UNITED STATES PATENT AND TRADEMARK OFFICE
`__________________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`__________________________________________________________________
`
`NITTO DENKO CORP.,
`
`Petitioner
`
`Patent No. 8,169,746
`Original Issue Date: May 1, 2012
`Title: INTEGRATED LEAD SUSPENSION WITH MULTIPLE TRACE
`CONFIGURATIONS
`_________________________________________________________________
`
`PETITION FOR INTER PARTES REVIEW
`OF U.S. PATENT NO. 8,169,746
`PURSUANT TO 35 U.S.C. § 312 and 37 C.F.R. § 42.104
`
`Case No. IPR2018-01300
`
`__________________________________________________________________
`
`

`

`TABLE OF CONTENTS
`
`II.
`
`I. MANDATORY NOTICES (37 C.F.R. § 42.8) .............................................. 3
`
`Real Party-in-Interest (37 C.F.R. § 42.8(b)(1)) .................................... 3
`
`Related Matters (37 C.F.R. § 42.8(b)(2)) ............................................. 3
`
`Counsel (37 C.F.R. § 42.8(b)(3)) ......................................................... 3
`REQUIREMENTS FOR IPR ......................................................................... 4
` Grounds for Standing ........................................................................... 4
`
`Identification of Challenge and Relief Requested ............................... 4
`
`Claim Construction............................................................................... 6
`1.
`“Interleaved” ............................................................................ 6
`2.
`“ground plane trace” ............................................................... 7
`III. THE ’746 PATENT ........................................................................................ 8
`IV. HOW CHALLENGED CLAIMS ARE UNPATENTABLE ....................... 10
` Overview of the Prior Art ................................................................... 10
`1.
`Balakrishnan ........................................................................... 11
`2.
`Young ...................................................................................... 16
`3.
`Balakrishnan ’152 .................................................................. 18
`4.
`Yuuki ....................................................................................... 21
` Ground 1: Claims 7 and 11 are anticipated by Balakrishnan ............. 23
`1.
`Claim 7 .................................................................................... 23
`a.
`“An integrated lead head suspension flexure
`having a plurality of regions including a tail and
`a gimbal, including:” ................................................... 23
`“First trace sections having a first structural
`configuration on a first region of the flexure” .......... 28
`“Second trace sections having a second
`structural configuration different than the first
`configuration on a second region of the flexure” ...... 30
`“The second trace sections electrically
`connected to the first trace sections” ......................... 32
`
`b.
`
`c.
`
`d.
`
`-i-
`
`

`

`e.
`
`f.
`
`2.
`
`d.
`
`“Wherein the first trace sections include
`interleaved traces” ....................................................... 34
`“The second trace sections include ground
`plane traces” ................................................................. 35
`Claim 11 .................................................................................. 36
`a.
`“An integrated lead head suspension flexure” .......... 37
`b.
`“A mounting region” ................................................... 37
`c.
`A gimbal extending distally from the mounting
`region and having bond pads ...................................... 39
`A tail extending proximally from the mounting
`region and having terminal pads ................................ 43
`First trace sections having a first structural
`configuration electrically connected to the
`terminal pads and extending over at least a
`portion of the tail ......................................................... 45
`f. Wherein the first trace sections extend over
`substantially all of the tail and mounting region ...... 46
`Second trace sections having a second
`structural configuration different than the first
`structural configuration electrically connected
`to the bond pads and extending over at least a
`portion of the gimbal, wherein the second trace
`sections extend over substantially all of the
`gimbal ............................................................................ 50
`Transition structures electrically connecting the
`first trace sections to the second trace sections,
`wherein the transition structures directly
`electrically connect the first and second trace
`sections .......................................................................... 52
`i. Wherein the first trace sections have a first
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces ................................................................... 55
`
`e.
`
`g.
`
`h.
`
`-ii-
`
`

