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
2000-04-04
2002-06-18
Derrington, James (Department: 1731)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S286100, C430S313000, C430S315000, C430S319000, C156S247000, C156S272200, C264S402000, C264S496000, C427S510000, C427S511000
Reexamination Certificate
active
06406832
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for fabricating ribs of a plasma display panel (PDP). More particularly, the present invention provides a simplified process for fabricating the ribs of a PDP.
2. Description of the Prior Art
Plasma display panels (PDP) are flat panel displays that use a discharge gas to create glowing images on a screen. The PDP has many beneficial characteristics, such as thin, lightweight design, large display sizes and a wide viewing angle.
The PDP has ribs that serve to isolate individual discharge cells from each other, both electrically and optically. The ribs also provide support between the front and rear plates of the PDP. Currently, the fabrication of the ribs of a PDP is the most difficult part of the PDP fabrication process. Hence, improving the rib fabrication process is an important issue in the PDP industry.
Please refer to
FIG. 1
to FIG.
4
.
FIG. 1
to
FIG. 4
are cross sectional diagrams of a prior process for fabricating ribs
12
using a sandblasting method. The prior art PDP (not shown) comprises a transparent plate (not shown) and a glass substrate
10
that is positioned behind the transparent plate. In the sandblasting method shown in
FIG. 1
, solid print of a glass paste is used two or three times to form a glass paste layer
14
onto the glass substrate
10
. Next, a dry film photoresist
16
is layered onto the glass paste layer
14
.
An exposure process is performed to define the pattern of the ribs
12
. The exposure process uses ultraviolet (UV) radiation
20
and a photo-mask
18
to selectively irradiate portions of the photoresist
16
. The irradiated. portions of the dry film photoresist
16
are hardened and thus transmit the pattern of the photo-mask
18
onto the dry film photoresist
16
. As. shown in
FIG. 2
, a development process is carried out to remove the dry film photoresist
16
that hasn't been exposed to the UV radiation
20
. The exposed dry film photoresist
16
remains on the glass paste layer
14
and defines the pattern of the ribs
12
.
As shown in
FIG. 3
, after the development process, a sandblasting process is performed. The exposed dry film photoresist
16
protects the glass paste layer
14
below it. A portion of the glass paste layer
14
not covered by the dry film photoresist
16
is removed by the sandblasting process. Then, as shown in
FIG. 4
, a stripping process removes the remaining dry film photoresist
16
, and a firing process is then performed. The glass substrate
10
is heated to 550° C., which fuses the remaining glass paste layer
14
, for forming the ribs
12
.
The sandblasting method according to the prior art manufactures ribs
12
with narrow width and even height, but some constraints are imposed by using the dry film photoresist
16
. In the sandblasting process, sand is sent at high speed towards the glass substrate
10
, the dry film photoresist
16
must adhere tightly to the glass paste layer
14
. However, the dry film photoresist
16
may peel from the top of the glass paste layer
14
under the friction of the sand blasting process when the adhesion of the dry film photoresist
16
is poor. Moreover, the dry film photoresist
16
needs to be removed completely by a suitable machine after the sandblasting step. Therefore, the dry film photoresist
16
should be stripped from the glass paste layer
14
easily. Hence, adhesion characteristics of the dry film photoresist
16
to the glass paste layer
14
should be considered carefully. In summary, characteristics of the dry film photoresist includes strong adhesion to the glass paste, high resistance against sand blasting, and easy removal after the sandblasting process. However, this complicates the manufacturing process, giving rise to higher costs.
Please refer to FIG.
5
and FIG.
6
. FIG.
5
and
FIG. 6
are schematic diagrams of a prior process for fabricating the ribs
12
of a PDP using a screen printing method. As shown in
FIG. 5
, the screen printing method uses a scraper
22
to print a glass paste
13
through a screen
24
onto a predetermined area of the glass substrate
10
.
As shown in
FIG. 6
, the screen printing steps are repeated six to twelve times to form the glass paste
13
over the glass substrate
10
. The glass paste
13
is stacked until the thickness reaches a predetermined thickness, such as 150 &mgr;m to 200 &mgr;m. Finally, a firing process is employed to heat the glass substrate
10
until the temperature rises to between 50° C. and 600° C. Under such high temperatures, the stacked glass paste
13
fuses to form the ribs
12
.
In the screen printing method, a dry film photoresist is not used and less glass paste is consumed. However, the screen printing method has poor precision control, and this is a disadvantage in the fabrication of high-resolution PDPs. It is very difficult to control with precision a multi-layer printing process, and so the screen printing method is unable to form ribs with a narrow width. The resolution of the PDP cannot, therefore, be further enhanced. Moreover, the complexity of the manufacturing process is proportional to the number of times that the printing process is performed. The multi-layer printing process increases manufacturing time, and also forms ribs
12
with a non-uniform thickness.
SUMMARY OF THE INVENTION
Therefore, a primary objective of the present invention is to provide a method for fabricating ribs of a plasma display panel to solve the above mentioned problems which use the sandblasting method or the screen printing method.
According to the present invention, a method for fabricating ribs of a plasma display panel (PDP) is provided. The PDP comprises a glass substrate. In the method, a solid printing process is first performed to form a first paste layer on the glass substrate. Next, a screen printing process prints a second paste layer onto a first predetermined area of the first paste layer. The second paste layer includes the same rib materials as the first paste layer and a photo-active hardener, such as polyvinyl cinnamate. An exposure process is then employed to activate the photo-active hardener, and causing the second paste layer to be harden. Then, a sandblasting process removes those portions of the first paste layer that are not covered by the second paste layer, the hardened second paste layer acting as a hard mask. Finally, a heating process removes the hardener from the second paste layer and fuses the first paste layer to the second paste layer to form a plurality of ribs.
There is no dry film photoresist used in the aforementioned process, and the printing process is performed only a few times. Thus, the present method simplifies a more complicated process and reduces production time and costs.
These. and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.
REFERENCES:
patent: 3767490 (1973-10-01), Alberts
patent: 4119480 (1978-10-01), Nishi et al.
patent: 4711835 (1987-12-01), Dutour
patent: 5209688 (1993-05-01), Nishigaki et al.
patent: 5814267 (1998-09-01), Sakai et al.
patent: 6043604 (2000-03-01), Horiuchi et al.
Derwent Acc No. 1981-88476, Oct. 1981.
AU Optronics Corp.
Derrington James
Hsu Winston
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