Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-08-29
2003-08-12
Martin, David (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S801000
Reexamination Certificate
active
06606249
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a connection structure for a display module and a printed substrate for connecting the display module, in which a display panel is connected with a semiconductor device formed by bonding and mounting a semiconductor chip on a flexible wiring substrate, to the printed substrate; the semiconductor device and the display module used in the connection structure; and an electronic component formed by connecting the display module with the printed substrate by means of the connection structure. More specifically, the connection structure of the present invention is appropriate for use in electronic devices requiring high-density wiring, such as a cellular phone or a pager unit.
BACKGROUND OF THE INVENTION
Conventionally, in electronic devices such as a cellular phone and a pager unit, a so-called COF (Chip On Film) type semiconductor device, in which a semiconductor chip is bonded and mounted on a flexible wiring substrate, is widely used. On the other hand, a so-called TCP type (Tape Carrier Package), semiconductor device called, in which semiconductor chips are continuously connected on a flexible wiring substrate, is also used in many applications.
The difference between the COF and the TCP lies in a bonded section between an electrode on the semiconductor chip and an electrode on the flexible wiring substrate.
In the TCP, penetrating holes for mounting semiconductor chips are provided beforehand on a tape carrier material, which is a base substance of a flexible wiring substrate. Then, to each of the penetrating holes, a tip portion of a wiring pattern, called an inner lead, is projected like a cantilever, and the inner lead and an electrode of the semiconductor chip are joined.
On the other hand, in the COF, a penetrating hole is not provided on a tape carrier material in a section bonded with a semiconductor chip. That is, in the COF, a wiring pattern in the section bonded with an electrode of the semiconductor chip is backed with the tape carrier material.
When equipped with a liquid crystal driver IC as a semiconductor chip, the COF or the TCP constitutes a liquid crystal driver which drives a liquid crystal panel. Then, the liquid crystal driver and the liquid crystal panel constitute a liquid crystal module, which is provided as a display section in electronic devices such as a cellular phone.
FIG. 10
shows a case in which a COF is used as a liquid crystal driver for driving a liquid crystal panel which constitutes a display section of a cellular phone. In
FIG. 10
, a COF
32
, which constitutes a liquid crystal driver when a semiconductor chip
31
is provided as a liquid crystal driver IC, is connected with a liquid crystal panel
33
so as to form a liquid crystal module
34
. The liquid crystal module
34
is attached to a printed substrate
35
which forms an electronic circuit. Here, the COF
32
of the liquid crystal module
34
and the printed substrate
35
are electrically connected via a connector
36
.
Conventionally, when connecting a COF (or TCP) of such a liquid crystal module and a printed substrate, a connecting method via a connecter, as mentioned above, and a connecting method using solder are widely used.
Meanwhile, when manufacturing an electronic device using such a liquid crystal module, especially that manufactured in large quantity such as a cellular phone, the following requirements should be satisfied in a process for attaching a liquid crystal module to a printed substrate (a connection process).
(1) Since a product test is conducted after attaching a liquid crystal module to a printed substrate, it should be designed that the liquid crystal module can be easily detached from the printed substrate.
(2) The connection of the liquid crystal module and the printed substrate can be easily automated, without recourse to manual connection.
(3) High reliability should be ensured in the connection of the liquid crystal module and the printed substrate.
However, in the foregoing method using solder to connect a COF of a liquid crystal module with a printed substrate, it is difficult to detach the COF from the printed substrate once they are connected. Therefore, the above requirement (1) cannot be satisfied.
Besides, in the method for connecting the COF of the liquid crystal module with a printed substrate using a connector, as shown in
FIG. 10
, a terminal section formed at one end of the COF
32
is inserted into the connector
36
for connection. However, since a flexible wiring substrate
32
a
, which is a base substance of the COF
32
, is a soft film, it is difficult to automate the connection and thus manual connection is required. Therefore, the above requirement (2) cannot be satisfied.
Further, when using the connector
36
, an actuator is required for pressing the terminal section of the COF
32
, resulting in an increase in the number of components required. Besides, due to the adoption of the actuator, the total height of the connection structure on the printed substrate
35
is increased, which is disadvantageous for thin mounting structure.
To solve such problems, Japanese Unexamined Patent Publication No. 9-22760/1997 (Tokukaihei 9-22760, published on Jan. 21, 1997) discloses a method for connecting a liquid crystal module and a printed substrate which allows easy detachment and easy connection process automation. According to the publication, a snap-on method using pawls is adopted.
In this method, as shown in
FIG. 11
, engaged holes
44
are provided on a COF
42
of a liquid crystal module
41
, near a connection pad
43
for establishing electrical connection with a printed substrate
45
. On the printed substrate
45
, in a section for fixing the liquid crystal module
41
is mounted a holding base
46
, which is provided with a contact
47
corresponding to the connection pad
43
and holding members (pawls)
48
corresponding to the engaged holes
44
. By snapping the COF
42
of the liquid crystal module
41
on the printed substrate
45
, the corresponding engaged holes
44
and the holding members
48
are engaged so as to fix the COF
42
on the printed substrate
45
.
At the same time, the connection pad
43
on the COF
42
and the contact
47
on the printed substrate
45
come into contact, and the connection pad
43
and the contact
47
are electrically connected.
In such a structure, by pressing the COF
42
onto the printed substrate
45
from one direction, the holding members
48
are snapped into the engaged holes
44
. At the same time, the connection pad
43
on the COF
42
and the contact
47
on the printed substrate
45
are electrically connected. Therefore, the connecting process can be easily automated.
Meanwhile, such a snap-on method requires design ideas ensuring that the connection pad
43
on the COF
42
and the contact
47
on the printed substrate
45
are connected at the same time when the COF
42
is snapped on the printed substrate
45
.
Because, for example, if the contact
47
on the printed substrate
45
is formed in a plane shape, in the same way as the connection pad
43
on the COF
42
, the connection pad
43
and the contact
47
are difficult to make contact with each other just by snapping the COF
42
on the printed substrate
45
, failing to obtain highly reliable connection. Especially, when the COF
42
is provided with components, the components might obstruct the contact between the connection pad
43
and the contact
47
.
In response, in the foregoing publication, the contact
47
provided on the printed substrate
45
is formed as a conductive protruding electrode in a folded shape, and it is structured that the COF
42
is snapped on the printed substrate
45
, pressing the contact
47
from above with the plane connection pad
43
on the COF
42
.
However, the structure of the foregoing publication has problems as follows.
1) Space for placing the holding base
46
integrated with the holding members
48
and the contact
47
is required on the printed substrate
45
, limiting the mounting area allocated for other
Chikawa Yasunori
Satou Kunihiro
Tomokuni Hiroaki
Phan Thanh S.
Sharp Kabushiki Kaisha
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