A circuit board for a power supply device for a severe environment and a method of manufacturing the same

Abstract

The application belongs to the technical field of power supply for marine engineering, and particularly relates to a power supply equipment circuit board for harsh environment and a preparation method thereof. The power supply equipment circuit board for harsh environment is obtained by sequentially plating N layers of films on the surface of the circuit board, wherein N is a positive integer greater than or equal to 2, film layer 1 is in direct contact with the circuit board, and the film layer 1 is one of a silicon dioxide film layer, an aluminum oxide film layer, a silicon nitride film layer, a titanium dioxide film layer and an aluminum nitride film layer. The application can provide reliable protection for the circuit board and electronic components thereon, so as to better cope with the use in harsh environments such as the sea.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power supply for ocean engineering, and particularly relates to a power supply equipment circuit board for harsh environment and a preparation method thereof. BACKGROUND

[0002] For special power supply for ocean engineering, how to realize stable and reliable operation is a key factor for its development. However, due to the high humidity, high salinity and extreme temperature change of the marine environment, the reliability requirement of the power supply equipment for ocean engineering is particularly high, which is different from that of the conventional power supply product. The circuit board contains the most core chips and circuit components of the power supply system, and is exposed to the environment, which is the most fragile core component of the power supply system for ocean engineering. How to ensure the stability of the PCB board is the key to ensuring the reliability of the special power supply equipment for ocean engineering.

[0003] The marine environment poses a great threat to the performance and service life of the circuit board, and can accelerate its aging and failure. In order to protect the circuit board from the influence of these harsh environments, three-proofing protection technology emerges as the times require, aiming to improve the reliability and durability of the circuit board. The three-proofing protection technology of the circuit board of the power supply device for ocean engineering mainly aims at the problems of moisture-proof, salt mist-proof and mildew-proof of the circuit board in the marine environment. At present, the status of three-proofing protection technology includes using various materials to coat the circuit board to form a protective layer. These materials include acrylic resin (AR), modified epoxy resin (ER), silicone resin (SR), polyurethane resin (UR) and parylene (XY), etc. For example, Chinese patent application CN210432038U discloses a circuit board coated with three-proofing paint, which comprises a printed circuit board, and a protective film layer formed after the three-proofing paint is coated on the printed circuit board and solidified, characterized in that a through hole penetrating the printed circuit board is arranged on the printed circuit board, and a columnar structure formed after the three-proofing paint is solidified is arranged in the through hole; the through hole is located in the coverage range of the protective film layer, and the columnar structure is connected with the protective film layer. In addition, there are also direct encapsulation of silicone glue, epoxy resin glue, etc., which completely encapsulate the circuit board. Although this method can improve the comprehensiveness and reliability of protection to a certain extent, it is inevitable that the moisture and heat resistance of the circuit board will be reduced, the overall cost will be increased, and the difficulty of maintenance and inspection will be greatly increased.

[0004] Overall, although the prior art adopts the above technical solutions, it is still difficult to meet the needs of the industry for long-term reliable operation of the power supply for ocean engineering, such as the application of some unattended areas, tropical extreme areas, immersion environments, etc. Moreover, due to the insufficient reliability of the prior art, the maintenance cycle of the power supply equipment is shorter, the use cost is increased, and the application development of the industry is restricted. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application aims to provide a power supply equipment circuit board for harsh environments and a preparation method thereof. The present application can provide more reliable protection for the circuit board and the electronic components thereon, so as to better cope with the use in harsh environments such as the sea.

[0006] The technical scheme of the present application is:

[0007] A preparation method of a power supply equipment circuit board for harsh environments, wherein N layers of films are sequentially plated on the surface of the circuit board to obtain the power supply equipment circuit board for harsh environments, N is a positive integer greater than or equal to 2, film layer 1 is in direct contact with the circuit board, and the film layer 1 is one of a silicon dioxide film layer, an aluminum oxide film layer, a silicon nitride film layer, a titanium dioxide film layer, and an aluminum nitride film layer.

[0008] Further, when N>2, film layer 2-film layer (N-1) are respectively one of an aluminum oxide film layer, a silicon nitride film layer, a titanium dioxide film layer, and an aluminum nitride film layer; and film layer N is one of an acrylic resin three-protection paint film layer, a modified epoxy resin three-protection paint film layer, a silicone resin three-protection paint film layer, a polyurethane resin three-protection paint film layer, and a poly-p-xylylene three-protection paint film layer.

[0009] Further, the thickness of the film layer 1 is 20-100 nm, and the thickness of the film layer N is 500-1500 m; when N>2, the thickness of the film layer 2-film layer (N-1) is 100-500 nm.

[0010] Further, the preparation method of the power supply equipment circuit board for harsh environments comprises the following steps:

[0011] S1: feeding the circuit board into an atmosphere-vacuum isolation buffer chamber, vacuumizing, and then feeding the circuit board into a buffer pretreatment+gas vacuum flushing chamber;

[0012] S2: vacuumizing the buffer pretreatment+gas vacuum flushing chamber, pre-cleaning and dynamic air jet flushing cleaning the circuit board with gas, and vacuumizing after the cleaning is completed;

[0013] S3: feeding the circuit board after the cleaning treatment into a glow discharge cleaning chamber, and cleaning the circuit board with working gas;

[0014] S4: feeding the treated circuit board into a film plating chamber provided with target material, and plating films by vacuum plating process to sputter the first to the N-1 layers of films;

[0015] S5: feeding the circuit board with plated films obtained in step S4 into a buffer chamber and a vacuum-atmosphere isolation buffer chamber in sequence, and then spraying the Nth layer of film after the circuit board is fed out.

[0016] Further, the step S1 is vacuumized to 1-10 Pa; the step S2 is vacuumized to 1*10-3 Pa-5*10-3 Pa; the gas in the step S2 is argon or nitrogen; the working gas in the step S3 is argon or nitrogen.

[0017] Further, the specific operation of the step S2 is: the gas with the pressure of 0.1-0.5 bar is introduced, the gas flow is 5-10 L / min during the pre-cleaning, and the pre-cleaning time is 10 s-1 min; during the dynamic jet washing in the step S2, the motor drives the exhaust pipe to move, the travel speed of the exhaust pipe is 0.1-0.3 m / s; the gas jetting is controlled, the gas pressure is 0.5-2.0 bar, and the spraying time is 2-10 minutes.

[0018] The application can improve the cleanliness of the circuit board before vacuum coating, improve the quality of subsequent coating, and reduce secondary pollution in the transmission and transportation process after conventional liquid cleaning by the synergistic effect of dynamic jet washing and vacuum environment, and is suitable for the production characteristics of the industry.

[0019] The step of dynamic jet washing of the circuit board is carried out in the buffer pretreatment + gas vacuum flushing chamber, the buffer pretreatment + gas vacuum flushing chamber is a vacuum box body, the dynamic exhaust pipe is designed in the vacuum box body, the exhaust pipe is driven to move up and down reciprocally by the motor, the high-pressure gas (such as nitrogen and argon) is uniformly sprayed on the surface of the workpiece by the combination of the uniformly distributed small hole jetting, more uniform cleaning coverage is realized, the cleaning efficiency is improved by the combination of the airflow shear force and the low resistance characteristics in the vacuum environment and the high-pressure gas spraying, the cleaning effect is improved, the gas consumption is reduced, the pollutants such as particles and grease are efficiently removed, the efficient and comprehensive cleaning of the workpiece is realized, and the basis for improving the quality of subsequent coating is laid.

