Patent Application
20190122694
Hard disc drive (HDD) systems typically include one or more data storage discs with concentric tracks containing information. A transducing head carried by a slider is used to read from and write to a data track on a disc, wherein each slider has an air bearing surface that is supportable by a cushion of air generated by one of the rotating discs. The slider is carried by an arm assembly that includes an actuator arm and a suspension assembly, which can include a separate gimbal structure or can integrally form a gimbal.
As the density of data desired to be stored on discs continues to increase, more precise positioning of the transducing head and other components is becoming increasingly important. In many conventional systems, head positioning is accomplished by operating the actuator arm with a large scale actuation motor, such as a voice coil motor, to position a head on a flexure at the end of the actuator arm. A high resolution head positioning mechanism, or microactuator, is advantageous to accommodate the high data density.
The precision manufacturing of components of disk drive systems includes providing an electrical connection via solder material between sliders and suspension assemblies, either or both of which may include bonding pads. In particular, a trailing surface of a magnetic recording head can have a number of bonding pads that correspond to the same number of electrical pads that are positioned on a suspension tongue, wherein the electrical pads are connected to electrical traces. The electrical connection is provided by placing solder joints between the bonding pads and the electrical pads, which thereby electrically connects the magnetic recording head to the electrical traces.
The solder material used for electrical connection of components is often supplied via solder jetting, wherein typical trailing slider surface interconnects are provided in a single plane and arranged in a single row. Such a configuration, in combination with at least some inherent trajectory error and possible solder ball expansion upon impact with a surface to which it is applied, can lead to inadequate separation between the solder interconnect and adjacent interconnects, bonding pads, or traces. This can then lead to bridged or open connections in high connection density applications. These challenges will increase as the number of slider pads provided on a slider is increased. There is therefore a desire to provide slider configurations that allow for accurate placement of the solder connections in high density applications, along with improved control of the size and shape of the solder joints.
Aspects of the invention described herein are directed to the placement of solder materials to provide for consistent connection of sliders to their associated head gimbal assemblies in hard disc drives. Such methods and configurations are particularly beneficial with the continuing desire to decrease the size of electronic components in the data storage industry.
In accordance with an aspect of the invention, a magnetic recording head is provided that comprises a trailing surface, a plurality of bond pads in a row, each of which is spaced by a gap from an adjacent bond pad along a width of the trailing surface. Each bond pad includes two side edges spaced from each other across a width of the bond pad, wherein a width of the gap between adjacent bond pads is defined by one side edge of each of two adjacent bond pads, and a top edge extending between the two side edges. The head further includes at least one solder dam comprising nonwettable, electrically conductive solder material positioned adjacent to the top edge of at least one of the bond pads.
In accordance with another aspect of the invention, a head gimbal assembly is provided that includes a suspension comprising multiple electrical pads and a magnetic recording head. The magnetic recording head comprises a trailing surface, a plurality of bond pads in a row, each of which is spaced by a gap from an adjacent bond pad along a width of the trailing surface. Each bond pad includes two side edges spaced from each other across a width of the bond pad, wherein a width of the gap between adjacent bond pads is defined by one side edge of each of two adjacent bond pads, and a top edge extending between the two side edges. The head further includes at least one solder dam comprising nonwettable, electrically conductive solder material positioned adjacent to the top edge of at least one of the bond pads. The assembly further includes at least one solder joint having a top edge adjacent to the at least one solder dam, wherein each solder joint electrically connects one of the bond pads to one of the electrical pads of the suspension.
These and various other features and advantages will be apparent from a reading of the following detailed description.
The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:
Referring now to the Figures, wherein the components are labeled with like numerals throughout the several Figures, and initially to
Head slider 10 includes a trailing edge 12 having a series of bond pads 14 in a row over a portion of the trailing edge 12. A second series of bond pads 16 is provided in a row adjacent to the bond pads 14, wherein bond pads 16 can be relatively large in comparison to the bond pads 14 of the first row. This illustrates one of any number of orientations of bond pads 14 and 16 relative to one another.
According to the illustrated embodiment, bond pads 14 are provided for electrical connection to the many transducer devices and other devices of a developed slider design, such as including contacts for read and write transducers, read and write heaters bolometers, and/or laser elements as may be provided for operation of a head slider. Certain functional elements of such a slider require positive and negative bond pads 14 for electrical operation, while others require a single bond pad for electrical operation. These bond pads 14 are conventionally electrically connected with wires or conductor elements that are typically provided to extend along the supporting head suspension assembly for controlled operation of each of the functional elements of the head slider 10.
