A full shielded PCB board against electromagnetic interference

Abstract

The utility model discloses a full shielding anti-electromagnetic interference's PCB board, including substrate, the circuit layer of being located on the substrate and the insulating protective layer of covering circuit layer, still include integrative full -encapsulated electromagnetic shielding shell, the full -encapsulated electromagnetic shielding shell is by top cover shielding layer, bottom cover shielding layer and side wall shielding layer constitutes. Full -encapsulated shielding shell forms the no -gap seal body through pressing and laser welding, eliminates traditional slit magnetic leakage problem, and high -efficient reflection external electromagnetic wave and blocks internal signal leakage, and the shielding efficiency is greatly promoted. Metallization via, can fast guide and discharge high low frequency interference current, adapts industrial control, communication and other multi -scene. Shielding layer surface electromagnetic loss microstructure can dissipate high frequency interference energy, and the isolated shielded via can reduce signal crosstalk, and guarantee high -speed signal transmission integrity.

Description

Technical Field

[0001] This utility model relates to the field of PCB board technology, specifically a fully shielded PCB board that resists electromagnetic interference. Background Technology

[0002] To meet the trend of miniaturization and high-frequency development in electronic devices, the electromagnetic interference (EMI) problem of PCB boards, as core load-bearing components, is becoming increasingly prominent, directly restricting equipment performance and reliability. Current PCB anti-interference solutions have significant limitations: most employ partial shielding or single-layer grounding structures. Partial shielding is prone to creating "electromagnetic leakage paths" due to assembly gaps, drastically reducing shielding effectiveness at high frequencies; single-layer grounding networks cannot completely dissipate interference current, and residual interference can easily lead to circuit instability. Simultaneously, signal transmission vias lack dedicated shielding designs, allowing external interference to easily couple to signal conductors, resulting in high-speed signal crosstalk and increased bit error rate. Utility Model Content

[0003] To overcome the shortcomings of existing technical solutions, this utility model provides a fully shielded PCB board that resists electromagnetic interference, which can effectively solve the problems mentioned in the background art.

[0004] The technical solution adopted by this utility model to solve its technical problem is: A fully shielded PCB board for electromagnetic interference protection includes a substrate, a circuit layer disposed on the substrate, and an insulating protective layer covering the circuit layer. It also includes an integrally formed fully enclosed electromagnetic shielding shell, wherein the fully enclosed electromagnetic shielding shell is composed of a top cover shielding layer, a bottom cover shielding layer, and side wall shielding layers. The top cover shielding layer and the bottom cover shielding layer are respectively pressed onto the upper and lower surfaces of the substrate through an insulating protective layer. The side wall shielding layer extends circumferentially along the substrate and is welded to the top cover shielding layer and the bottom cover shielding layer to form a continuous conductive seal. The substrate is embedded with a multi-level grounding network, which is electrically connected to the sidewall shielding layer through metallized vias penetrating the substrate, forming a three-dimensional grounding structure.

[0005] As a further description of the above technical solution, the edges of the top cover shielding layer and the bottom cover shielding layer are provided with stepped shielding flanges that bend toward the substrate side, and the inner side of the side wall shielding layer is provided with an insert groove that matches the shielding flanges, forming a double-sealed interface of physical locking and electrical connection through laser welding.

[0006] As a further description of the above technical solution, the sidewall shielding layer is formed by bending copper-nickel alloy strip, with a thickness of 0.1-0.3mm and a height greater than the substrate thickness by 0.5-1mm. After welding, it forms a grounding pad mounting surface protruding from the substrate surface.

[0007] As a further description of the above technical solution, the multi-level grounding network includes: The surface grounding grid is located on the circuit layer surface and connected to the top of the metallized via. The inner ground plane is parallel to the inside of the substrate and is interconnected with the surface ground grid and the sidewall shielding layer through metallized vias.

[0008] As a further description of the above technical solution, the metallized vias are arranged in an array in the edge region of the substrate, the spacing between the metallized vias is less than 1 / 20 of the wavelength of the highest suppression frequency, and the inner holes of the metallized vias are filled with a high permeability magnetic powder composite material.

[0009] As a further description of the above technical solution, the surfaces of the top cover shielding layer and the bottom cover shielding layer are provided with periodically distributed electromagnetic loss microstructures, which are cross-shaped slot arrays or circular resonant cavity arrays formed by etching.

