JP2925952B2 - Dam bar processing device and dam bar processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dam bar cutting in which a semiconductor device is mounted on a lead frame and a semiconductor device integrally sealed with a resin mold is cut by a pulse laser beam. TECHNICAL FIELD The present invention relates to a dam bar processing device and a dam bar processing method capable of processing a high speed.

[0002]

2. Description of the Related Art In a semiconductor device in which a semiconductor chip is mounted on a lead frame and the lead frame and the semiconductor chip are integrally sealed by resin molding, a dam bar connects between the leads of the lead frame. When the frame and the semiconductor chip are integrally sealed, they play a role of blocking the resin mold from flowing out between the leads. The dam bar also has a role of reinforcing each lead. When the sealing by the resin mold is completed, the dam bar is cut and removed, and each lead (outer lead) of the lead frame is individually cut off. In the following description, a resin-molded semiconductor device in which a lead frame and a semiconductor chip are integrally sealed with the above-described resin mold is simply referred to as a semiconductor device.

Conventionally, this dam bar has often been cut by a punch press. However, recently, as the integration and performance of semiconductor devices have increased, lead frames have become more multi-pin and narrower in pitch. Since the dimensional accuracy is strictly required, the conventional punch press cannot technically cope.

On the other hand, recently, a method of cutting a dam bar using a laser beam has been developed. Since the laser beam can be narrowed down to a very small value, fine processing is possible. By simply irradiating the laser beam to the dam bar, the dam bar can be cut off in a non-contact manner, so that processing with high dimensional accuracy is possible. As a conventional technique for applying such processing by laser light (hereinafter, appropriately referred to as laser processing) to cutting of a dam bar, there is, for example, a technique described in Japanese Patent Application Laid-Open No. 6-142968.

In this prior art, a detection optical system (light detecting means) arranged substantially coaxially with a processing optical system optically detects the state of a workpiece (arrangement of leads), and outputs a detection signal in a rectangular shape. In addition, a predetermined delay time is given to the rectangular signal, and the oscillation of the pulse laser beam is controlled based on the signal with the delay time. In other words, the arrangement state of the leads is directly visually detected, and the pulsed laser beam is radiated using the data, whereby the pulsed laser beam can be reliably applied to the desired processing position, that is, the dam bar to be cut. Irradiation can cut the dam bar.

[0006]

In laser processing, a small condensed pulsed laser beam is applied to a processing position to be cut, and a workpiece is locally and instantaneously heated and melted. This is to blow off the melt to form a cut portion (cut groove). Therefore, at the time of laser processing, the fine particles of the melt are scattered as spatters, and laser plasma, plumes (also called fumes) and the like are simultaneously generated. This plume is a phenomenon that emits very bright light by laser plasma and an oxidation reaction caused by high-temperature heating. Further, part of the irradiated laser light is reflected or scattered.

Accordingly, when a detecting optical system (light detecting means) is arranged substantially coaxially with the processing optical system as described in Japanese Patent Application Laid-Open No. 6-142968, such scattering of spatter, laser plasma and plume The emission of light and the reflected or scattered laser light (hereinafter, appropriately referred to as disturbance light) hinder the reliable and accurate detection of the arrangement state of the leads by the light detection means.

Further, when a semiconductor chip is mounted on a lead frame and sealed with a resin mold, it is inevitable that the lead pitch deviates from a certain value due to the influence of shrinkage deformation of the resin mold. In particular, in a multi-pin semiconductor device, the size of the resin mold portion also becomes large. Therefore, even if slight deformation occurs in each lead, when many leads are viewed, they are accumulated, resulting in a large error.
In other words, even if the dimensional accuracy of each lead is ensured to some extent and is within the allowable error range, there may be cases where the error does not fall within the allowable error range due to the accumulation of errors when viewed from all leads. Further, in such a lead frame, the lead pitch is narrow and the plate thickness is thin, so that the rigidity is low and the lead frame is easily deformed. Therefore, the lead frame itself may be deformed during handling such as mounting the lead frame on a processing jig.

The prior art described in Japanese Patent Application Laid-Open No. 6-142968 does not take into account the shift in lead pitch due to the above-described deformation. That is, in the above prior art, the delay time to be given to the signal for controlling the oscillation of the pulsed laser light is a constant value regardless of the deformation of the lead frame, and the dimension of the lead gap (hereinafter, appropriately referred to as a slit portion), Even if the size of one dam bar changes individually, the pulse laser beam can always be irradiated only to a position at a fixed distance from the side surface of the lead (hereinafter, also appropriately referred to as a web portion).

In this case, the irradiation position of the pulsed laser beam may be more deviated to the lead side than the center of the dam bar (the center of the slit portion). The width increases. It is necessary to make the uncut width of the dam bar as small as possible, and the allowable value for quality control is determined, but if the irradiation position is biased, the uncut width may form a large width uncut portion.
Not preferred. In addition, if the above-described deviation increases, a notch may be formed in the lead (web portion) itself, and if the deviation further increases, the lead itself may be blown. Of course, it is absolutely necessary to avoid fusing the lead itself. However, if a notch is formed in the lead, the lead bending accuracy of the lead (outer lead) can be ensured in the subsequent process. The formation of such a notch should also be avoided, as it may cause breakage or breakage. Therefore, in order to obtain a high-precision and good shape by dam bar cutting, it is necessary to minimize the deviation of the irradiation position of the pulse laser beam.

A first object of the present invention is to provide a dam bar processing apparatus and a dam bar processing method for irradiating a desired processing position of a dam bar with a pulse laser beam based on a detection result of an arrangement state of a lead. It is an object of the present invention to provide a dam bar processing apparatus and a dam bar processing method capable of reliably and accurately detecting the arrangement state of leads without being affected by the above.

A second object of the present invention is to provide a dam bar processing apparatus and a dam bar processing method for irradiating a desired processing position of a dam bar with a pulse laser beam based on a detection result of an arrangement state of leads to perform processing. An object of the present invention is to provide a dam bar processing device and a dam bar processing method capable of reliably cutting the center and obtaining a highly accurate and favorable shape.

[0013]

According to the present invention, there is provided a laser oscillator for oscillating pulsed laser light, and the pulsed laser light is applied to a processing position of a workpiece. A processing optical system that guides the laser beam, a processing nozzle that emits the pulse laser light guided by the processing optical system, and a processing nozzle that is provided at an end with an opening for injecting an assist gas, and an optical axis of the pulse laser light that is processed. Transport means for moving the object relative to an object at a predetermined speed, and mounting the semiconductor device in which a semiconductor chip is sealed on a lead frame with a resin mold on the transport means, and placing the pulse laser on a dam bar of the lead frame. In a dam bar processing device that sequentially cuts a dam bar by irradiating light, the lead frame that precedes an optical axis of a pulsed laser beam irradiated to the dam bar is provided. A detection light generating means for irradiating a detection light at a position on the system to be reflected in a direction inclined in a direction opposite to a processing progress direction with respect to an optical axis of the pulse laser light; and the lead frame attached to the processing nozzle, A light detecting means for generating a corresponding detection signal by making the detection light reflected on and passing through the opening of the processing nozzle incident thereon, and a timing for irradiating the pulse laser light based on the detection signal from the light detection means. And a control means for controlling the laser oscillator so that the pulse laser light is irradiated to the center of the dam bar.

