JPH09314363A - Laser processing apparatus and laser processing method - Google Patents

Abstract

(57) [PROBLEMS] To provide a laser processing apparatus and a laser processing method capable of always detecting a processing position with high accuracy, and performing processing at a desired processing position with high positioning accuracy and at high speed. . A nozzle for irradiating a laser beam from a tip is provided.
The detection sensor 51 is fixed to the sensor 1, and the detection sensor 51 generates a steady magnetic field φ so that the magnetic flux φ penetrates the work 1. Then, the detecting sensor 51 detects the induced current corresponding to the change of the magnetic flux φ based on the presence or absence of the lead portion 104. Based on this induced current (detection signal), the trigger unit 24 generates a trigger signal TP ₁ given a predetermined delay time T _d , and the laser controller 26 further generates a trigger signal T 1.
Generate a trigger signal TP ₂ synchronized with the rising edge of P ₁ ,
Laser light is oscillated based on this trigger signal TP ₂ .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus suitable for removing a dam bar portion of an IC package and capable of processing a desired processing position at high speed.

[0002]

2. Description of the Related Art Processing using pulsed laser light includes processing methods such as cutting, drilling, and welding.
It is used in manufacturing processes in various fields such as semiconductor devices. An example of a conventional laser processing apparatus will be described with reference to FIGS. 7 and 8.

As shown in an example of FIG. 7, a conventional laser processing apparatus has a laser oscillator 30 including a laser head 31 and a laser power source 33, a processing optical system 32, and a work 40 which is a workpiece. In horizontal plane (in XY plane)
To move the XY table 41, the laser head 31, and the processing optical system 32 that are movable in the vertical direction (the Z-axis direction).
A main controller 43 is provided for automatically or manually controlling the movement of the table 42 and the XY table 41 in the horizontal plane, the movement of the Z table 42 in the vertical direction, and the oscillation of the laser oscillator 30.

The laser power supply 33 includes a laser controller 33a, an AC power supply 33b, a stabilized power supply 33c,
It comprises a capacitor section 33d and a switch section 33e. According to the voltage value instructed from the laser controller 33a, the AC current supplied from the AC power supply unit 33b is changed to DC by the stabilized power supply unit 33b, supplied to the capacitor unit 33d, and the electric charge stored in the capacitor unit 33d is switched. The discharge is discharged to the excitation lamp 31a of the laser head 31 based on a predetermined opening / closing timing of the section 33e. The opening and closing of the switch 33e is performed by the laser controller 33a.
From the trigger signal for commanding the pulse width and pulse frequency. Then, a pulsed laser beam oscillates from a laser medium (not shown) in the laser head 31 excited by the excitation lamp 31a.

The laser head 31 has a built-in beam shutter 31b.
Opens / closes to turn on / off pulsed laser light
FF is performed to control the irradiation of the work 40 with laser light. That is, when processing the work 40, the beam shutter 3 is used.
1b is opened, and the beam shutter 3
Close 1b. The opening / closing operation time of the beam shutter 31b is about 100 to 300 msec. The control is performed by the laser controller 33a described above, but it can also be performed by the main controller 43 via the laser controller 33a.

A case in which, for example, a dam bar portion of an IC package is removed (cut) by using the above-described laser processing apparatus will be described. FIG. 8A is a plan view of an IC package (semiconductor device) as the work 40, and FIG.
FIG. 9 is an enlarged view of a B part in FIG. As shown in FIGS. 8A and 8B, the dam bar portion 102 connects the lead portion 104 of the lead frame 101a used for the IC, and when the IC is molded, that is, the resin mold 101.
It has a role of blocking the resin that flows out at the time of the integral sealing by and a role of reinforcing the lead portion 104 of the lead frame 101a, and is a portion that is removed at the end of the manufacturing process. The processing procedure for removing the dam bar portion 102 with a pulsed laser beam will be described by taking as an example the case where the removal (cutting) of the K point in FIG. 8B is completed and the L point is subsequently removed. become that way.

