JP2005208512A - Manufacturing method of optical element and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of optical element which is capable of easily releasing an optical element provided with fine irregularities without using a releasing agent of degrading performances such as the transmissivity, refractive index and light transmission loss of the optical element and hardly causes scratch and fouling on the surface of die. <P>SOLUTION: A metal film 6 which does not diffuse into die material at a molding temperature is formed on the surface of the die 5 having fine irregularities and a fine structure 7 is formed by filling a molding resin 2 into a cavity having the die 5 on one surface thereof and curing the same. Further upon the die opening, the metal film 6 is peeled from the surface of the die 5, the fine structure 7 in such a state that the metal film 6 is adhered on the surface is released and, thereafter, is immersed to a solvent which does not dissolve the resin and can dissolve only a metal film 6 layer and, thereby, the metal film 6 is removed from the surface of the fine structure 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

Translated fromJapanese

本発明は、型を用いた樹脂成形による光学素子の製造方法及び光学素子に関する。光学素子としては、ポリマ型の光導波路、レンズ、フィルター、回折格子、プリズム、光学記録媒体などがある。  The present invention relates to a method for manufacturing an optical element by resin molding using a mold and the optical element. Examples of the optical element include a polymer type optical waveguide, a lens, a filter, a diffraction grating, a prism, and an optical recording medium.

従来、この種の光学素子の製造においては、成形金型と成形樹脂との密着による離型性に問題があり、その原因は次の二つが考えられる。（１）金型金属と成形樹脂が分子間力により密着性を有すること。（２）金型表面に有機物や酸素が付着汚染することで、成形樹脂との密着層の働きをすること。  Conventionally, in the production of this type of optical element, there is a problem in the releasability due to the close contact between the molding die and the molding resin, and the following two causes are considered. (1) The mold metal and the molding resin have adhesion due to intermolecular force. (2) To act as an adhesion layer with the molding resin by organic substances and oxygen adhering to and contaminating the mold surface.

（１）の原因に対しては下記のような対策がとられている。
（１−１）シリコンやフッ素化合物からなる離型剤を金型表面へ塗布すること（汎用技術）、
（１−２）成形樹脂中へ微量の離型剤を含有させること（特許文献１参照）
（１−３）金型表面へ成形樹脂と密着性の弱いＣｏ、Ｔｉなどの金属又は合金、若しくは窒化物などを蒸着やスパッタリングや湿式メッキで被覆することThe following measures are taken for the cause of (1).
(1-1) Applying a mold release agent made of silicon or a fluorine compound to the mold surface (general-purpose technology),
(1-2) Inclusion of a small amount of release agent in the molding resin (see Patent Document 1)
(1-3) Coating the mold surface with a metal or alloy such as Co or Ti having weak adhesion to the molding resin or nitride, or nitride by vapor deposition, sputtering or wet plating.

（２）の原因に対しては下記のような対策が取られている。
（２−１）金型表面を窒素プラズマ処理する方法（特許文献２参照）
（２−２）金型表面に金の被覆膜を形成する方法（特許文献３参照）
（２−３）金型表面を酸素アッシング処理後、不活性ガスプラズマ照射する方法（特許文献４参照）The following measures are taken for the cause of (2).
(2-1) Method of Nitrogen Plasma Treatment of Mold Surface (see Patent Document 2)
(2-2) Method of forming a gold coating film on the mold surface (see Patent Document 3)
(2-3) Method of irradiating inert gas plasma after oxygen ashing on mold surface (see Patent Document 4)

