Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-07-30
2001-04-03
Sikes, William L . (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S158000, C349S191000
Reexamination Certificate
active
06211935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Industrial Field of the Invention
The present invention relates to an IC mounting structure to mount an IC chip on an opaque circuit substrate such as a circuit substrate made of epoxy resin and, more specifically, relates to the IC mounting structure which is suitable for positioning, i.e., for alignment of an electrode of the IC chip and a terminal to be arranged on the circuit substrate corresponding thereto with each other. The present invention also relates to a liquid crystal device comprising the IC mounting structure. The present invention further relates to an electronic device comprising the liquid crystal device.
2. Description of the Related Art
Liquid crystal devices have been extensively used in recent years for a visual image display part of portable electronic terminals, electronic notebooks, and other electronic devices. The liquid crystal device is generally formed by attaching a pair of transparent substrates, which are respectively provided with a transparent electrode, to each other with a clearance gap provided therebetween, and filling the liquid crystal in the clearance. A polarizer is further mounted on an outer surface of the transparent substrate as necessary, and a color filter is provided on an inner surface of one transparent substrate as necessary. The light to be supplied to the liquid crystal can be modulated by controlling the orientation of the liquid crystal molecules depending on whether the prescribed voltage is applied or no voltage is applied to the transparent electrodes which are opposite to each other with the liquid crystal provided therebetween. Thereby, the visible information such as characters and numerals is displayed.
Concerning a regular liquid crystal device, in order to control the voltage to be applied to the transparent electrodes opposite to each other at a prescribed amount, the electrode terminal formed on the transparent substrate and the electrode of the IC chip for driving the liquid crystal, e.g., a bump electrode, are positionally adjusted, in other words, aligned, and then, conductive-connected to each other, and thereafter, the prescribed voltage is applied to the transparent electrodes in accordance with the instruction from the IC chip. Various kinds of methods to connect the IC chip for driving the liquid crystal to the transparent substrate have been conventionally known. For example, as seen in the liquid crystal device of the so-called COG (Chip On Glass) system, there is an IC mounting structure, where the IC chip is directly mounted on the transparent substrate comprising the liquid crystal panel is known.
According to the IC mounting structure, the IC chip can be observed through the substrate using a camera because the substrate on which the IC chip is mounted is transparent. Accordingly, the alignment of the substrate and IC chip is performed by a simple work. When the IC chip is directly mounted on the transparent substrate, the circuit constitution accompanied by the IC chip is required to be formed on the transparent substrate by ITO (Indium Tin Oxide), etc. In such case, however, no complicated circuit constitution can be formed on the transparent substrate.
On the other hand, when the circuit substrate is formed using an opaque material such as glass epoxy resin, a complicated circuit can be formed. For example, a circuit can be formed on both faces of the circuit substrate and connected to each other using a through hole. When the IC chip is mounted on such an opaque circuit substrate, for example as indicated in
FIG. 8
, an IC chip
53
for driving the liquid crystal is adhered to an opaque circuit substrate
51
using an adhesive such as ACF (Anisotropic Conductive Film)
52
. Further, when the formed circuit substrate unit is mounted on the liquid crystal panel of the liquid crystal device, a bottom side of the opaque circuit substrate
51
is adhered to the transparent substrate of the liquid crystal panel.
As indicated in
FIG. 8
, when the IC chip
53
is mounted on the opaque circuit substrate
51
, an alignment mark
54
K is formed at the prescribed position of the circuit substrate
51
in the conventional practice, while an alignment mark
54
I is formed at the prescribed position of an active side
53
a
of the IC chip
53
, and the IC chip
53
is adhered to the circuit substrate
51
in a condition where both alignment marks
54
K and
54
I are adjusted to each other to be at the same position.
An electrode, for example, a bump electrode
55
is formed on the active side
53
a
of the IC chip
53
. An electrode terminal
65
is formed on a surface of the circuit substrate
51
. Wiring is formed depending on the situation between bump electrodes
55
and between electrode terminals
65
, which is not shown in the figure. The alignment marks
54
K and
54
I are used for positioning the electrodes
55
and the electrode terminals
65
, i.e., for alignment with each other.
To positionally align both alignment marks
54
K and
54
I with each other, the following process is performed in the conventional practice. That is, a prism
56
to guide the light to the camera or the camera itself (not shown in the figure) is inserted between the circuit substrate c
1
and the IC chip
53
, the alignment mark
54
I on the IC chip and the alignment mark
54
K on the circuit substrate are successively photographed using the prism
56
or the like, the prism
56
is pulled out from between the circuit substrate
51
and the IC chip
53
, the position of the circuit substrate
51
and the IC chip
53
is adjusted based on the photographed image by the camera, and then, the circuit substrate
51
and the IC chip
53
are adhered to each other.
However, in the conventional IC mounting structure, the prism
56
or the camera itself (not shown in the figure) must be inserted or pulled out between the circuit substrate
51
and the IC chip
53
to align the circuit substrate
51
with the IC chip
53
, and the photographing view of the inserted prism
56
or the camera must be changed by turning between the circuit substrate
51
and the IC chip
53
, and as a result, it takes a very long time to align the circuit substrate
51
with the IC chip
53
, presenting a problem in that the productivity is worsened.
The present invention is performed in light of the above-mentioned problem in the conventional IC mounting structure, and the object of the present invention is to perform the work to mount the IC chip on the opaque circuit substrate with an extremely simple and quick process.
SUMMARY OF THE INVENTION
In order to achieve the above-mentioned object, the IC mounting structure of the present invention is characterized in that, in the IC mounting structure to mount the IC chip on the opaque circuit substrate, the substrate side alignment mark to be formed on the above-mentioned circuit substrate and the IC side alignment mark which is formed on the IC chip and adjusted to be at the same position as the above-mentioned substrate side alignment mark are provided, and the above-mentioned substrate side alignment mark is a light-transmitting one.
In the IC mounting structure, since the alignment mark on the opaque circuit substrate side is formed of the light-transmitting mark, the IC chip can be photographed by the camera through the alignment mark on the circuit substrate in a condition that the camera is set at the opposite side to the IC chip with the circuit substrate provided therebetween. Namely, both the circuit substrate side alignment mark and the IC side alignment mark can be photographed at the same time by one photographing operation by the camera, and both alignment marks can be aligned based on the photographed information. As a result, the work to mount the IC chip on the opaque circuit substrate can be performed with an extremely simple and quick process.
In the above-mentioned constitution, the “opaque circuit substrate” can be formed of, for example, glass epoxy resin which is a composite material of glass fiber and epoxy resin, ceramics, polyimide film, metal
Chowdhury Tarifur R.
Harness & Dickey & Pierce P.L.C.
Seiko Epson Corporation
Sikes William L .
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