基于一阶和二阶聚合通道特征的实时行人检测

为了同时改善实时行人检测的误检率和检测速度,文中引入了二阶聚合通道特征(SOACF)来提高行人检测算法的性能,该算法主要基于图像中的一阶信息聚合通道特征(ACF)检测器,互补了ACF与SOACF的性能,并设计开发了一种加权非最大抑制合并算法。与ACF检测器相比,该合并检测器不仅在INRIA,Caltech和KITTI行人数据集上表现良好,而且在Caltech和KITTI数据集上的误检率分别降低了4%和2%,检测速度比基于ACF的CheckerBoards检测器快了近100倍。     

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。     

应用于平板显示器封装的ACF新进展

随着平板显示器大型化、薄型化、高分辨率的发展趋势,对平板显示器封装技术提出了更高的要求.ACF符合电子线路封装精细化、集成化的发展要求,目前已广泛应用于平板显示器(例如LCD)的封装领域.综述了ACF应用于平板显示器封装的主要形式如TCP、COF、COG,分析了各种不同封装形式对ACF提出的不同性能要求,以及为了满足这些要求对ACF中导电粒子的大小、含量、硬度以及ACF中使用树脂的种类等方面进行结构性能改进的最新进展.     

CO_2激光引发甲基丙烯酸甲酯聚合的研究

本文叙述甲基丙烯酸甲酯单体在CO_2激光辐照下的聚合行为,并用红外光谱仪和高压液相色谱仪对聚合产物进行了分析,结果表明,不同的CO_2激光辐照频率,甲基丙烯酸甲酯能按自由基型或阴离子型机理进行聚合。     

ACF互联可靠性影响因素的研究进展

总结了材料、芯片结构和环境因素等对异向导电胶膜(Anisotropic Conductive Film;ACF)互联可靠性的影响。文献表明,ACF基体树脂的吸湿膨胀系数、粘结强度及玻璃转化温度严重影响组装产品的互联可靠性,而导电粒子的导电性、芯片的结构和焊盘的表面处理方式等对可靠性也有较大影响。文献中的可靠性试验表明,在上面提到的因素中,湿气是影响器件中ACF可靠性的主要因素。     

以含氟自由基引发聚合MMA塑料光纤

本文介绍了以含氟自由基作为引发剂，引发聚合甲基丙烯酸甲酯，并以此为纤芯材料制做塑料光纤。并从实验和理论上讨论了含氟自由基一一般引发剂引发聚合的聚甲基丙烯酸甲酯塑料光纤纤芯在化学结构上光学衰减的差异。     

基于增强聚合通道特征的实时行人重识别北大核心CSCD

由于目标姿态、摄像头角度、光线条件等因素的影响,行人重识别仍然是一个具有挑战性的问题。目前大多数方法主要注重提高重识别精度,对实时性考虑较少。因此,本文提出了一种基于增强聚合通道特征(ACF)的实时行人重识别算法。利用ACF对行人进行检测,并在此基础上,结合直方图特征和纹理特征构成增强ACF,作为行人重识别的特征描述子。利用测度学习方法对重识别模型进行训练。在4个数据集上的实验结果表明,与传统的重识别特征相比,提出的特征描述子逼近最好的重识别准确率,并且具有更快的计算速度。整个行人检测与重识别系统的运行速度达到10 frame·s^(-1)以上,基本可以满足实时行人重识别的需求。     

组装工艺对ACF互连性能的影响

总结了异向导电胶膜(ACF)的组装工艺对ACF导电性能的影响.文献表明在ACF组装过程中,组装的温度、压头的压力和加热时间对ACF的固化程度有直接影响,进而影响到ACF互连的力学性能、电学性能和可靠性.合适的组装温度在180～200 ℃;不同的组装形式均有其最佳的组装压力;ACF胶的互连电阻在87%固化程度时最小;固化程度小于50%,出现短路的概率较大,达到25%;随着偏移程度的增加,ACF的互连电阻增加,导电粒子的形状对偏移产生的绝缘电阻影响更大.     

