This proposal seeks funding for the Center for Advanced Vehicle and Extreme Environment Electronics (CAVE) located at Auburn University. Funding Requests for Fundamental Research are authorized by an NSF approved solicitation, NSF 10-601. The solicitation invites I/UCRCs to submit proposals for support of industry-defined fundamental research.
The objective of proposed research is to develop fundamental understanding of failure mechanics of extreme environment electronics under overlapping stresses of high temperature, cyclic thermal stresses, shock and vibration. The proposed research will target the development of methodologies for prediction of damage initiation and progression for multi-mode competing failure locations in and the vicinity of board-level interconnects. Fundamental understanding of the high-strain rate material and interface behavior will be developed under sequential and simultaneous exposure of stresses. Damage equivalence relationships and survivability envelopes will be developed using pre-cursors.
It is envisioned that the proposed research will result in development of key enabling methodologies which are scalable to a wide array of extreme environment applications. Examples include automotive and avionic systems which are subjected to simultaneous temperature and transient dynamic loads. Increased use of sensors and controls in automotive applications has resulted in significant emphasis on the deployment of electronics directly mounted on the engine and transmission. The broader impact and outreach activities will include, (a) Initiation of undergraduate students, women and under-represented minorities in research. (b) Partner with the Womens Leadership Institute at Auburn University (c) Organization of topical-session at the ASME Congress (IMECE) (d) Incorporation of research results in extreme environment applications in cooperation with leading manufacturers which are industrial members of the NSF Center for Advanced Vehicle Electronics (CAVE3). (f) Introduction of K-12 school children to electronics through lab tours and in-class presentations.
The industry is going through a transition in material sets for second level interconnects including adoption of leadfree solders. Electronic interconnects may experience high strain rates when subjected to shock and vibration. In this project the high strain rate properties of the commonly used leadfree solders including SAC105 and SAC305 have been measured to allow the modeling of electronics survivability under high strain rates at high operational temperatures. The Anand viscoplastic constitutive model has been widely used to describe the inelastic deformation behavior of solders in electronic components. The model needs nine parameters to describe material behavior. The nine parameters have been measured from stress-strain curves of solder alloys at various strain rates and temperatures. Measurements have been made at strain rates of 1-100 per sec and temperatures of 25, 50, 75, 100, 125°C. The data measurements in the project fill a critical void of scarce high strain rate properties of leadfree solder alloys. The fundamental technologies developed in the program have been applied to the development of a new design for the JEDEC test board for an Industry Consortium working as part of the JEDEC Working Group. The results have been used to eliminate the deficiencies of the existing JEDEC test board which is unable to impose a uniform strain field on the all the components on the test board and revise the test standard JEDEC JESD22-B111 which is used to assess the survivability of components under shock environments.