적외선 예열을 이용한 롤-투-플랫 텍스쳐링 시스템 개발과 공정 변수의 연구

Abstract

Manufacturing technology of nano/micro structure has been utilized since theinformation technology and the bio technology increased its importance in these days.Thermoplastic materials have been used in mass production of nano/micro structurebecause of their various characteristics and low cost. Roll type texturing, one ofthermoplastic mass production method, has simple characteristics of continuous andone-step process which Rolling cylindrical mold on the thermoplastic substrate withproper pressure and temperature. However, this method does not have any specificcooling process which setting textured structure under glass transition temperature.The absence of cooling process causes recovery or reflow problem, so the texturedstructure shows distortion of its shape. That bad transcription quality with respect tothe roll mold increases with height of the structure of the mold. In case oftranscribing structures with height bigger than 100 μm, the transcription quality ofdepth decreases to less than 60%. However, structures more than 100 μm depth areapplied to IT or BT technologies, for example microfluidic devices. To increasetranscription quality of micro structure and apply to microfluidic devices, 3 objectiveswere set in this study, 1) Development of Roll-to-Flat system to increase transcriptionquality, 2) Processing parametric study and optimization with Taguchi method, 3)Application to the fabrication of microfluidic device. Roll-to-Flat system wasdeveloped with components: roll mold, cartridge heater-temperature controller,pneumatic cylinder, and step motor based 1-axis actuator. For the fast heating andcooling of the thermoplastic substrate, Infrared preheating system was applied toRoll-to-Flat system. Infrared preheating system showed surface temperature differenceof the substrate with before and after of the roll mold contact, and increase of thetranscription quality. Four main controllable processing parameters

roll moldtemperature, pressure of pneumatic cylinder, speed of 1-axis actuator, surfacetemperature of the preheated substrate, were studied experimentally. For the efficientstudy, L9 (34, 4 paramters, 3 levels) orthogonal array based Taguchi method wasused. Optimization of transcription quality and processing parameters was estimatedwith Taguchi method, and its reliability was tested by experiment. As a applicationof developed Roll-to-Flat system, microfluidic devices were fabricated and itsfeasibility was tested with microfluidic experiment.