JP2014184456A - Laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize laser processing by beam scanning by an inexpensive optical system.SOLUTION: An in-focus surface Z=-Z2 from a condenser lens 26 for condensing a laser beam and a shit amount X=X1 of the condenser lens 26, are set so that optical distortion of a laser beam on a wire 12 when shifting the condenser lens 26 only by a distance Z=-Z2 from a processing object and also a predetermined shift amount X=X1 from an optical axis LX of the laser beam, becomes the substantially same as optical distortion of the laser beam in an in-focus surface Z=-Z1 of becoming a limit distance capable of removing a coating resin from the processing object when a central position of the condenser lens 26 is the optical axis LX. This technology can be applied to a laser processing device.

Description

  The present technology relates to a laser processing apparatus, and more particularly, to a laser processing apparatus capable of performing laser processing while scanning a beam spot with a low-cost optical system.

  As mobile devices are miniaturized and high-density packaging is accompanied by the miniaturization of built-in electronic components, the coating resin (insulating coating) on the conductor (metal) is also thinned and thinned locally. Processing with high quality removal is difficult with conventional methods.

  In the conventional mechanical stripping method, since the conductor is damaged or only the coating resin (insulating coating) cannot be reliably peeled off at a predetermined position, laser processing is promising.

  In laser processing, the coating resin at an arbitrary position can be peeled off by scanning a laser beam spot on the surface (mainly a plane) of a workpiece. As a method of scanning the beam spot of the laser beam, a method using a galvano scanner is generally widely used (see Patent Document 1).

  In the method using the galvano scanner, free scanning can be performed at high speed and accurately over a wide area in conjunction with a computer. This method using a galvano scanner is mainly used for laser markers, laser patterning, and the like.

  Furthermore, as a method of scanning using a galvano scanner while keeping a beam spot having a predetermined converging diameter in an area of a certain range on the XY plane of a workpiece, there are two methods depending on the lens used.

  One is a method that uses an Fθ lens for condensing, and the other is a method that uses a normal spherical lens for condensing and another spherical lens for Z-axis control, and corrects the position of the condensing point. It is.

JP 2012-640 A

  However, when an Nd: YAG (1 μm band) laser, a CO2 (1 μm band) laser, or the like, which is a general industrial laser, is used, the resin peripheral portion or the metal surface may be deteriorated.

  In addition, Nd: YAG (1 μm band) lasers and CO2 (1 μm band) lasers, which are general industrial lasers, have a very high absorption rate for resin materials. Although an ultraviolet laser with less influence is optimal as processing quality, the initial cost and running cost of the light source are too expensive for the added value of the processed parts, so that it is not suitable for this purpose.

  Furthermore, the required laser processing does not require relatively high precision (thermal processing that does not require a sharp processing edge), but for example, it is possible to irradiate several points in a small part of about several millimeters. In this case, the method using the Fθ lens, the galvano scanner, or the like used in Patent Document 1 is an excessive specification and is a high-cost method.

  The laser wavelength suitable for the required laser processing is, for example, around 1.06 μm (Nd: YAG laser, etc.), which is common in industrial applications, and its harmonics (second order, third order, fourth order), 10.6 μm ( If it is a CO2 laser, etc., an Fθ lens designed with that wavelength can be used, and there are many variations of optical specifications.

  However, in the case of an uncommon wavelength, it is necessary to newly design an Fθ lens, resulting in high cost.

  Furthermore, a general spherical lens can be used as long as it uses a normal spherical lens for condensing and another spherical lens for Z-axis control to correct the position of the condensing point. Three-axis control is required, which increases the cost.

  The present invention has been made in view of such circumstances, and in particular, enables laser processing by beam scanning to be realized by a low-cost optical system.

  A laser processing apparatus according to one aspect of the present invention includes a laser light source that generates laser light, a condensing lens that condenses the laser light generated by the laser light source on a processing target, and the condensing lens. The condensing lens is shifted within a plane perpendicular to the optical axis of the laser beam and within a predetermined distance from the workpiece within a range from the optical axis to a predetermined shift amount. A condensing lens driving unit for driving, and the predetermined shift amount is the optical distortion of the laser beam on the object to be processed when the predetermined shift amount is shifted from the optical axis by the predetermined shift amount. Limit for processing the workpiece with the laser light when the lens is closer to the condenser lens than the focal position of the laser light and the center position of the condenser lens is the center of the laser light Distance of Is set so that the optical distortion of the definitive laser light and substantially the same.

  As a result, laser processing for applications in which the allowable range of processing quality required for laser beam focusing accuracy (= irradiation intensity) is relatively wide, and any number near the central axis of the focusing lens In a processing apparatus that performs laser irradiation at the position of a spot, it is possible to realize scanning of a beam spot on a processing target with a low-cost optical system configuration.

  A control unit for controlling the condensing lens driving unit may be further included, and the control unit uses the spot diagram obtained by optical calculation of an optical system using the condensing lens to perform the predetermined operation. And the predetermined shift amount can be set.

  Accordingly, the condenser lens is shifted within a range from the optical axis to the predetermined shift amount within a plane that is a predetermined distance from the workpiece and is orthogonal to the optical axis of the laser beam. By doing so, it becomes possible to scan the laser spot as the processing position, and it is possible to perform processing at a plurality of processing positions without changing the position of the processing object.

  The laser light source can generate laser light having a wavelength longer than 1.9 μm and shorter than 3.0 μm.

