JP2009091458A - Resin composition, photosensitive film using it, method for forming resist pattern, and printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphorus-containing compound capable of securing sufficient flame retardance without using a halogen-based flame retardant, obtaining a sufficient resolution by alkaline developing liquid, without having the discoloration of surface and blisters at the boundary of copper and a resin on a wiring board in the PCT test, and also sufficiently reducing the problem of bleeding out, a resin composition containing the phosphorus-containing compound, a photosensitive film using the resin composition, a method for forming a resist pattern and a printed wiring board. <P>SOLUTION: This phosphorus-containing compound contains a resin having a repetition unit expressed by a specific chemical formula, (B) a photopolymerizable compound having an ethylene non-saturated group, and (C) a resin compound containing a polymer initiator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phosphorus-containing compound, a resin composition containing the phosphorus-containing compound, a photosensitive film using the resin composition, a method for forming a resist pattern, and a printed wiring board.

  The demand for electronic devices and electronic components is increasing in terms of non-pollution, low toxicity, and safety, as well as global environmental issues and increasing interest in human safety. Among them, reduction of harmful gases when electronic devices and electronic components are incinerated is being demanded. In particular, it is said that the halogen-based flame retardants used so far may generate dioxins and the like when burned. In response to this, development of non-halogen flame retardants is strongly demanded. In the field of printed wiring boards used for these electronic devices and electronic components, halogen-based flame retardants have been used for circuit-forming boards such as copper-clad laminates, insulating resins, solder resists, and the like. Conventionally, most of the halogen compounds used as flame retardants are bromine-based, and brominated epoxy resins such as tetrabromobisphenol A are widely used.

  As a brominated epoxy resin, for example, an acid pendant brominated epoxy acrylate is known (see, for example, Patent Document 1). In an example in which this is used as a flame retardant for a solder resist, it is used at a high temperature for a long time. In this case, the halide may be dissociated to cause wiring corrosion. From the viewpoint of avoiding the occurrence of defects due to such dissociation of halides, there is an urgent need to develop a printed wiring board material that does not contain a halogen compound. Therefore, the use of inorganic compounds such as nitrogen compounds, phosphorus compounds, aluminum hydroxide, and magnesium hydroxide has been proposed as non-halogen flame retardants for imparting flame retardancy to resin compositions. Among these, in particular, phosphorus flame retardants have been extensively studied, and many uses of aromatic phosphates have been proposed (see, for example, Patent Documents 2 to 4).

  On the other hand, with the downsizing, weight reduction, and multi-functionalization of electronic devices and electronic components, the photosensitive resin (photosensitive material) such as dry film for circuit formation and solder resist has increased in density on the printed wiring board. There is a demand for higher resolution to cope with the above. In consideration of environmental problems, an alkali development type using a dilute alkaline aqueous solution as a developing solution has become mainstream.

  Formation of a resist pattern using a photosensitive material is performed by developing and image-forming a resin composition as a raw material after exposure. In such a process, the resin composition is photocured by exposure, but in order to obtain high resolution by development using an alkaline developer, the photocuring degree of the exposed area is increased and the solubility of the unexposed area is increased. That is, it is required to increase the contrast between the exposed portion and the unexposed portion. In order to increase the solubility of the unexposed area, there is a method of introducing a hydrophilic group into the photosensitive resin composition. When a carboxyl group is applied as such a hydrophilic group, the degree of hydrophilicity is represented by an acid value, and the higher the acid value resin, the higher the solubility.

  However, in the case of a permanent resist such as a solder resist, the higher the acid value polymer, the higher the water absorption rate. Therefore, insulation resistance and heat resistance under high temperature and high humidity, that is, high temperature and humidity resistance are likely to decrease. . Therefore, in order to ensure high temperature and humidity resistance, a liquid solder resist ink composition using a reaction product of a novolak type epoxy compound and an unsaturated carboxylic acid as an active energy ray curable resin has been developed (for example, Patent Document 5). reference). Further, the phosphates of Patent Documents 2 to 4 have a problem in water resistance because the ester bond is easily hydrolyzed. In the field of permanent resists, as a water resistance evaluation, a PCT (abbreviation of “pressure cooker test”) test for evaluating high temperature moisture resistance is performed. In this method, after the resist formed on the wiring board is placed under high temperature and high humidity for a certain time, the discoloration of the resist and the degree of swelling at the interface between the copper and the resist on the wiring board are evaluated.

  By the way, since a solder resist easily reacts with an epoxy resin, the product is often sold in two parts (two-part type of an epoxy group-containing solution and a carboxyl group-containing solution). However, since the pot life when mixing two liquids is as short as several hours to one day, the usage conditions are limited, or when two liquids are mixed in advance to form a film, it is difficult to store them in a film state. It was. As a one-component resin composition in which such problems are unlikely to occur, a photo-curing resin obtained by reacting a reaction product of a novolak epoxy compound and an unsaturated monobasic acid with an alicyclic dibasic acid anhydride A one-component liquid photo solder resist ink composition comprising a photopolymerization initiator, a diluent, and a thermosetting accelerator such as a vinyl triazine compound is known (for example, see Patent Document 6).

  Non-halogen flame retardants as described above include filler-type flame retardants that are insoluble in solvents and flame retardants that are soluble in solvents and can be mixed with other resin components. However, with the former flame-retardant that is insoluble in the solvent, when the B-stage film state is used as the insulating material, the flexibility is lowered and the handling is hindered. As a result, cracks are likely to occur, and the reliability of electronic parts using the cracks is problematic.

  In addition, since a non-halogen flame retardant needs to be added in a large amount in order to impart sufficient flame retardancy, particularly when the former flame retardant is used in the resin composition, the resin composition in the unexposed area. In some cases, the solubility in the alkaline developer is lowered, and the resolution is lowered. In the latter solvent-soluble flame retardants, low molecular weight aromatic phosphates are typical examples, but when added to a resin composition, the molecular weight is small and the volatility is high. There is a problem that it is easy to out.

  Moreover, the printed wiring board produced using the ink composition of Patent Document 5 has a problem that swelling at the interface between copper and resist on the wiring board occurs under high temperature and high humidity. This problem is caused by insufficient adhesion at the interface between copper and resist on the wiring board, gasification of low molecular weight compounds decomposed in the resist under high temperature and high humidity, stress generated by photocuring reaction or thermosetting reaction This is considered to be due to the release under high humidity. The thermosetting reaction here is a ring-opening reaction between an epoxy compound and an unsaturated carboxylic acid. Further, the ink composition of Patent Document 6 also has a problem that blistering occurs at the interface between copper and resin on the wiring board in the PCT test. This is also the same as described above, but the thermosetting reaction is due to the thermosetting agent.

Japanese Patent Laid-Open No. 11-181050 JP-A-48-90348 JP 59-45351 Japanese Patent Laid-Open No. 5-70671 JP-A 61-243869 JP-A-4-281454

  The present invention has been made in view of the above-mentioned problems of the prior art, and can ensure sufficient flame retardancy without using a halogen-based flame retardant, and sufficient resolution can be obtained with an alkali developer. A phosphorus-containing compound that does not cause discoloration of the surface in the PCT test and does not bulge at the interface between copper and the resin on the wiring board, and has sufficiently reduced the problem of bleed-out. An object of the present invention is to provide a resin composition, a photosensitive film using the resin composition, a method for forming a resist pattern, and a printed wiring board.

The present invention relates to the following.
1. (A) a resin having a repeating unit represented by the following general formulas (1), (2) and (3), (B) a photopolymerizable compound having an ethylenically unsaturated group, and (C) a polymerization initiator Resin composition.

