Miniaturized radio frequency microsystem with efficient heat dissipation
By employing a three-layer structure design and thermoelectric separation technology, the problems of excessive thickness and low heat dissipation efficiency in RF microsystems have been solved, resulting in a miniaturized RF microsystem with high-efficiency heat dissipation, suitable for the DC-40GHz frequency band.
Patent Information
- Application Number
- CN202511769141.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-13
AI Technical Summary
Existing RF microsystems face challenges such as excessive thickness and low heat dissipation efficiency in high integration and high power density designs, especially in multi-layer stacking and secondary packaging schemes where miniaturization and efficient heat dissipation are difficult to achieve.
The design employs a three-layer structure, including a top silicon interposer, a middle silicon interposer, and a silicon nitride substrate. Signal transmission and heat separation are achieved through RDL, TSV, BGA solder balls, and TCV, forming a closed cavity to improve heat dissipation efficiency. Nano-silver conductive adhesive and copper layers are used for heat conduction.
It achieves a miniaturized RF microsystem with low height and short heat dissipation path, reducing processing costs, improving space utilization and heat dissipation efficiency, and is suitable for the DC-40GHz frequency band.
Smart Images
Figure CN121532039A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of radio frequency microsystems technology, and more particularly to a miniaturized radio frequency microsystem with high-efficiency heat dissipation. Background Technology
[0002] With the widespread adoption of 5G communication and millimeter-wave radar technologies, radio frequency microsystems (RF microsystems) face the design challenge of simultaneously achieving high integration and high power density. Currently, there are two main implementation schemes based on silicon interposers: The first scheme uses three or more layers of stacked silicon interposers, forming a sealed cavity through bonding processes, and embedding the RF chip within the cavity. While this scheme achieves three-dimensional integration, the multi-layer stacking significantly increases process complexity, and its height is limited by the number of stacked layers and the size of the bonding balls. The second scheme uses the silicon interposer as a chip carrier, soldering BGA balls onto the non-chip side, and then soldering the entire assembly to a ceramic packaging substrate for secondary fan-out. While this design can improve interconnect density, the heat transfer path is longer, and the secondary packaging increases the system thickness, making it difficult to meet miniaturization requirements. Summary of the Invention
[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a miniaturized radio frequency microsystem with high-efficiency heat dissipation, characterized by low height and short heat dissipation path, which can solve the problems of excessive thickness and low heat dissipation efficiency in existing architectures.
[0004] To achieve the above objectives, one aspect of the present invention provides a miniaturized radio frequency microsystem with high-efficiency heat dissipation, comprising, from top to bottom, a top silicon interposer, an intermediate silicon interposer, and a silicon nitride substrate, wherein the lower layer of the intermediate silicon interposer is provided with BGA solder balls. The top silicon adapter board and the middle silicon adapter board are provided with RDL and TSV, and the silicon nitride substrate is provided with copper layer and TCV. The top silicon adapter board and the middle silicon adapter board realize the transmission of radio frequency, power supply and control signals through RDL and TSV. The silicon nitride substrate realizes the transmission of power supply and control signals through copper layer and TCV. The middle silicon adapter board transmits signals with the outside through the BGA solder balls of the lower layer. Multiple enclosed cavities are formed between the lower RDL of the top silicon interposer, the upper RDL of the middle silicon interposer, the TSV of the middle silicon interposer, the lower RDL of the middle silicon interposer, and the upper copper layer of the silicon nitride substrate. High-power RF chips and low-power RF chips are mounted on the lower layer of the top silicon interposer and disposed in the cavities. The high-power RF chips and low-power RF chips are connected to the lower RDL of the top silicon interposer through metal leads.
[0005] The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to the above-described aspects of the present invention has the characteristics of low height and short heat dissipation path, which can solve the problems of excessive thickness and low heat dissipation efficiency in the existing architecture. Attached Figure Description
[0006] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 A side view of a miniaturized radio frequency microsystem with high-efficiency heat dissipation according to an embodiment of the present invention; Figure 2 This is a top view of a top silicon adapter board according to an embodiment of the present invention; Figure 3 This is a bottom view of a top silicon adapter board according to an embodiment of the present invention; Figure 4 This is a top view of an intermediate silicon interposer board according to an embodiment of the present invention; Figure 5 This is a bottom view of an intermediate silicon interposer board according to an embodiment of the present invention; Figure 6 This is a top view of a silicon nitride substrate according to an embodiment of the present invention; Figure 7 This is a bottom view of a silicon nitride substrate according to an embodiment of the present invention. Detailed Implementation
[0007] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0008] One embodiment of the present invention provides a miniaturized radio frequency microsystem with high-efficiency heat dissipation, such as... Figures 1 to 7 As shown, the miniaturized radio frequency microsystem with high-efficiency heat dissipation in this embodiment of the invention includes, from top to bottom, a top silicon interposer 1, an intermediate silicon interposer 2, and a silicon nitride substrate 3. The lower layer of the intermediate silicon interposer 2 is provided with BGA solder balls 4.
