Method for manufacturing a circuit board and resin sheet

Abstract

To provide a method for manufacturing a circuit board, which uses a resin sheet having a thin resin composition layer of 25 μm or less, and yet can manufacture a circuit board by peeling off a support with good peelability.SOLUTION: A method for manufacturing a circuit board using a resin sheet including a support having a plastic film layer and a release layer, and a resin composition layer formed on the support includes the steps of laminating a resin sheet and an inner layer substrate such that the resin composition layer and the inner layer substrate are bonded to each other, curing the resin composition layer to form an insulating layer, and peeling off the support, and the thickness of the resin composition layer is 25 μm or less, and a lamination temperature α between the resin sheet and the inner layer substrate, a lamination pressure β between the resin sheet and the inner layer substrate, and an endothermic peak temperature γ of the release agent have a specific relationship.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a circuit board and a resin sheet that can be used in the manufacturing method.

Background Art

[0002] Some circuit boards such as printed wiring boards and package substrates have a multilayer structure including a plurality of insulating layers and conductor layers respectively. The insulating layer is formed, for example, by a cured product of a resin composition containing a curable resin. As a method of forming the insulating layer by a cured product of the resin composition, a method using a resin sheet provided with a resin composition layer containing the resin composition has been proposed. For example, a method has been proposed in which a resin sheet including a support and a resin composition layer is laminated with an inner layer substrate, and the resin composition layer is cured to form an insulating layer (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, demands for higher multilayer and higher density of wiring on circuit boards have been increasing. Generally, there is a limit to the overall thickness of the circuit board, and the impedance of the wiring is required to be appropriately controlled. Therefore, when performing higher multilayer and higher density of wiring, the conductor layer for forming the wiring is required to be formed thinly. Also, the insulating layer for insulating such a thin conductor layer is also required to be formed thinly. A thin insulating layer is usually formed using a resin sheet including a thin resin composition layer.

[0005] When the resin composition layer is thin, the amount of the resin composition contained in the resin composition layer is small. Further, in a resin sheet including a support and a resin composition layer, generally, since the flow of the resin composition is restricted by the support in the vicinity of the support of the resin composition layer, the amount of the resin composition that can flow during lamination is even smaller. Therefore, since the fluidity of the resin composition layer during lamination is low, in order to appropriately embed the conductor layer with the resin composition layer, it is required to perform lamination under high-temperature and high-pressure lamination conditions. Among them, when a high-density fine wiring is formed by the conductor layer, particularly high temperature and pressure tend to be required to embed the fine wiring.

[0006] However, when the resin composition layer is as thin as 25 μm or less, the peelability of the support may be poor. Specifically, when peeling the support after curing the resin composition layer to form an insulating layer, peeling failure may occur. To give a specific example, a part of the support may adhere and remain on the insulating layer after peeling the support, or the support may be torn due to a part of the support adhering to the insulating layer in such a manner.

[0007] The present invention was devised in view of the above problems, and aims to provide a method for manufacturing a circuit board capable of peeling a support with good peelability while using a resin sheet having a resin composition layer as thin as 25 μm or less; and a resin sheet capable of performing the method for manufacturing the circuit board.

Means for Solving the Problems

[0008] The present inventor intensively studied to solve the above problems. As a result, the present inventor found that the above problems can be solved when the lamination temperature α between the resin sheet and the inner layer substrate, the lamination pressure β between the resin sheet and the inner layer substrate, and the endothermic peak temperature γ of the release agent of the release layer provided on the support satisfy a specific relationship, and completed the present invention. That is, the present invention includes the following.

[0009] [1] A method for manufacturing a circuit board, using a resin sheet comprising a support having a plastic film layer and a release layer containing a release agent having an endothermic peak temperature by differential scanning calorimetry, and a resin composition layer formed on the support so as to be in contact with the release layer; The manufacturing method comprising: a step of laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are joined; a step of curing the resin composition layer to form an insulating layer, and a step of peeling the support; the thickness of the resin composition layer being 25 μm or less; the lamination temperature α between the resin sheet and the inner layer substrate, the lamination pressure β between the resin sheet and the inner layer substrate, and the endothermic peak temperature γ of the release agent by differential scanning calorimetry satisfying the following formulas (1), (2), and (3): 50°C < γ - α < 135°C (1) 6 kgf / cm 2 < β (2) 120°C ≤ α ≤ 180°C (3) A method for manufacturing a circuit board satisfying the above. [2] The method for manufacturing a circuit board according to [1], wherein the lamination pressure β between the resin sheet and the inner layer substrate is greater than 6 kgf / cm 2 and 20 kgf / cm or less. 2 The method for manufacturing a circuit board according to [1]. [3] The method for manufacturing a circuit board according to [1] or [2], wherein the endothermic peak temperature γ of the release agent by differential scanning calorimetry is 170°C or higher and 270°C or lower. [4] The method for manufacturing a circuit board according to any one of [1] to [3], wherein the release agent contains one or more selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, melamine resins, fluorine resins, acrylic resins, and silicone resins. [5] The method for manufacturing a circuit board according to any one of [1] to [4], wherein the plastic film layer contains one or more selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, and polyamideimide. [6] The manufacturing method of the circuit board according to any one of [1] to [5], wherein the thickness of the support is 5 μm or more and 75 μm or less. [7] The manufacturing method of the circuit board according to any one of [1] to [6], wherein the resin composition layer contains a resin composition containing an epoxy resin, a curing agent, and an inorganic filler. [8] The manufacturing method of the circuit board according to [7], wherein the curing agent contains one or more selected from an active ester resin, a phenolic resin, a cyanate ester resin, and a carbodiimide resin. [9] The manufacturing method of the circuit board according to any one of [1] to [8], including a step of forming holes in the insulating layer.

[10] The manufacturing method of the circuit board according to any one of [1] to [9], including a step of subjecting the insulating layer to desmear treatment.

[11] The manufacturing method of the circuit board according to any one of [1] to

[10] , including a step of forming a conductor layer on the insulating layer.

[12] A resin sheet for use in the manufacturing method of a circuit board, comprising: a support comprising a plastic film layer and a release layer containing a release agent having an endothermic peak temperature by differential scanning calorimetry, and a resin composition layer formed on the support so as to be in contact with the release layer; the thickness of the resin composition layer is 25 μm or less;

[13] The manufacturing method of the circuit board includes: a step of laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are joined; a step of curing the resin composition layer to form an insulating layer, and a step of peeling the support;

[14] The lamination temperature α between the resin sheet and the inner layer substrate, the lamination pressure β between the resin sheet and the inner layer substrate, and the endothermic peak temperature γ of the release agent by differential scanning calorimetry satisfy the following formulas (1), (2), and (3): 50 °C < γ - α < 135 °C (1) 6 kgf / cm 2 < β (2) 120 °C ≤ α ≤ 180 °C (3) A resin sheet satisfying the above conditions.

[13] The resin sheet according to

[12] , comprising a protective film layer for protecting the resin composition layer.

[14] The resin sheet according to

[13] , wherein the protective film layer contains one or more selected from the group consisting of polyethylene, polypropylene, and polyethylene terephthalate. [Advantages of the Invention]

[0010] According to the present invention, there can be provided a method for manufacturing a circuit board, which can peel a support with good peelability while using a resin sheet having a resin composition layer as thin as 25 μm or less; and a resin sheet capable of performing the method for manufacturing the circuit board. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0012] Hereinafter, the present invention will be described with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily modified and implemented without departing from the scope of the claims and their equivalents.

[0013] <Outline of the method for manufacturing a circuit board> In the method for manufacturing a circuit board according to an embodiment of the present invention, a circuit board is manufactured using a resin sheet including a support and a resin composition layer formed on the support. The support of the resin sheet includes a plastic film layer and a release layer. Further, the release layer contains a release agent having an endothermic peak temperature γ by differential scanning calorimetry. Hereinafter, the "endothermic peak temperature by differential scanning calorimetry" may be referred to as the "DSC endothermic peak temperature". And the resin composition layer is formed so as to be in contact with the support.

[0014] This method for manufacturing a circuit board includes a step (I) of laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are joined together, a step (II) of curing the resin composition layer to form an insulating layer, and a step (III) of peeling the support. Normally, steps (I) to (III) are performed in the order of step (I), step (II), and step (III). And in the above step (I), the lamination is performed under lamination conditions that satisfy the following formulas (1), (2), and (3). 50°C < γ - α < 135°C (1) 6 kgf / cm 2 < β (2) 120°C ≤ α ≤ 180°C (3) (In formulas (1), (2), and (3), α represents the lamination temperature between the resin sheet and the inner layer substrate; β represents the lamination pressure between the resin sheet and the inner layer substrate; γ represents the endothermic peak temperature by differential scanning calorimetry of the release agent.)

[0015] According to the above manufacturing method, a circuit board including an inner layer substrate and an insulating layer can be manufactured. And it is possible to improve the peelability of the support. Therefore, for example, it is possible to suppress a part of the support from adhering onto the insulating layer, so that it is possible to suppress a part of the support from remaining on the insulating layer after peeling the support in step (III). Also, for example, it is possible to suppress the support from being torn due to a part of the support adhering onto the insulating layer in such a manner.

[0016] Furthermore, according to the above manufacturing method, usually, the conductor layer (hereinafter sometimes referred to as "substrate conductor layer") provided in the inner layer substrate can be favorably embedded by the resin composition layer. Thus, it is possible to suppress the formation of a gap between the substrate conductor layer and the insulating layer, and it is possible to suppress the formation of voids in the insulating layer due to the gap.

[0017] Although not bound by a specific theory, the inventor conjectures the mechanism by which the above effects are obtained as follows. However, the technical scope of the present invention is not limited by the mechanism described below.

[0018] FIG. 1 is a cross-sectional view schematically showing a state of laminating an inner layer substrate 100 and a conventional resin sheet 900. In the example shown in FIG. 1, the inner layer substrate 100 including a support substrate 110 and a substrate conductor layer 120 formed on a surface 110U of the support substrate 110 is laminated with a resin sheet 900 including a support 910 and a resin composition layer 920. The support 910 includes a plastic film layer 930 formed of a plastic material and a release layer 940 formed of a release agent, and the resin composition layer 920 is provided so as to be in contact with the release layer 940 of the support 910. Further, as shown in FIG. 1, there may be variations in the height of the substrate conductor layer 120 of the inner layer substrate 100 at a minute level. Therefore, some of the substrate conductor layers 121 may be formed relatively higher than the other substrate conductor layers 122. The lamination of these inner layer substrate 100 and resin sheet 900 is usually performed by pressing the inner layer substrate 100 and the resin sheet 900 while applying heat and pressure. When the resin composition layer 920 is thin, the lamination is generally performed under lamination conditions of high temperature and high pressure.

