Printed wiring board manufacturing method

Abstract

To provide a method for manufacturing a printed wiring board or the like capable of improving conduction reliability by suppressing the occurrence of voids and gaps, between metal via pads and plating in via holes.SOLUTION: A method for manufacturing a printed wiring board includes, in this order, (A) a step of laminating a resin composition layer containing a resin composition and a metal foil in this order on a substrate having a metal via pad formed thereon, (B) a step of curing the resin composition layer to form an insulating layer, (C) a step of forming a via hole on the metal via pad, (D) a step of removing the metal foil, and (E) a step of forming a conductor layer. E1 / E2≥1.5 is satisfied, where E1 (μm / min) is an etching rate when the metal foil is immersed in etchant at 25°C for 2 minutes, and E2 (μm / min) is an etching rate when a metal species of the metal via pad is immersed in the etchant at 25°C for 2 minutes.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a printed wiring board and a resin sheet with a metal foil. [Background technology]

[0002] In recent years, electronic devices have become smaller and more powerful, and there is a demand for finer wiring and smaller diameter via holes in printed wiring boards. To this end, methods have been studied, such as a method of electroless plating on a smooth surface as disclosed in Patent Document 1, and a method of using a metal foil such as a copper foil and transferring the surface irregularities formed on the metal foil to a resin composition layer as disclosed in Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-031583 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-221870 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] In a method of using a metal foil to transfer the surface irregularities formed on the metal foil to a resin composition layer, after the surface irregularities of the metal foil are transferred to the resin composition layer, via holes are typically formed on the metal foil and the insulating layer, and the metal foil is removed by etching.

[0005] However, when the metal foil is removed by etching, the metal via pad at the bottom of the via hole is also etched. Therefore, when a plated conductor layer is formed on the insulating layer and in the via hole after etching, either a void (not shown) or an interface 41 may occur between the metal via pad 12 and the plating 30 in the via hole 13, as shown in FIG. 7 . The presence of a void may reduce electrical continuity reliability, and the occurrence of an interface may cause the plating to peel off, resulting in reduced electrical continuity reliability. Furthermore, as shown in FIG. 8 , if a recess 12a occurs in the metal via pad 12 due to etching, a gap may form between the metal via pad 12 and the plating 40 in the via hole 13, resulting in reduced electrical continuity reliability. This deterioration in electrical continuity reliability is particularly pronounced when the via pad diameter is small.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing a printed wiring board that can suppress the occurrence of voids and gaps between a via pad and the plating in a via hole, thereby improving conductivity reliability; and a resin sheet with a metal foil used in the manufacturing method. [Means for solving the problem]

[0007] As a result of intensive research into the above problem, the inventors discovered that the above problem can be solved when the etching rate of the metal foil and the etching rate of the metal via pad of the substrate satisfy a certain relationship, and thus completed the present invention.

[0008] That is, the present invention includes the following. [1] (A) a step of laminating a resin composition layer containing a resin composition and a metal foil in this order on a substrate on which a metal via pad has been formed; (B) a step of curing the resin composition layer to form an insulating layer; (C) forming a via hole; (D) removing the metal foil; and (E) forming a conductor layer, A method for manufacturing a printed wiring board, in which E1 / E2≧1.5 is satisfied, where E1 (μm / min) is the etching rate when a metal foil is immersed in an etching solution at 25°C for 2 minutes, and E2 (μm / min) is the etching rate when a metal species of a metal via pad is immersed in the same etching solution at 25°C for 2 minutes. [2] The method for producing a printed wiring board according to [1], wherein step (A) uses a support and a resin sheet with metal foil, which has a metal foil and a resin composition layer formed on the support in this order, and laminates the resin sheet with metal foil on a substrate on which a metal via pad has been formed so that the resin composition layer is bonded to the substrate. [3] The method for producing a printed wiring board according to [1], wherein step (A) comprises laminating a metal foil sheet, in which a metal foil is formed on a support, onto a substrate on which metal via pads are formed, so that the metal foil is bonded to the substrate via a resin composition layer. [4] The method for producing a printed wiring board according to [2] or [3], which comprises a step of removing the support after step (B) and before step (C). [5] The method for producing a printed wiring board according to any one of [1] to [4], wherein the diameter of the metal via pad is 30 μm or more. [6] The method for producing a printed wiring board according to any one of [1] to [5], wherein the opening diameter of the via hole is 5 μm or more. [7] The method for producing a printed wiring board according to any one of [1] to [6], wherein the resin composition layer has a thickness of 2 μm or more and 50 μm or less. [8] The method for producing a printed wiring board according to any one of [1] to [7], wherein the resin composition contains a curable resin. [9] The method for producing a printed wiring board according to any one of [1] to [8], wherein the metal foil comprises a foil made of an alloy of copper and one or more metals selected from nickel, titanium, and cobalt.

[10] The method for producing a printed wiring board according to any one of [1] to [9], wherein the metal via pad contains copper.

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

[10] , wherein the etching solution is at least one selected from the group consisting of an etching solution containing any one of hydrogen peroxide, sulfuric acid, and nitric acid; an etching solution containing a fluoride; an etching solution containing hydrogen peroxide and aqueous ammonia; and an etching solution containing any one of copper sulfate, iron sulfate, and copper chloride.

[12] A resin sheet with a metal foil comprising a support and a resin composition layer provided on the support, the resin composition layer comprising a metal foil and a resin composition, A resin sheet with metal foil that satisfies E1 / E2≧1.5 when the resin sheet with metal foil is laminated in the order of a resin composition layer and a metal foil on a substrate on which a metal via pad is formed, the etching rate when the metal foil is immersed in an etching solution at 25°C for 2 minutes is defined as E1 (μm / min), and the etching rate when the metal species of the metal via pad is immersed in the etching solution at 25°C for 2 minutes is defined as E2 (μm / min). [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for manufacturing a printed wiring board that can suppress the occurrence of voids and gaps between the via pad and the plating in the via hole and improve the conductivity reliability; and a resin sheet with metal foil used in the manufacturing method. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a substrate as an example of a method for manufacturing a printed wiring board. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a state in which a resin sheet with a metal foil is bonded to a substrate as an example of a method for manufacturing a printed wiring board. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the state of the substrate after forming an insulating layer as an example of a method for manufacturing a printed wiring board. [Figure 4] FIG. 4 is a schematic cross-sectional view of a substrate in which via holes are formed as an example of a method for manufacturing a printed wiring board. [Figure 5]FIG. 5 is a schematic cross-sectional view of the substrate after removing the metal foil as an example of a method for producing a printed wiring board. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a state of a substrate on which a conductor layer is formed as an example of a method for manufacturing a printed wiring board. [Figure 7] FIG. 7 is a schematic cross-sectional view showing the state in which an interface is generated between a metal via pad and plating in a via hole. [Figure 8] FIG. 8 is a schematic cross-sectional view showing a state in which a gap occurs between a metal via pad and the plating inside a via hole. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the state of the amount of depression. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below with reference to preferred embodiments thereof. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0012] [Printed wiring board manufacturing method] The method for producing a printed wiring board of the present invention comprises: (A) a step of laminating a resin composition layer containing a resin composition and a metal foil in this order on a substrate on which a metal via pad has been formed; (B) a step of curing the resin composition layer to form an insulating layer; (C) forming a via hole; (D) removing the metal foil; and (E) forming a conductor layer, When the etching rate of the metal foil when immersed in an etching solution at 25°C for 2 minutes is E1 (μm / min), and the etching rate of the metal species of the metal via pad when immersed in the same etching solution at 25°C for 2 minutes is E2 (μm / min), the relationship E1 / E2≧1.5 is satisfied.

