Resin composition, and resin film, resin-coated metal foil, metal-clad laminate, and wiring board using the same

Abstract

One aspect of the present invention relates to a resin composition comprising an acrylic resin and a curing agent. The acrylic resin comprises a polymerization unit (A) of a (meth)acrylate having an epoxy group, a polymerization unit (B) of a (meth)acrylate having a cyano group, and a polymerization unit (C) of a (meth)acrylate having an isobornyl group. The weight average molecular weight of the acrylic resin is 50,000-3,000,000 inclusive. The storage modulus of a cured product of the acrylic resin at 200°C is 0.1 MPa to 3.5 MPa inclusive.

Description

[Technical Field]

[0001] The present invention relates to a resin composition, particularly a resin composition that has stretchability in its cured form, and to a resin film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that use the same. [Background technology]

[0002] In the electronics field, there is a growing demand for wearability and shape-following capabilities for devices and substrate materials used in various interfaces, such as sensors, displays, and artificial skin for robots. There is a growing demand for flexible devices and materials that can be placed on curved or uneven surfaces and can be freely deformed depending on the application.

[0003] In response to such demands, various flexible (stretchable) resin substrates have been investigated.

[0004] For example, Patent Document 1 discloses an elastic resin substrate containing a rubber component and a crosslinking component. Patent Document 2 also reports that an epoxy resin, which is a reaction product of an epoxy compound and an acid-terminated polyester, has excellent flexibility.

[0005] However, although the elastic resin substrate described in Patent Document 1 is thought to have elasticity, it contains a non-reactive rubber component and is therefore thought to have problems such as poor heat resistance and solvent resistance.

[0006] Furthermore, although the epoxy resin described in the above-mentioned document 2 has excellent flexibility, the epoxy equivalent of the epoxy resin used is small, so that the curing shrinkage is large and there is a risk of warpage deformation in substrates using this resin. Furthermore, the weather resistance is also thought to be insufficient.

[0007] Furthermore, resin materials used as substrate materials are required to have excellent adhesion to metal layers or metal foils when used in metal-clad laminates or wiring boards. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2018 / 123818 [Patent Document 2] International Publication No. 2018 / 216752 Summary of the Invention

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition which has excellent resin flow properties, and in the cured product thereof, has excellent flexibility, heat resistance, tear strength, and adhesion, and further has excellent dimensional stability due to the ability to suppress cure shrinkage, as well as a resin film, a laminate, a wiring board, and the like which use the same.

[0010] As a result of extensive research, the present inventors have found that the above problems can be solved by a resin composition and / or resin film having the following configuration, and have completed the present invention through further research based on this finding.

[0011] That is, a resin composition according to one aspect of the present invention comprises an acrylic resin and a curing agent, wherein the acrylic resin comprises polymerized units (A) of a (meth)acrylate having an epoxy group, polymerized units (B) of a (meth)acrylate having a cyano group, and polymerized units (C) of a (meth)acrylate having an isobornyl group; the weight-average molecular weight of the acrylic resin is 50,000 or more and 3,000,000 or less; and the storage modulus of the cured product at 200°C is 0.1 MPa or more and 3.5 MPa or less. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing the evaluation criteria for embeddability in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to these.

[0014] As described above, the resin composition of this embodiment contains at least an acrylic resin and a curing agent. The acrylic resin contains polymerized units (A) of a (meth)acrylate having an epoxy group, polymerized units (B) of a (meth)acrylate having a cyano group, and polymerized units (C) of a (meth)acrylate having an isobornyl group. The weight-average molecular weight of the acrylic resin contained in the resin composition is 50,000 to 3,000,000. The resin composition of this embodiment has a cured product with a storage modulus of 0.1 MPa to 3.5 MPa at 200°C.

[0015] Due to this configuration, the resin composition of this embodiment has excellent flexibility, heat resistance, tear strength, and adhesion in its cured product. Furthermore, since cure shrinkage can be suppressed, the resin composition has excellent dimensional stability, and has the advantage of being less likely to deform (warp) even after curing. Furthermore, the resin composition of this embodiment also has excellent resin flow properties, and exhibits excellent advantages when used as a resin film for metal-clad laminates and wiring boards.

[0016] The resin composition of this embodiment has a storage modulus of 0.1 MPa or more and 3.5 MPa or less in its cured product. When the storage modulus is within the above range, the resin composition can have heat resistance in its cured product. In this embodiment, "storage modulus" refers to the storage modulus at 200°C, and is a value measured by the method described in the Examples below. From the viewpoint of exhibiting better heat resistance, the storage modulus is preferably 0.1 MPa or more and 2.5 MPa or less, and more preferably 0.3 MPa or more and 2.0 MPa or less.

[0017] As described above, the resin composition of the present embodiment has excellent heat resistance in the cured product, and also has the advantage that a reflow process can be used in the mounting process of electronic components.

