InkTec starts roll-to-roll memory printing
by Steve Bush
Monday 30 March 2009
South Korea's InkTec and Thin Film Electronics of Oslo claim to have printed memory using a high-volume roll-to-roll process.
"The project has been a huge success with the realisation of a roll-to-roll production worthy printing process capable of realising printed memory cells with a yield in the 96-97% range for the best device structure," said InkTec.
"Until now, several rolls, each with more than 100 meters of printed memory has been produced with a total of 5 printing steps."
The ink compositions for the electrodes are based on InkTec's proprietary non-particle based silver compound, whereas the memory ink is based on a proprietary ferroelectric polymer jointly developed by Thin Film and chemical giant Solvay Solexis.
"The ferroelectric can be spin-coated, printed or deposited any way," Thin Film CEO Johan Carlson told EW. "Once deposited it is baked at between 100 and 140°C to transform it into a memory material."
The memory is non-volatile, and the cell is simply an electrode-polymer-electrode sandwich.
To write to a bit, a voltage above a thickness-dependent threshold is applied which polarises the material. 0 or 1 is stored by the polarity of the voltage pulse, and the polarisation remains when the pulse is removed.
Reading is destructive - a matter of writing an arbitrary bit into the cell and monitoring the resultant current waveform to see if the polarisation swapped or not. The original polarity is then re-written.
20V is required to read and write the thick layer required to cover surface on plastic or paper, although 5V operation is possible on smoother substrates, claims Carlsson.
The polymer, whose composition is not being revealed, is non-volatile operating between -40 and +85°C, and data is retained in storage from "any negative temperature to +95°C", said Carlsson who claims testing suggests a read-write lifetime counted in billions of cycles.
Thin Film is looking to deploy its material alongside printed logic.
However, "no one has started selling printed logic today", said Carlson, so he is looking initially to add memory to otherwise passive paper products for the first products.
One possibility is something similar to Pokémon - cards that represent characters with certain abilities - but in this case those abilities can be enhanced or lost during play.
"An electronic reader would control actual game play," said Carlsson. "You would just have to store 15bits."
Once printed transistors are available, Thin Film is looking to sell its technology into bar-code replacement RFID tags.
The memories are being printed in Korea.
"We are very proud of our electronic ink," said InkTec CEO, Dr Kwang-Choon Chung. "In the future, we see Thin Film's memory technology as an important and integral part of printed radio frequency identification (RFID) products."
InkTec claims that its metal inks show improved defect properties compared to other nano-particle and paste-inks.
They are transparent silver inks printed from solution. "The inks are stable for long-term storage and are, because of the low sintering temperature, applicable to various substrates," said InkTec. |