[0013] The metal foil is used to transfer its surface irregularities to the insulating layer. After drilling the metal foil and insulating layer to form via holes, a desmear process is typically performed to remove smears (residues) in the via holes. The metal foil is also used to prevent the insulating layer surface from being roughened by the chemical solution used in the desmear process. The metal foil is typically removed by an etching process after the via holes are formed and the desmear process is complete. Conventionally, the etching solution used in this etching process also etches the metal via pads formed on the substrate below the via holes, creating voids and gaps between the via pads and the plating in the via holes, resulting in poor electrical conductivity reliability.

[0014] According to the manufacturing method of the present invention, by using a metal foil and a metal via pad in which the etching rate E1 of the metal foil and the etching rate E2 of the metal species of the metal via pad satisfy E1 / E2≧1.5 when immersed in an etching solution at 25° C. for 2 minutes, it is possible to suppress the occurrence of voids and gaps between the via pad and the plating in the via hole. Furthermore, it is usually possible to reduce the amount of depression in the metal via pad after removing the metal foil, and it is also possible to improve the adhesion strength between the insulating layer and the conductor layer even if the arithmetic mean roughness Ra of the insulating layer surface is low.

[0015] The etching rate ratio (E1 / E2) satisfies E1 / E2≧1.5, preferably E1 / E2≧1.6, more preferably E1 / E2≧1.7, or E1 / E2≧1.8, from the viewpoint of suppressing the generation of voids and gaps between the via pad and the plating in the via hole. The upper limit preferably satisfies 20≧E1 / E2, more preferably 15≧E1 / E2, and even more preferably 10≧E1 / E2 or 5≧E1 / E2. The etching rate refers to the amount of thickness reduction (μm / min) per unit time when the metal foil or the metal species of the metal via pad is immersed in a predetermined etching solution at 25°C for 2 minutes. The etching rate ratio can be measured by the method described in the Examples below. The same etching solution is used to measure the etching rates E1 and E2, and the etching solution is the same as the etching solution described in <Step (D)> below.

[0016] <Process (A)> In step (A), a resin composition layer containing a resin composition and a metal foil are laminated in this order on a substrate on which metal via pads have been formed.

[0017] 1, the step (A) may include a step of preparing a substrate 10 having metal via pads 12 formed on a support substrate 11. Examples of materials for the support substrate 11 include insulating substrates such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate.

[0018] The material of the metal via pad 12 preferably contains 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 metal via pad 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, cost, ease of patterning, etc., single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy are preferred. Single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy are more preferred. A single metal layer of copper formed by electrolytic copper plating or the like is even more preferred. The metal via pad 12 may be provided on one or both sides of the support substrate 11, and may be patterned. The metal via pad 12 may have a single-layer structure, or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are stacked.

[0019] The etching rate E2 of the metal via pad is preferably 4 μm / min or less, more preferably 2 μm / min or less, and even more preferably 1 μm / min or less, from the viewpoint of reducing the amount of depression caused by the etching solution. The lower limit of the etching rate E2 is not particularly limited, but it can be 0.001 μm / min or more. The etching rate E2 can be measured by the following method. A substrate on which a metal via pad has been formed is immersed in an etching solution at 25°C for 2 minutes. After immersion, the substrate is washed with water and dried at 80°C for 10 minutes, and the etching rate E2 can be measured by measuring the etched thickness of the cross section of the metal via pad using an SEM.

[0020] The diameter of the metal via pad is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 150 μm or less.

[0021] The thickness of the metal via pad depends on the desired design of the printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0022] As an embodiment of step (A), as shown in an example in Figure 2, a support 23 and a resin sheet 20 with metal foil formed on the support 23 in this order, a metal foil 22 and a resin composition layer 21 containing a resin composition, are used, and the resin sheet 20 with metal foil is laminated on a substrate 10 on which a metal via pad 12 is formed so that the resin composition layer 21 is bonded to the substrate 10.

[0023] The resin sheet 20 with metal foil includes a support 23, and a resin composition layer 21 containing a metal foil 22 and a resin composition provided on the support 23, and is formed in this order: the support 23, the metal foil 22, and the resin composition layer 21. The resin sheet with metal foil will be described later.

[0024] The substrate and the resin composition layer of the resin sheet with metal foil can be laminated, for example, by thermocompression bonding the resin sheet with metal foil to the substrate from the support side. Examples of a member for thermocompression bonding the resin sheet with metal foil to the substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS plate) or a metal roll (such as a SUS roll). It is preferable to press the resin sheet with metal foil with the thermocompression bonding member not directly but via an elastic material such as heat-resistant rubber so that the resin sheet with metal foil can sufficiently conform to the surface irregularities of the substrate.

[0025] The substrate and the resin composition layer may be laminated by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination may be carried out under reduced pressure conditions, preferably at a pressure of 26.7hPa or less.

[0026] 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 vacuum pressure laminator.

[0027] After lamination, the laminated resin sheet with metal foil may be smoothed under atmospheric pressure, for example, by pressing a thermocompression member from the support 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.

[0028] <<Metal foil resin sheet>> The resin sheet with metal foil includes a support and a resin composition layer containing a metal foil and a resin composition provided on the support, and is formed in the order of support, metal foil, and resin composition layer. Furthermore, when the resin sheet with metal foil is laminated on a substrate on which a metal via pad is formed, in the order of the resin composition layer and metal foil, the etching rate when the metal foil is immersed in an etching solution at 25°C for 2 minutes is defined as E1 (μm / min), and the etching rate when the metal species of the metal via pad is immersed in the same etching solution at 25°C for 2 minutes is defined as E2 (μm / min), and E1 / E2 ≧ 1.5 is satisfied. The etching rate ratio (E1 / E2) is as described above. Each layer constituting the resin sheet with metal foil will be described below.

[0029] (Support) Examples of the support include a film made of a plastic material and release paper, with a film made of a plastic material being preferred.

[0030] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0031] The surface of the support that is to be bonded to the metal foil may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0032] The support may also be a support with a release layer, which has a release layer on the surface that bonds to the metal foil. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of cellulose, alkyd resin, polyolefin resin, urethane resin, and silicone resin. Commercially available release agents may be used, such as "HP55" manufactured by Shin-Etsu Chemical Co., Ltd. The support with a release layer may also be a commercially available product, such as "SK-1," "AL-5," or "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, or "Uni-Peel" manufactured by Unitika Limited, which are PET films having a release layer primarily composed of an alkyd resin-based release agent.

[0033] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0034] (metal foil) The metal foil is preferably a different metal from the metal via pad and contains copper. The metal foil may be a foil made of a single metal such as copper, or may be a foil made of an alloy of copper and another metal. However, from the viewpoint of significantly obtaining the effects of the present invention, a foil made of an alloy of copper and another metal is preferred.

