航空电子元器件二次筛选与印制板组件检验

本文就如何利用外加应力或用检测手段进行二次筛选,将早期失效的元器件从整批产品中剔除,从源头上确保电子产品的质量和寿命.以及在元器件质量和可靠性得到充分保证的前提下,如何不断提高印制板组件加工和检验水平进行了探讨.通过二次筛选以及提高印制板组件加工和检验水平,可以提升模块乃至整机的质量从而使航空电子产品的质量得到充分保证.     

Pb-free surface-finishing on electronic components’ terminals for Pb-free soldering assembly

Pb-free solderable surface finishing is essential to implement Pb-free solder assembly in order to meet with the growing demand of environmental consciousness to eliminate Pb from electronic products. Two types of widely applicable Pb-free surface finishing technologies are developed. One is the multilayer-system including Pd with Ni undercoat. Heat-resistance of Pd enables whole-surface-plating on to leadframe before IC-assembling process. The other is the double-layer-system with low-melting-point-materials, for example, thicker Sn underlayer and thinner Sn-Bi alloy overlayer, dilutes Sn-Bi alloy’s defects of harmful reactivity along with substrate metal and mechanical brittleness with keeping its advantages of solder-wettability and no whisker.     

Fabrication and characterization of micromachined rectangularwaveguide components for use at millimeter-wave and terahertzfrequencies

The fabrication and characterization of micromachined reduced-height air-filled rectangular waveguide components suitable for integration is reported in this paper. The lithographic technique used permits structures with heights of up to 100 μm to be successfully constructed in a repeatable manner. Waveguide S-parameter measurements at frequencies between 75-110 GHz using a vector network analyzer demonstrate low loss propagation in the TE₁₀ mode reaching 0.2 dB per wavelength. Scanning electron microscope photographs of conventional and micromachined waveguides show that the fabrication technique can provide a superior surface finish than possible with commercially available components. In order to circumvent problems in efficiently coupling free-space propagating beams to the reduced-height G-band waveguides, as well as to characterize them using quasi-optical techniques, a novel integrated micromachined slotted horn antenna has been designed and fabricated, E-, H-, and D-plane far-field antenna pattern measurements at different frequencies using a quasi-optical setup show that the fabricated structures are optimized for 180-GHz operation with an E-plane half-power beamwidth of 32° elevated 35° above the substrate, a symmetrical H-plane pattern with a half-power beamwidth of 23° and a maximum D-plane cross-polar level of -33 dB. Far-field pattern simulations using HFSS show good agreement with experimental results     

Active control of boundary conditions for dynamic thermal characterization of electronic components

This paper presents a practical realization of the system for the active control of boundary conditions during the dynamic thermal characterization of electronic components. The control of boundary conditions is exercised by the dual cold plate cooling assembly equipped with Peltier thermo-electric modules and an appropriate control circuit. Additionally, a tensometer bridge is used to assure the parallel alignment of surfaces and to adjust the contact thermal resistance between particular layers. The operation of the entire control system is illustrated based on a practical example where Peltier module currents are adjusted in real time so as to impose isothermal or constant heat flux boundary conditions on a power diode package surface during measurements performed with time varying power dissipation in the device.     

电子装配与调试的解决方案

我一直从事中职学校电子技术的实验教学和指导电子技术装备与调试技能竞赛工作,根据自己多年来指导学生在省、市技能大赛的实验教学经验,简单分析如何指导学生参加电子装配与调试技能大赛,如何让学生从一个厌学到好学,从一个浮躁的初中生如何转变成一个勤于思考,敢于创新,善于研究的中职好学生.     

A diketopyrrolopyrrole containing molecular semiconductor: Synthesis,characterization and solution-processed 1D-microwire based electronic devices

Highly oriented 1D-microwires of a diketopyrrolopyrrole (DPP) based semiconductor i.e. DPP(CBZ)₂ (Carbazole capped DPP) were synthesized, characterized and applied to the fabrication of organic optoelectronic devices. 1D-microwires of DPP(CBZ)₂ were prepared by solution processing on capillary tubes serving to pin solution. A bottom-gate, top-contact field-effect transistor employing 1D-microwire and polymeric gate dielectric showed a hole mobility of 1.24 × 10⁻² cm²/V s, an on-to-off drain current ratio (I_on/I_off) of 4.7 × 10³ and subthreshold slopes of 4 V/dec under ambient conditions. Under white light, a photosensitivity of 800 at V_G = −40 V and photoresponsivity of 830 mW/A were achieved. This work demonstrates the potential of this new molecule and the solution method for use in various opto-electronic devices such transistors, photosensors and photovoltaics.     

