Insulating film

Abstract

This insulating film comprises a cover film, a resin layer, and a support film, in said order, wherein the arithmetic average roughness Ra of the surface of the cover film on the resin layer side is at least 0.3 μm and the maximum peak height Rp is less than 4 μm.

Description

Insulating film

[0001] The present disclosure relates to insulating films.

[0002] In the field of printed wiring board production, resin compositions and solder resist films (insulating films) having a structure in which a layer containing this resin composition (hereinafter referred to as a "resin layer") is formed on a support and a protective film is disposed on the resin layer are widely used as resist materials used in etching, plating, etc. When a printed wiring board is produced using a solder resist film, first, a photosensitive layer of the solder resist film is laminated on a circuit-forming substrate (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-150543

[0004] Conventional solder resist films tend to develop voids when laminated onto substrates with minimal copper surface irregularities. The development of voids can result in reduced yields. Next-generation substrates are expected to have even less copper surface irregularities, making conventional solder resist films more susceptible to voids.

[0005] The present disclosure has been made in view of the above circumstances, and has an object to provide an insulating film that can suppress the occurrence of voids.

[0006] In order to solve the above problems, the present disclosure provides the following insulating film.

[0007] [1] An insulating film comprising a cover film, a resin layer, and a support film, in this order, wherein the surface of the cover film facing the resin layer has an arithmetic mean roughness Ra of 0.3 μm or more and a maximum peak height Rp of less than 4 μm. [2] The insulating film according to [1] above, wherein the surface of the cover film facing the resin layer has a kurtosis Rku of 3 or less. [3] An insulating film comprising a cover film, a resin layer, and a support film, in this order, wherein the surface of the cover film facing the resin layer has an arithmetic mean roughness Ra of 0.3 μm or more and a kurtosis Rku of 3 or less. [4] The insulating film according to any one of [1] to [3] above, wherein the surface of the cover film facing the resin layer has a skewness Rsk of 1 or less. [5] The insulating film according to any one of [1] to [4] above, wherein the surface of the cover film facing the resin layer has a ten-point mean roughness Rz of 4 μm or less. [6] The insulating film according to any one of [1] to [5] above, wherein the resin layer is formed from a photosensitive resin composition. [7] The insulating film according to [6] above, wherein the photosensitive resin composition contains (A) a resin having an ethylenically unsaturated bond and an acidic group, (B) a photopolymerizable compound, and (C) a photopolymerization initiator.

[0008] According to the present disclosure, it is possible to provide an insulating film that can suppress the occurrence of voids.

[0009] FIG. 1 is a cross-sectional view schematically showing an insulating film according to this embodiment.

[0010] Hereinafter, several embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0011] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. When referring to the amount of each component in a composition in this specification, if multiple substances corresponding to each component are present in the composition, this refers to the total amount of those multiple substances present in the composition, unless otherwise specified. "A or B" means that either A or B is present, or both may be present. "Solid content" refers to the non-volatile content of a resin composition excluding volatile substances (water, solvents, etc.). That is, the term "solid content" refers to components other than the solvent that remain without volatilizing when the resin composition is dried, as described below, and includes components that are liquid, syrup-like, or waxy at room temperature (25°C). In this specification, for example, "(meth)acrylic acid" means "acrylic acid" and the corresponding "methacrylic acid," and the same applies to other similar terms.

[0012] [Insulating Film] The insulating film according to this embodiment includes a cover film, a resin layer, and a support film, in this order. Fig. 1 is a cross-sectional view schematically showing the insulating film according to this embodiment. The insulating film 1 includes a cover film 30, a resin layer 20, and a support film 10, in this order. When using the insulating film 1, the cover film 30 is peeled off to expose the resin layer 20, and the resin layer 20 is laminated onto the surface to be adhered, such as a circuit board.

[0013] <Cover Film> In an insulating film according to one embodiment of the present disclosure, the surface of the cover film facing the resin layer has an arithmetic mean roughness Ra of 0.3 μm or more and a maximum peak height Rp of less than 4 μm. In an insulating film according to another embodiment of the present disclosure, the surface of the cover film facing the resin layer has an arithmetic mean roughness Ra of 0.3 μm or more and a kurtosis Rku of 3 or less. In the insulating film according to this embodiment, the surface of the cover film facing the resin layer has specific irregularities, which can suppress the occurrence of voids when the insulating film is laminated to a substrate to form a solder resist.

[0014] The arithmetic mean roughness Ra, maximum peak height Rp, kurtosis Rku, skewness Rsk, and ten-point mean roughness Rz of the cover film can be measured by photographing the surface of the resin layer side of the cover film using a shape measurement laser microscope in accordance with the provisions of ISO 25178. For example, using a measuring device VK-X-200 (manufactured by Keyence Corporation), the surface of the resin layer side of the cover film is photographed with a cutoff λs setting of 2.5 μm and λc setting of 0.8 μm, and analyzed using the attached surface analysis software, whereby the arithmetic mean roughness Ra, maximum peak height Rp, kurtosis Rku, skewness Rsk, and ten-point mean roughness Rz can be measured.

[0015] The reason why the insulating film according to the present embodiment can suppress the generation of voids is not clear, but is thought to be as follows: Note that the reason why the insulating film according to the present embodiment can suppress the generation of voids is not limited to the following.

[0016] When the arithmetic mean roughness Ra of the surface of the cover film facing the resin layer is equal to or greater than a certain value, unevenness is formed on the surface of the resin layer of the insulating film facing the cover film. Generally, the surface of the resin layer is designed to be small in order to improve adhesion, but this tends to cause voids to form when air gets between the substrate and the resin layer during lamination. In contrast, in the resin layer of the insulating film of this embodiment, the arithmetic mean roughness Ra of the surface of the cover film facing the resin layer is 0.3 μm or greater, which causes unevenness to form on the surface of the resin layer. Therefore, when the insulating film is bonded to the substrate, gaps due to the unevenness form at the contact surface between the substrate and the resin layer. The inventors speculate that these gaps serve as escape routes for air during lamination, and the escape of air suppresses the generation of voids.

