JP2002139832A - Photosensitive resin composition and printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for a circuit layer-to- layer adhesive developable with an aqueous developing solution using no organic solvent, excellent in various characteristics necessary for the insulating layer of a multilayer wiring board, e.g. adhesion to a substrate and having particularly superior heat resistance and to provide a high reliability printed wiring board using the composition. SOLUTION: The photosensitive resin composition contains a compound (A) having at least one phenolic hydroxyl group and at least one acryloyl group or methacryloyl group in one molecule, a compound (B) having at least two dihydrobenzoxazine rings in one molecule and a photopolymerization initiator (C) as essential components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition having both ultraviolet-curing properties and thermosetting properties, which is useful for forming an insulating layer of a multilayer printed wiring board by a build-up method. The present invention relates to a printed wiring board using the same.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high performance of electronic devices, printed wiring boards have been increased in density and multilayered. In the case of a double-sided board or a multilayer wiring board having more circuit layers, a so-called via hole is usually formed by metal plating on the inner surface of the hole after a drilling step to achieve conduction between circuit layers. ing. At present, it is desired to minimize the area occupied by the via holes in order to mount components at high density on a wiring board.

[0003] However, conventional drilling has reached the limit of reducing the diameter from a technical and cost perspective.
For this reason, many via-hole forming methods that do not rely on a drilling method have been proposed. For example, (1) a photosensitive adhesive is used as an insulating layer, this adhesive is applied on a pre-formed inner layer circuit, holes are formed by patterning with light, and copper plating is performed thereon. (2) A method of forming a hole in a via hole of an insulating layer by a laser, (3) A resin soluble in a specific developer is laminated together with a copper foil, and a copper in a via hole portion is formed. After the foil is removed by etching, the exposed insulating resin is removed with a developing solution to form a hole, and a conductive paste is buried or copper plating is performed to achieve conduction between layers.

[0004] These manufacturing methods are described in "Surface Mount Technology, V
ol. 4, No. 1 (1994) Nikkan Kogyo Shimbun). Among them, a manufacturing method combining a photosensitive adhesive and the formation of a circuit layer by plating is particularly effective in the following points. That is, it is possible to form a plurality of openings at one time, to be excellent in productivity, to reduce the diameter to a size corresponding to the resolution of the photosensitive adhesive, and to easily form a non-through through hole (IVH). Therefore, the degree of freedom of design is high, and furthermore, multi-layering can be easily achieved by repeating the same process.

In the above manufacturing process, it is needless to say that the performance of the photosensitive adhesive is important. However, when the required performance is enumerated, first, a uniform coating without voids is formed on an inner layer circuit having some unevenness. Able to form a film, having photosensitivity and developability, having a resolution capable of forming a desired via hole, having resistance to various chemicals such as a plating solution and a surface treatment agent, To prevent cracks from being generated when cracks are added.

The characteristics required after the printed wiring board is formed include electrical insulation, solder heat resistance when mounting components, and wire bonding resistance and heat cycle resistance when a semiconductor is directly mounted. These heat resistance properties require that the adhesive have a high glass transition point. As described above, there is no photosensitive adhesive having many performances, and this is one of factors that hinder the spread of the process.

At present, so-called photo-solder resists are known as photosensitive insulating materials, and in many cases, they are used as adhesives between circuit layers. For example, Japanese Patent Application Laid-Open No. 4-148590 describes a multilayer wiring board in which photovias are formed using a photosensitive epoxy resin. However, the photosensitive epoxy resin used in this method uses an organic solvent as a developing solution, and thus has problems in working environment, processing of a used developing solution, and the like.

[0008]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has been made as a result of intensive studies, and can be developed with an aqueous developing solution which does not use an organic solvent, and has good adhesion to a substrate. Excellent in various properties required for the insulating layer of the multilayer wiring board,
Another object of the present invention is to provide a photosensitive resin composition for a circuit interlayer adhesive having particularly excellent heat resistance, and a highly reliable printed wiring board using the same.

