Photosensitive resin composition, photosensitive element, printed wiring board, and production method for printed wiring board

Abstract

A photosensitive resin composition containing (A) an acid-modified vinyl group-containing resin, (B) a thermosetting resin, (C) a photopolymerizable compound, (D) a photopolymerization initiator, and (E) an inorganic filler, wherein the inorganic filler (E) contains a first inorganic filler having an average particle size of 0.5 μm or more and a second inorganic filler having an average particle size of 0.3 μm or less, and the solid content mass ratio of the first inorganic filler content to the second inorganic filler content is 6:4 to 8:2.

Description

Photosensitive resin composition, photosensitive element, printed wiring board, and method for producing printed wiring board

[0001] The present disclosure relates to a photosensitive resin composition, a photosensitive element, a printed wiring board, and a method for producing a printed wiring board.

[0002] In the field of printed wiring boards, permanent resists are formed on printed wiring boards. The permanent resists have the role of preventing corrosion of the conductor layers and maintaining electrical insulation between the conductor layers when the printed wiring board is in use. In recent years, permanent resists have also come to function as solder resist films that prevent solder from adhering to unnecessary portions of the conductor layers of the printed wiring board in processes such as flip-chip mounting and wire bonding mounting of semiconductor elements on the printed wiring board via solder.

[0003] Conventionally, permanent resists have been produced by screen printing using a thermosetting resin composition or by a photographic method using a photosensitive resin composition. For example, in flexible wiring boards using mounting methods such as FC (Flip Chip), TAB (Tape Automated Bonding), and COF (Chip On Film), a thermosetting resin paste is screen-printed and thermally cured to form a permanent resist, except for IC chips, electronic components, or LCD (Liquid Crystal Display) panels and connection wiring pattern portions (see, for example, Patent Document 1).

[0004] In semiconductor package substrates such as BGA (ball grid array) and CSP (chip size package) mounted on electronic components, it is necessary to remove the permanent resist from the bonding area in order to (1) flip-chip mount a semiconductor element onto the semiconductor package substrate via solder, (2) wire-bond the semiconductor element to the semiconductor package substrate, and (3) solder-bond the semiconductor package substrate to a motherboard. A photographic method is used to form an image on the permanent resist, in which a photosensitive resin composition is applied and dried, and then selectively irradiated with actinic rays such as ultraviolet light to harden it, and only the unirradiated areas are removed by development to form an image. Because the photographic method is suitable for mass production due to its ease of operation, it is widely used in the electronic materials industry for forming images on photosensitive materials (see, for example, Patent Document 2).

[0005] JP 2003-198105 A JP 2011-133851 A

[0006] In response to the increasing density of printed wiring boards, even higher performance is being demanded of permanent resists (solder resists). In particular, requirements for resolution and insulation reliability are increasing year by year, making it important to achieve a high level of compatibility between these properties. However, while permanent resists formed from conventional photosensitive resin compositions can form large-diameter via patterns with a film thickness of, for example, 18 μm, they are prone to undercutting when forming large-diameter via patterns with a film thickness of 25 μm using the same exposure dose as for a film thickness of 18 μm, resulting in poor thickness tolerance. Furthermore, permanent resists formed from conventional photosensitive resin compositions may experience short circuits due to migration in HAST (Highly Accelerated Stress Test), an insulation reliability evaluation, when the line width / space width is 10 μm / 10 μm, within a test time of less than 200 hours.

[0007] The present disclosure aims to provide a photosensitive resin composition that can form a permanent resist that has good resolution at both 18 μm and 25 μm film thicknesses under the same exposure conditions and that has excellent insulation reliability, as well as a photosensitive element and a printed wiring board that use the photosensitive resin composition, and a method for producing a printed wiring board.

[0008] In order to solve the above problems, the present disclosure provides the following photosensitive resin composition, photosensitive element, printed wiring board, and method for producing a printed wiring board.

[0009] [1] A photosensitive resin composition comprising (A) an acid-modified vinyl group-containing resin, (B) a thermosetting resin, (C) a photopolymerizable compound, (D) a photopolymerization initiator, and (E) an inorganic filler, wherein the (E) inorganic filler comprises a first inorganic filler having an average particle size of 0.5 μm or more and a second inorganic filler having an average particle size of 0.3 μm or less, and wherein the solids mass ratio of the content of the first inorganic filler to the content of the second inorganic filler is 6:4 to 8:2. [2] The photosensitive resin composition according to [1] above, wherein the content of the (E) component is 10 to 80 mass% based on the total solids content of the photosensitive resin composition. [3] The photosensitive resin composition according to [1] or [2] above, wherein the first inorganic filler and the second inorganic filler are both inorganic oxide fillers. [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the first inorganic filler and the second inorganic filler are both spherical silica fillers. [5] The photosensitive resin composition according to any one of [1] to [4] above, further comprising (F) a photosensitizer. [6] A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer comprises the photosensitive resin composition according to any one of [1] to [5] above. [7] A printed wiring board comprising a permanent resist comprising a cured product of the photosensitive resin composition according to any one of [1] to [5] above. [8] A method for producing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of [1] to [5] above; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form a permanent resist. [9] A method for manufacturing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element described in [6] above; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form a permanent resist.

