U.S. patent application number 10/094264 was filed with the patent office on 2003-03-27 for insulating paste composition for rib formation and method of rib pattern formation.
This patent application is currently assigned to Tokyo Ohka Kogyo Co., Ltd., a Japan corporation. Invention is credited to Nakazato, Syunji, Nishimura, Hiroyuki, Obiya, Hiroyuki, Sato, Hiromitsu.
Application Number | 20030059543 10/094264 |
Document ID | / |
Family ID | 13455731 |
Filed Date | 2003-03-27 |
United States Patent
Application |
20030059543 |
Kind Code |
A1 |
Nakazato, Syunji ; et
al. |
March 27, 2003 |
Insulating paste composition for rib formation and method of rib
pattern formation
Abstract
An insulating paste composition for rib formation which
comprises an insulating material, an organic binder, a
light-absorbing substance, and an organic solvent. A rib pattern is
formed by sandblasting an insulating layer formed of the
composition using a lithographically formed resin pattern mask. The
composition forms an antireflective insulating layer which can
provide a rib pattern excellent in cross-sectional contour and
dimensional precision.
Inventors: |
Nakazato, Syunji; (US)
; Sato, Hiromitsu; (US) ; Obiya, Hiroyuki;
(US) ; Nishimura, Hiroyuki; (US) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
45 ROCKEFELLER PLAZA, SUITE 2800
NEW YORK
NY
10111
US
|
Assignee: |
Tokyo Ohka Kogyo Co., Ltd., a Japan
corporation
|
Family ID: |
13455731 |
Appl. No.: |
10/094264 |
Filed: |
March 8, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10094264 |
Mar 8, 2002 |
|
|
|
09526605 |
Mar 16, 2000 |
|
|
|
6372292 |
|
|
|
|
Current U.S.
Class: |
427/385.5 ;
427/256 |
Current CPC
Class: |
G02F 1/13394 20130101;
G03F 7/0007 20130101; G03F 7/0047 20130101; H01J 2217/492 20130101;
H01J 9/242 20130101 |
Class at
Publication: |
427/385.5 ;
427/256 |
International
Class: |
B05D 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 1999 |
JP |
11-71265 |
Claims
What is claimed is:
1. An insulating paste composition for rib formation which
comprises an insulating material, an organic binder, a
light-absorbing substance, and an organic solvent.
2. The insulating paste composition for rib formation according to
claim 1, which comprises 50 to 95% by weight of the insulating
material, 0.5 to 15% by weight of the organic binder, 0.1 to 15% by
weight of the light-absorbing substance, and 1 to 50% by weight of
the organic solvent.
3. The insulating paste composition for rib formation according to
claim 1, wherein the light-absorbing substance is at least one
selected from the group consisting of benzophenone dyes, azo dyes,
polyene dyes, quinoline dyes, aminoketone dyes, anthraquinone dyes,
benzotriazole dyes, and cyanoacrylate dyes.
4. The insulating paste composition for rib formation according to
claim 1, wherein the insulating material is at least one selected
from the group consisting of Al.sub.2O.sub.3, PbO, B.sub.2O.sub.3,
SiO.sub.2, ZnO, MgO, and SnO.sub.2.
5. The insulating paste composition for rib formation according to
claim 4, wherein the insulating material further comprises a
low-melting glass powder having a softening point of approximately
from 350 to 600.degree. C.
6. A method of forming a rib pattern comprising coating a substrate
with an insulating paste composition which comprises an insulating
material, an organic binder, a light-absorbing substance, and an
organic solvent, drying the paste composition to form a rib-forming
insulating layer, forming a resin pattern on the rib-forming
insulating layer by use of a photosensitive resin composition, and
etching the insulating layer by sandblasting using the resin
pattern as a mask.
7. The method of forming a rib pattern according to claim 6,
wherein the insulating paste composition comprises 50 to 95% by
weight of the insulating material, 0.5 to 15% by weight of the
organic binder, 0.1 to 15% by weight of the light-absorbing
substance, and 1 to 50% by weight of the organic solvent.
