JP2009262216A - Laser beam machining method for transparent base material, and manufacturing method for electrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method for a transparent base material, in which a super-fine, machined hole of high aspect ratio is efficiently formed with high accuracy, and a manufacturing method for an electrolyte membrane using a porous transparent base material formed by using the method. <P>SOLUTION: One side surface side of a light-transmissive transparent base material W is set in an evacuated atmosphere, and the one side surface side is brought into contact with a light-absorptive opaque liquid F. The interference light L3 of the ultra-short pulsed laser is emitted from the other side surface side of the transparent base material W and allowed to pass through the transparent base material. By concentrating the laser beam energy of the interference light in a vicinity of the interface between the transparent base material W and the opaque liquid F, a super-fine, machined hole P is formed in the transparent base material W. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to, for example, a laser processing method for forming fine processed holes with a laser beam on a transparent substrate made of resin, and a method of manufacturing an electrolyte membrane from a porous transparent substrate manufactured by the laser processing method. It is about.

  2. Description of the Related Art Conventionally, as a method for finely processing fine holes or the like in a transparent substrate made of resin such as plastic, there are methods of applying a fine processing apparatus and a processing method as disclosed in Patent Documents 1 and 2.

  In this method, a fluid material having a high absorption rate with respect to the laser wavelength is brought into contact with the back surface of the transparent material, and the laser beam is irradiated from the front surface so that the energy density of the laser beam is applied to the interface between the transparent material and the fluid material. By concentrating, the back surface of the transparent material is drilled.

  According to the above processing method, it is possible to efficiently perform the hole processing by concentrating the laser energy on the processing portion of the transparent material. On the other hand, as the size of the processing hole becomes finer, the surface of the fluid substance Due to the tension or the like, it becomes difficult for the fluid substance to enter the micropores, and there is a problem that micropore processing with high processing accuracy cannot be performed.

  Furthermore, in the above apparatus, since there are minute irregularities and scratches on the surface of the transparent material, that is, the surface on which the laser is irradiated, the laser beam is scattered by the irregularities and the required energy density. There is also a problem that the processing site cannot be irradiated with the laser having the.

JP 2004-306134 A Japanese Patent No. 3012926

  The present invention has been made in view of the above-described problems. For example, when forming fine processed holes with a laser beam on a resin-made transparent substrate, high-quality fine holes are efficiently manufactured. An object of the present invention is to provide a laser processing method for a transparent substrate, and a method for producing an electrolyte membrane capable of producing a high-quality electrolyte membrane using a porous transparent substrate produced by the laser processing method. To do.

  In order to achieve the above object, a laser processing method for a transparent substrate according to the present invention is such that one side of a light transmissive transparent substrate is brought into a reduced pressure atmosphere, and the one side is brought into contact with a light absorbing opaque liquid. The interference light of the ultrashort pulse laser light is irradiated from the other side of the transparent base material to transmit the transparent base material, and the laser energy of the interference light is concentrated near the interface between the transparent base material and the opaque liquid. By doing so, finely processed holes are formed in the transparent substrate.

  The laser processing method of the present invention is intended for use in the production of a porous transparent substrate for a pore filling electrolyte membrane used in, for example, a fuel cell. Examples include fluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polyethylene terephthalate, polyethylene, polypropylene, and polyimide.

  This laser processing method uses an ultra-short pulse laser beam. By using this laser beam, even if it has the same energy as other laser beams, its pulse width is extremely small, and therefore its power peak. The value of can be increased. In order to form an ultrafine through-hole having a diameter of about 100 nm (nanometer) on a transparent substrate, picosecond laser light or femtosecond laser light that causes multiphoton absorption is used among ultrashort pulse laser light. Is desirable.

  In the laser processing method of the present invention, a transparent base material is accommodated in a container such as a vacuum container, a light-absorbing opaque liquid is brought into contact with one side surface of the transparent base material, and ultrashort pulse laser light is interfered from the other side surface. It irradiates light. Within this interference light band, strong and weak parts of continuous light are formed at a constant period, and the laser light overlaps to the maximum near the boundary between the light-transmitting transparent substrate and the light-absorbing opaque liquid. By combining the locations, a plurality of microfabricated holes can be formed at a time in the transparent substrate. Here, by adjusting the movement of the transparent base material according to the processing progress of the processing hole, or by adjusting the movement of the laser driving device for the ultrashort pulse laser light, the laser beam is maximized at the bottom of the processing hole in real time. The place to wrap can be matched. The interference light described above is formed, for example, by diffracting (separating) ultrashort pulse laser light emitted from a laser oscillator into a plurality of light beams through a diffraction grating and passing through two condenser lenses. Can do. Further, the change in the interface position according to the processing progress may be sensed by a sensor such as a CCD camera, and the transparent substrate or the laser driving device may be moved and adjusted by the driving device based on the sensing data.

