Photosensitive element, printed wiring board, and production method for printed wiring board

Abstract

A photosensitive element for a permanent resist according to the present disclosure comprises a support film and a photosensitive layer formed upon the support film, wherein: the photosensitive layer contains (A) a resin containing an acid-modified vinyl group, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) an inorganic filler; the (D) inorganic filler contains an inorganic filler having a refractive index of 1.500-1.700; the photosensitive layer has a thickness of 5-35 μm; and the photosensitive layer has an absorbance of 0.40-1.00 with respect to light having a wavelength of 380 nm.

Description

Photosensitive element, printed circuit board, and method for manufacturing a printed circuit board

[0001] This disclosure relates to a photosensitive element for permanent resist, a printed circuit board, and a method for manufacturing a printed circuit board.

[0002] In the field of printed circuit boards (PCBs), permanent resist is formed on the PCBs. Permanent resist plays a role in preventing corrosion of the conductor layer and maintaining electrical insulation between conductor layers during the use of the PCB. In recent years, permanent resist has also taken on the role of a solder resist film in processes such as flip-chip mounting and wire bonding mounting of semiconductor elements onto PCBs via solder, preventing solder from adhering to unwanted areas of the conductor layer on the PCB.

[0003] Permanent resists are produced, for example, by screen printing using a thermosetting resin composition, or by photographic methods using a photosensitive resin composition. Photosensitive resin compositions are also used in the form of photosensitive elements, which are formed by laminating layers (hereinafter also referred to as "photosensitive layers") made using the photosensitive resin composition onto a support film.

[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 semiconductor elements on the semiconductor package substrate via solder, (2) wire bond the semiconductor elements to the semiconductor package substrate, and (3) solder bond the semiconductor package substrate to a motherboard substrate. To form an image of the permanent resist, a photographic method is used in which a photosensitive resin composition is applied and dried, or the photosensitive layer of a photosensitive element is selectively irradiated with active light such as ultraviolet light to cure it, and only the unirradiated parts are removed by development to form an image. Because the photographic method is suitable for mass production due to its ease of work, it is widely used in the electronic materials industry for image formation of photosensitive materials (see, for example, Patent Document 1).

[0005] Japanese Patent Application Publication No. 11-240930

[0006] In response to the increasing density of printed circuit boards, further performance improvements are required for permanent resists. In particular, the demand for resolution is increasing year by year, and it is necessary to be able to reduce the diameter of via openings formed in the permanent resist. Furthermore, the demand for the shape of via openings is also increasing, and it is necessary to be able to form via openings with a good shape that suppresses undercuts on the sidewalls. If undercuts occur on the sidewalls, problems such as peeling or cracking of the permanent resist from the substrate circuit, or poor conductivity of the circuit are likely to occur.

[0007] Therefore, the present disclosure aims to provide a photosensitive element, a printed circuit board, and a method for manufacturing a printed circuit board that can form via openings with good resolution that can reduce the diameter of the via openings and suppress undercuts on the side walls.

[0008] One aspect of the present disclosure relates to the following photosensitive element, printed circuit board, and method for manufacturing a printed circuit board: [1] A photosensitive element for permanent resist, comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer contains (A) an acid-modified vinyl group-containing resin, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) an inorganic filler, wherein the (D) inorganic filler contains an inorganic filler having a refractive index of 1.500 to 1.700, the thickness of the photosensitive layer is 5 to 35 μm, and the absorbance of the photosensitive layer to light at a wavelength of 380 nm is 0.40 to 1.00. [2] The photosensitive element according to [1], wherein the content of the (D) inorganic filler in the photosensitive layer is 40 to 85% by mass based on the total amount of the photosensitive layer. [3] The photosensitive element according to [1] or [2] above, wherein the volume average particle size of the inorganic filler (D) is 0.1 to 1.5 μm. [4] The photosensitive element according to any one of [1] to [3] above, wherein the inorganic filler (D) includes composite particles of silica and a metal oxide other than silica. [5] The photosensitive element according to [4] above, wherein the composite particles include silica-titania composite particles. [6] The photosensitive element according to any one of [1] to [5] above, wherein the photosensitive layer further contains (E) an ultraviolet absorber. [7] The photosensitive element according to [6] above, wherein the content of the ultraviolet absorber (E) in the photosensitive layer is 0.05 to 3.0% by mass based on the total amount of the photosensitive layer. [8] The photosensitive element according to any one of [1] to [7] above, wherein the photosensitive layer further contains (F) a thermosetting resin. [9] A printed circuit board comprising a permanent resist containing a cured product of the photosensitive layer of the photosensitive element described in any of [1] to [8] above.

[10] A method for manufacturing a printed circuit board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element described in any of [1] to [8] above; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form a permanent resist.

[0009] According to this disclosure, it is possible to provide a photosensitive element, a printed circuit board, and a method for manufacturing a printed circuit board that can form via openings with good resolution that can reduce the diameter of the via openings and suppress undercuts on the side walls.

[0010] Figure 1 is a schematic cross-sectional view showing a photosensitive element according to this embodiment. Figure 2 is a schematic cross-sectional view showing a via opening formed in a permanent resist.

[0011] The following describes one embodiment of this disclosure in detail, but this disclosure is not limited thereto. In the following embodiment, the components (including elemental steps, etc.) are not essential unless they are clearly essential in principle, as specifically indicated. The same applies to numerical values ​​and their ranges, and this does not unduly limit this disclosure.

[0012] In this disclosure, the term "layer" includes not only structures that are formed across the entire surface when observed in a plan view, but also structures that are formed in only a portion of the surface. In this disclosure, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of that process is achieved.

[0013] In this disclosure, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one stage of the numerical range may be replaced with the upper or lower limit of another stage of the numerical range. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this disclosure, "A or B" means that either A or B is included, or both are included. Unless otherwise specified, the materials exemplified below may be used individually or in combination of two or more. In this disclosure, the content of each component in a composition means the total amount of multiple substances present in the composition if there are multiple substances corresponding to each component in the composition, unless otherwise specified.

[0014] In this disclosure, "solids" refers to the non-volatile components of a photosensitive resin composition, etc., excluding volatile substances such as water and diluents. It includes components that remain without evaporating or volatilizing when the resin composition, etc. is dried, and also includes components that are liquid, syrup-like, or waxy at room temperature (25°C, the same applies hereinafter).

[0015] [Photosensitive Element] The photosensitive element according to this embodiment comprises a support film and a photosensitive layer formed on the support film. In the photosensitive element according to this embodiment, the photosensitive layer contains (A) an acid-modified vinyl group-containing resin, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) an inorganic filler. In addition, in the photosensitive element according to this embodiment, the (D) inorganic filler includes an inorganic filler having a refractive index of 1.500 to 1.700, the thickness of the photosensitive layer is 5 to 35 μm, and the absorbance of the photosensitive layer for light with a wavelength of 380 nm is 0.40 to 1.00.

