JP4849680B2 - Photosensitive resin composition and photosensitive resin laminate using the same - Google Patents

Description

  The present invention relates to a liquid resist used for a photoresist for forming a printed wiring board and a solder resist that is a protective film for a printed wiring board, a photosensitive resin composition used as a material for a dry film, and the photosensitive resin composition as a photoresist. The present invention relates to a photosensitive resin laminate as a layer. More specifically, a photosensitive resin composition capable of providing a non-filler liquid type and dry film type solder mask resist that can be suitably used as a circuit board for suspension of a hard disk drive (HDD), and a photosensitivity using the same The present invention relates to a resin laminate.

Photosensitive resins are used as materials for printing plates and photoresists. In recent years, photosensitive resins have been used not only for printed wiring board manufacturing processes, but also as solder resists that are permanent protective films for printed wiring boards.
As a solder resist, not only the characteristics required as a photoresist for circuit board formation, that is, sensitivity, resolution, photosensitivity such as resolving power, developability, and etching resistance, but also solder heat resistance that can withstand soldering, and for flexible printed circuit boards High flexibility (circuit followability) is required so that cracks do not enter when bent.

  The solder resist is roughly classified into a liquid type provided as a resist ink applied at a circuit manufacturing site and a dry film type laminated on a circuit board.

  With liquid resists, it is difficult to control the thickness of the film because it cannot be used for tenting circuit through-holes, and it must be coated and dried to form a coating, especially at the circuit manufacturing site. Since there are many troubles in quality control, such as being easy to form a hole, it tends to be preferred to be provided as a dry film at the manufacturing site.

In the case of the dry film type, it is necessary to laminate it in a state where it is in close contact with a circuit board having a step such as a copper wiring pattern. Usually, a vacuum laminator is used, and the dry film is preferably heated to be flexible. Is applied to the copper wiring pattern by using a vacuum laminator.
However, when laminating with a vacuum laminator, it is difficult to handle the dry film due to vacuuming, and the air is not sufficiently vented between the dry film and the circuit board. Tend to occur. Such a problem is more likely to occur as the surface tack (stickiness) of the photosensitive resin composition increases. Therefore, in addition to the above-mentioned properties generally required for solder resist photosensitive resins, the surface tack (surface tack) can be easily applied to the photosensitive resin composition for dry film so that the laminating operation can be easily performed. The stickiness is required to be small.

As a method for reducing the stickiness of the dry film resist, there are mainly (1) a method for increasing the polymer component ratio and (2) a method for adding a filler.
In the method (1), since the content ratio of the relatively photopolymerizable monomer is reduced, as a result, basic characteristics as a photoresist such as resolution and developability are deteriorated. As a result, voids are likely to be formed in the cured body, resulting in poor insulation properties.

  As the method (2), inorganic fillers such as silica, phosphorus compounds, halogen compounds, and antimony compounds are generally used because they can impart heat resistance and flame retardancy. For example, the photosensitive resin composition used in the solder resist dry film disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2000-47381) contains fumed silica (Syloid (registered trademark) 7000). ing.

  However, since inorganic fillers such as silica do not participate in the crosslinking reaction of the resin composition, they cannot be a part of the structural unit of the cured polymer and generally have low compatibility with the polymer. Therefore, it exists as a state physically dispersed in the cured body. For this reason, there is a problem that a photoresist containing an inorganic filler cannot be used as a solder resist that requires high cleanliness like a circuit board for HDD suspension. In other words, the HDD suspension circuit board is usually subjected to ultrasonic cleaning in order to satisfy the requirements for cleanliness. During this ultrasonic cleaning, the filler dispersed in the cured photoresist is removed. There is a risk that the cleanliness of the product may be hindered.

On the other hand, a photosensitive resin composition and a photosensitive film with a reduced surface tack have been proposed by devising the type of monomer and the type of base polymer.
For example, Patent Document 2 (Japanese Patent Laid-Open No. 2003-149803) proposes to use a special modified polyimide resin as a base polymer. Patent Document 3 (Japanese Patent Laid-Open No. 2006-293264) proposes the use of an ethylenically unsaturated bond-containing compound having a methyl group at the α-position as a monomer for photopolymerization.

  However, in the above Patent Documents 2 and 3, the evaluation of the surface tack (stickiness) is limited, and the vacuum laminating property of the obtained dry film, further flexibility, and the followability of the circuit board are not evaluated. . In particular, in a solder resist dry film used for a flexible substrate, flexibility and circuit board followability are important characteristics.

JP 2000-47381 A JP 2003-149803 A JP 2006-293264 A

  The present invention has been made in view of such circumstances, and its purpose is to provide solvent resistance, flame retardancy, flexibility, followability to conductor circuits, developability, solder heat resistance without containing fillers. It is providing the photosensitive resin composition useful for the soldering resist dry film which is a resin composition which can ensure the above, and also satisfy | fills a vacuum laminating property, and the photosensitive resin laminated body using this.

The present invention relates to a photosensitive resin composition comprising a base polymer (A), a photopolymerizable ethylenically unsaturated bond-containing compound (B), and a photopolymerization initiator (C). By using a phosphorus-containing ethylenically unsaturated compound (B1) having a specific structure and an epoxy (meth) acrylate compound (B2) having two or more hydroxyl groups in the molecule as the bond-containing compound (B), Even without the addition of any inorganic material, it can provide a dry film with less stickiness and excellent vacuum laminating properties, solvent resistance, flame resistance, flexibility, followability to conductor circuits, developability, solder heat resistance Some have been made by finding that a solder resist having excellent properties can be provided.

That is, the gist of the present invention is a photosensitive resin composition comprising a base polymer (A), a photopolymerizable ethylenically unsaturated bond-containing compound (B), and a photopolymerization initiator (C). The ethylenically unsaturated bond-containing compound (B) comprises a phosphorus-containing ethylenically unsaturated compound (B1) and an epoxy ((meth) acrylate compound (B2) having two or more hydroxyl groups in the molecule,
Polyester oligomer (a) in which the phosphorus-containing ethylenically unsaturated compound (B1) is a polycondensation of a polyvalent carboxylic acid, a polyhydric alcohol, and a phosphorus compound having an ester-forming functional group, a hydroxyl group and / or a carboxyl The present invention relates to a photosensitive resin composition which is a reaction product with an ethylenically unsaturated compound (b) having a group , and a photosensitive resin laminate formed using the same.

  The photosensitive resin composition of the present invention is required as a solder resist for solvent resistance, flame retardancy, flexibility, followability to conductor circuits, developability, solder heat resistance, etc., even without containing an inorganic filler. The dry film excellent in vacuum laminating property can be provided.

Hereinafter, the present invention will be described in detail.
In the present specification, “(meth) acryl” means both acryl and methacryl, and “(meth) acrylate” means both acrylate and methacrylate. When there is nothing to do, it is a general term.
In addition, the “filler” as used in the specification of the present application is a component that does not constitute a polymer system constituting the cured body, and has low compatibility with the polymer system, so that it does not dissolve in the polymer system. The one that is only physically dispersed.

  The photosensitive resin composition of the present invention is a photosensitive resin composition containing a base polymer (A), a photopolymerizable ethylenically unsaturated bond-containing compound (B), and a photopolymerization initiator (C). A phosphorus-containing ethylenically unsaturated compound (B1) is included as the ethylenically unsaturated bond-containing compound (B).

