新一代无铅兼容PCB基板材料的最新研究进展（1）

在实施两个指令的促进下,当前世界覆铜板的制造技术出现了迅猛的发展,笔者以2006年以来的文献为基础,概述了无铅安装对环氧基覆铜板用固化剂的促进,分析了无铅兼容覆铜板的性能以及性能之间的关系。同时,对无铅兼容覆铜板去钻污特点、导电阳极丝(CAF)与互连应力测试(IST)等研究热点进行了评述。     

高耐热、低膨胀系数覆铜板开发思路

欧盟两指令的正式实施标志着全球电子行业进入了无铅焊接时代,由于无铅焊接温度的提高,对覆铜板热可靠性的要求相应提高;随着印制电路多层化和IC封装技术的发展,为了提高互联与封装的可靠性,稳定性,不仅要求板材具备高耐热性,而且要兼备低的热膨胀系数（CTE）。为此国内外业界都在积极开发高耐热、低热膨胀系数的覆铜板。本文就此类覆铜板用树脂体系的开发思路及工艺设计方案思路进行探讨。     

CEM-1覆铜板的研制

本文介绍了CEM-1覆铜板用环氧树脂的增韧改性、CEM-1覆铜板的制作及其性能。     

新型高韧性高Tg无铅覆铜板材料介绍

从无铅时代的全面到来,时至今日,数年间,日新月异的无铅兼容材料层出不穷,在我们不懈追求材料的耐热性与高Tg以满足高多层板、HDI等现今各类高端产品的应用时,材料的PCB加工性、韧性、粘结性等性能同样是一个不容忽视的重要参数。一旦忽视了这一点,PCB业端出现导通孔裂缝、基材冲/钻孔掉渣、孔壁电镀层环裂、铜箔脱落、基材层间分层等缺陷的几率将大大增加。文章介绍了一种性能均衡的覆铜板,是同时拥有高韧性、高剥离强度与优良钻孔加工性的高Tg(Tg≥170℃)无铅制程兼容的覆铜板材料。     

一种综合评价覆铜板脆韧性的表征方法的研究

迄今为止,现有的方法都无法准确表征覆铜板的脆韧性。可评判金属及塑料样品脆韧性的测试方法,都不能直接评判覆铜板样品。由于覆铜板中多层玻璃布粘合的影响,使得这些测试方法只能反映某一方面的性能。本文采用叠加公式法进行综合评判,可以准确地反映覆铜板的脆韧性。     

一种无卤型纸基覆铜板制备方法的探讨

为了适应“无铅制程”和“无卤基板材料”的绿色环保发展趋势,覆铜板行业广大技术人员正不断的研发新型的环保型覆铜板。文章主要从纸基覆铜板树脂胶黏剂的组成--阻燃剂这一方面研究,探讨一种无卤环保纸基覆铜板的制备方法。     

无卤、无铅与印制电路板

主要叙述覆铜板和电路板的无卤、无铅技术发展趋向,并对欧盟、美、日之间的共同点与差异点作以比较,供业界参考。     

导热绝缘层的韧性及附着力影响因素分析

铝基覆铜板作为电子元器件的载体,以其优异的散热性能,广泛应用于LED、汽车、电视、电源等领域。但由于铝基覆铜板的导热绝缘层附着力差,且导热绝缘层本身韧性低,机械加工时容易出现导热绝缘层崩裂、分层的现象,这是铝基覆铜板开发及制作过程中面临的最大难题之一。本文采用柱轴弯曲试验来评估导热绝缘层的韧性及附着力,并分析了影响铝基覆铜板导热绝缘层韧性及附着力的因素,从试验条件、铝板表面处理方式、导热绝缘层厚度、导热绝缘层配方等方面进行对比,评估不同因素对韧性及附着力的影响情况。     

文献与摘要（86）

实现器件超小型向立体电路进化的“MIPTEC”技术;无铅焊锡材料设计之发展趋势;高耐热、低膨胀系数覆铜板开发思路;     

行业信息

CCLA秘书处积极策划第七届全国覆铜板技术·市场研讨会(2006年行业年会)CCLA秘书处正在积极策划2006年度的行业年会。本次年会内容将以市场研讨为主。技术方面将以无铅兼容覆铜板及原材料为主。报告专家的阵容,将比去年更加强大。目前正在积极与美国IPC,全球著名大公司、国内权威机构等联络,多数已经落实。计划于7月底召开,会址有可能选择在长江三角洲地区某市。(CCLA秘书处报道)CCLA完成2005年度全国覆铜板行业调查统计分析五月中旬,CCLA秘书处完成了对2005年度全国覆铜板行业的调查统计分析工作,并编制了调查统计分析报告。该报…     

环氧基材PCB对无铅焊锡装配适应性的研究

讨论了环氧基材PCB对无铅焊锡装配的适应性、铜竭顶的可靠性，证明双氰胺固化的环氧基材不能适直无铅焊锡装配：酚醛树脂固化的环氧基材有解决此问题可能性，但都是PCB制造商们的技术决窍。     

“无铅”覆铜板耐化学性改善探讨

文章简要介绍了提高“无铅”覆铜板耐化学性的重要意义，在实验数据的基础上，分析出影响“无铅”覆铜板产品耐化学性的主要因素，并提出改善措施。     

高性能覆铜板用氰酸酯增韧研究进展

氰酸酯是今年发展起来应用于高性能覆铜板的一种新型的高分子材料,它具有优异的耐热性,较低介电常数,低介电损耗,优异的耐湿热性等优异性能,文章对氰酸酯的增韧方法,机理及其在高性能覆铜板的应用进行了综述.     