[0010] According to the present disclosure, it is possible to provide a photosensitive resin composition that can form a permanent resist that has good resolution at both 18 μm and 25 μm film thicknesses under the same exposure conditions and that has excellent insulation reliability, as well as a photosensitive element, a printed wiring board, and a method for manufacturing a printed wiring board that use the photosensitive resin composition.

[0011] FIG. 1 is a cross-sectional view schematically illustrating a photosensitive element according to an embodiment of the present invention.

[0012] The present disclosure will be described in detail below. In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended function of the process is achieved. The term "layer" encompasses not only a structure that is formed over the entire surface when observed in a plan view, but also a structure that is formed only on a portion of the surface. Numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples.

[0013] When referring to the amount of each component in a composition in this specification, if there are multiple substances corresponding to each component in the composition, the total amount of those multiple substances present in the composition is meant unless otherwise specified.

[0014] In this specification, "(meth)acrylate" means at least one of "acrylate" and its corresponding "methacrylate," and the same applies to other similar expressions such as (meth)acrylic acid and (meth)acryloyl. In this specification, "solid content" refers to the non-volatile content excluding volatile substances (water, solvent, etc.) contained in the photosensitive resin composition, and includes components that are liquid, syrup-like, or waxy at room temperature (around 25°C).

[0015] [Photosensitive Resin Composition] The photosensitive resin composition according to this embodiment contains (A) an acid-modified vinyl group-containing resin, (B) a thermosetting resin, (C) a photopolymerizable compound, (D) a photopolymerization initiator, and (E) an inorganic filler, wherein the inorganic filler contains a first inorganic filler having an average particle size of 0.5 μm or more and a second inorganic filler having an average particle size of 0.3 μm or less. In the photosensitive resin composition, the solids mass ratio of the content of the first inorganic filler to the content of the second inorganic filler (first inorganic filler:second inorganic filler) is 6:4 to 8:2. The photosensitive resin composition according to this embodiment is a negative-tone photosensitive resin composition, and a cured film of the photosensitive resin composition can be suitably used as a permanent resist. Below, each component used in the photosensitive resin composition according to this embodiment is described in more detail.

[0016] (Component (A): Acid-Modified Vinyl Group-Containing Resin) The photosensitive resin composition according to this embodiment contains an acid-modified vinyl group-containing resin as component (A). The acid-modified vinyl group-containing resin is not particularly limited as long as it has a vinyl bond that is a photopolymerizable ethylenically unsaturated bond and an alkali-soluble acidic group.

[0017] 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, from the viewpoint of reactivity and resolution, a (meth)acryloyl group is preferred. Examples of the acidic group contained in component (A) include a carboxy group, a sulfo group, and a phenolic hydroxyl group. Among these, from the viewpoint of resolution, a carboxy group is preferred.

[0018] The component (A) is preferably an acid-modified vinyl group-containing epoxy derivative obtained by reacting (c) a saturated or unsaturated group-containing polybasic acid anhydride (hereinafter sometimes referred to as “component (c)”) with a resin (A′) obtained by reacting (a) an epoxy resin (hereinafter sometimes referred to as “component (a)”) with (b) an ethylenically unsaturated group-containing organic acid (hereinafter sometimes referred to as “component (b)”).

[0019] Examples of acid-modified vinyl group-containing epoxy derivatives 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 esters obtained by reacting epoxy resins with vinyl group-containing monocarboxylic acids.

[0020] Examples of the component (A) include an acid-modified vinyl group-containing resin (A1) (hereinafter, sometimes referred to as “component (A1)”) obtained by using a bisphenol novolac epoxy resin (a1) (hereinafter, sometimes referred to as “epoxy resin (a1)”) as the component (a), and an acid-modified vinyl group-containing resin (A2) (hereinafter, sometimes referred to as “component (A2)”) obtained by using an epoxy resin (a2) (hereinafter, sometimes referred to as “epoxy resin (a2)”) other than the epoxy resin (a1) as the component (a).

[0021] Examples of the epoxy resin (a1) include epoxy resins having a structural unit represented by the following formula (I) or (II).

[0022]

[0023] In formula (I), R １１ represents a hydrogen atom or a methyl group, and a plurality of R １１ may 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 is preferably a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y １ and Y ２ is preferably a glycidyl group.

[0024] 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 of a structural unit 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 of a structural unit.

[0025]

[0026] 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 is preferably a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y ３ and Y ４ is preferably a glycidyl group.

[0027] 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.

[0028] 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 available as EXA-7376 series (trade name, manufactured by DIC Corporation), and １２ is a methyl group, and Y ３ and Y ４ Epoxy resins in which .alpha. is a glycidyl group are commercially available as EPON SU8 series (trade name, manufactured by Westlake).

