This award provides continued support for the Industry/University Cooperative Research Center for Advanced Vehicle Electronics (CAVE) at Auburn University. The objective of the center is to perform research on new technologies for the packaging and manufacturing of harsh environment electronics, with special emphasis on the reliability and cost requirements of the vehicle industry. The research thrusts of the Center in the harsh environments area include robust packaging and interconnection technologies, modeling methodologies, damage mechanics, material behavior and failure mechanisms, design procedures, accelerated testing methodologies, field-life correlations, and manufacturing processes. The Center puts its research in the hands of practitioners through technology transfer mechanisms including software tools, and design guidelines.
A NATIONAL SCIENCE FOUNDATION INDUSTRY/UNIVERSITY COOPERATIVE RESEARCH CENTER SINCE 1999 Research for cost-effective electronics manufacturing and packaging technologies for high-reliability electronics in a harsh environment CENTER MISSION AND RATIONALE The electronics used in such automotive, aerospace, and military vehicles are subjected to more challenging application environments than those present in the computer and telecommunication sectors. The CAVE3 Center is built around commonality of themes related to electronic systems in the automotive, military, defense, aerospace and space-based applications. The focus of the center research is on innovation in design, reliability, prognostics, and manufacturability of electronics for future emergence of cost-effective, damage tolerant electronic systems. Electronics in harsh environments typical of automotive, military, defense, aerospace and space-based applications may be subjected to severe high and/or low ambient temperatures; extreme temperature changes; moisture and high humidity; exposure to dirt, contaminants, chemicals, and radiation; and excessive transient loadings, shock/drop, and vibration. EMI/RFI (Electro Magnetic Interference /Radio Frequency Interference) shielding from internal and external noise, and ESD (Electro Static Discharge) are also critical factors. Commercial off-the-shelf technologies may not address the reliability and life-cycle needs of the extreme environment applications. These themes provide the motivation for the Center’s strategic directions related to technology development and research resource allocation. RESEARCH PROGRAM Research areas in CAVE3 covered in member company and externally funded projects emphasized development of innovative technologies for high-reliability needed in harsh environment applications (e.g. extreme high or low temperatures, large temperature swings, high vibration and drop/impact, and high humidity). Components and Assemblies: In this research area, reliable component packaging technologies (BGA, CSP, 3D Packaging, QFN, etc.) were developed for harsh environments such as automotive under-the-hood and aerospace applications and also for portable electronic products such as cell phones. The primary objective was to develop fundamental knowledge on the interactions between component design and material selection on package reliability and thermal performance in harsh thermal cycling and vibration environments. Specific contributions include development of accelerated tests data, guidelines on the selection and use of components in harsh environments for various electronic structures including but not limited to - metal backed boards, high Tg laminates; crack propagation and damage models; thermal cycling reliability data; algorithms for prognostication; computational models for reliability and thermal performance; design guidelines and decision support tools; and models for shock, drop, and vibration. Prognostics and Diagnostics: Leading indicators-of-failure have been developed for interrogation of material state significantly prior to appearance of any macro-indicators. The research focus is on determination of residual life of electronic systems via on-board sensing, damage-detection algorithms and data processing. Environments being studied include single, sequential, simultaneous thermo-mechanical, hygro-mechanical and dynamic loads. PHM is a key enabling technology with applications to avionic, automotive, and bio-implantable electronic systems, Connectors and System-Level Interconnects: In this research area, the effects of vibration and environment on the performance of automotive and other harsh environment connectors were evaluated. The primary goals were to examine connector interconnection options for next generation extreme environment applications and to establish the reliability and failure mechanisms. A basic understanding of the causes of fretting corrosion was established, and then utilized to develop strategies for the accelerated testing of connectors. In addition, the growth of tin whiskers is being studied on connector pins with lead free plating finishes. Research included both fundamental studies on the origin of whisker growth and experimental test matrices to examine next generation connector designs. Deliverables from connector reliability research include design guidelines, modeling tools, reliability data, and processing recommendations. Flip Chip and Underfills: In this research area, materials and processes were explored for flip chip on laminate, flip chip BGA packaging, CSP (redistributed die, Ultra-CSP, etc.) assemblies deployed in extreme thermal cycling environments. The primary objective was to develop a fundamental understanding of the reliability of flip chip applications in harsh environment applications and High End Microprocessor Packaging. Study next-generation materials (Nano-structured underfills, High-Reliability STABLCOR Substrates, Thermal Interface Materials, Chip-Level Interconnects). Project deliverables included design and material guidelines for flip chip packages used in the automotive thermal cycling environment; material properties and adhesion characteristics of underfill encapsulants; flip chip thermal cycling reliability data; assembly and manufacturing processing recommendations; and finite element and material models for application to future package designs. Lead Free Soldering: In this research area, potential lead-free solder alloys and corresponding lead-free surface finishes (board and component) were studied to replace eutectic 63Sn-37Pb solder in harsh environment applications. The primary goal was to develop a fundamental understanding of alternate solder alloys that will meet the high reliability, and high volume low cost manufacturing needs of the vehicle industry. Deliverables included recommendations on solder alloys; solderability (wetting) measurements; thermal cycling reliability data, stress-strain and creep results as a function of temperature, constitutive and solder fatigue models; and processing recommendations.
