An Uprateability Risk Assessment Methodology

Abstract

Uprating is a process to assess the ability of a part to meet the functionality and performance requirements of the applications in which the part is used outside the manufacturers' specification range. However, uprating can be an expensive and time consuming process. There is also no guarantee that all parts can be successfully uprated.

In 2002, some electronic part manufacturers began releasing a category of parts considered to be "closer" to military-grade parts, called "Enhanced Plastic (EP)". Since some of the EP parts offer a wider operating temperature range compared with the commercial parts, they are promoted by the EP part manufacturers as an alternative to uprating.

This thesis evaluates the EP parts and finds that when EP parts are available in wider temperature range, they can be beneficial to the electronic system manufacturers as they do not require uprating. However, the availability of EP parts in wide operating temperature range is limited, and the cost is much higher.

The thesis then provides a priori methodology to evaluate the uprateability of an electronic part, and in particular, eliminate parts that are unlikely to be successful in uprating. Four uprateability risk levels are defined which can be determined from the available part and system information during the part selection process. The method of analyzing the information to assign the risk levels is developed for both active and passive parts.

Three case studies of uprateability risk assessment are then presented in the thesis - one for an operational amplifier and two for polymer film capacitors. Complete analysis beginning from manufacturer and part assessment through electrical test results analysis is performed to show the uprateability risk assessment process.