JP2000158375A - Manipulator head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a change in an opening/closing stroke and clamping pressure without practically causing heating of a coil and the thermal expansion of a super magnetostrictive element caused by this even if a manupulator head is continuously used for many hours. SOLUTION: A super magnetostrictive actuator 3 for opening/closing a pair of fingers 2R, 2L has a coil 7, a super magnetostrictive element 8 arranged in the center and a yoke arranged outside the coil 7, and a closed magnetic circuit for passing a magnetic flux generated by the coil 7 is formed of the super magnetostrictive element 8 and the yoke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manipulator head which opens and closes a finger for gripping a work by a giant magnetostrictive actuator, and more particularly to a wire clamper of a bonding machine for wire bonding between an electrode such as a semiconductor element and an external lead terminal. It is suitable for use in

[0002]

2. Description of the Related Art A wire bonding machine is for electrically connecting a semiconductor element to a lead frame and then electrically connecting the semiconductor element and an electrode formed on the lead frame with a very fine gold wire. As shown in the figure, a guide 43 for guiding the gold wire 42 wound around the spool 41
A capillary 44 for inserting and holding the gold wire 42;
Wire clamper 4 for clamping 2 at a predetermined timing
5, the capillary 44 and the wire clamper 45
Are integrally attached to the robot arm and can move in the XYZ directions.

When wire bonding is performed between the electrode 47 of the semiconductor element 46 and the external lead terminal 48 using this bonding machine, first, the tip of the gold wire 42 is passed through a capillary 44 to a predetermined length, and The wire clamper 45 is closed and the gold wire 42 is fixed.

Then, a discharge is caused at the tip of the gold wire 42 to melt the gold wire 42 to form a ball-shaped droplet.
In this state, the capillary 44 is connected to the electrode 47 of the semiconductor element 46.
Then, the droplet is pressed against the electrode 47 to perform the first bonding.

Next, with the wire clamper 45 opened and the gold wire 42 separated, the capillary 44 is moved to the external lead terminal 48, and the gold wire 42 is pressed against the terminal 48 to perform second bonding.

Finally, the capillary 44 is raised, and the wire clamper 45 is closed in a state where the gold wire 42 is extended by a predetermined length from the tip of the capillary 44. When the capillary 44 is further raised, the gold wire 42 is pulled. Then, it is torn off from the external lead terminal 48, and the bonding operation for one electrode is completed. This is repeated one after another, and the bonding operation is continuously performed for each electrode.

[0007] The wire clamper 45 used in such a bonding machine is composed of a finger for removably holding the gold wire 42 and an actuator for opening and closing the finger. There are various types of actuators for opening and closing the fingers, but those using a push-pull solenoid coil have a slow response speed and a complicated structure, and those using a voice coil linear motor are large. The structure using the piezoelectric element has a complicated structure, and has a problem that the manufacturing cost is increased, the device is easily broken, and the reliability is low.

For this reason, the present applicant has experimentally manufactured a wire clamper that uses a giant magnetostrictive actuator that expands and contracts a bar-shaped giant magnetostrictive element in the axial direction by a magnetic field generated by a coil, and that opens and closes a finger by using the expansion and contraction deformation. Since this wire clamper opens and closes fingers with a giant magnetostrictive actuator, it can be manufactured small, light, and inexpensively, has a simple structure, does not easily break down, has a fast opening and closing response speed, and can be driven at low voltage. There is an advantage.

[0009]

However, in order to obtain a predetermined opening / closing stroke and a predetermined clamping pressure required as a clamper, it is necessary to supply a current to the coil to form a high magnetic field. When the step is repeated, the coil generates heat, the heat causes the giant magnetostrictive element to thermally expand, and the displacement is transmitted to the finger, causing a new problem in that the opening / closing stroke and the clamp pressure are changed.

For example, in order to pass a gold wire having a diameter of several tens of μm through the tip of the finger, a gap of about 100 μm must be formed at the time of opening, and a clamp of about 50 gf is required to tear the gold wire at the time of closing. There is. To satisfy this condition, using a coil formed by winding a copper wire having a wire diameter of 0.25 mm for 870 turns, a current of ± 0.6 A is obtained.
When energized at a frequency of 10 Hz (opening time 0.09 seconds, closing time 0.01 seconds), the coil surface temperature was 70-
The temperature rose to 80 ° C.

Therefore, in a clamper having a structure in which the finger is opened by extending the giant magnetostrictive element, the finger acts to open due to the thermal expansion of the giant magnetostrictive element, so that a sufficient clamping pressure can be obtained even if the gold wire is grasped. You will not be able to tear off the gold wire. Also, in a clamper having a structure in which the finger is closed by extending the giant magnetostrictive element, the finger acts to close due to the thermal expansion of the giant magnetostrictive element. Inconvenience such that it is not possible to pass through the space freely.

