JP2004035982A

JP2004035982A - Electroplating method for optical fiber

Info

Publication number: JP2004035982A
Application number: JP2002197907A
Authority: JP
Inventors: Toru Tateishi; 立石　徹; Yasuhide Matsumoto; 松本　泰英
Original assignee: Furukawa Electric Co Ltd
Current assignee: Furukawa Electric Co Ltd
Priority date: 2002-07-05
Filing date: 2002-07-05
Publication date: 2004-02-05

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that the film thicknesses of plating films for respective optical fibers are made nonuniform. <P>SOLUTION: In the electroplating method for optical fibers, the value of electric current applied to a substrate for plating film-deposited on the portion to be plated in each optical fiber on the application of voltage is individually controlled. The cathode sides of a plurality of power sources prepared for respective optical fibers are individually connected to the substrate for plating film-deposited on the portion of each optical fiber. The cathode sides of the power sources are connected to electrodes in a plating liquid, and voltage is applied to the space between the substrate for plating and the electrode. Into a current passage formed for each optical fiber, a resistance sufficiently higher than the average resistance value of these current passages is inserted. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、１つのメッキ槽を用いて複数本の光ファイバに同時に電解メッキを施す方法に関するものである。
【０００２】
【従来の技術】
従来、１つのメッキ槽で複数本の光ファイバに同時に電解メッキを施す際には図４に示すようにしていた。即ち、メッキ槽Ａ内のメッキ液Ｂに浸した陽電極（Ｐｔ板）Ｃを定電流電源Ｄの陽極側に接続し、同メッキ液Ｂに浸した複数本の光ファイバＥの被メッキ部分Ｆを同定電流電源Ｄの陰極側に並列接続して、メッキ液所定の電流密度となる定電流を一定時間通電していた。尚、光ファイバＥの被メッキ部分Ｆには、蒸着、スパッタ、無電解メッキ等により予めメッキ用下地が成膜されている。
【０００３】
【発明が解決しようとする課題】
前記のようにして光ファイバに電解メッキを施すことには次のような課題があった。光ファイバの被メッキ部分の面積は非常に小さい。例えば、φ１２５μｍの光ファイバの端末部２０ｍｍを被メッキ部分とした場合、その面積は７．８５ｍｍ^２となる。さらに、面積が７．８５ｍｍ^２の被メッキ部分に通電される電流の密度を０．５０Ａ／ｄｍ^２とするためには、設定電流値を０．７５ｍＡ×ファイバ本数という微小な値に設定する必要がある。このとき、被メッキ部分に成膜されているメッキ用下地の抵抗や電極と光ファイバとの接触抵抗等にばらつきがあると、もともとの被メッキ部分の面積が小さく抵抗値が低いために、複数本の光ファイバの被メッキ部分に流れる電流の大きさが各光ファイバ間で大きくばらつく。この結果、大きな電流が流れた光ファイバの被メッキ部分にメッキが集中し、各光ファイバ間でメッキの膜厚が不均一になってしまう。かかる不具合は、被メッキ部分の抵抗のばらつきが電流経路の抵抗に対して十分に小さな場合には大した問題とはならないが、光ファイバの被メッキ部分のように、その抵抗のばらつきがが電流経路の抵抗と比較して大きな場合には大きな問題となる。
【０００４】
そこで本件発明者らは、図４に示す各光ファイバＥの被メッキ部分Ｆにおける電流密度を０．５０　Ａ／ｄｍ^２とするために、同図に示す定電流電源Ｄの電流値を３．７５ｍＡ（０．７５ｍＡ×５本）に設定して１４０秒間通電する実験を行った。この結果、被メッキ部分Ｆに大量のメッキが付いた光ファイバＥがある一方で、メッキがまったく付いていない光ファイバＥもあり、膜厚は０．０〜２．０μｍの範囲でばらついていた。
【０００５】
【課題を解決するための手段】
本発明の目的は、複数本の光ファイバに均一な膜厚のメッキを同時に施すことが可能な光ファイバの電解メッキ方法を提供することにある。
【０００６】
本発明の一つは、メッキ用下地としての導電性膜が成膜された複数本の光ファイバの被メッキ部分を１つのメッキ槽内のメッキ液に浸し、それら被メッキ部分のメッキ用下地とメッキ液内の電極との間に電圧を印加して被メッキ部分にメッキを施す光ファイバへの電解メッキ方法であって、前記電圧印加時に各被メッキ部分のメッキ用下地に通電する電流の値を個別に制御するものである。
【０００７】
本発明の他の一つは、メッキ用下地としての導電性膜が成膜された複数本の光ファイバの被メッキ部分を１つのメッキ槽内のメッキ液に浸し、それら被メッキ部分のメッキ用下地とメッキ液内の電極との間に電圧を印加して被メッキ部分にメッキを施す光ファイバへの電解メッキ方法であって、各光ファイバ毎に用意された複数の電源の陰極側を各被メッキ部分のメッキ用下地に個別に接続し、それら電源の陽極側をメッキ液内の電極に接続して、メッキ用下地と電極との間に電圧を印加するものである。
【０００８】
本発明の他の一つは、メッキ用下地としての導電性膜が成膜された複数本の光ファイバの被メッキ部分を１つのメッキ槽内のメッキ液に浸し、それら被メッキ部分のメッキ用下地とメッキ液内の電極との間に電圧を印加して被メッキ部分にメッキを施す光ファイバへの電解メッキ方法であって、各被メッキ部分のメッキ用下地を電源の陰極側に並列接続し、電源の陽極側をメッキ液内の電極に接続すると共に、各光ファイバ毎に形成される電流経路に、これら電流経路の抵抗値よりも十分大きな抵抗値を有する抵抗を挿入した上で、メッキ用下地と電極との間に電圧を印加するものである。
【０００９】
本発明の他の一つは、各光ファイバ毎に形成される電流経路に挿入される抵抗の抵抗値を、それら電流経路の平均抵抗値の１０倍以上としたものである。
【００１０】
本発明の他の一つは、メッキ材料をＡｕとし、電圧印加時における被メッキ部分の電流密度を０．０１Ａ／ｄｍ^２〜１．００Ａ／ｄｍ^２としたものである。
【００１１】
【発明の実施の形態】
（実施形態１）
以下、本発明の実施例の一つを説明する。ここに示す実施例は、１つの電解槽を用いて５本の光ファイバの端部に同時に電解メッキを施すものである。具体的には図１に示すように、５本の光ファイバ１（１ａ〜１ｅ）の被メッキ部分２（２ａ〜２ｅ）に成膜されたメッキ用下地（導電性膜）を各光ファイバ１ａ〜１ｅ毎に用意された５つの定電流電源３（３ａ〜３ｅ）の陰極側に接続してメッキ槽４内のメッキ液５に浸し、陽電極（Ｐｔ板）６を前記定電流電源３ａ〜３ｅの陽極側に接続して同メッキ液５に浸す。即ち、各光ファイバ１ａ〜１ｅ毎に、定電流電源３の陽極側−陽電極４−メッキ液５−被メッキ部分（メッキ用下地）２−定電流電源３の陰極側という電流経路を形成する。もっとも、図１に示す配置が完了すれば（前記電流経路が形成されれば）、完了に至る手順には特に限定はない。例えば、被メッキ部分２ａ〜２ｅと陽電極６のどちらを先に定電流電源３ａ〜３ｂに接続してもよく、被メッキ部分２ａ〜２ｅと陽電極６のどちらを先にメッキ液５に浸してもよい。
【００１２】
尚、夫々の光ファイバ１ａ〜１ｅの被メッキ部分２ａ〜２ｅの長さは２０ｍｍであり、ここに成膜されているメッキ用下地の構成は、Ｔｉ／Ｎｉ／Ａｕである。また、夫々の膜厚はＴｉ膜：０．０２μｍ、Ｎｉ膜：０．０２μｍ、Ａｕ膜：０．０５μｍである。メッキ槽４は直径１５０ｍｍ、深さ１００ｍｍのビーカーである。メッキ液５は、亜硫酸金ナトリウム（Ｎａ_３Ａｕ（ＳＯ_３）_２）２．２％、無機酸塩５．０％、水（Ｈ_２Ｏ）８０％以上を含むＡｕメッキ用ノンシアン系メッキ液であり、指定電流密度は０．７Ａ／ｄｍ^２である。
【００１３】
図１に示す配置が完了したら、光ファイバ１本当たりの電流密度を０．５０Ａ／ｄｍ^２とするために、各定電流電源３ａ〜３ｅの電流設定値を０．３９５ｍＡに設定して通電を行い、各被メッキ部分２ａ〜２ｅのメッキ用下地と陽電極６との間に電圧を印加する。尚、このときのメッキレートは、理論上０．３２０μｍ／分となることが分かっている。そこで、目標膜厚を０．７５μｍとし、上記条件で１４０秒間通電する。メッキ前とメッキ後の各被メッキ部分２ａ〜２ｅの外径差から算出したメッキの膜厚は表１に示すとおりである。
【００１４】
【表１】