[0017] Furthermore, when the convex shapes of the uneven portions on the surface of the cover film are large, large concave depressions are formed on the surface of the resin layer facing the cover film, and pinholes tend to form after lamination. In contrast, the present inventors speculate that in the resin layer of the insulating film of one embodiment of the present disclosure, the maximum peak height Rp on the surface of the resin layer facing the cover film is less than 4 μm, and in the resin layer of the insulating film of another embodiment of the present disclosure, the kurtosis Rku on the surface of the resin layer facing the cover film is 3 or less, so that large concave depressions are not formed on the surface of the resin layer facing the cover film, and pinholes are less likely to form after lamination, thereby suppressing the occurrence of voids.

[0018] The arithmetic mean roughness Ra of the surface of the cover film on the resin layer side is preferably 0.4 μm or more, more preferably 0.5 μm or more, and even more preferably 0.6 μm or more, from the viewpoint of further suppressing the generation of voids and improving the tackiness of the resin layer. Furthermore, from the viewpoint of making it easier for the resin layer to follow the uneven shape of the surface of the cover film and improving productivity, Ra is preferably 0.8 μm or less, more preferably 0.7 μm or less, and even more preferably 0.65 μm or less.

[0019] The maximum peak height Rp of the surface of the cover film on the resin layer side is preferably 3.5 μm or less, more preferably 3.0 μm or less, and even more preferably 2.5 μm or less, from the viewpoint of further suppressing the generation of voids and the flatness of the resin layer. From the viewpoint of transferability of the uneven shape to the resin layer, the maximum peak height Rp may be more than 1.4 μm, 1.5 μm or more, or 1.6 μm or more.

[0020] From the viewpoint of further suppressing the generation of voids, the kurtosis Rku of the surface of the cover film on the resin layer side may be 2.8 or less, 2.6 or less, or 2.4 or less.

[0021] To further suppress the generation of voids, the surface of the cover film on the resin layer side may have an arithmetic mean roughness Ra of 0.3 μm or more, a maximum peak height Rp of less than 4 μm, and a kurtosis Rku of 3 or less.

[0022] The surface of the cover film on the resin layer side may have a skewness Rsk of 1 or less. The occurrence of voids can be further suppressed by having the skewness Rsk of 1 or less. From the viewpoint of further suppressing the occurrence of voids, the skewness Rsk may be 0.8 or less, 0.6 or less, or 0.3 or less, or may be −1 or more, −0.8 or more, −0.6 or more, or −0.3 or more.

[0023] The ten-point average roughness Rz of the surface of the cover film on the resin layer side may be 4 μm or less. By having the ten-point average roughness Rz of 4 μm or less, the occurrence of voids can be further suppressed. From the viewpoint of further suppressing the occurrence of voids, the ten-point average roughness Rz may be 3.9 μm or less.

[0024] The surface shape of the cover film can be adjusted during production of the cover film. For example, the arithmetic mean roughness Ra, maximum peak height Rp, kurtosis Rku, skewness Rsk, and ten-point mean roughness Rz of the surface of the resin layer side of the cover film can be adjusted by adjusting the uneven pattern of a metal embossing roll (shaping roll) to be transferred during production of the cover film.

[0025] The cover film may be made of polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate (PET), polyvinyl chloride resin films, acrylonitrile-butadiene-styrene copolymer resins, or the like.

[0026] The thickness of the cover film is not particularly limited, and may be 5 μm or more and 100 μm or less, or 5 μm or more and 50 μm or less, or 50 μm or more and 100 μm or less.

[0027] <Resin Layer> The resin layer is formed from a curable resin composition. Examples of the curable resin composition include a photosensitive resin composition and a thermosetting resin composition. From the viewpoint of productivity, the resin layer is preferably formed from a photosensitive resin composition, since the via shapes can be opened all at once by photolithography.

[0028] The photosensitive resin composition may contain (A) a resin having an ethylenically unsaturated bond and an acidic group, (B) a photopolymerizable compound, and (C) a photopolymerization initiator.

[0029] (Component (A): Resin Having an Ethylenically Unsaturated Bond and an Acidic Group) The resin having an ethylenically unsaturated bond and an acidic group is not particularly limited as long as it has a photopolymerizable ethylenically unsaturated bond and an alkali-soluble acidic group.

[0030] Examples of the group having an ethylenically unsaturated bond contained in component (A) include a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, and a (meth)acryloyl group. Among these, a (meth)acryloyl group may be used from the viewpoint of reactivity and resolution. Examples of the acidic group contained in component (A) include a carboxy group, a sulfo group, and a phenolic hydroxyl group. Among these, a carboxy group may be used as the acidic group from the viewpoint of resolution.

[0031] The component (A) may be an epoxy derivative having an ethylenically unsaturated bond and an acidic group, which is obtained by reacting a resin (A') (hereinafter referred to as "component (A')") obtained by reacting (a) an epoxy resin (hereinafter referred to as "component (a)") with (b) an ethylenically unsaturated group-containing organic acid (hereinafter referred to as "component (b)"), with (c) a saturated group- or unsaturated group-containing polybasic acid anhydride (hereinafter referred to as "component (c)").

[0032] Examples of epoxy derivatives having an ethylenically unsaturated bond and an acidic group include acid-modified epoxy(meth)acrylates. Acid-modified epoxy(meth)acrylates are resins obtained by acid-modifying epoxy(meth)acrylate, which is a reaction product of components (a) and (b), with component (c). Examples of acid-modified epoxy(meth)acrylates include addition reaction products obtained by adding saturated or unsaturated polybasic acid anhydrides to an ester obtained by reacting an epoxy resin with a monocarboxylic acid having an ethylenically unsaturated bond.

[0033] Examples of component (A) include a resin (A1) (hereinafter referred to as "component (A1)") having an ethylenically unsaturated bond and an acidic group, which is obtained by using a bisphenol novolac epoxy resin (a1) (hereinafter referred to as "epoxy resin (a1)") as the component (a), and a resin (A2) (hereinafter referred to as "component (A2)") having an ethylenically unsaturated bond and an acidic group, which is obtained by using an epoxy resin (a2) (hereinafter referred to as "epoxy resin (a2)") other than the epoxy resin (a1) as the component (a). These can be used alone or in combination of two or more.

[0034] (Epoxy Resin (a1)) Examples of the epoxy resin (a1) include epoxy resins having a structural unit represented by the following formula (I) or (II): The epoxy resin (a1) may be an epoxy resin having a structural unit represented by formula (I).

