A waterproof PCB circuit board

Abstract

The present invention discloses a waterproof PCB circuit board, belonging to the technical field of PCB circuit boards. It includes a PCB board body, on which components are arranged and welded; the components include large-size components with a height exceeding 6 mm above the top surface of the PCB board body after welding and small-size components with a height not exceeding 6 mm above the top surface of the PCB board body after welding; it further includes a sealing seat, potting colloid and a waterproof coating, the sealing seat is fixed around the large-size components; the large-size components are embedded inside the sealing seat and pressed against the retaining edge, and the large-size components are welded to the PCB board body; the PCB board body is provided with a glue injection through hole inside the sealing seat; the potting colloid is poured into the sealed cavity formed by the large-size components, the sealing seat, the retaining edge and the PCB board body through the glue injection through hole; for the waterproof PCB circuit board of the present invention, the PCB board body itself has a waterproof effect, and at the same time, an external waterproof unit is used to encapsulate the PCB board body, which can prevent external water vapor from approaching the PCB board body and ensure the waterproof effect of the PCB board body.

Description

Technical Field

[0001] The present invention specifically relates to a waterproof PCB circuit board, belonging to the technical field of PCB circuit boards. Background Art

[0002] In the prior art, the waterproof technologies for circuit boards mainly include structural waterproofing, potting waterproofing, and waterproof and moisture-proof coatings. Among them, the waterproof and moisture-proof coating is the optimal solution for the current circuit board waterproof technology and can almost meet the waterproof requirements in any situation. However, the cost of large-area coating is too high. Potting waterproofing uses epoxy potting glue for potting electronic product modules, which has the problems of too large potting volume and difficult maintenance. Therefore, at present, the most common circuit board waterproof method is structural waterproofing. However, in actual applications, permeating water mist will be formed in the waterproof structure, which is likely to erode the circuit board. For this reason, Chinese Patent Publication No.: CN117163475A discloses a CBP waterproof circuit board. Under normal circumstances, since the air can flow in the waterproof box body, water vapor and water mist are not easily generated, and it is not easy to erode the CBP circuit board. However, this structure only seals the holding plate and the CBP circuit board through buoyancy, and the sealing effect is average. In addition, according to the circuit function requirements of the existing PCB circuit boards, various sizes of components need to be arranged, such as surface-mounted components and plug-in components. For plug-in components such as radiators, transformers, inductors, and rectifier tubes, the sizes are relatively large. If the waterproof coating is directly applied to the plug-in components, the consumption of the waterproof coating is large, and due to the obstruction of the components, the pins cannot be completely coated, so the waterproof effect cannot be achieved. In addition, for some sensors that need to be sensitive, such as photosensitive sensors, thermosensitive sensors, and humidity sensors, the detection surfaces of the sensors need to be protected. If the waterproof coating is directly applied to the detection surface, it is easy to affect the sensitivity of the sensors. Summary of the Invention

[0003] To solve the above problems, the present invention proposes a waterproof PCB circuit board. The PCB board itself has a waterproof effect. At the same time, an external waterproof unit is used to encapsulate the PCB board, which can prevent external water vapor from approaching the PCB board and ensure the waterproof effect of the PCB board.

[0004] The waterproof PCB circuit board of the present invention includes a PCB board body, and components are disposed and soldered on the PCB board body; the components include large-size components with a height exceeding 6 mm above the top surface of the PCB board after soldering and small-size components with a height not exceeding 6 mm above the top surface of the PCB board after soldering; it further includes:

[0005] Sealing base, the sealing base is fixed to the periphery of large-sized components; the inner side of the sealing base is a cavity with both ends hollow, a retaining edge is integrally formed on the inner side of the sealing base, the large-sized component is embedded in the inner side of the sealing base and pressed against the retaining edge, and the large-sized component is soldered to the PCB board body; the PCB board body is provided with glue injection through holes on the inner side of the sealing base;

[0006] Potting colloid, the potting colloid is poured into the sealed cavity formed by the large-sized component, the sealing base, the retaining edge and the PCB board body through the glue injection through holes; the potting colloid covers the bottom surface of the large-sized component;

[0007] Waterproof coating, the waterproof coating includes a first waterproof coating and a second waterproof coating; after the small-sized component is soldered to the PCB board body, the first waterproof coating is applied to the top surface of the PCB board body and the outside of the small-sized component; after all the components are soldered, the second waterproof coating is applied to the bottom surface of the PCB board body.

