We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto...We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto mica substrates treated with MnCl 2 solution by electrostatic interaction, which forms a two-dimensional submonolayer. As shown by AFM study, the assembled process is size-selective, e.g., Ag particles assembled onto mica are more uniform than the mother colloid. The as-prepared Ag nanoparticulate films were shown to be active for surface-enhanced Raman scattering(SERS), as evidenced by the strongly enhanced Raman scattering from the self-assembled films(SAMs) of p-mercaptoaniline(p-MA).展开更多
The aligned array and thin film of zeolites and molecular sieves possess a variety of potential applica- tions in membrane separation and catalysis, chemical sensors, and microelectronic devices. There are two main sy...The aligned array and thin film of zeolites and molecular sieves possess a variety of potential applica- tions in membrane separation and catalysis, chemical sensors, and microelectronic devices. There are two main synthesis methods for manufacturing the aligned arrays and thin films of zeolites and mo- lecular sieves, i.e. in situ hydrothermal reaction and self-assembly of crystal grains on substrates. Both of them have attracted much attention in the scientific community worldwide. A series of significant progress has been made in recent years. By the in situ hydrothermal synthesis, the oriented nucleation and growth of zeolite and molecular sieve crystals can be achieved by modifying the surface properties of substrates or by changing the composition of synthesis solutions, leading to the formation of uni- formly oriented multicrystal-aligned arrays or thin films. On the other hand, the crystal grains of zeo- lites and molecular sieves can be assembled onto the substrate surface in required orientation using different bondages, for instance, the microstructure in the array or thin film can be controlled. This review is going to summarize and comment the significant results and progress reported recently in manufacturing highly covered and uniformly aligned arrays or thin films of zeolites and molecular sieves. It involves (1) in situ growth of highly aligned zeolite arrays and thin films via embedding func- tional groups on the substrate surface, modifying the surface microstructure of substrates, as well as varying the composition of synthesis solutions; (2) assembly of zeolite and molecular sieve crystals on various substrates to form aligned arrays and thin films with full coverage by covalent, ionic, and in- termolecular coupling interactions between crystals and substrates; (3) coupling surface assembly with microcontact printing or photoetching technique to produce patterned zeolite arrays and thin films. Finally, the functionality and applications of zeolite arrays and thin films are briefly introduced.展开更多
CdS nanocrystals, which were surface modified by poly (nickel dithioxamide) n, were prepared and characterized. TEM image showed that the shape and the outward aspect of the modified CdS sample were essentially the sa...CdS nanocrystals, which were surface modified by poly (nickel dithioxamide) n, were prepared and characterized. TEM image showed that the shape and the outward aspect of the modified CdS sample were essentially the same as those of the original material and no impurities were found. The characteristic IR peaks at 1 513 cm-1 and 870 cm-1 confirmed the success in assembling n on the surface of CdS. For XPS spectra, the characteristic bands of Ni2p3/2 and Ni2p1/2 appeared at 856 eV and 877 eV indicating the nickel in Ni(Ⅱ)oxidation state. The solid state electronic spectra showed the improvement in surface energy gap, which was changed from 2.38 eV to below 1.91 eV.展开更多
近两年来，QFN封装(Quad flat No—lead方形扁平无引脚封装)由于其良好的电和热性能，得到了快速的推广和应用。采用微型引线框架的QFN封装称为MLF封装(Micro Lead Frame——微引线框架)。全球最大微电子制造商之一的Amkor公司，已经销...近两年来，QFN封装(Quad flat No—lead方形扁平无引脚封装)由于其良好的电和热性能，得到了快速的推广和应用。采用微型引线框架的QFN封装称为MLF封装(Micro Lead Frame——微引线框架)。全球最大微电子制造商之一的Amkor公司，已经销售MLF封装的IC超过1亿只。因此人们迫切希望了解有关QFN的焊盘设计、装配工艺以及板级可靠性设计和工艺等方面的技术问题。由于QFN封装没有焊球，元件与PCB的电气连接是通过印刷焊膏到PCB上，然后贴片和进行回流焊完成的。为了形成可靠的焊点，需要特别注意焊盘的设计，同样．由于这种元件底部有大面积焊盘，其表面贴装工艺很复杂，要求进行合适的模板设计、焊膏印刷，以及回流焊曲线设置。本文对上述各方面要求和影响进行探讨，对PCB焊盘设计、表面组装工艺以及板级组装的可靠性作了详细地介绍。展开更多
文摘We present our work on direct assembly of Ag nanoparticulate film onto mica substrates without coupling agent, and investigate the potential application of this kind of assembly to SERS. Colloidal Ag is assembled onto mica substrates treated with MnCl 2 solution by electrostatic interaction, which forms a two-dimensional submonolayer. As shown by AFM study, the assembled process is size-selective, e.g., Ag particles assembled onto mica are more uniform than the mother colloid. The as-prepared Ag nanoparticulate films were shown to be active for surface-enhanced Raman scattering(SERS), as evidenced by the strongly enhanced Raman scattering from the self-assembled films(SAMs) of p-mercaptoaniline(p-MA).