`

`j.
`
`b.
`
`c.
`
`The second trace sections have a second
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces. .................................................................. 55
` Ground 2: Claims 7 and 11 are obvious over Balakrishnan in
`view of Young. ................................................................................... 55
`1.
`Claim 7 .................................................................................... 55
`a.
`“An integrated lead head suspension flexure
`having a plurality of regions including a tail and
`a gimbal, including:” ................................................... 55
`“First trace sections having a first structural
`configuration on a first region of the flexure” .......... 56
`“Second trace sections having a second
`structural configuration different than the first
`configuration on a second region of the flexure” ...... 56
`“The second trace sections electrically
`connected to the first trace sections” ......................... 56
`“Wherein the first trace sections include
`interleaved traces” ....................................................... 56
`“The second trace sections include ground
`plane traces” ................................................................. 58
`Claim 11 .................................................................................. 58
`a.
`“An integrated lead head suspension flexure” .......... 58
`b.
`“A mounting region” ................................................... 58
`c.
`A gimbal extending distally from the mounting
`region and having bond pads ...................................... 59
`A tail extending proximally from the mounting
`region and having terminal pads ................................ 60
`First trace sections having a first structural
`configuration electrically connected to the
`terminal pads and extending over at least a
`portion of the tail ......................................................... 60
`f. Wherein the first trace sections extend over
`substantially all of the tail and mounting region ...... 60
`
`2.
`
`d.
`
`e.
`
`f.
`
`d.
`
`e.
`
`-iii-
`
`

`

`g.
`
`h.
`
`j.
`
`Second trace sections having a second
`structural configuration different than the first
`structural configuration electrically connected
`to the bond pads and extending over at least a
`portion of the gimbal, wherein the second trace
`sections extend over substantially all of the
`gimbal ............................................................................ 60
`Transition structures electrically connecting the
`first trace sections to the second trace sections,
`wherein the transition structures directly
`electrically connect the first and second trace
`sections .......................................................................... 61
`i. Wherein the first trace sections have a first
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces ................................................................... 62
`The second trace sections have a second
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces. .................................................................. 62
`It Would Have Been Obvious To Combine the
`Teachings of Balakrishnan and Young ................................ 62
` Ground 3: Claims 8 and 11 are obvious over Balakrishnan in
`view of Balakrishnan ’152 and Young ............................................... 65
`1.
`Claim 8 .................................................................................... 65
`a.
`“An integrated lead head suspension flexure
`having a plurality of regions including a tail and
`a gimbal, including:” ................................................... 66
`“First trace sections having a first structural
`configuration on a first region of the flexure” .......... 66
`“Second trace sections having a second
`structural configuration different than the first
`configuration on a second region of the flexure” ...... 66
`“The second trace sections electrically
`connected to the first trace sections” ......................... 66
`
`3.
`
`b.
`
`c.
`
`d.
`
`-iv-
`
`

`

`e.
`
`f.
`
`2.
`
`d.
`
`“Wherein the first trace sections include
`stacked traces” ............................................................. 68
`“The second trace sections include ground
`plane traces” ................................................................. 71
`Claim 11 .................................................................................. 71
`a.
`“An integrated lead head suspension flexure” .......... 72
`b.
`“A mounting region” ................................................... 72
`c.
`A gimbal extending distally from the mounting
`region and having bond pads ...................................... 72
`A tail extending proximally from the mounting
`region and having terminal pads ................................ 72
`First trace sections having a first structural
`configuration electrically connected to the
`terminal pads and extending over at least a
`portion of the tail ......................................................... 72
`f. Wherein the first trace sections extend over
`substantially all of the tail and mounting region ...... 73
`Second trace sections having a second
`structural configuration different than the first
`structural configuration electrically connected
`to the bond pads and extending over at least a
`portion of the gimbal, wherein the second trace
`sections extend over substantially all of the
`gimbal ............................................................................ 74
`Transition structures electrically connecting the
`first trace sections to the second trace sections,
`wherein the transition structures directly
`electrically connect the first and second trace
`sections .......................................................................... 74
`i. Wherein the first trace sections have a first
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces ................................................................... 75
`
`e.
`
`g.
`
`h.
`
`-v-
`
`