[0008] When processing a PCB waterproof circuit board, first perform PCB wiring according to the circuit schematic diagram, then, process the PCB board body, punch holes in the PCB board body, and apply a vacuum impregnated varnish coating. Then, solder the small-sized components to the PCB board body. After the soldering is completed, apply the first waterproof coating to the top surface of the PCB board body and the outside of the small-sized component to provide waterproof protection for the PCB board body and the small-sized component through the first waterproof coating. Then install the sealing base, fix the sealing base to the periphery of the installation position of the large-sized component. After the sealing base and the top surface of the PCB board body are installed, then, solder the large-sized component to the PCB board body and perform circuit testing; after the test passes, perform the potting colloid operation, align the glue injection head of the potting equipment with the glue injection through hole, and then inject the potting colloid into the sealed cavity formed by the large-sized component, the sealing base, the retaining edge and the PCB board body. The potting colloid fills and covers the large-sized component to provide waterproof protection for the lower part of the device body and the pins of the large-sized component, so that the PCB waterproof circuit board has a waterproof effect.

[0009] Further, the waterproof coating is a nano waterproof coating; the two sides of the PCB board body are provided with a vacuum impregnated varnish coating; the vacuum impregnated varnish coating can apply glue to both sides of the PCB board body; protect the circuit traces on the PCB board body.

[0010] Further, the sealing base is fixed to the PCB board body by adhesion or soldering; when soldering, it is necessary to pre-reserve the pin mounting holes for the sealing base when wiring the PCB board body in advance, and finally, solder the sealing base directly to the PCB board body as a component; when using the adhesion method, directly apply adhesive to the bottom of the sealing base, and finally, bond the sealing base to the PCB board body.

[0011] Further, when the pins of the large-sized component are located outside the component body, the retaining edge is a horizontal bar, and the potting colloid is poured in from the inner top of the sealing base and covers the pins of the large-sized component; the bottom of the large-sized component is limited by the retaining edge, so that the pins of the large-sized component can be kept at a set height, enabling the potting colloid to smoothly enter and fill the inside of the sealing base.

[0012] Further, the PCB board body is installed on an external waterproof unit, and the external waterproof unit includes an upper shell and a lower shell. A plurality of ear seats are integrally formed on one side of the outer parts of the upper shell and the lower shell close to each other; the ear seats are fastened by bolts and nuts, and a sealing ring is arranged between the upper shell and the lower shell; an inner ring seat is integrally formed on the inner side of the upper shell; a ring groove is formed in the inner ring seat, a plurality of blind holes are formed in the inner edge of the top surface of the PCB board body, and a pressing ring is adhesively fixed to the inner edge of the top surface of the PCB board body; an inserting column that fits into the blind holes is arranged on the pressing ring; the pressing ring is inserted into the inner side of the ring groove; an epoxy resin sealing layer is arranged between the outside of the PCB board body and the inside of the upper shell; a cable waterproof assembly is arranged at the end of the upper shell; the cable passes through the inside of the cable waterproof assembly, and the cable is electrically connected to the PCB board body; during installation, first, adhesive is applied to the pressing ring and the inner edge of the top surface of the PCB board body, and then, the cable on the PCB board body is led out from the cable waterproof assembly; then, the inserting column of the pressing ring is aligned and inserted into the blind holes of the PCB board body, so that a sealing surface is formed on the joint surface of the PCB board body and the pressing ring; then, the pressing ring is aligned and inserted into the ring groove of the inner ring seat, and finally, an epoxy resin sealing layer is obtained by coating and curing between the outside of the PCB board body and the inside of the upper shell; thus, a sealed cavity is formed between the inner side of the upper shell and the PCB board body; finally, the upper shell and the lower shell are aligned, the sealing ring is inserted, and finally, the ear seats on the upper shell and the lower shell are fastened together by bolts and nuts.

