声表面波器件压电芯片粘接工艺的可靠性研究

对声表面波(SAW)器件失效模式以及SAW器件粘片分离模式进行了初步分类和探讨，通过对粘片工序几种分离模式的对比试验，总结了一套针对该工序的较为完整的粘片可靠性增长的控制措施。     

换能器与固体微声器件

0327700声表面波器件压电芯片粘接工艺的可靠性研究(刊,中]/陈台琼//电子质量.—2003,(6).—89-91(E3)本文对声表面波(SAW)器件失效模式以及SAW器件粘片失效模式进行了初步分类和探讨。通过对粘片工序几种失效模式的对比试验,总结了一套针对该工序的较为完整的粘片可靠性增长率控制措施。     

塑封碳化硅肖特基二极管粘片工艺

粘片工艺是塑封碳化硅肖特基二极管封装中的关键工艺,实现了芯片背面金属与引线框架的物理连接与电连接,对器件的参数以及可靠性影响较大。我们发现器件生产中或者器件可靠性的多种失效模式都产生于粘片工艺。我们通过对焊料成分、拍锡头结构,工艺参数的优化等,使器件的品质大大提升。     

声表面波器件的失效机理和可靠性问题

SAW器件的应用日益广泛,它的可靠性问题也随之而引起重视.本文分析了电场、温度、材料及工艺等对器件可靠性的影响,对三种重要的失效机理即AI膜的腐蚀、迁移和LiNbO_3压电晶片的微裂进行了讨论并介绍了SAW器件生产中的质量管理、可靠性试验和失效分析等.本文着重指出:要生产高可靠性的SAW器件,必须妥善处理材料、工艺中的一系列问题.     

塑封TO-220、TO-263产品封装工艺改进

通过多年的塑封TO-220、TO-263封装的功率型器件的生产实践,我们发现器件的失效模式多与两个问题相关。一是粘片工艺的控制,二是塑封分层的控制。粘片实现了芯片背面金属与引线框架的物理连接与电连接,对器件的参数以及可靠性影响较大。通过对焊料成分、拍锡头结构,工艺参数的优化等,使器件的品质大大提升。塑料分层问题可引起器件的多种失效模式。通过优化塑封料的各种成分比例,优化引线框架结构,控制引线框架的表面态,可以非常明显的提高器件的抗分层能力。通过超声扫描证实经过优化后的器件分层情况发生了非常明显的改善。     

声表面波后工序环节对器件可靠性影响的研究

报道了声表面波（SAW）后工艺环节对基片粘接剂的固化程度、不同制作条件、不同封帽环境制作的滤波器，通过在高温、负温以及高温加速老化后的器件性能变化，来研究SAW器件的可靠性。结果表明：器件的插入损耗随老化时间逐渐增加；器件插入损耗的稳定性明显依赖于封装的湿度和器件表面的状态；器件的气密性随老化时间，器件的老化会更明显。结论是：器件必须要在清洁（净化）的环境中制作，清洁的器件表面第一重要；干燥的封装是器件性能稳定的重要条件；器件、组件老化到一定程度后，将不会有较大的性能变坏现象出现。这些研究成果，对防止或控制高性能器件失效、提高SAW器件可靠性将具有指导意义。     

国外简讯

AlN/Si声表面波器件 SAW器件的一个新的发展分支是与半导体相结合的集成化技术。在Si片上溅射ZnO薄膜以激励和传播SAW已进行过大量的工作。AlN也是一种适用于SAW器件的压电薄膜材料,而且它的化学稳定性、机械强度、声速和机电耦合系数可能还优于ZnO膜,这就使得AlN膜有可能用作单片SAW器件以取代ZnO。 AlN膜的生长方法较多,如CVD法、RF溅射等。这些方法都要求基片温度在1000℃以上。在较低温度下在玻璃和兰宝石基片成功地沉积AlN膜,只是在最近才用反应溅射实现的。美国珀杜大学电工系L.G.Pearce等人用有磁控阴极的MRC-8620型RF平面溅射系统沉积了高度取向的AlN膜,并制成了几种新型的AlN/Si SAW器件。     

化学腐蚀对声表面波器件性能影响分析

Al膜的化学腐蚀直接影响声表面波器件的可靠性,造成器件功能性失效。该文对SAW器件Al膜的化学腐蚀的机理、过程、产生的条件、对器件性能及可靠性的影响进行了分析,并对其进行了试验验证和检测,以及在生产过程中如何加以预防和控制进行了阐述。     

日本公共电信系统的SAW器件应用

评述了投入实际服务的公共电信系统所用的SAW器件,并介绍了SAW器件的应用前景。 F-400M光纤传输系统的400MHz定时振荡回路和汽车电话系统的145MHz SAW谐振器稳定压控振荡器是现在实际应用中仅有的两种器件。但是,由于它们工作于高频基波模式,具有良好的重复性和老化性能,所以器件的应用在不断地增加。     

共线TE-TM模式转换器中的陀螺效应

简要介绍了声表面波(SAW)陀螺效应及TE-TM模式转换理论,提出了检测SAW陀螺效应的一种新方法.该方法的核心是通过模式耦合理论的作用,把SAW陀螺效应引起的器件轻微形变反应到器件耦合效率的变化中,通过检测特定偏振态的出射光强度进而推算出陀螺的转动角速度.讨论了检测SAW陀螺效应的实验方案,设计了检测系统,并推导出了陀螺效应的系统测量公式.     

