JP5935462B2 - Photosensitive element, resist pattern forming method, printed wiring board manufacturing method - Google Patents

Description

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

  In recent years, semiconductor packages such as BGA (Ball Grid Array) used for mounting an IC chip on a substrate are becoming more and more pinned and narrowed as the trend toward lighter, thinner and smaller semiconductor devices is increasing. The printed wiring board on which these are mounted is also required to have a high density.

  Conventionally, in the field of production of printed wiring boards, as a resist material used for etching, plating, etc., a support film, a photosensitive resin composition layer composed of a photosensitive resin composition laminated on the support film, and this A photosensitive element comprising a protective film for covering the film is widely used.

  A printed wiring board is manufactured by the method shown below using a photosensitive element. First, the photosensitive resin composition layer is laminated (laminated) on the substrate while peeling off the protective film of the photosensitive element. Next, a predetermined part of the photosensitive resin composition layer is irradiated with actinic rays to cure the exposed part. After the support film is peeled and removed, the unexposed portion is removed (developed) from the substrate, whereby a resist pattern made of a cured product of the photosensitive resin composition is formed on the substrate. A printed wiring board is manufactured by subjecting the substrate on which the resist pattern is formed to an etching process or a plating process to form a circuit on the substrate, and finally removing and removing the resist.

  In particular, in manufacturing a semiconductor package mounting substrate, a semi-additive method (SAP) in which plating processing, resist peeling, and soft etching are performed after forming a resist pattern has become mainstream.

  The photosensitive resin composition used for the semi-additive construction method (SAP) is required to be capable of forming finer wiring than the conventional photosensitive resin composition.

  Conventionally, a large number of photosensitive resin compositions capable of forming fine wiring (excellent in resolution and adhesion) have been proposed (see, for example, Patent Documents 1 to 3).

JP-A-2005-301101 JP 2006-234959 A JP 2006-154740 A

  However, even when the photosensitive resin composition described in Patent Document 1 or 2 is used, there is room for improvement in the resolution required in recent years. In addition, when the photosensitive resin composition described in Patent Document 3 is used by the study of the present inventors, in the plating step when forming the resist pattern, the resistance to the plating solution at the end of the resist (hereinafter referred to as the resist pattern) It was found that there was room for improvement in that the plating resistance was reduced and the plating was peeled off.

  As a technique for improving the plating resistance, a technique for imparting a hydrophobic compound to the resist and a technique for improving the glass transition temperature are generally used. However, in these methods, there is a problem that development scum is generated due to hydrophobicity improvement, resist peeling residue adherence occurs, resist flexibility is lowered due to an increase in glass transition temperature, and plating removal is not improved. The present inventors have found that.

  In addition, the present inventors tried a technique for improving resist flexibility by imparting a hydrophilic compound to the resist. However, the adhesion of the resist and the plating resistance are reduced, and fine wiring required for SAP It was difficult to produce a photosensitive resin composition that can be formed and has excellent plating resistance.

  The present invention has been made in view of the above problems, a photosensitive resin composition having excellent resolution and adhesion, and good plating resistance, a photosensitive element using the same, a method for producing a resist pattern, and It aims at providing the manufacturing method of a printed wiring board.

  A first aspect of the present invention is a photosensitive resin composition comprising (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator, (A) component is (a1) 50-80 mass% of structural units derived from benzyl (meth) acrylate derivative, (a2) 5-40 mass% of structural units derived from styrene derivative, (a3) (meth) acrylic acid It is a photosensitive resin composition containing 1 to 20% by mass of a structural unit derived from an alkyl ester and 5 to 30% by mass of a structural unit derived from (a4) (meth) acrylic acid.

  According to such a photosensitive resin composition, the resolution and adhesion are excellent, and the plating resistance is good. The present inventors speculate that this is because the binder polymer contains a specific amount of a specific copolymerization component, thereby providing a resist having an excellent balance between hydrophilicity and hydrophobicity.

