Low-electric-loss three-proofing technology of microstrip antenna

Abstract

The invention discloses a low-electric-loss three-proofing process for a microstrip antenna, and belongs to the field of electronic processes. A coating film is deposited on the surface of a microstrip antenna printed board by adopting a plasma enhanced chemical vapor deposition technology; therefore, fluorine-containing micro-nano film layers which have good three-proofing protection performance and low electrical property loss at the same time are formed on the surface of the printed board step by step. A substrate of the microstrip antenna printed board is a tin-plated substrate, an acrylate composite material is selected as a micron-scale coating deposition material, a modified hydrophobic composite material is selected as a nano-scale coating material, and the total thickness of a deposition film layer is 3-5 microns. According to the invention, a uniform and complete fluorine-containing micro-nano film layer can be formed on the microstrip antenna printed board, and the film layer has better environmental adaptability and smaller telecommunication performance influence, and has important significance for actual protection of the microstrip antenna printed board.

Description

Technical Field

[0001] The invention belongs to the field of electronic technology. Background Art

[0002] Plasma-enhanced chemical vapor deposition technology mainly uses plasma discharge to clean and activate the product surface, and provides energy for the coating material molecules to open chemical bonds, promoting the polymerization reaction to continue. The excited electrons generated during the discharge process ionize the monomer molecules, and the monomer molecules split to produce free electrons, ions, excited molecules and free radicals. Under a vacuum environment, the free radicals undergo adsorption, condensation and polymerization reactions on the surface of the activated substrate. The electrons and ions cross-link and form chemical bonds with the deposited molecules, continuously polymerizing and growing to form a high-strength, dense micro-nano film layer. The designed plasma-enhanced chemical vapor deposition fluorine-containing film layer has the properties of being waterproof, moisture-proof, corrosion-resistant, mildew-resistant, and resistant to electrical breakdown.

[0003] At present, microstrip antenna printed circuit boards are often protected by spraying low-loss coatings or Parylene vapor deposition processes. The thickness of the low-loss coating film is generally 50μm-90μm, and the thickness of the Parylene film is generally 20μm-25μm. Low-loss coatings and Parylene film layers are easily roughened and peeled when applied to discontinuous areas on the surface of microstrip antennas. The fluorine-containing micro-nano film layer prepared step by step by plasma enhanced chemical vapor deposition technology can achieve better protection performance when the thickness is 5nm-10μm. The film layer has good bonding with the substrate, and the surface is uniform and continuous. At the same time, the thinner film layer thickness can also reduce the electrical performance loss of the microstrip antenna printed circuit board. Summary of the invention

[0004] In order to reduce the influence of the existing protection process on the telecommunication performance of the microstrip antenna printed circuit board, the present invention proposes a low-electrical-loss three-proofing process for the microstrip antenna. By using plasma-enhanced chemical vapor deposition technology, a fluorine-containing micro-nano film layer is prepared step by step for application in the three-proofing treatment of the microstrip antenna printed circuit board. After the three-proofing treatment of the microstrip antenna printed circuit board, the printed circuit board can have excellent telecommunication performance and environmental adaptability.

[0005] The technical solutions to achieve the purpose of the present invention include:

[0006] Plasma enhanced chemical vapor deposition is used to place a microstrip antenna printed circuit board into a coating vacuum chamber with a vacuum degree of 0.1 to 0.5 Pa. Inert gas is introduced into the vacuum chamber to generate plasma, and then the vaporized deposition material is introduced into the vacuum chamber for 360° conformal coating and deposition on the surface of the microstrip antenna printed circuit board, thereby forming a micro-nano polymer composite film on the antenna surface. The plasma enhanced chemical vapor deposition of the microstrip antenna printed circuit board is carried out in two steps. First, a layer of coating with a thickness of 2.5 to 4.5 μm is deposited on the surface of the printed circuit board. After curing, a layer of hydrophobic coating of about 100 to 500 nm is deposited on the surface of the coating. The total thickness of the deposited film layer is about 3 to 5 μm. The 2.5 to 4.5 μm coating deposition material is an acrylate composite material. The 100 to 500 nm coating material is a modified hydrophobic composite material.

[0007] Furthermore, the modified hydrophobic composite material mainly comprises silica particles modified by heptadecafluorodecyltriethoxysilane and a fluorocarbon resin composite material.

[0008] Furthermore, the microstrip antenna printed circuit board substrate is a tin-plated substrate.

[0009] Furthermore, in order to achieve 360° conformal coating, the microstrip antenna printed circuit board should be placed vertically, evenly and without obstruction in the coating cavity.

[0010] Compared with the prior art, the present invention has the following significant advantages:

[0011] The present invention is suitable for the three-proof protection of microstrip antenna printed circuit boards. The fluorine-containing micro-nano film layer prepared in steps using plasma enhanced chemical vapor deposition is thin, continuous, and relatively uniform. The film layer has less impact on the telecommunications performance of the antenna printed circuit board. At the same time, the fluorine-containing micro-nano film layer also has excellent environmental adaptability and bonding strength, which can meet the use requirements in long-term harsh environments. The acrylic coating prepared in the first step using plasma enhanced chemical vapor deposition has good bonding strength with the tin-plated substrate, and has certain corrosion resistance, moisture resistance, mildew resistance, and durability. The fluorine-containing hydrophobic film layer prepared in the second step has good hydrophobicity, and can have excellent waterproof, anti-icing, and self-cleaning properties.

[0012] The present invention is further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Process diagram of the present invention.

