JP6782417B2 - Photosensitive resin composition, photosensitive element, resist pattern forming method and printed wiring board manufacturing method - Google Patents

Description

The present disclosure relates to a photosensitive resin composition, a photosensitive element, a method for forming a resist pattern, and a method for manufacturing a printed wiring board.

In the field of manufacturing printed wiring boards, a photosensitive resin composition or a layer formed by using a photosensitive resin composition as a resist material used for etching treatment, plating treatment, etc. (hereinafter referred to as "photosensitive layer"). ) Is widely used on the support.

Conventionally, a printed wiring board has been manufactured by, for example, the following procedure using the above-mentioned photosensitive element. That is, first, the photosensitive layer of the photosensitive element is laminated on a circuit-forming substrate such as a copper-clad laminate. Next, the photosensitive layer is exposed through a mask film or the like to form a photocurable portion. At this time, the support is peeled off at any timing before or after the exposure. Then, the region of the photosensitive layer other than the photocurable portion is removed with a developing solution. Next, an etching treatment or a plating treatment is performed to form a conductor pattern, and finally the photocured portion is removed.

In recent years, as the density of printed wiring boards has increased and the conductor pattern has become finer, the contact area between the circuit board and the photosensitive layer, which is a resist, has become smaller. Therefore, the photosensitive layer is required to have excellent characteristics in etching treatment or plating treatment, excellent adhesion to a circuit-forming substrate, and excellent resolution (resolution) in forming a resist pattern. Has been done. Above all, a material capable of forming a resist pattern having both a line width and a space width of 10 μm or less is required for a package substrate application, and in particular, recently, a resist pattern having both a line width and a space width of 5 μm or less is formed. Materials are desired, and demands for improvement in adhesion and resolution are becoming stricter year by year.

In relation to the above, various photosensitive resin compositions have been studied in order to form a resist pattern having excellent adhesion and resolution (see, for example, Patent Document 1 or 2). Patent Document 1 or 2 proposes to use a specific sensitizing dye or a specific binder polymer.

Japanese Unexamined Patent Publication No. 11-212263 Special Publication No. 58-323669

However, even the photosensitive resin composition described in the above prior art document is not sufficient for forming a fine resist pattern having both a line width and a space width of 10 μm or less, and there is room for improvement. ..

Further, as described above, the photosensitive resin composition is required to be further improved particularly in terms of resolution and adhesion. In addition, there is a continuous demand for improvement such as improvement in resolution and adhesion in units of 1 μm. Therefore, it is an object of the present disclosure to provide a photosensitive resin composition having excellent resolution and adhesion. It is also an object of the present disclosure to provide a method for manufacturing a photosensitive element and a resist pattern using the same, and a method for manufacturing a printed wiring board.

As a result of diligent studies to solve the above problems, the present inventors have found that the resolution and adhesion can be improved by adjusting the refractive index of the photosensitive resin composition. In particular, in a photosensitive resin composition containing (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, the photosensitive layer is controlled by controlling the refractive index of the (A) binder polymer. It was found that the refractive index of the polymer is easy to adjust, and that the above-mentioned characteristics (resolution and adhesion) are greatly affected.

That is, one aspect of the present disclosure contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, and the (A) binder polymer is derived from (meth) acrylic acid. The present invention relates to a photosensitive resin composition having the structural unit of (A) and having a refractive index of the binder polymer (A) of 1.504 or more. Further, the binder polymer (A) may further contain 65% by mass or more of structural units derived from at least one of styrene and a styrene derivative.

According to the photosensitive resin composition of the present disclosure, by containing (A) a binder polymer having a structural unit derived from (meth) acrylic acid and having a refractive index of 1.504 or more, resolution and adhesion are achieved. The sex can be improved. In particular, when a photosensitive layer is formed on a support using the photosensitive resin composition in a photosensitive element, the difference in refractive index between the photosensitive layer and the support can be reduced. Therefore, when the photosensitive layer is exposed through the support, light scattering (including light diffraction and refraction) at the interface between the support and the photosensitive layer can be suppressed, and resolution and adhesion can be improved. Can be done. Further, when the (A) binder polymer contains 65% by mass or more of structural units derived from at least one of styrene and the styrene derivative, the refractive index of the (A) binder polymer can be appropriately increased, and the resolution and resolution can be improved. Adhesion can be further improved. The photosensitive resin composition of the present disclosure can be used even when the photosensitive layer is exposed without passing through a support, and sufficient resolution and adhesion can be obtained.

In addition, as a result of diligent studies to solve the above problems, the present inventors have obtained the resolution and resolution by using the binder polymer (A) containing a predetermined amount of a specific structural unit in the photosensitive resin composition. It was found that the adhesion can be improved.

That is, another aspect of the present disclosure contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, wherein the (A) binder polymer is a styrene and a styrene derivative. The present invention relates to a photosensitive resin composition containing 65% by mass or more of structural units derived from at least one of the above.

According to the photosensitive resin composition of the present disclosure, the resolution and adhesion are improved by containing (A) a binder polymer containing 65% by mass or more of structural units derived from at least one of styrene and a styrene derivative. be able to. In particular, since the binder polymer (A) having the above configuration can appropriately increase the refractive index, when a photosensitive layer is formed on the support using the photosensitive resin composition in the photosensitive element, the photosensitive layer is formed. The difference in refractive index between the and the support can be reduced. Therefore, when the photosensitive layer is exposed through the support, light scattering (including light diffraction and refraction) at the interface between the support and the photosensitive layer can be suppressed, and resolution and adhesion can be improved. Can be done. The photosensitive resin composition of the present disclosure contains (A) a binder polymer containing 65% by mass or more of structural units derived from at least one of styrene and a styrene derivative, so that the photosensitive layer is formed without passing through a support. Even in the case of exposure, the resolution and adhesion can be improved.

The content of the structural unit derived from at least one of the styrene and the styrene derivative in the binder polymer (A) may be 85% by mass or less.

The refractive index of the photopolymerizable compound (B) may be 1.504 or more. Further, the photopolymerizable compound (B) may contain at least one kind of bisphenol A type (meth) acrylate having a refractive index of 1.504 or more.

The weight average molecular weight of the binder polymer (A) may be 1000 to 80,000. Further, the binder polymer (A) may further have a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 30 carbon atoms.

Moreover, the said (C) photopolymerization initiator may contain a hexaarylbiimidazole derivative or an acridine compound having one or more acridinyl groups.

Further, one aspect of the present disclosure relates to a photosensitive element including a support and a photosensitive layer formed on the support by using the photosensitive resin composition. Further, the haze of the support is 0.01 to 1.0%, the refractive index of the support is 1.504 or more, and the support is formed by using polyethylene terephthalate. You may.

By using the above-mentioned photosensitive element, it is possible to sufficiently reduce the difference in refractive index between the support and the photo tool used as a mask or the photosensitive layer, particularly when forming a fine resist pattern. , It is considered that the resolution and adhesion can be improved.

Further, one aspect of the present disclosure is (i) a step of forming a photosensitive layer on a substrate by using the photosensitive resin composition or the photosensitive element, and (ii) a predetermined portion of the photosensitive layer. A method for forming a resist pattern, comprising a step of irradiating the substrate with an active light beam to form a photocurable portion, and (iii) a step of removing at least a part of the photosensitive layer other than the photocurable portion from the substrate. Regarding.

Further, one aspect of the present disclosure relates to a method for manufacturing a printed wiring board, comprising a step of forming a conductor pattern by etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern. Further, the method for manufacturing the printed wiring board may further include a step of removing the photocurable portion after the etching treatment or the plating treatment.

According to the present disclosure, it is possible to provide a photosensitive resin composition having excellent resolution and adhesion.

It is a schematic cross-sectional view which shows one Embodiment of the photosensitive element of this disclosure.

Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the drawings in some cases. However, the present disclosure is not limited to the following embodiments. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. Moreover, the dimensional ratio of the drawing is not limited to the ratio shown in the drawing.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the desired action of the process is achieved even if it cannot be clearly distinguished from other processes. Is done. In addition, the numerical range indicated by using "~" indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. Further, in the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step may be replaced with the upper limit value or the lower limit value of the numerical range of another step. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. Further, the term "layer" includes a structure having a shape formed on the entire surface and a structure having a shape formed on a part of the structure when observed as a plan view. Further, "(meth) acrylic acid" means at least one of "acrylic acid" and the corresponding "methacrylic acid". The same applies to other similar expressions such as (meth) acrylate.

Further, when the amount of each component in the composition is referred to in the present specification, when a plurality of substances corresponding to each component are present in the composition, the plurality of substances present in the composition unless otherwise specified. Means the total amount of substances in.

<Photosensitive resin composition>
The photosensitive resin composition of the present embodiment contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator. In addition, in this specification, these components may be simply referred to as a component (A), a component (B), a component (C), and the like. In addition, a sensitizer, a hydrogen donor or other components may be contained, if necessary. Hereinafter, each component used in the photosensitive resin composition of the present embodiment will be described in more detail.

((A) Binder polymer)
The component (A) has a structural unit derived from (meth) acrylic acid from the viewpoint of improving resolution and adhesion, and may have a refractive index of 1.504 or more. Further, from the viewpoint of easy availability and easy economic benefit, the component (A) is a structural unit derived from at least one of styrene and a styrene derivative (also referred to as “styrene-based structural unit”). ) May be contained in an amount of 65% by mass or more based on the total solid content of the component. Further, when the component (A) contains a styrene-based structural unit in the above range, the resolution and adhesion tend to be improved.

The "refractive index" described in this embodiment is a theoretical value calculated by mass ratio from the refractive index of each structural unit of the binder polymer. The refractive index can be adjusted by changing the type and content (mass ratio) of the structural unit. Examples of refractive indexes of structural units of various binder polymers are shown in Table 1 below (J. Brandrup, E. H. Immunogut, and EA Grulke, "Polymer Handbook Fourth Edition", Wiley, 2003. May, III / 8-17 and III / 34-35). The refractive index in this embodiment can also be said to be an absolute refractive index. In the calculation of the refractive index, the refractive index when the monomer (structural unit) from which the component (A) is derived is measured independently is used. The refractive index of the component (B) described later is the refractive index when the photopolymerizable compound is measured alone. When the component (B) contains a plurality of photopolymerizable compounds, the refractive index obtained by measuring each of the photopolymerizable compounds independently is used for calculating the refractive index of the entire component (B).

The refractive index of the component (A) of the present embodiment may be 1.504 or more, 1.510 or more, or 1.514 or more from the viewpoint of improving the resolvability. When the refractive index of the component (A) is 1.504 or more, the photosensitive resin composition is exposed even when a fine pattern having an L / S (line width / space width) of 5 μm or less is exposed. It is possible to suppress the influence of diffraction and refraction of light that penetrates into the photosensitive layer formed by using the above, and the resolution and adhesion are sufficiently excellent. In particular, when used as a photosensitive element, the difference in refractive index (absolute value) between the support and the photosensitive layer is reduced to 0.100 or less to prevent light scattering at the interface between the support and the photosensitive layer. It can be suppressed, and its resolution and adhesion are particularly excellent. That is, one aspect of the present disclosure can be said to be a photosensitive element in which the difference in refractive index between the support and the photosensitive layer is 0.100 or less. Further, it can be said that it is a photosensitive element in which the difference in refractive index between the support and the component (A) in the photosensitive layer is 0.100 or less. From the viewpoint of improving the resolution, the refractive index of the component (A) may be 1.600 or less, 1.540 or less, or 1.530 or less.

The component (A) may have a styrene-based structural unit from the viewpoint of improving the solubility of the photosensitive layer in the developing solution and the resistance of the developing solution after exposure in a well-balanced manner. Further, the component (A) has a styrene-based structural unit of 65% by mass or more and 68% by mass based on the total solid content of the component (A) from the viewpoint of improving resolution and adhesion. Or more, or 70% by mass or more may be contained. On the other hand, the content of the styrene-based structural unit may be 85% by mass or less, 82% by mass or less, or 80% by mass or less. When the content of the styrene-based structural unit is not more than the above upper limit value, the development time is appropriately shortened, and it is easy to obtain advantages such as less development residue. When the refractive index of the component (A) is 1.504 or more, the content of the styrene-based structural unit in the component (A) may be 50% by mass or more.

The styrene-based structural unit may contain a structural unit derived from styrene, and the content thereof is based on the total amount of the styrene-based structural unit from the viewpoint of improving resolution and adhesion. , 30% by mass or more, 50% by mass or more, 80% by mass or more, or 90% by mass or more. The upper limit may be 100% by mass.

The styrene derivative is a polymerizable compound in which a hydrogen atom in the α-position or aromatic ring of styrene is substituted with a substituent, such as vinyltoluene and α-methylstyrene. The styrene derivative may be a compound represented by the following general formula (I) from the viewpoint of improving the hydrophobicity of the binder polymer.

In the above general formula (III), R ¹¹ independently represents a hydrogen atom or a methyl group, and R ¹² independently represents a hydrogen atom, an alkyl group, an acryloyl group, a phenyl group or a derivative thereof.

When a support film formed by using polyethylene terephthalate (PET) is used among the supports, it has a structural unit derived from (meth) acrylic acid and has a styrene-based structural unit of 65% by mass or more (A). By using the components, the difference in refractive index can be made smaller. When the component (A) contains 85% by mass of a styrene-based structural unit, its refractive index is about 1.53.

As the support, a support film formed by using PET (sometimes simply referred to as "PET film") may be used from the viewpoint of being easily available and improving the handleability in the manufacturing process. Good. The refractive index of the PET film is about 1.57 to 1.60. Further, the haze of the PET film may be 0.01 to 1.0% for the purpose of reducing the minute defects that may occur in the resist pattern.

The weight average molecular weight (Mw) of the component (A) may be 1000 to 80000, 15000 to 70000, or 20000 to 50000. The dispersity (Mw / Mn) may be 1.0 to 3.0 or 1.0 to 2.3. When Mw is 80,000 or less, the resolvability and developability tend to be improved. Further, as the degree of dispersion becomes smaller, the resolution tends to improve. On the other hand, when Mw is 10,000 or more, the flexibility of the cured film is improved, and the resist pattern tends to be less likely to be chipped or peeled off. Further, when Mw is 10,000 or more, the coating film property tends to be improved. The weight average molecular weight of the binder polymer is measured by gel permeation chromatography (GPC) (converted by a calibration curve using standard polystyrene).

Structural units derived from other than (meth) acrylic acid, styrene or styrene derivatives include, for example, (meth) acrylic acid alkyl ester, (meth) acrylic acid benzyl ester or its derivative, (meth) acrylic acid cycloalkyl ester, ( (Meta) Acrylic acid flufuryl ester, (Meta) Acrylic acid tetrahydrofurfuryl ester, (Meta) Acrylic acid Isobornyl ester, (Meta) Acrylic acid adamantyl ester, (Meta) Acrylic acid dicyclopentanyl ester, (Meta) Acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, (meth) acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl ( Meta) acrylate, β-frill (meth) acrylic acid, β-styryl (meth) acrylic acid, maleic acid, maleic acid anhydride, maleic acid monoalkyl ester, fumaric acid, silicic acid, α-cyanosilicic acid, itacon Acrylic, crotonic acid, propioleic acid can be mentioned. These can be used individually by 1 type or in combination of 2 or more types.

