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Understanding the Highly Accelerated Life Test (HALT): A Comprehensive Guide

Learn more about our various reliability testing services including our HALT Testing Services. The article below explains the process of HALT and why it is important.

halt testing service

Highly accelerated life testing (HALT) is a method used to test solid-state electronics and determine failure modes, operational limits, and destruct limits and design weaknesses over rapid test time. This test method differs significantly from reliability tests. HALT testing does not determine a statistical reliability or determine an estimated life. Reliability tests such as accelerated reliability testing or accelerated life testing are used to calculate reliability performance metrics such as mean time between failures.

Key industries that commonly utilize HALT testing include:

  1. Electronics and Semiconductor: HALT testing is extensively used in the electronics industry to test components, circuit boards, and consumer electronics devices. This includes smartphones, laptops, tablets, and other personal electronic devices to ensure they can withstand a range of environmental stresses.
  2. Automotive: In the automotive industry, HALT is used to test the reliability of various electronic components, sensors, and control units in vehicles. This ensures that these components can endure the harsh conditions they may encounter during the vehicle’s lifespan.
  3. Aerospace and Defense: Given the extreme conditions that aerospace and defense equipment must withstand, HALT testing is crucial for components such as avionics, control systems, and various onboard electronics. It helps in ensuring the highest level of reliability and safety.
  4. Medical Devices: HALT testing is used to ensure the reliability and durability of medical devices and equipment. This includes diagnostic machines, life-support systems, and other critical medical technologies that must perform flawlessly in critical conditions.
  5. Telecommunications: The telecommunications industry uses HALT to test the durability and reliability of networking equipment, including servers, routers, switches, and other infrastructure hardware. This helps in ensuring continuous and reliable operation under varying environmental conditions.

Halt highly accelerated life test

The halt process is a simple basic principle – if you wish to fatigue a component, semiconductor IC, subassembly or finished product you can stress it with lower levels of stress for a lot of cycles, or use a higher level of stress for a fewer number of cycles.

In a HALT test, every stimulus of potential value is used to find the weak links in the design and fabrication processes of a product during the design phase.  This screening process reduces field failures and helps improve the fabrication processes.

A HALT typically takes two or three days. Also, a HALT will identify several failure modes providing significant information for the design engineers to improve the product. Typical reliability tests will provide one or two failure modes, if the product fails at all.

Traditional reliability tests such as accelerated reliability testing (ART) and accelerated life testing (ALT) use accelerated stress conditions uniformly and consistently to expose failures and to develop acceleration factors to equate the stresses applied in a test to reliability or to life in the actual customer use environment.

Field failures before product launch

Rather than applying low stress levels over long durations, HALT testing applies high stress levels for short durations well beyond the expected field environment. This testing is a great way to prevent future warranty claims because it can identify weaknesses and is great in the aerospace industry.

Halt testing is often used during the design phase of a system by applying increased stress to a product in incremental steps increasing variables until anomalies occur and fixing faults, if discovered, to improve the design. This process continues beyond the limits of normal shipping, storage and operational conditions normally encountered in the fields until the destruction limits of the material in the product are reached.

With the halt process, acceleration factors are difficult if not impossible to determine, and test time cannot be correlated to customer use time.

To consider the meaning of HALT from another angle, let’s analyze what HALT cannot do:

  • HALT is not intended to find and fix all failures. The failures that affect product reliability should be resolved and an awareness developed of failure modes at stress conditions well beyond the design specification limits.
  • HALT is not a qualification test.
  • HALT has no pass/fail criteria

HALT & MTBF

HALT is a qualitative test—the objective is to expose design weaknesses. The HALT will not show a service life or a mean time between failures (MTBF). Other reliability methods may be a better fit to predict an MTBF or service life. Once a weakness is exposed by the test design or engineering solutions can be found to remedy the flaw.

What is Highly Accelerated Life Testing (HALT)?

Highly accelerated life testing (HALT) is a method used to test solid-state electronics and determine failure modes, operational limits, and destruct limits and design weaknesses over rapid test time. This test method differs significantly from reliability tests. HALT testing does not determine a statistical reliability or determine an estimated life. Reliability tests such as accelerated reliability testing or accelerated life testing are used to calculate reliability performance metrics such as mean time between failures.