[0016] The photosensitive element according to this embodiment, by having a photosensitive layer containing the above components and having a thickness and absorbance within the above range, can achieve good resolution that allows for miniaturization of the via openings when forming a permanent resist having via openings, and can form via openings with suppressed sidewall undercuts. The inventors speculate that the reason for these effects is as follows: The above-mentioned specific inorganic filler has a refractive index close to that of the resin, so it can suppress light scattering at the interface between the resin and the inorganic filler. Therefore, when the photosensitive layer is exposed, light can easily penetrate to the bottom of the photosensitive layer, improving resolution and suppressing sidewall undercuts of the via openings. Furthermore, by keeping the thickness and absorbance of the photosensitive layer within the above range, it is possible to suppress hardening of the unexposed portion of the photosensitive layer due to scattered or reflected light while still allowing light to easily penetrate to the bottom of the photosensitive layer. Therefore, good resolution that allows for miniaturization of the via openings can be obtained while suppressing sidewall undercuts. Furthermore, according to the photosensitive element of this embodiment, by having the above configuration, it is possible to form a via opening with a good shape in which the taper angle of the side wall is close to 90° and does not exceed 95°.

[0017] In the photosensitive element according to this embodiment, the photosensitive layer is a negative photosensitive layer. The photosensitive layer can be formed, for example, using a photosensitive resin composition containing each of the above-described components. Hereinafter, each component contained in the photosensitive resin composition for forming the photosensitive layer will be described in detail.

[0018] <(A) component: acid-modified vinyl group-containing resin> The photosensitive resin composition according to this embodiment contains an acid-modified vinyl group-containing resin as the (A) component. The acid-modified vinyl group-containing resin is not particularly limited as long as it has a vinyl group which is a photopolymerizable ethylenically unsaturated bond and an alkali-soluble acidic group.

[0019] Examples of the group having an ethylenically unsaturated bond possessed by the (A) component 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 viewpoints of reactivity and resolution, the group having an ethylenically unsaturated bond may be a (meth)acryloyl group. Examples of the acidic group possessed by the (A) component include a carboxy group, a sulfo group, and a phenolic hydroxyl group. Among these, from the viewpoint of resolution, the acidic group may be a carboxy group.

[0020] The (A) component may be an acid-modified vinyl group-containing epoxy derivative obtained by reacting a resin (A') (hereinafter also referred to as the "(A') component") formed by reacting (a) an epoxy resin (hereinafter also referred to as the "(a) component") with (b) an ethylenically unsaturated group-containing organic acid (hereinafter also referred to as the "(b) component") with (c) a saturated group or an unsaturated group-containing polybasic acid anhydride (hereinafter also referred to as the "(c) component").

[0021] Examples of the acid-modified vinyl group-containing epoxy derivative include acid-modified epoxy (meth)acrylate. The acid-modified epoxy (meth)acrylate is a resin obtained by acid-modifying epoxy (meth)acrylate, which is a reaction product of component (a) and component (b), with component (c). As the acid-modified epoxy (meth)acrylate, for example, an addition reaction product obtained by adding a saturated or unsaturated polybasic acid anhydride to an esterified product obtained by reacting an epoxy resin with a vinyl group-containing monocarboxylic acid can be used.

[0022] (Epoxy resin (a)) Examples of component (a) include epoxy resins having an alicyclic skeleton, novolak-type epoxy resins, and bisphenol-type epoxy resins. Examples of the novolak-type epoxy resin include bisphenol novolak-type epoxy resins such as bisphenol A novolak-type epoxy resin, bisphenol F novolak-type epoxy resin, and bisphenol S novolak-type epoxy resin; phenol novolak-type epoxy resin, cresol novolak-type epoxy resin, biphenyl novolak-type epoxy resin, naphthol novolak-type epoxy resin, and the like. Examples of the bisphenol-type epoxy resin include bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol S-type epoxy resin.

[0023] From the viewpoints of crack resistance and resolution, component (a) may use an aromatic epoxy resin. The aromatic epoxy resin is an epoxy resin having an aromatic ring in the molecule. From the viewpoints of crack resistance and resolution, the aromatic epoxy resin preferably uses at least one selected from the group consisting of bisphenol F novolak-type epoxy resin, bisphenol F-type epoxy resin, phenol novolak-type epoxy resin, cresol novolak-type epoxy resin, and biphenyl-type epoxy resin, more preferably uses at least one selected from the group consisting of phenol novolak-type epoxy resin, cresol novolak-type epoxy resin, and biphenyl-type epoxy resin, and still more preferably uses at least one selected from the group consisting of cresol novolak-type epoxy resin and biphenyl-type epoxy resin.

[0024] (Organic acid containing ethylenically unsaturated groups (b)) Examples of component (b) include acrylic acid; acrylic acid derivatives such as acrylic acid dimers, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, and α-cyanocinnamic acid; semi-ester compounds which are reaction products of hydroxyl group-containing (meth)acrylates and dibasic acid anhydrides; and semi-ester compounds which are reaction products of vinyl group-containing monoglycidyl ethers or vinyl group-containing monoglycidyl esters and dibasic acid anhydrides. Component (b) can be used alone or in combination of two or more.

[0025] Semi-ester compounds 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.

[0026] 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, trimethylolpropanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and glycidyl (meth)acrylate.

[0027] 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.

[0028] Component (A'), obtained by reacting component (a) and component (b), has a hydroxyl group formed by a ring-opening addition reaction between the epoxy group of component (a) and the carboxyl group of component (b). By further reacting component (A') with component (c), an acid-modified vinyl group-containing epoxy resin is obtained in which the hydroxyl groups of component (A') (including the hydroxyl groups originally present in component (a)) and the acid anhydride group of component (c) are semi-esterified.

[0029] (Polybasic acid anhydride (c)) 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, from the viewpoint of resolution, component (c) may be tetrahydrophthalic anhydride. Component (c) may be used alone or in combination of two or more.

[0030] If necessary, as component (a), for example, a hydrogenated bisphenol A epoxy resin may be used in combination, or a styrene-maleic acid-based resin such as a hydroxyethyl (meth)acrylate modified product of a styrene-maleic anhydride copolymer may be used in combination.