[0018] In a preferred embodiment, the resin composition of this embodiment has a glass transition temperature (Tg) of 60° or less in the cured product. This is believed to ensure that the cured product has flexibility. The glass transition temperature is more preferably 40° C. or less. Although there is no particular need to set a lower limit, from the viewpoint of preventing stickiness of the film surface at room temperature when made into a resin film, the glass transition temperature is preferably 20° C. or more.

[0019] In this embodiment, "flexible" means that the elongation rate to break of a cured product of the resin composition is 5.0% or more, preferably 10% or more, more preferably 25% or more, even more preferably 50%, and most preferably 100% or more. Furthermore, this means that the tensile modulus of a cured product of the resin composition of this embodiment at room temperature of 25°C is 0.1 MPa or more and 0.5 GPa or less, preferably 1 MPa or more and 300 MPa or less, and more preferably 5 MPa or more and 100 MPa or less. The values ​​of "elongation rate to break" and "tensile modulus at room temperature of 25°C" in this embodiment are values ​​measured by the methods described in the Examples below.

[0020] On the other hand, there is no particular need to set an upper limit for the flexibility, but from the viewpoint that excessive stretching will damage the original shape, it is preferable that the elongation percentage does not exceed 500%. In the examples, the index (elongation percentage) showing flexibility in this embodiment is shown as breaking elongation percentage [%].

[0021] Furthermore, the resin composition of this embodiment has the advantage that the cured product thereof has excellent tear strength and is less likely to break even when stretched.

[0022] The resin composition of the present embodiment has excellent adhesion in the cured product, and when used in a metal laminate, has the advantage of high adhesion between the metal foil and the substrate. Furthermore, the resin composition of the present embodiment has excellent resin flow properties, so it is also advantageous for use in wiring boards where narrow wiring is formed.

[0023] First, each component contained in the resin composition of this embodiment will be described. In this embodiment, the resin composition refers to a composition before curing (uncured or semi-cured). That is, the epoxy groups in the polymerization units (A) described below are in an uncrosslinked state.

[0024] (acrylic resin) The resin composition of this embodiment contains an acrylic resin as a main component. The acrylic resin here refers to a polymer compound obtained by polymerizing a compound having one or more acryloyl or methacryloyl groups. In this embodiment, the acrylic resin serves as a binder and imparts flexibility to a cured product of the composition.

[0025] The acrylic resin has a weight average molecular weight of 50,000 or more and 3,000,000 or less, and contains polymerized units (A) of a (meth)acrylate having an epoxy group, polymerized units (B) of a (meth)acrylate having a cyano group, and polymerized units (C) of a (meth)acrylate having an isobornyl group.

[0026] By ensuring that the weight-average molecular weight of the acrylic resin used in this embodiment is within the above range, it is possible to obtain a cured resin product and a resin film that are excellent in flexibility (stretchability), tensile strength (break resistance), and resin flowability. The lower limit of the weight-average molecular weight is more preferably 100,000 or more, and even more preferably 200,000 or more. Meanwhile, the upper limit is more preferably 2,000,000 or less, and even more preferably 1,000,000 or less.

[0027] The acrylic resin of this embodiment preferably does not have unsaturated bonds such as double bonds or triple bonds between carbon atoms. That is, the carbon atoms of the acrylic resin are preferably bonded to each other by saturated bonds (single bonds). It is believed that the absence of unsaturated bonds between carbon atoms prevents oxidation over time and allows the resin to maintain better elasticity.

[0028] The acrylic resin of this embodiment is not an acrylic resin obtained by polymerizing only the polymerization unit (A), only the polymerization unit (B), or only the polymerization unit (C), but is a resin obtained by randomly polymerizing the polymerization units (A), (B), and (C). The form of polymerization is not particularly limited, and may be a block copolymer, an alternating copolymer, a random copolymer, a graft copolymer, or the like.

[0029] Polymerized units of (meth)acrylate having an epoxy group (A) In this embodiment, the acrylic resin contains polymerized units (A) of a (meth)acrylate having an epoxy group. The polymerized units (A) provide crosslinking points to the acrylic resin of this embodiment, making it curable. Furthermore, it is believed that the presence of epoxy groups in the acrylic resin improves the heat resistance of the cured product after heat curing.

[0030] The content of the polymerized units (A) in the acrylic resin is not particularly limited, but it is preferable that the epoxy equivalent relative to the total amount of the acrylic resin is approximately 1000 g / eq or more and 8000 g / eq or less. It is believed that an epoxy equivalent in this range more reliably produces a resin composition having heat resistance and a moderate elastic modulus. If the epoxy equivalent is less than 1000 g / eq, the elastic modulus after curing may be too high, resulting in breakage during elongation. Furthermore, if the epoxy equivalent exceeds 8000 g / eq, the elastic modulus after curing at high temperatures may be low, which may cause deformation of the film during, for example, a reflow process, resulting in mounting defects. A more preferable range for the epoxy equivalent is 1500 g / eq or more and 5000 g / eq or less.

