JP2006285133A - Photosensitive resin composition, photosensitive element, method for producing resist pattern and method for producing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition, having high sensitivity, superior resolution and adhesion, a photosensitive element that uses the same, a method for producing a resist pattern and a method for producing a printed wiring board. <P>SOLUTION: The photosensitive resin composition contains (A) a binder polymer, (B) an ethylenically unsaturated photopolymerizable monomer and (C) a photopolymerization initiator, wherein the maximum absorption wavelength, after irradiation of light on the photopolymerization initiator (C), shifts to a wavelength side shorter than the maximum absorption wavelength prior to exposure to light by ≥30 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Conventionally, in the field of manufacturing printed wiring boards, as a resist material used for etching and plating, a photosensitive resin composition and a photosensitive element obtained using a support and a protective film are widely used.
A printed wiring board is formed by laminating a photosensitive element on a copper substrate, pattern exposure, removing the unexposed portion with a developer, etching or plating, forming a pattern, and then curing the cured portion. It is manufactured by a method of peeling off from the substrate.
The photosensitive element is required to have higher resolution, higher adhesion, higher workability, and higher yield than conventional photosensitive elements as the density of printed wiring boards and the demand increase in recent years.
As a factor governing sensitivity, resolution, and adhesion, the absorbance of the photosensitive resin composition can be mentioned. In the conventional photosensitive element technology, improvement of resolution and adhesion has been realized by a binder polymer, a photopolymerizable monomer, a photopolymerization initiator, and the like, but it is still not sufficient. Further, for increasing the sensitivity, a method of increasing the absorbance is common, but there is a problem that the curability of the resist at the bottom is lowered and the adhesion is deteriorated.

JP 2004-4527 A JP 2002-323760 A

  An object of the present invention is to provide a photosensitive resin composition, a photosensitive element, a method for producing a resist pattern, and a method for producing a printed wiring board, which are highly sensitive and excellent in resolution and adhesion.

The present invention provides [1] a photosensitive resin composition having (A) a binder polymer, (B) an ethylenically unsaturated photopolymerizable monomer, and (C) a photopolymerization initiator. The present invention relates to a photosensitive resin composition characterized in that the maximum absorption wavelength after light irradiation is shifted to a lower wavelength side by 30 nm or more than the maximum absorption wavelength before light irradiation.
In addition, the present invention provides: [2] The photosensitive resin composition according to [1], wherein the (A) binder polymer includes at least (meth) acrylic acid and (meth) acrylic acid ester as a constituent monomer of a copolymerization component. About.
The present invention also relates to [3] the photosensitive resin composition as described in [1] or [2] above, wherein the (C) photopolymerization initiator has an oxime ester bond.
The present invention also relates to [4] a photosensitive element obtained by coating the photosensitive resin composition according to any one of [1] to [3] on a support and drying.
The present invention also provides [5] the photosensitive element according to the above [4], wherein the photosensitive resin composition layer is laminated on the circuit forming substrate, and irradiated with actinic rays in an image form, The present invention relates to a method for producing a resist pattern, wherein an exposed portion is photocured and an unexposed portion is removed by development.
Moreover, this invention relates to the manufacturing method of the printed wiring board characterized by etching or plating the circuit formation board | substrate with which the resist pattern was manufactured by the manufacturing method of the resist pattern as described in [6] said [5].

  The photosensitive resin composition of the present invention, the photosensitive element using the same, the method for producing a resist pattern, and the method for producing a printed wiring board have high sensitivity, excellent resolution and adhesion, and improve these.

Hereinafter, the present invention will be described in detail. In the present invention, (meth) acrylic acid means acrylic acid and methacrylic acid corresponding thereto, (meth) acrylate means acrylate and corresponding methacrylate, (meth) acryloyl group means acryloyl group and The corresponding methacryloyl group is meant.
The photosensitive resin composition of the present invention comprises (A) a binder polymer, (B) an ethylenically unsaturated photopolymerizable monomer, and (C) a photopolymerization initiator. The maximum absorption wavelength after light irradiation of the initiator is shifted to a lower wavelength side by 30 nm or more than the maximum absorption wavelength before light irradiation.

