Low-modulus die-bonding films (reaction-induced polymer alloy films) are useful for stacked multi-chip packages which are suitable for compact electronic devices. Properties of the films are widely changed by the ratio of epoxy resin and acrylic polymer contents. To optimize the properties of the die-bonding films for thin wafer application, the influence of various parameters on material properties was examined by using the linear programming method for materials design. The film designed by the programming showed excellent adhesion strength and shelf life.

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The influence of styrene contents on the hardening reaction of unsaturated polyester resins was studied. The degree of cross-linking in the resins with different styrene contents was estimated by solid-NMR analysis, laser Raman analysis and quantitative analysis of organic acid by sub-critical water hydrolysis method. We also measured the density and glass transition point of the resins. The degree of cross-linking in the resins estimated by these methods was nearly the same. Although the cross-linking reaction increased with an increase in styrene contents, the hardening reaction didn't proceed at the styrene content above about 70%. Moreover, the molecular weight of the styrene-fumaric acid copolymer that was produced by sub-critical water hydrolysis, increased with an increase in styrene contents, suggesting that the sequence length of the styrene residues in the cross-linking of the resins also increased with increasing styrene contents. The decreases in the density and glass transition temperature of the resins with an increase in styrene contents are correlated to the decrease in the cross-link density of the resins, namely the increase in the average distance between the cross-linking points.

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In the fields of optical materials such as flat panel displays, transparent resins must show a low thermal expansion and a high heat resistance. In this study, a transparent resin with a low thermal expansion has been successfully prepared by dispersing a high content of colloidal silica into the resin. The measurement of synchrotron radiation small-angle X-ray scattering indicated that the silica particles of a high content in the resin were uniformly arranged in the packing structure predicted by the paracrystal theory. These results suggest that a highly regular arrangement of silica particles may lead to an increase in the light transmittance of the resins.

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Chemical structures in acrylate-type ultra violet (UV) -cured resins were characterized using specific sample decomposition. At first the cured resin sample was analyzed by pyrolysis-gas chromatography (Py-GC) in the presence of organic alkali, tetramethylammonium hydroxide (TMAH) . A series of products, not only those of the constituent monomers and prepolymers, but also methyl acrylate (MA) and its oligomers (up to hexamers) reflecting the cross-linking sequences, which were formed through thermally assisted hydrolysis and methylation selectively occurred at ester linkages in the UVcured resins, were observed in the pyrograms. These products were interpreted in terms of the chemical composition and molecular weight of the constituent monomers (prepolymers) , their double bond conversion in curing, and the sequence distributions of network junctions. Moreover, the UV cured resins were also characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis of the samples. The methanolysis products were fractionated by size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The observed distributions of the decomposition products suggested that the network junctions in the UV-cured resin were composed of up to around 2,000 acrylate units.

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In order to use polymers as optical materials in various devices, such as flat panel displays, optical discs, optical lenses and optical fibers, ideal optical characteristics including transparency, refractive index, etc., must be achieved. We have clarified the quantitative relationship between the essential optical properties of polymers and the chemical structure of a repeating unit, in order to predict optical properties only from the chemical structure of the unit. This review describes the quantitative prediction of the refractive index of polymers from their chemical structure. This prediction system is useful for the molecular design of optical polymers.

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Synopsis: Three-dimensional (3D) bicontinuous structures of binary polymer blends and block copolymers, selfassembling during the phase separation processes and/or the phase transition, have been directly observed using an emerging technology, i.e., “three-dimensional microscopy”. The 3D complicated morphologies were clearly observed by either laser scanning confocal microscopy (LSCM) or by transmission electron microtomography (TEMT). A great deal of new structural information, which has never been obtained from conventional microscopy or various scattering methods, can be evaluated from the 3D volume data. The structural information obtained from 3D microscopy offers essential insight into the physics of non-linear non-equilibrium phenomena and the statistical mechanics of long chain molecules.

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