Rapid Assessment of BGA Fatigue Life Under Vibration Loading

Ball Grid Array (BGA) packages are a relatively new package type and have rapidly become the package style of choice. Much high density, high I/O count semiconductor devices are now only offered in this package style. Designers are naturally concerned about the robustness of BGA packages in a vibration environment when their experience base is with products using more traditional compliant gull or J leaded surface mount packages. Because designers simply do not have the experience, tools are needed to assess the vibration fatigue life of BGA packages during early design stages and not have to wait for product qualification testing, or field returns, to determine if a problem exists. This dissertation emphasizes a rapid assessment methodology to determine fatigue life of BGA components. If time and money were not an issue, clearly one would use a general-purpose finite element program to determine the dynamic response of the printed wiring board in the vibration environment. Once the response of the board was determined, one would determine the location and value of the critical stress in the component of interest. Knowing the critical stress, one would estimate the fatigue life from a damage model. The time required building the FEA model, conducting the analysis, and post-process the results would take at least a few days to weeks. This is too time-consuming, except in the most critical applications. It is not a process that can be used in everyday design and what-if simulations. The rapid assessment approach proposed in this research focuses on a physics of failure type approach to damage analysis and involves global and local modeling to determine the critical stress in the component of interest. A fatigue damage model then estimates the life. Once implemented in software, i.e. the new version of CALCE_PWA, the entire fatigue life assessment is anticipated to be executed by an average engineer in real time and take only minutes to generate accurate results

NASA Tech Briefs, January 1999

Topics include: special coverage sections on sensors and data acquisition and sections on electronic components and circuits, electronic software, materials, mechanics, bio-medical physical sciences, book and reports, and a special section of Photonics Tech Briefs

NASA Tech Briefs, November 1990

Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

NASA Tech Briefs, January 1990

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NASA Tech Briefs, February 1998

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NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 13)

This issue of the Index Section contains entries for 3386 patent and application for patent citations covering the period May 1969 through June 1978. The Index Section contains five indexes --- subject, inventor, source, number, and accession number

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NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 14)

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A subject index is provided for over 5600 patents and patent applications for the period May 1969 through June 1994. Additional indexes list personal authors, corporate authors, contract numbers, NASA case numbers, U.S. patent class numbers, U.S. patent numbers, and NASA accession numbers