Via filling is the process of filling the copper-plated holes, known as vias, on a printed circuit board (PCB) with either conductive or non-conductive material. This process serves several purposes to enhance the overall performance and reliability of the PCB. The primary objective of via filling is to prevent the entry of impurities into the vias, reducing the risk of contamination or corrosion and maintaining the integrity of the PCB. Additionally, filling the vias improves their mechanical strength, making them more resistant to stress and mechanical loads, which is particularly important in applications where the PCB may undergo vibrations or mechanical shocks.