled off by pulling it relative to the circuit board 100 and the insulating layer 200. Examples of peeling methods include a method in which the circuit board 100 and the insulating layer 200 are transported with the masking film 300 fixed, and the masking film 300 is peeled off; a method in which the circuit board 100 and the insulating layer 200 are fixed, and the masking film 300 is pulled to peel off the masking film 300; a method in which the circuit board 100 and the insulating layer 200 are transported while the masking film 300 is pulled, and the masking film 300 is peeled off; etc.

[0169] When peeling the mask film 300, the angle that the peeling direction of the mask film 300 makes with respect to the surface of the insulating layer 200 is not particularly limited, but is preferably 70° or less, more preferably 50° or less, even more preferably 30° or less, and is usually 0° or more. The peeling speed of the mask film 300 is preferably 1 m / min to 20 m / min, more preferably 3 m / min to 10 m / min. The temperature conditions for peeling the mask film 300 are not particularly limited, but it is preferable to perform the peeling at room temperature (preferably 10°C to 40°C).

[0170] The via hole 500 and / or trench formed in the insulating layer 200 of the resulting wiring board 30 can have a large taper angle θ. Here, the taper angle θ represents the angle between the side surface 500S of the via hole 500 and the trench and the plane of the insulating layer 200, as described above. Since the bottom surface 500B of the via hole 500 and the trench is typically parallel to the plane of the insulating layer 200, the taper angle θ is represented by the angle between the side surface 500S and the plane including the bottom surface 500B. The range of this taper angle θ is preferably 65° or more, more preferably 70° or more, and even more preferably 75° or more. The upper limit is typically 90° or less, and may be 88° or less, 85° or less, etc.

[0171] In the above-described manufacturing method, the dimension W of the via hole 500 and / or the trench opening 500K formed in the insulating layer 200 is ５００Ｋ is usually determined by the dimension W of the opening 400K of the recess 400 formed in the mask film 300. ４００Ｋ Therefore, the dimension W of the via hole 500 and / or the trench opening 500K can be set to be equal to or smaller than ５００Ｋ Here, the dimension W of the via hole 500 and / or the trench opening 500K can be reduced. ５００Ｋ Unless otherwise specified, the dimension W of the opening 500K represents the minimum dimension of the opening 500K as viewed in the thickness direction. ５００Ｋ represents the diameter of the circular opening 500K. In addition, for example, when the opening 500K is formed linearly as viewed in the thickness direction, the dimension W of the opening 500K is ５００Ｋrepresents the width of the linear opening 500K.

[0172] Dimension W of the opening 400K of the recess 400 ４００Ｋ , the dimension W of the opening 500K of the via hole 500 and / or trench formed in the insulating layer 200 in the portion below the recess 400 ５００Ｋ The ratio of the opening size (W ５００Ｋ / W ４００Ｋ The range of this opening size ratio is, for example, usually 1.0 or less, preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.85 or less. There is no lower limit, but it is usually greater than 0.0, and can be, for example, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, etc.

[0173] The dimensions W of the specific via hole 500 and / or trench opening 500K are ５００Ｋ can be set depending on the design of the wiring board 30, and the dimension W ５００Ｋ In order to utilize the advantage of this embodiment that the dimension W of the opening 500K can be reduced, it is preferable that the dimension W of the opening 500K is small. ５００Ｋ The specific range is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, particularly preferably 20 μm or less.

[0174] Typically, the dimension W of the bottom surface 500B of the via hole 500 and / or trench formed in the insulating layer 200 is ５００Ｂ Here, the dimension W of the bottom surface 500B of the via hole 500 and / or the trench can be reduced. ５００Ｂ Unless otherwise specified, the dimension W of the bottom surface 500B represents the minimum dimension of the bottom surface 500B as viewed in the thickness direction. ５００Ｂ represents the diameter of the circular bottom surface 500B. In addition, for example, when the bottom surface 500B is formed linearly as viewed in the thickness direction, the dimension W of the bottom surface 500B is ５００Ｂ represents the width of the linear bottom surface 500B. Generally, the dimension W of the bottom surface 500B of the via hole 500 and / or trench ５００Ｂis the dimension W of the via hole 500 and / or trench opening 500K. ５００Ｋ The dimension W of the opening 500K is less than or equal to ５００Ｋ It may be smaller.