しかしながら、上記対策だけでは次のような問題がある。
上記（１−１）の離型剤を用いる場合、光学素子の透過率や屈折率や光伝送損失などの性能を落とすだけでなく、例えば光学素子上に形成する層の密着性をも低下させる。
上記（１−２）（１−３）、及び（２−１）から（２−３）の対策では、高温の成形条件で繰り返し使用した場合に、成形樹脂成分により汚染されるため、密着による離型性の問題が生じる。このため、各処理を定期的に行う必要がある。しかし、この処理により型表面の粗さが大きくなり、光学素子の上記性能が劣化することが問題となる。このため、金型の寿命が短くなる。
特開平１０−３０８０４０号公報特公平３−３９３４０号公報特公平３−３５４号公報特許第２７５３３８８号However, the above measures alone have the following problems.
When the release agent (1-1) is used, not only the performance of the optical element such as transmittance, refractive index, and optical transmission loss is deteriorated, but also, for example, the adhesion of a layer formed on the optical element is also reduced. .
In the measures (1-2), (1-3), and (2-1) to (2-3), when repeatedly used under high-temperature molding conditions, the resin is contaminated with molded resin components. A problem of releasability occurs. For this reason, it is necessary to perform each process regularly. However, this process increases the roughness of the mold surface and causes a problem that the performance of the optical element is deteriorated. For this reason, the lifetime of a metal mold | die becomes short.
JP-A-10-308040 Japanese Patent Publication No. 3-39340 Japanese Patent Publication No. 3-354 Japanese Patent No. 2753388

本発明は、上記の問題を解決するためになされたものであり、光学素子の透過率や屈折率や光伝送損失などの性能を落とす離型剤を用いることなく、微細な凹凸を備えた光学素子を容易に離型することができ、また、型表面に傷や汚れが付着し難く、型寿命が向上する光学素子の製造方法と光学素子を提供することを目的とする。  The present invention has been made in order to solve the above problems, and an optical device having fine irregularities without using a release agent that degrades the transmittance, refractive index, optical transmission loss and the like of the optical element. An object of the present invention is to provide an optical element manufacturing method and an optical element in which the element can be easily released, scratches and dirt are difficult to adhere to the mold surface, and the mold life is improved.

上記目的を達成するために請求項１の発明は、微細凹凸を持つ型表面に、型材質に対して成形温度下で拡散しない金属膜を形成する金属膜形成工程と、前記微細凹凸を持つ型を少なくとも一面に持つキャビティ内に樹脂を充填・硬化させて、微細構造体を形成する光学素子成形工程と、前記型表面より前記金属膜を剥離させ、該金属膜が微細構造体表面に付着した状態で型開きを行う光学素子離型工程と、前記樹脂を溶解せず金属膜層のみを溶解可能な溶剤に前記微細構造体を浸すことで、微細構造体表面より金属膜を除去する金属膜除去工程と、を備えた光学素子の製造方法である。  In order to achieve the above object, the invention ofclaim 1 includes a metal film forming step of forming a metal film that does not diffuse at a molding temperature on a mold surface having a fine unevenness, and a mold having the fine unevenness. An optical element molding step for filling and curing a resin in a cavity having at least one surface to form a fine structure, and peeling off the metal film from the mold surface, and the metal film adhered to the surface of the fine structure An optical element releasing step for opening the mold in a state, and a metal film that removes the metal film from the surface of the microstructure by immersing the microstructure in a solvent capable of dissolving only the metal film layer without dissolving the resin And a removing step.

請求項２の発明は、請求項１記載の光学素子の製造方法において、金属膜形成工程において、金属膜として銅、ニッケル、クロム、コバルト又はそれらの化合物を形成し、金属膜除去工程において、溶剤として過酸化水素、過マンガン酸塩、重クロム酸塩を用いるものである。  According to a second aspect of the present invention, in the optical element manufacturing method according to the first aspect, in the metal film forming step, copper, nickel, chromium, cobalt or a compound thereof is formed as the metal film, and in the metal film removing step, the solvent Hydrogen peroxide, permanganate and dichromate are used as

請求項３の発明は、請求項１記載の光学素子の製造方法において、金属膜形成工程において、金属膜として型材よりも線膨張率の小さい金属を用い、光学素子成形工程と光学素子離型工程の間に、型の温度を成形温度から低下させる型冷却工程を備えたものである。  According to a third aspect of the present invention, in the optical element manufacturing method according to the first aspect, in the metal film forming step, a metal having a smaller linear expansion coefficient than the mold material is used as the metal film, and the optical element molding step and the optical element release step In the meantime, a mold cooling step for lowering the mold temperature from the molding temperature is provided.

請求項４の発明は、請求項１乃至請求項３のいずれかに記載の製造方法を用いて製造された光学素子である。  A fourth aspect of the present invention is an optical element manufactured by using the manufacturing method according to any one of the first to third aspects.

