导电胶在固化中电阻的自动测量采集系统设计研究

导电胶作为元铅连接材料的一种，近年来在微电子封装、组装中越来越受重视。本文简单介绍了导电胶的分类、组成，重点介绍一种新的导电胶电阻的测试方法和导电胶在固化过程中电阻的自动测量采集系统设计，通过最后选用的导电胶实验证明本文设计的系统完全能够满足导电胶电阻的测试要求。     

导电胶研究现状及其在LED产业中的应用

伴随中国战略性新兴LED产业的迅猛发展,LED芯片与基板之间的连接材料—导电胶,也成为了当前学术界和产业界的研究热点之一。分别从导电胶主要成分方面阐述了导电胶近年来的研究成果,为导电胶研发过程中的成分选择及优化处理提供参考。并展望了今后导电胶的发展趋势和应用前景。     

各向异性导电胶互连技术的研究进展

随着微电子封装技术的发展,各向异性导电胶作为一种绿色的连接材料,广泛应用于电子产品中。文中主要介绍各向异性导电胶互连器件的粘接原理和影响其可靠性的各种因素,如粘接工艺参数、外界环境的干扰、各向异性导电胶的物理特性等。     

精细电路连接用紫外光固化各向异性导电胶

为适应高密度超细线路连接的需要,研究了紫外光固化各向异性导电胶。得到了可以用UV(紫外光)有效固化的各向异性导电胶(ACA)。通过对固化过程和应用于氧化铟锡连接实验的分析,研究了各组分在体系中的作用和添加量对导电胶的连接性能和导电性能的影响。结果表明,紫外光固化各向异性导电胶为液晶显示(LCD)和电致发光显示(ELD)技术提供了一种新的连接方式。     

金属粉末-聚合物复合导电胶研究进展

随着电子封装工艺的发展,越来越多的人们致力于研发更高性能、环境友好的新连接材料,以聚合物为基体的复合导电胶在电子封装领域的应用也由此越来越广泛。文章介绍了导电胶的分类和组成,以及改善导电胶性能的方法与技术,从宏观和微观角度对导电机理进行了探讨并对研究前景做了展望。     

CLD——3铜粉导电胶试验

导电胶粘剂在电子工业生产中已得到广泛的应用。但目前国内所使用的导电胶都以银粉作为导电填料。银粉为填料的导电胶导电性能优异,化学稳定性强,有较好的耐久性。但此种导电胶有一个致命的问题——就是存在“银迁移”现象,即如文献指出的“在电压差加高潮湿度的一定条件下”,银将跨过介质材料,“迁移”形成导电线路短路,造成导电连接失败。另外银粉价格昂贵,使胶的成本增高。国内外对此进行了广泛的研究,提出了许多的专利和方法。如研     

诺基亚正常使用时花屏

故障现象:一部诺基亚8850型手机,正常使用时忽然花屏。故障分析:由于诺基亚8850显示屏是通过导电胶与机身相连,时间一长,会因为导电胶变质或连接变松导致该     

高热导率纳米银胶的可靠性研究

对无压力低温固化纳米银胶的连接强度、导热性和导电性及其可靠性进行了研究,并与Au80Sn20焊料及普通导电胶进行对比。结果表明:纳米银胶连接强度高,平均剪切强度可达28 MPa;导热性能优异,连接层热阻接近Au80Sn20焊料层热阻;在严酷的热应力和机械应力试验后,其连接强度、导热性和导电性保持稳定,没有退化现象产生。因此,无压力低温固化的纳米银胶作为高功率器件连接材料具备较高的可靠性。     

半导体集成电路封装用环氧树导电胶概论

简要叙述用于半导体集成电路封装芯片粘接用材料---环氧树脂导电胶组成成分、特性,重点介绍了环氧树脂导电胶在使用过程中要考虑的因素。     

导电胶性能对器件分层的影响

近年来客户对器件可靠性要求越来越高,而分层对可靠性的影响至关重要。跟分层密切相关的两种主要封装材料分别为塑封料和导电胶,文中重点对LQFP类导电胶进行性能比较、分层试验和相关性分析,明确了导电胶的相关性能对器件分层的影响程度,从而选择合适的导电胶来改善和提高器件的可靠性。     