Among them, the component (A) may further have a structural unit derived from a (meth) acrylic acid alkyl ester, a structural unit derived from a (meth) benzyl acrylate or a (meth) benzyl acrylate derivative, and the like. In particular, the component (A) may have a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 30 carbon atoms. Thereby, the flexibility and the peelability can be improved in a well-balanced manner. From the viewpoint of further improving the flexibility and peelability, the number of carbon atoms may be 1 to 10 or 2 to 6. From the viewpoint of further improving the peeling characteristics, the alkyl group may have 1 to 4 carbon atoms.

The content of the structural unit derived from (meth) acrylic acid is as follows: the acid value of the component (A) is 100 to 250 mgKOH / g, the content is 120 to 240 mgKOH / g, and the content is 140 to 230 mgKOH / g. The content may be 150 to 230 mgKOH / g. When the acid value of the component (A) is 100 mgKOH / g or more, it is possible to sufficiently suppress a long development time. Further, when it is 250 mgKOH / g or less, the developer resistance (adhesion) of the cured product of the photosensitive resin composition is improved.

The acid value of the component (A) can be measured as follows. That is, first, 1 g of the binder polymer whose acid value is to be measured is precisely weighed. 30 g of acetone is added to the finely weighed binder polymer, and this is uniformly dissolved. Next, an appropriate amount of phenolphthalein, which is an indicator, is added to the solution, and titration is performed using a 0.1 N potassium hydroxide (KOH) aqueous solution. The acid value is determined by calculating the number of mg of KOH required to neutralize the acetone solution of the binder polymer to be measured. When a solution obtained by mixing a binder polymer with a synthetic solvent, a diluting solvent, etc. is used as a measurement target, the acid value is calculated by the following formula.
Acid value = 0.1 x Vf x 56.1 / (Wp x I / 100)
In the formula, Vf indicates the titer (mL) of the KOH aqueous solution, Wp indicates the mass (g) of the measured solution containing the binder polymer, and I indicates the ratio of the non-volatile content in the measured solution containing the binder polymer. (Mass%) is shown. When the binder polymer is mixed with volatile components such as a synthetic solvent and a diluting solvent, it is volatile by heating it in advance at a temperature 10 ° C. or higher higher than the boiling point of the volatile components for 1 to 4 hours before weighing. It is also possible to measure the acid value after removing the minutes.

The content of the structural unit derived from (meth) acrylic acid may be 10 to 35% by mass from the viewpoint of improving the resolution and adhesion based on the total solid content of the component (A). , 15% by mass or more, 20% by mass or more, or 22% by mass or more.

When the component (A) contains a structural unit derived from the (meth) acrylic acid alkyl ester, the content thereof is 1 to 30% by mass and 2 to 15% by mass based on the total solid content of the component (A). %, Or 3 to 10% by mass. When this content is 1% by mass or more, it is possible to suppress the peeling piece from becoming large and the peeling time from becoming long. When it is 30% by mass or less, the resolution is improved.

In the photosensitive resin composition of the present embodiment, as the component (A), one kind of binder polymer may be used alone, or two or more kinds of binder polymers may be used in any combination. When two or more kinds of binder polymers are used in combination, for example, two or more kinds of binder polymers (including different monomer units as copolymerization components) composed of different copolymerization components, and two or more kinds of different weight average molecular weights. Binder polymers and two or more types of binder polymers with different dispersities can be mentioned. Further, a polymer having a multimode molecular weight distribution described in JP-A-11-327137 can also be used.

The content of the component (A) in the photosensitive resin composition of the present embodiment is 20 to 90% by mass, 30 to 80% by mass, or 40 to 65% by mass based on the total solid content of the photosensitive resin composition. May be%. When this content is 20% by mass or more, the formability of the film tends to be excellent. Further, when it is 90% by mass or less, the sensitivity and the resolution tend to be excellent.

((B) Photopolymerizable compound)
The component (B) used in the present embodiment is not particularly limited as long as it has at least one ethylenically unsaturated bond and is a photopolymerizable compound. From the viewpoint of improving the resolution and adhesion, the refractive index of the component (B) may be 1.504 or more, 1.510 or more, or 1.515 or more. The refractive index of the component (B) is a value calculated based on the refractive index and the content rate of each photopolymerizable compound when a plurality of photopolymerizable compounds are contained.

The difference (absolute value) in the refractive index between the component (A) and the component (B) is 0.030 or less, 0.025 or less, 0.020 or less, or 0.020 or less from the viewpoint of further improving the resolution and adhesion. , 0.010 or less.

The component (B) may contain at least one of bisphenol A type (meth) acrylate from the viewpoint of improving alkali developability, resolution and peeling characteristics after curing, and has a refractive index of 1.504 or more. It may contain at least one kind of bisphenol A type (meth) acrylate which is.

Examples of the bisphenol A type (meth) acrylate include 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane and 2,2-bis (4-((meth) acryloxypolypropoxy) phenyl). ) Propane, 2,2-bis (4-((meth) acryloxipolybutoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxipolyethoxypolypropoxy) phenyl) propane and the like. .. Of these, 2,2-bis (4-((meth) acryloxipolyethoxy) phenyl) propane is preferable from the viewpoint of further improving the resolution and peeling characteristics.

Of these, commercially available ones include, for example, 2,2-bis (4-((meth) acryloxidipropoxy) phenyl) propane, BPE-200 (Shin Nakamura Chemical Industry Co., Ltd.). , 2,2-Bis (4- (methacryloxypentaethoxy) phenyl) propane includes BPE-500 (Shin Nakamura Chemical Industry Co., Ltd.) or FA-321M (Hitachi Chemical Co., Ltd.). The refractive index is 1.512 for BPE-200 and 1.532 for BPE-500. These bisphenol A type (meth) acrylates are used alone or in any combination of two or more.

The content of the bisphenol A type (meth) acrylate may be 30 to 100% by mass or 50% by mass to 90% by mass in the total mass of the component (B). The resolution is further improved when the content is in such a range.

As the component (B) other than the bisphenol A type (meth) acrylate, at least of the (poly) oxyethylene chain and the (poly) oxypropylene chain in the molecule from the viewpoint of improving the flexibility of the cured product (cured film). It may further contain at least one of the polyalkylene glycol di (meth) acrylate having one, and the polyalkylene glycol di (meth) having both a (poly) oxyethylene chain and a (poly) oxypropylene chain in the molecule. It may further contain acrylate. Examples of the polyalkylene glycol di (meth) acrylate include FA-023M (Hitachi Chemical Co., Ltd.), FA-024M (Hitachi Chemical Co., Ltd.), NK Ester HEMA-9P (Shin Nakamura Chemical Industry Co., Ltd.), and the like. Can be mentioned. These can be used alone or in combination of two or more.

In addition, examples of the other component (B) include nonylphenoxypolyethylene oxyacrylate, a phthalic acid compound, a (meth) acrylic acid polyol ester, and a (meth) acrylic acid alkyl ester. Among them, at least one selected from nonylphenoxypolyethylene oxyacrylate and phthalic acid-based compounds may be contained from the viewpoint of improving the resolution, adhesion, resist shape and peeling characteristics after curing in a well-balanced manner. However, since the refractive index of these compounds is relatively low, the content thereof is 5 to 50% by mass or 10 to 30% by mass in the total mass of the component (B) from the viewpoint of improving the resolution. May be%.

Examples of the nonylphenoxypolyethyleneoxyacrylate include nonylphenoxytriethyleneoxyacrylate, nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, and nonylphenoxyoctaethylene. Examples thereof include oxyacrylate, nonylphenoxy nonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, and nonylphenoxyundecaethyleneoxyacrylate.

