Acoustic-streaming driven liquid filling patterns inside through-glass vias

Abstract

Filling through-glass vias (TGVs) with liquid remains a significant challenge in IC packaging technology. This study presents an acoustic-streaming method to modulate the wetting behavior as well as the interfacial dynamics to fill the TGVs. We categorize the incomplete filling into three typical patterns: (a) neck wetting, (b) head and end wetting, and (c) bubble wrapping. Experimental results show that the ultrasonic driving at 522.5 kHz/160  V can effectively achieve ideal filling of these patterns in TGVs (aspect ratio of 1:2/1:3). The filling processes are elucidated from a new perspective: the liquid flow induced by acoustic streaming regulates the moving of contact line to complete wetting on sidewalls, while the acoustic wave impacts the gas–liquid interface to cause oscillations for pushing bubbles out. A Lattice Boltzmann model is constructed to reveal the mechanism. This method offers a viable and promising solution to promote liquid filling of TGVs.