Conductive polyaniline film synthesized through in-situ polymerization as a conductive seed layer for hole metallization of printed circuit boards

Abstract

At present, the electroless copper is widely used to achieve the hole conductivity in printed circuit boards (PCBs), but this process contains carcinogenic formaldehyde and uses the precious metals for activation. Here, the conductive polyaniline as a seed layer of PCB is attempted to achieve the hole metallization. The polyaniline is formed on the hole through an in-situ oxidation polymerization method. The formation process of polyaniline was analyzed by SEM, FTIR, and XPS and an uniform polyaniline film with spherical cluster is revealed. The deposition behavior of copper on the polyaniline layer is analyzed by the LSV and Tafel where the deposition potential of Cu is about −0.18 V. The filling tests showed that the copper super-filling can be achieved on the polyaniline layer and the filling time is about 150 min and 90 min for the blind hole with a depth to width ratio of 0.75 and of 0.67, respectively. Thermal shock experiments showed that the copper layer on the polyaniline has good adhesion. These results demonstrate that the polyaniline can serve as an effective seed layer instead of the electroless copper to achieve the hole metallization, which provides a new solution for exploring friendly hole metallization processes for PCB.