[0035] Examples of other metals include nickel, titanium, cobalt, tin, chromium, silver, magnesium, zirconium, and silicon, with nickel, titanium, and cobalt being preferred.

[0036] The metal foil is preferably a foil made of an alloy of copper and one or more metals selected from nickel, titanium, and cobalt, and more preferably a foil made of an alloy containing nickel and copper, a foil made of an alloy containing titanium and copper, or a foil made of an alloy containing nickel, cobalt, and copper.

[0037] From the viewpoint of improving the electrical conductivity reliability, the etching rate E1 of the metal foil is preferably 6 μm / min or less, more preferably 4 μm / min or less, and even more preferably 2 μm / min or less, and is preferably 0.01 μm / min or more, more preferably 0.1 μm / min or more, and even more preferably 0.2 μm / min or more. The etching rate E1 can be measured by the following method. The metal foil is immersed in an etching solution at 25°C for 2 minutes. After immersion, the foil is washed with water and dried at 80°C for 10 minutes, and the etching rate E1 can be measured by measuring the etched thickness of a cross section of the metal foil using an SEM.

[0038] The arithmetic mean roughness Ra of the surface of the metal foil that is bonded to the resin composition layer is preferably 300 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but it can be preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 5 nm or more.

[0039] From the viewpoint of obtaining the effects of the present invention remarkably, the thickness of the metal foil is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 150 nm or more. It is preferably 5000 nm or less, more preferably 3000 μm or less, and even more preferably 2500 nm or less. The metal foil may have a single-layer structure or a multi-layer structure. When the metal foil has a multi-layer structure, it is preferable that the thickness of the entire metal foil is within this range.

[0040] The method for producing the metal foil is not particularly limited, but it can be produced by known methods such as sputtering, electrolysis, and rolling.

[0041] (Resin composition layer) The resin composition layer contains a resin composition, and the resin composition preferably has sufficient hardness and insulating properties when cured. Examples of such resin compositions include (a) a composition containing a curable resin. Furthermore, the resin composition may further contain (b) an inorganic filler, (c) a thermoplastic resin, (d) a curing accelerator, and (e) other additives, as needed.

[0042] -(a) Curing resin- As the (a) curable resin, a curable resin that can be used when forming an insulating layer of a printed wiring board can be used. The (a) curable resin may be either a thermosetting resin or a photocurable resin, with a thermosetting resin being preferred.

[0043] Examples of component (a) include epoxy resins, phenolic resins, naphthol resins, benzoxazine resins, active ester resins, cyanate ester resins, carbodiimide resins, amine resins, and acid anhydride resins. Component (a) may be used singly or in any combination of two or more types in any ratio. Hereinafter, resins that can react with epoxy resins to cure the resin composition, such as phenolic resins, naphthol resins, benzoxazine resins, active ester resins, cyanate ester resins, carbodiimide resins, amine resins, and acid anhydride resins, may be collectively referred to as "curing agents." From the viewpoint of ensuring that the cured product has sufficient hardness and insulating properties, the resin composition preferably contains an epoxy resin and a curing agent as component (a), and more preferably contains an epoxy resin and an active ester resin.

[0044] Examples of epoxy resins as component (a) 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, glycidylcyclohexane-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, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins. The epoxy resin may be used alone or in combination of two or more kinds.

[0045] The resin composition preferably contains, as component (a), an epoxy resin having two or more epoxy groups in one molecule. From the viewpoint of significantly achieving the desired effects of the present invention, the proportion of the epoxy resin having two or more epoxy groups in one 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 thermosetting resin.

[0046] 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, only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin, as the thermosetting resin.

[0047] 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.

[0048] 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, naphthalene-type tetrafunctional epoxy resins, and naphthylene ether-type epoxy resins.

[0049] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin), "HP-4700", "HP-4710" (naphthalene type tetrafunctional epoxy resin), "N-690" (cresol novolac type epoxy resin), "N-695" (cresol novolac type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether type epoxy resin), manufactured by DIC Corporation; "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "NC3000L" manufactured by Nippon Kayaku Co., Ltd.; Examples include "NC3100" (biphenyl-type epoxy resin); "ESN475V" (naphthalene-type epoxy resin) and "ESN485" (naphthol novolac-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YL6121" (biphenyl-type epoxy resin), "YX4000HK" (bixylenol-type epoxy resin), and "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin), "YL7800" (fluorene-type epoxy resin), "jER1010" (solid bisphenol A-type epoxy resin), and "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR-991S" (phenolphthalimidine-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more.

[0050] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0051] 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, epoxy resins having a butadiene structure, glycidyl cyclohexane type epoxy resins, and phenolphthalimidine type epoxy resins, with bisphenol A type epoxy resins and cyclohexane type epoxy resins being more preferred.

[0052] 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" manufactured by Nippon Steel Chemical & Material Co., Ltd. (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); "EX-721" manufactured by Nagase ChemteX Corporation (a glycidyl ester type epoxy resin); "Celloxide 2021P" manufactured by Daicel Corporation (an alicyclic epoxy resin having an ester skeleton); "PB-3600" manufactured by Daicel Corporation (an epoxy resin having a butadiene structure); and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used alone or in combination of two or more.

[0053] When a liquid epoxy resin and a solid epoxy resin are used in combination as the thermosetting resin, the ratio by mass of the liquid epoxy resin to the solid epoxy resin (liquid epoxy resin:solid epoxy resin) is preferably 1:0.01 to 1:20, more preferably 1:0.1 to 1:10, and particularly preferably 1:0.2 to 1:5. When the ratio of the liquid epoxy resin to the solid epoxy resin is within this range, the desired effects of the present invention can be significantly achieved. Furthermore, when used in the form of a resin sheet with a support, appropriate adhesiveness is usually achieved. Furthermore, when used in the form of a resin sheet with a support, sufficient flexibility is usually obtained, improving handleability. Furthermore, a cured product with sufficient breaking strength can usually be obtained.

[0054] The epoxy equivalent of the epoxy resin as a thermosetting resin is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., even more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. When the epoxy equivalent is within this range, a cured product of the resin composition can be obtained with sufficient crosslink density. The epoxy equivalent is the mass of an epoxy resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0055] From the viewpoint of significantly achieving the desired effects of the present invention, the weight average molecular weight (Mw) of the epoxy resin as the thermosetting resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight average molecular weight of the epoxy resin is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0056] The content of the epoxy resin as a thermosetting resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition, from the viewpoint of obtaining a cured product exhibiting good mechanical strength and insulation reliability. The upper limit of the epoxy resin content is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoint of significantly achieving the desired effects of the present invention. In the present invention, the content of each component in the resin composition is the value based on 100% by mass of the nonvolatile components in the resin composition, unless otherwise specified.

[0057] As the activated ester resin used as the thermosetting resin, a resin having one or more activated ester groups per molecule can be used. Among these, preferred activated 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, an activated ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an activated ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred.

[0058] Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0059] 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, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0060] Preferred 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.

[0061] Commercially available activated ester resins include those containing dicyclopentadiene-type diphenol structures, such as "EXB9451," "EXB9460," "EXB9460S," "HPC-8000-65T," "HPC-8000H-65TM," and "EXB-8000L-65TM" (manufactured by DIC Corporation); those containing naphthalene structures, such as "EXB9416-70BK," "EXB-8150-65T," and "HPB-8151-62T" (manufactured by DIC Corporation); and those containing acetylated phenol novolac. Examples of active ester resins include "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester resins containing benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation); active ester resins that are acetylated phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation); and active ester resins that are benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation).

