JP2017003641A - Urethane (meth)acrylate and photosensitive resin composition for dry film resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for a dry film resist, which can suppress generation of aggregates in a developer and can suppress foaming.SOLUTION: A urethane (meth)acrylate represented by formula (1) is provided for a photosensitive resin composition for a dry film resist. In formula (1), Rrepresents a hydrogen atom or a methyl group; E-O represents an oxyethylene group; P-O represents an oxypropylene group; m represents an average addition molar number of oxyethylene groups; n represents an average addition molar number of oxypropylene; and m ranges from 4 to 15, n ranges from 3 to 6 and m/n ranges from 1.0 to 4.0.SELECTED DRAWING: None

Description

  The present invention relates to a urethane (meth) acrylate used for a photosensitive resin composition for dry film resist that can be patterned by photocuring and development with an aqueous alkaline solution, and a photosensitive resin composition for dry film resist.

  For electronic devices such as personal computers and mobile phones, printed wiring boards and the like are used for mounting components and semiconductors. Conventionally, a dry film resist in which a support, a photosensitive resin layer, and a protective layer are laminated is used as a resist for manufacturing a printed wiring board or the like. The photosensitive resin layer used here is generally an alkali developing type using a weak alkaline aqueous solution as a developing solution.

  After the exposure, there is a development step in which the unexposed portion of the photosensitive resin layer is dissolved or dispersed and removed in the developer, and an uneven pattern is drawn on the dry film resist. The components of the dry film resist are an alkali-soluble carboxyl group-containing polymer and a photopolymerizable compound, which are dissolved and dispersed in the developer, but the developer dispersibility is poor by repeating the development process. Insoluble components increase and aggregates (scum) are generated. When the aggregates are reattached on the substrate, pattern formation abnormalities are caused and defects such as disconnection or short-circuit are caused.

  In order to solve the problem of the generation of aggregates, urethane (meth) acrylate having an oxyalkylene group in the molecule is used as a photopolymerizable compound (Patent Documents 1 to 7). These techniques are techniques for suppressing aggregation of insoluble components in the developer by interfacial activity based on the structure of the oxyalkylene group.

JP 2008-90223 A JP 2008-139679 A JP 2008-94803 A JP 2007-128014 A JP 2008-39978 A JP 2010-277051 A JP 2011-150137 A

  However, on the other hand, the use of a surface active component causes foaming of the resin component in the developer, hindering the circulation of the developer and preventing the contact between the developer and the photosensitive resin layer, thereby removing the uncured portion. As a result, the pattern formation is abnormal. When trying to suppress foaming, the generation of aggregates cannot be stopped.

  As described above, it has become necessary to solve the conflicting problems of the generation of aggregates and the suppression of foaming of the developing solution while maintaining the basic physical properties as a dry film resist.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photosensitive resin composition for a dry film resist that can suppress the generation of aggregates in a developer and suppress foaming. is there.

  As a result of intensive studies to achieve the above-mentioned object, the photosensitive resin composition for dry film resist has a urethane (meth) acrylate and a carboxyl group having a structure in which oxyethylene groups and oxypropylene groups are connected in a block shape. The inventors have found that by using a polymer and a photopolymerization initiator as essential components, it is possible to suppress the generation of aggregates in an alkali developer and suppress foaming, and the present invention has been completed.

（Ｒ^１は、水素原子またはメチル基を表す。
Ｅ−Ｏはオキシエチレン基を表す。
Ｐ−Ｏはオキシプロピレン基を表す。
ｍは、前記オキシエチレン基の平均付加モル数を表し、ｎは、前記オキシプロピレン基の平均付加モル数を示し、ｍ＝４〜１５、ｎ＝３〜６、かつｍ／ｎ＝１．０〜４．０である。） That is, the present invention is the following [1] and [2] [1] A urethane (meth) acrylate for a photosensitive resin composition for a dry film resist, which is represented by the following general formula (1).