請求項１の発明によれば、金属膜を微細構造体表面に付着した状態で型開きを行うので、屈折率等に影響を及ぼす離型材を用いることなく、微細な凹凸を備えた光学素子を容易に離型可能となる。また、離型材を用いて行う成形方法に較べて、型と金属膜間できれいに剥がれるので、型表面に傷・汚れが付着し難くなり、型寿命が向上する。  According to the invention ofclaim 1, since the mold opening is performed in a state where the metal film is adhered to the surface of the fine structure, an optical element having fine irregularities can be obtained without using a release material that affects the refractive index and the like. It can be easily released. Further, compared to a molding method using a mold release material, the mold and the metal film are peeled cleanly, so that scratches and dirt are less likely to adhere to the mold surface, and the mold life is improved.

請求項２の発明によれば、金属膜及び溶剤を用いることにより、処理薬品濃度、温度、時間により容易にピール強度を制御できるため、金属層の除去が容易に可能である。  According to the invention ofclaim 2, by using the metal film and the solvent, the peel strength can be easily controlled by the treatment chemical concentration, temperature, and time, so that the metal layer can be easily removed.

請求項３の発明によれば、光学素子の離型工程時に型材と金属膜との間の熱膨張の差により剥離し易くなっているので、光学素子の離型工程時の欠けが防止できる。  According to the invention ofclaim 3, since it is easy to peel off due to the difference in thermal expansion between the mold material and the metal film during the mold release process of the optical element, chipping during the mold release process of the optical element can be prevented.

請求項４の発明によれば、離型時の傷・欠けが少ない凹凸形状を形成できるので、性能劣化を防止できる。  According to the fourth aspect of the present invention, it is possible to form a concavo-convex shape with few scratches / chips at the time of mold release, thereby preventing performance deterioration.

本発明の実施形態について図面を参照して説明する。図１は、本発明方法により製造される光学素子の一例を示す。この光学素子１は、基材である光透過性の成形樹脂（熱可塑性樹脂）２に微細な凹凸が転写されることで形成される光導波路基板（クラッド）であって、ここでは光導波路３は光分岐のスプリッタ構造を持つ。光導波路３をなす凹部の幅寸法は、約１０μｍ前後又はそれ以下とされ、この凹部に屈折率がクラッドよりも高いコア材（図示なし）が装入され、基板上はカバークラッドで覆われる。  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an optical element manufactured by the method of the present invention. Theoptical element 1 is an optical waveguide substrate (clad) formed by transferring fine irregularities to a light-transmitting molding resin (thermoplastic resin) 2 as a base material. Has a splitter structure with optical branching. The width of the recess forming theoptical waveguide 3 is about 10 μm or less, and a core material (not shown) having a higher refractive index than that of the cladding is inserted into the recess, and the substrate is covered with a cover cladding.

（実施例１）
図２は、光学素子、詳細には、その基材である光導波路基板の製造方法の工程を概念的に示しており、以下、時系列の番号順に説明する。(Example 1)
FIG. 2 conceptually shows the steps of the manufacturing method of the optical element, specifically, the optical waveguide substrate that is the base material, and will be described below in the order of time-series numbers.

（１）先ず、上述した光導波路基板に光導波路用の微細な凹凸を成形するための凹凸部５ａ（微細凹凸）を持つ型５を加工する（型加工工程）。ここに、型５は、材質ＳＵＳ３０４の金属へ切削加工方法により光学素子となる形状を形成する。(1) First, themold 5 having theuneven portion 5a (fine unevenness) for forming the fine unevenness for the optical waveguide on the optical waveguide substrate described above is processed (die processing step). Here, themold 5 forms a shape to be an optical element by cutting a metal of material SUS304 by a cutting method.