[0062] As the thermosetting resin, a phenolic resin or a naphtholic resin having a novolac structure is preferred from the viewpoint of heat resistance and water resistance. Furthermore, from the viewpoint of adhesion to the conductor layer, a nitrogen-containing phenolic curing agent is preferred, and a triazine skeleton-containing phenolic resin is more preferred.

[0063] Specific examples of phenol-based resins and naphthol-based 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.; "SN170," "SN180," "SN190," "SN475," "SN485," "SN495," "SN-495V," "SN375," and "SN395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "TD-2090," "LA-7052," "LA-7054," "LA-1356," "LA-3018-50P," and "EXB-9500" manufactured by DIC Corporation.

[0064] Specific examples of benzoxazine-based resins as thermosetting resins include "JBZ-OD100" (benzoxazine ring equivalent weight 218), "JBZ-OP100D" (benzoxazine ring equivalent weight 218), and "ODA-BOZ" (benzoxazine ring equivalent weight 218) manufactured by JFE Chemical Corporation; "Pd" (benzoxazine ring equivalent weight 217) and "Fa" (benzoxazine ring equivalent weight 217) manufactured by Shikoku Chemicals Corporation; and "HFB2006M" (benzoxazine ring equivalent weight 432) manufactured by Showa Polymer Co., Ltd.

[0065] Examples of cyanate ester resins as thermosetting resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac, cresol novolac, etc.; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate ester resins include "PT30," "PT30S," and "PT60" (phenol novolac-type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230," "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted to form a trimer), and "BADCy" (bisphenol A dicyanate), all manufactured by Lonza Japan.

[0066] Specific examples of carbodiimide resins as thermosetting resins include Carbodilite (registered trademark) V-03 (carbodiimide group equivalent: 216, V-05 (carbodiimide group equivalent: 216), V-07 (carbodiimide group equivalent: 200), and V-09 (carbodiimide group equivalent: 200), all manufactured by Nisshinbo Chemical Inc.; and Stavaxol (registered trademark) P (carbodiimide group equivalent: 302), all manufactured by Rhein Chemie.

[0067] Examples of the amine resin as a thermosetting resin include resins having one or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Among these, aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxybenzoyl). Examples of suitable amine resins include 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine resins may be used, such as "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0068] Examples of acid anhydride resins as thermosetting resins include resins having one or more acid anhydride groups in one molecule. Specific examples of acid anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable anhydrides include anhydrides, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid.

[0069] The curing agent for the thermosetting resin is preferably any one of a phenolic resin, a naphthol resin, a benzoxazine resin, an active ester resin, a cyanate ester resin, a carbodiimide resin, an amine resin, and an acid anhydride resin, more preferably any one of an active ester resin, a phenolic resin, a naphthol resin, and a cyanate ester resin, and more preferably one or more selected from an active ester resin and a cyanate ester resin.

[0070] When the thermosetting resin contains an epoxy resin and a curing agent, the ratio of the amount of epoxy resin to the total amount of curing agent, expressed as the ratio of [total number of epoxy groups in the epoxy resin] to [total number of reactive groups in the curing agent], is preferably in the range of 1:0.01 to 1:5, more preferably 1:0.05 to 1:3, and even more preferably 1:0.1 to 1:2. Here, the "number of epoxy groups in the epoxy resin" refers to the sum of all values ​​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 sum of all values ​​obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the active group equivalent. By maintaining the ratio of epoxy resin to curing agent within this range as the thermosetting resin, a cured product with excellent flexibility can be obtained.

[0071] From the viewpoint of obtaining a cured product with excellent flexibility, the content of the curing agent as a thermosetting resin is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% 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, even more preferably 25% by mass or less.

[0072] From the viewpoint of significantly obtaining the effects of the present invention, the content of the thermosetting resin is preferably 10% by mass or more, more preferably 13% by mass or more, even more preferably 15% by mass or more, relative to 100% by mass of non-volatile components in the resin composition, and is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less.

[0073] -(b) Inorganic filler- The resin composition contains (b) an inorganic filler. The inorganic filler is an inorganic compound. Examples of inorganic filler materials include silica, alumina, aluminosilicate, 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, calcium carbonate and silica are preferred, with silica being particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Furthermore, spherical silica is preferred. (b) The inorganic filler may be used alone or in combination of two or more kinds.

[0074] Examples of commercially available products of component (b) include "UFP-30" and "ASFP-20" manufactured by Denka; "SP60-05," "SP507-05," and "SPH516-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," and "YA010C" manufactured by Admatechs Co., Ltd.; "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation; and "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.

[0075] The specific surface area of ​​component (b) is preferably 1 m 2 / g or more, more preferably 2m 2 / g or more, particularly preferably 3m 2 / g or more. There is no particular upper limit, but it is preferably 60m 2 / g or less, 50m 2 / g or less or 40m 2 The specific surface area is determined by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0076] From the viewpoint of significantly achieving the desired effects of the present invention, the average particle size of component (b) is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less.

[0077] The average particle size of component (b) can be measured using a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the inorganic filler is created using a laser diffraction / scattering particle size distribution analyzer, 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 them ultrasonically for 10 minutes. The volumetric particle size distribution of component (b) is measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0078] From the viewpoint of improving moisture resistance and dispersibility, it is preferable that component (b) be treated with a surface treatment agent. Examples of surface treatment agents 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. Among these, from the viewpoint of significantly achieving the effects of the present invention, vinylsilane coupling agents, (meth)acrylic coupling agents, and aminosilane coupling agents are preferred, and aminosilane coupling agents are more preferred. Furthermore, the surface treatment agents may be used alone or in any combination of two or more.

[0079] 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), "KBM-4803" (long-chain epoxy-type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0080] The degree of surface treatment with the surface treatment agent is preferably within a predetermined range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100 parts by mass of the 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.

[0081] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 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 Less than 0.8 mg / m is preferred 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0082] The carbon amount per unit surface area of ​​the inorganic filler can be measured after the surface-treated 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 a 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 inorganic filler can be measured using a carbon analyzer. The carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

[0083] From the viewpoint of achieving a significant effect of the present invention, the content of the inorganic filler is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

[0084] -(c)Thermoplastic resin- The resin composition may contain (c) a thermoplastic resin as an optional component. Examples of (c) thermoplastic resins include phenoxy resins, polyvinyl acetal resins, polyolefin resins, polyimide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polyetheretherketone resins, and polyester resins, with phenoxy resins being preferred. The thermoplastic resins may be used alone or in combination of two or more.

[0085] The polystyrene-equivalent weight-average molecular weight of the (c) thermoplastic resin is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 18,000 or more. The upper limit is preferably 100,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. The polystyrene-equivalent weight-average molecular weight of the (c) thermoplastic resin is measured by gel permeation chromatography (GPC). Specifically, the polystyrene-equivalent weight-average molecular weight of the (c) thermoplastic resin is measured using a Shimadzu LC-9A / RID-6A measuring instrument, a Showa Denko Shodex K-800P / K-804L / K-804L column, and chloroform or the like as the mobile phase at a column temperature of 40°C, and can be calculated using a calibration curve of standard polystyrene.

