Miniaturized multilayer electromagnetic bandgap structure

Abstract

The application discloses a miniaturized multilayer electromagnetic bandgap structure. A dielectric substrate is arranged on a common ground plate, and three layers of metal structures, namely a first layer of spiral structure metal patch, a second layer of Z-shaped structure metal patch and a third layer of inverted Z-shaped structure metal patch, are sequentially embedded in the dielectric substrate from top to bottom. The first layer of spiral structure metal patch and the second layer of Z-shaped structure metal patch, the second layer of Z-shaped structure metal patch and the third layer of inverted Z-shaped structure metal patch, and the third layer of inverted Z-shaped structure metal patch and the common ground plate are electrically connected through metal through holes. The electromagnetic bandgap structure works at a lower frequency, can reduce electromagnetic radiation leakage between sputtering film and a PCB ground plane, and improves electromagnetic shielding effectiveness of a system-in-package.

Description

Technical Field

[0001] This invention relates to an electromagnetic bandgap shielding structure in the field of electromagnetic radiation technology, and more particularly to a miniaturized multilayer electromagnetic bandgap structure for suppressing electromagnetic radiation leakage in system-level packaging. Background Technology

[0002] System-in-package (SiP) integrates multiple different functional units within a single package, characterized by high integration, high speed, and multifunctionality, playing a crucial role in making electronic devices more portable and integrating more functions. However, with the increase in circuit density and operating frequency within SiP, electromagnetic interference (EMI) problems often arise. To suppress electromagnetic radiation from within the package, shielding covers or other structures are typically used as electromagnetic shielding solutions. Traditional metal shielding covers, due to their specific structure, usually occupy a large area and height. Therefore, conformal shielding, which adds almost no extra space to the SiP and has good shielding effectiveness, has received widespread attention, and SiP based on conformal shielding is being increasingly studied by researchers.

[0003] However, conformal shielding technology, as an electromagnetic shielding solution for system-in-package (SiP), is not yet mature and can cause electromagnetic radiation leakage outside the package, resulting in electromagnetic interference to adjacent devices. Therefore, effectively suppressing electromagnetic radiation leakage in SiP using conformal shielding is crucial for the development of the chip packaging field. Summary of the Invention

[0004] To reduce radiation leakage in existing conformal shielding-based system-in-package electromagnetic shielding solutions, especially at the junction of the coating and the PCB ground plane, this invention provides a miniaturized multilayer electromagnetic bandgap structure, which is positioned inside the circuit board (16) beneath the package substrate (12). This structure utilizes the working principle of a distributed parallel LC network with a specific resonant frequency, equivalent to an electromagnetic bandgap structure, to suppress electromagnetic radiation leakage within a specific frequency band.

[0005] In view of the above problems, the present invention proposes the following technical solution:

[0006] I. A miniaturized multilayer electromagnetic bandgap structure:

[0007] The electromagnetic bandgap structure includes a first layer of spiral metal patch, a second layer of Z-shaped metal patch, a third layer of inverted Z-shaped metal patch, metal vias, a dielectric substrate, and a common ground plane. The dielectric substrate is disposed on the common ground plane. The dielectric substrate contains three layers of metal structure, namely the first layer of spiral metal patch, the second layer of Z-shaped metal patch, and the third layer of inverted Z-shaped metal patch, which are embedded from top to bottom. The first layer of spiral metal patch and the second layer of Z-shaped metal patch are electrically connected to each other, the second layer of Z-shaped metal patch and the third layer of inverted Z-shaped metal patch are connected to each other, and the third layer of inverted Z-shaped metal patch and the common ground plane are connected to each other through metal vias.

[0008] The first layer of metal patch has a rectangular metal plane at its center. A microstrip line is led out from each of the two diagonal corners of the rectangular metal plane. Both microstrip lines extend counterclockwise around the rectangular metal plane from their respective corners to the outer side of the diagonal. The second layer of Z-shaped metal patch and the third layer of inverted Z-shaped metal patch are single microstrip lines with Z-shaped bends. The two ends of the Z-shape of the second layer of Z-shaped metal patch and the third layer of inverted Z-shaped metal patch are located below the two diagonal corners of the microstrip lines connected to the rectangular metal plane. One of the two microstrip lines is electrically connected to one end of the second layer of Z-shaped metal patch via a first metal via and one end of the second layer of Z-shaped metal patch via a second metal via and one end of the third layer of inverted Z-shaped metal patch via a third metal via and a common ground plane.

