内层半固化片选择对PCB耐CAF性能的影响

阳极导电丝（CAF）是PCB业内近十年来较为热门的可靠性问题之一,当PCBA工作在高温高湿的环境下时,有可能产生沿玻璃纤维生长的阳极导电丝CAF。文章主要研究了PCB设计中的关键因素叠层设计对耐CAF性能的影响,通过分析不同半固化片的异同点,对比不同半固化片在玻纤裂纹和CAF失效寿命方面的差异。通过不同半固化片的CAF寿命数据,推算不同叠层设计的CAF寿命,为有较高cAF可靠性要求的产品研究提供了理论依据和试验基础。     

应用于刚挠印制板无铅工艺兼容的不流动性半固化片

当今电子产品的功能不断增加，随之而来的是对电子产品设计多样化的要求。正是由于这种需求，刚挠结合板以其巨大的技术进步和不断增加的需求而获得关注。这其中的不流动性半固化片是将刚性板与挠性板结合在一起的关键材料，它的主要功能是在刚性材料和挠性材料之间形成可靠性的粘接层，所以对该材料界面性质和功能进行研究。对于不流动性半固化片的应用来说是至关重要的。现在，一种新的基于酚醛固化树脂体系的不流动性半固化片已经被开发出来，这种新型材料显示了优异的耐热性和可靠性。经过热性能分析和热冲击测试，这种新型材料的性能比传统的DICY固化环氧树脂体系材料更加优越。     

半固化片浸渍加工技术的新进展

高密度互连印制电路板制造需要高性能可靠性的覆铜板及半固化片基材。为满足这一需求，在覆铜板及半固化片生产中，就要在半固化片（prepreg，简称为PP，或称：预浸粘结片）的加工设备水平上获得提高。当前，在提高环氧-玻纤布基覆铜板及半固化片加工质量和水平的重点之一，是要克服在浸渍加工中出现的半固化片中含有微小气泡、树脂胶浸透性差、漏浸、胶含量不均匀等问题。这些质量问题的存在，会严重影响此工序以后所制出的覆铜板、多层板的可靠性。     

不流动性半固化片压合白斑的思考

介绍了利用不流动性半固化片在制作刚挠板压合过程中产生白斑的原因，通过对不同条件下（不同敷形材料、表面不同线路图形分布、不同压合压力、不同半固化片张劐不流动性半固化片的压合实验发现，不流动性半固化片的压合与普通半固化片无论是从压合辅材、压合压力及压合模型上来说者研艮大不同。最后通过之前的实验分析，提出了不流动性半固化片的压舍模型。     

用导热性半固化片制造印制板

导热性半固化片对制造导热性电路板,近来变得通用了。实际上,印制电路板是用部分固化的(B-阶段)环氧树脂片或膜,即众所周知的半固化片加工的。半固化片在许多环氧,聚酰亚胺、氰酸脂和PTFE/玻璃纤维组成中是通用的,是为满足工业对高温稳定性、低介电常数和低热膨胀的要求而设计的。 然而,直到现在才能够提供导热的半固化片,同时对制造的PCB保持必要的电气绝缘。现在有效应用的导热的和电气绝缘的半固化片比标准FR-4半固化大10倍以上的导热率和1.5倍以上的介电强度。这些双重性质使之作为电路板组成部分之金属散热器的实际应用     

CAF失效研究之通道的形成

印制线路板行业中,CAF一直令业界困扰和头痛的一个可靠性问题。本文系统的介绍了CAF产生的条件及相关原理。研究了半固化片、波纤布,以及钻孔和去钻污对于CAF的影响。为观察CAF现象,在试验过程中采用平磨切片的方式来观察。希望通过本文,能让大家对于CAF问题有一个全面的认识。     

高速数字设计用的PTFE复合材料

概述了用作半固化片且可在FR-4温度下进行加工,制造简化和成本微调的新复合材料,可以满足高速数字 设计中减少介质损失的要求。     

高标准无铅PCB耐热性及其影响因素研究

针对要求通讯类PCB可承受峰温超过260℃、且无铅回流焊次数达到5次的高标准要求,本项目从PCB的材料选择、工程设计、制造工艺方面出发,建立了PCB耐热性的评测模型,评测了主要的高性能无铅板材、半固化片、PCB设计和PCB制造过程中的层压、钻孔、去钻污等关键工艺过程进行了研究,提升了PCB的耐热性,并建立起高标准无铅PCB的设计和选材规则、制造工艺和品质控制规范。     

