Dissolution and intermetallic compound (IMC) layer development were examined for couples formed between 99.9 silver (Ag) and molten 95.5Sn-3.9Ag-0.6Cu (wt pct), 99.3Sn-0.7Cu, and 63Sn-37Pb solders, using a range of solder temperatures and exposure times. The interface reactions that controlled Ag dissolution were sensitive to the solder composition. The Ag 3 Sn IMC layer thickness and interface microstructure as a whole exhibited nonmonotonic trends and were controlled primarily by the near-interface solder composition. The kinetics of IMC layer growth were weakly dependent upon the solder composition. The processes of Ag dissolution and IMC layer growth were independent of one another.

Declining numbers of students majoring in computer science coupled with the rapidly growing aging population are both causes for concern in society. Computer science majors have diminished since 1986, but recent thrusts of happenings focus on encouraging students towards a STEM degree. One in every three senior citizens dies with some form of dementia with the percentages on the rise. This population is often forgotten, but research shows the elderly can be stimulated with technology as evidence with music and memory programs. Combining advancement in computer science and technology to design and develop products that can facilitate the lives of many senior citizens was found important.The combination of computer science and real-world situation is a good way to stimulate students in getting their hands on the problems our society is facing. Programming in support of real-world social issues causes the students to relate in various ways, invigorates students not only to learn programming skills, but also acquire knowledge beyond the typical level and pace. Appealing to student interests in helping others, including possible relatives, foster experiential learning outside the classroom that potentially supports life-changing projects and assists with needs in society. In this project, students develop a mobile app for Android and iOS platforms as a team including usability for a documentary called Alive Inside, created to help those with Alzheimer's disease and dementia improve their quality of life. This mobile app will stimulate the memory of those suffering of Alzheimer and dementia through music of their youth. This paper will report on student experiences, techniques, products delivered, and overall outcomes.

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The microstructure and rate kinetics were investigated for solid-state intermetallic compound (IMC) layer growth in Sn-Ag-Cu/Ag and Sn-Pb/Ag couples. The aging temperatures were 55°C to 205°C and 70°C to 170°C, respectively. The aging times were 1 day to 400 days. The SnAg-Cu/Ag IMC layer included the phases: Ag 3 Sn (dominant), the f phase, and a solid-solution phase, xAg-ySn, (94 to 96 at. pct Ag). Void formation was observed at the solder/IMC (Ag 3 Sn) interface, which was attributed to the Kirkendall effect. The rate kinetics of IMC layer growth were expressed through t n exp(-DH/RT). The values of n and DH for the IMC layer phases were:(1) f + xAg-ySn, n = 0.68 ± 0.23, DH = 59 ± 15 kJ/mol; (2) Ag 3 Sn, n = 0.22 ± 0.05, DH = 28 ± 2 kJ/mol; and (3) total layer, n = 0.34 ± 0.06, DH = 45 ± 3 kJ/mol. The very low DH value for Ag 3 Sn suggested a very fast, fast-diffusion mechanism. The IMC layer of SnPb/Ag couples was predominantly the Ag 3 Sn stoichiometry. The IMC layer growth was accompanied by the development of a Pb-rich phase layer at the solder/IMC interface. There was insignificant void development in these couples. The rate kinetics parameters, n and DH, were 0.44 ± 0.06 and 51 ± 4 kJ/mol, respectively, indicating a traditional fast-diffusion mechanism.