[0009] One end of the microstrip line is connected to the corner of the rectangular metal plane, and the other end extends to the opposite corner of the rectangular metal plane but is not connected to the opposite corner of the rectangular metal plane.

[0010] The third layer of inverted Z-shaped metal patch is obtained by rotating the second layer of Z-shaped metal patch 180 degrees along the diagonal of the rectangular metal plane.

[0011] The straight metal segments in the middle of the second-layer Z-shaped metal patch and the straight metal segments in the middle of the third-layer inverted Z-shaped metal patch are arranged perpendicularly.

[0012] The first layer of spiral structure metal patch, the second layer of Z-shaped structure metal patch, and the third layer of inverted Z-shaped structure metal patch are copper material patches.

[0013] II. Applications of miniaturized multilayer electromagnetic bandgap structures:

[0014] It is used in system-in-package (SIP) to improve electromagnetic shielding effectiveness and for packaging high-frequency chips.

[0015] Multiple electromagnetic bandgap structures are arranged in an array along the plane of the circuit board inside the circuit board.

[0016] Multiple electromagnetic bandgap structures share the same common ground plane.

[0017] The dielectric substrate has a spiral metal patch with an electromagnetic bandgap structure printed on top, and a common ground plane below. The circuit board is a printed circuit board, and the common ground plane is the ground plane of the printed circuit board.

[0018] The common ground plane is printed on the back of the dielectric substrate, located on the bottom layer of the circuit board, and provides a common ground plane for the structure.

[0019] Multiple electromagnetic bandgap structures are applied inside the circuit board. A system-level packaging structure based on conformal shielding is set on the surface of the circuit board. The system-level packaging structure includes a coating, a packaging substrate, and a molding compound. The packaging substrate is located above the multiple electromagnetic bandgap structures arranged in an array. The packaging substrate is electrically connected to the ground plane of the circuit board through a grounding solder ball. Molding compound is set on both the top and bottom of the packaging substrate. The packaging substrate and the molding compound are surrounded by a coating. The packaging substrate is electrically connected to the coating.

[0020] The electromagnetic bandgap structures are periodically arranged according to their structural dimensions below the packaging substrate and inside the circuit board, and are connected to a common ground plane, such as... Figure 2 As shown.

[0021] The beneficial effects of this invention are:

[0022] Compared with existing technologies, the advantages of this invention are: the electromagnetic bandgap structure provided by this invention has a compact structure, achieving a low-profile miniaturized design, with the overall size of the 3*3 bandgap units being less than one-tenth of a wavelength. The bandgap unit structure of this invention is simple and easy to manufacture.

[0023] Compared to traditional electromagnetic bandgap structures, the proposed electromagnetic bandgap structure exhibits superior bandgap characteristics at low frequencies due to the effective increase in the equivalent inductance of the periodic units caused by the multi-layer structure connected by metal vias. This significantly improves electromagnetic field shielding effectiveness. This invention has significant application value in high-density, miniaturized designs such as system-in-package (SISP). Attached Figure Description

[0024] Figure 1 is a schematic diagram of the front view and top view of a miniaturized multilayer electromagnetic bandgap structure according to a specific embodiment of the present invention. Figure 1 (a) is a schematic diagram of the overall side view of the bandgap element. Figure 1 (b) is a top view of the first layer of spiral structure metal patch. Figure 1 (c) is a top view of the second layer of Z-shaped metal patch. Figure 1 (d) is a top view of the third layer of inverted Z-shaped metal patch.

[0025] Figure 2 This is a cross-sectional schematic diagram of the miniaturized multilayer electromagnetic bandgap structure proposed in this invention applied to system-in-package from the front view direction.

