Uniform deposition device for PCVD (plasma chemical vapor deposition) process

Abstract

The utility model relates to a PCVD (plasma chemical vapor deposition) process uniform deposition device which comprises rotary sealing chucks coaxially and correspondingly arranged on two sides of a lathe bed, the rotary sealing chucks on the two sides are connected with a synchronous rotary driving device, and a microwave resonant cavity is arranged between the two rotary sealing chucks. The two rotary sealing chucks comprise a gas inlet rotary sealing chuck and a gas exhaust rotary sealing chuck, the gas inlet rotary sealing chuck is communicated with a raw material gas source through a gas inlet pipe, and the gas exhaust rotary sealing chuck is communicated with a vacuum pump gas pumping system through a gas exhaust pipe. And the auxiliary exhaust pipe is communicated with the auxiliary vacuum pump air extractor through a tandem electric control valve. The axial uniformity of PCVD (plasma chemical vapor deposition) process deposition can be effectively improved by increasing intermittent air exhaust, so that the effective rod length of a deposition core rod and the quality of a deposition liner tube are improved.

Description

Technical Field

[0001] The utility model relates to a PCVD process uniform deposition device, belonging to the technical field of optical fiber processing equipment. Background Art

[0002] In recent years, with the accelerated construction of 5G in China, the demand for optical fiber cables in the communication market is continuing to increase. As an indispensable part of 5G construction, optical fiber cables are playing an increasingly important role in 5G communication networks. Optical fiber is made by drawing preform rods, so preform rod manufacturing technology plays a very critical role in the production of optical fiber. The PCVD process in the preparation of optical fiber preform rods uses microwave plasma chemical vapor deposition method to carry out vapor deposition and high-temperature oxidation reaction in a high-purity quartz glass liner tube. The reaction gas is SiCl4, O2 and other small amounts of dopants. The heat source used for the reaction is a microwave source. Its reaction mechanism is that the pump end uses a variable frequency vacuum pump to ensure a constant low-pressure state. The microwave activates the gas to generate plasma to ionize the reaction gas. The ionized reaction gas is charged ions. The charged ions recombine to release heat energy to melt the gaseous reactants to form a transparent quartz glass deposition layer. Deposition is to use low-pressure plasma to make the gaseous chloride and oxygen flowing into the high-purity quartz glass tube directly deposited in the high-temperature reaction cavity into the optical fiber core glass layer required by the design. The advantages of the PCVD process are good parameter repeatability between core rod roots, high deposition reaction efficiency, precise control of refractive index distribution, and the ability to produce optical fibers with complex refractive index structure profiles. However, the disadvantages are low deposition rate, low amount of glass deposited per unit time, high purity requirements for the reaction gas raw materials, and very high purity requirements for the base quartz liner tube.

[0003] The PCVD process is achieved by depositing a quartz liner through a PCVD deposition device. In the actual deposition process of the PCVD process, the core diameter of the core rod is prone to bulging in the axial direction. The large core diameter makes the axial uniformity of the core rod worse, causing the core diameter to exceed the standard, resulting in a decrease in the quality of the deposited core rod and a reduction in the effective rod length, or even the scrapping of the core rod, thereby reducing the utilization rate of the PCVD process deposited liner and increasing the manufacturing cost of the PCVD process deposited core rod. Summary of the invention

[0004] The technical problem to be solved by the utility model is to provide a PCVD process uniform deposition device in view of the problems existing in the above-mentioned prior art, which can effectively improve the axial uniformity of PCVD process deposition, thereby increasing the effective rod length of the deposition core rod and the quality of the deposition liner.

[0005] The technical solution adopted by the utility model to solve the above-mentioned problems is:

[0006] It includes rotary sealing chucks coaxially arranged on both sides of the bed, the rotary sealing chucks on both sides are connected to a synchronous rotation driving device, a microwave resonance cavity is arranged between the two rotary sealing chucks, the microwave resonance cavity is connected to an axial reciprocating moving device, the microwave resonance cavity is arranged in a heat preservation furnace, the two rotary sealing chucks include an intake rotary sealing chuck and an exhaust rotary sealing chuck, the intake rotary sealing chuck is connected to a raw material gas source through an intake pipe, and the exhaust rotary sealing chuck is connected to a vacuum pump exhaust system through an exhaust pipe, and is characterized in that an auxiliary exhaust pipe is connected to the exhaust pipe, and the auxiliary exhaust pipe is connected to an auxiliary vacuum pump exhaust device through a series electric control valve.