[0019] FIG. 2 is a cross-sectional view schematically showing a state in which the inner layer substrate 100 and the conventional resin sheet 900 are laminated. As shown in FIG. 2, the resin composition layer 920 is softened by the heat applied during lamination and flows by pressure, and can embed the substrate conductor layer 120. At this time, under the conditions of high temperature and high pressure, the release agent forming the release layer 940 is fluidized. Then, following the flow of the resin composition layer 920, the release agent forming the release layer 940 moves, and a portion 900Z may occur where the release layer 940 becomes locally thin or the release layer 940 disappears locally. This portion 900Z may be hereinafter referred to as the "excessive adhesion portion" 900Z. In FIG. 2, an example is shown in which the release agent moves from the portion 900X facing the relatively high substrate conductor layer 121 to the other portion 900Y as indicated by the arrow A1, and the excessive adhesion portion 900Z is formed in the portion 900X, but the position of the excessive adhesion portion 900Z is not limited to the example of FIG. 2. In this excessive adhesion portion 900Z, the resin composition layer 920 and the plastic film layer 930 may come into contact with each other through an excessively thin release layer 940 or may directly contact without passing through the release layer 940, so the adhesion force between the plastic film 930 and the resin composition layer 920 may unintentionally increase.

[0020] After lamination, generally, a step of curing the resin composition layer 920 to form the insulating layer 950 is performed. When the resin composition layer 920 is cured in this way, in the excessive adhesion portion 900Z, the plastic film layer 930 may adhere to the insulating layer 950. In the excessive adhesion portion 900Z where the plastic film layer 930 is adhered to the insulating layer 950 in this way, generally, the plastic film 930 is not easily peeled off from the insulating layer 950.

[0021] FIG. 3 is a cross-sectional view schematically showing a state in which the inner layer substrate 100 and the conventional resin sheet 900 (see FIGS. 1 and 2) are laminated, and the support 910 is peeled off after the resin composition layer 920 is cured. As shown in FIG. 3, when the support 910 is peeled off after the resin composition layer 920 is cured to form the insulating layer 950, in the over-adhesion portion 900Z (see FIG. 2) where the plastic film layer 930 is fixed to the insulating layer 950, a part 931 of the plastic film layer 930 may be chipped and remain on the insulating layer 950. Further, in some cases, the peeling tension for peeling the support 910 may concentrate on the fixed over-adhesion portion 900Z, and the support 910 may be torn starting from the over-adhesion portion 900Z.

[0022] In contrast, in the present embodiment, in step (I), lamination is performed under specific lamination conditions that satisfy formulas (1) to (3). Here, a support having a release layer whose composition is adjusted so as to satisfy formula (1) is used, and an example in which the lamination temperature and the lamination pressure are adjusted so as to satisfy formulas (1), (2), and (3) will be described.

[0023] FIG. 4 is a cross-sectional view schematically showing a state in which the resin sheet 200 according to an example of the present embodiment and the inner layer substrate 100 are laminated. Further, FIG. 5 is a cross-sectional view schematically showing a state in which the resin sheet 200 according to an example of the present embodiment and the inner layer substrate 100 are laminated, and the support 210 is peeled off after the resin composition layer 220 is cured. FIGS. 4 and 5 show an example in which the resin sheet 200 including the support 210 and the resin composition layer 220 is used. In this example, the support 210 includes a plastic film layer 230 formed of a plastic material and a release layer 240 formed of a release agent, and the resin composition layer 220 is provided so as to be in contact with the release layer 240 of the support 210. The inner layer substrate 100 may be the same as described above.

[0024] When laminating under specific lamination conditions that satisfy formulas (1), (2), and (3), the fluidization of the release agent can be suppressed, and thus the movement of the release agent can be suppressed. Therefore, as shown in FIG. 4, it is possible to suppress the generation of a portion where the release layer 240 becomes locally thin or the generation of a portion where the release layer 240 disappears locally. Therefore, even when the resin composition layer 220 is cured to form the insulating layer 250, the adhesion of the plastic film layer 230 to the insulating layer 250 is suppressed. Therefore, as shown in FIG. 5, when the support 210 is peeled off after the formation of the insulating layer 250, it is possible to suppress chipping of the plastic film layer 230 or suppress a part of the plastic film layer from remaining on the insulating layer 250. Further, since the adhesion of the plastic film layer 230 to the insulating layer 250 is suppressed, it is possible to suppress the support 210 from tearing.

[0025] The method for manufacturing a circuit board according to the present embodiment may further include an arbitrary step in combination with the above steps (I) to (III). For example, the method for manufacturing a circuit board may include a step (IV) of forming a hole in the insulating layer, a step (V) of performing a desmear treatment on the insulating layer, and a step (VI) of forming a conductor layer on the insulating layer. These steps (I) to (VI) may be performed in the order of step (I), step (II), step (III), step (IV), step (V), and step (VI).

[0026] <Resin sheet> The resin sheet according to the present embodiment includes a support and a resin composition layer. The support includes a plastic film layer and a release layer. And the resin composition layer is provided so as to be in direct contact with the release layer. Unless otherwise specified, the mode in which two certain layers are in contact is "direct", which means that there is no other layer between these two layers. Hereinafter, each element included in the resin sheet will be described.

[0027] <Support> The support includes a plastic film layer and a release layer formed on the plastic film layer.

[0028] The plastic film layer is a layer formed of a plastic material and thus contains the plastic material. Examples of the plastic material included in the plastic film layer 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"); acrylic polymers such as polymethyl methacrylate (hereinafter sometimes abbreviated as "PMMA"); cyclic polyolefin; triacetyl cellulose (hereinafter sometimes abbreviated as "TAC"); polyethersulfide (hereinafter sometimes abbreviated as "PES"); polyether ketone; polyimide; polyamideimide; and the like. These materials may be used alone or in combination of two or more. Among them, one or more plastic materials selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide and polyamideimide are preferable, polyethylene terephthalate or polyethylene naphthalate is more preferable, and polyethylene terephthalate is particularly preferable.

[0029] The plastic film layer may contain particles that can form fine protrusions to such an extent that slipperiness can be imparted within a range that does not affect the smoothness of the surface of the film layer.

[0030] The surface of the plastic film layer may be subjected to treatments such as matting treatment, corona treatment, antistatic treatment, etc.

[0031] The thickness of the plastic film layer is not particularly limited, but a range of 5 μm to 75 μm is preferable, and a range of 10 μm to 60 μm is more preferable.

[0032] The release layer is a layer formed by a release agent and thus contains the release agent. Preferably, the release layer contains only the release agent. As the release layer, a layer having an effect of reducing the force (peel strength) required for peeling the support can be used. Specifically, due to the action of the release layer, the magnitude of the force required to peel the support in contact with the resin composition layer through the release layer can be reduced compared to the force required to peel the plastic film layer in direct contact with the resin composition layer.

[0033] The release agent for forming the release layer has a DSC endothermic peak temperature (i.e., the endothermic peak temperature by differential scanning calorimetry) γ. The range of this DSC endothermic peak temperature γ is set to satisfy the requirement of formula (1) with respect to the lamination temperature α in step (I). From the viewpoint of satisfying the requirement of formula (1), the DSC endothermic peak temperature γ of the release agent is preferably higher than the DSC endothermic peak temperature γ of a conventional general release agent. The specific range of the DSC endothermic peak temperature γ of the release agent is preferably 170 °C or higher, more preferably 180 °C or higher, still more preferably 190 °C or higher, and preferably 270 °C or lower, more preferably 260 °C or lower, still more preferably 250 °C or lower. When the DSC endothermic peak temperature γ of the release agent is within the above range, the peelability of the support can be made particularly good, and usually, the embeddability of the substrate conductor layer by the resin composition layer can be made particularly good.

[0034] The DSC endothermic peak temperature γ of the release agent can be adjusted, for example, by the composition of the release agent. Specifically, by adjusting the type of resin contained in the release agent or the amount of solvent contained in the release agent, the DSC endothermic peak temperature γ can be adjusted. For example, when a solution of the release agent or its precursor is applied onto the plastic film layer and dried to form the release layer, the DSC endothermic peak temperature γ may be adjusted by adjusting the drying conditions.

[0035] The DSC endothermic peak temperature γ of the release agent can be measured using a differential scanning calorimeter under the conditions of a measurement temperature range of 30 °C to 300 °C and a heating rate of 10 °C / min. As the specific measurement conditions, the method described in the examples below can be adopted.

[0036] As the release agent, for example, a resin can be used. Among them, the release agent preferably contains one or more selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, melamine resins, fluorine resins, acrylic resins, and silicone resins. These resins may be used alone or in combination of two or more. Among them, from the viewpoint of manufacturing a circuit board provided with an insulating layer having excellent insulating properties, a non-silicone resin is preferable, and thus, an alkyd resin, a polyolefin resin, a urethane resin, a melamine resin, a fluorine resin, and an acrylic resin are preferable. Further, an alkyd resin and a polyolefin resin are more preferable, and an alkyd resin is still more preferable.

[0037] If necessary, the release agent may contain a lubricant. Examples of the lubricant include inorganic particles made of inorganic materials such as calcium carbonate, magnesium carbonate, calcium oxide, zinc oxide, magnesium oxide, silicon oxide, sodium silicate, aluminum hydroxide, iron oxide, zirconium oxide, barium sulfate, titanium oxide, tin oxide, antimony trioxide, carbon black, and molybdenum disulfide; organic particles made of organic materials such as acrylic crosslinked polymers, styrene crosslinked polymers, silicone resins, fluorine resins, benzoguanamine resins, phenol resins, nylon resins, and polyethylene waxes; surfactants; and the like.

[0038] The thickness range of the release layer is preferably 0.01 μm or more, more preferably 0.03 μm or more, and still more preferably 0.05 μm or more. When the thickness of the release layer is at least the above lower limit value, the peelability of the support can be made particularly good. Also, the upper limit of the thickness of the release layer is not particularly limited, but from the viewpoint of utilizing the effects of the present invention in a range where conventional problems are likely to occur, it is preferably 2 μm or less, more preferably 1 μm or less, and still more preferably 0.5 μm or less.

[0039] The thickness range of the support is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more, and preferably 75 μm or less, more preferably 60 μm or less, still more preferably 50 μm or less. When the thickness of the support is at least the lower limit value, the generation of wrinkles during lamination can be suppressed. Further, when the thickness of the support is at most the upper limit value, the formation of holes before peeling of the support in step (IV) can be performed with a small amount of energy.

