In-Situ Surface Modification and Experimental Analysis of High-Precision Microchannel Fabrication on Silicon Dioxide (SiO2) via Rotary ECDM

The integration of Through Glass Vias (TGVs) and microfluidic systems into advanced materials such as silicon dioxide (SiO ₂ ) glass has garnered significant attention owing to their exceptional thermal, chemical, and mechanical properties in various industrial applications, particularly in biomedical, bioelectronics, lab-on-chip devices etc. Electrochemical Discharge Machining (ECDM) has emerged as a promising hybrid micromachining technique for processing non-conductive materials. However, despite its advantages, the process faces several challenges, such as inadequate flushing, restricted electrolyte replenishment, and temperature variations, which collectively impact its overall machining efficiency. As a consequence, the current research work aims to strengthen the performance and enhancement of localized thermal effects and discharge stability to improve machining characteristics by incorporating tool rotation in the ECDM process, referred to as rotary-mode ECDM process. The primary aim of this research is to systematically analyze the stimulus of key process input parameters such as rotational speed of tool electrode, gap between the electrodes (IEG), applied voltage, and concentration of electrolyte on machining performance metrics, including depth overcut, and surface roughness of the microchannels. The percentage reduction in surface roughness and depth overcut gained using rotary-mode compared to standard ECDM process was 28.5% and 42.4% respectively. The optimal input parameters were identified as 68V voltage, 20 g/L electrolyte concentration, 30 mm IEG, and 500 rpm rotational speed. Additionally, the successful fabrication of a Through Glass Vias (TGVs) with microchannel structure demonstrates the technique's potential for various industrial applications like 3D integrated circuits (3D ICs), MEMS devices, biochips, and lab-on-chip.