JPH09308983A - Laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve the machining speed for a work by splitting the laser beam from an laser beam oscillator into a plurality of laser beams, and controlling each driving mechanism performing the same action corresponding to the split number. SOLUTION: The pulse laser beam generated by a laser beam oscillator 10 is split into two in sectional area with a 45 deg. reflecting mirror 11, and guided to masks 13a, 13b by changing the angle by 90 deg.. The split laser beam by each mask is reduced in the beam diameter, and guided to X-Y scanners 14a, 14b. The laser beam scanned by the X-Y scanners is passed through machining lenses 15a, 15b so that works 17a, 17b placed on X-Y tables 16a, 16b are irradiated with the laser beam. The X-Y tables are provided with a drive mechanism in the X-axis direction and a drive mechanism in the Y-axis direction, and move the works on the X-Y plane to adjust the position. A driving mechanism is built in the X-Y scanners and X-Y tables respectively, which are controlled by a control device 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus suitable for forming minute via holes in a printed wiring board.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and more sophisticated, the density of mounted components mounted on a printed circuit board and the lead pitch have been reduced. In order to cope with such progress, it is required that the diameter of a via hole formed in a printed wiring board be 0.3 (mm) or less.

Conventionally, drilling of a printed wiring board is performed by machining with an NC drill or exposure (photo via method). However, in the NC drill, the diameter of the hole is limited to 0.2 (mm), and the drill is often broken. On the other hand, in the photo via method, 0.15 (m
m) is the limit, and the material cost is high.

[0004] As a means for solving the above-mentioned problems, a laser processing apparatus for performing drilling with a laser beam has recently been provided. In this laser processing apparatus, a pulsed laser beam is generated by a laser oscillator, and the number of pulses and the energy for one hole are adjusted to perform drilling to a desired depth. On the other hand, with respect to the diameter of the hole, a mask for defining the diameter is arranged in the light guide path of the laser light, and the laser light is narrowed down by this mask, so that the hole provided in the workpiece can be reduced.

[0005] In addition, since the laser processing does not damage the metal, there is an advantage that the conductor pattern can be processed without damage even in processing after laminating the insulating layer film or processing from the base film side.

[0006]

An excimer laser is used as a laser oscillator. However, due to the etching speed (depth per pulse), the processing speed is relatively slow and the operating cost is high. There is a problem. On the other hand, a TEA (Transversely) having a narrow pulse width, high peak power and high energy density can be obtained.
Excited Atmospheric Press
ure) CO ₂ lasers are receiving attention. This TEA
Since a laser processing apparatus using a CO ₂ laser has an etch speed one digit or more higher than that of an excimer laser, the number of laser irradiation pulses required for processing per hole can be reduced, and the processing speed can be increased.

However, the above TEA CO
The processing speed even when using the ₂ laser is limited,
There is a need for an improvement to reduce the processing cost per hole.

An object of the present invention is to provide a laser processing apparatus capable of greatly improving a processing speed.

Another object of the present invention is to reduce the size of the laser processing apparatus.

[0010]

According to the present invention, there is provided a laser processing apparatus for irradiating a laser beam from a laser oscillator onto a work arranged on an XY table to perform processing. A plurality of dividing means is provided, the plurality of sets of the XY table and its drive mechanism are provided according to the number of divisions, and a control device for controlling each drive mechanism is provided, and the control device includes each drive mechanism. Are controlled so as to perform the same operation.

Proximity sensors that operate when the mutual approach distance becomes a predetermined value or less are provided at opposite ends of the XY tables that are adjacent to each other. It has an interlock function of stopping the operation of the corresponding XY table when receiving the detection signal.

