微电子封装组件热应变的云纹干涉法研究

本文提出云纹高频试件栅高温复制组件工艺,并应用于电子封装组件125℃～200℃,热应变的云纹干涉法测量,得到了封装组件表面在高温下的热膨胀系数,本云纹特点是灵敏度高,可全场测量,适用于电子封装组件热变形失效分析.     

高分辨率电镜微米云纹法及其应用

文中就云纹干涉法,电子束云纹法,原子力云纹法,扫描电镜云纹法,聚焦离子束云纹测量微区变形的原理和适用性进行了讨论.应用1200线/毫米的云纹光栅并结合云纹干涉法,电子束云纹法,原子力云纹法,扫描电镜云纹法测量QFP和BGA型电子封装组件的热变形.提出一种新型聚焦离子束云纹法,在MEMS结构上制栅形成FIB扫描云纹,成功的实验结果表明这种方法的可行性.     

电子封装组件热变形的实时观测

本文利用云纹干涉法,首次实时的对新型电子封装组件BGA在22℃至110℃温度载荷下的热变形进行了研究.研究表明对焊点截面的实时观测结果和试件的实际变形情况是完全吻合的.该结论为以后通过云纹干涉法高温实时观测技术进一步对焊点的热变形进行实时测量和研究铺平了道路.     

光学方法在微电子封装中的应用

热应力分析在微电子封装的设计和制造中是非常重要的一环. 影响微电子封装可靠性的因素包括封装结构中的温度分布、热致变形和关键界面上的层间粘结强度. 在微电子封装热应力分析和可靠性评估中,实验力学起着重要的作用. 凭借其内在的并行处理能力, 实验力学中的光学方法可以提供现场的、具有各种敏感度和解析度的全场位移测量,因而它也被广泛地用于微电子封装领域. 本文讨论了光学方法在微电子封装热应力分析中的应用,并举实例来说明光学方法是如何地被用于微电子封装技术的研发以及考核验收.     

CCD云纹方法的光学放大作用分析及其在干涉测量中的应用

几何云纹由于对栅线变形具有光学放大作用,常被用于高密度栅线的微小变形测量。但是其需要分别设置参考栅和试件栅,实验布置复杂。当使用数字相机直接拍摄试件栅时也会形成与几何云纹相似的CCD云纹,但是基于此原理发展的变形分析方法是否可以应用于高密度栅线变形分析还缺乏相关的研究。本文基于CCD云纹的形成机理和周期公式,分析并确认了其与几何云纹一样具有光学放大作用,因此可以将其应用于高密度栅线/干涉条纹的解析。利用此优势,实现了对高密度干涉条纹间距的解析,实现了两个相干点光源距离和迈克尔逊干涉实验转动角度的精密测量。本研究为干涉实验中高密度条纹分析提供了一种新的手段,可以解决实验中条纹过密无法解析的问题。     

云纹干涉法现场测量中的变形试件栅复制技术

本文研究了云纹干涉法的现场测量技术.该方法在现场测量过程中复制变形的试件栅.试件栅上保留了载荷引起的变形信息,通过云纹干涉法可以得到这些变形信息.该方法不但具有云纹干涉法的所有优点,并且使云纹干涉法可以在光学实验室以外场合中应用.     

显微云纹技术在微电子器件力学测量中的应用

电子工业的不断发展促进了电子器件的微小型化,作为新型产品设计基础的微电子器件可靠 性分析成为人们非常关注的问题. 力学参数的测量可以为可靠性评价提供有价值的实验依据. 概括总结了显微云纹技术的发展,主要介绍了云纹干涉法和扫描显微镜云纹方法及其在 微电子器件全场变形场测量中的应用.     

云纹干涉反转倍增法及其在微电子组件变形场测量中应用

本文提出并介绍了云纹干涉反转倍增法，该方法将光学载波、反转剪切、富立叶变换倍增技术巧妙地结合于云纹干涉光路中。利用载波频率，把带载波的云纹干涉变形图在富立叶变换系统中进行条纹倍增，而试样变形信息也倍增了相同倍数，将云纹干涉的测量灵敏度又提高了一个数量级。在实验中实现了１６倍倍增，即位移测量灵敏度由０．４μｍ提高到０．０２５μｍ（虚栅频率１／２４００）。将这一方法用于测量热载下金属Ｎｉ膜／ＺｒＯ２陶瓷基界面裂纹尖端面内位移场，分析裂尖位移奇异性。实验表明：热载作用下，膜／基组件界面裂纹尖端的位移奇异性具有指数奇异特性，其奇异性指数与膜／基材料，界面层特性等有关     