[0026] Figure 3 is a graph showing the relationship between the S21 parameter and the signal frequency of the miniaturized multilayer electromagnetic bandgap structure according to a specific embodiment of the present invention.

[0027] Figure 4 This is a comparison chart of the simulation results of magnetic field isolation for specific embodiments of the present invention using and not using miniaturized multilayer bandgap structures as system-level packaging electromagnetic shielding schemes.

[0028] In the figure: electromagnetic bandgap structure (1), first layer spiral structure metal patch (2), second layer Z-shaped structure metal patch (3), third layer inverted Z-shaped structure metal patch (4), metal through hole (5), dielectric substrate (6), common ground plane (7), rectangular metal plane (8), microstrip line (9), microstrip line (10), coating (11), packaging substrate (12), grounding solder ball (13), molding compound (14), radiation source (15), circuit board (16). Detailed Implementation

[0029] The invention will be further described below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the electromagnetic bandgap structure 1 includes a first layer of spiral metal patch 2, a second layer of Z-shaped metal patch 3, a third layer of inverted Z-shaped metal patch 4, a metal via 5, a dielectric substrate 6, and a common ground plane 7. The dielectric substrate 6 is arranged on the common ground plane 7. The dielectric substrate 6 has three layers of metal structure embedded from top to bottom: the first layer of spiral metal patch 2, the second layer of Z-shaped metal patch 3, and the third layer of inverted Z-shaped metal patch 4. The first layer of spiral metal patch 2, the second layer of Z-shaped metal patch 3, and the third layer of inverted Z-shaped metal patch 4 are arranged in parallel and spaced apart. The first layer of spiral metal patch 2 and the second layer of Z-shaped metal patch 3, the second layer of Z-shaped metal patch 3 and the third layer of inverted Z-shaped metal patch 4, and the third layer of inverted Z-shaped metal patch 4 and the common ground plane 7 are all electrically connected through the metal via 5.

[0031] In specific implementation, the electromagnetic bandgap structure has three layers of metal patches. The first layer, metal patch 2, has a rectangular metal plane 8 at its center. A microstrip line 9 is drawn from one corner of the rectangular plane, and the microstrip line 9 rotates counterclockwise around the central rectangular plane to the outer side of the opposite corner, but does not connect with the opposite corner of the rectangular metal plane 8. A microstrip line 10 is drawn from the other corner of the rectangular metal plane 8, and the microstrip line 10 rotates counterclockwise around the central rectangular plane to the outer side of the opposite corner, but does not connect with the opposite corner of the rectangular metal plane 8. The second layer, metal patch 3, is a single curved microstrip line structure, forming a Z-shape from the lower left corner to the upper right corner of the bandgap structure. The third layer, metal patch 4, is a curved microstrip line structure, running from the lower left corner of the first layer, metal patch 2, along an inverted Z-shaped path to the upper right corner. Metal patch 4 can be obtained by rotating metal patch 3 diagonally by 180 degrees. In the first layer of spiral structure metal patch 2, the end of the microstrip line 9 is electrically connected to one end of the second layer of Z-structure metal patch 3, the other end of the second layer of Z-structure metal patch 3 is connected to one end of the third layer of inverted Z-structure metal patch 4, and the other end of the third layer of inverted Z-structure metal patch 4 is connected to the common ground plane 7 through metal through holes 5.

[0032] Metal through holes 5 are provided between the first layer spiral structure metal patch 2, the second layer Z-shaped structure metal patch 3, and the third layer inverted Z-shaped structure metal patch 4. The third layer inverted Z-shaped structure metal patch 4 is connected to the common ground plate 7 through the metal through holes 5.

[0033] The three-layer metal patch of the electromagnetic bandgap structure is made of copper, and the metal via 5 is a copper pillar with a diameter of 0.0508 mm. The metal via 5 connects the three layers of the electromagnetic bandgap structure sequentially and electrically connects the third layer to the common ground plane 7. The metal vias 5 are all located at the ends of the microstrip lines in the three-layer metal bandgap structure to increase the current path.

