WO2018100730A1

WO2018100730A1 - Photosensitive element, method for forming resist pattern and method for producing printed wiring board

Info

Publication number: WO2018100730A1
Application number: PCT/JP2016/085893
Authority: WO
Inventors: 壮和粂; 遼松村
Original assignee: 日立化成株式会社
Priority date: 2016-12-02
Filing date: 2016-12-02
Publication date: 2018-06-07
Also published as: JPWO2018100730A1; KR20190082258A; CN110023837A

Abstract

Provided is a photosensitive element 1 comprising a support film 10 and a photosensitive layer 20 disposed on the support film 10, wherein the photosensitive layer 20 contains a binder polymer, a photopolymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator, and the number of defects having diameters of 2 μm or more on a principal surface 12 on the photosensitive layer 20 side of the support film 10 is 30 or fewer per 2 mm².

Description

Photosensitive element, resist pattern forming method, and printed wiring board manufacturing method

The present invention relates to a photosensitive element, a resist pattern forming method using the same, and a printed wiring board manufacturing method.

Conventionally, as a resist material used for etching, plating, etc. in the field of printed wiring board manufacturing and precision metal processing, a support film, a layer made of a photosensitive resin composition (hereinafter referred to as “photosensitive layer”), and A photosensitive element composed of a protective film is widely used.

The printed wiring board is manufactured as follows, for example. First, after peeling off the protective film of the photosensitive element from the photosensitive layer, the photosensitive layer is laminated on the conductive film of the substrate. Next, after pattern exposure is performed on the photosensitive layer, an unexposed portion is removed with a developing solution to form a resist pattern. And a printed wiring board is formed by patterning a conductive film based on this resist pattern.

As the support film used for the photosensitive element, a support film having a defined haze value, a support film having a limited lubricant particle size, or the like may be used (for example, see Patent Documents 1 and 2 below).

Japanese Patent Laid-Open No. 2001-13681 JP 2014-74764 A

With the recent increase in resolution of circuit formation, the resolution required for the photosensitive element and the exposure apparatus used for it has increased, and resist defects derived from lubricants or aggregates of the support film of the photosensitive element (for example, resist An increase in defects such as cracks is a problem.

For example, when a highly transparent conventional support film having a sufficiently small haze value or lubricant particle size is used, a high-resolution photosensitive resin composition or a high-resolution exposure machine (for example, a projection exposure machine and a direct drawing exposure machine) ) May significantly increase resist defects.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a photosensitive element capable of suppressing the occurrence of resist defects. It is another object of the present invention to provide a method for forming a resist pattern using the photosensitive element and a method for manufacturing a printed wiring board.

Regarding resist defects in conventional photosensitive elements, defects on the surface of the support film in contact with the photosensitive layer (for example, particles such as lubricants and irregularities resulting therefrom) are the main factors that cause resist defects. This has been found by the inventors' investigation. However, it is very difficult to reduce particles such as lubricants in order to reduce defects in the resist derived from the support film, and there is a limit to the existing improved methods for reducing the size and number of particles such as lubricants. .

In contrast, the present inventor has studied in detail the influence and cause of the defects of the support film on the resist. First, in order to investigate the influence of particles in contact with the photosensitive layer, the influence of the surface in contact with the photosensitive layer on the support film on the occurrence of pattern defects was investigated using a support film coated with a lubricant on both sides. As a result, the present inventors have found the following findings. That is, it has been clarified that defects on the surface of the support film not in contact with the photosensitive layer (the surface opposite to the surface in contact with the photosensitive layer in the support film) have little influence on the resist defect. On the other hand, it has been found that resist defects can be greatly improved by smoothing the support film by reducing the number of defects on the surface in contact with the photosensitive layer.

The photosensitive element which concerns on this invention is a photosensitive element provided with a support film and the photosensitive layer arrange | positioned on the said support film, Comprising: The photosensitive layer has a binder polymer and the light which has an ethylenically unsaturated bond. It contains a polymerizable compound and a photopolymerization initiator, and the number of defects having a diameter of 2 μm or more on the surface on the photosensitive layer side of the support film is 30 or less per 2 mm ² .

In the photosensitive element according to the present invention, the number of defects on the surface of the support film on the photosensitive layer side is reduced. Thereby, since the smoothness of the surface of the support film on the photosensitive layer side is improved, the occurrence of resist defects can be suppressed. Further, according to the photosensitive element of the present invention, it is possible to suppress the occurrence of resist defects even when a high-resolution exposure machine is used, and good resist formability can be obtained.

In the photosensitive element according to the present invention, the support film has a polyester film, a resin layer, and a lubricant layer, the resin layer is disposed between the photosensitive layer and the polyester film, and the lubricant layer is polyester. The aspect arrange | positioned on the opposite side to the resin layer in a film may be sufficient. The thickness of the support film is preferably 1 to 200 μm.

The haze value of the support film is preferably 0.01 to 1.0%.

The method for forming a resist pattern according to the present invention includes a laminating step of laminating a photosensitive layer of the above-described photosensitive element on a substrate, and an exposure step of irradiating a predetermined portion of the photosensitive layer with actinic rays to form a photocured portion And a developing step for removing regions other than the photocured portion in the photosensitive layer.

The method for producing a printed wiring board according to the present invention comprises a step of applying at least one selected from the group consisting of etching treatment and plating treatment to a substrate having a resist pattern formed by the above-described resist pattern forming method. Prepare.

According to the present invention, it is possible to provide a photosensitive element capable of suppressing the occurrence of resist defects. Moreover, according to this invention, the formation method of the resist pattern using the said photosensitive element, and the manufacturing method of a printed wiring board can be provided. According to the present invention, even when a high-resolution exposure apparatus is used, it is possible to suppress the occurrence of resist defects, and good resist formability can be obtained.

