JP2000353719A - Wire clamp mechanism in wire bonding equipment - Google Patents

Abstract

(57) [Problem] To provide a wire clamping mechanism in a wire bonding apparatus which does not cause a problem even at a high speed operation. SOLUTION: In a wire clamping mechanism for clamping a wire fed to a capillary tool of a wire bonding apparatus, a first mechanism for sandwiching the wire from both sides is provided.
Piezoelectric elements 24A and 24B that respectively open and close the first arm member 21A and the second arm member 21B. The first and second arm members 21A and 24B are controlled by a piezoelectric element control unit 25. The phase of the opening / closing operation of the second arm member 21B is shifted. Thereby, it is possible to reduce the impact at the time of the closing operation and prevent damage to the wire. First,
The same effect can be obtained by changing the mass distribution of the second arm member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wire clamping mechanism and a wire bonding apparatus 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 two clamp arms to open and close, 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 is excessive, damage such as crushing or scratching of the wire occurs, and the wire cannot be cut normally at the bonding point when the wire is pulled up, which may cause a problem. 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 wire clamping mechanism in a wire bonding apparatus which does not cause a problem even at a high speed operation.

[0005]

According to a first aspect of the present invention, there is provided a wire bonding mechanism for bonding a wire fed to a capillary tool in a wire bonding apparatus for bonding a wire to a surface to be bonded. A first arm member and a second arm member for sandwiching the wire from both sides, and a first driving unit and a second driving unit for opening and closing the first arm member and the second arm member, respectively. A drive unit; and a phase control unit that controls these drive units to shift the phase of the closing operation of the first arm member and the second arm member.

According to a second aspect of the present invention, there is provided a wire bonding 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. A first arm member and a second arm member respectively sandwiched from both sides, a single drive unit for opening and closing the first arm member and the second arm member, and a displacement of the drive unit by the first arm There is provided phase conversion means for shifting the phase of the closing operation between the first arm member and the second arm member when transmitting to the member and the second arm member.

According to a third aspect of the present invention, there is provided a wire bonding 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. A first arm member and a second arm member which are respectively sandwiched from both sides; and a single drive unit for opening and closing the first arm member and the second arm member. By changing the mass distribution of the second arm member, the natural frequencies of the first arm member and the second arm member are made different.

According to a fourth aspect of the present invention, in the wire clamping mechanism of the wire bonding apparatus, at least one of the first arm member and the second arm member includes a plurality of separate parts. A wire clamp mechanism in the wire bonding apparatus described in the above.

According to a fifth aspect of the present invention, there is provided a wire bonding apparatus for bonding a wire to a surface to be bonded by a capillary tool, wherein a wire clamp mechanism for clamping a wire fed to the capillary tool is provided. A wire clamp mechanism in wire bonding according to any one of claims 1 to 4.

According to the present invention, in the opening and closing operation of the first arm member and the second arm member respectively sandwiching the wire from both sides of the wire clamp mechanism for clamping the wire fed to the capillary tool, By shifting the phase of the opening / closing operation of the first arm member and the second arm member or changing the mass distribution of the first arm member and the second arm member. By making the frequency different,
The impact at the time of the closing operation can be reduced to prevent damage to the wire.

[0011]

(Embodiment 1) FIG. 1 is a perspective view of a wire bonding apparatus according to Embodiment 1 of the present invention, and FIG.
FIG. 3A is a plan view of a cut clamper of the wire bonding apparatus, FIG. 3A is a plan view of a cut clamper of the wire bonding apparatus, FIG. 3B is a side view of the cut clamper of the wire bonding apparatus, and FIG. 4) is a plan view of a cut clamper of the wire bonding apparatus, and FIG.
5 is a partially enlarged view of a cut clamper of the wire bonding apparatus, FIGS. 5 and 6 are explanatory diagrams of the wire bonding operation, and FIG. 9A is a graph showing a closing operation of the clamp arm.

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 external connection electrodes of the chip 3 and the circuit electrodes 5 are connected by wires.

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 into 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 for clamping the wire. A torch 19 is provided near the lower end of the capillary tool 13. Torch 19
Generates a metal ball at the lower end of the wire 15 by generating a spark between 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, a wire clamp mechanism of the wire clamper 16 for clamping a wire above the capillary tool will be described with reference to FIG. In FIG. 2, the wire clamper 16 includes a base 20 for fixing the wire clamper to the main body.
A (first arm member) and second clamp arm 21
B (second arm member) extends in the same direction. First clamp arm 21A and second clamp arm 2
1B is partially thinned to form leaf spring portions 22A and 22B.
In the vicinity of A and 22B, contact portions 23A and 23 protruding inward are provided.
3B is provided.

