Researchers at the University of Illinois Urbana-Champaign and British flexible electronic manufacturer PragmatIC claim to have developed the first fully functional plastic processor that can realistically be made for less than a cent. Realistic as in: in a commercial manufacturing process with high yield.
The key to success, however, was not so much the manufacturing process but the design, the collaborators told IEEE Spectrum. Instead of adapting existing architectures to plastic substrate, they tailored the design to the functionality that would typically be expected from such processors. Going back to 4- and 8-bit logic, skimping on the number and complexity of instructions – anything to keep the number of gates down, which greatly boosts yields.
The 4-bit version of the 5.6 mm2 Flexicore processor has just over 2100 components on board, compared to over 56,000 in the Plasticarm, a plastic adaptation of Arm’s 32-bit Cortex M0 architecture that was also co-developed by PragmatIC. Currently, however, Plasticarm-type chips can’t match the respectable 81 percent yield obtained for the Flexicore. Both processors are made in indium gallium zinc oxide (IGZO) thin-film technology.