HALT and HASS Accelerated Laboratory Testing
HALT and HASS testing help manufacturers uncover product weaknesses before they become costly field failures. Applus+ Keystone supports accelerated reliability programs for electronic, electromechanical, automotive, aerospace, defense, medical, and industrial products.
- A HALT test is usually performed during product development to reveal design margins and failure modes.
- A HASS test is generally used after design improvements are released to production to screen for manufacturing defects and process variation.
Our engineers develop test plans, apply controlled stresses, monitor performance, document failures, and provide information your team can use to improve reliability. Ready to get started? We are! Request a quote and see why manufacturers trust us in helping them get their product to market.
What Is HALT Testing?
HALT stands for Highly Accelerated Life Testing. It is a discovery-based method that applies progressively increasing stresses while a product operates under monitoring. The purpose of HALT testing is not simply to pass or fail a unit. It is to find weak points, determine why failures occur, and identify opportunities to make the design more robust.
Manufacturers often ask what is HALT testing when a product is failing qualification or producing intermittent field problems. HALT accelerated life testing is most useful while engineers can still change components, layouts, materials, cooling paths, software controls, or assembly methods.
How Does a HALT Test Work?
A typical HALT test begins with a review of the product, intended environment, known risks, monitoring requirements, and previous failure data. The unit is installed in a chamber and connected to power, communications, loads, sensors, and functional monitoring equipment. Stress is increased in controlled steps while engineers observe performance.
The HALT testing process includes cold and hot step stress, rapid thermal transitions, vibration step stress, combined temperature and vibration, power cycling, voltage margining, or other product-specific stresses.
What Is HASS Testing?
HASS stands for Highly Accelerated Stress Screening. It is a production screening method used to identify latent manufacturing defects, workmanship issues, component variation, and process changes before products reach customers.
Unlike HALT, HASS testing is performed on production or pilot-production units using stress levels selected from knowledge gained during HALT. A HASS test may combine rapid temperature changes, multi-axis vibration, electrical operation, and continuous functional monitoring. The screen must expose defective units without damaging properly manufactured products.
Manufacturers commonly perform a proof-of-screen evaluation before broad implementation. This confirms that the highly accelerated stress screening profile can detect relevant defects without harming acceptable units. Screen limits, dwell times, transition rates, vibration levels, fixtures, instrumentation, and acceptance criteria should be defined for the product.
HALT vs HASS: What Is the Difference?
The main difference in HALT vs HASS is where each method fits in the product lifecycle.
| Comparison | Highly Accelerated Life Testing (HALT) | Highly Accelerated Stress Screening (HASS) |
| Product Lifecycle Stage | Product development and design validation | Pilot production and ongoing manufacturing |
| Primary Purpose | Reveal design weaknesses, identify failure mechanisms, and evaluate operating margins. | Detect manufacturing defects, workmanship problems, and production inconsistencies. |
| Testing Approach | Progressively increases environmental and operational stresses beyond normal use conditions. | Applies a controlled and repeatable stress profile developed from HALT findings. |
| Typical Issues Identified | Component weaknesses, insufficient thermal margins, vibration sensitivity, connection failures, and design limitations. | Assembly defects, supplier variation, poor workmanship, loose connections, soldering issues, and process changes. |
| Desired Outcome | Improve the design before qualification testing or product release. | Prevent defective production units from reaching customers. |
| Pass or Fail? | Primarily a discovery process rather than a traditional pass-or-fail test. | Production units are screened against established functional and acceptance criteria. |
What Equipment Is Used for HALT HASS Testing?
Applus+ Keystone uses a Qualmark Typhoon 3.0 accelerated stress system to conduct HALT and HASS testing. This system is designed to combine rapid thermal transitions with six-degree-of-freedom repetitive shock vibration.
The chamber provides an operating temperature range of approximately -100°C to +200°C. Additionally, it can achieve thermal transition rates of up to 70°C per minute across typical HALT ranges. Its pneumatic actuators generate broadband, omni-axial repetitive shock energy across a wide frequency spectrum. This allows test articles to be stressed simultaneously in multiple directions.
Benefits of Accelerated Testing
This combined environment enables engineers to identify operational limits, destruct limits, resonant responses, intermittent electrical faults, solder-joint weaknesses, connector failures and other latent design or manufacturing defects that may not appear during conventional qualification testing.
A highly accelerated stress test is especially useful when traditional testing has not reproduced an intermittent field failure. Increasing stress in a controlled environment while monitoring the product may trigger the failure more consistently and produce better diagnostic evidence.
While many environmental tests can be considered forms of accelerated aging, HALT and HASS are specifically designed to apply much more aggressive stress levels. These methods use rapid temperature transitions, repetitive shock vibration, and combined environmental stresses to expose weaknesses in a much shorter period of time.