(1) Work 4
The laser beam irradiation position on 0 is moved in the direction from point K to point L in FIG. 8B (the positive direction of the X axis). However, the X axis and the Y axis are defined as shown in FIG. (2) Positioning is performed at point L, and the XY table 41 is stopped. (3) Open the beam shutter 31b. (4) Irradiate the laser beam to remove the dam bar portion 102 at the point L. (5) Close the beam shutter 31b.

By repeating the processing steps (1) to (5) above, the dam bar portions 102 on the four sides of the IC package shown in FIG. 8A are sequentially removed. At this time, the movement and stop of the XY table 41 and the opening and closing of the beam shutter 31b are executed according to a program input to the main controller 43 in advance. During this time, the laser light always oscillates in a pulse shape or oscillates in synchronization with the opening of the beam shutter 31b, and these controls are performed by the above-described laser controller 33a.

Further, as a prior art relating to a laser processing apparatus or a laser processing method suitable for removing the dam bar as described above, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 6-142968. According to this conventional technique, a detection unit that detects the presence or absence of a workpiece near a processing position with a detection light and generates a corresponding detection signal, and a square wave signal generation unit that generates a square wave signal based on the detection signal A laser processing apparatus having control means for controlling the oscillation of the pulsed laser light so that the pulsed laser light is irradiated at a timing based on the rectangular wave signal, only when the processing positions are at equal intervals. However, even if the intervals are not equal, a desired processing position can be processed at a high speed.

[0010]

The size of the dam bar portion of a normal IC package is about 0.1 to 0.3 mm in width and about 0.15 mm in thickness. Can be sufficiently removed by one pulse. Therefore, the time required for the actual processing corresponds to the pulse width of the pulsed laser light, which is about 0.1 to 1 msec. However, in the processing steps (1) to (5) described above, the opening / closing operation time of the beam shutter 31b is 2
It takes 1 s to remove one dam bar part 102 depending on 00 to 600 msec and the moving time of the XY table 41.
It takes a long time of about ec, and if the number of cut dam bars 102 and the number of manufactured IC packages are taken into consideration, it takes too much processing time.

In general, the pitch of the lead portions 104 of the lead frame 101a is often the same. However, there is a manufacturing error of the lead frame 101a, a distortion due to a temperature history when molding with resin, and an external force due to handling. When the dam bar portion 102 is removed, the pitch may not always be equal. The above (1)
In the method (5) for removing the dam bar portion 102, the location where the dam bar portion 102 is removed is registered in the main controller 43 in advance as a program. However, in this method, the lead portions 104 do not have the same pitch. In the worst case where manufacturing errors and deformations are accumulated and the errors increase, there is a possibility that the pins of the lead frame to be left may be damaged.

On the other hand, according to the prior art described in Japanese Patent Application Laid-Open No. 6-142968, a desired processing position can be processed at a high speed not only when the processing positions are at equal intervals but also when they are not at equal intervals. Therefore, even when the pins are not arranged at the same pitch but are arranged irregularly, it is possible to cope with the dam bar removal to some extent. However, the amount of reflected light of the detection light used to detect the presence or absence of the workpiece is greatly influenced by the variation of the amount of light of the detection light source itself or the variation of the amount of reflected light due to the surface condition of the workpiece. In order to obtain positioning accuracy on the order of several microns, such as when removing,
The detection light is required to have a small variation (less than several%) in the amount of light. In addition, positioning accuracy may be deteriorated for a workpiece whose surface reflectivity changes greatly, and some workpieces may not be suitable for actual processing.

Further, a part of the resin or other foreign matter may adhere to the surface of the lead or the dam bar in the lead frame, or the adhered foreign matter may protrude. In such a case, the detection as described above is performed. When the detection is performed by light, the foreign matter may be erroneously detected as if it were a part of the lead. As a result, there is a possibility that the positioning accuracy of the laser beam irradiation is reduced and erroneous irradiation may be performed at a position other than a predetermined position, and there is a possibility that processing with desired dimensions cannot be performed.

