Characterization of flexible copper laminates fabricated by Cu electro-plating process

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology, texture, hardness, electrical resistivity and folding behavior was evaluated. To achieve Cu layers with similar thicknesses, the current density was varied in the range of 0.2–3 A/dm² and the plating time was controlled in the range of 0.5–7.5 h to compensate for the variation of the current density. The surface morphology, hardness, and folding behavior were characterized by atomic force microscopy, nanoindentation technique and Massachusett Institute of Technology folding endurance test, respectively. The X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases; however, the preferred orientation changed from (220) to (111) as the current density increased over 1 A/dm². In addition, it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased simultaneously. The electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000, which were comparable to those of commercial FCCLs.