A technique for production screening that rapidly exposes process or production flaws in products. Its purpose is to expose a product to optimized production screens without affecting product reliability. Unlike HALT, HASS uses nondestructive stresses of extreme temperatures and temperature change rates with vibration.
HASS Testing (Highly Accelerated Stress Screening) is a proven test method developed to find Manufacturing/Production-process induced defects in electronics and electro-mechanical assemblies before those products are released to market. HASS is a powerful testing tool for improving product reliability, reducing warranty costs and increasing customer satisfaction.
After a product has undergone HALT Testing, HASS Testing can be deployed in the production process. Once the product is made robust (through the application of HALT), the next logical step is to monitor the production processes using a technique called Highly Accelerated Stress Screening (HASS). The goal of a HASS is to induce failure modes that can be inherent or introduced in the production process. HASS have been proven to be effective in screening failures that may have gone undetected in the burn-in testing process. A product that passes normal production tests but fails in a HASS would have probably failed early after product release increasing warranty costs.
HASS - Highly Accelerated Stress Screening: Is used to improve the robustness/reliability of a product through test-fail-fix process where the applied stresses may be beyond the specified operating limits (OL) determined by HALT. This is applied to 100% of the manufactured units.
There are 2 parts to HASS Testing:
1. HASS Development/Proof-of-screen (POS)
2. HASS Production Screen.
Since HASS levels are more aggressive than conventional screening tools, a POS procedure is used to establish the effectiveness in revealing production induced defects. A POS is vital to determine that the HASS stresses are capable of revealing production defects, but not so extreme as to remove significant life from the test item. Instituting HASS to screen the product is an excellent tool to maintain a high level of robustness and it will reduce the test time required to screen a product resulting in long term savings. Ongoing HASS screening assures that any weak components or manufacturing process degradations are quickly detected and corrected. HASS is not intended to be a rigid process that has an endpoint. It is a dynamic process that may need modification or adjustment over the life of the product. HASS Testing Benefits:
• Assures Manufacturing process and workmanship integrity.
• Verifies integrity of mechanical interconnects and component tolerance compatibility.
• Identify and preclude escape of potential early life product failures.
• Decrease product infant mortality, and increase reliability.
• Detect & correct design & process changes.
• Detect & correct component variation.
• Reduce production time & cost.
• Increase out-of-box quality & field reliability.
• Decrease field service & warranty costs.
• Find Manufacturing Process Problems