[0175] The dimensions W of the bottom surface 500B of the specific via hole 500 and / or trench ５００Ｂ The range is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less.

[0176] <Optional Step> The method for manufacturing wiring board 30 according to the first embodiment may further include an optional step in combination with the above-described steps (I) to (IV). For example, the method for manufacturing wiring board 30 according to the first embodiment may include step (V) of forming a conductor layer (not shown) on insulating layer 200. The conductor layer formed in step (V) may be referred to as a "circuit conductor layer" hereinafter. Step (V) is usually performed after step (IV).

[0177] Generally, in step (V), a circuit conductor layer is formed on the surface 200U of the insulating layer 200 opposite the inner layer substrate 100. The circuit conductor layer may also be formed in the via holes 500 and / or trenches.

[0178] The circuit conductor layer includes a conductive material, preferably only a conductive material. The conductive material is not particularly limited. Preferably, the circuit conductor layer includes one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The circuit conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among these, from the viewpoints of versatility in forming the circuit conductor layer, cost, and ease of patterning, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy is preferred. A single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

[0179] The circuit conductor layer may have a single layer structure, or a multi-layer structure including two or more single metal layers or alloy layers containing different types of metals or alloys. When the circuit conductor layer has a multi-layer structure, the layer in contact with the insulating layer 200 is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0180] There are no limitations on the method for forming the circuit conductor layer. Examples of methods for forming the circuit conductor layer include plating, sputtering, vapor deposition, and combinations thereof. Among these, from the viewpoint of manufacturing a wiring board by a dry process, sputtering and vapor deposition are preferred, and sputtering is more preferred. Furthermore, from the viewpoint of smooth formation of the circuit conductor layer, it is preferred to form the circuit conductor layer by a plating method. In a preferred example, plating is performed on the insulating layer 200 by an appropriate method such as a semi-additive method or a full-additive method to form a circuit conductor layer having a desired pattern shape.

[0181] The thickness of the circuit conductor layer depends on the design of the desired wiring board 30, but from the viewpoint of thinning, it is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and preferably 35 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, even more preferably 10 μm or less.

[0182] From the viewpoint of utilizing the advantage of this embodiment that the dimensions of the openings of the via hole 500 and trench can be reduced, when the circuit conductor layer forms circuit wiring, the lines of the circuit conductor layer are preferably small. The specific range of the lines of the circuit conductor layer is preferably 5 μm or less, more preferably 4 μm, and even more preferably 3 μm. The lower limit of the line is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

[0183] From the viewpoint of utilizing the advantage of this embodiment that the dimensions of the openings of the via hole 500 and the trench can be reduced, when the circuit conductor layer forms circuit wiring, the spacing between the circuit conductor layers is preferably small. The specific range of the spacing between the circuit conductor layers is preferably 5 μm or less, more preferably 4 μm, and even more preferably 3 μm. The lower limit of the spacing is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

[0184] In order to utilize the advantage of this embodiment that the dimensions of the via hole 500 and trench openings can be reduced, when the circuit conductor layer forms circuit wiring, the minimum line / space ratio of the circuit conductor layer is preferably 5 μm / 5 μm or less, more preferably 4 μm / 4 μm or less, even more preferably 3 μm / 3 μm or less, and preferably 0.1 μm / 0.1 μm or more, more preferably 0.5 μm / 0.5 μm or more, and even more preferably 1 μm / 1 μm or more. Furthermore, the wiring pitch of the circuit conductor layer is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 6 μm or less, and preferably 0.2 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. The line / space ratio and pitch may each be uniform or non-uniform throughout the circuit conductor layer.