An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of always detecting a processing position with high accuracy, and performing processing at a desired processing position with high positioning accuracy and at high speed. That is.

[0015]

In order to achieve the above object, according to the present invention, a laser oscillator that oscillates a pulsed laser beam and a machining optical system that guides the laser beam to a machining position of a workpiece. A laser processing apparatus comprising: a moving means for moving the workpiece and determining a processing position thereof; a magnetic field generating means for generating a steady magnetic field to penetrate the magnetic flux into the workpiece; Detecting means for detecting a change in the magnetic field depending on the presence or absence of the workpiece at the position and generating a detection signal corresponding to the change in the magnetic field, and a predetermined processing position of the workpiece based on the detection signal from the detecting means. There is provided a laser processing apparatus comprising: a control unit that controls oscillation of the laser light so that the laser light is irradiated.

In order to achieve the above object, according to the present invention, the workpiece is moved to determine the processing position, and a pulsed laser beam is emitted from the laser oscillator to the processing position to perform the processing. In the laser processing method for processing objects,
Generate a steady magnetic field and let the magnetic flux penetrate the work piece, detect the change in the magnetic field depending on the presence or absence of the work piece at the processing position, and at a timing based on the detection signal corresponding to the change in the magnetic field. A laser processing method is provided, which comprises irradiating a predetermined processing position on the workpiece with laser light.

In the present invention configured as described above,
A stationary magnetic field is generated by the magnetic field generating means to cause the magnetic flux to penetrate the work piece, and the work piece is moved in that state. Then, the mutual inductance changes depending on the presence or absence of the work piece at the processing position, thereby changing the magnetic field, that is, the magnetic flux at the processing position. Then, the detection means generates a detection signal corresponding to the change in the magnetic field. At this time, for example, an induced current corresponding to a change in magnetic flux may be detected and a detection signal corresponding thereto may be generated. By using a steady magnetic field in this way and detecting the presence or absence of the work piece at the processing position from the change in the magnetic field due to the change in mutual inductance with the work piece, the detection accuracy is Is not affected by
It becomes possible to detect the presence or absence of the workpiece with high accuracy.
For example, in the case of the dam bar cutting described above, the change in mutual inductance due to the adhesion of a part of resin or other foreign matter is small compared to the change in mutual inductance due to the presence or absence of the work piece, that is, the metal lead. As long as the presence or absence of the work piece at the processing position is detected from the change in the magnetic field due to the change in mutual inductance, there is no effect due to the adhesion of part of the resin or other foreign matter.

After the detection signal from the detection means is generated, the control means controls the oscillation of the laser beam based on the detection signal, so that the presence or absence of the workpiece at the machining position, that is, the surface of the workpiece. According to the information, the desired processing position is surely irradiated with the laser beam to perform the processing. Also,
Since the laser light is irradiated at a position away from the position where the information on the presence or absence of the workpiece is detected by a constant distance, not only when the processing positions are not evenly spaced,
A desired position to be cut is processed surely and at high speed according to the information on the presence or absence of the work piece.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to FIGS. However, the removal of the dam bar of the QFP type IC package in which the leads arranged at equal intervals extend from four sides will be described below.

As shown in FIG. 1, in the laser processing apparatus of this embodiment, a laser oscillator 10 including a laser head 11 and a laser power source 13, a processing head 12, and a workpiece (IC package) as a workpiece. 1. An XY table 21 as a transporting means for carrying 1 and moving it in a horizontal plane (in the XY plane), a Z table 22 for moving the laser head 11 and the processing head 12 in the vertical direction (Z axis direction), a main controller 23 and a trigger unit. A control unit 25 having 24 is provided. The main controller 23 controls the movement of the XY table 21 in the horizontal plane, the movement of the Z table 22 in the vertical direction, and the laser oscillator 1.
The oscillation operation of 0 is automatically controlled. Also, the processing head 1
2 is provided with a nozzle 12a in the lower part, and a detection sensor 51 is attached near the tip of the nozzle 12a (see FIG. 2).
(A)).

