A graphene absorbing metasurface decoupling design method

Abstract

The present invention belongs to the technical field of decoupling design methods, and specifically relates to a graphene absorbing super surface decoupling design method, comprising the following steps: based on the impedance matching theory, establishing a physical model of a combined structure absorbing material; calculating the square resistance of the absorbing layer; using CST software to realize geometric structure modeling of the absorbing material; obtaining simulation parameters of absorbing characteristics; preparing graphene by chemical vapor deposition CVD method, and preparing super surface absorbing material samples by laser etching technology; testing absorbing characteristics and inter-chip isolation. Based on the impedance matching characteristics, the present invention studies the electromagnetic loss characteristics of graphene films with different conductivity, improves the electromagnetic wave absorption rate, adopts a cross-shaped and four-concave combination structure, uses simulation software to realize the optimization design of super surface units, and realizes dual-frequency resonance; and uses ceramics to prepare an ultra-thin dielectric layer with stable chemical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of decoupling design methods, and in particular relates to a graphene absorbing supersurface decoupling design method. Background Art

[0002] In recent years, the domestic production rate of 10Gb / s low-speed chips in my country has reached 80%, while the domestic production rate of chips for high-speed transmission above 40Gb / s (typical frequency bands 45GHz and 65GHz) is less than 20%. Severe electromagnetic interference and low isolation have become key issues restricting the localization of high-speed chips, limiting the widespread application of chips in the field of optical communications. Traditional methods use increasing the distance between chips or loading filters to suppress interference and improve isolation, but they do not meet the development trend of miniaturization, integration and multi-band. Therefore, there is an urgent need for a new method to effectively improve the isolation between 45GHz and 65GHz high-speed transmission chips without increasing the size between chips.

[0003] By using absorbing materials in the electromagnetic compatibility (EMC) design of communication equipment, applying absorbing materials on the coupling path of the equipment, improving the isolation of the equipment and solving the coupling interference. The absorbing materials used more frequently at home and abroad include silicone rubber, carbonyl iron, ferrite, magnetic alloy powder, ITO film, graphene film, etc.

[0004] The United States, Japan, Western Europe and other countries are in a leading position in the research of electromagnetic wave absorption technology. Advanced thin film metamaterials have been applied to communication equipment, and the isolation has been improved by 5-15dB (2GHz-20GHz); in response to the demand for wave absorbing materials, a Japanese company has developed a doped ceramic wave absorbing material coating to filter out interference between chips, and the isolation has been improved by 7-10dB (8GHz-18GHz). A domestic research institute uses silicone rubber wave absorbing patches on the surface of coplanar antennas of ships, and the isolation has been improved by 7-15dB (4.5GHz-6GHz); the 35GHz ITO thin film wave absorbing material developed by a company has been tried in communication equipment, and the isolation has been improved by 8dB (@35GHz), solving the problem of electromagnetic interference.

[0005] At present, the working frequency band of thin-film absorbing materials developed by my country for solving electromagnetic interference in chips is 2GHz to 40GHz. They generally have single frequency band and narrowband characteristics. Limited by absorbing design technology and high-precision processing technology, they cannot currently meet the demand for 45GHz and 65GHz dual-frequency absorbing materials between chips with high-speed transmission above 40Gb / s. There is mutual coupling between chips. When the signal is at high frequency, the electromagnetic interference signal is enhanced. When two or more chips are placed in a package tube shell, the electromagnetic waves radiated by chip 3 are absorbed by chip 1 and chip 2 through spatial radiation and cavity resonance, which reduces the isolation performance of each port between chips. The traditional method uses increasing the distance between chips or loading filters to suppress interference and improve isolation, but it does not meet the development trend of miniaturization, integration and multi-band. Summary of the invention

[0006] In view of the technical problem that the above-mentioned traditional methods do not meet the development trend of miniaturization, integration and multi-band, the present invention provides a graphene absorbing metasurface decoupling design method, which improves the isolation between chips by absorbing spatial electromagnetic interference signals.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A graphene absorbing metasurface decoupling design method comprises the following steps:

[0009] S1. Based on the impedance matching theory, establish the physical model of the composite structure absorbing material;

[0010] S2. Calculate the square resistance of the absorbing layer;

[0011] S3. Use CST software to realize the geometric structure modeling of absorbing materials;

[0012] S4, obtaining wave absorption characteristic simulation parameters;

[0013] S5. Prepare graphene by chemical vapor deposition (CVD) and prepare super surface absorbing material samples by laser etching technology;

[0014] S6. Test the wave absorption characteristics and isolation between chips.