（２）型５の表面に、型５の材質に対して成形温度下で拡散しない金属膜６を厚さ０．０５〜１．０μｍで形成する（金属膜形成工程）。ここに、金属膜６は、厚さ０．０５〜１．０μｍであればよく、本例では、厚さ０．２μｍの銅金属膜を電気メッキ法により形成した。電気銅メッキは、液組成が、硫酸銅五水和：８０ｇ／Ｌ、硫酸：１８０ｇ／Ｌ、塩素イオン：６０ｍＬ／Ｌ、光沢剤：微量とし、液温度：２３℃、電流密度：１Ａ／ｄｍ^２、メッキ時間：６０秒とした。
なお、切削加工した材質ＳＵＳ３０４の表面には、大気中で不活性被膜が形成されているため、同材質と金属膜６とは密着していない。このため、金属膜６上にセロハンテープを貼り付け剥離するテープテスト（ピール強度試験）を行ったところ、金属膜６と型５の界面で容易に剥離できた。金属膜６の形成方法としては、上記電気メッキ法の他に、無電解メッキ法、スパッタリング法、蒸着法がある。そして、生産性の点で電気メッキ法が最も優れている。(2) On the surface of themold 5, ametal film 6 that does not diffuse with respect to the material of themold 5 at a molding temperature is formed with a thickness of 0.05 to 1.0 μm (metal film forming step). Here, themetal film 6 may have a thickness of 0.05 to 1.0 μm, and in this example, a copper metal film having a thickness of 0.2 μm was formed by electroplating. The electrolytic copper plating has a liquid composition of copper sulfate pentahydrate: 80 g / L, sulfuric acid: 180 g / L, chlorine ion: 60 mL / L, brightener: trace amount, liquid temperature: 23 ° C., current density: 1 A / dm^2. Plating time: 60 seconds.
In addition, since the inert film is formed in the air | atmosphere on the surface of the cut material SUS304, the same material and themetal film 6 are not closely_contact | adhered. For this reason, when a tape test (peel strength test) for attaching and peeling the cellophane tape on themetal film 6 was performed, it was easily peeled off at the interface between themetal film 6 and themold 5. As a method for forming themetal film 6, there are an electroless plating method, a sputtering method, and a vapor deposition method in addition to the electroplating method. The electroplating method is most excellent in terms of productivity.

（３）金属膜６を被覆した型５と図示していない型とにより区画したキャビティ内に温度２３０℃の成形樹脂２を充填し、その後、７０℃まで冷却して硬化させて、微細構造体を形成する（光学素子成形工程）。成形樹脂２としては、例えば、熱可塑性アクリル樹脂を用いる。(3) Amold resin 2 having a temperature of 230 ° C. is filled in a cavity defined by amold 5 coated with ametal film 6 and a mold (not shown), and then cooled to 70 ° C. and cured to obtain a fine structure. Is formed (optical element molding step). As themolding resin 2, for example, a thermoplastic acrylic resin is used.

（４）上記による硬化後、型開きを行うことで、前記金属膜６を型５の表面より剥離させ、成形樹脂２の表面に金属膜６が付着した状態の微細構造体７を離型する（光学素子離型工程）。ここに、金属膜６は型５との界面で容易に剥離でき、金属膜６は光学素子となる樹脂側に密着する。型開き温度：７０℃、型開き速度：５ｍｍ／秒とした。
量産を行う場合、型５は、上記（２）の金属膜形成から（４）の型開きの工程を繰り返す。この場合、型を二台または複数用いて連続して成形することもできる。また、（２）の金属膜形成、（３）の成形、及び（４）の型開きを、後述する図３に示すように、同一装置内で処理することも可能である。型開きの時の温度と開き速度は特に限定しないが、温度が高い場合には、成形樹脂２が柔らかいために、光学素子の形状が崩れやすく、また、型開き速度が速い場合には、金属膜６が型５側に付着し、成形樹脂２の表面層が破壊される。(4) After the curing as described above, themetal film 6 is peeled off from the surface of themold 5 by performing mold opening, and themicrostructure 7 having themetal film 6 attached to the surface of themolding resin 2 is released. (Optical element release step). Here, themetal film 6 can be easily peeled off at the interface with themold 5, and themetal film 6 is in close contact with the resin side serving as an optical element. Mold opening temperature: 70 ° C., mold opening speed: 5 mm / second.
In the case of mass production, themold 5 repeats the steps from the metal film formation (2) to the mold opening (4). In this case, two or more molds can be used for continuous molding. Further, the metal film formation (2), the molding (3), and the mold opening (4) can be processed in the same apparatus as shown in FIG. The temperature and opening speed at the time of mold opening are not particularly limited. However, when the temperature is high, themolding resin 2 is soft, so that the shape of the optical element tends to collapse, and when the mold opening speed is high, metal Thefilm 6 adheres to themold 5 side, and the surface layer of themolding resin 2 is destroyed.