The laser power source 13 includes a stabilizing power source 130, a capacitor section 131, a switch section 132, and an AC power source section 13.
3 and a laser controller 26. In the laser power supply 13, first, the AC current supplied from the AC power supply unit 133 is supplied to the stabilizing power supply unit 130, changed to DC according to the voltage value commanded by the laser controller 26, and supplied to the capacitor unit 131. . The electric charge supplied to the capacitor unit 131 at the above-described voltage value is supplied to the excitation provided in the laser head 11 by opening and closing the switch unit 132 with a predetermined pulse width according to a trigger signal TP ₂ (described later) from the laser controller 26. It is supplied to the lamp 110. The excitation lamp 110 emits light by the pulse-like charges, and thereby a laser medium (not shown) in the laser head 11 is excited to emit a pulse-like laser beam.

The beam shutter 11 is attached to the laser head 11.
1 is built-in. The beam shutter 111 turns on / off the pulsed laser light emitted from the laser oscillator 10 by opening and closing, and controls the irradiation of the work 1 with the laser light. That is, when processing the work 1, the beam shutter 111 is opened, and when not processing, the beam shutter 111 is closed. This beam shutter 11
The opening / closing operation time of No. 1 is about 100 to 300 ms. The opening / closing operation of the beam shutter 111 is controlled by the laser controller 26, but can be controlled by the main controller 23 via the laser controller 26.

Inside the processing head 12, a dichroic mirror having a high reflectance characteristic with respect to the wavelength of the laser light, a condenser lens and the like are provided, and the laser light from the laser head 11 is guided in the direction of the work 1. The light is focused and condensed, and the dam bar 102 (see FIG. 5) of the work 1 is irradiated with the light and cut. The above is the same as the configuration of the conventional laser processing apparatus.

The nozzle 12a under the processing head 12
The detection sensor 51 attached to the tip is shown in FIG.
As shown in FIG. 2, the XY table 21 (work 1) is fixed to be perpendicular to the XY table 21 (work 1). Further, the detection sensor 51 is
As shown in FIG. 2B, which is an enlarged view of a portion B of FIG. 2A, a magnet portion 52 formed of a rod-shaped permanent magnet in the center is shown.
And a search coil 5 on the outer circumference of the magnet portion 52.
3 is wound like a solenoid. With such a configuration, the magnetic flux φ is emitted from the magnet portion 52, and if the magnetic flux φ does not change, no current is generated in the search coil 53. However, as will be described later, the presence or absence (arrangement) of leads in the work 1 is determined. Accordingly, when the mutual inductance between the magnet unit 52 and the work 1 changes, the magnetic flux φ
Changes, and an induced current i (calculated as a time derivative of the magnetic flux φ) corresponding to the change in the magnetic flux is generated in the search coil 53. The induced current i is emitted from the detection sensor 51 as a detection signal. The fixed position of the detection sensor 51 is set to a position separated by δd from the center axis of the nozzle 12a, and a position separated by δd from the optical axis and the condensing position of the laser beam for cutting the dam bar is detected. ing.

In the trigger unit 24, as shown in FIG. 3, the detection signal (induction current) i from the detection sensor 51 is amplified in the main amplifier 241, and is converted into the voltage signal S of the same waveform, so that the low-pass signal is passed. Noise is removed by the active low-pass filter circuit 242 of the signal TP
Is generated, and the signal TP is converted into the trigger signal TP ₀ by the trigger signal generation circuit 243 at the timing when the signal TP crosses the zero level (see FIG. 5). Further, the delay circuit 244 delays the command from the main controller 23. The trigger signal TP ₁ is generated by applying the time T _d , and this trigger signal TP ₁ is output to the laser controller 26.

