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It is easy to understand why the term HALT (Highly Accelerated Life Test) is so tightly couple to the equipment called “HALT chambers” systems. Many do not think they can do HALT processes without a “HALT Chamber”. Many know that Dr. Gregg Hobbs, who coined the term HALT and also HASS (Highly Accelerated Stress Screens), spent much of his life promoting the techniques and was also the founder of two “HALT/HASS” environmental chamber companies. [Read more…]
Many reliability engineers have discovered HALT will quickly find the weaknesses and reliability risks in electronic and electromechanical systems from the capability of thermal cycling and vibration to create rapid mechanical fatigue in electronic assemblies. Assemblies that have latent defects such as cold solder or cracked solder joints, loose connectors or mechanical fasteners, or component package defects can be brought to a detectable, or patent, condition by which we can observe and potentially improve the robustness of an electronics system.
Traditional electronics reliability engineering began during the period of infancy in solid state electronic hardware. The first comprehensive guide to Failure Prediction Methodology (FPM) premiered in 1956 with the publication of the RCA release TR-1100: “Reliability Stress Analysis for Electronic Equipment” presented models for computing rates of component failures. “RADC Reliability Notebook” emerged later in 1959, followed by the publication of a military handbook know as that addressed reliability prediction known as Military Handbook for [Read more…]
In all aspects of engineering we only make improvements and innovation in technology by building on previous knowledge. Yet in the field of reliability engineering (and in particular electronics assemblies and systems), sharing the knowledge about field failures of electronics hardware and the true root causes is extremely limited. Without the ability to share data and teach what we know about the real causes of “un-reliability” in the field, it is more easily understood why the belief in the ability able to model and predict the future of electronics life and MTBF continue to dominate the field of electronics reliability
Kirk and Fred discuss steps that should be followed when trying to find the location and cause of failures in electronics.
They use examples of from their own experiences with recent failures of appliances and personal computers and how using a systematic approach to investigating failures is the best way to discover the causes of failures.
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Kirk and Fred discuss how to know when a failure occurs during a stress test to find operational and destruct limits.
In some cases, the failure and component causing the failure are very obvious when “the smoke comes out”.
In other cases, the product being tested has a performance degradation under increased stress that can be used as discriminators for ensuring reliability and quality during product development and manufacturing.
They also discuss how some fundamental technology limitations of common operational monitors, such as a display LCD, does not have to limit the stress to the more typically more capable circuit board assembly.
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When we go to an automobile race such as the Indianapolis 500, watching those cars circle the track can get fairly boring. What is secretly unspoken is that everyone observing the race is watching for a race car to find and sometimes exceed a limit, finding a discontinuity. The limit could be how fast he enters a curve before the acceleration forces exceed the tires coefficient of friction, or how close to the racetrack wall, he can be before he contacts it and spins out of control. Using the race analogy, [Read more…]
Most reliability engineers are familiar with the life cycle bathtub curve, the shape of the hazard rate or risks of failure of a electronic product over time. A typical electronic’s life cycle bathtub curve is shown in figure 1. [Read more…]
Historically Reliability Engineering of Electronics has been dominated by the belief that 1) The life or percentage of complex hardware failures that occurs over time can be estimated, predicted, or modeled and 2) Reliability of electronic systems can be calculated or estimated through statistical and probabilistic methods to improve hardware reliability. The amazing thing about this is that during the many decades that reliabilityengineers have been taught this and believe that this is true, there is little if any empirical field data from the vast majority of verified failures that shows any correlation with calculated predictions of failure rates.
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Kirk and Fred discuss a few of the essential steps as you turn on the HALT stresses.
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Kirk and Fred discuss a few of the essential steps before you turn on the HALT stresses.
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Kirk and Fred discuss the history and evolution of environmental stress testing practices leading to HALT.
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Kirk and Fred discuss how to approach developing a HALT for a discrete component that a vendor claims is more reliable.
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Kirk and Fred discuss the notion of designing for HALT and why that isn’t a good idea.
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Kirk and Fred discuss what is meant by HALT or highly accelerated life testing.
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