Electrical characterization and modeling of simultaneous switching noise for leadframe packages

Quad flat packages with a leadframe made of copper, or alloy 42 are widely used for CMOS digital applications. To investigate the relationship between package inductance and switching noise, three types of leadframe materials, Cu, alloy 42, and Ag-plated alloy 42 were tested for frequency-dependent properties. Experiments were executed by using a CMOS noise generating chip to measure how leadframe materials influence switching noise in conjunction with output buffer characteristics. Alloy 42 showed high permeability of ferromagnetics, making it unsuitable for high-speed CMOS applications. Measured values of inductance and resistance corresponding to the frequency of the edge rate were used in modeling the leadframe packages.