Microwave and millimeter wave compact RF digital integrated front-end module

Abstract

The present invention discloses a microwave millimeter wave low-cost compact radio frequency digital integrated front-end module, which relates to the field of microwave millimeter wave device technology. The front-end module includes a substrate layer, the upper surface of which is respectively provided with a precursor compound bare chip and a silicon-based chip group, a first group of BGA solder balls located on the lower surface of the substrate layer is connected to a first metal pad on one side of the precursor compound bare chip via a first type of coaxial structure that penetrates the substrate layer from top to bottom, a second metal pad is connected to a BGA solder ball on one side of the BGA packaged chip via a second type of coaxial structure that penetrates the substrate layer from top to bottom, the BGA packaged chip is connected to a third metal pad on one side of the silicon-based chip group via a third type of coaxial structure that penetrates the substrate layer from top to bottom, and a fourth metal pad is connected to a second group of BGA solder balls located on the lower surface of the substrate layer via a fourth type of coaxial structure that penetrates the substrate layer from top to bottom. The front-end module can achieve extremely low-loss transmission and has greater interconnection flexibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave and millimeter wave devices, and in particular relates to a microwave and millimeter wave compact radio frequency digital integrated front-end module. Background Art

[0002] The ceramic DPC (Dielectric Polymer Composite) film process is an advanced technology that combines the advantages of ceramic and polymer materials. It is used to prepare system modules that require a low dielectric constant and excellent mechanical properties. The low dielectric constant of the dielectric PI effectively enhances the uniform distribution of the electric field and reduces the phenomenon of excessive local electric field concentration, thereby improving the stability of the film under high voltage. The ceramic material itself has good thermal stability, and the polymer in the composite material provides a certain thermal buffering effect, allowing the DPC film to maintain excellent electrical and mechanical properties at higher temperatures. Its high reliability and compact design advantages make it commonly used in the design of modules such as antennas, RF, and passive components.

[0003] The surface of DPC substrates can be formed into a variety of highly controllable metallization patterns through localized sputtering, providing new ideas and solutions for microwave RF design. The integration of millimeter-wave RF front-ends is key to modern wireless communications (such as 5G / 6G) and radar systems, but it still faces some significant technical challenges and shortcomings.

[0004] 1) High-frequency loss: At millimeter-wave frequencies, material losses in conductors, dielectrics, and interconnects increase significantly. Transmission line losses are high, especially over long distances. Parasitic and coupling effects are more pronounced in high-frequency circuits, leading to performance degradation. Impact: This reduces power amplifier efficiency, negatively impacting overall system performance (such as gain and sensitivity).

[0005] 2) Heat dissipation: Millimeter-wave front-end integrated circuits have high power density and limited thermal conductivity, making heat dissipation design challenging. Impact: Rising temperatures can affect device performance stability, particularly the power amplifier (PA) and low-noise amplifier (LNA). Inadequate thermal management can lead to device failure or shortened lifespan.

[0006] 3) Complex and expensive manufacturing processes: Millimeter-wave frequencies place extremely high demands on manufacturing processes, requiring high-precision process technologies (such as CMOS, GaAs, GaN, and SiGe). Antennas, transmission lines, and filters are smaller in the millimeter-wave frequency band, requiring even higher manufacturing precision. Process nonuniformity can lead to performance variations. Impact: Integrated manufacturing costs are high, especially in large-scale production. Process errors can lead to performance deviations or even circuit failure.

[0007] 4) Layout and Design Difficulty: The design of the millimeter-wave RF front-end must simultaneously meet multiple requirements, including high-frequency signal transmission, thermal management, and interconnect density. High-frequency signals are susceptible to interference, requiring special design measures to reduce parasitic effects and signal coupling. The extremely small device size and circuit spacing increase design complexity. Impact: Long design cycles and limited product iteration speed. Signal integrity and electromagnetic compatibility issues are easily introduced during the design.

[0008] 5) Power consumption and efficiency: Amplifiers and mixers in the millimeter-wave band have low efficiency. The low efficiency of the power amplifier leads to high overall power consumption. This creates a conflict between the need for low-power design and the demand for high performance. Impact: This limits the battery life of battery-powered devices (such as mobile terminals). High power consumption places higher demands on heat dissipation design.

[0009] 6) Electromagnetic Interference and Shielding Issues: Millimeter-wave signals have very short wavelengths and are prone to electromagnetic interference (EMI), especially in high-density integrated environments. Electromagnetic coupling and intermodulation between devices are more pronounced. Impact: Reduced system signal integrity and increased shielding design complexity and cost. Summary of the Invention

[0010] The technical problem to be solved by the present invention is how to provide a radio frequency digital integrated front-end module that can achieve extremely low-loss transmission and has greater interconnection flexibility.

