Metal fusion bonding – With means to juxtapose and bond plural workpieces – Wire lead bonder
Reexamination Certificate
2000-08-28
2004-10-26
Edmondson, L. (Department: 1725)
Metal fusion bonding
With means to juxtapose and bond plural workpieces
Wire lead bonder
C228S180500
Reexamination Certificate
active
06808102
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a wedge wire bonding apparatus, and in particular to such an apparatus having an improved xy-table orientation.
BACKGROUND OF THE INVENTION
Wire bonding apparatus for the bonding of semiconductor and other electronic components on to an integrated circuit board are generally divided into two types; ball bonding apparatus in which a ball, for example, of gold, is formed at the end of a wire to be bonded, and wedge wire bonding apparatus in which a wire is deformed as it is bonded.
Ball bonding apparatus require the bonding head to be movable in the three axes X, Y and Z. For wedge wire bonding apparatus, however, the workpiece or bonding head must also be orientable about its axis &thgr;. For example, if a wire is being bonded at two places, before the first bond is made, the workpiece is rotated so that the bonding head is aligned with a line joining the first and second bonds then, after the first bond has been made, the bonding head is moved towards the second bonding location. Of course it will be appreciated that it is relative movement of the bondhead and the workpiece that is necessary. One may be fixed and the other may move, or vice versa.
PRIOR ART
FIGS. 1
to
3
show in plan and perspective views three conventional configurations for such wire bonding apparatus. Referring firstly to
FIG. 1
, a workpiece
1
is mounted on rotatable table
2
. Rotatable table
2
is in turn mounted on sliding tables
3
,
4
that are adapted to move in mutually orthogonal X and Y axes. Located above the workpiece
1
is a bonding head
5
including a transducer
6
that extends along an axis. The bonding head
5
is adapted to move vertically along the Z axis by means of a sliding mechanism disposed on the side of a bonding head supporting member
7
. In the prior art configuration of
FIG. 1
it will be noted that the transducer
6
is supported such that it is parallel with the x axis.
In use, before a first bond had been made, the axis of the transducer
6
is aligned along the direction of a line between the first and the second bonds by rotating the workpiece using the rotating table. After the first bond is formed, the workpiece
1
is then moved along the X axis by sliding table
3
until the workpiece
1
is in the correct position for the bonding head
5
to carry out the second bond. The bonding head moving down in the Z direction forms the bond, and the bonding head moves up again in the Z direction after the bond has been formed.
In the prior art bonding apparatus of
FIG. 1
it will be noted that the bonding head supporting member
7
is located in the space defined by the interior angle of the XY axes and that the transducer axis is parallel to the X axis of the moving table
3
. The prior art configuration of
FIG. 2
is similar to
FIG. 1
except that in this configuration the transducer axis is parallel to the Y axis of moving table
4
. In the prior art configuration of
FIG. 2
, after the workpiece has been rotated so that the positions of the first and second bonds have been aligned with the transducer
6
, the workpiece
1
is moved along the Y axis by means of sliding table
4
.
FIG. 3
shows an alternate prior art configuration in which the bonding head supporting member
7
is located outside of the interior angle defined the XY axes and the transducer
6
is orientated such that the transducer axis is perpendicular to a line bisecting the XY axes. In this prior art configuration, after the work piece has been rotated so that the transducer
6
is aligned with the first and second bond locations, the work piece is moved along both the X and Y axes to move the work piece into the correct position for the second bond to be formed.
It should be noted that in the prior conventional arrangements as shown in
FIGS. 1
to
3
, the position of the operator of the bonding apparatus is such that he looks at the bonding apparatus from a position by the side of the X axis and views the bonding operation along a direction perpendicular to the X axis. It is also important to note that in the prior art arrangement of
FIG. 3
an operator views the bonding process at an angle of 45° to the transducer axis which makes it difficult to properly observe the bonding process, and in particular makes it difficult to carry out necessary alignment and set-up steps.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved configurations for wedge wire bonding apparatus that provide more efficient operation.
According to the present invention therefore there is provided wedge wire bonding apparatus comprising:
(a) means for supporting a workpiece,
(b) a bonding head including a transducer having a longitudinal axis,
(c) means for causing relative movement of the workpiece and the transducer along orthogonal X and Y axes simultaneously, and
(d) means for supporting the bonding head above the workpiece such that the longitudinal axis of said transducer lies along a line dividing said X and Y axes.
An advantage of the present invention in its preferred forms is that by moving the transducer relative to the workpiece along both the X and Y axes simultaneously, rather than only one of the two axes, the time spent for the movement of the transducer is significantly reduced. The maximum reduction in the travelling time of either the transducer or the workpiece (depending on which actually moves) is when the line bisects the X and Y axes equally making an angle of 45° to the X and Y axes and the travelling distance is reduced by a factor of 0.707 compared with when the movement is along one axis only. This reduces the Travelling time by nearly 30%. The relative XY motion of the transducer and the workpiece is not of course the only time consuming part of the bonding operation, nonetheless it is a major one (30-50% of the cycle) and the total bonding cycle time can be reduced by around 9 to 15%.
In one embodiment of the invention the workpiece supporting means comprises a rotary table for rotating the workpiece.
In one embodiment, the bonding head is fixed and the workpiece supporting table moves in the X and Y axes. Alternatively, the workpiece supporting table is fixed in the X and Y axes and the bonding head moves in the X and Y axes.
It is also possible to optimise the position of an operator viewing the bonding process. In particular in a preferred embodiment of the invention that apparatus includes a position for an operator to observe the bonding procedure, and wherein the transducer is positioned so as to point in the direction of the operator position. This is an optimum position in that it allows the operator to observe fully the bonding process and greatly facilitates any required alignment and set-up operations that are necessary at the commencement of or during a bonding process.
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Chung Siu Wai
Ho Siu Yan
Ho Wing Cheung
Law Hon Shing
ASM Assembly Automation Ltd.
Burns Doane Swecker & Mathis L.L.P.
Edmondson L.
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