Examples of the phthalic acid compound include γ-chloro-β-hydroxypropyl-β'-(meth) acryloyloxyethyl-o-phthalate and β-hydroxyethyl-β'-(meth) acryloyloxyethyl-o. -Futalate and β-hydroxypropyl-β'-(meth) acryloyloxyethyl-o-phthalate are mentioned, and among them, γ-chloro-β-hydroxypropyl-β'-(meth) acryloyloxyethyl-o- It may be phthalate. γ-Chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate is commercially available as FA-MECH (Hitachi Chemical Co., Ltd.).

Further, the component (B) may contain a (meth) acrylic acid polyol from the viewpoint of improving the sensitivity and reducing the tailing. Examples of the (meth) acrylic acid polyol ester include trimethylolpropane polyethoxytri (meth) acrylate, trimethylolpropane polypropoxytri (meth) acrylate, trimethylolpropane polybutoxytri (meth) acrylate, and trimethylolpropane polyethoxy. Polypropoxytri (meth) acrylate, trimethylolethane polyethoxytri (meth) acrylate, trimethylolethane polypropoxytri (meth) acrylate, trimethylolethane polybutoxytri (meth) acrylate, trimethylolethane polyethoxypolypropoxytri ( Meta) acrylate, pentaerythritol polyethoxytri (meth) acrylate, pentaerythritol polypropoxytri (meth) acrylate, pentaerythritol polybutoxytri (meth) acrylate, pentaerythritol polyethoxypolypropoxytri (meth) acrylate, glyceryl polyethoxytri Examples thereof include (meth) acrylate, glyceryl polypropoxytri (meth) acrylate, glyceryl polybutoxytri (meth) acrylate, and glyceryl polyethoxypolypropoxytri (meth) acrylate.

The other photopolymerizable compounds may be used alone or in combination of two or more.

The content of the component (B) may be 3 to 70% by mass, 10 to 60% by mass, or 25 to 55% by mass based on the total solid content of the photosensitive resin composition. When this content is 3% by mass or more, the sensitivity and resolution tend to be excellent. Further, when it is 70% by mass or less, the formability of the film tends to be excellent.

The content of the component (B) is preferably 20 to 60% by mass, more preferably 30 to 55% by mass, based on the total amount of the components (A) and (B), and 35 to 50%. It is particularly preferable to use% by mass. When the content of the component (B) is in this range, in addition to the resolution and adhesion of the photosensitive resin composition, the light sensitivity and the coating film property become better.

((C) Photopolymerization Initiator)
The component (C) is not particularly limited, but may contain a hexaarylbiimidazole derivative or an acridine compound having one or more acridinyl groups in terms of improving sensitivity and resolution in a well-balanced manner. From the viewpoint of improving sensitivity and resolution at a high level, the component (C) may contain a hexaarylbiimidazole derivative. In particular, when the photosensitive layer is exposed with active light of 390 nm to 420 nm, an acridine compound having one or more acridinyl groups may be contained from the viewpoint of sensitivity and adhesion.

Examples of the hexaarylbiimidazole derivative include 2- (o-chlorophenyl) -4,5-diphenylbiimidazole, 2,2', 5-tris- (o-chlorophenyl) -4- (3,4-dimethoxyphenyl). ) -4', 5'-diphenylbiimidazole, 2,4-bis- (o-chlorophenyl) -5- (3,4-dimethoxyphenyl) -diphenylbiimidazole, 2,4,5-tris- (o-) Chlorophenyl) -diphenylbiimidazole, 2- (o-chlorophenyl) -bis-4,5- (3,4-dimethoxyphenyl) -biimidazole, 2,2'-bis- (2-fluorophenyl) -4,4 ', 5,5'-tetrakis- (3-methoxyphenyl) -biimidazole, 2,2'-bis- (2,3-difluoromethylphenyl) -4,4', 5,5'-tetrakis- (3 -Methoxyphenyl) -biimidazole, 2,2'-bis- (2,4-difluorophenyl) -4,4', 5,5'-tetrax- (3-methoxyphenyl) -biimidazole, 2,2' -Bis- (2,5-difluorophenyl) -4,4', 5,5'-tetrakis- (3-methoxyphenyl) -biimidazole and the like can be mentioned. Of these, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer is preferable from the viewpoint of sensitivity and resolution.

Examples of the acridine compound include 9-phenylacridine, 9- (p-methylphenyl) acridine, 9- (m-methylphenyl) acridine, 9- (p-chlorophenyl) acridine, 9- (m-chlorophenyl) acridine, and the like. 9-Aminoacridine, 9-dimethylaminoacridine, 9-diethylaminoacridine, 9-pentylaminoacridine, 1,2-bis (9-acridinyl) ethane, 1,4-bis (9-acridinyl) butane, 1,6- Bis (9-acridinyl) hexane, 1,8-bis (9-acridinyl) octane, 1,10-bis (9-acridinyl) decane, 1,12-bis (9-acridinyl) dodecane, 1,14-bis ( Bis (9-acridinyl) alkanes such as 9-acridinyl) tetradecane, 1,16-bis (9-acridinyl) hexadecane, 1,18-bis (9-acridinyl) octadecane, 1,20-bis (9-acridinyl) eikosan , 1,3-bis (9-acridinyl) -2-oxapropane, 1,3-bis (9-acridinyl) -2-thiapropane, 1,5-bis (9-acridinyl) -3-thiapentane and the like. .. These are used alone or in combination of two or more.

Other photopolymerization initiators include, for example, benzophenones such as 4,4'-bis (diethylamino) benzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-. Aromatic ketones such as methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1, quinones such as alkylanthraquinone, benzoin ether compounds such as benzoin alkyl ethers, benzoin compounds such as benzoin and alkylbenzoin , Benzyl derivatives such as benzyl dimethyl ketal, N-phenylglycine, N-phenylglycine derivatives, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Acylphosphine oxide-based photopolymerization initiators such as oxides, 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (O-benzoyloxime)], etanone, 1- [9-ethyl- Examples thereof include oxime ester compounds such as 6- (2-methylbenzoyl) -9H-carbazole-3-yl]-, 1- (O-acetyloxime). These may be used in combination with a hexaarylbiimidazole derivative or an acridine compound.

The content of the component (C) may be 0.1 to 10% by mass, 1 to 5% by mass, or 2% by mass to 4.5% by mass based on the total solid content of the photosensitive resin composition. Good. With this content, it tends to be easy to improve both the light sensitivity and the resolution in a well-balanced manner.

The content of the component (C) is 0.1 to 10 parts by mass, 1 to 5 parts by mass, or 2 to 4.5 with respect to 100 parts by mass of the total amount of the components (A) and (B). It may be a mass part. With this content, it tends to be easy to improve both the light sensitivity and the resolution in a well-balanced manner.

The total content of the components (A), (B), and (C) is based on the total solid content of the photosensitive resin composition from the viewpoint of improving the light sensitivity and the resolution in a well-balanced manner. , 85% by mass or more, 90% by mass or more, or 93% by mass or more. The upper limit is not particularly limited, but may be 100% by mass or less, or 99% by mass or less.

(Sensitizer)
The photosensitive resin composition of the present embodiment may further contain a sensitizer. As a result, the light sensitivity of the photosensitive resin composition becomes even better. Examples of the sensitizer include dialkylaminobenzophenones, pyrazolines, anthracenes, coumarins, xanthones, oxazoles, benzoxazoles, thiazoles, benzothiazoles, triazoles, stillbens, triazines and thiophenes. , Naphthalimides, triarylamines and the like. These are used alone or in combination of two or more. In particular, when the photosensitive layer is exposed with active light of 390 nm to 420 nm, at least one selected from the group consisting of pyrazolines, anthracenes, coumarins and triarylamines is selected from the viewpoint of sensitivity and adhesion. Species may be included, and at least one selected from the group consisting of pyrazolines, anthracenes and triarylamines may be included.

