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Courey, Karim

Publications and source records attributed to Courey, Karim.

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers

In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

Courey, Karim↗

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers-Part I

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance, electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data, we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB).

Courey, Karim↗

Automation of Design Engineering Processes

A method, and a computer program that helps to implement the method, have been developed to automate and systematize the retention and retrieval of all the written records generated during the process of designing a complex engineering system. It cannot be emphasized strongly enough that all the written records as used here is meant to be taken literally: it signifies not only final drawings and final engineering calculations but also such ancillary documents as minutes of meetings, memoranda, requests for design changes, approval and review documents, and reports of tests. One important purpose served by the method is to make the records readily available to all involved users via their computer workstations from one computer archive while eliminating the need for voluminous paper files stored in different places. Another important purpose served by the method is to facilitate the work of engineers who are charged with sustaining the system and were not involved in the original design decisions. The method helps the sustaining engineers to retrieve information that enables them to retrace the reasoning that led to the original design decisions, thereby helping them to understand the system better and to make informed engineering choices pertaining to maintenance and/or modifications of the system. The software used to implement the method is written in Microsoft Access. All of the documents pertaining to the design of a given system are stored in one relational database in such a manner that they can be related to each other via a single tracking number.

Torrey, Glenn↗