Fluorinated poly(arylene ether sulfone)s for polymeric optical waveguide devices

Pentafluorophenyl sulfone was prepared by oxidation of pentafluorophenyl sulfide. Ethynyl terminated fluorinated poly(arylene ether sulfone) (EFPAESO) was synthesized via nucleophilic aromatic substitution from 4,4′-(hexafluoroisopropylidene) diphenol or 4,4′-(trifluoromethylphenylisopropylidene) diphenol with an excess of pentafluorophenyl sulfone, followed by reaction with 3-ethylnylphenol. The molecular weights (M_ns) of the polymers determined by GPC with polystyrene standard were in the range of 6,400-17,200 and polydispersities (M_w/M_ns) were in the range of 2.25-3.19. This EFPAESO showed very high thermal stability up to 479 °C for 5% weight loss in TGA in air. T_g of the polymer was changed from 148 to 196 °C after curing. The cured films showed good chemical resistance and high thermal-stability. At 1550 nm wavelength, the refractive indices of the copolymer films were in the range of 1.5037-1.5504 and birefringences were in the range of 0.0021-0.0025. The optical loss for EFPAESO was less than 0.37 dB/cm at 1550 nm wavelength.     

Effects of laser parameters on the characteristics of a Sn-3.5 wt.%Ag solder joint

Microstructure and shear strength were assessed for a Sn-3.5 wt.%Ag solder joint formed using a laser heat source. A continuous wave Nd:YAG laser was used to make the Sn-3.5 wt.%Ag solder joint. Solder balls of 400μm diameter were used and the laser beam spot diameter at focus was approximately 120μm. The UBM (Under Bump Metallurgy) on a FR4-PCB consisted of Cu/Ni/Au from bottom to top with a thickness of 15μm/5μm/0.05μm, respectively. In order to position solder balls on the UBM, RMA (rosin mildly activated) type flux for a BGA (Ball Grid Array) was used. Selected optimal conditions were as follows: a laser power of 2W and heating time of 0.3 s, 0.5 s, and 0.7 s; a laser power of 3 W and heating time of 0.1 s and 0.3 s; and a laser power of 4 W and a heating time of 0.1 s. Under all conditions, the shear strengths of the solder joint of (CuNi)₃Sn₄ at the interface between the pad and solder were larger than 554.37 gf (i.e. the shear strength obtained from hot plate reflow). When the laser power was set at 2 W, the microstructure of IMC (intermetallic compound) was recrystallized regularly due to active convection, which was caused by increased heating time. Under a laser power of 4 W and heating time of 0.7 s, the microstructure was recrystallized irregularly due to violent convection caused by excessive energy input (=laser power (W) ×heating time (s)). The IMC layer increased in thickness as a result of increasing the energy input, and was affected by laser power more than by heating time.     

Electrodeposition of the Sn-58 wt.%Bi layer for low-temperature soldering

The electroplating characteristics and deposition layer of a Sn-Bi eutectic alloy applicable to low-temperature soldering were investigated. A methane sulphonate electrolyte was fabricated and the current density was focused in order to achieve an eutectic Sn-Bi composition. The electroplating characteristics, including the polarization curve and deposition thickness with plating time, were also studied. As experimental results, a polarization curve showed a Sn-Bi codeposition occurred under a −0.5 V electropotential. The Bi content in the Sn-Bi deposit decreased with an increasing current density, such as 99.42 wt.% for −10 mA/cm² and 42.27 wt.% for −40 mA/cm². The thickness of the electroplated layer increased with the plating time, while a relatively uniform thickness was obtained in a short plating time, such as less than 40 min. The eutectic deposition of Sn-58.2 wt.%Bi was successfully fabricated by plating at −30 mA/cm² for 30 min.     