[0013] Further, the cable waterproof assembly includes a waterproof joint integrally fixed to the end of the upper shell; a screw sleeve is integrally formed on the upper shell outside the waterproof joint, a sealing head is screwed onto the screw sleeve, and the cable passes through the sealing head movably; potting colloid is arranged in the space formed by the screw sleeve and the sealing head; during operation, first, the connection of the PCB board body, the cable and the waterproof joint is completed, then, the cable is passed through the sealing head, and potting colloid is injected into the screw sleeve through the glue injection hole on the screw sleeve; thus, waterproof potting can be carried out on the connection between the waterproof joint and the cable.

[0014] Furthermore, a moisture-absorbing fiber felt is adhesively bonded to the inner surface of the upper housing; an outwardly convex chamber is integrally formed on the outer top surface of the upper housing; an exhaust pipe is fitted and fixed to the inner surface of the moisture-absorbing fiber felt within the upper housing; the exhaust pipe is connected to the outside of the outwardly convex chamber, and two mutually connected exhaust valves are provided on the exhaust pipe, and the exhaust valves are connected to the PCB board; a pressure transmitter and a humidity transmitter are provided on the PCB board; an inflation assembly is provided on the upper housing; when the humidity transmitter monitors that the water vapor inside the external waterproof unit reaches the set value, first open the external exhaust valve to make the pipe section from the outside of the exhaust pipe to the output end of the closed exhaust valve in the atmospheric pressure state, then close the external exhaust valve and open the internal exhaust valve. Since the pressure inside the external waterproof unit is greater than the atmospheric pressure, therefore, the moisture inside the external waterproof unit can be discharged into the exhaust pipe through the moisture-absorbing fiber felt. After the exhaust is completed, close the exhaust valve; the moisture-absorbing fiber felt continuously absorbs moisture. During exhaust, the moisture on the moisture-absorbing fiber felt can be carried away by the air flow, so as to maintain the moisture-absorbing property of the moisture-absorbing fiber felt; when the pressure transmitter detects that the pressure is lower than the set value, the PCB board sends a signal indicating that inflation is required, and the inflation assembly inflates the inside of the external waterproof unit, using the pressure difference between the inside and the outside of the external waterproof unit, so as to prevent water vapor from entering the inside of the external waterproof unit.

[0015] Furthermore, the inflation assembly is an inflation nozzle; during operation, compressed air is filled into the external waterproof unit through the inflation nozzle; so that the air pressure inside the external waterproof unit reaches the set pressure.

[0016] Furthermore, the inflation assembly includes a pump group fixed to the inner side of the upper housing, and the input end of the pump group is connected to the output end of the exhaust pipe; two check valves are connected in parallel to the output end of the exhaust pipe, and the opening directions of the check valves are opposite; the output end of the pump group is in a hollow state; the pump group is connected to the PCB board; when it is necessary to fill the inside of the external waterproof unit with compressed air, turn on the pump group to fill the air outside the external waterproof unit into the exhaust pipe through one check valve, and then fill it into the inside of the external waterproof unit through the pump group; when the inside of the external waterproof unit reaches the set pressure value, stop the pump group from working; when the pump group inflates the external waterproof unit, the outlet of the pump group faces the humidity transmitter. When the pump group is turned on, the humidity transmitter samples the humidity in real time. When the humidity exceeds the set value, stop inflating and delay inflating again until a suitable inflation environment is monitored for inflation. When multiple humidity samplings do not pass, a manual trigger inflation instruction is issued.

[0017] Compared with the prior art, for the PCB waterproof circuit board of the present invention, the PCB board body itself is coated with a load vacuum impregnation paint coating, which can protect the wiring of the PCB board body. Then, a nano waterproof coating is used to waterproof the two sides of the PCB board body, the outer surfaces of surface-mounted components and small-sized components, which can not only save the nano waterproof coating, but also avoid coating dead corners of the nano waterproof coating caused by the shielding of large-sized components; ensure the waterproof effect. Finally, a sealing seat is added to the outside of the large-sized components, and potting colloid is poured in to waterproof the periphery of the pins of the large-sized components and the lower part of the device body of the large-sized components; enable the devices on the PCB waterproof circuit board to have the effect of preventing water mist erosion; at the same time, enable the PCB board body itself to have a waterproof effect. At the same time, an external waterproof unit is used to encapsulate the PCB board body, which can isolate flowing water from approaching the PCB board body; when water vapor is generated inside the external waterproof unit, the water vapor can be discharged in time; thus, the PCB board body is always kept in a dry state. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the first waterproof coating applied after soldering small-sized components on the PCB board body of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the installation of the PCB board body, small-sized components and the sealing seat of the present invention.