In the above dam bar processing apparatus, preferably, the control means includes a comparing means for binarizing the detection signal to generate a rectangular wave signal, and a rectangular shape for irradiating the center of the dam bar with the pulse laser beam. Delay means for giving a wave signal a delay time corresponding to the width of each dam bar.

In the above case, preferably, the position where the detection light is emitted by the detection light generating means precedes the optical axis of the pulse laser light by at least the width of the lead gap near the dam bar.

Preferably, the apparatus further comprises beam shape changing means for converting the pulse laser light oscillated from the laser oscillator into an elongated cross-sectional shape and rotating and displacing the pulse laser light cross-section around the optical axis.

In the above, preferably, the light detecting means comprises a plurality of detecting elements, and the detecting elements are arranged so as to be able to detect a range having a dimension longer than the width of the dam bar.

Preferably, the detection light generating means generates a detection laser light having an elongated cross-sectional shape, and a longitudinal dimension of the detection laser light cross section is longer than a width of the dam bar.

According to the present invention, in order to achieve the first and second objects, a pulse laser beam is applied to a dam bar of a semiconductor device in which a semiconductor chip is sealed on a lead frame with a resin mold. In the dam bar processing method of sequentially cutting the dam bar by moving the optical axis of the pulse laser light relative to the semiconductor device at a predetermined speed, the optical axis of the pulse laser light applied to the dam bar is Also, the detection light is irradiated on the lead frame at a position on the preceding lead frame so as to be reflected in a direction inclined in a direction opposite to the processing progress direction with respect to the optical axis of the pulse laser beam, and reflected on the lead frame. The detection light that has passed through the opening of the processing nozzle is made incident to generate a corresponding detection signal, and the pulse laser light is illuminated based on the detection signal. The timing of determining, dam bar machining method characterized in that said pulsed laser beam at the center of the dam bar in the timing to control the oscillation of the pulse laser beam to be irradiated is provided.

In the above, it is preferable that the pulse laser light is converted into an elongated cross-sectional shape, and that a spot size at the irradiation position of the pulse laser light in the longitudinal direction is sufficiently longer than the width of the dam bar. The pulse laser light is applied so that the longitudinal direction of the dam bar substantially coincides with the longitudinal direction of the lead of the lead frame and the dam bar is inserted in the width direction.

[0021]

In the present invention constructed as above, the position of the dam bar to be cut is detected and the cutting operation is performed while moving the workpiece at a predetermined speed by the transport means. At this time, the detection light from the detection light generating means is applied to a position on the lead frame that precedes the optical axis of the pulse laser light (hereinafter, referred to as the laser optical axis), and the reflected light is the light of the pulse laser light. The light is reflected in a direction inclined to the opposite side to the processing progress direction with respect to the axis. The reflected light reflected on the lead frame and passing through the opening of the processing nozzle enters the light detecting means. This makes it possible to detect the arrangement state of the leads (the presence or absence of the leads) at a position preceding the processing position where the pulsed laser beam is irradiated. Further, since the laser optical axis and the detection light are inclined with respect to each other, intense disturbance light such as spatter, reflected light of laser plasma, plume, and pulse laser light for processing is directly incident in the direction of the light detection means. Can be prevented.

Further, the light detecting means is attached to the processing nozzle, and the reflected light passing through the opening of the processing nozzle is made incident on the light detecting means, so that spatter, intense disturbance light, and dust coming from outside can be reduced. Most of the dust is blocked by the processing nozzle, and the light detection means is protected.
Furthermore, since the arrangement state of the lead at the position immediately before the laser optical axis is detected and the pulse laser light is immediately irradiated to perform the processing, it is difficult for external disturbance elements to enter from the time of detection to the time of processing. Suitable for fine processing. In addition, since the light detection means is integrally formed with the processing nozzle, the relative positional relationship between the laser optical axis and the position where the detection light is irradiated (hereinafter, referred to as a detection position) is fixed, and the processing nozzle is fixed. Even if vibration or deformation is caused by any cause or an attachment error occurs, the relative positional relationship between the laser optical axis and the detection position does not change, and the detection accuracy is maintained. Further, the structure of the light detecting means can be simplified, and the strength and durability are improved.

Further, in a semiconductor device, a cumulative error is a problem when viewed from a large number of leads due to shrinkage deformation of the resin mold as described above. However, when viewed from an individual lead, the error is extremely small. Is considered to be maintained. By utilizing this fact, the present invention detects the arrangement state of individual leads maintaining a certain degree of dimensional accuracy, determines the processing position for each dam bar based on the detection signal, and performs processing.

That is, the detection signal generated from the above-described light detection means is sent to the control means, and the timing for irradiating the pulse laser light is determined based on the detection signal. At that timing, the laser oscillator is controlled and the dam bar is controlled. The center is reliably irradiated with the pulsed laser light. As a result, the deviation of the irradiation position of the pulsed laser beam is eliminated, so that a large uncut portion is not formed after dam bar cutting, and the uncut portion can be kept within an allowable value for quality control. Further, a notch portion is not formed in the lead (web portion) itself, and the lead itself is not melted, so that it is possible to obtain a highly accurate and favorable shape.

In the above, the laser beam axis is relatively moved with respect to the workpiece by the conveying means at a predetermined speed, but the irradiation time of the pulse laser beam (hereinafter referred to as pulse width) is extremely short. Since the moving distance at that time is very small, the blown portion of the dam bar may be regarded as about the width of the spot. Therefore, when the laser optical axis is moved with respect to the workpiece, the oscillation time of the pulse laser light is obtained. Thus, the irradiation position is uniquely determined, the dam bar is sequentially cut, and processing can be performed reliably and at high speed.

In the present invention, the control means irradiates a pulse laser beam by the following processing. That is,
The detection signal is binarized by the comparing means into a square wave signal,
A predetermined delay time is given to the rectangular wave signal by the delay means, and the pulse laser light oscillates based on the predetermined delay time. If this delay time is appropriately selected according to the width of each dam bar, that is, the width of the lead gap (slit portion), the center of the dam bar can be accurately irradiated with the pulse laser beam.

In the above description, the detection position detects the end (end) of the lead (web portion), moves into the slit portion, moves, and when the start of the next lead is detected, the width of the slit portion is detected. That is, the length of the dam bar can be known. Here, since the detection position of the light detection means precedes the laser optical axis by at least the width of the slit portion near the dam bar, the laser optical axis is detected when the detection position detects the start of the lead. The position is behind the position (rearward) more than the width of the slit portion, that is, the position behind the start position of the slit portion. Thus, the length of the dam bar corresponding to the slit can be known before the laser optical axis reaches the position of the beginning of the slit. Based on the length of this dam bar, half the length, that is, the length from the starting position of the slit portion to the center of the dam bar is obtained,
The time to travel to the center of the dam bar is determined. Therefore, pulse laser light can be oscillated when the time from the time when the laser optical axis passes through the starting position of the slit portion to the center of the dam bar elapses, whereby the pulse is emitted to the center of the dam bar. Irradiation with laser light can be performed.

When the light detection means follows the above-described signal processing, the delay time of the delay means is the movement time of the preceding distance of the detection position with respect to the laser optical axis, and the optical axis passes through the beginning of the slit. Then, it is the sum of the time required to reach the center of the slit portion, that is, the center of the dam bar.