[0185] <Repetition of Steps> In the method for manufacturing the wiring board 30 according to the first embodiment, each of steps (I), (II), (III), and (IV) may be performed once or twice or more times. Therefore, the method for manufacturing the wiring board 30 according to the first embodiment may include performing steps (I), (II), (III), and (IV) in this order twice or more times. Furthermore, the method for manufacturing the wiring board 30 according to the first embodiment may include performing any step twice or more times, such as performing steps (I), (II), (III), (IV), and (V) twice or more times in this order. Specifically, a wiring board manufactured by performing steps (I), (II), (III), (IV), and (V) a first time may be used as an inner layer substrate, and steps (I), (II), (III), (III), (IV), and (V) a second time may be performed. These methods allow for the manufacture of a wiring board having a multilayer structure (multilayer wiring board). For example, a multilayer wiring board having two or more or three or more conductor layers may be manufactured.

[0186] <Method for Manufacturing a Wiring Board According to a Second Embodiment> In the first embodiment described above, an example was shown in which the recesses 400 are formed in the mask film 300 by laser processing, but the recesses 400 may be formed by a method other than laser processing. Another preferred example of a method for forming the recesses 400 is an imprinting method. Below, a method for manufacturing a wiring board according to a second embodiment of the present invention using this imprinting method will be described. In the second embodiment, parts that are the same as those in the first embodiment will be described using the same reference numerals as those in the first embodiment.

[0187] The method for manufacturing a wiring board according to the second embodiment is the same as the method for manufacturing a wiring board according to the first embodiment, except that an imprinting method is used to form recesses in the mask film in step (II). Furthermore, step (II) using the imprinting method includes pressing the mask film with a mold, as described below.

[0188] 8, 9, and 10 are schematic cross-sectional views illustrating step (II) of the method for manufacturing a wiring board according to a second embodiment of the present invention. In the method for manufacturing a wiring board according to the second embodiment, step (II) is performed after step (I) of preparing an intermediate laminate 10, as in the first embodiment. In step (II), as shown in FIG. 8, a mold 600 having a convex portion 610 corresponding to the concave portion 400 to be formed (see FIG. 10) is prepared. Then, as shown in FIG. 9, the mask film 300 is pressed by the mold 600 so that the convex portion 610 abuts against the mask film 300. When the mask film 300 is pressed by the mold 600, a concave portion 400 corresponding to the convex portion 610 is formed in the mask film 300. Therefore, when the mold 600 is removed after pressing, a mask film 300 having a concave portion 400 is obtained, as shown in FIG. 10. The concave portion 400 formed in the second embodiment may be the same as the concave portion 400 formed in the first embodiment.

[0189] There are no particular limitations on the material of the mold 600 as long as it can form the recess 400. Examples of materials for the mold 600 include metal and silicon.

[0190] The pressing temperature by the mold 600 is not particularly limited as long as it can form the recess 400. In one example, the pressing temperature is preferably 100°C or higher, more preferably 120°C or higher, even more preferably 140°C or higher, and is preferably 350°C or lower, more preferably 320°C or lower, even more preferably 300°C or lower.

[0191] The pressing pressure applied by the mold 600 is not particularly limited as long as it can form the recess 400. In one example, the pressing pressure is preferably 1 MPa or more, more preferably 3 MPa or more, even more preferably 10 MPa or more, and is preferably 100 MPa or less, more preferably 70 MPa or less, even more preferably 50 MPa or less.

[0192] 11 is a schematic cross-sectional view illustrating step (III) of the method for manufacturing a wiring board according to a second embodiment of the present invention. The method for manufacturing a wiring board according to the second embodiment includes, after step (II), step (III) of forming one or both of a via hole 500 and a trench (not shown) in the insulating layer 200 by plasma treatment, as shown in FIG. 11 . Like step (III) according to the first embodiment, step (III) according to the second embodiment includes irradiating the mask film 300 of the intermediate laminate 10 with plasma. The plasma treatment reduces the thickness of the mask film 300, and simultaneously selectively removes the insulating layer 200 in the portion below the recess 400, thereby forming one or both of the via hole 500 and the trench.

