Facilitating electroless metalization of blind holes in glass substrates by electrochemical discharge-assisted surface roughening

Abstract

This study introduces a novel approach involving the utilization of electrochemical discharges (ECD) to roughen a glass substrate to enhance the electroless metalization within blind holes. An array of 6 × 6 microholes was machined in a glass substrate using room-temperature-based Ultrasonic machining (USM) followed by electroless nickel and copper electrodeposition. Oxidation of the electroless seed layer obstructing the conductive pathway during electrodeposition and constraints to the flow of electroless solution into microholes resulted in unfilled vias. Roughening of the glass surface with ECD enabled the deposition of a thicker electroless seed layer and also infiltrated electroless solution into microholes through a network of valleys and channels generated on the top surface. A continuous electroless seed layer deposition was demonstrated in a blind via with an aspect ratio (AR) of nearly 1.5.