[0040] The support can be produced, for example, by a method including applying a coating liquid for forming a release layer onto a plastic film layer. As the coating liquid, a liquid containing a release agent or a precursor of the release agent can be used. Further, the coating liquid may contain a solvent as necessary. By a method including applying such a coating liquid, a release layer can be formed on the plastic film layer to obtain a support. Further, when a coating liquid containing a solvent is used, the method for forming the release layer may include drying the applied coating liquid after the application of the coating liquid. Further, when the coating liquid contains a precursor of the release agent, the method for forming the release layer may include reacting the precursor to obtain a release agent after the application of the coating liquid. For example, a release agent may be obtained by reacting the precursor by performing a heat treatment after the application of the coating liquid. Further, the method for producing the support may include an optional step such as a stretching step after the formation of the release layer.

[0041] <Resin composition layer> The resin composition layer contains a resin composition and preferably contains only the resin composition. The resin composition contains a curable (A) curable resin. Therefore, an insulating layer can be formed by curing the resin composition layer after laminating the inner layer substrate and the resin sheet.

[0042] The (A) curable resin as the component (A) may be a thermosetting resin, a photocurable resin, or a combination thereof. Further, the (A) curable resin may be used alone or in combination of two or more.

[0043] (A) Examples of the curable resin include epoxy resins, active ester resins, phenolic resins, cyanate ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, and radical polymerizable resins. (A) The curable resin may be used alone or in combination of two or more kinds.

[0044] From the viewpoints of particularly improving the peelability of the support and the embeddability by the resin composition, the chemical resistance in the step of performing desmear treatment, etc., and the adhesion between the insulating layer and the conductor layer, (A) the curable resin preferably contains an epoxy resin, and more preferably contains a combination of an epoxy resin and a resin that can react with and bond to the epoxy resin to cure the resin composition. A resin that can react with and bond to the epoxy resin to cure the resin composition may be hereinafter referred to as a "curing agent". Examples of the curing agent include, for example, active ester resins, phenolic resins, cyanate ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, etc. Among them, the curing agent preferably contains one or more selected from active ester resins, phenolic resins, cyanate ester resins, and carbodiimide resins. The curing agent may be used alone or in combination of two or more kinds.

[0045] An epoxy resin is a curable resin having an epoxy group. Examples of epoxy resins include novolac epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl 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, isocyanurate type epoxy resins, phenolphthalimide type epoxy resins, etc. The epoxy resin may be used alone or in combination of two or more kinds.

[0046] From the viewpoint of obtaining a cured product with excellent heat resistance, the epoxy resin preferably contains an epoxy resin containing an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and includes polycyclic aromatics and aromatic heterocycles. Examples of the epoxy resin containing an aromatic structure include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, biscylenol type epoxy resin, glycidylamine type epoxy resin having an aromatic structure, glycidyl ester type epoxy resin having an aromatic structure, cresol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin having an aromatic structure, epoxy resin having a butadiene structure having an aromatic structure, alicyclic epoxy resin having an aromatic structure, heterocyclic epoxy resin, spiro ring-containing epoxy resin having an aromatic structure, cyclohexanedimethanol type epoxy resin having an aromatic structure, naphthylene ether type epoxy resin, trimethylol type epoxy resin having an aromatic structure, tetraphenylethane type epoxy resin having an aromatic structure, and the like.

[0047] (A) The curable resin preferably contains, as the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule. The ratio 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 with respect to 100% by mass of the non-volatile component of the epoxy resin.

[0048] Epoxy resins include liquid epoxy resins (hereinafter sometimes referred to as "liquid epoxy resins") that are liquid at a temperature of 20°C and solid epoxy resins (hereinafter sometimes referred to as "solid epoxy resins") that are solid at a temperature of 20°C. The resin composition may contain only a liquid epoxy resin as the epoxy resin, or may contain only a solid epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0049] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0050] 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, cyclohexanedimethanol type epoxy resins, and epoxy resins having a butadiene structure.

[0051] Specific examples of the liquid epoxy resin include "HP-4032", "HP-4032-D", "HP-4032-SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", "Epicoat 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolak-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycerol-type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L", "EP-3980S" (glycidylamine-type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (dicyclopentadiene-type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celoxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600", "JP-100", "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658", "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.

[0052] 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.

[0053] Examples of the solid epoxy resin include a vicxylenol type epoxy resin, a naphthalene type epoxy resin, a naphthalene type tetrafunctional epoxy resin, a naphthol novolak type epoxy resin, a cresol novolak type epoxy resin, a dicyclopentadiene type epoxy resin, a trisphenol type epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, a naphthylene ether type epoxy resin, an anthracene type epoxy resin, a bisphenol A type epoxy resin, a bisphenol AF type epoxy resin, a phenol aralkyl type epoxy resin, a tetraphenylethane type epoxy resin, and a phenolphthalimide type epoxy resin.

[0054] Specific examples of the solid epoxy resin include "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", and "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" and "ESN4100V" (naphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YX7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "WHR991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., and the like.These may be used alone or in combination of two or more kinds.

[0055] When using a combination of a liquid epoxy resin and a solid epoxy resin as the epoxy resin, their mass ratio (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0056] The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., still more preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0057] The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight can be measured as a value in terms of polystyrene by the gel permeation chromatography (GPC) method.

[0058] The range of the amount of the epoxy resin is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, based on 100% by mass of the non-volatile components in the resin composition. When the amount of the epoxy resin is within the above range, the peelability of the support can be made particularly good, and further, usually, the embedability of the substrate conductor layer by the resin composition layer can be made particularly good.

[0059] The range of the amount of the epoxy resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 60% by mass or less, based on 100% by mass of the resin component in the resin composition. The resin component in the resin composition represents the component excluding the (B) inorganic filler described later among the non-volatile components in the resin composition. When the amount of the epoxy resin is within the above range, the peelability of the support can be made particularly good, and further, usually, the embeddability of the substrate conductor layer by the resin composition layer can be made particularly good.

[0060] As the active ester resin, a compound having one or more active ester groups in one molecule can be used. Among them, as the active ester resin, compounds having two or more highly reactive ester groups in one molecule, such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc., are preferred. Since the active ester resin can react with the epoxy resin to cure the resin composition when combined with the epoxy resin, it is sometimes referred to as an "active ester curing agent". The active ester resin is preferably obtained by a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. Particularly from the viewpoint of improving heat resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenolic compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc. Examples of the phenolic compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0061] Specifically, as the active ester resin, a dicyclopentadiene type active ester resin, a naphthalene type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolak, and an active ester resin containing a benzoylated product of phenol novolak are preferred, and among them, a naphthalene type active ester resin is more preferred. As the dicyclopentadiene type active ester resin, an active ester resin containing a dicyclopentadiene type diphenol structure is preferred.

[0062] Examples of commercially available active ester resins include, for example, as an active ester resin containing a dicyclopentadiene type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", "HPC-8000H-65TM" (manufactured by DIC Corporation); as an active ester resin containing a naphthalene structure, "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", "EXB-8" (manufactured by DIC Corporation); as a phosphorus-containing active ester resin, "EXB9401" (manufactured by DIC Corporation); as an active ester resin that is an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester resin that is a benzoylated product of phenol novolak, "YLH1026", "YLH1030", "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and as an active ester resin containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Inc.), etc.

[0063] The range of the amount of the active ester resin is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, based on 100% by mass of the non-volatile components in the resin composition. When the amount of the active ester resin is within the above range, the peelability of the support can be made particularly good, and usually, the embedability of the substrate conductor layer by the resin composition layer can also be made particularly good.

[0064] The range of the amount of the active ester resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, based on 100% by mass of the resin components in the resin composition. When the amount of the active ester resin is within the above range, the peelability of the support can be made particularly good, and usually, the embedability of the substrate conductor layer by the resin composition layer can also be made particularly good.

[0065] As the phenolic resin, a compound having one or more, preferably two or more hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring such as a benzene ring or a naphthalene ring in one molecule can be used. Since the phenolic resin can react with the epoxy resin to cure the resin composition when combined with the epoxy resin, it is sometimes referred to as a "phenolic curing agent". From the viewpoints of heat resistance and water resistance, a phenolic resin having a novolak structure is preferred. Also, from the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a phenolic resin containing a triazine skeleton is more preferred. Among them, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion, a phenolic novolak resin containing a triazine skeleton is preferred.

[0066] Specific examples of phenolic resins include "MEH-7700", "MEH-7810", "MEH-7851", "MEH-8000H" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", "SN-375", "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", "TD-2090-60M" manufactured by DIC Corporation; "GDP-6115L", "GDP-6115H", "ELPC75", etc. manufactured by Gun Ei Chemical Industry Co., Ltd.

[0067] As the cyanate ester resin, a compound having one or more, preferably two or more cyanate groups in one molecule can be used. Since the cyanate ester resin can react with an epoxy resin to cure the resin composition when combined with the epoxy resin, it is sometimes referred to as a "cyanate ester curing agent". Examples of the cyanate ester resin include bifunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenebis(phenyl 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 ester resins derived from phenol novolac and cresol novolac; prepolymers in which part of these cyanate ester resins has been triazine-ized; and the like. Specific examples of the cyanate ester resin include "PT30" and "PT60" (phenol novolac type polyfunctional cyanate ester resins), "BA230", "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-ized to form trimers), etc. manufactured by Lonza Japan Co., Ltd.

[0068] As the carbodiimide resin, a compound having one or more, preferably two or more carbodiimide structures in one molecule can be used. Since the carbodiimide resin can react with an epoxy resin to cure the resin composition when combined with the epoxy resin, it is sometimes referred to as a "carbodiimide-based curing agent". Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); biscarbodiimides such as aromatic biscarbodiimides like phenylene-bis(xilylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylene carbodiimide), poly(naphthylene carbodiimide), poly(tolylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), poly(triethylphenylene carbodiimide), poly(diethylphenylene carbodiimide), poly(triisopropylphenylene carbodiimide), poly(diisopropylphenylene carbodiimide), poly(xylylene carbodiimide), poly(tetramethylxylylene carbodiimide), poly(methylenediphenylene carbodiimide), and poly[methylenebis(methylphenylene) carbodiimide]. Commercially available products of the carbodiimide resin include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-05", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemicals Co., Ltd.; "Stabaxol P", "Stabaxol P400", "Highcadil 510", etc. manufactured by Rhein Chemie

[0069] As the acid anhydride resin, a compound having one or more, preferably two or more acid anhydride groups in one molecule can be used. Since the acid anhydride resin can react with an epoxy resin to cure the resin composition when combined with an epoxy group, it is sometimes referred to as an "acid anhydride curing agent". Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfone tetracarboxylic 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 polymer-type acid anhydrides such as styrene-maleic acid resin copolymerized from styrene and maleic acid. Commercially available products of the acid anhydride resin include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", "OSA" manufactured by Shin Nippon Rika Co., Ltd.; "YH-306", "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200", "HN-5500" manufactured by Hitachi Chemical Co., Ltd.; "EF-30", "EF-40", "EF-60", "EF-80" manufactured by Cray Valley Co., Ltd., etc.