[0035]

[0036] In formula (I), R １１ represents a hydrogen atom or a methyl group, and a plurality of R １１may be the same or different. １ and Y ２ each independently represents a hydrogen atom or a glycidyl group, and Y １ and Y ２ At least one of R is a glycidyl group. From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, １１ may be a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y １ and Y ２ may be a glycidyl group.

[0037] The number of structural units represented by formula (I) in the epoxy resin (a1) is 1 or more, and may be 10 to 100, 15 to 80, or 15 to 70. When the number of structural units is within the above range, the linearity of the resist pattern contour, adhesion to the copper substrate, heat resistance, and electrical insulation are easily improved. Here, the number of structural units represents an integer value in a single molecule, and represents a rational number that is an average value in an aggregate of multiple types of molecules. The same applies hereinafter to the number of structural units in structural units.

[0038]

[0039] In formula (II), R １２ represents a hydrogen atom or a methyl group, and a plurality of R １２ may be the same or different. ３ and Y ４ each independently represents a hydrogen atom or a glycidyl group, and Y ３ and Y ４ At least one of R is a glycidyl group. From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, １２ may be a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y ３ and Y ４ may be a glycidyl group.

[0040] The number of structural units represented by formula (II) in the epoxy resin (a1) is 1 or more, and may be 10 to 100, 15 to 80, or 15 to 70. When the number of structural units is within the above range, it becomes easier to improve the linearity of the resist pattern contour, adhesion to a copper substrate, and heat resistance.

[0041] In formula (II), R １２ is a hydrogen atom, and Y ３ and Y ４ The epoxy resin in which R is a glycidyl group is commercially available as the EXA-7376 series (trade name, manufactured by DIC Corporation). １２ is a methyl group, and Y ３ and Y ４ Epoxy resins in which the carboxyl group is a glycidyl group are commercially available as EPON SU8 series (trade name, manufactured by Mitsubishi Chemical Corporation).

[0042] (Epoxy Resin (a2)) The epoxy resin (a2) is not particularly limited as long as it is an epoxy resin different from the epoxy resin (a1), but from the viewpoints of suppressing the occurrence of undercut and improving the linearity of the resist pattern contour, adhesion to the copper substrate, and resolution, it may be at least one type selected from the group consisting of novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, triphenolmethane type epoxy resins, and biphenyl type epoxy resins.

[0043] Examples of novolac-type epoxy resins include epoxy resins having a structural unit represented by the following formula (III): Bisphenol A-type epoxy resins or bisphenol F-type epoxy resins include epoxy resins having a structural unit represented by the following formula (IV): Triphenolmethane-type epoxy resins include epoxy resins having a structural unit represented by the following formula (V): Biphenyl-type epoxy resins include epoxy resins having a structural unit represented by the following formula (VI):

[0044] The epoxy resin (a2) is preferably a novolac epoxy resin having a structural unit represented by the following formula (III): An example of a novolac epoxy resin having such a structural unit is a novolac epoxy resin represented by the following formula (III'):

[0045]

[0046] In formulas (III) and (III′), R １３ represents a hydrogen atom or a methyl group, and Y ５ represents a hydrogen atom or a glycidyl group, and Y ５ At least one of n is a glycidyl group. １ is a number equal to or greater than 1, and a plurality of R １３ and Y ５ From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, R １３ may be a hydrogen atom.

[0047] In formula (III′), Y is a hydrogen atom. ５ and Y, a glycidyl group ５ From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, the molar ratio of n to n may be 0 / 100 to 30 / 70 or 0 / 100 to 10 / 90. １ is 1 or more, but may be 10 to 200, 30 to 150, or 30 to 100. １ When the amount of the resist film falls within the above range, the linearity of the resist pattern contour, adhesion to the copper substrate, and heat resistance are likely to be improved.

[0048] Examples of the novolac epoxy resin represented by formula (III') include phenol novolac epoxy resin and cresol novolac epoxy resin. These novolac epoxy resins can be obtained, for example, by reacting a phenol novolac resin or a cresol novolac resin with epichlorohydrin using a known method.

[0049] Examples of the phenol novolac epoxy resin or cresol novolac epoxy resin represented by formula (III') include YDCN-701, YDCN-702, YDCN-703, YDCN-704, YDCN-704L, YDPN-638, YDPN-602 (all of which are trade names manufactured by Nippon Steel Chemical & Material Co., Ltd.), DEN-431, DEN-439 (all of which are trade names manufactured by The Dow Chemical Company), EOCN-120, EOCN- Commercially available examples include EOCN-102S, EOCN-103S, EOCN-104S, EOCN-1012, EOCN-1025, EOCN-1027, and BREN (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.), EPN-1138, EPN-1235, and EPN-1299 (all of which are trade names manufactured by BASF), and N-730, N-770, N-865, N-665, N-673, VH-4150, and VH-4240 (all of which are trade names manufactured by DIC Corporation).

[0050] The epoxy resin (a2) is preferably a bisphenol A type epoxy resin or a bisphenol F type epoxy resin having a structural unit represented by the following formula (IV): Epoxy resins having such a structural unit include, for example, bisphenol A type epoxy resins or bisphenol F type epoxy resins represented by the following formula (IV'):

[0051]

[0052] In formulas (IV) and (IV′), R １４ represents a hydrogen atom or a methyl group, and there are multiple R １４ may be the same or different, and Y ６ represents a hydrogen atom or a glycidyl group. ２ represents a number of 1 or more, and n ２ If there are two or more Y ６ may be the same or different, and at least one Y ６ is a glycidyl group.

[0053] From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, R １４ may be a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y６ may be a glycidyl group. ２ represents 1 or more, but may be 10 to 100, 10 to 80, or 15 to 60. ２ When the amount of the resist film falls within the above range, the linearity of the resist pattern contour, adhesion to the copper substrate, and heat resistance are likely to be improved.

[0054] Y in formula (IV) ６ The bisphenol A type epoxy resin or bisphenol F type epoxy resin in which Y is a glycidyl group can be, for example, ６ is a hydrogen atom, ６ ) with epichlorohydrin.

[0055] To promote the reaction between hydroxyl groups and epichlorohydrin, the reaction may be carried out in a polar organic solvent such as dimethylformamide, dimethylacetamide, or dimethylsulfoxide in the presence of an alkali metal hydroxide at a reaction temperature of 50 to 120° C. When the reaction temperature is within the above range, the reaction does not become too slow, and side reactions can be suppressed.