光学方法在微电子封装中的应用

热应力分析在微电子封装的设计和制造中是非常重要的一环。影响微电子封装可靠性的因素包括封装结构中的温度分布、热致变形和关键界面上的层间粘结强度。在微电子封装热应力分析和可靠性评估中，实验力学起着重要的作用。凭借其内在的并行处理能力，实验力学中的光学方法可以提供现场的、具有各种敏感度和解析度的全场位移测量，因而它也被广泛地用于微电子封装领域。本文讨论了光学方法在微电子封装热应力分析中的应用，并举实例来说明光学方法是如何地被用于微电子封装技术的研发以及考核验收。     

光学方法在微电子封装中的应用(英文)

热应力分析在微电子封装的设计和制造中是非常重要的一环。影响微电子封装可靠性的因素包括封装结构中的温度分布、热致变形和关键界面上的层间粘结强度。在微电子封装热应力分析和可靠性评估中,实验力学起着重要的作用。凭借其内在的并行处理能力,实验力学中的光学方法可以提供现场的、具有各种敏感度和解析度的全场位移测量,因而它也被广泛地用于微电子封装领域。本文讨论了光学方法在微电子封装热应力分析中的应用,并举实例来说明光学方法是如何地被用于微电子封装技术的研发以及考核验收。     

Study of thermal deformation of microelectronics packaging product by interferometric technique

In this paper, the out-of-plane deformation of silicon surface of Direct Chip Attachment (DCA) assembly, under thermal loading, was measured in real-time by Twyman/Green interferometry. The contour maps of the out-of-plane displacement fields of silicon surface under thermal loading and cycling of various temperature were obtained. Experimental results show that the relation between the out-of-plane displacement and temperature is nonlinear and varies with temperature cycling, due to nonlinear mechanical behavior of the materials used in electronic packaging. A comparison of the out-of-plane displacement fields of silicon surface measured by T/G interferometry in real-time and replicating technique of high temperature specimen grating of moire interferometry was made.     

Three-dimensional thermal deformations observed in SMT assembly during power cycling

The three-dimensional displacement fields of thermal-force coupling fatigue in a surface mounted plastic-quad-flat-pack (PQFP) assembly during power cycling by using the combination of holographic interferometry and high sensitivity moire interferometry is presented in this paper. Detailed in-plane and out-of-plane whole-field displacement data of the top and bottom ends of gull wing leads and their distributions along the edge of PQFP are provided. It was found that the maximum deformations of gull wing leads occur at the four corners of PQFP. The result presented herein should be useful in the evaluation of thermal fatigue damage mechanism of surface mount assemblies.     

Thermal expansion of copper-carbon fiber composites

The thermal expansion data are obtained for carbon fiber copper matrix composites prepared from variously arranged crossed ply unidirectional monolayers and copper foils. Four types of specimens are made with different thickness of monolayers and copper foils and constant carbon fiber content. The initial thermal treatment of all specimens was the same. After being cooled from the bonding temperature, they were cycled up to 673 K three times. Due to this treatment the cracks were created in the monolayers. The specimens were additionally cycled between the temperature of 293 K to 623 K and coefficient of thermal expansion calculated from the linear slope for lower temperatures was about 10⁻⁵ m/m/K and decreased to zero at 600 K due to the very low coefficient of thermal expansion of the carbon fibers. Thermal expansion led to large hysteresis by plastic flow of the copper matrix. The hysteresis loops after additional cycling did not change. No other cracks were observed by optical microscopy.     

基于内聚力模型法PBGA封装焊点/IMC界面的分层开裂研究

塑料球栅阵列封装PBGA的可靠性分析中,考虑封装过程中SnAgCu焊料与铜焊盘界面间产生的金属间化合物（Intermetallic compound,IMC）的影响,并引入内聚力模型（Cohesive zone model, CZM）,利用ANSYS对热循环作用下焊点/IMC界面的脱层开裂情况进行研究。结果表明：热循环作用下,在封装器件中焊点承受较大的应力应变,且远离中心的外侧焊点具有比内侧焊点更大的应力应变。IMC的存在极大的降低了焊点的可靠性。界面分层最先发生在最外侧的IMC/焊点界面的两端,随着热循环次数的增加,分层逐渐沿着界面两端向里扩展。在热循环的前几个阶段,各个界面的最大损伤值增大较快,随着热循环的继续加载,界面最大损伤值逐渐趋于稳定。整个过程中四号焊点界面的损伤值始终最大。     

Creep and thermal cycling fixture design for metal matrix composites

A creep-thermal cycling system with a constant stress cam has been designed to be inexpensive and easily fabricated in order to identify the creep and thermal-cycling damage mechanisms in metal-matrix composites (MMCs) with high ductility. The current system can be modified to be a stress thermal cycling (or fatigue) system.     

