Performance of thermoelectric modules depends on the properties of thermoelectric materials.
To manufacture Peltier modules, Ferrotec Nord applies only high-strength thermoelectric materials produced by the own thermoelectric material production department and using the powder metallurgical technique.
Given below are basic characteristics of Р and N type of thermoelectric materials, depending on the temperature (within 200 — 350 K):
Properties of ceramic substrates for thermoelectric modules
Employed in the thermoelectric module manufacture as a heat-conducting construction material are ceramic substrates of aluminum oxide containing no less than 96% of Al2O3. The standard substrate thickness ranges from 0.5 to 0.8 mm depending on the module design and geometry.
Today aluminum nitride ceramics with higher thermal conductivity and a lower thermal expansion coefficient is gaining acceptance.
Properties of Al2O3 ceramic vs AlN ceramic
| Properties | Units | Al2O3 ceramic | AlN ceramic |
| Thermal conductivity | W/(m·K) | 32 — 36 | 160 — 180 |
| Heat capacity at constant pressure | J/(kg·K) | 775 | 730 |
| Thermal expansion coefficient | 10-6 /K | 7 — 8 | 4.6 |
| Density | kg/m3 | 3800 | 3300 |
| Electric resistance | Ohm·cm | ›1014 | ›1014 |
| Young’s modulus | GPa | 372 | 331 |
| Hardness (Knoop) | GPa | 14.1 | 11.8 |
| Ceramic color | white | grey |
The above properties are given for 25 °С.
Ceramic substrates of aluminum nitride are most commonly used for the manufacture of thermoelectric modules for telecommunication equipment.