JP2007237242A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus which can manufacture holes having various diameters from a small diameter to a large diameter, and further can improve both of machining throughput and machining quality. <P>SOLUTION: The laser beam machining apparatus is separately provided with a scanner for carrying out a positioning operation to a specified machining position on a printed board, and a scanner for carrying out a trepanning operation to form the outside profile of a via-hole. In both of a punching operation and a trepanning operation, the machining throughput and the hole shape can be improved, and various holes from the small diameter to the large diameter can be machined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing method and a laser processing apparatus for processing or cutting holes using laser light, and more particularly to a laser processing apparatus suitable for processing a via hole in a printed wiring board.

  Hereinafter, a conventional laser processing apparatus will be described.

  Along with the downsizing and high-density mounting of electronic devices, printed wiring boards are mainly multilayer wiring boards in which a plurality of boards are stacked. In a multilayer wiring board, it is necessary to electrically connect conductive layers between substrates stacked one above the other. Therefore, a via hole (hole) reaching the lower conductive layer is formed in the insulating layer of the multilayer wiring board, and conductive plating is applied to the inside of the via hole to electrically connect the conductive layers between the substrates stacked vertically. is doing.

For the formation of the via hole, a high-power CO ₂ laser or a UV laser using a harmonic of YAG is used with the miniaturization of the via hole. Further, high-speed processing is realized by scanning a laser beam using a beam scanning optical system in which a galvano mirror and an fθ lens are combined. Furthermore, an aperture is used as a mask to select the hole diameter to be processed, an imaging optical system is used to transfer the image onto the substrate using an imaging lens, and a plurality of laser beams are emitted to one via hole. By irradiating in divided times, the shape quality of the via hole is improved.

  However, the demand for improving throughput for drilling in printed circuit board manufacturing has become increasingly severe as the number of holes has increased due to higher density. In addition, as the hole diameter is reduced, the requirements for positional accuracy are becoming stricter as well.

  In order to meet the demands for improving the processing throughput as described above, a plurality of laser processing apparatuses having multiple processing beams have been proposed. As a method of multi-sizing, a laser processing apparatus (for example, Patent Document 1) that switches laser light temporally and a laser processing apparatus (for example, Patent Document 2) that splits laser light spatially are typical. is there.

Japanese Unexamined Patent Publication No. 2000-263271 (page 8, FIG. 1) Japanese Patent Laying-Open No. 2004-230466 (page 11, FIG. 5)

  For laser processing, in addition to punching, where the beam spot diameter of the laser beam is approximately the diameter of the via hole, trepanning processing that processes a via hole with a diameter larger than the beam spot diameter by irradiating the laser while drawing the locus of the hole. There is. In particular, trepanning is a UV laser processing machine that excels at small-diameter processing, and has become an indispensable technique when processing via holes with large hole diameters. In trepanning processing, the processing locus is often drawn using a galvano scanner which is used for high-speed positioning by punching. In punching, the behavior along the path of moving between two points in step scanning that rapidly moves from one position to another is not regarded as important. On the other hand, in the trepanning process, since the trajectory is drawn, the behavior of the traveling route is also important, and high followability is required. However, it is difficult to achieve both high-precision positioning of punching and high followability of trepanning at high speed. Both the laser processing apparatuses described in Patent Document 1 and Patent Document 2 do not consider trepanning processing, and have a problem that they cannot sufficiently cope with via hole processing that diversifies from a small diameter to a large diameter.

  An object of the present invention is to provide a laser processing apparatus and method for solving the above-described problems and achieving both high precision positioning and high followability in both punching and trepanning.

  In order to solve the above-described problems, the laser processing apparatus of the present invention separately provides a scanner that performs a positioning operation with respect to a predetermined processing position on a printed circuit board and a scanner that performs a trepanning operation for drawing the outline of one via hole. It is characterized by.

  According to the described laser processing apparatus of the present invention, it is possible to improve processing throughput and hole shape in both punching and trepanning processing, and various hole processing from a small diameter to a large diameter is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of a laser processing apparatus according to a first embodiment of the present invention that can process two substrates in a time-sharing manner using light from one light emitting source. First, the optical path of laser light will be described.

