Today, xiaobian continues to explain the knowledge of electronic components. Please see the commonly used screening items of electronic components:
Several commonly used screening items for electronic components
1 High temperature storage
The failure of electronic components is mostly caused by various physical and chemical changes in the body and surface, which are closely related to temperature. As the temperature rises, the chemical reaction speeds up and the failure process accelerates. The defective components can be exposed in time and removed.
High temperature screening is widely used in semiconductor devices, which can effectively remove the devices with surface contamination, poor bonding, defective oxide layer and other failure mechanisms. Usually stored at the highest junction temperature for 24-168 hours.
High temperature screening is simple and inexpensive, and can be implemented on many components. After high temperature storage, the parameter performance of components can be stabilized and parameter drift in use can be reduced. The thermal stress and screening time of various components should be appropriately selected to avoid new failure mechanism.
2 power electric old refining
Screening, under the joint action of thermoelectric stress, can well expose a variety of potential defects inside and on the surface of components, it is an important item of reliability screening.
All kinds of electronic components are usually under the condition of rated power aging for a few hours to 168 hours, some products, such as integrated circuit, can't literally change the condition, but can use high temperature works to improve work junction temperature, achieve high stress state, the various components of the electric stress to choose appropriate, can be equal to or slightly higher than the rated conditions, but it can't attract new failure mechanism. Power aging requires special test equipment, its cost is high, so the screening time should not be too long. Civilian products are usually several hours, military highly reliable products can choose 100.168 hours, aerospace components can choose 240 hours or even longer cycle.
3 Temperature cycle
Electronic products will encounter different ambient temperature conditions in the process of use. Under the stress of thermal expansion and cold contraction, components with poor thermal matching performance are easy to fail. Temperature cycle screening utilizes the thermal expansion and cold contraction stress between extreme high temperature and extreme low temperature, which can effectively eliminate products with thermal property defects. The commonly used screening conditions for components are -55 ~ +125℃, cycle 5 ~ 10 times.
4 Centrifugal acceleration
Centrifugal acceleration test is also known as constant stress acceleration test. This screening is usually carried out on semiconductor devices, the use of centrifugal force generated by high-speed rotation on the device, can eliminate the weak bond strength, the internal lead matching is not good and bad installation of the device, usually choose 20000g centrifugal acceleration test for one minute.
5 Monitor vibration and impact
Monitoring the electrical properties of a product during vibration or impact testing is often referred to as monitored vibration or monitored impact testing. This test can simulate the vibration and impact environment in the process of using the product, and can effectively eliminate the components with bad mechanical structure such as instantaneous short and circuit break and the faults such as virtual welding in the whole machine. Vibration and shock monitoring is an important screening item in highly reliable relays, connectors and military electronic equipment.
Typical vibration conditions are: frequency 20 ~ 200Hz, acceleration 2~20g, scan 1~2 cycles, stay near the resonance point for a longer period of time. The typical impact screening condition is 1500^-3000g, three to five shocks, this test is only applicable to components.
Monitoring vibration and impact requires special test equipment, which is expensive and generally not used in civil electronic products.
In addition to the above screening items, commonly used leak detection, microscopy, linear discrimination screening, precision screening, etc.