[0020] Figure 3 It is a schematic structural diagram of the second waterproof coating applied on the PCB board body of the present invention.

[0021] Figure 4 It is a schematic structural diagram of the installation of the PCB board body, large-sized components with external pins and potting colloid of the present invention.

[0022] Figure 5 It is a schematic structural diagram of the installation of the PCB board body, large-sized components with internal pins and potting colloid of the present invention.

[0023] Figure 6 It is a schematic structural diagram of the installation of the PCB board body, voltage regulator diode and potting colloid of the present invention.

[0024] Figure 7 It is a schematic structural diagram of the installation of the PCB board body, sensor and potting colloid of the present invention.

[0025] Figure 8 It is a schematic structural diagram before the installation of the external waterproof unit and the PCB board body of the present invention.

[0026] Figure 9 It is a schematic structural diagram after the installation of the external waterproof unit and the PCB board body of the present invention.

[0027] Figure 10Schematic diagram of the structure before installation of the external waterproof unit, inflatable component and PCB board body of the present invention.

[0028] Figure 11 Of the present invention Figure 10 Schematic diagram of the partial enlarged structure at location A in

[0029] Figure 12 Schematic diagram of the structure before installation of the external waterproof unit, moisture-absorbing fiber felt and PCB board body of the present invention.

[0030] Figure 13 Schematic diagram of the external waterproof unit with the top surface facing down of the present invention.

[0031] Figure 14 Schematic diagram of the external waterproof unit with the top surface facing up of the present invention.

[0032] Reference numerals: 1, PCB board body; 2, large-sized components; 3, small-sized components; 4, sealing seat; 5, retaining edge; 6, glue injection through hole; 7, potting colloid; 8, first waterproof coating; 9, second waterproof coating; 10, upper housing; 11, lower housing; 12, ear seat; 13, inner ring seat; 14, annular groove; 15, compression ring; 16, embedding post; 17, cable; 18, waterproof joint; 19, screw sleeve; 20, end cap; 21, moisture-absorbing fiber felt; 22, outward protruding bin; 23, exhaust pipe; 24, one-way valve. Detailed implementation manners

[0033] Embodiment:

[0034] As Figures 1 to 14 shown in the PCB waterproof circuit board, including a PCB board body 1, on which components are arranged and soldered; the components include large-sized components 2 whose height exceeds 6 mm above the top surface of the PCB board body 1 after soldering and small-sized components 3 whose height above the top surface of the PCB board body 1 after soldering does not exceed 6 mm; further comprising:

[0035] A sealing seat 4, which is fixed around the large-sized component 2; the inner side of the sealing seat 4 is a cavity with both ends hollow, and a retaining edge 5 is integrally formed on the inner side of the sealing seat 4. The large-sized component 2 is embedded in the inner side of the sealing seat 4 and pressed against the retaining edge 5, and the large-sized component 2 is soldered to the PCB board body 1; a glue injection through hole 6 is opened on the PCB board body 1 inside the sealing seat 4;

[0036] A potting colloid 7, which is poured into the sealed cavity formed by the large-sized component 2, the sealing seat 4, the retaining edge 5 and the PCB board body 1 through the glue injection through hole 6; the potting colloid 7 covers the bottom surface of the large-sized component 2;

[0037] Waterproof coating, the waterproof coating includes a first waterproof coating 8 and a second waterproof coating 9; after the small-sized components 3 are soldered to the PCB board body 1, the first waterproof coating 8 is coated on the top surface of the PCB board body 1 and the outside of the small-sized components 3; after all the components are soldered, the second waterproof coating 9 is coated on the bottom surface of the PCB board body 1.

