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File design and mfg test process for high yielding and high reliability Head Disk Drives

IP.com Disclosure Number: IPCOM000015319D
Original Publication Date: 2001-Dec-09
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Abstract

One difficulty in high areal density file designs is that as track pitches are reduced, the tolerance on head magnetic widths, both read and write widths, need to scale appropriately. This represents a significant lithographic and process challenge for the head manufacturers. If the tolerance's are not scaled sufficiently, then the possibility of adjacent track squeeze may be increased, as well as the possibility of miscompares where a new data field is written sufficiently off track and did not erase the old data allowing for the possibility of both data to be read depending on the position of the read head, this case occurring with narrow read and write heads. One solution to this problem is to sort heads into separate bins and build actuators with heads on one bin type. The files for those heads would be "customized" to be optimal with its bin. For example, the simplest is to sort by write width and then select the track pitch for the file suitable with the write width, narrow writers would support smaller track pitches, and so forth. The write width screening could be either physical measurements of the write width, P2B, or magnetic measurements made on a component spin stand. A more attractive "binning" strategy would be to sort the heads so that file for each different bin would have the same areal density. This would make the file population look more homogenous across bins. The narrow track pitch file would have more cylinders and thus work at a lower BPI. This then puts less demand on those heads to have high resolution and the bin would be so tailored. Thus the binning would be best handled with HGA mag test, the screening parameters would be amplitude, resolution, read and write width. This strategy then makes use of a wider range of heads than would be otherwise possible for only one track pitch. Also by binning, the range of head widths in each bin can be chosen so as to have better margin for squeeze and miscompare than a design with one track pitch. Finally be binning heads that work better with the BPI associated with the HDD track pitch, HDD yields can be improved. 1

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  File design and mfg test process for high yielding and high reliability Head Disk Drives

   One difficulty in high areal density file designs is that as track pitches are reduced, the tolerance on head magnetic widths, both read and write widths, need to scale appropriately. This represents a significant lithographic and process challenge for the head manufacturers. If the tolerance's are not scaled sufficiently, then the possibility of adjacent track squeeze may be increased, as well as the possibility of miscompares where a new data field is written sufficiently off track and did not erase the old data allowing for the possibility of both data to be read depending on the position of the read head, this case occurring with narrow read and write heads.

One solution to this problem is to sort heads into separate bins and build actuators with heads on one bin type. The files for those heads would be "customized" to be optimal with its bin. For example, the simplest is to sort by write width and then select the track pitch for the file suitable with the write width, narrow writers would support smaller track pitches, and so forth. The write width screening could be either physical measurements of the write width, P2B, or magnetic measurements made on a component spin stand. A more attractive "binning" strategy would be to sort the heads so that file for each different bin would have the same areal density. This would make the file population look more homogenous across...