Evaluation of GMR Head Durability against Nanoscale Scratches Using High-Field Transfer Curves

Maeda

2012

KEM

Magnetic recording technologies are continuing to advance toward higher areal densities, driven by the availability of tunneling magnetoresistive (TMR) heads. However, high areal density heads require smaller physical dimensions, and this can render TMR heads more vulnerable to mechanical stresses generated during the lapping process. Although is important to verify the durability of TMR heads against lapping, it is very difficult to perform a crystallographic analysis of the affected layer because of the small dimensions involved. In this study, we attempted to establish an advanced TMR head verification method based on a magnetic performance analysis involving micro-Kerr hysteresis loops and the magnetic noise spectrum. We found that the magnetic performance changed when nanoscale scratches were removed from the lapped surface using ion beam etching. This indicates that the lapping process produces an affected layer which deteriorates the magnetic characteristics of the TMR head. A correlation was also found between the change in magnetic performance and the morphology of lapped surface.

Section: Resultsmentioning

confidence: 99%

Section: Table 1: Detail Of Lappingmentioning

confidence: 99%

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Characterization of TMR Head Durability against Lapping Based on Magnetic Performance

Maeda

2012

KEM

“…The substrates (AlTiC (Al2O3, TiC)) are subsequently sliced into individual bars (containing 45 heads per bar) with a diamond dicing wheel. The surfaces of magnetic heads are then finished by fixed abrasive lapping [3].…”

Section: Methodsmentioning

confidence: 99%

Advanced Diamond Charging Process Using Vibrating Charging Ring in Fixed Abrasive Lapping

Horita

Yoshikawa

et al. 2011

AMR

Self Cite

In the lapping of magnetic heads and other electronic components composed of multiple materials, differences in the processing characteristics of the composite materials produce residual steps on the surface at composite interfaces. Residual step heights have been reduced to as small as a few nanometers. We investigated using fine abrasives in fixed abrasive lapping to further reduce the residual step height. This requires highly secure, high-density embedding of abrasives on the lapping plate. To this end, we evaluated the surface morphology of the lapping plate after diamond abrasive charging and investigated the embedding mechanism of diamond abrasive charging. The results obtained will assist in determining the direction of future research and development. A prototype charging ring that uses a vibrating system was developed to increase the density of abrasives embedded on the lapping plate. This diamond charging using a vibrating system was able to increase the embedded abrasive density and improve the flatness of the charging plate.

“…To evaluate the retention of the abrasive after its embedment in the lapping plate, we performed abrasive embedding by adding diamond slurry spray onto the plate as follows [2,3]. The surface of a tin alloy plate was machined with a numerically controlled lathe (SPL15, Okamoto).…”

Section: Methodsmentioning

confidence: 99%

Mechanical Characterization of Lapping Plate Materials in Diamond Charging Process

Chiba

Yoshikawa

et al. 2010

AMR

Self Cite

In the lapping of magnetic heads and other electronic components composed of multiple materials, differences in the processing characteristics of the composite materials result in “residual steps” forming on the surface at composite interfaces. Residual step heights have been reduced to as little as a few nanometers. We investigated using fine abrasives in fixed abrasive lapping for this purpose, which requires highly secure, high-density embedding of the abrasives on the lapping plate. To this end, we modeled the abrasive embedding process and investigated the relationship between the mechanical properties of the lapping plate and the retention of the abrasive, to determine the direction of further research and development. The results of this investigation revealed a correlation between the work hardening in the plate and the resulting abrasive density and cutting edge height. The investigation also showed that it is possible to suppress the reduction in lapping rate that occurs during use by increasing the work hardening coefficient of the plate.