Hybrid Soldering 2.3D Assembly With High Reliability and Low Cost

In this study, an advanced 2.3D solution was proposed to integrate RDL interposer and FR-4 substrate using the technique of hybrid soldering, which applies printing of epoxy solder paste to form the hybrid joint. The simulation was performed to evaluate warpage and von Mises stress of different joint structures, indicating that the hybrid joint structure is promising for the reliability of 2.3D assembly. In addition, hybrid soldering 2.3D assembly was successfully demonstrated, followed by SEM analyses, electrical measurements, warpage measurements, and thermal cycling tests for 5000 cycles. The experimental results validate that the packaging can achieve high reliability without the needs of underfill. Thus, this solution paves the way for large area 2.3D integration with low cost, high throughput, and high reliability.