JP3083448B2 - Laser processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and apparatus capable of processing a predetermined processing position at high speed, and more particularly to a laser processing method and apparatus suitable for processing a lead frame of an IC package.

[0002]

2. Description of the Related Art Conventionally, thin metal plates such as lead frames and metal masks have been processed by pressing or etching. Recently, however, it has been required to finely process the lead frames and metal masks. Therefore, the above-described press and etching cannot respond to the miniaturization. For this reason, attempts have been made to utilize the characteristics of laser light to perform fine processing using the characteristics.
This attempt is disclosed in Japanese Patent Application Laid-Open No. 2-247089. For example, when a lead frame as shown in FIG. 5 is processed, a relatively large pattern of the outer leads 104 and the outer parts of the inner leads 103 are formed. Since processing can be performed by conventional pressing or etching, processing by laser light (hereinafter, referred to as laser processing) is applied only to the inner portion of the inner lead 103 which is a fine pattern.

As a laser beam used for such fine processing, a pulse output type laser beam is used instead of a continuous output type laser beam in order to suppress the influence of heat on the periphery of a processed portion. When processing a lead frame with a pulsed laser beam, usually, a workpiece (metal plate) is irradiated with a circular laser beam spot 90 as shown in FIG. Then, by connecting the circular processed portions to form a linear shape, processing is performed so as to extend the slit portion 91 processed by pressing or etching, thereby forming a slit 92 inside the inner lead. That is, the slit part of a predetermined shape is processed in advance by pressing or etching,
Laser processing is performed from point A to point B in FIG. 11 so that the circular spots 90 are sequentially overlapped. From point B to point C, laser light irradiation is stopped and the irradiation position is moved.
Laser processing is performed so that the circular spots 90 are sequentially overlapped again up to the point. Then, the laser processing is repeated along the same processing locus. However, in FIG. 11, the portion where the slit has penetrated is indicated by oblique lines.

In Japanese Patent Application Laid-Open No. 4-37493,
When etching the outer lead and the outer part of the inner lead, the inner lead is also etched to leave a half-etched state that does not penetrate this part, and only the inner part of the inner lead in this half-etched state is subjected to laser processing. Is disclosed. this is,
It is intended to improve the processing efficiency by minimizing the laser processing range with low efficiency. Further, the positioning for laser processing the inner lead inner portion in the half-etched state is performed using a mark formed on the outer peripheral portion of the lead frame at the time of etching. Furthermore, rather than focusing laser light on the inner part of each inner lead to be laser-processed, before or after peeling off the resist film for etching, the entire surface of the plate surface or a wide area is irradiated with laser light. A method of additionally processing the inner lead inner portion is also disclosed.

[0005]

According to the method of performing laser processing so as to extend a slit portion previously processed by pressing or etching, an error from a design value occurs in a process of manufacturing a workpiece. For example, for example, the design lead pitch is constant, but may not always be the same pitch due to thermal strain during etching. As a result,
The slit portion already formed and the slit portion formed by the laser processing are largely displaced, and in the worst case, a situation where a lead is not correctly formed may occur. Even if the processing locus is set in consideration of these errors, the slit portion which has already been formed due to an installation position error when the workpiece is installed on the laser processing table, a positioning error of the processing table, and the like. There is a possibility that the slit part due to the laser processing is shifted.

Further, in the prior art described in Japanese Patent Application Laid-Open No. 4-37493, positioning during laser processing is performed by using marks formed at the time of etching. If attention is paid to the above, an error from the design value may still occur, and the slit formed by the laser processing may be displaced from the already formed slit. Further, according to the method disclosed in the above publication in which the laser light is irradiated from above the resist film over the entire surface of the plate surface or over a wide area without converging the laser light, the above-described problem of the displacement of the slit portion does not occur. However, since the energy of the laser beam is not converged, it takes a long time for processing, and the resist film may be deteriorated to damage the metal plate surface. Furthermore, when laser light is similarly applied to a wide area after removing the resist film, it takes a long time for processing, and it is very difficult to adjust the final product thickness to the design value. In addition, the surface accuracy of the plate surface is deteriorated. Therefore, a method of irradiating the entire surface or a wide area of the plate surface with the laser light without focusing the laser light is not a preferable method.

