Process for selective application of solder to circuit packages

Abstract

Small, closely spaced deposits of solder materials may be formed with high volumetric accuracy and uniformity of shape by depositing a layer of conductive material over surfaces of a dielectric layer having apertures or recesses (e.g. blind apertures) and conductors and/or pads exposed by those apertures or recesses, masking regions of the conductive material with a further patterned dielectric layer, electroplating solder materials onto regions of the conductive material exposed by the mask, removing the mask and portions of the conductive material by selective etching and reflowing solder away from at least a portion of the surfaces of the apertured dielectric layer. Uniformity of electroplating within blind apertures is enhanced by a combination of fluid jet sparging and cathode agitation. Excess conductor material in the resulting solder deposit can be avoided by replacing conductor material with a constituent component of a solder material in an immersion bath prior to electroplating.

Dependencies are inferred from the claim text.