JP3113804B2 - Laser processing apparatus, laser processing method, and dam bar processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse laser processing apparatus and a pulse laser processing method capable of processing a desired processing position at a high speed, and further to a dam bar processing method for cutting a dam bar of an IC package.

[0002]

2. Description of the Related Art Processing using pulsed laser light (hereinafter referred to as pulsed laser light) includes cutting, drilling,
Processing methods such as welding are used in manufacturing processes in various fields such as machines, electronics, and semiconductor devices. The configuration of a conventional laser processing apparatus will be described with reference to FIGS.

A conventional pulse laser processing apparatus includes a laser head 31 and a processing optical system 3 as shown in FIG.
2. an XY table 4 on which a laser power source 33 and a workpiece 40 to be processed are mounted and which can be moved in a horizontal plane (XY plane)
1. Movement of the Z table 42 and the XY table 41 in the horizontal plane for moving the laser head 31 and the processing optical system 32 in the vertical direction (Z axis direction), the movement of the Z table 42 in the vertical direction, and oscillation of pulsed laser light A main controller 43 for automatically or manually controlling the operation is provided. The laser head 31 and the laser power supply 33 constitute a laser oscillator 30.

The laser power supply 33 comprises a laser controller (not shown), a stabilized power supply, a capacitor section, a switch section, and the like. According to the voltage value commanded by the laser controller, the supplied AC power is changed to DC by the stabilized power supply, supplied to the capacitor unit, and the electric charge stored in the capacitor unit is opened and closed by the switch unit via the switch unit. The discharge is performed to an excitation lamp (not shown) of the laser head unit based on the timing. The opening and closing of the switch unit is performed in accordance with a trigger signal for instructing a pulse width and a pulse frequency from a laser controller. As described above, the pulse laser light is emitted from the laser head 31.

The laser head 31 has a built-in beam shutter (not shown). The beam shutter is opened and closed to control the irradiation of the work 40 with pulsed laser light. That is, the beam shutter is opened when the workpiece 40 is processed, and the beam shutter is closed when the workpiece 40 is not processed. The opening / closing operation time of the beam shutter is about 100 to 300 msec, and the control is performed by the above-described laser controller. However, the control can also be performed by the main controller 43 via the laser controller.

A case will be described in which, for example, a dam bar of an IC package is removed using the above-described pulse laser processing apparatus. 9A is a plan view of the IC package, and FIG. 9B is an enlarged view of a portion B in FIG. 9A. FIG.
As shown in (b), the dam bar 2 connects the pins (hereinafter, also referred to as leads) of the lead frame used for the IC, and plays a role of damming the resin at the time of molding the IC and reinforcing the pins of the lead frame. This is the part that is removed at the end of the manufacturing process. The processing procedure for removing the dam bar 2 with a pulse laser beam is described in FIG.
Removal (cutting) of the point is completed, and then processing (removal) of point L
The following is an example of performing the above operation.

(1) Work 4
The irradiation position of the pulse laser beam on the zero is moved from the point K in FIG. 9B to the direction of the point L (the direction of the X axis). (2) Positioning is performed at point L, and the XY table 41 is stopped. (3) Open the beam shutter. (4) Irradiating the pulse laser beam to remove the dam bar at the point L. (5) Close the beam shutter. By repeating the processing steps (1) to (5), the dam bars 2 on the four sides of the IC package shown in FIG. 9A are sequentially removed. At this time, the movement and stop of the XY table and the opening and closing of the beam shutter are executed according to a program previously input to the main controller 43. During this time, the pulsed laser light always oscillates in a pulse shape or oscillates in synchronization with the opening of the beam shutter, and these controls are performed by the above-described laser controller.

Conventional techniques relating to a laser processing apparatus or a laser processing method suitable for removing the dam bar as described above are described in, for example, JP-A-56-9090 and JP-A-4-41092. There are things. The former method described in Japanese Patent Application Laid-Open No. 56-9090 discloses a method in which a laser beam is oscillated uniformly in response to a change in a processing speed (moving speed of an XY table), and the latter is disclosed in Japanese Patent Application Laid-Open No. The apparatus described in Japanese Patent Application Laid-Open No. 4-41092 discloses a method of turning on / off a laser beam in accordance with a comparison result between a plurality of pieces of processing position information stored in advance and a movement amount of an XY table.
It controls OFF and irradiation timing.

Further, a laser processing apparatus and a laser processing method capable of processing a desired processing position at a high speed not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals are disclosed in JP-A-6-81876. There is a thing of the description. In this prior art, a detecting means for detecting presence or absence of a workpiece near a processing position and generating a corresponding detection signal, a rectangular wave signal generating means for generating a rectangular wave signal based on the detection signal, There is disclosed a laser processing apparatus including control means for controlling oscillation of pulsed laser light so that the pulsed laser light is irradiated at a timing based on a wave signal.