[0193] 12 is a cross-sectional view schematically illustrating a wiring board 40 obtained by a wiring board manufacturing method according to a second embodiment of the present invention. The wiring board manufacturing method according to the second embodiment includes a step (IV) of peeling off the mask film 300 after step (III). The peeling off of the mask film 300 according to the second embodiment can be performed in the same manner as the peeling off of the mask film 300 according to the first embodiment. By peeling off the mask film 300, a wiring board 40 is obtained, as shown in FIG. 12, which includes an inner substrate 100 and an insulating layer 200 in which either or both of a via hole 500 and a trench are formed.

[0194] The manufacturing method for wiring board 40 according to the second embodiment can achieve the same advantages as the manufacturing method for wiring board 30 according to the first embodiment. Furthermore, compared to laser processing, imprinting makes it easier to improve the cross-sectional shape of recesses 400 formed in mask film 300. Specifically, imprinting makes it easy to make the taper angle of recesses 400 approach 90°. Here, the "taper angle of recesses 400" refers to the angle that side surface 400S of recesses 400 forms with respect to the layer plane of mask film 300. Therefore, the manufacturing method according to the second embodiment makes it easy to increase the taper angle θ of via holes 500 and / or trenches formed in insulating layer 200.

[0195] The production method according to the second embodiment may include any optional step, as in the production method according to the first embodiment. Furthermore, in the production method according to the second embodiment, steps (I) to (IV) and any optional step may be performed only once or may be performed twice or more times, as in the production method according to the first embodiment.

[0196] <Method for Manufacturing a Wiring Board According to a Third Embodiment> In the first and second embodiments described above, an example in which one recess 400 is formed in the mask film 300 in step (II) has been described. However, two or more recesses may be formed. Furthermore, when two or more recesses are formed, the shapes and dimensions of the recesses may be the same or different. For example, a first recess for forming a via hole and a second recess for forming a trench may be formed in combination in the mask film.

[0197] Hereinafter, a method for manufacturing a wiring board according to a third embodiment of the present invention will be described, which includes step (II) of forming the first recess and the second recess in combination. Since trenches, which may have complex pattern shapes, are generally formed efficiently by imprinting, the third embodiment will be described by showing an example in which the imprinting method is employed in step (II), as in the second embodiment. Furthermore, in the third embodiment, the same parts as in the first and second embodiments will be described by using the same reference numerals as in the first and second embodiments.

[0198] The method for manufacturing a wiring board according to the third embodiment is the same as the method for manufacturing a wiring board according to the second embodiment, except that in step (II), a first recess for forming a via hole and a second recess for forming a trench are combined and formed in the mask film.

[0199] 13, 14, and 15 are schematic cross-sectional views illustrating step (II) of the method for manufacturing a wiring board according to the third embodiment of the present invention. In the method for manufacturing a wiring board according to the third embodiment, step (II) is performed after step (I) of preparing an intermediate laminate 10, as in the first and second embodiments. In step (II), as shown in FIG. 13, a mold 700 is prepared having first convex portions 710 shaped to correspond to the first concave portions 410 (see FIG. 15) and second convex portions 720 shaped to correspond to the second concave portions 420 (see FIG. 15). Then, as shown in FIG. 14, the mask film 300 is pressed by the mold 700 so that the first convex portions 710 and the second convex portions 720 abut against the mask film 300. When the mask film 300 is pressed by the mold 700, first concave portions 410 shaped to correspond to the first convex portions 710 and second concave portions 420 shaped to correspond to the second convex portions 720 are formed in the mask film 300. Therefore, when the mold 700 is removed after pressing, a mask film 300 having a first recess 410 and a second recess 420 is obtained, as shown in FIG. 15. In general, the first recess 410 corresponding to a via hole is formed deeper than the second recess 420 corresponding to a trench. The position of the bottom surface 410B of the first recess 410 and the position of the bottom surface 420B of the second recess 420 may be set within the range of the position of the bottom surface 400B of the recess 400 described in the first embodiment. In addition, the dimension W of the opening 410K of the first recess 410 ４１０Ｋ , and the dimension W of the opening 420K of the second recess 420 ４２０Ｋ is the dimension W of the opening 400K of the recess 400 described in the first embodiment. ４００Ｋ It may be set in the range.