  The wavelength of the laser beam has a low absorptance with respect to the first substance having the first melting point and a high absorptance with respect to the second substance having the second thermal decomposition point lower than the first melting point. The absorptivity characteristics for both substances are selected as a wavelength that is relatively large compared to wavelengths outside the range where the wavelength is longer than 1.9 μm and shorter than 3.0 μm. This makes it possible to remove the second substance covering the first substance without damaging the first substance constituting the workpiece.

  The laser light generated by the laser light source may include Er: YAG laser light, Cr, Tm, Ho: YAG laser light, and Tm fiber laser light.

  As a result, it is possible to generate laser light having a wavelength of laser light longer than 1.9 μm and shorter than 3.0 μm, and as a result, the first material can be coated without damaging the first material constituting the workpiece. The second substance can be removed.

  The workpiece may be obtained by adding a second substance having a thermal decomposition point lower than the first melting point on the first substance having the first melting point.

  The object to be processed may be an electric wire in which a first substance containing a metal as a conductor is covered with a second substance made of resin.

  This makes it possible to remove the resinous second substance covering the conductor without damaging the first substance that is the conductor of the electric wire that is the object to be processed.

  The first material including a metal that is the conductor may be a conductor including aluminum, tin plating, and nickel plating, and the second material including the resin includes polyamide, polyurethane, polyester, and phenol resin. Can be.

  As a result, the object to be processed can be an electric wire composed of a first substance that is a conductor and a second substance that is a coating resin that coats the first substance. It is possible to use the first substance by removing the second substance as the coating resin from the first substance as the body.

  The condensing lens driving unit includes a first stage that shifts the condensing lens in a first direction within a plane orthogonal to the optical axis of the laser light, and is not parallel to the first direction. A second stage shifted in the second direction can be included.

  As a result, the laser processing is used for applications where the tolerance of processing quality required for the laser beam focusing accuracy (= irradiation intensity) is wide, and in any number of locations near the central axis of the focusing lens. In the processing of irradiating the position with laser, it is possible to perform processing by scanning the beam spot at an arbitrary position with respect to the processing target.

  The condensing lens driving unit includes a rotation stage that rotates the condensing lens around a position different from the center of the condensing lens in a plane orthogonal to the optical axis of the laser light. Can be.

  As a result, the laser processing is used for applications where the tolerance of processing quality required for the laser beam focusing accuracy (= irradiation intensity) is wide, and in any number of locations near the central axis of the focusing lens. In the processing of irradiating the position with laser, it is possible to perform processing by scanning the beam spot at a position on the circumference centering on a predetermined position with respect to the processing object.

  The condensing lens driving unit includes a rotation stage that rotates by placing the condensing lens in a plane orthogonal to the optical axis of the laser light, a cam that rotates in contact with the rotation stage, and A pressing portion that presses the rotary stage so as to contact the cam can be included.

  Thereby, laser processing for applications in which the allowable range of processing quality required for laser beam condensing accuracy (= irradiation intensity) is wide, and in any number of locations near the central axis of the condensing lens In the process of irradiating the position with laser, it is possible to process the object to be processed by scanning the beam spot at a position set in advance by the shape of the cam.

  In one aspect of the present invention, laser light is generated by a laser light source, the laser light generated by the laser light source is condensed on a workpiece by a condenser lens, and the condenser lens is It is driven within a plane perpendicular to the axis of the laser beam within a predetermined distance from the axis, and the object to be processed is placed on the first substance having the first melting point from the first melting point. A second substance having a lower second melting point is added, and the predetermined distance and the predetermined shift amount are the predetermined distance from the object to be processed, and the predetermined shift amount, and The optical distortion of the laser beam on the workpiece when shifted from the optical axis by the predetermined shift amount is closer to the laser light source than the focal position of the laser beam by the condenser lens, and , The center position of the figure is set to be substantially equal to the optical distortion of the laser beam in the said processing target removable limit distance of the second material than the material by the laser beam when the center of the laser beam.

  According to one aspect of the present invention, laser processing is used for a wide range of allowable processing quality required for laser beam focusing accuracy (= irradiation intensity) and near the central axis of the focusing lens. In the processing of irradiating the laser beam at any of several positions, a beam spot scanning mechanism set at the processing position with respect to the processing target can be realized at low cost.

It is a figure which shows the structural example of one Embodiment of the laser processing apparatus to which this invention is applied. It is a figure explaining operation | movement of the condensing lens drive part of FIG. It is a figure explaining a coma aberration and curvature of field. It is a figure explaining the structure for scanning the conventional beam spot. It is a figure explaining the process which sets the in-focus surface and the shift amount for scanning a beam spot. It is a figure explaining that the cross-sectional shape of a beam spot changes with the scanning of a beam spot. It is a figure explaining that the cross-sectional shape of a beam spot changes with the scanning of a beam spot. It is a flowchart explaining the process which sets the in-focus surface and the shift amount for scanning a beam spot. It is a figure explaining the structural example of 1st Embodiment of a condensing lens drive part. It is a figure explaining the structural example of 2nd Embodiment of a condensing lens drive part. It is a figure explaining the structural example of 3rd Embodiment of a condensing lens drive part. It is a figure explaining the absorption factor for every frequency of the laser beam for every kind of metal used as the material of the core of a wire. It is a figure explaining the absorption band of the infrared light for every kind of resin used as the material of the covering resin of a wire. It is a figure explaining the resin temperature rise and metal temperature rise when each of Nd: YAG laser beam and Er: YAG laser beam is irradiated to the wire. It is a figure which shows the modification of the laser processing apparatus to which this invention is applied.

