Enabling fine wire printing at 30 μm and less, with potential to further improve transparency and flexibility for electronic devices such as display devices and next-generation automotive window defoggers
TANAKA Kikinzoku Kogyo K.K. (Head office: Chiyoda-ku, Tokyo; Representative Director & CEO: Koichiro Tanaka), which operates the TANAKA Precious Metals manufacturing business, announced today that TANAKA has developed a Low-Temperature Sintering Nano-Silver Paste for Printed Wiring optimized for screen printing1 and current availability of samples. This product enables miniaturization and improved bending resistance of wiring, for use in screen printing, which is a mainstream printing method used in the field of printed electronics. For this reason, it is expected to be widely used for flexible devices such as smartphones and wearable devices that need bending resistance, and for improving transparency in window defoggers and other products for which demand will grow as electric vehicles become more popular.
Product Features
■ Paste suited to printing fine wires of 30 μm and less
Normally, the limit for printing wires in the screen printing process is about 50 μm in width. However, by combining suitable printers and screens with this paste, it is possible to print fine wires (30 μm and less) directly onto glass, which is a difficult medium for fine-line printing, and onto other materials such as PET film3 and green sheets. This will enable higher performance and improved productivity for electronic devices that require transparency, including window defoggers for next-generation vehicles and transparent antennas for 5G applications.
■ Bending resistance for printed wiring
Wires printed on PET film and other bendable organic substrates (100 μm printed wiring) were proven to show zero breakages over 100,000 cycles when subjected to a bending test with a bending radius of 0.5 mm. This product is therefore expected to be used for flexible devices such as smartphones and wearable devices that need both flexibility and durability.
■ Low resistance of 10 μΩcm and less
When sintered at heating temperatures of around 90°C, wires have a resistance value below 10 μΩcm, giving this product unusually low resistance even for a low-temperature sintering nanosilver paste.
■Nano-silver paste optimized for screen printing
This printing paste consists of nano and submicron silver particles suited to screen printing, which is the most common printing method used in the field of printed electronics. The paste was successfully developed to create wires with good resistance to bending and improved screen printing performance, through particle size control, solvent selection, and additives like polymer compounds, to optimize it for screen printing. The use of fine wiring in using screen printing, which is a general printing process, is also expected to deliver improved productivity.
As a result of these advantages, this product is expected to contribute greatly to a range of electronic devices that will contribute to the IoT (internet of things) society, from fine wire heating technologies that prevent glass fogging (a need that is expected to increase as electric vehicles become more popular) to healthcare-related wearable devices and 5G-oriented transparent antennas that do not compromise the view.
Samples of the product are already available with the aim of starting mass production before the end of 2022.
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