  2nd aspect of this invention is a photosensitive element provided with a support film and the photosensitive resin composition layer which consists of the said photosensitive resin composition formed on this support film.

  The third aspect of the present invention is a lamination step of laminating a photosensitive resin composition layer comprising the photosensitive resin composition on a substrate, and an exposure step of forming a photocured portion on the photosensitive resin composition layer. And a developing step for removing the photosensitive resin composition layer other than the photocured portion. This aspect may be an aspect in which the photosensitive resin composition layer is laminated using a photosensitive element.

  According to a fourth aspect of the present invention, there is provided a printed wiring board manufacturing method in which an etching process or a plating process is performed on a substrate on which a resist pattern is formed by the resist pattern forming method.

  INDUSTRIAL APPLICABILITY According to the present invention, a photosensitive resin composition having excellent resolution and adhesion and excellent plating resistance even on a thin plate substrate, a photosensitive element using the same, a method for producing a resist pattern, and a method for producing a printed wiring board Can be provided.

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

  Hereinafter, although one embodiment of the present invention is described, the present invention is not limited to this. In the present invention, (meth) acrylic acid means acrylic acid and methacrylic acid, (meth) acrylate means acrylate and the corresponding methacrylate, and (meth) acryloyl group means acryloyl group and methacryloyl group. means.

(Photosensitive resin composition)
The photosensitive resin composition of the present embodiment includes (A) a binder polymer (hereinafter also referred to as “(A) component”), (B) a photopolymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as “(B ) Component ”) and (C) a photopolymerization initiator (hereinafter also referred to as“ component (C) ”). Hereinafter, the components (A) to (C) will be described in detail.

  First, (A) the binder polymer will be described. The (A) binder polymer functions as a base material for imparting a film shape to the photosensitive element described later.

  The (A) binder polymer comprises (a1) a structural unit derived from a benzyl (meth) acrylate derivative, (a2) a structural unit derived from a styrene derivative, (a3) a structural unit derived from a (meth) acrylic acid alkyl ester, and (a4 ) Containing structural units derived from (meth) acrylic acid. The binder polymer containing these structural units is a monomer containing a monomer corresponding to each structural unit, that is, a benzyl (meth) acrylate derivative, a styrene derivative, a (meth) acrylic acid alkyl ester, and a (meth) acrylic acid. It is obtained by copolymerizing the monomer composition. In the copolymer thus obtained, each structural unit may be randomly contained in the copolymer such as a so-called random copolymer, or some specific unit such as a block copolymer. It may be a copolymer in which structural units exist in a localized manner. And each of the said structural unit may be single type, or multiple types.

  (A) A binder polymer is excellent in adhesiveness, maintaining the softness | flexibility of resin by including the specific amount of the structural unit derived from (a1) benzyl (meth) acrylate derivative. Specific examples of the benzyl (meth) acrylate derivative include, for example, benzyl (meth) acrylate, 4-methylbenzyl (meth) acrylate, 4-ethylbenzyl (meth) acrylate, 4-tertbutylbenzyl (meth) acrylate, 4-methoxy Examples include benzyl (meth) acrylate, 4-ethoxybenzyl (meth) acrylate, 4-hydroxylbenzyl (meth) acrylate, and 4-chlorobenzyl (meth) acrylate.

  (A) A binder polymer is excellent in the adhesiveness and resolution of a thin wire | line part by including the specific amount of the structural unit derived from (a2) styrene derivative. Specific examples of the styrene derivative include styrene, vinyltoluene, p-methylstyrene, and p-chlorostyrene.

(A) The binder polymer is excellent in both flexibility and toughness of the binder polymer by including a specific amount of the structural unit derived from (a3) (meth) acrylic acid alkyl ester.
The alkyl group in the (meth) acrylic acid alkyl ester is preferably a linear or branched alkyl group having 1 to 12 carbon atoms, and is a linear or branched alkyl group having 1 to 8 carbon atoms. More preferably, it is a linear alkyl group having 1 to 4 carbon atoms, more preferably a methyl group.

