A solder ball shear and pull testing study was conducted on 27 unique package constructions, evaluated under a wide variety of test conditions. The study encompassed the coordinated efforts of 7 electronics manufacturers using earlyprototype high speed solder ball shear/pull equipment. Shear speeds ranged from a conventional 0.0001 m/s (100 µm/s) rate up to as high as 4 m/s, while pull testing ranged from speeds of 0.0005 m/s (500 µm/s) to 1.3 m/s. The many package configurations varied in substrate plating type (exposed Cu, electrolytic NiAu and electroless-Ni/immersion-Au), solder composition (SnPb, SnPbAg and SnAgCu), packaging construction and materials, solder and package geometries, package assembly location, and time between reflow and test.

This study investigated brittle solder joint failure mechanisms during high-speed solder ball shear and pull testing. BGA package samples with different solder alloys (Sn4.0%AgO.5%Cu and Sn37%Pb) were fabricated and a series of solder ball shear and pull tests were conducted at various testing speeds. The ball shear test speeds ranged from 10 mm/s to 3000 mm/s, while the ball pull test speeds ranged from 5 mm/s to 500 mm/s. Following high-speed shear/pull testing, the brittle fracture surfaces of the solder balls and corresponding pad were inspected using SEM/EDX. The results describe an increased incidence of brittle interfacial fracture for SnAgCu solder compared to SnPb solder. Microstructure analysis of brittle solder joint fracture surfaces appears an effective method to aid correlation between board level drop test and high-speed solder ball shear/pull tests.

High-velocity electromagnetic sheet-metal forming and processing has many potential advantages over more conventional techniques, including: higher-forming limits, resistance to wrinkling and springback, one-sided tooling, and physical contact to only one side of the work piece. Traditional electromagnetic actuators are flat spirals that produce a nonuniform pressure distribution, limiting the types of parts that can be formed. A new type of electromagnetic actuator, the uniform pressure (UP) actuator, has been developed. The UP actuator can uniformly and efficiently accelerate conductive sheet metal to velocities on the order of 200 m/s or greater over distances of a few millimeters. When the material is arrested by impact with a tool, high-forming pressures can be imparted to it. The utility of the UP actuator is illustrated here by demonstrating its ability to form sheet metal components with intricate shape, to shock harden, and also to pick up nearly arbitrarily small details from a die surface. Thus, electromagnetic processing with the use of the UP actuator offers the unprecedented ability to simultaneously form and engineer the surface morphology and microstructure of sheet metal samples.

No abstract

With a growing number of low-income patients developing Congestive Heart Failure in urban Denver, accessible and affordable solutions are needed to provide home management options. A multidisciplinary team evaluated currently available options for telemonitoring and developed a solution for an initial pilot study. This system is currently used in the Denver Metro area (Colorado) for 44 CHF patients. Preliminary results show this approach is effective and has reduced the patients' average length of stay at the hospital compared to historical data and control patients who do not use a remote monitoring system.