Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-12-18
2002-03-19
Cuneo, Kamand (Department: 2841)
Metal working
Method of mechanical manufacture
Electrical device making
C174S254000, C174S260000, C174S257000, C029S825000, C029S846000
Reexamination Certificate
active
06357111
ABSTRACT:
TECHNICAL FIELD
The present invention relates to conductive connection between elements by using conductive paste. In particular, the present invention relates to an inter-electrode connection structure for effecting conductive connection between substrate side electrodes formed on a substrate and element side electrodes formed on electronic elements mounted on the substrate and to an inter-electrode connection method for realizing the structure. Further, the present invention relates to a semiconductor device formed so as to include an IC chip, and to a semiconductor mounting method for joining such a semiconductor device to an external substrate such as a PCB (printed circuit board). Further, the present invention relates to a liquid crystal device and an electronic apparatus produced by using the semiconductor device and the semiconductor mounting method.
BACKGROUND ART
Nowadays, a liquid crystal device is widely used as the visible image display section of various electronic apparatuses, such as a portable telephone and a video camera. Various kinds of semiconductor devices are arranged in such a liquid crystal device and electronic apparatus. By a semiconductor device it is meant here an IC chip, an IC structure in which an IC chip and a substrate are formed into an integral unit, or the like. Known IC chips include a bare chip IC which has undergone no packaging and an IC which has undergone packaging and which has terminals on its back side. Known examples of such an IC structure include a COB (chip on board), in which a plurality of ICs are mounted on a single substrate, an MCM (multi chip module), and a COF (chip on film) in which an IC is mounted on an FPC (flexible printed circuit).
Conventionally, when connecting a semiconductor device to an external substrate or, further, when joining a liquid crystal driving IC to a light transmitting substrate in a liquid crystal device, mounting methods such as wire bonding and TAB (tape automated bonding) have been used.
Further, when manufacturing the above IC structure, it is necessary to effect conductive connection of electronic elements such as IC chips to a circuit board such as a PCB. Conventionally, to effect such conductive connection, mounting techniques such as wire bonding technique and heat seal technique have been used.
However, in the case of the above conventional mounting methods for semiconductor devices, it is difficult to conduct minute pitch mounting. Thus, it has been difficult to correctly join a semiconductor device or the like having an electrode terminal of a minute pitch of 80 &mgr;m or less, in particular, 50 &mgr;m or less to an external substrate.
Further, in the case of the above-mentioned mounting technique related to the conductive connection between electrode terminals, it is impossible to connect electrode terminals to each other whose inter-electrode pitch is minute. Further, a large area is required for mounting. For example, in the connection method using the wire bonding technique, an inter-electrode-terminal pitch of approximately 130 &mgr;m is the limit, and, in the heat seal technique, an inter-electrode-terminal pitch of approximately 240 &mgr;m is the limit. Thus, it is difficult to connect electrode terminals arranged at a minute pitch of 80 &mgr;m or less, in particular, 50 &mgr;m or less.
In view of this, it is a principal object of the present invention to effect conductive connection of electrode terminals arranged at a minute pitch correctly and with high reliability.
In particular, the present invention has been made in view of the problems in the mounting technique related to the above mentioned conductive connection between electrodes. It is a first object of the present invention to provide an inter-electrode connection structure and an inter-electrode connection method in which conductive connection of electrodes arranged at a minute pitch can be correctly effected and in which the requisite area for the conductive connection can be reduced.
Further, the present invention has been made in view of the problems in the above mounting method for semiconductor devices or the like. It is a second object of the present invention to provide an apparatus and a connection method in which, in relation to the joining of a semiconductor element having minute pitch electrode terminals to a substrate, it is possible to achieve an improvement in the reliability of the joint portion and to achieve an improvement in yield.
DISCLOSURE OF INVENTION
To achieve the above objects, the inter-electrode connection structure, inter-electrode connection method, semiconductor device, semiconductor mounting method, liquid crystal device, and electronic apparatus according to the present invention are constructed as follows:
In the inter-electrode connection structure of the present invention, which is an inter-electrode connection structure for effecting conductive connection between a substrate side electrode formed on a substrate and an element side electrode formed on an electronic element mounted on the substrate, (1) the substrate side electrode and the element side electrode are arranged so as to be in contact with or close to each other, (2) a conductive paste is provided so as to connect the terminals at the contact or proximity portion, and (3) the conductive paste is applied to the contact or proximity portion of the terminals by being sprayed in particles.
In this inter-electrode connection structure, the conductive paste is placed on the terminals by spraying it in particles, so that, even when the electrode pitch is minute, it is possible to correctly place the conductive paste on each of the electrodes, whereby conductive connection between minute pitch electrodes is possible. Further, since the electrodes are connected to each other by using conductive paste, the conductive connection state is stable, thereby achieving an improvement in reliability. Further, since conductive connection is effected with a conductive paste in a particle form, the mounting area may be small.
In the above construction, the “conductive paste” is a paste-like or kneaded-matter-like soft conductive material, and is formed, for example, by dissolving an appropriate conductive material in solvent. Further, as the method for “spraying the conductive paste in particles”, it is possible to adopt a well-known fluid spraying method, which has conventionally been known as an ink jet system or the like. This ink jet system can be realized by, for example, a well-known piezoelectric system, a well-known bubble spraying system or the like. The piezoelectric system is a method according to which a fluid such as ink is sprayed in particles by utilizing a force generated by supplying electricity to a piezoelectric element. The bubble spraying system is a method according to which a fluid is sprayed in particles while generating bubbles by partially heating the fluid by using a heat generating substance. It goes without saying that any other appropriate method can be adopted.
Regarding this inter-terminal connection structure, the following forms are possible.
(1) The light transmitting substrate of a liquid crystal panel can be used as the substrate, and a glass substrate with a built-in liquid crystal driving IC can be used as the electronic element. In this form, even when the glass substrate with a built-in IC is long, conductive connection of the glass substrate to the light transmitting substrate can be correctly effected. Further, since the area for the conductive connection may be small, it is possible for the liquid crystal panel to be made generally very small.
(2) A flexible or non-flexible printed circuit board can be used as the substrate, and a multi-layer IC chip can be used as the electronic element. Here, the “multi-layer IC” is a semiconductor element in which a plurality of IC chips are stacked together. Generally speaking, in this multi-layer IC, wiring is provided on the side surface portion of the multi-layer structure, and the element-side electrode is provided at the forward end of the wiring.
(3) A f
Cuneo Kamand
Harness & Dickey & Pierce P.L.C.
Seiko Epson Corporation
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