Accordingly, it is a technical object of the present invention to prevent the coil from generating heat even when used continuously for a long time and to prevent the opening / closing stroke and the clamping pressure from changing.

[0013]

In order to solve this problem, the present invention expands and contracts a bar-shaped giant magnetostrictive element in the axial direction by a magnetic field generated by a coil, and opens and closes a pair of fingers using the expansion and contraction deformation. In the manipulator head provided with a giant magnetostrictive actuator, the giant magnetostrictive actuator forms a closed magnetic circuit that passes a magnetic flux generated by the coil by the giant magnetostrictive element arranged at the center of the coil and the yoke arranged outside the coil. It is characterized by having been done.

According to the present invention, since the giant magnetostrictive element disposed at the center of the coil and the yoke disposed outside the coil form a closed magnetic circuit through which the magnetic flux generated by the coil passes, the entire magnetic field is reduced. At the same time as the resistance decreases, the leakage magnetic flux decreases, and the magnetic flux can efficiently act on the giant magnetostrictive element. Therefore, the performance required for the manipulator head can be obtained with a much smaller magnetomotive force than in the past, and the amount of current flowing through the coil can be reduced accordingly, and the amount of heat generation can be suppressed.

If the frame on which the giant magnetostrictive actuator is mounted is formed to have a T-shaped cross section having radiating fins protruding outward, not only can the heat transmitted to the frame be radiated to the outside air, but also the entire structure can be radiated. Since the weight is light, high-speed response is also excellent.

Further, if the yoke is formed in a substantially rectangular frame shape, the coil remains exposed to the outside air. Therefore, even if the coil generates heat to some extent, the heat is easily radiated, and the giant magnetostrictive element can be used. There is no effect until thermal expansion. Further, if the yoke is inclined at an arbitrary angle, the overall height of the manipulator head does not increase, and it is not necessary to expand the manipulator head in the width direction.

Further, the yoke is made of 45 permalloy,
If it is made of a high magnetic permeability material such as 50 permalloy, 78 permalloy, pure iron, silicon class, soft magnetic amorphous, directional silicon class, alpalm, sendust, supermalloy with Mo, supermalloy with Cu, the magnetic resistance can be reduced to the conventional value. It can be reduced to about 40%. Therefore,
The amount of heat generated can be further reduced by further reducing the current supplied to the coil.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an explanatory view showing a manipulator head according to the present invention, FIG. 2 is a sectional view taken along line AA, and FIG. 3 is an explanatory view showing a giant magnetostrictive actuator.

The manipulator head 1 according to the present embodiment is used, for example, as a wire clamper mounted on a robot arm of a wire bonding machine, and opens and closes a pair of left and right fingers 2R, 2L for gripping a wire and fingers 2R, 2L. Is provided.

The fingers 2R, 2L are provided with wire clamp pads 4R, 4L at the tips thereof, and the frame 5 on which the giant magnetostrictive actuator 3 is mounted is provided at the rear end thereof.
Are attached integrally.

The rear ends of the fingers 2R and 2L have a force point P _1.
Next, pads 4R tip, 4L is the point P _2, and the
Intermediate point connected to the frame 5 to form a leverage as a fulcrum P _3. Therefore, is super-magnetostrictive element 8 is extended by the super-magnetostrictive actuator 3 arranged in a frame 5, when the power point P ₁ is pressurized to the working point P ₂ direction, times to open outwardly about the fulcrum P ₃ Be moved. This finger 2R, 2
The L and the frame 5 are formed in a T-shaped cross section having outwardly protruding radiating fins 6 so that the radiating fins 6 enhance the heat radiation effect and reduce the weight without lowering the mechanical strength. .

On the other hand, the giant magnetostrictive actuator 3 has a coil
7, a bar-shaped giant magnetostrictive element 8 is arranged at the center of
While being pressed against the rear frame 5a of the frame 5,
After the fingers 2R and 2L via the push rod 9
Force point P formed at the end₁, And giant magnetostriction
When the element 8 is extended, the power point P₁Is the action point P _TwoMoved to the side
As described above, the finger 2
R and 2L open reliably.

The giant magnetostrictive actuator 3 includes the giant magnetostrictive element 8 and a yoke 10 arranged outside the coil 7.
Since the closed magnetic circuit is formed by (1) and (2), the magnetic field generated by the coil 7 passes through the giant magnetostrictive element 8 and the yoke 10, and the magnetic resistance of the magnetic circuit can be reduced.

The yoke 10 is made of 45 permalloy, 50
Permalloy, 78 permalloy, pure iron, silicon steel, soft magnetic amorphous, directional silicon steel, alpalm, sendust, Mo-containing supermalloy, Cu-containing supermalloy, etc., have a maximum relative magnetic permeability of 1000 or more, more preferably 50 or more.
It is formed of an alloy of 00 or more.

