Burn-in is the process where marginal or accelerated thermal and electrical stresses are applied to semiconductor components for extended periods. The technique is used to ensure reliability, functionality of the devices and products, and detect probable failures arising from manufacturing defects.
When testing a population of a certain component, all the components are exposed to the elevated conditions for a predetermined time. The components that survive are considered appropriate and ready for shipping while the faulty components are discarded. The burn-in is useful in detecting components that would fail at the early failure stage in the bathtub curve. The Component failures are classified by the position on the bathtub curve below
- Early failure stage – highest failure rate
- Random Failure Stage – medium
- Wear-out Failure Stage- high rate
Burn-in may be done on the whole system to test all the building components, instead of the individual component testing. Even though burning in of assembled boards may be difficult due to the different limits of the various components, the test is useful in identifying other faults such as contact problems associated with cold and dry joints.
Types of burn-in processes
- Dynamic burn-in:- the device is exposed to high voltage and temperature extremes while being subjected to various input stimuli
- Static burn-in: – the device is exposed to extreme temperatures and voltages but does not have the inputs.
- Burn-in with test:- dynamic test in which device outputs are monitored during the process
Burn in equipment
The burn-in system works by accelerating the aging process of the semiconductor devices. It applies heat and voltage stresses throughout the chamber using the burn-in boards and sockets.
The chamber provides provide a test environment controlled over a wide range of temperature and time settings. It consists of components that heat the chambers and apply testing voltages to the components on the burn-in board.
The burn-in boards provide the interface between the heat generating system and the sockets. These multi-layer boards are connected directly to the system circuitry using a back-plane and are designed to withstand the extreme temperatures.
This forms the interface between the component and the burn in board. The device pins must maintain good electrical contact throughout the burn-in process.
Advantages of burn-in process
- To determine the component’s failure rate and reliability of a system.
- Ensure the semiconductor device provides reliable operation free of faults.
- Determine estimated useful life.
- This helps manufactures to also identify and eliminate the root cause of the failures.
- Identification and elimination of weak and faulty units hence prevent premature equipment failures.