基金the National Natural Science Foundation of China(Grant Nos.20476074and20636030)the Natural Science Foundation of Tianjin(Grant No.06YFJMJC04700)
文摘The aligned array and thin film of zeolites and molecular sieves possess a variety of potential applica- tions in membrane separation and catalysis, chemical sensors, and microelectronic devices. There are two main synthesis methods for manufacturing the aligned arrays and thin films of zeolites and mo- lecular sieves, i.e. in situ hydrothermal reaction and self-assembly of crystal grains on substrates. Both of them have attracted much attention in the scientific community worldwide. A series of significant progress has been made in recent years. By the in situ hydrothermal synthesis, the oriented nucleation and growth of zeolite and molecular sieve crystals can be achieved by modifying the surface properties of substrates or by changing the composition of synthesis solutions, leading to the formation of uni- formly oriented multicrystal-aligned arrays or thin films. On the other hand, the crystal grains of zeo- lites and molecular sieves can be assembled onto the substrate surface in required orientation using different bondages, for instance, the microstructure in the array or thin film can be controlled. This review is going to summarize and comment the significant results and progress reported recently in manufacturing highly covered and uniformly aligned arrays or thin films of zeolites and molecular sieves. It involves (1) in situ growth of highly aligned zeolite arrays and thin films via embedding func- tional groups on the substrate surface, modifying the surface microstructure of substrates, as well as varying the composition of synthesis solutions; (2) assembly of zeolite and molecular sieve crystals on various substrates to form aligned arrays and thin films with full coverage by covalent, ionic, and in- termolecular coupling interactions between crystals and substrates; (3) coupling surface assembly with microcontact printing or photoetching technique to produce patterned zeolite arrays and thin films. Finally, the functionality and applications of zeolite arrays and thin films are briefly introduced.
文摘CdS nanocrystals, which were surface modified by poly (nickel dithioxamide) n, were prepared and characterized. TEM image showed that the shape and the outward aspect of the modified CdS sample were essentially the same as those of the original material and no impurities were found. The characteristic IR peaks at 1 513 cm-1 and 870 cm-1 confirmed the success in assembling n on the surface of CdS. For XPS spectra, the characteristic bands of Ni2p3/2 and Ni2p1/2 appeared at 856 eV and 877 eV indicating the nickel in Ni(Ⅱ)oxidation state. The solid state electronic spectra showed the improvement in surface energy gap, which was changed from 2.38 eV to below 1.91 eV.
文摘近两年来，QFN封装(Quad flat No—lead方形扁平无引脚封装)由于其良好的电和热性能，得到了快速的推广和应用。采用微型引线框架的QFN封装称为MLF封装(Micro Lead Frame——微引线框架)。全球最大微电子制造商之一的Amkor公司，已经销售MLF封装的IC超过1亿只。因此人们迫切希望了解有关QFN的焊盘设计、装配工艺以及板级可靠性设计和工艺等方面的技术问题。由于QFN封装没有焊球，元件与PCB的电气连接是通过印刷焊膏到PCB上，然后贴片和进行回流焊完成的。为了形成可靠的焊点，需要特别注意焊盘的设计，同样．由于这种元件底部有大面积焊盘，其表面贴装工艺很复杂，要求进行合适的模板设计、焊膏印刷，以及回流焊曲线设置。本文对上述各方面要求和影响进行探讨，对PCB焊盘设计、表面组装工艺以及板级组装的可靠性作了详细地介绍。
