JP2001105167A - Method for laser beam scanning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for laser beam scanning capable of carrying out working for a large working region in a short time. SOLUTION: A maximum travelling distance Lmax of the laser beam projecting position is fixed based on driving characteristic of a galvanoscanner. The working region is divided so that at least longitudinal or lateral width W of each region becomes not larger than the maximum travelling distance Lmax. Laser beam is projected zigzag on each of the divided regions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a laser scanning method, and more particularly to a laser scanning method in a laser processing apparatus provided with a galvano scanner.

[0002]

2. Description of the Related Art A laser processing apparatus provided with a galvano scanner is constructed, for example, as shown in FIG. More specifically, the laser processing apparatus shown in FIG.
, A mirror 22, a galvano scanner 23, and an f-θ lens 24.

In this laser processing apparatus, a laser oscillator 21 generates a laser beam having a wavelength suitable for a purpose, such as an ultraviolet laser beam. The laser light emitted from the laser oscillator 21 is reflected by the mirror 22 and enters the galvano scanner 23 at a predetermined incident angle. The galvano scanner 23 includes an X-axis mirror (not shown) for changing the traveling direction of the laser light along the X-axis direction and a Y-axis mirror (not shown) for changing the traveling direction of the laser light along the Y-axis direction. ), And emits the laser light while changing its traveling direction. It is assumed that both the X axis and the Y axis are parallel to the surface of the workpiece 25. f
The -θ lens 24 condenses the laser light emitted from the galvano scanner 23 and irradiates the laser light to the processing target 25. At this time, the f-θ lens 24 condenses the laser light so that the laser light is incident on the processing object 25 perpendicularly (that is, perpendicular to the XY plane). Ablation or melting occurs in the processing target 25 irradiated with the laser light, and processing such as drilling and welding can be performed.

As described above, in this type of laser processing apparatus, an arbitrary point on the processing target 25 can be irradiated with laser light using the galvano scanner 23. In addition, the galvano scanner 23 has a high operation speed, and can change the emission direction of the laser light at an extremely high speed. Therefore, a general-purpose printed circuit board (PCB: Printed Circuit)
It is often used to form a large number of holes, such as for drilling holes on a board.

When drilling holes in a general-purpose printed circuit board, the laser beam irradiation position is continuously changed in order to efficiently irradiate a large number of processing points arranged in a matrix (or lattice points) with a laser pulse. There must be. Conventionally, when such drilling is performed, the irradiation position of the laser beam is changed as follows.

[0006] First, the processing points arranged in a matrix are X-axis and Y-axis.
So that each column formed by the processing points is parallel to the X axis (or Y axis), and each row formed by the processing points is parallel to the Y axis (or X axis). The printed circuit board is held by the laser processing device. Then, as shown in FIG. 3A or 3B, the irradiation position of the laser beam is changed so as to follow the processing point.

More specifically, in the example of FIG. 3A, the irradiation position of the laser beam is changed so that the processing point (indicated by a circle) of the first line is traced from the top to the bottom of the figure, and then the second line is changed. The irradiation position of the laser beam is changed so that the processing point is traced upward from the bottom of the figure. Thereafter, the irradiation position of the laser beam is changed so that the odd-numbered rows follow the processing point from top to bottom and the even-numbered rows follow from bottom to top. In the example of FIG. 3B, the irradiation position of the laser beam is changed so that the processing point in the first row traces from right to left in the figure, and then the processing point in the second row moves from left to right in the figure. The irradiation position of the laser beam is changed so as to follow. Thereafter, the odd-numbered columns are
From right to left, the even-numbered columns change the irradiation position of the laser beam so as to follow the processing point from left to right. in this way,
In the conventional laser scanning method, laser light is scanned in a zigzag manner. (Here, changing the irradiation position of the laser beam by rotating and driving the mirror of the galvano scanner 23 is referred to as “scanning or scanning”, and the laser beam irradiation is not necessarily performed. Note that when scanning each column (or row), only the X-axis mirror (or Y-axis mirror) of the galvanometer scanner 23 is driven, and when moving from each column to the next column, the galvanometer is used. Only the Y-axis mirror (or X-axis mirror) of the scanner 23 needs to be driven. The actual irradiation of the laser beam is performed by irradiating each processing point with a pulsed laser beam.

As described above, in the conventional laser scanning method, a laser beam is scanned so as to sequentially trace a plurality of processing points arranged in a matrix one by one.

[0009]

SUMMARY OF THE INVENTION A galvano scan is
As shown in FIG. 4, there is a relationship between the mirror rotation angle and (operation time between processing points) + (settling time). That is, the galvano scan is capable of high-speed operation if the rotation angle of each mirror is small, but (rotation time between processing points) + (settling time) becomes exponentially longer as the rotation angle increases. It has driving characteristics.

Therefore, in a conventional laser scanning method in which processing points arranged in rows and columns are traced line by line, as the size of the printed circuit board increases (the vertical or horizontal width of the array of processing points increases). There is a problem that more time is required in proportion to the increase in the area.

An object of the present invention is to provide a laser scanning method which enables processing in a short time even in a large processing area.

[0012]

According to the present invention, there is provided a laser scanning method for dividing a processing target area into a plurality of areas and irradiating a laser beam with a galvano scanner for each of the divided areas. A laser scanning method is provided in which the size of the region is determined based on the driving characteristics of the galvano scanner.

