TW202100272A - Laser beam abnormality detection method and laser processing apparatus - Google Patents

Abstract

A laser beam used in a laser processing apparatus is susceptible to abnormalities due to burns inside a laser oscillator and the like. Before these abnormalities are exposed by low output, they are often revealed in the beam diameter and beam profile. If the output is used as an indicator, the abnormality detection will be delayed. The laser beam abnormality detection method of the present invention is a method of detecting laser beam abnormality in a laser processing apparatus provided with a laser oscillator that emits a laser beam, and the laser beam abnormality detection method includes the following steps: an irradiation step which irradiates a laser beam, in a defocused state from the surface of the pre-adjustment substrate, to a pre-adjustment substrate provided outside a processing area where a material is processed by the laser beam; an imaging step which acquires imaging information by imaging irradiation marks on the pre-adjustment substrate formed in the irradiation step by imaging means; and a judging step which judges the abnormality of the laser beam based on the above-mentioned imaging information. The aforementioned steps are performed before judging the abnormality of the output of the laser beam.

Description

Abnormal detection method of laser beam and laser processing device

The present invention relates to a method for detecting abnormality of a laser beam.

Laser oscillators are generally used in laser processing devices for cutting, welding, and drilling. The laser oscillator is configured to emit the oscillated laser to the outside through an optical system such as a partial reflection mirror and a total reflection mirror. However, the energy density of the laser is very high, and the oscillator and optical system malfunction. Abnormalities occur frequently. For example, the use of carbon dioxide lasers may cause the optical system to burn out. In addition, there may also be cases in which abnormalities occur in the mirror and head outside the laser oscillator due to the light energy of the laser. The above-mentioned abnormalities will not only occur over time, but also occur suddenly. Therefore, it is necessary to detect abnormalities in laser oscillators and the like early.

The following Patent Document 1 discloses a conventional abnormality detection method of a laser oscillator. Specifically, in the abnormality detection method disclosed in Patent Document 1, a beam diameter diagnostic area (area) of a laser beam is provided outside the work processing area, and the laser beam is irradiated in the beam diameter diagnostic area bundle. When the laser oscillator is abnormal, the beam diameter becomes a value different from the usual value. Therefore, in the aforementioned abnormality detection method, the beam diameter of the laser beam irradiated in the beam diameter diagnosis area is measured, and when the measured beam diameter is different from the normal value, an abnormality is detected. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2008-114228

[The problem to be solved by the invention]

The above-mentioned Patent Document 1 discloses a method of detecting abnormalities of the partial and total reflection mirrors of the laser oscillator by measuring the beam diameter as a diagnostic process, but when the laser beam output is diagnosed If there is no abnormality in the system, the beam diameter diagnostic procedure will not be performed. That is, when the output of the laser beam is not lower than a certain reference value, the beam diameter diagnosis will not be performed. This is based on the premise that the laser beam output will be abnormal when the laser beam is abnormal. However, even though the output of the laser beam is normal, there may still be abnormalities in the reflector and the irradiation head outside the laser oscillator other than the partial reflector and total reflector of the laser oscillator. The method of Document 1 cannot detect abnormalities in this situation.

The present invention is developed to solve the above-mentioned problems, and aims to provide an early detection method for abnormalities that are not exposed in the output of the laser beam. [Means to solve the problem]

The abnormality detection method of the laser beam of the present disclosure is a method for detecting abnormality of the laser beam in a laser processing device equipped with a laser oscillator that emits the laser beam; the abnormality detection method of the laser beam has the following steps : The irradiation step is to set the pre-adjustment substrate outside the processing area of the material to be processed by the laser beam, in a state of defocusing from the surface of the pre-adjustment substrate Irradiate the laser beam; the imaging step (step) is to obtain imaging information by imaging the irradiation marks on the substrate for pre-adjustment formed by the preceding irradiation step by imaging means; the measurement step is based on the imaging Information, measuring the shape parameter (parameter) related to the shape of the aforementioned irradiation mark; and the determining step, when the measurement result of the aforementioned measuring step exceeds the range indicating that the laser beam is normal, it is determined that the laser beam is abnormal. [Effects of the invention]

According to the laser beam abnormality detection method disclosed in the present disclosure, it is possible to detect the abnormality of the laser beam early even if the output of the laser beam is not exposed. In addition, by stopping the production by laser processing when the abnormality of the laser beam is detected, the continuous production of defective products can be stopped.

Hereinafter, the implementation mode will be explained using the appended drawings. In each figure, the same reference numerals are given to the same or equivalent parts. The repeated description is simplified or omitted as appropriate. In addition, the present invention is not limited by the following embodiments.

Implementation type 1. Fig. 1 is a diagram of a laser processing apparatus for explaining the laser beam abnormality detection method of the first embodiment. The configuration of the laser processing apparatus 100 is only an example, and the configuration can be changed as necessary.

