A broadband via-free reusable permittivity measurement device and method

Abstract

The application provides a broadband non-via reusable permittivity measuring device and method, which comprises a metal floor, a metal gasket, a to-be-measured substrate, a periodic electromagnetic band gap structure and a standard waveguide structure; the standard waveguide structure of the test structure is sequentially provided with a standard flange and a standard waveguide from bottom to top; the periodic electromagnetic band gap structure comprises two rectangular coupling holes and periodic rectangular metal columns; feeding of the application is coupled through the standard waveguide through the coupling holes; the resonant cavity formed by the gap waveguide is used for testing the permittivity of a film or sheet-shaped medium represented by a packaging material; compared with a traditional testing method, the medium substrate of the method is simple to process, does not need to be punched and has higher testing precision.

Description

Technical Field

[0001] This invention belongs to the field of dielectric constant testing technology, and relates to electromagnetic bandgap structure technology and multimode resonant cavity technology. Specifically, it is a broadband via-free reusable dielectric constant measuring device and method based on an electromagnetic bandgap resonant cavity. Background Technology

[0002] In recent years, printed circuit boards have faced numerous challenges in the extremely high frequency band, impacting system performance and leading to lower efficiency. Against this backdrop, advanced electronic packaging has rapidly developed to improve performance in the millimeter-wave band. Advanced electronic packaging, such as wafer-level packaging, is widely used in various market segments, including 5G communications and automotive radar, driving more advanced system integration designs.

[0003] Advanced packaging technologies offer a variety of integration strategies for millimeter-wave antenna integration, including packaged antennas and on-chip antennas. Antennas and systems are significantly affected by the electromagnetic properties of the packaging materials at such high frequencies; therefore, accurately understanding the complex permittivity of the packaging material is crucial for designing such systems. In advanced packaging technologies, most dielectrics are thin-film, making it essential to measure the complex permittivity directly from the dielectric film.

[0004] Over the years, various methods for extracting material properties have emerged. These measurement methods can be broadly classified into two categories: transmission / reflection methods and resonant cavity methods. In most cases, transmission / reflection methods have a wider bandwidth but lower accuracy. The advantage of resonant methods lies mainly in their higher testing accuracy.

[0005] Against this backdrop, the present invention proposes a novel broadband via-free reusable dielectric constant measurement method, which, compared with existing testing methods, has the advantages of low cost, high testing accuracy, reusability, and low requirements for the processing of the dielectric film to be tested. Summary of the Invention

[0006] The purpose of this invention is to provide a via-free, reusable, low-cost, easy-to-process, high-precision method for measuring dielectric constant in the field of encapsulation thin film materials.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A broadband, via-free, reusable dielectric constant measurement method, characterized in that it comprises a metal ground plane 1, a metal gasket 2, a substrate under test 3, a periodic electromagnetic bandgap structure 4, and a standard waveguide structure 5.

[0009] The metal floor 1 includes a metal plate 11, pin holes 12 and screw holes 13. The metal plate is rectangular, and the pin holes and screw holes are arranged alternately on both sides of the long side of the metal plate.

[0010] The metal gasket 2 includes a rectangular window 21, a metal plate 22, a pin hole 23 and a screw hole 24 from the middle to the outside. The metal plate 22 is rectangular. The rectangular window 21 is opened in the middle of the metal plate. The pin hole 23 and the screw hole 24 are on both sides of the long side of the metal plate.

[0011] The substrate 3 to be tested is rectangular, located at the center of the metal ground plane, and its thickness is determined by the thickness of the metal gasket.

[0012] The periodic electromagnetic bandgap structure 4 consists of a metal plate 41, a coupling hole 42, and a periodic metal pillar 43 from top to bottom. The metal plate 41 is rectangular. The periodic metal pillar 43 and the metal ground plate 1 form a gap waveguide resonant cavity. The periodic metal pillar 43 and the metal ground plate 1 do not contact each other and there is an air layer in between. The coupling hole 42 is a rectangular hole located on the central axis of the metal plate, at both ends of the gap waveguide resonant cavity.

[0013] The standard waveguide structure 5 consists of, from bottom to top, a metal frustum 51, a standard waveguide 52, a cuboid metal body 53, and a standard flange 54.

[0014] As a preferred method, the frequency band to be measured is the W band, that is, the dielectric constant characteristics of the dielectric film 3 under test are measured in the W band.

[0015] As a preferred approach, W-band standard waveguides and standard flanges are used.

[0016] As a preferred embodiment, the metal floor 1, the metal gasket 2, the periodic electromagnetic bandgap structure 4, and the standard waveguide structure 5 are 50 mm long and 33 mm wide.

