Thermal Cycling Testing (TCT), or simply thermal cycling or temperature cycling, is a test that determines the capability of supplies to resist very low and really high temperatures. It can be conducted to determine their capacity to resist cyclical exposures to those extreme temperatures.  Any mechanical failure that happens because of the loading of a cyclical thermo-mechanical nature, is known as a fatigue failure, therefore temperature cycling will increase fatigue failure.

Thermal Shock Testing (TST) which is analogous to TCT additionally will increase fatigue failure.
The goal of thermal cycling testing for electrical parts is to seek out out the power of solder interconnects and elements to resist very excessive and low temperatures, and also their capacity to endure repeated exposures to very excessive temperatures. Mechanical stresses induced by heat ends in everlasting changes to the physical or electrical traits of the units being examined. These modifications will compromise their reliability within the short or long term.
Among other things, thermal mismatch of materials can lead to hermetic seal failures, solder joint cracking, and harm to markings and leads.
Cycling charges and other test situations for boards, components, tin whiskers evaluation and/or solder interconnects may be specified. Storing and working temperature limits to be thought-about are those specified by the producer.
Thermal cycling test can also be done on non-polarized elements with very high or low storage temperatures that exceed their operating temperatures. Also, extra temperature ranges can be chosen if the aim of the test is to validate the ability of the components to withstand sure situations which might be beyond their most rating.
The test chamber is provided with the ability to control and supply the specific temperatures within the operating surroundings.
The gadgets under test are subjected to a given variety of thermal cycles to have the ability to evaluate and predict their resistance to effects that are undesirable corresponding to the following:

· Short circuiting of wires in an electrical system

· Fracture or cracking of assemblies or materials because of dimensional changes ensuing from thermal contraction or expansion

· Overheating of assemblies or supplies because of change in heat switch as a result of convection.

After the final cycle is accomplished, the markings will be visually inspected together with different measurements. After the test is concluded, any failure skilled on one or more specific finish-point examinations or measurements, proof of illegible markings, injury or defects to the seals, leads, or case would be thought of a failure.

Thermal cycling test makes use of a temperature cycle chamber to subject the part under test to a selected excessive or low temperature. It then subjects the same unit to a specified low or high temperature for a given variety of cycles.

At the end of the final cycle, exterior visual examination of the seals, leads, and case is completed at 10 X to 20 X. At not more than three X, the marking is then inspected. Any proof of illegible markings, harm or defects to the seals, leads, or case could be thought-about a failure.