JPS63302503A - Method and device for laser-trimming - Google Patents

Abstract

PURPOSE:To enable the deflection and variation of the output of laser lights at high speed by a method wherein an acousto-optic optical deflection element is arranged into the optical path of laser lights, the frequency of a drive signal transmitted over the deflection element is changed and a trimming line is controlled while the power of the drive signal is altered and laser power applied onto a work is controlled. CONSTITUTION:When laser lights are condensed onto a work 7 and the work is trimmed, acousto-optic optical deflection elements (AOD) 3, 4 are disposed into the optical path of laser lights. The frequency of a drive signal transmitted over the AODs 3, 4 is altered, the angle of diffraction is changed, a trimming line is controlled while the power, of the drive signal sent to the AODs 3, 4 is varied, and laser power applied onto the work 7 is controlled. An element utilizing the single crystal anisotropic Bragg diffraction phenomenon of tellurium dioxide, etc., is employed as said AODs 3, 4, and two elements are mounted for deflecting laser in the X axis and Y axis directions. Accordingly, response at high speed in approximately 10mus is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser trimming device that trims a workpiece (eg, a hybrid IC, etc.) using laser light.

[Prior art]

In a device that performs trimming using a laser beam, a method using a galvanometer type beam positioner is known as a method for deflecting the laser beam. A specific known example of this is JP-A-58-123702. This is shown in FIG.

In FIG. 4, a laser beam emitted from a laser oscillator 10 passes through a beam expander 11 that expands the beam.
Galvanometer type beam positioner 12 that deflects light
Sent to A and 12B. The laser beam emitted from the beam positioner is transmitted through the scan lens 13. The light is applied to the printed resistor 17A on the hybrid IC 16 through the mirror 14.

By sending required signals to the beam positioners 12A and 12B, the optical path is manipulated to cut and trim the resistor 17A.

[Problem that the invention seeks to solve]

As mentioned above, the conventional technology has the following drawbacks. The first is a galvanometer type beam positioner 1.
2A and 12B are based on the principle that a current is passed through the coil and the electromagnetic force is used to rotate the coil, so the response to the control signal is poor. As shown in Figure 5,
Step control signal (rotation command) to beam positioner
When Ss is given, the positioner's position undergoes a damped oscillation as shown by curve S. Therefore, a predetermined location cannot be irradiated with laser unless a control method is adopted in which laser irradiation is performed after a delay of T after a rotation command is given to the positioner. Due to this delay time T20~Looms, high-speed trimming operation is not possible with the conventional device.

A second drawback is that when changing the cutting line width of the resistor or the diameter of the machined hole, the conventional device requires changing the output of the laser oscillator itself.

In other words, YAG, which is often used in trimming devices.
In conventional lasers, the laser output is changed by changing the excitation lamp current value within the laser oscillator. However, since it takes time for the output to stabilize when the lamp current is changed, it is impossible to vary the laser output at high speed in this respect as well.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser trimming method and a laser trimming device that eliminate the above-mentioned drawbacks of the prior art and make it possible to deflect and change the output of laser light at high speed.

[Means for solving problems]

A laser trimming method according to the present invention created to achieve the above-mentioned object is a method of trimming by focusing a laser beam on a workpiece, in which an acousto-optic light deflection element is arranged in the optical path of the laser beam. Then, the frequency of the drive signal given to the acousto-optic light deflection element is changed to change the diffraction angle to control the trimming line, and the power of the drive signal given to the acousto-optic light deflection element is changed to control the trimming line. This controls the irradiated laser power.

Further, the created laser trimming device of the present invention for carrying out the above method includes: (a) at least two acousto-optic light deflection elements on the optical path of the laser beam, and each of the above-mentioned acousto-optic light deflection elements. (b) the at least two acousto-optic light deflection elements are arranged so that their deflection directions are orthogonal to each other;

and (c) the driver has a structure capable of adjusting the frequency and power of the driver 11+ signal.

