JP5768521B2 - Photosensitive element, resist pattern forming method using the same, and printed wiring board manufacturing method - Google Patents

Description

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

  Conventionally, in the field of printed wiring board manufacturing and metal precision processing, the resist material used for etching, plating, etc. is composed of a photosensitive resin composition layer (hereinafter referred to as “photosensitive layer”), a support film and a protective film. The photosensitive element to be used is widely used (see Patent Documents 1 to 8).

  A 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 circuit forming substrate. Next, after pattern exposure is performed on the photosensitive layer, an unexposed portion (unexposed portion) of the photosensitive layer 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.

  In recent years, the contact area between a circuit-forming substrate and a photosensitive layer that is a resist material has been reduced with the increase in the density of printed wiring boards. Therefore, the photosensitive resin composition for forming the photosensitive layer is required to have excellent mechanical strength, chemical resistance and flexibility in the etching or plating process. In addition, excellent adhesion to a circuit forming substrate and excellent resolution in pattern formation are required. For example, a photosensitive resin composition containing a binder polymer having a specific structure for the purpose of excellent plating resistance has been disclosed (see Patent Documents 9 and 10).

  Usually, when forming a resist using a photosensitive element, a photosensitive layer is laminated on a substrate, and then the photosensitive layer is exposed through a support film. Therefore, in order to obtain high resolution in pattern formation, it is necessary to consider not only the photosensitive resin composition but also the properties of the support film to be used.

  In order to obtain a high resolution, for example, the haze of the support film is lowered by including inorganic or organic fine particles having an average particle size of about 0.01 to 5 μm on one outermost surface of the support film, and the support film is exposed to light. A method that can increase the resolution even when the layer is exposed has been proposed (see, for example, Patent Documents 11 to 14).

JP-A-01-221735 Japanese Patent Laid-Open No. 02-230149 Japanese Examined Patent Publication No. 56-040824 JP 55-501072 A JP-A-47-000469 JP 59-097138 A JP 59-216141 A JP-A 63-197942 JP 2006-234959 A JP 2008-039978 A Patent No. 4014872 International Publication No. 08/093643 Japanese Patent Application Laid-Open No. 07-333853 International Publication No. 00/079344

  However, with the conventional method, it is possible to suppress a decrease in resolution of the photosensitive layer due to the influence of the support film and a defect in the resist shape after curing (resist defect), but it has been required for recent photosensitive elements. In order to satisfy the characteristics, further improvements are required.

  Moreover, there is a limit in achieving the developability and resolution required in recent years only by combining the conventional photosensitive resin composition with the support film described in Patent Documents 11 to 14, and there is room for further improvement. It is left.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photosensitive element that can sufficiently reduce resist defects and has excellent developability and resolution in pattern formation. And

The present invention is a photosensitive element comprising a support film and a photosensitive resin composition layer formed on the support film, wherein the haze of the support film is 0.01 to 2.0%, and The total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more contained in the support film is 5 / mm ² or less, and the photosensitive resin composition layer has a binder polymer and an ethylenically unsaturated bond. A photosensitive element containing a polymerizable compound and a photopolymerization initiator, wherein the binder polymer has an acid value x of 60 to 130 mgKOH / g and a weight average molecular weight Mw satisfying a relationship represented by the following formula (I): I will provide a.

10,000 ≦ Mw <4000e ^0.02x (I)
In formula (I), x represents the acid value of the binder polymer, and Mw represents the weight average molecular weight of the binder polymer.

  The photosensitive element which concerns on this invention can fully reduce a resist defect | deletion by providing the support film which has the said structure. Moreover, the photosensitive element which concerns on this invention can fully reduce a resist defect | deletion by providing the photosensitive resin composition layer which has the said structure, and has the outstanding developability and resolution in pattern formation. .

  In the photosensitive element of the present invention, the photopolymerizable compound having an ethylenically unsaturated bond preferably contains a compound represented by the following general formula (II).

In general formula (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, Y represents an alkylene group having 2 to 6 carbon atoms, and n ¹ and n ² each independently represents a positive integer. N ¹ + n ² is 4 to 40, and a plurality of Y may be the same as or different from each other.

  By containing the compound represented by the general formula (II), the balance of adhesion, resolution, and chemical resistance is improved, and a very fine resist pattern can be formed.

  In the photosensitive element of the present invention, the binder polymer preferably has a divalent group represented by the following general formulas (III), (IV) and (V). Thereby, the balance with adhesiveness, resolution, and peelability becomes better, and it becomes possible to form an extremely fine-line resist pattern.

In the general formulas (III), (IV) and (V), R ³ , R ⁴ and R ⁶ each independently represent a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 4 carbon atoms and 1 carbon atom. Represents an alkoxy group of ˜3, a hydroxyl group or a halogen atom, R ⁷ represents an alkyl group having 1 to 10 carbon atoms, p represents an integer of 0 to 5, and when p is 2 or more, a plurality of R ⁵ are present. They may be the same or different from each other.

  In the photosensitive element of the present invention, the binder polymer further preferably has a divalent group represented by the following general formula (VI). Thereby, the balance of adhesiveness, resolution, and peelability is further improved.

In the general formula (VI), R ¹⁵ represents a hydrogen atom or a methyl group, R ¹⁶ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxyl group or a halogen atom, and q represents 0 to 0 5 represents an integer of 5 and when q is 2 or more, a plurality of R ¹⁶ may be the same as or different from each other.

  In the photosensitive element of the present invention, the photopolymerization initiator preferably contains a 2,4,5-triarylimidazole dimer. As a result, it is possible to form an extremely fine-line resist pattern with excellent adhesion and resolution while maintaining photosensitivity.

  The present invention also provides a lamination step of laminating the photosensitive element on the circuit-forming substrate in the order of the photosensitive resin composition layer and the support film, and an actinic ray through the support film. A resist pattern comprising: an exposure step of irradiating a predetermined portion of the physical layer to form a photocured portion in the photosensitive resin composition layer; and a developing step of removing the photosensitive resin composition layer other than the photocured portion A forming method is provided. According to the method for forming a resist pattern of the present invention, since the photosensitive element of the present invention is used, a resist pattern of ultra fine wires can be obtained efficiently.

  Moreover, this invention provides the manufacturing method of a printed wiring board which has the process of etching or plating with respect to the circuit formation board | substrate with which the resist pattern was formed, and the printed wiring board manufactured by the said manufacturing method. According to the method for producing a printed wiring board of the present invention, since the resist pattern forming method using the photosensitive element of the present invention is employed, a high-density printed wiring board having an ultrafine wiring pattern is obtained. be able to.

  According to the photosensitive element of the present invention, it is possible to provide a photosensitive element that can sufficiently reduce resist defects and has excellent developability and resolution in pattern formation.

It is a schematic cross section which shows suitable embodiment of the photosensitive element of this invention. It is the polarizing microscope photograph which observed the surface of the support film which has particle | grains etc. with a diameter of 5 micrometers or more. It is a scanning microscope picture of the resist pattern formed using the photosensitive element provided with a photosensitive layer on the support film which has many particle | grains with a diameter of 5 micrometers or more.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios. In addition, “(meth) acrylate” in the present specification means “acrylate” and “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” and “methacryl” corresponding thereto, and “(meth) acryloyl” means “acryloyl” and corresponding “methacryloyl”.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the photosensitive element of the present invention. 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. The support film 10 has a second main surface 14 on the side opposite to the first main surface 12.

