Microstructure for Zero Void by Control of Cu2+ in Metallization for TGV of Glass Core Substrate

초록

Metallization of glass core substrates by electroplating has produced four types of defects: internal voids, internal underfilling, deep dimple, and protrusion of various sizes. To identify the cause of internal voids, the most difficult of the four defects to eliminate, microstructural analyses of Cu in TGV (Through Glass Via)s with and without void were conducted using Electron Backscatter Diffraction (EBSD) and Scanning Electron Microscope (SEM). The crystallographic orientation distribution, grain size, aspect ratio, and Grain Orientation Spread (GOS) of the Cu microstructure were investigated in the area from the TGV entrance to 25% of the total TGV depth and in the central area where the void was generated. One of the most significant differences observed between the entrance and central areas was the grain size distribution. It was found that reducing grain size in the entrance area compared to the central area was essential for controlling internal voids. Since the mobility of Cu2+ metal ion in the Cu electroplating solution is limited, it is very difficult to achieve the desired balance between the depletion and supply rates of metal ions in the entrance and central areas of TGV. To achieve this balance, factors such as the anode-substrate distance, cathode contact distribution, current conditions (pulse and reverse), and additives have been optimized. © 2026 IEEE.

키워드