[0015] The physical model of the combined structure absorbing material in S1 includes a dielectric layer and an absorbing layer, and the absorbing layer is etched on the dielectric layer to form a metasurface unit.

[0016] The dielectric layer is made of one or more of glass, ceramic, polycarbonate, polydimethylsiloxane (PDMS), polyimide, polyterephthalate plastic, polyurethane and polydimethylsiloxane;

[0017] The wave absorbing layer is made of one or more of a graphene film, an ITO film, a metal grid and reduced graphene oxide.

[0018] The metasurface unit includes a first unit and a second unit, the first unit is a cross-shaped structure, the second unit is a four-concave structure, the cross-shaped structure of the first unit matches the four-concave structure of the second unit, and the four cross-shaped structures of the first unit are respectively inserted into the four grooves of the four-concave structure of the second unit.

[0019] The method for using CST software to achieve geometric structure modeling of absorbing materials in S3 is: using CST electromagnetic simulation software to model, for the spatial layout of two or more chips and metasurface absorbing materials, designing the spatial electromagnetic wave transmission path, obtaining efficient absorption of the spatial electromagnetic waves of the third chip by the absorbing material, reducing electromagnetic interference to the first chip and the second chip, and improving the isolation between chips.

[0020] The method for preparing graphene by chemical vapor deposition (CVD) in S5 is as follows: comprising the following steps: S5.1, under low pressure conditions, using copper as a metal catalyst substrate and methane and long-chain alkanes as carbon sources; S5.2, the carbon source is adsorbed on the catalyst surface; S5.3, the carbon source is desorbed; S5.4, the carbon source is dehydrogenated and decomposed; S5.5, carbon atoms migrate on the catalyst surface; S5.6, carbon atoms directly nucleate on the surface and grow into graphene; S5.7, carbon atoms are integrated into the metal copper bulk phase at high temperature; S5.8, carbon atoms diffuse in the metal body; S5.9, cooling, carbon atoms are precipitated from the metal bulk phase, and graphene is formed and grown on the surface.

[0021] The method for preparing a supersurface absorbing material sample using laser etching technology in S5 is: focusing a low-power laser beam with high beam quality into an extremely small spot, forming a very high power density at the focus, so that the blue graphic part is vaporized instantly to form a supersurface structural unit.

[0022] In S6, the wave absorbing properties of the wave absorbing layer are obtained by using the bow method test.

[0023] The method for testing the isolation between chips in S6 is: completing the performance evaluation and installation verification of the sample of graphene film super-surface absorbing material for chips, using a microwave signal source and a vector network analyzer to test the scattering parameter S between chips with and without absorbing material. 13 and S 23 .

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] Based on the impedance matching characteristics, the present invention studies the electromagnetic loss characteristics of graphene films with different conductivity, improves the electromagnetic wave absorption rate, adopts a cross-shaped and four-concave combination structure, uses simulation software to optimize the design of the supersurface unit, and realizes dual-frequency resonance; ceramics are used to prepare an ultra-thin dielectric layer with stable chemical properties. Compared with traditional absorbing materials, the thickness of the supersurface absorbing material of the present invention is 0.5mm, and the absorbing frequency band is expanded from 2GHz to 40GHz to the high frequency band, achieving an absorption rate of more than 90% in the range of 35GHz-45GHz and 55GHz-69GHz, working in the U band and V band, and having the characteristics of ultra-thinness, wide frequency band, and strong absorbing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0027] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0028] Figure 1 is a flow chart of the steps of the present invention;

[0029] Figure 2 It is a schematic diagram of the physical model structure of the combined structure absorbing material of the present invention;

[0030] Figure 3 is a structural schematic diagram of the first unit of the present invention;

[0031] Figure 4 is a structural schematic diagram of the second unit of the present invention;

[0032] Figure 5 It is a schematic diagram of the structure of the first unit and the second unit of the present invention cooperating with each other;

[0033] Figure 6 This is a test result diagram of the present invention.