It is a schematic cross section which shows one Embodiment of the photosensitive element of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as necessary. In addition, the dimensional ratio of drawing is not restricted to the ratio of illustration.

In this specification, “(meth) acrylate” means at least one of “acrylate” and “methacrylate” corresponding thereto. The same applies to other similar expressions such as “(meth) acryl”.

<Photosensitive element>
FIG. 1 is a schematic cross-sectional view showing a photosensitive element according to this embodiment. The photosensitive element 1 shown in FIG. 1 includes a support film 10 and a photosensitive layer (photosensitive resin composition layer) 20. The photosensitive layer 20 is provided on the first main surface 12 of the support film 10 and is in contact with the first main surface 12. The support film 10 has a second main surface 14 on the side opposite to the first main surface 12. Here, the first main surface 12 refers to the surface of the support film 10 on the photosensitive layer 20 side, and the second main surface 14 refers to the surface of the support film 10 opposite to the photosensitive layer 20. That means.

Conventionally, in the exposure process, when light scattering occurs due to a lubricant or a foreign substance contained in the support film, a defect occurs in the resist after development. In particular, when a high-resolution exposure machine is used, the influence of the light scattering is large, and the resist after development tends to be defective. And when the photosensitive element having such a support film is used for the production of a printed wiring board, it causes the occurrence of open defects during etching or the occurrence of short-circuit defects during plating, and the production yield of printed wiring boards is reduced. There is a tendency to decrease.

In conventional support films, the haze value is preferably 0.01 to 1.0% from the viewpoint of obtaining high transparency for the purpose of reducing resist defects. However, conventionally, for example, when the lubricant layer of the support film is present on the photosensitive layer side and a recess having a depth of 2 μm or more is formed in the photosensitive layer, resist defects are likely to occur, and a high-resolution exposure machine is used. In this case, resist defects are particularly likely to occur.

On the other hand, in the photosensitive element according to this embodiment, the number of defects having a diameter of 2 μm or more on the surface (first main surface 12) on the photosensitive layer 20 side of the support film 10 is 30 or less per 2 mm ² . As a result, the formation of a recess having a depth of 2 μm or more in the photosensitive layer 20 is suppressed, and the occurrence of resist defects can be suppressed.

(Support film)
The support film 10 has, for example, a base material layer (polyester film or the like), a resin layer, and a lubricant layer (a layer containing a lubricant). The resin layer is disposed between the photosensitive layer 20 and the base material layer, and is located on the first main surface 12 side. The resin layer may contain particles (for example, fine particles) or may be a lubricant layer (a layer containing a lubricant). The first main surface 12 of the support film 10 is preferably smooth. The lubricant layer is disposed on the side opposite to the resin layer in the base material layer, and is located on the second main surface 14 side.

The thickness of the resin layer (such as a lubricant layer) is preferably 0.05 to 5.0 μm from the viewpoint of easily maintaining the mechanical strength. The resin layer (such as a lubricant layer) can be formed using a known method such as a roll coater, a flow coater, a spray coater, a curtain flow coater, a dip coater, or a slit die coater.

The number of defects having a diameter of 2 μm or more on the first main surface 12 on the photosensitive layer 20 side of the support film 10 is 30 or less per 2 mm ² from the viewpoint of suppressing the occurrence of resist defects. The number of defects is preferably 20 or less per 2 mm ² and more preferably 10 or less from the viewpoint of further suppressing the occurrence of resist defects. The diameter of the defect is, for example, the maximum diameter of the defect. The measurement area with an area of 2 mm ² is, for example, an area of 18 mm × 0.11 mm. The number of defects is, for example, an average value of a plurality of measured values. The average value may be obtained as an average value of five measurement values obtained by measuring the number of defects in any five regions on the surface (first main surface 12) of the support film 10 on the photosensitive layer 20 side. it can. The number of defects can be measured using a polarizing microscope or optical interferometry.

The diameter of a defect (for example, particles of a lubricant or the like) included in the first main surface 12 of the support film 10 is preferably 2 μm or less. Even if many defects having a diameter of less than 2 μm are included in the support film 10, the influence on light scattering is not great. The reason for this is that when the photosensitive layer is irradiated with light in the exposure process, the photocuring reaction of the photosensitive layer is not limited to the light irradiation portion, but is slight, but in the lateral direction where light is not directly irradiated (for example, light It also proceeds in the direction perpendicular to the irradiation direction. Therefore, when the diameter is small, the photocuring reaction directly under the defect proceeds sufficiently, but as the diameter increases, the photocuring reaction directly under the defect does not proceed sufficiently, so that a fine defect of the resist occurs. Conceivable.

Here, the defect of the support film 10 is a defect derived from the components constituting the support film 10 or the like. Factors that form defects include, for example, polymer gels; monomers as raw materials; catalysts used during production; and inorganic or organic fine particles contained as necessary aggregate when the support film 10 is produced. Examples include swelling generated by applying a lubricant layer on the support film 10 and a lubricant and an adhesive; particles having a diameter of 2 μm or more (such as lubricant) contained in the support film 10. Examples of the particles having a diameter of 2 μm or more contained in the support film 10 include particles protruding from the first main surface 12 of the support film 10, particles existing inside the surface of the support film 10, and the like. The number of defects can be adjusted by selectively using particles having a small particle diameter or particles having excellent dispersibility. Here, the average particle diameter of the particles can be obtained as the median diameter (d50) of the particle size distribution measured using a laser diffraction / scattering microtrack particle size distribution meter or the like.