8. The method of forming a rib pattern according to claim 6,
wherein the light-absorbing substance is at least one selected from
the group consisting of benzophenone dyes, azo dyes, polyene dyes,
quinoline dyes, aminoketone dyes, anthraquinone dyes, benzotriazole
dyes, and cyanoacrylate dyes.
9. The method of forming a rib pattern according to claim 6,
wherein the insulating material is at least one selected from the
group consisting of Al.sub.2O.sub.3, PbO, B.sub.2O.sub.3,
SiO.sub.2, ZnO, MgO, and SnO.sub.2.
10. The method of forming a rib pattern according to claim 9,
wherein the insulating material further comprises a low-melting
glass powder having a softening point of approximately from 350 to
600.degree. C.
Description
FIELD OF THE INVENTION
[0001] This invention relates to an insulating paste composition
for forming ribs in the manufacture of various electronic displays
and to a method of rib formation using the composition. More
particularly, it relates to an insulating paste composition capable
of forming a rib pattern excellent in dimensional precision and
cross-sectional contour and a method of rib pattern formation using
the same.
BACKGROUND OF THE INVENTION
[0002] Production of various electronic displays, such as
semiconductor or liquid crystal displays and plasma display panels,
generally includes rib formation on a substrate to provide spacers
between electrodes or cell partitions. Ribs are formed by, for
example, a method comprising applying an insulating paste
composition comprising an insulating material, an organic binder
and an organic solvent directly to a substrate by screen printing
or with a roll coater to form a rib pattern or a method comprising
forming a green sheet of the insulating paste composition and
transferring the green sheet onto the substrate. However, the
conventional rib formation methods involve complicated steps and
have great difficulty in forming an excellent rib pattern having
rectangular cross-sectional contour with high precision. Further,
the methods are not suitable for forming a fine line pattern,
failing to cope with the latest fine processing techniques. To
solve this problem, a lithographic technique has been proposed,
which comprises applying an insulating paste composition to a
substrate to a desired thickness, forming thereon a pattern mask of
a photosensitive resin, and removing the exposed area of the
insulating paste composition layer as a protective mask by
sandblasting. The problem associated with the known lithographic
technique is that, where the insulating paste composition has a
high reflectance, the dimensional precision of the lithographically
formed pattern mask is adversely affected by the reflection of
light at the insulating paste composition at the formation of the
photosensitive resin pattern. The ribs formed by the lithographic
technique have not only low dimensional precision but a poor
cross-sectional contour, which are particularly problematical in
the production of plasma display panels (hereinafter "PDP") in
which white ribs are formed for improving image brightness and have
made it difficult to manufacture sufficiently practical PDP.
[0003] It has therefore been demanded to develop a method of
producing PDP in which a rib pattern having an excellent contour
and a high dimensional precision can be formed even with an
insulating paste composition containing an insulating material
having a high reflectance.
SUMMARY OF THE INVENTION
[0004] In the light of the above-mentioned circumstances, the
present inventors have conducted extensive studies and found as a
result that an insulating paste composition containing a
light-absorbing substance provides a rib pattern with excellent
contour and dimensional precision even where the composition
comprises an insulating material having a high reflectance.
[0005] An object of the present invention is to provide an
insulating paste composition which forms a rib pattern excellent in
cross-sectional contour and dimensional precision.
[0006] Another object of the invention is to provide a convenient
method of forming a rib pattern excellent in cross-sectional
contour and dimensional precision.
[0007] The invention provides an insulating paste composition for
rib formation which comprises an insulating material, an organic
binder, a light-absorbing substance, and an organic solvent. The
invention also provides a method of rib formation comprising using
the insulating paste composition.
[0008] The rib-forming insulating paste composition of the present
invention forms a rib-forming layer which prevents irregular
reflection from the surface thereof when a photosensitive resin
layer provided thereon is irradiated with active rays. As a result,
the photosensitive resin layer is allowed to form a resin pattern
having a rectangular cross-sectional contour. Sandblasting the
rib-forming layer using the resin pattern as a mask provides a rib
pattern excellent in cross-sectional contour and dimensional
precision. The composition of the invention is especially effective
in the formation of a white rib pattern having a high reflectance.
Firing the rib pattern gives sharp and highly precise ribs.