The relatively large second set of bond pads 16 are provided for utilization during the fabrication process of the head slider 10 from a wafer or fabricated substrate, as opposed to the operative use of bonding pads 14 for slider 10 elements during operation of a disk drive. The bond pads 16 are provided to allow for temporary positive and negative electrical connection of electrical lapping guides (ELGs) during slider fabrication processes. As such, pairs of bond pads 16 can be used as ELG pads for ELG monitoring during slider processing. Multiple pairs of bond pads 16 and ELGs are preferably utilized during fabrication.
A slider 10 of the type used in the present invention generally comprises a substrate portion and a multilayer thin film laminate portion, which usually are separated from one another by an insulator layer. The multilayer thin film laminate portion comprises the operative elements that are built within the slider 10 for functionality, as noted above, such as including read and write transducers, heater elements, photonic elements, bolometers, and the like. These elements and the like as have been or are developed for operation within a slider structure are herein referred to as transducer elements. These transducer elements can be formed as thin film structures within the multilayers of the laminate portion. Each of these structures is electrically connected with one or more bond pads to be functional, such as by conductive vias or towers that are formed through the multilayers of the laminate portion, as also known. ELG devices are formed within the multilayer laminate structure and each ELG can be connected to a pair of bonding pads by conductive vias or towers within the structure of the slider 10.
Slider 10 is securely attached to the suspension tongue 30 using adhesive, solder, or the like. The suspension tongue 30 is connected at one end to a flexure 32, wherein the area where these components intersect provides for spring-like behavior which allows the slider 10 to maintain a certain fly height relative to the disks it will be accessing. The flexure 32 further includes a plurality of electrical traces 34 formed on its upper surface (i.e., the surface that faces toward the slider 10). One end of each of the electrical traces 34 is electrically connected to one of a plurality of electrical pads 36 that are mounted on the suspension tongue 30. The opposite end of the electrical traces 34 are electrically connected to a preamplifier, for example (not shown).
As shown, each of the electrical pads 36 of the flexure 32 is positioned adjacent to a corresponding bond pad 14 of the head 10. In order to electrically connect the electrical pads 36 (and their corresponding electrical traces 34) to the bond pads 14 of the slider 10, a solder joint 40 is provided for each pair of a bond pad 14 and electrical pad 36. Although only one of such solder joints 40 is illustrated in this figure, it is understood that each of the pairs of pads 14, 36 can include a solder joint 40 that provides an electrical connection between components.
In accordance with the invention, each of the bond pads 14 further includes a solder dam 18 at its top portion, the solder dam 18 having a bottom edge 20 that is positioned and sized to be a non-wettable solder dam or stop mask area that is electrically conductive to provide an area for probing. Solder dam 18 is provided to prevent the solder joint 40 from spreading or extending upwardly beyond the bottom edge 20 of the solder dam 18 toward the bond pads 16, as is illustrated in
One configuration of layers for providing a solder dam 118 of the invention on a slider 110 is schematically illustrated in
Solder dam 118 is a non-wettable material such that when solder is applied to the area between the suspension pad 136 and the bond pad 114, a solder joint 140 is formed that will be “blocked” from extending into the area of the solder dam 118, both by the material from which the dam is made and the physical obstruction of the solder dam 118 that may not be flush with the top surface of the bond pad 114. The solder dam 118 may be made of a material such as rhodium, osmium, titanium, tantalum, aluminum, nickel, diamond-like carbon, stainless steel, and alloys of one or more materials of the group.
Another configuration of layers for providing a solder dam 218 of the invention on a slider 210 is schematically illustrated in
Yet another configuration of layers for providing a solder dam 318 of the invention on a slider 310 is schematically illustrated in
The solder dams provided herein can have a wide variety of configurations, including their height, width, and thickness, in order to limit the expansion of solder to make the solder joint. For example, the solder dam can comprise a small or large portion of the top surface of the bond pad to which it is applied. Due to the coating processes used to apply the solder dam layer to the bond pad, each solder dam will generally have a width that is the same as that of the lower layers of the bond pad, however, it is contemplated that the solder dam is at least slightly wider than the bond pad to which it is adjacently positioned.
The present invention has now been described with reference to several embodiments thereof. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. The implementations described above and other implementations are within the scope of the following claims.
