1、Hot Embossing Microfabrication,Hot Embossing is a technique of imprinting microstructures on a substrate (polymer) using a master mold (silicon tool).,Steps in Hot Embossing,Heating Silicon & Polymer above glass transition temperature (Tg). Applying load by pressing the silicon tool on polymer at ce
2、rtain embossing pressure. Cooling the silicon tool and polymer assembly below Tg and de-embossing the tool.,Advantages of Hot Embossing System,Cost effective Easy manufacturability. Time efficient Fast process. Fabrication of high aspect ratio features. Bio-Compatible surfaces Polymer substrates use
3、d. Disposable Low cost for volume production.,Applications of Hot Embossing,BioMEMS/Bio-Sensors Micro-Fluidic Devices Micro-Optics m-TAS (Micro Total Analysis Systems),Hot Embossing v/s Other MEMS Fabrication Processes,Product Comparison,Schematic Representation of Hot Embossing Setup,Hot Embossing
4、Conceptual Solid Models,Heating Subsystem: Thermal Analysis,Heating block dimensions and number of cartridges found by a parametric study. 53 heating cartridges (1 kW, 1/2”, 10” long) on each heating block of 10” (L) x 10.5 (B) x 4” (H).,Appropriate zone configuration of heating cartridges for optim
5、al heating time, prevention of hot spots, and uniform heating on mold and substrate surfaces. 5 heating zones per heating block having different heating power/heat flux.,Heating Subsystem: Thermal Analysis (Cont),Zone Configuration obtained using iterative transient FEM thermal analysis in ANSYS. Tr
6、ansient behavior of heating cartridges also taken into account.,Heating Subsystem: Thermal Analysis (Cont),Forcing Subsystem: Structural Analysis,Forcing System used to provide embossing force. Forcing provided by a Dual Column Floor Mounted Frame material testing system by Instron Corporation model
7、 5800. Thermal solution incorporated for FEM structural analysis. Material modeling incorporates Youngs modulus and Poissons ratio variation with temperature.,Displacement contour plot from structural analysis,1/4th model used for finite element analysis due to symmetry.,Forcing Subsystem: Structura
8、l Analysis (Cont),Cooling Subsystem,15 Ton (52.76 kW) chiller and Temperature Controller used to cool the system within 2 minutes. Cooling plates divided into 5 zones (5 inputs, 5 outputs) to obtain uniform temperature distribution on the mold and substrate surfaces. optimize cooling time. Manifolds
9、 and flow-meters used to evenly distribute the cooling oil into the cooling plates.,Mini-Vacuum Chamber,Mini vacuum chamber used to provide a clean and moisture free environment during embossing. Mini vacuum chamber can accommodate an 8” substrate.,Control Subsystem,Compact Fieldpoint system and Lab
10、VIEW by National Instruments used for data acquisition and control of the main system and individual sub-system.,LabVIEW is used to: Monitor the chiller set-points, the temperature across the master and the substrate, the pressure in the vacuum chamber. Control the motion (displacement and velocity) of the embossing machine, the flow of the cooling oil through the cooling block, the current through the heater cartridges relief valve of the vacuum chamber.,Control Subsystem (Cont),