[0029] The epoxy resin (a2) is not particularly limited as long as it is an epoxy resin different from the epoxy resin (a1). However, 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 is preferable that the epoxy resin (a2) be at least one selected from the group consisting of novolac epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, triphenolmethane epoxy resins, and biphenyl epoxy resins.

[0030] 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):

[0031] 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'):

[0032]

[0033] 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 is preferably a hydrogen atom.

[0034] 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.

[0035] 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.

[0036] Examples of commercially available phenol novolac epoxy resins or cresol novolac epoxy resins represented by formula (III') include YDCN-700-7, YDCN-700-10, YDCN-704, YDCN-704A, and YDPN-638 (all of which are trade names manufactured by Nippon Steel Chemical & Material Co., Ltd.), EOCN-102S, EOCN-103S, EOCN-104S, EOCN-1012, EOCN-1027, and BREN-S (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.), and N-740, N-770, N-665, and N-673 (all of which are trade names manufactured by DIC Corporation).

[0037] 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'):

[0038]

[0039] 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.

[0040] From the viewpoint of suppressing the occurrence of undercut and improving the linearity and resolution of the resist pattern contour, R １４ is preferably a hydrogen atom, and from the viewpoint of further improving thermal shock resistance, Y ６ is preferably 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.

[0041] 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.

[0042] Commercially available examples of the bisphenol A type epoxy resin or bisphenol F type epoxy resin represented by formula (IV') include jER807, jER825, jER827, jER828, jER834, jER1004F, jER1007FS and jER1009F (all of which are product names manufactured by Mitsubishi Chemical Corporation), YD-8125, YDF-170, YDF-2001, YDF-2004 and YDF-8170C (all of which are product names manufactured by Nippon Steel Chemical & Material Co., Ltd.), and the like.

[0043] 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'):

[0044]

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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'):

[0049]

[0050] 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.

[0051] As the biphenyl type epoxy resin represented by formula (VI'), for example, NC-3000, NC-3000-L, NC-3000-H, NC-3000-FH-75M (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.) and the like are commercially available.

[0052] 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).

[0053] From the viewpoint of further improving thermal shock resistance, warpage reduction, and resolution, a component (A1) using a bisphenol novolac epoxy resin having a structural unit represented by formula (II) as the epoxy resin (a1) and a component (A2) using a bisphenol A epoxy resin or bisphenol F epoxy resin having a structural unit represented by formula (IV) as the epoxy resin (a2) may be used in combination.

[0054] Examples of component (b) include acrylic acid, acrylic acid dimers, methacrylic acid, acrylic acid derivatives such as 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 vinyl group-containing monoglycidyl ethers or vinyl group-containing monoglycidyl esters and dibasic acid anhydrides. Component (b) may be used singly or in combination of two or more.

[0055] The half-ester compound can be obtained, for example, by reacting a hydroxyl group-containing (meth)acrylate, a vinyl group-containing monoglycidyl ether, or a vinyl group-containing monoglycidyl ester with a dibasic acid anhydride.

[0056] Examples of hydroxyl group-containing (meth)acrylates, vinyl group-containing monoglycidyl ethers, and vinyl group-containing monoglycidyl esters 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.

[0057] 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.

[0058] In the reaction between component (a) and component (b), the ratio of component (b) is preferably 0.6 to 1.05 equivalents, and more preferably 0.8 to 1.0 equivalents, of component (b) per equivalent of the epoxy groups in component (a). Reaction at such a ratio tends to increase photosensitivity and result in excellent linearity of the resist pattern contour.

[0059] A polymerization inhibitor may be used in the reaction between component (a) and component (b) to prevent polymerization during the reaction. Examples of the polymerization inhibitor include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol. One type of polymerization inhibitor may be used alone, or two or more types may be used in combination.

[0060] 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 the components (a) and (b).

[0061] 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 acid-modified vinyl group-containing resin 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.

[0062] Examples of 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. Component (c) may be used alone or in combination of two or more.

[0063] 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').

[0064] If necessary, a hydrogenated bisphenol A type epoxy resin may be used in part as component (a), or a styrene-maleic acid resin such as a hydroxyethyl (meth)acrylate modified product of a styrene-maleic anhydride copolymer may be used in part.

[0065] From the viewpoints of suppressing the occurrence of undercuts and further improving adhesion to the copper substrate, thermal shock resistance, and resolution, the component (A) preferably contains the component (A1), and from the viewpoint of particularly improving adhesion strength, it is more preferable for the component (A) to contain the component (A1) and the component (A2).

[0066] When the component (A) is a combination of the component (A1) and the component (A2), the mass ratio of (A1) / (A2) is not particularly limited, but from the standpoint of improving the linearity of the resist pattern contour, the electroless plating resistance, and the heat resistance, it may be 20 / 80 to 90 / 10, 30 / 70 to 80 / 20, 40 / 60 to 75 / 25, or 50 / 50 to 70 / 30.