[0031] Specific examples of the (meth)acrylate monomer constituting the polymerized unit (A) having an epoxy group include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, β-ethylglycidyl (meth)acrylate, glycidyl vinyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, o-isopropenylbenzyl glycidyl ether, m-isopropenylbenzyl glycidyl ether, p-isopropenylbenzyl glycidyl ether, etc. These may be used alone or in combination of two or more.

[0032] Polymerized units of (meth)acrylate having a cyano group (B) In this embodiment, the acrylic resin contains a polymerization component (B) of a (meth)acrylate having a nitrile group. By including a (meth)acrylate having a cyano group, hydrogen bonding with the metal foil surface occurs, resulting in excellent adhesion when the resin composition or resin film of this embodiment is used in a metal-clad laminate. Furthermore, the presence of the polymerization unit (B) is thought to provide sufficient tear strength and further improve heat resistance.

[0033] Specific examples of the (meth)acrylate monomer constituting the polymerized unit (B) having a cyano group are not particularly limited, but include, for example, acrylonitrile and methacrylonitrile.

[0034] The acrylic resin used in the resin composition of this embodiment preferably has a polydispersity (Mw / Mn) of the average molecular weight of the acrylic resin that satisfies the following formula (1).

[0035] 1.1≦Mw / Mn≦3.0 (1) In the formula (1), Mn is the number average molecular weight, and Mw is the weight average molecular weight.

[0036] It is believed that if the polydispersity of the average molecular weight of the acrylic resin is within the above range, it is possible to obtain a resin composition having sufficient breaking strength in the cured product.

[0037] The resin composition of this embodiment preferably contains the polymerized unit (B) component in an amount of 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the acrylic resin. It is believed that a content within this range can more reliably achieve the above-mentioned effects. If the content of the polymerized unit (B) component is lower than this range, there is a risk of deterioration in adhesion to the copper foil. Furthermore, if the content exceeds the above range, there is a risk of the elastic modulus increasing and the stretchability becoming poor, which is undesirable. A more preferred content of the polymerized unit (B) component is 10 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the acrylic resin.

[0038] Polymerized units of (meth)acrylate having an isobornyl group (C) In this embodiment, the acrylic resin further contains (meth)acrylate polymerization units (C) having an isobornyl group. The inclusion of this polymerization unit (C) component having an isobornyl group can suppress the increase in cure shrinkage, and in turn, can suppress deformation such as warping when the resin composition or resin film is cured.

[0039] Specific examples of the acrylate or (meth)acrylate monomer constituting the polymerized unit (C) having an isobornyl group include, but are not particularly limited to, isobornyl (meth)acrylate.

[0040] The resin composition of this embodiment preferably contains the polymerized unit (C) component in an amount of 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the acrylic resin. It is believed that a content within this range can more reliably achieve the above-mentioned effects. If the content of the polymerized unit (C) component is lower than this range, dimensional stability may be impaired. Furthermore, if the content exceeds the above range, the reactivity of the polymerized unit (A) of the (meth)acrylate having an epoxy group decreases, resulting in poor heat resistance of the resin composition after heat curing, which is undesirable. Furthermore, the viscosity of the resin composition increases, which is undesirable from the viewpoint of printability. A more preferred content of the polymerized unit (C) component is 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the acrylic resin.

[0041] Polymerization units other than those mentioned above The acrylic resin of the present embodiment may contain other polymer units in addition to the above-mentioned polymer units (A), (B), and (C).

[0042] Specific examples of the other polymerized units include acrylic monomers represented by the following formula (1) (hereinafter also referred to as polymerized units (D)).

[0043] [ka]

[0044] In the formula (1), R1 is hydrogen or a methyl group, R2 is hydrogen or an alkyl group, and X is an integer.

[0045] The acrylic monomer represented by the formula (1) preferably has a low glass transition temperature (Tg) in order to impart flexibility to the resin composition of this embodiment.

[0046] Specific examples of the acrylic monomer represented by the formula (1) include ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.

[0047] The blending ratio of the acrylic resin in the resin composition of this embodiment is not particularly limited as long as it is within a range in which the effects of the present invention, such as flexibility and adhesion, can be obtained, but it is preferably, for example, about 50 to 70 mass % of the entire resin composition.

[0048] Furthermore, the resin composition of the present embodiment may contain a resin other than the acrylic resin, and an epoxy resin, a urethane resin, an acrylic resin, a fluororesin, a silicone resin, or the like may also be added depending on the purpose.

