Vertical mutual-connection axial transmission structure based on ceramic substrate and preparation method of vertical mutual-connection axial transmission structure
By designing a vertical interconnect coaxial transmission structure on a ceramic substrate, it solves the problem that traditional interconnect structures are difficult to meet the performance requirements of high-frequency and high-density integrated circuit applications, and achieves efficient vertical signal transmission and stability improvement.
Patent Information
- Application Number
- CN202510155876.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-12
- Publication Date
- 2025-05-06
AI Technical Summary
In high-frequency and high-density integrated circuit applications, traditional interconnect structures are difficult to meet performance requirements, especially to achieve efficient vertical interconnection on ceramic substrates.
A vertical interconnected coaxial transmission structure based on ceramic substrate is designed, including ceramic substrate, dielectric substrate, BCB substrate, coaxial metal column, dielectric layer and outer metal layer. Through these components, the vertical interconnection of the coplanar waveguide transmission line and the microstrip transmission line is realized, and metallic connection with the coplanar waveguide through BGA to form an integral electrical interconnection.
It realizes efficient vertical signal transmission, reduces signal loss and reflection, improves the stability and reliability of signal transmission, and is suitable for high-density integrated packaging applications.
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Figure CN119944265A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of three-dimensional integrated packaging, and in particular to a vertical interconnection coaxial transmission structure based on a ceramic substrate and a preparation method thereof. Background Art
[0002] With the continuous development of integrated circuit technology, the requirements for packaging technology are becoming higher and higher; especially in high-frequency and high-density integrated circuit applications, traditional interconnect structures have been difficult to meet performance requirements; ceramic substrates, as a high-performance packaging material, have good mechanical properties, thermal properties and electrical properties. Some ceramic materials in ceramic through-holes have high resistivity. The method of filling ceramic through-holes with slurry has a simple process, complete filling, strong adhesion, and low cost. The dry process can eliminate copper plating chemical residues, and all holes can be filled by printing, with high process efficiency.
[0003] Since the ceramic material itself is relatively brittle when designing ceramic through holes, it is difficult to process the through holes on the substrate. Considering the limitation of the aspect ratio of the through holes, the ceramic through holes must not be less than a certain size during the process. In this case, the signal transmission interconnection length on the ceramic substrate is long, which increases the interconnection loss and the process difficulty. How to achieve efficient vertical interconnection on ceramic substrates remains a technical challenge. Summary of the invention
[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a vertical interconnection coaxial transmission structure based on a ceramic substrate and a preparation method thereof to solve the technical problems mentioned in the above-mentioned background technology.
[0005] To achieve the above purpose, the technical solution adopted by the present invention is: In a first aspect, a vertically interconnected coaxial transmission structure based on a ceramic substrate is provided, which includes a ceramic substrate and a dielectric substrate and a BCB substrate respectively arranged on the top and bottom of the ceramic substrate, a coplanar waveguide transmission line is arranged on the top surface of the BCB substrate, a microstrip transmission line is arranged on the top surface of the dielectric substrate, and a coaxial transmission structure for realizing vertical interconnection between the coplanar waveguide transmission line and the microstrip transmission line is embedded in the middle of the ceramic substrate; the coaxial transmission structure includes a coaxial metal column, a dielectric layer sleeved on the outside of the coaxial metal column, and an outer metal layer sleeved on the outside of the dielectric layer, the bottom of the coaxial metal column is connected to the coplanar waveguide transmission line through a BGA, the top of the coaxial metal column is connected to the vertical metal column in the dielectric substrate, the vertical metal column is connected to the microstrip transmission line, a microstrip line metal ground is arranged on the bottom surface of the dielectric substrate, a coplanar waveguide metal ground is arranged on the top surface of the BCB substrate, and the top and bottom of the outer metal layer are respectively connected to the microstrip line metal ground and the coplanar waveguide metal ground.
[0006] Furthermore, the bottom of the outer metal layer is connected to the coplanar waveguide metal ground through a plurality of BGAs, and the plurality of BGAs are evenly spaced and arranged in a circumferential direction of the bottom of the outer metal layer.
[0007] Furthermore, a plurality of BGAs are respectively connected to the coaxial metal pillars and the outer metal layer through a plurality of pads.
[0008] Furthermore, the microstrip line metal ground is located around the top of the outer metal layer.
[0009] Furthermore, the matching impedances of the coplanar waveguide transmission line, the microstrip transmission line and the coaxial transmission structure are all 50Ω.
[0010] Furthermore, both the coplanar waveguide transmission line and the microstrip transmission line are preset with interfaces for connecting to the test equipment.
[0011] Furthermore, an access end of the coplanar waveguide transmission line protrudes from one side of the ceramic substrate.
