Patent Application
20080117549
Embodiments of the present invention relate to sliders and disk drives. More specifically, embodiments of the present invention relate to reducing the probability of a slider contacting a surface of a disk.
Manufacturing disk drives is a very competitive business. Companies that buy disk drives are demanding disk drives that are capable of storing data at ever higher densities. A read write head is used to read data from a disk and to write data to a disk. A slider is typically used to position the read write head over the appropriate location on a disk.
The density that data can be stored on and read from a disk is directly proportional to the height that the slider flies over the disk (also commonly known as “fly height”). For example, the closer that the slider can fly over a disk the more data that can be stored and read from the disk. However, the probability that a slider will come into contact with a disk increases as the fly height decreases. Contact between the slider and the disk can result in permanent damage to the disk. Therefore, there is an increased need to reduce the probability that the slider will come into contact with the disk.
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:
The drawings referred to in this description should not be understood as being drawn to scale except if specifically noted.
Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with these embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.
As already stated, the probability that a slider will come into contact with a disk increases as the fly height decreases. This is especially the case at the corners of the trailing edge of a slider since a slider is typically positioned, as will become more evident, so that the trailing edge is closer to a disk's surface than the leading edge. Another factor that increases the likelihood that a slider will come into contact with a disk's surface is the rolling motion of a slider during load and unload processes, as will become more evident.
Therefore, according to one embodiment, air compression mechanisms (ACMs) are associated with each corner of a slider's trailing edge. The rotation of a disk under a slider causes air to move under the slider from the leading edge to the trailing edge. As the air approaches the trailing edge, the air compression mechanisms can trap a certain amount of the air and compress it. The compression of the trapped air can provide a lifting effect thus reducing the probability that the slider's corners will come into contact with the disk's surface.
The components are assembled into a base casting 113, which provides attachment and registration points for components and sub assemblies. A plurality of suspension assemblies 137 (one shown) can be attached to the actuator arms 134 (one shown) in the form of a comb. A plurality of transducer heads or sliders 155 (one shown) can be attached respectively to the suspension assemblies 137. Sliders 155 are located proximate to the disk 112's surface 135 for reading and writing data with magnetic heads 156 (one shown). The rotary voice coil motor 150 rotates actuator arms 135 about the actuator shaft 132 in order to move the suspension assemblies 150 to the desired radial position on a disk 112. The actuator shaft 132, hub 140, actuator arms 134, and voice coil motor 150 may be referred to collectively as a rotary actuator assembly.
Data is recorded onto the disk's surface 135 in a pattern of concentric rings known as data tracks 136. The disk's surface 135 is spun at high speed by means of a motor-hub assembly 130. Data tracks 136 are recorded onto spinning disk surfaces 135 by means of magnetic heads 156, which typically reside at the end of sliders 155.
Typically a slider is manufactured using etch processes. A piece of material, such as silicon, is masked and etch processes are applied to the piece of material to remove material from the parts that are not masked. The features of a slider can be created, for example, by etching the piece of material two or more times.
As a disk 112 is rotated, the leading edge 808 of a slider 800 is the first side of the slider 800 to move over a particular location of the disk 112. The trailing edge 809 is the last side of the slider 800 to move over that same location of the disk 112.
One factor that increases the probability that a slider will come into contact with a disk's surface is the load and unload process. When a disk drive is off, the disk 112 associated with the disk drive is not rotating and the slider is “parked,” for example, on a ramp that is to the side of the disk 112. When a read or write operation is initiated, the disk 112 begins to rotate. The slider exits its parked position on the ramp and is eventually positioned at a fly height above the disk 112 at which the read/write head 156 can read data from or write data to the disk 112.
The process of moving the slider off the ramp and over the disk is frequently referred to as “loading” the slider or simple as a “load process.” When an operation, such as reading or writing data, has been completed, the slider can be parked, for example, on the ramp. The process of parking the slider on the ramp is commonly referred to as “unloading” the slider or simple as an “unload process.”
