JPH10270489A - Wire clamping device of wire bonding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire clamping device which can suitably clamp a wire even in a high temperature environment and can simplify the structure of an open/close driving unit. SOLUTION: A wire clamping device 20 in a wire bonding apparatus is arranged so that a pair of clamp arms 25 for grasping a wire can be opened or closed by the opening or closing actuation of an open/close driving unit 28 through a pushing block 27. The driving unit 28 has a magnetostriction member 30 expandingly or contractingly deformed parallel to a magnetic field direction by a change in a magnetic field to apply a pushing force to the pushing block 27, and also has a coil 31 for applying the magnetic field to the magnetostrictive member 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wire clamping device for a wire bonding device.

[0002]

2. Description of the Related Art In a wire bonding apparatus, a discharge is generated between a wire protruding from a capillary at a tip of a bonding arm and a torch electrode to form a ball at the tip of the wire, and the ball is bonded to an electrode of a semiconductor pellet (first electrode). 1
After the bonding, the capillary is moved onto the lead of the lead frame while the wire is led out, the wire is bonded to the lead (second bonding), and then the wire is cut, and the electrode and the lead are electrically connected by the wire. Is to be connected to.

[0003] After the wire bonding, the wire is cut by separating the wire clamp device from the lead together with the bonding arm while the wire clamp device holds the wire.

As shown in FIG. 5, in a conventional wire clamp device 101, a pair of clamp arms 103 capable of holding a wire (not shown) is opened and closed by an expansion and contraction of an opening and closing drive unit 105 through a pressing piece 104. It is configured to be. The opening / closing drive unit 105 is configured by laminating a plurality of piezoelectric elements 106 having a shape change due to dielectric polarization.

As shown in FIG. 6, by applying a voltage from a power supply 109 to a positive electrode 107 and a negative electrode 108,
Each piezoelectric element 106 of the opening / closing drive unit 105 undergoes dielectric polarization, and extends in the direction of arrow a in FIGS. 5 and 6 to close the clamp arm 103. In addition, when the power supply from the power supply 109 to the positive electrode 107 and the negative electrode 108 is cut off, the piezoelectric element 106 contracts and returns to its original length, and the elastic force of the spring 110 causes the clamp arm 103 to open.

[0006]

The above-described wire bonding by the wire bonding apparatus is performed under heating by a heater provided at a bonding position of the wire bonding apparatus. For this reason, the wire clamp device arranged above the heater is set to a high temperature of about 130 ° C. by the heat of the heater.

The upper limit (Curie temperature) of the ambient temperature at which the piezoelectric element 106 constituting the opening / closing drive unit 105 can exhibit a predetermined shape change rate is as low as 145 ° C. in the case of lead zirconate titanate. Under the high temperature state, the shape change is not stable, and there is a possibility that the opening and closing operation of the clamp arm 103 cannot be performed well.

The open / close drive unit 105 using the piezoelectric element 106 has a structure in which a positive electrode 107 and a negative electrode 108 are interposed between a plurality of piezoelectric elements 106 as shown in FIG. , The structure is complicated.

SUMMARY OF THE INVENTION The object of the present invention has been made in view of the above-mentioned circumstances, and it is possible to satisfactorily clamp a wire even in a high-temperature environment and to simplify the structure of an opening / closing drive unit. Is to provide.

[0010]

According to a first aspect of the present invention, there is provided a wire clamp apparatus for a wire bonding apparatus having a pair of clamp pieces and an open / close drive member for driving the clamp pieces to open / close. Has a magnetostrictive member that expands and contracts in accordance with the magnitude of a magnetic field, and magnetic field generating means that applies a magnetic field to the magnetostrictive member.

According to a second aspect of the present invention, in the first aspect of the invention, the opening / closing drive member includes a pressing member for applying a compressive pressure as a preload to the magnetostrictive member in a direction in which the magnetostrictive member expands and contracts. Have

The first aspect of the invention has the following operation. The opening / closing drive unit includes a magnetostrictive member that expands and contracts due to a change in a magnetic field.
Is higher than the Curie temperature of the piezoelectric element, so that it can be appropriately expanded and contracted even in a high-temperature environment. As a result, the wire can be satisfactorily clamped even in a high temperature environment.

The second aspect of the invention has the following operation. Since the opening / closing drive unit includes a preload member that applies a compressive stress to the magnetostrictive member as a preload, the gradient of the magnetostriction (shape change rate) in the magnetostrictive member can be made sensitive to the magnetic field. As a result, the opening / closing operation of the wire clamp device can be performed. Responsiveness can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. [A] First Embodiment FIG. 1 is a side view showing a wire bonding apparatus to which a first embodiment of a wire clamping apparatus of a wire bonding apparatus according to the present invention is applied. FIG. 2 is a plan sectional view of the wire clamp device of FIG.