[0011] To solve the above technical problems, the technical solution adopted by the present invention is: a microwave and millimeter wave compact radio frequency digital integrated front-end module, including a substrate layer, the upper surface of which is respectively provided with a precursor compound bare chip and a silicon-based chipset, the outer covers of the precursor compound bare chip and the silicon-based chipset are provided with an airtight isolation frame and a cover plate, the lower surface of the substrate layer between the precursor compound bare chip and the silicon-based chipset is formed with a BGA packaged chip, a first group of BGA solder balls located on the lower surface of the substrate layer is connected to a first metal pad on one side of the precursor compound bare chip via a first type of coaxial structure that penetrates the substrate layer from top to bottom, and a second metal pad is formed on the upper surface of the substrate layer on the other side of the precursor compound bare chip. The second metal pad is connected to the BGA solder ball on one side of the BGA packaged chip via a second type of coaxial structure that penetrates the substrate layer from top to bottom, and the BGA solder ball on the other side of the BGA packaged chip is connected to the third metal pad on one side of the silicon-based chip group via a third type of coaxial structure that penetrates the substrate layer from top to bottom. A fourth metal pad is formed on the upper surface of the substrate layer on the other side of the silicon-based chip group, and the fourth metal pad is connected to the second group of BGA solder balls located on the lower surface of the substrate layer via the fourth type of coaxial structure that penetrates the substrate layer from top to bottom. The precursor compound bare chip and the first and second metal pads, as well as the silicon-based chip group and the third and fourth metal pads are connected by gold bonding wires.

[0012] The beneficial effects of adopting the above technical solution are as follows: the front-end module includes a pre-stage compound bare chip, a silicon-based chipset, and a BGA packaged chip, using a back-to-back structure to achieve low-loss point-to-point interconnection of RF signals and a compact module design; the excellent thermal conductivity of the DPC substrate can effectively dissipate heat from the chip, and advanced thin-film processing is used to achieve high-density RDL of the silicon-based chip; the placement of the front and back of the chip can simultaneously ensure electromagnetic compatibility between the front-side amplifier bare chips in different channels, and the airtightness of the bare chip can be guaranteed by the sealing cover. The DPC substrate processing can achieve local thick copper to realize the metal pad design integrated with the substrate, making various interconnections more flexible and eliminating the need for additional assembly processes.

[0013] In this application, BGA solder balls are used as part of the connection between the chip and the substrate. BGA transmission can achieve low-loss and low-cost board-to-board interconnection within the wide frequency band of microwave and millimeter waves. The interconnection method of bare die bonding (connected to metal pads via gold wire bonding wires) realizes millimeter wave transmission. By using the metal pads of the DPC substrate itself to compensate for the bonding height, the signal path adopts the shortest transmission path of BGA-coaxial-metal pads-bonding wires, which can achieve extremely low-loss transmission effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic cross-sectional structural diagram of the front-end module according to an embodiment of the present invention;

[0015] Figure 2 is a schematic structural diagram of the connection between the front-end module and the motherboard according to an embodiment of the present invention;

[0016] Figure 3 2 is a simulation result diagram in an embodiment of the present invention;

[0017] Among them: 1. Pre-stage compound bare chip; 2. Silicon-based chipset; 2-1. Silicon-based chip module; 2-1-1. Carrier; 2-1-2. Silicon-based chip; 3. Isolation frame; 4. Cover; 5. BGA packaged chip; 6. First group of BGA solder balls; 7. First type coaxial structure; 8. First metal pad; 9. Second metal pad; 10. Second type coaxial structure; 11. Third type coaxial structure; 12. Third metal pad; 13. Fourth metal pad; 14. Fourth type coaxial structure; 15. Second group of BGA solder balls; 16. Gold bonding wire; 17. First substrate metal layer; 18. First substrate film layer; 19. Second substrate metal layer; 20. Second substrate film layer; 21. Third substrate metal layer; 22. First substrate core layer; 23. Fourth substrate metal layer; 24. First metallized via; 25. Second metallized via; 26. Motherboard. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] like Figure 1 As shown, an embodiment of the present invention discloses a microwave-millimeter-wave compact RF-digital integrated front-end module, comprising a substrate layer, which comprises, from bottom to top, a first substrate metal layer 17, a first substrate film layer 18, a second substrate metal layer 19, a second substrate film layer 20, a third substrate metal layer 21, a first substrate core layer 22, and a fourth substrate metal layer 23. Preferably, the first substrate core layer 22 is made of a DPC ceramic dielectric. The use of DPC ceramic dielectric can effectively improve the thermal conductivity of the front-end compound bare die 1, allowing the heat of the entire module to be effectively transferred to the substrate BGA solder balls.

