Immersion Systems LLC v. Midas Green Technologies LLC

1. Case Identification

• Case #: PGR2021-00104
• Patent #: 10,820,446
• Filed: July 26, 2021
• Petitioner(s): Immersion Systems LLC
• Patent Owner(s): Midas Green Technologies, LLC
• Challenged Claims: 1, 5, 6, and 10

2. Patent Overview

• Title: Appliance Immersion Cooling System
• Brief Description: The ’446 patent discloses an immersion cooling system for electrical appliances, such as computer servers. The system comprises a tank adapted to immerse appliances in a dielectric fluid, a weir integrated into a tank wall to facilitate uniform fluid recovery, a plenum at the tank bottom to dispense fluid uniformly upward, and primary and secondary fluid circulation facilities.

3. Grounds for Unpatentability

Ground 1: Claims 1, 5, 6, and 10 are obvious over Best in view of Krajewski and/or Cray.

• Prior Art Relied Upon: Best (Patent 10,123,463), Krajewski (Patent 5,167,511), and Cray (Patent 4,590,538).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Best discloses the foundational elements of claim 1, including a tank for immersing servers in a dielectric fluid, vertically arranged appliance slots, a primary circulation facility (a plenum for upward fluid flow), a secondary circulation facility for heat extraction, and a control facility. Petitioner asserted that Krajewski and Cray, which teach similar immersion cooling systems, disclose the remaining limitations. Specifically, both references allegedly teach a weir structure that controls fluid overflow for uniform recovery and a manifold or inlet column structure that functions as a plenum to uniformly distribute coolant.
  • Motivation to Combine: A POSITA would combine these references because they all address the same field of immersion cooling for electronics and seek to solve well-known problems such as achieving uniform flow, managing floor space, and accommodating vertically stacked components. The ’446 patent itself identifies Krajewski and Cray as prior art examples of immersion cooling systems, providing an explicit reason to consider their teachings. The combination was argued to be a predictable application of known techniques.
  • Expectation of Success: A POSITA would have a strong expectation of success because the combination involves integrating well-understood components from analogous systems. Petitioner noted that the ’446 patent claims lack a key "weir/reservoir" limitation that was added to its parent application to overcome prior art, making the challenged claims a broader, more basic framework that is more susceptible to an obviousness combination.

Ground 2: Claims 1, 5, 6, and 10 are obvious over Best in view of Oktay.

• Prior Art Relied Upon: Best (Patent 10,123,463) and Oktay (Patent 3,406,244).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner relied on Best for the same foundational teachings as in Ground 1. To supply the weir element, Petitioner pointed to Oktay, which describes an immersion cooling system for a "computer memory array" using a container with a "plurality of overflow orifices." Petitioner argued these orifices function as a weir, as their overflow contributes to cooling and increases the system's heat transfer rate, thereby facilitating uniform fluid recovery. Oktay also discloses vertically mounted components and a heat exchanger.
  • Motivation to Combine: A POSITA would combine Best with Oktay because both are directed to immersion cooling of electronics. Oktay's approach to cooling vertically stacked components using an overflow mechanism to enhance efficiency would have been a known design choice to a POSITA seeking to improve the system in Best. The combination represents solving known problems using established techniques from the same field.

Ground 3: Claims 1, 5, 6, and 10 are obvious over Best in view of Gryzhin.

• Prior Art Relied Upon: Best (Patent 10,123,463) and Gryzhin (Russian Federation Patent No. 2500013C1).

• Core Argument for this Ground:

  • Prior Art Mapping: Relying again on Best for the base system, Petitioner argued that Gryzhin teaches the remaining claim limitations. Gryzhin allegedly discloses a modular immersion cooling system with vertical slots for electronic components. Petitioner asserted that the "back wall of the container" in Gryzhin functions as a weir by controlling the fluid level, and a "pressure pipe 42" at the bottom of the container serves as a plenum to dispense coolant uniformly upward through the appliance slots.
  • Motivation to Combine: A POSITA would be motivated to combine the teachings because both references are in the immersion cooling field and address identical design challenges. Petitioner contended that Gryzhin's design for a modular system already solved the issues of vertical stacking, floor space, and uniform flow that the ’446 patent purports to address, making it an obvious source for modification of Best’s system.

• Additional Grounds: Petitioner asserted that claims 1, 5, 6, and 10 are obvious over Best alone. Petitioner also challenged the claims as invalid for indefiniteness under 35 U.S.C. §112(b) and for lack of written description under 35 U.S.C. §112(a).

4. Key Claim Construction Positions

• Petitioner argued that while no specific constructions are necessary for its obviousness grounds, the claim phrase "a weir... adapted to facilitate substantially uniform recovery of the dielectric fluid" is indefinite under §112(b).
• The core of the argument was that the specification lacks any description of a specific structure or "adaptation" of the weir that performs the claimed function. This uncertainty was allegedly compounded during prosecution of the parent application, where the applicant distinguished between a "weir" and a "weir... having an overflow lip" without ever clarifying the structural difference, leaving a POSITA unable to ascertain the scope of the claims with reasonable certainty.

5. Arguments Regarding Discretionary Denial

• §325(d): Petitioner argued that discretionary denial is unwarranted because the same or substantially the same prior art and arguments were never considered by the examiner. Gryzhin is new art, and while Krajewski, Cray, and Oktay were cited, they were not substantively applied in a rejection. Petitioner contended the allowance of the ’446 patent was based on a series of examiner errors, including relying on a non-prior-art reference in the parent case and subsequently allowing the ’446 claims despite the removal of the sole feature previously identified as patentable.
• Fintiv: Petitioner argued against denial under Fintiv, stating that the parallel district court litigation is in its early stages, with no claim construction ruling issued and minimal investment by the parties. Furthermore, the key prior art references asserted in the petition (Oktay and Gryzhin) are not at issue in the district court case, meaning the substantive issues do not overlap.

6. Relief Requested

• Petitioner requests institution of Post-Grant Review and cancellation of claims 1, 5, 6, and 10 of the ’446 patent as unpatentable under 35 U.S.C. §103 and invalid under 35 U.S.C. §112.