[0012] In a second aspect, a method for preparing a vertical interconnection coaxial transmission structure based on a ceramic substrate is provided, which comprises the following steps: S1: punching a ceramic substrate, filling the hole with metal, and performing secondary punching on the metal column formed by the filling, wherein the aperture of the secondary punching is smaller than the diameter of the metal column, and an outer metal layer is formed in the hole of the ceramic substrate; S2: filling the outer metal layer with dielectric, punching the dielectric column formed by the filling to form a dielectric layer; and filling the hole with metal to form a coaxial metal column; S3: soldering pads at the bottom of the coaxial metal column, the bottom of the pads are connected to the coplanar waveguide transmission line on the BCB substrate through BGA, forming a vertical interconnection between the coplanar waveguide transmission line and the coaxial metal column; at the same time, soldering a number of pads at preset points on the circumference of the bottom of the outer metal layer, and the bottoms of the several pads are connected to the coplanar waveguide metal ground through a number of BGAs; S4: Connect the top of the coaxial metal column to the bottom of the vertical metal column in the dielectric substrate, and connect the top of the vertical metal column to the microstrip transmission line on the dielectric substrate to form a vertical interconnection between the coaxial metal column and the microstrip transmission line; at the same time, connect the microstrip line metal ground around the outer metal layer to form an overall electrical interconnection.
[0013] Further, the top and bottom of the BGA are flattened until the height of the BGA is 70% of its diameter.
[0014] The beneficial effects of the present invention are: 1. This scheme realizes efficient vertical signal transmission by designing a coaxial transmission structure with vertical interconnection on a ceramic substrate. The dielectric layer and the coaxial metal column in the coaxial transmission structure jointly determine the characteristic impedance of the structure. By designing the size of the coaxial transmission structure, the overall impedance matching can be achieved, which can reduce signal loss and reflection; the outer metal layer of the coaxial structure can not only suppress electromagnetic interference, but also reduce the reflection of the signal during transmission, absorb and reflect part of the signal incident on the via port, thereby reducing the reflection and standing wave effect of the signal inside the via; this shielding effect helps to improve the stability and reliability of signal transmission and further reduce signal reflection.
[0015] 2. The BGA of this solution can play a good role in signal reflection and can make the signal transmission smooth at high frequency. The entire vertical transmission structure is a "Z"-shaped vertical interconnection structure, which can minimize the length of the interconnection line, so that the overall has excellent electrical characteristics such as ultra-high operating frequency, ultra-wide operating frequency band, and ultra-low insertion loss, ensuring the integrity and transmission efficiency of the signal; and by optimizing the size and material selection, this solution is suitable for high-density integrated packaging applications.
[0016] 3. The method for preparing the vertical interconnected coaxial transmission structure based on the ceramic substrate in this scheme has a simple process and is easy to process. It is compatible with the existing ceramic substrate packaging process and can be easily integrated into the existing production process for mass production. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a schematic diagram of the three-dimensional structure of this scheme.
[0018] Figure 2 This is a schematic diagram of the top view structure of this scheme.
[0019] Figure 3 This is a schematic diagram of the front view structure of this scheme.
[0020] Figure 4 This is a side structural schematic diagram of this scheme.
[0021] Figure 5 This is a flow chart of the preparation method of this scheme.
[0022] Among them, 1-microstrip transmission line; 2-vertical metal column; 3-coplanar waveguide transmission line; 4-outer metal layer; 5-dielectric layer; 6-BGA; 7-soldering pad; 8-coaxial metal column; 9-dielectric substrate; 10-BCB substrate; 11-microstrip line metal ground; 12-ceramic substrate; 13-coplanar waveguide metal ground. DETAILED DESCRIPTION
[0023] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.
[0024] like Figures 1 to 4 As shown, the vertical interconnection coaxial transmission structure based on the ceramic substrate of the present scheme includes a ceramic substrate 12 and a dielectric substrate 9 and a BCB substrate 10 respectively arranged on the top and bottom of the ceramic substrate 12, wherein the ceramic substrate 12 has a simple process, good stability, and still has good current carrying capacity at high frequencies, and the BCB substrate 10 has excellent flatness; a coplanar waveguide transmission line 3 is arranged on the top surface of the BCB substrate 10 for signal transmission and impedance matching, and has good electromagnetic compatibility on the BCB substrate 10; a microstrip transmission line 1 is arranged on the top surface of the dielectric substrate 9 for signal transmission and impedance matching; a coaxial transmission structure for realizing vertical interconnection between the coplanar waveguide transmission line 3 and the microstrip transmission line 1 is embedded in the middle of the ceramic substrate 12; the coaxial transmission structure includes a coaxial metal column 8, a dielectric layer 5 sleeved on the outside of the coaxial metal column 8, and an outer metal layer 4 sleeved on the outside of the dielectric layer 5, wherein the coaxial metal column 8 and the dielectric Layer 5 can determine the characteristic impedance of the coaxial structure and maintain the stability of the structure. The outer metal layer 4 can suppress signal interference and serve as a stable signal reference ground. The bottom of the coaxial metal column 8 is connected to the coplanar waveguide transmission line 3 through BGA6. BGA6 can reduce the length of the interconnection line, play a good signal reflection role and make the signal transmission stable at high frequency. The top of the coaxial metal column 8 is connected to the vertical metal column 2 in the dielectric substrate 9, and the vertical metal column 2 is connected to the microstrip transmission line 1. A microstrip line metal ground 11 is provided on the bottom surface of the dielectric substrate 9, and a coplanar waveguide metal ground 13 is provided on the top and bottom surfaces of the BCB substrate 10. The top and bottom of the outer metal layer 4 are respectively connected to the microstrip line metal ground 11 and the coplanar waveguide metal ground 13; wherein, the microstrip line metal ground 11 can realize the grounding of the coaxial transmission structure and the microstrip transmission line 1, and the coplanar waveguide metal ground 13 can realize the grounding of the coaxial transmission structure and the coplanar waveguide transmission line 3.
