EAGER: Fracture of Microelectronic Lead Free Solder Joints under Dynamic Loading Conditions

Washington State University, Pullman WA

Investigators

Abstract

TECHNICAL ABSTRACT With the proliferation of mobile electronics in everyday life, the ability of electronic packages to sustain impact loading under drop conditions has become a paramount reliability concern. Therefore, the fracture behavior of solders at high strain rates is a critically important design parameter. A new methodology is proposed for mixed-mode fracture toughness testing of elasto-plastic adhesive joints under dynamic conditions. It is further proposed that this methodology be used to generate fundamental mechanistic insight into the role of several microstructural/process and test variables on the fracture of solder joints, including the effects of solder pad finish, aging, interfacial intermetallic structure, strain rate, mode-mixity and electromigration effects. The work will be of substantial technological importance by developing a new dynamic joint fracture testing methodology which will be eventually transferred to industry. Secondly, the work will be of substantial fundamental importance in generating new mechanistic insights into the role of microstructure on dynamic fracture, and by developing fracture mechanism maps that can be utilized in the design of new joining schemes for emerging chip/package interconnection architectures. NON-TECHNICAL ABSTRACT Mobile electronics such as PDAs, MP3 players and ultra-portable laptops are often dropped during use, making it important to build the electronic packages which constitute the brains of the system in a robust fashion. The tiny solder joints that constitute an important part of these packages are highly susceptible to fracture under drop conditions, and therefore, the fracture behavior of solders at high strain rates is a critically important design parameter. In the proposed work a new methodology will be developed for fracture testing of solder joints under drop conditions, and used to gain knowledge about how to design highly robust and reliable lead-free solder joints which will be much more resistant to drops than those currently available. This will lead to more reliable electronics with longer usable lifetimes.