Chapter 1 Reliability and Durability
I. Technical Advantages of Ceramic Shell
1. High Airtightness and Corrosion Resistance
Ceramic shell achieves high airtightness (HTCC process) through dense structure, effectively isolating corrosive media such as moisture and salt spray, and meeting the long-term stable operation of automotive electronics in harsh environments such as humidity and vibration.
2. Excellent thermal management performance
High thermal conductivity (aluminum oxide Al2O3: 24−28 W/m⋅K, aluminum nitride AlN: 170-200 W/m·K), quickly conducts the heat generated by power devices, and reduces the junction temperature gradient (such as the junction temperature gradient of SiC MOSFET module can be reduced to 5°C/mm).
Low thermal expansion coefficient (Al2O3: 7.1×10⁻⁶/°C, close to 3×10⁻⁶/°C of silicon chips), reducing packaging failure caused by thermal stress.
3. Mechanical and electrical reliability
High mechanical strength (alumina bending strength> 300 MPa, silicon nitride> 800 MPa), resistant to automobile vibration and impact.
High insulation resistance (> 10¹² Ω·cm) and low dielectric loss (tanδ<0.0002) ensure high-frequency signal integrity.
2. Core performance of ceramic substrate
1. Thermal-electric synergistic optimization
Silicon nitride (Si3N4) substrate with AMB (active metal brazing) process, thermal conductivity> 90 W/m·K, bending strength> 800 MPa, supports 15 kW/cm² heat dissipation requirements under 800V high-voltage platform.
The bonding strength between copper layer and ceramic> 20 MPa (AMB process), realizing high current transmission (such as BMS system single board current> 200A).
2. Structural adaptability
Three-dimensional wiring capability (such as LTCC substrate wiring density of 200 lines/mm), meeting the high-density integration requirements of domain controllers.
Gradient heat dissipation design (such as AlN-Al₂O₃ composite substrate) reduces the volume of power modules by 40%.
III. Typical application scenarios
1. Electric drive system
SiC power modules use aluminum nitride ceramic substrates, which reduce switching losses by 75% and support continuous operation at >150°C under 1200V/400A conditions.
2. Battery Management System (BMS)
Multilayer ceramic substrates realize thick copper circuits (copper thickness >300 μm), reduce Joule heat by 50%, and SOC estimation error <1%.
3. Sensors and ADAS
LTCC ceramic substrates (dielectric constant tolerance ±0.1) are used for 77 GHz millimeter wave radars, with signal loss <0.2 dB/cm and delay <10 ms.
Power system: IGBT modules use ceramic substrates to improve heat dissipation efficiency and extend battery life.
Sensor packaging: Oxygen sensors and temperature sensors use ceramic tube shells to ensure signal transmission stability.
High-voltage electronic control unit: Aluminum nitride substrate is used for 800V on-board charging system to ensure insulation and heat dissipation requirements
IV. Technology Trends
Material upgrade: Silicon nitride AMB substrate gradually replaces aluminum oxide, and the thermal conductivity of diamond copper substrate (DBC) exceeds 2000 W/m·K.
Process innovation: Laser activated metallization (LAM) achieves 5 μm line width accuracy, adapting to GaN high-frequency requirements.
Chapter 2 Lightweight and high-strength performance
I. Advantages of lightweight technical indicators
1. Low density and high specific strength
Ceramic material density is significantly lower than that of metal (aluminum oxide density is 3.9 g/cm³, silicon nitride is 3.2 g/cm³, and steel is 7.8 g/cm³). Combined with its high bending strength (silicon nitride>800 MPa), it can achieve a weight reduction of 30%-50% at the same strength.
2. Thin-wall design capability
The high mechanical strength of ceramics (aluminum oxide compressive strength>2000 MPa) allows thinner structural design. The wall thickness of HTCC (high temperature co-fired ceramic) tube shell can be as low as 0.3 mm, which is 50% thinner than metal packaging, and the overall package volume is reduced by 30%.