[0034] Wherein: 1 is a dielectric layer, 2 is an absorbing layer, 201 is a first unit, and 202 is a second unit. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In this embodiment, if Figure 1 As shown, the influence of the multi-band and strong wave absorption characteristics of graphene metasurface absorbing materials on the isolation between chips is studied. The mathematical model of dispersion modulation of graphene metasurface absorbing materials is established using impedance matching theory, and the influence of the square resistance, shape, spacing, and dielectric layer thickness of the absorbing materials on the frequency shift and absorption characteristics of electromagnetic waves is studied to obtain a dual-frequency resonant structure; CST electromagnetic simulation software is used to model and conduct a designable study on the spatial electromagnetic wave transmission path for the spatial layout of two or more chips and metasurface absorbing materials, and the efficient absorption of electromagnetic waves in the space of the third chip by the absorbing material is obtained, thereby reducing the electromagnetic interference to the first chip and the second chip, and improving S 13 and S 23 , improving the isolation between chips.

[0040] Schematic diagram of the structure of graphene supersurface absorbing material Figure 2 As shown in Figure 1, it includes two parts: absorbing layer and dielectric layer. CST software is used to realize geometric structure modeling of absorbing materials, as shown in Figure 1. Figure 2 The absorbing material includes a dielectric layer 1 and an absorbing layer 2 structure, the dielectric layer represents a ceramic with a thickness h and a dielectric constant ε, and the absorbing layer represents a super surface unit structure etched on a graphene film with a square resistance S and symmetric about an axis, and the super surface unit includes a first unit 201 and a second unit 202, as shown in FIG. Figure 3 As shown, the first unit 201 is a cross-shaped structure; Figure 4 As shown, the second unit 202 is a four-concave structure. The cross-shaped structure of the first unit 201 matches the four-concave structure of the second unit 202, as shown in FIG. Figure 5 As shown, the four cross-shaped structures of the first units 201 are respectively inserted into the four grooves of the four-concave structure of the second unit 202. The square resistance S of the graphene film is 200Ω / sq.±20Ω / sq.; the dielectric constant ε of the ceramic is 8.2, the thickness h is 0.5mm±0.05mm, and the loss tangent value is 0.0075.

[0041] Preparation of graphene by CVD: Under low pressure conditions, copper is used as the metal catalyst substrate and methane, long-chain alkanes, etc. are used as carbon sources. The basic steps for preparing single-layer / multi-layer graphene are as follows: (1) The carbon source is adsorbed on the catalyst surface; (2) The carbon source is desorbed; (3) The carbon source is dehydrogenated and decomposed; (4) The carbon atoms migrate on the catalyst surface; (5) The carbon atoms directly nucleate on the surface and grow into graphene; (6) The carbon atoms are integrated into the metal copper bulk phase at high temperature; (7) The carbon atoms diffuse in the metal body; (8) The temperature is lowered, and the carbon atoms precipitate from the metal bulk phase and form and grow graphene on the surface.

[0042] Laser etching technology: Use CAD drawing software to draw the required absorbing material graphics, the unit size is 2.5mm×2.5mm, and the overall size is 180mm×180mm×0.5mm; use a laser photoplotter to draw a yellow and white microstructure process diagram; use a low-power laser beam with high beam quality to focus into a very small spot, forming a very high power density at the focus, so that the blue graphic part is vaporized instantly to form a super surface structure unit, such as Figure 3-5 shown.

[0043] Conformal technology between absorbing materials and chip packaging shells: Cut the metasurface absorbing materials to meet the required dimensions for packaging (typical dimensions: 10mm×13mm×0.5mm, 8mm×11mm×0.5mm, 13mm×18mm×0.5mm). Conduct research on the spatial layout of metasurface absorbing materials and chip packaging shells, use 0.5-1μm ultra-thin silver glue to fix the absorbing metasurface to the packaging shell, and attach the thin-film absorbing materials to the positive, front and back walls of the third chip. Electromagnetic waves are bound inside or on the surface of the absorbing materials, improving the chip separation and achieving conformal technology between thin-film absorbing materials and chip packaging shells.

[0044] Wave absorbing property test: Place the absorbing material on a surface with a size of 180mm×180mm, and use the bow method to test the wave absorbing property of the absorbing material. The test results are as follows: Figure 6 As shown in the figure, the absorption rate is higher than 90% in the working frequency range of 35GHz-45GHz and 55GHz-69GHz, and it works in the U band and V band.