[0067] The acid value of the (A) component is not particularly limited. From the viewpoint of improving the solubility of the unexposed area in an alkaline aqueous solution, the acid value of the (A) component may be 30 mgKOH / g or more, 40 mgKOH / g or more, or 50 mgKOH / g or more. From the viewpoint of improving the electrical properties of the cured film, the acid value of the (A) component may be 150 mgKOH / g or less, 120 mgKOH / g or less, or 100 mgKOH / g or less.

[0068] The weight average molecular weight (Mw) of the (A) component is not particularly limited. From the viewpoint of improving the adhesion of the cured film, the Mw of the (A) component may be 3,000 or more, 4,000 or more, or 5,000 or more. From the viewpoint of improving the resolution of the photosensitive layer, the Mw of the (A) component may be 30,000 or less, 25,000 or less, or 18,000 or less.

[0069] 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

[0070] From the viewpoint of improving the heat resistance, electrical properties, and chemical resistance of the permanent resist, the content of the component (A) in the photosensitive resin composition may be 20 to 70 mass %, 25 to 60 mass %, or 30 to 50 mass % based on the total solid content of the photosensitive resin composition.

[0071] (Component (B): Thermosetting Resin) The photosensitive resin composition according to this embodiment uses a thermosetting resin as component (B), which can improve the heat resistance, adhesiveness, and chemical resistance of a cured film (permanent resist) formed from the photosensitive resin composition. The component (B) may be used alone or in combination of two or more.

[0072] Examples of component (B) 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.

[0073] 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, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, hydantoin type epoxy resins, triglycidyl isocyanurate, and bixylenol type epoxy resins.

[0074] The content of the component (B) 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 (B) is within the above range, the heat resistance of the formed cured film can be further improved while maintaining good developability.

[0075] (Component (C): Photopolymerizable Compound) The component (C) is not particularly limited as long as it is a compound having a functional group exhibiting photopolymerizability. The component (C) may be a photopolymerizable compound having an ethylenically unsaturated group but not an acidic group. The component (C) preferably includes at least one selected from the group consisting of (Ci) a monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group, (Cii) a bifunctional vinyl monomer having two polymerizable ethylenically unsaturated groups, and (Ciii) a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups, and more preferably includes at least the component (Ciii). The components (Ci) to (Ciii) preferably have a molecular weight of 1,000 or less.

[0076] ((Ci) Monofunctional Vinyl Monomer) Examples of the monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group include (meth)acrylic acid and (meth)acrylic acid alkyl esters. Examples of the (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. The (Ci) component may be used alone or in combination of two or more.

[0077] ((Cii) Bifunctional Vinyl Monomer) Examples of the bifunctional vinyl monomer having two polymerizable 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, bisphenol A diglycidyl ether di(meth)acrylate, etc. The component (Cii) may be used alone or in combination of two or more.

[0078] ((Ciii) Multifunctional vinyl monomers) Examples of the polyfunctional vinyl monomer having at least three polymerizable 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. Among these, from the viewpoint of improving chemical resistance after curing (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 hexa(meth)acrylate is more preferred. One type of component (Ciii) may be used alone, or two or more types may be used in combination.

[0079] The content of the component (C) in the photosensitive resin composition is not particularly limited, but may be 0.2 to 15 mass%, 0.5 to 10 mass%, or 1 to 5 mass%, based on the total amount of solids in the photosensitive resin composition.

[0080] (Component (D): Photopolymerization Initiator) The photopolymerization initiator serving as component (D) is not particularly limited as long as it can polymerize components (A) and (C). As component (D), one type may be used alone, or two or more types may be used in combination.

[0081] Examples of the component (D) include acetophenone compounds such as 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-[4-(methylthio)phenyl]-2-morpholino-1-propane, and N,N-dimethylaminoacetophenone; anthraquinone compounds such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, and the like. benzophenone compounds such as benzophenone, 4,4'-bis(diethylamino)benzophenone, Michler's ketone, 4-benzoyl-4'-methyldiphenyl sulfide; acridine compounds such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and 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), 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl)oxime].

[0082] The content of the component (D) in the photosensitive resin composition is not particularly limited, but may be 0.2 to 15 mass%, 0.5 to 10 mass%, or 1 to 5 mass%, based on the total solid content of the photosensitive resin composition.

[0083] (Component (E): Inorganic Filler) The photosensitive resin composition according to this embodiment can improve resolution and thickness tolerance by using inorganic fillers with different average particle sizes in combination as component (E) at a specific mass ratio, and can obtain good resolution at both 18 μm and 25 μm film thicknesses under the same exposure conditions, while also forming a permanent resist with excellent insulation reliability. Component (E) contains a first inorganic filler with an average particle size of 0.5 μm or more and a second inorganic filler with an average particle size of 0.3 μm or less, with a solids mass ratio (first inorganic filler:second inorganic filler) in the range of 6:4 to 8:2.