[0038] When processing a PCB waterproof circuit board, first perform PCB wiring according to the circuit schematic diagram. Then, process the PCB board body 1, punch holes in the PCB board body 1, and coat a vacuum impregnated varnish coating. Next, solder the small-sized components 3 to the PCB board body 1. After completion of soldering, coat the top surface of the PCB board body 1 and the outside of the small-sized components 3 with the first waterproof coating 8 to provide waterproof protection for the PCB board body 1 and the small-sized components 3 through the first waterproof coating 8. Then install the sealing seat 4 and fix the sealing seat 4 around the installation position of the large-sized components 2. After the sealing seat 4 is installed on the top surface of the PCB board body 1, then solder the large-sized components 2 (large-sized components with external leads, large-sized components with internal leads, voltage regulators, sensors, etc.) to the PCB board body 1 and perform circuit testing. After passing the test, perform the operation of pouring potting compound 7. Align the pouring head of the potting equipment with the injection through-hole 6, and then inject the potting compound 7 into the sealed cavity formed by the large-sized components 2, the sealing seat 4, the retaining edge 5, and the PCB board body 1. Fill and coat the large-sized components 2 with the potting compound 7 to provide waterproof protection for the lower part of the device body and the leads of the large-sized components 2, so that the PCB waterproof circuit board has waterproof effect.

[0039] The waterproof coating is a nano waterproof coating; the two sides of the PCB board body 1 are provided with a vacuum impregnated varnish coating; through the vacuum impregnated varnish coating, glue can be applied to both sides of the PCB board body 1 to protect the circuit traces on the PCB board body 1.

[0040] The sealing seat 4 is fixed to the PCB board body 1 by adhesion or soldering; during soldering, it is necessary to pre-reserve the pin mounting holes for the sealing seat 4 when wiring the PCB board body 1 in advance. Finally, use the sealing seat 4 as a component and directly solder it to the PCB board body 1; when using the adhesion method, directly apply adhesive to the bottom of the sealing seat 4, and finally, bond the sealing seat 4 to the PCB board body 1.

[0041] When the leads of the large-sized components 2 are located outside the component body, the retaining edge 5 is a horizontal bar, and the potting compound 7 is poured in from the inner top of the sealing seat 4 and coats the leads of the large-sized components 2; the bottom of the large-sized components 2 is limited by the retaining edge 5, so that the leads of the large-sized components 2 can be kept at a set height, enabling the potting compound 7 to smoothly enter and fill the inside of the sealing seat 4.

[0042] The PCB board body 1 is installed on an external waterproof unit, which includes an upper housing 10 and a lower housing 11. A plurality of ear seats 12 are integrally formed on the mutually adjacent sides of the outer parts of the upper housing 10 and the lower housing 11; the ear seats 12 are fastened by bolts and nuts, and a sealing ring is arranged between the upper housing 10 and the lower housing 11; an inner ring seat 13 is integrally formed on the inner side of the upper housing 10; a ring groove 14 is formed on the inner ring seat 13, a plurality of blind holes are formed along the inner edge of the top surface of the PCB board body 1, and a pressing ring 15 is adhesively fixed along the inner edge of the top surface of the PCB board body 1; an inserting column 16 that fits into the blind holes is arranged on the pressing ring 15; the pressing ring 15 is inserted into the inner side of the ring groove 14; an epoxy resin sealing layer is arranged between the outside of the PCB board body 1 and the inside of the upper housing 10; a cable waterproof assembly is arranged at the end of the upper housing 10; the cable 17 passes through the inside of the cable waterproof assembly, and the cable 17 is electrically connected to the PCB board body 1; during installation, first, glue is applied to the pressing ring 15 and the inner edge of the top surface of the PCB board body 1, then, the cable 17 on the PCB board body 1 is led out from the cable waterproof assembly; then, the inserting column 16 of the pressing ring 15 is aligned and fitted into the blind holes of the PCB board body 1, so that a sealing surface is formed on the fitting surface of the PCB board body 1 and the pressing ring 15; then, the pressing ring 15 is aligned and fitted into the ring groove 14 of the inner ring seat 13, and finally, an epoxy resin sealing layer is obtained by coating and curing between the outside of the PCB board body 1 and the inside of the upper housing 10; thus, a sealed cavity is formed between the inner side of the upper housing 10 and the PCB board body 1; finally, the upper housing 10 and the lower housing 11 are aligned, the sealing ring is inserted, and finally, the ear seats 12 on the upper housing 10 and the lower housing 11 are fastened together by bolts and nuts.