[0070] As the amine resin, a compound having one or more, preferably two or more amino groups in one molecule can be used. Since the amine resin can react with an epoxy resin to cure the resin composition when combined with an epoxy group, it is sometimes referred to as an "amine curing agent". Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, aromatic amines are preferred. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 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, 2,2-bis(3-amino-4-hydroxyphenyl)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, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. Commercially available products of the amine resin include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd.; "EPICURE W" manufactured by Mitsubishi Chemical Corporation; "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd., etc.

[0071] As the benzoxazine resin, a compound having one or more, preferably two or more, benzoxazine rings in one molecule can be used. When combined with an epoxy resin, the benzoxazine resin reacts with the epoxy resin to harden the resin composition, and is therefore sometimes called a "benzoxazine curing agent." Specific examples of the benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0072] Thiol-based resins, when combined with epoxy resins, can react with the epoxy resin to harden the resin composition, and are therefore sometimes called "thiol-based hardeners." Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0073] The active group equivalent of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., further preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the resin per equivalent of the active group.

[0074] In one example, the weight average molecular weight (Mw) range of the curing agent may be the same as the weight average molecular weight (Mw) range of the epoxy resin.

[0075] When the epoxy equivalent of the epoxy resin is taken as 1, the active equivalent of the curing agent is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and preferably 3.0 or less, more preferably 2.5 or less, particularly preferably 2.0 or less. The "epoxy equivalent of the epoxy resin" represents the total value obtained by summing up all the values obtained by dividing the mass of the non-volatile component of the epoxy resin present in the resin composition by the epoxy equivalent. The "active equivalent of the curing agent" represents the total value obtained by summing up all the values obtained by dividing the mass of the non-volatile component of the curing agent present in the resin composition by the active equivalent.

[0076] The range of the amount of the curing agent is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, based on 100% by mass of the non-volatile components in the resin composition. When the amount of the curing agent is within the above range, the peelability of the support can be particularly improved, and usually, the embedability of the substrate conductor layer by the resin composition layer can also be particularly improved.

[0077] The range of the amount of the curing agent is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, based on 100% by mass of the resin components in the resin composition. When the amount of the curing agent is within the above range, the peelability of the support can be particularly improved, and usually, the embedability of the substrate conductor layer by the resin composition layer can also be particularly improved.

[0078] As the radical polymerizable resin, a compound having an ethylenically unsaturated bond can be used. Therefore, the radical polymerizable resin may have a radical polymerizable group containing an ethylenically unsaturated bond. Examples of the radical polymerizable group include unsaturated hydrocarbon groups such as vinyl group, allyl group, 1-propenyl group, 3-cyclohexenyl group, 3-cyclopentenyl group, 2-vinylphenyl group, 3-vinylphenyl group, 4-vinylphenyl group; α,β-unsaturated carbonyl groups such as acryloyl group, methacryloyl group, maleimide group (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl group), and the like. The number of radical polymerizable groups contained in one molecule of the radical polymerizable resin may be one, but preferably two or more. The radical polymerizable resin may be used alone or in combination of two or more. Preferred radical polymerizable resins include acrylic resins, styryl resins, allyl resins, and maleimide resins.

[0079] (A) The range of the amount of the curable resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition. When the amount of the curable resin (A) is within the above range, the peelability of the support can be made particularly good, and further, usually, the embedding property of the substrate conductor layer by the resin composition layer can be made particularly good.

[0080] (A) The range of the amount of the curable resin is preferably 40% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, and preferably 99% by mass or less, and may be 95% by mass or less, based on 100% by mass of the resin components in the resin composition. When the amount of the curable resin (A) is within the above range, the peelability of the support can be made particularly good, and further, usually, the embedding property of the substrate conductor layer by the resin composition layer can be made particularly good.

[0081] The resin composition may contain, as an optional component, (B) an inorganic filler. In particular, when the (A) curable resin contains a combination of an epoxy resin and a curing agent, it is preferable that the resin composition further contains (B) an inorganic filler. The (B) inorganic filler as the component (B) does not include those corresponding to the above-mentioned (A) curable resin. The (B) inorganic filler is usually contained in the resin composition in a particulate state.

[0082] (B) As the material of the inorganic filler, an inorganic compound is used. Examples of the material of the (B) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferable, and silica is particularly preferable. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Also, spherical silica is preferable as the silica. The (B) inorganic filler may be used alone or in combination of two or more.

[0083] (B) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", "FB-105FD" manufactured by Denka Co., Ltd.; "Silfill NSS-3N", "Silfill NSS-4N", "Silfill NSS-5N" manufactured by Tokuyama Corporation; "Selfiers", "MGH-005" manufactured by Taiheiyo Cement Corporation; "Esferic", "BA-1" manufactured by JGC Catalysts & Chemicals Ltd., and the like.

[0084] (B) From the viewpoint of significantly obtaining the desired effects of the present invention, the average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less.

[0085] (B) The average particle size of the inorganic filler can be measured by a laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a volume-based particle size distribution of the inorganic filler with a laser diffraction / scattering type particle size distribution measuring device and using the median diameter thereof as the average particle size. As the measurement sample, 100 mg of the inorganic filler and 10 g of methyl ethyl ketone can be weighed into a vial and dispersed by ultrasonic waves for 10 minutes. The measurement sample can be used to measure the volume-based particle size distribution of the inorganic filler using a laser diffraction type particle size distribution measuring device with the wavelengths of the light sources used being blue and red and in a flow cell method, and the average particle size can be calculated as the median diameter from the obtained particle size distribution. Examples of the laser diffraction type particle size distribution measuring device include "LA-960" manufactured by Horiba, Ltd.

[0086] (B) From the viewpoint of significantly obtaining the desired effects of the present invention, the specific surface area of the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5 m 2 / g or more, still more preferably 1 m 2 / g or more, particularly preferably 3 m 2 / g or more, preferably 100 m 2 / g or less, more preferably 70 m 2 / g or less, even more preferably 50 m 2 / g or less, particularly preferably 40 m 2 / g or less. The specific surface area of the inorganic filler can be measured by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method and calculating the specific surface area using the BET multi-point method.

[0087] (B) From the viewpoint of enhancing moisture resistance and dispersibility, the inorganic filler is preferably treated with a surface treatment agent. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, etc. The surface treatment agent may be used alone or in any combination of two or more.

[0088] Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., etc.

[0089] From the perspective of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent preferably falls within a specific range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably surface-treated with 0.2% to 3% by mass of the surface treatment agent, and even more preferably surface-treated with 0.3% to 2% by mass of the surface treatment agent.

[0090] 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 perspective of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg / m 2 or more, more preferably 0.1 mg / m 2 or more, and even more preferably 0.2 mg / m 2 or more. On the other hand, from the perspective of preventing an increase in the melt viscosity of the resin composition, it is preferably 1.0 mg / m 2 or less, more preferably 0.8 mg / m 2 or less, and even more preferably 0.5 mg / m 2 or less.

[0091] (B) The amount of carbon per unit surface area of the inorganic filler can be measured after washing the surface-treated inorganic filler with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler surface-treated with the surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used.

[0092] In addition, the degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit mass of the inorganic filler. The amount of carbon per unit mass of the inorganic filler is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and preferably 1.0% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.5% by mass or less. (B) The amount of carbon per unit mass of the inorganic filler can be measured using a carbon analyzer, similar to the amount of carbon per unit surface area of the inorganic filler.

[0093] (B) The range of the amount of the inorganic filler is preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, based on 100% by mass of the non-volatile components in the resin composition. When the amount of the (B) inorganic filler is within the above range, the peelability of the support can be made particularly good, and usually, the embedding property of the substrate conductor layer by the resin composition layer can be made particularly good.

[0094] The resin composition may contain (C) a curing accelerator as an optional component. The (C) curing accelerator as the (C) component does not include those corresponding to the above-mentioned (A) to (B) components. The (C) curing accelerator can act as a catalyst for the reaction of the (A) thermosetting resin to promote the curing of the resin composition.

[0095] (C) As the curing accelerator, an appropriate one can be used according to the type of the (A) curable resin. For example, when the (A) curable resin contains an epoxy resin, examples of the (C) curing accelerator that can promote the curing of the epoxy resin include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, and the like. The (C) curing accelerator may be used alone or in combination of two or more.

[0096] Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromellitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butyldimethylphosphonium tetraphenylborate; aromatic phosphonium salts such as methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine·triphenylborane; aromatic phosphine-quinone addition reactants such as triphenylphosphine·p-benzoquinone addition reactant; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine;Aromatic phosphines such as dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, 2,2'-bis(diphenylphosphino)diphenylether, etc. can be mentioned.;

[0097] Examples of the urea-based curing accelerators include, for example, 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, 3-cyclooctyl-1,1-dimethylurea; aromatic dimethylureas such as 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, 3-(3,4-dimethylphenyl)-1,1-dimethylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N’,N’-dimethylurea), N,N-(4-methyl-1,3-phenylene)bis(N’,N’-dimethylurea) [toluene bisdimethylurea], and the like.

[0098] Examples of the guanidine-based curing accelerators include, for example, dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide, and the like.

[0099] Examples of imidazole-based curing accelerators include imidazole compounds such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins. Commercially available products of imidazole-based curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "C11Z-A" manufactured by Shikoku Kasei Kogyo Co., Ltd.; "P200-H50" manufactured by Mitsubishi Chemical Corporation, etc.

[0100] Examples of metal-based hardening 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 organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0101] Examples of amine-based hardening accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. As the amine-based hardening accelerator, commercially available products may be used. For example, "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc. etc. can be mentioned.

[0102] (C) The amount range of the hardening accelerator is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.01% by mass or more, and preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, based on 100% by mass of the non-volatile components in the resin composition.

[0103] (C) The amount range of the hardening accelerator is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.02% by mass or more, and preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, based on 100% by mass of the resin components in the resin composition.

[0104] The resin composition may contain, as an optional component, (D) a high molecular resin. The (D) high molecular resin as component (D) does not include those corresponding to the above-mentioned components (A) to (C). The (D) high molecular resin is usually compatible with resin components other than the (D) high molecular resin and is contained in the resin composition and its cured product. The (D) high molecular resin may be used alone or in combination of two or more kinds.

[0105] Examples of the (D) high molecular resin include, for example, phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. Among them, phenoxy resin is preferred.