Here, when a plurality of processing points are arranged in a matrix in the processing area, the irradiation of the laser beam is performed in a zigzag manner for each of the divided areas.

According to the present invention, there is provided a laser scanning method for irradiating a plurality of processing points arranged in a matrix on a surface of an object to be processed with a laser beam using a laser processing apparatus having a galvano scanner. Based on the driving characteristics of the scanner, determine the maximum value of the linear movement distance of the laser light on the surface of the processing object, when the length of the row and column constituted by the plurality of processing points are both larger than the maximum value By dividing the surface of the processing object into a plurality of regions, the length of a row or a column formed by the processing points in each region is made smaller than the maximum value, and for each region, A laser scanning method characterized in that the laser light irradiation is performed.

More specifically, the irradiation of the processing point with the laser beam is performed in a zigzag manner.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The laser scanning method of the present invention is performed using a laser processing device having a galvano scanner.

First, taking into account the number, arrangement, and spacing of the processing points of a printed circuit board as a processing object, the linear movement of laser light on the surface of the processing object based on the driving characteristics of the galvano scanner of the laser processing apparatus. The maximum value of the distance (or the maximum rotation angle of the X-axis mirror or the Y-axis mirror of the galvano scanner) Lmax is determined. This maximum value Lmax is
Determined so that the ratio between the rotation angle of the mirror and the time required for rotating the mirror by the rotation angle and stopping the mirror is maximized (so that {(operating time + settling time) / rotation angle} is minimized). Just do it. The maximum value Lmax of the linear movement distance should be considerably smaller than the width of the scannable area of the galvano scanner. Then, the processing area of the printed circuit board is divided into a plurality of areas such that the width (vertical or horizontal length) W of each area is equal to or less than its maximum value Lmax. This division is performed even when the scannable area is smaller than the scannable area of the galvano scanner. FIGS. 1A, 1B, and 1C show examples of processing region division.

Next, the printed circuit board is introduced into the laser processing apparatus, and is held so that the arrangement of the processing points is parallel to the X axis and the Y axis. By holding the printed circuit board in this way, it becomes possible to rotate each of the X-axis mirror or the Y-axis mirror of the galvano scanner independently and scan each column or each row of the processing point.

Thereafter, each region is scanned with a laser beam in a zigzag manner as in the conventional case. That is, processing is performed by irradiating each processing point with a laser light pulse while changing the laser light irradiation position so as to trace each processing point in a zigzag manner. This situation is indicated by arrows in each example of FIGS. 1 (a), (b) and (c). In the present embodiment, the maximum value Lmax of the moving distance of the laser beam is determined for the sake of convenience for dividing the processing region, and in actual laser scanning,
Linear scanning beyond that is possible. Therefore, as shown in FIG. 1, scanning can be continuously performed from each divided area to the next divided area.

In the case of this embodiment, one mirror (for example, an X-axis mirror) of the galvano scanner is reciprocally rotated and the other mirror is intermittently operated, thereby scanning the laser beam in a zigzag manner. be able to. When drilling a general-purpose printed circuit board, the frequency of the reciprocating rotation is about 500 Hz at the maximum in the conventional laser scanning method. On the other hand, in the laser scanning method of the present invention, driving at 800 Hz or more is possible. As a result, even when laser beam scanning is performed on a wide processing area, laser beam scanning can be performed with a time increase that is proportional to an increase in area.

[0021]

According to the present invention, the processing time can be shortened by dividing the processing region and performing laser beam scanning for each region.

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are diagrams each showing an example of division of a processing region; FIGS.

FIG. 2 is a diagram illustrating an example of a configuration of a laser processing apparatus including a galvano scanner to which the present invention is applied.

FIGS. 3A and 3B are diagrams showing a movement locus of a laser beam irradiation position by a conventional laser scanning method.

FIG. 4 is a graph showing a relationship between a rotation angle of a mirror of a galvano scanner and a driving time.

[Explanation of symbols]

 21 Laser Oscillator 22 Mirror 23 Galvano Scanner 24 f-θ Lens 25 Workpiece

Claims (4)

[Claims] 1. A laser scanning method for dividing a processing region into a plurality of regions and irradiating a laser beam using a galvano scanner for each of the divided regions, wherein the size of the divided region is determined by the galvano scanner. A laser scanning method characterized in that the laser scanning method is determined based on driving characteristics. 2. The method according to claim 1, wherein a plurality of processing points are arranged in a matrix in the processing area, and the irradiation of the laser light is performed in a zigzag manner for each of the divided areas. Laser scanning method. 3. A laser scanning method for irradiating a laser beam to a plurality of processing points arranged in a matrix on a surface of an object to be processed using a laser processing apparatus having a galvano scanner, Determining the maximum value of the linear movement distance of the laser light on the surface of the processing object, and when the lengths of rows and columns formed by the plurality of processing points are both larger than the maximum values, the processing object By dividing the surface into a plurality of regions, the length of a row or column formed by the processing point in each region is made smaller than the maximum value, and for each region, the irradiation of the laser light to the processing point is performed. A laser scanning method characterized by being performed. 4. The laser scanning method according to claim 3, wherein the laser beam is irradiated to the processing point in a zigzag manner.