[Configuration example of laser processing equipment]
FIG. 1 is a diagram showing a configuration example of a laser processing apparatus to which the present invention is applied. The laser processing apparatus 11 of FIG. 1 irradiates a coating resin at a predetermined position by irradiating a predetermined position on a wire 12 (an electric wire having a conductor coated with a resin) 12 as a processing target. The process which peels is given. The wire 12 is, for example, a so-called conductor in which aluminum, copper, iron, tin plating, and nickel plating are used as a core wire, and the periphery thereof is covered with a resin made of, for example, polyamide, polyurethane, polyester, and phenol resin. An electric wire or a signal line. Further, for example, when a plurality of wires are provided in a narrow range, the laser processing apparatus 11 is configured to be driven by shifting the center position of the condenser lens with respect to the optical axis. By shifting the optical lens, the laser spot of the laser beam is scanned, so that the processing resin is peeled off at any necessary positions on the plurality of wires without moving the workpiece. There may be a plurality of wires as the object to be processed as described above, or a single wire as a matter of course.

  The laser processing apparatus 11 includes a guide visible laser light source 21, a laser light source 22, a beam expander 23, a mirror 24, a condensing lens driving unit 25, a condensing lens 26, and a control unit 27.

  The guide visible laser light source 21 generates laser light composed of the visible light for guiding the laser light generated by the laser light source 22, and the beam expander 23 and the mirror 24 in the same manner as the laser light generated by the laser light source 22. And toward the condenser lens 26. Then, the guide laser light generated by the guide visible laser light source 21 is condensed by the condenser lens 26 and irradiated onto the wire 12 that is the object to be processed, thereby confirming the irradiation position.

  The laser light source 22 generates laser light required for processing and emits it toward the beam expander 23. The laser beam generated here is, for example, an Er: YAG laser beam (wavelength: 2.94 μm) that is a solid state laser, or a Cr, Tm, Ho: YAG laser beam (wavelength: 2.08 μm), or a Tm that is a fiber laser. For example, fiber laser light (wavelength: 1.95 μm). The laser light generated by the laser light source 22 is preferably a laser light that removes only the coating resin of the conductor of the wire 12 and does not damage the conductor. For example, the wavelength is 1.9 μm to 3.0 μm. The laser beam is preferably not limited to the above-described laser beam as long as this laser beam is satisfied. Also, what kind of laser light is appropriate as the laser light generated from the laser light source 22 will be described later with reference to FIGS.

  The beam expander 23 expands the laser light generated by the laser light source 22 into a parallel light beam having a predetermined magnification and irradiates the condenser lens 26 via the mirror 24. Note that the magnification of the beam expander 23 is set according to the beam diameter of the laser light generated by the laser light source 22, but may not be necessary depending on the beam diameter generated by the laser light source 22. .

  The condensing lens 26 condenses the parallel light beam incident from the beam expander 23 via the mirror 24 so as to be a beam spot that can be processed on the wire 12 that is a processing target. The condensing lens 26 is shown in FIG. 1 for the case where it is constituted by a single lens. However, the collimated light beam incident from the beam expander 23 via the mirror 24 is converted into a processing object. Any other optical system may be used as long as an optical system capable of focusing so as to form a beam spot that can be processed on the wire 12 is used. For example, a plurality of lenses can be used to collect the entire optical system. A function equivalent to that of the optical lens 26 may be realized.

  The condenser lens 26 is configured to be driven by the condenser lens driving unit 25 within a predetermined shift amount from the optical axis in a plane orthogonal to the optical axis of the laser light. The machining position can be scanned by changing the position of the beam spot by driving. The control unit 27 controls the operation of the condensing lens driving unit 25 and moves on the plane orthogonal to the optical axis direction and the amount of movement of the condensing lens 26 in the Z-axis direction that is the optical axis direction of the laser light. The movement amount in the X-axis direction and the Y-axis direction indicating the coordinate position is controlled. Further, the control unit 27 executes a setting process for setting the movement amount in the Z-axis direction and the limit value of the movement amount in the X-axis direction and the Y-axis direction based on the optical data of the condenser lens 26. Based on the limit value information, the condenser lens driving unit 25 is controlled to drive the condenser lens 26. The movement of the condenser lens 26 in the Z-axis direction is only driven at the time of setting, and when scanning the laser spot at the time of processing, the X-axis direction in the plane orthogonal to the optical axis is used. And only shifting in the Y-axis direction. Further, the moving mechanism of the condenser lens 26 in the Z-axis direction may be omitted if there is a moving mechanism corresponding to the wire 12 for the purpose of adjusting the position in the Z-axis direction, which will be described later with reference to FIG.

  That is, as shown in FIG. 2, the condensing lens driving unit 25 is an object to be processed when the optical axis L of the incident laser light and the center of the condensing lens 26 are coaxial, for example. It is assumed that the center position of the beam spot on a certain wire 12 is the position C1. Here, when the condenser lens 26 (solid line) is moved to the condenser lens 26 ′ (dotted line) by the condenser lens driving unit 25, the trajectory of the laser beam constituting the beam spot center changes, and the beam spot center becomes It changes from position C1 to position C2. Since the machining position changes due to such a change, a plurality of positions can be machined without moving the wire 12 that is the machining object.

  In FIG. 2, the surface that is orthogonal to the optical axis L and at which the wire 12 that is the object to be processed exists is expressed as an XY plane, and the optical axis L of the laser light is The parallel direction (upward in the figure) is expressed as the Z axis. Here, the cross mark at the lower right in the drawing indicates that the back side with respect to the paper surface is the Y-axis direction, and that the X-axis is in the right direction in the drawing.

