JP2000288762A - Method and device for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct high speed and precise machining with correcting a machining position deviation due to positioning error and without lowering productivity in a simple constitution. SOLUTION: A lead frame 1a is supplied form a transfer device 6 to a jig 7 and is fixed. When operating a galvono-mirror 42, detection light from a detection light source 8 coaxially arranged to a machining laser beam is moved on the lead frame 1a. The detection light radiated on a lead pin is reflected with the lead pin and not reaches a detection means 9, however, the detection light passes between the lead pins and reaches a photo sensor 92 through an image forming lens 91. A detection signal of a sensor 92 is binarized with a control means 10, based on the above, a controller 41 controls the mirror 42. By this operation, the detection light from the mirror 42 is precisely stopped at a fixed machining position A. The controller 41, after the detection light is stopped, outputs an irradiation start signal to a laser beam oscillator 2, the machining position is precisely irradiated with the laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a high-speed positioning using a galvanometer mirror for laser beam transmission,
The present invention relates to a laser processing method and apparatus for performing laser processing.

[0002]

2. Description of the Related Art A conventional processing apparatus using a galvanometer mirror for transmitting a laser beam will be described with reference to FIG. As shown in FIG. 6, a laser processing apparatus having a conventional configuration includes a laser oscillator 3 having a laser head 31 and a laser power source 32, a galvano controller 41,
A galvano scanner 4 configured by an axis galvanometer mirror 42 and a Y-axis galvanometer mirror 43 and transmitting a laser beam output from the laser oscillator 3 and scanning in the XY directions;
And a condenser lens 5 for condensing the laser beam.

Here, when the irradiation position changes only in one axis direction, the galvano scanner 4 includes a galvano controller 41 and a one-axis galvanometer mirror 42. When used on a production line, etc., supply of work 1
A transport device 6 for collecting and a jig 7 for fixing the work 1 are added.

[0004]

A description will be given of an example of laser processing in which positioning is repeated at high speed, such as superposition welding of lead pins of a lead frame, using the above-described laser processing apparatus. FIG. 7 is an explanatory diagram of lap welding of the lead pins, as viewed from the top surface of the lead frame 1a. FIG. 8 is an explanatory view of overlap welding of lead pins, similarly to FIG. 7, and is a perspective view showing a state in which two lead pins 2a and 2b are overlapped.

In FIG. 7, the procedure for laser welding one side of the lead pin 2a is as follows. The laser is irradiated at the first welding position A, and the laser irradiation position is moved to the welding position B of the next lead pin 2a by the galvano scanner 4. Then, laser irradiation is performed. As described above, the laser is irradiated at the position on the lead pin 2a between the start pin A and the last pin E by repeatedly moving the distance corresponding to the lead pitch.

When the lead frame 1a is supplied and fixed to the jig 7 by the transfer device 6 using the above-described processing procedure and the lead pins 2a and 2b are laser-welded, the following (1) to (3) The following positioning error occurs.

(1) When the lead frame 1a is supplied from the transfer device 6 to the jig 7, usually the lead frame 1a
Positioning is performed such that a pin on the jig 7 is fitted and inserted into the upper round hole. At this time, the round hole and the pin
Since a gap of about μm is set, a positioning error of 10 μm or more occurs.

(2) If a thin material such as the lead frame 1a is used and there is a heat history due to a heating process such as a molding process, thermal contraction occurs, and the pitch between the lead pins 2a is not always a design value. It does not match.

(3) The galvano scanner 4 is an open control for positioning the galvanometer mirrors 42 and 43 by instructing a voltage corresponding to the position. In addition, the position corresponding to the zero point and the voltage is affected by a change in the ambient temperature. Also changes, the gain of the positioning may be large.

When the positioning errors as described above are accumulated, the welding position may be shifted from the position on the lead pin 2a. If the welding position is misaligned,
A certain bonding area cannot be obtained between a and 2b, and the resin in the dam is irradiated with a laser and the resin scatters, so that sufficient solder adhesion strength cannot be obtained in the next solder plating step. I do.

As a method for correcting an error when the work 1 is fixed, an error due to distortion of the whole work 1, and the like, there is, for example, a "laser beam irradiation apparatus" described in Japanese Patent Application Laid-Open No. 2-44201. In Japanese Patent Application Laid-Open No. 2-44201, a CCD camera captures a position shift of an irradiation target on a moving stage reflected by a galvanometer mirror and a dichroic mirror, and performs a correction operation for correcting the position shift based on the position shift. It is described.

Although it does not relate to the processing of a lead frame, the "apparatus and method for manufacturing a multilayer printed wiring board" described in Japanese Patent Application Laid-Open No. 10-150279 discloses a method in which target marks are formed at four corners of a substrate. The position of this target mark is measured with a CCD camera, the position of the substrate is actually measured, and from the processing data and the actually measured value of the position of the substrate,
It describes that the displacement of the substrate position is corrected and drive data for the galvano head and the XY table is created.

