JP2004090062A - Laser beam machining device, machining method, and method for manufacturing circuit board by using the machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining device having high machining accuracy with a simple and compact configuration. <P>SOLUTION: The laser beam machining device comprises a fixed optical system comprising a laser beam oscillator 2 and a collimating means 27 to form laser beams to be parallel ones, a driven optical system having a scanner mirror 28 driven along the optical axis of laser beams oscillated from the collimating means, and a stage 4 to support ceramic green sheets 3 in a driving manner along a predetermined axis. The optical axis is perpendicular to the predetermined axis with a predetermined distance therebetween. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a processing apparatus and a processing method for performing processing such as drilling, cutting, and printing on a workpiece using a laser beam. More specifically, the present invention relates to an apparatus and a method for efficiently drilling a so-called ceramic green sheet made of ceramics, and further relates to a method for manufacturing a circuit board by processing the green sheet. is there.
[0002]
[Prior art]
Since circuit boards made of ceramics are superior in heat resistance and durability to general resin boards, their use in portable information terminal devices and the like is expanding. At the same time, for the purpose of high integration, there is an increasing number of cases where a function as a circuit is added to the ceramic substrate itself and the substrate is laminated to be used as a multilayer substrate. The green sheet is a common name for a ceramic substrate before firing, and the substrate is generally subjected to perforation processing for forming a multilayer wiring at the stage of the green sheet.
[0003]
In these drilling processes and the like, there are an increasing number of cases where laser light is used from the viewpoint of changing the processing speed, the shape of the processed hole, or the ease of obtaining a processed hole with high roundness. An outline of a conventional example of an apparatus for drilling various workpieces, particularly ceramic green sheets, using laser light will be described below with reference to the drawings. FIG. 2 shows a schematic configuration of a main part in a conventional laser processing apparatus.
[0004]
The apparatus includes a laser oscillator 1 that transmits a processing laser beam, a guide laser oscillation device 2 that transmits a guide laser, an optical that shapes the guide laser beam and the processing laser beam and guides them to a predetermined position on the workpiece 3. The system 20, the XY stage 4 on which the workpiece 3 is placed and moved in the XY direction, the shape of the guide laser beam or the like reaching the workpiece 3 or the shape of the machining hole is captured as an image, and the workpiece is processed. It comprises a camera 5 used for positioning an object and a control system 10 that drives these components. As the guide laser, for example, red light or the like is used, which is projected on the workpiece in advance, and the position for projecting the actual processing laser from the projection position, projection shape, or the like, or the shape at the time of projection, etc. Correction is performed.
[0005]
The optical system 20 includes total reflection mirrors 21, 23 and 26, a dichroic mirror 22, a mask 24, a collimator lens 27, an XY galvano scanner mirror 28, and an fθ lens 29. Laser light emitted from the laser oscillator 1 changes its direction toward the dichroic mirror 22 by the total reflection mirror 21, passes through the dichroic mirror 22 from the back surface, and further toward the mask 24 by the total reflection mirror 23 again. change. The direction of the guide laser beam emitted from the guide laser oscillator 2 is changed by the dichroic mirror 22 so as to travel on the same optical axis as the processing laser beam.
[0006]
When the processing laser light and the guide laser light pass through the opening 24a when passing through the mask 24, the shape thereof is shaped so as to correspond to the shape of the processing hole such as a shape close to a perfect circle. Generally, the laser light after passing through (passing through) the mask has a certain degree of expansion, and therefore needs to be reshaped as parallel light by a collimator lens or the like. For this reason, the direction of the shaped laser light is changed again by the total reflection mirror 26 so that the light enters the collimator lens 28. The irradiation position of the laser beam converted into parallel light through the collimator lens 27 is moved by the XY galvano scanner mirror 28 and the fθ lens 29 so as to reach an arbitrary processing position on the workpiece 3. The XY galvano scanner mirror and the fθ lens integrally function as an optical system for controlling the irradiation position of the laser light.