`

`j.
`
`3.
`
`
`
`The second trace sections have a second
`structural configuration from the set including
`interleaved traces, stacked traces and ground
`plane traces. .................................................................. 75
`It Would Have Been Obvious To Combine the
`Teachings of Balakrishnan, Young and Balakrishnan
`’152 .......................................................................................... 75
`Grounds 4 & 5: Claims 9 and 15 are obvious over Balakrishnan
`in view of Yuuki (Ground 4) and further in view of
`Balakrishnan ’152 or Young (Ground 5). .......................................... 79
`1.
`Claim 9 .................................................................................... 79
`a.
`An integrated lead head suspension flexure
`having a plurality of regions including a tail and
`a gimbal, including: ..................................................... 79
`first trace sections having a first structural
`configuration on a first region of the flexure; ........... 79
`second trace sections having a second structural
`configuration different than the first
`configuration on a second region of the flexure, ....... 80
`the second trace sections electrically connected
`to the first trace sections, ............................................ 80
`wherein the first trace sections are substantially
`impedance matched to the second trace
`sections; ......................................................................... 80
`bond pads on the gimbal having a first
`impedance; and ............................................................ 83
`terminal pads on the tail having a second
`impedance that is different than the first
`impedance, and ............................................................ 85
`wherein the first and second trace sections
`substantially impedance match the first and
`second impedances. ...................................................... 86
`Claim 15 .................................................................................. 87
`a.
`15. An integrated lead head suspension flexure
`including: ...................................................................... 87
`
`2.
`
`b.
`
`c.
`
`d.
`
`e.
`
`f.
`
`g.
`
`h.
`
`-vi-
`
`

`

`d.
`
`e.
`
`f.
`
`g.
`
`h.
`
`i.
`
`b.
`c.
`
`a mounting region; ....................................................... 87
`a gimbal extending distally from the mounting
`region and having bond pads; .................................... 88
`a tail extending proximally from the mounting
`region and having terminal pads; .............................. 88
`first trace sections having a first structural
`configuration electrically connected to the
`terminal pads and extending over at least a
`portion of the tail; ........................................................ 88
`second trace sections having a second structural
`configuration different than the first structural
`configuration electrically connected to the bond
`pads and extending over at least a portion of the
`gimbal; and ................................................................... 88
`transition structures electrically connecting the
`first trace sections to the second trace sections; ....... 88
`wherein the first and second traces are
`substantially impedance matched; and ..................... 89
`the flexure has a first impedance at the bond
`pads that is different than the second
`impedance at the terminal pads. ................................ 89
`It Would Have Been Obvious To Combine the
`Teachings of Balakrishnan, and Yuuki, and also
`Balakrishnan ’152/Young. ..................................................... 89
`CONCLUSION ............................................................................................. 90
`
`3.
`
`V.
`
`-vii-
`
`

`

`LISTING OF EXHIBITS
`
`Exhibit 1007
`
`Exhibit 1008
`Exhibit 1009
`
`Exhibit 1010
`
`Exhibit 1001
`Exhibit 1002
`Exhibit 1003
`Exhibit 1004
`Exhibit 1005
`Exhibit 1006
`
`U.S. Patent No. 8,169,746 to Rice et al.
`File History of U.S. Patent No. 8,169,746 to Rice et al.
`U.S. Patent No. 6,038,102 to Balakrishnan et al.
`U.S. Patent No. 5,717,547 to Young
`U.S. Patent No. 5,737,152 to Balakrishnan et al.
`U.S. Patent Application Publication 2006/0203372 to Yuuki et
`al.
`U.S. Patent Application Serial No. 08/720,836 to Williams et
`al. and file history
`Declaration of Dr. Giora Tarnopolsky
`IEEE Standard Dictionary of Electrical and Electronic Terms,
`definition of “interleave,” 1984, adopted as an American
`National Standard “IEEE Std. 100-1984.”
`Grieg and Engelmann, Microstrip – A New Transmission
`Technique for the Kilomegacycle Range, published in
`Proceedings of the Institute of Radio Engineers (I.R.E.),
`December, 1952.
`U.S. Patent No. 7,092,215 to Someya, et. al.
`T. Ohwe et al., “Development of integrated suspension system
`for a nanoslider with an MR head transducer,” published in
`IEEE Trans. Magnetics, vol. 29, No. 6, pp. 3924-3926,
`February 1993.
`US patent 5,870,252 to Hanrahan
`Exhibit 1013
`US patent 5,491,597 to Bennin et at. (“Bennin.”)
`Exhibit 1014
`Exhibit 1015 WO 98/20485 to Carpenter et al. (“Carpenter.”)
`
`Exhibit 1011
`
`Exhibit 1012
`
`-viii-
`
`

