Thermosonic ball bonding is the most popular method used to create electrical interconnects between integrated circuits (ICs) and substrates in the microelectronics industry. Traditionally gold (Au) wire is used, however with industry demands for lower costs and higher performance, novel wire materials are being considered. Some of these wire materials include Cu, insulated, and coated wires. The most promising of which being Cu wire. Some of the main issues with these wire materials is their performance in the electrical flame off (EFO) step of the wire bonding process. In the EFO step a ball called the free air ball (FAB) is formed on the end of the wire. The quality of the FAB is essential for reliable and strong ball bonds. In Cu wire bonding the hardness of the FAB and oxidation are the main issues. A hard FAB requires larger bonding forces and US levels to make the bond which increases the likelihood of damage to the IC. Excessive oxidation acts as a contaminant at the bond interface and can also influence the shape of the FAB. Shielding gases are required to reduce oxidation and improve FAB quality. This thesis focuses on the EFO process and the influence of EFO parameters and shielding gases on Au and Cu FABs. The primary focus of this thesis is to provide a better understanding of the EFO process in order to expedite the introduction of novel wire materials into industry. Several different experiments are performed on an automated thermosonic wire bonder with 25 µm Au and Cu wires to investigate the EFO process during ball bonding. The effects of EFO parameters on the hardness and work hardening of FABs and the effects of shielding gas type and flow rates on the quality of the FABs are determined. The EFO discharge characteristics in different shielding gases is also studied to better understand how the composition of the atmosphere the FAB is formed in influences the energy input via the EFO electrical discharge. Using the online deformability method and Vickers microhardness testing it is found that the EFO current (IEFO) and EFO time (tEFO) have a large influence on the hardness and work hardening of Au and Cu FABs. A harder FAB produced with a large IEFO and low tEFO will work harden less during deformation. The bonded ball will be softer than that of a FAB produced with a lower IEFO and higher tEFO. The online deformability method is found to be twice as precise as the Vickers microhardness test. An online method for characterizing the quality of FABs is developed and used to identify shielding gas flow rates that produce defective FABs. The EFO process for an Au wire and two Cu wire materials is investigated in flow rates of 0.2-1.0 l/min of forming gas (5 % H2 + 95 % N2) and N2 gas. All three of the most common FAB defects are identified with this online method. It is found that good quality FABs cannot be produced above flow rates of 0.7 l/min and that H2 in the shielding gas adds a thermal component to the EFO process. It is recommended that the gas flow rate be optimized for each new wire type used. The EFO discharge power is measured to be 12 % higher in a N2 gas atmosphere than in a forming gas atmosphere. The lower ionization potential of the forming gas leads to a higher degree of ionization and therefore lower resistance across the discharge gap. It was found that the discharge power does not determine the energy transferred to the wire anode because the Au FAB produced in forming gas has a 6 % larger diameter than that of the FABs produced in N2 gas. Other factors that effect the voltage of the EFO discharge include the controlled EFO current, the discharge gap, and the wire anode material.

No description available.

The purpose of this study was to explore, from readily available data, the best predictors of medical claims costs at Ball State University (BSU). Multiple regression equations were developed to predict BSU's medical claims costs from selected demographic and health-related measures among 1,799 BSU employees. The predictors were chosen from data previously collected during the three-year study period: July 1, 1995 to June 30, 1998. Regression equations were developed for the entire BSU population and the high-cost population. The linear composite of number of emergency room visits, number of chronic health problems, gender and age predicted 17.86% of the variation in transformed medical claims costs for the entire BSU population. The linear composite of age, number of emergency room visits and gender predicted 9.95% of the variation in transformed medical claims costs for high-cost BSU employees. Logistic regression, performed on the entire BSU population, did not differentiate low and highcost employees well: only 15.0% of high-cost employees were classified correctly. / Fisher Institute for Wellness

The purpose of this study was to examine the relationship between Expected Family Contribution as determined by the Free Application for Federal Student Aid process and college student persistence to graduation at Ball State University.The population for this study was defined as 3,772 Ball State University full-time students who matriculated in the fall of 1995. The sample equaled the population. In response to the research question, the sample was divided into five subgroups (Full-Pell, Partial-Pell, No Pell-Need, No Pell-No Need, and No-FAFSA).It was determined that students at Ball State University with greater financial need (Full-Pell and Partial-Pell) persist and graduate at smaller rates than students in the other financial subgroups. In addition, students with high financial need are more likely to academically disqualify than other students. Statistically significant differences existed between the average rates for graduation and academic disqualification, and the graduation and academic disqualification rates for the Full-Pell and Partial-Pell groups. Institutions may need to determine if they are meeting the financial and academic needs of students from low-income families. / Department of Educational Leadership

The purpose of this study was to examine the computer habits and involvement of residential freshmen matriculates at Ball State University to determine if there was a difference in campus involvement levels between students who excessively used the computer for personal or recreational activities and students who did not.The project consisted of 149 non-excessive users (five or less hours per week) and 323 excessive users (more then five hours per week) of the computer for the personal or recreational purposes. Freshmen matriculates were involved in a wide range of opportunities. The higher levels of involvement were from opportunities in Residence Hall, Welcome Week, and UniverCity categories.The findings also indicated that excessive computer users were involved as much as non-excessive users. The amount of time students spent on computers for personal or recreational purposes did not deter students from being involved during their first semester at Ball State University. / Department of Educational Leadership

