Protective overcoating for pre-solder bumps

Abstract

To provide a protective overcoating for a pre-solder bump for suspension electrical pads in a hard disk drive.SOLUTION: A hard disk drive flexure assembly includes: an insulating base layer 502 on a metal substrate 501; a first conductive layer 503 on the base layer; a plurality of electrical pads 504 on the first conductive layer, each including a second conductive layer; a preformed bump 505 composed of a solder material disposed on each pad; and a conductive cover layer on at least a part of each pre-solder bump. The conductive cover layer, e.g., gold, prevents the solder material from each pre-solder bump from being transferred to a probe during electrical check of the flexure, prevents the solder material from oxidizing, and prevents the solder splash. These techniques are especially related to narrow, small-pitch, high-density electrical pads.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present invention may relate generally to hard disk drives and, more particularly, to an approach to protective overcoating of pre-solder bumps for suspension electrical pads. [Background technology]

[0002] A hard disk drive (HDD) is a non-volatile storage device that stores digitally encoded data on one or more circular disks that have magnetic surfaces and are housed in a protective enclosure. When an HDD is in operation, each magnetic recording disk is rotated at high speed by a spindle system. Data is read from and written to the magnetic recording disks using read / write heads (or "transducers") housed on sliders that are positioned over specific locations on the disks by an actuator. The read / write heads use magnetic fields to write data to and read data from the surfaces of the magnetic recording disks. The write head operates by generating a magnetic field by current flowing through its coils. Electrical pulses are sent to the write head in different patterns of positive and negative currents. The current in the write head's coils creates a localized magnetic field across the gap between the head and the magnetic recording disk, which in turn magnetizes a small area on the recording medium.

[0003] To write data to or read data from the recording medium, the head needs to receive instructions from the controller. Therefore, the head is electrically connected to the controller in some manner so that it can not only receive instructions to read / write data, but also send information about the read and written data back to the controller. Typically, a flexible printed circuit (FPC) mounted on the suspension is used to electrically transmit signals from the read / write head to other electronic elements in the HDD. At one end, the FPC suspension assembly and the head are typically electrically connected by solder at the head slider. Conventionally, to connect these components by solder, the solder balls between the suspension electrical pads and the slider electrical pads are heated, such as by using a laser in a solder bond jet (SBJ) procedure.

[0004] Any approach that may be described in this section is an approach that could be pursued, but not necessarily an approach that has been previously conceived or pursued, and thus, unless otherwise indicated, it should not be assumed that any approach described in this section qualifies as prior art merely by virtue of its inclusion in this section. [Brief description of the drawings]

[0005] Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which: [Figure 1] FIG. 1 is a plan view of a hard disk drive (HDD) according to one embodiment. [Figure 2A] 1 illustrates an exploded view of an HDD suspension assembly, according to one embodiment. [Figure 2B] FIG. 1 illustrates a top view of an HDD head gimbal assembly (HGA), according to one embodiment. [Figure 2C] FIG. 2C is a side view of the HGA of FIG. 2B, according to one embodiment. [Diagram 3]Figure 3A is a perspective view of a pre-soldered flexure, Figure 3B is a perspective view of a slider attached to the pre-soldered flexure in Figure 3A, and Figure 3C is a perspective view of a slider electrically connected to the pre-soldered flexure in Figure 3A, according to one embodiment. [Figure 4] 1 is a flow diagram illustrating a method for manufacturing a flexure assembly for a hard disk drive, according to one embodiment. [Figure 5A] 2A-2C illustrate the formation of a conductive cover layer over the pre-solder bumps according to a first embodiment. [Figure 5B] 11A-11D illustrate the formation of a conductive cover layer over the pre-solder bumps according to a second embodiment. [Figure 5C] 11A-11D illustrate the formation of a conductive cover layer over the pre-solder bumps according to a third embodiment. [Figure 5D] 11A-11D illustrate the formation of a conductive cover layer over the pre-solder bumps according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Generally, an approach for forming protectively covered pre-solder bumps for hard disk drive flexures and the like is described. In the following description, for purposes of interpretation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. It will be apparent, however, that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices may be shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention described herein.

[0007] Introduction term References herein to "one embodiment," "one embodiment," and the like are intended to mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the invention. However, instances of such phrases do not necessarily all refer to the same embodiment.

