Effects of Plasma Treatment on Adhesion and Flow Behavior of Underfill in 2.5D Electric Package

Plasma surface treatment technology is widely used in IC packaging industry to enhance the process performance and reliability of underfill. This study investigates the effect of plasma treatment on filling time, void count and flow mark of the underfill in 2.5D package. The filling time of underfill in a dummy TV obtained a reasonable score of 12 min 15 s at 200 s plasma treatment, and the void and flow mark in this dummy TV were significantly improved after this plasma treatment. Meanwhile, the effect of plasma treatment on the interfacial adhesion strength of underfill on PI-coated RDL-interposer was investigated. The interfacial adhesion strength between underfill and PI-coated RDL-interposer peaked with 200s plasma treatment at room temperature, 260 °C and after PCT. The morphology and composition of the untreated and plasma-treated PI-coated RDL-interposer were characterized to investigate the effect of plasma treatment on surface of PI-coated RDL-interposer. This study will aid the optimization of plasma treatment condition to improve the processibility and reliability of underfill, thus increasing the reliability of the 2.5 D package with PI-coated RDL-interposer.