Stress testing to help systems designers qualify space parts

WASHINGTON — The trick of successfully using new Class T low-cost space components is reducing the design and fabrication costs while increasing testing and screening, says Joseph Benedetto, principal reliability engineer at UTMC Microelectronic Systems in Colorado Springs, Colo.

By John Rhea

WASHINGTON — The trick of successfully using new Class T low-cost space components is reducing the design and fabrication costs while increasing testing and screening, says Joseph Benedetto, principal reliability engineer at UTMC Microelectronic Systems in Colorado Springs, Colo.

Meanwhile, the key test is burn-in, which he calls essential for acceptable reliability. Benedetto made his comments in April at the COTScon East 2000 conference in Washington.

Benedetto also stresses the need to build product out of a homogenous wafer lot of material. "There's a lot of variation in the commercial world," he says, and these variations can be disastrous in terms of device latch-up and other failures.

Benedetto cites the traditional approach, in which the internal design costs about $1,000 per part, the dedicated radiation-hardened fabrication line adds $10,000 per wafer, and the back-end assembly and test amount to $100 to $200 per component.

UTMC's approach, which he calls QCOTS — short for qualified commercial off-the-shelf — reduces the design cost to less than $250 per part, cuts fabrication to $1,500 to $3,500 per wafer, and then spends more on the final assembly and test, which can run $200 to $500 per component.

The net result is cost saving and increased confidence of mission success through the process of quantifying the specific attributes of the COTS parts for spacecraft use. A "four nines" (99.99 percent) survivable probability is affordable at the radiation-hardened level, Benedetto says.

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