A new process combines patented Branson Simultaneous Through-Transmission Infrared (STTIr) laser welding technology from Emerson with ultrasonic spray deposition technology from Sono-Tek to make laser welding of “clear-on-clear” plastic parts possible.
This innovation offers new design possibilities for the makers of medical devices, drug delivery systems and in-vitro testing products. Previously, laser-welded products were limited by the need to combine one “clear” or “transmissive” plastic part with a second “dark” or “absorptive” plastic part. The new process overcomes this limitation by precision-treating one of the clear mating parts with a bio-compatible laser absorber prior to laser welding. The use of the laser absorber means that the clear-on-clear welding capability can be a “bolt-on” upgrade to Branson laser welders that employ its STTlr technology.
The new process delivers cycle times measured in seconds, making laser welding of medical-quality clear-on-clear microfluidic parts economically viable. It also allows for a greater range of clear thermoplastic parts to be bonded, regardless of chemistry. The laser-absorbing pigment dye generates and conducts heat and melt and can compensate for even large differences in the glass transition temperature (Tg) of different clear polymers used in mating parts.