[0008] The term "substantially" will be understood to describe a characteristic where a structure, configuration, dimension, etc. is largely or approximately as defined, but in practice manufacturing tolerances and the like may result in the structure, configuration, dimension, etc. not always or necessarily being exactly as stated. For example, describing a structure as "substantially vertical" assigns its plain meaning to the term, such that the sidewalls are for all practical purposes vertical, but may not be at exactly 90 degrees overall.

[0009] Terms such as "optimum," "optimized," "minimum," "minimize," "maximum," "maximize," and the like may not have specific values ​​associated with them, but when such terms are used herein, the intention is that one of ordinary skill in the art would understand such terms to include affecting a value, parameter, metric, and the like in a beneficial direction consistent with the entirety of this disclosure. For example, describing some value as a "minimum" does not require that the value actually equal something's theoretical minimum (e.g., zero), but should be understood in a practical sense that the corresponding goal is to move that value in a beneficial direction toward the theoretical minimum.

[0010] context It should be appreciated that a flexible printed circuit (FPC) mounted on the suspension is typically used to electrically transmit signals from the read / write head to other electronic elements in a hard disk drive (HDD), and that the FPC suspension assembly and head are electrically connected by solder at the head slider via electrical pads on the respective components. FIG. 2A is an exploded view of an HDD suspension assembly, according to one embodiment. The suspension 200 includes a base plate 202 coupled to a load beam 204 to which an optional piezoelectric (PZT) milliactuator 205 is coupled, and a flexure 206 to which an optional piezoelectric (PZT) microactuator 207 is coupled. Shown as constituting or coupled to the flexure 206 is an integral lead 206a including a laminate structure having, for example, a base polyimide (PI) polymer layer at least partially covered by a conductive layer (e.g., copper) at least partially covered by a cover PI layer. FIG. 2B is a top view of an HDD head gimbal assembly (HGA), according to one embodiment. The exemplary HGA 210 shown here includes a portion of a flexure 206 having integral leads 206a and to which a head slider 212 is electrically coupled (e.g., soldered 213). The HGA 210 is disposed at or near the distal end of the suspension 200, opposite the proximal end of the suspension 200 on the base plate 202 side. Figure 2C is a side view of the HGA 210 of Figure 2B showing the flexure 206 coupled to a load beam 204 and coupled to a slider 212 attached to the flexure 206, according to one embodiment.

[0011] The number of slider electrical connections, and therefore the number of electrical pads on the slider and on the suspension flexures, is expected to increase over time with the implementation of new technologies such as dual thermal flying height control (TFC), two-dimensional magnetic recording (TDMR), energy-assisted magnetic recording (EAMR) (heat-assisted magnetic recording (HAMR), microwave-assisted magnetic recording (MAMR), etc.). Thus, to allow room for the additional electrical pads, the distance between adjacent pads is expected to narrow (or decrease), and accordingly, the size of the pads is expected to decrease, including narrowing the pads to prevent undesired solder bridging (e.g., electrical coupling) between adjacent pads. Thus, as the number of pads increases, it becomes more difficult to connect the pads as needed by conventional SBJ solder balls, equipment, and procedures.

[0012] As it becomes increasingly challenging to connect slider pads to flexure pads with SBJ solder balls, equipment, and procedures, a "pre-solder" process is envisioned in which a photolithographic mask(s) is used to form, pre-form, or pre-configure "pre-solder bumps" of solder material (e.g., as non-limiting examples, a metal alloy consisting of tin (Sn) or tin-silver (Sn-Ag), or a lead-free material) instead of using SBJ. "Pre-solder" generally refers to pre-forming (e.g., "pre-soldering") solder bumps on electrical pads prior to a reflow-based component bonding procedure. The implementation of pre-solder bumps is believed to potentially reduce takt time, improve product yield, and reduce fabrication inactive time, and can be used for products with larger pad density (e.g., 14-pad flexure-slider assemblies), while SBJ appears to be limited in that regard.