(Support film)
The support film 10 has a haze of 0.01 to 2.0%, and the total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more (hereinafter simply referred to as “particles”) included in the support film 10. 5 / mm ² or less. Here, particles or the like having a diameter of 5 μm or more included in the support film 10 protrude from the first main surface 12 and the second main surface 14 of the support film 10 and are present inside the film 10. Both things are included. In addition, particles having a diameter of 5 μm or more include aggregates of primary particles having a diameter of 5 μm or more and primary particles having a diameter of less than 5 μm.

The total number of particles having a diameter of 5 μm or more is preferably 5 pieces / mm ² or less, more preferably 3 pieces / mm ² or less in terms of reducing partial defects in the resist after exposure and development. More preferably, it is 1 piece / mm ² or less. If a photosensitive element with a total number of particles exceeding 5 / mm ² is used in the production of a printed wiring board, it will cause the occurrence of open defects during etching and short circuit defects during plating. There is a tendency for the manufacturing yield of the wiring board to decrease.

  Even if many particles having a diameter of less than 5 μm are included in the support film 10, the influence on light scattering is not great. The reason for this is that, in the exposure process described later, when the photosensitive layer 20 is irradiated with light, the photocuring reaction of the photosensitive layer 20 is not limited to the light-irradiated portion, but a slight amount of light is not directly irradiated (light It also proceeds in the direction perpendicular to the irradiation direction. For this reason, when the particle size is small, the photocuring reaction immediately below the particles proceeds sufficiently. However, as the particle size increases, the photocuring reaction directly below the particles does not proceed sufficiently. ) Is considered to occur.

Here, the particles having a diameter of 5 μm or more contained in the support film 10 are components constituting the support film 10, for example, a polymer gel, a raw material monomer, a catalyst used in production, and as necessary. Agglomerates formed by aggregation of inorganic or organic fine particles contained during film production, swelling caused by a lubricant and an adhesive generated when a lubricant-containing layer is applied on the film, particles having a diameter of 5 μm or more contained in the film, etc. It is caused by this. In order to reduce the total number of particles having a diameter of 5 μm or more to 5 particles / mm ² or less, among these particles, particles having a small particle diameter or excellent dispersibility may be selectively used.

  The total number of particles having a diameter of 5 μm or more can be measured using a polarizing microscope. In addition, the aggregate formed by aggregating primary particles having a diameter of 5 μm or more and primary particles having a diameter of less than 5 μm is counted as one. FIG. 2 is a polarization micrograph observing the surface of the support film having particles having a diameter of 5 μm or more. In FIG. 2, a portion surrounded by a circle indicates an example of a portion corresponding to a particle having a diameter of 5 μm or more. FIG. 3 is a scanning photomicrograph of a resist pattern formed using a photosensitive element having a photosensitive layer on a support film having a large number of particles having a diameter of 5 μm or more. A portion surrounded by a frame indicates a location where the resist is missing. Thus, if there are a large number of particles having a diameter of 5 μm or more on the surface of the support film, a resist defect occurs.

The material of the support film 10 is not particularly limited as long as the total number of particles having a diameter of 5 μm or more is 5 / mm ² or less. Examples of the support film 10 include a film containing at least one resin material selected from the group consisting of polyesters such as polyethylene terephthalate (hereinafter referred to as “PET”) and polyolefins such as polypropylene and polyethylene. .

  The support film 10 may be a single layer or a multilayer. For example, when a two-layer support film consisting of two layers is used, a two-layer film obtained by laminating a resin layer containing fine particles on one surface of a biaxially oriented polyester film is used as the support film, and contains the fine particles. The photosensitive layer 20 is preferably formed on the surface opposite to the surface on which the resin layer is formed. Further, as the support film 10, a multilayer support film composed of three layers (for example, A layer / B layer / A layer) can also be used. The configuration of the multilayer support film is not particularly limited, but from the standpoint of film slipperiness and the like, the outermost layer (A layer in the case of the above three layers) is preferably a resin layer containing fine particles.

  Since the conventional two-layer support film is manufactured by applying a resin layer having fine particles to a biaxially oriented polyester film, the resin layer containing fine particles is easily peeled off when the photosensitive layer is laminated, and the peeled resin layer is It may adhere to the photosensitive layer and cause defects. Therefore, in this embodiment, it is preferable to use a multilayer support film composed of three layers composed of a resin layer containing fine particles and a biaxially oriented polyester film.

In the present embodiment, the total number of particles having a diameter of 5 μm or more contained in the support film 10 is adjusted to 5 / mm ² or less, and at the same time, the multilayer support film includes a resin layer containing such fine particles. Particularly preferred. Thereby, the slipperiness of the film is improved, and the suppression of light scattering at the time of exposure can be achieved in a balanced manner at a higher level. The average particle diameter of the fine particles is preferably 0.1 to 10 times, more preferably 0.2 to 5 times the thickness of the resin layer containing the fine particles. If the average particle size is less than 0.1 times, the slipping property tends to be inferior, and if it exceeds 10 times, the photosensitive layer tends to be particularly uneven.

  The fine particles are preferably contained in the resin layer containing fine particles in an amount of 0.01 to 50% by mass based on the mass of the resin. Examples of the fine particles include fine particles generated during polymerization with various nucleating agents, aggregates, fine particles of silicon dioxide (aggregated silica, etc.), fine particles of calcium carbonate, fine particles of alumina, fine particles of titanium oxide, and fine particles of barium sulfate. Inorganic fine particles such as crosslinked fine particles of polystyrene resin, fine organic particles such as fine particles of acrylic resin and fine particles of imide resin, and mixtures thereof can be used.

  In the multilayer support film having three or more layers, the one or more intermediate layers sandwiched between the outermost layers containing fine particles may or may not contain the fine particles. From the standpoint, it is preferable that the fine particles are not contained. When the intermediate layer contains the fine particles, the content in the intermediate layer is preferably 1/3 or less of the content of the outermost layer, and more preferably 1/5 or less.

  The layer thickness of the resin layer containing the fine particles is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm, and more preferably 0.1 to 2 μm from the viewpoint of excellent resolution. It is particularly preferred. And it is preferable that the surface which does not oppose the intermediate | middle layer of outermost layer has a static friction coefficient of 1.2 or less. If the coefficient of static friction exceeds 1.2, wrinkles tend to occur during film production and photosensitive element production, and dust tends to adhere because it tends to generate static electricity. In the present embodiment, the static friction coefficient can be measured according to ASTM D1894.

In order to set the total number of particles having a diameter of 5 μm or more contained in the support film 10 to 5 particles / mm ² or less, the particle size of the fine particles contained in the resin layer containing fine particles is preferably less than 5 μm. . In order to further reduce light scattering during exposure, it is preferable to appropriately adjust the thickness of the resin layer containing fine particles in accordance with the particle size of the fine particles.

  In addition, the support film 10 may contain an antistatic agent or the like as necessary as long as the photosensitivity of the photosensitive layer 20 is not impaired.

  The haze of the support film 10 is preferably 2.0% or less, more preferably 1.5% or less, and preferably 1.0% or less in terms of excellent photosensitivity and resolution. More preferably, it is particularly preferably 0.5% or less. Here, “haze” means haze. The haze of the support film 10 in the present embodiment refers to a value measured using a commercially available haze meter (turbidimeter) in accordance with a method defined in JIS K 7105. The haze can be measured with a commercially available turbidimeter, for example, NDH-1001DP (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.). The lower limit of the haze is preferably close to zero in terms of excellent photosensitivity and resolution, but the haze is set to 0.01 or more from the viewpoint of winding property at the time of producing the support film 10. Is preferred. When the haze is less than 0.01, the support film does not contain fine particles or the like, which tends to hinder winding during production of the support film and cause wrinkles.