  As the base polymer (A) in the present invention, a conventional polymer used in a photosensitive resin composition can be used, and in particular, a carboxyl group-containing (meth) acrylic suitable as a base polymer for a resist dry film. A polymer mainly composed of a polymer is preferably used.

  As such a carboxyl group-containing (meth) acrylic polymer, a carboxyl group-containing polymer (A1) having a weight average molecular weight of 100,000 to 250,000 and an acid value of 50 to 250 mgKOH / g (hereinafter referred to as “high molecular weight carboxyl”). Group-containing polymer (A1) ”), and a carboxyl group-containing (meth) acrylic polymer (A2) having a weight average molecular weight of 5,000 to 80,000 and an acid value of 50 to 300 mgKOH / g ) (Hereinafter sometimes abbreviated as “medium molecular weight carboxyl group-containing polymer (A2)”) is preferably used.

  Since the carboxyl group-containing (meth) acrylic polymer can form a three-dimensional cross-linked cured body when used in combination with a thermal cross-linking agent described later, more excellent heat resistance and solvent resistance can be imparted. And as a carboxyl group containing (meth) acrylic-type polymer, a high molecular weight carboxyl group containing polymer (A1) is excellent in a moldability, and can provide flexibility. On the other hand, high molecular weight carboxyl group-containing polymer (A1) alone is difficult to obtain compatibility with other components and tends to deteriorate developability, but should be used in combination with medium molecular weight carboxyl group-containing polymer (A2). Thus, it is possible to provide followability to the circuit board and developability.

  Examples of the high molecular weight carboxyl group-containing polymer (A1) include a copolymer of (meth) acrylic acid and (meth) acrylic acid ester, more preferably (meth) acrylic acid and (meth) acrylic acid ester. And a copolymer of styrene. Among these copolymers, in the case of a homopolymer, a copolymer containing (meth) acrylic acid ester, methyl methacrylate, and methacrylic acid having a glass transition temperature (Tg) of 20 ° C. or lower is preferable. A copolymer obtained by copolymerizing these copolymer components and a copolymer component containing styrene is particularly preferable. In the case of a homopolymer, by adding a (meth) acrylate unit having a glass transition temperature (Tg) of 20 ° C. or less, flexibility and followability to a conductor circuit can be imparted, and a methyl methacrylate unit is contained. Therefore, transparency and developability can be imparted.

  Examples of the (meth) acrylic acid ester used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( Aliphatic (meth) acrylates having 1 to 20, preferably 1 to 10 carbon atoms of alkyl groups such as meth) acrylate and cyclohexyl (meth) acrylate; aromatic (meth) acrylates such as benzyl (meth) acrylate; dimethylamino Amino group-containing (meth) acrylates such as ethyl (meth) acrylate; hydroxyl-containing (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; epoxy groups containing glycidyl (meth) acrylate (meta Acrylate, and the like. These may be used in combination either alone or in combination.

  Among the above (meth) acrylic acid esters, (meth) acrylic acid esters having a glass transition temperature (Tg) of 20 ° C. or lower in the case of homopolymers include methyl acrylate, ethyl acrylate, n-butyl (meth) acrylate, i -Butyl acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate and the like.

  The weight average molecular weight (Mw) of the high molecular weight carboxyl group-containing polymer (A1) is preferably 100,000 to 250,000, more preferably 120,000 to 200,000. If the weight average molecular weight (Mw) is too small, flexibility tends to be inferior, while if it is too large, developability tends to decrease and resolution tends to decrease, or residues tend to appear after development. .

  The acid value of the high molecular weight carboxyl group-containing polymer (A1) is preferably 50 to 250 mgKOH / g, and more preferably 120 to 240 mgKOH / g. This is because if the acid value is too low, the resist developability tends to be insufficient, and if it is too high, the fine line adhesion of the resist pattern tends to be poor.

  As the medium molecular weight carboxyl group-containing polymer (A2), for example, a copolymer of (meth) acrylic acid and (meth) acrylic acid ester, a copolymer of styrene, (meth) acrylic acid and (meth) acrylic acid ester , A copolymer of styrene and (meth) acrylic acid, and the like. Among them, a copolymer of styrene, (meth) acrylic acid and (meth) acrylic acid ester, and a copolymer of styrene and (meth) acrylic acid. Preferably used.

  As the (meth) acrylic acid ester constituting the medium molecular weight carboxyl group-containing polymer (A2), monomers similar to those constituting the high molecular weight carboxyl group-containing polymer (A1), that is, methyl (meth) acrylate, ethyl ( The alkyl group such as (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate has 1 to 20 carbon atoms, preferably 1 Aliphatic (meth) acrylate of -10; aromatic (meth) acrylate such as benzyl (meth) acrylate; amino group-containing (meth) acrylate such as dimethylaminoethyl (meth) acrylate; hydroxyethyl (meth) acrylate, hydroxyp Pill (meth) hydroxyl group-containing acrylates such as (meth) acrylate; glycidyl (meth) acrylate, can be used in conjunction alone or.

  The weight average molecular weight (Mw) of the medium molecular weight carboxyl group-containing polymer (A2) is preferably 5,000 to 80,000, more preferably 10,000 to 70,000. If the weight average molecular weight (Mw) is too small, the flexibility tends to be inferior. If it is too large, the followability to the conductor circuit is poor, or the compatibility with the high molecular weight carboxyl group-containing polymer (A1) is poor. This is because the smoothness of the resist pattern tends to be inferior, or the surface smoothness after embedding in the conductor circuit tends to be inferior.

  The acid value of the medium molecular weight carboxyl group-containing polymer (A2) is preferably 50 to 300 mgKOH / g, more preferably 120 to 280 mgKOH / g. If the acid value is too low, the resist developability tends to be inferior, and if it is too high, the compatibility with the high molecular weight carboxyl group-containing polymer (A1) becomes poor, and the smoothness of the resist pattern tends to be inferior. This is because there is a tendency to have poor adhesion.

  The combined ratio of the high molecular weight carboxyl group-containing polymer (A1) and the medium molecular weight carboxyl group-containing polymer (A2) is set in the range of (A1) / (A2) = 20/80 to 75/25 in weight ratio. More preferably, it is in the range of (A1) / (A2) = 30/70 to 65/35, more preferably (A1) / (A2) = 40/60 to 60/40, particularly preferably It is in the range of 50/50 to 60/40. When it is out of the range of the combined use ratio, it tends to be inferior in chemical resistance or in conformity to the conductor circuit.

  When a mixed polymer of a high molecular weight carboxyl group-containing polymer (A1) and a medium molecular weight carboxyl group-containing polymer (A2) is used as the base polymer (A), each polymer is not limited to one type, but two or more types of high polymers A combination of a molecular weight carboxyl group-containing polymer (A1) and two or more kinds of medium molecular weight carboxyl group-containing polymers (A2) may be used. The polymer component (A) is not limited to a blend of the high molecular weight carboxyl group-containing polymer (A1) and the medium molecular weight carboxyl group-containing polymer (A2). A carboxyl group-containing (meth) acrylic polymer having a weight average molecular weight of about 50,000 to 250,000 may be used.