[0007]
The control system 10 includes a galvano scanner control unit 12, an image processing unit 13, a drive system control unit 14, and a main control unit that controls these units and controls a laser oscillator and the like in synchronization with the control. The galvano scanner control unit 12 is connected to the XY galvano scanner mirror 28, and controls the irradiation position of the laser beam by controlling these. The image processing unit 13 is connected to the camera 5 and confirms the state of the processing hole, the position accuracy, and the like from the image obtained by the camera, and sends information related to the number of pulses and the intensity of the laser light to the main control unit. Output. The drive system processing unit 14 drives the XY stage 4 and changes the position of the workpiece 3 so that the planned drilling position on the workpiece is within the laser beam irradiable range by the galvano scanner mirror. . The apparatus has a configuration in which the shape of the mask 24 is projected onto the surface of the workpiece 3 at an arbitrary reduction ratio, thereby obtaining a hole shape with less taper in the cross section of the processed hole and close to a perfect circle.
[0008]
[Problems to be solved by the invention]
The position accuracy of the processed hole required for the apparatus becomes higher with the downsizing of electronic parts and the like, and in recent years, a value within ± 30 μm is required. This required position accuracy and the shape accuracy that will be required at the same time are expected to become even higher. For this reason, the laser beam irradiable range by the galvano scanner mirror described above tends to be narrowed in order to satisfy this positional accuracy and the like. Here, high precision is required for the processing apparatus, and at the same time, the workpiece tends to become larger from the viewpoint of increasing the processing efficiency. In consideration of the above matters, in the above-described processing apparatus, the size of the workpiece is increased and the above-described positional accuracy is dealt with by increasing the size of the XY stage and moving the workpiece largely.
[0009]
In recent years, for the purpose of further improving processing efficiency, a method has been adopted in which a green sheet, which is a workpiece, is placed on a conveying sheet and the green sheet is efficiently conveyed by winding the sheet. Yes. FIGS. 3 and 4 show the concept of an apparatus configuration in the case where the green sheet is subjected to processing such as punching while winding such a conveying sheet on a reel. In these drawings, for the sake of simplification, the laser light oscillator or the optical system is omitted, and only the XY galvano scanner mirror 28 is representatively shown. Usually, the configuration in which these descriptions are omitted is integrally fixed and supported at the position of the XY galvano scanner mirror 28.
[0010]
Usually, the conveyance sheet 8 is fixed to the XY stage 4 by vacuum suction or the like, and by driving the XY stage 4 in this state, the portion to be processed on the workpiece 3 can be irradiated with laser light. Moved to range. However, when only a part of the transport sheet 8 is moved in a direction perpendicular to the transport direction, stress is applied to the transport sheet 8 or, in some cases, the ceramic green sheet as the workpiece 3 with the part as the center. End up. For this reason, the sheet may be damaged or the fixed state of the sheet may become unstable, and the position accuracy may be deteriorated. Therefore, in the apparatus configuration of FIG. 3, the reels 35 and 36 for winding the conveyance sheet 8 are driven in accordance with the movement of the XY stage 4. In this case, a configuration for driving the reel is required, and the device configuration becomes complicated.
[0011]
Further, as shown in FIG. 4, the configuration is simplified and the conveying sheet is provided by widening the interval between the reels 35 and 36 and the XY stage 4 and providing the buffer area 9 in which the conveying sheet 8 is slackened in this portion. In some cases, it is possible to reduce the stress on the like. However, this configuration cannot eliminate stress, and cannot eliminate the possibility of deterioration in position accuracy. Further, the configuration shown in FIG. 3 or FIG. 4 always has a problem that the device configuration is necessarily increased in size.
[0012]
The present invention has been made in view of the above problems, and has a simple structure, a ceramic green sheet placed on a conveyance sheet, etc. without increasing the size and maintaining high positional accuracy. An object of the present invention is to provide a laser processing apparatus or a processing method for performing a drilling process or the like. Furthermore, it aims at manufacturing the circuit board which consists of a ceramic green sheet with the high positional accuracy using the said method.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, a laser processing apparatus according to the present invention is a laser processing apparatus that irradiates a workpiece with laser light and processes the irradiated portion, and a laser oscillator that emits laser light; A fixed optical system having collimating means for converting the laser light into parallel laser light, and a driven optical system having scanner mirror means for receiving and reflecting the parallel laser light to a predetermined position; And a stage capable of supporting the workpiece and moving the workpiece along a predetermined axis, and the optical axis of the laser beam composed of parallel light after passing through the collimating means is from the predetermined axis. The driven optical system has a specific distance and is perpendicular to a predetermined axis, and the driven optical system is driven along the optical axis.
