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.     

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。     

气密性封装内部水汽含量的控制

气密性封装内部水汽含量过高,会使芯片及电连接系统发生各种物理化学反应,从而造成器件参数不稳定甚至失效,为了保证空封半导体器件的可靠性,生产上不仅需要检测器件封装的气密性,而且需对器件内部水汽含量进行有效的控制。因国内许多生产单位不具备对内部水汽含量进行有效控制的条件和检测设备,因而通过本文的讨论并采用有效防止水汽存在或引入器件的内部,使水汽含量控制在规定的范围内(GJB548A-96、GJB33A-97规定内部水汽含量为:100±5℃,烘24小时以上,小于5000ppmV,且这是最低要求)。因要使器件(未经钝化处理)无因水汽引起的失效,最稳妥的办法是使器件内部水汽含量小于500ppmv;实际上,对大多数器件内部水汽含量若能保持在1000ppmv 以下即能保证器件可靠运行。我们采用合金烧结芯片、合金封帽的器件其内部水汽含量控制在300ppmV 左右,聚合物导电胶装片、合金封帽的在1200ppmV 左右,银玻璃装片、Pb-Sn-Ag 合金封帽的在3000ppmV 左右,即便有某些偏差,亦能保证内部水汽含量控制在较低的范围内,使生产的器件可靠性大大提高,并能100%通过水汽含量检测。     

电阻焊封帽机封帽工艺设计理论

本文着重论述了使用电阻焊封帽机封幔工艺设计理论,并通过应用该理论在汤姆森2400型电阻焊封帽机上封焊各种外形尺寸(最大封焊周长200mm)分立器件和厚薄膜集成电路的实例,证实了该理论的准确性.     

MEMS封装中的封帽工艺技术

MEMS封装技术大多是从集成电路封装技术继承和发展而来,但MEMS器件自身有其特殊性,对封装技术也提出了更高的要求,如低湿,高真空,高气密性等。本文介绍了五种用于MEMS封装的封帽工艺技术,即平行缝焊、钎焊、激光焊接、超声焊接和胶粘封帽。总结了不同封帽工艺的特点以及不同MEMS器件对封帽工艺的选择。本文还介绍了几种常用的吸附剂类型,针对吸附剂易于饱和问题,给出了封帽工艺解决方案,探讨了使用吸附剂、润滑剂控制封装内部环境的方法。     

HG7159封帽工艺及管帽牢固性检测实验

从现有的封帽设备出发，通过一系列的实验，摸索出了一组较好的封帽工艺参数，并建立了一种检测封帽牢固性的有效手段。     

半导体器件和集成电路水汽含量控制的研究

半导体器件和集成电路水汽含量偏高,会影响产品的电性能和可靠性。随着可靠性要求的提高,半导体器件和集成电路的内部水汽含量要求控制在5×10^-3以下。导致水汽含量偏高的原因有3个方面：一是壳体的密封性能差;二是预烘焙不够充分或封帽时控制不当：三是封帽时氮气的纯度不高。针对这3个方面因素分别提出了相应的解决办法,将封装产品的水汽含量稳定地控制在5×10^-3以下,一般内控指标要求在2×10^-3以下,才能保证产品批次性质量要求,从而提高产品的可靠性．     

VLSI低温合金焊料气密封帽技术

一、概述由于环境条件的恶劣，用于宇宙空间、舰船雷达等领域的IC产品通常要求采用高可靠的气密封装形式。一般说来，气密封装可分为金属、陶瓷一金属和陶瓷一玻璃一陶瓷几大类。按其封帽方式又可分为突缘电阻焊、平行缝焊、激光焊接、冷压焊、低温玻璃封帽（俗称“黑瓷”）和低温合金焊封帽等几种。其中，突缘电阻焊主要用于TO封装系列；激光焊接用于大腔体外壳的混合电路封状；VLSI封装主要采用手行缝焊、黑瓷和低温合金焊料焊接几种方式。由于黑瓷封装是采用玻璃作为封接材料，机械强度不能满足军用要求；尽管平行缝焊有诸多优点，但…     

气体放电灯封接技术研究

对石英玻璃等非金属材料与金属材料的几种封接技术进行了介绍。初步分析了封接过程中的重要环节应当采用的工艺手段,列举了各种封接方式的优缺点,介绍了帽罩封接方式新工艺和钼箔封接方式等的改进方法。以期在现有技术基础上,进一步完善光源的封接技术,逐步提高产品的真空气密性、热稳定性、机械强度等可靠性指标和使用寿命。     

密封半导体器件中多余物的提取和控制研究

高低温循环可以加速暴露出密封半导体器件中的可动多余物。为了提取多余物,改进了传统开洞PIND法。第一,通过对大量的金属封装进行开孔试验,得出最佳盲孔厚度为25~30μm的重要工艺参数,为指导金属封装多余物的提取提供量化依据;第二,在开孔工艺中用三棱锥针取代传统的圆锥针,减少了因开孔产生多个卷边易产生封帽碎屑的风险;第三,采用有色有机溶剂对封帽局部染色的工艺标识封帽碎屑,改善传统方法中难以区分外引入物和内多余物的缺陷。介绍了将3种新工艺应用于一种微波功率管的案例,成功地提取出金锡焊料多余物,整改工艺缺陷后PIND第一次失效率得到大幅的降低,论证了开洞PIND法是一种提取腔体半导体器件多余物的科学、可靠的技术方法,其改进工艺还在不断地涌现。     