The wire bonding apparatus 10 shown in FIG.
Is a lead (not shown) of the lead frame 9 on which the semiconductor pellet 8 is mounted in the previous step (second bonding point)
And an electrode (first bonding point) (not shown) of the semiconductor pellet 8 is electrically connected (bonded) by a wire 11.

The wire bonding apparatus 10 has a pair of guide rails 12 for transporting and guiding the lead frame 9 by using a frame feed clamper (not shown). An XY table 13 movable in the transport direction 9 and a direction orthogonal thereto is arranged.
3, a bonding head 14 is mounted.

The bonding head 14 has a capillary 15 through which the wire 11 is inserted through its head frame 14A.
And a torch electrode (not shown). The bonding arm 16 is vertically swung by an arm driving mechanism (not shown). The tip of the torch electrode is positioned directly below the capillary 15 by a torch drive mechanism (not shown) during discharge.

A heater 17 is provided between the pair of guide rails 12 at a bonding position immediately below the capillary 15. The heater 17 allows the guide rail 12
The semiconductor pellet 8 and the lead frame 9 which have been guided to the bonding position and are heated are heated, and first and second bonding described later are performed under a high temperature state.

The wire bonding apparatus 10 generates a discharge between the wire 11 protruding from the tip of the capillary 15 and the torch electrode, so that a ball 11a
Is formed, and the bonding arm 16 is rotated downward,
The ball 11a is bonded to the electrode of the semiconductor pellet 8 (first bonding). Thereafter, the bonding arm 16 is rotated upward, and the capillary 15 is moved onto the lead of the lead frame 8 while the wire 11 is led out. By rotating the bonding arm 16 downward, the wire 11 is bonded to the lead (second bonding). Thereafter, when the bonding arm 16 is pivoted upward, the capillary 15 rises while the wire 11 is drawn out. During the ascent, the wire clamp device 10 grips the wire 11 at a predetermined timing, and thereby the wire 11 Is cut in the vicinity of the joining portion, and a wire having a predetermined tail length is formed to project from the tip of the capillary 15. Thus, the wire bonding apparatus 10 electrically connects the electrodes of the semiconductor pellet 8 and the leads of the lead frame 9 with the wires 11.

As shown in FIG. 2, the wire clamp device 20 includes a pair of operating portions 23 integrally formed on a base portion 21 via a fulcrum portion 22 having a thin structure, and a clamp fixed to each of the operating portions 23. A pair of clamp arms 25 each having a piece 24, a pressing portion 18 integrally formed on both the operating portions 23 via a bridge portion 26, a pressing piece 27 fixed to the pressing portion 18, and a base portion 21. An opening / closing drive unit 28 serving as an opening / closing drive member interposed between the pressure member 27 and the pressing piece 27; and a spring 29 locked by the pair of operating portions 23 to provide a resilient force in a direction of approaching both operating portions 23. ,
Is configured.

The opening / closing drive unit 28 is provided with a magnetostrictive member 30 made of a magnetostrictive material which expands and deforms in parallel with the direction of the magnetic field when the magnetic field increases, and is disposed on the outer periphery of the magnetostrictive member 30 and connected to a power supply 32. It has a coil 31 as a magnetic field generating means.

The magnetostrictive member 30 has a unitary structure. The base end 30A is fixed to the base 21 and the front end 30B can be brought into contact with the pressing piece 27. Based on the base 30A. A pressing force can be applied to the pressing piece 27 by extension deformation in the direction of arrow A. Further, the coil 31 generates a magnetic field parallel to the longitudinal direction of the magnetostrictive member 30 by power supply from the power supply 32.

When a voltage is applied from the power supply 32 to the coil 31 and the magnetic field in the coil 31 increases, the magnetostrictive member 30 of the opening / closing drive unit 28 expands and deforms in the direction of arrow A, and this expanding operation is transmitted to the pressing piece 27. Thus, the pressing piece 27 presses the pair of operating parts 23 via the pressing part 18. As a result, the operating portion 23 is pushed and expanded around the fulcrum portion 22 against the resilient force of the spring 29, the pair of clamp arms 25 open in the direction of arrow M, and the wire clamp device 20
The gripping of the wire 11 by both clamp pieces 24 is released.