The laser beam 2 emitted from the laser oscillator 1 enters the beam distribution shapers 4 and 5 through the mask 3 that determines the beam diameter (processing shape). The beam distribution shapers 4 and 5 have a function of switching the direction of the laser light 2 according to a command from a host control device (not shown) of the laser processing machine and a function of shaping the pulse waveform into a rectangular shape. When the beam distribution / shaping device 4 is in the ON state, the laser light 2 changes its traveling direction as the first processing beam 6 and enters the fixed mirror 9. When the beam distribution / shaping device 4 is in the OFF state, the laser light 2 travels straight and reaches the beam distribution / shaping device 5. The laser beam 2 incident on the beam distribution / shaping device 5 changes its traveling direction as the second processing beam 7 when the beam distribution / shaping device 5 is in the ON state, enters the fixed mirror 10, and goes straight as it is in the OFF state to block the light shield 8. To. Therefore, the first processing beam 6 and the second processing beam 7 can be switched in a time division manner by switching ON / OFF of the beam distribution shapers 4 and 5. First, the optical path of the first machining beam 6 will be described.

The first processed beam 6 emitted with the beam distribution and shaper 4 turned on is reflected by the fixed mirror 9, reflected by the first polarization beam splitter 13 through the half-wave plate 12, The light enters the biaxial scanner 14. The first biaxial scanner 14 functions as a fixed mirror during punching, and functions as a trepanning trajectory generation scanner during trepanning. The first processed beam 6 emitted from the first biaxial scanner 14 is reflected by the second polarizing beam splitter 15 and enters the second biaxial scanner 19 through the fixed mirrors 16 and 17. The angle incident on the fθ lens 21 is controlled by the second biaxial scanner 19 to irradiate a predetermined position of the substrate 24 placed on the XY stage 23 (processing area 50 × 50 mm square).

  Next, the optical path of the second machining beam 7 will be described. The second processed beam 7 that has traveled straight through the OFF beam distribution / shaping device 4 and whose direction has been changed by the ON-state distribution / shaping device 5 passes through the first polarizing beam splitter 13 via the fixed mirrors 10 and 11. By doing so, it is superimposed (combined) with the first processing beam 6 and enters the first biaxial scanner 14. The second processing beam 7 emitted from the first biaxial scanner 14 passes through the second polarization beam splitter 15, is separated from the first processing beam 6, and enters the fixed mirror 18. The second processing beam 7 reflected by the fixed mirror 18 is irradiated onto a predetermined position of the substrate 25 placed on the XY stage 23 by controlling the angle of incidence on the fθ lens 22 by the third biaxial scanner 20. (Processing area about 50 x 50 mm square).

  Here, the first biaxial scanner 14 includes a galvano scanner 14b to which a mirror 14a for oscillating the synthesized beam in the X axis direction on the substrate surface placed on the XY stage 23, and the Y axis direction. And a galvano scanner 14d to which a mirror 14c for shaking is attached.

The second biaxial scanner 19 includes a galvano scanner 19b to which a mirror 19a for oscillating the first machining beam 6 in the X axis direction with respect to the work area on the surface of the substrate 24 on the XY stage 23; The galvano scanner 19d is provided with a mirror 19c for swinging in the Y-axis direction. Similarly, the third biaxial scanner 20 is a galvano scanner to which a mirror 20a for oscillating the second machining beam 7 in the X-axis direction with respect to the work area on the surface of the substrate 25 on the XY stage 23 is attached. 20b and a galvano scanner 20d to which a mirror 20c for swinging in the Y-axis direction is attached.

  The XY stage 23 is configured to be movable in the XY directions by a drive mechanism (not shown). As shown in FIG. 4A, the substrate mounted on the XY stage (for example, the substrate 24) is processed in the processing region 26 by the second biaxial scanner 19 as shown in FIG. Move and position so that the Note that the relationship between the third biaxial scanner 20 and the substrate 25 is the same as that in FIG.

  Next, functions of the first polarizing beam splitter 13 and the second polarizing beam splitter 15 will be described. The polarization beam splitter has a characteristic of transmitting P-polarized light (light whose vibration direction is parallel to the paper surface) and reflecting S-polarized light (light whose vibration direction is perpendicular to the paper surface). Now, assuming that the laser beam 2 emitted from the laser oscillator 1 is P-polarized light, the second processed beam 7 remains P-polarized light, and thus passes through the first polarizing beam splitter 13 100%. On the other hand, since the first processed beam 6 is converted to S-polarized light by the half-wave plate 12, it is reflected 100% by the first polarizing beam splitter 13. Accordingly, since the first processing beam 6 is S-polarized light and the second processing beam 7 is P-polarized light, the optical paths of the two lights that have passed through different optical paths using the first polarizing beam splitter 13 are made coaxial without loss. can do. Therefore, the first machining beam 6 and the second machining beam 7 draw the same locus by the first biaxial scanner 14 and enter the second deflection beam splitter 15. Since the first machining beam 6 and the second machining beam are each kept in a deflected state after being emitted from the first biaxial scanner 14, the first S-polarized light incident on the second polarization beam splitter 15 is maintained. The processing beam 6 is 100% reflected, and the P-polarized second processing beam 7 is 100% transmitted.

