JP2013111629A - Correction method for laser irradiation position and laser processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a correction method for a laser irradiation position capable of finally performing accurate correction of a laser irradiation position by quantitatively understanding a tendency of accuracy deterioration at simple measuring concerning to accuracy deterioration of the laser irradiation position when a shipped laser processing system starts up again after it is arrived.SOLUTION: In the correction method for a laser irradiation position used in the laser processing system for processing by dividing into a plurality of processing areas, the method includes a step of preparing a plurality of test processing points on diagonal lines per respective processing areas at equal intervals and processing the test processing points by performing correction on the basis of predetermined first correction data; a step of measuring actual processing locations of the test processing points; a step of calculating an amount of gaps on planes of positions to be processed and actually processed positions on two axes crossed at a right angle; a step of calculating shift components and inclined components of the amount of gaps each two axes per each processing area; and a step of setting second correction data by taking correction information per each processing area calculated so as to cancel the shift components and the inclined components into the first correction data.

Description

  The present invention relates to a laser processing apparatus for processing a thin plate-like workpiece by irradiating a laser, and more particularly to a method for correcting the processing position.

  In recent years, there has been a demand for downsizing and weight reduction of electronic devices. In order to realize this, a laser processing apparatus equipped with an optical positioning device and processing an object using light such as laser light or visible light is often used. For example, in a laser processing apparatus for a printed circuit board, the printed circuit board is irradiated with laser light to perform IVH (inner via hole) drilling, which is an interlayer connection circuit of the multilayer printed circuit board.

  The prior art will be briefly described with reference to the drawings. As shown in FIG. 8, a pair of galvano scanners and an fθ lens 906 are arranged in the optical path of a laser beam 902 emitted from a laser oscillator 901, and a workpiece 905 is mechanically driven to mechanically drive a workpiece. A laser beam is irradiated to a desired position 907.

  In the processing operation of this laser processing apparatus, a long workpiece as shown in FIG. 9 is set to be divided into rectangular processing areas. The laser beam is positioned in each processing area by controlling the galvano scanner, and the processing range by the galvano scanner is driven by driving the X-axis stage 908 and the Y-axis stage 909 each time processing of one rectangular area is completed. Next, the next rectangular area is moved to process the entire long workpiece 907.

  In general, in such laser processing, there is a problem that a deviation occurs between a position where the laser beam is to be irradiated and a position where the laser beam is actually irradiated, and the accuracy of the laser processing is deteriorated. Causes of positional deviations are due to the accuracy of parts and assembly, pincushion distortion caused by the geometric arrangement of mirrors of the galvano scanner, and linearity errors in the optical design of the fθ lens. It has been found that the resulting geometric distortion occurs.

  Therefore, as an example of the prior art, a technique for correcting the deviation of the laser beam irradiation position is shown. A test substrate is prepared, and holes are formed by irradiating a laser beam to coordinate points arranged in a lattice pattern at equal intervals in a square region designed on the substrate. If there is no misalignment of the laser beam irradiation position, the processed holes should exist exactly at the square lattice points. However, since the laser irradiation positions are actually shifted, the arrangement of the holes is distorted.

  By measuring the position of the processed hole and comparing it with the position of the coordinate point to be processed, the deviation of the laser beam irradiation position at each lattice point can be obtained. The deviation of the laser beam irradiation position at the intermediate position of each lattice point can be obtained by interpolation calculation of the deviation at adjacent lattice points.

  The deviation of the irradiation position of the laser beam is input as correction information to a control unit that controls a galvano scanner or the like provided in the laser processing apparatus, and the laser beam irradiation is performed when the workpiece is actually processed. The position is corrected on the control data, and the laser is accurately irradiated at the target position to perform high-precision processing (see, for example, Patent Document 1).

  Alternatively, as a different example of the conventional technique for correcting the deviation of the laser beam irradiation position, the deviation amount at each coordinate of the lattice point where the positional deviation is measured is not directly used as correction information, but the deviation amount is calculated over the entire processing range. A quadratic function is set, a coefficient of the quadratic function is obtained from the amount of deviation of a large number of lattice points, and the deviation of the irradiation position of the laser beam is used as correction information for the quadratic function after calculating the coefficient (for example, , See Patent Document 2).