[0021] As the core layer of the basic layer, Figure 1 It can be seen that the thickness of the first substrate core layer 22 is greater than the thickness of the first substrate metal layer 17, the first substrate film layer 18, the second substrate metal layer 19, the second substrate film layer 20, the third substrate metal layer 21, and the fourth substrate metal layer 23. The thicknesses of the first substrate metal layer 17 to the fourth substrate metal layer 23 are the same, and the thicknesses of the first substrate film layer 18 and the second substrate film layer 20 are the same.

[0022] like Figure 1As shown, the upper surface of the fourth substrate metal layer 23 is provided with a precursor compound bare chip 1 and a silicon-based chipset 2, respectively. The outer covers of the precursor compound bare chip 1 and the silicon-based chipset 2 are provided with an airtight isolation frame 3 and a cover plate 4. These isolation frame 3 and cover plate 4 isolate the upper surface of the substrate layer into two areas: one area is used to seal the precursor compound bare chip 1 and its associated first and second metal pads 8 and 9, and the other area is used to seal the silicon-based chipset 2 and its associated third and fourth metal pads 12 and 13. The airtight isolation frame 3 and cover plate 4 ensure electromagnetic isolation and airtightness between the precursor compound bare chip 1 and the silicon-based chipset 2 above the substrate core layer and the chipset formed by the substrate layer, thereby improving the reliability of the overall design.

[0023] Further, such as Figure 1 As shown, a BGA packaged chip 5 is formed on the lower surface of the first substrate metal layer 17 between the precursor compound bare chip 1 and the silicon-based chip group 2. A first group of BGA solder balls 6 located on the lower surface of the substrate layer are connected to a first metal pad 8 on the upper surface of the fourth substrate metal layer 23 on one side of the precursor compound bare chip 1 via a first type coaxial structure 7 that penetrates the substrate layer from top to bottom. A second metal pad 9 is formed on the upper surface of the fourth substrate metal layer 23 on the other side of the precursor compound bare chip 1. The second metal pad 9 is connected to a BGA solder ball on one side of the BGA packaged chip 5 via a second type coaxial structure 10 that penetrates the substrate layer from top to bottom. The BGA packaged chip 5 on the back can be electromagnetically isolated by a surrounding structure composed of surrounding BGA solder balls.

[0024] The BGA solder balls on the other side of the BGA packaged chip 5 are connected to third metal pads 12 on the upper surface of the fourth substrate metal layer 23 on one side of the silicon-based chipset 2 via a third coaxial structure 11 that extends upward and downward through the substrate layer. A fourth metal pad 13 is formed on the upper surface of the fourth substrate metal layer 23 on the other side of the silicon-based chipset 2. These fourth metal pads 13 are connected to a second group of BGA solder balls 15 located on the lower surface of the first substrate metal layer 17 via a fourth coaxial structure 14 that extends upward and downward through the substrate layer. Gold bonding wires 16 connect the precursor compound bare chip 1 to the first and second metal pads 8 and 9, as well as the silicon-based chipset 2 to the third and fourth metal pads 12 and 13.

[0025] Further, such as Figure 1As shown, the silicon-based chip group 2 includes two or more silicon-based chip modules 2-1 stacked in an upper and lower layer. The specific structures of the silicon-based chip modules 2-1 can be the same or different. In this application, two silicon-based chip modules 2-1 with the same structure are provided. Furthermore, the silicon-based chip module 2-1 includes a carrier board 2-1-1 and a silicon-based chip 2-1-2 located on the carrier board 2-1-1. The two silicon-based chip modules 2-1 are connected via BGA solder balls between the carrier boards 2-1-1. Figure 1 As shown, since there is one precursor compound bare chip 1 and the height of the upper surface of the precursor compound bare chip 1 remains basically the same, the height of the first metal pad 8 and the second metal pad 9 is basically the same as the height of the precursor compound bare chip 1; since the silicon-based chip group 2 adopts a plurality of silicon-based chip modules 2-1 for stacking structure setting, in order to connect the silicon-based chip module 2-1 located on the uppermost side, the height of the third metal pad 12 is basically the same as the height of the silicon-based chip group 2, and in order to connect the silicon-based chip module 2-1 located on the lowermost side, the height of the fourth metal pad 13 is basically the same as the height of the silicon-based chip module 2-1 located at the lowermost layer in the silicon-based chip group 2.