【００１５】
前記表１に示すように、５本の光ファイバ１ａ〜１ｅの全ておいて、ほぼ理論値どおり膜厚を得ることができた。また、各光ファイバ１ａ〜１ｅ間の膜厚のばらつきは、標準偏差で０．０１３μｍと極めて良好であった。
【００１６】
（実施形態２）
図４の各光ファイバＥ毎の電流経路の抵抗値を調べたところ、１１００〜１４００［Ω］の範囲でばらついており、その標準偏差は５０［Ω］程度であった、また、これら抵抗値の平均値は１２４０［Ω］であり、平均値に対してのばらつき（標準偏差）は５％程度であることがわかった。このばらつきの多くは、メッキ用の下地である導電性膜厚のばらつきによるものと、被メッキ部分Ｆとそこに接続された電源ケーブル（陰極側ケーブル）との接続部分Ｇの接触抵抗のばらつきによるものである。
【００１７】
そこで、本発明者らは、図２に示すように、メッキ槽４内のメッキ液５に浸した陽電極６を定電流電源３の陽極側に接続すると共に、同メッキ液５内の５本の光ファイバ１（１ａ〜１ｅ）の被メッキ部分２（２ａ〜２ｅ）に成膜されているメッキ用下地を電源ケーブル７を介して前記定電流電源３の陰極側に並列接続し、さらに、各光ファイバ１ａ〜１ｅ毎に形成された定電流電源３の陽極側−陽電極６−メッキ液５−被メッキ部分（メッキ用下地）２−電源ケーブル７−定電流電源３の陰極側という電流経路の夫々に、それら電流経路の平均抵抗値よりも十分大きな抵抗値（２０［ｋΩ］）を有する抵抗４ａ〜４ｅを挿入した。これにより、各電流経路の抵抗値の平均値に対するばらつきは０．２％になると予想される。
【００１８】
光ファイバ１本当たりの電流密度を０．５０Ａ／ｄｍ^２とするために、各電流経路の電流が０．３９５ｍＡになるように、０．３９５×５＝１．９７５ｍＡの電流を流すべく、図２の定電流電源３を用いて電圧を印加した。尚、このときのメッキレートは、実施形態１同様に理論上０．３２０μｍ／分となることが分かっている。そこで、目標膜厚を０．７５μｍとし、上記条件で１４０秒間通電する。メッキ前とメッキ後の各被メッキ部分２ａ〜２ｅの外径差から算出したメッキの膜厚を表２に示す。
【００１９】
【表２】

【００２０】
前記表２に示すように、５本の光ファイバ１ａ〜１ｅの全ておいて、ほぼ理論値どおり膜厚を得ることができた。また、各光ファイバ１ａ〜１ｅ間の膜厚のばらつきは、標準偏差で０．０２０μｍと極めて良好であった。
【００２１】
本実施形態では、各電流経路に２０［ｋΩ］の抵抗を挿入したが、挿入抵抗の値は任意に決定するとができる。もっとも、ほぼ理論値どおり膜厚を得ることが可能な程度にまで、各電流経路の抵抗値のばらつきを抑制するとの観点からは、これら電流経路の平均抵抗値の１０倍以上の抵抗値を有する抵抗を各電流経路に挿入することが望ましい。尚、本明細書における電流経路の抵抗値とは、光ファイバの被メッキ部分に成膜されたメッキ用下地の抵抗値と、そのメッキ用下地と電源ケーブルとの接触抵抗値と、電源ケーブル自体の抵抗値との合計抵抗値を意味する。
【００２２】
（実験例）
本件発明者らは、実施形態１及び実施形態２の光ファイバ１ａ〜１ｅと同様の光ファイバを使用し、１本当たりの電流密度を０．０５〜１．５０Ａ／ｄｍ^２まで変化させる実験を行った。尚、被メッキ部分の長さは２０ｍｍであり、目標膜厚は０．７５μｍである。本実験の具体的条件を表３に示す。また、実験結果から得られた電流密度とメッキ速度の関係を図３のグラフに示す。図３のグラフは、実際に得られたメッキの膜厚を設定したメッキ時間で除算して求めたメッキ速度をグラフ化したものである。
【００２３】
【表３】