[0031] (A) Component can be synthesized by known methods, but commercially available products may also be used. Specific examples of commercially available products include, for example, acid-modified cresol novolac type epoxy acrylates such as CCR-1291H, CCR-1235, CCR-1373H, and CCR-1374H (all manufactured by Nippon Kayaku Co., Ltd., trade names); acid-modified biphenyl type epoxy acrylates such as ZCR-1569H, ZCR-1601H, ZCR-1797H, and ZCR-1798H (all manufactured by Nippon Kayaku Co., Ltd., trade names); acid-modified bisphenol F type epoxy acrylates such as ZFR-1401H, ZFR-1491H, and ZFR-1533H (all manufactured by Nippon Kayaku Co., Ltd., trade names); and acid-modified bisphenol A type epoxy acrylates such as ZAR-1035 and ZAR-2000 (both manufactured by Nippon Kayaku Co., Ltd., trade names). These can be used individually or in combination of two or more types.

[0032] The acid value of component (A) may be 20 mg KOH / g or more, 30 mg KOH / g or more, 40 mg KOH / g or more, or 50 mg KOH / g or more, and may be 200 mg KOH / g or less, 180 mg KOH / g or less, 150 mg KOH / g or less, 100 mg KOH / g or less, 80 mg KOH / g or less, or 70 mg KOH / g or less. When the acid value of component (A) is 20 mg KOH / g or more, the photosensitive resin composition tends to have excellent solubility in dilute alkaline solutions. When the acid value of component (A) is 200 mg KOH / g or less, the electrical properties of the permanent resist tend to be improved. Two or more components (A) with different acid values ​​may be used in combination, in which case it is preferable that the weighted average acid value of the acid values ​​of the two or more components (A) be within any of the above ranges.

[0033] The acid value can be measured using the following procedure. First, 1 g of component (A), which is the substance to be measured for acid value, is accurately weighed, and then 30 g of acetone is added to component (A) to uniformly dissolve it and obtain a solution. Next, an appropriate amount of phenolphthalein, which is an indicator, is added to the solution, and then titration is performed using a 0.1 N KOH (potassium hydroxide) aqueous solution. The acid value is determined by calculating the mass (in mg) of KOH required to neutralize the acetone solution of component (A).

[0034] (A) The weight-average molecular weight (Mw) of component is not particularly limited, but may be 600 or more, 800 or more, 1000 or more, 3000 or more, 4000 or more, or 5000 or more, from the viewpoint of resolution, adhesion, heat resistance, and insulation reliability, and may be 30000 or less, 25000 or less, 18000 or less, 15000 or less, or 10000 or less.

[0035] Mw can be measured by gel permeation chromatography (GPC). For example, Mw can be measured under the GPC conditions described below, and the value converted using a calibration curve for standard polystyrene can be used as the Mw value. A set of five samples ("PStQuick MP-H" and "PStQuick B," manufactured by Tosoh Corporation) can be used as the standard polystyrene to create the calibration curve. GPC instrument: High-speed GPC instrument "HCL-8320GPC" (manufactured by Tosoh Corporation) Detector: Differential refractometer or UV detector (manufactured by Tosoh Corporation) Column: TSKgel SuperMultipore HZ-H column (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 / THF 5 mL Injection volume: 20 μL

[0036] (A) The content of component (A) may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total solid content of the photosensitive resin composition, from the viewpoint of the heat resistance, electrical properties and chemical resistance of the permanent resist, and may also be 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less.

[0037] <Component (B): Photopolymerizable compound> The photosensitive resin composition according to this embodiment contains a photopolymerizable compound (excluding component (A) described above) as component (B). Component (B) is not particularly limited as long as it is a compound having a functional group that exhibits photopolymerizability. Examples of functional groups that exhibit photopolymerizability include groups having an ethylenically unsaturated bond, such as vinyl group, allyl group, propargyl group, butenyl group, ethynyl group, phenylethynyl group, maleimide group, nadiimide group, and (meth)acryloyl group.

[0038] (B) Component examples include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; mono- or di(meth)acrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, and polyethylene glycol; (meth)acrylamide compounds such as N,N-dimethyl(meth)acrylamide and N-methylol(meth)acrylamide; aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate; hexanediol, trimethylolpropane, pentaerythritol, and ditrimethylolpropane. Examples include polyhydric alcohols such as dipentaerythritol and tris-hydroxyethyl isocyanurate, or polyhydric (meth)acrylates of ethylene oxide or propylene oxide adducts thereof; (meth)acrylate compounds of ethylene oxide or propylene oxide adducts of phenolic compounds such as phenoxyethyl (meth)acrylate and polyethoxydi(meth)acrylate of bisphenol A; (meth)acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and melamine (meth)acrylate. Component (B) can be used individually or in combination of two or more.

[0039] From the viewpoint of insulation reliability, component (B) may include a (meth)acrylic compound having (meth)acryloyl groups. The (meth)acrylic compound may be a monofunctional (meth)acrylic compound or a polyfunctional (meth)acrylic compound. A "monofunctional (meth)acrylic compound" means a compound in which the total number of acryloyl groups and methacryloyl groups in one molecule is 1, and a "polyfunctional (meth)acrylic compound" means a compound in which the total number of acryloyl groups and methacryloyl groups in one molecule is 2 or more. From the viewpoint of superior insulation reliability, the (meth)acrylic compound may include a (meth)acrylic compound with four or more functions. Examples of (meth)acrylic compounds with four or more functions include pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, and propoxylated dipentaerythritol hexa(meth)acrylate. These can be used individually or in combination of two or more.

[0040] The content of component (B) may be 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, or 3.5% by mass or more, based on the total amount of solids in the photosensitive resin composition, and may also be 7.0% by mass or less, 6.0% by mass or less, 5.0% by mass or less, or 4.5% by mass or less.

[0041] <Component (C): Photopolymerization Initiator> The photosensitive resin composition according to this embodiment contains a photopolymerization initiator as component (C). Component (C) is not particularly limited as long as it can polymerize components (A) and (B). Component (C) may be used alone or in combination of two or more types.

[0042] (C) Component includes, for example, acetophenone compounds such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, N,N-dimethylaminoacetophenone; 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2-amylanthraquinone, 2-amylanthraquinone Examples include anthraquinone compounds such as noanthraquinone; 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-benzoyl oxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone-1-(O-acetyl oxime), and 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl) oxime].

[0043] The content of component (C) is not particularly limited, but may be 0.20 to 10% by mass, 0.25 to 5% by mass, or 0.30 to 1% by mass, based on the total solid content of the photosensitive resin composition.

[0044] <(D) Component: Inorganic Filler> From the viewpoints of low coefficient of thermal expansion, heat resistance, and flame retardancy, the photosensitive resin composition according to this embodiment further contains an inorganic filler as the (D) component. Also, from the viewpoint that the (D) component can reduce the diameter of via openings, suppress undercuts on sidewalls, and form via openings with a good shape having a taper angle close to 90°, the (D) component includes an inorganic filler having a refractive index of 1.500 to 1.700. The (D) component may be an uncoated filler or a surface-treated filler. The surface-treated filler can be obtained by treating the surface of the inorganic filler with a surface treatment agent. The (D) component may be used alone or in combination of two or more kinds.