[0014]
The above apparatus further includes a frame that supports the fixed optical system and at the same time supports the driven optical system so as to be driven along the optical axis. The frame has a substantially arch shape having legs on both sides of a predetermined axis. It preferably has a structure.
[0015]
In order to solve the above problems, a laser processing method according to the present invention is a laser processing method for irradiating a workpiece with a laser beam and processing the irradiated portion, which is emitted from a laser oscillator. The irradiated laser light is converted into parallel laser light and guided to a mirror means whose irradiation position can be scanned along a predetermined optical axis, and the laser light made up of parallel light is projected onto a predetermined area of the workpiece by the mirror means. It is characterized in that it is guided and processed, and the mirror means is driven along a predetermined optical axis, and then the laser beam composed of parallel light is guided to another region different from the predetermined region in the workpiece to perform the processing. Yes.
[0016]
In the above method, before and after processing a predetermined region or other region in the workpiece, the mirror means is perpendicular to the optical axis separately from driving along the predetermined optical axis. The workpiece is preferably driven in the direction.
[0017]
In order to solve the above-described problem, the circuit board manufacturing method according to the present invention scans an irradiation position along a predetermined optical axis by using laser light emitted from a laser oscillator as laser light composed of parallel light. A first drilling step in which a laser beam composed of parallel light is guided to a predetermined region on the ceramic green sheet by the mirror unit and drilled, and the mirror unit is set to a predetermined optical axis. A second drilling step in which a laser beam composed of parallel light is guided to another region different from a predetermined region in the ceramic green sheet to perform drilling after driving along the first and second holes; And a step of injecting a conductive paste into the hole formed on the ceramic green sheet by the step.
[0018]
The method preferably further includes a step of driving the ceramic green sheet along an optical axis perpendicular to the predetermined optical axis, and further repeating the first and second drilling steps.
[0019]
【Example】
FIG. 1 shows a schematic configuration of a laser processing apparatus according to the present invention. In addition, about the structure which fulfill | performs the same effect | action as each structure in the conventional apparatus shown in FIG. 2, the same referential mark is used and it abbreviate | omits about the description. A ceramic green sheet as a workpiece is placed on a conveyance sheet 31 and is moved by rotating the first and second reels 35 and 36 around which the conveyance sheet 8 is wound. Has been. The stage 34 can fix the sheet by vacuum suction or the like, and can be driven only in the X direction (predetermined direction) coinciding with the sheet conveyance direction indicated by the arrow X in the drawing.
[0020]
In this embodiment, the optical system that emits a laser and guides it to a predetermined position on the green sheet 3 is separated into a fixed portion 41 that is a fixed optical system and a drive portion 42 that is a driven optical system. The fixing unit 41 is configured from the laser oscillator 1 and the guide laser oscillator 12 to a collimator lens 27 that is a collimating unit that converts the laser light into parallel light, and is substantially integrated and fixed to a frame 45 described later. Has been. Unlike the configuration shown in the conventional example, the fixed portion 41 is provided with total reflection mirrors 31 and 32. These mirrors are added to allow laser light to enter the collimator lens 27 from a predetermined direction. It has been done.
[0021]
The drive unit 42 includes an XY galvano scanner mirror 28 that is a mirror means that receives laser light and scans it to a predetermined irradiation position, and an fθ lens 29 that adjusts the light diameter of the irradiated laser light. Yes. The drive unit 42 is driven on a frame in a Y direction indicated by an arrow Y in the figure perpendicular to the sheet conveyance direction by a drive device (not shown). More specifically, the drive unit 42 is driven in parallel with the optical axis of the laser beam guided to the drive unit via the collimator lens 27. In other words, the drive axis of the scanner mirror that coincides with the optical axis of the laser beam after passing through the collimator 27 and the drive axis along which the green sheet 3 is conveyed have a specific distance and a vertical positional relationship. Have.
