IPACK2007-33269 STUDY OF HEAT TRANSFER IN MICROSCALE SYSTEMS

ABSTRACT Progress in micromachining technology enabled fabrication of micron-sized mechanical devices, which have had a major impact on many disciplines. These devices have not only led to development of miniature transducers for sensing and actuation, but also a chip-based chemical laboratory (μChemLab) and other microelectromechanical systems (MEMS). Applications of these microscale systems frequently demand heat removal and temperature control. This paper presents preliminary results of a study of heat transfer in microscale systems. Computational modeling is based on Thermal Analysis System (TAS), which facilitates multiscale modeling/simulation, and measurements are made using infrared (IR) microscopy. Representative applications describe multiscale modeling and measurement results obtained for a microhotplate of a μChemLab and a highpower GaAs FET amplifier. Comparison of the preliminary experimental/measurement and computational/modeling results shows good correlation

THERMOMECHANICAL EFFECTS IN PACKAGING: MATCHING CTE OR NOT?

ABSTRACT Development of effective packages for microelectronics, MEMS, as well as for other microsystems and advanced modern devices, is usually based on minimization of thermomechanical effects and maximization of the useful life of a package. Such extremization-analysis depends on the effects that coefficients of thermal expansion (CTEs) have on the design of packages. This paper examines thermomechanics of a package and evaluates the effects that matching (or not) of CTEs may have on a package and its life. This examination is illustrated with representative examples

Regulated complex assembly safeguards the fidelity of Sleeping Beauty transposition

The functional relevance of the inverted repeat structure (IR/DR) in a subgroup of the Tc1/mariner superfamily of transposons has been enigmatic. In contrast to mariner transposition, where a topological filter suppresses single-ended reactions, the IR/DR orchestrates a regulatory mechanism to enforce synapsis of the transposon ends before cleavage by the transposase occurs. This ordered assembly process shepherds primary transposase binding to the inner 12DRs (where cleavage does not occur), followed by capture of the 12DR of the other transposon end. This extra layer of regulation suppresses aberrant, potentially genotoxic recombination activities, and the mobilization of internally deleted copies in the IR/DR subgroup, including Sleeping Beauty (SB). In contrast, internally deleted sequences (MITEs) are preferred substrates of mariner transposition, and this process is associated with the emergence of Hsmar1-derived miRNA genes in the human genome. Translating IR/DR regulation to in vitro evolution yielded an SB transposon version with optimized substrate recognition (pT4). The ends of SB transposons excised by a K248A excision(+)/integration(-) transposase variant are processed by hairpin resolution, representing a link between phylogenetically, and mechanistically different recombination reactions, such as V(D)J recombination and transposition. Such variants generated by random mutation might stabilize transposon-host interactions or prepare the transposon for a horizontal transfer