Shielding effectiveness of single and double plates with slits

Transverse electric (TE) wave transmission through slits on single and double metal plates of finite thickness is studied by using Galerkin's method. It is observed that by either using a thick plate (for slit narrower than half a wavelength) or using double plates with slits laterally shifted (for slits wider than half a wavelength), the amount of power transmitted through the slits can be significantly reduced. These schemes can be applied to improve the shielding effectiveness of equipment cabinets     

单层和多层有缝金属板电磁波透射的FDTD分析

采用在入射波一侧的总场边界处同时引进入射波和反射波作为激励源的FDTD方法来分析斜入射时单层和多层有缝金属板电磁波透射问题.通过计算金属板缝隙附近的散射场,提取缝隙口径面上的等效面磁流,进而得到透射截面.计算机仿真结果证实了算法的有效性.数值计算结果表明,两金属板上所开缝隙的相对偏移以及两板间插入介质板将会改变屏蔽效应.该方法可以有效分析平面波斜入射时多层金属板上任意形状缝隙的散射和透射,包括缝隙内或金属板之间填充有介质情形.     

Intrinsic and extrinsic reliability of a serial connection of capacitors

The on-wafer serial connection of two capacitors (stacked capacitors) is attractive for two reasons: on one hand the intrinsic reliability and especially the immunity against high voltage pulses increases and on the other hand the early fail risk decreases tremendously. The intrinsic and extrinsic reliability of stacked capacitors are demonstrated using the example of a metal insulator metal capacitor (MIMCAP) with Al₂O₃ dielectric. The intrinsic reliability of a stacked capacitor, where each of the capacitors uses a dielectric of thickness thk, is equal to the intrinsic reliability of a single capacitor with twice the dielectric thickness 2 * thk. The reduction of early fails for a stacked capacitor is a probability effect: if a single capacitor has the probability p to fail early and an early fail of the stacked capacitor is the combination of two single capacitors each of which contains an early fail, then the stacked capacitor fails early with a probability of p². This basic idea is checked by voltage ramp experiments on single and stacked MIM capacitors, where the single MIM capacitors show besides the intrinsic branch a prominent extrinsic branch.     

基于H形金属狭缝阵列结构双共振谷折射率传感特性

提出了一种基于H形金属狭缝阵列的新型结构。利用该结构形成的法布里-珀罗腔(Fabry-Perot,F-P)来加强表面等离激元的耦合作用,以获得一种双共振反射现象;同时研究了基于该现象的折射率传感特性。采用时域有限差分法研究了该结构中狭缝长度、宽度、金膜厚度等参数对双共振反射现象的影响。研究发现,双共振谷波长可由以上主要参数有效调控,当竖直狭缝长度为150nm、水平狭缝长度为200nm、狭缝宽度为50nm、金膜厚度为300nm时,该结构具有较好的双共振反射现象,其灵敏度分别为590和1199nm/RIU。该发现为新一代高性能表面等离子共振传感器设计提供了理论参考。     

Investigations into Operation of Single- and Multi-Layer Configurations of Planar Inverted-F Antenna

The paper presents a tradeoff analysis between single- and multi-layer (stacked) configurations of a planar inverted-F antenna (PFIA) of fixed overall height, with respect to achieving multi-band operation. The investigations focus on two bands, 800 to 1000 MHz and 1700 to 2600 MHz, which cover a frequency spectrum allocated to most of the present-day wireless systems operating below 2600 MHz. Folding and tapering of a conducting patch in the single-layer configuration, and increasing the number of conducting patches in the multi-layer layer (stacked) configuration, are used to achieve multi-band operation. The results obtained show that the stacked PIFA is able to generate many (four or more) bands within the investigated frequency spectrum. However, it faces difficulty in broadening them, as the coupling of upper plates to the ground is weakened by the presence of middle plates. At the same time, the tuning of one band adversely affects the other bands' performance. For the single-layer PIFA, the multi-band impedance characteristics are easier to adjust. A significant band widening can be obtained by proper arrangement of a conducting patch, and by introducing cuts or slits in the ground plane. In the designs presented, the antenna volume, measured by its outline, fell under 3 cm³. The resulting radiation efficiencies were 95% at the lower band (900 MHz), and 89% at the upper frequency range (2020 MHz).     

Propagation of ultrawideband chaotic radio pulses through the slits of metal surfaces

The leakage of ultrawideband (UWB) chaotic radio pulses through the defects (holes, slits, cracks, etc.) of metal surfaces-an urgent problem arising from their application as information carriers in wireless sensor networks-is investigated. Experiments with UWB chaotic radio pulses leaking from the slits of metal surfaces are described, and the experimental results are analyzed. The signal attenuation has been estimated when chaotic radio signals propagate through slits of different size.     

