HTCC airtight waveguide packaging structure

Abstract

The invention provides an HTCC airtight waveguide packaging structure. The packaging structure is composed of a ceramic cover plate, multiple layers of ceramic media, metal via holes and a radio frequency layer. And the ceramic cover plate is used for performing air-tight seal welding with the multilayer ceramic dielectric to realize the air-tight characteristic of the packaging structure. The multilayer ceramic dielectric is provided with a ceramic windowing structure and a ceramic waveguide transition structure. The ceramic windowing structure is used for placing the radio frequency micro-strip, and the radio frequency micro-strip is connected with the waveguide transition structure through a gold wire. The ceramic waveguide transition structure is composed of a waveguide-like structure, a matching structure and a probe structure. The waveguide-like structure is composed of a first slot, a third slot and corresponding metal via holes which are arranged in the ceramic dielectric. The probe structure is composed of metal wires arranged on the ceramic dielectric, the interior of the matching structure is physically isolated by a single-layer ceramic dielectric, and high performance and airtight waveguide characteristics are achieved. According to the invention, the problem that the existing HTCC waveguide packaging structure cannot directly realize airtightness is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication equipment, and in particular to a HTCC airtight waveguide packaging structure. Background Art

[0002] In phased array radar / communication systems, HTCC packaging is often used to achieve high integration, miniaturization, low cost, and airtightness. HTCC offers advantages such as high machining precision, strong structural strength, and ease of miniaturization, making it a common packaging structure for bare chips. However, its poor high-frequency performance and high RF losses make it rarely used in packaging applications for extremely high-frequency systems, particularly terahertz systems.

[0003] In the RF performance of HTCC, losses primarily come from conductor loss and dielectric loss. Conductor loss can be reduced by minimizing RF trace lengths. However, terahertz systems typically employ waveguide structures to transmit RF signals with low loss. Therefore, in terahertz system applications, a waveguide structure must be incorporated into the HTCC package. Conventional waveguide structures are typically introduced into dielectric packages by arranging metal vias at equal intervals to form a closed rectangular structure, creating a waveguide-like structure. This approach results in very high high-frequency dielectric losses in the HTCC package. Directly removing the dielectric by slotting would not achieve waterproofing, salt spray resistance, or airtightness, and could easily lead to reduced bare chip performance or even failure. Therefore, HTCC packages with waveguide structures are difficult to implement. Summary of the Invention

[0004] The purpose of the present invention is to address the defects of the above-mentioned prior art and provide a HTCC airtight waveguide packaging structure to solve the problem that the existing chip airtight packaging structure cannot simultaneously meet the requirements of high-performance packaging of terahertz chips, airtightness using waveguide structures, salt spray resistance, miniaturization, etc.

[0005] The present invention proposes a HTCC airtight waveguide packaging structure. Based on the HTCC package, an HTCC-like waveguide structure is introduced, and the dielectric within the waveguide-like structure is grooved to achieve low-loss transmission of RF performance. At the same time, a layer of ceramic dielectric is reserved in the waveguide-like structure to completely cover the waveguide cavity, achieving waterproof, salt spray-proof and airtight properties of the waveguide through physical isolation. Then, a waveguide transition structure from HTCC waveguide to microstrip is introduced, and a broadband low-loss transition of RF performance is achieved through special structural matching.

[0006] The present invention adopts the following technical solutions: A HTCC airtight waveguide packaging structure includes a ceramic cover plate, a multi-layer ceramic dielectric, a radio frequency layer, and a metal pad.

[0007] The ceramic cover is welded to the multilayer ceramic dielectric. The multilayer ceramic dielectric features a ceramic window structure and a ceramic waveguide transition structure. The ceramic window structure is located within the multilayer ceramic dielectric, forming a cavity. The ceramic window structure is located in the middle of the multilayer ceramic dielectric, with two ceramic waveguide transition structures located at either end of the ceramic window structure.

[0008] The ceramic window structure has a bottom ceramic dielectric and a ceramic window step located above the bottom ceramic dielectric. The RF layer is mounted on the bottom ceramic dielectric of the ceramic window structure. The RF layer includes an RF microstrip and gold wires connected to the RF microstrip. Metal traces are provided on the ceramic window step. The metal traces are interconnected to the RF microstrip via gold wires.

[0009] The ceramic waveguide transition structure consists of slots, metal vias, and metal traces within a multilayer ceramic dielectric. The slots are divided into first, second, and third slots. The first slot does not penetrate the top single-layer ceramic dielectric, while the third slot penetrates the bottom single-layer ceramic dielectric. The interior of the second slot is physically separated by a single layer of ceramic dielectric, forming an upper and lower region. Metal traces are placed on this single-layer ceramic dielectric and connected to the metal traces on the ceramic window step. The single-layer ceramic dielectric and the metal traces form a probe structure.