[0020] For the circuit board just finished patch reflow soldering production, usually will carry out cleaning treatment, to remove the residue of soldering process: such as welding slag, flux and other substances, avoid the future cause circuit short circuit, open circuit, affect the power and transmission. Also to remove the possible left in the processing of acid, base, organic matter and other chemical pollution circuit board, if not cleaned in time, will corrode the circuit board, affect its conductivity and service life. The prior art will generally adopt manual chemical cleaning or ultrasonic cleaning method, after cleaning still need to carry out drying to guarantee the performance of the circuit board. Vacuum coating process has high requirement for the cleanliness of the substrate, which is in significant contradiction with the current PCBA production environment. In the field of power product manufacturing, the circuit board patch workshop generally adopts 100,000 level clean standard, and some enterprises even lack basic clean workshop. This production environment leads to the secondary attachment of dust, particulate matter and hair pollutants in the drying and transportation process of the cleaned circuit board. Especially for the PCBA board that needs vacuum coating treatment, these micron-level pollutants will seriously affect the uniformity and bonding strength of the coating layer, directly leading to the fluctuation of product qualification rate. In view of this industry pain point, the application innovatively introduces dynamic air jet flushing cleaning technology, which effectively removes the residual pollutants on the surface of the circuit board through physical flushing under the existing production environment conditions, successfully solving the quality hidden danger caused by insufficient environmental cleanliness in the traditional process.

[0021] Further, the vacuum coating process in step S4 is one of a magnetron sputtering method, a chemical vapor deposition method, a molecular beam epitaxy method and an atomic layer deposition method.

[0022] The circuit board of the prior art still leads to the failure of the circuit board in a harsh environment after adopting the film layer of three-proofing materials such as acrylic resin (AR), modified epoxy resin (ER), silicone resin (SR), polyurethane resin (UR) and parylene (XY) or adopting potting glue for sealing. The application adopts a vacuum coating process to prepare a bottom film layer directly contacting the circuit board, and through controlling the parameter conditions in the vacuum coating process, the growth of the thin film is more dense, the formation of the failure center is avoided, and the circuit board and the electronic components thereon are provided with more reliable protection, so that the use in a harsh environment such as the sea can be better coped with. The circuit board sealing and protecting film layer composed of the composite film system cooperates between the film systems to achieve excellent protection effect.

[0023] Further, the vacuum coating process is a magnetron sputtering method, and the magnetron sputtering reaction pressure is 0.5-1 Pa.

[0024] Further, the temperature of the buffer pretreatment + gas vacuum flushing chamber, the glow discharge cleaning chamber and the coating chamber is 50-80 DEG C; in step S5:

[0025] The buffer chamber is a high-vacuum environment, and the pressure of the high vacuum is 1*10-3 Pa to 5*10-3 Pa.

[0026] In the process of entering the vacuum-atmosphere isolation buffer chamber of the circuit board plated with the film obtained in step S4, the vacuum-atmosphere isolation buffer chamber is a low-vacuum environment, and the pressure of the low vacuum is 1 to 10 Pa, and when entering, the valve of the vacuum-atmosphere isolation buffer chamber is closed, and the atmosphere is filled to restore the pressure in the vacuum-atmosphere isolation buffer chamber to the atmospheric pressure level.

[0027] Another purpose of the present application is to provide the harsh environment power equipment circuit board prepared by the preparation method of the harsh environment power equipment circuit board.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) The harsh environment power equipment circuit board provided by the present application is composed of a circuit board and a plurality of film superimposed, and the composite film layer can better protect the circuit board.

[0030] (2) The harsh environment power equipment circuit board provided by the present application can provide more reliable protection for the circuit board and the electronic components thereon, so as to better cope with the use in harsh environments such as the sea. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structure exploded view of the harsh environment power equipment circuit board of the present application;

[0032] Figure 2 It is a flowchart of preparing the harsh environment power equipment circuit board by using the linear array continuous multi-chamber magnetron sputtering equipment in the embodiment 1-3 of the present application;

[0033] Figure 3 It is a structure schematic diagram of the linear array continuous multi-chamber magnetron sputtering equipment;

[0034] Figure 4 It is a longitudinal section schematic diagram of the 2# chamber vacuum cleaning chamber box;

[0035] Figure 5 It is another longitudinal section schematic diagram of the 2# chamber vacuum cleaning chamber box;

[0036] Figure 6 It is a principle schematic diagram of cleaning the circuit board;

[0037] Figure 7 It is a structure schematic diagram of the harsh environment power equipment circuit board in the embodiment 1-3 of the present application.

[0038] In the diagram, 11. Circuit board; 1. Membrane 1; 2. Membrane 2; 3. Membrane 3; N. Membrane N; 4. Inlet port connector for the cavity; 5. Vacuum cavity wall; 6. Exhaust pipe; 7. Outlet port; 8. Bellows; 9. Inlet port; 10. Inlet pipe; 12. MFC mass flow meter; 13. Motor; 14. Cam linkage mechanism; 15. Slide rod; 16. Magnetohydrodynamic seal; 17. Pin sleeve. Detailed Implementation

[0039] The present invention will be further described below through specific embodiments, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0040] An exploded view of the circuit board for the power supply equipment in harsh environments of this invention is shown below. Figure 1 As shown, the circuit board for power supply equipment in harsh environments of this invention is composed of a circuit board and a multilayer film, with the composite film layer providing better protection for the circuit board.

[0041] In this invention, different materials are used for different film layers to achieve diverse functions, enhance protective performance, and meet the protection requirements of circuit boards. However, all layers require the selection of materials with good insulation and thermal conductivity, and should be as robust as possible while maintaining good light transmittance. Specifically:

[0042] For example Figure 1 As shown, for film layer 1 (i.e. the film layer that is in direct contact with the circuit board), the present invention uses a material with extremely high chemical stability and excellent corrosion resistance, such as silicon dioxide (SiO2) film, which can avoid the exposure of fragile capacitor components on the circuit board to high temperature environment during the film preparation process, thus preventing premature performance degradation.

[0043] For film layers 2 to N, other film layers that can improve the characteristics of film layer 1 can be selected to form a film system with more comprehensive performance in all aspects. For example, alumina (Al2O3) film, silicon nitride (Si3N4) film, titanium dioxide (TiO2) film, aluminum nitride, etc.

[0044] For the topmost first layer, that is Figure 1 The Nth layer is coated with traditional three-proof materials, such as acrylic resin (AR), modified epoxy resin (ER), silicone resin (SR), polyurethane resin (UR), and parylene (XY).

[0045] Furthermore, after completing the construction of the above film system, for applications with particularly high reliability requirements, traditional potting and sealing methods can be used to pot the entire circuit board with the composite film system using potting materials such as silicone, forming a more reliable sealing system.

[0046] Embodiment 1, a method for manufacturing a power supply equipment circuit board for harsh environment

[0047] The method for manufacturing the power supply equipment circuit board for harsh environment comprises sequentially plating three layers of films on the surface of the circuit board to obtain the power supply equipment circuit board for harsh environment, wherein the film layer 1 is in direct contact with the circuit board, the film layer 1 is a silicon dioxide film layer, and the thickness of the film layer 1 is 20 nm; the film layer 2 is an aluminum oxide film layer, and the thickness of the film layer 2 is 500 nm; and the film layer 3 is a polyurethane resin three-protection paint film layer at the top layer, and the thickness of the film layer 3 is 500 microns.

[0048] The flowchart of the method for manufacturing the power supply equipment circuit board for harsh environment by the linear array continuous multi-chamber magnetron sputtering equipment in Embodiment 1 of the present application is shown in Figure 2 .

[0049] The structural diagram of the linear array continuous multi-chamber magnetron sputtering equipment is shown in Figure 3 , wherein:

[0050] (1) Each chamber is closed and isolated from each other by airtight valves to ensure independence and no air leakage between them;

[0051] (2) The 1# chamber is an atmospheric-vacuum isolation buffer chamber (equipment inlet buffer chamber), which continuously performs air charging and air pumping, and constantly switches between a low vacuum state (1-10 Pa) and a normal pressure state, so that the circuit board to be plated can enter the plating equipment from the outside;

[0052] (3) The 2# chamber is a buffer pretreatment + gas vacuum flushing chamber, which is usually in a high vacuum state (10 -3 Pa), and is used for entering the circuit board to be plated into a high vacuum state from a low vacuum chamber, and simultaneously performing appropriate heating treatment (50℃) on the circuit board to improve the film layer film forming quality;

[0053] (4) The 2#-5# chambers are all provided with heating devices, so that the circuit board to be plated can be kept at a required temperature (50℃);

[0054] (5) The 3# chamber is an Ar gas glow discharge cleaning chamber, high-purity argon (Ar) is introduced into the chamber to maintain the pressure in the chamber within a certain range, generally 0.1-1 Pa (this pressure range can ensure the stable formation of subsequent glow discharge);

[0055] (6) The 4# chamber is a film plating chamber 1 (sputtering SiO2 film), which is provided with a SiO2 target material, and is used for magnetron sputtering reaction and sputtering SiO2 film, and this chamber is in a high vacuum state (10 -3 Pa) for a long time;

[0056] (7) Chamber #5 is coating chamber 2 (for sputtering Al2O3 thin film), containing an Al2O3 target for magnetron sputtering reaction to sputter Al2O3 thin film. This chamber is under high vacuum for a long time (10 -3 Pa);

[0057] (8) Chamber #6 is a buffer chamber, which is usually in a high vacuum state (10 -3 Pa) is used as a buffer to move the coated circuit board from the high vacuum chamber to the low vacuum state, so as to ensure the high vacuum purity of reaction chambers 4# and 5# and prevent contamination from causing a decrease in film quality.