[0045] The (D) component is not particularly limited. For example, silica (SiO ２ ), alumina (Al ２ O ３ ), titania (TiO ２ ), tantalum oxide (Ta ２ O ５ ), zirconia (ZrO ２ ), silicon nitride (Si ３ N ４ ), barium titanate (BaO·TiO ２ ), barium carbonate (BaCO ３ ), magnesium carbonate (MgCO ３ ), aluminum hydroxide (Al(OH) ３ ), magnesium hydroxide (Mg(OH) ２ ), lead titanate (PbO·TiO ２ ), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), gallium oxide (Ga ２ O ３ ), spinel (MgO·Al ２ O ３ ), mullite (3Al ２ O ３ ·2SiO ２ ), cordierite (2MgO·2Al ２ O ３ / 5SiO ２ ), talc (3MgO·4SiO ２ ·H ２O), aluminum titanate (TiO ２ Al ２ O ３ ), yttria-containing zirconia (Y ２ O ３ ・ZrO ２ ), barium silicate (BaO・8SiO ２ ), boron nitride (BN), calcium carbonate (CaCO3) ３ ), barium sulfate (BaSO ４ ), calcium sulfate (CaSO4) ４ ), zinc oxide (ZnO), magnesium titanate (MgO・TiO ２ Examples include hydrotalcite, mica, calcined kaolin, and carbon (C).

[0046] From the viewpoint of achieving superior resolution, composite particles of two or more metal oxides may be used as component (D). Examples of such composite particles include composite particles of silica and a metal oxide other than silica (hereinafter also referred to as "component (D1)").

[0047] Examples of metal oxides other than silica that constitute component (D1) include titania, zirconia, alumina, boron oxide, calcium oxide, yttria, nickel oxide, hafnium oxide, niobium oxide, tantalum oxide, and zinc oxide. Among these, from the viewpoint of superior resolution, the metal oxide other than silica may be titania. In other words, component (D1) may be silica-titania composite particles.

[0048] The volume-average particle size of component (D) is not particularly limited, but may be 0.01 to 20 μm, 0.1 to 10 μm, 0.1 to 1.5 μm, 0.1 to 1.2 μm, 0.2 to 1.0 μm, or 0.25 to 0.7 μm. The volume-average particle size of component (D) is the average particle size when dispersed in the photosensitive resin composition, and is a value obtained by measuring it using the following procedure.

[0049] After diluting the photosensitive resin composition 1000 times with a solvent (methyl ethyl ketone), the particle size distribution of the particles dispersed in the solvent is measured using a submicron particle analyzer (Beckman Coulter, Inc., product name: N5) in accordance with the international standard ISO 13321, with a refractive index of 1.38. The particle diameter at 50% of the cumulative value (by volume) in the particle size distribution is defined as the volume-average particle diameter. Component (D) contained in the photosensitive layer formed using the photosensitive resin composition can also be measured using the same procedure.

[0050] The refractive index of component (D) is not particularly limited, but may be 1.500 to 1.700, 1.520 to 1.680, 1.530 to 1.640, or 1.535 to 1.600. The refractive index can be measured, for example, by the immersion method in the following procedure. First, solvents with different refractive indices (1-bromonaphthalene, liquid paraffin) are mixed in any proportion to prepare several mixed solvents with different refractive indices. Next, an inorganic filler is added to each mixed solvent to prepare a dispersion. The transparency of the dispersions is visually compared, and the refractive index of the mixed solvent used for the most transparent dispersion is taken as the refractive index of the inorganic filler. Component (D) must contain at least an inorganic filler whose refractive index is within the above range, but may further contain an inorganic filler whose refractive index is outside the above range. From the viewpoint of being able to make the via opening smaller in diameter, suppress undercutting of the side wall, and form a via opening with a good shape that has a taper angle closer to 90°, the content of inorganic filler with a refractive index within the above range may be 50% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of component (D).

[0051] (D) The shape of component can be spherical, crushed, or the like. Among these, a spherical shape is preferred from the viewpoint of suppressing the diffusion of energy rays incident on the photosensitive layer containing the photosensitive resin composition during exposure and improving resolution. Here, "spherical" means that the circularity calculated by the following formula using the area and perimeter measured from the photograph of the target particle is 90 or more. Circularity = {4π × (area) ÷ (perimeter)} ２} × 100

[0052] Particles can be observed, for example, using a scanning electron microscope (SEM) at 5000x magnification, and the average area and average perimeter of any 10 particles can be used as the area and perimeter values ​​in the above formula, respectively.

[0053] The content of component (D) may be 40% by mass or more, 50% by mass or more, 55% by mass or more, or 60% by mass or more, based on the total solid content of the photosensitive resin composition, and may also be 85% by mass or less, 80% by mass or less, or 70% by mass or less.

[0054] <Component (E): UV absorber> The photosensitive resin composition according to this embodiment may contain a UV absorber as component (E) from the viewpoint of easily adjusting the absorbance of the photosensitive layer to within the range of 0.40 to 1.00 and further reducing the diameter of the via opening.

[0055] Component (E) may be a compound that absorbs light in the range of 340 to 430 nm, or a compound that efficiently absorbs light at a wavelength of 365 nm. The molar extinction coefficient of component (E) for light at a wavelength of 365 nm may be in the range of 500 to 50,000 L / (mol·cm). The molar extinction coefficient is an indicator of how easily light is absorbed.

[0056] When the photosensitive layer is exposed using active light in the 340-430 nm range, component (E) effectively absorbs light of the exposure wavelength and may contain at least one selected from the group consisting of benzophenone compounds, benzotriazole compounds, and triazine compounds, and may contain a benzophenone compound. The benzophenone compound may be a benzophenone compound in which some of the hydrogen atoms are substituted with a group having oxygen atoms, or a benzophenone compound having a hydroxyl group.

[0057] Examples of benzophenone compounds include 4,4'-dimethoxybenzophenone, 4,4'-bis(trimethylacetoxy)benzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-(octyloxy)benzophenone, and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid. Examples of benzotriazole compounds include 2,2-methylenebis[6-(2H-benzotriazole-2-yl)-4-tert-octylphenol], 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole, 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol, and 2-(5-chloro-2H-benzotriazole-2-yl)-6-tert-butyl-4-methylphenol. Examples of triazine compounds include 2-[4,6-di(2,4-xylyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol, and 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine.

[0058] The content of component (E) may be 0.03 to 3.0% by mass, 0.05 to 2.0% by mass, 0.08 to 1.5% by mass, or 0.1 to 1.0% by mass, based on the total solid content of the photosensitive resin composition, from the viewpoint of easily adjusting the absorbance of the photosensitive layer to within the range of 0.40 to 1.00 and further reducing the diameter of the via opening.

