The business of printed electronics moves extremely quickly.
I was first exposed to printed electronics in 1987, when Nortel contracted my PCB company to work with a new plastic laminate. They had cast the high-temperature plastic in the shape needed for a low-cost phone. The cast-plastic circuit board had buttons and sockets molded right in. The back was flat for the silver multilayer circuitry. The circuit was four layers with interconnects between each layer. I used the best silver ink available and created a dielectric from a UV-cured epoxy. The layers were screen printed and then metallized with copper and gold to lower the resistance of the silver. The project was successful but did not go into production due to cutbacks.
When I returned to the industry in 2008, the state-of-the-art printed electronics was simple, single-sided silver circuits (Figure 1). I knew that a significant advance in technology would be necessary if we were to progress and replace regular PCB boards and multilayers. Articles about printed electronics were published more and more each day during my five years as director of R&D at Sierra Proto Express. Articles detailed the use of low-temperature silver inks, and companies such as Nike and Proctor & Gamble openly looked for advanced, high-tech packaging solutions from printed electronics. This revival of printed electronics made me think about printing circuits as an alternative to the polluting act of etching and plating metals.
With a little push from a few friends, I entered back into printed electronics after 21 years. The first area of concern was the lack of a good, photoimagable, dielectric material for multilayer construction. From 45 years of screen-printing experience, I knew we could not support the sub-3-mil line widths needed. After many experiments, I developed a photoimagable, dielectric trench technology to create an accurate trench filled with silver ink. With help from Dave Rund at Taiyo America’s labs, I created three dielectric materials, which I then licensed to Caledon Controls in Canada and Tapco in the USA to sell my inks. This is where the story of testing and following the progress to replace PCB circuits begins.
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