`

`Exhibit 1016
`
`Exhibit 1017
`
`Exhibit 1018
`
`Exhibit 1019
`
`Exhibit 1020
`
`IEEE Standard Dictionary of Electrical and Electronic Terms,
`Second Edition, 1977, adopted as an American National
`Standard “IEEE Std. 100-1977.”
`“Coaxial-Line Discontinuities,” J. R. Whinnery et al.,
`Proceedings of the I.R.E, vol. 32, No. 11, November 1944, pp.
`695-709.
`“Analysis and Design of Head-Preamplifier Connections in
`Read-Write Channels for Magnetic Rigid-Disk Drives,” Arun
`Balakrishnan and Christopher M. Carpenter, IEEE Trans.
`Magn. Vol. 34, No. 1, January 1998 (submitted June 14, 1997.)
`“Electric and Magnetic Fields,” by Stephen S. Attwood, John
`Wiley and Sons, © 1932, 1941, 1949, pp. 422-425.
`“Field and waves in communication electronics,” by Simon
`Ramo et al, John Wiley and Sons, © 1965, 1984, p. 261.
`
`-ix-
`
`

`

`Pursuant to 35 U.S.C. §§ 311-319 and 37 C.F.R. § 42, Petitioner Nitto
`
`Denko Corp. (“Nitto” or “Petitioner”) respectfully requests inter partes review
`
`(“IPR”) of claims 7-9, 11 and 15 of U.S. Patent No. 8,169,746 (“the ’746 patent”).
`
`The ’746 patent identifies Alexander J. Rice et al. as inventors, was filed April 8,
`
`2008, and issued May 1, 2012. According to U.S. Patent and Trademark Office
`
`(“USPTO”) assignment records, the ’746 patent is currently assigned to
`
`Hutchinson Technology Inc. (“HTI” or “Patent Owner”). There is a reasonable
`
`likelihood that Petitioner will prevail with respect to at least one claim challenged
`
`in this Petition.
`
`The ’746 patent relates to a hard drive suspension. A typical suspension
`
`includes a supporting arm, a flexible sheet of material known as a “flexure” that
`
`includes electrical traces, and a slider that holds a read/write head. The electrical
`
`traces connect the read/write head to the circuitry of the hard drive. The ’746
`
`patent’s suspension uses different configurations of the electrical traces in different
`
`regions of the flexure. According to the ’746 patent, reductions in the size of
`
`suspensions purportedly gave rise to a need for electrical traces with a high
`
`bandwidth, low impedance, low stiffness, and a small mechanical footprint. Ex.
`
`1001, 1:33-40. The ’746 patent claims a straightforward solution to this recited
`
`need. In particular, the electrical traces are provided in two sections. One section
`
`uses interleaved or stacked traces, which according to the ’746 patent provide high
`
`-1-
`
`

`

`bandwidth and mid-range impedance, suitable for impedance matching to disk
`
`drive circuits. Id., 5:41-45. The second section uses ground plane traces (i.e.
`
`traces backed by an electrically conductive layer), which have relatively low
`
`stiffness and a small footprint, and relatively low impedance. Id., 5:45-51.
`
`All of the supposed suspension needs purportedly satisfied by the ’746
`
`patent, however, were already well known in the prior art. For instance, the prior
`
`art explicitly recognized that the hard drive industry was decreasing the size of
`
`suspensions in order to improve hard disk performance. Ex. 1003, 2:4-10. It was
`
`also well known that as suspensions became smaller, stiffness became more of an
`
`issue. Id., 2:20-23. The prior art further recognized that as the electrical traces
`
`were moved closer together, the capacitance in the traces increased, negatively
`
`impacting circuit performance. Id., 2:46-57. Likewise, it was well known to
`
`persons of skill in the art (“POSITA”) that making a flexure smaller, to fit on a
`
`smaller suspension, can adversely impact electrical and mechanical performance.
`
`Id. Thus, the ’746 patent did not identify a previously unknown problem with
`
`integrated lead flexures.
`
`The purported solutions that the ’746 patent claims were also known. In
`
`particular, the prior art explicitly recognized that undesirable electrical
`
`performance can be avoided by including traces with two different layouts, in two
`
`different portions of the flexure. Id., 3:40-64. Indeed, numerous prior art
`
`-2-
`
`