3. Integrated structure optimization
Multilayer ceramic substrate (LTCC) integrates passive components (resistors, capacitors) through three-dimensional wiring, reduces connectors and wiring harnesses, and reduces the weight of ECU modules by 15%-20%.
2. Advantages of high-strength technical indicators
1. Mechanical stability in extreme environments
Bending strength: silicon nitride (Si₃N₄) substrate>800 MPa, zirconium oxide toughened ceramic (ZTA)>1200 MPa, far exceeding aluminum alloy (300-500 MPa), and resistant to automotive vibration (acceleration>50g) and impact (IEC 60068-2-27 standard).
The ceramic substrate that can be used in the on-board charger (OBC) has a fatigue life of>1×10⁷ times in the 10-2000 Hz random vibration test, and no structural failure.
2. Thermal shock and creep resistance
Coefficient of thermal expansion (CTE) matching: Aluminum nitride (AlN) CTE is 4.5×10⁻⁶/°C, which is highly matched with SiC chips (4.0×10⁻⁶/°C), avoiding interface delamination under high temperature cycles (-40°C to 150°C).
High temperature strength retention rate: Silicon nitride has a strength retention rate of >90% at 800°C, which is better than metal materials (copper has a 50% drop in strength at 300°C).
3. Corrosion and wear resistance
Ceramic surface hardness >15 GPa (Vickers hardness), acid and alkali corrosion resistance (salt spray test >1000 hours without failure), suitable for harsh environments such as chassis electronic modules.
3. Typical application scenarios
1. Electric drive system
The SiC power module uses an aluminum nitride substrate, which reduces the weight of the module by 35%, while supporting mechanical vibration (amplitude ±1.5 mm) and thermal cycle shock under 1200V/600A conditions.
2. On-board sensors and ADAS
The ceramic tube shell (such as zirconium oxide) in the laser radar (LiDAR) has a density of 4.6 g/cm³ and a bending strength of >1000 MPa, which protects the zero displacement of optical components under collision conditions (50g impact).
3. Battery system
Ceramic insulating substrates (such as Al₂O₃) are used for BMS high-voltage sampling circuits, with a thickness of 0.5 mm, a weight reduction of 50% compared to FR4 substrates, and a withstand voltage of >3 kV/mm.
IV. Technology Evolution Direction
1. Composite Material Innovation
Silicon carbide fiber reinforced ceramic matrix composite (CMC), density <2.5 g/cm³, bending strength >1500 MPa, targeted for application in 800V electric drive system.
2. Advanced molding process
Injection molding ceramic (IMC) technology realizes complex three-dimensional structure, wall thickness <0.2 mm, and weight is 20% lower than traditional sintered ceramics.
3. Lightweight functional integration
Gradient porosity ceramics (such as foamed Al₂O₃) maintain strength (>200 MPa) while reducing density to 2.0 g/cm³, used for non-load-bearing parts such as vehicle antenna covers.
Semiconductor ceramic shells and carriers solve the contradiction between lightweight and high strength requirements of automotive electronics through low density, high specific strength, thin-wall design, and core properties such as vibration resistance, heat shock resistance, and corrosion resistance.
Chapter 3 Efficient Heat Dissipation and Thermal Management
I. Core Heat Dissipation Performance Indicators
1. Ultra-high Thermal Conductivity
Aluminum Nitride (AlN): Thermal conductivity 170-200 W/m·K, 7 times that of aluminum oxide (Al₂O₃, 24-28 W/m·K), can quickly export high-density heat from SiC/GaN power devices (1200V SiC module junction temperature gradient <5°C/mm).
Diamond Substrate: Thermal conductivity 2000 W/m·K (laboratory grade), used for LiDAR chip heat dissipation, local hot spot temperature reduced by 40%.
