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.