Charpter 1 Air tightness and heat dissipation performance
- Advantages of air tightness technical index
- High chemical stability and corrosion protection
Ceramic materials (alumina, aluminum nitride) exhibit excellent chemical inertness, effectively isolating moisture, oxygen, and other corrosive gases. This prevents the compound semiconductor materials (GaAs, InP) in optical modules from degrading due to oxidation or hydrolysis. Ceramic tube shells, through hermetic encapsulation, can control internal humidity to <5% RH, significantly extending device life.
- Guarantee the air tightness of the multi-layer co-fired ceramics (HTCC) process
Ceramic tube shell adopts HTCC technology to form a dense multi-layer insulation structure through high temperature cofiring, ensuring air tightness packaging and realizing complex circuit interconnection. By optimizing the CPGA structure and integrating with the hot sink block, the ceramic tube shell can not only meet the requirements of high-density electrical connection, but also maintain the air tightness (leakage rate <510 ⁸ atm · cc / s), which is suitable for the long-term stable operation of the high-speed optical module in the AI data center.
- High temperature resistance and heat and impact resistance performance
The thermal expansion coefficient of ceramic materials (AlN 4.510 ⁶ / ℃) is highly matched with the semiconductor chip (SiC 4.010 ⁶ / ℃) to reduce the risk of interfacial stress cracking caused by temperature cycle. Silicon nitride ceramic substrate can still maintain air tightness under high temperature working conditions (> 200℃), which is suitable for extreme environments such as on-board AI chips.
- Heat dissipation performance technical index advantage
- High thermal conductivity material and heat sink design
Aluminum nitride (AlN) and silicon nitride (Si ₃ N ₄): the thermal conductivity of AlN is 170-200 W / (m · K), and the thermal conductivity of Si ₃ N ₄ is 90-120 W / (m · K W) while maintaining high mechanical strength (bending strength> 600 MPa), far more than conventional alumina (24 W / (m · K)). Tesla’s next-generation electric drive system uses a SiC microchannel liquid-cooled substrate, with a heat flow density of 500 W / cm² and a life span of up to 250,000 hours.
Heat sink structure optimization: the ceramic heat sink increases the heat dissipation area through the fin design. Combined with Micro TEC (semiconductor refrigerator) active temperature control technology, the working temperature fluctuation of the optical module chip can be controlled at ± 0.1℃ to ensure the stability of the laser wavelength. Aluminum nitride heat sink can increase the output power of the high-power laser to more than 30W.
- Advanced technology to improve the heat dissipation efficiency
AMB (active metal brazing) technology: through the metallurgical combination of copper layer and ceramic substrate, the interface thermal resistance is reduced by 30%, suitable for the high power packaging of the third generation semiconductor (SiC, GaN). Silicon nitride AMB substrate supports 300A current shock.
Microchannel liquid cooling integration: the ceramic substrate (serpentine / spiral structure) embedded with microflow channel can reduce the thermal resistance by 11.8%, and the heat flow density exceeds 1000 W / cm², meeting the extreme heat dissipation requirements of AI supercomputer chips.
- Structural design and material composite innovation
The new ceramic shell is integrated with heat sink and PIN needle, and the heat dissipation efficiency is improved by 40%, and it also supports high frequency signal transmission (dielectric loss <0.002).
The AlN / SiC composite substrate is combined with microchannel liquid cooling, and the thermal resistance is reduced to 0.8 K / W, which is suitable for high-power laser packaging.
- AI industry application scenarios and cases
- Optical module packaging: ceramic tube shell and carrier plate are used for TOSA / ROSA components of 800G/1.6T optical module to ensure air tightness and achieve efficient heat dissipation.
- GPU and AI chip heat dissipation: after the NVIDIA H100 graphics card using microchannel liquid-cooled ceramic substrate, the power consumption is reduced by 15%, and the space occupation is reduced by 40%.
- On-board AI and autonomous driving: The third generation semiconductor device (SiC MOSFET) adopts silicon nitride AMB substrate, improves the thermal cycle life to more than 3 times of the traditional solution, and supports 800V high voltage platform.
In the AI industry, ceramic tube shells and substrates ensure high reliability and long life through hermetic packaging technology. The combination of high thermal conductivity materials with active cooling solutions addresses the thermal management challenges of high-power devices. With the surge in AI computing demands, the advantages of ceramic materials in hermeticity (HTCC process), heat dissipation performance (AMB/microchannel technology), and high-frequency signal compatibility (low dielectric loss) will further drive their application expansion in optical communications, supercomputing, automotive electronics, and other fields.
