Optical fiber surface metallization method

Abstract

The invention discloses an optical fiber surface metallization method, and relates to the technical field of optical fiber surface treatment.The method comprises the following specific steps that S1, a protective layer and oil are removed, specifically, an optical fiber is immersed in concentrated sulfuric acid to be soaked to remove the protective layer, and an alkaline solution is adopted to treat grease and other dirt on the surface of the optical fiber; then, deionized water is used for ultrasonic cleaning; s2, coarsening: carrying out weak corrosion on the surface of the optical fiber by using hydrofluoric acid; s3, sensitizing: processing the optical fiber by using a sensitizing solution to enable the surface of the optical fiber to adsorb some substances easy to oxidize; s4, activating: activating the surface of the sensitized optical fiber by means of an activating solution palladium chloride solution with catalytic activity; s5, chemical plating: depositing a layer of Ni-P alloy on the surface of the optical fiber by adopting a chemical nickel plating method; and S6, electroplating: adopting an electroplating method to thicken the chemically plated optical fiber to improve the mechanical reliability and high temperature resistance of the optical fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber surface treatment, and in particular to a method for optical fiber surface metallization. Background Art

[0002] Fiber optic sensing technology, rapidly developing alongside the advancement of optical communication technology, uses light as a signal carrier and optical fiber as a medium to sense and transmit external signals. Compared to traditional sensors, fiber optic sensors offer a range of unique advantages, including high sensitivity, high voltage resistance, corrosion resistance, immunity to electromagnetic interference, high insulation, wide transmission bandwidth, large dynamic range, flexible optical paths, ease of connection to central computers, compact size, light weight, and simple structure.

[0003] The key issue with buried optical fiber is protecting the embedded portion of the fiber from damage during the heat-pressing and curing process. A common method is to use adhesives such as epoxy resin. However, this method can cause relative movement between the adhesive, the object being measured, the fiber coating, and the fiber core and coating, resulting in the measured data not accurately reflecting the stress and strain of the object being measured. Therefore, metallizing the surface of the quartz optical fiber and then embedding it with a soldered seal can solve this problem.

[0004] Optical fibers are primarily composed of SiO₂ and have a very small diameter, typically around 120 µm, making them susceptible to damage or breakage. Because optical fibers are non-conductors, plating a metal layer to a certain thickness requires metallization before electroplating.

[0005] There are many methods for forming metal films. For optical fibers, there are several approaches: melt coating of low-melting-point metals, sputtering, vapor deposition, and chemical liquid deposition. Because the surface of a fiber Bragg grating sensor is very small, it is difficult to deposit a uniform metal film on it using electron sputtering or vacuum evaporation. Both methods require temperatures around 300°C, a temperature at which ordinary optical fibers tend to become brittle and fracture, and gratings are prone to degradation. Chemical liquid deposition utilizes chemical plating to evenly deposit metal on the fiber surface to protect it. The fiber is then encapsulated using welding. This method not only improves measurement accuracy but also expands the scope of engineering applications.

[0006] Some experts and scholars in China have also studied the metallization of optical fiber surfaces. Zhong Liang used chemical copper plating on the optical fiber surface, but did not continue with electroplating. Wang Jing also achieved uniform coatings by chemically plating nickel-phosphorus alloys and electroplating copper, gold, and zinc, but did not use electroplating nickel. Summary of the Invention

[0007] The purpose of the present invention is to design a method for metallizing the surface of an optical fiber, which comprises plating a layer of Ni-P alloy on the surface of the optical fiber by chemical plating and then electroplating a layer of nickel by electroplating.

[0008] In order to achieve the above technical effects, the present invention is implemented through the following technical solutions: A method for metallizing the surface of an optical fiber, characterized in that it includes the following steps:

[0009] S1. Removal of protective layer and degreasing: Immerse the optical fiber in concentrated sulfuric acid to remove the protective layer, and use alkaline solution to treat grease and other dirt on the surface of the optical fiber; then use deionized water for ultrasonic cleaning;

[0010] S2, roughening: Use a strong acid solution containing hydrofluoric acid to weakly corrode the optical fiber surface, and then rinse thoroughly with deionized water;

[0011] S3, sensitization: Use sensitizing solution to sensitize the optical fiber surface for 6 to 10 minutes; make the optical fiber surface adsorb some easily oxidized substances to obtain sensitized optical fiber;

[0012] S4, activation: immerse the sensitized optical fiber in the activation liquid palladium chloride solution. At this time, the Sn on the surface of the optical fiber 2+ With Pd in ​​the activation solution 2+ The generated Pd atoms react and become the catalytic centers for chemical nickel plating to obtain pretreated optical fiber;

[0013] S5, chemical plating: using chemical plating method to deposit Ni-P alloy on the surface of pretreated optical fiber;

[0014] S6. Electroplating: The optical fiber after chemical plating is cleaned and dried with distilled water. The optical fiber is used as the cathode and the pure nickel tube is used as the anode. A protective layer is formed on the surface of the optical fiber based on the Ni-P alloy by electroplating.

