Radar device and method for manufacturing a radar device

Abstract

A radar apparatus is provided for an automatic driving (AD) application or an advanced driver assistance system (ADAS) application of a vehicle. The apparatus includes a housing having a base and a cover, a radar unit mounted on a printed circuit board (PCB), and a shield covering the radar unit and configured to provide EMC (Electromagnetic Compatibility) shielding to the radar unit. The shield is fixedly attached to the inside bottom of the base. The base is provided with a support structure comprising a plurality of support elements configured to provide support to the PCB and / or the shield.

Description

Technical Field

[0001] The present disclosure relates to a radar device for autonomous driving (AD) or advanced driver assistance system (ADAS) applications of a vehicle, and a method for manufacturing the radar device. The radar device includes a housing, a radar unit, and a shield. Background Art

[0002] To ensure optimal performance of radar equipment, the heat generated by the radar must be dissipated externally. This heat is typically dissipated using a heat sink located within the radar equipment. Current solutions utilize aluminum die-cast or stamped sheet metal heat sinks. These heat sinks serve both as heat dissipation devices and as EMC shielding elements. In stamped sheet metal heat sinks, EMC metal springs are soldered to the heat sink and provide an electrical connection between the heat sink and the ground path on the PCB.

[0003] During assembly of the radar device, the heat sink is typically inserted before the PCB includes the radar unit and is subsequently compressed during a PCB press fit assembly.

[0004] Heat sinks significantly increase the manufacturing cost of radar units due to their relatively high unit price. In this regard, die-cast heat sinks are even more expensive than stamped sheet metal heat sinks. Therefore, a previous solution to reduce heat sink costs has been to replace die-cast heat sinks with stamped sheet metal heat sinks. While this reduces the unit price, stamped sheet metal heat sinks present problems during press-fit assembly due to their lower stiffness compared to die-cast heat sinks.

[0005] Therefore, there is a need for a radar device that is cost-effective, easy to assemble, and reliable in operation. Summary of the Invention

[0006] The present disclosure provides in a first aspect a radar device according to the independent claim and in a second aspect a method for manufacturing a radar device according to the independent claim. Embodiments are given in the dependent claims, the description and the drawings.

[0007] In a first aspect, the present disclosure relates to a radar device for use in autonomous driving (AD) applications or advanced driver assistance system (ADAS) applications of a vehicle, the device comprising a housing having a base and a cover, a radar unit mounted on a printed circuit board (PCB), and a shield covering the radar unit and configured to provide EMC (electromagnetic compatibility) shielding for the radar unit, wherein the shield is fixedly attached to an inner bottom of the base, and the base is provided with a support structure comprising a plurality of support elements configured to provide support for the PCB and / or the shield.

[0008] This radar device does not include a traditional heat sink. Instead, heat generated by the radar unit is dissipated externally through the housing, to which the shield is fixedly attached. Heat generated by the radar unit is absorbed by the shield and transferred to the base, which effectively dissipates the heat to the radar device's surroundings. By eliminating dedicated heat sink components, this radar device can be manufactured more cost-effectively than previous radar devices that included them. This reduction in the number of components reduces bill of materials (BOM) costs and shortens the assembly time of the radar device.

[0009] The base and cover can be rectangular in shape and form a flat housing for the radar device. The base includes a flat bottom surface and four side walls. One of the side walls can be provided with an organic electrical connector for connecting the radar device to, for example, a vehicle or a component thereof.

[0010] The base can include multiple compartments that can be separated from each other by support elements of the support structure. The support structure with multiple support elements can provide a stable hard stop for the PCB during assembly of the radar device. The support elements are formed of a stiff material and can include, for example, a bar, a bridge, a ridge, a pillar, and a platform.

[0011] The support element can extend from the inner bottom of the base and / or can extend from the inner surface of the side wall of the base. The support element can also be part of the base itself. For example, the support element can be a bridge portion that forms a partition wall between different compartments of the base. The support element can form a ridge that extends on the inner side wall of the base to provide support for the PCB and / or shield. The support element can also be a part of the side wall of the base that forms a horizontal platform for supporting the printed circuit board and / or shield.

[0012] Multiple support elements support the printed circuit board at various locations along its length, ensuring that the PCB is securely positioned and reliably retained within the radar device. Due to the enhanced rigidity of the base and its supporting structure, a heat sink is no longer required to provide stable support during press-fit assembly of the PCB. The robustness of the base and its supporting structure ensures problem-free assembly and flawless operation of the radar device.