  In such a configuration, it is desirable that the condenser lens 26 is a lens having a relatively large radius of curvature with respect to the processing range of the wire 12. If the radius of curvature is too small, for example, as shown in the left part of FIG. 3, the condensing lens in a focal plane FP that is a plane perpendicular to the optical axis on the focal length of the condensing lens 26. This is because coma aberration is generated by light incident from a direction that forms a predetermined angle with respect to the central axis of 26. That is, among the light beams L1 to L5 in FIG. 3, the light beam L5 incident at a position far from the central position of the condenser lens 26 indicated by the one-dot chain line is incident at the central position of the condenser lens 26 on the focal plane FP. It is projected to a position separated from the central position by a distance K from the light beam L3. Since coma is unlikely to occur with a lens having a large radius of curvature, it is desirable that the condenser lens 26 has a relatively large radius of curvature.

  Further, as indicated by the dotted line in the right part of FIG. 3, the distance from the condensing lens 26 from the focal plane FP is larger than the curvature of field formed by the positions where the light beams incident from various directions are condensed. The laser spot is set so as to form a laser spot that can be processed on the wire 12 that is an object to be processed on the near in-focus surface IFP. By doing so, the influence of the spread of the focus (blurring) caused by the curvature of field and the influence of the above-mentioned coma aberration are offset, and the intensity of the laser beam can be increased even if the position of the beam spot on the wire 12 changes. It becomes possible not to change.

  In the right part of FIG. 3, the light beams L11 to L16 are incident on the condenser lens 26, and the focal position at the angle from the light beams L11 and L12 shown by solid lines is the focal position F1. The focal position at an angle from the light beams L13 and L14 parallel to each other indicated by a dotted line is the focal position F2, and the focal position at an angle from the light beams L15 and L16 parallel to each other indicated by a dashed line is It is shown that the focus position is F3. In addition, it is shown that the curvature of field occurs because the focal positions F1 to F3 in the light rays from different directions are all curved as indicated by dotted lines. Furthermore, a plane corresponding to the focal position F3 closest to the focal plane FP and parallel to the focal plane FP is shown as an in-focus plane IFP. In addition, a surface that is the same as the distance between the focal plane FP and the in-focus plane IFP and that is on the opposite side of the focal plane FP from the condensing lens 26 with respect to the focal plane FP is referred to as an out-focus plane OFP. It is shown.

  As a result, the condensing lens 26 can be constituted by a relatively inexpensive spherical lens having a large radius of curvature, and is required for the laser spot scanning of the laser processing apparatus capable of scanning the laser spot at the processing position. The cost for the configuration of the optical system can be reduced.

  That is, in order to scan the laser spot at the processing position so far, as shown in the left part of FIG. 4, the laser beam expanded to a predetermined light diameter by the beam expander 31 is controlled by a computer (not shown). The laser spot position was changed by focusing using the Fθ lens 33 while changing the direction with the galvano scanner 32.

  Alternatively, as shown in the right part of FIG. 4, instead of the Fθ lens 33, the spherical lenses 34 and 35 are used as condensing lenses, so that the spherical lens 35 is moved in the direction of the arrow in the drawing, so that the laser The laser spot position was changed by controlling the distance of the light in the Z-axis direction.

  In any configuration, it is possible to control with high accuracy, but it becomes an excessively expensive configuration for a laser processing apparatus with a relatively low required level of accuracy such as removing the coating resin on the wire 12.

  Furthermore, for the Fθ lens 33, the wavelength of the laser beam suitable for laser processing is, for example, around 1.06 μm (Nd: YAG, etc.), which is common in industrial applications, and its harmonics (second order, third order, fourth order). 10.6 μm (CO2), an Fθ lens designed with that wavelength can be used, and variations in optical specifications are abundant, so it is possible to select a relatively low-cost one.

  However, since the wavelength of the laser light generated by the laser light source 22 in FIG. 1 is different from those of these general laser lights, it is necessary to newly design an Fθ lens, which is very expensive. .

  In addition, a general spherical lens can be used as long as it uses a spherical lens 34, 35 as a condensing lens instead of the Fθ lens 33. However, three-axis control is required, which increases the cost. .

  On the other hand, as the condensing lens 26 in the laser processing apparatus 11 of FIG. 1, it is possible to employ a lens having a relatively large radius of curvature that can be manufactured relatively inexpensively as described above. Further, as for the method for driving the condenser lens 26, it is only necessary to drive it so as to shift in the in-focus plane orthogonal to the optical axis of the laser beam, so that the condenser lens is driven by a relatively inexpensive driving method. The unit 25 can be configured.

[Setting the distance between the condenser lens and the workpiece and the shift amount of the condenser lens]
Next, a method for setting the shift amount on the in-focus plane perpendicular to the optical axis with reference to the distance from the condensing lens 26 to the wire 12 as the object to be processed and the center of the condensing lens 26 will be described.

  Here, as shown in the upper part of FIG. 5, the position on the Z-axis where the laser light L transmitted through the condenser lens 26 whose center is set at the same position as the optical axis LX of the laser light L is focused. The focal plane Z = 0. Further, the laser beam L is the limit position where the processing quality necessary for removing the metal coating resin of the wire 12 can be realized, and is orthogonal to the optical axis LX closest to the condenser lens 26 in the Z-axis direction. The surface is an in-focus surface Z = −Z1. Further, the out-focus plane Z = Z1 is a plane perpendicular to the optical axis LX that has the same distance on the Z-axis from the focal plane Z = 0 and is opposite to the in-focus plane on the Z-axis. Shall. In the following description, the in-focus plane Z = −Z1 at which the processing quality is within the allowable range is particularly referred to as the depth of focus.