【００２４】
本実験の結果、少なくとも次の３点が確認された。
（１）電流密度を０．１０Ａ／ｄｍ^２未満にすると、メッキ速度が０．１μｍ／分以下となり、非生産的であること。
（２）電流密度を１．００Ａ／ｄｍ^２よりも大きくすると、メッキ膜表面が赤黒く変色してしまうこと。
（３）電流密度が０．１０Ａ／ｄｍ^２以上１．００Ａ／ｄｍ^２以下の範囲内であれば、前記（１）（２）のような問題がなく、ほぼ理論値どおりの均一な膜厚が得られること。
【００２５】
さらに本件発明者らは、電流密度を０．１０Ａ／ｄｍ^２以上１．００Ａ／ｄｍ^２以下の一定値とし、被メッキ部分の長さを５ｍｍ〜５０ｍｍまで変化させる実験も行った。この結果、被メッキ部分の長さに関わらず、ほぼ理論値どおりの均一な膜厚が得られた。
【００２６】
【発明の効果】
本発明の光ファイバへの電解メッキ方法によれば、メッキ液に浸された複数本の光ファイバの被メッキ部分に成膜されているメッキ用下地に流れる電流の大きさにばらつきが発生しない。従って、複数本の光ファイバの被メッキ部分にほぼ理論値どおりの膜厚のメッキを施すことができる。特に、被メッキ部分の電流密度を０．０１Ａ／ｄｍ^２〜１．００Ａ／ｄｍ^２とすれば、生産的なメッキ速度を確保しつつ、複数本の光ファイバの被メッキ部分にほぼ理論値どおりの膜厚のメッキを施すことができ、メッキ表面の変色その他の不具合も発生しない。
【図面の簡単な説明】
【図１】本発明の光ファイバへの電解メッキ方法の一例を示す説明図。
【図２】本発明の光ファイバへの電解メッキ方法の他例を示す説明図。
【図３】電流密度とメッキ速度の関係を示す図。
【図４】従来の光ファイバへの電解メッキ方法の一例を示す説明図。
【符号の説明】
１ａ〜１ｅ　　光ファイバ
２ａ〜２ｅ　　被メッキ部分
３ａ〜３ｅ　　定電流電源
４　メッキ槽
５　メッキ液
６　陽電極
７　電源ケーブル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for simultaneously performing electrolytic plating on a plurality of optical fibers using one plating tank.
[0002]
[Prior art]
Conventionally, when a plurality of optical fibers are simultaneously subjected to electrolytic plating in one plating tank, as shown in FIG. That is, the positive electrode (Pt plate) C immersed in the plating solution B in the plating tank A is connected to the anode side of the constant current power supply D, and the plated portions F of the plurality of optical fibers E immersed in the plating solution B are connected. Was connected in parallel to the cathode side of the identification current power supply D, and a constant current having a predetermined current density of the plating solution was supplied for a predetermined time. A plating base is previously formed on the portion F to be plated of the optical fiber E by vapor deposition, sputtering, electroless plating, or the like.
[0003]
[Problems to be solved by the invention]
Applying electrolytic plating to an optical fiber as described above has the following problems. The area of the portion to be plated of the optical fiber is very small. For example, if the terminal portion of the optical fiber having a diameter of 125 μm is 20 mm as a portion to be plated, its area is 7.85 mm ² . Further, in order to set the density of the current supplied to the portion to be plated having an area of 7.85 mm ² to 0.50 A / dm ² , it is necessary to set the set current value to a minute value of 0.75 mA × the number of fibers. There is. At this time, if there is variation in the resistance of the plating base formed on the plated portion or the contact resistance between the electrode and the optical fiber, the area of the originally plated portion is small and the resistance value is low. The magnitude of the current flowing through the portion of the optical fiber to be plated greatly varies among the optical fibers. As a result, plating concentrates on a portion to be plated of the optical fiber through which a large current has flowed, and the thickness of the plated film becomes uneven between the optical fibers. Such a problem does not cause a serious problem when the variation in the resistance of the plated portion is sufficiently smaller than the resistance of the current path. However, as in the plated portion of the optical fiber, the variation in the resistance is large. When the resistance is large compared to the resistance of the path, it becomes a big problem.
[0004]
Therefore, the present inventors set the current value of the constant current power supply D shown in FIG. 4 to 3.0 A / dm ² in order to set the current density in the plated portion F of each optical fiber E shown in FIG. An experiment was conducted in which the current was set at 75 mA (0.75 mA × 5) and energized for 140 seconds. As a result, while there was an optical fiber E with a large amount of plating on the portion F to be plated, there was also an optical fiber E with no plating, and the film thickness varied in the range of 0.0 to 2.0 μm. .
[0005]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for electroplating an optical fiber that can simultaneously apply a plurality of optical fibers to a uniform thickness.
[0006]
One aspect of the present invention is to immerse portions to be plated of a plurality of optical fibers on which a conductive film as a substrate for plating has been formed in a plating solution in one plating tank, and to form a plating underlayer on the portions to be plated. An electrolytic plating method for an optical fiber for plating a portion to be plated by applying a voltage between electrodes in a plating solution, wherein a value of a current flowing through a plating base of each portion to be plated when the voltage is applied. Are individually controlled.
[0007]
