Study On Ultrasonic Micro Welding And Embossing Technology Of Polymer Micro Devices

Polymer micro devices as new MEMS devices are facing rapid development dueto the excellent properties of polymer materials. Compared with traditionalsilicon-based MEMS devices, with the advantage of transparency, compatiable tochemical fluid, low cost and simple processing techniques, polymer substrate is abetter choise than silicon wafer to manufacture microfluidic chips, which can be usedto handle micro/nano liter fluids in the areas of life science, biochemistry, medicinescience and environment testing. At present, to further reduce the processing cost hasbecome a key factor affecting the application of microfluidic chips.Ultrasonic microwelding and embossing technology (8μ:() is a low cost and high efficientfabrication approach for polymer micro devices, the research on it has significantacdamic and application values.To improve the embossing quality and develop newfabrication techniques, this dissertation studies the forming mechanism of polymermicro structure in the process of ultrasonic welding and embossing, as well as thefabrication approaches of the polymer microfluidic chips, the polymer electronicboards and the polymer flow sensors. The following contributions have been made:Basd on the thermodanymic theory of thermoplastic polymer material and thecharacteristics of ultrasonic welding and embossing process, the heat generationmodel of polymer under ultrasonic load is established, which reveals the change ofthermoplastic polymer from solid state to liquid state in the ultrasonic welding andembossing process, the flow and filling mechanisem of the melted polymer, andtheforming reasons of the microstructure defects.A noval micro manufacturing technique called ultrasonic micro welding andembossing process using polymer foil stack as substrates is proposed, through thetheory analysis and experimental comparision, the structure of the embossing mold isoptimized; The replication accuracy of several enginnering polymer is experimentallystudied and compared under the same and different processing conditions byultrasonic welding and embossing; the influence of process parameters on embossingquality is investigated by orthogonal experiment.Considering the process characteristics of ultrasonic welding and emossing, newmold for microfluidic chip is designed and fabricated, the microfluidic chip based onPVC foil stack is ultrasonically embossed and bonded; A novel method for designingand fabricating embedded microfluidic chip is proposed and experimeantlly appoved;The micro-injection function of8μ:(for polymer micro device is exemplified by amicrofluidic chip connector, which enlarges the application of the8μ:(process. To fabricate polymer foil-based electronic board,8μ:(process is introduced toreplicate the metal pattern on polymer foil from thin metal foil, the effect onembossing quality of the electronic conductor from the mold, the metal foil, thepolymer foil substrate and process parameters are experimentally studiedand tested;the electrical interconnection between the conductor paths and electronic componentsis realized by Z axis conductive tape, which is realizedby ultrasonic welding process,thequality test proves the feasibility and effectiveness of this encapsulating method.Hot wire anemometer flow sensor and calorimetric flow sensor based on polymerfoil stack are fabricated using8μ:(process; the testing experiments define thetesting range of these sensors, which appove the low cost and high efficiency of the8μ:(process. Fine electronic path of50μP is ultrasonically embossed on thin hardpolymer foil, and successfully intergrated in polymer anemometer flow sensor as aheater and temperature sensor, which paves a low cost road to manufacture theintergrateed microfluidic chips.The above research achivements enrich the manufacturing mehod of polymermicro structure and expand the application range of8μ:(process; therefore, theyhave great significances on promoting marketization of the low cost microfluidicchips.