（５）前記成形樹脂２を溶解せず金属膜６のみを溶解可能な溶剤に浸漬することで、金属膜６を微細構造体７の表面より溶解除去する（金属膜除去工程）。金属膜６を除去した成形樹脂２からなる微細構造体７’は光学素子のもとになる光導波路基板となる。ここに、溶剤は、２０％過硫酸ナトリウム水溶液を用いた。目視で観察される除去時間は２０秒であったが、微量の残渣物を除去するために、４０秒間浸漬させた。本実施例では、１０００ショット成形した後も、型に傷や汚れの付着もなく容易に離型が可能であった。また、成形した光学素子も形状の崩れや光学特性の劣化が認められなかった。(5) Themetal film 6 is dissolved and removed from the surface of thefine structure 7 by immersing it in a solvent capable of dissolving only themetal film 6 without dissolving the molding resin 2 (metal film removal step). Thefine structure 7 ′ made of themolding resin 2 from which themetal film 6 has been removed becomes an optical waveguide substrate that is the basis of the optical element. Here, 20% sodium persulfate aqueous solution was used as the solvent. The removal time visually observed was 20 seconds, but was immersed for 40 seconds in order to remove a trace amount of residue. In this example, even after 1000 shot molding, the mold could be easily released without any scratches or dirt. Also, the molded optical element was not deformed in shape or deteriorated in optical characteristics.

本実施例によれば、離型材を用いることなく、微細な凹凸を備えた光学素子を容易に離型可能であるので、光学素子の屈折率等に影響を及ぼすことがなくなり、また、型と金属膜間できれいに剥がれるので、型表面に傷・汚れが付着し難く、型寿命が向上する。  According to the present embodiment, an optical element having fine irregularities can be easily released without using a release material, so that the refractive index of the optical element is not affected. Since it peels cleanly between metal films, it is difficult for scratches and dirt to adhere to the mold surface and the mold life is improved.

図３は、上記の金属膜形成（２）、成形（３）、及び型開き（４）を一つの装置内で処理することが可能な成形装置の構成例を示す。この装置は、回転ドラム成形装置８であり、軸回りに回転駆動されるドラムを備え、ドラムには型５が固定され、ドラムの周囲に各処理を行うステーションが設けられている。金属膜形成（２）のステーションでは、電気メッキ槽１０内のメッキ液１１に型５を浸漬し、金属膜６を形成する。金属膜６のメッキは、電源１３より電気メッキ槽１０内の電極１２から型５に電流を流すことで成される。次に、金属膜６をスプレー水洗／熱風乾燥するステーションがあり、次に、型５と型１５とにより形成したキャビティに真空／樹脂充填を行う成形（３）のステーションがあり、さらに、冷却／離型により、型開き（４）を行うステーションがある。こうして得られた微細構造体７は、金属膜除去（５）へ移される。  FIG. 3 shows a configuration example of a molding apparatus capable of processing the metal film formation (2), molding (3), and mold opening (4) in one apparatus. This apparatus is a rotary drum forming apparatus 8 and includes a drum that is driven to rotate about an axis. Amold 5 is fixed to the drum, and a station for performing each processing is provided around the drum. In the metal film formation (2) station, themold 5 is immersed in theplating solution 11 in theelectroplating tank 10 to form themetal film 6. Themetal film 6 is plated by supplying a current from thepower source 13 to themold 5 from theelectrode 12 in theelectroplating tank 10. Next, there is a station for washing themetal film 6 with spray water / hot air drying, then there is a molding (3) station for filling the cavity formed by themold 5 and themold 15 with vacuum / resin, and further cooling / There is a station that performs mold opening (4) by mold release. Themicrostructure 7 thus obtained is transferred to the metal film removal (5).

