| The continuous miniaturization of electronic packages and systems combined with ever-decreasing product development cycles requires continuous refinement of the analytical and numerical models that are used as design tools and to predict the durability of products subjected to field or laboratory conditions. As the interconnect length scales approach the alloy microstructural feature sizes, the need to incorporate such small-scale parameters becomes more urgent. Likewise, shorter product development cycles combined with downward cost pressure necessarily restricts the time and resources available for carrying out experimental verification of product durability, consequently increasing the reliance on simulations for design validation. Solder interconnects have traditionally been and continue to be a weak link in most conventional electronic packages, so a more complete understanding of these materials is highly desirable. Furthermore, alternative interconnect materials, including those for high-temperature, lead-free and multi-stage processing applications, have only recently been studied and have been subjected to only the most basic characterization studies.; In this dissertation, the durability of two solder interconnect alloys, the standard Sn63Pb37 eutectic and an important lead-free alloy, is investigated using a combination of experimental and analytical techniques. A miniature, solid state, mechanical testing system is developed to provide a means for the testing in shear of solder alloy specimens with length scales similar to those seen in typical interconnects. Cyclic, durability tests are conducted over suitable ranges of amplitude, deformation rate and temperature using multiple test control algorithms; monotonic and load-controlled tests are also conducted at different temperatures and load levels. Macro-scale constitutive and durability behavior of the solder alloy can be observed and modeled directly from the basic experimental data (i.e. load and displacement histories). Localized behavior of the test solder joints is inferred from numerical analysis of the test structures and conditions.; In addition, several test durability test approaches and methodologies are evaluated. The effects of using different test control algorithms on durability modeling, consequences due to choice of failure definition, and the effect of accounting for the complete cyclic load history instead of traditional initial cycle metrics are examined. |