[0086] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. 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), "YX7800BH40" (phenoxy resin containing a fluorene 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," "YL7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0087] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, manufactured by Denki Kagaku Kogyo Co., Ltd., and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, manufactured by Sekisui Chemical Co., Ltd.

[0088] Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A No. 2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A Nos. 2002-12667 and 2000-319386).

[0089] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0090] A specific example of polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd. A specific example of polyphenylene ether resin is "OPE-2St 1200" oligophenylene ether styrene resin manufactured by Mitsubishi Gas Chemical Co., Ltd. A specific example of polyetheretherketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd. A specific example of polyetherimide resin is "Ultem" manufactured by GE Corporation.

[0091] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0092] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin elastomers such as polypropylene and ethylene-propylene block copolymer.

[0093] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

[0094] Among these, phenoxy resin and polyvinyl acetal resin are preferred as the (c) thermoplastic resin. Therefore, in a preferred embodiment, the thermoplastic resin comprises one or more selected from the group consisting of phenoxy resin and polyvinyl acetal resin. Among these, phenoxy resin is preferred as the thermoplastic resin, and phenoxy resin having a weight average molecular weight of 40,000 or more is particularly preferred.

[0095] The content of the (c) thermoplastic resin is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition, and the upper limit is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0096] -(d) Curing accelerator- The resin composition may contain (d) a curing accelerator as an optional component. Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Amine-based curing accelerators and imidazole-based curing accelerators are preferred, and amine-based curing accelerators are more preferred. One type of curing accelerator may be used alone, or two or more types may be used in combination.

[0097] Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate, with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

[0098] 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.

[0099] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2, 4-Diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, Examples of the imidazole compound include imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins, and 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred.

[0100] As the imidazole-based curing accelerator, commercially available products may be used, for example, "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0101] Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Examples of suitable biguanide include 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide. Of these, dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0102] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0103] The content of (d) the curing accelerator is, when the non-volatile components in the resin composition are taken as 100% by mass, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.03% by mass or more, and is preferably 1% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

[0104] -(e) Other additives- In addition to the above-mentioned components, the resin composition may further contain other additives as optional components. Examples of such additives include flame retardants, organic fillers, organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds, thickeners, antifoaming agents, leveling agents, adhesion promoters, and colorants. These additives may be used alone or in combination of two or more in any ratio.

[0105] The thickness of the resin composition layer is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 40 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product of the resin composition that has excellent insulating properties even when the cured product is thin. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 2 μm or more, or 5 μm or more, etc.

[0106] A resin sheet with metal foil can be produced, for example, by forming a metal foil on a support, preparing a resin varnish by dissolving a resin composition in an organic solvent, applying this resin varnish to the metal foil using a die coater or the like, and then drying it to form a resin composition layer.

[0107] Examples of organic solvents include ketones such as methyl ethyl ketone (MEK) and cyclohexanone, aromatic hydrocarbons such as xylene and tetramethylbenzene, glycol ethers 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, esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate, aliphatic hydrocarbons such as octane and decane, and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These may be used alone or in combination of two or more.

[0108] In another embodiment of step (A), a metal foil-attached sheet, in which a metal foil is formed on a support, is laminated on a substrate on which metal via pads are formed, so that the metal foil is bonded to the substrate via a resin composition layer. The metal foil-attached sheet includes a support and a metal foil provided on the support. The support and metal foil are the same as the support and metal foil in the metal foil-attached resin sheet.

[0109] In another embodiment of step (A), a resin sheet is used, which includes a support and a resin composition layer formed from a resin composition provided on the support. First, the resin sheet is laminated so that the resin composition layer is bonded to the substrate, and after peeling off the support, the metal foil of the metal foil-attached sheet is laminated so that the metal foil is bonded to the resin composition layer. Alternatively, instead of using a resin sheet, the resin composition may be applied directly to the substrate to form a resin composition layer. The resin composition and resin composition layer are the same as the resin composition and resin composition layer in the metal foil-attached resin sheet. The lamination of the resin composition layer and the metal foil-attached sheet can be performed under the same conditions as the lamination of the substrate and the metal foil-attached resin sheet.

[0110] <Process (B)> In step (B), the resin composition layer 21 is cured to form an insulating layer 21a, as shown in Fig. 3. The curing conditions for the resin composition layer are not particularly limited, and the conditions employed for forming an insulating layer of a printed wiring board may be used. The resin composition layer may be cured by irradiation with active energy rays such as ultraviolet rays, but is usually thermally cured by heating.

[0111] For example, the thermal curing conditions for the resin composition layer vary depending on the type of resin composition, but in one embodiment, 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.

[0112] Before thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature of 50°C to 120°C, preferably 60°C to 115°C, more preferably 70°C to 110°C for 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes.

[0113] <Process (C)> In step (C), as shown in FIG. 4, the metal foil 22 and the insulating layer 21a are punched to form via holes 13 on the metal via pads 12. As shown in FIG.

[0114] In one embodiment of step (C), a laser is irradiated onto the metal foil 22 and the insulating layer 21a to drill holes in the insulating layer 21a and the metal foil 22, thereby forming via holes 13. If necessary, a mask (not shown) may be provided on the metal foil 22 before the laser is irradiated to form the via holes 13.

[0115] The shape of the via hole is not particularly limited, but is generally circular (approximately circular). The opening diameter (top diameter) of the via hole that can be formed by performing step (C) is preferably 5 μm or more, more preferably 10 μm or more, more preferably 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more, and is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less, or 70 μm or less. Here, the opening diameter (top diameter) of the via hole refers to the diameter of the opening of the via hole at the surface of the insulating layer.

[0116] Examples of laser light sources that can be used to form via holes include CO2 lasers (carbon dioxide lasers), UV-YAG lasers, UV lasers, YAG lasers, excimer lasers, etc. Among these, CO2 lasers and UV-YAG lasers are preferred from the viewpoints of processing speed and cost.

[0117] In irradiating the laser, the number of shots is preferably 5 or less, more preferably 2 or less, from the viewpoint of improving the processability of the via hole. In order to keep the number of shots within the above range, it is preferable to set the laser energy and pulse width to a certain value or more. The laser output is preferably 0.1 W or more, more preferably 0.3 W or more, even more preferably 0.5 W or more, and preferably 30 W or less, more preferably 10 W or less, even more preferably 5 W or less. In addition, the laser pulse width is preferably 0.5 μsec or more, more preferably 1 μsec or more, even more preferably 3 μsec or more, and preferably 30 μsec or less, more preferably 15 μsec or less, even more preferably 10 μsec or less.

[0118] The via holes can be formed using a commercially available laser device. Examples of commercially available carbon dioxide gas laser devices include the "LC-2E21B / 1C" manufactured by Hitachi Via Mechanics, the "ML605GTWII" manufactured by Mitsubishi Electric Corporation, the "605GTWIII(-P)" manufactured by Mitsubishi Electric Corporation, and a substrate drilling laser processing machine manufactured by Matsushita Welding Systems Co., Ltd. Examples of UV-YAG laser devices include the "LU-2L212 / M50L" manufactured by Via Mechanics.

