m值“复合”逻辑函数的Chrestenson循环谱、自相关函数及应用

该文利用反演公式求得了m值“复合”逻辑函数的Chrestenson循环谱的计算公式，并由此得到了m值“复合”逻辑函数的自相关函数的计算公式，进而运用这两个公式，给出了m值“复合”逻辑函数具备平衡性、相关免疫性的条件，并对m值“复合”逻辑函数的自相关函数及其性质进行了分析；此外该文还得到有限个m值“复合”逻辑函数的非零线性和函数的Chrestenson循环谱的计算公式。     

锁相环脉冲响应函数的测量和分析

本文基于实际存在的M序列的自相关函数,得到了用相关法求系统脉冲响应函数的基本公式。讨论了测量锁相环脉冲响应函数的方法,并给出了测量所用主要部件的数学模型。最后对实测曲线作了频谱分析。     

论复码的D变换正交展开及其应用

本文从基本逻辑函数的D变换展开出发,用严格的数学归纳法证明了任意的n元逻辑函数F的D变换均可表成2~n个函数分号的线性组合。进而证明了这2~n个函数分量均成了GF_2上n元逻辑函数空间的完备正交基。文中还给出这种D变换正交展开的其它表示形式。并初步讨论了n元逻辑函数的D变换正交展开的若干重要牲质。介绍求取这种D变换正交展开式的两种方法——卡诺图法和矩阵法。本文的后半部份探讨了这种D变换正交展开在伪随机复合码的归一化自相关函数和归一化功率谱密度函数研究中的应用,得出n元复码的归一化自相关函数和归一化功率谱密度函数的通用表达式。为了熟悉和应用本文导出的公式,文中还给出适当的工程计算实例。应用本文导出的公式来计算复码的自相关函数和功率谱密度函数只需进行一些极简单的算术运用,求出通用表达式中几个参数即可。     

k-阶旋转对称函数性质分析与轨道计数

研究了k-阶旋转对称函数的性质,证明了k-阶旋转对称函数的Walsh谱和自相关函数都满足k-阶的旋转对称。分析发现k-阶旋转对称函数的很多性质都可以利用其轨道来刻画,并给出了k-阶旋转对称函数的轨道中的长圈和短圈的计数公式。     

自动测试系统及智能测试技术讲座 第十四讲 智能测试技术(三)

数字信号处理是一门独立学课.本讲座只介绍其中最常用的一些处理方法.广义相关处理是指任意两个变量之间的相关性.一般相关处理都是指一个或两个变量在时间方面的相关性.关于这一点在本刊1984年刊登的微弱信号检测讲座中已介绍过,这里只列出它的有关公式,以便进一步推广到广义相关处理.九、广义相关处理对时间相关的函数主要是自相关函数及互相关函数.自相关函数     

一阶相关免疫函数计数下界的改进

本文构造了一大类相关免疫布尔函数，给出了一阶相关免疫函数个数的新的下界，从而大大改进了相关免疫函数的计数公式。     

利用随机信号处理理论研究频稳问题

本文根据随机信号处理理论,提出了利用随机信号处理模型(或系统)来分析频稳问题。文中导出了系统及子系统的单位冲击响应、传输函数、单位冲击响应的自相关函数、功率或能量传输函数;导出了系统各点随机信号的自协方差函数、功率谱密度函数;根据前两点还导出了几种主要随机信号谱型的N抽样方差必〈σ_y~2(N,T_0,T)〉的计算公式;导出了Allan方差的理论、工程计算及相对误差公式。 本文还指出了,文献[3,6,9～11]在计算闪烁相位噪声的Allan方差公式的不妥之处。     

散斑调制用于提高体全息相关器的识别率

体全息相关器能够进行快速的光学并行相关识别．但是在相关识别的过程中，页间串扰导致相关结果中旁瓣太多，影响了相关峰的判断，大大降低了相关器的识别准确率。为了抑制旁瓣．对传统的体全息相关公式中所产生串扰的因子进行了分析，引入了随机函数的自相关函数作为调制因子对公式进行修正．可以实现在水平方向和竖直方向同时抑制旁瓣．抑制效果与全息图的厚度无关。并提出在相关器的物光光路中物的前方放置随机相位器，实现对物函数的散斑调制。理论分析、数值计算及实验结果表明．该方法可以抑制旁瓣．突出相关峰．提高体全息相关器的识别准确率和通道密度。     

一阶相关免疫函数的计数

本文在文献「１」「２」的基础上研究了一阶相关免疫函数的计数问题,给出了非经的一介相关免疫函数计数的最新公式,从而也给出了一阶相关免疫函数计数的一个新的下界。     

关于本原M序列的自相关函数

本文研究了本原M序列的自相关性能,首次获得了部份自相关函数的通解。这些通解的作用在于无需给出序列,只要知道反馈函数就可以获得相应的自相关函数值,大大降低了自相关函数的计算量。此外,还给出了自相关函数C(#em/em#)(n#em/em# 2n-1)的取值范围。     

