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DBC stands for Direct Bonded Copper, the technology developed for the direct bonding of ceramic substrates with thick copper foils (without any additional interlayer material). This technique can also be applied for the mutual bonding of copper foils.
Typical DBC products are:
1- Power Circuits Substrates
2- Liquid Coolers
1. DBC Substrates
DBC substrates consist of a ceramic insulating layer, typically Alumina (Al2O3) or Aluminium Nitride (AlN) to which pure Copper (Cu-OFE: 99.99%), in the form of rolled foil, is applied in a high temperature melting and diffusion process. The result is a non-detachable connection between copper and ceramics. Today these substrates are the most popular for Chip On Board assembly in power electronics circuits.
The usage of a ceramic layer as electric insulator assures outstanding and stable functional properties (electrical insulation, thermal dissipation).
Specifically ceramic materials will provide the following advantages with respect organic insulators:
- high Thermal Conductivity (Al2O3: 24 W/m·K; AlN: 130-180 W/m·K);
- stable physical and thermo-mechanical properties.
Due to its high thermal conductivity, the ceramic layer can be designed in a thickness range (0.32 – 1.0 mm) able to withstand the highest voltages (Dielectric Strength: > 20 kVdc/mm).
On the other end the usage of thick copper based rolled foils (0.2 – 0.6 mm) provides:
- remarkable current carrying capability (100 – 1,000 Amps);
- great heat spreading and heat capacity à enhanced static and dynamic thermal dissipation.
The excellent adhesion assured by the direct bonding technique makes the Coefficient of Thermal Expansion (CTE) on top of the copper layer very close to the that one of the ceramic layer (Al2O3: 6.8 ppm/K @ 20-300°C; AlN: 4.7 ppm/K @ 20-300°C), which closely matches that of silicon.
2. DBC Liquid Coolers
The DBC copper cooler consists of several layers of pure copper with very fine structures.
These layers are put together into a hermetically tight block by the same direct bonding process used to build DBC substrates (DBC process). During the DBC process, the different layers are connected to each other. The advantage of this process is that no additional soldering or adhesive layers negatively influence the cooler‘s thermal resistance.
Applications
DBC substrates and coolers are typically used to build power modules in several application fields, where high performances and reliability are key requirements.
Typical application fields are:
- Industrial Automation;
- Automotive;
- Railway Traction;
- Aerospace;
- IT & Telecom;
- Medical;
- Renewables Energies;
- Concentration Photovoltaics(CPV);
- White Goods.
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