Characterization of Contact Discharge Between Small-Capacitance Devices

The giant-magnetoresistive head suffers magnetic damage from electrostatic discharge (ESD) current on the order of 10 mA and thermal damage from ESD energy on the order of 0.5 nJ. The discharge between 2-pF capacitors at 10 V gave a peak current of 34 mA, and the discharge between 100-pF capacitors at 100 V reached 1.5 A. The peak current arose on the order of picofarads and was approximately maximized at the same value of both capacitors. Theoretical energy loss was estimated by the difference between the potential energies prior to and following the discharges. The energy loss was 0.05 nJ for 2-pF capacitors at 10 V and increased in excess of 0.5 nJ for greater than 20-pF capacitors. Therefore, the discharge between picofarad capacitances tends to cause the magnetic damage, and increasing the capacitance causes the thermal damage. Comparison of the potential energy loss and the current energy derived that the contact resistance varied from more than 200 to few ohms as the voltage and the energy loss increased.