Shielding device of low-thermal-conductivity packaging chip and assembly process

Abstract

The invention relates to a shielding device of a low-heat-conductivity packaging chip and an assembling technology, the shielding device of the low-heat-conductivity packaging chip comprises a main board and a lower shell, the main board is provided with a chip, the lower shell is provided with a sealing structure integrally formed with the lower shell, a condensation sheet is installed in the sealing structure, and the condensation sheet is provided with a shielding layer. The main board is arranged on the lower shell in a covering mode, a sealing cavity is formed by the main board and the sealing structure, the chip is embedded in the sealing cavity and attached to the condensation piece, and the sealing cavity is filled with sealant. The beneficial effects of the invention are that generation of condensed water can be avoided, the service life of the chip is prolonged, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chip heat dissipation, and particularly relates to a shielding device and an assembly process for a chip with low thermal conductivity encapsulation. Background Art

[0002] In the field of automotive electronics, the thermal conductivity of chips with low thermal conductivity encapsulation (such as resin encapsulated chips) is lower than that of metals or other heat dissipation materials, resulting in low heat dissipation efficiency. Especially during high-load operation, heat is difficult to transfer and dissipate, seriously affecting the stability and lifespan of the chip. Currently, common chip heat dissipation methods include heat sinks, fans, heat pipes, etc. Heat sinks are suitable for most heat dissipation requirements, but their heat dissipation efficiency depends on the surface area and material thermal conductivity; fan heat dissipation accelerates heat dissipation through forced air convection, and can effectively transfer heat from the heat source to the heat sink or radiator, but it occupies a large space and has a high working noise, and the dust in the air duct needs to be cleaned regularly; heat pipes are currently a relatively efficient heat transfer technology, which reduces the chip temperature through liquid circulation, but their manufacturing and integration processes are relatively complex and the cost is high.

[0003] However, with the expansion of the chip market scale and the growth of chip packaging methods and their power consumption, traditional methods such as fans and heat sinks cannot meet the heat dissipation requirements of chips. To quickly reduce the high temperature generated during chip operation, a cold condensing sheet with a lower temperature is used to increase the temperature difference between the chip surface and the condensing sheet, and the heat generated during chip operation is forced to pass through the encapsulation material with lower thermal conductivity to the low-temperature area of the condensing sheet, so as to achieve the purpose of rapid heat dissipation and ensure the normal operation of the chip. However, during the specific heat dissipation process, the large temperature difference between the low-temperature layer of the condensing sheet and the high-temperature layer generated by the chip operation may generate condensed water, which may further cause problems such as electrical short circuits or crossovers, and chip surface corrosion. Summary of the Invention

[0004] The purpose of the present invention is to provide a shielding device and an assembly process for a chip with low thermal conductivity encapsulation, which can avoid the generation of condensed water, extend the service life of the chip, and reduce production costs.

[0005] A shielding device for a chip with low thermal conductivity encapsulation includes a main board and a lower housing. A chip is provided on the main board. The lower housing is provided with a sealing structure integrally formed with the lower housing. A condensing sheet is installed in the sealing structure. The main board is covered on the lower housing and forms a sealed cavity with the sealing structure. The chip is embedded in the sealed cavity and is in contact with the condensing sheet. The sealed cavity is filled with sealant.

[0006] In the above solution, the sealing structure is integrally formed with the lower housing, which has a simple structure and low cost. The main board is covered on the lower housing and forms a sealed cavity with the sealing structure. The chip is located in the sealed cavity and is attached to the condensation fin. The condensation fin is used to dissipate heat from the chip, thus effectively solving the problem of insufficient heat dissipation of chips with low thermal conductivity packaging. Sealant is filled in the sealed cavity, and air is discharged from the sealed cavity, so that the chip and the condensation fin will not come into contact with air, thereby solving the problem of condensation water generated due to excessive temperature difference during the heat dissipation process of the chip. This can protect the chip and extend its service life, and at the same time meet the shielding ability required for the normal operation of the chip. There is no need to design a separate shielding structure, effectively reducing costs.