[0043] The cable waterproof assembly includes a waterproof joint 18 fitted and fixed at the end of the upper housing 10; a screw sleeve 19 is integrally formed on the upper housing 10 outside the waterproof joint 18, a sealing head 20 is screwed on the screw sleeve 19, and the cable 17 passes through the sealing head 20 movably; potting colloid 7 is arranged in the space formed by the screw sleeve 19 and the sealing head 20; during operation, first, the connection of the PCB board body 1, the cable 17 and the waterproof joint 18 is completed, then, the cable 17 passes through the sealing head 20, and potting colloid 7 is injected into the screw sleeve 19 through the glue injection hole on the screw sleeve 19; thus, the connection part of the waterproof joint 18 and the cable 17 can be waterproof potted.

[0044] The inner surface of the upper housing 10 is bonded with a moisture-absorbing fiber felt 21; an outwardly convex chamber 22 is integrally formed on the outer top surface of the upper housing 10; an exhaust pipe 23 is fitted and fixed to the inner surface of the moisture-absorbing fiber felt 21 in the upper housing 10; the exhaust pipe 23 is connected to the outside of the outwardly convex chamber 22, and two mutually connected exhaust valves are arranged on the exhaust pipe 23, and the exhaust valves are connected to the PCB board 1; a pressure transmitter and a humidity transmitter are arranged on the PCB board 1; an inflation assembly is arranged on the upper housing 10; when the humidity transmitter monitors that the water vapor inside the external waterproof unit reaches the set value, first open the external exhaust valve to make the pipe section from the outside of the exhaust pipe 23 to the output end of the closed exhaust valve in the atmospheric pressure state, then close the external exhaust valve and open the internal exhaust valve. Since the pressure of the external waterproof unit is greater than the atmospheric pressure, the moisture inside the external waterproof unit can be discharged into the exhaust pipe 23 through the moisture-absorbing fiber felt 21. After the exhaust is completed, the exhaust valve is closed; the moisture-absorbing fiber felt 21 continuously absorbs moisture. During exhaust, the moisture on the moisture-absorbing fiber felt 21 can be carried away by the air flow, so as to maintain the moisture absorbency of the moisture-absorbing fiber felt 21; when the pressure transmitter detects that the pressure is lower than the set value, the PCB board 1 sends a signal indicating that inflation is needed, and the inflation assembly inflates the inside of the external waterproof unit, and uses the pressure difference between the inside and the outside of the external waterproof unit to prevent water vapor from entering the inside of the external waterproof unit.

[0045] The inflation assembly is an inflation nozzle 22; during operation, compressed air is filled into the external waterproof unit through the inflation nozzle 22 to make the internal air pressure of the external waterproof unit reach the set pressure.

[0046] The inflation assembly includes a pump set fixed to the inner side of the upper housing 10, and the input end of the pump set is connected to the output end of the exhaust pipe 23; two one-way valves 24 are connected in parallel to the output end of the exhaust pipe 23, and the opening directions of the one-way valves 24 are opposite; the output end of the pump set is in a hollow state; the pump set is connected to the PCB board 1; when it is necessary to fill the inside of the external waterproof unit with compressed air, the pump set is started, and the air outside the external waterproof unit is filled into the exhaust pipe 23 through one one-way valve 24, and then filled into the inside of the external waterproof unit through the pump set; when the internal pressure of the external waterproof unit reaches the set pressure value, the pump set stops working; when the pump set inflates the external waterproof unit, the outlet of the pump set faces the humidity transmitter. When the pump set is started, the humidity transmitter performs real-time humidity sampling. When the humidity exceeds the set value, the inflation stops, and inflation is carried out again after a delay until a suitable inflation environment is monitored for inflation. When multiple humidity samplings do not pass, a manual trigger inflation instruction is issued.

[0047] The above embodiments are only the preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made according to the structures, features, and principles described in the scope of the present invention application are included in the scope of the present invention application.

