저널

Electroplating of Ag and Au on the functional area of lead frames are required for good bonding ability in IC packaging. As the patterns of the lead frame become finer, development of new deposition technology has been required for solving problems associated with process control for uniform thickness on selected area. Sputtering was employed to investigate the adhesion between substrate Alloy42 and Ag film as a new candidate process alternative to conventional electroplating. Coating thickness of Ag film was controlled to 3.5$mu extrm{m}$ at room temperature as a reference. The deposition of film was optimized to ensure the adhesion by process parameters of substrate heating temperature at $100~300^{circ}C$, sputter etching time at -300V for 10~30min, bias voltage of -100~-500V, and existence of Cr interlayer film of $500AA$. The critical $load L_{c}$ /, defined as the minimum load at which initial damage occurs, was the highest up to 29N at bias voltage of -500V by scratch test. AFM surface image and AES depth profile were investigated to analyze the interface. The effect of bias voltage in sputtering was to improve the surface roughness and remove the oxide on Alloy42.