不流动半固化片特性的探讨

随着刚挠板、阶梯板与金属基散热板需求量的增大，作为连接材料的不流动半固化的使用量增多。不流动半固化片与普通FR-4半固化片、纯胶片有很大的差别，苓丈结合实验验证，详细分析了不流动半固化片的测试指标、流动性等特性，为不流动半固化片的加工提供了若干建议。     

直接使用半固化片填机械盲孔的研究

机械盲孔是指采用机械钻孔方式形成的盲孔,机械盲孔均需要做填孔处理,并必须保证盲孔被填满,否则,填不满盲孔在后续制程中藏药水,造成盲孔孔铜腐蚀,影响可靠性。业界主要采用两种方式来填机械盲孔:一种是盲孔层采用树脂填孔工艺,另一种是压合时直接利用半固化片熔融的树脂填孔。采用半固化片直接填机械盲孔具有流程短、成本低的特点,是一种优异的加工技术流程。本文对直接使用半固化片填机械盲孔进行了系统的研究,总结出半固化片的树脂种类、Filler含量、树脂含量、生产厂家以及压合程序设计对半固化片填盲孔能力的影响,并分析这些因素影响半固化片填盲孔能力的机理。     

Reliability analysis of redundant-path interconnection networks

The reliability of some redundant-path multistage interconnection networks is characterized. The classes of networks are the generalized indra networks, merged delta networks, and augmented C-networks. The reliability measures are terminal reliability and broadcast reliability. Symbolic expressions are derived for these reliability measures in terms of component reliabilities. The results are useful in comparing network designs for a given reliability requirement     

A reliability and cost analysis of an automatic prototype generatortest paradigm

A cost and reliability model which uses an automatic prototype generator (APG) is presented. According to this model, testers can introduce rapidly prototyped automatically generated codes into the testing phase. The model is called the APG test paradigm (APGTP). Two cases are considered: without a budget constraint, and with both a budget constraint and an objective to maximize the outgoing product reliability. Increased reliability can be attained by applying a five-step procedure. It is shown that the capital requirement for an APG exceeds the available installation cost, then installation of the APG should not be considered unless its reliability per dollar invested exceeds that of the traditional model. To demonstrate the procedures, the costs and reliabilities of the two approaches are compared for certain specified parameter values. The use of APGTP generally produces code of better reliability for the same cost as in traditional testing proposed by D.B. Brown and S. Maghsoodloo (1989)     

Reliability theory for multistate systems with multistate components

An important problem in reliability theory is to determine the reliability of a complex system given the reliabilities of its components. In real life the system and its components are capable of being in a whole range of states, varying from a perfect functioning state to states related to various levels of performance degradation to complete failure. Thus, the binary models are an oversimplification of the actual reality. This paper presents models and their applications in terms of reliability analysis to situations where the system can have whole range of states and all its components can also have whole range of multiple states. The system generally has various levels of operational performance and hence the total system effectiveness measures should reflect all of these performance levels and their reliabilities. The methodology presented is illustrated by a simple example.     

Thermal properties of diamond/copper composite material

Thermal considerations are becoming increasingly important for the reliabilities of the electronics parts as the electronics technologies make continuous progress such as the higher output power of laser diodes or the higher level of integration of ICs. For this reason the desire for improving thermal properties of materials for electronics component parts is getting stronger and the material performance has become a critical design consideration for packages. To meet the demands for a high performance material for heat spreader materials and packages, a new composite material composed of diamond and copper was successfully manufactured under high pressure and high temperature. The effects of diamond particle sizes and the volume fractions of diamond on both thermal conductivity and the coefficient of thermal expansion (CTE) were investigated. The thermal conductivity of the composite material was dependent on both the particle size and the volume fraction of diamond, while the CTE was dependent only on the volume fraction of diamond. At the higher diamond volume fraction, the experimentally obtained thermal conductivities of the composite materials were above the theoretically expected values and the experimentally obtained CTE were between the two theoretical Kerner lines. This may be due to the fact that at the higher diamond volume fraction the diamond particles are closely packed to form bondings between each particle. The composite of diamond and copper have a potential for a heat spreading substrate with high performance and high reliability because not only its thermal conductivity is high but its coefficient of thermal expansion can be tailored according to a semiconductor material of electronics devices.     

