Silver price volatility may impact conductive inks and drive change
The recent furore over some US stocks has resulted in an increase in silver prices of around 10% as retail investors turned to commodities.
Silver reached a five-month high of almost $950/kg in early February and applications may suffer as a result. While silver has many uses, such as mirrors and jewellery, conductive ink is a significant application with a market estimated by IDTechEx at around US$2.3bn annually.
By far the most common use for silver ink is in the conductive fingers and busbars onto solar panels, making silver ink an essential component in the adoption of renewable energy sources. Additionally, silver ink is used across the entire range of printed electronics technologies, such as printed pressure sensors and wearable skin patches.
The most established and widely used category of conductive ink is based on natometre-scale silver flakes, with various polymeric binders added to adjust the rheology. Silver makes up at least 80% of the cost of flake-based inks, meaning that ink prices are very sensitive to price variations of the raw material.
If silver metal prices continue to rise, it could lead to changes in the composition of conductive inks. The most obvious is an acceleration in the transition from silver to copper. However, while cheaper, copper is far more reactive than silver and oxidizes relatively quickly in air to insulating copper oxide.
Recent promising solutions, which are beginning to gain commercial traction, involve incorporating additives into copper nanoparticle-based inks that are believed to act as a reducing agent during sintering.
An additional, more subtle transition induced by rising silver prices could be a greater replacement of flake-based conductive inks by nanoparticle-based and particle-free alternatives. Both of these alternatives typically have higher conductivity than flake-based inks, up to 80% of the conductivity of bulk silver in some cases.
As might be expected, these inks are more expensive per volume due to the additional manufacturing complexity. However, since raw silver makes up a small proportion of the total cost for these alternative conductive ink formulations, they could see greater uptake at the expense of flake-based inks.