  Specific examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, Examples include tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

  (A) The binder polymer is excellent in alkali developability by containing a specific amount of a structural unit derived from (a4) (meth) acrylic acid.

  The (A) binder polymer may contain structural units other than the above (a1) to (a4).

  (A) The binder polymer contains 50 to 80% by mass of the structural unit derived from (a1) benzyl (meth) acrylate derivative, and 50 to 75% by mass in terms of better adhesion while maintaining the flexibility of the resin. Is preferable, it is more preferable to contain 50-70 mass%, and it is more preferable to include 50-65 mass%.

  (A) The binder polymer preferably contains 5 to 35% by mass of (a2) a structural unit derived from a styrene derivative and is further excellent in adhesion and resolution. In addition, (a3) the structural unit derived from (meth) acrylic acid alkyl ester is contained in an amount of 1 to 20% by mass, but it is preferably contained in an amount of 1 to 15% by mass in terms of providing the resist with a more balanced hydrophilicity and hydrophobicity. It is more preferable to contain 1-10 mass%, and it is still more preferable to contain 1-5 mass%. Furthermore, it contains 5 to 30% by mass of the structural unit derived from (a4) (meth) acrylic acid, but it is preferably 5 to 25% by mass and more preferably 10 to 25% by mass in terms of further excellent alkali developability. More preferred.

  The weight average molecular weight (Mw) of the (A) binder polymer is preferably 20,000 to 150,000, more preferably 30,000 to 100,000, and 40,000 to 80,000. More preferably, it is particularly preferably 40,000 to 60,000. In terms of further excellent tent reliability, Mw is preferably 20,000 or more, more preferably 30,000 or more, and further preferably 40,000 or more. On the other hand, in terms of further excellent developability and resolution, it is preferably 150,000 or less, more preferably 100,000 or less, further preferably 80,000 or less, and 60,000 or less. It is particularly preferred that In the present invention, Mw refers to a weight average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC).

  The acid value (mgKOH / g) of the (A) binder polymer is preferably 13 to 78, more preferably 39 to 65, and still more preferably 52 to 62. In addition, in this specification, an acid value represents the mg number of potassium hydroxide with respect to 1g of binder polymers in a solution, and the measuring method is made the same as the method as described in an Example.

  In addition, the photosensitive resin composition of this embodiment can be used in combination with a conventionally known binder polymer in addition to the binder polymer containing a predetermined amount of the above (a1) to (a4).

  (B) The photopolymerizable compound having an ethylenically unsaturated bond can be used without particular limitation as long as photocrosslinking is possible. Specific examples thereof include bisphenol A (meth) acrylate compounds, hydrogenated bisphenol A (meth) acrylate compounds, polyalkylene glycol (meth) acrylates, urethane monomers, pentaerythritol (meth) acrylates, and trimethylolpropane (meth). An acrylate is mentioned. These are used alone or in combination of two or more.

  Among these, from the viewpoint of improving resolution and plating resistance, it is preferable to include a bisphenol A di (meth) acrylate compound. Examples of the bisphenol A-based di (meth) acrylate compound include compounds represented by the following general formula (1).

In said formula (1), R shows a hydrogen atom or a methyl group each independently. EO and PO represent an oxyethylene group and an oxypropylene group, respectively. m ₁ , m ₂ , n ₁ and n ₂ each represent 0 to 40, m ₁ + m ₂ (average value) is 1 to 40, and n ₁ + n ₂ is 0 to 20. Either EO or PO may be on the phenolic hydroxyl group side. m ₁ , m ₂ , n ₁ and n ₂ represent the number of structural units. Therefore, an integer value is shown in a single molecule, and a rational number that is an average value is shown as an aggregate of a plurality of types of molecules. Hereinafter, the same applies to the number of structural units.

From the viewpoint of excellent by plating resistance, in the compounds represented by the above general formula (1), the compound is _(1-1) m 1 + _{m 2} (average value) is 5 or less, _(1-2) m 1 + _{m 2} It is preferable to use a combination of compounds having an (average value) of 6 to 40.

