Assisted sintering of silver nanoparticle inkjet ink on paper with active coatings

Abstract

Inkjet-printed metal films are important within the emerging field of printed electronics. For large-scale manufacturing, low-cost flexible substrates and low temperature sintering is desired. Tailored coated substrates are interesting for roll-to-roll fabrication of printed electronics, since a suitable tailoring of the ink-substrate system may reduce, or remove, the need for explicit sintering. Here we utilize specially designed coated papers, containing chloride as an active sintering agent. The built-in sintering agent greatly assists low-temperature sintering of inkjet-printed AgNP films. Further, we examine the effect of variations in coating pore size and precoating type. Interestingly, we find that the sintering is substantially affected by these parameters. IntroductionThe interest in printed electronics and other printed functionalities is considerable worldwide. In contrast to traditional subtractive photolithography-and etching processes, the printing process is purely additive, which means less material waste and a reduced need for processing chemicals. This results in cost savings and environmental advantages, in particular when large area coverage is desired. Additionally, printing processes have good compatibility with flexible substrates such as plastic films and paper. Applying electronic-or other functionality on flexible, low-cost substrates, across large areas in roll-to-roll processes, enables novel applications with large potential. Among the many important applications for printed electronics are photovoltaic devices . It is capable of covering large areas with simple and cost-effective setups. Furthermore, the non-contact nature of deposition allows it to be used for delicate and pressure-sensitive surfaces. The ink formulation is relatively challenging. To be reliably jetted, properties such as viscosity, surface tension, volatility and particle size need to be well controlled. To avoid aggregation, the particles are typically stabilized using polymers that adhere to the surfaces. Depending on the specific polymers and electrical charges in the system, the stabilization may be either steric, electrostatic or a combination of both (electrosteric) 13 . Some of the most common stabilizing polymers are polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) 14 .Electrically conducting layers are important since they are included in most applications of printed electronics. Although conductive inkjet inks may be formulated from several classes of materials, including conductive polymers 15 , carbon-based materials 16,17 , and metal nanoparticles (NPs) [18][19][20] . The metal NP inks are particularly suitable when high conductivity is required, for example when printing antennas 21 and circuit board conductors 22,23 .Paper-based substrates for printed electronics are interesting for several reasons. Environmental friendliness, flexibility and low cost are the key benefits. The physical and chemical properties may be altered by chemical additives or changes in materials and processes. Therefor...

Printing Conductive Nanomaterials for Flexible and Stretchable Electronics: A Review of Materials, Processes, and Applications

“…Paper‐based substrates have recently attracted increasing research and commercial interests for PE due to their natural abundance, light weight, renewability, mechanical flexibility, and nontoxicity over their counterparts . Coffee ring effect is often undesired but does exist during inkjet printing process.…”

Inkjet Fabrication of Copper Patterns for Flexible Electronics: Using Paper with Active Precoatings

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 coalescence of Ag NPs. 35 Therefore, we used SEM imaging of the unprocessed CuO films to examine any possible aggregation of CuO NPs for each paper series. No difference in CuO layer morphology was noted with the different precoatings (Supporting Information, Figure S3).…”

“…Recently we showed that this paper design assisted low-temperature sintering of AgNP ink. 35 Here we demonstrate that the CaCO 3 precoating enhances reliability and effectiveness during IPL processing of CuO, thereby substantially improving the performance of inkjet-printed copper films.…”

Flexible hybrid circuit fully inkjet-printed: Surface mount devices assembled by silver nanoparticles-based inkjet ink

“…In order to solve this issue, the paper substrate that we selected is provided by a CaCO 3 precoating. Ohlund et al 52,53 demonstrated that AgNP ink sintering could be impaired by the coating pore size but greatly enhanced by using a porous CaCO 3 precoating. They proved that small concentrations of Cl and Ca are present on the surface of the paper with CaCO 3 precoating, and due to the presence of Cl in the AgNP ink, low temperature sintering with high conductivity values of printed pads can be facilitated by the presence of chloride.…”