Metal fusion bonding – Process – Applying or distributing fused filler
Reexamination Certificate
2000-10-19
2002-11-05
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Applying or distributing fused filler
C228S004500, C228S180500
Reexamination Certificate
active
06474538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bonding apparatus and a bonding method performed with the bonding apparatus. The bonding apparatus involves apparatuses such as a bump bonding apparatus for forming projecting electrodes on semiconductor integrated circuits (referred to as ICs hereinafter) in fabricating flip chip type ICs, and a wire bonding apparatus for connecting the ICs with substrate electrodes via a gold wire, or the like.
2. Description of the Related Art
A stud bump bonding technique has been known, which is a technique for joining gold bumps to electrode formed points on flip chip ICs with ultrasound supplied by adopting a wire bonding technique of the ICs. The stud bump bonding technique will be described below.
A generally used conventional bump bonding apparatus is shown in
FIG. 12
, for example. In this bump bonding apparatus, a gold wire
1
is held by a clamper
2
and passed through a capillary
3
. The capillary
3
is provided at a leading end part of an ultrasonic horn
4
, which is disposed on a supporting frame
5
that is swingable via a horizontal axial center
5
a.
The supporting frame
5
is moved in a direction of an arrow
21
by ahead up-down driving device
6
, whereby the capillary
3
is moved up and down via the ultrasonic horn
4
. A voice coil motor is used as the head up-down driving device
6
. The ultrasonic horn
4
has an ultrasonic oscillator
7
.
The supporting frame
5
is provided on a moving table
8
that is movable in X-Y directions which are orthogonal to each other in a horizontal direction. Thus, the capillary
3
is moved in the horizontal direction through movement of the moving table
8
.
9
is a detecting sensor for detecting a positional change in an up-down direction of the supporting frame
5
. A position in an up-down direction of the capillary
3
is obtained on a basis of output information from the detecting sensor
9
.
Above the clamper
2
is arranged an air tensioner
10
for drawing the gold wire
1
upwardly. On the other hand, a heat stage
12
is disposed under the capillary
3
for holding and heating an IC
11
. A spark generating device
14
set in a vicinity of a leading end of the gold wire
1
, which is inserted into the capillary
3
, generates a spark between the device
14
and the leading end of the gold wire, thereby melting the gold wire
1
and forming a gold ball
16
. A camera device
15
for recognizing a position of the IC
11
is installed above the heat stage
12
.
The conventional bump bonding apparatus in the above constitution operates in a manner as described below.
First, a spark is applied from the spark generating device
14
to the leading end of the gold wire
1
that extends downwardly from the capillary
3
, whereby the gold ball
16
is formed. The IC
11
on the heat stage
12
is recognized by the camera device
15
and then, based on information obtained the recognizing operation, the gold ball
16
is positioned by driving the moving table
8
.
Next, the capillary
3
is moved downwardly by the head up-down driving device
6
. Then, when the gold ball
16
comes into contact with an electrode formation point of the IC
11
from above the electrode formation point, an up-down shift of the supporting frame
5
detected by the detecting sensor
9
remains at a constant value, whereby a position of the electrode formation point of the IC
11
is detected. A predetermined force is impressed to the capillary
3
to press the gold ball
16
downwardly. Further, ultrasonic wave oscillation is applied via the ultrasonic horn
4
from the ultrasonic oscillator
7
to join the gold ball
16
to the electrode formation point of the IC
11
. A bump is thus formed at the electrode formation point of the IC
11
. Thereafter, the capillary
3
is moved upwardly a fixed distance by the head up-down driving device
6
and, the gold wire
1
is pulled up by the head up-down driving device
6
with the wire
1
being held by the damper
2
. As a result, the gold wire
1
on the bump is cut at a recrystallization boundary zone in the gold wire produced by the spark, thereby forming a projecting bump
17
on the electrode formation point of the IC
11
.
However, a pitch of electrodes on the IC becomes narrower and consequently a diameter at a base of the bump becomes 65 &mgr;m or smaller. That is,the size of the bump is getting smaller. Thus, the following problems arise. Specifically, when the gold ball
16
comes into contact with the electrode formation point of the IC
11
from above of the electrode formation point, a total inertia of the damper
2
, capillary
3
, ultrasonic horn
4
, ultrasonic oscillator
7
, supporting frame
5
, head up-down driving device
6
, and shift detecting sensor
9
is applied as an impact force to the gold ball
16
. Thus, as the bump becomes smaller in size, the impact force is large enough to crush the gold ball
16
. Thereafter, by applying the ultrasonic wave oscilation to the bump, a problem in that a predetermined height of the bump cannot be obtained results.
On the other hand, in order to restrict the above impact force, if the speed of the capillary
3
is lowered when the gold ball
16
comes into contact with the electrode formation point of the IC
11
, a problem in that production cycle time is disadvantageously lengthy results. Even in the case of normal bumps having a diameter of 65-90 &mgr;m, the same problem results if the speed of the capillary
3
is increased, so as to shorten the production cycle time when the gold ball
16
comes into contact with the electrode formation point of the IC
11
.
SUMMARY OF THE INVENTION
The present invention is accomplished in order to eliminate the above-described problems. An object of the present invention is therefore to provide a bonding apparatus which can shorten a bump formation time and form bumps stably, and also to provide a bonding method performed with the bonding apparatus.
In order to achieve the aforementioned objective, a bonding apparatus is provided according to a first aspect of the present invention, which comprises:
a reduced inertial moving and pressing device having a wire guide member for guiding a wire having a melt ball at a leading end thereof, and a driving part, for moving the wire guide member together with the melt ball from a location that corresponds to the position of melt ball immediately before the melt ball touches an electrode of a semiconductor integrated circuit, and for pressing and joining the melt ball to the electrode; and
a higher speed moving device for moving a move frame having the reduced inertial moving and pressing device;
wherein the reduced inertial moving and pressing device is moved together with the higher speed moving device at a higher speed to the location that corresponds to the position of the melt ball immediately before the melt ball touches the electrode, and is then moved from this location to the electrode at a speed lower than the higher speed, with an inertia caused by the higher speed movement of the reduced inertial moving and pressing device being reduced.
The reduced inertial moving and pressing device can further include an ultrasonic oscillation device set to the wire guide member for ultrasonically oscillating the melt ball via the wire guide member when the melt ball is pressed to the electrode.
The reduced inertial moving and pressing device may be set to the move frame so as to move relatively to the move frame for reducing the inertia of the reduced inertial moving and pressing device.
In an arrangement, the reduced inertial moving and pressing device may have the wire guide member disposed at one end part of the reduced inertial moving and pressing device, and the driving part disposed at another end part thereof. The reduced inertial moving and pressing device is set to the move frame with the wire guide member and the driving part being rocked via an oscillating shaft that is set to the move frame.
The ultrasonic oscillation device may be arranged separately from the mo
Hashimoto Masahiko
Kiyomura Hiroyuki
Sasaoka Tatsuo
Tokunaga Tetsuya
Yamamoto Akihiro
Dunn Tom
Matsushita Electric - Industrial Co., Ltd.
Pittman Zidia
Wenderoth , Lind & Ponack, L.L.P.
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