JPH0220681A - Focusing method for laser beam - Google Patents

Abstract

PURPOSE:To focus a laser beam to a regular energy density distribution by allowing the laser beam which is adjusted through a beam diameter adjusting lens group to pass through a cylindrical lens provided so as to be turnable centering around an optical axis. CONSTITUTION:A laser beam 3 which is outputted from a laser oscillator 1 is allowed to pass through a beam diameter adjusting lens group 2 for moving along its optical axis 4 and its diameter is adjusted. Subsequently, the laser beam 3 whose diameter is adjusted is allowed to pass through a cylindrical lens 6 provided so as to be turnable centering around said optical axis 4. As a result, the laser beam 3 is focused to an elliptic shape 7 of a prescribed size. As for this focusing beam of an elliptic shape, its energy density does not go to an irregular multi-mode distribution, and such working as cutting, etc. by a laser beam can be executed exactly. Also, by turning said cylindrical lens 6, working in a desired direction can be executed easily.

Description

[Detailed Description of the Invention] [Summary] Regarding a laser beam focusing method for focusing a laser beam into an ellipse of a predetermined size, the present invention relates to a laser beam focusing method that does not cause irregular distribution of energy density when focusing the laser beam. 1. A cylindrical lens into which the laser beam adjusted by the beam diameter adjustment lens group is incident is provided rotatably around the optical axis, and the laser beam is directed to a predetermined position through the cylindrical lens. The light is focused into an oval shape, and the direction of the oval shape can be changed in a predetermined direction by rotating the cylindrical lens as necessary.

[Industrial application field]

The present invention relates to a laser beam focusing method for focusing a laser beam into an oval shape of a predetermined size.

When cutting the pattern wiring of a printed circuit board that is widely used in electronic devices due to modification or the like, it is recently done by irradiating the circuit board with a laser beam.

Irradiation of such a laser beam is performed at a predetermined location of the pattern wiring to be cut by focusing it into a slit shape with a length longer than the width of the pattern wiring and having a predetermined width. A disconnection is made.

Therefore, it is important that such a laser beam is focused so as to obtain an energy density that can easily cut the patterned wiring stretched over the printed circuit board.

[Conventional technology]

Conventionally, the configuration was as shown in the conventional configuration diagram shown in FIG. FIG. 3(a) is an explanatory view, and FIG. 3(b) is a perspective view.

As shown in FIG. 3(a), the laser oscillator 1 generates a laser beam 3 having an optical axis 4 from the laser crystal unit IB by irradiating the laser crystal unit B with light emitted from the excitation lamp IC. The laser beam generated by the laser crystal unit I-B is amplified by a total reflection mirror IA and a half-reflection mirror IE arranged before and after the laser crystal unit I-IB, and the laser beam is emitted from the half-reflection mirror IE side. It is formed so that the output of beam 3 is carried out.

Further, such a laser beam 3 is directed to a predetermined location of the patterned wiring 11 with a beam radius having a predetermined circular cross-sectional shape by an aperture ID having a circular through hole IF provided therein. When converging and cutting the pattern wiring 11, the aperture ID described above is replaced with the aperture 12 provided with the slits 2A having the width TI and the length B1, and the laser beam 38 formed in the shape of the slit 12A is used. The width T2 can be adjusted by changing the distance between the convex lens and the concave lens of the beam diameter adjustment lens group 2.
An adjustment was made to make the length B2.

Therefore, the laser beam 3A having the width TI and the length B1 is adjusted by the beam diameter adjusting lens group 2 to have the width T2 and the length B2.
The beams were focused in the shape of a rectangle 13.

In this case, if the laser beam 3A is irradiated to a location other than the pattern wiring 11 to be cut, the surface of the printed circuit board 10 that does not need to be cut will be burned out. is focused to be slightly larger than the width of the pattern wiring 11, and the pattern wiring 11 of the width is focused by irradiation with the laser beam 3A.
The amputation was carried out.

Also, depending on the direction in which the pattern wiring 11 is stretched, the rectangle 13
In this case, the direction of the rectangle 13 can be changed by rotating the aperture 12 in the direction of arrow A depending on the stretching direction of the pattern wiring 11. is taken into consideration.

Therefore, sliding in the direction of arrow C to change the mutual distance between the convex lens and the concave lens of the beam diameter adjustment lens group 2;
By rotating the aperture 12 in the direction of arrow A, the laser beam 3A is adjusted so that a rectangle 13 of a predetermined size is formed at the part of the pattern wiring 11 to be cut. An amputation was taking place.

[Problem to be solved by the invention]

Normally, the laser beam 3 output from such a laser oscillator 1 has an energy distribution of the diameter of the laser beam 3 at a predetermined position S, as shown in (a) of the conventional laser beam energy distribution graph in FIG. The density P is output so as to have a Gaussian distribution with a peak at the center and a low density at both ends.

By forming the rectangle 13 in this manner, energy attenuation occurs due to interference, etc., and the energy density P of the laser beam 3A becomes a multimode distribution, resulting in an irregular distribution.

Therefore, if, for example, the energy density of Po is required to cut the pattern wiring 11 as described above, there will be a portion where the energy density of Po cannot be obtained with the laser beam 3A formed in the rectangular shape 13, and the pattern wiring 11 will be cut. However, there was a problem in that the connection wiring 11 could not be completely cut.

Therefore, an object of the present invention is to prevent irregular distribution of energy density from occurring when focusing a laser beam.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

As shown in FIG. 1, a cylindrical lens into which the laser beam adjusted by the beam diameter adjustment lens group is incident is provided rotatably around the optical axis, and the laser beam is adjusted to a predetermined size through the cylindrical lens. The light is focused into an oval shape with a diameter of about 100 mm, and the direction of the oval shape can be changed in a predetermined direction by rotating the cylindrical lens as necessary.