[0009] According to the rib formation method of the invention a rib
pattern can be formed easily at a reduced production cost.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The insulating material which can be used in the invention
is made up of inorganic substances, such as Al.sub.2O.sub.3, PbO,
B.sub.2O.sub.3, SiC.sub.2, ZnO, MgO, and SnO.sub.2. It is preferred
to use low-melting glass powder that functions as a binder on
firing in combination with these inorganic substances particularly
where the rib formation involves a firing step as in the
manufacture of PDP. The low-melting glass powder includes
low-melting lead glass and low-melting zinc glass, whose softening
points range approximately from 350 to 600.degree. C. A combination
of alumina powder and low-melting lead glass powder is a
particularly preferred insulating material.
[0011] The organic binder and the organic solvent are used for
making the insulating material into paste having film-forming
properties. Any organic binders and solvents can be used as long as
they are inert to the insulating material and burnt up on firing.
Examples of suitable organic binders include cellulose series
polymers, such as nitrocellulose, acetyl cellulose, ethyl
cellulose, carboxymethyl cellulose, hydroxyethyl cellulose,
hydroxypropyl cellulose, methyl cellulose, ethylhydroxy cellulose,
and carboxymethylethyl cellulose; natural rubber, polybutadiene,
chloroprene rubber, acrylic rubber, and isoprene synthetic rubbers,
a natural high polymer such as a cyclized rubber, and a synthetic
polymer such as polyethylene, polypropylene, polymethyl acrylate,
polymethyl methacrylate, polystyrene, polyvinyl alcohol, polyvinyl
butyral, polyvinyl acetate, polyester, polycarbonate,
polyacrylonitrile, polyvinyl chloride, polyamine, and polyurethane.
These polymers may be used either individually or a combination
thereof, or in the form of copolymers.
[0012] The organic solvents are chosen from among those capable of
uniformly dissolving or dispersing the selected organic binder.
Examples of useful solvents are hydrocarbons, such as toluene and
xylene; alcohols, such as methanol, ethanol, 2-propanol, and
.alpha.-terpineol; ketones, such as acetone, methyl ethyl ketone,
methyl isobutyl ketone, cyclohexanone, and isophorone; esters, such
as methyl acetate, ethyl acetate, and butyl acetate; ethylene
glycol ethers, such as ethylene glycol monomethyl ether, ethylene
glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene
glycol monomethyl ether acetate, ethylene glycol monoethyl ether
acetate, and ethylene glycol monobutyl ether acetate; and
diethylene glycol ethers, such as diethylene glycol monomethyl
ether, diethylene glycol monoethyl ether, diethylene glycol
monobutyl ether, diethylene glycol monomethyl ether acetate,
diethylene glycol monoethyl ether acetate, and diethylene glycol
monobutyl ether acetate. These solvents may be used either
individually or as a mixture of two or more thereof.
[0013] The light-absorbing substance which can be incorporated into
the insulating paste composition includes dyes which absorb light
used for exposing a photosensitive resin composition forming a
pattern mask, i.e., the light within the sensitive wavelength
region of the photosensitive component of the photosensitive resin
composition, prevent generation of stationaty waves or irregular
reflection on the surface of the insulating paste composition layer
formed, and have no adverse influences on the fluorescence
characteristics of PDP. Dyes satisfying these requirements include
benzophenone dyes, azo dyes, polyene dyes, quinoline dyes,
aminoketone dyes, anthraquinone dyes, benzotriazole dyes, and
cyanoacrylate dyes. Specific examples of suitable dyes are Crystal
Violet (benzophenone dye produced by BASF), Oil Yellow 105 (azo dye
produced by Orient Kagaku Kogyo K.K.), Diaresin Red G
(anthraquinone dye produced by Mitubishi Chemical Corporation),
Latyl Yellow 3G (quinoline dye produced by E.I. de Pont), and
Duranol Brilliant Orange TG (aminoketone dye produced by ICI).
These dyes may be used either individually or as a combination of
two or more thereof.
[0014] The insulating paste composition of the invention may
contain a plasticizer, if desired.