The laser processing device 100 is equipped with a laser oscillator 1, a mirror 3, a scanner mirror 4a, a lens 4b, a stage 6, a driving mechanism 7a and 7b, a camera 8 and image processing Device 9. The laser oscillator 1 is a pulsed laser oscillator, which emits a laser beam 2. The laser beam 2 is reflected by the mirror 3 and then scanned along the X and Y directions by the scanning mirror 4a. The laser beam 2 is focused on the workpiece 5a by the lens 4b, whereby the workpiece 5a is subjected to laser processing. The table 6 on which the workpiece 5a is stored is movable in the two-dimensional direction of X and Y by the drive mechanism 7b. Thereby, the laser beam 2 can be irradiated to the arbitrary place of the to-be-processed object 5a. The irradiation head 4 composed of the scanning mirror 4a and the lens 4b can be moved in the vertical direction by the driving mechanism 7a. Thereby, the focus of the laser beam 2 can be focused on the surface of the workpiece 5a (just focus), or the focus can be moved away from the surface (defocus). The camera 8 performs surface observation of the workpiece 5a. The image processing device 9 can acquire and analyze various data (data) described later by processing an image captured by the camera 8.

The carrier 6 will be described in detail. The stage 6 has a processing area 6a for storing the workpiece 5a, and an out-of-processing area 6b for storing the workpiece 5b for pre-adjustment. The workpiece 5b is formed of, for example, a resin substrate such as solder resist and acrylic. Next, the pre-adjustment operation will be described. When mass production processing of the workpiece 5a is started with the laser processing device 100, a pre-adjustment operation is performed before the processing starts. Pre-adjustment operations are also carried out regularly in mass production processing, so pre-adjustment operations are performed several times a day. In the pre-adjustment operation, the laser beam 2 is irradiated to the workpiece 5b stored in the unprocessed area 6b to perform various corrections. Regarding the correction, the relative position of the optical axis of the laser beam 2 passing through the lens 4b and the optical axis of the camera 8 is corrected, and the relative relationship between the swing angle of the scanning mirror 4a and the scanning distance of the laser beam 2 is corrected.

The abnormality detection of the laser beam 2 of this embodiment 1 is performed by actually irradiating the laser beam 2 to the workpiece 5b. Regarding the irradiation of the laser beam 2 on the workpiece 5b, the focal position of the laser beam 2 is focused on a position defocused from the surface of the workpiece 5b. When laser irradiation is performed on the workpiece 5b, irradiation marks are formed. The irradiation mark is captured by the camera 8 to obtain an image of the irradiation mark. The image processing device 9 processes the acquired image of the irradiation mark, and measures parameters related to the shape of the irradiation mark. The laser processing device 100 determines whether the measured shape parameter falls within a preset range. If the shape parameter is outside the above range, it is determined that the laser beam 2 is abnormal, and the abnormality is output. Thereby, even if the abnormality of the output drop of the laser beam 2 is not revealed, the abnormality of the laser beam 2 can be detected. The feature of the laser beam 2 abnormality detection method of this embodiment 1 is that before performing abnormal detection of the low output of the laser beam 2, the abnormality judgment of the laser beam 2 based on the imaging information is performed to detect the laser beam 2 exceptions.

When the laser beam 2 is irradiated to the workpiece 5b, as long as the laser oscillator 1, the mirror 3, and the irradiating head 4 are normal, the irradiation mark, that is, the processing hole system becomes a substantially circular shape. In other words, when the laser beam 2 is normal, the irradiation mark on the workpiece 5b by the laser beam 2 becomes a substantially circular shape. The reason why the focus of the laser beam 2 is focused not on the surface of the workpiece 5b but at a position defocused from the surface is because when an abnormality is recognized in the laser beam 2, the effect of the abnormality is likely to be significant. It is revealed in the exposure marks. For example, when the transmission mirror in the laser oscillator 1 is damaged, the influence caused by the damage to the transmission mirror is revealed in the shape of the irradiation mark. In addition, when the mirror 3 and the irradiation head 4 outside the laser oscillator 1 are damaged, the influence caused by the damage of the mirror 3 and the irradiation head 4 is revealed in the shape of the irradiation mark. At this time, even if the output of the laser beam 2 is maintained and normal, the irradiation marks of the irradiated laser beam 2 at a position defocused from the surface will still be horseshoe-shaped and doughnut-shaped as shown in Figures 2 to 3 . Regarding the defocusing direction, when the direction toward the lens 4b is a positive direction with the surface of the workpiece 5b as the reference plane, the defocusing position can be set in either positive or negative direction. In order to obtain a clearer irradiation mark and to avoid physical interference between various devices in the laser processing apparatus 100, it is preferable to set the focal position 10 of the laser beam 2 formed by the lens 4b on the positive side. Defocus position. Regarding the defocus amount df calculated from the surface of the workpiece 5b, when 1 mm to 5 mm is used, it is easy to obtain the horseshoe-shaped and doughnut-shaped irradiation marks 20 when the laser beam 2 is abnormal, which is preferable. As a result, the abnormality of the laser beam 2 can be easily detected.

