BRIEF DESCRIPTION OF THE DRAWINGS
The objects, features, and advantages of the present invention are understood within the context of the Description of the Preferred Embodiment as set forth below. The Description of the Preferred Embodiment is understood within the context of the accompanying figures, wherein:
FIG. 1 is a schematic graphical representation of the vibrational response of a slider after an HDI interaction, there being no dynamical coupling between the slider, a gimbal and a loadbeam.
FIG. 2 is a schematic graphical representation of the vibrational response of a slider, similar to that of FIG. 1a, now mounted on a gimbal and a loadbeam.
FIG. 3
a-FIG. 3d are schematic illustrations of prior art gimbal designs.
FIG. 3
e-FIG. 3f are schematic graphical representations of the vibrational response of a slider mounted on prior art gimbals of the type illustrated in FIG. 3a-FIG. 3d.
FIG. 4
a-FIG. 4b are schematic views of the top and bottom sides of a gimbal that represents a first of the embodiments of the present invention.
FIG. 4
c is a schematic graphical representation of the vibrational response of a slider mounted on the gimbal of FIG. 4a-FIG. 4b.
FIG. 5
a-FIG. 5b are schematic views of the top and bottom sides of a gimbal that represents a second of the embodiments of the present invention.
FIG. 5
c is a schematic graphical representation of the vibrational response of a slider mounted on the gimbal of FIG. 5a-FIG. 5b.
FIG. 6
a is a schematic view of the top side of a gimbal that represents a third of the embodiments of the present invention.
FIG. 6
b is a schematic view of the bottom side of the gimbal of FIG. 6a.
FIG. 6
c is a schematic graphical representation of the vibrational response of a slider mounted on the gimbal of FIG. 6a.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Each preferred embodiment of the present invention is a gimbal design that produces improved/optimized dynamic response of a slider mounted thereon (and with the gimbal being a part of a suspension) as compared to the slider response when mounted on a prior art gimbal/suspension. Such improved dynamic response can be observed, for example, in the shape and frequency dependence of the vibrational modes of the gimbal mounted slider subsequent to a HDI interaction between the slider and a disk surface asperity and/or lubricant on a rotating disk. It might, in fact, be more correct to say that the design of a gimbal should be to minimize adverse effects on the dynamics of the suspension and that such a minimization can be equated to an improvement of suspension dynamics. It is precisely these effects that the embodiments of the present invention will produce. It is noted that within the context of the following description, “distal” refers to the slider end of the gimbal, “proximal” refers to the baseplate mounted end of the suspension,” “transverse” refers to the direction, in the plane of the gimbal, that is perpendicular to the lengthwise (i.e. the proximal to distal) direction of the gimbal.
Referring now to FIG. 4a, there is seen, schematically, the distal region of a top side (looking down towards the disk surface) of a gimbal designed to meet the objects of the present invention. The ramp limiter is divided into two distally extended arms (20) (i.e., cantilevered distally outward from the body of the gimbal) that are separated, are of substantially trapezoidal shape and are connected by a transverse bar (25), typically formed of stainless steel positioned approximately at the midpoint (in the longitudinal direction) along the bars. A slider mounting pad (60) extends proximally (rearward) from the limiter and its distal edge (65) is separated from the transverse bar (25) by a space (70). The solder connecting terminals (35) attaching the traces to the slider can be seen through the space (70). These terminals will be soldered to solder balls on the distal edge of the slider. Preferably, the gimbal as well as the transverse connecting bar are made of stainless steel
Referring to FIG. 4b, there is shown a bottom view (looking up from disk) of the gimbal in FIG. 4a. There can be seen a slider (100) mounted on the mounting pad (60). A layer of insulation (not shown) is formed between the slider and the pad to prevent electrical contact between the slider and the pad. Electrical traces (insulated) (30) are attached by solder ball connections (35) to the distal edge of the slider (100) and the traces are routed transversely outward, with maximal length, to contact the outriggers at (45) and then directed proximally (rearward) along a space separating the outriggers (40) from the lateral edges of the mounting pad, but transversely inward from the outriggers and substantially between the lateral edges of the mounting pad and the outriggers. The traces are supported by a pair of trace-support tabs (50), one of which extends inward from each of the outriggers. It is noted that the traces only minimally overlap the connecting bar (25) between the limiter arms and are lengthened to properly pass over the tabs (50). The traces are routed over the space between the connecting bar (70) and have minimal contact and overlap with the actual metallic structure of the gimbal. The full transverse extension, with maximal length, of the traces to contact the outrigger at (45) insures a strong and stress-free connection between the traces and the connections to the slider.
Referring to FIG. 4c, there is shown a schematic graphical representation of the vibrational response of the gimbal mounted slider of FIG. 4a and FIG. 4b, subsequent to an HDI interaction; Comparing FIG. 4c with either FIG. 3e or 3f, it can be seen that vibrational modes have been eliminated or reduced in height. It is also noted that the mode of routing of the traces from the solder ball connections (35) outward to the outriggers (40), including the minimal contact and overlap between the traces and the gimbal structure, has minimal adverse effect on either the actual solder ball bonding process or on the static PSA/RSA performance of the gimbal. In addition, there is the clear positive benefit of minimal stress on the solder connections and on the transverse bar (25) during non-operational shocks to the gimbal. The minimization of stress in the traces provides an increased margin of safety in the operation of the suspension.