When a sensitizer is contained, the content thereof is 0.01 to 10% by mass, 0.05 to 5% by mass, or 0.1 based on the total solid content of the components (A) and (B). It may be ~ 3% by mass. When this content is 0.01% by mass or more, the sensitivity and resolution are further improved. Further, when it is 10% by mass or less, it is possible to prevent the resist shape from becoming an inverted trapezoid and improve the adhesion.

(Hydrogen donor)
The photosensitive resin composition of the present embodiment may further contain a hydrogen donor. As a result, the sensitivity of the photosensitive resin composition becomes even better. Examples of the hydrogen donor include bis [4- (dimethylamino) phenyl] methane, bis [4- (diethylamino) phenyl] methane, N-phenylglycine, and leucocrystal violet. These are used alone or in combination of two or more.

When a hydrogen donor is contained, the content thereof is 0.01 to 10% by mass, 0.05 to 5% by mass, or 0.1 based on the total solid content of the components (A) and (B). It may be ~ 2% by mass. When this content is 0.01% by mass or more, the sensitivity is further improved. Further, when it is 10% by mass or less, it is possible to suppress the precipitation of excess hydrogen donor as a foreign substance after the film is formed.

(Other ingredients)
The photosensitive resin composition of the present embodiment may contain other components, if necessary. Other components include, for example, a photopolymerizable compound (oxetane compound, etc.) having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, a dye such as malachite green, tribromophenyl sulfone, and light. Adhesion of color formers, thermal color inhibitors, plasticizers such as p-toluenesulfonamide, polymerization inhibitors such as tert-butylcatechol, pigments, fillers, antifoaming agents, flame retardants, stabilizers, benzotriazole, etc. Examples thereof include agents, leveling agents, peeling accelerators, antioxidants, fragrances, imaging agents, and thermal cross-linking agents. These are used alone or in combination of two or more. Further, the content of these other components may be about 0.01 to 20% by mass, respectively, based on the total solid content of the photosensitive resin composition.

The photosensitive resin composition of the present embodiment may contain at least one organic solvent in order to improve the handleability of the photosensitive composition and to adjust the viscosity and storage stability. As the organic solvent, a commonly used organic solvent can be used without particular limitation. Specific examples thereof include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, propylene glycol monomethyl ether, and a mixed solvent thereof. For example, the component (A), the component (B), and the component (C) are dissolved in the organic solvent and used as a solution having a solid content of about 30 to 60% by mass (hereinafter referred to as "coating liquid"). be able to. The "solid content" refers to the non-volatile content of the photosensitive resin composition excluding volatile substances such as water and solvent. That is, it refers to components other than the solvent that remain without volatilizing in the drying step, and includes liquid, starch syrup-like, and wax-like components at room temperature around 25 ° C.

<Photosensitive element>
The photosensitive element of the present embodiment includes a support and a photosensitive layer formed on the support using the photosensitive resin composition. When the photosensitive element of the present embodiment is used, the photosensitive layer may be laminated on the substrate and then exposed without peeling the support (support film). The photosensitive element 1 according to the present embodiment has a support 2 and a photosensitive layer 3 derived from the photosensitive resin composition formed on the support 2, as shown in FIG. 1 for a schematic cross-sectional view of an example thereof. And other layers such as a protective layer 4 provided as needed.

(Support)
As the support, a polymer film (support film) having heat resistance and solvent resistance such as polyester such as polyethylene terephthalate (PET) and polyolefin such as polypropylene and polyethylene can be used. Among them, a PET film may be used because it is easily available and is excellent in handleability (particularly, heat resistance, heat shrinkage rate, breaking strength) in the manufacturing process.

The refractive index of the support may be 1.504 or more, 1.530 or more, or 1.570 or more, or 1.700 or less, 1.660 or less, or 1.600 or less. .. When the refractive index of the support is within the above range, the difference in the refractive index from the photosensitive layer can be appropriately reduced, and when the photosensitive layer is exposed through the support, the interface between the support and the photosensitive layer is exposed. Scattering of light can be suppressed, and resolution and adhesion can be improved. The refractive index of the support can be measured by a known method.

The haze of the support may be 0.01-1.0% or 0.01-0.5%. When the haze is 0.01% or more, the support itself tends to be easy to manufacture, and when it is 1.0% or less, there is a tendency to reduce the minute defects that may occur in the resist pattern. Here, "haze" means the degree of cloudiness. The haze in the present disclosure refers to a value measured using a commercially available turbidity meter (turbidity meter) in accordance with the method specified in JIS K 7105. The haze can be measured with a commercially available turbidity meter such as NDH-5000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.).

Further, the number of particles or the like contained in the support having a diameter of 5 μm or more is 5 particles / mm ² or less, and the support may contain particles. As a result, the slipperiness of the surface of the support can be improved, and the suppression of light scattering during exposure, the resolution and the adhesion can be improved in a well-balanced manner. The average particle size of the particles is 5 μm or less, may be 1 μm or less, and may be 0.1 μm or less in particular. The lower limit is not particularly limited, but may be 0.001 μm or more. Particles with a diameter of 5 μm or more have a diameter of 5 μm or more when observed using a polarizing microscope (however, if the observed particle shape is not circular, it means the diameter of the circumscribed circle of that shape). It is a particle or the like having, and means a particle or the like existing on the surface of the support. Further, the particles and the like are not particularly limited as long as they give irregularities to the layer in contact with the support, but for example, a lubricant contained to add slipperiness to the surface of the support, or intentionally sprayed onto the support. During the production of organic particles or inorganic particles (hereinafter, also referred to as "sprayed particles"), foreign substances, aggregates (for example, lubricant aggregates, spray particle aggregates, or polymer gels, raw materials monomers, supports The catalyst used, the agglomerates formed by agglomerating inorganic or organic fine particles contained in the film as needed), and the lubricant generated when the lubricant layer (layer containing the lubricant) is applied onto the support. Includes swelling due to adhesives and the like. The shape of the particles and the like is not particularly limited, but may be a regular shape such as a spherical shape or an irregular shape. The material of the particles and the like is not particularly limited, but may be an organic substance or an inorganic substance such as a metal. In order to reduce the number of particles having a diameter of 5 μm or more to 20 particles / mm ² or less, those particles having a small particle size or those having excellent dispersibility may be selectively used.

Commercially available such supports include, for example, "QS-48" (Toray Industries, Inc.), "QS-48" (Toray Industries, Inc.), which is a biaxially oriented PET film having a three-layer structure containing particles in the outermost layer. FB-40 "(Toray Industries, Inc.)," HTF-01 "(Teijin DuPont Film Co., Ltd.), Biaxially oriented PET film" A-1517 "with a two-layer structure having a layer containing particles on one side. (Toyobo Co., Ltd.) and the like. The refractive index of these PET films is 1.57 to 1.60. The refractive index of the support can be measured by a known method.

The thickness of the support may be 1 to 100 μm or 5 to 50 μm. When the thickness is 1 μm or more, it is possible to prevent the support from being torn when the support is peeled off. Further, when it is 100 μm or less, it is possible to suppress a decrease in resolution when exposure is performed through a support. Further, from the viewpoint of further improving the resolution, the upper limit of the thickness of the support may be 30 μm or 20 μm.

(Protective layer)
The photosensitive element may be further provided with a protective layer, if necessary. As the protective layer, a film may be used in which the adhesive force between the photosensitive layer and the protective layer is smaller than the adhesive force between the photosensitive layer and the support, and a low fish eye film may be used. You may use it. Specifically, for example, those that can be used as the above-mentioned support can be mentioned. From the viewpoint of peelability from the photosensitive layer, a polyethylene film may be used. The thickness of the protective layer varies depending on the application, but may be about 1 to 100 μm.

<Manufacturing method of photosensitive element>
The photosensitive element can be manufactured, for example, as follows. That is, a coating liquid (that is, a photosensitive resin composition containing an organic solvent) is applied onto the support to form a coating layer, which is dried to form a photosensitive layer. Next, by covering the surface of the photosensitive layer opposite to the support with a protective layer, the support, the photosensitive layer formed on the support, and the protective layer laminated on the photosensitive layer are formed. The photosensitive element of the present embodiment is obtained.