(1-1) As a compound whose m ₁ + m ₂ (average value) is 5 or less, for example, BPE-200 manufactured by Shin-Nakamura Chemical Co., Ltd. whose m ₁ + m ₂ (average value) is 4 can be used. (1-2) As a compound whose m ₁ + m ₂ (average value) is 6 to 40, for example, BPE-500 manufactured by Shin-Nakamura Chemical Co., Ltd. whose m ₁ + m ₂ (average value) is 10 is used. Can do.

  Moreover, it is preferable that the (B) photopolymerizable compound which has an ethylenically unsaturated bond further contains the compound represented by following formula (2) in addition to the bisphenol A di (meth) acrylate compound.

上記式（２）中、Ｒ^１４及びＲ^１５はそれぞれ独立に水素原子又はメチル基を示し、ＥＯ及びＰＯは上記と同義であり、ｓ^１は１〜３０を示し、ｒ^１及びｒ^２はそれぞれ０〜３０を示し、ｒ^１＋ｒ^２（平均値）は１〜３０である。

In the above formula ^{(2), R 14} and ^{R 15} each independently represent a hydrogen atom or a methyl group, EO and PO are as defined above, ^{s 1} represents a 1 to 30, ^{r 1} and ^{r 2} are each It indicates ^{0~30, r} 1 + r ² (average value) is 1 to 30.

Specific examples of the compound represented by the formula (2) include vinyl compounds in which R ¹⁴ and R ¹⁵ are methyl groups, r ¹ + r ² = 4 (average value), and s ¹ = 12 (average value) (Hitachi Chemical) (Trade name: FA-023M, manufactured by Kogyo Co., Ltd.).

  (C) The photopolymerization initiator can be used without particular limitation. Specific examples thereof include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl- 4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- [4- Aromatic ketones such as (methylthio) phenyl] -2-morpholino-propanone-1; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benz Anthraquinone, 2-phenylanthraquinone, 2,3-diphenyla Quinones such as traquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenantharaquinone, 2-methyl 1,4-naphthoquinone, 2,3-dimethylanthraquinone; benzoin methyl ether, Benzoin ether compounds such as benzoin ethyl ether and benzoin phenyl ether, benzoin compounds such as benzoin, methyl benzoin and ethyl benzoin; benzyl derivatives such as benzyldimethyl ketal, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-di 2,4,5-triarylimidazole dimers such as phenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer; 9-phenylacridine, 1,7-bis ( Acridine derivatives such as 9,9′-acridinyl) heptane, N-phenylglycine, N-phenylglycine derivatives, and coumarin compounds. These are used alone or in combination of two or more.

  Among the above, from the viewpoint of adhesion and sensitivity, 2,4,5-triarylimidazole dimer, more preferably 2- (O-chlorophenyl) -4,5-diphenylimidazole dimer is preferably included. .

  The content of the (A) binder polymer in the photosensitive resin composition is preferably 40 to 80 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B), and 45 to 75 parts by mass. It is more preferable that it is 50-70 mass parts. When used as a photosensitive element, it is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, and still more preferably 50 parts by mass or more in terms of further excellent coating properties. Moreover, in the point which is further excellent in a photosensitivity, it is preferable that it is 80 mass parts or less, It is more preferable that it is 75 mass parts or less, It is further more preferable that it is 70 mass parts or less.

  The content of the photopolymerization initiator (C) in the photosensitive resin composition is 0.01 with respect to 100 parts by mass of the total amount of the component (A) and the component (B) in terms of excellent photosensitivity and internal curability. It is preferable that it is -5 mass parts, It is more preferable that it is 0.1-4.5 mass parts, It is more preferable that it is 1-4 mass parts.