[0013] Approaches to forming pre-solder bumps for suspension flexure electrical pads are described in U.S. Patent Application No. 17 / 702,691, entitled "Pre-Solder Formation and Guide for Hard Disk Drive Suspension Pads," and U.S. Patent Application No. 17 / 707,368, entitled "Pre-Solder Sidewalls for Hard Disk Drive Suspension Pads," the entire contents of both of which are incorporated by reference for all purposes as if fully set forth herein. For the purposes of this pre-soldering, at least two types of pre-soldering processes using photoresist are contemplated: "solder plating" and "solder paste printing and reflow." Generally, in a metal plating process, a material is deposited on a workpiece in some manner (e.g., spraying, electroplating, electroless plating, etc.). Generally, with a solder paste printing process, a solder material is spread on a workpiece with a squeegee through a mask in some manner (e.g., stencil, photoresist, etc.), and then reflowed by heating to a desired shape.

[0014] FIG. 3A is a perspective view of a pre-soldered flexure, FIG. 3B is a perspective view of a slider attached to the pre-soldered flexure of FIG. 3A, and FIG. 3C is a perspective view of a slider electrically connected to the pre-soldered flexure of FIG. 3A, all according to one embodiment. In the "pre-soldered" stage of FIG. 3A, a simplified form of a flexure (labeled flexure 306), such as flexure 206 (FIGS. 2A-2C), is shown. Flexure 306 includes a flexure head pad 306a having a number of pre-solder bumps 307 formed or "pre-soldered" thereon. In this context, each pre-solder bump 307 of solder material is formed on or above a corresponding pad (not shown) of flexure 306, so that each pre-solder bump 307 can be heated to reflow and then electrically bonded to a corresponding slider pad. Next, in the "Slider Attach" stage of FIG. 3B, the head slider 312 is shown mechanically attached to the head pads 306a of the flexure 306 prior to connection of the electrical pads (or "connection pads", "bond pads", or simply "pads"), where the pre-solder bumps 307 are aligned with corresponding pads on the slider 312 for final electrical connection. Finally, in the "Pad Connection" stage of FIG. 3C, the head slider 312 is shown in the process of being electrically bonded or connected to the flexure 306 by a laser reflow procedure, whereby solder fillets 307a are formed by reflowing the pre-solder bumps 307 (FIGS. 3A-3B) of the flexure 306 by a heat source (e.g., laser irradiation), electrically interconnecting the electrical pads of the slider 312 with the corresponding electrical pads of the flexure 306.

[0015] However, it has been found that solder material from the pre-solder bumps can undesirably transfer to a probe (e.g., a test tool) during electrical testing of the flexure. Oxidation of this transferred solder can then degrade probe performance, such as due to high contact resistance. Additionally, oxidation of the pre-solder surface can occur, which can adversely affect the bondability and wettability of the solder bumps. Although fluxes can be commonly used to prevent solder bump oxidation, due to chemical issues, fluxes are not considered suitable for flexure / HGA processes. Yet another concern with pre-solder bumps is the potential for "solder splash" during reflow. In solder splash, as pre-solder bumps are rapidly heated by laser reflow (especially considering the relatively rough solder surface that absorbs the laser more locally), air in voids within the solder bumps can rapidly expand, resulting in a splash of molten solder. In view of the aforementioned challenges, improvements to pre-solder bumps may be desirable.

[0016] Conductive Protective Overcoat for Pre-Solder Bumps According to one embodiment, at least a portion of the pre-solder bump (e.g., the top surface likely to be contacted by a test probe) is overcoated with a protective layer of material that blocks or inhibits transfer of solder material to the electrical test probe. According to a related embodiment, conductive gold (Au) is utilized as the protective overcoat material for the pre-solder bump. According to each embodiment, a number of fabrication procedures may be performed to fabricate the overcoated pre-solder bump, as described in more detail elsewhere herein.

[0017] Fig. 4 is a flow diagram illustrating a method of manufacturing a flexure assembly for a hard disk drive according to one embodiment. Figs. 5A-5D each illustrate the formation of a conductive cover layer over the pre-solder bumps according to the first to fourth embodiments, respectively, and are referenced herein in conjunction with the method of Fig. 4.

[0018] In block 402, an insulating base layer is formed on at least a portion of a metal substrate. For example, a base layer 502 (FIGS. 5A-5D), such as a polyimide polymer layer, is formed on a metal substrate 501 (FIGS. 5A-5D), such as a stainless steel (SST) layer, according to known manufacturing process techniques.

[0019] In block 404, a first conductive layer is formed on at least a portion of the base layer. A first conductive layer 503 (FIGS. 5A-5D), such as a copper printed circuit layer, is formed on the base layer 502 according to known manufacturing process techniques.

