JP5873978B2 - Laser processing method and nozzle manufacturing method - Google Patents

Description

The present invention relates to a processing method using a laser and a method for manufacturing a nozzle by the processing method .

  Conventionally, when a coating liquid such as a phosphor paste is applied to an object to be coated such as a display panel, a method of using a nozzle and discharging the coating liquid from a hole in the nozzle has been used (for example, Patent Document 1). reference).

  However, thousands or tens of thousands of display panels are manufactured per day. Further, since the display is further miniaturized, the distance at which the coating head is scanned with respect to one panel is also increased. It is getting longer.

  For this reason, there is a high possibility that the nozzle used for coating will deteriorate over time, and a nozzle that does not easily deteriorate over time is required.

  However, if a material with high hardness is used to form a nozzle that is unlikely to deteriorate with time, it is difficult to form a hole in the nozzle with high accuracy.

  As a method for processing a nozzle hole, for example, there are a hole processing using a drill and a hole processing using a laser. In general, it is said that drilling using a laser can drill a material having higher hardness than drilling using a drill.

  Conventional hole drilling methods using lasers can be broadly classified into heat processing and direct decomposition or evaporation processing called ablation. Lasers generally used in thermal processing are continuous or pulsed carbon dioxide lasers and infrared lasers such as continuous or pulsed YAG lasers. Lasers used for ablation processing are lasers having a very short pulse width, and excimer lasers and picosecond lasers are known.

  As a technique for processing a precise hole using a laser, for example, there is a method of processing by an ablation process using a pulse laser from the center of the hole toward the outside, and finally a peripheral process for determining the hole shape (for example, , See Patent Document 2).

  FIG. 11 is a diagram showing a conventional laser drilling method. The hole machining method shown in FIG. 11 is a method in which a through hole is laser-processed on a workpiece for machining an inkjet nozzle, and the outer circumferential line 930 is substantially formed inside the outer circumferential line 930 of a desired opening. In order not to process at first, the process of first irradiating the surface of the workpiece with a laser beam at one ablation start point 910 sufficiently separated from the outer circumferential line 930 and the outer circumferential line 930 were controlled not to be deformed. Forming an aperture by driving the laser beam at a variable speed in the direction of the outer circumference 930 and machining the material of the workpiece with a laser drive pattern 920 designed to substantially remove the material in the outer circumference 930. It is a method including the process to do. According to this method, it is said that it is possible to prevent defects such as chipping on the outer periphery of the hole exit surface 900 and perform precise hole processing. The laser intensity in this case is about 50 mJ / mm 2 in order to maintain the surface roughness of the processed surface.

JP 2002-192043 A JP 2005-53362 A

However, before drilling method according to predicate the conventional laser, when performing the high drilling aspect ratio (ratio of the depth of the diameter and the holes of the hole), defects such as chipping of the outer periphery to the bore outlet occurs, The target hole shape cannot be machined. For this reason, the processing yield deteriorates. For example, when a hole having a diameter of 100 μm (aspect ratio: 4) is formed in a SUS430 plate having a thickness of 400 μm, a defect such as a chip occurs on the outer periphery of the hole, and a target hole shape cannot be obtained .

In order to achieve the above object, the laser processing method of the present invention performs an adjustment to increase the laser intensity until the concave portion is not observed when the concave portion is observed on the inner wall of the hole in the test processing performed in advance. A hole is formed in a workpiece using a laser having an adjusted laser intensity of 640 mJ / mm 2 or more .

The manufacturing method of Bruno nozzle of the present invention, the a processing object is a nozzle, characterized in that the production of the nozzle using a laser processing method described above.

As described above, according to the present invention, even when hole processing with a high aspect ratio (ratio of hole diameter to hole depth) is performed, there is a possibility that a defect such as an outer chip is generated at the hole outlet. There is an effect that it is possible to reduce and process the desired hole shape .

Schematic which shows the coating device to the display panel in Embodiment 1 of this invention. The figure which shows the outline of the top view (a) and sectional drawing (b) of the hole of the nozzle used for Embodiment 1 of this invention. Explanatory drawing of the laser processing system of the nozzle used for Embodiment 1 of the present invention Explanatory drawing of progress of hole processing by laser processing system of nozzle of FIG. Explanatory drawing which shows defect example (a), (b) of hole processing of nozzle The figure which shows the explanatory photograph which shows the defect example (a) and (b) of the hole processing of a nozzle The figure which shows the photograph which cleaved and observed the hole inner surface of the nozzle Explanatory drawing of small holes generated on the inner surface of the hole due to melting phenomenon Flowchart of nozzle laser drilling method in Embodiment 1 of the present invention Flowchart of nozzle laser drilling method in Embodiment 2 of the present invention Explanatory drawing showing the conventional laser drilling method

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, and description thereof is omitted as appropriate.