[0007] Further, the sealing structure includes a groove and an outer peripheral wall extending towards the main board. The outer peripheral wall is hermetically connected to the main board, and the condensation fin is installed in the groove.

[0008] In the above solution, the outer peripheral wall is hermetically connected to the main board, so that the groove and the main board form a sealed cavity, which can ensure effective isolation of the chip and the condensation fin from the outside. The condensation fin is installed in the groove and is closely attached to the chip, which can effectively absorb and dissipate the heat generated by the chip, improving the heat dissipation efficiency. The sealing structure itself has a certain shielding effect, reducing the need for an additional shielding layer, simplifying the design, and reducing costs.

[0009] Further, a wire passing hole is provided at one end of the outer peripheral wall, and the wire harness connected to the condensation fin passes through the wire passing hole and is electrically connected to the main board.

[0010] In the above solution, the condensation fin is fixed on the sealing structure, and the wire harness connected to it passes through the wire passing hole and is connected to the main board to ensure the normal operation of the condensation fin. The design of the wire passing hole makes the arrangement and fixation of the wire harness simpler, reducing complex wiring and fixing steps. When filling the sealant, the sealant at the position of the wire passing hole quickly cools and solidifies to seal the wire passing hole, ensuring the complete sealing of the sealed cavity.

[0011] Further, an injection port is provided at one end of the groove, and the injection port is communicated with a through hole on the end face of the lower housing away from the main board.

[0012] In the above solution, when filling the sealant, the sealant can be directly injected through the through hole on the end face of the lower housing. The sealant enters the sealed cavity through the injection port, thereby discharging the air in the sealed cavity. The through hole and the injection port are integrally formed with the lower housing, enhancing the stability of the sealing structure and reducing potential leakage points.

[0013] Further, a plurality of positioning posts are provided at the top end of the outer peripheral wall, and positioning holes are provided on the main board corresponding to the positions of the positioning posts.

[0014] In the above solution, the cooperation between the positioning posts and the positioning holes ensures the precise alignment of the main board on the outer peripheral wall, avoiding possible offsets or misalignments during the assembly process, thereby improving the assembly accuracy, making the installation process of the main board simple and fast, reducing complex alignment steps, and the design of the positioning posts and positioning holes ensures the consistency of the assembly process for all products, reducing errors caused by manual operations.

[0015] Furthermore, a number of threaded holes are provided on the outer peripheral wall, and connection holes are provided on the main board corresponding to the positions of the threaded holes.

[0016] In the above solution, through the cooperation of the threaded holes and the connection holes, screws are used to fix the main board on the outer peripheral wall, providing a stable mechanical connection, further enhancing the structural stability, and thus ensuring the sealing performance of the sealed cavity.

[0017] Furthermore, a sealing glue is coated on the area where the main board is connected to the sealing structure.

[0018] In the above solution, the sealing glue can form a sealing layer between the main board and the sealing structure, effectively preventing the intrusion of moisture, dust and other pollutants. The sealing glue not only provides a sealing function, but also enhances the mechanical connection between the main board and the sealing structure, improving the stability of the overall structure.

[0019] Furthermore, it further includes an upper housing, and the upper housing is covered on the main board and connected to the lower housing.

[0020] In the above solution, the upper housing covering the main board and being connected to the lower housing can further ensure the stability of the main board, and at the same time can protect the main board and other internal components from external impacts, scratches and damages, enhancing the integrity of the overall structure of the chip shielding device.

[0021] An assembly process for assembling the shielding device of the low thermal conductivity packaged chip as described in any one of the above solutions includes the following steps: fixing the condensation sheet in the sealing structure, and passing the wire harness through the wire passing holes on the outer peripheral wall to electrically connect the wire harness to the main board; coating a sealing glue on the area where the main board is connected to the sealing structure, and hermetically connecting the main board and the sealing structure through the cooperation of the positioning posts and the positioning holes to form a sealed cavity; filling the sealed cavity with a sealing glue through the injection port and discharging the air in the sealed cavity.

