Direct joining of a laser-ablated metal surface and polymers by precise injection molding

The joining of metal and polymer surfaces is a promising technology to reduce the total weight of parts and to improve interface reliability. In this study, a micro square grid (200 μm × 200 μm) was fabricated on an aluminum surface using laser ablation. Molten glass-reinforced poly(butylene terephthalate), poly(styrene) and acrylonitrile–butadiene–styrene were introduced to the micro square grids by a precise injection molding machine. The maximum load tensile test was used as a measure of the joining strength between aluminum and the polymer. The tensile strength tests assisted in the differentiation of three modes of separation: interface-peeling, cohesive failure and matrix fracture. The maximum load increased with the effective joined area where interface-peeling was observed. The maximum load ceased at a certain effective joined area, and matrix fracture occurred. Cohesive failure was observed where the effective joined area was smaller than the area for which matrix fracture was observed, and the joined strength was larger than that observed for interface-peeling. The maximum stress, which was calculated by dividing cross-sectional area by the maximum load, at the matrix fracture was proportional to the polymer tensile strength.