IP Law Daily PTAB properly found patents relating to electronic device heat dissipation obvious
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Friday, June 17, 2016

PTAB properly found patents relating to electronic device heat dissipation obvious

By Cheryl Beise, J.D.

The Patent Trial and Appeal Board did not err in finding that the challenged claims of three patents relating to the use of a graphite sheet to dissipate heat in electronic devices were invalid as obvious in light of prior art, the U.S. Court of Appeals for the Federal Circuit has held. The patents—owned by GrafTech International Holdings, Inc.— were the subjects of inter partes review instituted at the behest of Laird Technologies, Inc. (GrafTech International Holdings, Inc. v. Laird Technologies, Inc., June 17, 2016, Wallach, E.).

Laird sought inter parties review of various claims of U.S. Patent Nos. 6,482,520 ("the ’520 patent"), 6,982,874 ("the ’874 patent"), and 7,292,441 ("the ’441 patent") (collectively, "the patents-in-suit"). In separate final written decisions, the PTAB found the disputed claims of the patents-in-suit invalid as obvious.

The ’520 Patent

The ’520 patent "relates to a system effective for dissipating the heat generated by an electronic component using a thermal management system that includes a thermal interface formed from a flexible graphite sheet and/or a heat sink formed from a graphite article."

The PTAB found claims 1, 2, and 21–23 of the ’520 patent would have been obvious over Japanese Laid-Open Patent Application No. H10-56114 ("Inoue"), in view of the Grafoil Engineering Design Manual ("Grafoil Manual"). The PTAB also found claim 21 obvious over Inoue in view of the Grafoil Manual and an entry from the Thermagon, Inc. website ("Thermagon Paper").

Motivation to combine. Contrary to GrafTech’s argument, substantial evidence supported the PTAB’s finding that a motivation existed to combine Inoue Grafoil Manual and that a PHOSITA would have a reasonable expectation of success in combining the references. Specifically, the PTAB held that Inoue does not require the use of a carbonaceous sheet with a thermal conductivity higher than that of copper or aluminum, but instead found that "a person of skill in the relevant technology . . . would have the requisite skill and creativity to select the appropriate graphite material for the task at hand." Inoue discloses a carbonaceous sheet with a thermal conductivity higher than that of copper or aluminum in its description of one preferred embodiment, but does not make it a requirement, the court noted. An obviousness inquiry is not limited to the prior art’s preferred embodiment, the court said.

Hindsight. The court also disagreed with GrafTech’s assertion that the PTAB’s obviousness analysis rested on impermissible hindsight. GrafTech argued that the graphite sheets disclosed in the disputed claims of the ’520 patent would not meet the thermal conductivity requirement allegedly required by Inoue, such that Inoue teaches away from the claims of the ’520 patent. According to GrafTech, the PTAB "impermissibly used knowledge of GrafTech’s actual invention in its obviousness inquiry."

In assessing whether prior art teaches away from the claimed invention, the PTAB may consider "only knowledge which was within the level of ordinary skill in the art at the time the claimed invention was made," but may not consider the claimed invention itself. However, the PTAB observed that a skilled artisan would be able to select the appropriate graphite for the particular application, including the products in the Grafoil Manual that were available at the time and satisfy the relevant claim elements.

Secondary considerations. The PTAB considered the evidence as to the objective indicia of non-obviousness—commercial success, industry praise, failure of others, and copying—and determined that none of the evidence established a nexus with the subject matter claimed in the ’520 patent.

The court agreed with GrafTech that the PTAB applied an incorrect analysis in assessing commercial success—by comparing the teachings of the prior art to evidence of commercial success, instead of comparing the requirements of the disputed claims of the ’520 patent to evidence of commercial success. Despite this error, GrafTech nevertheless failed to meet its burden of demonstrating the requisite nexus between the claimed invention and the commercial success, according to the court. First, GrafTech submitted the same evidence in each of the inter partes reviews to establish the commercial success of the patents-in-suit, yet the patents are directed to different inventions. Second, GrafTech asserted that the Apple iPhone and Amazon Kindle Fire HD used products covered by the ’520 patent and enjoyed commercial success. GrafTech did not show that the success of those products resulted from the products covered by the ’520 patent.

Expert witness testimony. GrafTech maintained that the PTAB afforded undue weight to testimony from Laird’s expert witness, William Bagot, in reaching its conclusions. The Federal Circuit observed that this argument asked it to reweigh the evidence, which it could not do under the substantial evidence standard of review. In any case, substantial evidence supported the PTAB’s decision to rely upon Mr. Bagot’s testimony, the court noted.

The ’874 and ’411 Patents

The ’874 and ’441 patents relate generally to a "thermal solution for an electronic device, which is positioned between a heat source and an external surface of the electronic device and/or another component of the electronic device." The inventions facilitate heat dissipation from the heat source while shielding the second component from the heat generated by the heat source.

The PTAB found claims 1–20 of the ’874 patent and claims 1–16 of the ’441 patent would have been obvious over various prior art references. GrafTech’s challenge to the PTAB’s obviousness rulings rested solely on the assertion that the PTAB erred in construing the claim term "thermal shielding."

Claim construction. Applying the broadest reasonable interpretation (BRI) standard, the PTAB construed "thermal shielding" in independent claims 1 and 11 of the ’874 patent and independent claim 1 of the ’441 patent to mean "a structure that protects against heat." Because the specification does not define "shield," the PTAB relied upon a dictionary definition to construe "thermal shielding."

GrafTech argued that the PTAB erred by not including its construction the clause "other than the heat source itself." The Federal Circuit disagreed. Adopting GrafTech’s proffered construction would introduce an extraneous limitation into the claims’ terms because the challenged claims already explicitly require a graphite sheet to shield a component other than the heat source itself from the heat generated by that source, the court explained. The court found no error in the PTAB’s construction of the challenged claims.

Finding no errors in the PTAB’s decisions, the Federal Circuit affirmed them in their entireties.

The case is No. 2015-1796, 2015-1797, and 2015-1798.

Attorneys: Erin M. Dunston (Buchanan Ingersoll & Rooney PC) for GrafTech International Holdings, Inc. Matthew L. Cutler (Harness, Dickey & Pierce, PLC) for Laird Technologies, Inc.

Companies: GrafTech International Holdings, Inc.; Laird Technologies, Inc.

MainStory: TopStory Patent FedCirNews

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