Semiconductor ceramic shell and ceramic substrate application solutions in the UAV industry

Charpter 1 Lightweight quantification and structural strength

1. Lightweight advantage
2. Material density optimization

The density of aluminum nitride (AlN) ceramic substrates is 3.26 g/cm³, slightly higher than that of traditional metal materials (such as aluminum alloys at 2.7 g/cm³). However, their high thermal conductivity (180-220 W/m·K) allows for thinner substrate designs, reducing overall weight by 20-30%. AMB (Active Metal Bonding) substrates can be bonded directly using copper layers, with thicknesses controlled to within 0.25 mm, supporting 600A power modules.

2. Integrated structural design

The low-temperature cofired ceramic (LTCC) substrate adopts multi-layer cabling technology (supporting more than 10 layers of wiring), integrated antenna, filter and other radio frequency elements, the volume is more than 60% smaller than the traditional PCB, significantly reducing the weight of the uav communication module. After using the LTCC RF module, the communication distance is increased to 15 km, and the weight is increased by only 5%.

2. Structural strength and reliability
3. Mechanical properties

-Bendural strength: Silicon nitride (Si ₃ N ₄) ceramic carrier plate can withstand up to 600 MPa, which is better than aluminum alloy (about 250 MPa) and titanium alloy (about 550 MPa), and is suitable for UAV power system in high vibration environment.

-Fracture toughness: Through ZrO phase transformation toughening technology, the fracture toughness of ceramic tube shell is improved to 15 MPa·m/, and the impact resistance is 70% higher than that of traditional ceramics.

2. Environmental resistance

-Thermal cycle life: The life of the AMB substrate under-40℃~150℃ temperature cycle is more than 50,000 times, ensuring the stability of the UAV inverter under extreme temperature difference.

-Air tightness package: Al ₂ O ₃ ceramic tube shell adopts Au-Sn co-crystal welding technology, and the package air tightness is up to <110 ⁸ Pa · m³ / s, to ensure the long-term stable operation of MEMS sensor in dust and humid environment.

3. Key application scenarios and technical parameters
4. Power electronic module

-AMB substrate: supports 1200V/600A silicon carbide power module with thermal conductivity of 220 W/m·K, which improves the efficiency of the main inverter of the UAV by 15% and reduces the failure rate to 0.1 times / 1000 hours.

-DBC substrate: aluminum nitride substrate withstand pressure> 3 kV, used for battery management system (BMS), temperature difference control accuracy ± 2℃, cycle life exceeds 2000 times.

2. RF and sensor module

-LTCC substrate: dielectric loss <0.001@28 GHz, support 5G millimeter wave communication, and anti-electromagnetic interference increased to 10 kV / m.

-MEMS packaging: laser drilling aperture <50 μm to achieve sensor micron accuracy (BMP pressure sensor ±0.1 hPa error).

4. Future technology direction

-Nanoceramic technology: developing nano-modified AlN powder with a target thermal conductivity> 250 W / m · K, further reducing the thickness and weight of the substrate.

-Gradient material design: the metal-ceramic transition layer reduces the interfacial stress, reduces the processing cost by 30%, and adapts to the needs of the micro-UAV.

Semiconductor ceramic tube shell and carrier plate have become the core material of lightweight and reliability of uav through high thermal conductivity, high strength and precision packaging technology

• heat management

1. Technical advantages of semiconductor ceramic tube and shell
2. High thermal conductivity and heat diffusion performance

The ceramic tube shell (such as Al ₂ O ₃, AlN material) can reach 170 W / m · K (aluminum nitride), which is 6 times of the aluminum substrate, and can quickly transfer the heat of the chip to the external environment. Its multi-layer wiring structure design (such as CDIP and CPGA packaging) can optimize the heat distribution, avoid local overheating, and is suitable for the packaging and heat dissipation of high-power electronic components of uav.

2. Thermal stability and low thermal expansion coefficient

The thermal expansion coefficient of the ceramic material (YSZ yttrium stable zirconium oxide is 10.510 ⁶ / ℃) is close to the chip silicon material (2.610 ⁶ / ℃), reducing the risk of packaging cracking caused by thermal stress and improving the reliability of the UAV in extreme temperature environment.

