Test Type to Catch Supplier Defects

Highly Accelerated Stress Screening (HASS) and Highly Accelerated Stress Audit (HASA) are advanced testing methods used to identify potential defects in full assemblies, while burn-in testing is typically applied at the component level. These tests are designed to expose products to extreme conditions to precipitate failures, allowing for corrective actions before the products reach customers.

HASS (Highly Accelerated Stress Screening)

HASS is used after the product design has been finalized and the HALT (Highly Accelerated Life Test) has identified the product’s operational limits. It is a production screen designed to expose manufacturing defects that could lead to early life failures.

Steps in HASS:

1. Stress Application: Apply all stresses simultaneously, such as vibration and temperature cycling, to the product.
2. Stress Levels: Determine stress levels based on HALT limits, ensuring they are high enough to precipitate defects but not so high as to damage the product.
3. Additional Stresses: Include any product-specific stresses identified during HALT, such as power cycling or specific operational loads.
4. Precipitation Screen: Conduct tests beyond operating limits, near destruct limits, to precipitate latent defects.
5. Detection Screen: Evaluate the product near operating limits to confirm and explore precipitation screen failures, including both hard and soft failures.HASA (Highly Accelerated Stress Audit)HASA is a subset of HASS and is used to monitor the consistency of the manufacturing process over time. It is typically performed on a sample of units rather than the entire production.Steps in HASA:

1. Sampling Plan: Design a sampling plan that will quickly signal when process variations occur.
2. Stress Application: Apply HASS stress levels to the sampled units to reveal production-induced defects.
3. Process Monitoring: Use HASA to ensure that no new defects are introduced into the manufacturing process.
4. Ongoing Evaluation: HASA is a dynamic process that may require adjustments as the product and manufacturing process evolve.Burn-In Testing at Component LevelBurn-in testing is a reliability engineering method used to detect early failures in electronic components.Steps in Burn-In Testing:

1. Stress Application: Subject components to elevated temperatures and possibly elevated voltages to accelerate aging.
2. Continuous or Periodic Testing: Components may be under continuous test or simply tested at the end of the burn-in period.
3. Failure Analysis: Analyze failed components to determine the cause of failure and take corrective actions.SummaryHASS and HASA are used to ensure the reliability of full assemblies by exposing them to accelerated stress conditions to identify defects. Burn-in testing at the component level serves a similar purpose but focuses on individual components before they are assembled into the final product. These tests are crucial for improving product reliability, reducing warranty costs, and increasing customer satisfaction by catching defects early in the manufacturing process.