成功贴装细小片状元件的关键因素

随着主动元器件的尺寸变得越来越小，被动元件的尺寸也在减小，设计人员能够灵活的利用它们来完成高密度产品的设计。0603和0402元件的广泛使用已有多年，这些元件能够在批量应用中有很高的装配良率。最近，0201／01005元件已经进行系统装配（SiP），在手机、数码像机、无线蓝牙等产品中得以应用。0201元件约为0402元件尺寸的四分之一，而01005元件则约为0201元件尺寸的四分之一。较小尺寸的元件可能会降低装配工艺的稳健性。这类细小元件的装配比其它元件在工艺材料的选择、设计、工艺的控制方面更具敏感性。由于本身的尺寸非常小，它的尺寸公差对装配工艺也会产生非常显著的影响。所以，细小元件的装配工艺不同于其它元件，需要更加精确的控制。 本文我们讨论的是细小元件的贴片控制工艺。环球仪器SMT工艺实验室已开发完整的0201／01005元件装配工艺，如果读者对锡膏的选择、印刷工艺的控制、印刷钢网和PCB的设计、以及回流焊接工艺的控制感兴趣，欢迎和我们联系。[编者按]     

成功贴装细小片状元件的关键因素

随着主动元器件的尺寸变得越来越小，被动元件的尺寸也在减小，设计人员能够灵活的利用它们来完成高密度产品的设计。0603和0402元件的广泛使用已有多年，这些元件能够在批量应用中有很高的装配良率。最近，0201／01005元件已经进行系统装配（SiP），在手机、数码像机、无线蓝牙等产品中得以应用。0201元件约为0402元件尺寸的四分之一．而01005元件则约为0201元件尺寸的四分之一。较小尺寸的元件可能会降低装配工艺的稳健性。这类细小元件的装配比其它元件在工艺材料的选择、设计、工艺的控制方面更具敏感性。由于本身的尺寸非常小，它的尺寸公差对装配工艺也会产生非常显著的影响。所以，细小元件的装配工艺不同于其它元件，需要更加精确的控制。本文我们讨论的是细小元件的贴片控制工艺。环球仪器SMT工艺实验室已开发完整的0201／01005元件装配工艺，如果读者对锡膏的选择、印刷工艺的控制、印刷钢网和PCB的设计、以及回流焊接工艺的控制感兴趣，欢迎和我们联系。     

分级分段金手指精度控制方法

分析了选择湿膜制作分级分段金手指的精度控制主要因素，通过对工艺参数、菲林尺寸补偿控制及对位精度的研究，建立了工艺规范和控制计划，提高了分级分段金手指尺寸精度。     

自对准硅化物工艺研究

对适用于深亚微米CMOS器件的各种自对准硅化物工艺进行了讨论，并对不同硅化物薄膜的特性进行了分析。结果表明，随着大规模集成电路特征尺寸的不断缩减及其对器件性能要求的不断提高，常规Ti和Co的自对准硅化物工艺已经不能满足器件特征尺寸进一步缩小的需要；Ni的自对准硅化物工艺可以很好地满足超深亚微米及纳米器件对硅化物的需求。     

大型人字齿零件工艺路线研究

大型人字齿零件工艺难点在于既要保证尺寸精度又要保证动平衡精度，基本尺寸精度中齿部精度、基准精度以及相关同轴度不易保证，动平衡精度难以保证在于动不平衡量要求值小而去重位置回转半径大，折算成平衡质量非常小。合理的工艺路线是零线尺寸和动平衡精度保证的前提。经过几轮加工试验，不断优化工艺路线。     

以激光热解大量制作纳米尺寸的粉末

以激光热解大量制作纳米尺寸的粉末麻省理工学院研究人员于１９８１年就提出用激光感生工艺制作纳米尺寸粉末的建议，但直至现在，这种工艺还只是用于实验室规模甚少量粉末的制作。最近，意大利结构工程学会已发展一种能以低成本生产几公斤纳米尺寸粉末的激光热解工艺。该...     

Mo/Al/Mo结构电极的坡度角和关键尺寸差研究

Mo/Al/Mo结构金属作为TFT的电极,刻蚀后的坡度角和关键尺寸差是重要的参数。明确影响坡度角和关键尺寸差的工艺参数,进而控制坡度角和关键尺寸差,这对工艺制程至关重要。本文探究了膜层结构、曝光工艺、刻蚀工艺对坡度角和关键尺寸差的影响,并对刻蚀工艺进行正交试验设计。实验结果表明:Al膜厚每减小60nm,坡度角下降约9°,关键尺寸差增加0.1μm。曝光工艺中,显影后烘烤会增加光阻粘附力,导致关键尺寸差减小0.1μm,同时坡度角增加约9°。刻蚀工艺中,过刻量每增加10%,坡度角下降3.3°,关键尺寸差增加0.14μm;正交试验结果表明,对关键尺寸差、刻蚀均一性、坡度角影响因素的重要性顺序是:液刀流量Air Plasma电压水刀流量。经上述探究表明,坡度角和关键尺寸差呈负相关关系,刻蚀程度增加,关键尺寸差增加,而坡度角则减小。可以通过调节工艺参数对坡度角和关键尺寸差进行控制。     

