高强度带光窗光电外壳设计

选取窗口结构强度相对较弱的圆形平面玻璃光窗外壳,就该类外壳最薄弱的带光窗管帽受力状态进行了有限元分析,根据强冲击下结构与应力的变化趋势优化设计了管帽结构,结果显示经结构优化的管帽能承受1×104 g的强冲击,满足光电器件封装的高强度要求。     

用电镀法制造硅靶铜导电帽的研究

具有导电帽的硅靶视像管可以减小其惰性,并提高其抗晕光的能力。本文着重对用电镀法制造硅靶铜导电帽的有关问题如:电镀液的组成;电镀槽、电极结构;电流;硅靶表面等诸因素对铜导电帽质量的影响进行了分析。结果表明用电镀法制备硅靶导电帽是一种成本低、无毒害、无污染的简便易行的方法。     

基于改进Faster R-CNN的接触网管帽目标定位算法

为了改善接触网管帽这类小尺度部件在故障检测过程中定位困难的情况,提出一种基于改进Faster R-CNN的接触网管帽目标定位算法.通过K均值聚类算法(K-means)对region proposal network (RPN)层中生成anchor boxes的比例及面积进行改进,所提算法在定位接触网管帽这类小部件上具有...     

瞬态超高温MEMS石墨烯温度传感器设计

针对炮膛、航空发动机等设备对于超高温瞬态温度测量的需要，设计了一种量程达3000℃的瞬态石墨烯温度传感器，传感器由石墨烯敏感芯片、管帽、管壳三部分组成，利用管帽传热的同时进行热阻隔。使用ANSYS仿真软件对传感器管帽(传热膜片)厚度进行优化，并进行强度安全校核。结果表明：在脉宽10 ms、峰值3000℃的正弦温度冲击波作用下，管帽膜厚为2.7 mm时，该传感器可以发挥石墨烯最佳性能，且可以满足400 MPa的高强度。最后，利用仿真结果优化得到了外推对应关系。本论文设计的石墨烯MEMS温度传感器具有量程宽、针对性强、稳定性高等特点，可为石墨烯传感器应用于超高温瞬态测量领域提供可行性方案。     

垂直腔面发射激光器的TO封装工艺操作误差分析

采用FRESNEL光学软件和MATLAB编程,详细分析了垂直腔面发射激光器的TO封装工艺操作误差对耦合效率的影响.发现在芯片横向偏移、芯片倾斜和管帽倾斜这三种操作误差中,管帽倾斜对封装组件的耦合效率影响最大.     

垂直腔面发射激光器的TO封装工艺操作误差分析

采用FRESNEL光学软件和MATLAB编程,详细分析了垂直腔面发射激光器的TO封装工艺操作误差对耦合效率的影响.发现在芯片横向偏移、芯片倾斜和管帽倾斜这三种操作误差中,管帽倾斜对封装组件的耦合效率影响最大.     

封帽机同轴精度分析及结构改进

为了提高封帽机同轴精度,满足封焊产品性能要求,对封帽机同轴精度进行了分析,并对封帽机烘箱容积、焊接系统结构、上下料方式、手套箱结构等进行了改进,通过分析和改进,提高了封帽机同轴精度,满足了封焊产品性能,保证了设备运行稳定性,提高了生产效率。     

问与答

最近看了多篇有关应用FU-29功率管的发烧音响文章，被其优良的性能所吸引，于是购买了FU-29来组装，后来却被其管帽连接难住了，好的管帽套价格昂贵，甚至要100多元一个，比FU-29还贵许多，如果用廉价产品，     

应用超声热压法实现对微波超小型器件的无边缘封帽

本文介绍一种对微波器件实现无边缘封帽的方法.利用超声热压方法来完成对超小型微波器件的无边缘封帽,结果表明用这种方法封帽后的器件其气密性(即漏气率Q≤10~(-6)托升/秒),成品率能达到90%以上,并能通过C级的振动、冲击、离心、变频、热冲、温度循环、加速热潮等项可靠性考核.同时对封帽后的器件进行了抗折强度和抗拉强度的试验.结果表明封帽边缘的抗折强度和抗拉强度高达200公斤/厘米~2,大大地超过了器件本身对管壳所提出的强度要求.采用本法对微波器件实现无边缘封帽,无需对器件管芯加热,使用的超声功率仅为0.3瓦左右,管帽受热时间仅为3秒到5秒,封管温度为340℃到360℃,因此,对器件的性能毫无影响.实践证明,本文所介绍的方法完全可以应用于微波超小型器件的封帽,并且具有效果好、封帽速度快等一系列优点.目前本法已应用到某些同轴型和微带型器件的产品定型和批量生产之中.     