［式（１）中、Ｘは単結合又は２価の有機基を示し、Ｒ^１及びＲ^２は各々独立に、水酸基、炭素数１〜６の脂肪族炭化水素基、炭素数１〜３のアルキルオキシ基、アリール基又はアリールオキシ基を示し、Ｒ^３は水素原子又はメチル基を示す。式（２）中、Ｒ^４は水素原子又はメチル基を示す。式（３）中、Ｙは単結合又は炭素数１〜６の脂肪族炭化水素基、下記一般式（４）で表される有機基を示し、Ｒ^５は各々独立に水素原子又はメチル基を示し、Ｒ^６は炭素数１〜２０の脂肪族炭化水素基、フェニル基、ベンジル基又は下記一般式（５）で表される有機基を示し、ｎは１〜５の整数を示す。］

[In the formula (1), X represents a single bond or a divalent organic group, and R ¹ and R ² each independently represent a hydroxyl group, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, or an alkyl group having 1 to 3 carbon atoms. An alkyloxy group, an aryl group or an aryloxy group; and R ³ represents a hydrogen atom or a methyl group. In formula (2), R ⁴ represents a hydrogen atom or a methyl group. In formula (3), Y represents a single bond or an aliphatic hydrocarbon group having 1 to 6 carbon atoms and an organic group represented by the following general formula (4), and R ⁵ each independently represents a hydrogen atom or a methyl group. R ⁶ represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms, a phenyl group, a benzyl group, or an organic group represented by the following general formula (5), and n represents an integer of 1 to 5. ]

［式（４）中、ｌは０〜２０の整数を示し、ｍは０〜２０の整数を示し、ｌ及びｍのどちらか一方は１以上である。］

[In Formula (4), l shows the integer of 0-20, m shows the integer of 0-20, and either one of l and m is 1 or more. ]

［式（５）中、Ｒ^７は炭素数１〜２０の脂肪族炭化水素基、ハロゲン原子、ヒドロキシ基、アミノ基、シアノ基又は炭素数１〜５のアルコキシ基を示し、ｐは１〜５の整数を示す。］

[In Formula (5), R ⁷ represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a hydroxy group, an amino group, a cyano group, or an alkoxy group having 1 to 5 carbon atoms, and p is 1 to 5 Indicates an integer. ]

2. Item 2. The resin composition according to item 1, which is a resin having a repeating unit represented by the following general formula (6) in addition to the repeating unit represented by the general formulas (1), (2) and (3).

［式（６）中、Ｒ^８は水素原子又はメチル基を示し、Ｒ^９は炭素数１〜２０の脂肪族炭化水素基を示す。］

Wherein (6), ^{R 8} represents a hydrogen atom or a methyl group, ^{R 9} represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms. ]

3. Item 3. The resin composition according to Item 1 or 2, wherein X in the general formula (1) is any one of the following general formulas (7) to (11).

［式（７）中、ａは１〜１０の整数を示す。］

[In Formula (7), a shows the integer of 1-10. ]

［式（８）中、Ｌ^１は炭素数１〜３のアルキレン基を示す。］

Wherein (8), ^{L 1} represents an alkylene group having 1 to 3 carbon atoms. ]

［式（９）中、Ｌ^２は炭素数１〜３のアルキレン基を示す。］

Wherein (9), ^{L 2} represents an alkylene group having 1 to 3 carbon atoms. ]

［式（１０）中、ｂは１〜１０の整数を示す。］

[In formula (10), b shows the integer of 1-10. ]

［式（１１）中、ｃは１〜１０の整数を示す。］

[In formula (11), c represents an integer of 1 to 10. ]

4). A photosensitive film comprising a support and a resin composition layer comprising the resin composition according to any one of Items 1 to 3 formed on the support.
5). Item 4. The resin composition according to any one of Items 1 to 3, which covers the conductive layer on the insulating substrate of a laminated substrate including a conductive layer having a circuit pattern formed on the insulating substrate and the circuit pattern. A resist comprising: forming a resin composition layer; irradiating a predetermined portion of the resin composition layer with actinic rays to form an exposed portion; and removing a portion other than the exposed portion of the resin composition layer Pattern formation method.
6). A printed wiring board comprising an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a resist layer formed on the insulating substrate so as to cover the conductor layer, wherein the resist layer is A printed wiring board comprising a cured product of the resin composition according to any one of 1 to 3, and having an opening so that a part of the conductor layer is exposed.

  According to the present invention, sufficient flame retardancy can be ensured without using a halogen-based flame retardant, sufficient resolution can be obtained with an alkaline developer, and is often found in low molecular weight aromatic phosphates. Phosphorus-containing compound that can sufficiently reduce the problem of bleed-out during heating caused by high volatility and has sufficient PCT resistance, and resin composition containing this phosphorus-containing compound A photosensitive film, a resist pattern forming method, and a printed wiring board using the product and the resin composition can be provided.

  According to the resin composition of the present invention, by adopting the configuration as described above, sufficient flame retardancy can be ensured without using a halogen-based flame retardant, and sufficient resolution can be obtained with an alkali developer. Thus, the problem of bleeding out is sufficiently reduced, and a cured product free from discoloration of the surface in the PCT test and blistering at the interface between the copper and the resin on the wiring board can be obtained.

  Here, the present inventors infer the reason why the above-described effect can be obtained from the resin composition of the present invention as follows. That is, the phosphorus-containing compound of the present invention can exhibit sufficient flame retardancy by having the structural unit represented by the general formula (1) having a side chain having a structure containing phosphorus. it is conceivable that.

  Further, by using a resin having a repeating unit represented by the above general formulas (1), (2) and (3), it is excellent in compatibility with a photopolymerizable compound having an ethylenically unsaturated group, and acetone. Decrease in handleability in the B-stage film state, which has a high solubility in solvents such as methyl ethyl ketone, N, N-dimethylformamide, etc. Can be sufficiently suppressed.

  In addition, the phosphorus-containing compound has a sufficiently high molecular weight Mw (for example, 1,000 or more), so that it is caused by high volatility often found in monomers and low molecular weight aromatic phosphates. The occurrence of bleed out is considered to be sufficiently suppressed.

  Furthermore, since the resin composition of the present application is a copolymer containing a carboxyl group, the solubility in an alkaline developer is sufficiently high. Therefore, it is considered that the resin composition of the present application has high resolution in the alkali developer in the unexposed area, and thus the resolution is improved. In this case, the high hydrophilicity can be determined using the acid value as an index. The higher the acid value of the compound, the higher the solubility in an alkali developer.

  In addition, since the resin having the repeating unit represented by the general formulas (1), (2) and (3) includes the structural unit represented by the general formula (3), the acid value can be adjusted by the hydrophobic portion. Further, it becomes possible to improve the moisture resistance by this hydrophobic portion, and it is considered that the discoloration of the surface in the PCT test and the swelling at the interface between the copper and the resin on the wiring board can be suppressed.

  Moreover, in the structural unit represented by the general formula (1), the more phosphate ester bonds, the lower the hydrolysis resistance, and the tendency is particularly high in phosphates having three ester bonds. Therefore, it is preferable that the structural unit represented by the general formula (1) does not include a phosphate ester bond. Thereby, hydrolysis resistance improves and it can suppress the discoloration of the surface in a PCT test, and the blistering of the interface of the copper and resin on a wiring board.

  According to the resin composition of the present invention, by including the phosphorus-containing resin that is the structural unit represented by the general formula (1) having the above-described structure, sufficient flame retardancy can be achieved without using a halogen-based flame retardant. Can be ensured, sufficient resolution can be obtained with an alkali developer, bleeding problems can be sufficiently reduced, surface discoloration in the PCT test and at the interface between copper and resin on the wiring board. Can suppress blistering.

  When the resin composition according to the present invention is used for a photosensitive permanent resist, it has a structural unit represented by the general formula (2) in the resin and is therefore soluble in an alkali developer. It is possible to cure only a desired portion by exposure by light irradiation, and then easily remove the resin of the unexposed portion with a developer.

  Furthermore, in the case of filler-type flame retardants that are insoluble in the solvent, light wraparound occurs due to light scattering caused by the flame retardants at the boundary between the exposed part and the unexposed part. According to the resin composition of the invention, since the compatibility between the phosphorus-containing compound as a flame retardant and the other resin is good, high resolution can be expected.

  The present invention also has sufficient flame retardancy without using a halogen-based flame retardant by including a support and a resin composition layer comprising the resin composition according to the present invention formed on the support. It is possible to ensure a sufficient resolution with an alkali developer, and it is possible to form a resist (permanent resist) having sufficient PCT resistance.

  The present invention also comprises the resin composition of the present invention so as to cover the conductor layer on the insulating substrate of the laminated substrate including the insulating substrate and a conductor layer having a circuit pattern formed on the insulating substrate. A resin composition layer is formed, an exposed portion is formed by irradiating a predetermined portion of the resin composition layer with actinic rays, and a resist pattern is formed by removing portions other than the exposed portion of the resin composition layer Therefore, sufficient flame retardancy can be ensured without using a halogen-based flame retardant, sufficient resolution can be obtained with an alkali developer, and a resist pattern having sufficient PCT resistance can be formed. Can do. Here, the resin composition layer composed of the resin composition of the present invention may be one obtained by laminating the resin composition layer of the photosensitive film on an insulating substrate using the photosensitive film of the present invention. Good.

  The present invention further includes a printed wiring board comprising an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a resist layer formed on the insulating substrate so as to cover the conductor layer. The resist layer is made of a cured product of the resin composition according to the present invention, and a printed wiring board such as a resist layer is formed by having an opening so that a part of the conductor layer is exposed. Since the cured product is obtained by curing the resin composition of the present invention, the cured product can ensure sufficient flame retardancy without using a halogen-based flame retardant, and an alkaline developer is sufficient. A printed wiring board having high resolution and sufficient PCT resistance can be realized.