According to the present invention, the pulse laser beam is converted into a pulse laser beam having an elongated cross section by the beam shape changing means. At this time, the length in the longitudinal direction of the spot at the irradiation position of the pulse laser light is set to be sufficiently longer than the width of the dam bar, and the pulse laser light cross section, that is, the spot is appropriately rotated and displaced around the optical axis to extend the length. The direction is made substantially coincident with the longitudinal direction of the lead. Then, by damping the dam bar in the width direction, the dam bar can be reliably cut by a single irradiation of the pulse laser beam.

In the method of moving the workpiece and moving the detection position in the traveling direction while cutting the dam bar sequentially as in the present invention, the detection accuracy in the moving direction, that is, the direction orthogonal to the longitudinal direction of the lead, is improved. Therefore, the positioning accuracy of the laser optical axis is high, and the processing accuracy by the pulse laser beam in the direction orthogonal to the longitudinal direction of the lead can be sufficiently ensured. On the other hand, since the detection position is not moved in the longitudinal direction of the lead, it is difficult to ensure high positioning accuracy of the laser optical axis. However, by using a pulsed laser beam having an elongated cross-sectional shape as described above, by making the longitudinal dimension of the spot sufficiently longer than the width of the dam bar and making its longitudinal direction substantially coincide with the longitudinal direction of the lead, There is almost no problem even if the positioning accuracy of the laser optical axis in the longitudinal direction is not so high, and even if the laser optical axis is slightly shifted in the longitudinal direction of the lead, the dam bar is surely cut in the width direction by one irradiation. It is possible.

In the present invention, the light detecting means is constituted by a plurality of detecting elements, and the detecting elements are arranged so as to be able to detect a range having a dimension longer than the width of the dam bar. Change, and therefore the shape change on both sides of the longitudinal center line of the dam bar, can be easily detected, thereby accurately detecting the arrangement state of the leads and therefore the position of the dam bar to be cut without erroneous detection. It is possible to do. Also, for example, if the signals of the individual detection elements are compared with each other, it is possible to evaluate the validity of the detection operation state, measure the size of the aim of the detection position, control the amount of detection light at the detection position, detect failure of each detection element, etc. Can be performed.

In the above case, the detection light generating means generates a detection laser beam having a thin and long cross-sectional shape, and furthermore, makes the longitudinal dimension of the cross section longer than the width of the dam bar so that the dam bar can be detected in the width direction. The laser beam can be irradiated, and the shape change can be easily detected correspondingly.
Further, by using the detection laser light as the detection light, the change of the detection signal corresponding to the shape change can be sharpened, and the detection can be performed with high resolution and high accuracy.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a dam bar processing apparatus and a dam bar processing method according to the present invention will be described with reference to FIGS.

FIG. 1 is a view schematically showing a schematic configuration of a dam bar processing apparatus according to the present embodiment, and FIG. 2 is an enlarged view showing a part of FIG. As shown in FIG. 1, the dam bar processing apparatus according to the present embodiment includes a laser oscillator 10, a beam shape changer 11, a processing head 12, a processing nozzle 13, and a processing table 21 serving as a conveying means as a processing system. As a system, a detection signal amplifier 31, a level discriminator 32 as a comparison means, a lead frame shape discriminator 33, a delay circuit 34 as a delay means, a laser power supply circuit 35, a beam control section 36, a light source power supply 37, a table control section 38, and a control circuit 30.

The beam shape changer 11 includes a convex cylindrical lens 11a and a concave cylindrical lens 11b.
And a pulsed laser beam 10A from the laser oscillator 10.
Is converted into an elongated ellipse. Further, by adjusting the interval between the convex cylindrical lens 11a and the concave cylindrical lens 11b, the elliptical flatness of the cross section can be changed, and further, the beam shape changer 11 itself rotates around the optical axis of the pulse laser light. (In the direction of the arrow in the figure), the pulsed laser light 1
The elliptical section of 1A is rotationally displaced around the optical axis. The adjustment of these beam shape changers 11 is performed by the beam control unit 36.

The processing head 12 is provided with a bending mirror 14 and a camera 15, and the camera 15 is connected to a monitor television 15a. The camera 15 and the monitor television 15a are for visually observing an installation state before processing and a processing state during processing.

As shown in FIG. 2, the center axis of the processing nozzle 13 is perpendicular to the workpiece 1 (semiconductor device in which a semiconductor chip is mounted on a lead frame and integrally sealed with a resin mold). The processing nozzle 13 is provided with a condenser lens 16, an assist gas supply port 17, a detection light source 41, and a photodetector 42. The detection light source 41 irradiates a position preceding the laser optical axis 13C with the detection light 41A. Photodetector 4
Numeral 2 is integrally attached to the processing nozzle 13 so that the normal line of the light receiving surface is inclined with respect to the laser optical axis 13C of the pulse laser beam 13A.
a reflected light of the detection light 41A passing through the
A is incident. The photodetector 42 includes a bandpass filter 43, a detection lens 44, and a photosensor 45. Further, as shown by an arrow in FIG. 1, the entire processing nozzle 13 is rotatable with respect to the processing head 12 by a rotation mechanism 18. Adjustment of the rotation angle by the rotation mechanism 18 is performed in accordance with a command from the table control unit 38 in conjunction with the movement operation of the processing table 21, and even if the processing progress direction is changed, the light receiving surface of the photodetector 42 is adjusted. The line is always inclined to the side opposite to the processing progress direction with respect to the laser optical axis 13C.

Laser beam axis 1 in processing nozzle 13
FIG. 3 shows a geometrical relationship between 3C and the detection light 42A incident on the photodetector 42 in the inclination direction. As shown in FIG. 3, the detection light 42A is inclined by an angle β with respect to the laser optical axis 13C of the pulse laser light 13A condensed by the condenser lens 16. Laser optical axis 13C and detection light 42A
Are inclined with respect to each other, so that intense disturbance light such as sputter, laser plasma, plume, and reflected light of pulsed laser light for processing can be prevented from directly entering the photodetector 42. However, in this case, the processing progress direction is from the left to the right on the paper surface, and the vicinity of the intersection of the detection light 42A and the center line of the laser optical axis 13C corresponds to the position of the lower surface of the processing nozzle 13. The distance between the lower surface and the surface of the work 1 is represented by h.

Further, since the photodetector 42 is integrally attached to the processing nozzle 13 and the detection light 42A passing through the opening 13a of the processing nozzle 13 is made incident on the photodetector 42, spatter, strong disturbance light, Most of the dust and dust flying from the outside is blocked by the processing nozzle 13 and the photodetector 42 is protected. Further, since the detection light 42A is not captured outside the processing nozzle 13, the side surface of the processing nozzle 13 does not hinder the detection. Furthermore, since the arrangement state of the lead 3 at the position immediately before the laser optical axis 13C is detected and the pulse laser beam 13A is irradiated immediately to perform the processing, external disturbance elements occur between the detection and the processing. Difficult to enter. In addition, the laser optical axis 13
The relative positional relationship between C and the detection light 42A is fixed, and even if the processing nozzle 13 vibrates or deforms for some reason or an installation error occurs, the relative position between the laser optical axis 13C and the detection position P is increased. The positional relationship remains unchanged and the detection accuracy is maintained. Also, the photodetector 4
2 can be simplified, and the strength and durability are improved.