The support film (base material layer etc.) can be used without any particular limitation. Examples of the support film include polyethylene terephthalate (hereinafter referred to as “PET”), polyester such as polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), and polyolefin such as polypropylene and polyethylene. It is done. The support film may be a single layer or a multilayer.

The haze value of the support film is preferably 0.01 to 1.0%, more preferably 0.01 to 0.85%, still more preferably 0.01 to 0.7%. 0.01 to 0.55% is particularly preferable. When the haze value is 0.01% or more, the support film itself tends to be easily manufactured. When the haze value is 1.0% or less, the sensitivity and resolution tend to be easily suppressed. Here, the “haze value” means haze. As the haze value, a value measured using a commercially available haze meter (turbidimeter) in accordance with the method defined in JIS K 7105 can be used. The haze value can be measured with a commercially available turbidimeter such as NDH-5000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.).

The thickness of the support film is preferably 1 to 200 μm, more preferably 5 to 200 μm, still more preferably 11 to 100 μm, particularly preferably 12 to 50 μm, and 15 to 40 μm. Very preferably. When the thickness is 1 μm or more, the support film tends to be prevented from being broken when the support film is peeled from the photosensitive element. When the thickness is 200 μm or less, the price tends to be excellent.

The support film may be a commercially available general industrial film that can be used as a support film for the photosensitive element, and may be appropriately processed and used. Examples of the support film include “QS-series” (produced by Toray Industries, Inc.), which is a PET film.

(Photosensitive layer)
The photosensitive layer 20 is a layer made of a photosensitive resin composition. The photosensitive resin composition constituting the photosensitive layer 20 contains, for example, (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator. . Hereinafter, each component will be described in detail.

[(A) Binder polymer]
As the binder polymer as the component (A), a binder polymer used in a conventional photosensitive resin composition can be used without particular limitation. Examples of the binder polymer include acrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin, alkyd resin, and phenol resin. In these, an acrylic resin is preferable from a viewpoint which is excellent in alkali developability. A binder polymer can be used individually by 1 type or in combination of 2 or more types.

The binder polymer can be produced by radical polymerization of a polymerizable monomer. As the polymerizable monomer, (meth) acrylic acid, styrene, alkyl (meth) acrylate (such as methyl (meth) acrylate), benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, (meth ) Glycidyl acrylate, maleic acid and the like.

The binder polymer preferably has a carboxyl group in the molecule from the viewpoint of excellent alkali developability. The binder polymer having a carboxyl group can be produced by radical polymerization of a polymerizable monomer having a carboxyl group, and a polymerizable monomer having a carboxyl group and other polymerizable monomers , May be radically polymerized. As the polymerizable monomer having a carboxyl group, (meth) acrylic acid is preferred. As the binder polymer, a binder polymer having a structural unit derived from (meth) acrylic acid and a structural unit derived from (meth) acrylic acid alkyl ester is preferable.

The acid value of the binder polymer may be 80 to 250 mgKOH / g, 90 to 240 mgKOH / g, 100 to 230 mgKOH / g, or 100 to 200 mgKOH / g from the viewpoint of easy improvement in adhesion and resolution. The acid value of the binder polymer can be adjusted by the content of structural units constituting the binder polymer (for example, structural units derived from (meth) acrylic acid).

The weight average molecular weight (Mw) of the binder polymer may be 10,000 to 100,000, 20,000 to 80,000, or 25,000 to 60,000 from the viewpoint of easily improving the mechanical strength and resolution of the film. The weight average molecular weight can be measured, for example, by gel permeation chromatography (GPC) using a standard polystyrene calibration curve. More specifically, it can be measured under the conditions described in the examples.

The content of the binder polymer is preferably 40 to 90 parts by mass, and more preferably 50 to 80 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). When the content is 40 parts by mass or more, the photocured product tends to be suppressed from becoming brittle. When the content is 90 parts by mass or less, sufficient resolution and light sensitivity tend to be obtained.

[(B) Photopolymerizable compound having an ethylenically unsaturated bond]
The component (B) (photopolymerizable compound having an ethylenically unsaturated bond) preferably contains a compound having 4 to 40 carbon atoms of an oxyalkylene unit (alkylene glycol unit) having 2 to 6 carbon atoms. When (B) component contains such a compound, compatibility with (A) component can be improved.

Examples of the oxyalkylene unit having 2 to 6 carbon atoms include an oxyethylene unit, an oxypropylene unit, an oxyisopropylene unit, an oxybutylene unit, an oxypentylene unit, and an oxyhexylene unit. The alkylene unit is preferably at least one selected from the group consisting of an oxyethylene unit and an oxyisopropylene unit from the viewpoint of improving resolution and plating resistance.

Further, among the photopolymerizable compounds, from the viewpoint that the effects of the present invention can be obtained more reliably, from the group consisting of bisphenol A-based (meth) acrylate compounds and polyalkylene glycol di (meth) acrylates. At least one selected can be used particularly preferably.

The bisphenol A (meth) acrylate compound is preferably a compound represented by the following general formula (I).

In the general formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and preferably a methyl group. X ¹ and X ² each independently represents an alkylene group having 2 to 6 carbon atoms. p and q satisfy p + q = 1 to 40. The value of p + q is preferably 2 to 40, more preferably 4 to 40, still more preferably 5 to 30, particularly preferably 8 to 20, and preferably 8 to 16. Is very preferable, and 8 to 12 is very preferable. Note that p and q indicate the number of structural units. Therefore, an integer value is shown in a single molecule, and a rational number that is an average value is shown as an aggregate of a plurality of types of molecules. Hereinafter, the same applies to the number of structural units.

