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Precision Finishing of Magnetic Recording Heads

IP.com Disclosure Number: IPCOM000029474D
Publication Date: 2004-Jun-30
Document File: 4 page(s) / 360K

Publishing Venue

The IP.com Prior Art Database

Abstract

Thin film magnetic recording heads are manufactured via a deposition process followed by sequential dicing and polishing steps. During the final slider dicing operation, the edges of the sliders become chipped due to the brittle nature of the AlTiC substrate and result in a rough surface on the edge of the sliders. Without refining this edge, the potential exists to generate debris during normal hard disk drive operating conditions. On approach to resolving this issue is to polish the sliders with an abrasive tape immediately after the rowbar is diced and while it is still mounted in the fixture. Several polishing devices that can accomplish this operation are presented in this paper. The polishers contain a series of pin rollers that allow a single strand of double-sided or single sided abrasive tape to be fitted between the individual sliders. With the tape fitted between the sliders, the sliders are moved against the tape and then oscillated back and forth to polish the slider edges.

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Precision Finishing of Magnetic Recording Heads

The four major electro-mechanical components of a typical hard disk drive consist of a magnetic media disk, a thin film magnetic recording head, a drive spindle and an electromagnetic voice recorder gimbal assembly. During the read/write process, all four of these components work together to transform electrical signals to magnetic patterns in the case of writing or magnetic signals to electrical signals in the case of reading. The thin film magnetic recording head (slider) flies 10-15 nanometers above the surface of the spinning magnetic disk at speeds of around 10,000 rpms. It's imperative that the surface topography of both surfaces be free of random asperities, debris or disruptions, due to this very small gap. Consequently the environment surrounding the various components, as well as the components themselves, must remain free of microscopic debris. Extreme caution is exercised during the manufacturing to prevent any particulates or debris from entering the internal working of the drives. Similarly, the surfaces of the various components are polished and cleaned to eliminate contaminants during component manufacturing and to prevent debris formation at some future date.

One area where improvements in contamination reduction can still be realized is in the area of slider manufacturing. The thin film magnetic recording head typically is manufactured via a deposition process on a 150 mm AlTiC wafer using semiconductor manufacturing techniques. Once the deposition steps have been completed, the wafer is diced into individual rowbars. The rowbars are then mounted onto polishing jigs and undergo a series of lapping and polishing operations to expose the read/write transducers on the air bearing surface (ABS), finish the backside and correct for geometry. The manufacturing process is completed by depositing diamond like carbon on the air bearing side, ion milling the ABS surface and dicing the rowbars into individual sliders. During the slider dicing operation, the edges of the sliders become chipped due to the brittle nature of the AlTiC substrate and result in a rough surface at the edge of the air bearing side. Without refining this edge, the potential exists to generate debris during normal operating conditions. Micrographs of as sawn sliders exhibit the rough edge on the air bearing side of the slider (Figure 1).

                       Figure 1. Slider edges after dicing. One approach to eliminating the rough surface on the slider edges is to polish the edges with an abrasive tape. Unfortunately due to the minute size of the sliders and the requirement to polish the sliders independent of one another, cost can be prohibitive. On approach to resolve this issue is to polish the sliders immediately after the rowbar is diced and while it is still mounted in the fixture. A conceptual drawing of a polishing device that could accomplish this operation is illustrated in Figure 2 and was communicated to magneti...