ESD CHARACTERISTICS OF A GENERALIZED 2 BODY SYSTEM INCLUDING A GROUND PLANE

Capacitance coefficients were measured for a system with two conductors of variable size, positioned at different elevations with respect to a horizontal ground plane. For a constant charge on the source, body potentials and energies were calculated, and a comparison was made of the relative probability of a discharge and the severity of the discharge for the various source/sink geometries. Both a fixed-size source model and a fixed-size sink model were analyzed for cases where the sink was floating or grounded. For the case where both bodies are floating, both the relative probability of discharge and the severity of the discharge decrease if the size of the source is increased relative to the size of a fixed sink or the size of the sink is decreased relative to the size of a fixed source. For a system in which the sink is grounded, both the relative probability of a discharge and the severity of a discharge decrease if the size of the source is increased relative to the size of a fixed sink and increase if the size of the sink is decreased relative to the size of a fixed source. Positioning the bodies close to a horizontal ground plane decreases both the probability of a discharge and the severity of the discharge. Potential and energy sensitivity factors were calculated and used to show how the observed results can be interpreted using the changes in the capacitance coefficients of the system. The results provide a better understanding of the basic ESD characteristics for simulations involving the human body model and the metallic cart model.