[0010]

The size of the dam bar of the above IC package is about 0.1 to 0.3 mm in width and 0.1 mm in thickness.
Since it is about 15 mm, a single pulse of laser light can sufficiently remove the dam bar. Therefore, the time required for the actual processing corresponds to the time of the pulse width of the pulse laser light, and is about 0.1 to 1 msec. However, in the processing procedures (1) to (5) described above, the opening and closing operation time of the beam shutter is 200 to 600 msec.
The time required for removing one dam bar is about 1 sec depending on the time required to move one table, and the processing time is too long in consideration of the number of cut dam bars and the number of manufactured IC packages.

In general, the pitch of the pins (leads) is often the same. However, the pins may be deformed due to manufacturing errors of the lead frame, distortion due to temperature history when molding with resin, or external force due to handling. When the dam bar is removed, the pitch may not always be equal. In the dam bar removing method described in the above (1) to (5), the location at which the dam bar is removed is registered in the main controller in advance as a program. I ca n’t respond,
Further, in the worst case where the manufacturing error and deformation are accumulated and the error is increased, there is a possibility that the lead frame portion to be left is damaged.

When the conventional technique described in Japanese Patent Application Laid-Open No. 56-9090 is applied to dam bar removal, the pins are not arranged at regular pitches but irregularly arranged to uniformly irradiate the laser beam. When this happens, it cannot be handled, and the same problem as described above occurs. Further, when the conventional technique described in Japanese Patent Application Laid-Open No. 4-41092 is applied, only control according to a predetermined shape stored (assumed) in advance can be performed.
Again, it is not possible to cope with the case where the pins are arranged irregularly, and the same problem occurs.

On the other hand, according to the prior art disclosed in Japanese Patent Application Laid-Open No. 6-81876, 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, during laser processing, scattered molten matter (spatter) adheres to the lead surface. Therefore, when the conventional technique described in JP-A-6-81876 is applied to dam bar removal, the molten scattered substance (spatter) is detected by the scattered molten matter adhered to the lead surface. The reflected light of the light is scattered, the amount of reflected light from the lead decreases, as if it passed through the edge of the lead,
That is, there is a possibility that a pulse laser beam for processing is erroneously irradiated by erroneously recognizing that it has entered a slit portion where no lead exists.

That is, when the rectangular wave signal is generated by the rectangular wave signal generating means based on the detection signal corresponding to the reflected light of the detection light, the change in the detection signal caused by the molten and scattered matter attached to the lead surface, ie, the detection There is no problem if the decrease in the signal level is larger than the threshold value for generating a square wave signal, but if it is smaller than a predetermined threshold value, the output rectangular wave signal is at the edge of the lead. In addition, the pulsed laser beam is oscillated (erroneously oscillated) even by the erroneously detected rectangular wave signal because it is generated in synchronization with the scattered and scattered matter scattered on the lead surface. . Therefore, there is a problem that erroneous irradiation is performed on an erroneous position other than the predetermined laser processing position, and the laser processing is performed.

An object of the present invention is to enable a high-speed processing of a desired processing position where an object to be processed exists not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals, and the laser processing can be performed at the same time. An object of the present invention is to provide a laser processing apparatus and a laser processing method in which laser processing is not unnecessarily performed based on a melted and scattered substance generated.

[0016]

According to the present invention, there is provided, in accordance with the present invention, a laser oscillator for oscillating a pulsed laser beam based on a trigger signal; In a laser processing apparatus including a processing optical system that guides the workpiece and a transport unit that moves the workpiece and determines the processing position, a detection light for detecting the presence or absence of the workpiece near the processing position is generated. Detection light source, detection means for detecting reflected light of the detection light from near the processing position, and generating a detection signal corresponding to the reflection light, and a trigger for oscillating pulsed laser light.
A gate signal having a gate width for a predetermined period from the generation of a gas signal
Signal from a gate signal generator for generating a signal
The generated detection signal is input, and is output from the gate signal generator.
Occurs during periods other than within the gate width of the generated gate signal
A gate circuit for outputting only the detected detection signal;
Based on the detection signal output from the bets circuit, wherein as said laser beam to a predetermined processing position of the workpiece is irradiated before
Outputs the serial trigger signal, and a control means for controlling the oscillation of the laser beam, when the laser processing of the detected signal
At the processing position
The generated detection signal is deleted, and the
Extracts only the detection signal based on the presence or absence of the workpiece and retrieves it
The laser beam oscillation is controlled based on the detected
Perform the processing.

In the present invention configured as described above,
Detection light for detecting the presence or absence of a workpiece near the processing position is generated from a detection light source, and light from the workpiece is detected by a detection unit, and a detection signal corresponding to the light is generated. At this time, in the detection signal generated from the detection means, in addition to the change according to the presence or absence of the workpiece, the change due to the molten scattered material (sputter) scattered from the processing portion during laser processing and attached near the processing position is also included. Will exist. Therefore, the gate signal generation circuit and the gate circuit, except for the detection signal resulting from the molten debris adhering to the processing position near the time of laser processing of the detection signal, the detection signal based on the presence or absence of the workpiece at the machining position near By taking out only the workpiece and inputting it to the control means, the control means controls the oscillation of the laser beam based only on the detection signal based on the presence or absence of the workpiece, and performs desired processing in accordance with information on the surface of the workpiece. The position is reliably irradiated with laser light to perform processing. Thereby, the laser beam is not oscillated based on the change of the detection signal caused by the scattered melted object, and the laser beam is not unnecessarily irradiated to an erroneous position other than the predetermined processing position. In addition, since the laser beam is applied to a position that is a fixed distance away from the position where the information on the presence or absence of the workpiece is detected, the processing is performed not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals. A desired position to be cut is processed reliably and at high speed in accordance with information on the presence or absence of an object.

