The broader impact/commercial impact of this project is centered on its ability to significantly enhance the conductive ink applications in the printed electronics market. Printed electronics is dominated by high viscosity silver pastes for screen-printing applications. However, these pastes are extremely high cost, require high annealing temperatures, and do not achieve the high conductivities with its metal content. Electroninks? particle-free silver pastes open the possibility of using of a low silver weight percentage paste that can achieve high conductivities at low temperatures enabling a range of new applications in printed electronics.
This Small Business Innovative Research (SBIR) Phase I project will focus on optimizing novel silver ink formulations that have a low weight percentage of silver (10-20%) that achieve much higher conductivity (50-90% of bulk silver) than current silver pastes (5-10% of bulk silver) at temperatures that are compatible with low-cost substrates (<150ºC). Electroninks will focus on novel silver precursor chemistries that allow full gelation of otherwise low-viscosity inks for screen-printing applications.
Printable conductive inks are critical materials currently employed in nearly all consumer electronic applications. They are in the next generation of biomedical devices and consumer electronics because they can be applied on flexible and conformal plastic substrates in conventional roll-to-roll printing environments, dramatically lowering the cost and enabling new functionality in these devices. Traditionally, these ink/pastes are made up of dispersions of metallic or carbon particles including micro- to nanoscale particles, wires, flakes, etc. The particles are typically dispersed, or stabilized, in aqueous or solvent based carriers using polymer binders, surfactants, or other organic additives. This entrenched approach, which has seen very little innovation over several decades, has many disadvantages related to performance/functionality, cost and stability. Electroninks addresses these shortcomings, and the lack of innovation in these materials by completely revolutionizing the way these printed conductive materials are made. We have developed novel, metallic based reactive inks that contain no solid particles, making it a true solution, rather than a dispersion. This printable conductive ink contains no binders, with low sintering temperature (<100°C) leading to printed films with near bulk conductivity on flexible, low-temperature compatible substrates. The films are printed from solutions of low-cost metallic pre-cursers, leading to dramatic cost savings from both a materials and manufacturing standpoint. Through direct development with our customers and partners, our Phase I results have resulted in better performing and more manufacturable inks. Because of this positive development, all of these relationships will carry on into Phase II. In conclusion, we have accomplished the following milestones over the past six months that address the technical objectives for Phase I Proposal: Optimized formulation (viscosity, rheological properties governing surface wettability and printability) of our aqueous and non-aqueous conductive silver inks. These inks have been validated for high-throughput mass-production printing by large consumer electronic device manufacturer, as shown above. The formulations have been optimized for printability while maintaining conductivity and low annealing properties. Resulting films from our inks have achieved an industry-best conductivity of >30% bulk Ag conductivity with excellent adhesion – all at annealing conditions of 85°C. EI has been approached, and received strong interest from customers including chemical companies, device integrators, and final device producers. We have gained substantial customer traction in diverse markets as detailed in our Phase I report, and are currently sampling customers in the US, as well as Asia which is where the consumer/industry electronics supply chain is primarily positioned. Additional work is required to further increase the performance and scalability of our inks to meet all stringent specs and timelines in consumer electronic devices. The results reported here combined with our customer traction to date encourage us to apply for the Phase II stage of this work with the goal to advance the commercialization of our particle free conductive inks. By developing a product that completely re-designs and revolutionizes printable conductive materials, we can address current needs and enable new applications, assuring sustainable advantages and growth. The value propositions of our formulations chemistry and inks have been thoroughly described above, as have the critical needs of our customers’ "pain points" that they address. The combination of conductivity, low annealing temperature, cost, range of viscosities, non-toxic (FDA tested), and the fundamental fact that our inks are solutions and not nanoparticle/nanowire/microflake dispersions provides our customers with tremendous value and addresses several of their pain points. These statements have been validated with many of the customers and partners above, as well as market ASPs (average selling price) and, we continue to ask and do an honest reassessment of these value propositions since this industry iterates so quickly.