Hereinafter, the best mode for carrying out the invention will be described in detail with reference to the drawings as the case may be. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
(A) Resin The resin composition of the present invention has a repeating unit represented by the general formulas (1), (2) and (3). Such a resin can be synthesized by a conventional radical polymerization or the like from monomers of the respective structural units of the general formulas (1), (2) and (3).
As a monomer of the structural unit represented by the general formula (1), for example, 2-acryloyloxyethyl phosphate (manufactured by Shin Nippon Chemical Co., Ltd., trade name: Z-100), diphenyl- (2-methacryloyloxyethyl) Phosphate (manufactured by Daihachi Chemical Industry Co., Ltd., trade name: MR-260), 2-methacryloyloxyethyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd., trade name: MR-200), diphenyl- (methacryloyloxymethyl) phosphonate, Diphenyl- (2- (methacryloyloxy) ethyl) phosphonate, diphenyl- (3- (methacryloyloxy) propyl) phosphonate, diphenyl- (4- (methacryloyloxy) butyl) phosphonate, diphenyl- (5- (methacryloyloxy) pentyl) Phosphonate, gif Nyl- (6- (methacryloyloxy) hexyl) phosphonate, dimethyl- (methacryloyloxymethyl) phosphonate, dimethyl- (2- (methacryloyloxy) ethyl) phosphonate, dimethyl- (3- (methacryloyloxy) propyl) phosphonate, dimethyl- (4- (methacryloyloxy) butyl) phosphonate, dimethyl- (5- (methacryloyloxy) pentyl) phosphonate, dimethyl- (6- (methacryloyloxy) hexyl) phosphonate, diethyl- (methacryloyloxymethyl) phosphonate, diethyl- (2 -(Methacryloyloxy) ethyl) phosphonate, diethyl- (3- (methacryloyloxy) propyl) phosphonate, diethyl- (4- (methacryloyloxy) butyl) phospho , Diethyl- (5- (methacryloyloxy) pentyl) phosphonate, diethyl- (6- (methacryloyloxy) hexyl) phosphonate, dipropyl- (methacryloyloxymethyl) phosphonate, dipropyl- (2- (methacryloyloxy) ethyl) phosphonate , Dipropyl- (3- (methacryloyloxy) propyl) phosphonate, dipropyl- (4- (methacryloyloxy) butyl) phosphonate, dipropyl- (5- (methacryloyloxy) pentyl) phosphonate, dipropyl- (6- (methacryloyloxy) hexyl ) Phosphonate, diphenyl- (methacryloyloxymethyl) phosphinate, diphenyl- (2- (methacryloyloxy) ethyl) phosphinate, diphenyl- (3- (methacrylate) Liloyloxy) propyl) phosphinate, diphenyl- (4- (methacryloyloxy) butyl) phosphinate, diphenyl- (5- (methacryloyloxy) pentyl) phosphinate, diphenyl- (6- (methacryloyloxy) hexyl) phosphinate, dimethyl- (methacryloyloxy) Methyl) phosphinate, dimethyl- (2- (methacryloyloxy) ethyl) phosphinate, dimethyl- (3- (methacryloyloxy) propyl) phosphinate, dimethyl- (4- (methacryloyloxy) butyl) phosphinate, dimethyl- (5- (methacryloyl) Oxy) pentyl) phosphinate, dimethyl- (6- (methacryloyloxy) hexyl) phosphinate, diethyl- (methacryloyloxymethyl) Sufinate, diethyl- (2- (methacryloyloxy) ethyl) phosphinate, diethyl- (3- (methacryloyloxy) propyl) phosphinate, diethyl- (4- (methacryloyloxy) butyl) phosphinate, diethyl- (5- (methacryloyloxy) Pentyl) phosphinate, diethyl- (6- (methacryloyloxy) hexyl) phosphinate, dipropyl- (methacryloyloxymethyl) phosphinate, dipropyl- (2- (methacryloyloxy) ethyl) phosphinate, dipropyl- (3- (methacryloyloxy) propyl) Phosphinate, dipropyl- (4- (methacryloyloxy) butyl) phosphinate, dipropyl- (5- (methacryloyloxy) pentyl) phosphinate Dipropyl- (6- (methacryloyloxy) hexyl) phosphinate, diphenyl- (methacryloyloxymethyl) phosphine oxide, diphenyl- (2- (methacryloyloxy) ethyl) phosphine oxide, diphenyl- (3- (methacryloyloxy) propyl) phosphine oxide , Diphenyl- (4- (methacryloyloxy) butyl) phosphine oxide, diphenyl- (5- (methacryloyloxy) pentyl) phosphine oxide, diphenyl- (6- (methacryloyloxy) hexyl) phosphine oxide, dimethyl- (methacryloyloxymethyl) Phosphine oxide, dimethyl- (2- (methacryloyloxy) ethyl) phosphine oxide, dimethyl- (3- (methacryloyloxy) propyl) phospho Sphine oxide, dimethyl- (4- (methacryloyloxy) butyl) phosphine oxide, dimethyl- (5- (methacryloyloxy) pentyl) phosphine oxide, dimethyl- (6- (methacryloyloxy) hexyl) phosphine oxide, diethyl- (methacryloyloxy) Methyl) phosphine oxide, diethyl- (2- (methacryloyloxy) ethyl) phosphine oxide, diethyl- (3- (methacryloyloxy) propyl) phosphine oxide, diethyl- (4- (methacryloyloxy) butyl) phosphine oxide, diethyl- ( 5- (methacryloyloxy) pentyl) phosphine oxide, diethyl- (6- (methacryloyloxy) hexyl) phosphine oxide, dipropyl- (methacryloyloxy) Til) phosphine oxide, dipropyl- (2- (methacryloyloxy) ethyl) phosphine oxide, dipropyl- (3- (methacryloyloxy) propyl) phosphine oxide, dipropyl- (4- (methacryloyloxy) butyl) phosphine oxide, dipropyl- ( 5- (methacryloyloxy) pentyl) phosphine oxide, dipropyl- (6- (methacryloyloxy) hexyl) phosphine oxide, diphenyl styrylphosphonate, dimethyl styrylphosphonate, diethyl styrylphosphonate, dibutyl styrylphosphonate, dipentyl styrylphosphonate, Dihexyl styrylphosphonate, diphenyl styrylmethylphosphonate (= same as diphenyl benzylphosphonate), dimethyl styrylmethylphosphonate Diethyl styrylmethylphosphonate, dibutyl styrylmethylphosphonate, dipentyl styrylmethylphosphonate, dihexyl styrylmethylphosphonate, diphenyl styrylethylphosphonate, dimethyl styrylethylphosphonate, diethyl styrylethylphosphonate, dibutyl styrylethylphosphonate, dipentylstyrylethylphosphonate, Dihexyl styrylethylphosphonate, diphenyl styrylpropylphosphonate, dimethyl styrylpropylphosphonate, diethyl styrylpropylphosphonate, dibutyl styrylpropylphosphonate, dipentyl styrylpropylphosphonate, dihexyl styrylpropylphosphonate, diphenyl styrylbutylphosphonate, styrylbutyl Dimethyl phosphonate, styryl butylphosphonic acid Diethyl, styrylbutylphosphonate dipentyl, styrylbutylphosphonate dipentyl, styrylbutylphosphonate dihexyl, styrylpentylphosphonate diphenyl, styrylpentylphosphonate dimethyl, styrylpentylphosphonate diethyl, styrylpentylphosphonate dibutyl, styrylpentylphosphonate dipentyl, Dihexyl styryl pentyl phosphonate, diphenyl styryl hexyl phosphonate, dimethyl styryl hexyl phosphonate, diethyl styryl hexyl phosphonate, dibutyl styryl hexyl phosphonate, dipentyl styryl hexyl phosphonate, dihexyl styryl hexyl phosphonate, styryl diphenyl phosphine oxide, styryl dimethyl phosphine oxide Oxide, styryldiethylphosphineoxy , Styryl dibutyl phosphine oxide, styryl dipentyl phosphine oxide, styryl dihexyl phosphine oxide, (styrylmethyl) diphenylphosphine oxide (= same as benzyldiphenylphosphine oxide), (styrylmethyl) dimethylphosphine oxide, (styrylmethyl) diethylphosphine oxide, ( (Styrylmethyl) dibutylphosphine oxide, (styrylmethyl) dipentylphosphine oxide, (styrylmethyl) dihexylphosphine oxide, (styrylethyl) diphenylphosphine oxide, (styrylethyl) dimethylphosphine oxide, (styrylethyl) diethylphosphine oxide, (styrylethyl) ) Dibutylphosphine oxide, (styrylethyl) dipentylphosphine Oxide, (styrylethyl) dihexylphosphine oxide, (styrylpropyl) diphenylphosphine oxide, (styrylpropyl) dimethylphosphine oxide, (styrylpropyl) diethylphosphine oxide, (styrylpropyl) dibutylphosphine oxide, (styrylpropyl) dipentylphosphine oxide, (Styrylpropyl) dihexylphosphine oxide, (styrylbutyl) diphenylphosphine oxide, (styrylbutyl) dimethylphosphine oxide, (styrylbutyl) diethylphosphine oxide, (styrylbutyl) dibutylphosphine oxide, (styrylbutyl) dipentylphosphine oxide, (styryl) Butyl) dihexylphosphine oxide, (styrylpentyl) diphenyl Phosphine oxide, (styrylpentyl) dimethylphosphine oxide, (styrylpentyl) diethylphosphine oxide, (styrylpentyl) dibutylphosphine oxide, (styrylpentyl) dipentylphosphine oxide, (styrylpentyl) dihexylphosphine oxide, (styrylhexyl) diphenylphosphine oxide , (Styrylhexyl) dimethylphosphine oxide, (styrylhexyl) diethylphosphine oxide, (styrylhexyl) dibutylphosphine oxide, (styrylhexyl) dipentylphosphine oxide, (styrylhexyl) dihexylphosphine oxide, vinylphosphonate compound, vinylphosphinate Compounds, vinylphosphine oxide compounds, and the like.
As the vinyl phosphonate compound, vinyl phosphinate compound, and vinyl phosphine oxide compound in which X in the general formula (1) is a single bond, a known metal catalyst such as Pd, Rh, or Ni is used. , Hydrogen phosphinic acid ester and phosphine oxide can be synthesized by addition reaction to acetylenes.

