Hasn’t chip wars accelerated the conflicts focus on ceramic PCB of AI chip made in China?
With an aggressive trade war with China. The United States imposed a series of economic sanctions on China, focusing on technology and military. Reuters reports the U.S limited the amount of AI chips production in Huawei to no more than 200,000 this year. It is notice that chip wars stands for the power of a country. Of which, AI chip cannot run without ceramic substrates, which are key components of it inside and outside.
There are are four key directions to apply as internal elements.
High Bandwidth Memory (HBM) Ai stack support
High Bandwidth Demands in AI Chips
AI chips require extremely high data transfer rates, and memory bandwidth must meet these demands. Current technologies can exceed 256 GBps while also improving energy efficiency.
2.5D Packaging and TSV Challenges
A key technology is 2.5D packaging, which uses a silicon interposer with Through-Silicon Vias (TSVs). However, this approach is high-cost, mainly due to TSV formation and interposer thinning.
LTCC as a Solution
Low-Temperature Co-fired Ceramic (LTCC) substrates offer an alternative solution:
High temperature resistance
Corrosion and impact strength
More reliable than silicon substrates, reducing throughput loss and decreasing interposer displacement by 1/5
So more reliable than Silicon substrates, conveying the loss of high throughput, reducing 1/5 displacement of interposer board(1). With fine pitch layer LTCC package form thin file based on LTCC substrates. The surface is flat, so it can depict high density wiring. This material also reveals symbol of letting signals pass through with little loss and keep them clear, which makes them a good choice for high-frequency machine (HFD) like 5G and radar.
Multi chip module
What is MCM?
A Multi-Chip Module (MCM) is a packaging technology that integrates multiple small substrates into a large-scale system, enabling high-density integration and compact design. This makes it highly suitable for AI chips and devices such as Bipolar, CMOS, PROM, RAM, and even NVIDIA Cosmos.
MCM Ceramic (MCM Cofired)
MCM Ceramic, also known as MCM Cofired, is one of the main technologies used in MCM packaging. It provides advantages in thermal management, electrical insulation, and mechanical reliability
Types of MCM Ceramic Technologies
MCM Ceramic technologies are generally divided into three categories:
Thick Film Ceramic – used for moderate performance requirements, enabling reliable interconnections.
High Temperature Cofired Ceramic (HTCC) – suitable for applications requiring high thermal stability and mechanical strength.
Low Temperature Cofired Ceramic (LTCC) – supports fine-pitch wiring, multilayer packaging, and high-frequency applications, making it ideal for advanced AI and communication systems.
Radio Frequency(RF) signal system
The material of RF Technology
Signal integrity at RF well in many applications. The use of material of this kind of line signal conductors according to different requirements.The dielectric constant of aluminum nitride ceramic remains relatively stable—around 8.7 to 8.8 in the 140–220 GHz range and approximately 8.83 from 0.2 to 1.0 THz—making it an excellent candidate for freq radio (The dielectric properties of some ceramic printed circuit board materials at terahertz frequencies.
Materials Properties In RF Radio
Thanks to this stability, AlN and similar materials demonstrate reliable performance in various RF technologies scenarios [2]. Depending on design requirements, different ceramic materials can be used for signal conductor lines. Among them, alumina ceramic and HTCC are commonly employed. LTCC and HTCC technologies have also been widely adopted in microwave and 5G and radar systems due to their cost-effectiveness and suitability for massive production.
Technologies Applied In Radio Frequency Products
However, both HTCC and LTCC technologies use unfired ceramic substrates (also known as green sheet) for circuit fabrication, which rely on thick-film coating processes. These printing methods lack the precision required for fine-pitch circuitry and are prone to short circuits during micro-patterning. Furthermore, the printed conductor edges are not as sharply defined as those produced through photolithography, resulting in higher insertion loss.
Additionally, during high-temperature sintering—typically above 1000°C—HTCC and LTCC substrates undergo significant shrinkage. This shrinkage is often non-uniform and difficult to control, which is a critical drawback for high-density interconnection applications.
