This paper will discuss a simple methodology for patterning metal tracks onto the polymeric substrate polybutylene terephthalate (PBT). The selective metallization process consists of three main steps: (1) surface patterning and activation with picosecond-laser pulses in a dry processing environment; (2) treatment of the substrate in PdCl2 seeding solution, and (3) selective metallization of the substrate via electroless copper deposition. It was found that, besides a significant surface roughening, the use of ultra-short laser pulses promoted the chemical modification of the polymeric surface in a manner that the surface acquires the ability to reduce Pd-ions into metallic Pd clusters during a subsequent treatment in PdCl2 solution. The laser parameters as well as the concentration and the temperature of the PdCl2 solution were investigated and correlated with the surface morphology, the formation of Pd clusters as well as with the characteristics of the copper layers. The copper features were homogeneous and exhibited well defined geometries. Moreover, the adhesive properties of the copper structures were investigated. Tape tests showed that the copper structures exhibited good adhesion to the PBT substrate and this is ascribed to the high roughness obtained via laser patterning. The copper layers exhibit low electrical resistivity values and therefore show great potential for applications in electronic devices even with 3D complex geometries.
References:
[1] J.H.-G. Ng, M.P.Y. Desmulliez, M. Lamponi, B.G. Moffat, McCarthy, H. Suyal, C. Walker, K. Prior, D.P. Hand, A direct-writing approach to the micro-patterning of copper onto polyimide, Circuit World. 35 (2009) 3–17.
[2] M. Huske, J. Kickelhain, J. Muller, G. Eber, Laser supported activation and additive metallization of thermoplastics for 3D-MIDs, Proc. 3rd LANE. (2001) 1-12.
[3] J. Zhang, T. Zhou, L. Wen, Selective Metallization Induced by Laser Activation: Fabricating Metallized Patterns on Polymer via Metal Oxide Composite, ACS Appl. Mater. Interfaces. 9 (2017) 8996–9005.