功率器件引线键合参数研究

引线键合作为芯片封装的关键工艺,其键合质量直接影响器件性能.功率器件普遍采用粗铝丝超声楔形键合,对芯片区域第一键合点和第二键合点键合工艺参数进行了系统研究,并以剪切力作为衡量键合质量的方法,采用单因子分析法,研究各个参数对键合点强度的影响,利用正交试验方法,确定最优参数,并比较两类键合点的差异,为该领域引线键合工艺参数...     

大面阵CCD自动键合参数优化

CCD键合工艺要求硅铝丝依次在Au焊盘和Al焊盘上完成一、二焊的超声键合。文章分别以Au焊盘和Al焊盘为研究对象,通过调整键合中的超声功率和线弧高度参数,在超声功率为20%～50%、线弧高度为1 000～1 800μm范围内,设定48组不同的实验条件进行键合,以键合后拉力测试结果为表征量,采用工序能力指数（Cpk）的统计方法进行归纳比较,从中选取最优实验参数用于大面阵CCD键合工艺,以达到优化键合参数的目的。     

超声功率对25μm铂金丝球形键合强度的影响及键合点质量评价

铂金丝作为低温器件封装中理想的键合丝,其键合质量的优劣决定着整个器件的性能和可靠性。通过25μm的铂金丝球形键合试验,并使用OLYMPUS SMT-6三轴测量显微镜观察键合点形貌并测量第一键合点根部直径。结果表明,当超声功率介于0.96～1.2 W时,增加超声功率有助于提高键合强度,增加工艺稳定性。在文中所设实验条件下,为保证键合强度和工艺稳定性,超声功率设置为1.2～1.28 W时最佳。第一焊点键合球平均直径为2.8 WD(WD表示键合线直径)时,键合强度最大,工艺稳定性最好。总结出了键合点直径与拉力值关系图,从而通过键合点直径来评价键合质量。     

Ni/Pd/Au镀层的键合可靠性

研究了陶瓷外壳不同厚度Ni/Pd/Au镀层的键合可靠性,并分析了金丝球焊、硅铝丝楔焊和粗铝丝楔焊经300℃不同时间贮存后键合强度变化及键合失效模式变化,并与Ni/Au镀层键合进行了对比。研究结果表明,随着Au层厚度的增加,相同键合参数、相同镀层的金丝球焊的键合强度一致性有明显提升,随高温贮存时间增加,Ni/Pd/Au镀层的金丝键合强度一致性变差;相同实验条件下、不同镀层外壳的硅铝丝键合强度基本一致,300℃、1 h贮存后硅铝丝键合强度降低,随着高温贮存时间的增加,硅铝丝键合强度变化不大;随Au层厚度的增加,粗铝丝楔焊键合强度一致性变差,且失效模式主要为键合点脱落。     

先进封装中引线键合前等离子处理

当今的封装工程师们正面临许多挑战,包括降低封装成本策略、成品率提高工艺过程以及错综复杂的无损伤处理、小尺寸器件如多芯片模块、叠层封装和混合电路封装等。为了确保更高的器件可靠性和最小的制造成本,一种经过充分处理的表面因其能够显著提高键合质量和可靠性而成功地在先进封装的引线键合中扮演了重要角色。气体等离子技术能够用于在引线键合前清洗焊盘以改进键合强度和成品率。这是进行表面处理的一种十分有效的方法,它能够显著地改进制造能力、可靠性以及先进封装的成品率。主要讨论了在引线键合前表面处理采用的等离子体的类型及其相关的一些考虑,并评论了实验结果和环氧树脂排放污染的实例细节及有关衬底材料和器件特性。     

多排焊盘外壳封装IC金丝球焊键合技术

在多层多排焊盘外壳封装电路的引线键合中,由于键合的引线密度较大,键合引线间的距离较小,键合点间的距离也较小,在电路的键合中就需要对键合点的位置、质量、键合引线的弧线进行很好的控制,否则电路键合就不能满足实际使用的要求。文中就高密度多层、多排焊盘陶瓷外壳封装集成电路金丝球焊键合引线的弧线控制、外壳焊盘常规植球键合点质量问题进行了讨论,通过对键合引线弧线形式的优化以及采用"自模式"植球键合技术大大提高了电路键合的质量,键合的引线达到工艺控制和实际使用的要求。同时,外壳焊盘上键合的密度也得到了提高。     

功率器件封装工艺中的铝条带键合技术

文章回顾了功率器件封装工艺中几种常见的互连方式,主要介绍了铝条带键合技术在功率器件封装工艺中的主要优点,特别是它应用在小封装尺寸的功率器件中。铝条带的几何形状在一定程度上降低了它在水平方向的灵活性,但却增加了它在垂直方向上的灵活性。铝条带垂直方向的灵活性可以让我们使用最少的铝条带条数来达到功率器件键合的要求。也由于几何形状的不同,铝条带键合具有一些不同于铝线键合的特点,但它对粘片工艺、引线框架和包封工艺的要求与粗铝线键合极其相似,可以与现有的粗铝线键合工艺相兼容,不需要工艺和封装形式的重新设计。     

台面型焊盘的引线键合工艺研究

引线键合工艺是微电子封装的基础工艺,广泛应用于军品和民品芯片的封装。特殊结构焊盘的引线键合失效问题是键合工艺研究的重要方向。文章主要针对台面型焊盘,从热压键合、超声键合、热超声键合原理进行了分析,对台面型焊盘的工艺适应性给出了建议。使用热超声键合工艺进行台面型焊盘的引线键合需要尽可能降低超声功率,避免键合焊盘的机械损伤,并通过平衡其他各变量保证键合点的强度。侧重于热超声键合工艺的应用,分析台面型焊盘与热超声键合过程相关的失效现象,通过样件及小批量试制,对工艺参数进行了优化验证,针对故障件统计分类给出了相应的解决途径。     

硅微波功率管键合失效机理分析

硅微波功率管在生产过程中随机发生大量的键合失效。分析表明,这种硅功率管管芯的焊盘与有源区的连接处介质层容易在键合过程中因为受到金丝的振动冲击而毁坏,因此键合完成后镀金层与介质层无法完整粘合,从而造成微调金丝弧度时发生键合失效。通过加厚焊盘镀金层,避免了金丝对介质层的冲击,提高了硅功率管的键合质量及成品率。     

LTCC基板金丝热超声楔焊正交试验分析

引线键合是微组装技术中的关键工艺,广泛应用于军品和民品芯片的封装。特殊类型基板的引线键合失效问题是键合工艺研究的重要方向。低温共烧陶瓷(LTCC)电路基板在微波多芯片组件中使用广泛,相对于电镀纯金基板,该基板上金焊盘楔形键合强度对于参数设置非常敏感。文章进行了LTCC基板上金丝热超声楔焊的正交试验,在热台温度、劈刀安装长度等条件不变的情况下,分别设置第一键合点和第二键合点的超声功率、超声时间和键合力三因素水平,试验结果表明第一点超声功率和第二点超声时间对键合强度影响明显。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.