JPH06268130A - Dam-bar working apparatus of semiconductor - Google Patents

Abstract

PURPOSE:To surely remove dam dars even when the pitch and the width of the dam bars are irregular and to remove the dam bars which are situated at equal distances from both start end parts and finish end parts of the dam bars by a method wherein a semiconductor device is moved back and forth, the semiconductor device is irradiated with a laser beam at its advance route and its return route and the dam bars are removed. CONSTITUTION:A semiconductor device is moved back and forth, dam bars 23 which couple a lead frame for the semiconductor device are irradiated with a laser beam from a working head in its advance route and its return route, and the dam bars 23 are removed. In addition, e.g. in the advance route, parts around positions (a) at a prescribed distance L from start end parts of the dam bars along the advance-route direction are irradiated with the laser beam, and the dam bars 23 are removed. In addition, in the return route, parts around positions (b) at the prescribed distance L from the start end parts of the dam bars 23 along the return-route direction are irradiated with the laser beam, and the dam bars 23 are removed. Thereby, even when the dam bars are wide, the dam bars can be removed in positions at the prescribed distance L from both end parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dam bar processing apparatus using a laser beam, which is suitable for removing a dam bar from a semiconductor device.

[0002]

2. Description of the Related Art A lead bar of a semiconductor device is provided with a dam bar in such a manner that the lead frames are connected to each other in order to prevent the resin from flowing over the lead frame after the resin molding. Then, after the resin molding, the dam bar is removed to make each lead frame electrically independent.
There are an example in which the lead frame is provided on two opposite sides of the four sides, and an example in which it is provided on all four sides.
The type provided on all four sides is QFP
It is called a shape and has a high number of frames.

The dam bar can be removed by a pressing method for removing the dam bars collectively for each side and a laser beam method for removing one dam bar one after another. Each has its own strengths and weaknesses,
Since the pitch between the lead frames is extremely narrow, the dam bar on the lead frame of the QFP type semiconductor device can be removed by a mechanical press method rather than the mechanical press method.
The removal method using a laser beam is excellent.

Japanese Patent Laid-Open No. 3-294077 discloses a conventional example of dam bar removal using a laser beam. This conventional example is an invention relating to a countermeasure against shrinkage distortion of a lead frame caused by the influence of resin during resin molding. Although the pitch of the lead frame should be in accordance with the standard set in advance, the lead frame shrinks during resin molding, and the pitch of the lead frame deviates from the standard value. Therefore, a reference hole is provided in the lead frame, the reference hole is optically monitored, and if there is a deviation, control is performed to change the irradiation position of the laser beam by the deviation.

An example of another conventional pulse laser processing machine is shown in FIG.
Shown in. A laser head 14, a processing head 12, a laser power supply 16, and a workpiece 10 that is a workpiece to be mounted and movable in a horizontal plane (in an XY plane). The XY table 11, the laser head 14, and the processing head 12 are vertically moved. A main controller 15 for automatically or manually controlling the movement of the Z table 13 and the XY table 11 that move in the (Z-axis direction) in the horizontal plane, the movement of the Z table 13 in the vertical direction, and the oscillation operation of the laser head 14 is performed. Prepare

The laser power source 16 is a laser controller 2
0, the stabilizing power supply 19, the capacitor unit 18, and the switch unit 17, the AC power supply supplied from the stabilizing power supply 19 is converted into DC according to the voltage value commanded from the laser controller 20, and is supplied to the capacitor unit 18. ,
The charge of the capacitor section 18 is supplied to the switch section 17. The switch unit 17 operates in accordance with a trigger signal instructing a pulse width and a pulse frequency from the laser controller 20, and accordingly, the pulse laser light is oscillated in a pulse shape from the laser head 14.

A beam shutter (not shown) is built in the laser head 14, and whether the pulse laser light is sent to the processing head 12 by opening or closing (O
N / OFF). That is, when the work 10 is processed (removing the dam bar), the beam shutter is opened, and when the work 10 is not processed, the beam shutter is closed. The operating time of this beam shutter is 100-300
It is about msec, and the control is performed from the laser controller 20 described above, but may be performed from the main controller 15 via the laser controller.