[0020] In block 406, a plurality of electrical pads each including a second conductive layer is formed on the first conductive layer. For example, a plurality of electrical pads 504 (FIGS. 5A-5D) each including a second conductive layer such as a nickel layer are formed on the first conductive layer 503 according to a known manufacturing process technique. As shown in FIGS. 5A-5D, according to an embodiment, a head slider 512 (see also head slider 212 in FIG. 2B) constituting a head gimbal assembly (HGA) (see, for example, HGA 210 in FIG. 2B) includes a plurality of electrical pads 513 located at a trailing edge (TE) opposite to a leading edge (LE) of the slider 512, to which the plurality of electrical pads 504 of the flexures 500A (FIG. 5A), 500B (FIG. 5B), 500C (FIG. 5C), and 500D (FIG. 5D) are electrically connected.

[0021] At block 408, a preformed solder bump ("pre-solder bump") made of solder material is formed that is pre-disposed on and in contact with at least a portion of each of the electrical pads. For example, pre-solder bumps 505 (FIGS. 5A-5D) made of solder material are formed on and in contact with at least a portion of each of the electrical pads 504 of the flexures 500A-500D according to known manufacturing process techniques. As a non-limiting example, each pre-solder bump 505 may be formed using solder plating or solder paste printing and reflow techniques. As described, each pre-solder bump 505 may be formed using solder plating or solder paste printing and reflow techniques, which may use some form of masking, such as photoresist (or simply "resist"), to properly position the solder material of the pre-solder bump in the desired location, i.e., for solder patterning.

[0022] At block 410, a conductive cover layer is formed over at least a portion of each pre-formed bump of solder material. For example, conductive cover layer 506 (FIGS. 5A-5D) is formed over at least a portion of each pre-solder bump 505 of solder material. Considering the conductive cover layer 506, the solder material from the pre-solder bump 505 is inhibited from transferring to the probe during electrical check / test of the flexures 500A-500D, the solder material is inhibited from oxidizing, and solder splash is inhibited. According to one embodiment, the conductive cover layer 506 includes gold (Au). In this case, even if a portion of the conductive cover layer 506 transfers to the probe, the probe performance is not expected to be degraded due to the high electrical conductivity of the gold material. Furthermore, gold has a higher thermal conductivity than solder, and gold exhibits lower optical absorption than solder at the wavelength(s) used for laser reflow. According to a related embodiment, the conductive cover layer 506 is applied as an overcoat by a PVD (physical vapor deposition) process such as thermal evaporation, sputtering, etc. Further, according to one embodiment, a cover layer 507, such as a polyimide polymer layer, is formed over the portion of the first conductive layer 503 not covered by the electrical pads 504. In response to a laser reflow process (e.g., see FIG. 3C) after slider attachment (e.g., see FIG. 3B), each pre-solder bump 505 is expected to form a solder fillet 505a that electrically connects the flexures 500A-500D to the slider 512, whereby the material of the conductive cover layer 506 (e.g., gold) forms an intermetallic (e.g., Sn-Au) layer by diffusing into the solder material of the corresponding pre-solder bump 505 in forming the solder fillet 505a.

[0023] 5A, according to one embodiment, the illustrated fabrication process includes nickel plating on a first resist mask 520 on a first conductive layer 503 to form a second conductive layer of a plurality of electrical pads 504 (e.g., at block 406), replacing the first mask with a second resist mask 521 on the second conductive layer (removing one mask and applying another mask) and solder plating thereon to form pre-solder bumps 505 on each of the plurality of electrical pads 504 (e.g., at block 408), and replacing the second mask with a third resist mask 522 and gold plating or deposition thereon to form a conductive cover layer 506 on each pre-solder bump 505 (e.g., at block 410), where the first resist mask 520 and the third resist mask 522 may have the same pattern. As shown in FIG. 5A, according to this embodiment, each conductive cover layer 506 is effectively disposed over and in contact with (e.g., covering) the entirety of each corresponding pre-solder bump 505, and each conductive cover layer 506 is disposed over and in contact with at least a portion of the second conductive layer of each electrical pad 504 that is not covered by the pre-solder bump 505.