The coating liquid can be applied onto the support by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, and bar coating.

Further, the drying of the coating layer is not particularly limited as long as at least a part of the organic solvent can be removed from the coating layer. For example, it may be carried out at 70 to 150 ° C. for about 5 to 30 minutes. After drying, the amount of residual organic solvent in the photosensitive layer may be 2% by mass or less from the viewpoint of preventing diffusion of the organic solvent in a later step.

The thickness of the photosensitive layer in the photosensitive element can be appropriately selected depending on the intended use, but the thickness after drying may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm. When the thickness is 1 μm or more, industrial coating is facilitated and productivity is improved. Further, when it is 100 μm or less, the adhesion and the resolvability are improved.

The transmittance of the photosensitive layer with respect to ultraviolet rays may be 5 to 75%, 10 to 65%, or 15 to 55% with respect to ultraviolet rays having a wavelength of 365 nm. When the transmittance is 5% or more, the adhesion is further improved. Further, when the transmittance is 75% or less, the resolution is further improved. The transmittance can be measured by a UV spectrometer. Examples of the UV spectrometer include a 228A type W beam spectrophotometer (Hitachi, Ltd.).

The refractive index of the photosensitive layer may be 1.504 or more, 1.510 or more, or 1.514 or more, and may be 1.600 or less, 1.540 or less, or 1.530 or less. .. When the refractive index of the photosensitive layer is within the above range, the difference in the refractive index from the support can be appropriately reduced, and when the photosensitive layer is exposed through the support, the interface between the support and the photosensitive layer is exposed. Scattering of light can be suppressed, and resolution and adhesion can be improved. The refractive index of the photosensitive layer can be measured by a known method.

The photosensitive element can be suitably used, for example, in a resist pattern forming method described later. Above all, from the viewpoint of resolution, it is suitable for application to a manufacturing method for forming a conductor pattern by plating.

<Method of forming resist pattern>
The method for forming the resist pattern of the present embodiment includes (i) a step of forming a photosensitive layer on a substrate by using the photosensitive resin composition or the photosensitive element (photosensitive layer forming step), and ii) At least a part (predetermined part) of the photosensitive layer is irradiated with active light to form a photocurable portion (exposure step), and (iii) at least a part other than the photocurable portion from the substrate. A step (development step) for removing the above-mentioned light is provided, and other steps may be included if necessary. The resist pattern can be said to be a photocured product pattern of the photosensitive resin composition or a relief pattern. Further, the method of forming a resist pattern can be said to be a method of manufacturing a substrate with a resist pattern.

((I) Photosensitive layer forming step)
As a method of forming the photosensitive layer on the substrate, for example, the photosensitive resin composition may be applied and dried, or the photosensitive layer of the photosensitive element may be formed after removing the protective layer from the photosensitive element. It may be crimped to the above substrate while heating. When a photosensitive element is used, a laminate composed of a substrate, a photosensitive layer, and a support, and these are laminated in this order can be obtained. The substrate is not particularly limited, but usually, a circuit forming substrate having an insulating layer and a conductor layer formed on the insulating layer, or a die pad (lead frame substrate) such as an alloy substrate is used.

When a photosensitive element is used, the photosensitive layer forming step is preferably performed under reduced pressure from the viewpoint of adhesion and followability. The photosensitive layer and / or the substrate may be heated at a temperature of 70 to 130 ° C. during crimping. Further, the crimping may be performed at a pressure of about 0.1 to 1.0 MPa (about 1 to 10 kgf / cm ² ), but these conditions are appropriately selected as necessary. If the photosensitive layer is heated to 70 to 130 ° C., it is not necessary to preheat the substrate in advance, but the substrate can be preheated in order to further improve the adhesion and the followability.

((Ii) exposure step)
In the exposure step, by irradiating at least a part of the photosensitive layer formed on the substrate with active light, the portion irradiated with the active light is photocured to form a latent image. At this time, when the 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, but if the support is light-shielding. Irradiates the photosensitive layer with active light rays after removing the support.

Examples of the exposure method include a method of irradiating an active ray in an image shape through a negative or positive mask pattern called artwork (mask exposure method). Further, a method of irradiating an active ray in an image shape by a projection exposure method may be adopted. Further, a method of irradiating an active ray in an image shape by a direct drawing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be adopted.

As the light source of the active light, a known light source can be used, for example, a carbon arc lamp, a mercury steam arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid-state laser such as a YAG laser, a semiconductor laser, or the like. Those that effectively emit ultraviolet rays and visible light are used.

((Iii) development process)
In the developing step, a resist pattern is formed on the substrate by removing at least a part of the photosensitive layer other than the photocurable portion from the substrate.

When the support is present on the photosensitive layer, the support is removed, and then the region other than the photocured portion (which can be said to be an unexposed portion) is removed (developed). There are two types of development methods, wet development and dry development, and wet development is widely used.

In the case of wet development, development is carried out by a known development method using a developer corresponding to the photosensitive resin composition. Examples of the developing method include a dip method, a paddle method, a spray method, brushing, slapping, scraping, rocking immersion, and the like, and a high-pressure spray method may be used from the viewpoint of improving resolution. .. Development may be performed by combining these two or more methods.

The composition of the developing solution is appropriately selected according to the composition of the photosensitive resin composition. Examples of the developing solution include an alkaline aqueous solution and an organic solvent developing solution.

From the viewpoint of being safe, stable, and having good operability, an alkaline aqueous solution may be used as the developer. Examples of the base of the alkaline aqueous solution include alkali hydroxides such as hydroxides of lithium, sodium or potassium; alkali carbonates such as carbonates or bicarbonates of lithium, sodium, potassium or ammonium; potassium phosphate, sodium phosphate and the like. Alkali metal phosphate; Alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; borosand, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl- 1,3-Propanediol, 1,3-diaminopropanol-2, morpholine and the like are used.

Examples of the alkaline aqueous solution used for development include a dilute solution of 0.1 to 5 mass% sodium carbonate, a dilute solution of 0.1 to 5 mass% potassium carbonate, a dilute solution of 0.1 to 5 mass% sodium hydroxide, and 0. A dilute solution of 1 to 5 mass% sodium tetraborate or the like can be used. The pH of the alkaline aqueous solution used for development may be in the range of 9 to 11, and the temperature can be adjusted according to the alkaline developability of the photosensitive layer. For example, a surface active agent, a defoaming agent, a small amount of an organic solvent for accelerating development, or the like may be mixed in the alkaline aqueous solution. Examples of the organic solvent used in the alkaline aqueous solution include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and the like. Examples thereof include diethylene glycol monobutyl ether. Examples of the organic solvent used in the organic solvent developer include 1,1,1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone and γ-butyrolactone. In order to prevent ignition, water may be added to these organic solvents so as to be in the range of 1 to 20% by mass to prepare an organic solvent developer.

In the method of forming a resist pattern in the present embodiment, after removing the uncured portion in the developing step, heating at about 60 to 250 ° C. or exposure of about 0.2 to 10 J / cm ² is performed as necessary. May include a step of further curing the resist pattern.

<Manufacturing method of printed wiring board>
The method for manufacturing a printed wiring board of the present embodiment includes a step of etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern to form a conductor pattern, and if necessary, a resist. It may be configured to include other steps such as a pattern removing step.

In the plating process, the conductor layer provided on the substrate is plated using the resist pattern formed on the substrate as a mask. After the plating treatment, the resist may be removed by removing the resist pattern described later, and the conductor layer coated with the resist may be further etched to form the conductor pattern. The plating treatment method may be an electrolytic plating treatment, an electroless plating treatment, or an electroless plating treatment.

