New inkjet tech can “print” LCDs
Researchers have managed to discover a new inkjet technology that can “print” LCDs thanks to silver nanoparticles,laying down wiring made out of silver nanoparticles via a customized inkjet printer. Currently, TFT manufacturing consists of the development of masks which are then used to generate a pattern for the wiring on the surface of the semiconductor. The entire process is wholly dependent upon the mask, which results in a slower turnaround time. This also means minor design changes are a no-no, since a new mask will have to be created from scratch. With printing technology instead, one will be able to introduce both speed and flexibility to TFT manufacturing although initial attempts have shown success on a limited level. Today’s TFTs require a wiring scale of approximately 2µm, but inkjet technology is not that matured yet as it is limited to ink drops on the order of picoliters, which is ultimately more than 10 times the size required in diameter.
Hence, the need for a custom-made inkjet nozzle which can deposit femtoliter-sized droplets, measuring a whopping thousand times smaller than the ones produced by normal inkjets. These droplets utilize organic solvents in the ink which are so small, the solvent evaporates even before they manage to touch the surface. As for the “ink”, it features silver nanoparticles that are deposited in dots as small as 1µm. A one-hour heating session of up to 130°C will cause these dots to coalesce into conducting wires.
With just a single pass print, one will be able to produce silver wires that has a fair bit of resistance which can be reduced by printing over the same line a number of times. The semiconductor gates when operated at 3V managed to yield an on:off current ratio of about 106 which is touted to be some of the best figures ever generated with an organic TFT. Well, I can’t wait for circuit boards to be printed in the future, but that will still take a fair bit of time before the technique is perfected for complicated stuff like motherboards.