JPS5969940A - Wire bonding device - Google Patents

Abstract

PURPOSE:To control the vertical operation of a capillary with high accuracy at high speed, and to improve productivity and yield by detecting the direction of rocking and quantity of rocking of a tool lifter arm and controlling the arm on the basis of the detecting values. CONSTITUTION:A reflecting mirror 16 is composed of irregular sections 16a, 16b of width P and stepped difference D, and is fixed to the side surface section 2e of the tool lifter arm 2. Laser beams 11a, 17a from the laser oscillators of irradiation light-receiving optical systems 6b, 6c are reflected to the reflecting mirror 16, and the reflected lights 11b, 17b generate an interference and the interference is detected by a photodetector as the intensity of beams. A photoelectric conversion output has the phase difference of 90 deg. because a space lbetween the laser beams 11a, 17a is 2PXn+1/8X2P (n=1, 2...). The direction of rocking of the arm 2 is obtained from the relationship of phase in a signal processing section 30, and the quantity of rocking is acquired by calculating the number of the waves of the signal. A bonding control circuit 8 compares a signal from the processing section 30 with an ideal rocking information and outputs a control signal, and the rocking operation of the arm 2 is controlled.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in wire bonding equipment.

[Technical background of the invention and its problems]

In general, a wire-dending device used for assembling integrated circuits, etc. pushes a capillary into which a wire has been inserted into a pad of a pellet, which is the first bonding point, and then dends the capillary in the vertical and x-y force directions. Let me move it.

The wire is connected by repeatedly feeding out the wire, bonding it to the lead part of the lead frame that is the second bonding point, and then raising the capillary and cutting the wire. .

By the way, in the above bonding operation, the bonding load when the capillary presses the bonding surface is particularly important in determining the quality of the bonding. It is still necessary to move the capillary up and down as fast as possible to increase productivity.

Therefore, conventionally, for example, a shaft encoder is attached to the rotating shaft of the sole lifter arm for supporting the capillary and driving it in one swing, and this encoder detects the rotation angle of the tool lifter arm, and based on this detected value. controls the vertical movement of the capillary.

However, shaft encoders generally have two fixed slits with different slit arrangements facing a movable slit that rotates together with the tool lifter arm.
41, and the rotating state of the tool lifter arm is detected by receiving the output light from the light source passing through the movable slit and the fixed slit with a light receiver for each fixed slit.

Therefore, the resolution of the shaft encoder is determined by the slit pitch of the moving slit and the fixed slit, and the pitch of this slit is generally 8μ.
Since the capillary can only be finely divided to the order of m, its resolution is limited and it is extremely difficult to properly monitor the vertical movement of the capillary.

On the other hand, another method for monitoring the vertical movement of the capillary is to convert the swing rotation angle of the tool lifter arm into a linear displacement via a link, and detect this with a linear encoder. However, in such a configuration,
Since the link mechanism is complicated and large, the overall size of the device increases, and the driving load on the tool lifter arm increases, resulting in high-speed operation.

[Purpose of the invention]

The present invention enables the swinging state of a tool lifter arm to be detected with high precision and in a non-contact manner, thereby enabling the vertical movement of a capillary to be controlled accurately and at high speed, thereby providing a wire bonding device with high productivity and yield. The purpose is to

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a tool lifter arm with a reflecting mirror whose surface is continuously formed with uneven portions of a predetermined width, and directs two coherent beams of light onto the surface of the reflecting mirror. The reflected light of the =T interference beam light, which is irradiated with a mutual interval and interferes with the uneven portion, is received by a photodetector, and the phase relationship between the received light outputs and the wave number of the signal are determined. , the direction and amount of swing of the sole lifter arm are detected, and the vertical movement of the capillary is controlled based on the detected values.

[Embodiments of the invention]

1 and 2 show the structure of a wire bonding apparatus according to an embodiment of the present invention, FIG. 1 being a plan view thereof, and FIG. 2 being an id1 plane view.

1 in the figure is the base, and this -Ji
A sole lifter arm 2 is pivotally attached to the support column 1a of the lj stand 1 so as to be rotatable in the direction of arrow O. A bonding portion 4 is provided on the front side of the tool lifter arm 2 and supported by a plate h3. This bonding part 4b is a tool arm 4b having a capillary 4a attached to its tip, supported by a holder 4c, and a holder 4C.
An actuating portion 4d is provided in a protruding manner at the upper portion of the actuator.