2. Low coefficient of thermal expansion (CTE) matching
The CTE of AlN is 4.5×10⁻⁶/°C, which is highly matched with SiC chips (4.0×10⁻⁶/°C), avoiding interface delamination under high temperature cycles (-40°C to 200°C) and improving thermal cycle life by >100,000 times (IEC 60068 standard).
3. High temperature stability
The ceramic substrate maintains strength at high temperatures: the strength retention rate of silicon nitride (Si₃N₄) at 800°C is >90%, supporting the long-term operation of the engine compartment ECU module in a 150°C environment.
2. Advanced heat dissipation process technology
1. Copper plating process optimization
Direct copper plating (DBC): The copper layer thickness reaches 300-600 μm, and the thermal resistance is as low as 0.15 K·cm²/W. It is used in 800V electric drive systems and supports a heat flux density of 15 kW/cm².
Active Metal Brazing (AMB): AlN substrate copper layer bonding strength > 20 MPa, withstand > 300°C brazing temperature, suitable for high power density IGBT modules.
2. Gradient heat dissipation structure design
Multilayer ceramic substrates (such as AlN-Al₂O₃ composite substrates) achieve smooth heat transfer from chip to shell through thermal conductivity gradient distribution (200→25 W/m·K), and the overall temperature rise of the module is reduced by 30%.
3. Microchannel liquid cooling integration
Ceramic tube shells are embedded with microchannels (line width <100 μm), and chip-level heat dissipation is achieved with coolant, and the power density is increased to 50 W/cm³ (traditional air cooling <10 W/cm³).
III. Typical application scenarios
1. Electric drive system
SiC inverter module uses AlN-AMB substrate, thermal resistance is reduced by 60%, and chip junction temperature is supported at a peak power of 300 kW <175°C (traditional solution >200°C).
2. On-board charger (OBC)
Multilayer LTCC substrate integrates heat dissipation vias (aperture 0.2 mm). After optimizing the thermal conductivity path, the volume of 11 kW OBC is reduced by 40%, and the efficiency is >95%.
3. ADAS and smart cockpit
The autonomous driving chip uses a diamond copper-clad substrate with a heat flux density >100 W/cm². When the computing power is increased to 1000 TOPS, the chip temperature is stabilized within 85°C.
IV. Technology evolution direction
1. Ultra-high thermal conductivity materials
Boron nitride nanotube reinforced ceramics (thermal conductivity >400 W/m·K), targeted for application in 800V electric drive systems.
Graphene-ceramic composite materials, anisotropic thermal conductivity (in-plane thermal conductivity >500 W/m·K).
2. Intelligent thermal management integration
Embedded thermistor ceramic sensors (accuracy ±0.5°C), real-time control of the cooling system, and energy consumption reduction by 20%.
Phase change material (PCM) is coupled with ceramic substrate to buffer transient thermal shock (such as rapid acceleration conditions).
3. Chip-package collaborative design
In 3D heterogeneous integration, the thermal conductivity of the ceramic interposer is > 200 W/m·K, which solves the thermal crosstalk problem under the chiplet architecture.
Summary: Through the three core advantages of ultra-high thermal conductivity, low thermal expansion matching, and high temperature stability, combined with innovative technologies such as copper cladding process, gradient heat dissipation, and microchannel integration, the heat dissipation efficiency of automotive electronic systems in high-voltage and high-power density scenarios is improved.
Chapter 4 Corrosion resistance and oxidation resistance
I. Intrinsic corrosion resistance of materials
1. Chemical stability
Ceramic materials such as alumina (Al2O3) and aluminum nitride (AlN) have high chemical inertness and significant acid and alkali corrosion resistance. The corrosion rate of silicon nitride (Si3N4) is less than 0.01mm/year in strong acid (such as concentrated sulfuric acid) and strong alkali (such as sodium hydroxide) environments.
Salt spray test: After the ceramic substrate passes the 1000-hour salt spray test (ASTM B117 standard), there is no pitting or peeling on the surface.
