Metal fusion bonding – Means to apply vibratory solid-state bonding energy to work
Reexamination Certificate
2002-06-28
2004-04-13
Edmondson, L. (Department: 1725)
Metal fusion bonding
Means to apply vibratory solid-state bonding energy to work
C228S110100, C228S004500, C228S180500, C156S073100, C156S580100, C156S580200, C310S323180, C310S325000
Reexamination Certificate
active
06719183
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transducer which is used in a bonding apparatus and to a bonding apparatus which is structured to include the transducer.
2. Prior Art
In a bonding apparatus including wire bonding apparatuses, a transducer such as an ultrasonic horn and the like is used. Bonding is accomplished by applying a load and ultrasonic vibrations to the bonding section of the horn by causing the transducer to vibrate in the lengthwise direction (axial direction) of the transducer by a vibrator and at the same time by lowering a bonding tool mounted at the tip end of the transducer toward the object of process (bonding) and applying a load thereto.
A conventional supporting structure for such a transducer used in a wire bonding apparatus (not shown) is shown in FIG.
6
.
In this transducer, a capillary
66
used as a bonding tool. The capillary
66
is attached to the tip end of an ultrasonic horn
51
that is used as a transducer, and a wire (not shown) passes through the capillary
66
. An ultrasonic vibrator
90
is fastened to the base end of the ultrasonic horn
51
. A flange
54
which has a cylindrical shape and is connected to the ultrasonic horn
51
at the front end of said flange
54
is disposed on the ultrasonic horn
51
. The flange
54
is provided so that it is at a node (i.e., a point where the strain reaches the maximum) position of the ultrasonic vibration, which is applied as a compressional wave (longitudinal wave) in the axial direction, i.e., the direction of length of the horn
51
. The flange
54
is connected to a cylindrical horn support
55
. The horn support
55
is fastened to a transducer holder
56
, and this transducer holder
56
is fastened to a supporting shaft
57
. The supporting shaft
57
is supported on a bonding head (not shown) of the bonding apparatus either directly or via a lifter arm, so that the supporting shaft
57
is free to rotate.
Wire bonding apparatuses of this type are disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) Nos. 5-347334, 6-196532 and 10-303240.
In the above prior art, the flange
54
is disposed at a node position of the ultrasonic vibration in the ultrasonic horn
51
. Accordingly, the energy loss (so-called leakage) via this flange
54
is small; and thus, a defective crushed shape of the ball, stripping of the ball or damage to the substrate, etc., caused by the continued application of unnecessary ultrasonic energy following the completion of bonding can be prevented.
However, as the operation of the bonding apparatus is performed at higher speeds, oscillation during the raising and lowering movement of the transducer becomes a problem. In this respect, since the ultrasonic horn
51
in the above prior art is supported at only one place, it is difficult to effectively suppress the oscillation of the transducer caused by the operation of the bonding head. When such oscillation occurs, an excessive force is applied to the ball during bonding, and defects in the crushed shape of the ball occur. This problem is especially conspicuous in the diameters of press-bonded balls that have been reduced as a result of the increasingly finer pitch of recent semiconductor devices.
In order to deal with oscillation of the transducer during the raising and lowering movement of the transducer, the applicant of the present invention has proposed in Japanese Patent Application Laid-Open (Kokai) No. 2001-24025 a transducer structure as shown in FIG.
7
.
In this structure, an ultrasonic horn
101
used as a transducer is attached to a transducer holder
106
via two horn supporting members
105
that are separate elements from the ultrasonic horn
101
. The attachment positions of the horn supporting members
105
in the axial direction of the ultrasonic horn
101
are adjustable. In this structure, since there are two supporting points, oscillation during the raising and lowering movement of the ultrasonic horn
101
can be effectively prevented. Furthermore, a loss of the ultrasonic vibration (compressional wave) in the axial direction of the horn can also be prevented by causing the attachment positions of the horn supporting members
105
with respect to the ultrasonic horn
101
to coincide with node positions of the vibration of the ultrasonic horn
101
.
Incidentally, as the regions where the horn supporting members (horn supporting members
105
in the structure of
FIG. 7
) are connected to the ultrasonic horn become larger (thicker) in the direction of length of the ultrasonic horn, the portions of these regions that are away from the nodes of the vibration increase. As a result, there is a corresponding increase in the energy loss. More specifically, in order to reduce the energy loss that occurs via the horn supporting members, it is desirable to form the horn supporting members as thin as possible in the axial direction of the ultrasonic horn. However, if the horn supporting members are thin, then there is a corresponding drop in the strength of the horn supporting members.
Furthermore, in the structure in which the ultrasonic horn
51
is supported at a single point as shown in
FIG. 6
, the cutting work for forming the cylindrical flange
54
into a cylindrical shape that is open at one end is difficult, and it is also difficult to reduce the size of the ultrasonic horn
51
. Moreover, in the structure that uses two horn supporting members
105
that are independent elements from the ultrasonic horn
101
as shown in
FIG. 7
, the total number of parts increases, and assembly becomes bothersome.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a transducer having a structure that provides the supporting members of the transducer with strength and that makes it possible to form such supporting members as thin as possible in the axial direction of the transducer.
The above object is accomplished by a unique structure for a transducer which is caused to vibrate by an operation of a vibrator, and the transducer of the present invention comprises: holding portions which are provided in at least two areas that include nodes (or node positions) of vibration in a transducer main body, and connecting portions that connect the holding portions to each other at areas that differ from areas where the holding portions protrude from the transducer main body; and further the transducer main body, the holding portions and the connecting portions are integrally formed from a single material member.
In the structure of the above-described transducer of the present invention, the holding portions are disposed in at least two areas that include nodes of vibration in the transducer main body. Accordingly, oscillation of the transducer is prevented without causing a vibrational energy loss in the axial direction of the transducer. Furthermore, in the transducer of the present invention, the connecting portions that connect the holding portions to each other are provided at areas that differ from areas where the holding portions protrude from the transducer main body. Accordingly, the external force applied to one of the holding portions is dispersed in each of the respective holding portions connected by the connecting portions, and deformation of the holding portions is prevented. Accordingly, the respective holding portions can be formed extremely thin in the axial direction of the transducer main body.
Furthermore, since the transducer main body, holding portions and connecting portions are formed integrally from the same member, a sufficient strength is secured at the connection areas between the holding portions and the transducer main body, and the holding portions can be made even thinner.
In the transducer of the present invention, the holding portions have a plate-form, and they are disposed in a direction of operation of the transducer main body.
Since the plate-form holding portions are disposed in the direction of operation of the transducer main body, the cross-section of the connection areas bet
Kyomasu Ryuichi
Seino Yoshihiko
Edmondson L.
Kabushiki Kaisha Shinkawa
Koda & Androlia
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