[0007] According to the above scheme, the electrically controlled valve is an electrically controlled stop valve or an electrically controlled throttle valve.

[0008] According to the above scheme, the electric control end of the electric control valve is connected to the PLC control module.

[0009] According to the above scheme, the electrically controlled stop valve is periodically opened and closed as the resonance cavity reciprocates along the axial direction, so that the auxiliary exhaust pipe is periodically connected or disconnected with the auxiliary vacuum pump device.

[0010] According to the above scheme, the electronically controlled throttle valve periodically and intermittently increases and throttles the flow as the resonance cavity reciprocates along the axial direction, so that the conduction between the auxiliary exhaust pipe and the auxiliary vacuum pump device is periodically and intermittently enlarged or reduced.

[0011] The deposition process of the utility model is:

[0012] First, use a pure glass liner as the base tube, clamp it on the above PCVD deposition device, and close it. Auxiliary exhaust The tube is subjected to conventional PCVD deposition processing. After the processing is completed, the deposited liner tube is melted and shrunk into a solid core rod. The core layer of the solid core rod is tested to determine the core diameter deviation part along the axial direction in the core layer;

[0013] Input the relevant data and results of the test into the PLC control module for controlling the electronically controlled valve of the auxiliary exhaust pipe;

[0014] A pure glass liner is used as the base tube and clamped on the PCVD deposition device for PCVD deposition processing. At the same time, the auxiliary function of the PLC control module is started. Whenever the resonant cavity moves to the area with a larger core diameter, the PLC controls the electric control valve to connect the auxiliary vacuum pump exhaust device, so that the newly added vacuum pump exhaust device is connected to the exhaust pipe exhaust system, and an exhaust flow rate is increased to reduce the concentration of reactive gas deposited in the area with a larger core diameter. In other areas with normal deposition core diameter, the electric control valve is closed and deposition processing is carried out according to the normal operating state. This cycle is repeated until the deposition is completed.

[0015] According to the above scheme, the gas pressure in the glass liner is maintained at 5-40 mbar during deposition.

[0016] According to the above scheme, the specifications of the glass liner are: outer diameter 30-80 mm, single-side wall thickness 1.5-25 mm, and length 1.0-4.0 m.

[0017] According to the above scheme, the power of the resonant cavity during deposition is 1kw to 30kw.

[0018] According to the above scheme, the temperature of the insulation furnace during deposition ranges from 600 to 1800°C.

[0019] According to the above scheme, when the core diameter is larger, the difference value fluctuates within the range of 5 to 15 mm.

[0020] The beneficial effects of the utility model are as follows: 1. By connecting an auxiliary exhaust pipe, adding a vacuum pump system, and controlling the on and off of the electric control valve through PLC, when the resonant cavity moves to the area with a larger core diameter, increasing the short-term suction force can effectively reduce the concentration of the reaction gas in the gas end reaction area, reduce the amount of glass deposition, and reduce the existence of a larger core diameter, thereby improving the axial uniformity of the core rod, improving the effective rod length of the deposition core rod and the quality of the deposition liner, reducing the scrapping of the core rod, and increasing the production capacity of the core rod. 2. The utility model is not only simple and reasonable in structure, but also easy to control and operate, and the effect achieved is obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic structural diagram of an embodiment of the device of the utility model.

[0022] Figure 2 It is a comparison diagram of the core diameter distribution of the core rod of the utility model and the comparative example. DETAILED DESCRIPTION

[0023] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0024] The device of the utility model is as follows Figure 1As shown, it includes rotary sealing chucks coaxially arranged on both sides of the bed, the rotary sealing chucks on both sides are connected to the synchronous rotation driving device, a microwave resonant cavity 4 is arranged between the two rotary sealing chucks, the microwave resonant cavity is connected to the axial reciprocating moving device, the microwave resonant cavity is arranged in the heat preservation furnace 2, the glass liner 3 passes through the microwave resonant cavity and is placed in the heat preservation furnace 2, and the two ends of the glass liner are fixed and sealed by the rotary chucks, the two rotary sealing chucks include an intake rotary sealing chuck 1 and an exhaust rotary sealing chuck 5, the intake rotary sealing chuck is connected to the original through the intake pipe The exhaust rotary sealing chuck is connected to the vacuum pump exhaust system 7 through the exhaust pipe 6, the exhaust pipe is connected to an auxiliary exhaust pipe 8, the auxiliary exhaust pipe is connected to the auxiliary vacuum pump exhaust device 11 through the series electric control valve 9, the electric control end of the electric control valve is connected to the PLC control module 10, the electric control valve is an electric control stop valve, and the electric control stop valve is periodically opened and closed with the reciprocating movement of the resonance cavity along the axial direction, so that the auxiliary exhaust pipe is periodically connected or disconnected with the auxiliary vacuum pump device.