[0015] Furthermore, in S1, the use of an alkaline solution to treat grease and other dirt on the surface of the optical fiber is specifically to immerse the optical fiber in a 30% sodium hydroxide solution at a temperature of 48-52°C for 19-21 minutes, and then rinse with deionized water 3-4 times.

[0016] Furthermore, in S3, the formula of the Minhua liquid is 10g of SnCl2·2H2O and 40ml of HCl in 1000ml of water.

[0017] Furthermore, in S5, depositing Ni-P alloy on the surface of the pretreated optical fiber by chemical plating specifically includes the following steps:

[0018] S5.1. The first plating solution comprises: 20-35 g / L NiSO4·6H2O, 10-15 g / L NaH2PO2·H2O, 24-28 ml / L H2NCH2CH2NH2, and 30-35 g / L H3BO3.

[0019] S5.2. Perform chemical plating: Place the pretreated optical fiber in the plating solution at a first plating solution temperature of 80-85°C for 30-90 minutes to perform chemical plating. An optical fiber with Ni-P alloy deposited on its surface can be obtained.

[0020] Furthermore, in S6, the method of forming a protective layer on the surface of the optical fiber based on the Ni-P alloy by electroplating specifically includes the following steps:

[0021] S6.1. The second plating solution consists of 160-200 g / L NiSO4·6H2O, 8-10 g / L NaCl, 28-36 g / L H3BO3, 50-70 g / L Na2SO4, and 0.06 g / L C2H 25 NaO4S;

[0022] S6.2. When the temperature of the second plating solution is 25-40°C, place the chemically plated optical fiber into the second plating solution for electroplating for 30-150 minutes.

[0023] Furthermore, the electroplating current density is 0.8-1.0A·dm -2 .

[0024] The beneficial effects of the present invention are:

[0025] (1) The pretreatment process of chemical plating does not require heat treatment. Electroplating nickel on the basis of chemical plating can avoid discontinuity or even shedding of the chemical plating layer;

[0026] (2) The present invention obtains a dense metal nickel coating on the surface of the optical fiber by chemical plating and electroplating, which can improve the mechanical reliability and high temperature resistance of the optical fiber;

[0027] (3) The raw materials used in the present invention are easily available, the operation is simple, and it is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a schematic flow chart of the method for metallizing the optical fiber surface according to the present invention;

[0030] Figure 2 SEM image of the optical fiber after chemical plating of the present invention;

[0031] Figure 3 SEM image of the optical fiber after electroplating of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Example 1

[0034] See Figure 1 It can be seen that a method for metallizing the surface of an optical fiber includes the following steps:

[0035] Step 1: Remove the protective layer and degrease: Immerse the optical fiber in concentrated sulfuric acid to remove the protective layer, then immerse the optical fiber in 30% sodium hydroxide solution at 48-52°C for 19-21 minutes, and then rinse with deionized water 3-4 times; then perform ultrasonic cleaning with deionized water;

[0036] Step 2: Roughening: Use a strong acid solution containing hydrofluoric acid to weakly corrode the optical fiber surface, and then rinse thoroughly with deionized water;

[0037] Step 3: Sensitization: Use a sensitizing solution containing 10g of SnCl2·2H2O and 40ml of HCl in 1000ml of water to sensitize the optical fiber surface for 6-10 minutes; some easily oxidizable substances are adsorbed on the optical fiber surface to obtain a sensitized optical fiber;

[0038] Step 4: Activation: Immerse the sensitized optical fiber in the activation solution of palladium chloride. At this time, the Sn on the surface of the optical fiber 2+ With Pd in ​​the activation solution 2+ The generated Pd atoms react and become the catalytic centers for chemical nickel plating to obtain pretreated optical fiber;

[0039] Step 5, chemical plating: depositing Ni-P alloy on the surface of the pretreated optical fiber by chemical plating; specifically comprising the following steps:

[0040] In S5, depositing Ni-P alloy on the surface of the pretreated optical fiber by chemical plating specifically includes the following steps:

[0041] S5.1. The first plating solution comprises: 20-35 g / L NiSO4·6H2O, 10-15 g / L NaH2PO2·H2O, 24-28 ml / L H2NCH2CH2NH2, and 30-35 g / L H3BO3.

[0042] S5.2. Perform chemical plating: Place the pretreated optical fiber in the plating solution at a first plating solution temperature of 80-85°C for 30-90 minutes to perform chemical plating. An optical fiber with Ni-P alloy deposited on its surface can be obtained.

[0043] Step 6: Electroplating: The optical fiber after chemical plating is washed with distilled water and dried, and a protective layer is formed on the surface of the optical fiber based on Ni-P alloy by electroplating with the optical fiber as the cathode and the pure nickel tube as the anode; the steps include:

[0044] S6.1. The second plating solution consists of 160-200 g / L NiSO4·6H2O, 8-10 g / L NaCl, 28-36 g / L H3BO3, 50-70 g / L Na2SO4, and 0.06 g / L C2H 25 NaO4S;

[0045] S6.2. When the temperature of the second plating solution is 25-40°C, place the chemically plated optical fiber into the second plating solution for electroplating for 30-150 minutes.