[0084] Examples of materials for the inorganic filler 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.

[0085] The component (E) may contain a silica filler from the viewpoint of improving the heat resistance of the permanent resist, or may contain a barium sulfate filler from the viewpoint of improving the heat resistance and adhesive strength of the permanent resist, or may contain a silica filler and a barium sulfate filler. Furthermore, the component (E) may contain an inorganic oxide filler or may contain a silica filler from the viewpoint of improving heat dissipation. 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.

[0086] The first inorganic filler and the second inorganic filler may both be inorganic oxide fillers from the viewpoint of improving heat dissipation, and may be silica fillers from the viewpoint of improving the heat resistance of the permanent resist.

[0087] There are no particular restrictions on the shape of component (E), but from the perspective of improving crack resistance, it may be spherical.

[0088] The average particle size of the first inorganic filler is 0.5 μm or more, and from the viewpoint of improving the dispersibility of the filler, may be 0.5 to 5.0 μm, 0.5 to 3.0 μm, 0.5 to 2.0 μm, or 0.5 to 1.0 μm. One type of first inorganic filler may be used alone, or two or more types may be used in combination.

[0089] The second inorganic filler has an average particle size of 0.3 μm or less, and from the viewpoint of improving light transmittance, may be 0.001 to 0.3 μm, 0.005 to 0.3 μm, 0.01 to 0.3 μm, or 0.1 to 0.3 μm. One type of second inorganic filler may be used alone, or two or more types may be used in combination.

[0090] Component (E) may or may not further contain an inorganic filler other than the first inorganic filler and the second inorganic filler, i.e., a third inorganic filler having an average particle size of more than 0.3 μm and less than 0.5 μm. The content of the third inorganic filler may be 10 mass% or less, or may be 0 mass%, based on the total amount of component (E).

[0091] The average particle size of component (E) is the average particle size of the inorganic filler in a state dispersed in the photosensitive resin composition, and is a value obtained by measuring as follows: First, the photosensitive resin composition is diluted 1000 times with methyl ethyl ketone, and then the particles dispersed in the solvent are measured using a submicron particle analyzer (manufactured by Beckman Coulter, Inc., product name "N5") in accordance with international standard ISO 13321 at a refractive index of 1.38, and the particle size at an integrated value of 50% (volume basis) in the particle size distribution is taken as the average particle size.

[0092] The content of component (E) may be 5 to 80 mass%, 5 to 70 mass%, 6 to 60 mass%, or 10 to 50 mass%, based on the total solid content of the photosensitive resin composition. Furthermore, in component (E), the solid content mass ratio of the content of the first inorganic filler to the content of the second inorganic filler (first inorganic filler:second inorganic filler) may be 6:4 to 8:2, or 6.5:3.5 to 7.5:2.5.

[0093] (Component (F): Photosensitizer) The photosensitive resin composition of the present embodiment may further contain a photosensitizer as the component (F). When the photosensitive resin composition contains the component (F), it is possible to effectively utilize the absorption wavelength of the actinic radiation used for exposure.

[0094] Examples of the photosensitizer serving as component (F) include thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; phosphine compounds such as triphenylphosphine; toluidine compounds such as N,N-dimethyltoluidine; anthracene compounds such as 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, and 2-ethyl-9,10-diethoxyanthracene; perylene compounds; coumarin compounds; pyrarizone compounds; oxazole compounds; benzoxazole compounds; thiazole compounds; triazole compounds; stilbene compounds; triazine compounds; thiophene compounds; naphthalimide compounds; and triarylamine compounds.

[0095] From the viewpoint of maintaining a good via shape, the photosensitizer is preferably 2,4-dimethylthioxanthone or 2,4-diethylthioxanthone, and more preferably 2,4-diethylthioxanthone. Use of 2,4-diethylthioxanthone tends to reduce light scattering to unexposed areas, thereby maintaining a good via shape.

[0096] The content of the component (F) is preferably 0.01 to 5 mass%, more preferably 0.05 to 3 mass%, even more preferably 0.1 to 2 mass%, and particularly preferably 0.3 to 1.5 mass%, based on the total solid content of the photosensitive resin composition.

[0097] (Component (G): Pigment) The photosensitive resin composition according to this embodiment 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 (conductor pattern) or the like can be used. The component (G) may be used alone or in combination of two or more.

[0098] Examples of the component (G) include phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, titanium oxide, carbon black, and naphthalene black.

[0099] From the viewpoints of making the production equipment easier to identify and further concealing the wiring, the content of the component (G) may be 0.01 to 5.0 mass%, 0.03 to 3.0 mass%, or 0.05 to 2.0 mass%, based on the total amount of solids in the photosensitive resin composition.

[0100] (Other Components) The photosensitive resin composition according to this embodiment may further contain various additives as needed. Examples of the additives include polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol; silicone-based, fluorine-based, and vinyl resin-based antifoaming agents; silane coupling agents; and flame retardants such as phosphate compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters.