[0049] (hardening agent) The resin composition of this embodiment further contains a curing agent. The curing agent that can be used in this embodiment is not particularly limited as long as it functions as an epoxy curing agent. Specific examples include phenolic resins, amine-based compounds, acid anhydrides, imidazole-based compounds, sulfide resins, dicyandiamide, mercapto-based compounds, onium salts, and peroxides. Light / ultraviolet curing agents and thermal cationic curing agents can also be used. Depending on the circumstances, one type of these may be used alone, or two or more types may be used in combination. Preferably, the curing agent of this embodiment contains at least one selected from acid anhydrides, amine-based curing agents, phenol-based curing agents, and carboxylic acid-based curing agents.

[0050] Among these, it is preferable to use an acid anhydride as the curing agent, and examples of acid anhydride curing agents include maleic anhydride, succinic anhydride, itaconic anhydride, citraconic anhydride, phthalic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, and methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride.

[0051] Preferably, the curing agent of this embodiment contains a polyfunctional acid anhydride having two or more functionalities. This has the advantage of causing three-dimensional crosslinking and suppressing deformation, especially at high temperatures. It also reduces shrinkage during curing.

[0052] As the difunctional or higher polyfunctional acid anhydride, commercially available products can be used, such as Rikacid BT-100, TDA-100, and TBN-100 (all manufactured by New Japan Chemical Co., Ltd.), and ENEHYDE CpODA (manufactured by JXTG Nippon Oil & Energy Corporation).

[0053] When the curing agent contains the polyfunctional acid anhydride, the acid anhydride equivalent of the curing agent of this embodiment is preferably 100 g / eq or more and 500 g / eq or less. This is believed to more reliably achieve the above-mentioned effects. A more preferred acid anhydride equivalent is 300 g / eq or more and 500 g / eq or less.

[0054] In the resin composition of this embodiment, the amount of the curing agent added can be appropriately set according to the epoxy equivalent.

[0055] Furthermore, the resin composition according to the present embodiment may contain other additives, such as a curing accelerator (curing catalyst), a surfactant, a flame retardant, a flame retardant assistant, a leveling agent, a colorant, an ultraviolet absorber, an infrared absorber, an antistatic agent, a conductive assistant, inorganic fine particles, and the like, as needed, within a range that does not impair the effects of the present invention.

[0056] (curing accelerator) The curing accelerator usable in this embodiment is not particularly limited, but examples thereof include imidazoles and derivatives thereof, organophosphorus compounds, metal soaps such as zinc octanoate, secondary amines, tertiary amines, quaternary ammonium salts, etc. Depending on the circumstances, one of these may be used alone, or two or more may be used in combination.

[0057] When a curing accelerator is used, the content thereof is preferably 0.01 to 1 mass % relative to 100 mass parts of the resin composition.

[0058] (surfactant) The resin composition of the present embodiment may contain a surfactant to improve wettability with a substrate during film production. Usable surfactants include various surfactants such as nonionic, cationic, and anionic surfactants.

[0059] When a surfactant is used, the content thereof is preferably 0.01 to 1.5% by mass relative to 100 parts by mass of the resin composition.

[0060] (Preparation of Resin Composition and Resin Film) The method for preparing the resin composition containing the acrylic resin of this embodiment is not particularly limited. For example, the acrylic resin, curing agent, and solvent are mixed uniformly. The solvent used is not particularly limited. For example, toluene, xylene, methyl ethyl ketone, acetone, etc. can be used. These solvents may be used alone or in combination of two or more. Furthermore, here, an organic solvent for adjusting viscosity and various additives may be added as needed.

[0061] The resin film of the present embodiment can be obtained by heating and drying the resin composition obtained as described above to evaporate the solvent. That is, the present embodiment also includes a resin film formed using the resin composition described above.

[0062] The method, apparatus, and conditions for heat-drying the resin composition may be the same as those of the conventional methods or improved methods. The specific heating temperature and time can be appropriately set depending on the curing agent, solvent, etc. used, but the resin composition can be made into a resin film by, for example, heat-drying at 130 to 200°C for about 60 to 180 minutes.

[0063] The resin film of this embodiment may be composed solely of the resin composition or a semi-cured product thereof, or may be in the form of a resin-coated film having a resin layer containing the resin composition or a semi-cured product thereof and a support (support film). That is, this embodiment also encompasses a resin sheet material comprising the resin film and a support layer overlying the resin film. Examples of the support include electrically insulating films such as polyimide film, PET (polyethylene terephthalate) film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, aramid film, polycarbonate film, and polyarylate film.

[0064] The resin-coated film (resin sheet material) of this embodiment may be a resin-coated film comprising the resin composition before curing (uncured) (the resin composition in A stage) and a support, or may be a resin-coated film comprising a semi-cured product of the resin composition (the resin composition in B stage) and a support.

