KR20060081098A - Negative liquid photoimageable resist composition - Google Patents

Abstract

The present invention provides a negative liquid photoresist composition further comprising a melamine resin in addition to a base polymer, a photopolymerization monomer, a photopolymerization initiator, an additive, and a solvent, which can increase the efficiency of the photopolymerization initiator by the amino group of melamine, thereby providing a photopolymerization initiator. The resist can be highly sensitive without increasing the amount of, and the amount of the photopolymerizable monomer can be reduced by lowering the glass transition temperature of the base polymer to realize a highly sensitive microcircuit.

Description

Negative liquid photoimageable resist composition

The present invention relates to a negative liquid photoresist composition used for circuit mounting of a printed circuit board (Printed Circuit Board).

Negative liquid photoresist is characterized by excellent fine wire adhesion and resolution compared to dry film, but many negative liquid photoresists do not exhibit such characteristics. For this reason, the liquid photoresist should be uniformly coated with a liquid material on the substrate by roller coating or dip coating and free from defects such as pinholes. It is not good or has a problem that the film defects such as pinholes, Bernard cells and the like.

On the other hand, fine wire adhesion and resolution are opposite to each other in order to improve fine wire adhesion, the fine width of the line exposed while completely washed out when the unexposed part develops should remain attached to the copper plate without receiving a small exposure amount. In order to increase the resolution, the unexposed part should be removed quickly when developing. If the viscosity is high, the resist will not be removed quickly at the boundary part, so the resolution will be reduced. In other words, the resist between the exposed portion and the unexposed portion has to have a large difference in developability under a certain developing condition so that a resist having excellent fine line adhesion and resolution can be simultaneously produced.

In order to satisfy these properties at the same time, a resist composition such as a base polymer or monomer should have good adhesiveness to the copper plate and have appropriate developability when contacted with a developer. Examples of techniques for solving such technical problems and improving fine line adhesion and resolution include U.S. Patent Nos. 6,037,100, 6,271,595, 6,103,449, and 5,935,761. In the end, these techniques were introduced to introduce new ones in each component raw material, to change the chemical structure of existing raw materials, and to prepare a crude liquid solution to optimize the ratio of components in order to improve fine line adhesion and resolution.

Most photopolymerization monomers and additives introduced to increase fine wire adhesion and resolution are not clean sidewall of the circuit after development, and surface hardness is increased when a lot of photopolymerization initiators and photopolymerization monomers are used to increase the sensitivity of the resist. Lowering or increasing the surface hardness of the resist after UV irradiation is a cause of poor adhesion.

Accordingly, the present invention has excellent resolution and adhesion necessary to make a fine circuit shape as the density of printed circuit boards and the development of semiconductor packaging technology increase the density of the circuit line width, and in the high sensitivity type resist for improving productivity It is an object of the present invention to provide a negative type liquid photoresist composition which can solve poor coating properties and poor adhesion due to increase in surface hardness of resist after UV irradiation.

The negative liquid photoresist composition of the present invention for achieving the above object comprises a base polymer, a photopolymerization monomer, a photopolymerization initiator, an additive and a solvent, wherein the melamine resin represented by the following formula (1) in the total resin composition Characterized in that it further comprises 1 to 10% by weight.

In the above formula, R ₁ to R ₆ are the same as or different from each other, and are represented by -CH ₂ OR ₇ , and R ₇ is an alkyl group having 1 to 6 carbon atoms.

The present invention will be described in more detail as follows.                     

(1) base polymers

Polymers used for ordinary negative photoresists include acrylic resins, polyester resins, polyurethane resins, and the like.

Of these, methacryl copolymer (copolymerization with ethylenically unsaturated carboxylic acid or other monomer, if necessary), which is a kind of acrylic resin, is important. Methacrylic copolymers containing acetoacetyl group may also be used as the methacryl copolymer. Methacrylic monomers that can be used to polymerize methacryl copolymers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, dimethylaminoethyl methacrylate Dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, and the like.

Among ethylenically unsaturated carboxylic acids, monoacrylic acids such as acrylic acid, methacrylic acid, and crotonic acid are commonly used.