非相干散射雷达巴克码与交替码自相关函数计算方法研究

非相干散射雷达使用复杂的信号处理技术来获得多种高精度的电离层参数，自相关函数计算是其中的关键.文章详细推导了非相干散射雷达的模糊函数与自相关函数表达式，并针对常用的13位巴克码和16位交错码（alternating code，AC）的整数阶和分数阶进行了仿真与分析.研究发现:1）巴克码不适合计算非零时延处的自相关函数；2）AC码分数阶比整数阶有更多的时延点数，自相关函数计算更准确，同时功率谱谱宽增加.以上结果对提升我国电离层非相干散射探测与研究水平具有重要意义.     

Failure mechanism study of anisotropic conductive film (ACF) packages

Anisotropic conductive film (ACF) consists of an adhesive polymer matrix with dispersed conductive particles. In flip-chip technology, ACF has been used in place of solder and underfill for chip attachment to glass or organic substrates. The filler particles establish the electrical contacts between the interconnecting areas. ACF flip-chip bonding provides finer pitch, higher package density, reduced package size and improved lead-free compatibility. Nevertheless, the interconnection is different from traditional solder joints, the integrity and durability of the ACF interconnects have major concerns. Failures in anisotropic conductive film (ACF) parts have been reported after temperature cycling, moisture preconditioning and autoclave. The failures have not been well understood and have been attributed to a wide variety of causes. This paper investigates the failure mechanism of ACF using finite element simulation. From a failure-initiation point of view, the response of ACF packages to environmental (temperature and humidity) exposure is very different from standard underfilled packages. These differences cause the ACF package to fail in different ways from an underfilled package. Simulation results have shown that moisture-induced ACF swelling and delamination is the major cause of ACF failure. With moisture absorption, the loading condition at the interface is tensile-dominant, which corresponds to lower interface toughness (or fracture resistance). This condition is more prone to interface delamination. Therefore, the reliability of ACF packages is highly dependent on the ACF materials. The paper suggests a new approach toward material selection for reliable ACF packages. This approach has very good correlation with experimental results and reliability testing of various ACF materials.     

Fatigue life evaluation of anisotropic conductive adhesive film joints under mechanical and hygrothermal loads

The shear fatigue lives of Anisotropic Conductive Adhesive Film (ACF) joints were evaluated experimentally and theoretically under different testing conditions. The shear fatigue tests of ACF joints were performed with different loading amplitudes. It is found that the fatigue lives of ACF joints decrease with increasing loading amplitudes and Basquin’s equation is fit to predict the fatigue lives of ACF joints. Hygrothermal aging and thermal cycling tests were conducted to investigate the shear strength and lives of ACF joints. The results show that the shear strength and lives of ACF joints decrease with increasing hygrothermal aging time, however increase firstly and then decrease with increasing thermal cycling time. The fatigue life model considering aging damage is proposed and the predictions of the fatigue life agree with the experimental results at different aging time for ACF joints.     

Anisotropic Conductive Film Bonding by Making Use of a High-Power Diode Laser

Anisotropic conductive film (ACF) bonding between liquid crystal displays (LCDs) and driver integrated circuits (ICs) is one of the key technologies for developing high-resolution LCDs. The bonding pitch between LCD and tape carrier package (TCP), which influences the total reliability of LCD modules, depends on the characteristics and bonding conditions of ACF used. So, the bonding process between TCP and a glass panel with ACF using a high-power diode laser as a heat source for curing is preliminarily tested in this experiment. Also, laser transient thermal simulation was performed to analyze the thermal response of the assembly process for a package using ACF. The temperature on the ACF layer goes up to 180 degC (ACF curing temperature) within 1 s after exposure to laser light. This paper reports an effective bonding method using a diode laser, which accomplishes a fine-pitch ACF bonding and determines the optimum ACF bonding condition effectively     

环境对各向异性导电胶膜性能参数的影响

各向异性导电胶膜(ACF)的玻璃转化温度T_g是它的一个重要性能参数,用差示扫描热示计(DSC)分别测定商用各向异性导电胶膜固化前和固化后的玻璃转化温度,并确定不同的固化时间对它的玻璃转化温度的影响,以及高温高湿(85℃,85%RH)环境对它的玻璃转化温度影响,得到各向异性导电胶玻璃转化温度下降是其粘接强度下降的原因之一。     

Understanding of Delamination Mechanism of Anisotropic Conductive Film (ACF) Bonding in Thin Liquid Crystal Display (LCD) Module

