HALT Testing / HASS Testing

Highly Accelerated Life Testing (HALT) is a specialized reliability test during which the product is exposed to extreme environmental conditions until it ultimately fails. Highly Accelerated Stress Testing (HASS) can be used as a quality assurance test for components and small devices. The two tests are essential tools used in making products and components robust.


HALT Testing / HASS Testing

During a routine five-step HALT test, the unit under test is subjected to a combination of vibration and rapid transitions to extremely high and low temperatures. The testing exposes the product to conditions far beyond what would be encountered in the field environment and is commonly used during product development. Highly Accelerated Stress Screening (HASS) is a quality assurance or screening test used for components or sub-assemblies. HASS testing continues until the point of failure is reached; it is often preceded by HALT. The same chamber can be used for both HALT and HASS testing.

What is the relationship between HALT and HASS testing?

Both HALT and HASS use a combination of vibration and rapid transitions to extreme hot and cold temperatures to create a high-stress environment.

HASS, a component-level test that can stress the unit under test to a predetermined level, can be used as a screening tool to identify high or low-quality components.

HALT, often a precursor to HASS testing, is used in the development process to characterize product durability or robustness. The testing uses a series of progressively more difficult combinations of rapid temperature extremes and vibration to stress the unit under test to the point of failure.

Together, these tests can identify potential problems in the product’s design, materials, or manufacturing process. Then, after testing completes, designers and manufacturers can use the high-quality test data to improve the product and possibly avoid costly mistakes.

What is the purpose of Highly Accelerated Life Testing and Highly Accelerated Stress Screening?

Although HALT and HASS testing are subjected to similar test inputs, their primary objectives are different. Put simply, the basic goals of HASS and HALT testing are the following:

  • HALT: Identify failure points to then improve upon, thereby increasing a product’s robustness and longevity.
  • HASS: Identify either high or low-quality components enabling a higher quality product.

To gain a better understanding of the function of these tests and how they may be applied to your product, let’s dive into more detail.

HALT testing, also known as Highly Accelerated Life Testing, is a reliability test performed during a product’s early development or design stage. The test is engineered to precipitate failures by exposing the test sample to combined temperature and vibration stressors. During a HALT test, a product will endure rapidly increasing mechanical and thermal stresses until failure occurs. With HALT testing, developers can glean essential clues to find the source of defects, create corrective actions, and ultimately produce high-quality, reliable products.

  • HALT tests generally include a series of dwells at high and low temperatures, vibration, rapid cycling between high and low temperatures, followed by combined test environments.

After HALT testing concludes, the resulting test data can be used by developers to establish the product’s operational and failure limits and improve product reliability. When screening components is the objective, HALT test data is often used to design the HASS test parameters.

HASS testing, also called Highly Accelerated Stress Screening, is a production screen that identifies components meeting specific criteria. HALT results are used to establish the test limits for HASS; therefore, HASS typically follows HALT. Test units for HASS testing typically come from batches from the production line. This screening process can help determine if a specific lot may have potential issues. The HASS testing process utilizes similar combined environments as HALT. Additionally, HASS test data may help establish the impact of alternative components on a product’s design and durability.

What are the differences between HASS and HALT testing?

Although HASS and HALT testing procedures use the same equipment and stressors, here are key differences between the two tests.

Objective Identify product failure points Identify components meeting predetermined pass/fall criteria
Failure Limit Test unit stressed to point of destruction Test unit subjected to test limits aided with HALT data
Test Sequence Precursor for HASS testing Typically follows HALT
Test Result Usage Often used in the product development process Often used as a quality screening tool for components
Purpose Helps teams design high-quality products
Determine the failure points of products
Helps teams produce high-quality products
Screen out components not meeting pass/fail criteria

Frequently Asked Questions

Get answers to our most frequently asked questions.

What are the typical stresses used in HALT and HASS testing?

HALT/HASS test samples will endure both temperature and vibration stressors during testing.

Westpak’s test chamber capabilities are as follows:

  • Up to 60°C / minute average transition rate
  • Six degrees of freedom vibration
  • 5-60 Grms vibration level
  • Upper temperature extremes of +200°C
  • Lower temperature extremes of –100°C
  • Multiple ports for external device monitoring and operation
  • 30” x 30” vibration table

What are some of the benefits associated with HALT and HASS testing?

HALT and HASS testing offer a variety of benefits to product manufacturers, including:

  • Fast results— stress levels that would take months to simulate can be achieved in hours
  • A more robust product which results in fewer returns due to manufacturing or packaging flaws
  • Fewer problems in the field and fewer upset customers
  • With use of HASS you can make sure that there are no effects to the overall product robustness due to:
    • Manufacturing changes
    • Component changes
    • Material changes
    • Design modifications
  • HASS/HALT testing are quick and cost-effective additions to your reliability program during the early stages of the product development process


Westpak is certified by A2LA as an ISO 17025 accredited laboratory.

Westpak testing labs are ISTA certified to perform a variety of tests.


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