Cu deposition technologies for build-up film substrates towards FC-BGA

In recent years, technologies concerning flip chip ball grid array (FC-BGA) substrates with the circuitry of narrow line/space have witnessed significant developments, which are fabricated on build-up films (BFs) via the semi-additive process (SAP). A variety of factors including microstructures, physical and chemical features of build-up films, copper deposition parameters and relevant chemical bath compositions collectively determine the resolution and bonding strength of fabricated circuitry and ultimately affect the quality and reliability of packaging substrates, which makes it meaningful to study and reveal the relevance of these factors. Based on the fabrication technologies of copper interconnects in build-up film substrates towards FC-BGA, this review puts emphasis on the discussion of copper plating bath compositions in the semi-additive process on build-up films, and outlooks possible future prospects of further increasing the quality of circuitry, in accordance with some key evaluation factors of deposited copper.