LTCC基板制造工艺研究

低温共烧多层陶瓷（ＬＴＣＣ）基板是制造复杂微电子产品多芯片组件（ＭＣＭ）的重要部件。详细地讨论了ＬＴＣＣ基板制造工艺，介绍了多年研究之经验及国外的有关技术，还指出了目前工艺中存在的技术问题及在工艺水平上与国外的差距。采用目前工艺，可做出２０层布线、线宽及间距均为０．２０ｍｍ、８０ｍｍ×８０ｍｍ的多层共烧基板     

在金属基片上以LNO为过渡层制备Pb(Zr0.53Ti0.47)O3薄膜的电性能

采用溶胶-凝胶法和快速热处理工艺,分别以不锈钢(SS)和镍合金(NC)为基片,成功制备了表面均匀、无裂纹的锆钛酸铅(Pb(Zn0.53Ti0.47)O3,简写为PZT)薄膜.为了缓解金属基片与PZT薄膜之间由于晶格常数和热膨胀系数不同所造成的不匹配状态,引入了镍酸镧(LaNiO3,简写为LNO)薄膜作为过渡层.XRD和SEM结果表明,经过600℃下30min的晶化,PZT薄膜已经由无定型转化为钙钛矿相.以LNO为过渡层,在NC金属基片上制备的PZT薄膜具有较高的介电常数和较低的损耗(1kHz下ε=717,tanδ=0.08),较低的漏电流(50kV/cm下J=2.6×10-7A/cm2)以及较好的铁电性能(+Pr=90μC/cm2,-Pr=14 μC/cm2,Ec=32.5kV/cm).同时,在SS基片上,通过引入LNO过渡层,制备的PZT薄膜也具有比较好的性能.     

Mapping the Neural Substrates Involved in Maternal Responsiveness and Lamb Olfactory Memory in Parturient Ewes Using Fos Imaging.

In sheep, recognition of the familiar lamb by the mother depends on the learning of its olfactory signature after parturition. The authors quantified Fos changes in order to identify brain regions activated during lamb odor memory formation. Brain activation was compared with those measured in anosmic ewes displaying maternal behavior but not individual lamb recognition. In intact ewes, parturition induced significant increase in Fos expression in olfactory cortical regions and in cortical amygdala, whereas in anosmic mothers, Fos expression was very low. In contrast, no difference was observed between intact and anosmic ewes in hypothalamic areas and medial amygdala, suggesting a differentiation between the neural network controlling maternal responsiveness and that involved in olfactory lamb memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible rewritable organic memory devices using nitrogen-doped CNTs/PEDOT:PSS composites

Nonvolatile rewritable organic memory devices based on poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and nitrogen doped multi-walled carbon nanotube (NCNT) nanocomposites were fabricated on glass and PET substrates.Organic memory devices with bistable resistive switching were obtained using very low NCTN concentration (∼0.002 wt%) in the polymeric matrix. The memory devices exhibited a good ON/OFF ratio of approximately three orders of magnitude, a good retention time of 10⁴ s under operating voltages ≤ |4V| and a few hundredths of write-read-erase-read cycles. The bistable resistive switching is mainly attributed to the creation of oxygen vacancies. These defects are introduced into the thin native Al oxide (AlOx) layer on the bottom electrode during the first voltage sweep. The well-dispersed NCNTs immersed in PEDOT:PSS play a key role as conductive channels for the electronic transport, hindering the electron trapping at the AlOx-polymer interface and inducing a soft dielectric breakdown of the AlOx layer. These PEDOT:PSS + NCNTs memory devices are to easy to apply in flexible low-cost technology and provide the possibility of large-scale integration.     