The yoke 10 includes a substantially U-shaped lower frame 10A which is in contact with the rear end of the giant magnetostrictive element 8 and a giant magnetostrictive element 8
It is formed in a substantially rectangular frame shape by two members of a substantially one-letter upper frame 10B abutting on the tip side of the frame. Then, the upper frame 10 is attached to the pins 11, 11 formed at the tip of the lower frame 10A.
B is engaged so as to be slidable in the direction of expansion and contraction of the giant magnetostrictive element 8. Thereby, when the giant magnetostrictive element 8 is extended, the upper frame 10B slides in the extending direction.
The yoke 10 is not deformed, and the elongation of the giant magnetostrictive element 8 is not limited.

Further, since the yoke 10 is disposed so as to be rotatable around the giant magnetostrictive element 8, as shown in FIG.
Is arranged at a predetermined angle with respect to the frame 5,
The device can be mounted on a device that does not have a high overall height and therefore does not have enough space for installation in the height direction.

When the sectional area of the giant magnetostrictive element 8 is Sm, its saturation magnetic flux density is Bm, the saturation magnetic flux density of the material forming the yoke 10 is By, and its sectional area is Sy,
If the magnetic flux formed in the giant magnetostrictive element 8 and the yoke 10 is in a saturated state, then Bm · Sm = By · Sy holds.

For example, as the giant magnetostrictive element 8,
When the yoke 10 is molded with 45 permalloy using ETREMATERENOL-D (trade name of Etrimer) of mm ² , Sm = 25 × 10 ⁻⁶ [m ² ], Bm = 0.9
[T], By = 1.4 [T]. Therefore, in order to form a magnetic flux in the giant magnetostrictive element 8 with a saturation magnetic flux density, it is sufficient that the cross-sectional area Sy of the yoke 10 is about 17 × 10 ⁻⁶ [m ² ]. Here, the yoke 10 is formed in a rectangular frame shape, and two closed magnetic circuits are formed outside the coil 7. Therefore, the sectional area of each member constituting the yoke 10 is in contact with the giant magnetostrictive element 8. 8.5 x 10
^-6 [m ² ] is sufficient.

Reference numeral 12 denotes a spring that urges the fingers 2R and 2L in the closing direction, 13 denotes a clamp pressure adjusting screw that adjusts the clamp pressure of the fingers 2R and 2L by adjusting the strength of the spring 12, and 14 denotes an ultra-high pressure screw. A prestress adjusting screw for applying a prestress to the magnetostrictive element 8.

The above is an example of the configuration of the present invention, and its operation will be described below. First, the clamp pressure adjusting screw 13
And the prestress adjusting screw 14 is adjusted. More specifically, a bias current is supplied to the coil 7 to apply a magnetic bias, and the pad 4R,
The screws 13 and 14 are adjusted so that the distance between the 4Ls is about 100 μm, and a negative current for canceling the bias current is supplied or the pads 4R and 14R are turned off when the bias current is turned off.
The screws 13 and 14 are adjusted so that 4L is in close contact and a force of about 50 gf is obtained.

[0031] Here, the magnetic field when passing a positive current is formed in the coil 7, and super-magnetostrictive element 8 is extended by its magnetic force, finger 2R, since the force point P ₁ of the rear end of 2L is pressurized,
The fingers 2R and 2L are connected to the fulcrum P connected to the frame 5.
Rotate outward around ₃ and open. At this time, since the giant magnetostrictive element 8 and the yoke 10 form a closed magnetic circuit through which the magnetic flux generated by the coil 7 passes, the total magnetic resistance is reduced, and at the same time, the leakage magnetic flux is reduced, and the magnetic flux is efficiently reduced. It can act on the giant magnetostrictive element 8. Here, if the yoke 10 is formed of a material having a high magnetic permeability, the magnetic resistance is further reduced. Therefore, the performance required for the manipulator head 1 can be obtained with a much smaller magnetomotive force than in the past, and the voltage / current supplied to the coil 7 can be reduced by that much, and in this example, about +2 V / + 0.25 A there were.

[0032] Then, a positive current is turned off, the magnetic field in the reverse direction flows negative current is formed in the coil 7, by the magnetic force, finger 2R, super-magnetostrictive element which has pressed the force point P ₁ of the rear end of the 2L since 8 contracts, finger 2R by the resilience of the spring 12, 2L close pivoted inward about the fulcrum P ₃ which is connected to the frame 5. Also in this case, since the closed magnetic circuit is formed by the giant magnetostrictive element 8 and the yoke 10, the magnetic flux can be efficiently applied to the giant magnetostrictive element 8, and the negative voltage / current supplied to the coil 7 is About -2V / -0.25A is enough.

