Formation of an embedded electrical circuit in glass substrate by solid-state ion exchange with application of a forward/reverse voltage

Abstract

Solid-state ion exchange with an applied voltage enables metal doping of alkali-silicate glass surfaces. When the silver is used as the doping agent, application of a reverse voltage produces a silver layer buried in the glass substrate. The silver layer consists of a network of silver nanowires that have high electrical conductivity. In this work, we experimented with forming fine electrical paths in a glass substrate using silver nano-ink, an organic solvent containing dispersed silver nanoparticles printed on the glass surface, as the silver ion source. As a result, silver precipitation line of fine width/pitch (89/16.8 μm on average) were formed by sequentially applying forward and reverse voltages. We carried out a two-dimensional numerical analysis of the ionic diffusion behavior under an electric field to calculate the minimum line interval that would prevent two adjacent lines from overlapping. In this method, the buried silver layer is, in principle, connected to the glass surface via some precipitations, and we found an arrangement for the cathodes that confines the connection paths to the designed areas.