Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2002-04-30
2004-06-15
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S285100, C430S911000, C430S910000, C430S916000, C430S271100
Reexamination Certificate
active
06749994
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a photosensitive insulating paste composition and a photosensitive film made therefrom. More particularly, the invention relates to a photosensitive insulating paste composition comprising an organic component and an inorganic powder which has high sensitivity for precise patterning even when formed into a thick film and a photosensitive dry film made from the composition.
BACKGROUND OF THE INVENTION
Thick film multilayer circuit boards and various display panels have been produced by thick film screen printing techniques in which a photocuring insulating paste containing inorganic particles is screen printed on a substrate to form a pattern or photolithographic techniques in which a photocuring insulating paste composition is applied to a substrate, irradiated with ultraviolet rays, etc., and developed to form a relief pattern on the substrate. In particular, considerable attention has been devoted to plasma display panels (PDPs) for their relatively simple structure, large screen capability, self-luminescent high display quality, and color feasibility. A large number of proposals on PDPs have been made seeking for a larger scale and higher precision. APDP is a flat display panel composed a pair of glass substrates between which a vast number of cells are arrayed, being separated by barrier ribs made of an insulating material. Each cell, acting as a pixel, contains a phosphor, which is excited by ultraviolet rays generated by a plasma discharge to emit visible light. Electrodes, resistors, dielectrics, etc. for generating plasma are provided on the substrates and in the cells. In order to increase the precision of PDPs it is necessary to form the elements constructing the panel, i.e., barrier ribs, electrodes, resistors, dielectrics, phosphors, a color filter array, and a black matrix (hereinafter referred to as barrier ribs, etc.) with high precision. A higher precision patterning technique is still demanded therefor. Conventional thick film screen printing techniques, which involve repetition of printing a paste composition, have poor pattern position accuracy and difficulty in forming highly precise barrier ribs, etc. With photolithographic techniques, the film for forming barrier ribs, etc. is too thick for assuring sufficient photosensitivity over the whole thickness, which has been a bar to realization of high precision patterning. Besides, development involves use of expensive organic solvents such as trichloroethane, which not only leads to an increase of production cost but gives rise to such issues as environmental pollution and harm to human bodies. In an attempt to provide solutions for the problems associated with the development with an organic solvent, JP-A-63-265238 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a water-developable photocuring insulating paste composition comprising a water-soluble cellulose such as methyl cellulose, a photopolymerizable polymer, a photopolymerization initiator, and an inorganic powder. However, the proposed composition has insufficient resistance against development so that the image areas are liable to be dissolved on developing. Moreover, because the composition is patternwise applied by screen printing, the pattern position accuracy is poor. The composition cannot therefore be seen as capable of high precision patterning in fabricating barrier ribs, etc.
SUMMARY OF THE INVENTION
In the light of these circumstances, the inventors of the present invention have conducted extensive investigations. They have found as a result that a photosensitive insulating paste composition comprising a water-soluble cellulose derivative, a photopolymerizable monomer, an acrylic resin having a hydroxyl group, a photopolymerization initiator, and an inorganic powder is easily aqueous- or alkaline-developable, free from the organic solvent problems such as environmental pollution or harm to human bodies, and exhibits high sensitivity enough to be formed into a thick film which is fit for fabricating barrier ribs, etc. and thick film multilayer circuits with high precision. The present invention has been reached based on this finding.
An object of the present invention is to provide a photosensitive insulating paste composition which is easily aqueous- or alkaline-developable, capable of forming a thick and yet highly sensitive photosensitive insulating paste composition layer, and capable of forming a pattern with high precision.
Another object of the invention is to provide a photosensitive dry film made of the above-described photosensitive insulating paste composition.
The above objects of the invention are accomplished by a photosensitive insulating paste composition comprising an organic component comprising the components of (A) a water-soluble cellulose derivative, (B) a photopolymerizable monomer, (C) an acrylic resin having a hydroxyl group, and (D) a photopolymerization initiator and an inorganic powder and a photosensitive film made of the composition.
DETAILED DESCRIPTION OF THE INVENTION
Containing a water-soluble cellulose derivative as a binder resin, the photosensitive insulating paste composition of the invention exhibits higher transmittances of radiations for exposure, such as ultraviolet radiation, excimer laser beams, X-rays, and electron beams, and capability of forming patterns with higher precision than conventional photosensitive insulating paste compositions containing acrylic resin binders.
Any known water-soluble cellulose derivatives can be used as component (A) with no particular limitation. Examples of useful water-soluble cellulose derivatives are carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, ethylhydroxyethyl cellulose, carboxymethylethyl cellulose, and hydroxypropylmethyl cellulose. They may be used either individually or as a mixture of two or more thereof.
The photopolymerizable monomer which can be used as component (B) is not particularly limited, either. Suitable photopolymerizable monomers include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane triacrylate, trimethylolethane trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, glycerol acrylate, glycerol methacrylate, carboepoxy diacrylate; fumaric esters, itaconic esters and maleic esters corresponding to these (meth)acrylic esters.
The acrylic resin having a hydroxyl group which can be used as component (C) includes polymers mainly comprising an acrylic ester monomer and a hydroxyl-containing monomer and, if necessary, other copolymerizable monomers. Suitable acrylic ester monomers include acrylic acid or methacrylic acid esters with monohydric alcohols having 1 to 20 carbon atoms. Suitable hydroxyl-containing monomers include monoesters of glycols having 1 to 10 carbon atoms with acrylic acid or methacrylic acid, such as hydroxymethyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutyl methacrylate, 3-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate; glycerol acrylate, glycerol methacrylate, dipentaerythritol monoacrylate, dipentaerythritol monomethacrylate, &egr;-caprolactone-modified hydroxyethyl acrylate, &egr;-caprolactone-modified hydroxyethyl methacrylate, and epoxy ester compounds such as 2-hydroxy-3-phenoxypropyl acrylate.
Inoue Tomoyuki
Obiya Hiroyuki
Oshio Kiminori
Setsuda Hitoshi
Fish & Richardson P.C.
Huff Mark F.
Lee Sin J.
Tokyo Ohka Kogyo Co. Ltd.
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