[0058] (9) Chamber #7 is an atmospheric-vacuum isolation buffer chamber (equipment outlet chamber). It is constantly filled and evacuated, switching between low vacuum (1-10Pa) and normal pressure so that the coated circuit board can switch from high vacuum chamber to low vacuum state and enter normal pressure state before being sent out of the equipment.

[0059] The specific manufacturing steps for the power supply circuit board used in harsh environments are as follows:

[0060] Before production began, the magnetron sputtering equipment was evacuated to a vacuum state using a vacuum pump. Chambers 1, 3, and 7 were in a low vacuum state (1-10 Pa), while chambers 2, 4, 5, and 6 were in a high vacuum state (10 Pa). -3 Pa).

[0061] Step 1: Perform a simple dust removal process on the circuit board to be coated to ensure that there is little dust or debris on the circuit board before it enters the vacuum coating equipment.

[0062] Step 2: As above Figure 3 As shown, at this time, the vent valve of chamber 1 of the magnetron sputtering equipment is opened to introduce atmospheric air into the chamber, so that it reaches the atmospheric pressure level. Since the pressure of chamber 1 and the outside is the same at this time, valve A is opened and the circuit board to be coated is sent into chamber 1 through the conveyor belt. Then valve A is closed.

[0063] Step 3: As above Figure 3 As shown, after the circuit board to be coated is sent into the sealed chamber 1, the chamber 1 is evacuated to a low vacuum state (1-10Pa). At this time, the pressure difference between chamber 1 and chamber 2 (high vacuum state) is very small. Valve B is opened, and the circuit board to be coated is sent into chamber 2 through the conveyor belt. Valve B is closed, so that chamber 2 is restored to a high vacuum state.

[0064] Step 4: Chamber #2 is a buffer pretreatment + gas vacuum rinsing chamber (vacuum cleaning chamber housing). A longitudinal sectional view of the vacuum cleaning chamber housing of Chamber #2 is shown below. Figure 4As shown, another longitudinal section view of the 2# chamber vacuum cleaning chamber box is shown as Figure 5 As shown. 2# chamber includes a box, the box is provided with a cavity inlet hole joint 4, the box is provided with a vacuum cavity wall 5, the vacuum cavity wall is provided with an exhaust pipe 6, the exhaust pipe 6 is provided with uniformly distributed exhaust hole 7, the middle section of the exhaust pipe 6 and the cavity inlet hole joint 4 are connected by the metal bellows 8 with good expansion performance, the box is provided with the air inlet 9 communicated with the vacuum cavity wall 5, the vacuum cavity wall 5 and the air inlet 9 are connected by the air inlet pipe 10, the air inlet pipe 10 is provided with MFC mass flow meter 12, the air inlet 9 and the exhaust pipe 6 are connected by the bellows 8, the air inlet pipe 10 and the bellows 8 are connected by the cavity inlet hole joint 4, the box is provided with the motor 13, the box is provided with the cam link mechanism 14, the rotating shaft of the motor 13 adopts the magnetic fluid sealing 16, the air inlet 9 and the exhaust pipe 6 of the vacuum chamber are connected by the bellows 8, so that the exhaust pipe 6 can move up and down, the cam link mechanism 14 is driven by the motor 13 to drive the exhaust pipe 6 to move vertically up and down, the exhaust pipe 6 is provided with two slide rods 15, the slide rod 15 is sleeved in the pin sleeve 17 fixed on the inner wall of the vacuum box, which ensures that the exhaust pipe 6 can move vertically on the plane where the two pin sleeves 17 are located when moving up and down, and will not swing randomly. The metal bellows with good expansion performance connected between the cavity inlet hole joint and the exhaust pipe in the cavity can meet the requirements of up and down reciprocating motion, the air inlet and the exhaust pipe of the vacuum chamber are connected by the bellows, so that the exhaust pipe can move up and down, and the exhaust pipe moves up and down by the motor. The 2# chamber is provided with a heater (not shown in the figure), which can preheat the entering circuit board to be plated to gradually reach a temperature of 50 DEG C, so as to facilitate high quality sputtering film forming.

[0065] The circuit board is pretreated, including the steps of vacuumizing and prewashing in the 2# chamber, dynamic jet washing, and the steps of washing in the 3# argon glow discharge cleaning chamber, wherein the specific steps of processing in the 2# chamber are as follows:

[0066] The 2# chamber is pumped to high vacuum degree (1x10-3Pa), the circuit board to be plated is prewashed in the 2# chamber, low pressure argon Ar (0.1-0.5bar) is sprayed to remove loose contaminants, the prewashing gas flow is 5L / min, the prewashing time is 10min; the circuit board is dynamically jet washed, which specifically includes 1) motor driven exhaust pipe movement: movement parameters: stroke range 200mm, exhaust pipe stroke speed 0.1m / s, 2) gas injection control: gas pressure: 0.5bar, spraying time: 2 minutes, 3) vacuum dynamic balance: the pressure is monitored in real time by the vacuum gauge, the air inlet valve and the pump speed are adjusted, and the vacuum degree fluctuation is maintained to be less than or equal to ±5%;

[0067] The schematic diagram of the principle of cleaning the circuit board is as followsFigure 6 As shown, cleaning is carried out in a low vacuum environment, using high-purity Ar gas, the gas from the gas inlet into the gas inlet pipe, through the gas inlet pipe to the exhaust pipe to spray, placed in the middle of the circuit board washing, through the bellows connecting the vacuum chamber gas inlet and exhaust pipe to achieve the exhaust pipe can move up and down, and then use the motor driven exhaust pipe, drive its up and down reciprocating movement, to achieve the surface of the circuit board gas spray, remove possible impurities.

[0068] After the end of the flushing, close the inlet valve, the vacuum pump to the chamber to high vacuum state (to 10-3Pa order) ;

[0069] Step 5: as shown in Figure 3 , open the C valve, the circuit board to be plated into the 3 # argon glow discharge cleaning chamber, using argon Ar glow discharge plasma cleaning, cleaning time control in 3 min; through the high-energy argon ion impact workpiece surface of the contaminant molecules, so that they from the workpiece surface. For organic contaminants, such as oil, photoresist, etc., the argon ion bombardment can be broken down into small molecular fragments, and then these fragments will be pumped away. For inorganic contaminants, such as metal oxides, dust particles, etc., argon ions can be knocked off from the surface. Through the glow discharge plasma cleaning further improve the degree of cleanliness of the circuit board, improve the quality of the subsequent film;

[0070] Step 6: open the D valve, through the conveyor belt to be plated into the 4 # chamber circuit board, then close the D valve, here is equipped with SiO2 target, at this time into the inert gas (argon Ar) to the chamber, when the reaction pressure reaches 0.5-1Pa, open the power supply to the target excitation glow, start SiO2 target sputtering, and film on the surface of the circuit board, sputtering power density control in 3W / cm 2 . Due to the need to maintain vacuum and stable reaction pressure, as well as the sputtering process itself consumption, argon is constantly reduced, the need to continue in the reaction process into the argon, this is adjusted by flow meter control. Here you can add film thickness meter to measure the thickness of the SiO2 film generated on the circuit board, when the film reaches the predetermined thickness (20nm) can be closed sputtering, close the argon flow into, to high vacuum state.