  Examples of these are, for example, vinyl dimethyl phosphonate, vinyl diethyl phosphonate, vinyl diphenyl phosphonate, methyl vinyl methyl phosphinate, ethyl vinyl ethyl phosphinate, phenyl vinyl phenyl phosphinate, vinyl dimethyl phosphine oxide, vinyl diethyl phosphine oxide. Vinyl diphenylphosphine oxide and the like, but are not limited thereto.

Examples of the monomer of the structural unit represented by the general formula (2) include acrylic acid and methacrylic acid.
The monomer of the structural unit represented by the general formula (3) is not particularly limited. For example, benzyl methacrylate, styrene, paracumylphenol EO-modified acrylate, nonylphenol PO-modified acrylate, nonylphenol EO-modified acrylate, paracumyl Examples thereof include phenol EO-modified acrylate.

Examples of the monomer of the structural unit represented by the general formula (6) include acrylic acid esters and methacrylic acid esters.
Examples of the acrylate ester and methacrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, ethylene glycol methyl ether acrylate, Glycidyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobornyl acrylate, amide acrylate, isodecyl acrylate, octadecyl acrylate, lauryl acrylate, allyl acrylate, N-acrylate Vinylpyrrolidone, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, methacrylate Isobutyl phosphate, ethylene glycol methyl ether methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobornyl methacrylate, methacrylamide, isodecyl methacrylate, octadecyl methacrylate, methacryl Examples thereof include lauryl acid, allyl methacrylate, and N-vinylpyrrolidone methacrylate. Non-acrylic acid monomers such as acrylonitrile and dimethylaminoethyl can also be used as monomers having no phosphorus in the side chain.
Moreover, monomers other than the monomer of the structural unit of General formula (1)-(3) and (6) can also be used as a copolymerization component. As such a monomer, non-acrylic acid monomers such as acrylonitrile and dimethylaminoethyl can be used.

  In order to synthesize a resin using the monomer as a raw material, it can be easily synthesized using a general polymerization initiator. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN), tert-butyl perbenzoate (PBOC), benzoyl peroxide, lauroyl peroxide, peroxides such as potassium persulfate, cumene hydroperoxide, t- Butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, 2,2′-azobis-2,4-dimethylvaleronitrile, t-butyl perisobutyrate, t-butyl perpivalate, hydrogen peroxide / primary Examples thereof include iron salt, persulfate / sodium acid sulfite, cumene hydroperoxide / ferrous iron salt, benzoyl peroxide / dimethylaniline and the like. These may be combined.

  The amount of polymerization initiator used varies depending on the type of polymerization initiator, but the polymerization rate decreases when the amount of polymerization initiator used is small, and the weight average molecular weight tends to decrease when the amount of polymerization initiator used is large. Therefore, 0.0001 to 5 parts by mass is preferable and 0.001 to 3 parts by mass is more preferable with respect to 100 parts by mass of the total amount of monomers used.

  In addition, the resin of the present application can be obtained by uniformly dissolving a monomer as a raw material in an organic solvent, or by emulsifying or suspending it in an aqueous solution. The organic solvent to be uniformly dissolved is not particularly limited as long as the raw material monomer, the polymer to be generated, and the polymerization initiator are dissolved, and examples thereof include toluene, methyl ethyl ketone, dimethylformamide, dimethylacetamide and the like.

  The optimum reaction temperature for copolymerization varies depending on the boiling point of the raw material monomer and solvent, the radical generation temperature and half-life of the polymerization initiator, and is preferably −15 ° C. to 150 ° C. from the viewpoint of production equipment and efficiency. It is more preferable to carry out at (C) -100C.

The produced polymer can be used as it is unless particularly required, but can also be purified by removing impurities by filtration, precipitation with a poor solvent, or the like. Further, in suspension polymerization and emulsion polymerization, polymerization can be performed more efficiently by using a chain transfer agent such as a dispersant, an emulsifier, and α-styrene dimer.
The weight average molecular weight (styrene conversion value by GPC method) of the resin (A) used in the present invention is preferably 1,000 to 1,000,000 from the viewpoint of heat resistance and film forming ability. 2,000 to 500,000, more preferably 3,000 to 400,000, particularly preferably 10,000 to 300,000, and 30,000 to 200,000. Most preferably. If the molecular weight is less than 1,000, problems such as bleeding out and B-stage tack (stickiness) occur in the resin composition, and the coating film of the film tends to be brittle. On the other hand, if the molecular weight exceeds 1,000,000, the resin residue after development increases, and the removal (phenomenon) of the resin in the unexposed part after photocuring described later tends to be difficult.

  The acid value of the phosphorus-containing compound is preferably 20 to 200 mgKOH / g, more preferably 30 to 180 mgKOH / g, and further preferably 40 to 150 mgKOH / g. When the acid value is less than 20 mgKOH / g, the resolution in the alkali developer tends to be insufficient, and when it exceeds 200 mgKOH / g, the electric corrosion resistance tends to be insufficient.

The resin composition according to the present invention contains the phosphorus-containing compound of the present invention and is preferably cured by light.
In the curable resin composition (resin composition) according to the present invention, the content of the phosphorus-containing compound of the present invention is 10 to 80% by mass on the basis of the total solid content in the curable resin composition. Preferably, it is 20-70 mass%. If this content is less than 10% by mass, the flame retardancy of the resulting cured product tends to be reduced, and if it exceeds 80% by mass, the photosensitivity in the case of a resin composition is reduced, resulting in resolution. And the physical properties after curing tend to be insufficient.

(B) Polymerizable compound having an ethylenically unsaturated group As the polymerizable compound having an ethylenically unsaturated group contained in the resin composition of the present invention, for example, an α, β-unsaturated carboxylic acid is added to a polyhydric alcohol. Compound obtained by reaction, 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolypropoxy) phenyl) propane, 2 , 2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) propane and other bisphenol A-based (meth) acrylate compounds and glycidyl group-containing compounds are obtained by reacting α, β-unsaturated carboxylic acids. Compounds, urethane monomers such as (meth) acrylate compounds having a urethane bond, γ-chloro-β-hydroxypropyl-β ′-(me Ta) acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, (meth) ) Acrylic acid alkyl ester and the like.

  Examples of the compound obtained by reacting the polyhydric alcohol with an α, β-unsaturated carboxylic acid include, for example, polyethylene glycol di (meth) acrylate having 2 to 14 ethylene groups and 2 to 2 propylene groups. Polypropylene glycol di (meth) acrylate being 14, polyethylene polyethylene glycol di (meth) acrylate having 2 to 14 ethylene groups and 2 to 14 propylene groups, trimethylolpropane di (meth) acrylate, Trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane diethoxytri (meth) acrylate, trimethylolpropane triethoxytri (meth) acrylate, trimethylolpropane tetraeth Xyltri (meth) acrylate, trimethylolpropane pentaethoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) having 2 to 14 propylene groups ) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like.

