JP2002158254A - Method of controlling wire clamp mechanism in wire bonding apparatus - Google Patents

Abstract

(57) [Problem] To provide a control method of a wire clamping mechanism in a wire bonding apparatus which does not cause a problem even at a high speed operation. SOLUTION: In a control of a wire clamp mechanism for clamping a wire fed to a capillary tool of a wire bonding apparatus, a clamp arm mechanism for sandwiching the wire is opened and closed by a voice coil motor to perform a clamp operation for clamping the wire. By driving the clamp arm mechanism in the closing direction by driving in the closing direction with a drive current value I2 larger than the clamp current value I1 corresponding to the predetermined clamp load, the voice coil motor is then opened by the current value I3 of (-). By driving in the direction, the speed of the closing operation is reduced, and after the deceleration, the wire is clamped with a predetermined clamp load by driving with the clamp current value I1. As a result, it is possible to reduce the impact on the wire at the time of clamping without delaying the tact time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a wire clamp mechanism in a wire bonding apparatus for clamping a wire fed to a capillary tool in the wire bonding apparatus.

[0002]

2. Description of the Related Art Wire bonding is widely used as a method for electrically connecting a semiconductor element to a circuit electrode on a substrate. In this wire bonding, one end of a wire such as a gold wire is bonded to an external connection electrode of a semiconductor element by a capillary tool, and the wire in the bonded state is moved by a capillary tool to form a bond on a circuit electrode of a substrate. Pull to the point and bond. In this bonding operation,
Since the wire is supplied as a continuous wire, one wire
It is necessary to cut each bonding operation. The cutting of the wire is performed by pulling up the capillary tool in a state where the wire is clamped by the cut clamper disposed above the capillary tool, thereby tearing the wire at a position immediately above the bonding point.

[0003]

For this reason, the cut clamper must clamp the wire with a sufficient holding force to tear the wire. However, the clamp mechanism of the cut clamper of the conventional wire bonding apparatus has the following problems as the bonding operation speeds up. The cut clamper causes the clamp arm mechanism to perform opening and closing operations, and clamps the wire between the distal ends of the clamp arms during the closing operation. For this reason, when the speed of the clamping operation is increased, the impact on the wire increases.

If the impact becomes excessive, when the ends of the clamp arms come into contact with each other, they rebound and the clamping operation becomes unstable, causing damage such as crushing or scratching of the wire, and bonding when pulling up the wire. There is a case where the wire cannot be cut normally at the point and a trouble occurs. If the closing operation is gradual to avoid such a problem, an extra operation time is required for each clamping operation, and the tact time is increased. As described above, the conventional bonding apparatus has a problem in that the wire clamp mechanism causes a problem due to an increase in the speed of the bonding operation.

Accordingly, an object of the present invention is to provide a method of controlling a wire clamp mechanism in a wire bonding apparatus which does not cause a problem even at a high speed operation.

[0006]

According to a first aspect of the present invention, there is provided a method for controlling a wire clamping mechanism in a wire bonding apparatus, comprising: a wire bonding apparatus for bonding a wire to a surface to be bonded; A method of controlling a clamp mechanism, wherein the electric open / close drive means corresponds to a predetermined clamp load in a clamp operation for clamping the wire by opening / closing a clamp arm mechanism that sandwiches the wire from both sides by electric open / close drive means. A first closing step of causing the clamp arm mechanism to perform a closing operation by driving in a closing direction with a driving current value larger than the clamping current value to be driven, and driving the electric open / close driving means in the opening direction following the first closing step. Deceleration step of reducing the speed of the closing operation by performing , And a second closing step of sandwiching the wire at a predetermined clamping load electric closing drive means after deceleration process and driving at the clamp current.

According to the present invention, the clamp arm mechanism performs the closing operation by driving the electric opening / closing driving means in the closing direction with a driving current value larger than the clamping current value corresponding to the predetermined clamping load in the clamping operation. After that, the electric opening / closing driving means is driven in the opening direction to reduce the speed of the closing operation, and after this deceleration step, the electric opening / closing driving means is driven by the clamp current value to clamp the wire with a predetermined clamp load, thereby performing the clamping operation. The impact on the wire at the time of clamping can be reduced without causing a delay in the entire tact time.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view of a wire bonding apparatus according to one embodiment of the present invention, FIG. 2A is a plan view of a cut clamper of the wire bonding apparatus according to one embodiment of the present invention, and FIG. FIG. 3 is a graph showing the driving characteristics of the cut clamper of the wire bonding apparatus according to the embodiment of the present invention. FIG. 3 is a graph showing the closing operation of the cut clamper of the wire bonding apparatus according to the embodiment of the present invention.
FIG. 5 is a diagram illustrating the operation of the wire bonding apparatus according to one embodiment of the present invention.