[0025] The coplanar waveguide transmission line 3 of this solution is vertically interconnected with the coaxial metal column 8 in the coaxial transmission structure through BGA6 and pad 7, and the coaxial metal column 8 is vertically interconnected with the microstrip transmission line 1 through the vertical metal column 2 in the dielectric substrate 9, forming a complete signal transmission link.
[0026] As an optional embodiment, the microstrip line metal ground 11 is located around the top of the outer metal layer 4, and the bottom of the outer metal layer 4 is connected to the coplanar waveguide metal ground 13 through several BGA6 to form an electrical interconnection; wherein, several BGA6 can be evenly spaced in the circumferential direction of the bottom of the outer metal layer 4.
[0027] As an optional implementation, a plurality of BGAs 6 are respectively connected to the coaxial metal pillars 8 and the outer metal layer 4 through a plurality of pads 7 to achieve interconnection between the coaxial transmission structure and the BGA 6 and enhance the stability of the structure.
[0028] As an optional implementation, the sizes of the coplanar waveguide transmission line 3, the microstrip transmission line 1 and the coaxial transmission structure and the corresponding substrates are optimized respectively to meet the 50Ω impedance matching standard.
[0029] As an optional implementation, the lengths of the coplanar waveguide transmission line 3 and the microstrip transmission line 1 are shortened as much as possible while satisfying the corresponding substrate length restrictions, thereby facilitating reduction in the size of the interconnection line; the access end of the coplanar waveguide transmission line 3 protrudes from one side of the ceramic substrate 12, that is, the length of the BCB substrate 10 in the extension direction of the coplanar waveguide transmission line 3 is longer than the lengths of the ceramic substrate 12 and the dielectric substrate 9 above it, so that the coplanar waveguide transmission line 3 can be effectively connected to the test equipment. At the same time, both the coplanar waveguide transmission line 3 and the microstrip transmission line 1 are pre-set with interfaces for connecting to the test equipment.
[0030] like Figure 5 As shown, the present solution also provides a method for preparing a vertical interconnection coaxial transmission structure based on a ceramic substrate 12, which comprises the following steps: S1: punching the ceramic substrate 12, filling the holes with metal, and performing secondary punching on the metal pillars formed by the filling, wherein the aperture of the secondary punching is smaller than the diameter of the metal pillars, and an outer metal layer 4 is formed in the holes of the ceramic substrate 12; S2: filling the outer metal layer 4 with dielectric, punching the dielectric column formed by the filling to form a dielectric layer 5; and filling the hole with metal to form a coaxial metal column 8; S3: soldering pad 7 at the bottom of coaxial metal column 8, the bottom of soldering pad 7 is connected to coplanar waveguide transmission line 3 on BCB substrate 10 through BGA 6, so as to form vertical interconnection between coplanar waveguide transmission line 3 and coaxial metal column 8; at the same time, soldering several soldering pads 7 at preset points on the circumferential direction of the bottom of outer metal layer 4, respectively, the bottoms of several soldering pads 7 are connected to coplanar waveguide metal ground 13 through several BGA 6 respectively; S4: Connect the top of the coaxial metal column 8 to the bottom of the vertical metal column 2 in the dielectric substrate 9, and connect the top of the vertical metal column 2 to the microstrip transmission line 1 on the dielectric substrate 9 to form a vertical interconnection between the coaxial metal column 8 and the microstrip transmission line 1; at the same time, connect the microstrip line metal ground 11 around the outer metal layer 4 to form an overall electrical interconnection.
[0031] As an optional embodiment, the top and bottom of the BGA 6 are flattened until the height of the BGA 6 is 70% of its diameter.
