| Abstract Scope |
In recent years, packaging has evolved from 2D to 3D stacking, with 2.5D/3D advanced packaging enabling heterogeneous chiplet integration for improved performance and reduced costs.Although CoWoS is a key technology, its high-temperature processes pose thermal budget limitations, risking damage to heat-sensitive components and interposer cracking or warpage.
Sn-Bi solder, with a low melting point and lower cost, is a promising material for large-scale low-temperature bonding applications. In this study, we developed a slurry containing Sn58Bi solder powder and fluxing epoxy resin. During the reflow process, solder droplets self-assemble to form solder joints, then epoxy resin surrounding formed solder joints cures to serve as underfill. This process achieves flip-chip bonding and underfilling in single step, and we term this new material Self - Assembly Sn Epoxy (SASE), offers a low-temperature solution that reduces thermal stress, improves reliability, and supports future heterogeneous integration and miniaturized packaging |