The (A) binder polymer can be produced, for example, by radical polymerization of a polymerizable monomer. Examples of the polymerizable monomer include styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, p-ethoxystyrene, p-chlorostyrene, and p-bromostyrene. Polymerizable styrene derivatives such as acrylamide, acrylonitrile, vinyl alcohol esters such as vinyl-n-butyl ether, (meth) acrylic acid alkyl ester, (meth) acrylic acid tetrahydrofurfuryl ester, (meth) acrylic acid dimethylamino Ethyl ester, (meth) acrylic acid diethylaminoethyl ester, (meth) acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, (Meta) Crylic acid, α-bromo (meth) acrylic acid, α-chloro (meth) acrylic acid, β-furyl (meth) acrylic acid, β-styryl (meth) acrylic acid, maleic acid, maleic anhydride, monomethyl maleate And maleic acid monoesters such as monoethyl maleate and monoisopropyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid and propiolic acid.
As said (meth) acrylic-acid alkylester, the compound etc. which the hydroxyl group, the epoxy group, the halogen group, etc. substituted the alkyl group of these compounds and the alkyl group of these compounds are mentioned, for example.

（一般式（Ｉ）中、Ｒ^１は水素原子又はメチル基を示し、Ｒ^２は炭素数１〜１２のアルキル基を示す）
上記一般式（Ｉ）中のＲ^２で示される炭素数１〜１２のアルキル基としては、例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基及びこれらの構造異性体が挙げられる。

(In general formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 12 carbon atoms)
Examples of the alkyl group having 1 to 12 carbon atoms represented by R ² in the general formula (I) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, Nonyl group, decyl group, undecyl group, dodecyl group and structural isomers thereof can be mentioned.

  Examples of the monomer represented by the general formula (I) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic. Examples include pentyl acid, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. These can be used alone or in combination of two or more.

The binder polymer (A) preferably contains a carboxyl group from the viewpoint of alkali developability, and is produced, for example, by radical polymerization of a polymerizable monomer having a carboxyl group and other polymerizable monomers. can do. As the polymerizable monomer having a carboxyl group, methacrylic acid is preferable. Further, the (A) binder polymer preferably contains styrene or a styrene derivative as a polymerizable monomer from the viewpoint of flexibility.
In order to make both the adhesiveness and the release property good by using the above styrene or styrene derivative as a copolymerization component, it is preferable to contain 2 to 30% by weight, more preferably 2 to 28% by weight, It is particularly preferable to include it. When the content is less than 2% by weight, the adhesion tends to be inferior, and when it exceeds 30% by weight, the peel piece tends to be large and the peel time tends to be long.

  These binder polymers are used alone or in combination of two or more. As a binder polymer in the case of using two or more types in combination, for example, two or more types of binder polymers comprising different copolymerization components, two or more types of binder polymers having different weight average molecular weights, and two or more types of binder polymers having different degrees of dispersion are used. Examples thereof include a binder polymer. In addition, a polymer having a multimode molecular weight distribution described in JP-A No. 11-327137 can be used.

  Examples of the (B) ethylenically unsaturated photopolymerizable monomer include a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid, 2,2-bis (4-((meth) acrylic). Loxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolypropoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolybutoxy) phenyl) propane, By reacting an α, β-unsaturated carboxylic acid with a bisphenol A-based (meth) acrylate compound such as 2,2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) propane or a glycidyl group-containing compound. Compound obtained, urethane monomer such as (meth) acrylate compound having urethane bond in molecule, nonylphenoxypolyethyleneoxy Phthalate compounds such as acrylate, γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxyalkyl-β ′-(meth) acryloyloxyalkyl-o-phthalate, (Meth) acrylic acid alkyl ester and the like can be mentioned, but a bisphenol A-based (meth) acrylate compound or a (meth) acrylate compound having a urethane bond in the molecule is preferably an essential component. These may be used alone or in combination of two or more.