  The thickness of the support film 10 is preferably 5 to 40 μm, more preferably 8 to 35 μm, particularly preferably 10 to 30 μm, and further preferably 12 to 25 μm. When the thickness is less than 5 μm, the support film tends to be easily broken when the support film is peeled from the photosensitive element. On the other hand, when the thickness exceeds 40 μm, the resolution tends to be lowered and the inexpensiveness tends to be insufficient.

  In addition, the support film 10 may be obtained by using a film that can be used as the support film 10 of the photosensitive element 1 from commercially available general industrial films, and may be appropriately processed and used. Examples of commercially available general industrial films that can be used as the support film 10 include “QS-48” (trade name, manufactured by Toray Industries, Inc.), which is a three-layer PET film whose outermost layer contains fine particles. .

(Photosensitive layer)
The photosensitive layer 20 is a layer made of a photosensitive resin composition. The photosensitive resin composition constituting the photosensitive layer 20 includes (A) a binder polymer (hereinafter referred to as “component (A)”), (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) photopolymerization. Contains an initiator (hereinafter referred to as “component (C)”). Hereafter, each said component is demonstrated in detail.

(Binder polymer)
The binder polymer as the component (A) is not particularly limited as long as the acid value x is 60 to 130 mgKOH / g and the weight average molecular weight Mw satisfies the relationship represented by the following formula (I). Can be used.
10,000 ≦ Mw <4000e ^0.02x (I)

  When the relationship between the acid value x of the binder polymer and the weight average molecular weight Mw satisfies the relationship of the above formula, various properties after development (developability, adhesion, resolution, resist side shape and resist defect) An excellent photosensitive resin composition can be provided.

  The acid value x of the binder polymer is 60 to 130 mgKOH / g, but it is preferably 65 to 130 mgKOH / g, more preferably 90 to 130 mgKOH / g, in terms of satisfying the above-mentioned various properties in a balanced manner. More preferably, it is 110-130 mgKOH / g.

  As an index similar to the acid value (mg number of potassium hydroxide (KOH) required to neutralize 1 g of sample), acid equivalent (g number of polymer having 1 equivalent of carboxylic acid) can be mentioned. They can be converted into each other.

The weight average molecular weight of the binder polymer satisfies the relationship represented by the above formula (I). The lower limit of Mw of the binder polymer is 10,000 or more, and is preferably 15000 or more, more preferably 20000 or more, and further preferably 25000 or more in terms of excellent toughness of the photosensitive layer. Further, the upper limit value of Mw of the binder polymer is 4000e ^0.02x or less, and 90% or less of 4000e ^0.02x is preferable and 80% or less in terms of satisfying various properties after curing. Is more preferable, and it is still more preferable that it is 70% or less. The weight average molecular weight is measured by gel permeation chromatography (hereinafter referred to as “GPC”), and a value converted to standard polystyrene is used, and the measurement conditions are described in Examples described later. The conditions are the same.

  Examples of the binder polymer include acrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin, alkyd resin, and phenol resin. Among these, an acrylic resin is preferable from the viewpoint of alkali developability. These can be used alone or in combination of two or more.

  The binder polymer can be produced, for example, by radical polymerization of a polymerizable monomer. Polymerizable monomers include polymerizable styrene derivatives such as styrene, vinyltoluene, p-methylstyrene, p-chlorostyrene, α-methylstyrene and α-methylstyrene derivatives, acrylamide, acrylonitrile and vinyl-n-butyl. Esters of vinyl alcohol such as esters, (meth) acrylic acid alkyl esters, (meth) acrylic acid benzyl esters, (meth) acrylic acid tetrahydrofurfuryl esters, (meth) acrylic acid dimethylaminoethyl esters, (meth) acrylic acid (Meth) acrylic acid esters such as diethylaminoethyl ester, (meth) acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth) acrylate and 2,2,3,3-tetrafluoropropyl (meth) acrylate, (Meta) (Meth) acrylic acid derivatives such as acrylic acid, α-bromo (meth) acrylic acid, α-chloro (meth) acrylic acid, β-furyl (meth) acrylic acid and β-styryl (meth) acrylic acid, maleic acid, Maleic acid derivatives such as maleic anhydride, monomethyl maleate, monoethyl maleate and monoisopropyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. These can be used alone or in combination of two or more.

  The binder polymer preferably contains structural units represented by the following general formulas (III), (IV) and (V) from the viewpoint of the balance between the resistance to the developer (developer resistance) and the peelability. Note that the adhesion and resolution tend to be improved due to the improvement of the developer resistance.

In the general formulas (III), (IV) and (V), R ³ , R ⁴ and R ⁶ each independently represent a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 4 carbon atoms and 1 carbon atom. Represents an alkoxy group of ˜3, a hydroxyl group or a halogen atom, R ⁷ represents an alkyl group having 1 to 6 carbon atoms, p represents an integer of 0 to 5, and when p is 2 or more, a plurality of R ⁵ are present. They may be the same or different from each other.

The structural unit represented by the general formula (III) is a structural unit based on (meth) acrylic acid, and is preferably a structural unit based on methacrylic acid (R ³ = methyl group).

  (A) When a binder polymer contains the structural unit represented by the said general formula (III), the content rate is developability and peeling on the basis of the solid content whole quantity of the (A) binder polymer which is a copolymer. In terms of excellent properties, the content is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. Further, in terms of excellent adhesion and resolution, the content is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 35% by mass or less.

The structural unit represented by the general formula (IV) includes styrene (R ⁴ = hydrogen atom, p = 0), styrene derivative, α-methylstyrene (R ⁴ = methyl group, p = 0), and α-methylstyrene. A structural unit based on a derivative. In the present embodiment, “styrene derivative” and “α-methylstyrene derivative” mean that the hydrogen atom in the benzene ring of styrene and α-methylstyrene is a substituent R ⁵ (an alkyl group having 1 to 4 carbon atoms, 1 carbon atom). -3 alkoxy group, hydroxyl group, halogen atom). Examples of the styrene derivative include methyl styrene, ethyl styrene, tert-butyl styrene, methoxy styrene, ethoxy styrene, hydroxy styrene, and chlorostyrene, and are preferably structural units in which R ⁵ is substituted at the p-position. . Examples of the α-methylstyrene derivative include those in which the hydrogen atom at the α-position of the vinyl group is substituted with a methyl group in the styrene derivative.

  (A) When the binder polymer contains the structural unit represented by the general formula (IV), the content is determined based on the total solid content of the (A) binder polymer, which is a copolymer, and the adhesion and solution. In terms of excellent image properties, the content is preferably 3% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 20% by mass or more. Further, in terms of excellent releasability and flexibility of the resist after curing, it is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less, 45 It is particularly preferable that the content is% by mass.

The structural unit represented by the general formula (V) is a structural unit based on (meth) acrylic acid alkyl ester. Examples of the (meth) acrylic acid alkyl ester include those in which R ⁷ is an alkyl group having 1 to 12 carbon atoms in the general formula (V). The alkyl group having 1 to 12 carbon atoms may be linear or branched, and may have a substituent such as a hydroxyl group, an epoxy group, or a halogen atom. Such (meth) acrylic acid alkyl esters include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth) ) Tert-butyl acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and structural isomers thereof Can be mentioned. From the viewpoint of improving the resolution and shortening the peeling time, R ⁷ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms having no substituent. Preferably, it is a methyl group.

  (A) When a binder polymer contains the structural unit represented by the said general formula (V), the content rate is excellent in peelability on the basis of the solid content whole quantity of the (A) binder polymer which is a copolymer. In terms of point, it is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 15% by mass or more. In terms of excellent resolution, it is preferably 55% by mass or less, more preferably 50% by mass or less, further preferably 45% by mass or less, and particularly preferably 40% by mass. preferable.