[0022] In the above solution, the condensation sheet can be fixed in the sealing structure by glue or the like, and the wire harness can be passed through the wire passing hole so that the wire harness can be electrically connected to the main board, which is used to ensure the normal operation of the condensation sheet. Sealant is applied to the area where the main board is connected to the sealing structure to effectively prevent the intrusion of moisture and dust. Through the cooperation of the positioning posts and positioning holes, the accurate alignment and firm connection of the main board and the sealing structure are achieved, ensuring the formation of the sealed cavity. Sealing glue is filled into the sealed cavity through the injection port, which can effectively discharge the air in the cavity and ensure the sealing performance of the sealed cavity. Through strict connection and sealing steps, the generation of condensed water can be avoided, thereby extending the service life of the chip.

[0023] Further, before the step of filling the sealing glue into the sealed cavity through the injection port and discharging the air in the sealed cavity, it also includes fixing the main board and the sealing structure by locking the fasteners on the connection holes and threaded holes; after the step of filling the sealing glue into the sealed cavity through the injection port and discharging the air in the sealed cavity, it also includes covering the upper shell on the main board and clamping the main board and locking it on the lower shell through the fasteners.

[0024] In the above solution, by locking the fasteners on the connection holes and threaded holes, the firm fixation of the main board and the sealing structure is achieved, enhancing the mechanical stability of the structure. The locking of the fasteners can effectively resist the vibration and impact of the device, ensuring the stability of the main board and the sealing structure in a dynamic environment; after filling the sealing glue into the sealed cavity through the injection port, by covering the upper shell on the main board and locking it with the lower shell through the fasteners, a complete outer shell encapsulation is formed.

[0025] The shielding device and assembly process of a low thermal conductivity encapsulated chip according to the present invention have the beneficial effects of being able to avoid the generation of condensed water, extending the service life of the chip, and reducing production costs. The sealing structure is integrally formed with the lower shell, with a simple structure and low cost. The main board is covered on the lower shell and forms a sealed cavity with the sealing structure. The chip is located in the sealed cavity and fits with the condensation sheet. The condensation sheet is used to dissipate heat from the chip, thus effectively solving the problem of insufficient heat dissipation of the low thermal conductivity encapsulated chip. Sealing glue is filled into the sealed cavity, and the air is discharged from the sealed cavity, so that the chip and the condensation sheet will not come into contact with the air, thereby solving the problem of condensed water generated due to excessive temperature difference during the heat dissipation process of the chip, which can play a role in protecting the chip to extend its service life, and at the same time meet the shielding ability required for the normal operation of the chip. There is no need to design a separate shielding structure, effectively reducing costs. Description of the Drawings

[0026] Figure 1 It is an exploded view of the shielding device of a low thermal conductivity encapsulated chip according to an embodiment.

[0027] Figure 2Overall structural diagram of the shielding device for a low thermal conductivity packaged chip of an embodiment.

[0028] Figure 3 Schematic diagram of the lower housing and the sealing structure of an embodiment.

[0029] Figure 4 Schematic diagram of the main board and the chip structure of an embodiment.

[0030] Figure 5 Schematic diagram of the copper exposed area and the connection hole positions on the main board of an embodiment.

[0031] Figure 6 Schematic diagram of the through-hole structure of an embodiment.

[0032] Figure 7 Schematic diagram of the assembly process steps of an embodiment.

[0033] Explanation of the reference numerals in the drawings: 1. Lower housing; 2. Main board; 21. Copper exposed area; 3. Sealing structure; 31. Groove; 32. Outer peripheral wall; 4. Condensing sheet; 5. Chip; 6. Threading hole; 7. Wiring harness; 8. Positioning post; 9. Positioning hole; 10. Upper housing; 11. Through-hole; 12. Injection port; 13. Threaded hole; 14. Connection hole. Detailed implementation manners

