JP4855768B2 - Manufacturing method of mold for fine pattern molding - Google Patents

Description

The present invention relates microlens and a cylindrical lens, a manufacturing method of a fine pattern forming mold for molding a product on which a fine pattern is formed like a prism lens.

  In recent years, products on which fine patterns are formed are used in various fields. A typical field is an image display device. In general, an image display device such as a liquid crystal display (LCD) that requires a surface light source element using a light emitter such as a fluorescent tube, LED (light emitting diode), organic EL (electroluminescence), and inorganic EL as a light source is polarized. The light utilization efficiency is greatly reduced by the influence of the plate, the aperture ratio of the liquid crystal cell, the color filter, and the reflection on the display surface. In order to improve the light utilization efficiency, various fine patterns may be used. Examples of the fine pattern include providing a directivity to the emitted light by adding a prism lens sheet to an aperture ratio improving element or a surface light source element of a liquid crystal cell using a microlens. In addition, the use of this fine pattern is spreading not only to image display devices but also to bio and medical applications.

  On the other hand, conventionally, as a method for producing a fine pattern, there are a method of cutting and polishing a material such as glass or plastic, a method of forming with a mold having a negative pattern of the fine pattern and molding with a thermoplastic resin, etc. It has been adopted. In particular, the method of molding with a thermoplastic resin using a mold can be said to be a method suitable for mass production because the molding cycle is very fast.

  The mold manufacturing method is largely divided into (1) a method in which a metal plate is directly cut and polished, and (2) a method in which a desired fine pattern is formed in advance and then a negative pattern of the fine pattern is produced by electroforming. Separated. In (1), since the metal plate is directly cut, the fine pattern depends on the shape of the cutting tool, and it is difficult to form an arbitrary fine pattern. On the other hand, the following methods and the like have been proposed and put into practical use for forming the fine pattern (2) in advance.

(2-1) Registry flow method: A method of producing a desired fine pattern by uniformly applying a resist on a substrate, patterning the resist by exposure / development using a photomask, and heating the resist to flow ( For example, Non-Patent Document 1).
(2-2) Laser direct drawing method: A method of producing a fine pattern by scanning and exposing an ultraviolet laser on a resist (for example, Patent Document 1).

  However, in the method (2-1), it is easy to produce a plurality of fine patterns having the same shape. However, since the fine pattern is formed using the flow phenomenon (surface tension) of the resist, It is extremely difficult to produce a plurality of fine patterns having different shapes, particularly shapes including curved surfaces. Further, in the method (2-2), it is possible to produce a plurality of fine patterns having asymmetric shapes or irregular shapes. However, a general resist material has a height of 5 μm or more because the depth of focus is shallow. It is difficult to precisely produce a certain fine pattern.

  That is, it is difficult to produce a plurality of fine patterns having a curved portion with a height of 5 μm or more by a conventional method of producing a fine pattern with a mold.

  On the other hand, recently, as a method for forming a fine pattern, three-dimensional microfabrication of a photocurable resin by two-photon excitation has been proposed (for example, Patent Documents 2 and 3). The three-dimensional microfabrication uses two low-energy near-infrared pulse lasers as the light source, and two polymerization initiators in the photocurable resin are formed only in the focal region where the photon density becomes very high by condensing the light source. It is excited by absorbing photons, and polymerization of the photocurable resin is started. For this reason, a very high three-dimensional resolution can be realized. Here, the three-dimensional resolution depends on the power of the near-infrared pulse laser, the numerical aperture NA of the condenser lens, etc., and by optimizing each parameter, the line width can be reduced to 0.1 μm or less, The depth can be 0.5 μm or less. Further, by controlling the position of the focal point, it becomes possible to precisely produce a finely shaped object having a height of 5 μm or more in the photocurable resin. On the other hand, normal stereolithography is one-photon excitation, and high-energy ultraviolet light or the like is used as a light source. Therefore, polymerization is started even in a region other than the focal point of the light source, so the resolution is low. Moreover, when producing the fine modeling thing which has a height of 5 micrometers or more, photocurable resin must be laminated | stacked, Therefore There also exists a problem which a level | step difference will be made. Therefore, when producing a fine pattern by two-photon excitation and one-photon excitation, a two-photon excitation can provide a finely shaped object with a higher three-dimensional resolution. In particular, three-dimensional microfabrication by two-photon excitation is more suitable for producing an optical pattern that requires a three-dimensional resolution on the order of visible light wavelength.