A Bayes Reliability Growth Model for A Development Testing Program

The problem of estimating the reliability of a system during development is considered. The development process has several stages at each stage binomial test data are obtained by testing a number of such systems on a success/fail basis. Marginal posterior distributions are derived under the assumption that the development process constrains the reliabilities to be nondecreasing and that the prior distribution for reliability at each stage is uniform. Simulation models are designed to facilitate testing for the validity and computation of the Bayesian model with ordered reliabilities as well as to compare results with other reliability growth models.     

融合拼接大屏幕显示系统可靠性研究及优化策略

分析了当前热门的融合拼接大屏幕显示系统运行机理和主要技术特点。在此基础上,研究了融合拼接与非融合拼接两类大屏幕显示系统可靠性。通过对比和分析,论证了前者可靠度存在薄弱环节。针对不同的应用环境和要求,分别提出了融合拼接大屏幕显示系统可靠性设计优化策略,使其可靠度获得显著提升。     

A scenario-based reliability analysis approach for component-based software

This paper introduces a reliability model, and a reliability analysis technique for component-based software. The technique is named Scenario-Based Reliability Analysis (SBRA). Using scenarios of component interactions, we construct a probabilistic model named Component-Dependency Graph (CDG). Based on CDG, a reliability analysis algorithm is developed to analyze the reliability of the system as a function of reliabilities of its architectural constituents. An extension of the proposed model and algorithm is also developed for distributed software systems. The proposed approach has the following benefits: 1) It is used to analyze the impact of variations and uncertainties in the reliability of individual components, subsystems, and links between components on the overall reliability estimate of the software system. This is particularly useful when the system is built partially or fully from existing off-the-shelf components; 2) It is suitable for analyzing the reliability of distributed software systems because it incorporates link and delivery channel reliabilities; 3) The technique is used to identify critical components, interfaces, and subsystems; and to investigate the sensitivity of the application reliability to these elements; 4) The approach is applicable early in the development lifecycle, at the architecture level. Early detection of critical architecture elements, those that affect the overall reliability of the system the most, is useful in delegating resources in later development phases.     

Reliability optimization of computer-communication networks

The evaluation of the reliability of a given computer communication network is a NP-hard problem. Hence, the problem of assigning reliabilities to links of a fixed computer communication network topology to optimize the system reliability is also NP-hard. A heuristic method is developed to assign links to a given topology so that the system reliability of the network is near optimal. The method provides a way to assign reliability measures to the links of a network to increase overall reliability. It is based on the principle that the most reliable link should be assigned to the most vulnerable edge. The method computes an importance order for the edges of the network and uses the order to assign link reliabilities. If there are fewer than six links in a network, it can be shown that the method gives optimal assignment     

Soft fabric-based flexible organic light-emitting diodes

We reported the first organic light-emitting diodes (OLEDs) on actual soft fabrics that can be used for a wearable display. Polyurethane (PU) and poly(vinyl alcohol) (PVA) layers, which only degrade slightly the flex stiffness of bare fabrics due to their ductile characteristics, were used as planarization layers via a simple fabrication process involving lamination and spin-coating. Therefore, many of the mechanical characteristics of the bare fabric substrates were retained in the planarized fabric substrates. Non-inverted top-emitting OLEDs, designed by considering the optical microcavity effects, were fabricated on a planarized surface by thermal evaporation. The fabricated OLEDs on soft fabrics showed a high current efficiency of around 8 cd/A, reliability during a 1000 cycle bending test with a bending radius of 5 mm, and clear green emission up to an emission angle of 70°. Consequently, we developed high-performance OLEDs on very similar to real fabric via a simple universalized fabrication method.     

化学镍钯金表面处理工艺研究

采用扫描电子显微镜、润湿性、拔/撞锡球和打金线测试等分析手段,比较研究了四家化学镍钯金药水表面处理焊盘的焊接可靠性,同时比较研究了化学镍钯金表面处理和化学镍金表面处理焊盘的焊接可靠性差异.研究表明,化学镍钯金表面处理相对化学镍金表面处理可有效防止镍腐蚀(黑盘)缺陷引起的连接可靠性问题.