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Electrically Dissipative Alumina for Recording Head Applications Disclosure Number: IPCOM000015328D
Original Publication Date: 2002-Jan-06
Included in the Prior Art Database: 2003-Jun-20

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Electrostatic Discharge (ESD) during manufacture is a source of significant yield loss in Magnetoresistive (MR) and Giant Magnetoresistive (GMR) recording heads. In such devices, the readback sensor and leads are isolated from the shields by an insulator (or read gap), typically Aluminum Oxide (Alumina or Al 2 O 3 ). Stoichiometric Al2O3 is an excellent insulator with nearly zero leakage. By its nature, the MR or GMR head structure is capacitive with the shield and sensor/leads each behaving as electrodes. Electric charge applied to such a capacitor by an ESD event can induce sufficient voltage to breakdown the insulator which isolates the electrodes in said capacitor. Electric breakdown between the shield(s) and sensor permanently damages the device. Such ESD events can occur during head manufacture or use. Disclosed is an electrically dissipative gap material which has much higher leakage than stoichiometric Alumina. A current -voltage (IV) plot which compares the electrically dissipative alumina with conventional, stoichiometric, alumina is shown in Figure 1. This dissipative gap material, when used as the read gap in a MR or GMR recording head will minimize or eliminate damage due to ESD events during head manufacture and use. As Figure 1 demonstrates, before breakdown, the dissipative alumina leaks nearly 100 times the current of conventional Alumina. During an ESD event which sources a finite amount of charge or low level of current, such a dissipative characteristic protects the device from dielectric breakdown. 100pA 100nA