Fluxless bonding process in air using Sn–Bi–Au design
Fluxless bonding process in air using Sn–Bi–Au design
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DOI：
10.1016/j.msea.2004.01.009
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发表时间：
2004-05
期刊：
影响因子：
6.4
通讯作者：
Dongwook Kim;Chin C. Lee
中科院分区：
文献类型：
--
作者：
Dongwook Kim;Chin C. Lee
提出了一种新的基于Sn-Bi-Au设计的无钎焊技术。采用扫描电镜（SEM）、x射线衍射仪（XRD）和x射线光电子能谱（XPS）研究了Au/Sn/Bi薄膜的微观结构和相生长机理。发现金-锡金属间化合物晶体在富bi基体中随机分布，形成顶盖层。ausn2和ausn4晶粒的平均尺寸分别为756和667Å。粘接过程在250°C的空气中进行，不使用助焊剂。节理具有较高的抗剪强度，达到4.9kg，且节理仅有少量空洞。测得熔点为225℃。焊点由近共晶Sn-Bi合金组成，焊点内嵌有带状的AuSn2+ ausn4金属间化合物层。Sn-Bi-Au焊点断裂主要发生在Au-Sn金属间层与富锡区界面处。这种制造方式是延展性的。无焊剂的过程是兼容的许多拾取和放置机器，在环境空气中操作。
A new fluxless bonding technique using Sn–Bi–Au design is presented. Microstructure and phase growth mechanism of as deposited Au/Sn/Bi films were first studied by scanning electron microscopy (SEM), X-ray diffraction method (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the crystallites of Au–Sn intermetallics are randomly distributed in Bi-rich matrix that forms a top-capping layer. The average size of AuSn2and AuSn4crystallite are 756 and 667Å, respectively. The bonding process was performed at 250°C in air without the use of flux. The resulting joints exhibit high shear strength of 4.9kg and show only a few voids. Melting temperature of 225°C was measured. The joint is composed of near eutectic Sn–Bi alloy with ribbon shaped AuSn2+AuSn4intermetallic compound layer embedded inside the solder joint. The fracture of the Sn–Bi–Au solder joint mainly occurs along the interface between the Au–Sn intermetallic layer and the Sn-rich regions. This facture mode is ductile. The flux-free process is compatible with many pick-and-place machines that operate in ambient air.