ACF在LCD中的应用与发展

该文通过对ACF和ACF在FPC应用的研究,着重论述ACF与FPC在液晶显示器LCD的应用与发展。     

光催化纳米TiO2/ACF复合滤料净化空气性能的试验研究及环境影响因素分析

通过光催化降解甲醛的静态和动态试验表明,TiO2/ACF复合滤料对甲醛的净化率均比ACF滤料净化效果好,对光催化纳米TiO2与ACF协同作用提高净化率作了分析,并阐述了环境因素对净化效果的影响。     

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.     

Effects of thermoplastic resin content of anisotropic conductive films on the pressure cooker test reliability of anisotropic conductive film flip-chip assembly

The flip-chip technology using anisotropic conductive films (ACFs) is gaining growing interest due to its technical advantages such as environmentally friendly, simpler, and lower cost processes. Electrical performances and reliability of ACF flip-chip assembly depend on thermomechanical properties of ACF polymer resins. In this paper, the changes in ACF resin morphology due to the phase separation of thermoplastics, and subsequent changes of physical and mechanical properties were investigated as a function of thermoplastic contents of ACF formulation. Furthermore, the pressure cooker test (PCT) reliability of ACF flip-chip assemblies with various thermoplastic contents was also investigated. As thermoplastic contents increased, coefficient of thermal expansion (CTE) of ACFs increased, and elastic modulus (E′) of ACFs decreased. In contrast, water absorption rate decreased as thermoplastic content increased. As a result, PCT reliability of ACF flip-chip assembly was improved adding up to 50 wt.% content of thermoplastic. An erratum to this article is available at .     

Highly reliable flip-chip-on-flex package using multilayered anisotropic conductive film

Anisotropic conductive film (ACF) has been used as interconnect material for flat-panel display module packages, such as liquid crystal displays (LCDs) in the technologies of tape automated bonding (TAB), chip-on-glass (COG), chip-on-film (COF), and chip-on-board (COB). Among them, COF is a relatively new technology after TAB and COG bonding, and its requirement for ACF becomes more stringent because of the need of high adhesion and fine-pitch interconnection. To meet these demands, strong interfacial adhesion between the ACF, substrate, and chip is a major issue. We have developed a multilayered ACF that has functional layers on both sides of a conventional ACF layer to improve the wetting properties of the resin on two-layer flex for better interface adhesion and to control the flow of conductive particles during thermocompression bonding and the resulting reliability of the interconnection using ACF. To investigate the enhancement of electrical properties and reliability of multilayered ACF in COF assemblies, we evaluated the performance in contact resistance and adhesion strength of a multilayered ACF and single-layered ACF under various environmental tests, such as a thermal cycling test (−55°C/+160°C, 1,000 cycles), a high-temperature humidity test (85°C/85% RH, 1,000 h), and a high-temperature storage test (150°C, 1,000 h). The contact resistance of the multilayered ACF joint was in an acceptable range of around a 10% increase of the initial value during the 85°C/85% RH test compared with the single-layered ACF because of the stronger moisture resistance of the multilayered ACF and flex substrate. The multilayered ACF has better adhesion properties compared with the conventional single-layered ACF during the 85°C/85% RH test because of the enhancement of the wetting to the surface of the polymide (PI) flex substrate with an adhesion-promoting nonconductive film (NCF) layer of multilayered ACF. The new ACF of the multilayered structure was successfully demonstrated in a fine-pitch COF module with a two-layer flex substrate.     

