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Method for Identification of Magnetic Particle Contamination

IP.com Disclosure Number: IPCOM000061629D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Pesch, JA: AUTHOR

Abstract

Hard magnetic particle contamination is a problem in disk files because small magnetized particles can demagnetize a magnetic disk. Particles have been found adhering to magnetic recording heads which have been responsible for disk erasures. There is commonly constant monitoring for magnetic contamination during magnetic disk, head and file manufacture. This is a costly process involving many people, much time and expensive scanning electron microscopes. A technique has been developed for detection of hard magnetic particle contamination utilizing an optical microscope. This technique is inexpensive with respect to the equipment necessary for implementation and is efficient in the use of time required to detect magnetic particles. As shown in the figure, the technique requires: 1.

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Method for Identification of Magnetic Particle Contamination

Hard magnetic particle contamination is a problem in disk files because small magnetized particles can demagnetize a magnetic disk. Particles have been found adhering to magnetic recording heads which have been responsible for disk erasures. There is commonly constant monitoring for magnetic contamination during magnetic disk, head and file manufacture. This is a costly process involving many people, much time and expensive scanning electron microscopes. A technique has been developed for detection of hard magnetic particle contamination utilizing an optical microscope. This technique is inexpensive with respect to the equipment necessary for implementation and is efficient in the use of time required to detect magnetic particles. As shown in the figure, the technique requires: 1. An optical microscope 5 having dark field illumination and magnification to 1000X. 2. A low speed motor 2 (approximately 290 rpm) with its shaft extending vertically below the microscope stage 7. 3. A cylindrical magnet split along a diameter and magnetized parallel with its axis. On one side of the diameter the magnet has a north (N) pole on its top surface. On the other side of diameter the magnet has a south (S) pole on its top surface. This magnet is attached to the motor shaft such that the axes of the magnet and shaft coincide. 4. A dish 9 made of non-magnetic material which fits conveniently on the microscope stage. The dish 9, shown in the fi...