Chapter II Performance of mechanical support and electrical connection
- Mechanical support performance advantage
- High strength and bending performance
Silicon nitride (Si ₃ N ₄) ceramic carrier showed extremely high bending strength (650 ± 30 MPa) and fracture toughness (7.1 MPa · m¹ / ²), 117% and 58% improvement than conventional alumina (Al ₂ O ₃) substrate. This feature can resist the mechanical vibration and thermal stress impact generated by the high-speed computing of the AI chip, and it is suitable for high-density packaging scenarios such as the server GPU / TPU.
The compressive strength of ceramic tube shell (HTCC / CQFP) can reach 400 MPa, which can meet the industrial grade seismic demand (20g / 10-2000 Hz random vibration test).
- Matching of the thermal expansion coefficient (CTE)
The difference between silicon nitride substrate (CTE = 3.010 ⁶ / ℃) and SiC / GaN chip (CTE 4.010 ⁶ / ℃) is less than 1.010 ⁶ / ℃, and the interface thermal stress is reduced by 78%, effectively preventing the problem of packaging stratification.
The gradient composite substrate (SiN/AlN laminate) further optimizes the CTE matching, and the warpage is controlled within 10 μm/in to adapt to the micron-level packaging accuracy of AI chips.
- Air tightness and corrosion resistance
The ceramic pipe shell adopts air-tight packaging technology (leakage rate <110 ⁹ Pa · m³ / s), which can block moisture, dust and other environmental erosion, and ensure the long-term reliability of AI chip in high humidity environment such as data center.
- Electrical connection performance advantage
- High frequency signal transmission capability
The DPC (direct electroplating ceramic) substrate supports ultra-fine line width/spacing of 30-50 μm, surface roughness Ra less than or equal to 0.05 μm, and skin effect loss is reduced by 40%, meeting the millimeter-wave signal transmission requirements of 5G/light communication modules (24-71 GHz).
The dielectric loss (tanδ=0.0018@40 GHz) of the silicon nitride substrate was reduced by 55% less than that of alumina (tan δ =0.004), improving the phase consistency of the AI training chip.
- High-density interconnect and 3 D integration
DPC process realizes vertical interconnection through laser punching and plating filling, and supports 3 D stacking packaging, which improves the packaging density of AI chips by more than 3 times.
The AMB (active metal brazing) process combined with silicon nitride substrate, copper layer thickness of more than 200 μ m, supports high current (600A) transmission, and adapted to the high power requirements of the AI server power module.
- High pressure resistance and insulation performance
Aluminum nitride (AlN) carrier plate has a dielectric strength of 20 kV / mm, the breakdown voltage is 5 times that of plastic packaging, and it is suitable for the power management unit (PMIC) of AI acceleration card.
The low dielectric constant of the ceramic tube shell (εᵣ =9.2@60 GHz) reduces the signal delay and improves the parallel computing efficiency of the neural network chip.
- Synergy advantage of thermal management performance
- High thermal conductivity heat dissipation
The thermal conductivity of aluminum nitride (AlN) substrate reaches 170-200 W / m · K, which can reduce the junction temperature of AI chip by 35% and support the kilowatt-level liquid cooling system.
The silicon nitride (Si ₃ N ₄) substrate achieves a thermal resistance of 0.15 K · mm / W through the AMB process to withstand 5000A / 2ms transient current in the 800V EV AI controller.
- Resistance to thermal shock performance
The critical temperature difference of silicon nitride substrate Δ T ₜ> 800℃, achieving> 8000 no layering in-55℃ to 175℃ extreme cycle, matching the outdoor deployment requirements of AI edge computing equipment.
- Typical scenarios for AI industry applications
Data center GPU packaging: use Si ₃ N ₄ -AMB carrier board, support 50 kW / L power density, and improve the heat dissipation efficiency by 30%.
Autonomous driving chip: CQFN ceramic tube shell (CTE=3.2 x 10⁻⁶/℃) ensures the integrity of lidar signals and passes ISO 16750-3 automotive vibration test.
Optical communication module: DPC ceramic carrier plate achieves 30 μ m wire width wiring and supports high-speed interconnection of 400G / 800G optical module.
Semiconductor ceramic tube shell and carrier plate form a technical closed loop in the three dimensions of mechanical strength, high-frequency electrical performance and thermal management through material innovation (AlN, Si₃N₄) and process upgrading (DPC, AMB), which become the core support for high computing power and high reliability of AI hardware.
Chapter 3: Breakthrough Innovation
- Ceramic pipe and shell: a breakthrough of high integration and efficient heat dissipation
Multi-layer ceramic technology: Through the design of multi-layer ceramic insulation structure, CPGA shell provides electrical signal transmission channel and air tightness protection for optical modules and AI chips. Using the structure of PIN needle and heat sink, the internal heat can be quickly transmitted to the outside through heat sink, and the heat dissipation efficiency is increased by more than 30%. It is suitable for high power scenarios of 800G/1.6T optical module and AI server.
