Fabrication of High-Conductive and Reliable Embedded Circuits in Glass Substrates via Pressure-Assisted Cu Nanoparticle Sintering

This study presents a fabrication method of high-conductive and reliable embedded circuits in glass substrates through pressure-assisted sintering of copper nanoparticle paste. First, inverted trapezoidal grooves were created on glass substrates by picosecond laser modification and hydrofluoric acid etching. Then Cu particles paste with 250 nm size and 75% solid content was filled in the grooves through a two-step filling process. Finally, the samples were hot-press sintered to form conductive circuits. Using the method, embedded circuits with linewidth of 30~100 μm were fabricated on glass substrates, with a porosity of only 7.6% and a resistivity as low as 8.53 μΩ·cm. The embedded circuit structure enabled the precise linewidth control, and also enhance the mechanical interlocking of the circuit with superior adhesion, demonstrated by <5% resistance change and no detachment after tape peel tests. Compared to conventional electroplating method for circuit fabrication on glass substrates, this method eliminates the chemical residues and improves the reliability, offering a scalable solution for circuit fabrication on advanced glass substrates for 5G/6G RF components and optical modules.