[0026] Further, such as Figure 1 As shown, the structures of the first type coaxial structure 7 to the fourth type coaxial structure 14 are the same, and all include a first metallized via 24, the upper end of the first metallized via 24 passes through the upper surface of the fourth substrate metal layer 23 and is connected to the metal pad, the lower end of the first metallized via 24 passes through the lower surface of the first substrate metal layer 17 and is connected to the BGA solder ball, and a plurality of second metallized vias 25 are arranged at intervals on the periphery of the first metallized via 24, the upper end of the second metallized via 25 extends to the lower surface of the fourth substrate metal layer 23, and the lower end of the second metallized via 25 extends to the upper surface of the first substrate metal layer 17. Furthermore, in order to stably connect the metal pad and the BGA solder ball, an upper connecting portion is formed at the upper end of the first metallized via 24, and the diameter of the upper connecting portion is larger than the diameter of the first metallized via body and is adapted to the metal pad; a lower connecting portion is formed at the lower end of the first metallized via 24, and the diameter of the lower connecting portion is larger than the diameter of the first metallized via body and is adapted to the BGA solder ball.

[0027] Signal transmission process: the high-frequency signal circuit adopts a quasi-coaxial structure for vertical transmission within the substrate, and its transmission frequency can reach 40GHz; the signal is input from the BGA solder balls used for signal transmission in the first group of BGA solder balls 6 at the bottom to the first type of coaxial structure 7 inside the substrate, and is transmitted to the front-end compound bare core 1 through the interlayer first type coaxial structure 7. After being processed by the front-end compound bare core 1, the signal is again transmitted vertically between layers through the second type of coaxial structure 10 to the BGA packaged chip 5; the digital signal passes through the pins of the BGA packaged chip 5 and through the third type of coaxial structure 11 inside the substrate and is bonded to the silicon-based chip group 2 through the third metal pad 12. After the three-dimensional stacked chipset is processed by the silicon-based chip group 2, it is electrically connected by bonding to the fourth metal pad 13, and finally transmitted to the second group of BGA solder balls on the bottom layer of the substrate through the fourth type of coaxial structure 14.

[0028] Further, such as Figure 2 As shown, the front-end module also includes a motherboard 26, which is connected to the BGA solder balls in the first group of BGA solder balls 6 for signal transmission through the microstrip lines on its PCB. In this application, the front-end module enters the first group of BGA solder balls 6 of the substrate through the microstrip lines on the PCB of the motherboard 26. The first group of BGA solder balls 6 transmit and feed power, and tap feeding is performed on the lower thin-film metal layer of the substrate. The first type of coaxial structure 7 is connected to the first metal pad 8, and then the first metal pad 8 is connected to the PAD on the front-end compound bare core 1 through the two ends of the gold wire bonding wire to achieve electrical connection. The entire front-end package uses two layers of PI dielectric and one layer of DPC ceramic dielectric.

[0029] Attachment Figure 3 This is a schematic diagram of the simulation results of the front-end module described in this application. It can be seen that the return loss in the 1-40GHz band is within the usable range, and the loss is also very small due to the short propagation path. Therefore, a low-cost and compact design of the front-stage compound die and BGA phased array chip is achieved without unnecessary winding.

Claims

1. A microwave and millimeter wave compact radio frequency digital integrated front-end module, characterized by: The invention comprises a substrate layer, wherein a precursor compound bare chip (1) and a silicon-based chip group (2) are respectively provided on the upper surface of the substrate layer, and the outer covers of the precursor compound bare chip (1) and the silicon-based chip group (2) are provided with an airtight isolation frame (3) and a cover plate (4), and a BGA package chip (5) is formed on the lower surface of the substrate layer between the precursor compound bare chip (1) and the silicon-based chip group (2), and a first group of BGA solder balls (6) located on the lower surface of the substrate layer is connected to a first metal pad (8) on one side of the precursor compound bare chip (1) through a first type of coaxial structure (7) penetrating the substrate layer from top to bottom, and a second metal pad (9) is formed on the upper surface of the substrate layer on the other side of the precursor compound bare chip (1), and the second metal pad (9) is connected to a second type of coaxial structure (10) penetrating the substrate layer from top to bottom. The BGA solder balls on one side of the BGA packaged chip (5) are connected, and the BGA solder balls on the other side of the BGA packaged chip (5) are connected to the third metal pad (12) on one side of the silicon-based chip group (2) via a third type of coaxial structure (11) that penetrates the substrate layer from top to bottom. A fourth metal pad (13) is formed on the upper surface of the substrate layer on the other side of the silicon-based chip group (2). The fourth metal pad (13) is connected to the second group of BGA solder balls (15) located on the lower surface of the substrate layer via a fourth type of coaxial structure (14) that penetrates the substrate layer from top to bottom. The front-stage compound bare chip (1) and the first metal pad (8) and the second metal pad (9), as well as the silicon-based chip group (2) and the third metal pad (12) and the fourth metal pad (13) are connected via gold wire bonding wires (16).

