In the rush to find markets for functional printing, manufacturers of printed antennas, batteries, and other innovative products may be overlooking the environmental advantage of the technology.
Printed electronics has been on the verge of commercial success for nearly a decade. The technology is capable of printing small features – on the order of 10 to 100 microns (0.4 to 4 mils) – and incorporating various materials to create circuits that include both metal lines and printed elements such as resistors. Printing conductive inks onto flexible plastic or paper sounds like a wonderfully simple way to make products as varied as antennas, cables, and batteries. In practice, adapting standard techniques such as screen, flexographic, gravure, and inkjet printing to high-volume production of electronic circuits hasn’t been as easy as proponents wished.
The potential cost advantages haven’t yet convinced entire industries to embrace printed electronics. The technology faces real limitations. Widths and spacings of printed metal lines are too large for high-end circuits and may always remain so. Microprocessors will continue to be built on rigid silicon.
But printing is suitable for applications that don’t need cutting-edge processing speed. Examples include smart RFID labels on goods, flexible displays, and even memory chips. Perhaps adding the sustainability message – save energy, save resources, save money – will push manufacturers to expand their idea of what can or should be printed.
Components that incorporate printed electronics often replace conventional printed circuit boards (PCBs), which are manufactured on rigid glass-reinforced epoxy or flexible polyimide substrates. PCB manufacturing is a wasteful process. The entire board is coated with layers of photoresist, much of which is washed away to form a pattern of lines for copper plating. Copper plating is a subtractive process that requires hazardous chemicals to etch away the unwanted material.
Printing the copper wiring in a precise pattern promises a less wasteful approach. Conductive inks, also called functional fluids, are printed in the exact pattern needed, saving material consumption and the energy required to produce those materials, not to mention avoiding caustic and toxic solvents and etchants. Printed electronics also make use of thin, flexible substrates that are usually smaller and lighter than those they are replacing.
Saving Materials and Energy
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