[0017] As a preferred embodiment, the two coupling holes 42 are located on both sides of the gap waveguide resonant cavity. The length and width of the coupling holes 42 are 1.1 mm and 0.35 mm, respectively. The coupling holes are located on the central axis of the long side of the electromagnetic bandgap structure metal plate 41, and the distance between them and the electromagnetic bandgap structure in the long side direction is 3 mm.

[0018] As a preferred embodiment, the side lengths of the periodic metal pillars 43 are 0.4 mm, 0.4 mm and 0.7 mm, respectively, and the size of the gap waveguide resonant cavity formed is 2.54 mm * 26 mm * 0.8 mm.

[0019] As a preferred embodiment, the thickness of the metal gasket 2 is 0.8 mm.

[0020] The working principle of this invention is as follows:

[0021] A gap waveguide resonant cavity is constructed using a periodic electromagnetic bandgap structure and a ground plane. The dielectric substrate under test is placed in the resonant cavity, and electromagnetic energy is fed into the resonant cavity through two coupling holes. Based on the basic principle of the resonant cavity, the transmission coefficient of the structure is measured using a network analyzer. The complex permittivity of the dielectric under test is calculated based on the resonant frequency and quality factor of the transmission coefficient.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. It has a wide test bandwidth and can measure the entire W band. After size transformation, it can measure other bands.

[0024] 2. The resonant measurement method is adopted, resulting in high testing accuracy.

[0025] 3. It has low requirements for the processing of dielectric films and does not require metallized vias.

[0026] 4. The processing cost is low and the product is reusable.

[0027] 5. Using a rectangular waveguide as the feed structure, instead of a microstrip line and ground-signal-ground (GSG) probe, makes it less susceptible to electromagnetic interference from the environment and results in higher test accuracy. Attached Figure Description

[0028] Figure 1 This is an overall structural diagram of the broadband via-free reusable dielectric constant measurement method provided by the present invention.

[0029] Figure 2 This is a side view of the broadband via-free reusable dielectric constant measurement method provided by the present invention.

[0030] Figure 3 This is a structural diagram of the metal ground plane for the broadband via-free reusable dielectric constant measurement method provided by the present invention.

[0031] Figure 4 This is a structural diagram of the metal gasket for the broadband via-free reusable dielectric constant measurement method provided by the present invention.

[0032] Figure 5 This is a diagram of the periodic electromagnetic bandgap structure of the broadband via-free reusable dielectric constant measurement method provided by this invention.

[0033] Figure 6 This is a standard waveguide structure diagram of the broadband via-free reusable dielectric constant measurement method provided by the present invention.

[0034] Figure 7 This is a schematic diagram of the measurement method of the broadband via-free reusable dielectric constant measurement method provided by the present invention. Detailed Implementation

[0035] The following specific examples illustrate the implementation of the present invention. The present invention can be applied in other different ways, and those skilled in the art can understand the invention based on the content of this specification.

[0036] like Figure 1 As shown, a broadband via-free reusable dielectric constant measuring device includes a metal ground plate 1, a metal pad 2, a substrate to be measured 3, a periodic electromagnetic bandgap structure 4, and a standard waveguide structure 5.

[0037] like Figure 3 As shown, the metal floor 1 includes a metal plate 11, pin holes 12 and screw holes 13. The metal plate is rectangular, and the pin holes and screw holes are arranged alternately on both sides of the long side of the metal plate. The metal plate 11 is 50mm long, 30mm wide and 5mm high. The diameter of the pin holes 12 is 1.65mm and the screw holes 13 are standard M2 screw holes. The pin holes 12 and screw holes 13 are 2.5mm away from the edge of the metal plate 11.

[0038] like Figure 4 As shown, the metal gasket 2 includes a rectangular window 21, a metal plate 22, a pin hole 23, and a screw hole 24 from the middle to the outside. The metal plate 22 is rectangular, the rectangular window 21 is located in the middle of the metal plate, and the pin hole 23 and screw hole 24 are on both sides of the long side of the metal plate. The rectangular window 21 is 40mm long and 23mm wide. The metal plate 22 is 50mm long, 30mm wide, and 0.8mm high. The pin hole 23 has a diameter of 1.65mm, the screw hole 24 has a diameter of 2.1mm, and the pin hole 23 and screw hole 24 are 2.5mm away from the edge of the metal plate 22.

[0039] The substrate 3 to be tested is rectangular, with a length of 33mm, a width of 22mm, and a height of 0.1mm, and is located at the center of the metal floor.