A tension spring 2c is connected between this actuating part 4d and the fixing part 2b protruding from the i of the sole lifter arm 2 (the 5-way extending part 2a).
is installed, and a steady state of the binding portion 4 is set by the tension spring 2 (! toss) collar 4e. On the other hand, a moving coil 5a is attached to the lower surface of the rear side extending portion 2d of the tool lifter arm 2. The moving coil 5a, together with a yoke 5b installed on the base 1, operates as a motor 5 for swinging the tool lifter arm 2 about the pivot point. Note that 5c is a magnet.

Now, on the base 1 of the bondinder mechanism as described above, an optical system 6 of a movement state detection device for detecting the swing state of the tool lifter arm 2 is installed opposite the side surface 2e of the tool lifter arm 2. It is installed. This optical system 6 has two sets of irradiation and light receiving optical systems 6b and 6c, each equipped with a laser oscillator, installed on a support column 6a.

In addition, a reflector 16 is provided on the side surface of the tool lifter arm 2.
is attached.

In addition, in the figure, 30 is a signal processing unit that processes the light reception signal obtained from the optical system 6 and emits a focus adjustment signal to the optical system 6, which together with the optical system 6 constitutes a movement state detection device. .

Further, 7 is a motor drive circuit for issuing a drive signal to the motor 5 to swing the tool lifter arm 2, and 8 is a bonding control circuit for controlling the entire bonding operation.

By the way, the movement state detection device is configured as follows. FIG. 3 is a schematic 4-4 diagram of the same device. In addition, in the figure, there are two sets of irradiation and light reception optical systems 6b and 6c.
The other one is omitted because it has the same configuration.

In this detection centering, first, a detection laser beam 11a generated by a laser oscillator 1o is made into a parallel beam by a collimating lens 12, and this parallel laser beam lla is guided to a wavelength plate 14 via a beam splitter 13. After the phase is rotated by 90° at step 14, the beam is focused by an objective lens 15 which is movable in the optical axis direction (direction of arrow Y) by a moving coil 18, and is irradiated onto the surface of a reflecting mirror 16.

As shown in FIG. 4, this reflecting mirror 16 has parallel concave and convex portions 16a and 16b each having a width P and having steps, on its surface.
is continuously formed and fixed to the side surface 2e of the sole lifter arm 2. As the tool lifter arm 2 swings, it moves in the direction in which the concave and convex portions 16a and 16b are arranged (arrow x direction).

Note that 11a and 17a in the figure indicate detection laser beams that are irradiated onto the surface of the reflecting mirror 16, respectively, and the distance t between the uneven portions 16a and 16b in the arrangement direction is
is defined as L=2PXn+±・2P [μm] 8 □----. However, n ”= 1 + 21.3
It is H... In addition, the detection device rotates the phase of the laser beam llb reflected by the different surface of the reflecting mirror 16 by 90 degrees by the wave plate 14 via the objective lens 15, and then rotates the phase of the laser beam llb reflected by the different surface of the reflecting mirror 16 by the beam splitter 1.
3 is reflected and separated and passed through a cylindrical lens 19 to a photodetector 20.
The photodetector 20 conducts photoelectric conversion and introduces the signal into the signal processing section 30. Here, the photodetector 20 is
As shown in FIG. 5, there are four photodetectors 20a.

20b, 20c, and 20d are arranged adjacent to each other.

On the other hand, as shown in FIG. 5, the signal processing section 30 adds the photoelectric conversion outputs of the photodetecting sections 20a to 20d of the photodetector 20 to each other in an adding circuit 31, and outputs the added output TSI.
is led to the movement information detection circuit 32. This movement information detection circuit 32 outputs the addition output TSI corresponding to the laser beam 11a as well as another laser beam 17.
The addition output TS2 corresponding to a- is input. Then, the mutual phase relationship between these summation outputs TSI, TS2, and which one is leading is detected by phase comparison, and the above-mentioned summation outputs TSI, TS2 are detected by a counter.
The wave number of 2 is multiplied by 51, and the detection result from the phase comparison is output as information representing the moving direction of the object, and the counting result of the counter is output as information representing the amount of movement of the object.

In vain, the signal processing section 30 includes each light detection section 20a.

~, 20cl of light 'llt, among the converted outputs, the outputs of the photodetectors 20a and 20d and the photodetector 'i'H (S 20b and 20c are added by adders 33 and 34, respectively, and the respective addition outputs are The differential output is obtained by the differential amplifier 35 and applied to the moving coil and drive circuit se.The moving coil stage drive circuit 36 receives a signal E=(as+ds)-(bs+cs). However, as+l)S+08+ds are photodetectors 20a, 2θb, and 20c, respectively.

