HASS - Proof Of Screen (POS)

Proof Of Screen is an essential part of the HASS Development process. Proving the HASS screen is not too strong to overstress 'good' hardware is the number goal of this stage. Once an appropriate screen is defined it must be run repetitively on known good production hardware a minimum of 15 times to ensure that good hardware will not be damaged during production screening.

Proof Of Screen - The Process

After deciding which screen type to apply during production it becomes necesary to prove that the screen will not damage 'good' production samples. The product will be loaded into the HALT chamber and configured as it would be if testing was being conducted during production. All fixturing should, ideally, be identical to that to be used in production.

The product is bolted to the vibration table using an appropriate fixture and all functional test equipment is connected before the Proof Of Screen begins. The proposed HASS screen is repeated a number of times. Each unit is tested throughout each cycle, and all failures must be driven to root cause in order to understand whether the failures are occurring due to overstress - or are actually dormant failures that would occur in the field, over time.

Why conduct Proof Of Screen?

After conducting Proof Of Screen you will have confidence that by running production hardware through the proposed HASS screen, no more than a minimum of 1/nth of the products overall life will have been used up. Determining the products life is not possible using HALT & HASS, and therefore standard reliability tests may be required to ensure this is an acceptable amount of life to lose.