To obtain the shape parameter from the irradiation mark, it is obtained by processing the image captured by the camera 8 with the image processing device 9. The image processing device 9 converts the image captured by the camera 8 into black and white binarized data. Then, the outline of the irradiation mark is extracted from the binarized data, and a data group representing the irradiation mark is obtained. The image processing device 9 acquires parameters (shape parameters) related to the shape of the circular irradiation mark from the extracted data group of the contour of the irradiation mark. In terms of shape parameters, (1) center of gravity coordinates, (2) diameter, (3) true circle ratio, (4) degree of agreement with a true circle with target diameter (hereinafter referred to as degree of agreement), etc. data. For (3) the true roundness, the system can use the general ellipse equation for the obtained data group, and fit the least square method to obtain the major and minor diameters of the ellipse. The ratio is obtained. In addition, for (4) the degree of coincidence, it is possible to set the diameter (target diameter) of the intended irradiation mark to be obtained by the irradiation of the laser beam 2, and then use the value used in obtaining the above (3) roundness ratio. Obtain the calculated long diameter and short diameter. For example, from the ratio of the diameter of a true circle with a certain target diameter (longer diameter=shorter diameter) to the above-mentioned long diameter, and the ratio of the diameter of the true circle to the above-mentioned short diameter, the irradiation mark can be used to determine the degree to which the irradiation mark matches the true circle. Take the form. The degree of coincidence adopts a value such that the maximum becomes 1 and the minimum becomes 0. When the value of the coincidence degree is 1, the shape of the irradiation mark is consistent with the shape of a true circle, which means that the irradiation mark is the intended shape, that is, the shape obtained when the laser beam 2 is normal. The laser processing device 100 outputs abnormalities as long as the obtained shape parameters are not within the normal range. On the other hand, the laser processing apparatus 100 determines that the laser beam 2 is normal as long as the shape parameter of the irradiation mark 20 falls within the normal range.

FIGS. 2 to 4 are diagrams schematically showing the irradiation of the laser beam 2 and the imaging of the irradiation mark by the camera 8 when the laser processing device 100 is used to perform abnormality detection of the laser beam 2. Fig. 2 is a diagram showing that a horseshoe-shaped irradiation mark 20 is formed when the laser beam 2 emitted from the laser oscillator 1 is irradiated on the workpiece 5b. As shown in the irradiation trace in Figure 2, when the laser beam 2 is abnormal, the laser beam 2 is condensed by the lens 4b and the focus position 10 is the position defocused from the surface of the workpiece 5b. , Form a horseshoe-shaped irradiation mark 20. Then, the irradiation mark 20 is moved below the camera 8, and the irradiation mark 20 is captured by the camera 8 to obtain an image. When image processing is performed on the horseshoe shape in Figure 2, (2) the diameter is relatively large, and (3) the true circle rate is relatively low compared to the normal state.

Fig. 3 shows that when the laser beam 2 emitted from the laser oscillator 1 is irradiated on the workpiece 5b, a donut-shaped irradiation mark 20 is formed. As shown in the irradiation trace in Fig. 3, when the laser beam 2 has an abnormality, when the laser beam 2 is condensed by the lens 4b and the position defocused from the surface of the workpiece 5b is taken as the focal position 10, the beam is irradiated, A donut-shaped irradiation mark 20 is formed. Then, the irradiation mark 20 is moved below the camera 8, and the irradiation mark 20 is captured by the camera 8 to obtain an image. When image processing is performed on the doughnut shape in Figure 3, (2) the diameter is relatively large, and (4) the degree of coincidence is relatively low compared to normal.

Fig. 4 shows that when the beam diameter and beam profile of the laser beam 2 are not abnormal, a substantially circular irradiation mark 20 is formed when the laser beam 2 is irradiated on the workpiece 5b. As shown in FIG. 4, when the laser beam 2 is condensed by the lens 4b and the beam is irradiated with the position defocused df from the surface of the workpiece 5b as the focal position 10, a substantially circular irradiation mark 20 is formed. Then, the irradiation mark 20 is moved to the position of the camera 8, and the irradiation mark 20 is captured by the camera 8 to obtain an image.

It is determined whether or not the value of the shape parameter measured from the image obtained by imaging the irradiation trace 20 by the camera 8 is included in the preset data range, thereby enabling detection of the abnormality of the laser beam 2. That is, as long as the work of irradiating the beam at the defocus position on the workpiece 5b shown in FIGS. 2 to 4 is integrated into the daily pre-adjustment work, even if the laser beam 2 does not occur The output is low, and the abnormality of the laser beam 2 can still be detected by performing image processing on the acquired image of the irradiation mark 20. In addition, it may be configured to use two or more of the acquired plurality of shape parameters to determine whether the laser beam 2 is abnormal. In this way, the reliability of abnormality detection can be improved.

Next, the step sequence of the abnormality detection method of the laser beam 2 of the embodiment 1 will be described using FIG. 5. During the pre-adjustment operation before the laser processing starts, the laser processing device 100 operates the drive mechanism 7a, 7b according to the operation of the operator to move the stage 6 so that the laser irradiation head 4 is positioned in the area outside the processing The irradiation position on the workpiece 5b (step S110). Next, the irradiation conditions of the laser beam 2 are set (step S120). Next, the irradiation step will be described. In the irradiation step, the workpiece 5b is irradiated with the laser beam 2 (step S130), and after the irradiation, the laser beam 2 is stopped (step S140). Next, the imaging procedure will be described. In the imaging step, the laser processing apparatus 100 operates the driving mechanisms 7a and 7b according to the operator's operation to move the stage 6 so that the irradiation mark 20 formed on the workpiece 5b is positioned under the camera 8 (step S150), and The irradiation mark 20 is captured by the camera 8. Next, the measurement procedure will be described. In the measurement step, the shape parameter of the irradiation trace 20 is measured from the captured image of the irradiation trace 20 (step S160). Next, the determination procedure will be described. In the judgment step, it is judged whether the measured shape parameter is within the normal range (step S170). If it is not within the normal range, it is judged that the laser oscillator 1 is abnormal and the output is abnormal (step S180), and the process ends. In addition, if the shape parameter is within the normal range in step S170, it is determined that there is no abnormality in the laser beam 2 and the processing ends. In addition, in the abnormality detection method of this embodiment 1, although the above-mentioned flow is described, the order of each step can be appropriately exchanged. For example, after step S120 of setting irradiation conditions, step S110 of moving to the irradiation position is performed.