[0010] The first and third slots are used to form a waveguide cavity. The second slot is used for the RF matching probe structure. The metal vias are divided into first, second, and third metal vias. The first metal via is located on the four slot walls of the first slot. The second metal via is located on the four slot walls of the second slot. The third metal via is located on the four slot walls of the third slot. The first metal via and the first slot together form a waveguide-like structure and a short-circuit branch of the ceramic waveguide transition structure. The ceramic waveguide short-circuit surface of the short-circuit branch provides the necessary RF reflection surface for the ceramic waveguide transition structure. The third metal via and the third slot together form a waveguide-like structure, providing the necessary transmission path for the RF signal.

[0011] The second metal via and the second slot form a matching structure that matches the probe structure in the ceramic waveguide transition structure, forming a waveguide transition structure with good RF performance, and transitioning the RF signal from the microstrip with low loss to the waveguide.

[0012] The metal pad is located at the opening of the third slot of the ceramic waveguide transition structure and is arranged in a circle along the outer side of the third slot in a rectangular manner. The HTCC airtight waveguide packaging structure is interconnected with external components at the metal pad by means of ball planting.

[0013] Furthermore, the ceramic cover plate is sealed and welded to the ceramic window structure in the middle.

[0014] Furthermore, the ceramic cover plate adopts the HTCC process and is a single-layer ceramic medium.

[0015] Furthermore, the multilayer ceramic dielectric is formed by sintering multiple single-layer ceramic dielectrics through the HTCC process.

[0016] Furthermore, the first slot is located in the middle and upper side of the second slot, and the third slot is located in the middle and lower side of the second slot.

[0017] Furthermore, the single-layer ceramic medium where the probe structure is located fully covers the second slot, so that the ceramic waveguide transition structure achieves airtightness.

[0018] Beneficial effects of the present invention: 1. Compared to existing conventional hermetic packaging structures, this invention, based on the HTCC process, offers smaller dimensions, higher machining precision, and improved consistency through integrated processing, making it more suitable for miniaturized applications. It improves system integration and reliability, reduces weight, and saves size. Compared to existing HTCC packaging, this invention introduces a waveguide-like structure by arranging metal vias at equal intervals to form a rectangular closed cavity. Dielectric slots are then created within the rectangular cavity to achieve low-loss RF transmission.

[0019] 2. This invention incorporates a waveguide-to-microstrip transition structure within the HTCC package and incorporates a special matching structure within the dielectric slots, achieving low-loss RF transmission transition and making it more suitable for high-frequency applications. This invention also incorporates a pre-reserved ceramic dielectric layer within the HTCC-like waveguide structure, achieving airtightness through the physical isolation of the waveguide. The HTCC airtight waveguide package structure of this invention is an integrated package, reducing assembly complexity, resulting in a smaller size, improved consistency, and higher reliability.

[0020] 3. The HTCC airtight waveguide structure of the present invention uses a ceramic substrate, which is chemically more stable and has salt spray resistance. The HTCC airtight waveguide structure of the present invention uses a ceramic substrate, which does not absorb water, has a stable dielectric constant, and has high reliability and stable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 Exploded view of the HTCC airtight waveguide packaging structure of the present invention.

[0023] Figure 3 Schematic diagram of the multilayer ceramic dielectric of the present invention.

[0024] Figure 4 This is a top view of the HTCC airtight waveguide packaging structure of the present invention after removing the ceramic cover plate.

[0025] Figure 5 It is a partial schematic diagram of the HTCC waveguide transition structure of the present invention.

[0026] Figure 6 It is a side view of the HTCC waveguide transition structure of the present invention.

[0027] Figure 7 Schematic diagram of the bottom pad of the HTCC airtight waveguide packaging structure of the present invention.

[0028] Figure 8 It is a side view of an embodiment of the present invention.

[0029] Figure 9 It is a schematic diagram of the assembly of an embodiment of the present invention.

[0030] In the picture: 1-Ceramic cover plate; 2-Multilayer ceramic dielectric; 0-single-layer ceramic dielectric; 1-Ceramic window structure; 2-ceramic window bottom ceramic medium, 222-ceramic window step; 3-Ceramic waveguide transition structure; 4-first slot, 232-second slot; 233 - third slot, 234 - first metal via; 235 - second metal via, 236 - third metal via; 237-Ceramic waveguide short-circuit board; 24-probe structure; 3-RF layer; 31-RF microstrip; 32-gold thread; 4-Metal pad; 5-Composite board. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] like Figure 1-7 As shown, a HTCC airtight waveguide packaging structure of the present invention includes a ceramic cover plate 1, a multilayer ceramic dielectric 2, a radio frequency layer 3, and a metal pad 4.