[0101] The photosensitive resin composition according to this embodiment may contain an organic filler such as a resin filler, but from the viewpoint of resolution, it may not contain the organic filler. The content of the organic filler in the photosensitive resin composition may be 1 mass % or less, or may be 0 mass %, based on the total amount of solids in the photosensitive resin composition.

[0102] (Solvent) The photosensitive resin composition according to this embodiment contains a solvent for dissolving and dispersing each component, which makes it easy to apply the composition onto a substrate and allows a coating film of uniform thickness to be formed.

[0103] Examples of the 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; and esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate. The solvents may be used alone or in combination of two or more.

[0104] The amount of the solvent to be added is not particularly limited, but the ratio of the solvent in the photosensitive resin composition may be 10 to 50% by mass, 20 to 40% by mass, or 25 to 35% by mass.

[0105] The photosensitive resin composition of this embodiment can be prepared by uniformly mixing the above-mentioned components using a roll mill, a bead mill, or the like.

[0106] [Photosensitive Element] The photosensitive element according to this embodiment includes a support film and a photosensitive layer containing the above-described photosensitive resin composition. Fig. 1 is a cross-sectional view schematically showing the photosensitive element according to this embodiment. As shown in Fig. 1, the photosensitive element 1 includes a support film 10 and a photosensitive layer 20 formed on the support film 10.

[0107] The photosensitive element 1 can be produced by applying the photosensitive resin composition according to this embodiment onto a support film 10 by a known method such as reverse roll coating, gravure roll coating, comma coating, or curtain coating, and then drying the coating to form a photosensitive layer 20.

[0108] Examples of the support film include polyester films such as polyethylene terephthalate and polybutylene terephthalate, and polyolefin films such as polypropylene and polyethylene. The thickness of the support film may be, for example, 5 to 100 μm. The thickness of the photosensitive layer may be, for example, 5 to 50 μm, 5 to 40 μm, 10 to 30 μm, 15 to 30 μm, 20 to 30 μm, or 25 to 30 μm. The surface roughness of the support film is not particularly limited, but the arithmetic mean roughness (Ra) may be 1000 nm or less, 500 nm or less, or 250 nm or less.

[0109] The coating film can be dried by hot air drying, far infrared drying, or near infrared drying. The drying temperature may be 60 to 120°C, 70 to 110°C, or 80 to 100°C. The drying time may be 1 to 60 minutes, 2 to 30 minutes, or 5 to 20 minutes.

[0110] The photosensitive element 1 may further include a protective film 30 on the photosensitive layer 20 to cover the photosensitive layer 20. The photosensitive element 1 may also have the protective film 30 laminated on the surface of the photosensitive layer 20 opposite to the surface that contacts the support film 10. The protective film 30 may be, for example, a polymer film such as polyethylene or polypropylene.

[0111] The range of the solid content of each component (components (A) to (G) and other components) other than the volatile substance in the photosensitive layer 20 may be the same as the range of the solid content of each component in the photosensitive resin composition.

[0112] [Printed Wiring Board] The printed wiring board according to this embodiment includes a permanent resist containing a cured product of the photosensitive resin composition according to this embodiment.

[0113] The method for producing a printed wiring board according to this embodiment includes the steps of forming a photosensitive layer on a substrate using the above-described photosensitive resin composition or photosensitive element, exposing and developing the photosensitive layer to form a resist pattern, and curing the resist pattern to form a permanent resist. An example of each step will be described below.

[0114] First, a substrate such as a copper-clad laminate is prepared, and a photosensitive layer is formed on the substrate. The photosensitive layer may be formed by applying a photosensitive resin composition to the substrate and drying it. Examples of methods for applying the photosensitive resin composition include screen printing, spraying, roll coating, curtain coating, and electrostatic coating. The drying temperature may be 60 to 120°C, 70 to 110°C, or 80 to 100°C. The drying time may be 1 to 60 minutes, 2 to 30 minutes, or 3 to 20 minutes.

[0115] The photosensitive layer may be formed on the substrate by peeling off the protective film from the photosensitive element and laminating the photosensitive layer on the substrate. Examples of methods for laminating the photosensitive layer include thermal lamination using a laminator.

[0116] Next, a negative film is brought into contact with the photosensitive layer directly or via a support film, and the layer is exposed to actinic rays. Examples of actinic rays include electron beams, ultraviolet rays, and X-rays, with ultraviolet rays being preferred. Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and halogen lamps. The exposure dose is 10 to 2000 mJ / cm. ２ , 100-1500mJ / cm ２ , or 300 to 1000 mJ / cm ２ may be.

[0117] After exposure, the unexposed areas are removed with a developer to form a resist pattern. Examples of the developing method include dipping and spraying. Examples of the developer that can be used include aqueous alkali solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, and tetramethylammonium hydroxide.

