The Pressure Assisted Densification (PAD) Aluminum Nitride (AlN) is processed to be fully dense, and is characterized as having good thermal conductivity, controlled electrical resistivity and a high dielectric constant. BAE Systems manufactures five grades of AIN to a diameter of 600mm for a variety of different applications especially in the semiconductor industry.
AlN is non-toxic and makes an attractive alternate for applications where beryllium oxide (BeO) is used/considered. Additionally, AlN is resistant to molten aluminum, gallium, iron, nickel, molybdenum, silicon fluorine and boron. The following chart lists typical properties:
| Grade of "PAD" AlN |
Armor |
SC-1 |
HP |
HTC |
|
| Bulk Density (min) |
g/cm^3 |
3.25 |
3.25 |
3.25 | 3.30 |
| Average Grain Size |
μm |
5-8 | 2 - 5 | 2- 5 | 4 - 6 |
| Flexural Strength, (4-Pt. MOR) | Ksi | 45 | 61 | 57 | 70 |
| @RT | MPa | 310 | 380 | 420 | 420 |
| Characteristic stength | MPa | 325 | 420 | 440 | 440 |
| Weibull Modulus (m) | 11 | 12 | 12 | 12 | |
| Elastic Modulus (E) | GPa | 330 | 330 | 330 | 330 |
| Poisson's Ratio (n) | 0.24 | 0.23 | 0.23 | 0.23 | |
| Hardness (Knoop 0.3 kg) | kg/mm^2 | 1100 | 1100 | 1150 | 1100 |
| Fracture Toughness (Chevron Notch) | MPa-m^1/2 | 3.0 | 2.8 | 2.9 | 3.3 |
| Thermal Expansion (RT-1000°C) | 10^-6/°C | 5.2 | 5.0 | 5.5 | 5.5 |
| Thermal Conductivity @RT | (W/m-K) | 80 min. | 80 min. | 80 min. | 150 - 170 |
| Dielectric Constant | 1MHz | 9 | 9 | 8.5 | - |
|
Loss Tangent |
0.00029 |
0.00032 |
0.00049 |
- |
