Multi-stage thermoelectric coolers are required mainly for IR and X-Ray detector applications. Lower operating temperatures provides better sensitivity and reduce noise. Single-stage coolers with max 70-73 degrees of dT (at room conditions) are less required now. Developers and manufacturers are switching for 2- and 3-stage thermoelectric coolers to get deeper cooling level. They need also enough space on the cold side for detector. And it is required to be a compact low power consumption solution, especially for hand-held devices. But for the standard 3-stage coolers with pyramidal shape this is hard to fit all these requirements at once.

Standard multi-stage TECs have pyramidal shape. Each previous stage has to be larger than next one by cooing capacity. It has to pump the heat from the next stage and add additional cooling performance. In most cases it is realized by different numbers of BiTe elements per stage. Briefly, every previous stage has more elements than next one. The pyramidal form is classical and standard for many TE coolers manufacturers. But the pyramidal TEC is not optimal. For example, in case of 4x4mm cold ceramics size, the bottom ceramics is usually about 12x12mm - nine times bigger(!). If customer needs 8x8mm cold side, the dimensions of hot side are out of 20x20mm and so on. TE cooler finally is much bigger than sensitive elements of detector themselves.

New 3MDC TECs have the the same size of top and bottom ceramics. New TECs are assembled with standard and HD pellets placement technology to reduce the size of bottom stages and increase cold ceramics area on the top.

Fig.1 - New 3MDC TECs in comparison with regular typesВ

Fig.2 - New 3MDC TEC on standard TO-8