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PCBD-Jan2014

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point of view 2013: a look back continues Fortunately, these three boneheaded visions couldn't have been more wrong; printed circuit boards are the backbone of electronic technology and have taken us to a place that none of these "prophets" could have imagined in their wildest dreams. The smartphone market is approaching a billion units a year with tablets adding another 400 million to this number. Every one of these devices has at least one printed circuit board that needs to be redesigned and replaced with each new generation launch. Keep Your Chin Up Process equipment manufacturers are growing at a solid rate, which is a positive indicator for the PCB industry as a whole. Laminate and other material suppliers are also showing slight growth. So 2013 was a bit of a wash, but in this Graphene Sees the Light by Real Time with... Graphene, a one-atom-thick sheet of carbon NEPCON South China that is extremely strong and conducts electricity well, is the thinnest material ever made. Researchers believe that it could be used as a transparent electrode in photovoltaic cells, replacing a layer of indium tin oxide (ITO) that is brittle and becoming increasingly expensive. Wee Shing Koh of the A*STAR Institute of High Performance Computing in Singapore and co-workers have compared these two materials. They found that graphene outperforms ITO when used with solar cells that absorb a broad spectrum of light. Square sheets of graphene produced by today's chemical vapor deposition technology have an electrical resistance roughly four times that of a typical 100-nanometer-thick economy that is a win and with any luck, 2014 looks to be a little better. PCBDESIGN This column appeared in the December 2013 issue of The PCB Magazine. Steve Williams is the president of Steve Williams Consulting LLC (www.stevewilliamsconsulting.com) and the former strategic sourcing manager for Plexus Corp. He is the author of Quality 101 Handbook and Survival Is Not Mandatory: 10 Things Every CEO Should Know About Lean. To read past columns, or to contact Williams, click here. layer of ITO. Although adding more layers of graphene reduces its resistance, it also blocks more light. Koh and his co-workers calculated that four layers of graphene stacked together had the best chance of matching ITO's performance. Graphene has one key advantage over ITO: it allows more than 97% of light to pass through to the solar cell beneath, regardless of its wavelength. In contrast, ITO tends to block certain wavelengths more than others. "With the refinement in the graphene manufacturing process, it would be possible for the sheet resistance of graphene to be an order of magnitude lower than the current state of the art," says Koh. This would allow just one or two sheets of graphene to beat ITO on both conductivity and transparency, making graphene transparent electrodes much more widely applicable. January 2014 • The PCB Design Magazine 19

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