Micro-groove manufacturing via a femtosecond laser on optically clear adhesive films

Highlight • A smooth groove with low average roughness was fabricated on the surface of optically clear adhesives by femtosecond laser irradiation. • A novel inverted trapezoidal structure was proposed to replacing Gaussian distribution for the channel processing. • A new testing method with visual detection and micro-spheres was proposed to evaluate the tack performance of adhesives in micro-areas after laser irradiation. In this study, the femtosecond laser ablation of optically clear adhesives (OCAs) was carried out to machine a smooth groove for optoelectronic module and chip integrated manufacturing. A series of microstructures (holes, channels and grooves) were machined and investigated with different incident laser energies. To design an appropriate array period and inverted trapezoidal shape for the channels, a smooth groove with average roughness 5.7 μ m was machined. After processing, a new method with visual detection was introduced to evaluate the tack of micro-areas. The results illustrate that both the tack and transmittance of the films are decreased after laser irradiation. With quantitative analysis of FTIR spectra, a massive loss of chemical bonds (hydrogen radicals) leads to performance degradation at the macro level. The partial preservation of the C - O , C = O and - O H bond maintains the stability of the irradiated structure with a small tack and transmittance.