JP2005095949A - Laser beam working device and laser beam working method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam working device which has a simple constitution without bringing about a large scale nor a high cost, which copes with reeled continuous ceramic green sheet being a workpiece, and in which correction in a rotating direction is made possible and which can work a plurality of through-holes at high positional precision, and to provide a laser beam working method. <P>SOLUTION: In the laser beam working device and the laser beam working method, a mask for forming the laser beam into a prescribed shape and a diffraction element for dividing the laser beam passed through the mask into a plurality of beams are provided on a beam path from the laser beam source to the workpiece, and the irradiation position of the plurality of divided beams is changed by rotating the above diffraction element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly, to a laser processing apparatus and a laser processing method for drilling an electronic component.

  Conventionally, a laser processing apparatus that makes use of the coherency of a laser with respect to an electronic component, such as a green sheet, and branches a laser beam by using a diffraction phenomenon such as a diffraction element or a hologram element to simultaneously open a plurality of holes. Laser processing methods are known.

  FIG. 6 shows a conventional laser processing apparatus 101, (a) is a configuration diagram of the laser processing apparatus 101, and (b) is a diagram showing a processing pattern of the green sheet 135.

  In the laser processing apparatus 101 in FIG. 6A, a laser beam 104 emitted from a laser oscillator 145 such as an excimer laser is branched by a hologram 103. The branched laser beam 104 is condensed by the condensing lens 110 and irradiated onto the mask 113. Further, the mask pattern image formed by the laser beam passing through the opening of the mask 113 is formed as a transfer image on the green sheet 135 by the transfer lens 129, and the hole processing of the green sheet 135 is performed. FIG. 6B shows a green sheet 135 in which a through hole 136 is formed by the laser processing apparatus 101 (see Patent Document 1 or 2).

  FIG. 7 shows another conventional laser processing apparatus, (a) is a configuration diagram of the laser processing apparatus 201, and (b) is a diagram showing a processing pattern of a green sheet.

  Similar to FIG. 6, the laser processing apparatus 201 radiates a laser beam 204 from the laser oscillator 245 to process the through hole 236 in the green sheet 235. The optical system of the laser processing apparatus 201 includes a diffraction element 203 for separating the laser beam into a uniform shape and size from the laser oscillator side, xy galvano scan mirrors 231 and 232 for oscillating the laser beam in the xy direction, a laser beam. A condensing lens 229 for condensing light and a ceramic green sheet 235 as a workpiece placed on an xy table (not shown) are disposed.

  In the above configuration, the laser beam 204 emitted from the laser oscillator 245 passes through the diffraction element 203. The laser beam 204 that has passed through the diffraction element 203 is split into a plurality of laser beams corresponding to the shape and size of the through hole 236 formed in the ceramic green sheet 235. The laser beam dispersed by the diffraction element 203 is reflected by the xy galvano scan mirrors 231 and 232 and enters the condenser lens 229. Further, the laser beam condensed through the condensing lens 229 is irradiated on the green sheet 235 to perforate the through hole 236. In the above configuration, the reflection angles of the xy galvano scan mirrors 231 and 232 are changed, and the through holes 236 are formed at different positions of the green sheet 235. FIG. 7B shows a green sheet 235 having a through hole 236 by the laser processing apparatus 201 (see Patent Document 3).

JP-A-9-248686 (paragraph numbers [0038] to [0044], FIGS. 1 to 2) JP 2002-228818 A (paragraph numbers [0011] to [0012], FIG. 1) JP 2000-280225 A (paragraph numbers [0043] to [0052], FIGS. 1 to 2)

  Although not explicitly disclosed in the publication, a conventional laser processing apparatus 101 as shown in FIG. 6 is normally provided with an xy stage that can move in a two-dimensional direction. The green sheet 135 is placed on the xy stage, and the green sheet 135 is placed at an appropriate position by appropriately moving the xy stage.

