Development of a Pre-Plating Cleaner with High Rinsability and Wettability for TGV Glass

Glass has recently garnered attention as a material for interposers and core substrates in packaging. The glass used for these applications typically contains through holes known as through-glass vias (TGV). However, their fine structure has raised concerns about poor plating inside the vias due to inadequate cleaning or rinsing. To address this issue, an optimal pre-plating cleaner for TGV glass was developed in this study. Several surfactants were examined to determine how their structure and hydrophilic-lipophilic balance (HLB) affected their rinsability. The surfactant with excellent rinsing properties was then incorporated into the developed cleaner. TGV glass with a diameter of 60 µm and a thickness of 400 µm was used for investigations of cleanability of the developed product and effects of cleaning on electroless Cu plating inside and outside the TGVs. The results showed that the developed cleaner effectively cleaned the interior of TGVs, a task difficult to achieve using an aqueous NaOH solution. The results also confirmed that cleaning the TGVs prior to the plating process significantly reduced voids in the Cu plating film. We expect the developed pre-plating cleaner to contribute to the broader adoption of glass interposers and glass core substrates.