When the value of p + q is 1 or more, the compatibility with the component (A) is suppressed from decreasing, and it tends to be easily prevented from peeling off when the photosensitive element is laminated on the circuit forming substrate. When the value of p + q is 40 or less, the increase in hydrophilicity is suppressed, the resist image is hardly peeled off during development, and the plating resistance against solder plating or the like is lowered but tends to be suppressed. In either case, a reduction in the resolution of the photosensitive element tends to be suppressed.

Examples of the alkylene group having 2 to 6 carbon atoms include ethylene group, propylene group, isopropylene group, butylene group, pentylene group and hexylene group. Among these, at least one selected from the group consisting of an ethylene group and an isopropylene group is preferable from the viewpoint of improving resolution and plating resistance.

Examples of the compound represented by the general formula (I) include 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypoly). Propoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolybutoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) propane, etc. And bisphenol A-based (meth) acrylate compounds.

As 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane, 2,2-bis ( 4-((meth) acryloxypentaethoxy) phenyl) propane, 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane, and the like. Of these, 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane is commercially available as FA-321M (trade name, manufactured by Hitachi Chemical Co., Ltd.). 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane is commercially available as BPE-1300 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane is commercially available as BPE-200 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). These can be used alone or in combination of two or more.

Examples of the polyalkylene glycol di (meth) acrylate include a compound represented by the following general formula (II), a compound represented by the following general formula (III), and a compound represented by the following general formula (IV) Is mentioned. These can be used alone or in combination of two or more.

In the general formula (II), R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ¹ , m ² and n ¹ satisfy m ¹ + m ² + n ¹ = 4 to 40.

In general formula (III), R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ³ , n ² and n ³ satisfy m ³ + n ² + n ³ = 4 to 40.

In the general formula (IV), R ⁷ and R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ⁴ and n ⁴ satisfies m ⁴ + n ⁴ = 4 to 40.

Examples of the alkyl group having 1 to 3 carbon atoms in the general formulas (II), (III) and (IV) include a methyl group, an ethyl group, an n-propyl group and an isopropyl group, and a methyl group is preferable. The total number of structural units (m ¹ + m ² , m ³ and m ⁴ ) of the oxyethylene group in the general formulas (II), (III) and (IV) is preferably 1 to 30 each independently. More preferably, it is 10, more preferably 4 to 9, and particularly preferably 5 to 8. If the total number of structural units is 30 or less, sufficient tent reliability and resist shape tend to be easily obtained.

The total number (n ¹ , n ² + n ³ , and n ⁴ ) of the structural units of the oxypropylene group in the general formulas (II), (III), and (IV) is preferably independently 1 to 30, It is more preferably 5 to 20, more preferably 8 to 16, and particularly preferably 10 to 14. When the total number of the structural units is 30 or less, sufficient resolution is easily obtained, and the generation of sludge tends to be suppressed.

Specific examples of the compound represented by the general formula (II) include, for example, vinyl in which R ³ and R ⁴ are methyl groups, m ¹ + m ² = 4 (average value), and n ¹ = 1 ² (average value). A compound (trade name: FA-023M, manufactured by Hitachi Chemical Co., Ltd.).

Specific examples of the compound represented by the general formula (III) include, for example, a vinyl compound in which R ⁵ and R ⁶ are methyl groups, m ³ = 6 (average value), n ² + n ³ = 12 (average value) (Trade name: FA-024M, manufactured by Hitachi Chemical Co., Ltd.).

Specific examples of the compound represented by the general formula (IV) include a vinyl compound in which R ⁷ and R ⁸ are hydrogen atoms, m ⁴ = 1 (average value), and n ⁴ = 9 (average value) (new Nakamura Chemical Co., Ltd., trade name: NK ester HEMA-9P).

As the component (B), in addition to the compounds represented by the above general formulas (I) to (IV), a (meth) acrylate compound having a skeleton derived from dipentaerythritol can be used. The (meth) acrylate compound having a skeleton derived from dipentaerythritol means an esterified product of dipentaerythritol and (meth) acrylic acid, and the esterified product is a compound modified with an alkyleneoxy group. Is also defined as containing. Further, the number of ester bonds in one molecule is 6, but a compound having 1 to 5 ester bonds may be mixed. This compound is commercially available as DPH-12E (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.).

(B) A component can be used individually by 1 type or in combination of 2 or more types.

The content of the component (B) is preferably 10 to 60 parts by mass, and more preferably 20 to 50 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). When the content is 10 parts by mass or more, sufficient resolution and photosensitivity tend to be obtained. When the content is 60 parts by mass or less, the photocured product tends to be suppressed from becoming brittle.

[(C) Photopolymerization initiator]
Examples of the component (C) (photopolymerization initiator) include N, N, N ′ such as benzophenone; N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone (also known as Michler's ketone). , N′-tetraalkyl-4,4′-diaminobenzophenone; 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2-methyl-1- [4- (methylthio) phenyl An aromatic ketone such as 2-morpholino-1-propanone; a quinone compound such as alkyl anthraquinone; a benzoin ether compound such as benzoin alkyl ether; a benzoin compound such as benzoin and alkyl benzoin; a benzyl derivative such as benzyldimethyl ketal; (O-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chloro Enyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenyl 2,4,5-triarylimidazole dimers such as imidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer; 9-phenylacridine, 1,7-bis (9 , 9′-acridinyl) heptane derivatives; N-phenylglycine; N-phenylglycine derivatives; coumarin compounds; 1-phenyl-3- (4-methoxystyryl) -5- (4-methoxyphenyl) pyrazoline etc. And catechol compounds such as 4-t-butylcatechol. Among these, 2,4,5-triarylimidazole dimer is preferable from the viewpoint of improving adhesion and sensitivity. (C) A component can be used individually by 1 type or in combination of 2 or more types.

