Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-11-30
2004-08-24
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C257S668000
Reexamination Certificate
active
06781662
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a compression-bond-connection substrate to be connected to other members by pressure-bonding. The invention also relates to a liquid crystal device comprised of the compression-bond-connection substrate. Also, the invention relates to an electronic equipment comprised of the liquid crystal device.
BACKGROUND ART
Currently, liquid crystal devices are being widely used in various types of electronic devices, such as portable telephones and portable information terminals. In most of these devices, liquid crystal devices are used to display visual information including characters, numbers, and graphical patterns.
The liquid crystal devices are generally comprised of substrates opposing each other and a liquid crystal sealed between the substrates. In the liquid crystal devices, there is a case in which a compression-bond-connection substrate is connected to either one or both of the substrates. The compression-bond-connection substrate has a drive circuit for driving the liquid crystal device. In the drive circuit, elements including IC chips and passive-element chip parts are mounted, and wiring patterns required to connect the abovementioned elements are formed. Also, substrate-side terminals are formed to conductively connect to terminals on the side of the liquid crystal device at appropriate locations on the compression-bond-connection substrate.
Compression-bonding processing conductively connects substrate-side terminals formed on the compression-bond-connection substrate to terminals formed on the substrates of the liquid crystal device (that is, opposing-side terminals). The compression-bonding processing uses an anisotropic conductive adhesive, such as an ACF (anisotropic conductive film), an ACP (anisotropic conductive paste), or an ACA (anisotropic conductive adhesive). The processing is performed in such a manner that the anisotropic conductive adhesive is sandwiched between the substrate of the liquid crystal device and the compression-bond-connection substrate, and the adhesive is then heated and pressed by using a compression-bonding tool.
As compression-bond-connection substrates, a single-sided wired type, a double-sided wired type, and a multilayer wired type can be considered. The single-sided wired type is a wiring type in which all elements, such as the drive circuit, wiring patterns, and substrate-side terminals are formed on a single side of the substrate. The double-sided wired type is a wiring type in which elements such as the drive circuit, wiring patterns, and substrate-side terminals are separated so as to be arranged on both sides of the substrate, and they become conductive through conductive throughholes as required. The multilayer wired type is a wiring type in which a wiring layer is repeatedly layered with an insulating layer therebetween, and individual layers become conductive through conductive throughholes as required.
FIG. 8
shows a state in which an ACF
51
is used to connect a compression-bond-connection substrate
53
of the double-sided wired type to a compression-bonding target object
52
by compression-bonding. In the state shown, a compression-bonding tool
55
heats the ACF
51
arranged between the compression-bonding target object
52
and the compression-bond-connection substrate
53
at a predetermined temperature and concurrently presses it with a pressure F. The ACF
51
is then caused to harden, resulting in compression-bonding of the compression-bonding target object
52
and the compression-bond-connection substrate
53
. By compression-bonding, a plurality of lands
54
formed on the compression-bond-connection substrate
53
are individually conductively connected to bumps
56
of the compression-bonding target object
52
via conductive balls
59
in the ACF
51
.
In the case of the aforementioned conventional compression-bond-connection substrate
53
of the double-sided wired type, however, while the lands
54
as substrate-side terminals are formed on the compression-bonding side surface, backside wiring patterns
58
are formed on the reverse side of the compression-bonding-side surface. Therefore, the plurality of lands
54
includes both types of lands
54
a
overlapping with the backside wiring patterns
58
and lands
54
b
not overlapping with the backside wiring patterns
58
.
In the case of the compression-bond-connection substrate
53
as described above, when compression-bonding is carried out by using the compression-bonding tool
55
, a high pressure is exerted on the lands
54
a
overlapping with the backside wiring patterns
58
whereas an insufficient pressure is exerted on the lands
54
b
not overlapping with the backside wiring patterns
58
. This causes the connection between the plurality of bumps
56
and the plurality of lands
54
to be partially insufficient, significantly reducing the reliability of the connection therebetween.
A connection assembly as shown in
FIG. 8
uses the compression-bond-connection substrate
53
of the double-sided wired type having a configuration in which the wiring layers are formed on both the front side and the backside of the substrate. Nevertheless, a problem similar to the above arises even in a compression-bond-connection substrate of the multilayer wired type having a configuration in which multiple wiring layers are overlaid.
The present invention is to provide a compression-bond-connection substrate such as that of a double-sided wired type or multilayer wired type that has a configuration in which multiple wiring layers are overlaid, which allows stable provision of a highly reliable compression-bonding connected assembly.
DISCLOSURE OF INVENTION
The present invention provides a compression-bond-connection substrate to be connected by compression-bonding to a compression-bonding target object having opposing-side terminals, comprising a compression-bonding-side surface to be connected to the compression-bonding target object, substrate-side terminals formed on the compression-bonding side surface to be conductively connected to the opposing-side terminals, and backside wiring patterns formed on the reverse face of the compression-bonding-side surface, characterized in that step compensation patterns having substantially the same thickness as that of the backside wiring patterns are formed on the reverse face in positions corresponding to the backsides of the substrate-side terminals.
In the present invention as described above, as shown in
FIG. 5
for example, when a compression-bond-connection substrate
3
is compression-bonded with a compression-bonding target object
2
, an adhesive material
1
such as an ACF is sandwiched therebetween; and furthermore, the adhesive material
1
is heated, and concurrently, both the compression-bonding target object
2
and the compression-bond-connection substrate
3
are pressed together with a pressure F. At this time, substrate-side terminals
4
formed on a compression-bonding-side surface of the compression-bond-connection substrate
3
are conductively connected to opposing-side terminals
6
formed on the compression-bonding target object
2
.
According to the present invention, step compensation patterns
7
having the same thickness as that of backside wiring patterns
8
are formed in positions at the backsides of the substrate-side terminals
4
where the backside wiring patterns do not exist on a reverse face of the compression-bonding side surface of the compression-bond-connection substrate
3
. Therefore, the pressure is applied uniformly by a compression-bonding tool
5
to the individual substrate-side terminals
4
. As a result, all the individual substrate-side terminals
4
can be ensured to be conductively connected to,all the individual opposing-side terminals
6
. That is, according to the compression-bond-connection substrate of the present invention, even in the case of a substrate on which a plurality of wiring patterns overlap with each other, as in a double-sided wired type or a multilayer wired type, a highly reliable compression-bond
Duong Tai
Harness & Dickey & Pierce P.L.C.
Parker Kenneth
Seiko Epson Corporation
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