Thermal Fatigue of Solder Joints

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Funding is provided under this RUI award to permit 8 teams of undergraduatestudents over the course of a two-year period to participate in a continuousresearch project evaluating the thermomechanical fatigue of solder joints. Tomake this experience successful it is proposed to create a unique learningexperience which is a combination of innovative classroom instruction andresearch. A master's student will assist in this project, and by doing so have aunique master's level experience designed to require the evaluation of the workof others, the synthesis of their work with that of the undergraduates and thedevelopment of leadership skills. There are research and teaching components tothis proposed project.Research: Thermomechanical fatigue (TMF) is the leading cause of solder jointfailure in electronic assemblies. TMF of solder joints is difficult to model asthere are many complex and interacting factors effecting the progression ofdamage to the joint. Because of the high homologous temperatures (0.8 or higher)significant microstructural evolution occurs during TMF, changing the propertiesof the material as TMF progresses. An experimentalinvestigation will be conducted to 1) identify those more readily measured materialproperties most likely to affect TMF resistance, 2) evaluate the variousacceleration factors used in TMF testing, and 3) evaluate the role of wetting inTMF failures.As a result of this research much insight into TMF failure will be gained - 1)progress will be made toward the development of an experimentally verifiedenergy model, and 2) the role of wetting in adhesion will be assessed. Thismeans that those considering using lead-free solder alloys will be able to usediagnostic "tools" not currently available -- the combination of materialproperties which correlate to TMF resistance.Teaching: To enable undergraduates to participate in a continuing researchprogram, a unique "classroom" experience will supplement the research. Theseclass sessions will embrace interactive learning techniques, and expose theundergraduates to 1) the necessary theoretical background, 2) the status of theproject, 3) necessary lab techniques including statistical analysis, 4) oral andwritten communication skills, and 5) broader issues including ethics andeconomic impact. All of these subjects will be context based. The philosophy ofthis course is that upper level undergraduates need to perform at the synthesislevel of Bloom's Taxonomy, and their experience is designed to enable them to doso.The master's student will be required to perform at the evaluation level ofBloom's Taxonomy (evaluating the work of the undergraduates) and synthesize thiswork with their own study on wetting, thus participating in a unique integratingexperience. Additionally the student will develop leadership skills, andpossibly be persuaded to pursue a doctoral degree and develop a desire to teach.The master's students experience may also encourage the undergraduates to pursuea graduate degree.It is felt that this comprehensive plan will maximize the chances for successand serve as a demonstration project for others desiring to incorporate researchinto the undergraduate experience and developing a novel masters program.Impact: It is felt that this program can significantly impact undergraduateeducation by serving as a proof of concept in the development of researchoriented courses, generating an appreciation of life-long learning, anddemonstrating the value of undergraduate research to the outside community. Thiswork complements the current work of the PI and lays the foundation for hisfuture plans.