The content of the component (C) is preferably 0.1 to 20 parts by weight, and preferably 0.2 to 10 parts by weight with respect to 100 parts by weight as the total of the components (A) and (B). Is more preferably 0.5 to 5 parts by mass. When the content is 0.1 part by mass or more, sufficient photosensitivity tends to be obtained. When the content is 20 parts by mass or less, an increase in light absorption on the surface of the photosensitive resin composition at the time of exposure is suppressed, and an insufficient internal photocuring tends to be suppressed. is there.

[Other ingredients]
If necessary, the photosensitive resin composition comprises a photopolymerizable compound (such as an oxetane compound) having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, a dye (such as malachite green), light, and the like. Coloring agents (tribromophenyl sulfone, leuco crystal violet, etc.), thermal coloring inhibitors, plasticizers (p-toluenesulfonamide, etc.), pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion-imparting agents, You may contain additives, such as a leveling agent, peeling promoter, antioxidant, a fragrance | flavor, an imaging agent, and a thermal crosslinking agent. These can be used alone or in combination of two or more. The content of these additives may be 0.01 to 20 parts by mass with respect to 100 parts by mass of the total amount of component (A) and component (B).

The photosensitive resin composition is dissolved in a solvent such as methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, and propylene glycol monomethyl ether, or a mixed solvent thereof, as necessary. Thus, it can be prepared as a solution having a solid content of about 30 to 60% by mass.

The photosensitive layer 20 in the photosensitive element 1 can be formed by removing the solvent after applying the above-described photosensitive resin composition on the support film 10. Here, as a coating method, for example, a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating can be employed. The removal of the solvent can be performed, for example, by treating at 70 to 150 ° C. for about 5 to 30 minutes. The amount of the remaining organic solvent in the photosensitive layer 20 is preferably 2% by mass or less from the viewpoint of preventing the organic solvent from diffusing in the subsequent step.

The photosensitive element 1 may include a protective film (not shown) on the opposite side of the photosensitive layer 20 from the support film 10. As the protective film, it is preferable to use a film in which the adhesive force between the photosensitive layer 20 and the protective film is smaller than the adhesive force between the photosensitive layer 20 and the support film 10. As the protective film, a low fish eye film is preferably used. Examples of the protective film include inert polyolefin films (polyethylene, polypropylene, etc.). As the protective film, a polyethylene film is preferable from the viewpoint of excellent peelability from the photosensitive layer 20. The thickness of the protective film varies depending on the use, but is preferably about 1 to 100 μm.

The photosensitive element 1 may further include an intermediate layer or a protective layer such as a cushion layer, an adhesive layer, a light absorption layer, and a gas barrier layer in addition to the support film 10, the photosensitive layer 20, and the protective film.

The photosensitive element 1 may be stored as it is, for example, or may be stored in a state where a protective film is laminated on the photosensitive layer 20 and wound around a cylindrical core. At this time, the support film 10 is preferably wound into a roll shape so as to be the outermost layer.

<Method for forming resist pattern>
The resist pattern forming method according to the present embodiment includes a laminating step of laminating the photosensitive layer 20 of the photosensitive element 1 on a substrate, and exposure for irradiating a predetermined portion of the photosensitive layer 20 with actinic rays to form a photocured portion. And a developing step for removing regions other than the photocured portion in the photosensitive layer 20.

In the lamination step, for example, the photosensitive layer of the photosensitive element and the support film are laminated on the substrate in this order. In the laminating step, as a method of laminating the photosensitive layer 20 on the substrate, for example, when a protective film is present on the photosensitive layer 20, the protective layer is removed, and then the photosensitive layer 20 is heated to 70 to 130 ° C. There is a method of laminating by pressure bonding to the substrate at a pressure of about 0.1 to 1 MPa while heating to the extent. In the stacking step, it is also possible to stack under reduced pressure. The surface of the substrate on which the photosensitive layer 20 is laminated is usually a metal surface, but is not particularly limited. In addition, in order to further improve the stackability, the substrate may be preheated.

Next, a photomask having a negative or positive mask pattern is aligned and adhered to the second main surface 14 of the support film 10 with respect to the photosensitive layer 20 that has been laminated in the laminating step.

Next, in the exposure step, for example, a predetermined portion of the photosensitive layer 20 is irradiated through the support film 10 to form a photocured portion on the photosensitive layer 20. In the exposure step, for example, the photosensitive layer 20 is irradiated with an actinic ray in an image form through the support film 10 to form a photocured portion on the photosensitive layer 20. As the actinic light source, a known light source (for example, a light source that effectively emits ultraviolet light, visible light, etc., such as a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, or a xenon lamp) is used. A laser direct drawing exposure method can also be used.

After the exposure process, the photomask is peeled off from the support film 10. Next, the support film 10 is peeled off from the photosensitive layer 20.

Next, in the development process, the region other than the photocured portion in the photosensitive layer is removed. In the development step, for example, the unexposed portion (unphotocured portion) of the photosensitive layer 20 is removed and developed by wet development or dry development with a developer such as an alkaline aqueous solution, an aqueous developer, or an organic solvent, and a resist pattern is developed. Can be manufactured.

Examples of the alkaline aqueous solution include 0.1 to 5% by mass sodium carbonate solution, 0.1 to 5% by mass potassium carbonate solution, and 0.1 to 5% by mass sodium hydroxide solution. The pH of the alkaline aqueous solution is preferably in the range of 9-11. The temperature of the alkaline aqueous solution is adjusted according to the developability of the photosensitive layer 20. The alkaline aqueous solution may contain a surface active agent, an antifoaming agent, an organic solvent, and the like. Examples of the developing method include a dip method, a spray method, brushing, and slapping.