  Further, as shown in the lower part of FIG. 5, when the center position of the condenser lens 26 is shifted from the optical axis LX of the laser light L by the shift amount X1 or −X1 in the X direction, the laser light L is collected. The position in the Z-axis direction where the allowable range is limited by the beam spot generated by being irradiated is set to the in-focus plane Z = −Z2. That is, the condensing lens 26 indicated by the solid line in the upper part of FIG. 5 has its optical axis LX, for example, as shown in the lower part of FIG. When the center position is shifted by the shift amount X = X1 in the X-axis direction, the laser light L incident on the optical axis LX is condensed as shown by the solid line in the figure, and is condensed as shown by the dotted line. After passing through the lens 26 ', it becomes the optical axis LX1, and the laser spot position changes to the in-focus plane Z = -Z2. As shown in the lower part of FIG. 5, due to the symmetry of the condensing lens 26 with respect to the optical axis LX, the condensing lens 26 is shifted by the shift amount X = −X1 to become the condensing lens 26 ″. The optical axis LX changes to the optical axis LX2.

  That is, assuming that the lens is configured as a spherical lens, an optical distortion occurs in the shape of the laser spot corresponding to the magnitude of the shift amount X1 due to the curvature of field corresponding to the radius of curvature of the lens. Here, the optical distortion is distortion caused by the aberration of the condenser lens 26. For example, as shown in the left part of FIG. 6, when the central position of the condenser lens 26 is the same position as the optical axis LX, the object to be processed is shown in the central part of FIG. On the in-focus plane Z where the wire 12 is assumed to exist, a laser spot SP1 having a shape close to a perfect circle is formed. On the other hand, when the center position of the condenser lens 26 is shifted from the optical axis LX by a predetermined shift amount, the optical axis changes to the optical axis LX1 as shown in the lower part of FIG. A laser spot SP2 is configured as indicated by the section. Thus, the substantially perfect laser spot SP1 is changed into a shape like the laser spot SP2 due to optical distortion.

  The processing quality required to remove the metal coating resin of the wire 12 by the laser light L is lowered according to the optical distortion and the size of the laser spot. Therefore, the distance between the condenser lens 26 and the wire 12 that is the object to be processed can be set based on the depth of focus that can maintain the processing quality based on the laser spot and the shift amount.

  A spot diagram is used to evaluate the size and shape distortion of such a laser spot. A spot diagram shows the coordinate distribution of passing light rays on an evaluation surface by tracing a large number of light rays from a point light source to a condenser lens. That is, in the case of the spot diagram of the condensing lens 26, it is a distribution indicating the optical distortion aberration of the optically condensed laser light, for example, as shown in FIG.

  Each of the three spot diagrams in the upper part of FIG. 7 has a shift amount X = 0, and each of the three in the Z-axis direction from the left when the in-focus surface Z = −Z1 is set as the evaluation surface in the Z-axis direction. And when the focal plane Z = 0 is used as the evaluation plane, and when the out-focus plane Z = Z1 is used as the evaluation plane in the Z-axis direction. In the three spot diagrams in the lower part of FIG. 7, the in-focus plane Z = Z2 when the shift amount X = −X1 in the X-axis direction is used as the evaluation plane from the left, and the shift amount X = 0 in the X-axis direction. The evaluation surface is the in-focus surface Z = Z2 when the shift amount X = X1 in the X-axis direction. In each spot diagram, the spot diameter indicated by eight points on the circumference and one point at the center is a laser spot represented by the spot diagram. It is shown that the processing quality deteriorates as the area of the laser spot shape increases and the distortion of the shape increases.

  Here, the spot diagram of FIG. 7 is an example in which laser light is condensed by a single lens having a wavelength of 2.94 μm, a diameter of 2 mm, and a focal length (distance from the condenser lens 26 to the focal plane Z = 0) of 50 mm. In this example, Z1 = 0.2 mm, Z2 = 0.1 mm, and X1 = 1 mm.

  That is, for example, when the laser spot diameter on the in-focus plane Z = −Z1 shown in the upper left of FIG. 7 satisfies the minimum processing quality, from the three spot diagrams shown in the lower stage of FIG. Since the laser spot is smaller than that in the upper left in-focus plane Z = −Z1, it can be considered that the processing quality is satisfied.

  Therefore, using the spot diagram, the in-focus plane Z = −Z1 that guarantees the minimum processing quality is obtained from the focal plane Z = 0, and the laser spot is distorted to a level corresponding to the laser spot at this time. By setting the range of the shift amount X = X1 and the in-focus plane Z = −Z2 at this time, the processing range can be set. That is, even if a different machining position is set as long as it is within the machining range up to the shift amount X = X1 with the optical axis as the center on the in-focus plane Z = −Z2, By moving the condenser lens 26 without moving the wire 12, which is an object, it is possible to change the processing position and process a plurality of processing positions.

[Setting process]
Therefore, the setting process for the in-focus plane Z = −Z2 and the shift amount X = X1 described above will be described. Here, the control unit 27 calculates a spot diagram based on the lens data of the condenser lens 26 and executes a setting process based on the calculation result. A configuration may be executed by generating a diagram.

  In step S1, the control unit 27 calculates a spot diagram based on the lens data, and calculates an in-focus plane Z = −Z1 at the shift amount X = 0 based on the calculation result. That is, the control unit 27 calculates the spot diagram while changing the value in the Z-axis direction, and is the in-focus surface Z farthest from the focal plane Z = 0 and guarantees the processing quality from the condenser lens 26 to the minimum. = -Z1 spot diagram is stored.

  In step S2, the control unit 27 calculates a spot diagram while changing the shift amount X and the in-focus surface Z based on the lens data, and based on the calculation result, the spot diagram of the in-focus surface Z = −Z1. The shift amount X = X1 at which the beam spots based on the same are obtained, and the in-focus plane Z = Z2 at this time is obtained.