Referring next to FIG. 5a and FIG. 5b, there is shown schematic representations of another embodiment of the present invention. In FIG. 5a, there is shown an overhead schematic view of the gimbal (looking down towards the disk) showing a ramp limiter formed as two distally extending (cantelevered outward from the gimbal) and separated arms (20) of substantially trapezoidal shape. A transverse bar (25) connects the two arms and is formed adjacent to the distal edge (65) of the slider mounting pad (60), but not in contact with it and, thereby, the bar is very close to the connections between the terminal ends of the traces and the solder ball terminals (35) of the slider. In particular, the space (70) between the bar (25) and the distal edge (65) of the slider pad in this embodiment is narrower than the space (70) shown in FIG. 4a and FIG. 4b.
Referring to FIG. 5b, there is shown, schematically, the gimbal of FIG. 5a as seen when looking upward from a disk surface. The slider (100) is shown mounted on the slider mounting pad (60) and electrical traces are shown routed in a similar manner to the traces in FIG. 4b and as described above so that there is maximal transverse length of the traces and minimal contact and overlap with the transverse bar. However, because of the closeness of the connecting bar to the distal surface of the slider, a minimal portion of the traces (33) passes distally over the connecting bar before being routed proximally rearward and parallel to the outriggers. Preferably, the gimbal as well as the transverse connecting bar are made of stainless steel. Like the description of FIG. 4b, the transverse routing of the traces to contact the outrigger relieves stress in the traces and creates a strong connection to the slider.
Referring to FIG. 5c, there is shown a schematic graphical representation of the vibrational response of a slider mounted on the gimbal of FIG. 5a, subsequent to a HDI interaction. The graph is quite similar to the graph of FIG. 4c and, again, indicates superior performance to gimbals of the prior art as shown in FIG. 3e-FIG. 3f. Like the gimbal of FIG'S. 4a and 4b, the gimbal embodiment of FIG. 5a also displays excellent properties during non-operational shocks. In addition, because of the length and routing of the traces, the solder ball bonding of the traces to the slider exhibits excellent strength and a margin of safety due to the lower stress in the traces. In addition, the shape of the gimbal and the positioning of the transverse bar (25) close to the solder ball connections provides better thermal protection (the bar providing a heat sink for dissipation of heat during solder ball melting) to the slider and the layers of insulation on which it is mounted during the melting of the solder balls.
Referring now to FIG. 6a, there is shown a schematic overhead view of the top side of another embodiment of the invention which differs from the first two embodiments in that there are two transverse bars (23) and (27), typically formed of stainless steel, connecting the distally extending and separated trapezoidally shaped arms (20) of the ramp limiter. One of the transverse bars (27) is very close to the distal edge (65) of the slider bonding pad, the other transverse bar (23) is distal to bar (27), leaving a space (75) between the two transverse bars and a space (73) between bar (23) and the distal edge (65) of the slider bonding pad.
Referring next to FIG. 6b, there is shown the bottom side of the gimbal of FIG. 6a. This figure also indicates clearly a feature of all the embodiments of the invention, namely the routing of the insulated traces with maximal transverse length from the slider connections (35) to the gimbal outriggers (40), so that there is minimal contact with and overlap between the traces and the structure of the gimbal. The elliptical encircled region (15) shows how the traces pass between the two transverse bars (27) and (23), overlapping with bar (27) minimally and with bar (23) not at all. This maximal transverse length of the routing together with minimal contact and overlap between the traces and the metallic structure of the gimbal (eg. the transverse bar or bars) in the region adjacent to the trace/slider connections (35) is a feature of all the embodiments and contributes to the stress-free connections between the traces and the slider and provides a resulting margin of safety during system operation.
As can be seen, the traces are extended transversely towards the outriggers (40) and then routed proximally along the space formed between the inner sides of the outriggers (40) and the lateral edges of the mounting pad (60). The traces are supported by tabs (50) extending inward from the outriggers. Preferably, the gimbal as well as the transverse connecting bars are made of stainless steel. The traces are shown here for clarity as separate conducting leads, but it is understood that these leads will be covered with insulation and there may generally be insulation extending between the leads so that they are substantially encased in an encapsulating insulating covering.
Referring to FIG. 6c, there is shown a schematic graphical display of the vibrational modes of a slider that would be mounted on the gimbal FIG. 6a subsequent to a HDI interaction. Comparing the graph with those of FIG. 3e and FIG. 3f, there can be seen the improvement produced by the gimbal as indicated by the shapes of the vibrational modes. It is further noted that the design of the gimbal provides very good dynamic strength because of the two transverse bars (23) and (27) shown in FIG. 6a. In addition, the extra length of the routing path of the traces (30) insures lowered stress, improved margin of safety and good mechanical strength of the bonding pad connections. There is also very good heat protection of the slider and insulation between the slider and the gimbal during the process of melting the solder balls to produce the final connection between the traces and the slider.
As is understood by a person skilled in the art, the preferred embodiments of the present invention are illustrative of the present invention rather than being limiting of the present invention. Revisions and modifications may be made to methods, processes, materials, structures, and dimensions through which is formed a suspension mounted gimbal having minimal negative impact on the dynamic performance of a slider mounted on the gimbal, while still providing such a gimbal, formed in accord with the present invention as defined by the appended claims.
Patent Application
20080030900
