JP2007167881A - Laser beam machining method and method for manufacturing ink-jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method and a method for manufacturing an ink-jet head by which resultants from machining can be easily removed by forming, in a plate, through holes having an opening part with a uniform edge shape and a small diameter error. <P>SOLUTION: The laser beam machining method in which an orifice 8 is formed in an orifice plate 1 by a laser beam 5 includes the steps of: installing a tacky adhesive film 4 on the ink-discharging face of the orifice plate 1; providing a fluidized layer 2 and an upper face protecting film 3 in this order on the laser irradiation surface of the orifice plate 1; forming the orifice 8 on the orifice plate 1 by irradiating the laser irradiation surface of the orifice plate 1 with the laser beam 5; removing the adhesive film 4 and the protecting film 3; and removing the fluidized layer 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing method for forming a through hole in a plate having a predetermined thickness, and a method for manufacturing an inkjet head including the plate.

  The ink-jet head includes a head main body that stores ink and an orifice plate in which an orifice that is an ink discharge port is formed. The orifice plate is a thin plate provided on the ink outlet surface of the head body. In order to improve the print quality of the inkjet head, it is desirable to make the shape of each orifice formed on the orifice plate uniform and to clean the surface of the orifice plate.

  The orifice is formed by irradiating the orifice plate with laser light from an excimer laser. By forming the orifice in the orifice plate, the scraped resin of the orifice plate is generated as a by-product such as carbon. The generated by-product accumulates in the vicinity of the opening on the ink ejection surface side and laser irradiation surface side of the orifice and in the ink flow path on the inner wall of the orifice. The by-product has strong adhesion to the orifice plate and is difficult to remove completely by ultrasonic cleaning or the like.

  When the by-product is attached in the vicinity of the opening on the ink ejection surface side of the orifice, and when the water-repellent film is formed after the orifice is formed, the formation of the water-repellent film is inhibited at the attached portion. The adhering site is hydrophilic. Even when the orifice is formed after the water repellent film is formed on the orifice plate, it is difficult to completely remove the by-product attached in the vicinity of the opening on the ink ejection surface side of the orifice. For this reason, an ink pool is generated at the adhering portion, and the straightness of the ink is lost. As a result, the print quality of the inkjet head decreases.

  When the by-product adheres to the vicinity of the opening on the laser irradiation surface side of the orifice and in the ink flow path, the by-product is clogged in the orifice by peeling or floating in the ink. As a result, the inkjet head becomes defective in ejection, and the print quality is deteriorated.

  FIG. 6 is a view showing a micrograph of the laser irradiation surface of the orifice formed by directly irradiating the orifice plate with laser light. Here, after the orifice is formed, the orifice plate is subjected to ultrasonic cleaning with a neutral detergent and an organic solvent. As shown in FIG. 6, by-products are deposited around the opening on the laser irradiation surface side of the orifice. Since the by-product is difficult to remove by ultrasonic cleaning or the like, it is necessary to remove the by-product using a method such as plasma ashing.

  A technique for solving the above problem is disclosed in Patent Document 1. In Patent Document 1, by applying a liquid that can be easily removed onto the laser irradiation surface of an orifice plate, a by-product generated during the formation of the orifice is transferred to the liquid, and the liquid is removed. Thereby, the laser irradiation surface of the orifice plate can be kept clean.

  However, in the above configuration, the byproduct attached to the laser irradiation surface side of the orifice plate can be removed, but the byproduct attached to the ink ejection surface side cannot be removed. Therefore, conventionally, the following laser processing methods are used. A conventional laser processing method will be described below with reference to FIG. 7A to 7D are cross-sectional views showing a conventional laser processing method.

  As shown in FIG. 7A, the laser irradiation surface to which the laser beam of the plate 91 before forming the orifice (hereinafter referred to as the orifice plate) is irradiated has a viscosity that can be easily removed, for example, polypropylene. A liquid 92 such as glycol and an upper surface protective film 93 are provided in this order. Further, a liquid 92 and a lower surface protective film 94 are provided in this order on the ink ejection surface, which is the surface opposite to the laser irradiation surface of the orifice plate 91. Then, a mask pattern (not shown) having a plurality of holes formed on the upper surface of the upper surface protective film 93 is provided. The orifice 98 is formed by irradiating the excimer laser beam 95 on the mask pattern. Here, ablation processing is performed to a part of the lower surface protective film 94 by the laser beam 95 through the upper surface protective film 93, the liquid 92, and the orifice plate 91. Then, a by-product 96 generated by forming the orifice 98 is deposited on the upper surface of the upper surface protective film 93.