[0200] 16 is a schematic cross-sectional view illustrating step (III) of the method for manufacturing a wiring board according to a third embodiment of the present invention. The method for manufacturing a wiring board according to the third embodiment includes, after step (II), step (III) of forming a via hole 510 and a trench 520 in the insulating layer 200 by plasma treatment, as shown in FIG. 16 . Like step (III) according to the first and second embodiments, step (III) according to the third embodiment includes irradiating the mask film 300 of the intermediate laminate 10 with plasma. The plasma treatment reduces the thickness of the mask film 300. At the same time, the insulating layer 200 is selectively removed from the portion below the first recess 410 to form the via hole 510, and the insulating layer 200 is selectively removed from the portion below the second recess 420 to form the trench 520.

[0201] 17 is a cross-sectional view schematically illustrating a wiring board 50 obtained by a wiring board manufacturing method according to a third embodiment of the present invention. The wiring board manufacturing method according to the third embodiment includes a step (IV) of peeling off the mask film 300 after step (III). The mask film 300 according to the third embodiment can be peeled off in the same manner as the mask film 300 according to the first and second embodiments. By peeling off the mask film 300, a wiring board 50 is obtained, as shown in FIG. 17, which includes an inner substrate 100 and an insulating layer 200 having via holes 510 and trenches 520 formed therein.

[0202] The method for manufacturing wiring board 50 according to the third embodiment can provide the same advantages as those of the method for manufacturing wiring board 30 according to the first embodiment and the method for manufacturing wiring board 40 according to the second embodiment.

[0203] The production method according to the third embodiment may include an optional step, similar to the production methods according to the first and second embodiments. Furthermore, in the production method according to the third embodiment, steps (I) to (IV) and any optional step may be performed only once, or may be performed twice or more times, similar to the production methods according to the first and second embodiments.

[0204] <Applications of Wiring Boards> The wiring boards manufactured by the above-described manufacturing method include an inner layer substrate and an insulating layer. Furthermore, wiring boards typically include conductor layers such as inner layer conductor layers and circuit conductor layers, and these conductor layers can form circuit wiring. Examples of such wiring boards include printed wiring boards, interposers, and package substrates. Examples of packages to which package substrates can be applied include fan-in packages and fan-out packages.

[0205] There is no particular limitation on the area of ​​the wiring board. In one example, the area of ​​the wiring board is preferably 2500 mm ２ More preferably, 3000 mm ２ More preferably, 3500 mm ２ or more, preferably 10,000 mm ２ The following is the result.

[0206] <Semiconductor Device> A semiconductor device can be manufactured using the above-described wiring board. This semiconductor device includes a wiring board. Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.).

[0207] The semiconductor device may have a fan-out structure or a chiplet structure. The semiconductor device may also have a semiconductor chip on a wiring board. In this case, the semiconductor chip is preferably a mixed system of a logic die and a memory die.

[0208] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, unless otherwise specified, the operations described below were carried out in an atmospheric environment at room temperature and normal pressure (25°C, 1 atm).

[0209] Example 1 (1-1. Production of Thermosetting Resin Composition) A mixture of 6 parts of bixylenol-type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight: approximately 185 g / eq.), 5 parts of naphthalene-type epoxy resin ("ESN475V" manufactured by Nippon Steel & Sumikin Chemical (now Nippon Steel Chemical & Material) Corporation, epoxy equivalent weight: approximately 332 g / eq.), 15 parts of bisphenol AF-type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight: approximately 238 g / eq.), and 15 parts of naphthylene ether-type epoxy resin ("HP6000L" manufactured by DIC Corporation). A resin solution was obtained by dissolving 2 parts of a cyclohexane-type epoxy resin ("ZX1658GS" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight: approximately 135 g / eq.), 2 parts of a cyclohexane-type epoxy resin ("YL7500BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of cyclohexanone:methyl ethyl ketone (MEK) with a solids content of 30 mass%, Mw=44,000) in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone with heating and stirring. After cooling this resin solution to room temperature, 4 parts of a triazine skeleton-containing cresol novolak-based curing agent ("LA-3018-50P" manufactured by DIC Corporation, hydroxyl group equivalent of approximately 151 g / eq., 2-methoxypropanol solution with a solid content of 50%), 12 parts of an active ester-based curing agent ("HP-B-8151-62T" manufactured by DIC Corporation, active group equivalent of 238 g / eq., toluene solution with a solid content of 62%), 4 parts of a solvent (solvent naphtha, "IP150" manufactured by Idemitsu Kosan Co., Ltd.), and an inorganic filler (silica particles, average particle size 0.50 μm, BET specific surface area 6 m) were added thereto. ２ 110 parts of a hydroxybenzoate (1 / g) and 0.05 parts of an amine curing accelerator (4-dimethylaminopyridine (DMAP)) were mixed and uniformly dispersed in a high-speed rotary mixer, and then filtered through a cartridge filter ("SHP050" manufactured by ROKITECHNO Co., Ltd.) to prepare a thermosetting resin composition.

