Adhesion phenomena pertaining to thermal interface materials and solder interconnects in microelectronic packaging: A critical review

High performance and diverse power computing needs in desktop, server, communication, automotive, and artificial intelligence microelectronic sectors demand microprocessors with different form factors and intricate package designs. For such complex package architectures, semiconductor chips in addition to microprocessor, such as in-package memory, transceivers or a combination of both are essential to attain maximum performance. Integrated Heat Spreader (IHS) assembly with thermal interface material (TIM) layers plays a vital role in providing heat dissipation for these integrated circuit chips and aids them to perform with maximum efficiency for a long duration. Additionally, for Ball Grid Array (BGA) semiconductor packages, interfacial adhesion quality of solder attach material is very critical in determining package quality and reliability. There are numerous challenges associated with developing and optimizing such an IHS assembly process and solder attach material for high volume manufacturing with good throughput, quality and yield. Here we provide a comprehensive review of the adhesion mechanisms and challenges of polymer TIMs to IHS-metal interface and various techniques proposed in the literature to enhance their adhesion. Complexities involved in solder attach adhesion including material selection and chip assembly interaction are reviewed in detail as well.