The content of the base polymer (A) is preferably set in the range of 15 to 45% by weight of the entire photosensitive resin composition excluding the solvent, and more preferably 20 to 40% from the viewpoint of followability to the conductor circuit. %. If the content is too small, the embedding property of the photosensitive resin composition between the conductor circuits tends to be good, but the content of the ethylenically unsaturated bond-containing compound (B) to be relatively photopolymerized is increased. When the photosensitive resin composition is used as a dry film, the stickiness of the photosensitive resin layer tends to increase. This is because air tends to enter easily when laminating to a conductor circuit, and it tends to be wrinkled when the photosensitive resin laminate is stored in a roll shape, and the photosensitive resin composition layer from the end face. Tends to ooze out, which is inconvenient for storage, and tends to be broken without securing sufficient strength for tenting the through hole.
Even when the resist is used as a liquid resist, the resist is too soft and the resist flows during coating, and it tends to be difficult to sufficiently form the insulating layer on the wiring. Furthermore, regardless of whether it is a dry film or a liquid resist, there is a tendency that solder heat resistance, solvent resistance, alkali resistance, etc. are reduced.

  Conversely, when the content of the base polymer (A) is increased and the content of the ethylenically unsaturated bond-containing compound (B) is relatively decreased, the stickiness can be eliminated, but the substrate and the photosensitive resin composition There is a tendency that voids are easily formed between them, making it difficult to ensure sufficient insulation, or that the photosensitive resin layer is easily peeled off from the substrate due to the voids. Further, it tends to be inferior in developability and flexibility.

  The ethylenically unsaturated bond-containing compound (B) includes a compound containing phosphorus in the molecule, that is, a phosphorus-containing ethylenically unsaturated compound (B1). The phosphorus-containing ethylenically unsaturated compound (B1) is preferably a polyester oligomer (a) obtained by polycondensation of a polyvalent carboxylic acid, a polyhydric alcohol, and a phosphorus compound having an ester-forming functional group; Alternatively, a reaction product with an ethylenically unsaturated compound (b) having a carboxyl group is used.

  Although it does not specifically limit as said polyvalent carboxylic acid, For example, the polyvalent carboxylic acid which two or more carboxyl groups couple | bond with the C2-C10 alkyl or aryl group is used, and an alkyl group is linear. Type or branch type. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, terephthalic acid, sebacic acid, decanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, tetrahydrophthalic acid Dicarboxylic acids such as acid, tetrachlorophthalic acid, hexahydrophthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid; trimesic acid, hemimellitic acid, trimellitic acid, pyro Examples include melicic acid, tricarboxylic acid such as 1,2,4-butanetricarboxylic acid, and 1,2,5-hexatricarboxylic acid.

  Although it does not specifically limit as said polyhydric alcohol, For example, the polyol which couple | bonds two or more hydroxyl groups with a C2-C10 alkyl group or an aryl group is used, and an alkyl group is linear or branched type. Good. Specifically, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, pinacol, 1,8-octanediol, 1 , 9-nonanediol, 1,10-decanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl -1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl Diols such as -1,3-pentanediol and 2-methyl-1,6-hexanediol; glycerin, trimethylolethane, trimethylolpropane Glycerol, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentane triol, such triol such as 1,2,6-hexanetriol is used.

  The phosphorus compound having an ester-forming functional group is a compound having a hydroxyl group capable of forming an ester, a carboxyl group, or an ester atomic group capable of transesterification, and having a phosphorus atom. The phosphine oxide represented by (1), the phosphinic acid ester represented by General formula (2), and the phosphonic acid ester represented by General formula (3) are mentioned.

In the general formulas (1) to (3), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrocarbon group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, An alkyl group such as a propyl group; an aryl group such as a phenyl group and a tosyl group; In the formula (1), R ¹ and R ² may form a ring by bonding. In the formula (2), R ¹ and R ³ may form a ring, and the formula (3) , R ³ and R ⁴ may form a ring with each other. In the formula, A is an ester-forming functional organic group represented by the following general formula (4).

In General Formula (4), R ⁵ is an ester-forming functional group, and specifically, for example, a hydroxyl group, a carboxyl group, or an ester atomic group. X is a trivalent organic group, for example, a dicarboxylic acid residue such as 2-methylpropanedioic acid residue or terephthalic acid residue having R ⁵ as a carboxyl group, or methyl having R ⁵ as a hydroxyl group. Examples thereof include diol residues such as propanediol residue, hydroquinone residue and bis (hydroxymethyl) phenyl ether residue.

Examples of the phosphorus compound having such an ester-forming functional group include those represented by the following formulas (5) to (8).

  By mixing the polyhydric carboxylic acid, polyhydric alcohol, and phosphorus compound having an ester-forming functional group at a molar ratio suitable for ester formation and polycondensing, the terminal is a hydroxyl group, a carboxyl group or an ester. A polyester oligomer (a) having ester atom groups capable of exchange reaction is obtained.

  Examples of the ethylenically unsaturated compound (b) having a hydroxyl group and / or a carboxyl group include unsaturated alcohols such as allyl alcohol, crotyl alcohol, and oleyl alcohol, and unsaturated acids such as acrylic acid, methacrylic acid, vinyl acetic acid, and crotonic acid. Although saturated carboxylic acid is used, Preferably it is C3-C10, Furthermore, the C4-C8 unsaturated monocarboxylic acid or unsaturated monoalcohol is used suitably.

  The phosphorus-containing ethylenically unsaturated compound (B1) used in the present invention is a reaction product of the polyester oligomer (a) and the ethylenically unsaturated compound (b), preferably 1 to 1 phosphorus atom per molecule. It is a polyester oligomer having 5, especially 1 to 3, and having a terminal ethylenically unsaturated bond. When a trivalent or higher polyvalent carboxylic acid or polyol such as tricarboxylic acid or triol is used as a raw material for the polyester oligomer (a), it may contain a free carboxyl group and / or hydroxyl group.

  The number average molecular weight of such phosphorus-containing ethylenically unsaturated compound (B1) is preferably 800 to 2000, particularly 1000 to 1500, and the phosphorus atom content in the compound is 1 to 10% by weight. In particular, the content is preferably 3 to 8% by weight. If the number average molecular weight is too small, the surface tack tends to be large, and if it is too large, the developability and the circuit following property tend to be poor. Moreover, when the content rate of a phosphorus atom is too small, there exists a tendency for it to be inferior in a flame retardance, and when too large, there exists a tendency for phosphorus containing ethylenically unsaturated compound (B1) itself to become unstable.

  Specifically, dicarboxylic acids having 4 to 6 carbon atoms such as succinic acid and adipic acid, diols having 3 to 6 carbon atoms such as 1,6-hexanediol, and phosphine as shown in the general formula (6). Phosphorus containing an ethylenically unsaturated bond at the terminal of a polyester oligomer containing 5 to 20 ester bond units obtained by polycondensation of phosphinic acid ester as shown in oxide or general formula (7) An ethylenically unsaturated compound is more preferably used. Examples of such phosphorus-containing ethylenically unsaturated compounds include Raylock (trade name) manufactured by Daicel Cytec.

  Such a phosphorus-containing ethylenically unsaturated compound (B1) has little stickiness in the composition state, and can be vacuum laminated as a resist dry film without adding an inorganic filler for eliminating stickiness to the composition. Can be satisfied. Moreover, since such a phosphorus containing ethylenically unsaturated compound (B1) can produce | generate the polymer in which the phosphorus atom was taken in by photopolymerization, it is made to contain inorganic fillers, such as a flame retardant added conventionally. Even if not, flame retardancy can be satisfied. Therefore, it is possible to provide solder resists with excellent cleanliness that can withstand ultrasonic cleaning in addition to the characteristics required for solder resists, that is, flexibility and insulation, as resists used for HDD suspension circuit boards. To.