First, the overall structure of the wire bonding apparatus will be described with reference to FIG. On the upper surface of the base 1, a substrate 2
Is placed. A chip (semiconductor element) 3 to be wire-bonded is mounted on the substrate 2. A large number of circuit electrodes 5 serving as wire bonding points are formed around the chip 3.
The wire is bonded to the external connection electrode of the chip 3 and the circuit electrode 5 as the bonding target surface. Thereby, the chip 3 is connected to the circuit electrode 5.

A holding plate 6 is provided on the substrate 2. The holding plate 6 is connected to a rod 7 a of a cylinder 7. When the rod 7 a is pulled in, the substrate 2 is pressed and fixed by the holding plate 6. A movable table 10 is provided on the side of the base 1, and a drive box 11 is provided on the movable table 10. A horn 12 extends forward from the drive box 11, and a capillary tool 13 is held at a tip of the horn 12.

A wire 15 used for wire bonding is inserted through the capillary tool 13. Wire 15
Is supplied in a state wound on a spool 14, and a wire 15 fed from the spool 14 is supplied to the tension applying section 1.
7. Insert the capillary tool 13 through the cut clamper 16. The cut clamper 16 performs opening and closing operations to clamp and fix the wire 15. That is, the cut clamper 16 has a wire clamp mechanism that clamps the wire by sandwiching the wire from both sides. A torch 19 is provided near the lower end of the capillary tool 13. The torch 19 forms a metal ball at the lower end of the wire 15 by generating a spark between the torch 19 and the wire 15 protruding from the lower end of the capillary tool 13.

X direction motor 10X and Y direction motor 10Y
Is driven to move the movable table 10, the drive box 11, the horn 12, the capillary tool 13 and the like on the movable table 10 move horizontally in the X direction and the Y direction. The capillary tool 13 is housed in the drive box 11 and driven up and down by a Z-direction motor (not shown).

Next, the cut clamper 16 will be described with reference to FIG. 2A, the cut clamper 16 has a configuration in which two arms, a first arm 21 and a second arm 22, are extended from a base 20. FIG. The first arm 21 is fixed to the base 20, and the second arm 22 is supported on the base 20 by pins 23. Second
At the rear end 22a of the arm 22, a VCM (voice coil motor) serving as an electric opening / closing driving unit of the cut clamper 16 is provided.
Is fixed, and a stator 24 is fixed to a bracket 20 a at the rear end of the base 20.

The coil 25 is connected to the VCM drive unit 27. By controlling the VCM drive unit 27 by the control unit 28, it is possible to control the power supply to the coil 25 and control the opening / closing operation of the cut clamper 16. it can. The first arm 21 and the second arm 22 are mutually urged by a compression spring 26 on the rear side of the pin 23, and when the coil 25 is not driven and is not driven, the first arm 21
And the tip of the second arm 22 is in a closed state.

FIG. 2B shows the opening / closing drive characteristic of the cut clamper 16 by controlling the drive current of the VCM coil 25, that is, the current value I on the abscissa and the tip of the first arm 21 and the second arm 22 cause a wire. Is shown in relation to a clamp load f for clamping the pressure. Here, when the current value is 0, the closing load f0 due to the urging force of the compression spring 26 is obtained.
Then, the first arm 21 and the second arm 22 are closed. I1, I
2 is the specified clamp load and the maximum clamp load f, respectively.
1, a current value corresponding to f2. F3 is a clamp load (-) when the cut clamper 16 is in the open state, and I3 corresponds to this load.

Next, referring to FIG.
Will be described. FIG. 3A is a graph showing a temporal change of the set current value of the coil 25 when the cut clamper 16 performs the closing operation.
(B) shows a change in the gap G at the distal end of the first arm 21 and the second arm 22 in the closing operation. First, at the timing t0, the current value I3 in the (−) direction corresponding to the open state is supplied to the coil 25, and the cut clamper 16 is in the open state. And timing t1
At, the closing operation is instructed by the control unit. At this time, first, for a predetermined time T1 from timing t1, power is supplied to the coil 25 with the current value I2 corresponding to the clamp load f2 larger than the regular clamp load f1, and the cut clamper 16 performs the closing operation (first closing). Process).