[0119] A step of removing the support may be carried out after step (B) and before step (D). The step of removing the support is preferably carried out after step (C) and before step (D). The support may be peeled off and removed manually, or may be peeled off and removed mechanically using an automatic peeling device.

[0120] After step (C) and before step (D), a desmearing process may be performed to remove smears in the via holes. The procedure and conditions for the desmearing process are not particularly limited as long as the smears in the via holes (on the metal via pads) can be removed. In addition, if the support has a release layer, it is preferable to remove the release layer by the desmearing process. The desmearing process may, for example, involve a swelling process using a swelling liquid, a roughening process using an oxidizing agent, and a neutralization process using a neutralizing liquid, performed in this order.

[0121] Examples of swelling solutions used in the desmear treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Examples of alkaline solutions include sodium hydroxide solutions and potassium hydroxide solutions. Examples of commercially available swelling solutions include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. The swelling treatment using a swelling solution is not particularly limited, but can be carried out by, for example, immersing the object in a swelling solution at 30°C to 90°C for 1 to 20 minutes. To achieve the most pronounced effects of the present invention, it is preferable to immerse the object in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0122] Examples of oxidizing agents used in desmear treatment include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidizing agent such as alkaline permanganate solution is preferably carried out by immersing the target object in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0123] The neutralizing solution used in the desmear treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan can be cited. Treatment with a neutralizing solution can be carried out by immersing the surface that has been desmeared with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 1 to 30 minutes. From the standpoint of workability, etc., a method in which the object that has been desmeared with an oxidizing agent is immersed in a neutralizing solution at 30°C to 70°C for 3 to 20 minutes is preferred.

[0124] <Process (D)> In step (D), the metal foil 22 is removed, as shown in Fig. 5. The method for removing the metal foil 22 may be a method capable of removing the metal foil 22 without damaging the surface of the insulating layer 21a, and the metal foil 22 is removed by etching such as wet etching.

[0125] In wet etching, a solution that dissolves the metal that forms the metal foil 22 and that causes the etching rates E1 and E2 of the metal foil to fall within the above-mentioned ranges is used as the etching liquid.

[0126] Such an etching solution is preferably at least one selected from the group consisting of an etching solution containing any one of hydrogen peroxide, sulfuric acid, and nitric acid; an etching solution containing a fluoride; an etching solution containing hydrogen peroxide and aqueous ammonia; and an etching solution containing any one of copper sulfate, iron sulfate, and copper chloride.

[0127] When the metal foil contains copper, it is preferable to use one or more etching solutions selected from the group consisting of an etching solution containing any one of hydrogen peroxide, sulfuric acid, and nitric acid; an etching solution containing a fluoride; an etching solution containing hydrogen peroxide and aqueous ammonia; and an etching solution containing any one of copper sulfate, iron sulfate, and copper chloride.

[0128] When the metal foil is an alloy containing nickel and copper, it is preferable to use an etching solution containing any one of hydrogen peroxide, sulfuric acid, and nitric acid; and an etching solution containing any one of copper sulfate, iron sulfate, and copper chloride.

[0129] When the metal foil is an alloy containing titanium and copper, it is preferable to use an etching solution containing hydrogen peroxide and aqueous ammonia.

[0130] Examples of etching solutions containing any of hydrogen peroxide, sulfuric acid, and nitric acid include etching solutions containing sulfuric acid and hydrogen peroxide, and etching solutions containing nitric acid and hydrogen peroxide. Commercially available etching solutions containing any of hydrogen peroxide, sulfuric acid, and nitric acid can be used. Examples of commercially available products include "NH-1866" (etching solution containing nitric acid and hydrogen peroxide) manufactured by MEC Corporation, "SAC" (etching solution containing sulfuric acid and hydrogen peroxide) manufactured by JCU Corporation, and "CPE-800D" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0131] An example of an etching solution containing fluoride is an aqueous solution containing 1% by weight of hydrogen peroxide and 1% by weight of hydrofluoric acid. Commercially available etching solutions containing fluoride can be used, such as "Clean Etch Putax" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0132] The etching solution containing hydrogen peroxide and aqueous ammonia can be an alkaline etching solution whose pH is adjusted with aqueous ammonia. The pH is preferably 7.1 or higher, more preferably 7.3 or higher, and even more preferably 7.5 or higher, and is preferably 14 or lower, more preferably 13 or lower, and even more preferably 10 or lower. A commercially available product can be used as the etching solution containing hydrogen peroxide and aqueous ammonia. An example of a commercially available product is "WCT-T" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0133] Examples of etching solutions containing any of copper sulfate, iron sulfate, and copper chloride include etching solutions containing copper sulfate, iron sulfate, and copper chloride, with iron sulfate being preferred. Commercially available etching solutions containing any of copper sulfate, iron sulfate, and copper chloride can be used. Examples of commercially available products include "SE-300" manufactured by Meltex and "CupraEtch DE" manufactured by Atotech.

[0134] The temperature at which step (D) is carried out is not particularly limited as long as it is a temperature at which the metal foil can be effectively removed, but is preferably 10°C or higher, more preferably 15°C or higher, even more preferably 20°C or higher, and is preferably 80°C or lower, more preferably 60°C or lower, even more preferably 50°C or lower.

[0135] The time for carrying out step (D) varies depending on the thickness of the metal foil and the type of metal forming the metal foil, but is preferably 0.05 to 60 minutes, more preferably 0.1 to 15 minutes.

[0136] Even if residues of the support and / or release layer are present on the metal foil, such residues can be removed together with the metal foil in step (D).

[0137] The arithmetic mean roughness (Ra) of the exposed surface of the insulating layer after step (D) is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 100 nm or less, still more preferably 80 nm or less, 70 nm or less, or 60 nm or less. The lower limit of the Ra value is preferably 0.5 nm or more, more preferably 1 nm or more. The arithmetic mean roughness of the insulating layer can be measured using a non-contact surface roughness meter, and specifically, can be measured by the method described in the examples.

[0138] <Process (E)> In step (E), a conductor layer is formed on the insulating layer. Specifically, a conductor layer 30 is formed on the insulating layer 21a and in the via holes 13, as shown in an example in FIG.

[0139] The conductive material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains 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 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 conductor layer, cost, ease of patterning, etc., single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy are preferred. Single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy are more preferred, and single metal layers of copper are even more preferred.

[0140] The conductor layer may have a single layer structure, or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0141] The thickness of the conductor layer depends on the desired design of the printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0142] The conductor layer can be formed by plating, sputtering, vapor deposition, or the like, with plating being preferred. The conductor layer can be formed by plating the surface of the insulating layer using, for example, a semi-additive method, a full-additive method, or the like, to form a conductor layer having a desired wiring pattern. Among these, from the viewpoint of ease of production, the semi-additive method is preferred. Below, an example of forming a conductor layer by a semi-additive method is shown.

[0143] A plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. A metal layer is formed on the exposed plating seed layer by electrolytic plating, and then the mask pattern is removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, thereby forming a conductor layer having the desired wiring pattern.