According to the present invention, in order to achieve the above-described object, a workpiece is moved to determine a processing position, and
In the laser processing method of processing the workpiece by irradiating the processing position with a pulsed laser beam from a laser oscillator based on a rigger signal, detection for detecting the presence or absence of the workpiece near the processing position is performed. Light is irradiated to the vicinity of the processing position , the reflected light is detected, and the detected reflected light is
Among the corresponding detection signals, a portion from the occurrence of the trigger signal
This gate width of the gate signal having the gate width during the period
Only based on the detection signal generated during the period other than
A predetermined processing position of a workpiece is irradiated with the laser light.
Output the trigger signal to oscillate the laser light
Controlling the laser out of the detection signals corresponding to the reflected light.
Caused by melted splatters attached near the processing position during processing
Delete the detection signal corresponding to the reflected light generated by the
Detection signal based on the presence or absence of the workpiece near the processing position
Laser processing by controlling the oscillation of laser light based only on
Do.

Further, according to the present invention, in order to achieve the above-mentioned object, a dam bar in an IC package in which a semiconductor chip is mounted on a lead frame and is integrally sealed with a resin mold is pulsed based on a trigger signal . in the dam bar machining method of cutting by laser beam irradiation, irradiated with inspection light output to the dam bar near to detect the reflected light, test
Out of the detection signals corresponding to the emitted reflected light,
Signal having a gate width for a predetermined period from the occurrence of a signal
Of the detection signal generated during a period other than within the gate width
On the dam bar at the specified machining position
The trigger signal is output so that the light is irradiated,
Controlling the oscillation of the laser light, and detecting the reflected light.
Signal adhered near the processing position during laser processing
Detection signal corresponding to the reflected light generated by the melted splatter
Number, and the presence or absence of the workpiece near the machining position
Control of laser light oscillation based only on detection signal based on
And perform laser processing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to FIGS. However, in the following, the removal of the dam bar of an IC package having pins at regular intervals will be described.

As shown in FIG. 1, a laser processing apparatus according to the present embodiment includes a laser oscillator 10 including a laser head 11 and a laser power supply 13, a processing head 12, and a workpiece (IC package). 1. An XY table 21 as a transporting means for mounting and moving the laser head 11 in a horizontal plane (XY plane), a Z table 22 for vertically moving the laser head 11 and the processing head 12 (Z-axis direction), a main controller 23, and a trigger unit A control unit 25 having a control unit 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.

The laser power supply 13 includes a stabilizing power supply 130,
It has a capacitor section 131, a switch section 132, 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. The electric charge supplied to the capacitor unit 131 at the above-described voltage value is applied to the laser head 1 by the opening / closing operation of the switch unit 132 according to a predetermined pulse width by a trigger signal TP ₂ (described later) from the laser controller 26.
1 is supplied to the excitation lamp 110 provided in the first embodiment. The excitation lamp 110 emits light by the pulse-like charges, whereby the laser medium is excited and pulsed laser light is emitted.

The laser head 11 shown in FIG. 1 has a built-in beam shutter 111. This beam shutter 1
Reference numeral 11 controls ON / OFF of the pulse 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. The opening and closing operation time of the beam shutter 111 is about 100 to 300 msec. 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.

Further, as shown in FIG.
A dichroic mirror 120 and a condenser lens 121 having high reflectance characteristics with respect to the wavelength of the laser light are provided therein, and these configurations are the same as those of a conventional laser processing apparatus. In the present embodiment, the detection light source 122 that generates laser light as detection light, the collimator lens 1
23, half mirror 124, rotary wedge substrate device 3
A detection optical system 127 including an imaging lens 125 and a photodetector 126 is added. As the detection light source 122, a laser light source such as a laser diode (semiconductor laser) is used.
Is basically similar to the configuration of an optical system of an optical pickup unit for reading a disk signal of a CD player. Of course,
It goes without saying that the laser light used as the detection light is different from the laser light for performing the laser processing.

The rotary wedge substrate device 300 includes a single wedge substrate 301, a frame 302 supporting the wedge substrate 301, a pinion 303 attached to the outer periphery of the frame 302, a pinion 304 meshing with the pinion 303, and a pinion 304. It has a motor 305 that is driven to rotate. The frame 302, and thus the wedge substrate 301,
Is transmitted through the pinion 304 and the pinion 303, and rotates around the axis R of the wedge substrate 301 parallel to the original optical axis of the detection laser beam 200.
Any rotation angle can be set. Further, detection laser beam 200 incident on the wedge substrate 301 proceeds inclined by a predetermined angle phi ₁ to its original optical axis. The angle φ ₁ depends on the inclination angle θ ₁ of the slope of the wedge substrate 301.