FIGS. 3A and 3B are explanatory views of a QFP type semiconductor device and dam bar processing. The QFP type refers to an IC package having a structure in which the lead frame 22 is led out from the four sides Q1 to Q4 of the semiconductor device 21 toward the outside.
Usually, two opposite sides of the four sides (for example, Q1 and Q)
Although the lead frame is derived from 3), in a high-density semiconductor device, since the number of lead frames also increases, the lead frame is formed on all four sides. Moreover, the pitch interval between the lead frames on each side is also extremely short. Dam bars 23 are formed on the lead frames 22 on each side so as to connect them. When the semiconductor device 21 is molded with resin, the dam bar 23 functions to prevent the resin from flowing out to the entire lead frame. The dam bar 23 is removed after the molding. The leadframe needs to be electrically independent. There are a mechanical removal method using a punch and a removal method using a laser for removing the dam bar 23. In FIG. 2, the removal method using a laser is adopted.

FIG. 3B is an enlarged view of the lead frame and the dam bar. After the removal of the dam bar including the point A is completed, the control sequence for removing the dam bar including the point B is as follows. (1) The table 11 is moved so that the laser irradiation position on the work 10 is changed from A to B. (2) When the position B is reached, the XY table 11 is stopped. (3) The beam shutter is opened. (4) Irradiate with a pulse laser. (5) Close the beam shutter. The above operations (1) to (5) are set as one sequence and repeated for each dam bar position, and dam bars are removed one after another. At this time, (1) to (5) are set to the main controller 1
By pre-programming the memory in 5, the sequence control becomes possible.

[0010]

[Patent Document 1] Japanese Patent Application Laid-Open No. 3-29407
No. 7 has a problem of shrinkage of the lead frame of the entire semiconductor device. Therefore, the positional fluctuation of the entire semiconductor device is monitored by the deviation of the reference hole. However, in addition to shrinkage due to resin molding, various positional deviations occur due to mounting errors on the processing table of the semiconductor device, pitch variations between lead frames during lead frame molding, and the like. In particular, in a QFP type semiconductor device for high-density framing, since the number of lead frames on one side is large and the pitch interval is narrow, it is not enough to monitor only the whole, and the positional deviation of each lead frame is taken into consideration. There must be. There are many examples of lead frame positional deviation due to fluctuations in the pitch width. That is, there is a problem that the pitch width is wide and narrow. Therefore, in order to correct the misalignment of the lead frame and remove only the dam bar, it is necessary to consider the method of processing in which the pitch width is wide and narrow as well as the correction of the individual positions of the lead frame.

Further, the conventional example shown in FIG. 2 has the following problems. The width of each dambar is 0.1 to 0.1
Since the thickness is about 0.3 mm and the thickness is around 0.15 mm, this cutting can be sufficiently performed by one pulse of pulsed laser light.
Therefore, the time required for actual processing corresponds to the time of the pulse width of the pulsed laser light, which is about 0.1 msec. However, in the processing steps (1) to (5) described above, the operating time of the beam shutter is 100 to 300 ms.
Depending on ec and the moving time of the table, it takes about 1 sec to cut one dam bar, and if the number of cut dam bars and the number of manufactured IC packages are taken into consideration, it takes too much processing time.

Generally, the pins are often arranged at the same pitch, but the pins are deformed due to manufacturing errors of the lead frame, distortion due to temperature history when molding with a resin, external force due to handling, etc. There is a case that the pitches are not necessarily equal when cutting. The above-mentioned dam bar cutting method is a method in which the locations where the dam bars are cut are registered in the main controller 15 in advance as a program. However, this method cannot deal with the fact that the above-mentioned pins are not arranged at an equal pitch, and further manufacture In the worst case where errors and deformations accumulate and the errors increase, there is a possibility that the pin portion of the lead frame that should be left may be damaged.

An object of the present invention is to provide a semiconductor device which enables the dam bar to be reliably removed even if the pitch and width of the dam bar are not uniform and equidistant from both the start end and the end end of the dam bar. The present invention provides a dam bar processing device.

[0014]

SUMMARY OF THE INVENTION According to the present invention, a semiconductor device is reciprocally moved, and a dam bar for connecting a lead frame of the semiconductor device is irradiated with a laser beam from a processing head in each of the forward path and the backward path of the semiconductor device. Are removed (claim 1).

