球栅阵列无铅焊点随机振动失效研究

通过非接触式激光全息激振方法对试件(电路板组件)进行试验模态分析,了解其动态特性;以其第一阶固有频率作为中心频率,分别进行了三种不同加速度功率谱密度幅值的窄带随机振动疲劳试验,并对失效焊点进行金相剖面分析,探究球栅阵列(BGA)无铅焊点在随机振动载荷下的失效机理。结果表明,三种加速度功率谱密度幅值的随机振动试验中BGA无铅焊点的失效机理不尽相同,随着功率谱密度幅值增加,焊点失效位置由靠近电路板(PCB)一侧向靠近封装一侧转变,分别是靠近PCB一侧的焊球体,焊点颈部以及靠近封装一侧的Ni/金属间化合物(IMC)界面处,相应的失效模式由疲劳断裂转为脆性断裂     

基于无铅SMT焊膏印刷参数优化控制研究

无铅表面组装制程是以模板印刷、表面贴装元件放置、回流焊或波峰焊为主要步骤.其中模板印刷制程在生产线中扮演第一个重要的步骤.文章设计了"印刷结果观测数字化实验"方法,并找出模板印刷工艺无铅化生产的最优化工作参数,得出NP-04LP丝网印刷机,0.127mm厚的不锈钢模板在使用Loetite LF320无铅焊膏时,考虑SM...     

非松香基无卤素固体助焊剂成分的优化设计

随着电子组装无铅化进程的推进,传统的松香基助焊剂已很难适应无铅药芯焊锡丝的手工烙铁焊接工艺的需要。本试验研究了一种专用于无铅药芯焊锡丝的非松香基的固体助焊剂,并对其组成成分进行了优化设计。优化后的最佳成分配比为：己二酸（8%）、癸二酸（1%）、十八酸（36%）、松香（35%）、聚乙二醇（18%）、OP-10（0.9%）...     

Ce的添加对SnAgCu系钎料组织和性能的影响

通过向Sn-0.3Ag-0.7Cu系无铅焊料中添加微量稀土Ce,研究不同稀土含量对Sn-0.3Ag-0.7Cu合金的熔化温度和润湿性的影响,同时利用扫描电子显微镜(SEM)对焊料的显微组织进行了分析.实验结果表明,添加Ce对焊料的熔化温度影响不大,但对合金的润湿性和微观组织影响较大.当ω(Ce)=0.10%时,焊料合金的综合性能较好.     

稀土元素对无铅焊料性能的影响

随着公众环保意识的增强,含铅焊料的发展和应用受到了极大的限制,研制新型的、环境友好的无铅焊料来取代传统的锡铅焊料成为近年来研究的热点,而添加微量元素合金化以获得性能优异的无铅焊料尤其受到研究者的关注。本文系统地综述了添加微量稀土元素对无铅焊料物理化学性能、显微组织、力学性能、电迁移及锡晶须生长等的影响,并对稀土元素在无铅焊料中的应用及发展趋势进行了展望。     

The anomalous microstructural,tensile, and aging response of thin-cast Sn3.9Ag0.6Cu lead-free solder

In this study, bulk and thin-cast samples were produced with an identical Sn3.9Ag0.6Cu composition. The thin-cast material exhibited a much finer as-quenched microstructure than the bulk material with the intermetallic compound (IMC) phase restricted to a thin network. Both the bulk and thincast materials continually softened during room-temperature aging, while both materials initially softened and then subsequently hardened when aged at 120°C and 180°C. The thin-cast material was in all cases significantly softer than the bulk material, and responded to aging as if it were bulk material aged at a higher temperature. These results have significant implications for the elevated temperature application of Sn3.9Ag0.6Cu.     

锡-银系无铅焊料动态强度研究

利用分离式霍普金森压杆试验技术,在室温下研究了锡-银系无铅焊料在高应变率条件下的动态压缩力学性能。结果表明,锡-银系无铅焊料有显著的应变率效应:随着应变率的增加,材料的屈服强度和流动应力有显著的提高;在对数坐标系下其动态屈服强度随应变率呈线性变化,证明锡-银系焊料是一种很有希望替代锡铅焊料的无铅焊料。最后根据Malvern过应力理论建立了锡-银系无铅焊料的动态本构关系。     

Effect of bismuth on the isothermal fatigue properties of Sn-3.5mass%Ag solder alloy

Sn-3.5mass%Ag eutectic solder is selected as a candidate base alloy for replacing the eutectic Sn-Pb, and the effect of bismuth (2, 5, 10mass%) on the fatigue life of bulk Sn-3.5mass%Ag eutectic at room temperature has been studied over the total strain range from 0.3 to 3 percent in tension-tension mode. Fatigue life is defined as the number of cycles at which the load decreases to a half of the initial value. The fatigue life dramatically decreases with increasing contents of bismuth and adding this element over 2% makes fatigue life shorter than that of tin-lead eutectic alloy. Tensile strength of the alloy significantly increases with an increase in bismuth contents due to solid solution hardening (<5%Bi) or dispersion strengthning of fine bismuth particles, while ductility of this system dramatically decreases with increasing bismuth contents. Fatigue life of these alloys depends on ductility obtained by tensile test. The fatigue life of Bi containing Sn-3.5%Ag alloys can be described by, (Δε_p/2D)·N _f ^0.59 =0.66 where N_f is fatigue life defined by number of cycles to one-half load reduction, Δε_p is the plastic strain range for initial cycles, D is the ductility as measured by reduction in area.     

无铅焊接技术最新进展及评述

介绍了国内外相关的无铅焊料的发展状况、无铅设备及其工艺的特殊要求及主要问题。介绍了无铅焊接产品的可靠性检测与评价技术的最新状况以及无铅焊点的寿命理论的最新进展。并对无铅焊接特有的质量问题及解决方法进行了评述。     

影响封装和PCB结构的技术动力

概述了影响电子封装PCB结构的技术推动力。IC的进步和电子产品性能的提高是关键因素。