Maleic acid, fumaric acid, dicarboxylic acids such as itaconic acid, or anhydrides thereof, or half esters thereof may also be used. Of these, acrylic acid and methacrylic acid are particularly used and exhibit excellent physical properties.

Other copolymerizable monomers include acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, and vinyl acetate. (vinyl acetate), alkyl vinyl ethers, and the like.

There are three coating methods of negative liquid photoresist: roller coating, dip coating and screen coating. For each coating there is an optimum viscosity to achieve the best coating thickness and surface printability. Generally, the negative liquid photoresist is dried at 110 ° C. for about 10 minutes. The hardness of the liquid photoresist after drying should have a value of 2H or more, and the glass transition temperature (Tg) of the base polymer should be at least 100 ° C. in order for the hardness of the resist after drying to have a value of 2H or more. This is because the entire photoresist composition contains a large amount of low molecular compounds such as photopolymerization monomers as well as the base polymer, and thus the glass transition temperature of the entire composition in which they are mixed together is much lower than the glass transition temperature of the base polymer alone.

In the present invention, after the composition using a base polymer having a variety of glass transition temperature, the hardness was measured to select the optimal base polymer. If the glass transition temperature of the base polymer is too high, the resist is too hard to be broken, peeling may occur during etching, and underplating defects may occur during plating. On the other hand, if the glass transition temperature of the base polymer is too low, there is a problem that the hardness of the resist is lowered.

When selecting a base polymer, the molecular weight and acid value as well as the glass transition temperature are very important. If the molecular weight is too small, fine wire adhesion and etching resistance are lowered. If the molecular weight is too large, the developing speed is slowed and the resolution is poor. If the acid value is too small, it will not be developed. If the acid value is too high, the developing speed will be too high. Therefore, in order to obtain a suitable development speed, resolution, and hardness after drying, it is necessary to select a base polymer by matching conditions such as molecular weight, glass transition temperature, and acid value of the base polymer.

The base polymer used in the present invention is an acrylic ester polymer dissolved in 1-methoxy-2-propanol solvent, the glass transition temperature is 100 to 150 ℃, the acid value is 40 to 150 mgKOH / g, the weight average molecular weight (Mw) is 20,000 to 60,000.

Such base polymers are usually included in 20 to 60% by weight of the total photoresist composition.

(2) photopolymerization monomer

The photopolymerization monomer is an ethylenically unsaturated compound, and includes a polyfunctional monomer and a monofunctional monomer. Examples of the polyfunctional monomer include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and propylene glycol dimethacryl. Latex, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate , Pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentamethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, 2-hydroxy-3 -Methacryloyloxypropyl methacrylate, ethylene glycol diglycidyl ether dimethacrylate, diethylene glycol di A receiver ether dimethacrylate, phthalic acid diglycidyl ester dimethacrylate, glycerol polyglycidyl ether, such as polymethacrylates.

In addition to the polyfunctional monomer, an appropriate amount of the monofunctional monomer can also be used. Examples of monofunctional monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-phenoxy-2-hydroxypropyl methacrylate, 2-metha Chryroyloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl methacrylate, glycerin monomethacrylate, 2-methacryloyloxyethyl acid phosphate, methacrylate of phthalic acid derivatives, N -Methylol methacrylamide, and the like.

Such photopolymerization monomer is included in 10 to 40% by weight of the total composition.

(3) photopolymerization initiator

As photopolymerization initiator, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butylether, benzoin phenylether, benzyl diphenyl disulfide, benzyl dimethyl ketal, anthraquinone, naphthoquinone, 3, 3-dimethyl-4-methoxybenzophenone, benzophenone, p, p'-bis (dimethylamino) benzophenone, p, p'-bis (diethylamino) benzophenone, p, p'-diethylaminobenzo Phenone, pivalon ethyl ether, 1,1-dichloro acetophenone, pt-butyldichloroacetophenone, dimer of hexaaryl-imidazole, 2,2'-diethoxyacetophenone, 2,2'-diethoxy 2-phenylacetophenone, 2,2'-dichloro-4-phenoxyacetophenone, phenyl glyoxylate, α-hydroxyisobutylphenone, dibenzospan, 1- (4-isopropylphenyl) -2 -Hydroxy-2-methyl-1-propanone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, tri-bromophenylsulfone, tribromomethylphenylsulfoneIt can be given.

