Metal fusion bonding – Process – With condition responsive – program – or timing control
Reexamination Certificate
1999-01-25
2001-09-11
Elve, M. Alexandra (Department: 1725)
Metal fusion bonding
Process
With condition responsive, program, or timing control
C228S103000, C228S110100, C228S001100, C228S008000
Reexamination Certificate
active
06286749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention, in wire bonder performing an assembling process of semiconductor package, relates to an apparatus for moving a bonding head of a wire bonder in X, Y and Z axial directions and a method for controlling position of the bonding head in order to perform a wire bonding on an objective bonding position.
2. Description of Related Art
Generally, in a wire bonder, there is an apparatus for moving a bonding head, which performs a wire bonding to connect a lead with a pad, to an objective bonding position by moving a X, Y and Z tables.
Hereinafter, an apparatus for moving a bonding head of wire bonder of a prior art will be schematically described, referring to
FIGS. 1 and 1A
.
FIG. 1
is a perspective view showing apparatus for moving a bonding head of wire bonder, in X and Y axial directions, of a prior art.
As shown in
FIG. 1
, the apparatus for moving a bonding head of the prior art comprises a stage
100
having a tenon
100
a
longitudinally (i.e., in the X axial direction) formed on bottom portion and a pair of supporting members
102
protruded from both sides of an end thereof, a X table
104
having a linear motor (not shown) for providing a force moving longitudinally the stage
100
inside thereof and a tenon
104
a
longitudinally formed on bottom portion, an X base
106
having a groove
106
a
for receiving the tenon
104
a
of the X table
104
and guiding the X table
104
to be longitudinally moved, a Y table
108
having a linear motor (not shown) for providing a force moving transversely (i.e., in the Y axial direction) the stage
100
inside thereof, a groove
108
a
for guiding the stage
100
and a tenon
108
b
transversely formed on bottom portion, a Y base
110
having a groove
110
a
for receiving the tenon
108
b
of the Y table
108
and guiding the Y table
108
to be transversely moved, a moving bar
112
jointed to the supporting members
102
in order to move transversely the stage
100
, a bearing
114
arranged on both sides of the moving bar
112
, and a bracket
116
for fixing the bearing
114
.
Further, each of the grooves has a plurality of holes (not shown) for providing air pressure inside thereof so that the tenons
100
a
,
104
a
and
108
b
of stage
100
, X table
104
and Y table
108
can be moved in longitudinal or transversal direction in state that they are apart from the grooves.
When sub-driving portion supplies a control signal to the linear motors in order to control position, direction and angle of the bonding head, each of the linear motors moves rapidly the X and Y tables in a short motion section.
Hereinafter, operation of the apparatus as mentioned above will be schematically described.
In the state that the bonding head is disposed on the stage
100
, when the linear motors disposed inside of X and Y tables
104
and
108
are operated, the X table
104
is moved along the groove
106
a
. Therefore, the stage
100
is longitudinally moved along the groove
108
a
. Also, the Y table
108
is tranversely moved along the groove
110
a
formed on the Y base
110
transversely. At this time, since the tenon
100
a
is received on the groove
108
a
, the stage
100
is transversely moved along with the Y table
108
and the moving bar
112
is transversely moved in the state contacted to the bearing
114
.
In the apparatus, since the moving bar is moved in the state contacted to the bearing, it is difficult to increase velocity of the stage
100
to be moved. In addition, since the bearing is worn by a friction between it and the stage, there is a problem that maintenance of the bearing is required often.
FIG. 1A
illustrates a motion character of the X and Y tables by operation of the linear motors.
As shown in
FIG. 1A
, since a converter changing a rotary force to linear force by means of a cam is used for transferring a mechanical power of motor to the stage, the mechanical power is applied to position offset from the centroid of ths stage “Cm (Xm, Ym, Zm)”. Therefore, since unnecessary moments such as pitching moment “Mx” rolling moment “My” and yawing moment “Mz” causes in the stage, the life of stage is reduced and the entire volumne of apparatus is increased.
In the prior art, an apparatus for moving the bonding head in the Z axial direction moves finely a capillary, which is moved to a bonding position by motion of the stage, in the vertical direction in order to perform the wire bonding by operation of the bonding head.
The apparatus for moving the bonding head in the Z axial direction comprises a rotary servo motor providing a control signal to the linear motors in order to control position, direction and angle of the bonding head, an eccentric-driven cam and a moving block, which has a bearing, for converting a rotary motion into a vertical motion, and an encoder for sensing a rotation angle of the moving block. In this case, the capillary is finely moved by signal outputted from the encoder and performs the wire bonding.
Hereinafter, the apparatus of the prior art will be schematically described how the apparatus operates.
When the X and Y tables are moved by operation of the linear motors and the bonding head is moved to a bonding position, the rotary servo motor is rotated by required value, and the moving block is moved by the eccentric-drived cam in the vertical direction. Therefore, the capillary performs a wire bonding to connect lead to pad.
In the apparatus of the prior art as mentioned above, each of the linear motors have a cylindrical coil or a flat type magnet mainly. When the linear motor consists of the former cylindrical coil, it is difficult that the bonding head is rapidly moved because the apparatus is large and heavy than the other apparatus having a similar features. Also, when the linear motor has the latter flat type magnet, since hysterisis causes in a section which a small power is offerred, the apparatus needs additional device for retaining uniformly the power. Further, during moving, there is a problem that the X and Y tables may be shocked mechanically.
Furthermore, when a rotary servo motor is used as a power source of the apparatus, a device for converting motion, for example such as ball screw, coupling and so on, is required, and disassemble and assemble are difficult because the elements are many. More particularly, since all the positions of the bonding head in the X, Y and Z axes should be converted by means of the rotary servo motor, it is difficult that a final position of the stage is sensed accurately.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an apparatus for moving a bonding head of a wire bonder in X, Y and Z axial directions and a method for controlling position of the bonding head capable of operating finely and controlling rapidly and accurately the bonding head, without additional converter, by disposing directly a linear motor for providing a linear motion character.
Further, the apparatus according to the present invention can accurately sense a final position of stage by separating encoder device and linear motors for moving the stage.
Also, the apparatus according to the present invention can prevent unnecessary moments from causing and reduce entire volumn of the apparatus.
In order to accomplish the above objects, the apparatus for moving a bonding head of wire bonder in the X, Y and Z axial directions, according to the present invention, comprises: a linear guide member for guiding the bonding head in the X and Y axial directions; a XY moving means for providing a moving force in the horizontal (X and Y axial) directions to the linear guide member by causing an induced electromotive force; a Z moving means for providing a moving force in the vertical (Z axial) direction to a block of the bonding head by causing an induced electromotive force; a hinge means for converting the moving force of the Z moving means into a rotating force, and functioning as a rotation center so that the block is rotated in opposite direction to a wire clamp motion.
Lee Dong Hern
Lee Tae Hee
Elve M. Alexandra
Hyundai Electronics Industries Co,. Ltd.
Jacobson & Holman PLLC
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