Chip electromagnetic protection shielding diaphragm based on magnetic conductivity single negative metamaterial

Abstract

The invention relates to the technical field of chip electromagnetic shielding, in particular to a magnetic conductivity single negative metamaterial-based chip electromagnetic protection shielding diaphragm, which is provided with three FR-4 dielectric layers, pp materials are added between the adjacent FR-4 dielectric layers, a plurality of groups of split resonant rings with gradually-changed widths are arranged in the FR-4 dielectric layers, each group of split resonant rings comprises three resonant single rings, and the resonant single rings are arranged in the middle of the FR-4 dielectric layers. The three resonant single rings are sequentially arranged according to the width and are embedded with resistors, and metal strips are added among the resonant single rings. Compared with a traditional electromagnetic shielding structure such as an electromagnetic band gap structure and a shielding-like material shielding structure, the shielding diaphragm structure has the advantages of being low in profile, small in transverse size and wide in working frequency band, is suitable for miniaturized chip structure protection, and can effectively solve the problem of electromagnetic interference generated in small compartment packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of chip electromagnetic shielding, and in particular to a chip electromagnetic protection shielding diaphragm based on magnetic permeability single negative metamaterial. Background Art

[0002] At present, information technology is developing rapidly and has become a key factor in promoting social development and human progress. Microelectronics technology represented by integrated circuit chips not only plays a key role in the development of the information society, but also plays a vital role in cutting-edge technology fields such as 5G communications and artificial intelligence, and emerging application fields such as unmanned driving and the Internet of Things. At present, many high-tech enterprises in my country are facing the problem of foreign supply of chip-related products, and the importance and urgency of conducting scientific research and technological innovation related to integrated circuits are more prominent.

[0003] On the one hand, the more closely packed circuits and higher operating frequencies make it easier for the internally generated electromagnetic noise to affect each other; on the other hand, the electromagnetic radiation in the external environment may also penetrate the packaging barrier and affect the normal operation of the equipment. Therefore, how to ensure that the integrated microelectronic system will neither generate interference nor be interfered with in a complex electromagnetic environment has become an urgent problem to be solved. In order to meet this challenge, researchers are exploring various solutions, such as improving shielding design, optimizing wiring strategies, adopting advanced filtering technology, and strengthening grounding measures. At the same time, permeability single negative metamaterials, that is, those artificial synthetic materials that can exhibit negative permeability within a specific frequency range, have attracted widespread attention from academia and industry due to their unique electromagnetic properties. At the same time, based on the unique properties of permeability single negative metamaterials, scientists are also considering introducing them into EMC protection solutions, by constructing special absorbing structures to absorb or reflect unnecessary electromagnetic energy, so as to achieve better anti-interference effects, so as to meet the requirements of spectral efficiency for 5G and even 6G wireless communication networks. Summary of the invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention proposes a chip electromagnetic protection shielding diaphragm based on magnetic permeability single negative metamaterial, and its specific technical solution is as follows: A chip electromagnetic protection shielding diaphragm based on magnetic permeability single negative metamaterial, in which multiple groups of open resonant rings with gradually changing widths are arranged, each group of open resonant rings includes three resonant single rings, the three resonant single rings are arranged in sequence according to their widths, and metal strips are added between the resonant single rings.

[0005] Preferably, based on the widths of the three resonant single rings in the first group of open resonant rings, the widths of the resonant single rings in each subsequent group of open resonant rings are correspondingly increased compared to the widths of the resonant single rings in the previous group of open resonant rings.

[0006] Preferably, the three resonant single rings have the same thickness.

[0007] Preferably, resistors are embedded in the three resonant single rings of each group of open resonant rings, and the three resonant single rings arranged in descending order of width correspond to the first resistor R1, the second resistor R2 and the third resistor R3, respectively. The resistance values ​​of the second resistor R2 and the third resistor R3 are equal, and the resistance value of the first resistor R1 is greater than the resistance value of the second resistor R2.

[0008] Preferably, there are three FR-4 dielectric layers in the shielding diaphragm, and PP material is added between adjacent FR-4 dielectric layers.