  Next, as shown in FIG. 7B, after the orifice 98 is formed, the upper surface protective film 93 and the lower surface protective film 94 are removed. The liquid 92 applied to the laser irradiation surface and the ink ejection surface of the orifice plate 91 is ultrasonically cleaned with an organic solvent. Thereby, as shown in FIG.7 (c), the clean orifice plate 91 in which the by-product 96 does not adhere is obtained.

Next, as shown in FIG. 7D, a water repellent layer 97 is formed on the ink ejection surface of the orifice plate 91.
No. 10-505557 (International publication date March 21, 1996)

  However, in the conventional configuration described above, the shape of the edge of the opening on the ink ejection surface side of the orifice 98 is distorted as shown in FIG. FIG. 8 is a view showing an SEM photograph of the ink ejection surface side of the orifice 98 formed by the conventional laser processing method shown in FIG.

  When forming the orifice, a mask pattern provided with a plurality of holes is provided on the upper surface protective film 93, and a laser beam 95 is irradiated from the mask pattern. As a result, a plurality of orifices 98 are formed in the orifice plate 91 at a time. In the conventional laser processing method, the roundness of the hole formed in the mask pattern (variation of the diameter of the circle) is 0.1 μm, whereas the roundness of the formed orifice 98 is 1.5 μm. ing.

  FIG. 9 is a graph obtained by measuring the diameter of the opening on the ink ejection surface side of the orifices 98 formed in a lump by the conventional laser processing method shown in FIG. In the figure, the Y axis indicates the diameter of the opening, and one scale is 0.5 μm. The X axis indicates the number of orifices formed at once (hereinafter referred to as the number of channels). As shown in FIG. 9, the diameter of the opening for each channel shows a variation of about 1.2 μm at the maximum.

  Thus, in the conventional laser processing method, the opening on the ink ejection surface side of the formed orifice 98 has an irregular edge shape and a variation in diameter. If the shape of the edge of the opening becomes distorted, the direction of ink ejected from the orifice 98 varies. In addition, when the diameter of the opening varies, the amount of ink ejected from the inkjet head differs at each orifice 98. As a result, the print quality of the inkjet head including the orifice plate in which the orifice 98 is formed by the conventional laser processing method is deteriorated.

  The present invention has been made in view of the above problems, and its purpose is to form a through-hole in the plate with a uniform edge shape of the opening and a small error in the diameter of the opening. Provided are a laser processing method and an ink jet head manufacturing method capable of easily removing a generated product.

  In order to solve the above problems, the laser processing method of the present invention is a laser processing method in which a through hole is formed in a plate by laser light. On the surface opposite to the laser irradiation surface irradiated with the laser light of the plate. A step of providing an adhesive film having adhesive strength, a step of providing a fluidized bed having fluidity on the laser irradiation surface of the plate and a protective film in this order, and a laser beam for the laser irradiation surface of the plate. And forming a through hole in the plate, removing the adhesive film and the protective film, and removing the fluidized bed.

  In the conventional laser processing method, since the viscosity of the liquid applied to the surface of the plate opposite to the laser irradiation surface is low, the stability of the plate is low. For this reason, when the plate is irradiated with a laser, the plate moves to cause a focus position shift of the laser. Further, the adhesion between the plate and the protective film provided on the liquid is weak, and the impact of laser irradiation is dispersed in the liquid. Then, due to the impact dispersed in the liquid, the shape of the edge of the opening on the surface side of the formed through hole opposite to the laser irradiation surface of the plate becomes distorted.

  In the present invention, the stability and adhesion between the plate and the adhesive film can be improved by providing an adhesive film having adhesive force on the surface opposite to the laser irradiation surface of the plate. For this reason, the laser processing method of the present invention forms a through hole in which the shape of the edge of the opening on the surface opposite to the laser irradiation surface of the plate is uniform and the variation in the diameter of the opening is small. Can do.

  Further, by providing an adhesive film and a protective film on both sides of the laser irradiation surface and the surface opposite to the laser irradiation surface of the plate, the by-products generated by forming the through holes adhere to the plate. To suppress. And since the said fluidized bed can be removed easily, the clean plate which has an elaborate through-hole can be obtained.