[0071] Step 7: when the 4 # chamber SiO2 film sputtering and pumping to restore to high vacuum state, open the E valve, through the conveyor belt to be plated into the 5 # chamber circuit board, then close the E valve, here is equipped with Al2O3 target, at this time into the inert gas (argon Ar) to the chamber, when the reaction pressure reaches 0.5-1Pa, open the power supply to the target excitation glow, start Al2O3 target sputtering, and film on the surface of the circuit board, sputtering power density control in 6W / cm 2The argon gas is continuously reduced due to the maintenance of vacuum and stable reaction pressure, and the consumption of sputtering process itself, and needs to be continuously input during the reaction process, which is adjusted and controlled by the flow meter. The thickness of the Al2O3 film generated on the circuit board can be measured by adding a film thickness meter, and the sputtering can be turned off when the film reaches the predetermined thickness (500 nm), and the argon flow is turned off and pumped to a high vacuum state.

[0072] Step 8: After the Al2O3 film in the 5# chamber is made and restored to a high vacuum state, the F valve is opened, and the plated film circuit board is sent into the high vacuum 6# buffer chamber through the conveying belt. The F valve is closed.

[0073] Step 9: The G valve is opened, and the circuit board is sent into the 7# chamber (vacuum-atmosphere isolation buffer chamber) in a low vacuum state. The G valve is closed, and the chamber is filled with atmosphere, so that the pressure in the 7# chamber is restored to atmospheric pressure. At this time, the 7# chamber and the external environment are both at atmospheric pressure, and there is no pressure difference, the H valve is opened, and the plated film circuit board is sent out through the conveying belt, and the process of magnetron sputtering and sputtering SiO2 film and Al2O3 film is completed.

[0074] Step 10: The plated film circuit board is taken out and sent to the automatic three-proof paint spraying equipment, and then a layer of polyurethane resin three-proof paint film layer is sprayed on the circuit board by the nozzle, and the thickness is controlled to be 500 μm.

[0075] Step 11: The circuit board sprayed with the polyurethane resin three-proof paint film layer is sent into an infrared curing oven for curing, or naturally air-dried, and the manufacturing is completed.

[0076] The structure of the power supply equipment circuit board for harsh environment is shown in Figure 7 .

[0077] The first layer of directly contacted film layer 1 deposited on the circuit board of the present application adopts SiO2 film, and the SiO2 film is prepared at a temperature below 80℃, which can avoid exposing the relatively fragile capacitor type components on the circuit board to high temperature environment during the preparation of the film, resulting in early performance decline. The film layer 2 adopts a low-temperature process to prepare an aluminum oxide (Al2O3) film on the SiO2 film to improve its thermal conductivity and hydrophilic properties, so that the SiO2 film can be protected, and the entire film system is more reliable. The top layer (i.e. Figure 7The middle film layer 3) is coated with a conventional polyurethane resin (UR) three-proofing paint film layer, which belongs to the current conventional circuit board three-proofing treatment technology, and the addition of this film layer can further protect the film layer 1 and the film layer 2 located in the inner layer, on the one hand, the direct contact of the film layer 1 and the film layer 2 with the environment can be further reduced, the environmental tolerance of the whole film layer is improved, and the circuit board and its components are better protected, on the other hand, since the film layer 1 and the film layer 2 are prepared by a vacuum coating process, the thin film prepared is thin (usually nm level) and is easy to be worn and penetrated in the installation and other work, and the film layer 3 is prepared by a coating or spraying process, the film layer prepared is thick (usually mm level), and the film layer 3 can effectively protect the film layer 1 and the film layer 2 from being worn in the production and transportation process. The use of the film layer 3 can further improve the reliability of the whole film layer.

[0078] Embodiment 2, a preparation method of a circuit board for a power supply device in a harsh environment

[0079] The preparation method of the circuit board for the power supply device in the harsh environment is that three film layers are sequentially plated on the surface of the circuit board to obtain the circuit board for the power supply device in the harsh environment, the film layer 1 is in direct contact with the circuit board, the film layer 1 is a silicon dioxide film layer, the thickness of the film layer 1 is 100 nm, the film layer 2 is an aluminum oxide film layer, the thickness of the film layer 2 is 100 nm, and the film layer 3 is a polyurethane resin three-proofing paint film layer located at the top layer, and the thickness of the film layer 3 is 1500 μm.

[0080] The flowchart of the preparation of the circuit board for the power supply device in the harsh environment by the linear array continuous multi-chamber magnetron sputtering equipment in the embodiment 2 of the application is shown in Figure 2 .

[0081] The structural diagram of the linear array continuous multi-chamber magnetron sputtering equipment is shown in Figure 3 , wherein:

[0082] (1) Each chamber is closed and isolated by airtight valves to ensure independence and no air leakage between each other;

[0083] (2) The 1# chamber is an atmospheric-vacuum isolation buffer chamber (equipment inlet buffer chamber), which continuously performs air charging and air pumping, and continuously switches between a low vacuum state (1-10 Pa) and a normal pressure state, so that the circuit board to be plated can enter the plating equipment from the outside;

[0084] (3) The 2# chamber is a buffer pretreatment chamber + gas vacuum flushing, which is usually in a high vacuum state (10 -3 Pa), and is used for entering the circuit board to be plated into a high vacuum state from a low vacuum chamber, and performing appropriate heating treatment (80℃) on the circuit board to improve the film layer film forming quality;

[0085] (4)2#-5# chamber have heating device, so that the plated circuit board can be kept at the required temperature (80℃) ;

[0086] (5)3# chamber is Ar gas glow discharge cleaning chamber, high-purity argon (Ar) is passed into the chamber, so that the pressure in the chamber is maintained within a certain range, generally 0.1-1Pa (this pressure range can ensure the stable formation of subsequent glow discharge) ;

[0087] (5)4# chamber is a coating chamber 1 (sputtering SiO2 film), equipped with SiO2 target, used for magnetron sputtering reaction, sputtering SiO2 film, this chamber is in a high vacuum state (10 -3 Pa) for a long time;

[0088] (6)5# chamber is a coating chamber 2 (sputtering Al2O3 film), equipped with Al2O3 target, used for magnetron sputtering reaction, sputtering Al2O3 film, this chamber is in a high vacuum state (10 -3 Pa) for a long time;

[0089] (7)6# chamber is a buffer chamber, which is usually in a high vacuum state (10 -3 Pa), used to buffer and isolate the coated circuit board from the high vacuum chamber to the low vacuum state, to ensure the high vacuum purity of 4#, 5# reaction chamber, so as to avoid pollution and cause the decline of film quality;

[0090] (8)7# chamber is an atmospheric-vacuum isolation buffer chamber (device outlet chamber), which constantly charges and pumps, constantly switches between low vacuum state (1-10Pa) and normal pressure state, so that the coated circuit board can be switched from high vacuum chamber to low vacuum state and enter normal pressure state, and sent out of the device;

[0091] The specific preparation steps of the power supply equipment circuit board for harsh environment are as follows:

[0092] Before starting production, the magnetron sputtering equipment has been pumped to a vacuum state by a vacuum pump, wherein 1# chamber, 3# chamber and 7# chamber are in a low vacuum state (1-10Pa), and 2# chamber, 4# chamber, 5# chamber and 6# chamber are in a high vacuum state (10 -3 Pa).

[0093] Step 1: Blow off the dust on the circuit board to be coated to ensure that there is less dust on the circuit board before entering the vacuum coating equipment.

[0094] Step 2: As above Figure 3At this time, the chamber vent valve of the magnetron sputtering device 1# is opened to introduce atmosphere into the chamber to reach the atmospheric pressure level. Since the 1# chamber and the outside are both at the atmospheric pressure at this time, the pressure is consistent. Then the A valve is opened, and the circuit board to be coated is sent into the 1# chamber through the conveying belt, and the A valve is closed.

