Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1999-07-28
2002-04-02
Gaffin, Jeffrey (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S255000, C174S260000, C361S760000, C361S773000, C361S779000, C257S737000, C257S778000, C257S783000
Reexamination Certificate
active
06365840
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10-219216 filed Aug. 3, 1998 and Japanese Application No. P11-037471 filed Feb. 16, 1999, which applications are incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrical connecting device and an electrical connecting method for electrically connecting an electrical connecting portion of a first object to an electrical connecting portion of a second object.
2. Description of the Related Art
With recent smaller sized and decreased thickness of electronic parts, circuits for use therein have been denser and more precise, so that connection of such an electronic part to a fine electrode is difficult with conventional soldering method, rubber connector or the like. Therefore, adhesive agent and film material (hereinafter referred to as connecting member) having anisotropy excellent in fine pitching and conductivity have been often used.
This connecting member is constituted of the adhesive agent containing a predetermined amount of conductive material such as conductive particles and so on. This connecting member is disposed between each of protruding electrodes of an electronic part and a conductive pattern of a printed wiring board. By applying a pressure or heating with a pressure, the electrodes on both the parts are electrically connected to each other and electrodes formed adjacent each other of the same are provided with an electrical insulation. As a result, the protruding electrodes of the electronic part and the conductive pattern of the printed wiring board are bonded to each other and fixed.
A basic concept for making the above connecting member correspond to the fine pitch is that an insulation between adjacent electrodes is secured by making a diameter of each of conductive particles smaller than the insulating portion between the adjacent electrodes, the containing amount of the conductive particles is set to such an extent that the particles do not contact each other and conductivity of the connecting portion is obtained by making the conductive particles exist securely on the electrodes.
If the diameter of the conductive particle is reduced according to the above conventional method, however, an area of the conductive particle' surface increases remarkably so that a secondary cohesion occurs, thereby combining adjacent particles with each other. As a result, the insulation between the adjacent electrodes cannot be maintained. If the containing amount of the conductive particles decreases, the number of the conductive particles on electrodes to be connected also decreases so that the number of contacting points becomes short. As a result, the conduction between the connecting electrodes cannot be obtained. Consequently, it is difficult to make the connecting member correspond to fine pitch while a long term connecting reliability is maintained.
That is, by a remarkable correspondence to the fine pitch trend, miniaturization of an electrode area and a gap (space) between adjacent electrodes have progressed, so that the conductive particles on the electrodes flows out between the adjacent electrodes with adhesive agent because of pressurization at the time of connection or heating with a pressure.
To solve such a problem, conventionally, a connecting member in which by coating the conductive particles for insulation, a quantity of the conductive particles in the connecting member is increased and a connecting member constituted of an adhesive layer containing the conductive particles and a layer not containing them have been proposed.
FIGS. 1 and 2
show these conventional connecting members.
In case where an object is a glass substrate
200
as shown in
FIG. 1
, flatness of a mounting region for an IC (integrated circuit)
201
in glass substrate
200
is about ±0.5 &mgr;m and if in protruding electrodes
202
of the IC
201
, there is few deflection (about ±0.5 &mgr;m) in the height of each protruding electrode like a gold plated bump, it is possible to electrically connect the wiring pattern
203
of the glass substrate
200
to the protruding electrodes
202
of the IC
201
through conductive particles
205
contained in a connecting member
204
.
Because each of the parts such as the ICs is flat, if the thickness of the connecting member
204
is a height of the protruding electrode
202
of the IC
201
(ordinarily, about 15-25 &mgr;m and ITO pattern wired on a glass is some Angstrom) about ±5 &mgr;m, the connecting member
204
is charged securely under the IC
201
. Therefore, the connecting member
204
does not have to be made thicker than necessary and at the stage of temporary pressure-fitting (pressurization) of an initial period of mounting, the conductive particles
205
can be nipped between the wiring pattern
203
on the glass substrate
200
and the protruding electrodes
202
of the IC
201
. After that, even if the binder of the connecting member flows out at the time of pressure-fitting (heating with a pressure), the nipped conductive particles
205
do not flow out, so that when the connecting member is hardened, an electrical connection is established between the wiring pattern
203
on the glass substrate
200
and the protruding electrode
202
of the IC
201
through the conductive particles
205
.
In FIG.
1
(A), the connecting member
204
(for example, anisotropic conductive film: ACF) is bonded to the glass substrate
200
. Usually, the anisotropic conductive film is bonded onto the glass substrate
200
by carrying out ordinary heating with a pressure (heating with a pressure is performed at a pressure of about 100 N/cm
2
and a heating temperature of 70-100° C.). With this state, positioning between the wiring pattern
203
of the glass substrate
200
and the protruding electrode
202
of the IC
201
is carried out.
In FIG.
1
(B), the IC
201
is temporarily press-fit to the glass substrate
200
. The temporary press-fitting of the IC
201
is carried out by only a pressure or heating with a pressure (heating temperature is about 70-100° C.).
In FIG.
1
(C), the IC
201
is finally press-fit to the glass substrate
200
. The final press-fitting of the IC
201
is carried out by heating with a pressure. Because a temperature at this time is higher than the glass transition temperature of the anisotropic conductive film, a flow of the binder occurs. At this time, the conductive particles
205
nipped between the protruding electrode
202
of the IC
201
and the wiring pattern
203
of the glass substrate
200
does not flow, but the other conductive particles
205
flow.
FIG.
1
(D) shows a state in which the anisotropic conductive film is hardened. If heating with a pressure is carried out in the final press-fitting, after resin flows, it is hardened. This series of the above described processes is the connecting process.
However, if the object is not a glass substrate but a printed wiring board
300
as shown in
FIG. 2
, a deflection (± several &mgr;m) may be generated in the height of the wiring pattern
303
or a deflection (± several &mgr;m) may be generated in the height of the protruding electrode
202
of the IC
201
like a gold wire bump. In this case, if the thickness of the connecting member
204
is height of the wiring pattern
303
of the printed wiring board
300
(about 20 &mgr;m) plus height of the protruding electrode of the IC (about 20 &mgr;m), it is necessary to add 10-20 &mgr;m to the above thickness by considering the safety.
In this case, because the thickness of the connecting member
204
is large at the stage of temporary press-fitting (pressurization) of the initial period of mounting, the conductive particles
205
cannot be nipped between the wiring pattern
303
of the printed wiring board
300
and the protruding electrode
202
of the IC
201
. After that, when the binder of the connecting member
204
flows at the time of final press-fitting (heating with a
Honda Noriyuki
Suga Yasuhiro
Gaffin Jeffrey
Patel I B
Sonnenschein Nath & Rosenthal
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