[0010] As a further description of the above technical solution, an isolated shielding through-hole is provided in the signal transmission area, the through-hole comprising: Signal conductors penetrating the substrate and shielding shell; A cylindrical shielding sleeve covering the signal conductor, with its two ends welded to the top cover shielding layer and the bottom cover shielding layer, respectively. A ferrite absorbing layer is filled between the shielding sleeve and the signal conductor.

[0011] Compared with the prior art, the beneficial effects of this utility model are: The fully shielded electromagnetic interference-resistant PCB board of this utility model has at least one of the following beneficial effects during use: The fully enclosed shielding shell is formed into a gapless seal through pressing and laser welding, eliminating the magnetic leakage problem of traditional gaps. It efficiently reflects external electromagnetic waves and blocks internal signal leakage, significantly improving shielding effectiveness. A three-dimensional grounding network combined with metallized vias arranged in an edge array (with via spacing less than 1 / 20 of the wavelength of the highest suppression frequency, filled with high-permeability material) can quickly conduct high and low frequency interference currents, making it suitable for various scenarios such as industrial control and communications. The electromagnetic loss microstructure on the shielding layer surface dissipates high-frequency interference energy, and the isolated shielding vias (containing a ferrite absorbing layer) reduce signal crosstalk, ensuring the integrity of high-speed signal transmission. Furthermore, the copper-nickel alloy sidewalls balance lightweight design and shielding performance, and the convex design simplifies installation, making it suitable for high-precision equipment in medical, aerospace, and other fields. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of a fully shielded PCB board that resists electromagnetic interference according to this utility model; Figure 2 This is an exploded structural diagram of a fully shielded PCB board that resists electromagnetic interference according to this utility model. Figure 3 This is a schematic diagram of the side structure of the substrate of a fully shielded PCB board that resists electromagnetic interference according to this utility model. Figure 4 This is a partial cross-sectional structural diagram of a fully shielded PCB board that resists electromagnetic interference according to this utility model.

[0013] Numbering on the map: 1. Fully enclosed electromagnetic shielding shell; 101. Electromagnetic loss microstructure; 102. Continuous conductive seal; 103. Top cover shielding layer; 104. Bottom cover shielding layer; 105. Side wall shielding layer; 2. Substrate; 201. Circuit layer; 202. Multi-level grounding network; 203. Shielding flange; 204. Insulating protective layer; 205. Metallized via; 206. Grounding pad mounting surface; 3. Isolated shielding through-hole; 301. Signal conductor; 302. Ferrite absorbing layer; 303. Shielding sleeve. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] like Figure 1-4 As shown, this utility model provides a fully shielded PCB board for electromagnetic interference, including a substrate 2, a circuit layer 201 disposed on the substrate 2 and an insulating protective layer 204 covering the circuit layer 201, and also includes an integrally formed fully enclosed electromagnetic shielding shell 1, which is composed of a top cover shielding layer 103, a bottom cover shielding layer 104 and a side wall shielding layer 105.

[0016] This embodiment achieves full-band, all-round suppression of electromagnetic interference through a multi-layered anti-interference structure of "physical isolation, interference discharge, energy loss, and local protection". The fully enclosed electromagnetic shielding shell 1 constructs an electromagnetic isolation barrier. The fully enclosed electromagnetic shielding shell 1 is a continuous conductive sealed body 102 formed by a top cover shielding layer 103 (upper surface), a bottom cover shielding layer 104 (lower surface), and a side wall shielding layer 105 (circumferential direction), and achieves gapless encapsulation through pressing and welding.

[0017] The top cover shielding layer 103 and the bottom cover shielding layer 104 are respectively pressed onto the upper and lower surfaces of the substrate 2 through the insulating protective layer 204. The side wall shielding layer 105 extends circumferentially along the substrate 2 and is welded to the top cover shielding layer 103 and the bottom cover shielding layer 104 to form a continuous conductive sealing body 102.

[0018] The top / bottom cover is pressed against the upper and lower surfaces of the substrate 2 through the insulating protective layer 204 to ensure a tight fit with the substrate 2 and avoid the formation of "electromagnetic leakage channels" due to interlayer gaps.