  As another example of the conventional technique for correcting the deviation of the irradiation position of the laser beam, the deviation of the laser beam irradiation position at the intermediate position of each lattice point can be interpolated from the deviation amount at each coordinate of the lattice point where the positional deviation is measured. Although it is the same in the point to obtain | require, there exists what devised to reduce the number of the lattice points which irradiate a laser beam experimentally by performing interpolation by a spline (for example, refer patent document 3).

  As another example of the conventional technique for correcting the deviation of the irradiation position of the laser beam, the amount of change in elongation is measured with a machining pattern that mainly measures the outer circumference of the machining range against the positional deviation over time caused by the laser beam. Some measure and rewrite the original positional deviation correction information (see, for example, Patent Document 4).

JP-A-8-174256 JP 2002-316288 A Japanese Patent Laid-Open No. 10-301052 JP 2003-126980 A

  Certainly, according to the prior art described in the literature as described above, after the assembly of the laser processing apparatus, a sufficient amount of time and effort is taken to perform experimental processing and position measurement, and the correction information of the deviation amount based on the measurement result As long as machining is performed under the same conditions, laser machining can be performed with high positional accuracy.

  However, a factory that manufactures a laser processing apparatus as a manufacturer and a factory that processes a substrate as a user of the laser processing apparatus are generally different.

  FIG. 10A shows a distribution of positional deviation of laser irradiation of a laser processing apparatus (laser drilling apparatus) before factory shipment. This data is data obtained after completion of the apparatus by obtaining correction information with a test substrate, and performing hole processing while performing position correction on the test substrate again based on this correction information.

  Looking at this graph, it can be seen that machining with very small variations and high accuracy has been achieved.

  On the other hand, FIG. 10B shows the distribution of positional deviation after the same apparatus is shipped from the factory, installed in the user's factory, and started up. This data is acquired by correcting the position using the same correction information using the test substrate having the same specifications as the measurement of FIG. 10A and drilling holes at the same processing position.

  Comparing the two graphs shown in FIGS. 10 (a) and 10 (b), if correction is made using positional deviation data using a test substrate as correction information, the laser irradiation is sufficiently accurate before shipping the apparatus. However, after the device is shipped, when it is installed in the user's factory and restarted, it can be seen that the accuracy is deteriorated even if the same correction is performed. The cause is a disturbance of accuracy that cannot be controlled even if meticulous attention is paid to the transportation and installation of precision machinery, such as deterioration of the accuracy of equipment during work for transportation and transportation, and the influence of the environment after installation. Is estimated to be affected.

  Of course, after starting up the device at the installation location, it is possible to ensure accuracy by acquiring the same correction information as before shipping and correcting it, but at the user's factory, sufficient time and effort are required as before shipping. Cannot be used to test.

  For this reason, there is a method for correcting the laser irradiation position used in a laser processing apparatus that can finally perform highly accurate correction while quantitatively grasping the tendency of accuracy deterioration by simple measurement and utilizing the first correction information acquired before shipment. It was sought after.

  In order to solve the above-described problems, a laser irradiation position correction method according to the present invention includes a galvano scanner, an fθ lens, and a table on which a workpiece is placed and movable in two horizontal axes. A laser irradiation position correction method used in a laser processing apparatus that performs processing by dividing into a plurality of rectangular processing areas, wherein a plurality of test processing points arranged at equal intervals on a diagonal line are set for each processing area, A step of machining a test machining point by performing correction based on the set first correction data, a step of measuring an actual machining position of the test machining point, and a position to be machined and an actual machining position Calculating a shift amount on the plane of the position at two orthogonal axes, calculating a shift component and a tilt component of the shift amount for each of the processing areas, and the shift component. And correction information for each machining area calculated so as to cancel the inclination component is added to the first correction data to obtain second correction data. In this method, position correction is performed using correction data.

  By the above laser irradiation position correction method, we can quantitatively grasp the tendency of accuracy deterioration with simple measurement against the deterioration of laser irradiation position accuracy when the laser processing device is restarted after shipment. It is possible to finally perform highly accurate correction while using the correction information.

