新型热释电材料及其在红外探测器中的应用

以(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3{PMNT[(1-x)/x}为代表的大尺寸、高质量弛豫铁电单晶具有非常高的热释电系数、探测优值和较低的热扩散系数,其综合热释电性能远优于传统的热释电材料.概述了PMNT[(1-x)/x]单晶、掺锰PMNT(74/26)单晶和0.42Pb(In1/2Nb1/2)...     

Chemical mechanical polishing of polymeric materials for MEMS applications

Polymeric materials such as polycarbonate (PC) and poly-methyl methacryate (PMMA) are replacing silicon as the major substrate in microfluidic system fabrication due to their outstanding features such as low cost and good chemical resistance. In this study, chemical mechanical polishing (CMP) of PC and PMMA substrates was investigated. Four types of slurry were tested on CMP of the polymers under the same process conditions. The slurry suitable for polishing PC and PMMA was then chosen, and further CMP experiments were carried out under different process conditions. Experimental results showed that increasing table speed or head load increased the material removal rates of the polymers. The polymeric surface quality after CMP was acceptable to most MEMS applications. Analysis of variance was also carried out, and it was found that the interaction of head load and table speed had a significant (95% confidence) effect on surface finish of polished PMMA. On the other hand, table speed had a highly significant (99% confidence) effect on surface finish of polished PC.     

Sorptive polymeric materials and photopatterned films for gas phase chemical microsensors

The selective layer on a gas phase chemical microsensor plays a critical role in the sensitivity and selectivity of the sensor's response. Polymers can rapidly and reversibly absorb vapor molecules. As sorptive layers on chemical sensors, polymers are useful for a variety of chemical microsensor types and transduction mechanisms, either as is or as composites with conductive particles or dyes. The performance requirements for polymers are described in terms of their chemical and physical properties. A versatile synthetic approach for preparing sensing polymers has been developed using hydrosilylation chemistry to prepare carbosiloxane polymers. Polymers with diverse chemical selectivities have been prepared by this method. Furthermore, sorptive polymer materials can be photopatterned into defined areas on surfaces using a photoactivated catalyst and hydrosilylation chemistry. Polymer films with diverse chemical selectivities have been patterned with this new method.     

Rheology based modeling and design of particle laden polymeric thermal interface materials

Most of the research on particle laden polymeric (PLP) thermal interface materials (TIM) have been primarily focused ob understanding the thermal conductivity of these types of TIMs. For thermal design reduction of the thermal resistance is the end goal. Thermal resistance is not only dependent on the thermal conductivity, but also on the bond line thickness (BLT) of these TIMs. This paper introduces a rheology based model for the prediction of the BLT of these TIMs from very low to very high pressures. BLT depends on the yield stress of the particle laden polymer and the applied pressure. The model is based on the concept of finite size scaling of physical properties of particle laden systems at very thin length scale due to percolation phenomenon in these materials. This paper shows that the yield stress of the PLP increases with decreasing thickness of the TIM and therefore it is size dependent. The BLT model combined with the thermal conductivity model can be used for modeling the thermal resistance of these TIMs for factors such as particle volume faction, substrate/die size, pressure and particle diameter.     

Interface microstructure effects in Au thermosonic ball bonding contacts by high reliability wire materials

Palladium-doped and (Cu, Pt)-doped high reliability gold wires were used to form wire bond interconnects on aluminum IC metallization. By isothermal annealing of wire bond samples the formation of intermetallic Au–Al phases was stimulated. SEM/EBSD investigations of the phase regions exhibited significantly slower isothermal growth rates compared to a reference gold wire. Correlated TEM, STEM–EDXS and nanobeam diffraction analyses revealed that Pd is preferentially incorporated into the Au₈Al₃ intermetallic forming a new stable phase but additionally can obviously form a new Pd-rich ternary intermetallic. In comparison, Cu dopants are also accumulated into a new Al–Au–Cu phase while Pt is rather found agglomerating within grain boundaries and interfaces. These results suggest a diffusion barrier model that allows discussing how wire doping can affect the bond contact microstructure, thus increasing the lifetime of bond contacts.     