Further, the predetermined value is set to be larger than the distance required to stop by the interlock function when the XY table is operating at the maximum speed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In FIG.
The pulsed laser light generated by the laser oscillator 10 by the TEA CO ₂ laser is divided into two by the 45 ° reflection mirror 11 with respect to its cross-sectional area, and guided to the masks 13a and 13b by changing the 90 ° angle. Mask 13
At a and 13b, the beam diameter of the split laser light is narrowed down by passing through the hole that defines the diameter of the via hole, and is guided to the XY scanners 14a and 14b. X-
The Y scanners 14a and 14b are for oscillating the laser light, and the oscillated laser light acts as a focusing lens and is also called a processing lens 15a also called an fθ lens.
Workpieces (for example, printed wiring boards) 17a, 17 placed on the XY tables 16a, 16b through 15b
b. The XY tables 16a and 16b have a drive mechanism in the X-axis direction and a drive mechanism in the Y-axis direction, and can move the works 17a and 17b on the XY plane to adjust the positions.

The XY scanners 14a and 14b and the XY tables 16a and 16b each have a built-in drive mechanism, and these drive mechanisms are controlled by the controller 1.

In FIG. 2A, a 45 ° reflecting mirror 1
1 has two reflecting surfaces 11a and 11b that intersect at 90 °, so that the incident laser light is 2
Can be equally divided. For example, as shown in FIG. 2B, when the cross section of the laser beam is a square of 12 × 12 (mm), it can be equally divided into two laser beams having a cross section of 6 × 12 (mm). it can. In the masks 13a and 13b, the divided laser light is narrowed down through a hole (usually a diameter of 1 to 2 mm) having a diameter determined according to the reduction ratio M and the diameter of the via hole. Since it is sufficiently smaller than the area, there is no inconvenience caused by splitting the laser beam.

By the same principle, if a three-sided pyramidal reflecting mirror having three reflecting surfaces and a four-sided pyramidal reflecting mirror having four reflecting surfaces are used, the laser light can be divided into three equal parts and four equal parts. .

FIG. 3 shows another example of the laser beam splitting means, which is an example of splitting the laser beam into two by using a 50% reflection mirror 21. The 50% reflective mirror 21 is formed by applying a reflective material to one half to form a reflective mirror 21a and the other half to be a transparent portion 21b of a total transmission type, so that the laser light can be bisected in terms of the sectional area.

By using the reflection mirror as described above,
The laser light can be split without lowering the energy density of the laser light.

In FIG. 4, the XY scanner 14a (1
4b) is a so-called galvano-mirror system formed by combining two galvano-mirrors 14-1 and 14-2. That is, by independently rotating the two reflecting mirrors based on the driving principle of the galvanometer, it is possible to continuously irradiate the laser beam to a plurality of desired positions on the work 17 through the processing lens 15.

A preferred example of the mask will be described with reference to FIG. The mask 13 includes a disk-shaped mask plate 13-1 having holes (here, 16 holes) H1 to H16 having different diameters at equal angular intervals in the circumferential direction, and a mask plate 13-1.
-1 and slightly larger than each of the holes H1 to H of the mask plate 13-1.
16 has windows W1 to W8 in an area corresponding to
Mask holder 13-2 for holding 3-1 and FIG.
As shown in FIG. 7, the driving unit 13-3 includes a motor that rotationally drives the mask plate 13-1 and the mask holder 13-2 combined together.

The mask 13 is arranged so that the holes H1 to H16 pass through the optical path of the laser beam when the mask plate 13-1 is rotated. In other words, the rotation axis of the mask plate 13-1 is parallel to the optical path of the laser light, and the holes H1 to H
The virtual circles connecting the centers of the sixteen are arranged in the optical path of the laser light. Although not shown, the mask 13 further finely adjusts the position of the combination of the mask plate 13-1 and the mask holder 13-2 or the entire mechanism in parallel with respect to the surface of the mask plate 13-1. A mask position biaxial fine adjustment mechanism is provided for finely adjusting the center position of the hole corresponding to the optical path of the laser light.

The material of the mask plate 13-1 is SUS.
Since it is necessary to irregularly reflect the reflected light of the laser beam so as not to affect other optical components of the laser light guide system, the surface is subjected to processing such as shot blasting. The diameter of the hole of the mask plate 13-1 is excellent in processability with respect to a resin such as epoxy or PI used for a high-density multilayer printed wiring board, and the energy density (fluence) of the processed surface is about 10 J / cm ² . It is designed based on the principle of the mask projection method. In this example, reduction ratio (M value)
Is designed to be about 10. In this case, the mask plate 13-
When one hole H10 is selected, the diameter of the via hole becomes 0.1
(Mm). This reduction rate (M value) is
It can be set arbitrarily by changing the distance between -1 and the processed lens.