[0022]
Usually, an optical fiber is used when laser light is guided to a driven optical system. However, when the driving amount of the optical system is large and the bending amount of the optical fiber becomes large, there is a possibility that the optical fiber is damaged by bending stress. Accordingly, it is not preferable to apply an optical fiber to the present apparatus which has a high probability of increasing the size of the workpiece and increasing the driving amount of the driven optical system. An optical fiber is suitable for transmitting laser light having a specific wavelength according to its characteristics, but the transmission efficiency of laser light having other wavelengths is often reduced. For this reason, by using an optical fiber, the wavelength region of usable laser light is specified, and the versatility of the apparatus is also lowered.
[0023]
In the present invention, the collimator lens 27 is arranged at the laser light emission portion from the fixed portion 41 so that the laser light is converted into parallel light, and this parallel light is received by the XY galvano scanner mirror 28. As long as the XY galvano scanner mirror 28 accurately moves on the optical axis of the laser beam to receive the parallel laser beam, the galvano scanner mirror 28 has a constant intensity, a constant energy distribution, and a constant beam irradiation range. Laser light will be guided.
[0024]
The laser light usually includes diffracted light or higher-order components generated at the time of irradiation at the initial stage of irradiation from the laser oscillator. For this reason, when light condensing with a lens is performed, the light condensing property is deteriorated, or the energy density around the condensing point is nonuniform. In order to prevent such a situation, many measures such as setting the optical path length to a certain level or more are employed. However, in the present invention, since the distance from the collimator lens to the drive unit changes greatly, it is considered appropriate to take the conventional measures to reduce the influence because the apparatus is increased in size. I will not. Therefore, in this embodiment, by setting the mask 24 and setting the optical path length from the oscillator to the collimator lens to an appropriate value in advance, the influence of these diffracted light or the like does not occur after the collimator lens. Even so, it will be insignificant.
[0025]
By adopting this configuration, it is possible to always guide laser light having a constant energy distribution to the drive unit without being affected by the distance between the collimator lens 27 and the drive unit 42 (XY galvano scanner mirror). Therefore, unlike the case where an optical fiber or the like is used, it is not necessary to mechanically connect the fixed portion and the drive portion, and it is possible to easily cope with the enlargement of the drive area or the increase in the drive speed in the drive portion. Further, laser light in all wavelength ranges, for example, from a carbon dioxide gas laser having a wavelength of 10.6 μm to an ultraviolet laser having a wavelength of 200 μm can be easily used only by exchanging the laser oscillator.
[0026]
In carrying out the present invention, the XY galvano scanner mirror must always receive laser light at a predetermined site. For this reason, the drive unit is required to maintain high parallelism and high straightness with respect to the optical axis of the laser beam during driving, and to minimize the occurrence of yawing and the like during driving. For example, when the fθ lens is tilted by 0.1 degrees due to yawing or the like, the laser irradiation position on the workpiece may be shifted by several μm.
[0027]
As a specification required for carrying out the present invention, for example, the straightness described above is preferably suppressed to 5 μm or less. Therefore, in this embodiment, the laser oscillator, the optical system, and the like are not arranged on the conventional cantilever frame but on the upper part of the gate-shaped frame 45 having a more rigid shape. Furthermore, since it is necessary to increase the rigidity of the frame 45 itself, the frame is configured as an integral structure by casting. In this embodiment, a cast frame is used. However, a frame formed by welding an iron pipe or the like may be used as long as it has rigidity capable of satisfying specifications such as straightness. .
[0028]
In addition, it is preferable that the apparatus can detect or correct changes such as straightness at any time during installation or normal use. In this embodiment, it is preferable to install a closed type linear scale for the X-axis stage and the drive unit, and to control the drive unit and the like while always feeding back the position. In this detection process, the camera 5 arranged in the drive unit may be used.