  Through the above processing, the control unit 27 controls the condensing lens driving unit 25 to obtain the condensing lens 26 on the in-focus plane Z = −Z2 from the optical axis LX to the central position of the condensing lens 26. Is driven in a range up to X = X1. As a result, within the range in which the condensing lens 26 can be driven by the condensing lens driving unit 25, the wire 12 that is the object to be processed is disposed within the range in which the laser beam can be irradiated. It is possible to machine a plurality of machining locations with a predetermined machining quality without moving the wire 12, which is an object. At this time, there may be a plurality of wires 12 that are the object to be processed, which may be the same processing position or different processing positions.

[Configuration Example of First Embodiment of Condensing Lens Driving Unit]
Next, a configuration example of the first embodiment of the condenser lens drive unit 25 will be described with reference to the block diagram of FIG.

  The condensing lens driving unit 25 in FIG. 9 supports the condensing lens 26, and supports a stage 41 that expands and contracts in the left-right direction in the drawing within a plane orthogonal to the laser light L, and the stage 41. A stage 42 that expands and contracts in the vertical direction is provided. The stages 41 and 42 drive the condenser lens 26 by expanding and contracting in directions orthogonal to each other in a plane orthogonal to the laser light L.

  The stages 41 and 42 are driven by a stepping motor, a servo motor, a voice coil motor, or the like (not shown), and the control unit 27 functions as a motor controller to control the position.

  With such a configuration, the condenser lens 26 can be shifted to an arbitrary position within the in-focus surface Z = −Z2, and as a result, the in-focus surface Z = −Z2 and the shift amount X = X1 can be shifted. Within this range, it is possible to perform processing at an arbitrary processing position. The driving directions of the stages 41 and 42 may be moved to any position within the in-focus plane Z = −Z2 and do not necessarily have to be orthogonal unless they are in the same direction.

[Configuration Example of Second Embodiment of Condensing Lens Driving Unit]
Next, a configuration example of the second embodiment of the condenser lens driving unit 25 will be described with reference to the block diagram of FIG.

  The condensing lens driving unit 25 in FIG. 9 has been described with respect to a configuration example that can be set at an arbitrary position in a two-dimensional plane orthogonal to the optical axis of the laser light. In the case where it is limited to the circumference, the condenser lens 26 may be driven to rotate around a position different from the center of the condenser lens 26.

  That is, the condensing lens driving unit 25 shown in FIG. 10 is rotated by a motor (not shown), on a disc-shaped rotating stage 51 that transmits laser light, and at a predetermined position of the condensing lens 26 at the center of the rotating stage 51. The position is fixed, and as shown by the arrows in the figure, it is rotated and moved in the order shown by the condenser lenses 26, 26 ', 26 ". At this time, the rotary stage 51 is driven. The position of the condensing lens 26 fixed at the center position is set according to the machining position and the shift amount X = X1 obtained by the setting process described above. , A stepping motor, a servo motor, a voice coil motor, or the like, and the control unit 27 functions as a motor controller to control the position.

  With such a configuration, the condensing lens 26 can be shifted to a position on a predetermined circumference within the in-focus surface Z = −Z2, and as a result, the in-focus surface Z = −Z2 and the shift amount X = Processing can be performed at an arbitrary processing position on a predetermined circumference within a range that can be shifted by X1.

[Configuration Example of Third Embodiment of Condensing Lens Driving Unit]
Next, a configuration example of the third embodiment of the condenser lens driving unit 25 will be described with reference to the block diagram of FIG.

  The condensing lens driving unit 25 in FIG. 10 has been described with respect to a configuration example in which the condensing lens 26 can be driven to an arbitrary position on the circumference configured when rotated by the rotary stage 51. For example, when the processing position is not on a specific circumference, the rotating stage on which the condenser lens 26 is placed is tensioned from a predetermined direction, brought into contact with the cam, and the cam is rotated to collect light. The lens 26 may be driven.

  That is, the condensing lens drive unit 25 in FIG. 11 is arranged so that the side surface portion of the transparent rotating stage 64 on which the condensing lens 26 is placed coaxially contacts the side surface of the cam 61 rotated by a motor (not shown). When the springs 62-1, 62-2, and 63 apply tension in the right direction in the figure, the position where the cam 61 abuts against the side surface of the rotary stage 64 changes as the motor (not shown) rotates. Thus, the condenser lens 26 is driven according to the cross-sectional shape of the cam 61. Note that the cross-sectional shape of the cam 61 is set so that the laser spot condensed by the condenser lens 26 on the rotary stage 64 driven by contact passes through the processing position. The motor for rotating the cam 61 is a stepping motor, a servo motor, a voice coil motor, or the like. The control unit 27 functions as a motor controller, and the position is controlled.

  With such a configuration, the condensing lens 26 can be shifted to a predetermined position on the trajectory specified by the shape of the cam 61 in the in-focus surface Z = −Z2, and as a result, the in-focus surface Z = −. It is possible to perform machining at an arbitrary machining position on the track specified by the shape of the cam 61 within a range that can be shifted by Z2 and the shift amount X = X1.

[Laser light generated by laser light source]
Next, laser light generated by the laser light source 22 will be described.

  The laser processing apparatus 11 in FIG. 1 performs a processing process to remove the coating resin on the wire 12 that is a processing target without damaging the core wire made of the conductor. Accordingly, it is essential that the conditions required for the laser beam be such that the coating resin can be removed reliably and the core wire is not damaged.

