Printed Circuit Boards (PCBs) are the foundation of every electrical and electronic device. The performance of any device depends on the reliability of its PCB. As companies strive to deliver more robust products with shorter development cycles and reduced costs, product testing becomes critical throughout the Product Development Lifecycle (PDLC). This blog will focus on two essential testing methods: HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening).

Why HALT and HASS Testing Matter in Product Development

HALT and HASS testing give manufacturers a competitive edge by allowing them to identify and resolve design and production issues early. HALT testing occurs during product design, pushing products to their limits to identify weaknesses, while HASS testing is used in mass production to screen out faulty units. These tests ensure reliability, reduce life cycle costs, and improve overall product quality.

What is HALT and HASS Testing?

HALT (Highly Accelerated Life Testing): HALT is a stress testing process that helps validate a product’s reliability during the engineering development phase. By exposing the product to extreme stresses like temperature and vibration, HALT helps uncover design weaknesses and operational limits.

HASS (Highly Accelerated Stress Screening): HASS is used during production to screen for weaknesses in mass-produced products. It ensures that faulty units are identified before they reach the consumer, preventing failures in the field.

Key Differences Between HALT and HASS

HALT: Used during the design phase to test prototypes (MVPs), HALT helps identify design flaws before mass production begins.
HASS: Performed during production, HASS identifies manufacturing flaws in a short time frame, ensuring only robust products reach the market.
How HALT Testing Strengthens Product Design

HALT testing goes beyond traditional testing methods by applying incremental stresses that exceed typical operating conditions. By continuously pushing a product until it fails, engineers can learn valuable insights about design and material limitations. HALT testing is not a pass/fail test; rather, it requires root cause analysis (RCA) and corrective actions to improve the product's durability and reliability before market launch.

The Complete HALT Testing Process

Low/Cold Temperature Step Stress: Gradually reduce the temperature until the product starts malfunctioning, identifying the Lower Operating Limit (LOL).
High/Hot Temperature Step Stress: Gradually increase the temperature to find the Upper Operating Limit (UOL).
Rapid Thermal Cycling: Apply rapid thermal transitions to uncover material weaknesses.
Vibration Step Stress: Secure the product to a vibration table and incrementally increase vibration levels to uncover defects.
Combined Environment Stress: Apply thermal and vibration stresses together to detect additional failures.
How HALT and HASS Test Chambers Differ from Other Testing Chambers

HALT and HASS chambers offer unique advantages, combining rapid temperature ramp rates with vibration and shock simulation. These chambers can apply vibrations in three linear and three rotational axes simultaneously, allowing for comprehensive testing of product durability under extreme conditions.

Benefits of HALT Testing for Product Development

Lowers product development costs by identifying flaws early.
Reduces time-to-market by uncovering design issues before mass production.
Enhances product reliability, leading to fewer warranty claims and higher customer satisfaction.
Improves product life expectancy predictions.
Ensures robust design by continuously improving through iterative testing.
Why HASS Testing is Crucial for Production Quality

HASS testing helps ensure that products coming off the production line meet the same reliability standards as those tested during HALT. By applying stress levels lower than HALT, HASS exposes latent failures without reducing the product’s life. The testing profile for HASS is typically determined during the Proof of Screening (POS) process, which ensures the screening process is effective but does not damage functional units.

Benefits of HASS Testing in Production

Identifies manufacturing defects, preventing faulty units from reaching the market.
Detects early failures in components, ensuring the reliability of assembled PCBs.
Reduces warranty and RMA costs by weeding out weak units before customer use.
Verifies the mechanical and electrical integrity of the product.
Uncovers issues related to changes in hardware, firmware, or production processes.
Real-World Example: HALT and HASS Testing in IoT Gateway Development

At ACL Digital, our hardware engineering team successfully used HALT testing to simulate extreme temperature and vibration conditions for an IoT gateway used in telematics and fleet management. By applying the SAE-J1455 automotive standard, the team derived HALT test specifications and implemented HASS screening in mass production. As a result, the product offered enhanced reliability with a three-year warranty.

Conclusion: Enhancing Product Reliability with HALT and HASS Testing

HALT and HASS testing play critical roles in ensuring that products are not only robust but also reliable throughout their lifecycle. By identifying design and manufacturing weaknesses early on, these tests help companies bring better products to market faster, with reduced development costs and fewer warranty claims.

For more information on ACL Digital’s hardware engineering services and our success stories, visit our website.