[0118] A patterned cured film (permanent resist) can be formed by subjecting the resist pattern to at least one of post-exposure and post-heating. The exposure dose of the post-exposure is 100 to 5000 mJ / cm. ２ , 500-2000mJ / cm ２ , or 700 to 1500 mJ / cm ２The heating temperature of the post-heating may be 100 to 200° C., 120 to 180° C., or 135 to 165° C. The heating time of the post-heating may be 5 minutes to 6 hours, 10 minutes to 3 hours, or 30 minutes to 2 hours.

[0119] The permanent resist may have vias with a diameter of 25 to 200 μm, or may have vias with a diameter of 25 to 100 μm. Even when such vias are formed in the permanent resist, by using the photosensitive resin composition according to this embodiment, vias with suppressed undercutting can be formed. Furthermore, the permanent resist may have both large vias with a diameter of 70 μm or more and small vias with a diameter of 35 μm or less. Even when vias with such different diameters are formed in the permanent resist, by using the photosensitive resin composition according to this embodiment, vias with suppressed undercutting can be formed for either diameter.

[0120] The permanent resist according to this embodiment can be used as an interlayer insulating layer or a surface protective layer of a semiconductor element. A semiconductor element having an interlayer insulating layer or a surface protective layer formed from a cured film of the above-described photosensitive resin composition, and an electronic device including the semiconductor element, can be produced. The semiconductor element may be, for example, a memory, a package, or the like having a multilayer wiring structure, a rewiring structure, or the like. Examples of electronic devices include mobile phones, smartphones, tablet terminals, personal computers, and hard disk suspensions. By providing a patterned cured film formed from the photosensitive resin composition according to this embodiment, semiconductor elements and electronic devices with excellent reliability can be provided.

[0121] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0122] (Synthesis Example 1) Bisphenol F novolac epoxy resin (manufactured by DIC Corporation, trade name "EXA-7376"; in formula (II), Y ３ and Y ４ is a glycidyl group, R １２350 parts by weight of bisphenol F novolac epoxy resin (epoxy equivalent: 186) having a structural unit in which ≡ is a hydrogen atom, 70 parts by weight of acrylic acid, 0.5 parts by weight of methylhydroquinone, and 120 parts by weight of carbitol acetate were mixed with stirring at 90°C. The mixed solution was cooled to 60°C, and 2 parts by weight of triphenylphosphine was added. The mixture was reacted at 100°C until the acid value of the solution reached 1 mgKOH / g or less. 98 parts by weight of tetrahydrophthalic anhydride (THPAC) and 85 parts by weight of carbitol acetate were added to the reaction solution, and the mixture was reacted at 80°C for 6 hours. The reaction solution was then cooled to room temperature to obtain a solution of acid-modified epoxy acrylate (A-1) (solids concentration: 73% by weight) as component (A).

[0123] The following materials were prepared as components (B) to (G): B-1: Tetramethylbisphenol F-type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., trade name "YSLV-80XY") C-1: Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA") D-1: 2-methyl-[4-(methylthio)phenyl]morpholino-1-propanone (manufactured by IGM Resins B.V., trade name "Omnirad 907") D-2: 4,4'-bis(diethylamino)benzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) E-1: Spherical silica filler (manufactured by Admatechs Co., Ltd., trade name "SC2050", methacrylsilane surface treated, average particle size: 0.5 μm) E-2: Spherical silica filler (manufactured by Admatechs Co., Ltd., trade name "SO-C1", methacrylsilane surface treated, average particle size: 0.3 μm) E-3: Spherical silica filler (manufactured by Admatechs Co., Ltd., trade name "YC100C", methacrylsilane surface treated, average particle size: 0.1 μm) F-1: 2,4-diethylthioxanthone (manufactured by IGM Resins B.V., trade name "Omnirad DETX") G-1: Phthalocyanine pigment (manufactured by Sanyo Dye Co., Ltd.)

[0124] Examples 1 to 6 and Comparative Examples 1 to 7 Photosensitive Resin Compositions Components were blended in the amounts (parts by mass, solid content equivalent) shown in Table 1 and kneaded using a three-roll mill. Carbitol acetate was then added so that the solid content concentration became 70% by mass, thereby preparing photosensitive resin compositions.

[0125] <Photosensitive Element> A 25 μm thick polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "G2-25") was prepared as a support film. A solution prepared by diluting a photosensitive resin composition with methyl ethyl ketone was applied onto the support film so that the thickness after drying would be 18 μm or 25 μm, and the coating was dried at 75°C for 15 minutes using a hot air convection dryer to form a photosensitive layer. Next, a polyethylene film (manufactured by Tamapoly Co., Ltd., product name "NF-15") was attached as a protective film to the surface of the photosensitive layer opposite the side in contact with the support film, thereby obtaining a photosensitive element.