An object of the present invention is to form a slit portion by laser processing by extending a slit portion already formed by pressing or etching so that the positions of both slit portions are processed with high precision. It is an object of the present invention to provide a laser processing method and apparatus capable of performing the above.

[0008]

According to the present invention, a workpiece is moved to determine a processing position, and a pulsed laser beam emitted from a laser oscillator is supplied to the workpiece. in the laser processing method for processing by irradiating it said previously formed optically detectable prefabricated parts only the processing position of the workpiece, and the detection light in the vicinity of the working position, the detection light From the reflected light
Except for the reflected light from the central part of the work part,
A laser processing method is provided, comprising: detecting the preliminary processing portion based on a change in the amount of reflected light from which reflected light has been removed, and irradiating the processing position with the laser light based on the detection result to perform processing. You.

[0009]

According to another aspect of the present invention, there is provided a laser oscillator for outputting a pulsed laser beam, a processing optical system for guiding the laser beam to a processing position of a workpiece, and In a laser processing apparatus having a transport means for moving a workpiece and determining the processing position,
A detection light source that irradiates a detection light in the vicinity of the processing position, a detection unit that detects a light amount of the reflected light of the detection light and generates a detection signal, Laser processing comprising: removing means for removing a detection signal; and control means for controlling oscillation of the pulsed laser light so that the processing position is irradiated with laser light based on the detection signal from the removing means. An apparatus is provided.

[0011]

In the laser processing method of the present invention configured as described above, a pre-processed portion that can be optically detected is formed in advance only at the processing position of the workpiece. When the light is irradiated, the amount of the reflected light of the detection light changes at the boundary of the pre-processed portion, and it is possible to detect the pre-processed portion, that is, information on where to process using the reflected light. . Then, in order to perform processing by irradiating the processing position with laser light based on the detection result,
Processing is performed by reliably irradiating a predetermined processing position with laser light in accordance with information on the surface of the workpiece. In other words, if the pre-processed part is formed so as to extend the slit part already formed by pressing or etching, laser processing is performed by adjusting the positions of both slit parts with high precision according to the position of the pre-processed part. It is possible to do.

When detecting the pre-processed portion using the reflected light of the detection light, the amount of the reflected light rapidly changes near the boundary of the pre-processed portion, so that correct detection can be easily performed. In the vicinity of the center of the portion, the amount of reflected light may be indistinguishable from the amount of reflected light from a portion that has not been pre-processed, and a portion having a large amount of reflected light is a portion that has not been pre-processed. May be erroneously detected. In this case, there is only one
Since it is determined that the two pre-processed portions are separate from each other and the laser beam is radiated based on the detection result, unnecessary laser processing is performed at an incorrect position. In the present invention, from the reflected light of the detection light, by removing the reflected light from the central portion of the pre-processed portion, only a sharp change in the reflected light at the boundary of the pre-processed portion is detected, and based on only the detection result. Then, laser light is irradiated, and laser processing is performed at a predetermined correct position.

[0013] In the laser processing apparatus of the present invention configured as described above, the detection light source irradiates the detection light near the processing position, the detection means detects the amount of reflected light of the detection light, and the control means. By controlling the oscillation of the pulsed laser light at a timing based on the detection signal from the detection means, the laser light can be reliably irradiated to a predetermined processing position according to the information on the surface of the workpiece to be processed. Is performed, and the laser processing method of the present invention as described above can be performed. Further, by removing the detection signal based on the reflected light from the central portion of the processing position, the detection signal based on the reflected light from the central portion of the pre-processed portion is removed by the removing unit, and the detection signal of the pre-processed portion is removed. Only a detection signal based on the reflected light at the boundary is sent to the control means, and a laser beam is irradiated based on the detection signal, and laser processing is performed at a predetermined correct position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing method and apparatus according to one embodiment of the present invention will be described with reference to FIGS. In this embodiment, a lead frame for an IC package having pins at equal intervals is processed.

