JPS5888872A - Floating head slider using negative pressure - Google Patents

Abstract

PURPOSE:To improve the generating efficiency of negative pressure as well as the contact start/stop characteristics, by forming the recessed and projected grooves on the negative pressure generating surface and in the flowing direction of the air, i.e., a lubricant fluid, that is, in the direction rectangular to the traveling direction of a recording medium. CONSTITUTION:A floating head slider which uses the negative pressure contains a positive pressure generating surface having a taper surface or a level difference surface at an flow-in terminal and a negative pressure generating surface containing a taper surface or a level difference surface that has an inclination contrary to the taper surface or a level difference surface of the positive pressure generating surface. Numbers of recessed and projected grooves are formed on the negative pressure generating surface 3a in the direction rectangular to the flow of the air. Thus the slider floating gaps are formed to produce a large amount of sucking force. The processing method, the number, the height of the top, etc. of the groove are decided in consideration of the form of the negative pressure slider and other specifications.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating head slider used in a magnetic disk device, and particularly to a floating head slider that uses negative pressure, which has recently become popular.

As the capacity of Toss 2 Ida becomes larger for magnetic disk devices, the amount of levitation is rapidly becoming smaller, and at present, it has been miniaturized to a level several times the molecular mean free path of air. As is well known, the sliders that have been put to practical use so far are twin-barrel positive pressure sliders that have a Cheeverd flat-type dynamic pressure gas bearing surface that has a light load and good dynamic followability. However, since the air film rigidity of this slider company is approximately proportional to the pressing force, there is a certain limit to increasing the rigidity of the slider that uses the contact start/stop method.

This is because increasing the pressing force increases the surface pressure of the slider, which poses a problem of wear during sliding contact with the recording medium. To overcome these problems, we have recently developed a next-generation slider called the Rad Slider, which utilizes negative pressure to generate negative pressure by creating a minute recessed surface using photolithography technology within the air film lubricated surface of the slider. (hereinafter simply referred to as negative pressure slider) is being actively researched. This slider company (1) can obtain a highly rigid air film while supporting a light load due to the push-sigle action of positive pressure and negative pressure, (2) has good lifting characteristics with respect to the slider's peripheral velocity. It has advantages such as being suitable for the contact start-stop method and (3) small fluctuation in slider flying height with respect to media circumferential speed, making it the most promising slider for future large-capacity magnetic disk drives using thin-film media. .

Figures 1(&) and 1(b) are examples of shapes that have been proposed and considered so far. Note that figure (a) is a front view, figure (b) is a front view, and figure (b) is a front view.
) is a side view. In the figure, l is a positive pressure generation surface, 2
is the cross rail part, and 3 is the negative pressure generating surface. The most important shape parameter in the shape design of such a negative pressure slider is the reverse step on the negative pressure generating surface, and the depth between the steps, which is approximately several μm - 105 m1i degree from the viewpoint of air film rigidity. . Furthermore, the accuracy of the depth of the negative pressure generating surface is very strict and only a tolerance of 1μrIA 11 degrees is allowed with respect to the design center value. Therefore, the method of processing the negative pressure generating surface is a mechanical problem, and the current ion etching method using the ζ-rotation technique is being applied. In the case of such a negative pressure slider, the force W applied from the outside of the slider to the load spring, etc. is W = Wp - Wn, where Wp is the positive buoyancy force generated on the slider surface, and Wn is the suction force.
・・・・・・・・・ It is given by (1). In addition, the effective slider rigidity of the negative pressure slider has a negative rigidity due to the suction force, so Wp... (2
). Therefore, when designing the shape of the negative pressure slider,
It is necessary to generate a sufficient suction force, ie, negative pressure, to draw the recording medium toward the recording medium, and also to ensure that the negative pressure is not affected by variations in various dimensions of the slider. The larger the suction force, the more rigid the air film can be obtained under the condition of small load according to equation (1), which means that the contact start force (C8S) characteristics are good and the dynamic stability of levitation is also improved. This is because it means an excellent slider.

An object of the present invention is to provide the negative pressure slider with a slider shape that is more efficient in generating negative pressure than conventionally proposed negative pressure sliders.

The negative pressure slider of the present invention achieves the above-mentioned effect by providing unevenness 01111 on the surface of the reverse step surface, which is a negative pressure generating surface, in a direction perpendicular to the flow direction of air, which is a lubricating fluid (=running direction of the recording medium). Go with something that has achieved its purpose.