[0024] 5B, according to an embodiment, a third conductive layer 508 (e.g., gold) is disposed between the second conductive layer of the electrical pad 504 and the pre-solder bump 505. This third conductive layer 508 provides oxidation protection for the first conductive layer 503 (e.g., copper) and stable plating for the pre-solder bump 505, since the seed third conductive layer 508 does not oxidize. In addition, since gold has better solder wettability than nickel, the molten solder material of the pre-solder bump 505 flows more easily onto the third conductive layer 508 (e.g., gold) to the slider electrical pad 513 during reflow. Again, one advantage of using a nickel layer for the electrical pad 504 is that this nickel layer acts as a barrier against the diffusion of the third conductive layer 508, which is gold, into the first conductive layer 503, which is copper. Thus, the illustrated fabrication process includes nickel plating on a first resist mask 530 on the first conductive layer 503 to form a second conductive layer of the plurality of electrical pads 504 (e.g., at block 406), gold plating on the first resist mask 530 to form a third conductive layer 508, replacing the first mask with a second resist mask 531 on the third conductive layer and solder plating thereon to form pre-solder bumps 505 on each of the plurality of electrical pads 504 (e.g., at block 408) and on the third conductive layer 508, and gold plating or deposition thereon to form a conductive cover layer 506 on each pre-solder bump 505 (e.g., at block 410). As shown in FIG. 5B, according to this embodiment, each pre-solder bump 505 is disposed on a third conductive (e.g., gold) layer 508, and each conductive cover layer 506 is effectively disposed on and in contact with only a portion (e.g., a top surface or a portion) of each of the corresponding pre-solder bumps 505. Here, only one exchange of the resist mask is required. Furthermore, since the area of ​​the side surface is much smaller than the area of ​​the top surface, the possibility of oxidation occurring on the side surface of each solder bump 505 is believed to be less significant than in the absence of the conductive cover layer 506.

[0025] Referring to FIG. 5C, according to an embodiment, a third conductive layer 508 (eg, gold) is disposed between the second conductive layer of the electrical pad 504 and the pre-solder bump 505. Thus, the illustrated fabrication process includes nickel plating on a first resist mask 540 on the first conductive layer 503 to form a second conductive layer of the plurality of electrical pads 504 (e.g., at block 406), gold plating on the first resist mask 540 to form a third conductive layer 508 on the second conductive layer of the plurality of electrical pads 504, replacing the first mask with a second resist mask 541 and solder plating thereon to form pre-solder bumps 505 on each of the plurality of electrical pads 504 (e.g., at block 408), and replacing the second mask with a third resist mask 542 and gold plating or deposition thereon to form a conductive cover layer 506 on each pre-solder bump 505 (e.g., at block 410), where the first resist mask 540 and the third resist mask 542 may have the same pattern. As shown in FIG. 5C, according to this embodiment, each conductive cover layer 506 is effectively disposed entirely over and in contact with (eg, covering) each corresponding pre-solder bump 505.

[0026] 5D, according to one embodiment, the illustrated fabrication process includes nickel plating on a first resist mask 550 on a first conductive layer 503 to form a second conductive layer of a plurality of electrical pads 504 (e.g., at block 406), replacing the first mask with a second resist mask 551 on the second conductive layer and solder plating thereon to form pre-solder bumps 505 on each of the plurality of electrical pads 504 (e.g., at block 408), and replacing the second mask with a third resist mask 552 on the second conductive layer and gold plating or deposition thereon to form a conductive cover layer 506 on each pre-solder bump 505 (e.g., at block 410). 5D, according to this embodiment, each conductive cover layer 506 is effectively disposed over and in contact with (e.g., covering) the entirety of each corresponding pre-solder bump 505, and each conductive cover layer 506 is disposed over and in contact with only a portion of the second conductive layer of each of the electrical pads 504 that is not covered by the pre-solder bump 505. Here, the pre-solder bumps 505 are disposed over the second conductive layer (e.g., nickel) such that the entirety of the pre-solder bumps 505 is covered by the conductive cover layer 506, but a portion of the second conductive layer is exposed on the root side (farthest from the slider 512), so that during reflow, the solder material of the pre-solder bumps 505 is more likely to flow toward the slider 512 than toward the cover layer 507 due to the relatively low wettability of the exposed nickel material. Thus, the solder material is efficiently used for pad connection.

[0027] Physical Description of an Exemplary Operational Context Embodiments may be used in the context of a digital data storage device (DSD), such as a hard disk drive (HDD). Thus, according to one embodiment, to help explain how a conventional HDD typically operates, a plan view illustrating a conventional HDD 100 is shown in FIG.