[0013] Therefore, the radar device is cost-effective, easy to assemble and reliable in operation.

[0014] According to one embodiment of the first aspect, the shield is a stamped metal spring, in particular a stamped steel spring. Specifically, the shield is formed as a thin stamped metal spring. The metal spring has a rectangular shape and includes a flat bottom surface and four side walls. Adjacent side walls may not be connected to each other and may form edge openings extending along the four side edges. Alternatively, adjacent side walls may be connected by a plurality of connecting elements (e.g., flanges or tabs).

[0015] The flat bottom surface is fixedly attached to the inner bottom of the base, while the sidewalls extend from the flat bottom surface of the metal spring to the surface of the PCB. Support for the sidewalls of the metal spring is provided by support elements of the support structure. At least one sidewall is electrically connected to a ground path on the PCB.

[0016] The rectangular metal spring and the PCB form a cavity that protects the radar unit placed within it from electromagnetic interference (EMI) or radio frequency (RF) interference. Therefore, only components sensitive to EMI or RF interference can be placed on the PCB within the cavity formed by the shield. Other components not affected by the interference can be placed outside the shielded area on the PCB. This reduces the size of the shield and reduces costs.

[0017] Therefore, the primary purpose of the shield is to provide effective EMC shielding for the radar unit. Furthermore, the stamped metal springs compensate for manufacturing tolerances in the radar unit's housing and PCB components. Due to the shield's reduced thickness and volume, its thermal capacity is limited. Heat generated by the radar unit is absorbed by the shield and quickly dissipated to the base of the housing. Stamped metal springs are easy to manufacture and provide cost-effective EMC shielding for the radar unit.

[0018] According to one embodiment of the first aspect, the shielding member contacts the inner bottom of the base. Thus, a contact area is formed between the outer surface of the shielding member and the inner bottom of the base. Because the shielding member and the base are in direct contact with each other, heat is more efficiently dissipated from the shielding member to the base, and ultimately, to the exterior of the radar apparatus.

[0019] According to one embodiment of the first aspect, at least 70% of the outer surface of the shield on the opposite side of the PCB is in direct contact with the inner bottom of the base. Thus, a contact area is formed between the outer surface of the shield and the inner bottom of the base, which includes at least 70% of the outer surface of the shield on the opposite side of the PCB. Because the shield and the base are in direct contact with each other over a majority of the outer surface of the PCB, heat can be more efficiently dissipated from the shield to the base and ultimately to the exterior of the radar device. To improve the efficiency of the above-mentioned heat dissipation, the proportion of the contact area of the outer surface of the shield can also be greater than 70%, in particular 80%, 85%, or 90%.

[0020] The shield may also be provided with a circular opening formed in a flat bottom surface of the shield opposite the transmitting and receiving parts of the radar unit to further improve the dissipation of heat generated by the radar unit.

[0021] According to one embodiment of the first aspect, the shield is fixedly attached to the inner bottom of the base by a plurality of fastening means. The fastening means ensure that the shield and the base are firmly connected to each other. Specifically, the fastening means prevent the shield from being displaced relative to the inner bottom of the base.

[0022] According to one embodiment of the first aspect, the plurality of fastening devices are formed by a plurality of hot-driving joints. The hot-driving joints enable the shield to be attached to the base to be securely and easily achieved. The hot-driving joints can be formed by hot-driving plastic nails provided on the inner bottom of the base, wherein the plastic nails have been inserted into corresponding openings of the shield before hot-driving is performed. For a shield formed by a stamped metal spring, the opening is provided in the bottom surface of the metal spring. The plastic nails extend from the inner bottom of the base to a length that exceeds the thickness of the shield to be attached to the base. This allows hot-driving to be performed easily. After hot-driving, the plastic nails form button-shaped rivets that securely connect the base and the shield. The hot-driving joints can be arranged along the edge of the inner bottom of the base. At least one of the hot-driving joints can be arranged adjacent to the circular opening of the shield.

[0023] According to one embodiment of the first aspect, the housing is made of plastic. A housing made of plastic is easy and cost-effective to manufacture. It can provide the necessary rigidity to the base and its supporting structure, thereby providing a secure support and a secure hard stop for the PCB during press-fit assembly.