Further, according to the present invention, a semiconductor device is reciprocated,
In each of the forward path and the return path, the dam bar connecting the lead frame of the semiconductor device is irradiated with the laser beam from the processing head to remove the dam bar, and in the forward path, the dam bar starting from the starting end of the dam bar along the forward path is predetermined. The laser beam is irradiated around the position of the distance to remove the dam bar, and the return path is irradiated with the laser beam around the position of a predetermined distance from the start end of the dam bar along the return path to remove the dam bar ( Claim 2).

Further, according to the present invention, the appearance of a dam bar at the light receiving position of the reflected light (or transmitted light) of the illumination light irradiated to the periphery including the laser beam irradiation position of the processing head and along the moving direction of the outward path or the return path. A photosensor having a spot-shaped sensitive area is provided at a position where the situation can be monitored, and the photosensor detects the start end of the dam bar along the moving direction of the forward or return of the dam bar, and the above-mentioned predetermined start from the detected start end. The laser beam is radiated around the position of the distance (Claim 3).

[0017]

According to the present invention, the dam bar processing of the semiconductor device is performed by reciprocating the semiconductor device and performing the dam bar processing on the forward path and the return path. This allows
Even if the dam bar pitch and the width of the dam bar are not uniform, it is possible to cleanly remove the dam bar from a position at a predetermined distance from both ends of the dam bar.

Further, according to the present invention, both end portions of the dam bar are detected by the photo sensor, and the laser beam is emitted around a position at a predetermined distance from the detected both end portions (claim 3). This allows the dam bar to be removed in a continuous reciprocating motion without relying on a pre-programmed sequence.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 4 is different from FIG.
This FIG. 4, which is characterized in that the value signal generating circuit 25 is newly provided, is the same as the prior application (Japanese Patent Application No. 4-293) filed by the present applicant.
No. 114). Photo sensor 2
4 is used for monitoring the position of the dam bar, and the binary signal generating circuit 25 detects the appearance of the dam bar from the output of the sensor 24.
Capture as a value signal. This binary signal is sent to the controllers 15 and 20 and used for timing control of laser irradiation. The prior application shown in FIG. 4 is such that when a series of dam bars on one side is removed, the work is continuously moved without stopping, and the dam bar can be removed at the center position of each dam bar in the process of this continuous movement. Is. In FIG. 2, the work is stopped for each dam bar and the opening / closing shutter is opened and closed. However, in the prior application shown in FIG. 4, the work is continuously moved and the shutter is opened without performing any of these operations. It remains on. In the prior application shown in FIG. 4, the photo sensor 24 detects the appearance position of each dam bar (the leading edge position of each dam bar) along with the movement of the work, and emits a laser beam from this leading edge position at the center position of the dam bar. Therefore, a laser beam is generated at this timing. The central part of one dam bar can be removed instantaneously with one laser beam,
The time required for this removal is a value that can be ignored compared to the unit moving time based on the moving speed. Therefore, even if the work is continuously moved, the dam bar is processed at high speed, which does not hinder the continuous movement of the work. Even if the leading edge position of the dam bar is not aligned, the leading edge position itself can be detected by the photosensor 24, and therefore the dam bar can be reliably removed without removing the center position of the dam bar.

A specific example of the photosensor 24 is shown in FIG. 1, and the construction of this photosensor is a development of the photosensor having the construction shown in FIGS. 6 and 7. In the following, an example of the photo sensor of FIGS. 6 and 7 will be described, and finally,
As an embodiment of the present invention, FIG. 1 and its handling example are shown in FIG.
It will be explained using the following. Note that there is an example of transmitted light instead of reflected light, and in this case, the photosensor 24 is provided on the transmission side.

An optical system including the photo sensor 24 is shown in FIG. The processing head 12 has a dichroic mirror 27,
The bending mirror 28, the condenser lens 29, and the imaging mirror 26 are incorporated. The laser beam from the laser head 14 passes through the bending mirror 28 and the work 1
Try to remove the dam bar above 0. On the other hand, the illumination light source 26
The illumination light is emitted from the dichroic mirror 27, the bending mirror 28, and the condenser lens 29 onto the lead frame. The reflected light enters the imaging lens 26 through the same optical path, enters the photosensor 24 provided on the fixing member 100 through the opening 100A, and forms an image of the state on the lead frame. The assist gas supply system during laser processing is omitted.