[0040] like Figure 5 As shown, the periodic electromagnetic bandgap structure 4 consists of a metal plate 41, a coupling hole 42, and a periodic metal pillar 43 from top to bottom. The metal plate 41 is rectangular. The periodic metal pillar 43 and the metal ground plate 1 form a gap waveguide resonant cavity. The periodic metal pillar 43 and the metal ground plate 1 do not contact each other. The coupling hole 42 is a rectangular hole located on the central axis of the metal plate, at both ends of the gap waveguide resonant cavity. The two coupling holes 42 are located on both sides of the gap waveguide resonant cavity. The length and width of the coupling hole 42 are 1.1 mm and 0.35 mm, respectively. The coupling hole is located on the central axis of the long side of the electromagnetic bandgap structure metal plate 41, and the distance between it and the electromagnetic bandgap structure in the long side direction is 3 mm. The side lengths of the periodic metal pillars 43 are 0.4 mm, 0.4 mm, and 0.7 mm, respectively. The dimensions of the gap waveguide resonant cavity formed are 2.54 mm * 26 mm * 0.8 mm.

[0041] like Figure 6 As shown, the standard waveguide structure 5 consists of a metal frustum 51, a standard waveguide 52, a cuboid metal body 53, and a standard flange 54, from bottom to top.

[0042] The broadband via-free reusable dielectric constant measurement method provided by this invention has advantages such as wide test bandwidth, high test accuracy, no need for metallized vias, low processing cost, and reusability. It constructs a gap waveguide resonant cavity through a periodic electromagnetic bandgap structure and a ground plane. The dielectric substrate under test is placed in the resonant cavity, and electromagnetic energy is fed into the resonant cavity through two coupling holes. Based on the basic principle of the resonant cavity, the transmission coefficient of the structure is measured by a network analyzer. The complex dielectric constant of the dielectric under test is calculated based on the resonant frequency and quality factor of the transmission coefficient.

[0043] The above-described embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A broadband, via-free, reusable dielectric constant measuring device, characterized in that: It consists of, in sequence, a metal ground plane, a metal gasket, a substrate under test, a periodic electromagnetic bandgap structure, and a standard waveguide structure; The metal floor is located at the bottom of the reusable dielectric constant measuring device, and the metal pad is located above the metal floor; The substrate under test is located between a metal ground plane and a periodic electromagnetic bandgap structure; the periodic electromagnetic bandgap structure is located above the metal pad; and the standard waveguide structure is located above the periodic electromagnetic bandgap structure.

2. The broadband via-free reusable dielectric constant measuring device according to claim 1, characterized in that: The metal floor includes a metal plate, pin holes, and screw holes. The metal plate is rectangular, and the pin holes and screw holes are arranged alternately on both sides of the long side of the metal plate. The metal gasket includes a rectangular window, a metal plate, pin holes, and screw holes from the middle to the outside. The metal plate is rectangular, the rectangular window is located in the middle of the metal plate, and the pin holes and screw holes are on both sides of the long side of the metal plate. The substrate to be tested is rectangular, located at the center of the metal floor, and its thickness is determined by the thickness of the metal pad. The periodic electromagnetic bandgap structure consists of a metal plate, a coupling hole, and a periodic metal pillar from top to bottom. The metal plate is rectangular, and the periodic metal pillar and the metal ground plate form a gap waveguide resonant cavity. The periodic metal pillar and the metal ground plate do not contact each other and there is an air layer in between. The coupling hole is a rectangular hole located on the central axis of the metal plate, at both ends of the gap waveguide resonant cavity. The standard waveguide structure, from bottom to top, consists of a metal frustum, a standard waveguide, a cuboid metal body, and a standard flange.

3. The broadband via-free reusable dielectric constant measuring device according to claim 2, characterized in that: The number of standard flanges is two; the standard flanges are used to connect to the waveguide port test of the vector network analyzer.

4. The broadband via-free reusable dielectric constant measuring device according to claim 1, characterized in that: The standard waveguide structure couples part of the energy into the resonant cavity through a rectangular coupling hole.

5. The broadband via-free reusable dielectric constant measuring device according to claim 2, characterized in that: The gap waveguide resonant cavity includes an electromagnetic bandgap structure composed of periodic metal pillars.

6. The broadband via-free reusable dielectric constant measuring device according to claim 5, characterized in that: The periodic metal pillars do not directly contact the metal floor, but instead confine electromagnetic energy within the resonant cavity through the band-stop characteristics of the electromagnetic bandgap.

7. The measurement method of the broadband via-free reusable dielectric constant measuring device according to claim 1, characterized in that: A gap waveguide resonant cavity is constructed using a periodic electromagnetic bandgap structure and a metal ground plane. The dielectric substrate under test is placed in the gap waveguide resonant cavity, and electromagnetic energy is fed into the gap waveguide resonant cavity through a coupling hole. The transmission coefficient of the gap waveguide resonant cavity is measured using a network analyzer, and the complex permittivity of the dielectric under test is calculated based on the resonant frequency and quality factor of the transmission coefficient.

8. The measurement method according to claim 7, characterized in that: The electromagnetic energy of the coupled portion enters the gap waveguide resonant cavity, and the corresponding relative permittivity is calculated based on the frequency and quality factor of the resonant peaks of different modes.

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