First, the configuration of the laser processing apparatus of this embodiment will be described. As shown in FIG. 1, a laser processing apparatus according to the present embodiment is equipped with a laser oscillator 10 including a laser head 11 and a laser power supply 13, a processing head 12, and a metal plate 1 as a workpiece. The XY table 21, the laser head 11, and the processing head 12 as transporting means for moving (in the XY plane) are moved vertically (in the Z-axis direction).
Table 22 to be moved to the main controller 23
Control unit 2 having a trigger unit 24
5 are provided. The main controller 23 is XY
The movement of the table 21 in the horizontal plane, the movement of the Z table 22 in the vertical direction, and the oscillation of the laser oscillator 10 are automatically controlled.

The laser power supply 13 includes a stabilized power supply 130,
Capacitor section 131, switch section 132, AC power supply 13
3 and a laser controller 26. In the laser power supply 13, first, the AC current supplied from the AC power supply 133 is supplied to the stabilizing power supply unit 130, changed to DC according to the voltage value instructed by the laser controller 26, and supplied to the capacitor unit 131. Capacitor part 1
The charge supplied to the 31 at the above voltage value is supplied to the excitation lamp 110 provided in the laser head 11 by opening and closing the switch unit 132 according to a trigger signal TP ₂ (described later) from the laser controller 26. The excitation lamp 110 emits light by the pulsed current, thereby exciting the laser medium and emitting a pulsed laser beam.

Further, as shown in FIG.
Inside, a bending mirror 120 and a condenser lens 121 having high reflectivity characteristics with respect to the wavelength of the laser beam are provided, which are the same as the configuration of a conventional laser processing apparatus. In this embodiment, a detection light source 122 that generates laser light as detection light, a collimator lens 123,
Half mirror 124, imaging lens 125, photodetector 12
6 is added.
As the detection light source 122, a laser light source such as a laser diode (semiconductor laser) is used. This detection optical system 127 is basically similar in configuration to the optical system of an optical pickup unit that reads a disk signal of a CD player. ing. It goes without saying that the laser light used as the detection light is different from the laser light for performing the laser processing.

A detection signal from the photodetector 126 is input to a trigger unit 24, and the trigger unit 24 receives a predetermined trigger signal TP according to a command from the main controller 23.
₁ is output to the laser controller 26 in the laser power supply 13. That is, as shown in FIG. 3, the trigger unit 24 includes a comparator 241, a trigger signal generation circuit 242,
A delay circuit 243 is provided.
Is binarized by the comparator 241 at a certain threshold value V _th (see FIG. 8) to generate a rectangular wave signal TP, and the trigger signal generating circuit 242 synchronizes with the falling edge of the rectangular wave signal TP. trigger signal TP ₀ is output. Moreover the trigger signal TP _0, the delay time T _D which is commanded from the main controller 23 in the delay circuit 243 is output to the laser controller 26 as TP ₁ given.

As shown in FIG. 4, the laser controller 26 includes an input / output unit 260, a central processing unit 261, and a trigger circuit 262. Trigger circuit 262
Generates a trigger signal TP ₂ having a pulse width instructed from the main controller 23 to the central processing unit 261 in synchronization with the rise of the trigger signal TP ₁ from the trigger unit 24, and the trigger signal TP ₂ is input to the switch unit 132. Is done. The voltage value of the electric charge supplied to the capacitor unit 131 is input from the input / output unit 260 to the central processing unit 261, and is instructed from the central processing unit 261 to the stable power supply unit 130. Thereafter, pulsed laser light oscillates according to the above-described process.

Returning to FIG. 2, the functions of the processing head 12 and the detection optical system 127 will be described. First, the laser beam 100 oscillated from the laser head 11 is transmitted to a bending mirror 120.
The light is focused by the condenser lens 121 and irradiated on the metal plate 1. At this time, the spot image of the detection light 200 on the surface of the metal plate 1 is formed at the position of the photodetector 126 by combining the condenser lens 121 and the imaging lens 125.

The detection light 200 emitted from the detection light source 122 is collimated by a collimator lens 123,
The bending mirror 1 is reflected by the half mirror 124
The light passes through 20 and is focused on the metal plate 1 by the condenser lens 121 at a minute spot. The detection light 200 reflected on the surface of the metal plate 1 passes through the condenser lens 121, the bending mirror 120, and the half mirror 124, and passes through the imaging lens 1
The information is collected by the photodetector 126 by 25 and the information on the surface of the metal plate 1 is detected as an electric signal. In this embodiment, since a laser light source is used as the detection light source 122, the laser light is used for the collimator lens 123 and the imaging lens 1.
25 makes it possible to narrow the aperture very small, and when detecting information on the surface of the metal plate 1 (the presence / absence of a groove 3 described later), the rise (response) of a signal becomes faster and detection can be performed with high resolution.