[0028] FIG. 1 shows a functional arrangement of components of a HDD 100 that includes a slider 110b that includes a magnetic read / write head 110a. The slider 110b and the head 110a may be collectively referred to as a head slider. The HDD 100 includes at least one head gimbal assembly (HGA) 110 that includes a head slider, a lead suspension 110c that is typically attached to the head slider via a flexure, and a load beam 110d that is attached to the lead suspension 110c. The HDD 100 also includes at least one recording medium 120 that is rotatably mounted on a spindle 124, and a drive motor (not shown) that is attached to the spindle 124 to rotate the medium 120. The read / write head 110a, which may also be referred to as a transducer, includes a write element for writing information stored on the medium 120 of the HDD 100, and a read element for reading information stored on the medium 120 of the HDD 100. The medium 120 or multiple disk media may be secured to the spindle 124 by a disk clamp 128 .

[0029] The HDD 100 further comprises an arm 132 attached to the HGA 110, a carriage 134, and a voice coil motor (VCM) including an armature 136 including a voice coil 140 attached to the carriage 134, and a stator 144 including a voice coil magnet (not shown). The VCM armature 136 is attached to the carriage 134 and configured to move the arm 132 and HGA 110 to access a portion of the media 120, all of which are collectively mounted on a pivot shaft 148 having an intervening pivot bearing assembly 152. In an HDD having multiple disks, the carriage 134 may be referred to as an "E-block" or comb, as it is arranged to carry an interlocking array of arms giving the appearance of a comb.

[0030] An assembly including a head gimbal assembly (e.g., HGA 110) including a flexure to which a head slider is coupled, an actuator arm (e.g., arm 132) and / or a load beam to which the flexure is coupled, and an actuator (e.g., VCM) to which the actuator arm is coupled may be collectively referred to as a head stack assembly (HSA). However, an HSA may include more or less components than those described. For example, an HSA may refer to an assembly that further includes electrical interconnection components. In general, an HSA is an assembly configured to move a head slider to access portions of a medium 120 for read and write operations.

[0031] With further reference to FIG. 1 , electrical signals including write signals to and read signals from head 110a (e.g., current to the voice coil 140 of the VCM) are carried by a flexible cable assembly (FCA) 156 (or “flex cable”, or “flexible printed circuit” (FPC)). The interconnect between flex cable 156 and head 110a may include an arm electronics (AE) module 160, which may have an on-board preamplifier for the read signal, as well as other read channel and write channel electronic components. The AE module 160 may be mounted to the carriage 134, as shown. The flex cable 156 may be coupled to an electrical connector block 164, which in some configurations provides electrical communication via an electrical feedthrough provided by an HDD housing 168. The HDD housing 168 (or “enclosure base” or “base plate” or simply “base”), in combination with the HDD cover, provides a semi-enclosed (or in some configurations sealed) protective enclosure for the information storage components of the HDD 100.

[0032] Other electronic components, including a disk controller and servo electronics including a digital signal processor (DSP), provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signals provided to the drive motor cause it to rotate, which imparts a torque to the spindle 124. This torque is then transmitted to the medium 120 affixed to the spindle 124. As a result, the medium 120 rotates in a direction 172. The rotating medium 120 creates a cushion of air that acts as an air bearing on which the air bearing surface (ABS) of the slider 110b rests so that the slider 110b flies over the surface of the medium 120 without contacting the thin magnetic recording layer on which the information is recorded. Similarly, in HDDs where a lighter-than-air gas such as helium is utilized as a non-limiting example, the rotating medium 120 creates a cushion of gas that acts as a gas or fluid bearing on which the slider 110b rests.

[0033] An electrical signal provided to the voice coil 140 of the VCM allows the head 110a of the HGA 110 to access tracks 176 on which information is recorded. Thus, the armature 136 of the VCM swings through an arc 180, which allows the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 in a number of radially nested tracks arranged in sectors on the medium 120, such as sectors 184. Correspondingly, each track is made up of a number of sectorized track portions (or "track sectors"), such as sectorized track portion 188. Each sectorized track portion 188 may include recorded information and a header that includes error correction code information and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information identifying the track 176. In accessing track 176, a read element of head 110a of HGA 110 reads a servo burst signal pattern that provides a position error signal (PES) to servo electronics that control the electrical signal provided to the voice coil 140 of the VCM, thereby enabling head 110a to follow track 176. Having found track 176 and identified a particular sectored track portion 188, head 110a reads information from or writes information to track 176 in response to instructions received by a disk controller from an external agent, for example a microprocessor in a computer system.