  Moreover, it is preferable that (A) binder polymer contains the structural unit further represented by the following general formula (VI) from the viewpoint of the balance of adhesiveness and resolution, and peelability.

In the general formula (VI), R ¹⁵ represents a hydrogen atom or a methyl group, R ¹⁶ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxyl group or a halogen atom, and q represents 0 to 0 5 represents an integer of 5 and when q is 2 or more, a plurality of R ¹⁶ may be the same as or different from each other.

  The structural unit represented by the general formula (VI) is a structural unit based on benzyl (meth) acrylate and benzyl (meth) acrylate derivatives. Examples of the benzyl (meth) acrylate derivative include 4-methylbenzyl (meth) acrylate, 4-ethylbenzyl (meth) acrylate, 4-tert-butylbenzyl (meth) acrylate, 4-methoxybenzyl (meth) acrylate, Examples include 4-ethoxybenzyl (meth) acrylate, 4-hydroxylbenzyl (meth) acrylate, and 4-chlorobenzyl (meth) acrylate. The structural unit represented by the general formula (VI) is based on benzyl (meth) acrylate (when q = 0) from the viewpoint of maintaining developability, etching resistance, plating resistance, and flexibility of the cured film. A structural unit is preferred.

  (A) When a binder polymer contains the structural unit represented by the said general formula (VI), the content rate is excellent in adhesiveness on the basis of the solid content whole quantity of the (A) binder polymer which is a copolymer. In terms of point, it is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. Further, in terms of excellent releasability and flexibility of the resist after curing, it is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less, 45 It is particularly preferable that the content is not more than mass%.

  These binder polymers can be used individually by 1 type or in combination of 2 or more types. Examples of combinations of binder polymers when used in combination of two or more include, for example, two or more binder polymers composed of different copolymer components (including different structural units as constituent components), two or more of different weight average molecular weights And two or more binder polymers having different dispersities. In addition, a polymer having a multimode molecular weight distribution described in JP-A No. 11-327137 may be used as a binder polymer.

  In addition, when developing with an organic solvent as a developing process described later, it is preferable to prepare a polymerizable monomer having a carboxyl group in a small amount. Moreover, the binder polymer may have a photosensitive functional group as needed.

  The blending amount of the binder polymer as the component (A) is preferably 40 to 70 parts by mass, preferably 45 to 65 parts by mass, based on 100 parts by mass of the total amount of the component (A) and the component (B) described later. More preferably, it is more preferably 50-60 parts by mass. If the blending amount is less than 40 parts by mass, the photosensitive layer cured by exposure tends to be brittle, and if it exceeds 70 parts by mass, the resolution and photosensitivity tend to be insufficient.

(Photopolymerizable compound having an ethylenically unsaturated bond)
The photopolymerizable compound having an ethylenically unsaturated bond as component (B) preferably contains a compound represented by the following general formula (II).

In the general formula (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and is preferably a methyl group. Y represents an alkylene group having 2 to 6 carbon atoms. n ¹ and n ² each independently represent a positive integer, and n ¹ + n ² is an integer of 4 to 40, preferably an integer of 6 to 34, more preferably an integer of 8 to 30. , An integer of 8 to 28 is more preferable, an integer of 8 to 20 is particularly preferable, an integer of 8 to 16 is extremely preferable, and an integer of 8 to 12 is most preferable. When the value of n ¹ + n ² is less than 4, the compatibility with the binder polymer decreases, and when the photosensitive element is laminated on the circuit forming substrate, it tends to be peeled off. When the value of n ¹ + n ² exceeds 40, The hydrophilicity of the photosensitive layer increases, the resist tends to peel off during development, and the plating resistance tends to decrease. A plurality of Y present in the molecule may be the same as or different from each other.

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

  Moreover, the aromatic ring in the said general formula (II) may have a substituent. Examples of the substituent include a halogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, a phenacyl group, an amino group, and 1 to 10 carbon atoms. Alkylamino group, dialkylamino group having 2 to 20 carbon atoms, nitro group, cyano group, carbonyl group, mercapto group, alkylmercapto group having 1 to 10 carbon atoms, allyl group, hydroxyl group, hydroxyalkyl having 1 to 20 carbon atoms Group, carboxyl group, carboxyalkyl group having 1 to 10 carbon atoms in alkyl group, acyl group having 1 to 10 carbon atoms in alkyl group, alkoxy group having 1 to 20 carbon atoms, alkoxycarbonyl group having 1 to 20 carbon atoms , An alkylcarbonyl group having 2 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an N-alkylcarbamoyl group having 2 to 10 carbon atoms, and a complex Groups containing, as well as, an aryl group substituted with these substituents include. The above substituents may form a condensed ring, and a hydrogen atom in these substituents may be substituted with the above substituent such as a halogen atom. When the number of substituents is 2 or more, the two or more substituents may be the same or different.

  Examples of the compound represented by the general formula (II) include 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acrylic). Loxypolypropoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolybutoxy) phenyl) propane and 2,2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) Examples thereof include bisphenol A-based (meth) acrylate compounds such as propane.

Specific examples of the compound represented by the general formula (II) include, for example, EO-modified bisphenol A in which R ¹ and R ² are hydrogen atoms, Y is an ethylene group, and n ¹ + n ² = 10 (average value). And diacrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-321M).

  The balance of the blending of the hydrophilic component and the hydrophobic component in the component (B) affects the resolution, adhesion, release characteristics after curing, and the like. From such a viewpoint, in order to obtain a photosensitive element excellent in resolution, adhesion, peeling property after curing, etc., it is preferable that the component (B) contains polyalkylene glycol di (meth) acrylate. As the polyalkylene glycol di (meth) acrylate, for example, a compound represented by the following general formula (VII), (VIII) or (IX) is preferable.

In general formula (VII), R ⁸ and R ⁹ each independently represent a hydrogen atom or a methyl group, EO represents an oxyethylene group, PO represents a propyleneoxy group, and s ¹ represents an integer of ¹ to 30. , R ¹ and r ² each independently represents an integer of 0 to 30, and r ¹ + r ² (average value) is an integer of 1 to 30.

In general formula (VIII), R ¹⁰ and R ¹¹ each independently represent a hydrogen atom or a methyl group. EO represents an oxyethylene group, PO represents an oxypropylene group, r ³ represents an integer of 1 to 30, s ² and s ³ each independently represents an integer of 0 to 30, and s ² + s ³ (average (Value) is an integer of 1-30.

In General Formula (IX), R ¹² and R ¹³ each independently represent a hydrogen atom or a methyl group, and is preferably a methyl group. EO represents an oxyethylene group, and PO represents an oxypropylene group. r ⁴ represents an integer of 1 to 30, and s ⁴ represents an integer of 1 to 30.

  In the general formulas (VII), (VIII) and (IX), when there are a plurality of oxyethylene group structural units (EO, oxyethylene units) and oxypropylene group structural units (PO, oxypropylene units), These oxyethylene units and oxypropylene units may be continuously present in blocks or randomly. Furthermore, when the oxypropylene unit is a structural unit of an oxyisopropylene group, the secondary carbon of the propylene group may be bonded to the oxygen atom, or the primary carbon may be bonded to the oxygen atom.

The total number of oxyethylene units (r ¹ + r ² , r ³ and r ⁴ ) in the above general formulas (VII), (VIII) and (IX) is each independently an integer of 1 to 30, but an integer of 4 or more. It is preferable that it is an integer of 5 or more. Further, in terms of excellent tent reliability and resist shape, it is preferably an integer of 10 or less, more preferably an integer of 9 or less, and still more preferably an integer of 8 or less.