3. Lightweight of structure and corrosion resistance

The ceramic density (silicon carbide 3.1 g / cm³) is lower than that of metal materials, and has high hardness (the wear resistance of alumina bearing is 5 times that of steel parts), which is suitable for the long-term stable operation of UAV in the harsh environment such as dust and humidity.

2. Design parameters of the ceramic plate-loading plates
3. Composite heat dissipation flow channel structure

Using liquid cooling and air-cooled flow channel staggered parallel design (S-type liquid cooling flow channel + vertical air cooling channel), combined with semiconductor refrigeration sheet (patent CN 222248092 U), the thermal diffusion efficiency is improved by more than 40%, and the temperature difference control accuracy reaches ± 2℃.

2. Optimization of heat stress resistant materials

Enhance the thermal shock resistance of ceramic carrier plate (silicon nitride base) by doping modification technology, it can withstand the instantaneous temperature difference impact of 800℃, and reduce the performance attenuation of uav power system (fuel cell, lithium battery) due to thermal cycle.

3. Integrated thermal management module

The built-in thermal conduction plate and flow channel integrated molding technology supports the heat dissipation requirements of heat flow density of 200 W / cm², and meets the active heat dissipation requirements of uav high-density integrated electronic system (5G communication module, flight control chip)

3. Comprehensive application scenario comparison

component ​	​ technical parameter ​	Uv application scenarios
Semiconductor ceramic tube and shell	The thermal conductivity is 170 W / m · K and the thermal expansion coefficient is 10.510 ⁻⁶/℃	Flight control chip packaging, engine sensor protection cover
Ceramic board	Liquid cooling / air cooling composite heat dissipation, temperature difference control of ± 2℃, heat shock resistance temperature difference of 800℃	Lithium battery thermal management, fuel cell stack electrolyte substrate

The two types of materials are complementary in the thermal management of the UAV: ceramic tube shells focus on the packaging stability of electronic devices, while ceramic carriers focus on the active heat dissipation of high-power systems. Future technical iterations include, but are not limited to, nano-ceramic coatings (improving interface thermal conductivity) and 3D flow channel topology optimization (reducing thermal resistance).

• behaviour of electricity

1. High-frequency signal transmission and low-loss performance
2. Low-dielectric loss and high-frequency stability

-Aluminum nitride (AlN) ceramics: dielectric constant ε 8.8 @ 1 MHz, loss angle tangent tan δ <0.001, support signal transmission of millimeter-wave frequency band (24-40 GHz), loss low to <0.3 dB / cm, improve the transmission efficiency of uav radar and communication module (such as the millimeter-wave radar module of DJI Matrice 300 RTK).

-Silicon nitride (Si ₃ N ₄) carrier board: dielectric constant ε 7.5@10 GHz, equipped with 5G map transmission system, reduce signal delay, and ensure the real-time transmission of 8K HD video stream.

2. High insulation and anti-interference ability

-Aluminum oxide (Al₂O₃) ceramic: insulation resistance>10¹² Ω·cm, breakdown strength>15 kV/mm, isolate the electromagnetic interference of high power electric adjustment module (ESC) of UAV, and reduce the risk of signal crosstalk.

-Metallic shielding layer: gilding / nickel layer shielding efficiency of ceramic carrier plate surface> 60 dB@1 GHz, inhibiting the electromagnetic interference of uav multi-band communication (2.4 GHz / 5.8 GHz).

2. High-density integration and signal integrity
3. Multi-layer wiring and 3 D interconnection technology

-LTCC (low temperature co-fired ceramic) substrate: supports 12 layers of wiring, line width / line distance of 50 μ m, integrated uav flight control chip, gyroscope and sensor, the volume is 50% smaller than the traditional PCB.

-TSV (silicon through hole) ceramic carrier plate: vertical interconnection density> 400 holes / cm², shorten the high frequency signal path and reduces the delay by 25%, which is suitable for the heterogeneous integration of FPGA and AI processor.

2. Thermal expansion coefficient (CTE) matching and reliability

-AlN ceramics: CTE 4.510 ⁶ / ℃, highly matched with GaN power device (CTE 5.610 ⁶ / ℃), interface thermal stress <40 MPa, avoid solder joint cracking due to temperature fluctuations (SiC MOSFET package of UAV battery management system).