[0034] The electromagnetic bandgap structure 1 is located inside the PCB structure below the packaging substrate 12. The electromagnetic bandgap structure has three layers of metal structure, which are arranged from near to far from the packaging substrate 12 as follows: the first layer is a spiral structure metal patch 2, the second layer is a Z-shaped structure metal patch 3, and the third layer is an inverted Z-shaped structure metal patch 4.

[0035] The center of the first layer of metal patch 2 is a rectangular metal plane 8. At the two diagonal corners of the rectangular metal plane 8, a microstrip line 9 and a microstrip line 10 are drawn out. The two microstrip lines 9 and 10 are both drawn from their own corners of the rectangular metal plane 8 in a counterclockwise direction around the rectangular metal plane 8 to the outside of the diagonal corner, that is, to the outside of the corner of the rectangular metal plane 8 connected by another microstrip line 9 that is not itself. The two microstrip lines 9 and 10 are both L-shaped.

[0036] Microstrip lines 9 and 10 are connected at one corner to the rectangular metal plane 8, and the other end extends to the outside of the opposite corner of the rectangular metal plane 8, but is not connected to the opposite corner of the rectangular metal plane 8.

[0037] In specific implementation, the two microstrip lines 9 and 10 are divided into a first microstrip line 9 and a second microstrip line 10. The first microstrip line 9 and the second microstrip line 10 are not directly connected. The first microstrip line 9 is led out from one corner of the rectangular metal plane 8 and runs counterclockwise around the rectangular metal plane 8 to the outside of the opposite corner. The second microstrip line 10 is led out from the opposite corner of the rectangular metal plane 8 and runs counterclockwise around the rectangular metal plane 8 to the outside of the opposite corner.

[0038] The second-layer Z-shaped metal patch 3 and the third-layer inverted Z-shaped metal patch 4 are single microstrip lines with Z-shaped bends. The corners of the Z-shape are all right angles. The two ends of the Z-shape of the second-layer Z-shaped metal patch 3 and the third-layer inverted Z-shaped metal patch 4 are located below the two opposite corners of the microstrip lines 9 and 10 connected on the rectangular metal plane 8, respectively.

[0039] Specifically, such as Figure 1 As shown, the second Z-shaped metal patch 3 extends from the lower left corner to the upper right corner of the first metal patch 2 in a Z-shape, that is, it extends in a Z-shape from below the lower left corner of the first microstrip line 9 to below the upper right corner of the second microstrip line 10; the third inverted Z-shaped metal patch 4 extends from the lower left corner of the first metal patch 2 to the upper right corner along an inverted Z-shaped route, that is, it extends in a Z-shape from below the upper right corner of the second microstrip line 10 to below the lower left corner of the first microstrip line 9.

[0040] One of the two microstrip lines 9 and 10 is electrically connected at one end, which extends to the outer side of the opposite corner of the rectangular metal plane 8, via the first metal via 5 and one end of the second Z-shaped metal patch 3. The other end of the second Z-shaped metal patch 3 is electrically connected via the second metal via 5 and one end of the third inverted Z-shaped metal patch 4. The other end of the third inverted Z-shaped metal patch 4 is electrically connected via the third metal via 5 and the common ground plane 7.

[0041] All metal vias are through holes. The presence of the second and third metal patches and metal vias can extend the current path, allowing the electromagnetic bandgap structure to operate at a lower frequency.

[0042] Electromagnetic bandgap structure 1 as shown Figure 1 (a) shows a schematic diagram of the side view, with the first layer of spiral structure metal patch 2 as shown. Figure 1 (b) shows a top-view schematic diagram, with the second layer of Z-shaped metal patch 3 as shown. Figure 1(c) shows a top-view schematic diagram, with the third layer of inverted Z-shaped metal patch 4 as shown. Figure 1 (d) shows a top-view schematic diagram. The gray circular holes in the diagram represent the positions of the metal vias 5 between the layers. By bending the microstrip lines and using a multilayer structure to effectively increase the equivalent inductance of the periodic cells, the electromagnetic bandgap structure exhibits good bandgap characteristics at low frequencies.