In the laser processing method of the present invention, the plate is preferably made of a polymer having an optical absorption coefficient of 1000 cm ⁻¹ or more for an excimer laser having a wavelength of 248 nm.

In general, ablation processing is the center of processing using an excimer laser. Therefore, the processing state of the material to be processed depends on the light absorption coefficient of the material. That is, if the light absorption coefficient of the material is below a certain threshold value, it cannot be processed by an excimer laser having a predetermined power. Therefore, the light absorption coefficient of the plate needs to be a certain value or more. In the above configuration, since the plate is made of a polymer having a light absorption coefficient of 1000 cm ⁻¹ or more, it is possible to easily perform ablation using an excimer laser having a wavelength of 248 nm.

  Moreover, in the laser processing method of this invention, the said plate may be comprised from the material containing a polyimide derivative.

  Accordingly, the plate has a light absorption coefficient that can be suitably processed by an excimer laser having a wavelength of 248 nm. Therefore, the plate can be easily ablated using an excimer laser.

  Moreover, in the laser processing method of this invention, it is preferable that the adhesive force of the surface on the opposite side to the laser irradiation surface of the said plate and the said adhesive film is 0.5 N / 20mm or more.

  Thereby, stability and adhesiveness of the said plate and the said adhesive film can be improved. Therefore, in the laser processing method of the present invention, the shape of the edge of the opening on the surface of the formed through hole opposite to the laser irradiation surface of the plate is uniform, and the diameter of the opening varies. Small through holes can be formed.

  In the laser processing method of the present invention, the viscosity of the fluidized bed is preferably 40 cP or less at 25 ° C.

  In the conventional laser processing method, since the viscosity of the liquid applied to the laser irradiation surface of the plate is high, the liquid does not spread over the entire laser irradiation surface, and the protective film provided on the liquid swells. . Therefore, when the protective film is irradiated with a laser, the focus position shift of the laser occurs.

  In the present invention, when the adhesion rate of the fluidized bed is set to 40 cP or less at 25 ° C., the fluidized bed spreads evenly over the entire laser irradiation surface of the plate, and the undulation generated in the protective film provided on the fluidized bed. Can be suppressed. Therefore, the focus position shift due to laser irradiation is suppressed, and variation in the diameter of the opening on the surface of the formed through hole opposite to the laser irradiation surface of the plate can be reduced.

  In the laser processing method of the present invention, the fluidized bed may be made of polypropylene glycol.

  In the above method, since polypropylene glycol has low reactivity with the plate, the influence on the plate can be reduced by using polypropylene glycol as the fluidized bed. For this reason, a cleaner plate having an elaborate through hole can be obtained.

Moreover, in the laser processing method of this invention, it is preferable that the said protective film is comprised from the polymer whose optical absorption coefficient with respect to the excimer laser with a wavelength of 248 nm is 1000 cm < ^-1 > or more.

In the above method, by forming both the first protective film and the plate from a polymer having an optical absorption coefficient of 1000 cm ⁻¹ or more for an excimer laser having a wavelength of 248 nm, a clean plate having more elaborate through holes can be obtained. it can.

  The inkjet head manufacturing method of the present invention is a method for manufacturing an inkjet head in which an orifice is formed on an orifice plate by laser light, and a water repellent film on a surface opposite to the laser irradiation surface irradiated with the laser light of the orifice plate Forming a pressure-sensitive adhesive film on the surface opposite to the laser irradiation surface of the orifice plate, and a fluidized bed having fluidity on the laser irradiation surface of the orifice plate, A step of providing a protective film in this order; a step of irradiating a laser irradiation surface of the orifice plate with laser light to form an orifice; a step of removing the adhesive film and the protective film; And a step of removing.

  In the above method, a water repellent film is formed on the surface of the orifice plate opposite to the laser irradiation surface before forming the orifice. As a result, a by-product generated by forming the orifice does not affect the formation of the water-repellent film, and a cleaner orifice plate can be formed as compared with the conventional method of forming the water-repellent film after forming the orifice. It is possible to obtain.

  Further, by providing an adhesive film having adhesive force on the surface opposite to the laser irradiation surface of the orifice plate, the stability and adhesion between the orifice plate and the adhesive film can be enhanced. For this reason, the inkjet head manufacturing method of the present invention forms an orifice having a uniform edge shape on the surface opposite to the laser irradiation surface of the orifice plate and a small variation in the diameter of the opening. can do.

