JPH04279039A - Wire-bonding method and device - Google Patents

Abstract

PURPOSE:To enable a process time to be reduced and prevent bonding failure. CONSTITUTION:A rotary axis 13 is rotated by a step motor 31, thus enabling a torch electrode 25 to be stopped at a waiting position A and a discharge position B. Discharging is performed between a tip portion 29 of a metal thin wire 28 and a discharge portion 26 of a torch electrode 25 at the discharge position B for forming the tip portion 29 in spherical shape and then the torch electrode 25 is moved to the waiting position A and then a capillary tool 27 is lowered, thus enabling the tip portion 29 to be crimped against an object to be crimped which is not illustrated. Therefore, the torch electrode 25 can be moved at high speed and so that it does not generate shock.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method and apparatus for connecting, for example, a surface electrode of a semiconductor chip and an external lead electrode using a thin metal wire.

0002

2 and 3 show a conventional wire bonding apparatus, with FIG. 2 being a perspective view and FIG. 3 being a side view seen from the right side of FIG. In these figures, 11 is a main body, 12 is a rolling bearing fitted into the main body 11, and 1 is a rolling bearing fitted into the main body 11.
Reference numeral 3 denotes a round rod-shaped rotation shaft rotatably supported by two rolling bearings 12. 14 is a lever fixed to the front end of the rotation shaft 13, 15 is a left stopper, and 16 is a right stopper. The left stopper 15 and the right stopper 16 regulate the rotation angle position of the lever 14. 17 is lever 1
The lever 14 is compressed and inserted between the support plate 18 and the lever 14.
It is a coil spring that presses counterclockwise. 19 is a mounting plate provided on the main body 11, 20 is a push-pull solenoid, and the solenoid main body 21 is fixed to the mounting plate 19.
and a plunger 22 connected to the upper part of the lever 14.

Reference numeral 23 indicates an L-shaped support fitting fixed to the left end of the rotating shaft 13, and 24 indicates an L-shaped support fitting fixed to the support fitting 23.
A torch electrode 26 is insulated from the supporting metal fitting 23 by the insulating plate 24 and rotatably supported on the rotating shaft 13 in the form of a cantilever arm via the insulating plate 24 and the supporting metal fitting 23. is a discharge part of the torch electrode 25, and a discharge is caused between it and the tip part 29 of a thin metal wire 28, which will be described next. 27
is a capillary tool that is driven in the vertical direction by a vertical drive device (not shown) and moves linearly within a predetermined movement range on a movement line ML, and has a through hole (not shown) inside it.
A thin metal wire 28 is inserted into it, with a tip 29 slightly protruding.

Next, the operation will be explained. When the device is in a standby state, the thin metal wire 28 has its tip 29 protruding from the capillary tool 27 and is held by a gripping means (not shown), and the push-pull solenoid 20 is not energized, so the lever 14 is held by the coil spring 17. The discharge portion 26 of the torch electrode 25 supported by the rotation shaft 13 is at the position shown by the dashed line in FIG.
The capillary tool 27 is located at A (hereinafter referred to as the standby position).
The capillary tool 27 is in a state where it is retracted outside the movement range and does not interfere with the movement of the capillary tool 27.

When the push-pull solenoid 20 is energized, the plunger 22 is attracted and the lever 14 is activated by the coil spring 17.
It rotates clockwise against the pressing force of , and its lower part collides with the left stopper 15 and stops. At this time, the discharge part 26 of the torch electrode 25 supported by the rotation shaft 13 rotates from the standby position A in the direction of arrow R and stops at a predetermined position (hereinafter referred to as the discharge position) B within the movement range of the capillary tool 27. do.

