Flip chip on board: assessment of reliability in cellular phone application

Flip chips are generally seen as a potential future "packaging" option providing an alternative to chip scale packages. In this work, the reliability of flip chip assemblies was analyzed using daisy chain test components on a schematic test vehicle designed to emulate a cellular phone environment printed wiring board (PWB). The flip chip components were assembled in a standard surface mount technology process, where the flip chip bumps were first dipped in a flux film. A test matrix consisting of a number of flip chip test components with different input/output configurations, PWBs, fluxes, and underfills was built up. The assemblies were tested for potential damage to the flip chips and their interconnects by thermal cycling and by mechanical shock in a drop. After testing, the root causes of the failures were analyzed. As a separate task, the stress/strain generation that occurs in the flip chips in the drop test was analyzed using simulation, in order to find the critical locations on the test PWB.     

Electrode Layout and Process Kinetics of Electroremoval of Copper from Sand

This research paper concentrates on the efficiency of electrokinetic remediation of copper contaminated sand employing different electrode material, number and spacing. By optimising the selection of suitable electrode materials, coupled with the application of the appropriate number of electrodes and electrode spacing, it is expected that the remediation time will be drastically reduced. In addition, the methodology being investigated in this study will reduce inefficiencies in electrical field distribution. The effect of various electrode materials such as silver and graphite, and the influence of changes in the number and the layout of the electrodes on the overall remediation efficiency and time was investigated and evaluated. Experiments with one, two and three one-dimensional anode system have proved that remediation efficiencies as high as 91% can be attained.     

Trihexyl(tetradecyl)phosphonium hexafluorophosphate as an promising Extractant for extractive desulfurization from liquid fuels

Experimental data on extractive desulfurization (EDS) of dibenzothiophene (DBT), thiophene, benzothiophene, and other substituted derivatives of sulfur from liquid fuel using trihexyl(tetradecyl)phosphonium hexafluorophosphate ([THTDP][PF₆]) have been presented. The Fourier transform infrared spectrophotometer, ¹H-NMR, ¹³C-NMR, and ³¹P-NMR analysis have been discussed for molecular confirmation, and conductivity, solubility, and viscosity analyses of ([THTDP][PF₆]) were investigated. The effects of time, temperature, S-compounds, ultrasonication, and recycling of ([THTDP][PF₆]) on DBT removal from fuel were examined. Also, desulfurization of real fuels and multistage extraction was also tested. The data and results provided the significant insights of phosphonium ionic liquids as a promising solvent for EDS.