Unloading and loading the slider are critical operations as there is a danger that the read/write heads may come into contact with the disk's surface 135 resulting in damage to the disk's surface 135. For example, as a conventional slider 800 is loaded or unloaded, the suction force created by a conventional slider 800's suction pocket 814 causes the conventional slider 800 to break and to roll around, thus, increasing the probability that the conventional slider 800 will come into contact with the disk's surface 135.
However as will become more evident various embodiments of the present invention provide ACMs to counteract the breaking and rolling phenomenon of a conventional slider 800. For example, the rotation of a disk under a slider causes air to move under the slider from the leading edge to the trailing edge. As the air approaches the trailing edge, the air compression mechanisms can trap a certain amount of the air and compress it. The compression of the trapped air can provide a lifting effect thus reducing the probability that the slider will come into contact with the disk's surface.
According to one embodiment, two etches can be used to create the features such as ABS pads 202, rails 204, ACMs 220, element 206, suction pocket, etc. For example, no etch is be applied to the areas where the ABS pads 202 are. One etch may be applied to the areas where the rails 204 and the ACMs 220 are. Two etches may be applied to the areas where the suction pocket is. A part of the element 206 may not be etched and the other part of the element 206 may be etched once. Therefore, according to one embodiment the ABS pads 202 would be closest to the disk, the suction pocket would be furthest from the disk, and the rails 204 and the ACMs 220 would be in between the ABS pads 202 and the suction pocket. As can be seen, according to one embodiment, an ACM 220 would be further from the disk than an ABS pad 202.
The angle 330 formed by an ACM can vary. For example, according to one embodiment, the angle 330 is 90 degrees or less. According to another embodiment, the angle 330 may vary from approximately 20 to 90 degrees. According to one embodiment, the angle 330 formed by the ACM is small enough to cause air to be compressed, thus, reducing the probability of the slider contacting a disk.
According to one embodiment, an ACM is an extension of a rail. For example, the ACM's first portion 340 may be part of a rail. However, according to another embodiment, the ACM may be separate from a rail. For example, there may be a gap between the ACM's first portion 340 and the rail.
The length 360 and the width 370 of the ACMs can vary as depicted in
The x-axis of graphs 410, 520, 510 and 520 represent time in milliseconds (ms). The y-axis of graphs 410 and 510 depict the minimum clearance in microns between the slider and the disk's surface. The y-axis of graphs 420 and 520 represent contact force in millinewtons (mN).
Referring to graph 420, the conventional slider 800 contacts the disk's surface at approximately 3.5 ms with a force of approximately 5.5 millinewtons. Graph 410 shows that the minimum clearance, due to the conventional slider 800's contact at approximately 3.5 ms, is less than 0. However, referring to graphs 510 and 520, the slider 300A according to one embodiment never contacts the disk's surface.
At step 710, the method begins.
At step 720, a first etch is performed on the slider. For example, a piece of material, such as silicon, that a slider 200 can be made out of is masked so that the areas indicated by grey, which includes the ABS pads 202 and part of the element 206, are protected. When the first etch 211 is performed, material is not removed from the areas indicated by grey but is removed from all the other areas as indicated by black and white. Therefore, according to one embodiment, a first etch 211 is performed on the areas that the rails 204 and the ACMs 220 are formed out of. According to one embodiment, the first etch 211 creates the bottom surface of the rails 204 and the ACMs 220. Thus, the bottom of the ACMs 220 and the rails 204 would be on the same level and would be further away from a disk's surface than the ABS pads 202, according to one embodiment.
At step 730, air compression mechanisms are created near each comer associated with a trailing edge of the slider. For example, the areas indicated by grey and black are protected with a mask. When the second etch 212 is performed, material is not removed from the areas indicated by grey and black but are removed from the areas indicated by white. Therefore, according to one embodiment, the suction pocket 214 would be further from the disk's surface than the ABS pads 202, the element 206, the rails 204, and the ACMs 220. According to one embodiment, the second etch 212 creates the sides of the rails 204 and the ACMs 220.
At step 740, the method ends.
As can be seen from the description of flowchart 700, a slider 200, 300A-300C according to various embodiments can be manufactured without requiring more than two etches. Further, according to various embodiments of the present invention, the ACMs 220, 320A-320C as depicted in
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments described herein were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.