  Here, as the above-mentioned opaque liquid, an organic solvent, a high-concentration alkaline solution, or the like can be used. As the organic solvent, n-methyl-2-pyrrolidone, N, N-dimethylformamide, or the like can be used. Caustic soda or the like can be used as the high concentration alkaline solution. Further, in addition to the opaque liquid being used alone, a liquid obtained by adding a dye, a pigment or the like to the opaque liquid may be used in order to further increase the light absorption.

  As described above, when an ultrafine processed hole having a high aspect ratio with a diameter of about 100 nm is formed, it is difficult for an opaque liquid to penetrate into the processed hole due to the influence of surface tension or the like. When the opaque liquid does not sufficiently permeate the processing hole, and there is no opaque liquid on the bottom of the processing hole, the contact surface (interface) between the opaque liquid and the transparent substrate is not formed, so the hole processing is performed with interference light. become unable.

  Therefore, in the laser processing method of the present invention, the opaque liquid is effectively finely processed according to the progress of the processing of the microfabricated holes by setting at least the side of the transparent substrate that is in contact with the opaque liquid to a reduced pressure atmosphere. It is possible to infiltrate into the hole, so that an interface between the opaque liquid and the transparent substrate can be always formed, and the laser energy can be effectively concentrated by concentrating the laser energy in the vicinity of the interface that changes as the processing progresses. This is what makes processing a reality.

  Regarding the above-mentioned reduced pressure atmosphere, the degree of pressure reduction should be appropriately adjusted in consideration of the hole diameter of the finely processed hole and the degree of progress of the processed hole (depth of the processed hole), the vapor pressure of the opaque liquid, etc. Preferably, the inside of the container is reduced to a vacuum atmosphere as much as possible.

  Further, in a preferred embodiment of the laser processing method for a transparent substrate according to the present invention, a transparent liquid having substantially the same refractive index as that of the transparent substrate is brought into contact with one side surface of the glass substrate, and the transparent liquid is interposed therebetween. The other side surface of the transparent substrate is placed on one side surface of the glass substrate, and the interference light of the ultrashort pulse laser beam is irradiated from the other side surface of the glass substrate. is there.

  When the surface of the transparent substrate is viewed microscopically, various irregularities and in some cases scratches may exist. Due to the presence of these irregularities and scratches, the ultrashort pulse laser light incident on the transparent substrate may be scattered through these irregularities and the laser processing may not be possible.

  The present embodiment is for solving the above-mentioned problems. As a configuration for this purpose, a transparent liquid having substantially the same refractive index as that of the transparent substrate is brought into contact with the surface of the glass substrate, and this transparent liquid is used. Then, laser processing is performed in a posture in which a transparent substrate is placed on a glass substrate. Here, the substantially same refractive index includes both the same refractive index and an approximate refractive index.

  The transparent liquid enters the irregularities on the surface of the transparent substrate to make the surface a flat surface. Further, the transparent liquid has a refractive index comparable to that of the transparent substrate, so that the surface of the transparent substrate is flat. Regardless of the degree of the property, the scattering of the incident laser light can be effectively suppressed.

  Furthermore, in the method for producing an electrolyte membrane according to the present invention, a pore filling electrolyte membrane for a fuel cell is formed by filling each pore with an electrolyte resin in the porous transparent substrate produced by the laser processing method. To manufacture.

  The electrolyte membrane produced by this production method uses an electrolyte membrane such as a polymer electrolyte fuel cell (PEFC) or a direct methanol fuel cell (DMFC).

  The porous transparent substrate manufactured by the laser processing method of the present invention described above has a large number of processing holes having an ultrafine diameter and a high aspect ratio, and these processing holes are formed by the manufacturing method of the electrolyte membrane of the present invention. By filling the electrolyte resin, the proton resin bears the proton conductivity, and the mechanical strength of the film itself is borne by the transparent substrate, so that a high-quality electrolyte membrane can be manufactured.

  As can be understood from the above description, according to the laser processing method for a transparent substrate of the present invention, an ultrafine and high aspect ratio processed hole can be manufactured with high accuracy and efficiency with respect to the transparent substrate. Can do. Also, according to the method for producing an electrolyte membrane of the present invention, proton conductivity and mechanical strength can be obtained by filling a resin into the processing holes of the porous transparent substrate produced by this laser processing method to form an electrolyte membrane. It is possible to manufacture a high-quality electrolyte membrane for a fuel cell that is excellent in both of the above.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a laser processing apparatus for carrying out the laser processing method of the present invention, and FIG. 2 is an enlarged view of a vacuum vessel. FIG. 3 is an enlarged view of a part III in FIG. 2, and is a diagram illustrating a situation in which the processing progress progresses in the order of FIGS. FIG. 4A is a perspective view showing the manufactured porous transparent substrate, and FIG. 4B is a perspective view showing the manufactured pore filling electrolyte membrane. The embodiment of the laser processing method shown in the drawing is intended to form a microfabricated hole in a transparent substrate in order to form a pore filling electrolyte membrane for a fuel cell, but the microfabricated hole is formed. It goes without saying that the porous transparent substrate to be used is not limited to such applications.