Industries That Use HALT and HASS
Aerospace and Defense Electronics
Qualmark HALT and HASS testing is well suited for aerospace and defense electronics that must remain dependable under demanding operating conditions. Units exposed to rapid temperature changes, repetitive shock vibration and combined stresses include:
- Avionics
- Communication systems
- Navigation equipment
- Power supplies
- Sensors and mission-critical control
Automotive and Electric Vehicle Components
Automotive electronics are frequently exposed to temperature extremes, road vibration and repeated mechanical stress throughout their service life. Qualmark HALT and HASS testing can be applied to:
- Electronic control units
- Battery-management systems
- Sensors
- Charging equipment
- Infotainment systems
- Lighting controls
- Other vehicle electronics
Consumer Electronics and Telecommunications
Consumer electronics and telecommunications equipment can benefit from HALT and HASS testing because even small design or manufacturing weaknesses may lead to early field failures. Products evaluated under rapid thermal transitions and six-degree-of-freedom repetitive shock include:
- Routers
- Network switches
- Communication modules
- Power adapters
- Smart-home devices
- Computers
- Electronic assemblies
Medical Devices and Industrial Equipment
Electronic medical devices and industrial systems often need to operate reliably for extended periods with limited opportunities for repair or replacement. Qualmark HALT and HASS testing can be applied to:
- Diagnostic equipment
- Monitoring devices
- Laboratory instruments
- Industrial controls
- Automation systems
- Power-conversion equipment
- Other electronic assemblies
HALT HASS Standards and Test Planning
Halt Hass testing standards vary from industry standards to customer specified laboratory conditions. Our team of qualified engineers assist manufacturers with a tailored test plan for intended environments and failure mechanisms. Testing standards include:
IEC 62506: Methods for Product Accelerated Testing – This standard establishes accelerated test techniques such as accelerated temperature, vibration and combined stresses.
IEC 61163-1 & IEC 61163-2: Reliability Stress Screening – The IEC spec describes methods to apply and optimize reliability stress screening processes. Specifically, for lots of repairable hardware assemblies, in cases where the assemblies have an unacceptably low reliability in the early failure period.
IEC 62429: Reliability growth – Testing for IEC 62429 includes early failures in unique complex systems. This International Standard evaluates reliability growth during final testing or acceptance testing of unique complex systems.
Mil-HDBK-2164A: Environmental Stress Screening (ESS) For Electronic Equipment – This standard evaluates the ESS process utilized for effectively disclosing manufacturing defects in electronic equipment caused by poor workmanship and faulty or marginal parts.
MIL-HDBK-344: Environmental Stress Screening (ESS) of Electronic Equipment – This handbook evaluates the cost effectiveness of ESS programs for electronic equipment.
MIL-STD-781 Task 401: Environmental Stress Screening (ESS) – This task offers information on ESS during full-scale development and production for overall reliability planning. Unless otherwise specified, random vibration is applied for a minimum of 10 minutes. Additionally, temperature cycling is performed at a rate of change less than 5 Celsius per minute.
MIL-STD-785 Task 301: Environmental Stress Screening (ESS) – Testing for this standard evaluates parts, workmanship defects, and other non-conformance anomalies.
IPC-9592C: Performance Parameters for Power Conversion Devices – The IPC standard applies primarily to AC/DC and DC/DC power supplies, converters, modules, and related circuit-board assemblies.
Custom Test Plans – While established standards provide a strong starting point, they may not always align with a manufacturer’s specific product requirements or validation strategy. Applus+ Keystone works with engineering teams to develop and execute custom HALT and HASS test plans tailored to the product, intended application, and objectives. Request a quote or contact our team to get the process started.
Why Choose Applus+ Keystone?
Applus+ Keystone supports manufacturers with environmental, vibration, temperature, shock, combined-environment, and product reliability testing.
Our team reviews the product and objective, defines functional monitoring, develops a customized procedure, and documents stress levels and observations. When failures occur, we provide information your engineers can use to investigate root cause and improve the product.
Whether you need a one-time HALT test, ongoing HASS testing, combined temperature and vibration, or a broader reliability program, contact Applus+ Keystone to discuss your product, development stage, known concerns, sample availability, and schedule.
Frequently Asked Questions
Is HALT the Same as Accelerated Life Testing?
HALT is a form of accelerated reliability testing, but it is usually a qualitative discovery process rather than a direct life-expectancy calculation. Traditional accelerated life testing may use models and failure data to estimate life under normal conditions.
Does a Product Pass or Fail HALT Testing?
HALT is generally conducted to find weaknesses and limits, not to earn a simple pass. A failure that can be understood and corrected before launch may be the most valuable outcome.
When Should HASS Testing Begin?
HASS should begin after HALT findings have been reviewed, corrective actions have been implemented, and the proposed screen has been validated.
Can HALT Replace Qualification Testing?
No. HALT does not replace required compliance or qualification testing. It can improve design robustness before qualification and reduce late-stage failures.
How Do I Request HALT Testing Services?
Provide a product description, dimensions and weight, power requirements, operating modes, intended environment, known failure concerns, available samples, and desired schedule. Applus+ Keystone can use this information to develop a customized HALT and HASS testing plan.