[0210] (1-2. Production of Resin Sheet) A masking film was prepared, comprising a polyethylene naphthalate film ("Teonex Q83" manufactured by Toyobo Co., Ltd., thickness 25 μm) as a thermoplastic resin layer, and a release layer formed on one side of the polyethylene naphthalate film. A thermosetting resin composition was uniformly applied to the release layer of the masking film using a die coater so that the thickness of the resin composition layer after drying would be 5 μm, and the resin composition layer was formed by drying at 70°C to 95°C for 2 minutes. Next, a roughened surface of a polypropylene film ("Alphan MA-411" manufactured by Oji F-Tex Co., Ltd., thickness 15 μm) was laminated as a protective film on the side of the resin composition layer not bonded to the masking film, so as to be bonded to the resin composition layer. This yielded a resin sheet for forming an insulating layer, comprising a masking film, a resin composition layer, and a protective film in this order.

[0211] (1-3. Preparation of inner layer substrate) A silicon wafer (copper layer thickness: 1 μm, inner layer substrate thickness: 0.8 mm, 8-inch size) with a copper layer formed on one side was prepared as an inner layer substrate. This inner layer substrate was placed in an oven at 130° C. and dried for 30 minutes.

[0212] (1-4. Formation of insulating layer: step (I)) Lamination of resin sheet: The protective film was peeled off from the resin sheet. Using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.), a resin sheet was laminated on one side of the inner layer substrate so that the resin composition layer and the inner layer substrate were in contact. Lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at a temperature of 130°C and a pressure of 0.74 MPa for 45 seconds. Next, a heat press was performed at a temperature of 120°C and a pressure of 0.5 MPa for 75 seconds.

[0213] Curing of resin composition layer: The inner layer substrate laminated with the resin sheet was placed in an oven at 100°C and heated for 30 minutes, then transferred to an oven at 180°C and heated for 30 minutes. The heating thermally cured the resin composition layer to form an insulating layer. Thus, an intermediate laminate A was obtained, which included the inner layer substrate, the insulating layer (thickness 5 μm), and the mask film in this order.

[0214] (1-5. Mask formation: step (II)) Laser processing was performed on the mask film side surface of intermediate laminate A using a UV laser ("LU-2L212 / M50L" manufactured by Via Mechanics) to form a circular hole-shaped recess in the mask film, having a circular opening and a bottom surface when viewed from the thickness direction. In this laser processing, laser light was irradiated while adjusting the number of shots so that a recess of the desired depth was formed. Specifically, in Example 1, the number of shots was adjusted so that the bottom surface of the recess was formed at a position −1.5 μm from the surface of the insulating layer opposite the inner layer substrate (i.e., a position 1.5 μm away from the surface of the insulating layer on the opposite side to the inner layer substrate).