The amount of the photopolymerization initiator added is preferably about 1-20 parts by weight based on 100 based on the amount of the base polymer and the photopolymerization monomer.

(4) melamine resin

As the most important configuration of the present invention, the melamine resin represented by Chemical Formula 1 is used to increase the efficiency of the photoinitiator.

Melamine resin can increase the efficiency of photopolymerization initiator by melamine amino group, making the resist highly sensitive without increasing the amount of photopolymerization initiator, and by reducing the glass transition temperature of the base polymer, it is possible to reduce the amount of photopolymerization monomer and thus high sensitivity. The circuit can be realized.

The amount of melamine resin is 1 to 10% by weight of the total photoresist composition is suitable, if the content is less than 1% by weight does not show the photosensitizing efficiency, when it exceeds 10% by weight lower the resist glass transition temperature to reduce the surface of the coating film It becomes tacky and the adhesion is poor.

(5) additives

The volatile organics added are compatible with the photoresist composition and should not interfere with film formation when coating the photoresist composition. Typical examples thereof may include plasticizers used as softening agents such as vinyl chloride resins. Specific examples of the phthalic ester include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, Diisodecyl phthalate, butylbenzyl phthalate, diisononyl phthalate, ethyl phthalethyl glycolate, dimethyl isophthalate, dichlorohexyl phthalate, and the like; esters of fatty acids or arimatic acid, such as dioctyl adipate ( dioctyl adipate, diisobutyl adipate, dibutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, dibutyl sebacate ( dibutyl sebacate) and dioctyl sebacate.

Other plasticizers other than the above plasticizers include glycerol triacetate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, tris-chloroethyl phosphate, tris-dichloropropyl phosphate, triphenyl phosphate, triphenyl Tricresyl phosphate, tricsylenyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, xylenyl diphenyl phosphate , Trilauryl phosphate, tricetyl phosphate, tristearyl phosphate, tristeyl phosphate, trioleyl phosphate, triphenyl phosphite, tris tridecyl phosphite (tris-tridecyl phosphite) , Dibutyl hydrogen phosphite, dibutyl-butyl phosphonate, di (2-ethylhexyl) phosphonate, 2-ethyl Hexyl-2-ethylhexyl phosphonate, methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl Dibutyl acid phosphate, monobutyl acid phosphate, octyl acid phosphate, dioctyl phosphate, isodedecyl phosphate, monoisodecyl phosphate monoisodecyl phosphate) and decanol acid phosphate.

In addition, volatile organic compounds such as glycerin, trimethylolpropane, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol may be used as the softening agent, and lower alkyl ethers, lower fatty acid esters, and higher esters thereof may also be used. Fatty acids, esters thereof, higher fatty alcohols or esters thereof may also be used.

As described above, depending on the form of the photoresist composition, a volatile organic material may be used within a range in which the coating property is not impaired, and preferably, the photoresist composition and the plasticizer are used in a 99: 1 to 90:10 weight ratio.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.                     

Examples 1 to 6 and Comparative Example 1

Next, as shown in Table 1, a negative liquid photoresist was prepared, dried after spin coating, and developed after exposure using Kolon artwork without a neomask, followed by ZEISS laser scanning microscope (Laser). The 1/1 resolution was measured using Scanning Microscope.In the 1/1 resolution measurement, the exposed part is completely attached to the copper layer without damage, and the unexposed part is cleanly removed by the developer and the copper plate Read the value of this fully exposed state.

Workshop temperature: 23 ± 2 ℃

PCB base size: 600mm × 400mm

Drying: 110 ℃, dried for 10 minutes

Coating thickness: 10 micron

Parallel light exposure machine: Perkin-ElmerTM OB7120 (5kW)

Exposure dose: The exposure dose under the artwork and the exposure machine Myler film.

