TWI and the University of Cambridge have created the world’s smallest weld in thermoplastic material. The research could satisfy industry calls for welds in plastics below 10μm.
A series of laser welded joints with widths of 1μm and channels of 5μm were demonstrated, but smaller welds of 0.5μm were also achieved, leading the team to believe that plastic components with a resolution below 1μm are possible.
Electron beam lithography was used to pattern a coating of infrared absorbent material on a base of PMMA.
The demonstrations also showed that there wasn’t excessive heating to the areas outside the weld lines. TWI also said that joint strength was ratified using larger scale samples.
TWI’s website explained that the team worked with the idea that using a laser absorber dye resist material could allow joints to be made between plastics. The project team studied the use of electron beam lithography to pattern the absorber and enable welds with a width smaller than 10μm, mimicking methods used to build microelectronic circuits. The challenge was to generate micro-channels and infrared absorber tracks at their edges simultaneously, and to seal the channels.
Until now, producing welds in plastics under 10μm has been made difficult by the resolution limit of an infrared laser. However, using both laser welding and electron beam lithography, the collaboration has created new applications for smaller analysis chips and electronic components.
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