  If necessary, the photosensitive resin composition may include a photopolymerizable compound having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, a sensitizer, a dye such as malachite green, tribromo, and the like. Photochromic agents such as methylphenylsulfone and leucocrystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion promoters, leveling agents Additives such as a peeling accelerator, an antioxidant, a fragrance, an imaging agent, and a thermal crosslinking agent may be added. When these additives are added to the photosensitive resin composition, the content thereof is about 0.01 to 20 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B). it can. These may be used alone or in combination of two or more.

  The total content of the components (A), (B) and (C) in the photosensitive resin composition is preferably 90% by mass or more with respect to the total solid content of the photosensitive resin composition, and is 95% by mass. % Or more is more preferable.

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

  The photosensitive resin composition is not particularly limited, but is coated as a liquid resist on a metal surface such as copper, a copper-based alloy, iron, or an iron-based alloy, dried, and then covered with a protective film as necessary. It is preferably used in the form of a photosensitive element.

(Photosensitive element)
Hereinafter, the photosensitive element of this embodiment is demonstrated based on FIG. The photosensitive element 1 of this embodiment includes a support film 10 and a photosensitive resin composition layer 20 made of the above-described photosensitive resin composition. The photosensitive resin composition layer 20 is provided on the first main surface 12 of the support film 10. The support film 10 has a second main surface 14 on the side opposite to the first main surface 12. Moreover, the protective film may be provided in the surface on the opposite side to the support film 10 of the photosensitive resin composition layer 20. As shown in FIG. The photosensitive resin composition layer is one in which the photosensitive resin composition is in an uncured state.

  Although the thickness of the photosensitive resin composition layer 20 changes with uses, it is preferable that it is about 1-100 micrometers by the thickness after drying. In terms of use in the semi-additive construction method (SAP), the thickness is preferably 5 to 50 μm, and more preferably 5 to 30 μm.

  The support film 10 may be made of a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester. The thickness of these polymer films is preferably 1 to 100 μm.

  The photosensitive resin composition layer 20 can be obtained by applying and drying the above-described photosensitive resin composition on the support film 10. The application can be performed by a known method such as a roll coater, a comma coater, a gravure coater, an air knife coater, a die coater, or a bar coater. Moreover, drying can be performed at 70-150 degreeC and about 5 to 30 minutes.

  Moreover, the photosensitive element 1 may be provided with intermediate | middle layers and protective layers, such as a cushion layer, an adhesive layer, a light absorption layer, and a gas barrier layer other than the photosensitive resin composition layer 20, the support film 10, and a protective film. Good.

  The photosensitive element 1 is stored, for example, by being wound around a cylindrical core as it is or in a state in which the protective film is further laminated. At this time, it is preferable that the support film 10 is wound up so as to be on the outside. An end face separator is preferably installed on the end face of the roll-shaped photosensitive element roll from the viewpoint of end face protection, and a moisture-proof end face separator is preferably installed from the viewpoint of edge fusion resistance. Moreover, as a packing method, it is preferable to wrap and package in a black sheet with low moisture permeability.

(Method for forming resist pattern)
Examples of a method for forming a resist pattern using the photosensitive element 1 include the following methods.

When the protective film is present, after removing the protective film, the substrate is heated to about 0.1 to 1 MPa (about 1 to 10 kgf / cm ²⁾ while heating the photosensitive resin composition layer 20 to about 70 to 130 ° C. The photosensitive resin composition layer is laminated by pressure bonding at a pressure of). It is also possible to stack under reduced pressure. The surface to be laminated is usually a metal surface, but is not particularly limited.

  The photosensitive resin composition layer 20 thus laminated is irradiated with actinic rays in an image form through a negative or positive mask pattern. As the light source of the actinic light, a known light source, for example, a light source that effectively emits ultraviolet light, visible light, or the like such as a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, or a xenon lamp is used.