-Si ₃ N ₄ ceramics: CTE 3.010 ⁶ / ℃, suitable for silicon carbide (SiC) chip, improve the electrical stability in high temperature environment (> 150℃), suitable for the high voltage power module of hydrogen fuel cell UAV.

3. Environmental corrosion resistance and long-term reliability
4. Air-tight packaging and moisture-proof performance

-HTC CC (high temperature co-fired ceramic) tube shell: air tightness <110 ⁹ Pa · m³ / s (meet MIL-STD-883 standard), internal humidity <500 ppm, protect the lidar photodetector from water vapor erosion.

-Au-Sn co-crystal welding: the melting point of solder is 280℃, and the air tightness is better than epoxy resin packaging, which is suitable for high-precision data acquisition of uav MEMS pressure sensor.

2. Salt spray resistance and chemical corrosion

-The surface coating (such as chemical plating Ni-Pt) passed the ASTM B117 salt spray test for> 1000 hours, tolerating the high salt spray environment in coastal areas and ensuring the circuit stability in the UAV offshore inspection mission.

-Zirconia toughened ceramics (ZTA): bending strength> 600 MPa, acid and alkali corrosion resistance, suitable for the explosion-proof electrical module of industrial UAV in the chemical plant area.

Iv. Material and process innovation cases

1. AMB (active metal brazing) substrate

-Silicon nitride AMB substrate thermal conductivity 110 W / (m · K), supports 1200 VSiC power module, which improves the efficiency of the main uav inverter by 12% (such as the electric rotor drive system of Ehang EH 216-S).

-Copper layer thickness tolerance ± 3%, current distribution uniformity error <5%, reduce the risk of local overheating during high-power operation.

2. Laser direct writing technique (LDT)

-Achieve precision patterning of 2 μm line width for impedance matching of millimeter wave antenna arrays, reducing signal reflection loss (ceramic antenna substrate for 5G UAV communication modules).

-The machining accuracy error is <± 1 μ m, ensuring the yield of high-density interconnection (> 99.9%), and adapting to the compact RF front end of the micro-UAV (swarm UAV).

The core advantages of semiconductor ceramic tube shell and carrier plate in the electrical performance of UAV are:

1. High frequency and low loss: low dielectric constant (AlN / Si ₃ N ₄) and multi-layer wiring (LTCC / HTCC) support millimeter wave communication;
2. High-density integration: 3 D interconnection (TSV) and micropackaging (CQFN) to realize the miniaturization of flight control and perception module;
3. Environmental tolerance: Airtight packaging (HTCC) and anti-corrosion coating to ensure long-term reliability under complex working conditions;
4. Process breakthrough: AMB and LDT technology promote the performance jump of high-power and high-precision devices.

• environmental suitability

1. High-temperature stability and heat-shock resistance

High temperature resistance: silicon nitride (SiN) and zirconia (ZrO) based ceramics can withstand 1200℃ high temperature for a long time, which is suitable for the packaging of hot end components of UAV engines. The ceramic coating of turbine blades can reduce the surface temperature by more than 200℃ and extend the engine life by 40%.

Thermal shock resistance: through the ZrO phase change hardening technology, the ceramic fracture toughness is increased from 3 MPa · m / to 15 MPa · m /, which can withstand severe temperature fluctuations (-60~300℃ cycle test).

2. High thermal conductivity and highly efficient heat dissipation

Thermal conductivity advantage: the thermal conductivity of aluminum nitride (AlN) ceramic substrate reaches 170 W / m · K, which is 6 times that of traditional aluminum substrate. In the battery management system (BMS), the temperature difference of battery pack can be controlled in ± 2℃, and the cycle life exceeds 2000 times.

Thermal cycle life: the active metal brazing (AMB) ceramic substrate supports the operation of 1200V / 600A class silicon carbide power module, the thermal cycle life exceeds 50,000 times, and the failure rate of the main inverter is reduced to 0.1 times / thousand hours.

3. Resistance to electromagnetic interference and high-frequency performance

Low dielectric loss: The low temperature co-fired ceramic (LTCC) substrate has a dielectric loss as low as 0.001 in the 5G communication band (28 GHz), which supports remote communication of drones up to 15 km and improves the anti-interference capability by 50%.

Electromagnetic shielding capability: ferrite ceramic wave absorption material decay to more than 20 dB, improving the stealth performance of military uav.