[0034] The shielding device and the assembly process of a low thermal conductivity packaged chip of the present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0035] As Figures 1 to 4 shown, in a preferred embodiment, a shielding device for a low thermal conductivity packaged chip 5 of the present invention includes a main board 2 and a lower housing 1. A chip 5 is provided on the main board 2. A sealing structure 3 integrally formed with the lower housing 1 is provided on the lower housing 1. A condensing sheet 4 is installed in the sealing structure 3. The main board 2 is covered on the lower housing 1 and forms a sealed cavity with the sealing structure 3. The chip 5 is embedded in the sealed cavity and is in contact with the condensing sheet 4. The sealed cavity is filled with a sealing glue. The sealing structure 3 is integrally formed with the lower housing 1, with a simple structure and low cost. The main board 2 is covered on the lower housing 1 and forms a sealed cavity with the sealing structure 3. The chip 5 is located in the sealed cavity and is in contact with the condensing sheet 4. The condensing sheet 4 is used to dissipate heat from the chip 5, thus effectively solving the problem of insufficient heat dissipation of the low thermal conductivity packaged chip. The sealed cavity is filled with a sealing glue, which can be a plastic. The air is discharged from the sealed cavity, so that the chip 5 and the condensing sheet 4 will not come into contact with the air, thus solving the problem of condensed water generated due to excessive temperature difference during the heat dissipation process of the chip 5, thereby being able to protect the chip 5 and extend its service life. At the same time, it also meets the shielding ability required for the normal operation of the chip 5, and there is no need to design a separate shielding structure, effectively reducing the cost.

[0036] As shown in Figure 1 and Figure 3 In some embodiments, as shown, the sealing structure 3 includes a groove 31 and an outer peripheral wall 32 extending towards the main board 2. The outer peripheral wall 32 is sealingly connected to the main board 2, and the condensation fin 4 is installed in the groove 31. The outer peripheral wall 32 is sealingly connected to the main board 2, so that the groove 31 and the main board 2 form a sealed cavity, thereby ensuring effective isolation of the chip 5 and the condensation fin 4 from the outside. The condensation fin 4 is installed in the groove 31 and is in close contact with the chip 5, which can effectively absorb and dissipate the heat generated by the chip 5, improving the heat dissipation efficiency. The sealing structure 3 itself has a certain shielding effect, reducing the need for an additional shielding layer, simplifying the design, and reducing the cost.

[0037] Specifically, the condensation fin 4 can be adhesively bonded in the groove 31 of the sealing structure 3. The overall structure of the outer peripheral wall 32 and the groove 31 is a rectangular structure, which is convenient for molding.

[0038] As shown in Figure 3 In some embodiments, as shown, a wire passing hole 6 is provided at one end of the outer peripheral wall 32, and a wire harness 7 connected to the condensation fin 4 passes through the wire passing hole 6 and is electrically connected to the main board 2. The condensation fin 4 is fixed on the sealing structure 3, and the wire harness 7 connected to it passes through the wire passing hole 6 and is connected to the main board 2 to ensure the normal operation of the condensation fin 4. The design of the wire passing hole 6 makes the arrangement and fixation of the wire harness 7 simpler, reducing complex wiring and fixation steps. When filling the sealing glue, the sealing glue at the position of the wire passing hole 6 quickly cools and solidifies to seal the wire passing hole 6, ensuring the complete sealing of the sealed cavity.

[0039] The diameter of a single wire harness 7 is about 0.2 mm, and the height of the wire passing hole 6 is about 1 mm. When filling the sealing glue, a small amount of sealing glue will overflow, but the sealing glue can quickly cool to block the wire passing hole 6, ensuring the sealing of the sealed cavity.

[0040] As shown in Figure 3 and Figure 6 In some embodiments, as shown, an injection port 12 is provided at one end of the groove 31, and the injection port 12 is communicated with a through hole 11 on the end face of the lower housing 1 away from the main board 2. When filling the sealing glue, the sealing glue can be directly injected through the through hole 11 on the end face of the lower housing 1. The sealing glue enters the sealed cavity through the injection port 12, thereby discharging the air in the sealed cavity. The through hole 11 and the injection port 12 are integrally formed with the lower housing 1, enhancing the stability of the sealing structure 3 and reducing potential leakage points.