  As an exposure method, in recent years, a direct drawing exposure method called DLP (Digital Light Processing) or LDI (Laser Direct Imaging), which directly draws digital data of a pattern on a photosensitive resin composition layer, has been put into practical use. The photosensitive resin composition of this invention can be used suitably for a direct drawing exposure method. That is, the photosensitive resin composition of the embodiment of the present invention can be suitably used for a direct drawing exposure method. That is, one preferred embodiment of the present invention is a photosensitive resin composition containing (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator. The component (A) is 50 to 80% by mass of the structural unit derived from the (a1) benzyl (meth) acrylate derivative, (a2) 5 to 40% by mass of the structural unit derived from the styrene derivative, (a3 1) 20% by mass of a structural unit derived from (meth) acrylic acid alkyl ester, and 5-30% by mass of a structural unit derived from (a4) (meth) acrylic acid. This is an application for forming a resist pattern.

  After the exposure, when the support film 10 is present on the photosensitive resin composition layer, the support film 10 is removed, and then wet development or dry development with a developer such as an alkaline aqueous solution, an aqueous developer, or an organic solvent. The resist pattern can be formed by removing the unexposed part and developing the film.

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

As the treatment after development, the resist pattern may be further cured and used by heating at about 60 to 250 ° C. or exposure at about 0.2 to 10 J / cm ² as necessary. When manufacturing a printed wiring board using the photosensitive element of this embodiment, it processes by copper plating by using the developed resist pattern as a mask.

  Next, the resist pattern can be peeled with a stronger alkaline aqueous solution than the alkaline aqueous solution used for development, for example. As said strong alkaline aqueous solution, 1-10 weight% sodium hydroxide aqueous solution, 1-10 weight% potassium hydroxide aqueous solution, etc. are used, for example. Examples of the peeling method include an immersion method and a spray method.

(Printed wiring board manufacturing method)
The manufacturing method of the printed wiring board of this embodiment is performed by performing an etching process or a plating process with respect to the board | substrate with which the resist pattern was formed by the formation method of the said resist pattern. Here, the etching process or the plating process of the substrate is performed by etching or plating the surface of the substrate by a known method using the developed resist pattern as a mask.
Especially the photosensitive resin composition of this invention can be used suitably when forming a circuit on the base material for packages and the copper clad laminated board for flexible printed wiring boards by which thickness reduction is requested | required.

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

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

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

  The photosensitive resin composition of this embodiment can be used suitably for manufacture of a printed wiring board as mentioned above. That is, one preferred embodiment of the present invention is a photosensitive resin composition containing (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator. The component (A) is 50 to 80% by mass of the structural unit derived from the (a1) benzyl (meth) acrylate derivative, (a2) 5 to 40% by mass of the structural unit derived from the styrene derivative, (a3 ) A printed wiring board of a photosensitive resin composition containing 1 to 20% by mass of a structural unit derived from (meth) acrylic acid alkyl ester and 5 to 30% by mass of a structural unit derived from (a4) (meth) acrylic acid. Application to manufacturing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all.

(Examples 1-5 and Comparative Examples 1-4)
(Preparation of photosensitive resin composition solution)
(A) component shown in Table 1, (B) component, (C) component, the additive, and the solvent were mix | blended, and the photosensitive resin composition solution was obtained. In addition, the binder polymer in (A) component is obtained by the following method.

[Synthesis of binder polymer]
A solution obtained by dissolving 0.6 g of azobisisobutyronitrile in the polymerizable monomers (a1) to (a4) shown in Table 2 was designated as “Solution a”.

  A flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas introduction tube was charged with 100 g of a mixture of 60 g of methyl cellosolve and 40 g of toluene (mass ratio 3: 2), and nitrogen gas was introduced into the flask. The mixture was heated with stirring while being blown, and the temperature was raised to 80 ° C.

