This invention relates generally to the field of direct access storage devices.
Direct access storage devices (DASDs) have become part of everyday life, and as such, the capability to manipulate and store larger amounts of data at greater speeds is expected. To meet these expectations, DASDs such as hard disk drives (HDDs) have undergone many changes.
The basic hard disk drive model resembles a phonograph. That is, the hard disk drive model includes a storage disk, or hard disk, that spins at a standard rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The arm carries a head assembly that has a magnetic read/write transducer, or head, for writing or reading information to or from a location on the disk. The complete head assembly, e.g., the suspension and head, is called a head gimbal assembly (HGA).
Bond pads are formed on a surface of the slider. A conductive path extends from the head to the bond pads, which in turn are connected to wires that carry information between the disk and the host computer system.
Advances in magnetic read/write heads as well as in the disk have allowed more data to be stored and quickly accessed. The ability of an HDD to access this data is largely a function of the performance of the mechanical components of the HDD. Once this data is accessed, the ability of an HDD to read and write this data is primarily a function of the electrical components of the HDD. Other advances have led to significant reductions in the size of the hard disk drive.
A problem that can occur during fabrication is referred to as “bond pad bridging.” After the bond pads are formed, subsequent cleaning and mechanical processes during fabrication may cause the pads to spread, bringing adjacent pads in contact with each other, thereby introducing a short. If the bond pads are placed closer to each—to increase the number of bond pads without increasing the size of the device, for example—the problem of bond pad bridging can become worse.
If a short is introduced, the device has to be discarded, reducing yields. A solution to the problem of bond pad bridging would therefore provide value by increasing yields.
A slider assembly used in a direct access storage device includes electrically conductive bond pads formed on and protruding from the slider body. A rigid and electrically non-conductive material surrounds and abuts the bond pads. The material and the bond pads form a planar surface. The material prevents the bond pads from migrating and shorting, so that the bond pads can be placed closer together.
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.
Reference will now be made in detail to embodiments of the present invention. While the invention will be described in conjunction with the 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 detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present invention.
In the example of
Slider assembly 155, shown in enlarged view, is in general composed of a substrate upon which various materials and devices are added; not all of these materials and devices are shown or discussed. Those material and devices generally constitute a slider body 157. The slider body 157 has surfaces that can be referred to as the serial side (on which a serial number may appear), the sidewalls, and the flex side. The slider body 157 also has a surface that can be referred to as the deposit side 170, on which a number of bond pads 160 are formed. In the example of
The magnetic head 156 is formed within or on slider body 157. Although not shown in
According to embodiments of the present invention, the bond pads 160 are surrounded by and abut an insulator 165. Furthermore, the exposed surfaces of the bond pads 160 and the insulator 165 are flush with each other, so that they form a planar surface on deposit side 170 (refer also to
In one embodiment, insulator 165 of
In addition to being non-conductive, insulator 165 is a rigid material that is harder than the material from which the bond pads 160 are made. By virtue of its hardness and rigidity, insulator 165 prevents the bond pads 160 from spreading or migrating. In effect, insulator 165 separately encloses each of the bond pads 160, so that spreading of the bond pads is inhibited during subsequent cleaning and mechanical processes during fabrication. If the bond pads do not spread, then they cannot come in contact with each other. Consequently, instances of bond pad bridging can be reduced or prevented, thereby diminishing or eliminating a potential source of shorts and increasing yields. Indeed, available data shows that, with the introduction of the present invention, instances of bond pad bridging are reduced from about 1.65 percent to about 0.14 percent.
Also, because bond pad bridging can be reduced if not prevented, the bond pads 160 can be placed closer to each other, allowing the slider assembly 155 to be reduced in size, or allowing the use of more bond pads without having to increase the size of the slider assembly. In one embodiment, the distance between bond pads is less than 4-5 microns, and distances less than that are achievable. More bond pads are advantageous, permitting additional electrical connections that can be used for reading and writing information or for connecting with other features associated with the head 156, such as fly height sensors.
Although specific steps are disclosed in flowchart 200, such steps are exemplary. That is, the present invention is well-suited to various other steps or variations of the steps recited in flowchart 200.
Also, other processes and steps associated with the fabrication of a slider assembly, HDD or DASD may be performed along with the process illustrated by
With reference to
In block 204, a non-conductive material (insulator 165) is deposited or grown between and over the bond pads 160 so that the bond pads are covered by the insulator. In one embodiment, the insulator 165 is deposited to a depth of about six (6) microns. In one embodiment, the insulator 165 is made of the same material as the substrate 302.
In block 206, a process such as, but not limited to, chemical-mechanical polishing (CMP) is employed to remove the insulator 165 until the bond pads 160 just barely begin to show, exposing enough of the bond pads 160 to permit wire bonding. As a result, the specified height of the bond pads is maintained, and the bond pads 160 and the insulator 165 form a planar surface. That is, the surface of deposit side 170 (
Continuing with reference to
In block 208, a process such as CMP can be used to remove the portion 306, so that the surfaces of the bond pad and the insulator are again flush. Because the insulator 165 is made of a material that is harder than the material used to make the bond pads, the surface of the insulator serves as a reference surface at this point in the fabrication process—the depth of the insulator 165 serves as a reference point that identifies how much of the bond pads to remove and when to stop removing the bond pad material, so that the stripe height can be properly controlled.
In summary, embodiments in accordance with the present invention pertain to HDD and DASD sliders, and methods for fabricating such devices, in which the potential for bond pad bridging is reduced or eliminated, thereby increasing yields.
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.