Fig. 6 is a graph obtained by plotting (2) diameter, which is the shape parameter of the irradiation trace 20 measured daily, with respect to time. The method of judging whether there is an abnormality in the laser beam 2 will be described with reference to FIG. 6. The conditions for irradiating the laser beam 2 to the workpiece 5b, such as the number of shots, the energy per shot, the defocus amount df, etc., are determined in advance as the irradiation conditions. In addition, the imaging conditions of the camera 8 and the processing conditions of the image processing device 9 and abnormality determination conditions based on shape parameters are also set in advance. The above settings are fixed and judge whether there is an abnormality. That is, the conditions will not change on a daily basis. In addition, (2) the normal range of the diameter is determined, that is, the upper limit value 30a and the lower limit value 30b are determined as reference values, which are set in the laser processing apparatus 100 in advance. Regarding the upper limit 30a and the lower limit 30b, for example, when the laser beam 2 is in a normal state, the workpiece 5b can be processed with the laser beam 2 several times, and the average value of the (2) diameter of the irradiation trace 20 can be calculated. Set (average value) ± 4 × (standard deviation). Set at a certain time, it means that the result of (2) the diameter of the irradiation scar 20 obtained by the image processing device 9 exceeds the upper limit 30a or falls below the lower limit 30b. At this time, the laser processing device 100 outputs an alarm to notify the operator of the abnormality. By performing as described above, it is possible to detect an early abnormality of the laser beam 2 and to stop the processing of the workpiece 5a at this point in time, so that the continuous production of defective products can be stopped. In addition, the reference system of (3) the roundness ratio and (4) coincidence degree can be, for example, a reference such as 90% or more. The normal range system has only a lower limit value 30b and no upper limit value 30a. In addition, the warning system may be configured to notify the operator through an alarm, or may be one that emits light through a lamp, as long as it uses a means that allows the operator to recognize the abnormality.

Anomaly detection can also be carried out by combining other shape parameters such as (3) true roundness and (4) coincidence degree. For example, it can also be performed by (2) diameter, (3) true roundness, (4) ) The degree of agreement is a method of issuing a warning when two or more values deviate from the reference value. By proceeding as described above, the reliability of abnormality detection can be improved. In some cases, the image showing the irradiation mark 20 captured by the camera 8 may be out of focus due to undulations on the surface of the workpiece 5b. At this time, when it is desired to perform abnormality detection only with the diameter of (2), the result of the image processing performed by the image processing device 9 will cause errors. Although the laser beam 2 is not abnormal, the measurement result deviates from the normal Possibility of scope. In order to prevent the situation as described above, from the viewpoint of reliability, it is preferable to use two or more shape parameters for judgment.

In addition, for other abnormality detection methods, even if the value of the shape parameter deviates from the reference value, the warning is not output, and the shape parameter is measured multiple times, and the abnormality detection can be performed by comprehensive judgment from the multiple measurement results. Methods. For example, it is also possible to repeat the irradiation of the laser beam 2 and the measurement of the irradiation trace 20, and output a warning if it deviates from the reference value three times in a row, or it may be configured to measure any one of the three values continuously measured. The deviation from the reference value is determined by the judgment of the operator in addition to the output of the warning.

In addition, when the output of the laser beam 2 is low, the (2) diameter obtained from the irradiation mark 20 becomes smaller. In the first embodiment, the lower limit value 30b is also set in (2) the diameter, so that the output drop of the laser beam 2 can also be detected.

That is, according to the laser beam abnormality detection method of this embodiment 1, in daily pre-adjustment operations, the laser beam 2 is defocused from the focal position 10 and irradiated on the workpiece 5b, and the irradiation trace 20 is measured. (2) diameter and (3) true circularity and (4) degree of coincidence, so that even in the case where the laser beam 2 is not recognized as having a low output, the laser beam 2 can still be abnormal Detection.

In addition, for the abnormality of the laser beam described in this embodiment, for example, it is known to provide CCD (Charge Coupled Device) and CMOS (Complementary metal-oxide-semiconductor; complementary metal oxide The beam analyzer of the semiconductor sensor measures the beam profile of the laser beam, thereby being able to detect the abnormality of the optical component. However, as long as the laser beam abnormality detection method of this embodiment is used, the abnormality of the laser beam can be detected without installing a beam analyzer in the laser processing device, so that the cost can be kept low.

Implementation type 2. As mentioned above, when an abnormality occurs in the laser beam 2, it may be recognized that there is an abnormality not only in the beam diameter but also in the beam profile. Regarding whether the beam profile is abnormal, ideally, it is better to judge by measuring the intensity distribution of the laser beam 2 with a beam analyzer. However, the configuration of a beam analyzer for each laser processing device 100 is open to discussion from a cost point of view. Hereinafter, in the second embodiment, a method for detecting an abnormality of the laser beam 2 performed by an analog beam analyzer will be described. That is, this method is a method of detecting abnormal beam profile of the laser beam 2 in an analog manner without using a beam analyzer. Specifically, the relevant shape parameters of the irradiation mark 20 formed when the laser beam 2 is irradiated on the workpiece 5b for pre-adjustment under a plurality of irradiation conditions are superimposed to simulate the result of the beam analyzer, and output the simulation result. In this way, the abnormality of the laser beam 2 is detected.