[0009] Compared with traditional electromagnetic shielding structures such as electromagnetic bandgap structures and shielding material-like shielding structures, the shielding diaphragm structure of the present invention has the characteristics of low profile, small lateral size, and wide operating frequency band. It is suitable for miniaturized chip structure protection and can effectively solve the electromagnetic interference problem generated in small compartment packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of a chip electromagnetic protection shielding diaphragm based on a single negative permeability metamaterial according to an embodiment of the present invention; Figure 2 is a schematic diagram of a shielding packaging scenario in which a shielding diaphragm according to an embodiment of the present invention is applied; Figure 3 is a schematic diagram of S parameters of a packaging scenario without a shielding diaphragm according to an embodiment of the present invention; Figure 4 Yes Figure 1 A schematic diagram showing a group of open resonant rings in the magnetic resonance unit; Figure 5 Is Figure 4 Schematic diagram of an array formed by gradually changing the width of magnetic resonance units; Figure 6 and Figure 7 is a graph of electromagnetic parameters of magnetic resonance units of different widths according to an embodiment of the present invention, wherein Figure 6 is the dielectric constant curve, Figure 7 is a schematic diagram of magnetic permeability curve; Figure 8 is a schematic diagram of a simulated application environment of a shielding diaphragm according to an embodiment of the present invention; Fig. 9 is a S11 parameter analysis curve diagram of the metal shielding box with or without a shielding diaphragm in an embodiment of the present invention; Fig.10 The S31 parameter analysis curve diagram of the metal shielding box with or without a shielding diaphragm in the embodiment of the present invention is shown in FIG. Fig.11It is a S21 parameter analysis curve diagram of the metal shielding box with or without a shielding diaphragm in the embodiment of the present invention. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical scheme and technical effect of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0012] like Figure 1 As shown, a chip electromagnetic protection shielding diaphragm based on a single-negative magnetic permeability metamaterial of the present embodiment has a plurality of groups of open resonant rings with gradually varying widths arranged in the shielding diaphragm, each group of open resonant rings includes three resonant single rings, and the three resonant single rings are arranged in sequence according to their widths, and a metal strip Lk is added between each resonant single ring, and the metal strip Lk can introduce additional magnetic resonance to further enhance the shielding effect.

[0013] The widths of the three resonant single rings in the first group of open resonant rings are 3 mm, 3.5 mm, and 4 mm, respectively. The widths of the three resonant single rings in each subsequent group of open resonant rings are increased by 0.3 mm compared with the widths of the three resonant single rings in the previous group of open resonant rings.

[0014] Resistors are embedded in the three resonant single rings of each group of open resonant rings. The three resonant single rings arranged in descending order of width correspond to the first resistor R1, the second resistor R2 and the third resistor R3 respectively. The resistance value of the first resistor R1 is 100 ohm, and the resistance values ​​of the second resistor R2 and the third resistor R3 are 15 ohm.

[0015] In the shielding membrane, there are three layers of FR-4 dielectric layers, with a relative dielectric constant of 4.4, a loss tangent of 0.002, and the thickness of the three layers of FR-4 dielectric layers: tsub1 = 0.72mm; tsub2 = 0.48mm; tsub3 = 0.46mm. The length of the dielectric substrate is the same as the length of the shielding cavity, which is 31.5mm, and the width w is 5.6mm; the dielectric constant of the pp material added between adjacent FR-4 dielectric layers is 4.1, and the loss tangent is 0.001. The thickness of the two layers of pp material is: tpp1 = tpp2 = 0.18mm; the thickness of the copper foil used is 0.035mm.

[0016] The thicknesses L1, L2, and L3 of the three resonant single rings are all 0.6 mm, and the gap g between each resonant single ring is 0.2 mm.

[0017] like Figure 2As shown, it is a simple shielding packaging scenario, which represents the commonly used shared packaging in practice. The shielding diaphragm of the present invention is placed in a metal shielding box and pasted in the center of the shielding box. It can be used to achieve a shielding effect in a wide operating frequency band and effectively prevent the internal chip radiation leakage. The cross-sectional height of the open resonant ring in the shielding diaphragm is much smaller than the height of the shielding box cavity, which is very beneficial to today's increasingly integrated circuit structures. This allows enough space inside the cavity so that the entire cross-section has space to fill the shielding material and the conventional shielding structure.

[0018] like Figure 3 As shown in the figure, it is the S parameter without the shielding membrane of the present invention. It can be found that the S parameter deteriorates near 6.43Ghz and 10.21Ghz, and the reflection and coupling are greatly improved. This phenomenon is mainly determined by the different internal modes caused by the package size of the shielding can. It can be predicted that in the actual shared shielding package, similar electromagnetic interference problems will also exist, affecting the working performance of each chip inside the package.

[0019] like Figure 4 As shown, Figure 1 A group of open resonant rings in the array is regarded as a magnetic resonance unit. The unit adopts magnetic single negative metamaterial and is composed of three open resonant single rings. The metal strips added between the three resonant single rings constitute a new magnetic resonance unit, which can further enhance the magnetic resonance. Then, the magnetic resonance units with gradually changing widths are arrayed, such as Figure 5 shown.

