Substrates with ultra fine pitch flip chip bumps

摘要

A method of attaching a chip to the substrate with an outer layer comprising via pillars embedded in a dielectric such as solder mask, with ends of the via pillars flush with said dielectric, the method comprising the steps of: (o) optionally removing organic varnish, (p) positioning a chip having legs terminated with solder bumps in contact with exposed ends of the via pillars, and (q) applying heat to melt the solder bumps and to wet the ends of the vias with solder.