[0032] In summary, this scheme realizes efficient vertical signal transmission by designing a coaxial transmission structure for vertical interconnection on a ceramic substrate 12. The dielectric layer 5 and the coaxial metal column 8 in the coaxial transmission structure jointly determine the characteristic impedance of the structure. By designing the size of the coaxial transmission structure, the overall impedance matching can be achieved, which can reduce signal loss and reflection; the outer metal layer 4 of the coaxial structure can not only suppress electromagnetic interference, but also reduce the reflection of the signal during transmission, absorb and reflect part of the signal incident on the via port, thereby reducing the reflection and standing wave effect of the signal inside the via; this shielding effect helps to improve the stability and reliability of signal transmission and further reduce signal reflection; the BGA6 of this scheme can play a good signal reflection role and can make the signal transmission stable at high frequency. The entire vertical transmission structure is a "Z"-shaped vertical interconnection structure, which can minimize the length of the interconnection line, so that the overall has excellent electrical characteristics such as ultra-high operating frequency, ultra-wide operating frequency band, and ultra-low insertion loss, ensuring the integrity and transmission efficiency of the signal; and by optimizing the size and material selection, the scheme is suitable for high-density integrated packaging applications.
Claims
1. A vertical interconnection coaxial transmission structure based on a ceramic substrate, characterized in that: It comprises a ceramic substrate and a dielectric substrate and a BCB substrate respectively arranged on the top and bottom of the ceramic substrate, wherein a coplanar waveguide transmission line is arranged on the top surface of the BCB substrate, a microstrip transmission line is arranged on the top surface of the dielectric substrate, and a coaxial transmission structure for realizing vertical interconnection between the coplanar waveguide transmission line and the microstrip transmission line is embedded in the middle of the ceramic substrate; The coaxial transmission structure includes a coaxial metal column, a dielectric layer sleeved on the outside of the coaxial metal column, and an outer metal layer sleeved on the outside of the dielectric layer. The bottom of the coaxial metal column is connected to the coplanar waveguide transmission line through BGA, the top of the coaxial metal column is connected to the vertical metal column in the dielectric substrate, the vertical metal column is connected to the microstrip transmission line, a microstrip line metal ground is arranged on the bottom surface of the dielectric substrate, a coplanar waveguide metal ground is arranged on the top surface of the BCB substrate, and the top and bottom of the outer metal layer are respectively connected to the microstrip line metal ground and the coplanar waveguide metal ground.
2. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 1, characterized in that: The bottom of the outer metal layer is connected to the coplanar waveguide metal ground through a plurality of BGAs, and the plurality of BGAs are evenly spaced and arranged in a circumferential direction of the bottom of the outer metal layer.
3. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 2, characterized in that: A plurality of BGAs are respectively connected to the coaxial metal pillars and the outer metal layer through a plurality of pads.
4. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 1, characterized in that: The microstrip line metal ground is located around the top of the outer metal layer.
5. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 1, characterized in that: The matching impedances of the coplanar waveguide transmission line, microstrip transmission line and coaxial transmission structure are all 50Ω.
6. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 1, characterized in that: The coplanar waveguide transmission line and the microstrip transmission line are both preset with interfaces for connecting with test equipment.
7. The vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 1, characterized in that: The access end of the coplanar waveguide transmission line protrudes from one side of the ceramic substrate.
8. The method for preparing a vertical interconnection coaxial transmission structure based on a ceramic substrate according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: punching a ceramic substrate, filling the hole with metal, and performing secondary punching on the metal column formed by the filling, wherein the aperture of the secondary punching is smaller than the diameter of the metal column, and an outer metal layer is formed in the hole of the ceramic substrate; S2: filling the outer metal layer with dielectric, punching the dielectric column formed by the filling to form a dielectric layer; and filling the hole with metal to form a coaxial metal column; S3: soldering pads at the bottom of the coaxial metal column, the bottom of the pads are connected to the coplanar waveguide transmission line on the BCB substrate through BGA, forming a vertical interconnection between the coplanar waveguide transmission line and the coaxial metal column; at the same time, soldering a number of pads at preset points on the circumference of the bottom of the outer metal layer, and the bottoms of the several pads are connected to the coplanar waveguide metal ground through a number of BGAs; S4: Connect the top of the coaxial metal column to the bottom of the vertical metal column in the dielectric substrate, and connect the top of the vertical metal column to the microstrip transmission line on the dielectric substrate to form a vertical interconnection between the coaxial metal column and the microstrip transmission line; at the same time, connect the microstrip line metal ground around the outer metal layer to form an overall electrical interconnection.
9. The method for preparing a vertical interconnection coaxial transmission structure based on a ceramic substrate according to claim 8, characterized in that: Flatten the top and bottom of the BGA until the height of the BGA is 70% of its diameter.