A temperature cycling test chamber, or thermal cycling chamber, is a test chamber used for temperature and humidity testing with a large compressor that allows the chamber to achieve temperature changes at rates that can vary from 5 – 25 °C per minute and beyond. Temperature cycling test chambers are ideal for test applications that require quick, uniform and reproducible changes in temperature. With a thermal cycling test chamber, operators can simulate the ability of the test subject to withstand temperature extremes as well as cyclical exposures to temperature extremes. Like thermal shock testing, temperature cycling induces fatigue failures that a traditional temp./humidity chamber can’t replicate.
Temperature Cycling Test Procedure
Thermal cycling tests consist of many cycles of low temperature to high temperature conditions. Once the final cycle is complete, the operator will perform a visual examination of the leads, case and seals at 10x to 20x, and the marking examined at no more than 3x. Damage of any sort means the test is a failure; the test subject must be examined for physical damage, like package & die cracking, wire breaks and bond lifts, along with electrical damage if the item under test is electronic.
Temperature Cycle Test Standards
Common temperature cycling test standards include MIL-STD-883 Method 1010 and JESD22-A104D.
MIL-STD-883, Method 1010 Test Specifications
- Transfer Time: ≤ 1 min.
- Dwell Time: ≥ 10 min.
- Chosen Temp. Achieved In: ≤ 15 min.
- Minimum Cycles: 10
JEDEC JESD22-A104 Test Specifications
- Transfer Time: ≤ 1 min.
- Dwell Time: ≥ 10 min.
- Chosen Temp. Achieved In: ≤ 15 min.
- Cycles Needed for Qualification: 1000
Other Thermal Cycling Standards
- GR-468-CORE
- MIL-STD-750 Method 1051
- MIL-STD-750 Method 1055
- MIL-STD-883 Method 1007
- JESD22-A105
Choosing the Right Thermal Cycle Test Chamber
Environmental test personnel looking to rent a temperature cycling chamber should look at the temperature range of the chamber, the chamber’s dimensions, and the temp. cycling rate, cross referencing these with one’s own application and test standards they want to fulfill. Modern temperature cycling test chambers may also have features like a heating/cooling liquid that allows them to cycle at a rate of 25 °C per minute and beyond, the ability to get a high accuracy reading of the temperature of the specimen itself by means of an internal sensor, and high speed controllers. Some temperature and humidity chambers can also be re-purposed for temperature cycling by boosting the strength of the unit’s processor.