A thermal cycling test is a form of environmental simulation. The assemblies are cyclically heated to a high temperature and then cooled to a low temperature. The parameters of this test are the two temperature limits (e.g. -40/+125°C), the speed of the temperature change (fast-schock or slow), the holding time at the temperature limits and the number of cycles. The test is intended to simulate accelerated ageing of the assemblies. The results make it possible to predict service life and analyse reliability.