Patent ID: 9099345
Filing Date: 2015-08-04
Classification: H01L

Abstract:
1. A wafer level package (WLP) bump structure comprising: a copper pillar extending perpendicularly a first distance from a fabricated WLP silicon surface, the copper pillar comprising pillar sides and a distal portion that is distal from the fabricated WLP silicon surface, the distal portion comprising a copper surface; an encapsulant about the pillar sides and substantially covering the fabricated WLP silicon surface, the copper surface being recessed a first recess distance below an encapsulant outer surface; a layer of nickel metallurgically bonded to the copper surface, the layer of nickel having a nickel surface that is recessed a second recess distance below the encapsulant outer surface, the second recess distance less than the first recess distance, wherein a volume is defined between the nickel surface and the encapsulant outer surface; and an under ball metallic (UBM) metallurgically bonded to the nickel surface, the UBM comprising a first portion that occupies the volume between the nickel surface and the encapsulant outer surface and a second portion that extends beyond the encapsulant outer surface, covers the first portion of the UBM, and overlaps a portion of the encapsulant outer surface; and a solder ball attached to the second portion of the UBM, the solder ball overlapping an edge of the second portion of the UBM and contacting the encapsulant outer surface.