摘要
最近兩年，微電子元件內常觀察到一種所謂『大規模剝離』(Massive spalling)之失效現象，對電子元件之可靠度造成嚴重之威脅。Massive spalling指的是原來位於界面之介金屬離開界面往銲料內部移動，且spalling的發生是橫跨整個銲點而非局部之現象。此一現象已經在許多不同的材料系統中普遍被觀察到，包括錫銀銅(SnAgCu)銲料與鎳(Ni)基材之反應、錫鋅(SnZn)銲料與銅(Cu)基材之反應、高鉛銲料(PbSn)與銅(Cu)基材之反應、以及高鉛銲料(PbSn)與鎳(Ni)基材之反應。產業界與學術界對此一獨特之現象迄今皆無合理之解釋。本研究藉由熱力學的觀點對於此一現象給予一合理的解釋。
關鍵字
無資料並列摘要
Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With the growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a non-equilibrium phase, and the spalling of the original intermetallic occurs.