[0215] (1-6. Plasma Etching: Step (III)) Plasma treatment was carried out using a plasma dry etching apparatus ("PlasmaPro100" manufactured by Oxford Instruments) with a mask film as a plasma mask, and via holes penetrating the insulating layer were formed in the insulating layer. The via holes were formed in the shape of round holes with circular openings and bottoms when viewed from the thickness direction, and the copper layer of the inner layer substrate was exposed at the bottoms. The plasma treatment was carried out using CF as the gas. ４ and O ２ (CF ４ / O ２ The plasma treatment was carried out using a mixture of 80 / 20 (sccm) of 1,000 volts of ethylenediaminetetraacetic acid and 1,000 volts of ethylenediaminetetraacetic acid under the conditions of a vacuum level of 50 mTorr, RF power of 120 W, and ICP power of 100 W. The plasma treatment was carried out to such an extent that the mask film was not completely removed and remained on the insulating layer.

[0216] (1-7. Peeling off the support: step (IV)) After forming the via holes in the insulating layer, the mask film remaining on the insulating layer was pulled and peeled off to obtain an evaluation substrate corresponding to a wiring board having an inner layer substrate and an insulating layer.

[0217] (1-8. Observation of Evaluation Substrate) The evaluation substrate was subjected to cross-sectional observation using an FIB-SEM (Hitachi High-Technologies Corporation's "Ethos NX5000"), and the via holes formed in the insulating layer were observed to measure the top diameter, bottom diameter, and taper angle of the via holes. Here, the top diameter of the via hole refers to the diameter of the opening of the via hole, and the bottom diameter of the via hole refers to the diameter of the bottom surface of the via hole. The taper angle was evaluated according to the following criteria: "Excellent": Taper angle > 65°; "Poor": Taper angle ≦ 65°

[0218] Example 2 An evaluation board was manufactured and evaluated in the same manner as in Example 1, except that in step (1-5), the number of shots for laser processing was adjusted so that the bottom surface of the recess was formed at a position of 0 μm from the surface of the insulating layer on the opposite side of the inner layer substrate (i.e., the position of the surface of the insulating layer).

[0219] Example 3 An evaluation board was manufactured and evaluated in the same manner as in Example 1, except that in step (1-5), the number of laser processing shots was adjusted so that the bottom surface of the recess was formed at a position +1.0 μm from the surface of the insulating layer opposite the inner layer substrate (i.e., a position 1.0 μm away from the surface of the insulating layer toward the inner layer substrate).

[0220] Example 4 In step (1-2), the mask film was changed to a film comprising a polyimide film (Ube Industries, Ltd., "Upilex-S," thickness 13 μm) as a thermoplastic resin layer and a release layer formed on one side of the polyimide film. In step (1-5), the number of laser processing shots was adjusted so that the bottom of the recess was formed at a position −0.5 μm from the surface of the insulating layer on the side opposite the inner layer substrate (i.e., a position 0.5 μm away from the surface of the insulating layer on the side opposite the inner layer substrate). Except for the above, the evaluation board was manufactured and evaluated using the same method as in Example 1.

[0221] Comparative Example 1 Steps (1-1) to (1-4) were performed using the same method as in Example 1 to obtain an intermediate laminate A including an inner layer substrate, an insulating layer (5 μm thick), and a mask film in this order. The mask film was peeled off from the intermediate laminate A. Laser processing was performed using a UV laser ("LU-2L212 / M50L" manufactured by Via Mechanics) on the surface of the insulating layer exposed by peeling off the mask film, to form via holes in the insulating layer. Specifically, in this laser processing, laser light was irradiated while adjusting the number of shots so that the copper layer of the inner layer substrate was exposed at the bottom of the via hole. This laser processing resulted in an evaluation substrate including an inner layer substrate and an insulating layer with a via hole formed therein. The evaluation substrate thus obtained was evaluated using the same method as in Step (1-8) of Example 1.

[0222] Comparative Example 2 Steps (1-1) to (1-4) were performed using the same method as in Example 1 to obtain an intermediate laminate A including an inner layer substrate, an insulating layer (5 μm thick), and a mask film in this order. Laser processing was performed on the mask film side of intermediate laminate A using a UV laser ("LU-2L212 / M50L" manufactured by Via Mechanics) to form via holes penetrating the mask film and insulating layer. Specifically, in this laser processing, laser light was irradiated while adjusting the number of shots so that the copper layer of the inner layer substrate was exposed at the bottom of the via hole. The mask film was then peeled off to obtain an evaluation substrate including an inner layer substrate and an insulating layer with a via hole formed therein. The evaluation substrate thus obtained was evaluated using the same method as in Step (1-8) of Example 1.