[0144] A printed wiring board manufactured by the manufacturing method of the present invention can usually suppress the amount of denting of the metallic via pad even after removing the metal foil. As shown in FIG. 9, the amount of denting is the difference D between the thickest point 12b of the metallic via pad 12 before removing the metal foil 22 and the thinnest point 12c of the metallic via pad 12 after removing the metal foil 22. The amount of denting is preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 0.5 μm or less. There is no particular restriction on the lower limit, but it can be 0.01 μm or more. The amount of denting can be measured by the method described in the Examples below.

[0145] In the present invention, the etching rate E1 of the metal foil and the etching rate E2 of the metal via pad satisfy a predetermined relationship, so that the occurrence of voids, interfaces, and gaps between the via pad and the plating in the via hole can be suppressed. In the printed wiring board manufactured by the manufacturing method of the present invention, voids, interfaces, and gaps do not occur between the via pad and the plating in the via hole. The voids, interfaces, and gaps can be observed by the method described in the examples below.

[0146] In a printed wiring board produced by the production method of the present invention, the resin composition is heated at 100°C for 30 minutes, and then thermally cured at 170°C for 30 minutes to obtain a cured product, which can enhance the plating peel strength between the insulating layer and the plating. For example, when an insulating layer and a plated conductor layer are formed using the method described in the Examples below, the peel strength between the insulating layer and the conductor layer is preferably 0.3 kgf / cm or more, more preferably 0.4 kgf / cm or more, and particularly preferably 0.5 kgf / cm or more. The upper limit of the plating peel strength is not particularly limited, but can be, for example, 10.0 kgf / cm or less. Peel strength can be measured using the method described in the Examples below.

[0147] [Semiconductor Devices] A semiconductor device according to one embodiment of the present invention includes a printed wiring board manufactured by the above-described method for manufacturing a printed wiring board.

[0148] Examples of semiconductor devices include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0149] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

[0150] Example 1 (1) Preparation of ultra-thin metal foil 1 A support with a release layer was prepared by coating a PET film support with a 15% solution of HP55 (Shin-Etsu Chemical Co., Ltd., cellulose) in MEK and cyclohexanone and drying it. A 200 nm thick Ni-Cu alloy layer was then sputtered onto the release layer to form a metal foil, preparing ultrathin metal foil 1 with a support. The arithmetic mean roughness of the metal foil was 25 nm.

[0151] (2) Preparation of Resin Composition 1 Bixylenol type epoxy resin (Mitsubishi Chemical Corporation "YX4000HK", epoxy equivalent: approx. 185 g / eq.) 6 parts, naphthalene type epoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd. "ESN475V", epoxy equivalent: approx. 332 g / eq.) 5 parts, bisphenol AF type epoxy resin (Mitsubishi Chemical Corporation "YL7760", epoxy equivalent: approx. 238 g / eq.) 15 parts, naphthylene ether type epoxy resin (DIC Corporation "HP6000L", epoxy equivalent: approx. 15 parts), Two parts of a cyclohexane-type epoxy resin ("ZX1658GS" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight: approximately 135 g / eq.), two parts of a cyclohexane-type epoxy resin ("YL7500BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of cyclohexanone and methyl ethyl ketone (MEK) with a solids content of 30 mass%, Mw=44,000) were heated and dissolved with stirring in a mixed solvent of 20 parts solvent naphtha and 10 parts cyclohexanone. After cooling to room temperature, 4 parts of a triazine skeleton-containing cresol novolac resin (DIC Corporation's "LA-3018-50P," hydroxyl group equivalent weight approximately 151 g / eq., 50% solids solution in 2-methoxypropanol), 6 parts of an active ester resin (DIC Corporation's "EXB-8000L-65™," active group equivalent weight approximately 220 g / eq., toluene solution with 65% nonvolatile content by mass), 60 parts of inorganic filler 1, and 0.05 parts of an amine curing accelerator (4-dimethylaminopyridine (DMAP)) were mixed and dispersed uniformly using a high-speed rotary mixer. The mixture was then filtered through a cartridge filter (ROKITECHNO Corporation's "SHP020") to prepare Resin Composition 1. The inorganic filler 1 was prepared by surface treating 100 parts of "SC2500SQ" manufactured by Admatec Co., Ltd. with 1 part of N-phenyl-3-aminopropyltrimethoxysilane (KBM573 manufactured by Shin-Etsu Chemical Co., Ltd.).

[0152] (3) Preparation of ultra-thin metal foil-attached resin sheet 1 Resin composition 1 was applied to the Ni-Cu alloy layer of the supported ultrathin metal foil 1 using a die coater so that the thickness of the resin composition layer after drying would be 40 μm, and then dried at 80°C to 120°C (average 100°C) for 10 minutes to obtain resin sheet 1.

[0153] (4) Preparation of evaluation board Resin sheet 1 with ultrathin metal foil was laminated to both sides of a wiring board with a Cu wiring pattern and 100 μm diameter Cu pads using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator, CVP700) so that the resin composition layer was in contact with the wiring board. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, and then pressing at 130°C and a pressure of 0.74 MPa for 45 seconds. Next, a heat press was performed at 120°C and a pressure of 0.5 MPa for 75 seconds. The laminate was vacuum laminated and then thermally cured at 100°C for 30 minutes, followed by 30 minutes at 170°C to form an insulating layer.

[0154] After thermal curing, a via hole with a diameter of approximately 50 μm was formed on the 100 μm Cu pad using a CO2 laser. The CO2 laser processing was performed using a carbon dioxide gas laser manufactured by Hitachi Via Mechanics Co., Ltd., with an output of 0.6 W, a pulse width of 3 μs, and two shots.

[0155] After the laser processing, the PET film was peeled off, and desmearing was carried out in the following order of 1) to 3) to remove the smear on the pad and the release layer on the ultrathin metal foil. 1) Immersion in swelling solution (Atotech Japan's Swelling Dip Securigant P (aqueous solution of glycol ethers and sodium hydroxide) containing diethylene glycol monobutyl ether, 60°C for 10 minutes) 2) Immersion in an oxidizing agent (roughening solution) (Concentrate Compact P (KMnO4: 60 g / L, NaOH: 40 g / L aqueous solution, manufactured by Atotech Japan, at 80°C for 20 minutes) 3) Neutralizing solution (Reduction Showreusin Securigant P (aqueous solution of sulfuric acid) manufactured by Atotech Japan, 40°C for 5 minutes)

[0156] After the desmear treatment, the substrate was immersed in an etching solution (NH-1866 aqueous solution, nitric acid / hydrogen peroxide system, manufactured by MEC Co., Ltd.) for 1 minute and 30 seconds to remove the Ni-Cu alloy layer.

[0157] (5) Observation of the evaluation board (observation of the amount of depression of the Cu pad (metal via pad)) After removing the Ni-Cu alloy layer, the amount of dent in the Cu pad was measured by cross-sectional observation using FIB. The amount of dent was the difference between the thickest point of the Cu pad before removing the Ni-Cu alloy layer and the thinnest point of the Cu pad after removing the Ni-Cu alloy layer.