[0059] <Component (F): Thermosetting resin> The photosensitive resin composition according to this embodiment may further contain a thermosetting resin as component (F) from the viewpoint of heat resistance, adhesion, and insulation reliability of the formed cured film (permanent resist). Component (F) may be used alone or in combination of two or more types.

[0060] Examples of component (F) include epoxy resin, phenolic resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene resin, silicone resin, triazine resin, and melamine resin. Among these, epoxy resin may be used as component (F) from the viewpoint of superior heat resistance, adhesion, and insulation reliability.

[0061] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, hydantoin type epoxy resin, triglycidyl isocyanurate, and bixylenol type epoxy resin.

[0062] Component (F) may include, from the viewpoint of developability and insulation reliability, a first polyfunctional epoxy resin (F1) with a molecular weight of less than 380 (hereinafter also referred to as "component (F1)") and a second polyfunctional epoxy resin (F2) with a molecular weight of 380 or more (hereinafter also referred to as "component (F2)"). Component (F1) may be used alone or in combination of two or more types. Component (F2) may be used alone or in combination of two or more types.

[0063] The molecular weight of component (F1) may be 100 or more and less than 380, or 200 or more and less than 380, and the molecular weight of component (F2) may be 380 to 1200, or 380 to 500.

[0064] The content of components (F1) and (F2) in component (F) is not particularly limited, but from the viewpoint of developability, the mass ratio of the content of component (F1) to the content of component (F2) (content of component (F1) / content of component (F2)) may be 1.0 to 5.0, 2.0 to 4.5, 3.0 to 4.0, or 3.5 to 4.0.

[0065] The content of component (F) may be 2 to 30% by mass, 5 to 25% by mass, or 8 to 20% by mass, based on the total solid content of the photosensitive resin composition. When the content of component (F) is within the above range, the heat resistance of the formed cured film can be further improved while maintaining good developability.

[0066] <Component (G): Photosensitizer> The photosensitive resin composition of this embodiment may further contain a photosensitizer as component (G). By containing component (G) in the photosensitive resin composition, the absorption wavelength of the active light used for exposure can be effectively utilized.

[0067] (G) Examples of components include benzophenone compounds such as 4,4'-bis(diethylamino)benzophenone; 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; pyrarisone compounds; oxazole compounds; thiazole compounds, benzoxazole compounds; thiazole compounds; triazole compounds; stilbene compounds; triazine compounds; thiophene compounds; naphthalimide compounds; and triarylamine compounds.

[0068] From the viewpoint of maintaining a good via shape, component (G) may be at least one selected from 2,4-dimethylthioxanthone and 2,4-diethylthioxanthone.

[0069] The content of component (G) may be 0.01 to 5.0% by mass, 0.02 to 3.0% by mass, 0.03 to 1.0% by mass, 0.04 to 0.5% by mass, or 0.05 to 0.35% by mass, based on the total solid content of the photosensitive resin composition.

[0070] <Component (H): Coupling agent> The photosensitive resin composition according to this embodiment may further contain a coupling agent as component (H). Component (H) may be used alone or in combination of two or more types.

[0071] Component (H) is not particularly limited, but a silane coupling agent may be used. Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatetopropyltriethoxysilane.

[0072] The content of component (H) may be 0.01 to 5.0% by mass, 0.03 to 3.0% by mass, or 0.05 to 2.0% by mass, based on the total amount of solids in the photosensitive resin composition.

[0073] <Component (I): Pigment> The photosensitive resin composition according to this embodiment may further contain a pigment as component (I) from the viewpoint of improving the identifiability or appearance of the manufacturing apparatus. As component (I), a coloring agent that produces a desired color when concealing wiring (conductor patterns) can be used. Component (I) may be used alone or in combination of two or more types.

[0074] (I) Examples of components include phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, carbon black, and naphthalene black.

[0075] (I) The content of component (I) may be 0.01 to 5.0% by mass, 0.03 to 3.0% by mass, or 0.05 to 2.0% by mass, based on the total amount of solids in the photosensitive resin composition, from the viewpoint of making the manufacturing equipment easier to identify and better concealing the wiring.

[0076] <Component (J): Polymerization Inhibitor> The photosensitive resin composition may further contain a polymerization inhibitor as component (J) from the viewpoint of suppressing polymerization in unexposed areas during resist pattern formation and further improving resolution. Examples of component (J) include catechol compounds (e.g., tert-butylcatechol such as 4-tert-butylcatechol) and hindered amines (e.g., 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl).

[0077] The content of component (J) may be 0.01% by mass or more, 0.03% by mass or more, or 0.05% by mass or more, based on the total amount of components (A) and (B), and may be 5.0% by mass or less, 3.0% by mass or less, 1.0% by mass or less, 0.50% by mass or less, or 0.10% by mass or less.

[0078] <Other Components> The photosensitive resin composition according to this embodiment may be further mixed with various additives as needed. Examples of additives include curing accelerators such as melamine; thickeners such as bentonite and montmorillonite; defoaming agents such as silicone-based, fluorine-based, and vinyl resin-based agents; and flame retardants such as phosphorus-based phosphate compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters. These may be used individually or in combination of two or more.

[0079] The photosensitive resin composition according to this embodiment may or may not contain a thermoplastic elastomer, but when a thermoplastic elastomer is included, sensitivity and resolution tend to decrease. Therefore, the content of the thermoplastic elastomer in the photosensitive resin composition may be 5% by mass or less, 1% by mass or less, 0.1% by mass or less, or 0% by mass, based on the total solid content of the photosensitive resin composition.

[0080] The photosensitive resin composition according to this embodiment may be mixed with a diluent such as an organic solvent to adjust its viscosity. Examples of organic solvents 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.

[0081] When a diluent is used, the content of the diluent in the photosensitive resin composition may be 10 to 50% by mass, 20 to 40% by mass, or 25 to 35% by mass. By setting the content of the diluent within the above ranges, the coatability of the photosensitive resin composition can be improved.

[0082] The photosensitive resin composition according to this embodiment can be prepared by uniformly mixing the above-mentioned components using a roll mill, bead mill, or the like.

[0083] Figure 1 is a schematic cross-sectional view showing a photosensitive element according to this embodiment. As shown in Figure 1, the photosensitive element 1 comprises a support film 10 and a photosensitive layer 20 formed on the support film 10. The solid content of each component other than volatile substances in the photosensitive layer 20 may be within the numerical range of the solid content of each component in the photosensitive resin composition described above.

[0084] The photosensitive element 1 can be manufactured, for example, by applying the photosensitive resin composition according to this embodiment onto the support film 10 using 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.