[0009]

That is, the present invention relates to a compound (A) having at least one phenolic hydroxyl group and at least one acryloyl group or methacryloyl group in one molecule, and at least two compounds in one molecule. A photosensitive resin composition comprising a compound (B) having two dihydrobenzoxazine rings and a photopolymerization initiator (C) as essential components, and further as a circuit interlayer adhesive (insulating layer) as described above. A printed wiring board manufactured using a photosensitive resin composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The compound (A) having at least one phenolic hydroxyl group and at least one acryloyl group or methacryloyl group in one molecule used in the present invention includes phenol, cresol, bisphenol A A compound having a phenolic hydroxyl group, such as
A compound obtained by reacting glycidyl acrylate or glycidyl methacrylate with a novolak resin obtained by reacting with an aldehyde such as formaldehyde in the presence of a base catalyst such as triethylamine (however, The ratio of the phenolic hydroxyl group to the acryloyl group or the methacryloyl group is not particularly limited), and specific examples include, but are not limited to, methacrylic acid-modified bisphenol A novolak.

The compound (B) having at least two dihydrobenzoxazine rings in one molecule includes:
The compound is not particularly limited as long as it is a compound having a plurality of dihydrobenzoxazine ring structures as shown in the formula 1 (a) and reacting with the aromatic ring of phenol by opening of the dihydrobenzoxazine ring. , As in Equation 1,
It is synthesized from a compound having a plurality of phenolic hydroxyl groups, a primary amine and formalin.

[0012]

Embedded image In the formula, R is a methyl group, a phenyl group, or a phenyl group substituted with at least one alkyl group or alkoxyl group having 1 to 3 carbon atoms.

In the compound having a plurality of phenolic hydroxyl groups, hydrogen must be bonded to one of the ortho positions to each phenolic hydroxyl group in the aromatic ring. Examples of such compounds include catechol Phenol resins such as resorcinol, 1,5-dihydroxynaphthalene, dihydroxynaphthalenes such as 2,6-dihydroxynaphthalene, bisphenols such as bisphenol-A and bisphenol-F, phenol novolak resins, resole resins, and melamine phenol resins. No.

Examples of primary amines include aromatic amines such as aniline and toluidine, and aliphatic amines such as methylamine and ethylamine. The aromatic amine is more suitable for the thermosetting resin composition. However, the curing speed tends to be low, but the heat resistance tends to increase.

As formaldehyde, either formalin, which is an aqueous formaldehyde solution, or paraformaldehyde, which is a polymer thereof, can be used.

The reaction solvent used in the reaction of the formula 1 is 1
-Propanol, 2-propanol, 1-butanol, 1,
A single or mixed solvent such as 4-dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and the like can be used.

In order to react all of the phenolic hydroxyl groups, the primary amine 1
It is desirable to use at least 2 moles of formaldehyde and at least 2 moles of formaldehyde. The reaction is preferably performed at a temperature of 100 ° C. or more and 130 ° C. or less. When the reaction temperature is lower than 100 ° C., the reaction does not proceed. When the reaction temperature is higher than 130 ° C., the benzoxazine ring once formed opens, and a bonding reaction occurs with another phenolic hydroxyl group. It is not preferred because the oligomerization of is promoted. The reaction time depends on the reaction temperature, but is complete in 2 to 6 hours.

After completion of the reaction, the solvent is distilled off, and if necessary, an alkali washing operation is performed, and a vacuum drying operation is performed to remove unreacted phenols, primary amines, formaldehyde and the solvent. Compound (B) having at least two dihydrobenzoxazine rings in the molecule is obtained.

Next, the photopolymerization initiator (C) used in the present invention.
Examples of benzoin, benzoin methyl ether, benzoin alkyl ethers such as benzoin isopropyl ether, acetophenone, 2,2-dimethoxy-2-acetophenone, 2,2-dimethoxy-2-
Acetophenones such as phenylacetophenone and 1,1-dichloroacetophenone; anthraquinones such as 2-methylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone; 2,4-dimethylthioxanthone;
Thioxanthone such as -chlorothioxanthone and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; and xanthones. Furthermore, such a photopolymerization initiator (C) can be used in combination with one or more selected from known and commonly used photopolymerization accelerators such as benzoic acid-based and tertiary amine-based ones according to a conventional method. .

In the photosensitive resin composition of the present invention, in addition to the above-mentioned essential components, the following various components can be blended as required, whereby the handleability, curability and curability of the composition can be improved. It is possible to further improve the physical properties.