文献与摘要（84）

由设计来改进生产效率；生产方便的激光直接成像技术；热传导微波材料；应用无铅安装中印制板绝缘性降低；电子产品完好监控、识别和诊断……     

Transition of MCM-C applications to MCM-L using rigid flex substrates

Rigid flex circuits have historically been used in military and high-end performance electronic packaging to improve reliability, reduce weight and save space. This type of interconnect offers higher reliability and a tighter form factor when compared to more conventional interconnect techniques. Improvements in printed circuit fabrication processes and laminate materials have made possible unique opportunities for high density rigid flex circuitry. Recently MCM-L or laminate based multi chip modules have been gaining in popularity as a lower cost packaging alternative to traditional MCM-C or ceramic substrate based multi chip modules. This paper describes the steps taken to redesign existing modules from MCM-C technology to MCM-L(F). Several actual products that have been redesigned from ceramic substrate technology to laminate based packaging using rigid flex as the enabling technology are shown. Data is presented on thermal dissipation, mechanical reliability, electrical performance, and thermal reliability of the laminate substrate as well as assembly information.     

RCC与不同FR-4基板积层结构的Tg考察

文章采用常规RC(C涂树脂铜箔)与不同型号、不同厚度的FR-4基板一次积层制作了不同组成的积层板结构,并对不同型号、不同厚度的基板及其与RCC积层前后的Tg测试分析,结果表明具有不同Tg水平的基板与该RCC积层之后的总Tg几乎不受RCC的Tg影响,仍然为芯板的Tg。     

Hierarchical Toughening of Nacre‐Like Composites

Reinforced polymer‐based composites are attractive lightweight materials for aircrafts, automobiles, and turbine blades, but still show strength and fracture toughness lower than traditional metals. An interesting approach to address this issue is to fabricate composites with structural features that absorb part of the elastic energy stored in the material during fracture through extrinsic and intrinsic toughening mechanisms behind and ahead of the crack tip, respectively. Inspired by the nacreous layer of mollusk shells, the fracture behavior of multiscale composites that combine intrinsic toughness from a brick‐and‐mortar structure connected through nanoscale mineral bridges and extrinsic toughness arising from a brittle–ductile laminate architecture at the millimeter scale are fabricated and investigated. Such a hierarchical toughening approach increases the dissipated energy by more than 30‐fold during fracture with minimal loss in stiffness and strength. Using simple energy balance arguments and fracture mechanics concepts, guidelines are established for the design of nacre‐like composites with a remarkable combination of stiffness, strength, and toughness. This demonstrates the possibility to controllably introduce toughening mechanisms at different length scales and to thus fabricate hierarchical composites with high fracture resistance in spite of the brittle nature of their main inorganic constituents.     

氧化诱导时间和氧化诱导温度测试方法在覆铜板中应用

文章介绍了用差示扫描量热法（DSC）测试氧化诱导时间和氧化诱导温度的测试原理和方法。结合作者在覆铜板工作的实际经验,指出了UL认证在研发工作中的局限性,并以简单例子阐述了氧化诱导时间测试方法在覆铜板中的应用。     

Effect of Lead-Free Soldering on Key Material Properties of FR-4 Printed Circuit Board Laminates

The transition to lead-free soldering of printed circuit boards (PCBs) using solder alloys such as SnAgCu has resulted in higher temperature exposures during assembly compared with eutectic SnPb solders. The knowledge of PCB laminate material properties and their dependence on the material constituents, combined with their possible variations due to lead-free soldering temperature exposures, is an essential input in the laminate selection process. This paper provides laminate selection guidelines that were arrived at by assessing key material properties (glass transition temperature, coefficient of thermal expansion, decomposition temperature, and water absorption), and their responses to lead-free soldering assembly conditions. A range of commercially available FR-4 PCB laminate materials, classified on the basis of glass transition temperature (high, mid, and low), curing agents (dicyandiamide and phenolic), flame retardants (halogenated and halogen-free), and fillers (presence or absence) were studied. The laminate material properties under investigation were measured as per the IPC-TM-650 test methods before and after exposure to multiple lead-free soldering cycles. Combinatorial property analysis was conducted to investigate the causes behind variations in material properties.