Schematic configuration diagram showing the configuration of a laser processing apparatus according to an embodiment of the present invention The top view which shows an example which set the some rectangular process area of this invention to the workpiece The figure which shows the position shift of the laser irradiation of one process area of this invention The figure which shows the test processing point set to each processing area which is the characteristics of this invention The graph which shows the amount of position shift at the time of processing before shipment at the test processing point of the present invention Graph showing the amount of misalignment when machining after installation at the test machining point of the present invention The graph which expands and shows the amount of position shift of one processing area of the present invention Schematic configuration diagram of a laser processing apparatus according to the prior art Schematic diagram showing a state in which a workpiece according to the prior art is divided into a plurality of rectangular areas A graph that quantitatively explains the problems of conventional technologies

(Embodiment 1)
One example of an embodiment of a laser processing apparatus of the present invention and a laser irradiation position correcting method used in the laser processing apparatus will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a configuration of a laser processing apparatus 100 according to the present embodiment.

  A laser 102 is emitted from a laser oscillator 101, and a direction is changed by a mirror 103 to a predetermined direction in which an optical system is provided. A lens 104 for adjusting the density (laser diameter) of the laser 102 is disposed in the traveling direction of the laser 102, a mask 105 for shaping the shape of the laser 102 that has passed through the lens 104, and the mask 105. The iris 106 for suppressing the miscellaneous light of the laser 102 is disposed.

  The laser 102 that has passed through the iris 106 includes a galvano mirror (X axis) 109 for swinging in the X axis direction and a galvano mirror (Y axis) 110 for swinging the laser 102 reflected by the galvanometer mirror 109 in the Y axis direction. Positioned. Further, the laser 102 reflected by the galvanometer mirror 110 is condensed by the fθ lens 107 and irradiated to the processing point of the workpiece 113.

  Here, the controller 108 controls the galvanometer mirrors 109 and 110 and the laser oscillator 101. Further, the processing table 111 is configured to be movable in two directions, the X direction and the Y direction, and the workpiece 113 is placed on the processing table 111.

  The operation of the laser processing apparatus configured as described above will be described.

  FIG. 2 is a plan view showing an example of setting a plurality of rectangular machining areas 200 on the workpiece. In the present embodiment, a case will be described in which the rectangular processing area 200 is a 30 mm square area, and five are set in the X-axis direction and four in the Y-axis direction of the drawing coordinates. Of course, depending on the scale of the apparatus, the number of rectangular processing areas may be different from this example, and the size of the processing area may be 50 mm square or 70 mm square.

  In FIG. 2, the numbers assigned to the respective processing areas 200 indicate the order of processing, and indicate that the processing is performed in the order of the arrows in the drawing. In the following description, for convenience, the numbers in the drawing are used to refer to the “first processing area” and the “second processing area” and the respective processing areas.

  After the workpiece 113 is placed on the processing table 111, the first processing area is positioned under the fθ lens 107 by the movement of the processing table 111.

  Next, based on the processing data of the first processing area 201, the galvanometer mirrors 109 and 110 are rotated and positioned, and the laser 102 is emitted from the laser oscillator 101 in synchronization with a predetermined timing. The laser 102 is reflected by the galvanometer mirrors 109 and 110, is condensed on the workpiece 113 by the fθ lens 107, and a hole is drilled at a predetermined position in the region. Regarding the processing position of one processing area 200, the processing table 111 does not move, and is processed only by the positioning operation of the galvanometer mirrors 109 and 110.

  When the processing by laser irradiation to the first processing area 201 is completed, the processing table 111 is moved, and the second processing area 202 is positioned below the fθ lens 107. Then, similarly to the above, drilling is performed at a predetermined position in the region based on the processing data of the second processing area 202.

  Similarly, the movement of the processing table 111 and the drilling processing in the processing area by positioning and condensing the laser 102 by the galvanometer mirrors 109 and 110 and the fθ lens 107 are repeated, and the processing of all the set processing areas 200 is completed. .

  After the processing is completed, the processing table 111 is moved, and the processed workpiece 113 is stored in a predetermined place.

  FIG. 3 is a diagram showing a positional deviation of laser irradiation in a certain processing area 200.