[0043] By setting an electromagnetic bandgap structure 1 inside the circuit board 16 below the packaging substrate 12, electromagnetic radiation leakage between the sputtered coating and the PCB ground plane is reduced, thereby improving the electromagnetic shielding effectiveness of the system-in-package.

[0044] The third layer of inverted Z-shaped metal patch 4 can be obtained by rotating the second layer of Z-shaped metal patch 3 diagonally by 180 degrees. Preferably, the metal straight line segment in the middle of the second layer of Z-shaped metal patch 3 and the metal straight line segment in the middle of the third layer of inverted Z-shaped metal patch 4 are arranged perpendicularly.

[0045] Metal through-hole 5 is a copper pillar with a diameter of 0.0508 mm.

[0046] The schematic diagram of the placement of the electromagnetic bandgap structure in the system-in-package (SIPP) from the front view is shown below. Figure 2 As shown, in practical applications of system-in-package (SIP) systems, the radiation source is generated by the current flowing from the signal solder balls of the BGA to the metal structure inside the package substrate.

[0047] Multiple electromagnetic bandgap structures are arranged in an array along the plane of the circuit board 16 inside the circuit board 16. The circuit board 16 can be a PCB, and the multiple electromagnetic bandgap structures share the same common ground plane 7.

[0048] Multiple electromagnetic bandgap structures are disposed inside the circuit board 16. A system-in-package (SIP) structure based on conformal shielding is disposed on the surface of the circuit board 16. The SIP structure includes a coating 11, a packaging substrate 12, and a molding compound 14. The packaging substrate 12 is located above the multiple electromagnetic bandgap structures arranged in an array. The packaging substrate 12 is connected to the circuit board 16 through grounding solder balls 13. Molding compound 14 is disposed on both the top and bottom of the packaging substrate 12. The packaging substrate 12 and the molding compound 14 are surrounded by the coating 11. The packaging substrate 12 is electrically connected to the coating 11. Chips and electronic devices can be embedded in the packaging substrate 12 and the molding compound 14 on the packaging substrate 12.

[0049] In this way, the electromagnetic bandgap structure is periodically arranged below the packaging substrate 12 and inside the circuit substrate 16 according to the unit size, and connected to the common ground plane 7.

[0050] The molding compound has a relative permittivity of 3.8 and a relative permeability of 1. The function of the molding compound 14 is to provide insulation, fix the device, and protect it from dust.

[0051] In a specific implementation, a radiation source 15 is arranged inside the packaging substrate 12 to simulate electromagnetic radiation emitted by electronic devices or chips. The radiation source 15 is located in the structure of the packaging substrate 12 and is an irregular metal structure.

[0052] The design principle of this invention is as follows:

[0053] In a system-in-package (SIP) system, the coating 11, the package substrate 12, the grounding solder ball 13, and the circuit board 16 can approximately form a shielding cavity, providing electromagnetic shielding. However, due to the need for surface traces on the PCB ground plane, openings exist between the coating and the PCB ground plane in the formed shielding cavity, which can lead to serious electromagnetic radiation leakage problems.

[0054] Generally, electromagnetic shielding can be studied by addressing the three elements of electromagnetic radiation: the radiation source, the propagation path, and the sensitive device. For the electromagnetic radiation problem of the system-in-package (SiP) encountered in this paper, electromagnetic shielding design can be approached from the propagation path. As mentioned above, the radiation source 15 is located within the package substrate 12 structure, and there is a gap between the coating and the PCB ground plane in the SiP. Therefore, a miniaturized multilayer electromagnetic bandgap structure can be placed inside the circuit board 16 below the package substrate 12 to provide electromagnetic shielding along the electromagnetic radiation leakage propagation path. Since the electromagnetic bandgap structure has a specific resonant frequency, the resonant frequency can be changed by designing the bandgap unit structure. Then, by utilizing the characteristic of infinite reactance at unit resonance, the propagation of electromagnetic waves near the resonant frequency can be blocked, thereby reducing electromagnetic radiation leakage.