  Next, the operation of the laser processing apparatus of the present invention will be described.

  First, punching will be described. In punching, the first two-axis scanner 14 is fixed at the center position and functions as a fixed mirror. In order to stabilize the light intensity and the beam profile of the laser beam 2, the laser oscillator 1 always performs pulse oscillation at the same repetition frequency. Now, the beam distribution shaper 4 is turned on for a predetermined time in response to a command from a host controller (not shown) to select the first processing beam 6 and irradiate the substrate 24 with a predetermined number of laser pulses. Punching.

At this time, the beam distribution / shaping device 5 is turned off, and at the same time, the positioning operation is completed so that the third biaxial scanner 20 can be operated to irradiate the second processing beam 7 to an arbitrary processing position of the substrate 25. Keep it. Next, when the beam distribution / shaping device 4 is turned off, the beam distribution / shaping device 5 is turned on and the machining beam 7 is selected, the positioning has already been completed with respect to an arbitrary position of the substrate 25. Punching can be performed by irradiating the number of laser pulses. At this time, the positioning operation is completed so that the second biaxial scanner 19 can irradiate the first machining beam 6 to the next machining position. 4B, the coordinates of the hole position are described in the processing area 26 (about 50 × 50 mm square) of the second biaxial scanner 19 and the third biaxial scanner 20, as shown in FIG. According to a certain processing program, for example, punching 28a can be performed on each of the substrates 24 and 25 with 100% processing energy of the laser beam 2 in the order indicated by the arrows in FIG. When the second biaxial scanner 19 and the third biaxial scanner 20 finish processing the substrate in a predetermined processing area, the XY stage 23 operates to move the substrate surface to the next processing region. During this time, both the beam distribution shapers 4 and 5 are kept OFF. For this reason, the laser beam 2 passes through the beam distribution shapers 4 and 5 almost 100% and is converted into heat by being absorbed by the light shield 8 as the light shield beam 29, so that the processing beam is irradiated onto the substrate. Absent.

  Next, the trepanning process will be described. The difference from the punching process is the function of the first biaxial scanner 14, and the other operations are the same as the punching process, and the description thereof will be omitted. In the trepanning process, the first biaxial scanner 14 continuously draws an arbitrary trepanning locus repeatedly. For example, as shown in FIG. 6A, a circular locus can be generated as shown in FIG. 6B by scanning the galvano scanners 14a and 14c with the same amplitude and shifting the phase by π / 2 rad. . Then, if the beam distribution shapers 4 and 5 are turned on for a predetermined time for completing the trepanning process on the substrates 24 and 25, for example, the coordinates of the hole positions as shown in FIG. According to the processing program, the trepanning process 28b can be performed on each of the substrates 24 and 25 with the processing energy of 100% of the laser beam 2 in the order indicated by the arrows in FIG.

  As described above, according to the laser processing apparatus of the present invention, by separately arranging a scanner that draws a trace of trepanning, it is possible to improve processing throughput and hole shape in both punching and trepanning. This makes it possible to drill various holes from small to large diameters.

  Next, a second embodiment of the present invention will be described. FIG. 2 is a block diagram showing the configuration of the laser machining apparatus according to the second embodiment of the present invention. First, the components of the second embodiment will be described. In FIG. 2, the same components as those in FIG. Here, the only newly added and modified component is that the beam distribution shaper 5 is deleted and the beam splitter 30 is used instead of the first polarization beam splitter.

  First, the optical path of laser light will be described.

  The laser beam 2 is emitted from the laser oscillator 1 and enters the beam distribution shaper 4 through the mask 3. The beam distribution / shaping device 4 has a function of switching the direction of the laser light 2 and a function of shaping the pulse waveform into a rectangular shape in response to a command from a host controller (not shown) of the laser processing machine. When the beam distribution / shaping device 4 is in the ON state, the laser beam 2 changes its traveling direction, and when it is in the OFF state, the laser beam 2 travels straight and reaches the light blocking body 8.

  The laser beam 2 enters the first biaxial scanner 14 via the fixed mirrors 9 and 10. The first biaxial scanner 14 functions as a fixed mirror during punching and as a trepanning trajectory generation scanner during trepanning. The laser beam 2 emitted from the first biaxial scanner 14 is split by the beam splitter 30 into a first processing beam 6 and a second processing beam 7 with a processing energy of 50%. Subsequent optical paths of the first machining beam 6 and the second machining beam 7 are the same as those in the first embodiment, and are omitted.