The piezoelectric elements 24A and 24B are in contact with the contact portions 23A and 23B, respectively.
By applying a positive voltage to the contact portions 23A and 23B,
B is displaced in the direction of the arrow.
A and 22B are bent. Thereby, the first clamp arm 21A and the second clamp arm 21B are displaced in the direction of the arrow, and the pad 27 attached to the distal end is opened. When the voltage application to the piezoelectric elements 24A and 24B is released, the first clamp arm 21A and the second clamp arm 21B are displaced in the opposite direction as described above, and the pad 27 at the distal end performs the closing operation. That is, the piezoelectric element 24
Reference numerals A and 24B denote first driving means and second driving means for opening and closing the first clamp arm 21A and the second clamp arm 21B, respectively.

The piezoelectric elements 24A and 24B are driven by a piezoelectric element driving section 25. The piezoelectric element driving unit 25 includes a delay circuit that sets a time difference between the operation timings of the piezoelectric elements 24A and 24B. When the piezoelectric elements 24A and 24B are driven by a command from the control unit 26, the piezoelectric element 24A A delay time is set from the start of the operation to the start of the operation of the piezoelectric element 24B.

The significance of the delay time will be described with reference to FIG. FIG. 9 shows the time change of the displacement of the distal end of the clamp arm when the cut clamper is closed. The displacement of the first clamp arm 21A is shown on the upper side of the time axis, and the second clamp is shown on the lower side. This shows the displacement of the arm 21B. When a positive voltage is applied to the piezoelectric element 24A, the distal end of the first clamp arm 21A starts displacing downward (closed direction). Then, after the time difference t, the piezoelectric element 24B
Is applied with a positive voltage. As a result, the second clamp arm 21B starts displacing upward (closed direction). That is, in the closing operation of the first clamp arm 21A and the second clamp arm 21B, the phases are shifted by a time difference t as shown in FIG. 9A. That is, the piezoelectric element driving unit 25 and the control unit 26 serve as phase control means for shifting the phase of the closing operation of the first clamp arm 21A and the second clamp arm 21B.

When the distal ends of the first clamp arm 21A and the second clamp arm 21B approach each other due to the phase shift and clamp the wire, one clamp arm is displaced in the closing direction. At this time, the clamp arm on the opposite side is displaced in the opening direction, and the relative speed between the first clamp arm 21A and the second clamp arm 21B decreases. Therefore, the impact given to the wire during clamping can be reduced to prevent damage. At this time, since the speed itself of the clamping operation itself does not need to be reduced, it is possible to prevent the occurrence of wire damage during clamping while performing a high-speed bonding operation.

FIG. 3 shows another example of the first embodiment. The above-described embodiment is provided with separate driving means for each of the first clamp arm 21A and the second clamp arm 21B.
While a phase shift is set in the closing operation of the second clamp arm 21B, the present embodiment is to obtain a similar phase shift by a single driving unit. 3A, a first clamp arm 31A and a second clamp arm 31B extend from a base 20 'similar to the cut clamper 16 shown in FIG. 2 in the cut clamper 16'. The base portions of the first clamp arm 31A and the second clamp arm 31B are partially thinned to form leaf spring portions 32A and 32B, respectively.
Contact portions 33A and 33B are provided outside the plate spring portions 32A and 32B and separated by notches.

A piezoelectric element 28 is disposed near the contact portions 33A and 33B, and a transmission member 29 is interposed between the contact portions 33A and 33B and the piezoelectric element 28. Here, the thickness of the transmission member 29 differs depending on the contact portions 29A and 29B with the contact portions 33A and 33B, and the transmission member 2 has a negative voltage applied to the piezoelectric element 28.
The contact portion 29A of No. 9 contacts the contact portion 33A and the piezoelectric element 28, and in this state, the dimensions are set so that a predetermined clearance C is generated between the contact portion 29B and the contact portion 33B. In this state, the dimensions of each part of the cut clamper are set so that a compressive stress acts on the piezoelectric element 28, and the distal ends of the first clamp arm 31A and the second clamp arm 31B are opened. I have.