[0029]
Next, a process for punching the ceramic green sheet 3 placed on the conveying sheet 8 using the laser processing apparatus according to the present invention, that is, a method for manufacturing a circuit board will be described. First, the take-up reels 35 and 36 of the conveyance sheet 8 are rotated, and the green sheet 3 to be processed in this process on the conveyance sheet 8 stops at a predetermined position on the X stage 34 at the initial position. Is done. At the stop position, the green sheet 3 is adsorbed and fixed on the X stage 34 together with the conveying sheet 8 by, for example, vacuum adsorption.
[0030]
Subsequently, a reference mark (not shown) provided on the fixed green sheet 3 is imaged by the camera 5 attached to the drive unit 42 at the initial position. By performing image processing on the captured reference mark, a correction coefficient regarding the stop position of the X stage 34 and the drive unit 42 is calculated, and the calculation result is stored in a memory (not shown). Based on the stored correction coefficient, the X stage 34 and the drive unit 42 are driven to match the processable area of the XY galvano scanner mirror 28 with the desired process area.
[0031]
Thereafter, the galvano scanner mirror 28 is driven so that the irradiation position of the laser beam reaches a predetermined processing position in accordance with a preset processing pattern, laser processing conditions, and the like. Here, ON / OFF control of the laser oscillator 1 is performed, and laser light is irradiated onto the green sheet 3 to perform drilling. Further, ON / OFF control of the laser oscillator 1 and driving of the galvano scanner mirror 28 are continuously performed to perform drilling in a desired processing region.
[0032]
After completion of drilling in the desired machining area, the X stage 34 or the drive unit 42 is driven alone or both are driven to match the new machining area with the workable area. Subsequently, drilling in the processing area is performed according to the above-described procedure. By repeating the above processing procedure a plurality of times, the drilling process is performed for all desired regions on the green sheet 3. After the perforating process is completed, the fixed state of the green sheet 3 and the transport sheet 8 by the X stage 34 is released, and a new green sheet is transported to a predetermined fixed position by the transport reels 35 and 36. Hereinafter, the procedure described here is repeated again, and the green sheet is punched.
[0033]
Through the above steps, through holes and the like are formed at predetermined positions on the ceramic green sheet. A conductive paste serving as an electrode is inserted into the through-hole and the like, and these green sheets are further laminated and cut as necessary, and then baked to form a circuit board.
[0034]
By implementing the present invention, it becomes possible to construct a laser processing apparatus having a significantly reduced apparatus installation area as compared with the conventional laser processing apparatus shown in FIG. 3 or 4. In addition, the workpiece conveying system can be simplified and the so-called independent operation in the Y-axis direction can be achieved, and the process time can be greatly reduced. Specifically, when the laser processing apparatus according to the present invention is used for actual processing according to the above-described procedure, the processing time is shortened by 10% or more compared to the conventional processing apparatus shown in FIG. Was possible.
[0035]
In the above-described embodiment, the configuration of the optical system in the fixing unit is illustrated, but these are merely examples. Therefore, it is possible to use optical systems having various configurations, such as the use of a plurality of masks, the addition of further optical elements such as a homogenizer, and the combined use of a plurality of optical path systems that enable the introduction of laser beams having different characteristics. Is possible. Although the type of the collimator lens 27 is not particularly described, for example, a concave lens may be used in order to eliminate the expansion of the laser beam generated by the mask. That is, as long as a laser beam composed of parallel light can be obtained when the collimator lens is emitted, various lenses such as a concave lens, a convex lens, or a combination of a plurality of these lenses can be used. Is possible. Furthermore, although an XY galvano scanner mirror is used as the scanable mirror means, it is preferable to use a digital scanner mirror and various scanable mirror means according to the required accuracy.
[0036]
In this embodiment, the frame itself is not provided with any correction function in the X-axis direction with respect to the drive unit. However, a correction mechanism is added to the configuration of a rail or the like that supports the drive unit and regulates the movement of the drive unit in the Y direction so that the parallelism between the Y axis and the laser beam optical axis can be finely adjusted. Also good. In the present embodiment, the workpiece is placed on a conveying sheet that is continuously wound up. However, the shape of the workpiece or the conveyance format is not limited to this, and a configuration may be adopted in which card-like workpieces are individually conveyed onto the X stage and processed. Further, the present embodiment is an example of drilling a workpiece, but the present invention is not limited to this, and the present invention is not limited to this, but a processing apparatus that performs various processes such as cutting and printing on the workpiece. It may be applied to.
