A method for preparing a meltable polytetrafluoroethylene composite steel container or pipe

Abstract

A method for preparing a meltable polytetrafluoroethylene composite steel container or pipe, the characteristics of which are: it includes the following steps: first, making a steel container or pipe; second, making a meltable polytetrafluoroethylene liner matching the size of the steel container or pipe; third, making a stainless steel plate mesh matching the size of the inner wall of the steel container or pipe; fourth, using resistance welding to weld the stainless steel mesh to the inner wall of the steel container or pipe; fifth, using a pressurizing device to press the meltable polytetrafluoroethylene liner to the stainless steel plate mesh, and at the same time, by installing a heating device on the outside of the steel container or pipe, the stainless steel plate mesh is forced to melt into the meltable polytetrafluoroethylene liner; finally, the pressurizing device and the heating device are removed. The meltable polytetrafluoroethylene composite steel container or pipe prepared by the present invention can make the product cleanliness meet the electronic grade G5 level requirements, reduce the production cost by about 20%, and increase the vacuum resistance and bonding strength by more than 50% year-on-year.

Description

Technical Field

[0001] The invention relates to a semiconductor technology, in particular to a preparation technology of a container for holding or turnover used in the process of preparing semiconductor devices, specifically a preparation method of a meltable polytetrafluoroethylene composite steel container or pipeline. Background Art

[0002] As we all know, the high-purity wet electronic-grade chemicals required in the chip and semiconductor fields and the production equipment of wet electronic-grade chemicals have extremely stringent requirements on metal and other impurity ions; fusible polytetrafluoroethylene (PFA) has always been the preferred material for domestic and foreign industries.

[0003] At present, there are two ways to form fusible polytetrafluoroethylene (PFA) with steel containers and pipes in the industry:

[0004] Method 1: Use glue to paste. This method uses chemical glue to paste the fusible polytetrafluoroethylene (PFA) sheet and the steel container. The main problems with this forming method are: 1. The glue is easy to age, has a short service life, and the operating temperature is generally lower than 120 degrees; 2. Glue is a chemical product, which poses a great threat to the health of employees and the environment; the glue bonding strength is not high, and it cannot meet the use requirements when the equipment is in a vacuum condition; 3. The manufacturing cost is high, and the use of composite glue will greatly increase the equipment manufacturing cost; such as Figure 1 shown.

[0005] Method 2 is to use compression molding, which involves placing fusible polytetrafluoroethylene (PFA) particles in a mold inside a steel container, filling the mold with the particles, heating and melting them to form a composite with the shell. The main problems with this molding method are: 1. Cleanliness cannot be guaranteed, and the molten particles will bring impurity ions from the steel shell and tooling into the body; 2. The thickness of the molded fusible polytetrafluoroethylene (PFA) is relatively thick and cannot meet the vacuum resistance requirements of the equipment. The high thickness of the material makes the equipment very expensive; 3. At the same time, due to mold limitations, compression molding technology cannot be used to manufacture larger containers. Summary of the invention

[0006] The purpose of the present invention is to solve the problems that the existing fusible polytetrafluoroethylene (PFA) is insufficient in strength or the molded size is limited and the cleanliness cannot be effectively controlled when combined with a steel container or a pipe, and to invent a method for preparing a fusible polytetrafluoroethylene composite steel container or pipe with high connection strength and unlimited covering size.

[0007] The technical solution of the present invention is:

[0008] A method for preparing a meltable polytetrafluoroethylene composite steel container or pipe, the characteristics of which are: it comprises the following steps:

[0009] First, make a steel container or pipe;

[0010] Secondly, make a fusible PTFE liner that matches the size of the steel container or pipeline;

[0011] Third, make a stainless steel plate mesh that matches the size of the inner wall of the steel container or pipeline;

[0012] Fourth, the stainless steel mesh is welded to the inner wall of the steel container or pipeline by resistance welding;

[0013] Fifth, a pressurizing device is used to press the fusible polytetrafluoroethylene liner against the stainless steel plate mesh. At the same time, a heating device is installed on the outside of the steel container or pipeline to deform the fusible polytetrafluoroethylene liner due to heat, forcing the stainless steel plate mesh to melt into the fusible polytetrafluoroethylene liner, thereby achieving a high-strength combination of the fusible polytetrafluoroethylene liner and the inner wall of the steel container or pipeline;

[0014] Finally, remove the pressurizing device inside the steel container or pipeline and the heating device outside, and if necessary, remove the corresponding vacuum device.

[0015] Beneficial effects of the present invention:

[0016] The fusible polytetrafluoroethylene (PFA) composite steel container or pipe prepared by the present invention can promote the localization process of electronic-grade chemicals. The product cleanliness meets the electronic-grade G5 level requirements, reduces the production cost by about 20%, and increases the vacuum resistance and bonding strength by more than 50% year-on-year. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the existing process of preparing a meltable polytetrafluoroethylene composite steel container or pipeline.

[0018] Figure 2 Schematic diagram of the device for preparing the meltable polytetrafluoroethylene composite steel container or pipeline of the present invention.

[0019] Figure 3 It is a structural schematic diagram of the stainless steel plate of the present invention.

[0020] Figure 4 It is a schematic diagram of the connection between the stainless steel plate and the inner wall of the container or pipeline during the preparation process of the present invention.

[0021] Figure 5 It is a schematic diagram of the device for melting and covering the fusible polytetrafluoroethylene sheet and the steel container or pipeline of the present invention.