As a result, HTCC and LTCC processes have largely been eliminated in the manufacturing of next-generation ceramic substrates for chip artificial intelligence. JinRuixin has developed a new ceramic substrate pcb process over the past two years, based on ceramic heat sinking and TEC structures, which effectively support multilayer high-density interconnections, ensure excellent dimensional stability, and meet the stringent thermal management requirements of AI chips…
Co-Packaged Optics (CPO)
Co-Packaged Optics (CPO)
In optical communication area, Co-Packaged Optics is key element of optical communication system, which accelerate the signal and electrical switchover and realizing high data conversion. The AI server optical module needs to be equipped with a high-level differential output oscillator.
Role of Ceramic Packaging
Ceramic package base is widely used in quartz crystal oscillators and quartz crystal resonators,it made of raw ceramic pieces printed with conductive materials and clearance holes [3].
Material Selection
Alumina Ceramic: The most commonly used material for ceramic bases.
Aluminum Nitride (AlN) Ceramic: Provides better thermal conductivity (170–250 W/m·K) and a more favorable coefficient of thermal expansion (CTE) compared to alumina, making it a superior choice for high-performance applications.
Currently, the most widely used AuSn alloy composition is 80% gold and 20% tin, with a typical thickness ranging from 3 to 5 µm
Au-Sn Heat Sink Applications on Aluminum Nitride
Layer Deposition Process
Copper Plating: A 70 µm (2 oz) copper layer is first plated on the ceramic substrate.
Gold Film: A 1 µm (40 µ”) gold film is deposited as a base layer.
Platinum Plating (Bonding Area Only): An additional 0.5 µm (20 µ”) platinum layer is plated in the chip eutectic bonding area.
Au-Sn Alloy Layer: A 3–5 µm (120–200 µ”) Au-Sn alloy is plated to complete the bonding surface.
Substrate Planarity and Structural Requirements
Material: AlN (Aluminum Nitride) substrates.
Planarity: Extremely strict requirements due to precision chip bonding.
Sidewall Verticality: The angle of sidewalls must not exceed 5°, ensuring uniform bonding strength and solder flow.
Advantages of Pre-Deposited AuSn
Provides precision-grade soldering performance.
Ensures reliable interconnects for high-density and high-accuracy chip packaging.
Reduces process variability compared to post-applied solder.
Enhances mechanical stability and thermal reliability of the final package.
External material for AI chip
Thermoelectric Cooler (TEC)
The Function Of Thermoelectric Cooling System
Electronic devices like AI chip generate plenty amount of heat during processing. Owing to solve the issue of ai chip heat dissipation, electric cooler can be used for it. Under most circumstances, The highest temperature electronic junction cannot beyond 85°(Experimental investigation of using thermometric cooling for computer chips). Thermo electric cooler system design used uniform electric current distribution to cool the temperature down, improving cooling efficiency. Which also combined two options of liquid cooling and air cooling emerge great influence, since their high reliability tiny size and Ultra-low noise. Miniature thermoelectric cooler substrates are typically made from aluminum nitride (AlN) ceramic with a thickness of 0.15–0.2 mm (6–8 mil).
The Material Of TEC Cooler
The copper layers used are relatively thin, ranging from 0.8–1.5 mil in thickness. The surface finish is usually ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold), with relatively thick palladium and gold layers (4–7 µ”) to meet the stringent requirements of fine wire bonding on micro pads [4].Soldering of the TEC die is typically done using a SnBi (tin bismuth) alloy, which offers low-temperature bonding in ceramic materials [5]. The planarity and squareness of the bonding pads are critical due to the fine pitch between them, placing high demands on both packaging equipment and process precision.
Conclusion
Ceramic substrates play a crucial role in AI chip performance, from internal memory support to external thermal management. Their unique electrical, thermal, and mechanical properties make them indispensable in next-generation high-frequency, high density, and high power AI systems. As global demand for AI technology rises and geopolitical restrictions tighten, the strategic value of ceramic substrates becomes even more prominent, influencing the future direction of semiconductor manufacturing and supply chain resilience.