[Effect]

The response of the acousto-optic deflection element is significantly faster than that of a galvanometer type positioner or the like. The reason for this is that unlike in the prior art, a member with mass is not moved, but the change in refractive index of the medium caused by the propagation of an ultrasonic signal within the medium is used to act as a diffraction grating. This is because the response is literally on the order of the speed of sound.

Therefore, high-speed laser trimming operation is possible.

〔Example〕

FIG. 1 is a perspective view schematically depicting an example of the apparatus of the present invention configured to carry out the method of the present invention.

In FIG. 1, 1 is a laser oscillator, and 2 is a mirror for changing the laser optical path.

3 and 4 are acousto-optic optical deflection elements (hereinafter abbreviated as AOD) for deflecting laser light in the X-axis and Y-axis.

). For example, some AODs utilize the anisotropic black diffraction phenomenon of a single crystal such as tellurium dioxide. 5 is a mirror, and 6 is a scan lens. The diffracted light emitted from the AOD 4 is focused and irradiated onto a workpiece (printed resistor) 7 via a mirror 5 and a scan lens 6. 8A and 8B are A
This is a driver for driving OD3°4.

In a device with such a configuration, when a drive signal with a predetermined frequency f is applied to the AOD from the driver, the first-order diffracted light of the AOD is deflected as shown in FIG. It becomes f.

By changing the frequency of this drive signal, a predetermined position on the printed resistor 7, which is the workpiece, can be irradiated with laser light.

Next, in order to change the laser power irradiated onto the workpiece, it is sufficient to change the driving power given to the AOD from the driver. This principle will be explained using FIG. 3.

FIG. 3 is a chart showing the driving power and diffraction efficiency (first-order diffracted light power/input power) of the AOD.

Drive power P1~Pa (PI > P2 > Ps)
The diffraction efficiency changes, and using this principle, the laser power irradiated onto the workpiece can be increased or decreased.

AOD utilizes the fact that when an ultrasound signal travels through an acousto-optic medium, the refractive index of the medium changes periodically and acts as a diffraction grating for light, so the ultrasound propagates through the medium. The response time is determined by the time required for the response to occur, and the above-mentioned element using tellurium dioxide is capable of a high-speed response of about 10 μs. Therefore, by implementing the present invention using this type of AOD, it is now possible to perform high-speed deflection and power changes with a response as high as 1/1000, whereas conventional devices were able to deflect with a response of about LOMS. , ultra-high-speed trimming is now possible.

〔Effect of the invention〕

As described in detail above, according to the laser trimming method of the present invention, the laser beam can be deflected at high speed, the output can be changed at high speed, and the laser trimming operation can be performed at high speed. Further, according to the laser trimming device of the present invention, the above method can be easily implemented and its effects can be fully exhibited.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically depicting one embodiment of a laser trimming device according to the present invention, and FIGS. 2 and 3 are charts for explaining the operation of the above embodiment. FIG. 4 is a schematic perspective view showing a conventional laser trimming device, and FIG. 5 is a chart for explaining the problems of the conventional example. 1... Laser oscillator, 2... Mirror, 3.4...
Acousto-optic light deflection element, 5...mirror, 6...scan lens. 7...Printed resistor as workpiece.

Claims (1)

[Claims] 1. A method for trimming by condensing a laser beam onto a workpiece, in which an acousto-optic polarizing element is disposed in the optical path of the laser beam, and a drive signal is applied to the acousto-optic polarizing element. The trimming line is controlled by changing the frequency of the beam to change the diffraction angle, and the power of the drive signal applied to the acousto-optic optical deflection element is changed to control the laser power irradiated onto the workpiece. Laser trimming method. 2. In an apparatus that performs trimming by focusing a laser beam onto a workpiece, (a) at least two acousto-optic light deflection elements are provided on the optical path of the laser light, and a drive power is applied to each of the acousto-optic light deflection elements. (b) the at least two acousto-optic light deflection elements are arranged such that their deflection directions are orthogonal to each other; and (c) the driver adjusts the frequency and power of the drive signal. 1. A laser trimming device characterized by having a structure that obtains the desired results.