[0065] As a method for producing such a resin-coated film, for example, a resin composition in the form of a resin varnish as described above is applied to the surface of a film support substrate, and then the solvent is evaporated from the varnish to reduce or remove the solvent, thereby obtaining a resin-coated film in a pre-cured (A stage) or semi-cured (B stage) state.

[0066] In the resin-coated film of this embodiment, the resin composition or the semi-cured product thereof may be obtained by drying or heat-drying the resin composition.

[0067] In this embodiment, the term "semi-cured product" refers to a resin composition that has been partially cured to the extent that it can be further cured. That is, the semi-cured product is a resin composition that has been semi-cured (B-staged). For example, when a resin composition is heated, the viscosity initially gradually decreases, and then curing begins, and the viscosity gradually increases. In such a case, the semi-cured state can be exemplified by the state between when the viscosity starts to increase and when the composition is completely cured.

[0068] Furthermore, the resin film of this embodiment also includes a cured resin film obtained by curing a resin-coated film in the pre-cured state (A stage) or semi-cured state (B stage) as described above.

[0069] (Applications of resin film) The resin film of the present embodiment can be used in a variety of applications as a material or substrate for various electronic components, etc. In particular, because it has excellent flexibility and strength, as well as adhesion, resin flowability, and dimensional stability, it is extremely suitable as a material for, for example, foldable electronic paper, organic EL displays, solar cells, RFID, pressure sensors, wearable devices, skin patch devices, etc.

[0070] (resin-coated metal foil, metal-clad laminate, and wiring board) Next, a resin-coated metal foil, a metal-clad laminate, a wiring board, and the like using the resin composition and / or resin film of this embodiment will be described.

[0071] The resin-coated metal foil of this embodiment has a resin layer containing the above-mentioned resin film and a metal foil overlying the resin layer. That is, it has a configuration in which the metal foil is laminated on at least one side of the resin layer. The metal foil may be on both sides of the resin layer. The resin-coated metal foil of this embodiment may be a resin-coated metal foil comprising a resin layer containing the resin composition before curing (the resin composition in A stage) and a metal foil, or a resin-coated metal foil comprising a resin layer containing a semi-cured product of the resin composition (the resin composition in B stage) and a metal foil.

[0072] Examples of methods for producing such resin-coated metal foils include coating the resin composition in the form of a resin varnish as described above onto the surface of a metal foil such as a copper foil, followed by drying. Examples of the coating method include a bar coater, a comma coater, a die coater, a roll coater, a gravure coater, and the like.

[0073] As the metal foil, any metal foil used in metal-clad laminates, wiring boards, etc. can be used without any limitation, and examples thereof include copper foil and aluminum foil.

[0074] The thickness of the metal foil or film support substrate can be appropriately set depending on the desired purpose.

[0075] There are no particular limitations on the drying or heat-drying conditions in the manufacturing method of resin-coated metal foil or resin-coated film, but after applying a resin composition in the form of a resin varnish to the above-mentioned metal foil or film support substrate, it is heated and dried under the same conditions as those for the above-mentioned resin film, and the solvent is volatilized from the varnish, thereby reducing or removing the solvent, thereby obtaining a resin-coated metal foil or resin-coated film in an uncured (A stage) or semi-cured (B stage) state.

[0076] The resin-coated metal foil or resin-coated film may be provided with a cover film or the like as necessary. The provision of a cover film can prevent the inclusion of foreign matter, etc. The cover film is not particularly limited as long as it can be peeled off without damaging the shape of the resin composition. For example, a polyolefin film, a polyester film, a TPX film, a film formed by providing a release agent layer on any of these films, or even paper formed by laminating any of these films onto a paper substrate can be used.

[0077] The metal-clad laminate of the present embodiment has an insulating layer containing the cured product of the resin composition described above and a metal foil overlying the insulating layer. Note that the metal foil used in the metal-clad laminate can be the same as the metal foil described above.

[0078] Furthermore, the metal-clad laminate of this embodiment can be produced by, for example, stacking one or more of the resin films, and then stacking a metal foil such as copper foil on either or both of the upper and lower surfaces of the stack, and then heat-pressing and molding the stack to form an integrated laminate. The heat-pressing conditions can be appropriately set depending on the thickness of the laminate to be produced, the type of resin composition, and the like, but can be, for example, a temperature of 150 to 220°C, a pressure of 1.5 to 5.0 MPa, and a time of 60 to 180 minutes.

[0079] The wiring board of this embodiment includes an insulating layer containing the resin film or the cured product of the resin composition, and wiring, the wiring being provided on at least one selected from the surface and the interior of the insulating layer.