Further, 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 this trigger signal TP ₂ is transmitted to the switch unit 132. Is entered. 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 stabilized power supply unit 130. Thereafter, the laser light oscillates according to the above-described process.

Next, the operation of the laser processing apparatus having the above configuration will be described. FIG. 5 is a time chart from the detection of the presence or absence of the lead by the detection sensor 51 to the oscillation of the laser light. First, the center axis of the nozzle 12a, that is, the optical axis of the laser beam, is positioned on the center line of the dam bar 102 of the IC package, and the position detected by the detection sensor 51 is set at a position away from the dam bar 102 by δd. In FIG. 2, the left side in the drawing is the direction away from the resin mold 101. In this state, the work 1 is moved to the XY table 2
For example, when the nozzle 12a is moved at a constant speed in the negative direction of the X-axis, the nozzle 12a and the detection sensor 51 relatively move with respect to the work, and the center axis (the optical axis of the laser beam) of the nozzle 12a The trajectory of the detection position of the sensor 51 draws a parallel trajectory while maintaining the interval of δd as shown by A and B in FIG. The moving direction of the XY table 21 at this time is as shown in FIG.
Then, the direction becomes closer to the vertical than the paper. In the upper part of FIG. 5, the lead portions 104 and the slit portions 103, which are the gaps between the lead portions 104, along with the loci A and B, are schematically shown as a change with time when the work 1 is moved at a constant speed. In addition, the positional relationship between the resin mold 101 and the dam bar 102 is also shown.

When the detecting sensor 51 moves at a constant speed along the locus B as described above, the magnetic flux φ passing through the search coil 53 changes depending on the presence or absence of the lead portion 104, as shown in FIG. 5, for example. At this time, if the lead portion 104 and the slit portion 103 of the work 1 are arranged at equal pitches, the XY table 21 moves at a constant speed, and thus the magnetic flux change has a constant period as shown in FIG. When the slit portions 103 are not arranged at equal pitches, the magnetic flux change has a waveform having a time change proportional to the pitch change. An induced current i is generated in the search coil 53 in response to this change in magnetic flux, which is amplified by the main amplifier 241 and converted into a voltage signal S having the same waveform, and noise is removed by the active low-pass filter circuit 242 to generate a signal TP. Become.
However, in FIG. 5, since only the change of the current i is a problem, the positive and negative signs are ignored. Further, for simplification, changes in the voltage signal S and the signal TP are collectively represented as a detection signal.

Subsequently, the signal TP is the trigger signal generation circuit 2
43, and the signal TP changes its zero level from + to −
Pulse-shaped trigger signal T based on the timing of crossing over, that is, the timing corresponding to the central portion of the lead portion 104.
P ₀ is generated in the delay circuit 244 the trigger signal TP ₁ and commanded delay time T _d is given from the main controller 23 is generated, the trigger signal TP ₁ is output to the laser controller 26. In particular, in the present embodiment, when the trigger signal TP ₀ is generated from the signal TP, it is based on the timing at which the zero level crosses from + to −, but if the detection position can be specified, other timing is used. It may be the basis.

The trigger signal TP ₁ is input to the trigger circuit 262, and the trigger signal TP ₂ synchronized with the rising edge of the trigger signal TP ₁ is output. The pulse width of the trigger signal TP ₂ is instructed from the main controller 23 as described above through a central portion 261. Trigger signal TP ₂ is input to the switch unit 132, the switch unit 132 is turned ON in synchronization with the rising edge of the trigger signal TP _2, the charge from the capacitor 131 is supplied to the excitation lamp 110,
Further in synchronization with the falling edge of the trigger signal TP _2, next to the switch unit 132 is OFF, the supply of charge to the excitation lamp 110 is stopped. As described above, the trigger signal TP
A pulsed laser light synchronized with ₂ oscillates. In the above description, a certain time is required from the generation of the trigger signal TP ₂ to the laser light oscillation due to the delay in the switch unit 132, the laser oscillation in the laser head 11, and the like. The delay time was set to δ _t . Note that the trigger signal TP ₂ and the laser light in the figure actually have a pulse waveform having a certain width, but since the pulse width is very short compared to other signals, they are shown in a linear manner in the figure. .