The total number (s ¹ , s ² + s ³ and s ⁴ ) of the oxypropylene units in the general formulas (VII), (VIII) and (IX) are each independently an integer of 1 to 30; In terms of excellent sludge properties, it is preferably an integer of 5 or more, more preferably an integer of 8 or more, and even more preferably an integer of 10 or more. Further, in terms of excellent resolution and low sludge properties, the integer is preferably 20 or less, more preferably 16 or less, and even more preferably 14 or less.

Specific examples of the compound represented by the general formula (VII) include, for example, vinyl in which R ⁸ and R ⁹ are methyl groups, r ¹ + r ² = 6 (average value), and s ¹ = 12 (average value) A compound (trade name: FA-023M, manufactured by Hitachi Chemical Co., Ltd.).

Specific examples of the compound represented by the general formula (VIII) include, for example, vinyl in which R ¹⁰ and R ¹¹ are methyl groups, r ³ = 6 (average value), and s ² + s ³ = 12 (average value) And a compound (trade name: FA-024M, manufactured by Hitachi Chemical Co., Ltd.).

Specific examples of the compound represented by the general formula (IX) include, for example, a vinyl compound in which R ¹² and R ¹³ are hydrogen atoms, r ⁴ = 1 (average value), and s ⁴ = 9 (average value) ( Shin Nakamura Chemical Co., Ltd., NK ester HEMA-9P).

  In addition, these can be used individually by 1 type or in combination of 2 or more types.

  Moreover, as a (B) component, it is preferable that urethane monomers, such as a (meth) acrylate compound which has a urethane bond, are included in the point which is excellent in tenting property.

  Examples of the urethane monomer include (meth) acrylic monomers having a hydroxyl group at the β-position, and diisocyanate compounds such as isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 1,6-hexamethylene diisocyanate. Addition reaction product, tris ((meth) acryloxytetraethylene glycol isocyanate) hexamethylene isocyanurate, EO-modified urethane di (meth) acrylate, and EO, PO-modified urethane di (meth) acrylate. The EO-modified compound has an oxyethylene group block structure. The PO-modified compound has a block structure of oxypropylene group. Examples of the EO-modified urethane di (meth) acrylate include trade name “UA-11” manufactured by Shin-Nakamura Chemical Co., Ltd. Moreover, as EO and PO modified | denatured urethane di (meth) acrylate, Shin-Nakamura Chemical Co., Ltd. make and brand name "UA-13" are mentioned, for example. These can be used alone or in combination of two or more.

  Moreover, it is preferable that (B) component contains the compound obtained by making (alpha), (beta) -unsaturated carboxylic acid react with a polyhydric alcohol in the point which is excellent in adhesiveness, resolution, and peelability. Examples of these compounds include trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO, Examples include PO-modified trimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. Examples of the EO-modified trimethylolpropane tri (meth) acrylate include “SR-454” manufactured by Sartomer Co., Ltd. These can be used individually by 1 type or in combination of 2 or more types.

  The component (B) preferably contains a photopolymerizable compound having one ethylenically unsaturated bond in terms of excellent adhesion, resolution, and peelability. As a photopolymerizable compound having one ethylenically unsaturated bond, it is preferable to contain a compound represented by the following general formula (X).

In general formula (X), R <^14> is a hydrogen atom or a methyl group, and is preferably a hydrogen atom. Z is synonymous with Y in the general formula (II) described above, and is preferably an ethylene group. k represents an integer of 4 to 20, and from the viewpoint of developability, it is preferably an integer of 5 to 18, more preferably an integer of 6 to 12, and further preferably an integer of 6 to 10. . Moreover, the aromatic ring in the said general formula (X) may have a substituent, and the substituent similar to the aromatic ring in the general formula (II) mentioned above is mentioned as these substituents.

  Specific examples of the compound represented by the general formula (X) include, for example, nonylphenoxypolyethyleneoxy (meth) acrylate, nonylphenoxypolypropyleneoxy (meth) acrylate, butylphenoxypolyethyleneoxy (meth) acrylate and butylphenoxypolypropylene. An oxy (meth) acrylate is mentioned.

  Examples of the nonylphenoxypolyethyleneoxy (meth) acrylate include nonylphenoxytetraethyleneoxy (meth) acrylate, nonylphenoxypentaethyleneoxy (meth) acrylate, nonylphenoxyhexaethyleneoxy (meth) acrylate, nonylphenoxyheptaethyleneoxy ( (Meth) acrylate, nonylphenoxyoctaethyleneoxy (meth) acrylate, nonylphenoxynonaethyleneoxy (meth) acrylate, nonylphenoxydecaethyleneoxy (meth) acrylate, nonylphenoxyundecaethyleneoxy (meth) acrylate and nonylphenoxide decaethyleneoxy (Meth) acrylate is mentioned.

  Examples of the butylphenoxypolyethyleneoxy (meth) acrylate include butylphenoxytetraethyleneoxy (meth) acrylate, butylphenoxypentaethyleneoxy (meth) acrylate, butylphenoxyhexaethyleneoxy (meth) acrylate, butylphenoxyheptaethyleneoxy ( Examples include meth) acrylate, butylphenoxyoctaethyleneoxy (meth) acrylate, butylphenoxynonaethyleneoxy (meth) acrylate, butylphenoxydecaethyleneoxy (meth) acrylate, and butylphenoxyundecaethyleneoxy (meth) acrylate. In addition, these can be used individually by 1 type or in combination of 2 or more types.

  The component (B) may contain a photopolymerizable compound having an ethylenically unsaturated bond other than those described above. Examples of other (B) photopolymerizable compounds include compounds obtained by reacting glycidyl group-containing compounds with α, β-unsaturated carboxylic acids, phthalic acid compounds, and (meth) acrylic acid alkyl esters. .

  Examples of the phthalic acid compounds include γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate and β-hydroxyalkyl-β ′-(meth) acryloloxyalkyl-o. -Phthalates. These can be used alone or in combination of two or more.

  The blending amount of the photopolymerizable compound having an ethylenically unsaturated bond as component (B) is preferably 30 to 60 parts by mass based on 100 parts by mass of the total amount of component (A) and component (B). It is more preferably 35 to 55 parts by mass, and still more preferably 40 to 50 parts by mass. If the blending amount is less than 30 parts by mass, the resolution and photosensitivity tend to be insufficient, and if it exceeds 60 parts by mass, the photosensitive layer cured by exposure tends to become brittle.

(Photopolymerization initiator)
The photopolymerization initiator as the component (C) preferably contains a 2,4,5-triarylimidazole dimer in terms of excellent photosensitivity and adhesion. Examples of the 2,4,5-triarylimidazole dimer include 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-bromophenyl) -4,5-diphenylimidazole. Dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di (p-fluoro) Phenyl) imidazole dimer, 2- (2,6-dichlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di p-fluorophenyl) imidazole dimer, 2- (o-bromophenyl) -4,5-di (p-iodophenyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di (p -Chloronaphthyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di (p-chlorophenyl) imidazole dimer, 2- (o-bromophenyl) -4,5-di (o-chloro) -P-methoxyphenyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di (o, p-dichlorophenyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di ( o, p-dibromophenyl) imidazole dimer, 2- (o, m-dichlorophenyl) -4,5-di (p-chloronaphthyl) imidazole dimer, 2- (o, m-dichlorophenyl) -4,5-diphenylimidazole dimer, 2- (o, p-dichlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer, 2,4-di (p-methoxyphenyl) -5 -Phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer, 2- (P-bromophenyl) -4,5-diphenylimidazole dimer, 2- (o-bromophenyl) -4,5-di (o, p-dichlorophenyl) imidazole dimer, 2- (m-bromophenyl) ) -4,5-diphenylimidazole dimer, 2- (m, p-dibromophenyl) -4,5-diphenylimidazole dimer, 2,2′-bis (o-bromophe) ) -4,4 ′, 5,5′-tetra (p-chloro-p-methoxyphenyl) imidazole dimer, 2- (o-chlorophenyl) -4,5-di (o, p-dichlorophenyl) imidazole Dimer, 2- (o-chlorophenyl) -4,5-di (o, p-dibromophenyl) imidazole dimer, 2- (o-bromophenyl) -4,5-di (o, p-dichlorophenyl) ) Imidazole dimer and 2,4,5-tris (o, p-dichlorophenyl) imidazole dimer. Among these, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer is preferable from the viewpoint of further improving adhesion and photosensitivity.