`

`references disclose hard drive suspensions using the very types of trace layouts
`
`required by the ’746 patent’s claims. This petition relies on one such reference:
`
`U.S. Patent No. 6,038,102 to Balakrishnan et al. (“Balakrishnan”).
`
`Balakrishnan discloses a hard drive suspension with a flexure very similar to
`
`that of the ’746 patent. Just as the ’746 patent requires, Balakrishnan’s flexure
`
`includes electrical traces that have different structures in different regions.
`
`Specifically, Balakrishnan’s electrical traces use interleaved traces in one region,
`
`and ground plane traces in another region, just like the ’746 patent. In view of this
`
`disclosure, Balakrishnan anticipates claim 7 and 11 of the ’746 patent. And,
`
`Balakrishnan also renders claims 7-9, 11 and 15 of the ’746 patent obvious.
`
`I.
`
`Mandatory Notices (37 C.F.R. § 42.8)
`Real Party-in-Interest (37 C.F.R. § 42.8(b)(1))
`Petitioner Nitto and related corporate entities Nitto, Inc., Nitto Denko Fine
`
`Circuit Technology (Shenzhen) Co., Ltd., Nitto Denko (HK) Co., Ltd., Nitto
`
`Denko Material (Thailand) Co., Ltd., and Mie Nitto Denko Corp. are the real
`
`parties-in-interest.
`
`Related Matters (37 C.F.R. § 42.8(b)(2))
`The ’746 patent is currently at issue in an action pending in the U.S. District
`
`Court for the District of Minnesota captioned Hutchinson Tech. Inc. v. Nitto Denko
`
`Corp. et al., Case No. 17-cv-01992.
`
`Counsel (37 C.F.R. § 42.8(b)(3))
`
`-3-
`
`

`

`Lead Counsel: Alex V. Chachkes (Reg. No. 41,663)
`
`Back-up Counsel: Donald E. Daybell (Reg. No. 50,877)
`
`Back-up Counsel: K. Patrick Herman (Reg. No. 75,018)
`
`Electronic Service information: A34PTABDocket@orrick.com;
`
`D2DPTABDocket@orrick.com; P52PTABDocket@orrick.com
`
`Post and Delivery: Orrick, Herrington, & Sutcliffe LLP, 51 West 52nd Street,
`
`New York, NY 10019; Telephone: 212-506-5000 Facsimile: 212-506-5151
`
`II.
`
`Requirements for IPR
`Grounds for Standing
`Petitioner certifies that the ’746 patent (Ex. 1001) is available for IPR and
`
`that Petitioner is not barred or estopped from requesting this IPR.
`
`Identification of Challenge and Relief Requested
`Petitioner requests inter partes review of and challenges claims 7-9, 11 and
`
`15 of the ’746 patent. Each claim should be found unpatentable and cancelled
`
`because the claim recites an integrated lead head suspension flexure that is
`
`indistinguishable from the prior art. This petition explains the reasons why the
`
`claims are unpatentable, provides details regarding where the various claim
`
`limitations can be found in the prior art, and is accompanied by additional
`
`explanation and support set forth in the attached Declaration of Dr. Giora
`
`Tarnopolsky (Ex 1008, “Tarnopolsky”).
`
`The ’746 patent was filed April 8, 2008 as U.S. application 12/099,523.
`
`-4-
`
`

`

`Thus, the effective filing date is April 8, 2008. The patentability of the ’746 patent
`
`is therefore governed by pre-AIA 35 U.S.C §§ 102/103.
`
`Petitioner relies on the following references, all of which are prior art under
`
`pre-AIA 35 U.S.C. § 102(b):
`
`(1) U.S. Patent No. 6,038,102 to Balakrishnan et al., issued March 14, 2000
`
`(“Balakrishnan,” Exhibit 1003);
`
`(2) U.S. Patent No. 5,717,547 to Young, issued February 10, 1998
`
`(“Young”, Exhibit 1004);
`
`(3) U.S. Patent No. 5,737,152 to Balakrishnan et al., issued April 7, 1998
`
`(“Balakrishnan ’152,” Exhibit 1005); and
`
`(4) U.S. Patent Application Publication 2006/0203372 to Yuuki et al.,
`
`published September 14, 2006 (“Yuuki,” Exhibit 1006).
`
`Petitioner requests that claims 7-9, 11 and 15 be determined unpatentable
`
`and cancelled on the following grounds:
`
`Ground 1: Claims 7 and 11 are anticipated by Balakrishnan.
`
`Ground 2: Claims 7 and 11 are obvious over Balakrishnan in view of
`
`Young.
`
`Ground 3: Claims 8 and 11 are obvious over Balakrishnan in view of
`
`Balakrishnan ’152 and Young.
`
`Ground 4: Claims 9 and 15 are obvious over Balakrishnan in view of
`
`-5-
`
`

