Through-hole (TH) filling of a printed circuit board (PCB) was conducted with a copper electroplating solution. Tetranitroblue tetrazolium chloride (TNBT) was used as an inhibitor and acetic acid electrolyte instead of a traditional H2SO4 electrolyte was used for the copper electroplating. Moreover, functional insoluble anodes (DT) that were activated with iridium-based mixed metal oxides on Ti meshes were used instead of conventional soluble anodes (i.e., P-doped Cu). The TH filling performance of the copper electroplating solution was significantly enhanced when acetic acid electrolyte and DT anodes were used simultaneously in the copper electroplating bath. (C) 2013 The Electrochemical Society. All rights reserved.