[0056] Examples of commercially available bisphenol A epoxy resins or bisphenol F epoxy resins represented by formula (IV') include jER807, jER815, jER825, jER827, jER828, jER834, jER1001, jER1004, jER1007, and jER1009 (all of which are trade names manufactured by Mitsubishi Chemical Corporation), DER-330, DER-301, and DER-361 (all of which are trade names manufactured by The Dow Chemical Company), and YD-8125, YDF-170, YDF-175S, YDF-2001, YDF-2004, and YDF-8170 (all of which are trade names manufactured by Nippon Steel Chemical & Material Co., Ltd.).

[0057] The epoxy resin (a2) is preferably a triphenolmethane-type epoxy resin having a structural unit represented by the following formula (V): An example of a triphenolmethane-type epoxy resin having such a structural unit is a triphenolmethane-type epoxy resin represented by the following formula (V'):

[0058]

[0059] In formulas (V) and (V′), Y ７ represents a hydrogen atom or a glycidyl group, and a plurality of Y ７ may be the same or different, and at least one Y ７ is a glycidyl group. ３ indicates a number of 1 or more.

[0060] From the viewpoint of suppressing the occurrence of undercut and upper portion loss and improving the linearity and resolution of the resist pattern contour, Y ７ Y is a hydrogen atom in ７ and Y, a glycidyl group ７ The molar ratio of Y to Y may be 0 / 100 to 30 / 70. ７ At least one of the groups is a glycidyl group. ３ is 1 or more, but may be 10 to 100, 15 to 80, or 15 to 70. ３ When the amount of the resist film falls within the above range, the linearity of the resist pattern contour, adhesion to the copper substrate, and heat resistance are likely to be improved.

[0061] As the triphenolmethane type epoxy resin represented by formula (V'), for example, FAE-2500, EPPN-501H, EPPN-502H (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.) and the like are commercially available.

[0062] The epoxy resin (a2) is preferably a biphenyl-type epoxy resin having a structural unit represented by the following formula (VI): An example of a biphenyl-type epoxy resin having such a structural unit is a biphenyl-type epoxy resin represented by the following formula (VI'):

[0063]

[0064] In formulas (VI) and (VI′), Y ８ represents a hydrogen atom or a glycidyl group, and a plurality of Y ８ may be the same or different, and at least one Y ８ is a glycidyl group. ４ indicates a number of 1 or more.

[0065] As the biphenyl type epoxy resin represented by formula (VI'), for example, NC-3000, NC-3000-L, NC-3000-H, NC-3000-FH-75M, NC-3100, CER-3000-L (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.), etc. are commercially available.

[0066] The epoxy resin (a2) is preferably at least one selected from the group consisting of novolac epoxy resins having a structural unit represented by formula (III), bisphenol A epoxy resins having a structural unit represented by formula (IV), and bisphenol F epoxy resins having a structural unit represented by formula (IV), and more preferably bisphenol F epoxy resins having a structural unit represented by formula (IV).

[0067] From the viewpoints of thermal shock resistance, warpage reduction, and resolution, a combination of a component (A1) using a bisphenol novolac epoxy resin having a structural unit represented by the above formula (I) as the component (a1) and a component (A2) using a bisphenol A epoxy resin or bisphenol F epoxy resin having a structural unit represented by the formula (IV) as the component (a2) may be used.

[0068] (Ethylenically Unsaturated Group-Containing Organic Acid (b)) Examples of the component (b) include acrylic acid; acrylic acid derivatives such as a dimer of acrylic acid, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, and α-cyanocinnamic acid; half-ester compounds which are reaction products of hydroxyl group-containing (meth)acrylates and dibasic acid anhydrides; and half-ester compounds which are reaction products of monoglycidyl ethers having an ethylenically unsaturated bond or monoglycidyl esters having an ethylenically unsaturated bond and dibasic acid anhydrides. The component (b) can be used singly or in combination of two or more.

[0069] The half-ester compound can be obtained, for example, by reacting a hydroxyl group-containing (meth)acrylate, a monoglycidyl ether having an ethylenically unsaturated bond, or a monoglycidyl ester having an ethylenically unsaturated bond with a dibasic acid anhydride.

[0070] Examples of hydroxyl group-containing (meth)acrylates, monoglycidyl ethers having an ethylenically unsaturated bond, and monoglycidyl esters having an ethylenically unsaturated bond include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and glycidyl (meth)acrylate.

[0071] Examples of dibasic acid anhydrides include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride.

[0072] In the reaction between component (a) and component (b), the reaction may be carried out in a ratio such that 0.6 to 1.05 equivalents of component (b) are used per equivalent of the epoxy groups in component (a), or in a ratio such that 0.8 to 1.0 equivalents of component (b) are used per equivalent of the epoxy groups in component (a). By carrying out the reaction in such a ratio, photosensitivity increases and the linearity of the resist pattern contour tends to be excellent.

[0073] The components (a) and (b) can be dissolved in an organic solvent and reacted. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The organic solvents may be used alone or in combination of two or more.

[0074] A catalyst may be used to promote the reaction between component (a) and component (b). Examples of the catalyst include triethylamine, benzylmethylamine, methyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, and triphenylphosphine. The catalyst may be used alone or in combination of two or more.

[0075] From the viewpoint of promoting the reaction between the component (a) and the component (b), the amount of the catalyst used may be 0.01 to 10 parts by mass, 0.05 to 2 parts by mass, or 0.1 to 1 part by mass relative to 100 parts by mass of the total of the component (a) and the component (b).

[0076] A polymerization inhibitor may be used in the reaction between component (a) and component (b) to prevent polymerization during the reaction. Examples of polymerization inhibitors include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol. One polymerization inhibitor may be used alone, or two or more polymerization inhibitors may be used in combination. From the viewpoint of improving stability, the amount of the polymerization inhibitor used may be 0.01 to 1 part by mass, 0.02 to 0.8 parts by mass, or 0.04 to 0.5 parts by mass, relative to 100 parts by mass of the total of component (a) and component (b).

[0077] The reaction temperature between the components (a) and (b) may be 60 to 150°C, 80 to 120°C, or 90 to 110°C from the viewpoint of productivity.

