JP2002045985A - Method for machining ellipsoidal hole with laser beam and device for machining ellipsoidal hole with laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for machining an ellipsoidal hole with a laser beam and a device for machining an ellipsoidal hole with a laser beam, by which a highly precise ellipsoidal hole is easily machined. SOLUTION: The laser beam 1a is condensed in an ellipsoidal form on a work 4a, and the machining of the ellipsoidal hole is performed by making the focused image 10 of the laser beam 1a on the work 4a eccentric with respect to the optical axis x of the laser beam 1a and scanning in a circular form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Laser elliptical hole drilling method and laser elliptical hole drilling method for drilling through holes or blind holes in a workpiece such as a thin plate made of non-metallic material by using a laser, particularly for drilling an elliptical hole. It concerns the device.

[0002]

2. Description of the Related Art In recent years, as circuit boards have become smaller and lighter,
There is a need for a through hole or a blind hole on a circuit board to have a diameter of 200 μm or less. When such an extremely small through hole or blind hole is formed on a circuit board, the hole is formed using a laser such as a carbon dioxide gas laser, an excimer laser or a YAG laser. Further, in order to obtain the electrical contact resistance of the circuit board together with the necessity of miniaturization of the circuit board, holes such as through holes having an elliptical shape instead of a circular shape are formed. A conventional method of performing an elliptical hole processing is to focus a laser on the workpiece using a mask having an elliptical hole in an elliptical shape, or on the workpiece,
There is a method in which the laser focus position is scanned on an ellipse.

[0003]

However, in the method of forming an elliptical hole using a mask, when a relatively large hole is to be formed, the processing time is limited by the laser output, or the processing time is long or impossible. There was a problem of becoming. On the other hand, there are the following three methods for processing an elliptical hole by scanning a laser on an ellipse, but each has a problem. First, the method of scanning a laser on an ellipse using a galvanomirror involves changing the position of the galvanomirror due to temperature change or aging, and furthermore, performing high-precision elliptical hole processing due to the limit of its resolution. There was a problem that can not be. In addition, a method of scanning a laser condensing position on an ellipse by converging a laser beam on a workpiece and driving an XY stage for holding the workpiece on an ellipse includes the following steps. There is a problem that it is difficult to drive with accuracy. In addition, a method of scanning the laser on an ellipse by reciprocating a stage holding the workpiece in a predetermined direction while revolving the condensing position of the laser on the workpiece and synchronizing the laser is disclosed in Japanese Patent Application Publication No. A drive mechanism for controlling and reciprocating motion is required, and it is difficult to control with high accuracy.

Accordingly, an object of the present invention is to provide a laser elliptical hole drilling method and a laser elliptical hole drilling apparatus capable of performing highly accurate elliptical hole drilling by an easy method.

[0005]

As a means for solving the above problems, the present invention focuses a laser on an object to be processed in an elliptical shape, and forms an image of the laser on the object,
An elliptical hole is formed by eccentricity with respect to the optical axis of the laser and circular scanning.

According to the present invention, an image of a laser condensed in an elliptical shape on a workpiece is circularly scanned while being decentered with respect to the optical axis of the laser, so that the workpiece is not scanned elliptically. An elliptical hole can be formed on the top.

It is preferable that the energy density of the image forming laser is substantially uniform within its elliptical shape range. Thereby, it is possible to perform high-quality elliptical hole processing having the same cross-sectional shape on the workpiece.

[0008] As means for solving the above-mentioned problems, the present invention provides an elliptical condensing means for converging a laser on a workpiece in an elliptical shape, and forming an image of the laser on the workpiece by: And circular scanning means for eccentrically scanning the optical axis of the laser and performing circular scanning.

In the present invention, the laser is condensed in an elliptical shape on the workpiece by the elliptical focusing means, and the image of the laser on the workpiece is decentered with respect to the optical axis of the laser by the circular scanning means. In addition, by performing circular scanning, an elliptical hole can be formed on a workpiece without performing elliptical scanning.