耿氏二极管的几种失效模式及其机理分析

介绍了耿氏二极管的工作原理及其基本结构,通过外观检查、电特性测试、环境试验、内部目检、X射线及扫描电镜(SEM)检查等失效分析手段和方法,针对耿氏二极管在使用过程中较常出现的短路、开路及管帽脱落等失效模式及失效机理进行了分析和讨论,并根据上述几种失效模式对应的机理,指出了避免失效的一些措施,对该器件的制造商和使用者具有一定的参考价值.     

Correlation Between Sn Grain Orientation and Corrosion in Sn-Ag-Cu Solder Interconnects

The impact of a marine environment on Sn-Ag-Cu interconnect reliability is examined using salt spray exposure followed by thermal cycling. Sn-Ag-Cu solder alloy wafer-level packages, with and without pretreatment with 5% NaCl salt spray, were thermally cycled to failure. The prior salt spray reduced the characteristic lifetime of the Sn-Ag-Cu solder joints by over 43%. Although Sn-based materials show strong resistance to corrosion, the nature of localized corroded areas at critical locations in the solder joint caused significant degradation in the Sn-Ag-Cu solder joints. An important link between the corrosion path and Sn grain orientation was observed using orientation imaging microscopy (OIM). A strong correlation between the corrosion path and grain orientation was identified, indicating that the corrosion attack preferentially followed the basal plane of the Sn lattice.     

Multi-physics modeling in virtual prototyping of electronic packages––combined thermal, thermo-mechanical and vapor pressure modeling

The realization of virtual prototyping of electronic packages depends on the capability and reliability of multi-physics modeling. This paper focuses on the methods and solutions of combined thermal and thermo-mechanical modeling. The package-level thermal behaviors for various kinds of packages are discussed first through the thermal simulation. The impact of internal package design on thermal performance is highlighted. Then the methods and solutions of combined thermal and thermo-mechanical modeling are addressed in detail. The strong interactions of thermal and mechanical simulations, as well as the trade-off between thermal and mechanical designs are discussed through two case studies. The benefit of moisture behavior modeling for the package design is also briefed in this paper.     

半导体激光器高速同轴封装设计

在光纤接入网等光通信领域,低成本高速同轴封装半导体光电器件有着非常重要的作用。对于高速TO-can激光器(LD),由于已进入微波工作频段,封装以及相关元件的分布参数已经成为制约高速激光器性能的主要参数之一,分析了同轴封装结构的技术特点,建立了激光器器件及封装相关元件的等效电路模型,利用商用CAD分析软件对其进行了模拟和优化设计,为半导体激光器高速同轴封装设计的工艺方案、封装材料的选择提供了依据,并据此进行了部分相关实验。     

Dynamic strength of anisotropic conductive joints in flip chip on glass and flip chip on flex packages

The work presented in this paper focuses on the behavior of anisotropically conductive film (ACF) joint under the dynamic loading of flip chip on glass (COG) and flip chip on flexible (COF) substrate packages. Impact tests were performed to investigate the key factors that affect the adhesion strength. Scanning electron microscopy (SEM) was used to evaluate the fractography characteristics of the fracture. Impact strength increased with the bonding temperature, but after a certain temperature, it decreased. Good absorption and higher degree of curing at higher bonding temperature accounts for the increase of the adhesion strength, while too high temperature causes overcuring of ACF and degradation at ACF/substrate interface––thus decreases the adhesion strength. Higher extent of air bubbles was found at the ACF/substrate interface of the sample bonded at the higher temperature. These air bubbles reduce the actual contact area and hence reduce the impact strength. Although bonding pressure was not found to influence the impact strength significantly, it is still important for a reliable electrical interconnect. The behaviors of the conductive particles during impact loading were also studied. From the fracture mode study, it was found that impact load caused fracture to propagate in the ACF/substrate interface (for COG packages), and in the ACF matrix (for COF packages). Because of weak interaction of the ACF with the glass, COG showed poor impact adhesion.     

Effect of Size of Lid-Substrate Adhesive on Reliability of Solder Balls in Thermally Enhanced Flip Chip PBGA Packages

Six design cases of lid-substrate adhesive with various combinations of widths and heights were analyzed to investigate how the size of the adhesive affects the reliability of the solder balls of thermally enhanced flip chip plastic ball grid array (FC-PBGA) packages in thermal cycling tests. Analysis results were compared with data on the reliability of conventional FC-PBGA packages. Thermal-mechanical behavior was simulated by the finite element (FE) method and the eutectic solder was assumed to exhibit elastic-viscoplastic behavior. The temperature-dependent nonlinear stress/strain relationship of the adhesive was experimentally determined and used in the FE analysis. Darveaux's model was employed to obtain the predicted fatigue life of the solder ball. Simulation results reveal that the fatigue life of the solder balls in thermally enhanced FC-PBGA packages is much shorter than that in conventional FC-PBGA packages, and the life of solder balls increases with both the width and the height of the adhesive. However, the effect of the width of the adhesive on the reliability of the solder ball is stronger than that of the height. Moreover, increasing either the width or the height reduces the plastic strain in the adhesive at critical locations, indicating that the reliability of the adhesive can be improved by its size. The predicted results of the life of solder balls for some selected studied packages are also compared with experimental data from thermal cycling tests in the paper     