[0126] [Evaluation of Resolution] The copper foil surface of a copper-clad laminate substrate (manufactured by Resonac Corporation, product name "MCL-E-679") in which a 12 μm thick copper foil was laminated on a glass epoxy substrate was treated with a roughening pretreatment solution (manufactured by MEC Co., Ltd., product name "CZ-8100"), followed by rinsing with water and drying to obtain a roughening pretreated copper-clad laminate substrate. Next, the protective film was peeled off from the photosensitive element, and the exposed photosensitive layer was placed so as to abut against the copper foil of the roughening pretreated copper-clad laminate substrate. The substrate was then laminated using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500") to obtain a laminate. The lamination conditions were a pressure of 0.4 MPa, a press hot plate temperature of 80°C, a vacuum evacuation time of 25 seconds, and a lamination press time of 25 seconds. After leaving the laminate at room temperature for at least 1 hour, the photosensitive layer was exposed to light using an i-line exposure device (manufactured by Ushio Inc., product name "UX-2240SM-XJ-01") at an exposure dose that would result in 13 fully cured steps in a 41-step tablet. A negative mask with a predetermined size opening pattern (opening diameter: 70 μm) was used as the exposure pattern. The support film was then peeled off from the photosensitive layer, and the layer was exposed to light using a 1% by mass aqueous solution of sodium carbonate for 60 seconds at a dose of 1.765 × 10 ５The developed photosensitive layer was then spray-developed at a pressure of 2000 mJ / cm using an ultraviolet exposure device, and the unexposed areas were dissolved and developed. ２ After that, the substrate was heated at 170°C for 1 hour to prepare a test specimen having a cured film (film thickness 18 µm or 25 µm) on which an opening pattern of a predetermined size was formed on a copper-clad laminate substrate.

[0127] The test piece was cast with an embedding resin (using Mitsubishi Chemical Corporation's trade name "jER828" as the epoxy resin and triethylenetetramine as the curing agent) and fully cured, and then polished with a polishing machine (Refine Tech Co., Ltd.'s trade name "Refine Polisher") to cut out the cross section of the opening pattern of the cured film. The cross section of the resulting opening pattern was observed using a metallurgical microscope and evaluated according to the following criteria. The results are shown in Table 1. If the evaluation result was S, A, or B, it was determined that the resolution was good. S: No undercut, and the via was straight. A: No undercut, and the via was tapered. B: Undercut, and the diameter of the undercut portion was less than the top diameter of the via + 5 μm. C: Undercut, and the diameter of the undercut portion was more than the top diameter of the via + 5 μm.

[0128] [Evaluation of Insulation Reliability] Test pieces were prepared in the same manner as in the above [Evaluation of Resolution], except that an evaluation substrate with interdigital electrodes (line / space = 10 μm / 10 μm) was used instead of a copper-clad laminate substrate, and the entire surface was exposed to light without using a negative mask. The test pieces were then exposed to light at 130°C, 85% RH, and 6 V for 250 hours. The resistance between the electrodes was measured, and the resistance was 10 －６ The time until the resistance reached Ω or less was defined as the copper migration occurrence time. The copper migration occurrence time was measured, and the interlayer insulation reliability (HAST resistance) was evaluated according to the following criteria. The results are shown in Table 1. If the evaluation result was A or B, it was determined that the insulation reliability was excellent. A: The migration occurrence time was 250 hours or more B: The migration occurrence time was 200 hours or more but less than 250 hours C: The migration occurrence time was less than 200 hours

[0129]

[0130] 1...photosensitive element, 10...support film, 20...photosensitive layer, 30...protective film

Claims

1. A photosensitive resin composition comprising (A) an acid-modified vinyl group-containing resin, (B) a thermosetting resin, (C) a photopolymerizable compound, (D) a photopolymerization initiator, and (E) an inorganic filler, wherein the (E) inorganic filler comprises a first inorganic filler having an average particle size of 0.5 μm or more and a second inorganic filler having an average particle size of 0.3 μm or less, and wherein the solids mass ratio of the content of the first inorganic filler to the content of the second inorganic filler is 6:4 to 8:

2.

2. The photosensitive resin composition according to claim 1, wherein the content of component (E) is 10 to 80 mass % based on the total solid content of the photosensitive resin composition.

3. The photosensitive resin composition according to claim 1, wherein the first inorganic filler and the second inorganic filler are both inorganic oxide fillers.

4. The photosensitive resin composition according to claim 1, wherein the first inorganic filler and the second inorganic filler are both spherical silica fillers.

5. The photosensitive resin composition according to claim 1, further comprising (F) a photosensitizer.

6. A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer comprises the photosensitive resin composition according to any one of claims 1 to 5.

7. A printed wiring board comprising a permanent resist containing a cured product of the photosensitive resin composition according to any one of claims 1 to 5.

8. A method for manufacturing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of claims 1 to 5; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form a permanent resist.

9. A method for manufacturing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to claim 6; exposing and developing the photosensitive layer to form a resist pattern; and hardening the resist pattern to form a permanent resist.

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