Quality control of printed electronics using terahertz cross-correlation spectroscopy

This study explores the application of terahertz cross-correlation spectroscopy (THz-CCS) for non-contact and non-destructive quality control in the production of printed electronics. A total of 27 inkjet-printed samples were prepared using a particle-free silver ink with varying numbers of layers and sintering durations. The samples were printed on flexible polyamide substrates and measured in transmission and reflection geometries. In the transmission geometry, THz measurements were used to extract the conductivity of the samples by applying a spectroscopic multilayer model, where the conductivity of silver was modeled using the Drude model. The reflection geometry was used to identify an example of a poorly conductive sample by analyzing the peak-to-peak amplitude of the measured THz-CCS signal. Finally, the potential for increasing acquisition speeds to achieve inline quality control at 1 kHz is outlined.