Fabrication of various dimensions of high fill-factor micro-lens arrays for OLED package

Organic light-emitting diode (OLED) has been the subject of much interest in the lighting and display module. This study focuses on how to enhance brightness and scatter through a micro-lens array (MLA) with high fill-factor. A LIGA-like (Lithographie Galvanoformung Abformung, LIGA) process was applied to the fabrication process because it has good replication for microstructures. Seven kinds of micro-lens arrays with different dimensions were designed. These dimensions with different aspect ratio were divided into two groups, i.e. gapless high fill-factor and low fill-factor with gap. They were used to compare their optical properties of brightness with each other. In addition, a controllable method was also developed to design the contour of a micro-lens. Then, a metallic mold with MLA was fabricated by nickel–cobalt (NiCo) electroplating process. A highly accurate and strong mold can be obtained. Finally, a UV (ultraviolet) curable polymer was used as the material of an optical film in this replication process of a MLA. After these optical films with MLAs were obtained, an optical microscope (OM) and a photometer were used to measure and characterize the optical results. The experimental results of the MLA were compared with those of the design.