DMAB显现纸张表面潜在手印应用研究

纸张类客体是案件现场中常见的一类检材,其表面潜在手印的显现在物证检验鉴定过程中具有重要的意义。利用氨基酸敏感试剂N,N-二甲基-4-氨基苯甲醛(DMAB)对纸张表面潜在手印进行显现研究,结果表明,当浓度为0.4%时,DMAB对纸张表面潜在手印有很好的显现效果,显现手印在490 nm光源照射时,橙色护目镜下可观察到黄色荧光。该方法显现灵敏度高、显出手印纹线清晰、与背景反差较大,对于遗留30 d的陈旧性手印仍具有良好的显现效果。     

Colorless polyimides with low coefficient of thermal expansion derived from alkyl‐substituted cyclobutanetetracarboxylic dianhydrides

Alkyl‐substituted cyclobutanetetracarboxylic dianhydrides (CBDAs) were synthesized by photo‐dimerization of alkyl‐substituted maleic anhydrides to obtain novel colorless polyimides (PIs). Dimethyl‐substituted CBDA (DM‐CBDA) showed much higher polymerizability with various diamines than conventional cycloaliphatic tetracarboxylic dianhydrides and led to high molecular weights of PI precursors. Polyaddition of non‐substituted CBDA and trans‐1,4‐cyclohexanediamine (t‐CHDA) was completely inhibited by salt formation in the initial reaction stage. The use of DM‐CBDA allowed the formation of a homogeneous/viscous PI precursor solution by overcoming the salt formation problem. The prominent substituent effect probably reflects how the methyl substituents of DM‐CBDA contributed to increasing the salt solubility. Some of the thermally imidized DM‐CBDA‐based systems simultaneously possessed non‐coloration, low coefficient of thermal expansion (CTE), very high T_g exceeding 300 °C and very low dielectric constant. Copolymerization was very effective for improving the solubility of DM‐CBDA‐based PIs. The copolyimide cast films prepared via chemical imidization displayed a further decreased CTE without sacrificing other target properties, suggesting that the present materials can be useful as plastic substrates in display devices. The mechanism of self‐chain orientation behavior during solution casting is also discussed. A potential application of the copolyimide systems as optical compensation film materials in liquid crystal displays is proposed. © 2013 Society of Chemical Industry .     

Reduced water vapor transmission rates of low-temperature-processed and sol-gel-derived titanium oxide thin films on flexible substrates

Sol-gel-derived, crack-free, and condensed TiO_x thin films with improved barrier properties were successfully fabricated on polymeric substrates with a simple two-step heat treatment at low temperatures. To assess the barrier properties of the TiO_x thin films, Ca corrosion tests were conducted and their water vapor transmission rates (WVTRs) were measured. We found that the two-step heat treatment (at 45 °C for 90 min and 110 °C for 60 min) produces a close-packed TiO_x structure that substantially reduces the WVTRs of the coated polymeric substrates. The WVTRs of 86 nm thick TiOx thin films on polyethylene naphthalate (PEN) substrates at a relative humidity (RH) of 90% were found to be 0.133 g m⁻² day⁻¹ at 38 °C and 0.0387 g m⁻² day⁻¹ at 25 °C. In addition, the WVTR value of the TiO_x thin films on PEN substrates are stable with respect to bending: it was found to increase by only ∼13% after 100 repetitions of bending with a 20 mm radius.     

Direct shaping of oxides by laser insolation of transition metal oxalates

Films of copper and cobalt-iron oxalates were prepared from suspensions of powders in ethane-1,2-diol deposited on glass or polycarbonate substrates. Two-dimensional structures of oxides, resolved on the scale of less than ten micrometers, were formed by laser insolation of these films, using a photolithography machine. The nature of the constitutive phases of the oxides formed tends to show that the laser heating makes it possible to reach locally, temperatures higher than 1000 °C. The oxides formed are thus sintered. The residual oxalate can be removed by washing or dissolving, leaving the oxide structure on its substrate. In spite of a perfectible sintering, the formed structures could interest different technological applications (electronic or magnetic devices, gas sensors, photovoltaic systems…) requiring the shaping of simple or mixed oxides on a scale close to the micrometer. The process of selective laser decomposition of oxalates, could subsequently be suitable for additive manufacturing of 3D parts.     

Chemical vapor deposition of boron- and nitrogen-containing graphene thin films

Boron and nitrogen-incorporated graphene thin films were grown on polycrystalline Ni substrates by thermal chemical vapor deposition using separate boron- and nitrogen-containing feedstocks. Boron and nitrogen atoms were incorporated in the film in almost equal amounts and the total content reached ∼28%. The film predominantly consisted of separate graphene and boron nitride domains. Carrier concentration in the graphene domains was estimated to be about 1 × 10⁻³ e/atom (3.8 × 10¹² cm⁻²) from G band shift in Raman spectra.