增强相对无铅焊点电迁移行为影响的研究.docVIP

  增强相对无铅焊点电迁移行为影响的研究 左勇，马立民，刘思涵，赵然，郭福** （北京工业大学材料科学与工程学院，北京 100124） 5 10 摘要：微型化和多功能化的需求促使单个焊点所需承受的电流密度不断增加，这使得电迁移 现象成为了重要的可靠性问题之一。焊点电迁移行为的抑制可通过结构优化和材料改性两种 方法实现。本文从材料改性的角度出发，采用观察焊接接头显微组织演变的方法，分析和讨 论了 0.2wt.%Co 元素的添加以及内生 5vol.%Cu6Sn5 相的方法对焊点电迁移行为的影响。结 果显示，微量元素 Co(0.2wt.%)的添加和内生 Cu6Sn5(5vol.%)相的形成对于钎料接头的电迁 移损伤具有有效的缓解作用。Co 元素促使 Ag3Sn 相弥散分布形成 Cu 原子迁移的屏障，同 时对于(Cu, Co)6Sn5 的迁移起到钉扎作用。内生 Cu6Sn5 相在基体中的形成改变了界面处 Cu 原子的化学浓度梯度，从而抑制了 Cu 原子的迁移。 关键词：合金化；复合钎料；电迁移 中图分类号：TG425+.1 15 The Effects of Reinforcement Phases on Electromigration Behaviors in Lead-free Solder Joint ZUO Yong, MA Limin, LIU Sihan, ZHAO Ran, GUO Fu (College of Materials Science and Engineering, Beijing University of Technology, 20 25 30 35 40 Beijing 100124) Abstract: The requirements of miniaturization and multifunctional for microelectronic devices lead to the current density which imposes on the solder joint continuous increase. Therefore, electromigration (EM) is becoming a standout reliability issue for lead-free solder. Structural optimization and material modification are considered to be the possible methods for alleviating EM damage. This study investigates the impact of 0.2wt.% Co additions and in-situ 5vol.% Cu6Sn5 , which were introdued into solder matrix by alloying and fabricating composite solder approaches respectively, on electromigration from the perspective of material modification. The results indicated that both 0.2wt.% Co and in-situ 5vol.% Cu6Sn5 played an effective role in inhibiting EM behavior. Co element additions made Ag3Sn intermetallic compounds disperse homogeneously in solder matrix and as a barrier to Cu atoms diffusion. Moreover, (Cu, Co)6Sn5 phase migration was pinned by Co addition. In-situ Cu6Sn5 phase suppressed EM by changing the chemical concentration gradient of Cu atoms at the interface. Keywords: Alloying; Composite; Electromigration 0 引言 随着电子器件微型化和多功能化的发展，焊点上不断增加的电流密度和电流密度的不均 匀分布已经成为影响焊点可靠性的重要因素[1]。因此，高温高电流密度引起的可靠性问题获 得广泛关注。电迁移是焊点在电和热的共同作用下引起物质迁移的现象。[2]电迁移过程中的 极化