According to the negative pressure slider of the present invention, the negative pressure generating efficiency is lower than that in the case where the reverse step surface, which is the negative pressure generating surface, is an ideal flat surface because of the uneven grooves. Therefore, a highly rigid slider can be realized with less load.)
Therefore, it is possible to easily obtain a negative pressure slider having stable dynamic followability and good contact start force (C8S) characteristics.

This will be explained in detail below using the drawings.

FIGS. 2(&) and (b) show one embodiment of the present invention. Note that the figure (&) is a front view, and the figure (b) is a side view. The present invention is characterized in that many uneven grooves are provided on the negative pressure generating surface 3aKII in a direction perpendicular to the flow of air, which is a sliding fluid. With this configuration, the negative pressure generation efficiency increases at 113 m, and the
m gravitational force will be generated.

This fact can be obtained by solving the modified Reynolds equation, which governs the levitation characteristics of a floating RAD slider operating with a levitation amount in the submicron range, in a multivalued manner using a method such as the finite element method. That is, it is sufficient to form a slider levitation gap by assuming that there are many irregularities in the shape of the reverse step surface, which is a negative pressure generating surface, and calculate the positive levitation force and suction force in that case.

The calculation pan meter is the height of the uneven grooves and the number of grooves.

FIG. 3 is a diagram showing round numerical calculation results obtained by performing a simulation on the slider suction force when there are uneven grooves. The horizontal axis is the height aγ of the uneven grooves standardized by the minimum floating amount of the slider, and the vertical axis is the suction force generated when there are uneven grooves, which is based on the suction force that would occur in the case of an ideal flat surface. This is the amount of As is clear from the figure, more suction force is generated when the negative pressure generating surface has uneven grooves. This is because the concave and convex grooves have the effect of reducing the reverse step and depth of the apparent upper pressure generating surface. Furthermore, since more suction force is generated as the height of the uneven grooves increases, it can be seen that as the height of the uneven grooves increases, the negative pressure generation efficiency increases significantly. On the other hand, since the positive buoyancy force generated on the positive pressure generating surface is almost independent of the shape of the negative pressure generating surface, the value is almost the same as when the negative pressure generating surface has uneven grooves. Therefore, the uneven grooves do not affect the positive rigidity of the slider. In addition, the pressure center position is rounded, which is almost independent of the shape of the negative pressure generating surface, and although it moves slightly toward the air inlet end, there is no major change. These results show that when the position of the pressing point that operates as an actual slider is constant, the slider of this embodiment becomes a negative pressure slider with an extremely light load and high air film rigidity. It will be necessary to make a selection depending on the situation. As for the effect of the number of uneven grooves on the negative pressure generating surface, simulations show that if the grooves are approximately 10 or more, the generation of suction force is almost independent of the number of grooves, and the effect is constant. It has become clear. Therefore, in practical terms, the number of grooves can be determined by considering the slider cost, groove processing method, etc.

Although various methods can be considered for forming the uneven grooves, a chemical etching method is suitable. That is, as described above, first, the reverse step surface, which is the negative pressure generating surface, is processed by ion etching or the like. Thereafter, a photoresist mask is applied to the positive pressure generating surface, and uneven grooves are formed by chemical etching. Since this process is different from a dry etching process, it is not very difficult and does not pose a practical problem.

As explained above in detail about the present invention, the negative pressure slider of the present invention has a large number of uneven grooves on the negative pressure generating surface in the direction perpendicular to the flow direction of the lubricating fluid. It is possible to provide a slider.

Note that any modification may be made without departing from the idea of the present invention; for example, the shape of the negative pressure slider, the shape of the uneven grooves, the height of the ridges, and the number of grooves may be different in each case. It is clear that the description of the above embodiments is not intended to limit the scope of the present invention in any way.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) show a conventionally proposed negative pressure slider, and FIGS. 2(A) and (b) show an embodiment of the present invention in which uneven grooves are provided on the negative pressure generating surface. FIG. 3 shows the change in the slider suction force when there are uneven grooves and is a factor. In the figure, 1.1 &... Positive pressure generating surface, 22a...
Cross rail part, taa...Negative pressure generation surface, δγ
...Indicates the height of the crests of the uneven grooves. Pavilion 3 Diagram 1: The height of the uneven mountain -y

Claims (1)

[Claims] A tosslider for floating using negative pressure, which has a positive pressure generating surface having a tapered surface or stepped surface at the air inflow end, and a negative pressure generating surface formed by a tapered surface or stepped surface having an inclination in the opposite direction to the tapered surface or stepped surface. A floating rad slider utilizing negative pressure, characterized in that the negative pressure generating surface of the reverse taper or reverse step is provided with several uneven grooves perpendicular to the direction of flow of air, which is a lubricating fluid.