Collaborative Research: Solid-Liquid Interactions during Transient Liquid Phase Bonding

先进的热力学和相场模型的结合，再加上实验，将使我们能够理解瞬间液相连接(TLP)过程中的固/液相互作用。更好地了解固/液界面现象有望使TLP键合变得可行，并将为电子焊接提供一种环保的替代方案。这项研究将研究控制界面相互作用的新方法，以减小接头宽度，缩短焊接时间，改善TLP接头特性。这些措施包括通过去除不可润湿的氧化层的稳定性来改善低温下的成分润湿，以及通过应用瞬时扩散阻挡层来保持平面的固/液界面。将通过工艺参数和扩散障碍解决金属间化合物的析出问题。探索的现象也适用于凝固、液相烧结和其他毛细驱动的连接过程。成功实现本提案的目标将有助于开发更好的、环境友好的电子制造技术。含铅合金被广泛用作电子产品的焊接材料。不幸的是，糟糕的可回收性使电子垃圾成为土壤/水铅污染的主要来源。因此，使用更环保的替代品具有很强的推动力。尽管取得了长足的进步，但大多数无铅焊料需要更高的键合温度，导致残余热应力增加，从而降低互连可靠性。预计从这项研究中获得的理解将有助于最终淘汰危险的、含铅的微电子元件。

The combination of advanced thermodynamic and phase-field models, coupled with experiments will allow the understanding of solid/liquid interactions during Transient Liquid Phase (TLP) bonding. Better understanding of the solid/liquid interfacial phenomena is expected to make TLP bonding viable and will provide an environmentally-friendly alternative for electronic soldering. This research will study new approaches to control interfacial interactions to reduce joint width, shorten the bonding time, and improve the TLP joint characteristics. These include improving the compositional wetting at low temperatures through the de-stabilization of non-wettable oxide layers and maintaining a planar solid/liquid interface by applying transient diffusion barrier layers. The precipitation of Intermetallic Compounds will be addressed through processing parameters and diffusion barriers. The explored phenomena apply also to solidification, liquid phase sintering and other capillary-driven joining processes.The successful attainment of the objectives of this proposal will contribute to the development of better, environmentally-friendly electronic manufacturing techniques. Lead-containing alloys are extensively used as soldering materials for electronics. Unfortunately, poor recyclability makes electronic waste a major source for soil/water lead contamination. There is thus a strong driving force for the utilization of more environmentally-friendly alternatives. Despite considerable progress, most Pb-free solders require higher bonding temperatures, resulting in increased residual thermal stresses that reduce interconnect reliability. It is expected that understanding gained from this study will contribute to the ultimate phase-out of hazardous, lead-containing microelectronics components.