(Embodiment 1)
FIG. 1 is a schematic view showing a coating device for a display panel in Embodiment 1 of the present invention. In the first embodiment, the case where the display panel to be coated is a plasma display panel will be described. However, the present invention can be applied to other display panels by appropriately changing the conditions.

  In FIG. 1, a coating apparatus 1 for a display panel 4 includes a moving table 2 that can reciprocate in the y direction in the figure, a head base 3 that can reciprocate in the x direction in the figure, and the like.

  In the coating apparatus 1, the moving table 2, the display panel 4 placed on the moving table 2, and the head base 3 relatively move in the xy direction. A nozzle unit 5 is mounted on the head base 3 so that a phosphor paste of the order of several tens of μm based on two-dimensional coordinates can be applied to the display panel 4.

  The operations of the moving table 2, the head base 3, and the nozzle unit 5 are controlled by a control unit (not shown). The control unit drives a pump (not shown) that pressurizes the paste holder (coating tank) 7 attached to the tank holder 6 based on a control program stored in the storage unit (not shown). Is also controlled to execute the process of applying the phosphor paste.

  Further, the height of the head base 3 can be adjusted in the z direction in the figure, and the nozzle unit 5 is connected to a paste holder 7 for each of R, G, and B phosphor pastes.

  Holes shown in FIGS. 2A and 2B are formed in the nozzle portion of the nozzle unit 5 shown in FIG. 2A is a view of a part of the nozzle portion of the nozzle unit 5 as viewed from the z-axis direction of FIG. 1, and FIG. It is sectional drawing of xz plane. As shown in FIGS. 2A and 2B, the nozzle unit 5 of the first embodiment has a plurality of holes 8 formed in the nozzle portion, and discharges phosphor paste from the holes 8. It is. As shown in FIG. 2B, the hole 8 of the nozzle unit 5 according to the first embodiment has a tapered shape on the unit surface 5a on the side irradiated with the laser serving as the phosphor paste supply side. Further, the hole 8 of the nozzle unit 5 has a straight shape with no taper or the like on the unit back surface 5b on the phosphor paste discharge side.

  The hole 8 of the nozzle unit 5 according to the first embodiment is circular when viewed from the z-axis direction. As this shape, an elliptical shape or a long hole shape (in a rectangular shape) is used. It is also possible to use a shape with two semicircles.

  Next, a method for forming the hole 8 in the nozzle portion of the nozzle unit 5 will be described.

  FIG. 3 shows a configuration of a laser processing system 101 capable of performing laser processing on a coating nozzle by a laser hole processing method in the first embodiment of the present invention. The nozzle laser processing system 101 includes a laser generator 105 that outputs pulsed laser light, a laser control device (not shown) that controls the laser generator 105, an optical system 106 that includes a lens and the like to be described later, An optical system control device (not shown) for controlling the optical system 106.

  The optical system 106 includes a first mirror 104 that reflects the pulse laser beam 107 output from the laser generator 105, a shutter 110, an attenuator 115, a second mirror 108, a beam expander 120, and a wave plate 125. The scanning mirror 130 and the telecentric lens 140 are provided.

  At the final end of the pulse laser beam 107, a nozzle portion of the nozzle unit 5 which is the workpiece 155 is installed. The attenuator 115 includes a phase plate and a polarizing plate, and is used to adjust the intensity of the pulse laser beam 107.

  Part of the pulse laser beam 107 output from the laser generator 105 is reflected by the first mirror 104. The pulse laser beam 107 reflected by the first mirror 104 passes through the attenuator 115 after passing through the shutter 110. The pulsed laser beam 107 that has passed through the attenuator 115 is reflected by the second mirror 108, is magnified by an appropriate magnification by the beam expander 120, and becomes collimated light. Then, the pulse laser beam 107 that has become collimated light passes through the wave plate 125 for adjusting the polarization direction, is reflected by the scan mirror 130, is condensed by the telecentric lens 140, and reaches the workpiece 155. . Then, the workpiece 155 is processed by the focused beam. Here, when the machining is performed while the scan mirror 130 is swung, the position where the beam reaches the workpiece 155 changes. Therefore, the surface of the workpiece 155 can be scraped off in layers, and can be processed into an arbitrary three-dimensional shape.