It is preferable that the amount of eccentricity of the image with respect to the optical axis of the laser is adjustable. This makes it possible to arbitrarily adjust the size of the elliptical shape condensed on the workpiece.

It is preferable that the elliptical condensing means condenses the laser into an elliptical shape through a mask having an elliptical hole.

It is preferable that the elliptical condensing means condenses the laser into an elliptical shape via a cylindrical lens.

It is preferable that the elliptical condensing means adjusts the size of the elliptical shape of the image by adjusting the position of the cylindrical lens in the optical axis direction. Thereby, it is possible to arbitrarily adjust the size of the elliptical shape focused on the workpiece.

It is preferable that the energy density of the laser for the image formation is substantially uniform within its elliptical shape range. Thereby, it is possible to perform high-quality elliptical hole processing having the same cross-sectional shape on the workpiece.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a schematic configuration diagram of a laser elliptical hole machining apparatus according to the present invention. This laser elliptical hole processing apparatus includes a laser oscillator 1, an elliptical condensing means 2, a circular scanning means 3, and a stage 4 for fixing a workpiece 4a on an upper surface.

The elliptical condensing means 2 includes a beam expander 5 for expanding a laser beam diameter of a laser 1a (a circular section having a diameter of 1 mm) oscillated from the laser oscillator 1 to a diameter of 2 mm in the present embodiment. A total reflection mirror 6 for totally reflecting the laser 1a in the horizontal direction emitted from the expander 5 vertically downward, as shown in FIG.
The mask 7 has an elliptical hole having a minor axis of 0.5 mm and a major axis of 1 mm, and converts the laser 1a reflected from the total reflection mirror 6 into a laser 1b having an elliptical cross section.

The circular scanning means 3 comprises an eccentric means 8 and a rotating means 9, and the eccentric means 8 processes the laser 1b passing through the mask 7 with respect to its optical axis x as shown in FIG. On the object 4a, the amount of eccentricity ε (in the present embodiment, ε = 2
0 μm). As shown in FIG. 3, an image 10 of the laser 1b on the workpiece 4a is formed.
Has a cross-sectional area reduced to 1/20 of the imaging magnification of the cross-sectional area of the laser 1 b incident on the eccentric means 8. Rotating means 9
Accommodates the eccentric means 8 inside and the laser 1
This is to rotate about a rotation axis (not shown) which substantially coincides with the optical axis x of b.

Next, a description will be given of the hole machining of the laser elliptical hole machining apparatus having the above configuration.

A circular laser 1a having a cross section of 1 mm in diameter oscillated from the laser oscillator 1 is expanded by a beam expander 5 into a circular laser 1a having a cross section of 2 mm in diameter. After being bent downward, it passes through the mask 7. The laser 1b having a cross section of 0.5 mm in short diameter and 1 mm in long diameter passing through the mask 7 is incident on the eccentric means 8 such that its optical axis x substantially coincides with the rotation axis of the eccentric means 8. As shown in FIG. 3, the laser 1a is eccentric from the optical axis x by an eccentric amount ε = 20 μm on the workpiece 4a by the eccentric means 8 and has a minor axis of 25 μm and a major axis of 50 μm.
To form an image 10 having an elliptical shape.

Next, as shown in FIG. 4, the rotating means 9
When the eccentric means 8 is rotated about the rotation axis, an image 1 is formed.
The center position 10a of the 0 ellipse is moved on a circumference having a radius of ε = 20 μm around the rotation axis. At this time, the image 10 passes and becomes an ellipse having a minor axis of 65 μm and a major axis of 90 μm. At this time, the size of the ellipse may be arbitrarily adjusted by changing the amount of eccentricity ε. Also, by using the mask 7 having different elliptical hole dimensions, the elliptical dimension of the hole to be drilled may be adjusted by arbitrarily adjusting the dimension of the image 10 on the workpiece. good. As described above, an elliptical hole can be formed only by circularly scanning the laser with a simple mechanism without performing the laser elliptical scanning as in the related art.