[0055] like Figure 2 The diagram shown is a cross-sectional view of the miniaturized multilayer electromagnetic bandgap structure applied to a system-in-package (SiP) according to a specific embodiment of the present invention. The electromagnetic bandgap structure has a periodic dimension of 1.5mm * 1.5mm * 0.296mm and is positioned within the solder balls of the SiP. The radiation source 15 is located... Figure 2 The packaging substrate 12 shown is internally structured. An excitation source supplies current to the irregular metal structure inside the packaging substrate 12, thereby generating radiation. Electromagnetic bandgap structures are located on a plane below the packaging substrate 12 and inside the circuit substrate 16, with a total of 3*3 bandgap unit structures arranged, such as... Figure 2 As shown, the three-layer metal patch of the bandgap unit is connected to the common ground plane through metal through holes 5. In each bandgap unit, the first layer is connected to the second layer through the through hole in the lower left corner, the second layer is connected to the third layer through the through hole in the upper right corner, and the third layer is connected to the common ground plane 7 through the through hole in the lower left corner.

[0056] like Figure 3 The diagram shown illustrates the relationship between the S21 parameter and signal frequency of a miniaturized multilayer electromagnetic bandgap structure according to a specific embodiment of the present invention. When measuring the S21 parameter, 3*3 [unclear text - possibly referring to a specific configuration or feature] are first set on the dielectric substrate. Figure 1The electromagnetic bandgap structure is shown, and the proposed electromagnetic bandgap structure is connected to a common ground plane. A microstrip line, electrically connected to the ground plane on both sides via an excitation source and a resistor respectively, is suspended above the bandgap structure. This forms a "sandwich" structure by placing the two-dimensional electromagnetic bandgap material between the microstrip line and the common ground plane. The bandgap characteristics of the electromagnetic bandgap structure are measured using the suspended microstrip line method. As shown in the figure, the proposed electromagnetic bandgap structure exhibits a transmission stopband of less than -10 dB in the 4.94 GHz to 5.39 GHz frequency range.

[0057] like Figure 4 The figure shows a comparison of the simulation results of magnetic field isolation when using a miniaturized multilayer bandgap structure as the electromagnetic shielding solution for a system-in-package (SiP) according to a specific embodiment of the present invention. The comparison shows the near-field magnetic field isolation between not using the electromagnetic bandgap structure and having the bandgap structure placed in the circuit board 16 of the SiP. The simulated magnetic field isolation is equal to the maximum magnetic field value inside the package minus the maximum magnetic field value on the planes 1 mm above and around the coating. The minimum isolation on the five planes is then calculated. Comparing the bandgap characteristic measurements of the electromagnetic bandgap structure using a suspended microstrip line with the measurements taken within the SiP, a deviation in the bandgap center frequency can be observed. This is because the SiP contains a relatively complex structure and irregular radiation sources, resulting in a difference in the stopband frequency range. Statistically, when using the present invention as the electromagnetic shielding solution in the SiP, the isolation is improved by a maximum of approximately 4.6 dB, and the overall electromagnetic shielding performance of the package is not degraded within the target frequency band of 2 GHz to 8 GHz.

[0058] Simulation results show that the miniaturized multilayer electromagnetic bandgap structure proposed in this invention, after selecting appropriate size and materials, can improve the magnetic field isolation at relevant frequencies when applied in system-level packaging.

