HALT and HASS require specialized equipment and specialized training to achieve optimum product ruggedness and full financial benefits of accelerated testing.
Understanding that HALT and HASS are not intended to be a Design Verification Test (DVT) is critical to successful implementation of an accelerated reliability program. The goals of HALT are entirely different. The key difference? Unlike DVT, HALT is not a pass/fail test. There are no pre-established limits for HALT.
|HALT versus DVT
Different Purpose; Different Results
|Verifies that product meets specification||Stresses product beyond specification|
|Verifies that product will function in its intended environment||Stresses product until weak points fail|
|Is successful when product shows no failures||Determines functional and destruct limits|
|Is successful when failure modes are found and eliminated|
HALT and HASS for a different purpose and for different results - so that manufacturers can accelerate time to market with a more reliable and profitable product.
Successful HALT requires input from multiple disciplines; design engineering, test engineering, reliability engineering, manufacturing engineering and HALT system technicians. This HALT team will define test specifications, functional test requirements, methods of fixturing the product to the table, product components and/or locations to monitor with thermocouples, accelerometer placement, and define what constitutes a failure. ESPEC Qualmark's Professional services can assist with HALT/HASS program development and management.
ESPEC Qualmark HALT Chamber is specially engineered to produce the simultaneous extreme thermal and vibration energy necessary for accelerated reliability testing. Fixtures are required to properly secure the test product to the HALT chamber's table. Since product thermal and vibration response data, as well as functional performance, is measured during the HALT process, thermocouples and accelerometers or other means of measurement are required. Data acquisition can be collected by the system's resident monitoring system or by ancillary lab monitoring systems. Accommodations for thermal (LN2) injection must be also considered.
The HALT system operator must be fully trained and understand the goals of HALT, what stresses to apply when, in what combination, how to monitor the product under test, and how to detect failures. We offer numerous educational opportunities for becoming certified in accelerated stress testing.
The HALT process continues after completion of discovering failure modes. The next process is determining why the failure(s) occurred and deciding what should be done about them. Temporary fixes are made and the HALT process is continued until the fundamental limits of the product have been reached. By feeding failure analysis back into the design team, flaws can be eliminated, margins can be increased, and a more robust product developed.
HASS is a Highly Accelerated Stress Screen that is performed during manufacturing to ensure process integrity and to minimize marginal product getting released to the field. Most often, companies will implement HASS as a separate, second phase of accelerated reliability test integration.
ESPEC partners with approved Accelerated Reliability Test Centers® across the globe that have both the equipment and technical expertise necessary to properly conduct HALT and HASS to improve your product. These centers perform a complete HALT on your product in a mere three to five days and provide a complete report for your design team.