[0106] Examples of the phenoxy resin include, for example, phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, novolak skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of the phenoxy resin include "1256" and "4250" (both bisphenol A skeleton-containing phenoxy resins) manufactured by Mitsubishi Chemical Corporation; "YX8100" (bisphenol S skeleton-containing phenoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX6954" (bisphenol acetophenone skeleton-containing phenoxy resin) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL7500BH30", "YL6954BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation; etc.

[0107] Specific examples of the polyimide resin include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., "Lica Coat SN20" and "Lica Coat PN20" manufactured by Nippon Rika Kagaku Co., Ltd., and the like.

[0108] Examples of the polyvinyl acetal resin include, for example, polyvinyl formal resin and polyvinyl butyral resin, and polyvinyl butyral resin is preferred. Specific examples of the polyvinyl acetal resin include "Denka Butyral 4000-2", "Denka Butyral 5000-A", "Denka Butyral 6000-C", "Denka Butyral 6000-EP" manufactured by Denki Kagaku Kogyo Co., Ltd.; the Esrec BH series, BX series (for example, BX-5Z), KS series (for example, KS-1), BL series, BM series manufactured by Sekisui Chemical Co., Ltd.; and the like.

[0109] Examples of the polyolefin resin include ethylene-based copolymer resins such as low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin polymers such as polypropylene and ethylene-propylene block copolymer, and the like.

[0110] Examples of the polybutadiene resin include, for example, a resin containing a hydrogenated polybutadiene skeleton, a hydroxy group-containing polybutadiene resin, a phenolic hydroxyl group-containing polybutadiene resin, a carboxy group-containing polybutadiene resin, an acid anhydride group-containing polybutadiene resin, an epoxy group-containing polybutadiene resin, an isocyanate group-containing polybutadiene resin, a urethane group-containing polybutadiene resin, a polyphenylene ether-polybutadiene resin, and the like.

[0111] Specific examples of the polyamideimide resin include "Vylon Max HR11NN" and "Vylon Max HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin also include modified polyamideimides such as "KS9100" and "KS9300" (polyamideimide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

[0112] Specific examples of the polyetherimide resin include "Ultem" manufactured by GE Corporation.

[0113] Specific examples of the polysulfone resin include polysulfones "P1700", "P3500", etc. manufactured by Solvay Advanced Polymers, LLC.

[0114] Specific examples of the polyethersulfone resin include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0115] Specific examples of the polyphenylene ether resin include "NORYL SA90" manufactured by SABIC.

[0116] Examples of the polycarbonate resin include a hydroxy group-containing carbonate resin, a phenolic hydroxyl group-containing carbonate resin, a carboxy group-containing carbonate resin, an acid anhydride group-containing carbonate resin, an isocyanate group-containing carbonate resin, a urethane group-containing carbonate resin, etc. Specific examples of the polycarbonate resin include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "T6002", "T6001" (polycarbonate diol) manufactured by Asahi Kasei Chemicals Corporation, "C-1090", "C-2090", "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd., etc.

[0117] Specific examples of the polyetheretherketone resin include "Sumipro EK" manufactured by Sumitomo Chemical Co., Ltd.

[0118] Examples of the polyester resin include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, polycyclohexanedimethyl terephthalate resin, and the like.

[0119] (D) The polymer resin usually has a large molecular weight. Specifically, the range of the weight average molecular weight Mw of the (D) polymer resin is preferably greater than 5000, more preferably 8000 or more, still more preferably 10000 or more, particularly preferably 20000 or more, and preferably 100000 or less, more preferably 70000 or less, still more preferably 60000 or less, particularly preferably 50000 or less.

[0120] (D) The range of the amount of the polymer resin is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 1% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, based on 100% by mass of the non-volatile components of the resin composition.

[0121] (D) The range of the amount of the polymer resin is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, based on 100% by mass of the resin components of the resin composition.

[0122] The resin composition may further contain (E) an optional additive as an optional component. The (E) optional additive as component (E) does not include those corresponding to the above-described components (A) to (D). Examples of the (E) optional additive include radical polymerization initiators such as peroxide-based radical polymerization initiators and azo-based radical polymerization initiators; organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as benton and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic-based flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers. The (E) optional additive may be used alone or in combination of two or more.

[0123] The resin composition may further contain (F) a solvent as an optional volatile component in combination with the non-volatile components such as the above-described components (A) to (E). Usually, an organic solvent is used as the (F) solvent. Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; ether ester solvents such as 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The (F) solvent may be used alone or in combination of two or more.

[0124] (F) The amount of the solvent is not particularly limited. However, when the total components in the resin composition are 100% by mass, for example, it can be 20% by mass or less, 10% by mass or less, 5% by mass or less, etc., and it may be 0% by mass.

[0125] The resin composition preferably has a low minimum melt viscosity. The range of the minimum melt viscosity of the resin composition is preferably 10,000 poise or less, more preferably 9,000 poise or less, and still more preferably 7,000 poise or less. According to the resin composition layer containing the resin composition having such a low minimum melt viscosity, the substrate conductor layer provided in the inner layer substrate can be favorably embedded by the resin composition layer. The lower limit of the minimum melt viscosity is preferably 200 poise or more, more preferably 500 poise or more, from the viewpoint of smoothly forming a resin composition layer having a desired thickness. The minimum melt viscosity of the resin composition can be measured using a dynamic viscoelasticity measuring device. Specifically, the temperature is raised under the conditions of a temperature rising rate of 5°C / min in the temperature range from the starting temperature of 60°C to 200°C, and the dynamic viscoelastic modulus of the sample is measured under the conditions of a measurement temperature interval of 2.5°C, a frequency of 1 Hz, and a strain of 1 deg to obtain the minimum melt viscosity.

[0126] By curing the resin composition layer, an insulating layer containing a cured product of the resin composition can be formed. During the above-mentioned curing, usually, heat is applied to the resin composition layer, so among the components contained in the resin composition, volatile components such as (F) solvents can be volatilized by the heat during curing. Therefore, the cured product of the resin composition may contain non-volatile components of the resin composition or reaction products thereof.

[0127] The above-mentioned cured product can usually have a low dielectric tangent, so the insulating layer containing the cured product can have a low dielectric tangent. In one example, the dielectric tangent of the insulating layer is preferably 0.030 or less, more preferably 0.020 or less, and still more preferably 0.010 or less. There is no particular limitation on the lower limit, and it can be, for example, 0.0001 or more. The dielectric tangent of the insulating layer can be measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by the cavity resonance perturbation method. When the sample is the resin composition layer before curing, the resin composition layer is cured under the curing conditions of 180°C for 60 minutes to obtain an insulating layer, and the dielectric tangent of the insulating layer can be measured.

[0128] The thickness of the resin composition layer is usually 25 μm or less, more preferably 23 μm or less, and still more preferably 20 μm or less. Conventionally, in a resin sheet having a resin composition layer with such a small thickness, the problem of poor peeling of the support has specifically occurred. In the present embodiment, the above-mentioned problem in a resin sheet having a resin composition layer with a thickness in such a range can be solved. The lower limit of the thickness of the resin composition layer is preferably 3 μm or more, more preferably 4 μm or more, and still more preferably 5 μm or more.

[0129] The thickness Y of the resin composition layer may be larger, smaller, or the same as the height X of the substrate conductor layer of the inner layer substrate. Generally, when the substrate conductor layer becomes denser, the amount of the resin composition required to fill the substrate conductor layer decreases. Therefore, even when using a resin composition layer with a thickness Y thinner than the height X of the substrate conductor layer, it is possible to satisfactorily embed the substrate wiring layer with the resin composition layer.

[0130] Among them, it is preferable that the thickness Y of the resin composition layer has a specific relationship with the height X of the substrate conductor layer of the inner layer substrate to which the resin composition layer is joined. Specifically, the range of the ratio Y / X of the thickness Y of the resin composition layer to the height X of the substrate conductor layer is preferably 1.4 or less, more preferably 1.3 or less, and still more preferably 1.2 or less, and is preferably 0.3 or more, more preferably 0.4 or more, and still more preferably 0.5 or more. In a configuration where the ratio Y / X is equal to or less than the above upper limit value, conventionally, the problem of poor peeling of the support has been particularly likely to occur. However, even in a configuration where such peeling failure is likely to occur, according to the manufacturing method according to the present embodiment, the peeling failure can be suppressed and good peelability can be achieved. From the viewpoint of effectively utilizing this effect, it is preferable that the ratio Y / X is equal to or less than the above upper limit value. On the other hand, when the ratio Y / X is equal to or more than the above lower limit value, the embedding property of the substrate conductor layer by the resin composition layer can be particularly improved.

[0131] On the surface of the inner layer substrate laminated with the resin composition layer, the height of the substrate conductor layer may be non-uniform. In this case, it is preferable that the requirement regarding the ratio Y / X is satisfied, taking the height of at least a part of the substrate conductor layer as "the height X of the substrate conductor layer". Further, it is more preferable that the requirement regarding the ratio Y / X is satisfied, taking the average height of the substrate conductor layer as "the height X of the substrate conductor layer". The average height of the substrate conductor layer can be measured by forming a cross-section of the inner layer substrate, polishing the cross-section, and then measuring the height of the substrate conductor layer at a plurality of points with a microscope such as a scanning electron microscope (SEM), and calculating the average.

[0132] <Any layer that the resin sheet may include> The resin sheet may be provided with an arbitrary layer in combination with the support and the resin composition layer. For example, the resin sheet may be provided with a protective film layer that protects the resin composition layer as an arbitrary layer. The protective film layer is usually provided on the surface that is not joined to the support of the resin composition layer (that is, the surface opposite to the support). According to the protective film layer, the adhesion of dust to the resin composition layer and the scratches on the resin composition layer can be suppressed.

[0133] As the protective film layer, for example, a film layer containing a plastic material can be used. As the plastic material contained in the protective film layer, for example, the same plastic material as that contained in the plastic film layer of the support may be used. Among them, polyesters such as polyethylene terephthalate and polyethylene naphthalate; and polyolefins such as polyethylene and polypropylene are preferable. Further, it is more preferable that the plastic material contains one or more selected from the group consisting of polyethylene, polypropylene, and polyethylene terephthalate. The plastic material may be used alone or in combination of two or more.

[0134] The thickness of the protective film layer is not particularly limited and may be, for example, 1 μm to 40 μm. Usually, after the protective film layer is peeled off, the resin sheet is subjected to lamination in step (I).

[0135] <Method for manufacturing resin sheet> The resin sheet can be manufactured, for example, by a method including preparing a resin composition and applying the resin composition onto a release layer of a support. When using a liquid (varnish-like) resin composition, the resin composition may be directly applied onto the release layer of the support. Alternatively, a liquid (varnish-like) resin composition may be prepared by mixing a solvent and a non-volatile component of the resin composition, and then applied onto the release layer. Examples of the solvent include the same solvents as the (F) solvents described as components of the resin composition.

