Cu Salt Ink Formulation for Printed Electronics using
Photonic Sintering
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Abstract
We formulate copper salt (copper
formate/acetate/oleate) precursor
inks for photonic sintering using high-intensity pulsed light (HIPL)
based on the ink’s light absorption ability. The inks can be
developed through controllable crystal field splitting states (i.e.,
the ligand weights and their coordination around the metal centers).
The inks’ light absorption properties are extremely sensitive
to the carbon chain lengths of the ligands, and the ink colors can
drastically change. From the relationship between the ratios of C/Cu
and the required sintering energies, it is possible to ascertain that
the integral absorbance coefficients are strongly correlated with
the photonic sintering behavior. These results suggest that the ink
absorbance properties are the most important factors in photosintering.
The wires formed by sintered copper formate complex ink via the HIPL
method showed good electronic conduction, achieving a low resistivity
of 5.6 × 10<sup>–5</sup> Ω cm. However, the resistivity
of the wires increased with increasing contains carbon chain length
of the inks, suggesting that large amounts of residual carbon have
negative effects on both the wire’s surface morphology and
the electrical conductivity. We find in this study that high light
absorptivity and low carbon inks would lead to a lower environmental
load in future by reducing both energy usage and carbon oxide gas
emissions