[0015] A preferred formulation of the insulating paste composition
comprises 50 to 95% by weight of the insulating material, 0.5 to
15% by weight of the organic binder, 0.1 to 15% by weight of the
light-absorbing substance, 1 to 50% by weight of the organic
solvent, and from 0 up to 15% by weight of the plasticizer. If the
amount of the light-absorbing substance is less than 0.1%, the
effect on reflection prevention is insubstantial. If it exceeds
15%, too much light would be absorbed, making it difficult to form
a satisfactory pattern.
[0016] Rib formation with the insulating paste composition of the
present invention can be carried out, for example, as follows. The
pasty composition is applied to a substrate, such as a glass plate,
and dried to form a rib-forming layer. The rib-forming layer is
coated with a photosensitive resin composition (hereinafter
described in detail) followed by drying to form a photosensitive
resin layer. The photosensitive resin layer may be formed by once
forming a dry film having a photosensitive resin between a flexible
supporting film and a release film, removing the release film, and
adhering the dry film onto the rib-forming layer by pressing. The
photosensitive resin layer is irradiated with active rays through a
mask having a prescribed pattern and developed to form a resin
pattern. The rib-forming layer of the exposed area is etched by
sandblasting. Removal of the resin pattern with a remover
containing sodium hydroxide, potassium hydroxide, periodic acid,
sodium periodate, an organic alkali, etc., gives a rib pattern
formed on the substrate. In the production of PDP, the rib pattern
thus obtained is preferably fired at 500.degree. C. or higher.
Abrasives used for sandblasting include fine particles having a
particle size of about 1 to 500 .mu.m of glass beads, SiC,
SiO.sub.2, Al.sub.2O.sub.3, ZrO.sub.2, organic plastics, and the
like.
[0017] The photosensitive resin composition which can be used for
resin pattern formation is not particularly limited as long as it
is easily removable by firing or with a remover. For example, the
photosensitive resin composition described in JP-A-9-127692 (the
term "JP-A" as used herein means an unexamined published Japanese
patent application) is preferred, which comprises a
photopolymerizable urethane (meth)acrylate compound having at least
two acryloyl or methacryloyl groups, an alkali-soluble polymer, and
a photopolymerization initiator. The photopolymerizable urethane
(meth)acrylate compound having at least two acryloyl or
methacryloyl groups includes a reaction product obtained by the
reaction between an isocyanate-terminated compound (obtainable by
the reaction between a diol compound and a diisocyanate compound)
and a (meth)acrylate compound having a hydroxyl group. In
particular, a urethane acrylate having at least three urethane
bonds per molecule is preferred. The alkali-soluble polymer
includes acrylic acid resins, methacrylic acid resins, acrylic or
methacrylic acid copolymers, and alkali-soluble cellulosic resins
such as carboxymethyl cellulose and cellulose acetate phthalate.
Comonomers of the acrylic acid or methacrylic acid copolymers
include fumaric acid, maleic acid, crotonic acid, cinnamic acid,
methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl
methacrylate, butyl acrylate, butyl methacrylate, isobutyl
acrylate, isobutyl methacrylate, monomethyl fumarate, monoethyl
fumarate, monopropyl fumarate, monomethyl maleate, monoethyl
maleate, monopropyl maleate, and sorbic acid. Cellulose compounds
obtained by the reaction between a partial acetic ester of
cellulose and a di- or tricarboxylic acid, e.g., succinic acid,
adipic acid or trimellitic acid, are also preferred.
[0018] The photopolymerization initiator includes benzophenone and
its derivatives, such as 4,4'bis(dimethylamino)benzophenone and
3,3-dimethyl-4-methoxybenzophenone; anthraquinone and its
derivatives, such as 2-methylanthraquinone, 2-ethylanthraquinone,
t-butylanthraquinone, and 1-chloroanthraquinone; benzoin and its
alkyl ethers, such as benzoin methyl ether, benzoin ethyl ether,
and benzoin propyl ether; acetophenone and its derivatives, such as
2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone,
2-hydroxy-2-methylpropiophenone,
4'-isopropyl-2-hydroxy-2-methylpropiophe- none, and
2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone;
thioxanthone derivatives, such as 2-chlorothioxanthone,
diethylthioxanthone, isopropylthioxanthone, and
diisopropylthioxanthone; benzil, 2,4,6-(trihalomethyl)-s-triazines,
2-(o-chlorophenyl)-4,5-dipheny- limidazolyl dimer,
9-phenylacridine, 1,7-bis(9-acridinyl)heptane,
1,5-bis(9-acridinyl)pentane, 1,3-bis(9-acridinyl)propane,
dimethylbenzyl ketal, trimethylbenzoyldiphenylphosphine oxide,
tribromomethylphenyl sulfone,
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and so
forth. These photopolymerization initiators can be used either
individually or as a combination of two or more thereof.