FIG. 6 is a diagram for explaining the size of the sensitive area of the photo sensor 24. The arrow indicates the moving direction (x direction) of the table. The size of the illumination light by the imaging lens 26 is the circular portion 30 in the figure. This circular part 30 is 1
Two dam bars 23 and a part of space portions (slit portions) 23A and 23B existing on both sides in the direction orthogonal to the moving direction and lead frames 22A on both sides in the direction along the moving direction,
A field of view including a part of 22B and one dam bar 23
It is large enough to show the situation around it, including.
This field of view also changes as the table 11 moves. On the other hand, the sensitive area of the photosensor 24 has a size as shown by a minute hatched circular portion, and this size is a spot-like value which is sufficiently smaller than the size of the dam bar 23. By making the sensitive area of this minute diameter, not only the appearance of the dam bar 23 due to the movement of the table 11 but also the appearance of the lead frames 22A and 22B on the left and right of the dam bar along the moving direction of the table 11 are closely tracked. Can be monitored. The movement of the table 11 causes the photosensor 24 to make a locus shown by the dotted line in FIG. 7, and the sensitive target area of the photosensor 24 changes one after another. By tracking this sensitive target area, the appearance of the dam bar appears. I know the position.

The tracking of the dam bar by the photo sensor 24 and the dam bar cutting timing will be described below. First I
The work 10 which is the lead frame of C is attached to the XY table 1
When the image is moved at a constant speed in the positive direction of the X axis by 1, the image formed by the reflected light from the work 10 which is focused on the target shown in FIG. 6 also moves in the positive direction of the X axis. However, since the photosensor 24 is fixed, the change in the detection signal output from the photosensor 24 is high in the space portion 23B (slit portion) as shown in FIG. 7, and the lead frame portion (web portion) is changed. ) 22
The output is low at A and 22B. However, the detection signal here has a high output when the light is strong and a low output when the light is weak. Further, as shown in FIG. 7, if the space portion 23B of the work 10 and the lead frame portions 22A and 22B are arranged at equal pitches, the XY table 11 moves at a constant speed, so the detection signal is detected as a waveform of a constant cycle. To be done. On the other hand, when the space portion 23B of the work 10 and the lead frames 22A and 22B are not arranged at equal pitches, the detection signal is detected as a waveform having a time change proportional to the pitch change.

Next, FIG. 8 shows a binarized signal generating circuit 25, FIG. 9 shows a portion relating to the main body of the laser controller 20, and FIG. 10 shows a waveform diagram of each portion thereof. Figure 8
The binarized signal generating circuit 25 includes a comparator 251 and a delay circuit 252. The comparator 251 compares the output of the photo sensor 25 with the threshold value TH. If so, "0" is output. The threshold value TH is selected so that the leading edge of the dam bar has a rising edge of "1" and the trailing edge portion thereof has a rising edge of "1". The delay circuit 252 delays the binarized detection signal by the delay time t ₁ instructed by the main controller 15 and sends it to the laser controller 20 as a first rectangular wave signal P. This delay time t
The meaning of ₁ will be described later.

The laser controller 20 shown in FIG. 9 includes an internal generator 201, a gate circuit 202, and a trigger circuit 203.
Consists of The gate circuit 202 is a rectangular wave signal generation circuit 25.
From the internal generator 201 and the first rectangular wave signal P from the main generator 15
Is selected by the control signal TP from the photosensor 24, and when the output of the photosensor 24 of this embodiment is used, the signal P is output at TP = 1, and when the photosensor output is not used, TP is output.
The signal G is output when = 0. The trigger circuit 203 generates a trigger signal corresponding to the rising edge of the rectangular wave signal input from the gate circuit 202, inputs the trigger signal to the switch unit 17, and oscillates the pulsed laser light according to the trigger signal.

FIG. 10 shows the waveform of each part of the circuits of FIGS. 8 and 9. The oscillation of the pulsed laser light of FIG. 9 is actually a pulse having a certain width, but the pulse width is other than that. Since it is much smaller than the width of the signal in FIG.

The output pulse G of the internal generator 201 output at TP = 0 is a pulse having a fixed cycle,
Laser oscillation is performed according to this fixed period. In the laser oscillation by the pulse G, the laser is emitted to the processing head or stopped by using the opening / closing of the opening / closing shutter described above. Therefore, the output pulse G is not used in this embodiment provided with the photosensor 24.