[0158] (6) Observation of voids, interfaces, and gaps, and measurement of plating peel strength The substrate from which the Ni-Cu alloy layer had been removed was immersed in an electroless plating solution containing PdCl2 at 40°C for 5 minutes, and then in an electroless copper plating solution at 25°C for 20 minutes. The substrate was then heated at 150°C for 30 minutes and annealed. Copper sulfate electroplating was performed to form a conductor layer with a thickness of 20 μm. An annealing treatment was then performed at 200°C for 60 minutes. A cross-section of a 50 μm diameter via was then observed using an FIB to check for the presence or absence of voids, and the presence or absence of gaps at the interface with the Cu pad. Evaluation was based on the following criteria. ◯: No voids, interfaces or gaps occurred. ×: Voids, interfaces and gaps are generated.

[0159] After electrolytic copper plating, a slit was made on the electrolytic copper-plated surface to enclose a rectangular area 10 mm wide and 100 mm long. One end of the rectangular area was peeled off and gripped with a gripper (TSE Autocom type testing machine "AC-50C-SL"). The rectangular area was peeled off vertically at room temperature at a rate of 50 mm / min, and the load (kgf / cm) when 35 mm was peeled off was measured as the plating peel strength.

[0160] (7) Measurement of arithmetic surface roughness Ra The arithmetic mean roughness (Ra) of the insulating layer of the substrate after removing the Ni-Cu alloy layer was measured. Measurements were performed using a non-contact surface roughness meter (WYKO NT3300 manufactured by Veeco Instruments) in VSI mode with a 50x lens, with a measurement range of 121 μm × 92 μm. Measurements were performed at 10 measurement points, and the average value was taken as the Ra value.

[0161] (8) Measurement of etching rate ratio A substrate (substrate 10 in FIG. 1) on which an ultrathin metal foil 1 and metal via pads were formed by electrolytic copper plating was immersed in an aqueous solution of NH-1866 (manufactured by MEC) (temperature: 25°C) for 2 minutes. After rinsing with water and drying at 80°C for 10 minutes, a cross section was formed by polishing, including the ultrathin metal foil before immersion and the substrate on which the electrolytic copper plating was formed. The etched thickness was then measured using an SEM, and the etching rate ratio (E1 / E2) between the ultrathin metal foil 1 and the electrolytic copper plating was calculated.

[0162] <Example 2> In Example 1, 1) The Ni-Cu alloy layer is changed to a Ti-Cu alloy layer, 2) The etching solution (NH-1866 aqueous solution, nitric acid / hydrogen peroxide system, manufactured by MEC Co., Ltd.) was changed to WLC-T (ammonia / hydrogen peroxide system, manufactured by Mitsubishi Gas Chemical Co., Ltd.) aqueous solution adjusted to pH 8 with ammonia water. Other than the above, the procedure was the same as in Example 1.

[0163] Example 3 In Example 1, 1) The Ni-Cu alloy layer was replaced with a metal foil (JXUT-I, manufactured by JX Metals Corporation, thickness 2 μm) made of an alloy containing Ni, Co, and Cu. 2) The etching solution (NH-1866 aqueous solution, nitric acid / hydrogen peroxide system, manufactured by MEC) was changed to SAC (sulfuric acid / hydrogen peroxide aqueous solution, manufactured by JCU). Other than the above, the procedure was the same as in Example 1.

[0164] Example 4 In Example 3, the etching solution (manufactured by JCU, SAC (aqueous solution of sulfuric acid / hydrogen peroxide)) was changed to an iron ion-containing flash etching solution (manufactured by Meltex, SE-300). Except for the above, the same procedure as in Example 3 was carried out.

[0165] <Example 5> In Example 1, 1) The Ni-Cu alloy layer was replaced with a metal foil (manufactured using a sputtering device, thickness 150 nm) made of an alloy containing Ni, Ti, and Cu. 2) The etching solution (NH-1866 aqueous solution, nitric acid / hydrogen peroxide system, manufactured by MEC Co., Ltd.) was changed to an etching solution (Clean Etch Putax (aqueous solution containing 1% by mass of hydrofluoric acid and 1% by mass of hydrogen peroxide, manufactured by Mitsubishi Gas Chemical Co., Ltd.)). Other than the above, the procedure was the same as in Example 1.

[0166] <Comparative Example 1> In Example 3, the metal foil made of an alloy of Ni, Co, and Cu (manufactured by JX Metals Corporation, JXUT-I, thickness 2 μm) was changed to a metal foil with an ultra-thin copper foil (manufactured by Mitsui Kinzoku Co., Ltd., MT-Ex, thickness 3 μm). Except for the above, the same procedure as in Example 3 was carried out.

[0167] [Table 1] [Explanation of symbols]

[0168] 10 Substrate 11 Support substrate 12 Metal via pads 12b Thickest metal via pad 12c Thinnest metal via pad thickness 13 Beer Hall 20 Metal foil-attached resin sheet 21 Resin composition layer 21a Insulating layer 22 Metal foil 23 Support 30 Conductor Layer 41 Interface D Difference between the thickest and thinnest metal via pads

Claims

1. (A) a step of laminating a resin composition layer containing a resin composition and a metal foil in this order on a substrate on which a metal via pad has been formed; (B) a step of curing the resin composition layer to form an insulating layer; (C) forming a via hole; (D) removing the metal foil; and (E) forming a conductor layer, A method for manufacturing a printed wiring board, wherein E1 / E2≧1.5 is satisfied when the etching rate of a metal foil when immersed in an etching solution at 25° C. for 2 minutes is E1 (μm / min) and the etching rate of a metal species of a metal via pad when immersed in the etching solution at 25° C. for 2 minutes is E2 (μm / min).

2. 2. The method for producing a printed wiring board according to claim 1, wherein step (A) uses a support and a resin sheet with a metal foil formed on the support in this order, and laminates the resin sheet with the metal foil on a substrate on which a metal via pad is formed so that the resin composition layer is bonded to the substrate.

3. 2. The method for producing a printed wiring board according to claim 1, wherein the step (A) comprises laminating a metal foil-covered sheet, in which a metal foil is formed on a support, on a substrate on which a metal via pad is formed, so that the metal foil is bonded to the substrate via a resin composition layer.

4. The method for producing a printed wiring board according to claim 2 or 3, further comprising a step of removing the support after step (B) and before step (C).

5. 5. The method for manufacturing a printed wiring board according to claim 1, wherein the diameter of the metal via pad is 30 μm or more.

6. 6. The method for producing a printed wiring board according to claim 1, wherein the opening diameter of the via hole is 5 μm or more.

7. The method for producing a printed wiring board according to any one of claims 1 to 6, wherein the resin composition layer has a thickness of 2 µm or more and 50 µm or less.

8. The method for producing a printed wiring board according to any one of claims 1 to 7, wherein the resin composition contains a curable resin.

9. The method for producing a printed wiring board according to any one of claims 1 to 8, wherein the metal foil comprises a foil made of an alloy of copper and one or more metals selected from nickel, titanium, and cobalt.

10. The method for manufacturing a printed wiring board according to any one of claims 1 to 9, wherein the metal via pad contains copper.

11. The method for producing a printed wiring board according to any one of claims 1 to 10, wherein the etching solution is at least one selected from the group consisting of an etching solution containing any one of hydrogen peroxide, sulfuric acid, and nitric acid; an etching solution containing a fluoride; an etching solution containing hydrogen peroxide and aqueous ammonia; and an etching solution containing any one of copper sulfate, iron sulfate, and copper chloride.

Images