[0020] The magnetic single negative metamaterial can be artificially designed to manipulate the electromagnetic parameters of the metamaterial, as follows: (1) The above formula is the derived equivalent magnetic permeability formula. is the equivalent magnetic permeability, which describes the magnetic permeability of the material at a specific frequency; F is the characteristic amplitude; ω is the angular frequency; is the attenuation coefficient, which describes the degree of attenuation of the signal by the material. It can be observed that through artificial manipulation, the magnetic permeability can be made negative near a certain frequency. This formula can be divided into two parts. The real part of the magnetic permeability represents the material's ability to store magnetic field energy, and the imaginary part represents the material's ability to dissipate magnetic field energy. In general, the negative magnetic permeability is generated because the special structure of the magnetic single negative metamaterial causes the magnetic field energy to be reversely stored and lost at certain frequencies, and because of the following formula: (2) Refractive Index n It is the reciprocal of the propagation speed of electromagnetic waves in a medium, which is determined by the relative dielectric constant ε r and relative magnetic permeability μ rAt certain frequencies, for magnetic mononegative metamaterials, the magnetic permeability μ<0, the dielectric constant ε>0, and the refractive index is an imaginary number. The real part of the refractive index of the magnetic mononegative metamaterial may be negative, which will lead to a decrease in the transmittance of electromagnetic waves. The transmittance of electromagnetic waves in this frequency range will be very low.

[0021] like Figure 6 and Figure 7 As shown in the graph of electromagnetic parameters of units with different widths w, it is obvious that at the transmission zero point, the typical characteristics of magnetic single negative metamaterials are presented, with magnetic permeability μ<0 and dielectric constant ε>0. The load resistors on both sides of the strongest current can well attenuate electromagnetic waves, further enhancing the shielding effectiveness of the metamaterial diaphragm of the present invention.

[0022] like Figure 8 The figure shows the simulated application environment of the shielding diaphragm of this embodiment. Because the chip-level shielding package is very small, at the millimeter level, it is difficult to place the two SMA connectors at the same end of the bottom without overlapping for power feeding. Therefore, a multi-layer microstrip line to stripline structure is used in the lower layer to lead the signal line to two ends perpendicular to each other. Corresponding metal shielding through holes are placed around the shielding cavity, and the shielding cavity and the shielding through holes are in contact with each other and grounded, forming a complete closed cavity.

[0023] Use a vector network analyzer that can operate at 10Mhz-43.5Ghz, such as Figures 9 to 11 As shown, through the reflection coefficient S11 of the first coaxial port, it can be seen that when the metal box shielding cavity is introduced, an additional cavity effect is introduced, resulting in a sharp deterioration of the S parameters of the transmission zero points 6.43 GHz and 10.21 GHz.

[0024] After the introduction of the metamaterial shielding membrane proposed in the present invention, it can be observed that the S21 at the two resonance points of 6.43Ghz and 10.21Ghz is intentionally moved to low frequencies, thereby transferring to low frequencies with lower risks. After adding the shielding membrane, the proximal coupling coefficient of the front resonance point is reduced from -21dB to -36dB, and the rear resonance point is reduced from -15dB to -29dB. The RF coupling coefficient is greatly reduced, and it can be observed that the transmission coefficient can be restored to about 0.5dB due to the reduction of mutual coupling. The risk of encountering signal integrity problems can be reduced in a wide band.

[0025] The above description is only a preferred implementation case of the present invention and does not limit the present invention in any form. Although the implementation process of the present invention is described in detail above, for those familiar with the art, they can still modify the technical solutions recorded in the above examples, or replace some of the technical features therein with equivalents. All modifications, equivalent replacements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A chip electromagnetic protection shielding membrane based on magnetic permeability single negative metamaterial, characterized in that: A plurality of groups of open resonant rings with gradually changing widths are arranged in the shielding diaphragm. Each group of open resonant rings includes three resonant single rings. The three resonant single rings are arranged in sequence according to their widths, and metal strips are added between the resonant single rings.

2. The shielding diaphragm according to claim 1, characterized in that Based on the widths of the three resonant single rings in the first group of open resonant rings, the widths of the resonant single rings in each subsequent group of open resonant rings are correspondingly increased compared to the resonant single rings in the previous group of open resonant rings.

3. The shielding diaphragm according to claim 1, characterized in that The three resonant single rings have the same thickness.

4. The shielding diaphragm according to claim 1, characterized in that Resistors are embedded in the three resonant single rings of each group of open resonant rings. The three resonant single rings arranged in descending order of width correspond to the first resistor R1, the second resistor R2 and the third resistor R3, respectively. The resistance values ​​of the second resistor R2 and the third resistor R3 are equal, and the resistance value of the first resistor R1 is greater than the resistance value of the second resistor R2.

5. The shielding diaphragm according to claim 1, characterized in that The shielding diaphragm has three FR-4 dielectric layers, and PP material is added between adjacent FR-4 dielectric layers.

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