（実施例２）
本実施例２は、上述図２に示した実施例１において金属膜形成の前処理として、型表面を酸化処理する工程を付加したものである。型として、材質が銅の金属へ切削加工方法により光学素子となる形状を形成後、酸化処理を行なう。ここに、酸化処理は、５％重クロム酸カリウム水溶液へ浸漬することにより行い、液温：２３℃、処理時間：３０秒とした。酸化処理後は、ニッケルメッキにより０．２μｍの金属膜を形成した。ここに、ニッケルメッキ液組成は、スルファミン酸ニッケル：３００ｇ／Ｌ、ホウ酸：４０ｇ／Ｌ、塩酸：５ｍＬ／Ｌとした。(Example 2)
In the second embodiment, a step of oxidizing the mold surface is added as a pretreatment for forming the metal film in the first embodiment shown in FIG. As a mold, a shape that becomes an optical element is formed on a copper metal material by a cutting method, and then an oxidation treatment is performed. Here, the oxidation treatment was performed by immersing in a 5% potassium dichromate aqueous solution, and the liquid temperature was 23 ° C. and the treatment time was 30 seconds. After the oxidation treatment, a 0.2 μm metal film was formed by nickel plating. Here, the nickel plating solution composition was nickel sulfamate: 300 g / L, boric acid: 40 g / L, and hydrochloric acid: 5 mL / L.

上記ニッケルメッキは、析出応力が１５ｋｇ／ｍｍ^３と大きい被膜であったが、被膜の割れや剥がれが観られなかった。また、ニッケル金属膜上にセロハンテープを貼り付け剥離するテープテストでは、ニッケル金属膜と型の界面で容易に剥離できた。次に、実施例１と同様、成形後に型開きを行うと、上記ニッケル金属膜は型との界面で容易に剥離でき、ニッケル金属膜は光学素子となる樹脂側に密着していた。その後、ニッケル金属膜は、塩化銅と過酸化水素を混合したエッチング液にてエッチング除去した。The nickel plating was a film having a large precipitation stress of 15 kg / mm³ , but no cracking or peeling of the film was observed. Further, in the tape test in which the cellophane tape was applied to the nickel metal film and peeled off, it was easily peeled off at the interface between the nickel metal film and the mold. Next, as in Example 1, when the mold was opened after molding, the nickel metal film was easily peeled off at the interface with the mold, and the nickel metal film was in close contact with the resin side serving as an optical element. Thereafter, the nickel metal film was removed by etching with an etching solution in which copper chloride and hydrogen peroxide were mixed.

酸化処理する薬品としては、上記重クロム酸カリウムの他、過酸化水素水、過マンガン酸カリウムなどが挙げられ、これらの濃度、温度が高く処理時間が長いほど酸化被膜は厚くなり、容易な離型ができる。しかし、その一方、ニッケルやクロム金属膜は内部応力が大きいため、成膜途中や成形前の外形加工などにより、金属膜の割れや剥離が生じる。上記酸化処理を最適化することで、成形工程まで金属膜の割れや剥離が生じることなく、かつ容易な離型が可能となる。  Examples of chemicals to be oxidized include potassium dichromate, hydrogen peroxide, potassium permanganate and the like. The higher the concentration and temperature and the longer the treatment time, the thicker the oxide film becomes and the easier it is to release it. I can mold. However, since nickel and chromium metal films have a large internal stress, the metal film is cracked or peeled off during film formation or external processing before forming. By optimizing the oxidation treatment, the metal film can be easily released without cracking or peeling off until the forming step.

上記酸化処理を付加することにより、処理薬品の濃度、温度、時間を変えることで、金属膜の型に対する密着強度を容易に制御できるため、離型工程まで型に金属膜を密着保持させ、かつ離型を容易にできる。  By adding the oxidation treatment, by changing the concentration, temperature, and time of the treatment chemical, the adhesion strength of the metal film to the mold can be easily controlled, so that the metal film is held in close contact with the mold until the mold release step, and Release is easy.

（実施例３）
上記実施例２におけるニッケルメッキ液へ硫黄を１ｐｐｍ以上添加し、複合メッキにより金属膜へ含有させた。成形樹脂には、ポリカーボネイトを用いて成形し、その後、この金属膜を２０％過硫酸ナトリウム水溶液に５分浸漬させて溶解除去した。上記金属膜及び溶剤を用いることにより、金属層の除去が容易となり、また、この方法で製造された光学素子は、外観及び屈折率、透過率の光学特性に劣化が見られなかった。(Example 3)
1 ppm or more of sulfur was added to the nickel plating solution in Example 2 described above and contained in the metal film by composite plating. The molding resin was molded using polycarbonate, and then this metal film was immersed in a 20% aqueous solution of sodium persulfate for 5 minutes for dissolution and removal. By using the metal film and the solvent, it is easy to remove the metal layer, and the optical element manufactured by this method has no deterioration in appearance, refractive index, and optical characteristics of transmittance.

