Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Ball or nail head type contact – lead – or bond
Reexamination Certificate
1999-04-06
2001-04-24
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Ball or nail head type contact, lead, or bond
Reexamination Certificate
active
06222281
ABSTRACT:
INDUSTRIAL FIELD OF THE INVENTION
The present invention relates to an integral circuit (IC) chip in which a plurality of bumps forms an input terminal and an output terminal, and to an IC chip assembly including the IC chip. Furthermore, the present invention relates to a liquid crystal device including the IC chip. Furthermore, the present invention relates to an electric apparatus including the IC chip.
DESCRIPTION OF THE RELATED ART
Liquid crystal devices are widely used for visual image display units in a variety of electric apparatuses such as mobile phones and video cameras. Such electric apparatus and liquid crystal devices are equipped with a variety of semiconductor components. The “semiconductor component” is an IC chip itself or an IC chip assembly in which an IC chip and a substrate are integrated.
With respect to the above-mentioned IC chip, a bare chip IC which is not packaged, an IC which is packaged and has a terminal on the rear surface, and the like have been known. In addition, with respect to the above-mentioned IC assembly, the following has been known: A chip-on-board (COB) or a multi-chip-module (MCM) in which one or a plurality of IC chips is mounted on one substrate, a chip-on-flexible-printed-circuit (COF) in which an IC chip is mounted on a flexible-printed-circuit (FPC), or the like.
When the above-mentioned IC chip is conductively connected to an object member to be bonded, such as a wiring substrate, there is a method in which after formation of bumps on an input terminal and an output terminal of the IC chip, a conductive connection is achieved by utilizing the bumps. In this method, an anisotropic conductive adhesive such as an anisotropic conductive film (ACF) is intercalated between the IC chip and the object member to be bonded, and the connection is performed using the anisotropic conductive adhesive. In this state, the bumps of the IC chip are conductively connected to an electrode terminal on the object member to be bonded by conductive particles containing in the anisotropic conductive adhesive.
However, as shown in
FIG. 10
, in a conventional IC chip, out of a plurality of surfaces of bumps
52
which is provided on the active sufrace
51
a
as an input and output terminal, surfaces
52
a
to which is applied an anisotropic conductive adhesive is formed to be plane and approximately parallel to an active surface
51
a
of an IC chip
51
.
Generally, when the IC chip
51
is bonded to an object member to be bonded using the anisotropic conductive adhesive, the IC chip
51
is pressed to the object member to be bonded by intercalating the anisotropic conductive adhesive. The pressed anisotropic conductive adhesive is extruded laterally. When the surfaces
52
a
of the bumps
52
are a plane and are parallel to the active surface
51
a
of the IC chip
51
as described above, the anisotropic conductive adhesive, which is pressed by the surface
52
a
of the bump
52
, spreads so as to escape from the bump
52
. Therefore, conductive particles around the surfaces
52
a
of the bumps
52
decrease, so that satisfactory conductivity is not obtained.
The present invention is performed in view of the above-described problem. An object of the present invention is to prevent conductive particles in an anisotropic conductive adhesive from escaping from surfaces of bumps of an IC chip, and to retain more numerous conductive particles around the surfaces of the bumps.
(1) To this end, an IC chip in accordance with the present invention includes a built-in semiconductor and a plurality of bumps exposed to the exterior, and provided on a surface, the bumps being pressed and bonded to an object member to be bonded using an anisotropic conductive adhesive; wherein a mounting surface of the bump opposed to the object member to be bonded has a larger height in the outward direction of the IC chip than a height in the inward direction thereof.
With respect to the IC chip, the height of the outer portion of the bump is larger than the height of the inner portion thereof. Thus, when an anisotropic conductive adhesive is pressed by the IC chip, conductive particles in the anisotropic conductive adhesive are prevented from outwardly moving toward the outside of the IC chip by the high outer portion of the bump. As a result, numerous conductive particles can remain around the bump so that substantial conductivity can be obtained.
In addition, “an anisotropic conductive adhesive” is a conductive adhesive including conductive particles, and is not limited to a particular adhesive material in practice. An anisotropic conductive film (ACF) which has the overall form of a film, an anisotropic conductive adhesive which has the overall form of a paste and the like are exemplified.
In addition, “an object to be bonded” is an arbitrary member to which an IC chip is mounted. A variety of members such as a hard wiring substrate, a soft wiring substrate, a flexible wiring substrate, and a transmissive substrate for a liquid crystal panel are exemplified.
(2) With respect to the above-described IC chip, a difference (H-h) between the outward height H of the bump and the inward height h thereof is preferably smaller than a diameter of a conductive particle in the anisotropic conductive adhesive. Thus, numerous conductive particles can be trapped around the bump.
(3) With respect to the above—described IC chip, the bump may be formed so as to include a concave portion on a mounting surface opposed to the object member to be bonded. With this form, conductive particles can remain in the concave portion, so that a greater number of conductive particles can be trapped around the bump.
(4) An IC assembly in accordance with the present invention includes an IC chip and a substrate for mounting the IC chip using an anisotropic conductive adhesive; wherein the IC chip is an IC chip according to any one of the paragraphs (1) to (3) above. With this IC assembly, numerous conductive particles can remain around the bump in the same way as described above in paragraphs (1) to (3), which explain the IC chip. Therefore, substantial conductivity can be obtained.
(5) Next, a liquid crystal device in accordance with the present invention includes a liquid crystal panel including a pair of substrates containing a liquid crystal sandwiched therebetween, and an IC for driving the liquid crystal directly or indirectly connected to the liquid crystal panel using an anisotropic conductive adhesive; wherein the IC for driving the liquid crystal is composed of the IC chip according to any one of the paragraphs (1) to (3). With this liquid crystal, numerous conductive particles can be retained around the bump in the same way as described above in paragraphs (1) to (3), which explain the IC chip. Therefore, substantial conductivity can be obtained.
In addition, “a direct connection of the IC for driving the liquid crystal to the liquid crystal panel” means that after mounting the IC for driving the liquid crystal to an intermediate substrate other than the liquid crystal panel, the IC for driving the liquid crystal is connected to the liquid crystal panel by connecting the intermediate substrate to the liquid crystal panel.
(6) Next, an electric apparatus in accordance with the present invention includes an IC chip wherein the IC chip is an IC chip according to any one of paragraphs (1) to (3). With this electric apparatus, numerous conductive particles can be retained around the bump in the same way as described above in paragraphs (1) to (3), which explain the IC chip. Therefore, substantial conductivity can be obtained.
REFERENCES:
patent: 3480412 (1969-11-01), Duffek, Jr. et al.
patent: 5473197 (1995-12-01), Idaka et al.
patent: 5844320 (1998-12-01), Ono et al.
patent: 5889326 (1999-03-01), Tanaka
Clark Sheila V.
Harness & Dickey & Pierce P.L.C.
Seiko Epson Corporation
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