带状光纤概述

本文首先讨论了带状光纤的工艺特点，然后重点介绍对带状光纤的几何尺寸，机械性能及环境性能的要求。     

工序尺寸图解跟踪法的计算机解算

工序尺寸链计算是机械加工工艺设计中必不可少的环节.当工件形状重杂,工艺基准多项转换工艺尺寸链环数较多时,工序间尺寸链的换算十分繁琐.文中讨论了应用图解跟踪法建立工艺尺寸链的数学解算模型,并利用VISUALFOXPRO编制工艺尺寸链图解跟踪应用程序,简化相关工序尺寸及其公差的计算.     

微机械轮式陀螺仪的结构分析

以轮式陀螺仪为研究对象，利用有限元方法分析了主要结构尺寸对其固有频率的影响。根据驱动模态和敏感模态的频率匹配，优化了陀螺的结构尺寸；通过谐响应分析确定了频率和振幅的关系，为结构设计和制备工艺提供了理论指导。     

On Undulator Radiation in Infrared and Millimeter Wave Ranges: Part 1—Classical Description

In this paper the results of theoretical and experimental research of the motion and radiation of low-voltage electron beams in Motz undulator are given. Constant magnetic field of undulator ordinary magnet under some conditions can be substituted for field of magnet dipole. Such substitution allows us to accurately integrate the electron trajectory. We can with the high accuracy consider this field as chaotic and this fact allow us to use well-known Ginsburg theory for estimation of power of braking radiation. There are longitudinal and transversal components of magnetic fields of described structure. The longitudinal component can be gained by covering of external longitudinal constant magnetic field. In this connection certain resonance effects are observed.     

Osteoclast differentiation at growth plate cartilage-trabecular bone junction in newborn rat femur

Using 3-day-old newborn rats, we examined the differentiation processes of osteoclasts associated with the destruction of the femoral growth plate cartilage and primary trabecular bone. In the growth plate cartilage, thin mineralized areas were detected solely in the longitudinal septal cartilage matrix in the hypertrophic zone, but the transverse septal cartilage matrix between adjacent chondrocytic lacunae within a row of chondrocytes remained unmineralized. The longitudinal septal cartilage between adjacent rows of chondrocytes appeared to persist, forming the walls of opened lacunar canals. Consistent with the removal of the transverse septal cartilage matrix, the longitudinal canals of opened chondrocytic lacunae were deeply invaded by capillary vessels, mononuclear cells and multinucleated pre-osteoclasts lacking a ruffled border. CD34-positive endothelial cells of capillary vessels deeply penetrated into the transverse septal cartilage matrix facing the medullary cavity and the opened chondrocytic lacunae. ED1-positive monocytes/macrophages were distributed at the chondro-osseous junction, but they were distant from the erosive front of the transverse septa. Tartrate-resistant acid phosphatase-positive multinucleated pre-osteoclasts lacking a ruffled border and differentiated osteoclasts with a ruffled border were localized mainly at two locations: the chondro-osseous junction and the growth front of primary bone trabeculae. Osteoclasts were located on the type-I collagen-positive bone trabeculae close to the growth plate, but they appeared to be distant from the type-II collagen-positive cartilage matrix. Even within opened chondrocytic lacunae, when osteoclasts were distant from the cartilage and bone matrix, they lacked polarized cytoplasmic organization and a ruffled border. The osteoclasts located in the remaining septal cartilage also exhibited neither a ruffled border nor a clear zone. Osteoclasts with a prominent ruffled border and clear zone were located in bone matrix covering the remaining septal cartilage. These results suggest that osteoclasts require hydroxyapatite crystals and bone matrix constituents for ruffled border formation and are not involved in resorption of the unmineralized transverse and mineralized longitudinal septal cartilage without covering bone matrix at the chondro-osseous junction.     

抑制冠状动脉内超声图像序列运动伪影的离线门控方法

针对连续回撤导管采集的、覆盖多个心动周期的冠状动脉内超声(ICUS)图像序列中存在的运动伪影问题,采用图像分析技术,对ICUS图像序列进行离线门控,从而改善ICUS纵向视图的视觉效果。首先,通过逐帧比较ICUS图像的灰度特征,构造ICUS序列的差异矩阵;然后,从差异矩阵中搜索出具有最小累计差异值的路径,为各帧找到其在相邻心动周期中的对应帧;最后,在滤波后的差异矩阵中,沿最优路径找到表示在各相邻心动周期舒张末期采集的图像对的点,得到最终的门控序列。对临床采集ICUS序列的实验验证了方法的可行性和精度。     

Hough transform detection of the longitudinal fissure in tomographic head images

A technique is presented for automatic detection of the longitudinal fissure in tomographic scans of the brain. The technique utilizes the planar nature of the fissure and is a three-dimensional variant of the Hough transform principle. Algorithmic and computational aspects of the technique are discussed. Results and performance on coronal and transaxial magnetic resonance data show that the algorithm is robust with respect to variations in image contrast in the data and to slight anatomic anomalies. A crucial resolution requirement in the data for accurate parameter estimations is a sufficient number of slices covering the whole brain. The Sobel magnitude edge operator, used for preprocessing, proved adequate for magnetic resonance scans with positive and negative brain/cerebrospinal fluid contrast.     