Adhesion strength and contact resistance of flip chip on flex packages––effect of curing degree of anisotropic conductive film

The use of anisotropic conductive adhesives film (ACF) as an interconnect materials for flip-chip joining technique is increasingly becoming a vital part of the electronics industry. Therefore, the performances of the ACF joint turn into an important issue and depend mostly on the curing condition of the ACF matrix. ACF is a thermosetting epoxy matrix impregnated with small amount of electrically conductive particles. During component assembly, the epoxy resin is cured to provide mechanical connection and the conducting medium provides electrical connection in the z-direction. Therefore, the cure process is critical to develop the ultimate electrical and mechanical properties of ACF. The purpose of the present work is to investigate optimum curing conditions to achieve the best performance of ACF joints. Differential scanning calorimeter was used to measure the curing degree. Adhesion strength was evaluated by 90° peeling test. The contact resistance has also been studied as a function of bonding temperature and curing degree. Results show a strong dependence of curing condition on the electrical and mechanical performances. Adhesion strength increases exponentially with the curing degree. Whereas the contact resistance decreases with the curing degree and achieve the minimum value at 87% of curing. Co-relation of the curing degree of the ACF was also studied through the detailed investigation of the fracture surfaces under scanning electron microscopy.     

Curing kinetics of anisotropic conductive adhesive film

Polymer-based conductive-adhesive materials have become widely used in many electronic packaging interconnect applications, such as chip-on-glass, chip-on-flex, etc. Among all the conductive-adhesive materials, anisotropic conductive adhesive film (ACF) is an attractive interconnect material because of its fine pitch capability. Anisotropic conductive-adhesive film is a thermosetting, epoxy matrix impregnated with a small amount of electrically conductive particles. During component assembly, the epoxy resin is cured to provide mechanical connection, and the conducting medium provides electrical connection in the z direction. The thermal cure process is critical to develop the ultimate electrical and mechanical properties of the ACF. In this paper, the curing reaction of ACF was studied with a differential scanning calorimeter (DSC) under isothermal conditions in the range of 120–180°C. An autocatalyzed kinetic model was used to describe the curing reaction. The rate constant and the reaction orders were determined and used to predict the progress of the curing reaction. A good agreement is found between the proposed kinetic model and the experimental reaction-rate data. The reaction-rate constants were correlated with the isothermal temperature by the Arrhenius equation. The glass-transition temperature also has been studied as a function of cure degree and moisture absorption.     

ACF在LCD中的应用与发展

在瞬息万变的信息时代,LCD已经成为人机信息交换不可缺少的产品。影响其结构（降低厚度）及技术（提高精密度）的关键材料是ACF与FPC。通过对ACF和ACF在FPC应用的研究,着重论述ACF与FPC在液晶显示器LCD的应用与发展。     

Research on the contact resistance,reliability, and degradation mechanisms of anisotropically conductive film interconnection for flip-chip-on-flex applications

Although there have been many years of development, the degradation of the electrical performance of anisotropically conductive adhesive or film (ACA or ACF) interconnection for flip-chip assembly is still a critical drawback despite wide application. In-depth study about the reliability and degradation mechanism of ACF interconnection is necessary. In this paper, the initial contact resistance, electrical performance after reliability tests, and degradation mechanisms of ACF interconnection for flip-chip-on-flex (FCOF) assembly were studied using very-low-height Ni and Au-coated Ni-bumped chips. The combination of ACF and very-low-height bumped chips was considered because it has potential for very low cost and ultrafine pitch interconnection. Contact resistance changes were monitored during reliability tests, such as high humidity and temperature and thermal cycling. The high, initial contact resistance resulted from a thin oxide layer on the surface of the bumps. The reliability results showed that the degradation of electrical performance was mainly related to the oxide formation on the surface of deformed particles with non-noble metal coating, the severe metal oxidation on the conductive surface of bumps, and coefficient of thermal expansion (CTE) mismatch between the ACF adhesive and the contact conductive-surface metallization. Some methods for reducing initial contact resistance and improving ACF interconnection reliability were suggested. The suggestions include the removal of the oxide layer and an increase of the Au-coating film to improve conductive-surface quality, appropriate choice of conductive particle, and further development of better polymeric adhesives with low CTE and high electrical performance.