Burn-in Test

Definition: A burn-in test is an accelerated stress test performed on electronic devices, including VLSI circuits, to identify and eliminate early-life failures, also known as infant mortality failures. The test involves subjecting the devices to elevated temperature and voltage conditions for a specified period to accelerate the aging process and reveal latent defects that may cause premature failures during normal operation.

Key Characteristics:

  • Accelerated stress test that subjects devices to elevated temperature and voltage
  • Aims to identify and eliminate early-life failures (infant mortality)
  • Performed before shipping the devices to customers to improve reliability
  • Accelerates the aging process to reveal latent defects and weak components
  • Helps to ensure that the devices shipped to customers have a lower failure rate

Burn-in Test Procedure:

  1. Place the devices in a controlled environment (burn-in chamber) with elevated temperature and voltage conditions
  2. Apply power to the devices and let them operate under the stressed conditions for a specified duration (typically 24 to 168 hours)
  3. Monitor the devices for failures or anomalies during the burn-in period
  4. Remove the failed devices and perform failure analysis to identify the root cause of the failures
  5. Devices that survive the burn-in test are considered to have passed and are ready for shipment

Advantages:

  • Identifies and eliminates early-life failures, improving the reliability of the shipped devices
  • Reduces the infant mortality rate and minimizes the likelihood of early failures in the field
  • Helps to ensure that the devices shipped to customers have a lower failure rate
  • Provides an opportunity to identify and correct design or manufacturing issues before shipping the products
  • Improves customer satisfaction by delivering more reliable products

Limitations:

  • Increased cost and time associated with the burn-in process
  • Potential for over-stressing the devices, which may cause unnecessary failures or reduce the overall lifespan
  • Limited effectiveness in identifying certain types of defects or failure mechanisms
  • Difficulty in determining the optimal burn-in conditions and duration for a given product

Burn-in Test and the Bathtub Curve: The burn-in test is closely related to the concept of the bathtub curve, which represents the failure rate of a device over its lifetime. The bathtub curve consists of three regions: infant mortality, useful life, and wear-out. The burn-in test aims to identify and eliminate failures in the infant mortality region, where the failure rate is typically high due to latent defects and manufacturing issues. By removing the devices that fail during the burn-in test, the overall failure rate of the shipped products is reduced, resulting in a more reliable product.

Burn-in Test in the VLSI Design Flow: Burn-in testing is typically performed after the devices have been packaged and before they are shipped to customers. It is an important step in the manufacturing and quality assurance process, helping to ensure that the devices meet the required reliability standards. The results of the burn-in test can also provide valuable feedback to the design and manufacturing teams, enabling them to identify and correct any issues that may impact the reliability of the products.

Burn-in testing is a widely used technique in the electronics industry to improve the reliability of products, including VLSI circuits. By subjecting the devices to accelerated stress conditions and identifying early-life failures, burn-in testing helps to ensure that the devices shipped to customers have a lower failure rate and improved reliability.