The chip-on-glass (COG) technique using anisotropic conductive film (ACF) has been developed for liquid crystal display (LCD) panels with excellent resolution and high quality for several years. However, many serious manufacturability and reliability issues were observed from previous studies. In those, delamination occurring at the ACF interface is one of the common concerns. Few works presented analysis of delamination mechanism through the whole COG bonding process with the combination of LCD module scale and ACF interconnect scale. In this paper, the delamination mechanism of COG/ACF interconnection was studied by using finite element analysis. Equivalent block and global-local modeling methods were implemented with nonlinear elastic-plastic and sequential coupled thermal-mechanical analysis. The critical parameters of the COG bonding process and geometry of integrated circuit (IC) and glass were investigated to understand the mechanism of ACF delamination. It was found that the delamination could be reduced by decreasing the temperature difference between bonding head and glass substrate or using thin and short IC. The local model analysis revealed that the interface of glass/ACF epoxy encountered the higher stress than that in the interface of IC/ACF epoxy and had the higher possibility to delaminate. Therefore, increasing the bonding-strength between glass and ACF epoxy is the direction to reduce the probability of ACF delamination.     

Adhesion and Reliability of Anisotropic Conductive Films (ACFs) Joints on Organic Solderability Preservatives (OSPs) Metal Surface Finish

The effect of final metal finishes of Cu electrodes on the adhesion and reliability of anisotropic conductive film (ACF) joints was investigated. Two different metal surface finishes, electroless Ni/immersion Au (ENIG) and organic solderability preservatives (OSPs) coated on Cu, were selected in this study for ACF bonding. The adhesion strength of ACF/OSP joints was higher than that of ACF/bare Cu and ACF/ENIG joints. The fracture sites of the ACF/bare Cu and ACF/ENIG joints were ACF/metal interfaces, while those of ACF/OSP joints were inside the ACF. Transmission electron microscope (TEM) and Fourier-transform infrared (FT-IR) analyses showed that the OSP coating layer on the Cu electrodes reacted with the epoxy resin of the ACFs but still remained at the bonding interface. According to the in-depth X-ray photoelectron spectroscopy (XPS) analysis, additional C-N bonds formed after the OSP-epoxy reaction and the outermost nitrogen of the OSP layer participated in curing of the epoxy resin of the ACF. Therefore, the OSP layer acted as an adhesion promoter to ACFs. Furthermore, this role of the OSP layer enhanced the reliability of the ACF/OSP joints under high temperature and humid environments, as compared to the ACF/ENIG joints.     

ACF各向异性导电胶的工艺评价方法

ACF作为一种实装材料,可以方便地实现精细电极的导通连接。其原理是通过加热、加压、树脂受热固化、ACF中的导电粒子连接上下电极,从而实现电极固定和电极导通。实际上受ACF成份的影响,每种ACF的特性都不一样,而在生产应用中,温度、压力、时间、位置、辅助材料等因素又会对连接的效果产生影响。为了确保ACF适用于厂内的工艺,把ACF的应用风险降低。评价一种ACF的过程,通常分为单体评价、工艺评价和产品评价。文中将以屏侧ACF为例,讨论ACF工艺评价的方法。     

环境对各向异性导电胶膜性能参数的影响

各向异性导电胶膜(ACF)的玻璃转化温度Tg是它的一个重要性能参数,用差示扫描热示计(DSC)分别测定商用各向异性导电胶膜固化前和固化后的玻璃转化温度,并确定改变固化时间对它的玻璃转化温度的影响,以及高温高湿(85℃,85%RH)环境对它的玻璃转化温度的影响,得到各向异性导电胶玻璃转化温度下降是其粘接强度下降的原因之一。     

Effects of Anisotropic Conductive Film Viscosity on ACF Fillet Formation and Chip-On-Board Packages

In this paper, the effects of anisotropic conductive film (ACF) viscosity on ACF fillet formation and, ultimately, on the pressure cooker test (PCT) reliability of ACF flip chip assemblies were investigated. The ACF viscosity was controlled by varying the molecular weight of the epoxy materials. It was found that the ACF viscosity increased as the increase of molecular weight of the epoxy materials. However, there was little variation of the thermomechanical properties among the evaluated ACFs with different viscosites. Also, the results showed that the ACFs have no differences in moisture absorption rate, die adhesion strength, and degree-of-cure. In scanning electron microscopy images, the lower ACF viscosity resulted in the smoother ACF fillet shape and the higher fillet height. From the results of PCT, the ACF flip chip assembly with the smoother fillet shape showed better reliability in terms of contact resistance changes. After 130 h of PCT, the flip chip assembly with lower ACF viscosity also showed a lesser degree of delamination at the ACF/chip interface.