The diameter of the via hole currently used is 0.1.
(Mm) is the mainstream, so the diameters of the holes H1 to H16 provided in the mask plate 13-1 are mainly 1 to 2 (mm) and values before and after them, that is, H1: 8, H2: 6, H
3: 4, H4: 3, H5: 2, H6: 1.8, H7:
1.6, H8: 1.4, H9: 1.2, H10: 1.
0, H11: 0.9, H12: 0.8, H13: 0.
7, H14: 0.6, H15: 0.5, H16: 0.4
(The unit is mm). These holes are arranged counterclockwise in order from the larger one.

The drive unit 13-3 drives the mask plate 13-1 to rotate under the control of the controller 1. That is, in the control device 1, the drill data set by the operator, C
A hole corresponding to the diameter of the via hole designated based on the master data such as an AD file is selected, and the mask plate 13-1 is rotated so that the hole is located in the optical path of the laser beam. Generally, a hole diameter is specified by a T code in drill data. In this example, the desired hole diameter can be set by rotating the mask plate 13-1 based on this T code.

Returning to FIG. 1, the XY scanners 14a and 1
4b is preferably arranged in a line-symmetric relationship with respect to the 45 ° reflecting mirror 11. This is because the laser beam has a property that the beam diameter increases as the beam divergence angle, that is, the optical path length increases. On the other hand, the above arrangement makes it easier to make the distance from the laser light emission port of the laser oscillator 10 to the processing surface of the workpieces 17a and 17b equal, and makes the energy density of the laser light on the processing surface the same. be able to.

Next, the positioning of the works 17a and 17b will be described. A plurality of pins for positioning the works 17a, 17b are provided on the XY tables 16a, 16b, and a plurality of holes into which the pins can be inserted are provided in the works 17a, 17b, respectively. Further, although not shown in FIG. 1, ITV cameras are installed diagonally above the XY tables 16a and 16b, respectively. This is because the workpieces 17a and 17b are provided with alignment marks for positioning, and the alignment marks are read by image processing before the laser processing, and the workpieces 17a and 17b are read.
This is for accurate positioning of a and 17b. Therefore, the image signal from the ITV camera is sent to the control device 1, and in the control device 1, the image processing unit processes the image signal so that the alignment marks of the works 17a and 17b come to a predetermined position. , 16b are controlled.

The control of the XY tables 16a and 16b at the time of laser processing by the controller 1 will be described with reference to FIG. In principle, each of the XY tables 16a and 16b can be independently operated by a built-in drive mechanism. However, in this example, the control device 1 controls the respective drive mechanisms so that the XY tables 16a and 16b perform exactly the same operation. That, X-Y table 16a is time to move a distance X ₁ to the left in the figure, in synchronization with this movement also X-Y table 16b to the left in the figure by a distance X _1. Further, when the XY table 16a moves upward in the figure by the distance Y ₁ , the XY table 16b also moves upward in the figure by the distance Y ₁ in synchronization with this.

Therefore, the XY tables 16a, 16
If b is accurately driven and controlled, the XY table 1
6a and 16b do not collide. However, it is possible that the XY tables 16a and 16b move in different directions due to a malfunction. When the movement directions are such that the movement directions approach each other, the XY tables 16a and 16b may collide. In order to prevent such a collision, the layout may be such that the movable ranges of the XY tables 16a and 16b do not overlap with each other, as indicated by the alternate long and short dash line in FIG. But,
In the layout as shown in FIG. 6A, the XY table 16
The installation space for a and 16b becomes large, and the processing apparatus becomes large.