  A test substrate is prepared as the workpiece 113. A dry film having a thickness of 800 μm is used as an example of a test substrate. A grid with an equal pitch is provided for each of a plurality of machining areas 200, and holes are drilled at the intersections. If the pitch of the lattice pattern is 1 mm and the processing area is 30 mm square, 31 × 31 lattice points can be set.

  In FIG. 3, the processing area is drawn with a grid that is divided into 8 × 8 because it becomes complicated. As for the hole diameter, a small-diameter hole is obtained with a stable machining diameter and a small measurement error. In this embodiment, a hole having a diameter of 60 μm is processed.

  In FIG. 3, as shown in a partially enlarged view, the vector 132 in the figure indicates this positional deviation, and the amount of positional deviation is measured quantitatively in the two axial directions (X-axis and Y-axis) of the plane. can do. The vector in the figure shows the positional deviation amount 133 in the X-axis direction and the positional deviation amount 134 in the Y-axis direction.

  The cause of this misalignment is a combination of the mismatch between the axis scanned by the galvanometer mirror and the axis moving by the processing table, the inclination of the fθ lens, aberration, distortion, accuracy of other equipment, and accuracy due to assembly. Yes.

  However, if these factors are determined, the error is reproduced. Therefore, the positional deviation amount is quantitatively measured on the test substrate, and the position coordinates of the processing data (drill data) are set so as to cancel it. If corrected, the actual machining position can be matched with the required accuracy to the position to be machined.

  As the correction information for correcting the position coordinates, the deviation between the X-axis direction and the Y-axis direction is stored in association with the coordinates of each lattice point, and the deviation between the lattice points can be obtained by interpolation. .

  Alternatively, the amount of deviation in the X-axis direction and the amount of deviation in the Y-axis direction are each expressed by a function that uses the machining area number and the XY coordinates in the machining area as arguments, and the coefficients of the function are obtained by machining the test substrate. Coefficients may be obtained from the measured values by multiple regression analysis and stored in the form of functions.

Since the interpolation can be regarded as a function in a broad sense, the position where the nth machining area is to be machined is (x, y), the corrected position after canceling the deviation is (x ′, y ′), a specific If the function is f and g,
x ′ = f (n, x, y)
y ′ = g (n, x, y)
Can be expressed.

  In this application, using this relational expression, the corrected (x ′, y ′) is used as control data for the positioning operation of the galvanometer mirror for the position (x, y) where the drill data is to be processed. This is referred to as one correction. That is, the first correction data indicates quantitative information for canceling the “positional deviation when the workpiece is processed without correction” after the apparatus is completed.

  It should be noted that the number of grid points for measuring the deviation amount on the test substrate may be determined according to the required accuracy, and is not necessarily limited to processing and measuring all the grid points.

  FIG. 4 is a diagram showing test machining points set in each machining area, which is a feature of the present invention.

  In FIG. 4, a plurality of test machining points 142 arranged at equal intervals on a diagonal line 141 are set for each machining area 200. In this figure, nine points are set to divide the line segment connecting the origin 140 and the diagonal of the origin 140 into eight equal parts for the sake of complexity.

  In the present embodiment, 31 points that divide the diagonal line passing through the origin 140 into 30 equal parts at a pitch of 1 mm in both the X-axis direction and the Y-axis direction are set in a rectangular processing area 200 of 30 mm square. These points are set as test processing points on the test substrate.

  In an experiment conducted by the inventor, 31 test processing points arranged at equal intervals on the diagonal line with a pitch of 1 mm in all the 20 processing areas were set at a total of 620 locations, and the first correction set in advance. The test machining point was drilled with correction based on the data.

  The test substrate used was a dry film having a thickness of 800 μm, and the diameter of the hole processing was 60 μm. As for the processing order, 31 diagonal processing points were sequentially processed from the origin to the diagonal, and the processing was performed from the first processing area to the 20th processing area in order.

  After processing, the position of the actually processed holes was measured in the order of processing using a precision image measuring machine (two-dimensional projection length measuring machine), and the displacement was calculated for the X-axis direction and the Y-axis direction. .

