Fabrication and characterization of micro-sized copper bump of multi-layer PCB by pulse-reverse electroplating

Abstract

In this research, micro-sized copper bump for multi-layered printed circuit board (PCB) was successfully developed using pulse-reverse electroplating method. The electroplating parameters of current density, pulse-reverse ratio and brightener content were optimized for fabrication of suitable micro-bumps. The pulse-reverse electroplated micro-bumps were characterized using various analytical tools and techniques such as optical microscopy, scanning electron microscopy, atomic force microscopy and hydraulic bulge testing. Optical microscope and scanning electron microscope analysis results indicated good electroplating uniformity in the current density range of 1.4–3.0 A/dm 2, pulse-reverse ratio of 1:1, and brightener concentration of 600 ppm.