[0034] The electronic architecture of an HDD includes numerous electronic components for performing respective functions for the operation of the HDD, such as a hard disk controller ("HDC"), an interface controller, an arm electronics module, a data channel, motor drivers, a servo processor, buffer memory, etc. Two or more of such components may be combined on a single integrated circuit board referred to as a "system on a chip" ("SOC"). Some, but not all, of such electronic components are typically located on a printed circuit board that is coupled to the bottom side of the HDD, such as the HDD housing 168.

[0035] References to hard disk drives herein, such as HDD 100 shown and described with reference to FIG. 1, may encompass information storage devices sometimes referred to as "hybrid drives." A hybrid drive generally refers to a storage device that has the functionality of both a conventional HDD (see, e.g., HDD 100) and a solid-state storage device (SSD) using electrically erasable and programmable non-volatile memory, such as flash or other solid-state (e.g., integrated circuit) memory. Because the operation, management, and control of different types of storage media are typically different, the solid-state portion of the hybrid drive may include its own corresponding controller function, which may be integrated into a single controller along with the HDD function. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways (such as, as a non-limiting example, using the solid-state memory as a cache memory) to store frequently accessed data, to store I / O intensive data, and the like. Additionally, a hybrid drive may be designed and configured essentially as two storage devices in a single enclosure, i.e., a conventional HDD and an SSD, with an interface for one or more host connections.

[0036] Augmentations and Alternatives In the foregoing description, the embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, various modifications and changes may be made without departing from the broader spirit and scope of the embodiments. Thus, the sole and exclusive indication of what the invention is and what the applicant intends the invention to be is the set of claims issued from this application in the particular form in which the claims are issued, including any subsequent amendments. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms used in the claims. Thus, any limitations, elements, properties, characteristics, advantages, or attributes not expressly set forth in the claims shall not in any way limit the scope of such claims. Thus, the specification and drawings should be regarded in an illustrative sense and not in a restrictive sense.

[0037] Also, certain process steps may be described herein in a particular order, and alphabetic and alphanumeric labels may be used to identify particular steps. Unless otherwise stated herein, embodiments are not necessarily limited to any particular order of performing such steps. In particular, labels are used merely for convenient identification of steps, and are not intended to specify or require a particular order of performing such steps.

Claims

1. 1. A hard disk drive (HDD) including a suspension assembly including a flexure, the flexure comprising: A metal substrate; an insulating base layer on at least a portion of the metal substrate; a first conductive layer on at least a portion of the insulating base layer; a plurality of electrical pads overlying the first conductive layer, each of the electrical pads including a second conductive layer; a preformed bump of solder material predisposed on at least a portion of each electrical pad; a conductive cover layer over at least a portion of each preformed bump of solder material; Including, a HDD.

2. 10. The HDD of claim 1, wherein each conductive cover layer comprises gold.

3. 10. The HDD of claim 1, wherein each conductive cover layer is disposed entirely over and in contact with each preformed bump of solder material.

4. 2. The HDD of claim 1, wherein each conductive cover layer is disposed over and in contact with at least a portion of each electrical pad not covered by a preformed bump of solder material.

5. 10. The HDD of claim 1, wherein the second conductive layer of each electrical pad comprises nickel.

6. the second conductive layer of each electrical pad comprises nickel; each conductive cover layer is disposed over and in contact with only a portion of each second conductive layer; The HDD according to claim 1 .

7. a third conductive layer between the second conductive layer and the preformed bump of solder material. The HDD according to claim 1 .

8. The HDD of claim 7 , wherein the third conductive layer comprises gold.

9. 9. The HDD of claim 8, wherein each conductive cover layer is disposed over and in contact with an entirety of each preformed bump of solder material and at least a portion of each third conductive layer not covered by the preformed bump of solder material.

10. a disk medium rotatably mounted on a spindle; a head slider containing a read / write transducer configured to read from and write to the disk medium, the head slider being mounted to the suspension assembly and electrically connected to the electrical pads of the flexure via solder material of pre-solder bumps; a means for moving the head slider to access a portion of the disk medium; The HDD of claim 1 further comprising:

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