As shown in FIG. 3, the detection position P (intersection between the detection light 42A and the surface of the work 1) detected by the photodetector 42 precedes the focus position K of the pulse laser light 13A on the work 1. Although the distance (hereinafter referred to as the preceding distance) ΔL is small, it is set to be at least the width of the slit portion (W _{m in} FIG. 5) near the work 1, that is, the dam bar of the semiconductor device. That is, the detection position P precedes the laser optical axis 13C by at least the width of the slit near the dam bar. If the inclination angle β is too large, the error in the detection position increases even with a slight change in h. Therefore, it is not desirable to increase the angle β more than necessary.

The light emitting operation of the detection light source 41 and the adjustment of the light amount are performed by the light source power supply 37. If the detection light source 41 has a light amount sufficiently larger than the disturbance light, the influence of the disturbance light can be reduced. Further, as the detection light source 41, for example, visible light (wavelength: 0.4 to 0.
7 μm) or an Ar laser in the visible light region (wavelength: 0.5
14 μm) or He-Ne laser (wavelength: 0.633)
μm) are preferred. By using these, a CO ₂ laser (wavelength: 10.6 μm) often used as a pulse laser beam 13A (10A) for processing is used.
m) and the influence of reflected or scattered light of laser light such as a YAG laser (wavelength: 1.064 μm) can be reduced, and more reliable and accurate detection can be performed. In particular, since the beam of the Ar laser is difficult to spread and cannot reach the photodetector 42 if it deviates from the regular set position, it is possible to detect the roundness of the set position by using this fact, further improving the detection accuracy. it can. The bandpass filter 43 selectively transmits only light having a required wavelength, and thereby can eliminate the influence of disturbance light as much as possible.

The work table 21 mounts the work 1 which is a work to be processed, and moves the work 1 in a horizontal plane (this is defined as an XY plane) in accordance with a command from the table control unit 38. The processing table 21 is composed of an X table 22, a Y table 23 and a θ table 24 as shown in FIG. 4, and the workpiece 1 is moved by the X table 22 and the Y table 23 with respect to the laser optical axis 13C during normal dam bar processing. To move. table 24 is used to correct a rotation angle error in the XY plane among errors in the mounting position of the work 1 after the work 1 is mounted on the processing table 21. That is, the center line in the longitudinal direction of the dam bar 5 is made to substantially coincide with the X axis or the Y axis.
The number of axes to be controlled at the time of cutting the dam bar 5 can be reduced, and processing can be performed with high dimensional accuracy by controlling only one axial direction, that is, the feed direction.

In the above configuration, the laser oscillator 10 emits a pulse laser beam 10 A under the control of the laser power supply circuit 35. And the beam shape changer 1
1 and a pulsed laser beam 11 incident on the processing head 12
A is changed in direction by the bending mirror 14, is condensed by the condensing lens 16, becomes a pulsed laser beam 13A, passes through the opening 13a at the tip of the processing nozzle 13, and is irradiated onto the work 1. Further, the detection light 41A emitted from the detection light source 41 is applied to the detection position P on the surface of the work 1 and then reflected, becomes the detection light 42A, and enters the photodetector 42. An unnecessary wavelength portion of the detection light 42A that has entered the photodetector 42 is removed by a bandpass filter 43, and is condensed on a photosensor 45 by a detection lens 44. From the photo sensor 45, an electrical detection signal including information on the surface of the work 1, that is, information on the arrangement state of the leads in the semiconductor device is issued. Here, if the above-described laser light is used as the detection light 41A, the rise (response) of the detection signal (see FIG. 7) based on the information of the arrangement state of the leads on the surface of the work 1 (the presence or absence of a material or a change in shape) Is sharp, and high-precision detection with high resolution can be performed.

The assist gas 17 A supplied from the assist gas supply port 17 is supplied to the opening 13 of the processing nozzle 13.
Injected from a. The assist gas 17A is generally used not only in the present embodiment but also when performing laser processing as fusing processing, and is used to blow off most of the melt and perform good processing. . The diameter of the opening 13a of the processing nozzle 13 is suitably 0.5 to 1.5 mm, and the distance h between the tip of the processing nozzle 13 and the work 1 is preferably in the range of 0.5 to 1.5 mm. In particular, by setting the distance h between the tip of the processing nozzle 13 and the work 1 in the above range, good processing results can be obtained, and an accident that the processing nozzle 13 comes into contact with the surface of the work 1 or a foreign substance adhered on the surface is prevented. Can be avoided.

Furthermore, the injection of the assist gas 17A inside the processing nozzle 13 prevents spatter, dust, dust, and the like from entering the inside of the processing nozzle 13, and the sputter, dust, dust, and the like enter the photodetector 42. It is prevented from sticking. In general, the photosensor 45 of the photodetector 42 generally has low heat resistance. However, since the air cooling effect by the assist gas 17A can be expected to some extent, damage due to heat can be avoided.

The laser power supply circuit 35,
The beam controller 36, the power source 37 for the light source, and the table controller 38 are controlled by the control circuit 30.

Next, the operation of cutting the dam bar on one side of the semiconductor device by the above dam bar processing apparatus will be described. First, the structure of the work 1, that is, the semiconductor device is shown in FIG.
This will be described with reference to FIG. In FIG. 5A, in a semiconductor device 1, a semiconductor chip (not shown) is mounted on a lead frame 2 and corresponding terminals are electrically connected to each other with a gold wire or the like, and then integrally sealed with a resin mold 4. It is stopped. The dam bar 5 is provided between the leads 3 of the lead frame 2 to prevent the resin from flowing out between the leads when the resin mold 4 is sealed, and to reinforce each lead 3.
In this embodiment, the dam bar 5 is cut and removed by the dam bar processing device. However, FIG. 5 (a) shows a case where the dam bar 5 is not cut, and the semiconductor device 1 is strictly in the process of being manufactured. The device at the stage of is referred to as a semiconductor device.

The resin mold 4 of such a semiconductor device 1
If there is shrinkage deformation during sealing, a large number of leads 3
, The accumulated error is a problem. However, the error is very small for each lead 3, and it is considered that a certain degree of dimensional accuracy is maintained. In this embodiment, utilizing this fact, the arrangement status of the individual leads 3 for which a certain degree of dimensional accuracy is maintained is detected, and the processing position for each dam bar 5 is determined based on the detection signal, and the processing is performed. Do.

FIG. 5B is an explanatory view of the processing state of the dam bar 5, and is an enlarged view of a portion B in FIG. 5A. Upon cleavage of the dam bar 5 moves the workpiece 1 by the processing table 21, is relatively moved at a constant speed v ₀ of the position with respect to the workpiece 1, for example, in the positive direction of the X axis of the processing nozzle 13. However, the X axis and the Y axis are determined as shown in the figure. In many cases, the width of the slit 6 is almost equal to the width of the lead 3 in a semiconductor device.

At this time, the irradiation range 41B of the detection light 41A
Is longer than the width d of the dam bar 5 as shown in FIG. By setting the irradiation range 41B in this manner, information on a specific detection position near the dam bar 5 can be easily detected by the photodetector 42. By appropriately operating the beam shape changer 11 described above, the pulse laser beam 1
The spot 13B at the irradiation position of 3A is set so that its longitudinal dimension is sufficiently longer than the width d of the dam bar 5 as shown in FIG.
And the length direction substantially coincide. And spot 13B
Over the width d of the dam bar 5. Thereby, the dam bar can be cut in the width direction by one irradiation of the pulse laser beam 13A.