(R ¹ represents a hydrogen atom or a methyl group.
EO represents an oxyethylene group.
PO represents an oxypropylene group.
m represents an average addition mole number of the oxyethylene group, n represents an average addition mole number of the oxypropylene group, m = 4 to 15, n = 3 to 6, and m / n = 1.0. ~ 4.0. )

[2] A dry film resist comprising 5-75% by mass of the following component (A), 20-90% by mass of component (B) and 0.1-20% by mass of component (C). Photosensitive resin composition.

(A) The urethane (meth) acrylate (B) according to claim 1 has a weight average molecular weight of 5,000 to 500,000, and a copolymer component content of (meth) acrylic acid of 10 to 45% by mass, styrene. 5 to 55% by mass of a carboxyl group-containing polymer (C) photopolymerization initiator

  The urethane (meth) acrylate of the present invention provides a photosensitive resin composition for a dry film resist that can suppress the generation of aggregates in a developer and suppress foaming.

  In Patent Documents 1 to 7, urethane (meth) acrylate is described as a general formula. However, m and n in formula (1) are specifically disclosed in the examples when m / n = 0.11, m / n = 0.56, m / n = 0. In this case, it is only when n = 0, and there is no description or suggestion about the remarkable effect of the present invention.

The present invention is described in detail below.
<Urethane (meth) acrylate: (A) component>
The urethane (meth) acrylate of the present invention as the component (A) has a structure represented by the following general formula (1), and is used for a photosensitive resin composition for dry film resist.

  In the present invention, (meth) acrylate refers to acrylate or methacrylate. Moreover, (meth) acrylic acid also indicates acrylic acid or methacrylic acid.

（Ｒ^１は、水素原子またはメチル基を表す。
Ｅ−Ｏはオキシエチレン基を表す。
Ｐ−Ｏはオキシプロピレン基を表す。
ｍは、前記オキシエチレン基の平均付加モル数を表し、ｎは、前記オキシプロピレン基の平均付加モル数を表し、ｍ＝４〜１５、ｎ＝３〜６、かつｍ／ｎ＝１．０〜４．０である。）

(R ¹ represents a hydrogen atom or a methyl group.
EO represents an oxyethylene group.
PO represents an oxypropylene group.
m represents the average addition mole number of the oxyethylene group, n represents the average addition mole number of the oxypropylene group, m = 4 to 15, n = 3 to 6, and m / n = 1.0. ~ 4.0. )

  This urethane (meth) acrylate contains in its molecule a urethane (meth) acrylate structure which is an α, β photopolymerizable unsaturated compound based on (meth) acrylate. The compound represented by the general formula (1) requires a hydrophilic oxyethylene group from the viewpoint of imparting solubility to an alkaline developer, and suppresses the generation of aggregates in the developer by an amphiphilic structure. And an oxypropylene group from the viewpoint of controlling the foaming characteristics.

  m represents the average addition mole number of an oxyethylene group, and is 4-15. When m is smaller than 4, it does not have sufficient hydrophilicity and tends to be an aggregate in an alkali developer. From this viewpoint, m is 4 or more. On the other hand, when m is larger than 15, the hydrophilicity becomes high and the alkaline developer in which the development residue is dissolved tends to foam. From this viewpoint, m is set to 15 or less, and 13 or less is more preferable.

  n shows the average addition mole number of an oxypropylene group, is 3-6, and 3-5 are still more preferable. When n is smaller than 3, the alkali developer tends to foam, and when n is larger than 6, it tends to be an aggregate in the alkali developer.

  Further, m / n = 1.0 to 4.0 in order to achieve both the suppression of aggregates in the alkali developer and the physical property of suppressing foaming. m / n is more preferably 1.5 or more, and further preferably 3.0 or less.

  This urethane (meth) acrylate is obtained by a urethanization reaction of two molecules of a hydroxyl group-containing (meth) acrylate compound and one molecule of hexamethylene diisocyanate. The hydroxyl group-containing (meth) acrylate compound has a structure represented by the following formula (2).

R ¹ , EO, PO, m, and n are the same as those in the formula (1).
The hydroxyl group-containing (meth) acrylate compound is prepared by cationic polymerization using, for example, 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate as a substrate and using, for example, a Lewis acid catalyst disclosed in Japanese Patent Publication No. 43-9071. Thus, after ring-opening polymerization of ethylene oxide, it can be obtained by ring-opening polymerization of propylene oxide and purification using a neutralizing agent or an adsorbent.