  After dropping the solution a over 4 hours into the mixed solution in the flask, the solution was dropped over 10 minutes while washing the dropping funnel with a mixed solution of 6 g of methyl cellosolve and 4 g of toluene (mass ratio 3: 2), The mixture was kept at 80 ° C. for 2 hours while stirring. Next, a solution obtained by dissolving 0.2 g of azobisisobutyronitrile in a mixed liquid of 6 g of methyl cellosolve and 4 g of toluene (mass ratio 3: 2) was dropped into the solution in the flask over 10 minutes, and then 18 g of methyl cellosolve was added. And 12 g of toluene (mass ratio 3: 2) was added dropwise over 10 minutes, and the solution in the flask was kept at 80 ° C. for 3 hours while stirring. Further, the solution in the flask was heated to 90 ° C. over 30 minutes, kept at 90 ° C. for 2 hours, and then cooled to obtain a solution of each binder polymer.

The weight average molecular weight was measured by gel permeation chromatography (GPC) and derived by conversion using a standard polystyrene calibration curve. The GPC conditions are shown below.
GPC condition pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd.)
Column: The following three Gelpack GL-R420
Gelpack GL-R430
Gelpack GL-R440 (above, manufactured by Hitachi Chemical Co., Ltd., trade name)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd.)

(Acid value measurement)
0.5 g of the binder polymer solution synthesized in the Erlenmeyer flask was weighed, dissolved by adding 30 ml of a mixed solvent (mass ratio: toluene / methanol = 70/30), added with a phenolphthalein solution as an indicator, and N / 10 water The acid value was measured by titration with a potassium oxide alcohol solution.

BPE-500: Bisphenol A dimethacrylate having an average of 10 moles of polyoxyethylene (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.)
BPE-200: Bisphenol A dimethacrylate having an average of 4 moles of polyoxyethylene (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.)
FA-023M: Dimethacrylate (trade name, manufactured by Hitachi Chemical Co., Ltd.) with an average of 3 mol of polyoxyethylene added to both ends of an average of 12 mol of polyoxypropylene

(Production of photosensitive element)
Next, the obtained photosensitive resin composition solution was uniformly applied onto a 16 μm-thick polyethylene terephthalate film (trade name “G2-16” manufactured by Teijin Limited), and a hot air convection dryer at 100 ° C. After drying for 10 minutes, the film was protected with a 28 μm thick polyethylene film (trade name “NF-15A” manufactured by Tamapoly Co., Ltd.) to obtain a photosensitive element. The film thickness after drying of the photosensitive resin composition layer was 15 μm.

(Formation of resist pattern)
Next, the copper surface of the copper-clad laminate for printed wiring boards (trade name “MCL-E679”, manufactured by Hitachi Chemical Co., Ltd.) is roughened, alkali degreased, acid washed, washed with water, and then dried in an air stream. The obtained substrate was heated to 80 ° C. The photosensitive resin composition layer was laminated on the copper surface at a speed of 1 m / min using a heat roll at 100 ° C. while peeling off the polyethylene film to obtain a laminate for evaluation.

<Evaluation of photosensitivity>
On the evaluation laminate, a 21-step stove tablet was adhered as a negative, and exposure was performed using an exposure machine (trade name “EXM-1201” manufactured by Oak Co., Ltd.) having a high-pressure mercury lamp lamp. Subsequently, the polyethylene terephthalate film was peeled off and sprayed with a 1% by weight sodium carbonate aqueous solution at 30 ° C. (spray (development) time: twice the minimum development time) to remove unexposed portions. Thereafter, the number of steps (X / 21) of the step tablet of the photocured film formed on the copper clad laminate was measured, and the exposure amount (mJ / cm ² ) indicating ST = 5/21 was defined as the value of the photosensitivity. . It shows that photosensitivity is so high that this figure is small.

<Evaluation of adhesion>
A glass phototool having a wiring pattern with a line width of 1 to 30 (unit: μm) as a negative is adhered to the evaluation laminate, and the number of remaining steps after development is ST = 5/21. The pattern was exposed. Subsequently, the polyethylene terephthalate film was peeled off and sprayed with a 1% by weight sodium carbonate aqueous solution at 30 ° C. (spray (development) time: twice the minimum development time) to remove unexposed portions. Then, it observed using the optical microscope and evaluated adhesiveness. The adhesion value is represented by the smallest value of the line width (μm) remaining without being peeled off by the development process, and the smaller this value, the higher the adhesion.

