Liquid to Liquid Thermal Shock Test

The liquid-to-liquid thermal shock test applies thermal shocks by alternately immersing the samples in a high and low temperature liquid environment. With this method, very high thermal ramp rates can be achieved. It offers much more data than air-to-air thermal shock methods.

The machine used for this protocol has a high temperature reservoir and low temperature reservoir with a mechanical arm and sample basket. The arm is programmed to move at desired intervals, exposing the tested unit to thermal shock, transferring the basket from hot to cold sections. The movement of the sample basket between the rooms is usually done within 10 seconds. This time can also be adjusted as required by the test protocol. The size of the basket is 6 ”x6” x6 ”and special fixtures are available to accommodate strangely shaped items.

Different liquids can be used depending on the application. Anything with high electrical resistance and low surface tension can be used from water, silicone oil or inert fluids developed for thermal shock testing. With this system, a temperature range exceeding -65 to + 150 ° C can be achieved.

Temperature shock testing can help identify physical, chemical, and operating problems for a product. Sudden temperature changes may occur in the field, for example, when moving from an air-conditioned room to a high-temperature desert indoors.

The expansion and contraction caused by temperature changes creates stress from the differences in the expansion rates of the parts made of different bonded materials. Repeated stress causes accumulated fatigue, causing cracks and ruptures. Some examples of physical problems are fragmentation, bonding or cracking of the surface or internal components. This equipment complies with commonly used standards such as MIL-STD-810F, MIL-STD-202, MIL-DTL-38999, TIA / EIA-455-71 and others.