[0080] The resin composition and resin film of this embodiment are suitable for use as materials for insulating layers of wiring boards. For example, a wiring board can be produced by etching the metal foil on the surface of the metal clad laminate obtained above to form a circuit (wiring), thereby obtaining a wiring board having a conductor pattern (wiring) as a circuit on the surface of the laminate. Examples of the circuit formation method include, in addition to the above-described methods, circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0081] The resin-coated metal foil, metal-clad laminate, and wiring board obtained using the resin composition and resin film of this embodiment are highly useful for industrial applications because they have excellent flexibility, heat resistance, and strength (tensile strength), as well as adhesion, resin flowability, and dimensional stability.

[0082] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. [Example]

[0083] First, the various materials used in this example are as follows:

[0084] (Acrylic Resin 1) Acrylonitrile was used as the polymerized unit (B), isobornyl acrylate as the polymerized unit (C), and polymerized unit (D) represented by the following formula (1) were used in the blending ratios (polymerization %) shown in Table 1. Glycidyl methacrylate was added as the polymerized unit (A) so that the epoxy equivalent relative to the total amount of acrylic resin was the value shown in Table 1. The mixture was then polymerized to obtain acrylic resin 1 (Nagase ChemteX Corporation, "PMS-14-67") containing methyl ethyl ketone as the solvent. The solids content was 40% by weight.

[0085] [ka] (In the formula, R1 is hydrogen or a methyl group, R2 is hydrogen or an alkyl group, and X is an integer.)

[0086] (Acrylic resin 2-14) Acrylic resins 2 to 15 were prepared in the same manner as acrylic resin 1, except that the blending ratios of the polymerized units (B) to (D) were changed to the values ​​shown in Table 1 and the amount of the polymerized unit (A) added was changed so that the epoxy equivalent of each acrylic resin would be the value shown in Table 1. In acrylic resins 2 to 15, the solid content was 40% by weight.

[0087] Table 1 below further shows the number average molecular weight (Mn), weight average molecular weight (Mw), and polydispersity (Mw / Mn) of acrylic resins 1 to 15.

[0088] The molecular weights and polydispersities were determined as follows. The dried resin composition obtained above was immersed in THF, thoroughly stirred, and then suction filtered through a PTFE membrane filter to remove insoluble matter, yielding a solution of the resin composition. The number-average molecular weight Mn and weight-average molecular weight Mw of the resulting solution were calculated using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples. The polydispersity Mw / Mn was also calculated from these. A gel permeation chromatography device (Shimadzu Corporation, Nexera GPC System) was used to measure the molecular weight of each acrylic resin.

[0089] [Table 1]

[0090] (hardening agent) ·Acid anhydride (Shin Nippon Chemical Co., Ltd. “Rikacid TBN-100”, acid anhydride equivalent 464g / eq.) Amine-based curing agent (Mitsui Chemicals Fine Co., Ltd. "D2000", polyetheramine) Phenolic curing agent (Gunei Chemical Industry Co., Ltd., "ELPC75", acid equivalent 211g / eq.) Carboxylic acid curing agent (NOF Corporation, "TN-1", acid equivalent 260g / eq.)

[0091] (curing accelerator) Imidazole-based curing accelerator (Shikoku Kasei "2E4MZ", 2-ethyl-4-methylimidazole)

[0092] (surfactant) Surfactant (BYK-3440 manufactured by BYK Japan Co., Ltd.)

[0093] <Preparation of Resin Films 1 to 18> Resin varnishes 1 to 18 were prepared by adding the blending compositions (parts by mass) shown in Table 2 to a solvent (methyl ethyl ketone) so that the solid content of the composition was approximately 43% by mass. After leaving to degas, each of the resin varnishes 1 to 17 was applied to a PET film (Mitsui Chemicals Tohcello, Inc., SP-PET O1) using a bar coater. The film was then heated in an oven at 80°C for 60 minutes and then further heated at 160°C for 5 minutes to obtain semi-cured resin films 1 to 18. Resin films 1 to 12 correspond to resin films (examples) of the present invention, and resin films 13 to 18 are comparative examples.

[0094] [Table 2]

[0095] <Method of manufacturing cured resin films 1 to 18> The semi-cured resin films 1 to 18 obtained above were each further heated at 160° C. for 1 hour to obtain cured resin films 1 to 18.

[0096] <Method of manufacturing semi-cured resin coated copper foils 1 to 18> The resin varnishes 1 to 18 obtained above were applied to copper foil (CF-T9DA-SV-18, manufactured by Fukuda Metal Foil & Powder Co., Ltd.) using a bar coater. The foil was then heated in an oven at 80°C for 24 hours and then further heated at 160°C for 5 minutes to obtain semi-cured resin-coated copper foils 1 to 18 each having resin films 1 to 18 and copper foil.

[0097] <Method of manufacturing cured resin coated copper foils 1 to 18> The semi-cured resin coated copper foils 1 to 18 obtained above were each further heated at 160° C. for 1 hour to obtain cured resin coated copper foils 1 to 18.