  Examples of the 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane include 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane, 2,2 -Bis (4-((meth) acryloxytriethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxytetraethoxy) phenyl) propane, 2,2-bis (4-((meta ) Acryloxypentaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxyhexaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxyheptaethoxy) phenyl) Propane, 2,2-bis (4-((meth) acryloxyoctaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxynonane) Xyl) phenyl) propane, 2,2-bis (4-((meth) acryloxydecaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxyundecaethoxy) phenyl) propane, 2 , 2-bis (4-((meth) acryloxydodecaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxytridecaethoxy) phenyl) propane, 2,2-bis (4- ((Meth) acryloxytetradecaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypentadecaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxy) Hexadecaethoxy) phenyl) propane and the like, and 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane is BPE- 00 (available from Shin-Nakamura Chemical Co., Ltd., trade name) and 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane is BPE-1300 (Shin-Nakamura Chemical Co., Ltd.). It is commercially available as a product name, manufactured by Co., Ltd.

  Examples of the urethane monomer include a (meth) acryl monomer having an OH group at the β-position and a diisocyanate compound 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, EO, PO-modified urethane di (meth) acrylate, and the like.

“EO” represents ethylene oxide, and an EO-modified compound has a block structure of an ethyleneoxy group.
“PO” represents propylene oxide, and the PO-modified compound has a block structure of a propyleneoxy group.

As the EO-modified urethane di (meth) acrylate, for example, trade name “UA-11” manufactured by Shin-Nakamura Chemical Co., Ltd. is commercially available.
In addition, as EO and PO-modified urethane di (meth) acrylate, for example, trade name “UA-13” manufactured by Shin-Nakamura Chemical Co., Ltd. is commercially available. You may use these individually or in combination of 2 or more types.

(C) Polymerization initiator In the curable resin composition according to the present invention, the polymerization initiator may be any one that matches the light wavelength of the exposure machine used for curing, and a known one can be used. it can. Examples of the polymerization initiator include acetophenone, benzophenone, 4,4-bisdimethylaminobenzophenone, 4,4-bisdiethylaminobenzophenone, 3,3-dimethyl-4-methoxybenzophenone, benzoin ethyl ether, benzoin butyl ether, benzoin isobutyl. Ether, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-dimethoxy-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy- 2-methylpropane, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, methylbenzoylformate, 3, , 4,4-tetra (t-butylperoxycarbonyl) benzophenone, 1,2-di-9-acridinylethane, 1,3-di-9-acridinylpropane, 1,4-di-9- Examples include acridinyl butane, 1,7-di-9-acridinylheptane, 1,8-di-9-acridinyloctane, 2,4,5-triarylimidazole dimer or derivatives thereof.

  The content of the polymerization initiator is preferably from 0.1 to 10% by mass, particularly preferably from 0.5 to 5.0% by mass, based on the total solid content in the curable resin composition.

  In the curable resin composition according to the present invention, a thermoplastic resin, a thermosetting resin, and a photocurable resin can be used alone or in combination of two or more, as long as the effects of the present invention are not lowered. Among these, the heat resistance of the curable resin composition can be improved by using a thermosetting resin or a photocurable resin.

  Examples of the thermoplastic resin include acrylic resin, methacrylic resin, phenoxy resin, polyamide, polyamideimide, polyarylate, polyetherimide, polyetheretherketone, polyethylene, polyethylene terephthalate, polysulfone, polyethersulfone, polystyrene, and polyphenylene. Examples include ether, polyphenylene sulfide, and polymethyl methacrylate. Note that by using a resin containing a carboxyl group, the solubility of the resin in an alkaline developer can be improved.

  There is no restriction | limiting in particular as a thermosetting resin, A well-known thermosetting resin can be utilized. Specifically, for example, an epoxy resin, a phenol resin, an alkyd resin, a melamine resin, an isocyanate resin, or the like can be used, and those curing agents or curing accelerators are appropriately blended. For example, when an epoxy resin is used as the thermosetting resin, the curing agent is not particularly limited, and amines, phenols, acid anhydrides, and the like are used.

  Here, as amines, dimethylamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, aminoethylpiperazine, mensendiamine, metaxylylenediamine, dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, methylenedianiline, metaphenylenediamine Etc.

  Examples of the phenols include biphenol, bisphenol-A, bisphenol-F, phenol novolak, cresol novolak, bisphenol A novolak, and alkyl group-substituted products thereof.

  Acid anhydrides include hexahydrophthalic anhydride (HPA), tetrahydrophthalic anhydride (THPA), pyromellitic anhydride (PMDA), dodenyl succinic anhydride (DDSA), phthalic anhydride (PA), methylhexahydrophthalic anhydride Examples include acid (MeHPA) and maleic anhydride. These curing agents may be used alone or in combination of two or more.

  Moreover, as an accelerator when using an epoxy resin as a thermosetting resin, an imidazole compound, an organophosphorus compound, a tertiary amine, a quaternary ammonium salt, a secondary amino group with acrylonitrile, isocyanate, melamine, acrylate An imidazole compound masked with, for example, can be used, and the addition amount is preferably 0.1 to 6 parts by mass with respect to 100 parts by mass of the epoxy resin. If this addition amount is less than 0.1 parts by mass, the effect of promoting curing is small, and if it exceeds 6 parts by mass, the storage stability of the curable resin composition tends to decrease.

  As the imidazole compound used here, imidazole, 2-methyl-imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 4,5 -Diphenylimidazole, 2-methylimidazoline, 2-ethyl-4methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl- Examples include 4-methylimidazole, 2-methylimidazoline, 2-isopropylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline.

Moreover, as a resin used for the curable resin composition, an unsaturated polyester resin, a copolymer having a functional group that can be cross-linked by the above-described polymerization initiator, a compound equivalent to a monomer, or the like can be used. .
A resin that is polymerized with heat or a thermal polymerization initiator can also be used.

  A well-known thing can be utilized as a thermal-polymerization initiator. For example, ketone peroxides such as benzoyl peroxide and methyl ethyl ketone peroxide, alkyl peroxides such as tertiary butyl peroxide, peroxydicarbonates, peroxyketals, peroxyesters, alkylperesters, etc. Can be used.

The content in the case of using a thermal polymerization initiator in the resin composition of the present invention is preferably 0.1 to 10% by mass based on the total solid content in the curable resin composition, and preferably 0.5 to 5%. It is more preferable to set it as the mass%.
Specific examples of the photo-curable resin include epoxy (meth) acrylate obtained by adding acrylic acid and / or methacrylic acid to a diglycidyl ether compound of bisphenols, and acrylic acid and / or methacrylic acid added to a novolac type epoxy resin ( Examples thereof include a (meth) acryl-modified novolak epoxy resin and a resin obtained by adding glycidyl acrylate and / or glycidyl methacrylate to an acrylic resin having a carboxyl group.

  In addition, when an epoxy resin is used for the curable resin composition according to the present invention, after adding acrylic acid and / or methacrylic acid to the epoxy resin, physical properties such as resolution and moisture resistance insulation are not reduced. The modification may be performed with an acid anhydride.

Examples of the acid anhydride include carboxylic acid anhydride, maleic acid anhydride, tetrahydrophthalic acid anhydride, itaconic acid anhydride, hexahydrophthalic acid anhydride, succinic acid anhydride, naphthalic acid anhydride, citraconic acid anhydride. Methylphthalic anhydride, butenyltetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, alkenyl anhydride, tricarbanilic anhydride, and the like.
Moreover, the curable resin composition of this invention may contain the copolymer and / or monomer which have the functional group which can be bridge | crosslinked with a cationic photoinitiator. Such a copolymer and / or monomer is not particularly limited as long as it performs cationic polymerization. For example, a compound having a polymerizable vinyl ether group, propenyl ether group, epoxy group, or oxetanyl group in the molecule can be used. Can be mentioned.

  Examples of the cationic photoinitiator include known ones such as triphenyl sulfone hexafluoroantimonate, triphenyl sulfone hexafluorophosphate, p-methoxybenzenediazonium hexafluorophosphate, p-chlorobenzenediazonium hexafluorophosphate, diphenyl. Examples include iodonium hexafluorophosphate, 4,4-di-t-butylphenyl iodonium hexafluorophosphate, (1-6-n-cumene) (n-dicopentadiniel) iron hexafluorophosphate, and the like. The content of these radical photoinitiators or cationic photoinitiators is preferably 0.1 to 10% by mass, based on the total solid content in the curable resin composition, respectively. More preferably, it is 5.0 mass%.

  Moreover, you may add a thermosetting agent to the resin composition of this invention in the range which does not inhibit the effect obtained by this invention. Such a thermosetting agent is not particularly limited. For example, a thermosetting agent that itself crosslinks by heating, that is, a curing agent that forms a polymer network by applying heat, or a curable resin composition. In the case where a resin having a carboxyl group is used as the resin used in the above, a curing agent that reacts with the carboxyl group of the resin by heating to form a three-dimensional structure is exemplified.