What is described in the above two publications is CC
This is a method of correcting the positional deviation by capturing the reference point of the work 1 with the D camera and performing image processing. The errors that can be corrected by these methods are as follows.

(1) Since the position of the reference point of the work 1 fixed to the jig 7 is corrected by image processing, an error when the work 1 is fixed to the jig 7 can be corrected.

(2) If the reference points of the work 1 are, for example, the starting point and the ending point of the machining, the positional deviation between the starting point and the ending point can be corrected.

(3) When the image of the work 1 is captured by the CCD camera, the mirrors 42 and 43 of the galvano scanner 4 are used.
The error caused by the drift of the zero point and the gain of the galvano scanner 4 can be corrected through the above.

However, as shown in (2), the displacement between the starting point and the ending point of the processing can be corrected, but the processing points other than the starting point and the ending point cannot be corrected. Further, if it is attempted to correct all the processing positions other than the start point and the end point by image processing, the processing time becomes longer as the number of processing points increases, and the productivity is reduced. That is, it is necessary to accurately specify each processing point, enlarge the processing point, and correct the position shift by image processing. In this case, as described above, as the number of processing points increases, the processing time increases, and the productivity decreases.

Further, as shown in (3), even if the zero point and the gain of the galvano scanner 4 can be corrected, the machining position between the reference points is controlled to be open. Even in the absence state, an error of about ± 20 μm occurs. Further, since image processing time by the CCD is required, productivity is reduced accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser processing method and a laser processing apparatus which are capable of performing high-accuracy and high-speed processing without compromising productivity while compensating for a shift in a processing position due to a positioning error while having a simple structure. It is to realize.

[0020]

In order to achieve the above object, the present invention is configured as follows. (1) Processing laser light oscillated from a laser oscillator is
In a laser processing method of performing laser processing on the workpiece by guiding the workpiece to the workpiece using a galvanometer mirror and controlling the irradiation position of the laser beam on the workpiece at high speed, the processing laser The workpiece is irradiated with detection light having an optical axis substantially coaxial with the optical axis of the light, and reflected light of the detection light from the surface of the workpiece or light passing through the workpiece is detected. The change position of the surface of the object is detected, and based on the detected change position, the operation of the galvanomirror is controlled to perform the irradiation positioning of the processing laser light.

(2) A laser oscillator for oscillating a laser beam for processing, and a laser oscillator for guiding the laser beam to a workpiece and controlling the irradiation position of the laser beam on the workpiece at high speed. In a laser processing apparatus having a processing optical system having a galvanometer mirror, the laser processing apparatus has an optical axis substantially coaxial with the optical axis of the processing laser, and is irradiated on the workpiece,
A detection light source that generates detection light for detecting a change in the surface of the workpiece, and a reflected light or a passing light of the detection light generated from the detection light source, which corresponds to the detected light. A detection unit that generates a detection signal; and a control unit that controls irradiation of the processing laser light based on the detection signal and controls a stop operation of the galvanomirror.

In the present invention configured as described above,
The workpiece is irradiated with detection light having an optical axis that is coaxial with the optical axis of the processing laser light, and the reflected light of the detection light from the surface of the workpiece or the light that has passed through the workpiece is detected. A change position of a workpiece, for example, in the case of a lead frame, an edge position of a lead pin is detected.

A signal indicating this change position is given a predetermined delay time and input to a control means for controlling the operation of the galvanomirror. The control unit controls the irradiation of the processing laser based on the input signal and controls the operation of the galvanomirror to perform the processing laser irradiation. As a result, closed-loop control based on the processing position of the workpiece can be performed, and highly accurate positioning processing can be performed. Further, unlike the image processing, there is no need to perform only a process for correcting the positional deviation, and the productivity is not reduced because the position is corrected in a series of processing operations.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing method and apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings, taking an example in which the method and apparatus are applied to lead frame welding.
FIG. 1 is an overall schematic configuration diagram of a laser processing apparatus according to one embodiment of the present invention. As shown in FIG. 1, a laser processing apparatus according to one embodiment of the present invention includes a laser head 31.
And a laser oscillator 3 having a laser power supply 32, a galvano controller 41, an X-axis galvanometer mirror 42, and a Y-axis galvanometer mirror 43, and transmitting a laser beam output from the laser oscillator 3 and scanning in the XY directions. 4 and a condenser lens 5 for condensing the laser beam
A detection light source 8 having an optical axis coaxial with the optical axis of the processing laser and generating detection light irradiated to the workpiece, and a detection light amount received by receiving the detection light from the detection light source 8 And a control means 10 for controlling the stopping operation of the galvanomirrors 42 and 43 based on the signal from the detection means 9.

