JP2005034878A - Laser beam machining method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method and a laser beam machining apparatus which attain a rapid laser beam machining without impairing the shape of an object to be machined and attain improvement and stabilization of machining quality. <P>SOLUTION: When the object 8 is machined by emitting laser beams, a single-mode is selected in a machining initial stage and a multi-mode is selected in a machining period. A beam mode changing means changes a beam mode by changing a distance between a condensing lens and a mask during machining or changing an aperture diameter during machining. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser processing method and apparatus for performing processing by irradiating a processing target with a laser beam, and more particularly to a laser processing method and apparatus capable of improving and stabilizing processing quality.

  A laser drill apparatus that irradiates a printed wiring board with a laser beam to open a hole has been put into practical use. Regarding a laser beam used for drilling a printed wiring board, Patent Document 1 discloses that a Gaussian wave having a larger energy at the center portion than that at the periphery portion, as schematically shown in FIG. It is described that a beam having a distribution is converted into a beam having a top hat distribution with a uniform intensity as schematically shown in FIG.

Japanese Patent Laid-Open No. 2002-120080

  Conventionally, however, the beam mode is constant even if the pulse width, energy, etc. of the laser beam are variable. Therefore, when a single mode laser oscillator having a Gaussian distribution as shown in FIG. When the number of pulses necessary for machining is irradiated in the same mode, only the center part of the workpiece 8 is machined or damaged as shown in FIG. Has a problem of occurrence. Conversely, when a multi-mode laser oscillator having a top-hat distribution as shown in FIG. 1B is used, the intensity of the central portion is lower than that of the single mode, so the number of shots required for processing is small. When the resin layer 8C in the copper foil 8B-resin 8C-copper foil 8D layer is processed as shown in FIG. 3, the taper is likely to spread, and the cross-sectional shape of the hole is likely to deteriorate. Had problems.

  The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to enable rapid laser processing without impairing the shape of a processing target, and to improve and stabilize the processing quality.

  The present invention solves the above-mentioned problem by changing the beam mode during the processing when irradiating a processing target with a laser beam.

  The beam mode is a single mode at the beginning of machining and a multi-mode at the end of machining.

  The present invention also solves the above-mentioned problems by providing means for changing a beam mode during processing in a laser processing apparatus for processing by irradiating a processing target with a laser beam.

  Further, the beam mode changing means changes the distance between the condenser lens and the mask during the processing.

  Alternatively, the beam mode changing means changes the aperture diameter during processing.

  According to the present invention, it is possible to eliminate the problems caused by machining in only one of the single mode and the multimode, and to quickly process a good shape, thereby improving and stabilizing the machining quality. Can be achieved.

  For example, if the first few pulses are processed in a single mode and the last few pulses are processed in a multimode, the occurrence of damage in the center due to heat accumulation in the center when only the single mode is used can be suppressed, and It is possible to suppress corner machining residue due to lack of energy. Furthermore, unlike the case where only the multi mode is used, the number of shots required for processing does not increase and the cross-sectional shape of the hole does not deteriorate.

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

  In the present embodiment, as shown in FIG. 4, the laser oscillator 10, the condensing lens 14 and the mask 16 for adjusting the cross-sectional shape of the laser beam 12 output from the laser oscillator 10, and the direction of the laser beam 12 are changed. Bending mirror 18 and scanning mirrors 20 and 22 for changing or scanning as necessary, and scanning by the scanning mirrors 20 and 22 in the X and Y directions along the surface 8A (referred to as a workpiece irradiation surface) of the workpiece 8 In the laser drill apparatus provided with the aperture 24 for regulating the processed beam 30 and the fθ lens 26, the beam mode is changed during the processing by changing the distance L between the condenser lens 14 and the mask 16 during the processing. It is intended to change.

  That is, for example, in the first few pulses, as shown in FIG. 5A, the distance L between the condenser lens 14 and the mask 16 is made relatively large, and the beam diameter a is made smaller than the aperture diameter b of the mask 16. Thus, the single mode is set on the workpiece irradiation surface 8A.

  On the other hand, in the last few pulses, for example, as shown in FIG. 5B, the distance L between the condenser lens 14 and the mask 16 is made small, and the beam diameter a is made larger than the mask opening diameter b, thereby irradiating the workpiece. The multimode is set on the surface 8A.

  In this way, by switching the beam mode during processing, it becomes possible to quickly form a well-shaped hole as shown in FIG.

  In the present embodiment, since the distance L between the condenser lens 14 and the mask 16 is changed during processing, the mode can be changed relatively easily.

  For example, as described in Patent Document 1, the diameter of the aperture 24 is changed during processing by switching the rotating plate in which a plurality of apertures having different diameters are formed around the rotating disk. The mode may be switched.

  In the present embodiment, since the first few pulses are single mode and the last few pulses are multimode, a hole with a bottom as shown in FIG. 6 can be opened quickly and with good quality. Note that the method of changing the beam mode is not limited to the embodiment. For example, by changing the distance L between the condenser lens 14 and the mask 16 continuously, the beam mode can be changed continuously from the single mode to the multimode, or The beam mode can be changed stepwise by the method as described in Patent Document 1. Also, the method of changing the beam mode is not limited to the single mode to the multi mode, and conversely, the multi mode can be changed to the single mode, or the multi mode can be sandwiched between the single modes. .

  In the above-described embodiment, the present invention is applied to laser drilling. However, the application target of the present invention is not limited to this, and it is obvious that the present invention can be similarly applied to laser processing in general other than drilling. .

  The present invention can be applied to laser processing such as laser drilling.

Diagram showing the difference in intensity distribution depending on the laser beam mode Cross-sectional view showing problems when all pulses are processed in single mode Sectional view showing problems when all pulses are processed in multi-mode Optical path diagram showing the overall configuration of an embodiment of the present invention In the said embodiment, the optical path figure which shows the example of the relationship of the mode in the distance between a condensing lens and a mask, and a workpiece | work irradiation surface Sectional drawing which shows the mode of the process in embodiment of this invention

Explanation of symbols

8 Workpiece 8A Workpiece irradiation surface 10 Laser oscillator 12 Laser beam 14 Condensing lens 16 Mask 24 Aperture 26 fθ lens 30 Processing beam L Distance between condensing lens and mask

Claims (5)

When irradiating a processing target with a laser beam,
A laser processing method characterized by changing a beam mode during processing.   2. The laser processing method according to claim 1, wherein the beam mode is a single mode at an initial stage of processing and a multi-mode at the end of the processing. In a laser processing apparatus for processing by irradiating a processing target with a laser beam,
A laser processing apparatus comprising means for changing a beam mode during processing.   4. The laser processing apparatus according to claim 3, wherein the beam mode changing means changes the distance between the condensing lens and the mask during processing.   4. The laser processing apparatus according to claim 3, wherein the beam mode changing means changes an aperture diameter during processing.

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