Electromagnetic interference (EMI) damage to giant magnetoresistive (GMR) recording heads

It is shown that giant magnetoresistive (GMR) recording heads can be damaged by electromagnetic interference (EMI) from a remote electrostatic discharge (ESD) event. An EMI test board is described and used to quantify EMI damage thresholds for a dipole or loop antenna attached to a GMR head. A practical example of EMI damage during resistance measurement is studied. SEM failure analysis after EMI testing shows melting damage to the GMR sensor that is similar in appearance to the damage caused by direct-contact ESD damage. It is concluded that it is important to control EMI during handling operations that involve any wires connected to the GMR recording head.