[0078] Component (A'), obtained by reacting components (a) and (b), has hydroxyl groups formed by a ring-opening addition reaction between the epoxy groups of component (a) and the carboxyl groups of component (b). By further reacting component (A') with component (c), an epoxy resin having ethylenically unsaturated bonds and acidic groups is obtained in which the hydroxyl groups of component (A') (including the hydroxyl groups originally present in component (a)) and the acid anhydride groups of component (c) are half-esterified.

[0079] (Polybasic Acid Anhydride (c)) Examples of the component (c) include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride. Among these, tetrahydrophthalic anhydride is preferred from the viewpoint of resolution. The component (c) may be used alone or in combination of two or more.

[0080] The reaction temperature of the component (A') and the component (c) may be 50 to 150°C, 60 to 120°C, or 70 to 100°C from the viewpoint of productivity.

[0081] If necessary, as component (a), for example, a hydrogenated bisphenol A type epoxy resin may be used in combination, or a styrene-maleic acid resin such as a hydroxyethyl (meth)acrylate modified product of a styrene-maleic anhydride copolymer may be used in combination.

[0082] In the reaction of component (A') with component (c), for example, the acid value of component (A) can be adjusted by reacting 0.1 to 1.0 equivalents of component (c) with one equivalent of hydroxyl groups in component (A').

[0083] The acid value of component (A) may be 30 to 150 mgKOH / g, 40 to 120 mgKOH / g, or 50 to 100 mgKOH / g. When the acid value of component (A) is 30 mgKOH / g or more, the photosensitive resin composition tends to have excellent solubility in a dilute alkaline solution. When the acid value of component (A) is 150 mgKOH / g or less, the electrical properties of the resin layer are easily improved.

[0084] The weight average molecular weight (Mw) of component (A) is not particularly limited, and may be 3,000 to 30,000, 4,000 to 25,000, or 5,000 to 18,000, from the viewpoints of resolution, adhesion, heat resistance, and electrical insulation.

[0085] Mw can be measured by gel permeation chromatography (GPC). Mw can be measured, for example, under the following GPC conditions, and the value converted using a calibration curve of standard polystyrene can be used as Mw. The calibration curve can be created using a five-sample set ("PStQuick MP-H" and "PStQuick B", manufactured by Tosoh Corporation) as standard polystyrene. GPC apparatus: High-speed GPC apparatus "HCL-8320GPC" (manufactured by Tosoh Corporation) Detector: Differential refractometer or UV detector (manufactured by Tosoh Corporation) Column: Column TSKgel SuperMultipore HZ-H (column length: 15 cm, column inner diameter: 4.6 mm) (manufactured by Tosoh Corporation) Eluent: Tetrahydrofuran (THF) Measurement temperature: 40°C Flow rate: 0.35 mL / min Sample concentration: 10 mg / 5 mL THF Injection amount: 20 μL

[0086] From the viewpoint of improving the heat resistance, electrical properties, and chemical resistance of the resin layer, the content of the component (A) in the photosensitive resin composition may be 20 to 80 mass %, 25 to 70 mass %, or 30 to 50 mass % based on the total solid content of the photosensitive resin composition.

[0087] When the component (A1) and the component (A2) are used in combination as the component (A), the total content of the components (A1) and (A2) in the component (A) may be 80 to 100 mass%, 90 to 100 mass%, 95 to 100 mass%, or 100 mass%, based on the total amount of the component (A), from the viewpoints of linearity of the resist pattern contour, resistance to electroless plating, and heat resistance. When the component (A1) or the component (A2) is used alone, the amount can also be appropriately selected from the above ranges.

[0088] When the component (A) is a combination of the component (A1) and the component (A2), the mass ratio (A1 / A2) thereof may be 20 / 80 to 90 / 10, 30 / 70 to 80 / 20, 40 / 60 to 75 / 25, or 50 / 50 to 70 / 30, from the viewpoints of linearity of the resist pattern contour, resistance to electroless plating, and heat resistance.

[0089] (Component (B): Photopolymerizable Compound) The photosensitive resin composition may contain a photopolymerizable compound as component (B) from the viewpoints of improving chemical resistance after exposure and increasing the difference in developer resistance between exposed and unexposed areas.

[0090] Examples of the component (B) include a photopolymerizable compound having one ethylenically unsaturated group, a photopolymerizable compound having two ethylenically unsaturated groups, and a photopolymerizable compound having three or more ethylenically unsaturated groups.

[0091] Examples of photopolymerizable compounds having one ethylenically unsaturated group include (meth)acrylic acid and (meth)acrylic acid alkyl esters. Examples of (meth)acrylic acid alkyl esters include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, and (meth)acrylic acid hydroxyethyl ester.

[0092] Examples of photopolymerizable compounds having two ethylenically unsaturated groups include polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis(4-(meth)acryloxypolyethoxypolypropoxyphenyl)propane, and bisphenol A diglycidyl ether di(meth)acrylate.

[0093] Examples of photopolymerizable compounds having three or more ethylenically unsaturated groups include (meth)acrylate compounds having a skeleton derived from trimethylolpropane, such as trimethylolpropane tri(meth)acrylate; (meth)acrylate compounds having a skeleton derived from tetramethylolmethane, such as tetramethylolmethane tri(meth)acrylate and tetramethylolmethane tetra(meth)acrylate; (meth)acrylate compounds having a skeleton derived from pentaerythritol, such as pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate; (meth)acrylate compounds having a skeleton derived from dipentaerythritol, such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate; (meth)acrylate compounds having a skeleton derived from ditrimethylolpropane, such as ditrimethylolpropane tetra(meth)acrylate; and (meth)acrylate compounds having a skeleton derived from diglycerin.

[0094] Among these, from the viewpoint of improving chemical resistance after exposure and increasing the difference in developer resistance between exposed and unexposed areas, (meth)acrylate compounds having a skeleton derived from dipentaerythritol are preferred, and dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate are more preferred.

[0095] The content of the component (B) may be 1 to 20 mass %, 2 to 15 mass %, or 4 to 12 mass %, based on the total solid content of the photosensitive resin composition.

[0096] (Component (C): Photopolymerization Initiator) The photopolymerization initiator serving as component (C) is not particularly limited as long as it can polymerize component (A) or component (B). As component (C), one type may be used alone, or two or more types may be used in combination.

