HALT & HASS Technology
HALT & HASS technology uses proactive techniques designed not only to measure the reliability of the product, but to improve it. The methods are proactive in that one seeks out weaknesses in the product using extreme controlled overstress conditions in HALT testing prior to production release. Somewhat lower levels of controlled overstress conditions are incorporated in HASS during production to quickly expose manufacturing process flaws.
The stresses applied in HALT and HASS are not meant to simulate the field environments, but are meant to expose the weak links in the design and processes using only a few units and in a very short period of time. The stresses are stepped up to well beyond the expected field environments until the “fundamental limit of the technology” is reached in robustness. Reaching the fundamental limit generally requires improving everything relevant found even if found above the “normal qualification” levels! This means that one ruggedizes the product as much as possible without unduly spending money. Only those failures that are likely to occur in normal environments, are relatively easy to fix, or add cost to HASS are addressed. Skills and experience must be used during analysis. Otherwise, one could easily overcompensate and make the product much more rugged than required, spending unnecessary money in the process.
Cost of Fixing a Design Defect * Savings Factor
- $35 during design 19,712:1
- $177 before procurement 3,898:1
- $368 before production 1,875:1
- $17,000 before shipment 41:1
- $690,000 on customer site 1:1
The goal is to find and fix relevant issues in house, not allowing them to become expensive field issues!!
* From EuroPACE Quality Forum , Hiroshi Hamada, President, Ricoh
References: Accelerated Reliability Engineering, Gregg K. Hobbs, Hobbs Engineering, 2005.