Patent ID: 8492262

Claim:
A method comprising the steps of: obtaining an assembly comprising: a substrate; a plurality of wet-able pads formed on a surface of said substrate; and a solder resist layer deposited on said surface of said substrate and having an outer surface, wherein at least said solder resist layer is formed with recessed regions defining volumes adjacent said wet-able pads, wherein a recessed region includes a straight region extending perpendicularly with respect to a top surface of an adjacent wet-able pad, and an inclined region extending from the straight region at an oblique angle with respect to the straight region; directly injecting molten solder into said volumes adjacent said wet-able pads, such that said volumes adjacent said wet-able pads are filled with solder; allowing said solder to solidify, whereby said solder forms a plurality of solder structures adhered to said wet-able pads; and re-heating said substrate and said solder after said solidification, to re-flow said solder into generally spherical balls extending above said outer surface of said solder resist layer; wherein said volumes adjacent said wet-able pads are configured and dimensioned to receive sufficient solder in said injecting step such that said generally spherical balls extend above said outer surface of said solder resist layer as a result of said re-heating step.