FIG. 4A shows a state where the application of the negative voltage to the piezoelectric element 28 is released. In this state, the length of the piezoelectric element 28 is extended, and therefore, the contact portions 33A, 33B
Are both displaced in the direction of the arrow. And the leaf spring part 32
A, 32B flexes, causing the first clamp arm 3
The distal ends of the first and second clamp arms 31B are displaced in the closing direction. Here, as shown in FIG. 4B, the point of action P1 of the pressing force acting on the contact portion 33, the leaf spring portion 32
The stroke at the time of the closing operation can be set by appropriately setting the mutual positional relationship between the center point P2 of the deflection of the clamp arm and the clamp point P3 at the tip of the clamp arm. That is, by increasing the lever ratio of the distance l2 between P2 and P3 to the distance l1 between P1 and P2, a large stroke of the closing operation can be obtained with the same displacement of the piezoelectric element, and the second clamp arm 32B Even when only the clearance C is provided, the two clamp arms can be correctly closed on the central axis.

In this closing operation, since the transmission member 29 has a different thickness depending on the contact portions 29A and 29B,
The timing at which the first clamp arm 31A and the second clamp arm 31B start the closing operation is different, and a phase shift occurs in the closing operation. That is, the transmission member 29 is
When transmitting the displacement of the piezoelectric element 28 to the first clamp arm 31A and the second clamp arm 31B, it serves as a phase conversion means for shifting the phase of the closing operation. The cut clamper 16 'can also shift the phase at the time of the closing operation as described with reference to FIG. 9A, and can reduce the impact on the wire at the time of clamping similarly to the cut clamper 16 described above. .

This wire bonding apparatus has the above configuration, and its operation will be described below with reference to FIGS. 5 (a) to 5 (c) and FIG. 6 (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 the wire 15 is clamped by the clamper 16 above the capillary tool 13 to fix the wire 15. . Reference numeral 15 'denotes a wire connecting the chip 3 and the substrate 2 in the previous wire bonding operation.

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.
6, the wire 15 is released from the clamped state, and the capillary tool 13 is lowered to press the ball 20 against the external connection electrode on the upper surface of the chip 3 for bonding. Next, as shown in FIG. 6A, the capillary tool 13 is raised, and when the capillary tool 13 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, and the lower end of the capillary tool 13 is lowered while drawing a predetermined locus to form a loop of the wire 15, and FIG. The wire 15 is pressed against the circuit electrode 5 of the substrate 2 for bonding as shown in FIG.

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 at each bonding point. As described above, in the wire clamper of the present embodiment, the impact on the wire by the clamp arm at the time of wire clamping is reduced. In addition, since damage to the wire is prevented, problems in the bonding operation are reduced, and an efficient bonding operation can be realized.

(Embodiment 2) FIGS. 7 and 8 are plan views of a cut clamper of a bonding apparatus according to Embodiment 2 of the present invention, and FIG. 9B is a graph showing a closing operation of the clamp arm. In the present embodiment, the operation timing at the time of the clamp operation is shifted by providing a mass difference between the two clamp arms for clamping the wire and changing the mass distribution. 7, the clamp arm 36 has a base 40 similar to that in the first embodiment,
A first clamp arm 41A and a second clamp arm 41B extend from the base 40. The root portions of the first clamp arm 41A and the second clamp arm 41B are partially thinned to form leaf spring portions 39A and 39B, respectively, and the leaf spring portions 39A and 39B are formed.
A contact portion 38 is provided inside B.

The piezoelectric element 37 is in contact with the contact part 38. When a positive voltage is applied to the piezoelectric element 37, the contact part 38 is displaced in the direction of the arrow, and the leaf spring parts 22A and 22B are bent. Occurs. Thereby, the first clamp arm 41
A and the distal end of the second clamp arm 41B perform an opening operation. Therefore, the piezoelectric element 37 serves as a driving unit for opening and closing the first clamp arm 41A and the second clamp arm 41B.

Here, the first clamp arm 41A and the second clamp arm 41B have different sizes and different mass distributions. Accordingly, when the first clamp arm 41A and the second clamp arm 41B are driven by the piezoelectric element 37 to perform the closing operation, the natural frequencies thereof are different from each other, and as shown in FIG.
The closing operation is performed based on different vibration periods T1 and T2. For this reason, the first clamp arm 41A and the second clamp arm 41B do not close at the same timing, and similarly to the case where a phase shift is provided in the closing operation in the above-described first embodiment, the time of clamping is not increased. The impact on the wire can be reduced.

