Hiroyoshi Kawasaki

Synthesis of Novel Spiro[indol-2,2′-pyrroles] Using Isocyanide-Based Multicomponent Reaction

Abstract An efficient and facile method for the synthesis of novel spiro[indole-2,2′-pyrroles] from N-methyl-3-isatin imines, t-butyl isocyanide, and dialkyl acetylenedicarboxylate has been achieved by [3 + 2] cyclo addition reaction. All the products were purified by column chromatography as yellow solids and confirmed with 1H NMR, 13C NMR, fast atom bombardment, mass, and infrared. Compound 11 was further confirmed with x-ray analysis. GRAPHICAL ABSTRACT

Energy Dependent Efficiency in Low Background Alpha Measurements and Impacts on Accurate Alpha Characterization

A difference in low emissivity alpha particle measurements for the same samples was observed between an Alpha Sciences model 1950 gas proportional counter and the XIA UltraLo-1800 ionization chamber. The energy dependent efficiency was evaluated for each instrument to reconcile the difference, and the implication of instrument design bias on measurement results is presented.

Improving self-alignment effect of Cu balls by organic and inorganic surface coating

A good correlation between the thickness of oxidation layer of Cu balls and their movement on the solder bumps has been found out, suggesting that non-oxidized Cu balls without no oxygen atmosphere could be a good condition in terms of self-alignment in packaging. We have succeeded in developing novel coated Cu balls that can be stored under mild conditions.

Cu balls and Cu-core balls for 3D packaging

The use of Cu balls and Cu-core balls is focused on 3D packaging technology to maintain a stable standoff height. However, these materials show unique soldering behaviors that are different from solder balls. In this paper, we examine how to utilize them.