Next, an example of a lead frame processed according to this embodiment will be described with reference to FIG. The lead frame shown in FIG. 5 is used for an IC package having leads extending from four directions called QFP. A semiconductor chip (not shown) is provided at the center of the lead frame 101.
Is provided, and a number of inner leads 103 and outer leads 104 continuous with the inner leads 103 are provided so as to surround the die pad 102. These adjacent inner leads 103 and outer leads 104 are supported by a dam bar 105 so as to be connected to each other. In addition, the periphery of the die pad 102 except for the arm 102a has a penetrating portion 106.
The inner leads 103 are separated from the die pad 102 by the penetrating portions 106, and the adjacent inner leads 103 are separated by the penetrating portions 106, respectively. Furthermore, the terminals of the semiconductor chip and the inner leads 103 are provided on the outer peripheral portion of the lead frame 101.
A positioning hole 107 is provided for positioning at the time of connection with the device. The dam bar 105 has a role of blocking the resin when molding the semiconductor chip and a role of reinforcing the inner lead 103 and the outer lead 104, and is removed after the molding.

The inner lead 103 extends so as to converge toward the die pad 102, and has a tip portion connected to an electrical connection such as wire bonding performed after a semiconductor chip (not shown) is mounted on the die pad 102. Is wide enough to do. Therefore, the gap (slit) between the adjacent inner leads 103 has an extremely fine structure in which the gap at the inner portion is particularly narrower than the plate thickness. This is where cleanliness is severe.

Next, the laser processing method of this embodiment will be described. First, a metal plate as a material is processed by etching. At this time, the outer lead 10 shown in FIG.
4 and slits on the outer portion of the inner lead 103 and other relatively large pattern portions are made to penetrate by etching, and at the same time, a groove, ie, a pre-processed portion, is formed on the inner portion of the inner lead 103 by etching. In any case, it is impossible to form a slit penetrating in the plate thickness direction even when etching is performed on the inner portion of the inner lead 103 which is a fine pattern. A groove that does not penetrate the inner portion of the lead 103 is left as a pre-processed portion, and the above portion is penetrated by laser processing by a method described later.

That is, as shown in FIG. 6A, the opening 7 for the slit on the outer part of the outer lead 104 and the inner lead 103 and the groove part on the inner part of the inner lead 103 are formed in the resist film 6 for etching. Opening 8 is formed in advance. At this time, the width of the opening 8 is
Make the width sufficiently narrower than that. The openings 7 and 8 may be formed by using a conventional photoresist method.

By performing etching in this state, the metal plate in the portion of the wide opening 7 penetrates in the plate thickness direction to form the slit 2, and in the narrow opening 8, the metal plate penetrates in the plate thickness direction. Without this, it becomes the groove 3. However, in this case,
Since the slit 2 and the groove 3 are simultaneously processed in the same etching step, the positions of the slit 2 and the groove 3 can be matched with high precision without shifting. However, FIG. 6B is a cross-sectional view of the portion of the slit 2 as viewed from the BB direction of FIG. 6A, and FIG. 6C is a view of the portion of the groove 3 as viewed from the CC direction of FIG. It is sectional drawing. In the case of a lead frame having a fine structure, the inner lead 10
Since the width of the opening of the resist film must be narrowed in the inner portion of the resist film 3, it is impossible to penetrate it by etching anymore, and only the groove as shown in FIG. become.