As shown in FIG. 3, the trigger unit 24 includes a comparator 241 and a trigger signal generation circuit 2.
42, a gate circuit 245, a delay circuit 243, and a gate signal generator 244. In the trigger unit 24, the detection signal from the photodetector 126 is binarized by a comparator 241 at a certain threshold value V _TH to generate a rectangular wave signal TP, and the trigger signal generation circuit 2
At 42, trigger signals TP ₀ and TP ₀ ^* (described later) synchronized with the rise of the rectangular wave signal TP are output,
The trigger signals TP ₀ and TP ₀ ^* are input to the gate circuit 245. On the other hand, the gate signal generator 244 receives the trigger signal T from the trigger circuit 262 of the laser controller 26.
P ₂ enter the (described later), the trigger signal TP ₂ of the gate signals GP synchronized with the rising edge predetermined gate width W _G
To the gate circuit 245. The gate signal GP from the gate signal generator 244 is output from the gate circuit 245 as O.
If the FF (LOW) is the trigger signal TP _G p in synchronism with the rising edge of the trigger signal input from the trigger signal generating circuit 242 is output, the trigger from the trigger signal generating circuit 242 when the GP is ON (HIGH) No signal is output when a signal is input. Further, the trigger signal TP
_G is input to the delay circuit 243, where the command from the main controller 23 delay time T _D is output to the laser controller 26 as TP ₁ given. Note that the gate signal generator 244 and the gate circuit 245 constitute erroneous detection prevention means.

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. On the other hand, the trigger signal TP ₂ from the trigger circuit 262 is supplied to the gate signal generator ₂ of the trigger unit 24.
44 (see FIG. 3).

Returning to FIG. 2, the functions of the processing head 12 and the detection optical system 127 will be described. First, the pulse laser beam 100 oscillated from the laser head 11 is applied to the dichroic mirror 12
At 0, the direction is changed, and the light is condensed by the condenser lens 121 and irradiated onto the work 1. The detection light 200 emitted from the detection light source 122 is converted into parallel light by the collimator lens 123, passes through the half mirror 124, the wedge substrate 301, and the dichroic mirror 120, and forms a small spot on the work 1 by the condenser lens 121. Form an image.

Here, since the inclination angle of the slope of the wedge substrate 301 is constant at θ ₁ , the detection laser beam 200 emitted from the wedge substrate 301 is inclined at a constant angle φ _{1 with} respect to the original optical axis R. And proceed, the pulsed laser light 100
Reaches a position separated from the irradiation position by a certain distance r ₀ . The relationship between r ₀ and θ ₁ is as follows: When the focal length of the condenser lens 121 is F and the refractive index of the wedge substrate 301 with respect to the detection laser beam 200 is n, r ₀ = F · (n−1) · θ ₁ ... (1) Further, by rotating the wedge substrate 301 around its axis R, the detection laser beam 200
Can be formed at an arbitrary position on the circumference of a radius r ₀ centered on the condensing position (spot position) of the pulsed laser beam 100. The focusing position of the detection laser beam 200 based on the focusing position of the pulse laser beam 100 is represented by a vector [δ].
r], [δr] = (δr _x , δr _Y ) = (r ₀ cos ω, r ₀ sin ω) (2) Here, ω is the rotation angle of the wedge substrate 301 around the axis R.

The detection light 200 reflected on the surface of the work 1 is
After passing through the condenser lens 121, the dichroic mirror 120, the wedge substrate 301, and the half mirror 124, the imaging lens 12
5, the light is collected by the photodetector 126, and information on the surface of the work 1 is detected as an electric signal. In the present 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 condenser lens 1.
21 makes it possible to reduce the aperture very small, and when detecting information on the surface of the work 1 (such as the presence or absence of a lead), the rise (response) of a signal becomes faster and detection can be performed with high resolution.

The operation of the pulse laser processing apparatus having the above configuration will be described. FIG. 5 is a diagram showing a situation where the dam bar 2 on one side of the IC package is removed. The work 1 (IC package) is moved by the XY table 21 at a constant speed v in the positive direction of the X axis as shown in FIG.
Move the detection light 200 to a small spot.
Moves along the trajectory 5 on the work 1. This allows
The change in the detection signal detected by the photodetector 126 is high in the web section (lead section) 4 and low in the slit section 3. At this time, if the web portion 4 and the slit portion 3 of the work 1 are arranged at equal pitches, the detection signal when the XY table moves at a constant speed is detected as a waveform having a constant period. On the other hand, when the web portion 4 and the slit portion 3 of the work 1 are not arranged at the same pitch, the detection signal is detected as a waveform having a time change proportional to the change in the pitch.

