Abstract
Laser beams have a vast range of applications, from optical drives for CDs and DVDs, to large scale laser cutting and drilling processes. Lasers have also been used in the past for surface modification of materials, and laser ablation mechanisms. This work focused on two regimes of laser power intensity, using a Nd:YAG nanosecond pulsed laser for lower power intensity and a picosecond pulsed diode pumped Yb-doped fibre laser for higher power intensity. Using the lower power intensity, studies were undertaken on the surface modification of PP and PEEK material, intended for increased adhesion strength of the materials bonded together in a lap shear configuration. Treated surfaces were examined by CLSM, contact angle analysis, FT-IR, XPS, and ToF-SIMS, and were tested in single lap shear tests. It was found that laser surface treatment improved the surface energy (44.9 mJ m-2 to 72.5 mJ m-2 in the case of PEEK and 32.5 mJ m-2 to 57.5 mJ m-2 in the case of PP) and wettability of the treated surfaces. This lead to improved adhesion strength in the lap shear tests. The higher power intensity provided by the picosecond pulsed laser was used to strip the active layers and coating materials from photovoltaic fibres and energy storage fibres with a copper core conductor, with the intention of exposing the copper for subsequent electrical interconnection. The treated samples were examined by focus variation microscopy, SEM, XPS and electrical continuity measurements. It was found that the coatings could be successfully stripped using a wavelength of 532 nm, pulse repetition rate of 100 kHz, 2 passes, a sample angle of 90°, and a scanning speed of 100 mm s-1. This exposed the copper conductor and maintained electrical continuity.