  In addition, in the 2,4,5-triarylimidazole dimer, the aryl group substituents of two 2,4,5-triarylimidazoles may give the same and symmetric compounds, or differently asymmetric Such compounds may be provided.

  When the component (C) contains a 2,4,5-triarylimidazole dimer, the content ratio is preferably 70 to 100% by mass based on the total amount of the component (C), and 85 to 100 More preferably, it is 90 mass%, More preferably, it is 90-100 mass%, It is especially preferable that it is 93-100 mass%. By containing 2,4,5-triarylimidazole dimer at this ratio, the photosensitive element according to this embodiment has more excellent adhesion and photosensitivity.

  Moreover, as a photoinitiator which is (C) component, you may use another photoinitiator other than the said 2,4,5-triaryl imidazole dimer. Other photopolymerization initiators include, for example, aromatic ketones, p-aminophenyl ketones, quinones, benzoin ether compounds, benzoin compounds, benzyl derivatives, acridine derivatives, coumarin compounds, oxime esters, N-aryls. Examples include α-amino acid compounds, aliphatic polyfunctional thiol compounds, acylphosphine oxides, thioxanthones, and tertiary amine compounds, and these compounds can be used in combination.

  The (C) photopolymerization initiator according to this embodiment preferably contains the above aromatic ketones in addition to the 2,4,5-triarylimidazole dimer, and among them, N, N′-tetraethyl It is preferable to contain -4,4'-diaminobenzophenone (Michler ketone).

  The blending amount of the photopolymerization initiator (C) is preferably 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the components (A) and (B), and is 0.2 to More preferably, it is 10 mass parts, and it is especially preferable that it is 0.5-5 mass parts. If the blending amount is less than 0.1 parts by mass, the photosensitivity tends to be insufficient, and if it exceeds 20 parts by mass, the light absorption on the surface of the photosensitive resin composition increases during the exposure, and the internal There is a tendency for photocuring to be insufficient.

  In addition, the photosensitive resin composition includes, if necessary, a photopolymerizable compound (such as an oxetane compound) having a cyclic ether group capable of at least one cationic polymerization in the molecule, a cationic polymerization initiator, malachite green, and the like. Photochromic agents such as dyes, tribromophenylsulfone and leucocrystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, antifoaming agents, flame retardants, 4-t-butylcatechol, etc. Additives such as stabilizers, inhibitors, leveling agents, peeling accelerators, antioxidants, fragrances, imaging agents, and thermal crosslinking agents. These can be used alone or in combination of two or more. As long as the objective of this embodiment is not hindered, these additives may be contained in an amount of about 0.0001 to 20 parts by mass based on 100 parts by mass of the total amount of the component (A) and the 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 according to this embodiment can be formed by applying the above-described photosensitive resin composition on the support film 10 and removing the solvent. Here, as a coating method, for example, known methods such as roll coating, comma coating, gravure coating, air knife coating, die coating, and bar coating can be employed. Moreover, the removal of a solvent can be performed by processing for about 5 to 30 minutes at the temperature of 70-150 degreeC, for example. 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 a later step.

  The thickness of the photosensitive layer 20 thus formed is preferably 3 to 25 μm in thickness after drying, more preferably 5 to 25 μm, still more preferably 7 to 20 μm, It is especially preferable that it is 10-15 micrometers. If this thickness is less than 3 μm, problems tend to occur when the photosensitive layer 20 is laminated on the circuit forming substrate, and the tenting property tends to be insufficient. Further, the resist may be damaged during the development and etching processes, which may contribute to open defects, and the printed circuit board manufacturing yield tends to be reduced. On the other hand, if the thickness exceeds 25 μm, the resolution of the photosensitive layer 20 tends to be insufficient and the circumference of the etching solution tends to be insufficient. In addition, there is a possibility that the influence of side etching becomes large, and it tends to be difficult to manufacture a high-density printed wiring board.

  The photosensitive element 1 may include a protective film (not shown) on the main surface of the photosensitive layer 20 opposite to the first main surface 12 that contacts 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. It is preferable to use the film. Specific examples include inert polyolefin films such as polyethylene and polypropylene. From the viewpoint of peelability from the photosensitive layer 20, a polyethylene film is preferable. Although the thickness of a protective film changes with uses, it is preferable that it is about 1-100 micrometers.

  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 of the present embodiment may be stored, for example, as it is or in a state in which a protective film further laminated on the photosensitive layer 20 is 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. Moreover, it is preferable to install an end face separator on the end face of the photosensitive element 1 wound up in a roll shape from the viewpoint of protecting the end face, and it is preferable to install a moisture-proof end face separator from the viewpoint of edge fusion resistance. Further, as a packing method, it is preferable to wrap and package in a black sheet with low moisture permeability.

  Examples of the core material include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer).

(Method for forming resist pattern)
The resist pattern forming method of the present embodiment includes a laminating step in which the photosensitive element 1 is laminated on a circuit forming substrate in the order of the photosensitive layer 20 and the support film 10, and an actinic ray through the support film 10. This is a method including an exposure step of irradiating a predetermined portion of the photosensitive layer 20 to form a photocured portion on the photosensitive layer 20 and a developing step of removing a portion of the photosensitive layer 20 other than the photocured portion.

  In the laminating step, as a method of laminating the photosensitive layer 20 on the circuit forming substrate, when a protective film is present on the photosensitive layer 20, the photosensitive layer 20 is removed from 70 to 70 after removing the protective film. The method of laminating | stacking by crimping | bonding to a circuit formation board | substrate with the pressure of about 0.1-1 Mpa etc., heating at about 130 degreeC is mentioned. In this lamination step, lamination can also be performed under reduced pressure. The surface on which the circuit forming substrate is laminated is usually a metal surface, but is not particularly limited. Further, in order to further improve the stackability, a pre-heat treatment of the circuit forming substrate may be performed.

  Next, a photomask having a negative or positive mask pattern is aligned and brought into close contact with 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. Thereafter, in the exposure step, the photosensitive layer 20 is irradiated with an actinic ray in the form of an image via the photomask and the support film 10 to form a photocured portion on the photosensitive layer 20. As the light source of the actinic light, a known light source, for example, one that effectively emits ultraviolet light, visible light, or the like such as a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, and a xenon lamp is used. In addition, a photocuring part can also be formed in the photosensitive layer 20 using a laser direct drawing exposure method.

  Next, after the exposure step, the photomask is peeled off from the support film 10. Further, the support film 10 is peeled off from the photosensitive layer 20. Next, in the development process, the unexposed portion (unphotocured portion) of the photosensitive layer 20 is removed and developed by wet development using a developer such as an alkaline aqueous solution, an aqueous developer, an organic solvent, or dry development, and a resist pattern is developed. Can be manufactured.

