CAREER: Novel Environmentally-Benign Solders for Electronic Packaging: Thermomechanical Behavior and Characterization

Arizona State University, Scottsdale AZ

Investigators

Abstract

0092530 Chawla This CAREER program examines novel, environmentally benign solders in bulk form and at small length scales. The research plan includes experimental investigations coupled with computational modeling of the mechanical behavior and microstructure of promising Pb-Sn solder replacement alloys (Sn-Cu, Sn-Ag, and Sn-Ag-Cu). The role of evolution of microstructure, including coarsening of the solder microstructure and solder/substrate interactions, is examined with respect to the creep and thermal fatigue behavior. The evolution of microstructure is modeled using the novel, microstructure-integrated, Object Oriented Finite Element Method (OOF), recently developed at the National Institute for Standards and Technology (NIST). Novel micromechanical testing techniques will be developed to characterize thermomechanical behavior at the solder ball level. Conventional FEM techniques, using accurately measured constitutive behavior derived from micromechanical testing, will be used to develop life prediction methodologies. In addition, an outreach program will be implemented through the Office for Minority Engineering Students (OMEP) and the Women in Science and Engineering (WISE) program at Arizona State University. High school teachers will spend a summer in the PI's laboratory to gain experience with cutting edge research. Also, part-time students from industry will take part in new and revised courses dealing with the subject of materials for electronic packaging, including physical and mechanical metallurgy of solders. %%% Given the widespread use of Pb-Sn solder in the manufacture and assembly of circuit boards, the development and reliability of new Pb-free solders is crucial for the successful substitution of these materials in the electronic systems. The subject of Pb-free solders is of great interest to local companies such as Intel, Motorola, and Onsemiconductor and close interaction with industry is expected throughout the course of this career development program. It is believed that the education outreach effort will contribute to an increase in the number of undergraduate students majoring in materials science. This is particularly important given the high demand for engineers with materials backgrounds in the microelectronic packaging industry. ***