JP2002316288A - Correction method of laser irradiation position in laser processing - Google Patents

Abstract

(57) [Summary] (With correction) [PROBLEMS] To easily and quickly create information for correcting a deviation between a position to be irradiated with a laser beam and a position to be actually processed. SOLUTION: The displacement of a small number of test holes in a workpiece 5 is measured, and the characteristic distortion caused by the galvanometer 3 and the fθ lens 4 that can represent the displacement of the entire processing region by nonlinear regression analysis is expressed. Performing high-precision processing by calculating the coefficients of each term in the calculation formula by multiple regression analysis and correcting the irradiation position of the laser beam using the above calculation formula when actually processing the workpiece Becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for correcting a laser beam irradiation position in laser processing.
Irradiating a laser on a synthetic resin substrate etc. to process holes,
In the method of marking characters on a glass substrate, a laser that obtains information for correcting a laser irradiation position so that a laser beam can be irradiated to an accurate position, and uses such correction information to correct the laser beam irradiation position The present invention relates to a method for correcting a laser beam irradiation position in processing.

[0002]

2. Description of the Related Art Laser processing technology is used to process through holes or via-ball holes in a high-density wiring circuit board or to mark characters on a liquid crystal substrate.

[0003] Laser processing technology is a method of irradiating a workpiece with a laser beam and melting or evaporating the workpiece with the energy of the laser beam to make holes or mark characters. Widely used in the manufacture of

[0004] A specific example of the prior art of laser processing is disclosed in Japanese Patent Application Laid-Open No. 8-174256.

In the prior art described in the above-mentioned prior art document, as shown in FIG. 1, a galvanometer 3 and an fθ lens 4 are arranged in an optical path of a laser beam emitted from a laser transmitter 2, and a mirror 3a of the galvanometer 3 is provided. Is mechanically driven so that a desired position on the workpiece 5 is irradiated with the laser beam.

[0006] In such laser processing, there is a problem that a deviation occurs between a position to be irradiated with a laser beam and a position to be actually irradiated, thereby deteriorating the accuracy of laser processing. For example, in the prior art, a pincushion distortion caused by a geometrical arrangement of a mirror of a galvanometer and a geometrical distortion caused by a linearity error in an optical design of an fθ lens may occur. know.

Therefore, the above-mentioned prior art document discloses a technique for correcting a deviation of a laser beam irradiation position. A substrate for a test is prepared, and a laser beam is irradiated to coordinate points arranged in a grid at equal intervals in a square area designed on the substrate to perform drilling. If there is no shift in the laser beam irradiation position, the processed hole should exist exactly at the lattice point of the square. However, since the laser irradiation position is 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,
The deviation of the laser beam irradiation position at each grid point is determined. The deviation of the irradiation position of the laser beam at the intermediate position between the lattice points can be obtained by interpolation calculation of the deviation at the adjacent lattice points.

[0008] Such a shift of the laser beam irradiation position is input as correction information to a control unit for controlling a galvanometer or the like provided in the laser irradiation device, and when the workpiece is actually processed, the laser beam irradiation is performed. If the irradiation position is corrected on the control data, it is possible to accurately irradiate the target position with the laser and perform high-precision processing.

[0009]

In the above-described method for acquiring correction information in the prior art, in order to ensure processing accuracy, the positions of a large number of processing holes are measured when generating correction information. For example, in the example shown in FIG. 2, since the position of as many as 4225 holes is measured, the measurement is difficult without a dedicated measuring device.

Further, it is necessary to create this correction information every time the optical system is adjusted or a change with time occurs, and the troublesome work and time required for this have been a serious problem.

Therefore, an object of the present invention is to make it possible to easily create the correction information in a short time.

[0012]