Another aspect of the present invention is to immerse portions to be plated of a plurality of optical fibers on which a conductive film as a base for plating has been formed in a plating solution in one plating tank, and to plate these portions for plating. This is an electrolytic plating method for an optical fiber for plating a portion to be plated by applying a voltage between a base and an electrode in a plating solution, wherein a plurality of power supplies prepared for each optical fiber have a cathode side. These are individually connected to the plating base of the portion to be plated, the anode side of the power supply is connected to the electrode in the plating solution, and a voltage is applied between the plating base and the electrode.
[0008]
Another aspect of the present invention is to immerse portions to be plated of a plurality of optical fibers on which a conductive film as a base for plating has been formed in a plating solution in one plating tank, and to plate these portions for plating. This is an electrolytic plating method for an optical fiber that applies a voltage between the base and the electrode in the plating solution to plate the part to be plated. The plating base for each part to be plated is connected in parallel to the cathode side of the power supply. Then, while connecting the anode side of the power supply to the electrode in the plating solution, inserting a resistor having a resistance value sufficiently larger than the resistance value of these current paths into the current paths formed for each optical fiber, A voltage is applied between the plating base and the electrode.
[0009]
Another aspect of the present invention is that the resistance value of a resistor inserted into a current path formed for each optical fiber is 10 times or more the average resistance value of the current path.
[0010]
Another one of the present invention, the plating material as Au, is obtained by the current density of the to-be-plated portion at the time of voltage application and ^{^{0.01A / dm 2 ~1.00A / dm 2}} .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, one embodiment of the present invention will be described. In the embodiment shown here, the ends of five optical fibers are simultaneously subjected to electrolytic plating using one electrolytic bath. Specifically, as shown in FIG. 1, a plating base (conductive film) formed on a portion to be plated 2 (2a to 2e) of five optical fibers 1 (1a to 1e) is applied to each optical fiber 1a. 5e are connected to the cathode sides of five constant current power supplies 3 (3a to 3e) prepared for each of the electrodes and immersed in the plating solution 5 in the plating tank 4, and the positive electrode (Pt plate) 6 is connected to the constant current power supplies 3a to The electrode 3e is connected to the anode side and immersed in the plating solution 5. That is, for each of the optical fibers 1a to 1e, a current path is formed between the anode side of the constant current power supply 3, the positive electrode 4, the plating solution 5, the portion to be plated (base for plating), and the cathode side of the constant current power supply 3. . However, if the arrangement shown in FIG. 1 is completed (if the current path is formed), there is no particular limitation on the procedure leading to completion. For example, which of the plated parts 2a to 2e and the positive electrode 6 may be connected to the constant current power supplies 3a to 3b first, and which of the plated parts 2a to 2e and the positive electrode 6 is immersed in the plating solution 5 first. You may.
[0012]
The lengths of the portions 2a to 2e to be plated of the optical fibers 1a to 1e are 20 mm, and the configuration of the plating underlayer formed here is Ti / Ni / Au. The thickness of each film is 0.02 μm for the Ti film, 0.02 μm for the Ni film, and 0.05 μm for the Au film. The plating tank 4 is a beaker having a diameter of 150 mm and a depth of 100 mm. The plating solution 5 is a non-cyanide plating solution for Au plating containing 2.2% of sodium gold sulfite (Na ₃ Au (SO ₃ ) ₂ ), 5.0% of an inorganic acid salt, and 80% or more of water (H ₂ O). Yes, and the specified current density is 0.7 A / dm ² .
[0013]
When the arrangement shown in FIG. 1 is completed, in order to set the current density per optical fiber to 0.50 A / dm ² , the current setting value of each of the constant current power supplies 3 a to 3 e is set to 0.395 mA, and energization is performed. Then, a voltage is applied between the plating base of each of the portions to be plated 2 a to 2 e and the positive electrode 6. It has been found that the plating rate at this time is theoretically 0.320 μm / min. Therefore, the target film thickness is set to 0.75 μm, and the current is supplied for 140 seconds under the above conditions. The plating film thickness calculated from the outer diameter difference between the plated portions 2a to 2e before plating and after plating is as shown in Table 1.
[0014]
[Table 1]