However, as described above, the pulse laser beam 100
The focusing position of the detection laser beam 200 with reference to the focusing position of δr _X = r ₀ cosω in the _X -axis direction and δr _Y =
Despite being shifted by r ₀ sin ω, when moving in the positive direction of the X-axis, 270 ° <ω <0 ° (3), and the focus position of the detection light 200 moves with respect to the focus position of the pulse laser 100. Δr _x = r ₀ co in the direction (X-axis positive direction)
It precedes by sω. This way,
In the case where the focus position of the detection light 200 does not precede the focus position of the pulse laser 100 (δr _x = 0), the waveform has a time preceding T _AD = δr _x / v (FIG. 5 when δr _x ≠ 0).

When ω satisfies the above equation (3), the focus position of the detection light 200 is shifted in the negative Y-axis direction with respect to the focus position of the pulse laser 100 as shown in FIG. A certain δr _Y = r ₀ sin ω is a shift amount of the focus position (detection position) of the detection laser beam 200 from the dam bar center line in the lead longitudinal direction. However, δr is set so that the converging position of the detection light 200 crosses the parallel portion of the web portion 4 and scans.
Set _Y. In the present embodiment, the rotary wedge substrate device 300 is used. However, the condensing position of the detection light 200 is changed by other means, for example, by changing the angle of the half mirror 124.
It may be shifted with respect to the zero focusing position.

In this embodiment, the pulse laser beam 100 is applied to the center of the dam bar 2 to remove the dam bar as described later. However, when processing is performed by irradiating the workpiece with the laser beam as described above, From the processing position, a molten scattered substance (hereinafter referred to as “sputter”) 9 is generated. This spatter 9
Is attached to the web portion 4, the detection light 200 is scattered by the sputter 9 and affects the waveform of the detection signal detected by the photodetector 126. The portion corresponding to the sputter 9 is indicated by an arrow 9a in FIG. The output is low as shown.

The detection signal from the photodetector 126 is input to the trigger unit 24, and is binarized by the processing shown in the time chart of FIG. However, the horizontal axis in FIG. 6 indicates time, and in FIG. 6, the web portion 4 and the slit portion 3 when the work 1 is moved at a constant speed v are schematically shown as time changes. 4 and the slit portion 3 are based on the focusing position of the pulse laser 100, so that the waveform of the focusing position of the detection light 200 is
It is shifted by a leading amount with respect to the light condensing position of 0.

The detection signal input from the photodetector 126 to the trigger unit 24 is binarized by a comparator 241 based on a predetermined threshold voltage V _TH indicated by a broken line in the figure to become a square wave signal TP. Trigger signal generation circuit 242
Is input to At this time, the level of the detection signal of the detection light 200 scattered by the sputtering 9 (light intensity) is not problem if greater than the threshold value V _TH, V _TH as shown in FIG. 6
If it becomes smaller, the comparator 24 also detects a detection signal whose output level has dropped due to the sputtering 9.
1 will output a rectangular wave signal TP.
The trigger signal generation circuit 242 outputs trigger signals TP ₀ and TP ₀ ^* based on the rise of the rectangular wave signal TP. Here, the trigger signal TP ₀ is associated with the shape pattern of the work 1, and TP ₀ ^* is associated with the sputter 9 attached to the surface of the web portion 4. In the present embodiment, a gate circuit 245 and a gate signal generator 244 are provided in the trigger unit 24 in order to delete a signal (trigger signal TP ₀ ^* ) accompanying the sputter 9 attached to the surface of the web portion 4.

The trigger signals TP ₀ and TP ₀ ^* are supplied to the gate circuit 2
45, the gate circuit 245 outputs the gate signal GP from the gate signal generator 244 as described above.
In the case of F (LOW), the trigger signal TP _G synchronized with the rise of the trigger signal from the trigger signal generation circuit 242
When the GP is ON (HIGH), even if a trigger signal is input from the trigger signal generation circuit 242, a signal synchronized with the rise is not output. Trigger signal T
P _G is inputted to the delay circuit 243, the delay time T _D which is commanded from the main controller 23 to the trigger signal TP _G is input to the laser controller 26 as a trigger signal TP ₁ given. The detection signal from the photodetector 126 may be amplified by an amplifier before being input to the trigger unit 24.

[0038] Next, in the laser controller 26, the trigger signal TP ₁ is inputted 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. The pulse width of the trigger signal TP ₂ is indicated via the central processing unit 261 from the main controller 23 as described above. Moreover the trigger signal TP ₂ is input to the switch unit 132, the switch unit 132 in synchronization with the rising edge of the trigger signal TP ₂
Is turned on, and the condenser section 131 is connected to the excitation lamp 110.
Charge from is supplied further in synchronization with the falling edge of the trigger signal TP _2, the switch unit 132 is turned OFF,
The supply of the charge to the excitation lamp 110 is stopped. Pulsed laser light is oscillated in synchronization with the trigger signal TP ₂ as described above. Although the trigger signal TP ₂ and the pulsed laser light in the figure actually have a pulse waveform having a certain width, the pulse width is very short compared to other signals, and thus the trigger signal TP ₂ and the pulse laser light are shown in a linear shape in the figure. It is.