Definition and Principle of HALT

  • HALT is an intensive testing methodology that aims to uncover design defects and weaknesses in electronic and electromechanical assemblies. Also called accelerated life tests, it can find issues in the operating and destruct limits.
  • It delivers temperature stresses, rapid thermal cycling, and random, tri-axial vibrations/shocks to reveal design weaknesses and product problems.
  • The key objectives of HALT testing are identifying weak points, optimizing reliability, and shortening time-to-market.

Halt Tests Process

Preparatory Stage

  • Before conducting a HALT test, meticulous preparation is essential.
  • The process begins with a comprehensive analysis of the product’s intended use and performance requirements.
  • Engineers identify critical functions and potential weak points in the design.

Stress Testing Stage

  • The stress testing stage is the core of HALT.
  • Stresses are systematically applied to the product in an ordered sequence, aiming to push it beyond its operational limits and uncover potential failures.
  • The sequence includes thermal step stress, cold step stress, hot step stress, rapid thermal transition cycling, vibration step stress, and combined environment.

Identifying Product Limitations

  • At each level of applied stress, functional testing is performed on the product sample to evaluate its operation.
  • When a failure occurs, the failure mode and stress level is recorded, the failure location is isolated, and the root cause of the failure is determined.

HALT Testing Methodology

Typical HALT Procedures

  • Environmental stresses are applied in HALT, including hot and cold temperatures, temperature cycles, random vibration, power margining, and power cycling.
  • The product under test is continuously monitored for failures, and the cause of stress-induced failures should be determined and repaired if possible.
  • The output of HALT gives information on the product’s reliability and weaknesses.

Test Chambers and Fixtures

  • A specialized environmental chamber is required for HALT, capable of applying pseudo-random vibration and temperatures from -100 to +200°C.
  • The chamber should be capable of rapid changes in temperature and applying random vibration energy from 2 to 10,000 Hz in 6 degrees of freedom.
  • Fixtures must transmit vibration to the item under test and allow for rapid temperature change to internal components.

Multiple Failure Modes

Real-time Monitoring and Data Collection

  • The equipment under test must be monitored to detect failures, typically using thermocouple sensors, vibration accelerometers, multimeters, and data loggers. These can test for vibration stresses under normal operating conditions.
  • Common causes of failures during HALT are poor product design, workmanship, and poor manufacturing.

Failure Analysis and Root Cause Identification

  • Failures during halt test are associated with the infant mortality region of the bathtub curve.
  • The root cause of each failure mode is identified, and corrective actions are taken to improve the product’s design and fabrication processes.

Applications of Highly Accelerated Life Testing

Military Application

  • Halt test is conducted before qualification testing to catch failures early and eliminate repetitive later-stage reviews.
  • By identifying weaknesses early, halt tests eliminate the need for later-stage reviews and improves product reliability.

Industries That Rely on HALT

  • HALT testing has emerged as a pivotal practice to ensure products across a host of industries are resilient, dependable, and capable of withstanding the rigors of their respective environments.
  • Industries that rely on HALT include aerospace, defense, automotive, and telecom.

Highly Accelerated Stress Screening (HASS)

What is HASS?

  • Highly accelerated stress screening (HASS) is a complementary testing method to highly accelerated life testing (HALT) that helps precipitate failures, in mass-produced products quickly.

Similarities and Differences Between HALT and HASS

  • Both HALT and HASS employ accelerated stress testing to expose weaknesses and defects in products.
  • The main distinction between HALT and HASS lies in the timing and purpose of the testing.
  • HALT is a design optimization process that seeks to push products to their limits and improve overall robustness.
  • HASS is a screening process that aims to quickly identify and remove defective units from the production batch.

The Impact of Highly Accelerated Life Testing on Product Development and Life Cycle

  • HALT testing stands as a transformative force, revolutionizing the way we ensure product reliability, performance, and longevity.
  • By incorporating HALT into the design process, companies can elevate the overall product life cycle.
  • HALT testing can lower product development costs and compress time to market by identifying weaknesses early.
  • It can also help to reduce the cost of solar power generation and increase its efficiency.