When the power supply from the power supply 32 to the coil 31 is cut off and the magnetic field in the coil 31 decreases, the magnetostrictive member 30 of the opening / closing drive unit 28 contracts and deforms in the direction of arrow B with respect to the base end 30A. Then, the shape returns to the original shape, and the action of the pressing force from the magnetostrictive member 30 to the pressing piece 27 is released.
As a result, the pair of operating portions 23 approach each other due to the elastic force of the spring 29, the clamp arm 25 closes in the direction of the arrow N, and the wire clamp device 20 grips the wire 11 with both clamp pieces 24.

Here, the magnetostrictive material constituting the magnetostrictive member 30 is pure nickel (pure Ni), iron / nickel alloy (Fe
-Ni-based alloy), iron-cobalt-based alloy (Fe-Co-based alloy), ferrite (iron oxide) added with nickel, zinc, or the like, or an alloy of a rare earth element and iron. An alloy of a rare earth element and iron is, for example, a terbium-iron alloy (TbF
e ₂ ), dysprosium-iron-based alloy (DyFe ₂ ), samarium-iron-based alloy (SmFe ₂ ), holmium-iron-based alloy (HoFe ₂ ), erbium-iron-based alloy (ErFe
₂ ) and the like, and in particular, a terbium-dysprosium-iron alloy (Tb _0.3 Dy _0.7 Fe ₂ ) is preferable. When the magnetostrictive material is a terium, dysprosium, or iron-based alloy, the upper limit (Curie temperature) of the ambient temperature at which a predetermined shape change rate can be exhibited is about 350 ° C. When the magnetostrictive material of the magnetostrictive member 30 is a terbium-dysprosium-iron alloy, the single shape change rate (magnetostriction) is 1500 to 2000 pp.
m. On the other hand, the open / close drive unit 1
05, for example, composed of lead zirconate titanate.
When 100 piezoelectric elements 106 are used, the shape change rate of the opening / closing drive unit 105 is several hundred ppm, and the magnetostrictive material has an order of magnitude better shape change rate.

According to the above embodiment, the following effects are obtained.
To play. The opening / closing drive unit 28 includes a magnetostrictive member 30 made of a magnetostrictive material that expands and deforms due to an increase in a magnetic field, and this magnetostrictive material exhibits a predetermined shape change rate in the case of, for example, a television, dysprosium, or iron-based alloy. The upper limit (Curie temperature) of the obtained environmental temperature is about 350 ° C., which is extremely higher than the Curie temperature of the piezoelectric element 106 made of, for example, lead zirconate titanate, which is 145 ° C., and therefore, the elongation deformation is stable even in a high temperature environment. Is obtained. As a result, the wire clamp device 20 using the opening / closing drive unit 28 is used.
Can satisfactorily clamp and release the wire 11 even in a high temperature environment.

The opening and closing drive unit 105 includes the piezoelectric element 10
6 requires a plurality of, for example, about 100, piezoelectric elements 106. Of course, the positive electrodes 107 and the negative electrodes 108 must be alternately arranged between the piezoelectric elements 106. The structure of the drive unit 105 is complicated. On the other hand, in the opening / closing drive unit 28 provided with the magnetostrictive member 30 of the present invention, the magnetostrictive member 30 has a single structure, and the solenoid 31 may be arranged on the outer periphery of the magnetostrictive member 30, so that the structure can be simplified. .

Since the opening / closing drive unit 28 of the wire clamp device 20 has a magnetostrictive member made of a magnetostrictive material, especially when the magnetostrictive material is a terbium-dysprosium-iron-based alloy, a conventional type is used. For example, the rate of change in shape of the piezoelectric element 106 made of lead zirconate titanate is extremely large at 1500 to 2000 ppm as compared with several hundred ppm.
As a result, the wire clamp device 20 can satisfactorily open and close the clamp arm 25 to clamp and release the wire 11.

[B] Second Embodiment FIG. 3 is a plan view of a wire clamp device showing a second embodiment of the wire clamp device of the wire bonding device according to the present invention. FIG. 4 is a plan sectional view showing the opening / closing drive unit of FIG. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIGS. 3 and 4, the opening / closing drive unit 43 of the wire clamp apparatus 40 includes a magnetostrictive member 30.
And the solenoid 31 are accommodated in a unit case 41, and the unit case 41 is
7 is interposed. A base end portion 30A of the magnetostrictive member 30 is fixed to one end surface of the unit case 41, and a small-diameter front end portion 30C protrudes outward from the other end surface of the unit case 41, and the front end portion 30C contacts the pressing piece 27. It is possible.

Further, the tip portion 30C of the magnetostrictive member 30
A disc spring 42 as a pressing member is interposed between the side step 30D and the other end surface of the unit case 41. The disc spring 42 applies a compressive stress as a preload in the direction of expansion and contraction of the magnetostrictive member 30. This compressive stress is, for example, 0.7 to 1.
About 4 kgf / mm ² is preferable.