[0033] The ceramic cover plate 1 is sealed and welded on the multi-layer ceramic dielectric 2 and located on the central ceramic window structure 22 to achieve the airtightness of the packaging structure. The ceramic cover plate 1 adopts the HTCC process and is a single-layer ceramic dielectric 21.

[0034] The multilayer ceramic dielectric 2 is formed by sintering multiple single-layer ceramic dielectrics 21 through the HTCC process. It features a ceramic window structure 22 and a ceramic waveguide transition structure 23. The ceramic window structure 22 is positioned within the multilayer ceramic dielectric 2, forming a cavity structure. The ceramic window structure 22 is located in the center of the multilayer ceramic dielectric 2, while two ceramic waveguide transition structures 23 are located at either end of the ceramic window structure 22.

[0035] The ceramic window structure 22 has a bottom ceramic dielectric 221 and a ceramic window step 222 located on the bottom ceramic dielectric 221. The RF layer 3 is mounted on the bottom ceramic dielectric 221 of the ceramic window structure 22. The RF layer 3 includes an RF microstrip 31 and a gold wire 32 connected to the RF microstrip 31. Metal traces are provided on the ceramic window step 222. The metal traces are interconnected to the RF microstrip 31 via the gold wire 32.

[0036] The ceramic waveguide transition structure 23 is composed of slots, metal vias, and metal traces within the multilayer ceramic dielectric 2. The slots are divided into a first slot 231, a second slot 232, and a third slot 233. The first slot 231 does not pass through the top single-layer ceramic dielectric 21, while the third slot 23 passes through the bottom single-layer ceramic dielectric 21. The first slot 231 is located in the middle and upper part of the second slot, while the third slot 233 is located in the middle and lower part of the second slot 232. The interior of the second slot 232 is physically separated by the single-layer ceramic dielectric 21 to form an upper and lower area to achieve the airtight characteristics of the packaging structure. The single-layer ceramic dielectric 21 has a metal trace and is connected to the metal trace on the ceramic window step 222. The single-layer ceramic dielectric 21 and the metal trace form a probe structure 24 for the transition of the RF signal from the microstrip to the waveguide.

[0037] The first slot 231 and the third slot 233 are mainly used to form a waveguide cavity to reduce the dielectric loss of the radio frequency signal. The second slot 232 is mainly used for the radio frequency matching probe structure 24 to transmit the radio frequency signal with low loss.

[0038] The metal vias are divided into first metal vias 234, second metal vias 235, and third metal vias 236. These vias are primarily used to provide electromagnetic shielding. First metal vias 234 are located on the four walls of the first slot 231. Second metal vias 235 are located on the four walls of the second slot 232. Third metal vias 236 are located on the four walls of the third slot 233.

[0039] The first metal via 234 and the first slot 231 together form a waveguide-like structure and a short-circuit branch of the ceramic waveguide transition structure 23 . The ceramic waveguide short-circuit surface 237 of the short-circuit branch provides a necessary radio frequency reflection surface for the ceramic waveguide transition structure 23 .

[0040] The third metal via 236 and the third slot 233 together form a waveguide-like structure, providing a necessary transmission path for the radio frequency signal.

[0041] The second metal via 235 and the second slot 232 form a matching structure, which matches the probe structure 24 in the ceramic waveguide transition structure 23 to form a waveguide transition structure with good RF performance, and transition the RF signal from the microstrip with low loss to the waveguide.

[0042] The single-layer ceramic medium 21 where the probe structure 24 is located fully covers the second slot 232 , so that the ceramic waveguide transition structure 23 achieves airtightness.

[0043] The metal pads 4 are located at the opening of the third slot 233 of the ceramic waveguide transition structure 23 and are arranged in a rectangular circle around the outer side of the third slot 233. The HTCC airtight waveguide packaging structure is interconnected with external components at the metal pads 4 through methods such as ball implantation.

[0044] The RF signal of the present invention is input from any waveguide-like structure (third slot 233) in the HTCC airtight waveguide package. Passing through the second slot 232, the matching cavity and probe structure 24 work together to transform the RF signal from a waveguide mode to a microstrip quasi-TEM mode, where it is transmitted within the microstrip. The signal is then transmitted through the gold wire 32 to the RF microstrip 31 in the RF layer 3. Finally, the signal is output from the other end via the opposing gold wire 32, the probe structure 24, and the waveguide-like structure.