Board level reliability assessment of chip scale packages

A large program had been initiated to study the board level reliability of various types of chip scale package (CSP). The results on six different packages are reported here, which cover flex interposer CSP, rigid interposer CSP, wafer level assembly CSP, and lead frame CSP. The packages were assembled on FR4 PCBs of two different thicknesses. Temperature cycling tests from −40°C to +125°C with 15 min dwell time at the extremes were conducted to failure for all the package types. The failure criteria were established based on the pattern of electrical resistance change. The cycles to failure were analyzed using Weibull distribution function for each type of package. Selected packages were tested in the temperature/humidity chamber under 85°C/85%RH for 1000 h. Some assembled packages were tested in vibration condition as well. In all these tests, the electrical resistance of each package under testing was monitored continuously. Test samples were also cross-sectioned and analyzed under a Scanning Electronic Microscope (SEM). Different failure mechanisms were identified for various packages. It was noted that some packages failed at the solder joints while others failed inside the package, which was packaging design and process related.     

Experimental and numerical analysis of BGA lead-free solder joint reliability under board-level drop impact

Board-level solder joint reliability is very critical for handheld electronic products during drop impact. In this study, board-level drop test and finite element method (FEM) are adopted to investigate failure modes and failure mechanisms of lead-free solder joint under drop impact. In order to make all ball grid array (BGA) packages on the same test board subject to the uniform stress and strain level during drop impact, a test board in round shape is designed to conduct drop tests. During these drop tests, the round printed circuit board assembly (PCBA) is suffered from a specified half-sine acceleration pulse. The dynamic responses of the PCBA under drop impact loading are measured by strain gauges and accelerometers. Locations of the failed solder joints and failure modes are examined by the dye penetration test and cross section test. While in simulation, FEM in ABAQUS software is used to study transient dynamic responses. The peeling stress which is considered as the dominant factor affecting the solder joint reliability is used to identify location of the failed solder joints. Simulation results show very good correlation with experiment measurement in terms of acceleration response and strain histories in actual drop test. Solder joint failure mechanisms are analyzed based on observation of cross section of packages and dye and pry as well. Crack occurred at intermetallic composite (IMC) interface on the package side with some brittle features. The position of maximum peeling stress in finite element analysis (FEA) coincides with the crack position in the cross section of a failed package, which validated our FEA. The analysis approach combining experiment with simulation is helpful to understand and improve solder joint reliability.     

Dynamics of Broad-Area Semiconductor Lasers With Short Optical Feedback

The dynamics of filamentations in broad-area semiconductor lasers with short optical feedback were numerically studied. Regular pulse packages similar to those observed in narrow-stripe edge-emitting semiconductor lasers were found as the feedback reflectivity is increased. However, the regular pulse packages consisted of a periodic envelope of the external cavity frequency and fine pulse trains of periodic filaments, which is different from the regular pulse packages observed in narrow-stripe edge-emitting semiconductor lasers. From the analysis for spatio-temporal near-field patterns, we found periodic undulations of the spatial and temporal filament sizes as the external mirror reflectivity was changed. We also investigated filtered optical feedback, where a part of the emitted beam is fed back into the laser cavity. The time-averaged near-field pattern was found to have a strong dependence on the feedback level in the case of spatial filtered optical feedback.     

Hygrothermal Failures From Small Defects in Lead-Free Solder Reflowed Electronic Packages

Steam-driven delamination failure is a main failure mode in electronics packages during solder reflow. Steam pressures built up within interfaces in packages are sensitive functions of the reflow temperature. The switch to lead-free soldering will raise re-flow temperature by more than 20degC and double the equilibrium saturated steam pressure within defects in the package. The effects of saturated steam driven interfacial failure was analyzed using finite element in this study. Analyses revealed that packages which are thin and made using high thermal conductivity materials are at higher risk of failure than conventional packages made using standard materials. This suggests that electronics made with thick and inexpensive encapsulants are less prone to failure when switched to lead-free solder. Portable and mobile electronics which have low profiles and are made of high thermal conductive encapsulants are at higher risk when switched to lead-free solder reflow. Moreover, the study found that the critical temperature for failure is dependent on the defect size in the package. Reduction of initial defect size can reduce failures in high risk packages in lead-free solder reflow.     

一种提高微电路外壳使用可靠性的方法

简要分析了白瓷双列直插外壳的失效模式和失效机理，并进行了模拟实验，通过对实验结果的分析，提出对成品微电路进行二次电镀能够提高其外壳的使用可靠性。