Single Slab Arbitrary Polarization Surface Wave Structure

A single grounded dielectric slab can support either TM or TE modes, but cannot propagate both with the same velocity. This paper concerns a modification of the single slab which enables either polarization to propagate with the same velocity. Such a structure could transmit a circularly polarized wave, and would be useful in transmission, feeder, and antenna applications. The structure consists of a grounded dielectric slab with parallel metal plates imbedded in the dielectric, normal to and in contact with the ground plane. The plates do not reach the top of the slab. Propagation is along the plates, whereas corrugated surfaces propagate across the vanes. For small plate thickness, the TE field is undisturbed; hence, the entire slab thickness controls the velocity. The TM field, however, has an electric field component parallel to the plates, which is shorted out by the plates; thus, only the thickness of slab above the plates controls this mode, and the two modes can be independently controlled.     

多层芯片应用中的封装挑战和解决方案

The continuous growth of stacked die packages is resulting from the technology‘s ability to effectively increase the functionality and capacity of electronic devices within the same footprint as a single chip.The increased utilization of stacked die packages in cell phone and other consumer products drives technologies that enable multiple die stacks within a given package dimension.This paper reviews t6he technology requirements and challenges for stacked die packages.Foremost among these is meeting package height is 1.2mm for a single die package.For stacked die packages,two or more die need to fit in the same area.That means every dimension in the package has to decrease,including the die thickness.the mold cap thickness,the bond line thickness and the wire bond loop profile.The technology enablers for stacked die packages include wafer thinning,thin die attachment,low profile wire bonding,bonding to unsupported edges and low sweep molding.     

A Circularly Polarized Stacked Patch Aperture Coupled Microstrip Antenna for 2.6 GHz Band

A circularly polarized stacked patch microstrip antenna and a 2?×?2 subarray for circular polarization are proposed in this paper. The proposed design has the input impedance bandwidth and axial ratio bandwidth of about 10% and 4.7% respectively. Circular polarization is obtained with the help of slits cut in the patch. A size reduction of around 37% is also achieved with the help of the slits. A subarray based on sequentially rotated feeding technique for circular polarization is also presented in this paper. Array element was deigned using a high dielectric constant laminate for feed network. In addition to low boresight axial-ratio, the subarray has impedance and 3-dB axial-ratio bandwidths of 12% and 8% respectively.     

Guanine‐Based Biogenic Photonic‐Crystal Arrays in Fish and Spiders

Biological photonic systems composed of anhydrous guanine crystals evolved separately in several taxonomic groups. Here, two such systems found in fish and spiders, both of which make use of anhydrous guanine crystal plates to produce structural colors, are examined. Measurements of the photonic‐crystal structures using cryo‐SEM show that the crystal plates in both fish skin and spider integument are ～20‐nm thick. The reflective unit in the fish comprises stacks of single plates alternating with ～230‐nm‐thick cytoplasm layers. In the spiders the plates are formed as doublet crystals, cemented by 30‐nm layers of amorphous guanine, and are stacked with ～200 nm of cytoplasm between crystal doublets. They achieve light reflective properties through the control of crystal morphology and stack dimensions, reaching similar efficiencies of light reflectivity in both fish skin and spider integument. The structure of guanine plates in spiders are compared with the more common situation in which guanine occurs in the form of relatively unorganized prismatic crystals, yielding a matt white coloration.     

一种新型金属透镜天线设计

为了获得具有高增益特性的天线，对传统透镜天线工作原理进行了分析。因为透镜天线板间电场模式与波导中电场模式类似，以此为依据通过改变金属透镜的金属平板间距和板脊高度，设计了一种新型金属透镜天线，迥异于传统金属透镜天线的凹形曲面结构。该天线金属透镜由多片长方形侧面加脊金属板组成，能够很好地调节口径面的相位分布，以此实现口径面同相分布，从而获得高增益性能。     

Reflectors for a Microwave Fabry-Perot Interferometer

The advantages of microwave interferometers for wavelength and other measurements at millimeter wavelengths are indicated, and a microwave Fabry-Perot interferometer discussed in detail. Analogous to the cavity resonator, this requires reflectors of high reflectivity, small absorption, and adequate size. Stacked dielectric plates, and stacked planar or rod gratings are shown to be suitable forms of reflectors, and equations for the reflectivity, optimum spacing, and bandwidth of such structures are derived. A series of stacked metal plates with regularly spaced holes represents a good design of reflector for very small wavelengths. Fringes and wave-length measurements at 8-mm wavelength are given for one design of interferometer, these being accurate to 1 in 10/sup 4/ without any diffraction correction. For larger apertures and reflectors in terms of the wavelength, errors due to diffraction will decrease.     