In the method in which the detection position P is moved in the moving direction of the work 1 while moving the work 1 and the dam bar 5 is sequentially cut as in this embodiment, the moving direction, ie, the lead 3
Therefore, the detection accuracy in the direction perpendicular to the longitudinal direction of the lead 3, that is, the positioning accuracy of the laser optical axis 13C is high, and the processing accuracy by the pulse laser beam 13A in the direction perpendicular to the longitudinal direction of the lead 3 can be sufficiently ensured. On the other hand, since the detection position is not moved in the longitudinal direction of the lead 3, it is difficult to ensure high positioning accuracy of the laser optical axis 13C. However,
By using the pulse laser beam 13A having an elongated cross section as described above, by making the longitudinal dimension of the spot 13B sufficiently longer than the width of the dam bar 5, and making the longitudinal direction substantially coincide with the longitudinal direction of the lead 3. Even if the positioning accuracy of the laser optical axis 13C in the longitudinal direction of the lead 3 is not so high, there is almost no problem. Even if the laser optical axis 13C is slightly displaced in the longitudinal direction of the lead 3, the dam bar 5 can still be irradiated by one irradiation. It is possible to cut in the direction of the width d.

FIG. 6 is a view showing the arrangement of the photosensitive surface of the photosensor 45 in the photodetector 42. As shown in FIG. 6, a plurality of photo sensors 45 (1, 2, 3,..., I-
The detection element 45a of (1), i) is constituted by a line photosensor in which the detection elements 45a are arranged on a straight line. The photo sensor 45 includes the dam bar 5 and is arranged so as to be able to detect a range having a dimension sufficiently longer than the width d of the dam bar 5. However, the two-dot chain line in the figure corresponds to the shape of the dam bar 5. For example, the detection elements 45a (hatched in the figure) with 1, 2, 3, 4 and i-3, i-2, i-1, i are low because there is no reflected light from the surface of the dam bar 5. Level (dark state), and other detection elements 45a (those not shaded in the figure) become high levels (bright state) due to the reflected light from the surface of the dam bar 5, thereby leading to the lead near the dam bar 5. , That is, the presence or absence of a read is detected.

Returning to FIG. 5B, in order to perform good dam bar cutting, the laser optical axis 13C is relatively moved on the longitudinal center line of the dam bar 5, that is, on the locus A ₁ -A _2. is necessary. However, in the unprocessed state, this locus A
Since ₁ -A ₂ no shape change over, on the trajectory is impossible to detect the arrangement state of the lead. On the other hand, if the detection position P is moved along the trajectory B ₁ -B ₂ or the trajectory C ₁ -C ₂ slightly away from the trajectory A ₁ -A ₂ , the arrangement state of the leads can be detected.

For this reason, of the detection elements 45a in FIG.
For example, the detection result (detection signal) of the one with 1 or 2 or i-1 or i is used. In addition, when the trajectory of the laser optical axis 13C deviates from A ₁ -A _2, it is possible to quickly detect the deviating state from the change state of the detection signal level from each detection element 45a. Thus, erroneous detection of the arrangement state of the leads can be avoided. As described above, by configuring the photo sensor 45 with a large number of detection elements 45a, the reliability of the detection operation near the processing position can be improved. However, usually, the end face of the lead 3 near the dam bar 5 is often provided with an R, which may affect the detection, so that the locus B ₁ -B ₂ or C ₁ -C of the detection position P is considered. ₂ is this R
It is desirable to set so as to cross at least the parallel portion of the lead avoiding the above. Furthermore, since resin burrs exist on the resin mold 4 side of the dam bar 5 and may affect the detection accuracy, it is more preferable to select B ₁ -B ₂ as the trajectory of the detection position P.

Further, for example, by comparing the signals of the individual detection elements 45a with each other, it is possible to evaluate the validity of the detection operation situation, measure the size of the aim of the detection position P, control the amount of detected light at the detection position P, Failure detection of the detection element 45a can be performed.

The detection signal from the photodetector 42 is sent to the detection signal amplifier 31 and amplified. The following signal processing will be described with reference to FIG. 1, FIG. 7 and FIG. Detection signal S from photodetector 42 amplified by detection signal amplifier 31
The change of ₁ results in a high output at the lead (web portion) 3 and a low output at the slit portion 6 as shown in FIG. However,
the width of the m-th slit portion 6 and W _m. Thereafter, the signal S ₁ is input to the level determiner 32, and a predetermined threshold value E is set by a comparator built in the level determiner 32.
It is binarized by ₀ (S ₂ ), and the lead frame shape discriminator 33
Is input to

[0057] Lead frame shape discriminator 33 is composed of a differential circuit, the signal S ₃ corresponding to the rise and fall of the signal S ₂ from the level comparator 32 in the differentiating circuit is created. Here, t _m in FIG. 7 is the width W _{m of the} slit 6.
At the speed v ₀ , and t _m = W _m / v ₀ . Width of the m-th slit section 6 at this stage, that is, the length W _m of the dam bar was measured. Above, the signal S ₃ is inputted to the delay circuit 34.

The delay circuit 34 is constituted by a microcomputer.
As shown in FIG. 8, a first integration counter 34a, a subtraction counter 34b, a first hold circuit 34c, a second integration counter 34d, and a second hold circuit 34e are provided. In the delay circuit 34, first, the lead frame shape discriminator 33
Signal S ₄ is produced in the first integrating counter 34a corresponds to the signal S ₃ from. In the first integrating counter 34a, integrated into the signal S ₃ is positive pulse output period from time T _m0 having issued (corresponding to the beginning of the slit portion 6) to emit a negative pulse output (between t _m) Is performed, and then the integrated value is held until the next positive pulse output,
When the next positive pulse output is issued, the integrated value is reset and the integration is performed again. In this case, the microcomputer of the clock time of the delay circuit 34 (unit oscillation period for processing) and Delta] t, but the number of clock time Delta] t between t _m is t _m / Delta] t, integrated in the signal S ₄ The value _nm is determined so as to satisfy 1/2 of the above-mentioned t _m / Δt, that is, the following equation (1).

[0059]

(Equation 1)

The value of n _m is a value that is half of the number of clock times Δt that are carved while moving between W _m (t _m ). Therefore, the integration up to the value of _nm by the first integration counter 34a means that the center (W _m / 2) of the m-th dam bar 5 (length W _m ) is obtained, and thus the beginning of the slit portion 6 is detected. it and is equivalent to obtaining the time T _m0 time to center of the dam bars 5 from (t _m / 2).

Next, the signal S ₅ is generated by the down counter 34b corresponds to the signal S _4. This subtraction counter 3
In 4b, the operation of starting the subtraction from the reference value N from the integration start time _Tm0 of the first integration counter 34a and the operation of setting the reference value N again when it becomes 0 (time _Tm1 ) are repeated. . Here, the reference value N in the signal S _5,
Using the preceding distance (the distance of PK in FIG. 3) ΔL, the distance is determined so as to satisfy the following equation.

[0062]

(Equation 2)

The reference value N represents the number of clock times Δt that are engraved while moving the preceding distance ΔL. Therefore,
The subtraction of the reference value N from the value of the reference value N to 0 by the subtraction counter 34b is _equivalent to the delay time t during the movement of the preceding distance ΔL at the time T _m0 when the start of the slit section 6 is detected by the photodetector 42.
It is equivalent to adding _L. Here, t _L = ΔL / v ₀ . Under this condition, the laser optical axis 13C comes to the position of the beginning of the slit portion 6 at a time T _m1 after the delay time t _L from the detection of the beginning of the slit portion 6 by the photodetector 42.