With this configuration, the above-mentioned problem is solved.

[Effect]

That is, by providing a cylindrical lens on which the laser beam transmitted through the beam diameter adjustment lens group is irradiated, the laser beam is focused into an oval shape in a predetermined direction by the cylindrical lens, and the focused oval shape is The direction of the cylindrical lens can be changed by rotating the cylindrical lens.

Therefore, when focusing is performed using such a cylindrical lens, the energy density distribution of the laser beam is
Unlike the case of forming a rectangular aperture with a conventional slit aperture, an irregular multi-mode distribution is not obtained (a relatively uniform distribution is obtained, and the pattern wiring is not cut due to the lack of energy as described above). You can prevent it from disappearing.

〔Example〕

The present invention will be explained in detail below with reference to FIG.

FIG. 2 is an explanatory diagram of an embodiment according to the present invention, in which (a) is a perspective view and (b) is an energy distribution graph of a laser beam. The same reference numerals indicate the same objects throughout the figures.

As shown in FIG. 2(a), a laser beam 3 having a diameter output from a laser oscillator 1 is moved by a beam diameter adjusting lens group 2 by a moving mechanism 8, and a cylindrical lens is rotated by a rotating mechanism 9. It is focused into an oval 7 by the lens 6, and the printed circuit board 1 is focused by the focused oval 7.
The structure is such that 0 pattern wiring 11 is irradiated.

Further, the moving mechanism 8 is driven by the gear 8B by the drive of the motor 8A.
The moving body 8C is rotated through the moving body 8C, and the guide rod 8D moves along the helical groove 8E provided on the outer periphery of the moving body 8C, thereby aligning the beam diameter adjustment lens group 2 housed in the moving body 8C with the optical axis. 4 in the direction of arrow C to move the distance between the cylindrical lens 6 and the pattern wiring 11, and the rotation mechanism 9 rotates the rotating body 9C via the gear 9B by driving the motor 9A. The cylindrical lens 6 housed in the rotating body 9C is rotated in the direction of arrow A around the optical axis 4.

Furthermore, a thrust bearing 14 is provided between the moving mechanism 8 and the rotation mechanism 9, and is formed so that they can rotate freely with respect to each other.

In this case, the ellipse 7 to be irradiated is the beam diameter adjusting lens group 2.
Since the predetermined beam diameter adjusted by is further focused by the cylindrical lens 6, the lengthwise size of the oval 7 is adjusted by the beam diameter adjusting lens group 2, and the widthwise size is By sliding in the direction of arrow C, the focal point of the cylindrical lens 6 can be brought closer to the focal point of the cylindrical lens 6, and by moving it further away, it can be widened and focused to a predetermined width.

Therefore, the stretched pattern wiring 1 of the printed circuit board 10
The rotating mechanism 9 rotates the cylindrical lens 6 so that the oval 7 is perpendicular to the cylindrical lens 1, and the moving mechanism 8 slides the beam diameter adjustment lens group 2 so that an oval 7 with a predetermined width B is formed. The laser beam 3 can be adjusted accordingly.

Therefore, by irradiating the pattern wiring 11 with the laser beam 3 adjusted to have an oval shape 7, the cutting shown at the cutting location 11A can be performed.

In this case, a width peak is created by the cylindrical lens 6, and a Gaussian distribution, which is an ideal energy density distribution, is obtained.

Therefore, the laser beam 3 focused on the oval 7 of width B by the configuration of the cylindrical lens 6 has the energy density P0 necessary to cut the pattern wiring 11 at all locations, and the laser beam 3 is focused on the oval 7 of width B. The pattern wiring 11 can be completely cut by irradiation with the focused laser beam 3.

〔Effect of the invention〕

\ As explained above, according to the present invention, a laser beam can be focused into an ellipse using a cylindrical lens, and the direction of the ellipse can be freely changed, and the focused laser beam has energy. The density distribution can be made uniform.

Therefore, by using an aperture with a slit like the conventional one, it is possible to prevent the energy density distribution from becoming irregular, and when cutting the pattern wiring, it is possible to avoid incomplete cutting, and to ensure that the pattern wiring is cut. This can be done in many ways and has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 is an explanatory diagram of an embodiment according to the present invention, in which (a) is a perspective view and (b) is an energy distribution graph of a laser beam. FIG. 3 is a conventional configuration diagram. FIG. 4 shows an energy distribution graph of a conventional laser beam. In the figure, 1 is a laser oscillator. 2 is a beam diameter adjustment lens group. 3.3A is a laser beam. 4 is the optical axis. 6 is a cylindrical lens. 7 indicates an oval shape. Tree f: Akira Yo Kazumi) 5 cases of nephew! 2nd m and dark 1) Ruzozu C Saka Ao Makuto/1. /)Purchase drawing No. 3m Kimata Moe wo niyoroichisho Kata Hibenkyo no Meizu ('f 2)-5
Place L (a) 15th place I 0 o'clock

Claims (1)

[Claims] A laser oscillator (1) that outputs a laser beam (3);
a beam diameter adjustment lens group (2) that moves along the optical axis (4) of the laser beam (3) and adjusts the diameter of the laser beam;
), the laser beam focusing method comprises: a cylindrical lens ( 6) is provided to be rotatable around the optical axis (4), and the laser beam (
3) into an oval (7) of a predetermined size,
A method for focusing a laser beam, characterized in that the direction of the oval (7) can be changed in a predetermined direction by rotating the cylindrical lens (6) as necessary.