Further, as a treatment after the development step, the resist pattern may be further cured by performing heating at about 60 to 250 ° C. or exposure at about 0.2 to 10 J / cm ² as necessary.

By the above-described method, a resist pattern can be formed on the conductor layer on which the wiring pattern is formed. The resist pattern can be used as a solder resist for preventing solder from adhering to unnecessary portions on the conductor layer when mounting components are joined.

The resist pattern obtained by the above-described forming method is used for forming a cured resin on a rigid substrate that has excellent physical properties (tensile strength, elongation, etc.) and satisfies the electric corrosion resistance. It may be used as a permanent mask (solder resist) formed on a rigid substrate. Specifically, the resist pattern is useful when used as a solder resist for a printed wiring board having a rigid substrate or a solder resist for a semiconductor package substrate having a rigid substrate.

<Method for manufacturing printed wiring board>
The method for manufacturing a printed wiring board according to the present embodiment includes a step of applying at least one selected from the group consisting of an etching process and a plating process to a substrate having a resist pattern formed by the resist pattern forming method. Prepare. Here, the etching or plating of the substrate can be performed by etching or plating the surface of the substrate by a known method using the developed resist pattern as a mask.

As an etchant used for etching, for example, a cupric chloride solution, a ferric chloride solution, and an alkaline etching solution can be used. Examples of the plating include copper plating, solder plating, nickel plating, and gold plating.

After etching or plating, the resist pattern can be peeled off with a stronger alkaline aqueous solution than the alkaline aqueous solution used for development, for example. As the strong alkaline aqueous solution, for example, a 1 to 10% by mass aqueous sodium hydroxide solution and a 1 to 10% by mass aqueous potassium hydroxide solution are used. Examples of the peeling method include an immersion method and a spray method. The printed wiring board on which the resist pattern is formed may be a multilayer printed wiring board or may have a small diameter through hole.

When plating is performed on a substrate provided with an insulating layer and a conductor layer formed on the insulating layer, it is necessary to remove the conductor layer other than the resist pattern. As this removal method, for example, a method of lightly etching after peeling off the resist pattern; after performing the plating followed by solder plating, the resist pattern is peeled off to mask the wiring portion with solder, and then with solder The method of processing using the etching liquid which can etch only the conductor layer of the part which is not masked is mentioned.

<Semiconductor package substrate manufacturing method>
The photosensitive element which concerns on this embodiment can also be used for a semiconductor package board | substrate provided with a rigid board | substrate and the insulating film arrange | positioned on the said rigid board | substrate. In this case, the photocured portion of the photosensitive layer may be used as the insulating film. When the photocured portion of the photosensitive layer is used as, for example, a solder resist for a semiconductor package, after the development in the resist pattern forming method, ultraviolet irradiation with a high-pressure mercury lamp is performed for the purpose of improving solder heat resistance, chemical resistance, etc. Or it is preferable to heat. In the case of irradiating with ultraviolet rays, the irradiation amount can be adjusted as necessary. For example, irradiation can be performed at an irradiation amount of about 0.2 to 10 J / cm ² . When the resist pattern is heated, it is preferable that the heating is performed in the range of about 100 to 170 ° C. for about 15 to 90 minutes. Furthermore, it is also possible to perform ultraviolet irradiation and heating at the same time, and after performing one of them, the other can be performed. When ultraviolet irradiation and heating are performed simultaneously, heating to 60 to 150 ° C. is more preferable from the viewpoint of effectively imparting solder heat resistance, chemical resistance, and the like.

This solder resist is effective as a permanent mask for semiconductor packages because it also serves as a protective film for wiring after soldering to the substrate, and has excellent physical properties (tensile strength, elongation, etc.) and thermal shock resistance. is there.

The semiconductor package substrate having such a resist pattern is mounted on an electronic device such as a personal computer after mounting of a semiconductor element or the like (for example, wire bonding and solder connection).

According to the photosensitive element, the resist pattern forming method, the printed wiring board, and the semiconductor package substrate manufacturing method according to the present embodiment, in the photosensitive element including the support film, the surface on the photosensitive layer side of the support film (the first layer) Since the number of defects in the main surface 12) is reduced, resist defects can be sufficiently reduced. In particular, when a high-resolution exposure machine is used, the resist defects can be reduced.

Incidentally, the depth of focus (focal range) of the exposure apparatus for forming a fine circuit is, for example, ± 40 μm when a resolution of 4 μm is obtained, and ± 10 μm when a resolution of 2 μm or less is obtained. Thus, when a fine circuit (high resolution) is obtained, the depth of focus becomes narrow. Here, if a lubricant layer (for example, the lubricant layer disposed on the second main surface 14 side in FIG. 1) is disposed at a position outside the range of the focal depth, defects are likely to be reduced. Moreover, when the surface (for example, the 1st main surface 12 of FIG. 1) which contact | connects a photosensitive layer is contained in the range of a focal depth, it is preferable that the said surface is smooth.

As mentioned above, although this invention was demonstrated in detail based on the embodiment, this invention is not limited to the said embodiment. The present invention can be variously modified without departing from the gist thereof.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Synthesis of binder polymer>
The binder polymer having the composition shown in Table 1 was synthesized according to the following synthesis example.