  FIG. 1 shows an apparatus for forming a large number of microfabricated holes in a resin-made transparent substrate, and FIG. 2 is an enlarged view of a vacuum vessel. This laser processing apparatus 10 includes a laser oscillator 1 that emits femtosecond laser light as ultrashort pulse laser light, a diffraction grating 2 that receives the irradiated femtosecond laser light L1 and diffracts it into a plurality of light beams, Convex lenses 3 and 4 constituting a condensing optical system for causing the light beam L2 separated by the grating 2 to interfere with each other, and the interference light L3 formed by the cross interference of the light beam L2 and the transparent substrate W are accommodated. The vacuum vessel 8 is generally configured. An amplifier (not shown) may be provided between the laser oscillator 1 and the diffraction grating 2.

  The diffraction grating 2 can appropriately adjust the number of light beams divided depending on the type, and can also adjust the light beam diffraction angle and the like.

  Since the arrangement of the convex lenses 3 and 4, for example, the separation length thereof and the separation length from the convex lens 4 to the transparent base material W that is a work, determine the period of the interference wave of the interference light L 3. The number is adjusted as appropriate based on the number of fine holes to be formed by laser irradiation.

  Of the light beams divided by the convex lens 3, the zero-order light beam is blocked by the dump 9.

  The laser processing apparatus 10 performs micro processing on the sensor 6 including a CCD camera or the like that senses the level of the bottom surface of the processing hole according to the processing progress of the micro processing hole formed in the transparent substrate W, and further on the vacuum vessel 8 A servo motor 5 for controlling movement according to the processing progress of the hole and a feed screw mechanism 5 ′ for directly moving the vacuum vessel by this rotational drive are further provided, and the control device 7 receives a sensing signal from the sensor 6. The movement of the vacuum vessel 8 is controlled by rotationally driving the servo motor 5 according to the received signal. Further, the drive control of the laser oscillator 1 is also executed by the control device 7. For example, after a plurality of micro-machined holes forming a row by one shot of the laser are formed, the laser is similarly applied to the subsequent rows. Is shot. When the illustrated moving direction of the feed screw mechanism 5 ′ is the Z-axis direction, in addition to the illustrated servo motor 5 and feed screw mechanism 5 ′, the vacuum vessel 8 is placed in an XY plane perpendicular to the Z-axis direction. There may be provided an actuator for moving the inside. Furthermore, three-dimensional attitude control of the vacuum vessel 8 may be performed by synchronously controlling two or more of these actuators for XYZ direction control.

  As shown in FIG. 2, the vacuum container 8 is placed on a glass base 83 with a transparent container 81 whose inside can be visually recognized from the outside so that the opening is closed by the glass base 83. . The container 81 is provided with a vacuum suction port 82, through which a vacuum is drawn so that the inside of the container 81 has a reduced pressure atmosphere, preferably a vacuum atmosphere taking into account the vapor pressure of the opaque liquid (in the drawing). Arrow direction).

  A transparent liquid T, which is the same material as the transparent base W and has the same refractive index, is applied or dispersed on the side surface of the glass base 83 on the container 81 side, and the transparent base W is placed through the transparent liquid T. Is placed.

  On the side surface (upper surface in the figure) opposite to the side in contact with the transparent liquid T of the transparent substrate W, a light-absorbing opaque liquid F is applied or dispersed. As this opaque liquid F, a laser pigment such as rhodamine, a dye or a pigment is added to an organic solvent such as n-methyl-2-pyrrolidone or N, N-dimethylformamide or a high concentration alkaline solution such as caustic soda. Thus, a liquid having higher light absorption may be used.

  As shown in the drawing, the opaque liquid F permeates the bottom surface of the microfabricated hole P, and the microfabricated hole is processed by irradiating the interface with the bottom surface (opaque liquid F) with laser light. . Here, the vacuum in the container 81 is adjusted so as to gradually increase the degree of vacuum according to the processing progress of the processing hole, in addition to making the vacuum atmosphere at a stretch under the condition that the opaque liquid does not boil. Also good.

  In the laser processing method using the laser processing apparatus 10 shown in the drawing, the transparent substrate W is irradiated with the interference light L3 in a posture in which the inside of the container 81 is in a reduced pressure atmosphere, so that it is effective even if the processing hole has an ultrafine diameter. Thus, the opaque liquid can be permeated to the bottom of the hole in the processed hole, and the interface between the opaque liquid and the transparent substrate can be surely formed throughout the hole processing.