As described above, three-dimensional microfabrication of photo-curing resin by two-photon excitation is a method with high three-dimensional resolution, but it has a very low probability of occurrence of two-photon absorption and is difficult to occur. There is a problem that it takes a long time. Although Patent Document 3 proposes the production of a micromachine using the three-dimensional microfabrication, it is considered difficult to manufacture in large quantities due to the problem of processing time. There is also a problem that the product on which the fine pattern is formed is limited to the photocurable resin material.
Applied Optics, vol27, No.7,1281-1284 (1988) JP-A-5-217831 JP 2001-158050 A Japanese Patent Laid-Open No. 2003-1599

The present invention makes it possible to form a desired fine pattern such as an asymmetric shape or an irregular shape, and to shorten the entire manufacturing time when a product on which the fine pattern is formed is mass-produced. It aims at providing the manufacturing method of this metal mold | die for fine pattern shaping | molding.

  The present inventors have found that the three-dimensional microfabrication is applied to mass production of a product on which a fine pattern is formed by taking advantage of the high three-dimensional resolution of the three-dimensional microfabrication. In other words, intensive studies were conducted to solve the problem that the production time would become longer if a product with a fine pattern formed by simply three-dimensional microfabrication was mass-produced. When a product is molded with a thermoplastic resin using a fine pattern molding die manufactured using this as a prototype, the molding cycle can be accelerated and mass-produced. Thus, the present invention has been completed based on the knowledge that the entire manufacturing time can be shortened by molding products such as optical components and light control plates for surface light source elements using the mold.

That is, in the method for manufacturing a fine pattern molding die according to the present invention, the focusing position of the pulse laser is controlled, and only the photocurable resin at the position where the pulse laser is focused and irradiated is selectively photopolymerized. Then, a three-dimensional microfabrication of a photo-curable resin by two-photon excitation is used to produce a fine shaped object on which a desired fine pattern is formed, and the fine pattern molding die is formed using the produced fine shaped article as a prototype. It is characterized by manufacturing.
Here, the original mold refers to an original mold for producing a metal mold that is a metal mold for mass-producing products.

  According to this configuration, a finely shaped article is produced by three-dimensional microfabrication, and the fine pattern forming mold is manufactured using the finely shaped article as a prototype, so that a desired curved portion having a height of 5 μm or more is desired. A fine pattern can be formed by the mold, and when a product on which the fine pattern is formed is mass-produced, a product is manufactured by using a mold with a micro-modeled object that takes a long time to manufacture. This makes it possible to shorten the entire manufacturing time and diversify the product materials as compared to mass production directly by conventional three-dimensional microfabrication.

  Preferably, the mold for forming a fine pattern is manufactured by electroforming using a finely shaped object produced by the three-dimensional microfabrication as a prototype.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 5 shows a schematic configuration diagram of a three-dimensional microfabrication apparatus of a photocurable resin by two-photon excitation, which produces a finely shaped object on which a desired fine pattern is formed as a prototype of a fine pattern molding die. .

  This apparatus uses a near-infrared pulse laser 100 such as a titanium sapphire laser, and transmits and reflects various optical systems such as a shutter 111, an ND filter 112, a beam expander 113, a relay lens 114, and a galvano mirror 121 to produce a near-infrared laser. An infrared pulse laser is incident on the lens 122. It should be noted that a plurality of the above optical systems can be used as necessary, and can be omitted if unnecessary. The near-infrared pulse laser incident on the lens 122 is condensed, and the photocurable resin 140 can be polymerized only at the condensing position. Further, the glass 130 coated with the photo-curable resin 140 is fixed to the Z-axis stage 131, the Z-axis stage is moved up and down, and the laser is scanned in the XY plane using the galvano mirror 121. By doing so, a desired finely shaped object can be produced. Since the photo-curable resin 140 is transparent to the near-infrared pulse laser, a finely shaped article having a height of 5 μm or more can be produced. Although not shown here, a stage for fixing the glass 130 is an XYZ stage, so that a desired finely shaped object can be produced without using the galvanometer mirror 121. In the above description, the case of a near-infrared laser is taken as an example, but a visible light laser may be used as long as the photocurable resin is not cured by normal irradiation.

  The photocurable resin used for three-dimensional microfabrication is not particularly limited. However, in order to perform two-photon excitation polymerization efficiently, a dye having a large two-photon absorption cross-section must be added to a resin composition containing various acrylate monomers and epoxy monomers and corresponding photopolymerization initiators. Is preferred. Examples of the dye having a large two-photon absorption cross section include commercially available rhodamine B, eosin Y, and bisstyrylbenzene dyes.

