A microwave-absorbing film based on artificial surface plasmon theory

Abstract

The present invention discloses an absorbing film based on artificial surface plasmon theory, wherein the absorbing film structure consists of two parts: a dielectric layer and a metal pattern layer. The dielectric layer is a flat square layer composed of a single dielectric; the metal pattern layer is attached to the surface of the dielectric layer and consists of three structural rings, each of which is composed of artificial surface plasmon structural units uniformly arranged in a circular shape. Each artificial surface plasmon structural unit intercepts a sector-shaped portion of an array of thirteen concentric metal circular rings and is connected in series in the center by a straight metal strip. The present invention can effectively reduce electromagnetic radiation within its operating frequency band, and because it is ultra-thin, broadband, easy to process, and has a high operating frequency band, it is particularly suitable for suppressing high-frequency microwave radiation leakage in system-level packaging such as chips and printed circuit boards.

Description

Technical Field

[0001] The present invention relates to the fields of electromagnetic compatibility, artificial surface plasmons and system-level packaging, and in particular to an absorbing film structure based on artificial surface plasmons and its application in microwave frequency band radiation suppression in system-level packaging. Background Art

[0002] The rapid development of communications technology has placed higher demands on system-level packaging (SIP). One of the challenges is suppressing radiation leakage from the packaging structure. Unwanted electromagnetic signals in the package can interfere with the functions of other modules, while strong radiation leakage can also cause device failure. The traditional solution to this problem is to use commercially available absorbing materials to absorb unwanted radiation leaking from the packaging structure. However, existing absorbing materials generally have limitations, such as limited absorption performance, large space requirements, and high cost.

[0003] In order to achieve broadband and high-absorption radiation suppression effects at the same time, researchers have designed a variety of electromagnetic absorbers. Among them, periodically arranged frequency-selective surface absorbers can achieve good radiation suppression effects while minimizing the thickness of the absorber. However, the overall size of the periodic structure is generally large. When they are applied to miniaturized packages, the absorption performance is greatly reduced due to the limited number of structural units that can be placed. In addition, magnetic materials made of ferromagnets also have good absorption effects, but when used in miniaturized system-level packages, their limited thickness prevents them from exerting their maximum absorption potential. Today, with the popularization and large-scale application of 5G technology, the operating frequency of chips is getting higher and higher, and the signals in the package are becoming more and more complex. Therefore, the demand for broadband high-frequency absorption structures that can be applied to miniaturized system-level packaging structures is becoming more urgent.

[0004] Surface plasmons are optical surface waves that exist at the interface between metals and dielectrics. At microwave frequencies, artificially designed metal structures can mimic the properties of optical surface plasmons, also known as artificial surface plasmons. Artificial surface plasmons have important applications, such as metasurfaces, antennas, waveguides, and filters. In the past decade, new absorbing structures based on artificial surface plasmons have begun to emerge. Plasmonic absorbing structures can couple electromagnetic waves to the surface of their metal structures and utilize the dispersion characteristics of the corresponding artificial surface plasmon modes, combined with dielectric loss, to dissipate the electromagnetic waves, thereby achieving an absorbing effect. Summary of the Invention

[0005] Given the limited absorption performance of existing absorbing technologies and the need for broadband, high-performance radiation absorbers in microwave frequency bands in system-level packages (SLPs) such as chips, this paper applies artificial surface plasmon theory to design an absorbing film that effectively enhances the suppression of high-frequency microwave electromagnetic radiation. By placing this absorbing film structure horizontally above the SLP's radiation source, it effectively suppresses electromagnetic radiation leakage within the SLP's operating frequency band, thereby more effectively addressing the issue of excessive electromagnetic radiation in SLPs.

[0006] The technical solutions adopted by the present invention to solve the related technical problems are as follows:

[0007] A wave-absorbing film based on artificial surface plasmon theory consists of a dielectric layer and a metal pattern layer, wherein the metal pattern layer is attached to one side surface of the dielectric layer.

[0008] Furthermore, the dielectric layer is a flat square layer made of polyimide, with a thickness of 0.05 mm and a side length of Ls=40 mm.

[0009] Furthermore, the metal pattern layer includes three concentric structural rings; each structural ring is composed of a plurality of artificial surface plasmon structural units, and the artificial surface plasmon structural units are evenly arranged in a circular shape.

[0010] Furthermore, in the entire metal pattern layer, all artificial surface plasmon structural units have the same specifications.

[0011] Furthermore, the artificial surface plasmon structure unit includes a fan ring array and a metal strip, the fan ring array is an array of thirteen metal fan rings formed by thirteen concentric metal circular rings intercepted by the same fan shape, and the metal strip is a straight metal strip connecting the central axes of the thirteen concentric metal fan rings in series.

[0012] Furthermore, the central angle of the sector is θ=30°.

