Ceramic Meet Metallization Technology: A New Upgrade in Heat Dissipation for New Energy Vehicles

Driven by the "new four modernizations" trend, the functional density of electronic systems in new energy vehicles is constantly increasing, leading to a corresponding increase in the power consumption of semiconductor chips. Lightweighting and high integration are becoming the main themes of industrial development, while heat dissipation is gradually becoming one of the key bottlenecks affecting the stability and lifespan of electronic devices.

Against this backdrop, ceramic materials, with their high thermal conductivity, insulation, and high reliability, are gradually coming to the forefront and deeply integrating with ceramic metallization technology, becoming an important basic material in the thermal management solutions for new energy vehicles.

Ceramics have become an important packaging material for power devices due to their combination of high thermal conductivity, low dielectric loss, good insulation, high heat resistance, and a thermal expansion coefficient that closely matches the chip. These properties make metallized ceramics, metallized alumina, and metallized alumina ceramics important structural materials for current high-power electronic devices.

Among them, alumina ceramic components such as AlN and Al₂O₃, due to their stable physical properties, are widely used in power modules, LED packaging, relays, and power modules of new energy vehicles. With the continuous improvement of the interface performance between ceramic and metal layers, the penetration rate of metalized ceramics in electric vehicle heat dissipation continues to increase.

While ceramics possess excellent insulation and thermal properties, they are not conductive. To achieve circuit functionality, ceramic metallization is necessary. The metallization layer must not only have good conductivity but also be firmly bonded to the ceramic, withstanding complex conditions such as temperature cycling, mechanical stress, and long-term charge carrying.

The fundamental reason why ceramics and metals are difficult to directly bond is the significant difference in their chemical properties, coefficients of thermal expansion, and wettability. Therefore, the ceramic-to-metal conversion process typically requires the construction of a stable interface structure through metallurgical reactions, interface modulation, or metallization of thin films.

Currently, ceramic metallization mainly falls into two major categories:

1. Solid-state bonding metallization technologies

These include direct copper bonding (DBC), direct aluminum bonding, and thick-film methods. These methods attempt to achieve direct solid-state bonding between ceramics and metals, but the types of metals that can directly react with ceramics are limited, and they typically require harsh conditions such as high temperature and vacuum. In actual production, additional interface conditioning materials are often needed to achieve stable bonding.

2. Thin-film metallization transition layers

Through sputtering, evaporation, and electroless plating, metallized thin films are formed on the ceramic surface to improve wettability and interface structure, preparing for subsequent metal layer deposition and welding. This type of method is widely used in metallized ceramic components, metallized alumina ceramics, and ceramic packaging, and is particularly suitable for high-reliability and precision electronic modules.

1. Thick-film metallization (TPC)

Thick-film technology uses screen printing of conductive paste and high-temperature sintering to form a film. The process is simple and applicable to a variety of metallized ceramic materials. However, the wire path is limited by the precision of the wire mesh, making it suitable for large-sized devices with medium power requirements, but less adaptable to high-precision ceramic packaging or fine alumina ceramic machining.

2. Thin Film Metallization (TFC)

Utilizing vapor deposition techniques such as vacuum sputtering and evaporation, a high-density metal film is formed on the ceramic surface. It boasts strong adhesion, good coverage, and can be used to deposit films of various metal materials. Thin film metallization is particularly suitable for high-density integrated circuits, precision lead structures, and high-reliability metallized ceramics, but its cost is high, requiring subsequent fine processes such as photolithography and etching.

3. Direct Copper Lamination (DBC)

DBC involves reacting copper foil with ceramic at high temperatures to form a strong bond, creating a metal layer with high thermal conductivity and strong adhesion. Its advantages include good thermal conductivity, strong insulation, and superior mechanical properties, making it widely used in power modules and electric vehicle drive systems. However, the relatively thick copper foil limits the precision of subsequent chemical etching, restricting the fabrication of ultra-fine circuits.

4. Active Metal Brazing (AMB)

AMB achieves a high-strength bond between the metal layer and ceramic by reacting a solder containing active elements with the ceramic to form a wettable interface. This technology effectively handles high-temperature stress and is one of the mainstream metallization methods for mid-to-high-end power modules, particularly suitable for high thermal conductivity ceramics such as metallized AlN structures.

5. Co-firing (HTCC/LTCC)

HTCC and LTCC form an integrated structure by co-firing multiple layers of ceramic with internal wiring, making them important technologies for multi-layer ceramic packaging. HTCC applications are reduced due to its high temperature, while LTCC is widely used in high-frequency, high-speed communication and automotive electronic modules due to its low dielectric loss and ability to achieve multi-layer wiring.

6. Chemical Plating Metallization

Chemical plating deposits a metal layer through a chemical reduction process without applied current, making it effective for complex-shaped metallized aluminum and irregular aluminum ceramic machining structures. Its bond strength depends on surface roughness, making it suitable for localized metallization or high-density packaging requirements.

7. Laser Metallization

Laser heating causes thermal decomposition of the AlN surface, directly forming a conductive metal layer. This method is characterized by its simple process, low cost, and high efficiency, making it suitable for the rapid metallization production of some power devices.

1. High-Voltage DC Relays

Vacuum relays using metallized ceramics achieve arc-free switching under high voltage through a ceramic insulation structure, significantly improving reliability and safety. They play a crucial role in preventing thermal runaway caused by electric arcs. The ceramic housing structure is irreplaceable in maintaining insulation, controlling electric arcs, and withstanding electrical shocks.

2. IGBT and SiC MOSFET Power Modules

Ceramic copper-clad substrates (DBC/AMB) are considered a core material for the main drive inverters of new energy vehicles due to their high insulation, high heat dissipation, strong mechanical properties, and excellent thermal expansion matching. AMB, in particular, excels in the bonding strength and reliability of the metal layer and ceramic interface, and has become the mainstream approach for many high-performance power modules.

3. LED Packaging and Automotive Lighting

Most of the energy in LED chips is converted into heat, making high thermal conductivity ceramic substrate, such as AlN ,ideal heat dissipation materials for high-brightness and ultraviolet LEDs. With the continuous increase in the power of automotive lighting systems, metalized ceramics are rapidly penetrating high-power LED modules.

Although there are various metallization methods, differences remain between different processes in terms of cost, bonding strength, production stability, and large-scale manufacturing capabilities. How to construct a strong and tough metal layer on high thermal conductivity ceramics and ensure long-term reliability during high and low temperature cycling is a key direction for future in-depth research into ceramic metallization technology.

High power density, autonomous driving computing platforms, and continuous upgrades to electric drive systems will all drive metalized ceramics, metallized alumina ceramics, ceramic packaging, and precision alumina ceramic machining into a wider range of applications.