Figures 7 and 8 are diagrams schematically showing examples of the intensity distribution of the laser beam 2 measured by the beam analyzer. Figure 7 is a bird's-eye view, and Figure 8 is a contour map, that is, a contour map. In the first embodiment, the case where the laser beam 2 is irradiated to the workpiece 5b under a single irradiation condition has been described. That is, it can be said that an irradiation trace 20 corresponding to any one of the contour lines of the contour 40 shown in FIG. 8 is obtained. In the second embodiment, the laser beam 2 is irradiated to the workpiece 5b under two or more different irradiation conditions. That is, two or more contour lines in the contour 40 shown in FIG. 8 are obtained.

This implementation type 2 is described in detail. The work 5b is a resin substrate made of solder resist, acrylic resin, and the like as in the first embodiment. In the entire two or more irradiation conditions, the defocus amount df is set to the same value. On the other hand, the number of shots, the energy per shot, or both are set to values that are changed in each irradiation condition. For example, when there are two irradiation conditions, one is set as the first condition for high-strength machining of the workpiece 5b (increasing the number of shots or increasing the energy per shot), and the other is set to be low-strength machining for the workpiece 5b The second condition (reducing the number of shots or reducing the energy per shot). By the conditions as described above, two irradiation traces 20 with different (2) diameters are obtained, and two different contour lines are obtained from the two irradiation traces 20.

Figures 9 and 10 show that if the two obtained irradiation marks are overlapped, the results obtained by the beam analyzer can be simulated without using the beam analyzer. In Fig. 9, the centers of the two irradiation marks 20a and 20b are the same, and they overlap into concentric circles. Therefore, it can be seen that the intensity distribution of the laser beam 2 is rotationally symmetrical. On the other hand, in Fig. 10, the centers of the two irradiation marks 20a and 20b are not aligned and staggered. Therefore, it can be seen that the intensity distribution of the laser beam 2 is biased rather than rotationally symmetric. In this way, to detect the deviation of the intensity distribution of the laser beam 2, the (1) center of gravity coordinates of the irradiation marks 20a and 20b are measured, and the (1) center of gravity coordinates of the irradiation mark 20a and (1) the center of gravity coordinates of the irradiation mark 20b are calculated. Shift Δ. For example, when the deviation Δ exceeds a preset value, it is determined that the intensity distribution of the laser beam 2 is biased, and the laser processing apparatus 100 outputs a warning to notify the operator that the laser beam 2 is abnormal. When the laser beam 2 is irradiated to the workpiece 5b under three or more different irradiation conditions, the (1) center of gravity coordinates of the irradiation mark 20 formed under a certain condition and the (1) center of gravity coordinates of the irradiation mark 20 formed under another condition are calculated ( 1) The offset Δ of the center of gravity coordinate, and calculate the maximum value of the offset Δ among them. It may be configured that when the maximum value exceeds a preset value, it is determined that the intensity distribution of the laser beam 2 is biased, and the laser processing apparatus 100 outputs a warning to notify the operator of the abnormality.

That is, according to the abnormality detection method of the laser beam 2 of the present embodiment 2, the laser beam 2 is irradiated to the workpiece 5b under a plurality of irradiation conditions, and the offset Δ of the (1) center of gravity coordinates between the irradiation marks is respectively Calculated, thereby enabling abnormal detection performed by an analog beam analyzer.

In addition, the image processing device 9 can simultaneously measure (2) diameter, (3) roundness, and (4) degree of coincidence with (1) center of gravity coordinates. Therefore, in conjunction with the implementation pattern 1, the (2) diameter, (3) roundness and (4) coincidence degree are compared with the reference for the irradiation mark 20 formed under each irradiation condition. Thereby, it is possible to deal with various abnormalities in the intensity distribution of the laser beam 2 without increasing the inspection time, and it is possible to detect abnormalities with a high probability.