To a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen gas introduction tube was added 420 g of toluene and methyl cellosolve having a mass ratio of 6: 4, followed by stirring while blowing nitrogen gas. And heated to 80 ° C. In addition, a solution (hereinafter referred to as “solution a”) in which the predetermined materials shown in Table 1 were mixed as a comonomer was prepared, and the compound (toluene: methyl cellosolve = mass ratio 6) heated to 80 ° C. Solution 4a was added dropwise to 4) over 4 hours. Then, the dropping funnel was washed with 40 g of a mixture of toluene and methyl cellosolve having a mass ratio of 6: 4 and added to the flask. Next, the mixture was kept at 80 ° C. with stirring for 2 hours. Furthermore, a solution in which 1.0 g of azobisisobutyronitrile was dissolved in 40 g of a mixture of methyl cellosolve and toluene having a mass ratio of 6: 4 was dropped into the flask over 30 minutes. The dropping funnel was washed with 120 g of a mixture of toluene and methyl cellosolve having a mass ratio of 6: 4 and added to the solution a. The solution after dropping was kept at 80 ° C. for 3 hours with stirring, and then heated to 90 ° C. over 30 minutes. The mixture was kept at 90 ° C. for 2 hours and then cooled to obtain a binder polymer solution as component (A). Toluene was added to the binder polymer solution to adjust the nonvolatile component concentration (solid content concentration) to 40% by mass. The weight average molecular weight of the binder polymer was measured. The weight average molecular weight was measured by a gel permeation chromatography (GPC) method and calculated by using a standard polystyrene calibration curve. The GPC conditions are shown below. The acid value was measured according to the following measurement procedure. Table 1 shows the measurement results of the weight average molecular weight and acid value.

[GPC conditions]
Pump: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 (3 in total) [above, manufactured by Hitachi Chemical Co., Ltd., trade name]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI [manufactured by Hitachi, Ltd., trade name]

[Measurement method of acid value]
After the synthesized binder polymer solution was weighed in an Erlenmeyer flask, a mixed solvent (mass ratio: toluene / methanol = 70/30) was added to dissolve the binder polymer. Next, after adding a phenolphthalein solution as an indicator, the solution was titrated with a 0.1N potassium hydroxide alcohol solution to measure the acid value.

<Preparation of solution of photosensitive resin composition>
Each component shown in the following Table 2 was blended to prepare a photosensitive resin composition solution.

<Production of photosensitive element>
As the support film for the photosensitive element, the support film shown in Table 3 (“film name” in Table 3) was prepared. Details of each support film are as follows.

QS series: A biaxially oriented film having a three-layer structure having a PET film and a lubricant layer (resin layer containing particles) disposed on both sides of the PET film. The number of lubricants contained in one lubricant layer is extremely small compared to the other lubricant layer; FB-40 manufactured by Toray Industries, Inc .: PET film and a lubricant layer (resin containing particles) disposed on both sides of the PET film A biaxially oriented film having a three-layer structure having an average particle diameter of particles of 1 μm or less; manufactured by Toray Industries, Inc. A-1517: PET film and a first film disposed on one side of the PET film A lubricant layer (resin layer containing particles) and a second lubricant layer (resin layer containing particles; average particle diameter of contained particles: 2 μm or more) disposed on the other surface of the PET film. A biaxially oriented film having a two-layer structure: A-4100 manufactured by Toyobo Co., Ltd., a PET film, a first lubricant layer (resin layer containing particles) arranged on one surface of the PET film, and the PET film A biaxially oriented film having a two-layer structure having a second lubricant layer (resin layer containing particles; average particle diameter of contained particles: 2 μm or more) disposed on the other side of the rumm; G2H manufactured by Toyobo Co., Ltd. : Biaxially oriented PET film having a single layer structure containing particles (average particle size: 2 μm or more); manufactured by Teijin DuPont Films Ltd.

Table 3 shows the results of measuring the thickness of the support film, the number of defects having a diameter of 2 μm or more on the surface of the support film, the transmittance, and the haze value. The number of defects was determined by using light interference to measure the number of defects (aggregate particles, etc.) having a diameter of 2 μm or more present in an area of 2 mm ² (18 mm × 0.11 mm). As a measuring machine, a trade name “Hybrid Confocal Microscope” manufactured by Lasertec Corporation was used. The number of measurements (n number) at that time was set to 5, and the average value was calculated. The surface on which the photosensitive layer is formed (first main surface 12 in FIG. 1; “surface on the photosensitive layer side” in Table 3) and the surface opposite to the surface on which the photosensitive layer is formed (in FIG. 1) Second main surface 14. In Table 3, the number of defects in “surface opposite to photosensitive layer”) was measured. The transmittance and haze value were measured using a haze meter NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

Next, after the solution of the photosensitive resin composition was applied on each support film so as to have a uniform thickness, the solvent was removed by drying with a hot air convection dryer at 100 ° C. for 2 minutes. When A-1517 or A-4100 was used as the support film, a photosensitive layer was formed on the second lubricant layer (resin layer containing particles; average particle diameter of contained particles: 2 μm or more). After drying, the photosensitive layer was covered with a protective film made of polyethylene (manufactured by Tamapoly Co., Ltd., trade name “NF-15A”, thickness: 28 μm) to obtain a photosensitive element. The photosensitive layer after drying had a thickness of 10 μm.

<Production of laminate>
The copper surface of a double-sided copper-clad laminate (made by Hitachi Chemical Co., Ltd., trade name “MLC-E-679”, 125 mm × 200 mm square) made of glass epoxy material with copper foil (thickness: 35 μm) laminated on both sides is acidified After washing and washing with water, it was dried with an air stream. The obtained copper-clad laminate was heated to 80 ° C., and then the photosensitive element was laminated so that the photosensitive layer was in contact with the copper surface while peeling off the protective film. Thereby, the laminated body laminated | stacked in order of the copper clad laminated board, the photosensitive layer, and the support film was obtained. Lamination was performed using a 110 ° C. heat roll at a pressure of 0.4 MPa and a roll speed of 1.5 m / min.

