Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Including integrally formed optical element
Reexamination Certificate
2002-03-01
2004-05-18
Phan, James (Department: 2872)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Including integrally formed optical element
C438S157000, C349S046000, C349S047000, C349S153000
Reexamination Certificate
active
06737289
ABSTRACT:
This application claims the benefit of the Korean Application No. P2001-10775 filed on Mar. 2, 2001, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display, and more particularly, to a liquid crystal display panel and a method for fabricating the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for improving adhesion between substrates.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) has two sheets of glass substrates and a liquid crystal layer sealed between the glass substrates, and a thin film transistor (TFT) is used as a switching device for switching a signal voltage to the liquid crystal layer.
Referring to
FIG. 1
, an LCD is a non-emission device provided with a lower glass substrate
1
having a TFT as a switching device formed thereon, an upper glass substrate
2
having a color filter formed thereon, and a liquid crystal
3
injected between the glass substrates
1
and
2
, thereby obtaining an image by electro-optical characteristics of the liquid crystal
3
. Since the LCD consumes a low power consumption and is portable, it draws a great attention as a next generation display which can replace a cathode ray tube (CRT).
More specifically, the lower glass substrate
1
has a TFT array
4
, a pixel electrode
4
a
, and an orientation film
8
formed thereon, while the upper glass substrate
2
has a light shielding layer
5
, a color filter layer
6
, a common electrode
7
, and the orientation film
8
. The lower substrate
1
and the upper substrate
2
are bonded by a sealant
9
, such as an epoxy resin. A driving circuit
11
on a PCB
10
is connected to the lower glass substrate
1
through a tape carrier package (TCP)
12
for generating and forwarding various control signals and signal voltages required for displaying an image on the LCD panel.
The sealant
9
is used for bonding and fixing the two sheets of glass substrates. In addition, it prevents external moisture from penetrating into the liquid crystal because the liquid crystal easily absorbs water. As a result, resistivity of the liquid crystal is lowered, and impurities may be formed therein when the liquid crystal is exposed to the air.
There are an inorganic sealant and an organic sealant. Although the inorganic sealant is used in the early generation LCD, the inorganic sealant is not used any longer as a liquid crystal material is developed. Among the organic sealants, there are epoxy group resins, phenol group resins, and acryl group resins, which may be sorted into two liquid types in which a main agent and a hardening agent are to be mixed in use, and one liquid type containing the main agent and the hardening agent as a single solution.
Depending on methods of hardening in the sealant, there are a thermo-hardening type, and a UV hardening type. Both types are required a strong adhesion, a high crystallinity, a good printability, and the like. Further, for accurately controlling a cell gap, a uniform spreading is necessary when the substrate is under pressing, heating, and curing processes.
The thermo-hardening resin, such as epoxy or phenol, has advantages of a high mechanical strength, a strong adhesion, and a good cross-linking. On the other hand, the UV hardening resin may be a better type in applying a larger sized device because it has a low hardening temperature, and a short hardening time period. Therefore, a thermal expansion problem may be avoided and bonding between the substrates is improved in applying to a large sized substrate.
A related art LCD panel will be explained with reference to the attached drawings.
FIG. 2
illustrates a plane view of a related art LCD panel, wherein a first substrate
21
and a second substrate
21
a
are arranged to face into each other, and a liquid crystal layer (not shown) is formed between the first and second substrates
21
and
21
a
. Each of the first and second substrates
21
and
21
a
has an active region ‘A’ and a pad region ‘P’ defined thereon. The first substrate
21
has a plurality of thin film transistors and pixel electrodes on the active region ‘A’ and a plurality of gate pads
23
and data pads
25
on the pad region ‘P’. There is a UV hardening sealant
27
in the pad region ‘P’ on the outside of the active region ‘A’, more specifically, on a pad link part PL, for bonding the first and second substrates
21
and
21
a.
FIG. 3
illustrates a detailed view of an ‘X’ part of
FIG. 2
, wherein there are a plurality of gate lines G
1
, G
2
, . . . , Gn and data lines D
1
, D
2
, . . . , Dn formed in the active region ‘A’ on the first substrate
21
. The gate lines and the data lines cross one another, thereby defining a plurality of pixel regions each having a pixel electrode
31
. There are a TFT (not shown) arranged at each crossing part of the gate lines G
1
, G
2
, . . . , Gn and the data lines D
1
, D
2
, . . . , Dn.
There are gate pads GP
1
, GP
2
, . . . , GPn and data pads DP
1
, DP
2
, . . . , DPn, connected to a driving IC, for linking driving signals and data signals applied to the gate pads GP
1
, GP
2
, . . . , GPn and the data pads DP
1
, DP
2
, . . . , DPn to the gate lines G
1
, G
2
, . . . , Gn and data lines D
1
, D
2
, . . . , Dn at the active region ‘A’ through gate pad links PL_g, and data pad link PL_d, respectively.
Actually, the gate pads GP
1
, GP
2
, . . . , GPn and the data pads DP
1
, DP
2
, . . . , DPn are electrically connected to the TCP and anisotropic conductive film (ACF) by a transparent conductive film
33
, for receiving the driving signals and the data signals from the external driving IC. The gate pads and the data pads are connected to the TCP and the ACF via the transparent conductive film
33
having a good electrical conductivity and good adhesion because the gate pads and the data pads formed of non-transparent metal have poor adhesion to the TCP and the ACF.
The aforementioned related art LCD panel will be explained in more detail.
FIG. 4
illustrates a cross-sectional view along line IV—IV, showing the gate pads of the LCD panel.
Referring to
FIG. 4
, there are the gate line G
1
, the gate pad GP
1
, and the gate pad link PL_g formed on the first substrate
21
having the active region ‘A’ and the pad region ‘P’ defined thereon. The pad region ‘P’ has a region for the gate pad GP
1
and a region for the gate pad link PL_g. A gate insulating film
41
is formed on the entire surface of the first substrate
21
including the gate pad GP
1
. There are a protection film
43
on the gate insulating film
41
and a transparent conductive film
33
passed through the gate insulating film
41
and the protection film
43
, and electrically connected to the gate pad GP
1
.
The gate line G
1
, the gate pad link PL_g, and the gate pad GP
1
are formed as a unit, formed of a non-transparent metal, such as aluminum (Al), chromium (Cr), molybdenum (Mo), copper (Cu), an aluminum alloy, a bilayer of the foregoing metals, or the like.
On the second substrate
21
a
at the active region ‘A’, there are a light shielding layer
45
extended to a region for the gate pad link PL_g, a color filter layer
47
for displaying colors, and a common electrode
49
and the pixel electrodes
31
(shown in
FIG. 3
) for applying a voltage to the liquid crystal LC. The photo-hardening sealant
27
along the outside of the active region ‘A’ having the gate pad link PL_g formed thereon, for bonding the first substrate
21
and the second substrate
21
a.
In the meantime, there are thin film transistors and pixel electrodes (both not shown) on the first substrate
21
at the active region. That is, at a portion where the gate line and the data line are crossed, there are a thin film transistor having a gate electrode, a gate insulating film
41
on the gate electrode, a semiconductor layer and an ohmic contact layer on the gate insulating film
41
, and a source and a drain electrodes, and a pixel electrode
31
connected to the drain electrode
Shin Woo Sup
Woo Joung Won
LG. Philips LCD Co. Ltd.
Morgan & Lewis & Bockius, LLP
Phan James
LandOfFree
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