Copper has always been the conductive metal of choice for the printed circuit board industry. However, today, silver has become the primary metal ink used in the printing of many current products, as well as the primary metal ink in all other printed electronics applications. These current products include ultra-high frequency (UHF) radio frequency identification (RFID) antennas, film keypads, battery testers, and flexible displays.
Unfortunately, it is expected that silver costs will increase exponentially in the next few years, and the demand for low-cost and high-quality metal inks will emerge.
In principle, copper has excellent conductivity and therefore can be used instead of silver in most of the above applications; however, printing metal inks must overcome numerous challenges including purity, oxidation, particle size, and dispersion quality.
As part of the strategic cooperation, Applied Nanotech (ANI) is developing metal printing inks that meet the requirements of Optomec Aerosol inkjet printing solutions. The Optomec Aerosol inkjet system is ideal for printing ANI metal inks on flexible solid substrates. Aerosol inkjet printing systems have a wide range of plate viscosities and are suitable for a wide range of applicators, dispersants, additives and copper filler applications. Optomec and ANI demonstrated how to use ANI metal inks in combination with a simple sintering system to provide superior metal traces on a variety of substrates.
These metallic inks have very good compatibility with flexible substrates and they flow smoothly for use in Optomec systems. Users can process these inks in the air without the use of exotic inert gases; the drying temperatures of these inks are less than 100 degrees Celsius and exhibit stable traces of the final metal conductivity, making the ANI/Optomec solution a sought-after complete metal ink print. The ideal solution.
Due to the ANI's ever-increasing loading range and the creation of excellent copper nanoparticle dispersion quality, copper nanoparticle inks were selected for preliminary testing. ANI achieved the above breakthrough by adopting a patented production technology that can produce enough copper nanoparticles. These copper nanoparticles have predetermined characteristics and contain a selection of ink formulation dressings and dispersants.
One of the advantages of these nanoparticulate copper inks is that they can be rapidly sintered by electromagnetic radiation, such as the use of lasers in room temperature air to continuously provide metal conduction traces and achieve lower resistivities in the micro-ohm-cm range.
These conductive metals can also be firmly attached to various flexible substrate surfaces. This addition process, involving the implementation of Aerosol inkjet printing followed by easy sintering, provides manufacturers with a fast and economical method for printing electronic circuits on a wide range of substrate surfaces. The Optomec system can be used to configure and print organic solvent-based and water-based conductive metal inks.
The Optomec system delivers 0.25 microliters per second, delivering aerosol droplets from 1 micron to 5 microns in size, and can print line widths from 10 microns to 150 microns. Using ANI copper ink, a 30 micron wide copper wire can be printed on a glass substrate.
Optomec systems and ANI inks can also be used on Kapton (polyimide) substrates and produce sintered copper wires 60 microns wide and 8 microns thick.
The ANI ink adheres firmly to the Kapton substrate. The Optomec system has a large viscosity range (between 0.7 centipoise and 2500 centipoise), making it easy to quickly print and sinter various metal inks and metal pastes to meet the needs of a wide range of future applications in the printed electronics industry.