[0136] The resin composition can be manufactured, for example, by mixing components that can be included in the resin composition. The above-described components may be mixed partially or entirely simultaneously, or may be mixed in sequence. During the process of mixing each component, the temperature may be appropriately set, and thus, heating and / or cooling may be performed temporarily or throughout the process. Further, stirring or shaking may be performed during the process of mixing each component.

[0137] The application of the resin composition can be performed, for example, using an appropriate coating device such as a die coater.

[0138] The method for manufacturing a resin sheet may include a step of drying the applied resin composition after the application of the resin composition. For example, when the resin composition contains a solvent, the solvent can be removed by drying. Drying may be performed by a drying method such as heating or hot air blowing. The drying conditions are not particularly limited, but the resin composition is dried so that the content of the solvent in the resin composition layer falls within a desired range. Although it varies depending on the boiling point of the solvent in the resin composition, for example, when using a resin composition containing 30% to 60% by mass of the solvent, a resin composition layer may be formed by drying at 50°C to 150°C for 3 minutes to 10 minutes.

[0139] The method for manufacturing a resin sheet may include a step of forming a protective film layer on the resin composition layer after the formation of the resin composition layer. For example, the protective film layer can be formed by laminating the protective film layer on the resin composition layer. Further, the resin sheet may be wound into a roll and stored as needed. As described above, when the resin sheet has a protective film, it is usually made usable by peeling off the protective film.

[0140] <Step (I). Lamination of the resin sheet and the inner layer substrate> The method for manufacturing a circuit board according to this embodiment includes a step (I) of laminating a resin sheet and an inner layer substrate. The lamination of the resin sheet and the inner layer substrate is performed such that the resin composition layer of the resin sheet and the inner layer substrate are joined. By this lamination, a resin composition layer is formed on the inner layer substrate. And the substrate conductor layer of the inner layer substrate is embedded by the resin composition layer.

[0141] The inner layer substrate to be laminated with the resin sheet is a member that serves as a base material of the circuit board, and usually includes a support substrate 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. This support substrate may include a circuit inside thereof and may incorporate components.

[0142] Usually, the circuit board includes a substrate conductor layer formed on one or both sides of the support substrate. This substrate conductor layer may be pattern-processed. For example, the substrate conductor layer may be pattern-processed to form a wiring having a desired pattern. The "pattern" of the wiring represents the shape of the wiring as viewed from the thickness direction, unless otherwise specified.

[0143] The range of the minimum line / space ratio of the substrate conductor layer is preferably 200 μm / 200 μm or less (i.e., the pitch is 400 μm or less), more preferably 180 μm / 180 μm or less, and even more preferably 150 μm / 150 μm or less. The lower limit can be, for example, 0.5 μm / 0.5 μm or more. The pitch may be uniform or non-uniform over the entire substrate conductor layer. The range of the minimum pitch of the substrate conductor layer may be, for example, 400 μm or less, 360 μm or less, or 300 μm or less. Here, "line" represents the wiring width of the substrate conductor layer, and "space" represents the interval between wirings.

[0144] The range of the height X of the substrate conductor layer is preferably 20 μm or less, and can be 18 μm or less, 16 μm or less, etc. When laminating an inner layer substrate having such a substrate conductor layer with a resin sheet provided with a thin resin composition layer as described above, conventionally, problems of peeling failure were likely to occur. Therefore, from the viewpoint of effectively utilizing the effect of this embodiment that can solve problems that could not be solved conventionally, the height X of the substrate conductor layer is preferably equal to or less than the above upper limit value. Also, the lower limit of the range of the height X of the substrate conductor layer is preferably 5 μm or more, and can be 7 μm or more, 9 μm or more, etc.

[0145] The height of the substrate conductor layer may be uniform or non-uniform. When the height of the substrate conductor layer is non-uniform, it is preferable that the height of at least a part of the substrate conductor layer falls within the above range. Furthermore, it is more preferable that the average height of the substrate conductor layer falls within the above range. Among them, it is even more preferable that the overall height of the substrate conductor layer falls within the above range.

[0146] The substrate conductor layer can be formed of the same conductor material as the conductor layer formed on the insulating layer in step (VI). The method for forming the substrate conductor layer is not particularly limited, and for example, it may be formed by the same method as the method for forming the conductor layer in step (VI).

[0147] When manufacturing a circuit board, an intermediate product on which an insulating layer and / or a conductor layer should be further formed is also included in the above "inner layer substrate".

[0148] The lamination of the inner layer substrate and the resin sheet can be performed, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of the member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as "thermocompression bonding member") include a heated metal plate (such as a SUS mirror plate) or a metal roll (SUS roll). Note that, rather than pressing the thermocompression bonding member directly against the resin sheet, it is preferable to press through an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently follow the surface unevenness of the inner layer substrate.

[0149] The lamination temperature α of the inner layer substrate and the resin sheet is set such that the difference "γ - α" between the DSC endothermic peak temperature γ of the release agent and the lamination temperature α satisfies the above formula (1). Specifically, the range of the difference "γ - α" is usually greater than 50°C, preferably 51°C or higher, more preferably 52°C or higher, and usually less than 135°C, preferably 130°C or lower, more preferably 120°C or lower.

[0150] Also, the lamination temperature α is set within a range that satisfies the above formula (3). The specific range of the lamination temperature α is usually 120°C or higher, preferably 130°C or higher, more preferably 140°C or higher, and usually 180°C or lower, preferably 175°C or lower, more preferably 170°C or lower.

[0151] Furthermore, the lamination pressure β of the inner layer substrate and the resin sheet is set to satisfy formula (2). Specifically, the range of the lamination pressure β is usually greater than 6 kgf / cm 2 more preferably greater than 7 kgf / cm 2 or higher, more preferably 8 kgf / cm 2 or higher, still more preferably 9 kgf / cm 2 or higher, and preferably 20 kgf / cm 2 or lower, more preferably 18 kgf / cm 2 or lower, still more preferably 16 kgf / cm 2 or lower.

[0152] When the difference “γ - α” between the DSC endothermic peak temperature γ of the release agent and the lamination temperature α, the lamination temperature α, and the lamination pressure β are within the above ranges, the peelability of the support can be improved, and usually, the embedability of the substrate conductor layer by the resin composition layer can also be improved.

[0153] The time for lamination (lamination time) at the above-described lamination temperature α and lamination pressure β can be set within a range in which the substrate conductor layer can be embedded by the resin composition layer. The specific range of the lamination time is preferably 20 seconds or more, more preferably 30 seconds or more, preferably 400 seconds or less, and more preferably 300 seconds or less.

[0154] The lamination of the inner layer substrate and the resin sheet is preferably carried out by a vacuum lamination method. In the vacuum lamination method, lamination is carried out under reduced pressure conditions. Specifically, the pressure in the vacuum lamination method is preferably 26.7 hPa or less.

[0155] Lamination can be carried out using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure type laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichco Materials Co., Ltd., a batch type vacuum pressure laminator, and the like.

[0156] In the method for manufacturing a circuit board according to the present embodiment, after the lamination of the inner layer substrate and the resin sheet, under normal pressure (atmospheric pressure), for example, by pressing a heat - crimping member from the support side, a smoothing process of the resin sheet may be performed. The smoothing process is usually performed before step (II). The press conditions for the smoothing process can be the same as the lamination conditions of the above lamination (specifically, the lamination temperature α and the lamination pressure β). The smoothing process can be carried out using a commercially available laminator. Note that lamination and the smoothing process may be continuously carried out using the above - mentioned commercially available vacuum laminator.

[0157] <Step (II). Curing of the resin composition layer> The manufacturing method of the circuit board according to this embodiment includes step (II) of curing the resin composition layer after step (I). By curing the resin composition layer in step (II), an insulating layer can be formed. The insulating layer includes a cured product of the resin composition, and preferably includes only the cured product of the resin composition.

[0158] The curing of the resin composition layer can be performed by a method suitable for the resin composition, such as thermal curing or photocuring. Specific curing conditions for the resin composition layer may use the conditions usually adopted when forming the insulating layer of the circuit board.

[0159] When a thermosetting resin composition is used, the curing of the resin composition can proceed as thermal curing. Therefore, in this case, step (II) may include thermally curing the resin composition layer. The thermal curing conditions of the resin composition layer may also vary depending on the type of the resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. Also, the curing time can be preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0160] In addition, when thermally curing the resin composition layer, the manufacturing method of the circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before the thermal curing. For example, prior to thermally curing the resin composition layer, the resin composition layer is usually preheated at a temperature of 50°C to 150°C, preferably 60°C to 140°C, more preferably 70°C to 130°C for usually 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. The preheating is usually performed after step (I). Also, when a smoothing process is performed after the lamination of the inner layer substrate and the resin sheet, the preheating can be performed after the smoothing process.

[0161] On the other hand, when a photocurable resin composition is used, the curing of the resin composition can proceed as photocuring. Therefore, in this case, step (II) may include photocuring the resin composition layer. The photocuring conditions of the resin composition may vary depending on the type of the resin composition. For example, the resin composition layer in the irradiated portion can be photocured by an exposure treatment in which the resin composition layer is irradiated with actinic rays. Examples of the actinic rays include ultraviolet rays, visible light, electron beams, X-rays, etc., and ultraviolet rays are particularly preferable. The irradiation amount of ultraviolet rays is, for example, 10 mJ / cm 2 ~1000 mJ / cm 2 . In the exposure treatment, the resin composition layer may be irradiated with actinic rays through a mask on which a pattern is formed.

[0162] When the resin composition layer is photocured, after photocuring, a post-bake treatment may be performed as necessary. Examples of the post-bake treatment include an ultraviolet irradiation treatment using a high-pressure mercury lamp, a heat treatment using a clean oven, etc. The ultraviolet irradiation treatment can be performed, for example, with an irradiation amount of about 0.05 J / cm 2 ~10 J / cm 2 . Also, the heat treatment can be performed, for example, preferably in the range of 150°C to 250°C for 20 minutes to 180 minutes, more preferably in the range of 160°C to 230°C for 30 minutes to 120 minutes.

[0163] <Step (III). Peeling of the support> The method for manufacturing a circuit board according to the present embodiment includes a step (III) of peeling the support after step (I). Usually, by peeling the support, the support can be peeled smoothly. Depending on the lamination in step (I) described above, the adhesion of the plastic film layer of the support to the insulating layer is suppressed, so the peelability of the support is enhanced. Therefore, it is possible to suppress a part of the support remaining on the insulating layer after peeling of the support or the support being torn by peeling, and thus smooth peeling of the support can be achieved.

