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Passive Thermal FH Adjust to Compensate Temperature Driven Head Disk Spacing Changes

IP.com Disclosure Number: IPCOM000010443D
Original Publication Date: 2002-Dec-03
Included in the Prior Art Database: 2002-Dec-03
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Abstract

There is a potential problem with todays read/write heads that thermally induced protrusion can be 0.07nm/degC. This means that (keeping other parameters constant) the magnetic and mechanical spacing would change by more than 3.5nm in normal operating ranges (5-55deg C for mobile drives). Below the current 15 nm magnetic spacing, this becomes an increasingly important contribution to the overall design budget. If not addressed, this problem will eliminate further areal density increases.

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  Passive Thermal FH Adjust to Compensate Temperature Driven Head Disk Spacing Changes

This design feature passively adjusts the slider flying height as the temperature changes to compensate the head protrusion (i.e. magnetic spacing).

In particular the design makes use of different expansion coefficients for different materials. The sketches below illustrate one implementation of the thermal FH adjustment layer.

In Figure 1, the slider body with the write coil (right hand side) is shown. The blue slider body is traditionally made of a TiC/AlO ceramic matrix. In Figure 2, the same slider is shown with the thermal FH adjustment layer in place (green layer on the top side, opposite of the ABS).

Figure 1 Figure 2

By applying this layer, the slider crown will change as a function of temperature due to the thermal mismatch between the slider body and the material on top of the slider. Alternatively, the thermal mismatch layer could be placed on the etch cavity of the ABS side of the slider.

For films applied to the top surface, to obtain a FH increase with T, the thermal expansion coefficient of the new layer on top has to be smaller than the slider body. For films applied to the bottom surface, to obtain a FH increase with T, the thermal expansion coefficient of the new layer has to be larger than the slider body.

Before applying the film/layer, the slider substrate can be preferentially etched for 1 of the phases. This would provide better adhesion/grip of the film on...