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
2003-02-04
2004-10-19
Schilling, Richard L. (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
C430S910000, C522S172000, C522S176000, C522S186000, C526S279000, C526S312000, C526S323100
Reexamination Certificate
active
06806032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a negative-type photosensitive resin composition. More specifically, it relates to a negative-type photosensitive resin composition and the Michael addition reaction product to be used for producing the composition. The present invention can advantageously be used in a wide variety of technical fields such as those of photo masks for etching use in the fabrication of CRT shadow masks, and lead frames for the mounting of IC chips; phosphor patterning of CRT; and further those of photosensitive resin plates, dry films, aqueous photosensitive paints, and aqueous photosensitive adhesives.
2. Description of the Related Art
Heretofore, in the manufacture of shadow masks and aperture grills for a cathode ray tube (CRT), and lead frames for the mounting of IC chips, a chrome-based photosensitive resin composition, such as a casein/chrome-based water-soluble photosensitive resin composition or a polyvinylalcohol (PVA)/chrome-based water-soluble photosensitive resin, has been used as a photoresist mask to be used in the process of etching a metal substrate. A PVA/chrome-based water-soluble photosensitive resin has also been used as a photoresist for use in phosphor patterning of CRT in a dot or stripe pattern on a transparent panel.
Specifically, for example, in the process of manufacturing a CRT shadow mask, a long metal thin plate, approximately 0.1-0.3 mm in thickness, made of 42 alloy (a nickel content of 42%), invar material (a nickel content of 36%), low carbon aluminum killed steel, or the like, is used as a substrate. Both surfaces of the substrate are defatted and washed with water, and then a photosensitive resin composition, which is generally a casein/ammonium dichromate based water-soluble photosensitive resin composition, is applied on both surfaces of the substrate, followed by drying, thereby to form a coating film. After that, a mask pattern having an objective image (pattern) to be formed is brought into close contact with the coating film, and then be exposed the double-sided film-formed substrate, covered with the mask pattern each, to light emitted from an exposure device such as an extra-high pressure mercury lamp. At that time, the masks on both side of the substrate be aligned such that the images (patterns) thereof are in register with each other. After the exposure to light, the substrate is developed using water to form patterns. Subsequently, the substrate with the patterns is dipped into a chromic anhydride solution, then washed with water. After washing, the patterned coating film is subjected to hardening by burning, thereby to form a cured photoresist pattern with increased etching-resistance. Then, an exposed or a photoresist-uncovered area of the substrate is etched with an etching solution of ferric chloride or the like (acidic etching) to form a plurality of pores through which electron beams be transmitted. After that, the photoresist pattern is stripped away, and then the substrate is cut into pieces to obtain shadow masks.
In the phosphor patterning of CRT, a phosphor (e.g., a blue phosphor) with particle sizes of ranging from several micrometers to ten-plus micrometers in diameter is dispersed and suspended in an aqueous PVA/ammonium dichromate mixed solution to obtain a slurry. Subsequently, the front surface portion (panel) of a CRT is turned in a slanting posture and said slurry is then introduced into the inner side of the panel so as to be uniformly applied, followed by drying to form a coating film. After that, the shadow mask manufactured by the above-mentioned method is attached on the panel, and then exposed to light from an extra-high pressure mercury lamp being located at the position onto which an electron gun will be placed after the completion of the CRT. Corresponding portions of the coating film to an aperture (a beam-passing opening) of the shadow mask is exposed to light. In the exposed portions of the coating film, hexavalent chromium is reduced into trivalent chromium and is coordinated with PVA, which resulted in the exposed portions be insolubilized (photo-cured). After the exposure to light, development with hot water is performed, whereby to form photo-cured phosphor patterns. In the case of a color CRT, other two additional photo-cured phosphor patterns (e.g., red and green) are respectively also formed as the same manner as described above. An extra-high pressure mercury lamp is placed at a position corresponding to an electron gun for each color.
The dichromate-containing water-soluble photosensitive resin composition to be used in the fabrication of these electronic parts is capable of forming a pattern having excellent properties of resolution, resistance to etching, and so on, although there are some disadvantages: a dark reaction is apt to occur and is strongly affected by a temperature and a humidity, whereby changes or variations in sensitivity may also occur; stability deteriorates with time and poor preservation stability is exhibited; and dichromateit is a noxious heavy metal salt, so the waste fluid processing be very complicated.
In particular, in recent years, environmental issues are pointed out more strongly than ever before, it is imperative to develop a non-chrome based water-soluble photosensitive resin composition free-from any chrome-based compound, instead of a conventional chrome-based water-soluble photosensitive resin composition containing a noxious heavy metal.
Various kinds of non-chrome based photosensitive resin compositions have been proposed until now.
The typical non-chrome based photosensitive resin compositions used as masks for etching use include (i) a casein-based photosensitive resin composition, (ii) a polyvinyl alcohol-based (PVA) photosensitive resin composition, and (iii) a photosensitive composition obtained by a ring-opening addition between a carboxyl of the side chain of a polymer or an oligomer and an epoxy-containing compound having ethylenic double bonds to introduce the ethylenic double bonds into the side chain of the polymer (oligomer).
Examples of the casein-based photosensitive resin composition described in item (i) above include a composition comprising casein and an azide compound (disclosed in JP-41-7100B), a composition comprising casein, an azide graft polymer, and naphthoquinone diazide sodium sulfonate (disclosed in JP-7-244374A and JP-8-34898A), and a compound prepared by adding organic acid calcium to a composition comprising casein and a water-soluble photosensitive material (disclosed in JP-11-119420A). However, casein tends to be perishable, therefore it should be carefully managed. Casein is coordinated with phosphor to form gel, it is not suitable for a photoresist for phosphor slurry.
Examples of the PVA-based photosensitive resin composition described in item (ii) above include a composition prepared by graft-copolymerizing PVA and vinyl monomer or carrying out addition reaction of glycidyl methacrylate into PVA, followed by adding a photosensitive component such as a tetrazonium salt, a diazo compound, or a diazo resin into the prepared PVA-based resin (disclosed in JP-44-28725B), a composition obtained by reacting PVA with a styryl pyridinium salt containing a formyl (disclosed in JP-55-23163A), and a composition comprising PVA and a condensed diazonium salt (disclosed in JP-56-42859B). However, each of these compositions is inferior to water resistance because of having hydroxyl groups in its PVA structure each. Such a composition in which a high proportion of an aromatic compound is contained, such as a diazide compound, a diazo resin, or a styryl pyridinium salt, is unsuitable for a phosphor slurry, because in ashing process for burning the photoresist off, a large amount of tarry fraction will remain at temperatures of about 400° C. without being burned off.
Proposed examples of the composition described in item (iii) have an excellent resistance to etching, and are disclosed in JP-47-19901A, JP-48-74594A, JP-49-37701A, JP-54-12331B, JP-3-172301A, JP-9-80748A,
Kudo Tomoya
Obata Takekazu
Takanashi Hiroshi
Schilling Richard L.
Tokyo Ohka Kogyo Co. Ltd.
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