JPS6230879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a galvanometer optical scanning laser processing apparatus.

Moving a laser beam in two dimensions is an essential technology for applications such as laser processing, and
There are two methods: one uses a reflecting mirror fixed on a table, and the other uses the rotation of a reflecting mirror mounted on the rotating shaft of the galvanometer. The former allows a minute spot to be obtained with high positional accuracy over a wide movement range, and the latter allows extremely high speed movement. . High speed is required for laser trimming of thick film hybrid ICs and resistance modules, which are in high demand among laser processing equipment. That is, high speed is required for the movement of the laser beam during positioning from resistor to resistor to be trimmed, and for the movement when cutting the resistor while irradiating the laser beam. In this case, an excellent method is to scan the light with a galvanometer, with an acceleration of 10G at rise and a moving speed of several m/m.
seconds are easily obtained and widely used.

By the way, recently, in applications such as laser trimming and laser marking for printing lot numbers etc. on specimens, the processing width is usually around 50 μm, but there are many cases where a wider processing width is required. For example, in the case of laser trimming, hybrid ICs used in high-voltage circuits require high voltage resistance, so the trimming width needs to be wide. In addition, in laser marking, a wider processing width is required to make printed characters easier to see.

In order to widen the processing width, it is easy to think of increasing the spot diameter of the laser beam focused by a condensing lens, but by increasing the spot diameter, the power density decreases and the processing becomes difficult. This resulted in disadvantages such as reduced capacity, insufficient resistance, and unclear text.

An object of the present invention is to provide a galvanometer optical scanning type laser processing apparatus which can obtain a wide processing width while eliminating these conventional drawbacks and maintaining processing characteristics.

According to the present invention, a galvanometer optical scanning laser performs processing by rotating a reflecting mirror attached to the rotating shaft of a moving coil galvanometer based on a position signal and moving the reflected light of a laser beam incident on the reflecting mirror. 1. In a processing device, laser beams are scanned in mutually orthogonal directions according to position signals.
A minute sinusoidal perturbation signal is superimposed on the position signal that drives the pair of galvanometers and one of the galvanometers,
A galvanometer light comprising a circuit that superimposes a minute cosine perturbation signal on a position signal that drives the other side of the galvanometer, and is characterized in that scanning of the laser beam is accompanied by a minute circular or elliptical movement to improve processing characteristics. A scanning laser processing device is obtained.

Next, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows an example of the configuration of a galvanometer optical scanning type laser processing apparatus which is an embodiment of the present invention.

The laser beam emitted from the laser oscillator 11 is transmitted to the beam expander 12 and the X-axis galvanometer 1.
3. The beam is moved at high speed by the Y-axis galvanometer 14, and is irradiated onto the sample 17 through the objective lens 15 and the 90° reflecting mirror 16. The X-axis position signal 18 that controls the rotation angle of the X-axis galvanometer is
The signal is applied to the X-axis galvanometer 13 via the X-axis galvanometer driver 19 to control the X coordinate on the sample surface, and similarly the Y-axis position signal 20 is applied to the Y-axis galvanometer 14 via the Y-axis galvanometer driver 21. , controls the Y coordinate on the sample surface. A small sinusoidal perturbation sinwt signal 22 is superimposed on the input of the X-axis galvanometer driver 19 in addition to the X-axis position signal 18, while a small cosine perturbation in addition to the Y-axis position signal 20 is superimposed on the input of the Y-axis galvanometer driver 21. A coswt signal 23 is superimposed. As a result of such perturbations being superimposed on the X and Y axes, optical scanning in the X and Y planes on the sample surface involves circular motion, depending on the magnitude of the superimposed sine and cosine perturbations. This will involve elliptical motion. Here, when the X-axis position signal is x and the amplitude of the sinusoidal perturbation is α ₁ , the X-axis position signal X when perturbed is expressed as X=x+α ₁ sinwt (1).

Similarly, the Y-axis position signal Y when perturbed is Y
When the axis position signal is y and the amplitude of the cosine perturbation is α ₂ , it is similarly expressed as Y=y+α ₂ coswt (2).

Eliminating wt from (1) and (2), (X-x) ² /α ₁ ² + (Y-y) ² /α ₂ ² =
1......(3) is derived.

This is centered at (x, y) and has a radius α in the X direction
₁ represents an ellipse with radius α ₂ in the Y direction, indicating that it is accompanied by elliptical motion. When α ₁ = α ₂ , the motion is circular. That is, the laser beam is scanned in the direction designated by the position signal while making a small circular motion. FIG. 2 schematically shows this situation. FIG. 2a shows a conventional machining trajectory without perturbation, and FIG. 2b shows a machining trajectory according to the present invention. By doing this, a wide processing width can be obtained. Also, since it is a circular motion and has a component that reciprocates in the direction of movement, the same point will be irradiated with the laser beam several times. Therefore, the processing ability of the laser beam is increased compared to the conventional method, and better processing characteristics can be obtained with the same laser power. By appropriately selecting the amplitudes of the perturbations applied to the X and Y axes, the width of the machining trajectory can be controlled, and the conditions for repeated irradiation can also be controlled, so that the machining characteristics can also be controlled.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of a galvanometer optical scanning laser processing apparatus, which is an embodiment of the present invention.
Figures a and b are schematic diagrams showing a conventional machining trajectory and a machining trajectory of the present invention. 11... Laser oscillator, 12... Beam expander, 13, 14... X-axis Y-axis galvanometer, 15... Objective lens, 16... 90° reflecting mirror,
17... Sample, 18, 20... Position signal, 19,
21... Galvanometer driver, 22, 23...
...is the applied perturbation signal.

Claims (1)

[Claims] 1. In a galvanometer optical scanning laser processing device that performs processing by rotating a reflecting mirror attached to the rotating shaft of a moving coil galvanometer based on a position signal and moving the reflected light of the laser beam incident on the reflecting mirror, a pair of galvanometers that scan laser beams in mutually orthogonal directions according to the position signal; and a position signal that drives the other galvanometer by superimposing a minute sinusoidal perturbation signal on the position signal that drives one of the galvanometers. What is claimed is: 1. A galvanometer optical scanning laser processing device comprising: a circuit for superimposing a minute cosine perturbation signal on a laser beam;