  In addition, by providing an adhesive film and a protective film on both sides of the laser irradiation surface of the orifice plate and the surface opposite to the laser irradiation surface, by-products generated by forming the orifice adhere to the orifice plate. To suppress. For this reason, a clean orifice plate having a fine orifice can be obtained.

  In the inkjet head manufacturing method of the present invention, the water repellent film is preferably composed of a fluorine-based silane coupling agent.

  Thereby, the water-repellent film can be formed very thin. This is because the fluorine-based silane coupling agent has water repellency even with a monomolecular film (2 to 3 nm), and a water-repellent film can be formed very thin compared to other water-repellent materials. For this reason, the influence which it has on the shape of the orifice in the surface side on the opposite side to the laser irradiation surface of the said orifice plate can be made small. In addition, the range of applicable laser processing conditions is wider than other water-repellent materials, and an orifice can be easily formed.

  Further, the ink jet head manufacturing method of the present invention is characterized in that the through hole of the plate formed by the laser processing method described above is used as an ink discharge port.

  By the above method, the through-hole of the plate formed by the laser processing method described above is used as an ink discharge port of the inkjet head. Thereby, an inkjet head can be manufactured using the clean plate which has an elaborate through-hole.

  As described above, the laser processing method of the present invention includes the step of providing an adhesive film having adhesive force on the surface opposite to the laser irradiation surface irradiated with the laser light of the plate, and the laser irradiation surface of the plate. And a step of providing a fluidized bed having fluidity and a protective film in this order.

  In addition, as described above, the inkjet head manufacturing method of the present invention includes the step of forming a water repellent film on the surface opposite to the laser irradiation surface irradiated with the laser light of the orifice plate, and the laser of the orifice plate. A step of providing an adhesive film having adhesive force on the surface opposite to the irradiation surface, and a step of providing a fluidized bed having fluidity and a protective film in this order on the laser irradiation surface of the orifice plate. .

  Therefore, there is provided a laser processing method and an inkjet head manufacturing method in which a through-hole having a uniform edge shape and a small error in the diameter of the opening is formed in the plate, and a product generated by the processing can be easily removed. There is an effect that can be done.

  One embodiment of the present invention will be described below. First, a study of a conventional laser processing method will be described.

[Examination of conventional laser processing methods]
As described above, in the conventional laser processing method, the opening on the ink ejection surface side of the formed orifice has an irregular edge shape and a variation in diameter occurs. The above problem is considered to be caused by the adhesive liquid applied to the laser irradiation surface and the ink ejection surface of the orifice plate. Therefore, the cause of the above problem will be examined with reference to FIG. 10 and FIG.

  FIG. 10A is a cross-sectional view showing a configuration for examining the influence of the liquid applied to the laser irradiation surface side of the orifice plate on the orifice formation. FIG. 10B is a cross-sectional view showing a configuration for examining the influence of the liquid applied to the ink ejection surface side of the orifice plate on the formation of the orifice.

  First, as shown in FIG. 10A, the liquid 12 is applied to the laser irradiation surface of the orifice plate 11, and the upper surface protective film 13 is provided thereon. Then, the upper surface of the upper surface protective film 13 is irradiated with a laser beam 15 through a mask pattern formed by chromium deposition on a quartz substrate. By irradiating the laser beam 15, the upper surface protective film 13 and the orifice plate 11 are scraped, and a by-product 16 is deposited on the upper surface protective film 13. Since the main component of the by-product 16 is carbon, it can be removed by ashing, but plasma damage to the orifice plate 11 occurs.

  In the above process, the liquid 12 is made of polypropylene glycol (PPG: molecular weight 2000, viscosity of 163.7 cP at 25 ° C.), the orifice plate 11 is made of a polyimide film having a thickness of 50 μm, and the upper surface protective film 13 is made of A polyimide film having a thickness of 12.5 μm is used. The laser beam 15 is irradiated by an excimer laser having a wavelength of 248 nm. The excimer laser is set so that the diameter of the opening on the laser irradiation surface side of the orifice is about 40 μm and the diameter of the opening on the ink ejection surface side is about 20 μm.

  Further, in order to study the influence of the liquid applied to the ink discharge surface side of the orifice plate on the orifice formation, the liquid 12 is applied to the ink discharge surface of the orifice plate 11 as shown in FIG. The lower surface protective film 14 is provided thereon. Then, the laser beam 15 is irradiated onto the laser irradiation surface of the orifice plate 11 through the mask pattern. In the above process, a polyimide film having a thickness of 75 μm is used for the lower surface protective film 14. In addition, about the other member, the thing similar to the member used in Fig.10 (a) is used.