  In the photosensitive resin composition having the (C) photopolymerization initiator, the maximum absorption wavelength after light irradiation of the (C) photopolymerization initiator is 30 nm or more lower than the maximum absorption wavelength before light irradiation. Examples of compounds that shift include compounds having oxime esters such as IRGACURE OXE01, PA-101 and NAI-105. Also, N, such as acridine or an acridine compound having at least one acridinyl group in the molecule, benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler's ketone) in combination with the photopolymerization initiator Quinones such as N′-tetraalkyl-4,4′-diaminobenzophenone and alkylanthraquinone, 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-diphenylimidazole dimer, 2 2,4,5-triphenyl such as-(p-methoxyphenyl) -4,5-diphenylimidazole dimer Reel imidazole dimer derivatives, N- phenylglycine, N- phenylglycine derivatives, coumarin-based compounds are used in combination, such as onium salts of two or more.

  The blending amount of the (A) binder polymer is preferably 40 to 80 parts by weight and more preferably 45 to 70 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B). preferable. If this blending amount is less than 40 parts by weight, the photocured product tends to be brittle, and when used as a photosensitive element, the coating properties tend to be inferior, and if it exceeds 80 parts by weight, the photosensitivity tends to be insufficient. .

  The blending amount of the (B) ethylenically unsaturated photopolymerizable monomer is preferably 20 to 60 parts by weight, and 30 to 55 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B). More preferably, it is a part. If this amount is less than 20 parts by weight, the photosensitivity tends to be insufficient, and if it exceeds 60 parts by weight, the photocured product tends to be brittle.

The blending amount of the photopolymerization initiator (C) is preferably a part by weight in which the absorbance of the photosensitive resin composition falls within the range of 0 to 2.0 before exposure (light irradiation), and further before exposure. It is still more preferable that the absorbance is within the range of 0.3 to 1.0. At this time, the absorbance after exposure is preferably less than the absorbance before exposure, and the absorbance after exposure is most preferably 0. However, the exposure amount in this case is 1 to 500 mJ / cm ² , and the wavelength of the irradiation light is in the range of 200 nm to 600 nm.
If the absorbance before exposure is less than 0.3, the photosensitivity becomes insufficient and the resolution tends to deteriorate. Further, since the light transmittance is too high, a halation effect is caused by the underlying copper substrate, and the bottom of the resist tends to be thick. On the other hand, if the absorbance before exposure exceeds 2.0, absorption at the surface of the composition during exposure tends to increase and internal photocuring tends to be insufficient.
On the other hand, if the absorbance after exposure is higher than that before exposure, the light transmittance decreases as the exposure amount increases, and the internal photocuring becomes insufficient, which is not preferable.

  The photosensitive resin composition includes a photopolymerizable compound having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, a dye such as malachite green, tribromomethylphenylsulfone, if necessary. , Photochromic agents such as leuco crystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion-imparting agents, leveling agents, peeling promotion An agent, an antioxidant, a fragrance, an imaging agent, a thermal crosslinking agent and the like can be contained in an amount of about 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of the component (A) and the component (B). These may be used alone or in combination of two or more.

  The photosensitive resin composition may be added to 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. It can melt | dissolve and can apply | coat as a solution about 30 to 60 weight% of solid content.

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, and an iron-based alloy, dried, and then covered with a protective film as necessary. Or used in the form of a photosensitive element.
Moreover, although the thickness of the photosensitive resin composition layer changes with uses, it is preferable that it is about 1-100 micrometers by the thickness after drying. In the case of using a liquid resist coated with a protective film, examples of the protective film include polymer films such as polyethylene and polypropylene.

