The Reliability of Thermoelectric Coolers in Thermal Cycling Process (I)

It can be seen as the reliability test for TECs to make continuous thermal cycling to TECs in a wide temperature rang. Especially temperature of TECs in this process rises to very high. Compared with most applications, this process will cause higher failure rate. Most of failures are rooted in unmatched thermal expansion coefficients of thermal materials and other components. This is inevitable. It performs as initial failure, but sometimes, performance degeneration will be observed before failure.

In order to research the influence of thermal cycling to TECs, we need to define thermal cycling first. In most applications, many thermoelectric components are suffering periodic temperature rise and fall, which may be in a wide temperature range. Although the boundary between cycling and non cycling working conditions is not obvious, but in general, we define thermal cycling as a working condition, under which temperature rises and falls continuously and regularly in a very long time. This condition generally refers to auto temperature control or mechanical temperature control, not manually control. If there are only several cycles of temperature rise and fall, we don’t call it thermal cycling.
The failure rate in thermal cycling is related at least four factors: 1. The total cycling times; 2. The total temperature change range in thermal cycling; 3. The upper temperature limit; 4. The speed rate of temperature change.
To be continued…

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