  However, for example, when the y axis 178 of the y stage of the laser processing apparatus 101 and the longitudinal axis 176 of the actual green sheet 135 are deviated, that is, when the angle γ is deviated around the intersection O of both axes. It is necessary to correct the machining position.

  When one through hole is formed by one irradiation, the xy stage can be moved as appropriate, and the irradiation can be performed by correcting the processing position. However, when a plurality of through holes 136 are simultaneously drilled by one irradiation, even if one through hole 136 is corrected by moving the xy axis, the other two through holes 136 are in a predetermined drilling position. It will deviate from. Therefore, it is necessary to align the y axis 178 of the processing coordinates and the longitudinal axis 176 of the green sheet by shifting the entire laser processing apparatus 101 or the green sheet by the angle γ.

  However, providing the laser processing apparatus 101 with a mechanism for rotating the entire optical system including the hologram element 103, the condensing lens 110, the mask 113, and the transfer lens 129 by the angle γ complicates the structure and increases the cost. Not practical.

  Further, when the workpiece is a continuous reel-like ceramic green sheet, even if a rotation mechanism is added to the xy stage, the laser processing apparatus 101 becomes large and complicated, which increases costs and is difficult to realize. It was.

  Similar to the conventional example of FIG. 6, the laser processing apparatus 201 shown in FIG. 7A performs laser processing by placing a green sheet 235 as a workpiece on an xy stage (not shown). When one through-hole is formed by one irradiation, the xy stage can be moved and corrected to a predetermined processing position for irradiation. However, when a plurality of through holes 236 are simultaneously drilled by one irradiation as shown in FIG. 7B, even if one through hole 236 is corrected by moving the xy stage, the other two through holes 236 deviates from a predetermined drilling position. Therefore, it is necessary to align the y axis 278 of the processing coordinates and the longitudinal axis 276 of the green sheet by shifting the entire laser processing apparatus 201 or the green sheet 235 by the angle δ.

  However, providing the laser machining apparatus 201 with a rotation mechanism leads to an increase in the size and cost of the apparatus. In addition, when the green sheet is not a card-like green sheet but a continuous reel, it is necessary to incorporate a rotation mechanism in the entire green sheet conveying apparatus, resulting in a complicated structure and high cost. It wasn't.

  Accordingly, the present invention provides a simple configuration that does not lead to an increase in size and cost of a laser processing apparatus, and a plurality of through-holes with high positional accuracy even when the ceramic green sheet as a workpiece is a continuous reel. An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of simultaneously processing the above.

  In order to achieve the above object, a first aspect of the laser beam processing apparatus of the present invention includes a mask for forming a laser beam into a predetermined shape on an optical path from a laser source to a workpiece, and passing through the mask. And a diffractive element for branching the laser beam into a plurality of beams, and the diffractive element is provided with driving means for rotating the diffractive element.

  Furthermore, in the second aspect of the laser beam processing apparatus of the present invention, the workpiece is a continuous reel-shaped member.

  According to the laser beam processing method of the present invention, on the optical path from the laser source to the workpiece, the laser beam is passed through the mask, the laser beam is shaped into a predetermined shape, and the laser beam is incident on the diffraction element. This is a laser processing method in which the irradiation position of the plurality of beams is changed by rotating the diffraction element.

  With the above laser processing apparatus and processing method, it is possible to correct the irradiation position of the laser beam by rotating the diffraction element.

  In the above laser beam processing apparatus and laser beam processing method, the diffraction element used for branching the laser beam has a function of branching the incident laser beam into a plurality of beams having a uniform shape and size. There is no limitation to a diffraction element having a specific shape or size.

  In this specification, “rotate the diffraction element” means that the diffraction element is rotated in a plane perpendicular to the optical axis with a predetermined point as the rotation center. For example, the rotation of the diffraction element in a plane perpendicular to the optical axis with the branch center of the diffraction element as the rotation center, or the diffraction element in a plane perpendicular to the optical axis by shifting the rotation center from the branch center This is called rotation.

