The devices became commercially available in the 60’s with the development of advanced semiconductor thermocouple materials in combination with ceramics substrates. Thermoelectric modules (TEMs) are solid-state heat pumps that require a heat exchanger to dissipate heat utilizing the Peltier Effect. During operation, DC current flows through the TEM to create heat transfer and a temperature differential across the ceramic surfaces, causing one side of the TEM to be cold, while the other side is hot. A standard single-stage TEM can achieve temperature differentials of up to 70°C. However, modern growth and processing methods of semiconductor materials are exceeding this limitation.
TEMs have several advantages over alternate cooling technologies. They have no moving parts, so the solid state construction results in high reliability. TEMs can cool devices down to well below ambient. Colder temperatures can be achieved, down to minus 100°C, by using a multistage thermoelectric module in a vacuum environment. Thermoelectrics are able to heat and cool by simply reversing the polarity, which changes the direction of heat transfer. This allows temperature control to be very precise, where up to ±0.01°C can be maintained under steady-state conditions. In heating mode TEMs are much more efficient than conventional resistive heaters because they generate heat from the input power supplied plus additional heat generated by the heat pumping action that occurs.
Thermoelectrics are ideal for applications that require active cooling to below ambient and have cooling capacity requirements of up to 600 Watts. A design engineer should consider them when the system design criteria includes such factors as precise temperature control, high reliability, compact geometry constraints, low weight and environmental requirements. These products are ideal for many of the consumer, food & beverage, medical, telecom, photonics and industrial applications requiring thermal management.