Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With semiconductor element forming part
Reexamination Certificate
2001-01-19
2002-08-13
Ho, Hoai V. (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With semiconductor element forming part
C257S679000
Reexamination Certificate
active
06433414
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-016491, filed Jan. 26, 2000; No. 2000-016492, filed Jan. 26, 2000; and No. 2000-372946, filed Dec. 7, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a flexible wiring board, a method of manufacturing a flexible wiring board, and a display device such as a liquid crystal panel for a liquid crystal display module connected to a flexible wiring board.
FIGS. 12
to
14
collectively show an example of a conventional liquid crystal display module. As shown in the figures, the conventional liquid crystal display module comprises a liquid crystal display panel
1
and a flexible wiring board
11
. The liquid crystal panel
1
is prepared by bonding a segment substrate
2
and a common substrate
3
to each other with a substantially frame-like seal member
5
interposed therebetween and by sealing a liquid crystal
7
between these substrates
2
and
3
positioned inside the seal member
5
. Segment electrodes
2
a
and a common electrode
3
a
are mounted to those surfaces of the substrates
2
and
3
, respectively, which are positioned to face each other so as to permit a predetermined voltage to be applied to the liquid crystal
7
. The lower side portion in
FIG. 12
of the segment substrate
2
protrudes from the lower side of the common substrate
3
to form a protruding portion
2
b
. A plurality of connection terminals
4
including segment terminals connected to the segment electrodes
2
a
and common terminals connected to the common electrode
3
a
via the seal member
5
are arranged in parallel on one surface of the protruding portion
2
b.
The flexible wiring board
11
comprises an oblong film substrate
12
on which electronic parts are mounted by a TAB (tape automated bonding) system. The film substrate
12
, which is about 75 &mgr;m to 150 &mgr;m thick, is formed of, for example, a polyimide film. A semiconductor chip
13
for driving the liquid crystal display panel
1
such as an LSI and chip parts
14
required for driving the liquid crystal display panel
1
and each comprising a capacitor, a resistor, etc. are mounted on predetermined positions in substantially the central portion of the film substrate
12
. In this case, the semiconductor chip
13
is mounted on a region the film substrate
12
, in which a device hole
15
is formed.
A large number of output wirings
16
are connected to the semiconductor chip
13
on the upper surface of the film substrate
12
in an upper region in
FIG. 12
of the mounting region of the semiconductor chip
13
, and a large number of input wirings
17
extending in parallel are connected to the semiconductor chip
13
and the chip parts
14
in the lower portion in
FIG. 12
of the mounting region of the semiconductor chip
13
. The lower end portion in
FIG. 12
of each input wiring
17
constitutes a first connection terminal
17
a
, with that portion of each input wiring
17
which protrudes into the device hole
15
constituting a second connection terminal
17
b.
The output wiring
16
will now be described. It should be noted that two slits
18
and
19
extending in parallel in a lateral direction are formed in the film substrate
12
in predetermined two positions in an upper portion in
FIG. 12
of the mounting region of the semiconductor chip
13
. The roles played by these two slits
18
,
19
will be described herein later. The output wirings
16
comprise a plurality of first connection terminals
16
a
formed in parallel in an upper end portion of the film substrate
12
, a plurality of second connection terminals
16
b
protruding into the device hole
15
in a portion of the device hole
15
, first drawing wire sections
16
c
formed in parallel in the portions of these slits
18
,
19
and between these slits
18
and
19
, and second drawing wire sections
16
d
arranged between the first drawing wire sections
16
c
and the second connection terminals
16
b
such that the pitch of these second drawing wire sections
16
d
is gradually increased from the second connection terminals
16
b
toward the first drawing wire sections
16
c
. A protective film
10
made of a solder resist is formed on the upper surface of the film substrate
12
including the wirings
16
and
17
except the mounting region of the semiconductor chip
13
, the mounting region of the chip parts
14
, the upper end portion in
FIG. 12
including the first connection terminals
16
a
and the lower end portion including the second connection terminals
17
a
. The protective film
10
is provided with slits
10
a
and
10
b
in positions corresponding to the slits
18
and
19
, respectively, of the film substrate
12
.
The bonding portions comprising the portions of the first connection terminals
16
a
of the flexible substrate
11
are bonded to the bonding portions comprising the connection terminals
4
of the liquid crystal display panel
1
with an anisotropic conductive adhesive (not shown) interposed therebetween.
The reason for forming the device hole
15
in the film substrate
12
will now be described. First the mounting state of the semiconductor
13
will be described. A plating layer (not shown) made of a metal having a low melting point such as tin or a solder is formed on the surfaces of the output wirings
16
and the input wirings
17
. As shown in
FIG. 13
, the upper surfaces of a plurality of bump electrodes
6
made of gold and formed in a peripheral portion on one surface of the semiconductor chip
13
are bonded to the upper surfaces of the second connection terminals
16
b
,
17
b
by a eutectic alloy of gold-tin or gold-solder so as to bond the semiconductor chip
13
to the portion surrounding the device hole
15
of the film substrate
12
.
When the bump electrodes
6
of the semiconductor chip
13
are bonded to the connection terminals
16
b
,
17
b
by a eutectic alloy, the semiconductor chip
13
is disposed on a stage (not shown), and then the film substrate
12
is moved to a region above the semiconductor chip
13
so as to align the positions of the connection terminals
16
b
,
17
b
of the film substrate
12
with the positions of the bump electrodes
6
of the semiconductor chip
13
. Further, a bonding tool is brought into direct contact with the connection terminals
16
b
,
17
b
for the pressurizing under heat. For the operation described above, the device hole
15
is formed in the film substrate
12
. The reason for forming the device hole
15
is as follows. Since the film substrate
12
is relatively thick, i.e., the thickness is about 75 &mgr;m to 150 &mgr;m, the film substrate
12
is unfavorably melted before the bump electrodes
6
and the connecting terminals
16
b
,
17
b
are heated to reach the bonding temperature, when the film substrate
12
is pressurized directly from above by the bonding tool at 530 to 550° C. without forming the device hole
15
. As a result, a defective bonding is generated by the deviation in the position of the wiring.
An example of mounting the liquid crystal display module shown in
FIG. 12
to a circuit board will now be described with reference to FIG.
14
. The liquid crystal display panel
1
is disposed in a predetermined position on the upper surface of a circuit board
21
with the segment substrate
2
being positioned on the lower side. The flexible wiring board
11
is bent at substantially 90° in each of the portions of the slit
18
(
10
a
) and
19
(
10
b
). The portion between the slits
18
and
19
of the flexible wiring board
11
is inserted into a slit
22
formed in a predetermined position of the circuit board
21
, and the portion below the circuit board
21
is allowed to extend along the lower surface of the circuit board
21
. Under this state, the bonding portions comprising the second connection terminals
17
a
of the flexible wiring board
11
are bonded to bonding portions compri
Casio Computer Co. Ltd.
Frishauf Holtz Goodman & Chick P.C.
Nguyen Thinh
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