  The reaction between the hydroxyl group-containing (meth) acrylate compound and hexamethylene diisocyanate can be carried out at a temperature range of 20 to 120 ° C. using a known and usual urethanization catalyst as necessary. As the urethanization catalyst, either a basic catalyst or an acidic catalyst can be used. Examples of the basic catalyst include amines such as pyridine, triethylamine, diethylamine and dibutylamine, and phosphines such as tributylphosphine and triphenylphosphine. Examples of the acidic catalyst include copper naphthenate, cobalt naphthenate, zinc naphthenate, metal alkoxides such as tributoxyaluminum, trititanium tetrabutoxide and zirconium tetrabutoxide, Lewis acids such as aluminum chloride, and 2-ethylhexane. Examples thereof include tin compounds such as tin, octyltin trilaurate, dibutyltin dilaurate, and octyltin diacetate. Among them, an acidic catalyst is preferably used from the viewpoint that the reaction can be accelerated by adding a small amount, and one or more of the above tin compounds are particularly preferably used. 0.005-1 mass% is preferable with respect to the total mass of a (meth) acrylate compound and hexamethylene diisocyanate, and, as for the usage-amount of a catalyst, 0.01-0.5 mass% is more preferable.

  Further, the ratio [(OH) / (NCO)] of the number of moles of hydroxyl group (OH) of the hydroxyl group-containing (meth) acrylate compound to the number of moles of isocyanate group (NCO) of hexamethylene diisocyanate is 0.90. It is preferable to be in the range of ˜1.02.

  The reaction between the hydroxyl group-containing (meth) acrylate compound and hexamethylene diisocyanate can be carried out by a method in which the (meth) acrylate compound and hexamethylene diisocyanate are charged together, a method in which the (meth) acrylate compound is dropped into hexamethylene diisocyanate, or hexamethylene. For example, a method in which diisocyanate is dropped onto a (meth) acrylate compound.

  In addition to the urethane (meth) acrylate (A), the resin composition of the present invention comprises a carboxyl group-containing polymer (B) and a photopolymerization initiator (C) described below.

<(B) component: a carboxyl group-containing polymer>
The carboxyl group-containing polymer (B) used in the present invention has a structural unit derived from (meth) acrylic acid and styrene as a copolymerizable component in the molecule from the viewpoint of solubility in an alkali developer. The carboxyl group derived from (meth) acrylic acid is necessary for imparting developability and peelability to an aqueous alkali solution to the photosensitive resin.

  The content rate as a copolymerization component of the (meth) acrylic acid in a carboxyl group-containing polymer (B) is 10-45 mass%. 20-45 mass% is preferable from a viewpoint of aggregate generation | occurrence | production in an alkali developing solution, and foaming suppression.

  From the structural unit derived from styrene, the hydrophobicity of the carboxyl group-containing polymer (B) and the physical properties as a dry film resist are derived. The content rate as a copolymerization component of styrene of a carboxyl group-containing polymer (B) is 5-55 mass%. 5-40 mass% is preferable from a viewpoint of aggregate generation | occurrence | production in an alkali developing solution, and foaming suppression.

  The weight average molecular weight of the carboxyl group-containing polymer (B) is 5,000 to 500,000. The weight average molecular weight of the carboxyl group-containing polymer (B) is 500,000 or less from the viewpoint of solubility in an alkali developer, 5000 or more from the viewpoint of the hardness of the photosensitive resin, and preferably 10,000 to 300,000. More preferably, it is 10,000 to 100,000. A weight average molecular weight is calculated | required as a weight average molecular weight (polystyrene conversion) by gel permeation chromatography (GPC), moving bed solvent: Tetrahydrofuran, and a polystyrene standard sample.