  The mechanism of the removal process of the coating resin with laser light is as follows. That is, when a laser beam having a predetermined frequency is irradiated, the coating resin resonates with the vibration of the molecular bond of the organic compound, energy absorption occurs, and a temperature increase associated therewith occurs. Eventually, when the melting point and boiling point are reached by this heat, the coating resin is instantaneously vaporized or sublimated and decomposed, so that it is removed as a result. The temperature at which this coating resin is instantaneously vaporized or sublimated and decomposed is generally called a thermal decomposition point and also called ablation.

  Here, in the coating resin having high hygroscopicity, an effect useful for evaporating the resin structure itself is produced by evaporation of the contained water and volume expansion, so that the removal becomes easier. Further, in order to completely remove the coating resin that is an insulating film and expose the surface of the conductor, irradiation energy of a certain amount or more is required, but it exceeds the processing threshold of the metal that is the conductor, that is, the metal If a temperature rise exceeding the melting point of the conductor is generated, the conductor surface is deteriorated.

  Therefore, the laser beam that can reliably remove the coating resin without deteriorating the conductor that is the core wire needs to be a laser beam that can remove the coating resin with an irradiation energy that does not exceed the processing threshold of the metal that is the conductor. There is.

  The conductor constituting the core of the wire 12 is generally copper, aluminum, iron, tin plating, nickel, or the like. Therefore, it is necessary to select a laser beam having a wavelength that is difficult to be absorbed by the conductor constituting these core wires as a laser beam that does not exceed these processing thresholds.

  FIG. 12 shows the absorption rate of laser light on the non-oxidized surfaces of aluminum, copper, iron, nickel, and tin, which are the main conductors constituting the core of the wire 12, about 1 μm, about 1.6 μm, about 2.4 μm, The summary is about 3 to 5 μm and about 8 to 14 μm.

  From these facts, it is clear that the metal constituting the main conductor constituting the core wire has a lower absorptance (increased reflectivity) as the laser light has a longer wavelength. In particular, in these representative metals, it is clear that the absorptance of laser light having a wavelength of about 1 μm is 1 / 2.5 to 1 / 1.5 compared to the absorptance of laser light having a wavelength of about 3.0 μm. It is.

  On the other hand, FIG. 13 shows the absorption position and intensity of the infrared absorption spectrum for amide groups, amino groups, and hydroxyl groups contained in polyamide, polyurethane, polyester, and other phenol resins, which are the main components constituting the coating resin of the wire 12. It is a summary.

The absorption position corresponds to the wavelength, for example, 3550 cm ^-1 corresponds to a wavelength of 2.81 μm, 3400 cm ^-1 corresponds to a wavelength of 2.94 μm, and 3030 cm ^{− 1} corresponds to a wavelength of 3.30 μm. In addition, v in the intensity indicates variable, s indicates strong, and m indicates medium.

  That is, it can be seen that the coating resin of the wire 12 is easily absorbed by the laser light having a wavelength of about 2.8 μm to 3.0 μm.

  For these reasons, the laser beam for processing the wire 12 is unsuitable for a band having a relatively low resin absorptivity, a high conductor absorptivity, and a wavelength shorter than about 1.0 μm. It is considered that one having a wavelength of about 3.0 μm from a range close to 2.8 μm where the absorption rate to the resin is relatively high and the absorption rate of the conductor is low is appropriate. In addition, light absorption due to stretching vibration of molecular bond of resin material is also present in the vicinity of 1.7 μm or more, and compared with laser light having a shorter wavelength than near 1.0 μm, the absorption rate of coating resin and conductor is In some cases, the effect of machining characteristics using the difference can be obtained.

  Therefore, the laser light source 22 of FIG. 1 is configured to generate laser light having a wavelength of about 1.9 μm to 3.0 μm. For this reason, the laser light source 22 includes, for example, Er: YAG laser light (wavelength: 2.94 μm), Cr, Tm, Ho: YAG laser light (wavelength: 2.08 μm or 2.01 μm, etc.), and Tm fiber laser light (wavelength: 1.95 μm) can be used.

  Further, the laser light source 22 is configured to generate pulsed laser light in order to suppress deterioration in processing quality due to excessive heat effects.

  The laser light generated by such a laser light source 22 has low energy required for processing itself and strong absorption by the coating resin layer, so that there is little residual light reaching the conductor. For this reason, for example, it is possible to make it difficult to cause deterioration of the surface of the conductor because the absorption rate into the metal is lower than that of a short wavelength laser beam such as an Nd: YAG laser (wavelength: 1.064 μm). .

  In FIG. 14, Nd: YAG laser (wavelength: 1.064 μm) and Er: YAG laser light (wavelength: 2.94 μm) are used as the laser light source 22, the core of the wire 12 is copper, and the coating resin is This is a polyimide with a thickness of 0.1 mm. The relationship between the irradiation pulse energy, the resin temperature rise, and the metal temperature rise when a laser beam with a beam spot diameter of 0.3 mm and a pulse width of 100 μm is pulsed is calculated. As a result. Here, the left part of FIG. 14 shows the relationship of the Nd: YAG laser (wavelength: 1.064 μm), and the right part of FIG. 14 shows the relationship of the Er: YAG laser light (wavelength: 2.94 μm). Is. The solid line indicates the polyimide surface temperature, the dotted line indicates the polyimide bottom temperature, the alternate long and short dash line indicates the copper surface temperature, and the bold line indicates the copper melting point temperature.

  Polyimide begins to thermally decompose at about 500 ° C., and is carbonized and sublimated at about 800 ° C. or higher, and is removed by laser. In the case of an Nd: YAG laser (wavelength: 1.064 μm), processing starts with about 100 mJ as a threshold value. At this time, although the melting point of the copper surface has not reached 1350 ° C., the energy for starting the processing of copper is reached in spite of the necessity of more energy input to completely remove the resin.