The photosensitive element can be obtained, for example, by applying and drying a photosensitive resin composition on a polymer film such as polyethylene terephthalate, polypropylene, polyethylene, or polyester as a support. 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.
The thickness of these polymer films is preferably 1 to 100 μm. One of these polymer films may be laminated on both sides of the photosensitive resin composition layer as a support for the photosensitive resin composition layer, and the other as a protective film for the photosensitive resin composition. As the protective film, those having a smaller adhesive strength between the photosensitive resin composition layer and the protective film than the adhesive strength between the photosensitive resin composition layer and the support are preferable, and a film having a low fish eye is preferable.
In addition to the photosensitive resin composition layer, the support and the protective film, the photosensitive element may have an intermediate layer or protective layer such as a cushion layer, an adhesive layer, a light absorption layer, or a gas barrier layer. .

The photosensitive element is stored, for example, as it is or after a protective film is further laminated on the other surface of the photosensitive resin composition layer and wound around a cylindrical core. In addition, it is preferable to wind up so that a support body may become the 1st outer side at this time. 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.
Examples of the winding core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer).

In producing a resist pattern using the photosensitive element, if the protective film is present, the protective film is removed and then the photosensitive resin composition layer is heated to about 70 to 130 ° C. For example, a method of laminating by pressure bonding to a circuit forming substrate at a pressure of about 0.1 to 1 MPa (about 1 to 10 kgf / cm ² ) may be mentioned, and the lamination may be performed under reduced pressure. The surface to be laminated is usually a metal surface, but is not particularly limited.
The photosensitive resin composition layer 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.
Next, after exposure, when a support is present on the photosensitive resin composition layer, the support 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 manufactured by removing the unexposed portion with development or the like and developing. 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.

For the etching of the metal surface performed after development, for example, a cupric chloride solution, a ferric chloride solution, an alkaline etching solution, or the like can be used.
When a printed wiring board is produced using the photosensitive element of the present invention, the surface of the circuit forming substrate is treated by a known method such as etching or plating using the developed resist pattern as a mask. Examples of the plating method include copper plating, solder plating, nickel plating, and gold plating. 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. 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.

Hereinafter, the present invention will be specifically described by way of examples.
(Examples 1 and 2 and Comparative Examples 1 to 3)
The materials shown in Table 1 and Table 2 were blended to obtain a photosensitive resin composition solution.

（単位はｇ）

(Unit is g)

（単位はｇ）

(Unit is g)

In addition, the material used in Table 1 and Table 2 is shown below.
BPE-500: a compound in which m + n = 10 (average value) in the following formula (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.)

Ｍ−１１３：下記式で示されるノニルフェニルポリエチレン変性アクリレート
（東亜合成化学株式会社製商品名）

M-113: Nonylphenyl polyethylene modified acrylate represented by the following formula (trade name, manufactured by Toagosei Co., Ltd.)

ＩＲＧＡＣＵＲＥ ＯＸＥ０１：下記式で示されるオキシムエステル化合物
（チバ・スペシャルケミカルズ株式会社製商品名）

IRGACURE OXE01: an oxime ester compound represented by the following formula (trade name, manufactured by Ciba Special Chemicals Co., Ltd.)

ＰＡＩ−１０１：下記式で示されるオキシムエステル化合物
（みどり化学株式会社製商品名）

PAI-101: Oxime ester compound represented by the following formula (trade name, manufactured by Midori Chemical Co., Ltd.)