As shown in FIG. 5, a cylindrical lens 12 is used in place of the mask 7, and a total reflection mirror 6 is used.
The laser 1a having an elliptical cross section may be incident on the eccentric means 8 by passing the laser 1a reflected from the laser beam through the cylindrical lens 12. Furthermore, by adjusting the position of the cylindrical lens 12 in the optical axis x direction, the size of the image 10 on the workpiece may be arbitrarily adjusted to adjust the size of the elliptical shape for boring.

As shown in FIG. 6, when the laser 1a on the image 10 has the highest energy density at the center of the image 10 and the laser 1a has a lower energy density toward the periphery, the laser 1a has The cross section of the hole to be machined on the workpiece 4a has a tapered shape tapering in the penetrating direction.
In some cases, a hole different from the desired elliptical shape is formed on the surface on the penetration side of the laser 1a. Therefore, as shown in FIG. 7, by performing the elliptical hole processing with the laser 1a having a substantially uniform energy density on the image forming 10, the cross section of the hole to be processed on the workpiece 4a is changed to the incident side of the laser 1a. Also, a hole having a desired desired elliptical shape can be formed on the surface on the through side.

[0023]

As is apparent from the above description, according to the present invention, a laser is focused on an object to be processed in an elliptical shape, and the image of the laser on the object is focused on the optical axis of the laser. Since the elliptical hole processing is performed by eccentricity and circular scanning, a high-precision elliptical hole processing can be performed by a simple method of circular scanning without laser elliptical scanning.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a laser elliptical hole processing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the mask of FIG.

FIG. 3 is an enlarged plan view showing an image formed by a laser focused on a workpiece shown in FIG. 1;

FIG. 4 is an enlarged plan view showing a state at the time of machining the elliptical hole of FIG. 3;

FIG. 5 is an overall configuration diagram of a laser elliptical hole machining apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram showing a non-uniform energy density distribution of a laser at a cross section I in FIG. 4 and a cross section I of a workpiece when drilling is performed by the laser.

7 is a diagram showing a substantially uniform energy density distribution of a laser at a cross section I in FIG. 4 and a cross section I of a workpiece when a hole is drilled by the laser.

[Explanation of symbols]

 1a laser 2 elliptical focusing means 3 circular scanning means 4a workpiece 10 imaging x optical axis

Claims (8)

[Claims] An elliptical hole is formed by converging a laser beam on an object to be processed into an elliptical shape and eccentrically forming an image of the laser beam on the object to be processed with respect to the optical axis of the laser beam and performing circular scanning. A laser elliptical hole machining method. 2. The energy density of the image forming laser is:
2. The laser elliptical hole machining method according to claim 1, wherein the laser beam is substantially uniform within the elliptical shape range. 3. An ellipse condensing means for converging a laser on an object to be processed into an ellipse, and an image of the laser on the object is circularly scanned while being decentered with respect to the optical axis of the laser. A laser elliptical hole machining apparatus comprising a circular scanning means. 4. The laser elliptical hole machining apparatus according to claim 3, wherein an eccentric amount of the image with respect to an optical axis of the laser is adjustable. 5. The laser elliptical hole processing apparatus according to claim 3, wherein the elliptical focusing means focuses the laser in an elliptical shape via a mask having an elliptical hole. 6. The laser elliptical hole machining apparatus according to claim 3, wherein the elliptical focusing means focuses the laser in an elliptical shape via a cylindrical lens. 7. The elliptical light condensing means is capable of arbitrarily adjusting the size of the elliptical shape of the image by adjusting the position of the cylindrical lens in the optical axis direction. 7. The laser elliptical hole processing device according to 6. 8. The energy density of the image forming laser is:
The laser elliptical hole machining apparatus according to any one of claims 3 to 7, wherein the laser ellipse holes are substantially uniform within the elliptical shape range.