A bismaleimide compound is mentioned as a thermosetting agent which bridge | crosslinks itself by heating.
As bismaleimide compounds, m-di-N-maleimidylbenzene, bis (4-N-maleimidylphenyl) methane, 2,2-bis (4-N-maleimidylphenyl) propane, 2,2 -Bis (4-N-maleimidyl 2,5-dibromophenyl) propane, 2,2-bis [4- (4-N-maleimidylphenoxy) phenyl] propane, 2,2-bis (4-N-malemidyl) Various bismaleimide compounds such as 2-methyl-5-ethylphenyl) propane are used as they are or as a mixture. These bismaleimide compounds can be used either alone or modified with various resins.

  In the resin composition, a blocked isocyanate compound can also be used as a curing agent that reacts with the carboxyl group of the resin by heating to form a three-dimensional structure.

  Examples of the blocked isocyanate compound include polyisocyanate compounds blocked with a blocking agent such as an alcohol compound, a phenol compound, ε-caprolactam, an oxime compound, and an active methylene compound.

  Examples of blocked polyisocyanate compounds include 4,4-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylene diisocyanate, and m-xylene diisocyanate. Aromatic polyisocyanates such as 2,4-tolylene dimer, aliphatic polyisocyanates such as hexamethylene diisocyanate, 4,4-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate, and alicyclic polyisocyanates such as bicycloheptane triisocyanate. An aromatic polyisocyanate is preferable from the viewpoint of heat resistance, and an aliphatic polyisocyanate or an alicyclic polyisocyanate is preferable from the viewpoint of preventing coloring.

Moreover, you may add a filler to the resin composition by this invention in the range which does not reduce resolution, a flame retardance, and the elongation rate of hardened | cured material.
Examples of the filler include silica, fused silica, talc, alumina, hydrated alumina, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, aerosil, calcium carbonate, and other inorganic fine particles, powdered epoxy resin, and powdery Examples thereof include organic fine particles such as polyimide particles, and powdered polytetrafluoroethylene particles. These fillers may be subjected to a coupling treatment in advance.

  Dispersion of these fillers is achieved by a known kneading method such as a kneader, a ball mill, a bead mill, or a three roll. The content of these fillers is preferably 2 to 20% by mass, more preferably 5 to 15% by mass, based on the total solid content in the curable resin composition.

The resin composition according to the present invention can be used by diluting in a solvent when forming a resin composition layer.
Examples of the solvent include ketone compounds such as methyl ethyl ketone, acetone and cyclohexanone, aromatic hydrocarbon compounds such as xylene and toluene, amide compounds such as N, N-dimethylformamide and N, N-dimethylacetamide, and the like. . These solvents can be used alone or in admixture of two or more.

  In order to efficiently dissolve the resin composition, ethylene glycol monoethyl ether, ethyl ethoxypropionate, or the like may be used as a solvent in accordance with the solubility of the composition, and these may be added to other solvents. Also good.

  It is preferable that the compounding quantity of the solvent in a resin composition is 10-200 mass parts with respect to 100 mass parts of components (solid content) other than the solvent in a resin composition, and it is more preferable that it is 30-100 mass parts. preferable. When the blending amount of the solvent is less than 10 parts by mass, the viscosity of the resin composition tends to increase, and therefore, it tends to be difficult to mix uniformly. On the other hand, when the amount of the solvent exceeds 200 parts by mass, it tends to be difficult to control the thickness of the layer when the curable resin composition layer is formed due to a decrease in viscosity, and the use of the solvent There is a tendency to be expensive due to the large amount.

  A polymerization stabilizer, a leveling agent, a pigment, a dye, and an adhesion improver may be further added to the resin composition. These selections are made under the same considerations as for ordinary curable resin compositions. These addition amounts are such that the properties of the resin composition of the present invention are not impaired, and each is added so as to have a content of 0.01 to 10% by mass based on the total solid content in the resin composition. Is preferred.

  There is no restriction | limiting in particular about the thickness of the resin composition layer formed using the resin composition by this invention, In the range of 10-150 micrometers, it selects suitably. The resin composition is coated directly on the substrate or printed wiring board by a conventional method such as dip coating, roll coating, flow coating, screen printing, spraying, electrostatic spraying, etc. Although it is possible to easily form a resin composition layer comprising the above resin composition, it may be used as a photosensitive film for a permanent resist as described later.

The resin composition according to the present invention can be used for formation of resist patterns such as photosensitive films and permanent resists, printed wiring boards, and the like.
Moreover, the resin composition of this invention can be used suitably for formation of said photosensitive film and a resist pattern, and a printed wiring board by having photocurability.

Next, the photosensitive film according to the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing a preferred example of the photosensitive film of the present invention. A photosensitive film 1 shown in FIG. 1 is a photosensitive film for a permanent resist, and includes a resin composition layer 12 made of the resin composition according to the present invention on a support (carrier film) 11, and further photosensitive. A cover film (protective film) 13 is provided on the surface of the resin composition layer 12 opposite to the support (carrier film) 11.

  The support (carrier film) 11 is not particularly limited as long as it can support the resin composition layer 12 and further the cover film 13. For example, a polyester film, polyimide film, polyamideimide film, polypropylene film, polystyrene film Etc. are preferably used. The support 11 may have a single layer structure or may have a multilayer structure in which films having a plurality of compositions are laminated. Furthermore, the surface of the support 11 opposite to the resin composition layer 12 may be subjected to treatment such as embossing and corona treatment.

  Although there is no restriction | limiting in particular in the thickness of the support body (carrier film) 11, The range of 2-150 micrometers is preferable, The range of 5-100 micrometers is more preferable, The range of 8-20 micrometers is more preferable, The range of 10-16 micrometers is especially preferable. . If the thickness is less than 2 μm, the support (carrier film) 11 tends to be broken when the support (carrier film) 11 is peeled and removed from the photosensitive film 1. If the thickness exceeds 150 μm, the flexibility of the photosensitive film 1 as a whole is increased. Tend to be reduced, and the ability to follow unevenness on the surface of the object to be laminated tends to be reduced.

  As a method of forming the resin composition layer 12 on the support (carrier film) 11, a coating liquid containing the resin composition according to the present invention is applied on the support (carrier film) 11 with a comma coater, a blade coater, and a lip coater. Examples of the method include applying a uniform thickness with a rod coater, squeeze coater, reverse coater, transfer roll coater, etc., and heating and drying to volatilize the solvent. There is no restriction | limiting in particular about the thickness of the formed resin composition layer, It selects suitably in the range of 10-150 micrometers.

  The cover film 13 is used as a protective film and is peeled off before laminating. Therefore, the cover film 13 has flexibility and can be peelably bonded to the resin composition layer 12 and is not damaged at the temperature of the drying furnace. If it is, there will be no restriction | limiting in particular, For example, a polyethylene film, a polypropylene film, a polytetrafluoroethylene film, surface-treated paper etc. are mentioned.

  The cover film 13 has an adhesive force between the resin composition layer 12 and the cover film 13 rather than an adhesive force between the resin composition layer 12 and the support 11 so that the cover film 13 can be easily peeled from the resin composition layer 12. It is preferable that is smaller.

  Although there is no restriction | limiting in particular in the thickness of the cover film 13, when the point of the size at the time of winding in roll shape is considered, it is preferable to set it as 10-30 micrometers, it is more preferable to set it as 10-25 micrometers, and 10-20 micrometers. More preferably.

  According to the photosensitive film 1, the resin composition layer 12 is overlaid on a substrate or a printed wiring board, and pasted using a hot roll laminator or the like, whereby the resin composition of the permanent resist film on the substrate or the wiring board. The layer 12 can be easily formed.

  Moreover, exposure and image development of the formed resin composition layer 12 can be performed by a conventional method. For example, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, or the like is used as a light source, and imagewise exposure can be performed through a negative mask directly on the resin composition layer 12 or through a transparent film such as a polyethylene terephthalate film. When a transparent film remains after exposure, it is preferable to develop the film after peeling it off.

The resin composition of the present invention can also form an image resin film by a printing method, a laser drilling method using a carbon dioxide laser, a YAG laser, an excimer laser, or the like.
The above-described resin composition and photosensitive film have no problem of bleeding during heating without using a halide, can ensure flame retardancy, and are excellent in resolution and elongation of a cured product. A resist can be formed.
In addition, the photosensitive film which becomes this invention is not restrict | limited to the above-mentioned thing, For example, what does not have the cover film 13 may be used.

Next, a resist pattern forming method according to the present invention will be described.
The resist pattern forming method according to the present invention has at least photosensitivity so as to cover the conductor layer on the insulating substrate of the laminated substrate including the insulating substrate and the conductor layer having the circuit pattern formed on the insulating substrate. A resin composition layer comprising the resin composition according to the present invention is formed, and an exposed portion is formed by irradiating a predetermined portion of the resin composition layer with an actinic ray, and other than the exposed portion of the photosensitive resin composition layer It is a method of removing a part.