[0095] Step 3: as above Figure 3 After the circuit board to be coated is sent into the 1# chamber, the 1# chamber is vacuumized to a low vacuum state (1-10 Pa). At this time, the pressure difference between the 1# and 2# chambers (high vacuum state) is very small. The B valve is opened, and the circuit board to be coated is sent into the 2# chamber through the conveying belt. The B valve is closed, and the 2# chamber is restored to the high vacuum state.

[0096] Step 4: The 2# chamber is a buffer pretreatment + gas vacuum flushing chamber (vacuum cleaning chamber box). The longitudinal section view of the 2# chamber vacuum cleaning chamber box is shown in Figure 4 The other longitudinal section view of the 2# chamber vacuum cleaning chamber box is shown in Figure 5 The 2# chamber includes a box body, an air inlet joint 4 is arranged outside the box body, a vacuum cavity wall 5 is arranged in the box body, an exhaust pipe 6 is arranged in the vacuum cavity wall, a plurality of air outlet holes 7 are uniformly arranged on the exhaust pipe 6, the middle section of the exhaust pipe 6 is connected with the air inlet joint 4 through a metal bellows pipe 8 with good expansion performance, an air inlet 9 in communication with the vacuum cavity wall 5 is arranged outside the box body, the vacuum cavity wall 5 and the air inlet 9 are connected through an air inlet pipe 10, an MFC mass flow meter 12 is arranged on the air inlet pipe 10, the air inlet 9 and the exhaust pipe 6 are connected through the bellows pipe 8, the air inlet pipe 10 and the bellows pipe 8 are connected through the air inlet joint 4, a motor 13 is arranged outside the box body, a cam link mechanism 14 is arranged inside the box body, a rotating shaft of the motor 13 adopts a magnetic fluid seal 16, the air inlet 9 and the exhaust pipe 6 of the vacuum chamber are connected through the bellows pipe 8, so that the exhaust pipe 6 can move up and down, the motor 13 is rotated to drive the cam link mechanism 14 to drive the exhaust pipe 6 to vertically reciprocate, two slide rods 15 are arranged on the exhaust pipe 6, the slide rods 15 are sleeved in pin sleeves 17 fixed on the inner wall of the vacuum box body, which ensures that the exhaust pipe 6 can move vertically on the plane where the two pin sleeves 17 are located when reciprocating up and down, and cannot swing randomly. A metal bellows pipe with good expansion performance is connected between the air inlet joint and the exhaust pipe in the cavity, which can meet the requirement of reciprocating up and down. The air inlet and the exhaust pipe of the vacuum chamber are connected through the bellows pipe, so that the exhaust pipe can move up and down by the motor. A heater is arranged in the 2# chamber, which can preheat the circuit board to be coated to gradually reach a temperature of 80℃, so as to facilitate high-quality sputtering film formation.

[0097] The circuit board is pretreated, including the steps of vacuumizing and pre-cleaning in the 2# chamber, dynamic jet cleaning, and cleaning in the 3# argon glow discharge cleaning chamber, wherein the specific steps of the 2# chamber treatment are as follows:

[0098] The 2# chamber is vacuumized to a high vacuum degree (1x10-3 Pa), the circuit board to be plated is pre-cleaned in the 2# chamber, low-pressure argon Ar (0.1-0.5 bar) is sprayed to remove loose contaminants, the pre-cleaning gas flow is 10 L / min, and the pre-cleaning time is 1 min; the circuit board is dynamically jet cleaned, specifically including 1) motor-driven exhaust pipe movement: movement parameters: stroke range 500 mm, exhaust pipe stroke speed 0.3 m / s, 2) gas jet control: gas pressure: 2.0 bar, spraying time: 10 minutes, 3) vacuum dynamic balance: the pressure is monitored in real time through a vacuum gauge, the inlet valve and the pump speed are adjusted, and the vacuum degree fluctuation is maintained to be ≤±5%; after the flushing is completed, the inlet valve is closed, and the chamber is vacuumized to a high vacuum state (to the order of 10-3 Pa) by a vacuum pump;

[0099] Step 5: as shown in Figure 3 , the C valve is opened, the circuit board to be plated is sent into the 3# argon glow discharge cleaning chamber, argon Ar is used for glow discharge plasma cleaning, and the cleaning time is controlled to be 10 min; through the high-energy argon ion impact on the contaminant molecules on the surface of the workpiece, the contaminant molecules are separated from the surface of the workpiece. For organic contaminants such as oil stains and photoresist, the argon ion bombardment can decompose them into small molecular fragments, and then the fragments are pumped away by a vacuum pump. For inorganic contaminants such as metal oxides and dust particles, the argon ion can knock them off the surface. The cleaning degree of the circuit board is further improved through the glow discharge plasma cleaning, and the quality of the subsequent plating is improved;

[0100] Step 6: the D valve is opened, the circuit board to be plated is sent into the 4# chamber through a conveying belt, and then the D valve is closed, the chamber is provided with a SiO2 target, at this time, inert gas (argon Ar) is introduced into the chamber, when the reaction pressure reaches 0.5-1 Pa, the power is applied to the target to excite the glow, the SiO2 target is sputtered, and the circuit board surface is plated, and the sputtering power density is controlled to be 10 W / cm 2 . Since the vacuum and stable reaction pressure need to be maintained, and the argon gas is consumed during the sputtering process, the argon gas needs to be continuously introduced during the reaction process, which is adjusted and controlled through a flowmeter. A film thickness meter can be added to measure the thickness of the SiO2 film generated on the circuit board, and when the film reaches a predetermined thickness (100 nm), the sputtering is stopped, the argon gas inflow is closed, and the chamber is vacuumized to a high vacuum state.

[0101] Step 7: When the sputtering of the SiO2 film in the 4# chamber is completed and the chamber is pumped to high vacuum, the E valve is opened, the circuit board to be coated is sent into the 5# chamber by the conveyor belt, and then the E valve is closed. The 5# chamber contains an Al2O3 target. At this time, inert gas (argon Ar) is introduced into the chamber. When the reaction pressure reaches 0.5-1 Pa, the power is turned on to excite the glow on the target, and the sputtering of the Al2O3 target and the film formation on the circuit board surface are started. The sputtering power density is controlled at 12 W / cm 2 . Due to the consumption of argon during the sputtering process and the need to maintain vacuum and stable reaction pressure, argon needs to be continuously introduced during the reaction process, which is adjusted and controlled by the flow meter. A film thickness meter can be added here to measure the thickness of the Al2O3 film formed on the circuit board. When the film reaches the predetermined thickness (100 nm), the sputtering is stopped and the argon flow is stopped. The chamber is pumped to high vacuum.

[0102] Step 8: After the Al2O3 film is formed in the 5# chamber and the chamber is pumped to high vacuum, the F valve is opened, and the coated circuit board is sent into the 6# buffer chamber by the conveyor belt. The F valve is closed.

[0103] Step 9: The G valve is opened, and the circuit board is sent into the 7# chamber (vacuum-atmosphere isolation buffer chamber) in low vacuum. The G valve is closed, and the chamber is filled with air to restore the pressure in the 7# chamber to atmospheric pressure. At this time, the 7# chamber and the external environment are at atmospheric pressure, and there is no pressure difference. The H valve is opened, and the coated circuit board is sent out by the conveyor belt, completing the process of sputtering SiO2 film and Al2O3 film by magnetron sputtering.

[0104] Step 10: The coated circuit board is taken out and sent to the automatic three-proof paint spraying equipment, and then a layer of polyurethane resin three-proof paint film is sprayed on the circuit board by the nozzle, with a thickness of 1500 μm.

[0105] Step 11: The circuit board with the sprayed polyurethane resin three-proof paint film is sent into the infrared curing oven for curing, or naturally air-dried, completing the production.

[0106] The structure of the power equipment circuit board for harsh environments is shown in Figure 7 .

[0107] Example 3, a method for preparing a power equipment circuit board for harsh environments

[0108] The preparation method of the power supply equipment circuit board for harsh environment comprises the following steps: sequentially plating three layers of films on the surface of the circuit board to obtain the power supply equipment circuit board for harsh environment, wherein the film layer 1 is in direct contact with the circuit board, the film layer 1 is a silicon dioxide film layer, and the thickness of the film layer 1 is 50 nm; the film layer 2 is an aluminum oxide film layer, and the thickness of the film layer 2 is 300 nm; and the film layer 3 is a polyurethane resin three-protection paint film layer at the top layer, and the thickness of the film layer 3 is 1000 μm.