  Further, as shown in the figure, even when fine irregularities C exist on the surface of the transparent substrate W, the transparent liquid T fills the irregularities C, and therefore the interference light L3 is scattered by the irregularities C. The interference light can be focused on the target interface.

  FIG. 3 shows a situation in which laser processing is progressing in a posture where a strong light portion S is focused on the interface B between the opaque liquid F and the transparent base material W which penetrates the bottom surface of the fine processing hole P. FIG. FIG. 3A shows an initial stage of processing of the micro-processed hole P. As the process progresses, a micro-processed hole P having a high aspect ratio is formed as shown in FIG. 3B (in FIG. 3B, the process progress direction is indicated by an arrow Z). Shown). Further, when the processing proceeds, fine through holes are formed in the transparent substrate W. Note that an intensity graph relating to the position (X axis) and the light intensity (I) is shown below FIG.

  As described above, in the processing of the microfabricated hole P shown in FIG. 3, the level of the interface B is sensed at any time by the sensor 6, and this sensing data is transmitted to the control device 7 and based on the received data. The control device 7 drives the servo motor 5 to execute rotation control of the screw member constituting the feed screw mechanism 5 'and movement control of the nut and the vacuum vessel 8 according to this.

  According to the laser processing method described above, a plurality of microfabricated holes can be processed at once by using interference light of femtosecond laser light. Moreover, by accommodating a transparent base material in a vacuum vessel and executing laser processing, it is possible to accurately and efficiently form ultrafine and high aspect ratio processed holes. Furthermore, even when there are irregularities or scratches on the surface of the transparent substrate (this is often the case), it is possible to accurately focus the processing site without scattering the interference light by these irregularities or the like. it can.

  FIG. 4a shows a porous transparent substrate Wa manufactured by the laser processing method described above. In this porous transparent substrate Wa, a large number of fine through holes Pa penetrating between both wide side surfaces of the transparent substrate W are formed.

  By filling each fine through-hole Pa of the porous transparent substrate Wa with the electrolyte resin R, a pore filling electrolyte membrane Wb as shown in FIG. 4B is manufactured.

  The pore filling electrolyte membrane Wb is used as an electrolyte membrane for a polymer electrolyte fuel cell (PEFC) or a direct methanol fuel cell (DMFC), and is excellent in both proton conductivity and mechanical strength. The resulting electrolyte membrane.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is a block diagram of the laser processing apparatus for enforcing the laser processing method of this invention. It is the figure which expanded the vacuum vessel. It is the enlarged view of the III section of Drawing 2, and is a figure explaining the situation where processing progress is progressing in order of (a) and (b). (A) is the perspective view which showed the manufactured porous transparent base material, (b) is the perspective view which showed the manufactured pore filling electrolyte membrane.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser oscillator, 2 ... Diffraction grating, 3, 4 ... Convex lens, 5 ... Servo motor, 5 '... Feed screw mechanism, 6 ... Sensor, 7 ... Control apparatus, 8 ... Vacuum container, 81 ... Container, 82 ... Vacuum Suction port, 83 ... glass substrate, 9 ... dump, 10 ... laser processing device, W ... transparent substrate, Wa ... porous transparent substrate, Wb ... pore filling electrolyte membrane, F ... opaque liquid, T ... transparent liquid , P ... finely processed hole, Pa ... fine through-hole, R ... electrolyte resin, B ... interface, S ... strong light part, C ... unevenness

Claims (6)

One side of the light-transmitting transparent substrate is in a reduced pressure atmosphere, and the one side is in contact with a light-absorbing opaque liquid,
By irradiating interference light of ultrashort pulse laser light from the other side surface of the transparent base material, transmitting the transparent base material, and concentrating the laser energy of the interference light near the interface between the transparent base material and the opaque liquid A laser processing method for a transparent substrate, wherein finely processed holes are formed in the transparent substrate.   A transparent liquid having substantially the same refractive index as that of the transparent base is brought into contact with one side of the glass base, and the other side of the transparent base is placed on one side of the glass base through the transparent liquid. 2. The laser processing method for a transparent substrate according to claim 1, wherein interference light of an ultrashort pulse laser beam is irradiated from the other side of the glass substrate.   The laser processing method for a transparent substrate according to claim 1, wherein the ultrashort pulse laser beam is a femtosecond laser beam.   The laser processing method of the transparent base material in any one of Claims 1-3 in which the said opaque liquid consists of any one of an organic solvent and a high concentration alkaline solution.   The laser processing method for a transparent substrate according to any one of claims 1 to 4, wherein any one of a dye and a pigment is added to the opaque liquid.   A porous transparent substrate is formed by the laser processing method according to claim 1, and then a pore filling electrolyte membrane for a fuel cell is manufactured by filling each hole with an electrolyte resin. The manufacturing method of an electrolyte membrane.

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