Next, a procedure for penetrating the groove 3 formed as a pre-processed portion as described above by etching by laser processing will be described. First, the metal plate 1 on which the slits 2 and the groove portions 3 are formed is moved by an XY table 21 in a fixed direction and at a constant speed.
The detection light focused on the minute spot from 22 is moved across the groove 3 along the locus 5 on the metal plate 1 shown in FIG. At this time, the change in the detection signal detected by the photodetector 126 is high in the non-groove portion 4 and low in the groove portion 3 as shown in FIG. In particular, near the boundary between the non-groove portion 4 and the groove portion 3, the amount of reflected light changes rapidly, and the detection signal changes sharply. If the non-groove portions 4 and the groove portions 3 of the metal plate 1 are arranged at equal pitches as shown in FIG. 7, the detection signal is detected as a waveform having a constant period as the XY table moves at a constant speed. On the other hand, when the non-groove portions 4 and the groove portions 3 of the metal plate 1 are not arranged at the same pitch, the detection signal is detected as a waveform having a time change proportional to a change in the pitch. However, in FIG. 7, the groove portion 3 is indicated by oblique lines (hereinafter, FIGS. 8 and 1).
The same applies to 0).

Next, this detection signal is transmitted to the trigger unit 24.
And is binarized by a process as shown in the time chart of FIG. However, in FIG. 8, the non-groove portions 4 and the groove portions 3 when the metal plate 1 is moved at a constant speed are schematically added as time changes. The detection signal input from the photodetector 126 to the comparator 241 of the trigger unit 24 is binarized based on a predetermined threshold value V _th indicated by a broken line in the drawing to become a rectangular wave signal TP, and the trigger signal generation circuit 242. The trigger signal generation circuit 242 outputs a trigger signal TP ₀ based on the fall of the rectangular wave signal TP, and the trigger signal TP ₀ is input to the delay circuit 243. The delay circuit 243, the delay time T _D which is commanded from the main controller 23 to the trigger signal TP ₀ is input to the laser configuration torus 26 as a trigger signal TP ₁ given.

Next, the trigger signal TP ₁ in the laser controller 26 is input to the trigger circuit 262, from the trigger circuit 262, the trigger signal TP ₂ in synchronization with the rising edge of the trigger signal TP ₁ is output. Trigger signal TP ₂
Is instructed from the main controller 23 via the central processing unit 261 as described above. Further, the trigger signal TP ₂ is input to the switch section 132, the switch section 132 is closed in synchronization with the rising of the trigger signal TP ₂ , the electric charge from the capacitor section 131 is supplied to the excitation lamp 110, and the trigger signal TP ₂ is further raised. The switch unit 132 opens in synchronization with the fall, and the supply of the charge to the excitation lamp 110 stops. As described above, the trigger signal T
Pulsed laser beam in synchronization with the P ₂ oscillates. In addition,
Trigger signal TP ₂ and the laser light in the drawing has a pulse waveform having a certain fact to the width, in order very pulse width is shorter than the other signals, in the figure is shown in a line.

Here, the delay time T _D given by the delay circuit 243 will be described. Delay in the trigger circuit 262,
Delay of the switch unit 132, and a delay time obtained by integrating the delay until laser oscillation and [delta] _t, further the movement speed of the metal plate 1 v, if the width of the groove 3 of the metal plate 1 and W _s, the machining position Time T to move from end to center of slit 3
₁ is given by T ₁ = W _s / 2v (1). The time T ₂ from when the processing position enters the groove 3 to when the metal plate 1 is irradiated with the laser beam is calculated by using the delay time T _D given by the delay circuit 243 as T ₂ = δ _t + T _D. (2) is represented.

The condition for irradiating the center of the dam bar portion with the laser beam is as follows: T ₁ = T ₂ ... (3) Therefore, from equations (1) to (3), the delay time T _D is given by T _D = W _s / _{2v-δ t} ... it would be set to (4).

[0032] The main controller 23, the locus of scanning the spot of the detection light, the moving velocity v of the XY table 21, the width W _s of the groove 3 of the metal plate 1, the delay time [delta] _t and the pulse width of the trigger signal TP _2, etc. Is input in advance. And
After the above setting, when the XY table 21 is moved at a constant speed v, the pitch of the groove 3 and the moving speed v of the table 21 are changed.
The laser light oscillates at a period determined by the following formula, and irradiation of the laser light is performed at the center of the groove 3, and the groove 3 penetrates by laser processing. Therefore, in a short time of about the oscillation cycle of the laser light,
Performs reliable and high-speed processing. After one scan,
The next scan is performed along a locus slightly shifted in the longitudinal direction of each slit, that is, an operation of processing the groove 3 as shown in FIG. 7 is performed. Further, the scanning is repeated in order to extend the slit already formed by the laser processing, and the inner part of the inner lead 103 is formed in a linear shape.

