Identification of Unknown Nanoparticle Formation Mechanism on OSP-treated PCB for Flip-Chip Package Using Traceback Analysis

초록

In this study, unknown nanoparticles formed on OSP (Organic Solderability Preservative)-treated PCB substrates are investigated, and their origin is verified through traceback analysis. FE-SEM analysis confirms that the nanoparticles exhibit a spherical morphology with a diameter of approximately 500 nm. Elemental and structural characterization using EDS and FT-IR reveal that the nanoparticles contain nitrogen (N)-rich compounds similar to OSP. To determine the formation mechanism of these nanoparticles, a step-by-step review of the PCB manufacturing process is conducted. Traceback analysis demonstrates that PGMEA forms spherical emulsions when mixed with deionized (DI) water during PCB cleaning. PGMEA and DI water can mix in cleaning baths or recycling pipes, and residual amounts remaining on the PCB surface may combine during subsequent cleaning cycles, resulting in emulsion formation due to the polarity difference between hydrophobic PGMEA and hydrophilic DI water. These findings confirm the importance of optimizing the PCB cleaning process to prevent unknown nanoparticle formation, ensuring improved reliability in semiconductor packaging applications. Keywords : Non-wet, OSP, Traceback analysis, Emulsion, PCB †Corresponding Author: cmyoon4321@inha.ac.kr