Package Material Selection Criteria for High Temperature Automotive Applications

In this paper, a structured approach is shown for the selection of reliable package materials for microelectronic devices to be applied in high-temperature automotive applications. The principles of Physics-of-Failures are followed in which the application use conditions play a leading role. Primary focus is on the 1st bond (contact from ball to bond pad). It will be shown that Au-wire has intrinsic capability which is limited by current density and direction. The alternative Cu-wire may have constraints too, because of its enhanced sensitivity for corrosion. Dependent on wire type, surrounding molding compound and temperature under use life application, two different corrosion mechanisms must be considered: galvanic corrosion (only present for Pd-coated Cu-wire) and interfacial Cu-Al intermetallic corrosion (occurring for all types of Cu-wire). Life time prediction models and material characterization are used to study the dynamics and physics of corrosion mechanisms during High-Temperature Operating Life, which is a reliability test intended to address all kind of degradation mechanisms in the silicon die itself in the first place. Finally, using the developed fundamental understanding, pros and cons of various material combinations will be discussed.