On the other hand, in the etching process, the conductor layer provided on the substrate is removed by etching using the resist pattern formed on the substrate as a mask to form the conductor pattern. The method of etching is appropriately selected according to the conductor layer to be removed. Examples of the etching solution include a cupric chloride solution, a ferric chloride solution, an alkaline etching solution, and a hydrogen peroxide-based etching solution.

After the etching treatment or the plating treatment, the resist pattern on the substrate may be removed. The resist pattern can be removed by, for example, using a stronger alkaline aqueous solution than the alkaline aqueous solution used in the development step. As the strongly alkaline aqueous solution, for example, a 1 to 10 mass% sodium hydroxide aqueous solution, a 1 to 10 mass% potassium hydroxide aqueous solution, or the like is used.

When the resist pattern is removed after the plating treatment, a desired printed wiring board can be manufactured by further etching the conductor layer coated with the resist by the etching treatment to form the conductor pattern. The etching treatment method at this time is appropriately selected according to the conductor layer to be removed. For example, the above-mentioned etching solution can be applied.

The method for manufacturing a printed wiring board according to the present embodiment can be applied not only to the production of a single-layer printed wiring board but also to the production of a multilayer printed wiring board, and also to the production of a printed wiring board having a small-diameter through hole. It is possible.

Hereinafter, the purpose and advantages of the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples. Unless otherwise specified, "parts" and "%" are based on mass.

<Synthesis example>
(Synthesis of binder polymer (A-1))
A solution a was prepared by mixing 120 g of methacrylic acid, which is a polymerizable monomer, 380 g of styrene (mass ratio 24/76), and 0.7 g of azobisisobutyronitrile. Further, 0.6 g of azobisisobutyronitrile was mixed with a mixed solution of 45 g of methyl cellosolve and 30 g of toluene (mass ratio 3: 2) to prepare a solution b.

500 g of a mixed solution (mass ratio 3: 2) of 300 g of methyl cellosolve and 200 g of toluene was put into a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introduction tube. Next, the flask was stirred while blowing nitrogen gas into the flask, and the temperature was raised to 80 ° C.

The solution a was added dropwise to the mixed solution in the flask over 4 hours, and then the mixture was stirred at 80 ° C. for 2 hours. Then, the solution b was added dropwise to the solution in the flask over 10 minutes, and then the mixture was stirred at 80 ° C. for 2 hours. Further, the temperature of the solution in the flask was raised to 90 ° C. over 30 minutes while continuing stirring. Then, the solution b was newly added dropwise over 10 minutes, and then the mixture was stirred at 90 ° C. for 2 hours. Then, the stirring was stopped and the mixture was cooled to room temperature to obtain a solution of the binder polymer (A-1). In addition, in this specification, room temperature means 25 degreeC.

The non-volatile content (solid content) of the binder polymer (A-1) was 41.5% by mass, and the weight average molecular weight was 28,000. The weight average molecular weight was measured by gel permeation chromatography (GPC) and derived by conversion using a standard polystyrene calibration curve. The conditions of GPC are shown below. The refractive index of (A-1) is the refractive index of methacrylic acid (1.432) and the refractive index of styrene (1.547), which are the origins of the structural units, and the content (mass ratio). , And calculated as 1.519.

<GPC conditions>
Pump: Hitachi L-6000 type (Hitachi, Ltd.)
Column: A total of 3 of the following Gelpack GL-R420
Gelpack GL-R430
Gelpack GL-R440 (Hitachi Chemical Co., Ltd.)
Eluent: tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 RI (Hitachi, Ltd.)

(Synthesis of binder polymers (A-2) to (A-13))
As the polymerizable monomer (monomer), the materials shown in Table 2 below were used in the mass ratio (total amount of monomers 500 g) shown in the same table, except that the solution of the binder polymer (A-1) was obtained in the same manner as in obtaining the solution. Solutions of binder polymers (A-2) to (A-13) were obtained. The non-volatile content (solid content) of the binder polymers (A-2) to (A-13) was 41.5% by mass.

<Examples 1 to 11, 13 to 14 , Reference Example 12 and Comparative Examples 1 to 10>
[Preparation of photosensitive resin composition]
The (A) binder polymer obtained by the above method, the binder polymer (A-14) described later, the (B) photopolymerizable compound described later, (C) the photopolymerization initiator, and other components are used. , The photosensitive resin compositions (P-1 to P-22) were prepared by mixing in the blending amounts (parts by mass) shown in Table 3 below. The blending amount of the binder polymer (A) shown in Table 3 is the mass of the non-volatile component (solid content). The refractive index of the component (B) was calculated in the same manner as in the above method.

((A) Binder polymer)
A-14: Cresol novolac type carboxyl group-modified epoxy acrylate [CCR-1291H (Nippon Kayaku Co., Ltd.), does not have a structural unit derived from (meth) acrylic acid]
((B) Photopolymerizable compound)
B-1: 2,2-Bis (4- (methacryloxypentaethoxy) phenyl) propane [FA-321M (Hitachi Chemical Co., Ltd.)]
B-2: Ethoxylated bisphenol A dimethacrylate (EO average 4 mol denaturation) [BPE-200 (Shin Nakamura Chemical Industry Co., Ltd.)]
B-3: (PO) (EO) (PO) modified polyethylene glycol dimethacrylate [FA-024M (Hitachi Chemical Co., Ltd.), EO average 6 mol and PO average 12 mol modification]
B-4: Tricyclodecanedimethanol dimethacrylate [NK-DCP (Shin Nakamura Chemical Industry Co., Ltd.)]
B-5: ethoxy-modified trimethylolpropane triacrylate [Satomer SR454 (Somar Corporation)]
B-6: Trimethylolpropane Trimethacrylate [TMPT (Shin Nakamura Chemical Industry Co., Ltd.)]
((C) Photopolymerization Initiator)
C-1: 2,2'-bis (2-chlorophenyl) -4,4', 5,5'-tetraphenylbiimidazole [B-CIM (Hampford)]
C-2: Irgacure 907 [I907 (BASF)]
C-3: Irgacure 819 [I819 (BASF)]
(Other ingredients)
Sensitizer: 4,4'-diethylaminobenzophenone [EAB (Hodogaya Chemical Co., Ltd.)]
Hydrogen donor: Leuco Crystal Violet [LCV (Yamada Chemical Co., Ltd.)]
Dye: Malachite Green [MKG (Osaka Organic Chemical Industry Co., Ltd.)]
Polymerization inhibitor: tert-butylcatechol [TBC (Wako Pure Chemical Industries, Ltd.)]
Adhesion-imparting agent: Benzotriazole derivative [SF-808H (Sanwa Kasei Co., Ltd.)]

<Manufacturing of photosensitive element>
The photosensitive resin composition obtained above was applied onto a support film (support) shown below so as to have a uniform thickness. Then, it was dried in a hot air convection dryer at 70 ° C. and 110 ° C. to form a photosensitive layer having a film thickness of 25 μm after drying.

(Support film)
FB-40: PET film [Haze: 0.4%, Thickness: 16 μm, Refractive index: 1.57 to 1.60 (Toray Industries, Inc.)]
A4100: PET film [Haze: 0.2%, Thickness: 50 μm, Refractive index: 1.57 to 1.60 (Toyobo Co., Ltd.)]
G2: PET film [Haze: 2.0%, Thickness: 16 μm, Refractive index: 1.57 to 1.60 (Teijin DuPont Film Co., Ltd.)]

Examples 1 to 11 and 13 in which a polyethylene film (protective layer) (Tamapoli Co., Ltd., "NF-15") is laminated on the photosensitive layer, and the support, the photosensitive layer, and the protective layer are laminated in this order. ~ 14 , Photosensitive elements of Reference Examples 12 and Comparative Examples 1 to 10, respectively, were obtained. The combinations of the photosensitive resin composition used for producing each photosensitive element and the support film are as shown in Tables 4 and 5.