  FIG. 4 shows a case in which a through hole having a diameter of 100 μm is formed in a nozzle portion of a nozzle unit 5 using SUS430 (ferritic stainless steel) having a plate thickness of 400 μm, which is a workpiece 155, using a laser processing system 101 for a nozzle. The processing progress at the time of cutting is shown by being cleaved by a plane including the hole center axis. The laser output from the laser generator 105 shown in FIG. 3 was a picosecond laser having a wavelength of 1053 nm, a pulse width of about 20 ps, and a repetition frequency of 2 kHz. The telecentric lens 140 has a focal length of 200 mm, and the focal position is set on the surface of the workpiece. In FIG. 4, reference numeral 202 denotes a workpiece surface, 204 denotes a laser incident direction, 205 denotes a workpiece bottom surface, 210 denotes a hole shape to be originally processed, and 215 denotes a processing surface at a predetermined time during processing.

  Here, as an experiment, the workpiece 155 is moved by drawing the vortex at a speed of about 400 μm / s by moving the pulse laser beam 107 incident on the workpiece surface 202 by swinging the scan mirror 130. Ablation processing was performed in layers. By repeating this a plurality of times, for example, 10 times, 2000 holes were drilled by the method of obtaining the hole shape 210.

  As a result, a hole exit defect as shown in FIGS. 5A and 5B occurred in 50% of the through holes. FIG. 5A is a sectional view of a chip generated on the outer periphery of the nozzle hole, and reference numeral 305 indicates a chip generated on the outer periphery of the hole outlet. FIG. 5B is a cross-sectional view of a defect called a satellite generated near the hole exit. A satellite is a hole that is processed close to the original processing shape on the hole exit side, and the diameter of the satellite is about 1/10 of the diameter of the original processing shape. In FIG. 5B, reference numeral 306 denotes a satellite. When the inner surface of the hole of the satellite 306 was observed, it was found that a recess (horizontal hole) 307 was generated on the inner wall of the hole and penetrated from there to the hole outlet.

  FIG. 6A is a photograph of FIG. 5A observed from the hole outlet side, and FIG. 6B is a photograph of FIG. 5B observed from the hole outlet side. In the processing method for moving the vortex as described above, the target hole shape 210 cannot be obtained due to the occurrence of such a defect.

  Here, the generation mechanism of cracks and satellites around the hole is considered. Conventionally, it is considered that chipping occurs at the moment when a hole penetrates, and it is considered that the generation of chipping can be suppressed by penetrating from the vicinity of the hole center, not from the outer periphery of the hole. However, when drilling a hole with a high aspect ratio, which is the object to be machined this time, as shown in FIG. 5 (b), not only the hole outer periphery but also the nozzle hole outer periphery on the laser exit side of the nozzle hole. It has been found that a hole called a satellite having a diameter of about 1/10 may be processed in the vicinity of the chip and the original processed shape.

  The cause of this satellite is when the laser that has passed through the hole is reflected by the stage after passing through the hole, or when the laser branches due to the back reflection of the reflecting mirror on the optical path, etc. The reason is considered. However, the former is excluded because satellites are generated even when the stage is sufficiently away from the back surface of the workpiece, and the latter is excluded because the probability of satellite generation is as low as about 10% depending on processing conditions.

  FIG. 7 shows the inner wall of the hole by cleaving a hole machined under conditions where the outer circumference of the hole and the satellite are generated in a plane perpendicular to the workpiece surface 202 in order to investigate the cause of the occurrence of the outer circumference of the nozzle hole and the satellite. Is observed. In FIG. 7, reference numeral 501 denotes a laser entrance side, 502 denotes a laser exit side, and 307 denotes a recess (lateral hole) formed in the inner wall of the hole. The generation of the chip 305 and the satellite 306 on the outer periphery of the hole is considered to be caused by the concave portion 307 formed on the inner wall of the hole.

  The concave portion 307 formed on the inner wall of the hole of the nozzle has a part of the workpiece 155 that melts due to the accumulation of heat by the laser when the hole processing with a high aspect ratio is performed by laser ablation, and only that part rapidly It is thought to occur as processing progresses. This melting phenomenon does not occur in the case of a hole with a low aspect ratio because heat accumulation is small and only normal ablation processing is performed. As shown in FIG. 8, this melting phenomenon occurs when a conical small hole 605 having a diameter of about 10 μm is generated on the processing surface 215. When the laser is irradiated again to the place, the laser repeatedly reflects inside the small hole 605, and the small hole 605 grows in the depth direction and the lateral direction. The small holes 605 are grown in the lateral direction to form concave portions (horizontal holes) 307 formed in the inner wall of the hole. When the small holes 605 are further grown in the depth direction and separated from the hole center by about a radius, the hole 305 becomes a chip 305 on the outer periphery of the hole. The satellite 306 is considered to be larger than the radius of the shape.