One of the additional components is a photopolymerizable vinyl compound (D) containing at least one acryloyl group or methacryloyl group in one molecule, for example, β-hydroxyethyl acrylate, β-hydroxy Propyl acrylate, glycidyl acrylate,
β-hydroxyethyl acryloyl phosphate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, trimethylol propane di Acrylates such as acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, tris (2-acryloyloxyethyl) isocyanurate and the like Mono-, di-, tri-, and higher polyesters and bisphenols obtained by esterification reaction of methacrylates having acryloyl group of methacryloyl group as a methacryloyl group, and polybasic acid with hydroxylalkyl (meth) acrylate A-type epoxy acrylate, novolak-type epoxy acrylate, urethane acrylate, and the like can be given, and it is preferable to use a polyfunctional monomer, oligomer, or prepolymer having two or more acryloyl groups or methacryloyl groups in one molecule. .

Of the photopolymerizable vinyl compound (D),
For example, those having a low viscosity function as a so-called reactive diluent, and the viscosity of the composition of the present invention can be adjusted without impairing the curability. Further, if the polyfunctional photopolymerizable vinyl compound (D) is blended, the crosslink density of the obtained cured product can be increased. Further, the amount of the photopolymerizable vinyl compound (D) can effectively improve the ultraviolet curability and developability of the composition, the adhesion of the cured product to the substrate, and the like.

Other additional components include an organic solvent (E), for example, ketones such as methyl ethyl ketone and cyclohexanone, ethers such as diethyl ether, tetrahydrofuran and 1,4-dioxane, methyl cellosolve, ethyl Cellsolves such as Cellsolve, ethyl acetate, esters such as Cellsolve acetate, nitriles such as acrylonitrile, formamides such as N, N-dimethylformamide, and pyrrolidones such as N-methyl-2-pyrrolidone. However, it is desirable to use some polar compounds such as ketones and formamides. These organic solvents (E) can adjust the composition to an appropriate viscosity, and can effectively improve the handleability of the composition.

The composition of the present invention may further contain, if necessary, known additives in addition to the above components. For example, barium sulfate, barium titanate,
Inorganic fillers such as silicon oxide, amorphous silica, zirconium silicate, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, mica, phthalocyanine blue, phthalocyanine green, iosin green, disazo yellow, crystal Colorants such as violet, titanium oxide, carbon black, and naphthalene black; polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, and phenothiazine; thickeners such as asbestos, orben, and bentone; silicone-based, fluorine-based, and polymer-based Antifoaming agents and leveling agents, as adhesion-imparting agents, imidazole-based, thiazole-based, triazole-based,
Examples include a silane coupling agent.

Next, the mixing ratio of each component in the composition of the present invention will be described. The compounding amount of the compound (B) having a dihydrobenzoxazine ring is 10 to 500 parts with respect to 100 parts by weight (hereinafter, referred to as parts) of the compound (A) having a phenolic hydroxyl group and an acryloyl group or a methacryloyl group. , Preferably 20 to 250 parts. If the amount is less than 10 parts, the physical properties such as heat resistance and moisture resistance of the cured product may not be improved. If the amount exceeds 500 parts, the ultraviolet curability and the like will be reduced.

The compounding amount of the photopolymerization initiator (C) is 0.2 to 50 based on the total amount (100 parts) of the compound (A) and the photopolymerizable vinyl compound (D) when used together.
Parts, preferably 2 to 20 parts. If the amount is less than 0.2 part, the ultraviolet curability may be insufficient, and
Even if it is blended in more than 10 parts, not only the curability does not improve any more, but also the photopolymerization initiator (C) remaining unreacted,
The physical properties of the cured product may be reduced. The compounding amount of the photopolymerizable vinyl compound (D) is 0.1 to 300 with respect to 100 parts of the total amount of the compound (A) and the compound (B).
Parts, preferably 3 to 100 parts. If the amount is more than 300 parts, the heat resistance and moisture resistance of the cured product may be reduced.

When the organic solvent (E) is used, the compounding amount is 0.1 to 300 parts, preferably 3 to 100 parts, based on 100 parts of the total amount of the compound (A) and the compound (B). . The organic solvent (E) is generally added for adjusting the viscosity of the composition of the present invention, adjusting the amount of coating (coating thickness), and the like. However, if it is added too much, the viscosity of the composition becomes too low. In addition to making it difficult to form a uniform film, the energy and time required for drying and removing the solvent are excessively increased.

When the curing accelerator (F) is used, the compounding amount is 0.1 to 5 parts, preferably 0.1 to 1 part with respect to 100 parts of the total amount of the compound (A) and the compound (B). I do. If the amount is too large, the storage stability of the composition of the present invention is reduced.

When the inorganic filler is used, the compounding amount is preferably 1 to 90% by weight, more preferably 5 to 60% by weight of the composition of the present invention.

