Coreless packaging substrate and method of fabricating the same

摘要

A coreless packaging substrate is provided which includes: a circuit buildup structure having at least a dielectric layer, at least a wiring layer and a plurality of conductive elements, a plurality of electrical pads embedded in the lowermost one of the at least a dielectric layer, a plurality of metal bumps formed on the uppermost one of the at least a wiring layer, and a dielectric passivation layer formed on the surface of the uppermost one of the circuit buildup structure and the metal bumps, with the metal bumps exposed from the dielectric passivation layer. The metal bumps each have a metal column portion and a wing portion integrally connected to the metal column portion, such that the bonding force between the metal bumps and a semiconductor chip is enhanced by the entire top surface of the wing portions of the metal bumps being completely exposed.

主权项

1. A coreless packaging substrate, comprising:
a circuit buildup structure having at least a dielectric layer, at least a wiring layer formed on the at least a dielectric layer, and a plurality of conductive elements formed in the dielectric layer and electrically connected to the at least a wiring layer; a plurality of electrical pads embedded in a lowermost one of the at least a dielectric layer for electrically connecting part of the conductive elements, wherein the electrical pads are exposed from a surface of the lowermost one of the at least a dielectric layer; a plurality of copper bumps formed on an uppermost one of the at least a wiring layer, and each having a copper column portion and a copper wing portion integrally formed on the copper column portion, wherein the copper wing portion of each of the copper bumps is greater in diameter than the copper column portion; and a dielectric passivation layer formed on an uppermost one of the at least a dielectric layer, the uppermost one of the at least a wiring layer, and the copper bumps, with an entire top surface of the copper wing portion of each of the copper bumps exposed from the dielectric passivation layer, wherein the exposed top surface of the copper wing portion of each of the copper bumps directly contacts and is electrically connected with solder bumps of a semiconductor chip, the dielectric passivation layer is the same in width as the uppermost one of the at least a dielectric layer, and the copper bumps are free from protruding from the dielectric passivation layer.