[0098] [Evaluation test] <Method for measuring molecular weight> 1.0 g of each acrylic resin 1-15 was placed in a glass bottle and heated at 80°C for 6 hours to volatilize the solvent. Next, tetrahydrofuran was added to a concentration of 0.05-1.0 wt% and thoroughly stirred to dissolve each acrylic resin. Molecular weights were then measured by gel permeation chromatography (GPC) using Shimadzu Corporation's LC-2030C 3D Plus column (Tosoh Corporation) under the following conditions: temperature 40°C, flow rate 1.0 mL / min, and sample injection volume 0.01 mL. A refractive index (RI) detector was used.

[0099] <Method for measuring glass transition temperature and storage modulus at 200°C> Each cured resin film (cured resin films 1 to 18) was cut to a 10 mm x 30 mm size and attached to a dynamic viscoelasticity measuring device (DMS6100, manufactured by Seiko Instruments Inc.). Tests were performed with a strain amplitude of 10 μm, a frequency of 10 Hz (sine wave), and a temperature rise rate of 5 °C / min, and the peak temperature of the calculated tan δ was used as the glass transition temperature.

[0100] The storage modulus at 200°C was also measured in the same manner using the above measuring device.

[0101] <Methods for measuring tensile modulus, elongation at break, and breaking stress> Each cured resin film (cured resin films 1 to 18) was cut into a No. 6 dumbbell shape (JIS K 6251, 2017) and attached to a universal testing machine (Shimadzu Corporation, AGS-X). Tests were performed at a tensile speed of 25 mm / min, and the initial tensile modulus was calculated by finding the slope of the r-σ curve using the least squares method from all stress (σ) data corresponding to strains (r) from 0 to 0.05. Strain (r) = x / x0 (x is the distance traveled by the gripper, and x0 is the initial distance between the grippers) Stress (σ) = F / (d·l) (F is the test force, d is the film thickness, and l is the width of the test piece)

[0102] Furthermore, the elongation and breaking stress of each cured resin film when it broke were measured using the same tester.

[0103] The pass criteria for this test were a tensile modulus of 0.1 MPa or more, a breaking elongation of 50% or more, and a breaking stress of 4 Pa ​​or more.

[0104] <Method for measuring deformation amount> Each resin varnish (Resin Varnishes 1 to 18) was left to degas before being applied to a 50 μm release-treated polyimide film (Upilex S, manufactured by Ube Industries, Ltd.) using a bar coater. The film was then heated in an oven at 80°C for 60 minutes, and then at 160°C for 5 minutes to obtain a 100 μm thick semi-cured resin film (for deformation measurement) from each resin varnish. Each semi-cured resin film obtained was cut into a 100 mm x 100 mm piece and then heated at 160°C for 6 hours. After cooling, the resulting cured resin film was peeled from the polyimide film, its dimensions were measured, and the deformation was calculated. The pass criterion for warpage in this test was 0.5% or less.

[0105] <Method for measuring copper foil peel stress> Each cured resin-coated copper foil (cured resin-coated copper foils 1 to 18) was cut to a size of 10 mm x 150 mm and attached to a stainless steel plate (SUS plate) using an adhesive. The portion of the foil not coated with the resin varnish was then pinched with the fingers and peeled off 10 mm. The foil was then attached to a universal testing machine (Shimadzu Corporation, EZ Test) and subjected to a tensile test at a tensile speed of 100 mm / min, measuring the stress. The average value over the 10 mm stroke where the measured value remained stable was used as the copper foil peel stress. The pass criterion for peel stress in this test was 1.0 kN / m or more.

[0106] <Method for evaluating resin flow (embedding)> A 100 mm square copper-clad laminate consisting of a 400 μm thick glass epoxy substrate and an 18 μm thick copper foil was prepared by etching the copper foil to a wiring width of 100 μm and a wiring spacing of 100 μm. Each semi-cured resin film (semi-cured resin films 1 to 18 described above) was placed on the wiring surface of the substrate, followed by a release-coated polyimide film to obtain a laminate. This laminate was then sandwiched between two stainless steel plates (SUS plates). It was then placed in a vacuum heating press (Shindo Metal Industries Co., Ltd., ASFV-25) and heated at 160°C for 1 hour under a pressure of 1 MPa. The cross section of the resulting laminate was observed using an optical microscope to determine whether there were any gaps (voids) near the wiring.

[0107] The embeddability was evaluated as "○" if there were no voids between the wiring and the resin film, as shown in the upper diagram of Figure 1, and as "×" if voids were formed, as shown in the lower diagram of Figure 1.

[0108] The results are summarized in Table 3. The numbers in Table 3 under "Resin film used" correspond to the numbers of the resin films shown in Table 2.