纳米线、纳米管的制备、表征及其应用

在高度集成化浪潮的推动下,现代技术对纳米尺度功能器件的需求将越来越迫切。纳米线、纳米管等一维材料作为纳米器件中必不可少的功能组件,在纳米研究领域中的地位显得愈发重要。本文从一维纳米材料的研究范畴入手,介绍了纳米线、纳米管的制备方法,技术要点以及各种相关表征方法,并涉及了当前一维纳米材料的一些应用研究,为基于纳米线、纳米管功能器件的研制提供前期参考。     

Fabrication and characterization of NEMS

We proposed a called“nano-fabrication based on MEMS technology”approach to realize the typical nano-electro- mechanical structures,such as integrated nano probe,ultrathin cantilever,silicon nano wire,and doubly clamped nano beam, to demonstrate the feasibility and advantages.We also introduced the characterization of nano structures based on laser vibrometer and piezoresistive effect,the latter method was first time applied to investigate a doubly daped nanobeam with a thickness of about 200 nm.     

Digital simulation of electronic components

A method is described for simulating resitive networks by digital (hardware) techniques. Advantages of the method include increased accuracy of component specifications and freedom from aging effects. Other components may be simulated similarly.     

铁电微管的制备与表征

采用化学浸润法在多孔硅模板上制备了锆钛酸铅(PbZr0.52Ti0.48O3,PZT)铁电微管,X射线衍射分析表明铁电微管为钙钛矿结构.运用扫描电子显微镜和原子力显微镜对铁电微管的微现形貌进行了观察,其姑果显示两种方法所测得的铁电微管直径不同.利用压电响应力显微镜观察到了铁电微管的电畴图像,并测得了铁电微管的微区电滞回...     

Fabrication and characterization of neodymium-doped glasswaveguides

Waveguides prepared in neodymium-doped lithium-silicate glass by silver-ion exchange are discussed. Refractive index change and diffusion coefficient due to ion exchange are determined. It is observed that silver-ion exchange does not influence the emission wavelength of neodymium-doped glass     

直升机机载电子设备可靠性综合评估

通过引入由分系统的可靠性参数综合评估系统可靠性参数的理论模型，对直升机机载电子设备的可靠性进行了综合评估，并通过计算举例进行验证，说明运用这种理论模型对直升机机载电子设备可靠性进行评估的可行性。     

电子计算机的装配调试技术研究

随着国民经济的不断增长和科学技术的不断创新,我国电子计算机行业发展得到了质的飞跃。电子计算机作为社会大众生活工作中必不可缺的一部分,是人们及时获取各项信息的重要工具。因此,为了最大化发挥出电子计算机的各项功能作用,就必须充分做好它的装配调试工作,确保计算机系统能够安全可靠地持续运行。文章对电子计算机的装配调试技术展开分析与探讨。     

对电子元器件的失效机理分析

本文对电子元器件失效机理进行分析和探讨,旨在为元器件以及设备的检修提供理论支持.     

Fabrication, assembly, and testing of RF MEMS capacitive switches using flexible printed circuit technology

A novel approach for cost effective fabrication, assembly, and packaging of radio-frequency microelectromechanical systems (RF MEMS) capacitive switches using flexible circuit processing techniques is reported. The key feature of this approach is the use of most commonly used flexible circuit film, Kapton-E polyimide film, as the movable switch membrane. The physical dimensions of these switches are in the mesoscale range. For example, electrode area and gap height of a capacitive shunt switch on coplanar waveguide are 2 /spl times/ 1 mm/sup 2/ and 43 /spl mu/m, respectively. Pull-down voltage is in the range of 90-100 V. In the ON state (up-position), the insertion loss is less than 0.3-0.4 dB up to 30 GHz. In OFF state (down-position), the isolation value is about 15 dB at 12 GHz and increases to 36 dB at 30 GHz. These switches are uniquely suitable for batch integration with printed circuits and antennas on laminate substrates.     

几款新型电源器件介绍

凌特公司（Linear　Technology Corp.）在2001年9月发布了几款电源新器件。它们是LTC1911-1.8/1.5、LTC3405、LT1765及LT1956。本文对这些新器件做一个简介。     

假冒电子元器件的识别与分析

对假冒电子元器件的分类、危害和检测手段进行了阐述。电子元器件的用户可借助目视镜检、X射线、扫描超声显微镜和伏安曲线追踪仪等实验手段,对可疑电子元器件进行辨别,保证产品的质量和可靠性。     

超材料(metamaterials)在电子元件中的应用

超材料(metamaterials)指的是一些呈现出天然材料所不具备的超常物理性质的人工复合材料。它们的超常特征来源于其中人工制备的、特殊的非均匀插入结构所导致的物理响应。介绍了近年来发展出的超材料包括左手材料、"隐身斗篷"和光子晶体等,对其在电子元件领域中的应用进行了评述和展望。     

Fabrication techniques and applications of flexible graphene-based electronic devices

In recent years, flexible electronic devices have become a hot topic of scientific research. These flexible devices are the basis of flexible circuits, flexible batteries, flexible displays and electronic skins. Graphene-based materials are very promising for flexible electronic devices, due to their high mobility, high elasticity, a tunable band gap, quantum electronic transport and high mechanical strength. In this article, we review the recent progress of the fabrication process and the applications of graphene-based electronic devices, including thermal acoustic devices, thermal rectifiers, graphene-based nanogenerators, pressure sensors and graphene-based light-emitting diodes. In summary, although there are still a lot of challenges needing to be solved, graphene-based materials are very promising for various flexible device applications in the future.