[0041] As shown in Figure 3 and Figure 4As shown, in some embodiments, a plurality of positioning posts 8 are provided at the top of the outer peripheral wall 32, and positioning holes 9 are provided on the main board 2 corresponding to the positions of the positioning posts 8. The cooperation between the positioning posts 8 and the positioning holes 9 ensures the precise alignment of the main board 2 on the outer peripheral wall 32, avoiding possible offsets or misalignments during the assembly process, thereby improving the assembly accuracy, making the installation process of the main board 2 simple and fast, reducing complex alignment steps, and the design of the positioning posts 8 and the positioning holes 9 ensures the consistency of the assembly process for all products and reduces errors caused by manual operations.

[0042] As Figures 3 to 5 shown, in some embodiments, a plurality of threaded holes 13 are provided on the outer peripheral wall 32, and connection holes 14 are provided on the main board 2 corresponding to the positions of the threaded holes 13. Through the cooperation of the threaded holes 13 and the connection holes 14, the main board 2 is fixed on the outer peripheral wall 32 using screws, providing a stable mechanical connection, further enhancing the structural stability, and thus ensuring the sealing performance of the sealed cavity.

[0043] In this embodiment, the outer peripheral wall 32 has a certain thickness, which facilitates the setting of the threaded holes 13 on the outer peripheral wall 32.

[0044] As Figures 3 to 5 shown, in some embodiments, a sealing glue is coated on the area where the main board 2 is connected to the sealing structure 3. The area where the main board 2 is connected to the sealing structure 3 is the copper-exposed area 21. Coating the sealing glue on the copper-exposed area 21 can form a sealing layer between the main board 2 and the sealing structure 3, effectively preventing the intrusion of moisture, dust, and other contaminants. The sealing glue not only provides a sealing function but also enhances the mechanical connection between the main board 2 and the sealing structure 3, improving the stability of the overall structure.

[0045] As Figure 1 and Figure 2 shown, in some embodiments, it further includes an upper housing 10, and the upper housing 10 covers the main board 2 and is connected to the lower housing 1. The upper housing 10 covering the main board 2 and being connected to the lower housing 1 can further ensure the stability of the main board 2, and at the same time can protect the main board 2 and other internal components from external impacts, scratches, and damages, enhancing the integrity of the overall structure of the chip 5 shielding device.

[0046] As Figure 7 shown, an assembly process for assembling the shielding device of the low-thermal-conductivity packaged chip 5 as described in any one of the above embodiments includes the following steps: S1. Fix the condensation sheet 4 in the sealing structure 3, and pass the wire harness 7 through the wire passing hole 6 on the outer peripheral wall 32 to electrically connect the wire harness 7 to the main board 2; S2. Coat a sealing glue on the area where the main board 2 is connected to the sealing structure 3, and hermetically connect the main board 2 and the sealing structure 3 through the cooperation of the positioning posts 8 and the positioning holes 9 to form a sealed cavity; S3. Fix the main board 2 and the sealing structure 3 by locking the fasteners to the connection holes 14 and the threaded holes 13; S4. Fill the sealing cavity with sealant through the injection port 12 and discharge the air in the sealing cavity; S5. Cover the upper housing 10 on the main board 2 and clamp the main board 2 to lock it to the lower housing 1 through the fasteners.

[0047] The condensation fin 4 can be fixed in the sealing structure 3 with glue or the like. Pass the wiring harness 7 through the wire passing hole 6 so that the wiring harness 7 can be electrically connected to the main board 2 to ensure the normal operation of the condensation fin 4. Apply sealing glue to the area where the main board 2 is connected to the sealing structure 3 to effectively prevent the intrusion of moisture and dust. Through the cooperation of the positioning posts 8 and the positioning holes 9, the accurate alignment and firm connection of the main board 2 and the sealing structure 3 are achieved, ensuring the formation of the sealing cavity. Fill the sealing cavity with sealant through the injection port 12, which can effectively discharge the air in the cavity and ensure the sealing performance of the sealing cavity. Through strict connection and sealing steps, the generation of condensed water can be avoided, thereby extending the service life of the chip 5.

[0048] By locking the fasteners to the connection holes 14 and the threaded holes 13, the firm fixation of the main board 2 and the sealing structure 3 is achieved, enhancing the mechanical stability of the structure. The locking of the fasteners can effectively resist the vibration and impact of the device, ensuring the stability of the main board 2 and the sealing structure 3 in a dynamic environment; after filling the sealing cavity with sealant through the injection port 12, cover the upper housing 10 on the main board 2 and lock it to the lower housing 1 through the fasteners to form a complete outer shell package.

