Micro Hot Embossing Metal Mold For Microfluidic Chip Based On No Back Plate Growing Method

This paper presents a novel microfabrication technology of micro hot embossing metal mold - no back plate growing method. Micro metal mold is fabricated by low-cost UV-LIGA surface micro fabrication process using negative thick photoresist, SU-8. Different from other micro hot embossing molds, the micro mold with vertical sidewalls is fabricated by micro nickel electroforming directly on nickel substrate. Because of no back plate growing demand, time of nickel electroforming decrease greatly. This takes advantages not only short produce cycle and low cost, but also high precision of micro mold. Based on the micro nickel mold and automation fabrication system, high precision and mass-producing microfluidic chips have been fabricated. Uniformity of width and height of micro mold is discussed. Thermal expansion and swelling of SU-8 structure at high temperature and at room temperature have also been investigated in the paper. From the experiment results of thermal expansion and swelling, it can be seen that thermal expansion of SU-8 structure affects the width of micro mold after nickel electroforming considerably