[0046] Example 2

[0047] Specifically, a process for chemical plating on the surface of optical fiber is carried out, and the steps are as follows:

[0048] Step 1: Remove the protective layer on the optical fiber surface → wash → degrease → wash → roughen → wash → sensitize → wash → activate → wash according to the steps of Example 1 to obtain a treated optical fiber;

[0049] Step 2: placing the treated optical fiber in a first plating solution at a temperature of 80°C for full reaction;

[0050] The first plating solution used in the process has the following formula: nickel chloride (NiSO4·6H2O) 22g / L; sodium hypophosphite (NaH2PO2·H2O) 15g / L; ethylenediamine (H2NCH2CH2NH2) 25ml / L; and H3BO3 30g / L. The resulting optical fiber has a Ni-P alloy deposited on its surface. A scanning electron microscope image of the optical fiber with the Ni-P alloy deposited on its surface is shown below. Figure 2 shown.

[0051] Example 3

[0052] The optical fiber with the Ni-P alloy deposited on the surface obtained in Example 2 was cleaned with distilled water and dried; then, the optical fiber with the Ni-P alloy deposited on the surface was used as the cathode and the pure nickel tube was used as the anode. Under the condition of the plating solution temperature of 25°C, the current density was 0.8A·dm -2 electroplating;

[0053] The second plating solution formula of electroplating is: NiSO4·6H2O 180g / L, NaCI 9g / L, H3BO3 32g / L, Na2SO460g / L, C2H 25 NaO4S 0.06g / L; after mixing, the pH value is 5.2. The photo of the optical fiber after electroplating is as follows Figure 3 shown.

Claims

1. A method for metallizing the surface of an optical fiber, characterized in that: The following steps are involved: S1. Removal of protective layer and degreasing: Immerse the optical fiber in concentrated sulfuric acid to remove the protective layer, and use alkaline solution to treat grease and other dirt on the surface of the optical fiber; then use deionized water for ultrasonic cleaning; S2, roughening: Use a strong acid solution containing hydrofluoric acid to weakly corrode the optical fiber surface, and then rinse thoroughly with deionized water; S3, Sensitization: Use sensitizing solution to sensitize the optical fiber surface for 6~10 minutes; The surface of the optical fiber is adsorbed with some easily oxidizable substances to obtain a sensitized optical fiber; S4, activation: immerse the sensitized optical fiber in the activation liquid palladium chloride solution. At this time, the Sn on the surface of the optical fiber 2+ With Pd in ​​the activation solution 2+ The generated Pd atoms react and become the catalytic centers for chemical nickel plating to obtain pretreated optical fiber; S5, chemical plating: using chemical plating method to deposit Ni-P alloy on the surface of pretreated optical fiber; S6. Electroplating: The optical fiber after chemical plating is cleaned and dried with distilled water. The optical fiber is used as the cathode and the pure nickel tube is used as the anode. A protective layer is formed on the surface of the optical fiber based on the Ni-P alloy by electroplating.

2. The method for metallizing the surface of an optical fiber according to claim 1, wherein: In S1, the use of an alkaline solution to treat grease and other dirt on the surface of the optical fiber is specifically to immerse the optical fiber in a 30% sodium hydroxide solution at a temperature of 48-52° C. for 19-21 minutes, and then rinse with deionized water 3-4 times.

3. The method for metallizing the surface of an optical fiber according to claim 1, wherein: In S3, the sensitizing solution is formulated as 1000 ml of water containing 10 g of SnCl2·2H2O and 40 ml of HCl.

4. The method for metallizing the surface of an optical fiber according to claim 1, wherein: In S5, depositing Ni-P alloy on the surface of the pretreated optical fiber by chemical plating specifically includes the following steps: S5.

1. The first plating solution comprises: 20-35 g / L NiSO4·6H2O, 10-15 g / L NaH2PO2·H2O, 24-28 ml / L H2NCH2CH2NH2, and 30-35 g / L H3BO3. S5.

2. Perform chemical plating: Place the pretreated optical fiber in the plating solution at a first plating solution temperature of 80-85°C for 30-90 minutes to perform chemical plating. An optical fiber with Ni-P alloy deposited on its surface can be obtained.

5. The method for metallizing the surface of an optical fiber according to claim 1, wherein: In S6, the method of forming a protective layer on the Ni-P alloy surface of the optical fiber by electroplating specifically includes the following steps: S6.

1. The second plating solution consists of 160-200 g / L NiSO4·6H2O, 8-10 g / L NaCl, 28-36 g / L H3BO3, 50-70 g / L Na2SO4, and 0.06 g / L C2H 25 NaO4S; S6.

2. When the temperature of the second plating solution is 25-40°C, place the chemically plated optical fiber into the second plating solution for electroplating for 30-150 minutes.

6. The method for metallizing the surface of an optical fiber according to claim 5, characterized in that: The current density of the electroplating is 0.8-1.0 A·dm -2 .

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