Abstract
Several factors associated with the uniformity of electroless copper has been investigated. It was confirmed that the higher the aspect ratio, the lower the uniformity of the deposition. It is because as hole diameter decreases and aspect ratio increases the amounts of hydrogen gas trapped in through-holes in the boad increases. Inclinating or vibrating the boad is an effective way of reducing the amount of trapped gas and improving deposition uniformity. Deposition uniformity was also increased by decreasing the concentration of the dissolved oxygen in the bath. This is related to the surface activation of deposited copper by the dissolved oxygen. The EDTA concentrations in the plating bath also influenced deposition uniformity. Uniform copper obtained when EDTA concentrations were increased.