  The carboxyl group-containing polymer (B) used in the present invention can be copolymerized with at least one monomer from the following monomers in addition to (meth) acrylic acid and styrene. Examples of the monomer include a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule, such as fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester, and the like. Alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylonitrile, Aryl (meth) acrylate such as furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl (meth) acrylate, cresyl (meth) acrylate, naphthyl (meth) acrylate, etc., having a phenyl group vinyl Compounds in which an aromatic group of benzyl (meth) acrylate such as a compound (for example, styrene), methoxybenzyl (meth) acrylate or chlorobenzyl (meth) acrylate is substituted with an alkoxy group, a halogen, an alkyl group, or the like can be used. .

  The carboxyl group-containing polymer (B) is prepared by mixing (meth) acrylic acid and styrene with the above-mentioned monomer as necessary, and diluting with a solvent such as acetone, methyl ethyl ketone, or isopropanol, benzoyl peroxide, It is preferable to carry out the synthesis by adding an appropriate amount of a radical polymerization initiator such as azoisobutyronitrile and stirring with heating. In some cases, the synthesis is performed while a part of the mixture is dropped into the reaction solution. After completion of the reaction, a solvent may be further added to adjust to a desired concentration. As a synthesis means, bulk polymerization, suspension polymerization, or emulsion polymerization may be used in addition to solution polymerization.

<(C) component: photopolymerization initiator>
As the photopolymerization initiator (C) used in the present invention, a photopolymerization initiator generally known as a compound that is activated by the action of actinic rays (for example, ultraviolet rays) to initiate a polymerization reaction of a (meth) acrylic compound. If it is, it will not be specifically limited. Examples thereof include alkylphenone compounds, biimidazole compounds, triazine compounds, acylphosphine oxide compounds, and oxime compounds.

  Among these photopolymerization initiators, a polymerization initiator containing at least one selected from the group consisting of a biimidazole compound, an alkylphenone compound and an oxime compound is preferable, and in particular, a group consisting of an oxime compound and a biimidazole compound. It is more preferable that the polymerization initiator contains at least one selected from These polymerization initiators are particularly preferable because they tend to be highly sensitive.

  Examples of the oxime compound include N-benzoyloxy-1- (4-phenylsulfanylphenyl) butan-1-one-2-imine, N-ethoxycarbonyloxy-1-phenylpropane-1-one-2-imine, N-benzoyloxy-1- (4-phenylsulfanylphenyl) octane-1-one-2-imine, N-acetoxy-1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3- Yl] ethane-1-imine, N-acetoxy-1- [9-ethyl-6- {2-methyl-4- (3,3-dimethyl-2,4-dioxacyclopentanylmethyloxy) benzoyl}- 9H-carbazol-3-yl] ethane-1-imine and the like.

  Examples of the biimidazole compound include 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2, 3-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole (see, for example, JP-A-6-75372 and JP-A-6-75373), 2,2′-bis (2- Chlorophenyl) -4,4 ′, 5,5′-tetra (alkoxyphenyl) biimidazole, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetra (dialkoxyphenyl) bi Imidazole, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetra (trialkoxyphenyl) biimidazole (for example, JP-B-48-38403, JP-A-62-1) Referring 4204 JP, etc.), 4,4 ', phenyl 5,5'-position imidazole compound substituted by carbalkoxy group (for example, see Publication No. Hei 7-10913) and the like. Preferably, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2,3-dichlorophenyl) -4 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (2,4-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole.

  Further, as a photopolymerization initiator, benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4 ′ -Benzophenone compounds such as methyldiphenyl sulfide, 3,3 ', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone; 9,10-phenanthrenequinone, 2- Examples include quinone compounds such as ethyl anthraquinone and camphor quinone; 10-butyl-2-chloroacridone, benzyl, methyl phenylglyoxylate, and titanocene compounds.

<Photosensitive resin composition for dry film resist>
The blending of the photosensitive resin composition for dry film resist of the present invention will be described below.

