A new ESD model induced yield loss during chip-on-film package process and it´s failure mechanism

A new model of electrostatic discharge (ESD) event is found in ICs during chip-on-film (COF) package. The behavior of this new kind of ESD is different from the human-body mode (HBM), machine model (MM) and charge device model (CDM) model. We call it the charge tape model (CTM). It often damages the gate oxides of the input circuit and output circuit in IC to result in the yield loss. The mechanism of COF package induced yield loss has been identified. Two factors dominate the yield loss. One is the ESD generation on the tape surface during COF tape reeled out process. The other one is the required high temperature for the inner lead bonding, which lowers the breakdown voltage of the gate oxide. As a result, an IC might be damaged to induce the yield loss.