Printed Electronics Makers Now Seek Optimized Equipment and Process Integration


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Printed Electronics Makers Now Seek Optimized Equipment and Process Integration

Progress in materials development and bootstrapping graphic printing industry equipment means it’s now quite possible to print real electronics on unconventional subtrates, but there’s still plenty of work to be done on integrating the whole process and ramping it to cost effective commercial volumes. Kovio CEO Amir Mashkoori made a plea for better printing equipment more suited to producing electronics in volume at the recent Printed Electronics USA event. His company has developed a full set of inks for the semiconductor stack, but is applying them with standard, off-the-shelf printers, not necessarily best suited to high volume deposition of these materials. “2009 will be about setting up the ecosystem,” says Mashkoori. “I want to talk to you if you have a way to speed up printing,”

Printing companies argued that the capability for commercially viable high resolution printing of electronics was more widely available than most people realized, but integration of different materials and processes still has a long way to go. “There is a practiced and in-place way to proceed in printed electronics manufacturing,” said David Sime, director of technology transfer at Sologie. “It’s not just slopping down ink anymore.” Multiple players are now able to offer <25 um features, and dimensions half that are likely to be doable in six months, given the fast pace of development enabled by the quick turnaround of printing. Though printed RFID remains a disappointment, real printed products now include glucose sensors, smart packaging, antennas, electrochromic displays, display backplanes, and batteries. Flexo and screen printing provide higher resolution that inkjet, and can do very precise work quite routinely, though these giant high volume industrial presses aren’t well suited for development work. “Printing gets you away from the pick and place machine,” notes Sime. “We don’t compete with the silicon industry, but with the pick and place industry.”

But the printed electronics sector is currently in an awkward transition phase, Sime argued, where it’s bootstrapping on existing printing industry equipment, and has yet to put its work on separate components together into consistent and compatible materials and form factors. “It’s like we’ve invented the tire, but now have to build the motor car,” he added. Particular problems remain with interconnections, which is where products usually fail, and in testing, where complexity reaching an order of magnitude or two beyond the printed circuit board creates real issues in getting better control of yields.

One issue on which there appears to be encouraging progress is fast low temperature drying or curing of the solution-deposited materials on low temperature plastic substrates running past at high speeds. Novacentrix reported its new rapid thermal processing tool heats a wide area quickly but not deeply, by using a millisecond pulse of a large beam, high intensity lamp. In a company history that rather neatly parallels the technical progress in the industry, Novacentrix started out as a supplier of nanoparticles, then turned to dispersion technology when that became the roadblock, then moved into integrating its materials into inks, and is now working with printer companies on pulse dryers and curing tools that can be used with their equipment. VP of marketing Stan Farnsworth says the rapid, high heat treatment can improve performance significantly by better removal of the solvents, creating good contact between the metal particles without damage to the substrate. He reports 20x improvement in conductivity in 0.5um silver inkjet lines on photopaper, with resistance going from 1600 mΩ/sq to 80mΩ/sq, and getting 15 mΩ/sq from thick film screen-printed silver on PET. Farnsworth says the company will have results from an improved tool for processing silicon by SEMICON West.

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