Next, the operation of the second embodiment of the present invention will be described in detail. First, punching will be described. In punching, the first two-axis scanner 14 is fixed at the center position and functions as a fixed mirror. In order to stabilize the light intensity and the beam profile of the laser beam 2, the laser oscillator 1 always performs pulse oscillation at the same repetition frequency. Now, the beam distribution / shaping device 4 is turned on for a predetermined time in response to a command from a host controller (not shown), and the laser beam 2 is divided into two by the beam splitter 30, and the first of the two divided beams is processed. The processing beam 6 is irradiated onto the substrate 24 and the second processing beam 7 is irradiated onto the substrate 25 simultaneously by a predetermined number of laser pulses. At this time, for example, according to the processing program in which the coordinates of the hole position are described, the substrate 24, 50% processing energy is irradiated by irradiating the laser beam 2 in the order shown by the arrows in FIG.
Punching 28a can be performed for each of 25.

  While the XY stage 23 is in operation, if the beam distribution / shaping device 4 is turned off, the laser light 2 passes through the beam distribution / shaping device 4 almost 100% and is absorbed by the light blocking body 8 as a light blocking beam 29. Thus, the substrate is not irradiated with the processing beam because it is converted into heat.

  Next, the trepanning process will be described. The only difference from the punching process is that the first biaxial scanner 14 always draws an arbitrary trepanning locus repeatedly, and the other operations are the same as the punching process, and the description thereof will be omitted. .

  Next, a third embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the laser machining apparatus according to the third embodiment of the present invention. In the above embodiments, two substrates are processed, but in this embodiment, two punching or two trepanning processes are simultaneously performed on one substrate. First, the components of the third embodiment will be described. In FIG. 3, the same reference numerals are used for the same components as in FIG. Here, the only newly added and modified components are the use of the beam splitter 30 instead of the first polarizing beam splitter and the fourth biaxial scanner 35 instead of the third biaxial scanner 20.

  First, the optical path of laser light will be described.

  The laser beam 2 is emitted from the laser oscillator 1 and enters the beam distribution shaper 4 through the mask 3. The beam distribution / shaping device 4 has a function of switching the direction of the laser light 2 and a function of shaping the pulse waveform into a rectangular shape in response to a command from a host controller (not shown) of the laser processing machine. When the beam distribution / shaping device 4 is in the ON state, the laser beam 2 changes its traveling direction, and when it is in the OFF state, the laser beam 2 travels straight and reaches the light blocking body 8.

  The laser 2 is incident on the first biaxial scanner 14 via the fixed mirror 9. The first biaxial scanner 14 functions as a fixed mirror during punching and as a trepanning trajectory generation scanner during trepanning. The laser beam 2 emitted from the first biaxial scanner 14 is split by the beam splitter 30 into a first processing beam 33 and a second processing beam 34. The first processed beam 33 is converted in the polarization direction by the half-wave plate 12, reflected by the polarization beam splitter 15 through the fixed mirrors 16 and 17, and incident on the fθ lens 21 by the second biaxial scanner 19. The angle to be controlled is controlled to irradiate a predetermined position of the substrate 24 placed on the XY stage 23 (processing area 50 × 50 mm square). On the other hand, the second machining beam 34 enters the fourth biaxial scanner 35. Here, the fourth biaxial scanner 35 has a galvano scanner 35b to which a mirror 35a for oscillating the second processing beam 34 in the X axis direction of the XY stage and a mirror 35c for oscillating in the Y axis direction are attached. The galvano scanner 35d. The second machining beam 34 scans only a slight angle range (for example, about 1 × 1 mm in the machining area) by the fourth biaxial scanner 35. The second processing beam 34 passes through the polarization beam splitter 15 and is irradiated onto the substrate 24. Accordingly, the first machining beam 33 is positioned at a position corresponding to the angle controlled by the second biaxial scanner 19, while the second machining beam 34 is aligned with the second biaxial scanner 19 and the fourth 2 axis. The axis scanner 35 is positioned at a position corresponding to the added angle. That is, assuming that the substrate 24, the processing area 26 of the first processing beam 33, and the processing area 36 of the second processing beam 34 as shown in FIG. 5A, the first as shown in FIG. 5B. The second machining beam 34 can be moved to an arbitrary position around the machining position 37a by the machining beam 33 (for example, about 1 × 1 mm). The scan range of the second machining beam 34 is narrowed because the installation position is away from the fθ lens 21, so that it does not fall within the effective diameter of the fθ lens 21 when the beam is scanned greatly.