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     

平行缝焊盖板镀层结构的热分析

平行缝焊是陶瓷封装中应用最为广泛的高可靠性气密性封装方式之一。由于焊接过程中,盖板表面镀层会发生熔化、破坏等过程,可伐基底会被暴露在环境中,导致盐雾腐蚀失效。利用Abaqus有限元分析软件,选择2种代表性的可伐盖板镀层结构,分析不同加载温度条件下可伐盖板及其表面镀层的温度分布。仿真结果表明,当可伐盖板采用Ni/Au的镀层结构时,控制焊接温度范围为1200~1400℃,有希望保证平行缝焊耐盐雾腐蚀可靠性,并给出其耐盐雾腐蚀机理。     

基于平行缝焊工艺的AuSn合金焊料封盖技术研究

为了解决聚合物粘结电路的质量与长期可靠性问题,提出了一种采用平行缝焊工艺对AuSn合金焊料熔封器件进行封盖的新方法。通过对平行缝焊工艺的深入研究,解决了该类器件封盖的气密性与外观质量问题,从而找到了一种有效解决熔封外壳组装的低温聚合物粘结电路水汽含量、抗剪强度、键合强度控制的新方法。     

Exposed Die-Top Encapsulation Molding for an Improved High- Performance Flip Chip BGA Package

The recent advancement in high- performance semiconductor packages has been driven by the need for higher pin count and superior heat dissipation. A one-piece cavity lid flip chip ball grid array (BGA) package with high pin count and targeted reliability has emerged as a popular choice. The flip chip technology can accommodate an I/O count of more than five hundreds500, and the die junction temperature can be reduced to a minimum level by a metal heat spreader attachment. None the less, greater expectations on these high-performance packages arose such as better substrate real estate utilization for multiple chips, ease in handling for thinner core substrates, and improved board- level solder joint reliability. A new design of the flip chip BGA package has been looked into for meeting such requirements. By encapsulating the flip chip with molding compound leaving the die top exposed, a planar top surface can be formed. A, and a flat lid can then be mounted on the planar mold/die top surface. In this manner the direct interaction of the metal lid with the substrate can be removed. The new package is thus less rigid under thermal loading and solder joint reliability enhancement is expected. This paper discusses the process development of the new package and its advantages for improved solder joint fatigue life, and being a multichip package and thin core substrate options. Finite-element simulations have been employed for the study of its structural integrity, thermal, and electrical performances. Detailed package and board-level reliability test results will also be reported     

平行缝焊工艺抗盐雾腐蚀技术研究

抗盐雾腐蚀是提高集成电路封装可靠性的重要手段之一.根据金属腐蚀机理,通过优化封焊工艺和AuSn合金焊料平行缝焊封盖工艺,以及在封盖后再次进行电镀修复损伤等措施,提高了平行缝焊集成电路的杭盐雾腐蚀能力.     

Reliability assessment of delamination in chip-to-chip bonded MEMS packaging

The bond layer is often the weakest link in the reliability of chip packages in the integrated circuit (IC) industry. Micro-electrical-mechanical systems (MEMS) packages are no exception to this trend. This paper presents a nondestructive methodology for determining delamination in chip-to-chip bonded MEMS. Experimental methods are used to determine the adhesive layer strength in samples subjected to environmental testing, and the reliability of the bonding layer is investigated. A simulation is performed using inputs from scanning acoustic microscopy, and simulation model results are correlated with the experimental die shear measurements to establish the validity of the nondestructive methodology for determining adhesive layer strength.     

X射线在陶瓷气密封装空洞检查中的不足

在集成电路的陶瓷气密封装中，往往使用X射线照相技术来检查密封区的空洞情况并由此判断密封质量的好坏。通常情况下，X射线的检测结果是可信的，但是也存在由于某种原因导致焊接空洞无法为X射线所探测的情形。此外，部分具有底部热沉的陶瓷外壳，其热沉材料本身对X射线的吸收很大，会对焊接区存在的空洞的成像进行覆盖，并造成漏判。另外，X射线对于不同层面的空洞会进行图像叠加，从而无法对空洞部位进行准确定位。文中从X射线照相的原理上对此类X射线照相中的空洞漏判等现象进行了分析和探讨。     

Moisture evolution analysis of sealing glasses used in integrated circuit packaging

Free moisture in the cavity of a sealed hermetic integrated circuit is considered an important reliability hazard. The contribution to the cavity moisture by the packaging materials can be studied effectively using the technique of moisture evolution analysis (MEA). The technique involves passing a dry carrier gas over the sample at high temperatures and measuring its moisture uptake coulometrically. The standard moisture evolution technique has been modified to quantify the kinetics of moisture evolution from sealing glasses used for hermetic sealing of I.C. packages which are primary contributors to total cavity moisture. It is also shown that once the moisture evolution mechanisms are understood, the technique of moisture evolution analysis can be correlated to a more complex, industry standard method for free cavity moisture measurement in a sealed hermetic package (RGA-mass spectrometry). MEA can therefore be used for the process control and prediction of free cavity moisture of hermetically sealed I.C. packages.     

100 μm Pitch flip chip on foil assemblies with adhesive interconnections

In this work the reliability of flip-chip-on-flexible substrate packages with electrically conductive adhesive as first level interconnections is studied. The pitch of the interconnections ranges from 300 to 100 μm with prospects to smaller pitches. The Physics-of-Failure approach is used to determine the nature of such an interconnection and hence the factors that will influence the performance of these packages. The results indicate that moisture is a more important stress factor than temperature. In particular cyclic exposure to high and low moisture levels may lead to degradation of the electrical interconnection. As failure mechanism, reduction of the compressive force that holds the interconnection together is proposed. Further, the proper combination of materials––based on their in- and out-diffusion rates for water––determines the resistance of the packages to reflow-soldering.