JPH04237589A - Laser beam machine - Google Patents

Abstract

PURPOSE:To uniformly irradiate a wide soldering area with a laser beam in laser soldering. CONSTITUTION:This laser beam machine is constituted of a YAG laser 1, an optical fiber 2 for transmitting the laser beam emitted from the YAG layer 1, a lens 3 for condensing the laser beam emitted from the optical fiber 2 and galvanomirrors 4, 6 for scanning the laser beam past the lens 3. A work 5 can be irradiated with the laser beam having affinely uniform beam intensity by scanning the laser beam at a high speed with the galvanomirrors and, therefore, the effect of improving the quality of processing is obtd.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a laser processing device.
In particular, the present invention relates to a laser soldering device using a YAG laser.

0002

2. Description of the Related Art A conventional laser processing apparatus, as shown in FIG. 3, includes a laser light source 8, an optical fiber 9 for transmitting the laser beam emitted from the laser light source 8, and a a condensing optical system 10 that condenses light;
The output part of the optical fiber 9 and the condensing optical system 10 are connected to the workpiece 11
The robot 12 is configured to position the robot 12 relative to the robot 12.

[0003] When a laser is used for solder reflow, a YAG laser is usually used as the laser light source 8. The YAG laser beam is transmitted through an optical fiber 9 having a core diameter of several hundred μm, and the laser beam emitted from the optical fiber 9 is focused and irradiated onto the soldering location. When soldering IC leads, etc., the robot 12 scans the condensing optical system and sequentially solders the leads on one side.
Improves work efficiency.

In the laser processing apparatus shown in FIG. 3, the optical magnification of the focusing optical system that focuses the laser beam emitted from the optical fiber 9 is approximately 0.5 to 2 times, and the core diameter of the optical fiber 9 is Considering that the diameter is several hundred μm, the beam waist diameter of the laser beam focused by the focusing optical system is about 1 mm at most. On the other hand, the optimum beam diameter for soldering varies depending on the shape of the parts to be soldered, and is usually about 1 to 3 mm. Therefore, in conventional laser processing equipment, the beam diameter is expanded by defocusing the condensing optical system to obtain the optimum beam diameter for various parts. FIG. 4(a) is a side view showing how the defocus amount h and the beam diameter d change. Figures 4(b) and (c)
) are graphs showing the intensity distribution of the laser beam in cross section A and cross section B shown in FIG. 4(a), respectively. When the beam is just focused, the beam diameter d becomes the minimum and the peak value of the beam intensity becomes the maximum.As the beam is defocused from there, the beam diameter d increases and the peak value of the beam intensity decreases. However, even if the beam diameter is changed by defocusing, the intensity distribution of the laser beam always becomes a Gaussian distribution.

[0005]

[Problems to be Solved by the Invention] In the conventional laser processing apparatus described above, the intensity distribution of the laser beam always becomes a Gaussian distribution because the focusing optical system is defocused to widen the beam diameter. Since the beam intensity differs greatly between the center and the periphery, the laser beam cannot be uniformly irradiated over a wide soldering area, resulting in poor soldering quality.

[0006]

[Means for Solving the Problems] A laser processing apparatus of the present invention includes a laser light source, an optical fiber that transmits the laser beam emitted from the laser light source, and a condensing laser beam that is emitted from the optical fiber. The method includes a condensing optical system and a galvano mirror that scans the laser beam condensed by the condensing optical system at high speed, and irradiates the laser beam scanned by the galvano mirror to a predetermined position of the workpiece. It is characterized by

[0007]

Embodiments Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

The laser processing apparatus shown in FIG. 1 includes a YAG laser 1, an optical fiber 2 for transmitting the laser beam emitted from the YAG laser 1, and a lens 3 for condensing the laser beam emitted from the optical fiber 2. , a galvano mirror 4 that scans the laser beam passing through the lens 3 in one direction;
A galvano mirror 6 scans the laser beam reflected by the galvano mirror 4 in a direction perpendicular to the scanning direction of the galvano mirror 4 and irradiates the workpiece 5 with the laser beam, and positions the workpiece 5 with respect to the laser beam. The XY stage 7 is configured to include an XY stage 7.

