Thermal shock resistance of flat plastic integrated circuit packages

Flat packages (FPs) were formed from epoxy molding compounds with various physical properties using a transfer molding machine. The compounds were prepared by changing kinds and amounts of additives and addition methods. The thermal shock test was carried out by the following procedures. The plastic package was soaked alternately in liquid nitrogen (?196°) and in liquid solder (200°) in the cycle of 140s. The median life to crack initiation was defined to be the cycles when half of the specimens exhibited crack initiation. According to linear fracture mechanics, the following expression was obtained relating the median life N, thermal stress σ_t, and strength σ_b; N = C/σ·(σ_b/σ_t)^m. We found the linear relation between logarithm of Nσ and logarithm of σ_b/σ_t for various packages, and estimated the values of C and m as 5 × 10⁴ MPa² and 5.5, respectively. The value of m was the same as that obtained for a dual-in-line package.     

Separation of Polyvinyl Chloride from Plastic Mixture by Froth Flotation after Surface Modification with Ozone

Selective modification by ozonation for the surface of polyvinyl chloride (PVC) was evaluated to separate PVC from the other plastics, polyethylene terephthalate (PET), polycarbonate (PC) and polymethyl methacrylate (PMMA), with almost the same density as PVC by the froth flotation process. Ozonation could selectively decrease the contact angles of flexible PVC from 87.5 degrees to 68.4 degrees and rigid PVC from 90.3 degrees to 66.9 degrees, whereas little decreases in the contact angle were observed for other plastics. This would be due to the replacement of the chloride group on the surface of PVC, into hydrophilic functional groups; carbonyl, carboxyl and ester group. The PVC was successfully separated from the other plastics by the froth flotation process after the selective surface modification by ozonation.     

Yield of OH radicals in water under heavy ion irradiation. Dependence on mass, specific energy, and elapsed time

Dependence of yields of OH （hydroxyl） radicals on the mass and specific energy of heavy ions and elapsed time after irradiation was investigated, to understand chemical reactions of aqueous solutions. The yields of irradiation products of phenol, super-linearly increased with the incident energy of He, C, and Ne ions ranging from 2 to 18 MeV/u. The yields of the OH radicals were estimated by analyzing the yields of the irradiation products of phenol. The yields of the OH radicals increased with the specific energy for each ion, but decreased both with the mass of each ion at the same specific energy and elapsed time after irradiation.     

Application of electron beam for the reduction of PCDD/F emission from municipal solid waste incinerators

The electron-beam technology was applied to reduce the emission of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in a flue gas of 1000 m(3)N/h from the municipal solid waste incinerator (MSWI) at a temperature of 200 degrees C. More than 90% decomposition of PCDD/Fs was obtained using an electron accelerator at a dose of 14 kGy. The decomposition was initiated through reactions with OH radicals produced by the irradiation of flue gases, followed by oxidation such as the ring cleavage of the aromatic ring, the dissociation of ether bond, and dechlorination. The cost analysis estimated that the electron-beam system can cut the annualized cost by approximately 50% for the treatment of PCDD/Fs in a pre-dusted MSWI flue gas as compared with a bag-filter system when operating on electricity generated from an incineration. Electron-beam technology is an economically and technologically useful method for reducing PCDD/Fs in an incineration flue gas.     

Terephthalic acid synthesis at higher concentrations in high‐temperature liquid water. 2. Eliminating undesired byproducts

We synthesized terephthalic acid (TPA) from p‐xylene at an initial concentration above its solubility limit in high‐temperature liquid water (HTW). The nominal p‐xylene loading at the reaction conditions was 0.4 mol L^?1, which is the highest reported to date for generation of high TPA yields (>70 mol %) in HTW. The presence of two liquid phases during the reaction did not appear to accelerate the rate, unlike behavior reported for some other organic reactions done “on water” at lower temperatures. Adding oxygen gas in a large increment during synthesis produced a black liquid and a black solid byproduct, which is a previously undocumented problem. Adding oxygen in smaller increments prevented formation of the liquid and solid byproducts and also provided high selectivities (90 mol %) and yields (>70 mol %) of TPA. These results demonstrate the feasibility of HTW as a medium for TPA synthesis at p‐xylene concentrations even higher than its solubility limit. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Space charge field effect on light emitting from tetracene field-effect transistor under AC electric field

By applying square wave AC voltage to the Au source electrode of tetracene based field-effect transistor (FET), electroluminescence (EL) was obtained. The results suggest that electrons and holes were injected alternately from the source electrode and recombined each other, and lead to the EL. This type of EL was localized at the interface between the source electrode and tetracene, and enhanced periodically with two relaxation times in accordance with the applied AC voltage cycle. We modeled the carrier behavior in the FET and explained the decay of EL, taking into account the space charge field contribution. Finally, using an AC voltage superposed on DC bias voltage, it was shown that electron injection was prompted only by space charge field.     