For example, in the case of welding a lead frame, the detecting means 9 is provided on the laser passage side. The detection means 9 includes an imaging lens 91 and a photo sensor 92. The imaging lens 91 is a lens for causing the photo sensor 92 to receive the detection light passing through the lead frame 1a. The photo sensor 92 detects the detection light that has passed through the lead frame 1a.

FIG. 2 is an internal configuration diagram of the control means 10 shown in FIG. 2, the control unit 10 includes a comparator 101 and a delay circuit 102.

The operation of the laser processing apparatus having the above configuration will be described. First, the lead frame 1a is transferred from the transfer device 6.
Is supplied to the work fixing jig 7 and is fixed on the jig 7. Then, as shown in FIG. 3, the fixed lead frame 1a is moved in the direction from the start point O to the processing start point A in accordance with the trajectory set in advance by the galvano controller 41. Lead pin 2a
Is moved in the direction of the machining position, and finally sequentially moved in the direction of the machining end point E.

Here, a processing cycle of one lead pin will be described with reference to a time chart of FIG. In FIG. 4, when the galvanometer mirror 42 is operated in the direction from the start point O to the processing start point A, the moving speed of the irradiation position by the galvanometer mirror 42 is accelerated at a certain acceleration as shown in FIG. After reaching a predetermined speed, it moves at a constant speed. The detection light from the detection light source 8 installed coaxially with the processing laser starts to move from the start point O on the lead frame 1a to the processing start point A together with the operation of the galvanomirror 42.

At this time, the detection light irradiated onto the lead pin 2a is reflected by the lead pin 2a and does not reach the detecting means 9, but the detection light passes through the gap between the lead pins 2a and 2a and passes through the imaging lens 91. Through the photo sensor 9
Reach 2 Thus, the detection light of the photo sensor 92 changes as shown in FIG. 4B depending on the presence or absence of the lead pin 2a. That is, the detection light of the photo sensor 92 becomes larger than the threshold level at the position where the lead pin 2a exists, and becomes smaller than the threshold level at the gap between the lead pins 2a and 2a.

The detection signal of the photo sensor 92 is input to the comparator 101 of the control means 10 and is binarized at the preset threshold level to be a rectangular signal as shown in FIG. Then, the binarized rectangular signal is delayed by a predetermined time td by the delay circuit 102, becomes a rectangular signal as shown in FIG. 4D, and is input to the galvano controller 41. The galvano controller 41 stops the galvanomirror 42 at the time when the input signal from the delay circuit 102 falls.

Here, when the distance from the edge of the lead pin 2a to the processing position A is d, and the edge coincides with the falling edge of the rectangular signal of the comparator 101 and the acceleration / deceleration of the galvanomirror 42 is linear, the following relationship is obtained. Equation (1) holds. d = v (t1 + td) + v · t2 / 2 (1) where, in the above equation (1), v is a galvanomirror 4
The moving speed of t2, t1 is a delay time until deceleration is actually started by a stop command of the galvano controller 41, td is a delay time by the delay circuit 102, and t2 is a deceleration time.

From the above equation (1), the delay time td for stopping at the machining position A is calculated by the following equation (2). td = (dv · t2 / 2) / v−t1 (2) When the acceleration / deceleration is not a straight line, and the edge position of the lead pin 2a does not coincide with the falling edge of the rectangular signal from the comparator 101 In this case, the delay time td may be adjusted in consideration of the distance. By the above operation, the detection light from the galvanomirror 42 stops at the predetermined processing position A with high accuracy.

After stopping the detection light, the galvano controller 41 outputs a laser light irradiation start signal to the laser oscillator 2. Laser oscillator 2 that receives irradiation start signal
Outputs the irradiation completion signal to the galvano controller 41 after the laser irradiation for a predetermined time. Next, upon receiving the irradiation completion signal, the galvano controller 41 starts moving the detection light to the next processing position B. Then, similarly to the processing position A, the processing position B is detected and laser processing is performed.

By repeating the above operation, the processing of one side of the lead frame 1a is completed. The lead pin 2a of the next side is moved to the starting point O, and the same operation is performed to perform laser processing of the next one side. .

As described above, according to the embodiment of the present invention, the detection light coaxial with the optical axis of the processing laser light is irradiated while moving one side of the lead frame 1a, and the lead pin 2a is irradiated.
Since the processing position of the lead pin 2a is detected by detecting the detection light passing through the gap between the lead pin 2a and the processing position, the processing position is irradiated with the processing laser light. It is possible to realize a laser processing method and a laser processing apparatus capable of correcting a shift of a processing position due to an error and performing high-precision and high-speed processing without lowering productivity.

