Co-planar shielded write traces for disk drive head suspensions

The present invention relates generally to disk drive head suspensions. In particular, the invention is an integrated lead flexure for a suspension.

Disk drive head suspensions with wireless or integrated lead flexures are generally known and disclosed, for example, in the following U.S. Patents, all of which are incorporated herein by reference.

The continuing development of read/write head and related disk drive technology requires head suspensions having improved mechanical and electrical specifications. For example, there is a need for suspensions having increased signal current carrying capabilities, higher data rates and reduced size. Unfortunately, optimizing features of the suspensions to meet these goals is increasingly difficult. It is known, for example, that current carrying capabilities can be increased by widening the traces or decreasing the distance between adjacent traces. But constraints on the size of portions of the flexure traversed by the traces can limit the size of the traces. Although it is known that data rates can be increased by removing portions of the stainless steel spring metal below the traces (i.e. windowing), this approach can lead to higher impedances. There remains, therefore, a continuing need for improved integrated lead flexures.

The present invention is an integrated lead head suspension flexure that provides enhanced signal transmission bandwidth without increases in impedance. One embodiment of the flexure includes a spring metal base layer, an insulating layer on the base layer and traces on the insulating layer. The traces comprise first and second adjacent and co-planar write traces and first and second shield traces. The shield traces are on opposite sides of the write traces, electrically interconnected and generally co-planar with the write traces. Another embodiment of the flexure includes windows in the spring metal layer below the write and shield traces.

FIG. 1 is an illustration of a disk drive head suspension having a flexure in accordance with the present invention.

FIG. 2 is a detailed illustration of the gimbal region of the flexure shown in FIG. 1 .

FIG. 3 is a detailed illustration of a portion of the base region of the flexure shown in FIG. 1 .

FIG. 4 is a cross section of a portion of the flexure base region shown in FIG. 3 , taken at line 4 - 4 in FIG. 3 .

FIG. 5 is a cross section of another portion of the flexure base region shown in FIG. 3 , taken at line 5 - 5 in FIG. 3 .

FIG. 6 is a detailed illustration of a portion of the tail of the flexure shown in FIG. 1 .

A disk drive head suspension 8 including a flexure 10 having co-planar shielded write traces 11 in accordance with one embodiment of the present invention is illustrated generally in FIG. 1 . Suspension 8 is a three-piece assembly in the illustrated embodiment, and includes a load beam 12 and base plate 14 in addition to the flexure 10 . Load beam 12 , which is typically formed from stainless steel, includes a beam region 16 , hinge or spring region 18 and mounting region 20 . Rails 22 are formed on the side edges of the beam region 16 . Base plate 14 is welded to the mounting region 20 at the proximal end of the load beam 12 .

Flexure 10 is an integrated lead or wireless flexure and includes a mounting or base region 24 that is welded or otherwise attached to the beam region 16 of load beam 12 , a gimbal region 26 at its distal end, and a tail 28 extending from the proximal end of the base region. The gimbal region 26 includes a pair of laterally-spaced spring arms 30 1 and 30 2 extending from the base region 24 , and a slider mounting region 32 that extends from and is supported by and between the spring arms. A plurality of head bond pads 34 are located on the gimbal region 26 adjacent to the slider mounting region 32 . A plurality of terminal pads 36 are located on the proximal end of the flexure tail 28 . In addition to write traces 11 , read traces 13 , shield traces 15 1 and 15 2 and ground traces 17 1 and 17 2 extend along the flexure 10 between the head bond pads 34 and terminal pads 36 .

FIG. 2 is a detailed illustration of the gimbal region 26 of flexure 10 . As shown, the head bond pads 34 include first and second adjacent write pads 34 W1 and 34 W2 , first and second adjacent read pads 34 R1 and 34 R2 , shield bond pad 34 S1 and ground bond pad 34 G1 . Two write traces 11 1 and 11 2 extend from the write bond pads 34 W1 and 34 W2 , respectively, around the gimbal spring arm 30 1 to the flexure base region 24 . As shown in FIG. 2 , the write traces 11 1 and 11 2 are adjacent to one another (i.e., there is no trace between them) throughout the gimbal region 26 . A first shield trace 15 1 extends from the shield bond pad 34 S2 along and adjacent to write trace 11 1 around the gimbal spring arm 30 1 to the base region 24 . A second shield trace 15 2 is connected to the shield bond pad 34 S1 and extends along and adjacent to the write trace 11 2 around the gimbal spring arm 30 1 to the base region 24 . The shield traces 15 1 and 15 2 are co-planer with and located on opposite sides of the write traces 11 1 and 11 2 on the first spring arm 30 1 of the gimbal region 26 . Although not shown, portions of the traces 11 , 15 and 17 can be protected by a covercoat.