Japanese expectations for green building assessments

The background and feedback on the Green Building Challenge '98 process in Japan is provided by a representative from one of two Japanese teams (representing the Building Constructors' Society). The positive process of validating and adapting the international criteria to particular national circumstances and then customizing these criteria is explained. Three significant benefits to the Japanese building industry are discussed: existing technologies and methodologies were validated, it was discovered that these have potential for world-wide application, the life expectancy of Japanese buildings needs to be lengthened. Future expectations from Japan include: the ongoing refinement of the international framework for the environmental assessment of buildings; the customization of criteria requires further structure and limits, a critical review of the customization process; an expansion embracing both developed and developing nations' new and existing buildings. The prototype green building assessment from GBC '98 has the potential to be refined and adopted as a world-wide methodology and is endorsed as the fastest way to achieve world-wide consensus. Les generalites et le retour d'informations se rapportant au projet Green Building Challenge 98 au Japon sont fournies par un representant de l'une des deux equipes japonaises (association de constructeurs). Cet article s'interesse a la procedure positive de validation et d'adaptation des criteres internationaux a des circonstances nationales specifiques puis leur particularisation. L'auteur examine egalement trois avantages significatifs pour l'industrie japonaise du batiment: le GBC a permis de valider des technologies et des methodologies existantes; on a decouvert qu'elles recelaient un potentieal pour une application mondiale; la duree de vie des batiments japonais doit etre allongee. On attend egalement du Japon des contributions dans les domaines suivants: l'affinage, deja en cours, du cadre international de l'evaluation environnementale des batiments; l'adaptation des criteres exige une autre structure ainsi que des limites; une revue critique du procede d'adaptation; une expansion englobant les batiments nouveaux et existants dans les pays en developpement et dans les pays industrialises. Le prototype d'evaluation des batiments verts a partir du projet GBC 98 peut etre affine et adopte sous forme d'une methodologie mondiale et etre considere comme la methode la plus rapide pour aboutir a un consensus global.     

Solid polymerization and supramolecular chirality formation of azobenzene substituted diacetylene Langmuir–Blodgett films

An azobenzene mesogen-substituted diacetylene (NADA) monolayer has been transferred onto the solid substrate by the traditional Langmuir–Blodgett (LB) method. Solid-state polymerization of NADA LB films can be sensitized in visible light region. In situ UV–vis absorption measurement enables us to study polymerization kinetics of NADA LB films. The polymerization process can be described as a first order rate equation and polymerization rate constants are characterized in detail. Furthermore, achiral NADA molecules can form chiral LB films through overcrowded packing of the azobenzene moiety.     

Self‐Powered Trace Memorization by Conjunction of Contact‐Electrification and Ferroelectricity

Triboelectric nanogenerator (TENG) is a newly invented technology that can effectively harvest ambient mechanical energy from various motions with promising applications in portable electronics, self‐powered sensor networks, etc. Here, by coupling TENG and a thin film of ferroelectric polymer, a new application is designed for TENG as a self‐powered memory system for recording a mechanical displacement/trace. The output voltage produced by the TENG during motion can polarize the dipole moments in the ferroelectric thin film. Later, by applying a displacement current measurement to detect the polarization density in the ferroelectric film, the motion information of the TENG can be directly read. The sliding TENG and the single‐electrode TENG matrix are both utilized for realizing the memorization of the motion trace in one‐dimensional and two‐dimensional space, respectively. Currently, the ferroelectric thin film with a size of 3.1 mm² can record a minimum area changing of 30 mm² and such resolution can still be possibly improved. These results prove that the ferroelectric polymer is an effective memory material to work together with TENG and thereby the fabricated memory system can potentially be used as a self‐powered displacement monitor.