Next, the delay time t ₁ of the delay circuit 252 will be described. This delay time t ₁ is the time for the laser irradiation position to be at the center position of the dam bar as shown in FIG. Let v be the moving speed of the work, w be the width of the dam bar, and various delay times (gomparator 25
1 is the binarization processing time, the processing time by the laser controller 20, the delay time of the switch unit 17, the total delay time until the pulse laser light oscillation) is t ₂ , and the dam bar width w is the moving speed. When the moving time is t, the following relational expression is used to set the processing position to the central position of the dam bar.

[0029]

## EQU1 ## t = w / v = 2 (t ₁ + t ₂ ) When t ₁ is calculated from this,

## EQU2 ## t ₁ = 2 (w / v) -t ₂ . That is, the oscillation of the pulsed laser light is generated by the photo sensor 2.
It is performed (t / 2) time after the detection at 4 and this position is the center position of the dam bar. Here, t ₂ , w, and v are
Input in the main controller 15 in advance.

A processing procedure for cutting a dam bar of an IC having a dam bar on one side by the above operation will be described. First, the locus passing through the dam bar, the moving speed of the work 10, that is, the moving speed v of the XY table 11, the width w of the slit portion 23B of the work 10, and the delay time t ₂ are input to the main controller 15. or,
Since the dam bar cutting is performed here, the first rectangular wave signal P is input to the trigger signal 203 in the gate circuit 202 as the XY table 11 is moved, that is, the control signal TP = 1 is input to the gate circuit 202. As described above, the program is input to the main controller 15. When this program is run, the table 11 moves at a constant speed, and the pulsed laser light oscillates at a cycle determined by the pitch of the slit portion 23B and the moving speed v of the table 11,
Moreover, the irradiation is performed at the center of the slit portion 23B, and the dam bar is cut.

For example, when the laser oscillator used here is a pulse excitation type YAG laser, if the maximum oscillation frequency is set to a frequency of about 300 Hz, its period is 3.
Although it is about 3 ms, if the period determined by the pitch of the slit portion 3 and the moving speed v of the table 21 is set to this value, the time per dam bar cutting is 3.
It will be 3 msec, which can be drastically shortened compared to the conventional one.
When the pins are not evenly spaced, that is, when the pitches of the web portion and the slit portion are not constant, the pulsed laser light should be oscillated at a position separated from the end portion of the web portion by a preset distance. For example, the dam bar can be cut in the same manner. Further, even when the pins are not evenly spaced, the dam bar can be cut at a position separated from the end of the web portion by a predetermined distance. This position and the intermediate position in the case of the equal intervals are collectively referred to as a reference intermediate position.

I having the dam bars 2 on the four sides shown in FIG.
To efficiently cut the dam bar of C package
As shown in FIG. 2, four photosensors 24A to 24D are arranged at fixed positions indicated by w1 to w4 in the figure. Then, the binarized signal generation circuit 25 further selects a detection signal corresponding to the moving direction of the work 1 from the detection signals from the photosensors at the positions of w1 to w4, and the first detection signal based on the selected detection signal.
The rectangular wave signal of is input to the control means, and the subsequent processing is performed in the same manner as in the above-described embodiment. First, when cutting the dam bar 23 in the Q3 portion, the detection signal from the photosensor 24A at the position of w1 is selected in the binarized signal generating circuit as shown in FIG. 12A, and is sequentially cut in the X-axis direction. . Next, when cutting the dam bar 23 at Q2, the photo sensor 24 at the position of w2 as shown in FIG.
The detection signal from B is selected in the binarized signal generation circuit and sequentially cut in the positive direction of the Y axis. Thereafter, similarly, the portion of Q1 is sequentially cut in the negative direction of the X axis, and D
The part is sequentially cut in the negative direction of the Y-axis. In this way, all the dam bars 23 on the four sides can be continuously cut.

