A new bonding process for polymer micro- and nanostructures based on near-surface degradation

A new approach to bond polymer micro- and nanostructures has been developed which avoids many problems caused by adhesives, solvents or high temperatures. The new process is based on generating a thin surface layer with a lowered glass transition temperature in a thicker polymer bulk layer with a higher glass transition temperature by near-surface degradation of the thermoplastic polymer. So welding or heat-sealing is possible at low temperatures. Because of the low thermal load, even bulk structures in the range of some few micrometers and with structure details in the submicron range remain dimensionally stable. The new bonding strategy is demonstrated using the example of a process on the basis of photodegradation. Moulded polymethylmethacrylate (PMMA) microchannels and microspectrometer reflective gratings were bonded to PMMA cover plates by ultraviolet irradiation of the joining faces and subsequent welding at low temperatures. With this new process, celluloseacetate film samples were successfully bonded also.