4. Mechanical strength with lightweight

Bending strength: the bending strength of silicon carbide based ceramic carrier board is over 400 MPa, which can withstand the requirements of 0.1 mm deformation of UAV high speed rotor system.

Lightweight design: the ceramic density (such as silicon carbide 3.1 g / cm³) is reduced by 30% less than that of titanium alloy (4.5 g / cm³), while maintaining the structural strength to help improve the endurance of the UAV.

1. Environmental protection and airtightness

Corrosion resistance: alumina (Al ₂ O ₃) ceramic shell in the desert environment wear resistance is 5 times higher than the steel parts, salt spray test tolerance of 500 hours.

Packaging air tightness: MEMS sensor adopts Al ₂ O ₃ ceramic packaging with Au-Sn cocrystal welding, and the air tightness is <110 Pa · m/s, ensuring the micron accuracy under-40℃ ~150℃ working conditions.

Sixth, integration and miniaturization

High-density wiring: LTCC technology realizes multi-layer wiring through laser drilling (aperture <50 μ m), which reduces the volume of the navigation module by 60%.

Miniized adaptation: silicon nitride substrate to 150 W / (m · K) thermal conductivity and smaller size, adapted to the compact space requirements of miniature eVTOL.

Through nanomodification, gradient design and additive manufacturing (such as SLM technology), the performance of ceramic materials has been continuously optimized, and their environmental adaptability has covered core systems such as UAV power, communication and sensing.

• Size miniaturization and integration improvement

1. High-density integration capability of high-temperature co-fired ceramic (HTCC) technology
2. Multi-layer wiring structure

HTC CC adopts 1500-1800℃ high temperature cocombustion process, supports high melting point metal wiring such as tungsten and molybdenum, and can realize the three-dimensional circuit integration of more than 20 layers. In the packaging of optical communication module, HTCC shell realizes 3 D interconnection through micron-level through-hole (aperture <50 μ m), which reduces the packaging volume of RF filter (SAW / BAW) by 60% compared with the traditional scheme.

2. Miniature packaging and adaptation

In the uav MEMS sensor, HTCC ceramic tube shell (CLCC package) realizes 0.5 mm 0.5 mm micro packaging through laser punching technology, and supports the integration of air pressure sensing chip with ± 0.1 hPa accuracy, meeting the requirements of centimeter-level fixed height spraying of agricultural UAV.

2. High-frequency integration advantage of low-temperature co-fired ceramic (LTCC) substrate
3. High frequency signal integrity

The LTCC substrate has a dielectric loss as low as 0.001 in the 5G millimeter wave band (28 GHz), supports the integrated design of strip line and grounding hole, improves the communication distance of the UAV RF front module to 15 km, and reduces the module size to 10 mm 10 mm 1.2 mm.

2. Embedded and passive device integration

Through LTCC multi-layer structure integrating embedded capacitance (tolerance range 1-100 nF) and inductor (1-10 nH), the number of external components is reduced by more than 60%, the volume of navigation module is reduced by 60% and the anti-electromagnetic interference capability is improved to 10 kV / m.

3. Active metal brazing (AMB) supports the high power density of ceramic carrier board
4. High thermal conductivity is combined with high power density

The AlN-AMB substrate has a thermal conductivity of 220 W/m·K, which supports the silicon carbide power module (1200V/600A class) to achieve a 15% efficiency improvement in the main inverter of the UAV. At the same time, the power density per unit area reaches 80 W/cm², which is 5 times higher than that of the traditional FR-4 substrate.

2. Ultra-thin structure design

Using 0.25 mm thick aluminum nitride substrate combined with 0.3 mm copper layer brazing reduces the thickness of eVTOL motor drive module to 1.8 mm, which helps the EH 216-S manned UAV to reduce the weight by 12%.

Fourth, the physical properties of ceramic materials enable miniaturization

1. Thermal expansion coefficient matching

Alumina ceramic (CTE 6.5 ppm / ℃) is close to silicon chip (CTE 4.2 ppm / ℃), which can reduce the thermal stress of UAV image sensor package by 70% and reduce the package size of CMOS chip to 3 mm 3 mm.

