Through-Glass Vias (TGVs) in glass are becoming increasingly significant in the modern microelectronics packaging industry. Glass interposers, which play a crucial role in this technology, enable high-density interconnections in a variety of devices, including smartphones, displays, automotive sensors, and Micro-Electro- Mechanical Systems (MEMS) that support diverse technologies. By enabling vertical electrical connections through glass substrates, TGVs are essential for advancing device miniaturization and improving the

performance of electronic packages. Femtosecond laser pulses can be used to drill transparent materials like glass with minimal thermal effects; however, depending on the substrate thickness, thousands of pulses may be needed to create a well-defined TGV. Consequently, there is a strong demand for methods that enhance the efficiency of drilling such structures.

In this work we present our findings when producing TGVs in glass using two different approaches. The first method is the ablation-based approach where a single pulse is split into hundreds of sub-pulses each having a temporal separation of 400 ps (GHz mode) and then fired onto the surface of a soda-lime glass sample. The second method involved focusing laser pulses in the bulk of transparent materials and producing modified areas which are etchable in aqueous solutions such as KOH (also known as selective laser etching - SLE). We compare the advantages and drawbacks of both approaches in terms of processing quality and throughput.

The results of our research demonstrate the increase in drilling efficiency of TGVs and the versatility of these

techniques for transparent materials beyond traditional applications.