[0024] According to one embodiment of the first aspect, the housing is made of a thermally conductive plastic, particularly one having a thermal conductivity of at least 5 W / mK. The use of the thermally conductive plastic enhances the heat dissipation capability of the radar device. Thus, the housing made of the thermally conductive plastic enables the radar device to effectively dissipate heat and maintain reliable performance despite increased heat generation.

[0025] According to one embodiment of the first aspect, the base and support structure are formed as a single piece. This enhances the structural stability and rigidity of the support structure, ensuring secure support for the PCB. Forming the base and support structure as a single piece is highly cost-effective and helps further reduce the manufacturing cost of the radar device.

[0026] In a second aspect, the present disclosure relates to a method for manufacturing a radar device, the method comprising the steps of: providing a housing including a cover and a base, the base having a support structure including a plurality of support elements; inserting a shielding member into an interior of the base, the shielding member being configured to provide EMC (electromagnetic compatibility) shielding for a radar unit; fixedly attaching the shielding member to an inner bottom of the base; arranging a PCB including the radar unit on the support elements of the base, press-fitting the PCB; and attaching the cover to the base to close the housing.

[0027] Because this radar device lacks a heat sink, assembly time is shortened compared to previous radar devices equipped with such dedicated heat sink components. Consequently, by eliminating heat sink components, this radar device can be manufactured more cost-effectively than previous radar devices. This reduction in the number of components reduces bill of materials (BOM) costs and shortens the assembly time of the radar device.

[0028] During assembly of the radar device, a support structure comprising multiple support elements provides a secure, hard stop for the PCB. The support elements are made of a hard material and may include, for example, poles, bridges, ridges, struts, and platforms. The multiple support elements support the PCB at various locations along its extended portion, ensuring that the PCB is securely stopped and reliably retained within the radar device. Due to the enhanced rigidity of the base and its support structure, a heat sink is no longer required to provide secure support during press-fit assembly of the PCB. The robustness of the base and its support structure therefore ensures problem-free assembly and trouble-free operation of the radar device.

[0029] The method for producing a radar device therefore requires fewer components and enables a shorter assembly time, thereby ensuring a problem-free and cost-effective assembly of the radar device.

[0030] According to one embodiment of the second aspect, the shield is a stamped metal spring, in particular a stamped steel spring. Specifically, the shield is formed as a thin stamped metal spring. The primary purpose of the shield is to provide effective EMC shielding for the radar device. Furthermore, the stamped metal spring compensates for manufacturing tolerances in the housing and PCB components of the radar device. Due to the reduced thickness and volume of the shield, the shield has a limited thermal capacity. Heat generated by the radar unit is absorbed by the shield and quickly dissipated to the base of the housing. The stamped metal spring is easy to manufacture and provides cost-effective EMC shielding for the radar unit.

[0031] According to one embodiment of the second aspect, the housing is made of plastic, particularly thermally conductive plastic. Specifically, the housing is made of thermally conductive plastic with a thermal conductivity of at least 5 W / mK. Housings made of plastic are easy and cost-effective to manufacture. They provide the necessary rigidity to the base and its supporting structure, providing a secure support and a firm stop for the PCB during press-fit assembly. The use of thermally conductive plastic enhances the heat dissipation capability of the radar device. Consequently, a housing made of thermally conductive plastic enables the radar device to effectively dissipate heat and maintain reliable performance despite increased heat generation.

[0032] According to one embodiment of the second aspect, the shield is fixedly attached to the inner bottom of the base via a plurality of fastening devices. Specifically, the shield contacts the inner bottom of the base. This creates a contact area between the outer surface of the shield and the inner bottom of the base. Because the shield and base are in direct contact, heat can be more efficiently dissipated from the shield to the base and ultimately to the exterior of the radar device.

[0033] Therefore, at least 70% of the outer surface of the shield on the opposite side of the PCB can be in direct contact with the inner bottom of the base. Thus, a contact area can be formed between the outer surface of the shield and the inner bottom of the base, which includes at least 70% of the outer surface of the shield on the opposite side of the PCB. Because the shield and the base are in direct contact with each other over a large portion of the outer surface of the PCB, heat is more efficiently dissipated from the shield to the base and ultimately to the exterior of the radar device. To improve the efficiency of this heat dissipation, the proportion of the outer surface of the shield in contact can also be greater than 70%, in particular 80%, 85%, or 90%.

