HALT vs. HASS Testing: From Design Limits to Production Screening

SANWOOD's HALT & HASS Chambers combine temperature and multi-axis vibration stresses for accelerated reliability testing. Selecting a configuration starts with the test objective, the assembly being tested and the conditions that must reach the mounted product.

HALT vs HASS: purpose, stresses and results

HALT applies temperature and vibration stresses, separately or together, to investigate weaknesses and identify operating and, where appropriate, destructive limits. The results guide failure analysis and design improvements. HASS uses a product-specific screening profile to help reveal manufacturing-related defects after the design and screen have been evaluated.

Neither HALT nor HASS, on its own, predicts service life or replaces a product qualification test against specified requirements.

Which approach fits your project?

For a new PCBA or electronic module, HALT can help locate functional weaknesses under increasing stress. Findings are useful when they lead to a technical explanation, corrective action and follow-up evaluation. The aim is to learn how the design behaves, rather than to pass a fixed screening profile.

For a design moving into production, HASS asks a different question: can a practical screen reveal relevant manufacturing defects without unacceptable damage to conforming units? A screen already in service may also require reassessment when a fixture, sample loading arrangement or monitored connection changes.

SANWOOD chamber features and what they mean for selection

The SANWOOD HALT/HASS Chamber combines a thermal enclosure with a pneumatic repetitive-shock vibration table. Three features are particularly relevant when matching the equipment to the test plan.

LN2 cooling and rapid thermal transitions. Liquid nitrogen (LN2) cooling supports rapid temperature changes. Required transitions should be discussed in relation to the installed sample and fixture load; chamber-air readings do not necessarily describe the temperature response of a PCB or module.

Six-degree-of-freedom vibration and fixture transmission. The multi-axis vibration table provides mechanical excitation, but mounting stiffness, attachment points and fixture layout influence how it reaches the assembly. A table-level vibration figure alone cannot establish the stress at every component location.

Combined temperature and vibration stress. Applying both stresses together can be useful when the investigation or screen calls for combined exposure. Functional connections and monitoring need to remain suitable for the intended sample arrangement.

From HALT findings to a validated HASS profile

HALT results can inform HASS development after relevant design weaknesses have been addressed. They do not establish a universal temperature setting, vibration percentage or cycle count for production screening.

A HASS profile must be developed and evaluated for the intended product and production setup. Proof of Screen considers whether the screen can detect the relevant defects while avoiding unacceptable effects on conforming units. Demonstrating that good units survive repeated screening is important, but does not by itself prove that the screen can detect the target defects.

Can one chamber support both HALT and HASS?

A suitably configured system may support both activities, although the HALT investigation and the HASS screen remain different processes. For PCB assembly and electronic-module testing, development work may prioritize accessible fixtures and flexible connections, while production screening may require greater loading capacity, efficient changeovers and a defined throughput.

For example, moving from a single-board development fixture to a multi-board production fixture can change thermal response, vibration transmission and monitoring access. A shared chamber needs to be assessed for both arrangements, rather than chosen on chamber specifications alone.

Before selecting equipment for both uses, confirm:

• The thermal and vibration requirements for each task, including where performance is measured.

• Sample and fixture dimensions, mass, mounting positions and handling access.

• Sample power, expected heat load, functional monitoring and external connections.

• Production loading, changeover time, scheduling and expected screening throughput.

• Site readiness for liquid nitrogen, compressed air and the installation requirements of the proposed configuration.

Discuss your requirements with SANWOOD

When discussing a HALT/HASS chamber with SANWOOD, provide the project stage, sample and fixture details, intended thermal and vibration conditions, and functional-monitoring needs. If one system is expected to serve both development and production, include both loading arrangements so the proposed configuration and external integration can be reviewed together.

For more information about SANWOOD HALT/HASS Chambers, contact info@sanwood.com to discuss your testing requirements and equipment configuration.