  According to the laser processing apparatus and the laser processing method of the present invention, the workpiece is inclined when the continuous reel-like member that is the workpiece (work) is supplied by providing the diffraction element with the rotating means. However, by correcting the inclination and irradiating the laser beam, it is not necessary to move the workpiece, and high-precision laser processing is possible.

  In addition, since the mask and the diffractive element are arranged in this order from the light source side on the optical path, the size and shape of the hole to be drilled can be freely changed by changing the mask, thereby increasing the degree of freedom of processing. It becomes possible.

  Hereinafter, embodiments of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a basic configuration diagram of a laser processing apparatus 1 according to the present invention. The laser processing apparatus 1 includes a beam generator 2 having a laser oscillator 45 and a guide laser oscillator 43, an optical system 6 for guiding the laser beam to a green sheet 35 as a workpiece, an x galvano scan 31, a y galvano scan 47, and the like. It comprises a support frame 33 for placing and a supply unit 8 for conveying the ceramic green sheet 35.

A laser beam for processing the workpiece is emitted from a laser oscillator 45 of the beam generator 2. As the laser oscillator 45, a conventionally known excimer laser, YAG laser, CO ₂ laser, or the like is used. The laser beam 4 having a wavelength of 355 nm emitted from the laser oscillator 45 is reflected in a predetermined direction by the total reflection mirror 7 and enters the combiner 9.

  The guide laser oscillator 43 emits a guide laser beam having a wavelength in the visible wavelength region that does not have a processing function. The guide laser beam is used to align the laser beam with the workpiece and adjust the processing size.

  Next, the optical system 6 will be described. The optical system 6 includes a plurality of total reflection mirrors 7, 11, 15, 17, 19, a combiner 9, a mask 13, a diffraction element 3 connected by a motor 5 that rotates in the direction of arrow 8, a collimator lens 21, and an x galvano scanner 31. The galvano scanners 47 and 48 included in each of the y galvano scanners 47 and the condenser lens 29, and guides the laser beam 4 to the green sheet 35.

  Next, the support frame 33 will be described. The support frame 33 has an inverted U shape, and includes a pair of legs 79 and 85 extending in the vertical direction and a pair of cross members 81 and 83 extending between the upper ends of the legs 79 and 85 and extending substantially horizontally. Become. The transverse members 81 and 83 are parallel and spaced apart from each other. A galvano box 23 slidable in the direction of arrow 39 (y-axis direction) is mounted between the cross members 81 and 83. On the side surface of the galvano box 23, an image processing camera 25 is disposed that is directed vertically downward to recognize the position of the ceramic green sheet 13.

  Further, an x galvano scanner 31 and a y galvano scanner 47 are arranged in the galvano box 23. The galvano scan mirrors 32 and 48 provided in each scanner regulate the reflection angle to define the irradiation position of the laser beam in the x-axis 75 direction and the y-axis 76 direction on the processing coordinates described later (see FIG. 4). .

  Further, an fθ lens 29 for condensing the laser beam reflected by the galvano scan mirrors 32 and 48 is disposed in the galvano box 23.

  Next, the transport unit 8 will be described. The transport unit 8 includes a pair of rollers 87 and 89 that support the X-axis stage 37 and the continuous reel-shaped ceramic green sheet 35. The continuous reel-shaped ceramic green sheet 35 is conveyed in a direction intersecting with the transverse members 81 and 83 of the support frame 33 (that is, from left to right in FIG. 1). The X-axis stage 37 is configured to be movable in the direction in which the green sheet 35 extends, that is, in the x-axis direction (arrow 41).

  The laser beam irradiation by the laser processing apparatus 1 having the above configuration will be described.

  The processing laser beam emitted from the laser oscillator 45 enters the combiner 9 via the reflection mirror 7. On the other hand, the guide laser beam in the visible light region irradiated from the guide laser oscillator 43 is also incident on the combiner 9. The processing laser beam and the guide laser beam are aligned with each other by the combiner 9.