[0014] Figure 2 Microstrip antenna film thickness diagram.

[0015] Figure 3 Microstrip antenna hydrophobicity diagram. DETAILED DESCRIPTION

[0016] The existing microstrip antenna three-proof process has discontinuous surface coatings that are prone to roughness and peeling, and the film thickness is too thick, which affects the telecommunications performance of the microstrip antenna. The present invention provides a low-electrical-loss three-proof process for microstrip antennas. The fluorine-containing micro-nano film layer prepared step by step by plasma-enhanced chemical vapor deposition technology can achieve good protection performance when the thickness is 5nm-10μm. The film layer has good bonding strength with the substrate, and the surface is uniform and continuous. The thinner film thickness can also reduce the electrical performance loss of the microstrip antenna printed circuit board. The present invention is of great significance to the protection and application of microstrip antenna printed circuit boards.

[0017] In order to illustrate the technical solution and technical purpose of the present invention, the present invention is further introduced below in conjunction with the accompanying drawings and preferred embodiments.

[0018] Example: Figure 1 As shown, the low electrical loss three-proof process of a microstrip antenna of the present invention is: cleaning → local protection → plate swing → drying → plasma enhanced chemical vapor deposition → removal of local protection → inspection → coating result detection.

[0019] Preferably, the microstrip antenna printed circuit board uses a tin-plated substrate microstrip antenna printed circuit board, and the surface oil is cleaned using an ultrasonic cleaner. The connector part of the microstrip antenna printed circuit board is locally protected, and the local protection method uses glue dispensing and masking. The microstrip antenna plate should use a jig suitable for the product size, production requirements and protection needs to plate the product. The microstrip antenna printed circuit board should be placed vertically in the jig, evenly placed and without obstruction. After the microstrip antenna plate is completed, it is dried. The drying process of the microstrip antenna printed circuit board requires a relative humidity of 3% RH, a temperature of 25°C, and a drying time of 2h in a closed environment.

[0020] Preferably, the dried microstrip antenna printed circuit board is placed in a plasma enhanced vapor deposition instrument, the deposition chamber is evacuated and then the microstrip antenna printed circuit board is placed in a vacuum chamber with a vacuum degree of 0.5 Pa, helium is discharged into the vacuum chamber to generate plasma, and then the vaporized acrylic composite material is passed into the vacuum chamber for 360° conformal coating and deposited on the surface of the microstrip antenna printed circuit board, forming a film layer with a thickness of 4.5 μm on the surface of the microstrip antenna.

[0021] Preferably, helium is continuously introduced into the vacuum chamber, plasma is generated by discharge in a vacuum environment to induce the monomer material to break and polymerize, the surface of the microstrip antenna is activated, helium is continuously introduced, and then a modified hydrophobic composite material comprising silica particles modified with heptadecafluorodecyltriethoxysilane and a fluorocarbon resin composite material is deposited on the surface of the microstrip antenna printed circuit board by 360° conformal coating by vacuum vapor deposition, forming a hydrophobic film layer with a thickness of 500 nm on the surface of the microstrip antenna.

[0022] Preferably, after the coating is completed, the microstrip antenna is taken out of the vacuum chamber, and then the local protective adhesive at the surface connector of the microstrip antenna is removed. The adhesive used can be quickly separated from the surface of the printed circuit board and no adhesive remains on the surface of the printed circuit board. The microstrip antenna is extracted for slicing to check the film thickness and uniformity. The thickness error does not exceed ±0.2μm. Figure 2 As shown in the figure, the film layer is not allowed to be rough or have discontinuous areas. After the film thickness and uniformity inspection are completed, the hydrophobicity and other functional properties of the film layer are tested, such as Figure 3 shown.

[0023] Environmental adaptability performance analysis: The test verification results of the microstrip antenna after protection by this type of technical solution are shown in the following table:

[0024] Table 1 Product test table

[0025]

Claims

1. A low electrical loss three-proof process for a microstrip antenna, characterized by: Plasma-enhanced chemical vapor deposition is used to place the microstrip antenna printed circuit board into a coating vacuum chamber with a vacuum degree of 0.1-0.5 Pa. Inert gas is introduced into the vacuum chamber to generate plasma, and then the vaporized deposition material is introduced into the vacuum chamber for 360° conformal coating and deposition on the surface of the microstrip antenna printed circuit board, thereby forming a micro-nano-scale polymer composite film on the antenna surface. The plasma enhanced chemical vapor deposition of the microstrip antenna printed circuit board is carried out in two steps. First, a coating with a thickness of 2.5 to 4.5 μm is deposited on the surface of the printed circuit board. After curing, a hydrophobic coating with a thickness of about 100 to 500 nm is deposited on the surface of the coating. The total thickness of the deposited film layer is about 3 to 5 μm. The 2.5 to 4.5 μm coating deposition material is an acrylate composite material; the 100 to 500 nm coating material is a modified hydrophobic composite material.

2. The low electrical loss three-proof process of the microstrip antenna according to claim 1 is characterized in that: The modified hydrophobic composite material comprises silica particles modified by heptadecafluorodecyltriethoxysilane and a fluorocarbon resin composite material.

3. The low electrical loss three-proof process of the microstrip antenna according to claim 1 is characterized by: The substrate of the microstrip antenna printed circuit board is a tin-plated substrate.

4. The low electrical loss three-proof process of the microstrip antenna according to claim 1 is characterized in that: To achieve 360° conformal coating, the microstrip antenna printed circuit board should be placed vertically, evenly and without obstruction in the coating cavity.

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