[0223] <Results> The results of the Examples and Comparative Examples are shown in the table below. In the table below, the meanings of the abbreviations are as follows: PEN: polyethylene naphthalate PI: polyimide Top diameter of recess: diameter of the opening of the recess formed in the mask film Top diameter of via hole: diameter of the opening of the via hole formed in the insulating layer Bottom diameter of via hole: diameter of the bottom of the via hole formed in the insulating layer

[0224]

[0225] <Measurement of Dielectric Properties of Cured Resin Composition> The protective film was peeled off from the resin sheet produced in Example 1, and the resin composition layer was cured by heating at 200°C for 90 minutes to obtain an insulating layer. After peeling off the mask film, the relative dielectric constant and dielectric loss tangent of the insulating layer were measured. The measurement was performed by a cavity resonance perturbation method using a measuring device ("HP8362B" manufactured by Agilent Technologies) at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. As a result of the measurement, the relative dielectric constant of the insulating layer was 3.4, and the dielectric loss tangent was 0.0054.

[0226] REFERENCE SIGNS LIST 10 Laminate (intermediate laminate) 20 Resin sheet 30 Wiring board 40 Wiring board 50 Wiring board 100 Substrate (inner layer substrate) 100U Surface of inner layer substrate 110 Support substrate 120 Conductor layer (inner layer conductor layer) 200 Insulating layer 200U Surface of insulating layer 210 Resin composition layer 300 Thermoplastic film (mask film) 300U Surface of mask film 310 Thermoplastic resin layer 400 Recess 400K Opening of recess 400B Bottom surface of recess 400S Side surface of recess 410 First recess 420 Second recess 500 Via hole 500K Opening of via hole 500B Bottom surface of via hole 500S Side surface of via hole 510 Via hole 520 Trench 600 Mold 610 Convex portion 700 Mold 710 First convex portion 720 Second convex portion

Claims

1. A method for manufacturing a wiring board, comprising the steps of: (I) preparing a laminate having, in this order, a substrate, an insulating layer, and a thermoplastic film; (II) forming a recess in the thermoplastic film; (III) forming a via hole and / or a trench in the insulating layer by plasma treatment; and (IV) peeling off the thermoplastic film.

2. The method for producing a wiring board according to claim 1, wherein step (I) comprises: step (I-1) of forming a resin composition layer containing a resin composition on a substrate; and step (I-2) of curing the resin composition layer.

3. The method for producing a wiring board according to claim 2, wherein step (I-1) comprises laminating a resin sheet including a thermoplastic film and a resin composition layer on a substrate so that the resin composition layer is bonded to the substrate.

4. The method for producing a wiring board according to claim 1, wherein step (II) includes forming recesses in the thermoplastic film by means of laser light.

5. The method for producing a wiring board according to claim 1, wherein step (II) includes pressing the thermoplastic film with a mold.

6. The method for producing a wiring board according to claim 1, wherein step (II) includes forming a recess so that the substrate is not exposed at the bottom of the recess.

7. The method for producing a wiring board according to claim 1, wherein step (III) includes irradiating the thermoplastic film with plasma to reduce the thickness of the thermoplastic film and at the same time remove the insulating layer in the portion below the recess to form one or both of a via hole and a trench.

8. The method for producing a wiring board according to claim 1, wherein the amount of the insulating layer etched in step (III) is 30% or more relative to 100% of the thickness of the insulating layer in step (I).

9. The method for producing a wiring board according to claim 1, further comprising the step (V) of forming a conductor layer on the insulating layer.

10. A method for producing a wiring board according to claim 1, comprising carrying out steps (I), (II), (III) and (IV) in this order at least twice.

11. The method for producing a wiring board according to claim 1, wherein the thermoplastic film is provided with a release layer.

12. The method for producing a wiring board according to claim 2, wherein the resin composition contains a thermosetting resin.

13. The method for producing a wiring board according to claim 2, wherein the resin composition contains an inorganic filler.

Images