According to the present embodiment as described above, the outer leads 104 and the inner leads 103 are formed by etching.
When processing the outer portion and the like, the groove 3 that does not penetrate into the inner portion of the inner lead 103 is formed as a pre-processed portion, so that the reflected light of the detection light from the photodetector 126 irradiated near the processing position is used. The groove 3 to be processed can be detected. In addition, since the slit 2 and the groove 3 on the outer lead 104 and the inner lead 103 outer portion are simultaneously processed in the same etching step, the positions of the slits 2 and the grooves 3 can be matched with high precision without being shifted.

In addition, a laser beam is oscillated by signal processing in the trigger unit 24 and the laser controller 26 based on the detection signal detected by the photodetector 126. Can be processed by irradiating the processing position (the center of the slit portion 3 when the pins are at equal intervals) with laser light.
Therefore, the center of the groove 3 can be cut with extremely high positioning accuracy.

Further, the dam bar portion can be cut in a short period of time about the oscillation period of the laser beam determined by the pitch of the slit portion 3 and the moving speed v of the XY table 21, and reliable and high-speed processing can be performed. Further, since the laser beam is applied to a position separated by a certain distance from the end of the web portion 4, a troublesome processing locus for correction is created not only when the pins are at equal intervals but also when they are not at equal intervals. A predetermined position to be cut can be processed reliably and at high speed according to the shape of the metal plate 1 without the need.

Next, a laser processing method and apparatus according to another embodiment of the present invention will be described with reference to FIGS.

When the detection light from the detection light source 122 is irradiated on the metal plate 1 as shown in FIG. 7 and scanning is performed, the amount of reflected light of the detection light at the center of the groove 3 in the width direction is reflected by the bottom of the groove 3. It tends to be relatively large. When detecting the reflected light by the light detector 126 as described above, when the amount of reflected light from the groove portion 3 bottom as shown in FIG. 7 is small compared to the amount of reflected light from the non-groove portion 4, the threshold V _th The difference between the two may be set, but if the difference between the two is small, the waveform of the detection signal based on the light reflected from the bottom of the groove 3 may be higher than the threshold value V _th. When binarized, the waveform of the rectangular wave signal TP is a waveform in which the waveform due to the difference between the non-groove portion 4 and the groove portion 3 and the waveform due to the reflected light from the bottom surface of the groove portion 3 are superimposed (see FIG. 10).

In this case, the groove 3 which is a pre-processed portion is 1
It is determined (erroneous detection) that two grooves are separate even though there is only one. In this embodiment, a gate circuit 245 and a gate signal generator 244 are additionally provided in the trigger unit 24a as shown in FIG. 9 in order to correct such an erroneously detected result. As shown, the portion based on the reflected light from the bottom of the groove 3 is removed from the rectangular wave signal TP.

That is, in the trigger unit 24a, the rectangular wave signal TP generated by the comparator 241 is input to the gate circuit 245, and the gate signal generator 244
Is also entered. From the gate signal generator 244 is a gate signal GP of the predetermined gate width t _g2 as non groove portion 4 receives the falling edge of the waveform due shown in Fig. 10 after a predetermined set time t _g1 of the rectangular wave signal TP It is generated and input to the gate circuit 245. In the gate circuit 245 is AND of the rectangular wave signal TP and the gate signal GP is taken, is inputted to the trigger signal generating circuit 242 as a rectangular-wave signal TP _G.
Thus, when the gate signal GP from the gate signal generator 244 is ON (= 1), a signal having the same waveform as the rectangular signal TP is output from the gate circuit 245,
When the gate signal GP is OFF (= 0), no signal is output. In other words, the portion based on the reflected light from the groove part 3 bottom than the rectangular wave signal TP is removed, the square wave signal TP _G from the gate circuit 245 is accompanied by a sharp change in the reflected light at the boundary of the non-groove portion 4 and the groove 3 Waveform only.