<Evaluation of resolution>
A glass phototool having a wiring pattern with a line width / space width of 1/1 to 30/30 (unit: μm) as a negative is brought into close contact with the evaluation laminate, and the number of remaining steps after development is ST = 5. Pattern exposure was performed with an energy amount of / 21. Subsequently, the polyethylene terephthalate film was peeled off and sprayed with a 1% by weight sodium carbonate aqueous solution at 30 ° C. (spray (development) time: twice the minimum development time) to remove unexposed portions. Then, it observed using the optical microscope and evaluated resolution. The value of the resolution is represented by the smallest value among the space widths (μm) in which the unexposed portions can be completely removed by the development processing, and the smaller the numerical value, the higher the resolution.

<Evaluation of plating resistance>
1 / 1-30 / 30 as a negative on a laminate for evaluation prepared by laminating a photosensitive resin composition layer on a copper-clad laminate for flexible printed wiring boards (trade name “F30VC1” manufactured by Nikkan Kogyo Co., Ltd.). A glass phototool having a wiring pattern of (unit: μm) was brought into close contact, and pattern exposure was performed with an energy amount such that the number of remaining steps after development was ST = 5/21. Next, the polyethylene terephthalate film was peeled off, and a 1 wt% aqueous sodium carbonate solution was sprayed at 30 ° C. (spray (development) time: twice the minimum development time) to remove the unexposed portion and obtain a substrate for evaluation. The substrate for evaluation was subjected to acid degreasing, water washing, and sulfuric acid dipping in this order, and copper plating treatment was performed using a copper sulfate plating solution until the plating thickness reached 12 μm under the condition of 1 A / dm ² . After washing with water and drying, the resist was peeled off, and the plating boring width was measured from above using an optical microscope. The value of the plating resistance is evaluated by the plating width, and the smaller the numerical value, the better the copper plating resistance.

<Flexibility>
The laminate for evaluation prepared by laminating the photosensitive resin composition layer on a copper-clad laminate for flexible printed wiring boards (product name “F30VC1” manufactured by Nikkan Kogyo Co., Ltd.) was cut into a 30 mm × 150 mm square size. The entire surface was exposed with an energy amount such that the number of remaining steps after development was ST = 5/21. Next, the polyethylene terephthalate film was peeled off and sprayed with a 1% by weight sodium carbonate aqueous solution at 30 ° C. (spray (development) time: twice the minimum development time). The maximum diameter at which the resist did not crack was measured with the Gardner mandrel bending tester. The smaller the diameter, the better the flexibility.

  As is apparent from Table 3, Examples 1 to 5 using the photosensitive resin composition of the present invention are excellent in flexibility and plating resistance, and exhibit sufficient photosensitivity, adhesion and resolution.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 10 ... Support film, 20 ... Photosensitive resin composition layer.

Claims (3)

A support film, a photosensitive element comprising a photosensitive resin composition layer composed of a photosensitive light-sensitive resin composition that will be formed on the support film,
The photosensitive resin composition contains (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator,
The component (A) includes (a1) 50 to 80% by mass of a structural unit derived from a benzyl (meth) acrylate derivative, (a2) 5 to 40% by mass of a structural unit derived from a styrene derivative, and (a3) (meth) acrylic. A photosensitive element comprising 1 to 20% by mass of a structural unit derived from an acid alkyl ester and 5 to 30% by mass of a structural unit derived from (a4) (meth) acrylic acid. A lamination step of laminating the photosensitive element according to claim 1 on the substrate in the order of the photosensitive resin composition layer and the support film;
An exposure step of forming a photocured portion in the photosensitive resin composition layer;
A developing step for removing the photosensitive resin composition layer other than the photocured portion;
A method for forming a resist pattern, comprising: A method for producing a printed wiring board, comprising subjecting a substrate on which a resist pattern is formed by the method for forming a resist pattern according to claim 2 , to etching or plating.

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