[0064] Here, the detection position P with respect to the laser optical axis 13C is ahead or width W _m of the slit 6, namely by a _{ΔL ≧ W m, t L ≧} t m , and the photodetecting When the detector 42 detects the beginning of the lead 3 (T _m0 + t
_m ), the laser optical axis 13C moves from the detection position P by ΔL (≧
W _m ) behind. Thereafter, the laser optical axis 13C further moves to reach the position where the slit portion 6 starts (time T _m1 ). Signal processing in the following next first hold circuit 34c, to the time T _m1, what gives time laser optical axis 13C is moved from the beginning of the slit portion 6 to the center of the dam bar 5 (t _m / 2) as the delay time It is.

That is, the signal S _{5 is} output from the first hold circuit 34c.
First hold signal S ₆ is generated corresponding to the. In the first hold circuit 34c, no pulse is generated while the subtraction is performed in the subtraction counter 34b (time T _{m0 to} T _m1 ), and the pulse is generated only while the reference value N is held in the subtraction counter 34b. generate.

[0066] Subsequently, the signal S ₇ is created in the second integrating counter 34d on the basis of the first hold signal S _6. In the second integration counter 34d, the first hold signal S ₆
Accumulated from the rising time T _m1 until the integrated value n _m is performed,
After being held, the accumulated again performed is reset at the rising edge of the first hold signal S ₆ follows. Integrated value n _m at this time is given from the first integration counter 34a.

[0067] Further, the second hold signal S ₈ is created in the second hold circuit 34e on the basis of the signal S _7. In the second hold circuit 34e, the second integrating counter 34
The pulse is not generated while the integration is being performed at d, but is generated only while the integrated value _nm is held in the second integration counter 34d. In the second hold signal S _8, the time T that the integration until the integrated value n _m completed
_m2 is a delay time t _L during the movement of the preceding distance ΔL at time T _m0 when the start of the slit section 6 is detected by the photodetector 42.
(Time T _m1 ), and a delay time t _m / 2 for moving to the center of the m-th dam bar 5 is added.
In the above description, the lead frame shape discriminator 33 and the delay circuit 34 are described as separate circuits. However, since these processes can be easily realized by a one-chip microcomputer, the lead frame shape discriminator 33 and the delay circuit 34 May be put together as one circuit constituted by a microcomputer.

The second hold signal S ₈ from the delay circuit 34 is input to the laser power supply circuit 35 shown in FIG. The laser power supply circuit 35, a laser trigger for signal is generated based on the rising (time T _{m @ 2)} of the second hold signal S _8, which is input to the laser oscillator 10, a pulse laser beam 10A is oscillated. Through the above signal processing, the center of the dam bar 5 can be irradiated with the pulse laser beam 13A. In FIG. 7, the center of the dam bar 5 is not located on an extension of the oscillation time of the pulse laser light. However, this is because the position of the dam bar 5 in FIG. Because it is ahead of the oscillation time of t by t _L ).
If it is desired to know the position of the dam bar 5 in accordance with the oscillation time of the pulse laser beam, the position of the dam bar 5 in FIG. 7 may be shifted in the positive direction of the horizontal axis by t _L.
It can be understood that the oscillation of the pulse laser light is performed at the center of.

In the above description, the pulse width of the pulsed laser beam is actually extremely short, about 0.1 to 1 msec, during which the laser optical axis 13C moves relatively to the workpiece 1. Very small, dam bar 5
May be regarded as the width of the spot 13B. Therefore, when the laser beam axis 13C is relatively moved at the speed v ₀ by the processing table 21 while oscillating the pulse laser light, the irradiation position is uniquely determined by the oscillation time of the pulse laser light 13A, and the dam bar 5 Is cut, and processing can be performed reliably and at high speed.

Further, since the center of the dam bar 5 is irradiated with the pulse laser beam 13A, the irradiation position is not biased, and the uncut widths w ₁ and w ₂ of the dam bar 5 in FIG. 5B become substantially equal. Therefore, it is possible to avoid forming a large uncut portion after the dam bar 5 is cut, and it is possible to obtain a high-precision and good shape by keeping the uncut portion within an allowable value for quality control. Further, it is possible to prevent an accident in which a cutout portion is formed in the lead 3 itself or the lead 3 itself is melted.

In FIG. 7, after the start of the slit portion 6 is detected by the photodetector 42, the pulse laser beam 10A
The time used for signal processing until oscillation is T _m2 −T _m0
In this time, the detection signal is signal-processed according to the above-described procedure, and a time margin for stably and reliably oscillating the pulse laser light can be secured.

[0072] In the above description, the detection position P with respect to the laser optical axis 13C is a that precedes or width W _m of the slit portion 6 ([Delta] L ≧ W _m), theoretically even [Delta] L <W _m Can perform the same signal processing as described above. in this case,
It is necessary to add ΔL to the equation (1) indicating _nm and change it. However, in the case of ΔL <W _m , t _L <t _m , and the time (T _m0 +
At t _m ), the laser optical axis 13C has already entered the slit portion 6, and the time margin for signal processing is reduced. Therefore, it is desirable to ΔL ≧ W _m.

FIG. 9 and FIG. 1 show a procedure for cutting all the dam bars of the semiconductor device by repeating the signal processing as shown in FIG.
0 will be described. FIG. 9 is a diagram illustrating an example of a movement locus of the processing nozzle 13 when cutting all the dam bars 5 of the semiconductor device 1. This is also a diagram showing the movement locus of the laser optical axis 13C. However, as mentioned above,
Actually, it is assumed that the processing nozzle 13 does not move but the processing table 13 moves to move the processing nozzle 13 relatively to the semiconductor device 1.

As shown in FIG. 9, reference holes 7a to 7a are provided at positions where the extension lines of the dam bar 5 on each side of the lead frame 2 intersect.
The movement is started from, for example, the position of the reference hole 7a. First, moving the machining nozzle 13 along a trajectory D ₁₀ from the reference hole 7a, a constant speed movement speed before reaching this time reference hole 7b (the v _0). Then, the trajectory D ₁₁ from the reference hole 7b at a constant speed v ₀
The dam bar 5 is cut as shown in FIGS. 5 and 7 while moving the processing nozzle 13 along. Furthermore, the reference hole 7
along the a trajectory D ₂₀ moves the machining nozzle 13 to the reference hole 7c, for cutting the dam bars 5 while moving along the trajectory D ₂₁ at a constant speed v _0. Thereafter, the reference hole 7d locus D ₃₀ from reference hole 7b, locus D _31, reference holes 7d, locus D _40, reference holes 7c, locus D _41, all the while sequentially moving the machining nozzle 13 along the reference hole 7a Cut the dam bar 5. In the above, the trajectories D ₁₀ , D not on the dam bar 5
₂₀ , D ₃₀ , and D ₄₀ are the approach sections until reaching the constant speed v ₀ , respectively.

When cutting the dam bar 5 as described above, the beam shape changer 11 (see FIG. 1) is appropriately operated,
The longitudinal direction of the spot 13B of the pulse laser beam 13A is connected to the dam bar 5 on each side of the semiconductor device 1 by a lead 3.
And the length direction substantially coincide.