On the other hand, in this example, the XY table 1
A plurality of proximity sensors 1 that operate when the approach distances of the opposing ends of 6a and 16b are equal to or less than a predetermined value.
Proximity sensors 16-1a, 16-2a, 16 are provided with 6-1a, 16-2a, 16-1b, 16-2b.
The detection signals -1b and 16-2b are input to the control device 1. When the control device 1 receives a detection signal indicating that the approach distance has become equal to or less than a predetermined value from any of the proximity sensors, the X-X control unit activates the interlock function.
An interlock signal for instructing the driving mechanism of the Y tables 16a and 16b to stop is output.

Here, the predetermined value is the XY table 1
It goes without saying that the distance is set to be larger than the moving distance required to completely stop the interlock function when the interlock function is activated in the state where 6a and 16b are operating at the maximum speed.

By doing the above, as shown in FIG. 6 (b), the movement range of the XY table 16a is made into a one-dot chain line, and the movement range of the XY table 16b is made into a two-dot chain line. It can be partially overlapped.
As a result, only the areas where the respective moving ranges overlap are shown in FIG.
The installation space can be made smaller than in the case of (a).

For reference, FIGS. 6A and 6B are shown in FIG.
An example of the actual size of the device corresponding to is shown. FIG. 6 (a)
In the device corresponding to (1), the width dimension is 2050 (mm), whereas in the device corresponding to FIG. 6B according to the present invention, the width dimension is 1550 (mm), and the size can be significantly reduced.

Although the above description is for the case of two XY tables, it is clear that the same applies to the case of three or more tables.

In any case, in this embodiment, the laser light from the laser oscillator 10 is divided into two without being reduced in its energy density and guided to two laser processing systems to form two workpieces 17a and 17b. By performing exactly the same drilling processing, the processing speed can be doubled. Therefore, the processing cost per hole can be significantly reduced.

Although the present invention is most effective when used for a TEA CO ₂ laser, the existing CO ₂ laser,
The present invention is applicable to any processing apparatus such as a YAG laser and an excimer laser, and the form of the laser light may be either pulsed or continuous wave. The workpiece is particularly suitable for a printed wiring board or a flexible printed wiring board, but can also be applied to other resins and glass.

[0036]

According to the present invention, the laser beam from one laser oscillator can be divided into a plurality of laser beams without reducing the energy density and introduced into a plurality of processing systems that perform exactly the same processing. The processing speed of can be greatly improved, and as a result, the processing cost can be significantly reduced. In addition, the space occupied by the plurality of XY tables can be reduced to reduce the size of the device.

[Brief description of drawings]

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

FIG. 2 is an enlarged view (FIG. 2A) for explaining the operation of the 45 ° reflecting mirror shown in FIG. 1 and a view (FIG. 2B) for explaining a cross-sectional shape of laser light.

FIG. 3 is a diagram for explaining an alternative example of the 45 ° reflecting mirror shown in FIG. 1;

4 is a diagram showing a schematic configuration of the XY scanner shown in FIG.

5 is a diagram showing the configuration of another example of the mask shown in FIG.

6 is a diagram for explaining the movement of the XY table shown in FIG. 1. FIG.

FIG. 7 is a side view showing an example of a processing apparatus size according to a general control method and the present invention method.

[Explanation of symbols]

 11 45 ° reflection mirror 11a, 11b reflection surface 15, 15a, 15b processing lens 16a, 16b XY table 17, 17a, 17b work 21 50% reflection mirror

Claims (3)

[Claims] 1. A laser processing apparatus for irradiating a laser beam from a laser oscillator onto a work arranged on an XY table for processing, comprising a dividing means for dividing the laser beam from the laser oscillator into a plurality of pieces. , A plurality of sets of the XY table and its drive mechanism according to the number of divisions, and a control device for controlling each drive mechanism, and the control device controls each drive mechanism to perform the same operation. A laser processing apparatus characterized in that. 2. Proximity sensors that operate when approaching distances are equal to or less than a predetermined value are provided at opposing ends of the XY tables that are adjacent to each other, and the control device controls the proximity sensors from the proximity sensors. 2. The laser processing apparatus according to claim 1, further comprising an interlock function for stopping the operation of the corresponding XY table when receiving the detection signal. 3. The predetermined value is set to be larger than a distance required to stop by the interlock function when the XY table is operating at the maximum speed. Item 2. A laser processing device according to item 2.