[0085] Examples of support films 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, 10 to 50 μm, 15 to 40 μm, or 20 to 30 μm.

[0086] The coating film can be dried using hot air drying, far-infrared radiation, or near-infrared radiation. The drying temperature may be 60-120°C, 70-110°C, or 80-100°C. The drying time may be 1-60 minutes, 2-30 minutes, or 3-20 minutes.

[0087] A protective film 30 covering the photosensitive layer 20 may be further provided on the photosensitive layer 20. The protective film 30 of the photosensitive element 1 can also be laminated on the side of the photosensitive layer 20 opposite to the side in contact with the support film 10. As the protective film 30, for example, a polymer film such as polyethylene or polypropylene may be used. The protective film may be the same film as the support film, or it may be a different film.

[0088] In the photosensitive element according to this embodiment, the thickness of the photosensitive layer 20 is 5 to 35 μm. The thickness of the photosensitive layer 20 may be 8 to 32 μm, 10 to 30 μm, 12 to 25 μm, or 15 to 20 μm, from the viewpoint of being able to make the via opening smaller in diameter, further suppress undercutting of the side wall, and form a via opening with a good shape that has a taper angle closer to 90°.

[0089] In the photosensitive element according to this embodiment, the absorbance of the photosensitive layer 20 for light with a wavelength of 380 nm is 0.40 to 1.00. The absorbance of the photosensitive layer 20 for light with a wavelength of 380 nm may be 0.50 to 0.99, 0.55 to 0.98, or 0.60 to 0.96, from the viewpoint of being able to make the via opening smaller in diameter, further suppress undercutting of the side wall, and form a via opening with a good shape that has a taper angle closer to 90°.

[0090] The absorbance of the photosensitive layer 20 for light at a wavelength of 380 nm can be measured using, for example, an ultraviolet-visible spectrophotometer such as the U-3310 spectrophotometer (manufactured by Hitachi High-Tech Science Corporation), or a spectroscopic haze meter such as the SH7000 spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., measurement wavelength 380 to 780 nm).

[0091] In the photosensitive element according to this embodiment, the refractive index of the cured photosensitive layer may be 1.550 or higher. When the refractive index of the cured layer is 1.550 or higher, the photosensitive layer exhibits excellent resolution. The reason for this is not entirely clear, but it is presumed that when the refractive index of the cured layer is 1.550 or higher, the diffusion of energy rays incident on the photosensitive layer during exposure is suppressed, and the hardening of the light-shielding portion is suppressed. From a similar viewpoint, the refractive index of the cured photosensitive layer is preferably 1.550 to 1.680, more preferably 1.550 to 1.640, and even more preferably 1.550 to 1.600.

[0092] The refractive index of the cured photosensitive layer can be measured, for example, by the following method. First, a photosensitive layer is formed on a silicon wafer using a photosensitive element. Then, the photosensitive layer is exposed to 200 mJ / cm using a parallel light exposure machine (manufactured by Oak Manufacturing Co., Ltd., product name "EXM-1201") with an ultra-high pressure mercury lamp as the light source. ２ The entire surface is exposed. Exposure may also be performed from above the support film. In this case, the support film is peeled off and removed after exposure. Next, a matching solution is applied to the surface of the cured photosensitive layer, and the refractive index of the cured photosensitive layer on the silicon wafer is measured under the following conditions while in close contact with the prism. • Measurement device: Model 2010 / M PRISM COUPLER, manufactured by Metron Corporation • Wavelength: 632.8 nm • Measurement temperature: 25°C • Measurement atmosphere: Air • Matching solution: IMMERSION LIQUID (nD=1.640), manufactured by Cargile Laboratories Inc.

[0093] [Printed Wiring Board] The printed wiring board according to this embodiment comprises a permanent resist including a cured product of the photosensitive layer in the photosensitive element according to this embodiment.

[0094] The method for manufacturing a printed circuit board according to this embodiment comprises the steps of: forming a photosensitive layer on a substrate using the above-described photosensitive element; forming a resist pattern by exposing and developing the photosensitive layer; and forming a permanent resist by curing the resist pattern. An example of each step will be described below.

[0095] First, a metal-clad laminate, such as a copper-clad laminate, is prepared as the substrate, and a photosensitive layer is formed on the substrate. In this case, for example, the photosensitive layer can be formed by thermal laminating the photosensitive layer of the photosensitive element onto the substrate using a laminator.

[0096] Next, by irradiating at least a portion of the photosensitive layer with active light, the irradiated portion becomes photocured, and a latent image is formed. In this case, if a support is present on the photosensitive layer, if the support is transparent to the active light, the active light can be irradiated through the support. However, if the support is light-blocking, the support is removed before irradiating the photosensitive layer with active light.

[0097] Exposure methods include, for example, direct imaging exposure methods such as LDI (Laser Direct Imaging) exposure and DLP (Digital Light Processing) exposure, which involve irradiating an active ray in an image-like manner; methods of irradiating an active ray in an image-like manner via a negative mask pattern (mask exposure method); and methods of irradiating an active ray in an image-like manner via projection exposure. Examples of active rays include electron beams, ultraviolet rays, and X-rays. 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 / cm². ２ Or 100-1500 mJ / cm ２ That's fine.

[0098] After exposure, the unexposed areas are dissolved and removed with a developer to form a resist pattern. Development methods include, for example, dipping and spraying. Suitable developers include alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, and tetramethylammonium hydroxide.

[0099] Next, the formed resist pattern can be sufficiently cured by at least one of post-exposure and post-heating to form a permanent resist. The exposure dose for post-exposure is 100 to 5000 mJ / cm². ２ , 500-2000mJ / cm ２ , or 700-1500 mJ / cm² ２ The heating temperature for post-heating may be 100-200°C, 120-180°C, or 135-165°C. The heating time for post-heating may be 5 minutes to 6 hours, 10 minutes to 3 hours, or 30 minutes to 2 hours. The thickness of the permanent resist may be 10-50 μm, 15-40 μm, or 20-30 μm.

[0100] The permanent resist according to this embodiment can be used as an interlayer insulating layer or surface protective layer of a semiconductor element. A semiconductor element having an interlayer insulating layer or surface protective layer formed from the cured film of the photosensitive layer described above, and an electronic device including the semiconductor element, can be manufactured. The semiconductor element may be, for example, a memory, package, etc., having a multilayer wiring structure, a rewiring structure, etc. Examples of electronic devices include mobile phones, smartphones, tablet terminals, personal computers, and hard disk suspensions.

[0101] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0102] <Examples 1-16 and Comparative Examples 1-7> [Photosensitive Resin Composition] Each component was blended in the amounts (parts by mass, equivalent to solid content) shown in Tables 1-4 below and kneaded in a three-roll mill. Then, methyl ethyl ketone was added to obtain a photosensitive resin composition so that the solid content concentration was 65% by mass. Details of each component shown in Tables 1-4 are as follows.

