Preemptive Testing Can Mitigate Cosmic Radiation Effects

Apr 1, 2010 12:00 PM
JAMES F. SALZMAN Director of Technology, High Reliability Group Texas Instruments, Dallas, Texas

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Testing parts for space applications can be difficult. First, test machines on Earth can't duplicate the exact effects encountered in space due to limited machine energy. Also, parts can't be tested over years to determine if they are usable in space. So, accelerated testing techniques are often used.

Accelerated testing techniques attempt to duplicate the effects of low-dose radiation rates where a part may be subject to over a 10- to 15-year mission in space. Techniques similar to those used in space can be misleading. In some cases, the same part subjected to low-dose rates can produce unexpected results compared with those tested at high-dose rates — a problem referred to as enhanced low-dose-rate sensitivity (ELDRS). This issue remains a discussion topic in many of today's radiation conferences and standards meetings.

Circuit technology also plays a major role in the effects of circuit performance in a high-radiation environment. Process technologies such as CMOS, Bipolar, GaAs, SiGe, and others all have pros and cons in the way they behave under various radiation effects. Understanding these behaviors is critical to the design of a high-reliability product with high tolerance to the various effects. When real-life measurements of certain conditions are not possible, measurements can be predicted based on only statistics and limited data.

Since test machines are limited in the type of particle energy they can produce, it is important to understand the environment in which your products will operate, as well as to ensure the circuits are reliable and tolerant to specific threats. Using HiRel products in systems that must be reliable helps to reduce the risk of system failure. Cutting corners to reduce costs potentially can jeopardize millions of dollars of space or avionic hardware. In the end, it really boils down to more than rocket science.