Study on the replication accuracy of polymer hot embossed microchannels

Microfabrication of polymers is becoming increasingly important and considered as low-cost alternative to the silicon or glass-based microelectromechanical systems technologies. However, most of hot embossing studies were done on thin films that may not fulfill the structural requirements of the products. In this study, micromolding via hot embossing was applied to microfeatured fluidic platform used for DNA/RNA test. The microfeature in the stamp of 127 mm diameter and 0.22 mm thickness includes microchannel array of approximately 30 μm in depth and 50 μm in width. A PMMA film of 1 mm thickness was utilized as molding substrate. In this work, the effects of molding conditions on the replication accuracy of microfeatures were investigated. In addition, the replication accuracies of microfeatures at various stamp positions due to the effects of density of microchannel, constraint condition, and normal pressure distribution were also discussed. The imprint width and depth of microchannels were analyzed and correlated. It was found that applied load, embossing temperature, and embossing time all significantly affect the molding accuracy. The accuracies of the imprint depth and width increase with the embossing load, temperature, and time until the associated dimensions reach saturated values. Basically, 18 kN applied force and 135 °C embossing temperature provided acceptable results considering reasonable cycle time. Regarding the effects of positions on the imprint replication accuracy, we found that closer to the center of molded parts produces better replication accuracy.