  The phosphorus-containing ethylenically unsaturated compound (B1) is preferably contained within a range of 5 to 50% by weight, more preferably 15 to 45% by weight, based on the total weight of the photosensitive resin composition excluding the solvent. Furthermore, 20 to 40 weight% is preferable. If the content is too small, there is a tendency that the effect of reducing the tackiness of the resin composition cannot be obtained. If the content is too large, the content of the base polymer is relatively reduced, so that the phosphorus-containing ethylenically unsaturated compound (B1) There is a tendency that the vacuum laminating property when a dry film is formed cannot be satisfied only by the stickiness reducing effect due to the addition of.

  Further, the phosphorus-containing ethylenically unsaturated compound (B1) is preferably contained in a range where the content with respect to the ethylenically unsaturated bond-containing compound (B) is 10 to 70% by weight, more preferably 20 to 60% by weight. %, More preferably 30 to 50% by weight. If the content is too small, the effect of reducing the surface tack tends to be not obtained, and if the content is too large, the chemical resistance and the solder heat resistance tend to be inferior.

  As the photopolymerizable ethylenically unsaturated bond-containing compound (B), in addition to the phosphorus-containing ethylenically unsaturated compound (B1), an epoxy (meth) acrylate compound containing two or more hydroxyl groups in one molecule It is preferable to contain (B2) (hereinafter sometimes abbreviated as “epoxy (meth) acrylate monomer (B2)”). By combining the epoxy (meth) acrylate monomer (B2) as the ethylenically unsaturated bond-containing compound (B), it reacts with a carboxyl group in the base polymer or a thermal crosslinking agent described later by heat treatment to form a bond. Can be formed. Thereby, a crosslinking density can be raised and more excellent heat resistance and solvent resistance can be provided.

  As the epoxy (meth) acrylate monomer (B2), bisphenol A-modified epoxy (meth) acrylate is preferably used from the viewpoint of heat resistance. As such a bisphenol A-modified type epoxy (meth) acrylate, specifically, “Ebecryl” series 600 series made by Daicel Cytec Co., Ltd., 645,648, 3412,3500, 3700 series 3701, etc. Examples include EA-1020, 1025, 1026, 1028 manufactured by Shin-Nakamura Chemical Co., Ltd. These compounds are used alone or in combination of two or more.

  In addition to the phosphorus-containing ethylenically unsaturated compound (B1) and the epoxy (meth) acrylate monomer (B2), the ethylenically unsaturated bond-containing compound (B) further has another ethylenically unsaturated group (meth). An acrylic monomer may be used. The other acrylic monomer is not particularly limited, but it is preferable to use a bifunctional or higher polyfunctional compound in consideration of heat resistance, solvent resistance, and chemical resistance. Specifically, urethane (meth) acrylate compounds, trimethylolpropane tripropoxy tri (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol Di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexane glycol di (meth) acrylate Glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, die Lenglycol diglycidyl ether di (meth) acrylate, diglycidyl phthalate di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, 1,6-hexamethyl Diglycidyl ether di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerin polyglycidyl ether poly (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol hexa (meth) acrylate, 2,2′-bis (4- (meth) acryloxydiethoxyphenyl) propane, 2,2 ′ -Bis (4- (meth) acryloxypentaethoxyphenyl) propane, 2,2'-bis (4- (meth) acryloxypolyethoxyphenyl) propane, 2-hydroxy-3- (meth) acryloyloxypropyl acrylate, Examples thereof include polyfunctional monomers such as trimethylolpropane triglycidyl ether tri (meth) acrylate. In addition, an appropriate amount of a monofunctional monomer can be used in combination with the polyfunctional monomer. Examples of such a monofunctional monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Hydroxybutyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2- (meth) acryloyloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth) acrylate, glycerin mono ( Examples include meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, phthalic acid derivative half (meth) acrylate, and N-methylol (meth) acrylamide. These may be used alone or in combination of two or more.

  The total content of the ethylenically unsaturated bond-containing compound (B) is preferably 15 to 75% by weight, more preferably 25 to 65% by weight, based on the entire photosensitive resin composition excluding the solvent. . If the content of the ethylenically unsaturated bond-containing compound (B) in the entire photosensitive resin composition is too small, the resolution, sensitivity, and developability tend to be inferior, and the crosslinking density after curing is not sufficient. Heat resistance, solvent resistance, and chemical resistance tend to be inferior, and if too much, the photosensitive resin composition layer becomes too sticky. It tends to be inconvenient for storage, such as being easy to enter, and being prone to wrinkling when stored in roll form.

  As a photoinitiator (C) used with the said base polymer (A) and an ethylenically unsaturated bond containing compound (B), it does not specifically limit and a conventionally well-known thing is used. For example, benzoin ether, benzyl ketals, acetophenones, benzophenones, thioxanthones (2-isopropylthioxanthone, 2-ethylthioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, etc.), quinones, 2-methyl-1 -[4- (Methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2- (dimethylamino) -4-morpholinobutylphenone, 9-phenylacridine and the like. These may be used alone or in combination of two or more. Among these, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 9-phenylacridine, 2,4-diethylthioxanthone, benzyldimethyl ketal, 2,4- Diethylthioxanthone is preferred, particularly 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 9-phenylacridine and 2,4-diethylthioxanthone, A combination of methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzyldimethyl ketal and 2,4-diethylthioxanthone is preferred.

  It is preferable to make content of the said photoinitiator (C) into 0.5 to 15 weight% of the whole photosensitive resin composition except a solvent, More preferably, it is 1 to 10 weight%. If the amount is too small, the sensitivity becomes insufficient, and there is a tendency that the above-mentioned ethylenically unsaturated bond-containing compound (B) is not sufficiently cured. Conversely, if the amount is too large, defects such as poor resolution are observed. This is because there is a tendency.

  The photosensitive resin composition of the present invention preferably further contains a thermal crosslinking agent (D) in order to enhance chemical resistance and heat resistance. As the thermal crosslinking agent (D), the base polymer (A) It is preferable to use a compound having good compatibility with the ethylenically unsaturated bond-containing compound (B), and specifically it is preferable to contain the blocked isocyanate compound (D1).

  The blocked isocyanate compound used in the present invention is one in which two or more isocyanate groups which are active groups exist in the isocyanate prepolymer molecule, each of which is stabilized by masking with phenol, oxime, etc. Or an oxime can be eliminated to expose an isocyanate group and react with a hydroxyl group or a carboxyl group in the polymer to form a three-dimensional crosslinked structure. That is, it can act as a thermal crosslinking agent by activation of the isocyanate group. Examples of such blocked isocyanate compounds include Duranate manufactured by Asahi Kasei Chemicals, Takenate manufactured by Takeshi Mitsui Chemicals, and the like.

  Therefore, when a carboxyl group-containing (meth) acrylic polymer is used as the base polymer (A), the carboxyl group-containing (meth) acrylic polymer and the blocked isocyanate compound (D1) react by heat treatment. Thus, since a three-dimensional crosslinked structure can be formed, a cured product having excellent heat resistance and solvent resistance can be obtained. Moreover, the reactive group which exists in the polymer produced | generated by photopolymerization of the ethylenically unsaturated bond containing compound (B), for example, the epoxy group derived from an epoxy (meth) acrylate type monomer (B2), a hydroxyl group, phosphorus containing ethylene When the unsaturated compound (B1) has a free hydroxyl group or carboxyl group, it can react with the hydroxyl group or carboxyl group to form a three-dimensional crosslinked structure. Examples of the thermal crosslinking agent (D) include melamine resins in addition to the above-mentioned blocked isocyanate compound (D1).