Here, the delay time T _d given by the delay circuit 244 will be described. When the moving speed of the work 1 is v and the width of the slit portion 3 of the work 1 is L, the detection sensor 51 detects the central portion of the lead portion 104 (that is, the signal TP changes its zero level from + to −). From the timing of crossing), the time t ₁ during which the optical axis (spot position) of the laser light moves to the center of the slit portion 103 is t ₁ = (L / 2) / v 2 (1). The time t ₂ from when the center of the lead portion 104 is detected to when the laser light is irradiated onto the work 1 is calculated by using the delay time T _d given by the delay circuit 244 as t ₂ = T _d + t _0. ··· (2) Here, t ₀ is a delay time obtained by integrating the delay in the trigger signal circuit 243, the delay time δ _{t in} FIG. 5, and the delay generated in other circuits.

Since the condition for irradiating the center of the dam bar portion 102 with the laser light is t ₁ = t ₂ (3), the delay time T _d can be calculated from the equations (1) to (3) as T _It suffices to set _d = L / (2v) -t ₀ (4). The delay time t ₀ , the moving speed v of the work 1, and the width L of the slit portion 103
Is input to the main controller 23 in advance.

In the above, the case where the dam bar 102 on the side of the IC package shown in FIG. 5 is cut and removed has been mainly described, but subsequently, the dam bars 102 on the remaining three sides of the IC package are sequentially cut, The case of removing will be described with reference to FIG. However, in FIG.
The axis and the Y axis are defined as shown. When the cutting of all the dam bars 102 on the side shown in FIG. 5 (the positive direction of the X axis) is completed,
The nozzle 12a is rotated 90 ° counterclockwise around the central axis of the nozzle 12a. Then, the machining position is moved in the positive direction of the Y axis at a constant speed v by the XY table 21,
Based on the detection signal (along the locus B ₁ ) based on the detection by the detection sensor 51, the dam bar 102 is cut and removed by the laser beam as described above. Next, the nozzle 12a
Is further rotated counterclockwise by 90 °, the machining position is moved in the negative direction of the X-axis at a constant speed v by the XY table 21, and a detection signal (along the locus B ₂ ) based on the detection by the detection sensor 51 is detected. Based on the above, the dam bar 102 is cut and removed by laser light as described above. Next, the nozzle 12a is further rotated counterclockwise by 90 °, and the machining position is moved by the XY table 21 in the negative direction of the Y axis at a constant speed v.
And the dam bar 102 is cut and removed by the laser light as described above based on the detection signal (along the locus B ₃ ) based on the detection by the detection sensor 51. Thus, the cutting and removal of the dam bar 102 on all four sides of the IC package are completed. Further, the positional relationship between the optical axis 100A of the laser beam and the detection position 200A of the detection sensor 51 when the dam bar 102 on each side of the IC package is cut is as shown in each side of FIG. In the above description, the nozzle 12a is rotated counterclockwise when moving to the adjacent side, but the XY table 21 may be rotated clockwise.

