Material informatics for conductive ink development

Anyone who has spent time in a laboratory knows that material development can be a laborious process. By utilising an AI platform to optimise experimental parameter selection and reduce the number of iterative steps, materials informatics promises much more efficient material development pathways.

In a recent press release, particle-free conductive ink company Electroninks announced a partnership with material informatics company Citrine to develop a new conductive ink with reduced resistivity (3.2µohm cm-1) and curing temperature (80°C). This is a more desirable set of properties than existing materials and should facilitate adoption for printed electronics and especially electromagnetic (EMI) shielding. The collaboration clearly illustrates the benefits that material informatics (MI) can provide to expedite improvements in the properties of pre-existing materials with clear industrial applications.

What is particle free conductive ink?

Conductive inks are a longstanding technology that underpins printed electronics. Conventional conductive inks comprise micron-scale metal flakes suspended in a solvent with polymeric binders and are widely used in applications ranging from solar panel busbars to printed/flexible sensors.

In contrast, as the name suggests, particle-free conductive inks do not contain any metal particles. Instead, a transparent solution of solvated metal salt is chemically converted in situ to produce a metal. The chemical reaction is induced by heat, light, or plasma, resulting in a smooth conductive metal layer. This particle approach brings three main advantages: high conductivity, low viscosity, and a smooth surface.

What is materials informatics?

Material informatics describes the utilisation of data-driven methods, including machine learning, in materials R&D. It can help design new materials or select the right material for a given application, optimise material processing, and more. While this can take various forms, including literature/patent analysis and sourcing data via computational chemistry, one approach (and that used to develop particle-free inks) is to facilitate experimental design and parameter selection via supervised learning algorithms.

MI can accelerate the ‘forward’ direction of innovation (properties are realised for an input material), but the idealised solution is to enable the ‘inverse’ direction (materials are designed given desired properties). If integrated correctly, MI will become a set of enabling technologies accelerating scientists’ R&D processes while making use of their domain expertise.

Compelling advantages

Particle-free inks typically have higher conductivities than their more conventional particle-based counterparts. Since the metal is formed in situ, and the proportion of binder materials can be very low, conductivity can be as high as 80% of the bulk metal. This, of course, means that less ink can be used, with the additional benefit of there being less solvent to evaporate away during curing.

The low viscosity of particle-free conductive inks reduces the risk of nozzle clogging, making them ideally suited to aerosol and electrohydrodynamic (EHD) printing. Both of these techniques have nozzles with very small apertures and are capable of printing at lines as thin as 10 and 1um, respectively. Depositing lines this narrow enables printed electronics to compete with subtractive methods such as photolithography and thus be used for semiconductor packaging.

Additionally, the smooth surface produced by particle-free conductive inks makes them highly desirable for radio frequency (RF) applications since, as signal frequency increases, surface roughness rather than bulk conductivity increasingly dominates impedance.

Key questions answered

If you would like to learn more about the opportunities enabled by the many types of conductive inks and material informatics, IDTechEx offers comprehensive and recently updated market research reports on both fields. These draw on company interviews and conference attendance to provide market forecasts, technology analysis, player profiles, investment details, roadmaps, company lists, and more, giving a clear picture of the technological and commercial landscape.