A pair of adjacent ground traces 17 1 and 17 2 extend from ground bond pad 34 G1 around the gimbal spring arm 30 2 to the flexure base region 24 . As shown, the ground traces 17 1 and 17 2 are connected to the ground pad 34 G1 through a bifurcation link 44 . First and second read traces 13 1 and 13 2 extend from the read bond pads 34 R1 and 34 R2 , respectively, around the gimbal spring arm 30 2 to the flexure base region 24 . As shown in FIG. 2 , the read traces 13 1 and 13 2 are adjacent to one another throughout the gimbal region 26 .

Base region 24 and portions of the gimbal region 26 including the spring arms 30 1 and 30 2 and slider mounting region 32 are formed from a spring metal layer 50 . Stainless steel is commonly used for the spring metal layer 50 in applications of this type. Portions of the electrical structures including bond pads 34 , write traces 11 , read traces 13 , shield traces 15 and ground traces 17 that overlay the spring metal layer 50 are spaced and electrically insulated from the spring metal layer by an insulating layer 52 . Polyimide is commonly used for the insulating layer 52 in applications of this type. The portions of write traces 11 1 and 11 2 and shield traces 15 1 and 15 2 that extend around spring arm 30 1 between the head bond pads 34 and the base region 24 are backed by the insulating layer 52 . These portions of the traces 11 1 , 11 2 , 15 1 and 15 2 and the backing of insulating layer 52 are outrigger trace portions in the illustrated embodiment, and are located outside the spring arm 30 1 , opposite the spring arm from the slider mounting region 32 . A tab (not shown in FIG. 2 ) in the spring metal layer 50 can extend from the spring arm 30 1 to support the outrigger portions of the traces 11 1 , 11 2 , 15 1 and 15 2 and the backing of insulating layer 52 . Similarly, a tab (not shown) can extend from the spring arm 30 2 and supports outrigger portions of the traces 13 1 , 13 2 , 17 1 and 17 2 and the backing of insulating layer 52 . The head bond pads 34 can be flying pads, and extend over a window (not shown in FIG. 2 ) in the spring metal layer 50 . In other embodiments of the invention (not shown) some or all of the head bond pads and portions or all of the write, read, shield and ground traces can be backed by or overlay the spring metal layer (e.g., the traces can be over the spring arms). In still other embodiments of the invention (not shown) the gimbal region 26 can include interconnects and/or vias or other structures for electronically connecting ground bond pad 34 G1 and/or shield pad 34 S1 to the stainless steel layer 50 .

FIG. 3 is a detailed top view of a portion of the flexure base region 24 . FIGS. 4 and 5 are sectional views of portions of the base region 24 shown in FIG. 3 . As shown, write traces 11 1 and 11 2 are immediately adjacent and parallel to one another. Shield trace 15 1 is opposite write trace 11 1 from write trace 11 2 , and is immediately adjacent and parallel to the write trace 11 1 . Similarly, shield trace 15 2 is opposite write trace 11 2 from write trace 11 1 , and is immediately adjacent and parallel to the write trace 11 2 . Traces 11 1 , 11 2 , 15 1 and 15 2 are generally co-planar. Traces 11 1 , 11 2 , 15 1 and 15 2 are thereby grouped together, with shield traces 15 1 and 15 2 bordering the pair of adjacent write traces 11 1 and 11 2 . Windows 70 in the spring metal layer 50 are located below portions of the traces 11 1 , 11 2 , 15 1 and 15 2 .

Read traces 13 1 and 13 2 and ground trace 17 1 are also grouped together and spaced from the group of traces 11 1 , 11 2 , 15 1 and 15 2 . Ground trace 17 2 is connected and merged into ground trace 17 1 at a location (shown in FIG. 2 ) between the portion of flexure base region 24 shown in FIG. 3 and the gimbal region 26 , and is not visible in FIG. 3 . As shown, read traces 13 1 and 13 2 are immediately adjacent and parallel to one another. Ground trace 17 1 is opposite read trace 13 2 from read trace 13 1 , and is immediately adjacent and parallel to the read trace 13 2 . The illustrated embodiment of flexure base region 24 includes the spring metal layer 50 below the traces 13 1 , 13 2 and 17 1 . Other embodiments of the invention (not shown) include windows such as 70 below the traces 13 1 , 13 2 and 15 3 . Although not shown in FIGS. 3-5 , portions of all of the flexure base region 24 can be covered by a covercoat.