[0015]
As shown in Table 1 above, in all of the five optical fibers 1a to 1e, the film thickness could be obtained almost according to the theoretical value. Further, the variation of the film thickness among the optical fibers 1a to 1e was extremely good with a standard deviation of 0.013 μm.
[0016]
(Embodiment 2)
When the resistance value of the current path for each optical fiber E in FIG. 4 was examined, it varied in the range of 1100 to 1400 [Ω], and the standard deviation was about 50 [Ω]. Was 1240 [Ω], and it was found that the variation (standard deviation) from the average value was about 5%. Most of the variation is caused by the variation in the conductive film thickness serving as the base for plating and the variation in the contact resistance of the connection portion G between the portion F to be plated and the power cable (cathode side cable) connected thereto. Things.
[0017]
Therefore, as shown in FIG. 2, the present inventors connect the positive electrode 6 immersed in the plating solution 5 in the plating bath 4 to the anode side of the constant current power supply 3 and The plating bases formed on the portions 2 (2a to 2e) to be plated of the optical fibers 1 (1a to 1e) are connected in parallel to the cathode side of the constant current power supply 3 via a power cable 7; The current between the anode side of the constant current power supply 3 formed for each of the optical fibers 1a to 1e, the positive electrode 6, the plating solution 5, the portion to be plated (base for plating), the power supply cable 7, and the cathode side of the constant current power supply 3. In each of the paths, resistors 4a to 4e having a resistance value (20 [kΩ]) sufficiently larger than the average resistance value of the current paths were inserted. As a result, the variation of the resistance value of each current path with respect to the average value is expected to be 0.2%.
[0018]
In order to set the current density per optical fiber to 0.50 A / dm ² , a current of 0.395 × 5 = 1.975 mA is applied so that the current of each current path becomes 0.395 mA. The voltage was applied using the constant current power supply 3 of No. 2. It is known that the plating rate at this time is theoretically 0.320 μm / min as in the first embodiment. Therefore, the target film thickness is set to 0.75 μm, and the current is supplied for 140 seconds under the above conditions. Table 2 shows the plating film thickness calculated from the outer diameter difference between the plated portions 2a to 2e before and after plating.
[0019]
[Table 2]