[0109] The flowchart of the preparation of the power supply equipment circuit board for harsh environment by the linear array continuous multi-chamber magnetron sputtering equipment in the embodiment 3 is shown in Figure 2 .

[0110] The structural diagram of the linear array continuous multi-chamber magnetron sputtering equipment is shown in Figure 3 , wherein:

[0111] (1) The chambers are closed and isolated from each other by airtight valves to ensure independence and no air leakage between them;

[0112] (2) The 1# chamber is an atmospheric-vacuum isolation buffer chamber (equipment inlet buffer chamber), which continuously performs air charging and air exhausting, and switches between the low vacuum state (1-10 Pa) and the normal pressure state, so that the circuit board to be plated can enter the plating equipment from the outside;

[0113] (3) The 2# chamber is a buffer pretreatment chamber + gas vacuum flushing, which is usually in a high vacuum state (10 -3 Pa), and is used for entering the circuit board to be plated into the high vacuum state from the low vacuum chamber, and performing appropriate heating treatment (65℃) on the circuit board to improve the film layer film forming quality;

[0114] (4) The 2#-5# chambers are all provided with heating devices, so that the circuit board to be plated can be kept at the required temperature (65℃);

[0115] (5) The 3# chamber is an Ar gas glow discharge cleaning chamber, high-purity argon (Ar) is introduced into the chamber to maintain the pressure in the chamber within a certain range, generally 0.1-1 Pa (this pressure range can ensure the stable formation of the subsequent glow discharge);

[0116] (6) The 4# chamber is a film plating chamber 1 (sputtering SiO2 film), which is provided with a SiO2 target material, is used for magnetron sputtering reaction, and sputters SiO2 film, and the chamber is in a high vacuum state (10 -3 Pa) for a long time;

[0117] (7) The 5# chamber is a film plating chamber 2 (sputtering Al2O3 film), which is provided with an Al2O3 target material, is used for magnetron sputtering reaction, and sputters Al2O3 film, and the chamber is in a high vacuum state (10 -3 Pa) for a long time.

[0118] (8)6# chamber is a buffer chamber, which is usually in a high vacuum state (10 -3 Pa), for buffering and isolating the circuit board with plated film from the high vacuum chamber to the low vacuum state, to ensure the high vacuum purity of 4#, 5# reaction chamber, so as to avoid pollution and cause the film quality to decrease;

[0119] (9)7# chamber is an atmospheric-vacuum isolation buffer chamber (device outlet chamber), which is constantly filled with air and pumped, and constantly switches between the low vacuum state (1-10 Pa) and the normal pressure state, so that the circuit board with plated film can be switched from the high vacuum chamber to the low vacuum state and enter the normal pressure state, and be sent out of the device;

[0120] The specific preparation steps of the power supply device circuit board for harsh environments are as follows:

[0121] Before starting the production, the magnetron sputtering device has been pumped to a vacuum state by a vacuum pump, wherein the 1# chamber, the 3# chamber, and the 7# chamber are in a low vacuum state (1-10 Pa), and the 2# chamber, the 4# chamber, the 5# chamber, and the 6# chamber are in a high vacuum state (10 -3 Pa).

[0122] Step 1: The circuit board to be plated is subjected to a simple treatment of blowing and dust removal, to ensure that there are less dust and debris on the circuit board before entering the vacuum plating device.

[0123] Step 2: As shown in the above Figure 3 , the 1# chamber of the magnetron sputtering device is opened to the atmosphere to make the chamber reach the atmospheric pressure level, because the pressure of the 1# chamber and the outside is consistent at this time, then the A valve is opened, the circuit board to be plated is sent into the 1# chamber through the conveyor belt, and the A valve is closed.

[0124] Step 3: As shown in the above Figure 3 , after the circuit board to be plated is sent into the 1# chamber, the 1# chamber is pumped to a low vacuum state (1-10 Pa), at this time, the pressure difference between the 1# chamber and the 2# chamber (high vacuum state) is very small, the B valve is opened, the circuit board to be plated is sent into the 2# chamber through the conveyor belt, and the B valve is closed, so that the 2# chamber returns to a high vacuum state.

[0125] Step 4: The 2# chamber is a buffer pretreatment + gas vacuum flushing chamber (vacuum cleaning chamber box), the longitudinal sectional view of the 2# chamber vacuum cleaning chamber box is shown in the above Figure 4 , and another longitudinal sectional view of the 2# chamber vacuum cleaning chamber box is shown in the above Figure 5The 2# chamber includes a box, which is externally provided with a cavity inlet hole connector 4, and internally provided with a vacuum cavity wall 5, and the vacuum cavity wall is internally provided with an exhaust pipe 6, which is externally provided with uniformly distributed exhaust holes 7, and the middle section of the exhaust pipe 6 is connected with the cavity inlet hole connector 4 through a metal bellows 8 with good stretchability, and the box is externally provided with an air inlet 9 in communication with the vacuum cavity wall 5, and the vacuum cavity wall 5 and the air inlet 9 are connected through an air inlet pipe 10, and the air inlet pipe 10 is externally provided with an MFC mass flow meter 12, and the air inlet 9 and the exhaust pipe 6 are connected through the bellows 8, and the air inlet pipe 10 and the bellows 8 are connected through the cavity inlet hole connector 4, and the box is externally provided with a motor 13, and the box is internally provided with a cam connecting rod mechanism 14, and the rotating shaft of the motor 13 adopts a magnetic fluid seal 16, and the air inlet 9 and the exhaust pipe 6 of the vacuum chamber are connected through the bellows 8, so that the exhaust pipe 6 can move up and down, and the motor 13 is rotated to drive the cam connecting rod mechanism 14 to drive the exhaust pipe 6 to vertically reciprocate, and the exhaust pipe 6 is externally provided with two slide rods 15, and the slide rods 15 are sleeved in pin sleeves 17 fixed on the inner wall of the vacuum box, which ensures that the exhaust pipe 6 can vertically move on the plane where the two pin sleeves 17 are located when reciprocating up and down, and will not swing randomly. A section of metal bellows with good stretchability is connected between the cavity inlet hole connector and the exhaust pipe in the cavity, which can meet the requirements of reciprocating motion up and down, and the air inlet and the exhaust pipe of the vacuum chamber are connected through the bellows, so that the exhaust pipe can move up and down, and the exhaust pipe moves up and down through the motor. A heater is arranged in the 2# chamber, which can preheat the entering circuit board to be plated to gradually reach a temperature of 65℃, so as to facilitate high-quality sputtering film formation.

[0126] The circuit board is pretreated, including the steps of vacuumizing and pre-cleaning in the 2# chamber, dynamic air jet flushing cleaning, and cleaning in the 3# argon glow discharge cleaning chamber, and the specific steps of the treatment in the 2# chamber are as follows:

[0127] The 2# chamber is vacuumized to a high vacuum degree (1x10-3Pa), the circuit board to be plated is pre-cleaned in the 2# chamber, low-pressure argon Ar (0.1-0.5 bar) is sprayed to remove loose contaminants, the pre-cleaning gas flow is 7L / min, and the pre-cleaning time is 30s; the circuit board is dynamically air jet flushed and cleaned, specifically including 1) motor-driven exhaust pipe movement: movement parameters: stroke range 300mm, exhaust pipe stroke speed 0.2m / s, 2) gas injection control: gas pressure: 1bar, spraying time: 5 minutes, 3) vacuum dynamic balance: the pressure is monitored in real time through a vacuum gauge, the air inlet valve and the pump speed are adjusted, and the vacuum degree fluctuation is maintained to be less than or equal to ±5%;

[0128] After the flushing is completed, the air inlet valve is closed, and the vacuum pump is used to vacuum the chamber to a high vacuum state (to reach the order of 10-3Pa);

[0129] Step 5: As shown in Figure 3 Step 5: As shown in

[0130] Step 6: Open the D valve, and send the circuit board to be plated into the 4# chamber through the conveyor belt, then close the D valve. The 4# chamber is filled with SiO2 target material. At this time, inert gas (argon Ar) is introduced into the chamber. When the reaction pressure reaches 0.5-1 Pa, the power is turned on to excite the glow on the target, and the sputtering of the SiO2 target and the film formation on the surface of the circuit board begin. The sputtering power density is controlled at 6 W / cm 2 . Due to the need to maintain vacuum and stable reaction pressure, as well as the consumption of the sputtering process itself, the argon gas is constantly reduced, and needs to be continuously introduced during the reaction process. This is adjusted and controlled by the flow meter. A film thickness meter can be added here to measure the thickness of the SiO2 film generated on the circuit board. When the film reaches the predetermined thickness (50 nm), the sputtering is turned off, the argon gas inflow is closed, and the high vacuum state is restored.