[0097] Examples of the component (C) include benzoin compounds such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, Acetophenone compounds such as N,N-dimethylaminoacetophenone; anthraquinone compounds such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; ketal compounds such as acetophenone dimethyl ketal and benzyl dimethyl ketal. benzophenone compounds such as benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylamino)benzophenone, Michler's ketone, and 4-benzoyl-4'-methyldiphenyl sulfide; 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, and 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer. imidazole compounds such as 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, and 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer; acridine compounds such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide;Oxime ester compounds such as 1,2-octanedione-1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetyloxime), and 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl)oxime]; and tertiary amine compounds such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, and triethanolamine.

[0098] The content of the component (C) in the photosensitive resin composition is not particularly limited, but may be 0.1 to 15 mass%, 0.15 to 10 mass%, or 0.2 to 5 mass%, based on the total solid content of the photosensitive resin composition.

[0099] (Component (D): Thermosetting Resin) The photosensitive resin composition may further contain a thermosetting resin as component (D). Use of component (D) can improve the heat resistance, adhesiveness, chemical resistance, etc. of the resin layer formed from the photosensitive resin composition. The component (D) may be used alone or in combination of two or more.

[0100] Examples of the component (D) include epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins.

[0101] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol S type epoxy resins, novolac type epoxy resins, phenol novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, hydantoin type epoxy resins, triglycidyl isocyanurate, and bixylenol type epoxy resins.

[0102] The content of the component (D) may be 2 to 30 mass%, 5 to 25 mass%, or 8 to 20 mass%, based on the total solid content of the photosensitive resin composition. When the content of the component (D) is within the above range, the heat resistance of the formed resin layer can be further improved while maintaining good developability.

[0103] (Component (E): Elastomer) The photosensitive resin composition may further contain an elastomer as component (E). By containing component (E), it is possible to suppress a decrease in flexibility and adhesive strength caused by strain (internal stress) inside the resin due to cure shrinkage of component (A). The component (E) may be used alone or in combination of two or more types.

[0104] Examples of component (E) include styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. These elastomers are composed of a hard segment component that contributes to heat resistance and strength, and a soft segment component that contributes to flexibility and toughness.

[0105] Examples of styrene-based elastomers include styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, and styrene-ethylene-propylene-styrene block copolymers. In addition to styrene, styrene derivatives such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, and 4-cyclohexylstyrene can be used as components constituting the styrene-based elastomers.

[0106] Examples of olefin-based elastomers include ethylene-propylene copolymers, ethylene-α-olefin copolymers, ethylene-α-olefin-non-conjugated diene copolymers, propylene-α-olefin copolymers, butene-α-olefin copolymers, ethylene-propylene-diene copolymers, copolymers of non-conjugated dienes such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene with α-olefins, and carboxylic acid-modified butadiene-acrylonitrile copolymers.

[0107] As the urethane-based elastomer, a compound composed of a hard segment made of a low molecular weight (short chain) diol and diisocyanate, and a soft segment made of a high molecular weight (long chain) diol and diisocyanate can be used.

[0108] Examples of short-chain diols include ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A. The number average molecular weight of the short-chain diol is preferably 48 to 500.

[0109] Examples of long-chain diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene-neopentylene adipate). The number-average molecular weight of the long-chain diol is preferably 500 to 10,000.

[0110] As the polyester elastomer, a compound obtained by polycondensation of a dicarboxylic acid or a derivative thereof with a diol compound or a derivative thereof can be used.

[0111] Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. The dicarboxylic acids can be used alone or in combination of two or more.

[0112] Examples of the diol compound include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanediol; and aromatic diols such as bisphenol A, bis-(4-hydroxyphenyl)methane, bis-(4-hydroxy-3-methylphenyl)propane, and resorcinol.

[0113] Polyester elastomers can be multiblock copolymers that use aromatic polyesters (e.g., polybutylene terephthalate) as hard segment components and aliphatic polyesters (e.g., polytetramethylene glycol) as soft segment components. There are various grades of polyester elastomers that differ in the type, ratio, and molecular weight of the hard and soft segments.

[0114] Polyamide elastomers are broadly classified into two types: polyether block amide type and polyether ester block amide type, which use polyamide for the hard segment and polyether or polyester for the soft segment. Examples of polyamides include polyamide-6, polyamide-11, and polyamide-12. Examples of polyethers include polyoxyethylene glycol, polyoxypropylene glycol, and polytetramethylene glycol.

[0115] The acrylic elastomer may be a compound containing a structural unit based on a (meth)acrylic acid ester as a main component. Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, methoxyethyl (meth)acrylate, and ethoxyethyl (meth)acrylate. The acrylic elastomer may be a compound obtained by copolymerizing a (meth)acrylic acid ester with acrylonitrile, or may be a compound obtained by further copolymerizing a monomer having a functional group that serves as a crosslinking point. Examples of monomers having a functional group include methyl methacrylate, glycidyl methacrylate, and allyl glycidyl ether.

[0116] Examples of acrylic elastomers include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, methyl methacrylate-butyl acrylate-methacrylic acid copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer. As the acrylic elastomer, acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer or methyl methacrylate-butyl acrylate-methacrylic acid copolymer is preferred, and methyl methacrylate-butyl acrylate-methacrylic acid copolymer is more preferred.

[0117] Silicone elastomers are compounds primarily composed of organopolysiloxane. Examples of organopolysiloxane include polydimethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. Silicone elastomers may be compounds in which a portion of an organopolysiloxane is modified with a vinyl group, an alkoxy group, or the like.

[0118] From the viewpoint of improving the adhesiveness of the resin layer, the component (E) may contain a carboxylic acid-modified butadiene-acrylonitrile copolymer or a polyester-based elastomer having a hydroxyl group.

[0119] The amount of component (E) per 100 parts by mass of component (A) may be 2 to 50 parts by mass, 4 to 45 parts by mass, 6 to 40 parts by mass, or 10 to 35 parts by mass. When the amount of component (E) is within the above range, the elastic modulus of the cured film in high temperature ranges decreases, and the unexposed areas become more easily eluted in a developer.

[0120] (Component (F): Inorganic Filler) The photosensitive resin composition may further contain an inorganic filler as component (F). By containing component (F), the adhesive strength, reliability, etc. of the resin layer can be improved. The component (F) may be used alone or in combination of two or more.

[0121] Examples of inorganic fillers include silica, alumina, titania, tantalum oxide, zirconia, silicon nitride, barium titanate, barium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, lead titanate, lead zirconate titanate, lead lanthanum zirconate titanate, gallium oxide, spinel, mullite, cordierite, talc, aluminum titanate, yttria-containing zirconia, barium silicate, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, zinc oxide, magnesium titanate, hydrotalcite, mica, calcined kaolin, and carbon.

