Abstract: Through glass via (TGV) technology plays a vital role in advanced 3D integration and wafer-level packaging. However, the significant mismatch in the coefficient of thermal expansion (CTE) between Cu and glass wafers often leads to reliability issues such as delamination, cracking, and warpage during thermal cycling. To address this challenge, we innovatively propose using a Ni-Fe alloy as a novel TGV filling material. By optimizing the NiSO₄/FeSO₄ concentration and additives in the electrolyte, a Ni-Fe alloy with a CTE of 7.27 × 10^-6 K^-1 was obtained, closely matching that of the glass substrate (7.2 × 10^-6 K^-1). With electrodeposition technology, we successfully achieved void-free filling for TGV with Ni-Fe alloy. Compared with traditional Cu-filled TGV, Ni-Fe alloy-filled TGV demonstrated significantly improved CTE mismatch and thermal stability, showing its great potential for next-generation glass-based advanced packaging.

Key words: Ni-Fe alloy, Through glass via, Superfilling, CTE mismatch, Thermal reliability