Regarding the abnormality detection method of the laser beam 2 in the second embodiment, the processing flow when the abnormality detection is performed using two irradiation conditions is described using Fig. 11. During the pre-adjustment before the start of laser processing, the laser processing device 100 operates the drive mechanisms 7a and 7b according to the operation of the operator to move the stage 6 so that the laser head 4 is positioned in the area outside the processing area. The first irradiation position on the workpiece 5b (step S210). Next, the irradiation condition of the laser beam 2 is set to the first irradiation condition (step S220). Next, the workpiece 5b is irradiated with the laser beam 2 (step S230) to form a first irradiation mark 20a, and after the irradiation, the laser beam 2 is stopped (step S240). Next, the laser processing apparatus 100 operates the drive mechanism 7b according to the operation of the operator to move the stage 6 so that the laser irradiation head 4 is positioned at the second irradiation position on the workpiece 5b belonging to the out-of-process area (step S250) . Next, the irradiation condition of the laser beam 2 is set as the second irradiation condition (step S260). The workpiece 5b is irradiated with the laser beam 2 (step S270) to form a second irradiation mark 20b, and after the irradiation, the laser beam 2 is stopped (step S280). Next, the laser processing apparatus 100 operates the driving mechanisms 7a and 7b according to the operator's operation to move the stage 6 so that the first irradiation mark 20a is positioned at the imaging position under the camera 8 (step S290), and the camera 8 The first irradiation trace 20a is captured, and the acquired image is processed by the image processing device 9 to measure the position of the center of gravity of the first irradiation trace 20a (step S300). Next, the laser processing apparatus 100 operates the drive mechanism 7b according to the operation of the operator to move the stage 6 so that the second irradiation mark 20b is positioned at the imaging position under the camera 8 (step S310), and the camera 8 The 2nd irradiation mark 20b is imaged, and the acquired image is processed by the image processing device 9 to measure the position of the center of gravity of the 2nd irradiation mark 20b (step S320). Next, the offset Δ between the measured coordinates of the center of gravity is calculated (step S330). Next, it is determined whether the offset Δ exceeds a preset value (step S340), and if it exceeds, the laser beam 2 is set as an abnormality and an abnormality is output (step S350), and the process ends. In addition, if the offset Δ does not exceed the preset value in step S340, it is determined that there is no abnormality in the laser beam 2 and the processing ends. In addition, as explained in the first embodiment, the feature of this abnormality detection method is to perform abnormality determination based on imaging information before performing abnormality determination of the output of the laser oscillator.

Implementation type 3. Figures 12 and 13 are examples of measuring the height of the pulse waveform of the laser beam 2 with an oscilloscope using a photodetector. Figure 12 shows the situation when the output of the laser beam 2 is normal. Fig. 13 shows the situation when the laser beam 2 does not obtain a sufficient output at the beginning of the oscillation of the laser oscillator 1. In addition, in the laser oscillator 1 that converts the wavelength of the oscillated laser beam into the second harmonic and the third harmonic, as the wavelength conversion crystal deteriorates, there will be A situation where sufficient output cannot be obtained at the beginning of oscillation. In a thermal sensor generally used to measure the energy of the laser beam 2, since there is a delay when the measured value rises, it is impossible to measure the laser beam at the beginning of the oscillation. Output. Therefore, the abnormality of the laser beam 2 cannot be detected in the situation shown in FIG. 13.

In this case, the method of (2) measuring the diameter of the irradiation trace 20 shown in Embodiment 1 can also be used to detect abnormalities. However, the laser beam 2 has a high processability on the resin substrate, and the resin substrate is used for the workpiece 5b for adjustment. Even if the laser output is low at the beginning of the laser oscillation, the laser beam 2 can still be applied to the resin substrate well. For processing. Therefore, even if the processing results of the laser beam 2 when the output is normal and when the output is low are compared, the difference in the shape of the irradiation mark is small, and it is difficult to determine whether it is normal or abnormal. Therefore, in the third embodiment, a double-sided copper-clad laminate with copper foils provided on both sides of a resin substrate is used to perform abnormality detection of the laser beam 2.

The work 5b for pre-adjustment will be described in detail. Figure 14 shows the cross-sectional structure of the double-sided copper clad laminate. The double-sided copper clad laminate is a substrate with copper foils 50a on both the front and back of the resin substrate 50b. The double-sided copper clad laminate can be produced by attaching the copper foil 50a to the resin substrate 50b. Since the double-sided copper clad laminate is provided with a metal layer on the resin substrate 50b, the workability of the metal layer on the surface by the laser beam 2 is reduced. That is, the laser output system required for processing the workpiece 5b by the laser beam 2 is improved. In other words, regarding the threshold of output that enables laser processing, the double-sided copper clad laminate is higher than the resin substrate. When the output of the laser beam 2 decreases due to the deterioration of the wavelength conversion crystal as described above, the laser beam 2 does not penetrate the copper foil 50a as the output decreases. Therefore, by determining whether the laser beam 2 has successfully penetrated the copper foil 50a, it is possible to clearly determine the change in the laser output.

The specific anomaly detection method is explained. In this embodiment 3, the laser beam 2 is irradiated with the surface of the workpiece 5b as the focal position 10. In addition, the irradiation conditions are set in advance so that the output becomes equal to or higher than the output of the copper foil 50a whose laser beam 2 can barely penetrate the surface of the workpiece 5b. Regarding the setting conditions, for example, if the energy of each shot of the laser beam 2 is 50 μJ/shot, and the laser beam 2 penetrates the copper foil 50a at 20 shots (repetition frequency: 100 kHz), this setting is performed. That is, the conditions are set in advance: when the output of the laser beam 2 is normal, the laser beam 2 can penetrate the copper foil 50a, but if the output of the laser beam 2 is low at the beginning of the laser oscillation, the copper cannot pass through. Foil 50a. Regarding the condition that it becomes impossible to penetrate the copper foil 50a, for example, the following condition can be adopted: it is specified in advance that the output value that will be determined as abnormal when the output of the laser beam 2 is low at the beginning of laser oscillation, and when it is lower than the output value, The laser beam 2 cannot penetrate the copper foil 50a. When the irradiation mark when the copper foil 50a is not penetrated is captured and the obtained image is image-processed by the image processing device 9, then (1) the coordinates of the center of gravity, (2) the diameter, (3) the roundness, (4) The consistency cannot be measured, so an error is generated. When receiving the error, the laser processing device 100 outputs a warning to notify the operator that the laser beam 2 is abnormal. In addition, the judgment of whether it is abnormal does not necessarily need to be performed by capturing the irradiation mark with the camera 8 and processing the captured image by the image processing device 9. It may also be constituted by the operator by visual inspection. Check the irradiation mark to determine whether there is a through metal layer. In addition, the metal system provided on both the front and back surfaces of the resin substrate 50b does not need to be copper as long as it can perform the above-mentioned detection method, but the double-sided copper clad laminate is easy to obtain and inexpensive.

