JP3368425B2 - Laser scanning method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser scanning method, and more particularly to a laser scanning method in a laser processing apparatus equipped with a galvano scanner.

[0002]

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

In this laser processing apparatus, the laser oscillator 21 generates laser light having a wavelength according to the purpose, such as ultraviolet laser light. 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) that changes the traveling direction of laser light along the X-axis direction and a Y-axis mirror (not shown) that changes the traveling direction of laser light along the Y-axis direction. ) And, the laser light is emitted while changing its traveling direction. The X axis and the Y axis are both parallel to the surface of the processing target 25. f
The -θ lens 24 condenses the laser light emitted from the galvano scanner 23 and irradiates the object to be processed 25. At this time, the f-θ lens 24 condenses the laser light so that the laser light enters the object 25 to be processed perpendicularly (that is, perpendicular to the XY plane). Ablation, melting, or the like occurs in the processing object 25 irradiated with the laser light, and processing such as drilling or welding can be performed.

As described above, in this type of laser processing apparatus, the galvano scanner 23 can be used to irradiate a laser beam on an arbitrary point on the object 25 to be processed. Moreover, the galvano scanner 23 has a high operating speed, and can change the emitting 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 when making holes in a board.

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

First, the machining points arranged in a matrix are X-axis and Y-axis.
So as to be located along the axis, that is, 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 light 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 as to trace the processing point (indicated by ◯) on the first line from the top to the bottom of the diagram, and then the second line. The irradiation position of the laser light is changed so that the processing point of is traced from the bottom to the top of the figure. Thereafter, the irradiation position of the laser light is changed so that the odd-numbered rows trace the processing points from the top to the bottom and the even-numbered rows trace the processing points from the bottom to the top. Further, in the example of FIG. 3B, the irradiation position of the laser beam is changed so that the machining point in the first row is traced from the right to the left in the figure, and then the machining point in the second row is changed from the left to the right in the figure. The irradiation position of the laser light is changed so as to follow. After that, the odd numbered columns are
In the even-numbered columns from right to left, the irradiation position of the laser light is changed so as to trace the processing point from left to right. in this way,
In the conventional laser scanning method, laser light is scanned in a zigzag shape. (Here, rotating the mirror of the galvano scanner 23 to change the irradiation position of the laser light is referred to as "scanning or scanning", and the irradiation of the laser light is not always performed. Note that when scanning each column (or row), only the X-axis mirror (or Y-axis mirror) of the galvano scanner 23 is driven, and when moving from one column to the next, the galvano Only the Y-axis mirror (or X-axis mirror) of the scanner 23 needs to be driven. The actual irradiation of laser light is performed by irradiating each processing point with pulsed laser light.

As described above, in the conventional laser scanning method, the laser light is scanned so that the plurality of processing points arranged in a matrix are sequentially traced line by line.

[0009]

The 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 galvanoscan can operate at high speed if the rotation angle of each mirror is small, but as the rotation angle increases, (operation time between processing points) + (settling time) becomes exponentially long. It has driving characteristics.

Therefore, in the conventional laser scanning method in which processing points arranged in rows and columns are traced line by row, as the printed circuit board becomes larger (the width of the array of processing points becomes wider). 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 capable of processing a large processing area in a short time.

[0012]

According to the present invention, a region to be processed is divided into a plurality of regions, and a laser scanning method of irradiating a laser beam using a galvano scanner for each of the divided regions is performed. A laser scanning method can be obtained 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 laser beam irradiation is performed in a zigzag shape for each of the divided areas.

Further, according to the present invention, in the laser scanning method of irradiating a laser beam to a plurality of processing points arranged in a matrix on the surface of an object to be processed using a laser processing apparatus equipped with a galvano scanner, the galvano When the maximum value of the linear movement distance of the laser light on the surface of the object to be processed is determined based on the driving characteristics of the scanner, and the lengths of rows and columns formed by the plurality of processing points are both larger than the maximum value. In, by dividing the surface of the object to be processed into a plurality of areas, the length of the row or column formed by the processing points in each area is made smaller than the maximum value, and for each area, to the processing points A laser scanning method is obtained which is characterized in that the laser light irradiation is performed.

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

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The laser scanning method of the present invention is carried out using a laser processing device having a galvano scanner.

First, in consideration of the number, arrangement, and spacing of the processing points of the printed circuit board which is the processing object, the linear movement of the laser light on the surface of the processing object is performed 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 Y-axis mirror of the galvano scanner) Lmax is determined. This maximum value Lmax is
Determined to maximize the ratio of the rotation angle of the mirror and the time required to rotate the mirror by that rotation angle and make it stand still (to minimize {(operating time + settling time) / rotation angle}). 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 the maximum value Lmax. This division is performed even when the scannable area is narrower than the scannable area of the galvano scanner. An example of processing area division is shown in FIGS. 1 (a), 1 (b) and 1 (c).

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

After that, each region is scanned with laser light in a zigzag shape as in the conventional case. That is, the laser light irradiation position is changed so that each processing point is traced in a zigzag manner, and each processing point is irradiated with a laser light pulse for processing. The state is shown by an arrow in each of the examples of FIGS. 1A, 1B, and 1C. It should be noted that the maximum value Lmax of the moving distance of the laser light in this embodiment is determined for the sake of dividing the processing area for convenience, and in the 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 the present embodiment, one mirror (for example, an X-axis mirror) of the galvano scanner is reciprocally rotated, and the other mirror is intermittently operated to scan the laser beam in a zigzag manner. be able to. By the way, in the case of drilling a general-purpose printed circuit board, the frequency of this reciprocating rotary motion was about 500 Hz at maximum in the conventional laser scanning method. On the other hand, the laser scanning method of the present invention can drive at 800 Hz or higher. As a result, even when laser light scanning is performed on a wide processing area, laser light scanning can be performed with a time increase that is proportional to the increase in area.

[0021]

According to the present invention, the processing area is divided and the laser beam scanning is performed for each area, so that the processing time can be shortened.

[Brief description of drawings]

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

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

FIG. 3A and FIG. 3B are diagrams showing a movement locus of an irradiation position of laser light 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 driving time.

[Explanation of symbols]

21 Laser oscillator 22 mirror 23 Galvo Scanner 24 f-θ lens 25 Object to be processed

Claims (4)

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