  Further, the processing laser beam and the guide laser beam that are coaxial with each other by the combiner 9 pass through the opening of the mask 13 via the reflection mirror 11. The laser beam 4 that has passed through the mask 13 is formed into the same shape as the processed shape.

  The shaped laser beam 4 is reflected by the reflection mirrors 15, 17 and 19 and enters the diffraction element 3. The laser beam 4 that has passed through the diffraction element 3 is branched into a plurality of laser beams having the same shape.

  The branched laser beam is converted into a parallel beam by the collimator lens 21. Thereafter, the reflection angle is changed by the x galvano scan mirror 32 and the y galvano scan mirror 48 of the x galvano scanner 31, the y galvano scanner 47, and machining coordinates formed by xy axes 75 and 76 (see FIG. 4) described later. Directed to a predetermined position.

  Further, the laser beam that has passed through the galvano scanners 31 and 47 enters an fθ lens 29 that is a condenser lens. The laser beam split into a plurality of beams by the diffraction element 3 is collected by the fθ lens 29 and irradiated onto the ceramic green sheet 35.

  FIG. 2 is a configuration diagram showing the main elements of the optical system 6 of the above embodiment. On the optical path from the laser oscillator 45 to the ceramic green sheet 35 that is a workpiece, the diffraction element 3 with the mask 13 and the drive motor 5 mounted from the laser light source side, the collimator lens 21, the x galvano scan mirror 32, and the y galvano. The scan mirror 48 and the fθ lens 29 are arranged in this order.

In the optical system 6, the diameter φd of the through hole processed into the ceramic green sheet 35 has the following relationship.
φd = (f2 / f1) × φb

  Here, the distance from the mask 13 to the collimator lens 21 is f1, and the distance from the fθ lens 29 to the green sheet 35 is f2. f2 / f1 is the transfer magnification. This relational expression is limited to the case where the laser beam is split into two by the diffraction grating 3 and transferred.

  Next, control of the laser processing apparatus 1 will be described. FIG. 3 is a block diagram showing a control system of the laser processing apparatus.

  The CPU (control unit) 53 of the laser processing apparatus 1 includes a memory (storage unit) 55 for storing correction values for position correction and the like. As the memory 55, a flash memory, a ROM, or the like can be used.

  The control unit 53 is connected to the laser oscillator 45 and the guide laser oscillator 43 and controls them. Further, the control unit 53 recognizes the positions of the diffraction element rotation control unit 57 for rotating the diffraction element 3, the galvano scanner control unit 59 for controlling the y galvano scan mirror 32 and the y galvano scan mirror 48, and the green sheet 35. Connected to an image processing device 61 for controlling the camera 25, an X-axis stage 37, and a drive system controller 63 for driving the galvano box 23 moving in the y-axis direction (arrow 39).

  A method of forming a through hole in a ceramic green sheet using the laser processing apparatus 1 configured as described above will be described with reference to FIG.

  First, after the reel-shaped ceramic green sheet 35 is placed on the X-axis stage 37, the positioning reference hole 71 provided in the green sheet 35 is recognized by the camera 25, and the processing coordinate and workpiece are recognized by the image processing device 61. The difference from the arrangement coordinates is calculated and stored in the memory 55. Here, the processing coordinates are a two-dimensional plane formed by orthogonal x-axis 75 and y-axis 76 that serve as a reference when the laser beams of x-galvano scan mirror 32 and y-galvano scan mirror 48 of laser processing apparatus 1 are reflected. The work arrangement coordinates are a two-dimensional plane formed by the X axis 77 in the longitudinal direction of the reel-like green sheet and the Y axis 78 orthogonal to the X axis 77.

  A rotation angle obtained by rotating the diffraction element 3 by the motor 5 and a rotation angle of the irradiation position on the processing coordinates generated by the rotation are obtained in advance and stored in the memory 55. In addition, the x-axis 75 and the y-axis 76 of the processing coordinates used as a reference by the x-galvano scanner 31 and the y-galvano scanner 47 and the movement direction (arrow 39 direction) of the X-axis stage 37 in the direction of the arrow 41 and the y-axis. Keep it aligned. Then, the x and y galvano scan mirrors 32, 48, the X axis stage 37, and the galvano box 23 are moved as necessary to set processing coordinates.