  FIG. 5 is a graph of the amount of deviation measured before shipping after assembling and adjusting the laser processing apparatus using 620 test processing points. The horizontal axis is 1 to 620 in the order of processing. FIG. 5A shows the amount of deviation in the X-axis direction, and FIG. 5B shows the amount of deviation in the Y-axis direction.

  By performing the first correction, a slight shift can be seen, but there is little variation in the X-axis direction and the Y-axis direction, and very good machining accuracy can be reproduced.

  Next, FIG. 6 shows the positional deviation distribution of the same apparatus after the apparatus is shipped from the factory and the apparatus is started up after being installed in the user's factory. This data is obtained by performing the same first correction using a test substrate having the same specifications as the measurement of FIG. 5, drilling a hole at the same processing position, and obtaining a deviation amount. FIG. 6A shows the amount of deviation in the X-axis direction, and FIG. 6B shows the amount of deviation in the Y-axis direction.

  It can be seen from FIG. 6 that the position accuracy is clearly worse than before shipment. Also, there is a tendency for the accuracy to deteriorate, and the graph looks like a saw blade. This is because the processing pitch is shifted in each processing area 200.

  If the cause of the estimation is briefly considered from the tendency of the deviation amount that can be read from the graph, it is assumed that the installation variation due to the installation of the processing table, the head including the fθ lens and the galvanometer mirror is affected.

  When the positions of the processing table, the fθ lens, and the galvanometer mirror are deviated from the initial positions, the processing pitch changes. From the point of time when the first correction is made before shipment, a graph is shown in which the pitch increases as the pitch increases, and the pitch decreases as the pitch decreases. Since this is repeated for each processing area, it is estimated that the graph is like a saw blade. In addition, since the feeding accuracy of the machining table during movement of the machining area is also affected, the graph slightly fluctuates for each machining area.

  The above phenomenon is always reproduced as a trend, although the direction and amount of tilt may change even when the apparatus is different. In addition, once installed and started up, the direction and amount of tilt are always reproduced.

  FIG. 7 is a graph obtained by extracting and enlarging only the data in the eighth processing area of FIG. It is a graph (a) of the amount of deviation in the X-axis direction and a graph (b) of the amount of deviation in the Y-axis direction of the 218 to 248th machining orders. A processing point with a processing order of 218 corresponds to the origin in this processing area. Sequentially, the diagonal line of the machining area is machined at a pitch of 1 mm on the X axis and the Y axis, and the 248th is a diagonal machining point separated by 30 mm on the X axis and Y axis. Coordinates with respect to the origin of the test machining points are associated with the order of the test machining points and attached to the scale on the horizontal axis.

  In the graph, when a line segment is drawn by least square estimation with respect to 31 measured values, it can be seen that the amount of deviation which is a problem of the present invention is approximated by a straight line in this graph. The mathematical expressions of Δx and Δy in the graph are generalized equations of line segments obtained by least square estimation. This graph represents the amount of positional deviation of the eighth machining area, but is represented by (n) indicating the nth machining area in order to generalize the mathematical expression.

  In this way, when each calculated positional deviation amount is approximated by a straight line, as shown in FIG. 7, an inclination component (α1 and α2 in the figure) in which the deviation changes in proportion to the distance from the origin, Is a shift component that rises and falls on the graph (β1 and β2 in the figure), and it can be seen that the amount of deviation of the laser irradiation position after restart after shipping can be expressed.

When this is expressed by an equation, as shown in FIG.
Δx = α1 (n) · x + β1 (n)
Δy = α2 (n) · y + β2 (n)
Can be expressed.

  As shown in FIG. 4, the shift component and the tilt component of the shift amount can be easily and quantitatively acquired for each processing area as described above. This is because a plurality of test machining points arranged at equal intervals on the diagonal line are set for each machining area. Only after the idea of the test machining point can we grasp the characteristic tendency of the laser irradiation position deviation after restarting after shipment, and since only the machining point on the diagonal line is machined and measured, it requires few steps. Necessary data can be collected.

  At the same time, the calculation of “shift component” and “slope component” for each machining area for canceling the deviation amount is also processed at an equal pitch on the diagonal line. In addition, both a scientific calculator and a spreadsheet software that draws the graph can be easily obtained.

