Exploring the differences between HALT and ALT, or Highly Accelerated Life Test and Accelerated Life Test. Plus when to use which when.
[Read more…]HALT or ALT
Articles tagged Highly Accelerated Life Testing (HALT)
An experiment to quickly discover weaknesses in an item’s design or assembly process by applying increasing steps of one or more stress vectors until failures occur.
Why HALT is not HALT
An excellent short white paper by Craig Hillman that is worth reading. It underscores why I claim HALT is the second worst 4 letter acronym in our profession.
[Read more…]No Evidence of Correlation: Field failures and Traditional Reliability Engineering
Historically, Reliability Engineering of Electronics has been dominated by the belief that 1) The life or percentage of complex hardware failures that occur over time can be estimated, predicted, or modeled, and 2) the 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 reliability
[Read more…]4 Different Types of Reliability Testing
Getting the Right Information from Your Reliability Testing
You cannot test in reliability any more than you can test in quality. Often reliability testing is done though, and knowing the range of testing approaches and their associated results will help you get the most information from each test conducted.
Let’s explore the types of testing that generate information useful as you develop a reliable product. There are 4 different types of reliability testing:
- Discovery
- Life
- Environmental
- Regulatory
Within each type there are many variations to the testing details and the specific results generated. Understanding the questions each type of testing has the capability to resolve is a good first step to implementing the right set of tests for your project. [Read more…]
4 Steps to Accomplish HALT
4 Not Always Easy Steps
Highly Accelerated Life Testing, HALT, is a method to discover the weaknesses in a design. Using a step stress approach of single and combined stresses, you can quickly expose the salient weaknesses in your design and/or assembly process.
The value of HALT is it’s quick and often finds problems not previously known. You will destroy one or more prototypes, yet the value of knowing specifically what needs improvement more than justifies the sacrifice of a few photos.
Conducting HALT may be part of your reliability plan. Keeping a few steps in mind will help make sure your HALT does provide value back to your development efforts. [Read more…]
Seminar: HALT Techniques and connecting to program objectives
This is the third session from the Annual Apex Ridge Reliability Seminar held in Boston.
In this session, I discuss the methodology of HALT and how to connect it with program tools and objectives.
The philosophy of HALT is often misunderstood simply due to its name and acronym, “Highly Accelerated Life Testing” (HALT).
It is not an accelerated life test, it’s really not even a test. HALT is a process of increasing stress on a design to induce failures for the purpose of learning about the design and improving its robustness.
It’s a discovery process. [Read more…]
You May Often be Exceeding Operating Specifications!
HALT (Highly Accelerated Life Test) requires exceeding specifications
One aspect of HALT, (a test to find weaknesses and reliability risks empirically), is the difficulty for many engineers that are new to the HALT- that it guarantees that the maximum or recommended operating environmental specifications for the system and components under test will be exceeded, and failures beyond spec are potentially relevant to field reliability. [Read more…]
Eliminating early life failures
MTBF for electronics life entitlement measurements is a meaningless term. It says nothing about the distribution of failures or the cause of failures and is only valid for a constant failure rate, which almost never occurs in the real world. It is a term that should be eliminated along with reliability predictions of electronics systems with no moving parts. [Read more…]
Why success with HALT begins long before doing HALT
Implementing a new reliability development paradigm in a company which is using traditional, standards-based testing can be a perilous journey.
It is especially true with introducing HALT (Highly Accelerated Life Test) in which strength against stress, and not quantifying electronics lifetimes is the new metric. Because of this significant change in test orientation, a critical factor for success begins with educating the company’s top [Read more…]
Why HALT is a methodology, not equipment
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…]
Why Parametric Variation Can Lead to Failures and HALT Can Help
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.
For Maximum Test Value, Take it to the Limit!
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…]
No Evidence of Correlation: Field failures and Traditional Reliability Engineering
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.
[Read more…]
Does HALT Lead to Product Over-Design?
Every once in a while I see a comment that by following the HALT methodology you will “over design” a product.
Many question at what point or operational limit do you quit increasing the stress-strength margins. Those who hold this view of HALT do not understand the essence of what was Gregg Hobbs’ principles and paradigm shift. [Read more…]
A Brief Introduction to HALT
Highly Accelerated Life Testing (HALT) is a technique to expose weaknesses or faults with a product.
HALT uses individual or combined stresses in a step stress approach to quickly apply sufficient stress to reveal defects.
HALT is not a specific chamber or fixed set of test conditions. It is an exploratory process to reveal weaknesses in a design.
The product development process naturally includes a check step, to determine if the expected functions of the product work as expected.
Some teams then add a measured amount of stress (temperature, vibration, dust, load, etc.) to the product to explore functionality at elevated stress levels. [Read more…]