[0040] The square wave signal TP _G is inputted to the trigger signal generating circuit 242, the trigger signal TP ₀ are output on the basis of the fall of the rectangular wave signal TP _G in the trigger signal generating circuit 242, the trigger signal TP ₀ Is input to the delay circuit 243. Then, T commanded delay time T _D from the main controller 23 is given by the delay circuit 243
It is output as P ₁ to the laser controller 26. Thereafter, similarly to FIG. 8, the trigger signal T in the laser controller 26 is synchronized with the rising edge of the trigger signal TP ₁
P ₂ is output, and the trigger signal TP ₂
Is input to the 2, pulsed laser light synchronized with the trigger signal TP ₂ to oscillate.

In the above description, the gate width t _g2 of the gate signal GP may be set so as to satisfy, for example, W _s / v> t _g2 > t _rf (5) Here, _trf is the length of the portion of the waveform of the rectangular wave signal TP based on the reflected light from the bottom surface of the groove 3 (see FIG. 10).

If the trigger unit 24 is not provided with the gate circuit 245 and the gate signal generator 244, the rectangular wave signal TP output from the comparator 241 has a waveform based on the light reflected from the bottom of the groove 3. Is input to the trigger signal generation circuit 242 with the trigger signal TP ₀ being output from the trigger signal generation circuit 242, and the pulse signal based on the light reflected from the bottom surface of the groove 3 by the subsequent signal processing. Will also oscillate. As a result, the laser light is unnecessarily irradiated not only at the center of the target groove 3 but also at an erroneous position other than the groove 3, and predetermined laser processing cannot be realized.

In the present embodiment, the rectangular wave signal TP from the comparator 241 is also input to the gate signal generator 244, and a gate signal GP having a predetermined gate width is generated a predetermined time after its fall, and the gate signal GP is generated. Since the waveform based on the reflected light from the bottom of the groove 3 is removed in the gate circuit 245 based on the signal GP, only a sharp change in the reflected light at the boundary between the non-groove 4 and the groove 3 is taken out, and the subsequent signal processing is performed. This is performed, and only a pulsed laser beam based on this is oscillated. Therefore, a predetermined processing position is reliably irradiated with laser light in accordance with information on the surface of the metal plate 1 to perform processing, and a laser beam is unnecessarily irradiated to an incorrect position other than the predetermined processing position. There is no.

The comparator 241 also outputs the non-groove portion 4
And the waveform based on the boundary of the groove 3 and the waveform based on the light reflected from the bottom of the groove 3 are output alternately. Therefore, in order to remove the waveform based on the light reflected from the bottom of the groove 3, the gate signal as described above is used. An appropriate CPU is provided in place of the generator 244 and the gate circuit 245, and the rectangular wave signal TP output from the comparator 241 is supplied to the rectangular wave signal T every two pulses.
P may be input to the trigger signal generation circuit 242 and processed in a software manner so as to delete other signals.

According to the present embodiment as described above, not only the same effects as in the above-described embodiment can be obtained, but also the gate signal generator 2 can be obtained from the rectangular wave signal TP from the comparator 241.
Since the waveform based on the reflected light from the bottom of the groove 3 is removed by the gate circuit 44 and the gate circuit 245, a predetermined processing position is reliably irradiated with laser light in accordance with information on the surface of the metal plate 1, and processing is performed. The laser beam is not unnecessarily irradiated to an incorrect position other than the processing position.

The groove, which is a pre-processed portion, may not be formed on both surfaces of the metal plate as shown in FIG. 6, but may be formed only on one surface, that is, only on the surface irradiated with laser light. Also, the slits and the like on the outer lead and inner lead outer portions can be processed by pressing instead of etching. Further, illumination light or the like may be used as the detection light source 122 without using a laser light source.

Instead of forming a groove as a pre-processed portion as in the above two embodiments, a coating film or a metal having a reflectance different from that of the base metal plate is applied or plated and etched. Alternatively, after processing the outer lead, the inner lead outer portion, and the like by pressing, the pre-processed portion may be distinguished and detected using the difference in reflectance, and laser processing may be performed.

[0048]

According to the present invention, an optically detectable preliminary processing portion is formed in advance only at the processing position of the workpiece, so that the reflected light of the detection light irradiated near the processing position is used. A pre-processed portion to be processed can be detected.
The laser beam is irradiated to the processing position based on the detection result to perform the processing, so that the predetermined processing position can be reliably laser-processed according to the information on the surface of the workpiece. Therefore, if the pre-processed part is formed so as to extend the slit part already formed by pressing or etching, it is possible to process the slit part by pressing or etching and the slit part by laser processing with high precision. Can be.