  The ratio of the urethane (meth) acrylate (A) used in the present invention is 100% by mass of the total amount of the component (A), the component (B) and the component (C) of the photosensitive resin composition for dry film resist. When it is in the range of 5 to 75% by mass. If the urethane (meth) acrylate (A) is less than 5% by mass, the sensitivity is insufficient, and the cured product has insufficient hardness, so that a normal pattern is not formed during development. From this viewpoint, the proportion of the component (A) is 5% by mass or more, and more preferably 15% by mass or more. Further, when the proportion of the component (A) exceeds 75% by mass, the photosensitive resin layer becomes too soft, and the dry film resist having a three-layer structure of the support, the photosensitive resin layer, and the protective layer is stored in the form of a roll. When this occurs, a phenomenon that the photosensitive resin layer protrudes occurs. From this viewpoint, the ratio of the component (A) is 75% by mass or less, and more preferably 60% by mass or less.

  The ratio of the carboxyl group-containing polymer (B) used in the present invention is in the range of 20 to 90% by mass when the total amount of the component (A), the component (B) and the component (C) is 100% by mass. . When the proportion of the carboxyl group-containing polymer (B) is less than 20% by mass, the cured product tends to be brittle. From this viewpoint, the proportion of the carboxyl group-containing polymer (B) is set to 20% by mass or more, and more preferably 40% by mass or more. Moreover, when the ratio of a carboxyl group-containing polymer (B) exceeds 90 mass%, photosensitivity will become inadequate. In this respect, the proportion of the carboxyl group-containing polymer (B) is 90% by mass or less, and more preferably 70% by mass or less.

  The ratio of the photopolymerization initiator (C) used in the present invention is when the total amount of the component (A), the component (B) and the component (C) of the photosensitive resin composition for dry film resist is 100% by mass. The range is 0.1 to 20% by mass. From the viewpoint of photosensitivity, the ratio of the photopolymerization initiator (C) is preferably 0.1% by mass or more, and more preferably 1.0% by mass or more. Moreover, when the ratio of a photoinitiator exceeds 20 mass%, the light absorption in the surface layer part of the photosensitive resin layer will increase, and photocuring of a bottom part will become inadequate. From this viewpoint, the ratio of the photopolymerization initiator (C) is set to 20% by mass or less, and more preferably 10% by mass or less.

  Each component including the above components (A), (B), and (C) may be blended together, or may be blended sequentially after each component is dissolved in a solvent. In addition, there are no particular restrictions on the charging order and working conditions when blending. For example, a resin composition may be prepared by dissolving all components in a solvent at the same time, and if necessary, each component is appropriately made into two or more solutions, and these solutions are used at the time of use (at the time of application). May be mixed to prepare a resin composition.

  In addition to the components described above, coloring materials such as dyes and pigments may be added to the photosensitive resin composition for dry film resists of the present invention. Examples of such coloring substances include phthalocyanine green, crystal violet, methyl orange, Nile blue 2B, Victoria blue, malachite green, basic blue 20, and diamond green.

  Moreover, you may add a color former to the photosensitive resin composition for dry film resists of this invention so that a visible image can be given by exposure. Examples of such coloring dyes include leuco dyes or combinations of fluoran dyes and halogen compounds. Examples of the halogen compound include amyl bromide, isoamyl bromide, isobutylene bromide, ethylene bromide, diphenylmethyl bromide, benzal bromide, methylene bromide, tribromomethylphenyl sulfone, carbon tetrabromide, tris (2, 3-dibromopropyl) phosphate, trichloroacetamide, amyl iodide, isobutyl iodide, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, hexachloroethane, and chlorinated triazine compounds. .

  Furthermore, for the purpose of improving the thermal stability and storage stability of the photosensitive resin composition for dry film resists of the present invention, a radical polymerization inhibitor may be added to the photosensitive resin composition for dry film resists.

  The photosensitive resin composition for dry film resist of the present invention may be a photosensitive resin composition solution for dry film resist to which a solvent is added. Suitable solvents include ketone solvents typified by methyl ethyl ketone, and alcohols typified by methanol, ethanol, isopropanol and the like. It is preferable to add a solvent so that the viscosity of the photosensitive resin composition solution for a dry film resist is 500 to 4000 mPa · sec at 25 ° C.

  The photosensitive resin composition for a dry film resist of the present invention forms a photosensitive resin composition layer for a dry film resist formed by coating and drying the photosensitive resin composition for a dry film resist of the present invention on a support. If necessary, a laminate having a protective layer on the surface opposite to the support of the photosensitive resin layer can be used as a dry film resist. The support used here is preferably a transparent one that transmits light from the exposure light source. For example, a polyethylene terephthalate film, a polyvinyl alcohol film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyvinylidene chloride film, a chloride chloride, and the like. Examples include vinylidene copolymer film, polymethyl methacrylate copolymer film, polystyrene film, polyacrylonitrile film, styrene copolymer film, polyamide film, and cellulose derivative film. These films can be stretched if necessary. The haze is preferably 5 or less. A thinner film is preferable from the viewpoints of image forming properties and economic efficiency, but a film having a thickness of 10 to 30 μm is preferably used because of the need to maintain the strength.

  For the protective layer, a polyethylene film or a polypropylene film can be preferably used. The thickness of the protective layer is preferably 10 to 100 μm, more preferably 10 to 50 μm.

  The thickness of the laminate using the photosensitive resin composition for dry film resists of the present invention is preferably 5 to 100 μm, more preferably 7 to 60 μm. As the thickness is thinner, the resolution is improved, and as the thickness is thicker, the film strength is increased. Therefore, the thickness can be appropriately selected according to the application.

  A conventionally known method can be adopted as a method of forming a laminate of a photosensitive resin composition for a dry film resist by sequentially laminating a support, a photosensitive resin layer, and a protective layer as necessary. . For example, the photosensitive resin composition for dry film resist used for the photosensitive resin layer is prepared in the above-described photosensitive resin composition solution for dry film resist, and applied on the support using a bar coater or a roll coater. Then, a photosensitive resin layer made of the photosensitive resin composition for dry film resist is laminated on the support. Next, a photosensitive resin laminate can be formed by laminating a protective layer on the photosensitive resin layer as necessary.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Synthesis Example 1)
In a four-necked flask equipped with a stirrer, an air introduction tube, and a thermometer, polyoxyethylene polyoxypropylene monomethacrylate (oxyethylene group repeating unit number = 12, oxypropylene group repeating unit number = 5, hydroxyl value = 65 mg KOH / g; measured value, block addition) 456 parts, hexamethylene diisocyanate (Duranate HDI-50M, manufactured by Asahi Kasei Chemicals Corporation, NCO content 50% (mass%)) 44 parts, dibutyltin dilaurate (hereinafter referred to as “DBTDL”) .) 0.01 part and 0.01 part of hydroquinone monomethyl ether (hereinafter referred to as “MEHQ”) were added. At this time, the equivalent ratio of isocyanate group / hydroxyl group is 1.0.

  Next, after reacting for 5 hours while maintaining the internal temperature at 60 ° C. while blowing air, the isocyanate group content becomes 0.05% or less by the method of JIS K 1603-1, and the isocyanate groups are almost all hydroxyl groups. After confirming that a urethane bond was formed by reaction, 500 parts of urethane acrylate (a-1) was obtained.

The obtained urethane (meth) acrylate (a-1) is a compound in which R ¹ is a methyl group, m is 12, and n is 5 in the general formula (1). The viscosity at 25 ° C. was 1250 mPa · s.

(Synthesis Examples 2 and 3)
Urethane (meth) acrylate (a-2) used in the present invention in the same manner as in Synthesis Example 1 except that polyoxyethylene polyoxypropylene monomethacrylate having different chain lengths of EO and PO and the blending amount of the components were changed. Synthesis of a-3) was performed. The blending amounts are shown in Table 1 together with the synthesis results.

(Comparative Synthesis Examples 1 to 3)
A urethane (meth) acrylate (a ′ different from that used in the present invention, in the same manner as in Synthesis Example 1 except that polyoxyethylene polyoxypropylene monomethacrylate having different chain lengths of EO and PO and the amount of the components were changed. -1) to (a′-3) were synthesized. The blending amounts are shown in Table 1 together with the synthesis results.

  Table 2 shows the composition of the photosensitive resin composition for dry film resist using the urethane (meth) acrylate of Table 1.

