Development of a Rapid Fatigue Life Testing Method for Reliability Assessment of Flip-Chip Solder Interconnects

The underlying physics of failure are critical in assessing the long term reliability of power packages in their intended field applications, yet traditional reliability determination methods are largely inadequate when considering thermomechanical failures. With current reliability determination methods, long test durations, high costs, and a conglomerate of concurrent reliability degrading threat factors make effective understanding of device reliability difficult and expensive. In this work, an alternative reliability testing apparatus and associated protocol was developed to address these concerns; targeting rapid testing times with minimal cost while preserving fatigue life prediction accuracy. Two test stands were fabricated to evaluate device reliability at high frequency (60 cycles/minute) with the first being a single-directional unit capable of exerting large forces (up to 20 N) on solder interconnects in one direction. The second test stand was developed to allow for bi-directional application of stress and the integration of an oven to enable testing at elevated steady-state temperatures. Given the high frequency of testing, elevated temperatures are used to emulate the effects of creep on solder fatigue lifetime. Utilizing the mechanical force of springs to apply shear loads to solder interconnects within the devices, the reliability of a given device to withstand repeated cycling was studied using resistance monitoring techniques to detect the number of cycles-to-failure (CTF). Resistance monitoring was performed using specially designed and fabricated, device analogous test vehicles assembled with the ability to monitor circuit resistance in situ. When a resistance rise of 30 % was recorded, the device was said to have failed. A mathematical method for quantifying the plastic work density (amount of damage) sustained by the solder interconnects prior to failure was developed relying on the relationship between Hooke’s Law for springs and damage deflection to accurately assess the mechanical strength of tested devices

Resurrecting a Witch: An Intimate Look at the Roles Faith and Politics Played During the Salem Witchcraft Trials of 1692

This work deals with the roles faith and politics played in the hearts and minds of those people who were caught up in the mass hysteria of the Salem Witchcraft Trials of 1692. It examines the trials through the colored lenses of several of Salem\u27s accused, their accusers, and the men who served as their judges. It focuses on the mishandling of the accused witches at both their hearings and trials, and how the purported visions seen by their accusers were often used as the sole evidence to indict, try, sentence, and hang many of the accused. Resurrecting a Witch does not claim to explain why Salem happened, rather it gives us a unique insight into the motivations behind the accusations of several of Salem\u27s accused witches. Furthermore, it intimately details the aftermath of Salem on the lives of two individuals who played key roles in the trials, and how that experience reshaped their hearts and brought them to regret their role in Salem\u27s injustices. Yet, the work does not end there, it also brings to the forefront a lesson for people today on what havoc can be wrought when misguided fear is paired with selfish desire. For Salem, this mixture of fear and desire would result in persons of faith who were willing to blindly accuse their neighbors of crimes they did not commit rather than to see themselves faced with that same fate. Resurrecting a Witch opens our eyes to the darker side of the human psyche, one that protects itself at all cost, even if the cost paid is the life of friend or even a member of our own family

Soils of the Ozark region : a preliminary report on the general character of the soils and the agriculture of the Missouri Ozarks

June 1910.Digitized 2007 AES

Historical Hispanic partisan alignments, Hispanic outreach styles, and the theory of Hispanic surge-and-decline effects on Hispanic peripheral voters

Over the last decade, the Hispanic voting community has emerged as one of the most important demographic groups in United States politics, especially in recent presidential elections. Yet there has been very little research conducted on Hispanic voter turnout and voting behavior. When it comes to theories of minority voting behavior, resource theories significantly fail to capture the total dynamics of minority group voting behavior and turnout. For example, Hispanics have lower SES resources, such as education and income, relative to Anglos, but so do African-Americans, yet African-Americans vote at significantly much higher rates than Hispanics. One logical explanation as for why these models fail to explain fully Hispanic turnout behavior is the fact that almost all the research conducted has been on Anglos. This researcher proposes a new Hispanic voter model, a theory of Hispanic surge-and-decline effects on peripheral Hispanic voters, that adds the concept of self-activation vis-a-vis group consciousness to resource and mobilization explanations. This theory is analyzed using recent San Antonio Mayoral elections, New Mexico Gubernatorial elections and Colorado Senatorial elections. Time series analyses and multiple linear regression analyses are utilized to study precinct-to-the-same-precinct and county-to-the-same-county net change in turnout between elections. The results of these analyses strongly support the surge-and-decline theory. Specifically, Hispanic surges are tied to increases in peripheral Hispanic voters, and when viable Hispanic candidates seek office, Hispanic turnout increases significantly relative to both Anglo turnout and baseline Hispanic turnout, and when no viable Hispanic runs for office, Hispanic turnout decreases relatively. This has profound future implications. If the Republican and Democratic parties want to attract more Hispanic voters for their respective candidates, then these parties must recruit, run and support viable Hispanic candidates at all levels of government, including candidates the Vice Presidency and the Presidency. Based on the theory of Hispanic surge-and-decline effects, this researcher posits that the first party to select a viable Hispanic Vice Presidential candidate, and ultimately a viable Presidential candidate, will be the party that realigns the majority of Hispanic voters for at least three to four decades.Governmen

THE INFLUENCE OF MEDIATING VARIABLES ON MEMBER SATISFACTION AND EFFECTIVENESS IN GROUP DECISION MAKING

Abstract not availabl

The Effects of Upper Surface Modifications on Low Reynolds\u27s Flight

The research conducted was focused on manipulating the upper surface boundary layer over an airfoil through controlling transition. This control would prove beneficial for low Reynold’s flight by reducing the pressure drag on airfoil, which could significantly improve the efficiency of small unmanned aerial vehicles. The models used in testing contained two different types of upper surface modifications. The first set was based around a series of circular extrusions, the circles were varied by size, depth, and spacing. The second set of models were based on a triangular ramp similar to that of a NACA inlet, the ramps were varied by size, depth, and spacing. The results of testing thus far has shown that the model with the deepest circular extrusion experiences a shift in its zero angle of attack while the model with the greatest distance between circles illustrated an early reattachment of the separated flow. Testing of the NACA inlets is still under way, although some preliminary results show that certain models have their lowest drag at a point where positive lift is being generated. Ignite Grant Awar