Sensitivity: 21 steps

Artwork: High resolution artwork without protective neomask

Developer: 1.0 wt% Na ₂ CO ₃

Temperature: 30 ± 1 ℃

Break point: 50%                     

Developer spray pressure: 1.0kgf / cm ²

Table 1

ingredient Product name (or ingredient name) Example Comparative example One 2 3 4 5 6 One Base polymer  Acrylic ester polymer 25.0 28.0 25.0 28.0 25.0 28.0 25.0 Photopolymerization initiator                                          Benzophenone (Aldrich Chemical) 2.0 1.5 2.0 1.5 2.0 1.5 2.0 4,4- (bisdiethylamino) benzophenone (Aldrich Chemical) 1.5 1.0 1.5 1.0 1.5 1.0 1.5 additive Toluenesulfonic Acid Monohydrate (Aldrich Chemical) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Diamond Green GH (Japan Hodogaya Co.) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Photopolymerization monomer APG-400 (Miwon Corporation) 7.6 4.8 7.6 4.8 7.6 4.8 8.0 BPE-500 (Miwon Corporation) 11.4 7.2 11.4 7.2 11.4 7.2 12.0 solvent 1-methoxy-2-propanol (Aldrich Chemical, 99%) 50.0 48.0 50.0 48.0 50.0 48.0 50.0 Melamine resin a 1.0 8.0 - - - - - b - - 1.0 8.0 - - - c - - - - 1.0 8.0 - Acrylic ester polymer: An acrylic ester polymer dissolved in 1-methoxy-2-propanol solvent, having a glass transition temperature of 100 to 150 ° C, an acid value of 40 to 150 mgKOH / g, and a weight average molecular weight of 20,000 to 60,000. APG-400: Polypropylene glycol diacrylate BPE-500: Bisphenol A epoxy dimethacrylate melamine resin a-R ₁ to R ₆ is -CH ₂ OC ₆ H ₁₃ Formula 1 Compound melamine resin b-R ₁ to R ₆ is -CH ₂ OCH ₃ in a compound of formula I melamine resin c - R _1, R ₃ and R ₅ are -CH ₂ OCH _3, and, R _2, R ₄ and R ₆ is -CH ₂ OC ₄ H ₉ in formula (1) compound

Table 2

Example Comparative example One 2 3 4 5 6 One Exposure amount (mJ / ㎠) 110 105 110 105 110 110 120 Sensitivity 7 7 7 7 7 7 7 1/1 Resolution (μm) 17 17 18 17 18 18 20 Fine wire adhesion (㎛) 14 15 14 15 14 14 16 Minimum development time (seconds) 15 15 16 15 16 16 15

From the results of Table 1, the same sensitivity, i.e., exposure with varying amounts of light in seven stages, showed better resolution even at lower light levels than Comparative Example 1 in Examples 1 to 6, and as a result, the resist was highly sensitive. Able to know. In addition, it can be seen that the fine wire adhesion can be realized in the case of Examples 1 to 6 as compared to Comparative Example 1 in the case of low value.

As described in detail above, according to the present invention, in addition to the base polymer, the photopolymerization monomer, the photopolymerization initiator, and the additive, the composition containing the melamine resin can increase the efficiency of the photopolymerization initiator by the amino group of melamine without increasing the amount of the photopolymerization initiator. The resist can be highly sensitive, and the amount of photopolymerizable monomer can be reduced by lowering the glass transition temperature of the base polymer, thereby realizing a highly sensitive microcircuit.

Claims (3)

In the negative liquid photoresist composition comprising a base polymer, a photopolymerization monomer, a photopolymerization initiator, an additive and a solvent, The negative liquid photoresist composition, characterized in that it further comprises 1 to 10% by weight of the total resin composition of the melamine resin represented by the following formula (1). Formula 1

In the above formula, R ₁ to R ₆ are the same as or different from each other, and are represented by -CH ₂ OR ₇ , and R ₇ is an alkyl group having 1 to 6 carbon atoms. The method of claim 1, wherein the base polymer is an acrylic ester polymer dissolved in 1-methoxy-2-propanol solvent, the glass transition temperature is 100 to 150 ℃, the acid value is 40 to 150 mgKOH / g, the weight average molecular weight is Negative liquid photoresist composition, characterized in that 20,000 to 60,000. The negative type liquid photo according to claim 1, wherein the content of the photopolymerization monomer is 10 to 40% by weight in the total composition, and the content of the photopolymerization initiator is 1 to 20 parts by weight based on 100 parts by weight of the total amount of the base polymer and the photopolymerization monomer. Resist composition.