Claims

1. A waterproof PCB circuit board, comprising a PCB board body, on which components are arranged and soldered; characterized in that: The components include large-sized components with a height exceeding 6 mm above the top surface of the PCB board after welding and small-sized components with a height not exceeding 6 mm above the top surface of the PCB board after welding; and further include: A sealing seat fixed around the large-sized component; the inner side of the sealing seat is a cavity hollow at both ends, and a retaining edge is integrally formed on the inner side of the sealing seat. The large-sized component is embedded in the inner side of the sealing seat and pressed against the retaining edge, and the large-sized component is welded to the PCB board. A glue injection through-hole is provided on the PCB board inside the sealing seat. Potting colloid, which is poured into the sealed cavity formed by the large-sized component, the sealing seat, the retaining edge and the PCB board through the glue injection through-hole; the potting colloid covers the bottom surface of the large-sized component. A waterproof coating, which includes a first waterproof coating and a second waterproof coating; after the small-sized component is welded to the PCB board, the first waterproof coating is applied to the top surface of the PCB board and the outside of the small-sized component; after all the components are welded, the second waterproof coating is applied to the bottom surface of the PCB board.

2. The PCB waterproof circuit board according to claim 1, wherein: The waterproof coating is a nano waterproof coating; a vacuum impregnated varnish coating is provided on both sides of the PCB board.

3. The PCB waterproof circuit board according to claim 1, characterized in that: The sealing seat is fixed to the PCB board by adhesion or welding.

4. The PCB waterproof circuit board according to claim 1, characterized in that: When the pins of the large-sized component are outside the component body, the retaining edge is a cross bar, and the potting colloid is poured in from the top of the inner side of the sealing seat and covers the pins of the large-sized component.

5. The PCB waterproof circuit board according to claim 1, characterized in that: The PCB board is installed on an external waterproof unit, which includes an upper shell and a lower shell. On the outer sides of the upper shell and the lower shell, a plurality of ear seats are integrally formed on the side close to each other; the ear seats are fastened by bolts and nuts, and a sealing ring is provided between the upper shell and the lower shell; an inner ring seat is integrally formed on the inner side of the upper shell; a ring groove is provided in the inner ring seat, a plurality of blind holes are provided in the inner edge of the top surface of the PCB board, and a pressing ring is adhesively fixed to the inner edge of the top surface of the PCB board; an insertion post fitting into the blind hole is provided on the pressing ring; the pressing ring is inserted into the inner side of the ring groove; an epoxy resin sealing layer is provided between the outside of the PCB board and the inside of the upper shell; a cable waterproof component is provided at the end of the upper shell; the cable passes through the inside of the cable waterproof component, and the cable is electrically connected to the PCB board.

6. The PCB waterproof circuit board according to claim 5, characterized in that: The cable waterproof component includes a waterproof connector fitted and fixed to the end of the upper shell; a screw sleeve is integrally formed on the upper shell outside the waterproof connector, and a sealing head is screwed onto the screw sleeve. The cable passes through the sealing head movably, and potting colloid is provided in the space formed by the screw sleeve and the sealing head.

7. The PCB waterproof circuit board according to claim 5, wherein: A moisture-absorbing fiber felt is adhesively attached to the inner surface of the upper shell; an outwardly protruding chamber is integrally formed on the top surface of the outside of the upper shell; an exhaust pipe is fitted and fixed to the inner surface of the moisture-absorbing fiber felt in the upper shell; the exhaust pipe is connected to the outside of the outwardly protruding chamber, and two mutually connected exhaust valves are provided on the exhaust pipe, and the exhaust valves are connected to the PCB board; a pressure transmitter and a humidity transmitter are provided on the PCB board; an inflation component is provided on the upper shell.

8. The PCB waterproof circuit board according to claim 7, wherein: The inflation component is an inflation nozzle.

9. The PCB waterproof circuit board according to claim 7, wherein: The inflatable assembly includes a pump set fixed to the inner side of the upper housing. The input end of the pump set is connected to the output end of the exhaust pipe. Two one-way valves are connected in parallel to the output end of the exhaust pipe, and the opening directions of the one-way valves are opposite. The output end of the pump set is in a hollow state. The pump set is connected to the PCB board.

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