Behavior of Anisotropic Conductive Film Joints Bonded with Various Forces under Temperature Fluctuation

The effects of bonding force and temperature fluctuations on the failure behaviors of anisotropic conductive film (ACF) interconnections were analyzed. Thermal shock testing was conducted to realize the temperature fluctuation environment. Two primary modes of failure were detected after thermal shock testing: formation of a non-conductive gap between conductive particles and the Au bump or Ni/Au-plated Cu pads, and delamination of the adhesive matrix from the plated Cu pads on flexible substrates. The failure mode was affected mainly by the variation in the bonding force. The main failure mode of the thermally shocked ACF joints was the non-conductive gap for the joints with low bonding forces and adhesive matrix delamination for the joints with high bonding forces. The difference in failure modes is critically discussed.     

An improved interconnection technique

This paper deals with an improved interconnection technique for use with thin film hybrid ICs, SAW devices and semiconductor devices based on shallow diffusions eg. MOS-FETS $\text{h}\text{f}$ transistors etc., In this technique, the thin film strips of specific width and length (or shape) formed photolithographically on specific substrates are floated off and used for bonding the contact pads to the package leads by thermocompression/ultrasonic bonding methods. The technique has been successfully used for bonding SAW devices and discrete MOS-FETS.     

声表面波器件小型化技术发展概述

以EPCOS生产的声表面波(SAW)芯片级封装和晶圆级封装为例,介绍了声表面波器件小型化发展的趋势.着重介绍了声表器件芯片级封装技术发展的各个阶段器件的结构特点.详述采用倒装、贴膜和晶圆键合技术将声表面波器件的尺寸减至最小及后续声表面波器件组件化封装的趋势.     

甚高频高性能SAW滤波器

对甚高频（ＵＨＦ）高性能ＳＡＷ滤波器干扰模式采用了一种新的处理方法,即采用梯形ＳＡＷ单元网络与微带组合电路构成ＳＡＷ滤波器,用微带电路对干扰模式进行抑制。设计过程简洁,可采用成熟的ＳＡＷ单元电极和叉指参数进行计算机模拟,且当所设计的滤波器通带频率和带宽变化时,参数调整方便。并成功地用于９１４ＭＨｚ,带宽１７ＭＨｚ滤波器的设计。     

Surface Acoustic Waves in Reverse-Biased AlGaN/GaN Heterostructures

Properties of surface acoustic waves (SAWs) in reverse-biased AlGaN/GaN heterostructures on (0001) sapphire substrates were studied by examining the characteristics of SAW filters composed of interdigital Schottky and ohmic contacts. The fundamental and higher frequency SAW signals in measured -parameters were attributed to Rayleigh and Sezawa modes, respectively. The onsets of the SAW signals, which were close to the threshold voltage of HEMTs in the vicinities of the respective filters, changed in response to the spatial variation of the threshold voltage. The onset of Sezawa mode was deeper than that of Rayleigh mode, and the difference in onset was larger for longer SAW wavelengths. These results are possibly explained by the change of the input capacitance of interdigital transducers due to the reverse-bias voltages or by the difference in the distribution of SAW energy between the two modes.     

Thermosonic flip-chip bonding for SAW filter

A flip-chip bonding (FCB) method suitable for the surface acoustic wave (SAW) filter was developed. In this method, the gold-ball bumps formed on the chip are directly bonded onto the ceramic substrate by thermosonic bonding. After FCB, they are sealed with a cap without using underfill resin. To obtain high bond strength, characteristic properties of the substrate electrode and the ball bump, were optimized. Furthermore, bondability has been improved by adopting a ramp-up loading profile. The reliability test was carried out with 6-pin SAW chips, and we confirmed the sufficient reliability of bonds.     

An accommodative approach designed for TCP gold-to-gold inner lead bonding

This paper proposes an approach that resolves the tradeoff between bond pad crack, the passivation crack, and lead lift failure modes in gold-to-gold inner lead bonding. The bonding head temperature, stage temperature, and bonding force are addressed as three critical recipes. The proposed scenario determines the bonding head temperature according to the maximum compensation flatness, followed by the corresponding stage temperature and required bonding force in sequence. The relevant gold bump hardness, chip warpage, and flatness variation in the bonding tool were evaluated using the finite-element method. The corresponding bonding force was determined using semianalytical equations with empirical factors. A gate driver IC with 280 I/O pins was adopted to conduct the experimental verification in the engineering pilot run. With the optimal recipes, the obtained results demonstrated success in diminishing these three failure modes. The feasibility of proposed approach was verified experimentally.     

半导体器件金铝键合的寿命研究

金铝键合失效是MOSFET器件常见的失效模式之一,主要是由于金属间化合物的生成,影响了金铝键合的接触电性能,从而导致键合强度下降,接触电阻升高。针对这种失效模式,进行了三种不同高温条件下的加速寿命试验,并对这三种试验的器件进行金铝键合现象观察,对目前工艺水平下的金铝键合寿命进行了评估。     

铜丝键合在实际应用中的失效分析

研究并总结了铜丝键合塑封器件在实际应用环境中工作时发生的几种不同失效模式和失效机理,包括常见封装类型电路的失效,这些封装类型占据绝大部分铜丝键合的市场比例。和传统的实验室可靠性测试相比,实际应用中的铜丝失效能够全面暴露潜在可靠性问题和薄弱点,因为实际应用环境存在更多不可控因素。实际应用时的失效或退化机理主要包括:外键合点氯腐蚀、金属间化合物氯腐蚀、电偶腐蚀、键合弹坑、封装缺陷五种类型。对实际应用中的数据和分析为进一步改善铜丝键合可靠性、提高器件稳定性提供了依据。     

CSP键合金丝热应力分析

对CSP键合金丝的热可靠性进行了研究.运用数值分析方法,采用有限元软件ANSYS 8.0,分析了在热循环载荷条件下键合金丝的热应力,以及键合金丝可能出现的失效模式.