[0059] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection scope. Those skilled in the art will understand that various modifications and improvements can be made without departing from the scope and spirit disclosed in the appended claims, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A miniaturized multilayer electromagnetic bandgap structure, characterized in that: The electromagnetic bandgap structure (1) includes a first layer of spiral metal patch (2), a second layer of Z-shaped metal patch (3), a third layer of inverted Z-shaped metal patch (4), a metal through hole (5), a dielectric substrate (6), and a common ground plane (7); the dielectric substrate (6) is arranged on the common ground plane (7), and the dielectric substrate (6) is embedded with a three-layer metal structure consisting of a first layer of spiral metal patch (2), a second layer of Z-shaped metal patch (3), and a third layer of inverted Z-shaped metal patch (4) from top to bottom. The first layer of spiral metal patch (2) and the second layer of Z-shaped metal patch (3), the second layer of Z-shaped metal patch (3) and the third layer of inverted Z-shaped metal patch (4), and the third layer of inverted Z-shaped metal patch (4) and the common ground plane (7) are all electrically connected through the metal through hole (5); The first layer of spiral structure metal patch (2) has a rectangular metal plane (8) at its center. A microstrip line (9, 10) is drawn out from each of the two diagonal corners of the rectangular metal plane (8). The two microstrip lines (9, 10) are both drawn from their own corners of the rectangular metal plane (8) in a counterclockwise direction around the rectangular metal plane (8) to the outer side of the diagonal. The second layer of Z-shaped structure metal patch (3) and the third layer of inverted Z-shaped structure metal patch (4) are single microstrip lines with Z-shaped bends. The two ends of the Z-shape of the second layer of Z-shaped structure metal patch (3) and the third layer of inverted Z-shaped structure metal patch (4) are respectively located at... Below the two opposite corners of the microstrip lines (9, 10) connected on the rectangular metal plane (8); one of the two microstrip lines (9, 10) is electrically connected at one end extending to the outside of the opposite corner of the rectangular metal plane (8) via the first metal via (5) and one end of the second Z-shaped metal patch (3), the other end of the second Z-shaped metal patch (3) is electrically connected via the second metal via (5) and one end of the third inverted Z-shaped metal patch (4), and the other end of the third inverted Z-shaped metal patch (4) is electrically connected via the third metal via (5) and the common ground plane (7).

2. The miniaturized multilayer electromagnetic bandgap structure according to claim 1, characterized in that: One end of the microstrip line (9, 10) is connected to the corner of the rectangular metal plane (8), and the other end extends to the opposite corner of the rectangular metal plane (8) but is not connected to the opposite corner of the rectangular metal plane (8).

3. The miniaturized multilayer electromagnetic bandgap structure according to claim 1, characterized in that: The third inverted Z-shaped metal patch (4) is obtained by rotating the second Z-shaped metal patch (3) by 180 degrees along the diagonal of the rectangular metal plane (8).

4. The miniaturized multilayer electromagnetic bandgap structure according to claim 1, characterized in that: The metal straight line segment in the middle of the second-layer Z-shaped metal patch (3) and the metal straight line segment in the middle of the third-layer inverted Z-shaped metal patch (4) are arranged perpendicularly.

5. The miniaturized multilayer electromagnetic bandgap structure according to claim 1, characterized in that: The first layer of spiral structure metal patch (2), the second layer of Z-shaped structure metal patch (3), and the third layer of inverted Z-shaped structure metal patch (4) are copper material patches.

6. The application of the miniaturized multilayer electromagnetic bandgap structure according to any one of claims 1-5, characterized in that: It is used in system-in-package (SIP) to improve electromagnetic shielding effectiveness and for packaging high-frequency chips.

7. The application of the miniaturized multilayer electromagnetic bandgap structure according to claim 6, characterized in that: Multiple electromagnetic bandgap structures are arranged in an array along the plane of the circuit board (16) inside the circuit board (16).

8. The application of the miniaturized multilayer electromagnetic bandgap structure according to claim 6, characterized in that: Multiple electromagnetic bandgap structures share the same common ground plane (7).

9. The application of the miniaturized multilayer electromagnetic bandgap structure according to claim 6, characterized in that: Multiple electromagnetic bandgap structures are applied inside the circuit board (16). A system-level package structure based on conformal shielding is provided on the surface of the circuit board (16). The system-level package structure includes a coating (11), a package substrate (12), and a molding compound (14). The package substrate (12) is located above the multiple electromagnetic bandgap structures arranged in an array. The package substrate (12) is electrically connected to the ground plane of the circuit board (16) through a grounding solder ball (13). Molding compound (14) is provided on both the top and bottom of the package substrate (12). The package substrate (12) and the molding compound (14) are surrounded by a coating (11). The package substrate (12) is electrically connected to the coating (11).

Images