IMS (injection molded solder) with two resist layers forming solder bumps on substrates

摘要

A photoresist layer is applied over a solder resist layer on a substrate such as a wafer. Openings in the solder resist and photoresist layers are filled with flux-free molten solder using IMS. The process is applicable to fine pitch applications and chip size packaging substrates. A protection layer may be employed to facilitate removal of the photoresist layer from the substrate. An oversized substrate including an adhesive layer on a peripheral area may be employed for providing greater adhesion of a dry film layer to the peripheral area of the substrate than the central portion thereof. The peripheral area is removed following IMS.