When the dam bar is cut using the above-mentioned photosensor, if the pitch of the dam bar and the width of the dam bar are not uniform because they are large or small, the dam bar will not be cut evenly. This state is shown in FIG. FIG. 13 is a top view of three adjacent dam bars 23 and the lead frame 24 interposed therebetween. Here, the dam bar pitch width P and the dam bar width W of each of the first dam bar shown on the left side and the second dam bar shown in the middle are as follows. First dam bar P = P ₀ (reference size) W = W ₀ (reference size) Second dam bar P = P ₀ ′ (P ₀ ′> P ₀ ) W = W ₀ ′ (W ₀ '> W ₀ )

Therefore, assuming that the semiconductor device moves in the direction of the arrow (outward path) in FIG. 13, according to the prior application, in each of the first dam bar and the second dam bar, from the leading edge of the dam bar (t / 2) The dam bar is cut at the position a after the moving time. As a result, in the first dam bar, the left and right remaining portions of the dam bar after cutting are equal and the width in the left-right direction itself is a small value, which is not a problem.
However, in the second dam bar, the remaining portion A on the right side significantly remains as shown in FIG. The presence of the remaining portion A on the right side deteriorates the quality and adversely affects the subsequent processes. For example, in the post process, there is a lead frame bending process,
During this bending, the remaining cutting part will be bent,
The bending is insufficient, which causes an error in the plane of the lead frame. Further, although there is a step of soldering to the lead frame, extra solder may be added to the remaining portion after cutting, resulting in a short circuit between the lead frames.

There is another problem. FIG. 13 shows an example in which the width D that can be cut by one laser beam with respect to the width W _{0 of} the dam bar is not so small (that is, W ₀ ≈2D). However, as shown in FIGS. 14A and 14B, there is a case where the width D'is sufficiently small (W ₀ >> D ') if the dam bar width W ₀ can be cut with one laser beam (W ₀ >>D'). Examples where one laser beam is narrowed and made smaller, or where the dam bar width is relatively large). In such a case, according to the method of the prior application, as shown in FIG. 14 (a), a delay time is given and the position at a distance L ₁ from the start edge of the dam bar, or the position shown in FIG.
As shown in 4 (b), the cutting point is the central position of the dam bar,
The delay time is set so that 14
In (a), the remaining part of the dam bar on the right side is large.
In the case of (b), the left and right of the dam bar remains that cannot be ignored.

Thus, in the case of W ₀ >> D ',
The remaining part of the dam bar becomes large, leaving quality deterioration and problems in the post process.

Therefore, in the present invention, not only the forward movement but also the backward movement is performed, and the delay time is given to both the forward movement and the backward movement so that the dam bar is cut.

FIG. 1 is a diagram showing the operating principle of the present invention.
It is a figure corresponding to FIG. First, while the table on which the semiconductor device is mounted is continuously moved in the forward direction, the reference dam bar width W ₀ is given as data, and the dam bar is removed around the position of the distance L from the left end of the dam bar.
In a dam bar having a reference dam bar width W ₀ , the position of the distance L is the center position of the dam bar. A series of dam bars are removed one after another by this forward movement, and then a backward movement is performed. Even in this backward movement, the reference dam bar width W ₀ is given as data. The photo sensor 2
4A detects the end of the dam bar, but unlike the forward movement, it detects the right end of the dam bar. And
The dam bar is removed centering on the position b at a distance L from the right end. In the second dam bar in the middle, the shaded portion B is removed, and in the first dam bar on the left side, the dam bar removed in the forward movement is repeatedly removed again due to the reference dam bar width (actually, it is already removed in the forward movement. Therefore, it only irradiates the laser beam).

By thus performing the outward path and the inward path, it is possible to remove the dam bar at a position at a predetermined distance L from both ends even with a wide dam bar. Further, even if the dam bar is narrower than the reference width W ₀ , there is no problem as long as the dam bar is larger than the width that can be removed by one laser beam.

FIG. 15 is a diagram showing the operating principle in the case where the dam bar width is relatively sufficiently larger than the width that can be removed by a laser beam in one shot, as in the example of FIG. In the outward movement, the dam bar is removed at a position at a distance L ₁ from the left end of the dam bar. In the return movement, the dam bar is removed at a position at a distance L ₁ from the right end of the dam bar. In either case, the photo sensor 24 or 24A is used. According to this figure, the central portion A'can also be removed. There are various methods for selecting the distance L ₁ , and the width of the remaining portion of the dam bar is selected to be a small value.

In order to realize the dam bar removal sequence by the reciprocating movement as shown in FIGS. 1 and 15, the XY drive table 1 is used.
1 may be moved according to the velocity pattern as shown in FIG. FIG. 16A is an example of a speed pattern. By giving speed patterns having different polarities on the outward path and the return path, first, the outward path is moved and the laser pulse as shown in FIG. The dam bars are removed by applying the laser pulses, and further forward movement is performed, and the laser pulses as shown in FIG. 16B are successively applied in the constant speed section to remove the dam bars. It goes without saying that all the laser pulses were obtained by giving a delay time such that the position at the distance L ₁ becomes the removal center.

