The mechanical behavior of interconnect materials for electronic packaging

A variety of new materials are needed for solder interconnects in electronic packages for high- and low-temperature applications. This article compares the mechanical behavior of low-temperature materials (Sn-40In-20Pb, Sn-58Bi, and a silver-loaded conductive adhesive) and high-melting-temperature solders (Sn-3.5Ag, Sn-3.4Ag-4.8Bi, and Sn-4.7 Ag-1.7Cu) to near-eutectic Sn-40Pb solder. The results indicate that there are promising materials alternatives to the traditional Sn-Pb solders in electronic interconnect applications.     

Advances in composite materials for thermal management in electronic packaging

A variety of new advanced composite materials are now available that provide great advantages over conventional materials for electronic packaging thermal control, including extremely high thermal conductivities (more than twice that of copper); low tailorable coefficients of thermal expansion; weight savings up to 80 percent; extremely high strength and stiffness; low-cost, net-shape fabrication processes; and cost reductions as high as 65 percent. In addition, composites are in a state of continual development that will provide even greater benefits. This article provides an overview of advanced composites used in thermal management, including properties, applications, and future trends. The focus is on materials having thermal conductivities at least as high as those of aluminum alloys. Future trends and the potential for composites in other aspects of the electronics industry, such as high-speed assembly machine materials of construction, are also examined. Carl Zweben earned his Ph.D. in applied mechanics at Polytechnic University in 1966. He is currently advanced technology manager and division fellow at Lockheed Martin Missiles and Space, Valley Forge Operations. Author’s Note: In this article, materials consisting of two distinct metals bonded together are referred to as metal-metal composites; the term metal-matrix composites is reserved for metals reinforced with carbon or ceramic fibers or particles.     

UBM凸点互连结构信号完整性分析

建立了凸点下金属层(under bump metallization,UBM)和凸点互连结构仿真分析模型,基于HFSS软件对其高频条件下的信号完整性进行了研究.得到了UBM凸点互连结构表面电场强度分布,分析了UBM各层厚度及不同材料组合变化对UBM凸点互连结构信号完整性的影响.结果表明,不同信号频率下电场强度在凸点及UBM各层表面分布不均匀,越接近UBM顶端电场强度越大;随信号频率的提高,UBM凸点互连结构的回波损耗增大而插入损耗减小;随镍层厚度、铜层厚度和钛层厚度的增加插入损耗减小;采用Ti-Wu-Au组合UBM凸点互连结构的信号完整性最好,Ti-Cu-Ni组合次之,而Cr-Ni-Au组合最差.     

热等静压对电子封装60wt%Si-Al合金组织与性能的影响

采用喷射成形技术制备了新型电子封装材料60wt%Si-Al合金,选用两种热等静压工艺对其进行致密化处理,研究热等静压对材料组织和性能的影响。观察、分析了热等静压致密化后合金组织,测试了热等静压后合金的致密度、导热及热膨胀性能。结果表明,热等静压可有效减少或消除喷射成形60wt%Si-Al合金坯件内部的缩松缩孔,使合金接近理论密度。固态(520℃)热等静压后的合金相比半固态(600℃)热等静压合金,表现出更高的致密度、热导率和更低的热膨胀系数。     

Recyclability and the selection of packaging materials

Costs of solid-waste disposal, concern for environmental impact, and “green” marketing opportunities have placed more attention on recyclability of packaging materials. Recyclability is determined not only by the characteristics of materials themselves, but also by the presence or absence of collection facilities, ease of separation, technology for reprocessing, and markets for recovered materials. By these measures, packaging materials are becoming more recyclable and recyclability is growing in importance as a factor in material selection.     

电子封装技术的研究进展

随着信息时代的到来,电子工业得到了迅猛的发展并带动了与之相关的电子封装业的进步。电子封装技术在现代电子工业中也越来越重要。高功率、高密度、小型化、高可靠性、绿色封装已是当代电子封装技术的主要特征。随着电子产品设备向微型化、大规模集成化、高效率、高可靠性方向的发展,对封装材料、技术及可靠性提出了越来越高的要求。本文简要介绍了目前电子封装材料、技术以及可靠性的基本要求和研究进展,并对未来的发展方向趋势进行了分析评述。     

电子封装技术专业教学改革与实践

随着电子产品微型化的发展,电子封装技术成为电子工业中的关键制造技术之一。与之相匹配的人才的教育与培养成为该领域的重要研究课题。探讨国内在电子封装技术专业教学改革与实践,发现本专业应该从前沿封装技术、实际广泛应用的封装技术、以及与之关系密切的制造技术三方面培养专业性人才,使学生能够对目前工业中封装技术的应用有着较为全面的认识和扎实的基础。     

Investigating the thermal-plasma processing of advanced materials

Due to several inherent advantages, plasma processing technology may become a very useful tool in the production of new materials. An increasing research effort based on experimental as well as theoretical investigations has been invested in this area for the synthesis of advanced materials. In describing the thermal-plasma processing technique, this article employs examples from research at the Plasma Processing Laboratory at the University of Idaho.     

