What is HALT/HASS?
February 1st, 2018
Don't miss our HALT Planning & Testing webinar on February 7th, hosted by Steve Laya, Elite’s Reliability and HALT / HASS Expert.
What is HALT/HASS?
Highly Accelerated Life Testing (HALT) is a process that utilizes a stepped stress approach in exposing your product to diverse accelerated stresses to discover the physical limitations of a design. Manufacturers can discover their products' failure modes and determine their failure mechanisms.
Highly Accelerated Stress Screening (HASS) is a production quality assessment to quickly and efficiently identify any weaknesses that the product may have inadvertently developed during the manufacturing stage.
Both are "Test, Analyze, Verify, and Fix" approaches - with Root Cause Analysis along the way!
Why should you perform HALT/HASS?
HALT finds weaknesses and flaws early in the design phase by testing to failure, while HASS catches manufacturing defects on production parts prior to installation without reducing the part's life. HALT also provides valuable data for reliability metrics at the component level. The test results benefit customers, protect the manufacturer's reputation, and prevent costly re-design later in the product development cycle.
What is unique about a HALT/HASS test chamber?
Unlike other environmental simlaution chambers, HALT/HASS chambers offer fast temperature ramp rates (up to 60C per minute) and combine thermal, vibration, and shock simulation in a single apparatus.
Vibration levels up to 50 Grms can be applied simultaneously in three linear axes (X, Y, and Z) and three rotational axes (pitch, roll, yaw).
How do you specify a HALT/HASS test?
HALT/HASS profiles are composed of several segments defined by the product's intended end-use environment:
- Cold Step Stress and Hot Step Stress: Incrementally decreasing or increasing the temperature to identify the product limitations. Select start and end points based on the end-use environment for the product and physical limitations of the components.
- Vibration Step Stress: Incrementally increasing the vibration levels while pausing on the way up to see how your product responds. Begin at a set Grms level, dwell for a specified duration, then increase to a higher amplitude and repeat the cycle to initiate failures.
- Rapid Thermal Transitions (or Thermal Shock): Subjecting your product to pre-defined maximum and minimum temperatures and rapidly cycling between them.
- Combined Environment: Simulating real world conditions where your product will be exposed to multiple random environments simultaneously.
Here are some common HALT/HASS acronyms used to specify test profiles:
- "Grms" - Vibrational G's in the root mean square, where "G" is acceleration due to gravity.
- "PSD" - Power Spectral Density - In a random vibration spectrum, it is the measurement of the amplitude and frequency.
- "LOL" and "LDL" - In the cold temp step stress stage, they are the "Lower Operating Limit" and "Lower Destructive Limit"
- "UOL" and "UDL" - The "Upper Operating Limit" and "Upper Destruct Limit " occur in the hot temp step stress stage.
Why choose Elite for HALT/HASS?
Our team of experts can support your test needs from planning stages, to testing, and failure analysis.
Elite's in-house machine shop allows us to design and fabricate any custom fixture or automation solutions to meet your specific product requirements.