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

结合先进的热力学和相场模型，再加上实验，将使我们能够理解瞬态液相（TLP）键合过程中的固/液相互作用。更好地理解固/液界面现象有望使TLP键合可行，并将为电子焊接提供一种环保的替代方案。本研究将研究控制界面相互作用的新方法，以减小关节宽度，缩短粘接时间，改善TLP关节特性。这包括通过去除不可湿性氧化层来改善低温下的润湿性，以及通过施加瞬态扩散阻挡层来保持平面固/液界面。金属间化合物的析出将通过工艺参数和扩散障碍来解决。所探索的现象也适用于凝固、液相烧结和其他毛细管驱动的连接过程。这项建议的目标若能成功达成，将有助发展更佳、更环保的电子制造技术。含铅合金广泛用作电子产品的焊接材料。不幸的是，较差的可回收性使电子废物成为土壤/水铅污染的主要来源。因此，使用更环保的替代办法具有强大的推动力。尽管取得了相当大的进展，但大多数无铅焊料需要更高的粘合温度，从而导致残余热应力增加，从而降低了互连的可靠性。预计从这项研究中获得的理解将有助于最终淘汰有害的含铅微电子元件。

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.