  Next, information about the xy axes 75 and 76 and the XY axes 77 and 78 (shift in the x-axis direction, shift in the y-axis direction, shift in the rotation direction, etc.) is input to the CPU 53 and processed. Information for aligning the x-axis and the x-axis and the y-axis and the y-axis based on the calculation result is input to the drive system controller 63 or the galvano scanner controller 59 and the rotating element rotation controller 57. Based on the input information, for example, the xy galvano scan mirrors 32 and 48 are moved, or the X-axis stage 37 and the galvano box 23 are moved. Regarding the rotation direction θ deviation, the diffraction element 3 is rotated by the rotation element rotation control unit 57 to correct the deviation. The calculation result relating to the shift in the rotation direction θ is stored in the memory 55 in advance, and the information on the corresponding rotation amount is obtained by referring to the rotation amount of the rotation element 3 necessary for the shift in the rotation direction θ. Input to the diffraction element rotation control unit 57.

  Then, a laser beam and a guide laser beam are irradiated from the laser oscillator 45 and the guide laser oscillator 45, respectively. The irradiated laser beam is punched at a predetermined position on the green sheet 35 by the optical system 6. In this punching step, the green sheet 35 is repeatedly irradiated by changing the reflection angle of the x galvano scan mirror 32 and the y galvano scan mirror 48.

  Next, the relationship between the processing coordinates and the workpiece placement coordinates will be described.

  FIG. 4 is a schematic diagram of the ceramic green sheet 35 in which the through holes 36 are formed. FIG. 5 is a partially enlarged view of FIG.

  In the drawing, machining coordinates defined by an x-axis 75 and a y-axis 76 orthogonal to the origin o, and workpiece placement coordinates defined by an X-axis 77 and a Y-axis 78 orthogonal to the origin O are shown. The arrival position of the laser beam emitted from the laser processing apparatus 1 is defined on the processing coordinates. That is, the irradiation position of the laser beam is defined as a point on the processing coordinates.

  The workpiece placement coordinates are coordinates defined by the longitudinal direction of the green sheet 35 placed on the X-axis stage 37, that is, the X-axis 77, and the short-side direction, that is, the Y-axis 78. Are orthogonal at the intersection point O.

  Further, the deviation of the rotation direction of the y-axis 76 and the Y-axis 78 or the x-axis 77 and the X-axis 75 with respect to the origin o or O when the machining coordinate origin o and the workpiece placement coordinate origin O coincide with each other is the rotation angle θ. Indicated.

  When the green sheet 35 is supplied to the X-axis stage 37 of the laser processing apparatus 1 in a predetermined manner, the processing coordinates and the workpiece placement coordinates match. Therefore, drilling can be performed without correcting the laser irradiation position.

  However, the green sheet 35 may not be supplied properly, or the green sheet 35 may be displaced on the X-axis stage 37. FIG. 4 shows a state where the supplied green sheet 35 is tilted with respect to the X-axis stage 37 for some reason, and the workpiece placement coordinates and the processing coordinates are shifted. Specifically, the origin O of the workpiece placement coordinates and the origin o of the processing coordinates coincide with each other, but are shifted by the rotation angle θ. In other words, the y-axis 76 of the processing coordinates and the Y-axis 78 of the work placement coordinates are shifted by an angle θ.

  FIG. 5 is a partially enlarged view of FIG. 4 and shows the origins o and O regions of the processing coordinates and the workpiece placement coordinates. The figure shows a state in which there is a deviation of the rotation angle θ between the two coordinates. When the deviation in the angular direction is not corrected, the through hole 38 is drilled along the y-axis direction. Therefore, it is formed at a position shifted by the rotation angle θ from the through hole 38 to be originally formed along the Y axis 78 of the workpiece arrangement coordinate.

