Quality testing of two-stage thermoelectric cascades

The usual practice of quality testing manufactured two-stage thermoelectric modules (TSTMs) is to measure their maximum temperature differential in a high-vacuum system using a temperature-controlled, constant base plate. This is very difficult, time-consuming, expensive and requires sophisticated, complex equipment. As such, it is not practical to assure quality of TSTMs on a 100% basis. Therefore, it is desirable to create a new test method for these TE coolers which shortens test time and minimizes experimental error. This paper describes the development of a new testing method for TSTMs which takes advantage of the transient method developed by Buist [1992] and/or the modified Harman [1962] method developed by Gorodetskiy [1995]. This method basically consists of electrically isolating the bottom and top stages and testing the characteristics of the bottom and top stages individually by auxiliary wires, if needed. The accuracy and validity of this test method was developed by pre-characterizing each stage (prior to TSTM assembly) as individual TE modules. After TSTM assembly, the proposed new test method was applied and compared with component test results. Although the implied “modular” approach to TSTM fabrication was applied to validate results, this new test method applies to all TSTMs if auxiliary wires are either not needed or attachable