Components are the basis of the whole machine. Failures related to time or stress during use may result from inherent defects in the manufacturing process or from improper control of the manufacturing process.
In order to ensure the reliability of the whole batch of components and meet the requirements of the whole machine, it is necessary to exclude the components that may have initial failures under the conditions of use. The process of component failure rate over time can be described by a failure rate curve similar to the "bathtub curve". The early failure rate decreases rapidly with time. The failure rate is essentially constant over the service life (or period of unexpected failures).
1. The high-low Temperature Test Chamber is used for high temperature storage
Most of the failures of electronic components are caused by various physical and chemical changes in the body and surface, which are closely related to temperature. After the temperature rises, the chemical reaction speed is greatly accelerated, and the failure process is also accelerated. Defective components can be exposed and eliminated in time.
High-temperature screening is widely used in semiconductor devices, which can effectively remove devices with failure mechanisms such as surface contamination, poor adhesion, and oxide layer defects. Typically stored at maximum junction temperature for 24 to 168 hours.
High temperature screening is simple, inexpensive, and achievable on many components. After high-temperature storage, the parameter performance of the component can be stabilized, and the parameter drift in use can be reduced. The thermal stress and screening time of the various components should be chosen correctly to avoid new failure mechanisms.
2. The high-low Temperature Test Chamber is used to screen power supply and electrical aging
During the screening process, under the joint action of thermoelectric stress, various potential defects on the surface of the body and components can be well exposed, which is an important item in reliability screening.
Various electronic components are usually aged for several hours to 168 hours under rated power conditions. Some products, such as integrated circuits, cannot change the conditions at will, but can use high-temperature working methods to increase the working junction temperature and reach a high-stress state. The electrical stress of the components should be properly chosen to be equal to or slightly higher than the rated conditions, but not to introduce new failure mechanisms.
Power aging requires special test equipment, which is expensive, so the screening time should not be too long. Civilian products are usually several hours, military high-reliability products can choose 100, 168 hours, and aerospace-grade components can choose 240 hours or even longer periods.
3. Temperature cycle of high-low Temperature Test Chamber
Electronic products will encounter different ambient temperature conditions during use. Under the stress of thermal expansion and contraction, components with poor thermal matching performance are prone to failure. Temperature cycle screening utilizes thermal expansion and contraction stress between extreme high temperature and extremely low temperature, which can effectively eliminate products with thermal performance defects. The commonly used screening conditions for components are -55°C~+125°C, with 5~10 cycles.