This is the photoelectric conversion output of 20d.

The moving coil drive circuit 36 includes the differential amplifier 35
A drive signal is generated for the difference output E to drive the moving coil 18). ll objective lens 15
is moved in the optical axis direction to adjust the focal position of the laser beam lla.

Next, the operation of the device configured as above will be explained.

First, when the bonding control circuit 8 issues a motor drive control signal corresponding to a predetermined tool curve, the motor drive circuit 7 operates and a drive current is supplied to the motor 5. As a result, the motor 5 operates and the tool The lifter arm 2 swings. Therefore, the capillary 4Ia moves up and down in the direction of arrow C, thereby performing bonding.

The moving state detection device l=7 detects as follows.

That is, the laser beam 11a generated from the laser oscillator 1o is focused to a predetermined spot diameter by the objective lens 15, and is irradiated onto the convex-concave portion forming surface of the reflecting mirror 16, where it is reflected. At this time, the soil reflected light is reflected from the convex portion 16a.
Interference occurs between the light path lengths and the concave fits 16b, and the magnitude of this interference is expressed as the strength of the light d, which is detected by the photodetector 20. Note that the other radar beam 17a is also irradiated onto the surface of the reflecting mirror 16 in the same manner as the upper beam 11a, and is reflected as interference light and detected by a photodetector.

Therefore, when the reflecting mirror 16 moves with the rocking of the tool lifter arm 2, each reflected laser beam 1 l
Since the amount of interference of F7.b, 17b changes accordingly, the photodetector 2o detects triangular wave-shaped light F7.b as shown in FIG. 6, for example. The converted outputs TSI and TS2 are obtained. These photoelectric conversion outputs TSI and TS2 have a phase difference of 90° since the interval t is 7=2PXn+±X 2'P as described above.

The photoelectric conversion output TS1. thus obtained. The TS2 are mutually added by the addition circuit 31 of the signal processing section 30 and guided to the movement information detection circuit 32, and the swinging direction of the tool lifter arm 2 is determined from the phase relationship described above, and the wave number of the triangular wave signal is determined. By counting, the amount of rocking (rotation angle) can be determined. Information indicating the rocking direction and the rocking amount thus determined is led to the bonding control circuit 8. As a result, the bonding control circuit 8 compares each of the above rocking information with, for example, preset ideal rocking information to determine the difference, and outputs a control signal created to bring this difference closer to zero. to control the swinging motion of the sole lifter arm 2. Therefore, the tool lifter arm 2 operates in a state close to the ideal rocking motion, and as a result, the cabin I74
A allows bonding to be performed with an optimal load and enables high-speed vertical movement.

On the other hand, each of the reflected laser beams 1 l b , 17 b
is focused by the cylindrical lens 19 and received by the photodetector 20, so if the laser beam 11a.

If the focus of the beam 17a is shifted, the light will not be received in a perfect circle as shown in FIG. 7(a), but will be received in a diagonally elongated state as shown in FIG. 7(b). When such light is received, each photodetector 20a to 20d
The difference in received light intensity in the diagonal direction is detected by adders 33 and 34 and a differential amplifier 35. Then, a signal corresponding to the difference output is outputted from the moving coil and drive circuit 36, and as a result, the moving coil 18 (by which the objective lens 15 is controlled to move) and the laser beams 11a, 17b are
The focus is adjusted so that the shift in the focus position of the image becomes zero. Note that 8th C] shows the relationship between the differential output E of the differential amplifier 35 and the focal position. Therefore, by this automatic adjustment of the focal position, the movement information can be detected under extremely stable conditions.

As described above, in the apparatus of this embodiment, the reflecting mirror 16 having a concave and convex portion with a predetermined width formed on its surface is attached to the tool lifter arm 2, and the surface of the reflecting mirror 16 is irradiated with two laser beams. Since the reflected interference light is received and the swinging state of the tool lifter arm 2 is detected from the received light output, the swinging state of the tool lifter arm 2 is simpler and more accurate than when using a conventional slit-based encoder. state can be detected. However, since the operating state can be detected without contacting the tool lifter arm, unlike the case of detecting the motion via a conventional link mechanism, the load on the tool lifter arm 2 can be reduced. As a result, the capillary 4a can be controlled with high precision. Since it is possible to set the lllllll pounding to the optimum value and reduce the driving load of the tool lifter arm 2, the cab 2IJ
4A high-speed operation is possible, and therefore the yield and productivity of sanding can be improved. However, in this embodiment, the focal position of the objective lens 15 is adjusted to detect the distortion of the reflected laser beam and make it zero, so it is possible to always keep the deviation of the focal position to a low value. As a result, detection accuracy can be further improved. Therefore, the accuracy of controlling the vertical movement of the cabin IJ 4 a can be further improved.