[0039] Further, the trigger signal TP ₂ is also inputted (fed back) to the gate signal generator 244, a gate signal GP synchronized to the rise of the trigger signal TP ₂ is outputted to the gate circuit 245 at a predetermined gate width W _G You.
That is, the gate signal GP will be output along with the generation of the trigger signal TP ₂ for lasing. The gate signal GP is generated under such conditions, and its gate width W
By setting _G to an appropriate length, the gate signal GP becomes OFF (LOW) when the trigger signal TP ₀ is output from the trigger signal generation circuit 242, and the gate signal GP adheres to the web section 4 from the trigger signal generation circuit 242. Spatter 9
Gate signal GP is ON (HIGH) when the trigger signal TP ₀ ^* is output accompanying. As a result, the gate circuit 245 in the trigger signal TP ₀ ^* is ignored, so that the trigger signal TP _G in synchronization with the rising of only the trigger signal TP ₀ is output. As a specific process in the gate circuit 245, the gate signal GP may be inverted, and the inverted signal may be ANDed with the trigger signal from the trigger signal generation circuit 242.

That is, when the dam bar 2 is cut, X
When the Y table is moved at a constant speed v along the processing locus, the pitch of the slit 3 and the web 4 and the table 2
The laser beam oscillates at a period determined by the moving speed v of 1 and the trigger signal TP ₀ ^* accompanying the sputter 9 is deleted, the laser beam is irradiated at the center of the dam bar 2, and the dam bar 2 is cut. You. Therefore, the dam bar 2 can be cut in a short period of time, about the oscillation cycle of the pulse laser beam 100, and reliable and high-speed processing can be performed.

If the trigger unit 24 has the gate circuit 2
45 and the gate signal generator 244 are not provided, not only the trigger signal TP ₁ output from the trigger signal generation circuit 242 but also the trigger signal T accompanying the sputtering 9
P ₀ ^* is likewise signal processing, not only the pulse laser light based on the trigger signal TP _0, also oscillates pulse laser light based on the trigger signal TP ₀ ^*. Thereby, the laser light 10
0 is the center of the target dam bar 2 and the dam bar 2
Irradiation to other positions is unnecessary, and predetermined laser processing cannot be realized.

In this embodiment, the trigger signal TP ₂ for laser light oscillation is fed back to the gate signal generator 244 to generate the gate signal GP, and the gate circuit 245
Since the trigger signal TP ₀ ^* associated with the sputter 9 from the trigger signal generation circuit 242 is deleted based on the gate signal GP, only the trigger signal TP ₀ associated with the pattern of the presence or absence of the web portion (lead portion) 4 is extracted. subsequent signal processing Te is performed, only the pulse laser light based on the trigger signal TP ₀ is oscillated. Therefore, the desired processing position is reliably irradiated with the laser beam in accordance with the presence or absence of the web portion 4 to perform the processing, and the laser beam is not unnecessarily irradiated to the wrong position other than the predetermined processing position. .

Here, the delay time T _D given by the delay circuit 243 will be described. When the moving speed of the workpiece 1 v, the width of the slit portion 3 and L _s, the detection light 200 detects the web portion 4 ends, the spot position of the pulse laser 100 before the web portion 4 slits The time T _{1 for} moving to the center of _{No. 3} is T ₁ = (δr _X −L _s / 2) / v (4) The time T ₂ from the rise of the rectangular wave signal TP ₀ to the irradiation of the pulse laser beam 100 to the dam bar ₂ is the delay time T _D given by the delay circuit 243.
T ₂ = T _D + δt (5) Here, δt is a delay in the trigger circuit 262,
This represents a total delay time of the delay in the switch unit 132 and the delay until laser oscillation.

The condition that the laser beam should be irradiated to the center of the dam bar 2 is as follows: T ₁ = T ₂ (6) From the equations (4) to (6), the delay time T _D becomes T _D = ( δr _X −L _s / 2) / v−δt (7) The delay time δt, the moving speed v of the work 1, the width L _s of the slit 3, and the vector [δr] are input to the main controller 23 in advance.

From the above equation (7), in order for the delay time T _{D to} be properly set, at least T _D > 0.
That is, it is necessary to satisfy δr _X > L _s / 2 + v · δt (8).

Next, the gate width W _{G of the} gate signal GP is _calculated.
The length will be described. The pulse laser beam 100 is irradiated at the center of the dam bar 2, and the pulse laser beam 10
Spatter does not occur before the irradiation of 0. Therefore, the minimum value of the gate width W _G from when the pulse laser beam 100 is irradiated on the center of the dam bar 2, the spot position of the detection light 200 is time to move to the end of the next web 4.
Therefore, when the L _u and the width of the web portion 4, the distance from the center position of the dam bar 2 to the next web 4 end, i.e., to move the distance _{δL 2 = L s / 2 +} L u -δr X ... (9) time is the minimum value of the gate width W _G.