[0022] Figure 6It is a schematic diagram of a device for melting and covering a fusible polytetrafluoroethylene sheet with a large-sized (in height or length direction) steel container or pipeline of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example

[0024] like Figure 2-6 shown.

[0025] A method for preparing a meltable polytetrafluoroethylene composite steel container or pipe comprises the following steps:

[0026] First, a steel container (metal shell) or pipe 1 is manufactured; the steel container 1 here refers to a storage container with a cylindrical inner annular surface and only the annular surface is considered to be clad with relevant composite materials, and the processing technology of the flat bottom surface or top surface is the same as the prior art;

[0027] Secondly, a fusible polytetrafluoroethylene liner 2 matching the size of the steel container or pipeline is manufactured; the fusible polytetrafluoroethylene liner 2 should eventually be spliced ​​in multiple sections along the axial direction, and corresponding vacuum holes 7 are processed on the wall of the steel container or pipeline corresponding to the splicing position, such as Figure 2 , 4 Shown

[0028] Third, make a U-shaped stainless steel plate mesh 3 that matches the inner wall size of the steel container or pipeline 1, such as Figure 3 As shown; the thickness of the stainless steel plate mesh is 0.3-0.8mm, the mesh number is 3-10 (the aperture is 2-5mm).

[0029] Fourth, the stainless steel mesh is welded to the inner wall of the steel container or pipe by resistance welding (resistance welding point 8); and the aforementioned vacuum hole 7 is connected to the vacuum device 6 (through the vacuum joint 5) so that the fusible polytetrafluoroethylene liner can be welded while vacuuming, thereby improving the welding quality.

[0030] Fifth, a pressurizing device 9 (such as a hydraulic device) is used to press the fusible polytetrafluoroethylene liner 2 toward the inner wall of the steel container or pipeline 1 toward the stainless steel plate mesh 3 (the stainless steel plate mesh has a certain strength and will gradually embed into the fusible polytetrafluoroethylene liner), and at the same time, a heating device 10 (a high-frequency heating device can be used) is installed on the outside of the steel container or pipeline. The temperature generated by the heating device 10 should be such that the temperature transmitted to the fusible polytetrafluoroethylene liner can cause the fusible polytetrafluoroethylene liner to undergo plastic deformation, so that the stainless steel mesh can be embedded in the fusible polytetrafluoroethylene liner, thereby achieving a high-strength combination of the fusible polytetrafluoroethylene liner and the inner wall of the steel container or pipeline; Figure 5 shown.

[0031] Sixth, after all the sections of the fusible polytetrafluoroethylene lining plates are combined with the stainless steel plate mesh and attached to the wall of the steel container or pipeline, the vacuum device 6 is started, and the adjacent fusible polytetrafluoroethylene lining plates are welded together (forming the lining weld 4) while vacuuming using the existing welding technology, so as to obtain a steel container or pipeline with a complete inner wall covered with the fusible polytetrafluoroethylene lining plate, such as Figure 6 As shown, after the vacuuming is completed, the vacuuming hole can be used as a high negative pressure container, and a vacuum pump group is connected to the outside to form a true hole, so that the PFA lining and the steel layer are always in a close fit.

[0032] Finally, remove the pressurizing device inside the steel container or pipeline and the heating device outside to complete the subsequent processing of the bottom or top of the steel container or pipeline. Example

[0033] The difference between this example and the first embodiment is that due to the shorter axial length of the steel container or pipeline, a single fusible polytetrafluoroethylene liner can meet the demand, so the step of processing the vacuum hole on the steel container or pipeline can be omitted, and the work of the sixth step can be omitted. The rest is the same as the first embodiment.

[0034] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

Claims

1. A method for preparing a meltable polytetrafluoroethylene composite steel container or pipe, which comprises the following steps: First, make a steel container or pipe; Secondly, make a fusible PTFE liner that matches the size of the steel container or pipeline; Third, make a stainless steel plate mesh that matches the size of the inner wall of the steel container or pipeline; Fourth, the stainless steel mesh is welded to the inner wall of the steel container or pipeline by resistance welding; Fifth, a pressurizing device is used to press the fusible polytetrafluoroethylene liner against the stainless steel plate mesh. At the same time, a heating device is installed on the outside of the steel container or pipeline to deform the fusible polytetrafluoroethylene liner due to heat, forcing the stainless steel plate mesh to melt into the fusible polytetrafluoroethylene liner, thereby achieving a high-strength combination of the fusible polytetrafluoroethylene liner and the inner wall of the steel container or pipeline; Finally, remove the pressurizing device inside the steel container or pipeline and the heating device outside; The stainless steel plate mesh has a U-shaped structure, a thickness of 0.3-0.8 mm, and a mesh number of 3-10; When the axial length of the steel container or pipeline is greater than the axial length of the fusible polytetrafluoroethylene liner, multiple fusible polytetrafluoroethylene liners are used for axial splicing. At this time, radial vacuum holes should be drilled on the steel container or pipeline at the splicing point, and the vacuum holes should be connected to the vacuum device to facilitate the welding of the fusible polytetrafluoroethylene liner while vacuuming, thereby improving the welding quality and adhesion.

2. The method according to claim 1, characterized in that: The pressurizing device is a hydraulic device.

3. The method according to claim 1, characterized in that: The heating device is a high-frequency heating component.

Images