X-ray detector and method of fabricating the same

Details X-ray detector and method of fabricating the same X-ray detector and method of fabricating the same

1999-10-05

2002-11-05

Sherry, Michael (Department: 2829)

Semiconductor device manufacturing: process

Making device or circuit responsive to nonelectrical signal

Responsive to electromagnetic radiation

C438S064000, C257S433000

Reexamination Certificate

active

06475824

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an X-ray detector and methods of fabricating the same, and more particularly to the electrical connection between an X-ray detector panel and an integrated circuit chip of the X-ray detector.
2. Discussion of the Related Art
In an X-ray detector, a package connecting an external integrated circuit chip with the X-ray detector serves not only for electrical connection, but also for transmission of electrical signals, mechanical support and release of heat generated during operation. The importance of the package is increasing recently because the signal transmission speed of a chip is much higher than that of the package and the signal delay time in the package determines the efficiency of an X-ray detector.
The wire bonding method has been employed for packaging an X-ray detector, which is a method wherein a chip and a pad formed in a lead frame are connected by a wire such as Au, Al, etc. The wire bonding method is used, in general, with integrated circuit chips for a wide range of process conditions with good reliability. An example is illustrated in
FIG. 1
, where a gate line
3
or data line
4
of a TFT (thin film transistor)
2
is connected by a wire
6
with an integrated circuit
5
on an X-ray detector panel
1
, and the integrated circuit
5
is also connected with a printed circuit board
7
by a wire
6
.
However, the wire bonding method is a sequential connection method wherein connecting terminals are connected one by one. Therefore, it requires a long time when the number of connecting terminals is large, as in an X-ray detector, and connection is impossible where the distance between connecting terminals is very short. In addition, the connection area is undesirably large owing to the height of the wire loop.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an X-ray detector and a method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for fabricating an X-ray detector, whereby the time period required in the process of connecting an X-ray detector panel and a drive integrated circuit is shortened, and whereby a very short connection between connecting terminals becomes possible and the connection area is reduced.
Another object of the present invention is to provide an X-ray detector fabricated by such a method.
In order to achieve the above objects, the present invention provides in a first aspect, a method for fabricating an X-ray detector comprising a gate pad connected to a gate line disposed crosswise in a first direction, a data pad connected to a data line disposed lengthwise in a second direction substantially perpendicular to the first direction, a switching element disposed in the region where a gate line and a data line cross, a storage capacitor connected with the switching element, scanning and data integrated circuit chips for operating the switching element and a printed circuit board for driving the scanning and data integrated circuit chips, which comprises:
forming at least two protruding electrodes, or bumps, on the scanning integrated circuit chip;
providing a first polyamide film having an electrode adhered thereto, the electrode having an inner lead and an outer lead;
providing a second polyamide film having an electrode adhered thereto, the electrode having an inner lead and an outer lead;
bonding the inner leads of the first and the second polyamide films with the bumps, respectively;
bonding the outer lead of the first polyamide film to the gate pad with an anisotropic conducting film interposed therebetween; and
connecting the outer lead of the second polyamide film to the printed circuit board by soldering.
In a second aspect, the present invention provides a method for fabricating an X-ray detector similar to that as described above, which comprises:
forming at least two bumps on the data integrated circuit chip;
providing a first polyamide film having an electrode adhered thereto, the electrode having an inner lead and an outer lead;
providing a second polyamide film having an electrode adhered thereto, the electrode having an inner lead and an outer lead;
bonding the inner leads of the first and the second polyamide films with the bumps, respectively;
bonding the outer lead of the first polyamide film to the data pad with an anisotropic conducting film interposed therebetween; and
connecting the outer lead of the second polyamide film to the printed circuit board by soldering.
In the above methods according to a first mode (tape carrier package) of the invention, the switching element is preferably a thin film transistor.
The above methods may further comprise encapsulating the integrated circuit chip and the inner leads of the electrodes of the first and second polyamide film with a resin after bonding the inner leads of the first and second lead electrodes with the protruding conductor of the integrated circuit chip. An epoxy resin may be preferably used as the encapsulating resin.
In a third aspect, the present invention provides a method for fabricating an X-ray detector comprising first and second gate pads connected to first and second gate lines, respectively, each disposed crosswise in a first direction, first and second data pads connected to first and second data lines, respectively, each disposed lengthwise in a second direction substantially perpendicular to the first direction, a switching element disposed in a region where one of the gate lines and one of the data lines cross, a storage capacitor connected on a same plane with the switching element, and scanning and data integrated circuit chips for operating the switching element, which comprises:
providing a flexible printed circuit board for operating the scanning integrated circuit chip;
providing an anisotropic conductive film;
forming on the scanning integrated circuit chip first and second protruding conductors;
bonding the first gate pad with the first protruding conductor on the scanning integrated circuit chip;
bonding the second gate pad with the second protruding conductor on the scanning integrated circuit chip; and
bonding the flexible printed circuit board with the second gate pad by the anisotropic conductive film.
In a fourth aspect, the present invention also provides a method for fabricating an X-ray detector as described above, which comprises:
providing a flexible printed circuit board for operating a data integrated circuit chip;
providing an anisotropic conductive film;
forming on the data integrated circuit chip first and second protruding conductors;
bonding the first data pad with the first protruding conductor on the data integrated circuit chip;
bonding the second data pad with the second protruding conductor on the data integrated circuit chip; and
bonding the flexible printed circuit board with the second data pad by the anisotropic conductive film.
In the above methods according to a second mode of the invention (chip-on-glass method), the switching element is preferably a thin film transistor.
In a fifth aspect, the present invention also provides an X-ray detector fabricated according to the first and second modes set forth above.
Additional features and advantages of the invention will be set forth in the description, which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.


REFERENCES:
patent: 5043582 (1991-08-01), Cox et al.
patent: 5648674 (1997-07-01), Weisfield et al.
patent: 59003283 (1984-01-01), None
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