冷热循环处理对Fe基块体非晶合金摩擦磨损性能的影响

本文中采用电弧熔炼和感应熔炼后喷铸的方法制备了厚度为4 mm的Fe基块体非晶合金.通过对Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂块体非晶合金进行30次和60次冷热循环处理,并在往复式摩擦磨损条件下,研究冷热循环工艺对其摩擦磨损性能的影响.结果表明：冷热循环处理没有显著改变铁基非晶合金的非晶态结构. 30次冷热循环处理后,Fe基块体非晶合金发生了明显的软化,平均硬度由铸态的16.06 GPa降为14.06 GPa,平均弹性模量由241 GPa降为216 GPa.随着冷热循环次数和载荷的增加,非晶合金的平均摩擦系数和磨损率先减小后增大.冷热循环处理有利于降低非晶合金的平均摩擦系数和磨损量.当冷热循环次数为30次、载荷为30 N时,铁基非晶的摩擦系数由0.77降至0.72,表现出最小的摩擦系数,同时磨损率降低13.3%,表现出最小的磨损率[1.04×10^-6 mm³/(m·N)].铸态Fe基块...     

Quick assessment methodology for reliability of solder joints in ball grid array (BGA) assembly—Part II: Reliability experiment and numerical simulation

In the present study, a facility, i.e., a mechanical deflection system (MDS), was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly. It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days, but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments, the acceleration factors (AF) were obtained for different reliability testing conditions. Furthermore, by using the creep constitutive relation and fatigue life model developed in part I, a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS. As a result, a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly. The project supported by the National Natural Science Foundation of China (59705008)     

Whole-field residual stress measurement in rail using moiré interferometry and twyman/green interferometry via thermal annealing

A novel whole-field residual stress measurement technique is developed using moiré interferometry and Twyman/Green interferometry coupled with thermal annealing. The technique is successfully applied to residual stress measurement in rail. In the measurement, a high temperature resistant 1200-lines/mm cross grating is made on a rail transverse slice surface. The whole-field residual stress relief is achieved by thermal annealing. Moiré interferometry and Twyman/Green interferometry are employed to obtain the in-plane and out-of-plane deformations generated by the residual stress relaxation. The whole-field strain redistribution due to the residual stress relief is calculated, and the whole-field residual stress distribution, including the possible stress concentration, is then obtained. Because of the three-dimensional nature of the residual stress relaxation and the measurement, the three-dimensional residual stress reconstruction sometimes becomes possible based on some plausible assumptions. In this paper, the principle of the experimental theory, technique and procedures are described. Three-dimensional residual stress reconstruction in a rail using a transverse slice is shown. Its comparison to the hole-drilling method with moiré interferometry is also presented.     

Experimental study of enhanced heat transfer by addition of CuO nanoparticle

An energy storage system has been designed to study the thermal characteristics of paraffin wax with an embedded nano size copper oxide (CuO) particle. This paper presents studies conducted on phase transition times, heat fraction as well as heat transfer characteristics of paraffin wax as phase change material (PCM) embedded with CuO nanoparticles. 40?nm mean size CuO particles of 2, 5 and 10% by weight were dispersed in PCM for this study. Experiments were performed on a heat exchanger with 1.5–10?l/min of heat transfer fluid (HTF) flow. Time-based variations of the temperature distributions are revealed from the results of observations of melting and solidification curves. The results strongly suggested that the thermal conductivity enhances 6, 6.7 and 7.8% in liquid state and in dynamic viscosity it enhances by 5, 14 and 30% with increasing mass fraction of the CNEPs. The thermal conductivity ratio of the composites can be augmented by a factor up to 1.3. The heat transfer coefficient during solidification increased about 78% for the maximum flow rate. The analysis of experimental results reveals that the addition of copper oxide nanoparticles to the paraffin wax enhances both the conduction and natural convection very effectively in composites and in paraffin wax. The paraffin wax-based composites have great potential for energy storage applications like industrial waste heat recovery, solar thermal applications and solar based dynamic space power generation with optimal fraction of copper oxide nanoparticles.