2. The microwave-millimeter-wave compact radio-frequency digital integrated front-end module according to claim 1, characterized in that: The substrate layer comprises, arranged from bottom to top, a first substrate metal layer (17), a first substrate film layer (18), a second substrate metal layer (19), a second substrate film layer (20), a third substrate metal layer (21), a first substrate core layer (22), and a fourth substrate metal layer (23).

3. The microwave-millimeter-wave compact radio-frequency digital integrated front-end module according to claim 2, characterized in that: The first substrate core layer (22) is made of DPC ceramic medium.

4. The microwave-millimeter-wave compact radio-frequency digital integrated front-end module according to claim 2, characterized in that: The thickness of the first substrate core layer (22) is greater than the thickness of the first substrate metal layer (17), the first substrate film layer (18), the second substrate metal layer (19), the second substrate film layer (20), the third substrate metal layer (21), and the fourth substrate metal layer (23).

5. The microwave-millimeter-wave compact radio frequency digital integrated front-end module according to claim 2, characterized in that: The structures of the first type coaxial structure (7) to the fourth type coaxial structure (14) are the same, including a first metallized via (24), the upper end of the first metallized via (24) passes through the upper surface of the fourth substrate metal layer (23) and is connected to the metal pad, the lower end of the first metallized via (24) passes through the lower surface of the first substrate metal layer (17) and is connected to the BGA solder ball, and a plurality of second metallized vias (25) are arranged at intervals on the periphery of the first metallized via (24), the upper end of the second metallized via (25) extends to the lower surface of the fourth substrate metal layer (23), and the lower end of the second metallized via (25) extends to the upper surface of the first substrate metal layer (17).

6. The microwave-millimeter-wave compact radio-frequency digital integrated front-end module according to claim 5, characterized in that: An upper connecting portion is formed at the upper end of the first metallized via (24), the diameter of the upper connecting portion is greater than the diameter of the first metallized via body, and is compatible with the metal pad; a lower connecting portion is formed at the lower end of the first metallized via (24), the diameter of the lower connecting portion is greater than the diameter of the first metallized via body, and is compatible with the BGA solder ball.

7. The microwave-millimeter-wave compact radio-frequency digital integrated front-end module according to claim 1, characterized in that: The upper surface of the substrate layer is isolated into two areas by the isolation frame (3) and the cover plate (4), one of which is used to seal the precursor compound bare chip (1) and the first metal pad (8) and the second metal pad (9) matched therewith, and the other is used to seal the silicon-based chip group (2) and the third metal pad (12) and the fourth metal pad (13) matched therewith.

8. The microwave-millimeter-wave compact radio frequency digital integrated front-end module according to claim 1, characterized in that: The silicon-based chip group (2) comprises a plurality of silicon-based chip modules (2-1) stacked in an upper and lower layer, wherein the silicon-based chip module (2-1) comprises a carrier board (2-1-1) and a silicon-based chip (2-1-2) located on the carrier board (2-1-1), and two silicon-based chip modules (2-1) are connected via BGA solder balls between the carrier boards (2-1-1).

9. The microwave-millimeter-wave compact radio frequency digital integrated front-end module according to claim 1, characterized in that: The front-end module further comprises a motherboard (26), wherein the motherboard (26) is connected to the BGA solder balls for signal transmission in the first group of BGA solder balls (6) via microstrip lines on the PCB.

10. The microwave-millimeter-wave compact radio frequency digital integrated front-end module according to claim 1, characterized in that: The heights of the first metal pad (8) and the second metal pad (9) are adapted to the height of the previous compound bare chip (1); the height of the third metal pad (12) is adapted to the height of the silicon-based chip group (2); and the height of the fourth metal pad (13) is adapted to the height of the silicon-based chip module (2-1) located at the bottom layer in the silicon-based chip group (2).

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