高频高速印制板材料导热性能的研究进展

随着电子技术的发展,对高频高速印制板导热性越来越高的要求。除了开发高成本的高导热性聚合物材料外,在聚合物中填充高导热性的无机材料也是提高高频高速印制板基材导热性能的有效方法,而且填充型复合材料可以用理论模型预测其导热系数。主要综述了填料的形貌、分布与表面改性对填充型复合材料导热系数的影响等方面的研究进展。     

电子塑封材料的高温界面强度研究

为了研究最常见的电子封装失效模式之一——高温下的界面破坏机理,在传统剪切拉拔实验的基础上进行了改良,运用焊接力测试机(Dage 4000)、拉伸机、热控制仪和热烘箱等辅助仪器,实现了电子塑封材料在高温下的界面强度测试.结果表明,界面强度随着温度的升高而降低,特别是在跨越塑封材料的玻璃转换温度时,界面强度有显著降低.比较...     

Mechanical interactions and their effects on chemical mechanicalpolishing

Mechanical interactions, such as contact stress and fluid pressure are of extreme importance in silicon wafer polishing, especially for the wafer-scale planarity of the finished surfaces. In this paper, the measurements of interfacial fluid pressure and friction, as well as their dependence on some major process variables, are presented. A nonuniform subambient fluid pressure was measured, and the resulting wafer/pad contact stress, obtained by combining the effects of both applied normal load and interfacial fluid pressure, is determined. An analytical model was developed to predict the magnitude and distribution of the interfacial fluid pressure. The results of polishing experiments show good evidence of the effects of this subambient fluid pressure on with in-wafer nonuniformity (WIWNU). By properly designing the polishing process variables, the fluid pressure may be tailored, and a relatively uniform material removal can be achieved     

络合剂对NASICON材料的影响

摘要:采用以无机盐为基础的新型溶胶-凝胶法合成了固体电解质NASICON材料。合成过程中,通过向原溶液中添加草酸作络合剂,有效降低了烧结温度,缩短了烧结时间。实验中,利用XRD、TEM等分析测试手段对草酸络合剂以及合成产物的影响情况进行了对比研究,对络合剂的作用机理进行了讨论。     

Curing shrinkage effects of UV-curable materials on fiber losscharacteristics

The curing shrinkage effect in the radial direction of ultraviolet UV-curable coating on fiber-loss characteristics is investigated theoretically and experimentally. It is shown that curing shrinkage causes lateral forces to the fiber and leads to microbending loss increases at low temperatures. A model for pressure caused by curing shrinkage in the radial direction is discussed. According to this model, the radial pressure to the optical fiber in the coating can be estimated by measuring the fiber pulling force from the coated optical fiber. Based on the agreement of theoretical and experimental results, the allowable range of curing shrinkage percentages of primary and secondary coatings to prevent fiber-loss increase is obtained. Design strategies to prevent fiber loss increases at low temperatures are described     

Chalcogenide materials and their application to Non-Volatile Memories

Chalcogenide materials are chemical compounds consisting of at least one chalcogen ion, i.e. a chemical element in column VI of the periodic table also known as the oxygen family. More precisely the term chalcogenide refers to the sulphides, selenides, and tellurides. Among the various applications of this class of materials, we review here two types of Non-Volatile Memories (NVM): the Phase Change Memories (PCM) which rely on the rapid crystallisation and high electrical contrast between the amorphous and crystalline phases of some of these compounds, and the Current Bridging Random Access Memories (CBRAM) which make use of the ionic conduction of compounds containing metallic ions.     