[0025] The deposition process and method of the utility model are as follows: firstly, a pure glass liner is used as a base tube, which is clamped on a PCVD deposition device, and the auxiliary exhaust pipe is closed to perform conventional PCVD deposition processing. The liner length is 2.5m, the wall thickness is 5mm, the outer diameter of the liner is 55mm, the working pressure is 22mbar, the power of the deposition core rod is 12.5Kw, and the actual furnace temperature of the insulation furnace during deposition is 995°C. After the processing is completed, the deposited liner is melted and shrunk into a solid core rod, and the core layer of the solid core rod is detected. In the core layer of the solid core rod, there is an obvious core diameter deviation portion A along the axial direction, and the maximum difference of the core diameter fluctuation is 5mm. Figure 2 As shown in Scheme 1. According to the detection situation, the relevant data and results of the detection are input into the PLC control module for the control of the auxiliary exhaust pipe electric control valve; then the pure glass liner with the same index is used as the base tube, clamped on the PCVD deposition device, and the PCVD deposition process is carried out under the same process conditions. At the same time, the auxiliary function of the PLC control module is started. Whenever the resonant cavity moves to the area with a larger core diameter, the PLC controls the electric control valve to connect the auxiliary vacuum pump exhaust device, so that the newly added vacuum pump exhaust device is connected to the exhaust pipe exhaust system, and an exhaust flow rate is added to reduce the concentration of the reaction gas deposited in the area with a larger core diameter. In other areas with normal deposition core diameters, the electric control valve is closed, and the deposition process is carried out according to the normal operating state, and this reciprocating cycle is repeated until the deposition is completed. The deposited liner is then melted and shrunk into a solid core rod, and the core layer of the modified solid core rod is tested. The maximum difference in the core diameter fluctuation in the core layer of the solid core rod in the axial core diameter deviation area A is 2mm, which has been significantly reduced and returned to the normal core diameter range. The axial uniformity of the core diameter of the core rod has been significantly improved, as shown in Figure 1. Figure 2 As shown in Scheme 2.

Claims

1. A PCVD process uniform deposition device, comprising rotary sealing chucks coaxially arranged on both sides of a bed, the rotary sealing chucks on both sides are connected to a synchronous rotation drive device, a microwave resonant cavity is arranged between the two rotary sealing chucks, the microwave resonant cavity is connected to an axial reciprocating moving device, the microwave resonant cavity is arranged in a heat preservation furnace, the two rotary sealing chucks include an intake rotary sealing chuck and an exhaust rotary sealing chuck, the intake rotary sealing chuck is connected to a raw material gas source through an intake pipe, and the exhaust rotary sealing chuck is connected to a vacuum pump exhaust system through an exhaust pipe, characterized in that The exhaust pipe is connected to an auxiliary exhaust pipe, and the auxiliary exhaust pipe is connected to an auxiliary vacuum pump exhaust device through a series electric control valve.

2. The PCVD process uniform deposition device according to claim 1, characterized in that The electric control end of the electric control valve is connected to the PLC control module.

3. The PCVD process uniform deposition device according to claim 1 or 2, characterized in that The electrically controlled valve is an electrically controlled stop valve or an electrically controlled throttle valve.

4. The PCVD process uniform deposition device according to claim 3, characterized in that The electrically controlled stop valve is periodically opened and closed as the resonance cavity reciprocates along the axial direction, so that the auxiliary exhaust pipe is periodically connected or disconnected with the auxiliary vacuum pump device.

5. The PCVD process uniform deposition device according to claim 3, characterized in that The electronically controlled throttle valve performs periodic intermittent flow increase and throttling as the resonance cavity reciprocates along the axial direction, so that the conduction between the auxiliary exhaust pipe and the auxiliary vacuum pump device is periodically intermittently enlarged or reduced.

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