The photosensitive resin composition of the present invention can be obtained by mixing the above-mentioned components in the same manner as a known photosensitive resin composition and, if necessary, kneading with a three-roll mill or the like. it can.

When the photosensitive resin composition of the present invention is used for an insulating layer of a multilayer printed wiring board in which wiring layers and insulating layers are alternately formed, first, the insulating resin is coated on an insulating base material or an insulating layer. An inner layer circuit is formed. As a forming method, a known method used for manufacturing a printed wiring board, such as a panel plating method, a subtractive method, and an additive method, can be used. Next, the photosensitive resin composition of the present invention is applied on a printed wiring board on which a wiring layer serving as an inner layer circuit has been formed.
At this time, in order to improve the adhesion, the surface of the metal forming the wiring layer may be roughened in advance. The coating can be performed by a screen printing method, a curtain coater, a spin coater, a spray, or the like, and a coating film can be formed by a method such as heating and drying in a hot air circulation furnace or the like.

Further, the photosensitive resin composition of the present invention is applied on a suitable substrate such as a polyethylene terephthalate (PET) film and dried once to form the resin composition B
Staged, so-called dry film form,
It can also be used by crimping on a circuit.

Thereafter, exposure is performed by direct irradiation with a laser beam or through a photomask on which a pattern is formed, and selectively by an actinic ray such as a high-pressure mercury lamp or a metal halide lamp in a contact manner, and an unexposed portion is developed with a developing solution. , A photo via hole is formed. In the exposure step, irradiation with laser light or exposure with active light may be performed in a non-contact manner in a wet state where the coating film is not dried.

As a developer for forming the photovia hole, an aqueous alkali solution such as sodium hydroxide, potassium hydroxide, or tetramethylammonium hydroxide can be used. Although an organic solvent such as methyl ethyl ketone, methyl cellosolve, and cyclohexanone can be used, it is preferable to use an alkaline aqueous solution in view of the working environment.

After the pattern is formed, a heat treatment at 170 to 300 ° C. is performed to obtain an adhesive layer that satisfies various characteristics as an insulating layer. In addition, various characteristics are further improved by performing exposure to active energy rays such as ultraviolet rays after development as required.

In order to form a multilayer, a conductor layer is formed on the insulating layer by plating, and then a circuit is formed by the above-mentioned method to form a wiring layer. The surface of the insulating layer may be roughened in advance by a method used in a known method for manufacturing a printed wiring board, such as using an oxidizing agent such as a salt. Further, the wiring layer and the insulating layer are alternately formed by coating the photosensitive resin composition of the present invention on this wiring layer or pressing a dry film of the photosensitive resin composition by pressure bonding, and repeating the above steps. Is obtained.

[0037]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Prepared using a compound having a dihydrobenzoxazine ring synthesized in advance, for each of the compositions of Examples and Comparative Examples, for evaluation of properties, solder resistance,
The glass transition temperature Tg, resolution, and adhesion were measured. The measuring method of each characteristic was as follows. In addition, a synthesis example,
Parts in Examples and Comparative Examples represent parts by weight.

[Solder Resistance] According to the test method of JIS-C6481, the operation of immersing a test piece of a multilayer printed wiring board in a solder bath at 260 ° C. for 15 seconds was performed three times, and the state of the adhesive layer was checked each time. The adhesiveness was comprehensively evaluated. In the evaluation, there was no abnormality in the appearance of the coating film.
Or there was peeling.

[Glass Transition Temperature Tg] A sheet-like cured product of the adhesive was prepared, and the glass transition temperature was measured by a static thermomechanical measurement method.

[Resolution] It was determined by observing with a microscope whether or not vias were formed by using a photomask having a black dot with a diameter of 100 μm. Judgment methods were as follows: Via formation possible: .largecircle .; Via formation impossible: .times.

[Adhesion] According to the test method of JIS-D0202, 100 pieces of 1 mm × 1 mm squares were cut on the coating film of the evaluation sample, and the state of the peeling after the peeling test with a cellophane tape was visually observed. Observed.
It is represented by the number of remaining grids, and the larger the number, the better the adhesion.