大功率高可靠电子封装研究发展趋势

建立了球栅阵列封装(ball grid array, BGA)焊点有限元分析模型,基于ANAND本构方程,分析了BGA焊点在功率循环载荷下应力与应变的分布情况,并搭建试验平台,完成了功率循环载荷下BGA封装器件应力与应变的测量试验,验证了仿真分析的可行性. 选取焊点高度、焊点直径、焊盘直径和FR4基板厚度完成了正交试验分析,通过非线性回归分析得到高拟合度的BGA焊点功率循环应力量化评价模型. 结果表明, BGA焊点结构参数对焊点应力影响大小排序为焊盘直径、FR4基板厚度、焊点直径和焊点高度,焊盘直径对BGA焊点应力影响显著,焊点直径、焊点高度和FR4基板厚度对BGA焊点应力影响不显著;最优参数水平组合为焊点高度0.39 mm、焊点直径0.42 mm、焊盘直径0.34 mm和FR4基板厚度0.8 mm,最优水平组合下BGA焊点应力与应变明显降低.     

高温电子封装无铅化的研究进展

为电子封装无铅化的全面实施对受RoHS指令暂时豁免的高铅钎料是个严峻挑战,发展高铅钎料替代品及新型无铅化工艺势在必行.本文介绍了Ag粉烧结和低温固液扩散2种无铅高温互连工艺,并对几种有潜力的元铅钎料进行了评速,包括Zn基和Bi-Ag系钎料、Bi基复合钎料和Au基钎料等.在此基础上,探讨了高温无铅钎料及高温无铅互连技术的发展趋势.     

不同电子封装结构的随机振动分析

基于ABAQUS有限元软件,对同一PCB板上的QFP和PBGA两种不同封装结构,在随机振动载荷下的应力场进行了研究,并对不同封装结构性能进行了比较分析.结果表明,在随机振动载荷下,无论是QFP封装组件还是PBGA封装组件,越靠近PCB板边缘,器件的应力值越大;在同等条件下,PBGA封装器件的应力值要高于QFP封装器件;以同类封装器件中最大应力值的10%为临界点,封装器件中应力值比最大应力值低10%以上的为非薄弱元器件,其余均定义为薄弱元器件.根据该定义,对于5组QFP封装器件而言,QFP-1器件和QFP-5器件为薄弱元器件;而对于5组PBGA封装器件,仅有PBGA-3器件为非薄弱元器件.     

电子互连无铅钎料及焊点蠕变行为研究进展

针对近年来无铅钎料及焊点的蠕变失效问题,综合评述了蠕变变形行为及其在焊点可靠性评估中的应用。首先系统地介绍无铅钎料的蠕变行为,探讨含合金元素/颗粒无铅钎料蠕变性能改性机制。其次评述焊点蠕变行为,探讨焊点成分以及不同基板材料对焊点蠕变特性影响的研究进展。再次结合具体电子器件,采用有限元模拟,分析基于有限元的焊点蠕变响应及疲劳寿命预测,评估焊点可靠性。最后针对无铅钎料及焊点蠕变行为的未来发展进行展望,分析其研究中存在的问题及解决办法,为焊点可靠性进一步研究提供理论支撑。     

AlSiC电子封装基片的制备与性能

采用模压成形制备SiC预制件和真空压力浸渗相结合的技术,成功制备出AlSiC电子封装基片。研究磷酸铝含量和成形压力对SiC预制件抗弯强度和孔隙率的影响规律,并对所制备的AlSiC电子封装基片的性能进行评价。结果表明,在磷酸铝含量为0.8%,成形压力为200MPa时,经600℃恒温2h处理的SiC预制件抗弯强度为8.46MPa,孔隙率为37%。当温度为100~500℃时,AlSiC电子封装基片的热膨胀系数介于6.88×10-6和8.14×10-6℃-1之间,热导率为170W/(m·K),抗弯强度为398MPa,气密性小于1×10-8Pa·m3/s。用钯盐活化进行化学镀镍,得到光亮、完整的镀层。镀层于450℃恒温120s后,镀层不变色,未见起皮和鼓泡。     

纳米金属颗粒膏合成及其低温烧结连接的电子封装应用研究进展

针对微电子元器件及其高密度系统制造,特别是大功率器件互连封装中无铅、低温互连而其接头又具有良好高温性能的需求,以作者课题组的研究为例,基于金属纳米颗粒具有高表面能的特性,简要概述其低温烧结连接用于电子封裴的原理、纳米颗粒膏的合成、低温烧结连接工艺因素对接头性能的影响及其发展趋势。