Dynamic analysis of Flip-Chip Self-Alignment

Self-alignment of soldered electronic components such as flip-chips (FC), ball grid arrays (BGA) and optoelectronic devices during solder reflow is important as it ensures good alignment between components and substrates. Two uncoupled analytical models are presented which provide estimates of the dynamic time scales of both the chip and the solder in the self-alignment process. These predicted time scales can be used to decide whether a coupled dynamic analysis is required for the analysis of the chip motion. In this paper, we will show that for flip-chips, the alignment dynamics can be described accurately only when the chip motion is coupled with the solder motion because the two have similar time-scale values. To study this coupled phenomenon, a dynamic modeling method has been developed. The modeling results show that the uncoupled and coupled calculations result in significantly different predictions. The calculations based on the coupled model predict much faster rates of alignment than those predicted using the uncoupled approach.

Optoelectronic packaging interfaces for submicron alignment (OPISA) and the dynamics of laser spot weld formation

The work presented in this paper is part of the OPISA project. This is a collaborative research project between the University of Greenwich and Bookham Technology. This report describes some of the initial work undertaken towards the goal of investigating optoelectronic packaging where alignment issues between optical sources and fibers can arise as part of the fabrication process. The focus of this study is on charting the dynamics of laser spot weld formation. This paper introduces some of the initial simulation work that has been undertaken and presents a model describing a transient heat source applied from a laser pulse to weld a stainless steel sleeve and ferrule and the resulting weld formation

Constructive trusts, illegal purpose and locus poenitentiae

Analyses the Family Division decision in Q v Q on the competing claims of a father and son to beneficial ownership of a house in which the father sought to on a secret agreement entered into with his sons when transferring the property into their joint names, intended to subvert the inheritance tax rules on lifetime gifts by retaining the right to have the property transferred back to him, and the son relied on a later agreement with his brother to transfer the house into his sole name, in reliance on which he and his wife had acted to their detriment by paying for its upkeep and renovation.

Constructive thinking

Discusses the House of Lords ruling in Cobbe v Yeoman's Row Management Ltd on whether the doctrine of constructive trust, as an alternative to proprietary estoppel, could be invoked by a property developer under the Law of Property (Miscellaneous Provisions) Act 1989 s.2(5) where an agreement for the acquisition of an interest in land failed to comply with s.2(1), but where the developer had incurred expenditure obtaining planning permission to develop the property. Reflects on whether there are circumstances in which the courts will find a constructive trust in order to avoid the effects of s.2(1).

Oral agreements: estoppel, constructive trusts and restitution

Analyses the House of Lords judgment in Cobbe v Yeoman's Row Management Ltd in relation to claims by the prospective purchaser under an oral agreement for sale of a block of flats based on proprietary estoppel, a constructive trust and common law restitution brought against the owner of the property who sought to resile from the agreement after the purchaser had, at considerable expense, obtained planning permission to redevelop the property in reliance on assurances given by the owner that if permission was granted the sale would be honoured.

Constructive notice and independent legal advice: a study of lending institution practice

Cases on when lending institutions will be put on inquiry as to circumstances giving rise to presumption of undue influence, and results of research on lending practice of residential mortgage lenders in light of case law. [From Legal Journals Index]

Partition alignment in three dimensional unstructured mesh multi-physics modelling

Unstructured mesh codes for modelling continuum physics phenomena have evolved to provide the facility to model complex interacting systems. Parallelisation of such codes using single Program Multi Data (SPMD) domain decomposition techniques implemented with message passing has been demonstrated to provide high parallel efficiency, scalability to large numbers of processors P and portability across a wide range of parallel platforms. High efficiency, especially for large P requires that load balance is achieved in each parallel loop. For a code in which loops span a variety of mesh entity types, for example, elements, faces and vertices, some compromise is required between load balance for each entity type and the quantity of inter-processor communication required to satisfy data dependence between processors.