  As a method for laminating the resin composition layer, the method of directly coating the resin composition of the present invention on the insulating substrate and the insulating substrate while heating the resin composition layer 12 in the photosensitive film 1 of the present invention described above. For example, a method of laminating by pressure bonding to the substrate can be exemplified. Therefore, when the curable resin composition contains a volatile component such as a solvent, the resin composition layer laminated on the substrate is mainly composed of the component after most of the solvent is removed.

  After the lamination is completed in this manner, an exposed portion is formed by irradiating a predetermined portion of the resin composition layer with an actinic ray (exposure step). Examples of the method for forming the exposed portion include a method of irradiating actinic rays in an image form through a negative or positive mask pattern called an artwork. At this time, the mask may be directly contacted on the resin composition layer or may be contacted via a transparent film.

  As the actinic ray light source, a known light source is used. For example, a light source that effectively emits ultraviolet rays, such as a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, or a xenon lamp, is used. Moreover, what emits visible light effectively, such as a photographic flood light bulb and a solar lamp, is also used.

After the exposure, an alkali developer is used, and development is performed by removing portions other than the exposed portion by a known method such as spraying, rocking immersion, brushing, and scraping to form a resist pattern (developing step). Note that after the resist pattern is formed, post-curing may be further performed by exposure at 1 to 5 J / cm ² and / or heating at 100 to 200 ° C. for 30 minutes to 12 hours (post-heating step).

  The developer used in the development process is an alkali developer as a standard, but there is no particular limitation on the type of the developer as long as it does not damage the exposed part and selectively elutes the unexposed part. It is determined depending on the development type of the composition, and general ones such as an alkali developer, a semi-aqueous developer, and a solvent developer can be used. For example, an emulsion developer containing water and an organic solvent can be used.

  Particularly useful emulsion developers include, for example, propylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, 2,2-butoxyethoxyethanol, butyl lactate, cyclohexyl lactate, ethyl benzoate, and 3-methyl-3 as organic solvent components. An emulsion developer containing 10 to 40% by mass of an organic solvent such as methoxybutyl acetate can be mentioned.

  When an alkali developer is used, an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, sodium 4-borate, ammonia, amines and the above organic solvent It is also possible to use an emulsion developer.

  By the above-described method, a resist pattern can be formed on the photosensitive resin composition layer laminated on the conductor layer on which the circuit pattern is formed. The photosensitive resin composition layer on which the resist pattern is formed can be used as a solder resist for preventing solder from adhering to unnecessary portions on the conductor layer at the time of mounting components.

Next, the printed wiring board and the manufacturing method thereof according to the present invention will be described.
FIG. 2 is a schematic cross-sectional view showing an example of the printed wiring board of the present invention. The printed wiring board 2 shown in FIG. 2 includes an insulating substrate 22, a conductor layer 23 having a circuit pattern formed on one surface of the insulating substrate 22, and a circuit pattern formed on the other surface of the insulating substrate 22. A resist layer 24 formed on the insulating substrate 22 is provided so as to cover the conductor layer 21 that does not have and the conductor layer 23 that has a circuit pattern.

  The resist layer 24 is made of a cured product of the resin composition layer in the photosensitive film according to the present invention, and the resist layer (resin composition layer) 24 has at least a part of the conductor layer 23 having a circuit pattern. An opening 26 is provided so as to be exposed. The resist layer (resin composition layer) 24 may be formed by applying the curable resin composition according to the present invention on the insulating substrate 22 and curing it.

  Since the printed wiring board 2 has the opening 26, a mounting component such as CSP or BGA can be joined to the conductor layer 23 having a circuit pattern by solder or the like, and so-called surface mounting becomes possible. The resist layer (resin composition layer) 24 has a role as a solder resist for preventing the solder from adhering to unnecessary portions of the conductor layer during soldering for bonding. After mounting component bonding, it functions as a permanent mask for protecting the conductor layer 23 having a circuit pattern.

  FIG. 3 is a process diagram showing a method of manufacturing the printed wiring board 2 shown in FIG. 3A shows an insulating substrate 22 having a conductor layer 23 having a circuit pattern on one side and a conductor layer 21 having no circuit pattern on the other side. FIG. 3B and FIG. FIG. 3D shows that the printed wiring board 4 after the resist layer (resin composition) 24 is laminated on the insulating substrate 22 and the resist layer (resin composition layer) 24 are irradiated with actinic rays. The printed wiring board 2 after development is shown.

  First, the pattern of the conductor layer 23 having a circuit pattern on the insulating substrate 22 is formed by a known method of etching one side of a double-sided metal laminate (for example, a double-sided copper-clad laminate) as shown in FIG. The printed wiring board 3 in which the conductor layer 23 having the circuit pattern is formed is obtained.

  Next, on the double-sided metal-clad laminate 3 on which the conductor layer 23 having a circuit pattern is formed as shown in FIG. 3B, the photosensitive layer according to the present invention is formed so as to cover the conductor layer 23 having a circuit pattern. A resist layer (resin composition layer) 24 made of a resin composition of a film is laminated to obtain a printed wiring board 4 on which the resist layer (resin composition layer) 24 is laminated.

  Next, the resist layer (photosensitive resin composition) 24 is irradiated with actinic rays through a mask 5 having a predetermined pattern on the resist layer (resin composition layer) 24 laminated as shown in FIG. Layer) A predetermined portion of 24 is cured.

  Finally, by removing the unexposed portions, a printed wiring board 2 is obtained by forming a resist layer (resin composition layer) 24 having openings 26 as shown in FIG. When the resin composition contains a volatile component such as a solvent, the resist layer (resin composition layer) 24 is a cured product of the resin composition after most of the volatile component is removed. .

  In addition, lamination | stacking of the resist layer (resin composition layer) 24 on the insulated substrate 22, irradiation of actinic light, and removal of an unexposed part can be performed by the method similar to the case in the formation method of the above-mentioned resist pattern. .

  According to such a printed wiring board, it is possible to ensure sufficient flame retardancy without using a halogen-based flame retardant, because the cured product as the constituent material is made of the curable resin composition of the present invention. In addition, sufficient PCT resistance can be obtained, and a highly reliable printed wiring board can be realized.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not restrict | limited to a following example.
[Synthesis example]
50 parts by weight of dimethylacetamide was placed in a 500 ml four-necked flask and heated to 80 ° C. with stirring under a nitrogen stream.

  On the other hand, the compounding (mol) ratio shown in Table 1 and 1% by mass of AIBN (azoisobutyronitrile) as a radical polymerization initiator were dissolved in 50 parts by mass of dimethylacetamide, which is an organic solvent, at room temperature. A phosphorus compound (copolymer) formed by dropping dropwise over 30 minutes while keeping the liquid temperature at 80 ° C. in the four-necked flask and further reacting at the same temperature for 300 minutes, and repeating units are randomly copolymerized. A dimethylacetamide solution was obtained.

  As polymer properties of the phosphorus compound obtained by synthesis, the acid value (KOH mg / g), phosphorus content (%), and weight average molecular weight (Mw) are also shown in Table 1. Each characteristic was measured as follows.

(Phosphorus content)
The phosphorus compound obtained by synthesis was applied onto a 35 mm square MCL and then dried at 170 ° C. for 1 hour to obtain a polymer film in which the solvent and the unreacted monomer were volatilized. This sample was measured for the X-ray intensity of the P element in the phosphorus compound using a fluorescent X-ray measuring device, and the P content in the phosphorus compound was determined from the X-ray intensity.

(Weight average molecular weight)
The weight average molecular weight (Mw) of the phosphorus compound obtained by synthesis was determined by gel permeation chromatography (GPC). The molecular weight was converted with a molecular weight / elution time curve prepared with standard polystyrene. The column used was Gelpack GL-S3000MDT-5 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and the eluent was a mixed eluent of dimethylformamide / tetrahydrofuran = 1/1.

ＭＥＤＰＰ：２−（メタクリルオキシ）エチルジフェニルホスフィネート（城北化学株式会社製）
ＭＡＡＣ：メタクリル酸（関東化学工業株式会社製）
ＭＭＥＣ：メタクリル酸メチル（関東化学工業株式会社製）
ＭＢｚＥＣ：メタクリル酸ベンジル（関東化学工業株式会社製）
Ｍ１１０：パラクミルフェノールＥＯ変性アクリレート（東亜合成化学工業株式会社製）
Ｍ１１７：ノニルフェノールＰＯ変性アクリレート（東亜合成化学工業株式会社製）

MEDPP: 2- (methacryloxy) ethyldiphenylphosphinate (manufactured by Johoku Chemical Co., Ltd.)
MAAC: Methacrylic acid (manufactured by Kanto Chemical Industry Co., Ltd.)
MMEC: Methyl methacrylate (manufactured by Kanto Chemical Co., Ltd.)
MBzEC: benzyl methacrylate (manufactured by Kanto Chemical Co., Ltd.)
M110: paracumylphenol EO-modified acrylate (manufactured by Toa Gosei Chemical Co., Ltd.)
M117: Nonylphenol PO-modified acrylate (manufactured by Toa Gosei Chemical Co., Ltd.)