[0034] Furthermore, the shield may also be provided with a circular opening formed in a flat bottom surface of the shield opposite the transmitting and receiving parts of the radar unit to further improve the dissipation of heat generated by the radar unit.

[0035] According to one embodiment of the second aspect, the inner bottom of the base is provided with a plurality of plastic pegs, the shield is provided with a corresponding plurality of openings, and the shield is inserted into the interior of the base by inserting the corresponding plurality of plastic pegs into the plurality of openings. The plurality of pegs can extend from the inner bottom of the base and can be formed integrally with the base. The openings can be cost-effectively formed as holes during the formation of the shield. For shields formed from stamped metal springs, the openings are provided in the bottom surface of the metal spring.

[0036] According to one embodiment of the second aspect, after the shield is inserted into the interior of the base, the shield is fixedly attached to the inner bottom of the base by hot staking plastic nails. The plastic nails extend from the inner bottom of the base to a length that exceeds the thickness of the shield to be attached to the base. This allows hot staking to be easily performed. After hot staking, the plastic nails form button-shaped rivets that fixedly connect the base and the shield. The hot staking joints can be arranged along the edge of the inner bottom of the base. At least one of the hot staking joints can be arranged adjacent to the circular opening of the shield. After hot staking, the plastic nails form a stable fastening device for connecting the base and the shield.

[0037] The heat-staking joint enables secure and easy attachment of the shield to the base. However, the present disclosure is not limited to attachment via heat-staking joints, and other methods of fixedly attaching the shield to the base may be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Exemplary embodiments and functionality of the present disclosure are described herein in conjunction with the following figures, which schematically illustrate:

[0039] Figure 1 schematically shows a cross-sectional view of an embodiment of a radar device;

[0040] Figure 2 The translucent housing schematically illustrates the Figure 1 A perspective view of a radar installation;

[0041] Figure 3 Schematically shows Figure 1 Another perspective view of the radar device. DETAILED DESCRIPTION

[0042] Figure 1 A cross-sectional view of one embodiment of radar device 10 is depicted. Figure 2 and Figure 3 Depicts Figure 1 Two perspective views of an embodiment of the present invention, wherein Figure 2 The radar device 10 is shown through a translucent housing.

[0043] Radar device 10 includes a housing 12 having a base 14 and a cover 16 , a radar unit 18 mounted on a printed circuit board (PCB) 20 , and shielding 22 covering radar unit 18 and configured to provide EMC (electromagnetic compatibility) shielding for radar unit 22 .

[0044] Base 14 and cover 16 are rectangular in shape and form the flat housing 12 of radar device 10. Base 14 includes a flat bottom surface 14a and four side walls 14b. One of side walls 14b is provided with an electrical and mechanical connector 38 for connecting radar device 10 to, for example, a vehicle (not shown) or a component thereof. Base 14 includes a plurality of compartments 15a, 15b, which are separated from one another by support elements 30 of support structure 28.

[0045] The shield 22 is fixedly attached to the inner bottom 24 of the base 14 by a plurality of fastening means 26. The base 14 is provided with a support structure 28 comprising a plurality of support elements 30 configured to provide support to the PCB 20.

[0046] Shield 22 is a thin stamped metal spring (thin stamped metal spring, thin stamped metal spring plate, thin stamped metal leaf), specifically a thin stamped steel spring (thin stamped steel spring, thin stamped steel leaf). The metal spring has a rectangular shape and includes a flat bottom surface 22a and four side walls 22b. In this embodiment, adjacent side walls are not connected to each other and form edge openings 22c extending along the four side edges. Alternatively, adjacent side walls can also be connected by multiple connecting elements (e.g., flanges or tabs).

[0047] The flat bottom surface 22a is fixedly attached to the inside bottom 24 of the base 14, while the side walls 22b extend from the flat bottom surface 22a of the metal spring 22 to the surface of the PCB 20. Support for the side walls 22b of the shield 22 is provided by support elements 30 of the support structure 28. At least one of the side walls 22a is provided for electrical connection to a ground path on the PCB 20.

[0048] The rectangular metal spring 22 and the PCB 20 form a cavity 40 that protects the radar unit 18 disposed within the cavity 40 from electromagnetic interference (EMI) or radio frequency (RF) interference. Therefore, only components that are sensitive to EMI or RF interference are disposed on the PCB 20 within the cavity 40 formed by the shield 22. Other components that are not susceptible to such interference are disposed on the PCB 20 outside the shielded area.