A laser beam emitted from a YAG laser 1 is transmitted through an optical fiber 2 and condensed by a lens 3. The laser beam focused by the lens 3 is irradiated onto the workpiece 5, but since two galvano mirrors 4 and 6 are placed in the optical path between the lens 3 and the workpiece 5, the galvano mirror By driving 4 and 6,
The laser beam can be scanned over an area of several square millimeters on the processing surface of the workpiece 5.

Generally, the size of the soldered portion of a printed circuit board is several square millimeters at most, so the galvanometer mirrors 4 and 6 can scan the laser beam over the entire soldered portion. At this time, by making the laser beam scan at a constant speed and making the speed sufficiently faster than the heat transfer rate of the workpiece 5 generated by laser beam irradiation, a laser beam with a pseudo-uniform beam intensity is irradiated. equal to what was done. FIG. 2(a) is a graph showing the beam intensity distribution of the laser beam, which has a Gaussian distribution where the beam intensity is high at the center. Figure 2(b)
is a beam intensity distribution obtained when scanning a laser beam having the beam intensity shown in FIG. 2(a). Uniform beam intensity can be obtained almost over the scanning range. Since the galvanometer mirror has a response frequency of several 100 Hz to several kHz, it is possible to scan the mirror quickly enough so that it can be considered that a laser beam with uniform beam intensity is irradiated over the scanning range of the laser beam.

In this embodiment, the positions of the optical fiber 2, lens 3, and galvano mirrors 4 and 6 are fixed, and the workpiece 5 is positioned with respect to these optical systems by the XY stage 7. 5 may be fixed at a fixed position, and the optical fiber 2, lens 3, and galvano mirrors 4 and 6 may be mounted on a robot and positioned.

[0013]

[Effects of the Invention] The laser processing device of the present invention creates pseudo-uniformity by scanning the laser beam at high speed with a galvano mirror instead of directly irradiating the workpiece with a laser beam having a Gaussian distribution of beam intensity. Since the workpiece can be irradiated with a laser beam with a certain beam intensity, the processing quality is improved and the product yield is improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention.

[Fig. 2] Fig. 2 (a) is a graph showing the beam intensity distribution of the laser beam shown in Fig. 1, and Fig. 2 (b) is a graph when scanning a laser beam having the beam intensity distribution shown in Fig. 2 (a). 3 is a graph showing a beam intensity distribution obtained in FIG.

FIG. 3 is a perspective view showing an example of a conventional laser processing device.

FIG. 4(a) is a side view showing the relationship between defocus amount and beam diameter in the laser processing apparatus shown in FIG. 3;
(b) and (c) are graphs showing beam intensity distributions in cross section A and cross section B shown in FIG. 4(a), respectively.

[Explanation of symbols]

1 YAG laser 2, 9 Optical fiber 3 Lens 4, 6 Galvano mirror 5, 11 Workpiece 7 XY stage 12 Robot

Claims (3)

[Claims] 1. A laser light source, an optical fiber for transmitting a laser beam emitted from the laser light source, a condensing optical system for condensing the laser beam emitted from the optical fiber, and a condensing optical system comprising: 1. A laser processing apparatus comprising: a galvanometer mirror that scans a focused laser beam at high speed; and a laser beam scanned by the galvanometer mirror is irradiated onto a predetermined position of a workpiece. 2. The laser processing apparatus according to claim 1, wherein the laser beam is irradiated onto a predetermined position of the workpiece by a positioning stage on which the workpiece is mounted and positioned. 3. The laser processing apparatus according to claim 1, wherein the laser beam is irradiated onto a predetermined position of the workpiece by a robot that moves the optical fiber emitting section, the condensing optical system, and the galvano mirror together.