As shown in FIGS. 3 and 5 , the shield traces 15 1 and 15 2 include connection vias 72 at periodically spaced locations along their lengths. Connection vias 72 are conductive members that extend through the insulating layer 52 and electrically connect the shield traces 15 1 and 15 2 to one another through the spring metal layer 50 .

FIG. 6 is an illustration of a portion of the tail 28 of flexure 10 . As shown, the write traces 11 1 and 11 2 terminate at terminal pads 36 W1 and 36 W2 , respectively. The shield trace 15 1 adjacent to write trace 11 1 terminates at terminal pad 36 S2 . A connection via 80 also connects the shield trace 15 1 to the spring metal layer 50 through the insulating layer 52 at a location on the tail 28 distal to the terminal pad 36 S1 . The shield trace 15 2 adjacent to write trace 11 2 terminates at a connection via 82 at a location on the tail 28 distal to the terminal pads 36 . Connection via 82 electrically connects the shield trace 15 2 to the spring metal layer 50 through the insulating layer 52 . Read traces 13 1 and 13 2 terminate at terminal pads 36 R1 and 36 R2 , respectively. The ground trace 17 1 adjacent to read trace 13 1 terminates at terminal pad 36 G1 . Terminal pads 36 are flying leads in the illustrated embodiment and extend over a window 84 in the spring metal layer 50 . In other embodiments (not shown) the terminal pads 36 overlay the spring metal layer 50 . Although not shown in FIG. 5 , portions of the tail 28 such as traces 11 1 , 11 2 , 13 1 , 13 2 , 15 1 , 15 2 and 17 1 can be covered by a covercoat.

When incorporated into a disk drive (not shown) the terminal pads 36 W1 and 36 W2 are interconnected to electronic circuits (also not shown) to receive write signals. These write signals are then electrically coupled through the write traces 11 1 and 11 2 and bond pads 34 W1 and 34 W2 to the write head terminals of a slider (not shown) mounted to the slider mounting region 32 on the gimbal region 26 . The terminal pad 36 S1 is interconnected to a ground or other common potential in the drive electronic circuits, thereby effectively connecting shield traces 15 1 and 15 2 and the spring metal layer 50 to the ground. Research has shown that the shield traces 15 1 and 15 2 effectively function as shields in connection with the write traces 11 1 and 11 2 . The electromagnetic coupling during signal transmission is substantially between the write traces 11 1 and 11 2 and the shield traces 15 1 and 15 2 . The result is enhanced electrical performance, including higher bandwidth signal transmission and reduced signal loss without increased impedance. Cross-talk between the write traces 11 1 and 11 2 and the read traces 13 1 and 13 2 will also decrease with increasing space between the write and read traces on the flexure 10 .

The read bond pads 34 R1 and 34 R2 on gimbal region 26 are connected to the read head terminals of a slider (not shown) mounted to the slider mounting region 32 . The read signals are electrically coupled through the read traces 13 , and 13 2 to terminal pads 36 R1 and 36 R2 . The terminal pads 36 R1 and 36 R2 are interconnected to electronic circuits (not shown) in a disk drive to receive the read signals. A ground terminal associated with the magnetic head of the slider is connected to the ground bond pad 34 G1 on gimbal region 26 and coupled to the disk drive electronic circuits through the ground trace 17 1 and terminal pad 36 G1 . Although in the illustrated embodiment read traces 13 1 and 13 2 are not bounded by co-planer shielding ground traces, and the stainless steel layer 50 is free of windows in the regions below the traces, these features and associated advantages are incorporated into other embodiments of the invention. Flexure 10 can be manufactured using conventional or otherwise known additive and/or subtractive processes including photolithography, wet and dry etching and deposition processes.

Although the shield traces 15 1 and 15 2 are shown connected to ground potential in the illustrated embodiment, they are connected to other potentials in other embodiments (not shown). In still other embodiments the shield traces 15 1 and 15 2 can be electrically floating with respect to the potential on write traces 11 1 and 11 2 . Shield traces 15 1 and 15 2 will typically be of the same (or floating) potential, and are preferably connected to one another.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.