2. Mechanical strength and lightweight balance

The bending strength of silicon carbide ceramic carrying board is up to 600 MPa. When it is used in the packaging of UAV rotor drive circuit, the carrying capacity of unit weight is 1.8 times that of aluminum alloy, and the weight of the structural parts is reduced by 30%.

5. Advanced packaging processes drive system-level integration
6. System-level packaging (SiP) application

Using HTCC / LTCC hybrid integration technology, the flight control chip, gyroscope and pressure sensor are integrated into 15 mm 15 mm ceramic substrate, which reduces the volume of the flight control module by 75% and power consumption by 40% compared with the traditional scheme.

2. 3D heterogeneous integration technology

Through the vertical interconnection between TSV (silicon through hole) and ceramic substrate, 10 layers of uav millimeter wave radar transceiver module are stacked, the signal delay is reduced to 0.3 ps / mm, and the packaging height is controlled within 2.5 mm.

Technology development trend

Nanoceramic coatings (such as nano-titanium oxide) will further enhance the density of packaging surfaces, supporting the manufacture of ultra-thin substrates below 0.1 mm; microwave-assisted sintering technology can reduce HTCC processing energy consumption by 50%, driving a 30% decrease in the cost of ceramic packaging for drones. The penetration rate of ceramic substrates in drone electronics systems is expected to increase from the current 22% to 45%.

• Breakthrough innovation

1. Breakthrough in extreme environmental adaptability
2. Thermal shock resistance and fracture toughness

Using ZrO ₂ phase change toughening technology, the ceramic fracture toughness is increased from 3 MPa · m¹ / ² to 15 MPa · m¹ / ², which can withstand the violent temperature change cycle of-60~300℃ and ensure the stability of the engine turbine blade in high temperature combustion environment.

The silicon nitride (Si₃N₄) ceramic substrate has a bending strength of up to 600 MPa through the design of gradient structure, and its thermal expansion coefficient is highly matched with that of silicon carbide chip (CTE 3.0×10⁻⁶/℃), which reduces the risk of packaging failure caused by thermal stress.

2. Air tightness and corrosion resistance

The Al ₂ O ₃ ceramic package of Au-Sn co-crystal welding realizes air tightness <110 ⁸ Pa · m/s, combined with nano titanium oxide coating, enables the MEMS sensor to maintain the micron accuracy of ± 0.1 hPa at-40~150℃, meeting the centimeter level requirement of agricultural uav. Alumina ceramic pipe shell through the salt spray test> 500 hours, wear resistance than steel parts increased 5 times, suitable for desert and other harsh environment.

2. High-frequency communication and signal integrity innovation
3. millimeter-wave communication performance

The low temperature co-fired ceramic (LTCC) substrate has a dielectric loss as low as 0.001 in the 28 GHz band, and integrates a strip line and embedded capacitor, which extends the communication distance of UAV to 15 km and improves the anti-interference capability by 50%.

Ferric oxide ceramic wave absorption material to radar wave attenuation of more than-20 dB, combined with silicon carbide based wave absorption coating, significantly improve the stealth performance of military uav.

2. 3 D integration and miniaturization

TSV (silicon through hole) technology realizes the 10 layers of ceramic carrier plate, the signal delay is reduced to 0.3 ps / mm, the packaging height is controlled within 2.5 mm, and the eVTOL millimeter wave radar module is adapted.

Laser direct writing technology (LDT) realizes the precision wiring of 2 μ m wire width, which is used for the impedance matching of millimeter-wave antenna array to reduce the signal reflection loss.

3. High power and thermal management performance jump
4. Breakthrough in power electronics module efficiency

The active metal brazing (AMB) SiC substrate supports 1200V / 600A power module, the thermal cycle life reaches 50,000 times, the main inverter efficiency is increased by 15%, and the failure rate is reduced to 0.1 times / thousand hours.

The thermal conductivity of aluminum nitride (AlN) ceramic substrate is 220 W / m · K. When applied to lithium battery BMS, the temperature difference of the battery pack is controlled in ± 2℃, and the cycle life exceeds 2000 times.

2. Active heat dissipation and heat balance

The liquid cooling and air cooling composite flow channel design (such as S-type liquid cooling + vertical air cooling channel), combined with the semiconductor refrigeration sheet, the thermal diffusion efficiency is improved by 40%, and the temperature difference control accuracy is ± 2℃, which meets the working requirements of the fuel cell stack below 800℃.