正弦激励下的导电胶非线性测试评价方法

目前由于电子产品中器件非线性引起的电磁可靠性问题变得越来越严重,为了准确评估不同导电胶产品在正弦信号激励下非线性特性的优劣,设计了一套基于窄带滤波器和微带线的简单且行之有效的非线性特性测试方法,在测试中使用滤波器排除测试系统固有的三次谐波。由于非线性效应会产生电压、电流的高次谐波成分,该方法以三次谐波的功率作为导电胶的非线性特性的衡量指标,通过测量不同导电胶的三次谐波功率来完成非线性特性的对比测试,为导电胶的测试评价及设计研发提供技术支撑。     

Electrically Conductive Carbon-Nanotube Framework Materials

Semiconductors - Conductive materials based on carbon and its modifications are most promising for creating biointerfaces. Such materials can be used for the targeted stimulation of cells and...     

高分子聚合物超电容器研究

超电容器具有能量密度高,循环寿命长,可大功率充放电等特性,应用前景诱人。导电性聚合物由于可取得较高的容量和价格低廉,是合适的超电容器电极材料。采用不同掺杂方式的导电性聚合物(N型或P型)作为电极材料使相应的超电容器分为三种类型,各具有不同的工作电压及容量特性。笔者综述了聚合物超电容器的工作原理和最新研究进展。     

A study of lubricants on silver flakes for microelectronicsconductive adhesives

Conductive adhesives are composites of polymer matrixes and metal fillers (conductive elements). Silver (Ag) flakes are widely used as fillers for electrically conductive adhesives (ECAs). Generally, there is a thin layer of organic lubricant coated on the commercial Ag flake surface. This lubricant layer is needed for eliminating the Ag particle agglomeration while dispersing the Ag filler into the polymeric resin. Therefore the lubricant influences rheology, conductivity, and other properties of ECA's. The nature of the lubricant on a Ag flake and the interaction between the lubricant and the Ag flake surface were studied by diffuse reflectance infrared spectroscopy (DRIR). Thermal decomposition of the lubricant was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, the effects of some chemical compounds on lubricant removal and the enhancement of conductivity of the ECA were also investigated. It was found that 1) a chemical bonding was formed on the Ag flake surface between the lubricant and Ag; 2) the short chain acids replaced the long chain lubricants; 3) an ether and a poly(ethylene glycol) enhanced electrical conductivity by partially removing the Ag flake lubricants     

Highly Conductive,Flexible, Polyurethane‐Based Adhesives for Flexible and Printed Electronics

Flexible interconnects are one of the key elements in realizing next‐generation flexible electronics. While wire bonding interconnection materials are being deployed and discussed widely, adhesives to support flip‐chip and surface‐mount interconnections are less commonly used and reported. A polyurethane (PU)‐based electrically conductive adhesive (ECA) is developed to meet all the requirements of flexible interconnects, including an ultralow bulk resistivity of ≈1.0 × 10^?5 Ω cm that is maintained during bending, rolling, and compressing, good adhesion to various flexible substrates, and facile processing. The PU‐ECA enables various interconnection techniques in flexible and printed electronics: it can serve as a die‐attach material for flip‐chip, as vertical interconnect access (VIA)‐filling and polymer bump materials for 3D integration, and as a conductive paste for wearable radio‐frequency devices.     

