PTAB

IPR2020-00825

Asetek Danmark AS v. CoolIT Systems Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Fluid Heat Exchanger for Liquid Cooling of Electronic Devices
  • Brief Description: The ’266 patent discloses a fluid heat exchanger and system for liquid cooling of electronic components, such as computer processors. The core technology involves a "split-flow" design where coolant is introduced into microchannels at a midway point, causing the flow to divide into two sub-flows that proceed in opposite directions toward the ends of the microchannels.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1 and 9 - Claims 1 and 9 are anticipated by Bezama under 35 U.S.C. §102.

  • Prior Art Relied Upon: Bezama (Application # 2010/0012294).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Bezama, which discloses a cooler assembly for electronic devices, teaches every element of independent claim 1. Bezama’s assembly includes a housing with a recessed region, a heat sink with fins defining microchannels, and a compliant separator sheet that functions as the claimed "manifold body." Petitioner asserted this separator sheet has "compliant surfaces" that flank a central opening and urge against the fins, defining a flow boundary as required. For claim 9, Petitioner argued that Bezama’s design inherently results in the claimed bifurcated, or split, flow of coolant within the microchannels.

Ground 2: Obviousness of Claims 1 and 9 - Claims 1 and 9 are obvious over Lyon in view of Bezama under 35 U.S.C. §103.

  • Prior Art Relied Upon: Lyon (Application # 2009/0071625) and Bezama (Application # 2010/0012294).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Lyon discloses a microchannel-based heat exchanger featuring a split-flow design that meets all limitations of claims 1 and 9, with the key exception that Lyon uses a rigid plate rather than a manifold with "compliant surfaces."
    • Motivation to Combine: A POSITA would combine Lyon’s heat exchanger with Bezama’s teaching of a compliant separator sheet. Bezama explicitly taught that using a compliant material to cover the microchannel fins improves sealing, prevents coolant bypass ("short-circuit" flow), and crucially, reduces manufacturing costs by eliminating the need for difficult and expensive high-tolerance control over fin heights.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in making this modification. Bezama’s express teachings about the advantages and implementation of a compliant material provided a clear roadmap to predictably solve a known manufacturing and performance issue in the art.

Ground 3: Obviousness of Claims 13, 14, and 15 - Claims 13, 14, and 15 are obvious in view of Kang.

  • Prior Art Relied Upon: Kang (Application # 2006/0096738).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued Kang discloses a microchannel heat exchanger that teaches the limitations of claim 13. Kang’s device includes a cooling plate with microfins (walls), a flow distributor (plate) overlying the walls, and a press-fit between the distributor and a housing shoulder that creates a "seal." Petitioner contended that Kang’s distributor plate has an "aperture" that delivers fluid between the ends of the microchannels, creating a bifurcated flow that exits at opposite ends, as claimed.
    • Motivation to Combine: While Kang teaches a complex design with multiple alternating inlet and outlet channels across the plate, Petitioner argued a POSITA would have been motivated to simplify this to a single inlet and two outlets located at the ends of the microchannels. This modification represented a well-known design choice to simplify the structure, reduce manufacturing complexity, and lower costs.
    • Expectation of Success: The simplification of Kang's flow arrangement to a standard split-flow configuration was a routine engineering choice with predictable results in performance and manufacturability.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 2, 4, and 5 are obvious over Bezama in view of Chiang (Patent 7,688,589) to add an integrated pump, and that claims 13, 14, and 15 are also obvious over Anderson (Application # 2008/0301941), which taught a similar split-flow concept that a POSITA would have been motivated to simplify.

4. Key Claim Construction Positions

  • "seal" (claim 13): Petitioner proposed construing "seal" to mean "the housing and the plate are fitted so that fluid cannot flow out from between them." This construction was argued to be broad enough to cover embodiments where the seal is formed by fluid-tight contact or by fusing parts together, not just a separate component like an O-ring. Petitioner asserted this construction was necessary to avoid reading out embodiments disclosed in the ’266 patent specification.
  • "exhaust manifold" (claims 1 and 5): Petitioner proposed construing this term to mean "a region into which several smaller channels lead." This construction was based on the specification and general engineering principles, defining the area where fluid collects after exiting the microchannels.

5. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Challenge: Petitioner argued that claims 1, 2, 4, 5, and 9 are not entitled to their asserted 2007 priority date and should be limited to a priority date of July 27, 2011. The contention was that the claim limitation "a pair of compliant surfaces flanking the opening" constituted new matter that was first disclosed in a 2011 provisional application. This argument was critical to the petition, as it established that references like Bezama (published 2010) and Lyon (published 2009) qualify as prior art under §102(b) against these claims.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1, 2, 4, 5, 9, 13, 14, and 15 of the ’266 patent as unpatentable.