In the embodiment of the present invention described above,
The case where there is a space through which the detection light passes like a lead frame has been described as an example. However, for example, when laser processing is performed on a pattern wired on a printed board, there is no space through which the detection light passes. Also, as shown in the example of FIG. 1, there is a space where the detection light passes through the work 1,
There is a case where there is no appropriate space at a position where the detection light that has passed through the work 1 is detected, and the detection means cannot be arranged.

In such a case, as in another embodiment of the present invention shown in FIG. 5, the reflected light of the detection light from the work surface is used. That is, in FIG. 5, the beam splitter 93 is disposed between the laser head 31 and the galvanometer mirror 42 and on the path of the laser light. Then, the reflected light of the beam splitter 93 is arranged so as to irradiate the photosensor 92 via the imaging lens 91, and an output signal from the photosensor 92 is input to the control unit 10.

In the configuration shown in FIG. 5, the detection light from the detection light source 8 passes through the beam splitter 93,
The work 1 is irradiated through the galvanometer mirrors 42 and 43 and the condenser lens 5.

Then, the detection light is reflected on the surface of the work 1, collimated by the condenser lens 5, almost collimated, reflected by the galvanometer mirrors 42 and 43, further reflected by the beam splitter 93, and collected by the imaging lens 91. The light is incident on the photo sensor 92.

The amount of detection light incident on the photo sensor 92 is large when the material of the work 1 has a high reflectance and the surface roughness is small, and conversely when the reflectance is low and the surface roughness is large and the inclination is large. Becomes smaller.

As described above, the received light amount of the detection light changes due to the pattern in which the reflection characteristic of the work 1 is different. Positioning can be performed with high accuracy.

However, the example of FIG. 5 can be applied only when the difference in reflectance between the patterns provided on the surface of the work 1 is large.

[0043]

According to the present invention, the positional deviation due to the dimensional error of the work during laser processing, the positioning error due to the moving means, the positioning error during the supply of the lead frame by the transfer device, and the like can be reduced by the edge of the work itself. Detect
Since the processing is performed by determining the processing position based on the edge, high-precision positioning processing becomes possible.
In addition, since the edge of the work is detected and processed in real time in a series of processing operations, no processing time is required for position correction, and productivity is not reduced.

That is, it is possible to realize a laser processing method and a laser processing apparatus capable of correcting a shift of a processing position due to a positioning error and performing high-precision and high-speed processing without lowering productivity, with a simple configuration. Can be.

[Brief description of the drawings]

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

FIG. 2 is an internal configuration diagram of a control unit in the example of FIG.

FIG. 3 is an explanatory diagram of a laser processing locus in the present invention.

FIG. 4 is a time chart of one cycle of processing in the present invention.

FIG. 5 is an overall configuration diagram of a laser processing apparatus according to another embodiment of the present invention.

FIG. 6 is an overall schematic configuration diagram of a laser processing apparatus according to the related art.

FIG. 7 is an explanatory view of lap welding of lead pins;
It is a top view of a lead frame.

FIG. 8 is an explanatory view of lap welding of lead pins;
It is a perspective view in the state where two lead pins were overlapped.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Work 1a Lead frame 2a Lead frame 3 Laser oscillator 4 Galvano scanner 5 Condensing lens 6 Transfer device 7 Work fixing jig 8 Detecting light source 9 Detecting means 10 Control means 31 Laser head 32 Laser power supply 41 Galvano controller 42 X axis galvanomirror 43 Y-axis galvanometer mirror 91 imaging lens 92 photosensor 93 beam splitter 101 comparator 102 delay circuit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Makoto Ishijima 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 4E068 CA09 CB08 CB09 CC06 CE03 DA09

Claims (2)

[Claims] 1. A laser beam for processing oscillated from a laser oscillator is guided to a workpiece using a galvanometer mirror.
A laser processing method of laser-processing the workpiece by controlling the irradiation position of the laser light on the workpiece at high speed; and detecting a laser beam having an optical axis substantially coaxial with the optical axis of the processing laser light. By irradiating the workpiece with light, the reflected light of the detection light from the workpiece surface or the light passing through the workpiece is detected, and the change position of the surface of the workpiece is detected. By controlling the operation of the galvanomirror based on the change position,
A laser processing method, wherein the irradiation position of the processing laser light is determined. 2. A laser oscillator for oscillating laser light for processing, and a galvanomirror for guiding the laser light to a workpiece and controlling an irradiation position of the laser light on the workpiece at high speed. A processing optical system having a processing optical system having an optical axis substantially coaxial with the optical axis of the processing laser, irradiating the processing object, and detecting a change in the surface of the processing object. A detection light source that generates light; a detection unit that detects reflected light or passing light of the detection light generated from the detection light source from the workpiece and generates a detection signal corresponding to the detected light; Control means for controlling the irradiation of the processing laser on the basis of a signal and for controlling the stopping operation of the galvanomirror.