4. Intelligent materials and system integration
5. Adaptive deformation structure

Shape memory ceramics (SMC) is applied to wing design to achieve 20° adaptive aerodynamic deformation and optimize low-altitude flight efficiency.

The piezoelectric ceramic (PZT) MEMS sensor realizes self-power supply through vibration energy collection, and supports the cooperative control of UAV cluster.

2. Green manufacturing and recycling

Microwave-assisted sintering technology improves the reutilization rate of waste ceramics to 85%, and the nano-titanium oxide coating realizes the surface self-cleaning of the solar UAV, and improves the photoelectric conversion efficiency by 8%.

Typical technical index comparison

qualification	The traditional scheme	Ceramic innovation solutions	Performance improvement
Thermal cycle life	<10 Thousand times	The AMB substrate has reached 50,000 times	Five times
haul up	10 Kilometers	LTCC millimeter wave scheme up to 15 km	50%
gas tightness	1×10⁻⁶ Pa·m/s	The Au-Sn ceramic package is <110 ⁸	Two orders of magnitude
The whole machine weight loss	–	C / SiC rotor lose weight by 30%	–
Battery cycle life	1000 Times	AlN Base plate BMS up to 2,000 times	100%

Ceramic materials are reconstructing the core technology system of UAV through innovations such as AlN thermal conductivity 250 W / m · K), 3D integration (TSV stacking) and intelligent functionalization (adaptive deformation).

Chapter 7: New UAV technology

1. High thermal conductivity and thermal management capability
2. Aluminum nitride (AlN) ceramic substrate

Its thermal conductivity reaches 170-220 W/m·K (six times that of aluminum substrates), significantly enhancing the heat dissipation efficiency of power electronic modules (inverters, silicon carbide power devices). The cargo drone uses a AlN substrate to package the battery management system (BMS), keeping the temperature difference within ±2℃ and achieving a cycle life exceeding 2000 cycles.

2. Active metal brazing (AMB) substrate

By bonding copper layers with titanium silver copper brazing, the thermal cycle life exceeds 50,000 times, supporting the stable operation of silicon carbide power modules at 1200V/600A class, improving the efficiency of eVTOL main inverter by 15% and reducing the failure rate to 0.1 times per thousand hours.

2. High-frequency and RF performance optimization
3. Low-temperature co-fired ceramic (LTCC) substrate

With dielectric loss (tan δ <0.001) and multi-layer wiring capability, it is suitable for 5G millimeter-wave communication and navigation systems.

2. Aluminum oxide (Al ₂ O ₃) ceramic tube shell

The 28 GHz frequency band dielectric loss is only 0.001, which optimizes the antenna signal transmission efficiency and ensures the communication stability of uav in the complex electromagnetic environment.

3. Mechanical strength and lightweight design
4. Flexural strength and impact resistance

The bending strength of the ceramic carrier board is more than 400 MPa (such as the AMB substrate), which can withstand the high-frequency vibration and impact in the UAV flight. The deformation of the carbon fiber reinforced silicon carbide (C / SiC) rotor is less than 0.1 mm under high-speed rotation, and the accuracy is better than that of traditional metal materials.

2. Lightweight advantage

The ceramic density (silicon carbide 3.1 g / cm³) is significantly lower than that of titanium alloy (4.5 g / cm³). Through structural optimization, the weight of the components can be reduced by 30% and improve the endurance of the UAV.

4. Environmental adaptability and reliability
5. Air tightness and corrosion resistance

The Al ₂ O ₃ ceramic packaging substrate is welded by laser drilling (aperture <50 μ m) and Au-Sn common crystal, and the air tightness is <110 ⁸ Pa · m³ / s, ensuring the accuracy of the MEMS sensor in the temperature range of-40℃ ~150℃ (the pressure sensor can achieve ± 0.1 hPa accuracy).

2. Anti-electromagnetic interference (EMI)

The LTCC packaging technology improves the anti-electromagnetic interference capability of the navigation module to 10 kV / m, which is suitable for flight control in complex electromagnetic environment.

Semiconductor ceramic tube shell and carrier plate have become the core support materials for UAV power systems, communication modules and sensors through high thermal conductivity, high frequency stability, lightweight and environmental tolerance.