Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-09-30
2002-05-21
Gray, Linda (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S154000, C216S023000, C216S052000, C216S053000, C216S095000, C216S097000, C368S084000, C368S158000, C368S242000, C968S931000
Reexamination Certificate
active
06391137
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing a display device, and specifically relates to a process of thinning a substrate which composes a display device.
2. Description of the Related Art
In recent years, electronic appliances, household electrical appliances, or the like, have been increasingly developed and produced and have been sold in quantity on the market, and not only a TV set but also a VTR, a personal computer, and the like, have also been spread widely among ordinary people. These appliances have grown their performances year by year, and have been indispensable in our modern society as a tool for providing the users with a lot of information as the information society progresses. Many of these appliances are equipped with a display device which serves as information displaying means for accurately transmitting information to the users, and as the display device, a low-profile and lightweight display device has been desired.
For example, Japanese Unexamined Patent Publication JP-A 4-116619 (1992) (JP-B2 2722798), discloses an invention which aims at weight-reduction of liquid crystal display devices. It discloses a method of producing a liquid crystal display device, capable of obtaining a plurality of liquid crystal display devices from a pair of glass substrates, wherein in order to thin the liquid crystal display devices, chemical abrasion is performed in a state of an assembly of the liquid crystal display devices in which the pair of substrates having an area for the plurality of liquid crystal display devices are bonded.
In the following, the prior art will be briefly explained referring to drawings.
FIGS. 12 and 13
show plan and sectional views of an assembly of liquid crystal display devices. (hereinafter described as an assembly of devices) made by bonding a pair of substrates having an area for the plurality of liquid crystal display devices. The assembly of devices A is assembled in the following manner.
At first, in each region of a pair of glass substrate a transparent electrode for display, an orientation film, and the like, (not shown in the drawings) are formed on each device division
6
on a pair of original glass substrates (so-called mother glass substrates)
1
,
2
.
Next, frame-shaped sealing materials
3
for respectively surrounding regions b of the respective in which liquid crystal is to be sealed regions b of the respective device divisions
6
are printed on the surface of one of the original glass substrates, and a periphery sealing material
4
for surrounding all of the device divisions
6
is printed slightly inside the edge of the periphery of the glass substrate. As such an adhesive, an epoxy-resin adhesive which has a high etching selectivity ratio with the original glass substrates
1
,
2
is used. Moreover, each sealing material
3
is printed so that a clearance to become a liquid crystal injection hole
3
a
is left on part thereof, and the periphery sealing material
4
is printed so that a clearance to become a ventilation hole
4
a
is left on part thereof.
Next, the pair of original glass substrates
1
,
2
are stacked on each other so that the respective device divisions
6
are opposed to each other, and the original glass substrates
1
,
2
are adhered to each other via the sealing materials
3
and the periphery sealing material
4
as described above. In this case, a gap between the original glass substrates
1
,
2
is connected with the outside via the liquid crystal injection holes
3
a
provided on parts of the respective sealing materials
3
and the ventilation hole
4
a
provided on part of the periphery sealing material
4
, so that the barometric pressure between the original glass substrates
1
,
2
would not be increased. Therefore, both the original glass substrates
1
,
2
are globally adhered to each other with a uniform gap.
After that, the ventilation hole
4
a
as mentioned above is encapsulated by an encapsulating material
5
such as an epoxy-resin adhesive which has a high etching selectivity ratio with both the original glass substrates
1
,
2
, whereby the assembly of devices A is completed.
After the assembly of devices A is assembled in this way, the assembly of devices A is immersed in an etchant
11
inside an etching tank
10
to etch the outer faces of both the original glass substrates
1
,
2
of the assembly of devices A as shown in FIG.
14
. In this case, an etchant which basically consists of hydrofluoric acid is used as the etchant
11
.
When the assembly of devices A is immersed in the etchant
11
to etch the outer faces of both the original glass substrates
1
,
2
in this way, the thickness of each of the original glass substrates
1
,
2
is reduced from the initial thickness as shown by a dashed line to the thickness as shown by a rigid line in FIG.
14
. Moreover, since etching of the original glass substrates
1
,
2
is performed uniformly all over the outer faces of the substrates, the overall original glass substrates
1
,
2
are thinned uniformly.
Further, when the assembly of devices A is immersed in the etchant
11
, the etchant
11
would enter the gap between the original glass substrates
1
,
2
. However, in the production method as described above, the pair of original glass substrates
1
,
2
are adhered to each other via the periphery sealing material
4
which surrounds all of the device divisions
6
when the assembly of devices A is assembled, the ventilation hole
4
a
provided on part of the periphery sealing material
4
is encapsulated by the encapsulating material
5
, and the sealing material
4
and the encapsulating material
5
are made by an epoxy-resin adhesive, or the like, which has a high etching selectivity ratio with the original glass substrates
1
,
2
. Therefore, it is avoided by the periphery sealing material
4
that the etchant
11
enters the gap between the original glass substrates
1
,
2
.
Therefore, in etching of the outer faces of the original glass substrates
1
,
2
, the inner sides of the respective device divisions
6
, that is, electrode terminal arrays outside the sealing materials
3
and the liquid crystal sealed-in regions b surrounded by the sealing materials
3
would not be subjected to the etchant
11
. As for both the original glass substrates
1
,
2
, although not only the outer faces but also the periphery faces are etched, it is prevented by the periphery sealing material
4
that the etchant
11
enters the gap between the original glass substrates
1
,
2
before the peripheral faces of the glass substrates
1
,
2
are etched to recess inside the inner peripheral face of the periphery sealing material
4
. Therefore, as long as the periphery sealing material
4
as mentioned above is printed slightly inside the edge of the periphery of the substrate and the periphery sealing material
4
is made to have a sufficient width, any problem would not be caused when the peripheral faces of the glass substrates
1
,
2
are etched.
After the outer faces of both the original glass substrates
1
,
2
are etched in this way in a state where the assembly of devices A is assembled, the assembly of devices A is washed immediately to thoroughly eliminate the etchant attached thereon, and thereafter both the original glass substrates
1
,
2
of the assembly of devices A as mentioned above are divided for each device division
6
, with the result that the assembly of devices A is separated into cell members of individual liquid crystal display devices.
After that, a liquid crystal material is injected by the vacuum injection method into the gap between the substrates of a cell member of each liquid crystal display device, and the injection hole
3
a
is encapsulated by an encapsulating resin, whereby a liquid crystal display device is completed. The vacuum injection method is a method of immersing an injection hole of a liquid crystal display device in a liquid crystal pool which contains liquid crystal after producing a vacuum state in a vacuum
Gray Linda
Sharp Kabushiki Kaisha
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