Metal Leadframe Surface Cleaning Prior to Electroplating by Atmospheric Pressure Glow Discharge Plasma

Metal leadframes (Alloy 42) were cleaned using atmospheric pressure glow discharge plasma. Atmospheric pressure glow plasma was generated by a RF source of 13.56MHz with a matching network (300W power) on to the leadframes free from streamers and arc. Argon (Ar) and oxygen (O2) were used as the carrier gas and reactive gas, respectively. The addition of O2 gas to Ar decreased the contact angle of water and increased the surface cleaning rate due to the ncrease of oxygen radicals in the plasma. The chemical characteristics and morphologies of leadframe surface after the plama treatment were analyzed using X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), respectively. The contact angle of 82° before the plasma treatment was decreased to 5° in the processing condition with oxygen flow rate of 50sccm, treatment speed of 100mm/sec, and input power of 300W. These surface cleaning effect will be very useful in the replacement many steps of wet cleaning before electroplating.