`

`Yuuki.
`
`Ground 5: Claims 9 and 15 are obvious over Balakrishnan in view of Yuuki
`
`and further in view of Balakrishnan ’152 or Young
`
`Claim Construction
`A claim term subject to IPR is given its “broadest reasonable construction in
`
`light of the specification.” 37 C.F.R. § 42.100(b). Terms are to be given their
`
`plain meaning unless it is inconsistent with the specification. In re Zletz, 893 F.2d
`
`319, 321 (Fed. Cir. 1989). Petitioner believes that all terms of the ’746 patent’s
`
`claims can be afforded their plain and ordinary meaning, and discusses several
`
`terms further below.
`
`“Interleaved”
`1.
`The plain meaning of “interleave” is “to arrange parts of one sequence of
`
`things or events so that they alternate with parts of one or more other sequences of
`
`things or events and so that each sequence retains its identity.” Ex. 1009 (IEEE
`
`Standard Dictionary of Electrical and Electronics Terms, Third Edition, 1984) at
`
`458; Tarnopolsky, ¶64. This plain and ordinary meaning of “interleaved” is not
`
`inconsistent with the specification.
`
`The specification of the ’746 patent uses the term “interleaved” many times,
`
`but never defines it. See, e.g., Ex. 1001, 1:63-66, 3:23, 3:26-27, 3:31, 3:44, 3:49-
`
`50. An embodiment uses interleaved traces where all of the traces are two-
`
`-6-
`
`

`

`terminal traces. Id., 3:19-24. However, the specification never limits the term
`
`“interleaved” to require that each of the interleaved traces be two-terminal traces.
`
`Thus, a POSITA1 would not understand the ’746 patent’s claims to be limited to
`
`alternating two-terminal traces. Instead, applying the broadest reasonable
`
`construction of the term “interleaved traces,” the claims embrace any type of
`
`alternating traces, including two-terminal, electromagnetically-coupled, or
`
`otherwise, and this is taught by Balakrishnan as discussed below. Tarnopolsky,
`
`¶¶63-66.
`
`“ground plane trace”
`2.
`A “ground plane trace” is well known to POSITAs. Such traces are “similar
`
`in structure to conventional micro strip conductors” (Ex. 1001, 4:41-44) which
`
`have been known since the 1950’s. Ex. 1010, at 1645. A “ground plane trace” is
`
`1 The ordinarily skilled artisan in the technology field of the ’746 patent would
`
`have either: (1) a Bachelor’s degree in electrical engineering or a similar field and
`
`three years of work experience in the disk drive industry, or (2) a Master’s degree
`
`in electrical engineering or a similar field and one year of work experience in the
`
`disk drive industry. One of ordinary skill would be aware of the structure of a hard
`
`drive suspension, and the electrical properties of that suspension’s traces.
`
`Tarnopolsky, ¶¶38-40.
`
`-7-
`
`

`

`simply a trace that is backed by an electrically conductive layer (i.e. a “ground
`
`plane”). Ex. 1001, 4:41-44; Tarnopolsky, ¶67. This electrically conductive layer
`
`can be either the underlying spring metal layer or a separate ground plane layer.
`
`Id., 4:44-52. The spring metal layer can be stainless steel. Id., 2:59-60. In the file
`
`history, the applicants confirmed that ground plane traces included “traces that
`
`extend over portions of the flexure that have a ground plane.” Ex. 1002, at 308
`
`(2/16/2012 Amendment, at 10). Applying this broadest reasonable construction,
`
`Balakrishnan, Young and Balakrishnan ’152 all teach ground plane traces, as
`
`discussed below.
`
`III. The ’746 Patent
`The ’746 patent relates generally to a suspension and “flexure” for a hard
`
`disk drive. Ex. 1001, 2:48-51. A flexure is a long, thin, flexible multilayered sheet
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`that includes electrical traces—backed by insulation and a spring metal layer—to
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`connect a magnetic read/write head to a preamplifier/driver circuit in the hard
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`drive. Id., 2:54-56. The flexure is welded or otherwise mounted to a rigid beam,
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`to form a head suspension assembly. Id., 3:4-10. The ’746 patent explains that its
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`flexure 10 has a gimbal 14 located at the distal end, where the read/write head is
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`attached. Id., 2:50-60. It then has a main body region 12 (mounting region)
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`proximal to the gimbal, where the flexure is mounted onto the rigid beam. Id., 3:4-
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`10. Finally, it has a long tail section 15/16 proximal to the main body region and
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`-8-
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`

