Resistance microwelding is an important microjoining process used in the fabrication of microelectronics, MEMS and medical devices. However, the process is infeasible in the situation of terminating insulated copper wire to metal sheet due to the hindrance of the insulation coating in common opposed configuration. To address this problem, a revised electrode configuration is used. The effect of main process parameters (welding current, weld time and electrode force) were investigated by detailed mechanical testing and metallurgical examinations. A bonding mechanism with several main process stages (wire cold collapse, coating melting and withdrawing, and solid-state bonding) was proposed.