Then, under the same conditions as described above, a wire diameter of 0.25 mm
Current of ± 0.25 A at a frequency of 10 Hz (opening time 0.09
Seconds and a closing time of 0.01 seconds).
Even after the lapse of 00 hours (1 × 10 ⁸ times of driving), the initial clamping performance was maintained, and the relative temperature increase of the surface of the coil 7 was 5 ° C. or less.

Accordingly, heat generation of the coil 7 and thermal expansion of the giant magnetostrictive element 8 due to the heat hardly occur, and there is no change in performance even when used for a long time, so that the reliability of the wire bonding machine incorporating this wire clamper is improved. The product yield is improved, and the efficiency of the bonding operation can be increased.

As described above, the means for applying a magnetic bias to the giant magnetostrictive element 8 is not limited to the case where a bias current is supplied to the coil 7 but may be applied to a magnetic circuit (for example, at two places where the giant magnetostrictive element 8 and the yoke 10 are in contact with each other). Alternatively, a permanent magnet having a large surface magnetic flux density, such as a samarium-cobalt magnet, may be provided on the yoke 10).

Also, the case where the manipulator head 1 according to the present invention is used as a wire clamper of a wire bonding machine has been described, but the present invention is not limited to this, and the manipulator head as a manipulator head for gripping a minute object of several μm to several hundred μm is described. , Machine tools, medical machines, micromachines and the like.

[0037]

As described above, according to the present invention, since the closed magnetic circuit is formed by the giant magnetostrictive element and the yoke, the magnetic reluctance of the magnetic field generated by the coil is reduced, which is necessary for the manipulator head. Performance can be obtained with a much smaller magnetomotive force than before, and not only can the amount of current flowing through the coil be reduced to reduce the amount of heat generated, but also the performance due to the thermal expansion of the giant magnetostrictive element caused by this. It has a very good effect of not causing a change. Further, when a material having a high magnetic permeability is used for the yoke, the magnetic resistance is further reduced, so that the amount of current flowing through the coil can be further reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manipulator head according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view showing a giant magnetostrictive actuator.

FIG. 4 is an explanatory view showing a wire bonding machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Manipulator head 2R, 2L ... Finger 3 ... Giant magnetostrictive actuator 4R, 4L ... Pad 5 ... Frame 6 ... Radiation fin 7 ... Coil 8 ... Giant magnetostrictive element 10 ... Yoke

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takaaki Makino 1-3-3 Azaminominami, Aoba-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Moritex Yokohama Technical Center 3F060 GA00 GB11 HA00 3F061 AA01 BA03 BB03 BC09 BD00 DB00 5F044 BB15

Claims (6)

[Claims] A giant magnetostrictive actuator that expands and contracts a bar-shaped giant magnetostrictive element (8) in the axial direction with a magnetic field generated by a coil (7) and that opens and closes a pair of fingers (2R, 2L) using the elastic deformation. In the manipulator head provided with 3), the giant magnetostrictive actuator (3) includes the giant magnetostrictive element (8) arranged at the center of the coil (7) and the yoke (10) arranged outside the coil (7). And a closed magnetic circuit for passing a magnetic flux generated by the coil (7). 2. A frame (5) on which said giant magnetostrictive actuator (3) is mounted is integrally attached to a rear end side of said fingers (2R, 2L), and said frame (5).
2. The manipulator head according to claim 1, wherein the manipulator head is formed to have a T-shaped cross section having radiation fins protruding outward. 3. The giant magnetostrictive element (8), wherein the yoke (10) is provided.
The manipulator head according to claim 1, wherein the manipulator head is formed in a substantially rectangular frame shape rotatable around the center. 4. The yoke (10) is made of 45 permalloy, 50
4. A high magnetic permeability material such as permalloy, 78 permalloy, pure iron, silicon class, soft magnetic amorphous, directional silicon class, alpalm, sendust, superalloy with Mo, supermalloy with Cu, etc. Manipulator head. 5. The yoke (10) is composed of at least two members (10A, 10B), one of which (10A) extends with respect to the other (10B) in the direction of expansion and contraction of the giant magnetostrictive element (8). 5. The manipulator head according to claim 1, which is slidably formed. 6. A giant magnetostrictive actuator which expands and contracts a bar-shaped giant magnetostrictive element (8) in the axial direction by a magnetic field generated by a coil (7), and opens and closes a pair of fingers (2R, 2L) using the elastic deformation. In the manipulator head provided with 3), a frame (5) on which the giant magnetostrictive actuator (3) is mounted is integrally attached to a rear end side of the fingers (2R, 2L), and the frame (5) is mounted on an outer side. Cross section T having a radiation fin (6) projecting toward
A manipulator head formed in a character shape.