[0013] Furthermore, in the fan ring array, the inner diameter of the innermost metal fan ring is R0=4.6 mm, the width of all metal fan rings and metal strips is w=0.2 mm, and the spacing between the metal fan rings is s=0.2 mm.

[0014] Furthermore, the artificial surface plasmon structural units are arranged in the structural ring in such a manner that the circle with the smallest radius in the fan ring array is close to the center of the structural ring, and the extension line of the straight metal strip passes through the center of the structural ring.

[0015] Furthermore, the parameters of the three structural rings from inside to outside are: radius R a =2.56mm, R b=8.10mm, R c =14.10mm, interval angle θ a =60°,θ b =24°,θ c =18°; the radius is defined as the distance from the center of the structural ring to the center of the inner diameter of the innermost metal fan ring of the artificial surface plasmon structure unit, and the interval angle is defined as the angle between two adjacent artificial surface plasmon structure units and the center of the structural ring in the same structural ring.

[0016] The present invention is an absorbing structure based on artificial surface plasmon theory. It can couple electromagnetic waves to the surface of an artificially designed metal structure. Based on the dispersion characteristics of the corresponding mode of artificial surface plasmon and combined with the loss of the medium, the electromagnetic waves are dissipated. The energy of the radiation field is converted into heat energy and lost, which is specifically manifested as the radiation field being absorbed and attenuated.

[0017] The beneficial effects of the present invention are:

[0018] Without changing the original structure of the package and without affecting its function and heat dissipation, the present invention effectively suppresses the leakage of electromagnetic radiation within the operating frequency band of related electronic products, thereby preventing electromagnetic radiation from interfering with other functional modules in the system-level package, and further enabling related electronic products to meet industry standards for electromagnetic interference.

[0019] The present invention is suitable for radiation suppression in system-level packages such as chips and printed circuit boards, and has a particularly significant inhibitory effect on electromagnetic radiation in the 26.3-31.6 GHz frequency band, achieving a radiation suppression effect of 90% or more, and can be flexibly and widely used in different packages. Because it has the characteristics of a high operating frequency band and a wide bandwidth, it is particularly suitable for broadband electromagnetic radiation suppression near the Ka band in system-level packages.

[0020] The present invention has the characteristics of being ultra-thin and having a simple structure, does not need to occupy too much space, and is easy to be added to a packaging structure such as a chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] Figure 1 A schematic diagram of the disassembly of the three-dimensional structure of the absorbing film provided by the present invention;

[0023] Figure 2 A schematic diagram of the structure of the absorbing film provided by the present invention;

[0024] Figure 3 Schematic diagram of parameters and acquisition method of artificial surface plasmon structural units in the absorbing film of the present invention;

[0025] Figure 4 Schematic diagram of the arrangement parameters of the three structural rings of the absorbing film of the present invention;

[0026] Figure 5 Schematic diagram of a system-level packaging model in an embodiment of the present invention

[0027] Figure 6 is a schematic diagram of a simulation application of a system-level packaging model in an embodiment of the present invention;

[0028] Figure 7 This is a comparison chart of the maximum 3-meter electric field values radiated by the packaging structure in the embodiment;

[0029] Figure 8 A curve diagram showing a simulation comparison of the absorbing effects of the absorbing film provided by the present invention and commercial absorbing materials in a system-level packaging simulation model in an embodiment;

[0030] In the figure: (1) dielectric layer, (2) metal pattern layer, (3) artificial surface plasmon structure unit, (4) heat sink, (5) absorbing film, (6) chip or other electronic components that may generate radiation, (7) PCB base plate. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1 and Figure 2 As shown, the present invention provides an absorbing film based on artificial surface plasmon theory. The absorbing film is composed of a dielectric layer 1 and a metal pattern layer 2. The dielectric layer 1 is a flat square layer made of polyimide, with a thickness of 0.05 mm and a side length Ls of 40 mm. The metal pattern layer 2 is attached to the surface of the dielectric layer 1 and consists of three structural rings, each of which is composed of multiple artificial surface plasmon structural units 3 evenly arranged in a circular shape.

[0033] like Figure 3 Figure 2 shows the structure and parameters of a single artificial surface plasmon structure unit 3. Each artificial surface plasmon structure unit 3 is formed by intercepting a sector of an array of thirteen concentric metal rings with a central angle of θ = 30° and connected in series with a straight metal strip at the center. In the sector ring array, the inner diameter of the innermost metal sector ring is R0 = 4.6mm. The width of all metal sector rings and metal strips is w = 0.2mm, and the spacing between metal sector rings is s = 0.2mm. All artificial surface plasmon structure units 3 in the metal pattern layer 2 have the same specifications.

[0034] like Figure 4As shown in FIG. 1 , the arrangement and parameters of the artificial surface plasmon structure unit 3 in the metal pattern layer 2 are as follows: the parameters of the three structure rings from the inner to the outer are: radius R a =2.56mm, R b =8.10mm, R c =14.10mm, interval angle θ a =60°,θ b =24°,θ c =18°; the radius is defined as the distance from the center of the structural ring to the center of the inner diameter of the innermost metal fan ring of the artificial surface plasmon structure unit, and the interval angle is defined as the angle between two adjacent artificial surface plasmon structure units and the center of the structural ring in the same structural ring.

