Aluminium Oxide Al₂O₃ - Substrates
Aluminium oxide (Al₂O₃) substrates are high-quality ceramic circuit carriers with a wide range of applications. They serve as electrical insulators while simultaneously acting as a stable mechanical support - whether for DCB metallization in power modules within power electronics, or for hybrid circuits and demanding thick-film and thin-film circuits in microelectronics. They are the backbone of modern high-performance electronics in industry, vehicle electrification, and renewable energies.
They impress with an outstanding price-to-performance ratio as well as excellent thermal conductivity. CeramTec develops and manufactures Al₂O₃ substrates under the brand name Rubalit® - a globally recognized quality benchmark among manufacturers of DCB-metallized power electronics and hybrid integrated circuits (HICs).
Key Facts at a Glance
- Rubalit® Al₂O₃ substrates have been setting global quality standards for hybrid circuit manufacturers for decades.
- CeramTec's aluminium oxide substrates achieve a flexural strength of 500 MPa and a thermal conductivity of 24 W/mK - with a dielectric strength of 15 kV/mm.
- Fields of application include power electronics for electric vehicles, renewable energies, AI data centers, and industrial applications.
- In microelectronics, they are found in 5G infrastructure, high-frequency technology, as well as thick-film and thin-film technology.
- Various purity grades available: 96 % (708 S), 96 % HP (708 HP), 98 % (798), and 99.6 % (710) - for standard applications through to ultra-thin-film technology.
What variants of Al₂O₃ substrates are available?
Rubalit® 708 HP and 708 S – 96 % Al₂O₃ (High Performance for DCB)
Suitable for: Hybrid circuits, thick-film technology, general power electronics, Direct Copper Bonding (DCB), and assemblies subject to high thermal stress. Rubalit® 708 HP is particularly well-suited for power modules in frequency converters, inverters for photovoltaics and electromobility, delivering consistent reliability even under extreme thermal and electrical loads.
- Outstanding mechanical properties: Exceptionally high flexural strength, good fracture toughness, as well as high thermal cycling capability and thermal shock resistance
- Optimal heat dissipation: High thermal conductivity
- Excellent surface quality: Defined surface on both sides - compatible with all commercial thick-film pastes and suitable for thin-film applications (e.g. sputtering)
Rubalit® 798 – 98 % Al₂O₃ (Enhanced Purity)
Suitable for: Applications with increased requirements for electrical insulation and mechanical stability.
- Optimal balance of improved electrical properties (dielectric loss factor / dielectric constant), thermal conductivity, and high mechanical stability
- For applications that exceed standard requirements or require a further increased aluminium oxide content
- Used in high-frequency and high-voltage electronics
Rubalit® 710 – 99,6 % Al₂O₃ (Highest Purity for Thin-Film Technology)
Suitable for: Thin-film technology, high-frequency electronics, precision sensors.
- Extremely fine surface for the highest demands in thin-film technology
- Particularly low surface roughness (Ra)
- Ideal for sputtered metal layers and laser structuring
What advantages do Al₂O₃ substrates offer compared to other substrate materials?
- Cost efficiency: CeramTec's Al₂O₃ substrates (Rubalit®) offer an outstanding price-to-performance ratio
- Proven reliability: Quality standard among all leading HIC manufacturers worldwide
- Broad processability: Compatible with all commercial thick-film pastes as well as many thin-film / sputtering applications
- Surface quality on both sides: Excellent Ra values for precise coating processes
- High strength: 500 MPa flexural strength for robust electronic assemblies
- Good thermal conductivity: 24 W/mK for reliable thermal management in compact assemblies
- Electrical insulation: 15 kV/mm dielectric strength
Recommendation: For most hybrid circuits and standard power modules, Rubalit® 708 S/HP is the most economical and technically superior choice.