Material optimization: Aluminum nitride (AlN) and beryllium oxide (BeO) ceramics become the preferred materials for heat sink due to their high thermal conductivity (AlN: 170-230 W / m · K), which significantly reduces the working temperature of the optical module and extends the life of the laser. At the same time, the bending strength of the ceramic casing (> 700 MPa Al₂O₃ ceramic) and low thermal expansion coefficient (matching the chip) reduce the risk of packaging failure due to thermal stress.
Application scenario: Support AI data center liquid cooling technology, fit butterfly packaging (BOX) and coaxial packaging (TO-CAN), and meet the strict requirements of 400G / 800G optical module for air tightness and high-frequency signal integrity.
- AMB (active metal brazing) ceramic substrate: the innovation of high power heat dissipation
Material characteristics: The AMB substrate adopts silicon nitride (Si ₃ N ₄) or aluminum nitride (AlN) ceramics, and realizes the high strength combination of copper layer and ceramic through the active metal brazing process. Its thermal conductivity can reach 200 W / m · K (AlN), and its dielectric strength is> 20 kV / mm. It is suitable for high power devices such as high temperature of IGBT and lidar.
Technical advantages: Compared with the traditional DBC (direct copper clad) substrate, the copper layer thickness of AMB is more uniform (± 5 μ m), the interface cavity rate is <1%, improve the current carrying capacity (> 300 A / cm²) and heat resistance cycle capacity (> 5000 cycles), to meet the needs of new energy vehicles and AI servers.
AI scenario adaptation: In the power management module of the AI training cluster, the AMB substrate supports the packaging of silicon carbide (SiC) power devices, reduces energy consumption and improves the switching frequency, and helps optimize the energy efficiency of the data center.
- FCBGA loading board: high density interconnection and signal integrity improvement
Structural design: FCBGA board adopts the composite structure of ceramic substrate (Al ₂ O ₃ or AlN) and copper layer. The dielectric loss of core plate is <0.004, and the insertion loss is reduced by 30%. It is suitable for high-speed data transmission of 112 Gbps (> CPU / GPU).
Heat dissipation optimization: Through the design of embedded copper column and microporous arrays, the thermal resistance is reduced to 0.15°C · cm² / W, which supports the continuous high load operation of AI reasoning chip (NVIDIA H100).
Process innovation: FCBGA technology combines thin film deposition and laser drilling process to realize the line width / wire spacing of 10 μ m, the welding ball density of> 5000 / cm², and meet the high-density interconnection requirements of AI chip packaging.
- High surface finish of alumina ceramic substrate: the core of precision manufacturing
Material purity and processing: 4N grade high purity alumina (purity> 99.99%) through nano powder wet chemical synthesis and discharge plasma sintering (SPS), surface roughness Ra <0.01 μ m, dielectric loss (tan δ) <210 ⁴ (@10 GHz), suitable for high frequency microwave substrate and wafer polishing.
application scenarios:
Semiconductor equipment: used for plasma etching cavity coating and electrostatic suction cup (ESC), high temperature resistance (> 1600℃) and plasma corrosion resistance, improve the yield of chip manufacturing.
AI chip packaging: high finish surface reduces signal reflection loss, combined with film metallization (Ti / Pt / Au), to achieve low insertion loss of microwave circuit (<0.1 dB / mm) transmission.
Summary: The advantage comparison of technical indicators
| technology | Core indicators | AI industry application scenarios |
| Ceramic tube shell | Thermal conductivity> 170 W / m · K, air tightness of 110 ⁸ Pa · m³ / s, and flexural strength> 400 MPa | Optical module packaging, AI server chip heat dissipation |
| AMB basilar plate | Thermal conductivity 200 W / m · K, copper layer binding strength> 30 MPa, and thermal cycle life> 5000 times | IGBT, lidar, data center power module |
| FCBGA support plate | Dielectric loss <0.004, welded ball density> 5000 cells / cm², and signal rate> 112 Gbps | GPU / CPU package, autonomous driving computing unit |
| High ized alumina substrate | Surface roughness Ra <0.01 μ m, permittivity ε =9.8@10 GHz, and flexural strength> 800 MPa | High-frequency microwave circuit, wafer polishing, semiconductor equipment components |
Innovation not only solves the problem of heat dissipation and reliability of AI hardware under high frequency, high power and high integration, but also enables the evolution of AI computing infrastructure to higher performance and energy efficiency through the synergistic optimization of materials and processes.