[0035] Figure 5 A schematic diagram of a system-in-package (SIP) model using the absorbing film in an application scenario is shown. The SIP model primarily consists of a heat sink 4, the absorbing film 5 provided by the present invention, a chip or other potentially radiating electronic component 6, and a PCB baseplate 7, stacked in this order. During operation, the absorbing film 5 is placed horizontally above the chip or other potentially radiating electronic component 6, with the heat sink and PCB spaced 6 mm apart, and the absorbing film and PCB spaced 2 mm apart.

[0036] like Figure 6 The figure shows a system-level package structure simulation model built in simulation software. The distance between the heat sink 4 and the PCB base plate 7 is 6 mm. When using the absorbing film 5 provided by the present invention as an absorber in this scenario, it is placed horizontally above the radiation source traces to simulate the radiation effect of a chip or other structure, with the surface with the metal pattern layer facing the radiation source. The distance between the absorbing film and the PCB is 2 mm.

[0037] like Figure 7 As shown, simulations were performed in the above-mentioned system-level packaging structure simulation model to obtain the maximum 3-meter electric field values radiated by the packaging structure with and without the absorbing film structure of the present invention. The difference between the two results reflects the radiation suppression effect of the absorbing structure. It can be clearly seen from the figure that after adding the absorbing film structure provided by the present invention, the electric field value radiated by the packaging model within the 26.3-31.6 GHz frequency band is reduced by at least 10 dB compared to without the absorbing film, achieving an absorption effect of 90% or more. Based on the simulated electric field values, the absorption rate A of the absorbing structure can be further calculated according to the following two formulas:

[0038]

[0039] E(dBμV / m)=20log10(E / (1μV))

[0040] Among them, P 无吸收体 and P 有吸收体 Represents the radiation power value E when no absorption film is added and when an absorption film is added. 无吸收体 and E 有吸收体 They represent the radiation electric field values when no absorption film is added and when an absorption film is added, respectively; E (dBμV / m) represents the electric field value in units of (dBμV / m), and E represents the electric field value in units of V / m.

[0041] like Figure 8 The figure shows a comparison of the absorption rates calculated using the absorbing film of the present invention and several other commercial absorbing materials after simulation. For ease of comparison, the size, thickness, and placement of the absorbing materials are consistent with those of the absorbing film of the present invention. The figure clearly shows that compared to commercial absorbing materials, the absorbing film structure of the present invention achieves superior radiation suppression in terms of both absorption bandwidth and absorption efficiency, achieving an absorption rate of over 90% within the 26.3-31.6 GHz frequency band. This demonstrates that the absorber structure of the present invention can effectively reduce radiation leakage throughout the entire system-level packaging scenario within its operating frequency band.

[0042] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A microwave-absorbing film based on artificial surface plasmon theory, characterized by: The absorbing film is composed of a dielectric layer and a metal pattern layer, wherein the metal pattern layer is attached to one surface of the dielectric layer; the metal pattern layer includes three concentric structural rings; each structural ring is composed of multiple artificial surface plasmon structural units; the artificial surface plasmon structural units include a fan ring array and a metal strip; the fan ring array is an array of thirteen metal fan rings formed by intercepting thirteen concentric metal circular rings with the same fan shape; the metal strip is a straight metal strip connected in series with the central axis of the thirteen metal fan rings.

2. The absorbing film based on artificial surface plasmon theory according to claim 1, characterized in that: The dielectric layer is a flat square layer made of polyimide, with a thickness of 0.05 mm and a side length of Ls=40 mm.

3. The microwave-absorbing film based on artificial surface plasmon theory according to claim 1, characterized in that: The artificial surface plasmon structural units are evenly arranged in a circular shape.

4. The microwave-absorbing film based on artificial surface plasmon theory according to claim 1, characterized in that: The central angle of the sector is θ=30°.

5. The microwave-absorbing film based on artificial surface plasmon theory according to claim 1, characterized in that: In the fan ring array, the inner diameter of the innermost metal fan ring is R0=4.6mm, the width of all metal fan rings and metal strips is w=0.2mm, and the spacing between the metal fan rings is s=0.2mm.

6. The microwave-absorbing film based on artificial surface plasmon theory according to claim 1, characterized in that: The parameters of the three structural rings from inside to outside are: radius R a =2.56mm, R b =8.10mm, R c =14.10mm, interval angle θ a =60°, θ b =24°, θ c =18°; the radius is the distance from the center of the structural ring to the center of the inner diameter of the innermost metal fan ring of the artificial surface plasmon structure unit, and the interval angle is the angle between two adjacent artificial surface plasmon structure units and the center of the structural ring in the same structural ring.

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