[0103] ((A) Acid-modified vinyl group-containing resin) A-1: ​​Acid-modified cresol novolac epoxy acrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "CCR-1374H", acid value: 60 mg KOH / g, Mw: 6000-7000) ((B) Photopolymerizable compound) B-1: KAYARAD DPHA (mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, manufactured by Nippon Kayaku Co., Ltd., trade name) ((C) Photopolymerization initiator) C-1: 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (manufactured by IGM Resins B.V., trade name "Omnirad 907", α-aminoacetophenone-based photopolymerization initiator) ((D) Inorganic filler) D-1: Silica-titania composite particles (volume average particle diameter: 300 nm, refractive index: 1.542, shape: spherical) D-2: Magnesium hydroxide particles (manufactured by Kamishima Chemical Industry Co., Ltd., product name "V-6", average particle diameter: 1.2 μm, refractive index: 1.56, shape: polyhedral) D-3: Synthetic boehmite particles (manufactured by Kamishima Chemical Industry Co., Ltd., product name "Alcube", average particle diameter: 1.0 μm, refractive index: 1.67, shape: cubic) D-4: Silica particles (manufactured by Denka Co., Ltd., product name "SFP-20M", average particle diameter: 0.3 μm, refractive index: 1.46, shape: spherical) D-5: Alumina filler (manufactured by Sumitomo Chemical Co., Ltd., product name "Advanced Alumina AA-04", average particle diameter: 0.47 μm, refractive index: 1.76, shape: polyhedral sphere) ((E) UV absorber) E-1: Dihydroxybenzophenone-based UV absorber (manufactured by BASF Corporation, product name "Uvinul 3050") E-2: 2,4,6-Tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,E-3: 5-triazine (manufactured by ADEKA Corporation, triazine-based UV absorber, product name "LA-F70") E-4: Triazine-based UV absorber (manufactured by Chemipro Chemicals Co., Ltd., product name "KEMISORB 111") E-5: Benzotriazole-based UV absorber (manufactured by BASF Japan Ltd., product name "Tinuvin 477") E-6: Benzotriazole-based UV absorber (manufactured by BASF Japan Ltd., product name "Tinuvin 384-2") ((F) Thermosetting resins) F-1: Bisphenol F type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., product name "YSLV-80XY", first polyfunctional epoxy resin, molecular weight 300 or more and less than 380) F-2: Phenol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name "RE-306", second polyfunctional epoxy resin, molecular weight 380 to 1200) ((G) Photosensitizer) G-1: 4,4'-bis(diethylamino)benzophenone G-2: 2,4-diethylthioxanthone ((H) Coupling agent) H-1: 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-503") ((I) Pigment) I-1: Mixture of blue pigment and yellow pigment ((J) Polymerization inhibitor) J-1: 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl

[0104] The refractive index of the inorganic filler was measured by immersion using the following procedure. First, solvents with different refractive indices (1-bromonaphthalene and liquid paraffin) were mixed in arbitrary proportions to prepare multiple mixed solvents with different refractive indices. Next, the inorganic filler was added to each mixed solvent to prepare a dispersion. The transparency of the dispersions was visually compared, and the refractive index of the mixed solvent used for the most transparent dispersion was taken as the refractive index of the inorganic filler.

[0105] [Photosensitive Element] A polyethylene terephthalate film with a thickness of 25 μm (manufactured by Toyobo Co., Ltd., product name: HPES0) was prepared as a support film. The photosensitive resin composition was applied to the support film so that the thickness after drying was as shown in Tables 1 to 4, and dried at 100°C for 10 minutes using a hot air convection dryer to form a photosensitive layer. Next, a polyethylene film (manufactured by Tamapoly Co., Ltd., product name: NF-13) was laminated as a protective film onto the surface opposite to the side of the photosensitive layer that is in contact with the support film to obtain a photosensitive element.

[0106] [Evaluation] (1-1) Measurement of absorbance of the photosensitive layer The absorbance of the photosensitive layer in the photosensitive elements prepared in each example and comparative example was measured by the following method. After peeling the protective film off the photosensitive element, light was irradiated from the support film side using a spectroscopic haze meter SH7000 (manufactured by Nippon Denshoku Industries Co., Ltd., measurement wavelength 380-780 nm), and the absorbance of the photosensitive layer to light at a wavelength of 380 nm was measured. The results are shown in Tables 1 to 4.

[0107] (1-2) Preparation of evaluation laminates A printed circuit board substrate (manufactured by Resonac Co., Ltd., product name "MCL-E-679"), in which 12 μm thick copper foil was laminated on a glass epoxy substrate, was treated with a roughening solution (manufactured by MEC Co., Ltd., product name "CZ-8100") on the copper foil surface, then washed with water and dried to obtain a roughened printed circuit board substrate. Next, the protective film was peeled off from the photosensitive elements prepared in each example and comparative example, and the exposed photosensitive layer was placed in contact with the copper foil of the roughened printed circuit board substrate. Then, lamination was performed using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500"). The lamination conditions were: vacuuming time 20 seconds, atmospheric pressure 4 kPa or less, press hot plate temperature 70°C, pressing pressure 0.4 MPa, and lamination press time 30 seconds. After lamination, the substrate was left at room temperature for more than one hour to obtain an evaluation laminate in which a photosensitive layer and a support film were laminated in that order on the copper foil surface of a printed circuit board substrate.

[0108] (1-3) Sensitivity Measurement of the Photosensitive Layer A 41-step tablet (manufactured by Resonac Corporation) was placed on the support film of the evaluation laminate obtained in (1-2) above, and exposure was performed using an i-line exposure apparatus (manufactured by Ushio Inc., product name "UX-2240SM"). After exposure, the material was left at room temperature for 30 minutes, then the support film was peeled off, and the photosensitive layer was spray-developed for 40 seconds using a 1% by mass sodium carbonate aqueous solution at 30°C to remove unexposed areas. Exposure energy was 100 to 1000 mJ / cm². ２ Within the range of 25 mJ / cm ２ The above test was performed while gradually changing the exposure energy, and the amount of exposure energy that resulted in 10.0 remaining steps on the 41-step tablet after development was used to determine the sensitivity of the photosensitive layer (unit: mJ / cm²). ２ )