  Examples of the alkaline aqueous solution include a dilute solution of 0.1 to 5 mass% sodium carbonate, a dilute solution of 0.1 to 5 mass% potassium carbonate, and a dilute solution of 0.1 to 5 mass% sodium hydroxide. The pH of the alkaline aqueous solution is preferably in the range of 9 to 11, and the temperature is adjusted according to the developability of the photosensitive layer 20. Further, a surfactant, an antifoaming agent, an organic solvent, or the like may be mixed in the alkaline aqueous solution. Examples of the development method include a dip method, a spray method, brushing, and slapping.

Moreover, as a process after a development process, you may further harden a resist pattern by performing exposure with the heating amount of about 60-250 degreeC, or the exposure amount of about 0.2-10 J / cm < ² > as needed. .

(Printed wiring board manufacturing method)
The printed wiring board manufacturing method of the present embodiment is performed by etching or plating the circuit forming substrate on which the resist pattern is formed by the resist pattern forming method. The photosensitive element according to the present embodiment is particularly suitable for the production of a printed wiring board by a method including a plating process, and is particularly suitable for use in a semi-additive construction method (SAP). As a reason suitable for use in SAP, the present inventors consider as follows. The line width of a printed wiring board produced by SAP tends to be considerably narrower than that of a printed wiring board produced by a subtractive construction method. In the case of SAP, the resist shape is transferred as it is to the plating line shape. Furthermore, in the case of a printed wiring board having an ultrafine line pattern produced by SAP, there is a tendency to reduce production yield due to the occurrence of minute resist chipping. From these requirements, the photosensitive element according to this embodiment is particularly suitable for use in SAP.

  As an etching solution used for etching, for example, a cupric chloride solution, a ferric chloride solution, and an alkaline etching solution can be used.

  Examples of 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 this strongly alkaline aqueous solution, for example, a 1 to 10% by mass sodium hydroxide aqueous solution and a 1 to 10% by mass potassium hydroxide aqueous solution are used. Moreover, as a peeling system, an immersion system and a spray system are mentioned, for example. 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.

  Further, when plating is performed on a circuit forming substrate including an insulating layer and a conductor layer formed on the insulating layer, it is necessary to remove the conductor layers other than the pattern. As this removal method, for example, a method of lightly etching after removing the resist pattern, or performing solder plating after the above plating, and then masking the wiring portion with solder by peeling off the resist pattern, and then conducting layer The method etc. which process using the etching liquid which can etch only are mentioned.

(Method for manufacturing semiconductor package substrate)
The photosensitive element 1 according to the present embodiment can also be used for a package substrate including a rigid substrate and an insulating film formed on the rigid substrate. In this case, the photocured portion of the photosensitive layer 20 may be used as an insulating film. When the photocured portion of the photosensitive layer 20 is used as, for example, a solder resist for a semiconductor package, a high-pressure mercury lamp is used for the purpose of improving solder heat resistance, chemical resistance, etc. after development in the resist pattern forming method described above. It is preferable to carry out ultraviolet irradiation or heating by means of. In the case of irradiating ultraviolet rays, the irradiation amount can be adjusted as necessary. For example, the irradiation can be performed at an irradiation amount of about 0.2 to 10 J / cm ² . Moreover, when heating a resist pattern, it is preferable to carry out for about 15 to 90 minutes in the range of about 100-170 degreeC. Furthermore, ultraviolet irradiation and heating can be performed at the same time, and after either one is performed, the other can be performed. When performing ultraviolet irradiation and heating simultaneously, it is more preferable to heat to 60 to 150 ° C. from the viewpoint of effectively imparting solder heat resistance, chemical resistance and the like.

  The solder resist formed from the photosensitive element according to the present embodiment also serves as a protective film for wiring after soldering to the substrate, and has excellent physical properties such as tensile strength and elongation, and thermal shock resistance. Therefore, it can be used as a permanent mask for a semiconductor package.

  The package substrate provided with the resist pattern in this manner is then mounted with a semiconductor element or the like (for example, wire bonding or solder connection) and then mounted on an electronic device such as a personal computer.

  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 modified in various ways without departing from the scope of the invention.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(Examples 1-9 and Comparative Examples 1-10)
A binder polymer (A) having the composition shown in Table 1 or 2 below was synthesized.

  The weight average molecular weight of the binder polymer was measured by a gel permeation chromatography (GPC) method and calculated by using a standard polystyrene calibration curve. The conditions of GPC and the acid value measurement procedure are shown below, and the measurement results are shown in Table 1 or 2.

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

(Acid value measuring method)
About 1 g of the binder polymer synthesized in an Erlenmeyer flask is weighed, dissolved by adding a mixed solvent (mass ratio: toluene / methanol = 70/30), and then an appropriate amount of a phenolphthalein solution is added as an indicator, followed by 0.1N hydroxylation. The solution was titrated with an aqueous potassium solution, and the acid value was measured from the following formula (α).
x = 10 × Vf × 56.1 / (Wp × I) (α)
In the formula (α), x represents an acid value (mgKOH / g), Vf represents a titration amount (mL) of a 0.1N KOH aqueous solution, Wp represents the mass (g) of the measured resin solution, and I Indicates the ratio (mass%) of the non-volatile content in the measured resin solution. The measurement results are shown in Tables 1 and 2.

  Each component shown in the following Table 3 was blended to prepare a photosensitive resin composition.

(Production of photosensitive element)
The PET film shown in Table 4 or 5 was prepared as a support film for the photosensitive element. Tables 4 and 5 show the results of measuring the total number and the haze of particles of 5 μm or more contained in each PET film.

The total number of particles and the like is a value obtained by measuring the number of particles of 5 μm or more existing in 1 mm ² units using a polarizing microscope. The n number (measurement number) at that time was set to 5. The haze of the support film is a value measured according to JIS K 7105. All of these support films had a thickness of 16 μm.

  Next, the solution of the photosensitive resin composition was applied on each PET film so as to have a uniform thickness. Then, the photosensitive layer was formed by drying for 2 minutes with a hot air convection dryer at 100 ° C. to remove the solvent. After drying, the photosensitive layer was covered with a protective film made of polyethylene (manufactured by Tamapoly Co., Ltd., trade name “NF-15”, thickness 20 μm) to obtain a photosensitive element. The thickness of the photosensitive layer after drying was 15 μm in all cases.

(Production of laminate)
The copper surface of a copper-clad laminate (made by Hitachi Chemical Co., Ltd., trade name “MLC-E-679”), which is a glass epoxy material in which copper foil (thickness: 35 μm) is laminated on both sides, is a MEC etch bond CZ- Surface roughening was performed using 8100 (manufactured by MEC Co., Ltd.), followed by pickling and water washing, followed by drying with an air flow. The obtained copper-clad laminate was heated to 80 ° C., and the photosensitive element was laminated so that the photosensitive layer was in contact with the copper surface while peeling off the protective film. Thus, a laminate was obtained in which the copper-clad laminate, the photosensitive layer, and the support film were laminated in this order. Lamination was performed using a 120 ° C. heat roll at a pressure of 0.4 MPa and a roll speed of 1.5 m / min. These laminates were used as test pieces in the following tests.

(Measurement of minimum development time)
The photosensitive layer laminated on the 125 mm × 200 mm square substrate was spray-developed, and the time during which the unexposed area was completely removed was measured to obtain the minimum development time. The measurement results are shown in Tables 4 and 5.