  In addition, in order to obtain a finely shaped object that is a prototype efficiently by three-dimensional microfabrication, it is also possible to simultaneously produce a plurality of minutely shaped objects. It may be divided into a plurality of lasers using a hole array, or only the outer shell of a desired finely shaped object may be cured, and an uncured photocurable resin may be cured with ultraviolet light after development processing described later.

  Since the uncured photo-curing resin is attached to the produced microfabricated product, it is necessary to perform development processing with a developer. The developer may be any developer that can wash away the uncured photocurable resin without eroding the cured photocurable resin.

  FIG. 1 is a side view showing a method of manufacturing a fine pattern molding die according to an embodiment of the present invention. A method for manufacturing a mold for forming a micropattern using the microfabricated product 20 obtained by three-dimensional microfabrication of a photocurable resin by two-photon excitation as described above is not particularly limited, but here, as an example, an electroforming process is performed. A method of manufacturing a mold according to will be described.

  First, the micro model 20 that is the prototype is immersed in the electrolytic cell 21 and disposed on the cathode 22, and a metal such as gold, silver, copper, or nickel is disposed on the anode 23. By applying a direct current in this state, metal ions are eluted from the anode 23. The eluted metal ions are deposited as a metal on the finely shaped object 20 arranged on the cathode 22, whereby the fine pattern forming mold 24 can be manufactured.

  When a product is molded using the fine pattern molding die 24, materials that can be used for molding include thermoplastic resins and photo-curable resins, and products manufactured by conventional three-dimensional microfabrication. In contrast, the present invention is limited to the photo-curable resin, the present invention allows a wide selection of product materials. Examples of the molding method include injection molding, extrusion molding, press molding, and photopolymerization molding with a photocurable resin. These molding materials and molding methods are merely examples, and are not limited thereto.

  By using the fine pattern molding die of the present invention and the molding material and molding method described above, various optical components can be molded. For example, if the fine pattern is a cylindrical lens, a lenticular lens sheet, if it is a microlens array, a microlens array sheet, if it is a prism lens, a prism lens sheet, if it is a Fresnel lens, a Fresnel lens sheet can be obtained. It is not limited.

  In addition, application to the light control plate for the surface light source element shown in FIG. 2 is also possible (for example, see US Pat. No. 5,396,350). A surface light source element (backlight) 30 that emits light in a planar shape is manufactured by bonding a light control plate 32 to a light guide plate 31. For example, a plurality of microlens arrays 33 having a substantially hemispherical curved surface with a height of 20 μm are arranged in parallel on the light control plate 32, and the light guide plate 31 and the microlens array are interposed via an adhesive 34. 33 is adhered. When the microlens array 33 is composed of only the curved surface portion 41 as shown in FIG. 3, the adhesive portion 42 must be controlled by optimizing the bonding pressure, the elastic modulus of the adhesive, etc. Is difficult to paste. On the other hand, if the cross-sectional shape of the microlens array 33 has a flat portion 51 and a curved surface portion 52 as shown in FIG. 4, the microlens array 33 can be stably bonded to the light guide plate 31.

  In the conventional registry flow method described above, since the surface tension of the resist is used, it is very difficult to produce a micro-patterned product having the curved surface portion and the flat portion shown in FIG. In the three-dimensional microfabrication of the photocurable resin by excitation, it is possible to easily produce a finely shaped object having a desired fine pattern having a curved surface portion having a height of 5 μm or more. Then, a fine pattern molding die is manufactured using this as a prototype, and a product of a light control plate for a surface light source element is molded using this die. By using the manufactured fine pattern molding die, the light control plate for the surface light source element in which the fine pattern is formed is easily produced, and when the surface light source element light control plate is mass-produced, The entire manufacturing time can be shortened, and not only a photocurable resin but also a thermoplastic resin can be used widely as a product material.

Example 1
First, a photocurable resin was prepared as a prototype material for a fine pattern molding die. As an acrylate monomer, pentaerythritol triacrylate (M-309: manufactured by Toagosei Co., Ltd.) and isocyanuric acid ethylene oxide-modified di-triacrylate (M-313: manufactured by Toagosei Co., Ltd.) were mixed 35 parts by weight, and Rhodamine B 0.1 part by weight (manufactured by Kanto Chemical Co., Inc.) was added. Next, 29.9 parts by weight of a poly (styrene-acrylonitrile) copolymer (manufactured by Kanto Chemical Co., Inc.) was added as a binder, and the viscosity was adjusted with 1,4-dioxane as a diluent solvent.