Ambient Temperature Ultrasonic Bonding of Si-Dice Using Sn-3.5wt.%Ag

Ultrasonic bonding of Si-dice to type FR-4 printed circuit boards (PCB) with Sn-3.5wt.%Ag solder at ambient temperature was investigated. The under-bump metallization (UBM) on the Si-dice comprised Cu/Ni/Al from top to bottom with thicknesses of 0.4 μm, 0.4 μm, and 0.3 μm, respectively. The pads on the PCBs consisted of Au/Ni/Cu with thicknesses of 0.05/5/18 μm, sequentially from top to bottom. Solder was supplied as Sn-3.5wt.%Ag foil rolled to 100 μm thickness, and inserted in the joints. The ultrasonic bonding time was varied from 0.5 s to 3.0 s, and the ultrasonic power was 1400 W. The experimental results showed that reliable joints could be produced between the Si-dice and the PCBs with Sn-3.5wt.%Ag solder. The joint breaking force of “Si-die/solder/FR-4” increased with bonding times up to 2.5 s with a maximum value of 65 N. A bonding time of 3.0 s proved to be excessive, and resulted in cracks along the intermetallic compound between the UBM and solder, which caused a decrease in the bond strength. The intermetallic compound produced by ultrasonic bonding between the UBM and solder was confirmed to be (Cu, Ni)₆Sn₅. An erratum to this article can be found at     

Electrochemical and structural characteristics of metal oxide-coated lithium manganese oxide (spinel type): Part I. In the range of 2.5–4.2 V

The electrochemical and structural characteristics of the metal oxide-coated spinel were investigated in the range of 2.5–4.2 V. Metal oxide coating on commercial spinel powder (LiMn_2−xM_xO₄, M=Zr, Nikki, Japan) was carried out using the sol–gel method. Al₂O₃/(PtO_x or CuO_x)-coated spinel exhibited improved cyclability compared to bare spinel. Impedance analysis results indicated that electrochemical resistance value was not consistent with cycle performance. The improved cycle performance of metal oxide-coated spinel may be due to formation of a new Li₂Mn₄O₉, Li₂MnO₃ phase, which is expected to have stability to phase transition (Jahn–Teller distortion).     

Protective effect of bioactive ceramics on liver injury: regulation of pro-inflammatory cytokins expression

Aim of study A bioactive ceramics has been reported to regulate the expression of inflammatory cytokines in macrophage cells activated by lipopolysaccharides (LPS). In present study, we investigated the anti-inflammatory effect of bioactive ceramics using liver injury model in mouse. Materials and Methods Mice were divided into three groups: Normal group, LPS group (LPS and no ceramics treatment), Ceramics group (LPS and ceramics treatment). Results LPS administration induced the increase of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in mouse. The losses of cytoplasm of hepatocytes due to LPS caused the increase of AST and ALT in mouse plasma. In Ceramics group, however, the concentration of AST and ALT were much lower than LPS group until 6 weeks. And the losses of cytoplasm were rarely seen in Ceramics group. RT-PCR results showed that the decrease of proinflammatory cytokines such as IL-1β and IL-6 was observed in Ceramics group. Moreover, TGF-β1 and VEGF expression was increased in Ceramics group. Conclusion Bioactive ceramics effectively protected endotoxin-induced liver injury by attenuation of inflammatory processes in mice.     

Low-loss fluorinated poly(arylene ether sulfide) waveguides withhigh thermal stability

Some novel cross-linkable fluorinated poly(arylene ether sulfides) (FPAESI) were synthesized for use in optical waveguide applications. The materials have high thermal stability, high optical transparency in the infrared communication region, and much less birefringence than other thermally stable fluorinated polyimides. The refractive index of FPAESI after storage at 100°C for 1000 h remains almost constant, demonstrating their thermal stability. Furthermore, the refractive index of the material can be easily controlled by changing the fluorine content of the materials. The propagation loss of channel waveguides, which were fabricated using reactive ion etching was less than 0.42 dB/cm and 0.4 dB/cm at the wavelength of 1.55 μm for TE and TM polarizations, respectively