  Next, the operation of the third embodiment of the present invention will be described in detail. First, punching will be described. In punching, the first two-axis scanner 14 is fixed at the center position and functions as a fixed mirror. In order to stabilize the light intensity and the beam profile of the laser beam 2, the laser oscillator 1 always performs pulse oscillation at the same repetition frequency. Now, the beam distribution shaper 4 is turned on only for a predetermined time in accordance with a command from a host controller (not shown), and the substrate 24 is formed by the first processing beam 33 and the second processing beam 34 obtained by dividing the laser light 2 into two. Is irradiated with a predetermined number of laser pulses. At this time, for example, as shown in FIG. 5B, two punching holes 37a and 38a are simultaneously processed in the order indicated by the arrows according to the processing program in which the coordinates of the hole positions are described. Note that while the processing in the processing area 27 of the second biaxial scanner 19 is completed and the XY stage 23 is operating to the next processing region, the beam distribution / shaping device 4 can be turned off. Since the laser light 2 is almost 100% transmitted through the beam distribution shaper 4 and absorbed by the light shielding body 8 as the light shielding beam 29, it is converted into heat, so that the processing beam is not irradiated onto the substrate.

  Next, the trepanning process will be described. The difference from the punching process is the function of the first biaxial scanner 14, and the other operations are the same as the punching process, and the description thereof will be omitted. In the trepanning process, the first biaxial scanner 14 continuously draws an arbitrary trepanning locus repeatedly. Then, if the beam distribution shaper 4 is turned on for a predetermined time when the trepanning process is completed for the substrate 24, two holes are simultaneously formed in the substrate 24 according to the processing program in which the coordinates of the hole positions are described. The trepanning holes 37b and 38b can be machined in the order indicated by the arrows in FIG.

  In the configuration described above, punching and trepanning can be performed with high accuracy in a short time at two locations on a single substrate.

  The present invention uses proven components, and in view of the effects, the present invention is highly likely to be sufficiently utilized particularly in the field related to processing of via holes in a printed wiring board.

It is a block diagram of the laser processing apparatus which concerns on 1st Example of this invention. It is a block diagram of the laser processing apparatus which concerns on the 2nd Example of this invention. It is a block diagram of the laser processing apparatus which concerns on the 3rd Example of this invention. It is explanatory drawing of the process area which concerns on the 1st, 2nd Example of this invention. It is explanatory drawing of the process area which concerns on the 3rd Example of this invention. It is a figure which shows an example of the trepanning locus | trajectory of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser oscillator, 2 ... Laser beam, 3 ... Mask, 13 ... 1st polarizing beam splitter, 14 ... 1st biaxial scanner, 15 ... 2nd polarizing beam splitter, 19 ... 2nd biaxial scanner, 20 ... third biaxial scanner, 21, 22 ... fθ lens, 24, 25 ... substrate, 35 ... fourth biaxial scanner.

Claims (5)

A laser oscillator for oscillating a laser beam, a mask for determining a machining shape, beam switching means for time-dividing the laser beam, a beam scanning optical system for scanning the workpiece with the time-divided laser beam, In a laser processing apparatus having a processing head composed of a processing lens for transferring the shape of a mask onto a processing target for the number of time-divided beams, and supplying a laser beam to any one of the processing heads,
A laser processing apparatus comprising: means for superimposing time-divided laser light paths; means for generating a trepanning trajectory; and means for re-dividing the superimposed light paths between the beam switching means and the processing head. A laser oscillator that oscillates laser light, a mask that determines a processing shape, a beam splitter that divides the laser light, a beam scan optical system that scans the divided laser light onto a processing object, and a shape of the mask In a laser processing apparatus having a processing head composed of a processing lens for transferring a laser beam onto a processing object, and supplying laser light to any one of the processing heads.
A laser processing apparatus, wherein means for generating a trepanning trajectory is disposed between the mask and the beam splitter. A laser oscillator that oscillates a laser beam, a mask that determines a machining shape, a beam splitter that divides the laser beam, a polarization beam splitter that superimposes the divided laser beam, and a scanning object that scans the laser beam. In a laser processing apparatus having a beam scanning optical system and processing by making a plurality of laser beams incident on one processing lens for transferring the shape of the mask onto a processing target,
A laser processing apparatus, wherein means for generating a trepanning trajectory is disposed between the mask and the beam splitter.   The laser processing apparatus according to claim 1, wherein a biaxial galvano scanner is used as the means for generating the trepanning trajectory. 4. The laser processing apparatus according to claim 1, wherein a polarization beam splitter is used as means for superimposing the laser light.

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