  The content of the thermal crosslinking agent (D) is appropriately determined depending on the type and content of the base polymer (A), the structure and content of the ethylenically unsaturated bond-containing compound (B), and the type of the thermal crosslinking agent (D). Although it is determined, when the blocked isocyanate compound (D1) is used, its content is preferably 1 to 10% by weight of the entire photosensitive resin composition excluding the solvent, more preferably 3 to 7%. % By weight. When the content is too small, chemical resistance and heat resistance tend to be lost, and when the content is too large, flexibility tends to be inferior.

  In the photosensitive resin composition of the present invention, when it is desired to impart high flame retardancy, a phosphorus compound (E) containing at least four phenoxy groups in one molecule (hereinafter referred to as “ (It may be described as “phosphorus compound (E)”). However, in the resin composition of the present invention, the polymer formed by photopolymerization of the phosphorus-containing ethylenically unsaturated compound (B1) can also serve as a flame retardant, and therefore does not contain the phosphorus compound (E). However, the necessary flame retardancy (V-0 evaluation level in the flame retardancy test) can be ensured.

  Substituents other than oxygen may be bonded to the benzene ring in the phenoxy group bonded to the phosphorus compound (E). Examples of such phosphorus compounds (E) include phosphate ester compounds and phosphazene compounds. As the phosphoric acid ester compound, aromatic condensed phosphoric acid esters are preferably used. As the phosphazene compound, a compound having a 3- to 7-membered ring structure of bis (phenoxy) phosphazene, poly [bis (phenoxy) phosphazene] Etc. are preferably used. These phosphate ester compounds and phosphazene compounds are used alone or in combination of two or more.

  The photosensitive resin composition of the present invention may further include a pigment, a dye, an antioxidant, an adhesion promoter, a light absorber, a leveling agent, a flame retardant other than the phosphorus compound (E), and a filler as necessary. Other additives (F) such as an antifoaming agent can be appropriately blended.

  However, when the resin composition of the present invention is used for a circuit board for HDD suspension, a filler that does not become a part of the polymer cured body, or a polymer cured body, in order to satisfy a high cleanliness requirement by ultrasonic cleaning. Since the compatibility is not good, it is preferable not to contain a three-dimensional cross-linked structure of the polymer cured body and a filler that is highly likely not to be taken into the polymer island.

  Even if the resin composition of the present invention is a non-filler, flame retardancy can be ensured as described above, and characteristics required for a solder resist for HDD suspension, that is, sensitivity, resolution, developability, flexibility Solder heat resistance, solvent resistance, electrical migration resistance, circuit followability, and vacuum laminating properties can be satisfied.

  The photosensitive resin composition of the present invention is added to the base polymer (A), the ethylenically unsaturated bond-containing compound (B), the photopolymerization initiator (C), the thermal cross-linking agent (D) as necessary. It can prepare by mix | blending and mixing additives (E and / or F), such as a phosphorus compound. And when producing the below-mentioned photosensitive resin laminated body, an organic solvent is mixed and used so that it may become a predetermined density | concentration.

  Examples of the organic solvent include, but are not limited to, acetone, methyl ethyl ketone, methanol, isopropyl alcohol, propylene glycol monoethyl ether, ethyl acetate, butyl acetate, and the like. These may be used alone or in combination of two or more. Used. And as the density | concentration, although suitably set according to the construction method applied at the time of preparation of the below-mentioned photosensitive resin laminated body, and a viscosity, it is the range of 35 to 60 weight% of solid content normally.

  The photosensitive resin composition of the present invention having the above-described configuration may be used as an ink (liquid resist) applied to a circuit board as it is, or because it is excellent in vacuum laminating properties, and therefore suitable as a dry film resist. Can be used. It is also useful as a flexible printed wiring board (FPC) coverlay and solder resist, and is also used in the manufacture of lead frames and the like, and precision metal processing. In particular, the resin composition of the present invention has excellent heat resistance, and can satisfy the characteristics required for a permanent protective film of a circuit board such as electric migration resistance and circuit followability. Useful.

  The dry film resist formed using the photosensitive resin composition of the present invention may be a single film, or may form the photosensitive resin composition layer of the present invention on a support film (carrier film), Furthermore, you may use as the photosensitive resin laminated body which laminated | stacked the protective film (cover film).

  The support film is not particularly limited as long as it is transparent and flexible and can withstand coating drying. For example, a polyester film such as a polyethylene terephthalate (PET) film, or a stretched polypropylene (OPP) ) A film etc. are mentioned, Preferably it is a PET film.

  The protective film has a role to prevent transfer of the photosensitive resin composition layer having adhesiveness to the support film when the photosensitive resin laminate is rolled, for example, a polyethylene (PE) film, A polyolefin film such as a polypropylene (PP) film, a PET film, a fluororesin (PTFE) film, a polyvinyl alcohol film, a nylon film, or the like is used, and a polyolefin film, particularly a PE film is preferably used. Since the composition layer formed using the photosensitive resin composition of this invention is excellent in vacuum laminating property, the surface roughness of the protective film for ensuring the surface roughness of the composition layer is not particularly limited. In particular, the surface roughness of the protective film can provide more reliable and excellent vacuum laminating properties by using a protective film having an average roughness (Ra) of 1 or more. In addition, the said surface average roughness (Ra) is an average height which remove | divided the area of the roughness curve by the measurement length, as shown by JISB06011994.

  In the photosensitive resin laminate of the present invention, for example, the photosensitive resin composition of the present invention is uniformly coated on one surface of the support film, and then dried to form a photosensitive resin composition layer. It can produce by laminating | stacking a protective film.

  In the photosensitive resin laminate of the present invention, the thickness of the photosensitive resin composition layer varies depending on the thickness of the copper wiring, but is usually preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 20 to 60 μm. If the photosensitive resin composition layer is too thick, curing by pattern exposure tends to be insufficient at the lower part of the resist, so that there is a tendency that poor adhesion occurs or it is difficult to obtain sufficient resolution.

  The thickness of the support film is preferably 10 to 25 μm. If the thickness of the film is too thin, the resistance of the photosensitive resin laminate itself is inferior, and the support film tends to be broken when peeled off, and if it is too thick, the support film becomes hard, due to its hardness. There is a tendency that the followability of the photosensitive resin composition layer to the conductor circuit is inferior. Moreover, the thickness of a protective film is 10-50 micrometers normally, Preferably it is 15-35 micrometers.

Next, the manufacturing method of the flexible printed wiring board at the time of using the photosensitive resin laminated body of the said this invention as a soldering resist dry film is demonstrated below.
〔laminate〕
The protective film of the photosensitive resin laminate is peeled off, and the surface of the photosensitive resin composition layer is bonded to a wiring surface of a substrate on which a conductor circuit such as FPC is formed using a laminator. A vacuum laminator is preferably used from the viewpoint of followability to a conductor circuit, and the photosensitive resin composition layer of the laminate of the present invention can be neatly laminated without involving air or the like.