[0045] Inter-chip isolation performance test: Completed the performance evaluation and installation verification of the sample of graphene film super-surface absorbing material for chips, and used microwave signal source and vector network analyzer to test the inter-chip scattering parameter S with and without absorbing material. 13 and S 23 In the typical frequency band of 45GHz, the isolation is increased by 7dB and 10dB respectively, and in the typical frequency band of 65GHz, the isolation is increased by 13dB and 15dB respectively, and the performance is significantly improved.

[0046] Compared with traditional absorbing materials, the thickness of the metasurface absorbing material is 0.5mm, and the absorbing frequency band is expanded from 2GHz to 40GHz to the high frequency band, achieving an absorption rate of more than 90% in the range of 35GHz-45GHz and 55GHz-69GHz. It works in the U band and V band, and has the characteristics of ultra-thinness, wide frequency band and strong absorbing.

[0047] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A graphene absorbing metasurface decoupling design method, Features: The following steps are involved: S1. Based on impedance matching theory, a physical model of a combined structure absorbing material is established; the physical model of the combined structure absorbing material in S1 includes a dielectric layer and an absorbing layer, and the absorbing layer is etched on the dielectric layer to form a super surface unit; the super surface unit includes a first unit and a second unit, the first unit is a cross-shaped structure, and the second unit is a four-concave structure, the cross-shaped structure of the first unit is matched with the four-concave structure of the second unit, and four cross-shaped structures of the first unit are respectively inserted into four grooves of the four-concave structure of the second unit; S2. Calculate the square resistance of the absorbing layer; S3, using CST software to achieve geometric structure modeling of absorbing materials; the method of using CST software to achieve geometric structure modeling of absorbing materials in S3 is: using CST electromagnetic simulation software to model, for the spatial layout of two or more chips and metasurface absorbing materials, designing a spatial electromagnetic wave transmission path, obtaining efficient absorption of the spatial electromagnetic waves of the third chip by the absorbing material, reducing electromagnetic interference to the first chip and the second chip, and improving isolation between chips; S4, obtaining wave absorption characteristic simulation parameters; S5, preparing graphene by chemical vapor deposition CVD method, and preparing super surface absorbing material samples by laser etching technology; the method of preparing graphene by chemical vapor deposition CVD method in S5 is: comprising the following steps: S5.1, under low pressure conditions, using copper as a metal catalyst substrate, methane and long-chain alkanes as carbon sources; S5.2, adsorption of carbon source on the catalyst surface; S5.3, desorption of carbon source; S5.4, dehydrogenation and decomposition of carbon source; S5.5, migration of carbon atoms on the catalyst surface; S5.6, direct nucleation of carbon atoms on the surface and growth into graphene; S5.7, carbon atoms are integrated into the metal copper bulk phase at high temperature; S5.8, carbon atoms diffuse in the metal body; S5.9, cooling, carbon atoms are precipitated from the metal bulk phase, and graphene is formed and grown on the surface; S6. Test the wave absorption characteristics and isolation between chips.

2. A graphene absorbing metasurface decoupling design method according to claim 1, Features: The dielectric layer is made of one or more of glass, ceramic, polycarbonate, polydimethylsiloxane (PDMS), polyimide, polyterephthalate plastic, polyurethane and polydimethylsiloxane; The wave absorbing layer is made of one or more of a graphene film, an ITO film, a metal grid and reduced graphene oxide.

3. A graphene absorbing metasurface decoupling design method according to claim 1, Features: The method for preparing a supersurface absorbing material sample using laser etching technology in S5 is: focusing a low-power laser beam with high beam quality into an extremely small spot, forming a very high power density at the focus, so that the blue graphic part is vaporized instantly to form a supersurface structural unit.

4. A graphene absorbing metasurface decoupling design method according to claim 1, Features: In S6, the wave absorbing properties of the wave absorbing layer are obtained by using the bow method test.

5. A decoupling design method for a graphene absorbing metasurface according to claim 1, characterized in that: The method for testing the isolation between chips in S6 is: completing the performance evaluation and installation verification of the sample of graphene film super-surface absorbing material for chips, using a microwave signal source and a vector network analyzer to test the scattering parameter S between chips with and without absorbing material. 13 and S 23 .

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