In this paper a method of Laser surface smoothing of 3D printed polymer material based on a nanosecond Laser is introduced. The adequate Laser enabled reducing surface roughness by 65% on a 25x25 mm² surface and therefore improving the printing quality of metal layer deposited on top to fabricate HF passive devices. This paper also examines the impact of Infrared (IR) sintering combined with thermal treatment in order to improve the electrical conductivity of printed silver layers by micro dispensing technique (nScrypt technology) up to 30.5 S/µm. A patch antenna was printed on smoothed PEEK substrate and gave promising results (gain of 5.4 dBi @ 6.8 GHz).