Fabrication of thin stencil with buffer reservoir utilizing the combination of AZ4620 and SU-8 electroplating molds

Abstract

Screen printing is one of the major techniques for producing printing circuit board (PCB) in electronic industry. However, it is difficult to produce small patterns using conventional screen printing technique due to the limitation of the woven mesh. This work successfully develops a novel process for fabricating ultra-thin stencil with a buffer reservoir utilizing the combination of AZ4620 positive photoresist (PR) and SU-8 negative PR as the electroplating molds. The developed ultra-thin stencil is 2.5 μm in thickness, which is much thinner than the typical thickness of the conventional stencils. The stencil is produced with nickel plating process with the hardness and tensile strength of 250 HV and 70 kgf/mm2, respectively. The printing result shows that the developed stencil capable to print high resolution and thin pattern. Good printing results will present in this paper. Silver paste line with the width of around 20 μm can be successfully printed on PET substrate. The method developed in this study provides a simple and low-cost way to produce high resolution metal stencil.