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`connecting the electrical traces to the preamplifier. Id., 2:50-55; Tarnopolsky,
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`¶¶27-30.
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`Ex. 1001, Fig. 1 (annotated)
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`The ’746 patent uses interleaved or stacked traces 26 in a region of the
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`flexure where improved electrical characteristics are desired, such as on the tail.
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`Id., 5:40-48. It also uses ground plane traces where a smaller mechanical footprint
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`is desired, such as on the gimbal. Id. Interleaving traces entails positioning
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`another, different trace between two traces of a signal path. See, e.g., id., 3:22-24.
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`Stacking traces entails layering traces one on top of the other, with an insulating
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`layer between them. Id., 7:8-10. A ground plane trace is simply a trace that is
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`-9-
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`

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`backed by an electrically conductive layer (i.e. a “ground plane”). Id., 4:41-44;
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`Tarnopolsky, ¶¶31-32.
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`The ’746 patent further explains that the preamplifier/driver circuit and the
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`magnetic read/write head have different impedances. As a result, according to the
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`patent, the electrical characteristics of the suspension can be improved by
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`designing the traces to impedance match the driver and the magnetic head. Id.,
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`5:3-13. The ’746 patent states that this impedance matching is done by varying the
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`thickness or width of the traces (Id., 4:64-67) or the thickness of the insulating
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`layer (Id., 5:1), to change the impedance of the traces along their length, from a
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`higher impedance that matches the driver at the proximal end of the traces, to a
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`lower impedance that matches the read/write head, at the distal end of the traces.
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`Id., 5:3-13; 5:48-56; Tarnopolsky, ¶¶33-34.
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`IV. How Challenged Claims are Unpatentable
`Overview of the Prior Art
`All of the features required by the claims of the ’746 patent—including the
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`use of electrical traces with two different structural configurations, and the use of
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`impedance matching between a driver circuit and a magnetic head in a hard
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`drive—were known in the prior art as of the patent’s effective filing date. A
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`summary of this prior art follows.
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`-10-
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`

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`Balakrishnan
`1.
`Balakrishnan is identified on the face of the ’746 patent but it was not
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`substantively addressed by the examiner during prosecution, and thus is not subject
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`to Section 325(d). Zscaler, Inc., v. Symantec Corp., IPR2017-01342, 2017 WL
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`5624702, at *4 (PTAB Nov. 16, 2017) (holding that references which were merely
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`disclosed by the Applicant in an IDS, but which were not substantively discussed
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`by the examiner, were not subject to Section 325(d).)
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`Balakrishnan teaches a flexure for a hard disk drive. Ex. 1003, 4:50-58.
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`This flexure is secured to a load beam. Id., 1:43-45, 4:57-58, 6:60-63, Figs. 2 & 3
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`(flexure 15 mounted to load beam assembly 20); Tarnopolsky, ¶¶43-44. With
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`reference to Fig. 3, this flexure includes a gimbal, a main body region where the
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`flexure is secured to the load beam, and a tail.
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`-11-
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`

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`Ex. 1003, Fig. 3 (annotated)
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`The flexure 15 also includes a trace interconnect array 60. Ex. 1003, 2:25-
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`30, 4:12-20, 6:60-63, 7:32-48, Figs. 2, 3. The trace interconnect array 60 includes
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`two pairs of traces, one pair for the read signal path and one pair for the write
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`signal path. Id., 7:53-56. The trace interconnect array is formed on an insulating
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`layer, which in turn is further supported by the flexure or the load beam. Id., 4:16-
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`19, 8:44-47. The trace interconnect array includes two portions. The first portion,
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`extending distally from the end of the tail, is the trace/film segment 62. Id., 7:15-
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`18; Tarnopolsky, ¶¶53-55. This segment includes four sets of traces, each set
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`having an electromagnetically-coupled “passive” conductor 74, 76, 78, 80
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`-12-
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`

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`interleaved between two segments (64a, 64b), …, (70a, 70b). These traces are
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`interleaved traces, as shown in Figs. 4 and 5.
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`Ex. 1003, Figs. 4 & 5 (juxtaposed and annotated)
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`As shown in Figs. 3-5, these traces extend from the proximal end 17 of the
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`load arm assembly 20, to the preamplifier/write driver 54. Id., 7:40-43.
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`Balakrishnan further teaches that these interleaved traces may be extended for
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`virtually the entire distance between the head and the p