  Next, the prepared photocurable resin was applied on a slide glass with a thickness of 100 μm. In addition, in order to improve the adhesiveness of photocurable resin and a slide glass, the slide glass was processed in advance using 3-aminopropyl triethoxysilane (made by Kanto Chemical Co., Inc.). Furthermore, a photocurable resin film was formed by completely volatilizing 1,4-dioxane as a diluting solvent.

  The slide glass on which the photocurable resin film is formed is installed in the three-dimensional microfabrication apparatus shown in FIG. 5, and a near-infrared pulse laser (Tsunami: manufactured by Spectra Physics Co., Ltd.) is focused and irradiated. The laser was scanned so that the cured portion was a cylindrical lens having a kamaboko height of 5 μm. Finally, the glass substrate was immersed in a solvent of N, N-dimethylformamide (manufactured by Kanto Chemical Co., Inc.), and the uncured photocurable resin was developed and removed to obtain a prototype of a cylindrical lens.

  Next, the mold of the cylindrical lens obtained by the three-dimensional microfabrication was electroformed to produce a nickel mold. A large number of cylindrical lens array sheets could be replicated by photopolymerization molding on a polyethylene terephthalate film using the mold.

(Example 2)
In the same manner as in Example 1, after applying a photocurable resin on a slide glass, it was installed in the three-dimensional microfabrication apparatus in FIG. 5 and focused with a near infrared pulse laser (Tsunami: manufactured by Spectra Physics Co., Ltd.) Irradiated and scanned with a laser so that the cured portion of the photo-curable resin was a microlens array having a plurality of substantially hemispherical shapes with a height of 20 μm and a width of 25 μm. Finally, the glass substrate was dipped in a solvent of N, N-dimethylformamide (manufactured by Kanto Chemical Co., Inc.), and the uncured photocurable resin was developed and removed to obtain a prototype of a microlens array. .

  Next, the original mold of the microlens array obtained by the three-dimensional microfabrication was subjected to an electroforming process to produce a nickel mold. A light control plate on which a microlens array was formed could be obtained by photopolymerization molding on a polyethylene terephthalate film using the mold. The top of the microlens array in the light control plate and a 0.8 mmt light guide plate made of polymethylmethacrylate (Paraglass: manufactured by Kuraray Co., Ltd.) may be bonded together to form a surface light source element. did it. Furthermore, when an LED (NACW215: manufactured by Nichia Corporation) was installed on the side surface of the surface light source element and a current of 20 mA was applied to the LED, uniform light emission from the surface light source element could be confirmed.

It is a side view which shows the manufacturing method of the metal mold | die for a fine pattern shaping | molding concerning one Embodiment of this invention. It is a perspective view which shows a surface light source element. It is a side view which shows an example of the cross-sectional shape of a micro lens array. It is a side view which shows the other example of the cross-sectional shape of a micro lens array. It is a schematic block diagram of the three-dimensional microfabrication apparatus of the photocurable resin by two photon excitation.

Explanation of symbols

20: Microfabricated object 21: Electrolytic cell 22: Cathode 23: Anode 24: Mold for fine pattern molding 30: Surface light source element 31: Light guide plate 32: Light control plate 33: Micro lens array 34: Adhesive 41: Curved portion 42 of microlens array: Adhesive portion 51: Flat portion 52 of microlens array 52: Curved portion of microlens array 100: Near infrared pulse laser 111: Shutter 112: ND filter 113: Beam expander 114: Relay lens 121 : Galvano mirror 122: Lens 130: Glass 131: Z-axis stage 140: Photocurable resin

Claims (2)

By controlling the focusing position of the pulse laser and selectively photopolymerizing only the photocurable resin at the position where the pulse laser is focused and irradiated, by three-dimensional microfabrication of the photocurable resin by two-photon excitation, A method for producing a fine pattern forming mold, comprising: producing a fine shaped article on which a desired fine pattern is formed, and producing the fine pattern forming mold using the produced fine shaped article as a prototype. The method for producing a fine pattern molding die according to claim 1, wherein the fine pattern molding die is produced by electroforming using a finely shaped article produced by the three-dimensional microfabrication as a prototype.

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