  By the above method, it is possible to confirm the influence of the liquid 12 applied to the laser irradiation surface and the ink ejection surface of the orifice plate 11 on the orifice formation.

  11 (a) and 11 (b) show the diameter of the opening on the ink ejection surface side of the orifice when a plurality of orifices are collectively laser processed with the configuration of FIGS. 10 (a) and 10 (b). It is the figure which showed the dispersion | variation. In the figure, the Y axis indicates the diameter of the opening, and one scale is 0.5 μm. The X axis indicates the number of orifices formed at once (hereinafter referred to as the number of channels). When laser processing is performed with the configuration of FIG. 10A, the diameter of the opening for each channel shows a variation of about 0.7 μm at the maximum. When laser processing is performed in the configuration of FIG. 10B, the diameter of the opening for each channel shows a variation of about 1.3 μm at the maximum. Although not shown, the shape of the edge of the opening on the ink ejection surface side of the orifice is the laser processing with the configuration of FIG. 10B compared to the case of laser processing with the configuration of FIG. If you do, you will be more angry.

  From the above, it is determined that the shape of the edge of the opening on the ink ejection surface side of the orifice and the diameter of the opening greatly depend on the material provided on the ink ejection surface side of the orifice plate.

[Laser processing method of this embodiment]
An embodiment of the present invention will be described below with reference to FIGS.

  With reference to FIG. 1 and FIG. 2, the laser processing method of this embodiment is demonstrated. 1A to 1C are cross-sectional views illustrating a laser processing method according to the present embodiment. FIG. 2 is a flowchart showing the laser processing method of this embodiment.

  First, the water repellent film 7 is formed on the ink ejection surface of the orifice plate (plate) 1 (S1).

  Next, as shown in FIG. 1A, the adhesive film 4 is provided on the water repellent film 7 (S2). Further, a fluidized bed 2 is provided on the laser irradiation surface of the orifice plate 1 (S3), and an upper surface protective film (protective film) 3 is provided thereon. Then, the orifice plate 1, the fluidized bed 2 and the upper surface protective film 3 are laminated at room temperature (25 ° C.) (S4). Then, a laser beam (laser light) 5 is irradiated from above the upper surface protective film 3 to form an orifice 8 (S5). The processing by the laser beam 5 is performed from the upper surface of the upper surface protective film 3 to the adhesive film 4 through the fluidized bed 2 and the orifice plate 1. At that time, the by-product 6 generated by scraping each member is deposited on the upper surface of the upper surface protective film 3 and in the vicinity of the opening of the formed orifice 8.

  Next, as shown in FIG.1 (b), the upper surface protection film 3 and the adhesion film 4 are peeled from the fluidized bed 2 (S6). Then, the orifice plate 1 is ultrasonically cleaned using an organic solvent, and the fluidized bed 2 provided on the laser irradiation surface of the orifice plate 1 is cleaned (S7). Thereby, as shown in FIG.1 (c), the clean orifice plate 1 in which the by-product 6 produced by laser processing does not adhere can be obtained.

  The formed orifice 8 has a so-called taper shape in which the diameter becomes smaller as it goes from the laser irradiation surface of the orifice plate 1 to the ink ejection surface.

  The laser processing method of this embodiment is used for forming an orifice of an orifice plate provided in an ink jet head. In addition, the laser processing method of this invention is not restricted to the use mentioned above, It can be used in order to form a through-hole in a plate.

  The water repellent film 7 is for suppressing ink from adhering to the ink ejection surface side of the orifice plate 1. In the present embodiment, the water repellent film 7 is formed on the ink ejection surface of the orifice plate 1 before the orifice 8 is formed. As a result, the by-product 6 generated by forming the orifice 8 does not affect the formation of the water-repellent film 7, and is cleaner than the conventional method of forming the water-repellent film after forming the orifice. It is possible to obtain an orifice plate 1.

  In the present embodiment, the water repellent film 7 is composed of a fluorine-based silane coupling agent. Since the fluorinated silane coupling agent has water repellency even with a monomolecular film (2 to 3 nm), the water repellent film 7 can be formed very thin compared to other water repellent materials. Therefore, the influence of the water repellent film 7 on the shape of the orifice 8 on the ink ejection surface side of the orifice plate 1 can be reduced. In addition, the range of applicable laser processing conditions is wider than other water-repellent materials, and an orifice can be easily formed.