Next, at the timing t2, following the first closing step, power is supplied to the coil 25 again with the current value I3 to reduce the relative operation between the coil 25 and the stator 24 (deceleration step). Then, at the timing t3 when the predetermined deceleration time T2 has elapsed, the cut clamp 16 is caused to perform the closing operation by the current value I1 corresponding to the regular clamp load f1 (second closing step). Here, the times T1 and T2 and the current value I2 are set such that the gap G between the first arm 21 and the second arm 22 becomes substantially zero at the timing t3. Thus, when a high-speed clamping operation is required, a quick clamping operation can be performed without causing instability of the clamping operation due to collision between the arms and damage to the wire due to applying an excessive closing load. be able to.

This wire bonding apparatus has the above configuration, and its operation will be described below with reference to FIGS. 4 (a) to 4 (c) and FIG. 5 (a)
(C) shows a series of operations in the order of operation. FIG.
(A) is an initial state. In this state, the wire 15 is led out from the lower end of the capillary tool 13 and is cut by the cut clamper 16 above the capillary tool 13.
5, the wire 15 is fixed. 15 '
Indicates that chip 3 and substrate 2 were used in the previous wire bonding operation.
Are connected wires.

Next, as shown in FIG.
By applying a high voltage to the torch 19 approaching the lower end of the wire 15, an electric spark is generated between the lower end of the wire 15 and the tip of the torch 19, and the ball 20 is formed at the lower end of the wire 15. .

Next, as shown in FIG. 4 (c), the cut clamper 16 is opened to release the clamped state of the wire 15, and the capillary tool 13 is lowered so that the ball 2
0 is pressed against the external connection electrode on the upper surface of the chip 3 for bonding. Next, as shown in FIG. 5A, the capillary tool 13 is raised, and when it reaches the highest point, the cut clamper 16 is closed. Then, in this state, the capillary tool 13 is moved above the circuit electrode 5 of the substrate 2,
By lowering the lower end of the capillary tool 13 while drawing a predetermined locus, a loop of the wire 15 is formed.
As shown in (b), the wire 15 is pressed against the circuit electrode 5 of the substrate 2 and bonded.

Next, when the capillary tool 13 is raised and the wire 15 clamped by the cut clamper 16 is pulled up, the wire 15 is cut at the bonding point a. This completes the bonding at one bonding point, and then the same wire bonding operation is repeated for each bonding point.

In the above bonding operation, the wire cutting operation is repeated for each bonding point. As described above, the cut clamper 16 of the present embodiment reduces the impact of the cut clamp 16 on the wire during clamping. As a result, damage to the wire is prevented, so that defects in the bonding operation are reduced, and an efficient bonding operation can be realized.

[0023]

According to the present invention, the closing operation is performed by the clamp arm mechanism by driving the electric opening / closing driving means in the closing direction with a driving current value larger than the clamping current value corresponding to the predetermined clamping load in the clamping operation. After the operation, the electric opening / closing drive unit is driven in the opening direction to reduce the speed of the closing operation. After this deceleration step, the electric opening / closing drive unit is driven with the clamp current value so as to clamp the wire with a predetermined clamp load. Therefore, the impact on the wire at the time of clamping can be reduced without delaying the tact time of the entire clamping operation.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wire bonding apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view of a cut clamper of the wire bonding apparatus according to the embodiment of the present invention; FIG. 2B is a graph showing drive characteristics of the cut clamper of the wire bonding apparatus according to the embodiment of the present invention;

FIG. 3 is a graph showing a closing operation of a cut clamper of the wire bonding apparatus according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of an operation of the wire bonding apparatus according to the embodiment of the present invention;

FIG. 5 is an operation explanatory view of the wire bonding apparatus according to the embodiment of the present invention;

[Explanation of symbols]

 2 Substrate 3 Chip 13 Capillary tool 15 Wire 16 Cut clamper 21 First arm 22 Second arm 24 Stator 25 Coil 27 VCM drive unit 28 Control unit

Claims (1)

[Claims] 1. A method for controlling a wire clamp mechanism for clamping a wire fed to a capillary tool in a wire bonding apparatus for bonding a wire to a surface to be bonded, wherein a clamp arm mechanism for sandwiching the wire from both sides is electrically opened and closed. In a clamping operation for clamping the wire by opening and closing by a driving unit, a clamp arm mechanism is provided by driving the electric opening and closing driving unit in a closing direction with a driving current value larger than a clamp current value corresponding to a predetermined clamp load. A first closing step of causing the motor to perform a closing operation; a deceleration step of reducing the speed of the closing operation by driving the electric opening and closing driving means in an opening direction following the first closing step; Means is driven with the clamp current value to clamp the wire with a predetermined clamp load. The method of the wire clamping mechanism in a wire bonding apparatus which comprises a second closing step of writing.