<Evaluation>
(Measurement of minimum development time)
The photosensitive layer of the test piece (laminate) was exposed at 250 mJ / cm ² using a projection exposure machine (UX-7 series, manufactured by USHIO INC.) Having a high-pressure mercury lamp, and then the support film was peeled off. Next, the photosensitive layer was spray-developed, and the time during which the unexposed area was completely removed was measured to obtain the minimum development time. Table 3 shows the measurement results.

(Measurement of light sensitivity)
A 41-step tablet was placed as a negative on the support film of the test piece (laminate). Then, using a projection exposure machine with a high-pressure mercury lamp (UX-7 series, manufactured by Ushio Electric Co., Ltd.), the amount of irradiation is adjusted in order to obtain a predetermined amount of irradiation energy at which the number of resist curing steps after development is nine. While exposing the photosensitive layer.

Next, the support film was peeled off, and a 1% by mass sodium carbonate aqueous solution at 30 ° C. was spray-developed in a time twice as long as the minimum development time, and the unexposed portion was removed for development. And it confirmed that the number of steps of the step tablet of the photocured film formed on the copper clad laminate was 9, and the irradiation energy amount (exposure amount, mJ / cm ² ) in the exposure was obtained. Table 3 shows the measurement results. It shows that photosensitivity is so high that the value of irradiation energy amount is small.

(Measurement of adhesion and resolution)
In order to check the adhesion and resolution, a photo tool having a 41-step tablet and a glass chrome type having a wiring pattern with a line width / space width of 2/6 to 20/90 (unit: μm) as a negative for adhesion evaluation , A glass chrome type photo tool having a wiring pattern with a line width / space width of 2/2 to 20/20 (unit: μm) as a negative for resolution evaluation, and a projection exposure machine (UX) having a high-pressure mercury lamp -7 series (manufactured by Ushio Electric Co., Ltd.) was used to expose the photosensitive layer of the laminate with an irradiation energy amount such that the number of remaining steps after development of the 41-step tablet was 9 steps. Next, the support film was peeled off, and a 1% by mass aqueous sodium carbonate solution was spray-developed at 30 ° C. in a time twice as long as the minimum development time, and the unexposed portion was removed for development. Here, the adhesion and resolution were evaluated by the smallest value (unit: μm) of the space width between the line widths in which the unexposed portion could be removed cleanly by the development process. In addition, evaluation of adhesiveness and resolution is so favorable that a numerical value is small. The results are shown in Table 3.

(Evaluation of resist defect)
Using a scanning electron microscope SU-1500 (manufactured by Hitachi, Ltd.), the resist lines of the substrate used in the measurement of adhesion and resolution were observed, and the number of resist defects per 2 mm ² was evaluated. The results are shown in Table 3.

When exposure was performed at a low curing step number so that ST = 9/41 with a high-resolution projection exposure machine, resist defects were not confirmed in Examples 1 to 3, whereas in Comparative Examples 1 to 4, The defect | deletion of the resist considered to originate in the lubricant of a support film, etc. was confirmed.

The particle size of the lubricant of the supporting film used in Comparative Example 1 is smaller than the particle size of the lubricant contained in Comparative Examples 2 to 4, but at the interface between the photosensitive layer and the supporting film (the surface on the photosensitive layer side of the supporting film). Since there are a large number of defects derived from a lubricant or the like, it is considered that the defects block the exposure light beam and cause resist defects. In Comparative Examples 2 and 3, since the number of lubricants present at the interface between the photosensitive layer and the support film (the surface on the photosensitive layer side of the support film) is large, the aggregate blocks the exposure light beam and causes a resist defect. Conceivable.

According to the present invention, it is possible to provide a photosensitive element capable of suppressing the occurrence of resist defects. Moreover, according to this invention, the formation method of the resist pattern using the said photosensitive element, and the manufacturing method of a printed wiring board can be provided.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 10 ... Support film, 12 ... 1st main surface (surface on the photosensitive layer side of a support film), 14 ... 2nd main surface (surface on the opposite side to the photosensitive layer of a support film), 20: Photosensitive layer (photosensitive resin composition layer).

Claims

A photosensitive element comprising a support film and a photosensitive layer disposed on the support film,
The photosensitive layer contains a binder polymer, a photopolymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator,
Wherein the number of light-sensitive layer side diameter 2μm or more defects in the surface of more than 30 per 2 mm 2, the photosensitive element of the support film.
The support film has a polyester film, a resin layer, and a lubricant layer,
The resin layer is disposed between the photosensitive layer and the polyester film;
The photosensitive element of Claim 1 with which the said lubricant layer is arrange | positioned on the opposite side to the said resin layer of the said polyester film.
3. The photosensitive element according to claim 1, wherein the support film has a thickness of 1 to 200 μm.
The photosensitive element according to any one of claims 1 to 3, wherein the support film has a haze value of 0.01 to 1.0%.
A laminating step of laminating the photosensitive layer of the photosensitive element according to any one of claims 1 to 4 on a substrate;
An exposure step of irradiating a predetermined portion of the photosensitive layer with actinic rays to form a photocured portion;
A development step of removing a region other than the photocured portion in the photosensitive layer.
A method for producing a printed wiring board, comprising a step of applying at least one selected from the group consisting of etching treatment and plating treatment to a substrate having a resist pattern formed by the method for forming a resist pattern according to claim 5 .