  As described above, since the deterioration of accuracy due to restarting can be quantitatively grasped for each processing area after the device is shipped, the calculated shift component and tilt component are taken into account to be canceled in the first correction data. If the second correction data is calculated and the laser irradiation position is corrected, the influence of the accuracy deterioration can be canceled.

If this is expressed using the functional equation shown in the explanation of the first correction,
x ″ = f (n, x, y) − (α1 (n) · x + β1 (n))
y ″ = g (n, x, y) − (α2 (n) · y + β2 (n))
It becomes.

  Using this relational expression, the corrected (x ″, y ″) is used as control data for the positioning operation of the galvanometer mirror for the position (x, y) where the drill data is to be processed. The second correction is referred to as a second correction.

  That is, the second correction information is a new correction quantitative information by adding correction data for each processing area calculated so as to cancel the shift component and the tilt component to the first correction data. It is what.

  In actual machining, if the laser irradiation position is corrected using the second correction data, laser machining can be performed with sufficiently high accuracy.

  Note that the coordinates of the test machining points set on the diagonal line of the machining area are set to an equal pitch, so that there is an effect that the inclination component can be visually discriminated immediately when graphed.

  Further, it is desirable that the pitch is a unit dimension in both the X-axis direction and the Y-axis direction. In this case, if the graph is drawn as shown in the present embodiment, the “shift component” and the “slope component” can be calculated as they are. In this case, the rectangular processing area is a square as shown in the present embodiment.

  As described above in detail, according to the present invention, a plurality of test machining points arranged at equal intervals on a diagonal line are set for each machining area, and correction based on first preset correction data is performed. By simply performing a simple test and measurement of machining the test machining point at the factory where the equipment was installed and restarted after shipment, the trend of deterioration in accuracy can be quantitatively grasped, and the first correction information acquired before shipment is The laser irradiation position can be finally corrected with high accuracy while being utilized.

  As described above, in the embodiment, specific numerical values are raised and the configuration, principle, consideration of the result of the experiment, and the like have been described. However, the application of the present invention is not limited to the above specific numerical values.

  The laser irradiation position correction method of the present invention is a method for quantitatively grasping the tendency of accuracy deterioration by simple measurement against the deterioration of the accuracy of the laser irradiation position when the laser processing apparatus is restarted after shipment. This makes it possible to perform high correction and is useful for a laser processing apparatus such as a laser drilling apparatus.

DESCRIPTION OF SYMBOLS 100 Laser processing apparatus 101 Laser oscillator 102 Laser 103 Mirror 104 Lens 105 Mask 106 Iris 107 f (theta) lens 108 Control controller 109 Galvano mirror (X axis)
110 Galvano mirror (Y axis)
111 Machining Table 113 Workpiece 200 Machining Area 201 First Machining Area 202 Second Machining Area 130 Position to be Machined 131 Actual Machining Position 132 Position Misalignment Vector 133 X-axis Direction Misalignment Amount 134 Y Axial misalignment 140 Origin point 141 Diagonal line 142 Test machining point

Claims (3)

A laser used in a laser processing apparatus including a galvano scanner, an fθ lens, and a table on which a workpiece is placed and movable in two horizontal axes, and which divides the workpiece into a plurality of rectangular processing areas. An irradiation position correction method,
Setting a plurality of test machining points arranged at equal intervals on the diagonal line for each machining area, applying a correction based on preset first correction data, and machining the test machining points;
Measuring the actual machined position of the test machining point;
Calculating the amount of deviation on the plane between the position to be machined and the actually machined position in two orthogonal axes;
Calculating a shift component and a tilt component of the deviation amount for each of the two axes for each processing area;
A step of adding correction information for each processing area calculated so as to cancel the shift component and the tilt component to the first correction data to obtain second correction data;
A method for correcting a laser irradiation position in which actual position correction is performed using the second correction data. The laser irradiation position correction method according to claim 1, wherein the processing area is a square, and a pitch of test processing points arranged at equal intervals on a diagonal line for each processing area is set to a unit dimension in the biaxial direction. . The laser processing apparatus which processes using the correction method of the laser irradiation position of Claim 1 or 2.