Optimized Design of Heaters for Flying Height Adjustment to Preserve Performance and Reliability

Abstract

We developed a thermal flying-height control (TFC) slider to control the flying height of magnetic recording heads. The slider basically consists of a small heater fabricated near the read/write element. This study discusses the effect of heater size and heater location on the change in the flying height at the read/write element. We also discuss the resulting temperature rise due to the additional heat applied by the heater. Specifically, we have found that small heaters generally resulted in lower heater power per unit change in the flying height and lower head temperature rise per unit change in the flying height. In terms of heater location, we have found that a heater closer to the air-bearing surface (ABS) also tends to result in a larger change in the flying height because of the larger protrusion shape. However, the head temperature rose significantly. Therefore, shorter ABS/heater distance was a trade off lower power against higher rise in head temperature. We concluded that smaller heaters and the shorter ABS/heater distance are better as long as head reliability is ensured.Index Terms-Flying height, magnetic head slider, microactuator, thermal protrusion.

Towards fly- and lubricant-contact recording

“…The proposed approach is to let the majority of slider's air-bearing surface fly whist having the tiny read/write head area contact the lubricant on disk surface only. The thermal nano-actuator technology [10][11][12][13] and the multi-shallow step technology [2,3] can be used to make such a fly-and lubricant-contact recording mechanism possible.…”

Investigation of Mechanical Clearance Change with Thermal Flying-height Control Slider at High Altitude

“…Here, Λ x and Λ y are bearing numbers, where Λ x = 6µUl x /P a h a 2 and Λ y = 6µVl x /P a h a 2 ; X and Y are non-dimensional coordinates, where X= x/l x and Y= y/ l x , where l x is slider length; P is non-dimensional pressure, p/p a , where p is pressure and p a is ambient pressure; H is non-dimensional flying height, h/h a , where h is flying height between the slider and disk, and h a is standard flying height; Q p (D, α)/Q con is the ratio of non-dimensional flow rate coefficient of Poisseuille flow based on the linearized Boltzmann equation [11] [12] [13], where Q p is flow-rate coefficient of Poisseuille flow and Q con is flow-rate coefficient of Poisseuille flow of continuous flow which has under compression; q p is mass flow rate; D is inverse Knudsen number; Kn is Knudsen number; M a = λ a /h a , where λ a is molecular mean free path at pressure p a ; α is an accommodation coefficient at the boundary surface; U and V are disk velocities; and µ is the coefficient of viscosity.…”

“…To solve this problem, the concept of individual and in-situ adjustment of head-disk clearance by means of a micro-actuator built-in into a HDD slider has been proposed [1][2][3][4][5]. Applying this concept, the authors previously developed a thermal-flying-height-control (TFC) slider that carries a micro-thermal actuator (heater) at the trailing end of the slider [9][10][11][12][13]. A schematic image of the TFC concept is shown in Fig.…”

The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2

“…In newer drive designs, the fly height is actively controlled by a signal that changes the shape of the slider. The most common method used for this control is to embed an electrical resistive heater in the slider that will cause the transducer area to protrude closer to the disk, as is shown in Figure 6 [19][20][21]. At some point the interface may need to be designed to withstand intermittent or continuous contact [22][23][24][25][26][27].…”