As described above, since the compressive stress is applied to the magnetostrictive member 30 from the disc spring 42 as a preload, the wire clamp device 40 includes the wire clamp device 2 described above.
The following effects are exhibited in addition to the effect of 0.

Since the compressive stress is applied to the magnetostrictive member 30 from the disc spring 42 as a preload, when the magnetic field acting on the magnetostrictive member 30 changes, the gradient of the shape change rate (magnetostriction) of the magnetostrictive member 30 changes with respect to the magnetic field. The wire clamping device 4 becomes sensitive to a clamping signal from a control device (not shown).
0, the response of the opening and closing operation is improved, and the capillary 15
The variation of the tail length of the wire derived from the above can be prevented as much as possible.

That is, during the bonding operation of the wire bonding apparatus 10 as described above, the capillary 1 after the wire 11 is connected to the lead of the lead frame 9.
The wire clamp device 40 grips the wire 11 at a predetermined timing during the ascent of the wire 5, thereby cutting the wire 11 near the joint to the lead, and forming a wire having a predetermined tail length at the tip of the capillary. ing.
During the gripping operation of the wire clamp device 40, it takes a time ΔT from when the control device issues a clamp signal (close signal) to when the wire clamp device 40 actually grips the wire 11. Therefore, a clamp signal is transmitted from the control device to the wire clamp device 40 at a timing earlier by the time ΔT than the capillary 15 reaches the height at which the wire 11 of the predetermined length is led out from the tip thereof. You. However, there is some variation in the rising speed of the capillary 15, and when the rising speed of the capillary 15 varies between the time when the clamp signal is transmitted from the control device and the time when the wire clamp device 40 grips the wire 11, This causes a problem that the tail length varies. However, as described above, the time ΔT is shortened due to the good responsiveness of the opening / closing operation of the wire clamp device 40, and as a result, the timing closer to the timing at which the wire 11 of the predetermined length is led out from the capillary 15 Thus, the clamp signal can be transmitted from the control device, and the influence of the variation in the rising speed of the capillary 15 is reduced. Therefore, variation in the tail length of the wire 11 derived from the capillary 15 can be prevented as much as possible.

In the above embodiments, the magnetostrictive member 30 is used.
Although a magnetostrictive material that expands and deforms with an increase in the magnetic field is used, a magnetostrictive material that contracts in the magnetic field direction with an increase in the magnetic field may be used. Further, a permanent magnet may be used as the magnetic field generating means, and the permanent magnet may be moved with respect to the magnetostrictive member 30. Further, a leaf spring, a coil spring, an elastic body, or the like may be used as the preload member.

[0036]

As described above, according to the wire clamping device of the wire bonding device according to the present invention, it is possible to satisfactorily clamp the wire even in a high temperature environment and to simplify the structure of the opening / closing drive unit.

[Brief description of the drawings]

FIG. 1 is a side view showing a wire bonding apparatus to which a first embodiment of a wire clamping apparatus of a wire bonding apparatus according to the present invention is applied.

FIG. 2 is a plan sectional view of the wire clamp device of FIG. 1;

FIG. 3 is a plan sectional view of the wire clamp device showing a second embodiment of the wire clamp device of the wire bonding device according to the present invention.

FIG. 4 is a sectional view showing the opening / closing drive unit of FIG. 3;

FIG. 5 is a plan sectional view showing a conventional wire clamp device.

FIG. 6 is a sectional view showing the opening / closing drive unit of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wire bonding apparatus 11 Wire 15 Capillary 16 Bonding arm 20 Wire clamp apparatus 24 Clamp piece 25 Clamp arm 27 Pressing piece 28 Opening / closing drive unit 30 Magnetostrictive member 31 Coil (magnetic field generating means) 32 Power supply 40 Wire clamp apparatus 42 Disc spring (Pressurization) 43) Opening / closing drive unit

Claims (2)

[Claims] 1. A wire clamp device for a wire bonding apparatus having a pair of clamp pieces and an opening and closing drive member for opening and closing the clamp pieces, wherein the opening and closing drive member expands and contracts in accordance with the magnitude of a magnetic field. A wire clamping device for a wire bonding device, comprising: a member; and a magnetic field generating means for applying a magnetic field to the magnetostrictive member. 2. The opening / closing drive member, wherein:
2. The wire clamping device according to claim 1, further comprising a pressurizing member for applying a compression pressure as a preload in a direction in which the magnetostrictive member expands and contracts.