[0006] Thereafter, an electrical discharge is generated between the tip 29 of the thin metal wire 28 and the discharge portion 26 by a power supply device (not shown), thereby forming the tip 29 into a spherical shape. Next, the push-pull solenoid 20 is de-energized, the lever 14 is pressed by the spring force of the coil spring 17, the rotation shaft 13 is rotated counterclockwise, the discharge part 26 is returned to the standby position A, and the tip part 29 is connected to the capillary. The tool 27 pushes down the moving line ML to press the object to a predetermined electrode (not shown). Next, the object to be crimped is moved a predetermined distance so that the next electrode to be connected is directly below the capillary tool 27 (on the moving line ML), and the capillary tool 27 is lowered again to connect the thin metal wire 28. The capillary tool 27 and the clamper device are lifted to tear the thin metal wire 28 by pinching the thin metal wire 28 using a clamper device (not shown) as a gripping means, and the capillary tool 27 is returned to a predetermined position above. finish.

[0007]

[Problems to be Solved by the Invention] Since the conventional wire bonding apparatus is constructed as described above and wire bonding is performed by the method described above, it is necessary to move the discharge portion 26 of the torch electrode 25 to the discharge position B. Since the lever 14 is moved and stopped by colliding with the left stopper 15, an impact is generated and the discharge portion 26 of the torch electrode 25 vibrates. Therefore, it is necessary to wait until the vibration of the discharge section 26 subsides before starting the process of generating the next discharge, resulting in a problem that the process time becomes longer. In addition, the above-mentioned impact may deform the thin metal wire 28 held by the gripping means (not shown). Therefore, in the process of forming the tip 29 of the thin metal wire 28 into a spherical shape by electric discharge, variations in the spherical diameter, Alternatively, there are problems such as discharge errors and wire bonding defects.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a wire bonding method and apparatus that can shorten the process time and prevent defects in wire bonding.

[0009]

[Means for Solving the Problems] A wire bonding method according to the present invention includes: (1) rotating a rotating shaft supporting a torch electrode by a rotational drive means to connect a torch electrode to a capillary through which a thin metal wire is inserted; The process of moving the tool to a predetermined position within the movement range, (2) the process of causing an electric discharge between the torch electrode and the tip of the thin metal wire to make the tip spherical, and (3) rotating the rotation axis. The torch electrode is moved out of the moving range of the capillary tool.

Further, the wire bonding apparatus according to the present invention is driven by a rotary drive means that supports and rotates the torch electrode, and moves the torch electrode to a predetermined position outside the movement range of the capillary tool and to a predetermined position within the movement range of the capillary tool. It is equipped with a rotating shaft that allows it to stop at any time.

[0011]

[Operation] In the wire bonding method of the present invention, the torch electrode is moved into and out of the movement range of the capillary tool by the rotation of the rotation shaft driven by the rotation drive means, so no impact is generated. It is possible to operate quickly. In particular, when the torch electrode is moved to a predetermined position within the movement range, since the torch electrode does not vibrate, discharge can immediately begin between the torch electrode and the tip of the thin metal wire in the next process, which reduces the overall process time. In addition, since the thin metal wire gripped is not deformed by impact, defective bonding can be prevented.

Further, in the wire bonding apparatus according to the present invention, the rotating shaft is rotated by the rotating rotation drive means and stopped at a predetermined position within the movement range of the capillary tool and at a predetermined position outside the movement range. Therefore, no impact is generated when the device is stopped, and the gripping means that grips the thin metal wire is not subjected to impact, so there is no risk of deforming the thin metal wire, and the operation can be performed at high speed.

[0013]

[Embodiment] FIG. 1 is a perspective view of a wire bonding apparatus showing an embodiment of the present invention. In the figure, reference numeral 31 denotes a step motor which is directly connected to the rotation shaft 13 and is rotation driving means for driving the rotation shaft 13. , 32 is a light-shielding disc attached to the rotating shaft 13, and two notches 33 and 34 are provided at predetermined positions on its outer periphery. 35 is the rotation axis 13
is an insulating bushing fitted to the other shaft end of the
A torch electrode 25 is fixed in the form of a cantilever arm as shown in the figure. Note that the arms of the torch electrode 25 are made of thin-walled pipes to reduce inertia, and the upper surface of the discharge part 26 of the torch electrode 25, that is, the part where discharge occurs between the tip 29 of the thin metal wire 28, is not damaged during discharge. A thin plate 36 made of platinum is attached to reduce this. 37 is a photosensor attached to the main body 11, and the notch 33 of the light-shielding disc 32,
The position of 34 is optically detected.