That is, according to the abnormality detection method of the laser beam 2 of the present embodiment 3, the workpiece 5b adopts a double-sided copper clad laminate to determine whether the copper foil 50a is successfully penetrated, thereby enabling the laser to be performed at the beginning of the oscillation. Detection of abnormal output of laser beam 2 with low output. [Industrial use possibility]

As mentioned above, the laser beam abnormality detection method and laser processing device of the present invention are suitable for laser processing of workpieces, and suitable for micro laser processing in which laser light is irradiated to the workpiece to perform hole processing. Laser processing performed by the device.

1: Laser oscillator 2: Laser beam 3: mirror 4: Irradiation head 4a: Scanning mirror 4b: lens 5a: processed objects 5b: Workpiece for front adjustment 6: Stage 6a: Processing area 6b: Out-of-processing area 7a, 7b: drive mechanism 8: Camera 9: Image processing device 10: Focus position 20: Irradiation marks 20a: Irradiation marks 20b: Irradiation marks 30a: upper limit 30b: lower limit 40: contour (contour line) 50a: Copper foil 50b: Resin substrate 100: Laser processing device df: Defocus amount S110 to S180, S210 to S350: steps Δ: offset

Fig. 1 is an example of a laser processing apparatus for explaining an implementation type of an abnormality detection method of a laser beam. Figure 2 is a diagram showing a horseshoe-shaped irradiation mark when the beam profile of the laser beam is abnormal. Fig. 3 is a diagram showing a donut-shaped irradiation mark when the beam profile of the laser beam is abnormal. Figure 4 is a diagram showing a circular irradiation mark when the beam profile of the laser beam is normal. Fig. 5 is a flow chart showing the flow chart of the laser beam abnormality detection method of implementation type 1. Figure 6 is a diagram showing an example of the history of the diameter of the irradiation scar measured daily. Figure 7 is a bird's eye view showing an example of measurement of the intensity distribution of a laser beam by a beam profiler. Figure 8 is a contour diagram showing a measurement example of the intensity distribution of a laser beam by a beam analyzer. Fig. 9 is a diagram illustrating the measurement method of the analog beam analyzer that superimposes the intensity distributions represented by two irradiation marks in the second embodiment (the intensity distribution is rotationally symmetric). Fig. 10 is a diagram illustrating the measurement method of the analog beam analyzer that superimposes the intensity distributions represented by two irradiation marks in the second embodiment (the intensity distribution is biased). Fig. 11 is a flowchart showing the flow of the laser beam abnormality detection method of embodiment 2. Figure 12 is an example of measuring the height of the pulse waveform of the laser beam when the laser beam is normal by using a photo detector and an oscilloscope. Fig. 13 is an example of measuring the height of the pulse waveform of the laser beam when the laser beam does not obtain a sufficient output at the beginning of the oscillation of the laser beam using a photodetector and an oscilloscope. Figure 14 is a diagram showing the cross-sectional structure of the double-sided copper clad laminate.

2: Laser beam

4b: lens

5b: Workpiece for front adjustment

8: Camera

10: Focus position

20: Irradiation marks

Claims (14)