Meanwhile, the maximum value of the gate width W _G from when the pulse laser beam 100 is irradiated on the center of the dam bar 2,
The spot position of the detection light 200 is further changed to the next web 4
Of the time to move to the _{beginning, δL 1 = (3/2) L} s + L u -δr X ... time to move the distance (10) is the maximum value of the gate width W _G.

[0048] Thus, the scope of the gate width W _{G is, δL 1 / v> W G} > δL 2 / v ... may be set so as to satisfy (11). The gate width W _G is also input in advance to the main controller 23.

In the above description, the case where the dam bar 2 on the side of the IC package shown in FIG. 5 is cut and removed has been mainly described, but subsequently, the dam bar 2 on each of the remaining three sides of the IC package is sequentially cut and removed. The case of removal will be described with reference to FIG. When the cutting of the dam bar on the side shown in FIG.
01 is rotated 90 ° counterclockwise about axis R.
Then, the processing position is moved by the XY table 21 in the positive direction of the Y-axis at a constant speed v, and the pulse laser The light bar 100 is used to cut and remove the dam bar 2. Next, after further rotating the wedge substrate 301 counterclockwise by 90 °, the processing position is moved by the XY table 21 in the negative direction of the X axis at a constant speed v, and based on the reflected light of the detection light 200 (trajectory 7). Based on the detection signal, the dam bar 2 is cut and removed by the pulse laser beam 100 as described above. Next, the wedge substrate 3
01 is further rotated counterclockwise by 90 °, and then X
The processing position is moved at a constant speed v in the negative direction of the Y axis by the Y table 21, and the pulse laser beam 100 is moved as described above based on the detection signal (along the trajectory 8) based on the reflected light of the detection light 200. The cutting and removal of the dam bar 2 are performed.
Thus, the cutting and removal of the dam bar 2 on all four sides of the IC package are completed.

The motor 305 for controlling the rotation of the wedge type prism 301 is controlled by the main controller 23.
Is automatically performed in synchronization with the movement of the XY table 21 in accordance with the trajectory. However, in FIG. 7, the vector [δ] of the focus position of the detection laser beam 200 is shown.
r] is indicated by an arrow corresponding to the cutting operation of the dam bar on each side of the IC package, and the condensing position of the detection laser beam 200 at the tip of the vector [δr] is indicated by 200A.

In the case of the present embodiment, the relative distance r ₀ between the irradiation position of the pulse laser light 100 and the irradiation position of the detection laser light 200 changes as long as the inclination angle θ ₁ of the slope of the wedge substrate 301 is constant. It not but which is constant, cutting dam bars of one IC package, when removed, since it is considered that the shape of the dam bar in the four sides are almost the same, even r ₀ is constant, each It is sufficient to rotate the wedge substrate 301 counterclockwise by 90 ° in accordance with the side. Further, when cutting and removing a dam bar of another IC package having the same shape, a similar method can be used using the same wedge substrate 301. Further, if the shape of the IC package are different, it may be changed wedge substrate having a tilt angle theta ₁ of different slopes accordingly.

According to the present embodiment as described above, the trigger signal TP ₂ for oscillating the pulse laser beam 100 is fed back to the gate signal generator 244 to generate the gate signal GP synchronized with the rising edge thereof, Circuit 2
At 45, the trigger signal generation circuit 2 based on the gate signal GP
Since the trigger signal TP ₀ ^* associated with the sputter 9 from the sample 42 is deleted, only the trigger signal TP ₀ associated with the pattern of the presence / absence of the web section 4 can be taken out, and the signal processing in the delay circuit 243 and the laser controller 26 thereafter performs , it is possible to oscillate the pulsed laser beam on the basis of only the trigger signal TP _0. Therefore, a predetermined processing position (the center part of the dam bar 2) is irradiated with the pulse laser beam in accordance with the shape pattern of the work 1 to perform the processing, and the pulse laser processing is unnecessarily performed at an erroneous position other than the predetermined processing position. Is not given.

Further, the dam bar 2 can be cut in a short period of time about the oscillation period of the pulse laser light determined by the pitch of the slit portion 3 and the web portion 4 and the moving speed v of the XY table 21, thereby ensuring reliable and high-speed processing. Becomes possible.

Further, since the pulse laser beam is applied to a position separated by a certain distance from the end of the web portion 4, the shape of the work 1 can be obtained not only when the pins are at equal intervals but also when the pins are not at equal intervals. A predetermined position to be cut can be processed reliably and at high speed in accordance with the condition.

[0055]

According to the present invention, the detection signal based on the presence or absence of the workpiece is excluded from the detection signal based on the light from the vicinity of the processing position, except for the change caused by the molten scattered matter (spatter) attached to the work surface. Since the oscillation of the pulse laser light is controlled based only on the laser beam, the laser beam can be reliably irradiated to the desired processing position in accordance with the information on the surface of the workpiece, and the processing can be performed. There is no unnecessary irradiation of the wrong position with the laser beam. Further, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals, it is possible to perform high-speed processing at a predetermined processing position.