〔exposure〕
Next, the pattern mask is directly contacted (adhered) on the support film on the opposite side of the photosensitive resin composition layer and exposed. In the case of proximity exposure and projection exposure, the pattern mask is exposed in a non-contact state. Furthermore, direct imaging (direct exposure) using a laser may be performed without using a pattern mask. The exposure is usually performed by ultraviolet (UV) irradiation, and as a light source at that time, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, an argon laser, or the like is used.

〔developing〕
After the exposure, the support film on the photosensitive resin composition layer is peeled off, and then the unexposed portion (uncured portion) is dissolved and dispersed by development. When the photosensitive resin composition is a dilute alkali development type, a dilute aqueous solution having an alkali concentration of about 0.3 to 2% by weight such as sodium carbonate or potassium carbonate is used as the developer. In the development, a method of spraying at a uniform pressure is preferable from the viewpoint of resolution and adhesion stability. In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be mixed. And after development, it is sufficiently washed with water and dried. By developing, the unexposed resist portion is dissolved to expose the lower copper pattern portion that requires plating or soldering.

[Heat cure]
In order to further enhance characteristics such as surface curability, solder heat resistance, and chemical resistance, a further crosslinking reaction step is performed. The cross-linking reaction step that becomes heat curing is usually performed at 150 to 180 ° C. for about 30 to 120 minutes.
Before heat curing, UV curing (post-exposure) may be performed after sufficiently drying after development in order to improve characteristics such as surface curability, solder heat resistance, and chemical resistance. UV cure is usually used at 0.5 to ¹⁰ J / cm ² .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded. In the following examples, “parts” and “%” mean weight basis unless otherwise specified.

[Measurement evaluation method]
First, measurement evaluation methods performed in the following examples and comparative examples will be described.
(1) Sensitivity PE film that has been satin-finished as a protective film (average surface roughness when measuring 10.0 mm in the transverse direction (TD direction) of the film roll with a contact tip of 2 μmR and a measurement load of 0.07 gf) Ra = 1.51), the protective film of the photosensitive resin composition laminate produced by the method described later is peeled off, and the photosensitive resin composition layer is applied to a polyimide film having a thickness of 25 μm and a copper foil having a thickness of 18 μm. The FPC copper-clad polyimide film for FPC (size 150 mm x 150 mm) is placed on a copper foil surface and temporarily attached, and a diaphragm-type vacuum laminating machine (Nichigo Morton, “V-130”) is attached. It was laminated under the conditions of a decompression time of 30 seconds, a platen temperature of 55 ° C., and a slap down of 8 seconds. This laminated product was allowed to stand at 20 ° C. for 2 hours, and a 21-step tablet made by Stouffer was in close contact with the PET film, exposed to a 2 kW mercury short arc lamp (parallel light), and then heated to 30 ° C. Spray development (spray pressure 0.15 MPa) was performed for 2 times the minimum development time with a 1% Na ₂ CO ₃ aqueous solution, followed by washing with water and drying. And the exposure amount when the numerical value of the step tablet in which the metal part has come out is 8 (8 steps) was displayed as sensitivity.

(2) Resolution The same photosensitive resin composition laminate as that used in the sensitivity measurement was prepared. In place of the Stouffer 21-step tablet, line / space = 20 μm / 20 μm to 120 μm / 120 μm pattern mask (silver salt-PET film) was used in the same manner as in the sensitivity measurement, and copper for FPC was used. A photosensitive resin composition layer was bonded to a stretched polyimide film, and the 2 kW ultra-high pressure mercury short arc lamp (parallel light) was irradiated with an exposure amount equivalent to 8 steps of a 21-step tablet made by Stouffer and developed. At this time, the value of the minimum line width indicating the resolution (the value of the minimum width (μm) between the cured lines formed by development) was defined as the resolution.

(3) Developability A copper substrate (FR-4, thickness 1.6 mm) was prepared, the copper foil surface was subjected to buffalo polishing (after # 600, # 1000), washed with water, and then washed with 10% sulfuric acid at room temperature (25 (° C.) for 1 minute, washed with water, dried and allowed to stand at room temperature for 24 hours. The protective film of the photosensitive resin laminate is peeled off, and the photosensitive resin composition layer (thickness 30 μm) is used on the copper substrate using a diaphragm type vacuum laminating machine (Nichigo Morton, “V-130”), Lamination was performed in the same manner as in the sensitivity measurement. The photosensitive resin laminate used here has a size of 100 mm × 100 mm having the photosensitive resin composition layer having a thickness of 30 μm. After leaving unexposed at 20 ° C. for 20 minutes, spray development (spray pressure 0.15 MPa) for 2 times the minimum development time with a 1 wt% Na ₂ CO ₃ aqueous solution at 30 ° C., washing with water and drying. . After that, immerse it again in water at 25 ° C., lean it on the rack at an angle of about 85 °, measure the degree of water repelling on the surface of the substrate leaning on the rack with a stopwatch, and develop it by repelling water. Evaluated. That is, the degree of development residue (organic residue) on the copper substrate was determined by a water repellency test as follows.
A: Does not repel water for 15 seconds or longer (good developability).
○ ... Repels water in 10 seconds or more and less than 15 seconds.
X: Water is repelled in less than 10 seconds (there is an organic residue).

(4) Flexibility The protective film of the photosensitive resin laminate is peeled off, and the photosensitive resin composition layer (thickness 30 μm) is subjected to a diaphragm type vacuum laminating machine (Nichigo Morton, “V” as in the sensitivity measurement). -130 ") and laminated on both sides of a polyimide film having a thickness of 25 µm under the same conditions. Next, the entire surface was irradiated with an exposure amount equivalent to 8 steps of a 21-step tablet made by Stouffer with the 2 kW ultra-high pressure mercury short arc lamp (parallel light), and UV cure 3 J / cm ² (made by International Light, “ IL-390A "was measured on both sides, followed by heat curing at 180 ° C for 60 minutes to prepare a cured film. And the same location of this cured film was operated as a mountain fold to a valley fold to a mountain fold (folding radius 0 °), and the flexibility was evaluated as follows. The bending was performed in a room at 23 ° C. × 50% RH.
A: No cracking was observed even after 10 or more operations.
○: Cracked in 6 to 9 operations.
Δ: Cracked in 2 to 5 operations.
X: Cracked in one operation.

(5) Vacuum laminating property Using a photosensitive resin composition laminate formed using a PE film that has not been satin-finished as a protective film, the vacuum is applied to the copper-clad polyimide film for FPC according to the evaluation of the sensitivity. Lamination was performed using a laminating machine. The slap down time was changed to 15 seconds, the platen temperature was laminated at 65 ° C., 55 ° C., and 45 ° C., and the presence or absence of air entrainment at each temperature was observed and evaluated according to the following criteria.
A: Air is not caught even at 65 ° C (good).
○ Air is entrained at 65 ° C, but not at 55 ° C.
Δ: Air is entrained at 55 ° C, but not at 45 ° C.
X: Air is involved even at 45 ° C.