  Based on these experimental considerations, in the first embodiment, it was considered necessary to suppress the occurrence of the melting phenomenon in order to suppress the generation of the nozzle small holes 605.

  Initially, in order to suppress the melting phenomenon, an attempt was made to reduce the heat intensity in the nozzle by reducing the laser intensity (power) during processing. However, even if the laser intensity is reduced, the generation of chip 305 and satellite 306 around the nozzle hole cannot be suppressed. Therefore, conversely, when the processing was performed with the laser intensity (power) increased during processing, it was possible to suppress the occurrence of chip 305 and satellite 306 on the outer periphery of the nozzle hole.

  Here, the reason why the generation of the chip 305 and the satellite 306 on the outer periphery of the nozzle hole can be suppressed by increasing the laser intensity will be considered.

When the laser intensity is small, when the hole processed in the nozzle becomes deep, the laser does not easily reach the processing surface 215 due to the processing powder or the hole side wall, ablation processing is not performed sufficiently, and a part of the laser energy is used as heat. Accumulated in the workpiece. When a certain depth (aspect ratio: about 2) is reached, melting is caused by the accumulated heat, and the aforementioned small holes 605 are considered to be generated on the processed surface 215 of the nozzle. On the other hand, when the laser intensity is high, even if the nozzle hole becomes deep, the laser sufficiently reaches the processing surface 215 and is sufficiently ablated, so that the laser energy is not accumulated in the nozzle as heat, and the small hole 605 It is considered that no occurrence occurs.

  That is, heat accumulates on the processing surface 215 of the workpiece 155 by the laser, a part of the workpiece 155 is melted, and a small hole 605 is generated. In this state, the laser is irradiated into the small hole 605 so that the laser causes internal reflection inside the small hole 605 to grow the small hole 605, and the concave portion processed on the inner wall of the hole by growing outside the original processing shape. (Horizontal hole) 307, and further grows to reach the workpiece bottom surface 205. By such a mechanism, it is considered that defects in the hole shape 210 such as the chip 305 around the hole outlet and the satellite 306 occur. Therefore, it can be seen that if the machining can be performed under the condition that the depression of the inner wall of the hole (small hole 605) does not occur, the nozzle machining without a defect can be finally performed.

  FIG. 9 is a flowchart showing the nozzle hole drilling method using the laser according to the first embodiment. As shown in FIG. 9, first, in step S701, test processing for determining laser intensity in advance is performed before the main processing. Subsequently, in step S702, the presence or absence of a recess (horizontal hole) 307 in the processed hole inner wall is confirmed by cleaving the processed hole inner wall (or inspecting using a probe or the like).

  If a recess (lateral hole) 307 is observed on the inner wall of the hole processed in step S702, the laser intensity is increased in step S710. When the concave portion (lateral hole) 307 is not observed on the inner wall of the hole processed in step S702, the workpiece 155 for main processing is supplied in step S720, and the main processing is performed in step S725.

  (Table 1) shows the relationship between the laser intensity and the occurrence of recesses (lateral holes) 307 on the processed hole inner wall.

（表１）に示すように、レーザ強度６４０ｍＪ／ｍｍ２以上では穴出口外周のカケ３０５や、サテライト３０６といった穴形状２１０の欠陥が発生しないということがわかる。レーザ強度６４０ｍＪ／ｍｍ２により再度２０００個の穴加工する本加工を行ったところ、２０００個全ての穴において、穴出口外周のカケ３０５及びサテライト３０６等の欠陥のない形状を得ることができた。この結果から、レーザ強度６４０ｍＪ／ｍｍ２以上とすることで、穴形状の欠陥が発生しないノズルの穴加工が可能であることが分かる。

As shown in Table 1, it can be seen that when the laser intensity is 640 mJ / mm 2 or more, defects in the hole shape 210 such as the chip 305 on the outer periphery of the hole outlet and the satellite 306 do not occur. When 2000 holes were drilled again with a laser intensity of 640 mJ / mm 2, it was possible to obtain a defect-free shape such as the chip 305 and satellite 306 at the outer periphery of the hole in all 2000 holes. From this result, it can be seen that by setting the laser intensity to 640 mJ / mm 2 or more, it is possible to perform drilling of a nozzle that does not cause a hole-shaped defect.