  In order to eliminate such an error in the position of the through-hole, correction is performed by rotating the diffraction element by the rotation angle θ. The correction is performed with reference to the midpoint of the line connecting the two through holes 36 to be drilled.

  First, correction is performed so that the origin o of the processing coordinates and the origin O of the work placement coordinates coincide with each other at the midpoint of the line connecting the locations where the through holes are to be formed. This correction is performed by moving the X-axis stage and the galvano box (in the y-axis direction), or by appropriately moving the x-galvano scan mirror 32, the y-galvano scan mirror 48, and the like. Next, with respect to the rotation angle θ, the diffraction element 3 is rotated by an amount corresponding to the rotation angle θ. Since the branch center of the diffraction element 3 and the origin o of the processing coordinates are set in advance, the diffraction element is rotated around the branch center.

Consider a case where the rotation angle θ is not corrected using specific numerical values. When a diffraction element having a branch pitch of 2.5 mm (2500 μm) on the surface of the green sheet is used, if the rotation angle θ is shifted by 1 °,
The through hole 38 is formed at a position of 2500 μm × tan (1 °) ÷ 2≈21 μm and at a position shifted in the x-axis direction of the processing coordinates.

  However, by rotating the diffractive element 3, the shift of the rotation angle θ can be eliminated, and the through hole can be formed with high accuracy.

  In the embodiment described above, the diffractive element 3 divides the laser beam into two and forms two through-holes at the same time. However, the number of the laser beams to be branched can be appropriately changed without being limited to this. Needless to say.

  Furthermore, although the ceramic green sheet is provided with a through hole, it goes without saying that the ceramic green sheet can be applied as an apparatus for forming a through hole in a ceramic green sheet with a carrier film or an electronic component.

  Further, although the front circular through-hole is provided, it is needless to say that the present invention can be applied not only to a circular shape but also to a rectangular shape, and not only to a through-hole but also to groove processing.

  In the present embodiment, an electric motor is used to rotate the diffraction element, but a pulse motor, a servo motor, or the like can be applied as appropriate.

  The present invention can be embodied in many forms without departing from its essential characteristics. Therefore, it is needless to say that the above-described embodiment is exclusively for description and does not limit the present invention.

  The laser processing apparatus and laser processing method according to the present invention can be used for drilling ceramic green sheets, ceramic green sheets with a carrier film, electronic components, and the like.

1 is a basic configuration diagram of a laser processing apparatus 1 according to the present invention. It is a block diagram of the optical system of FIG. It is a block diagram regarding control of the laser processing apparatus of FIG. It is a schematic diagram of the ceramic green sheet 35 in which the through-hole was formed. It is the elements on larger scale of FIG. (A) is a block diagram of the conventional laser processing apparatus, (b) is a figure which shows the processing pattern of the green sheet 135. FIG. (A) is a block diagram of the conventional laser processing apparatus, (b) is a figure which shows the processing pattern of the green sheet 135. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 3 Diffraction element 5 Drive apparatus 21 Collimator 29 f (theta) lens 31, 47 xy galvano scanner 35 Green sheet 45 Laser oscillator

Claims (3)

A laser processing apparatus for drilling a workpiece using a laser beam,
A mask for shaping a laser beam into a predetermined shape on a light path from a laser source to a workpiece, and a diffraction element for branching the laser beam that has passed through the mask into a plurality of beams; The laser processing apparatus according to claim 1, wherein the element is provided with driving means for rotating the diffraction element.   The laser processing apparatus according to claim 1, wherein the workpiece is a continuous reel-shaped member. A laser processing method for drilling a workpiece using a laser beam, and forming a laser beam into a predetermined shape by passing the laser beam through a mask on an optical path from the laser source to the workpiece. A laser processing method, wherein the laser beam is incident on a diffraction element, branched into a plurality of beams, and the irradiation position of the plurality of beams is changed by rotating the diffraction element.

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