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 Ltd.), and dried for 10 minutes with a 100 ° C. hot air convection dryer. Then, it was protected with a polyethylene protective film (trade name NF-13, manufactured by Tamapoly Co., Ltd.) to obtain a photosensitive element. The film thickness after drying of the photosensitive resin composition layer was 40 μm.
Next, a polishing machine having a brush equivalent to # 600 on the copper surface of a copper clad laminate (trade name MCL-E-61, manufactured by Hitachi Chemical Co., Ltd.), which is a glass epoxy material in which copper foil (thickness 35 μm) is laminated on both sides. (Sankei Co., Ltd.) was used for polishing, washing with water, and drying with an air stream. The obtained copper-clad laminate was heated to 80 ° C., and the photosensitive resin composition layer was placed on the copper surface. Lamination was carried out at a speed of 1.5 m / min using a 120 ° C. heat roll while peeling off the protective film.
Next, using an exposure machine (trade name HMW-201B, manufactured by Oak Co., Ltd.) having a high-pressure mercury lamp lamp, a stove 21-step tablet was placed on the test piece as a negative and exposed.

Next, the polyethylene terephthalate film is peeled off and sprayed with a 1% by weight sodium carbonate aqueous solution at 30 ° C. (spray (development) time: minimum development time × 2), and after removing the unexposed part, on the copper clad laminate. The number of steps (x / 21) of the step tablet of the formed photocured film was measured, and the exposure amount indicating ST = 8/21 was defined as photosensitivity. It shows that photosensitivity is so high that this exposure amount is small.
The minimum development time was measured as the time when the unexposed resist was completely removed by the development process.
As for resolution, a photo tool having a stove 21-step tablet and a photo tool having a wiring pattern with a space width / line width of 30/400 to 200/400 (unit: μm) are closely attached as a negative for resolution evaluation. Exposure was carried out with an energy amount such that the number of steps remaining after development of the 21-step tablet of fur (development time: minimum development time × 2) was 8.0. Here, the resolution was evaluated based on the smallest value of the space width between the line widths in which the unexposed portion could be cleanly removed by the development process. The smaller the numerical value, the better the resolution evaluation.
Adhesion is achieved by adhering a phototool having a stove 21-step tablet and a phototool having a wiring pattern with a line width / space width of 30/400 to 200/400 (unit: μm) as a negative for adhesion evaluation. The exposure was carried out with an energy amount such that the number of remaining step steps after development (development time: minimum development time × 2) of the 21-step tablet of Stöffer was 8.0. Here, after the development, the resist forming the line is firmly attached to the substrate so that there is no part where the resist is peeled off, and the line width is the most where the line does not meander or bend. Evaluation was based on small values. The smaller the numerical value, the better the evaluation of adhesion. Moreover, the maximum absorption wavelength (nm) before and behind light irradiation of a photoinitiator was measured, and those results were collectively shown in Table 3.

表３から明らかなように、実施例１、２は高感度で且つ解像度・密着性が優れている。

As is apparent from Table 3, Examples 1 and 2 have high sensitivity and excellent resolution and adhesion.

Claims (6)

In the photosensitive resin composition having (A) a binder polymer, (B) an ethylenically unsaturated photopolymerizable monomer, and (C) a photopolymerization initiator, the maximum absorption wavelength after light irradiation of the (C) photopolymerization initiator. Is shifted to a lower wavelength side by 30 nm or more than the maximum absorption wavelength before light irradiation. The photosensitive resin composition according to claim 1, wherein the (A) binder polymer comprises at least (meth) acrylic acid and (meth) acrylic acid ester as a constituent monomer of a copolymerization component. The said (C) photoinitiator has an oxime ester bond, The photosensitive resin composition of Claim 1 or Claim 2 characterized by the above-mentioned. The photosensitive element formed by apply | coating the photosensitive resin composition in any one of Claim 1 thru | or 3 on a support body, and drying. The photosensitive element according to claim 4 is laminated on a circuit forming substrate so that the photosensitive resin composition layer is in close contact, irradiated with an actinic ray in an image form, and an exposed portion is photocured, unexposed. A method for producing a resist pattern, wherein the portion is removed by development. A method for producing a printed wiring board, comprising etching or plating a circuit forming substrate on which a resist pattern has been produced by the method for producing a resist pattern according to claim 5.