[0131] Step 7: After the SiO2 film sputtering in the 4# chamber is completed and the gas is pumped to restore the high vacuum state, the E valve is opened, and the circuit board to be plated is sent into the 5# chamber through the conveyor belt. Then the E valve is closed. The 5# chamber is filled with Al2O3 target material. At this time, inert gas (argon Ar) is introduced into the chamber. When the reaction pressure reaches 0.5-1 Pa, the power is turned on to excite the glow on the target, and the sputtering of the Al2O3 target and the film formation on the surface of the circuit board begin. The sputtering power density is controlled at 10 W / cm 2 . Due to the need to maintain vacuum and stable reaction pressure, as well as the consumption of the sputtering process itself, the argon gas is constantly reduced, and needs to be continuously introduced during the reaction process. This is adjusted and controlled by the flow meter. A film thickness meter can be added here to measure the thickness of the Al2O3 film generated on the circuit board. When the film reaches the predetermined thickness (300 nm), the sputtering is turned off, the argon gas inflow is closed, and the high vacuum state is restored.

[0132] Step 8: After the Al2O3 film is made in the 5# chamber and the high vacuum state is restored, the F valve is opened, and the plated circuit board is sent into the high vacuum 6# buffer chamber through the conveyor belt. The F valve is closed.

[0133] Step 9: open G valve, send the circuit board into the low vacuum 7# chamber (vacuum-atmosphere isolation buffer chamber). Close G valve, fill the chamber with atmosphere, so that the pressure in 7# chamber returns to atmospheric pressure level. At this time, 7# chamber and the external environment are both at atmospheric pressure, there is no pressure difference, open H valve, send the coated circuit board out through the conveyor belt, complete the process of magnetron sputtering and sputtering SiO2 film and Al2O3 film.

[0134] Step 10: take out the coated circuit board and send it to the automatic three-proof paint spraying equipment, then spray a layer of polyurethane resin three-proof paint film on the circuit board by the nozzle, the thickness is controlled to be 1000 μm.

[0135] Step 11: send the circuit board sprayed with polyurethane resin three-proof paint film into the infrared curing oven for curing, or air dry naturally, complete the production.

[0136] The structure of the power supply equipment circuit board for harsh environment is shown in Figure 7

[0137] Comparative Example 1, the circuit board of this comparative example has no protective film layer.

[0138] Comparative Example 2, the preparation method of the power supply equipment circuit board

[0139] The preparation method of the power supply equipment circuit board is to only use the conventional polyurethane resin (UR) three-proof paint film layer spraying protection on the surface of the circuit board, and the thickness is the same as that of the polyurethane resin three-proof paint film layer in Example 3.

[0140] Comparative Example 3, the preparation method of the power supply equipment circuit board

[0141] The preparation method of the power supply equipment circuit board is to coat 3 layers of film on the surface of the circuit board in sequence to obtain the power supply equipment circuit board for harsh environment, film layer 1 is in direct contact with the circuit board, film layer 1 is a silicon dioxide film layer, the thickness of film layer 1 is 50 nm; film layer 2 is an aluminum oxide film layer, the thickness of film layer 2 is 300 nm; film layer 3 is a polyurethane resin three-proof paint film layer on the top layer, the thickness of film layer 3 is 1000 μm.

[0142] The preparation method of the power supply equipment circuit board of this comparative example is similar to that of Example 3.

[0143] The difference from Example 3 is that the preparation method of the power supply equipment circuit board does not include the step of dynamically spraying and rinsing the circuit board.

[0144] Test Example 1, performance test

[0145] ​1. Test materials: the power supply equipment circuit board prepared in Example 3, the circuit board without protective film layer in Comparative Example 1, and the power supply equipment circuit board prepared by spraying a protective film layer of conventional polyurethane resin (UR) three-proofing paint in Comparative Example 2.

[0146] 2. Test method:

[0147] Before the experiment, the insulation resistance of the power supply equipment circuit board prepared in Example 3, the circuit board without protective film layer in Comparative Example 1, and the power supply equipment circuit board prepared by spraying a protective film layer of conventional polyurethane resin (UR) three-proofing paint in Comparative Example 2 was detected by referring to the method 302 insulation resistance test in GJB 360A-96 "Electronic and Electrical Component Test Methods". An insulation resistance tester was used, 500V direct current voltage was applied, and the measurement value was read after 1 min of power-on. The dielectric withstand voltage of the power supply equipment circuit board prepared in Example 3, the circuit board without protective film layer in Comparative Example 1, and the power supply equipment circuit board prepared by spraying a protective film layer of conventional polyurethane resin (UR) three-proofing paint in Comparative Example 2 was tested by referring to the method 301 dielectric withstand voltage test in GJB 360A-96 "Electronic and Electrical Component Test Methods".

[0148] The power supply equipment circuit board prepared in Example 3, the circuit board without protective film layer in Comparative Example 1, and the power supply equipment circuit board prepared by spraying a protective film layer of conventional polyurethane resin (UR) three-proofing paint in Comparative Example 2 were subjected to a salt spray test by referring to GJB 150.11A-2009 "Military Equipment Laboratory Environmental Test Methods Part 11: Salt Spray Test". The test temperature was (35±2)℃, the mass fraction of the salt solution was 5%±1% (NaCl), the pH value of the salt solution was 6.5-7.2, the salt spray deposition rate was (1.0-2.0)mL / (80cm 2 h), and the spraying mode was continuous. After the salt spray test for 240h, a damp heat test was performed. The damp heat test was performed by referring to the humidity resistance test in GJB 360A-96 "Electronic and Electrical Component Test Methods", a total of 10 cycles were performed, and a 100V direct current polarization voltage was applied during the test. One cycle was 24h, which was divided into three stages of temperature rise, high temperature maintenance, and temperature drop, and high humidity conditions were maintained during the period. After the damp heat test for 240h, the appearance of the material after the experiment was observed, and the insulation resistance and dielectric withstand voltage of the material after the experiment were detected. The dielectric withstand voltage of the samples of Example 3, Comparative Example 1, and Comparative Example 2 was tested by referring to the method 301 dielectric withstand voltage test in GJB 360A-96 "Electronic and Electrical Component Test Methods".

[0149] 3. The test results are shown in Table 1.

[0150] Table 1: Performance test results

[0151]

[0152]

[0153] As can be seen from Table 1, the appearance of the power supply equipment circuit board prepared by the embodiment 3 of the present application after the experiment shows slight corrosion, a small amount of rust in the plated hole, and slight spot corrosion on the coating layer, while the appearance of the circuit board without the protective film layer of the comparative example 1 after the experiment shows serious corrosion, corrosion in the plated hole, and spot corrosion and pinholes in the coating layer; the appearance of the power supply equipment circuit board prepared by the comparative example 2 after the experiment shows spot corrosion, corrosion in the plated hole, and spot corrosion on the coating layer; the change in the insulation resistance of the power supply equipment circuit board prepared by the embodiment 3 of the present application before and after the experiment is obviously smaller than that of the comparative examples 1 and 2; the dielectric withstand voltage of the power supply equipment circuit board prepared by the embodiment 3 of the present application after the experiment is normal, while the dielectric withstand voltage of the circuit board without the protective film layer of the comparative example 1 after the experiment is breakdown, and the dielectric withstand voltage of the power supply equipment circuit board prepared by the comparative example 2 after the experiment shows spark. It can be seen that, compared with the comparative examples 1 and 2, the power supply equipment circuit board prepared by the embodiment 3 of the present application has excellent moisture and heat resistance and salt spray resistance, and can better cope with the use in the marine and other harsh environments.