[0020]
As shown in Table 2, in all of the five optical fibers 1a to 1e, the film thickness could be obtained almost according to the theoretical value. Further, the variation of the film thickness among the optical fibers 1a to 1e was extremely good with a standard deviation of 0.020 μm.
[0021]
In the present embodiment, a resistance of 20 [kΩ] is inserted in each current path, but the value of the inserted resistance can be arbitrarily determined. However, from the viewpoint of suppressing the variation in the resistance value of each current path to such an extent that the film thickness can be obtained as almost the theoretical value, the current paths have a resistance value which is 10 times or more the average resistance value. It is desirable to insert a resistor in each current path. In this specification, the resistance value of the current path is defined as the resistance value of the plating base formed on the plated portion of the optical fiber, the contact resistance value between the plating base and the power cable, and the power cable itself. And the total resistance value.
[0022]
(Experimental example)
The present inventors conducted an experiment in which the same optical fibers as the optical fibers 1a to 1e of the first and second embodiments were used and the current density per fiber was changed from 0.05 to 1.50 A / dm ^2. went. The length of the portion to be plated is 20 mm, and the target film thickness is 0.75 μm. Table 3 shows the specific conditions of this experiment. FIG. 3 is a graph showing the relationship between the current density and the plating rate obtained from the experimental results. The graph of FIG. 3 is a graph of the plating speed obtained by dividing the actually obtained plating film thickness by the set plating time.
[0023]
[Table 3]