[0109] [Table 3]

[0110] <Consideration> The above results demonstrate that resin films (resin films 1 to 13) using the resin composition according to the present invention have heat resistance, do not break even when stretched significantly, and have excellent breaking stress. It was also confirmed that even when the resin film according to the present invention is cured to form a cured film, deformation is unlikely to occur. Furthermore, it was also found that the film has excellent adhesion (adhesion to metal foil) and resin flow properties. It was also confirmed that a Tg of 60°C or less results in a lower modulus of elasticity at room temperature and excellent flexibility. A comparison between Example 2 and Example 13 revealed that the smaller the polydispersity Mw / / Mn, the higher the breaking strength, while the film tends to become harder and more brittle (lower breaking strength) as the polydispersity Mw / / Mn increases.

[0111] In contrast, the resin film of Comparative Example 1 (resin film 13), in which the molecular weight of the acrylic resin used was too small, was unable to obtain a sufficient breaking elongation percentage and was found to be insufficient in flexibility.On the other hand, the resin film of Comparative Example 2 (resin film 14), in which the molecular weight of the acrylic resin used was too large, resulted in poor resin flow properties.

[0112] In Comparative Example 3 (resin film 15), which used an acrylic resin not containing polymerization units (B), the breaking stress was less than 4 MPa, and the strength was insufficient. In Comparative Example 4 (resin film 16), which used an acrylic resin not containing polymerization units (C), the film underwent cure shrinkage, resulting in a deformation amount of more than 0.6 mm. In Comparative Example 5 (resin film 17), which used an acrylic resin not containing polymerization units (A) (epoxy equivalent 0), the storage modulus at 200°C could not be measured, confirming that sufficient heat resistance was not obtained.

[0113] This application is based on Japanese Patent Application No. 2020-133343, filed on August 5, 2020, the contents of which are incorporated herein by reference.

[0114] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments with reference to specific examples, drawings, etc., but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-described embodiments. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims. [Industrial Applicability]

[0115] The present invention has wide industrial applicability in the technical fields related to electronic materials and various devices using the same.

Claims

1. Contains an acrylic resin and a hardener, The acrylic resin is Polymerized units (A) of a (meth)acrylate having an epoxy group; (B) polymerized units of a (meth)acrylate having a cyano group; (C) polymerized units of a (meth)acrylate having an isobornyl group; Polymerized units (D) of an acrylic monomer selected from the group consisting of ethyl acrylate, butyl acrylate, or 2-ethylhexyl acrylate; Including, The weight average molecular weight of the acrylic resin is 50,000 or more and 3,000,000 or less, and the epoxy equivalent of the acrylic resin is 1,000 to 8,000 g / eq; The resin composition for an insulating layer of a wiring board has a storage modulus at 200°C of 0.1 MPa or more and 3.5 MPa or less after curing.

2. The resin composition according to claim 1, wherein the cured product has a tensile modulus of elasticity of 0.1 MPa or more and 0.5 GPa or less.

3. The resin composition according to claim 1 or 2, wherein the curing agent comprises at least one selected from the group consisting of an acid anhydride, an amine-based curing agent, a phenol-based curing agent, and a carboxylic acid-based curing agent.

4. The resin composition according to claim 1 , wherein the curing agent comprises a polyfunctional acid anhydride having a functionality of two or more.

5. The resin composition according to claim 3 or 4, wherein the acid anhydride equivalent of the curing agent is 100 g / eq or more and 500 g / eq or less.

6. The resin composition according to claim 1 , wherein the polydispersity (Mw / Mn) of the average molecular weight of the acrylic resin satisfies the following formula (1): 1.1≦Mw / Mn≦3.0 (1) (In the formula, Mn is the number average molecular weight, and Mw is the weight average molecular weight.)

7. The resin composition according to claim 1 , comprising 1 part by mass or more and 30 parts by mass or less of the polymerized unit (B) relative to 100 parts by mass of the acrylic resin.

8. The resin composition according to claim 1 , comprising 1 part by mass or more and 50 parts by mass or less of the polymerized unit (C) relative to 100 parts by mass of the acrylic resin.

9. The resin composition according to any one of claims 1 to 8, wherein the cured product has a glass transition temperature of 60°C or lower.

10. A resin film for use as an insulating layer in a wiring board, formed using the resin composition according to any one of claims 1 to 9.

11. A resin coated metal foil for wiring boards, comprising the resin film according to claim 10 and a metal foil overlapping the resin film.

12. A resin sheet material for an insulating layer of a wiring substrate, comprising: the resin film according to claim 9; and a support member overlapping the resin film.

13. A metal-clad laminate having an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 9 and a metal foil overlapping the insulating layer.

14. A wiring board having an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 9, and wiring provided on at least one selected from the surface and the interior of the insulating layer.

Images