Studies of acid sulfate copper pulse reversal current electrodeposition

Copper electrodeposition is a crucial process in the fabrication of high density build-up multilayer printed circuit boards (PCBs), thus the effects of additives and plating waveforms would provide useful information for future production of PCBs, The effect of additives AC90 and chloride ion on the redox potential and polarization resistance of copper electroplating were evaluated. This revealed an interesting synergistic effect of chloride ion and additive AC-90 with a substantial increase in the polarization resistance. Moreover, copper electrodeposition obtained by direct current, periodic pulse current and periodic pulse reversal current plating in the presence and absence of additive AD-90 were investigated. The thickness, surface morphology, texture, elongation percentage and tensile strength of the copper deposits were evaluated, The copper electrodeposit obtained by periodic pulse reversal current plating exhibited the best macroscopic throwing power among the three protocols based on thickness studies. The X-ray diffraction pattern of this copper deposit was a non-textured random deposit. In addition, this deposit showed desirable properties when compared to Class I copper foil (percent elongation 5.20 %; tensile strength 20.34 kgf/mm(2)). With the presence of additive AC-90 in the plating solution, the microscopic throwing power of the copper deposit is improved and a smooth surface morphology of copper deposit was obtained, Copper electrodeposits obtained by periodic pulse reversal current plating would therefore be ideal for future manufacturing of PCBs.