[0037]
[Effect of the present invention]
By carrying out the present invention, when processing a continuous sheet-like workpiece or a workpiece having a large area, the workpiece is processed at high speed and with high accuracy by a transport system having a simple configuration. It becomes possible. In addition, it is possible to simultaneously reduce the size of the processing apparatus and reduce the cost when constructing the apparatus.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a laser processing apparatus according to the present invention.
FIG. 2 is a diagram showing a schematic configuration of a conventionally used laser processing apparatus.
FIG. 3 is a diagram showing a schematic configuration of a conventionally used laser processing apparatus.
FIG. 4 is a diagram showing a schematic configuration of a conventionally used laser processing apparatus.
[Explanation of symbols]
1 Laser Oscillator 2 Guide Laser Oscillator 3 Workpiece (Ceramic Green Sheet)
4 XY stage 5 Camera 8 Transport sheet 9 Buffer area 10 Control system 11 Control unit 12 Galvano scanner control unit 13 Image processing unit 14 Drive system control units 21, 23, 26, 31, 32 Total reflection mirror 22 Dichroic mirror 24 Mask 27 Collimator lens 28 XY galvano scanner mirror 29 fθ lens 34 X stage 35, 36 Transport reel 41 Fixed portion 42 Drive portion 45 Frame

Claims (6)

A laser processing apparatus for irradiating a workpiece with laser light and processing the irradiated portion,
A fixed optical system having a laser oscillator that emits laser light, and collimating means that converts the laser light into parallel laser light; and
A driven optical system having scanner mirror means for receiving the laser beam composed of the parallel light and reflecting the laser beam to a predetermined position;
A stage capable of supporting the workpiece and moving the workpiece along a predetermined axis;
The optical axis of the laser beam composed of the parallel light after passing through the collimating means is in a positional relationship having a specific distance from the predetermined axis and perpendicular to the predetermined axis, and the driven The laser processing apparatus, wherein the optical system is driven along the optical axis. The frame further includes a frame that supports the fixed optical system and supports the driven optical system so as to be driven along the optical axis, and the frame has a substantially arch structure having legs on both sides of the predetermined axis. The laser processing apparatus according to claim 1, comprising: A laser processing method for irradiating a workpiece with laser light and processing the irradiated portion,
The laser light emitted from the laser oscillator is converted into parallel laser light and guided to a mirror means whose irradiation position can be scanned along a predetermined optical axis.
Laser light comprising the parallel light is guided to a predetermined region of the workpiece by the mirror means, and the processing is performed.
After the mirror means is driven along the predetermined optical axis, the laser beam composed of the parallel light is guided to another region different from the predetermined region in the workpiece to perform the processing. Laser processing method. Before and after applying the processing to the predetermined region or the other region of the workpiece, the mirror means is perpendicular to the optical axis separately from driving along the predetermined optical axis. The laser processing method according to claim 3, wherein the workpiece is driven in a direction. A circuit board manufacturing method comprising:
The laser light emitted from the laser oscillator is converted into parallel laser light and guided to a mirror means whose irradiation position can be scanned along a predetermined optical axis.
A first drilling step of performing drilling by guiding the laser beam composed of the parallel light onto a predetermined region on the ceramic green sheet by the mirror means;
After the mirror means is driven along the predetermined optical axis, a laser beam composed of the parallel light is guided to another region different from the predetermined region in the ceramic green sheet to perform the drilling process. Drilling process,
And a step of injecting a conductive paste into the holes formed on the ceramic green sheet by the first and second hole forming steps. 6. The circuit according to claim 5, further comprising a step of driving the ceramic green sheet along an optical axis perpendicular to the predetermined optical axis, and further repeating the first and second drilling steps. A method for manufacturing a substrate.

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