FILLING THROUGH-HOLES

摘要

Pulse plating methods which include a forward pulse but no reverse pulse inhibit or reduce dimpling and voids during copper electroplating of through-holes in substrates such as printed circuit boards. The pulse plating methods may be used to fill through-holes with copper where the through-holes are coated with electroless copper or flash copper.

主权项

1. A method comprising:
a) providing a substrate with a plurality of through-holes comprising a layer of electroless copper, copper flash or combinations thereof on a surface of the substrate and walls of the plurality of through-holes; b) immersing the substrate in a copper electroplating bath comprising an anode; and c) filling the through-holes with copper by a pulse plating cycle consisting of applying a forward current density for a predetermined period of time followed by interrupting the forward current density for a predetermined period of time and applying a second forward current density for a predetermined period of time and interrupting the second forward current density for a predetermined period of time and optionally repeating the cycle.