  In this embodiment, the water repellent film 7 is formed on the ink ejection surface side of the orifice plate 1 before the orifice 8 is formed, but the present invention is not limited to this. That is, the water repellent film 7 may be formed on the ink ejection surface side of the orifice plate 1 after the orifice 8 is formed. In the laser processing method of the present invention, the water repellent film 7 may not be formed.

  The laser beam 5 is for forming the orifice 8 in the orifice plate 1. The laser beam 5 is irradiated by an excimer laser having a wavelength of 248 nm. The excimer laser is set so that the diameter of the opening on the laser irradiation surface side of the orifice 8 is about 40 μm and the diameter of the opening on the ink ejection surface side is about 20 μm.

  The orifice plate 1 is an ink jet head in which an orifice that is an ejection port for ejecting ink is formed. In general, ablation processing is the center of processing using an excimer laser. Therefore, the processing state of the material to be processed depends on the light absorption coefficient of the material. That is, if the light absorption coefficient of the material is below a certain threshold value, it cannot be processed by an excimer laser having a predetermined power. Therefore, in order to form the orifice 8 in the orifice plate 1 by the laser beam 5, the light absorption coefficient of the orifice plate 1 needs to be a certain value or more.

Therefore, in the present embodiment, the orifice plate 1 is made of a polymer having a light absorption coefficient of 1000 cm ⁻¹ or more with respect to an excimer laser having a wavelength of 248 nm. The polymer is mainly composed of a material containing a polyimide derivative. In addition to the polyimide derivative, polystyrene, polyamide, polymethyl methacrylate, and the like can be used as the polymer. Thereby, it becomes possible to easily ablate the orifice plate 1 using an excimer laser having a wavelength of 248 nm. Moreover, since the said polymer containing the polyimide derivative is excellent in chemical resistance, it can be used suitably also as a nozzle of an inkjet head.

The upper surface protective film 3 is for preventing the by-product 6 generated by the formation of the orifice 8 from adhering to the laser irradiation surface of the orifice plate 1. Similar to the orifice plate 1, the upper surface protective film 3 is made of a polymer having a light absorption coefficient of 1000 cm ⁻¹ or more for an excimer laser having a wavelength of 248 nm. Since the polymer used is the same as that of the orifice plate 1, description thereof is omitted. Thus, by forming the upper surface protective film 3 from the material having the same configuration as that of the orifice plate 1, it is possible to obtain a clean orifice plate 1 having the orifice 8 formed more elaborately.

  Here, the configuration of the fluidized bed 2 and the adhesive film 4 used in the laser processing method of the present embodiment will be described based on the results obtained by examining the conventional laser processing method shown in FIGS. 10 and 11.

  In the conventional laser processing method, since the viscosity of the liquid applied to the ink ejection surface of the orifice plate is low, the stability of the orifice plate is low. For this reason, when the orifice plate is irradiated with the laser beam, the orifice plate moves to cause a focus position shift of the laser beam. Further, the adhesion between the orifice plate and the lower surface protective film is weak, and the impact of laser irradiation is dispersed in the liquid. Due to the impact dispersed in the liquid, the shape of the edge of the opening on the ink ejection surface side of the orifice plate becomes distorted.

  Further, since the viscosity of the liquid applied to the laser irradiation surface of the orifice plate is high, the liquid does not spread over the entire laser irradiation surface, and undulation occurs in the upper surface protective film provided on the liquid. Therefore, when the upper surface protective film is irradiated with a laser beam, a focus position shift of the laser beam occurs.

  Therefore, in the present embodiment, by providing the viscosity of the fluidized bed 2 and the adhesive force between the ink ejection surface of the orifice plate 1 and the adhesive film 4, the opening on the ink ejection surface side of the orifice 8 is provided. Variation in the diameter of the openings is made uniform, and the shape of the edge of the opening is made uniform.

  The fluidized bed 2 is for adhering the upper surface protective film 3 to the laser irradiation surface of the orifice plate 1. As described above, conventionally, the viscosity of the liquid applied to the ink ejection surface of the orifice plate has caused undulation in the upper surface protective film provided on the liquid, resulting in a shift of the laser focus position. . For this reason, the viscosity of the fluidized bed 2 is preferably low to some extent. Specifically, the viscosity of the fluidized bed 2 is preferably 40 cP or less.