[0154] Test example two, long-term salt spray test

[0155] 1. Test materials: the power supply equipment circuit board for harsh environments prepared by the embodiment 3, and the power supply equipment circuit board prepared by the comparative example 2 using the conventional polyurethane resin (UR) three-protection paint film layer for spraying protection.

[0156] 2. Test method:

[0157] Six circuit boards of the same batch were taken, and the circuit boards were all qualified and normally functional after power-on. Three circuit boards were prepared into power supply equipment circuit boards for harsh environments according to the method of the embodiment 3, and three circuit boards were prepared into power supply equipment circuit boards according to the method of the comparative example 2. The six circuit boards after the protection treatment were all put into a salt spray test box for long-term salt spray test. The test method referred to GJB150.11A-2009 Military Equipment Laboratory Environmental Test Method Part 11: Salt Spray Test, the test temperature was (35±2) ℃, the mass fraction of the salt solution was 5%±1% (NaCl), the pH value of the salt solution was 6.5-7.2, the salt spray deposition rate was (1.0-2.0) mL / (80 cm 2 ·h), and the spraying mode was continuous. The circuit boards were taken out every other day after 4 days of test, and the functions were tested to see if they were normally running. The average failure time was recorded.

[0158] 3. The test results are shown in Table 2.

[0159] Table 2 Long-term salt spray test results

[0160]

[0161] As shown in Table 2, compared with the power supply equipment circuit board prepared in Comparative Example 2, the power supply equipment circuit board prepared in Example 3 of the application has more excellent long-term salt spray resistance.

[0162] Test Example Three,

[0163] 1. Test materials: the power supply equipment circuit board for harsh environment prepared by using the dynamic air jet rinsing process in Example 3, and the power supply equipment circuit board prepared without using the dynamic air jet rinsing process in Comparative Example 3.

[0164] 2. Test method:

[0165] Six circuit boards of the same batch were taken, and the circuit boards were all qualified and had normal functions after power-on. Three circuit boards were made into the power supply equipment circuit board for harsh environment according to the method of Example 3, and the other three circuit boards were made into the power supply equipment circuit board according to the method of Comparative Example 3. The six circuit boards after protection treatment were all put into a salt spray test box for long-term salt spray test. The test method referred to GJB150.11A-2009 Military Equipment Laboratory Environmental Test Method Part 11: Salt Spray Test, the test temperature was (35±2)℃, the mass fraction of the salt solution was 5%±1% (NaCl), the pH value of the salt solution was 6.5-7.2, the salt spray deposition rate was (1.0-2.0) mL / (80 cm 2 ·h), and the spraying mode was continuous. After 4 days of test, the circuit boards were taken out every other day, and the functions were tested to see if they ran normally. The average failure time was recorded.

[0166] 3. The test results are shown in Table 3.

[0167] Table 3 Long-term salt spray test results

[0168]

[0169] As shown in Table 3, compared with the power supply equipment circuit board prepared without using the dynamic air jet rinsing process in Comparative Example 3, the power supply equipment circuit board prepared by using the dynamic air jet rinsing process in Example 3 of the application has more excellent long-term salt spray resistance. In the pretreatment process of the circuit board, the dynamic air jet rinsing process is used to improve the cleanliness of the circuit board before vacuum coating, to ensure the film forming quality of the vacuum coating of the circuit board, and to further improve the long-term salt spray resistance of the product.

Claims

1. A method of manufacturing a circuit board for a power supply device for a severe environment, characterized by, The power supply equipment circuit board for harsh environment is obtained by sequentially plating N layers of films on the surface of the circuit board, N is a positive integer greater than or equal to 2, the first layer of film is in direct contact with the circuit board, and the first layer of film is one of a silicon dioxide film layer, an aluminum oxide film layer, a silicon nitride film layer, a titanium dioxide film layer, and an aluminum nitride film layer; The preparation method of the power supply equipment circuit board for harsh environment comprises the following steps: S1: feeding the circuit board into an atmosphere-vacuum isolation buffer chamber, vacuumizing, and then feeding the circuit board into a buffer pretreatment+gas vacuum flushing chamber; S2: vacuumizing the buffer pretreatment+gas vacuum flushing chamber, and pre-cleaning and dynamic air jet flushing cleaning the circuit board with gas, and vacuumizing after the cleaning; S3: feeding the cleaned circuit board into a glow discharge cleaning chamber, and cleaning the circuit board with working gas; S4: feeding the treated circuit board into a film plating chamber provided with a target material, and plating films by vacuum plating process, and sputtering the first to N-1 layers of films; S5: feeding the circuit board with plated films obtained in step S4 into a buffer chamber and a vacuum-atmosphere isolation buffer chamber in sequence, and then spraying the Nth layer of film after feeding out the circuit board; The specific operation of the pre-cleaning in step S2 is: the gas with a pressure of 0.1-0.5 bar is introduced, the gas flow rate during pre-cleaning is 5-10 L / min, and the pre-cleaning time is 10 s-1 min; during the dynamic air jet flushing cleaning in step S2, the exhaust pipe is driven to move by a motor, the travel speed of the exhaust pipe is 0.1-0.3 m / s; the gas jet is controlled, the gas pressure is 0.5-2.0 bar, and the spraying time is 2-10 minutes.

2. The method of manufacturing a circuit board for a power supply apparatus for harsh environments according to claim 1, characterized by, When N>2, the second layer of film to the N-1 layer of film are one of an aluminum oxide film layer, a silicon nitride film layer, a titanium dioxide film layer, and an aluminum nitride film layer; and the Nth layer of film is one of an acrylic resin three-protection paint film layer, a modified epoxy resin three-protection paint film layer, a silicone resin three-protection paint film layer, a polyurethane resin three-protection paint film layer, and a poly-p-xylylene three-protection paint film layer.

3. The method of manufacturing a circuit board for a power supply apparatus for harsh environments according to claim 1, characterized by, The thickness of the first layer of film is 20-100 nm, and the thickness of the Nth layer of film is 500-1500 m; when N>2, the thickness of the second layer of film to the N-1 layer of film is 100-500 nm.

4. The method of manufacturing a circuit board for a power supply device for harsh environments according to claim 1, characterized by, The step S1 is vacuumized to 1~10Pa; the step S2 is vacuumized to 1×10 -3 Pa~5×10 -3 Pa; the gas of the step S2 is argon or nitrogen; the working gas of the step S3 is argon or nitrogen.

5. The method of manufacturing a circuit board for a power supply apparatus for harsh environments according to claim 1, characterized in that, The vacuum plating process in step S4 is a magnetron sputtering method.

6. The method of manufacturing a circuit board for a power supply apparatus for harsh environments according to claim 5, characterized in that, The magnetron sputtering reaction pressure is 0.5-1 Pa.

7. The method of manufacturing a circuit board for a power supply apparatus for harsh environments according to claim 1, characterized by, The temperature of the buffer pretreatment+gas vacuum flushing chamber, the glow discharge cleaning chamber, and the film plating chamber is 50-80℃; in step S5: The buffer chamber is a high vacuum environment, and the pressure of the high vacuum is 1 x 10 -3 Pa~5 x 10 -3 Pa; During the process of feeding the circuit board with plated films obtained in step S4 into the vacuum-atmosphere isolation buffer chamber, the vacuum-atmosphere isolation buffer chamber is in a low vacuum environment, the pressure of the low vacuum is 1-10 Pa, after feeding in, the valve of the vacuum-atmosphere isolation buffer chamber is closed, and the atmosphere is filled in to restore the pressure in the vacuum-atmosphere isolation buffer chamber to the atmospheric pressure level.

8. The power supply equipment circuit board for harsh environment prepared by the preparation method of the power supply equipment circuit board for harsh environment according to any one of claims 1-7.

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