[0122] The component (F) may contain silica from the viewpoint of improving the heat resistance of the resin layer, and may contain barium sulfate from the viewpoint of improving the heat resistance and adhesive strength of the resin layer. From the viewpoint of improving the dispersibility of the inorganic filler, an inorganic filler that has been surface-treated in advance with alumina or an organic silane compound may be used.

[0123] The average particle size of the inorganic filler may be 0.01 μm or more, 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more, and may be 5.0 μm or less, 3.0 μm or less, 2.0 μm or less, or 1.5 μm or less.

[0124] The content of the component (F) may be 5 to 70 mass %, 6 to 60 mass %, or 10 to 50 mass %, based on the total solid content of the photosensitive resin composition. When the content of the component (F) is within the above range, it is possible to further improve the low thermal expansion coefficient, heat resistance, film strength, etc.

[0125] (Component (G): Pigment) The photosensitive resin composition may further contain a pigment as component (G) from the viewpoint of improving the distinguishability or appearance of the production equipment. As component (G), a colorant that develops a desired color when concealing wiring, etc., can be used. Examples of component (G) include phthalocyanine blue (copper phthalocyanine), phthalocyanine green, iodine green, diazo yellow (pigment yellow 151), crystal violet, carbon black, and naphthalene black.

[0126] From the viewpoint of further concealing the wiring, the content of the component (G) may be 0.1 to 10 mass%, 0.15 to 8 mass%, or 0.2 to 5 mass%, based on the total amount of solids in the photosensitive resin composition.

[0127] (Other Components) The photosensitive resin composition may further contain various additives as necessary. Examples of the additives include polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol; thickeners such as bentone and montmorillonite; silicone-based, fluorine-based, and vinyl resin-based antifoaming agents; silane coupling agents; and flame retardants such as brominated epoxy compounds, acid-modified brominated epoxy compounds, antimony compounds, phosphate compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters; and solvents such as aromatic hydrocarbons, aliphatic hydrocarbons, glycol ethers, esters, and petroleum-based solvents.

[0128] The thermosetting resin composition is not particularly limited and may contain a thermosetting resin, such as the thermosetting resin of component (D) of the photosensitive resin composition described above.

[0129] The thickness of the resin layer is not particularly limited and may be 5 μm to 200 μm, 5 μm to 100 μm, or 5 μm to 50 μm, or 50 μm to 200 μm, or 100 μm to 200 μm.

[0130] <Support Film> Examples of the support film include polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polyethylene film, triacetyl cellulose film, polycarbonate film, nylon film, cellophane film, and acrylic film.

[0131] The thickness of the support film is not particularly limited, and may be 5 μm or more and 100 μm or less, or 5 μm or more and 50 μm or less.

[0132] The present disclosure will be described in more detail with reference to the following examples, although the present disclosure is not limited to these examples.

[0133] [Preparation of Curable Resin Composition] The following materials were prepared.

[0134] Component (A): A resin having an ethylenically unsaturated bond and an acidic group was obtained by the following procedure. A bisphenol F novolac epoxy resin (Y in the above general formula (II)) was used. ３ is a glycidyl group, R １２ 350 parts by mass of bisphenol F novolac epoxy resin (containing a structural unit in which ⁻ is a hydrogen atom), 70 parts by mass of acrylic acid, 0.5 parts by mass of methylhydroquinone, and 120 parts by mass of carbitol acetate were charged and heated to 90°C with stirring to react and completely dissolve the mixture. The resulting solution was then cooled to 60°C, 2 parts by mass of triphenylphosphine was added, and the mixture was heated to 100°C and reacted until the acid value of the solution reached 1 mgKOH / g. To the reacted solution, 98 parts by mass of tetrahydrophthalic anhydride and 85 parts by mass of carbitol acetate were added, heated to 80°C, and reacted for 6 hours. The mixture was then cooled to room temperature to obtain an acid-modified bisphenol F novolac epoxy acrylate having a solids concentration of 73% by mass as a resin having an ethylenically unsaturated bond and an acidic group.

[0135] Component (B): Dipentaerythritol pentaacrylate (a photopolymerizable compound having an ethylenically unsaturated group) Component (C): Photopolymerization initiator 1 (trade name "IRGACURE 907", manufactured by BASF, an acetophenone-based photopolymerization initiator) Photopolymerization initiator 2 (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd., a thioxanthone-based polymerization initiator) Component (D): Thermosetting resin 1 (trade name "YX-4000", manufactured by Mitsubishi Chemical Corporation, a biphenyl-type epoxy resin) Thermosetting resin 2 (trade name "YD-8125", manufactured by Nippon Steel Chemical & Material Co., Ltd., a bisphenol A-type epoxy resin) Component (E): Elastomer 1 (trade name "PB-4700", manufactured by Daicel Corporation, an epoxidized polybutadiene) Elastomer 2 (trade name "ESPEL 1108", manufactured by Hitachi Chemical Co., Ltd., a polyester resin) Component (F): Silica (trade name "Megasil 525RCS", manufactured by Sibelco Japan Co., Ltd., average particle size 1.6 μm) Component (G): Pigment (phthalocyanine blue, trade name "NPHK-5097", manufactured by Nippon Pigment Co., Ltd., maximum particle size 0.5 μm, average particle size 0.1 μm)

[0136] The components were blended in the amounts (parts by mass, solid content) shown in Table 1 and kneaded in a three-roll mill to prepare curable resin compositions 1 and 2.

[0137]

[0138] [Preparation of cover film] A polypropylene resin (manufactured by Japan Polypropylene Corporation) was extruded at 250 ° C. from a 60 mm melt extruder into a film-forming device having a cooling roller and a shaping roller facing each other to obtain a cover film before stretching. The shaping roller used had a wrinkle-like uneven structure consisting of a plurality of protrusions and a plurality of grooves on its surface. The obtained cover film before stretching was cooled and solidified with a cooling roll at 30 ° C., and then stretched 4 times in the machine direction (MD) at 130 ° C., and then both ends of the film width direction were clamped with clips, preheated at 170 ° C., and stretched 8 times in the width direction (TD) at 150 ° C., and heat-set at 160 ° C. while relaxing by 6.0% in the width direction (TD) to obtain a cover film 1 having a thickness of 15 μm.