A method of correcting a laser irradiation position in laser processing according to the present invention measures the amount of displacement of a small number of test holes in a test workpiece, and performs non-linear regression analysis on the entire area of the processing area. A calculation formula capable of expressing the displacement is obtained, and the predicted displacement amount of the actual machining point is calculated and corrected based on the formula at the time of actual machining. This calculation formula is a non-linear polynomial expressing characteristic distortion caused by the galvanometer and the fθ lens, and calculates the coefficient of each term by multiple regression analysis. According to the present invention, a calculation formula corresponding to correction information can be easily created in a short time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a laser processing apparatus according to the present embodiment, in which a character is marked on a liquid crystal substrate by irradiating a laser beam with a laser beam. Because there are many components,
This will be described with reference to FIG. A substrate 5 serving as a workpiece is mounted on an XY table 1, and a pulsed laser beam emitted from a laser oscillator 2 is applied to the surface of the substrate 5 via a pair of XY galvanometers 3 and an fθ lens 4. The galvanometer 3 reflects the laser beam on the mirrors 3a and 3b which can freely rotate, and changes the irradiation direction of the laser beam.
The laser beam deflected by the galvanometer 3 is further deflected in a direction perpendicular to the surface of the substrate 5 by passing through the fθ lens 4 and then irradiates the surface of the substrate 5. XY
By combining the galvanometers 3 in both directions, fθ
An arbitrary position in the field of view of the lens 4 can be irradiated with the laser beam.

FIG. 2 shows the results of drilling holes in a test work material in a matrix at equal intervals in the above-described laser processing apparatus. At the actually processed position, a barrel-shaped distortion occurs as shown in FIG. Regarding the processing position in the Y direction,
In addition to the offset and scaling of the entire machining position, especially the curve connecting the same X target position has the shape of a quadratic curve, and the slope becomes steeper as the absolute value in the Y direction increases. Assuming that the target value is (x, y) and the Y position after processing is g (x, y), it is predicted that g (x, y) = a + b ^* x + c ^* y + d ^* y ^* x ^* x.

Regarding the processing position in the X direction, although the concavity and convexity of the quadratic curve are different, a similar tendency is observed. Therefore, the target value is (x, y), and the X position after processing is f (x, y). Then, it is predicted that f (x, y) = e + f ^* x + g ^* y + h ^* x ^* y ^* y is approximated.

The results obtained by drilling 25 test holes, which are significantly less than in the case of FIG.
Shown in

[0018]

[Table 1]

As is clear from Table 1, a maximum of about 2 mm of distortion occurs in a 70 mm square processing area. For this data, the target position is (x, y), the measurement position is (f (x, y), g (x,
y)), the coefficients a to d and e to h of each term in f (x, y) and g (x, y) are calculated by non-linear multiple regression analysis: a = 9.00013 b = −0.000177143 c = 1.000123 d = 0.000000000000544940 e = -2.80009 f = 1.100128 g = 0.117142 h = 0.0000000000000273553.

Based on this result, the difference between the processing target position and the measurement position is determined as a pre-correction shift, and the processing target position (x, y) is substituted into the above f (x, y) and g (x, y). The difference between the predicted machining position and the measured position obtained as a result is a shift after correction (Table 1).
The data shown in (Table 2) are obtained by calculating the respective data. It can be seen that a deviation of about 2 mm at the maximum can be corrected to about 0.05 mm.

[0021]

[Table 2]

That is, the laser irradiation target position (x, y)
Is substituted into the above equation and f (x, y) and g (x, y) are calculated, the laser irradiation position at the time of actual processing can be determined with an accuracy of 0.05 mm or less. (X, y)-
If x, g (x, y) -y) is subtracted from the irradiation target position and the laser beam is irradiated, the irradiation target position and the laser beam irradiation position at the time of actual processing become coincident.

In this embodiment, a specific example of the laser processing apparatus has been described as an apparatus for marking a character on a liquid crystal substrate by irradiating a laser, but the laser processing apparatus of this embodiment is a marking apparatus. However, the present invention is not limited to this, and similar effects can be obtained with a laser processing apparatus using a galvanometer and an fθ lens.

[0024]

As described above, according to the present invention, it is not necessary to measure the amount of displacement of multiple test holes in order to obtain a calculation formula corresponding to correction information. Since the measurement of the amount of displacement is sufficient, the number of work steps can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic structure of a laser processing apparatus.

FIG. 2 is a plan view showing a state of distortion when holes are formed in a matrix at equal intervals.

[Explanation of symbols]

 5 Work material

Claims (1)

[Claims] 1. A method for correcting a deviation between a position to be irradiated with a laser beam and a position to be actually processed in laser processing for irradiating a workpiece with a laser beam. Measure the positional deviation of a small number of test holes in the workpiece, find a calculation formula that can express the deviation of the entire processing area by nonlinear regression analysis, and calculate the predicted deviation of the actual processing point from the calculation formula during actual machining A method of correcting a laser beam irradiation position in laser processing to calculate and correct.