[Synthesis Example 1] 300 parts of 1-propanol and 324 parts of 37% formalin were placed in a flask, and a liquid mixture of 200 parts of 1-propanol and 186 parts of aniline was stirred while maintaining the liquid temperature at 5 ° C. Was added dropwise. Further, a solution prepared by dissolving 200 parts of bisphenol F (trade name: bisphenol FD, manufactured by Honshu Chemical Co., Ltd.) in 1000 parts of 1-propanol was similarly added dropwise.
The temperature was raised to the reflux temperature, and the reaction was continued for 2 hours. Thereafter, the solvent was distilled off to obtain a desired compound I having a dihydrobenzoxazine ring.

[Synthesis Example 2] In Synthesis Example 1, except that a mixture of 100 parts of 1-propanol and 62 parts of methylamine was used instead of a mixture of 200 parts of 1-propanol and 186 parts of aniline. Compound having desired dihydrobenzoxazine ring in the same manner as in Synthesis Example 1.
I got II.

Example 1 100 parts of methacrylic acid-modified bisphenol A novolak (phenolic hydroxyl equivalent: 383, methacrylic modification ratio: 50 mol%), compound I 4
5 parts, 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651 manufactured by Nippon Ciba Geigy) 8
Parts, 30 parts of polypropylene glycol diacrylate (Neomer PA-305 manufactured by Sanyo Kasei Co., Ltd.), 60 parts of methyl ethyl ketone, 0.5 part of triethylamine, 60 parts of barium sulfate, and 1 part of an antifoaming agent, and the mixture was rolled with three rolls. 3
The composition was prepared by kneading twice.

Example 2 Compound I used in Example 1
A composition was prepared in the same manner as in Example 1, except that 45 parts were replaced with 33 parts of compound II and 60 parts of methyl ethyl ketone were replaced with 55 parts.

Comparative Example 1 45 parts of the compound I used in Example 1 was replaced with a cresol novolac epoxy 45.
A composition was prepared in the same manner as in Example 1 except that the part (D660) was changed.

Comparative Example 2 100 parts of methacrylic acid-modified bisphenol A novolak used in Example 1 was
A composition was prepared in the same manner as in Example 1, except that 32 parts of bisphenol A novolak was used.

Comparative Example 3 100 parts of methacrylic acid-modified bisphenol A novolak used in Example 1 was used.
Except that 100 parts of methacrylic acid-modified bisphenol A novolak (methacrylic modification ratio: 100 mol%) was replaced with 100 parts
A composition was prepared in the same manner as in Example 1.

Each of the compositions obtained in the above Examples and Comparative Examples was applied on a PET film, and was applied in a hot air circulation furnace.
The film was dried at 0 ° C. for 20 minutes to obtain a dry film. This dry film was press-bonded to a copper through-hole printed wiring board, applied with a photomask, and irradiated with ultraviolet rays at 300 mJ / cm ² by an exposure apparatus manufactured by Oak Manufacturing Co., Ltd. Subsequently, the unexposed portions were removed with a 1.5% aqueous sodium hydroxide solution and developed. After exposure to 300 mJ of ultraviolet light again, thermal curing was performed at 200 ° C. for 60 minutes to obtain each evaluation sample, which was subjected to the above-described evaluation test. The evaluation results are shown in Table 1.

[0050]

[Table 1]

As can be seen from the results shown in Table 1, the photosensitive resin composition of the present invention has excellent heat resistance and adhesiveness as a circuit interlayer adhesive, has high resolution, and has high reliability in printed wiring. Useful for board manufacturing.

[0052]

The photosensitive resin composition of the present invention not only forms a cured product having excellent heat resistance and adhesiveness to a substrate, but also uses a water-based developer which does not use an organic solvent to obtain a high-performance resin composition. It can be developed at a resolution and is suitable as an adhesive between circuit layers. A highly reliable printed wiring board using this can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 TF term (Reference) 2H025 AA02 AA10 AA14 AB11 AB15 AC01 AD01 BC14 BC32 BC42 BC86 CA01 CA27 CC20 FA03 FA17 4J002 CC07W CC07X CC08W ED086 EE026 EE056 EV316 FD146 GP03 5E346 AA12 AA15 BB01 CC08 DD01 DD11 EE38 EE39 GG02 HH11 HH13 HH18

Claims (2)

[Claims] 1. A compound having at least one phenolic hydroxyl group and at least one acryloyl group or methacryloyl group in one molecule (A), and a compound having at least two dihydrobenzoxazine rings in one molecule A photosensitive resin composition comprising (B) and a photopolymerization initiator (C) as essential components. 2. A multilayer printed wiring board in which wiring layers and insulating layers are alternately formed, wherein the insulating layer is made of the photosensitive resin composition according to claim 1.