When cutting the dam bar, for example, as shown in FIG. 10, three semiconductor devices 101 to 103 are integrated, and a plurality of integrated semiconductor devices are fixed to a suitable holder 100, and 100 may be mounted on the processing table 21 as a work. The movement locus of the processing nozzle 13 at this time can be arbitrarily selected based on FIG. Further, the semiconductor device is not limited to three as shown in FIG. 10, and a plurality of semiconductor devices other than three may be handled collectively, for example, three integrated semiconductor devices are integrated into a total of nine. Thereby, the productivity of the semiconductor device including dam bar cutting is improved, and the lead frame is prevented from being deformed due to handling or the like in the middle of the manufacturing process, and a highly accurate and favorable shape can be maintained.

According to the present embodiment as described above, the detection light 4
Since 1A is irradiated to a position preceding the laser optical axis 13C, it is possible to detect the arrangement state of leads at the position preceding the position to be actually processed (the presence or absence of a lead). Further, since the detection light 42A from the direction inclined in the direction opposite to the processing progress direction with respect to the laser optical axis 13C is made incident on the photodetector 42, spatter and strong disturbance light are generated by the photodetector 4.
2 can be prevented from directly entering. Further, since the photodetector 42 is integrally attached to the processing nozzle 13 and the detection light 42A passing through the opening 13a of the processing nozzle 13 is made incident on the photodetector 42, spatter, strong disturbance light,
Furthermore, the photodetector 42 is protected from most of the dust and dust flying from the outside, so that the side surface of the processing nozzle 13 does not become an obstacle at the time of detection, and an external disturbance element hardly enters. Further, the structure of the photodetector 42 can be simplified, and the strength and durability can be improved. Further, the relative positional relationship between the laser optical axis 13C and the detection position P is fixed,
The accuracy of detection is maintained.

Also, the injection of the assist gas 17A prevents spatter, dust, dust and the like from adhering to the photodetector 42, and the air cooling effect of the photosensor 45 can be expected.

Further, even if the resin mold 4 contracts and deforms, the arrangement status of the individual leads 3 maintaining a certain degree of dimensional accuracy is detected, and the processing position for each dam bar 5 is determined based on the detection signal. Therefore, high-precision processing can be performed. Then, the pulse laser beam 13A
Sequentially dam bars 5 only by relatively moving the laser beam axis 13C at the speed v ₀ is cut by the processing table 21 while oscillating the, perform the machining reliably and fast.

In the signal processing according to the present embodiment, the level discriminator 32 detects the detection signal S ₁ based on the read arrangement state.
Is converted into a signal S ₂ , and the lead frame shape discriminator 33 and the delay circuit 34 delay the time (t) for moving the preceding distance ΔL between the detection position P and the light condensing position K.
_L) and the delay time to move to the center of the dam bars 5 (t _m /
Since 2) is given and the oscillation of the laser oscillator 10 is controlled by this, the center of the dam bar 5 can be accurately irradiated with the pulse laser beam 13A. As a result, there is no deviation in the irradiation position, and the uncut widths w ₁ and w _{2 of the} dam bar 5 are substantially equal, and the uncut width is within an allowable value for quality control to obtain a high-precision and good shape. Becomes possible. Further, it is possible to prevent an accident in which a notch is formed in the lead 3 itself or the lead 3 itself is blown.

Further, the beam shape changer 11 is appropriately operated so that the longitudinal dimension of the spot 13B of the pulse laser beam 13A is sufficiently longer than the width d of the dam bar 5, and the longitudinal direction of the spot 13B is adjusted. Since the spot 13B is made substantially coincident with the longitudinal direction of the lead 3 so that the spot 13B crosses the width d of the dam bar 5, the dam bar 5 can be cut in the width direction by a single irradiation of the pulse laser beam 13A. In this case, there is almost no problem even if the positioning accuracy of the laser optical axis 13C in the longitudinal direction of the lead 3 is not so high, and even if the laser optical axis 13C is slightly displaced in the longitudinal direction of the lead 3, the dam bar can be irradiated by one irradiation. Can be reliably cut in the width direction.

Further, the photo sensor 45 of the photodetector 42 is composed of a plurality of detection elements 45a, which are arranged so as to detect a range having a dimension longer than the width of the dam bar 5, so that the width of the dam bar 5 is reduced. Changes can be detected. Further, it is possible to detect the deviation of the trajectory of the laser optical axis 13C more quickly than the state of change of each detection signal level, and it is possible to avoid erroneous detection of the arrangement state of the leads.
Further, it is also possible to evaluate the validity of the detection operation status, measure the size of the aim of the detection position P, control the amount of detection light at the detection position P, and detect a failure of each detection element 45a.

The irradiation range 41B of the detection light 41A is
Since the width d of the dam bar 5 is set to be longer than the width d of the dam bar 5, information of a specific detection position near the dam bar 5 can be easily detected by the photodetector 42. Furthermore, if a laser beam is used as the detection light 41A, the rise of the detection signal based on the information on the arrangement state of the leads 3 becomes sharp, and high-precision detection with high resolution can be performed.

In the case where the dam bar does not penetrate (cannot be completely cut) by one irradiation of the pulse laser light, it is necessary to cut by several times of irradiation of the pulse laser light. In this case, the processing along the trajectory described above may be repeated several times.

[0085]

According to the present invention, since the detection light is applied to a position on the lead frame that precedes the laser optical axis,
The arrangement state (the presence or absence of a lead) of the position lead preceding the processing position can be detected. In addition, since the detection light from the direction inclined in the direction opposite to the processing progress direction with respect to the laser optical axis is made incident on the light detection means, it is possible to prevent spatter and disturbance light from being directly incident on the light detection means. Also,
The light detection means is attached to the processing nozzle, and the reflected light passing through the opening of the processing nozzle is made incident on the light detection means, so that the light detection means is protected from spatter, disturbance light, etc. Thus, the structure of the light detecting means can be simplified, and the strength and durability can be improved. Further, the relative positional relationship between the laser optical axis and the detection position is fixed, and the detection accuracy is maintained.

Further, the assist gas prevents spatter or the like from adhering to the light detecting means, and an air cooling effect of the light detecting means can be expected.

Further, the arrangement status of the individual leads whose dimensional accuracy is maintained to some extent is detected, and the irradiation timing is controlled based on the detected signal so that the center of each dam bar is irradiated with the pulsed laser beam. Therefore, it is possible to cut the center of the dam bar with high accuracy and reliability. As a result, the irradiation position is not biased, and the uncut width of the dam bar is substantially equal, so that a highly accurate and favorable shape can be obtained. In addition, it is possible to prevent an accident in which a notch is formed in the lead itself or the lead is melted. Furthermore, the dam bars are sequentially cut only by relatively moving the optical axis while oscillating the pulsed laser light, so that processing can be performed reliably and at high speed.

Further, since the detection signal based on the lead arrangement state is binarized, a predetermined delay time is given thereto, and the pulse laser light is oscillated based on the binarized signal, it is possible to accurately irradiate the center of the dam bar with the pulse laser light. Can be.

Further, the pulse laser beam is converted into a pulse laser beam having an elongated cross section by the beam shape changing means,
Moreover, the length of the spot in the longitudinal direction is made sufficiently longer than the width of the dam bar, and the longitudinal direction is made substantially coincident with the longitudinal direction of the lead so that the dam bar is passed in the width direction. The dam bar can be cut in the width direction by irradiation with laser light. in this case,
Even if the positioning accuracy of the laser optical axis in the longitudinal direction of the lead is not very high, there is almost no problem.Even if the optical axis of the pulsed laser light is slightly shifted in the longitudinal direction of the lead, the irradiation of the dam bar can be performed with a single irradiation. It is possible to cut in the direction.