[0164] Generally, the support is peeled off by pulling the support relative to the insulating layer. For example, with the support fixed, the insulating layer and the inner layer substrate may be conveyed and the support may be peeled off. Also, for example, with the insulating layer and the inner layer substrate fixed, the support may be pulled to peel off the support. Further, for example, while pulling the support, the insulating layer and the inner layer substrate may be conveyed to peel off the support.

[0165] Normally, the support is relatively pulled in a peeling direction that forms a specific angle with respect to the surface of the insulating layer, and the peeling of the support is achieved. There is no particular limitation on the range of the angle formed by the peeling direction with respect to the surface of the insulating layer. The peeling direction may be, for example, parallel to the surface of the inner layer substrate, perpendicular to it, or in other directions.

[0166] The temperature conditions for peeling the support are not particularly limited. From the viewpoint of reducing the energy required for manufacturing the circuit board, generally, the peeling of the support is performed at room temperature or a temperature close thereto.

[0167] In the method for manufacturing a circuit board according to this embodiment, since peeling failure between the insulating layer and the support is suppressed, it is possible to increase the peeling speed of the support. From the viewpoint of contributing to an improvement in the production speed of the circuit board, it is preferable that the peeling speed is high. The specific range of the peeling speed is preferably 1 m / min or more, more preferably 2 m / min or more, still more preferably 3 m / min or more, still more preferably 4 m / min or more, and particularly preferably 5 m / min or more. The upper limit is not particularly limited and may be, for example, 20 m / min or less, 10 m / min or less, etc.

[0168] <Step (IV). Formation of holes> The manufacturing method of the circuit board according to this embodiment may include a step (IV) of forming holes such as via holes and through holes in the insulating layer. The formation of the holes may be performed before step (III) or after step (III). The method for forming the holes can be selected according to factors such as the composition of the resin composition used for forming the insulating layer. For example, holes may be formed by processing methods such as drilling, laser processing, and plasma processing, and among them, laser processing is preferred. For example, after peeling the support, the insulating layer may be irradiated with laser light to form holes, or the insulating layer may be irradiated with laser light through the support to form holes. The dimensions and shapes of the holes may be appropriately determined according to the design of the circuit board.

[0169] <Step (V). Desmear treatment> The manufacturing method of the circuit board according to this embodiment may include a step (V) of performing a desmear treatment on the insulating layer. According to the desmear treatment, smears (resin residues) can be removed from the insulating layer. For example, when holes are formed in step (IV), smears may be formed in the holes, so it is preferable to perform a desmear treatment in step (V) to remove the above-mentioned smears. Also, depending on the desmear treatment, roughening of the surface of the insulating layer may progress, so this desmear treatment may be called a "roughening treatment".

[0170] Step (V) is usually performed after step (IV). The procedures and conditions of the desmear treatment are not particularly limited, and known procedures and conditions commonly used when forming the insulating layer of the circuit board can be adopted. For example, a swelling treatment with a swelling solution, an oxidation treatment with an oxidizing agent, and a neutralization treatment with a neutralizing solution can be sequentially performed on the insulating layer to perform the desmear treatment.

[0171] Examples of the swelling liquid used for the desmear treatment include, for example, an alkaline solution, a surfactant solution, etc., and an alkaline solution is preferred. As the alkaline solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferred. Examples of commercially available swelling liquids include, for example, "Swelling Dip Security P" and "Swelling Dip Security SBU" manufactured by Atotech Japan Co., Ltd. The swelling treatment with the swelling liquid can be carried out, for example, by immersing the insulating layer in the swelling liquid at 30°C to 90°C for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin of the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in the swelling liquid at 40°C to 80°C for 5 minutes to 15 minutes.

[0172] Examples of the oxidizing agent used for the desmear treatment include, for example, an alkaline permanganate solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The oxidation treatment with an oxidizing agent such as an alkaline permanganate solution is preferably carried out by immersing the insulating layer in the oxidizing agent solution heated to 60°C to 100°C for 10 minutes to 30 minutes. Further, the concentration of the permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include, for example, alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Security P" manufactured by Atotech Japan Co., Ltd.

[0173] As the neutralizing liquid used for the desmear treatment, an acidic aqueous solution is preferred, and examples of commercially available products include, for example, "Reduction Solution Securant P" manufactured by Atotech Japan Co., Ltd. The neutralization treatment with the neutralizing liquid can be carried out by immersing the treated surface that has been subjected to the oxidation treatment with the oxidizing agent in the neutralizing liquid at 30°C to 80°C for 5 minutes to 30 minutes. From the viewpoint of workability and the like, a method of immersing the object that has been subjected to the oxidation treatment with the oxidizing agent in the neutralizing liquid at 40°C to 70°C for 5 minutes to 20 minutes is preferred.

[0174] <Step (VI). Formation of the conductor layer> The method for manufacturing a circuit board according to this embodiment may include a step (VI) of forming a conductor layer on an insulating layer. When the method for manufacturing a circuit board includes steps (IV) and (V), the step (VI) of forming a conductor layer is usually performed after steps (IV) and (V).

[0175] The conductor 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 the alloy layer include layers formed from alloys of two or more metals selected from the above group (for example, nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among them, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., a single-metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy is preferable, a single-metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy is more preferable, and a single-metal layer of copper is even more preferable.

[0176] The conductor layer may have a single-layer structure, or may have a multilayer structure in which two or more single-metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multilayer structure, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of nickel-chromium alloy.

[0177] When patterning the conductor layer, the range of the minimum line / space ratio of the conductor layer may be the same as the range of the minimum line / space ratio of the substrate conductor layer of the circuit board. Further, the range of the minimum pitch of the conductor layer formed on the conductor layer may be the same as the range of the minimum pitch of the substrate conductor layer of the circuit board. The pitch may be uniform or non-uniform over the entire conductor layer.

[0178] The thickness range of the conductor layer depends on the design of the desired circuit board, and may be the same as the height range of the substrate conductor layer of the circuit board.

[0179] In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating on the surface of the insulating layer by a conventionally known technique such as a semi-additive method or a full-additive method. From the viewpoint of manufacturing simplicity, the semi-additive method is preferred. Hereinafter, an example of forming the conductor layer by the semi-additive method will be shown.

[0180] First, an electroless plating layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plating layer to expose a part of the electroless plating layer corresponding to the desired wiring pattern. After forming an electrolytic plating layer by electrolytic plating on the exposed electroless plating layer, the mask pattern is removed. Thereafter, the unnecessary electroless plating layer can be removed by etching or the like to form a conductor layer having a desired wiring pattern.

[0181] <Other matters related to the manufacturing method> In the manufacturing method of the circuit board according to the present embodiment, each of the above-described steps may be performed only once, or may be repeated two or more times. For example, steps (I) to (VI) may be repeatedly performed to form a circuit board having a multilayer structure such as a multilayer printed wiring board including a plurality of insulating layers and conductor layers.

[0182] The manufacturing method of the circuit board according to the present embodiment may further include any arbitrary steps in combination with the above-described steps. For example, the method for manufacturing a circuit board according to this embodiment may include a step of providing a semiconductor chip so as to be joined to a conductor layer. To give a specific example, when manufacturing a circuit board for a semiconductor chip package including a semiconductor chip, the method for manufacturing the circuit board may include a step of providing the semiconductor chip. The semiconductor chip can adopt appropriate conditions under which the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer can be conductively connected. For example, the conditions used in flip chip mounting can be adopted. Further, the semiconductor chip may be joined via an insulating adhesive or may be joined by reflow. Furthermore, if necessary, the provided semiconductor chip may be filled with a mold underfill material. In addition, the method for manufacturing a circuit board according to this embodiment may include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, a step of dicing the manufactured circuit board into individual pieces, and the like.

[0183] <Circuit board to be manufactured> According to the manufacturing method described above, a circuit board including an inner layer substrate and an insulating layer can be manufactured. In the manufacturing method described above, since the support can be peeled off with good peelability, it is possible to suppress a part of the support from sticking and remaining on the surface of the insulating layer. Further, in this circuit board, the substrate conductor layer of the inner layer substrate is embedded in the insulating layer. In the manufacturing method described above, since the substrate conductor layer by the resin composition layer can be well embedded, it is possible to suppress the formation of voids in the insulating layer. Further, according to the manufacturing method described above, preferably, a circuit board including an inner layer substrate, an insulating layer, and a conductor layer in this order can be manufactured.

[0184] Examples of such a circuit board include a printed wiring board and a semiconductor chip package. Examples of the semiconductor chip package include an FC-CSP, a MIS-BGA package, an ETS-BGA package, a Fan-out type WLP (Wafer Level Package), a Fan-in type WLP, a Fan-out type PLP (Panel Level Package), and a Fan-in type PLP. In these semiconductor chip packages, it is preferable to form a redistribution layer formation layer with an insulating layer obtained by curing the above-described resin composition layer. However, the circuit board manufactured by the manufacturing method according to the present embodiment is not limited to those exemplified here.

[0185] The above circuit board can be used in the manufacture of semiconductor devices. The semiconductor layer includes the above-described circuit board. Examples of the semiconductor device include various semiconductor devices used in electrical products (such as computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical devices, and televisions) and vehicles (such as motorcycles, automobiles, trains, ships, and airplanes).

Example

[0186] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass%", respectively, unless otherwise specified. Also, the temperature conditions and pressure conditions in the absence of special designation were room temperature (25°C) and atmospheric pressure (1 atm). Furthermore, in the following description, "L / S" represents the line / space ratio unless otherwise specified.

[0187] <Production Example 1. Production of Support A> 100 parts of a coating agent "FS-9200L" (manufactured by Nippon Chemical Coatings Co., Ltd.) and 4 parts of a curing agent "FS curing agent" (manufactured by Nippon Chemical Coatings Co., Ltd.) for the coating agent were mixed to produce a release agent liquid as a coating liquid. This release agent liquid was applied onto a PET film (Toray Industries, Inc.'s "Lumirror R80", thickness 38 μm, softening point 130 °C) as a plastic film layer, and dried at 150 °C for 30 seconds to form a release layer with a thickness of 1 μm containing an alkyd resin as a release agent. Through the above operations, a support A comprising a PET film and a release layer was obtained. The DSC endothermic peak temperature of the release agent forming the release layer of support A was 250 °C.

[0188] <Production Example 2. Production of Support B> A support B comprising a PET film and a release layer (thickness 1 μm) was obtained in the same manner as in Production Example 1, except that the drying condition after applying the release agent liquid onto the PET film was changed to 150 °C for 10 seconds. The DSC endothermic peak temperature of the release agent forming the release layer of support B was 192 °C.