  In this embodiment, polypropylene glycol (PPG) having a molecular weight of 400 (viscosity at 25 ° C .: 40 cP) is used as the fluidized bed 2. Thereby, the fluidized bed 2 spreads over the entire laser irradiation surface of the orifice plate 1, and the upper surface protective film 3 does not swell. For this reason, the focus position of the laser does not shift, and the orifice 8 having a small variation in the diameter of the opening on the ink ejection surface side of the orifice plate 1 can be formed. Further, by using PPG having low reactivity with the orifice plate 1 as the fluidized bed 2, the influence on the orifice plate 1 can be reduced. For this reason, a cleaner orifice plate 1 having an elaborate orifice 8 can be obtained.

  In the present embodiment, the fluidized bed 2 uses PPG having a molecular weight of 400 (viscosity at 25 ° C .: 40 cP), but the present invention is not limited to this. For example, a fluid material such as a sol may be used (refers to a material having a viscosity of 10,000 cP or less).

  The adhesive film 4 is for preventing the by-product 6 generated by the formation of the orifice 8 from adhering to the ink ejection surface side of the orifice plate 1. In the present embodiment, a product name “SPV-224” manufactured by Nitto Denko is used as the adhesive film 4. The adhesive film 4 is not limited to the one described above, and any adhesive film may be used as long as the adhesive force with the ink ejection surface of the orifice plate 1 is 0.5 N / 20 mm or more. Thereby, stability and adhesiveness of the orifice plate 1 and the adhesive film 4 can be improved. Therefore, the laser processing method of the present embodiment can form the orifice 8 having a uniform edge shape on the ink ejection surface side of the orifice plate 1 and a small variation in the diameter of the opening.

  Next, the state of the orifice plate 1 in which the orifice 8 is formed by the laser processing method of the present embodiment will be described with reference to FIGS.

  FIG. 3 is a view showing an SEM photograph of the ink ejection surface side of the orifice 8 formed by the laser processing method of the present embodiment. As shown in FIG. 3, the orifice 8 formed by the laser processing method of this embodiment has a uniform edge shape on the ink ejection surface side of the orifice plate 1. The roundness of the mask pattern used for forming the orifice 8 (variation in the diameter of the circle) is 0.1 μm, whereas the roundness of the opening on the ink ejection surface side of the orifice 8 is 0.5 μm. It is. Thus, by using the laser processing method of this embodiment, it is possible to form a very elaborate orifice 8.

  FIG. 4 is a graph obtained by measuring the diameter of the opening on the ink ejection surface side of the orifices 8 collectively formed by the laser processing method of the present embodiment. In the figure, the Y axis indicates the diameter of the opening, and one scale is 0.5 μm. Further, the X axis indicates the number of orifices 8 formed collectively (hereinafter referred to as the number of channels). In the conventional laser processing method, the diameter of the opening for each channel showed a variation of about 1.2 μm at the maximum, but in the laser processing method of the present embodiment, the diameter is about 0.5 μm at the maximum. As described above, in the laser processing method of the present embodiment, the variation in the diameter of the opening on the ink ejection surface side of the formed orifice 8 is smaller than that in the conventional case.

  FIG. 5 is a view showing a micrograph of the laser irradiation surface of the orifice 8 formed by the laser processing method of the present embodiment. In FIG. 5, the orifice plate 1 in which the orifice 8 is formed by the laser processing method of this embodiment is ultrasonically cleaned using an organic solvent. As described above, in the laser processing method of the present embodiment, by washing the orifice plate 1 after forming the orifice 8, the by-product seen in the conventional laser processing method is removed, and the laser irradiation surface is kept clean. It is.

  As described above, the laser processing method of this embodiment is a method of forming the orifice 8 in the orifice plate 1 by the laser beam 5, and the adhesive film 4 having adhesive force is provided on the ink ejection surface of the orifice plate 1. Irradiating the laser beam 5 to the laser irradiation surface of the orifice plate 1, the step of providing the fluidized bed 2 having fluidity on the laser irradiation surface of the orifice plate 1 and the upper surface protective film 3 in this order; Forming the orifice 8 in the orifice plate 1, removing the adhesive film 4 and the upper surface protective film 3, and removing the fluidized bed 2.

  Thus, by providing the adhesive film 4 having adhesive force on the ink ejection surface side of the orifice plate 1, the stability and adhesion between the orifice plate 1 and the adhesive film 4 can be enhanced. Therefore, the laser processing method of the present embodiment can form the orifice 8 having a uniform edge shape on the ink ejection surface side of the orifice plate 1 and a small variation in the diameter of the opening.

