A Versatile Fan-Out Infrastructure Based on Die-Stencil Substrate Promoted by an Advanced Multifunctional Temporary Bonding Material

The development of new advanced packaging technologies is always in high demand due to the continuous pursuit of smaller package sizes, higher performance, more integration of functionalities, lower power consumption, and reduced cost of ownership. As a result, various advanced packaging platforms have been established, such as flip chip, fan-in wafer-level packaging, fan-out wafer-level packaging, embedded die, and through-silicon via (TSV). Among them, fan-out wafer-level packaging (FOWLP) is quickly gaining prominence, especially in high-end use and for providing an efficient solution for system-in-package (SiP) and 3D integration. However, there are several well-known disadvantages of the traditional FOWLP process, such as die shift during molding, large warpage due to coefficient of thermal expansion (CTE) mismatch, time-consuming molding and curing processes, and outgassing and low thermal stability of epoxy resin. Therefore, people are seeking alternatives for existing FOWLP solutions, such as embedded silicon fan-out (eSiFO) and glass fan-out (GFO) packaging. In this paper, we will introduce a new versatile fan-out packaging structure as an alternative solution for the traditional FOWLP. This new emerging technology is based on a polymeric die-stencil substrate, in which cavities are created by laser ablation or by mechanical means to accommodate different dies. There are several advantages of this new FO packaging platform: 1) more flexibility on choice of polymeric die-stencil substrates in order to achieve optimized performance; 2) ease of configuration of stencil to accommodate different die sizes, especially for fabrication of SiP; and 3) improved throughput by eliminating the time-consuming molding and curing process in traditional epoxy resins. In addition, we will introduce new multifunctional materials that are under development specifically to facilitate the demonstration of this new stencil-based FO technology.