(6) Followability to conductor circuit Except that the thickness of the photosensitive resin composition layer was changed to 25 μm, the same photosensitive resin composition laminate as that used for sensitivity measurement was the same as that during the sensitivity measurement. Then, a copper-clad polyimide film having a copper thickness of 35 μm was laminated and laminated on a substrate in which copper wiring of IPC-B25A (IPC standard) was formed, and exposed at 150 mJ / cm ² . The substrate surface when the temperature at the time of vacuum lamination was changed to 50 ° C., 55 ° C., and 65 ° C. was observed with a microscope, and the followability to the conductor circuit was evaluated as follows.
A: The conductor circuit was completely followed at 50 ° C., and there was no gap between the photosensitive resin composition layer and the conductor circuit.
○: The conductor circuit was not completely followed at 50 ° C., but the conductor circuit was completely followed at 55 ° C., and there was no void between the photosensitive resin composition layer and the conductor circuit.
Δ: The conductor circuit was not completely followed at 55 ° C., but the conductor circuit was completely followed at 65 ° C., and there was no gap between the photosensitive resin composition layer and the conductor circuit.
X: The conductor circuit was not completely followed even at 65 ° C.

(7) Solder heat resistance A photosensitive resin composition laminate similar to that used in the sensitivity measurement was prepared. A photosensitive resin composition layer was bonded to a substrate on which a copper wiring of IPC-B25A (IPC standard) was formed using a copper-clad polyimide film having a copper thickness of 18 μm in the same manner as in the sensitivity measurement. Next, using a pattern mask to which the D pattern terminals of this circuit can be soldered, the above-described 2 kW ultra-high pressure mercury short arc lamp (parallel light) is irradiated with an exposure amount equivalent to 8 steps of a 21-step tablet made by Stouffer. Development and drying were performed. Subsequently, UV curing of ³ J / cm ² was performed using a transport UV exposure machine “model UVCS 923” (measurement value of “IL-390A” manufactured by International Light). The substrate temperature at this time was 120 ° C. Thereafter, heat curing was performed at 160 ° C. for 60 minutes to produce a flexible printed wiring board (FPC) on which a coverlay made of a photosensitive resin composition layer was formed.

After applying “Flux ULF-500VS” manufactured by Tamura Kaken Co., Ltd. on the surface of the produced FPC, drying was performed at 100 ° C. for 1 minute, and soldering treatment at 260 ° C. was performed for 10 seconds. When this flux application to soldering operation is repeated a total of three times, the coverlay cracking state, the D pattern solder flaking state, and the swollenness state are visually observed and combined to ensure solder heat resistance. Evaluation was performed as follows.
◎ ... No cracks, solder flaking, or blistering was observed in all three times.
○: There was no problem in both cases, but some solder peeling was confirmed in the third time.
Δ: Slight soldering was confirmed at the second time, and swelling occurred at the third time.
X: The soldering operation could not be already performed in the first time.

(8) Chemical resistance Substrate prepared according to the above solder heat resistance measurement is immersed in a 10% NaOH aqueous solution at 40 ° C. for 15 minutes and then immersed in water, and the state of occurrence of resist floating and peeling of the substrate is observed. In addition, the peelability of the resist by rubbing the wet resist with Kimwipe was confirmed and evaluated according to the following criteria.
◎ ・ ・ ・ No floating or peeling, no problem with Kimwipe.
○: No floating or peeling occurred, but it was damaged by Kimwipe.
X: Floating or peeling occurred.

(9) Electrical migration resistance An electrical migration test of IPC-SM-840C3.9.1 (IPC standard) was performed using the substrate prepared according to the evaluation of the solder heat resistance. That is, using the D pattern, the resistance after 168 hours was examined at 85 ° C. × 90% RH for 168 hours, 10 VDC bias potential, and 45-100 VDC test potential, and the electrical insulation was evaluated as follows. According to the standard, 2 MΩ or more is accepted.
A: Over 200 MΩ, no dendride was observed even under microscopic observation.
○: It exceeded 200 MΩ, but what seemed to be dendrid was observed with a microscope.
Δ: 2 to 200 MΩ.
X: Less than 2 MΩ.

(10) Flame retardant FR-4 [A copper-clad laminate (CEL475SD manufactured by Shin-Kobe Electric Co., Ltd.) having a thickness of 0.3 mm is etched on both sides] After pasting in the same manner as in the measurement, both surfaces were exposed at 150 mJ / cm ² (ORC “UV-351” integrating actinometer). Subsequently, the inside of the developing tank of 1% Na ₂ CO ₃ aqueous solution at 30 ° C. was passed at 0.15 MPa in a pass time of 25 seconds, and sufficiently washed and dried. Thereafter, using a model UVCS 923, double-sided UV curing was performed at 3 J / cm ² (measured with “IL-390A” manufactured by International Light), and then heat curing (160 ° C. × 60 minutes) was performed. An evaluation substrate was prepared.

  The produced substrate was cut into a length of 125 ± 5 mm and a width of 13.0 mm ± 0.5 mm, and conformed to UL-94, a flame retardant test standard for polymer materials of US Underwriters Laboratories Inc. (hereinafter referred to as “UL”). Therefore, a vertical flammability test was performed. In accordance with this standard, the flame retardancy evaluation was expressed as V-0, V-1, V-2, and NOT-V from those having good flame retardancy.

[Preparation of photosensitive resin composition and production of laminate]
Photosensitive resin composition No. 1:
In accordance with the composition shown in Table 1, the composition No. 1 was dissolved in a solvent (methyl ethyl ketone: isopropanol = 75: 25 [weight ratio]) to prepare a photosensitive resin composition solution having a concentration of 55%. The prepared photosensitive resin composition solution was uniformly coated on a 19 μm-thick PET film (support film) using an applicator, allowed to stand at room temperature for 1 minute and 30 seconds, and then dried in an oven at 130 ° C. for 3 minutes. Thus, a photosensitive resin composition layer having a thickness of 30 μm was formed. Next, a PE film (protective film) having a thickness of 30 μm is laminated on the photosensitive resin composition layer at 30 ° C. and 0.2 MPa, and the photosensitive resin having the photosensitive resin composition layer having a thickness of 30 μm. A laminate was prepared and evaluated according to the above-described measurement evaluation method using the prepared laminate.

Photosensitive resin composition No. 2-8:
Composition No. As shown in Table 2, the base polymer (A), the ethylenically unsaturated bond-containing compound (B), the photopolymerization initiator (C), the thermal crosslinking agent (D), or the additive (E or F) in 1 Composition No. changed 2-8 were prepared and composition No. Evaluation was performed in the same manner as in 1.
That is, the composition No. 2 used A2-b instead of the medium molecular weight carboxyl group-containing polymer A2-a.
Composition No. 3 changed the kind of blocked isocyanate compound from D1 to D2.
Composition No. 4 reduced the amount of phosphorus-containing ethylenically unsaturated compound (B1) and added phosphorus compound (E1) as a flame retardant.
Composition No. 5 reduced the amount of phosphorus-containing ethylenically unsaturated compound (B1) and added phosphorus compound (E2) as a flame retardant.
Composition No. 6 increased the content of the ethylenically unsaturated bond-containing compound (B3) without containing the phosphorus-containing ethylenically unsaturated compound (B1).
Composition No. 7 increased the contents of the ethylenically unsaturated bond-containing compounds (B2) and (B3) without containing the phosphorus-containing ethylenically unsaturated compound (B1).
Composition No. 8 is a high molecular weight carboxyl group-containing polymer (A1), a medium molecular weight carboxyl group-containing polymer A2-a, and an ethylenically unsaturated bond-containing compound (B2) without containing the phosphorus-containing ethylenically unsaturated compound (B1). , (B3) content was increased.

