Insulating AlN: High-Dielectric Aluminum Nitride Ceramics Combining >10¹⁴ Ω·cm Volume Resistivity with Rapid 170–200 W/(m·K) Thermal Dissipation
Insulating AlN (Aluminum Nitride) represents the premier technical ceramic engineered to eliminate galvanic leakage currents and dielectric breakdown across high-voltage, high-power-density electronic hardware. In conventional engineering ceramics, exceptional electrical isolation (such as in Al₂O₃) is fundamentally constrained by low thermal dissipation, while alternative high-conduction insulators like Beryllium Oxide (BeO) carry severe toxicity and regulatory restrictions. Insulating AlN achieves an optimal hexagonal wurtzite crystal structure through precise rare-earth liquid-phase sintering and ultra-low lattice oxygen control. This yields a volume resistivity exceeding 10¹⁴ Ω·cm at 25°C, high dielectric strength (15–20 kV/mm), and low dielectric loss (tan δ < 5 × 10⁻⁴ at 1 MHz). Simultaneously, its ballistic phonon transport delivers a bulk thermal conductivity of 170–200 W/(m·K). With a low coefficient of thermal expansion (4.3–4.6 × 10⁻⁶/K) closely matching Si, SiC, and GaN dies, Insulating AlN prevents interface fatigue and voltage flashing under severe thermal-electrical cycling.
Key Technical Advantages & Core Engineering Value
- Galvanic Isolation & High Breakdown Field: Features a dielectric breakdown strength of 15–20 kV/mm alongside a room-temperature volume resistivity exceeding 10¹⁴ Ω·cm, arresting parasitic leakage currents, partial discharge, and micro-arcing across kilovolt-class high-voltage circuits.
- Dual-Action Dielectric & Phonon Heat Conduction: Resolves the thermal-electrical trade-off by combining high-voltage insulation with 170–200 W/(m·K) bulk thermal conductivity—conducting heat away from critical junctions 7 to 8 times faster than standard 96% alumina ceramics.
- Low-Loss High-Frequency Dielectric Stability: Maintains a stable dielectric constant (εr ≈ 8.6–8.9 at 1 MHz/10 GHz) and an ultra-low loss tangent (tan δ < 5.0 × 10⁻⁴), suppressing capacitive cross-talk, skin-effect dielectric heating, and RF signal distortion in high-speed microelectronics.
- Refractory Hardness & Precision CTE Matching: Delivers a Vickers hardness of HV10 1,100–1,200 and Young’s modulus of 310–330 GPa, combined with a thermal expansion coefficient (4.3–4.6 × 10⁻⁶/K) matched to Si/SiC bare dies to resist cyclic thermomechanical shear stresses.
- Corrosion Immunity & Chemical Stability: Completely non-reactive to corrosive fluorine/chlorine processing plasmas and molten non-ferrous alloys; chemically unreactive with zero toxic degradation, serving as a non-hazardous, fully compliant BeO replacement.
Quantitative Material Specification Sheet
| Dielectric / Physical / Thermal Property | Test Standard | Unit | Typical Value (Insulating AlN) |
|---|---|---|---|
| Chemical Phase / Purity | XRF / Inert Gas Fusion | wt% | AlN ≥ 95.5% (Bound Oxygen < 0.8 wt%) + Y₂O₃ |
| Bulk Density | ASTM C373 / ISO 18754 | g/cm³ | 3.30 – 3.33 |
| Volume Resistivity (25°C) | ASTM D257 | Ω·cm | > 10¹⁴ |
| Volume Resistivity (Elevated, 300°C) | ASTM D257 | Ω·cm | > 10¹¹ |
| Dielectric Breakdown Strength | IEC 60243-1 / ASTM D149 | kV/mm | 15 – 20 |
| Dielectric Constant (εr at 1 MHz) | ASTM D150 | — | 8.6 – 8.9 |
| Dielectric Loss Tangent (tan δ at 1 MHz) | ASTM D150 | — | < 5.0 × 10⁻⁴ |
| Thermal Conductivity (25°C) | ASTM E1461 (Laser Flash) | W/(m·K) | 170 – 200 |
| Coefficient of Thermal Expansion (20–400°C) | ASTM E228 (Dilatometry) | 10⁻⁶/K | 4.3 – 4.6 |
| Flexural Strength (Room Temp, 25°C) | ASTM C1161 (3-Point/4-Point) | MPa | 350 – 420 |
| Fracture Toughness (K₁_C_) | ASTM C1421 (SEPB) | MPa·m¹/² | 2.8 – 3.2 |
| Young’s Modulus (Elastic Modulus) | ASTM C1259 | GPa | 310 – 330 |
| Vickers Hardness (HV1) | ASTM C1327 | GPa / HV | 11.0 – 12.0 (1,100 – 1,200 HV) |
| Max. Continuous Operating Temp (Inert) | Vacuum / Dry N₂ Exposure | °C | 1,600 |
| Max. Continuous Operating Temp (Air) | Oxidation Limit | °C | 700 (Forms protective self-passivating Al₂O₃ film) |