[0024]
As a result of this experiment, at least the following three points were confirmed.
(1) When the current density is less than 0.10 A / dm ² , the plating rate becomes 0.1 μm / min or less, which is unproductive.
(2) When the current density is larger than 1.00 A / dm ² , the surface of the plating film is discolored to red and black.
(3) Within the range a current density of 0.10 A / dm ² or more 1.00A / dm ² or less, wherein (1) (2) there is no problem, such as a uniform thickness of approximately theoretical Can be obtained.
[0025]
Further, the present inventors conducted an experiment in which the current density was set to a constant value of 0.10 A / dm ² or more and 1.00 A / dm ² or less, and the length of the portion to be plated was changed from 5 mm to 50 mm. As a result, a uniform film thickness almost as expected was obtained irrespective of the length of the portion to be plated.
[0026]
【The invention's effect】
According to the method for electroplating optical fibers of the present invention, there is no variation in the magnitude of the current flowing through the plating base formed on the portions to be plated of the plurality of optical fibers immersed in the plating solution. Therefore, the plated portions of the plurality of optical fibers can be plated with a film thickness substantially equal to the theoretical value. In particular, if the current density of the plating part and ^{^{0.01A / dm 2 ~1.00A / dm 2}} , while ensuring the productive plating rate, approximately theoretical to be plated portion of the plurality of optical fibers , And no discoloration or other problems occur on the plating surface.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a method for electrolytic plating an optical fiber according to the present invention.
FIG. 2 is an explanatory view showing another example of the electrolytic plating method for an optical fiber of the present invention.
FIG. 3 is a diagram showing a relationship between current density and plating speed.
FIG. 4 is an explanatory view showing an example of a conventional method for electrolytic plating an optical fiber.
[Explanation of symbols]
1a-1e Optical fiber 2a-2e Plated portion 3a-3e Constant current power supply 4 Plating tank 5 Plating solution 6 Positive electrode 7 Power supply cable

Claims

The portions to be plated of a plurality of optical fibers on which a conductive film as a base for plating is formed are immersed in a plating solution in one plating tank, and the plating base of the portions to be plated and the electrodes in the plating solution are immersed. A method for electrolytic plating an optical fiber for plating a portion to be plated by applying a voltage therebetween, wherein individually controlling the value of a current supplied to a plating base of each portion to be plated at the time of applying the voltage. Characteristic electrolytic plating method for optical fiber.

The portions to be plated of a plurality of optical fibers on which a conductive film as a base for plating is formed are immersed in a plating solution in one plating tank, and the plating base of the portions to be plated and the electrodes in the plating solution are immersed. A method for electrolytic plating an optical fiber in which a voltage is applied in between to apply plating to a portion to be plated, in which the cathode side of a plurality of power supplies prepared for each optical fiber is individually applied to a plating base of each portion to be plated. And an anode side of the power source is connected to an electrode in a plating solution, and a voltage is applied between the plating base and the electrode.

The portions to be plated of a plurality of optical fibers on which a conductive film as a base for plating is formed are immersed in a plating solution in one plating tank, and the plating base of the portions to be plated and the electrodes in the plating solution are immersed. This is an electrolytic plating method for an optical fiber in which a portion to be plated is plated by applying a voltage therebetween, wherein a plating base of each portion to be plated is connected in parallel to a cathode side of a power supply, and an anode side of the power supply is plated with a plating solution. In addition to connecting to the electrodes inside, and inserting a resistor having a resistance value sufficiently larger than the resistance value of these current paths into the current paths formed for each optical fiber, A method for electrolytic plating an optical fiber, comprising applying a voltage.

4. The method according to claim 3, wherein a resistance value of a resistor inserted into a current path formed for each optical fiber is at least 10 times an average resistance value of the current path. .

The plating material as Au, according to any one of claims 1 to 4, characterized in that a 0.01A ^/ dm ² ~1.00A ^/ dm 2 of current density of the to-be-plated portion at the time of voltage application Electroplating method for optical fiber.