[0109] (1-4) Evaluation of via resolution The support film of the evaluation laminate obtained in (1-2) above was exposed using an i-line exposure apparatus (Ushio Inc., product name "UX-2240SM"). The exposure pattern used was a negative mask with an aperture pattern of a predetermined size (aperture pattern with aperture diameter size from 10 to 60 μm in 1 μm increments). Exposure was performed at an exposure energy amount that resulted in a sensitivity of the photosensitive layer, i.e., a remaining step stage of 10.0, as measured in (1-3) above. After exposure, the sample was left at room temperature for 30 minutes, then the support film was peeled off, and the photosensitive layer was spray-developed for 40 seconds using a 1% by mass aqueous sodium carbonate solution at 30°C to remove unexposed areas. After development, a total of 2000 mJ / cm² was applied using an ultraviolet exposure apparatus. ２Post-exposure was performed. The via pattern of the obtained cured film (permanent resist) was observed using an optical microscope, and the resolution was evaluated based on the minimum diameter of the mask through which the vias opened. Here, the state in which the vias are "open" refers to the state in which the copper foil of the printed circuit board substrate can be seen when the via opening is observed from directly above using an optical microscope. The smaller this value, the better the resolution. Based on the obtained values, the resolution was evaluated according to the following criteria. If the evaluation result is A, B, or C, it is judged that the resolution is good. The results are shown in Tables 1 to 4. A: The minimum diameter of the mask through which the vias open is less than 20 μm. B: The minimum diameter of the mask through which the vias open is 20 μm or more and less than 25 μm. C: The minimum diameter of the mask through which the vias open is 25 μm or more and less than 30 μm. D: The minimum diameter of the mask through which the vias open is 30 μm or more.

[0110] (1-5) Evaluation of the shape of the via openings Test specimens with via openings formed according to the minimum opening mask diameter pattern from the via openings formed in (1-4) above were embedded using epoxy main agent (manufactured by Refinetech Co., Ltd., product name "Epomount Main Agent 27-771") and hardener (manufactured by Refinetech Co., Ltd., product name "Epomount Hardener 27-772") as casting resin and cured. Next, waterproof abrasive paper (manufactured by Refinetech Co., Ltd., φ200 mm, #2000) was placed on a polishing machine (manufactured by Refinetech Co., Ltd., product name "RPO-128K Refine Polisher HV") and the cross-section of the test specimen was polished to reveal the cross-section of the via opening. Then, the cross-section of the via opening was buff polished with alumina liquid A (manufactured by Refinetech Co., Ltd., product name "44-212S") and the moisture was removed by heating in a 100°C oven for 10 minutes. Subsequently, platinum was deposited onto the cross-section of the via opening, and the bottom of the via opening was observed in cross-section at a magnification of 10,000x using a scanning electron microscope (Hitachi High-Tech Corporation, SU5000) to evaluate the presence or absence of undercuts (presence or absence of gouging or missing parts at the bottom of the side wall forming the via opening). The results are shown in Tables 1 to 4.

[0111] Furthermore, for the test specimens in which the presence or absence of undercuts was evaluated, the taper angle of the side wall forming the via opening was measured by cross-sectional observation at a magnification of 5000x using a scanning electron microscope (SU5000, manufactured by Hitachi High-Tech Corporation). Here, "taper angle" refers to the angle θ between the permanent resist 60 and the printed circuit board substrate 50 when observing the cross-section of the via opening 70 formed in the permanent resist 60 on the printed circuit board substrate 50, as shown in Figure 2. The closer the taper angle θ is to 90° and does not exceed 95°, the better the shape of the via opening is considered to be. The shape of the via opening was evaluated from the measured taper angle θ according to the following criteria. If the evaluation result was A or B, it was determined that a via opening with a good shape had been formed. The results are shown in Tables 1 to 4. A: Taper angle is 80° or more and 90° or less. B: Taper angle is 70° or more and less than 80°, or greater than 90° and less than or equal to 95°. C: Taper angle is 60° or more and less than 70°. D: Taper angle is less than 60° or greater than 95°.

[0112] (1-6) Measurement of the refractive index of the cured product While peeling off the protective film from the photosensitive elements obtained in the examples and comparative examples, the exposed photosensitive layer was laminated onto a silicon wafer using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500") for a vacuum time of 25 seconds, atmospheric pressure of 4 kPa or less, press hot plate temperature of 80°C, pressing pressure of 0.4 MPa, and lamination press time of 25 seconds. Next, from the support film side of the photosensitive layer, a parallel light exposure machine (manufactured by Oak Seisakusho Co., Ltd., product name "EXM-1201") using an ultra-high pressure mercury lamp as the light source was used to expose it at 200 mJ / cm². ２ The entire surface was exposed, and the support film was peeled off after exposure. A matching solution was applied to the surface of the cured photosensitive layer on the silicon wafer, and the refractive index of the cured photosensitive layer on the silicon wafer was measured under the following conditions while in close contact with a prism. The results are shown in Tables 1 to 4. • Measurement device: Model 2010 / M PRISM COUPLER, manufactured by Metricon Corporation • Wavelength: 632.8 nm • Measurement temperature: 25°C • Measurement atmosphere: Air • Matching solution: IMMERSION LIQUID (nD=1.640), manufactured by Cargile Laboratories Inc.

[0113]

[0114]

[0115]

[0116]

[0117] 1...Photosensitive element, 10...Support film, 20...Photosensitive layer, 30...Protective film, 50...Substrate for printed circuit board, 60...Permanent resist, 70...Via opening.

Claims

1. A photosensitive element for permanent resist, comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer contains (A) an acid-modified vinyl group-containing resin, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) an inorganic filler, wherein the (D) inorganic filler includes an inorganic filler having a refractive index of 1.500 to 1.700, the thickness of the photosensitive layer is 5 to 35 μm, and the absorbance of the photosensitive layer for light at a wavelength of 380 nm is 0.40 to 1.

00.

2. The photosensitive element according to claim 1, wherein the content of the (D) inorganic filler in the photosensitive layer is 40 to 85% by mass based on the total amount of the photosensitive layer.

3. The photosensitive element according to claim 1, wherein the volume-average particle size of the inorganic filler (D) is 0.1 to 1.5 μm.

4. The photosensitive element according to claim 1, wherein the (D) inorganic filler includes composite particles of silica and a metal oxide other than silica.

5. The photosensitive element according to claim 4, wherein the composite particles include silica-titania composite particles.

6. The photosensitive element according to claim 1, wherein the photosensitive layer further contains (E) an ultraviolet absorber.

7. The photosensitive element according to claim 6, wherein the content of the (E) ultraviolet absorber in the photosensitive layer is 0.05 to 3.0% by mass based on the total amount of the photosensitive layer.

8. The photosensitive element according to claim 1, wherein the photosensitive layer further contains (F) a thermosetting resin.

9. A printed circuit board comprising a permanent resist including a cured photosensitive layer in a photosensitive element according to any one of claims 1 to 8.

10. A method for manufacturing a printed circuit board, comprising the steps of: forming a photosensitive layer on a substrate using a photosensitive element described in any one of claims 1 to 8; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form a permanent resist.

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