High temperature reliability of electrically conductive adhesive attached temperature sensors on flexible polyimide substrates

The attachment and packaging of temperature sensors may be challenging due to their structure and materials. Sensing requires a structure which is open to the environment and the materials often differ from those used in silicon-based electronics. Thus, traditional attachment techniques and materials such as soldering may be inappropriate. Polymer-based electrically conductive adhesives (ECA) are an alternative. The operating environment of a sensor may, however, be very demanding. Very little research data is available on the use of ECAs in challenging conditions, thus restricting their use in many applications. This study tested the behaviour of temperature sensors attached with ECAs onto flexible polyimide (PI) substrates in thermal storage at 200 °C. More than 1000 h of testing without failures were conducted on the ECA sensor structures. Good high temperature reliability therefore seems to be possible with ECAs. However, the PI substrate was observed to be critical to reliability. An adhesive layer used in the PI substrate reacted at the test temperature and severe oxidation of the copper pads and reaction between the materials consequently destroyed the interconnection and caused failures.     

导电衬垫材料的研究与发展

导电衬垫材料是电子设备中应用最为广泛的一类屏蔽材料，在抑制电子设备缝隙电磁泄漏方面发挥了重要作用。文章结合作者的科研工作，对于衬垫材料的抑制机理、材料类型、屏蔽特性、屏效计算、应用技术、测试方法等关键技术进行了综述，并提出了将来研究发展的方向。     

Analysis of Enhanced Collision Avoidance Scheme Proposed for IEEE 802.11e-Enhanced Distributed Channel Access Protocol

In enhanced distributed channel access (EDCA) protocol, small contention window (CW) sizes are used for frequent channel access by high-priority traffic (such as voice). But these small CW sizes, which may be suboptimal for a given network scenario, can introduce more packet collisions, and thereby, reduce overall throughput. This paper proposes enhanced collision avoidance (ECA) scheme for AC_VO access category queues present in EDCA protocol. The proposed ECA scheme alleviates intensive collisions between AC_VO queues to improve voice throughput under the same suboptimal yet necessary (small size) CW restrictions. The proposed ECA scheme is studied in detail using Markov chain numerical analysis and simulations carried out in NS-2 network simulator. The performance of ECA scheme is compared with original (legacy) EDCA protocol in both voice and multimedia scenarios. Also mixed scenarios containing legacy EDCA and ECA stations are presented to study their coexistence. Comparisons reveal that ECA scheme improves voice throughput performance without seriously degrading the throughput of other traffic types.     

A spatio-temporal dipole simulation of gastrointestinal magnetic fields

We have developed a simulation of magnetic fields from gastrointestinal (GI) smooth muscle. Current sources are modeled as depolarization dipoles at the leading edge of the isopotential ring of electrical control activity (ECA) that is driven by coupled cells in the GI musculature. The dipole moment resulting from the known transmembrane potential distribution varies in frequency and phase depending on location in the GI tract. Magnetic fields in a homogeneous volume conductor are computed using the law of Biot-Savart and characterized by their spatial and temporal variation. The model predicts that the natural ECA frequency gradient may be detected by magnetic field detectors outside the abdomen. It also shows that propagation of the ECA in the gastric musculature results in propagating magnetic field patterns. Uncoupling of gastric smooth muscle cells disrupts the normal magnetic field propagation pattern. Intestinal ischemia, which has been experimentally characterized by lower-than-normal ECA frequencies, also produces external magnetic fields with lower ECA frequencies.     

Shielding Effectiveness Data on Commercial Thermoplastic Materials

Ten different commercially available conductive thermoplastic materials have been tested for near- and far-field shielding effectiveness (SE). Far-field SE was tested using a modified standard measurement technique to provide results comparable with the company-provided data. Further, housings of different thermoplastic materials were constructed and equipped with an electromagnetic interference (EMI) source to model a realistic near-field SE situation. The SE data up to 1 GHz is presented. Conductive thermoplastic materials with fillings of stainless steel fibers and nickel-coated carbon fibers were the two materials that offer the best far-field shielding performance. For the near-field shielding, two materials with filling of stainless steel fibers were the best performing ones. A thermoplastic with polycarbonate (PC) base and stainless steel content of 1.5 vol% showed the best combined far- and near-field shielding results