Processing Tank Flow Mechanics for Next Generation Glass Core Substrates

Glass substrates are increasingly seen as an alternative for interposers in heterogeneous packaging [1]. In a typical wet tool, substrates undergo chemical treatments in separate tanks. Standard panels (510x515mm) are processed simultaneously, requiring a carrier for automated loading, unloading, locking, and transportation. This study examines flow velocities between panels, carrier walls, and tank walls in stationary positions. The overflow tank, a crucial sparger system component, has three fluid parts: the lower distribution area, a separation plate, and the main tank. To enhance the design, we study the interplay between porous resistances, showerhead coverage, carrier-to-platform distance, carrier-to-free surface distance, carrier-to-wall gaps, and distances between panels. Our approach aims for a custom flow field in the sparger tank that is as uniform and unidirectional as possible. Designing tank and carrier components to prevent stagnation zones ensures shorter residence times, critical for the sparger system’s effectiveness. Our findings apply to wet chemical etching of TGV vias or electroless metal (Ni, Cu, etc.) deposition processes.