[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 diagram illustrating a correspondence between a dam bar and a detection signal from a photodetector.

FIG. 6 is a time chart from output of a detection signal from a photodetector to oscillation of laser light.

FIG. 7 is a diagram showing a situation in which dam bars on each of four sides of an IC package are sequentially cut and removed.

FIG. 8 is a schematic diagram of a configuration of a conventional laser processing apparatus.

9A is a diagram showing an IC package having a dam bar, and FIG. 9B is an enlarged view of a portion B in FIG. 9A.

[Explanation of symbols]

Reference Signs List 1 work 2 dam bar 3 slit section 4 web section 10 laser oscillator 11 laser head 12 processing head 13 laser power supply 21 XY table 22 Z table 23 main controller 24 trigger unit 25 control unit 26 laser controller 100 pulse laser beam 120 dichroic mirror 121 condensing Lens 122 Detection light source 123 Collimator lens 124 Half mirror 125 Imaging lens 126 Photodetector 127 Detection optical system 130 Stabilized power supply unit 131 Capacitor unit 132 Switch unit 133 AC power supply 200 Detection light 200A Focusing position 241 of detection laser light 200 Comparator 242 Trigger signal generation circuit 243 Delay circuit 244 Gate signal generator 245 Gate circuit 261 Central processing unit 262 Trigger circuit 00 rotary wedge board device 301 wedge substrate 305 motor TP _1, TP ₂ trigger signal GP gate signal

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinya Okumura 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Inside the Tsuchiura Plant (72) Inventor Yasushi Minomoto 650, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture Inside Hitachi Construction Machinery Engineering Co., Ltd. (56) References JP-A-1-316463 (JP, A) JP-A-2-67717 (JP) JP-A-4-37493 (JP, A) JP-A-58-75050 (JP, A) JP-A-4-1508 (JP, A) JP-A-2-133656 (JP, U) Field surveyed (Int. Cl. ⁷ , DB name) B23K 26/00 B23K 26/08 H01L 23/50 H01S 3/00 H01S 3/10

Claims (3)

(57) [Claims] 1. A laser oscillator that oscillates a pulsed laser beam based on a trigger signal, a processing optical system that guides the laser beam to a processing position of the workpiece, and a process that moves the workpiece to process the workpiece. A laser processing apparatus comprising: a conveying unit that determines a position; a detection light source that generates detection light for detecting the presence or absence of a workpiece near the processing position; and reflected light of the detection light from near the processing position. Detecting means for detecting the reflected light and generating a detection signal corresponding to the reflected light; and generating a trigger signal for oscillating the pulsed laser light.
Generates a gate signal with a gate width of a predetermined period from the raw
A gate signal generator, and a detection signal generated from the detection means are input,
Gate width of the gate signal generated by the gate signal generator
A game that outputs only detection signals generated during periods other than
And a trigger signal based on a detection signal output from the gate circuit and the detection signal output from the gate circuit so that the predetermined processing position of the workpiece is irradiated with the laser light, thereby controlling the oscillation of the laser light. Control means, the processing position of the detection signal during laser processing.
Signal generated due to melted splatters attached near the equipment
Number, and the presence or absence of the workpiece near the machining position
Extracts only the detection signal based on
A laser processing apparatus characterized in that laser processing is performed by controlling the oscillation of laser light based on a laser beam . 2. A processing position is determined by moving a workpiece.
In a laser processing method of processing the workpiece by irradiating a pulsed laser beam from a laser oscillator to the processing position based on a trigger signal, a detection for detecting the presence or absence of the workpiece near the processing position Light is irradiated to the vicinity of the processing position , and the reflected light
And among the detection signals corresponding to the detected reflected light, the trigger
A gate signal having a gate width for a predetermined period from generation of a signal
Of the detection signals generated in a period other than the gate width
At the predetermined processing position of the workpiece based on the
The trigger signal is output so that the light is irradiated,
Controlling the oscillation of the laser light, and among the detection signals corresponding to the reflected light,
Generated due to melted splatters attached near the processing position
The detection signal corresponding to the reflected light
Only based on the detection signal based on the presence or absence of the workpiece nearby
And performing laser processing by controlling the oscillation of laser light . The 3. A dam bar in mounting the semiconductor chip on the lead frame IC package sealed together with a resin mold, based on the trigger signal, the dam bar machining method of cutting by laser beam irradiation of the pulsed, the test Idemitsu Irradiates near the dam bar and detects the reflected light
Out of the detection signal corresponding to the detected reflected light.
A gate having a gate width for a predetermined period from the generation of a trigger signal
Detection signal generated during a period other than within this gate width
No. only at the specified processing position of the dam bar based on the
The trigger signal is output so that the laser light is emitted,
Controlling the oscillation of the laser light, and among the detection signals corresponding to the reflected light,
Generated due to melted splatters attached near the processing position
The detection signal corresponding to the reflected light
Only based on the detection signal based on the presence or absence of the workpiece nearby
And performing laser processing by controlling the oscillation of laser light .