Next, the operation will be explained. Torch electrode 2
In the standby state, the capillary tool 5 is retracted to a standby position A outside the movement range of the capillary tool 27, similar to the conventional example shown in FIG. At this time, the rotation shaft 13 is at a predetermined first angular position. A predetermined number of pulses are given to the step motor 31 to rotate it by a predetermined angle, and the rotation shaft 13 is rotated to the second angular position, thereby moving the discharge portion 26 of the torch electrode 25 to the discharge position B within the movement range of the capillary tool 27. Move to. At this time, the light shielding disc 3
Since the notch 34 of No. 2 comes to the detection position of the photosensor 37, the position can be confirmed. Subsequently, electric power is supplied from a power source (not shown) between the tip 29 of the thin metal wire 28 and the thin plate 36 of the discharge section 26 to cause discharge, thereby shaping the tip 29 into a spherical shape. When the shaping of the tip 29 into a spherical shape is completed, a predetermined number of pulses are given to the step motor 31 so that it rotates in the opposite direction to the previous one, and the rotation shaft 13 is rotated to the original first angular position, thereby removing the torch electrode. 25 is returned to the standby position A. At this time, the photo sensor 37 detects the notch 33 of the light-shielding disk 32 to confirm that the torch electrode 25 has returned to the standby position A. Other operations are similar to those of the conventional device shown in FIG.

The normal operation of the torch electrode 25 is as described above, but it can be stopped at any position by controlling the number of pulses applied to the step motor 31. capillary tool 2
7, the discharge portion 26 can be retracted largely as needed to improve workability.

Furthermore, since a platinum thin plate 36 is attached to the discharge portion 26 of the torch electrode 25, the discharge life is greatly improved. Of course, the thin plate 36 may be plated with platinum, the thin plate 36 may be made of an arc-resistant metal material other than platinum, or the entire discharge section 20 may be made of an arc-resistant material. Further, when controlling the rotation angle position of the rotation shaft 13 using the step motor 31, the light shielding disk 32 and the photosensor 37 are not essential, but are provided as a backup for position detection. Note that, in place of the step motor 31, a similar effect can be obtained by combining a rotating drive means such as a DC motor, an induction motor, or a hydraulic motor with the light-shielding disk 32 and the photosensor 37.

[0017]

As described above, according to the present invention, there is provided a wire bonding method and apparatus that can shorten the process time and prevent bonding defects since the rotating shaft supporting the torch electrode is rotated by the rotation drive means. can be provided.

[Brief explanation of the drawing]

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

FIG. 2 is a perspective view showing a conventional wire bonding device.

FIG. 3 is a side view of a conventional wire bonding apparatus viewed from the right side of FIG. 2;

[Explanation of symbols]

13 Rotation axis 25 Torch electrode 26 Discharge part 27 Capillary tool 28 Thin metal wire 29 Tip 31 Step motor A Standby position B Discharge position ML moving line

Claims (2)

[Claims] [Claim 1] A thin metal wire is held and inserted into a capillary tool that is movable in a predetermined movement range so that its tip protrudes, and a discharge is caused between a torch electrode and the tip. A wire bonding method in which the tip is formed into a spherical shape and crimped onto an object to be crimped, the wire bonding method comprising the following steps. (1) A step of moving the torch electrode into the movement range of the capillary tool by rotating a rotating shaft supporting the torch electrode by a rotating rotation drive means (2) The moved torch electrode and the capillary (3) A step of rotating the rotating shaft by the rotary drive means to retract the torch electrode out of the movement range of the capillary tool. 2. The torch is driven by a capillary tool which is movable within a predetermined movement range and into which the tip of a thin metal wire held by a gripping means is inserted, and a rotary drive means which supports and rotates the torch electrode. a rotating shaft configured to stop the electrode at a predetermined position outside the movement range and at a predetermined position within the movement range, and between the tip of the thin metal wire inserted into the capillary tool and the torch electrode; A wire bonding device equipped with a power supply device that generates a discharge.