SBIR Phase I: Stable Undercooled Metal Materials for Soldering Heat-Sensitive Components and Substrates

这个SBIR一期项目将使柔性和印刷电子技术能够用于热敏材料，如塑料、纸张和有机电子产品，这些材料由于温度、成本和/或性能限制而不能使用传统的焊接或导电粘合剂。这项拟议研究的基础是一种由液态金属颗粒制成的无加热锡膏，这种锡膏的作用就像填充的气球，在破裂时释放液态金属，然后变成固体。印刷电子产品为美国制造业的主要增长提供了潜力，因为这种设备结构适合在国内制造，具有运输优势和整体较低的拥有成本。这项技术可以应用于商业柔性显示器、可穿戴生物医学传感器、军用设备的轻型电子设备以及供应链连接的射频识别标签。该技术支持的产品的开发有望使美国公民、机构、军队和政府机构通过更好的库存/废物跟踪、生物识别收集、减轻重量和物体网络更高效。启用新的美国技术为物联网和远程医疗创造了市场机会，也为在美国制造电子产品创造了制造机会，创造了大量的就业机会、企业和税收。该项目专注于开发独特的过冷金属微粒，用于印刷/柔性电子产品的无热焊接。这项研究将把加热与金属的接合分离开来。显著降低加工温度，从而保持热敏电子和基板的功能。创新的关键是什么？氧化物封装外壳？防止非均相成核与薄氧化壳和过冷的增强在微纳米尺度。它可以被机械剪切或通过化学通量作用去除，使内部的液态金属首先流动和凝聚，然后固化。这种金属合金可以在室温下以液体的形式保存数月。研究将提高在139°C熔化的铋合金的产量和可靠性，而在217°C熔化的锡/银/铜SnAgCu焊料则不那么脆。目标是1)开发一种可以在不加热的情况下将固体金属连接/涂覆材料的材料，2)展示与导电粘合剂和传统焊接相比的连接特性，以及3)展示惠斯通电桥和柔性微机电系统（MEMS）原型设备。过冷焊料将使用助焊剂策略在室温下制造机械和电气坚固的电子设备接头。

This SBIR Phase I project will enable the use of flexible and printed electronic technologies for heat-sensitive materials such as plastics, papers, and organic electronics that cannot employ traditional soldering or conductive adhesives because of temperature, cost, and/or performance limitations. The foundation for the proposed research is a no-heat-added solder paste made from liquid-metal particles that act like filled balloons, releasing a liquid metal when popped and then turning solid. Printed electronics offer potential for major manufacturing growth for the United States, because the device structure lends itself to being manufactured domestically, offering transportation advantages and overall lower costs of ownership. This technology may have applications in commercial flexible displays, wearable biomedical sensors, lightweight electronics for military equipment, and radio frequency identification tags for supply-chain connectivity. The development of the products enabled by this technology is expected to make U.S. citizens, institutions, military, and government agencies more efficient and effective with better inventory/waste tracking, biometrics collection, weight reduction, and object networking. Enabling new U.S. technologies creates market opportunities for the Internet of Things and telemedicine, as well as manufacturing opportunities to make electronics in the U.S., creating significant jobs, businesses, and tax revenue. This project focuses on developing unique undercooled metal microparticles for use in no-heat-added soldering of printed/flexible electronics. The research will decouple the heating from the joining of the metal?significantly lowering the processing temperature and thus preserving function for heat-sensitive electronics and substrates. The key to the innovation?an oxide encapsulating shell?prevents heterogeneous nucleation with a thin oxide shell and undercooling's enhancement on the micro- and nanoscale. It can be mechanically sheared or removed by chemical flux action to enable the liquid metal inside to first flow and coalesce, and to then solidify. The metal alloys can remain as liquids at room temperature for months. Research will increase the production yield and reliability of bismuth alloys that melt at 139°C to less brittle tin/silver/copper SnAgCu solder that melts at 217°C. Objectives are to 1) develop a material that can join/coat materials with solid metal without adding heat, 2) demonstrate the properties of the joint compared to conductive adhesives and traditional soldering, and 3) demonstrate a Wheatstone bridge and flexible Micro Electro Mechanical Systems (MEMS) prototype device. Undercooled solders will be applied using flux strategies to make mechanically and electrically robust joints in an electronic device at room temperature.