A method for detecting anomalies of a laser beam is a method of detecting anomalies of a laser beam in a laser processing device equipped with a laser oscillator that emits the laser beam, The laser beam abnormality detection method has the following steps: The irradiating step is to irradiate the pre-adjustment substrate placed outside the processing area on which the material to be processed by the laser beam is stored, with the laser beam defocused from the surface of the pre-adjustment substrate ； The imaging step is to obtain imaging information by imaging the irradiation marks on the pre-adjustment substrate formed by the irradiation step by imaging means; The measuring step is to measure the shape parameter related to the shape of the irradiation trace based on the imaging information obtained by the aforementioned imaging step; and The judging step is to judge the laser beam as abnormal when the measurement result in the aforementioned measurement step exceeds the range indicating that the laser beam is normal. The laser beam abnormality detection method described in the first item of the patent application, wherein the measurement step is to obtain the shape parameter from the data group obtained from the contour of the shape of the irradiation mark, and the shape parameter includes the irradiation At least one of the coordinates of the center of gravity of the mark, the diameter of the irradiation mark, the roundness, and the degree of coincidence with the true circle with the target diameter. For the laser beam abnormality detection method described in item 2 of the scope of patent application, the aforementioned determination step is when the measurement results of two or more of the aforementioned shape parameters exceed the range indicating normality, it is determined as The laser beam is abnormal. For the laser beam abnormality detection method described in the first item of the patent application, the aforementioned shape parameters include the coordinates of the center of gravity of the irradiation mark, the diameter of the irradiation mark, the roundness ratio, and the distance between the true circle and the target diameter. Consistency The foregoing measurement step is to perform multiple measurements on the foregoing shape parameter; The foregoing determination step is to determine that the laser beam is abnormal when, among the measurement results of the foregoing shape parameter measured a plurality of times, the laser beam exceeds the range indicating that it is normal. For the laser beam abnormality detection method described in the second item of the patent application, the aforementioned shape parameters include the coordinates of the center of gravity of the irradiation mark, the diameter of the irradiation mark, the roundness ratio, and the distance between it and the true circle with the target diameter. Consistency The foregoing measurement step is to perform multiple measurements on the foregoing shape parameter; The foregoing determination step is to determine that the laser beam is abnormal when, among the measurement results of the foregoing shape parameter measured a plurality of times, the laser beam exceeds the range indicating that it is normal. For the laser beam abnormality detection method described in item 3 of the scope of patent application, the aforementioned shape parameters include the coordinates of the center of gravity of the irradiation mark, the diameter of the irradiation mark, the roundness ratio, and the distance between the true circle and the target diameter. Consistency The foregoing measurement step is to perform multiple measurements on the foregoing shape parameter; The foregoing determination step is to determine that the laser beam is abnormal when, among the measurement results of the foregoing shape parameter measured a plurality of times, the laser beam exceeds the range indicating that it is normal. The laser beam abnormality detection method described in any one of the claims 1 to 6, wherein the focus position of the defocused state is located on the surface of the pre-adjustment substrate and the laser beam Between the condenser lenses. According to the laser beam abnormality detection method described in item 7 of the scope of patent application, the distance from the focal position in the defocused state to the surface of the pre-adjustment substrate is 1 mm to 5 mm. The method for detecting anomaly of a laser beam as described in any one of items 1 to 6 of the scope of the patent application, wherein the aforementioned irradiation step is to adjust the aforementioned laser beam under two or more different irradiation conditions. The step of irradiating the substrate; The aforementioned imaging step is a step of obtaining imaging information from a plurality of irradiation marks formed by the aforementioned two or more different irradiation conditions; The aforementioned measurement step is a step of separately measuring the coordinates of the center of gravity from the camera information of the aforementioned plural irradiation marks; The foregoing determination step is to determine that the laser beam is abnormal when the distance between any two of the center of gravity coordinates of the plurality of irradiation marks exceeds the range indicating that the laser beam is normal. According to the laser beam abnormality detection method described in claim 7, wherein the aforementioned irradiation step is a step of irradiating the aforementioned pre-adjustment substrate with the aforementioned laser beam under two or more different irradiation conditions; The aforementioned imaging step is a step of obtaining imaging information from a plurality of irradiation marks formed by the aforementioned two or more different irradiation conditions; The aforementioned measurement step is a step of separately measuring the coordinates of the center of gravity from the camera information of the aforementioned plural irradiation marks; The foregoing determination step is to determine that the laser beam is abnormal when the distance between any two of the center of gravity coordinates of the plurality of irradiation marks exceeds the range indicating that the laser beam is normal. According to the laser beam abnormality detection method described in item 8 of the scope of patent application, the aforementioned irradiation step is a step of irradiating the aforementioned pre-adjustment substrate with the aforementioned laser beam under two or more different irradiation conditions; The aforementioned imaging step is a step of obtaining imaging information from a plurality of irradiation marks formed by the aforementioned two or more different irradiation conditions; The aforementioned measurement step is a step of separately measuring the coordinates of the center of gravity from the camera information of the aforementioned plural irradiation marks; The foregoing determination step is to determine that the laser beam is abnormal when the distance between any two of the center of gravity coordinates of the plurality of irradiation marks exceeds the range indicating that the laser beam is normal. A method for detecting anomalies of a laser beam is a method of detecting anomalies of a laser beam in a laser processing device equipped with a laser oscillator that emits the laser beam, The laser beam abnormality detection method has the following steps: In the irradiation step, a pre-adjustment substrate provided with a metal layer on the resin layer is arranged outside the processing area of the material to be processed by the aforementioned laser beam, and the surface of the pre-adjustment substrate is used as Irradiate the laser beam in the state of the focus position; The imaging step is to obtain imaging information by imaging the irradiation marks on the pre-adjustment substrate formed by the irradiation step by imaging means; The measuring step is to measure the shape parameter related to the shape of the irradiation trace based on the imaging information obtained by the aforementioned imaging step; and The judging step is to judge that the output of the laser beam is abnormal when the measurement result of the measuring step is that the metal layer is not penetrated by the laser beam. The laser beam abnormality detection method described in item 12 of the scope of patent application, wherein the aforementioned pre-adjustment substrate is a double-sided copper clad laminate. A laser processing device is a laser processing device provided with a laser oscillator that emits a laser beam, and the aforementioned laser processing device includes: The processing stage is to store the processed materials processed by the aforementioned laser beam; The imaging means is on the aforementioned processing stage, and irradiates the aforementioned thunder at a focal position in a state defocused from the surface of the aforementioned pre-adjustment substrate, which is set outside the processing area where the material to be processed is processed. The beam captures the irradiation marks formed on the aforementioned pre-adjustment substrate to obtain imaging information; The measuring means is to measure the shape parameters related to the shape of the aforementioned irradiation trace based on the aforementioned camera information; and The judgment means is to judge that the laser beam is abnormal when the measurement result of the aforementioned measurement means exceeds the range indicating that the laser beam is normal.

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