Influence of Laser Parameters on the Activation of Cr₂O₃-Doped ZTA Ceramics for Selective Electroless Copper Plating in the Manufacture of 3D Ceramic Circuit Carriers

Due to the superior thermal, mechanical and chemical properties of ceramics, metallized ceramics are widely used as circuit carriers and interconnect devices wherever standard polymer-based circuit boards come to their limits. 2D metallization represents the current state-of-the-art. The metallization of 3D shaped ceramics cannot be achieved with standard metallization techniques and is still a field of research. In this study laser induced direct metallization (LDM) is applied, where a pulsed laser is used to locally activate the surface of a Cr₂O₃ doped ZTA ceramic. Subsequently a selective electroless copper plating on the laser irradiated areas is performed. Laser power, pulse repetition frequency, pulse overlap and the amount of surpasses were varied systematically in order to determine the parametric sensitivity of the ablation and metallization behavior for pulsed infrared laser structuring. It was found that ablation is necessary for the metallization and the peak fluence is the governing factor for the ablation and metallization process. It was further shown, that the ablation can be well predicted with an accumulated fluence which includes the pulse overlap. 3D ceramic substrates were successfully metallized applying an optimized set of laser parameters.