This dissertation examined the annual Women’s Week events hosted by Ball State’s Women’s and Gender Studies Program. It served to paint a historical picture of how the local Muncie community has been linked with the academic community at Ball State through events about women’s issues. The program began when a group of people wanting to broaden the educational offerings and evolved into an academic program that brings community education related to women’s issues to the Ball State campus. This research used qualitative research interview with four key informants to examine the community links and history of Women’s Week at Ball State University by answering two specific research questions. The participants described their roles in the Women’s Week events from organizing the program to presenting about their lifelong passions. Many of the discussions were fond recollections, but challenges were also brought to light. Presenting relevant topics and maintaining student involvement were two subjects mentioned by the informants. Improvising and long term planning were also emphasized. / Department of Educational Studies

I Sverige finns cirka 80 000 identifierade förorenade områden som i vissa fall behöver efterbehandling för att hantera föroreningssituationen. Naturvårdsverket publicerade 2009 ett reviderat vägledningsmaterial för riskbedömningar av förorenade områden tillsammans med en beräkningsmodell för att ta fram riktvärden. Riktvärdesmodellen är deterministisk och genererar enskilda riktvärden för ämnen under givna förutsättningar. Modellen tar inte explicit hänsyn till osäkerhet och variabilitet utan hanterar istället det implicit med säkerhets­faktorer och genom att användaren alltid utgår från ett rimligt värsta scenario vid val av parametervärden. En metod för att hantera osäkerhet och variabilitet i riskbedömningar är att göra en så kallad probabilistisk riskbedömning med Monte Carlo-simuleringar. Fördelen med detta är att ingångsparametrar kan definieras med sannolikhetsfördelningar och på så vis hantera inverkan av osäkerhet och variabilitet. I examensarbetet genomfördes en probabilistisk riskbedömning genom en vidare egen implementering av Naturvårdsverkets metodik varefter probabilistiska riktvärden beräknades för ett antal ämnen. Modellen tillämpades med två parameter­uppsättningar vars värden hade förankrats i litteraturen respektive Naturvårdsverkets metodik. Uppsättningarna genererade kumulativa fördelningsfunktioner av riktvärden som överensstämde olika mycket med de deterministiska riktvärden som Naturvårdsverket definierat. Generellt överensstämde deterministiska riktvärden för markanvändningsscenariot känslig mark­användning (KM) mer med den probabilistiska riskbedömningen än för scenariot mindre känslig markanvändning (MKM). Enligt resultatet i examensarbetet skulle dioxin och PCB-7 behöva en sänkning av riktvärden för att fullständigt skydda människor och miljö för MKM. En fallstudie över ett uppdrag som Geosigma AB utfört under hösten 2013 genomfördes också. Det var generellt en överensstämmelse mellan de platsspecifika riktvärden (PRV) som beräknats i undersökningsrapporten och den probabilistiska risk­bedömningen. Undantaget var ämnet koppar som enligt studien skulle behöva halverade riktvärden för att skydda människor och miljö. I den probabilistiska riskbedömningen kvantifierades hur olika skyddsobjekt respektive exponeringsvägar blev styrande för olika ämnens riktvärden mellan simuleringar. För några ämnen skedde avvikelser jämfört med de deterministiska motsvarigheterna i mellan 70-90 % av fallen. Exponeringsvägarnas bidrag till det ojusterade hälsoriskbaserade riktvärdet kvantifierades också i en probabilistisk hälsoriskbaserad riskbedömning. Riktvärden med likvärdiga numeriska värden erhölls för riktvärden med skild sammansättning. Detta motiverade att riktvärdenas sammansättning och styrande exponeringsvägar alltid bör kvantifieras vid en probabilistisk riskbedömning. / In Sweden, approximately 80,000 contaminated areas have been identified. Some of these areas are in need of remediation to cope with the effects that the contaminants have on both humans and the environment. The Swedish Environmental Protection Agency (EPA) has published a methodology on how to perform risk assessments for contaminated soils together with a complex model for calculating soil guideline values. The guideline value model is deterministic and calculates single guideline values for contaminants. The model does not account explicitly for uncertainty and variability in parameters but rather handles it implicitly by using safety-factors and reasonable worst-case assumptions for different parameters. One method to account explicitly for uncertainty and variability in a risk assessment is to perform a probabilistic risk assessment (PRA) through Monte Carlo-simulations. A benefit with this is that the parameters can be defined with probability density functions (PDFs) that account for the uncertainty and variability of the parameters. In this Master's Thesis a PRA was conducted and followed by calculations of probabilistic guideline values for selected contaminants. The model was run for two sets of PDFs for the parameters: one was collected from extensive research in published articles and another one included the deterministic values set by the Swedish EPA for all parameters. The sets generated cumulative probability distributions (CPDs) of guideline values that, depending on the contaminant, corresponded in different levels to the deterministic guideline values that the Swedish EPA had calculated. In general, there was a stronger correlation between the deterministic guideline values and the CPDs for the sensitive land-use scenario compared to the less sensitive one. For contaminants, such as dioxin and PCB-7, a lowering of the guideline values would be required to fully protect humans and the environment based on the results in this thesis. Based on a recent soil investigation that Geosigma AB has performed, a case study was also conducted. In general there was a correlation between the deterministic site specific guideline values and the CPDs in the case study. In addition to this, a health oriented risk assessment was performed in the thesis where unexpected exposure pathways were found to be governing for the guideline values. For some contaminants the exposure pathway governing the guideline values in the PRA differed from the deterministic ones in 70-90 % of the simulations. Also, the contributing part of the exposure pathways to the unadjusted health guideline values differed from the deterministic ones. This indicated the need of always quantifying the composition of guideline values in probabilistic risk assessments.

No description available.

No description available.

No description available.