[0139] Cover films 2 to 7 were obtained in the same manner as cover film 1, except that shaping rollers with different shapes of wrinkle-like uneven structures on the surface were used.

[0140] The surfaces of the resulting cover films 1 to 7 to be bonded to the resin layer were observed with an optical microscope to confirm that they had an uneven structure. The surfaces of the cover films 1 to 7 to be bonded to the resin layer were also observed at a magnification of 150x using a laser microscope (Laser Microscope VK-X-200, manufactured by Keyence Corporation), and the arithmetic mean roughness Ra, maximum peak height Rp, kurtosis Rku, skewness Rsk, and ten-point mean roughness Rz were determined according to the provisions of ISO 25178. The results are shown in Table 2.

[0141]

[0142] [Preparation of insulating film and laminate for evaluation test] (Example 1) Curable resin composition 1 was applied to a film (product name: G2, support film) manufactured by Teijin DuPont Films Co., Ltd. so that the thickness after drying was 10 μm. The coating was dried at 90° C. for 3 minutes to obtain a support film with a resin layer. The uneven surface of cover film 1 serving as a surface protective layer (surface layer) and the resin layer surface of the support film with a resin layer were bonded together using a roll laminator in a clean room, and aging was performed for 1 day in an environment of 23° C. and 50% relative humidity to produce an insulating film.

[0143] The copper foil surface of a printed wiring board substrate (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-679") in which 12 μm thick copper foil was laminated on a glass epoxy base material was treated with a roughening pretreatment solution (manufactured by MEC Co., Ltd., product name "CZ-8100"), then washed with water and dried to obtain a roughening pretreated printed wiring board substrate. Next, the cover film was peeled off and removed from the obtained insulating film, and the exposed resin layer was placed so as to abut against the copper foil of the roughening pretreated printed wiring board substrate. Then, a lamination process was performed using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500"). The lamination conditions were a press hot plate temperature of 70 ° C, a vacuum time of 20 seconds, a lamination press time of 30 seconds, an atmospheric pressure of 4 kPa or less, and a pressure of 0.4 MPa. After lamination, the laminate was left at room temperature for at least 1 hour to obtain a laminate for evaluation in which a resin layer and a support film were laminated in this order on the copper foil surface of the substrate for printed wiring board.

[0144] Examples 2 to 6 and Comparative Examples 1 to 8 Insulating films and laminates for evaluation tests were prepared in the same manner as in Example 1, except that the curable resin compositions and cover films shown in Tables 3 and 4 were used.

[0145] [Resolution Evaluation Test] After peeling and removing the support film from the evaluation laminate obtained above, a 41-step tablet was placed on the laminate and exposed using a direct imaging exposure device (manufactured by Oak Manufacturing Co., Ltd., product name "DXP-3512") using an ultra-high pressure mercury lamp as a light source. The exposure pattern used was a pattern in which dots with diameters of φ30 to 100 μm were arranged in a grid pattern. After exposure, the laminate was left at room temperature for 30 minutes, and then the unexposed resin layer was spray-developed for 60 seconds using a 1% by mass aqueous solution of sodium carbonate at 30°C. After development, the amount of exposure energy at which the number of remaining gloss steps on the 41-step tablet was 10.0 was determined as the sensitivity of the resin layer (unit: mJ / cm). ２ Using the pattern exposed at this sensitivity, the resolution of the vias provided in the resin layer was evaluated according to the following evaluation criteria.

[0146] The resolution was evaluated by exposing the sample with an exposure energy amount that resulted in a step number of 10.0, followed by spray development, and then observing the via pattern using an optical microscope. The openings of the φ50 μm and φ60 μm via portions of the dot pattern were evaluated according to the following criteria. The results are shown in Tables 3 and 4. A: The minimum diameter of the opening was 60 μm or less. B: The minimum diameter of the opening was more than 60 μm. C: No cured film was obtained.

[0147] [Evaluation Test for Number of Defects] A printed wiring board having a copper thickness of 8 μm, L (line: wiring width) / S (space: spacing width) = 20 / 20 μm, and a linear pattern circuit of 1000 μm in length was pretreated by etching equivalent to 1.0 μm using a CZ-8101 process manufactured by MEC Co., Ltd. Next, the cover film was peeled off from the evaluation laminate prepared by the above method, and the exposed resin layer was laminated onto the etched surface of the board using a vacuum laminator (MVLP-500: Meiki Seisakusho Co., Ltd.) at 80 ° C. under a vacuum pressure of 4 hPa and a vacuum time of 20 seconds. After lamination, air was observed at the boundary between the lines and spaces of the evaluation board, and it was confirmed using an optical microscope whether bubbles (voids) had occurred in the resin layer, and the evaluation was evaluated according to the following criteria. The results are shown in Tables 3 and 4. A: No voids were observed. B: One or more voids were observed.

[0148]

[0149]

[0150] 1...insulating film, 10...support film, 20...resin layer, 30...cover film

Claims

1. The device comprises a cover film, a resin layer, and a support film in this order. An insulating film wherein the arithmetic mean roughness Ra of the surface on the resin layer side of the cover film is 0.3 μm or more, and the maximum peak height Rp is greater than 1.4 μm and less than 4 μm.

2. The insulating film according to claim 1, wherein the kurtosis Rku of the surface of the cover film on the resin layer side is 3 or less.

3. The device comprises a cover film, a resin layer, and a support film in this order. An insulating film wherein the arithmetic mean roughness Ra of the surface on the resin layer side of the cover film is 0.3 μm or more, the maximum peak height Rp is greater than 1.4 μm, and the crustosis Rku is 3 or less.

4. The insulating film according to any one of claims 1 to 3, wherein the skewness Rsk of the surface of the cover film on the resin layer side is 1 or less.

5. The insulating film according to any one of claims 1 to 3, wherein the ten-point average roughness Rz of the surface on the resin layer side of the cover film is 4 μm or less.

6. The insulating film according to any one of claims 1 to 3, wherein the resin layer is formed from a photosensitive resin composition.

7. The insulating film according to claim 6, wherein the photosensitive resin composition comprises (A) a resin having an ethylenically unsaturated bond and an acidic group, (B) a photopolymerizable compound, and (C) a photopolymerization initiator.