[0019] The sidewalls extend circumferentially along the substrate and are laser-welded into the "embedded grooves" with the stepped shielding flanges 203 (edge-bent structures) of the top / bottom cover, forming a double-sealed interface of "physical locking + electrical connection." This design eliminates the "gap magnetic leakage" problem of traditional shielding shells (electromagnetic interference easily penetrates through gaps, especially at high frequencies), ensuring the "continuous conductivity" of the shielding shell, which meets the core requirements of electromagnetic shielding (conductivity continuity is key to shielding effectiveness). It also reflects externally incident electromagnetic waves (due to the high reflectivity of metallic materials) and blocks electromagnetic signals generated by internal circuits from leaking outward, preventing interference with surrounding equipment.

[0020] The substrate 2 is embedded with a multi-level grounding network 202. The grounding network is electrically connected to the sidewall shielding layer 105 through the metallized vias 205 penetrating the substrate 2, forming a three-dimensional grounding structure.

[0021] The surface grounding grid covers the surface of circuit layer 201, directly collecting interference current generated by the surface circuit. The inner grounding plane is parallel to the interior of substrate 2, collecting interference current from the inner circuit. The metallized via 205 acts as a "current discharge channel," conducting the interference current from the surface / inner layer to the sidewall shielding layer 105, and finally dissipating it through the shielding shell ground (implicit design, the shielding shell needs an external grounding terminal).

[0022] Furthermore, the edges of the top cover shielding layer 103 and the bottom cover shielding layer 104 are provided with stepped shielding flanges 203 that bend towards the substrate 2. The inner side of the side wall shielding layer 105 is provided with an insert groove that matches the shielding flange 203. A dual-sealed interface for physical locking and electrical connection is formed by laser welding. The side wall shielding layer 105 is formed by bending copper-nickel alloy strip, with a thickness of 0.1-0.3 mm and a height greater than the thickness of the substrate 2 by 0.5-1 mm. After welding, it forms a grounding pad mounting surface 206 protruding from the surface of the substrate 2.

[0023] The sidewall shielding layer 105 is made of copper-nickel alloy strip with a thickness of 0.1-0.3mm (balancing shielding effectiveness and lightweight), and a height greater than the substrate 2 by 0.5-1mm. After welding, it forms a "grounding pad mounting surface 206 protruding from the substrate 2" - which facilitates the grounding connection between the PCB and external equipment and simplifies the installation process.

[0024] Furthermore, the multi-level grounding network 202 includes: a surface grounding grid located on the surface of the circuit layer 201 and connected to the top of the metallized via 205; and an inner grounding plane disposed parallel to the interior of the substrate 2, interconnected with the surface grounding grid and the sidewall shielding layer 105 through the metallized via 205.

[0025] The multi-level grounding network 202 can overcome the limitation of traditional PCBs that "can only shield a single frequency band" and is suitable for various scenarios such as industrial control (low-frequency motor interference) and wireless communication (high-frequency radio frequency interference).

[0026] Furthermore, the metallized vias 205 are arranged in an array in the edge region of the substrate 2, the spacing between the metallized vias 205 is less than 1 / 20 of the wavelength of the highest suppression frequency, and the inner holes of the metallized vias 205 are filled with a high permeability magnetic powder composite material.

[0027] Metallized vias 205 “edge array arrangement”: the hole spacing is less than “1 / 20 of the wavelength of the highest suppression frequency” – according to the “hole shielding formula” of electromagnetic shielding, when the hole spacing is much smaller than the wavelength of electromagnetic waves, it can effectively suppress the propagation of electromagnetic waves through the hole array (equivalent to forming an “electromagnetic barrier”) and prevent interference from penetrating through the via gaps at the edge of the substrate 2.

[0028] Furthermore, the surfaces of the top cover shielding layer 103 and the bottom cover shielding layer 104 are provided with periodically distributed electromagnetic loss microstructures 101, which are etched cross-shaped slot arrays or circular resonant cavity arrays.