  A plasma display panel is produced by applying a phosphor paste to the plasma display panel and performing various treatments using the nozzles thus processed by the laser.

  In addition, according to the inventors' additional experiments, not only the ferritic stainless steel (for example, SUS430) described in the first embodiment, but also a martensitic stainless steel (for example, higher hardness than ferritic stainless steel) SUS420J2) and precipitation hardened stainless steel (for example, SUS630).

  In general, ferritic stainless steel can be drilled with a drill, but it is very difficult to drill a martensitic stainless steel or precipitation hardened stainless steel with a drill. Therefore, by using the present invention, it is possible to use these martensitic stainless steel and precipitation hardened stainless steel for the nozzle, and it is possible to provide a nozzle with higher hardness.

(Embodiment 2)
FIG. 10 is a flowchart showing a nozzle drilling method using a laser according to Embodiment 2 of the present invention. The second embodiment will be described with reference to the flowchart shown in FIG.

  In FIG. 10, first, in step S801, test processing for determining laser intensity in advance is performed before the main processing. Subsequently, in step S802, the processed inner wall of the hole is cleaved (or inspected using a probe or the like), thereby confirming the presence or absence of a recess (lateral hole) 307 in the processed inner wall of the hole.

  If a recess (lateral hole) 307 formed on the inner wall of the hole is observed in step S802, the laser intensity is increased in step S810. If the recess (lateral hole) 307 processed in the hole inner wall is not observed in step S802, the workpiece 155 for main processing is supplied in step S820, and main processing is started in step S825.

  Then, the first laser processing, that is, the pilot hole processing with the first laser intensity is started in step S830, the laser intensity is changed from the first laser processing to the second laser processing in step S835, and the second laser processing is performed in step S840. Laser processing, that is, finishing processing with the second laser intensity is performed.

  In the second laser processing, a laser having a lower laser intensity than that of the first laser processing is used. This is because the surface roughness and shape accuracy of the inner wall of the hole may not be sufficiently adjusted with the first laser intensity (laser intensity in the first embodiment), and so-called finishing laser processing must be performed. is there. Thereby, the hole processing which improved the surface roughness and shape accuracy of the hole inner wall of a nozzle can be performed.

  As described above, according to the nozzle hole drilling method using the laser according to the second embodiment, in the hole drilling with a high aspect ratio by the laser, precise hole drilling without defects such as burrs at the nozzle hole outlet is possible. It becomes.

Laser processing method and a method of manufacturing a nozzle according to the present invention, even when using a high hardness nozzle, because it is possible to suppress the deterioration with time, can be applied in the production of such a nozzle.

DESCRIPTION OF SYMBOLS 1 Coating device 2 Moving table 3 Head base 4 Display panel 5 Nozzle unit 6 Tank holder 7 Paste holder 8 Hole 101 Laser processing system 104 First mirror 105 Laser generating device 106 Optical system 107 Pulse laser beam 108 Second mirror 109 Laser measuring device 110 Shutter 115 Attenuator 120 Beam expander 125 Wave plate 130 Scan mirror 140 Telecentric lens 155 Work piece 202 Work piece surface 204 Laser incident direction 205 Work piece bottom face 210 Hole shape 215 Work surface 305 Chip 306 Satellite 307 Recess 501 Laser entrance Side 502 Laser exit side 605 Small hole 900 Hole exit surface 910 Ablation start point 920 Laser drive pattern 930 Perimeter line

Claims (6)

When a concave portion is observed on the inner wall of the hole in a test process performed in advance, adjustment is performed to increase the laser intensity until the concave portion is no longer observed, and the target is processed using a laser having the adjusted laser intensity of 640 mJ / mm 2 or more. Forming holes in objects,
Laser processing method. The workpiece is a martensitic stainless steel or precipitation hardened stainless steel plate, and the laser is a pulsed laser,
The laser processing method according to claim 1. The workpiece is a SUS430 plate, and the laser is a pulsed laser.
The laser processing method according to claim 1. The processed hole has an aspect ratio of 4 or more,
The laser processing method according to claim 2 or 3. When the concave portion processed in the inner wall of the hole is observed in a test process performed in advance, adjustment is performed to increase the laser intensity to a first laser intensity that is a laser intensity at which the concave portion is not observed, and the adjusted first Forming a hole in the workpiece by performing a second main processing with a second laser intensity lower than the first laser intensity.
The laser processing method of any one of Claims 1-4 . The workpiece is a nozzle;
The nozzle is manufactured using the laser processing method according to any one of claims 1 to 5 .
Nozzle manufacturing method.

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