I attended a Printable Electronics workshop in Japan a couple of weeks ago.

The 200-person crowd was made up of people from R&D organizations, material suppliers and machine manufacturers. No one there could be termed a customer; everyone was there to learn and discuss the latest printable electronics.

Promotions and presentations centered on the latest technologies in the industry that included mano inks with very fine circuit lines (down to 10 microns). Inkjet printers now offer small volume capabilities down to one sheet; gravure printers are capable of printing more than 10 sheets per second, and organic semiconductor molecules realize printable transistors. Machine manufacturers are ready to provide many kinds of RTR (roll to roll) manufacturing systems with various accessories. Researchers from universities and R&D organizations spoke about the advantages of the printable electronics, focusing on the low cost in manufacturing for large-volume production.

Most manufacturers have a common problem – they are up and running, and ready to produce flexible devices, unfortunately no one is banging on their doors to produce anything. They have been waiting for an application that requires their products and technologies, but there may not be one out there. Sure, there are applications such as membrane switches, e-papers and photovoltaic cells that require their cutting edge technological savvy, but it seems some of the newer manufacturers are not in this game. DKN Research wrote about these new technologies in past newsletters, and provided consulting for many companies. Most manufacturers asked how to attract business using these new applications. The short answer is most of their competition are considered the pioneers in the market, and it will take them a long time to cut in their teeth. The manufacturing pipeline is already established, and customers may not be willing to switch to vendors that do not have a proven track record.

There are a few shortfalls with printable electronics. The first one is the very low conductivity of conductor inks compared to metallic copper; the difference is not 30 or 50%. Generally, the conductivity of typical silver ink is two orders smaller than copper foil conductors; therefore, the printed conductors are not suitable for large current circuits and high speed circuits. Another critical issue is the migration of silver atoms. Migration is a phenomenon where silver atoms move between conductors under high humidity, causing the insulation failures between the circuits to become remarkably low in a short time.

These issues cannot be ignored when designing new circuits using this printing process. Unfortunately, there is no silver bullet that will solve these problems. This is a concern for many customers, and is the primary reason why they do not use fine circuits made from silver inks. There are a few solutions, for example, some designers request barrier layers to reduce the migration. There may be other solutions out there, but circuit manufacturers do not disclose any of their technical details.

There are advantages and disadvantages when using printable electronics instead of traditional copper and silicon circuits. Once printable electronics can provide the solution and eliminate their technical disadvantages, the segment will flourish.

Dominique K. Numakura

DKN Research Newsletter #1630, October 30th, 2016 (English Edition)(Micro Electronics & Packaging)

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Headlines of the Week

1. Fujitsu developed a new voice analyzing system. It measures the satisfaction level of the customers during the conversations.

2. Toshiba developed a new automatic car driving system with new image recognition processor. It will conduct field tests with Nagoya University.

3. Riken developed a new micron size bio-pump system introducing muscles of the earthworms.

4. Panasonic commercialized a new double-sided PET/copper laminate with 3 micron line meshes for large-size touch panel sensors.

5. Canon developed the world's first InP base immersion type grating, which covers wide range infrared wavelength for large-scale telescopes. 6. Hitachi opened a training center in Ibaraki Prefecture for maintenance of wind power stations.

7. NICT developed a new design procedure for SSPD (Superconducting Nanowire Single-Photon Detector), that can control wave length characteristics.

8. Tohoku University developed an electric power generation system that converts energy from thermal radiation of the solar power with a high efficiency (5.1%).

9. Citizen rolled out new line of LEDs, “CITILED Vivid Series, Brilliant Type and Natural Color Type,” featuring high brightness.

10. AIST developed a synthesis process of tetra-alcokisilsilane (Si(OR)4) from ashes or byproducts of biological industry for organic and inorganic silicone electronics.

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