Surface Plasma and Mold Deflash Treatment of Plated and Non-Plated Cu Leadframe for Leadframe-to-Mold Adhesion Improvement

The study aims to contribute to the leadframe-to-mold interfacial adhesion through characterization of adhesion strength of two different leadframe surface ’ non-plated bare Cu and NiPdAu pre-plated and their responses to surface plasma and mold deflash treatment. Using Button Mold Shear Test, Contact Angle, Scanning Electron Microscope (SEM),Optical Surface Profiling and Scanning Acoustic Microscopy (SAM), the adhesion strength, wettability and stability to high temperature were assessed to determine susceptibility of each leadframe type to delamination and appropriate conditions to enhance adhesion with mold. The results showed that non-plated bare Cu leadframes have higher adhesion strength with mold at room or high temperature and is more responsive to plasma treatment based on average 8° contact angle. Both types encounter change in surface topography after thermal exposure but becomes rougher based on appearance of peaks, valleys and deep crevices post plasma. Non-plated leadframe exhibited significantly higher roughness than pre-plated after Ar plasma bombardment and is more stable up to TMCL 1000 cycles with no presence of delamination.