Further, since the reflected light from the central portion of the pre-processed portion is excluded from the reflected light of the detection light, the laser beam is radiated based only on the reflected light at the boundary of the pre-processed portion, and the laser beam is irradiated to a predetermined correct position. Laser processing can be performed.

In addition, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals, laser processing can be performed at a predetermined correct position without creating a troublesome processing locus for correction.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a configuration of a laser processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a configuration of a processing head and a detection optical system of FIG. 1;

FIG. 3 is a diagram illustrating a configuration of a trigger unit in FIG. 1;

FIG. 4 is a diagram illustrating a configuration of a laser controller of FIG. 1;

FIG. 5 is a view showing an example of a lead frame processed by the laser processing apparatus of FIG. 1;

FIG. 6 is a view for explaining a situation in which a slit is formed in an outer portion of an outer lead or an inner lead on a metal plate by etching, and a groove (preliminarily processed portion) is formed in an inner portion of the inner lead at the same time. Plan view, (b)
(A) is a sectional view from the BB direction, (c) is CC in (a).
It is sectional drawing from a direction.

FIG. 7 is a diagram illustrating a correspondence relationship between a groove formed in a metal plate and a detection signal from a photodetector.

FIG. 8 is a time chart from output of a detection signal from a photodetector to oscillation of laser light.

FIG. 9 is a view showing a configuration of a trigger unit of a laser processing apparatus according to another embodiment of the present invention.

FIG. 10 is a time chart from output of a detection signal from a photodetector to oscillation of laser light in the embodiment of FIG. 9;

FIG. 11 is a view for explaining a conventional laser processing method in which outer portions of outer leads and inner leads are processed by pressing or etching, and laser processing is performed only on inner portions of inner leads.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Metal plate 2 Slit 3 Groove part 4 Non-groove part 5 Trace 10 Laser oscillator 11 Laser head 12 Processing head 13 Laser power supply 21 XY table 23 Main controller 24 Trigger unit 24a Trigger unit 25 Control unit 26 Laser controller 101 Lead frame 103 Inner lead 104 Outer Lead 120 Bending mirror 121 Condensing lens 122 Detection light source 126 Photodetector 127 Detection optical system 241 Comparator 242 Trigger signal generation circuit 243 Delay circuit 244 Gate signal generator 245 Gate circuit 262 Trigger circuit TP Square wave signal GP Gate signal TP _G rectangle wave signal TP _1, TP ₂ trigger signal

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinya Okumura 650 Kandate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Within the Tsuchiura Plant (72) Inventor: Shigeyuki Sakurai 650, Kandamachi, Tsuchiura City, Ibaraki Prefecture Within the Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. 56) References JP-A-5-277765 (JP, A) JP-A-1-316463 (JP, A) JP-A-4-37493 (JP, A) (58) Fields studied (Int. Cl. ⁷ , (DB name) B23K 26/00-26/42 H01L 23/50

Claims (2)

(57) [Claims] A work position is determined by moving a workpiece,
In a laser processing method for processing by irradiating a pulsed laser beam emitted from a laser oscillator onto the workpiece, an optically detectable preliminary processing portion is formed in advance only at a processing position of the workpiece. Irradiating a detection light in the vicinity of the processing position, and calculating the preliminary processing portion from reflected light of the detection light.
Except for the reflected light from the central part of the
A laser processing method comprising: detecting the preliminary processing portion based on a change in the amount of reflected light from which the light is removed, and irradiating the processing position with the laser beam based on the detection result to perform the processing. 2. A laser oscillator for outputting a pulsed laser light, a processing optical system for guiding the laser light to a processing position of a workpiece, and a transport for moving the workpiece and determining the processing position. A laser processing apparatus comprising: a detection light source that irradiates a detection light in the vicinity of the processing position; a detection unit that detects a light amount of reflected light of the detection light to generate a detection signal; Control means for controlling the oscillation of the pulsed laser light so that the processing position is irradiated with laser light based on the detection signal from the removing means, and removing means for removing the detection signal due to the reflected light from the center of the processing position. A laser processing apparatus comprising: