Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-12-08
2001-09-04
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S150000, C349S152000, C349S187000
Reexamination Certificate
active
06285433
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for mounting a TCP film to display panels such as a liquid crystal panel, a light-emitting type matrix panel and the like.
BACKGROUND ART
Because of the recent technological advancement in such areas as micro fabrication, liquid crystal material, packaging and the like, liquid crystal panels with a display screen measuring diagonally from 5 cm to 50 cm, which allow television pictures and various video images to be displayed flawlessly in practical use, are made available on a commercial basis.
Also, a liquid crystal panel, which displays images in color, is realized without difficulty by having one of the glass substrates, which constitute the liquid crystal panel provided with a RGB colored layer.
Particularly, with a liquid crystal panel having a switching element built in each respective pixel, the so -called active type liquid crystal panel, the displayed video images have little cross-talk, a quick response and a high contrast ratio.
Each of these liquid crystal panels has usually a matrix composition of 100 to 1000 scanning lines and 200 to 2000 signal lines, respectively, and an effort in development on both a larger screen size and a higher resolution has recently been under way to cope with the requirement for enhanced display capacity.
FIG. 4
is a perspective view of part of an active type liquid crystal panel and an active type liquid crystal panel
1
is formed of an active substrate
2
and an opposing substrate
9
with liquid crystal filled therebetween.
The active substrate
2
comprises:
a translucent insulating substrate;
a plurality of scanning lines disposed on one of the main surfaces of the translucent insulating substrate;
a plurality of signal lines intersecting generally at a right angle with the scanning lines;
at least one or more of insulating layer sandwiched between the scanning lines and the signal lines;
at least a switching element and a pixel disposed at each respective point of intersection of the scanning line and signal line; and
a cluster of terminal electrodes of the scanning lines and signal lines disposed outside the image display area of the active substrate
2
.
The opposing substrate
9
is formed of a glass substrate constituting a translucent insulating substrate having translucent and conductive opposing electrodes.
The active substrate
2
and opposing substrate
9
are separated from each other with a predetermined gap of about several micrometers maintained therebetween by means of such a spacer material as a resin fiber, resin bead and the like, and the space (gap) between the foregoing two substrates is sealed at the peripheral edges of the opposing substrate
9
by the use of a sealant and an encapsulating material, both formed of an organic resin, thereby creating a totally enclosed space, into which liquid crystal is filled.
Color displaying is performed by a color displaying function, which is served by an organic thin film of about 1 to 2 micrometers thick formed as a colored layer containing one selected from a dye and a pigment, or both, disposed on the surface of the opposing substrate
9
on the totally enclosed side. In this case, the glass substrate
9
is also referred to as a color filter.
Depending on the nature of a liquid crystal material, a polarizer is affixed on the upper surface of the opposing substrate
9
or the lower surface of the glass substrate
2
, or on both thereof, thereby allowing the liquid crystal panel
1
to act as an electoptic element.
A majority of the liquid crystal panels now in use are a TN (twistnematic) type and each respective panel requires usually two polarizers.
With the liquid crystal panel structured as described in above, a semiconductor integrated circuit chip
3
, for example, supplying a driving signal is directly connected to a terminal electrode cluster
6
of the scanning lines according to a COG (Chip-On-Glass) packaging method and a TCP film
4
is connected to a signal electrode cluster
5
of the signal lines and fixed thereon by pressing down a conductive adhesive applied to the connecting points according to a TCP (Tape-Carrier-Package) packaging method outside the image display area of the active substrate
2
.
The TCP film
4
is formed of a polyimide resin of around 0.1 mm thick as the base, for example, with terminals made of a copper foil that is gold plated or solder plated. (The terminals are not shown in the drawing.)
For the sake of convenience, the two kinds of packaging method are illustrated on the drawing at the same time but one of the methods is selected as appropriate in practice.
The image display area of the liquid crystal panel
1
is connected with the terminal electrode cluster
5
of the signal lines and the terminal electrode cluster
6
of the scanning lines via wiring channels
7
and
8
, respectively. However, the wiring channels
7
and
8
are not necessarily formed of the same conductive material as the terminal electrode clusters
5
and
6
.
With the aforementioned liquid crystal panel, a liquid crystal cell comprises a translucent and conductive pixel electrode formed on the active substrate
2
, a likewise translucent and conductive opposing electrode formed on the opposing substrate
9
and liquid crystal filled between the two glass substrates.
With an IPS type liquid crystal panel that has been recently put into market with the capability of expanding viewing angles, the translucent electrode (opposing electrode) is no longer required to be disposed on the color filter since the liquid crystal cell comprises a pair of comb like electrodes formed on one (active substrate) of the glass substrates and liquid crystal filled between the two glass substrates. However, a detailed description is not given here to this type liquid crystal panel.
In order to display video images on a liquid crystal panel, electrical signals are fed to terminal electrodes of both scanning lines and signal lines formed according to the aforementioned TCP or COG packaging methods. For a reduction in costs and/or enhancement in reliability involved with packaging by minimizing the number of connecting points, there have been increasing tendencies recently to make heavy use of the COG packaging method.
Although there are a variety of methods and means, by which packaging is performed according to TCP or COG, a typical packaging method that is most frequently employed is described here with reference to FIG.
5
.
A plurality of terminal electrodes
5
(6) are disposed on the surface of the active substrate
2
and an insulating layer
15
including a gate insulating layer and a passivation insulating layer is disposed between the adjoining terminal electrodes
5
(6). The insulating layer
15
on each respective terminal electrode is eliminated selectively, thereby making almost all the surface area of each respective terminal electrode
5
(6) free of the insulating layer
15
.
Next, after having the active substrate
2
and the color filter (not shown in
FIG. 5
) put together by adhesion into a panel form in a cell fabrication process, the active substrate
2
and the TCP film
4
with conductive patterns
12
(bump electrodes), each of which is plated with such a conductive material
11
as gold, solder and the like, are connected with each other by an application of pressure and heat via a thermosetting anisotropic conductive film (ACF)
14
containing conductive fine particles
13
in a packaging process.
The conductive patterns
12
(bump electrodes) formed of a copper foil and the base film of the TCP film
4
are joined together fixedly with an adhesive
16
.
The conductive fine particle
13
serves as a conductive medium to have the conductive patterns
12
(bump electrodes) and the terminal electrodes
5
(6) connected one another electrically and a typical conductive fine particle
13
is formed of a plastic ball, the surface of which is plated with gold or nickel.
The anisotropic conductive rubber
14
makes a plurality of the conductive fine particles
13
contained therein coagulate an
Chowdhury Tarifur R.
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P.
Sikes William L.
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