ESD events of cabled GMR sensors
ESD damage from cable discharge events (CDEs) of magnetoresistive sensors is a major problem in manufacturing of magnetic tape and hard disk drives. CDEs initiated by contact to the cable pads used to connect to external electronics represent one source. This paper addresses CDEs from other points of contact, including capacitive coupling to metal objects contacting the cable. In order for capacitively coupled ESD events to damage the sensor the capacitive coupling of the two sensor leads to the external object being discharge must be different.
ESD damage and solutions in tape head manufacturing
Magnetic tape heads use a multiplicity of highly ESD sensitive read sensors. With 36 or more sensors per head in a magnetic storage tape drive, a loss in a manufacturing environment of 1000 ppm per sensor is very costly. ESD damages caused by manufacturing processes, fixtures, material and faulty testers are investigated and reviewed. A new type of ESD failure is revealed in the study. Solutions are suggested to improve and amend the observed problems.
A study of ESD protection for helical-scan tape heads
A GMR head for a helical-scan tape system is affected by two sorts of electrostatic discharges (ESD): one is from an electrified wire to a terminal of the head and another is from a tape mike to s GMR sensor. A generally available coated wire is electrified on its suface and can induce the charge on the copper core. When the wire is touching the GMR head terminal, the discharge current can damage the sensor of GMR head. Four kind of wires were meafllred with three different lengths, Resin coated wires were electrified fiom 20V to ova 1kV. The peak cmnt dischargng ta the GMR head reached from 100mA to over 1000mA.A resin coated wire as short as 5cm damaged the GMR head. Only enameled wire can be used because of my charge and any discharge current were not observed. When an ionizer is wed for neutralizing the tribocharge on the surface of the wire, the charge remaining on the copper core depends on the effectiveness of the neutralizing process. In order to avoid ESD from a tape suface to a GMR sensor, the resisitive ferrite substrate was developed to bypass the ESD current.