[Examples and Comparative Examples]
As shown below, the phosphorus compounds of Synthesis Examples 1 to 8 and various materials were blended to prepare a photosensitive resin composition.
-Phosphorus compound of synthesis example: 70 parts by mass (solid content)
Photopolymerization monomer (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-321M): 30 parts by mass (solid content)
Photopolymerization initiator (Ciba Geigy Co., Ltd., trade name: Irgacure 651): 5 parts by mass (solid content)
-Thermal polymerization initiator (Nippon Yushi Co., Ltd., trade name: Perhexine 25B): 2 parts by mass (solid content)
Thermosetting agent (2,2-bis [4- (4-N-maleimidinylphenoxy) phenyl] propane, manufactured by Hitachi Chemical Co., Ltd.): 10 parts by mass (solid content)
-Methyl ethyl ketone: 20 mass parts The photosensitive resin composition by which the obtained photosensitive resin composition was coated on PET film, and was dried at 80 degreeC for 20 minutes, and the 40-micrometer-thick resin composition layer was formed on PET film A characteristic film was obtained. The following evaluation tests were performed on the photosensitive films of Examples 1 to 5 and Comparative Examples 1 to 3 thus obtained.

(Dust of photosensitive film)
The obtained photosensitive film is observed with the naked eye, and a transparent film means ◯ and a cloudy film means x.

(Resolution)
Glass cloth base epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, manufactured by Hitachi Chemical Co., Ltd., trade name: MCL-BE-67G) having a double-sided roughened foil on both sides is etched on one side. A circuit board having a circuit layer on which a comb-shaped circuit having a line width / space width (40 μm / 40 μm) dimension was formed was produced. Next, the photosensitive film obtained in Examples 1-5 and Comparative Examples 1-3 was laminated | stacked on the circuit board using the laminator, and the photosensitive resin composition layer with a film thickness of 40 micrometers was formed. Next, the resin composition layer was irradiated with UV light having an exposure amount of 200 mJ / cm ² through a photomask having a shielding portion with a diameter of 150 μm in the opening portion, and after peeling the PET film, 1% by mass A resist pattern was prepared by spraying at 30 ° C. for 1 minute using an alkali developer containing sodium carbonate.
The opening of the resist pattern thus formed was evaluated with a metal microscope. In the table, ○ means that the developability is good (no resin remains on the substrate surface), and x means that the developability is poor (a little resin remains on the substrate surface). means.

(Flame retardancy evaluation test)
Etching was performed on the entire surface of a glass cloth base epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, manufactured by Hitachi Chemical Co., Ltd., trade name: MCL-BE-67G) having double-sided roughened foil on both sides. A substrate without a circuit layer was produced. Next, the photosensitive films obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were laminated on the substrate using a laminator so as to come into contact with the etched surface of the substrate, and the film A photosensitive resin composition layer having a thickness of 40 μm was formed. Next, the resin composition layer on the substrate was irradiated with ultraviolet rays having an exposure amount of 200 mJ / cm ² , and then the PET film was peeled off. Next, with respect to the resin layer (resist) obtained by curing the resin composition layer on the substrate, a metal halide lamp type conveyor type exposure machine (lamp output 80 W / cm ² , lamp height 80 cm, no cold mirror, conveyor speed 1.5 m) / Min) was used to irradiate ultraviolet rays of 1000 mJ / cm ² to perform post-exposure.

Furthermore, the resin composition layer was completely cured by post-heating at 160 ° C. for 1 hour to obtain a cured product. And the flame retardant test piece of Examples 1-5 and Comparative Examples 6-8 was obtained by cut | disconnecting the obtained hardened | cured material to width 13mm and length 130mm. Using the test pieces (5 pieces each) thus obtained, the vertical combustion test was conducted 5 times in accordance with the UL94 standard. The total combustion time (seconds) is obtained by summing up the five combustion times, and according to the criteria of UL94 standard, V-0, V-1, V-2 and burned (burned up to the specimen clamp) Judged by rank.
Table 2 shows the relationship between the phosphorus compounds used in the examples and comparative examples, and the results of various characteristic evaluations.

When the photosensitive films of Examples 1 to 5 are used, the film after the formation of the photosensitive film does not become turbid, a transparent photosensitive film is obtained, and both resolution and flame retardancy can be ensured. it is obvious.
In contrast, in Comparative Example 1, turbidity of the film after formation of the photosensitive film did not occur, but because the acid value was 0 KOHmg / g, there was no resolution, and in Comparative Examples 2 and 3, Since the general formula (3) is not contained in the phosphorus compound, the turbidity of the film after the formation of the photosensitive film is generated, so that it is assumed that the compatibility of the resin composition is poor, and therefore, at the time of ultraviolet irradiation The dispersion of ultraviolet rays and the solubility in an alkali developer are lowered, and sufficient resolution cannot be ensured.

It is a schematic cross section which shows an example of the photosensitive film which becomes this invention. It is a schematic cross section which shows an example of the printed wiring board of this invention. (A)-(d) is process drawing which shows the manufacture process of the printed wiring board shown in FIG. 2, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive film 2, 3, 4 Printed wiring board 5 Photomask 11 Support body 12 Photosensitive resin composition layer 13 Cover film 21 Conductor layer 22 without a circuit pattern Insulating substrate 23 Conductor layer 24 with a circuit pattern Resist layer ( Photosensitive resin composition layer)
26 opening

Claims (6)

(A) a resin having a repeating unit represented by the following general formulas (1), (2) and (3), (B) a photopolymerizable compound having an ethylenically unsaturated group, and (C) a polymerization initiator Resin composition.

[In the formula (1), X represents a single bond or a divalent organic group, and R ¹ and R ² each independently represent a hydroxyl group, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, or an alkyl group having 1 to 3 carbon atoms. An alkyloxy group, an aryl group or an aryloxy group; and R ³ represents a hydrogen atom or a methyl group. In formula (2), R ⁴ represents a hydrogen atom or a methyl group. In formula (3), Y represents a single bond or an aliphatic hydrocarbon group having 1 to 6 carbon atoms and an organic group represented by the following general formula (4), and R ⁵ each independently represents a hydrogen atom or a methyl group. R ⁶ represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms, a phenyl group, a benzyl group, or an organic group represented by the following general formula (5), and n represents an integer of 1 to 5. ]

[In Formula (4), l shows the integer of 0-20, m shows the integer of 0-20, and either one of l and m is 1 or more. ]

[In Formula (5), R ⁷ represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a hydroxy group, an amino group, a cyano group, or an alkoxy group having 1 to 5 carbon atoms, and p is 1 to 5 Indicates an integer. ] The resin composition according to claim 1, which is a resin having a repeating unit represented by the following general formula (6) in addition to the repeating units represented by the general formulas (1), (2) and (3).

Wherein (6), ^{R 8} represents a hydrogen atom or a methyl group, ^{R 9} represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms. ] The resin composition according to claim 1 or 2, wherein X in the general formula (1) is any one of the following general formulas (7) to (11).

[In Formula (7), a shows the integer of 1-10. ]

Wherein (8), ^{L 1} represents an alkylene group having 1 to 3 carbon atoms. ]

Wherein (9), ^{L 2} represents an alkylene group having 1 to 3 carbon atoms. ]

[In formula (10), b shows the integer of 1-10. ]

[In formula (11), c represents an integer of 1 to 10. ]   The photosensitive film provided with the resin composition layer which consists of a resin composition in any one of Claims 1-3 formed on the support body and this support body.   From the resin composition according to any one of claims 1 to 3 so as to cover the conductor layer on the insulating substrate of a laminated substrate including an insulating substrate and a conductor layer having a circuit pattern formed on the insulating substrate. Forming a resin composition layer, irradiating a predetermined portion of the resin composition layer with actinic rays to form an exposed portion, and removing a portion other than the exposed portion of the resin composition layer. A method for forming a resist pattern.   A printed wiring board comprising an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a resist layer formed on the insulating substrate so as to cover the conductor layer, wherein the resist layer is claimed The printed wiring board which consists of hardened | cured material of the resin composition in any one of claim | item 1-3, and has an opening part so that a part of said conductor layer may be exposed.

Images