[0189] <Production Example 3. Production of Support C> A support C comprising a PET film and a release layer (thickness 1 μm) was obtained in the same manner as in Production Example 1, except that the drying condition after applying the release agent liquid onto the PET film was changed to 130 °C for 30 seconds. The DSC endothermic peak temperature of the release agent forming the release layer of support C was 165 °C.

[0190] <Production Example 4. Production of Support D> A support D comprising a PET film and a release layer (thickness 1 μm) was obtained in the same manner as in Production Example 1, except that the drying condition after applying the release agent liquid onto the PET film was changed to 100 °C for 30 seconds. The DSC endothermic peak temperature of the release agent forming the release layer of support D was 141 °C.

[0191] <Production Example 5. Production of Support E> The release agent liquid "HZ-523" (manufactured by Takamatsu Oil & Fat Co., Ltd.) was applied onto a PET film (Toray Industries, Inc.'s "Lumirror R80", thickness 38 μm, softening point 130 °C) as a plastic film layer, and dried at 120 °C for 3 minutes to form a release layer with a thickness of 1 μm containing a polyolefin resin as a release agent. Through the above operations, a support E comprising a PET film and a release layer was obtained. The DSC endothermic peak temperature of the release agent forming the release layer of the support E was 100 °C.

[0192] <Measurement of the DSC Endothermic Peak Temperature of the Release Agent> In the above-described Production Examples 1 to 5, the DSC endothermic peak temperature of the release agent forming the release layer was measured by the following method. The release agent liquid was applied onto a release substrate such as Teflon (registered trademark) by a coating method such as spin coating, and dried under the same conditions as each production example to form a release agent film. This release agent film was peeled off from the substrate to obtain a release agent sample composed of the release agent alone. The obtained release agent sample was measured with a differential scanning calorimeter (Hitachi's "DSC7000X") under the conditions of 30 °C to 300 °C (heating rate 10 °C / min) to obtain the DSC endothermic peak temperature.

[0193] The information on the supports produced in Production Examples 1 to 5 is summarized in Table 1 below.

[0194]

Table 1

[0195] <Example 1> (Production of the Resin Varnish) 15 parts of liquid bisphenol A type epoxy resin (epoxy equivalent 180 g / eq., "828US" manufactured by Mitsubishi Chemical Corporation) and 15 parts of biphenyl type epoxy resin (epoxy equivalent 291 g / eq., "NC3000H" manufactured by Nippon Kayaku Co., Ltd.) were heated and dissolved with stirring in 15 parts of methyl ethyl ketone (hereinafter abbreviated as "MEK") and 15 parts of cyclohexanone to obtain a solution. To this solution, 43 parts of a naphthalene type active ester compound ("HPC8000-65T" manufactured by DIC Corporation, active ester equivalent 272 g / eq., toluene solution with a solid content of 65%), 0.15 part of a curing accelerator (4-dimethylaminopyridine manufactured by Koei Chemical Industry Co., Ltd.), 100 parts of spherical silica (average particle size 0.5 μm, specific surface area 5.8 m 2 / g, "SO-C2" treated with phenylaminosilane, manufactured by Admatechs Co., Ltd., carbon amount per unit mass 0.18%), and 15 parts of phenoxy resin ("YL6954BH30" manufactured by Mitsubishi Chemical Corporation, MEK solution with a solid content of 30% by mass, weight average molecular weight 40,000) were mixed and uniformly dispersed with a high-speed rotary mixer to produce a resin varnish.

[0196] (Manufacture of resin sheet) On the release layer of the support A manufactured in Production Example 1, the resin varnish was uniformly applied with a die coater so that the thickness of the dried resin composition layer would be 15 μm, and dried at 80°C to 110°C (average 95°C) for 3 minutes to obtain a resin sheet.

[0197] (Lamination and curing) A dummy pattern substrate including a support substrate and a copper layer (thickness 15 μm) formed on the surface of the support substrate was prepared. The copper layer had a comb tooth pattern with L / S = 150 μm / 150 μm formed thereon. The dummy pattern substrate and the resin sheet were laminated so that the copper layer and the resin composition layer would be joined. The above lamination was carried out by heat pressing under the conditions of a lamination temperature α = 140°C, a lamination pressure β = 10 kgf / cm 2 2, and a lamination time of 120 seconds. Thereafter, the resin composition layer was thermally cured at 180°C for 60 minutes. By the thermal curing of the resin composition layer, an insulating layer was formed, and a sample substrate corresponding to a circuit board was obtained.

[0198] (Test 1. Peelability Evaluation Test) The end of the support was pulled at a speed of 5 m / min in a direction 90° to the surface of the inner layer substrate to peel the support from the sample substrate, and visually, (1) whether there was no PET residue on the surface of the insulating layer, and (2) whether the support was not torn, were confirmed. The above-mentioned PET residue corresponds to a resin residue formed by a part of the support adhering to the insulating layer and remaining. The above operation was performed on 5 sample substrates. When no PET residue or tear of the support was confirmed in any of the 5 sample substrates, the peelability was judged as "〇". Also, when PET residue or tear of the support was confirmed in one or more sample substrates, the peelability was judged as "×".

[0199] (Test 2. Embeddability Evaluation Test) The part where the comb tooth pattern of the copper layer of the sample substrate was formed was observed at 50 times magnification using a microscope ("VHX-5000" manufactured by Keyence Corporation), and it was confirmed whether voids (bubbles) were formed. The above operation was performed on 5 sample substrates. When no voids were confirmed in any of the 5 sample substrates, the embeddability was judged as "〇". Also, when voids were confirmed in one or more sample substrates, the embeddability was judged as "×".

[0200] <Examples 2 to 13 and Comparative Examples 1 to 20> Except that the type of the support, the thickness of the resin composition layer of the resin sheet after drying, the height of the copper layer of the dummy pattern substrate, the lamination temperature α, and the lamination pressure β were changed as shown in the following table, the sample substrates corresponding to the circuit boards were manufactured and evaluated by the same method as in Example 1.

[0201] <Results> The results of the above-described examples and comparative examples are shown in the following table. In the following table, the meanings of the abbreviations are as follows. PET cracking: The number of sample substrates in which cracking of the support was confirmed in the peelability evaluation test. In this column, the denominator number "5" represents the total number of sample substrates subjected to the peelability evaluation test, and the numerator number represents the number of sample substrates in which cracking of the support was confirmed. PET residue: The number of sample substrates in which residues of PET remaining on the surface of the insulating layer were confirmed in the peelability evaluation test. In this column, the denominator number "5" represents the total number of sample substrates subjected to the peelability evaluation test, and the numerator number represents the number of sample substrates in which residues of PET were confirmed. Void: The number of sample substrates in which voids were confirmed in the embedability evaluation test. In this column, the denominator number "5" represents the total number of sample substrates subjected to the embedability evaluation test, and the numerator number represents the number of sample substrates in which voids were confirmed.

[0202]

Table 2

[0203]

Table 3

[0204]

Table 4

[0205]

Table 5

Explanation of Symbols

[0206] 100 Inner layer substrate 110 Support substrate 110U Surface of the support substrate 120, 121, 122 Substrate conductor layer 200 Resin sheet 210 Support 220 Resin composition layer 230 Plastic film layer 240 Release layer 250 insulating layer

Claims

1. A method for manufacturing a circuit board, using a resin sheet comprising a support provided with a plastic film layer and a release layer containing a release agent having an endothermic peak temperature by differential scanning calorimetry, and a resin composition layer formed on the support so as to be in contact with the release layer; wherein the manufacturing method comprises: a step of laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are joined; a step of curing the resin composition layer to form an insulating layer; and a step of peeling the support; the thickness of the resin composition layer is 25 μm or less; the lamination temperature α between the resin sheet and the inner layer substrate, the lamination pressure β between the resin sheet and the inner layer substrate, and the endothermic peak temperature γ of the release agent by differential scanning calorimetry satisfy the following formulas (1), (2) and (3): 50°C < γ - α < 135°C (1) 6 kgf / cm ２ <β (2) １２０℃≦α≦１８０℃ （３） A method for manufacturing a circuit board that satisfies the above conditions.

2. The lamination pressure β between the resin sheet and the inner layer substrate is greater than 6 kgf / cm ２ and not more than 20 kgf / cm ２ The method for manufacturing a circuit board according to claim 1, wherein the method is as described above.

3. The method for manufacturing a circuit board according to Claim 1, wherein the endothermic peak temperature γ of the release agent by differential scanning calorimetry is 170°C or higher and 270°C or lower.

4. The method for manufacturing a circuit board according to Claim 1, wherein the release agent contains one or more selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, melamine resins, fluorine resins, acrylic resins, and silicone resins.

5. The method for manufacturing a circuit board according to Claim 1, wherein the plastic film layer contains one or more selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, and polyamideimide.

6. The method for manufacturing a circuit board according to Claim 1, wherein the thickness of the support is 5 μm or more and 75 μm or less.

7. The method for manufacturing a circuit board according to Claim 1, wherein the resin composition layer contains a resin composition containing an epoxy resin, a curing agent, and an inorganic filler.

8. The method for manufacturing a circuit board according to Claim 7, wherein the curing agent contains one or more selected from the group consisting of active ester resins, phenolic resins, cyanate ester resins, and carbodiimide resins.

9. The method for manufacturing a circuit board according to Claim 1, further comprising a step of forming holes in the insulating layer.

10. The method for manufacturing a circuit board according to Claim 1, further comprising a step of subjecting the insulating layer to desmear treatment.

11. The method for manufacturing a circuit board according to Claim 1, further comprising a step of forming a conductor layer on the insulating layer.

12. A resin sheet for use in a method for manufacturing a circuit board; The resin sheet includes a support having a plastic film layer and a release layer containing a release agent having an endothermic peak temperature by differential scanning calorimetry, and a resin composition layer formed on the support so as to be in contact with the release layer; The thickness of the resin composition layer is 25 μm or less; The method for manufacturing the circuit board is a step of laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are joined, a step of curing the resin composition layer to form an insulating layer, and a step of peeling the support; The lamination temperature α between the resin sheet and the inner layer substrate, the lamination pressure β between the resin sheet and the inner layer substrate, and the endothermic peak temperature γ of the release agent by differential scanning calorimetry satisfy the following formulas (1), (2) and (3): 50°C < γ - α < 135°C (1) 6 kgf / cm ２ <β (2) １２０℃≦α≦１８０℃ （３） A resin sheet that satisfies the above.

13. The resin sheet according to claim 12, further comprising a protective film layer for protecting the resin composition layer.

14. The resin sheet according to claim 13, wherein the protective film layer contains one or more selected from the group consisting of polyethylene, polypropylene, and polyethylene terephthalate.

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