<Preparation of laminate>
A copper-clad laminate (board, Hitachi Chemical Co., Ltd., "MCL-E-679"), which is a glass epoxy material in which copper foil (thickness: 35 μm) is laminated on both sides, is applied to a surface roughening treatment liquid (Mech Co., Ltd. ), "Mech Etch Bond CZ-8100") was used for surface treatment. Then, after washing with water, pickling and washing with water, it was dried with an air stream. Then, the copper-clad laminate was heated to 80 ° C., and the photosensitive elements obtained in Examples 1 to 11, 13 to 14 , Reference Example 12 and Comparative Examples 1 to 10 were laminated on the copper surface of the copper-clad laminate. (Laminated). In the laminating, while peeling off the protective layer, the photosensitive layer of each photosensitive element was brought into contact with the copper surface of the copper-clad laminate, and a heat roll at 110 ° C. was used to obtain a crimping pressure of 0.4 MPa and 1.0 m. The roll speed was / minute. In this way, a laminated body in which the copper-clad laminate, the photosensitive layer, and the support were laminated in this order was obtained. The obtained laminate was used as a test piece in the test shown below.

<Evaluation>
(Evaluation of light sensitivity)
On the support of the test piece obtained above, a concentration region of 0.00 to 2.00 as a negative mask, a concentration step of 0.05, a tablet size of 20 mm × 187 mm, and a size of each step of 3 mm × 12 mm. A photo tool with a 41-step step tablet was placed. Next, the photosensitive layer was exposed with a predetermined amount of energy using an exposure machine equipped with a high-pressure mercury lamp (ORC Manufacturing Co., Ltd., "EXM-1201").

Next, the support film was peeled off. Next, a 1% by mass sodium carbonate aqueous solution at 30 ° C. was sprayed for twice the shortest development time (the shortest time for removing the unexposed portion) to remove the unexposed portion (development treatment).

After the development treatment, the amount of energy (mJ / cm ² ) at which the number of steps of the photocurable film step tablet formed on the substrate was 11.0 was determined, and the light sensitivity of the photosensitive resin composition was evaluated. The results are shown in Tables 4 and 5. The smaller this value is, the higher the sensitivity is.

(Evaluation of resolution and adhesion)
On the support of the test piece obtained above, a glass chrome type photo tool as a negative for resolution evaluation and a negative for adhesion evaluation (negative for resolution evaluation: line width / space width is x / x ( Adhesion of x: 1 to 30, unit: μm) wiring pattern, adhesion negative: line width / space width of y / 3y (y: 1 to 30, unit: μm) wiring pattern) I let you. Next, using an exposure machine equipped with a high-pressure mercury lamp, the photosensitive layer of the laminate was exposed with an amount of energy such that the number of remaining stages of the 41-stage step tablet was 11.0. After the exposure, it was developed in the same manner as in the above photosensitivity measurement test.

After the development process, the space portion (unexposed portion) is cleanly removed, and the line portion (exposed portion) is formed without meandering or chipping. Among the resist patterns formed, the smallest line width / space width value is used. The resolution and adhesion were evaluated. The resolution was evaluated by the minimum value of the space width, and the adhesion was evaluated by the minimum value of the line width. The results are shown in Tables 4 and 5. The smaller this value is, the better the resolution and adhesion are.

(Evaluation of defects that may occur in the resist pattern)
The resist pattern obtained in the evaluation of adhesion was observed using a scanning electron microscope (Hitachi High-Technologies Corporation, "SU-1500") at a magnification of 1000 times, and the number of resist minute defects was counted. .. In addition, 10 lines having a line width / space width of 7/21 (unit: μm) and a line length of 1 mm were observed. "A" if the number of defects with a size of 3.5 μm or more is less than 10, "B" if the number of defects is 10 or more, the number of defects is 10 or more, and the line is peeled off. Those that were partially generated were evaluated as "C". The results are shown in Tables 4 and 5.

* 1: Evaluation is not possible because the photosensitive layer could not be formed.

As is clear from Table 4, Examples 1 to 11, 13 to 14 and Reference Example 12 were excellent in resolution and adhesion.

On the other hand, Comparative Examples 1 to 10 were inferior in the balance between resolution and adhesion.

Further, in Examples 6 and 9, the resolution and adhesion were evaluated under the same conditions as above except that a photosensitive layer having a film thickness of 7 μm after drying was formed. As a result, it was found that both had a resolution of 3 μm and an adhesion of 2 μm, and had excellent resolution and adhesion. In the evaluation of defects that may occur in the resist pattern, both were "A".

According to the present disclosure, it is possible to provide, in particular, a photosensitive resin composition having excellent resolution and adhesion, a photosensitive element using the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a printed wiring board.

1 ... Photosensitive element, 2 ... Support, 3 ... Photosensitive layer, 4 ... Protective layer.

Claims (13)

It contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, and the (A) binder polymer has a structural unit derived from (meth) acrylic acid. A) The refractive index of the binder polymer is 1.504 or more.
Wherein (A) the binder polymer (B) difference in refractive index between the photopolymerizable compound (absolute value) state, and are 0.010 or less,
The refractive index of the (A) binder polymer was calculated based on the refractive index and mass ratio of each structural unit using the refractive index when the structural units from which the (A) binder polymer was derived were measured independently. Is a value
The refractive index of the (B) photopolymerizable compound is the refractive index when the photopolymerizable compound is measured alone when one kind of photopolymerizable compound is contained alone, and is a plurality of photopolymerizable compounds. When is included, the refractive index obtained by measuring each of the plurality of photopolymerizable compounds independently is used, and the entire photopolymerizable compound (B) calculated based on the refractive index and content of each photopolymerizable compound. The refractive index of the photosensitive resin composition. The photosensitive resin composition according to claim 1, wherein the binder polymer (A) further contains 65% by mass or more of structural units derived from at least one of styrene and a styrene derivative. The photosensitive resin composition according to claim 2, wherein the content of the structural unit derived from at least one of the styrene and the styrene derivative in the binder polymer (A) is 85% by mass or less. The photosensitive resin composition according to any one of claims 1 to 3, wherein the photopolymerizable compound (B) has a refractive index of 1.504 or more. The photosensitive resin composition according to claim 4, wherein the photopolymerizable compound (B) contains at least one kind of bisphenol A type (meth) acrylate having a refractive index of 1.504 or more. The photosensitive resin composition according to any one of claims 1 to 5, wherein the binder polymer (A) has a weight average molecular weight of 1000 to 80,000. The photosensitive resin composition according to any one of claims 1 to 6, wherein the photopolymerization initiator (C) contains a hexaarylbiimidazole derivative or an acridine compound having one or more acridinyl groups. The photosensitive resin according to any one of claims 1 to 7, wherein the binder polymer (A) further has a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 30 carbon atoms. Composition. A photosensitive element comprising a support and a photosensitive layer formed on the support using the photosensitive resin composition according to any one of claims 1 to 8. 9. The haze of the support is 0.01 to 1.0%, the refractive index of the support is 1.504 or more, and the support is formed by using polyethylene terephthalate. The photosensitive element described. (I) A step of forming a photosensitive layer on a substrate by using the photosensitive resin composition according to any one of claims 1 to 8 or the photosensitive element according to claim 9 or 10. ,
(Ii) A step of irradiating a predetermined portion of the photosensitive layer with active light to form a photocurable portion,
(Iii) A step of removing at least a part of the photosensitive layer other than the photocurable portion from the substrate, and
A method of forming a resist pattern. A method for manufacturing a printed wiring board, comprising a step of etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern according to claim 11 to form a conductor pattern. The method for manufacturing a printed wiring board according to claim 12, further comprising a step of removing the photocurable portion after the etching treatment or the plating treatment.

Images