Optimisation of a surface mount technology process using a SnAgCu lead-free alloy

The impending introduction of lead-free solder in the manufacture of electrical and electronic products has presented the electronics industry with many challenges. European manufacturers must transfer from a tin-lead process to a lead-free process by July 2006 as a result of the publication of two directives from the European Parliament. Tin-lead solders have been used for mechanical and electrical connections on printed circuit boards for over fifty years and considerable process knowledge has been accumulated. Extensive literature reviews were conducted on the topic and as a result it was found there are many implications to be considered with the introduction of lead-free solder. One particular question that requires answering is; can lead-free solder be used in existing manufacturing processes? The purpose of this research is to conduct a comparative study of a tin-lead solder and a lead-free solder in two key surface mount technology (SMT) processes. The two SMT processes in question were the stencil printing process and the reflow soldering process. Unreplicated fractional factorial experimental designs were used to carry out the studies. The quality of paste deposition in terms of height and volume were the characteristics of interest in the stencil printing process. The quality of solder joints produced in the reflow soldering experiment was assessed using x-ray and cross sectional analysis. This provided qualitative data that was then uniquely scored and weighted using a method developed during the research. Nested experimental design techniques were then used to analyse the resulting quantitative data. Predictive models were developed that allowed for the optimisation of both processes. Results from both experiments show that solder joints of comparable quality to those produced using tin-lead solder can be produced using lead-free solder in current SMT processes.

Statistical Characteristics of Flash Flood in Georgia

Results are presented from the analysis of observations data on flash flood in Georgia over a period of 45 years, from 1961 to 2005, provided of the of Hydro-meteorology Service of Georgia.

Bioclimatic Characteristics of Recreational Zones – Important Component of the Passport of the Health Resort – Tourist Potential of Georgia

მოყვანილია საკურორტო-ტურისტული პოტენციალის პასპორტის ძირითადი მაჩვენებლების აღწერილობა. განსაკუთრებული ყურადღება ეთმობა ბიოკლიმატურ პარამეტრებს. მოყვანილია პრაქტიკული მაგალითები აღნიშნული პარამეტრების გამოყენებისა საქართველოს ზოგიერთი საკურორტო-ტურისტული რაიონების ბიოკლიმატური პირობების შესაფასებლად.

Comparative Characteristics of Light Ions Content in the Urban and Ecologically Clean Locality in Georgia

The results of the stationary and expeditionary investigations of the light ions content in surface boundary layer in the urban and ecologically clean locality for different regions of Georgia are represented.

Qualitative and quantitative formal model-based safety analysis : push the safety button

Magdeburg, Univ., Fak. für Informatik, Diss., 2011

Transitions to fatherhood in East Germany in the 1990s : psychological determinants of childbearing and the meaning of entering into parenthood for young adults from Rostock ; an event-history and qualitative composite investigation within the Rostock longitudinal survey

East Germany, men, fertility, first births, event history analysis, problem-centered interviews, methodical integration, triangulation, social psychology, gender

Financial structure choice in owner-managed firms : entrepreneurial characteristics, utility of control, and the competitive context

Magdeburg, Univ., Fak. für Wirtschaftswiss., Diss., 2011

Integrationsverhalten innerhalb multiethnischer Teams in Einrichtungen der stationären Altenhilfe : eine qualitative Untersuchung in Bayern

Magdeburg, Univ., Fak. für Geistes-, Sozial- und Erziehungswiss, Diss., 2011

Experimental investigation of heat transfer characteristics from arrays of free impinging circular jets and hole channels

Free Tube Jet - Impingemenet - Heat Transfer - Arrary - Infrared Techuique - Hole Channels - Heat Transfer Uniformaty

Characteristics of the P2Y 11 nucleotide receptor : ligand binding characteristics and P2Y 11-P2Y 1 receptor

Purinergic receptors, nucleotides, P2Y, diastereoselectivity, potency, mutagenesis, ligand recognition, heterooligomerization, endocytosis, co-pulldown

A study of some characteristics of vegetable oils, by James B. McNair.

v.9:no.2(1930)

Vaterschaft heute : Einstellungen und Erfahrungen ; Qualitative Befunde zu Interviews mit engagierten Vätern

[s.c.]

Die Kulturelle Bildung von Kindern und Jugendlichen am Stadttheater : eine quantitative und qualitative Betrachtung zur Relevanz des Stadttheaters für die Kulturelle Bildung am Beispiel des Anhaltischen Theaters Dessau

[s.c.]

Was Kinder im Alter von sechs bis zehn Jahren über Partizipation denken : eine qualitative Untersuchung

[s.c.]

Die Rezeption von Kundenzeitschriften gesetzlicher Krankenkassen : Eine qualitative Untersuchung am Beispiel des „Gesundheitstelegramms“ der IKK gesund plus

Kundenmagazine sind ein wichtiges Instrument des Marketing und der Öffentlichkeitsarbeit. Dies haben auch die gesetzlichen Krankenkassen erkannt. Im Rahmen des Wettbewerbs nutzen sie ihre Kundenzeitschriften zur Mitgliedererhaltung. Wie aber werden diese Zeitschriften von ihrer Leserschaft rezipiert und welche Handlungsmotive liegen dem zugrunde? Im Rahmen einer qualitativen Untersuchung wurde dies anhand von Befragungen der Rezipienten des "Gesundheitstelegramms" der IKK gesund plus analysiert.