Electroplating solder-bump connectors on microcircuits

Claim 1

The steps in a method of forming bumps of solder on terminal areas of integrated circuit chips for mounting said chips on carrier modules and for connecting the circuits of said chips to conductors of said carrier modules, which steps comprise a. applying a glass coating to a silicon wafer having a plurality of circuits thereon distributed suitably for the fragmentation of said wafer into chips, each having a circuit and terminals, said glass coating covering said circuits and terminal areas, b. forming openings in the glass coating to expose said terminals, c. forming openings in said glass coating to expose areas of the silicon of said wafer at positions between the chips-to-be, d. depositing over said wafer a conducting layer of contact metal suitable for making adherent conductive connections to said terminals and to said silicon at said interchip areas, said metal layer covering said glass coating and forming electrically conductive bonds to said terminals and to the silicon exposed at said interchip areas, e. covering said layer of contact metal with a masking layer of electroplating resist and providing openings therein over said terminals for exposing said contact metal, f. applying an electric connection to the silicon of said wafer for thereby obtaining good electric conduction to said terminals of each chip through said silicon and through the bonds of said contact metal to the silicon at said interchip areas, g. utilizing said connection for electroplating solder onto the parts of said contact metal layer over said terminals so exposed through the openings in said resist, h. removing said resist and removing the then exposed, unplated parts of said contact metal layer, and i. heating the electroplated solder on said terminals to cause said solder to contract into a rounded bump on each terminal.