[0045] Example like Figure 8 、 Figure 9 As shown, the composite board 5 is made of a high-frequency microwave board and FR4 using a PCB process. A metal PAD is provided on the composite board 5, and the metal PAD and the metal pad 4 of the HTCC airtight waveguide packaging structure are interconnected through metal balls.

[0046] Among existing patents, CN115166641A, "A Miniaturized Surface-Mounted Transceiver Component Based on SIP," integrates the transmit and receive channels within a small HTCC package. This patent uses connectors to achieve airtightness and is not suitable for ultra-high frequency or terahertz frequency millimeter wave modules.

[0047] CN219998459U, "A V-band Airtight Waveguide Conversion Structure," achieves airtightness by sealing an insulator to a welded base. This patent also uses insulators to achieve airtightness, but requires a welded base to secure the insulator, increasing assembly complexity.

[0048] CN105527612A, "A T / R Module Sealing Structure," utilizes an airtight waveguide window, welding a flexible substrate into a corresponding groove. This achieves airtightness through the flexible substrate itself and the welding process. This patent requires secondary welding of the airtight waveguide window, which increases the number of assembly steps and hinders integrated processing.

[0049] The present invention introduces a waveguide structure into the HTCC package and can achieve airtightness.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A HTCC airtight waveguide packaging structure, characterized in that , including a ceramic cover plate, a multilayer ceramic dielectric, a radio frequency layer, and a metal pad; The ceramic cover is sealed and welded on the multilayer ceramic dielectric. The multilayer ceramic dielectric has a ceramic window structure and a ceramic waveguide transition structure. The ceramic window structure is arranged inside the multilayer ceramic dielectric to form a cavity structure. The ceramic window structure is located in the middle of the multilayer ceramic dielectric, and the two ceramic waveguide transition structures are respectively located at both ends of the ceramic window structure. The ceramic window structure comprises a bottom ceramic dielectric and a ceramic window step located on the bottom ceramic dielectric. The radio frequency layer is assembled on the bottom ceramic dielectric of the ceramic window structure. The radio frequency layer comprises a radio frequency microstrip and a gold wire connected to the radio frequency microstrip. Metal traces are arranged on the ceramic window step, and the metal traces are interconnected with the radio frequency microstrip via the gold wire. The ceramic waveguide transition structure consists of slots, metal vias, and metal traces inside a multilayer ceramic dielectric. The slots are divided into first, second, and third slots. The first slot does not pass through the top single-layer ceramic dielectric, while the third slot passes through the bottom single-layer ceramic dielectric. The interior of the second slot is physically separated by a single-layer ceramic dielectric to form an upper and lower area. The single-layer ceramic dielectric has a metal trace and is connected to the metal trace on the ceramic window step. The single-layer ceramic dielectric and the metal trace form a probe structure. The metal vias are divided into first metal vias, second metal vias, and third metal vias. The first metal vias are located on the four groove walls of the first slot, the second metal vias are located on the four groove walls of the second slot, and the third metal vias are located on the four groove walls of the third slot. The first metal vias and the first slot together form a waveguide-like structure and a short-circuit branch of the ceramic waveguide transition structure. The ceramic waveguide short-circuit surface of the short-circuit branch provides the necessary radio frequency reflection surface for the ceramic waveguide transition structure. The third metal vias and the third slot together form a waveguide-like structure, providing the necessary transmission path for the radio frequency signal. The second metal via and the second slot form a closed cavity structure, which matches the probe structure in the ceramic waveguide transition structure to form a waveguide transition structure with good RF performance, and transitions the RF signal from the microstrip with low loss to the waveguide. The metal pad is located at the opening of the third slot of the ceramic waveguide transition structure and is arranged in a circle along the outer side of the third slot in a rectangular manner. The HTCC airtight waveguide packaging structure is interconnected with external components at the metal pad by ball planting.

2. The HTCC airtight waveguide packaging structure according to claim 1, characterized in that: The ceramic cover plate is sealed and welded on the ceramic window structure in the middle.

3. The HTCC airtight waveguide packaging structure according to claim 1, wherein: The ceramic cover adopts HTCC technology and is a single-layer ceramic medium.

4. The HTCC airtight waveguide packaging structure according to claim 1, wherein: Multilayer ceramic dielectrics are made of multiple single-layer ceramic dielectrics sintered through the HTCC process.

5. The HTCC airtight waveguide packaging structure according to claim 1, wherein: The first slot is located in the middle and upper side of the second slot, and the third slot is located in the middle and lower side of the second slot.

6. The HTCC airtight waveguide packaging structure according to claim 1, wherein: The single-layer ceramic medium where the probe structure is located fully covers the second slot, so that the ceramic waveguide transition structure achieves airtightness.

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