Closed-form low frequency solutions for electromagnetic waves through a frequency selective surface

A simple closed-form approximate solution is given to the problem of transmission of a low-frequency electromagnetic wave through a frequency selective surface (FSS). FSS are periodic metal plates (or their complimentary apertures) sandwiched between dielectric slabs. At low frequencies, the induced currents on the metal plates may be approximated by a known function with a constant coefficient to be determined by the boundary conditions. Based on such a "one-mode" approximation, we derive a closed-form solution for the scattered field for FSS with multiple narrow rectangular slots, with a single wide rectangular aperture, and a circular aperture. When compared with the available exact solutions, we find that the one-mode approximation is valid when the periodaof the FSS is such thata/lambdais small enough that no grating lobe appears, e.g.,a < lambdafor normal incidence.     

叠层芯片封装技术与工艺探讨

论述了在叠层芯片封装的市场需求和挑战。首先采用在LQFP一个标准封装尺寸内,贴装2个或更多的芯片,这就要求封装体内每一个部分的尺寸都需要减小,例如芯片厚度、银胶厚度,金丝弧度,塑封体厚度等,要求在叠层封装过程中开发相应的技术来解决上述问题。重点就芯片减薄,银胶控制,无损化装片,立体键合,可靠性等进行了详细的介绍。     

Error analysis of polyamide plate thickness detection based on Terahertz Time Domain System

The analysis on the thickness of polyamide plate using Terahertz Time Domain System (THz-TDS) in reflection mode is carried out. The refractive index, one of the optical parameters in terahertz band, is solved through the mathematics model, and its value is 1.88. A kind of polyamide plate sample with four kinds of thickness is designed and the ability of THz-based method to detect defects or foreign bodies in fiber glass is verified by attaching metal plates to the back of fiberglass. By the comparison of traditional method and THz method, the terahertz method has a measurement error between 2.5% and 10%. As the thickness increases, the error tends to increase. The reason about the deviations is analyzed, as well as the systematic factors affecting the thickness measurement accuracy, in order to improve the accuracy of THz thickness measurement system and provide theoretical basis for designing terahertz thickness measurement system in the future.     

Physical and electrical characteristics of HfN gate electrode for advanced MOS devices

In this letter, the physical and electrical properties of physical vapor deposited (PVD) hafnium nitride (HfN) is studied for the first time as the metal gate electrode for advanced MOS devices applications. It is found that HfN possesses a midgap work function in tantalum nitride (TaN)/HfN/SiO/sub 2//Si MOS structures. TaN/HfN stacked metal-gated MOS capacitors exhibit negligible variations on equivalent oxide thickness (EOT), leakage current, and work function upon high-temperature treatments (up to 1000 /spl deg/C), demonstrating the excellent thermal stability of HfN metal gate on SiO/sub 2/. Our results suggest that HfN metal electrode is an ideal candidate for the fully depleted SOI and/or symmetric double gate MOS devices application.     

Inset microstripline-fed circularly polarized microstrip antennas

Circular polarization (CP) designs of inset microstripline-fed microstrip antennas are proposed. Three designs with a single slit, two pairs of slits, and three pairs of slits are experimentally studied. Good CP performances of the proposed antennas are achieved. For the design with three pairs of slits studied here, the center CP frequency is also seen to be lowered by about 33% compared to the case without slits, which suggests that an antenna size reduction as large as 55% can be obtained if the proposed design is used in place of a conventional CP design at a fixed frequency.     

The structural composite effect of Au–WO3–Al interconnecting electrode on performance of each unit in stacked OLEDs

In this article, we report the effects of the thickness of metal and oxide layers of the Al/WO₃/Au interconnecting structure on the electrical and optical characteristics of the upper and bottom units of the two-unit stacked organic-light-emitting-devices (OLEDs). It is found that light emission performance of the upper unit is sensitive to the transmittance of semitransparent Al/WO₃/Au structure, which can be improved by changing the thickness of each layer of the Al/WO₃/Au structure. It is important to note that the introduction of WO₃ between Al and Au significantly enhances the current efficiency of both the upper and bottom units with respect to that of the corresponding Al/Au structure without WO₃. In addition, the emission spectra of both the upper and bottom units are narrower than that of the control device due to microcavity effect. Our results indicate that the Al/WO₃/Au interconnecting structure is a good candidate for fabricating independently controllable high efficiency stacked OLEDs.