  In addition, by providing the adhesive film 4 and the upper surface protective film 3 on both sides of the laser irradiation surface and the ink ejection surface of the orifice plate 1, the by-product 6 generated by forming the orifice 8 adheres to the orifice plate 1. To suppress that. For this reason, the clean orifice plate 1 having the fine orifice 8 can be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  The present invention is suitably used when a through hole is formed in a plate, or when an orifice is formed in an orifice plate provided in an ink jet head.

It is sectional drawing which shows one Embodiment of the laser processing method in this invention. It is a flowchart which shows the said laser processing method. It is the figure which showed the SEM photograph of the discharge port of the orifice formed by the said laser processing method. It is a graph which shows the measured value of the diameter of the opening part in the ink discharge surface side of the orifice collectively formed by the said laser processing method. It is the figure which showed the microscope picture of the laser irradiation surface of the orifice formed by the said laser processing method. It is the figure which showed the microscope picture of the laser irradiation surface of the orifice formed by performing laser irradiation directly to an orifice plate. (A)-(d) is sectional drawing which shows the conventional laser processing method. It is the figure which showed the SEM photograph by the side of the ink discharge surface of the orifice formed by the conventional laser processing method. It is a graph which shows the measured value of the diameter of the opening part in the ink discharge surface side of the orifice formed collectively by the conventional laser processing method. (A) is sectional drawing which showed the structure for examining the influence which the liquid apply | coated to the laser irradiation surface side of an orifice plate has on orifice formation, (b) is the ink discharge surface side of an orifice plate. It is sectional drawing which showed the structure for examining the influence which the apply | coated liquid has on orifice formation. 10A is a diagram showing variation in the diameter of the opening on the ink ejection surface side of the orifice when a plurality of orifices are collectively laser-processed with the configuration of FIG. 10A, and FIG. It is the figure which showed the dispersion | variation in the diameter of the opening part in the ink discharge surface side of an orifice at the time of carrying out the batch laser processing of the several orifice with the structure of 10 (b).

Explanation of symbols

1 Orifice plate (plate)
2 Fluidized bed 3 Upper surface protective film (protective film)
4 Adhesive film 5 Laser beam (laser beam)
6 By-product 7 Water repellent film 8 Orifice (through hole)

Claims (10)

In a laser processing method for forming a through hole in a plate by laser light,
A step of providing an adhesive film having adhesive force on the surface opposite to the laser irradiation surface irradiated with the laser light of the plate;
A step of providing a fluidized bed having fluidity and a protective film in this order on the laser irradiation surface of the plate;
Irradiating the laser irradiation surface of the plate with laser light to form a through hole in the plate;
Removing the adhesive film and the protective film;
And a step of removing the fluidized bed. The laser processing method according to claim 1, wherein the plate is made of a polymer having a light absorption coefficient of 1000 cm ⁻¹ or more for an excimer laser having a wavelength of 248 nm.   The laser processing method according to claim 1, wherein the plate is made of a material containing a polyimide derivative.   The laser processing method according to claim 1, wherein the adhesive force between the surface of the plate opposite to the laser irradiation surface and the adhesive film is 0.5 N / 20 mm or more.   The laser processing method according to claim 1, wherein the fluidized bed has a viscosity of 40 cP or less at 25 ° C.   The laser processing method according to claim 1, wherein the fluidized bed is made of polypropylene glycol. The laser processing method according to claim 2, wherein the protective film is made of a polymer having a light absorption coefficient of 1000 cm ⁻¹ or more for an excimer laser having a wavelength of 248 nm. In an inkjet head manufacturing method for forming an orifice in an orifice plate by laser light,
Forming a water repellent film on a surface opposite to the laser irradiation surface irradiated with the laser light of the orifice plate;
Providing an adhesive film having adhesive force on the discharge surface of the orifice plate;
A step of providing a fluidized bed having fluidity and a protective film in this order on the laser irradiation surface of the orifice plate;
Irradiating laser light to the laser irradiation surface of the orifice plate to form an orifice;
Removing the adhesive film and the protective film;
And a step of removing the fluidized bed.   9. The method of manufacturing an ink jet head according to claim 8, wherein the water repellent film is composed of a fluorine-based silane coupling agent.   An ink jet head manufacturing method, wherein a through hole of a plate formed by the laser processing method according to claim 1 is used as an ink discharge port.

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