[0049] The primary purpose of the shield 22 is to provide effective EMC shielding for the radar unit 18. In addition, the stamped metal springs 22 also provide compensation for manufacturing tolerances of the housing 12 and PCB 20 components of the radar device 10.

[0050] Shield 22 is in direct contact with inner bottom 24 of base 14. Consequently, a contact area 32 is formed between outer surface 34 of shield 22 and inner bottom 24 of base 14. Contact area 32 comprises at least 70% of outer surface 34 of shield 22 on the side opposite printed circuit board 20. This allows heat generated by radar unit 18 to be efficiently dissipated from shield 22 to base 14, and ultimately to the exterior of radar device 10. Furthermore, shield 22 is provided with a circular opening 42 formed in its flat bottom surface 22a, opposite the transmitting and receiving components of radar unit 18, to further improve the dissipation of heat generated by radar unit 18.

[0051] Housing 12 is made of plastic, particularly thermally conductive plastic. This plastic material provides the necessary rigidity to base 14 and its supporting structure 28. The use of thermally conductive plastic enhances the heat dissipation capabilities of radar device 10. Therefore, housing 12 made of thermally conductive plastic ensures effective heat dissipation and reliable performance even when heat generation increases.

[0052] The shield 22 is fixedly attached to the base 14 by a plurality of heat staked joints 26, which securely attach the shield 22 to the base 14. The heat staked joints 26 are formed by heat staking unillustrated plastic spikes provided on the inner bottom 24 of the base 14, wherein the plastic spikes have been inserted into corresponding openings 36 in the shield 22 prior to performing the heat staking.

[0053] Therefore, the plastic nail extends from the inner bottom 24 of the base 14 to a length that exceeds the thickness of the shield 22 to be attached to the base 14. This allows for easy hot staking. After hot staking, the plastic nail forms a button-shaped rivet 26 that securely connects the base 14 and the shield 22. The hot-staking joint 26 is arranged along the edge of the inner bottom 24 of the base 14. Another hot-staking joint 26 is arranged adjacent to the circular opening 42 of the shield 22.

[0054] Base 14 and support structure 28 are formed as one piece, which enhances the structural stability and rigidity of support structure 28 and ensures firm support for PCB 20. Support structure 28 includes a plurality of support elements 30, which may include, for example, posts, bridges 30a, spines, pillars, and platforms 30b.

[0055] The support member 30 may extend from the inner bottom 24 of the base 14 and / or from the inner surface of the sidewall 14b of the base 14. The support member 30 may also be part of the base 14 itself. The support member 30 includes at least one bridge portion 30a, which forms a partition wall between the compartments 15a and 15b of the base 14. The bridge portion 30a provides support for the PCB 20 and the shield 22. The support member 30 also includes a horizontal platform 30b, which is part of the sidewall 14b of the base 14 for supporting the PCB 20 and / or the shield 22.

[0056] A plurality of support elements 30 support the PCB 20 at various locations along its extension and ensure that the PCB 20 is securely retained and reliably held within the radar device 10. The support structure 28 and its support elements 30 provide a secure support for the PCB 20 and a secure hard stop for the PCB 20 during press-fit assembly.

[0057] During assembly of radar device 10, shield 22 is inserted into the interior of base 14 and fixedly attached to base 14 by heat staking as described above. Next, PCB 20 is placed on support elements 30 of base 14 and press-fit assembly is performed on the PCB. During press-fit, support structure 28 and its support elements 30 provide a secure hard stop for PCB 20. Following press-fit, cover 16 is attached to base 14 to enclose housing 12 and complete assembly of radar device 10.

[0058] Due to the enhanced rigidity of base 14 and its support structure 28, a heat sink is no longer required to provide stable support during press-fit assembly of PCB 20. Thus, the robustness of base 14 and its support structure 28 ensures problem-free assembly and trouble-free operation of radar device 10.

[0059] By eliminating the dedicated heat sink component, the radar device 10 can be manufactured more cost-effectively than previous radar devices that include a heat sink component. The reduction in the number of components reduces bill of materials (BOM) costs and enables the assembly time of the radar device 10 to be shortened.

[0060] The method for manufacturing the radar device 10 requires fewer parts and results in a shorter assembly time, thus ensuring that the radar device 10 can be assembled without problems and cost-effectively.

