Reliability

This test is performed according to MIL-STD-883L, method 2002.5, condition A/B.

The objective of this test is to evaluate the product endurance to single mechanical impacts.

During the test, TECs are rigidly mounted on a special table and subjected to five repeated impacts in each of six directions: X1, X2, Y1, Y2, Z1, and Z2 (a total of 30 impacts). For TECs, the Telcordia GR-468-CORE standard recommends using condition A, characterized by a peak acceleration of 500g and a pulse duration of 1.0 ms.  To accurately simulate operating conditions, Telcordia GR-468-CORE also recommends attaching a mass equivalent to the operating mass to the TEC’s cold side during mechanical shock and vibration testing. However, more severe test conditions are allowed to compensate for the absence of the attached mass. For example, condition B of the mechanical shock method can be substituted for condition A, as recommended by Telcordia GR-468-CORE.

This test conforms to MIL-STD-883L, method 2007.3A.

The objective of this method is to evaluate the product’s endurance under a variable frequency sequence within a specified frequency range.

During the test, TECs are rigidly mounted on a specialized vibrating table and subjected to a sine wave vibration with a swept frequency. The vibration frequency is varied logarithmically across a range from 20 to 2,000 Hz. A complete sweep from 20 to 2,000 Hz and back to 20 Hz must be performed in no less than 4 minutes. This cycle must be repeated at least four times in each of the X, Y, and Z directions (for a total of 12 cycles). The peak acceleration is 20 g.

This test method is defined in MIL-STD-883L, method 2019.10.

The purpose of this test is to evaluate a product’s mechanical strength. The test involves measuring the maximum shear force the product can withstand before failure or verifying its serviceability after withstanding specified force levels.

For TECs, this method can be applied as follows: The TEC must, at a minimum, withstand a shear force of 1.0X. Subsequently, the testing should be repeated at increased force levels of 1.25X and 2.0X. If the TEC fails at either 1.25X or 2.0X, a microscopic visual inspection of the failure mode is required.

The Telcordia GR-468-CORE standard mandates this high-temperature storage test for TECs, although it does not reference a specific method within the MIL-STD-883L standard.

The purpose of this test is to determine the TEC’s endurance at an elevated ambient temperature. The specified temperature and storage duration are 85°C and 2000 hours, respectively. Following the test, TECs must undergo visual inspection and serviceability verification using the criteria outlined in the acceptance tests.

These tests conform to MIL-STD-883L, method 1010.

The purpose of these tests is to evaluate the product’s endurance to high and low temperatures, as well as to abrupt transitions between these temperatures.

Test samples are placed within a specialized environmental chamber featuring separate cold and hot zones. Each test cycle involves holding the samples at a specified temperature in one zone, rapidly transferring them to the other zone, and then holding them at the new temperature. The soak time in each zone must be no less than 10 minutes, and the transfer time must be no more than 1 minute.

Following the test, TECs must undergo visual inspection and serviceability verification using the acceptance test criteria.

The TEC qualification test plan outlined in Telcordia GR-468-CORE specifies temperature values of -40°C for the cold zone and +85°C for the hot zone. The number of cycles must be either 100 or 500.

The purpose of this test is to verify the compliance of the TEC’s electrical and thermal parameters—maximum current (Imax), maximum voltage (Umax), maximum cooling capacity (Qmax), and maximum temperature difference (ΔTmax)—with the calculated values specified in the RMT catalog. The detailed methodology is documented in technical specification (ТУ) 27.90.11-001-68694362-2020.

For TEC qualification, the Telcordia GR-468-CORE standard mandates a power cycling reliability test at an elevated temperature—specifically, an intermittent life test—which is described in MIL-STD-883K, method 1006.

The purpose of this test is to verify the reliability of TECs when subjected to a cyclic power supply.

The TEC’s hot side temperature must be maintained at a minimum of 85°C, which corresponds to the maximum temperature of the TEC’s long-term operation. During the “On” phase, the TEC is exposed to its maximum current (Imax). Each cycle consists of a 1.5-minute “On” period and a 4.5-minute “Off” period, with a total of 5000 such “On/Off” cycles.

These tests are conducted according to MIL-STD-883L, method 2004.7, condition D.

The purpose of this test is to evaluate the tensile strength of the connections between the leading wires and the TEC.

A force of 2.22 N is applied perpendicular to the ceramic substrate to the leading wires of the TEC. The test is considered failed if any leading wire is torn or if any metal junction, to which a leading wire is soldered, is partially or completely detached from the ceramic substrate.

While Telcordia GR-468-CORE does not specify this test, it is described in MIL-STD-883L, method 1003.

The purpose of this test is to verify the electrical insulation of the TEC’s internal circuitry from the external surfaces of its substrates.

The testing procedure is as follows: The TEC is connected to a megohmmeter, with one terminal of the megohmmeter attached to a TEC electrical terminal and the other terminal, in turn, attached to the heat-absorbing and heat-rejecting surfaces of the TEC. A DC voltage of not less than 100 V is then applied.

The TEC passes the test if the insulation resistance is not less than 500 MΩ.