Window materials for high power gyrotron

The room temperature application of sapphire as window material at higher frequencies is not feasible since its absorption coefficient increases almost linearly with increasing frequency in the millimeter wavelength region. At cryogenic temperature the absorption coefficient value decreases only by a few factors (factor of 2 to 3) in the 90 – 200 GHz region. The earlier reported temperature squared dependence (decrease) in the absorption coefficient or the loss tangent value is totally absent in our broad band continuous wave data we are reporting here (at 6.5 K, 35K, 77K and 300K) and one we reported at conferences earlier. Our results are verified by another technique. We utilize our precision millimeter wave dispersive Fourier transform spectroscopic techniques at room temperature and at cryogenic temperatures The extra high resistivity single crystal compensated silicon is no doubt the lowest loss material available at room temperature in the entire millimeter wavelength region At higher millimeter wave frequencies an extra high resistivity silicon window or an window made with extra high resistivity silicon coated with diamond film would certainly make a better candidate in the future. A single free standing synthetic diamond window seems to have higher absorption coefficient values at millimeter wavelength region at this time although it is claimed that it possesses good mechanical strength and higher thermal conductivity characteristics. It certainly does not rule out the use of diamond film on a single crystal high resistivity silicon to improve its mechanical strength and thermal conductivity     

含能材料激光点火的氧平衡问题研究

实验研究了含能材料激光点火的氧平衡问题。对Zr/KClO4 等的临界激光点火能量的测定实验表明,锆与高氯酸钾的质量比对Zr/KClO4 的临界激光点火能量阈值有明显影响,在其他条件、因素相同的情况下,当偏富氧配比时,有利于激光点火,即点火的阈值能量低,或者说含能材料的激光感度较高。     

Analysis of composite walls and their effects on short-pathpropagation modeling

For short-propagation paths, correctly representing reflections of electromagnetic energy from surfaces is critical for accurate signal-level predictions. In this paper, the method of homogenization is used to determine the effective material properties of composite materials commonly used in construction. The reflection coefficients for block walls and other types of materials calculated with these homogenized effective material properties are presented. The importance of accurately representing the reflections for signal-level prediction models is also investigated. It is shown that a 5-10-dB error in received signal strength (RSS) can occur if the composite walls are not handled appropriately. Such accurate predictions of signal propagation over a short distance is applicable to microcellular personal communications services deployments in urban canyons as well as indoor wireless private branch exchanges and local-area networks     

TFT LCD中常用的材料及其工作原理

TFT LCD是平板显示器的一种。本文介绍了TFT LCD常用的材料及其工作原理。     

驻极体声传感器及其储电材料的现状

综述了驻极体声传感器及其储电材料近年来的迅猛发展。传统的FEP(tetrafluoroethylene—hexa—fluoropropylene copolymer)极体电容式声传感器及以铁电聚合物PVDF(poly vinylidene fluoride)家族为芯片的声传感器和超声抉能器仍焕发着青春活力。Si基微型驻极体声传感器的理论和实验研究已经日趋成熟,而用空间电荷型多孔聚合物驻极体压电薄膜为芯片可望研制出新一代声电和电声传感器、压力传感器和驱动器。     

高介高稳定性BaTiO3基铁电陶瓷研究进展

针对BaTiO3基铁电陶瓷材料的特点,介绍了提高其介电常数和温度稳定性的途径,综述了高介高稳定性BaTiO3基铁电陶瓷材料的研究现状。指出随着电子整机向着微型化的方向发展,介电瓷粉材料也向着高介电常数、高稳定性的方向发展,并提出了解决此问题的思路。     

High field-effect-mobility a-Si:H TFT based on high deposition-ratePECVD materials

The hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFT's) having a field-effect mobility of 1.45 ±0.05 cm² /V·s and threshold voltage of 2.0±0.2 V have been fabricated from the high deposition-rate plasma-enhanced chemical vapor deposited (PECVD) materials. For this TFT, the deposition rates of a-Si:H and N-rich hydrogenated amorphous silicon nitride (a-SiN_1.5 :H) are about 50 and 190 nm/min, respectively. The TFT has a very high ON/OFF-current ratio (of more than 10⁷), sharp subthreshold slope (0.3±0.03 V/decade), and very low source-drain current activation energy (50±5 meV). All these parameters are consistent with a high mobility value obtained for our a-Si:H TFT structures. To our best knowledge, this is the highest field-effect mobility ever reported for an a-Si:H TFT fabricated from high deposition-rate PECVD materials