In the above embodiment, it is assumed that the photosensor 24A determines the irradiation timing of the laser beam in the forward path and the backward path, but the irradiation timing of the laser beam in the forward path and the backward path is determined by other than this. There can be examples. For example, it is possible to remove the dam bar on the outward path and the return path by using the sequences (1) to (5) shown in FIG.

Although the laser oscillation is pulsed, continuous oscillation may be used. In such continuous oscillation, whether to irradiate the processing head with the laser beam is determined using the opening / closing shutter.

Further, when the position of the dam bar is displaced in the direction perpendicular to the moving direction, the laser beam may be irradiated while correcting the displacement in the direction perpendicular to the moving direction.

[0045]

According to the present invention, when the dam bar pitch or the width of the dam bar is not uniform, or when the width of the dam bar is too wide as compared with the removal width of the laser beam, a predetermined distance from both side ends of the dam bar is obtained. It is now possible to remove the dam bar leaving only the distance.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of dam bar processing by reciprocating movement according to the present invention.

FIG. 2 is a configuration diagram of a conventional dam bar processing apparatus using a laser beam.

3A and 3B are a top view of a QFP type semiconductor device and a diagram showing an example of dam bar processing.

FIG. 4 is an embodiment diagram of a dam bar processing device of the present invention.

FIG. 5 is a diagram showing an embodiment of an optical system incorporating the photosensor of the present invention.

FIG. 6 is a diagram illustrating an installation example of a photo sensor.

FIG. 7 is a detection waveform diagram of the photo sensor of FIG.

FIG. 8 is a diagram showing an embodiment of a binarizing circuit 25 of the present invention.

FIG. 9 is a diagram showing an embodiment of a laser controller 20 of the present invention.

FIG. 10 is a waveform chart of each part of the circuits of FIGS. 8 and 9.

FIG. 11 is a top view of a QFP type semiconductor device.

FIG. 12 is a diagram showing another arrangement example of the photosensors.

FIG. 13 is a diagram showing a dam bar processing example in the case where there are differences in the dam bar pitch and the dam bar width.

FIG. 14 is a diagram showing a dam bar processing example in the case where the dam bar width is larger than the removal width by the laser beam.

FIG. 15 is a diagram showing a dam bar processing example according to the present invention.

FIG. 16 is a diagram showing a reciprocating movement sequence.

[Explanation of symbols]

 10 Work (Semiconductor Device) 11 XY Table 12 Processing Head 13 Z Table 14 Laser Head 15 Main Controller 16 Laser Power Supply 24 Photo Sensor

Front page continuation (72) Inventor Shigeyuki Sakurai 650 Kazutachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Plant (72) Inventor Yoshiya Nagano 650 Jincho-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura in the factory

Claims (3)

[Claims] 1. A semiconductor device dam bar for removing a dam bar by irradiating a laser beam from a processing head to a dam bar connecting a lead frame of the semiconductor device in each of a forward path and a backward path of the semiconductor device. Processing equipment. 2. A semiconductor device is reciprocally moved, and a dam bar that connects a lead frame of the semiconductor device is irradiated with a laser beam from a processing head to remove the dam bar in each of the forward path and the backward path, and the forward path is also included. In order to remove the dam bar by irradiating a laser beam centered on a position at a predetermined distance from the start end of the dam bar along the outward path, the return path is centered on a position a predetermined distance from the start end of the dam bar along the return path. A semiconductor device dam bar processing device that irradiates a laser beam to remove the dam bar. 3. Reflected light (or transmitted light) of illumination light emitted to the periphery including the laser beam irradiation position of the processing head.
A photo sensor with a spot-like sensitive area is provided at the light receiving position of the position where the appearance of the dam bar along the forward or backward movement direction can be monitored, and this photo sensor is used to follow the forward or backward movement direction of the dam bar. 3. The dam bar processing apparatus for a semiconductor device according to claim 2, wherein the dam bar starting end portion is detected, and the laser beam is emitted around the position at the predetermined distance from the detected starting end portion.