ここで、比較例として、ニッケルメッキ液に硫黄を含有しないメッキ液を用いて金属膜を形成し、同様に成形後に２０％過硫酸ナトリウム水溶液に１０分浸漬したが、ニッケル金属膜は溶解しなかった。そこで、５０％硝酸水溶液に１分浸漬し、ニッケル金属膜を溶解除去した。この結果、ポリカーボネイトは硝酸により薄黄色に変色し、光透過率が低下した。  Here, as a comparative example, a metal film was formed by using a plating solution that does not contain sulfur as a nickel plating solution, and similarly immersed in a 20% aqueous solution of sodium persulfate for 10 minutes after molding, but the nickel metal film did not dissolve. It was. Therefore, the nickel metal film was dissolved and removed by immersing in a 50% nitric acid aqueous solution for 1 minute. As a result, the polycarbonate was turned pale yellow by nitric acid and the light transmittance was lowered.

（実施例４）
本実施例４は、上述実施例１の金属膜形成工程において、金属膜として型材よりも線膨張率の小さい金属を用い、光学素子成形工程と光学素子離型工程の間に、型の温度を成形温度から低下させる型冷却工程を備えたものである。型材と金属膜との間の熱膨張の差により、剥離し易くなり、離型工程時に光学素子の欠けが防止できる。Example 4
In Example 4, the metal film forming process of Example 1 described above uses a metal having a smaller linear expansion coefficient than the mold material as the metal film, and the mold temperature is changed between the optical element molding process and the optical element release process. A mold cooling step for lowering the molding temperature is provided. Due to the difference in thermal expansion between the mold material and the metal film, it becomes easy to peel off, and chipping of the optical element can be prevented during the mold release process.

型材料として、熱膨張率１７．３×１０^−６のＳＵＳ３０４、金属膜として熱膨張率１０．２×１０^−６ニッケルクロム合金を用いた。成形を２６０℃にて行い、５０℃まで冷却後に離型を行なった。上記合金金属膜は、型との界面で容易に剥離でき、合金金属膜は光学素子となる樹脂側に密着していた。型材及び金属膜に用いる材料としては、熱膨張率が、型材＞金属膜材料となればよく、下表の各材料の熱膨張率より、材料組合せを適宜選ぶことができる。

As the mold material, SUS304 having a thermal expansion coefficient of 17.3 × 10⁻⁶ was used, and as the metal film, a thermal expansion coefficient of 10.2 × 10⁻⁶ nickel chromium alloy was used. Molding was performed at 260 ° C., and the mold was released after cooling to 50 ° C. The alloy metal film was easily peeled off at the interface with the mold, and the alloy metal film was in close contact with the resin side serving as an optical element. As a material used for the mold material and the metal film, it is sufficient that the coefficient of thermal expansion is mold material> metal film material, and the material combination can be appropriately selected based on the coefficient of thermal expansion of each material in the table below.

本発明方法により製造される光学素子の表面形状の例を図４（ａ）（ｂ）（ｃ）に示す。光学素子としては、微細かつ高精度表面形状を必要とする光導波路２ａ、光学レンズ２ｂ、フィルター、回折格子２ｃ、プリズム及び光学記録媒体などが挙げられる。成形材料としては、光透過するメタクリル樹脂、ポリカーボネイト樹脂、ポリスチレン樹脂、ポリエステル樹脂、ポリオレフィン樹脂、透明ポリイミド、含フッ素透明ポリマ等が挙げられる。本発明方法によれば、離型時の傷・欠けが少ない凹凸形状を形成できるので、性能劣化を防止できる。なお、本発明は、上記実施例構成に限られるものではなく、発明の趣旨を変更しない範囲で種々の変形が可能である。  Examples of the surface shape of the optical element manufactured by the method of the present invention are shown in FIGS. 4 (a), 4 (b) and 4 (c). Examples of the optical element include anoptical waveguide 2a, an optical lens 2b, a filter, adiffraction grating 2c, a prism, and an optical recording medium that require a fine and high-precision surface shape. Examples of the molding material include light-transmitting methacrylic resin, polycarbonate resin, polystyrene resin, polyester resin, polyolefin resin, transparent polyimide, and fluorine-containing transparent polymer. According to the method of the present invention, it is possible to form a concavo-convex shape with few scratches / chips at the time of mold release, thereby preventing performance deterioration. The present invention is not limited to the configuration of the above embodiment, and various modifications can be made without departing from the spirit of the invention.