[0049] For the working principle and process of the shielding device and assembly process for encapsulating a chip with low thermal conductivity in the present invention, the main board 2 and the sealing structure 3 on the lower housing 1 are combined to form a sealing cavity. The condensation fin 4 is installed in the sealing cavity, and the condensation fin 4 is attached to the chip 5 on the main board 2 to dissipate heat from the chip 5. Inject sealant such as plastic into the sealing cavity to isolate the chip 5 and the condensation fin 4 from the air, avoid the generation of condensed water, protect the chip 5, and at the same time meet the shielding ability required for the normal operation of the chip 5.

[0050] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless specifically defined otherwise.

[0052] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] Although the description of the present invention is made in conjunction with the above specific embodiments, it is obvious that those skilled in the art can make many substitutions, modifications, and variations based on the above content. Therefore, all such substitutions, improvements, and variations are included within the spirit and scope of the appended claims.

Claims

1. A shielding device for a low thermal conductivity packaged chip, characterized in that: It includes a mainboard and a lower shell, the mainboard is provided with a chip, the lower shell is provided with a sealing structure integrally formed with the lower shell, a condensing sheet is installed in the sealing structure, the mainboard cover is provided on the lower shell and forms a sealed cavity with the sealing structure, the chip is embedded in the sealed cavity and fits with the condensing sheet, and the sealed cavity is filled with sealant.

2. The shielding device for low thermal conductivity packaged chips according to claim 1, characterized in that: The sealing structure comprises a groove and a peripheral wall extending toward the main board, the peripheral wall is sealingly connected to the main board, and the condensing sheet is installed in the groove.

3. The shielding device for low thermal conductivity packaged chips according to claim 2, characterized in that: A wire threading hole is provided at one end of the outer peripheral wall, and the wire harness connected to the condenser plate passes through the wire threading hole and is electrically connected to the main board.

4. The shielding device for low thermal conductivity packaged chips according to claim 2, characterized in that: An injection port is provided at one end of the groove, and the injection port is communicated with a through hole on the end surface of the lower shell away from the main board.

5. The shielding device for low thermal conductivity packaged chips according to claim 2, characterized in that: A plurality of positioning posts are disposed on the top end of the outer peripheral wall, and positioning holes are disposed on the main board at positions corresponding to the positioning posts.

6. The shielding device for low thermal conductivity packaged chips according to claim 2, characterized in that: The outer peripheral wall is provided with a plurality of threaded holes, and the main board is provided with connecting holes at positions corresponding to the threaded holes.

7. The shielding device for low thermal conductivity packaged chips according to claim 1, characterized in that: The area where the mainboard is connected to the sealing structure is coated with sealing glue.

8. The shielding device for low thermal conductivity packaged chips according to claim 1, characterized in that: It also includes an upper shell, which is covered on the main board and connected to the lower shell.

9. An assembly process, characterized in that: The shielding device for assembling the low thermal conductivity packaged chip as claimed in any one of claims 1 to 8 comprises the following steps: The condensing sheet is fixed in the sealing structure, and the wiring harness is passed through the threading hole on the outer peripheral wall to electrically connect the wiring harness with the main board; Sealing glue is applied to the area where the main board and the sealing structure are connected, and the main board and the sealing structure are sealed and connected to form a sealing cavity through the cooperation of the positioning column and the positioning hole; The sealing cavity is filled with sealant through the injection port, and the air in the sealing cavity is exhausted.

10. The assembly process according to claim 9, characterized in that: Before the step of filling the sealing cavity with sealant through the injection port and exhausting the air in the sealing cavity, the main board and the sealing structure are fixed by locking fasteners on the connecting holes and the threaded holes; After the steps of filling the sealing cavity with sealant through the injection port and exhausting the air in the sealing cavity, the method further includes placing the upper shell cover on the main board and clamping the main board to be locked on the lower shell by fasteners.

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