The evaluation results are collectively shown in Table 2. In addition, each component shown in Table 1 and Table 2 is as follows.
(1) High molecular weight carboxyl group-containing polymer (A1)
Carboxyl group-containing polymer polymerized at a ratio of methyl methacrylate / n-butyl methacrylate / styrene / methacrylic acid = 45/15/15/25 (weight ratio) (weight average molecular weight Mw = 168,000, acid value 163 mgKOH / g ). The weight average molecular weight Mw is a value obtained by measuring a THF (tetrahydrofuran) solution of a dry polymer on a polystyrene basis using a GPC (gel permeation chromatography) apparatus.
(2) Medium molecular weight carboxyl group-containing polymer (A2)
(2-1) A2-a:
Carboxyl group-containing polymer polymerized at a ratio of methyl methacrylate / styrene / 2-ethylhexyl acrylate / methacrylic acid = 31/30/15/24 (weight ratio) (weight average molecular weight Mw = 45,000, acid value 156 mgKOH / g )
(2-2) A2-b:
Carboxyl group-containing polymer obtained by polymerization at a ratio of styrene / acrylic acid = 75/25 (weight ratio) (weight average molecular weight Mw = 20,000, acid value 195 mgKOH / g)

(3) Compound containing ethylenically unsaturated bond (B)
B1: “RAYLOCK 1722” manufactured by Daicel Cytec Co., Ltd. (This is a phosphorus-containing ethylenically unsaturated compound using a phosphorus compound having an ester-forming functional group as shown in the above formula (7). From C-NMR (Zgig) (The calculated number average molecular weight is 1200 and the phosphorus content is 4.5%.)
B2: “Ebecryl 648” manufactured by Daicel Cytec Co., Ltd. (This is a bisphenol A epoxy acrylate containing two or more OH groups in one molecule.)
B3: Ethylene oxide modified bisphenol A diacrylate (Number of ethylene oxide repeats: 10)
B4: “SR492” manufactured by Sartomer (this is trimethylolpropane tripropoxytriacrylate)

(4) Photopolymerization initiator (C)
C1: “Irgacure 907” manufactured by Ciba (this is 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one)
C2: “Irgacure 651” manufactured by Ciba (this is benzyldimethyl ketal)
C3: 2,4-diethylthioxanthone

(5) The following blocked isocyanate as the thermal crosslinking agent (D) D1: “Duranate TPA-B80E” manufactured by Asahi Kasei Chemicals Corporation
D2: “Takenate B-882N” manufactured by Mitsui Takeda Chemical Co., Ltd.

(6) Additive E1: Bisphenol A bis (diphenyl) phosphate E2: Bisphenol A bis (dicresyl phosphate)
F: “Modaflow” manufactured by Surface Specialties

As can be seen from Table 2, when the phosphorus-containing ethylenically unsaturated compound (B1) is not contained (No. 6, 7), the vacuum laminating property is poor and the flexibility is poor, and the flame retardant (E1 ) Or (E2) was not added, the flame retardancy could not be satisfied. No. As can be seen from FIG. 8, by increasing the content of the base polymer, the stickiness can be reduced and the vacuum laminating property can be satisfied, but if the epoxy (meth) acrylate monomer (B2) increases, the developability is increased. In addition, by not containing the phosphorus-containing ethylenically unsaturated compound (B1), flexibility was lowered and flame retardancy could not be satisfied.
On the other hand, when the phosphorus-containing ethylenically unsaturated compound (B1) is contained as an ethylenically unsaturated bond-containing compound, stickiness is suppressed and excellent vacuum laminating properties are obtained (No. 1 to 5), and the flame retardant (E1 ) And (E2) were able to satisfy flame retardancy regardless of the presence or absence (No. 1 to 3).

  The photosensitive resin composition of the present invention can satisfy the flame retardancy without containing an inorganic filler such as a flame retardant or fumed silica, and can satisfy the vacuum laminating property by suppressing stickiness. It can satisfy the characteristics required for solder resists such as solvent resistance, flame retardancy, flexibility, followability to conductor circuits, developability, solder heat resistance, etc., so high cleanliness is required It can be used as a solder resist dry film used for a circuit board for HDD suspension or a photosensitive resin composition capable of providing the dry film.

Claims (11)

In the photosensitive resin composition comprising the base polymer (A), the photopolymerizable ethylenically unsaturated bond-containing compound (B), and the photopolymerization initiator (C),
The ethylenically unsaturated bond-containing compound (B) comprises a phosphorus-containing ethylenically unsaturated compound (B1) and an epoxy ((meth) acrylate compound (B2) having two or more hydroxyl groups in the molecule,
The phosphorus-containing ethylenically unsaturated compound (B1) is
A polyester oligomer (a) obtained by polycondensation of a polyvalent carboxylic acid, a polyhydric alcohol, and a phosphorus compound having an ester-forming functional group;
A photosensitive resin composition which is a reaction product with an ethylenically unsaturated compound (b) having a hydroxyl group and / or a carboxyl group . The photosensitive resin composition according to claim 1 , wherein the phosphorus compound having an ester-forming functional group is a compound represented by any one of the following general formulas (1) to (3).

^(Wherein, R 1 to R ⁴ are each a hydrocarbon group having 1 to 20 carbon atoms, which may be the same or different and also ^{R 1} and ^R 2, ^{R 1} and ^R 3, ^{R 3} And R ⁴ may form a ring with each other, and A has a structure represented by the following general formula (4).

(In the formula, X is a trivalent organic group, and R ⁵ is an ester-forming functional group.) 3. The photosensitive property according to claim 1, wherein the phosphorus-containing ethylenically unsaturated compound (B1) has a number average molecular weight of 800 to 2000 and a phosphorus atom content in the molecule of 1 to 10% by weight. Resin composition. The photosensitive resin composition according to any one of claims 1 to 3 , wherein a content of the phosphorus-containing ethylenically unsaturated compound (B1) with respect to the total weight of the photosensitive resin composition excluding the solvent is 5 to 50% by weight. . The photosensitive resin composition according to any one of claims 1 to 4 , wherein a content of the phosphorus-containing ethylenically unsaturated compound (B1) with respect to the ethylenically unsaturated bond-containing compound (B) is 10 to 70% by weight. . The base polymer (A) has a carboxyl group (meth) photosensitive resin composition according to any one of claims 1 to 5 which is a polymer consisting mainly of acrylic polymer. The (meth) acrylic polymer having the carboxyl group is
A (meth) acrylic polymer (A1) having a carboxyl group having a weight average molecular weight of 100,000 to 250,000 and an acid value of 50 to 250 mgKOH / g;
The photosensitive resin according to claim 6 , which is a mixture with a (meth) acrylic polymer (A2) having a carboxyl group having a weight average molecular weight of 5,000 to 80,000 and an acid value of 50 to 300 mgKOH / g. Composition. The photosensitive resin composition according to claim 6 , wherein the content of the base polymer (A) with respect to the total weight of the photosensitive resin composition excluding the solvent is 15 to 45% by weight. Furthermore, the photosensitive resin composition in any one of Claims 1-8 containing a blocked isocyanate type compound (D1). Support film;
And a photosensitive resin laminate comprising a protective film laminated to the photosensitive resin composition layer; the photosensitive resin composition layer according to any one of claims 1 to 9 which is laminated on the support film. The photosensitive resin laminate according to claim 10 , wherein the photosensitive resin composition layer contains substantially no filler.