It should be noted that the present invention is based on the above embodiments. For example, a reflecting mirror with continuous unevenness formed in the circumferential direction is attached to the rotating shaft of the tool lifter arm 20, and two laser beams are irradiated to the unevenness forming surface of this reflecting mirror. By receiving the reflected interference light, the rotation direction and rotation angle of the tool lifter arm 2 may be respectively detected. Further, in the above embodiment, two laser oscillators were provided to generate each laser beam, but the output laser beam of one laser oscillator may be divided into two systems to obtain two laser beams. .

Furthermore, in order to prevent the surface of the reflecting mirror from being damaged, a transparent film is coated or a substrate is made of transparent acrylic resin, and irregularities are formed on this by vapor deposition of aluminum. The laser beam may be irradiated from the non-forming surface side. In addition, the installation position of the reflecting mirror, the dimensions of the structure, the configuration of the signal processing section, etc. may be modified by 4:+ij without departing from the gist of the present invention.
I can do it.

〔Effect of the invention〕

As described in detail above, the present invention provides a sole lifter arm with a reflecting mirror that continuously forms irregularities of a predetermined width on its surface, and directs two coherent beams onto the surface of the reflecting mirror in a predetermined manner. The reflected light of the coherent beam light, which is irradiated with a mutual interval and interferes with the uneven portion, is received by a photodetector, and from the mutual phase relationship of the received light outputs and the wave number of the signal, the tool The direction and amount of swing of the lifter arm are detected, and the vertical movement of the capillary is controlled based on the detected values.

Therefore, according to the present invention, the swinging state of the tool lifter arm can be detected with high precision and in a non-contact manner, and the vertical movement of the capillary can be controlled with high precision and at high speed u'2, thereby improving the production quality. Also, it is possible to provide a wire bonding apparatus H with a high yield.

[Brief explanation of the drawing]

Figures 1 and 2 show wire bonding 'Af?' in one embodiment of the present invention. : indicates +11゛I formation of i,
1 is a plan view thereof, FIG. 2 is a side view, FIG. 3 is a schematic diagram of the moving state detection device, and FIGS. 4 and 5 are diagrams of the main parts of the interior H'v. , Figures 6 to 8 are 3rd Wi
Figure 6 is a signal waveform diagram of the photoelectric conversion output, and Figure 7 (a
), (b) is a schematic diagram showing the state of reception of reflected interference light on the photodetector, and Figure 8 shows the signal for focus adjustment and the focal position 1.
It is a characteristic diagram which shows the relationship with 183 degrees. 1°, ° base, 2... sole lifter arm, 4a...
- Capillary, 4b... Tool arm, 5... Motor, 6... Optical system, 10... Laser oscillator, Ila. 17a = laser beam, 1 lb, "17b.
...Reflected interference light, 12...Collimating lens, 13.
... Beam splitter, 14... Wave plate, 15... Objective lens, 16... Reflector, 16a, 16b... Concave and convex portion, 18... Moving coil, 19... Cylindrical lens, 20... ...Photodetector, 20a+~, 20d...
Photodetection section, 30... signal processing section. Applicant's representative Patent attorney Takehiko Suzue Figure 3 16 Figure 4 Figure 5 1] 2 Figure 6 165 Figure 7 (a) (b) Figure 8

Claims (1)

[Claims] In a wire ending device that supports a tool lifter arm on a tool lifter arm and swings the tool lifter arm, the above-mentioned ending capillary is moved up and down, thereby performing tending. A reflecting mirror is provided integrally with the tool lifter arm so that the uneven portions are not formed continuously, and the forming direction of these uneven portions coincides with the swinging direction of the tool lifter arm, and the uneven portion of this reflecting mirror is provided. an irradiation optical system that irradiates the formation surface with two coherent beams of light having a predetermined mutual interval;
a light-receiving optical system that separately receives interference light reflected by the reflector of each of the coherent beams with a photodetector; A movement information detection circuit detects the swinging direction and amount of the arm, and the swinging operation of the tool lifter arm is controlled according to the information on the swinging direction and amount detected by this movement information detection circuit. 1. A wire ending device comprising a ending control circuit for causing a capillary to perform a desired operation.