Designs with space-grade devices must consider the variances in values that can occur over time, which is especially true for resistor aging.

Designs requiring space-grade components must take into account the variances in component values that can occur over time. This is especially true for resistors, which can exhibit significant changes over their lifetime. Unfortunately, while most public guidelines for estimating resistor aging are reasonably conservative, the issue is designers are following typical data and advertising hype and not the actual limits that vendors are allowed to deliver to.

Given there aren’t too many suppliers of space-grade resistors, and that MIL-PRF-55342 establishes specifications for resistors, the variance that different companies use in the aging tolerances and guidelines for resistors is quite surprising. Over the years, in the WCCA we have performed, we have seen everything from 0.1% to 4% for the aging/combined environments tolerance term, often referred to as just aging. Reconsider using 0.5%, or even 1%, for MIL-PRF-55342 resistor end-of-life effects; it is probably not supportable.

For more information visit https://www.electronicproducts.com/a-deep-dive-into-guidelines-for-resistor-aging/