HALT & HASS Technical Paper – COTS Journal September 2005 :: Ralph Poplawsky, Chief Technology Officer, QualMark Corporation.

A lack of standards for the correct implementation of the stress test techniques known as HALT and HASS has resulted in widespread confusion. When implemented correctly, HALT and HASS provide a fast, cost-effective path to greater product reliability and customer satisfaction, as well as reduced warranty costs.

Introduction

Since they were first introduced in the early 1980s, Highly Accelerated Life Testing (HALT) and Highly Accelerated Stress Screening (HASS) have been successfully adopted for a host of high-performance applications, such as mission-critical avionics equipment.

With their promise of quickly providing valuable information about the reliability of a new or modified design, and the ability to monitor production and prevent  component variations from causing latent field reliability issues, HALT and HASS techniques are ideal for designing and manufacturing with commercial-grade  components.

Both test methods use direct inject, high flow rate liquid nitrogen cooling, tens of kilowatts of heating and powerful, multi-axis broad-spectrum vibration. Although these aggressive test methods are very different from standard life testing, design verification testing (DVT) and endof-production testing, there are no published industry standards that define these powerful test methods.

Since they deploy extreme stresses designed to rapidly precipitate flaws and force them to failure, misapplications or misinterpretations of these tests can easily result in damaged products, wasted money and frustrated engineers.