The details of the materials used in the table are as follows.
Carboxyl group-containing polymer (B)
(B-1):
Methacrylic acid / methyl methacrylate / styrene = 40/50/10 (mass ratio), weight average molecular weight = 50,000
(B-2):
Methacrylic acid / methyl methacrylate / styrene = 30/40/30 (mass ratio), weight average molecular weight = 80,000
Photopolymerization initiator (C)
(C-1):
2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole

<Combination liquid by alkaline developer and photosensitive resin composition for dry film resist>
1% sodium carbonate aqueous solution / photosensitive resin composition for dry film resist = 400/1 (wt) was prepared.
<Bubbling evaluation>
Fill the 50 mL screw tube with 40 mL of the compounded liquid adjusted to 30 ° C., cover and shake it up and down at a speed of 100 times / 30 seconds until bubbles generated completely disappear immediately after the end of the shaking. Was measured. The shorter the time until the generated bubbles disappear, the lower the foaming property. The case where bubbles disappeared within 30 seconds was evaluated as ◎, the case where bubbles disappeared within 60 seconds was evaluated as ○, and the case where bubbles exceeded 60 seconds was evaluated as ×.

<Dispersibility evaluation>
Fill the 50 mL screw tube with 40 mL of the compounded liquid adjusted to 30 ° C., cover and shake it up and down at a speed of 100 times / 30 seconds, and leave it for 30 minutes after shaking. It was confirmed visually. The smaller the amount of the precipitate, the better the dispersibility. The case where no precipitate was observed was evaluated as ◎, the case where a precipitate was slightly observed was evaluated as ◯, and the case where a large amount of precipitate was observed was evaluated as ×.

  In Examples 1 to 4, it was found that by using the photosensitive resin composition for dry film resist of the present invention, generation of aggregates in the developer was suppressed, and foaming was low.

In Comparative Example 1, n is outside the scope of the present invention, and foaming is high.
In Comparative Example 2, m and n are out of range and m / n is out of range, foaming occurs, and dispersibility is poor.
In Comparative Example 3, n is out of range and m / n is out of range, foaming occurs, and dispersibility is poor.

<Evaluation as photosensitive resin composition for dry film resist>
A photosensitive resin layer having a thickness of 40 μm using a bar coater on a polyethylene terephthalate film having a thickness of 20 μm using the photosensitive resin composition for dry film resist mixed with the colorant leuco crystal violet in Examples 1 to 4. Was made. After laminating the laminate with a laminator on a copper clad laminate, the line and space pattern with a line and space width of 1: 1 was used as a pattern mask, and the exposure amount was 50 mJ / cm ² using an ultra high pressure mercury lamp. And exposed. After peeling off the polyethylene terephthalate film, a 1% by mass aqueous sodium carbonate solution at 30 ° C. was sprayed for a predetermined time to dissolve and remove the unexposed portion of the photosensitive resin layer. As a result, the adhesion to the copper clad laminate after development and the cured resist line were normally formed, and a dry film resist as designed could be obtained.

The dry film resist using the photosensitive resin composition for dry film resist of the present invention can suppress the generation of agglomerates in the developer during development and suppress foaming, so that an alkali development type printed wiring board, It is useful as a dry film resist for producing lead frames and semiconductor package substrates.

Claims (2)

A urethane (meth) acrylate for a photosensitive resin composition for a dry film resist, which is represented by the following general formula (1).

(R ¹ represents a hydrogen atom or a methyl group.
EO represents an oxyethylene group.
PO represents an oxypropylene group.
m represents an average addition mole number of the oxyethylene group, n represents an average addition mole number of the oxypropylene group, m = 4 to 15, n = 3 to 6, and m / n = 1.0. ~ 4.0. )
5 to 75% by mass of the following component (A), 20 to 90% by mass of component (B), and 0.1 to 20% by mass of component (C), which are photosensitive for dry film resists Resin composition.

(A) The urethane (meth) acrylate (B) according to claim 1 has a weight average molecular weight of 5,000 to 500,000, and a copolymer component content of (meth) acrylic acid of 10 to 45% by mass, styrene. 5 to 55% by mass of a carboxyl group-containing polymer (C) photopolymerization initiator