Fundamental Understanding of Anisotropic Conductive Film (ACF) for Flip Chip Packaging

本研究的目的是促进对各向异性导电胶粘剂行为的基本理解，这种胶粘剂可以取代电子封装中的含铅焊料。特别令人感兴趣的是制造这种材料的薄膜（ACF）的能力，这种薄膜稳定，具有高电流密度容量。用替代互连材料取代含铅焊料将对微电子封装系统的制造工艺产生重大影响，如倒装芯片、球栅阵列（BGA）、芯片规模封装（CSP）和表面贴装技术（SMT）。ACFs是替代含铅焊料作为互连材料的候选材料之一。目前，这些ACF材料的可靠性和性能没有竞争力，改进需要更好地理解电子封装过程中开发的界面行为。本项目将研究ACA材料的化学和物理性能，并对ACF接头中的界面进行研究。然后，通过使用缓蚀剂和（或）牺牲合金来修改界面，以保持极端环境下的电性能。为了提高ACA的电流密度，将用自组装分子线（SAM）修饰界面。ACA与芯片衬垫/衬底衬垫之间的机械键合界面将被SAM修改，SAM已经被认为能够提供高电流密度。将开发加工-属性关系的计算模型。在授奖期间，PI将继续解决研究和教育的一体化问题，具体活动的重点是高中教师和来自当地高中代表性不足群体的学生。

The goal of this research is to advance the fundamental understanding of the behavior of anisotropic conductive adhesives that could replace lead-containing solders in electronic packaging. Of particular interest is the capability of creating a thin film (ACF) of this material that is stable, with a high current density capacity. Replacing lead-containing solder with alternative interconnect material would significantly impact the manufacturing processes of microelectronic packaging systems, such as flip-chip, ball grid array (BGA), chip scale package (CSP), and surface mount technology (SMT). ACFs are one of the candidates to replace lead-containing solder as interconnect material. Currently, the reliability and performance of these ACF materials are not competitive, and improvements require a better understanding of the interfacial behavior developed in electronics packaging processes. In this project, chemical and physical properties of ACA materials will be studied, and the interfaces in ACF joint will be investigated. Then, the interfaces will be modified to maintain the electrical properties in extreme environment by using corrosion inhibitors and or sacrificial alloys. To improve the current density of ACA, the interfaces will be modified with self-assembling molecular (SAM) wires. The mechanically bonded interface between ACA and chip pad/substrate pad will be modified by SAM, which has been known to be able to deliver high current density. A computational modeling of the processing - property relationship will be developed. During the period of award, the PI will continue to address the integration of research and education with specific activities focused on high school teachers and students from underrepresented groups in local high schools.