[0061] Reference Signs List

[0062] 10 Radar device

[0063] 12 Housing

[0064] 14 base

[0065] 14a Bottom surface of base

[0066] 14b Side wall of the base

[0067] Compartment 15a

[0068] Compartment 15b

[0069] 16 Lid

[0070] 18 radar units

[0071] 20PCB

[0072] 22 Shielding

[0073] 22a Bottom surface of shield

[0074] 22b Side wall of shield

[0075] 22c Edge opening of shield

[0076] 24 Inner bottom of the base

[0077] 26 Fastening device / hot pile joint

[0078] 28 Support structure

[0079] 30 Support elements

[0080] 30a Bridge

[0081] 30b platform

[0082] 32 contact area

[0083] 34 Outer surface of the shield

[0084] 36 Opening

[0085] 38 Electromechanical Connectors

[0086] 40 chambers

[0087] 42 round opening

Claims

1. A radar device (10), the radar device (10) being used for an autonomous driving (AD) application or an advanced driver assistance system (ADAS) application of a vehicle, the device comprising: a housing (12), said housing (12) comprising a base (14) and a cover (16), a radar unit (18) mounted on a printed circuit board (PCB) (20), and a shield (22) covering the radar unit (18) and configured to provide EMC (electromagnetic compatibility) shielding to the radar unit (18), in: The shield (22) is fixedly attached to the inner bottom (24) of the base (14), and The base (14) is provided with a support structure (28) comprising a plurality of support elements (30) configured to provide support to the printed circuit board (20) and / or the shield.

2. The radar device (10) according to claim 1, characterized in that The shielding element (22) is a stamped metal spring, in particular a stamped steel spring.

3. The radar device (10) according to claim 1 or 2, characterized in that The shield (22) contacts the inner bottom (24) of the base (14).

4. The radar device (10) according to claim 3, characterized in that At least 70% of the outer surface (34) of the shield (22) on the opposite side of the printed circuit board (20) is in direct contact with the inner bottom (24) of the base (14).

5. The radar device (10) according to any one of claims 1 to 4, characterized in that The shield (22) is fixedly attached to the inner bottom (24) of the base (14) by a plurality of fastening means (26).

6. The radar device (10) according to any one of claims 1 to 5, characterized in that The plurality of fastening means (26) are formed by a plurality of heat pile joints.

7. The radar device (10) according to any one of claims 1 to 5, characterized in that The housing (12) is made of plastic.

8. The radar device (10) according to claim 7, characterized in that The housing (12) is made of a thermally conductive plastic, in particular a thermally conductive plastic having a thermal conductivity of at least 5 W / mK.

9. The radar device (10) according to any one of claims 1 to 8, characterized in that The base (14) and the support structure (28) are formed as one piece.

10. A method for producing a radar device (10), in particular a radar device (10) according to any one of claims 1 to 9, comprising the following steps: - providing a housing (12) comprising a cover (16) and a base (14), the base (14) having a support structure (28) comprising a plurality of support elements (30), - inserting a shield (22) into the interior of the base (14), the shield (22) being configured to provide EMC (Electromagnetic Compatibility) shielding to the radar unit (18), - fixedly attaching the shield (22) to the inner bottom (24) of the base (14), - arranging a printed circuit board (20) comprising the radar unit (18) on the support element (30) of the base (14), - press-fit assembly of the printed circuit board (20), - Attaching the cover (16) to the base (14) to close the housing (12).

11. The method according to claim 10, characterized in that The shielding element (22) is a stamped metal spring, in particular a stamped steel spring.

12. The method according to claim 10 or 11, characterized in that The housing (12) is made of plastic, in particular of heat-conducting plastic.

13. The method according to any one of claims 10 to 12, characterized in that The shield (22) is fixedly attached to the inner bottom (24) of the base (14) by a plurality of fastening means (26).

14. The method according to any one of claims 10 to 14, characterized in that The inner bottom (24) of the base (14) is provided with a plurality of plastic nails, the shielding member (22) is provided with a corresponding plurality of openings (36), and the shielding member (22) is inserted into the interior of the base (14) by inserting the corresponding plurality of plastic nails into the plurality of openings (36).

15. The method according to claim 14, characterized in that After the shield (22) is inserted into the interior of the base (14), the shield (22) is fixedly attached to the inside bottom (24) of the base (14) by hot staking the plastic nails.

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