According to the present embodiment as described above, a stationary magnetic field is generated by the detection sensor 51 so that the magnetic flux penetrates the workpiece, and the magnetic flux φ changes depending on the presence or absence of the lead portion 104. Since the induced current i is detected, the presence / absence of the lead portion 104 can be detected with high accuracy without being affected by the adhesion of a part of resin or other foreign matter. Then, based on the induced current i, the subsequent trigger unit 2
4 and the laser controller 26 oscillate the laser light by the signal processing, the laser light is emitted to a desired processing position (the center portion of the slit portion 3 when the pins are at equal intervals) according to the information on the surface of the work 1. Can be processed. Also, the pitch of the slit portion 103 and XY
The dam bar portion can be cut in a short time of about the oscillation cycle of the laser light determined by the moving speed v of the table 21, and reliable and high-speed processing is possible. Further, the lead portion 10
Since the laser beam is radiated at a position apart from the four ends by a constant distance, it is desirable to cut according to the shape of the work 1 not only when the lead portions 104 are evenly spaced but also when they are not equally spaced. The position of can be processed reliably and at high speed.

[0035]

According to the present invention, a stationary magnetic field is generated by the magnetic field generating means to cause the magnetic flux to penetrate the workpiece, and the induced current corresponding to the presence or absence of the workpiece at the machining position is detected. The processing position can always be detected with high accuracy without being affected by the adhesion of foreign matter. Further, since the oscillation of the laser light is controlled based on the induced current, it is possible to perform the processing at the desired processing position with high positioning accuracy and high speed according to the information on the surface of the workpiece. further,
Not only when the processing positions are equidistant but also when the processing positions are not equidistant, the predetermined processing positions can be processed reliably and at high speed.

[Brief description of drawings]

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

FIGS. 2A and 2B are views showing a nozzle and a sensor for detection in the laser processing apparatus of FIG. 1, wherein FIG.
[Fig. 3] is an enlarged view of a B portion in (a).

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 time chart from detection of the presence or absence of a lead by the detection sensor to laser light oscillation.

6A and 6B are views for explaining a case where dam bars on four sides of an IC package are sequentially cut and removed by the laser processing apparatus of FIG.

FIG. 7 is a configuration diagram of a conventional laser processing apparatus.

8A and 8B are views for explaining a case where, for example, the dam bar portion of an IC package is removed (cut) by using the laser processing apparatus of FIG. 7, FIG. 8A is a view showing an IC package having a dam bar, FIG. 7B is an enlarged view of a B part in FIG.

[Explanation of symbols]

 1 Work 10 Laser Oscillator 11 Laser Head 12 Processing Head 12a Nozzle 13 Laser Power Supply 21 XY Table 22 Z Table 23 Main Controller 24 Trigger Unit 25 Control Unit 26 Laser Controller 51 Detection Sensor 52 Magnet Part 53 Search Coil 101 Resin Mold 102 Dam Bar Part 103 Slit part 104 Lead part 110 Excitation lamp 130 Stabilized power supply part 131 Capacitor part 132 Switch part 133 AC power supply 241 Main amplifier 242 Active low-pass filter circuit 243 Trigger signal generation circuit 244 Delay circuit 260 Input / output part 261 Central processing part 262 Trigger circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kuroda 650 Jinrachicho, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory

Claims (2)

[Claims] 1. A laser oscillator that oscillates pulsed laser light, a processing optical system that guides the laser light to a processing position of a workpiece, and a conveying unit that moves the workpiece and determines the processing position. In a laser processing apparatus comprising: a magnetic field generating means for generating a steady magnetic field and penetrating the magnetic flux into the workpiece, and detecting a change in the magnetic field depending on the presence or absence of the workpiece at the processing position, A detection unit that generates a detection signal corresponding to a change in the magnetic field, and controls oscillation of the laser beam so that the laser beam is irradiated to a predetermined processing position of the workpiece based on the detection signal from the detection unit. A laser processing apparatus comprising: a control unit. 2. A laser processing method for moving a workpiece to determine a processing position, irradiating a pulsed laser beam from the laser oscillator to the processing position to process the workpiece, and a stationary magnetic field. To cause the magnetic flux to penetrate through the workpiece, detect a change in the magnetic field depending on the presence or absence of the workpiece at the processing position, and process the workpiece at a timing based on a detection signal corresponding to the change in the magnetic field. A laser processing method comprising irradiating a predetermined processing position of an object with the laser light.