Mathematical modelling: a laser soldering process for an optoelectronics butterfly package

For sensitive optoelectronic components, traditional soldering techniques cannot be used because of their inherent sensitivity to thermal stresses. One such component is the Optoelectronic Butterfly Package which houses a laser diode chip aligned to a fibre-optic cable. Even sub-micron misalignment of the fibre optic and laser diode chip can significantly reduce the performance of the device. The high cost of each unit requires that the number of damaged components, via the laser soldering process, are kept to a minimum. Mathematical modelling is undertaken to better understand the laser soldering process and to optimize operational parameters such as solder paste volume, copper pad dimensions, laser solder times for each joint, laser intensity and absorption coefficient. Validation of the model against experimental data will be completed, and will lead to an optimization of the assembly process, through an iterative modelling cycle. This will ultimately reduce costs, improve the process development time and increase consistency in the laser soldering process.

Estoppe right there

Examines the House of Lords judgment in Cobbe v Yeoman's Row Management Ltd on whether an experienced property developer was entitled to relief on the basis of proprietary estoppel for the cost of obtaining planning permission to demolish an existing property and build new houses under a non-binding oral agreement. Sets out two requisite conditions needed when deciding whether estoppel existed. Considers whether unconscionability was a separate element in making a claim for proprietary estoppel. [From Legal Journals Index]

Halfway to heaven

When some 700 people throng the auditorium at Earl’s Court to hear a debate about whether eco houses are ugly, then a frustrated tree-hugger like myself may feel that we are halfway to heaven, not that I plan to share my Elysium with Germaine Greer in ranting mode if I can avoid it.