[0009] The top silicon interposer 1 and the middle silicon interposer 2 are provided with RDL (Redistribution Layer) 5 and TSV (Through Silicon Via) 6; the silicon nitride substrate 3 is provided with copper layer 7 and TCV (Through Copper Via) 8.
[0010] The top silicon interposer 1 and the middle silicon interposer 2 transmit radio frequency, power supply, and control signals through RDL5 and TSV6. The silicon nitride substrate 3 transmits power supply and control signals through copper layer 7 and TCV8. The top silicon interposer 1 and the middle silicon interposer 2 are metallized together using copper-tin eutectic solder.
[0011] The intermediate silicon interposer 2 and the silicon nitride substrate 3 are soldered together using gold-tin solder. Four enclosed cavities are formed between the lower RDL5 of the top silicon interposer 1, the upper RDL5 of the intermediate silicon interposer 2, the TSV6 of the intermediate silicon interposer 2, the lower RDL5 of the intermediate silicon interposer 2, and the upper copper layer 7 of the silicon nitride substrate 3, achieving electromagnetic shielding between the four cavities and improving isolation.
[0012] The high-power RF chip 9 and the low-power RF chip 10 transmit signals to the RDL5 on the lower layer of the top silicon adapter board 1 through metal leads 11. The metal leads 11 are made of gold.
[0013] The signals from the high-power RF chip 9 and the low-power RF chip 10 are transmitted via metal leads 11 to the lower RDL5 of the top silicon adapter board, then to the upper RDL5 of the middle silicon adapter board 2, and then via TSV6 of the middle silicon adapter board 2 to the lower RDL5 of the middle silicon adapter board 2. Finally, they interact with the external system via the BGA solder balls 4 on the lower layer of the middle silicon adapter board 2.
[0014] The top silicon interposer 1 has a height of 200um, the middle silicon interposer 2 has a height of 200um, the silicon nitride substrate 3 has a height of 300um, the BGA solder ball 4 has a height of 400um, the high-power RF chip 9 has a height of 100um, and the low-power RF chip 10 has a thickness of 100um.
[0015] The main heat dissipation path for the four high-power RF chips 9 is through the top silicon adapter plate 1, which transmits heat upwards. The thermal conductivity of the silicon adapter plate is around 148 W / m·k, which can effectively dissipate the heat generated by the high-power RF chips 9.
[0016] like Figure 1 , Figure 3 , Figure 4 As shown, the high-power RF chip 9 and the low-power RF chip 10 are attached to the lower layer of the top silicon adapter plate 1 using nano-silver conductive adhesive with high thermal conductivity (thermal conductivity around 200W / (m·K)). They are located in the cavity area of the middle silicon adapter plate 2. The four high-power RF chips 9 are power amplifiers, and of the eight low-power RF chips 10, four are limiters and four are low-noise amplifiers.
[0017] like Figure 1 , Figure 2 , Figure 3 As shown, in the mounting areas of the high-power RF chip 9 and the low-power RF chip 10 corresponding to the top silicon adapter board 1, the TSV6 has a high hole density. The heat of the high-power RF chip 9 is transferred to the upper RDL5 of the top silicon adapter board 1 through the TSV6 and the top silicon adapter board 1. The upper RDL5 of the top silicon adapter board 1 is a full-surface pattern, forming an effective heat dissipation path. It has a large external heat dissipation contact surface, which can achieve efficient heat dissipation of the RF chip.
[0018] like Figure 4 As shown, the intermediate silicon interposer 2 has four cavities formed in the middle using a deep cavity etching process. Figure 1 , Figure 5 As shown, the intermediate silicon adapter board 2 transmits signals to the external system through the lower BGA solder balls 4.
[0019] like Figure 6 , Figure 7 As shown, the silicon nitride substrate 3 is manufactured using the DPC (Direct Plated Copper) process. The upper copper layer 7 and the lower copper layer 7 are connected by TCV8 to transmit signals. Since the number of transmission layers of the top silicon adapter board 1 and the middle silicon adapter board 2 is limited compared to the number of multilayer PCBs, some control and power supply signals can be transmitted through the copper layers 7 of the upper and lower layers of the silicon nitride substrate 3 to increase the transmission path.
[0020] In summary, the miniaturized RF microsystem with high-efficiency heat dissipation of this invention stacks two silicon interposer layers and one silicon nitride substrate to form an RF microsystem with built-in chips. The top silicon interposer integrates both high-power and low-power RF chips. The silicon interposer serves as the main wiring layer, and the silicon nitride substrate as the slave wiring layer. RF signals are transmitted on the top and middle silicon interposer layers, while control and power supply signals are transmitted on the top, middle, and bottom silicon nitride substrates. The heat from the high-power RF chip is primarily transferred upwards via the top silicon interposer layer, while signals are transmitted to the external system via the BGA balls on the lower layer of the middle silicon interposer layer, achieving thermoelectric separation. The silicon nitride substrate and silicon interposer seal the cavity, and the silicon nitride substrate and BGA solder balls are at the same structural level, improving space utilization. As a slave wiring layer, the silicon nitride substrate has lower surface wiring precision and larger via sizes than the silicon interposer layer, resulting in lower processing costs.