2. Anti-oxidation performance
Ceramic materials remain stable in high-temperature oxidizing environments (such as 150°C in the engine compartment). For example, the oxidation weight gain rate of aluminum nitride in air at 800°C is only 0.02mg/cm², which is much lower than that of metal materials (the oxidation rate of copper is more than 10 times higher).
2. Surface treatment and structural design
1. Densification process
The porosity of the ceramic shell formed by high-temperature sintering (HTCC process) is less than 0.5%, which effectively blocks the penetration of water vapor and corrosive media, and the airtightness reaches 1×10−9 Pa⋅m3/s.
2. Metallization layer protection
The copper layer formed on the ceramic surface by the AMB (active metal brazing) process has a bonding strength of >20MPa, and there are no micropores on the interface to avoid electrochemical corrosion. For example, after 1000 hours of testing in an 85°C humidity environment, the copper layer of the AMB silicon nitride substrate showed no oxidation or peeling.
III. Typical application scenarios
1. Battery management system (BMS)
In the case of electrolyte leakage (pH 1-13), the insulation resistance of the alumina ceramic substrate remains >1012Ω⋅cm, ensuring the reliability of the high-voltage sampling circuit.
2. Electric drive system
Silicon nitride substrates are used for 800V SiC power modules, which can withstand long-term corrosion by coolant (ethylene glycol-based), and the module life is >15 years (equivalent to 3000 thermal cycles).
IV. Technology evolution direction
Composite coating technology: Plasma spraying Al2O3-TiO_2 composite coating is used to increase the surface hardness of the ceramic to 15GPa, and the wear and corrosion resistance is increased by 3 times.
High-purity materials: AlN powder purity >99.95% (metal impurities <50ppm), reducing the risk of intergranular corrosion.
In summary, ceramic materials have shown significant advantages in automotive corrosive environments through chemical inertness, densification structure and advanced surface treatment processes, supporting the long-term reliability of high-voltage electrical systems under extreme conditions such as humidity, heat and salt spray.
Chapter 4 Intelligent Monitoring and Feedback
I. High-precision signal transmission and integration capabilities
1. Low dielectric loss and high-frequency stability
LTCC (low-temperature co-fired ceramic) substrates reduce the 77 GHz millimeter-wave radar signal loss to 0.2dB/cm through dielectric constant consistency control (εr tolerance ±0.1), ensuring ADAS system decision delay <10 ms.
2. Three-dimensional high-density interconnection
3D ceramic substrate stacking technology combined with TSV (silicon through-via) vertical interconnection, with a wiring density of 200 lines/mm, supports domain controller multi-sensor data fusion, and reduces power consumption by 30%.
2. Thermal-electric synergistic reliability guarantee
1. High temperature environment stability
The strength retention rate of silicon nitride (Si3N4) AMB substrate at 800°C is >90%, ensuring the long-term operation of the engine compartment ECU module in a 150°C environment.
2. Thermal shock resistance
The thermal expansion coefficient of the AlN ceramic substrate (4.5×10⁻⁶/°C) is highly matched with the SiC chip (4.0×10⁻⁶/°C), supporting 3000 thermal cycles (-40°C to 200°C) without interface stratification.
3. Intelligent monitoring system adaptability
1. Sensor integration advantages
Alumina ceramic substrates are used for BMS high-voltage sampling circuit, withstand voltage>3 kV/mm}, anti-electromagnetic interference characteristics make the battery SOC estimation error <1%.
2. Real-time feedback response
Diamond copper-clad substrate (thermal conductivity 2000W/m·K) is used for laser radar chip heat dissipation, local hot spot temperature is reduced by 40%, ensuring zero displacement of optical components under 50g impact.
IV. Material and process evolution direction
AMB process breakthrough: Active metal brazing technology achieves copper layer bonding strength>20MPa and void rate close to zero, adapting to the real-time monitoring needs of SiC module under 1200V/600 A working conditions.