C-band orthomode transducer for compact and broadband antenna feeders

The design and evaluation of a compact C-band orthomode transducer for dual polarisation satellite communications is presented, covering the bands 3.7-4.2 GHz and 5.925-6.425 GHz (54% of fractional bandwidth separation). Over such a broadband, the main difficulty is to obtain a compact structure able to fulfil the stringent satellite specifications with minimum longitudinal length. The proposed configuration, validated with a tested prototype, also reduces the number of connections and parts in the fabrication, decreasing the passive intermodulation risk and the mass and volume.     

模态逻辑S4的覆盖语义及其完备性

 基于第六种覆盖粗糙集模型提出了模态逻辑S4的覆盖语义,利用覆盖模型与Kripke模型之间的关系,证明了覆盖语义的可靠性和完备性定理.进一步讨论了覆盖语义与Alexandrov拓扑语义之间的关系.证明了覆盖语义与Alexandrov拓扑语义是和谐一致的.     

镍包覆率对固结金刚石磨料研磨垫加工性能的影响

通过化学镀镍的方法,在金刚石磨粒表面包覆一层Ni-P 合金层;采用不同包覆率的金刚石磨料制备固结磨料研磨垫;通过SEM 观察分析金刚石的微观形貌;研究了磨料包覆率对研磨垫加工K9 玻璃过程中的摩擦系数和声发射信号的影响;采用马拉松式试验方法,比较了不同包覆率磨料的研磨垫加工K9 的材料去除速率及研磨后工件的表面粗糙度。结果表明:化学镀镍可以显著改变磨料的表面形貌;研磨过程中的摩擦系数、材料去除速率和工件表面粗糙度均随着包覆率的提高呈现出先增大后减小的趋势;包覆率50%时的金刚石磨料对工件的摩擦力和切入深度最大,研磨垫的磨粒保持与自修整性平衡,加工效率及其稳定性最高。     

Quantitative analysis of doping profile on beveled p-type GaAs structures by micro-Raman spectroscopy

Micro-Raman spectra taken from beveled p-GaAs samples covering a range of concentrations (1×10¹⁸-2×10¹⁹ cm⁻³) have been studied. This study concentrated on the evaluation of the changes of Raman intensities measured in frequency positions of transversal optical and longitudinal optical phonons along the bevel. These changes are dependent on doping concentration and due to this fact we have extracted a calibration function, which will be used to determine the doping concentration in nanometer-thin layers. There are two physical values, which was derived from this study: width of surface-depletion layer and width of space-charge layer. Good correspondence between experimental results and theoretical calculations is the proof of correctness of the model of explanation of the changes of micro-Raman and their analysis. The chemical procedure for preparation of homogeneous oxide-free bevel-shaped p-type GaAs structures with small angle was also developed.     

PHS室内覆盖问题和解决方法

PHS无线市话基站的发射功率很小，仅为移动通信GSM基站的百分之几，所以对服务范围内实现无线信号的无缝覆盖和正确处理区域邻界的交叉覆盖是PHS系统建设中的重要技术课题。本文仅对解决室内覆盖问题的几种方法作一介绍。     

Carbon Nanotube Assisted Enhancement of the Magneto-Optical Kerr Signal in Nickel Thin Films

In this paper, the effect of carbon nanotubes (CNTs) acting as a covering layer on the [Glass/Ni] sample was experimentally investigated. To this end, a 48 nm thick Ni thin film was initially deposited on the glass substrate using a thermal evaporation method. Afterward, a spin-coating method was employed to deposit a thin layer of CNTs on the Ni thin film, thereby forming the [Glass/Ni/CNT] structure. Compared to [Glass/Ni] samples, the presence of CNTs led to 100% and 180% enhancement in the longitudinal Kerr signal of spin-coated samples. Field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, UV–Vis spectra and vibrating-sample magnetometer analyses were employed to characterize and investigate the morphology, elemental analysis, and optical and magnetic characteristics of the resulting structures. As a covering layer, the CNTs enhanced the absorption of light in the UV–visible wavelength range while also amplifying the interaction of light with the Ni layer without seriously changing other magnetic properties of the structure. Accordingly, using a simple approach, the Kerr signal was amplified more than three times compared to that of an uncovered sample, providing useful applications for magnetic sensors.