[0019] A preferred photosensitive resin composition comprises 50 to
90% by weight, based on the total composition, of the
photopolymerizable urethane (meth)acrylate compound having at least
two acryloyl or methacryloyl groups, 5 to 50% by weight, based on
the total composition, of the alkali-soluble polymer, and 0.1 to
20% by weight, based on the total amount of the urethane
(meth)acrylate and the alkali-soluble polymer, of the
photopolymerization initiator.
[0020] The present invention will now be illustrated in greater
detail with reference to Examples, but it should be understood that
the invention is not construed as being limited thereto. Unless
otherwise noted, all the parts and percents are by weight.
EXAMPLE 1
[0021] A rib-forming insulating paste composition was prepared from
100 parts of white low-melting glass frit containing PbO, 2 parts
of ethyl cellulose, 5 parts of dibutyl phthalate (plasticizer), 20
parts of .alpha.-terpineol, and 5 parts of Oil Yellow 105 (azo dye
available from Orient Kagaku Kogyo K.K.) by kneading in a
three-roll mill.
[0022] The insulating paste composition was applied to a soda glass
plate by screen printing and dried to form a rib-forming layer
having a thickness of 150 .mu.m. The rib-forming layer was
laminated with a dry film resist of a photosensitive resin
composition, ORDYL BF-703 supplied by Tokyo Ohka Kogyo Co., Ltd.
The photosensitive resin film was exposed through a test mask to
light from a 3.5 W ultrahigh pressure mercury lamp at an intensity
of 200 mJ/cm.sup.2 and spray-developed with a 0.2% sodium carbonate
aqueous solution to provide a cured resin pattern. The resin
pattern had a rectangular cross-sectional contour with high
sharpness and a high dimensional precision, showing a dimensional
difference as small as 0.2 .mu.m from the test mask.
[0023] The rib-forming layer thus exposed was etched by
sandblasting with glass beads #800 (available from Toshiba
Ballotini Co., Ltd.) to form a rib pattern faithful to the test
mask pattern with a high dimensional precision and having a
rectangular cross-sectional contour. The substrate was immersed in
a 12% monoethanolamine aqueous solution to remove the resin layer
and fired at 520.degree. C. The resulting substrate had no burnt
residue, and the rib pattern showed high dimensional precision and
an excellent contour.
EXAMPLE 2
[0024] A rib-forming insulating paste composition was prepared in
the same manner as in Example 1, except for replacing Oil Yellow
105 with C. I. Acid Black 123 (succinate dye, available from Orient
Kagaku Kogyo K.K.). The resulting paste composition was applied to
soda glass and dried in the same manner as in Example 1 to form a
rib-forming layer, and a resin pattern mask was formed thereon in
the same manner as in Example 1. The resin pattern mask had a
rectangular cross-sectional contour with high sharpness and a high
dimensional precision, showing a dimensional difference of 0.3
.mu.m from the test mask.
[0025] The rib-forming layer thus exposed was etched by
sandblasting, the resin layer was removed, and the substrate was
fired at 520.degree. C. in the same manner as in Example 1. The
resulting substrate had no burnt residue, and the rib pattern
showed a high dimensional precision and an excellent contour.
COMPARATIVE EXAMPLE 1
[0026] A resin pattern was formed in the same manner as in Example
1, except for omitting-Oil Yellow 105 from the rib-forming
insulating paste composition. The resulting resin pattern had poor
sharpness with a dimensional difference of 0.51 .mu.m from the test
mask.
[0027] While the invention has been described in detail and with
reference to specific examples thereof, it will be apparent to one
skilled in the art that various changes and modifications can be
made therein without departing from the spirit and scope
thereof.
* * * * *