本発明方法により製造される光学素子の一例を示す斜視図。The perspective view which shows an example of the optical element manufactured by the method of this invention.本発明の一実施例に係る光学素子の製造方法を概念的に示す工程図。Process drawing which shows notionally the manufacturing method of the optical element which concerns on one Example of this invention.金属膜形成、成形、及び型開きを一つの装置内で処理することが可能な成形装置の例を示す側面構成図。The side surface block diagram which shows the example of the shaping | molding apparatus which can process metal film formation, shaping | molding, and mold opening in one apparatus.本発明方法により製造される光学素子の表面形状の例を示す側断面図。The sectional side view which shows the example of the surface shape of the optical element manufactured by the method of this invention.

符号の説明Explanation of symbols

１ 光学素子
２ 成形樹脂
５ 型
５ａ 凹凸部（微細凹凸）
６ 金属膜
７’ 微細構造体（光学素子）DESCRIPTION OFSYMBOLS 1Optical element 2Molding resin 5 Type |mold 5a Uneven part (fine unevenness)
6 Metal film 7 'Fine structure (optical element)

Claims (4)

Translated fromJapanese

微細凹凸を持つ型表面に、型材質に対して成形温度下で拡散しない金属膜を形成する金属膜形成工程と、
前記微細凹凸を持つ型を少なくとも一面に持つキャビティ内に樹脂を充填・硬化させて、微細構造体を形成する光学素子成形工程と、
前記型表面より前記金属膜を剥離させ、該金属膜が微細構造体表面に付着した状態で型開きを行う光学素子離型工程と、
前記樹脂を溶解せず金属膜層のみを溶解可能な溶剤に前記微細構造体を浸すことで、微細構造体表面より金属膜を除去する金属膜除去工程と、
を備えたことを特徴とする光学素子の製造方法。A metal film forming process for forming a metal film that does not diffuse at a molding temperature on the mold surface with fine irregularities;
An optical element molding step of forming a microstructure by filling and curing a resin in a cavity having at least one surface having a mold with fine irregularities;
An optical element releasing step of peeling the metal film from the mold surface and performing mold opening in a state where the metal film is attached to the microstructure surface;
A metal film removing step of removing the metal film from the surface of the microstructure by immersing the microstructure in a solvent capable of dissolving only the metal film layer without dissolving the resin;
An optical element manufacturing method comprising: 前記金属膜形成工程において、金属膜として銅、ニッケル、クロム、コバルト又はそれらの化合物を形成し、
前記金属膜除去工程において、溶剤として過酸化水素、過マンガン酸塩、重クロム酸塩を用いることを特徴とする請求項１記載の光学素子の製造方法。In the metal film forming step, copper, nickel, chromium, cobalt or a compound thereof is formed as the metal film,
2. The method of manufacturing an optical element according to claim 1, wherein hydrogen peroxide, permanganate, or dichromate is used as a solvent in the metal film removing step. 前記金属膜形成工程において、金属膜として型材よりも線膨張率の小さい金属を用い、
前記光学素子成形工程と光学素子離型工程の間に、型の温度を成形温度から低下させる型冷却工程を備えたことを特徴とする請求項１記載の光学素子の製造方法。In the metal film forming step, a metal having a smaller linear expansion coefficient than the mold material is used as the metal film,
2. The method of manufacturing an optical element according to claim 1, further comprising a mold cooling step for lowering the mold temperature from the molding temperature between the optical element molding step and the optical element release step. 請求項１乃至請求項３のいずれかに記載の製造方法を用いて製造されたことを特徴とする光学素子。  An optical element manufactured using the manufacturing method according to claim 1.

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