FIG. 8 shows another example of the second embodiment. Also in this embodiment, as described above,
By providing a mass difference between the two clamp arms, the timing of the closing operation of the clamp arms is intended to be shifted. In FIG. 8, the clamp arms are first and second clamp arms 51 </ b> A and 51 </ b> B from the base 50 as in the present embodiment.
Is provided to extend. First clamp arm 51
The base portions of the arm A and the second clamp arm 51B are provided with cutouts 53A and 53B, respectively, to form leaf springs 52A and 52B, and the leaf springs 52A and 52B are brought into contact with 54A and 54B. Is linked to

A piezoelectric element 55 is in contact with the contact portions 54A and 54B. When the piezoelectric element 55 is driven, the contact portions 54A and 54B are displaced in the direction of the arrow, and
A and 52B are bent. Thereby, the first clamp arm 51A and the second clamp arm 51B perform opening and closing operations. The notch 5 is formed in the contact portions 54A and 54B.
6 is formed, and a preload can be applied to the piezoelectric element 55 by applying a pressing load to the notch portion 56 with a bolt 57.

Here, the second clamp arm 51B is formed by fastening a separate part 51C, and the first clamp arm 51A and the second clamp arm 51B have different mass distributions. As a result, the natural frequencies of the first clamp arm 51A and the second clamp arm 51B are different from each other as in the example shown in FIG. 7, and the impact on the wire during clamping is reduced as in the first embodiment. can do. Thus, by configuring at least one clamp arm as a separate component,
The material can be partially changed, and a desired mass distribution can be easily obtained.

In the first and second embodiments, a piezoelectric element is used as the driving means for driving the opening / closing operation of the clamp arm. However, the present invention is not limited to this. May be used.

[0037]

According to the present invention, there is provided a wire clamping mechanism for clamping a wire fed to a capillary tool.
In the opening / closing operation of the first arm member and the second arm member sandwiching the wire from both sides, the phase of the opening / closing operation of the first arm member and the second arm member is shifted, so that the closing operation The impact can be reduced to prevent damage to the wire. Also,
The same effect can be obtained by changing the natural frequency of the first arm member and the second arm member by changing the mass distribution of the first arm member and the second arm member.

[Brief description of the drawings]

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

FIG. 2 is a plan view of a cut clamper of the wire bonding apparatus according to the first embodiment of the present invention.

FIG. 3A is a plan view of a cut clamper of the wire bonding apparatus according to the first embodiment of the present invention. FIG. 3B is a side view of a cut clamper of the wire bonding apparatus according to the first embodiment of the present invention.

4A is a plan view of a cut clamper of the wire bonding apparatus according to the first embodiment of the present invention. FIG. 4B is a partially enlarged view of the cut clamper of the wire bonding apparatus according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a wire bonding operation according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a wire bonding operation according to the first embodiment of the present invention.

FIG. 7 is a plan view of a cut clamper of the wire bonding apparatus according to the second embodiment of the present invention.

FIG. 8 is a plan view of a cut clamper of the wire bonding apparatus according to the second embodiment of the present invention.

9A is a graph showing a closing operation of the clamp arm according to the first embodiment of the present invention. FIG. 9B is a graph showing a closing operation of the clamp arm according to the second embodiment of the present invention.

[Explanation of symbols]

2 Substrate 3 Chip 12 Horn 13 Capillary tool 15 Wire 16 Cut clamper 21A, 31A, 41A, 51A First clamp arm 21B, 31B, 41B, 51B Second clamp arm 24A, 24B, 28, 37, 55 Piezoelectric element 25 Piezoelectric element drive unit 29 Transmission member

Claims (5)

[Claims] 1. A wire clamping 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 the first arm member and the second arm member respectively sandwich the wire from both sides. , A first driving unit and a second driving unit that respectively open and close the first arm member and the second arm member, and a first arm member that controls these driving units. A wire clamp mechanism in a wire bonding apparatus, comprising: a phase control unit that shifts a phase of a closing operation of a second arm member. 2. A wire clamping 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 the first arm member and the second arm member respectively sandwich the wire from both sides. Arm member, a single drive unit for opening and closing the first arm member and the second arm member, and transmitting a displacement of the drive unit to the first arm member and the second arm member. A wire clamp mechanism in a wire bonding apparatus, comprising: a phase converter that shifts a phase of a closing operation between a first arm member and a second arm member. 3. A wire clamping 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 the first arm member and the second arm member respectively sandwich the wire from both sides. And a single drive means for opening and closing the first arm member and the second arm member. The first arm member and the second arm member
A wire clamp mechanism in a wire bonding apparatus, wherein the natural frequencies of the first arm member and the second arm member are changed by changing the mass distribution of the arm member. 4. The wire clamping mechanism according to claim 3, wherein at least one of said first arm member and said second arm member is formed of a plurality of separate parts. 5. A wire bonding apparatus for bonding a wire to a surface to be bonded by a capillary tool, wherein a wire clamp mechanism for clamping a wire fed to the capillary tool is provided. 3. A wire bonding apparatus comprising a wire clamp mechanism in wire bonding according to 1.