Metal fusion bonding – Process – With condition responsive – program – or timing control
Reexamination Certificate
1998-10-01
2001-03-27
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Process
With condition responsive, program, or timing control
C228S004500, C228S008000, C228S180500
Reexamination Certificate
active
06206266
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wire bonding apparatus with a bonding arm supported so as to move upward and downward by an elastic member and also to a method for controlling the apparatus
2. Prior Art
A wire bonding apparatus in which the bonding arm is supported so as to be movable upward and downward and driven by an elastic member is shown in FIG.
2
.
The bonding arm
4
of this bonding apparatus has a bonding tool
1
at one end thereof and is fastened to one end of a supporting frame
3
. The supporting frame
3
is attached to a moving table
5
via a plate spring
4
which is assembled in the form of a cross, so that the supporting frame
3
is swingable upward and downward as shown by an arrow V, and a moving table
5
is mounted on an XY table
6
. The coil
8
of a linear motor
7
is fastened to another end of the supporting frame
3
, and the magnet
9
of this linear motor
7
is fastened to the moving table
5
. A linear scale
10
is attached to the rear end (right-side end in
FIG. 4
) of the supporting frame
3
.
Examples of a wire bonding apparatus of this type are described in Japanese Patent Application Pre-Examination Publication (Kokai) Nos. S58-184734 and H6-29343 and Japanese Examined Patent Application Publication (Kokoku) No. H6-80697.
With the structure described above, the supporting frame
3
and bonding arm
2
are caused to swing in the direction of arrow V about the cross-shaped plate spring
4
by the linear motor
7
, and the bonding tool
1
is, as a result, moved up and down. Furthermore, the moving table
5
, supporting frame
3
, bonding arm
2
and bonding tool
1
are moved horizontally (or in X and Y directions) by the XY table
6
. By way of the combination of the vertical movement and horizontal movement of the bonding tool
1
as described above, a wire
12
passing through the bonding tool
1
is connected between the first and second bonding points on the workpiece (not shown). In other words, a ball
13
formed at the tip end of the wire
12
is bonded to the first bonding point, and then the other portion of the wire
12
is bonded to the second bonding point. During this bonding of the wire
12
to the first and second bonding points, a load or a bonding load is applied by the linear motor
7
so that the ball
13
and wire
12
is pressed against the bonding points on the workpiece by the bonding tool
1
.
Next, the operation system for the above bonding apparatus and the control configuration of the linear motor
7
will be described.
The operation system substantially comprises an external input-output means
20
and a computer
21
. The external input-output means
20
is used for inputting and outputting various types of information (required for the operation of the apparatus) with respect to the computer
21
. The computer
21
comprises a control circuit
22
, an operating circuit
23
, a reference coordinate register
24
and a height position counter
26
. The control circuit
22
controls the external input-output means
20
, operating circuit
23
, reference coordinate register
24
and height position counter
26
.
In the reference coordinate register
24
, the height position of the bonding arm
2
is stored. More specifically, the value of the height position is inputted into a position control circuit
30
as one position command. When the value is thus inputted, the position control circuit
30
compares a previous position command and a new position command and generates an amount of movement of the bonding tool based upon the difference between the two position commands. This amount of movement is transmitted to a motor driver
31
as a driving signal
33
.
The motor driver
31
generates electric power which is used to move the bonding tool
1
to a designated height position in accordance with the driving signal
33
. Generally, electric power is the product of voltage and current; therefore, actual control of the linear motor
7
can be accomplished by controlling either the voltage or current, or both. Accordingly, the following explanation describes the case where the driving current
35
(and not a driving voltage) that flows through the linear motor
7
is controlled. The circuit described in Japanese Examined Patent Application Publication (Kokoku) No. H6-18222 may be cited as an example of the circuit that controls the driving current. When the driving current
35
generated by the motor driver
31
is applied to the coil
8
of the linear motor
7
, a driving force is generated; and as a result of this driving force, the supporting frame
3
, bonding arm
2
and bonding tool
1
are caused to swing about the plate spring
4
(or moved up and down).
Furthermore, the height position counter
26
of the computer
21
counts signals from an encoder
32
which converts signals from the position sensor
11
into a signal format which can be inputted into the computer
21
and generates an actual height position of the linear scale
10
. The computer
21
is provided beforehand with a ratio of the amount of movement of the bonding tool
1
in the vertical direction to the amount of movement of the linear scale
10
in the vertical direction, and a quantization coefficient of the position sensor
11
, i. e., a coefficient which converts the amount of movement into an electrical signal. Accordingly, the actual height position of the bonding tool
1
is determined by calculating the value indicated by the height position counter
26
via the operating circuit
23
based upon the value described above. The term “height position of the bonding tool” refers to the height position at which the bonding tool I contacts the object to which a load is to be applied.
The bonding arm
2
and bonding tool
1
swing about a fulcrum
4
a
of the cross-shaped plate spring
4
. Accordingly, it is desirable that the bonding tool
1
be in a vertical position; in other words, it is desirable that the bonding arm
2
be in a horizontal position when the bonding tool
1
contacts the bonding point. With the bonding arm
2
thus adjusted to a horizontal position, an instruction to place the bonding arm
2
in a horizontal position is sent to the computer
21
by the external input-output means
20
. As a result of this instruction, the control circuit
22
sends control information for this purpose to the position control circuit
30
via the reference coordinate register
24
; and from the position control circuit
30
, a driving signal
33
which produces the driving current
35
is sent to the motor driver
31
. On the basis of this driving signal
33
, the motor driver
31
produces the driving current
35
of a specified polarity and magnitude and outputs this driving current
35
to the coil
8
.
Instructions concerning the movement of the bonding arm
2
are thus transmitted from the computer
21
in this manner.
In the system wherein the supporting frame
3
is supported by the plate spring
4
so as to swing upward and downward as described above, when no driving current
35
flows through the coil
8
or when no driving force is generated in the linear motor
7
, the bonding arm
2
stops at the equilibrium position B as shown in FIG.
5
. The equilibrium position B is a balanced position where the driving force of the plate spring
4
and the weight balance of the bonding tool
1
, bonding arm
2
, supporting frame
3
, coil
8
and linear scale
10
, etc. are supported by the plate spring
4
.
In other words, the driving force of the plate spring
4
in this case acts in a direction which causes the bonding arm
2
to return to the equilibrium position B. More specifically, when the bonding arm
2
is in a position A which is higher than the equilibrium position B, the plate spring
4
generates a driving force which pushes the bonding arm
2
downward toward the equilibrium position B; and when the bonding arm
2
is in a position C or D which is lower than the equilibrium position B, then the plate spring
4
generates a driving force which pushes the bondi
Hayashi Hijiri
Takahashi Kuniyuki
Kabushiki Kaisha Shinkawa
Koda & Androlia
Ryan Patrick
Stoner Kiley
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