Effects of 2,2′‐Dipyridyl on Electroless Copper Deposition in the Presence of Excess Triethanolamine

With the addition of 2,2'‐dipyridyl to the triethanolamine (TEA) electroless copper bath, the effects on the deposit quality were examined. While the optimum deposit quality in the ethylenediaminetetraacetic acid (EDTA) bath was obtained by adding 2,2'‐dipyridyl, the optimum quality for the TEA bath was obtained by adding higher than 2,2'‐dipyridyl. We analyzed the difference in the optimum concentrations between the EDTA and TEA baths based on the adsorption model and found that 2,2'‐dipyridyl in the TEA bath adsorbs onto the adsorbed Cu(II)‐TEA complexes. On the other hand, in the EDTA bath 2,2'‐dipyridyl adsorbs on the naked surface. The difference in the required concentration of 2,2'‐dipyridyl to attain the optimum deposit quality between the TEA bath and the EDTA bath is interpreted by the differences in the adsorption equilibrium constants of excess ligand.