(Photosensitivity measurement test)
On the support film of the test piece, a stove 21-step tablet was placed as a negative, and an exposure machine (trade name “EXM-1201”, manufactured by Oak Manufacturing Co., Ltd.) having a high-pressure mercury lamp lamp was used to provide 100 mJ / cm. ^The photosensitive layer was exposed to an irradiation energy amount of ² . 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 the photosensitivity of the photosensitive resin composition was evaluated by measuring the number of steps of the step tablet of the photocured film formed on the copper clad laminate. The results are shown in Tables 4 and 5. The photosensitivity is indicated by the number of steps of the step tablet, and the higher the number of steps of the step tablet, the higher the photosensitivity.

(Resolution measurement test)
In order to examine the resolution, a photo tool having a stove 21-step tablet and a glass chrome type photo having a wiring pattern with a line width / space width of 2/2 to 30/30 (unit: μm) as a negative for resolution evaluation The tool is adhered to the support film of the test piece, and remaining after development of the stove 21-step step tablet using an exposure machine (trade name “EXM-1201” manufactured by Oak Manufacturing Co., Ltd.) having a high-pressure mercury lamp. The exposure was performed with an irradiation energy amount at which the step number was 5.0. Next, the support film was peeled off, and a 1% by mass aqueous sodium carbonate solution was spray-developed at 30 ° C. for 4 times the minimum development time, and development was carried out by removing unexposed portions. Here, the resolution was evaluated based on 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. Note that the smaller the numerical value, the better the evaluation of resolution. The results are shown in Tables 4 and 5.

(Evaluation of side shape of resist line)
In the substrate evaluated by the resolution measurement test, the side shape of the resist line was observed with a scanning electron microscope (trade name SU-1500, manufactured by Hitachi High-Technologies Corporation) and evaluated as follows. The results are shown in Tables 4 and 5.
A: Smooth shape B: Slightly rough shape C: Rough shape

(Adhesion measurement test)
In order to investigate the adhesion, a phototool having a 21-step stove tablet and a glass chrome type having a wiring width of 2/1000 to 30/1000 (unit: μm) as a negative for adhesion evaluation After the development of the stove 21-step tablet using an exposure machine having a high-pressure mercury lamp lamp (trade name “EXM-1201”, manufactured by Oak Manufacturing Co., Ltd.). The exposure was carried out with an irradiation energy amount such that the number of remaining step steps was 8.0. Next, the support film was peeled off, and a 1% by mass aqueous sodium carbonate solution was spray-developed at 30 ° C. for 4 times the minimum development time, and development was carried out by removing unexposed portions. Here, the adhesion was evaluated based on the smallest value (unit: μm) of the line width at which the unexposed portion could be removed cleanly by the development process. In addition, evaluation of adhesiveness is a favorable value, so that a numerical value is small. The results are shown in Tables 4 and 5.

(Test for measuring the number of resist defects)
In order to investigate the number of occurrences of resist defects, a test piece comprising a photo tool having a 21-step stove tablet and a glass chrome type photo tool having a wiring pattern with a line width / space width of 10/30 (unit: μm) Using an exposure machine having a high pressure mercury lamp lamp in close contact with the support film, exposure was performed with an irradiation energy amount that the number of remaining step stages after development of the stove 21-step step tablet was 5.0. Next, the support film was peeled off, and a 1 mass% sodium carbonate aqueous solution at 30 ° C. was sprayed for twice the minimum development time to remove unexposed portions. Next, the number of resist defects was counted using a microscope. The average value when the line length is 1 mm, the number of lines is 10 observation units, and the n number is 5, is defined as the number of resist defects. The results are shown in Tables 4 and 5.

As shown in Tables 4 and 5, the hazes of the PET films used in Examples 1-9 and Comparative Example 9 are almost the same, but are present in 1 mm ² units of the PET film used in Examples 1-9. The total number of particles such as 5 μm or more was 1, which was very small compared to the PET film used in Comparative Example 9 (the total number of particles, etc. was 28). Therefore, also in the number of occurrences of resist defects, Examples 1 to 9 have a number of occurrences of resist defects of 0, which is very small compared to Comparative Example 9. Further, when the support film having a total number of particles of 318 in Comparative Example 10 was used, the number of resist defects increased to 213. Furthermore, in Examples 1-9, the shape of the resist side surface after development was smooth, and it was confirmed that a good resist pattern was formed.

  Further, as shown in Table 4, the acid value and the weight average molecular weight of the component (A) used in Examples 1 to 9 are within an appropriate range, so the minimum development time is extremely short, and the productivity of the printed wiring board. It was confirmed that it did not decrease The range of the appropriate weight average molecular weight obtained from the above formula (I) is 1 to 53,000 when the acid value is 130 mgKOH / g, and 1 to 36,000 when the acid value is 110 mgKOH / g. When the value is 90 mg KOH / g, the value is 1 to 24,000, and when the acid value is 80 mg KOH / g, the value is 1 to 2 million.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 10 ... Support film, 12 ... 1st main surface, 14 ... 2nd main surface, 20 ... Photosensitive layer (photosensitive resin composition layer).

Claims (7)

A photosensitive element comprising a support film and a photosensitive resin composition layer formed on the support film,
The haze of the support film is 0.01 to 2.0%, and the total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more contained in the support film is 5 / mm ² or less,
The photosensitive resin composition layer contains a binder polymer, a photopolymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator,
The binder polymer is a photosensitive element having an acid value x of 60 to 130 mgKOH / g and a weight average molecular weight Mw satisfying a relationship represented by the following formula (I).
13000 ≦ Mw <4000e ^0.02x (I)
[In formula (I), x represents the acid value of the binder polymer, and Mw represents the weight average molecular weight of the binder polymer. ] The photosensitive element of Claim 1 in which the said photopolymerizable compound contains the compound represented by the following general formula (II).

[In Formula (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, Y represents an alkylene group having 2 to 6 carbon atoms, and n ¹ and n ² each independently represents a positive integer. N ¹ + n ² is 4 to 40, and a plurality of Y may be the same as or different from each other. ] The photosensitive element of Claim 1 or 2 in which the said binder polymer has a bivalent group represented by the following general formula (III), (IV) or (V).

[In the formulas (III), (IV) and (V), R ³ , R ⁴ and R ⁶ each independently represent a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 4 carbon atoms and 1 carbon atom. Represents an alkoxy group of ˜3, a hydroxyl group or a halogen atom, R ⁷ represents an alkyl group having 1 to 10 carbon atoms, p represents an integer of 0 to 5, and when p is 2 or more, a plurality of R ⁵ are present. They may be the same or different from each other. ] The photosensitive element according to claim 3, wherein the binder polymer further has a divalent group represented by the following general formula (VI).

[In the formula (VI), R ¹⁵ represents a hydrogen atom or a methyl group, R ¹⁶ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxyl group or a halogen atom, and q represents 0 to 0 5 represents an integer of 5 and when q is 2 or more, a plurality of R ¹⁶ may be the same as or different from each other. ]   The photosensitive element as described in any one of Claims 1-4 in which the said photoinitiator contains a 2,4,5-triaryl imidazole dimer. A laminating step of laminating the photosensitive element according to any one of claims 1 to 5 on the circuit forming substrate in the order of the photosensitive resin composition layer and the support film;
An exposure step of irradiating a predetermined portion of the photosensitive resin composition layer through the support film with an actinic ray to form a photocured portion in the photosensitive resin composition layer;
A developing step for removing the photosensitive resin composition layer other than the photocured portion;
A method for forming a resist pattern, comprising:   A method for manufacturing a printed wiring board, comprising a step of etching or plating a circuit forming substrate on which a resist pattern is formed by the method for forming a resist pattern according to claim 6.