Intelligent material integration: Gradient porosity ceramic substrate (such as foamed Al2O3) is embedded with a thermal sensor, the temperature monitoring accuracy reaches ±0.5℃, and the energy consumption of the dynamic control heat dissipation system is reduced by 20%.
In summary, ceramic tube shells and carriers provide underlying hardware support for automotive intelligent monitoring systems through high-frequency signal integrity, high-temperature stability, impact resistance and high-density integration capabilities
Chapter 5 Breakthrough Innovative Applications
I. Ultra-high thermal management performance
1. High thermal conductivity and low thermal expansion matching
The thermal conductivity of aluminum nitride (AlN) ceramic carriers reaches 170-200 W/m·K, which is highly matched with the thermal expansion coefficient of silicon carbide (SiC) chips (4.0 × 10-6/℃), supporting 15 kW/cm² heat flux density heat dissipation under 80V} high-voltage platform, and the junction temperature gradient can be reduced to 5℃/mm}.
The bending strength of silicon nitride (Si3N4) AMB carriers is >800 MPa, and the high temperature (800℃) strength retention rate is >90%, which is suitable for long-term operation in the engine compartment environment of 150℃.
2. Advanced technology improves heat dissipation efficiency
The DPC (direct copper plating) ceramic substrate achieves double-sided copper heat dissipation through laser drilling and electroplating hole filling technology, and the heat flux density is increased from 50W/cm² to 200W/cm², and the power density exceeds 4.5kW/L.
The copper layer bonding strength of the AMB (active metal brazing) process is >20MPa, and the void rate is close to zero, supporting long-term stable operation under 1200 V/600A conditions.
2. High-density integration and signal integrity
1. Three-dimensional packaging and high-frequency performance
The dielectric constant tolerance of the LTCC (low-temperature co-fired ceramic) substrate is ±0.1, which reduces the signal loss of the 77GHz millimeter-wave radar to 0.2 dB/cm, ensuring ADAS decision delay <10ms.
The 3D ceramic substrate stacking technology combined with TSV (through silicon via) vertical interconnection has a wiring density of 200 lines/mm} and reduces power consumption by 30%.
2. Air tightness and environmental interference resistance
The air tightness of the HTCC (high temperature co-fired ceramic) shell reaches 1× 10-9 Pa·m³/s, passes the 1000-hour salt spray test (ASTM B117), and withstands harsh environments such as electrolyte leakage (pH 1-13).
The aluminum oxide (Al2O3) substrate withstands voltage>3kV/mm}, and the insulation resistance>1012.cm, ensuring that the SOC estimation error of the BMS high-voltage sampling circuit is <1%.
III. Lightweight and mechanical reliability
1. Low density and high strength
The density of the silicon nitride substrate is only 3.2 g/cm³ (steel is 7.8g/cm³), and the bending strength is>800MPa, which reduces the weight by 40% at the same strength.
Zirconia toughened ceramic (ZTA) has a bending strength>1200MPa and withstands 50g shock vibration (IEC 60068-2-27 standard), which is used in laser radar protective housings.
2. Thermal shock and corrosion resistance
AlN substrate supports 3000 thermal cycles (-40℃200℃) without interface delamination, and has a lifespan of >15 years.
Surface hardness >15GPa (Vickers hardness), acid and alkali corrosion resistance (salt spray test >1000 hours without failure), suitable for chassis electronic modules.
IV. Technology evolution and future direction
Material upgrade: Silicon nitride AMB substrate gradually replaces AlN, and the thermal conductivity of diamond copper substrate (DBC) exceeds 2000W/m·K, which is suitable for 15 kW/cm heat dissipation limit.
Process innovation: Laser activated metallization (LAM) technology achieves 5μm line width accuracy, and the wiring density is increased by 5 times to meet the high-frequency requirements of GaN.
In summary, semiconductor ceramic shells and substrates promote the upgrading of new energy vehicles to high voltage, high integration and intelligence through breakthrough technical indicators such as ultra-high thermal conductivity, high-density integration, lightweight strength and environmental tolerance.
