No abstract

No abstract

No abstract

This paper presents a global–local methodology for predicting mechanical deformation and fatigue durability of solder joints in electronic packaging systems subject to cyclic thermal loading. It involves a global deformation analysis, a local critical solder–joint analysis, and a fatigue life analysis. The global deformation analysis includes a new optimization formulation for determining an equivalent model. The methodology developed was applied to fine pitch ball grid array (fpBGA) and super ball grid array (SBGA) packages. Selective experimental efforts were also undertaken to evaluate the predicted deformation characteristics of the fpBGA package. A good agreement was obtained between the simulated deformation results and experimental observations. For the durability analysis, the total fatigue life predicted using the energy-based method is larger than 2500 cycles—a trend observed experimentally for both packages entailing widely different designs. Based on proposed modeling and simulation results and package designs studied, the SBGA package is more durable than the fpBGA package.

Magnesium-dependent adenosine triphosphatase (ATPase) activity of unfixed, isolated, in tact skeletal muscle mitochondria, frozen-thawed mitochondria and digitonin-disrupted submitochondrial particles was localized ultrastructurally after incubation in a Wachstein-Meisel reaction medium and correlated with chemical ATPase activity. The reaction precipitate was localized within the matrix of intact and partially disrupted mitochondria and between membranous fragments in the submitochondrial particles. These findings are consistent with an ATPase activity residing within the headpieces of the elementary particles ol mitochondrial cristae with deposition of reaction precipitate within the adjacent matrix.