Further, the light detecting means is composed of a plurality of detecting elements, and the detecting elements are arranged so that a range of a dimension longer than the width of the dam bar can be detected. Can be detected. In addition, it is also possible to evaluate the validity of the detection operation status, measure the size of the aim of the detection position, control the amount of detection light at the detection position, and detect a failure of each detection element.

Further, since the detection laser beam is applied to a range longer than the width of the dam bar, the shape change can be easily detected. Also, if the detection laser light is used as the detection light,
The change in the detection signal corresponding to the shape change can be sharpened, and high-precision detection with high resolution can be performed.

Therefore, according to the present invention, a high-quality and high-accuracy semiconductor device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a schematic configuration of a dam bar processing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a part of the dam bar processing device of FIG. 1;

FIG. 3 is a diagram showing a geometrical relationship between a laser optical axis and an inclination direction of detection light in the processing nozzle of FIGS. 1 and 2;

FIG. 4 is a diagram showing a configuration of a processing table in FIG. 1;

5A is a plan view of a work, that is, a semiconductor device, and FIG. 5B is an explanatory diagram of a cutting state of a dam bar, and is an enlarged view of a portion B of FIG.

FIG. 6 is a diagram showing an arrangement of photosensitive surfaces of a photosensor in the photodetector.

FIG. 7 is a time chart showing signal processing from detection of the arrangement state of leads to oscillation of pulsed laser light.

FIG. 8 is a diagram illustrating a configuration of a delay circuit.

FIG. 9 is a diagram illustrating an example of a moving locus of a processing nozzle, that is, a laser optical axis when cutting all dam bars of a semiconductor device.

FIG. 10 is a diagram showing a state in which three semiconductor devices are integrated and a plurality of integrated semiconductor devices are fixed to a holder;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Work (semiconductor device) 2 Lead frame 3 Lead (web part) 4 Resin mold 5 Dam bar 6 Slit part 7a-7d Reference hole 10 Laser oscillator 10A Pulsed laser beam 11 Beam shape changer 11a Convex cylindrical lens 11b Concave cylindrical lens 11A Pulse laser beam 12 Processing head 13 Processing nozzle 13a Opening 13A (of processing nozzle 13) Pulse laser beam 13B Spot (of pulse laser beam 13A) 13C Laser optical axis 14 Bending mirror 16 Condensing lens 17 Assist gas supply port 17A Assist gas Reference Signs List 18 rotation mechanism 21 processing table 22 X table 23 Y table 24 θ table 30 control circuit 31 detection signal amplifier 32 level discriminator (comparing means) 33 lead frame shape discriminator 34 delay A circuit (delay means) 34a First integration counter 34b Subtraction counter 34c First hold circuit 34d Second integration counter 34e Second hold circuit 35 Laser power supply circuit 36 Beam control unit 37 Light source power supply 38 Table control unit 41 Detection light source 41A Detection Light 41B Irradiation range (of detection light 41A) 42 Photodetector 42A Detection light 43 Bandpass filter 44 Detection lens 45 Photosensor 45a Detection element 100 Holder 101-103 Semiconductor device β (between laser optical axis 13C and detection light 42A ) Inclination angle P Detected position by the photodetector 42 K Focusing position of the pulse laser beam 13A on the work 1 ΔL Preceding distance between P and K

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Minomoto 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Engineering Co., Ltd. (56) References JP-A-2-217186 (JP, A) JP-A-4 −322454 (JP, A) Japanese Utility Model 3-63952 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23/50 B23K 26/00-26/18

Claims (8)

(57) [Claims] 1. A laser oscillator for oscillating pulse laser light, a processing optical system for guiding the pulse laser light to a processing position of a workpiece, and a laser light for emitting the pulse laser light guided by the processing optical system. A processing nozzle provided at an end with an opening for injecting an assist gas, and a conveying means for moving an optical axis of the pulsed laser light relatively at a predetermined speed with respect to the workpiece, and a resin molded semiconductor A semiconductor device in which a chip is sealed on a lead frame is placed on the transport means, and the dam bar of the lead frame is irradiated with the pulse laser beam to sequentially cut the dam bar. At a position on the lead frame that precedes the optical axis of the laser light, a direction opposite to the processing progress direction with respect to the optical axis of the pulsed laser light A detection light generating means for irradiating the detection light so as to reflect in a direction inclined to the detection nozzle; and a detection light which is attached to the processing nozzle and which is incident on the detection light reflected on the lead frame and passed through the opening of the processing nozzle. A light detection unit that generates a detection signal; and a timing for irradiating the pulse laser light based on the detection signal from the light detection unit; and controlling the laser oscillator so that the pulse laser light is irradiated to the center of the dam bar. A dam bar processing apparatus, comprising: 2. The dam bar processing apparatus according to claim 1, wherein the control means binarizes the detection signal to generate a rectangular wave signal, and the center of the dam bar is irradiated with the pulsed laser beam. And a delay means for providing the rectangular wave signal with a delay time corresponding to the width of each dam bar. 3. The dam bar processing apparatus according to claim 2, wherein a position at which the detection light is radiated by the detection light generating means is at least a width of a lead gap near the dam bar with respect to an optical axis of the pulsed laser light. A dam bar processing device which is characterized by being ahead. 4. The dam bar processing apparatus according to claim 1, wherein the pulse laser light oscillated from the laser oscillator is converted into an elongated cross-sectional shape, and the pulse laser light cross-section is formed around the optical axis. A beam shape changing means for rotationally displacing the beam bar. 5. The dam bar processing device according to claim 1, wherein said light detecting means comprises a plurality of detecting elements, and said detecting elements are longer than a width of said dam bar. A dam bar processing device, which is arranged so as to be able to detect a range of a dam bar. 6. A dam bar processing apparatus according to claim 5, wherein said detection light generating means generates a detection laser beam having an elongated cross-sectional shape, and said detection laser beam cross section has a longitudinal dimension. A dam bar processing device characterized by being longer than the width of the dam bar. 7. A method of irradiating a pulse laser beam to a dam bar of a semiconductor device in which a semiconductor chip is sealed on a lead frame with a resin mold and moving an optical axis of the pulse laser beam relative to the semiconductor device at a predetermined speed. In the dam bar processing method of sequentially cutting the dam bar, by moving the dam bar to a position on the lead frame preceding the optical axis of the pulsed laser light applied to the dam bar, the optical axis of the pulsed laser light The detection light is irradiated so as to be reflected in a direction inclined to the opposite side to the processing progress direction, and the detection light reflected on the lead frame and passed through the opening of the processing nozzle is incident to generate a corresponding detection signal, The timing of irradiating the pulse laser beam is determined based on the detection signal, and the pulse laser is positioned at the center of the dam bar at that timing. Dam bar machining method characterized by but controlling the oscillation of the pulse laser beam to be irradiated. 8. The dam bar processing method according to claim 7, wherein the pulse laser beam is converted into an elongated cross-sectional shape, and a longitudinal dimension of a spot at an irradiation position of the pulse laser beam is sufficiently longer than a width of the dam bar. A method of processing a dam bar, comprising irradiating the pulse laser beam so that the longitudinal direction of the spot substantially coincides with the longitudinal direction of the lead of the lead frame and the dam bar is inserted in the width direction.