  Also, this calculation assumes a laser with a perfectly uniform intensity distribution, but the actual laser beam has an intensity distribution and has several times the intensity difference, so that the copper surface is not degraded. It is difficult to completely remove only the resin.

  On the other hand, in the case of Er: YAG laser light (wavelength: 2.94 μm), since the resin absorptivity is low, it is removed with lower energy, but there is sufficient margin until copper reaches the melting point due to residual light, Only the resin can be completely removed without copper deterioration.

[Modification of laser processing equipment]
In the above, the configuration example in which the laser beam is irradiated from one direction to the wire 12 has been described. For example, as shown in FIG. 15, the laser beam is irradiated from two directions facing the wire 12. Such a configuration may be adopted.

  In the laser processing apparatus 11 of FIG. 15, for the configuration having the same function as the laser processing apparatus 11 of FIG. 1, the same name and the same reference numeral (“−” are added) (It is a code | symbol which shows that it is the structure provided with the same function, but the description shall be abbreviate | omitted). The laser processing apparatus 11 of FIG. 15 differs from the laser processing apparatus 11 of FIG. 1 only in that a half mirror 111 for splitting laser light is provided, and the other configurations are the same. The description is omitted.

  With the configuration as described above, according to the laser processing apparatus of FIG. 1, in the removal processing of the coating resin (insulating coating) on the metal conductor, the deterioration of the surface of the conductor is suppressed, and the coating resin (insulating coating) ) Can be completely removed.

  Moreover, since the irradiation energy required for processing can be kept low, the output of the laser light source can be reduced, and downsizing, cost reduction, and low power consumption can be realized.

  In addition, an expensive optical system (for example, a homogenizer, optical fiber, etc.) is required for high-precision energy control and uniform irradiation intensity distribution required for selective processing of composite materials. Since it is not configured, low cost can be realized.

  In addition, since there is no deterioration such as discoloration or scoring of the surface of the conductor, the strength of the joint surface when joining with another conductor after removing the coating resin (for example, soldering or laser welding). It is possible to reduce defects and poor electrical contacts.

  Furthermore, in the above description, the example in which the object to be processed is the wire 12 has been described. However, if the above-described conductor is coated with the above-described coating resin, the object other than the wire 12 is processed. You may make it a thing.

  In addition, each step demonstrated with the above-mentioned flowchart can be shared and performed with several apparatuses other than performing with one apparatus.

  In addition, when a plurality of processes are included in one step, the plurality of processes included in the one step can be executed by being shared by a plurality of apparatuses in addition to being executed by one apparatus.

  DESCRIPTION OF SYMBOLS 11 Laser processing apparatus, 12 wire, 21 Guide visible light laser light source, 22 Laser light source, 23 Beam expander, 24, 24-1 to 24-3 Mirror, 25, 25-1, 25-2 Condensing lens drive part , 26, 26-1, 26-2 condenser lens, 27 control unit, 41, 42 stage, 51 rotating stage, 61 cam, 111 half mirror

Claims (10)

A laser light source for generating laser light;
A condensing lens that condenses the laser light generated by the laser light source on the workpiece;
Condensing the condensing lens within a plane perpendicular to the optical axis of the laser light and within a predetermined distance from the workpiece within a range from the optical axis to a predetermined shift amount. A condensing lens driving unit that drives the lens to shift,
The predetermined shift amount is such that the optical distortion of the laser light on the object to be processed when shifted from the optical axis by the predetermined shift amount is less than the focal position of the laser light by the condenser lens. Nearly the same as the optical distortion of the laser beam at a limit distance that allows processing of the object to be processed by the laser beam at a position close to the optical lens and the center position of the condenser lens is the center of the laser beam. Laser processing equipment set to be A control unit for controlling the condenser lens driving unit;
The laser processing apparatus according to claim 1, wherein the control unit sets the predetermined distance and the predetermined shift amount using a spot diagram obtained by optical calculation of an optical system using the condenser lens. The laser processing apparatus according to claim 1, wherein the laser light source generates laser light having a wavelength longer than 1.9 μm and shorter than 3.0 μm. The laser processing apparatus according to claim 3, wherein the laser light generated by the laser light source includes Er: YAG laser light, Cr, Tm, Ho: YAG laser light, and Tm fiber laser light. The laser processing apparatus according to claim 1, wherein the object to be processed is obtained by adding a second substance having a thermal decomposition point lower than the first melting point on the first substance having the first melting point. The laser processing apparatus according to claim 5, wherein the object to be processed is an electric wire in which a first substance containing a metal as a conductor is covered with a second substance made of resin. The first substance containing a metal that is a conductor is a conductor containing aluminum, tin plating, and nickel plating,
The laser processing apparatus according to claim 6, wherein the second substance made of the resin includes polyamide, polyurethane, polyester, and phenol resin. The condenser lens driving unit is
A first stage that shifts the condenser lens in a first direction within a plane orthogonal to the optical axis of the laser beam;
The laser processing apparatus according to claim 1, further comprising: a second stage that shifts in a second direction that is not parallel to the first direction. The condenser lens driving unit is
The laser processing apparatus according to claim 1, further comprising a rotation stage that rotates the condensing lens around a position different from the center of the condensing lens in a plane orthogonal to the optical axis of the laser light. The condenser lens driving unit is
A rotating stage on which the condenser lens is mounted and rotated in a plane perpendicular to the optical axis of the laser beam;
A cam rotating in contact with the rotary stage;
The laser processing apparatus according to claim 1, further comprising: a pressing unit that presses the rotary stage so as to contact the cam.

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