Copper electroplating of PCB interconnects using megasonic acoustic streaming

In this research experimental and simulated analysis investigates the influence of megasonic (MS; 1 ± 0.05 MHz) acoustic-assisted electroplating techniques, with respect to the fabrication of through-hole via (THV) and blind-via (BV) interconnects for the Printed Circuit Board (PCB) industry. MS plating of copper down THV and BV interconnects was shown to produce measurable benefits such as increased connectivity throughout a PCB and cost savings. More specifically, a 700% increase of copper plating rate was demonstrated for THVs of 175 µm diameter and depth-to-width aspect ratio (ar) of 5.7:1, compared with electrodeposition under no-agitation conditions. For BVs, a 60% average increase in copper thickness deposition in 150 µm and 200 µm, ar 1:1, was demonstrated against plating under standard manufacturing conditions including bubble agitation and panel movement. Finite element modelling simulations of acoustic scattering revealed 1st harmonic influence for plating rate enhancement.