[0029] The top / bottom cover surfaces are etched with a "cross-shaped slot array" or a "circular resonant cavity array" (periodic microstructure), the size of which matches the target suppression frequency. Utilizing the principle of "electromagnetic resonance loss," when electromagnetic waves of a specific frequency (such as high-frequency interference) are incident on the microstructure, electromagnetic resonance is generated within the resonant cavity, converting the electromagnetic wave energy into heat energy (Joule heating) for dissipation, thus achieving targeted suppression of "specific high-frequency interference." This design can compensate for the problem of "insufficient high-frequency shielding effectiveness" in traditional shielding shells, and is especially suitable for scenarios such as communication and industrial control that require suppression of interference in specific frequency bands (such as GHz levels).

[0030] Furthermore, an isolation shielding through-hole 3 is provided in the signal transmission area, and this through-hole includes: A signal conductor 301 penetrates the substrate 2 and the shielding shell. A cylindrical shielding sleeve 303 covers the signal conductor 301, and the two ends of the shielding sleeve 303 are welded to the top cover shielding layer 103 and the bottom cover shielding layer 104, respectively. A ferrite absorbing layer 302 is filled between the shielding sleeve 303 and the signal conductor 301.

[0031] A cylindrical shielding sleeve 303 covers the signal conductor 301 and is welded to the top / bottom cover at both ends, forming a "partial shielding cover" for the signal conductor 301 to prevent external interference from coupling to the signal conductor 301. A ferrite absorbing layer 302 is filled between the shielding sleeve 303 and the signal conductor 301. The ferrite material can absorb residual high-frequency interference that penetrates the shielding sleeve 303 through "permeability loss", reducing the "crosstalk" of interference to the signal (such as inter-symbol interference in high-speed signal transmission).

[0032] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A fully shielded PCB board for electromagnetic interference suppression, comprising a substrate, a circuit layer disposed on the substrate, and an insulating protective layer covering the circuit layer, characterized in that, It also includes an integrally molded, fully enclosed electromagnetic shielding shell, which is composed of a top cover shielding layer, a bottom cover shielding layer, and side wall shielding layers; The top cover shielding layer and the bottom cover shielding layer are respectively pressed onto the upper and lower surfaces of the substrate through an insulating protective layer. The side wall shielding layer extends circumferentially along the substrate and is welded to the top cover shielding layer and the bottom cover shielding layer to form a continuous conductive seal. The substrate is embedded with a multi-level grounding network, which is electrically connected to the sidewall shielding layer through metallized vias penetrating the substrate, forming a three-dimensional grounding structure.

2. The fully shielded electromagnetic interference PCB board according to claim 1, characterized in that: The top cover shielding layer and the bottom cover shielding layer have stepped shielding flanges that bend toward the substrate side at their edges. The inner side of the side wall shielding layer has an insert groove that matches the shielding flange. A double-sealed interface for physical locking and electrical connection is formed by laser welding.

3. The fully shielded electromagnetic interference PCB board according to claim 2, characterized in that: The sidewall shielding layer is formed by bending copper-nickel alloy strip, with a thickness of 0.1-0.3mm and a height greater than the substrate thickness by 0.5-1mm. After welding, it forms a grounding pad mounting surface that protrudes from the substrate surface.

4. The fully shielded electromagnetic interference PCB board according to claim 1, characterized in that: The multi-level grounding network includes: The surface grounding grid is located on the circuit layer surface and connected to the top of the metallized via. The inner ground plane is parallel to the inside of the substrate and is interconnected with the surface ground grid and the sidewall shielding layer through metallized vias.

5. A fully shielded PCB board for electromagnetic interference protection according to claim 1 or 4, characterized in that: The metallized vias are arranged in an array at the edge region of the substrate. The spacing between the metallized vias is less than 1 / 20 of the wavelength of the highest suppression frequency. The inner holes of the metallized vias are filled with a high-permeability magnetic powder composite material.

6. The fully shielded electromagnetic interference PCB board according to claim 1, characterized in that: The surfaces of the top cover shielding layer and the bottom cover shielding layer are provided with periodically distributed electromagnetic loss microstructures, which are etched cross-shaped slot arrays or circular resonant cavity arrays.

7. A fully shielded PCB board for electromagnetic interference protection according to claim 1, characterized in that: An isolated shielding via is provided in the signal transmission area. This via includes: Signal conductors penetrating the substrate and shielding shell; A cylindrical shielding sleeve covering the signal conductor, with its two ends welded to the top cover shielding layer and the bottom cover shielding layer, respectively. A ferrite absorbing layer is filled between the shielding sleeve and the signal conductor.

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