Copper flake-mod hybrid inks for printed electronics

Introduction: Printing electrical conductive interconnections is a key component for the field of printed electronics. Conducting components are usually printed, followed by a post-printing step that usually involves heating in order to sinter or decompose the printed conducting element. Currently silver is commonly used in conductive inks, since silver is stable to oxidation and has the highest conductivity among metals. However silver is a very expensive material. Therefore much effort is invested in developing a high conductivity copper based ink, as a low-cost alternative. Several approaches for copper inks have been developed, however some do not enable forming patterns with good enough conductivity for industrial applications, while others require very high sintering temperatures, which limits the range of compatible plastic substrates. There is an unmet need for an oxidation- stable copper ink which can provide good conductivity at low temperatures.

Research Goal: Develop a highly conductive copper hybrid ink

Our approach: In order to print high performance patterns we prepared a hybrid ink by combining both methods (MOD and Flakes). The idea behind this method is that the complex can be used as a glue between the copper flakes, forming conductive bridges and filling up the gaps. The copper flakes (size range was 3-6 µm) were mixed with the complex to form am ink, which was printed by screen printing, and sintered. Evaluation was performed by measuring the resistance of the patterns and evaluating the printing quality.