[0021] The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to the embodiments of the present invention has the following beneficial effects: 1. Compared with existing multilayer stacked silicon-based radio frequency microsystems, this invention uses a silicon nitride substrate to achieve cavity sealing, and the lower layer of the intermediate silicon interposer board achieves signal transmission with the outside through BGA solder balls. The silicon nitride substrate and BGA solder balls are at the same structural level, which has the advantage of low height. 2. Compared to the aluminum nitride and alumina ceramic materials used in the POP stacking architecture of silicon interposer + ceramic shell, the thermal expansion coefficient of silicon nitride in this invention is 2.8-3.2 ppm / ℃, and that of high-resistivity silicon is 2.6-3.3 ppm / ℃. The thermal expansion coefficients of silicon nitride and high-resistivity silicon are more well matched (the thermal expansion coefficient of aluminum nitride is about 4.5 ppm / ℃, and that of alumina is about 7.2 ppm / ℃). 3. Compared with existing multilayer stacked silicon-based radio frequency microsystems, the present invention replaces the silicon interposer used for sealing with a silicon nitride substrate. The cavity is sealed by two silicon interposers and one silicon nitride substrate. The substrate used for cavity sealing is not used as a carrier for the chip or for high-density interconnection of signals. Therefore, it can be replaced with a lower-cost silicon nitride substrate. Thus, the present invention has the advantage of low cost. 4. This invention achieves separation of the heat transfer path and the signal transmission path of high-power radio frequency signals at a lower stacking height, which is beneficial for system integration.
[0022] 5. Compared with radio frequency microsystems that use a three-layer silicon interposer to achieve cavity sealing, this invention achieves thermoelectric separation while optimizing the stack-up design, reducing the height, and has the advantages of efficient heat dissipation, miniaturization and low cost, and can be applied to the DC-40GHz frequency band.
[0023] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A miniaturized radio frequency microsystem with high-efficiency heat dissipation, characterized in that, From top to bottom, it includes a top silicon interposer, an intermediate silicon interposer, and a silicon nitride substrate. The lower layer of the intermediate silicon interposer is provided with BGA solder balls. The top silicon adapter board and the middle silicon adapter board are provided with RDL and TSV, and the silicon nitride substrate is provided with copper layer and TCV. The top silicon adapter board and the middle silicon adapter board realize the transmission of radio frequency, power supply and control signals through RDL and TSV. The silicon nitride substrate realizes the transmission of power supply and control signals through copper layer and TCV. The middle silicon adapter board transmits signals with the outside through the BGA solder balls of the lower layer. Multiple enclosed cavities are formed between the lower RDL of the top silicon interposer, the upper RDL of the middle silicon interposer, the TSV of the middle silicon interposer, the lower RDL of the middle silicon interposer, and the upper copper layer of the silicon nitride substrate. High-power RF chips and low-power RF chips are mounted on the lower layer of the top silicon interposer and disposed in the cavities. The high-power RF chips and low-power RF chips are connected to the lower RDL of the top silicon interposer through metal leads.
2. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1, characterized in that, The cavity consists of four chambers, each containing one high-power radio frequency chip and two low-power radio frequency chips. The high-power radio frequency chip is a power amplifier, and the two low-power radio frequency chips are a limiter and a low-noise amplifier, respectively.
3. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1 or 2, characterized in that, In the mounting areas of high-power and low-power RF chips on the lower layer of the top silicon adapter board, the TSV has a high hole density. The heat from the high-power RF chip is transferred through the TSV and the top silicon adapter board to the RDL on the upper layer of the top silicon adapter board, achieving efficient heat dissipation of the RF chip.
4. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1 or 2, characterized in that, The silicon nitride substrate is manufactured using a direct copper plating process, and signal transmission between the upper and lower copper layers is achieved through TCV.
5. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1 or 2, characterized in that, The copper layer of the silicon nitride substrate is plated with nickel and gold, and the metal leads are made of gold.
6. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1 or 2, characterized in that, The top silicon adapter board and the middle silicon adapter board are metallized and bonded together by copper-tin eutectic solder; the middle silicon adapter board and the silicon nitride substrate are welded together by gold-tin solder.
7. The miniaturized radio frequency microsystem with high-efficiency heat dissipation according to claim 1 or 2, characterized in that, High-power and low-power RF chips are bonded to the lower layer of the top silicon adapter using nano-silver conductive adhesive.